Absorption and luminescence of hydrogen and oxygen passivated silicon quantum dots

Silicon (Si) quantum dots (QDs) passivated with oxygen and hydrogen of size 1 nm in diameter are prepared by wet chemical route and electrochemical route respectively. The optical measurements reveal the strong absorption feature around 4.7 eV and weak absorption at 3.4 eV for oxygen passivated Si QDs. Hydrogen passivated Si QDs of the same size show absorption at 4.9 eV. Both the oxygen and hydrogen passivated Si QDs show broad luminescence around 3.9 and 3.8 eV. Films of these QDs, when coated on crystalline silicon solar cells, show an increase in the efficiency of the solar cell by 12 %. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2788

Magnetic Behavior of Manganese-Doped ZnSe Quantum Dots

Magnetic properties of manganese-doped ZnSe quantum dots with the size of approximately 3.6 nm are investigated. The amount of Mn in the ZnSe quantum dots has been varied from 0.10% to 1.33%. The doping level in the quantum dots is much less than that used in the precursor. The co-ordination of Mn in the ZnSe lattice has been determined by electron paramagnetic resonance (EPR). Two different hyperfine couplings 67.3×10−4 and 60.9×10−4 cm−1 observed in the EPR spectrum imply that Mn atoms occupy two distinct sites; one uncoordinated (near the surface) and other having a cubic symmetric environment (nanocrystal core), respectively. Photoluminescence measurements also confirm the incorporation of Mn in ZnSe quantum dots. From the Curie-Weiss behavior of the susceptibility, the effective Mn-Mn antiferromagnetic exchange constant (J1) has been evaluated. The spin-glass behavior is observed in 1.33% Mn-doped ZnSe quantum dots, at low temperature. Magnetic behavior at a low temperature is discussed

ANTIFUNGAL APPRAISAL OF BURKHOLDERIA GLADIOLI STRAIN VIMP03 (JQ867372) AGAINST CERATOCYSTIS PARADOXA

ABSTRACTObjective: The purpose of the present investigation was to assess antifungal characterization of Burkholderia gladioli strain VIMP03 (JQ867372), anisolate from sugar beet rhizosphere.Methods: Antifungal characterization was carried out by biochemical, dual culture, and agar well diffusion methods against Ceratocystis paradoxa, asoilborne pathogen of sugarcane and other crops. Culture filtrate and ethyl acetate extract obtained from culture supernatant were analyzed by highperformanceliquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) analyses, respectively.Results: The culture filtrate and ethyl acetate extract exhibited effective antifungal activity. Organic acid profile of the culture filtrate was determined.Acetic acid was mainly produced by the culture under study. The GC-MS analysis of ethyl acetate extract documented the presence of compoundsincluding tetratetracontane, 9-nonadecene, erucic acid, and other hydrocarbon derivatives.Conclusion: The GC-MS, HPLC, and biochemical profiles of B. gladioli strain VIMP03 (JQ867372) revealed its agro clinical-antifungal potential.Keywords: Antifungal, Burkholderia gladioli, High-performance liquid chromatography, Gas chromatography-mass spectrometry

Design and Analysis of Four Wheeled Electrically Powered Mobility Vehicle

People with movement disabilities have numerous challenges in life, two of the most significant of which are first dependency on others and secondly mobility restrictions. As a result, people are unable to enjoy simple and personal activities such as shopping, going for a drive, riding on off-road terrain, and going on camping vacations, among other things. Though there are already various solutions available, such as wheelchairs, manual and electric wheelchairs, in this paper, we design and develop an open, four-wheeled, electrically powered mobility vehicle to address the aforementioned difficulties. This approach will seek to address the inadequacies of present choices by offering people with movement limitations a secure, comfortable, and relatively cost-effective form of transportation. The goal of this project is to include the advantages of current available options, such as wheelchair seating, compact design of mobility scooters and wheelchairs, electric power source and speed of mobility scooters, and overcome their challenges, such as long range, more speed, stability of a four-wheeled chassis, off-road driving capability, sufficient storage space, comparable price range, and so on

A review of combined advanced oxidation technologies for the removal of organic pollutants from water

Water pollution through natural and anthropogenic activities has become a global problem causing short-and long-term impact on human and ecosystems. Substantial quantity of individual or mixtures of organic pollutants enter the surface water via point and nonpoint sources and thus affect the quality of freshwater. These pollutants are known to be toxic and difficult to remove by mere biological treatment. To date, most researches on the removal of organic pollutants from wastewater were based on the exploitation of individual treatment process. This single-treatment technology has inherent challenges and shortcomings with respect to efficiency and economics. Thus, application of two advanced treatment technologies characterized with high efficiency with respect to removal of primary and disinfection by-products in wastewater is desirable. This review article focuses on the application of integrated technologies such as electrohydraulic discharge with heterogeneous photocatalysts or sonophotocatalysis to remove target pollutants. The information gathered from more than 100 published articles, mostly laboratories studies, shows that process integration effectively remove and degrade recalcitrant toxic contaminants in wastewater better than single-technology processing. This review recommends an improvement on this technology (integrated electrohydraulic discharge with heterogeneous photocatalysts) viz-a-vis cost reduction in order to make it accessible and available in the rural and semi-urban settlement. Further recommendation includes development of an economic model to establish the cost implications of the combined technology. Proper monitoring, enforcement of the existing environmental regulations, and upgrading of current wastewater treatment plants with additional treatment steps such as photocatalysis and ozonation will greatly assist in the removal of environmental toxicants

Effect of [OH-] linkages on luminescent properties of ZnO nanoparticles

Optical properties of ZnO nanoparticles prepared from a simple chemical method using sodium zincate bath show strong white light emission. X-ray absorption fine structure studies reveal a completely different local environment around Zn in these ZnO nanoparticles. The observed luminescence properties and local structural changes have been explained on the basis of a linkage between Zn and OH- ions in the surface layers of ZnO nanoparticles.Comment: J. Phys. Chem. C. (2011) (in print

Treatment of persistent organic pollutants in wastewater using hydrodynamic cavitation in synergy with advanced oxidation process

Persistent organic pollutants (POPs) are very tenacious wastewater contaminants. The consequences of their existence have been acknowledged for negatively affecting the ecosystem with specific impact upon endocrine disruption and hormonal diseases in humans. Their recalcitrance and circumvention of nearly all the known wastewater treatment procedures are also well documented. The reported successes of POPs treatment using various advanced technologies are not without setbacks such as low degradation efficiency, generation of toxic intermediates, massive sludge production, and high energy expenditure and operational cost. However, advanced oxidation processes (AOPs) have recently recorded successes in the treatment of POPs in wastewater. AOPs are technologies which involve the generation of OH radicals for the purpose of oxidising recalcitrant organic contaminants to their inert end products. This review provides information on the existence of POPs and their effects on humans. Besides, the merits and demerits of various advanced treatment technologies as well as the synergistic efficiency of combined AOPs in the treatment of wastewater containing POPs was reported. A concise review of recently published studies on successful treatment of POPs in wastewater using hydrodynamic cavitation technology in combination with other advanced oxidation processes is presented with the highlight of direction for future research focus