Synthesis of [60]Fullerene‐Fused Tetralones via Palladium‐ Catalyzed Ketone‐Directed sp2 C?H Activation and sp3 C?H Functionalization

The palladium‐catalyzed ketone‐directed dual sp² C H activation and sp³ C H functionalization has been applied for fullerene functionalization for the first time. The sec‐alkyl aryl ketones have been exploited to react with [60]fullerene (C₆₀) to provide the novel and scarce C₆₀‐fused tetralones. The combined use of a highly active cationic palladium(II) catalyst and trifluoromethanesulfonic acid is crucial for the improvement of the reaction yield. A plausible reaction mechanism leading to the observed products has been proposed, and the electrochemistry of the fullerene products has also been investigated.

     

Direct Decarboxylative Alkynylation of α,α‐Difluoroarylacetic Acids under Transition Metal‐Free Conditions

An efficient and generally applicable protocol for decarboxylative coupling of α,α‐difluoroarylacetic acids with ethynylbenziodoxolone (EBX) reagents has been developed, affording α,α‐difluoromethylated alkynes bearing various functional groups in moderate to excellent yields. Remarkably, this potassium persulfate (K₂S₂O₈)‐promoted reaction employs water as solvent under transition metal‐free conditions, thus providing a green synthetic approach to α,α‐difluoromethylated alkynes.

     

Palladium‐Catalyzed Carbonylative Synthesis of 2,3‐Disubstituted Chromones

An unexpected palladium‐catalyzed carbonylative synthesis of 2,3‐disubstituted chromones has been developed. Starting from 2‐bromofluorobenzenes and ketones, the corresponding chromones were produced in good yields. By control experiments, this transformation was found to proceed through a sequential carbonylation/Claisen–Hasse rearrangement/intramolecular nucleophilic aromatic substitution approach (S_NAr). More specifically, the reaction sequence started with a palladium‐catalyzed carbonylation of the ketone with o‐bromofluorobenzene to give the vinyl benzoates, which subsequently transformed into 1,3‐diketones via a Claisen–Hasse rearrangement. The final products were produced after an intramolecular S_NAr reaction of the in situ formed 1,3‐diketone.

     

Probabilistic analysis of site-specific load-displacement behaviour of cement-fly ash-gravel piles

Cement-fly ash-gravel (CFG) piles comprise one of the novel ground-improvement methods. They are attracting considerable attention, as their beneficial role in accessible soft foundations is being increasingly exploited by the surging urban industrial development in China. Despite their recognised significance, however, the load-settlement behaviour of CFG piles is poorly understood, particularly in the context of probabilistic assessments. This study focuses on six full-scale CFG pile load test datasets, consisting of 245 samples collected at six sites in the Beijing region, under static axial compression loading. As a part of this investigation, a regression curve is applied to the load-settlement data for each load test in the database using a two-parametric hyperbolic or power law curve-fitting equation. Moreover, an assessment of the multiple load-displacement curves, based on the full set of pile load measurements conducted at a particular test site, reveals that the scatter observed in the regression parameter values is mainly caused by the inherent soil variability.Thus, a bivariate copula-based mixed distribution is chosen to represent the dependence between these regression parameters. A simple copula-based simulation model is used to estimate the reliability index at any specific allowable settlement for the serviceability limit state (SLS) design. The correlation coefficients in the copula-based distributions of the regression parameters are proven to have an impact on the reliability index of this pile foundation. A scatter analysis of the load-displacement behaviour provides insight into the probabilistic design of site-specific CFG pile foundations.     

日本养老政策发展及其对中国的启发与借鉴

着眼于探讨日本养老政策变迁下,养老环境的现状特点与不断发展的基本诱因,以及既定政策与客观实践之间共同发展与相互促进的关系。首先,从对日本快速老龄化背景下相关的法律法规、政策规范的整理分析入手,探讨了其产生、发展、变革、融合的经年变化趋势。其次,聚焦了从“品质提升期”到“医养融合发展期”的发展阶段下养老环境建设的三大主要特点：（1）居住空间的适老化改造;（2）机构养老的生活化转变;（3）“地域护理包括支援体系”（the Integrated Community Care System）建设。最后,结合我国老龄化背景下的政策发展核心趋势,探索未来中国养老环境的建设模式,为中国养老建筑与环境的发展提供参考与借鉴。     

胜利油田稠油热采开发技术研究进展

针对胜利油田稠油油藏地质特点及开发难点,重点介绍了中深层特超稠油油藏、浅薄层超稠油油藏、敏感性稠油油藏和低渗透稠油油藏等复杂稠油油藏的开发技术,并对其提高采收率机理和现场应用效果进行了总结概括。在此基础上,根据目前研究进展指出了稠油热采开发技术的发展方向,重点介绍了超深层低渗稠油和浅薄层特超稠油的开发技术及其应用。     

Cavitation in hard/soft/hard three-layer core-shell structural rubber particles

The microvoiding mechanisms and mechanical properties of blends of poly(viny1chloride)(PVC) with hard/soft/hard three-layer core-shell structural particles polystyrene/polybutadiene/polymethylmethacrylate (PSBM) are investigated. The core-shell particles ranging from 110 to 182 nm to 254 nm. Toughened blends with higher tensile strength are obtained, which is related to the presence of hard polystyrene glassy domains in the core acting as stiffening agents. Cavitation occurs in all size rubber, relieves the triaxial tension and thereby promotes shear yielding of the PVC matrix. The three layer structure of the particles provides multi- interface, which act as trigger of cavitation. Furthermore, cavitiation in the blend containing small particles (110 nm) is observed due to its higher tensile stress, under which the cavitation process can be completed.     

Deuterium Tracer Studies and Gas Chromatography–Mass Spectrometry Analysis of Deuterated Products during Fischer–Tropsch Synthesis

Hydrogen is one of the two reagents of Fischer–Tropsch (FT) synthesis. In order to have the information about the role of hydrogen, which is the key to understand the mechanism of the reaction, deuterium tracer experiments are useful. One of the obstacles in conducting deuterium tracer experiments during FT reactions is to accurately determine the amounts of isotopomers of a hydrocarbon in the FT products. Because of an inverse isotope effect for isotopomers on a GC column, the isotopomer with more deuterium atoms will be eluted first. If the difference in deuterium atoms is >3, the quantitative analysis of a mixture of isotopomers can be conducted using GC–FID. However, if the difference in deuterium atoms is <3, an accurate measurement of the relative amounts of isotopomers of a compound requires a determination of the total area of all of the molecular ions by gas chromatography–mass spectrometry (GC–MS). The results determined using this method are close to the true value (by weight) with an error of ±3 %. The deuterium tracer technique and GC–MS analysis of FT products have been used to study the accumulation effects, the role of H₂O, the isotope effect, the role of C₂ species derived from ethanol and ethene, and deuterium enrichment during FT reactions.     

Photo-induced controlled/living copolymerization of styrene and acrylic acid and determination of reactivity ratios

A controlled/living photopolymerization of styrene (St) and acrylic acid (AA) mediated by FeCl₃·6H₂O/tetramethylethylenediamine (TMEDA) was performed in N,N-dimethylformamide using 4-bromomethylbenzophenon (4-BMBP) as photoinitiator at room temperature under UV irradiation. 4-BMBP was first used as ATRP initiator and photoinitiator. A well-defined poly(styrene-co-acrylic acid) with predetermined molecular weight and narrow molecular weight distribution was obtained. The kinetic rule of controlled free radical photopolymerization of St and AA was studied. The kinetic results showed that the obtained random poly(St-co-AA) copolymers produced narrow polydispersity (PDI) within the range of 1.25–1.32 when the conversion was beyond 16.5 %, which was characterized by GPC. The plots of number average molecular weight versus conversion and ln([M]₀/[M]) versus time were linear, indicating a controlled/living photopolymerization process. The system proceeded under mild and environmentally friendly conditions. The effects of initiator, catalyst, ligand, and vitamin C(VC) concentrations on polymerization process were investigated. The copolymers were characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹H NMR). The methods of Mayo-Lewis (ML), Kelen-Tudos (KT), and Yzrielev-Brokhina Roskin (YBR) were used to calculate the monomer reactivity ratios of controlled/living photopolymerization of St and AA at low conversions under selected conditions. The monomer reactivity ratios of St and AA were calculated to be r _St = 0.82 and r _AA = 0.30, respectively in this system. The living characteristics were demonstrated by chain extension experiment.