Experimental study on the inhibition of biological reduction of Fe(Ⅲ)EDTA in NOx absorption solution

Scrubbing of NOx from the gas phase with Fe(Ⅱ)EDTA has been shown to be highly effective. A new biological method can be used to convert NO to N2 and regenerate the chelating agent Fe(Ⅱ)EDTA for continuous NO absorption. The core of this biological regeneration is how to effectively simultaneous reduce Fe(Ⅲ)EDTA and Fe(Ⅱ)EDTA-NO, two mainly products in the ferrous chelate absorption solution. The biological reduction rate of Fe(Ⅲ)EDTA plays a main role for the NOx removal efficiency. In this paper, a bacterial strain identified as Klebsiella Trevisan sp. was used to demonstrate an inhibition of Fe(Ⅲ)EDTA reduction in the presence of Fe(Ⅱ)EDTA-NO. The competitive inhibition experiments indicted that Fe(Ⅱ)EDTA-NO inhibited not only the growth rate of the iron-reduction bacterial strain but also the Fe(Ⅲ)EDTA reduction rate. Cell growth rate and Fe(Ⅲ)EDTA reduction rate decreased with increasing Fe(Ⅱ)EDTA-NO concentration in the solution.     

Absorption of NO2 into Na2S solution in a stirred tank reactor

To understand the absorption mechanism of nitrogen dioxide into a sodium sulfide solution, a stirred tank reactor with a plane gas-liquid interface was used to measure the chemical absorption rate of diluted nitrogen dioxide into sodium sulfide solution. The absorption rates under various experimental conditions were measured and the effects of experimental conditions on nitrogen dioxide absorption rate were discussed. The results show that, in the range of this study, nitrogen dioxide absorption rate increases with increasing sodium sulfide concentration, nitrogen dioxide inlet concentration, and flue gas flow rate, but decreases with increasing reaction temperature and oxygen content in flue gas.     

Characterization of Aquabacterium parvum sp. Strain B6 during Nitrate-Dependent Fe(Ⅱ) Oxidation Batch Cultivation with Various Impact Factors

In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(Ⅱ) oxidation,batch cultivation was conducted, and its ability to oxidize Fe(Ⅱ) coupled to nitrate reduction in the presence of diverse organic substrates was studied. Meanwhile, the nitrate-removal rate of B6 with various impact factors was further optimized by the response surface methodology(RSM). The results show that strain B6 is capable of utilizing different organic compounds as substrates for nitrate reduction. Compared with yeast extract, B6 showed a greater potential of chemical oxygen demand(COD)degradation and cell proliferation with acetate and glucose mediums, respectively, while citrate was not beneficial for this process due to its low consumption rate. RSM analysis demonstrated that the maximum nitrate-reduction rate of 30.64% could be achieved with an initial pH of 7.4,incubation temperature of 25.0 °C, and carbon source concentration of 266.10 mg/L.     

Methanethiol Removal from Biogas by Biological Conversion in an Anaerobic Biotrickling Filter

In this study, methanethiol(MT)-degradation bacteria were cultivated by using MT, methanol and trimethylamine as carbon sources under anaerobic conditions. It was found that the batch bacteria used MT and methanol as carbon sources grew faster than those used trimethylamine. The enriched bacteria used MT and methanol as the carbon sources were respectively inoculated in different biotrickling filters. The biological conversion performance of MT under anaerobic conditions was investigated in biotrickling filters. The results showed that the performance of the biotrickling filter inoculated with the bacteria enriched using MT was better than that inoculated with the bacteria enriched using methanol. When the inlet concentration of MT was 0.005vol%(50,ppm), the empty bed residence time was 50 s, p H value was 8.0, and the flow rate of the nutrient solution was 10 L/h, the removal efficiency of MT reached 95.3%. Adding methanol stimulated the growth of the biomass and the degradation of MT, but caused that some bacteria only degrading methanol outcompeted the bacteria only degrading MT. The concentration of sodium bicarbonate in the nutrient solution needed to be controlled lower than 30 g/L, otherwise, it would be harmful to the degradation of MT.     

Availability and toxicity of Fe(Ⅱ) and Fe(Ⅲ) in Caco-2 cells

The objective of the present study was to compare the toxicity and availability of Fe(Ⅱ) and Fe(Ⅲ) to Caco-2 cells.Cellular damage was studied by measuring cell proliferation and lactate dehydrogenase (LDH) release. The activities of two major antioxidative enzymes [superoxide dismutase (SOD) and glutathione peroxidase (GPx)] and differentiation marker (alkaline phosphatase) were determined after the cells were exposed to different levels of iron salts. The cellular iron concentration was investigated to evaluate iron bioavailability. The results show that iron uptake of the cells treated with Fe(Ⅱ) is significantly higher than that of the cells treated with Fe(Ⅲ) (P＜0.05). Fe(Ⅱ) at a concentration>1.5 mmol/L was found to be more effective in reducing cellular viability than Fe(Ⅲ). LDH release investigation suggests that Fe(Ⅱ) can reduce stability of the cell membrane. The activities of SOD and GPx of the cells treated with Fe(Ⅱ) were higher than those of the cells treated with Fe(Ⅲ), although both of them increased with raising iron supply levels. The results indicate that both Fe(Ⅱ) and Fe(Ⅲ) could reduce the cellular antioxidase gene expression at high levels.     

Mechanism of action of two insect toxins huwentoxin-Ⅲ and hainantoxin-Ⅵ on voltage-gated sodium channels

Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI),were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography(RP-HPLC).The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels(VGSCs) was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median(DUM) neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons(concentration of toxin at half-maximal inhibition(IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin(TTX).HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.     

The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe3 ) dosage. The existence of a critical pH value determining the catalysis of Fe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.     

Numerical Derivation of Strain Rate Effects on Material Properties of Masonry with Solid Clay Bricks

In this paper, numerical method is used to study the strain rate effect on masonry materials. A typical unit of masonry is selected to serve as a representative volume element (RVE). Numerical model of RVE is established with detailed distinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor (DIF) of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results.     

Investigation and evaluation of ultrasound reactor for reduction of fungi from sewage

The objective of the investigation was to study the application of ultrasound reactor technology （USRT） as a disinfectant for reduction of fungi from sewage effluent. Fungi are carbon heterotrophs that require preformed organic compounds as carbon sources. USRT is an attractive means to improve water quality because of the system simplicity and no production of toxic by-products. An ultrasound reactor produces strong cavitation in aqueous solution causing shock waves and reactive free radicals by the violent collapse of the cavitation bubble. These effects should contribute to the physical disruption of microbial structures and inactivation of organisms. There was significant reduction in fungal growth, with decreased fungal growth with increasing USRT. In this study, ultrasound irradiation at a frequency of 42 kHz was used to expose suspensions of fungi to evaluate the disinfection efficacy of the ultrasound reactor. Also, this study showed that in this system more than 99% reduction of sewage fungi was achieved after 60 min.     

Gold Nanoparticles of Multiple Shapes Synthesized in L-Tryptophan Aqueous Solution

In this paper, we describe a simple and efficient synthesis of gold nanoparticles(GNPs) of various shapes(spherical, rod-like, hexagonal, truncated triangular, and triangular) using Au(Ⅲ) reduction in aqueous solutions by L-tryptophan. We evaluated the influences of reaction temperature, foreign metal ions Ag(Ⅰ), and surfactants of nonionic(polyethylene glycol, PEG), anionic(sodium dodecyl sulfate, SDS), and cationic(cetyltrimethyl ammonium bromide, CTAB) on GNPs synthesis. We characterized the resultant GNPs using UV–visible adsorption spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, selected-area electron diffraction, and Fourier-transform infrared spectroscopy. We fabricated the variously sized GNPs by controlling the rate of the reduction of gold ions in aqueous solution by varying the reaction temperature: the higher the temperature, the smaller the gold nanospheres. We found the existence of Ag(Ⅰ) to reinforce the reduction of Au(Ⅲ) and to correspond with the appearance of some amorphous bimetallic Au/Ag nanoparticles. Additionally, we found the presence of surfactants to greatly influence the shape of the formed GNPs, especially the presence of CTAB, which results in the anisotropic growth of gold nanocrystals into hexagonal, truncated triangular, and triangular nanoplates. In addition, with the increase in CTAB concentration, we found the amount of gold nanoplates to first increase and then decrease. Finally, we performed preliminary explorations of the reduction process and morphological evolution to propose possible corresponding reduction and morphological evolution pathways.     

Science Letters：Nitrogen doping of activated carbon loading Fe2O3 and activity in carbon-nitric oxide reaction

Nitrogen doping of activated carbon loading Fe2O3 was performed by annealing in ammonia, and the activity of the modified carbon for NO reduction was studied in the presence of oxygen. Results show that Fe2O3 enhances the amount of surface oxygen complexes and facilitates nitrogen incorporation in the carbon, especially in the form of pyridinic nitrogen. The modified carbon shows excellent activity for NO reduction in the low temperature regime (<500 °C) because of the cooperative effect of Fe2O3 and the surface nitrogen species.     

Numerical Derivation of Strain Rate Effects on Material Properties of Masonry with Solid Clay Bricks

In this paper, numerical method is used als. A typical unit of masonry is selected to serve merical model of RVE is established with detailed to study the strain rate effect on masonry materias a representative volume element （RVE）. Nudistinctive modeling of brick and mortar with their respective dynamic material properties obtained from laboratory tests. The behavior of brick and mortar are characterized by a dynamic damage model that accounts for rate-sensitive and pressuredependent properties of masonry materials. Dynamic loads of different loading rates are applied to RVE. The equivalent homogenized uniaxial compressive strength, threshold strain and elastic modulus in three directions of the masonry are derived from the simulated responses of the RVE. The strain rate effect on the masonry material with clay brick and mortar, such as the dynamic increase factor （DIF） of the ultimate strength and elastic modulus as a function of strain rate are derived from the numerical results.     

Catalytic dechlorination and detoxification of 1-（2-chlorophenyl） ethanol by Pd/Fe

1-（2-chlorophenyl） ethanol （CPE） is of health and environmental concern due to its toxicity and its use as an intermediate in pharmaceutical manufacturing. The current work deals with the catalytic reductive dechlorination and detoxification of CPE by Pd/Fe bimetal. CPE was effectively dechlorinated to l-phenyl ethanol （PE） accompanied by the equivalent release of chloride. The extent of CPE dechlorination increased with temperature, Fe dosage and Pd loading. A decrease in solution pH increased CPE dechlorination, resulting presumably from an increase in hydrogen production. Under the specific conditions of 20 g/L Pd/Fe, 0.10% Pd （w/w） and initial pH 5-6, the CPE dechlorination was completed within 145 rain. The dechlorination followed a pseudo-first-order kinetics with an activation energy of 56.7 kJ/mol. The results of toxicity testing showed that CPE was very toxic to Chlorella, whereas PE showed little toxicity. The toxicity of the reaction solution declined gradually and the promoting effects on Chlorella intensified consequently with the dechlorination process. Thus, the reductive dechlorination of CPE to PE by Pd/Fe was a detoxification process. It may be used to effectively reduce the toxicological effects of CPE-contaminated wastewater, thereby enhancing the performance of subsequent biological processes in wastewater treatment.     

Microstructure and hardness of Cu-12% Fe composite at different drawing strains简

Cu-12% Fe （in weight） composite was prepared by casting, pretreating, and cold drawing. The microstructure was observed and Vickers hardness was measured for the composite at various drawing strains. Cu and Fe grains could evolve into aligned filaments during the drawing process. X-ray diffraction （XRD） was used to analyze the orientation evolution during the drawing process. The axial direction of the filamentary structure has different preferred orientations from the radial directions. The strain of Fe grains linearly increases with an increase in the drawing strain up to 6.0, and deviates from the linear relation when the drawing strain is higher than 6.0. With an increase in the drawing strain, the microstructure scales of Fe filaments exponentially decrease. The density of the interface between Cu and Fe phases exponentially increases with an increase in the aspect ratio of Fe filaments. There is a similar Hall-Perch relationship between the hardness and Fe filament spacing. The refined microstructure from drawing deformation at drawing strains lower than 3.0 can induce a more significant hardening effect than that at drawing strains higher than 3.0.     

Rate-dependent constitutive model of poly（ethylene terephthalate） for dynamic analysis

Uniaxial tensile testing at strain rates ranging from 10-3 to 10-1 s-1 was carried out to study the rate-dependent me-chanical behavior for poly（ethylene terephthalate） （PET） used in the packaging industry. The experimental results show that a rate-dependent plastic behavior exists for PET material. The value of the yield strength was found to increase with the increasing strain rate. A new constitutive model based on the improved Cowper-Symonds rate-dependent constitutive model is proposed to describe the mechanical behavior of PET material in the strain rate ranging from 10-3 to 10-1 s-1, providing more accurate material data for the subsequent simulation analysis of drop test and dynamic buckling. The predictions obtained using the proposed model are compared with experimental results of the improved Cowper-Symonds model. The simulating results of the proposed model agree well with the experimental data. For a low strain rate, the predictions of this model are more precise than those obtained using the improved Cowper-Symonds model. This confirms that the new constitutive model is suitable for describing the me-chanical behavior of PET material at a low strain rate and modeling impact problem.     

Strain Growth in Containment Vessels

Strain growth is a phenomenon observed in containment vessels subjected to internal blast loading. The elastic response of the vessel may become larger in a later stage compared to its response during the initial stage. The dynamic responses of infinitely long cylindrical containment vessels subjected to uniformly-distributed internal blast loading are studied using LS-DYNA. The development of bending modes and the interaction between the breathing mode and bending modes are observed. The methodology developed for dynamic elastic buckling analysis is employed to study the strain growth phenomenon in explosion containment vessels. It is shown that the dynamic instable vibration of a containment vessel is the basic mechanism of strain growth.     

Enhanced production of elastase by Bacillus licheniformis ZJUEL31410： optimization of cultivation conditions using response surface methodology

Sequential methodology based on the application of three types of experimental designs was used to optimize the fermentation conditions for elastase production from mutant strain ZJUEL31410 of Bacillus licheniformis in shaking flask cul- tures. The optimal cultivation conditions stimulating the maximal elastase production consist of 220 r/min shaking speed, 25 h fermentation time, 5% (v/v) inoculums volume, 25 ml medium volume in 250 ml Erlenmeyer flask and 18 h seed age. Under the optimized conditions, the predicted maximal elastase activity was 495 U/ml. The application of response surface methodology resulted in a significant enhancement in elastase production. The effects of other factors such as elastin and the growth factor (corn steep flour) on elastase production and cell growth were also investigated in the current study. The elastin had no significant effect on enzyme-improved production. It is still not clear whether the elastin plays a role as a nitrogen source or not. Corn steep flour was verified to be the best and required factor for elastase production and cell growth by Bacillus licheniformis ZJUEL31410.     

Magnetic Properties of Nanocrystalline Fe60Cr40 Powders Prepared by Mechanical Alloying in Vacuum and Air

Magnetic properties of nanocrystalline Fe60 Cr40 powders prepared by mechanical alloying in vacuum and air were investigated by utilizing the measurements of magnetization, X-ray diffraction, and ^67Fe M（oe）ssbauer spectrum. The results show that the Fe60 Cr40 powders keep the bcc structure during milling in air and vacuum. The saturation magnetization of the Fe60 Cr40 powders milled in vacuum and air decreases with the increase of the milling time up to 45 h. The decrease of saturation magnetization of the Fe60Cr40 powders milled in vacuum is due to the formation of Fe-Cr solid solution, while in air it is due to the formation of paramagnetic disorder structure and solid solution.     

Passivity Degradation of Alloy 800 in Simulated Crevice Chemistries

Passivity degradation of Alloy 800 in simulated crevice chemistries was systematically investigated using cyclic polarization curve, electrochemical impedance spectroscopy(EIS), Mott-Schottky analysis, Auger electron spectroscopy(AES)and atomic absorption spectrometry(AAS). Cyclic polarization showed that the pitting potential in a thiosulfate solution was much lower than in either a chloride solution or a sulfate-chloride solution. Mott-Schottky results revealed that passive films showed n-type semiconductivity, and the presence of thiosulfate in chloride solution led to an increased donor density in the passive film. EIS spectra indicated that thiosulfate enhanced the film dissolution rate in chloride solutions. Moreover, thiosulfate enhanced the pitting propagation rate in chloride solution by stabilizing the metastable pits and forming sulfide within the pits.