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排序方式: 共有860条查询结果,搜索用时 265 毫秒
71.
Chin Yung Lai Choke Fei Cheong Jit Singh Mandeep Huda Binti Abdullah Nowshad Amin Khin Wee Lai 《Journal of Materials Engineering and Performance》2014,23(10):3541-3550
The synthesis of silver nanoparticles for silver ink formation has attracted broad interest in the electronic part printing and semiconductor chip industry due to the extraordinary electrical and mechanical properties of these materials. The preparation of silver nanoparticles through a physical or chemical reduction process is the most common methodology applied to obtain nanoparticles with the required size, shape and surface morphology. The chemical solution or solvent carrier applied for silver ink formulation must be applied simultaneously with the direct writing technique to produce the desired adherence, viscosity, and reliable performance. This review paper discusses the details concerning the past and recent advancement of the synthesis and characterization of silver nanoparticles and silver ink formation. A review on the advantages of various sintering techniques, which aim to achieve the electrical and mechanical properties of the required printed structure, is also included. A brief summary concerning the recent challenges and improvement approaches is presented at the end of this review. 相似文献
72.
The catalytic generation of H2O2 from H2 and O2 has been studied over zeolite beta-supported Pd and zeolite beta-adsorbed organic compounds such as 1,4-benzoquinone (BQ), hydroquinone (HQ), azobenzene (AB) and hydrazobenzene (HAB). According to catalytic results, zeolite beta-supported Pd catalysts display effective performance relative to those prepared from other types of zeolites reported and Pd-loaded zeolite beta-adsorbed HQ catalysts show enhanced activity compared to zeolite beta-supported Pd catalysts. In situ UV–Vis spectroscopic study indicates that HQ can readily be converted to BQ reversibly under H2 and air inside zeolite beta only in the presence of Pd. The results suggest that HQ acts as a strong hydrogen transfer agent to promote the production of H2O2 from H2 and O2 in cooperation with a Pd catalyst. By contrast, adsorption of BQ, AB and HAB induces suppression of the catalytic properties of Pd/zeolite beta. 相似文献
73.
When a target is enclosed by a 4-dot mask that persists after the target disappears, target identification is worse than it is when the mask terminates with the target. This masking effect is attributed to object substitution masking (OSM). Previewing the mask, however, attenuates OSM. This study investigated specific conditions under which mask preview was, or was not, effective in attenuating masking. In Experiment 1, the interstimulus interval (ISI) between previewed mask offset and target presentation was manipulated. The basic preview effect was replicated; neither ISI nor preview duration influenced target identification performance. In Experiment 2, mask configurations were manipulated. When the mask configuration at preview matched that at target presentation, the preview effect was replicated. New evidence of ineffective mask preview was found: When the two configurations did not match, performance declined. Yet, when the ISI between previewed mask offset and target presentation was removed such that the mask underwent apparent motion, preview was effective despite the configuration mismatch. An interpretation based on object representations provides an excellent account of these data. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
Young‐Jung Wee Lebaka Veeranjaneya Reddy Soon‐Do Yoon Hwa‐Won Ryu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(5):757-762
BACKGROUND: Purification and enzymatic properties of a chitosanase from Bacillus subtilis RKY3 have been investigated to produce a chitooligosaccharide. The enzyme reported was extracellular and constitutive, which was purified by two sequential steps including ammonium sulfate precipitation and ion exchange chromatography. RESULTS: Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of the purified chitosanase revealed one single band corresponding to a molecular weight of around 24 kDa. The highest chitosanase activity was found to be at pH 6.0 and at 60 °C. Although the mercaptide forming agents such as Hg2+ (10 mmol L?1) and p‐hydroxymercuribenzoic acid (1 mmol L?1, 10 mmol L?1) significantly or totally inhibited the enzyme activity, its activity was enhanced by the presence of 10 mmol L?1 Mn2+. The enzyme showed activity for hydrolysis of soluble chitosan and glycol chitosan, but colloidal chitin, carboxymethyl cellulose, crystalline cellulose, and soluble starch were not hydrolyzed. The analysis of chitosan hydrolysis by thin‐layer chromatography and viscosity variation revealed that the purified enzyme should be endosplitting‐type chitosanase. CONCLUSION: The chitosanase produced by Bacillus subtilis RKY3 was a novel chitosanlytic enzyme with relatively low molecular weight, which is a versatile enzyme for chitosan hydrolysis because it could hydrolyze soluble chitosan into a biofunctional oligosaccharide at a high level. Copyright © 2011 Society of Chemical Industry 相似文献
75.
The alkylation of benzene with 1-dodecene was studied over solid-acid zeolites, such as H-mordenite, H-USY, HY, and H-ZSM-5, in a batch reactor at 140°C and 10 atm. H-mordenite showed the highest selectivity of 78.2% for 2-phenyldodecane with 100% conversion. Depending on the catalyst amount (from 0.5 to 1.0 g) and the molar ratio of benzene to 1-dodecene (from 7 to 10), the conversion of 1-dodecene varied in the range from 63.8 to 100%. Furthermore, modification of H-mordenite by dealumination using nitric acid and by solid ion exchange with Mg2+ and Fe3+ ions led to the improvement of the selectivity for 2-phenyldodecane, and simultaneously reduction of the conversion of 1-dodecene is observed. In addition, it was found by pyridine adsorption FT-IR study that both strong Brønsted and Lewis acid sites are closely related to the conversion. 相似文献
76.
Piet Rietveld Bert Zwart Bert van Wee Toon van den Hoorn 《The Annals of Regional Science》1999,33(3):269-287
This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips
by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and
reported travel time. Reported travel times are usually rounded in multiples of five minutes. This calls for special statistical
techniques. Ignoring the phenomenon of rounding leads to biased estimation results for shorter distances. Rather surprisingly,
the distance as the crow flies and the network distance appear to be slightly better proxies of the reported travel time compared
with the shortest network travel time as indicated by the route planner. We conclude that where actual driving times are missing
in commuting research the other three indicators mentioned may be used as proxies, but that the following problems may emerge:
actual travel times may be considerably higher than network times generated by route planners, and the average speed of trips
increases considerably with distance, implying an overestimate of travel time for long distance commuters. The only personal
feature that contributes significantly to variations in reported travel times is gender: women appear to drive at lower average
speeds according to our data. As indicated in the paper this may be explained by the differences in the car types of male
and female drivers (females drive older and smaller cars) as well as higher numbers of stops/trip chaining among women. A
concise analysis is carried out for carpoolers. Car-pooling leads to an increase in travel time of some 17% compared with
solo drivers covering the same distance. In the case of car poolers, the above mentioned measures appear to be very poor proxies
for the actual commuting times.
Received: November 1996/Accepted: January 1998 相似文献
77.
78.
Choo Wee Sim Kharidah Muhammad Salmah Yusof Jamilah Bakar & Dzulkifly Mat Hashim 《International Journal of Food Science & Technology》2004,39(9):947-958
Response Surface Methodology (RSM) was used to establish the optimum time and temperature for production of acid‐hydrolysed winged bean protein (aHWBP) and acid‐hydrolysed soybean protein (aHSBP). Seven hours of hydrolysis at 125 °C was the optimum condition for producing aHWBP, whereas it was 5 h of hydrolysis at 125 °C for production of aHSBP. Although aHWBP and aHSBP produced using these conditions had favourable sensory qualities, they were found to have up to 25 mg kg?1 of 3‐monochloropropane‐1,2‐diol (3‐MCPD). This exceeds the maximum level permissible in Commission Regulation (EC) No 466/2001. However, additional alkaline thermal treatment at pH 8.5 for 2 h at 100 °C effectively reduced the 3‐MCPD contents of aHWBP and aHSBP to undetectable levels. aHWBP has a distinctive flavour, which is different from that of aHSBP. The former has higher mean scores for meaty and vegetable attributes but lower mean scores for soy, umami and beany attributes than the latter. 相似文献
79.
Organic light emitting devices performance improvement by inserting thin parylene layer 总被引:1,自引:0,他引:1
Lin Ke Ramadas Senthil Kumar Keran Zhang Soo Jin Chua A. T. S. Wee 《Synthetic Metals》2004,140(2-3):295-299
An organic light emitting device (OLED) structure with a thin parylene layer deposited by low-temperature chemical vapour deposition (CVD) at the anode–organic interface was fabricated. Such a structure gives off higher efficiency, a smaller number and smaller size dark non-emissive areas, slower growth rate of the dark areas and a longer device lifetime compared to one without the parylene layer. The parylene modified indium tin oxide (ITO) surface shows an increased work-function and a reduced surface roughness compared to that of the bare ITO surface. The interface optimisation contributes to the device performance improvement. 相似文献
80.