Papers by Keyword: Isolation

Abstract: The paper presents research of the possibility of using potassium carbonate and bicarbonate as inhibitors in the compositions of aqueous fire-extinguishing substances for the elimination of fires associated with the burning of solid and liquid combustible materials. It has been shown theoretically and experimentally that both potassium carbonate and bicarbonate are highly effective in inhibition of chain reactions in the gas phase of flame combustion. Recommendations on the selection of the inhibitory component when creating compositions of aqueous fire extinguishing substances are given.

Abstract: The present work represents polarization reconfigurable MIMO antenna which is design to work at 2.4 GHz (WLAN) and C band application. An inverted U-shaped slot and two PIN diodes per radiator are incorporated in the circular patch antenna to achieve polarization reconfigurability between Linear and Circular polarization (RHCP or LHCP). A simple rectangular strip is utilized between the radiators to achieve isolation improvement from -14 dB to -22dB in the proposed design. Computer Simulation Technology (CST) 2018 is used to design and validate the polarization reconfigurable MIMO antenna with sufficient isolation. Surface current distribution, Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) and axial ratio are calculated using simulation software and used to validate circularly polarized MIMO design’s diverse behavior. The design is fabricated in low-cost FR-4 material and measurement is done to verify the simulation results. The measurement results show close agreement with simulated results and proves that the proposed design can be a better candidate for WLAN and C band application with polarization reconfiguration properties.

Abstract: У даному дослідженні представлені можливості використання вогнегасної речовини на основі водорозчинного полімеру для ліквідації пожеж на полігонах ТПВ та полігонах побутових відходів, пожежне навантаження яких утворюється за рахунок твердих горючих матеріалів. Теоретично та експериментально показано, що шляхом зміни концентрації гелеутворювальних добавок можна змінювати в'язкість, що безпосередньо впливає на швидкість випаровування та глибину проникнення вогнегасної речовини в осередок пожежі. Наведено результати експериментальних досліджень ефективності гелевих вогнегасників на основі полімеру ECOFLOC A-07.

Abstract: 4H Silicon Carbide multichannel neural interface devices using NPN junctions for channel isolation were fabricated using four different doping structures. Two devices used thicker, lower-doped epitaxial layers, one used thin, highly-doped implanted layers implanted into a N epilayer, and one used thin-highly-doped implanted layers into an N substrate. The devices were characterized in terms of resistance, charge delivery, leakage current through the substrate, and crosstalk between channels. The thickest, lower-doped epitaxial layers performed best, resulting in great isolation and good performance. While the implanted layers showed high charge delivery, their resistance is reduced due to the thin layers and the isolation is particularly poor.

Abstract: У даній роботі представлено спосіб створення гелевої вогнегасної речовини на основі гідроксиду алюмінію з використанням карбонату калію. Показано переваги запропонованого способу порівняно з відомим способом створення гелевої вогнегасної речовини на основі гідроксиду алюмінію з використанням карбонату натрію. Наведено результати експериментальних досліджень ефективності гелевогнегасних речовин на основі гідроксиду алюмінію.

Abstract: The contributions balance of isolation and cooling effects relative to the liquids surface to slow down their evaporation and to achieve safe vapor concentrations is determined. The influence of liquids characteristic temperatures and their water solubility on this process is considered. It is proven that the long-term effect of such means is provided by systems based on closed-pore floating solid materials (for example, foam glass). It is proposed to increase the foam glass low isolation and cooling capacity either by coating it with an inorganic gel or by wetting it with water. Smaller evaporation retardation coefficients by gel were obtained for liquids with the higher water solubility. A 5–6 times greater cooling capacity of the wet foam glass than dry foam glass was obtained for both polar and non-polar liquids. A smaller cooling effect is observed for liquids with a higher vaporization heat and is similar for both the use of the dry and wet foam glass. It was found that for low-boiling non-polar liquids, the evaporation slowing down is more effectively achieved by using isolation effects, and for high-boiling polar and non-polar liquids - by using cooling effects. It is proved that the fire extinguishing effect by applying the foam glass layer on the flammable liquid surface occurs in a similar way for liquids with close equivalent cluster lengths and not flash temperatures.

Abstract: Extinguishing fires in ecosystems has features compared to extinguishing fires in residential and industrial buildings, due to the composition and structure of combustible materials, which can form many foci of smoldering and have the ability to re-ignite, have a relatively low fire load compared to man-made ones. All this leads to high costs of water for extinguishing, carrying out operations for additional extinguishing of fires that occur after the main extinguishing and sets special requirements for aqueous extinguishing agents for their extinguishing.The paper analyzes the current state of the availability and trends of development in the world and domestic practice of effective water extinguishing agents and technologies for their use. Possible ways to improve recipes and increase the efficiency of fire extinguishing substances are outlined, taking into account, first of all, the criteria of efficiency, economy and environmental friendliness.It is noted that the main direction of increasing the fire extinguishing capacity of water is to create combined fire extinguishing solutions that can combine several methods of extinguishing in one technological operation: cooling, isolation and inhibition, which, other things being equal, reduces fire extinguishing consumption and extinguishing efficiency. An integrated direction of increasing the fire-extinguishing capacity of water can be considered to increase the coefficient of active use of water by reducing the surface tension of the fire-extinguishing solution, increasing the wettability and viscosity of water by introducing appropriate additives, obtaining optimal droplet dispersion.

Abstract: Kratom (Mitragyna speciosa Korth) leaves contain a major alkaloid, mitragynine, which has opioid pain-relieving activity. Kratom and its derivatives are abused as alternatives to other narcotics. Therefore, this preliminary study was aimed to optimize the extraction of mitragynine from kratom investigating the effect of extraction time and ultrasonication on yield and quality of extract (the content of mitragynine). The extraction was carried out sequential extraction at room temperature and treatment of ultrasonication before extraction which was followed the purification process. Ultrasound-assisted extraction increased mitragynine yield to16.88%, compared to extraction without ultrasonication. The extract was purified by column chromatography, eluted with a mixture of n-hexane - ethyl acetate - 25% ammonia with a ratio of 30:15:1 (v/v). Likewise, the highest mitragynine purity obtained was 86.46%.

Abstract: Plant Rumput Mutiara (Hedyotis corymbosa (L.) Lamk) is one of the family species of Rubiaceae which is used as a traditional medicine that is effective in healing boils, acne, anti-inflammatory, and anticancer. Research methods include maceration, fractionation, purification, class test and bioactivity test with Kirby-Bauer diffusion method using E.coli bacteria. The results of this research are pure isolates with white crystal needle shape with melting point 137-138°C. Pure isolates were analyzed using FTIR, and by the IR spectrum which showed the absorption band at wave numbers 3435.22 cm-1 indicated the presence of –OH, CH₃ and-CH₂- aliphatic groups (2956.87 cm-1; 2935.66 cm-1; 2893.22 cm-1; and 2866.22 cm-1), C = C (1641.42 cm^-1), -CH₃ and-CH₂- bending (1462.04 cm^-1 and 1377.17 cm^{- 1}), CO (1056.99 cm^-1), and = CH (964.41 cm^-1). Based on the result, it showed that the isolate was steroid group which has low antibacterial activity againts E.coli with inhibition power of 10 mm.

Abstract: A highly efficient lambda-cyhalothrin-degrading bacterium, designated as strain ZC-5, was isolated from the activated sludge of a sewage aeration tank in a pesticide factory by enrichment acclimation and the streak plate method. Strain ZC-5 can grow on minimal medium with lambda-cyhalothrin as the sole source of carbon and nitrogen. After cultivation for 6 h to 24 h, the biomass of the bacterial strain significantly increased at the logarithmic phase. By contrast, the concentration of lambda-cyhalothrin rapidly decreased. The residual lambda-cyhalothrin presented a concentration of 250 mg/L and a degradation rate of 50%. Gas chromatography revealed that this strain can degrade 87.1% lambda-cyhalothrin (500 mg/L) in the culture within 2 days. Morphological analysis showed the Gram-negative strain as short rods. Physiological and biochemical characterizations, as well as phylogenetic analysis of the 16S rDNA sequence identified the bacterium to be an Achromobacter xylosoxidans strain. Results showed that this strain can provide a novel strategy to biodegrade the pesticide lambda-cyhalothrin.