Advanced Electrodes for Solid Acid Fuel Cells by Platinum Deposition on CsH_(2)PO_4

We demonstrate cathodes for solid acid fuel cells fabricated by vapor deposition of platinum from the metalorganic precursor Pt(acac)_2 on the solid acid CsH_(2)PO_4 at 210 °C. A network of platinum nanoparticles with diameters of 2−4 nm serves as both the oxygen reduction catalyst and the electronic conductor in the electrode. Electrodes with a platinum content of 1.75 mg/cm^2 are more active for oxygen reduction than previously reported electrodes with a platinum content of 7.5 mg/cm^2. Electrodes containing <1.75 mg/cm^2 of platinum show significantly reduced catalytic activity and increased ohmic resistance indicative of a highly discontinuous catalytic-electronic platinum network

Hard Superconductivity of a Soft Metal in the Quantum Regime

Superconductivity is inevitably suppressed in reduced dimensionality. Questions of how thin superconducting wires or films can be before they lose their superconducting properties have important technological ramifications and go to the heart of understanding coherence and robustness of the superconducting state in quantum-confined geometries. Here, we exploit quantum confinement of itinerant electrons in a soft metal to stabilize superconductors with lateral dimensions of the order of a few millimeters and vertical dimensions of only a few atomic layers. These extremely thin superconductors show no indication of defect- or fluctuation-driven suppression of superconductivity and sustain supercurrents of up to 10% of the depairing current density. The extreme hardness of the critical state is attributed to quantum trapping of vortices. This study paints a conceptually appealing, elegant picture of a model nanoscale superconductor with calculable critical state properties. It indicates the intriguing possibility of exploiting robust superconductivity at the nanoscale.Comment: 15 pages, 4 figures, submitted to Nature Physic

Supersymmetry and the relationship between a class of singular potentials in arbitrary dimensions

The eigenvalues of the potentials $V_{1}(r)=\frac{A_{1}}{r}+\frac{A_{2}}{r^{2}}+\frac{A_{3}}{r^{3}}+\frac{A_{4 }}{r^{4}}$ and $V_{2}(r)=B_{1}r^{2}+\frac{B_{2}}{r^{2}}+\frac{B_{3}}{r^{4}}+\frac{B_{4}}{r^ {6}}$, and of the special cases of these potentials such as the Kratzer and Goldman-Krivchenkov potentials, are obtained in N-dimensional space. The explicit dependence of these potentials in higher-dimensional space is discussed, which have not been previously covered.Comment: 13 pages article in LaTEX (uses standard article.sty). Please check "http://www1.gantep.edu.tr/~ozer" for other studies of Nuclear Physics Group at University of Gaziante

A novel approach for rapid screening of mitochondrial D310 polymorphism

BACKGROUND: Mutations in the mitochondrial DNA (mtDNA) have been reported in a wide variety of human neoplasms. A polynucleotide tract extending from 303 to 315 nucleotide positions (D310) within the non-coding region of mtDNA has been identified as a mutational hotspot of primary tumors. This region consists of two polycytosine stretches interrupted by a thymidine nucleotide. The number of cytosines at the first and second stretches are 7 and 5 respectively, according to the GeneBank sequence. The first stretch exhibits a polymorphic length variation (6-C to 9-C) among individuals and has been investigated in many cancer types. Large-scale studies are needed to clarify the relationship between cytosine number and cancer development/progression. However, time and money consuming methods such as radioactivity-based gel electrophoresis and sequencing, are not appropriate for the determination of this polymorphism for large case-control studies. In this study, we conducted a rapid RFLP analysis using a restriction enzyme, BsaXI, for the single step simple determination of 7-C carriers at the first stretch in D310 region. METHODS: 25 colorectal cancer patients, 25 breast cancer patients and 41 healthy individuals were enrolled into the study. PCR amplification followed by restriction enzyme digestion of D310 region was performed for RFLP analysis. Digestion products were analysed by agarose gel electrophoresis. Sequencing was also applied to samples in order to confirm the RFLP data. RESULTS: Samples containing 7-C at first stretch of D310 region were successfully determined by the BsaXI RFLP method. Heteroplasmy and homoplasmy for 7-C content was also determined as evidenced by direct sequencing. Forty-one percent of the studied samples were found to be BsaXI positive. Furthermore, BsaXI status of colorectal cancer samples were significantly different from that of healthy individuals. CONCLUSION: In conclusion, BsaXI RFLP analysis is a simple and rapid approach for the single step determination of D310 polymorphism of mitochondrial DNA. This method allows the evaluation of a significant proportion of samples without the need for sequencing- and/or radioactivity-based techniques

Enver Gökçe ve Çit Köyündeki yaşamı

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2015.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by Emiroğlu, Kudret

Ciddi aterosklerozu bulunan farklı yaş gruplarına ait hastalarda görülen gen polimorfizmlerinin karşılaştırılması

Amaç: Bu çalışma, koroner arter hastalığı bulunan bir grup hastada anjiyotensin dönüştürücü enzim, faktör V, endotelyal nitrik oksit sentaz ve interlökin-6 genetik polimorfızmlerinin birlikteliğini değerlendirmektedir. Gereç ve Yöntem : Hastalar, biri kontrol ve diğer ikisi çalışma grubu 1 ve çalışma grubu 2 olarak, 20'ser kişiden oluşan 3 gruba ayrıldılar. Grup l'e ait hastalar, 40 yasın altında ve ciddi koroner arter hastalığı bulunan hastalardan oluştu. Grup 2'ye ait hastalar, 70 yasın üstünde ve ciddi koroner arter hastalığı olan kişilerden oluştu. Kontrol grubundaki hastalar, 70 yasın üzerinde ve normal koroner arterlere sahip olan kişilerden oluştu. Gruplar arasında anjiyotensin dönüştürücü enzim, faktör V, endotelyal nitrik oksit sentaz ve intcrlökin-6 gen polimorfızmlerine ait allel sıklıkları karşılaştırıldı. Bulgular: Grup 1 ve Grup 2'deki hastalarda tespit edilen, anjiyotensin dönüştürücü enzim, faktör V, endotelyal nitrik oksit sentaz ve interlökin-6 gen polimorfizmlerine ait allel sıklıkları kontrol grubundaki deneklerden elde edilen allel sıklıklarından anlamlı derecede farklı bulunmadı. Faktör V Leiden "A" allel sıklığı, Grup 1 'e ait hastalarda, kontrol grubuna ait hastalardan anlamlı olarak daha yüksek sıklıkta bulundu. Sonuç: Bu çalışmada gerek genç gerekse yaslı kişilerde, anjiyotensin dönüştürücü enzim, faktör V, endotelyal nitrik oksit sentaz ve interlökin-6 genetik polimorfızmleri, koroner arter hastalığı ile bağlantılı bulunmadı. Ancak genç hastalarda, faktör V Leiden "A" allel sıklığı kontrol grubuna ait hastalardan anlamlı olarak daha yüksekti. Bu nedenle, gençlerde görülen koroner arter hastalıklarında protrombotik risk faktörlerinin etiyoloji-de rol aldıkları düşünülebilir.Purpose: To evaluate the association of genetic polymorphisms of angiotensin converting enzyme, factor V, endothelial nitric oxide synthase, and interleukinr&ouml; in a group of patients that have coronary artery disease. Materials and Methods: Patients were assigned into three groups of 20, one being the control and the other two being the study groups 1 and 2. Group 1 consisted of patients less than 40 years of age with severe coronary artery disease. Group 2 consisted of patients older than 70 years of age with severe coronary artery disease. The control group consisted of patients over 70 years of age with normal coronary arteries. Allele frequencies for angiotensin converting enzyme, factor V, endothelial nitric oxide synthase, and interleukin-6 gene polymorphisms were compared. Results: The allele frequencies for angiotensin converting enzyme, endothelial nitric oxide synthase, and interleukin-6 in groups 1 and 2 were not found to be significantly different from those of the control group. Factor V Leiden 'A' allele frequency was found to be significantly higher in group 1 when compared with the control. Conclusion: In the present study angiotensin converting enzyme, endothelial nitric oxide synthase, and interleukin-6 gene polymorphisms were not associated with coronary artery disease in young or elderly patients. However, in the younger group, Factor V Leiden 'A' allele frequency was significantly higher than that in the control group. Thus, prothrombotic risk factors might be considered an etiological factor for coronary artery disease in younger patients

Surgical treatment of bilateral femoral stress fractures related with long-term alendronate therapy.

A 67-year-old female patient admitted to our outpatient clinic suffering from pain in both thighs for one year without any history of trauma. Patient was receiving alendronate therapy for five years. Physical examination revealed pain increasing with weight-bearing in both thighs with full range of hip and knee movements. Radiographs showed an area of thickened cortex of middle femoral diaphysis in both femurs, but no fracture. Bone scan showed a single area of increased uptake of radioisotope. These images were compatible with stress fractures of both femurs. Dual-energy X-ray absorptiometry revealed a T-score of -3.2 for the lumbar spine and -3.5 for the hip. Alendronate treatment was ceased. Calcium and vitamin D treatment were started. Patient was performed prophylactic surgical stabilization by titanium elastic nails in May 2009. On first day after the surgery, unsupported mobilization and weight-bearing activities were started. Upon persistence of pain on left thigh, plate fixation was performed for the nonunion in June 2012. Patient is now pain-free and able to walk with full weight-bearing without any complications