Synthesis of methyl methacrylate star-branched polymer with divinylbenzene as a linking agent via controlled/living photopolymerization

HTEMPO-functionalized central cores were formed with divinylbenzene in ＇＇core first＇＇ method,and the four or five arms star polymers were built via controlled/living free radical photopolymerization.The four arms star polymers were also prepared with controlled/living free radical photopolymerization in ＇＇arm first＇＇ method.The resulting polymers had been confirmed by GPC and 1 H NMR.It showed that the star polymers had low polydispersities and molecular weight（M n） with the 85,000-560,000 g/mol range.

Regulations for the Manufacture and Control of Live Poliovirus Vaccine: International Experience and China’s Path

The eradication of poliomyelitis is a landmark achievement in the history of public health, providing strong protection for children’s health. The introduction of the Chinese Regulations for the Manufacture and Control of Live Poliovirus Vaccine is a prerequisite and safeguard for the large-scale production and use of domestically produced live poliovirus vaccines, serving as an indispensable component of vaccine safety. This article, based on archival documents, letters, collections of essays, and oral interviews, examines the historical experience of the development of Chinese Regulations for the Manufacture and Control of Live Poliovirus Vaccine. It contends that the emphasis on localization and the active engagement in international cooperation are critical factors in the swift introduction of Chinese Regulations for the Manufacture and Control of Live Poliovirus Vaccine.

Nitroxide-Mediated Photo-Controlled/Living Radical Polymerization of Methacrylic Acid

The photo-controlled/living radical polymerization of methacrylic acid (MAA) was performed at room temperature by irradiation with a high-pressure mercury lamp using azo initiators and 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator in the presence of (4-tert-butylphenyl)diphenylsulfonium triflate (tBuS) as the accelerator. Whereas the bulk polymerization yielded polymers with a bimodal molecular weight distribution in both the absence and presence of tBuS, the solution polymerization in methanol produced unimodal polymers with the molecular weight distribution of 2.0 - 2.3 in the presence of tBuS. The molecular weight distribution of the resulting poly (MAA) decreased with an in- crease in tBuS. The dilution of the monomer concentration also reduced the molecular weight distribution. The use of the initiator with a low 10-h half-life temperature also effectively controlled the molecular weight. The livingness of the polymerization was confirmed by obtaining linear increases in the first-order conversion versus time, the molecular weight versus the conversion, and the molecular weight versus the reciprocal of the initiator concentration.

LIVING/CONTROLLED GRAFTING FROM POLYMER MICROSPHERES

A review is given of grafting-from methods using living polymerizations, with emphasis on grafting from polymermicrospheres using ATRP.

Vietnam’s Future Water Usage Model: A Controlled Living Experiment

The purpose of this study was to explore the water usage profile of future Vietnamese households by carrying out a controlled living experiment with Vietnamese high-income households. By studying showering time, flow rate and toilet-use frequency of these households, the study revealed the water usage believed to be representative of future households in light of continued urbanization. This study also determined that the average time of showering was 9.7 minutes per person per day with an average flow rate of 12 L/minute for the existing shower head and 6.6 L/minute for the water-saving shower head. Toilet usage frequency was 5.25 times per person per day, and there was no difference with the results for an average (middle-income) household.

CONTROLLED/"LIVING" RADICAL POLYMERIZATION OF STYRENE IN AN AQUEOUS DISPERSION SYSTEM

Atom transfer radical polymerization (ATRP) of styrene catalyzed by cuprous (CuX)/1,10-phenanthroline (Phen) and CuX/CuX2/Phen was conducted in an aqueous dispersed system. A stable latex was obtained by using ionic surfactant sodium lauryl sulfonate (SLS) or composite surfactants, such as SLS/polyoxyethylene nonyl phenyl ether (OP-10), SLS/hexadecanol and SLS/OP-10/hexadecanol, Among which SLS and SLS/OP-10/hexadecanol systems established better dispersed effect during the polymerization, It was found that Phen was a more suitable ligand than N,N,N',N',N'-pentamethyldiethylenetriamine (PMDETA) to maintain an appropriate equilibrium of the activator Cu(I) and the deactivator Cu(II) between the organic phase and the water phase, The effect of several initiators (such as EBiB, CCl4 and 1-PEBr) and the temperature on such a kind of ATRP system was also observed. The number-average molar mass (M-n) of polystyrene (PS) increased with the conversion and the molar mass distribution (M-w/M-n) remained narrow. These experimental data show that the polymerization could be controlled except for the quick increase of monomer conversion and the number-average molar mass of PS in the initial stage of polymerization. Furthermore, the initiator efficiency was found to be low (similar to57%) in CuX/Phen catalyzed system. To overcome this problem, Cu(II)X-2 (20 mol%-50 mol% based on CuX) was introduced into the polymerization system. In this case, higher initiator efficiency (60%-90%), low M-w/M-n of PS (as low as 1.08) were achieved and the molar masses of the PS fit with the theoretical ones.

“LIVING”/CONTROLLED RADICAL POLYMERIZATION OF ETHYL METHYLACRYLATE WITH 2,2’-AZOBISISOBUTYRONITRILE/FERRIC CHLORIDE/TRIPHENYLPHOSPHINE INITIATION SYSTEM

'Living'/controlled radical polymerization of ethyl methacrylate (EMA) was carried out with a 2,2'-azobisisobutyronitrile (AIBN)/ferric chloride (FeCl_3)/triphenylphosphine (PPh_3) initiation system at 85℃. Thc numberaverage molecular weight (M_n) increases linearly with monomer conversion and the rate of polymerization is first order withrespect to monomer concentration. The M_w of PEMA ranges from 3900 to 17600 and the polydispersity indices are quitenarrow (1.09～1.22). The conversion can reach up to～100% and M_w of the polymers obtained is close to that designed. Thepolymerization mechanism belongs to the reverse atom transfer radical polymerization (ATRP). The polymer was end-functionalized by chlorine atom, which acts as a macroinitiator to proceed extension polymerization in the presence ofCuBr/bipy catalyst system via an ATRP process. The presence of ω-chlorine in the PEMA obtained was identified by ~1H-NMR spectrum.

Chemoselective and Living/Controlled Polymerization of Alkenyl Methacrylates by the Phosphonium Ylide/Organoaluminum Lewis Pairs

Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been realized.The P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were synthesized.In the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy groups.The pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)SH.The thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.

Living/controlled polymerization of vinylpyridines into sequence-regulated copolymers by Lewis pair

The poly(vinylpyridine)(PVP) based(co)polymers are of particular interest in materials science, due to their multifunctionality and diverse applications. So far, there is no report on the sequence-regulated copolymerization of vinylpyridines(VPs) and methacrylate monomer in one-step manner yet. Here we designed and synthesized a series of guanidine phosphines as Lewis base(LB), which is combined with bulky organoaluminium to construct Lewis pairs(LPs) for polymerization of VPs. The living/controlled polymerization of 4-vinylpyridine(4-VP) or 2-vinylpyridine(2-VP) can be accomplished with remarkable efficiency by such Lewis pair polymerization(LPP), furnishing polymers with high molecular weight(up to 288 kg/mol) and narrow molecular weight distribution(as low as 1.17). Mechanistic studies reveal the interaction of LPs and formation of zwitterionic intermediates, providing solid evidences to support the proposed polymerization mechanism. More importantly, by simply adjusting the LA dosage, this LPP strategy realizes the unprecedented control over the sequence regulation of 2-VP-based copolymers from gradient to block in one-step manner, regardless of the monomer ratio, which greatly expands the versatility of the LPP.

Efficacy and safety of transcutaneous auricular vagus nerve stimulation combined with conventional rehabilitation training in acute stroke patients: a randomized controlled trial conducted for 1 year involving 60 patients

Transcutaneous auricular vagus nerve stimulation(ta-VNS)is a novel noninvasive treat-ment for stroke that directly stimulates the peripheral auricular branch of the vagus nerve.There have been recent reports that ta-VNS combined with conventional rehabilitation training promotes the recovery of neurological function of patients with acute stroke.However,these were small-sample-sized studies on the recovery of neurological function in patients after percutaneous vagus nerve stimulation in the subacute and chronic phases after stroke.This double-blinded randomized controlled trial involved 60 acute ischemic or hemorrhagic stroke patients aged 18-80 years who received treatment in the Second Affiliated Hospital of Chongqing Medical University.The subjects were randomly assigned to receive ta-VNS or sham ta-VNS combined with conventional rehabilitation training.The follow-up results over 1 year revealed that ta-VNS combined with conventional rehabilitation training greatly improved the recovery of motor and sensory functions and emotional responses compared with sham ta-VNS combined with conventional rehabilitation training.There were no obvious side effects.These findings suggest that ta-VNS combined with conventional rehabilitation training for the treatment of acute ischemic or hemorrhagic stroke patients is safe and effective.

Controlled Radical Polymerization of Styrene in the Presence of Different Copper Complexes and Organic Halides

The polymerization behaviors of Styrene (St) in the presence of CuX/L [X=Cl or Br; L= 2,2 bipyridine (bpy), 1,10 phenanthroline (phen) or 4,7 diphenyl 1,10 phenanthroline (DPP) ] and R X (R=trichloromethyl, benzyl or allyl; X=Cl or Br) have been studied and examined. In a CuCl/bpy/RCl/St system, a bimodal GPC peak at the early stage of polymerization was observed, and a concept of multi active species was proposed to explain this phenomenon. In a CuCl/phen (DPP)/RCl/St system, the \%M\%\-n of polystyrene (PS) increased linearly with St conversion and ln[M] o/[M] also increased linearly with time, indicating the living nature of this system. Furthermore, the stability of the propagating active species in a CuBr/phen/RBr/St system is higher than that in the CuBr/phen/RBr/St system.

Boundedness and liveness enforcement for labeled Petri nets using transition priority

This paper deals with the supervisory control problem of discrete event systems modeled by labeled Petri nets. The system is originally unbounded. First, the solvability of the problem is confirmed. A necessary condition is given and proven for the existence of a feasible priority-based controller based on the notions of liveness and transition invariants. Next, a cyclic behavior graph is constructed, which shows the reachable markings that guarantee the maximum liveness of the system within a given bound vector. Finally, an on-line control strategy is proposed to enforce boundedness and liveness to the given system by appending priority relations to transitions. The dynamic priority relation changes flexibly according to the current state of the system and enforces the system evolving in a bounded and live manner. In addition, numerical examples are studied to verify the validity of the proposed approach that remains the structure of the plant net and is efficient for on-line control.

镍催化可控/活性自由基聚合反应研究进展

可控/活性自由基聚合是近年来发展的温和、聚合反应进程可控、分子结构可设计性强的自由基聚合反应技术,其核心在于活性自由基中间体与催化剂/链转移剂的可逆活化/失活过程,常用于极性单体聚合制备结构多样的有机高分子材料。镍催化剂具有多变的中心金属价态及多样的聚合反应机理,在可控/活性自由基聚合领域存在独特的优势。对近年来原子转移自由基聚合(ATRP)和有机金属控制的活性自由基聚合(OMRP)中的镍催化剂结构、聚合反应机理、反应行为和产物结构特征进行了综述,并对镍催化的可控/活性自由基聚合未来发展方向和应用前景进行了展望。

微反应器内阳离子聚合研究进展

阳离子聚合是制备高分子材料的重要方法之一。因阳离子聚合反应活性高、可控性差,采用传统的方式对其进行深入研究难度往往很大。微反应器技术因其优异的过程控制能力在阳离子聚合研究中表现出得天独厚的优势。本文介绍了微反应器内传统阳离子聚合和活性阳离子聚合的研究进展,论述了微反应器对提高异丁烯、乙烯基醚类单体阳离子聚合反应可控性、反应效率以及机理研究的重要作用,探讨了阳离子聚合体系和装备理性设计的方向。

基于品管圈的早期预警性干预在老年认知功能障碍患者走失管理中的应用

目的探讨基于品管圈的早期预警性干预在老年认知功能障碍患者走失管理中的应用效果。方法选取2022年9月至2023年6月上海交通大学附属上海市第六人民医院老年科收治的150例老年认知功能障碍患者为研究对象,按随机数字表法分为两组,每组75例。对照组给予常规护理,试验组在对照组基础上给予基于品管圈的早期预警性干预。比较两组干预前后走失情况、认知能力和独立生活能力。结果试验组走失率低于对照组,走失时间短于对照组,差异有统计学意义(P<0.05)。干预后,两组蒙特利尔认知评估量表各维度评分、功能独立能力评价量表各维度评分及总分均高于干预前,且试验组高于对照组,差异有统计学意义(P<0.05)。结论基于品管圈的早期预警性干预可有效降低老年认知功能障碍患者的走失率,提高认知能力和独立生活能力。

超支化聚合物在生物医学材料中应用研究进展

超支化聚合物(HBPs)具有高活性功能端基,便于修饰改性,能够设计合成结构明确且具有特定功能的高分子材料,在生物医学领域具有潜在应用价值。可控/活性自由基聚合(CLRP)技术在聚合物合成领域受到广泛关注,并将其运用到医疗产品、纳米材料、航天器件等众多领域中。近年来,在合成具有生物可降解和生物相容性的HBPs的发展方面已取得了诸多进展,对HBPs在生物医学领域的最新研究进展进行了总结,重点介绍了HBPs在药物传递、基因转染、组织工程、抗菌/防污材料、生物医学成像等方面的应用,并对HBPs的发展前景进行了展望。

Manufacturing process of water-soluble salt-based ceramic cores based on vat photopolymerization

Water-soluble salt-based ceramic cores can be recycled and have excellent high-temperature chemical stability.In this work,vat photopolymerization was successfully applied to water-soluble salt-based ceramic cores for the first time.The powder raw materials of the printing suspension were sodium chloride and alumina.High-precision green bodies were manufactured by optimizing suspensions and parameters.In addition,the postprocessing method was optimized according to the microstructure and mechanical properties.The sintered part had a high bending strength and smooth surface.Finally,the dissolution rate and moisture resistance were compared under different dissolution and storage conditions.Compared to traditional manufacturing methods,vat photopolymerization enables the production of complex structures without molds and reduces production costs.This technology is suitable for the rapid iteration of complex structural parts and can be applied to precision parts in aerospace,military,and other technical fields with high cost-effectiveness and sustainability.

带电安装磁控式断路器工作过程的安全管控

针对配网工程中以带电作业方式带负荷安装磁控式断路器的安全风险,通过对磁控式断路器特殊构造以及作业过程中相关问题的分析,提出了一种带电作业方式实现带负荷加装磁控式断路器的安全管控,保障了带电作业的顺利实施和作业人员的人身安全。

行政激活自治:农村人居环境治理有效的实践逻辑

作为满足农民美好生活需要的组成部分,农村人居环境治理实践正在各地展开。调研发现,囿于“服务者角色”对“规制职能”的替代、“技术性治理”对“地方知识”的拒斥、“控制权下沉”对“政策转化”的限制,农村人居环境治理中的行政支配造成“自治”及其背后的农民主体处于“被围困”状态。为此,应创设村庄自治机制和支持结构、实现行政服务和规制职能统合,塑造知识民主观念和沟通机制、完成行政技术与地方知识适配,厘清乡村关系和做好政策转换、保证行政治权与自主治理有效等,以达成农村人居环境治理有效、有力和可持续。

CE-EMMA法测定乙脑灭活疫苗中乙二胺四乙酸二钠残留量

目的:建立毛细管电泳(CE)结合电泳中介微分析(EMMA)测定乙脑灭活疫苗中乙二胺四乙酸二钠(EDTA-2Na)残留量的方法。方法:运行缓冲液为0.025 mol•L^(-1)磷酸氢二钠缓冲液(pH 2.5),在线络合金属离子为1.5 mg•mL Fe^(3+),孵育时间3 min,分离电压-25 kV,紫外检测波长257 nm,压力进样5000 Pa×5 s,检测温度为25.0℃。结果:EDTA-2Na在0.01~0.5 mg•mL^(-1)的浓度范围内呈现良好的线性关系,r为0.9999,最低检测限为5μg•mL^(-1),测定样品RSD小于2.87%,加样回收率为94.13%~105.56%。结论:该方法操作简便,准确度高,稳定性好,可用于乙脑灭活疫苗中EDTA-2Na残留量的测定。