动态冰浆传热特性的研究

动态冰浆由于具有较强的蓄能和传热能力,日益受到人们的重视。文中建立了动态冰浆传热特性的数理模型,并利用已知的载流溶液和冰晶的物性参数,得到了动态冰浆在水平直管、等热流加热条件下的传热系数,根据计算结果,分析了传热系数随着冰浆浓度的变化的规律和冰浆流速和管径对动态冰浆传热性能的影响。     

基于FPGA的DDS设计方法

介绍了一种基于FPGA的DDS设计方法,结合DDS的原理,给出了具体设计程序以及仿真波形。基于FPGA的DDS与传统的专业DDS芯片相比具有电路简单、输出波形调整灵活以及性价比高等特点。     

算子Dα及其刻划的亚纯p叶函数类

用算子Dα刻划了亚纯星象函数,亚纯凸象函数,亚纯近于凸函数和亚纯拟凸函数的新子类,建立了包含关系,讨论了这些类中函数积分算子的性质.     

Anthraquinones from the Aerial Parts of Rubia cordifolia with Their NO Inhibitory and Antibacterial Activities

The present study aimed to identify the composition of the aerial parts of Rubia cordifolia L. A chemical investigation on the EtOAc extracts from the aerial parts of Rubia cordifolia resulted in the isolation of four new anthraquinones, namely Cordifoquinone A–D (1–4), along with 16 known anthraquinones. Their structures were elucidated on the basis of NMR and HR-ESIMS data. All isolates were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 1, 3 and 10 exhibited significant inhibitory activities with IC₅₀ values of 14.05, 23.48 and 29.23 μmol·L⁻¹, respectively. Their antibacterial activities of four bacteria, Escherichia coli (ATCC 25922), Staphylococcus aureus subsp. aureus (ATCC 29213), Salmonella enterica subsp. enterica (ATCC 14028) and Pseudomonas aeruginosa (ATCC 27853), were also evaluated. Our results indicated that the antibacterial activity of these compounds is inactive.     

Design,Synthesis, and Cytotoxic Activity of Novel Natural Arylsulfonamide-Inspired Molecules

Primary arylsulfonamide functional groups feature prominently in diverse pharmaceuticals. However, natural arylsulfonamides are relatively infrequent. In this work, two novel arylsulfonamide natural products were first synthesized, and then a series of novel molecules derived from natural arylsulfonamides were designed and synthesized, and their in vitro cytotoxic activities against A875, HepG2, and MARC145 cell lines were systematically evaluated. The results indicate that some of these arylsulfonamide derivatives exhibit significantly good cytotoxic activity against the tested cell lines compared with the control 5-fluorouracil (5-FU), such as compounds 10l, 10p, 10q, and 10r. In particular, the potential molecule 10q, containing a carbazole moiety, exhibited the highest inhibitory activity against all tested cell lines, with IC₅₀ values of 4.19 ± 0.78, 3.55 ± 0.63, and 2.95 ± 0.78 μg/mL, respectively. This will offer the potential to discover novel drug-like compounds from the sparsely populated area of natural products that can lead to effective anticancer agents.     

室温离子液体在分离分析中的应用

室温离子液体是指室温或接近室温下全部由离子组成的有机液体物质,具有不挥发,不易燃,溶解范围大,对空气和热稳定等特点,作为一种“可设计”型的环境相对友好溶剂,已被成功应用于分离分析领域中。本文重点综述了离子液体近年来在毛细管电泳、液相色谱及气相色谱中的应用进展,也对离子液体在质谱和光谱中的应用作了介绍。     

气相色谱-质谱法测定电子电气产品中多溴二苯醚及多溴联苯

建立了利用气相色谱-质谱测定电子、电气产品中多溴二苯醚及多溴苯的方法。对样品的粉碎、提取方法、色谱柱的选择、测定条件进行研究,并自建标准质谱图库;采用保留时间、Br同位素规则、质谱特征离子、谱库检索等4种方式相结合进行定性,避免了假阳性及漏检的情况,结果更加准确可靠。本法检出限为5mg/kg,PBDEs的回收率为91.3%,PBBs的回收率为92.5%,相对标准偏差(RSD)为4.3%。与现有方法相比,本法分离时间最短(6min),具有简便快速、实用性强、灵敏度高、准确可靠等特点,适用于电子电气产品、塑料、橡胶、汽车内饰材料等的溴系阻燃剂分析,满足欧盟RoHS指令检测的要求。     

液相色谱-质谱法测定纺织品和皮革制品中痕量全氟辛烷磺酸盐

建立了纺织品和皮革制品中全氟辛烷磺酸盐(PFOS)的液相色谱-二级质谱(LC-MS2)测定方法。样品经0.1mol/L HCl和甲醇超声波振荡提取,高效液相色谱分离;色谱柱为Zorbax SB-C18;流动相为V(甲醇)∶V(10mmol/L乙酸铵水溶液)=70∶30,流速为0.3mL/min。采用负离子模式的电喷雾质谱检测。以一级质谱得到的准分子离子m/z499作为母离子,进行二级质谱(MS2)分析。选择MS2的碎片离子m/z169、230、280、330及419定性确证,MS2总离子流色谱(TIC)峰面积定量。实验优化了样品提取方法和色谱、质谱条件,并对二级质谱碎裂机理和特征离子进行了研究。结果表明,本法简便快速,准确可靠,相对标准偏差小于8.6%,回收率在90%~99%之间;检出限为1.5mg/kg,远低于欧盟指令50mg/kg的限量规定。本方法已成功应用于纺织品、皮革制品中痕量PFOS的测定。     

钪与氧空位共掺杂锐钛矿相TiO2的形成能与电子结构的第一性原理研究

采用基于密度泛函理论的第一性原理研究了钪(Sc)、氧空位(O_V)单/共掺杂锐钛矿相TiO₂,对晶体结构、形成能以及电子结构进行了对比分析.研究结果表明,Sc-TiO₂在富氧环境下缺陷形成能为负值,富钛环境下缺陷形成能为正值,表明Sc-TiO₂只能在富氧环境下制备;O_V-TiO₂、Sc-O_V-TiO₂在富氧或富钛环境下缺陷形成能均为负值,但富氧环境下形成能更低;O_V-TiO₂的0/1-缺陷电荷转变能级为深能级,而Sc-TiO₂的0/1-缺陷电荷转变能级则属于相对较浅能级;与纯锐钛矿相TiO₂相比,Sc-TiO₂的禁带宽度略有减小,但O_V-TiO₂、Sc-O_V-TiO₂禁带宽度变宽.     

稀土X (X=La、Ce、Pr、Nd)修饰单层h-MoS2的NO气敏性

为提高h-MoS₂对NO的气敏性,采用第一性原理研究了X(X=La、Ce、Pr和Nd)对h-MoS₂的稳定性、吸附特性、功函数和伏安特性的影响.研究结果表明：X(X=La、Ce、Pr和Nd)取代Mo原子后得到的形成能均为负,说明掺杂体系容易形成且稳定存在.同时X掺杂后的h-MoS₂布居数相比于未掺杂前的大,也说明掺杂有利于体系稳定.NO吸附在La、Ce原子顶部位置的吸附能为-1.215 eV、-1.225 eV,吸附距离分别为2.475?、2.854?,具有明显的化学吸附特征.同时Hirshfeld转移电荷分别为0.213e和0.325e,具有明显的受体特征,提高了气敏性.La和Ce掺杂后能明显改变功函数的大小,也说明La和Ce能提高h-MoS₂对NO的气敏性.施加电场后能有效提高Pr掺杂体系的吸附强度,增大Hirshfeld转移电荷,对功函数的改变最大,所以电场对Pr掺杂体系的影响非常明显.通过分析掺杂体系的伏安特性曲线,La、Ce两掺杂体系的电流分别由0增大到5.3μA和4.8μA,而Pr、Nd...