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The RbCl ZnCl2 and CsCl ZnCl2 binary systems with different proportions are firstly prepared to determine the phase equilibrium relation using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) methods. The phase diagrams of RbCl ZnCl2, CsCl ZnCl2 and RbCl CsCl are thus critically optimized by thermodynamic modeling based on the available experimental values. The associate solution model (ASM) is used to describe the liquid phases of RbCl ZnCl2 and CsCl ZnCl2 binary system, and the substitutional solution model (SSM) is applied for the RbCl CsCl binary system. All Gibbs energies of intermediate compounds are treated with the Neumann-Kopp rule. In light of this, a set of self-consistent thermodynamic database is obtained and applied to predict the thermodynamic properties of the RbCl CsCl ZnCl2 ternary system by merging the Gibbs energies in its subsystems via the Kohler-Toop interpolation method. These results could provide effective data supporting for the selection and optimization of multi-component molten salts for the concentrating solar power (CSP) plants.

FLiBe (2LiF-BeF 2 ) molecular structure was investigated by infrared (IR) absorption spectroscopy combined with density functional theory (DFT) calculations. An instrument was designed and implemented to obtain the in situ IR absorption spectra of molten FLiBe salt. IR absorption spectrum of molten FLiBe salt was obtained at 600 °C and the spectra assignment were aided with the density functional theory (DFT) calculations, which indicated that liquid FLiBe salt can form fluoberyllate of [BeF 4 ] 2 − . The IR spectrum of FLiBe powder acquired at room temperature furthers to imply that [BeF 4 ] 2 − was formed and combined with two Li + to make neutral molecule of Li 2 BeF 4 . Based on the geometry optimization, absorption peaks were also assigned and detailed vibration information was supplied.

Tonalide was extensively used as fragrances in various personal care products and recognized as emerging contaminant recently. In this study, the transient reactions of hydrophobic tonalide with hydroxyl radical ( OH), one of highly reactive oxygen species (ROSs), was firstly investigated in acetonitrile through direct observation using laser flash photolysis. Two transient intermediates were formed with the peak centered at 360 and 450 nm, and the bimolecular reaction rate constants of tonalide with OH were determined in both water and acetonitrile solutions with values of 4.04 × 109 and 1.95 × 109 M−1 s−1, respectively. Then, the photocatalytic experiments in a heterogeneous TiO2 system were carried out to study the decomposition kinetics of tonalide with OH, which was confirmed as the dominant ROSs in photocatalytic system. Five degradation products were identified with molecule weight of 260, 272 and 274. Finally, the potential risks of reaction products formed through the reactions of tonalide with OH were further investigated. It is found that the toxicity towards luminescent bacterium (Photobacterium phosphoreum) was not changed so much, and the estrogenic activity increased a little bit during the degradation of tonalide by OH.

The degradation of p-nitrophenol (p-NP) based on OH radicals (HO∙), HO2 radicals (HO2∙) and O2 in aqueous solution was investigated using theoretical computational methods. The complete degradation mechanisms of reaction between p-NP and HO∙ were explored by density functional theory (DFT) methods. The 4-nitrophenoxy radicals and 1,2-dihydroxy-4-nitrocylohexadienyl radicals are confirmed to be major intermediates of the HO∙-initiated reactions in aqueous phase, which consistent with experimental results. The chemical structures of some products (2,4-dihydroxycyclohexa-2,4-dien-1-one and 4-nitrocyclohexa-3,5-diene-1,2-dione) which were not identified in the experiment are determined. New favorable formation channels for some intermediates were found. The primary reactions initiated by HO∙ or HO2∙ with p-NP reveals that HO∙-initiated degradation is the dominant reaction. HO2∙ and O2 can enhance the degradation extent of p-NP in further reactions. Rate constants of the elementary reactions and overall rate constants were calculated. In addition, the HO∙-initiated primary reactions in a water box of 500 water molecules were studied using Monte Carlo simulation. All the OH-addition reactions are barrierless and highly feasible. The observed dynamic reaction process is similar to the DFT calculation prediction. Furthermore, the eco-toxicity evaluation shows that important products are harmless or harmful to aquatic organisms, and are much less toxic than p-NP.

Volumetric absorption of solar radiation (VASR) is an important parameter which directly determines the absorption efficiency of molten salt as the direct receiver. Accordingly, VASR directly impacts on power generation efficiency. Therefore, investigating the VASR is dramatically important involving calculation method and the effect factors. Molten nitrate/nitrite salt of 53 wt% KNO3-40 wt% NaNO2-7 wt% NaNO3 (HTS) on account of low melting point and high specific heat etc. merits was used in concentrate solar power field, so it was selected to be studied in this work. High-temperature ultraviolet-visible (UV–Vis) and infrared absorption (IR) spectrometers built by ourselves were used to obtain the absorption spectra of HTS. A calculation method was established by ourselves, based on which the VASR was calculated. Furthermore, various effects coming from bubbles, temperature, and additive were also studied. This will supply important help for the design of solar power plant.

The kinetics and mechanisms of ultraviolet photochemical transformation of propylparaben (PPB) were studied. Specific kinetics scavenging experiments coupled with quantum yield determinations were used to distinguish the roles of various reactive species induced by self-sensitized and direct photolysis reactions, and the excited triplet state of PPB ((PPB)-P-3*) was identified as the most important species to initiate the photochemical degradation of PPB in aquatic environments. The computational results of time-resolved absorption spectra proved that (PPB)-P-3* is a highly reactive electron acceptor, and a head-to-tail hydrogen transfer mechanism probably occurs through electron coupled with proton transfer. Physical quenching by, or chemical reaction of (PPB)-P-3* with, O-2 was confirmed as a key step affecting the initial PPB transformation pathways and degradation mechanisms. The transformation products were identified and the toxicity evolutions of PPB solutions during photochemical degradation under aerobic and anaerobic conditions were compared. The results indicate that anaerobic conditions are more likely than aerobic conditions to lead to the elimination and detoxification of PPB but less likely to lead to PPB mineralization. (C) 2014 SETAC

In this paper, the photochemical and photobiological characters of the active radicals of berberine (BBR) was investigated for finding an efficient and safe photosensitizer with highly active transient products using in Photodynamic therapy (PDT) study. The active species of BBR was generated and identified by using pulse radiolysis method. In neutral aqueous solution, BBR react with hydrated electron and hydroxyl radical, forming the radical anion and neutral radical of BBR, and the related reaction rates were determined as 3.5 × 10 10 and 6.7 × 10 9 M − 1 s − 1 , respectively. Further, the capability of BBR to photosensitize DNA cleavage was testified by laser flash photolysis (LFP) method, the results demonstrated that BBR neutral radical could react with guanine mononucleotide ( K = 1.9 × 10 9 M − 1 s − 1 ) via electron transfer to give the guanine neutral radical. Additionally BBR selective cleavage single and double strand DNA at guanine moiety was observed. Finally, combining with the thermodynamic calculation, the possible photodamage mechanism of dGMP and DNA induced by BBR was clarified.

The atmospheric OH-initiated degradation mechanisms of dimethy phthalate (DMP) are analyzed at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) level of theory. The principal products detected experimentally are confirmed by this study while several major intermediates are reported for the first time. Additionally, the pathway scheme of hydroxylation reaction of DMP is proposed. The results about initial steps indicate that hydroxyl radical is most likely to be added to the ortho-carbon atom among additional reactions, while H atoms in methyl group are the most favorable to be abstracted by the OH radical. The rate constants of the elementary reactions over the temperature of 200-400 K were deduced using RRKM theory. The overall rate constant of the title reaction is 1.18 x 10(-12) cm(3) molecule(-1) s(-1) at 298 K and 760 Torr while H abstraction reactions predominate. According to the rate constants given at different temperatures, the Arrhenius equation is fitted. The atmospheric half life of DMP with respect to OH is estimated to be 6.8 days. (C) 2013 Elsevier Ltd. All rights reserved.

The properties of norfloxacin (NFX) and its 4′-N-acetyl derivative (ANFX) are investigated in different pH aqueous solutions and H2O-CH3CN mixed solutions, to determine the effects of pH and polarity on their ground and excited states. The triplet states of NFX and ANFX are affected more by pH than by polarity. The pH dependence of the NFX and ANFX triplet states is likely due to the different quantum yields of different protonated forms. Steady-state fluorescence, time-resolved fluorescence, and laser flash photolysis experiments at different pH values provide clear evidence of the involvement of different intramolecular charge-transfer pathways in the singlet states of NFX and ANFX. The different electron-donating capacities of 1-N, 1′-N, and 4′-N under different conditions determine the major pathway.

In order to investigate the possible role of hydroperoxyl radical (HO2 center dot) in the degradation of p-nitrophenol (p-NP) attacked by hydroxyl radical ((OH)-O-center dot), a series of experiment have been elaborately designed using UV light photolysis, pulse radiolysis and intermediate analysis. It has been demonstrated that (OH)-O-center dot is the dominant reactive oxygen specie, meanwhile both O-2 and HO2 center dot can enhance the degradation efficiency of p-NP. The accelerative effect of HO2 center dot has firstly been distinguished from that of O-2 by identifying the products in the systems of p-NP + (OH)-O-center dot, p-NP + (OH)-O-center dot + O-2 and p-NP + (OH)-O-center dot + O-2 + HO2 center dot. The possible reaction mechanism involved in the degradation of p-NP has been proposed, especially in the presence and absence of HO2 center dot. The ring open of phenoxy-type radical may be the key step in the accelerative effect of HO2 center dot. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

In the present paper, the interaction between model protein lysozyme (Lys) and antitumorigenic berberine (BBR) was investigated by spectroscopic methods, for finding an efficient and safe photosensitizer with highly active transient products using in photodynamic therapy study. The fluorescence data shows that the binding of BBR could change the environment of the tryptophan (Trp) residues of Lys, and form a new complex. Static quenching is the main fluorescence quenching mechanism between Lys and BBR, and there is one binding site in Lys for BBR and the type of binding force between them was determined to be hydrophobic interaction. Furthermore, the possible interaction mechanism between BBR and Lys under the photoexcitation was studied by laser flash photolysis method, the results demonstrated that BBR neutral radicals (BBR(-H)) react with Trp (K=3.4×10(9)M(-1)s(-1)) via electron transfer to give the radical cation (Trp/NH(+)) and neutral radical of Trp (TrpN). Additionally BBR selectively oxidize the Trp residues of Lys was also observed by comparing the transient absorption spectra of their reaction products. Through thermodynamic calculation, the reaction mechanisms between (3)BBR and Trp or Lys were determined to be electron transfer process.

A mild pre-irradiation method was used to graft glycidyl methacrylate (GMA) onto polyethylene (PE) non-woven fabric (NF). The polymer was irradiated by electron beam in air atmosphere at room temperature. The degree of grafting (D-g) was determined as a function of reaction time, absorbed dose, monomer concentration and temperature. After 30 kGy irradiation, with 5% GMA, surfactant Tween 20 (Tw-20) of 0.5% at 55 degrees C for 15 min, the trunk polymer was made grafted with a D-g of 150%. Selected PE-g-PGMA of different D-g was modified with aminated compounds such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA). The obtained amine-type adsorbents were prepared to remove copper and uranium ions from solution. It was shown that at least 90% of copper and 60% of uranium with the initial concentration from 3 to 1000 ppb can be removed from water. (C) 2011 Elsevier Ltd. All rights reserved.

The mechanism and kinetic properties of OH-initiated gas-phase reaction of 2,4-dibrominated diphenyl ether (BDE-7) were studied at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level of theory. Two types of reactions, hydroxyl addition and hydrogen abstraction, were investigated. The calculation results indicate that addition reactions, except for the bromo-substituted one, have lower barriers than hydrogen abstraction reactions. Moreover, hydroxyl radicals are likely to react with phenyl ring without bromine atoms. Rate constants were deduced over 200-1000 K using canonical variational transition state theory with small curvature tunneling contribution. At 298 K the calculated rate constant for the title reaction is 3.76 x 10(-12) cm(-3) molecule(-1) s(-1). (C) 2012 Elsevier B.V. All rights reserved.

GFX in water, at pH 7.0, shows intense absorption bands with peaks at 284 and 333 nm, ( e =24,670 and 12,670 M −1 cm −1 ). Both the absorption and emission properties of GFX were pH-dependent; the p K a values for the protonation equilibria of the ground state (5.7 and 8.9) and excited singlet state (3.6 and 7.5) of GFX were determined spectroscopically. GFX fluoresces weakly, with a maximum quantum yield for fluorescence emission (0.06) at pH 4.7. A series of experiments were performed to characterize the transient species of GFX in aqueous solution using laser flash photolysis and pulse radiolysis. GFX undergoes monophotonic photoionization with a quantum yield of 0.16 on a 355 nm laser excitation. This process leads to the formation of a long-lived cation radical with a maximum absorption at 380 nm. Triplet–triplet absorption had maximum absorption at 510 nm. The reaction of GFX with one-electron oxidant N 3 • was investigated and the bimolecular rate constant was determined to be 3.1×10 9 M −1 s −1 .

Poly(allylamine-co- N,N’ -methylenebisacrylamide) magnetic nanogels (PAAm-Fe3O4) were prepared by photochemical polymerization of allylamine and N,N′ -methylenebisacrylamide in magnetite aqueous suspension under UV irradiation. The composition, zeta potential, morphology, particle size distribution and magnetic properties of the product were characterized in detail. To explore the initiating process of polymerization, laser flash photolysis was used to investigate the interaction between Fe3O4 nanoparticles and organic electron donor by employing aniline as the probe molecule, an analogue of allylamine. It indicated an occurrence of electron transfer process from the organic electron donor to Fe3O4 which may be critical to initiate polymerization reaction of amino monomer and form polymer shell on the surface of Fe3O4 nanoparticles. The mean diameter and diameter distribution of PAAm-Fe3O4 can be tuned in a moderate range by varing irradiation time or volume of the dropped monomer. The experimental results also proved that nearly spherical PAAm-Fe3O4 possessed a core-shell structure and positive zeta potential and high magnetic content of nearly 88%. Moreover, it behaved quasi-superparamagnetic at room temperature and its saturation magnetization reached to 50 emu/g. Finally, a possible formation mechanism of magnetic nanogel was proposed.

The reactions between quaternary ammonium ionic liquids ([Me3NC2H4OH]+[Zn2Cl5]−, abbrev. Ch-Zn2Cl5) and one-electron oxidant (SO 4 •− ), have been studied by nano-second laser photolysis techniques. The mechanism of monophotonic ionization by 266 nm laser excitation was suggested and the quantum yield was estimated to be 0.04. The second-order decay rate constant of SO 4 •− oxidation reactions at 460 nm, 1.3 × 109 M−1 s−1, was almost equal to the product rate constant of 1.5 × 109 M−1 s−1 at 320 nm in Ch-Zn2Cl5 aqueous solution showing that the decay and the product were synchronic. Comparison of Ch-Zn2Cl5 with chloride choline and ZnCl2 showed that the anion Zn2Cl5 − played an important role in photoionization while choline cation had little function on its photolysis and radiolysis. The present study would be helpful for understanding the application of ionic liquids in the field of electrochemical deposition.

Pt/Ru deposited on multi-walled carbon nano-tubes (MWCNTs) was prepared with water/iso-propanol solutions containing Pt(IV) and Ru(III) ions by gamma-irradiation. The water/iso-propanol ratio (v/v), additive amount of surfactant, the concentration ratio of Pt(IV)/Ru(III) ions and the total absorbed doses (kGy) were evaluated as synthesis parameters. The sample morphology was characterized by SEM and the Pt/Ru atomic ratio was obtained by EDX. It has been found that multi-walled carbon nano-tubes can be well distributed in the water/iso-propanol solution with additive of surfactant. Pt(IV) and Ru(III) ions can be reduced by both of hydrated electron and radical of iso-propanol produced from hydrogen abstraction reaction. The Pt/Ru atom ratio can be controlled by changing the ratio of Pt(IV)/Ru(III). Small nano-particles of Pt/Ru deposited on MWCNTs can be obtained for possible application of electro-catalysts in the proton exchange membrane fuel cells (PEMFC) under optimum conditions with absorbed doses, amount of surfactant, water/iso-propanol ratio and so on. The reduction of Pt(IV)/Ru(III) ions, in the aqueous solution with additive of surfactant was also studied by use of pulse radiolysis and the mechanism involved in the reduction process has been proposed. (C) 2010 Elsevier Ltd. All rights reserved.

The photochemistry of several fluoroquinolone antibiotics (FQs). including enoxacin (ENX), norfloxacin (NFX). and ciprofloxacin (CPX), have been investigated in neutral aqueous solution by laser flash photolysis and pulse radiolysis Transient absorption spectra of FQs were observed and transient species were assigned The absorption maxima (lambda(max)) of triplet states of ENX. NFX and CPX were located at 520 nm, X 620 nm and 610 nm, respectively. The radical anions of FQs were characterized by lambda(max) = 370 nm Reactions of the FQ triplet states with amino acids (tyrosine [TyrOH]. tryptophan [TipH], glycine [Gly] and cysteine [CyS]) were investigated in different conditions. All three FQ triplet states can oxidize TrpH and TyrOH. The FQ radical anions and oxidized radicals of TrpH (Trp(center dot)) and TyrOH (TyrO(center dot)) were directly observed. Under aerobic conditions, the photooxidation of TrpH and TyrOH involves both Type I and Type II mechanisms. There were no distinct quenching reactions of the FQ triplet states by Gly and Cys in N(2)-saturated aqueous solutions (C) 2010 Elsevier B.V All rights reserved.

The laser photolysis of N-diisopropyl phosphoryl tryptophyl tyrosine dipeptide methyl ester (N-DiPP-TrpH-TyrOH) has been carried out utilizing a KrF(248 nm) laser. The direct intramolecular ET between TrpH+ residue and TyrOH residue was detected first and the ET bet-ween Trp and TyrOH became slow. It was suggested that phosphoryl group stabilize neighbour radical of aromatic ring by hyperconjugation. In combination with computer modeling we obtained the kinetic parameters of the ET and proved that phosphoryl groups took part in the process of ET. The results should be significant for biological system since every biological process involves the phosphorylation or nonphosphorylation.

The degradation kinetics of p-nitrophenol (p-NP) exposed to 254/185 nm UV light were studied in two modes, i.e., 254 nm UV light intensity enhanced mode and normal mode. It was observed that the extra 254 nm UV light source accelerated the degradation process both in the presence and the absence of oxygen. Considering that hydroxyl radical (*OH) is the dominant factor that causes the degradation of p-NP, the enhanced degradation that occurred in the presence of the extra light source was attributed to the synergistic effect between *OH attack and the primary reactions initiated by 254 nm UV light. The synergistic effect has been confirmed by 266 nm laser flash photolysis (LFP) experiments. It is demonstrated that the phenoxy radical generated from the photoionization of p-NP is capable of reacting with *OH. On the basis of these results, it should be noted that UV light could cause more severe damage to p-NP attacked by *OH in aqueous solution.

Ethanol production from lignocellulose by recombinant yeast with high level expression of heterologous cellulase genes has been a major anticipation. The native secretion signal sequence of the cellulase endoglucanase I (eg1) gene was replaced by Saccharomyces cerevisiae mating factor alpha prepro-leader sequence (MFalpha). The transformants containing native secretion signal (Y(1)) and MFalpha secretion signal (Y(2)) were characterized with respect to gene expression and growth on cellulose substrate. Increased enzyme activity and cellulose utilization were observed. The enzyme activity of Y(2) was 0.084 U/ml, 61.5% higher than Y(1) (0.052 U/ml). The sufficiency parameter (S value) was raised from 0.6 to 0.84. MFalpha signal peptide was more efficient than the native signal peptide of eg1 gene, suggesting that signal peptide replacement is an efficient way to enhance the cellulase expression level in yeast, for cellulose-derived ethanol production.

Both transient photolysis and steady-state photo-degradation experiments were performed to gain insight into the kinetics and mechanisms of degradation of p-mitroaniline (p-NA) in aqueous solutions. Monophotonic photo-ionization of p-NA was characterized by 266nm Laser Flash Photolysis (LFP). The quantum yield of eaq(-) was calculated. Radical cations and neutral radicals of p-NA were identified, respectively. The LFP of p-NA with H(2)O(2) in aqueous Solutions was investigated for the first time. For steady-state photodegradation, degradation of p-NA was observed at diverse irradiation conditions under 254 run UV light. Direct photo-degradation of p-NA by 254 nm UV light in aqueous solution was very difficult. Once H(2)O(2) was added into the experimental system, degradation of p-NA was enhanced remarkably. In the absence of O(2), degradation rate increased rapidly along with the irradiation time and reached 80% at 10 min. p-NA could be totally removed after 15 min in UV/H(2)O(2) process. In the presence of O(2) and H(2)O(2), degradation rate increased linearly along with the irradiation time and reached 80% at 7.5 min. p-NA Could be totally removed after 10 min. The mechanisms behind the photo-degradation of p-NA were discussed. (C) 2008 Elsevier B.V. All rights reserved.

Poly(methacrylic acid) (PMAA) grafted polyethersulfone (PES) powder was prepared by gamma-ray irradiation-induced graft polymerization. The existing of the PMAA side chains in the grafted powder was proved by FT-IR spectroscopy. Then, pH dependent microfiltration (MF) membranes were cast from PES-g-PMAA powder with different degree of grafting (DG) under phase inversion method. The contact angle, mean pore size and swelling behavior of MF membranes were measured. The morphology was studied and the water filtration property was also tested. The results showed that the mean pore sizes and filtration properties of MF membranes cast from PES-g-PMAA powder varied with pH. In the most variant case, the flux of acid solution was about four times as that of basic solution for the MF membrane cast from PES-g-PMAA with DG of 20.0%. (C) 2009 Elsevier B.V. All rights reserved.

Both transient photolysis and steady-state photo-degradation experiments were performed to gain insight into the kinetics and mechanisms of degradation of p-nitroaniline (p-NA) in acetonitrile (MeCN) solutions. Complete degradation of p-NA was observed at diverse irradiation conditions under 254 nm UV light. Once H(2)O(2) was added into the experimental system. degradation of p-NA was enhanced remarkably. The removal rate increased rapidly with increment of the irradiation time and reached 90% at 30 min. p-NA could be totally removed after 90 min in UV/H(2)O(2) process. In the presence of O(2) and H(2)O(2), removal rate increased linearly with increment of the irradiation time and reached 90% at 10 min. p-NA could be totally removed after 20 min in UV/(O(2) + H(2)O(2)) process. For transient photolysis, excited states of p-NA were observed after 355 and 266 nm laser flash photolysis (LFP). The transient absorption spectra were recorded and bimolecular rate constant of 6.89 x 109 M(-1) s(-1) was calculated for the self-quenching of (3)p-NA(*). Production of (3)p-NA(*) in MeCN and H(2)O mixed solution was also studied. LFP of p-NA with addition of H(2)O(2) was investigated for the first time. (c) 2008 Elsevier B.V. All rights reserved.

The behavior of melatonin in the riboflavin-sensitized photo-oxidation of lysozyme was monitored. Melatonin was found to prevent aggregation of protein and the decrease of enzyme activity induced by photo-oxidation. Electron spin resonance experiments showed that photo-oxidation of lysozyme in the presence of riboflavin resulted in formation of protein radicals, and melatonin was highly effective in reducing the formation of protein radicals. Direct evidence of melatonin's ability for quenching the triplet state of riboflavin and singlet oxygen was presented. A mechanism of the protective effect of melatonin on photo-oxidation of protein was proposed and the physiological relevance was discussed. (C) 2008 Elsevier B.V. All rights reserved.

One-pot synthesis of magnetic nanogels with excellent biocompatibility via the photochemical method is reported in this paper. Poly(PEGMA) modified superparamagnetic nanogels (poly(PEGMA) magnetic nanogels) were synthesized by in-situ polymerization using poly(ethylene glycol) methacrylate (PEGMA) as the monomer and N, N′-methylene-bis-(acrylamide) (MBA) as the cross-linking agent in magnetite aqueous suspension under UV irradiation. The surface functional groups and components of magnetic nanogels were analyzed by Fourier transform infrared spectroscopy (FTIR) and a thermogravimetric analyzer (TGA). The results indicated that the poly(PEGMA) magnetic nanogels were synthesized successfully by coating poly(PEGMA) on the Fe3O4 nanoparticles under UV irradiation, and the Fe3O4 nanoparticles content in this nanogels was above 50 wt%. The morphology, size, zeta-potential and magnetic property were also characterized. The magnetic nanogels had a nearly spherical shape and core-shell structure, the average size in aqueous system measured by photon correlation spectroscopy (PCS) was 68.4 nm, which was much bigger than that in the dry state, the nanogels behaved superparamagnetically with saturated magnetization of 58.6 emu/g, and the zeta-potential was −16.3–−17.3 mV at physiological pH (6.8–7.4) which could help to maintain stability in blood. The preliminary application as drug carrier was made and the doxorubicin-loaded magnetic nanogels had an excellent property in slow-release. The experiment indicated that the magnetic nanogel was an ideal candidate carrier in target drug delivery systems and other biomedical application.

A wide range of pharmaceutical compounds have been identified in the environment, and their existence is a topic of growing concern, both for human and ecological health. The work described here has investigated the photolytic properties of L(+)-α-phenylglycine (L-α-PG-H) in aqueous solution as it can be degraded by photo-catalysis. In 266 nm laser flash photolysis of aqueous solution of L-α-PG-H saturated with nitrogen, two transient absorption bands are observed at 280–330 nm and 450–800 nm, respectively, due to L-α-PG-H radical cation and hydrated electrons (e aq − ). Then e aq − reacts with L-α-PG-H to form the L-α-PG-H radical anion. Decaying rate constants of e aq − observed at 720 nm is to be 8.9 × 108 dm3 mol−1 s−1. The rate constant for oxidation of L-α-PG-H by SO4 − is calculated as 4.5 × 108 and 4.3 × 108 s−1 mol−1 dm3, respectively. The dissociation constants (pKa) of L-α-PG-H is 3. Excited triplet of L-α-PG-H in solution is formed by laser flash photolysis. The quench rate constant of L-α-PG-H excited triplet (k s) is determined to be 1.3 × 107 dm3 mol−1 s−1 and k 0 is equal to 1.7 × 105 s−1.

Layered double hydroxides (LDHs) are a class of artificially constructed materials that have potential applications in a wide range of fields, including biomedical research and drug development. In this study, we have successfully intercalated folic acid into LDH using two different approaches: co-precipitation and ion exchange. The resultant LDH–folic acid constructs were then characterized by powdered sample X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), thermogravimetry and differential thermal analysis (TG–DTA). XRD data demonstrated that folic acid molecules remained intact and stable between the hydroxide layers in LDH particles constructed by both co-precipitation and ion-exchange methods, with interlayer spacings of 15.3 and 16.0 A, respectively. Particle size and surface topography were also determined using TEM. Cytotoxicity test revealed that neither LDH nor LDH–folic acid nanohybrids were toxic to the cell line 293T, suggesting that they can be used as a safe and noncytotoxic drug delivery system. Furthermore, the buffering effect of the intercalated LDH was evaluated. This work provides fundamental insights and technical details for utilizing biofunctional molecules that can form nanobiohybrid particles.

High-energy-pulse-electron beam (HEPE) has primarily been used in pulse radiolysis and material surface modification to date. In this study, we applied HEPE in yeast (Saccharomyces cerevisiae) breeding and investigated its biological effects on plasmid DNA and yeast plasma membrane. A thermo-tolerant and high- ethanol-yield yeast strain YE2 was obtained after HEPE radiation and temperature selection, with optimum temperature improved 2°C and ethanol yield improved 25.5%, suggesting that it is a promising candidate for cellulose-derived ethanol production. DNA-lesion analysis showed that the G-value of HEPE radiation for double-strand breaks (DSB) formation is 2.5 × 10−10 Gy−1 Da−1, which is 5 times that of γ-radiation, while there was only 12.1% plasma membrane damage found even at high dosage of 750 Gy.

Background & Aims: Expression of osteopontin correlates with tumor progression and metastasis. The mechanisms by which osteopontin promotes tumor cell survival remain unclear. Here we used short-hairpin RNA–mediated gene silencing to investigate the antitumor effects by osteopontin depletion in hepatocellular carcinoma (HCC). Methods: We applied polyethylenimine nanoparticles to deliver a short-hairpin RNA for depletion of osteopontin expression in HCC cells. Tumorigenicity and metastatic potentials of HCC cells were studied in vitro and in nude mice. Nuclear factor-κB (NF-κB) activation was analyzed by gel shift assay and luciferase analysis. The expressions of integrins were examined by real-time reverse-transcription polymerase chain reaction. Apoptosis was examined by terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling assay and mitochondrial membrane potential analysis. Results: Down-regulation of osteopontin inhibited HCC cell growth, anchorage-independent growth, adhesion with fibronectin and invasion through extracellular matrix in vitro, and suppressed tumorigenicity and lung metastasis in nude mice. Osteopontin silencing resulted in suppression of αv, β1, and β3 integrin expressions, blockade of NF-κB activation, inhibition of Bcl-2/Bcl-xL and XIAP expressions, increase of Bax expression, and induction of a mitochondria-mediated apoptosis. Furthermore, down-regulation of osteopontin inhibited drug-induced NF-κB activation and sensitized HCC cells to chemotherapeutic agents in vitro, which led to complete regression of HCC xenografts in nude mice. Conclusions: Osteopontin may facilitate tumorigenesis and metastasis through prevention of tumor cells from apoptosis. RNA interference–mediated depletion of osteopontin may be a promising strategy for the treatment of HCC by sensitizing the chemotherapeutic drugs.

Due to the nontoxicity and efficient anti-cancer activity, more and more attention has been paid to N-glycoside compounds. Laser photolysis of N-(α-D-glucopyranoside) salicyloyl hydrazine (NGSH) has been performed for the first time. The research results show that NGSH has high photosensitivity and is vulnerable to be photo-ionized via a monophotonic process with a quantum yield of 0.02, generating NGSH+· and hydrated electrons. Under the aerobic condition of cells, the hydrated electrons are very easy to combine with oxygen to generate 1O2 and O2−, both of which are powerful oxidants that can kill the cancer cells. In addition, NGSH+· can be changed into neutral radicals by deprotonation with a pKa value of 4.02 and its decay constant was determined to be 2.55×109dm3·mol−1·s−1. NGSH also can be oxidized by SO4−· with a rate constant of 1.76×109 dm3·mol−1·s−1, which further confirms the results of photoionization. All of these results suggest that this new N-glycoside compound might be useful for cancer treatment.

The impact of TiO2 nanoparticles on DNA synthesis in vitro in the dark and the molecular mechanism of such impact were studied. The impact of TiO2 nanoparticles on DNA synthesis was investigated by adding TiO2 nanoparticles in different sizes and at various concentrations into the polymerase chain reaction (PCR) system. TiO2 nanoparticles were premixed with the DNA polymerase, the primer or the template, respectively and then the supernatant and the precipitation of each mixture were added into the PCR system separately to observe the impact on DNA synthesis. Sequentially the interaction between TiO2 nanoparticles and the DNA polymerase, the primer or the template was further analyzed by using UV-visible spectroscopy and polyacrylamide gel electrophoresis (PAGE). The results suggest that TiO2 nanoparticles inhibit DNA synthesis in the PCR system in the dark more severely than microscale TiO2 particles at the equivalent concentration and the inhibition effect of TiO2 nanoparticles is concentration dependent. The molecular mechanism of such inhibition is that in the dark, TiO2 nanoparticles interact with the DNA polymerase through physical adsorption while TiO2 nanoparticles do with the primer or the template in a chemical adsorption manner. The disfunction levels of the bio-molecules under the impact of TiO2 nanoparticles are in the following order: the primer > the template > the DNA polymerase.

A new mesoporous support, hydrophilic polymer covering magnetic nanogels containing reactive carboxyl groups, was obtained by photochemical in situ polymerization. The enzyme α-chymotrypsin (CT), a model for protein or esters hydrolysis, was anchored to the support by 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide (EDC) activation. The immobilization proof was confirmed with Fourier transform spectroscopy (FT-IR) and transmission electron microscopy (TEM) observation. The bound CT behaved superparamagnetic and exhibited excellent response to applied magnetic field. The immobilized CT had better resistance to temperature and pH inactivation in comparison to the free form, and hence widened the reaction pH and temperature regions. Thermostability and storage stability of the enzyme increased up on covalent immobilization. The immobilized enzyme retained a relative activity of 85% after 12 repeated uses. Kinetic parameters were assayed for both free and immobilized CT. The value of K m (5.3 × 10 −4 M) for the immobilized enzyme was larger than that of the free counterpart (3.7 × 10 −4 M), while the V max (6.1 U mg −1 enzyme) was smaller for the immobilized enzyme.

To study the molecular mechanism of high mutation frequency induced by high-energy-pulse-electron (HEPE) beam radiation, the effects of HEPE radiation on yeast cells, plasma membrane, plasmid DNA, and protein activity were investigated by means of cell counting, gel electrophoresis, AO/EB double fluorescent staining, etc. The results showed that the viability of yeast cells declined statistically with increase of absorbed doses. The half lethal dose (LD50) was 134 Gy. HEPE beam radiation had little influence on the function of plasma membrane and protein, while it could induce much DNA damage of single strand breaks (SSB) and double strand breaks (DSB) that were required for gene mutation. The G-value for DSB formation of HEPE beam radiation in aqueous solution was 5.7 times higher than that caused by 60Co gamma rays. HEPE can be a new effective method for induced mutation breeding and deserves further research in the future.

The repair activities and reaction mechanisms of phenylpropanoid glycosides (PPGs) and their analogues, isolated from Chinese folk medicinal herbs, towards oxidative DNA damage were studied with pulse radiolytic technique. On pulse irradiation of nitrogen-saturated 4 mM poly C aqueous solution containing one of the tested polyphenols, 40 mM K2S2O8 and 200 mM t-BuOH, the transient absorption spectrum of the oxidative radical of poly C decays with the concurrent formation of the phenoxyl radical of the tested polyphenols within several tens of microseconds after the electron pulse irradiation. The result indicated that there was a repair reaction between oxidative radical of poly C and the tested polyphenols. The repair activities also were observed for the tested polyphenols towards the radical cations of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The rate constants were determined to be 3.7-6.4 x 10(9), 4.8-5.5 x 10(8) and 8.8-10.3 x 10(8) M(-1).sec(-1) for the repair reactions of oxidative radical of poly C and radical cations of ssDNA and dsDNA, respectively. The result of this study together with those of our previous studies demonstrates that PPGs and their analogues can fast repair not only the damage of deoxynucleoside and deoxynucleotide but also the damage of integral DNA, with the latter being closer to a cellular condition.

Reaction of p-tert-oxocalix[4]arene in acetonitrile (CH3CN) by 308nm laser pulses was investigated to understand its mechanism as polymer stabilizer. Four main absorption bands were observed at 300nm, 400nm, 460nm and 540nm. The 300nm absorption was assigned to the absorption of phenoxy radical, and the 460nm and 540nm were triple state absorption. It was concluded that the relative stable phenoxy radical mediate was formed through intramolecular energy transition of carbonyl triplet after laser excitation in CH3CN. The formation mechanism of phenoxyl radical was quite different from that in cyclohexane (C6H12), which was cooperation of two-photon process and one-photon process.

Photo-Fenton reaction was used to prepare polyethyleneimine nanogels (M-PEls) from PEI pre-polymer as potential non-viral gene delivery vectors. Competition between crosslinking and scission of PEI pre-polymer in assembled cluster made the size of particles homogeneous. Morphologies of the nanoparticles in every step showed the existence of self-assembly in aqueous solution. The results indicated that the crosslinking of PEI pre-polymer was mainly initiated via hydrogen abstraction by hydroxyl radicals generated in the systems. (c) 2007 Elsevier Ltd. All rights reserved.

Here we report transient spectral red-shift and transient absorption enhancement of p-benzoquinone radical in the presence of CdSe quantum dots after 355 nm pulse laser excitation. The spectral shift was caused by surface-bound p-benzoquinone molecules while the transient absorption increase was due to interfacial electron transfer from CdSe quantum dots to p-benzoquinone molecules. In contrast, spectral shift and absorption increase were much less significant for anthraquinone in the presence of CdSe quantum dots due to their weak adsorption abilities.

The performance of styrene–butadiene–styrene (SBS) triblock copolymer modified asphalt binder at high temperature can be improved significantly with the addition of SBS-g-M grafted with vinyl monomer under γ-rays irradiation. The dynamic mechanical properties of SBS modify asphalts binder before and after graft has been characterized by use of dynamic shear rheometer. It has been found that the added content of SBS-g-M has great effect on the rheological properties of the binder and its high temperature performance was improved while its temperature susceptibility was reduced in compare with SBS modified asphalts binder. It also has been confirmed that the morphology observed by fluorescence microscopy revealed the compatibility between SBS-g-M and asphalt and the storage stability of binder was improved significantly compared with SBS modified asphalt binder. As a consequence, the use of SBS grafted with polar monomer can be considered a suitable alternative for modification of binder in pavement.

TiO2 has been tested to be toxic to DNA under the photo-irradiation of ultraviolet A (UVA). However, in the dark conditions, after several days of treatment with TiO2 in aqueous solution, the interaction between TiO2 and two types of DNA was detected and the mechanisms were studied by the methods of gel-electrophoresis, IR spectroscopy and TEM. The results showed that the DNA would be bound to TiO2; the ratio of binding was related to the concentration and the treating time; the mechanism of binding is related to phosphate groups of DNA. Besides, DNA with different structure showed different degree of binding. These findings showed a new possible way through which the TiO2 nanoparticles interact with DNA.

A new aminated carrier—magnetic nanogels covered by amino groups, was obtained by Hoffman degradation of polyacrylamide-coated Fe3O4 nanoparticles prepared by photochemical polymerization. α-Chymotrypsin (CT) was covalently bound to the magnetic nanogels by use of 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide and N-hydroxysuccinimide at room temperature. Immobilization time, pH value of the reaction mixture and proportion of CT to the magnetic nanogels were investigated to obtain the optimum condition for CT immobilization. The maximal specific activity of the bound CT was determined to be 0.93 U/(mg min), 59.3% of free counterpart. The maximal binding capacity was measured to be 102 mg enzyme/g nanogel. Furthermore, the bound CT exhibited good thermal stability, storage stability and reusability.