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

Compressive Fluorescence Microscopy for Biological and Hyperspectral Imaging

The mathematical theory of compressed sensing (CS) asserts that one can acquire signals from measurements whose rate is much lower than the total bandwidth. Whereas the CS theory is now well developed, challenges concerning hardware implementations of CS-based acquisition devices---especially in optics---have only started being addressed. This paper presents an implementation of compressive sensing in fluorescence microscopy and its applications to biomedical imaging. Our CS microscope combines a dynamic structured wide-field illumination and a fast and sensitive single-point fluorescence detection to enable reconstructions of images of fluorescent beads, cells and tissues with undersampling ratios (between the number of pixels and number of measurements) up to 32. We further demonstrate a hyperspectral mode and record images with 128 spectral channels and undersampling ratios up to 64, illustrating the potential benefits of CS acquisition for higher dimensional signals which typically exhibits extreme redundancy. Altogether, our results emphasize the interest of CS schemes for acquisition at a significantly reduced rate and point out to some remaining challenges for CS fluorescence microscopy.Comment: Submitted to Proceedings of the National Academy of Sciences of the United States of Americ

The Influence of Long-Acting Somatostatin Analogs on 68 Ga-DOTATATE Uptake in Patients With Neuroendocrine Tumors

Purpose A high SUVmax tumor-to-liver ratio (TLR) of 68Ga-DOTATATE can be used to select patients with neuroendocrine tumors (NETs) for peptide receptor radionuclide therapy (PRRT). In addition, an SUVmax TLR ≥ 8.1 is associated with increased progression-free survival in NET patients treated with somatostatin analogs (SSAs). To avoid a theoretical interaction, several guidelines recommend performing PET/CT just before the monthly administration of long-acting SSAs. We aimed to investigate the effect of SSA on the SUVmax of 68Ga-DOTATATE in patients with NET and to identify independent predictors for high SUVmax TLR. Patients and Methods For this retrospective study, 192 68Ga-DOTATATE PET/CT scans of 165 patients without (n = 115) and with (n = 77) SSA (octreotide or lanreotide) in the 3 months before PET/CT were collected and reviewed. The effect of SSA on SUVmax values was analyzed by a maximum likelihood mixed model. Results Patients with SSA had a significantly higher median SUVmax TLR than patients without SSA (4.7 [IQR], 3.1-7.7) versus 3.2 [IQR, 2.0-5.4]; P < 0.001). Multivariable logistic regression analysis showed that SSA use was an independent predictor for SUVmax TLR ≥ 8.1 (odds ratio, 2.91; 95% confidence interval, 1.26-6.72; P = 0.012). Conclusions Our data suggest that higher SSA concentrations do not have a negative effect on 68Ga-DOTATATE uptake in tumor lesions. In addition, we found that only SSA use was associated with SUVmax TLR ≥ 8.1. Our results are consistent with previously conducted studies and in line with the recently published guideline that suggests that the relatively recent use of SSA does not necessitate any delay in 68Ga-DOTATATE PET/CT imaging

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