Mn12-Ac磁性分子团簇单晶的热重-差热分析与结构转变

通过热重-差热分析(TG-DTA)，考察了Mn12-Ac磁性分子晶体从室温到270℃的热失重过程.结合x射线粉末衍射分析，认为在第一个失重阶段，即25—110℃，Mn12-Ac失去了处于团簇分子间隙的结晶乙酸和结晶水，同时失去了团簇分子中与4个Mn3+配位的4个H2O，Mn12-Ac单晶结构被破坏，但是团簇分子的基本结构依然存在；在第二个失重阶段，即180—230℃，Mn12-Ac转变为γ-Mn2O3，其中混有少量Mn3O4. 关键词： Mn12 分子团簇 热重-差热分析 x射线衍射     

Existence results for second-order system with impulse effects via variational methods

In this paper, we investigate the positive solutions of a second-order system with impulse effects. By using critical point theory the existence result of positive solutions is obtained.     

Predicting hiCE inhibitors based upon pharmacophore models derived from the receptor and its ligands

Human intestinal carboxyl esterase (hiCE) is a drug target for ameliorating irinotecan-induced diarrhea. By reducing irinotecan-induced diarrhea, hiCE inhibitors can improve the anti-cancer efficacy of irinotecan. To find effective hiCE inhibitors, a new virtual screening protocol that combines pharmacophore models derived from the hiCE structure and its ligands has been proposed. The hiCE structure has been constructed through homology techniques using hCES1’s crystal structure. The hiCE structure was optimized via molecular dynamics simulations with the most known active hiCE inhibitors docked into the structure. An optimized pharmacophore, derived from the receptor, was then generated. A ligand-based pharmacophore was also generated from a larger set of known hiCE inhibitors. The final hiCE inhibitor predictions were based upon the virtual screening hits from both ligand-based and receptor-based pharmacophore models. The hit rates from the ligand-based and receptor-based pharmacophore models are 88% and 86%, respectively. The final hit rate is 94%. The two models are highly consistent with one another (85%). This proves that both models are reliable.     

Optimal Groomings with Grooming Ratios Six and Seven

Grooming uniform all‐to‐all traffic in optical (SONET) rings with grooming ratio C requires the determination of a decomposition of the complete graph into subgraphs each having at most C edges. The drop cost of such a grooming is the total number of vertices of nonzero degree in these subgraphs, and the grooming is optimal when the drop cost is minimum. The determination of optimal C‐groomings has been considered for , and completely solved for . For , it has been shown that the lower bound for the drop cost of an optimal C‐grooming can be attained for almost all orders with 5 exceptions and 308 possible exceptions. For , there are infinitely many unsettled orders; especially the case is far from complete. In this paper, we show that the lower bound for the drop cost of a 6‐grooming can be attained for almost all orders by reducing the 308 possible exceptions to 3, and that the lower bound for the drop cost of a 7‐grooming can be attained for almost all orders with seven exceptions and 16 possible exceptions. Moreover, for the unsettled orders, we give upper bounds for the minimum drop costs.     

Self-calibration method for cerium-doped lanthanum bromide scintillator detector in the 0.1–2.0 MeV energy range

In recent years, the cerium-doped lanthanum bromide, LaBr₃ (Ce = 5 %) detector is increasingly playing an important role in radiation measurements because of its higher energy resolution (~3 % at 662 keV), faster luminescence decay time (~35 ns) and higher detection efficiency compared to 7.65 cm × 7.65 cm NaI(Tl) detector. Intrinsic spectra between 1,800 and 3,000 keV derived from internal radioactivity within LaBr₃(Ce) scintillators have been investigated in some literatures, and these results are confirmed by the experiments in this work. In this paper, a new method for LaBr₃(Ce) detector energy calibration from 100 to 2,000 keV is proposed using the intrinsic spectra (self-calibration) instead of the standard gamma sources. Proof-of-concept experiment results show that self-calibration can guarantee energy accuracy of better than 0.815 % and can be applied outside the laboratory. The stability and applicability of this method are also investigated systematically.     

Imaging intrinsic diffusion of bridge-bonded oxygen vacancies on TiO2(110)

We report the first measurements and calculations of the intrinsic mobility of bridge-bonded oxygen (BBO) vacancies on a rutile TiO2(110). The sequences of isothermal (340-420 K) scanning tunneling microscope images show that BBO vacancies migrate along BBO rows. The hopping rate increases exponentially with increasing temperature with an experimental activation energy of 1.15 eV. Density functional theory calculations are in very good agreement giving an energy barrier for hopping of 1.03 eV. Both theory and experiment indicate repulsive interactions between vacancies on a given BBO row.     

In situ synthesis of CdS/ZnS composite nanoparticles from ZIF-8 for visible light disposal of Cr(VI)

Journal of Sol-Gel Science and Technology - Zeolitic Imidazolate Framework (ZIF-8) micropolyhedra were employed as a raw material for the synthesis of fine cadmium sulfide/zinc sulfide (CdS/ZnS)...     

辐射接枝法制备膨化聚四氟乙烯杂化膜及其抗菌性表征

通过共辐射接枝的方法,将聚丙烯酸成功接枝到膨化聚四氟乙烯薄膜上. 采用NaBH₄还原吸附在接枝链上的银离子,在膜中原位负载银纳米粒子,制备了抗菌性ePTFE杂化膜. 杂化膜的SEM、XPS、XRD和TGA表征结果表明,负载的银纳米粒子粒径为几十纳米至100 nm. 而银纳米粒子的负载量可由聚丙烯酸的接枝率控制. 细菌平板计数法测试结果证明,所制备的杂化膜具有优异的抗菌性,对大肠杆菌的抗菌率高达100%.