Effects of temperature and nitrogen sources on physiological performance of the coccolithophore Emiliania huxleyi.

Both temperature and nutrient levels are rising in worldwide ocean ecosystems, and they strongly influence biological responses of phytoplankton. However, few studies have addressed the interactive effects of temperature and nitrogen sources on physiological performance of the coccolithophore Emiliania huxleyi. In this study, we evaluated algal growth, photosynthesis and respiration, elemental composition, enzyme activity, and calcification under a matrix of two temperatures gradients (ambient temperature 20 °C and high temperature 24 °C) and two nitrogen sources (nitrate (NO3-) and ammonium (NH4+)). When the algae was cultured with NO3- medium, high temperature reduced algal photosynthesis and nitrate reductase activity, but it did not change other indicators significantly relative to ambient temperature. In addition, E. huxleyi preferred NO3- as the growth medium, whereas NH4+ had negative effects on physiological parameters. In the NH4+ medium, the growth rate, photosynthesis and photosynthetic rate, nitrate reductase activity, and particulate organic carbon and particulate organic nitrogen production rate of the algae decreased as temperature increased. Conversely, high temperature increased cellular particulate organic carbon, cellular particulate organic nitrogen, and particulate inorganic carbon levels. In summary, our findings indicate that the distribution and abundance of microalgae could be greatly affected under warming ocean temperature and different nutrient conditions.

Preparation of Surface-Active Hyperbranched-Polymer-Encapsulated Nanometal as a Highly Efficient Cracking Catalyst for In Situ Combustion of Heavy Oil.

In situ combustion of heavy oil is currently the most suitable thermal method that meets energy consumption and carbon dioxide emission requirements for heavy oil recovery. The combustion catalyst needs to perform multiple roles for application; it should be capable of catalyzing heavy oil combustion at high temperatures, as well as be able to migrate in the geological formation for injection. In this work, a hyperbranched polymer composite nanometal fluid was used as the injection vector for a heavy oil in situ combustion catalyst, which enabled the catalyst to rapidly migrate to the surface of the oil phase in porous media and promoted heavy oil cracking deposition at high temperatures. Platinum (Pt) nanoparticles encapsulated with cetyl-hyperbranched poly(amide-amine) (CPAMAM), with high interfacial activity, were synthesized by a facile phase-transfer method; the resulting material is called Pt@CPAMAM. Pt@CPAMAM has good dispersion, and as an aqueous solution, it can reduce the interfacial tension between heavy oil and water. As a catalyst, it can improve the conversion rate during the pyrolysis of heavy oil in a nitrogen atmosphere. The catalyst structure designed in this study is closer to that exhibited in practical geological formation applications, making it a potential method for preparing catalysts for use in heavy oil in situ combustion to resolve the problem of catalyst migration in the geological formation.

Effects of Palladium Precursors on the Activity of Palladium Nanocatalysts for the Oxidation of Volatile Organic Components.

To screen a suitable precursor, the effects of palladium salts on performance of Pd nanocatalysts for the oxidation of volatile organic components (VOCs) were investigated. A series of catalysts was prepared by impregnating Pd(NO3)2, PdCl2 and Pd(NH3)4Cl2 on alumina-coated cordierites. These catalysts were characterized by XRF, ICP-OES, XRD, N2 adsorption-desorption, TEM, EDS, Raman spectroscopy, pulse-CO chemisorption, H2-TPR, NH3-TPD, and XPS. Pulse-CO chemisorption and TEM showed that Pd species formed by Pd(NO3)2 have the highest metal dispersion (17.7%), while the other two were aggregating. For the same Pd loading, the higher the metal dispersion, the more the number of PdO species, so the number of PdO particles in the catalyst prepared from Pd (NO3) 2 is the largest. The catalytic oxidation activities of these catalysts were evaluated by ethane and propane. Based on a 99% conversion in the oxidation of ethane and propane at 598 K and 583 K, respectively, the catalyst prepared from Pd(NO3)2 was considered to be the best performing catalyst. The chloride species in precursors can promote the aggregation of Pd species and poison the catalysts. The results show that Pd(NO3)2 is more suitable as the precursor of VOC oxidation catalyst than PdCl2 and Pd(NH3)4Cl2.

Geometric parameters sensitivity evaluation based on projection trajectories for X-ray cone-beam computed laminography.

BACKGROUND: X-ray cone-beam computed laminography (CL) is widely used for large flat objects that computed tomography (CT) cannot investigate. The rotation angle of axis tilt makes geometric correction of CL system more complicated and has more uncertain factors. Therefore, it is necessary to evaluate sensitivity of the geometric parameters of CL system in advance. OBJECTIVE: This study aims to objectively and comprehensively evaluate sensitivity of CL geometric parameters based on the projection trajectory. METHODS: This study proposes the Minimum Deviation Unit (MDU) to evaluate sensitivity of CL geometric parameters. First, the projection trajectory formulas are derived according to the spatial relationship of CL system geometric parameters. Next, the MDU of the geometric parameters is obtained based on the projection trajectories and used as the evaluation index to measure the sensitivity of parameters. Then, the influence of the rotation angle of the axis tilt and magnification on the MDU of the parameters is analyzed. RESULTS: At low magnification, three susceptible parameters (η, u0, v0) with MDU less than 1 (° or mm) must be calibrated accurately to avoid geometric artifacts. The sensitivity of CL parameters increases as the magnification increases, and all parameters become highly sensitive when the magnification power is greater than 10. CONCLUSION: The results of this study have important guiding significance for the subsequent further parameter calibration.

Residue screening and analysis of enrofloxacin and its metabolites in real aquatic products based on ultrahigh-performance liquid chromatography coupled with high resolution mass spectrometry.

The abuse of enrofloxacin (ENR) in aquaculture and the lack of monitoring of other metabolites except ciprofloxacin (CIP) may lead to unknown harmful effects on human health. In this study, ENR metabolites were screened in real fish samples based on ultrahigh-performance liquid chromatography coupled with Q-Orbitrap mass spectrometry combined with Compound Discoverer software, and another metabolite deethylene-ENR besides CIP was detected and identified for the first time. Correspondingly, a method for the determination of ENR and CIP and the semi-quantitative analysis of deethylene-ENR in aquatic products was established. Method validation illustrated that excellent linearity and satisfactory recoveries of analytes were obtained. Limits of detection of ENR and CIP were both 0.1 µg kg-1, and their limits of quantification both 1 µg kg-1. CIP and deethylene-ENR were detected in 12 of 14 ENR-positive fish samples, so deethylene-ENR should be of concern as a possible risk candidate in aquatic products.

Determination of chlorpromazine and its metabolites in animal-derived foods using QuEChERS-based extraction, EMR-Lipid cleanup, and UHPLC-Q-Orbitrap MS analysis.

Chlorpromazine (CPZ) is abused in animal husbandry and can be extensively metabolized in humans and animals. However, the actual monitoring mainly focuses on the parent compound but lacks attention to its metabolites. A method was developed and validated firstly for identification and determination of CPZ and its four major metabolites in animal-derived foods using ultrahigh-performance liquid chromatography coupled with quadrupole-Orbitrap mass spectrometry in combination with QuEChERS preparation method. Satisfactory recoveries of analytes spiked in fish and pork samples ranged from 72 to 117 %, and limits of quantification were 2.0 and 1.0 µg kg-1 for fish and pork samples respectively. Moreover, through the hydrolysis experiments of CPZ, its hydrolysates, such as CPZ-sulfoxide, CPZ-N-oxide and CPZ-sulfoxide-N-oxide, were identified as potential risk compounds. The developed method has been successfully applied to the determination of CPZ and its metabolites in actual commercial samples, as well as to the screening of other CPZ-related risk compounds.

Oxidative stress and endoplasmic reticulum stress contributed to hepatotoxicity of decabromodiphenyl ethane (DBDPE) in L-02 cells.

Decabromodiphenyl ethane (DBDPE) is one of the most commonly used novel brominated flame retardants (NBFRs), and its mass production and widespread application have caused health threats to the human being. Existing studies have shown that DBDPE has hepatotoxicity. And we have found that DBDPE could change cytochrome P450 3A (CYP3A) expression levels in rat livers, whereas the mechanism is unclear. In this study, we exposed human normal hepatocyte (L-02) to DBDPE to further study the effect and mechanism of DBDPE on hepatocellular injury and liver metabolic enzyme CYP3A changes in vitro. The results showed that DBDPE caused L-02 cell viability decrease, lactate dehydrogenase (LDH) and transaminase release, ultrastructural damage, and apoptosis. Moreover, DBDPE exposure induced oxidative stress (i.e., increased ROS generation and MDA levels and decreased GSH content, SOD activity, and mitochondrial membrane potential) and endoplasmic reticulum (ER) stress in L-02 cells as evidenced by the elevated PERK and IRE-1α expression levels. These results confirmed that DBDPE is toxic to hepatocytes. Besides, the CYP3A expression level was decreased in DBDPE exposed L-02 cells. However, pretreatment of L-02 cells with antioxidant N-Acetyl-l-cysteine (NAC) and endoplasmic reticulum stress inhibitor 4-PBA inhibited DBDPE-induced oxidative stress, endoplasmic reticulum stress, CYP3A expression decrease, and apoptosis. Therefore, we demonstrated that DBDPE could exert toxic effects and decrease CYP3A expression on L-02 cells by inducing ER stress and oxidative stress.

Hepatotoxicity of decabromodiphenyl ethane (DBDPE) and decabromodiphenyl ether (BDE-209) in 28-day exposed Sprague-Dawley rats.

Decabromodiphenyl ether (BDE-209) and its substitute decabromodiphenyl ethane (DBDPE) are heavily used in various industrial products as flame retardant. They have been found to be persistent in the environment and have adverse health effects in humans. Although some former studies have reported toxic effects of BDE-209, the study of DBDPE's toxic effects is still in its infancy, and the effects of DBDPE on hepatotoxicity are also unclear. This study aimed to evaluate and compare the hepatotoxicity induced by BDE-209 and DBDPE using a rat model. Sprague-Dawley rats were administered DBDPE or BDE-209 (5, 50, 500 mg/kg bodyweight) intragastrically once a day for 28 days. Twenty-four hours after the end of treatment, the rats were sacrificed, and body liver weight, blood biochemical parameters, liver pathology, oxidative stress, inflammation, pregnane X receptor (PXR), constitutive androstane receptor (CAR), and changes in cytochrome P450 (CYP3A) enzymes were measured. Our results showed that both BDE-209 and DBDPE could cause liver morphological changes, induce oxidative stress, increase γ-glutamyl transferase and glucose levels in serum, and down-regulate PXR, CAR, and CYP3A expression. In addition, BDE-209 was found to increase liver weight and the ratio of liver/body weight, lead to elevated total bilirubin and indirect bilirubin levels in serum, and induce inflammation. The present study indicated that BDE-209 and DBDPE may interfere with normal metabolism in rats through oxidative stress and inflammation, which inhibit PXR and CAR to induce the expression of CYP3A enzymes, and finally produce hepatotoxic effects and cause liver damage in rats. Comparatively, our results show that the damage caused by BDE-209 was more serious than that caused by DBDPE.

A comparison of the thyroid disruption induced by decabrominated diphenyl ethers (BDE-209) and decabromodiphenyl ethane (DBDPE) in rats.

In recent years, decabromodiphenyl ethane (DBDPE), a new alternative flame retardant to the decabrominated diphenyl ethers (BDE-209), is widely used in a variety of products. Previous studies have indicated that DBDPE, like BDE-209, could disrupt thyroid function. However, compared with BDE-209, the degrees of thyrotoxicosis induced by DBDPE were not clear. In addition, the mechanism of thyrotoxicosis induced by DBDPE or BDE-209 was still under further investigation. In this study, male rats as a model were orally exposed to DBDPE or BDE-209 by 5, 50, 500 mg/kg bw/day for 28 days. Then, we assessed the thyrotoxicosis of DBDPE versus BDE-209 and explored the mechanisms of DBDPE and BDE-209-induced thyrotoxicosis. Results showed that decreased free triiodothyronine (FT3) and increased thyroid-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH) in serum were observed in both 500 mg/kg bw/day BDE-209 and DBDPE group. Decreased total thyroxine (TT4), total T3 (TT3), and free T4 (FT4) were only observed in BDE-209 group but not in DBDPE group. Histological examination and transmission electron microscope examination showed that high level exposure to BDE-209 and DBDPE both caused significant changes in histological structure and ultrastructure of the thyroid gland. Additionally, oxidative damages of thyroid gland (decreased SOD and GSH activities, and increased MDA content) were also observed in both BDE-209 and DBDPE groups. TG contents in the thyroid gland was reduced in BDE-209 group but not in DBDPE group. Both BDE-209 and DBDPE affected the expression of hypothalamic-pituitary-thyroid (HPT) axis related genes. These findings suggested that both BDE-209 and DBDPE exposure could disrupt thyroid function in the direction of hypothyroidism and the underlying mechanism was likely to be oxidative stress and perturbations of HPT axis. However, DBDPE was found to be less toxic than BDE-209.

Cardiovascular toxicity of decabrominated diphenyl ethers (BDE-209) and decabromodiphenyl ethane (DBDPE) in rats.

Recent reports indicated that decabrominated diphenyl ether (BDE-209) and decabromodiphenyl ethane (DBDPE) exist extensively in the environment. The toxicity of BDE-209 has been reported in quite a few studies, whereas the data of DBDPE are relatively rare. However, databases regarding cardiovascular toxicities of both BDE-209 and DBDPE are lacking. In this study, we investigated the vascular/cardiac trauma induced by DBDPE after oral exposure and compared the results with those of BDE-209 using rat model. Male rats were orally administered with corn oil containing DBDPE or BDE-209 (5, 50, 500 mg/kg/day) for 28 days, then oxidative stress, morphological and ultrastructural changes of the heart and abdominal aorta, levels of creatine kinase (CK) and lactate dehydrogenase (LDH), inflammatory cytokines, endothelin-1 (ET-1), and intercellular adhesion molecule-1 (ICAM-1) in the serum were monitored. Results showed that BDE-209 and DBDPE caused heart and abdominal aorta morphological and ultrastructural damage, serum CK and LDH elevation, and antioxidant enzyme activity changes. BDE-209 and DBDPE-induced inflammation was characterized by the upregulation of key inflammatory mediators, including interleukin-1beta (IL-1ß), IL-6, IL-10, and tumor necrosis factor alpha (TNFα). Additionally, BDE-209 and DBDPE led to endothelial dysfunction, as evidenced by the ET-1 and ICAM-1 elevation. Our findings demonstrated that BDE-209 and DBDPE could induce oxidative stress, inflammation, and eventually lead to endothelial dysfunction and cardiovascular injury. Compared to DBDPE, these toxic responses were stronger in the hearts and abdominal aorta of Sprague-Dawley rats exposed to BDE-209. Our findings indicated a potential deleterious effect of BDE-209 and DBDPE on the cardiovascular system.

Determination of polybrominated diphenyl ethers and novel brominated flame retardants in human serum by gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

The accurate detection of brominated flame retardants (BFRs) in humans is an area of high scientific interest and regulatory need due to their potential toxicity. The instrumental analysis of BFRs was commonly performed on gas chromatography-mass spectrometry (GC-MS) operating in electron ionization (EI) or negative chemical ionization (NCI) modes. However, soft ionization techniques, such as atmospheric pressure chemical ionization (APCI), may be more suitable for the analysis of BFRs because the BFRs show high fragmentation in EI and low selectivity in NCI. Additionally, accurate quantifications of BFRs in complex matrices is challenging due to their low concentrations and therefore, a highly sensitive technique is desperately needed. In this study, a new methodology based on gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (GC-APCI-MS/MS) analysis was developed for the determination of thirteen BFRs (eight usually monitored polybrominated diphenyl ethers (PBDEs) congeners and five additional novel BFRs) in human serum. The primary task was to evaluate the potential of the GC-APCI-MS/MS technique for the trace analysis of BFRs in human serum. The results of the spiked recovery test using fetal bovine serum showed that mean recoveries of the analytes ranged from 83.4% to 118% with reduced swing differential signaling (RSDs) of ≤21.1%. The methodological limits of detection (mLOD) of the analytes ranged from 0.04 to 30 pg/mL, and these values were at least one order of magnitude lower than those estimated by the authors in a previous study using GC-NCI-MS or GC-EI-MS/MS, indicating that GC-APCI-MS/MS is more sensitive. Specially, compared to GC-NCI-MS and GC-EI-MS/MS, when GC-APCI-MS/MS was used for the detection of highly brominated BFRs, such as BDE-209 and decabromodiphenyl ethane (DBDPE), a notable improvement in sensitivity and reliability was obtained using a deactivated capillary column connected to the analytical column as the transfer line and maintaining a high temperature to improve the chromatographic behaviors. The developed methodology was successfully used for the analysis of BFRs in human serum collected from residents living in a BFR production area and Beijing.

Generative and discriminative learning by CL-Net.

This correspondence presents a two-stage classification learning algorithm. The first stage approximates the class-conditional distribution of a discrete space using a separate mixture model, and the second stage investigates the class posterior probabilities by training a network. The first stage explores the generative information that is inherent in each class by using the Chow-Liu (CL) method, which approximates high-dimensional probability with a tree structure, namely, a dependence tree, whereas the second stage concentrates on discriminative learning to distinguish between classes. The resulting learning algorithm integrates the advantages of both generative learning and discriminative learning. Because it uses CL dependence-tree estimation, we call our algorithm CL-Net. Empirical tests indicate that the proposed learning algorithm makes significant improvements when compared with the related classifiers that are constructed by either generative learning or discriminative learning.

[Spatial and temporal differentiation of mountainous soil organic matter delta 13C in Dinghushan Biosphere Reserve].

Based on the determinations of soil organic matter (SOM) content, SOM delta 14C, and SOM delta13C of the samples collected by thin-layered sampling method, this paper studied the spatial and temporal differentiation of SOM delta13 C in the soil profiles at different altitudes in Dinghushan Biosphere Reserve. The results showed that the vertical differentiation of SOM delta13C at different altitudes was controlled by the development of soil profile, and closely correlated with the composition of SOM and its turnover processes. The fractionation of carbon isotope was happened during both the transformation of vegetation debris into topsoil organic matter (OM) and its regeneration after the topsoil buried, which resulted in a significant increase of SOM delta13C. Relative to plant debris delta13C, the delta13 C increment of topsoil OM was more dependent on its turnover rate. Both the delta13C of plant debris and topsoil OM increased with altitude, indicating the regular variation of vegetations with altitude, which was consensus to the vertical distribution of vegetations in Dinghushan Biosphere Reserve. Soil profiles at different altitudes had similar characteristics in vertical differentiation of SOM delta13C, vertical distribution of SOM content, and increasing apparent age of SOM 14C with soil depth, which were resulted from the successive turnover of SOM during the development of soil profile. The maximum depth of SOM delta13C in soil profile was different in origin and magnitude with the penetration depth of 14C produced by nuclear explosion in the atmosphere, indicating the controlling effects of topography and vegetation on the distribution of SOM carbon isotope with soil depth.

[Quantitative simulation on the vertical distribution of soil organic matters in mountainous soil profiles in the subtropical area, south China].

Quantitative descriptions of soil organic matter (SOM) dynamics, i.e., their distribution, turnover and movement, are essential for the running of the simulation of terrestrial ecosystem organic matter models. In this study, based on utilizing SOM diffusion-translation-decomposition model, two soil profiles were selected in different vegetation zones at Dinghushan Mountain for quantitative studies on SOM dynamics and their controlling factors. SOM were divided into three kinds of compartments: rapid compartment with turnover rate of 0.1-1.yr-1, slow compartment with turnover rate of 0.002-0.02.yr-1, and stable compartment with turnover rate of 0.0001-0.001.yr-1. The numerical results suggested that SOM distribution in soil profile in subtropical mountainous areas of south China obeyed the law of diffusion motion, translation motion and decomposition. The turnover rate of SOM rapid compartment was 0.483.yr-1 in the forest vegetation zone, and was 0.694.yr-1 in the shrub vegetation zone. The turnover rates of SOM slow compartment in the two kinds of vegetation zones were both 0.02.yr-1, and the turnover rates of SOM stable compartment in the two kinds of vegetation zones were both 0.001.yr-1. SOM diffusion rate and translation rate for the forest vegetation zone was 4 cm2.yr-1 and 0.2 mm.yr-1, respectively, and the two rates of the shrub vegetation zone were 1 cm2.yr-1 and 0.5 mm.yr-1, respectively. The obvious discrepancy between numerical values and measuring values for SOM content occurred in the 0-10 cm sections of the profiles, which might be due to the fact that the upper sections were at the interface between lithosphere and atmosphere, and were influenced directly by changes of climatic and environmental factors. The two kinds of values for SOM content were identical below the upper section of the profiles, and it indicated stable pedogenesis environments. Diffusion motion had obvious influences on SOM vertical distribution, and translation motion had clear impacts on SOM distribution only in the upper 0-10 cm section. Comparison analysis suggested that SOM dynamics were controlled mainly by soil profile qualities such as SOM content, clay content, soil fabric, void types and their developments, soil fauna and microorganism activities, etc. With the increasing of primary production of aboveground vegetation, the turnover rate of SOM rapid compartment decreased and SOM content increased, which provided scientific basis for increasing soil carbon sink through anthropogenic effects.