OCVD Carrier Lifetime in P+NN+ Diode Structures With Axial Carrier Lifetime Gradient

The OCVD (open circuit voltage decay) method is the generally used method for the determining of carrier lifetime in the structures of semiconductor devices. This paper is focused on power diode (PCNNC) structures, in which is realised a carrier lifetime gradient to influence the current and voltage waveforms during the reverse recovery process. A theoretical analysis of the general features of voltage decay courses in OCVD measurements on diode structures with an axial carrier lifetime gradient in the diode base is presented. Some results obtained from both simulations and experimental measurements are discussed in the paper

Synthesis, Characterization and Physicochemical Properties of Biogenic Silver Nanoparticle-Encapsulated Chitosan Bionanocomposites

Green bionanocomposites have garnered considerable attention and applications in the pharmaceutical and packaging industries because of their intrinsic features, such as biocompatibility and biodegradability. The work presents a novel approach towards the combined effect of glycerol, tween 80 and silver nanoparticles (AgNPs) on the physicochemical properties of lyophilized chitosan (CH) scaffolds produced via a green synthesis method.The produced bionanocomposites were characterized with the help of Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The swelling behavior, water vapor transmission rate, moisture retention capability, degradation in Hanks solution, biodegradability in soil, mechanical strength and electrochemical performance of the composites were evaluated. The addition of additives to the CH matrix alters the physicochemical and biological functioning of the matrix. Plasticized scaffolds showed an increase in swelling degree, water vapor transmission rate and degradability in Hank\u27s balanced solution compared to the blank chitosan scaffolds. The addition of tween 80 made the scaffolds more porous, and changes in physicochemical properties were observed. Green-synthesized AgNPs showed intensified antioxidant and antibacterial properties. Incorporating biogenic nanoparticles into the CH matrix enhances the polymer composites\u27 biochemical properties and increases the demand in the medical and biological sectors. These freeze-dried chitosan-AgNPs composite scaffolds had tremendous applications, especially in biomedical fields like wound dressing, tissue engineering, bone regeneration, etc

Heat Exchanger Regulation

The work deals with the design of a laboratory task including model of heat exchanger station. It includes project documentation, with theoretical and practical part. The theoretical part is concerned with theoretical knowledge about every element used in the design. Practical part deals with the control unit of the station and the simulation of heat exchanger

Heat Exchanger Regulation

The work deals with the design of a laboratory task including model of heat exchanger station. It includes project documentation, with theoretical and practical part. The theoretical part is concerned with theoretical knowledge about every element used in the design. Practical part deals with the control unit of the station and the simulation of heat exchanger

A study of the reaction of ferrate with pentachlorophenol - kinetics and degradation products

Pentachlorophenol (PCP) is a persistent pollutant which has been widely used as a pesticide and a wood preservative. As PCP is toxic and is present in significant quantities in the environment, there is considerable interest in elimination of PCP from waters. One of the promising methods is the application of ferrate. Ferrate is an oxidant and coagulant. It can be applied as a multi-purpose chemical for water and wastewater treatment as it degrades a wide range of environmental pollutants. Moreover, ferrate is considered a green oxidant and disinfectant. This study focuses on the kinetics of PCP degradation by ferrate under different pH conditions. The formation of degradation products is also considered. The second-order rate constants of the PCP reaction with ferrate increased from 23 M(-1) s(-1) to 4,948 M(-1) s(-1) with a decrease in pH from 9 to 6. At neutral pH the degradation was fast, indicating that ferrate could be used for rapid removal of PCP. The total degradation of PCP was confirmed by comparing the initial PCP molarity with the molarity of chloride ions released. We conclude no harmful products are formed during ferrate treatment as all PCP chlorine was released as chloride. Specifically, no polychlorinated dibenzo-p-dioxins and dibenzofurans were detected

Parametry konstrukcyjne membran użytych w „inteligentnych” materiałach

Smart clothes can be described as textiles that change their behavior under some external factors (stimulants). The response of the smart cloth can be passive (just as a sensor) or active (where a combination of sensing and another reaction takes place). The materials involved in these textiles are crucial for many applications, especially for health related applications where the “wearables” can provide instantaneous monitoring and aid to people with certain disabilities. This work consists of two main parts: First it investigates the different materials used in smart clothing for monitoring the vital activities of the human body (e.g. the breathing rates) with an emphasis on piezoresistive structures as they work sensing elements for mechanical strains. Second this work presents the production of functional membrane samples based on synthesized pyrrolinone ester hydrazone dye with a preliminary investigation of their chemical and geometrical parameters, especially their sensitivity for monitoring the presence of ammonia to function as a smart textile based colorimetric chemosensor.„Inteligentne” ubrania można opisać jako tekstylia, które reagują pod wpływem czynników zewnętrznych (bodźców). Odpowiedź „inteligentnej” odzieży może być bierna (czujnik) lub czynna (wykrywanie i reakcja). Materiały związane z tymi wyrobami tekstylnymi mają kluczowe znaczenie dla wielu zastosowań, zwłaszcza dla tych związanych ze zdrowiem, gdzie odzież może zapewnić natychmiastowy monitoring i pomoc osobom niepełnosprawnym. Przedstawiona praca składała się z dwóch głównych części: najpierw badano różne materiały stosowane w „inteligentnej” odzieży do monitorowania istotnych czynności organizmu ludzkiego (np. szybkości oddychania), ze szczególnym uwzględnieniem struktur piezorezystancyjnych. W drugiej części pracy przedstawiono wytwarzanie funkcjonalnych membran z zastosowaniem syntetycznego barwnika, zbadano parametry chemiczne i geometryczne, w szczególności wrażliwości na monitorowanie obecności amoniaku w celu zastosowania wyrobu jako chemosensor kolorymetryczny

Sustainable and scalable development of PVDF-OH Ag/TiOx nanocomposites for simultaneous oil/water separation and pollutant degradation

Freshwater scarcity is a persistent global problem and is frequently worsened by contamination with oils and oil-soluble contaminants. Although the technological union of microfiltration membranes and pollutant-degrading nanoparticles are up-and-coming solutions to eliminate oils from the aquatic environment, an utterly sustainable production process enabling the transfer of these materials close to reality has not been presented so far. Here, for the first time, electrospinning and reactive laser ablation in liquids (RLAL) are combined to prepare a set of chemically stable PVDF-based membranes through a process with a favorable sustainability footprint and endowing all the features for production scale-up. The most efficient reclamation of purified water from oily wastewater was found with the membranes decorated with 2.2 wt% Ag/TiOx nanoparticles in an alkaline solution. The entire recovery process takes place in ultra-short contact times (& SIM;0.3 s), while beyond 58% of an organic pollutant (4-nitrophenol) and 80% of a tight oil emulsion (n-hexane in water) can be degraded and separated, respectively, in a continuous 20-min gravity-driven filtration. Thus, these findings provide a groundwork for the sustainable and scalable development of advanced nanotechnology for cleansing oily polluted water

Study on the field-cooling induced magnetic interactions in Gd-doped NiO nanoparticles

We herein investigate the novel magnetic interactions, such as exchange bias (EB), memory effect (ME) and magnetic relaxation dynamics (MRD) in NiO and 10 wt% Gd doped NiO nanoparticles synthesized by hydrothermal process. X-ray diffraction studies showed crystallization of face-centered-cubic structure for both NiO and Gd-doped NiO nanoparticles. Transmission electron microscopy analysis revealed a spherical morphology for both samples and their mean particle sizes were estimated as 24.5 and 10.3 nm for the pure and Gd-doped NiO nanoparticles, respectively. SQUID magnetic measurements demonstrated the occurrence of large EB coupling: 1.04 and 0.767 kOe; and enhanced coercive fields: 1.75 and 1.27 kOe, for the pure and Gd-doped NiO nanoparticles, respectively. The size-dependent magnetic properties such as, EB, ME and MRD is found to vanish at the average blocking temperature and interestingly, these properties set-in on cooling the samples at 5 K under applied field of 5 kOe. The surface defects such as oxygen vacancies and the Gd2O3 impurity phase played a significant role in determining the EB and ME characteristics of NiO nanoparticles