Projectile fragment emission in the fragmentation of 56Fe on C,Al and CH2 targets at 471 A MeV

The emission angle and the transverse momentum distributions of projectile fragments produced in the fragmentation of 56Fe on CHs, C and A1 targets at 471 A MeV are measured. It is found that for the same target, the average value and width of the angular distribution decrease with an increase of the projectile fragment charge; for the same projectile fragment, the average value of the distribution increases and the width of the distribution decreases with increasing the target charge number. The transverse momentum distribution of a projectile fragment can be explained by a single Gaussian distribution and the averaged transverse momentum per nucleon decreases with the increase of the charge of projectile fragment. The cumulated squared transverse momentum distribution of a projectile fragment can be explained well by a single Rayleigh distribution. The temperature parameter of the emission source of the projectile fragment, calculated from the cumulated squared transverse momentum distribution, decreases with the increase of the size of the projectile fragment.     

高效液相色谱-质谱联用法测定烟草中茉莉酸

采用高效液相色谱-质谱(HPLC-MS)联用法检测烟草中茉莉酸(JA)含量。样品研磨均质后经丙酮和柠檬酸萃取,离心分离,取上清液,氮气吹去丙酮后用乙醚萃取。经氨丙基固相萃取柱净化,吹干后用色谱流动相溶解,过0.45μm有机滤膜。利用高效液相色谱-质谱联用电喷雾负离子,选择离子监测模式进行检测,内标法定量。结果表明,待测样品JA浓度范围在5～1 000ng/mL之间,标准曲线具有良好的线性关系。方法检出限(S/N≥3)是2.0ng/mL。平均回收率为80.6%～101.1%,相对标准偏差为3.5%～14.6%。应用该方法检测烟草打顶与不打顶植株之间JA含量的差异,结果比较理想。     

·OH自由基引发CH3SSCH3•+自由基裂解反应机理的理论研究

采用UωB97X-D/6-311+G^**方法, 研究了气相、 甲苯和水中OH自由基(·OH)引发CH₃SSCH₃自由基阳离子(CH₃SSC{\mathrm{H}}_{\mathrm{3}}^{?}⁺, DMDS^?+)裂解的反应机理, 并讨论了溶剂效应对反应的影响. 结果表明, ·OH和DMDS^·+首先形成自由基耦合产物CH₃S(OH)SCH₃⁺(R1)和氢提取产物复合物[CH₂=SSCH₃+H₂O]⁺(R2); 随后R1裂解直接发生 S—S键断裂协同质子转移, 而R2裂解依次发生构象变化、 C=S键亲碳加成和S—S键断裂协同质子转移. 去质子化的裂解产物为CH₃SOH, CH₂=S和HSCH₂OH. 甲苯略微降低了裂解反应速控步骤的自由能垒. 水溶剂有利于R1裂解, 但不利于R2裂解, 尤其是单个水分子参与反应. 在气相、 甲苯和水中, 以·OH和DMDS^·+为初始反应物, 虽然速控步骤的自由能垒为167.6~202.8 kJ/mol, 但裂解反应均是放热反应(?154.3~?31.4 kJ/mol).     

以D-樟脑酸与1,4-二（咪唑-1-基）丁烷为配体构筑的两个配位聚合物的结构与磁性

水热合成了2个以D-樟脑酸(D-H2cam)与1,4-二(咪唑-1-基)丁烷(1,4-bimb)为配体的配位聚合物:[Co(D-cam)(1,4-bimb)]n·4nH2O(1)和[Ni(D-cam)(1,4-bimb)]n(2)。通过X-射线单晶衍射,元素分析,红外光谱,XRD分析,热重,和磁性分析对其结构进行了表征。测定了这两个聚合物的磁性。结构分析表明,1为P2空间群,其链状结构由氢键作用连接形成二维结构;2为Pna21空间群,呈四重穿插的dia网络结构。     

Solution Blowing of Poly（dimethylsiloxane）/Nylon 6 Nanofiber Mats for Protective Applications

A new strategy was developed to fabricate superhydrophobic nylon 6 nanofibers, in which the blend solutions of poly(dimethylsiloxane)(PDMS) prepolymer and nylon 6 was spun using an innovative solution blowing process, and then the PDMS prepolymer contianning nanofibers were cured to obtain PDMS/nylon 6 nanofiber mats. Morphology, surface composition, non-wetting property and protective performance were investigated. The results showed that the addition of PDMS prepolymer improved the spinnability of the spinning solutions, and the PDMS/nylon 6 nanofibers had smooth surfaces and diameters from 100 nm to 350 nm. The presence of PDMS effectively enhanced the hydrophobicity of the nanofiber mats, showing water contact angles of 132° to 161° for PDMS contents of 1 wt% to 3 wt%. The PDMS/nylon 6 mats also possessed excellent protective and transport properties. The results indicated the potential application of the novel nanofiber mats in protective clothing.     

燃料电池用聚合物质子交换膜的研究进展

质子交换膜（PEM）是质子交换膜燃料电池的核心组件之一,具有隔绝阴阳极、提供质子传递通道和阻止燃料渗透的作用. 商业化应用的全氟磺酸PEM存在燃料渗透严重、高温条件下导电性差和成本高的问题,开发性能优良的聚合物PEM显得很有必要. 本文讨论了近年来聚合物PEM的研究进展,分别从聚合物的主链、支链和交联结构角度介绍了分子结构对薄膜相分离、质子导电性、稳定性和电池性能等性能的影响,并讨论了聚合物分子结构设计方面存在的问题,最后对燃料电池用聚合物PEM在未来的发展方向进行了展望.     

磁单极与磁洛伦兹力

概述了磁单极概念的历史发展,从洛伦兹变换出发,利用电磁场张量和四维力的协变性以及电荷相对论不变,直接证明了运动磁单极受磁洛伦兹力,建议了一个磁洛伦兹力的验证方案,并用磁洛伦兹力公式导出狄拉克电荷量子化条件．证明了磁洛伦兹力公式具有与库仑定律相同的精确度．     

聚(二甲基硅氧烷-co-甲氧基十二烷基硅氧烷)在棉纤维及其他模型表面的膜形貌及定向排列方式

用场发射扫描电镜(FESEM)、原子力显微镜(AFM)、光电子能谱(XPS)等仪器研究了棉纤维以及再生纤维素表面聚(二甲基硅氧烷-co-甲氧基十二烷基硅氧烷)(DDPS)的膜形貌及其定向排列方式.结果发现,在天然棉纤维以及再生纤维素模型表面,DDPS均能形成宏观上平滑、而微观形态学实则非均一的疏水性硅膜,表明DDPS的定向排列成膜方式为疏水性硅甲基、硅十二烷基朝外伸向空气,硅氧偶极键指向基质界面.     

离子液体中聚(3-溴噻吩)的电化学合成和电色效应研究

以1-丁基-3-甲基咪唑六氟磷酸盐离子液体[BMIM]PF₆既作为溶剂又作为支持电介质, 通过恒电流、循环伏安等方法制备聚(3-溴噻吩)(PBrT)膜. 采用红外光谱(FT-IR)和扫描电子显微镜(SEM)对PBrT膜的结构和形貌进行表征, 用热重和差热分析法(TG-DTA)研究聚合膜的热稳定性, 并利用紫外-可见光谱(UV-Vis)、计时电流和计时吸收曲线研究该聚合膜电化学和电致变色的特性. 研究结果表明, 与传统方法比较, 在离子液体[BMIM]PF₆中制备的PBrT膜更致密、光滑, 具有良好的氧化还原可逆性和充放电能力, 电活性高, 热稳定性好. 以该方法制备的PBrT膜颜色变化明显, 响应时间快(0.5 s), 同时由于离子液体具有电位窗宽、导电率高、可循环利用等优点, 因此在电化学聚合等方面具有良好的应用前景.     

MgSiO3状态方程的分子动力学模拟

The equation of state of MgSiO3 perovskite under high pressure and high temperature is simulated using the molecular dynamics method. It was found that the molecular dynamics simulation is very successful in accurately reproducing the measured molar volumes of MgSiO3 perovskite over a wide range of temperatures and pressures. The simulated equation of state of MgSiO3 perovskite matched experimental data at up to 140GPa at 300 K, as well as the fitting data of others and results from the first-principles simulation based on the local density approximation. The simulated equations of state of MgSiO3 perovskite at higher temperatures and higher pressures also correspond to the other calculations. In addition, the volume compression data of MgSiO3 perovskite is simulated up to 120 GPa at 300, 900, 2000 and 3000 K, respectively.