若干激光基质材料的晶纤生长及荧光性能

制备了以ZrO_2,Gd_2O_2,LiNbO_3或YAG为基质,具有不同掺杂离子的12个单晶纤维试样,还测量了这些试样的化学成份及荧光光谱。     

Reductive alkylation of illinois No. 6 coal. 1H and 13C n.m.r. spectra of the 13C-enriched alkylation products

The reductive alkylation of Illinois No. 6 coal has been carried out using potassium and naphthalene in tetrahydrofuran and methyl-¹³C and butyl-1 -¹³C iodides to alkylate the resultant polyanion. The soluble products of the reductive alkylation reaction were isolated by extraction and chromatography. Proton and carbon n.m.r. spectra were recorded. The intense resonance signal at δ3.95 which appears in the proton n.m.r. spectra of Illinois No. 6 coal butylated with unenriched butyl iodide is split into a doublet by the ¹³C nuclei. Similar results were obtained for the methylation products. The chemical shift and coupling interaction establish that aryl ethers are a very important constituent of the alkylated coal. The carbon n.m.r. spectra of the coal alkylated with ¹³C-enriched alkyl iodides are intense. The resonances of the C-alkylation products appear in a single broad band with a maximum intensity in spectral regions compatible with the formation of the reductive alkylation products of certain polynuclear aromatic hydrocarbons or the base-catalysed alkylation of certain benzylic carbon atoms. The resonances of the N -alkylation products appear in two distinct bands. These resonances are tentatively assigned to amines produced as a result of reductive alkylation of heterocyclic compounds. The resonances of the 0-alkylation products appear in three distinct bands which can be assigned to alkyl aryl ethers, alkyl aryl ethers with substituents at the adjacent positions, and to alkyl carboxylates. The ratio of ethers to carboxylates in the soluble alkylation products was determined to be 7.8 for butylation and 8.0 for methylation. The Chromatographic fractions contain different amounts of C-, N-, and 0-alkylation products. This finding suggests that the coal structure is not highly uniform.     

单溴四苯基卟啉吸附在AgCl溶胶表面性质研究

合成了单溴四苯基卟啉—— 5 - (邻溴苯基 ) - 1 0 ,1 5 ,2 0 -三苯基卟啉 (H2 L) ,用元素分析 ,红外光谱、电子吸收光谱和氢核磁共振谱确定了其组成和结构。研究了 H2 L在醋酸中电子吸收光谱和在 Ag Cl溶胶上的表面化学反应。结果表明 ,单邻溴四苯基卟啉在冰醋酸中以二酸形式 H4 L2 + 和游离碱 H2 L形式存在 ,二者之间存在着电离平衡 :H4 L2 + =H2 L+2 H+ ;当 p H=7.0～ 1 1 .0时 ,H2 L在Ag Cl溶胶表面发生配位反应生成 Ag( ) L,并且溶液的 p H增大 ,配位反应的速率增大。     

4种喹诺酮类药物分子荧光光谱的量子化学研究

喹诺酮类药物是目前广泛用于治疗各种感染性疾病的化学合成药物。文章采用量子化学B3LYP方法,在6-31g基组水平下对4种喹诺酮类药物进行几何构型优化,经振动分析,均未出现虚频率。在此基础上用CIS方法计算了4种化合物的荧光光谱,所得计算值与实验值基本相符。     

Incoherent scatter spectra due to HF heating in the low ionosphere region

The electron velocity distribution function and the incoherent scatter spectra during ionospheric heating in low ionosphere region are presented with consideration of the elastic collision between electrons and neural particles and the excitation of rotation energy level. The effects of pump frequency and electric fields on the spectra are discussed. With the increase of electric field, the non-Maxwellian feature is enhanced, and with the increase of heating frequency, the non-Maxwellian feature is weakened. The non-Maxwellian factor will bring a large error in ionosphere parameters, which must be considered in the inversion. Supported by the National Natural Science Foundation of China (Grant No. 40310223), the National Key Laboratory of Electromagnetic Environment (LEME), and National Key Technologies R&D Program of China (Grant No. 2006BAB18B06)     

ANALYTICAL SOLUTIONS FOR PEELING USING BEAM-ON-FOUNDATION MODEL AND COHESIVE ZONE

When fibrillation occurs during peeling, the normal stress in the adhesive may gradually reduce to zero at the peel front. The shear stress also reduces to zero. Classical beam-spring (or beam-on-elastic-foundation) models do not yield solutions that have these properties. With the use of a beam-on-foundation model combined with a cohesive zone in the neighborhood of the peel front, these properties can be satisfied. In order to obtain analytical solutions, peel tests are considered in which the backing has a small slope and is linearly elastic in the adhered region, and the traction law is assumed to be piecewise linear. Cases are considered with only normal stresses in the adhesive (mode I), only shear stresses (mode II), and both stresses coupled (mixed-mode behavior). Analytical solutions are obtained for displacements of the backing, forces in the backing, and stresses between the adhesive and the backing.     

掺铕铌酸锂晶体的M■ssbauer谱

测量了Ｅｕ：ＬｉＮｂＯ_３和（Ｅｕ，Ｍｇ）：ＬｉＮｂＯ_３的Ｍｓｓｂａｕｅｒ谱，并对数据进行了拟合。根据拟合结果和ＬｉＮｂＯ_３晶体结构的特征，讨论了Ｅｕ~（３＋）在晶格中的占位，并以Ｅｕ~（３＋）的参数为探针．讨论了Ｍｇ（２＋）在晶格中的占位。     

Crystal structure,phonon modes,and bond characteristics of AgPb2B2V3O12 (B = Mg,Zn) microwave ceramics

AgPb₂B₂V₃O₁₂ (B = Mg, Zn) ceramics with low sintering temperature were synthesized via the conventional solid-state reaction route. Rietveld refinements of the X-ray diffraction patterns confirm cubic symmetry with space group . The number of observed vibrational modes and those predicted by group theoretical calculations also confirm the space group. At the optimum sintering temperature of 750°C/4 hours, AgPb₂Mg₂V₃O₁₂ has a relative permittivity of 23.3 ± 0.2, unloaded quality factor () of 26 900 ± 500 GHz (), and temperature coefficient of resonant frequency of 19.3 ± 1 ppm/°C, while AgPb₂Zn₂V₃O₁₂ has the corresponding values of 26.4 ± 0.2, 28 400 ± 500 GHz () and –18.4 ± 1 ppm/°C at 590°C/4 hours. Microwave dielectric properties of a few reported garnets and Pb₂AgB₂V₃O₁₂ (B = Mg, Zn) ceramics were correlated with their intrinsic characteristics such as the Raman shifts as well as width of A_1g Raman bands. Higher quality factor was obtained for lower full width at half-maxima (FWHMs) values of A_1g modes. The increase in B-site bond valence contributes to high and low |τ_f| with the substitution of Zn²⁺ by Mg²⁺. Furthermore, the high ionic polarizability and unit cell volume with Zn²⁺substitution contribute to increased relative permittivity.     

Raman spectroscopy studies of concentrated vanadium redox battery positive electrolytes

Spectroscopic changes in highly concentrated vanadium(V)-sulfate solutions to be used in the vanadium redox battery are consistent with the presence of more than one V(V)-sulfate species. The results of Raman spectroscopy indicate that the major species in highly acidic conditions are VO₂SO₄ ^–, VO₂(SO₄)₂ ^3–, VO₂(HSO₄)₂ ^–, VO₃ ^–, V(V) dimers with V₂O₃ ⁴⁺ and V₂O₄ ²⁺ central units. The nature and amount of these species depends upon the V(V) and total sulfate concentrations as well as on S to V and H⁺ to V ratios in the positive half-cell electrolyte. V(V) forms V₂O₃ ⁴⁺, VO₂(SO₄)₂ ^3– and their copolymer species at higher total sulfate concentrations, which tends to stabilize the vanadium (V) positive electrolyte in the vanadium redox battery. The V(V) and V(IV) species show the least interaction with each other. Ageing of concentrated V(V) solutions at elevated temperature (50 °C) produces decomposition of species causing formation of V₂O₅ precipitates with a decrease in the amount of vanadium polymer.     

Synthesis and characterization of poly(urethane‐ester)s based on calcium salt of mono(hydroxybutyl)phthalate

Calcium‐containing poly(urethane‐ester)s (PUEs) were prepared by reacting diisocyanate (HMDI or TDI) with a mixture of calcium salt of mono(hydroxybutyl)phthalate [Ca(HBP)₂] and hydroxyl‐terminated poly(1,4‐butylene glutarate) [HTPBG₁₀₀₀], using di‐n‐butyltin‐dilaurate as catalyst. About six calcium‐containing PUEs having different composition were synthesized by taking the mole ratio of Ca(HBP)₂:HTPBG₁₀₀₀:diisocyanate (HMDI or TDI) as 3:1:4, 2:2:4, and 1:3:4. Two blank PUEs were synthesized by the reaction of HTPBG₁₀₀₀ with diisocyanate (HMDI or TDI). The polymers were characterized by IR, ¹H NMR, Solid state ¹³C‐CP‐MAS NMR, TGA, DSC, XRD, solubility, and viscosity studies. The T_g value of PUEs increases with increase in the calcium content and decreases with increase in soft segment content. The viscosity of the calcium‐containing PUEs increases with increase in the soft segment content and decreases with increase in the calcium content. X‐ray diffraction patterns of the polymers show that the HMDI‐based polymers are partially crystalline and TDI‐based polymers are amorphous in nature. The dynamic mechanical analysis of the calcium‐containing PUEs based on HMDI shows that with increase in the calcium content of polymer, modulus (g′ and g″) increases at any given temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1720–1727, 2006