Numerical Studies on Supersonic Mixing and Combustion Phenomena

A numerical study is conducted to investigate the mixing, combustion, and flow characteristics of different scramjet-combustor configurations. Three-dimensional models for the combustors have been used. Numerical results are obtained using a finite volume computational fluid dynamics (CFD) code with unstructured grids with sizes between 200,000 and 400,000 cells. In the first part of the current study, the effects of the side angle of the fuel injectors in both mixing and combustion processes are investigated. Raised (compression) and relieved (expansion) wall-mounted ramps are used with side angles of 0 (unswept), 5, and 10 degrees. Results are obtained for nonreacting flows as well as for reacting flows. Hydrogen is used as the fuel in all reacting cases. It is noted that the side angle highly affects the mixing process. The results show clearly that increasing the side angle of the ramps leads to better mixing and further increase of the angle will slightly improve the mixing rate. In the second part, two dual-mode scramjet-combustor models are investigated. In the first model, fuel is injected through a single unswept wall-mounted ramp parallel to the airstream. In the second model, fuel is injected behind a rearward facing step normal to the airstream. The effects of the combustor length, the equivalence ratio, the number, and the arrangements of the fuel injectors are investigated. Also, the effect of the initial boundary layer thickness is studied. Results show that improved combustion efficiency is obtained by increasing the length of the combustor. For the same amount of injected fuel, increasing the number of injectors improves the combustion efficiency. Asymmetric flow and significant upstream interaction are seen in the isolator section of the second model when using initial boundary layer at the inlets. Furthermore, high degree of upstream interaction is obtained by increasing the number of injectors

Investigation of the nanocrytalline SnO2 Synthesized by Homogeneous Precipitation

Nanocrystalline tin dioxide synthesized by the homogeneous pre cipitation method using the reaction of tin tetrachloride pentahydrate and urea solutions has been investigated. The nanocrystalline powder has been traced at different calcination temperatures (300ºC-1050ºC), and then characterized by using   Thermogravemetric analysis, differential thermal analysis and x-ray diffraction. The microstructure of the obtained nanoparticles has been examined by scanning and transmission electron microscopy. The average crystallite size, determined by x-ray diffraction, was found to be in the range of 3 –30 nm. The analysis exhibited a tetragonal phase.  Optical properties were investigated by a UV–vis absorption spectrophotometer. The calculated optical band gap lies between 4.47–3.71 eV as a result of increasing the calcination temperatures and crystallite size. Surface area and porosity of SnO2 nanoparticles are measured. Specific surface area which is related to pore volume and decreases from 155 m2/g at 100ºC to 3.3 m2/g at 1050ºC.Â

Statistical analysis for the impact of smoking on the behavior and health of Qatari adolescents

The links between the use of tobacco and health risks are well known. Most of the younger smokers reside in Asia which includes Qatar, the focus country of this study. Cigarette smoking among children is rising at an alarming rate worldwide including Qatar. As youth make up a significant percentage of the population and to achieve the health objectives of the Qatar Vision 2030, it is essential to ensure the health and well-being of adolescents, as they are the future of Qatar. This study focuses on exploring the patterns of tobacco use and its impacts on the adolescents by conducting a survey in different schools across Qatar. The questionnaire was administered in five schools, selected by proportional random sampling. The responses were recorded from the sample for general questions regarding interest in physical activities, relationship with family and friends, mental satisfaction, health, academics and access to cigarettes. 2018 Walter de Gruyter GmbH, Berlin/Boston 2018.Scopu

Optimirana i validirana protočna injekcijska spektrofotometrijska analiza topiramata, piracetama i levetiracetama u farmaceutskim pripravcima

Application of a sensitive and rapid flow injection analysis (FIA) method for determination of topiramate, piracetam, and levetiracetam in pharmaceutical formulations has been investigated. The method is based on the reaction with ortho-phtalaldehyde and 2-mercaptoethanol in a basic buffer and measurement of absorbance at 295 nm under flow conditions. Variables affecting the determination such as sample injection volume, pH, ionic strength, reagent concentrations, flow rate of reagent and other FIA parameters were optimized to produce the most sensitive and reproducible results using a quarter-fraction factorial design, for five factors at two levels. Also, the method has been optimized and fully validated in terms of linearity and range, limit of detection and quantitation, precision, selectivity and accuracy. The method was successfully applied to the analysis of pharmaceutical preparations.Opisana je osjetljiva i brza protočna injekcijska analiza (FIA) za određivanje topiramata, piracetama i levetiracetama u farmaceutskim pripravcima. Metoda se temelji na reakciji ortho-ftalaldehida i 2-merkaptoetanola u bazičnom puferu i mjerenju apsorbancije na 295 nm u protočnim uvjetima. U svrhu povećanja osjetljivosti i dobivanja reproducibilnih rezultata optimirane su varijable koje utječu na određivanje kao što su volumen injektiranog uzorka, pH, ionska jakost, koncentracija reagensa, brzina protoka reagensa i drugi FIA parametri koristeći četvrt-frakcijski faktorijalni dizajn, za pet faktora na dva nivoa. Metoda je optimirana i potpuno validirana (linearnost, područje određivanja, granica detekcije i kvantifikacije, preciznost, selektivnost i točnost). Metoda je uspješno primijenjena za analizu farmaceutskih pripravaka

Linking Urban Regeneration to Sustainable Urban Development of Smart Cities

Urban regeneration involves the revitalisation of distressed urban areas, through actions such as rehabilitation of historic areas, improvement of living conditions in residential districts, redevelopment of public spaces, and modernisation of urban infrastructure (Alpopi & Manole, 2013). The label 'smart city' has an impact on urban strategies in both large and small towns. It helps to face the increasing problems of urban areas, local public government, companies, non-profit organisations, and the citizens themselves. They all embraced the idea of a smarter city, using more technologies, creating better life conditions and safeguarding the environment for a better quality of life (Dameri & Rosenthal-Sabroux, 2014). This research focuses on adopting an inductive methodology of sustainable urban development in smart cities through a specific framework to be applied on the urban regeneration of city centres in cities with historical background. This will be carried out through the analysis of the interrelationship between the key principles of both urban regeneration and smart cities with the aim to compile a comprehensive list ofprinciples. This inductive methodology will be validated through a comparative study of selected relevant examples. After that the development framework will be used to apply the compiled ideas and principles, and to verify its potential to formulate multiple scenarios of urban regeneration of city centres. After that, the scenarios of development will be tested on a case study of the city of Alexandria in Egypt, by using multiple research methods such as focused interviews, structured questionnaires, personal observation and assessment. This study aims to conclude with a set of guidelines for intervention in similar urbancontexts in general, as well as in the specific case of Alexandria with its particular conditions

Assessment of plasma and urinary transforming growth factor beta 1 (TGF-β1) in children with lupus nephritis

Background: Kidney disease is one of the most serious manifestations of systemic lupus erythematosus (SLE). Despite the improvement in the medical care of SLE in the past two decades, the prognosis of lupus nephritis remains unsatisfactory. Transforming growth factor- β1 (TGF-β1) is an immunosuppressive cytokine, as it inhibits T and B cell proliferation and NK cell cytotoxic activity . Objective: The aim of this study was to assess serum and urinary TGF- β1 levels in children with SLE and their possible role in the renal involvement and activity of the disease. Study design: This cross sectional study was conducted in Nephrology Unit of Pediatric Department, plus Outpatient Clinic of Rheumatology Department, Zagazig University Hospital during the year of 2010. Methods: Twenty-five pediatric patients with SLE were randomly selected and classified according to into 2 groups: Group (Ι): included 13 patients presented with urinary abnormalities and/or disturbed renal function(active nephritis): 5 males, 8 females. Their mean age was 9.7±2.53 years and the mean disease duration was 2.46±1.4 years. Group (ΙΙ): included 12 patients presented by lupus without nephritis : 5 males,7 females. Their mean age was 9.9±2.1 years and the mean disease duration was 2.41±0.9 years. Control group(group ΙΙΙ): Twenty healthy children of matched age and sex served as a control group included 8 males ,12 females. Their mean age was 10.0±2.3 years. Results: There was no significant difference among studied patients groups regarding age, sex , disease duration and lupus therapy (p>0.05). There was a significant difference between both groups regarding urinary albumin and serum creatinine (2.76±0.97 and 1.96±0.84 mg/dl respectively), while there was a high significant difference between them regarding C3 (47.3±12.5 and 76.6±6.6 mg/ml respectively) and anti double stranded DNA (anti-dsDNA) (80.7±32.8 and 26.8±4.5 IU/ml respectively). Plasma TGF- β1 showed significantly lower levels in patients with active nephritis relative to other groups, while urinary TGF- β1 levels were significantly high in SLE patients either with active or silent nephritis when compared with the control group. Plasma TGF- β1 showed a highly significant positive correlation with C3 and a highly significant negative correlation with serum creatinine, urinary albumin, anti dsDNA and SLE disease activity index (SLEDAI) score. While, urinary TGF- β1 had a significant negative correlation with C3 and a high significant positive correlation with anti-dsDNA and SLEDAI score. Conclusion: Low plasma TGF β1 level and increased urinary TGF β1 excretion denotes active renal affection in children with SLE.Keywords: SLE , nephritis , TGF- β1Egypt J Pediatr Allergy Immunol 2011;9(1):21-2

Cellular replacement therapy for liver disease

Liver disease is a major health problem worldwide. The liver performs a wide range of functions, which the human body cannot survive without. The human liver is continuously challenged with infectious organisms, alcohol and chemicals, congenital defects, autoimmunity and malignancy etc. The liver has been imparted a marvelous capacity to regenerate and recover from various insults. However, in many cases liver injuries exceed its regenerative capacity with end-stage liver disease becoming the inevitable end. So far, liver transplantation is still the only treatment modality for end-stage liver disease. However, there are many limitations to liver transplantation towards its applicability and availability for all patients worldwide, such as scarcity of donors as well as other ethical, technical and surgical considerations. Cell transplantation is a frequently studied alternative to organ transplantation in liver disease. Many cell types are under extensive evaluation, with primary human hepatocytes and different stem cell types coming first on the list. For primary human hepatocytes, liver tissue is still needed, and when available, cells are produced in huge numbers requiring cryopreservation. Available hepatocyte cryopreservation protocols still need further optimization. In addition, better cold storage techniques for hepatocytes are needed for the feasibility of frequent cell infusions per patient. Stem cells still need to be studied further for their differentiation potential towards hepatic lineages, safety, immunomodulatory roles, and their possible support for cotransplanted hepatocytes. In this thesis, we addressed a few of the current obstacles facing cellular replacement therapy for liver disease. In the first study, we isolated and characterized a mesenchymal stem cell population from human fetal liver. The hepatic origin, the mesenchymal nature, and the immunomodulatory effects of these cells suggest them as potential candidates for cellular therapy for liver disease. In addition, we transplanted these cells into a mouse model of liver disease with an evidence for their potential differentiation to hepatocyte-like cells in vivo. In the second study, we characterized microRNAs expressed in the human liver. Such information can help understanding the role of microRNAs in liver development and their potential use in microRNA-based stem cell differentiation towards hepatic lineages. In the third study, we introduced a new defined xeno-free cryoprotectant to the field of hepatocyte cryopreservation. This cryoprotectant could be of value when preserving hepatocytes and stem cell-derived hepatocytes in a clinical setting. In the fourth study, we showed that human liver material could be better cold-stored as a whole tissue rather than as single cells. This makes it possible for frequent hepatocyte infusions commonly needed in a clinical context