23 research outputs found
Disparities in the quality of and access to services in children with autism spectrum disorders: a structural equation modeling
Background: Socioeconomic disparities in health and healthcare are global issues that affect both adults as well as children. Children with exceptional healthcare needs, especially those with developmental impairments, including Autism Spectrum Disorders (ASD), encounter major disparities in access to and quality of health services. However, disparities in the population of children are rarely studied. The main aim of this paper is to study the socioeconomic disparities in children with ASD by examining the association between their Social Determinants of Health (SDH) status and access to and the quality of services. Methods: This is a cross-sectional study on 202 children with ASD conducted in 2019 in two provinces including Ardabil and East-Azerbaijan, in the North-West of Iran. A structured, valid questionnaire was used to collect data on demographic, SDH status, quality of services, and access to services in a population of children with ASD aged 2�16-year-old. Around 77 participants were male and the mean age of children was 2 years and 6 months. Structural Equation Modeling (SEM) were used to assess the relationship. Results: Based on the results of this study, the overall mean scores of the quality of services, access to services, and SDH status were 61.23 (30.01), 65.91 (21.89), and 29.50 (22.32) out of 100, respectively. All the associations between the quality and access dimensions and quality (B: 0.464�0.704) and access (B: 0.265�0.726) scales were statistically significant (P < 0.001). By adjusting to covariates, the access was also significantly related to service quality (P = 0.004). Finally, the associations between SDH score with service quality (P = 0.039) and access (P < 0.001) were positively significant. Conclusions: There are socioeconomic disparities in the quality of and access to services among children with ASD, who use ASD services, in the North-West of Iran. We recommend health/medical centers, where children are diagnosed with ASD, conducting SDH screening and providing families of low-SDH status with specific information about the quality of and access to services for children with ASD. Additionally, medical universities must have a plan to routinely monitor the quality of and access to services provided for the children with low SDH. © 2021, The Author(s)
Preparation of chalcogenide materials for next generation optoelectronic devices
Chalcogenide materials are finding increasing interest as an active material in next generation optical and electronic devices. There wide range of properties, ranging from photosensitivity, ability to host rare earth ions, electrical conductivity, phase change, exceptional optical non-linearities to name only a few are fueling this interest. Moreover, the ability to synthesize these materials in numerous forms as diverse as 2D monolayers, microspheres, optical fibres, nanowires, thin films as well as bulk glass ingots of over a kilogram in size ensures their application space is vast. We began preparation of chalcogenides, largely based on sulphides, in 1992 and since then have built up an extensive capability for their purification, synthesis and fabrication in various forms. A key aspect of this facility is the ability to process in a flowing atmosphere of hydrogen sulphide which provided the capability of synthesis from elemental, oxide or halide precursors, processing through various chemical vapour deposition reactions as well as post purification.In this talk we describe recent additions to the range of materials we synthesize highlighting transition metal di-chalcogenides for electronic applications, an example of which is shown below, crystalline semiconductors for solar cell applications, ion implanted thin films which provide carrier type reversal, low power phase change memory devices, switchable metamaterial devices as well as traditional chalcogenides glass and optical fibre
Modelling, Simulation and Fuzzy Self-Tuning Control of D-STATCOM in a Single Machine Infinite Bus Power System
© 2019 Bentham Science Publishers. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.2174/2352096511666180314141205In recent years, demand for electricity has increased considerably, while the expansion of generation and transmission has been very slow due to limited investment in resources and environmental restrictions. Methods: As a result, the power system becomes vulnerable to disturbances and instability. FACTS (Flexible AC Transmission Systems) technology has now been accepted as a potential solution to this problem. This paper deals with the modelling, simulation and fuzzy self-tuning control of a D-STATCOM to enhance the stability and improve the critical fault clearing time(CCT) in a single machine infinite bus (SMIB).A detailed modelling of the D-STATCOM and comprehensive derivation of the fuzzy logic self-tuning control is presented. Results: The dynamic performance of the power system with the proposed control scheme is validated through in a simulation study carried out under Matlab/Simulink and SimPowerSystems toolbox. Conclusion: The results demonstrate a significant enhancement of the power system stability under the simulated fault conditions considered.Peer reviewe
A comparison of the phenomena of photoluminescence and carrier-type reversal in Bi- and Pb-doped glasses
We present evidence connecting the phenomena of carrier type reversal and photoluminescence (PL), which are observed in certain Bi- and Pb-doped glasses. We also report PL from Bi- and Pb-implanted glass, and that the order of the reaction which generates optically active Bi centers varies significantly between different glass hosts.Comparing contour plots of PL spectra at various excitation wavelengths of Bi-doped chalcogenide, Bi-doped germanate and Pb-doped germanate glasses, indicates that five absorption/PL bands are in approximately the same position. This suggests that very similar active centers are present in Bi- and Pb-doped oxide and chalcogenide glasses. In 4% and 10% PbO doped germanate glass, one and two crystallization temperatures, respectively, can be observed. This could be seen as being analogous to the phase separation observed in Bi-doped GeS glasses displaying carrier-type reversal when the Bi content is increased past 11 mol%. When excited at 782 nm, Bi- and Pb- implanted gallium-lanthanum-sulphide-oxide (GaLaSO) glass thin films display PL bands centered at 820 nm and 860 nm, respectively. The intensity (I) of the 820 nm PL band has a power law dependence on Bi dose (d) of d1.4; a similar power-law dependence occurs in a Bi melt-doped oxide glass. When excited at 514 nm, Bi-implanted GaLaSO thin films display a PL band at 700 nm, which is not present in a Bi melt-doped chalcogenide glass having a similar composition to the implanted glass. This indicates that new Bi centers are formed through implantation, which are absent in the melt-doped glasses. This has important implications for Bi-doped glass lasers, in which the control of Bi centers is critical for improving performance. We report Bi-related red PL bands in Bi-implanted bulk Ge33S67 and Ga5Ge25S70 glasses, and NIR PL bands in Ge23Ga12S64Bi1 glass; all of which have very similar compositions to those in which carrier-type reversal has been observed. This indicates that Bi-related PL and carrier-type reversal may be caused by the same Bi centers.We determined the reaction order for the generation of Bi centers in various oxide glass hosts by extracting absorption data from previously published work, and measuring the gradient (equivalent to the power-law factor) of a double-logarithmic plot of Bi-related absorption coefficient against Bi2O3 doping concentration. The reaction order in Bi-doped oxide glasses decreased with increasing optical basicity of the glass host. A sequential redox reaction involving the decomposition of Bi2O3 into BiO, then Bin clusters, can explain a reaction order dependence on optical basicity. We suggest that red and NIR PL bands result from Bi2+ and Bin clusters, respectively, and these centers are also related to carrier type reversal
Synergetic effect of graphene oxide and C3N4 as co-catalyst for enhanced photocatalytic performance of dyes on Yb2(MoO4)3/YbMoO4 nanocomposite
Here in, we report synthesis of novel hybrid photocatalyst by assembling graphene oxide (GO) and carbon nitride over Yb2(MoO4)3/YbMoO4 nanocomposite in order to investigate degradation of rhodamine B, methylene blue, and methyl orange. In addition, different capping agents (e.g. PEG, PVP, SDS, CTAB and Triton X-100) were utilized to investigate their impact on the morphology and particle size of the Yb2(MoO4)3/YbMoO4 nanocomposite. On the top of that, different parameters such as various mass ratio of precursors (GO, C3N4, Yb2(MoO4)3/YbMoO4), pH value, photocatalyst concentration were altered to investigate their impact on the degradation efficiency. Degradation results reveal that Yb2(MoO4)3/YbMoO4/GO and Yb2(MoO4)3/YbMoO4/C3N4 exhibits higher photocatalytic activity in comparison with pure Yb2(MoO4)3/YbMoO4. The crystalline phases, structure, morphology, and optical properties were characterized by a couple of techniques including X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and energy dispersive X-ray microanalysis. According to the BET results, Yb2(MoO4)3/YbMoO4/GO has specific surface area 1.5 times higher than pure Yb2(MoO4)3/YbMoO4. © 2019 Elsevier Ltd and Techna Group S.r.l
Synergetic effect of graphene oxide and C3N4 as co-catalyst for enhanced photocatalytic performance of dyes on Yb2(MoO4)3/YbMoO4 nanocomposite
Here in, we report synthesis of novel hybrid photocatalyst by assembling graphene oxide (GO) and carbon nitride over Yb2(MoO4)3/YbMoO4 nanocomposite in order to investigate degradation of rhodamine B, methylene blue, and methyl orange. In addition, different capping agents (e.g. PEG, PVP, SDS, CTAB and Triton X-100) were utilized to investigate their impact on the morphology and particle size of the Yb2(MoO4)3/YbMoO4 nanocomposite. On the top of that, different parameters such as various mass ratio of precursors (GO, C3N4, Yb2(MoO4)3/YbMoO4), pH value, photocatalyst concentration were altered to investigate their impact on the degradation efficiency. Degradation results reveal that Yb2(MoO4)3/YbMoO4/GO and Yb2(MoO4)3/YbMoO4/C3N4 exhibits higher photocatalytic activity in comparison with pure Yb2(MoO4)3/YbMoO4. The crystalline phases, structure, morphology, and optical properties were characterized by a couple of techniques including X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and energy dispersive X-ray microanalysis. According to the BET results, Yb2(MoO4)3/YbMoO4/GO has specific surface area 1.5 times higher than pure Yb2(MoO4)3/YbMoO4. © 2019 Elsevier Ltd and Techna Group S.r.l
Non-equilibrium doping of amorphous chalcogenides
The doping of amorphous chalcogenides to control their electronic properties, and specifically change the dominant charge carrier type from holes to electrons, has been a major research challenge for many years. Generally attempts to achieve this through doping during the glass forming phase have been frustrated by autocompensation effects mediated via charged defects resulting in Fermi level pinning. To date progress in this area has remained limited to Bi and Pb-doped GeX (X = S, Se, Te) systems where high doping levels (6-11%) have shown carrier type reversal (CTR) from p-type to n-type.We have readdressed the issue of CTR in amorphous chalcogenides by exploring the concept of non-equilibrium doping, corresponding to the introduction of dopants into the glass matrix following the formation of the network. To achieve this we utilize ion-implantation thereby enabling doping with a wide choice of ion species into any solid chalcogenide system. A number of amorphous chalcogenides systems have been studied including GeX, Ge2Sb2Te5 and GaLaS-based glasses deposited onto substrates via sputtering to form thin films. The structural, electrical and optical properties of the doped systems have been studied in detail revealing their significant modification and aiding understanding of the effect of non-equilibrium doping on these various systems. In particular a series of fabricated chalcogenide/n(p)-type Si devices enable detailed examination of the role of trap states in determining the electrical properties.We demonstrate the success of our non-equilibrium doping approach through achieving CTR in the GeX systems as lower doping concentrations than previously shown possible using conventional approaches. Furthermore, we demonstrate CTR for the first time in a non-GeX system, demonstrating the fabrication of pn-junction devices which are characterized for their electronic and optical behavior
Survey of Multi-sensor Image Fusion
The paper presents multi-sensor image fusion and its relevant framework and technical characteristics. The image fusion is divided into three level fusions: pixel level, feature level and decision level. It mainly discusses the image fusion algorithm at all levels of fusion, and then makes the summary and comparison of these algorithms. Since the high-level algorithms are related to some relevant practical applications of the image fusion, it is in general difficult to be summarized. So this paper also presents some typical algorithms of the feature and decision levels from the perspective of the applications, to provide the necessary summary of the high level image fusion algorithm. Further, the three levels of implementation schemes are described, followed by the comparison and summary for the image evaluation criteria of the fusion method. Some problems and future directions about the multi-sensor image fusion are finally given