Studies on the Phase Properties of Winsor Ⅰ-Ⅲ Type Microemulsions with Dielectric Relaxation Spectroscopy

The dielectric relaxation spectroscopy （DRS） of Winsor I -Ⅲ microemulsions for nonionic surfactant octyl polyglucoside CsG1.46/1-butanol/cyclohexanedwater system was studied. The experiment shows that the permittivity decreases with the increase in the frequency and clear dielectric relaxation phenomena were observed. Permittivity obviously decreases with the change of the microstructure of the microemulsion, W/O, B.C. and O/W can be distinguished by the permittivity.     

顶空固相微萃取-气相色谱-质谱法测定废水中痕量挥发性烷基硫化物

建立了顶空固相微萃取(HS-SPME)和气相色谱/质谱(GC/MS)联用测定人工湿地废水中的痕量挥发性烷基硫化物的方法。针对废水中两种主要的挥发性烷基硫化物(二甲基硫、二甲基二硫),详细研究了萃取纤维头的种类、萃取时间、萃取温度、pH值、离子强度、样品量及解析条件对HS-SPME的影响。载气为高纯氦气,流速为1.0mL/min,色谱柱为DB-5ms毛细管柱(0.25μm,30m×0.32mm),柱温:25℃(5min)■40℃(1min)■60℃(5min);在优化的实验条件下,本法测定二甲基硫及二甲基二硫的线性范围分别为10～10000ng/L和1～10000ng/L;检出限(3σ)分别为1.9ng/L和1.8ng/L;相对标准偏差小于10%;回收率分别为81.0%～94.6%和84.0%～100.9%。用二乙基硫为内标物质,将本法用于人工湿地废水中主要的烷基硫化物二甲基硫和二甲基二硫的测定,获得满意结果。     

Controlled release of drugs from CD polymers substituted with ionic groups

Various disinfecting drugs (ethacridine lactate, methylene blue, gentian violet, brilliant green, fuchsin acid, cetylpyridinium chloride) were incorporated into CD bead polymers substituted with carboxymetbyl groups and a retarded release rate was measured. These polymers were successfully used as sustained release wound powders as well as in chewing gum formulations.     

RNA Methylation m6A: A New Code and Drug Target?

The m⁶A‐RNA modification is a dynamic and reversible process, which has emerged as a new RNA code for the regulation of gene expression. The functional network of methyltransferases (writers), demethylases (erasers), and binding proteins (readers) modulate the level of m⁶A modification. Dysfunction of RNA methylation has been associated with various fundamental biological processes and human diseases. Herein, we briefly introduce an understanding‐enabled manipulation on m⁶A‐RNA modification with an emphasis on the use of small‐molecule intervention.      

Enhancement of three-photon absorption cross-sections in a novel class of symmetrical charge transfer fluorene-based molecules

The three-photon absorption effect (3PA) of two novel symmetrical charge transfer fluorene-based molecules (abbreviated as BASF and BMOSF) has been determined by using a Q-switched Nd:YAG laser pumped with 38 ps pulses at 1064 nm in DMF. The measured 3PA cross-sections are 84 × 10⁻⁷⁸ and 114 × 10⁻⁷⁸ cm⁶ s², respectively. The geometries and electronic excitations of these two molecules are systematically studied by PM3 and ZINDO/S methods. The relationships between 3PA cross-sections and intramolecular charge transfer are discussed micromechanically. The experimental and theoretical results have shown that the larger intramolecular charge transfer, which was characterized by the charge density difference between the ground state (S₀) and the first excited state (S₁), the greater enhancement of the 3PA cross-sections.     

Linear scaling computation of the Fock matrix. VII. Parallel computation of the Coulomb matrix

We present parallelization of a quantum-chemical tree-code for linear scaling computation of the Coulomb matrix. Equal time partition is used to load balance computation of the Coulomb matrix. Equal time partition is a measurement based algorithm for domain decomposition that exploits small variation of the density between self-consistent-field cycles to achieve load balance. Efficiency of the equal time partition is illustrated by several tests involving both finite and periodic systems. It is found that equal time partition is able to deliver 91%-98% efficiency with 128 processors in the most time consuming part of the Coulomb matrix calculation. The current parallel quantum chemical tree code is able to deliver 63%-81% overall efficiency on 128 processors with fine grained parallelism (less than two heavy atoms per processor).     

Preparation and characterization of poly(propylene carbonate)/montmorillonite nanocomposites by solution intercalation

Poly(propylene carbonate) (PPC) is a new biodegradable aliphatic polycarbonate. However, the poor thermal stability and low glass transition temperatures (T_g) have limited its applications. To improve the thermal properties of PPC, organophilic montmorillonite (OMMT) was mixed with PPC by a solution intercalation method to produce nanocomposites. An intercalated-and-flocculated structure of PPC/OMMT nanocomposites was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal and mechanical properties of PPC/OMMT nanocomposites were investigated by thermal gravimetric analysis (TGA), differential scanning calorimetric (DSC), and electronic tensile tester. Due to the nanometer-sized dispersion of layered silicate in polymer matrix, PPC/OMMT nanocomposites exhibit improved thermal and mechanical properties than pure PPC. When the OMMT content is 4 wt%, the PPC/OMMT nanocomposite shows the best thermal and mechanical properties. These results indicate that nanocomposition is an efficient and convenient method to improve the properties of PPC.     

Physical and electrochemical characterizations of microwave-assisted polyol preparation of carbon-supported PtRu nanoparticles

PtRu nanoparticles supported on Vulcan XC-72 carbon and carbon nanotubes were prepared by a microwave-assisted polyol process. The catalysts were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The PtRu nanoparticles, which were uniformly dispersed on carbon, were 2-6 nm in diameter. All PtRu/C catalysts prepared as such displayed the characteristic diffraction peaks of a Pt face-centered cubic structure, excepting that the 2theta values were shifted to slightly higher values. XPS analysis revealed that the catalysts contained mostly Pt(0) and Ru(0), with traces of Pt(II), Pt(IV), and Ru(IV). The electro-oxidation of methanol was studied by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. It was found that both PtRu/C catalysts had high and more durable electrocatalytic activities for methanol oxidation than a comparative Pt/C catalyst. Preliminary data from a direct methanol fuel cell single stack test cell using the Vulcan-carbon-supported PtRu alloy as the anode catalyst showed high power density.     

新型四硫代富瓦烯衍生物的合成及其性质的研究

合成了3个新的含有卤素取代基的四硫代富瓦烯衍生物及6个新的相关化合物。利用溶液的电子吸收光谱对四硫代富瓦烯衍生物的性质进行了研究。研究结果表明, 四硫代富瓦烯衍生物的分子中π轨道之间的能级差较小, 因而分子具有较高的稳定性。     

Polymerization-induced viscoelastic phase separation in polyethersulfone-modified epoxy systems

The polymerization-induced phase-separation process of polyethersulfone (PES)-modified epoxy systems was monitored in situ continuously on a single sample throughout the entire curing process by using optical microscopes, time-resolved light scattering (TRLS), scanning electronic microscopes (SEM), and a rheometry instrument. At specific PES content a viscoelastic transformation process of phase inversion morphology to bicontinuous was found with an optical microscope. The rheological behavior during phase separation corresponds well with the morphology development. Light-scattering results monitoring the phase-separation process of systems with final phase inversion morphology show a typical exponential decay procedure of scattering vector qm. The characteristic relaxation time of phase separation can be described well by the WLF equation.