山西省古建筑消防安全工作存在的问题及对策

通过对专项治理发现的古建筑消防安全工作存在的问题的研究 ,提出了解决这些问题的建议     

Kinetic modeling of simultaneous polycondensation and free radical polymerization for polyurethane/poly(methyl methacrylate) interpenetrating polymer network

A comprehensive kinetic Monte Carlo algorithm has been developed to investigate the formation process of a polyurethane/poly(methyl methacrylate) (PU/PMMA) interpenetrating polymer network (IPN), in which a component independent strategy is proposed to perform the simulation of simultaneous polycondensation and free radical polymerization. An empiric diffusion model based on the mass fraction of polymer is used to quantify the effect of diffusional limitations on MMA polymerization. Results show that the presence of acrylic monomers has little impact on the formation rate of PU, but the presence of the PU network can accelerate the polymerization of MMA. In addition, the effects of component mass ratio, acrylic cross-linker concentration, and [NCO]/[OH] ratio on the IPN formation kinetics are investigated based on the kinetic model. It is believed that the as-developed modeling strategy can be extended to other IPN systems and provide a better understanding of the interactions between chemically independent networks.     

管井降水技术在多种含水介质基坑工程中的应用

结合蚌埠城市中心广场会展中心工程，介绍了管井降水技术在多种含水介质的复杂地质环境下的应用。     

A New Ferroelectric Phase of YMnO3 Induced by Oxygen‐Vacancy Ordering

Manganese oxides are good candidates of strongly correlated electron materials due to the uniqueness of electronic structure of manganese and the mobility of oxygen among lattice sites under external impacts. Here, we used electron beam as the excitation source to explore the structural evolution of YMnO₃ and identified a new phase under the radiation of electron beam in the transmission electron microscope. Analyses of the electron energy‐loss spectra reveal that this phase originates from ordered oxygen vacancy. We applied the first principles calculation to pick out the optimized stable structure with a lower polarization, and verified its correctness by electron diffraction and image simulations. Analyses of density of states indicate that weak Y–O covalence is favorable for the existence of ferroelectricity, supporting the electrostatic nature of ferroelectricity in the YMnO₃.     

A physical strategy for the preparation of isotactic polypropylene spheres with microsphere and bead–string spherulite morphologies

This study mainly focuses on the formation of isotactic polypropylene (iPP) blend morphologies with microspheres and distinct bead–string spherulites. iPP microspheres have been prepared by a simple and convenient strategy through either an isothermal or a nonisothermal crystallization process based on the macrophase‐separated structure in molten state of iPP/olefin block copolymer (OBC) blend. The dimension of the iPP spheres can be adjusted easily from about 1 µm to >10 µm by controlling the compatibility and annealing conditions. It was found that any of the following three parameters, the molecular structure of OBC (particularly the octene content), molecular weight of iPP, and annealing condition can be rescaled with others in controlling the dimension of the iPP microspheres. The mechanism of the formation of iPP microspheres was studied in detail. Surprisingly, the typical spinodal decomposition morphology with interconnected or thin sheet structure is the precursor of these microspheres. During the subsequent annealing process, it breaks up and further coarsens into spherical structure. In addition, distinct spherulites with a bead–string substructure have been obtained during the isothermal crystallization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40863.     

Thermal degradation behavior and gas phase flame‐retardant mechanism of polylactide/PCPP blends

The thermal degradation behavior of the blend based on polylactide (PLA) and poly(1,2‐propanediol 2‐carboxyethyl phenyl phosphinate) (PCPP) was investigated by the thermogravimetric analysis (TGA). Thermal degradation activation energies (E_a) of neat PLA and PLA/15% PCPP blend were calculated via the Flynn–Wall–Ozawa method. The E_a of the blends increased with the addition of PCPP increasing when the conversion was higher than 10%. In addition, the appropriate conversion models for the thermal degradation process of PLA and PLA/15% PCPP were studied via the Criado method. At the same time, the main gaseous decomposition products of PLA and its blend were identified by TGA/infrared spectrometry (TGA–FTIR) analysis. And it revealed that the PCPP improved the flame‐retardant property of PLA via altering the release of the flammable gas and nonflammable gas. Moreover, the PCPP improved the flame‐retardant property of PLA by inhibiting exothermic oxidation reactions in the combustion, which was further proved by pyrolysis–gas chromatography–mass spectrometry analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40480.     

除草剂吡草胺的合成

以2,6-二甲基苯胺为原料,与多聚甲醛经亲核消除反应生成希夫碱,再与氯乙酰氯加成反应,最后与吡唑缩合转晶得到除草剂原药吡草胺三斜晶形,总收率达71.5%(以2,6-二甲基苯胺计),含量大于97%,该工艺方法简便、易行,具有工业化应用前景。     

Visible Light‐Initiated C(sp3)?Br/C(sp3)?H Functionalization of α‐Carbonyl Alkyl Bromides through Hydride Radical Shift

A new visible light‐initiated 1,5‐hydride radical shift strategy has been developed to enable the one‐step functionalization of both a C(sp³) Br bond and a C(sp³) H bond adjacent to the same carbon atom. This visible light photoredox catalysis offers a mild and straightforward access to diverse five‐membered carbocyclic ring‐fused polycyclic hydrocarbons with high turnover numbers (TONs; up to 4.93×10³) and broad substrate scope.

     

Efficient Catalyst for Both Suzuki and Heck Cross‐Coupling Reactions: Synthesis and Catalytic Behaviour of Geometry‐ Constrained Iminopyridylpalladium Chlorides

A series of geometry‐constrained iminopyridyl‐palladium chlorides were synthesized and characterized. These phosphine‐free palladium complexes were explored for their catalytic activities in both Suzuki and Heck cross‐coupling reactions, achieving turnover numbers as high as 10⁶ towards various aryl bromides, even those containing various functionalities. In addition, the influence of substituents with steric and electronic factors was reflected by the differences observed in their activities.