Secondary particle yields from 450 GeV/c protons on beryllium, a precise measurement for present and future neutrino beam calculations

Results on charged K and π production rates and their ratios measured by the SPY/NA56 experiment for 450 GeV/c proton interactions on beryllium targets are reported here. The present data sample covers the secondary particle momentum range between 7 GeV/c and 135 GeV/c in the forward direction. Experimental accuracies of 3% for K/π ratios and of 5–10% for particle yields have been achieved.     

具有四配位铁中心的微孔磷酸铁晶体的溶剂热合成与表征

在有机溶剂乙二醇中合成了具有三维骨架结构的磷酸铁晶体 ,对其进行了单晶结构解析 ,热重分析 ,穆斯堡尔谱以及红外光谱测试 ,证实晶体组成为 [NH3CH2 CH2 NH3]0 .5[FePO4 ],晶体结构属正交晶系 ,空间群Pc cn ,晶胞参数a =10 .36 1(6 ) ,b =10 .390 (5) ,c=9.135(7) ,V =983.3(11) 3,Z =8,Dc=2 .4 57Mg·m- 3,F(0 0 0 ) =72 8,R =0 .0 52 8,wR =0 .1194。在其结构中 ,磷氧四面体和铁氧四面体严格交替共用顶点在 [0 0 1]方向上形成八员环 ,双质子化的乙二胺分子占据八员环空隙。该晶体结构最为显著的特征是具有在磷酸盐中非常少见的四配位铁中心     

Solvothermal Synthesis and Characterization of Sheet Structure Containing Adamantane [Hg2Sn2S10]8– Anions

Sheet Rb2HgSnS4 was synthesized solvothermally and characterized by X-ray single crystal diffraction. The compound is comprised of sheets with admantane-like [Hg2Sn2S10]8– units. The crystals belong to the space group C2/c, with the unit cell parameters a=1.1063(2) nm, b=1.1071(2) nm, c=1.5741(3) nm, a=90°, β=100.13(3)°, γ=90°. A reflectance spectroscopy study reveals the nature of the semiconductor with an energy of 2.1 eV for the compound.     

铜-铈氧化还原液流电池性能

设计了一种新型Ce-Cu氧化-还原液流电池,研究了Ce³⁺/Ce⁴⁺和Cu⁰/Cu²⁺氧化还原电对的循环伏安特性,优化了电解液及电极材料,进而组装出液流电池,测试了电池的充放电性能。 结果表明,在45 mA恒电流充/放电条件下,电池放电平台电压约为1.0 V,库伦效率约100%,能量效率为75%以上,电池可稳定循环100次。     

气相色谱法测定土壤中酰胺类除草剂

建立了从土壤中同时提取甲草胺、乙草胺和丁草胺并采用气相色谱法测定的分析方法.采用丙酮-石油醚(2:1,V/V)为提取液,经弗罗里矽硅土固相萃取柱净化,超声30 min、振荡10 min.测定结果显示,甲草胺、乙草胺、丁草胺的保留时间分别为16.333,16.019,20.249 min;线性相关系数>0.9990;6个...     

高效液相色谱-串联质谱测定海水中氯霉素残留量

应用高效液相色谱-串联质谱法测定海水中的氯霉素残留量, 流动相为V(甲醇)∶V(水)＝80∶20. 采用负电喷雾离子源, 在多反应性监测模式下采集信号, 定性离子对为321/121、 321/152、 321/176, 定量离子对为321/152. 本方法的线性范围是0.1～100 μg/L, 相关系数为0.9993, 仪器检出限为0.01 μg/L, 回收率在81.7%～121.0%之间. 该方法适于海洋环境监测.     

Influence of Backbone Structure on Properties of Directly Polymerized Phenoxy Resins from Epichlorohydrin and Various Aromatic Dihydric Phenols Monomers

A series of phenoxy resins was directly prepared through the polymerization of each of the various aromatic dihydric phenols and epichlorohydrin.FTIR and 1H NMR spectra were recorded to characterize the structures of the re-sins.The GPC curves were used to determine the molecular weight distribution.In addition,the thermal properties of the resins were studied with differential scanning calorimetry(DSC)and thermal gravimetric analysis(TGA).The thermal stabilities of the polymers increased with the content of the benzene ring,pendant group increasing or biphenyl groups emerging.The adhesive properties of the polymers were evaluated in terms of the lap shear strength with Fe-Fe adherends.The fracture mechanisms were determined by SEM observation and it was found that there was an important participation of cohesive fracture mechanisms.Also,it has been demonstrated that the extension of these micro-cohesive mechanisms is directly correlated with the adhesive strength.According to these results,the phenoxy resin containing biphenyl groups presented a higher adhesive strength and could improve the adhesive property of the epoxy/phenoxy system to a certain extent.     

Birnessite和Cryptomelane型氧化锰的可控合成及其催化性能

以葡萄糖和高锰酸钾为原料,采用溶胶-凝胶法合成了birnessite(K_(1.35)MnO_2,简写为Bir)和cryptomelane(K_(0.27)MnO_2,简写为Cry)型氧化锰;采用X射线衍射、原子吸收光谱等考察了凝胶处理方法、反应物浓度比、焙烧温度和反应时间等对氧化锰晶型的影响.结果表明,采用不同方法处理凝胶可实现对Bir和Cry型氧化锰的可控合成.以不同的处理方法,葡萄糖和高锰酸钾的浓度比为O.74,反应20s制成凝胶,并在400℃焙烧2h,可分别制取高结晶度和高纯度的Bir和Cry型氧化锰.Bir和Cry型氧化锰在二甲醚燃烧反应中表现出优异的催化性能,且Cry型氧化锰的催化活性更高.     

在化学分析课程建设中构建多元化教研融合的教学模式培养高师创新人才*

化学分析是师范院校化学和化学教育专业学生的核心课程之一。在多年教学经验总结基础上,北京师范大学化学分析教学团队依托学院的教学资源、学科建设平台和学校教育教学改革项目,从教育理念、教学模式、课程考核、课程思政等角度出发,形成“多元化教研融合”的教育模式,建设培养高师创新人才的化学分析课程体系,逐步形成特色突出、切实可行、行之有效的创新人才培养模式。