Development of Numerical Method for Optimizing Silicon Solar Cell Efficiency

This paper presents a development of numerical method to determine and optimize the photocurrent densities in silicon solar cell. This method is based on finite difference algorithm to resolve the continuity and Poisson equations of minority charge carriers in p-n junction regions by using Thoma’s algorithm to resolve the tridiagonal matrix. These equations include several physical parameters as the absorption coefficient and the reflection one of the material under the sunlight irradiation of AM1.5 solar spectrum. In this work, we study the effect of various parameters such as thickness and doping concentration of the (emitter, base) layers on crystalline silicon solar cell perfomance. The obtained results show that the optimum energy conversion efficiency is 22.16 % with the following electrical parameters solar cell Voc = 0.62 V and Jph = 43.20 mA · cm – 2. These results are compared with experimental data and show a good agreement of our developped method

A rare cause of chronic mesenteric ischemia from fibromuscular dysplasia: a case report

<p>Abstract</p> <p>Introduction</p> <p>Chronic mesenteric ischemia is a condition that is classically associated with significant atherosclerosis of the abdominal arteries, causing postprandial abdominal pain out of proportion to physical examination. The abdominal pain is exacerbated after meals due to the shunting of blood away from the intestines to the stomach, causing relative ischemia. More than 95% of chronic mesenteric ischemia cases are due to atherosclerosis. We report the first known case of chronic mesenteric ischemia from fibromuscular dysplasia. To the best of our knowledge, this is also the first known case in the literature where postprandial abdominal pain was the presenting symptom of fibromuscular dysplasia.</p> <p>Case presentation</p> <p>A 44-year-old Caucasian woman with a history of hypertension and preeclampsia, who had taken oral contraceptive pills for 15 years, presented with an intractable, colicky abdominal pain of two weeks duration. This abdominal pain worsened with oral intake. It was also associated with diarrhea and vomiting. Physical examination revealed stage III hypertension out of proportion to her risk factors and diffuse abdominal pain without peritoneal signs. An abdominal computed tomography scan, completed in the emergency room, revealed nonspecific colitis. Laboratory work revealed leukocytosis with a left shift, an erythrocyte sedimentation rate of 79 and a C-reactive protein level of 100. She was started on intravenous flagyl and intravenous ciprofloxacin. However, all microbial cultures were negative including three cultures for clostridium difficile. Urine analysis revealed nephritic range proteinuria. The laboratory profile was within normal limits for perinuclear-anti-neutrophil cytoplasmic antibody, cytoplasmic-anti-neutrophil cytoplasmic antibody, anti-saccharomyces cerevisiae antibody, antinuclear antibody test, celiac profile, lactate, carbohydrate antigen-125 and thyroid stimulating hormone. A colonoscopy was completed, which revealed diffuse colonic lymphoid reactive hyperplasia. A small bowel series was negative for any inflammation. An indium scan, pan-computed tomography scan and transvaginal ultrasound were also negative. Magnetic resonance angiography of her abdomen revealed proximal superior mesenteric artery stenosis, which was confirmed by computed tomography angiogram findings of severe proximal and distal superior mesenteric artery stenosis, consistent with the appearance of fibromuscular dysplasia on angiography in the absence of vasculitis or atherosclerotic disease. The patient's superior mesenteric artery stenosis was subsequently angioplastied suboptimally and had to be stented with an Angioplus stent. One month after she was admitted, her abdominal pain and tolerance to oral feeds improved tremendously.</p> <p>Conclusion</p> <p>Fibromuscular dysplasia most commonly presents with renal artery stenosis, which rarely causes abdominal pain. This case illustrates how fibromuscular dysplasia can present as a rare cause of chronic mesenteric ischemia, similar to chronic mesenteric ischemia from atherosclerosis.</p

Effect of high-salt diet on blood pressure and body fluid composition in patients with type 1 diabetes: randomized controlled intervention trial

INTRODUCTION: Patients with type 1 diabetes are susceptible to hypertension, possibly resulting from increased salt sensitivity and accompanied changes in body fluid composition. We examined the effect of a high-salt diet (HSD) in type 1 diabetes on hemodynamics, including blood pressure (BP) and body fluid composition. RESEARCH DESIGN AND METHODS: We studied eight male patients with type 1 diabetes and 12 matched healthy controls with normal BP, body mass index, and renal function. All subjects adhered to a low-salt diet and HSD for eight days in randomized order. On day 8 of each diet, extracellular fluid volume (ECFV) and plasma volume were calculated with the use of iohexol and 125I-albumin distribution. Hemodynamic measurements included BP, cardiac output (CO), and systemic vascular resistance. RESULTS: After HSD, patients with type 1 diabetes showed a BP increase (mean arterial pressure: 85 (5) mm Hg vs 80 (3) mm Hg; p<0.05), while BP in controls did not rise (78 (5) mm Hg vs 78 (5) mm Hg). Plasma volume increased after HSD in patients with type 1 diabetes (p<0.05) and not in controls (p=0.23). There was no significant difference in ECFV between diets, while HSD significantly increased CO, heart rate (HR) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in type 1 diabetes but not in controls. There were no significant differences in systemic vascular resistance, although there was a trend towards an HSD-induced decrease in controls (p=0.09). CONCLUSIONS: In the present study, patients with type 1 diabetes show a salt-sensitive BP rise to HSD, which is accompanied by significant increases in plasma volume, CO, HR, and NT-proBNP. Underlying mechanisms for these responses need further research in order to unravel the increased susceptibility to hypertension and cardiovascular disease in diabetes. TRIAL REGISTRATION NUMBERS: NTR4095 and NTR4788

Towards understanding and eliminating defects in additively manufactured CubeSat mirrors

Fabricating mirrors using additive manufacturing (AM; 3D printing) is a promising yet under-researched production route. There are several issues that need to be better understood before AM can be fully adopted to fabricate mirror substrates. A significant obstacle to AM adoption is the presence of porosity and the influence that has on the resultant optical proprieties. Several batches of high-silicon aluminium (AlSi10Mg) samples were created to investigate the relationships laser parameters, laser paths and build orientations have with the porosity. The results showed that eliminating defects relies on a complex interaction of the process parameters and material properties, with the residual heating from the laser proving to be a significant factor. In addition, the use of a hot isostatic press is investigated and some full prototypes of the Cassegrain CubeSat were produced

QuPWM: Feature Extraction Method for MEG Epileptic Spike Detection

The used data set are already quantized frames extracted using frame length = 100 sample and step=2 sample from three MEG session of two healthy patient (E001 and E002) and three MEG session of two epileptic patient (C001 and C002). These signal are licensed to National Neural Institute- King Fahad Medical City (NNI-KFMC), Riyadh, Saudi Arabia. This data was conducted in accordance with the approval of the Institutional Review Board at KFMC (IRB log number: 15-086, 2015). For more information, Please contact professor Saleh Alshebeili at : [email protected]

Impedance spectroscopy as a tool to monitor the adsorption and removal of nitrate ions from aqueous solution using zinc aluminum chloride anionic clay

In this study, Zn3AlCl ionic clay was used to investigate the adsorption mechanism of the nitrate ions in solutions containing nitrate ions at different contact time. The clay was synthesized by coprecipitation method at room temperature, and this sample was characterized by XRD, Fourier transform-infrared (FT-IR) and inductively coupled plasma (ICP). This sample was crystallized in a rhombohedral symmetry (Space group: R-3 m). Impedance spectroscopy was used as a tool to evaluate and monitor the adsorption process at different contact time 5; 10; 20; 30; 60 min and the clay alone. The impedance measurement was well analyzed and fitted with an equivalent circuit containing both (R//CPE) connected in series. Furthermore, the σac conductivity was also investigated as a function of frequency. It was analyzed and fitted using double power law: σac(ω)=σdc+Aωs1+Bωs2,(0≤s1≤1and0≤s2≤1). This study reveals the existence of two relaxation processes with different relaxation times, which could be attributed to the grain and grain boundaries, and exhibit high values of dielectric constant at low frequencies