Browsing by Author "Yaman, B"

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    Wear Behavior of Fe-C-Cr Based Hardfacing Alloys Dependent on Ferrovanadium and Ferrotungsten Addition
    Kapali, G; Sahin, S; Yüksel, N; Sargin, F; Yaman, B
    The aim of this study is to investigate the effect of vanadium and tungsten on wear behavior of Fe-C-Cr based hardfacing alloys. The wear behavior of hardfacing layers was determined by dry sand/rubber wheel abrasion tests according to ASTM G-65. The results of the abrasion tests were interpreted by metallographic examinations, SEM and EDX analyses as well as hardness measurements. According to the results of the experimental studies, the effect of W and V addition was discussed.
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    Hyperbaric oxygen treatment in the experimental spinal cord injury model
    Yaman, O; Yaman, B; Aydin, F; Var, A; Temiz, C
    BACKGROUND CONTEXT: Spinal cord trauma is a major cause of mortality and morbidity. Although no known treatment for spinal cord injury exists, a limited number of effective treatment modalities and procedures are available that improve secondary injury. Hyperbaric oxygen (HBO) treatment has been used to assist in neurologic recovery after cranial injury or ischemic stroke. PURPOSE: To report the findings on the effectiveness of HBO treatment on rats with experimental traumatic spinal cord injury. Improvement was evaluated through motor strength assessment and nitrite level assay testing. STUDY DESIGN: We randomly distributed 40 rats among 5 groups of 8 rats each: sham incurable trauma, induced trauma, HBO treatment begun at the 1st hour, HBO treatment begun at the 6th hour, and HBO treatment begun at the 24th hour. METHOD: The HBO treatment was administered to rats in three of the groups and conducted in two 90-minute sessions, under an absolute atmospheric pressure of 2.4 at 100% oxygen for 5 days. In the motor strength evaluations, all the rats were observed during the inclined plane test and clinical motor examination on the first, third, and fifth days. In addition, the nitrite levels of spinal cord tissues on the sixth day were also studied. RESULTS: Results from the inclined plane levels and motor strength test from all the three groups undergoing HBO treatment were higher than those from Group 2. It was also determined that early HBO treatment resulted in higher recovery rates (groups 3 and 4). The highest levels were seen in the group in which the HBO treatments were started in the first hour (Group 3). It was noted that nitrite levels of rats in the group exposed to trauma increased, compared with the sham group, but increased levels also diminished after HBO treatments. Again, the greatest decrease in nitrite levels was evident in the group where the HBO treatment was started the earliest (Group 3). CONCLUSIONS: Prompt HBO treatment after trauma significantly contributed to the clinical, histopathologic, and biochemical recovery of the rats. (C) 2014 Elsevier Inc. All rights reserved.
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    A Retrospective Multicenter Evaluation of Cutaneous Melanomas in Turkey
    Gamsizkan, M; Yilmaz, I; Buyukbabani, N; Demirkesen, C; Demiriz, M; Cetin, ED; Ince, U; Akalin, T; Demirkan, NC; Lebe, B; Erdem, O; Gokoz, O; Sakiz, D; Demireli, PT; Astarci, HM; Adim, SB; Zemheri, IE; Acikalin, A; Yaman, B; Aydin, O; Bassorgun, CI
    Background: We defined melanoma distribution in a large series of Turkish patients and evaluated the prognostic parameters of melanomas. Materials and Methods: A total of 1574 patients' data was retrospectively collected at 18 centers in Turkey. Demographic characteristics were questioned and noted. Prognostic parametres were evaluated based on sentinel lymph node involvement. Results: Mean age was 56.7 (4-99) years. While 844 (53.6%) cases were male, 730 (46.4%) cases were female. One thousand four hundred forty-seven (92%) cases were invasive melanoma and 127 (8%) cases were in-situ melanoma. The most common histopathological form was the superficial spreading melanoma (SSM) which was found in 549 patients (37.9%). It was followed by nodular melanoma in 379 (26.2%), acral lentiginous melanoma (ALM) in 191 (13.2%) and lentigo maligna melanoma in 132 (9.1%), respectively. On univariate analysis, lymphovascular invasion (p<0.001), tumor thickness (p<0.001), histopathological subtype (p<0.001), Clark level (p=0.001), ulceration (p<0.001), >= 6/mm(2) mitosis (p=0.005), satellite formation (p=0.001) and gender (p=0.03) were found to be associated with sentinel lymph node positivity. Regression was associated with sentinel lymph node negativity (p=0.017). According to multivariate analysis, lymphovascular invasion and tumor thickness were significant independent predictive factors of SLN positivity. Patient age, tumor localization, precursor lesions, lymphocytic infiltration and neurotropism were not related with sentinel lymph node involvement. Conclusions: In this retrospective analysis, it was found that the prevalence of SSM is at a lower rate while the prevalence of ALM is at a higher rate when compared to western countries. According to Breslow index; most of the melanoma lesions' thickness were greater than 2 mm, corresponding Clark IV. Vascular invasion and tumor thickness are the most important factors for sentinel lymph node involvement.