Degradation of bisphenol A by <Emphasis Type="Italic">Bacillus pumilus</Emphasis> isolated from kimchi,a traditionally fermented food

Novel bisphenol A (BPA)-degrading bacterial strains, designated as BP-2CK, BP-21DK, and BP-22DK, were isolated from kimchi, a traditionally fermented food. These isolates were identified as Bacillus pumilus and efficiently degraded BPA in a medium supplemented with nutrients such as peptone, beef extract, and yeast extract. Strains BP-2CK, BP-21DK, and BP-22DK successfully degraded 25, 25, and 50 ppm of BPA, respectively, and all strains exhibited BPA-degrading activity in the presence of 10% NaCl. Accumulation of the metabolites including 4-hydroxyacetophenone, one of the intermediates produced by the other BPA-degrading bacteria, was not observed in BPA degradation by the isolated strains. These results indicate that the isolated food-derived bacteria are applicable for the construction of efficient and safer systems for the removal of BPA.     

Importance of control of enzymatic degradation for determination of bisphenol A from fruits and vegetables

The purpose of this study was to develop an analytical method for determination of bisphenol A (BPA) from fruits and vegetables. The present method developed for extraction of BPA from samples was based on solid-phase extraction (SPE) method and solvent extraction. Recovery results in the samples spiked with a 10 ng/ml BPA [no detection (<1 ng/g) to 77%] were lower than those in the samples with a 50 ng/ml BPA (26-96%). The fact that the low recovery results were caused by BPA degradation by enzymes is found. These problems were proved by the pH (pH ≤3) and the heating treatment (at ≥80 °C for 5 min). However, because the heating treatment at temperatures of ≥80 °C for 5 min is more difficult and time-consuming method than the pH control, we suggest that the pH control is useful to prevent BPA degradation. Good recovery results (82-101%) were obtained from all fruit and vegetable samples after pH treatment (pH ≤3). Effective elimination of impurities and a good detection limit (1 ng/g) were obtained with a method involving two SPE cartridges (OASIS HLB and Sep-Pak Florisil cartridge).     

Heterogeneous photodegradation of bisphenol A with iron oxides and oxalate in aqueous solution

To understand the degradation of endocrine disrupting chemicals (EDCs) with existence of iron oxides and polycarboxylic acids in the natural environment, the photodegradation of bisphenol A (BPA) at the interface of iron oxides under UV illumination was conducted. Four iron oxides were prepared by a hydrothermal process and then sintered at different temperatures of 65, 280, 310, and 420 degrees C named "IO-65," "IO-280," "IO-310," and "IO-420," respectively. The prepared iron oxides were characterized by X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) methods. The XRD pattern of IO-65 showed a crystal structure of lepidocrocite (gamma-FeOOH) and that of IO-420 demonstrated a crystal structure of hematite (alpha-Fe(2)O(3)), while IO-280 and IO-310 have the mixed crystal structures of maghemite (gamma-Fe(2)O(3)) and hematite. The BET results revealed that the specific surface areas decreased with the increase of sintering temperature. The results demonstrated that the photodegradation of BPA depends strongly on the properties of iron oxides and oxalate, and pH. The properties of iron oxides influenced strongly the dependence of the BPA degradation on the oxalate concentration. The optimal initial concentrations of oxalate for BPA degradation under UV illumination were determined to be 2.0, 2.0, 2.4, and 2.0 mM for IO-65, IO-280, IO-310, and IO-420, respectively. The first-order kinetic constants k for BPA degradation under UV illumination in the presence of oxalate with the optimal initial concentration are ranked as IO-280>IO-310>IO-65>IO-420. The experiments demonstrated that the optimal pH value should be in the range of 3-4. Furthermore, the dependence of BPA degradation should be also attributable to the formation of the dissolved Fe-oxalate in the solution and the adsorbed Fe-oxalate on the surface of iron oxides, and also the formation of hydrogen peroxide.     

Mesoporous Titania-Silica nanocomposite as an effective material for the degradation of Bisphenol A under visible light

A simple and very effective method is proposed for the removal of Bisphenol A (BPA) under visible light using mesoporous TiO₂-SiO₂ nanocomposite. The material was characterized using FTIR, XRD, DRS, XPS, FESEM, HRTEM, and BET techniques. The photo degradation efficiency of TiO₂-SiO₂ compared with bare TiO₂. The effect of calcination temperature on the photo-degradation of the materials is also studied. The radical intermediates formed during the degradation of BPA were followed with different radical scavengers. The solution after reaction is subjected to TOC (Total Organic Carbon content) and LCMS analysis to determine the mineralization rate and degradation products exist in the solution. Kinetic studies were revealed that the degradation process follow pseudo first order kinetics.     

Pyrolytic hydrolysis of polycarbonate in the presence of earth-alkali oxides and hydroxides

The rise in the use of polycarbonate (PC) calls for the development of after-use treatments. In this work, we describe a process for obtaining bisphenol A (BPA), phenol and isopropenyl phenol (IPP) from PC by hydrolysis at temperatures between 300 and 500 °C. The experiments were carried out in a steam atmosphere in the presence of MgO, CaO, Mg(OH)₂ or Ca(OH)₂ as catalysts, respectively. The results were compared with the hydrolysis of PC in the absence of any catalysts. All of these catalysts accelerated the hydrolysis of PC drastically, with MgO and Mg(OH)₂ being more effective than their Ca counterparts. The differences between oxides and hydroxides were negligible indicating the same mechanism for both, oxides and hydroxides. BPA was the main product at 300 °C, with a yield of 78% obtained in the presence of MgO. At 500 °C, BPA was mainly degraded to phenol and isopropenyl phenol (IPP). It can be shown that a combined process involving PC hydrolysis at 300 °C and BPA fission at 500 °C leads to high yields of phenol and IPP and the drastic decrease of residue.     

Analysis of metallothioneins by means of capillary electrophoresis coupled to electrospray mass spectrometry with sheathless interfacing

Capillary electrophoresis (CE) coupled to electrospray mass spectrometry via sheathless interfacing has been applied to the analysis of mammalian metallothionein (MT) extracts. In a rabbit-liver extract, four (MT-2C, MT-2A, MT-2D and MT-2E) out of six known MT sub-isoforms were unambiguously identified under three CE-resolved peaks. A fourth peak was found to contain MT-1A and/or MT-2B, whose molecular masses differ by only 1 Da. Traces of non-N-acetylated MT-2D and MT-2E were observed in a fifth, minor peak. In a rat-liver extract, both MT-1 and MT-2 were resolved and identified. Non-N-acetylated MT-2 was also identified in a resolved, minor peak. Minimum detectable amounts of MTs have been estimated to be approximately 0.6 fmol per sub-isoform.     

载钛羟基磷灰石光催化降解内分泌干扰物双酚A

对载钛羟基磷灰石（TiHAP）进行了透射电镜、X射线衍射、紫外-可见光谱和Zeta电位表征,并应用液相色谱-质谱技术对比了TiHAP和P25 TiO₂对环境内分泌干扰物双酚A（BPA）的吸附和光催化降解性能,探讨了富里酸和Fe³⁺对TiHAP薄膜光催化性能的影响。结果表明,TiHAP和TiO₂粉体对BPA的吸附符合Langmuir吸附等温方程,且前者吸附性能更大。TiHAP薄膜光催化降解BPA的性能优于TiO₂薄膜;富里酸和Fe³⁺对TiHAP和TiO₂薄膜光催化性能的影响趋势不同,从能带结构、电子转移和吸光性等角度分析了性能不同的原因。本结果可以为应用TiHAP降解环境内分泌干扰物提供依据。     

Study on depolymerization of polycarbonate in supercritical ethanol

The characteristics of depolymerization of PC in supercritical ethanol were investigated in the range of 483-563 K by using a high-pressure batch autoclave reactor. Based on the qualitative and quantitative analyses of the products, a depolymerization-reaction model was proposed to explain the reaction mechanism, i.e. random scission and ester exchange reaction occurred simultaneously during the process of depolymerizaition of PC. It was suggested that the process of depolymerization consisted of subcritical region, transitional region and supercritical region. It was indicated that PC degraded with slow decrease of molecular weight determined by GPC and with the conversion of 7.5% at 513 K in subcritical region. While in the supercritical region, the molecular weight of PC decreased quickly and degraded completely in 30 min at 563 K. Continuous-distribution kinetics could be used to describe the mechanism of polymer degradation and the energy of activation for the random scission of PC in the supercritical region was 97.2 kJ/mol. Moreover, PC could be degraded completely into diethyl carbonate (DEC) and bisphenol A (BPA) with the yields of 89% and 90%, respectively, in supercritical region.     

Degradation of Triclosan under Aerobic, Anoxic, and Anaerobic Conditions

Triclosan (2, 4, 4??-trichloro-2??-hydroxyl diphenyl ether) is a broad-spectrum antimicrobial agent present in a number of house hold consumables. Aerobic and anaerobic enrichment cultures tolerating triclosan were developed and 77 bacterial strains tolerating triclosan at different levels were isolated from different inoculum sources. Biodegradation of triclosan under aerobic, anoxic (denitrifying and sulphate reducing conditions), and anaerobic conditions was studied in batch cultures with isolated pure strains and enrichment consortium developed. Under aerobic conditions, the isolated strains tolerated triclosan up to 1?g/L and degraded the compound in inorganic-mineral-broth and agar media. At 10?mg/L level triclosan, 95?±?1.2% was degraded in 5?days, producing phenol, catechol and 2, 4-dichlorophenol as the degradation products. The strains were able to metabolize triclosan and its degradation products in the presence of monooxygenase inhibitor 1-pentyne. Under anoxic/anaerobic conditions highest degradation (87%) was observed in methanogenic system with acetate as co-substrate and phenol, catechol, and 2, 4-dichlorophenol were among the products. Three of the isolated strains tolerating 1?g/L triclosan were identified as Pseudomonas sp. (BDC 1, 2, and 3).     

Controllable Synthesis of BiOCl with Z-Scheme (001)/(110) Facet Homojunction and their Photocatalytic Killing Effect on HePG2 Cells in vitro

In this study, a set of BiOCl with controllable ratios of (001) and (110) facets was prepared by adjusting the content of diethylene glycol (DEG) during the preparation process. The degradation experiment of bisphenol A (BPA) shows that under simulated sunlight, when the ratio of (001) to (110) is 0.61, BiOCl (BOC-2) has the best degradation activity, which can degrade 96.2% BPA within 20 min. After theoretical calculations and experimental characterization, a Z-scheme (001)/(110) facet homojunction is proposed. Then, three typical samples were selected to test the biological toxicity of HepG2 cells and the activity of killing HepG2 cells under ultraviolet light conditions. Studies have found that exposed facets play a more important role in the biotoxicity of BiOCl to cells; with a (001)/(110) ratio of 0.61, BOC-2 exhibits excellent endocytosis and phototoxicity but no obvious dark cytotoxicity, while with a (001)/(110) ratio of 0.15, BiOCl (BOC-4) has poor endocytosis and strong cytotoxicity under dark conditions. Through reactive oxygen species (ROS) and lactate dehydrogenase (LDH) assay detection, the process of photocatalytic killing cells of BOC-2 more looks like an apoptosis mechanism, while BOC-4 mainly causes cell necrosis.     

Enhancement of oxygen vacancies and solar photocatalytic activity of zinc oxide by incorporation of nonmetal

B-doped ZnO and N-doped ZnO powders have been synthesized by mechanochemical method and characterized by TG-DTA, XRD, SEM-EDX, XPS, UV-visible and photoluminescence (PL) spectra. X-ray diffraction data suggests the hexagonal wurtzite structure for modified ZnO crystallites and the incorporation of nonmetal expands the lattice constants of ZnO. The room temperature PL spectra suggest more number of oxygen vacancies exist in nonmetal-doped ZnO than that of undoped zinc oxide. XPS analysis shows the substitution of some of the O atoms of ZnO by nonmetal atoms. Solar photocatalytic activity of B-doped ZnO, N-doped ZnO and undoped ZnO was compared by means of oxidative photocatalytic degradation (PCD) of Bisphenol A (BPA). B-doped ZnO showed better solar PCD efficiency as compare to N-doped ZnO and undoped ZnO. The PCD of BPA follows first order reaction kinetics. The detail mechanism of PCD of Bisphenol A was proposed with the identification of intermediates such as hydroquinone, benzene-1,2,4-triol and 4-(2-hydroxypropan-2-yl) phenol.     

基于薄层反应器的有机污染物光电催化氧化反应性能与机理

基于薄层反应器快速耗竭氧化特点,研究了典型环境内分泌干扰物双酚A在TiO2纳米管阵列电极上的光电催化氧化反应性能与反应机理.结果表明,薄层反应器中光电流、初始峰值电流、耗竭反应净电量和空白光电流等光电催化物理参数均能反映光电催化反应速率,并适用于催化反应的机制分析.峰值光电流与双酚A初始浓度拟合结果表明,双酚A在电极表...     

Ag-single atoms modified S1.66-N1.91/TiO2-x for photocatalytic activation of peroxymonosulfate for bisphenol A degradation

In this study,Ag_0.23/(S_1.66-N_1.91/TiO_2-x) single-atom photocatalyst was synthesized by in-situ photoreducing of silver on S,N-TiO_2-x nanocomposite and used to degrade bisphenol A（BPA） through heterogeneous activation of potassium peroxymonosulfate（PMS） under visible-light illumination.The structure,physicochemical property,morphology,and electronic property were evalutated by X-ray diffraction（XRD）,Raman spectrum,X-ray photoelectron spectra（...     

Ionic liquid-assisted synthesis of defect-rich BiOI with controllable structure and high surface area for excellent visible-light photocatalytic activity

In this study, BiOI materials with controllable structure are designed by using ionic liquid as I source and template to create the surface oxygen defects, thus promoting the photogenerated carrier migration and enhancing the photocatalytic activity. The texture of BiOI is controlled by adjusting the pH values of reaction mixture and the corresponding formation mechanism is also explored based on the self-assembly behavior of ionic liquid. It is found that the sample BiOI-7 possesses the ultrathin nanosheets (2 ~ 4 nm) and abundant surface oxygen defects which are beneficial for accelerating carrier transfer and facilitating photocatalytic degradation. The photocatalytic activity of as-prepared BiOI is studied by using Rhodamine B (RhB), methyl orange (MO) and Bisphenol A (BPA) as target pollutants, respectively. Besides, water splitting reactions were also used to further check the photocatalytic activity. BiOI samples exhibit the enhanced photocatalytic activity than bulk BiOI and g-C₃N₄ obtained by calcination of melamine. Especially, 92% of bisphenol A (BPA) can be degraded under light irradiation within 1 hr by using only 5 mg of BiOI-7 nanosheets, which is superior than most counterparts reported so far. This rapidly synthetic route can be applied in fabrication of other novel materials with diverse morphology and porous structure.     

Evaluation of a dry, rehydratable film method for rapid enumeration of Staphylococcus aureus

Results with the new 3M Petrifilm Rapid S. aureus Count (RSA) Plate method were compared with those of the classical Baird-Parker agar (BPA) method for detection and enumeration of Staphylococcus aureus. Studies on 219 bacterial strains demonstrated that the Petrifilm RSA plate is more sensitive than and as specific as the classical BPA method for confirmed identification of S. aureus. Counts of colonies from 71 pure cultures, 61 naturally contaminated food samples, and more than 750 artificially inoculated food samples showed that the Petrifilm RSA method was as effective as the classical BPA method for identification and enumeration of S. aureus. The Petrifilm RSA method gave results in one-third the time required for the classical method.     

Antimicrobial activity and protease stability of peptides containing fluorinated amino acids

Selective fluorination of peptides results in increased chemical and thermal stability with simultaneously enhanced hydrophobicity. We demonstrate here that fluorinated derivatives of two host defense antimicrobial peptides, buforin and magainin, display moderately better protease stability while retaining, or exhibiting significantly increased bacteriostatic activity. Four fluorinated analogues in the buforin and two in the magainin series were prepared and analyzed for (1) their ability to resist hydrolytic cleavage by trypsin; (2) their antimicrobial activity against both gram-positive and gram-negative bacterial strains; and (3) their hemolytic activity. All but one fluorinated peptide (M2F5) showed retention, or significant enhancement, of antimicrobial activity. The peptides also showed modest increases in protease resistance, relative to the parent peptides. Only one of the six fluorinated peptides (BII1F2) was degraded by trypsin at a slightly faster rate than the parent peptide. Hemolytic activity of peptides in the buforin series was essentially null, while fluorinated magainin analogues displayed an increase in hemolysis compared to the parent peptides. These results suggest that fluorination may be an effective strategy to increase the stability of biologically active peptides where proteolytic degradation limits therapeutic value.     

Effect of novel compatibilizers on the properties and morphology of PP/PC blends

A series of compatibilizers, including polypropylene (PP) grafted with 2‐tertbutyl‐6‐(3‐tertbutyl‐ 2‐hydroxy‐5‐methylbenzyl)‐4‐methylphenyl acrylic ester (BPA), glycidyl methacrylate (GMA), GMA/styrene (GMA‐st), and 2‐allyl bisphenol A (2A) were investigated for the purpose of improving the compatibility of PP/polycarbonate (PC) blends. PP‐g‐BPA shows a remarkable compatibilizing effect on PP/PC blends since it has similar group‐benzene ring with PC, and it is a sort of heat‐resistant antioxidant in the meantime, which can reduce the molecular degradation of PP during grafting and blending under high temperatures. Its compatibilizing effect was examined in terms of the mechanical, thermal properties, and morphologies. PP/PC blends show a decreasing and much more homogeneous size of dispersed PC particles through addition of a small amount of PP‐g‐BPA, and dynamic mechanical analysis (DMA) reveals a noticeable approach of T_g between PP and PC, indicating the improvement of the compatibility of PP/PC blends. Furthermore, styrene‐ethylene‐butylene‐styrene (SEBS) as a toughening rubber and a compatibilizer was applied to PP/PC blends. Around 25 wt% SEBS and 20 wt% PC lead to high toughness and strength of PP. Copyright © 2008 John Wiley & Sons, Ltd.     

大体积样品堆积-毛细管电泳-紫外检测分析鼠肝中不同亚型金属硫蛋白

制备了均匀稳定的聚丙烯酰胺涂层毛细管,有效抑制了毛细管内壁对金属硫蛋白(MT)的吸附,大大提高了MT的分离度和分离重现性。基于此,建立了大体积样品堆积-毛细管电泳-紫外检测法(LVSS-CE-UV)分析鼠肝中MT的新方法。在最优化的条件下,该方法对两种MT亚型(MT-1/2)的富集倍数分别为13、11倍,检出限分别为0.80、1.01μg·m L~(-1)。将所建立的LVSS-CE-UV方法用于经Cd~(2+)、Zn~(2+)诱导的Sprague Dawley大鼠肝脏中MT-1/2的定量分析,结果表明经Cd~(2+)、Zn~(2+)诱导的鼠肝内均检测出MT-1/2。其中,经Zn~(2+)诱导的鼠肝内MT-1与MT-2的含量分别为31.9、24.3μg·g~(-1);Cd~(2+)诱导组的MT-1与MT-2分别为15.9、31.2μg·g~(-1)。     

Biocompatible inorganic nanoparticles for [18F]-fluoride binding with applications in PET imaging

A wide selection of insoluble nanoparticulate metal salts was screened for avid binding of [(18)F]-fluoride. Hydroxyapatite and aluminium hydroxide nanoparticles showed particularly avid and stable binding of [(18)F]-fluoride in various biological media. The in vivo behaviour of the [(18)F]-labelled hydroxyapatite and aluminium hydroxide particles was determined by PET-CT imaging in mice. [(18)F]-labelled hydroxyapatite was stable in circulation and when trapped in various tissues (lung embolisation, Subcutaneous and intramuscular), but accumulation in liver via reticuloendothelial clearance was followed by gradual degradation and release of [(18)F]-fluoride (over a period of 4 h) which accumulated in bone. [(18)F]-labelled aluminium hydroxide was also cleared to liver and spleen but degraded slightly even without liver uptake (Subcutaneous and intramuscular). Both materials have properties that are an attractive basis for the design of molecular targeted PET imaging agents labelled with (18)F.     

An Electrochemical Sensor Based on Nitrogen‐doped Carbon Nanofiber for Bisphenol A Determination

In this paper, bisphenol A was determined by electrochemical method at a nitrogen‐doped carbon nanofiber modified carbon paste electrode (NCNF/CPE) with high sensitivity and good selectivity. NCNF was obtained by a simple electrospinning followed by carbonization procedure, in which polyacrylonitrile (PAN) as precursor and nitrogen doping was realized by re‐utilizing the tail gas that produced in the thermal pretreatment process. Good reproducibility and high stability were obtained for BPA detection at NCNF modified CPE. Current response plotted with BPA concentration was linear in the range of 0.1–60 μM with LOD of 0.05 μM. The proposed electrochemical sensor was employed for BPA determination with satisfactory recoveries for real water samples, indicating the practical applicability of NCNF/CPE.