Harmonic 2-forms and positively curved 4-manifolds

Science China Mathematics - We prove that if a compact Riemannian 4-manifold with positive sectional curvature satisfies a strengthened Kato type inequality, then it is definite. We also discuss...     

4一致反超图的最小边数问题

混合超图是在超图的基础上添加一个反超边得到的图．超边和反超边的区别主要体现在着色要求上．在着色中,要求每一超边至少要有两个点着不同的颜色,而每一反超边至少有两个点着相同的颜色．最大最小颜色数分别称为混合超图的上色数和下色数。本文主要研究反超图,即只含反超边的超图。讨论了上色数为3的4一致超图的最小边数问题．给出了上色数为3的4一致反超图的最小边数的一个上界和一个下界．     

3-正则图的分割问题是NP-完全问题

证明了3-正则图的最小平分问题和最小α-分割问题都是NP-完全问题.     

Adsorption of uranium from aqueous solution by graphene oxide nanosheets supported on sepiolite

Adsorptive behavior of uranium from aqueous solution on graphene oxide supported on sepiolite composites (GO@sepiolite composites) as a function of pH, ionic strength, temperature and initial uranium concentration was carried out by the batch techniques. GO@sepiolite composites was synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and potentiometric acid–base titration. According to XRD patterns and SEM images, the graphene oxide nanosheets were grafted on sepiolite surface successfully. The macroscopic results showed that the adsorption of uranium on GO@sepiolite composites was significantly depended on pH, whereas no effect of ionic strength on uranium adsorption at high pH and high ionic strength conditions was observed. The uptake equilibrium is best described by Langmuir adsorption isotherm, and the maximum adsorption capacity (Q_e) of GO@sepiolite composites at pH 5.0 and T = 298 K were calculated to be 161.29 mg/g. Thermodynamic results indicated that the adsorption of uranium on GO@sepiolite composites is the spontaneous and exothermic process.     

原位合成H2O2在水处理技术中的应用研究进展

从过氧化氢(H₂O₂)的原位生成技术角度总结了近年来利用原位合成H₂O₂处理水中污染物的研究,分析了当前可充当氢源材料的种类及不同的氢源材料对于提高H₂O₂产率的影响,以及不同的催化剂材料和催化反应环境提高H₂O₂利用率对污染处理效果的影响因素,并对原位合成H₂O₂在水处理领域中面临的挑战和发展前景做了展望,从而为该技术的大规模应用提供指导和借鉴。     

混合胺体系中 MCM-49/ZSM-35 复合分子筛的晶化过程

 采用 X 射线衍射、N2 吸附-脱附、扫描电镜和傅里叶变换红外光谱等技术, 研究了 MCM-49/ZSM-35 复合分子筛在 Na2O-SiO2-Al2O3-CHA (环己胺)-HMI (六亚甲基亚胺)-H2O 合成体系中, 先在低温 80 ?C 老化 4 h, 再经 160 ?C 晶化不同时间的演变过程. 结果表明, 在该混合胺体系中, 首先生成 MCM-49 分子筛, 随着晶化时间的延长, 形成 ZSM-35 含量逐渐增加的 MCM-49/ZSM-35 复合分子筛, 最后生成纯 ZSM-35 分子筛; ZSM-35 的生成是以 MCM-49 分子筛的消耗为代价的.     

多孔介质中气体水合物降压分解的分形理论研究

通过将水合物的分解过程看作是无固态产物层生成的气固反应过程, 结合粒径缩小的收缩核反应模型和分形理论, 建立了多孔介质中水合物降压分解的分数维动力学模型, 提出了基于水合物分解实验数据计算多孔介质分形维数的方法. 分别利用前人的甲烷水合物和CO2水合物降压分解实验数据, 对上述分数维动力学模型进行了验证. 计算结果表明, 用提出的方法所计算得到的多孔介质分形维数与前人的测定结果基本符合; 对甲烷水合物和CO2水合物的降压分解过程, 提出的分数维动力学分解模型得出了和实验结果基本一致的预测, 绝对平均误差(AAD)小于10%.     

Geometric aspects of the moduli space of Riemann surfaces

We describe some recent progress in the study of moduli space of Riemann surfaces in this survey paper. New complete Kahler metrics were introduced on the moduli space and Teichmuller space. Their curvature properties and asymptotic behavior were studied in details. These natural metrics served as bridges to connect all the known canonical metrics, especially the Kahler-Einstein metric. We showed that all the known complete metrics on the moduli space are equivalent and have Poincare type growth. Furthermore, the Kahler-Einstein metric has strongly bounded geometry. This also implied that the logarithm cotangent bundle of the moduli space is stable in the sense of Mumford.     

ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

1. INTRODUCTION In some cities of China, cancer and breath system diseases caused by the pollution of volatile organic compounds (VOCs) have been obviously increasing. The VOCs includes BTEX (benzene, toluene, ethylbenzene, and xylene), aldehydes, cresol, phenol, acetic acid, polynuclear aromatic hydrocarbons (PAHs), which have long-term human health implications. Emission of the VOCs has threatened the health of people seriously [1,2]. The pollution of the VOCs mostly hails from…     

DL－32／16型多路时间间隔测量仪及其应用

基于模拟内插原理，研制了一种精密多路时间间隔测量仪。该仪器有一个公共起始通道和３２或１６路停止通道，测时范围５０ｎｓ～８２０ｍｓ，分辨力１ｎｓ，精度优于±５ｎｓ。由于采用了内部微处理器，仪器具有内部自检、通道识别、差错指示和测量数据自动显示，打印、处理及掉电保护等功能，并能给出多次测量的平均值、最大值和最小值。实验测量了Ｔ／Γ炸药的爆速和钨合金中的冲击波速度，得到满意的结果。