Change search
Refine search result
23338233392334023341233422334323344 1167001 - 1167050 of 1200544
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1167001.
    Zhang, Hong Qiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Lanzhou University, China.
    Akram, Nadeem
    Stockholm University, Faculty of Science, Department of Physics.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Transmission of highly charged ions through mica nanocapillaries of rectangular cross-section2017In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 408, p. 61-66Article in journal (Refereed)
    Abstract [en]

    We investigated the transmission of 7-keV Ne7+ ions through nanocapillaries of rectangular cross-section in phlogopite mica both by experiments and computer simulations. In the experiment, the role of the deposited charge in the transmitted ion intensity and angular distribution was studied. It is found that the rhombic angular profile is degraded during the process of rearrangement of the deposited charge on the capillary walls. Trajectory simulations are performed to understand the shaping of ion beam by the image force at tilt angles within the geometrical opening angle, as well as the degrading of the shaping due to the deposited charge when the tilt angle is larger than the geometrical opening angle. This reveals the interplay of the deposited charge and the image charge on the shaping of the ion beams when transmitting them through nanocapillaries of various geometrical cross sections.

  • 1167002.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Bcl-xL and bcl-2 proteins in melanoma progression and UVB-induced apoptosis.2006In: International Journal of Oncology, ISSN 1019-6439, Vol. 28, no 3, p. 661-666Article in journal (Refereed)
    Abstract [en]

    Whether bcl-xL and bcl-2 play an essential role in melanoma progression and UVB-induced apoptosis is not completely understood. We investigated the expression of bcl-xL and bcl-2 in matched primary and metastatic melanoma tumors and melanoma cell lines from the same melanoma patients to clarify the importance of bcl-xL and bcl-2 in melanoma progression and in UVB-induced apoptosis. The expression of bcl-xL and bcl-2 proteins was examined by immunohisto(cyto)chemistry and Western blot in melanoma tumors and melanoma cells. Cellular viability and apoptosis were estimated after the melanoma cells were exposed to 30, 60 and 180 mJ/cm2 UVB. Both primary melanoma tumors and melanoma cells showed lower expression of bcl-xL and bcl-2 proteins estimated as frequency of positive cells than their matched metastatic tumors and cells in vitro. After exposure to UVB, the cell viability decreased and the number of apoptotic cells increased in both primary and metastatic melanoma cell lines. These changes were more pronounced in the primary melanoma cells than in the matched metastatic cells. After UVB exposure, the expression of bcl-xL protein decreased in primary melanoma cells in a dose- and time-dependent manner, but the expression of bcl-2 was not influenced. The expression of bcl-xL and bcl-2 proteins was increased during melanoma progression from primary to metastatic melanoma. Reduction of bcl-xL, but not bcl-2 expression was involved in UVB-induced apoptosis in primary melanoma cells.

  • 1167003.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Deletion in p16INK4a and loss of p16 expression in human skin primary and metastatic melanoma cells.2004In: International Journal of Oncology, ISSN 1019-6439, Vol. 24, no 2, p. 331-335Article in journal (Refereed)
    Abstract [en]

    p16INK4a gene mapped at chromosome 9p21 region encodes a tumor suppressor protein p16 which is frequently inactivated in human cancers, including skin melanoma. In order to clarify the importance of p16 alterations in melanoma, we examined the deletions of p16INK4a and expression of p16 protein in eight unselected primary and metastatic melanoma cell lines from human skin melanomas. Normal skin melanocytes were used as controls. Deletions of entire exons in the p16INK4a gene were detected by PCR technique and expression of the p16 protein was examined by Western blotting and immunocytochemistry. Results showed that the fragments from exons 2A, 2C and 3 in p16INK4a gene were totally deleted in the metastatic melanoma cell line, FM28.7 and the fragment from exon 3 was deleted in the metastatic melanoma cell line, FM55M2. P16 protein was strongly expressed in two of the primary melanomas cell lines (FM55P and RaH3). The p16 protein was weakly expressed in one of the metastatic melanoma cell lines (FM55M1) and negative in the other metastasis (FM55M2) as compared to their matched primary melanoma cells (FM55P). The p16 protein was strongly expressed in normal skin melanocytes. Immunocytochemistry showed that p16 protein was mainly localized in the nuclei of the melanoma cells and normal melanocytes, if it was expressed. Deletions of p16INK4a gene was uncommon and loss of p16 protein expression was common event in melanoma, especially in the later stages of melanoma.

  • 1167004.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Expression of oncogenes, tumour suppressor, mismatch repair and apoptosis-related genes in primary and metastatic melanoma cells.2001In: International Journal of Oncology, ISSN 1019-6439, Vol. 19, no 6, p. 1149-1153Article in journal (Refereed)
    Abstract [en]

    Several genetic alterations have been implicated in the development of malignant melanoma, but the expression of oncogenes, tumour suppressor, mismatch repair and apoptosis-related genes and their interactions in melanoma have not been completely clarified. We simultaneously examined the expression of p73, c-erbB-2, ras, p53, Mdm2, p27, DCC, hMLH-1, hMSH-2, bcl-2, Bax and NF-kappaB, by immunocytochemistry, in both primary and metastatic melanoma cell lines derived from melanoma patients. p73 was expressed in 7/8 cell lines, but stronger expressed in the metastatic cells than in the primary melanoma cells. c-erbB-2 was detected in all 8 cell lines and ras in 2/5 metastases. p53 was found in all the cell lines and Mdm2 in 1/8 of the cell lines. In the same patient, the intensity of p27 expression was decreased from the primary to the metastatic tumours. bcl-2 was expressed in all the cell lines. Bax was absent in 5/8 cell lines. In the same patient, Bax was weakly expressed in the primary tumour but lacking in the metastases. The data demonstrate that overexpression of p73, c-erbB-2, p53 and bcl-2, and loss of Mdm2 and Bax may interact and play important roles in the development and aggressiveness of human melanoma.

  • 1167005.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Expression of p27 and MAPK proteins involved in all-trans retinoic acid-induced apoptosis and cell cycle arrest in matched primary and metastatic melanoma cells.2004In: International Journal of Oncology, ISSN 1019-6439, Vol. 25, no 5, p. 1241-1248Article in journal (Refereed)
    Abstract [en]

    We investigated whether p27 and mitogen-activated protein kinase (MAPK) proteins were involved in all-trans retinoic acid (atRA)-induced apoptosis and cell cycle arrest. Matched primary and metastatic melanoma cells were exposed to atRA. Apoptosis and cell cycle were detected by flow cytometry. Expression of p27, Ras, B-raf, Mek and Erk proteins was examined. Results showed that atRA induced apoptosis and cell cycle arrest in both primary and metastatic melanoma cells. The primary melanoma cells were more vulnerable than their matched metastatic cells. Expression of p27 was increased, while MAPK proteins were decreased, this response was dose- and time-dependent. Alterations of these proteins were more pronounced in primary melanoma cells than in the matched metastases. These data indicate that up-regulation of p27 and down-regulation of MAPK proteins were involved in atRA-induced apoptosis and cell cycle arrest in melanoma.

  • 1167006.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Expression profiles of Id1 and p16 proteins in all-trans-retinoic acid-induced apoptosis and cell cycle re-distribution in melanoma2005In: Cancer Letters, ISSN 0304-3835, E-ISSN 1872-7980, Vol. 217, no 1, p. 33-41Article in journal (Refereed)
    Abstract [en]

    All-trans-retinoic acid (atRA) exerts its effects via apoptosis and cell cycle re-distribution. However, the mechanisms behind the effects have not been fully understood. In this study, we used a model system of matched primary and metastatic melanoma cells to investigate whether expression of Id1 and p16 proteins were involved in atRA-induced apoptosis and cell cycle re-distribution. Melanoma cells were exposed to 0.1 or 10 μM atRA for 1-96 h. Apoptosis and cell cycle were measured by flow cytometry. Expression of Id1 and p16 proteins was examined by Western blotting and immunocytochemistry. After exposure to atRA we found a marked increase in apoptosis and cell cycle re-distribution in both primary and metastatic melanoma cells. Expression level of Id1 protein was decreased and the p16 was increased in a dose- and time-dependent (P<0.05) manner after treatment with atRA. Alterations of these proteins were more pronounced in the primary melanoma cells than the matched metastases (P<0.05). These data suggested that the alterations of Id1 and/or p16 proteins were involved in atRA-induced apoptosis and cell cycle re-distribution in melanoma. These expression profiles of Id1 and p16 proteins may provide molecular evidence for better chemotherapy primarily for early stages of melanoma.

  • 1167007.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Expression profiles of p53, p21, bax and bcl-2 proteins in all-trans-retinoic acid treated primary and metastatic melanoma cells.2004In: International Journal of Oncology, ISSN 1019-6439, Vol. 25, no 2, p. 303-308Article in journal (Refereed)
    Abstract [en]

    We have previously shown that all-trans-retinoic acid (atRA) induces apoptosis in melanoma cells and primary melanoma cells are more sensitive to the exposure of atRA than the matched metastases. However, mechanisms behind the atRA-induced apoptosis have not been studied. In this study, we used a similar cell culture model system of matched primary and metastatic melanoma cells from the same patient to investigate whether p53 and bcl-2 family proteins were involved in atRA-induced apoptosis. The primary and metastatic melanoma cells were exposed to 0.1 and 10 micro M atRA in serum-free RPMI 1640 cell culture medium in the dark for up to 96 h. The protein expression of p53, p21, bax and bcl-2 were examined by Western blotting and immunocytochemistry. Expression of p53, p21 and bax was increased, and bcl-2 was decreased in melanoma cells after exposure to atRA at different concentrations for various periods of time. The changes of p53, p21, bax, and bcl-2 protein levels were dose- and time-dependent. The primary melanoma cells were more sensitive to the atRA treatments than cells from matched metastatic melanoma. These data indicate that p53, p21, bax and bcl-2 proteins were involved in atRA-induced apoptosis in melanoma cells. Modification of these protein levels in the tumour cells might be beneficial for early treatment of melanoma.

  • 1167008.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Ultraviolet A and B differently induce intracellular protein expression in human skin melanocytes - A speculation of separate pathways in initiation of melanoma2003In: Carcinogenesis, ISSN 0143-3334, E-ISSN 1460-2180, Vol. 24, no 12, p. 1929-1934Article in journal (Refereed)
    Abstract [en]

    Ultraviolet (UV) irradiation has been involved in both initiation and promotion of carcinogenesis in melanoma. Alterations of cellular proliferation proteins, such as p73, Nup88, Id1 and p27 have been considered to play critical roles in melanoma development. However, the molecular mechanisms behind melanoma carcinogenesis are still poorly understood. In this study, we used human skin melanocytes as an experimental model system to investigate effects of UV irradiation on protein expression concerning cellular proliferation. The melanocytes prepared from human foreskin were separately exposed to various doses of UVA or UVB and post-cultivated for 24 or 48 h. Total proteins were isolated from the melanocytes, and expression of p73, Nup88, Id1, p27, bcl-2 and proliferating cell nuclear antigen (PCNA) proteins was examined by western blotting and immunocytochemistry. Results showed that expression of p73 and Nup88 was enhanced by UVA irradiation in a dose- and time-dependent manner. However, expression of Id1, p27, bcl-2 and PCNA proteins was not changed upon exposure to the UVA. Id1 and p27 proteins were over-expressed by exposure to UVB, but expression of p73, Nup88, bcl-2 and PCNA proteins was not changed by the UVB irradiation. The data suggested that UVA and UVB irradiation might lead to alterations of the different intracellular proteins. UVA enhanced protein expression concerning cell growth (p73 and Nup88) and UVB might over-express proteins concerning cellular proliferation (Id1 and p27). UVA and UVB may induce initiation of melanoma via separate intracellular pathways.

  • 1167009.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology.
    Satyamoorthy, K
    Herlyn, M
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    All-trans retinoic acid (atRA) differentially induces apoptosis in matched primary and metastatic melanoma cells - A speculation on damage effect of atRA via mitochondrial dysfunction and cell cycle redistribution2003In: Carcinogenesis, ISSN 0143-3334, E-ISSN 1460-2180, Vol. 24, no 2, p. 185-191Article in journal (Refereed)
    Abstract [en]

    All-trans retinoic acid (atRA) has been suggested to exert its cytotoxicity via apoptosis but the mechanisms behind the damage effects have not been fully understood. In this study, we investigated the cytotoxic effects of atRA in eleven primary and matched metastatic cutaneous melanoma cell lines. All the primary and metastatic melanoma cell lines examined expressed the retinoic acid receptors. The cultured melanoma cells treated with atRA showed dysfunction of mitochondria and altered cell cycle distribution, inhibited cell proliferation and apoptosis. The cytotoxic effects of atRA were dose- and time-dependent. The dysfunction of mitochondria and altered cell cycle distribution, inhibited cell proliferation and apoptosis. The cytotoxic effects of atRA were dose- and time-dependent. The dysfunction of mitochondria and induction of apoptosis were more pronounced in the primary tumor cells than in the metastatic cell lines from the same patients. The data indicate that the cytotoxic effect of atRA was mediated through dysfunction of mitochondria, alterations in cell cycle and induction of apoptosis. Melanoma in early stage may have better response to atRA adjuvant therapy than the melanoma in late stage, suggesting the early utility of atRA in melanoma chemotherapy.

  • 1167010.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology.
    Schneider, José
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Expression of p16, p27, p53, p73 and Nup88 proteins in matched primary and metastatic melanoma cells.2002In: International Journal of Oncology, ISSN 1019-6439, Vol. 21, no 1, p. 43-48Article in journal (Refereed)
    Abstract [en]

    Cutaneous melanoma is a tumor with high metastatic potential, but the mechanisms leading to progression are still not fully understood. In this study, we examined whether p16, p27, p53, p73 and Nup88 proteins were involved in the progression from primary to metastatic melanomas by immunocytochemistry and Western blotting in eleven melanoma cell lines from five matched primary and metastatic melanomas. We demonstrated that the primary and metastatic melanomas expressed differently p16, p27, p73 and Nup88 proteins. When expressed in the primary melanoma cells p16 and p27 were lost or reduced in almost all the metastatic melanoma cell lines. In contrast, p73 and Nup88 were expressed in most of the tested melanoma cell lines and were increased in the metastatic melanomas. p53 was expressed at the same level in both the primary and metastatic melanoma cells. These data suggest that a reduced expression of p16 and p27 and an enhanced expression of p73 and Nup88 might play an important role in the progression of melanoma from primary tumor to metastasis.

  • 1167011.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology.
    Sun, Xiao-Feng
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Oncology.
    Loss of p27 expression predicts poor prognosis in patients with Dukes' B stage or proximal colorectal cancer.2001In: International Journal of Oncology, ISSN 1019-6439, Vol. 19, no 1, p. 49-52Article in journal (Refereed)
    Abstract [en]

    p27 is a cyclin-dependent kinase inhibitor which regulates progression of cells from G1 into S phase in a cell cycle. Loss of the negative regulator may contribute to oncogenesis and tumor progression. The aim of this study was to examine p27 expression in normal mucosa, primary and metastatic tumors from patients with colorectal adenocarcinomas and to analyze association of p27 with patient survival and clinicopathological variables. p27 expression was estimated by immunohistochemistry in 178 primary colorectal cancers, 34 lymph node metastases and 48 normal mucosa samples from patients with colorectal adenocarcinoma. Associations of p27 with patient survival, clinicopathological characteristics and expression of p53, p73 and DCC were analyzed. Loss of p27 was found in 51% of primary tumors, 68% of metastases and 56% of normal samples. The intensity of p27 staining was similar in the matched primary tumor, metastasis and normal mucosa. In patients with Dukes' B or with proximal tumors, the loss of p27 predicted poorer prognosis (p = 0.03 and p = 0.05, respectively). However, there were no significant differences in the patients with other individual Dukes' stage or distal tumors. No relationships were found between p27 and patients' gender, age, tumor location, growth pattern and expression of p53, p73 and DCC (p > 0.05). The data suggest that loss of p27 was associated with poor prognosis in patients with Dukes' B tumor or those with proximal tumor. p27 might be a useful marker to identify the more progressive tumors in these groups.

  • 1167012.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Dermatology.
    Sun, Xiao-Feng
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Oncology.
    Overexpression of cyclooxygenase-2 correlates with advanced stages of colorectal cancer2002In: American Journal of Gastroenterology, ISSN 0002-9270, E-ISSN 1572-0241, Vol. 97, no 4, p. 1037-1041Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: We aimed to investigate the associations of cyclooxygenase-2 (COX-2) with pathological features and survival in patients with colorectal cancer. METHODS: The expression of COX-2 was examined by immunohistochemistry in 112 primary colorectal cancers, with 64 samples from the corresponding normal mucosa and 16 metastases in the regional lymph nodes of patients with colorectal cancer. The associations of COX-2 expression with clinico-pathological features, including survival, were analyzed. RESULTS: The frequency and intensity of COX-2 staining were remarkably increased from the normal samples (17%) to the primary tumors (72%) and to the metastases (100%). Expressions of COX-2 were 25%, 74%, 78%, and 67% in Dukes' A, B, C, and D tumors, respectively (p = 0.005), and positively related to proliferative activity (p = 0.003). COX-2 expressions were 80% in colonic tumors and 60% in rectal tumors (p = 0.03). The expression of COX-2 was positively related to the better differentiated tumors in the colon (p = 0.04). We were unable to find any relationship of COX-2 with patient age, sex, tumor growth pattern, apoptosis, and patient survival (p > 0.05). CONCLUSION: We found that the expression of COX-2 was upregulated from normal cells to primary tumors and to metastases, and related to proliferative activity, tumor location, Dukes' stage, and differentiation. These results further support the evidence that COX-2 may be involved in tumorigenesis and development of colorectal cancer. ⌐ 2002 by Am. Coll. of Gastroenterology.

  • 1167013.
    Zhang, Hong
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology.
    Sun, Xiao-Feng
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Oncology. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Oncology UHL.
    Synnerstad, Ingrid
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Rosdahl, Inger
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of dermatology and venereology. Östergötlands Läns Landsting, Centre for Medicine, Department of Dermatology and Venerology in Östergötland.
    Importance of FAS-1377, FAS-670, and FASL-844 polymorphisms in tumor onset, progression, and pigment phenotypes of Swedish patients with melanoma: a case-control analysis.2007In: Cancer Journal, ISSN 0765-7846, E-ISSN 1292-8658, Vol. 13, no 4, p. 233-237Article in journal (Refereed)
    Abstract [en]

    PURPOSE: Human skin melanoma at later stages usually has an extremely poor prognosis. It is of importance to search for biologic markers to identify and monitor individuals at risk for melanoma for early diagnosis and to avoid tumor progression. The FAS gene and its natural ligand (FASL) gene initiate the death signal cascade, playing a central role in the apoptotic signaling pathway and tumor growth and metastasis. PATIENTS AND METHODS: In this study, we analyzed polymorphisms in 229 patients with melanoma and 351 age- and gender-matched tumor-free individuals. Genomic DNAs were isolated from mononuclear cells in peripheral vein blood, and the polymorphisms were examined with polymerase chain reaction-restriction fragment length polymorphism techniques. Frequency in distribution of the polymorphisms was compared between the patients with melanoma and the healthy control subjects, and associations with patients' pigment phenotypes, age at diagnosis, and melanoma characteristics were analyzed. RESULTS AND CONCLUSIONS: The FAS-1377, FAS-670, and FASL-844 polymorphisms were not found to be markers of melanoma risk (P > 0.05). In patients with melanoma, frequencies of the FAS-1377, FAS-670, and FASL-844 polymorphisms were different between the patients aged <50 and > or =50 years (P < or = 0.025, P < or = 0.025, and P < or = 0.01). Moreover, the FAS-670 polymorphism correlated with tumor Breslow thickness (P < or = 0.01) and Clark level (P < or = 0.001) and was associated with tumors developing in sun-exposed locations (P < or = 0.001). FAS and FASL were not markers for melanoma risk but might be important in the development and progression of sun-induced melanoma independently of skin type.

  • 1167014.
    Zhang, Hong
    et al.
    University of Skövde, School of Life Sciences.
    Sun, Xiao-Feng
    Department of Biomedicine and Surgery, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
    Synnerstad, Ingrid
    Division of Dermatology, Department of Clinical and Experimental Medicine, Linköping University, Sweden.
    Rosdahl, Inger
    Division of Dermatology, Department of Clinical and Experimental Medicine, Linköping University, Sweden.
    Importance of FAS-1377, FAS-670 and FASL-844 Polymorphisms in Tumor Onset, Progression and Pigment Phenotypes of Swedish Patients With Melanoma: A Case-Control Analysis2007In: The Cancer Journal, ISSN 1528-9117, E-ISSN 1540-336X, Vol. 13, no 4, p. 233-237Article in journal (Refereed)
    Abstract [en]

    PURPOSE: Human skin melanoma at later stages usually has an extremely poor prognosis. It is of importance to search for biologic markers to identify and monitor individuals at risk for melanoma for early diagnosis and to avoid tumor progression. The FAS gene and its natural ligand (FASL) gene initiate the death signal cascade, playing a central role in the apoptotic signaling pathway and tumor growth and metastasis. PATIENTS AND METHODS: In this study, we analyzed polymorphisms in 229 patients with melanoma and 351 age- and gender-matched tumor-free individuals. Genomic DNAs were isolated from mononuclear cells in peripheral vein blood, and the polymorphisms were examined with polymerase chain reaction-restriction fragment length polymorphism techniques. Frequency in distribution of the polymorphisms was compared between the patients with melanoma and the healthy control subjects, and associations with patients' pigment phenotypes, age at diagnosis, and melanoma characteristics were analyzed. RESULTS AND CONCLUSIONS: The FAS-1377, FAS-670, and FASL-844 polymorphisms were not found to be markers of melanoma risk (P > 0.05). In patients with melanoma, frequencies of the FAS-1377, FAS-670, and FASL-844 polymorphisms were different between the patients aged <50 and > or =50 years (P < or = 0.025, P < or = 0.025, and P < or = 0.01). Moreover, the FAS-670 polymorphism correlated with tumor Breslow thickness (P < or = 0.01) and Clark level (P < or = 0.001) and was associated with tumors developing in sun-exposed locations (P < or = 0.001). FAS and FASL were not markers for melanoma risk but might be important in the development and progression of sun-induced melanoma independently of skin type.

  • 1167015.
    Zhang, Hong
    et al.
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Wang, Da-Wei
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre. Department of Stomatology, The Third Hospital of Hebei Medical University, Hebei, China.
    Adell, Gunnar
    Department of Oncology, Karolinska University Hospital, Karolinska, Sweden.
    Sun, Xiao-Feng
    Division of Oncology, Department of Clinical and Experimental Medicine, Faculty of Heath Science, Linköping University, Sweden .
    WRAP53 is an independent prognostic factor in rectal cancer- a study of Swedish clinical trial of preoperative radiotherapy in rectal cancer patients2012In: BMC Cancer, ISSN 1471-2407, E-ISSN 1471-2407, Vol. 12, p. 294-Article in journal (Refereed)
    Abstract [en]

    Background: Expression of WRAP53 protein has oncogenic properties and it is up regulated in several types of tumors. Methods: We examined expression of WRAP53 protein in rectal cancers and analyzed its relationship to the response to preoperative radiotherapy and patient survival. The WRAP53 protein was examined by immunohistochemistry in normal mucosa, primary tumors and lymph node metastases from 143 rectal cancer patients participated in a Swedish clinical trial of preoperative radiotherapy. Results: Frequency of WRAP53 protein expression was increased in primary rectal cancer compared to the normal mucosa (p < 0.05). In non-radiotherapy group positive WRAP53 in primary tumors (p = 0.03, RR, 3.73, 95% CI, 1.13-11.89) or metastases (p = 0.01, RR, 4.11, 95% CI, 1.25-13.14), was associated with poor prognosis independently of stages and differentiations. In radiotherapy group, positive WRAP53 in the metastasis correlated with better survival (p = 0.04). An interaction analysis showed that the correlations of WRAP53 with the prognostic significance with and without radiotherapy in the metastasis differed (p = 0.01). In the radiotherapy group, expression of WRAP53 in metastases gave a better outcome (p = 0.02, RR, 0.32, 95% CI, 0.13-0.84), and an interaction analysis showed significance between the two groups (p = 0.01). Conclusion: WRAP53 may be a new biomarker used to predict prognosis and to select suitable patients for preoperative radiotherapy.

  • 1167016.
    Zhang, Hong
    et al.
    University of Skovde, Sweden .
    Wang, Da-Wei
    University of Skovde, Sweden Hebei Medical University, Peoples R China .
    Adell, Gunnar
    Karolinska University Hospital, Sweden .
    Sun, Xiao-Feng
    Linköping University, Department of Clinical and Experimental Medicine, Oncology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology UHL.
    WRAP53 is an independent prognostic factor in rectal cancer- a study of Swedish clinical trial of preoperative radiotherapy in rectal cancer patients2012In: BMC Cancer, ISSN 1471-2407, E-ISSN 1471-2407, Vol. 12, no 294Article in journal (Refereed)
    Abstract [en]

    Background: Expression of WRAP53 protein has oncogenic properties and it is up regulated in several types of tumors. less thanbrgreater than less thanbrgreater thanMethods: We examined expression of WRAP53 protein in rectal cancers and analyzed its relationship to the response to preoperative radiotherapy and patient survival. The WRAP53 protein was examined by immunohistochemistry in normal mucosa, primary tumors and lymph node metastases from 143 rectal cancer patients participated in a Swedish clinical trial of preoperative radiotherapy. less thanbrgreater than less thanbrgreater thanResults: Frequency of WRAP53 protein expression was increased in primary rectal cancer compared to the normal mucosa (p andlt; 0.05). In non-radiotherapy group positive WRAP53 in primary tumors (p = 0.03, RR, 3.73, 95% CI, 1.13-11.89) or metastases (p = 0.01, RR, 4.11, 95% CI, 1.25-13.14), was associated with poor prognosis independently of stages and differentiations. In radiotherapy group, positive WRAP53 in the metastasis correlated with better survival (p = 0.04). An interaction analysis showed that the correlations of WRAP53 with the prognostic significance with and without radiotherapy in the metastasis differed (p = 0.01). In the radiotherapy group, expression of WRAP53 in metastases gave a better outcome (p = 0.02, RR, 0.32, 95% CI, 0.13-0.84), and an interaction analysis showed significance between the two groups (p = 0.01). less thanbrgreater than less thanbrgreater thanConclusion: WRAP53 may be a new biomarker used to predict prognosis and to select suitable patients for preoperative radiotherapy.

  • 1167017.
    Zhang, Hong
    et al.
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Widegren, Emma
    Linkoping Univ, Dept Oncol, Inst Clin & Expt Med, Linkoping, Sweden .
    Wang, Da-Wei
    Hebei Med Univ, Hosp 3, Dept Stomatol, Shijiazhuang, Peoples R China.
    Sun, Xiao-Feng
    Linkoping Univ, Dept Oncol, Inst Clin & Expt Med, Linkoping, Sweden .
    SPARCL1: a potential molecule associated with tumor diagnosis, progression and prognosis of colorectal cancer2011In: Tumor Biology, ISSN 1010-4283, E-ISSN 1423-0380, Vol. 32, no 6, p. 1225-1231Article in journal (Refereed)
    Abstract [en]

    We investigated whether SPARCL1 played an essential role in tumor initiation, formation and progression of colorectal carcinomas. In this study, we examined expression of SPARCL1 protein in the normal colorectal mucosa, adjacent normal mucosa and primary and lymph node metastases from colorectal cancer patients. In matched patients, we found that SPARCL1 was negative in the distant normal colorectal mucosa, weakly expressed in the adjacent normal mucosa, strongly expressed in primary colorectal adenocarcinomas and slightly expressed in their lymph node metastases. A similar pattern was observed in the SPARCL1 expression from our series of non-matched colorectal cancer patients. The strongest expression and highest frequency of the SPARCL1 protein were found in the primary cancers. Interestingly, in the primary tumors, the frequency of SPARCL1 expression was significantly increased from the Dukes' A to Dukes' B tumors and then decreased gradually from the Dukes' B to C and D tumors. There was no difference in the intensity of SPARCL1 expression between the central areas and invasion margins of the primary tumors. Moreover, the SPARCL1 protein was more strongly expressed in the highly differentiated tumors than the lower differentiated ones. The patients with positive expression of SPARCL1 in their tumors had worse prognosis than the patients with SPARCL1-negative ones, even after the analyses by Multivariate and Interaction method. Expression of SPARCL1 protein might be a valuable biomarker for early diagnosis in colorectal cancers and further predicting patients' prognosis.

  • 1167018.
    Zhang, Hong
    et al.
    University of Skovde.
    Widegren, Emma
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Oncology.
    Wang, Da-Wei
    University of Skovde.
    Sun, Xiao-Feng
    Linköping University, Department of Clinical and Experimental Medicine, Oncology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology UHL.
    SPARCL1: a potential molecule associated with tumor diagnosis, progression and prognosis of colorectal cancer2011In: Tumor Biology, ISSN 1010-4283, E-ISSN 1423-0380, Vol. 32, no 6, p. 1225-1231Article in journal (Refereed)
    Abstract [en]

    We investigated whether SPARCL1 played an essential role in tumor initiation, formation and progression of colorectal carcinomas. In this study, we examined expression of SPARCL1 protein in the normal colorectal mucosa, adjacent normal mucosa and primary and lymph node metastases from colorectal cancer patients. In matched patients, we found that SPARCL1 was negative in the distant normal colorectal mucosa, weakly expressed in the adjacent normal mucosa, strongly expressed in primary colorectal adenocarcinomas and slightly expressed in their lymph node metastases. A similar pattern was observed in the SPARCL1 expression from our series of non-matched colorectal cancer patients. The strongest expression and highest frequency of the SPARCL1 protein were found in the primary cancers. Interestingly, in the primary tumors, the frequency of SPARCL1 expression was significantly increased from the Dukes A to Dukes B tumors and then decreased gradually from the Dukes B to C and D tumors. There was no difference in the intensity of SPARCL1 expression between the central areas and invasion margins of the primary tumors. Moreover, the SPARCL1 protein was more strongly expressed in the highly differentiated tumors than the lower differentiated ones. The patients with positive expression of SPARCL1 in their tumors had worse prognosis than the patients with SPARCL1-negative ones, even after the analyses by Multivariate and Interaction method. Expression of SPARCL1 protein might be a valuable biomarker for early diagnosis in colorectal cancers and further predicting patients prognosis.

  • 1167019.
    Zhang, Hong
    et al.
    University of Örebro, Sweden.
    Zhu, Zhen-Long
    Hebei Medical University, Peoples R China.
    Wang, Da-Wei
    Hebei Medical University, Peoples R China.
    Yang, Yan-Hong
    Hebei Medical University, Peoples R China.
    Wang, Hao
    Hebei Medical University, Peoples R China.
    Sun, Xiao-Feng
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology. Linköping University, Faculty of Medicine and Health Sciences.
    Upregulation of nucleoporin 88 is associated with nodal metastasis and poor differentiation in oral squamous cell carcinoma2016In: International Journal of Clinical and Experimental Medicine, ISSN 1940-5901, E-ISSN 1940-5901, Vol. 9, no 5, p. 8399-8404Article in journal (Refereed)
    Abstract [en]

    Nucleoporin 88 (Nup 88) is a component of the nuclear pore complexes (NPCs) that mediates nucleocytoplasmic trafficking of macromolecules, Nup 88 has been reported to be up-regulated in a wide variety of malignancies. Studies show that overexpression of this antigen is associated with the development, agressiveness, differentiation and prognosis in some tumours. Since no study has been carried out in the relationship between the Nup 88 expression and clinicopathological features in the patients with oral squamous cell carcinoma (OSCC), this study aimed to determine Nup 88 expression in OSCC and its clinicopathological significance. Nup 88 expression was examined by immunohistochemistry in 20 normal oral mucosa specimens and 83 OSCC tissues. The frequency of positive Nup 88 expression was gradually increased from normal oral mucosa (10%) to primary OSCC (40%, P=0.012). The Nup 88 positive rate in OSCC patient with nodal metastasis was significantly higher than those without nodal metastasis (64% vs. 21%, P=0.000085). The frequency of positive Nup 88 expression was significantly different between worse and better differentiation (80 vs. 27%, P=0.000024). Nup 88 expression was not related to the patients gender, age, location and tumour size (Pamp;gt;0.05). In conclusion, Nup 88 may play an important role in tumorigenesis in oral squamous cell carcinoma. Upregulation of Nup 88 is associated with nodal metastasis and poor differentiation in oral squamous cell carcinoma.

  • 1167020.
    Zhang, Hong
    et al.
    Örebro University, School of Medical Sciences.
    Zhu, Zhen-Long
    Department of Pathology, The First Hospital of Hebei Medical University, Shijiazhuang, China.
    Wang, Da-Wei
    Department of Stomatology, The Third Hospital of Hebei Medical University, Shijiazhuang, China.
    Yang, Yan-Hong
    Department of Pathology, The First Hospital of Hebei Medical University, Shijiazhuang, China.
    Wang, Hao
    Department of Stomatology, The Third Hospital of Hebei Medical University, Shijiazhuang, China.
    Sun, Xiao-Feng
    Division of Oncology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, University of Linköping, Linköping, Sweden.
    Upregulation of nucleoporin 88 is associated with nodal metastasis and poor differentiation in oral squamous cell carcinoma2016In: International Journal of Clinical and Experimental Medicine, ISSN 1940-5901, E-ISSN 1940-5901, Vol. 9, no 5, p. 8399-8404Article in journal (Refereed)
    Abstract [en]

    Nucleoporin 88 (Nup 88) is a component of the nuclear pore complexes (NPCs) that mediates nucleocytoplasmic trafficking of macromolecules, Nup 88 has been reported to be up-regulated in a wide variety of malignancies. Studies show that overexpression of this antigen is associated with the development, agressiveness, differentiation and prognosis in some tumours. Since no study has been carried out in the relationship between the Nup 88 expression and clinicopathological features in the patients with oral squamous cell carcinoma (OSCC), this study aimed to determine Nup 88 expression in OSCC and its clinicopathological significance. Nup 88 expression was examined by immunohistochemistry in 20 normal oral mucosa specimens and 83 OSCC tissues. The frequency of positive Nup 88 expression was gradually increased from normal oral mucosa (10%) to primary OSCC (40%, P=0.012). The Nup 88 positive rate in OSCC patient with nodal metastasis was significantly higher than those without nodal metastasis (64% vs. 21%, P=0.000085). The frequency of positive Nup 88 expression was significantly different between worse and better differentiation (80 vs. 27%, P=0.000024). Nup 88 expression was not related to the patients' gender, age, location and tumour size (P>0.05). In conclusion, Nup 88 may play an important role in tumorigenesis in oral squamous cell carcinoma. Upregulation of Nup 88 is associated with nodal metastasis and poor differentiation in oral squamous cell carcinoma.

  • 1167021.
    Zhang, Hongbin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Mathematics.
    Pricing Asian Options using Monte Carlo Methods2009Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 1167022.
    Zhang, Hongbin
    et al.
    IFW Dresden eV.
    Richter, Manuel
    IFW Dresden eV.
    Koepernik, Klaus
    IFW Dresden eV.
    Opahle, Ingo
    University of Frankfurt.
    Tasnadi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Eschrig , Helmut
    IFW Dresden eV.
    Electric-field control of surface magnetic anisotropy: a density functional approach2009In: NEW JOURNAL OF PHYSICS, ISSN 1367-2630 , Vol. 11, no 043007Article in journal (Refereed)
    Abstract [en]

    In a recent experiment, Weisheit et al ( 2007 Science 315 349) demonstrated that the coercivity of thin L1(0) FePt and FePd films can be modified by the external electric field in an electrochemical environment. Here, this observation is confirmed by density functional calculations for the intrinsic magnetic anisotropy. The origin of the effect is clarified by means of a general and simple method to simulate charged metal surfaces. It is predicted that the coercivity of thin CoPt films is much more susceptible to electric field than that of FePt films.

  • 1167023.
    Zhang, Hongpeng
    et al.
    Xidian Univ, Peoples R China.
    Yuan, Lei
    Xidian Univ, Peoples R China.
    Jia, Renxu
    Xidian Univ, Peoples R China.
    Tang, Xiaoyan
    Xidian Univ, Peoples R China.
    Hu, Jichao
    Xian Univ Technol, Peoples R China.
    Zhang, Yimen
    Xidian Univ, Peoples R China.
    Zhang, Yuming
    Xidian Univ, Peoples R China.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Stress-induced charge trapping and electrical properties of atomic-layer-deposited HfAlO/Ga2O3 metal-oxide-semiconductor capacitors2019In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 52, no 21, article id 215104Article in journal (Refereed)
    Abstract [en]

    Electrical properties and trapping characteristics of an atomic layer deposited Al-rich HfAlO/beta-Ga2O3 capacitor were evaluated via constant-voltage stress (CVS), capacitance-voltage (C-V), and current-voltage (I-V) measurements. The magnitude of the stress-induced charge trapping increases with increasing voltage and time. The effective charges (N-eff) including the border traps located in near-interface oxide, interface traps (D-it) of HfAlO/beta-Ga2O3 interface, and fixed charges contribute significantly to the observed charge trapping, and it is found that interface traps contribute more under a large stress bias, compared with border traps. In addition, the effective charge density is increased with stress time, implying that the contribution of negative sheet charges during the CVS process might not be negligible. Measurements of oxide permittivity (10.74), interface state density (D-it similar to 1 x 10(12) eV(-1) cm(-2)), and gate leakage current (1.18 x 10( -5) A cm(-2) at +10 V) have been extracted, suggesting the great electrical properties of Al-rich HfAlO/beta-Ga203 MOSCAP. According to the above analysis, Al-rich HfAlO is an attractive candidate for normally off Ga2O3 transistors.

  • 1167024. Zhang, Hongqi
    et al.
    Brandenburg, Axel
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Nordic Institute for Theoretical Physics (Nordita). University of Colorado, USA.
    Solar Kinetic Energy and Cross Helicity Spectra2018In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 862, no 2, article id L17Article in journal (Refereed)
    Abstract [en]

    We develop a formalism that treats the calculation of solar kinetic energy and cross helicity spectra in an equal manner to that of magnetic energy and helicity spectra. The magnetic helicity spectrum is shown to be equal to the vertical part of the current helicity spectrum divided by the square of the wavenumber. For the cross helicity, we apply the recently developed two-scale approach globally over an entire active region to account for the sign change between the two polarities. Using vector magnetograms and Dopplergrams of NOAA. 11158 and 12266, we show that kinetic and magnetic energy spectra have similar slopes at intermediate wavenumbers, where the contribution from the granulation velocity has been removed. At wavenumbers around 0.3 Mm(-1), the magnetic helicity is found to be close to its maximal value. The cross helicity spectra are found to be within about 10% of the maximum possible value. Using the two-scale method for NOAA. 12266, the global cross helicity spectrum is found to be particularly steep, similarly to what has previously been found in theoretical models of spot generation. In the quiet Sun, by comparison, the cross helicity spectrum is found to be small.

  • 1167025.
    Zhang, Hongqi
    et al.
    Chinese Acad Sci, Key Lab Solar Act, Natl Astron Observ, Beijing 100012, Peoples R China..
    Brandenburg, Axel
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA. Stockholm Univ, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden.;Univ Colorado, JILA, Boulder, CO 80303 USA.;Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80303 USA.;Stockholm Univ, AlbaNova Univ Ctr, Dept Astron, SE-10691 Stockholm, Sweden.;Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA..
    Solar Kinetic Energy and Cross Helicity Spectra2018In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 862, no 2, article id L17Article in journal (Refereed)
    Abstract [en]

    We develop a formalism that treats the calculation of solar kinetic energy and cross helicity spectra in an equal manner to that of magnetic energy and helicity spectra. The magnetic helicity spectrum is shown to be equal to the vertical part of the current helicity spectrum divided by the square of the wavenumber. For the cross helicity, we apply the recently developed two-scale approach globally over an entire active region to account for the sign change between the two polarities. Using vector magnetograms and Dopplergrams of NOAA. 11158 and 12266, we show that kinetic and magnetic energy spectra have similar slopes at intermediate wavenumbers, where the contribution from the granulation velocity has been removed. At wavenumbers around 0.3 Mm(-1), the magnetic helicity is found to be close to its maximal value. The cross helicity spectra are found to be within about 10% of the maximum possible value. Using the two-scale method for NOAA. 12266, the global cross helicity spectrum is found to be particularly steep, similarly to what has previously been found in theoretical models of spot generation. In the quiet Sun, by comparison, the cross helicity spectrum is found to be small.

  • 1167026. Zhang, Hongqi
    et al.
    Brandenburg, Axel
    Nordita, Sweden; Stockholm University, Sweden; University of Colorado, United States;.
    Sokoloff, D. D.
    EVOLUTION OF MAGNETIC HELICITY AND ENERGY SPECTRA OF SOLAR ACTIVE REGIONS2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 819, no 2, article id 146Article in journal (Refereed)
    Abstract [en]

    We adopt an isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field to estimate the magnetic energy and helicity spectra as well as current helicity spectra of two individual active regions (NOAA. 11158 and NOAA. 11515) and the change of the spectral indices during their development as well as during the solar cycle. The departure of the spectral indices of magnetic energy and current helicity from 5/ 3 are analyzed, and it is found that it is lower than the spectral index of the magnetic energy spectrum. Furthermore, the fractional magnetic helicity tends to increase when the scale of the energy-carrying magnetic structures increases. The magnetic helicity of NOAA. 11515 violates the expected hemispheric sign rule, which is interpreted as an effect of enhanced field strengths at scales larger than 30-60Mm with opposite signs of helicity. This is consistent with the general cycle dependence, which shows that around the solar maximum the magnetic energy and helicity spectra are steeper, emphasizing the large-scale field.

  • 1167027. Zhang, Hongqi
    et al.
    Brandenburg, Axel
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Nordic Institute for Theoretical Physics (Nordita). University of Colorado, USA.
    Sokoloff, D. D.
    EVOLUTION OF MAGNETIC HELICITY AND ENERGY SPECTRA OF SOLAR ACTIVE REGIONS2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 819, no 2, article id 146Article in journal (Refereed)
    Abstract [en]

    We adopt an isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field to estimate the magnetic energy and helicity spectra as well as current helicity spectra of two individual active regions (NOAA. 11158 and NOAA. 11515) and the change of the spectral indices during their development as well as during the solar cycle. The departure of the spectral indices of magnetic energy and current helicity from 5/ 3 are analyzed, and it is found that it is lower than the spectral index of the magnetic energy spectrum. Furthermore, the fractional magnetic helicity tends to increase when the scale of the energy-carrying magnetic structures increases. The magnetic helicity of NOAA. 11515 violates the expected hemispheric sign rule, which is interpreted as an effect of enhanced field strengths at scales larger than 30-60Mm with opposite signs of helicity. This is consistent with the general cycle dependence, which shows that around the solar maximum the magnetic energy and helicity spectra are steeper, emphasizing the large-scale field.

  • 1167028. Zhang, Hongqi
    et al.
    Brandenburg, Axel
    Stockholm University, Nordic Institute for Theoretical Physics (Nordita). Stockholm University, Faculty of Science, Department of Astronomy.
    Sokoloff, D. D.
    MAGNETIC HELICITY AND ENERGY SPECTRA OF A SOLAR ACTIVE REGION2014In: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 784, no 2, p. L45-Article in journal (Refereed)
    Abstract [en]

    We compute for the first time the magnetic helicity and energy spectra of the solar active regionNOAA 11158 during 2011 February 11-15 at 20 degrees southern heliographic latitude using observational photospheric vector magnetograms. We adopt the isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field. The sign of the magnetic helicity turns out to be predominantly positive at all wavenumbers. This sign is consistent with what is theoretically expected for the southern hemisphere. The magnetic helicity normalized to its theoretical maximum value, here referred to as relative helicity, is around 4% and strongest at intermediate wavenumbers of k approximate to 0.4Mm(-1), corresponding to a scale of 2 pi/k approximate to 16 Mm. The same sign and a similar value are also found for the relative current helicity evaluated in real space based on the vertical components of magnetic field and current density. The modulus of the magnetic helicity spectrum shows a k(-11/3) power law at large wavenumbers, which implies a k(-5/3) spectrum for the modulus of the current helicity. A k(-5/3) spectrum is also obtained for the magnetic energy. The energy spectra evaluated separately from the horizontal and vertical fields agree for wavenumbers below 3 Mm(-1), corresponding to scales above 2 Mm. This gives some justification to our assumption of isotropy and places limits resulting from possible instrumental artifacts at small scales.

  • 1167029. Zhang, Hongqi
    et al.
    Brandenburg, Axel
    KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Sokoloff, D. D.
    Magnetic helicity and energy spectra of a solar active region2014In: Astrophysical Journal Letters, ISSN 2041-8205, Vol. 784, no 2, p. L45-Article in journal (Refereed)
    Abstract [en]

    We compute for the first time the magnetic helicity and energy spectra of the solar active regionNOAA 11158 during 2011 February 11-15 at 20 degrees southern heliographic latitude using observational photospheric vector magnetograms. We adopt the isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field. The sign of the magnetic helicity turns out to be predominantly positive at all wavenumbers. This sign is consistent with what is theoretically expected for the southern hemisphere. The magnetic helicity normalized to its theoretical maximum value, here referred to as relative helicity, is around 4% and strongest at intermediate wavenumbers of k approximate to 0.4Mm(-1), corresponding to a scale of 2 pi/k approximate to 16 Mm. The same sign and a similar value are also found for the relative current helicity evaluated in real space based on the vertical components of magnetic field and current density. The modulus of the magnetic helicity spectrum shows a k(-11/3) power law at large wavenumbers, which implies a k(-5/3) spectrum for the modulus of the current helicity. A k(-5/3) spectrum is also obtained for the magnetic energy. The energy spectra evaluated separately from the horizontal and vertical fields agree for wavenumbers below 3 Mm(-1), corresponding to scales above 2 Mm. This gives some justification to our assumption of isotropy and places limits resulting from possible instrumental artifacts at small scales.

  • 1167030.
    Zhang, Hongqiang
    Stockholm University, Faculty of Science, Department of Physics.
    Guiding of highly charged ions through insulating nanocapillaries2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis contains experimental work on guiding of highly charged ions through insulating nanocapillaries. We have studied the time evolution of angular distributions of transmitted ions under well defined initial conditions: already charged, as well as fully discharged nanocapillaries, by using a two-dimensional position sensitive Micro Channel Plate detector with a data acquisition system working in event mode. Time-dependent features in the ion-guiding properties have been found. For the initially discharged capillaries, a shift and broadening of transmitted angular distribution have been observed in the charge-up process. This is interpreted by the formation of charged patches downstream of the entrance patch. We have, with the help of a model calculation, quantitatively derived distinct charge patterns, resulting in the time evolution of the transmitted angular distributions. We show that all charge patches are maintained in the stationary state of transmission by the followed discharging and recharging measurements. For already charged nanocapillaries, a double peak structure in the angular distribution has been found, which is attributed to a memory effect and the re-arrangement of charge patches. When the tilt angle of the capillaries is changed, the existing charge patches from the previous tilt angle can affect the ion trajectories and the formation of new patches.

    The preliminary results of highly charged ions transmitted through muscovite mica capillaries of rhombic cross section are also presented in this thesis. We have shown the transmission profiles for various orientations of the rhombi. A rectangular shape of the transmission profile has been found. We have performed a simulation by considering the image force from the four sides of the rhombus. To our surprise, this effect gives an angular distribution that agrees well with the transmission profile obtained by the experiment.

  • 1167031.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Lanzhou University, China.
    Akram, Nadeem
    Stockholm University, Faculty of Science, Department of Physics.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Guiding and scattering of ions in transmission through mica nanocapillaries2016In: Physical review A, ISSN 2469-9926, Vol. 94, no 3, article id 032704Article in journal (Refereed)
    Abstract [en]

    The transition from guiding to scattering in the transmission of 70-keVNe(7+) through mica nanocapillaries of rhombic cross section is studied. Transmitted ions and neutrals are separated and their angular distributions are measured for various tilt angles of the capillaries with respect to the beam direction. The ions and neutrals have different angular profiles and different transmission dependences on tilt angle. The profiles of the transmitted ions are of rectangular shape while bananalike shapes appear for the neutrals. The time evolution measurements during charging up show a shift of the center of the ion angular distribution while that of the neutrals remains fixed. Trajectory simulations are performed by taking the image force and the Coulomb repulsive force from the deposited charge, as well as scattering from capillary walls into account. These show good agreement with the data and how the deposited or image charge deflects and shapes the ionic portion of the beam differently from the neutral part. The experimental separation of the ions from neutrals and their very different behaviors together with simulations gives us further insight into the mechanisms of guiding and scattering in transmission through nanocapillaries.

  • 1167032.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Akram, Nadeem
    Stockholm University, Faculty of Science, Department of Physics.
    Skog, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Soroka, Inna Leonidovna
    Stockholm University, Faculty of Science, Department of Physics.
    Trautmann, Christina
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Tailoring of keV-ion beams by image charge when transmitting through rhombic and rectangular shaped nanocapillariesIn: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114Article in journal (Refereed)
    Abstract [en]

    We report on an unexpected effect of tailoring transmission profiles of Ne7+-ions through nanocapillaries of rhombic and rectangular cross sections in mica. We find that capillaries of rhombic cross section produce rectangular shaped ion transmission profiles and, vice versa, capillaries of rectangular geometry give a rhombic beam shape. This shaping effect only occurs for transmitted ions and is absent for the small fraction of neutralized particles. The experimental findings and simulations of the projectile trajectories give clear evidence that the observed effect is due to the image forces experienced by the transmitting ions. This novel beam shaping mechanism suggests application for guiding, focusing, and shaping of ion beams.

  • 1167033.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Akram, Nadeem
    Stockholm University, Faculty of Science, Department of Physics.
    Soroka, I. L.
    Stockholm University, Faculty of Science, Department of Physics.
    Trautmann, C.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Transmission of highly charged ions through mica nanocapillaries of rhombic cross section2012In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 86, no 2, p. 022901-Article in journal (Refereed)
    Abstract [en]

    The angular distributions of Ne7+ ions transmitted at various kinetic energies of 7-70 keV through muscovite mica nanocapillaries of rhombic cross section are measured. It is found that the transmitted ion beams form a rectangular shape at tilt angles that are small compared to those given by the aspect ratio, i.e., the capillary geometrical opening angle. This shape is retained for all ion energies, but its size changes. The time evolution of the transmitted angular distributions shows that the characteristic profile occurs instantaneously and remains in the stationary state of the transmission, whereas it shifts with the increase of the accumulated incident charge. At tilt angles of the capillaries larger than their aspect ratio, the shape in the transmission profile gets distorted from the rectangle by the deposited charge. Combined with trajectory simulations we show the observed shaping effect is due to the image force seen by the ions, interplaying with a deflection by the deposited charge on the capillary walls.

  • 1167034.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Akram, Nadeem
    Stockholm University, Faculty of Science, Department of Physics.
    Soroka, Inna Leonidovna
    Stockholm University, Faculty of Science, Department of Physics.
    Trautmann, Christina
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Transmission of highly charged ions through mica nanocapillaries of rhombic cross sectionIn: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622Article in journal (Refereed)
    Abstract [en]

    The angular distributions of Ne7+-ions transmitted at various kinetic energies of 7 – 70 keV through muscovite mica nanocapillaries of rhombic cross section are measured. It is found that the transmitted ion beams form a rectangular shape at tilt angles, small compared to as given by the aspect ratio, i.e., the capillary geometrical opening angle. This shape is retained for all ion energies, but its size changes. The time evolution of the transmitted angular distributions shows that the characteristic profile occurs instantaneously and remains in the stationary state of the transmission, whereas it shifts with the increase of the accumulated incident charge. At tilt angles of the capillaries larger than their aspect ratio, the shape in the transmission profile gets distorted from the rectangle by the deposited charge. Combined with trajectory simulations we show the observed shaping effect is due to the image force seen by the ions, overplayed with a deflection by deposited charge, on the capillary walls.

  • 1167035.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics. Lanzhou University, China.
    Akram, Nadeem
    Stockholm University, Faculty of Science, Department of Physics.
    Trautmann, C.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Transmission profiles of ions through nano-capillaries of rectangular cross-section in mica2017In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, Vol. 406, p. 421-424Article in journal (Refereed)
    Abstract [en]

    We investigated transmission characteristics of Ne7+ ions through nanocapillaries of rectangular cross-section. The capillaries were produced by chemical etching of ion tracks in phlogopite mica. The two dimensional transmission profiles are rhombic when the capillaries are tilted at angles smaller than the geometrical opening angle given by the aspect ratio of the capillaries. For the angles larger than the geometrical opening angle with respect to the beam direction, the rhombic profile is degrading. Possible reasons for the degrading of the shapes by the deposited charge inside the capillaries are investigated and discussed.

  • 1167036.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    He, Z.B.
    Oleynikov, Peter
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Hovmöller, Sven Erik
    Stockholm University, Faculty of Science, Department of Physics.
    Zou, X.D.
    Kuo, K.H.
    A structure model for τ(μ) phase in Al-Cr-Si alloys deduced from λ phase by the strong reflections approach2006In: Acta Crystallographica Section B: Structural Science, ISSN 0108-7681, E-ISSN 1600-5740, Vol. 62, no 1, p. 16-25Article in journal (Refereed)
    Abstract [en]

    There are very obvious common features in the electron diffraction patterns of the λ and τ(μ) phases in the Al–Cr–Si system. The positions of the strong reflections and their intensity distributions are similar for the two structures. The relation of the reciprocal lattices of the λ and τ(μ) phases is studied. By applying the strong-reflections approach, the structure factors of τ(μ) are deduced from the corresponding structure factors of the known λ phase. Rules for selecting reflections for the strong-reflections approach are described. Similar to that of λ, the structure of τ(μ) contains six layers stacked along the c axis in each unit cell. There are 752 atoms in each unit cell, 53 of them are unique. The corresponding composition of the τ(μ) model is Al3.82  −  xCrSix. Simulated electron diffraction patterns from the structure model are in good agreement with the experimental ones. The arrangement of interpenetrated icosahedral clusters in the τ(μ) phase is discussed.

  • 1167037.
    Zhang, Hongqiang Q.
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Akram, Nadeem
    Stockholm University, Faculty of Science, Department of Physics.
    Skog, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Soroka, I. L.
    Stockholm University, Faculty of Science, Department of Physics.
    Trautmann, C.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Tailoring of keV-Ion Beams by Image Charge when Transmitting through Rhombic and Rectangular Shaped Nanocapillaries2012In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 108, no 19, p. 193202-Article in journal (Refereed)
    Abstract [en]

    We report on an unexpected effect of tailoring transmission profiles of Ne7+ ions through nanocapillaries of rhombic and rectangular cross sections in mica. We find that capillaries of rhombic cross sections produce rectangular shaped ion transmission profiles and, vice versa, that capillaries of rectangular geometry give a rhombic beam shape. This shaping effect only occurs for transmitted ions and is absent for the small fraction of neutralized particles. The experimental findings and simulations of the projectile trajectories give clear evidence that the observed effect is due to the image forces experienced by the transmitting ions. This novel beam shaping mechanism suggests applications for the guiding, focusing, and shaping of ion beams.

  • 1167038.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Skog, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Dynamics of Guiding Highly Charged Ions through SiO2 Nanocapillaries2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 82, no 052901Article in journal (Refereed)
    Abstract [en]

    Time evolution of angular distributions of transmitted ions through SiO2 nanocapillaries wasmeasured under defined initial conditions: already charged, as well as fully dischargedcapillaries. We find distinct charge patterns and describe them quantitatively with the help of amodel calculation. This results in a pattern of a few number of charge patches, guiding ions inthe stationary state of transmission. For the already charged capillary membrane, we show a“memory effect” in the form of a double peak structure in the transmitted angulardistributions. The time evolution of these structures reflects charge relaxation andrearrangement of the charge patches. The re-arrangement of the charge patches is much fasterthan the discharge, suggesting that the charge relaxation inside the capillaries can be drivenby the incident charges, such as a Frenkel-Poole process.

  • 1167039.
    Zhang, Hongqiang
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Skog, Patrik
    Stockholm University, Faculty of Science, Department of Physics.
    Schuch, Reinhold
    Stockholm University, Faculty of Science, Department of Physics.
    Guiding of slow highly charged ions through insulating nano-capillaries2009In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 163, no 1Article in journal (Refereed)
    Abstract [en]

    The guiding of highly charged ions through SiO2 nano-capillaries has been investigated by our group, using 7 keV Ne7+-ions. We studied in particular the transmission of ions incident at angles greater than the angle given by the capillary aspect ratio as a function of charge incident on the capillary membrane. In this report we show the re-arrangement of charge patches inside the capillary by observing the evolution of the two-dimensional angular distributions of the transmitted ions.

  • 1167040.
    Zhang, Hongtao
    et al.
    Univ Waterloo, Dept Mech & Mechatron Engn, Lab Fuel Cell & Green Energy RD&D 20 20, Waterloo, ON N2L 3G1, Canada.;Univ Waterloo, Dept Appl Math, Waterloo, ON N2L 3G1, Canada..
    Li, Xianguo
    Univ Waterloo, Dept Mech & Mechatron Engn, Lab Fuel Cell & Green Energy RD&D 20 20, Waterloo, ON N2L 3G1, Canada..
    Liu, Xinzhi
    Univ Waterloo, Dept Appl Math, Waterloo, ON N2L 3G1, Canada..
    Yan, Jinyue
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Energy Processes. Malardalen Univ, Sch Sustainable Dev Soc & Technol, S-72123 Vasteras, Sweden..
    Enhancing fuel cell durability for fuel cell plug-in hybrid electric vehicles through strategic power management2019In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 241, p. 483-490Article in journal (Refereed)
    Abstract [en]

    Fuel cell plug-in hybrid electric vehicles (FC-PHEVs) can have extended range while utilizing cheap grid electricity, but has poor durability of onboard fuel cells due to dynamic loading. In this study, fuel cell durability is enhanced significantly for a novel configuration of FC-PHEVs with three fuel cell stacks through strategic power management by making each fuel cell stack work only at a fixed operating point (i.e., constant output power) and by shortening its active time (operation) via on-off switching control. A hysteresis control strategy of power management is designed to make the active time evenly distributed over the three fuel cell stacks and to reduce the number of on-off switching. The results indicate that the durability of the onboard fuel cells can be increased 11.8, 4.8 and 6.9 times, respectively, for an urban, highway and a combined urban-highway driving cycle. This enhanced fuel cell durability is derived from the fact that the average power demand of real-time driving cycles is only a fraction of the maximum power that FC-PHEVs could provide, and substantially increased durability can be used to reduce the over-design, hence the cost, of fuel cells.

  • 1167041. Zhang, Hongtao
    et al.
    Yan, Haixue
    Eriksson, Mirva
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Shen, Zhijian
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    The grain size effect on the properties of Aurivillius phase Bi3.15Nd0.85Ti3O12 ferroelectric ceramics2009In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 20, no 38, p. 385708/1-385708/5Article in journal (Refereed)
  • 1167042. Zhang, Hongtao
    et al.
    Yan, Haixue
    Zhang, Xiaodong
    Reece, Mike J.
    Liu, Jing
    Shen, Zhijian
    Kan, Yanmei
    Wang, Peiling
    The effect of texture on the properties of Bi3.15Nd0.85Ti3O12 ceramics prepared by spark plasma sintering.2008In: Materials Science & Engineering, A: Structural Materials: Properties, Microstructure and Processing, Vol. 1-2, no A475, p. 92-95Article in journal (Refereed)
  • 1167043. Zhang, Hongwei
    et al.
    Gandin, Charles-Andre
    Ben Hamouda, Haithem
    Tourret, Damien
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    He, Jicheng
    Prediction of Solidification Paths for Fe-C-Cr Alloys by a Multiphase Segregation Model Coupled to Thermodynamic Equilibrium Calculations2010In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 50, no 12, p. 1859-1866Article in journal (Refereed)
    Abstract [en]

    A microsegregation model for the solidification of multicomponent alloys is developed It couples the volume-averaged conservation equations for total mass solute mass and energy assuming a uniform temperature The diffusion in the liquid and solid phases the growth kinetics of the solidifying microstructures and the velocity of the solid/liquid and solid/solid phase interfaces are considered in the model Equilibrium between phases is taken into account and computed using dedicated thermodynamic software The thermodynamic properties and their evolutions during solidification are directly retrieved from a database Illustration is provided by the solidification of a Fe-C-Cr alloy The occurrence of the recalescence due to the growth of the microstructure and the progress of solidification are predicted The solidification behavior near to recalescence is evaluated By adjusting the cooling intensity and the solute diffusivities extreme approximations are retrieved The model shows potentials to be coupled with a macrosegregation model for application to the solidification of multicomponent alloys

  • 1167044. Zhang, Hongwei
    et al.
    Liu, Qiang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Shibata, Hiroyuki
    Wang, Qiang
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    He, Jicheng
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Partial Equilibrium Prediction of Solidification and Carbide Precipitation in Ti-added High Cr Cast Irons2014In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 54, no 2, p. 374-383Article in journal (Refereed)
    Abstract [en]

    Carbide precipitation and eutectic phase transformation during solidification of Fe-C-Cr-Ti-Mn-Mo-Ni-Si Ti-added high-chromium cast irons (HCCIs) were studied numerically and experimentally by the help of Partial Equilibrium approximation, DSC thermal analyses and EDX analyses. The main carbides formed during the solidification are distinguished as MC, primary M7C3 and eutectic M7C3 from their distinguished constitution, while other researchers didn't distinguish the primary and eutectic M7C3 carbide. Through comparing the prediction of Partial Equilibrium approximation with DSC thermal analysis measurement, the precipitation sequence of the eutectic structure in HCCIs is clarified to follow the sequence of FCC prior to the eutectic M7C3, although they were usually expected to precipitate simultaneously. The hardness index of the HCCIs is evaluated quantatively by summation of the contributions of the Vickers hardness of MC, primary M7C3 and eutectic M7C3 carbides with predicted precipitation amount and composition / constitution. The effects of C, Ti and Cr contents on the precipitation sequence, the amount and the composition of carbides as well as the hardness of the HCCIs are discussed deeply. Finally, the validity of Partial Equilibrium approximation is shown in prediction of the solidification in multicomponent system with large amount of precipitated carbides.

  • 1167045. Zhang, Hongwei
    et al.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gandin, Charles-Andre
    He, Jicheng
    Prediction of Carbide Precipitation Using Partial Equilibrium Approximation in Fe-C-V-W-Cr-Mo High Speed Steels2013In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, no 3, p. 493-501Article in journal (Refereed)
    Abstract [en]

    In Fe-C-V-W-Cr-Mo high speed steels, the nature of carbides during the solidification are discussed as a function of C, V and W content by the help of Partial Equilibrium (PE) approximation and thermodynamic calculations. The results show that the solidification path and carbide precipitation can be reasonably predicted by the Partial Equilibrium approximation for cooling rate lower than 10-13 K min(-1). From the viewpoint of hardness control by carbides, it is found that among the main carbides MC, M6C and M7C3, the increase of C favours the formation of MC, M7C3 but decreases the hardness of M7C3 by increasing the Fe content in it. Meanwhile, the increase of V only increases the amount of MC and V content therein, and the increase of W largely increases the amount of M6C and W content in it. As a result, the addition of V and W improves the hardness of MC and M6C carbides.

  • 1167046. Zhang, Hongwei
    et al.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Lei, Hong
    He, Jicheng
    Restrictions of Physical Properties on Solidification Microstructures of Al-based Binary Alloys by Cellular Automaton2010In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 50, no 12, p. 1835-1842Article in journal (Refereed)
    Abstract [en]

    The solidification microstructure evolution and the Columnar to Equiaxed Transition (CET) during Al-Si and Al-Cu binary alloy solidification processes are analyzed by the help of Cellular Automaton-Finite Difference (CA-FD) model The effects of the physical properties except the effects of the nucleation parameters and the operation parameters on the cooling curves the dendrite growth the solidification morphologies and the CET of the Al-Si and Al-Cu binary alloys are emphatically discussed Results show that the solidification morphologies are internally influenced by the physical properties related to the dendrite tip growth kinetics Besides the solute diffusivity in liquid D-L and the growth restriction parameter Q=mC(o)(k(S/L)-1) the Gibbs-Thomson coefficient Gamma shows a great effect on dendrite tip growth rate Their effects on the dendrite tip kinetics are ordered as m(k(S/L)-1)>Gamma>D-L The growth rate can be predicted efficiently by the present simplified expression based on GGAN model combining several physical parameters and the local under-cooling which clearly shows the physical meaning of the constant coefficients in the simplified expression based on KGT model The equiaxed ratio related to the solidification morphologies can also be evaluated as a function of those physical properties

  • 1167047. Zhang, Hongwei
    et al.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Wu, Rangqiong
    Wang, Qiang
    He, Jicheng
    Prediction of Solidification Microstructure and Columnar-to-equiaxed Transition of Al-Si Alloy by Two-dimensional Cellular Automaton with "Decentred Square" Growth Algorithm2009In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 49, no 7, p. 1000-1009Article in journal (Refereed)
    Abstract [en]

    A Cellular Automaton (CA)-Finite Difference (FD) coupling model was developed to analyze the evolution of solidification microstructure and the columnar-to-equiaxed transition (CET) in AI-Si alloy. Kobayashi's microsegregation equation was adopted to describe the solute diffusion in solid phase, and a "decentred square" growth algorithm with coordinate transformation was performed to describe the grain growth and the entrapment of neighbor cells. Through the examination on the effects of operation parameters and nucleation parameters on solidification morphologies, it was found that the length of columnar grains is controlled by the dendrite tip growth kinetics, and that the width of columnar grains is controlled by the implicit relationship between nucleation density and cooling rate at ingot surface. It was also found that the size of equiaxed grains is controlled by the competition of the nucleation and the grain growth. With the controllability of nucleation density in the bulk of liquid for equiaxed grain size, the nucleant and the nucleation density in actual AI-Si alloy were estimated. Both of the CET criteria based on the solidification path by CA-FD coupling model and the one based on the curves of critical temperature gradient conditions by Hunt's model were strongly dependent on nucleation undercooling and Si concentration. A good agreement was obtained between these two.

  • 1167048. Zhang, Hongwei
    et al.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Xing, Wei
    Wang, Aili
    He, Jicheng
    Influences of Flow Intensity, Cooling Rate and Nucleation Density at Ingot Surface on Deflective Growth of Dendrites for Al-based Alloy2009In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 49, no 7, p. 1010-1018Article in journal (Refereed)
    Abstract [en]

    The dendrite tip growth kinetics in the flow field and the decentred quadrilateral growth algorithm for describing the evolution of grain growth are combined in Cellular Automaton model to predict the deflective growth of dendrites inclined toward upstream direction. The influences of flow intensity, cooling rate (or solidification rate), nucleation density at ingot surface on the deflective growth of dendrites are discussed. The increase of flow intensity dominantly forces the dendrites to grow in upstream direction; on the contrary, the increases of nucleation density at ingot surface and cooling rate suppress slightly this deflective growth. The relations predicted among deflection angle, flow intensity and solidification rate for AI-Si alloy and Al-Cu alloy show the same tendency as that in Okano et al.'s empirical expression deduced from experiments on steel. The deflection angle predicted for Al-Cu alloy fits well with previous experimental results.

  • 1167049.
    Zhang, Hongxia
    Kristianstad University, School of Teacher Education.
    A study on ESL writing anxiety among Chinese English majors: Causes, effects and coping strategies for ESL writing anxiety2011Independent thesis Advanced level (degree of Master (One Year)), 60 credits / 90 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to measure the level of ESL writing anxiety experienced by Chinese English majors. The effects of ESL writing anxiety on English writing performance, the students’ perception of the main causes of ESL writing anxiety and their learning style preferences in ESL writing class were also examined, which provided pedagogical implications of successful learning and teaching strategies for reducing ESL writing anxiety. This study was based on quantitative research and three questionnaires were used to collect data. The results of the SLWAI showed that there is a high level of ESL writing anxiety among Chinese English majors, and the Cognitive Anxiety is the most common type of ESL writing anxiety. The differences in the level of English writing anxiety between the groups of freshmen and sophomores reached the level of statistical significance. The sophomores were found to suffer significantly higher levels of English writing anxiety than the freshmen. Correlation analysis results suggested a negative relationship between measure of ESL writing anxiety and measures of writing performance (course grade and timed writing grade). An in-depth analysis of the causes of ESL writing anxiety revealed that linguistic difficulties, insufficient writing practice, fear of tests (TEM), lack of topical knowledge and low self-confidence in writing performance constitute the main sources of ESL writing anxiety experienced by Chinese English majors. Furthermore, suggestions on learning and teaching strategies for reducing ESL writing anxiety were provided on the basis of the acknowledge of sources of ESL writing anxiety and students’ learning style preferences in ESL writing class.

  • 1167050.
    Zhang, Hongxia
    Kristianstad University, School of Teacher Education.
    Who dominates the class, boys or girls?: A study on gender differences in English classroom talk in a Swedish upper secondary school2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
23338233392334023341233422334323344 1167001 - 1167050 of 1200544
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf