Conformational analysis of 2,2 '-bithiophene under interaction of external electric field defined by point charges

Conformational analysis of 2,2'-bithiophene (BT) under the influence of an electric field (EF) constructed by point charges has been performed by using semi-empirical Austin Model 1 (AM1) and Parametric model number 3 (PM3) calculations. When the EF perpendicular to the molecular conjugation chain is applied, both AM1 and PM3 calculations show an energy increase of the anti-conformation. AM1 predicts that the global minimum shifts to syn-conformation when the EF strength is larger than a critical value. and PM predicts that the local minimum in anti-conformation vanishes. This kind of EF effect has been ascribed to the EF and dipole moment interaction.

新型侧链液晶M5MPP/MMEANB高聚物的合成与表征

以 4,4’ 二羟基联苯、4 硝基苯胺、二溴己烷、甲基丙烯酸、氯代乙醇为原料合成了单体甲基丙烯酸[5 (4’ 甲氧基联苯 4 氧基 )戊基 ]酯 (M 5MPP)、4 硝基偶氮苯基甲基 2 甲基丙烯酸酯基乙胺 (MMEANB) ,并完成了单体的聚合和共聚 ,得到了含有非线性光学活性基团 (NLO)的侧链液晶高分子 ,对其结构进行了表征 .结果表明 ,均聚物PM 5MPP及共聚物 (M 5MPP/MMEANB)属双向液晶高分子 ;PMMEANB属于非晶性高分子 .证实了分子间吸电子与给电子基团相互作用有利于提高液晶高分子热稳定性 ,共聚物 (M 5MPP/MMEANB)具有较宽的液晶相温度范围 .

官能化聚烯烃弹性体增韧PA1010体系Ⅱ.结晶行为的研究

用 WAXD、偏光显微镜 (PM)及 DSC研究了聚烯烃弹性体乙烯 - α-烯烃共聚物 (EOCP)对 PA10 10结晶行为的影响。WAXD结果显示纯弹性体 (EOCP)和接枝弹性体 (EOCP- g- MA)对 PA10 10的晶型均不产生影响。PM���察则表明共混体系中 EOCP与 PA10 10的相互作用很弱 ,在 PA10 10结晶过程中 ,大部分 EOCP被排除在球晶之外 ;而接枝 EOCP与 PA10 10存在较强的相互作用 ,大量的 EOCP- g- MA作为成核剂 ,使 PA10 10球晶向细晶化方向发展 ,而且随弹性体含量的增多而加强。DSC分析证实了接枝EOCP以异相成核剂的方式促进了 PA10 10的结晶 ,尤其是促进了 PA10 10的高温结晶

THE DEHYDRATION BEHAVIOR OF RARE-EARTH COMPLEXES OF M-NITROBENZOIC ACID

Rare earth complexes of m-nitrobenzoic acid (LnL3.2H2O, Ln = La-Lu and Y, except Pm, HL = m-nitrobenzoic acid) were synthesized and characterized by elemental analysis, chemical analysis, IR spectroscopy and X-ray diffraction analysis. The dehydration beh

稀土与二(2,4,4-三甲基戊基)膦酸固体配合物的研究

合成了除Pm���外的16个稀土与二(2,4,4-三甲基戊基)膦酸(HBTMPP)的固体配合物,其组成为RE(BTMPP)_3,对配合物的性质进行了表征,热分析表明,在氩气中,热分解是一步完成的,在空气中,热分解分二步完成,前者的热分解产物是RE_4 (P_2O_7)_3,后者的产物为RE_2P_4O_(13)测定了配合物的振动光谱,对其主要吸收谱带进行了归属,配合物中RE-O键具有较高的离子特性

KALMAN FILTERING FOR RESOLUTION OF OVERLAPPING LINES IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

A Kalman filter was developed for resolving overlapping lines in inductively coupled plasma atomic emission spectrometry (ICP-AES) and evaluated experimentally with the determination of La in the presence of Ho, and Cu in the presence of Pr. The whiteness of the innovation sequence for an optimal filter was explored to be the criterion for the correction of the wavelength positioning errors which may occur in spectral scans. Under the conditions of the medium-resolution spectrometer and 1.5 pm step size in scans, the filter effectively resolved the Cu/Pr line pair having a small peak separation of 4.8 pm. For the La/Ho line pair with a peak distance of 9.8 pm, an unbiased estimate for La concentration was still obtained even when the signal-to-background ratio was down to 0.048. Favourable detection limits for real samples were achieved. Unstructured backgrounds were modeled theoretically and all spectral scans therefore did not require the correction for solvent.

稀土与L-苯丙氨酸配合物的pH电位法及量热滴定法研究

本文在25℃和0.15mol·dm~(-3)(NaCl)离子强度下,用pH电位法和量热滴定法测定了十五个稀土元素(Y和除Pm���的镧系元素)与L-苯丙氨酸1∶1配合物的稳定常数及热力学函数。L-苯丙氨酸通过—CO_2~-和—NH_2与稀土离子配位,生成较稳定的1∶1配合物。配合物稳定性呈“四分组效应”。配合物稳定性顺序中Y的位置向轻稀土方向移动。体系的熵变是配位反应驱动力。离子的去水化在配位反应中超重要作用。

稀土乙酸盐水合物热分解机理的研究

采用TG—DTG和DSC法,在空气气氛下对14种稀土乙酸盐水合物(Ln(Ac)_3·nH_2O,Ln=La～Lu+Y,除Ce、Pm,n=4或5]的热分解机理进行研究。热分解机理在钕、钆处发生转折。无水盐的形成温度随原子序数的增加而降低。采用Freemen-Carroll和Kissinger法计算了稀土乙酸盐脱水、分解过程的活化能,以脱水过程的活化能对原子序数作图呈“斜W效应”。用DSC测定了稀土乙酸盐脱水、分解过程的焓变。

EVALUATION OF THE EFFECT OF WAVELENGTH POSITIONING ERRORS ON KALMAN FILTERING RESULTS IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

This work evaluates the effect of wavelength positioning errors in spectral scans on analytical results when the Kalman filtering technique is used for the correction of line interferences in inductively coupled plasma atomic emission spectrometry (ICP-AES). The results show that a positioning accuracy of 0.1 pm is required in order to obtain accurate and precise estimates for analyte concentrations. The positioning error in sample scans is more crucial than that in model scans. The relative bias in measured analyte concentration originating from a positioning error in a sample scan increases linearly with an increase in the magnitude of the error and the peak distance of the overlapping lines, but is inversely proportional to the signal-to-background ratio. By the use of an optimization procedure for the positions of scans with the innovations number as the criterion, the wavelength positioning error can be reduced and, correspondingly, the accuracy and precision of analytical results improved.

INVESTIGATION OF PHASE SEPARATION BEHAVIOR IN POLY (METHYL METHACRYLATE)/POLY (STYRENE-CO-ACRYLONITRILE) MIXTURES WITH PULSED NUCLEAR MAGNETIC RESONANCE

Thermally induced phase separation in the mixture of poly (methyl methacrylate) (PMMA) with poly(styrene-co-acrylonitite (SAN) has intern studied with pulsed nuclear magnetic resonance(NMR) in single spin-lattice retaxation time T-1 of the eornpatibl. mixture two T-1 corresponding to those of PM MA-rich and SAN-rich comairis. Meanwhile, both T-1 gradually changing with annealing time provides the direct evidence that the phase separation takes place with a decomposition mechanism. Diffusion coeffieient was to lac negative, indicating an uphal diffusion characteristics, The basic parameters governing its kinetics were estimated using NMR date which were in good agreement with those evaluated from time-resolved light scattering experiments for a 60/40(PMMA/SAN) mixture annealed at 180.0 degrees C.

CYCLIC VOLTAMMETRIC STUDY ON THE TRANSFER MECHANISM OF ALKALI-METAL IONS ACROSS LIQUID LIQUID INTERFACE FACILITATED BY TRITON X-100

The transfer behavior of alkali motal ions K~+ and Na~+ across the interfaces of water/nitrobenzene and water/1, 2-dichloroethane facilitated by Triton X-100 is investigated by cyclic voltammetry with four electrodes. The equations of interfacial half-wave potential derived in terms of the mechanism proposed isverified by the experimental data and consistent with the practical △_0~wφ_p-pM curves.

稀土L-半胱氨酸配合物的红外光谱和X光电子能谱研究

本文报道14种稀土元素和L-半胱氨酸(L-cys)的固态配合物,(RE(cys)_3Cl_3·3H_2O,RE=Ce-Lu、Y,Pm���外),并根据它们的红外光谱和XPS能谱对配合物的配位方式进行了讨论。

A key gene of the RNA interference pathway in the black tiger shrimp, Penaeus monodon: Identification and functional characterisation of Dicer-1

RNA interference (RNAi) is an evolutionarily conserved mechanism by which double-stranded RNA (dsRNA) initiates post-transcriptional silencing of homologous genes. Here we report the amplification and characterisation of a full length cDNA from black tiger shrimp (Penaeus monodon) that encodes the bidentate RNAase III Dicer, a key component of the RNAi pathway. The full length of the shrimp Dicer (Pm Dcr1) cDNA is 7629 bp in length, including a 51 untranslated region (UTR) of 130 bp, a 3' UTR of 77 bp, and an open reading frame of 7422 bp encoding a polypeptide of 2473 amino acids with an estimated molecular mass of 277.895 kDa and a predicted isoelectric point of 4.86. Analysis of the deduced amino acid sequence indicated that the mature peptide contains all the seven recognised functional domains and is most similar to the mosquito (Aedes aegypti) Dicer-1 sequence with a similarity of 34.6%. Quantitative RT-PCR analysis showed that Pm Dcr1 mRNA is most highly expressed in haemolymph and lymphoid organ tissues (P 0.05). However, there was no correlation between Pm Dcr1 mRNA levels in lymphoid organ and the viral genetic loads in shrimp naturally infected with gill-associated virus (GAV) and Mourilyan virus (P > 0.05). Treatment with synthetic dsRNA corresponding to Pm Dcr1 sequence resulted in knock-down of Pm Dcr1 mRNA expression in both uninfected shrimp and shrimp infected experimentally with GAV. Knock-down of Pm Dcr1 expression resulted in more rapid mortalities and higher viral loads. These data demonstrated that Dicer is involved in antiviral defence in shrimp. (c) 2007 Elsevier Ltd. All rights reserved.