Nanocomposite solar cells - Influence of particle concentration, size and shape on the device performance

Solar cells based on poly(3-hexylthiophene) (P3HT) :TiO2 nanocomposite films were investigated. We studied the influence of the nanoparticle concentrations and different nanostructures (spherical particles with size ∼5 nm and ∼20-40 nm, and rods with diameter ∼10 nm and length ∼40 nm) on the performance of the nanocomposite solar cells. PL quenching and improved external quantum efficiency (EQE) was observed for all the nanocomposite devices compared to that of pristine P3HT solar cells. However, TiO2 (∼5 nm spheres) and TiO2 rods showed only small improvement in EQE. The small improvement for the 5 nm TiO 2 spheres was attributed to the lack of connectivity of nanoparticles for electron conduction. Therefore, the charge collection efficiency was limited. For TiO2 rods, the tendency of the rods to lie in the plane of substrates also limited the charge conduction and collection in the direction perpendicular to the substrates. Therefore, the improvement of the devices made by these nanoparticles was limited. For TiO2 (20-40 nm spheres) with optimal concentration, external quantum efficiency up to 15% and AM1 power conversion efficiency of 0.42% were obtained. The improvement in the efficiency was related to the improved morphology of the film and was attributed to the formation of percolation paths of TiO2 for electron conduction.published_or_final_versio

Indium-tin-oxide surface treatments: Influence on the performance of CuPc/C60 solar cells

The performance of organic solar cells was influenced by different indium tin oxide (ITO) surface treatments. The uses of Hall measurements, Seebeck coefficient measurements, surface sheet measurements, and surface probe microscopy to characterize ITO sustrates were discussed. The parameters of ITO such as work function, carrier concentration, sheet resistance and surface roughness were changed due to the surface treatments.published_or_final_versio

Influence of the device architecture to the ITO surface treatment effects on organic solar cell performance

In this work, we investigate the influence of different indium tin oxide (ITO) surface treatments on the performance of organic solar cells with different device architectures. Two layer cells with different layer hierarchy (ITO/copper phthalocyanine (CuPc)/fullereve (C60/Al and ITO/C 60/CuPc/Cu) and three layer cells with mixed layer inserted between CuPc and C60 were fabricated. We found that in all cases the short circuit current was the parameter which was most significantly affected by ITO surface treatment. However, the performance of the cells with C60 layer in contact with ITO was markedly less sensitive to the ITO surface treatments compared to the cells with CuPc in contact with ITO. The cells with C60 layer in contact with ITO also exhibited higher efficiency compared to the cells with CuPc in contact with ITO. We also fabricated two layer cells with structures ITO/CuPc/perylene tetracarboxylic acid diimide (PTCDI)/Al and ITO/PTCDI/CuPc/Cu. In this case, we also obtain higher efficiency and lower sensitivity to ITO properties when "n type" material is in contact with ITO. The best obtained AMI power conversion efficiency was 0.4% for ITO/PTCDI/CuPc/Cu cell and ITO/C60/CuPc:C60/CuPc/Cu cells.published_or_final_versio

The Prevalence and Risk Factors of Paternal Depression from the Antenatal to the Postpartum period and the Relationships between Antenatal and Postpartum Depression among Fathers in Hong Kong

Introduction. Despite the fact that maternal perinatal mental health problems have been extensively studied and addressed to be a significant health problem, the literature on paternal perinatal mental health problems is relatively scarce. The present study aims at determining the prevalence of paternal perinatal depression and identifying the risk factors and the relationship between antenatal and postpartum depression. Methodology. 622 expectant fathers were recruited from regional maternal clinics. The expectant fathers were assessed using standardized and validated psychological instruments on 3 time points including early pregnancy, late pregnancy, and six weeks postpartum. Results. Results showed that a significant proportion of expectant fathers manifested depressive symptoms during the perinatal period. Paternal antenatal depression could significantly predict higher level of paternal postpartum depression. Psychosocial risk factors were consistently associated with paternal depression in different time points. Conclusions. The present study points to the need for greater research and clinical attention to paternal depression given that it is a highly prevalent problem and could be detrimental to their spouse and children development. The present findings contribute to theoretical basis of the prevalence and risk factors of paternal perinatal depression and have implications of the design of effective identification, prevention, and interventions of these clinical problems.published_or_final_versio

Medication safety research by observational study design

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Databases in the Asia-Pacific Region: The Potential for a Distributed Network Approach

Background: This study describes the availability and characteristics of databases in Asian-Pacific countries and assesses the feasibility of a distributed network approach in the region. Methods: A web-based survey was conducted among investigators using healthcare databases in the Asia-Pacific countries. Potential survey participants were identified through the Asian Pharmacoepidemiology Network. Results: Investigators from a total of 11 databases participated in the survey. Database sources included four nationwide claims databases from Japan, South Korea, and Taiwan; two nationwide electronic health records from Hong Kong and Singapore; a regional electronic health record from western China; two electronic health records from Thailand; and cancer and stroke registries from Taiwan. Conclusions: We identified 11 databases with capabilities for distributed network approaches. Many country-specific coding systems and terminologies have been already converted to international coding systems. The harmonization of health expenditure data is a major obstacle for future investigations attempting to evaluate issues related to medical costs.postprin

Prevalence and genotypes of α- and β-thalassemia carriers in Hong Kong - Implications for population screening

Background: The thalassemias are common in southern China. We determined the prevalence of heterozygous carriers of these genetic disorders in Hong Kong and assessed the feasibility of a community-based screening program. Methods: An educational and screening program for the thalassemias was carried out in three high schools with a total of 2420 students. Seventy- five percent of the students agreed to undergo screening, which consisted of blood counts, hemoglobin electrophoresis, serum ferritin measurements, and DNA analyses. Results: Of the 1800 blood samples tested, 150 (8.3 percent) had microcytosis (mean corpuscular volume, <80 μm3). Ninety students (5.0 percent) were carriers of α-thalassemia, of whom 81 (4.5 percent) were carriers of the Southeast Asian type of deletion, in which both α-globin genes on the same chromosome 16 are deleted. Sixty-one students (3.4 percent) were carriers of either β-thalassemia or the mutation coding for hemoglobin E. Six students were carriers of both α- and β-thalassemias. On the basis of these figures, the estimated numbers of pregnancies in Hong Kong in which the fetus is at risk for homozygous α-thalassemia and β-thalassemia major or intermedia are 145 and 80 per year, respectively. In Hong Kong the actual numbers of women referred for prenatal diagnoses of these disorders are approximately 95 and 40 per year, respectively. Conclusions: Despite the availability of hospital-based screening and prenatal diagnosis for many years in Hong Kong, many women carrying fetuses at risk for thalassemia are not referred for genetic counseling. A community-based program of education, screening, and counseling is needed in Hong Kong and southern China.published_or_final_versio

Change of the emission spectra in organic light-emitting diodes by layer thickness modification

The electroluminescence (EL) and photoluminescence properties of organic light-emitting diodes (LED) were analyzed using layer thickness modification. Investigations show that the EL spectra exhibited significant variation with the increase of the viewing angle. It was found that multiple peak emission could be achieved for a certain range of thickness values. It was concluded that near white emission with CIE coordinates (0.32, 0.43) could be obtained for optimized device thickness.published_or_final_versio

Response to ''Comment on 'Change of the emission spectra in organic light-emitting diodes by layer thickness modification''' Appl. Phys. Lett. 86, 186101.2005.

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Psychotropic medicine consumption in 65 countries and regions, 2008–19: a longitudinal study.

BACKGROUND: The WHO Comprehensive Mental Health Action Plan 2013–2030 encourages routine collection and reporting of a set of essential mental health indicators, including the availability of psychotropic medicines. The global monitoring of country-level psychotropic medicine consumption trends can provide information on the extent of the availability of psychotropic medicines. The primary objective of this study was to investigate global trends in psychotropic medicines consumption from 2008 to 2019 across 65 countries and regions according to country income level and geographical region. METHODS: In this longitudinal trends study, we used pharmaceutical sales data from the IQVIA-Multinational Integrated Data Analysis System (IQVIA-MIDAS). We analysed monthly sales data of psychotropic medicines between Jan 1, 2008, and Dec 31, 2019. Total psychotropic medicine consumption included sales of antidepressants, antipsychotics, tranquilisers, sedatives or hypnotics, and mood stabilisers. Population estimates of each country or region (eight lower-middle-income countries, 19 upper-middle-income countries, and 38 high-income countries) were based on the UN World Population Prospects 2019 report. Average annual sales trends of psychotropic medicines, expressed as defined daily dose (DDD) per 1000 inhabitants per day, were estimated using a random-effects model adjusted for income level and region. Relative changes in the annual consumption of psychotropic medicines by income, expressed as DDD per 1000 inhabitants per day, were assessed as percentage change for each medicine class. FINDINGS: Psychotropic medicine sales increased from 28·54 DDD per 1000 inhabitants per day in 2008 to 34·77 DDD per 1000 inhabitants per day in 2019, corresponding to a 4·08% (95% CI 2·96–5·21) relative average increase annually. The absolute annual increase was greater in high-income countries (3·31 DDD per 1000 inhabitants per day, 95% CI 3·01–3·61) compared with upper-middle-income countries (1·94 DDD per 1000 inhabitants per day, 1·45–2·44) and low-middle-income countries (0·88 DDD per 1000 inhabitants per day, 0·62–1·13; p<0·0001). The relative average annual increase in psychotropic medicine sales from 2008 to 2019 was greater in upper-middle-income countries (7·88%, 95% CI 6·99–8·77) than in lower-middle-income countries (2·90%, 2·40–3·39) and high-income countries (1·02%, 0·80–1·24). In 2019, the regional consumption of psychotropic medicines varied greatly, with the highest sales of all psychotropic medicine classes reported in northern America (167·54 DDD per 1000 inhabitants per day) and lowest sales reported in Asia (5·59 DDD per 1000 inhabitants per day). 17 countries had very low consumption of psychotropic medicines in 2019, including high-income countries and countries with a high prevalence of mental disorders. INTERPRETATION: The consumption of psychotropic medicines has increased over a 12-year period, and although the absolute growth rate was highest in high-income countries, the relative growth is highest in middle-income countries and especially upper-middle-income countries. Disparities in psychotropic medicine consumption of countries can only partly be explained by geographical location and income. Greater efforts are needed to increase the availability of psychotropic medicines in countries with very low consumption, which is probably due to financial or cultural reasons as well as scarcity of trained health-care professionals to prescribe psychotropic medicines