Search

In order to remove nitric oxide (NO) from flue gas, from small coal-fired boilers, it is necessary to exploit the cost-effective wet denitration technology. The absorption of NO with sodium chlorate solution was studied. The effects of experimental conditions, such as temperature, NaClO3 concentration, type of acid, mole ratio of NaClO3 to hydrogen ions, on NO removal rate were investigated, and the optimal conditions were established. As the effect of temperature on denitration was related to the type of acid used, the temperature required for sulfuric acid was high, and the temperature required for nitric acid was low. The optimal mole ratio between NaClO3 and the two types of acids was the same. The reaction products were analyzed by ion chromatography. The reacted solution could be recycled after the removal of sodium chloride. The reaction mechanism and the total chemical reaction equation of NaClO3 denitration were deduced. The thermodynamic derivations showed that this oxidation reaction could proceed spontaneously and the reaction was very thorough. NaClO3 exhibited high NO removal efficiency and its denitration cost was much lower than sodium chlorite. [ABSTRACT FROM AUTHOR]

With the development of pure organic room-temperature phosphorescence (ORTP), study in excitation-dependent fluorescence-phosphorescence (ExDFPh) dual emission materials is burgeoning. Herein, using formylphenylboronic acid (FPBA) as a prototype, the effect of substitution position on the ExDFPh properties was investigated. Among the three isomers, 4-FPBA exhibits outstanding ExDFPh behavior. Its luminescence color could turn from yellow to white to blue through decreasing the excitation energy. Importantly, dual phosphorescence-emitting species were observed and verified, which updates the understanding of the RTP mechanism. The difference in the ExDFPh behavior is possibly attributed to the RTP performance which is drastically affected by substitution position. Crystal analyses reveal that the intermolecular hydrogen-bond interaction changes from two to one to zero-dimension with varying substitution patterns from para- to meta- to ortho-position, which would affect the RTP emission. This is further proved by the comparison with the corresponding boronic ester, which contains no typical hydrogen bonds in the crystal structure. Theoretical calculation indicates that the intermolecular interaction would also play an important role in the intersystem crossing of the higher-lying singlet excited state. Based on the multi-color emission, potential application in anticounterfeiting is exhibited. [ABSTRACT FROM AUTHOR]

The extraction behavior of Pr(III) has been investigated using four kinds of unsymmetrical diglycolamide (DGA) extractants having different alkyl chain lengths, namely N,N'-dimethyl-N,N'-didodecyldiglycolamide (DMDDdDGA), N,N'-diethyl-N,N'-didodecyldiglycolamide (DEDDdDGA), N,N'-dipropyl-N,N'-didodecyldiglycolamide (DPDDdDGA) and N,N'-dibutyl- N,N'-didodecyldiglycolamide (DBDDdDGA). The effect of the alkyl chain of amidic N atoms in DGAs on the extraction ability of Pr(III) is discussed. The extraction of hydrochloric acid and Pr(III) from hydrochloric acid medium by DGAs in sulfonated kerosene, toluene and octanol was studied. The effect of extractant concentration and diluents on the distribution ratio (D) of Pr(III) was investigated to understand the extraction mechanism. Pr(III) and Fe(III) can be separated very well by DMDDdDGA and DBDDdDGA diluted by toluene in hydrochloric acid solution. IR spectra of extracted species of DGA.HCl and DGA.Pr(III) were recorded to study the structure of the extracted species. [ABSTRACT FROM AUTHOR]

With the aid of seismic geomorphology method, depositional systems such as fluvial-delta and turbidity current of the Cretaceous Quantou-Nenjiang Formations in Sangliao Basin were studied in detail as well as the morphology, dimension, depositional structures and boundaries of these sedimentary bodies. A geological model of a point bar in a fluvial system and the method to identify paleocurrent direction were proposed. The delta of Yaojia Formation with a gentle slope less than 1.4‰ in trangressive system tract (TST) was controlled by lake waves. Subaqueous distributary channels were widely developed in large-scale delta front with a width more than 16 km. Fluvial-dominated deltas with leaf and bird's foot shapes were widespread in highstand system tract (HST) of Qinshankou and Nengjiang Formation with moderately high slope gradients of 4‰ and 6.7‰.The width of the leaf-like and bird's foot delta front ranges from 1 km to 4 km and 3 km–5 km respectively. The mouth bar were well preserved due to the poorly developed widely distributed subaqueous distributary channels and the delta plains having widths of 9 km–15 km, 16 km-25 km respectively. Many turbidity current systems were recognized in the TST of the first member of Nengjiang Formation and the distribution area is about 10,000 km 2 . Fourteen sublacustrine fans with different dimension were formed by ten fluvial-delta systems extending 30 km–70 km toward the lake from the west and south. With the application of seismic geomorphology, the analysis of fluvial system, delta system and turbidity current system could switch from approximation to quantitative analysis. Sedimentary model proposed for point bars and the quantitative analysis of delta system could provide new technical support for exploration and drilling plan. The research on turbidity current systems will also be beneficial for new exploration targets. [ABSTRACT FROM AUTHOR]

Co-contamination of antibiotics and heavy metals prevails in the environment, and may play an important role in disseminating bacterial antibiotic resistance, but the selective effects of heavy metals on bacterial antibiotic resistance is largely unclear. To investigate this, the effects of heavy metals on antibiotic resistance were studied in a genome-sequenced bacterium, LSJC7. The results showed that the presence of arsenate, copper, and zinc were implicated in fortifying the resistance of LSJC7 towards tetracycline. The concentrations of heavy metals required to induce antibiotic resistance, i.e., the minimum heavy metal concentrations (MHCs), were far below (up to 64-fold) the minimum inhibition concentrations (MIC) of LSJC7. This finding indicates that the relatively low heavy metal levels in polluted environments and in treated humans and animals might be sufficient to induce bacterial antibiotic resistance. In addition, heavy metal induced antibiotic resistance was also observed for a combination of arsenate and chloramphenicol in LSJC7, and copper/zinc and tetracycline in antibiotic susceptible strain Escherichia coli DH5α. Overall, this study implies that heavy metal induced antibiotic resistance might be ubiquitous among various microbial species and suggests that it might play a role in the emergence and spread of antibiotic resistance in metal and antibiotic co-contaminated environments. [ABSTRACT FROM AUTHOR]

The behavior of Sm(III) and Nd(III) during extraction with N,N,N',N'-tetrabutyl-3-oxa-diglycolamide (TBDGA) in 70% kerosene--30 % n-octanol from hydrochloride acid was studied. The effects of temperature and the concentrations of hydrochloric acid and extractant on the distribution of the rare earth elements were investigated. The extraction mechanism was established and the stoichiometry of the main extracted species was confirm to be SmCl3•2TBDGA and NdCl3•2TBDGA for Sm(III) and Nd(III), respectively. The extraction distribution ratio decreased with increasing temperature, which demonstrates that the extraction reaction is exothermic. The IR spectra of the loaded organic phase and free extractant were recorded and are discussed. [ABSTRACT FROM AUTHOR]

Paddy rice has been likened to nictiana sp in its ability to scavenge cadmium (Cd) from soil, whereas arsenic (As) accumulation is commonly an order of magnitude higher than in other cereal crops. In areas such as those found in parts of Hunan province in south central China, base-metal mining activities and rice farming coexist. Therefore there is a considerable likelihood that lead (Pb), in addition to Cd and As, will accumulate in rice grown in parts of this region above levels suitable for human consumption. To test this hypothesis, a widespread provincial survey of rice from mine spoilt paddies (n = 100), in addition to a follow-up market grain survey (n = 122) conducted in mine impacted areas was undertaken to determine the safety of local rice supply networks. Furthermore, a specific Cd, As, and Pb biogeochemical survey of paddy soil and rice was conducted within southern China, targeting sites impacted by mining of varying intensities to calibrate rice metal(loid) transfer models and transfer factors that can be used to predict tissue loading. Results revealed a number of highly significant correlations between shoot husk, bran, and endosperm rice tissue fractions and that rice from mining areas was enriched in Cd, As, and Pb. Sixty-five, 50, and 34% of all the mine-impacted field rice was predicted to fail national food standards for Cd, As, and Pb, respectively. Although, not as elevated as the grains from the mine-impacted field survey, it was demonstrated that metal(loid) tainted rice was entering food supply chains intended for direct human consumption. [ABSTRACT FROM AUTHOR]

Novel sandwich structure SiO2@AuAg@CeO2 nanospheres (SACs), as low-temperature CO oxidation catalysts, were designed and prepared in this work. The SACs include SiO2 nanosphere support, embedded bimetallic AuAg nanoparticles, and CeO2 shell. The transmission electron microscope (TEM), elemental mapping images, and ultraviolet-visible (UV-vis) spectroscopy indicated the successful fabrication of the SACs sandwich structure. The catalytic performance of SACs varies with the AuAg composition and achieves the best catalytic activity when Au/Ag atomic ratio is 2:1. The strong synergistic effect of AuAg alloy remarkably promotes the CO oxidation through facilitating the adsorption of CO and O2 on the AuAg nanoparticles. The CeO2 non-compact shell not only provides effective protection for AuAg nanoparticles from aggregation but also gives CO full access to the catalysts. With unique sandwich structure and specific chemical composition, the SiO2@Au2Ag1@CeO2 nanospheres with CeO2 shell thickness of 5 nm present excellent low-temperature catalytic activity and high-temperature thermal stability. [ABSTRACT FROM AUTHOR]

Iron ore tailings (FeT) and manganese ore tailings (MnT), which are abundant and inexpensive materials that contain many trace elements, were employed for the remediation of As-contaminated soil to mitigate As accumulation in rice under greenhouse conditions. Prior to the experiments, the toxicities of both amendments were assessed with the toxicity characteristic leaching procedure (TCLP) and horizontal vibration method (HVM). Based on the assessment results, both amendments were pretreated until no As was present in the leaching solution. After application of both amendments to the soil, the soil pH increased significantly (p < 0.05). The ranges of As concentrations in husk and brown rice samples were 0.13-1.54 mg kg-1 and 0.06-0.42 mg kg-1, respectively. The lowest concentrations of As (0.06±0.02 mg kg-1) in rice grains were observed with MnT treatment, which was related to the structure and composition of MnT. There was a significant negative relationship (p < 0.05) between Mn and As in rice plants, while there was a significant positive relationship (p < 0.05) between Fe and As in rice plants as well as the ratio of Fe/Mn and As in rice plants. In conclusion, MnT could potentially be useful as an amendment to remediate As-contaminated soil and control As uptake by rice plants. [ABSTRACT FROM AUTHOR]

The vapor-liquid equilibrium (VLE) data of the ethanol + sec-butyl acetate, 1-propanol + sec-butyl acetate, and 2-propanol + sec-butyl acetate mixtures were determined at 101.3 kPa. The first principle quantum chemistry calculation method, which focuses on the hydrogen bond and interaction energies, is used to give insight into interactions at the molecular level. The experimental VLE data passed the thermodynamic consistency test. The data were regressed using Wilson, nonrandom two liquids, and universal quasi-chemical equations. The 1-propanol + sec-butyl acetate mixture forms a minimum temperature azeotropic mixture. The azeotropic temperature is 370.01 K, and the composition of 1-propanol is 89.2 mol % when calculated with the Wilson model. [ABSTRACT FROM AUTHOR]

Although the effect of CeO2 morphology on catalytic properties has been studied, research interests mainly focus on the oxidation reactions while the effect of CeO2 morphology on other reactions, such as dehydrogenation reaction, has rarely been reported. In this study, the dehydrogenation of ammonia borane (AB) was chosen as a model reaction to study the effect of CeO2 morphology (“c”, “r” and “o” denote cube, rod, and octahedron, respectively) on the catalytic properties of Ru/CeO2. Our study shows that the activity follows the order of Ru/c-CeO2 > Ru/r-CeO2 > Ru/o-CeO2, which is different from the order observed in other catalytic oxidation reactions. X-ray photoelectron spectroscopy (XPS), Raman and H2-Temperature program reduction (H2-TPR) measurements reveal that there is a weak interaction between Ru and c-CeO2, and metallic Ru is the dominant species in Ru/c-CeO2, which are possibly responsible for the highest catalytic activities among three Ru/CeO2 catalysts. [ABSTRACT FROM AUTHOR]

The isobaric vapor-liquid equilibrium (VLE) data of methyl ethyl ketone (MEK) + sec-butyl acetate (SBAC), 2-methoxyethanol + SBAC, and 1, 2-dimethoxyethane (DME) + SBAC were determined at 101.3 kPa by using an Ellis vapor-liquid equilibrium still. The experimental data passed the thermodynamic consistency test by Herington method and Wisniak test. The VLE values were correlated by the nonrandom two-liquid (NRTL), universal quasichemical activity coefficience (UNIQUAC), and Wilson activity-coefficient models. The results indicated that the three models had good agreement with the experimental data. The 2-methoxyethanol + SBAC system forms a minimum temperature binary azeotrope at 101.3 kPa. The azeotropic temperature is 383.86 K, and the composition of SBAC is 85.1 mol %. [ABSTRACT FROM AUTHOR]

Arsenic (As) speciation and distribution are two important factors in assessing human health risk from As-contaminated soil. In this study, we used the combination of physiologically based extraction test (PBET) and Simulator of Human Intestinal Microbial Ecosystem (SHIME) to determine soil As metabolism by human gut microbiota. The results showed that the percentage of soil arsenate [As(V)] transformation reached 22.1-38.2%, while that of arsenite [As(III)] attained 66.5-92.0%; 30.1-56.4% of As(V) transformed was attached to the soil solid phase. In comparison to sequential extraction results, almost all amorphous Fe/Al-oxide-bound As was liberated in the colon phase. An X-ray absorption near-edge structure (XANES) showed that the As(III) percentage in the soil solid phase reached 16.6-26.9% and reached 73.4% (soil 1) in the colon phase. Additionally, plenty of As(III) and different extents of methylation were also observed in colon extraction solution. As bioaccessibility in the colon phase was 1.8-2.8 times that in the small intestinal phase. Our results indicated that human gut microbiota increased As bioaccessibility, and large amounts of As(III) were adsorbed onto the soil solid phase as a result of microbial reduction. Determining As speciation and distribution in extraction solution and soil solid phases will allow for an accurate assessment of the risk to human health upon soil As exposure. [ABSTRACT FROM AUTHOR]

Reactions of lithio-o-carborane with isocyanates under various conditions were studied, and the structural features of the resulting carboranylamides are described. The reactions of o-carborane (o-C2B10H12), n-BuLi (two equiv.) and two equiv. of (substituted) phenylisocyanate, pentylisocyanate and p-ethylphenylthioisocyanate in diethyl ether, respectively, led, after workup, to the corresponding mono-substituted carboranylamide 2a-g and carboranylthioamide 5 in low to moderate yields, and only with RNCO (R = Ph, m-MeOC6H4, pentyl) could disubstituted products 3a-c be isolated. The reaction with phenylisocyanate afforded the mono-amide and di-amide products in a ratio of approximately 1 : 2, whereas in the other two reactions the ratios are approximately 4 : 1 and 3 : 2, respectively. In tetrahydrofuran all the reactions attempted with RNCO (R = Ph, p-IC6H4, m-NCC6H4 and pentyl) gave more monoamide products than those in diethyl ether. With phenylisocyanate no diamide product was isolated and with pentylisocyanate the ratio between monoamide and diamide is approximately 3.5 : 1. The new carboranylamides were characterized by means of elemental analyses, IR and NMR spectroscopy and mass spectrometry, as well as single-crystal X-ray diffraction analyses of 2a-f, 3a and 5. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the structure, hydrogen storage performance, electrochemical discharge and cyclic characteristics of La0.7Mg0.3Ni3.2Co0.35−XCuX alloys were investigated using X-ray diffraction (XRD), pressure composition isotherm (PCT) and electrochemical tests. XRD tests showed that all of the alloys were composed of La2Ni7 and LaNi phases. The ratio of LaNi phase in these alloys increased with increasing substitution of Cu for Co. PCT tests showed that increasing substitution of Cu for Co resulted in the decrease of hydrogen storage capacity and the increase of plateau pressure. Electrochemical discharge tests showed that the discharge capacity increased first and then decreased with increasing substitution of Cu for Co. [ABSTRACT FROM AUTHOR]

An extensive data set of total arsenic analysis for 901 polished (white) grain samples, originating from 10 countries from 4 continents, was compiled. The samples represented the baseline (i.e., not specifically collected from arsenic contaminated areas), and all were for market sale in major conurbations. Median total arsenic contents of rice varied 7-fold, with Egypt (0.04 mg/kg) and India (0.07 mg/kg) having the lowest arsenic content while the U.S. (0.25 mg/kg) and France (0.28 mg/kg) had the highest content Global distribution of total arsenic in rice was modeled by weighting each country's arsenic distribution by that country's contribution to global production. A subset of 63 samples from Bangladesh, China, India, Italy, and the U.S. was analyzed for arsenic species. The relationship between inorganic arsenic content versus total arsenic content significantly differed among countries, with Bangladesh and India having the steepest slope in linear regression, and the U.S. having the shallowest slope. Using country-specific rice consumption data, daily intake of inorganic arsenic was estimated and the associated internal cancer risk was calculated using the U.S. [ABSTRACT FROM AUTHOR]