365 research outputs found
Photoproduction of prompt photons and neutral pions at high transverse momentum
No full textThis thesis describes an experiment carried out at CERN SPS North Area (NA14) to study the photoproduction of prompt photons at high transverse momentum (1 ≤ P_t ≤ GeV/c). Theoretical aspects of the subject are presented and the principle experimental techniques used in the NA14 experiment to produce a high energy (< E> ) im 80 GeV) and high intensity (im106) tagged photon beam are discussed. This is then followed by a description of a lead-scintillator sandwich calorimeter (one of the three in the experiment) with which the Author has been involved with throughout its development and operation. The calorimeter data analysed in this thesis was collected during 1982/83 run periods. Emphasis has been put on the method of analysis since a comprehensive understanding of this is fundamental to a proper appreciation of the subject matter. Large-Pt πo's are also reconstructed and are used in fine tuning of the calorimeter. Final results indicate that the observed πo spectrum is well described by a parametrization describing the VMD component of the photon structure function. This parametrization is also used in a simulation program to evaluate the background to the observed spectrum of single photons. After subtracting the contributions from various sources of background, a clear excess of single photons is observed which is attributed to prompt photons.</p
Treating municipal solid waste leachate in a pilot scale upflow anaerobic sludge blanket reactor under tropical temperature
No full textAims: The objective of this study was to investigate an Upflow Anaerobic Sludge Blanket (UASB) reactor efficiency in treating municipal landfill leachate, under tropical temperature.
Materials and Methods: A 30-liter pilot-scale UASB reactor was used to treat the municipal solid waste leachate, under tropical temperature, for 230 days. The reactor was inoculated with 10 liters of anaerobic sludge from an anaerobic digester, in an agro industry′s wastewater treatment plant. The Volatile Suspended Solids (VSS) of sludge were 65 g/L, with volatile suspended solids to suspended solids (VSS/SS) ratio of 0.74. The reactor was operated in mesophilic (34 - 39°C) temperature.
Results: After reaching a stable operation, the reactor was exposed to raw leachate, with mean chemical oxygen demand (COD) concentrations of 35 g/L. The leachate was diluted to 9 - 10 g/L at Organic Loading Rates (OLRs) of 2, 6, 12, 15 g COD/L.d and decreased again to 12 g COD/L.d, resulting in 45, 76, 84, 68, and 79% removal efficiency and increased again to 87% removal efficiency for COD, at Hydraulic Retention Times (HRTs) of 6, 1.6, 0.83, and 0.67 days, respectively, in the UASB. In the reactor used in this study, the heavy metals were removed by adsorption on biomass, and the maximum removal rate was 68% for Zinc (Zn).
Conclusions: It was concluded that the optimum OLR for diluted leachate up to 10 g COD/l, was 12 g COD/L.d at an HRT of 0.67 day (16 hours)
Telepediatric assistance in Iran: Specialist and subspecialty challenges
No full textINTRODUCTION: Having justice for easy access to health services may probably be a standard feature and indisputable right of all health policies. The health policy of Iran enunciates this right. Unfortunately, as may happen in many countries, the execution of this policy depends on different factors. Among these parameters should be quoted as the suitable distribution of professionals, hospitals, and medical facilities. On the other hand, in Iran, there are many other problems linked to accessing areas with natural hindrances. OBJECTIVE: In this study, we analyzed the primary studies that report specialty and subspecialty challenges that had been faced by Iran to improve pediatric assistance. METHODS: Conduction of literature search in PubMed and CINAHL libraries was done, especially studies from 2010 to 2019. A Boolean operated ‘MeSH’ term was used for search. Newcastle–Ottawa Scale (NOS) scoring was adopted to assess the quality of each study. RESULTS: A total of 118 studies were displayed, and among them, 102 were excluded due to duplication and study relevance. Study selection was made based on its content were classified into two groups (1) shortage and unsuitable distribution of specialist and sub-specialist physicians in Iran, and (2) studies that explain the status of degradation in different areas of Iran. Outcomes demonstrated that Iran is generally suffering the shortage and unsuitable distribution of specialists and sub-specialists. This lack is particularly crucial in deprived and far-away areas from the cities. CONCLUSION: The present study analyzed in detail the current data regarding pediatric health services (specialist and subspecialty) and health-specific facilities distribution in the country
Effect of Humidity on Gas Sensing Performance of Carbon Nanotube Gas Sensors Operated at Room Temperature
No full textCarbon nanotubes (CNTs) have shown promising results for gas sensing due to their high surface area. Since humidity has a great impact on the electrical conductivity of resistive CNT gas sensors, we have investigated the change of humidity on their sensing properties. In this study, we fabricated vertically aligned CNT-based gas sensors for the detection of volatile organic compounds. The morphologies and phase structures of the fabricated samples were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR), confirming the presence of CNT with some surface impurities. It was found that a relative humidity increase from 10% to 80% can reduce the electrical conductivity of the sensor by around 4%. On the other hand, for a humidity above 80% the conductivity increased slightly. The fabricated device has been used as a gas sensor for volatile organic compounds, and the cross-sensitivity to humidity was investigated. It was found that in the fabricated sensors, a change in humidity up to 80% results in a 40% decrease in the response for the studied organic compounds.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
CZTSe-Based Solar Cell Performance Improvement Using the CSLO Technique
No full textHere we investigated a novel layer-based optimization technique to improve the performance of a CZTSe solar cell. By using this technique, the optical behavior and electrical properties of the proposed solar cell improved significantly as a result of the changes in the layer specifications and the layer materials. The structure of the cell consisted of an absorber laid on a conducting layer and covered by Indium Tin Oxide (ITO), with ZnO on its top surface. Due to the employment of the CSLO technique, a p+pn junction was formed between the absorber and window layers, which provided a lower recombination rate by transmitting more electrons and holes to the contacts. In addition, the main important parameters affecting the solar cell’s performance such as layer thickness, carrier lifetime, and total effect density were investigated. According to the results, the proposed CZTSe solar cell achieved a 32.6% and 79.5% efficiency and fill factor, respectively—which in comparison to a conventional solar cell is remarkable. Moreover, hybrid structures made by utilizing CZTS-based, Ge-based Cu2ZnGeSe4, and Si-based Cu2ZnSiSe4 with the proposed CZTSe-based solar cell were implemented and better results were achieved, yielding an efficiency of about 42, 50, and 34% and a fill factor of 66, 55, and 42%, respectively, due to the materials’ properties.Electronic Components, Technology and Material
Ethnolinguistic influence on citation in English and Persian hard and soft science research articles
No full textCitation, as a central and integral issue in academic writing, has been the focus of many recent scholarly articles to highlight the significant role of this discursive practice in the realm of research article writing. Nonetheless, most of the previous studies, with notable exceptions, examined disciplinary influences on citation practices independently of ethnolinguistic influences, and vice versa. The present study investigates the doubly contrastive language-discipline perspective on the one hand and draws a distinction between disciplinary cultures and national cultures on the other. A corpus of 240 research articles sampled from leading Persian and English language medium journals of applied linguistics and psychology as representatives of soft sciences, and computer engineering and mechanical engineering as representatives of hard sciences, was examined drawing on Coffin?s (2009) integrative analytic framework. Quantitative and qualitative analyses of the several aspects of citation features of Bakhtinian dialogism demonstrated some cross-disciplinary and cross-linguistic similarities and differences. Pedagogical implications derived from these findings are discussed
Patterns of mortality among adults with intellectual and developmental disabilities in Ontario
No full textObjectives: To determine recent mortality rates among Ontarian adults with intellectual and developmental disabilities (IDDs) and investigate changes over time in contrast to the general population. To determine the most commonly reported underlying causes of death and explore related coding practices. Methods: Using linked health administrative data, four cohorts of adults with IDD aged 25–99 living in Ontario were followed for 1 year (one cohort for each year between 2011 and 2014). Deaths (2011 to 2014) and causes of death (2011 to 2013) were identified, and age-standardized mortality rates were calculated annually. For 2013, overall and sex-specific standardized mortality ratios (SMRs) were calculated. Mortality ratios were also examined across 5-year age groups. Commonly reported causes of death were tabulated by ICD-10 chapter, differences by sex examined, and cause-specific SMRs calculated. All deaths with IDD diagnostic codes reported as underlying cause of death were identified. Results: Mortality rates among individuals with IDD have been decreasing over time; in 2014, the mortality rate was 22.6 deaths per 1000 person-years. Disparities in mortality rates relative to the general population decreased with increasing age. Men with IDD had higher mortality rates than women with IDD. The most common causes of death among individuals with IDD were cardiovascular disease, neoplasms, and diseases of the respiratory system. An IDD diagnostic code was reported as cause of death in 3.8% of cases. Conclusions: The ongoing excess mortality among Ontarians with IDD should be closely monitored by policy makers and service providers. Attention to cause of death reporting should be considered so that cause of death can be thoroughly examined. This is a post-peer-review, pre-copyedit version of an article published in the Canadian Journal of Public Health. The final authenticated version is available online at https://doi.org/10.17269/s41997-018-0124-
Effect of temperature and humidity on the sensing performance of TiO<sub>2</sub>nanowire-based ethanol vapor sensors
No full textIn this paper, we study the influence of two key factors, temperature, and humidity, on gas sensors based on titanium dioxide nanowires synthesized at 4 different temperatures and with different morphology. The samples' structure are investigated using SEM, XRD and FTIR analysis. The effects of humidity and temperature are studied by measuring the resistance and gas response when exposed to ethanol. At room temperature, we observed a 15% sensitivity response to 100 ppm of ethanol vapor and by increasing the operating temperature up to 180 C, the response is enhanced by two orders of magnitude. The best operating temperature for the highest gas response is found to be around 180 C. Also, it was observed that every nanowire morphology has its own optimum operating temperature. The resistance of sensors is increased at higher Relative Humidity (RH). Besides, the response to ethanol vapor experiences a gradual increase when the RH rises from 10% to 60%. On the other hand, from 60% to 90% RH the gas response decreases gradually due to different mechanisms of interaction of the TiO2 with H2O and ethanol molecules.</p
Investigating Organic Vapor Sensing Properties of Composite Carbon Nanotube-Zinc Oxide Nanowire
No full textThe low operating temperature of nanowire gas sensors along with their high surface-to-volume ratio are two factors that make gas sensors more practical. In this paper, the growth of ZnO nanowires on a vertically aligned CNT forest is reported. The utilized method for ZnO growth was a rapid microwave-assisted hydrothermal route, which facilitates low-temperature and ultra-fast fabrication. Organic vapor sensing properties of fabricated samples were studied in response to different alcoholic vapors at a wide operating temperature range of 25 to 300◦C. Enhancement of the gas response was observed with increasing operating temperature. Moreover, the effect of the ZnO nanowire length on organic vapor sensing properties of CNT-ZnO samples was investigated. Results proved that CNT-ZnO samples with long ZnO wires exhibit higher sensitivity to examined analytes. Different length ZnO nanowires were attained via variation of the microwave exposure time and power. Fabrication parameters were selected based on numerous runs. The length of ZnO synthesized at each distinct run was calculated based on SEM micrographs of the samples.Bio-Electronic
Gas Selectivity Enhancement Using Serpentine Microchannel Shaped with Optimum Dimensions in Microfluidic-Based Gas Sensor
No full textA microfluidic-based gas sensor was chosen as an alternative method to gas chromatography and mass spectroscopy systems because of its small size, high accuracy, low cost, etc. Generally, there are some parameters, such as microchannel geometry, that affect the gas response and selectivity of the microfluidic-based gas sensors. In this study, we simulated and compared 3D numerical models in both simple and serpentine forms using COMSOL Multiphysics 5.6 to investigate the effects of microchannel geometry on the performance of microfluidic-based gas sensors using multiphysics modeling of diffusion, surface adsorption/desorption and surface reactions. These investigations showed the simple channel has about 50% more response but less selectivity than the serpentine channel. In addition, we showed that increasing the length of the channel and decreasing its height improves the selectivity of the microfluidic-based gas sensor. According to the simulated models, a serpentine microchannel with the dimensions W = 3 mm, H = 80 µm and L = 22.5 mm is the optimal geometry with high selectivity and gas response. Further, for fabrication feasibility, a polydimethylsiloxane serpentine microfluidic channel was fabricated by a 3D printing mold and tested according to the simulation resultsElectronic Components, Technology and Material
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