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71.
72.
The complexes of poly(methacrylic acid-co-methyl methacrylate) network with poly(ethylene glycol) stabilized byhydrogen bonds were prepared. By introducing the poly(ethylene glycol), a large difference in storage modulus below andabove the glass transition temperature occurred and the complexes exhibited shape memory behaviors. The morphology ofcomplexes was studied by using DSC, WAXD, and DMA. The results indicate that the fixed phase of this kind of novelshape memory materials is the network, and the reversible phase is the amorphous state of PEG:PMAA complex phase. Theshape recoverability almost reaches 100%. This type of complexes can be regarded as a novel shape memory network. 相似文献
73.
A high-powered, microwave-induced nitrogen–oxygen plasma (N2–O2–MIP) generated by using an Okamoto cavity at atmospheric pressure was investigated when the observation height, the flow rate of carrier gas, and the oxygen content were varied as the experimental parameters. The emission characteristics of the plasma were evaluated with regard to the excitation temperature and the intensity ratio of atomic line to ionic line. The excitation temperature of the N2–O2–MIP was in the range of 5100–5700 K when the oxygen content was varied from 0 to 30% at the observation height of 7 mm and the carrier gas flow rate of 0.6 l/min. The intensity ratio of atomic line to ionic line was elevated with an increase in the oxygen content. 相似文献
74.
The infrared spectra of phosphinic acid R2POOH dimers (R=CH3, CH2Cl, C6H5) have been studied in CCl4 and CH2Cl2 solutions (T=300 K). The infrared spectra of deuterated R2POOD dimers (R=CH3, CH2Cl) were also studied in the gas phase (T=400–550 K) and solid state (T=100–300 K). They are compared with previously studied spectra of the light (non-deuterated) dimers in the gas phase, in the solid state and in low-temperature argon matrices (T=12–30 K) in the 4000–400 cm−1 spectral region. It is found that the strong and broad ν(OH) dimer bands have similar shapes, nearly equal values of bandwidth and low-frequency shift, and possess the Hadzi ABC structure irrespective of the type of acid, significant differences of dimerization enthalpies, influence of solvent, the type of H-bonded complexes (cyclic dimers in the gas phase, in solutions, and in inert matrices, and infinite chains in the solid state), and temperature in the range 12–600 K. Isotopic ratio of the first moments of light and deuterated acid bands has been measured. Analysis of the ν(OH/OD) band of hydrogen bonded dimers of phosphinic acids shows that the interaction between the two intermolecular bonds O–HOP in a cyclic complex plays virtually no role in the mechanism of the ν(OH/OD) band formation; the shape of ν(OH/OD) band is controlled mainly by the POOH(D)O fragment; and the band shape of strong hydrogen bonded complexes is formed by a number of vibrational transitions from the ground state to different combination levels in the region 3500–1500 cm−1. 相似文献
75.
《Arabian Journal of Chemistry》2022,15(7):103933
In this study, a fingerprint-activity relationship modeling between chemical fingerprints and antirheumatic activity was established, and multivariate statistical analysis was used to evaluate the quality of Taxilli Herba (TH) from different hosts. Characteristic fingerprints of 20 batches of TH samples were generated by high-performance liquid chromatography coupled with triple quadrupole-time of flight tandem mass spectrometry (HPLC-Triple TOF-MS/MS), and the similarity analysis was calculated based on thirteen common characteristic peaks by hierarchical clustering analysis (HCA). Subsequently, nine efficacy markers were discovered by combining fingerprints and antirheumatic activity through grey correlation analysis (GCA) and bivariate correlation analysis (BCA). Meanwhile, the content of 5 constituents in 9 markers was determined by high-performance liquid chromatography coupled with triple quadrupole-linear ion trap tandem mass spectrometry (HPLC-QTRAP-MS/MS). The comprehensive quality of TH was assessed using multivariate statistical analysis, including principal components analysis (PCA) and technique for order preference by similarity to ideal solution (TOPSIS). The results showed that a high dose of TH extract could markedly ameliorate arthritis damage compared to other doses, with flavonoids playing an important role in the antirheumatic activity. The comprehensive quality of samples from Morus alba L. (SS) was superior to those from Liquidambar formosana Hance (FXS). The present study will demonstrate the markers associated with efficacy, and provide an applicable strategy for more comprehensive quality control and evaluation of TH. 相似文献
76.
Chu-In Charles Lee 《Annals of the Institute of Statistical Mathematics》1992,44(1):107-120
The Laplace continued fraction is derived through a power series. It provides both upper bounds and lower bounds of the normal tail probability % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaiqbfA6agzaaraaaaa!3DC0!\[\bar \Phi\](x), it is simple, it converges for x>0, and it is by far the best approximation for x3. The Laplace continued fraction is rederived as an extreme case of admissible bounds of the Mills' ratio, % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaaiqbfA6agzaaraaaaa!3DC0!\[\bar \Phi\](x)/(x), in the family of ratios of two polynomials subject to a monotone decreasing absolute error. However, it is not optimal at any finite x. Convergence at the origin and local optimality of a subclass of admissible bounds are investigated. A modified continued fraction is proposed. It is the sharpest tail bound of the Mills' ratio, it has a satisfactory convergence rate for x1 and it is recommended for the entire range of x if a maximum absolute error of 10-4 is required.The efforts of the author were supported by the NSERC of Canada. 相似文献
77.
This work describes the use of a dual-standard analysis approach termed the time-average ratio (TAR) in affinity capillary electrophoresis (ACE) to estimate binding constants of receptors to ligands. In this form of analysis the TAR is the migration time of the receptor divided by the average of the sum of the migration times of two non-interacting standards. This change in TAR as a function of the concentration of ligand yields a value for the binding constant. This concept is demonstrated using three model systems: carbonic anhydrase B (CAB, EC 4.2.1.1) and arylsulfonamides, vancomycin (Van) and ristocetin (Rist) from Streptomyces orientalis and Nocardia lurida, respectively, and d-Ala- d-Ala terminus peptides. Three ACE techniques are used to examine the three systems: standard ACE, flow-through partial-filling ACE (FTPFACE), and on-column derivatization coupled to ACE. The findings described here demonstrate that ACE data analyzed using the TAR form of analysis yield binding constants between receptors and ligands comparable to those estimated using other ACE forms of analysis. A comparison to three other forms of analysis is described. 相似文献
78.
《Arabian Journal of Chemistry》2020,13(2):4082-4091
In present study, an investigation was carried out to develop and validate an analytical method for the selective extraction and determination of griseofulvin (GSF) from plasma samples. For this purpose, a rational approach was made to synthesize and characterize the surface molecularly imprinted polymers (SMIPs). The SMIPs were utilized as solid phase extraction (SPE) sorbents. The SMIPs were prepared by using GSF as template molecule on the surface of modified silica particles through a non-covalent technique. The particles demonstrated high adsorption capacity (119.1 µg/mL), fast adsorption equilibrium time (30 min) and good recognition selectivity for the template drug. The scanning electron microscopy and infrared spectroscopy were used to explain the structural and morphological characteristics of the SMIPs and surface non-imprinted polymers. The SPE method was combined with HPLC for plasma analysis. The method validation results demonstrated that the established method possessed good linearity for GSF ranging from 0.1 to 50 µg/mL (R2 = 0.997). The limit of detection for this method was 0.02 µg/mL for rat plasma samples. The recoveries of GSF from spiked plasma samples were (90.7–97.7%) and relative standard deviations were (0.9–4.5%). Moreover, the SMIPs as selective SPE sorbent can be reused more than 8 times which is a clear advantage over commercial SPE sorbents. Finally, the usefulness of the proposed strategy was assessed by extraction and detection of GSF in real rat plasma samples. 相似文献
79.
利用双光束电子散斑干涉法(ESPI)对试件受热变形进行了实时观测,针对一次实验过程中得到的图片较多(300~500幅)的特点,在图像处理时摒弃了以往的手动识别等位移线的办法,用MATLAB语言编写了批处理程序,能够在采集的大量散斑图片中自动快速准确地标定等位移线,得到相应的位移和应变,并结合实时测量的温度值,获得了45钢和LY12铝合金在不同温升率下的热膨胀系数及其随温度的变化。实验结果表明,在涉及的温升率范围内,温升率的改变对材料热膨胀系数的影响不明显,材料的热膨胀系数随温度的升高略有上升。 相似文献
80.