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991.
Silver nanowires have attracted considerable attention in the past decade, due to their unique physical and chemical properties,
which can lead to a wide variety of potential applications. In this work, silver nanowires have been fabricated using an alcohol
ionic liquid by a one-step method in the absence of any extra capping agents. The method is based on the reduction of AgNO3 by 1-(3-hydroxylpropyl)-3-methylimidazolium tetrafluoroborate (C3OHmimBF4) in an aqueous solution at 180°C for 18 h. The products were characterized by a scanning electron microscope (SEM), transmission
electron microscope (TEM), energy-dispersive X-ray spectrograph (EDS), and powder X-ray diffractometry (XRD). The experimental
results indicate that both reaction temperature and special properties of C3OHmimBF4 play important roles in the formation of silver nanowires. 相似文献
992.
Shenghua Liang Wenzhou LiTong Gao Xiangying ZhuGuimei Yang Daming Ren 《Journal of Bioscience and Bioengineering》2010,110(2):165-168
Genes encoding purine nucleoside phosphorylase (deo D), uridine phosphorylase (udp) and thimidine phosphorylase (deo A) from Escherichia coli BL21 were cloned and overexpressed in E. coli DH5α. The recombinant strains were employed to synthesize 2′-deoxyadenosine (dAR) and 6-methylpurine-2′-deoxyriboside (MePdR). Experimental parameters such as strains, temperature, pH, reagent concentration and cell mass were optimized. Under the optimal situation, 96% adenine was converted to dAR and 95% 6-methylpurine (MeP) was converted to MePdR in an hour, using 0.2‰ (dry wt./v) cell paste as biocatalyst. 相似文献
993.
简述了剩余焦炉煤气综合利用的途径,分析了在不同结焦时间下的合成气量分配情况,针对由于结焦时间较长低负荷工况下出现合成气量不足的情况提出了解决措施,根据提出的解决措施制定了设想工艺方案,采用UGI炉气化技术工艺造气来解决合成气不足的问题较为现实,整体工艺方案的预计投资约1000万元。 相似文献
994.
Five Holstein lactating dairy cows fed 5 total mixed rations (TMR) with different forage combinations were used in a 5 × 5 Latin square design to investigate diurnal variations of progesterone (P4), testosterone, and androsta-1,4-diene-3,17-dione (ADD) concentrations in the rumen. Meanwhile, different P4 inclusion levels [0 (control), 2, 20, 40, 80, and 100 ng/mL in culture fluids] were incubated in vitro for 6, 12, 24, 36, 48, and 72 h together with rumen mixed microorganisms grown on a maize-rich feed mixture (maize meal:Chinese ryegrass hay = :1) with an aim to determine microbial P4 transformation into testosterone and ADD. Ruminal P4, testosterone, and ADD concentrations of lactating dairy cows were greater in the TMR with forage combination of corn silage plus alfalfa hay or Chinese wild ryegrass hay than the TMR with the corn stover-based forage combination. The diurnal fluctuation pattern showed that P4, testosterone, and ADD concentrations in the rumen were greater at nighttime than daytime and peaked 6 h after feeding in the morning or afternoon. The in vitro batch cultures showed that the P4 elimination rate was highest at the P4 addition of 20 ng/mL and declined with the further increased addition of P4. The treatments after dosing P4 exhibited a shorter time than the control group until half of the initial P4 inclusion was eliminated (i.e., half time), and the lowest half time (1.46 h) occurred at the P4 addition of 20 ng/mL. In summary, the ruminal steroids concentration was affected by forage type and quality, and the rumen microorganisms exhibited great ability to transform P4 into testosterone and ADD, depending on incubation time and initial P4 addition level, suggesting that the host might affect the metabolism of its rumen microorganisms via the endogenous steroids. 相似文献
995.
In the present study, creep properties of as-cast Mg-5Al-5Ca-2Sn(AXT552) alloy were investigated by means of a GWT304 creep testing machine at temperatures of 175 °C and 200 °C in the stress range of 35-90 MPa. Results show that creep rates increase with applied stress at an identical temperature. Creep strain at 100 hours is 0.0518% and 0.083% at creep conditions of 175°C/75 MPa and 200°C/60 MPa, respectively, which is comparable to MRI230 D and much lower than most of AX series alloys. By the observation and analysis for samples before and after creep tests using a Shimadzu XRD-7000 type X-ray diffractometer(XRD) and a Hitachi S-3400 N type scanning electron microscope(SEM), it was found that Al_2Ca(C15) phase precipitated out of C36 phase or matrix. The cavity formation and connection at the interface of soft matrix and hard intermetallics caused the propagation of cracking along the eutectic phase during creep process and dislocation accommodated grain/phase boundary sliding is expected to be the dominant creep mechanism. 相似文献
996.
Yu He Zhiwei Hu Mengda Ren Changkun Ding Peng Chen Qun Gu Qiong Wu 《Journal of materials science. Materials in medicine》2014,25(2):561-571
Two types of fibers were prepared by using bio-based materials: a mono-filament made from poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and a multi-filament made from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polylactic acid (PLA) blend. The two fibers were evaluated for mechanical properties, biocompatibility and degradability for the potential application as medical sutures. The PHBHHx fiber showed remarkable biocompatibility by H.E. Stainning, with very little impact to the surrounding tissues. The degradation of the fiber was observed by SEM after implantation for 36 weeks, and the major degradation product was detected after 96 weeks. Consistently, the PHBHHx fiber maintained more than half of the mechanical properties after 96 weeks. The other fiber was prepared by twisting PHBV/PLA blend strands to a bunch, and showed high biocompatibility and relatively high degradability. The bunched structure loosed after 36 weeks of implantation. These low-cost and easily prepared fibers have great potential in medical applications, since they could avoid the formation of fibrous capsule, reduce the size of scar, and degrade into non-toxic and even beneficial products. 相似文献
997.
介绍了轮胎-地面接触模型的研究现状、研究手段及方法。指出了该领域发展存在的问题,提出有限元方法是轮胎-地面接触模型今后研究的重要方向。 相似文献
998.
999.
Lihua Ran Curtis Dyreson Anneliese Andrews Renée Bryce Christopher Mallery 《Information and Software Technology》2009,51(2):460-477
Many organizations rely on web applications that use back-end databases to store important data. Testing such applications requires significant effort. Manual testing alone is often impractical, so testers also rely on automated testing techniques. However, current automated testing techniques may produce false positives (or false negatives) even in a perfectly working system because the outcome of a test case depends on the state of the database which changes over time as data is inserted and deleted. The Automatic Database Tester (AutoDBT) generates functional test cases that account for database updates. AutoDBT takes as input a model of the application and a set of testing criteria. The model consists of a state transition diagram that shows how users navigate pages, a data specification that captures how data flows, and an update specification that shows how the database is updated. AutoDBT generates guard queries to determine whether the database is in a state conducive to performing and evaluating tests. AutoDBT also generates partial oracles to help validate whether a back-end database is updated correctly during testing. This paper describes the design of AutoDBT, a prototype implementation, several experiments with the prototype, and four case studies. 相似文献
1000.