Growth and optical characteristics of Ce-doped and Ce : Na-codoped BaLiF3 single crystals

Ce-doped and Ce : Na-codoped BaLiF₃ single crystals were grown by the Czochralski technique under reactive atmosphere. Na⁺-ions, used as a charge-compensating impurity, compete with Ce³⁺-ions for Ba²⁺ sites in the host, reducing the Ce³⁺ incorporation and degrading the mechanical integrity of crystals. Ce-doped BaLiF₃ showed potential for UV tunable lasers.     

离子色谱法测定减水剂中的阴离子

建立一种离子色谱法同时测定减水剂中的葡萄糖酸根、氯离子、硫酸根、硫代硫酸根.样品经过稀释、C18小柱预处理后直接进样.选用shodex52-4e阴离子交换柱分离样品,淋洗液为3.6mmol·L^-1Na₂CO₃,柱温50℃,流速0.8mL·min^-1,进样量7μL,抑制电导检测,外标法定量,当葡萄糖酸根、氯离子、硫酸根、硫代硫酸根的质量分数分别为5.0~100.0,0.1~30.0,1.0~50.0,1.0~50.0mg·L^-1时,与色谱峰面积呈良好的线性关系(r≥0.9991),相对标准偏差(n=7)均小于2.5%,检出限在50.23~13.44μg·L^-1.将该方法应用于减水剂阴离子的测定,加标回收率在80.6%~113.9%,方法选择性高、灵敏度好且操作简便.     

建筑垃圾再生混凝土的性价比研究

为了能够有效进行材料力学性能及成本耗费的比较研究, 提出了价格-强度比和价格-模量比两个衡量指标. 在再生混凝土材料体系设计方面, 骨料取自建筑垃圾混凝土, 选取了砂率分别为30%、37%和39%的3种材料体系. 通过添加不同比例的矿物掺合料, 形成了不同的材料配合比. 通过一维应力压缩实验, 得到了材料的模量和强度. 通过比较价格-强度比和价格-模量比的定量结果, 得到了性价比最优的材料配合比设计. 研究结果对于合理利用建筑垃圾形成力学性能优良的再生混凝土具有参考意义.     

Reducing subspaces of multiplication operators on function spaces

This survey presents the brief history and recent development on commutants and reducing subspaces of multiplication operators on both the Hardy space and the Bergman space, and von Neumann algebras generated by multiplication operators on the Bergman space.     

Substitution effect on the intermolecular halogen and hydrogen bonds of the σ‐bonded fluorinated pyridine···XY/HX complexes (XY = F2, Cl2, ClF; HX = HF,HCl)

Optimal structures, electronic and thermodynamic properties of the title complexes are presented. The stability of the hydrogen bonded systems is enhanced by the increasing dipole moments whereas in the halogen bonded systems it is also affected by the atom size in the diatomics. The consecutive addition of fluorine atoms to the pyridine moiety results in the decrease of the interaction energy for both types of the investigated bonds. The substitution on the meta sites in pyridine leads to more stable complexes than the substitution in the ortho position. The role of substitution on electric polarization and electrostatic forces is estimated by the symmetry‐adapted perturbation theory energy decomposition. The predicted Gibbs free energies of the complexes of mono fluorinated pyridines with HCl, HF, and ClF are from ?12 to ?22 kJ mol^?1 at 200 K. The possible experimental identification of the complexes with respect to the vibrational modes is discussed. © 2014 Wiley Periodicals, Inc.     

Combined HPLC-CUPRAC (cupric ion reducing antioxidant capacity) assay of parsley, celery leaves, and nettle

This study aims to identify the essential antioxidant compounds present in parsley (Petroselinum sativum) and celery (Apium graveolens) leaves belonging to the Umbelliferae (Apiaceae) family, and in stinging nettle (Urtica dioica) belonging to Urticaceae family, to measure the total antioxidant capacity (TAC) of these compounds with CUPRAC (cupric ion reducing antioxidant capacity) and ABTS spectrophotometric methods, and to correlate the TAC with high performance liquid chromatography (HPLC) findings. The CUPRAC spectrophotometric method of TAC assay using copper(II)-neocuproine (2,9-dimethyl-1,10-phenanthroline) as the chromogenic oxidant was developed in our laboratories. The individual antioxidant constituents of plant extracts were identified and quantified by HPLC on a C18 column using a modified mobile phase of gradient elution comprised of MeOH-0.2% o-phosphoric acid and UV detection for polyphenols at 280 nm. The TAC values of HPLC-quantified antioxidant constituents were found, and compared for the first time with those found by CUPRAC. The TAC of HPLC-quantified compounds accounted for a relatively high percentage of the observed CUPRAC capacities of plant extracts, namely 81% of nettle, 60-77% of parsley (in different hydrolyzates of extract and solid sample), and 41-57% of celery leaves (in different hydrolyzates). The CUPRAC total capacities of the 70% MeOH extracts of studied plants (in the units of mmol trolox g⁻¹ plant) were in the order: celery leaves > nettle > parsley. The TAC calculated with the aid of HPLC-spectrophotometry did not compensate for 100% of the CUPRAC total capacities, because all flavonoid glycosides subjected to hydrolysis were either not detectable with HPLC, or not converted to the corresponding aglycons (i.e., easily detectable and quantifiable with HPLC) during the hydrolysis step.     

In situ Raman spectroscopy studies on chromium oxide catalyst in an anhydrous hydrogen fluoride atmosphere

Changes of different chromium oxide species [Cr(VI), Cr(V) and Cr(III)] were investigated using in situ Raman spectroscopy in an anhydrous hydrogen fluoride (AHF) atmosphere. It was found that the Cr(VI) (CrO₃) and Cr(V) (YCrO₄) species were easy to fluorinate, and generated CrO₂F₂ or/and CrOF₃, while the Cr(III) (Cr₂O₃) species was difficult to fluorinate. Moreover, the CrO₂F₂ and CrOF₃ species were stable in the AHF atmosphere, but they easily transform into CrO₃ in N₂ atmosphere and further decomposed to Cr₂O₃ at 400 °C. Moreover, Cl/F exchange reaction of CF₃CH₂Cl to CF₃CH₂F over these Cr species indicated that the high‐oxidation‐state CrO_xF_y (CrO₂F₂ and CrOF₃) species exhibited much higher reactivities than Cr₂O₃, suggesting that these species (CrO₂F₂ and CrOF₃) may be the active phases of the reaction. Copyright © 2010 John Wiley & Sons, Ltd.     

不需要校准激光的法-帕仪中高层大气温度反演方法和观测数据初步分析

本文提出了一种根据FPI观测不需要校准激光而进行温度反演的方法, 给出了进行温度反演的解的解析形式. 依据武汉大学FPI大气温度测量系统获得的630 nm和557.7 nm观测数据, 利用上述方法进行温度反演, 结果表明本文方法不需要校准激光, 能用于不同波长的FPI温度反演.     

成都市大气颗粒物的特性研究

以成都市东区为研究区域，研究了该区总悬浮颗粒物（哪）含量及其中重金属的含量随季节变化的特征，通过粉煤灰与哪中重金属含量的关系、富集因子分析来判断颗粒物中重金属的来源。研究表明，TSP及其中重金属的含量随季节变化明显且特征相似；哪的含量严重超标；由监测结果大致推断出了该区域哪及其中重金属的主要来源。     

Quantitative analysis of cellulose-reducing ends

Methods for the quantification of total and accessible reducing ends on traditional cellulose substrates have been evaluated because of their relevance to enzyme-catalyzed cellulose saccharification. For example, quantification of accessible reducing ends is likely to be the most direct measure of substrate concentration for the exo-acting, reducing end-preferring cellobiohydrolases. Two colorimetric assays (dinitrosalicylic acid [DNS] and bicinchoninic acid [BCA] assay) and a radioisotope approach (NaB³H₄ labeling) were evaluated for this application. Cellulose substrates included microcrystalline celluloses, bacterial celluloses, and filter paper. Estimates of the number of reducing ends per unit mass cellulose were found to be dependent on the assay system (i.e. the DNS and BCA assays gave strikingly different results). DNS-based values were several-fold higher than those obtained using the BCA assay, with fold-differences being substrate specific. Sodium borohydride reduction of celluloses, using cold or radiolabeled reagent under relatively mild conditions, was used to assess the number of surface (solvent-accessible) reducing ends. The results indicate that 30–40% of the reducing ends on traditional cellulose substrates are not solvent accessible; that is, they are buried in the interior of cellulose structures and thus not available to exo-acting enzymes.