169 research outputs found

    The Effect of Collimator Diameters on Buildup Factor by using Gamma – Gamma Coincidence System

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    In this work buildup factor of aluminum and copper samples was studied for different thickness using a  gamma _  gamma coincidence technique and by use two collimator 10 and 7 mm, buildup factor  was calculated for thickness ranged between ( 0 - 9.6 ) cm of aluminum and ( 0 - 4.0 ) cm of copper  using  Na - 22  source with activity of   ( 1 micro Curie ) with single energy ( 0.511 MeV ) and by using ( 3 "× 3" ) sodium iodide detector  NaI (TI). The results showed that buildup factor was more accuracy when we used small diameter because this will decrease the scattering ray which make our calculations more acute for buildup factor which is very important in shielding process for gamma ray. Keywords: Buildup factor, Gamma ray, Shield, Coincidence

    Coverage and Capacity Planning of LTE Network for-Taizz City

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    This paper is based on the newly advanced cellular technology called Long Term Evolution (LTE). It is intended to give a good understanding of Radio Network planning of LTE and perform a case study onTaizz City, one of the highest populated cities in Yemen with a selected area of about 118.09km2. The LTE Radio network planning involves coverage estimation, capacity evaluation. In this paper the coverage estimation is done with regards to the real environment dataat its nominal stage to obtain better estimations. Propagation modeling is done using COST HATA W/I model with inclusion of additional parameters obtained from the real environment/terrain what improves the coverage estimation.This in turn, results in a wide coverage, introducing high quality services and excellent mobility support. The simulation is performed using Atoll program to evaluate the traffic demand for all services and to calculate the average throughput of each service

    Solidification enhancement in a multi-tube latent heat storage system for efficient and economical production: Effect of number, position and temperature of the tubes

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    Copyright: © 2021 by the authors. Thermal energy storage is an important component in energy units to decrease the gap between energy supply and demand. Free convection and the locations of the tubes carrying the heat-transfer fluid (HTF) have a significant influence on both the energy discharging potential and the buoyancy effect during the solidification mode. In the present study, the impact of the tube position was examined during the discharging process. Liquid-fraction evolution and energy removal rate with thermo-fluid contour profiles were used to examine the performance of the unit. Heat exchanger tubes are proposed with different numbers and positions in the unit for various cases including uniform and non-uniform tubes distribution. The results show that moving the HTF tubes to medium positions along the vertical direction is relatively better for enhancing the solidification of PCM with multiple HTF tubes. Repositioning of the HTF tubes on the left side of the unit can slightly improve the heat removal rate by about 0.2 in the case of p5-u-1 and decreases by 1.6% in the case of p5-u-2. It was found also that increasing the distance between the tubes in the vertical direction has a detrimental effect on the PCM solidification mode. Replacing the HTF tubes on the left side of the unit negatively reduces the heat removal rate by about 1.2 and 4.4%, respectively. Further, decreasing the HTF temperature from 15◦C to 10 and 5◦C can increase the heat removal rate by around 7 and 16%, respectively. This paper indicates that the specific concern to the HTF tube arrangement should be made to improve the discharging process attending free convection impact in phase change heat storage

    Novel Tellurite Glass (60-x)TeO2–10GeO2 -20ZnO–10BaO - xBi2O3 for Radiation Shielding

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    In this article, high dense glasses based heavy metal former and modifier have been synthesized. The glass system with composition formula of (60-x)TeO2–10GeO2 -20ZnO–10BaO - xBi2O3 (where x = 2.5, 5, 7.5, and 10 mol. %). The glasses have been produced using the usual melt, quenching, and annealing process. Many physical features were investigated. To confirm the amorphous nature of theses glasses, we examined the samples with X-ray diffraction in the range of between 10° and 80°. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) transmission spectrum for the current glass samples within the range of 400–1500 cm−1 has been recorded to study the behavior of the obtained glasses that is mixed between tellurium and germanium glass phase. To study the transparency and cut-off wavelength and other optical properties, Ultraviolet–Visible spectrometer (UV–Vis) was utilized between 200 and 800 nm. Radiation shielding ability of the (60-x) TeO2–10GeO2-20ZnO–10BaO-xBi2O3 glasses was examined. Monte Carlo simulation method was applied to estimate the shielding parameters for gamma photons with various energies varied in rang from 0.015 to 15 MeV. © 2020 Elsevier B.V.All Authors present their grateful acknowledge to the Universiti Putra Malaysia (UPM), for supporting this work by chemicals and services, which granted by UPM under IPB-9554200

    Germanate Oxide Impacts on the Optical and Gamma Radiation Shielding Properties of TeO2-ZnO-Li2O Glass System

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    In this work, a series of tellurite glass combined with various concentrations of germanium oxide was fabricated according to the formula of (70-x)TeO2-xGeO2–20ZnO-10Li2O where x = 5, 10, 15 and 20 mol% via utilizing the melt-quench method for possible use in a radiation shielding applications. X-ray diffraction and Attenuated Total Reflectance Fourier Transform Infrared was employed to investigate the structure of the synthesized glasses. The density and Poisson's ratio for current samples reduced gradually from 5.221–5.008 g.cm−3 and 0.134–0.131, respectively, while the enhancement in bandgap values from 3.700–3.872 eV with addition of GeO2 is observed. The linear attenuation coefficient values at 0.015 MeV are 230.123 and 236.832 cm−1 for samples TG1 and TG4, respectively. Moreover, the lowest half-value layer attained via TG1 and raises from 0.0030 to 3.6684 cm while the highest HVL attained by TG4 and raises from 0.0029 to 3.9696 cm. © 2020 Elsevier B.V.All Authors present their grateful acknowledge to the Universiti Putra Malaysia (UPM), for supporting this work by chemicals and services, which granted by UPM under IPB-9554200. Also, the authors present their grateful acknowledge to the university of Tabuk, Tabuk, Saudi Arabia for supporting this work by some chemicals

    Germanate oxide impacts on the optical and gamma radiation shielding properties of TeO2-ZnO-Li2O glass system

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    In this work, a series of tellurite glass combined with various concentrations of germanium oxide was fabricated according to the formula of (70-x)TeO2-xGeO2–20ZnO-10Li2O where x = 5, 10, 15 and 20 mol% via utilizing the melt-quench method for possible use in a radiation shielding applications. X-ray diffraction and Attenuated Total Reflectance Fourier Transform Infrared was employed to investigate the structure of the synthesized glasses. The density and Poisson's ratio for current samples reduced gradually from 5.221–5.008 g.cm−3 and 0.134–0.131, respectively, while the enhancement in bandgap values from 3.700–3.872 eV with addition of GeO2 is observed. The linear attenuation coefficient values at 0.015 MeV are 230.123 and 236.832 cm−1 for samples TG1 and TG4, respectively. Moreover, the lowest half-value layer attained via TG1 and raises from 0.0030 to 3.6684 cm while the highest HVL attained by TG4 and raises from 0.0029 to 3.9696 cm

    Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

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    BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

    Evaluating The Association Between Serum Hsp27 Antibody and Hypertension in Patients without Underlying Cardiovascular Disease

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    Introduction: An association between heat shock protein 27 (Hsp27) antigen with cardiovascular risk factors has been shown previously. Furthermore, higher levels of serum anti-HSP27 antibodies are also related to higher cardiovascular morbidity and mortality. In the current study, we looked at the relationship between serum Hsp27 antibodies and hypertension, as an important cardiovascular risk factor, in individuals without evidence of cardiovascular disease (CVD).Methods: A sub-population of hypertensive patients (HTN+) without underlying CVD were recruited from the Mashhad stroke and atherosclerosis heart disease (MASHAD) study to assess the association between serum Hsp27 antibodies and hypertension; independent of other cardiovascular risk factors. A total of 1599 people were studied of whom 288 individuals had hypertension and 1311 were used as controls (HTN-).Results: Mean serum Hsp27 antibody titers were 0.20 (0.27) OD in the whole population sample and was not significantly different in the normotensive (HTN-) compared to HTN+ individuals with different degrees of hypertension.Conclusion: There were no significant associations between serum anti-Hsp27 concentrations and either the presence or severity of hypertension. Future studies are warranted to explore the association of anti-Hsp27 antibody and antigen levels and other cardiovascular risk factors
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