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31.
Bose Narayanasamy Aniruthan Saran Vignesh kumar 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(21):2572-2579
A rapid decrease in the availability of non-renewable fossil fuels has initiated the search for alternative fuels. Biodiesel obtained from various feedstocks has proved to be an effective alternative source for diesel engines due to its convincing fuel characteristics. The oxidation property of biodiesel is influenced by external factors such as sunlight and exposure to atmosphere.The oxidation stability of biodiesel can be improved by the addition of antioxidants which may be synthetic or natural. Natural antioxidants are more effective than synthetic ones in terms of economic value as well as prevention of adverse carcinogenic effects. Natural antioxidants, namely, ginger, Moringa oleifera, oregano, basil, and clove were extracted and used for the present study. The antioxidant activity of the additives was analyzed by DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging activity. The DPPH scavenging effect was calculated in terms of % by using absorbance values recorded with UV spectrophotometer. Among the antioxidants used, clove additive was found to be more efficient in enhancing the oxidation stability, with scavenging effect of 42.23%, 47.67%, 51.62%, and 55.61% for 500, 1000, 1500, and 2000 ppm, respectively. It was also observed that the scavenging activity increased with the concentration of antioxidant additives, and the maximum value was recorded at a concentration of 2000 ppm. Mahua oil methyl ester (MOME) was selected as biodiesel for the present study for which the oxidation stability has to be evaluated. The oxidation stability of MOME was measured in terms of induction period using the Rancimat method which does not meet the required standards. The oxidation stability of MOME, MOME + ginger 2000, MOME + M. oleifera 2000, MOME + oregano 2000, MOME + basil 2000, and MOME + clove 2000 was evaluated. The highest induction period was observed to be 38.44 h for MOME + clove 2000 blend. Hence, clove additive was found to be more effective among the selected natural antioxidants in terms of increasing the scavenging effect as well as increasing the oxidation stability of MOME. Thus, the addition of natural antioxidants can be recommended to improve the oxidation stability of biodiesel based on their scavenging effect which can be further validated by means of the Rancimat method in terms of the induction period 相似文献
32.
H Sladowska J Stanasiuk M Sieklucka-Dziuba T Saran Z Kleinrok 《Canadian Metallurgical Quarterly》1998,53(7):475-479
Synthesis of 4-aminosubstituted 2,6,7-trimethyl-1,5-dioxo-1,2,5,6-tetrahydropyrido[3,4-d]pyridazin es 2-11 and the results of the preliminary pharmacological screening of the selected compounds 2, 4, 5, 10, 11 are described in this paper. 相似文献
33.
Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering
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Ananth Saran Yalamarthy Hongyun So Miguel Muñoz Rojo Ateeq J. Suria Xiaoqing Xu Eric Pop Debbie G. Senesky 《Advanced functional materials》2018,28(22)
Progress in wide bandgap, III–V material systems based on gallium nitride (GaN) has enabled the realization of high‐power and high‐frequency electronics. Since the highly conductive, 2D electron gas (2DEG) at the aluminum gallium nitride (AlGaN)/GaN interface is based on built‐in polarization fields and is confined to nanoscale thicknesses, its charge carriers exhibit much higher mobilities compared to their doped counterparts. This study shows that such 2DEGs also offer the unique ability to manipulate electrical transport separately from thermal transport, through the examination of fully suspended AlGaN/GaN diaphragms of varied GaN buffer layer thickness. Notably, ≈100 nm thin GaN layers can considerably impede heat flow without electrical transport degradation. These achieve 4× improvement in the thermoelectric figure of merit (zT) over externally doped GaN, with state‐of‐the‐art power factors of 4–7 mW m‐1 K‐2. The remarkable tuning behavior and thermoelectric enhancement, elucidated here for the first time in a polarization‐based heterostructure, are achieved because electrons are at the heterostructured interface, while phonons are within the material system. These results highlight the potential for using 2DEGs in III–V materials for on‐chip thermal sensing and energy harvesting. 相似文献
34.
Dynamic Probabilistic Caching Algorithm with Content Priorities for Content‐Centric Networks
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Warit Sirichotedumrong Wuttipong Kumwilaisak Saran Tarnoi Nattanun Thatphitthukkul 《ETRI Journal》2017,39(5):695-706
This paper presents a caching algorithm that offers better reconstructed data quality to the requesters than a probabilistic caching scheme while maintaining comparable network performance. It decides whether an incoming data packet must be cached based on the dynamic caching probability, which is adjusted according to the priorities of content carried by the data packet, the uncertainty of content popularities, and the records of cache events in the router. The adaptation of caching probability depends on the priorities of content, the multiplication factor adaptation, and the addition factor adaptation. The multiplication factor adaptation is computed from an instantaneous cache‐hit ratio, whereas the addition factor adaptation relies on a multiplication factor, popularities of requested contents, a cache‐hit ratio, and a cache‐miss ratio. We evaluate the performance of the caching algorithm by comparing it with previous caching schemes in network simulation. The simulation results indicate that our proposed caching algorithm surpasses previous schemes in terms of data quality and is comparable in terms of network performance. 相似文献
35.
36.
Sunil K. Srivastava Tripurari Saran Jagadish Sinha Laxminarayanapuram V. Ramachandran Siripurapu K. Rao 《Fuel》1988,67(12):1680-1682
The interaction between Poniati-Girimint coal and alkali has been studied at temperatures from 400 °C to 700 °C and with various ratios of alkali to coal from O to 1.4, using a heating rare of 5 °C min−1 or shock heating at 600 °C. With slow heating, the optimum temperature and alkali to coal ratio for maximum yield of hydrogen at atmospheric pressure were 600 °C and 1.25, respectively. Under these conditions the yields of hydrogen and methane were 505 m3 and 76 m3 per tonne of coal, respectively. In shock pyrolysis the corresponding yields were 370 m3 and 34 m3 per tonne of coal, respectively. The recovery of alkali was 87%, 13% having reacted with the mineral matter of the coal. X-ray diffraction and infrared studies of the washed residual char indicated that the mineral matter present was highly dispersed and had probably been converted into sodium and aluminosilicates. 相似文献
37.
Wenhu Zhou Runjhun Saran Po‐Jung Jimmy Huang Prof. Dr. Jinsong Ding Prof. Dr. Juewen Liu 《Chembiochem : a European journal of chemical biology》2017,18(6):518-522
Ca2+ is a highly important metal ion in biology and in the environment, and thus there is extensive work in developing sensors for Ca2+ detection. Although many Ca2+‐binding proteins are known, few nucleic acids can selectively bind Ca2+. DNA‐based biosensors are attractive for their high stability and excellent programmability. We report a RNA‐cleaving DNAzyme, EtNa, cooperatively binding two Ca2+ ions but to only one Mg2+. Four DNAzymes with known Ca2+‐dependent activity were compared, and the EtNa had the best selectivity for Ca2+. The EtNa is 90 times more active in Ca2+ than in Mg2+. Phosphorothioate (PS) modification showed that both non‐bridging oxygen atoms at the scissile phosphate contribute equally to Ca2+ binding. The pH–rate profile suggests two concurrent deprotonation reactions. EtNa was further engineered for Ca2+ sensing, and found to have a detection limit of 17 μm Ca2+ and excellent selectivity. The detection of Ca2+ in tap water was performed, and the result was comparable with that by ICP‐MS. This study offers new fundamental insights into Ca2+ binding by nucleic acids and improved metal selectivity by having multiple cooperative metal binding sites. 相似文献
38.
Xunet 2 is a collaborative research program with a goal of understanding the fundamental issues in the performance of ATM networks. These networks are expected to carry a mixture of constant bit-rate traffic, variable bit-rate traffic and computer traffic spanning a wide range of performance requirements. This paper describes these service requirements and matches them with performance guarantees that can be provided by the scheduling discipline supported by an experimental ATM switch. The scheduler supports per-virtual-circuit queueing and several priorities of round robin service in order to segregate real-time and non-real-time traffic and provide fair sharing for bursty computer traffic. Detailed simulations show that real-time traffic can be efficiently integrated with non-real-time traffic using appropriate call admission policies and enhancements to traditional round robin scheduling. While the present study focuses on providing quality of service guarantees in the Xunet 2 network, the design of the scheduler and the call admission policies are relevant to ATM networks in general.
On leave of: Indian Institute of Technology, Delhi, India 相似文献
39.
Eleven patients in remission from manic-depressive illness were studied by means of metabolic balances before and after the administration of lithium carbonate. Lithium caused a sharp diuresis of isotonic saline and a smaller excretion of potassium over the course of two days. During the subsequent two days there occurred a compensatory retention of Na, K and water. These short-term changes were not associated with any significant alteration in the patients' mood. There was no significant and systematic retention of Na, K or water over the 14 days of Li administration. The recovery of Li was measured simultaneously. During the first week only a proportion of the administered Li was recovered in the urine and faeces, suggesting that a gradual distribution of Li throughout its body space was occurring. After the first week, nearly all the administered Li was recovered, indicating an equilibrium with an even distribution of the ion throughout its body space. This equilibrium was more complete at this early stage in those patients who had been given a smaller dose of lithium carbonate. 相似文献
40.
Leitner G Merin U Silanikove N Ezra E Chaffer M Gollop N Winkler M Glickman A Saran A 《The Journal of dairy research》2004,71(3):311-315
The study was aimed at identifying the pathogens causing subclinical udder infections in representative Israeli dairy goat herds and determining their effect on milk quality. Five hundred goats in ten flocks of various breeds and crossbreeds were surveyed. Of the 500 goats, 13.4% were in their first lactation, 36.4% were in their second lactation and 50.2% were in their third or higher lactation. Percentages of udder halves with subclinical intramammary infection in the flocks ranged from 35 to 71%. The effect of the bacteriological infection on somatic cells count (SCC) was significant (P<0.001). Various species of coagulase-negative staphylococci (CNS), mainly Staphylococcus caprae and Staphylococcus epidermidis, were the main pathogens in infected udder halves. Lactation number did not significantly influence either infection rate of udder halves or SCC, although the percentage of udder halves with no bacteriological findings was higher at the first lactation than at the third lactation. Milk composition (fat, protein and lactose) varied among flocks, with lower mean total protein in uninfected halves than in infected ones and higher lactose in uninfected than infected halves. 相似文献