Fixation of carbon dioxide into aliphatic polycarbonate,cobalt porphyrin catalyzed regio‐specific poly(propylene carbonate) with high molecular weight

Cobalt porphyrin complex (TPPCo^IIIX) (TPP = 5, 10, 15, 20‐Tetraphenyl‐ porphyrin; X = halide) in combination with ionic organic ammonium salt was used for the regio‐specific copolymerization of propylene oxide and carbon dioxide. A turnover frequency of 188 h^?1 was achieved after 5 h, and the byproduct propylene carbonate was successfully controlled to below 1%, where the obtained poly(propylene carbonate) (PPC) showed number average molecular weight (M_n) of 48 kg/mol, head‐to‐tail content of 93%, and carbonate linkage of over 99%. When the polymerization time was prolonged to 24 h, PPC with M_n over 115 kg/mol and head‐to‐tail linkage maintaining 90% was prepared, whose glass transition temperature reached 44.5 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5959–5967, 2008     

n—型聚乙炔复合膜电极性能的研究

自MacDiarmid等将聚乙炔(PA)做为二次电池的电极材料以来,其电化学特性和行为引起了人们的极大兴趣.随后的研究表明,p-型PA[(CH)~(y )Ay~-]_x在电解液中不稳定,用ClO_4~-掺杂的PA充放循环时有降解发生.n-型PA[My~ (CH)~(y-)]_x(y≤0.10)在THF/LiClO_4电解质中较稳定,电化学还原完全可逆,目前已实现1100次充放循环.因此,它既可做电池的正极材料(碱金属为负极),又可做负极材料(TiS_2为正极).我们发现     

Congruences on abundant semigroups associated with Green’s *-relations

Good congruences are defined as congruences preserving \(\mathcal L^*\)-classes and \(\mathcal R^*\)-classes. In this paper the good congruences on abundant semigroups generated by Green’s \(*\)-relations are investigated. The related results for regular semigroups are enriched and extended.     

<Superscript>99m</Superscript>Tc(CO)<Subscript>3</Subscript>–AOPA colchicine conjugate as a potential tumor imaging agent

This work reports the synthesis, radiolabeling and preliminary biodistribution results in tumor-bearing mice of the ^99mTc(CO)₃–AOPA colchicine conjugate. The novel ligand was successfully synthesized by conjugation of N-(acetyloxy)-2-picolylamino (AOPA) to deacetylcolchicine via a short carbonyl-methylene linker. Radiolabeling was performed in high yield with [^99mTc(CO)₃]⁺ core. ^99mTc(CO)₃–AOPA colchicine conjugate was hydrophilic and was stable at room temperature. Biodistribution studies in tumor-bearing mice showed that ^99mTc(CO)₃–AOPA colchicine conjugate accumulated in the tumor with good uptake and retention. However, its clearance from normal organs was not so fast, resulting in poor T/NT ratios. Further modification on the linker or/and ^99mTc-chelate to improve the tumor targeting efficacy and in vivo kinetic profiles is currently in progress.     

氨酯化合物对聚碳酸1,2-丙二酯的同时增韧和增强研究

采用非异氰酸酯路线合成了1,6-六亚甲基二氨基甲酸羟异丙酯(BPU),分子量为320.利用熔融共混方法制备了聚碳酸1,2-丙二酯(PPC)/BPU共混物.研究发现BPU与PPC间有较好的相容性,随着BPU含量的增加,共混体系的起始热分解温度(Td.5％)可分别增加24～33℃,共混物韧性也显著提高,断裂伸长率最大可增至...     

Crosslinkable poly(propylene carbonate): High‐yield synthesis and performance improvement

A crosslinking strategy was used to improve the thermal and mechanical performance of poly(propylene carbonate) (PPC): PPC bearing a small moiety of pendant C?C groups was synthesized by the terpolymerization of allyl glycidyl ether (AGE), propylene oxide (PO), and carbon dioxide (CO₂). Almost no yield loss was found in comparison with that of the PO and CO₂ copolymer when the concentration of AGE units in the terpolymer was less than 5 mol %. Once subjected to UV‐radiation crosslinking, the crosslinked PPC film showed an elastic modulus 1 order of magnitude higher than that of the uncrosslinked one. Moreover, crosslinked PPC showed hot‐set elongation at 65 °C of 17.2% and permanent deformation approaching 0, whereas they were 35.3 and 17.2% for uncrosslinked PPC, respectively. Therefore, the PPC application window was enlarged to a higher temperature zone by the crosslinking strategy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5329–5336, 2006     

Room temperature conductance switching in a molecular iron(iii) spin crossover junction

Herein, we report the first room temperature switchable Fe(iii) molecular spin crossover (SCO) tunnel junction. The junction is constructed from [Fe^III(qsal-I)₂]NTf₂ (qsal-I = 4-iodo-2-[(8-quinolylimino)methyl]phenolate) molecules self-assembled on graphene surfaces with conductance switching of one order of magnitude associated with the high and low spin states of the SCO complex. Normalized conductance analysis of the current–voltage characteristics as a function of temperature reveals that charge transport across the SCO molecule is dominated by coherent tunnelling. Temperature-dependent X-ray absorption spectroscopy and density functional theory confirm the SCO complex retains its SCO functionality on the surface implying that van der Waals molecule—electrode interfaces provide a good trade-off between junction stability while retaining SCO switching capability. These results provide new insights and may aid in the design of other types of molecular devices based on SCO compounds.

Herein, we report the first room temperature switchable Fe(iii) molecular spin crossover (SCO) tunnel junction.     

一种新型的固着磨料抛光片──WBN抛光片的制作工艺及其特性

本文描述了用冲击合成方法得到的超硬材料纤锌矿型氮化硼（ＷＢＮ）制作的一种新型抛光片。在光学玻璃抛光中的初步应用显示：这种新型的ＷＢＮ抛光片具有比传统的ＣｅＯ２。抛光片更大的切削力、更短的抛光时间和更好的表面粗糙度及更长寿命等优点。     

Super rpp semigroups

We study a class of special strongly rpp semigroups, namely, the class of super rpp semigroups. These super rpp semigroups are generalizations of both superabundant semigroups and Clifford semigroups within the class of rpp semigroups. In particular, we prove that a super rpp semigroup is a semilattice of D ^(l)-simple strongly rpp semigroups. Our result not only generalizes a well-known theorem of Clifford in the class of completely regular semigroups but also strengthens some structure theorems obtained by Ren-Shum for superabundant semigroups which are orthodox. Some special super rpp semigroups are considered and discussed.