The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells

Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.Comment: 8 pages, 12 figures, Data presented at 2006 NSREC, Final Version to be published in IEEE Transactions on Nuclear Science, 53, NO. 6, December 2006. Index Terms: GaAs, Ion-irradiation, Lithium, NIEL, Photovoltaic cells, Radiation effects, Silico

Microfluidic synthesis of colloidal nanomaterials

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006.Includes bibliographical references.This thesis focuses on microfluidics based approaches for synthesis and surface-engineering of colloidal particles. Bottom-up assembly through colloidal nucleation and growth is a popular route to the controlled synthesis of nanomaterials. Standard bench-scale synthetic chemistry techniques often involve non-uniform spatial and temporal distributions of concentration and temperature, and are not readily scalable. Photolithography-based microfabrication enables the application of classical techniques of chemical reaction engineering to design chemical reactors that cannot be realized easily at the macroscale, and that closely approach theoretical 'idealized' reactor configurations. In addition, the microfluidic format allows precisely controlled reaction conditions such as rapid mixing, and concentration and temperature uniformity. The goal of this thesis was to design microfluidic reactors for synthesis of core-shell colloidal particles with tunable sizes. Microscale segmented gas-liquid flows overcome the large axial dispersion effects associated with single-phase laminar flows. Microchannel devices that yielded uniform, stable gas-liquid segmented flows over three orders of magnitude in flow velocity were first developed.(cont.) Extensive experimental studies of the transport, dynamics and stability of such flows were then conducted with pulsed-laser fluorescent microscopy, optical stereomicroscopy and micro particle image velocimetry (-PIV). Flow segmentation not only reduces axial dispersion, but also allows rapid micromixing of miscible liquids through internal recirculations in the liquid phase. This added functionality is especially useful in syntheses involving colloidal particles that, due to inherently low diffusivity, cannot be rapidly mixed by laminar diffusive techniques. Continuous segmented flow reactors were then developed for the synthesis of colloidal silica and titania particles by sol-gel chemistry. Particle sizes could be tuned by varying the rates of flow of reactants, or by varying the chip temperature. Particle size distributions comparable to or narrower than the corresponding stirred-flask synthesis, with little agglomeration or shape distortion were obtained. Coating of colloidal particles with one or more layers of different materials is used to modify their optical, chemical or surface properties. Core-shell particles are often prepared by controlled precipitation of inorganic precursors onto core particles.(cont.) Synthesis of such structures requires precise control over process parameters to prevent precipitation of secondary particles of shell material and agglomeration of primary particles. Particles coated with titania are exceptionally difficult to synthesize due to the high reactivity of the titania precursors, which makes controlled precipitation difficult. A novel continuous flow microfluidic reactor with sequential multi-point precursor addition was developed for colloidal overcoating processes. Silica particles were coated with uniform titania layers of tunable thickness by the controlled hydrolysis of titanium ethoxide, with no secondary particle formation or agglomeration. An integrated reactor for continuous silica synthesis and in-situ series overcoating with titania was then developed using a two-level stacked reactor fabrication process. Finally, multi-step nanomaterials synthesis and surface coating with incompatible chemistries requires the development of microfluidic 'unit operations' equivalent to particle filtration. In this context, rapid, continuous microfluidic particle separation was demonstrated using transverse free-flow electrophoresis.by Saif A. Khan.Ph.D

Improving the Quality of Healthcare Using Big Data

In India there is a lack of doctorrsquos availability in rural areas compare to urban areas because of which the number of deaths is increasing in the rural areas. To solve this issue we are building an android application (Healtho) which will recommend the disease based on the symptoms given by the end user. Basically, a recommended system will be used by using Hadoop with mahout that is a Big Data concept. By using android as a platform we can provide higher availability of the system to the end user and provide some emergency services like location of nearby Hospitals and blood bank. The system also provides the medicine time (Meditime) in which the end user may come to know at what time the medicine is to be taken. This system could mostly be used by the people who live in rural area because there is lack of doctorrsquos availability and hospitals.nbs

A strong construction of S-box using Mandelbrot set an image encryption scheme

The substitution box (S-box) plays a vital role in creating confusion during the encryption process of digital data. The quality of encryption schemes depends upon the S-box. There have been several attempts to enhance the quality of the S-box by using fractal chaotic mechanisms. However, there is still weakness in the robustness against cryptanalysis of fractal-based S-boxes. Due to their chaotic behavior, fractals are frequently employed to achieve randomness by confusion and diffusion process. A complex number-based S-box and a chaotic map diffusion are proposed to achieve high nonlinearity and low correlation. This study proposed a Mandelbrot set S-box construction based on the complex number and Chen chaotic map for resisting cryptanalytic attacks by creating diffusion in our proposed algorithm. The cryptosystem was built on the idea of substitution permutation networks (SPN). The complex nature of the proposed S-box makes it more random than other chaotic maps. The robustness of the proposed system was analyzed by different analysis properties of the S-box, such as nonlinearity, strict avalanche criterion, Bit independent criterion, and differential and linear probability. Moreover, to check the strength of the proposed S-box against differential and brute force attacks, we performed image encryption with the proposed S-box. The security analysis was performed, including statistical attack analysis and NIST analysis. The analysis results show that the proposed system achieves high-security standards than existing schemes

On the Maximal Rate of Non-Square STBCs from Complex Orthogonal Designs

A linear processing complex orthogonal design (LPCOD) is a ptimesn matrix epsiv, (pgesn) in k complex indeterminates x₁,x₂,...,x_k such that (i) the entries of epsiv are complex linear combinations of 0, plusmnx_i, i = 1,...,k and their conjugates, (ii) epsiv^Hepsiv = D, where epsiv^H is the Hermitian (conjugate transpose) of epsiv and D is a diagonal matrix with the (i,i)-th diagonal element of the form l₁⁽ⁱ⁾|x₁|² + l₂⁽ⁱ⁾|x₂|² +...+ l_k⁽ⁱ⁾|x_k|² where l_j⁽ⁱ⁾,i = 1,2,...,n, j = 1,2,...,k are strictly positive real numbers and the condition l₁⁽ⁱ⁾ = l₂⁽ⁱ⁾ =...= l_k⁽ⁱ⁾, called the equal- weights condition, holds for all values of i. For square designs it is known that whenever a LPCOD exists without the equal-weights condition satisfied then there exists another LPCOD with identical parameters with l₁⁽ⁱ⁾ = l₂⁽ⁱ⁾ =...=l_k⁽ⁱ⁾ = 1. This implies that the maximum possible rate for square LPCODs without the equal-weights condition is the same as that of square LPCODs with equal-weights condition. In this paper, this result is extended to a subclass of non-square LPCODs. It is shown that, a set of sufficient conditions is identified such that whenever a non- square (p>n) LPCOD satisfies these sufficient conditions and do not satisfy the equal-weights condition, then there exists another LPCOD with the same parameters n, k and p in the same complex indeterminates with l₁⁽ⁱ⁾=l₂⁽ⁱ⁾ =...= l_k ⁽ⁱ⁾ = 1

Successful Salvage Treatment of Resistant Acute Antibody-Mediated Kidney Transplant Rejection with Eculizumab

Antibody-mediated rejection (ABMR) jeopardises short- and long-term transplant survival and remains a challenge in the field of organ transplantation. We report the first use of the anticomplement agent eculizumab in Oman in the treatment of a 61-year-old female patient with ABMR following a living unrelated kidney transplant. The patient was admitted to the Sultan Qaboos University Hospital in Muscat, Oman, in 2013 on the eighth day post-transplantation with serum creatinine (Cr) levels of 400 μmol/L which continued to rise, necessitating haemodialysis. A biopsy indicated ABMR with acute cellular rejection. No improvement was observed following standard ABMR treatment and she continued to require dialysis. Five doses of eculizumab were administered over six weeks with a subsequent dramatic improvement in renal function. The patient became dialysis-free with serum Cr levels of 119 μmol/L within four months. This case report indicates that eculizumab is a promising agent in the treatment of ABMR

Improvement in the Mechanical Properties of High Temperature Shape Memory Alloy (Ti 50

High temperature shape memory alloys Ti50Ni25Pd25 and Ti50Ni20Pd25Cu5 were developed, characterized, and tensile tested in both martensite ( Mf − 50°C) and austenite ( Af + 50°C) phases. The transformation temperatures of ternary Ti50Ni25Pd25 alloy were increased by 11 to 12.5°C by substitution of Ni with 5 at% Cu. At the same time, transformation heat absorbed and released during forward and reverse martensitic transformation was also increased. In the martensite phase, the mechanical properties, that is, the stress for reorientation of martensite variants and fracture stress, were increased by 33 and 60 MPa, respectively, whereas the fracture strain was decreased by 1.5%. In the austenite phase, the critical stress for slip and fracture stress were increased by 62 and 40.9 MPa, respectively, whereas the fracture strain was decreased by 1.2%. The increase in both stresses was attributed to the solid solution strengthening by substitution of Ni atoms with relatively greater atomic radius of copper (Cu) atoms. The overall results suggest that the addition of 5 at% Cu in place of Ni in Ti50Ni25Pd25 alloy is very beneficial to improving the mechanical and shape memory properties and increasing the transformation temperatures

Safety and Complications of Double-Lumen Tunnelled Cuffed Central Venous Dialysis Catheters : Clinical and radiological perspective from a tertiary centre in Oman

Objectives: This study aimed to assess the technical success, safety and immediate and delayed complications of double-lumen tunnelled cuffed central venous catheters (TVCs) at the Sultan Qaboos University Hospital (SQUH), Muscat, Oman. Methods: This retrospective study took place between January 2012 and October 2013. The clinical records and radiological data of all patients who underwent ultrasound- and fluoroscopy-guided TVC placement at SQUH during the study period were reviewed. Demographic data and information regarding catheter placement, technical success and peri- and post-procedure complications (such as catheter-related infections or thrombosis) were collected. Results: A total of 204 TVCs were placed in 161 patients. Of these, 68 were female (42.2%) and 93 were male (57.8%). The mean age of the patients was 54.4 ± 17.3 years. The most common reason for catheter placement was the initiation of dialysis (63.4%). A total of 203 procedures were technically successful (99.5%). The right internal jugular vein was the most common site of catheter placement (74.9%). Mild haemorrhage which resolved spontaneously occurred in 11 cases (5.4%). No other complications were observed. Subsequent follow-up data was available for 132 catheters (65.0%); of these, thrombosis-related catheter malfunction was observed in 22 cases (16.7%) and catheter-related infection in 29 cases (22.0%). Conclusion: Radiological-guided placement of tunnelled haemodialysis catheters can be performed safely with excellent technical success. The success rate of catheter insertion at SQUH was favourable in comparison with other studies reported in the literature

Association of MBL2 gene polymorphisms with pulmonary tuberculosis susceptibility: Trial sequence meta-analysis as evidence

© 2019 Mandal et al. Background: Mannose-binding lectin (MBL) or mannose-binding protein (MBP), encoded by MBL2 gene and secreted by the liver, activates complement system through lectin pathway in innate immunity against the host’s infection. Conflictingly, a number of MBL2 variants, rs1800450 (A\u3eB), rs1800451 (A\u3eC), rs5030737 (A\u3eD), rs7096206 (Y\u3eX), rs11003125 (H\u3eL), and rs7095891 (P\u3eQ) allele, have been found to be associated with compromised serum levels and pulmonary tuberculosis (PTB) susceptibility. The present meta-analysis study was performed to evaluate the potential association of these MBL2 gene variants with PTB susceptibility. Materials and methods: A quantitative synthesis was performed on PubMed (Medline), EMBASE, and Google Scholar web database searches. A meta-analysis was performed to calculate the pooled odds ratios and 95% CIs for all the genetic models. Results: A total of 14 eligible studies were included to analyze their pooled data for associations between alleles, genotypes, and minor allele carriers. The statistical analysis revealed the significant reduced PTB risk with homozygous variant genotype of rs1800451 polymorphism (CC vs AA: P=0.043; OR =0.828, 95% CI =0.689–0.994). Contrary to this, the variant allele of rs5030737 polymorphism showed association with increased PTB risk (D vs A: P=0.026; OR =1.563, 95% CI =1.054–2.317). However, the other genetic models of rs1800450 (A\u3eB), rs7096206 (Y\u3eX), and rs11003125 (H\u3eL) MBL2 gene polymorphisms did not divulge any association with PTB susceptibility. Conclusion: The current meta-analysis concludes that rs1800451 (A\u3eC) and rs5030737 (A\u3eD) polymorphisms of MBL2 gene play a significant role in PTB susceptibility. Further, well-designed epidemiological studies with larger sample size including consideration of environmental factors are warranted for the future