Bioleaching of chalcopyrite by UV-induced mutagenized Acidiphilium cryptum and Acidithiobacillus ferrooxidans

The original strains Acidithiobacillusferrooxidans GF and Acidiphilium cryptum DXI-1 were isolated from the drainage of some caves riched in chalcopyrite in Dexing Mine in Jiangxi Province of China. The optimum temperature and pH for growth were 30 ℃ and 3.5 for Ac. cryptum DXI-1, and 30 ℃ and 2.0 for At. ferrooxidans GF, respectively. For Ac. cryptum DXI-1, the optimum UV radiating time was 60 s and the positive mutation rate was 22.5%. The growth curves show that Ac. cryptum after mutagenesis reached stationary phase within 60 h, which was 20 h earlier than the original strain. For At. ferrooxidans GF, the optimum mutation time was 60 s and the positive mutation rate was 35%. The most active UV-mutated strain At. ferrooxidans GF oxidized all the ferrous after 48 h. The bioleaching experiments showed that bioleaching with the mixture of UV-mutated strains of At. ferrooxidans GF and A c. cryptum DX1-1 （1：1） could extract 3.01 g/L of copper after 30 d, while the extracted copper was 2.63 g/L with the mixture of the original strains before UV-mutation. At the end of the bioleaching experiments, the proportion of the cell density in the cultures ofAc. cryptum DXI-1 andAt.ferrooxidans GF was approximately 1：5.

UV-induced self-assembly of the inclusion complexes formed between a long-chain photochromic spiropyran and cyclodextrins

Photochromic spiropyran with a long chain alkyl substitute can form axial complexes with α-, β-, and γ-cyclodextrin, respeetively. The complexes show normal photochromism. The novel property of the colored forms of the inclusion complexes is that they can assemble into dimers at relatively low concentration or J-aggregates at relatively high concentration. For α-, β-, and γ-cyclodextrin, λmax of the J-aggregates appear at 700 650, and 630 nm, respectively. The sizes of the cavities of cyclodextrins have very little effect on the spectra and decoloration kinetics of the dimers, but have great effects on the spectra of the J-aggregates. Unlike the charge transfer complex of Krongauz, the decoloration process of the dimers or J-aggregates cannot be described by an exponential or a two-exponential kinetics, but obey half-order kinetics very well. Another result that can be deduced from the kinetic analysis is that unlike the dimers formed in apolar solvents or in polymers, which consist of a colored molecule (B’) and a colorless molecule (á) with a composition of A’B’, in the present system, the dimer of the inclusion complex consists of two colored molecules (B). All these results can be interpreted by the proposed structure model and decoloration mechanism.

Tadpole-shaped polymers based on UV-induced strain promoted azide-alkyne cycloaddition reaction

In the present study, we synthesized well-defined tadpole-shaped polystyrene(PS) via the combination of atom transfer radical polymerization(ATRP) and UV-induced strain promoted azide-alkyne cycloaddtion(SPAAC) reaction. A di-bromo ATRP initiator(Br-ini-Br) containing cyclopropenone-masked dibenzocyclooctyne group was used to prepare the linear PS with a cyclopropenone-masked dibenzocyclooctyne in the middle of the chain and bromo groups at both ends(Br-PS-Br). Then we used the single electron transfer-nitroxide radical coupling(SET-NRC) reaction to transfer the bromo end groups to azide groups(N_3-PS-N_3). After UV irradiation, the dibenzocyclooctyne group was quantitatively released, and intramolecularly reacted with alternative azide end group to produce the tadpole-shaped PS based on SPAAC reaction.

Ultravilolet-radiation-induced graft polymerization of acrylamide onto the melt-blown polypropylene filter element by dynamic method

By dynamic method under UV irradiation, commercial melt-blown polypropylene （PPMB） filter element was modified with acrylamide （AAm） using benzophenone （BP） as initiator. Attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscope verified that polyacrylamide chain was grafted on the fiber surface of PPMB filter element. Elemental content analysis with energy dispersive X-ray of fibers revealed that the polymerization content in the inner part of filter element was relatively higher than that in the outer. Degree of grafting changed with initiator concentration, monomer concentration, reaction temperature and reached 2.6% at the reaction condition： CBp=0.06 mol/L, CAAm=2.0 mol/L, irradiation time： 80 min, temperature： 60℃. Relative water flux altered with the hydrophilicity and pore size of filter element. In the antifouling test, the modified filter gave greater flux recovery （approximately 70%） after filtration of the water extract of Liuweidihuang, suggesting that the fouling layer was more easily reversible due to the hydrophilic nature of the modified filter.

Surface Modification of Polyethylene by Heparin for Improvement of Antithrombogenicity

The purpose of this paper was to enhance blood compatibility of polyethylene （PE） film. PE film pretreated by argon plasma was subjected to ultraviolet （UV） -induced graft polymerization with Acrylic acid（AAc） （AAc-grafted PE films, PE-g-PAAc） without photo-initiator, then heparin was covalently immobilized on the PE surface （PE-g-HPAAc）. The surface properties and microstructure of PE-g-PAAc and PE-g-HPAAc were studied by static contact angle measurement, atomic force microscope （AFM）, X-ray photoelectron spectroscopy （XPS） and Attenuated total reflectance Fourier transfer infrared spectroscopy （ATR-FTIR）. It was confirmed that AAc and heparin were successfully immobilized onto the surface of PE film. Results of platelet adhesion experiments indicated that the antithrombogenicity of the modified PE film was remarkably improved.

Tailoring Properties of Biocompatible PEG-DMA Hydrogels with UV Light

Hydrogels are highly water-absorbent hydrophilic polymer networks, which show potential in many biocompatible applications. In previous work, we demonstrated the feasibility of using poly(ethylene glycol) dimethacrylate (PEG-DMA) gels polymerized with a photoinitiator for encapsulation and stabilization of painted biomimetic membrane arrays for novel separation technologies or biosensor applications. These gels were formed from PEG-DMA monomers suspended in phosphate buffered saline (PBS) solution and gelated by radical polymerization in the presence of the photoinitiator Darocur 1173. In this work, we show that the properties of a PEG-DMA hydrogel formed by photoinitiated polymerizetion can be tailored by varying the photocrosslinking time. Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy (RS) showed that the optimal crosslinking time for the gel was 6 - 10 minutes and that the water content of the gels could be tuned in the range of 50 - 90 wt%. The resistivity was between 0.8 - 3.5 Ωm, which is comparable to that of PBS. The low resistivity of the gel makes it compatible for encapsulating membranes for (ion channel based) biosensor applications. With FTIR and RS we identified spectral features of the hydrogel, which may serve as a diagnostic tool to monitor changes in the gels due to variation in parameters such as time, pH, temperature, aging or exposure to chemicals or biological material.