How does the biochar-supported sulfidized nanoscale zero-valent iron affect the soil environment and microorganisms while remediating cadmium contaminated paddy soil?

In previous studies, iron-based nanomaterials, especially biochar (BC)-supported sulfidized nanoscale zero-valent iron (S-nZVI/BC), have been widely used for the remediation of soil contaminants. However, its potential risks to the soil ecological environment are still unknown. This study aims to explore the effects of 3% added S-nZVI/BC on soil environment and microorganisms during the remediation of Cd contaminated yellow-brown soil of paddy field. The results showed that after 49 d of incubation, S-nZVI/BC significantly reduced physiologically based extraction test (PBET) extractable Cd concentration (P < 0.05), and increased the immobilization efficiency of Cd by 16.51% and 17.43% compared with S-nZVI and nZVI/BC alone, respectively. Meanwhile, the application of S-nZVI/BC significantly increased soil urease and sucrase activities by 0.153 and 0.446 times, respectively (P < 0.05), improving the soil environmental quality and promoting the soil nitrogen cycle and carbon cycle. The results from the analysis of the 16S rRNA genes indicated that S-nZVI/BC treatment had a minimal effect on the bacterial community and did not appreciably alter the species of the original dominant bacterial phylum. Importantly, compared to other iron-based nanomaterials, incorporating S-nZVI/BC significantly increased the soil organic carbon (OC) content and decreased the excessive release of iron (P < 0.05). This study also found a significant negative correlation between OC content and Fe(II) content (P < 0.05). It might originate from the reducing effect of Fe-reducing bacteria, which consumed OC to promote the reduction of Fe(III). Accompanying this process, the redistribution of Cd and Fe mineral phases in the soil as well as the generation of secondary Fe(II) minerals facilitated Cd immobilization. Overall, S-nZVI/BC could effectively reduce the bioavailability of Cd, increase soil nutrients and enzyme activities, with less toxic impacts on the soil microorganisms.

Phthalate and DINCH exposure and ovarian reserve markers among women seeking infertility care.

Phthalate exposure can adversely impact ovarian reserve, yet investigation on the influence of its alternative substance, the non-phthalate plasticizer diisononyl-cyclohexane-1,2-dicarboxylate (DINCH), on ovarian reserve is very sparce. We aimed to investigate the associations of phthalate and DINCH exposure as well as their combined mixture with ovarian reserve. This present study included 657 women seeking infertility care in Jiangsu, China (2015-2018). Urine samples during enrollment prior to infertility treatment were analyzed using high-performance liquid chromatography-isotope dilution tandem mass spectrometry (UPLC-MS/MS) to quantify 17 phthalate metabolites and 3 DINCH metabolites. Multivariate linear regression models, Poisson regression models and weighted quantile sum (WQS) regression were performed to access the associations of 17 urinary phthalate metabolites and 3 DINCH metabolites with ovarian reserve markers, including antral follicle count (AFC), anti-Mullerian hormone (AMH), and follicle-stimulating hormone (FSH). We found that the most conventional phthalates metabolites (DMP, DnBP, DiBP, DBP and DEHP) were inversely associated with AFC, and the DINCH metabolites were positively associated with serum FSH levels. The WQS index of phthalate and DINCH mixtures was inversely associated with AFC (% change = -8.56, 95 % CI: -12.63, -4.31) and positively associated with FSH levels (% change =7.71, 95 % CI: 0.21, 15.78). Our findings suggest that exposure to environmental levels of phthalate and DINCH mixtures is inversely associated with ovarian reserve.

High performance self-assembled sulfidized nanoscale zero-valent iron for the immobilization of cadmium in contaminated sediments: Optimization, microbial response, and mechanisms.

Sulfidized nanoscale zero-valent iron (S-nZVI) showed excellent removal capacity for cadmium (Cd) in aqueous phase. However, the remediation effects of S-nZVI on Cd-contaminated sediment and its interactions with microorganisms in relation to Cd fate remain unclear. The complexity of the external environment posed a challenge for Cd remediation. This study synthesized S-nZVI with different S and Fe precursors to investigate the effect of precursors and applied the optimal material to immobilize Cd in sediments. Characterization analysis revealed that the precursor affected the morphology, Fe0 crystallinity, and the degree of oxidation of the material. Incubation experiments demonstrated that the immobilization efficiency of Cd using S-nZVIFe3++S2- (S/Fe = 0.14) reached the peak value of 99.54%. 1% and 5% dosages of S-nZVI significantly reduced Cd concentration in the overlying water, DTPA-extractable Cd content, and exchangeable (EX) Cd speciation (P < 0.05). Cd leaching in sediment and total iron in the overlying water remained at low levels during 90 d of incubation. Notably, each treatment maintained a high Cd immobilization efficiency under different pH, water/sediment ratio, organic acid, and coexisting ion conditions. Sediment physicochemical properties, functional bacteria, and a range of adsorption, complexation and precipitation of CdS effects dominated Cd immobilization.

Affecting factors and mechanism of removing antibiotics and antibiotic resistance genes by nano zero-valent iron (nZVI) and modified nZVI: A critical review.

Antibiotics and antibiotic resistance genetic pollution have become a global environmental and health concern recently, with frequent detection in various environmental media. Therefore, finding ways to control antibiotics and antibiotic resistance genes (ARGs) is urgently needed. Nano zero-valent iron (nZVI) has shown a positive effect on antibiotics degradation and restraining ARGs, making it a promising solution for controlling antibiotics and ARGs. However, given the current increasingly fragmented research focus and results, a comprehensive review is still lacking. In this work, we first introduce the origin and transmission of antibiotics and ARGs in various environmental media, and then discuss the affecting factors during the degradation of antibiotics and the control of ARGs by nZVI and modified nZVI, including pH, nZVI dose, and oxidant concentration, etc. Then, the mechanisms of antibiotic and ARGs removal promoted by nZVI are also summarized. In general, the mechanism of antibiotic degradation by nZVI mainly includes adsorption and reduction, while promoting the biodegradation of antibiotics by affecting the microbial community. nZVI can also be combined with persulfates to degrade antibiotics through advanced oxidation processes. For the control of ARGs, nZVI not only changes the microbial community structure, but also affects the proliferation of ARGs through affecting the fate of mobile genetic elements (MGEs). Finally, some new ideas on the application of nZVI in the treatment of antibiotic resistance are proposed. This paper provides a reference for research and application in this field.

Activation of persulfate by biochar-supported sulfidized nanoscale zero-valent iron for degradation of ciprofloxacin in aqueous solution: process optimization and degradation pathway.

The pollution of antibiotics, specifically ciprofloxacin (CIP), has emerged as a significant issue in the aquatic environment. Advanced oxidation processes (AOPs) are capable of achieving stable and efficient removal of antibiotics from wastewater. In this work, biochar-supported sulfidized nanoscale zero-valent iron (S-nZVI/BC) was adopted to activate persulfate (PS) for the degradation of CIP. The impacts of different influencing factors such as S/Fe molar ratios, BC/S-nZVI mass ratios, PS concentration, S-nZVI/BC dosage, CIP concentration, initial pH, coexisting anions, and humic acid on CIP degradation efficiency were explored by batch experiments. The results demonstrated that the highest degradation ability of S-nZVI/BC was achieved when the S/Fe molar ratio was 0.07 and the BC/S-nZVI mass ratio was 1:1. Under the experimental conditions with 0.6 g/L S-nZVI/BC, 2 mmol/L PS, and 10 mg/L CIP, the degradation rate reached 97.45% after 90 min. The S-nZVI/BC + PS system showed significant degradation in the pH range from 3 to 9. The coexisting anions affected the CIP degradation efficiency in the following order: CO32- > NO3- > SO42- > Cl-. The radical quenching experiments and electron paramagnetic resonance (EPR) revealed that oxidative species, including SO4•-, HO•, •O2-, and 1O2, all contribute to the degradation of CIP, in which •O2- plays a particularly prominent role. Furthermore, the probable degradation pathway of CIP was explored according to the 12 degradation intermediates identified by LC-MS. This study provides a new idea for the activation method of PS and presents a new approach for the treatment of aqueous antibiotics with highly catalytic active nanomaterials.

Immobilization of cadmium in river sediments by different modified nanoscale zero-valent iron: performance, mechanisms, and Fe dissolution.

Modified nanoscale zero-valent iron (NZVI) exhibited great potential for the remediation of heavy metal contaminated river sediments, but its mechanisms and environmental risks are still unclear. This study systematically discussed the performance and the mechanisms of modified NZVI materials, i.e., sodium alginate-coated NZVI (SNZVI), rhamnolipid-coated NZVI (RNZVI), and graphene oxide-loaded NZVI (GNZVI), for the stabilization of Cd in sediment, with the exploration of their stability to Cd at various pH values and Fe dissolution rate. Compared with the control, the toxicity characteristic leaching procedure (TCLP) leachable Cd decreased by 52.66-96.28%, and the physiologically based extraction test (PBET) extractable Cd decreased by 44.68-70.21% after 56 days of incubation with the immobilization efficiency varying according to GNZVI > RNZVI > SNZVI > NZVI. Besides, the adsorption behavior of Cd on materials was fitted with the Freundlich model and classified as an endothermic, spontaneous, and chemical adsorption process. SEM-EDX, XRD, and FTIR results verified that the stabilization mechanisms of Cd were principally based on the adsorption, complexation of Cd2+ with secondary Fe minerals (including Fe2O3, γ-Fe2O3, and γ-FeOOH) and precipitation (Cd(OH)2). From the risk assessment results, it was observed that the materials were favorable for Cd stabilization at a pH range from 7 to 11, meanwhile, the leaching concentration of Fe in the overlying water was detected below the limit value. These findings pave the way to developing an effective strategy to remediate Cd contaminated river sediments.

Recent advances in sulfidized nanoscale zero-valent iron materials for environmental remediation and challenges.

Over the past decade, sulfidized nanoscale zero-valent iron (S-nZVI) has been developed as a promising tool for the remediation of contaminated soil, sediment, and water. Although most studies have focused on applying S-nZVI for clean-up purposes, there is still a lack of systematic summary and discussion from its synthesis, application, to toxicity assessment. This review firstly summarized and compared the properties of S-nZVI synthesized from one-step and two-step synthesis methods, and the modification protocols for obtaining better stability and reactivity. In the context of environmental remediation, this review outlined an update on the latest development of S-nZVI for removal of heavy metals, organic pollutants, antibiotic resistance genes (ARGs), and antibiotic resistant bacteria (ARB) and also discussed the underlying removal mechanisms. Environmental factors affecting the remediation performance of S-nZVI (e.g., humic acid, coexisting ions, S/Fe molar ratio, pH, and oxygen condition) were highlighted. Besides, the application potential of S-nZVI in advanced oxidation processes (AOP), especially in activating persulfate, was also evaluated. The toxicity impacts of S-nZVI on the environmental microorganism were described. Finally, the future challenges and remaining restrains to be resolved for better applicability of S-nZVI are also proposed. This review could provide guidance for the environmental remediation with S-nZVI-based technology from theoretical basis and practical perspectives.

Chromium(III) adsorption removal from acidic solutions by isomeric and tunnel-structural iron oxyhydroxides.

Iron oxyhydroxides for heavy metal treatment have attracted wide attention. In this work, iron oxyhydroxides of isomeric FeOOH (GpI) and tunnel-structural schwertmannite/akaganéite (GpII) were selected to study chromium (Cr(III)) adsorption removal from acidic aqueous solutions by batch experiments, under various reaction time, adsorbate/adsorbent level, pH and anions. Adsorption processes well fitted to pseudo-second-order kinetics (R2 = 0.992-0.999, except for 0.829 for Lep). Isotherm data could be fitted by Langmuir (R2 = 0.901-0.985), Freundlich (R2 = 0.884-0.985) and Temkin (R2 = 0.845-0.961) models at pH 3.7. Langmuir maximum adsorption capacities (mg/g) were 10.4-18.8 (FeOOH, except for 3.08 for Gth2) in GpI, and 20.60/43.40 (Sch-Chem/Sch-Bio) and 12.80/24.70 (Aka-Chem/Aka-Bio) in GpII. Adsorption capacities would gradually increase as Cr(III) concentrations increased within 0-40 mg/L, and could be markedly affected by the SO42- and H2PO4- anions. There were stable adsorption capacities at about pH 3.7, and then increased at pH 3.7-4.1. The Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) results showed that adsorption mechanisms were electrostatic interaction and surface complexation. In addition, three optimal bio-/chem-schwertmannite and lepidocrocite adsorbents had good reusable properties and treating abilities of Cr(III)-polluted waters at pH 4.0. These results could provide a theoretical basis for the application of iron oxyhydroxides in removing Cr(III) from acid wastewaters.

Multi-omics profiling visualizes dynamics of cardiac development and functions.

Cardiogenesis is a tightly regulated dynamic process through a continuum of differentiation and proliferation events. Key factors and pathways governing this process remain incompletely understood. Here, we investigate mice hearts from embryonic day 10.5 to postnatal week 8 and dissect developmental changes in phosphoproteome-, proteome-, metabolome-, and transcriptome-encompassing cardiogenesis and cardiac maturation. We identify mitogen-activated protein kinases as core kinases involved in transcriptional regulation by mediating the phosphorylation of chromatin remodeling proteins during early cardiogenesis. We construct the reciprocal regulatory network of transcription factors (TFs) and identify a series of TFs controlling early cardiogenesis involved in cycling-dependent proliferation. After birth, we identify cardiac resident macrophages with high arachidonic acid metabolism activities likely involved in the clearance of injured apoptotic cardiomyocytes. Together, our comprehensive multi-omics data offer a panoramic view of cardiac development and maturation that provides a resource for further in-depth functional exploration.

Synthesis of nanospindle-akaganéite and its photocatalytic degradation for methyl orange.

Iron oxyhydroxides as important catalysts and environmental mineral materials have drawn significant interest for their potential applications in the field of wastewater treatment. In this work, we investigated the influence of nonionic surfactant Brij30 or glucose (0.01 wt%) on the formation of iron precipitates in iron(III) chloride solutions for 3 days at 40, 60 and 80 °C. The results showed that the presence of glucose or Brij30 could promote the nanospindle-akaganéite formation and the akaganéite with a length of 300-500 nm obtained at 60 °C was the optimal catalyst for organic photocatalysis degradation. Further, we investigated the capacity of C60 akaganéite for degradation removal of methyl orange (MO) under the action of hydrogen peroxide (H2O2) addition and/or UV irradiation, and in the presence of different radical scavengers at pH 4.5. We also researched the effects of various levels of H2O2 and catalyst, and the reaction pH values. It was found that akaganéites could remove almost 100% of MO under 100 mg·L-1 of catalyst and H2O2 at pH 4.5. Akaganéite maintained 86% of MO removal capacity after four successive cycles. Our results can be used as a reference for the synthesis of environmentally functional material and the application in photocatalytic degradation of organic pollutant.

Adsorption removal of Cr(VI) by isomeric FeOOH.

The aim of this work is to study the performances of isomeric α-, ß-, and γ-FeOOH (goethite, akaganéite and lepidocrocite, including five samples named as Gth1 and Gth2, Aka1 and Aka2, and Lep, respectively) for removing hexavalent chromium (Cr(VI)) from aqueous solutions. The adsorption mechanisms were explored by kinetic and isothermal experiments. Adsorption efficiencies under the different pH values, anions, and the levels of adsorbate and adsorbent were also measured. Results showed that the Cr(VI) adsorption by isomeric FeOOH could be best described by pseudo-second-order kinetic model. The processes of Cr(VI) isothermal adsorption could be greatly fitted by the Langmuir and Freundlich equations with the high correlation coefficients of R2 (>0.92). Also, there were the optimum pH values of 3.0-8.0 for FeOOH to adsorb Cr(VI), and their adsorption capacities were tightly related with the active sites of adsorbents. Cr(VI) adsorptions by these adsorbents were easily influenced by H2PO4 -, and then SO4 2-, while there were little effects by Cl-, CO3 2- and NO3 -. These obtained results could provide a potentially theoretical evidence for isomeric FeOOH materials applied in the engineering treatment of the polluted chromate-rich waters.

Comparative study of dual energy CT iodine imaging and standardized concentrations before and after chemoradiotherapy for esophageal cancer.

BACKGROUND: To compare dual energy CT iodine imaging and standardized iodine concentration before and after chemoradiotherapy (CRT) for esophageal cancer and evaluate the efficacy of CRT for EC by examining DECT iodine maps and standard CT values. METHODS: The clinical data of 45 patients confirmed by pathology with newly diagnosed esophageal cancer who underwent concurrent CRT from February 2012 to January 2017 in our department of radiology were collected. All patients underwent dual-source dual-energy CT (DECT) before and after CRT. Normalized iodine concentration (NIC) and normalized CT (NCT) corresponding to the overall cancer lesion and its maximum cross-sectional area were observed and compared. Additionally, 30 healthy individuals were compared as control group. After treatment, the patients were divided into two groups according to RECIST1.1: treatment effective group and ineffective group. RESULTS: There were 33 patients (CR 9, PR 24) in the effective group and 12 patients (SD 12, PD 0) in the ineffective group. There was no significant difference in the NIC-A, NIC-V, NCT-A and NCT-A indexes between the effective group (B group) and the ineffective group (C group) before treatment (P > 0.05). After the treatment, the above-mentioned indexes in the effective group of patients were significantly lower than before treatment, and compared with the ineffective group, the NIC-A, NIC-V, NCT-A and NCT-V values of the effective group were significantly lower than those of ineffective group (P < 0.05). After treatment, the NIC-V and NCT-V in the ineffective group were lower than before treatment, and the difference was statistically significant (P < 0.05). However, their NIC-A and NCT-A were not statistically different from those before treatment (P > 0.05). CONCLUSION: Using DECT iodine map, the changes of NIC and NIC before and after CRT in patients with esophageal cancer can evaluate the effect of CRT, and does not increase the radiation dose, so it is suitable for clinical use.

Drastic Enhancement of H2O2 Electro-generation by Pulsed Current for Ibuprofen Degradation: Strategy Based on Decoupling Study on H2O2 Decomposition Pathways.

Efficient H2O2 electrogeneration from 2-electron oxygen reduction reaction (ORR) represents an important challenge for environmental remediation application. H2O2 production is determined by 2-electron ORR as well as H2O2 decomposition. In this work, a novel strategy based on the systematical investigation on H2O2 decomposition pathways was reported, presenting a drastically improved bulk H2O2 concentration. Results showed that bulk phase disproportion, cathodic reduction, and anodic oxidation all contributed to H2O2 depletion. To decrease the extent of H2O2 cathodic reduction, the pulsed current was applied and proved to be highly effective to lower the extent of H2O2 electroreduction. A systematic study of various pulsed current parameters showed that H2O2 concentration was significantly enhanced by 61.6% under pulsed current of "2s ON + 2s OFF" than constant current. A mechanism was proposed that under pulsed current, less H2O2 molecules were electroreduced when they diffused from the porous cathode to the bulk electrolyte. Further results demonstrated that a proper pulse frequency was necessary to achieve a higher H2O2 production. Finally, this strategy was applied to Electro-Fenton (EF) process with ibuprofen as model pollutant. 75.0% and 34.1% ibuprofen were removed under pulsed and constant current at 10 min, respectively. The result was in consistent with the higher H2O2 and ·OH production in EF under pulsed current. This work poses a potential approach to drastically enhance H2O2 production for improved EF performance on organic pollutants degradation without making any changes to the system except for power mode.

Comparative analysis of the response and gene regulation in cold resistant and susceptible tea plants.

Cold environment is the main constraint for tea plants (Camellia sinensis) distribution and tea farming. We identified two tea cultivars, called var. sinensis cv. Shuchazao (SCZ) with a high cold-tolerance and var. assamica cv. Yinghong9 (YH9) with low cold-tolerance. To better understand the response mechanism of tea plants under cold stress for improving breeding, we compared physiological and biochemical responses, and associated genes expression in response to 7-day and 14-day cold acclimation, followed by 7-day de-acclimation in these two tea cultivars. We found that the low EL50, low Fv/Fm, and high sucrose and raffinose accumulation are responsible for higher cold tolerance in SCZ comparing with YH9. We then measured the expression of 14 key homologous genes, known as involved in these responses in other plants, for each stages of treatment in both cultivars using RT-qPCR. Our results suggested that the increased expression of CsCBF1 and CsDHNs coupling with the accumulation of sucrose play key roles in conferring higher cold resistance in SCZ. Our findings have revealed key genes regulation responsible for cold resistance, which help to understand the cold-resistant mechanisms and guide breeding in tea plants.

Mass transfer characteristics, rheological behavior and fractal dimension of anammox granules: The roles of upflow velocity and temperature.

In this study, the mass transfer, rheological behavior and fractal dimension of anaerobic ammonium oxidation (anammox) granules in upflow anaerobic sludge blanket reactors at various temperatures (8.5-34.5°C) and upflow velocities (0.06, 0.18mh-1) were investigated. The results demonstrated that a lower temperature increased the external mass transfer coefficient and apparent viscosity and impaired the performance of anammox granules. The external mass transfer coefficient was decreased, but efficient nitrogen removal of up to 96% was achieved under high upflow velocity, which also decreased the apparent viscosity. Furthermore, a fractal dimension of up to 2.93 achieved at low temperature was higher than the previously reported values for mesophilic anammox granules. A higher upflow velocity was associated with the lower fractal dimension. Because of the disturbance in granule flaking, the effectiveness factor was less suitable than the external mass transfer coefficient for characterization of mass transfer resistance.

Individual and combined inhibition of phenol and thiocyanate on microbial activity of partial nitritation.

This study evaluated the individual and interactive effect of phenol and thiocyanate (SCN-) on partial nitritation (PN) activity using batch test and response surface methodology. The IC50 of phenol and SCN- on PN sludge were 5.6 and 351 mg L-1, respectively. The PN sludge was insensitive to phenol and SCN- at levels lower than 1.77 and 43.3 mg L-1, respectively. A regression model equation was developed and validated to predict the relative specific respiration rate (RSRR) of PN sludge exposed to different phenol and SCN- concentrations. In the range of independent variables, the most severe inhibition was observed with a valley value (17%) for RSRR, when the phenol and SCN- concentrations were 4.08 and 198 mg L-1, respectively. An isobole plot was used to judge the combined toxicity of phenol and SCN-, and the joint inhibitory effect was variable depending on the composition and concentration of the toxic components. Furthermore, the toxic compounds showed independent effects, which is the most common type of combined toxicity.

Development of a New Growth Standard for Breastfed Chinese Infants: What Is the Difference from the WHO Growth Standards?

The objectives of this longitudinal study were to examine the trajectory of breastfed infants' growth in China to update growth standards for early childhood, and to compare these updated Chinese growth standards with the growth standards recommended by the World Health Organization (WHO) in 2006.This longitudinal cohort study enrolled 1,840 healthy breastfed infants living in an "optimal" environment favorable to growth and followed up until one year of age from 2007 to 2010. The study subjects were recruited from 60 communities in twelve cities in China. A participating infant's birth weight was measured within the first hour of the infant's life, and birth length and head circumference within 24 hours after birth. Repeated weekly and monthly anthropometric measurements were also taken. Multilevel (ML) modelling via MLwiN2.25 was fitted to estimate the growth curves of weight-for-age (WFA), length-for-age (LFA), and head circumference-for-age (HFA) for the study sample as a whole and by child sex, controlling for mode of delivery, the gravidity and parity of the mother, infant's physical measurements at birth, infant's daily food intaking frequency per day, infant's medical conditions, the season when the infant's physical measurement was taken, parents' ages, heights, and attained education, and family structure and income per month. During the first four weeks after birth, breastfed infants showed an increase in weight, length, and head circumference of 1110g, 4.9 cm, and 3.2 cm, respectively, among boys, and 980 g, 4.4 cm, and 2.8 cm, respectively, among girls. Throughout infancy, the total growth for these three was 6930 g, 26.4 cm, and 12.5 cm, respectively, among boys, and 6480 g, 25.5 cm, and 11.7 cm, respectively, among girls. As expected, there was a significant sex difference in growth during the first year. In comparison with the WHO growth standards, breastfed children in our study were heavier in weight, longer in length, and bigger in head circumference, with the exception of a few age points during the first two to four months on the upper two percentile curves.Our data suggested the growth curves for breastfed infants in China were significantly different in comparison with those based on the WHO standards. The adoption of the WHO infant growth standards among Chinese infants, as well as the methods used in the development of such growth standards in China, need careful and coordinated consideration.

Mutual conversion and asymmetric transmission of linearly polarized light in bilayered chiral metamaterial.

We propose a kind of planar chiral optical metamaterial consisting of two layers of connected I-shape resonators arranged by a twist angle of 90°. Numerical simulation results demonstrate that our scheme can realize a mutual polarization conversion and dual-band asymmetric transmission for linearly polarized waves in the optical regime. For the forward propagation, the x-to-y and y-to-x polarization conversions in the proposed bilayered metamaterial result from the concentric and eccentric C-shaped dimers, respectively. The current distributions of bilayered metamaterials at the resonant frequencies are presented to interpret the dual-band asymmetric transmission. The polarization conversion efficiency and resonant frequencies can be modified via parametric study.

Isolation, identification and arsenic-resistance of Acidithiobacillus ferrooxidans HX3 producing schwertmannite.

Schwertmannite, a ubiquitous mineral present in iron oxyhydroxides formed in iron- and sulfate-rich acid media, favors incorporation of some toxic anions in its structure. We reported an iron-oxidizing bacterial strain HX3 from a municipal sludge that facilitates the formation of pure schwertmannite in cultures. Ferrous iron oxidation by the isolated strain HX3 was optimum at an initial pH of 2.0-3.3 and temperature of 28-35°C. Pure schwertmannite was found through bacterial oxidation of ferrous iron at an initial pH2.8 and temperature 28°C. Following 16S rDNA gene sequence analysis the bacterial strain HX3 was identified as Acidithiobacillus ferrooxidans. The arsenic-resistance A. ferrooxidans HX3 showed the potential of environmental application in arsenic removal from the As(III)- and iron-rich acid sulfate waters directly by As(III) adsorption or the formation of schwertmannite in the environment.

[Characterization and spectral analysis of the stable mineral phases alpha, beta-FeOOH included in iron oxyhydroxides].

In the present work, based on the stable phase of alpha-FeOOH and beta-FeOOH easily formed in ferric solutions of Fe (NO3)3 and FeCl3 at the appropriate pH values, respectively, the phase and crystallizability, morphologies and sizes for the particles of FeOOH minerals prepared under the conditions of heating at 40 and 70 degreeC, and magnetic stirring at 25 degreeC were identified and examined by X-ray diffraction (XRD), transmission/scanning electron microscopy (TEM/SEM) and laser scattering particle analyzer. Meanwhile the surface chemistry properties were also detected and analyzed by Fourier transform infrared spectrometer (FTIR). Investigation results showed that the prepared minerals Gth-T70 (alpha-FeOOH), Aka-T40 and Aka-T70 (beta-FeOOH) have good properties of nanocrystallity, homogeneous particles and higher specific surface areas, which induced that the above alpha, beta-FeOOH are potentially excellent adsorbent materials for removal of some contaminants in circumstances.