A NEW PEAK (T_4) IN THE ~(13)C-NMR SPECTRUM OF POLYBUTADIENE

A new peak at 39.0 ppm in the ~(13)C-NMR spectrum of polybutadiene (PBD) was discovered. This peak is assigned to the fourth peak (T_4) of trans-1,4-sequence marked with an asterisk as shown in Fig. 3 in the text.The occurrence of T_4 carbon nuclei is strongly affected by their neighboring 1,2-units. So long as both contents of trans-1,4- and 1,2-units attain their proper amounts the peak (T_4) with appear in the ~(13)C-NMR spectrum of PBD.     

A Novel Method for the Determination of Fungicide Residues in Tobacco by Ultra-performance Liquid Chromatography–Tandem Mass Spectrometry Combined with Pass-Through Solid-Phase Extraction

Chromatographia - A novel method for the rapid simultaneous determination of multiple fungicide residues in tobacco was established using ultra-performance liquid chromatography–tandem mass...     

导电聚合物与锂二次电池

本文对聚合物的锂二次电池原理，发展、应用前景及今后的展望做了评述．     

自成核对聚对苯二甲酸1,3-丙二酯结晶行为的影响

The effects of self-seeding nucleation on the crystallization behavior and properties of poly( trimethylene terephthalale) were studied. Differential scanning calorimetry (DSC) results indicated that the crystallization temperature of paly(trimethylene terephthalate) increased obviously(increased about 20℃) after the process of selfseeding nucleation. The results of polarized light microscopy (PLM) showed that the spherulite size decreased markedly from 40μm to 8μm.     

Studies of left-handed Z DNA: Characteristics of Raman spectra of d(GpCpGpCpGpC)

Studies of laser Raman spectra of synthesized DNA fragment, d (GpCpGpCpGpC), were performed. The similarities and differences between the characteristic spectra of the oligomer and those of its structural components, 5′-dGMP and 5′-dCMP, were dis cussed. The information obtained on the characteristic Raman spectrum susceptible to B-Z conformation transition of oligomer might be helpful in further investigation of the biology of left-handed DNA.     

Numerical analysis and synthesis of electron-optical systems of complex structure

The problem of the numerical analysis of the electrostatic field of individual elements in complex three-dimensional electron-optical systems is considered. Zh. Tekh. Fiz. 68, 97–103 (February 1998)     

Allowance for wideband parameter fluctuations in linear inertial networks

A method is developed for analysis of linear inertial networks that undergo parameter fluctuations over a wide detuning range (up to the carrier frequency). Frequency fluctuations caused by reactive-parameter perturbations in LC and tapped-capacitor oscillators are determined as an illustration.Nizhny Novgorod State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 36, No. 10, pp. 936–941, October, 1993.     

Magnetostriction and thermal expansion anomalies near the Curie point of the compound La0.7Sr0.3MnO3 with the perovskite structure

It is found that the bulk part ω of the magnetostriction near the Curie temperature T _c in a La_0.7Sr_0.3MnO₃ single crystal with the perovskite structure is negative and that the temperature dependence of |ω| has a maximum near T _c . The quantity |ω| at the maximum increases rapidly with increasing magnetic field. The thermal expansion coefficient near T c increases with temperature much faster than linearly. The paramagnetic Curie temperature determined from the Curie-Weiss law, which the paramagnetic susceptibility of this crystal satifies, was found to be lower than T _c . These anomalies and also the near-T _c metal-insulator transition which is characteristic for this material are explained by the existence of a magnetically two-phase state consisting of a conducting ferromagnetic matrix containing antiferromagnetic insulating microregions occupying not more than 5% of the sample volume. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 6, 449–453 (25 March 1997)     

Application of the Bogolyubov inequality for the calculation of the thermodynamic properties of diatomic molecules

The frequency of vibration and the interatomic distance are considered as variational parameters in an approximate expression for the free energy of a diatomic molecule. Application of the Bogolyubov inequality allows one to find the dependence of these parameters on temperature. Calculations are given for the molecules HF and HgH.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 6–8, January, 1982.