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ebru  yildirim

    ebru yildirim

    York University, Işletme, Graduate Student
    • merhaba, dünyayı ve insanları seven herkese selamlaredit
    Research Interests:
    In this study, the productivity and efficiency analyses have been conducted considering the 1997-2007 periods at three firms operating in sugar industry, two of them are SOEs (state-owned enterprises) and the other is a POE... more
    In this study, the productivity and efficiency analyses have been conducted considering the 1997-2007 periods at three firms operating in sugar industry, two of them are SOEs (state-owned enterprises) and the other is a POE (privated-owned enterprise). Labor indices are used in the productivity analyses and Data Envelopment Analysis in the efficiency measurements. Data Envelopment Analysis, which is a method
    ABSTRACT The effects of boron carbide (B4C) additions on characteristic of diamond impregnated Fe-Co-Cu matrix composites have been investigated using powder metallurgy (PM) method. For this purpose, samples of Fe-(30-60)wt. % Cu–20 wt.... more
    ABSTRACT The effects of boron carbide (B4C) additions on characteristic of diamond impregnated Fe-Co-Cu matrix composites have been investigated using powder metallurgy (PM) method. For this purpose, samples of Fe-(30-60)wt. % Cu–20 wt. %Co alloys and1wt. % B4C additions of its matrix were processed by cold pressing at 350 MPa, followed by sintering at 1100°C. Microstructural examination, hardness and wear tests were performed.The microstructure of Fe–Cu–Co alloys was very sensitive to the Cu content and pore closure took place with increasing the Cu content.In addition, the addition of B4C particles increased Fe–Cu-Co hardness about 44% compared to samples without B4C particles. The experimental results showed that alloy Fe–60 wt. % Cu–20 wt. %Co-1 wt. % B4C presented the best results for use in diamond cutting tools.
    In this research, residues of certain veterinary drugs (florfenicol (FF) and florfenicol amine (FFA)) were screened in natural fish, sediment, and seawater samples of the Aegean Sea, while only chloramphenicol (CAP) was searched for in... more
    In this research, residues of certain veterinary drugs (florfenicol (FF) and florfenicol amine (FFA)) were screened in natural fish, sediment, and seawater samples of the Aegean Sea, while only chloramphenicol (CAP) was searched for in the sediment. Samples were collected from fish farming cages in selected coordinates (Bodrum, Salihli Region, Turkey) on September, October 2011 and March, April 2012. Method validation and analyses were carried out by HPLC method. For FF; LOD values were 25.11 ppb for sea water, 27.07 ppb for sediment as well as 38.16 and 37.95 ppb for Mullus barbatus and Oblada tnelanura fish samples. FFA value for Mullus barbatus was 39.60 ppb, respectively. For CAP in sediment samples, LOD values were found as 53.59 ppb. In 4 different sampling areas (A, B, C, D), the lowest temperature was recorded as 14 degrees C in March 2012 but the highest was 28.3 degrees C in October 2011; the lowest dissolved oxygen (mg/L) values were detected in March 2012 (from 6.05 to 6...
    The aim of this study was to investigate the effects of magnesium sulphate (MgSO4) on some biochemical and hematological parameters, lipid peroxidation, and antioxidant enzymes in pregnant rat model of preeclampsia induced by... more
    The aim of this study was to investigate the effects of magnesium sulphate (MgSO4) on some biochemical and hematological parameters, lipid peroxidation, and antioxidant enzymes in pregnant rat model of preeclampsia induced by Lw-nitro-L-arginine methyl ester (L-NAME). Thirty two pregnant Sprague-Dawley rats were divided into 4 equal groups as control, L-NAME (50 mg/kg bw/day), MgSO4 (600 mg/kg bw/day) or L-NAME + MgSO4 (1-4) given groups on the 11th day of the pregnancy in their drinking water. The increased blood pressure (BP) was detected on the 12th and 19th days of pregnancy. Blood samples were collected on the 19th day to determine blood oxidative status, some biochemical and hematological parameters. LNAME decreased erythrocyte superoxide dismutase activity, plasma total protein level and increased erythrocyte catalase and glutathion peroxidase activities, BP, plasma malondialdehyde, cholesterol and triglyceride levels, alkaline phophatase activity and white blood cell counts ...
    The aim of this study was to investigate the effects of Ginkgo biloba extract (EGb 761) on oxidative stress and the histopathological changes in brain tissues of mice exposed to fluoride administration. A total of 24 mice were divided... more
    The aim of this study was to investigate the effects of Ginkgo biloba extract (EGb 761) on oxidative stress and the histopathological changes in brain tissues of mice exposed to fluoride administration. A total of 24 mice were divided into 4 groups as control, EGb 761, fluoride and fluoride+EGb 761, with 6 mice in each group. Control group received drinking water, fluoride group received 50 mg/L fluoride in drinking water, fluoride+EGb 761 group was given 50 mg/L fluoride in drinking water and 20 mg/kg EGb 761 orally by gavage, and EGb 761 group was given only 20 mg/kg EGb 761 orally by gavage for 30 days. At the end of the experimental period, the levels of malondialdehyde (MBA) and glutathione (GSH) as well as' the activities of superoxide dismutase (SOD) and catalase (CAT) were detected, and histopathological examination was conducted in the brain of mice. The results showed that the levels of MDA, GSH, and the activities of SOD and CAT in fluoride group were statistically hi...
    ... RICHARD J. McCOY', MICHAEL A. JOHNSON' and MICHAEL SHEPPARD'J ... tions 103, 121 and 125), known to be important to the function of the adenovirus protease, and con-served in other mammalian adenoviruses examined... more
    ... RICHARD J. McCOY', MICHAEL A. JOHNSON' and MICHAEL SHEPPARD'J ... tions 103, 121 and 125), known to be important to the function of the adenovirus protease, and con-served in other mammalian adenoviruses examined (Webster et a/., 1993, Rancourt et a/, 1994) sup ...
    Research Interests:
    This study investigated effects of dietary supplementation with vitamin C, vitamin E on performance, biochemical parameters, and oxidative stress induced by copper toxicity in broilers. A total of 240, 1-day-old, broilers were assigned to... more
    This study investigated effects of dietary supplementation with vitamin C, vitamin E on performance, biochemical parameters, and oxidative stress induced by copper toxicity in broilers. A total of 240, 1-day-old, broilers were assigned to eight groups with three replicates of 10 chicks each. The groups were fed on the following diets: control (basal diet), vitamin C (250 mg/kg diet), vitamin E (250 mg/kg diet), vitamin C + vitamin E (250 mg/kg + 250 mg/kg diet), and copper (300 mg/kg diet) alone or in combination with the corresponding vitamins. At the 6th week, the body weights of broilers were decreased in copper, copper + vitamin E, and copper + vitamin C + vitamin E groups compared to control. The feed conversion ratio was poor in copper group. Plasma aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase activities, iron, copper concentrations, and erythrocyte malondialdehyde were increased; plasma vitamin A and C concentrations and erythrocyte superoxide dismutase were decreased in copper group compared to control. Glutathione peroxidase, vitamin C, and iron levels were increased; aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and copper levels were decreased in copper + vitamin C group, while superoxide dismutase, glutathione peroxidase, and vitamin E concentrations were increased; aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase were decreased in copper with vitamin E group compared to copper group. The vitamin C concentrations were increased; copper, uric acid, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and malondialdehyde were decreased in copper + vitamin C + vitamin E group compared to copper group. To conclude, copper caused oxidative stress in broilers. The combination of vitamin C and vitamin E addition might alleviate the harmful effects of copper as demonstrated by decreased lipid peroxidation and hepatic enzymes.
    The aim of this study is to determine the effect of levamisole and levamisole-trichlorfon combination on isolated sheep trachea. Contraction was achieved with levamisole concentrations (10(-8)-10(-3) M) on tracheal strips of adult sheep... more
    The aim of this study is to determine the effect of levamisole and levamisole-trichlorfon combination on isolated sheep trachea. Contraction was achieved with levamisole concentrations (10(-8)-10(-3) M) on tracheal strips of adult sheep (> 1 year of age). Pretreatment with trichlorfon (10(-7) M)-levamisole (10(-7) M) decreased the pD2 and E(max) of Ach when compared to levamisole pretreatment (p < or = 0.01). Pretreatment with levamisole (10(-7) M), decreased the E(max) (p < or = 0.01) and pD2 (p < 0.05) of bethanechol concentrations (10(-8)-10(-3) M) significantly. Pretreatment with atropine (10(-6) M) decreased the E(max) of levamisole (10(-4) M) significantly (p < 0.05). To conclude, levamisole acted mainly on the muscarinic receptors of the sheep trachea and this effect was partly inhibited by atropine. Adverse interaction was present between levamisole and trichlorfon.
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