Investigations on vinylene carbonate. V. Immobilization of alkaline phosphatase onto LDPE films cografted with vinylene carbonate and N-vinyl-N-methylacetamide

Low-density polyethylene (LDPE) films cografted with vinylene carbonate (VCA) and N-vinyl-N-methylacetamide (VIMA) were studied as a matrix for the immobilization of the enzyme alkaline phosphatase (ALP) either by direct fixation or by inserting spacers. When water-soluble alkyldiamines such as diaminoethylene, diaminobutane, diethylenetriamine, and diaminohexane were used as spacers between the matrix and the enzyme, the surface concentration (SC) of the active ALP coupled on the matrix was increased, whereas the effect of the spacer on the SC was dependent on the length of the spacer. Bovine serum albumin (BSA) was preimmobilized onto the LDPE films to provide a better simulation of the biological environment for the enzyme, and the SC of ALP on the matrix was significantly increased by coupling ALP onto the BSA preimmobilized surfaces. Compared to native ALP, some physicochemical properties of ALP could be improved by the covalent immobilization

Investigations on vinylene carbonate. IV. Radiation induced graft copolymerization of vinylene carbonate and N-vinyl-N-methylacetamide onto polyethylene films

Graft copolymerization of binary mixtures of vinylene carbonate (VCA) and N-vinyl-N-methylacetamide (VIMA) onto low density polyethylene (LDPE) films was studied by the mutual γ-irradiation technique. Sufficient amounts of functionally active VCA groups could be grafted onto the surface and the hydrophilicity of the surface was also improved. The grafting of VCA onto polyethylene films in the binary solutions was found to be promoted by the presence of VIMA, thus showing a positive synergism. The VCA content in the graft copolymers was always higher than in the copolymers obtained by homogeneous copolymerization using the same monomer feed composition. The monomer reactivity ratios, as well as a preferential partitioning of the monomers surrounding the polymeric substrate, were considered to explain the grafting reactions in the binary systems

Enhancing Situation Awareness of Chemical Release Through Source Inversion

AbstractSituation awareness is an important function module contained in the information system for regional emergency rescue. To improve the existing emergency information system, a situation awareness model of chemical release is constructed containing three levels, i.e. Data Acquisition, Intelligent Analysis and Simulation & Prediction, in which Intelligent Analysis was designed as an independent functional item for unknown source detection. Combining the receptor data with the atmospheric dispersion model, the source items estimation problem was then converted to a standardized concentration field fitting problem. Particle Swarm Optimization (PSO) was introduced to optimize the combination solution of multi-parameters including source strength, location, height and release time. The effectiveness and applicability of this method was verified through dozens of simulated tests. Further performance comparison with Nelder Mead Simplex Method and Genetic Algorithm show the results: in terms of estimation accuracy, computational efficiency and algorithm robustness, PSO are all superior to the other two algorithms. It can be flexible with different atmospheric dispersion models for fast source inversion in integrated situational awareness system

Electrically and Electrochemically Assisted Nanofiltration: A Promising Approach for Fouling Mitigation

Membrane fouling is regarded as the most critical bottleneck for the widespread application of membrane separation technology. The application of electricity to the surface of membrane provides a promising alternative for fouling mitigation, which may involve the following effects such as electrophoresis, electroosmosis, and electrooxidation. Electrophoresis and electroosmosis influence the movement of charged species (ions or molecules) or movement of fluid adjacent to charged surface under the applied electric field, while electrooxidation functions by degrading species accumulated in the concentration polarization layer and fouling layer to resume permeate flux. Different membrane modules have been developed to satisfy the requirement of electrode assembly. Meanwhile, this coupled process also promotes the development of stable and conductive electrodes including membrane electrodes. Successful applications have been found in the areas of ion separation and treatment of dye wastewater, arsenic contaminated wastewater, antibiotic contaminated wastewater, etc. Compared with microfiltration (MF) and ultrafiltration (UF), existing research in the nanofiltration (NF) is still limited. The increasing applications of NF in practice because of its unique separation capability will definitely trigger more investigations on this electrically or electrochemically combined antifouling technique

Investigations on vinylene carbonate, 2. Copolymerization with N-vinyl-2-pyrrolidone and ethyl vinyl ether

Functional monomers and polymers have received considerable attention in recent years, especially in the biomedical field. In this respect, poly(viny1ene carbonate) is very interesting, because the reactive carbonate groups offer the possibility of coupling with bioactive compounds containing amino groups, e. g. proteins or enzymes. Copolymerization of vinylene carbonate with other vinyl monomers will affect the amount of carbonate groups as well as other properties of the copolymers. In a previous paper we described the preparation and properties of poly(viny1ene carbonate) I), and this paper reports the copolymerization of vinylene carbonate with N-vinyl-2-pyrrolidone and with ethyl vinyl ether