Hybrid technology for the use of solar energy : the challenge towards green energy / S. I. Hossain ... [et al.]

Large areas in many countries are populated but have no connection to a national electricity grid. Centralized electricity generating facilities burning fossil fuels have been the normal. Renewable energy resources, especially solar energy is now penetrating this sector. Long-term energy storage is the universal challenge in providing renewables-based electricity with high availability across the seasons. Solar domestic hot water system is widely used and developing fast in recent years. However many problems occur at the same time, for example more energy consumption by circulation pump, water reheating, long investment payback period, and etc. The motivation for the development of a combined hot water and sorption store is to complement the advantages and to reduce the disadvantages of the two particular storage technologies. Hot water stores offer high heat supply rates but are particularly suitable for short term storage due to heat losses whereas for a sorption store the power drain is low but it shows the advantage of a high storage density and long-term heat storage almost without losses. We investigated the demonstration project and discuss the need for authoritative system modelling in order to size the system components for minimum cost at a designated availability of supply

Organochlorine pesticide residues in poultry meats of Bangladesh

Forty poultry meat samples from four large companies were analyzed for the presence of organochlorine pesticides. Homogenized samples were mixed with silica sand and anhydrous sodium sulfate, and extracted with ethyl acetate followed by n-hexane: MTBE. Clean up of samples were done by silica sulphuric acid and analyzed by GC-ECD, and confirmed by GC-MS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.5, 0.5 and 0.7, and 2.5, 2.5 and 3.5 ng/g, respectively. The calibration curves were linear and the correlation coefficients (r2) were 0.991, 0.992 and 0.997 for DDE, DDD and DDT, respectively and the recoveries for them were 76%, 78% and 80%. DDT and its metabolites, DDE and DDD were detected in 28 (70%), out of 40 samples and ranged 0.039-0.769 mg/kg

Oblique propagation of arbitrary amplitude electron acoustic solitary waves in magnetized kappa-distributed plasmas

The linear and nonlinear properties of large amplitude electron-acoustic waves are investigated in a magnetized plasma comprising two distinct electron populations (hot and cold) and immobile ions. The hot electrons are assumed to be in a non-Maxwellian state, characterized by an excess of superthermal particles, here modelled by a kappa-type long-tailed distribution function. Waves are assumed to propagate obliquely to the ambient magnetic field. Two types of electrostatic modes are shown to exist in the linear regime, and their properties are briefly analyzed. A nonlinear pseudopotential type analysis reveals the existence of large amplitude electrostatic solitary waves and allows for an investigation of their propagation characteristics and existence domain, in terms of the soliton speed (Mach number). The effects of the key plasma configuration parameters, namely, the superthermality index and the cold electron density, on the soliton characteristics and existence domain, are studied. The role of obliqueness and magnetic field are discussed.Comment: Submitted to Plasma Physics and Controlled Fusio

Electron-acoustic plasma waves: oblique modulation and envelope solitons

Theoretical and numerical studies are presented of the amplitude modulation of electron-acoustic waves (EAWs) propagating in space plasmas whose constituents are inertial cold electrons, Boltzmann distributed hot electrons and stationary ions. Perturbations oblique to the carrier EAW propagation direction have been considered. The stability analysis, based on a nonlinear Schroedinger equation (NLSE), reveals that the EAW may become unstable; the stability criteria depend on the angle $\theta$ between the modulation and propagation directions. Different types of localized EA excitations are shown to exist.Comment: 10 pages, 5 figures; to appear in Phys. Rev.

Synthesis, Characterization and Bioactivities of Some Novel Oxovanadium(IV) Glycinato Complexes

The novel oxovanadium(IV) complexes, [VIVO(GlyH)(Gly)]+ClO4 - .H2O (1), [VIVO(GlyH)(Gly)]+NO3 - .H2O (2), [VIVO(GlyH)(Gly)]+CH3COO- .H2O (3) were synthesized and characterized by FT-IR, UV-Vis and 1H NMR spectroscopic measurements. The cumulative spectroscopic assessment envisaged that, the complexes adopt a square pyramidal structure, in which the two glycine ligands coordinate to vanadium(IV) center in bidentate fashions conforming a homoleptic structure. The amino nitrogen and a carboxylato oxygen atom coordinate the vanadium(IV) center from both sides making a five members chelate by each side. All the complexes are stable in amorphous state and in aerobic and anaerobic solution. Significantly, all the complexes have the antifungal activities against Aspergillus niger and Penicillium notatum but ineffective against Candida tropicalis. No antibacterial activity was observed for the complexes against tested bacteria and unfortunately, they were found cytotoxic against brine shrimp bioassay

Size effects in compression in Electron Beam Melted Ti6Al4V diamond structure lattices

In experimental work on the mechanical properties of stochastic metal foams, the consensus is that a minimum of six pores along each direction are required to give representative mechanical properties. This theory is tested for another porous metal, regular lattices, built using repeating unit cells of the diamond structure (a tetrahedral structure, in a cubic formation) by Electron Beam Melting (EBM) from grade 5 Ti6Al4V. Samples with different numbers of unit cells are made, using 3 different sets of EBM manufacturing conditions, and tested in compression. In all cases, a minimum of four unit cells are needed to ensure that size-independent mechanical properties are measured. Small changes in manufacture lead to large differences in properties

Enhanced Case Detection and Improved Diagnosis of PKDL in a Kala-azar-Endemic Area of Bangladesh

PKDL is a skin disorder which usually develops in 10–20% and about 60% of patients with visceral leishmaniasis (VL) after treatment respectively in the Indian subcontinent and Sudan. However, cases among people without prior VL have also been reported. Except skin lesion, PKDL patients are healthy and usually do not feel sick. However, persistence of a few PKDL cases is sufficient to initiate a new epidemic of anthroponotic VL. Thus, identifying and treating people with PKDL is a key strategy for the elimination of kala-azar. Diagnosis of PKDL relies upon clinical criteria and a serological test which is not specific for PKDL. The use of the existing laboratory diagnostic tools for confirmation of PKDL among PKDL suspects is unknown. In the Indian subcontinent, PKDL is not self-limited and needs to be treated with sodium stibogluconate injections for 4–6 months. No data are available relating to treatment compliance by patients, particularly in Bangladesh. The results of the present study showed that trained village volunteers were useful for identifying PKDL suspects, and diagnostic confirmation improved with the use of PCR. However, patients' adherence to prescribed treatment was poor

Prevalence and factors associated with depression and suicidal ideation during the COVID-19 pandemic among university students in Uganda: a cross-sectional study

Background: The COVID-19 pandemic has negatively impacted psychosocial well-being and mental health of students across the world. Although students are vulnerable to depression and suicidal ideation, few studies have been conducted in Uganda. This study aimed to determine the prevalence of depression and suicidal ideation, and associated factors among undergraduate university students in Uganda. Methods: A cross-sectional study was conducted among undergraduates [N = 540; 363 males; mean age = 23.3 (± 2.64) years] recruited from four universities using an online questionnaire that explored sociodemographic factors, depression, and other associated factors. The Patient Health Questionnaire (PHQ-9) was used to assess depression, and Item 9 was used to assess suicidal ideation in the past 2 weeks. Multivariable logistic regression analyses were performed to determine the factors associated with depression and suicidal ideation. Results: The prevalence of moderate to severe depression was 20% (n = 108) (cut-off: 10/27 based on the PHQ-9), and the prevalence of past-2-week suicidal ideation was 13.89% (n = 75) (cut-off: 1/3 based on the PHQ-9 Item 9). About half of the individuals who screened positive for depression had suicidal ideation. Factors associated with depression were: having relationship issues [adjusted odds ratio (aOR) = 1.79, 95% confidence interval (CI) = 1.13–2.81, p = 0.012], and having a history of sexual abuse (aOR = 2.06, 95% CI = 1.10–3.84, p = 0.023). Factors associated with reducing the risk of depression were: satisfaction with current academic performance (aOR = 0.50, 95% CI = 0.32–0.79, p = 0.003), and being in the fifth year of academic study (aOR = 0.16, 95% CI = 0.03–0.73, p = 0.018). Factors associated with suicidal ideation were: smoking cigarettes and/or marijuana (aOR = 4.83, 95% CI = 1.10–21.12, p = 0.037), and having financial tuition constraints (aOR = 1.85, 95% CI = 1.08–3.16, p = 0.024), However, satisfaction with current academic performance reduced the likelihood of suicidal ideation (aOR = 0.40, 95% CI = 0.23–0.70, p = 0.001). Conclusion: Approximately one-fifth of undergraduate university students were moderately to severely depressed, especially those who had relationship issues and those with a history of sexual abuse. Suicidal ideation was common among smokers and those having financial tuition constraints. Therefore, it is recommended that the university authorities implement measures to provide psychological support for the students with problems concerning financial tuition constraints, relationships, and sexual abuse. Also, all students with depression should be screened for suicidality

Suicidal behaviours among Ugandan university students: a cross-sectional study

Background: Suicide remains the leading cause of death among university students often resulting from multiple physical and psychological challenges. Moreover, suicidal behaviours among students appear to have increased due to the COVID-19 pandemic according to some studies. Objective: To explore the prevalence and associated factors for suicidal ideation, suicide plans, and suicide attempts among university students in Uganda. Methods: Cross-sectional study data were collected from May to September 2021 from 540 undergraduate university students in south-western Uganda (363 males, mean age 23.3 years). Questions from the General Health Questionnaire (GHQ-28) were used to assess suicidal ideation, while other bespoke questions were used to assess suicide plans and attempts. The survey also investigated the suicide attempt/plan method, location of the suicidal activity, and reason for not enacting the suicide plan. Three independent regression analyses were used to determine the factors associated with different forms of suicidal behaviours. Results: The prevalence of past-year suicidal behaviours was 31.85% for suicidal ideation, 8.15% for suicide plans, and 6.11% for suicide attempts. Having a chronic physical medical condition increased the likelihood of having all forms of suicidal behaviours. Suicidal ideation was associated with having difficulty paying university tuition fees. However, being in the fifth year of university education, and feeling satisfied with current academic grades reduced the likelihood of suicidal ideation. Individuals feeling satisfied with academic performance appeared to be a protective factor against having suicide plans. Suicide attempts were associated with having a history of sexual abuse and having difficulty paying university tuition fees. The most common method used for attempted suicide was a drug overdose, and the most common location for attempted suicide was their homes. Conclusion: University students have prevalent suicide behaviours especially among students with a chronic physical medical condition, a history of sexual abuse, and problems paying university tuition fees. Based on the present study, for students at risk, universities should provide appropriate interventions such as life skills education and suicide prevention techniques