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International audience; Ambient measurements of PM2.5-bounded polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and oxy-PAHs (OPAHs) were conducted during the summer in Jinan, China, an urban site, and at Tuoji island and Mt. Tai, two background locations. 3.5 h and 11.5 h sampling intervals in daytime and nighttime were utilized to research the diurnal variations of PAHs, NPAHs, and OPAHs. The concentrations of PAHs, NPAHs, and OPAHs were highest at the urban site and lowest at the marine site. The diurnal patterns of PAHs and NPAHs at the urban and marine sites were dissimilar to those observed at the mountain site partly due to the influence of the boundary layer. Vehicle emissions at the urban site made a large contribution to high molecular weight PAHs. 1N-PYR and 7N-BaA during morning and night sampling periods in JN were relatively high. Fossil fuel combustion and biomass burning were the main sources for all three sites during the sampling periods. The air masses at the marine and mountain sites were strongly impacted by photo-degradation, and the air masses at the marine site were the most aged. Secondary formation of NPAHs was mainly initiated by OH radicals at all the three sites and was strongest at the marine site. Secondary formation was most efficient during the daytime at the urban and mountain sites and during morning periods at the marine site. The average excess cancer risk from inhalation (ECR) for 70 years' life span at the urban site was much higher than those calculated for the background sites.

In the image classification task, traditional model can only recognize annotated image samples, but class labels can't involve all the object categories. In order to reduce the dependence on the labels and recognize unannotated object samples, this paper proposes zero-shot image classification based on attribute. The binary attribute is used as the intermediate knowledge to migrate learned knowledge from training samples domain to test samples domain. Using the classification model of the multi-loss function based on ResNet-50 to predict the object attributes. Then, using an attribute matrix to represent the correspondence between the object class and the attribute. Finally, the result of attribute prediction is combined with the prior knowledge of the attribute matrix to get the category. Compared with the traditional image classification method, the attribute learning model is applied to the zero-shot image classification. The experimental data show that the method improves the recognition accuracy of the image and improves the flexibility of the image classification task, which lays the foundation for the multi-source domain adaptation induction problem.

In this study, a stable cadmium(II)-based metal-organic framework (MOF) material was designed and used as a sorbent for the dispersive solid-phase extraction (dSPE) of polybrominated diphenyl ethers (PBDEs) in environmental water samples. Gas chromatography coupled with triple quadrupole mass spectrometer (GC-MS/MS), working in the negative chemical ionization mode, was used to quantify the target analytes. Characterization of the material was performed by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), elementary analyses (EA) and thermogravimetric analyses (TGA). The synthesized rod shape MOF is on the micro level in size and has excellent chemical and solvent stability. The extraction conditions, including the extraction time, temperature and ionic strength, were examined systematically using response surface methodology (RSM). Under optimized conditions, the method that was developed showed an excellent extraction performance. Good linearity (R(2)>0.99) within the concentration range of 0.25-250ngL(-1) was obtained. Low limits of detection (0.08-0.15ngL(-1), signal-to-noise ratio=3:1) and good precision (relative standard deviation

In this paper, we report the use of a porous ytterbium-based metal-organic framework (Yb-MOF) coating material with good thermal stability for the headspace solid-phase microextraction (HS-SPME) of polycyclic aromatic hydrocarbons (PAHs) from environmental samples. The Yb-MOF thin films, grown in situ on stainless steel wire in solution, exhibited high selectivity and sensitivity toward PAHs. Under the optimal conditions, the novel fibers achieved large enrichment factors (130-2288), low limits of detection (0.07-1.67ngL(-1)), and wide range of linearity (10-1000ngL(-1)) for 16 PAHs in the tested samples. The novel fiber was successfully used in the analysis of PAHs in real environmental samples. These results demonstrated that Yb-MOF is a promising coating material for the SPME of PAHs at trace levels from environmental samples.

RATIONALE The electron capture dissociation (ECD) of proteins/peptides is affected by the nature and sequence of amino acid residues. Electron capture/transfer with no dissociation is an intriguing phenomenon that has occasionally been observed. We have previously identified that diarginated peptides enriched with glutamic acid residues were found to show suppression of backbone fragmentation. In this paper, we report the effect of geometrical parameters of a peptide, including chain length, conformation and amide hydrogen, on the suppression of ECD fragmentation using synthetic model peptides. METHODS Glycine containing model polypeptides were used to probe the mechanism. Molecular-mechanics was used to obtain the conformation of the precursor ions. The ECD experiments were performed on a Bruker APEX III 4.7 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. RESULTS Significant decreases in the intensities of the fragment ions were observed for the 23-mer polypeptide with only one E residue. This implied that the E:R ratio was no longer the sole determining factor for the occurrence of suppression effects. Results of conformational searches showed that there was a hydrogen-bonding 'ladder' formed in the 23-mer polypeptide, which was not found in the 15-mer peptide. Substituting the normal amino acid residues by the corresponding N-methylated amino acid residues in the model peptide, the suppression effect disappeared. CONCLUSIONS Our results indicate that survival of the intact reduced peptide ion after electron capture depends also on the length of the peptide. The amide hydrogen was critical in forming the resonance structure that suppressed the ECD fragmentation.

In this paper, a new configuration of the ion funnel interface (i.e., V-shape ion funnel (V-IF)) for high ion transmission efficiency and robustness enhancement was developed and implemented on FTICR-MS. The performance of the V-IF was compared with that of a home-built orthogonal ion funnel. An order of magnitude of improvement in sensitivity was achieved for various peptides and proteins. The performance of the instrument was maintained for a long period by neutral molecule removal. Other ion transmission patterns, such as gentle ion transmission, adduct ion removal, and radio frequency (RF)-driven collision induced dissociation (CID), was also realized in V-IF by varying the RF potentials. V-IF is believed to be a novel ion guide that has promising applications in mass spectrometry.

The gas-phase dissociation pathways of proteins/peptides are usually affected by the nature of the charge carrier and the sequence of amino acid residues. The effects of peptide structural parameters, including peptide composition, chain length and amide hydrogen, on the gas-phase dissociation of Cu(II)–model peptide complexes were explored in this study. Polyglycine peptides with flexible frames were used as probes to reduce the complexity of the system and illustrate the mechanism. Results revealed that the types of fragment ions generated in the electron capture dissociation (ECD) of Cu(II)-adducted peptides changed according to the basic amino acid residue composition. Charged or neutral tryptophan side-chain losses were observed in the collision-induced dissociation (CID) of Cu(II)–peptide complexes. Internal electron transfer between tryptophan and metal ion within the complex occurred during the CID reaction, leaving the charge-reduced Cu+ as a closed d-shell stable electron configuration. The choice of the reaction channel was then determined by the gas-phase basicity of the peptide. Amide hydrogen was critical in the formation of metalated b-/ y-ions in the ECD process as determined through mutation of the backbone amide group. Increasing the chain length suppressed the ECD of Cu-metalated peptide species. Our results indicate that the structural parameters of peptides play important roles in the gas-phase dissociation processes of Cu–peptide complexes.

It has been previously reported that the glycosylation site and protein-sequence information could be obtained for ribonuclease B by top-down electron-capture dissociation (ECD) and collision-induced dissociation (CID) mass spectrometry (MS). However, the sequence coverage of ribonuclease B was limited in a single activation, and the structural information on the glycan moiety was not probed successfully in previous experiments. Here, we demonstrate that ECD and CID techniques can be used together as an effective top-down method for the structural characterization of intact glycoprotein. Even without an elaborate pre- or post-ECD activation, a high sequence coverage (>90%) of ribonuclease B could be achieved with substantial amounts of structural information for the glycan moiety. By comparing our work with previous results, it is postulated that the disulfide bond reduction strategy might play a significant role in determining the efficiency of top-down MS.

A method combining accelerated solvent extraction with dispersive liquid-liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m-cresol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid-liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid-liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1-3080 ng/g), low limits of detection (0.06-1.83 ng/g), and excellent reproducibility (

In this work, a miniaturized solid-phase extraction (SPE) platform, called sorbent membrane funnel, which permits in situ cleanup prior to membrane funnel-based spray analysis was developed. The fabrication of funnel and the mounting of SPE sorbent were simple and straightforward by a homemade punching system. Using different sorbents, the SPE sorbent funnel has been successfully applied in spray analysis of drug molecules spiked in human plasma, trypsin digested solution of bovine serum albumin in the presence of high concentration of chaotropic reagents, and phosphopeptides in the tryptic digested solution of casein. The results demonstrated that SPE sorbent attached membrane funnels can be a useful tool in common metabolomic and proteomic applications.

RATIONALE Samples analyzed in proteomic studies by nanoelectrospray ionization (nanoESI) are extremely limited in quantity requiring careful sample handling to prevent loss upon transfer and to maintain sample concentration. To alleviate the operational process and reduce the cost of nanoESI, it is essential to develop more robust, simple and sensitive analytical variants of the process. Membrane funnel-based spray was developed for analysis of proteins/peptides in this study. METHODS The membrane funnel was fabricated from thin flexible membrane by a punching method using a homemade device. The performance of the membrane funnel-based spray was demonstrated by analyzing peptides, proteins and trypsin-digested samples in comparison of nanoESI and the Teflon sheet based microfunnel. RESULTS Compared with the microfunnel, the membrane funnel can be fabricated easily by punching a thin flexible membrane using a sharp needle. Only 50 nL of sample was required for an analysis. The membrane funnel enhanced the spray sensitivity 100-fold. A total of 5 amol of on-spot sample loading was sufficient to provide a measurable signal on a 9.4 Tesla Fourier transform ion cyclotron resonance mass spectrometry system. High-mass proteins (up to 66 kDa) could be analyzed using this funnel-based spray system. Good sequence coverage was obtained for tryptic digested samples. CONCLUSIONS A rapid, simple and cheap membrane funnel-based sample plate fabrication method was developed. The membrane funnel-based spray is a promising new variant of nanoESI capable of fast and sensitive analysis of peptides/proteins with great potential that could be extended to other applications, including quantitative analysis at high throughput and imaging mass spectrometry.

Characterizing the structures of glycoconjungates is important because of glycan heterogeneity and structural complexity of aglycon. The presence of relatively weak glycosidic linkages leads to preferential cleavages that limit the acquisition of structural information under typical mass spectrometry dissociation conditions, such as collision-induced dissociation (CID) and infrared multiphoton dissociation. In this paper, we explored the dissociation behaviors of different members of glycoconjugates, including glycopeptides, glycoalkaloids, and glycolipids, under electron-induced dissociation (EID) conditions. Using CID spectra as references, we found that EID is not only a complementary method to CID, but also a method that can generate extensive fragment ions for the structural characterization of all intact glycoconjugates studied. Furthermore, isomeric ganglioside species can be differentiated, and the double bond location in the ceramide moiety of the gangliosides can be identified through the MS3 ap...

Our previous research found that culturable atrazine degraders associated with maize roots were dominated by genetically similar strains of Arthrobacter ureafaciens, suggesting their rhizosphere competence. The present study aimed to assess the root-colonizing capacity of strain A. ureafaciens DnL1-1 and to evaluate consequent root-associated degradation of atrazine. A soil-sand assay and pot experiments provided evidence that A. ureafaciens DnL1-1 competitively colonized roots of maize, wheat, and alfalfa following seed inoculation. Atrazine was not absolutely required but promoted colonization of plant roots by the bacterium. In association with plants, A. ureafaciens DnL1-1 enhanced the degradation of atrazine and strongly reduced accumulation of its dealkylated metabolites. Our results show that after low-level inoculation of seeds, the bacterium A. ureafaciens DnL1-1 can establish root populations sufficient for the rapid degradation of atrazine in soil that makes it a promising bioremediation agent which can be easily applied to large areas of polluted soil. Application of the root-colonizing, atrazine-degrading Arthrobacter bacteria as seed inoculants may be a reliable remediation strategy for soils contaminated with chlorinated s-triazines and their degradation products. Electronic supplementary material The online version of this article (doi:10.1007/s00253-017-8405-3) contains supplementary material, which is available to authorized users.

Using self-assembly gold nanoislands (SAM-AuNIs) functionalized by poly(m-phenylenediamine-co-aniline-2-sulfonic acid) (poly(mPD-co-ASA)) copolymer nanoparticles as specific receptors, a highly sensitive localized surface plasmon resonance (LSPR) optochemical sensor is demonstrated for detection of trace lead cation (Pb(II)) in drinking water. The copolymer receptor is optimized in three aspects: (1) mole ratio of mPD:ASA monomers, (2) size of copolymer nanoparticles, and (3) surface density of the copolymer. It is shown that the 95:5 (mPD:ASA mole ratio) copolymer with size less than 100 nm exhibits the best Pb(II)-sensing performance, and the 200 times diluted standard copolymer solution contributes to the most effective functionalization protocol. The resulting poly(mPD-co-ASA)-functionalized LSPR sensor attains the detection limit to 0.011 ppb toward Pb(II) in drinking water, and the linear dynamic range covers 0.011 to 5000 ppb (i.e., 6 orders of magnitude). In addition, the sensing system exhibits robust selectivity to Pb(II) in the presence of other metallic cations as well as common anions. The proposed functional copolymer functionalized on AuNIs is found to provide excellent Pb(II)-sensing performance using simple LSPR instrumentation for rapid drinking-water inspection.

This paper investigates the efficacy of zero-interest early payment financing (alternatively referred to as early payment) and positive-interest in-house factoring financing in a pull supply chain with a capital-constrained manufacturer selling a product through a capital-abundant retailer. Early payment is the prepayment of a wholesale cost to the manufacturer, whereas in-house factoring is a loan service provided to the manufacturer by a branch financing firm of the same retailer. We find that the retailer prefers early payment financing to bank financing when the manufacturer’s production cost is low. If the retailer instead offers positive-interest inhouse factoring financing to the manufacturer, then the financing equilibrium domain enlarges as compared to bank financing. Interestingly, early payment financing can outplay positive-interest in-house factoring financing if the production cost is considerably low; otherwise, vice versa. When the production cost is big enough, the retailer will not provide either early payment or in-house factoring. Furthermore, our main qualitative result sustains with an identical wholesale price across all three financing schemes and the financing equilibrium domain of early payment shrinks as demand variability grows.

Boron nitride nanotube (BNNT) is a novel material that shows potential ability in capturing organic pollutants. In this study, BNNTs fixed on a stainless steel fiber by a sol-gel technique were used as sorbent for solid-phase microextraction. Five polycyclic aromatic hydrocarbons with different numbers of aromatic rings were selected as target analysts. Gas chromatography coupled with tandem mass spectrometry was used for detection and quantitative determination. Under optimized conditions, the experimental results show a wide range of linearity (1 to 1,000 ng L(-1)), less than 10.1 % repeatability of relative standard deviation, and low detection limits (0.08 to 0.39 ng L(-1)). In addition, the fabricated fiber offered good thermal and chemical stability. The proposed method was successfully applied for the analysis of real water samples, and satisfactory results were obtained with relative recoveries ranging from 80.2 to 116.8 %. The results demonstrated that BNNTs could be used as sorbent for the analysis of environmental pollutants at trace levels.

The cytotoxic effects of thirteen triterpene glycosides from Holothuria scabra Jaeger and Cucumaria frondosa Gunnerus (Holothuroidea) against four human cell lines were detected and their cytotoxicity-structure relationships were established. The apoptosis-inducing activity of a more potent glycoside echinoside A (1) in HepG2 cells was further investigated by determining its effect on the morphology, mitochondrial transmembrane potential (Δψm) and mRNA expression levels of the apoptosis-related genes. The results showed that the number of glycosyl residues in sugar chains and the side chain of aglycone could affect their cytotoxicity towards tumor cells and selective cytotoxicity. 1 significantly inhibited cell viability and induced apoptosis in HepG2 cells. 1 also markedly decreased the Δψm and Bcl-2/Bax mRNA express ratio, and up-regulated the mRNA expression levels of Caspase-3, Caspase-8 and Caspase-9 in HepG2 cells. Therefore, 1 induced apoptosis in HepG2 cells through both intrinsic and extrinsic pathway. These findings could potentially promote the usage of these glycosides as leading compounds for developing new antitumor drugs.

We have investigated the feasibility of bamboo charcoal@iron oxide black for the headspace solid-phase microextraction of polychlorinated biphenyls in environmental water samples. Bamboo charcoal@iron oxide black was prepared and used as a solid-phase microextraction coating material, and gas chromatography with tandem mass spectrometry was used for detection. Several important factors affecting the extraction efficiency were systematically investigated and optimized. Under the optimum conditions, the experimental data exhibited wide linear range over the range 0.2-1000 ng/L and low limits of detection in the range of 4.7-22.2 pg/L. The novel coating was successfully used for the enrichment and determination of polychlorinated biphenyls in real environmental water samples. All these results indicated that bamboo charcoal@iron oxide black-based headspace solid-phase microextraction coupled to gas chromatography with tandem mass spectrometry was an excellent alternative for the sensitive analysis of polychlorinated biphenyls at ultratrace levels in the environment.

This study aims to investigate the feasibility of etched sand particles being used as solid-phase extraction adsorbents to enrich polychlorinated biphenyls (PCBs), which are typical persistent organic pollutants in the environment, at trace levels. Gas chromatography-tandem mass spectrometry was selected to detect the compounds. Etched sand particles exhibited excellent merits on the enrichment of PCBs. Related important factors affecting extraction efficiencies were investigated and optimized in detail. Under optimized conditions, low limits of detection (0.42 to 3.69 ng L(-1)), wide linear range (10 to 1,000 ng L(-1)), and high repeatability (1.9 to 8.2%) were achieved. The developed method was validated with several real water samples, and satisfactory results were obtained. All of these findings indicate that etched sand particles would be useful for the enrichment and determination of organic pollutants at trace levels in water samples.

Different from the short-term risk measure for traditional financial assets stocks, bonds, etc., the key to illiquid inventory portfolio traded in the over-the-counter markets is to estimate the long-term extreme price risk with time varying volatility. In this article, a new long-term extreme price risk value at risk and conditional value at risk measure method for inventory portfolio and an application to dynamic impawn rate interval are proposed. To realize this, we first establish AutoRegressive Moving Average-Exponential Generalized Autoregressive Conditional Heteroskedasticity-Extreme Value Theory model and multivariatet-Copula to depict the autocorrelation, fat tails, and volatility clustering of returns of inventories and the nonlinear dependence structure of inventories. Furthermore, we obtain the long-term extreme price risk with time varying volatility via Monte Carlo simulation instead of square-root-of time rule. The results show that, first, benefits from risk diversification is significant; second, long-term extreme price risk measure of inventory portfolio via Monte Carlo method outperforms the square-root-of time rule; the last is that the dynamic rate interval based on the long-term price risk is superior to the crude rules of thumb in terms of reducing efficiency loss and improving risk coverage. In summary, this article provides a new quantitative framework for managing the risk of portfolio in inventory financing practice for banks constrained by risk limitation. © 2014 Wiley Periodicals, Inc. Complexity 20: 17-34, 2015

All eight stereoisomers of saxagliptin have been synthesized and evaluated for their inhibitory activity against DPP-IV. It was unambiguously confirmed that the configuration of saxagliptin was critical to potent inhibition of DPP-IV. Docking study was performed to elucidate the configuration-activity relationship of saxagliptin stereoisomers. Tyr662 and Tyr470 have been suggested as the key residues of DPP-IV interacting with the inhibitors. This work provides valuable information for further inhibitor design against DPP-IV.

Understanding the adsorption behavior of chemical pollutant molecules on graphene surfaces is of both fundamental and practical importance for the application of graphene in environmental analysis. In this work, the mechanism and thermodynamics of adsorption of polybrominated diphenyl ethers (PBDEs) on graphene surfaces were studied by density functional theory and molecular dynamics methods. Nine types of PBDE molecules with different degrees of bromination and diphenyl ether (DE) molecules were selected as the adsorbates. It was found that the interaction strengths between the PBDE congeners (without 6 and 6′-substitution) and graphene increased with the degree of bromination. The adsorption energies of these systems also exhibited a positive linear correlation with the hydrophobicity of PBDE molecules, while for the other three PBDEs with 6 or 6′-substitution, the steric-hindrance effect leads to the molecules forming single π–π stacking interactions with the graphene surface and exhibiting a different adsorption behavior. The electronic density of states, charge transfer analysis and thermodynamic analysis indicated that the adsorption process of PBDEs on graphene is physisorption. The MD simulation indicates that graphene is sensitive to PBDE molecules and the adsorption process of PBDE on graphene is very fast. These findings will contribute to the understanding of the adsorption chemistry of aromatic pollutants on graphene-like nanomaterials.

A facile method of magnetic solid-phase extraction high-performance liquid chromatography-inductively coupled plasma mass spectrometry (MSPE-HPLC-ICP-MS) based on a magnetic adsorbent that was prepared by simply and directly adsorbing dithizone on the surface of the magnetite-reduced graphene oxide composites was developed to preconcentrate trace mercury species in environmental samples. Parameters influencing the synthesis of the adsorbents and extraction, including the ratio of GO to iron (III) acetylacetonate, solution pH, adsorption time, desorption time and the component of the eluent, were optimized. Under the optimized conditions, the enrichment factors were 400 and 380 (400 mL water sample) for inorganic mercury (IHg) and methylmercury (MMHg), respectively. The detection limits (3δ) of the proposed method were 0.48 and 0.17 ng L−1 for IHg and MMHg. The spiked recoveries (91.5–111%) and standard deviation (

This paper presents a case study on JD.com, one of the largest e-commerce platforms in China, to demonstrate how this online retailer enhances its competitive advantage by employing supply chain finance (SCF) practices to accelerate collaboration within the supply chain. Based on field interviews, this study investigates motivations and enabling factors for SCF adoption. Results show that JD adopts SCF mainly to strengthen its ecosystem and attain competitive advantage. In the sight of resource-based view and dynamic capability, JD builds an iterative process to conduct SCF practice. Enabling factors, mainly financial technology (fintech) and bargaining power, play critical roles in the decision-making process. The development of fintech facilitates the digitalization and capitalization process by improving transparency and efficiency while bargaining power influences the productization process. The adoption of SCF practice helps JD build closer partnership with supply chain partners and improves its own competitive advantage.

This study investigates the roles of bank and trade credits in a supply chain with a capital-constrained retailer facing demand uncertainty. We evaluate the retailer's optimal order quantity and the creditors' optimal credit limits and interest rates in two scenarios. In the single-credit scenario, we find the retailer prefers trade credit, if the trade credit market is more competitive than the bank credit market; otherwise, the retailer's preference of a specific credit type depends on the risk levels that the retailer would divert trade credit and bank credit to other risky investments. In the dual-credit scenario, if the bank credit market is more competitive than the trade credit market, the retailer first borrows bank credit prior to trade credit, but then switches to borrowing trade credit prior to bank credit as the retailer's internal capital declines. In contrast, if the trade credit market is more competitive, the retailer borrows only trade credit. We further analytically prove that the two credits are complementary if the retailer's internal capital is substantially low but become substitutable as the internal capital grows, and then empirically validate this prediction based on a panel of 674 firms in China over the period 2001�2007.

This study demonstrates the potential of bamboo charcoal as a novel and inexpensive solid-phase microextraction (SPME) coating material for enrichment and determination of organic pollutants in water samples. Bamboo charcoal was prepared and used as a SPME coating material. Eleven phthalate esters (PAEs) were used as model analytes, and gas chromatography-mass spectrometry was used for separation and detection. Important extraction conditions (ionic strength, stirring rate, and extraction time) and desorption conditions (desorption temperature and time) were systematically investigated and optimized. Linearity of 0.1-100 μg L(-1) and correlation coefficients of 0.9992-0.9998 were obtained under optimum conditions. Inter-day and intra-day repeatability were 2.15-9.93 % and 1.89-9.85 %, respectively, and fiber-to-fiber reproducibility was 5.42-9.66 %. On the basis of a chromatographic signal-to-baseline noise ratio of three, the limits of detection reached 0.004-0.023 μg L(-1). Satisfactory results were achieved when the bamboo coating was used for determination of 11 PAEs in real water samples. The experimental results indicate that bamboo charcoal has significant potential as a SPME coating material for rapid enrichment and sensitive determination of organic pollutants in environmental samples.

This paper evaluates both the optimal service level and optimal economic payout in service payout models. A service guarantee level is explicitly taken into consideration to obtain the optimal payout. In this study, we consider a generic model to provide insights into the dynamic interaction between the service guarantee and optimal payout levels. Parametric analyses show that when the demand payout coefficient is high, the impact of the payout is positive only if the payout rate is high enough.

3β-Hydroxy-12-oleanen-27-oic acid (ATA) was a main antitumor active triterpene from the rhizomes ofAstilbe chinensis. In this study, we investigated its effects on growth, apoptosis, cell cycle, motility/invasion, and metatasis in human hepatoma HepG2 cellsin vitroand antimetastasis of B16-F10 melanoma in micein vivo, as well as its molecular mechanisms of action using a high-throughput Cancer Pathway Finder PCR Array. ATA could not only induce tumor cells into apoptosis through the activation of both extrinsic and intrinsic pathways, arrest HepG2 cells in G2/M phase, but also suppress the invasion and metastasis abilities of HepG2 cells and the lung metastasis of B16-F10 melanoma in mice. PCR array assay revealed that ATA upregulated 9 genes including CDKN1A, MDM2, CFLAR (CASPER), TNFRSF10B (DR5), c-Jun, IL-8, THBS1, SERPINB5 (maspin), and TNF and downregulated 8 genes such as CCNE1, AKT, ANGPT1, TEK, TGFBR1, MMP9, U-PA, and S100A4. These results indicate that ATA could exert antitumor effects through activating JNK/MAPK and suppressing AKT signal transduction pathways and that ATA might be a potent anticancer agent.

Background Soil populations of bacteria rapidly degrading atrazine are critical to the environmental fate of the herbicide. An enrichment bias from the routine isolation procedure prevents studying the diversity of atrazine degraders. In the present work, we analyzed the occurrence, diversity and community structure of soil atrazine-degrading bacteria based on their direct isolation. Methods Atrazine-degrading bacteria were isolated by direct plating on a specially developed SM agar. The atrazine degradation genes trzN and atzABC were detected by multiplex PCR. The diversity of atrazine degraders was characterized by enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) genotyping followed by 16S rRNA gene phylogenetic analysis. The occurrence of atrazine-degrading bacteria was also assessed by conventional PCR targeting trzN and atzABC in soil DNA. Results A total of 116 atrazine-degrading isolates were recovered from bulk and rhizosphere soils sampled near an atrazine factory and from geographically distant maize fields. Fifteen genotypes were distinguished among 56 industrial isolates, with 13 of them representing eight phylogenetic groups of the genus Arthrobacter. The remaining two were closely related to Pseudomonas alcaliphila and Gulosibacter molinativorax and constituted major components of the atrazine-degrading community in the most heavily contaminated industrial plantless soil. All isolates from the adjacent sites inhabited by cogon grass or common reed were various Arthrobacter spp. with a strong prevalence of A. aurescens group. Only three genotypes were distinguished among 60 agricultural strains. Genetically similar Arthrobacter ureafaciens bacteria which occurred as minor inhabitants of cogon grass roots in the industrial soil were ubiquitous and predominant atrazine degraders in the maize rhizosphere. The other two genotypes represented two distant Nocardioides spp. that were specific to their geographic origins. Conclusions Direct plating on SM agar enabled rapid isolation of atrazine-degrading bacteria and analysis of their natural diversity in soil. The results obtained provided evidence that contaminated soils harbored communities of genetically distinct bacteria capable of individually degrading and utilizing atrazine. The community structures of culturable atrazine degraders were habitat-specific. Bacteria belonging to the genus Arthrobacter were the predominant degraders of atrazine in the plant rhizosphere. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0868-3) contains supplementary material, which is available to authorized users.

The practical applications of moisture sensitive metal-organic frameworks (MOFs) in the extraction technique are faced with avoided challenges related to competitive adsorption and hydrostability. The target analytes cannot be effectively extracted under humid conditions because of the competitive moisture adsorption and/or framework structure collapse of MOFs. In this Letter, metal-organic framework (MOF)@microporous organic network (MON) hybrid materials were explored for the first time as fiber coatings for solid-phase microextraction (SPME). Microporous materials with a hydrophobic surface was formed by coating the MOFs (MIL-101 and MOF-5) with MON through a sonogashira coupling reaction. MON acted as a hydrophobic "shield" to hinder the competitive moisture adsorption and improve moisture resistance and stability of the fiber. The sorbent exhibited higher enrichment factors (1215-3805) toward PAHs than other analytes in the water samples. An SPME method using MOF@MON-based fiber was developed to quantitatively determine PAHs. The proposed method was successfully applied to analyze PAHs in environmental water, particulate matter (PM

Hybrid graphene/h-BN sheet has been fabricated recently and verified to possess unusual physical properties. During the growth process, defects such as vacancies are unavoidably present at the interface between graphene and h-BN. In the present work, typical vacancy defects, which were located at the interface between graphene and h-BN, were studied by density functional theory. The interface structure, mechanical and electronic properties, and failure behavior of the hybrid graphene/h-BN sheet were investigated and compared. The results showed that the formation energy of the defective graphene/h-BN interface basically increased with increasing inflection angles. However, Young’s modulus for all graphene/h-BN systems studied decreased with the increase in inflection angles. The intrinsic strength of the hybrid graphene/h-BN sheets was affected not only by the inflection angles, but also by the type of interface connection and the type of defects. The energy band structure of the hybrid interface could be tuned by applying mechanical strain to the systems. These results demonstrated that vacancies introduced significant effects on the mechanical and electronic properties of the hybrid graphene/h-BN sheet.

In this work, a core-shell Fe3O4@SiO2@MOF/TiO2 nanocomposite was synthesized and used to as adsorbent for magnetic solid-phase extraction (MSPE) of triazole fungicides from environmental water samples. Five triazole fungicides, namely, triadimenol, hexaconazole, diniconazole, myclobutanil, and tebuconazole, were selected as target analytes for MSPE. These analytes were quantitatively adsorbed on microspheres, and the sorbents were separated from the solution by using a magnet. The analytes were desorbed by methanol and determined through liquid-chromatography coupled with tandem mass spectrometry. The extraction parameters affecting the extraction efficiency were optimized through response surface methodology. The limits of detection and limits of quantification for the selected fungicides were 0.19-1.20ngL(-1) and 0.61-3.62ngL(-1), respectively. The proposed method was applied to determine the concentration of fungicides in actual environmental water samples. The accuracy of the proposed method was evaluated by measuring the recovery of the spiked samples. The satisfying recoveries of the four water samples ranged from 90.2% to 104.2%. Therefore, the magnetic metal-organic framework/TiO2 nanocomposite based MSPE is a potential approach to analyze fungicides in actual water samples.

The adsorptive potential of hexagonal boron nitride nanosheets (h-BNNSs) for solid-phase extraction (SPE) of pollutants was investigated for the first time. Seven indicators of polychlorinated biphenyls (PCBs) were selected as target analytes. The adsorption of PCBs on the surface of the h-BNNSs in water was simulated by the density functional theory and molecular dynamics. The simulation results indicated that the PCBs are adsorbed on the surface by π-π, hydrophobic, and electrostatic interactions. The PCBs were extracted with an h-BNNS-packed SPE cartridge, and eluted by dichloromethane. Gas chromatography-tandem mass spectrometry working in the multiple reaction monitor mode was used for the sample quantification. The effect of extraction parameters, including the flow rate, pH value, breakthrough volume, and the ionic strength, were investigated. Under the optimal working conditions, the developed method showed low limits of detection (0.24-0.50 ng L(-1); signal-to-noise ratio = 3:1), low limits of quantification (0.79-1.56 ng L(-1); signal-to-noise ratio = 10:1), satisfactory linearity (r 0.99) within the concentration range of 2-1000 ng L(-1), and good precision (relative standard deviation 12%). The PCBs concentration in environmental water samples was determined by the developed method. This results demonstrate that h-BNNSs have high analytical potential in the enrichment of pollutants.

Two series of novel tricyclic oxazine and oxazepine fused quinazolines have been designed and synthesized. The in vitro antitumor effect of the title compounds was screened on N87, A431, H1975, BT474 and Calu-3 cell lines. Compared to gefitinib and erlotinib, compounds 1a-1h were found to demonstrate more potent antitumor activities. Several derivatives could counteract EGF-induced phosphorylation of EGFR in cells, and their potency was comparable to the reference compounds. Compounds 1a-1f, 1h were chosen for further evaluation of EGFR and HER2 in vitro kinase inhibitory activity. Compounds 1c-1f, 1h effectively inhibited the in vitro kinase activity of EGFR and HER2 with similar efficacy as gefitinib and erlotinib.

PtSn alloy, which is a potential material for use in direct methanol fuel cells, can efficiently promote methanol oxidation and alleviate the CO poisoning problem. Herein, methanol decomposition on Pt3Sn(111) was systematically investigated using periodic density functional theory and microkinetic modeling. The geometries and energies of all of the involved species were analyzed, and the decomposition network was mapped out to elaborate the reaction mechanisms. Our results indicated that methanol and formaldehyde were weakly adsorbed, and the other derivatives (CHxOHy, x = 1-3, y = 0-1) were strongly adsorbed and preferred decomposition rather than desorption on Pt3Sn(111). The competitive methanol decomposition started with the initial O-H bond scission followed by successive C-H bond scissions, (i.e., CH3OH → CH3O → CH2O → CHO → CO). The Brønsted-Evans-Polanyi relations and energy barrier decomposition analyses identified the C-H and O-H bond scissions as being more competitive than the C-O bond scission. Microkinetic modeling confirmed that the vast majority of the intermediates and products from methanol decomposition would escape from the Pt3Sn(111) surface at a relatively low temperature, and the coverage of the CO residue decreased with an increase in the temperature and decrease in partial methanol pressure.

In this work, the thermo-responsive polymer PNIPAM tethered to Fe3O4@SiO2@MOF core-shell magnetic microspheres was first synthesized by a surface-selective post-synthetic strategy and underwent highly efficient magnetic solid-phase extraction (MSPE) of alkylphenols from aqueous samples. Alkylphenols, including 4-tert-octylphenol (OP) and 4-n-nonylphenol (NP), were selected as target compounds. The sample quantification was carried out using LC-MS/MS in multiple reaction monitor (MRM) mode. Under optimal working conditions, the developed method showed good linearity in the range of 5-1000ngL(-1), a low limit of detection (1.5ngL(-1)), and good repeatability (relative standard deviation

To discuss the efficacy and safety of microsurgical varicocelectomy combined with aescine in the treatment of varicocele.A total of 120 patients with varicocele received treatments and follow up in Shanghai Renji Hospital and Shanghai General Hospital between September 2013 and April 2015, 63 patients of which were infertile and 57 patients of which were painful varicocele. A total of 106 patients were unilateral varicocele and 14 patients were bilateral varicocele. Forty-one patients were treated with varicocelectomy, and 79 patients were treated with varicocelectomy combined with aescine, 300 mg, twice a day, orally. Sperm analysis, pregnancy rate, sex hormone, and complications were recorded after six months treatments.There was significant difference in the sperm motility improvement in infertile patients between microsurgical group (60.0%, 12/20) and combined therapy group (83.7%, 36/43) (P0.05). There was no significant difference in levels of sexual hormones in infertile patients between microsurgical group and combined therapy group (luteinizing hormone (4.07 ± 1.49) vs (4.29 ± 1.32) U/L, follicule-stimulating hormone (5.64 ± 2.70) vs (5.11 ± 1.25) U/L, and testosterone (16.09 ± 2.25) vs (15.98 ± 3.79) µg/L). The pregnancy rate of infertile patients in microsurgical group and combined therapy group were 15.0% (3/20) and 18.6% (8/43), respectively, with no statistic difference between these two groups (P0.05). The total improvement rates for the pain resolution in microsurgical group and combined therapy group were 76.2% (16/21) and 94.4% (34/36), respectively, with statistic difference between these two groups (P0.05). In the microsurgical group, there were two cases of scrotal edema and one case of reoccurrence after treatment, while no complications were appeared in the combined therapy group.Microsurgical varicocelectomy combined with aescine could improve sperm quality, relieve pain, and prevent complications occurrence to some extent compared with microsurgical varicocelectomy. Microsurgical varicocelectomy combined with aescine could be applied in clinical varicocele treatment.

Conditions of HPLC and parameters of MS/MS. (DOC 76Â kb)

Soil characteristics. (DOC 50Â kb)

The reactions of Sc+ (3D, 1D) and Fe+ (6D, 4 F) with acetone have been investigated in both high- and low-spin states using density functional theory. Our calculations have indicated that oxidation of Sc+ by acetone can take place by (1) metal-mediated H migration, (2) direct methyl-H shift and/or (3) C = O insertion. The most energetically favorable pathway is metal-mediated H migration followed by intramolecular ScO+ rotation and dissociation. For the deethanization of acetone mediated by Fe+, the reaction occurs on either the quartet or sextet surfaces through five elementary steps, i.e. encounter complexation, C–C bond activation, methyl migration, C–C coupling and non-reactive dissociation. The rate-determining step along the quartet-state potential-energy surface (PES) is similar to that in the case of Ni+ (2 F, 3d9), namely the methyl-migration step. For the sextet-state PES, however, the energy barrier for methyl migration is lower than that for C–C bond activation, and the rate-determining step is C–C coupling. In general, the low-spin-state pathways are lower in energy than the high-spin-state pathways; therefore, the reaction pathways for the oxidation of Sc+ and the Fe+-mediated deethanization of acetone mostly involve the low-spin states. Copyright © 2012 John Wiley & Sons, Ltd.

Poly(vinyl alcohol)/graphene oxide (PVA/GO) composites were studied by molecular mechanics and molecular dynamics methods to analyze the effect of GO sheet addition on PVA material. The properties ...

The paper investigates the impacts of trade credit (i.e., open account payment) and limited liability on the performance of a two-level supply chain with budget constraints. It shows that limited liability accounts for the reason why the retailer with a lower initial budget initiates a higher ordering level under trade credit contract. Furthermore, this paper finds that trade credit contract could create value in a supply chain with budget constraints, and partly coordinate the supply chain.

There exist capital constraints in many distribution channels. We examine a channel consisting of one manufacturer and one retailer, where the retailer is capital constrained. The retailer may fund its business by borrowing credit either from a competitive bank market or from the manufacturer, provided the latter is willing to lend. When only one credit type (either bank or trade credit) is viable, we show that trade credit financing generally charges a higher wholesale price and thus becomes less attractive than bank credit financing for the retailer. When both bank and trade credits are viable, the unique equilibrium is trade credit financing if production cost is relatively low but is bank credit financing otherwise. We also study the case where both the retailer and the manufacturer are capital constrained and demonstrate that, to improve the overall supply chain efficiency, the bank should finance the manufacturer if production cost is low but finance the retailer otherwise. Our analysis further suggests that the equilibrium region of trade credit financing shrinks as demand variability or the retailer's internal capital level increases.