Preparation of PVC/PVP composite polymer membranes via phase inversion process for water treatment purposes

In this work, new composite membranes were successfully prepared via phase inversion technique using polyvinyl chloride(PVC) and polyvinylpyrrolidone(PVP) as polymers and tetrahydrofuran(THF) and N-methyl-2-pyrrolidone(NMP) as solvents. The prepared membranes have been characterized by scanning electron microscope(SEM), and fourier transforms infrared spectroscopy(FTIR). The scanning electron microscope results prove that the prepared membranes are smooth and their pores are distributed throughout the whole surface and bulk body of the membrane without any visible cracks. The stress–strain mechanical test showed an excellent mechanical behavior enhanced by the presence of PVP in the prepared membranes. The membranes performance results showed that the salt rejection reached 98% with a high flux. This, in turn, makes the prepared membranes can be applied for sea and brackish water treatment through membrane distillation technology.

探索建立公安联合指挥机制提升驾驭社会治安局势能力

随着我国经济转轨、社会转型，利益格局深刻调整，各类社会矛盾不断增多，风险因素日益突出，公共安全形势复杂加剧，由此引发的各类重大突发事件越来越多，严重影响社会稳定。公安机关作为维护国家安全和社会稳定的主力军，如何提升动态化、信息化条件下社会治安局势驾驭能力，有效防范应对公共安全事件，是各级公安机关必须面对的挑战和亟需破解的难题。苏州市公安局通过探索建立公安联合指挥机制，对如何进一步推动立体化防控体系建设，完善公共安全事件预防处置机制，提升驾驭社会治安局势能力进行了实践与思考。