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911.
912.
Absorbent hydrolyzed starch-g-PAN (HSPAN)/polyvinylalcohol (PVA) blend films crosslinked with epichlorohydrin (ECH) were prepared to overcome the phase separation and improve the mechanical properties of blend films. The absorbency of HSPAN/PVA blend films decreased with PVA contents due to the reduction of HSPAN contents which is known to play a major role in absorbing ability of the film. And also the absorbency decreased with the ECH contents due to the crosslinking reaction. As far as the solubility is concerned, it increased with PVA contents which is water soluble. But because of the crosslinking reaction between HSPAN and PVA by ECH, the solubility decreased with ECH contents. In the mechanical properties, the strength as well as the strain at break of the HSPAN/PVA blend films were improved very much if compared with HSPAN film, and those mechanical properties were improved even more by the reaction with ECH. The DSC thermograms of HSPAN films showed two major endothermic peaks at 32 and 128 °C, while those of PVA film showed two major endothermic peaks at 49 and 190 °C. In the non-crosslinked blend films, each four endothermic peak was apparent. But as the ECH content increased, both peaks at 128 and 190 °C disappeared and a new peak appeared at the intermediate temperature. In other words, the compatibility of blend films was increased by the reaction with ECH. Also, from the results of TGA, it was confirmed that the thermal degradation of blend films was decelerated by the crosslinking reaction.  相似文献   
913.
Recently, a new set of fundamental stereological formulae based on isotropically oriented probes through fixed points have been derived, the so-called nucleator estimation principle (cf. Jensen and Gundersen (1989, J. Microsc., 153, 249–267)). In the present paper, it is shown how a model-based version of these formulae leads to stereological estimators of reduced moment measures of stationary and isotropic random sets in n .  相似文献   
914.
915.
Poly{2,6‐bis(3‐dodecylthiophen‐2‐yl) benzo[1,2‐b;4,5‐b′]dithiophene} (PTBT) was synthesized, via oxidative polymerization by oxidative agent (FeCl3). The mole ratio of FeCl3 and monomer (3.5:1), and keeping low temperature during the dropping of diluted catalyst were very important for the polymerization without crosslinking. The PTBT was confirmed by 1H NMR, FTIR spectra, and elemental analysis. The PTBT has very good solubility in organic solvents such as chloroform, tetrahydrofuran, etc, and good thermal stability with Tg of 164 °C. The PTBT shows UV‐optical absorption at 406 nm and photoluminescence (PL) spectroscopy at 504 nm in a film. The highest occupied molecular orbital (HOMO) energy of the polymer is ?5.71 eV by measuring cyclic voltammetry (CV). A solution‐processed polymer thin film transistor device shows a mobility of 3 × 10?5 – 8 × 10?5 cm2 V?1 s?1, and an on/off current ratio of 104. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5277–5284, 2007  相似文献   
916.
Summary. Stochastic Automata Networks (SANs) are widely used in modeling communication systems, manufacturing systems and computer systems. The SAN approach gives a more compact and efficient representation of the network when compared to the stochastic Petri nets approach. To find the steady state distribution of SANs, it requires solutions of linear systems involving the generator matrices of the SANs. Very often, direct methods such as the LU decomposition are inefficient because of the huge size of the generator matrices. An efficient algorithm should make use of the structure of the matrices. Iterative methods such as the conjugate gradient methods are possible choices. However, their convergence rates are slow in general and preconditioning is required. We note that the MILU and MINV based preconditioners are not appropriate because of their expensive construction cost. In this paper, we consider preconditioners obtained by circulant approximations of SANs. They have low construction cost and can be inverted efficiently. We prove that if only one of the automata is large in size compared to the others, then the preconditioned system of the normal equations will converge very fast. Numerical results for three different SANs solved by CGS are given to illustrate the fast convergence of our method. Received March 17, 1998 / Revised version received August 16, 1999 / Published online July 12, 2000  相似文献   
917.
First, we prove the decomposition theorem for the regularities of multifractal Hausdorff measure and packing measure in ” d . This decomposition theorem enables us to split a set into regular and irregular parts, so that we can analyze each separately, and recombine them without affecting density properties. Next, we give some properties related to multifractal Hausdorff and packing densities. Finally, we extend the density theorem in [6] to any measurable set.  相似文献   
918.
Two new diterpene derivatives named cinnacasol ( 1 ) and cinnacaside ( 2 ) were isolated from the MeOH extract of the twigs of Cinnamomum cassia Blume . Their structures were identified based on physicochemical properties and spectroscopic‐data analyses such as IR, HR‐MS, and 1D‐ and 2D‐NMR, and by comparison with published values.  相似文献   
919.
920.
We develop a quantum key distribution (QKD) system with fast active optical path length compensation. A rapid and reliable active optical path length compensation scheme is proposed and applied to a plug-and-play QKD system. The system monitors changes in key rates and controls it is own operation automatically. The system achieves its optimal performance within three seconds of operation, which includes a sifted key rate of 5.5 kbps and a quantum bit error rate of less than 2% after an abrupt temperature variation along the 25 km quantum channel. The system also operates well over a 24 h period while completing more than 60 active optical path length compensations.  相似文献   
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