UV radiation induces genome-mediated, site-specific cleavage in viral proteins

Much research has been dedicated to understanding the molecular basis of UV damage to biomolecules, yet many questions remain regarding the specific pathways involved. Here we describe a genome-mediated mechanism that causes site-specific virus protein cleavage upon UV irradiation. Bacteriophage MS2 was disinfected with 254 nm UV, and protein damage was characterized with ESI- and MALDI-based FT-ICR, Orbitrap, and TOF mass spectroscopy. Top-down mass spectrometry of the products identified the backbone cleavage site as Cys46-Ser47 in the virus capsid protein, a location of viral genome-protein interaction. The presence of viral RNA was essential to inducing backbone cleavage. The similar bacteriophage GA did not exhibit site-specific protein cleavage. Based on the major protein fragments identified by accurate mass analysis, a cleavage mechanism is proposed by radical formation. The mechanism involves initial oxidation of the Cys46 side chain followed by hydrogen atom abstraction from Ser47 C(α). Computational protein QM/MM studies confirmed the initial steps of the radical mechanism. Collectively, this study describes a rare incidence of genome-induced protein cleavage without the addition of sensitizers.     

Aspects of Phosphazene Research

This review reports research carried out by the authors during the last 10 years. The research involves the synthesis, characterization, functionalization, and possible utilization of cyclo- and polyphosphazenes. The investigations concern the synthesis of poly(dichlorophosphazene) by polycondensation reaction of dichlorophinoyliminotrichlorophosphorane; the grafting of unsaturated organic substrates (maleic anhydride, maleates or vinyl polymers) onto poly(organophosphazenes) by free radical reactions and the use of the synthesized materials for the preparation of new grafted copolymers or for the superficial modification of conventional organic macromolecules; the synthesis of phosphazenes containing free hydroxylic groups by reaction of methoxy aryloxy- or methoxy oligoethyleneoxy-substituted cyclo- and polyphosphazenes with boron tribromide or trimethylsilyl iodide and their use for the preparation of new phosphazene-based materials (e.g., sol-gel hybrids, thermosetting resins, azodyes, cyclolinear inorganic–organic polymers sometimes containing chiral units, or organic macromolecules having cyclophosphazene residues as pendant groups); and the preparation of oxazoline-containing cyclic and polymeric phosphazene derivatives for the synthesis of photoinitiators, chain extenders, or blend compatibilizers. The possible developments of this research are also envisaged.     

唑烷酮类化合物的光合成研究

通过光化学方法取代传统的金属催化等法合成重要的药物中间体唑烷酮,反应条件温和、操作简便、产率较高且污染少.同时研究了丙酮、甲醇、乙腈3种溶剂与水的不同配比对反应产物的影响.随着溶剂极性增加,立体选择性有一定提高.     

Xanthene dyes/amine as photoinitiators of radical polymerization: A comparative and photochemical study in aqueous medium

The efficiency of several xanthene dyes as photoinitiators of the free radical polymerization in aqueous medium was evaluated. These results show that dyes with triplet quantum yield higher than 0.1 present similar efficiencies, independently of their different chemical structure. A detailed study of the photophysics of the dyes under the polymerization conditions was carried out using laser time-resolved spectroscopies. These studies show that the active radicals are those which formed in the interaction of excited triplet state of the dye with the amine through an electron transfer process. In spite of this, the photoinitiation efficiency is not correlated with the triplet quantum yield. Also, the photophysics studies show that the quantum yield of the different pathways of the decomposition of the charge transfer intermediate is an important parameter to predict the efficiency of these photoinitiator systems. The experimentally measured active radical formation is well correlated with that calculated from the polymerization rate. The presence of heavy atoms in the xanthene ring increases the triplet quantum yield, but decreases the active radical yield, and then the polymerization rate.     

铋系可见光催化剂研究进展

铋系催化剂作为一种新型的光催化材料成为近年来光催化领域的研究热点,尤其在可见光催化降解污染物方面取得一系列重大研究成果。介绍了Bi₂O₃催化剂、钛酸铋系催化剂、复合型催化剂和固溶体型催化剂的研究动态和主要成果,研究的重点将更多集中在光催化机理的深入研究、新型高效光催化剂的研究和合成以及催化剂的负载技术等方面。     

后处理中锕系元素和贵金属元素光化学调价方法

PUREX流程是目前世界上唯一实现工业化应用的后处理流程,该流程的关键技术之一在于调控Pu、Np、Tc等元素的价态。传统上PUREX流程采用化学法调节元素价态,但化学调价有时会遇到困难,比如在硝酸体系下用化学试剂将Np调节至单一价态十分困难。和化学法相比,光化学调价具有方法简单、二次废物体积少、方便远程控制、对材料耐辐照要求不高等优点。将光化学调价和溶剂萃取结合很有潜力实现金属元素的高效分离,只依靠光化学方法将金属离子还原至单质状态也可以实现金属元素的分离和回收。此外,紫外光的照射还能在室温下显著促进UO_2在硝酸溶液中的溶解。     

Effect of formulation and processing conditions on light shielding efficiency of thermotropic systems with fixed domains based on UV curing acrylate resins

Within this study relationships between material formulation and processing parameters and the morphology (vacuole formation) of thermotropic systems with fixed domains (TSFD) for overheating protection purposes were investigated. Main aim was on improving light shielding efficiency of TSFD based on UV curable acrylate resins by optimization of selected key parameters including photo‐initiator type and content, type of reactive diluent, radiation intensity/dose, and thermal treatment of layers during manufacturing. Variations of type of reactive diluent and thermal treatment had a minor effect on overheating protection performance. Utilization of photo‐bleaching photo‐initiator of acylphospine oxide type instead of a blend of conventional Type I (α‐hydroxy ketone type) and Type II (benzophenone) photo‐initiators enabled reduction of radiation dose to achieve properly cured layers. The results revealed that a significant reduction of radiation intensity/dose prevented formation of vacuoles. Consequently, light shielding efficiency of TSFD was enhanced significantly. Nevertheless, obtained scattering domain size was inappropriate for optimum light shielding efficiency and requires further optimization strategies. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3299–3310, 2013     

Photo‐induced protonation and conductivity of polyaniline/poly(ethylene glycol) and polyaniline/[poly(ethylene glycol)‐grafted polyaniline] composites

Composites of polyaniline in its emeraldine base form (PANI‐EB) and photo‐acid generators (PAG) show an increase in conductivity upon photo‐irradiation due to the protonation of PANI‐EB. Such materials may be utilized to fabricate conducting patterns by photo‐irradiation. However, the conductivity obtained by direct irradiation of PANI‐EB/PAG composites was normally quite low (<10^?3 S/cm) due to aggregation of highly loaded PAG. In this work, poly(ethylene glycol) (PEG), which is a proton transfer polymer, was added to PANI‐EB/PAG. Results showed that addition of low M_w (550) PEG significantly enhance the photo‐induced conductivity. Conductivities as high as 10^?1–10⁰ S/cm were observed after photo‐irradiation. This conductivity is comparable to that of PANI‐salt synthesized by oxidizing aniline in the presence of an acid. High M_w (8000) PEG is much less effective than PEG 550, which is attributed to its lower compatibility with PANI. PEG‐grafted PANI (N‐PEG‐PANI) was also studied as an additive. Composites of PANI‐EB and N‐PEG‐PANI showed conductivity as high as 10² S/cm after treatment with HCl vapor. The photo‐induced conductivity of the N‐PEG‐PANI/PANI‐EB/PAG composite reached 10^?2–10^?1 S/cm. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Tailored Remote Photochromic Coloration of in situ Synthesized CdS Quantum Dot Loaded WO3 Films

CdS quantum dot (QD) loaded WO₃ films, fabricated by screen printing and short‐time chemical bath deposition (CBD) techniques, have been proven to have an efficient visible‐light‐driven photochromic response. One of the striking features of such a photochromic system is its remote photochromic characteristic. The photogenerated electrons in CdS are injected into WO₃ to cause the color change of WO₃, while CdS does not show any photochromism. Compared to bare WO₃ films, the spectral sensitivity of remote photochromism in the CdS QD loaded WO₃ films is red‐shifted. The onset wavelength for remote, the decoloration time for CdS QD loaded WO₃ films was found to be significantly shorter than that for bare WO₃ films, probably due to their different electron trapping processes. Bandgap excitation in bare WO₃ creates deeply trapped electrons in the bulk, whereas the electrons injected from the QDs are trapped at shallow surface states in the remote photochromic system. The successful tailoring of photochromic coloration employing a simple procedure would provide numerous opportunities for designing photo‐ and electrochromic materials with the optimal architecture and tunable properties.