纳米钯催化苄基氯代物与烯丙基硼酸频哪醇酯的羧化Suzuki偶联反应（英文）

CO_2是廉价的Cl源,同时具有无毒、储量丰富的优点,符合绿色化学发展要求.利用CO_2构筑新的C-C键是化学固定CO_2的重要方法.β,γ-不饱和酯类结构单元是许多生物活性分子的重要组成部分,经由双π-烯丙基钯中间体与CO_2反应,合成新的β,γ-不饱和酯类化合物,具有重要意义.CO_2与有机硼化合物的羧化反应己有报道,有机硼化合物具有低毒、对水不敏感等优点.但是己报道的羧化Suzuki偶联反应存在诸多缺点:(1)需要使用含膦或者氮杂环卡宾配体的催化剂,而这些催化剂的制备过程使前期实验步骤变得冗长,同时反应液的酸化后处理过程也会造成环境污染;(2)有机硼试剂的官能团兼容范围窄,限制了底物范围的拓展.本课题组以原位生成的纳米钯粒子为催化剂,在CO_2存在的温和条件下,高效实现了苄氯与烯丙基硼酸频哪醇酯的羧化Suzuki偶联反应.反应过程中无其它配体加入,反应结束后不需要酸化或酯化的后处理过程.该反应将具有广泛的官能团兼容性.本文以TBAB稳定的纳米钯粒子为催化剂,在温和条件下,实现了氯甲基芳香化合物、烯丙基硼酸频哪醇酯和CO_2的三组分羧化Suzuki偶联反应.最佳反应条件为:Pd(acac)_2(5mol%)、TBAB(0.7mmol,1.4 equiv.)、KF(1mmol,2.0 equiv.)、苄基卤代物(0.5 mmol)、烯丙基硼酸频哪醇酯(0.6 mmol,1.2 equiv.)、CO_2(2.0 MPa)、溶剂THF(5 mL),50℃反应24h.在最佳反应条件下,苯环、萘环以及杂芳环的氯甲基化合物均可发生该羧化反应.苯环上取代基的位置对产物的收率有影响.当使用1-溴甲基萘作为底物时反应也能够发生,收率与1-氯甲基萘作为底物时的收率相当.与已报道有机硼试剂的羧化反应相比,该反应体系无需加入配体,原位生成了纳米钯粒子,避免了催化剂或者配体的复杂制备过程.该反应中,氟离子的存在是必要的,对烯丙基硼酸频哪醇酯具有活化作用.

Long-Term Preservation of Electronic Record Based on Digital Continuity in Smart Cities

Under the co-promotion of the wave of urbanization and the rise of data science,smart cities have become the new concept and new practice of urban development.Smart cities are the combination of information technology represented by the Internet of Things,cloud computing,mobile networks and big data,and urbanization.How to effectively achieve the long-term preservation of massive,heterogeneous,and multi-source digital electronic records in smart cities is a key issue thatmust be solved.Digital continuity can ensure the accessibility,integrity and availability of information.The quality management of electronic record,like the quality management of product,will run through every phase of the urban lifecycle.Based on data quality management,this paper constructs digital continuity of smart city electronic records.Furthermore,thework in this paper ensures the authenticity,integrity,availability and timeliness of electronic documents by quality management of electronic record.This paper elaborates on the overall technical architecture of electronic record,as well as the various technical means needed to protect its four characteristics.

Front-end Control Mechanism of Electronic Records

In the digital era,how to ensure the authenticity and integrity of elec-tronic records has become an open challenging issue.Front-end control is an important concept as well as a basic principle in electronic record management.Under the instruction of front-end control,many original management links in the record-management stage are required to move forward,and the managers enter the formation stage of the electronic records to ensure the originality.How-ever,the front-end control technique primarily focuses on transaction manage-ment,and it lacks the strategy of providing the control of electronic records.In this paper,a novel electronic record front-end control mechanism is proposed by adopting proxy re-encryption and requiring archivists to participate in the man-agement of electronic records before the record is created to solve the problem.Specifically,when an electronic record is generated,the proposed mechanism interacts with the producer of the electronic record to generate a corresponding encryption key.Moreover,electronic records are encrypted by the key to protect their confidentiality,which can prevent the leakage of electronic record informa-tion.In addition,when transferring the electronic record,archivists use proxy re-encryption technology to convert electronic records,allowing management by an archivist,ensuring their originality and authenticity.

消费地原则在B2B跨境转让服务或无形资产中的应用

经济全球化和经济数字化使各国的税收制度相互影响愈加深刻。加强跨境转让服务或无形资产的增值税征收管理,避免双重征税和非故意不征税成为各国政府面临的难题。OECD在《国际增值税/货物及服务税指南》中提出:在国际贸易中应当按照消费地原则征收增值税,以实现税收中性。本文借鉴OECD《国际增值税/货物及服务税指南》,以案例形式分析了在B2B跨境转让服务或无形资产时,如何应用消费地原则,判断单一位置实体(SLE)、多重位置实体(MLE)的税收管辖权,提出我国应当从坚持消费地原则征税、完善消费地原则判断标准、加强非居民企业增值税管理等方面健全相关增值税制度。

Reduction of Low-grade Manganese Dioxide Ore Pellets by Biomass Wheat Stalk

An investigation on reducing low-grade manganese dioxide ore pellets was carried out by using wheat stalk as reductant. The main impact factors of reduction percent such as particle size, biomass/ore ratio, heating rate, nitrogen flow rate, temperature and time in reduction process were discussed. The morphology and component of manganese dioxide ore particle at different stages were also analyzed by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDS）. The results show the increase of the reduction temperature and time, biomass/ore ratio, and the decrease of particle size, heating rate and nitrogen flow rate can significantly enhance reduction efficiency. The reduction kinetic of the manganese ore is controlled by three-dimensional mass diffusion of gaseous reductive volatiles passing from the surface to the core of the ore particles. The activation energy E and frequency factor A were calculated to be 24.15 kJ.mol^-1 and 166 min^-1, respectively. Biomass pyrolysis volatiles adsorbed onto the surface of the ore particle leads to serious variation of the microstructures and chemical composition of the manganese ore particles.

Accelerated plasma degradation of organic pollutants in milliseconds and examinations by mass spectrometry

The rapid degradation of organic pollutants,process monitoring and online controlling to obtain advanced products and decreased by-products are great and challenging tasks in environmental treatments.Herein,an accelerated plasma degradation in milliseconds was achieved by combining electrospray-based acceleration and plasma-based degradation.Taking the degradation of chloroaniline as an example,97%of the degradation can be achieved in milliseconds.The velocity distribution of droplets was determined to be 40-50 m/s after being degraded for 0.30 ms,which exhibited different degradation behaviors in different milliseconds.Simultaneously,by virtue of the real-time and on-line detection ability of ambient mass spectrometry,intermediates,by-products and advanced products were monitored.Therefore,degradation mechanisms for different degradation times were proposed,which would provide theoretical guidance on obtaining efficient and green degradation.The fabrication,examining and understanding of accelerated plasma degradation not only enlarged application of accelerated reactions,but also promoted green and efficient degradation for environmental treatments.