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111.
Anionic polymerizations of chiral N-phenylmaleimide derivatives bearing an oxazoline pendant (OPMI) were carried out with n-BuLi initiator to obtain optically active polymers. The polymer yields and specific optical rotations () were found to be significantly influenced by the reaction solvent, temperature, and the molar ratio of initiator to monomer. Particularly, the specific optical rotations exhibited a linear dependence on the molecular weights for the formed polymers, and the inversion from levo- to dextro-specific rotation was also observed with an increase in the molecular weights. On the basis of the results from circular dichroism (CD) and 13C NMR spectral analyses, the optical activity of poly(OPMI)s was attributed not only to the chirality of oxazolinyl groups in monomeric units but also to the partial helical structure due to an excess of threo-diisotactic configuration in the main chain. 相似文献
112.
Tang J Tang H Sun W Plancher H Radosz M Shen Y 《Chemical communications (Cambridge, England)》2005,(26):3325-3327
Novel sorbent and membrane materials for CO2 separation, poly(ionic liquid)s made from ionic liquid monomers, poly[p-vinylbenzyltrimethyl ammonium tetrafluoroborate](P[VBTMA][BF4]) and poly[2-(methacryloyloxy)ethyltrimethylamnonium tetrafluoroborate](P[MATMA][BF4]) have absorption capacities 7.6 and 6.0 times of those of room-temperature ionic liquids, e.g.[bmim][BF4], respectively, with reversible and fast sorption and desorption. 相似文献
113.
TANG Weilin 《声学学报:英文版》1993,(3)
In this paper the physical acoustic method or the Kirchhoff approxima-tion is extended to treat the scattering of a nonrigid surface in order to estimatethe target strength of targets with absorbing coatings.By using the locally planewave approximation,the relationship between the sound pressure and its normalderivative on the surface can be represented by the plane wave reflectioncoefficient and the acoustic impedance of the surface.The resulting modifiedKirchhoff approximation involves the plane wave reflection coefficient.For aimpedance sphere,a comparison between the physical acoustic method and theexact solution shows that the physical acoustic method still is a good approxima-tion at higher κα values. 相似文献
114.
115.
The authors describe a screen-printed and disposable electrode for the nonenzymatic determination of hydrogen peroxide (H2O2). It is based on the controllable synthesis and deposition of silver nanoparticles (AgNPs) of different sizes on a nanocomposite consisting of reduced graphene oxide and cerium (IV) oxide (rGO@CeO2) that was placed on a screen-printed electrode (SPE). X-ray powder diffractometry and Fourier transform infrared spectroscopy were used to characterize the composition of the hybrid nanomaterials. Electrochemical impedance spectroscopy and scanning electron microscopy were employed to study the interfacial properties and morphologies of different electrodes. The sensor was investigated by cyclic voltammetry and chronoamperometry (i-t plots). After optimization, the modified SPE showed a good performance towards the electrocatalytic reduction of H2O2, best at a working potential of ?0.3 V (vs. Ag/AgCl). Features of merit include a broad linear analytical range extending from 0.5 μM to 12 mM, and a limit of detection as low as 0.21 μM (at an S/N ratio of 3). The sensor is simple, quick, stable and reliable. It was applied to the determination of H2O2 in (spiked) contact lens care solutions with good accuracy and recovery. 相似文献
116.
A new polytungstoarsenate-based 3d-4f heterometallic aggregate has been synthesized, consisting of three {alpha-AsW10 O 38} fragments bridged by three {Fe-(mu3-O)3-Ce} heterometallic clusters. 相似文献
117.
118.
An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed capable of simultaneously
measuring chlortetracycline (CTC), epi-chlortetracycline, and isochlortetracycline (ICTC), as well as other structurally related
tetracyclines in swine manure. A simple sample preparation was used consisting of extraction, dilution, centrifugation, and
ultrafiltration. The concentrations of analyte were calculated using d6-tetracycline as an internal standard in the matrix-matched standard curve. A solvent gradient resolved the compounds in 3.5 min
with an additional 1.5 min of re-equilibration allowing the analyses of a large number of samples in a short period of time.
MS/MS was used as the detection method giving analyte confirmation in addition to a large dynamic range and low detection
limit. The UHPLC-MS/MS method successfully resolved multiple degradation products of CTC from the complex manure matrix. The
method detection limits ranged from 1.9 pg/μL for CTC to 7.3 pg/μL for ICTC, and the calibration curve was linear from 1 to
10,000 pg/μL. The method was tested by measuring CTC and its degradation products as a function of time in incurred swine
manure that had been incubated at three different temperatures (22 °C, 38 °C, and 55 °C). CTC concentration at 22 °C decreased
44% after 25 days; greater percentage decreases were observed when the manure was stored at elevated temperatures (96% and
98% for 38 °C and 55 °C, respectively). The concentration of the microbiologically inactivate isomer, ICTC, increased over
the incubation period. At 22 °C, ICTC continued to increase through 25 days of incubation; at 38 °C, ICTC concentration plateaued
on day 14 while at 55 °C ICTC concentration plateaued on day 7, with concentration increases of 198%, 374%, and 282% for 22 °C,
38 °C, and 55 °C, respectively. 相似文献
119.
基于色氨酸本征荧光测量的生物气溶胶检测技术研究 总被引:1,自引:0,他引:1
生物气溶胶与环境质量和人类健康密切相关。基于光学测量的气溶胶检测技术具有快速、无损和灵敏的优点,是目前的研究主流。而对检测系统的标定技术及其评价方法尚无国家标准可依。基于本征荧光测量技术,研制完成了一套针对包括病毒气溶胶在内的生物气溶胶检测装置。并在此基础上,以色氨酸气溶胶作为被检物,提出了一种生物气溶胶检测与标定方法。实验结果表明,研制的检测装置对色氨酸气溶胶具良好的线性响应特性,线性相关系数R2≥0.99,灵敏度达到4000L-1。证明了通过测量气溶胶中色氨酸含量检测生物气溶胶技术的可行性与可靠性。还探讨了利用多通道本征荧光检测技术实现对生物粒子种类进行预判别的可行性。 相似文献
120.
A 4×4 reconfigurable mesh-based inter-chip optical interconnection network is reported for distributed-memory multiprocessor system and the experiment confirmed that the data rate in each channel could reach above 3.125 Gbps, which would be a good solution to solve the communication bottlenecks between processors. Each node of this reconfigurable mesh could realize 15 internal connection patterns to complete the interconnections of processors. Besides, this mesh interconnect network via ultra-high bandwidth waveguides embedded in EOPCB can realize flexible multiprocessor system architecture options. 相似文献