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排序方式: 共有2410条查询结果,搜索用时 234 毫秒
191.
Licheng Tan Yiwang Chen Weihua Zhou Huarong Nie Xiaohui He 《Polymer Degradation and Stability》2010,95(9):1920-149
A series of aliphatic biodegradable poly(butylene succinate-co-dl-lactide) (PBSLA) copolyesters were synthesized with the aim of improving the degradation rate of poly(butylene succinate) (PBS) by incorporation of dl-oligo(lactic acid) (OLA) into the PBS molecular chains. The composition and sequential structure of the aliphatic copolyesters were investigated by proton nuclear magnetic resonance (1H NMR) spectroscopy. The crystallization behaviors, the crystal structure and morphology of the copolyesters were investigated by using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM), respectively. The results indicate that the crystallization of the copolyesters was restricted by the incorporation of lactide (LA) units, which further tuned the mechanical properties of the copolyesters. The copolyesters could form complete spherulites and exhibit the same crystal structure as that of PBS. Enzymatic study indicated that the copolyesters with higher content of LA units degraded faster, and the degradation began in the amorphous regions and then in the crystalline regions. The morphology and the resulting degradation products of the copolyesters were investigated by scanning electron microscopy (SEM) and 1H NMR analysis during the degradation process. 相似文献
192.
In this paper, we report a facile solvothermal route capable of aligning MnOOH nanocrystals on graphene. X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations indicate that the exfoliated graphene sheets are decorated randomly by MnOOH nanocrystals, forming well-dispersed graphene-MnOOH nanocomposites. Dissolution-crystallization and oriented attachment are speculated to be the vital mechanisms in the synthetic process. The attachment of additives, such as MnOOH nanoparticles, are found to be beneficial for the exfoliation of GO as well as preventing the restack of graphene sheets. Moreover, cyclic voltammetry (CV) analyses suggest that the electrochemical reversibility is improved by anchoring MnOOH on graphene. Notably, the as-fabricated nanocomposites reveal unusual catalytic performance for the thermal decomposition of ammonium perchlorate (AP) due to the concerted effects of graphene and MnOOH. This template-free method is easy to reproduce, and the process proceeds at a low temperature and can be readily extended to prepare other graphene-based nanocomposites. 相似文献
193.
Yong Xue HuaLi Nie Limin Zhu Shubai Li Haitao Zhang 《Applied biochemistry and biotechnology》2010,160(1):109-121
Papain (EC 3.4.22.2) has been chemically modified using two novel reagents including different anhydrides of 1,2,4-benzenetricarboxylic
and pyromellitic acids. Then, the modified papain was immobilized on the activated cotton fabric by a two-step method. The
number of free amino groups in the modified protein was investigated through the 2,4,6-trinitrobenzenesulfonic acid method.
Energy dispersive spectrometer was used to characterize papain immobilization. Some parameters of both modified and native
papain immobilized on cotton fabric, such as optimum temperature, optimum pH, and the stabilities for reservation in various
detergents were studied and compared. The resultant papain had its optimum pH shifted from 6.0 to 9.0. Compared with immobilized
native papain, the thermal stability and the resistance to alkali and washing detergent of immobilized modified enzyme were
improved considerably. When the concentration of detergent was 20 mg/ml, the activity of the immobilized pyromellitic papain
retained about 40% of its original activity, whereas the native papain was almost inhibited. This work demonstrated that the
cotton fabric immobilized modified papain has potential applications in the functional textiles field. 相似文献
194.
Daiwon Choi Donghai Wang Vish V. Viswanathan In-Tae Bae Wei Wang Zimin Nie Ji-Guang Zhang Gordon L. Graff Jun Liu Zhenguo Yang Tien Duong 《Electrochemistry communications》2010,12(3):378-381
Li-ion batteries made from LiFePO4 cathode and anatase TiO2/graphene composite anode were investigated for potential application in stationary energy storage. Fine-structured LiFePO4 was synthesized by a novel molten surfactant approach whereas anatase TiO2/graphene nanocomposite was prepared via self-assembly method. The full cell that operated at 1.6 V demonstrated negligible fade even after more than 700 cycles at measured 1 C rate. While with relative lower energy density than traditional Li-ion chemistries interested for vehicle applications, the Li-ion batteries based on LiFePO4/TiO2 combination potentially offers long life and low cost, along with safety, all which are critical to the stationary applications. 相似文献
195.
Integration of paper-based microfluidic devices with commercial electrochemical readers 总被引:2,自引:0,他引:2
The combination of simple Electrochemical Micro-Paper-based Analytical Devices (EμPADs) with commercially available glucometers allows rapid, quantitative electrochemical analysis of a number of compounds relevant to human health (e.g., glucose, cholesterol, lactate, and alcohol) in blood or urine. 相似文献
196.
Yang Y Nie W Yuan J Zhang B Wang Z Wu Z Guo Y 《Experimental & molecular medicine》2010,42(11):768-776
Deregulation of endothelial nitric oxide synthase (eNOS) plays an important role in the development of multiple cardiovascular diseases. Our recent study demonstrated that genistein supplementation attenuates pulmonary arterial hypertension in broilers by restoration of endothelial function. In this study, we investigated the molecular mechanism by using broiler pulmonary arterial endothelial cells (PAECs). Our results showed that genistein stimulated a rapid phosphorylation of eNOS at Ser(1179) which was associated with activation of eNOS/NO axis. Further study indicated that the activation of eNOS was not mediated through estrogen receptors or tyrosine kinase inhibition, but via a phosphatidylinositol 3-kinase (PI3K)/Akt-dependent signaling pathway, as the eNOS activity and related NO release were largely abolished by pharmacological inhibitors of PI3K or Akt. Thus, our findings revealed a critical function of Akt in mediating genistein-stimulated eNOS activity in PAECs, partially accounting for the beneficial effects of genistein on the development of cardiovascular diseases observed in animal models. 相似文献
197.
One novel type of Y-shaped amphiphilic copolymers with two hydrophobic poly(solketal acrylate) (PSA) branches and one hydrophilic monomethoxy poly(ethylene glycol) (MPEG) block was synthesized by atom transfer radical polymerization (ATRP). These Y-shaped polymers can disperse in aqueous media to self-assemble into micellar aggregates with a spherical core-shell structure. The aqueous copolymer solutions exhibited transmittancy transition in the temperature range of 30-60 °C via optical transmittance measurements. An interesting thermo-dependent size of the micellar aggregates was observed by dynamic light scattering techniques and transmission electron microscopy, which showed that the micelle diameters were decreased with temperature increasing. The nile red release from the micelles at 25 °C and 37 °C under various pHs showed that temperature has great influence on release behavior. With good biocompatibility, the micellar aggregates formed from MPEG-block-(PSA)(2) may serve as one promising thermosensitive nanovehicle for targeted drug delivery. 相似文献
198.
199.
Interaction of two identical excitable spiral waves in a bilayer system is studied. We find that the two spiral waves can be completely synchronized if the coupling strength is sufficiently large. Prior to the complete synchronization, we find a new type of weak synchronization between the two coupled systems, i.e., the spiral wave of the driven system has the same geometric shape as the spiral wave of the driving system but with a much lower amplitude. This general behavior, called projective synchronization of two spiral waves, is similar to projective synchronization of two coupled nonlinear oscillators, which has been extensively studied before. The underlying mechanism is uncovered by the study of pulse collision in one-dimensional systems. 相似文献
200.
Yi-you Nie Ming-huang Sang Yuan-hua Li Jun-chang Liu 《International Journal of Theoretical Physics》2011,50(5):1367-1371
We propose a scheme for splitting an arbitrary two-qubit state among three parties by using a six-qubit cluster-class state
as a quantum channel. Based on two Bell-state measurements (BSMs) and a two-qubit projective measurement, any one of the two
agents can reconstruct the original state if he/she collaborates with the other one, whilst individual agent obtains no information. 相似文献