Biogeography of the large intestinal mucosal and luminal microbiome in cynomolgus macaques with depressive-like behavior.

Most previous studies in the pathophysiology of major depressive disorder (MDD) focused on fecal samples, which limit the identification of the gut mucosal and luminal microbiome in depression. Here, we address this knowledge gap. Male cynomolgus macaques (Macaca fascicularis) were randomly assigned to a chronic unpredictable mild stress (CUMS) group, or to an unstressed control group. Behavioral tests were completed in both groups. At endpoint, microbe composition of paired mucosal and luminal samples from cecum, ascending, transverse, and descending colons were determined by 16S ribosomal RNA gene sequencing. The levels of 34 metabolites involved in carbohydrate or energy metabolism in luminal samples were measured by targeted metabolomics profiling. CUMS macaques demonstrated significantly more depressive-like behaviors than controls. We found differences in mucosal and luminal microbial composition between the two groups, which were characterized by Firmicutes and Bacteriodetes at the phylum level, as well as Prevotellaceae and Lachnospiraceae at the family level. The majority of discriminative microbes correlated with the depressive-like behavioral phenotype. In addition, we found 27 significantly different microbiome community functions between the two groups in mucosa, and one in lumen, which were mainly involved in carbohydrate and energy metabolism. A total of nine metabolites involved in these pathways were depleted in CUMS animals. Together, CUMS macaques with depressive-like behaviors associated with distinct alterations of covarying microbiota, carbohydrate and energy metabolism in mucosa and lumen. Further studies should focus on the mucosal and luminal microbiome to provide a deeper spatiotemporal perspective of microbial alterations in the pathogenesis of MDD.

Metal Oxide-Based Selective Enrichment Combined with Stable Isotope Labeling-Mass Spectrometry Analysis for Profiling of Ribose Conjugates.

Some modified ribonucleosides in biological fluids have been evaluated as cancer-related metabolites. Detection of endogenous modified ribonucleosides in biological fluids may serve as a noninvasive cancers diagnostic method. However, determination of modified ribonucleosides is still challenging because of their low abundance and serious matrix interferences in biological fluids. Here, we developed a novel strategy for comprehensive profiling of ribose conjugates from biological fluids using metal oxide-based dispersive solid-phase extraction (DSPE) followed with in vitro stable isotope labeling and double neutral loss scan-mass spectrometry analysis (DSPE-SIL-LC-DNLS-MS). Cerium dioxide (CeO2) was used to selectively recognize and capture ribose conjugates from complex biological samples under basic environment. The enriched ribose conjugates were subsequently labeled with a pair of isotope labeling reagents (acetone and acetone-d6). The glucosidic bond of acetone labeled ribose conjugates is readily ruptured, and the generated ribose that carries an isotope tag can be lost as a neutral fragment under collision induced dissociation (CID). Since the light (acetone) and heavy (acetone-d6) labeled compounds have the same chemical structures and can generate different neutral loss fragments (NL 172 and 178 Da), it is therefore highly convenient to profile ribose conjugates by double neutral loss scan mode in mass spectrometry analysis. In this respect, the light and heavy labeled compounds were ionized at the same condition but recorded separately on MS spectra, which can significantly improve the detection specificity and facilitate the identification of ribose conjugates. Using the developed DSPE-SIL-LC-DNLS-MS strategy, we profiled the ribose conjugates in human urine, and 49 ribose conjugates were readily identified, among which 7 ribose conjugates exhibited significant contents change between healthy controls and lymphoma patients. The DSPE-SIL-LC-DNLS-MS strategy combines the selective enrichment, stable isotope labeling, and double neutral loss scan - MS analysis, which therefore can efficiently minimize false positive results, facilitate the relative quantification, and notably increase the numbers of identified ribose conjugates in biological fluids samples. Taken together, this study established a promising strategy for the effective profiling of urinary modified ribonucleosides, and simultaneous evaluation of the contents change of multiple modified ribonucleosides should provide more accurate and conclusive results for the use of urinary modified ribonucleosides as indicators of cancers.

Functional inactivation of UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1) induces early leaf senescence and defence responses in rice.

Plant leaf senescence and defence responses are important biological processes, but the molecular mechanisms involved are not well understood. This study identified a new rice mutant, spotted leaf 29 (spl29). The SPL29 gene was identified by map-based cloning, and SPL29 was confirmed as UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1) by enzymatic analysis. The mutant spl29 lacks UAP activity. The biological phenotypes for which UAP is responsible have not previously been reported in plants. The spl29 mutant displayed early leaf senescence, confirmed by chlorophyll loss and photosystem II decline as physiological indicators, chloroplast degradation as a cellular characteristic, and both upregulation of senescence transcription factors and senescence-associated genes, and downregulation of photosynthesis-related genes, as molecular evidence. Defence responses were induced in the spl29 mutant, shown by enhanced resistance to bacterial blight inoculation and upregulation of defence response genes. Reactive oxygen species, including O2 (-) and H2O2, accumulated in spl29 plants; there was also increased malondialdehyde content. Enhanced superoxide dismutase activity combined with normal catalase activity in spl29 could be responsible for H2O2 accumulation. The plant hormones jasmonic acid and abscisic acid also accumulated in spl29 plants. ROS and plant hormones probably play important roles in early leaf senescence and defence responses in the spl29 mutant. Based on these findings, it is suggested that UAP1 is involved in regulating leaf senescence and defence responses in rice.

Coupling carbon nanotube film microextraction with desorption corona beam ionization for rapid analysis of Sudan dyes (I-IV) and Rhodamine B in chilli oil.

A rapid analysis method by coupling carbon nanotube film (CNTF) microextraction with desorption corona beam ionization (DCBI) was developed for the determination of Sudan dyes (I-IV) and Rhodamine B in chilli oil samples. Typically, CNTF was immersed into the diluted solution of chilli oil for extraction, which was then placed directly under the visible plasma beam tip of the DCBI source for desorption and ionization. Under optimized conditions, five dyes were simultaneously determined using this method. Results showed that the analytes were enriched by the CNTF through the π-π interactions, and the proposed method could significantly improve the sensitivities of these compounds, compared to the direct analysis by DCBI-MS/MS. The method with a linear range of 0.08-12.8 µg g(-1) and good linear relationships (R(2) > 0.93) in a multiple reaction monitoring (MRM) mode was developed. Satisfactory reproducibility was achieved. Relative standard deviations (RSDs) were less than 20.0%. The recoveries ranged from 80.0 to 110.0%, and the limits of detection (LODs) were in the range of 1.4-21 ng g(-1). Finally, the feasibility of the method was further exhibited by the determination of five illegal dyes in chilli powder. These results demonstrate that the proposed method consumes less time and solvent than conventional HPLC-based methods and avoids the contamination of chromatographic column and ion source from non-volatile oil. With the help of a 72-well shaker, multiple samples could be treated simultaneously, which ensures high throughput for the entire pretreatment process. In conclusion, it provides a rapid and high-throughput approach for the determination of such illicit additions in chilli products.

Magnetic solid phase extraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human body fluids.

Ambient ionization techniques show good potential in rapid analysis of target compounds. However, a direct application of these ambient ionization techniques for the determination of analytes in a complex matrix is difficult due to the matrix interference and ion suppression. To resolve this problem, here we developed a strategy by coupling magnetic solid phase extraction (MSPE) with desorption corona beam ionization (DCBI)-mass spectrometry (MS). As a proof of concept, the pyrrole-coated Fe3O4 magnetic nanoparticles (Fe3O4@Ppy) were prepared and used for the extraction of antidepressants. After extraction, the Fe3O4@Ppy with trapped antidepressants was then directly subjected to DCBI-MS analysis with the aid of a homemade magnetic glass capillary. As the MSPE process is rapid and the direct DCBI-MS analysis does not need solvent desorption or chromatographic separation processes, the overall analysis can be completed within 3 min. The proposed MSPE-DCBI-MS method was then successfully used to determine antidepressants in human urine and plasma. The calibration curves were obtained in the range of 0.005-0.5 µg mL(-1) for urine and 0.02-1 µg mL(-1) for plasma with reasonable linearity (R(2) > 0.951). The limits of detection of three antidepressants were in the range of 0.2-1 ng mL(-1) for urine and 2-5 ng mL(-1) for plasma. Acceptable reproducibility for rapid analysis was achieved with relative standard deviations less than 19.1% and the relative recoveries were 85.2-118.7%. Taken together, the developed MSPE-DCBI-MS strategy offers a powerful capacity for rapid analysis of target compounds in a complex matrix, which would greatly expand the applications of ambient ionization techniques with plentiful magnetic sorbents.

Profiling of thiol-containing compounds by stable isotope labeling double precursor ion scan mass spectrometry.

Here we developed a novel strategy of isotope labeling in combination with high-performance liquid chromatography-double precursor ion scan mass spectrometry (IL-LC-DPIS-MS) analysis for nontargeted profiling of thiol-containing compounds. In this strategy, we synthesized a pair of isotope labeling reagents (ω-bromoacetonylquinolinium bromide, BQB; ω-bromoacetonylquinolinium-d7 bromide, BQB-d7) that contain a reactive group, an isotopically labeled moiety, and an ionizable group to selectively label thiol-containing compounds. The BQB and BQB-d7 labeled compounds can generate two characteristic product ions m/z 218 and 225, which contain an isotope tag and therefore were used for double precursor ion scans in mass spectrometry analysis. The peak pairs with characteristic mass differences can be readily extracted from the two precursor ion scan (PIS) spectra and assigned as potential thiol-containing candidates, which facilitates the identification of analytes. BQB and BQB-d7 labeled thiol-containing compounds can be clearly distinguished by generating two individual ion chromatograms. Thus, thiol-containing compounds from two samples labeled with different isotope reagents are ionized at the same time but recorded separately by mass spectrometry, offering good identification and accurate quantification by eliminating the MS response fluctuation and mutual interference from the two labeled samples. Using the IL-LC-DPIS-MS strategy, we profiled the thiol-containing compounds in beer and human urine, and 21 and 103 thiol candidates were discovered in beer and human urine, respectively. In addition, 9 and 17 thiol candidates in beer and human urine were successfully identified by further comparison with thiol standards or tandem mass spectrometry analysis. Taken together, the IL-LC-DPIS-MS method is demonstrated to be a promising strategy in the profiling of compounds with identical groups in metabolomics study.

Mutation of rice BC12/GDD1, which encodes a kinesin-like protein that binds to a GA biosynthesis gene promoter, leads to dwarfism with impaired cell elongation.

The kinesins are a family of microtubule-based motor proteins that move directionally along microtubules and are involved in many crucial cellular processes, including cell elongation in plants. Less is known about kinesins directly regulating gene transcription to affect cellular physiological processes. Here, we describe a rice (Oryza sativa) mutant, gibberellin-deficient dwarf1 (gdd1), that has a phenotype of greatly reduced length of root, stems, spikes, and seeds. This reduced length is due to decreased cell elongation and can be rescued by exogenous gibberellic acid (GA3) treatment. GDD1 was cloned by a map-based approach, was expressed constitutively, and was found to encode the kinesin-like protein BRITTLE CULM12 (BC12). Microtubule cosedimentation assays revealed that BC12/GDD1 bound to microtubules in an ATP-dependent manner. Whole-genome microarray analysis revealed the expression of ent-kaurene oxidase (KO2), which encodes an enzyme involved in GA biosynthesis, was downregulated in gdd1. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed that GDD1 bound to the element ACCAACTTGAA in the KO2 promoter. In addition, GDD1 was shown to have transactivation activity. The level of endogenous GAs was reduced in gdd1, and the reorganization of cortical microtubules was altered. Therefore, BC12/GDD1, a kinesin-like protein with transcription regulation activity, mediates cell elongation by regulating the GA biosynthesis pathway in rice.

Isotope labelling--paired homologous double neutral loss scan-mass spectrometry for profiling of metabolites with a carboxyl group.

We developed a novel method for non-targeted screening of metabolites by high performance liquid chromatography-mass spectrometry with paired homologous double neutral loss scan mode after in vitro isotope labelling (IL-HPLC-PHDNL-MS). As a proof of concept, we investigated the carboxylic acid metabolite profiling in plant samples by the IL-HPLC-PHDNL-MS method. To this end, N,N-dimethylaminobutylamine (DMBA) and d(4)-N,N-dimethylaminobutylamine (d(4)-DMBA) were synthesized and utilized to label carboxylic acids. Our results show the MS response of carboxylic acids was enhanced by 20- to 40-fold after labelling. As for the IL-HPLC-PHDNL-MS analysis, DMBA and d(4)-DMBA labelled samples were mixed equally before MS analysis. Because the isotope labelled moieties (dimethylamino moiety, Me2N) of DMBA and d(4)-DMBA are easily ruptured and lost as neutral fragments (NL 45 and NL 49) under collision induced dissociation (CID), two neutral loss scans can be carried out simultaneously to record the signals of DMBA and d(4)-DMBA labelled samples, respectively. In this respect, the metabolites from two samples labelled with different isotope reagents are ionized at the same time but recorded separately by mass spectrometry, which can eliminate the MS response fluctuation and mutual interference. Using this method, six potential biomarkers involved in wounded tomato leaves were identified, and their structures were further elucidated by product ion scan and high resolution mass spectrometry analysis. Taken together, the IL-HPLC-PHDNL-MS method demonstrated good performance on the identification as well as relative quantification of metabolites with a carboxyl group in biological samples.

Alterations of mitochondrial protein assembly and jasmonic acid biosynthesis pathway in Honglian (HL)-type cytoplasmic male sterility rice.

It has been suggested that the mitochondrial chimeric gene orfH79 is the cause for abortion of microspores in Honglian cytoplasmic male sterile rice, yet little is known regarding its mechanism of action. In this study, we used a mass spectrometry-based quantitative proteomics strategy to compare the mitochondrial proteome between the sterile line Yuetai A and its fertile near-isogenic line Yuetai B. We discovered a reduced quantity of specific proteins in mitochondrial complexes in Yuetai A compared with Yuetai B, indicating a defect in mitochondrial complex assembly in the sterile line. Western blotting showed that ORFH79 protein and ATP1 protein, an F(1) sector component of complex V, are both associated with large protein complexes of similar size. Respiratory complex activity assays and transmission electron microscopy revealed functional and morphological defects in the mitochondria of Yuetai A when compared with Yuetai B. In addition, we identified one sex determination TASSELSEED2-like protein increased in Yuetai A, leading to the discovery of an aberrant variation of the jasmonic acid pathway during the development of microspores.

Overexpression of rice LRK1 restricts internode elongation by down-regulating OsKO2.

Rice (Oryza sativa) has the potential to undergo rapid internodal elongation which determines plant height. Gibberellin is involved in internode elongation. Leucine-rich repeat receptor-like kinases (LRR-RLKs) are the largest subfamily of transmembrane receptor-like kinases in plants. LRR-RLKs play important functions in mediating a variety of cellular processes and regulating responses to environmental signals. LRK1, a PSK receptor homolog, is a member of the LRR-RLK family. In the present study, differences in ectopic expression of LRK1 were consistent with extent of rice internode elongation. Analyses of gene expression demonstrated that LRK1 restricts gibberellin biosynthesis during the internode elongation process by down-regulation of the gibberellin biosynthetic gene coding for ent-kaurene oxidase.

Rice ethylene-response AP2/ERF factor OsEATB restricts internode elongation by down-regulating a gibberellin biosynthetic gene.

Plant height is a decisive factor in plant architecture. Rice (Oryza sativa) plants have the potential for rapid internodal elongation, which determines plant height. A large body of physiological research has shown that ethylene and gibberellin are involved in this process. The APETALA2 (AP2)/Ethylene-Responsive Element Binding Factor (ERF) family of transcriptional factors is only present in the plant kingdom. This family has various developmental and physiological functions. A rice AP2/ERF gene, OsEATB (for ERF protein associated with tillering and panicle branching) was cloned from indica rice variety 9311. Bioinformatic analysis suggested that this ERF has a potential new function. Ectopic expression of OsEATB showed that the cross talk between ethylene and gibberellin, which is mediated by OsEATB, might underlie differences in rice internode elongation. Analyses of gene expression demonstrated that OsEATB restricts ethylene-induced enhancement of gibberellin responsiveness during the internode elongation process by down-regulating the gibberellin biosynthetic gene, ent-kaurene synthase A. Plant height is negatively correlated with tiller number, and higher yields are typically obtained from dwarf crops. OsEATB reduces rice plant height and panicle length at maturity, promoting the branching potential of both tillers and spikelets. These are useful traits for breeding high-yielding crops.

Tomato SlDREB gene restricts leaf expansion and internode elongation by downregulating key genes for gibberellin biosynthesis.

Plants have evolved and adapted to different environments. Dwarfism is an adaptive trait of plants that helps them avoid high-energy costs under unfavourable conditions. The role of gibberellin (GA) in plant development has been well established. Several plant dehydration-responsive element-binding proteins (DREBs) have been identified and reported to be induced under abiotic and biotic stress conditions. A tomato DREB gene named SlDREB, which is a transcription factor and was cloned from cultivated tomato M82, was found to play a negative role in tomato plant architecture and enhances drought tolerance. Tissue expression profiles indicated that SlDREB was expressed mainly in the stem and leaf and could be induced by abscisic acid (ABA) but suppressed by GA and ethylene. SlDREB altered plant morphology by restricting leaf expansion and internode elongation when overexpressed, and the resulting dwarfism of tomato plants could be recovered by application of exogenous gibberellic acid (GA(3)). Transcriptional analysis of transgenic plants revealed that overexpression of SlDREB caused the dwarf phenotype by downregulating key genes involved in GA biosynthesis such as ent-copalyl diphosphate synthase (SlCPS) and GA 20-oxidases (SlGA20ox1, -2, and -4), thereby decreasing endogenous GA levels in transgenic plants. A yeast activity assay demonstrated that SlDREB specifically bound to dehydration-responsive element/C-repeat (DRE/CRT) elements of the SlCPS promoter region. Taken together, these data demonstrated that SlDREB can downregulate the expression of key genes required for GA biosynthesis and that it acts as a positive regulator in drought stress responses by restricting leaf expansion and internode elongation.

Sample preparation and direct electrospray ionization on a tip column for rapid mass spectrometry analysis of complex samples.

A handheld pipette tip column electrospray ionization source (PTC-ESI source) was developed for rapid mass spectrometry analysis at ambient pressure. The PTC-ESI source was made up of three main component parts including a micro DC high voltage (HV) power supply, a micropipette and a disposable micropipette tip filled with a plug of adsorbent. A DC high voltage was applied to the sharp point of the micropipette tip column to induce electrospray ionization. The PTC-ESI source was successfully used for direct analysis of basic organic compounds, organic acids and peptides in a simple matrix. In the case of complex samples, micro-extraction based on the adsorbent phase filled in the pipette tip was used to remove impurities and concentrate target analytes prior to ionization. The eluting solution was not pipetted out, but directly dispersed in the form of electrospray from the pipette tip for ionization. The effectiveness of the PTC-ESI source has been further demonstrated by fast analysis of therapeutic compounds and endogenous bioactive chemicals in complex biological samples.

Use of isotope differential derivatization for simultaneous determination of thiols and oxidized thiols by liquid chromatography tandem mass spectrometry.

Here we report a new isotopic pair of derivatization reagents, ω-bromoacetonylquinolinium bromide (BQB) and d(7)-ω-bromoacetonylquinolinium bromide (d(7)-BQB). BQB and d(7)-BQB both rapidly and selectively reacted with thiols in acidic medium within 3min with the aid of a microwave. Reduced thiols and total thiols in urine were labeled with BQB and d(7)-BQB, respectively. The BQB- and d(7)-BQB-labeled urine samples were then mixed and separated on a HILIC (hydrophilic interaction chromatography) column followed by electrospray ionization tandem mass spectrometry (ESI-MS/MS) detection. The new strategy, which we have named isotope differential derivatization, allows us to simultaneously determine thiols and oxidized thiols in a single run. Compared with positive mode ESI detection of unlabeled thiols, the positive mode ESI-MS signal intensities of BQB-labeled thiols were found to increase by 10-, 20-, and 40-fold for cysteine (Cys), homocysteine (HCys), and glutathione (GSH), respectively (unlabeled N-acetylcysteine (Nac) is difficult to detect by ESI-MS in positive mode due to its low ionization efficiency). The detection limits calculated at a signal-to-noise ratio of 3 were found to be 8.02, 1.56, 0.833, and 3.27nmol/L for Cys, HCys, Nac, and GSH, respectively. Recoveries of thiols and disulfides from spiked urine samples were between 80% and 105%. The method was successfully used to determine thiols and oxidized thiols in urine samples of 25 healthy volunteers.

Use of isotope mass probes for metabolic analysis of the jasmonate biosynthetic pathway.

In order to quantitatively study the jasmonate biosynthetic pathway, we chemically synthesized a pair of isotope mass probes and established a labeling protocol. The pair of mass probes used in our work were ω-bromoacetonylpyridinium bromide (BPB) and d(5)-ω-bromoacetonylpyridinium bromide (d(5)-BPB), which contain carboxylic acid reactive groups, isotopically labeled groups and permanent positive charges. High performance liquid chromatography (HPLC) and electrospray ionization quadrupole-time of flight mass spectrometry (ESI-QTOF-MS) were used for the detection of labeled standard mixtures and plant samples. In comparison to negative mode electrospray ionization detection of unlabeled analytes, the ESI signal of reverse charge labeled compounds was shown to improve by 20- to 80-fold. Accurate relative quantification was achieved as no isotopic effects of the different isotope labeled phytohormones during RP/SCX mixed-mode liquid chromatographic separation were observed. A data analysis method was established for analyzing metabolic pathways using our labeling strategy. We then applied our method and examined the jasmonate biosynthetic pathway of rice under salt stress and the premature senescence mutant. Here we found that under salt stress conditions, rice showed up-regulation in (13S)-hydroperoxyoctadecatrienoic acid (HOPT), cis-(+)-12-oxophytodienoic acid (OPDA), 3-oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic acid (OPC-8) and jasmonoyl-valine (JA-Val) levels, while α-linolenic acid (LA) and jasmonic acid (JA) showed down-regulation, and three components (HPOT, OPC-8 and JA-Val) were accumulated. The premature senescence mutant showed up-regulation in all major components of the jasmonate biosynthetic pathway with the exception of LA, and an accumulation of HPOT, OPC-6 and JA-Val. This study demonstrates that our chemical stable isotope labeling strategy can be used as a powerful tool for metabolic pathway analysis of phytohormones in plants.

Molecular Dynamics Simulations of the Oil-Detachment from the Hydroxylated Silica Surface: Effects of Surfactants, Electrostatic Interactions, and Water Flows on the Water Molecular Channel Formation.

The detachment process of an oil molecular layer situated above a horizontal substrate was often described by a three-stage process. In this mechanism, the penetration and diffusion of water molecules between the oil phase and the substrate was proposed to be a crucial step to aid in removal of oil layer/drops from substrate. In this work, the detachment process of a two-dimensional alkane molecule layer from a silica surface in aqueous surfactant solutions is studied by means of molecular dynamics (MD) simulations. By tuning the polarity of model silica surfaces, as well as considering the different types of surfactant molecules and the water flow effects, more details about the formation of water molecular channel and the expansion processes are elucidated. It is found that for both ionic and nonionic type surfactant solutions, the perturbation of surfactant molecules on the two-dimensional oil molecule layer facilitates the injection and diffusion of water molecules between the oil layer and silica substrate. However, the water channel formation and expansion speed is strongly affected by the substrate polarity and properties of surfactant molecules. First, only for the silica surface with relative stronger polarity, the formation of water molecular channel is observed. Second, the expansion speed of the water molecular channel upon the ionic surfactant (dodecyl trimethylammonium bromide, DTAB and sodium dodecyl benzenesulfonate, SDBS) flooding is more rapidly than the nonionic surfactant system (octylphenol polyoxyethylene(10) ether, OP-10). Third, the water flow speed may also affect the injection and diffusion of water molecules. These simulation results indicate that the water molecular channel formation process is affected by multiple factors. The synergistic effects of perturbation of surfactant molecules and the electrostatic interactions between silica substrate and water molecules are two key factors aiding in the injection and diffusion of water molecules and helpful for the oil detachment from silica substrate.

Parameter Identification of an Ultrafiltration Model for Organics Removal in a Full-Scale Wastewater Reclamation Plant with Sparse and Incomplete Monitoring Data.

Ultrafiltration (UF) has become one of the dominant treatment processes for wastewater reclamation in China. Modeling is an effective instrument to understand and optimize UF systems. To this end, a previously developed UF model for organics removal was applied to the UF process in a typical, full-scale wastewater reclamation plant (WRP) in China. However, the sparse and incomplete field monitoring data from the studied WRP made the traditional model analysis approaches hardly work in this case. Therefore, two strategies, namely Strategy 1 and Strategy 2, were proposed, following a regional sensitivity analysis approach, for model parameter identification. Strategy 1 aimed to identify the model parameters and the missing model input, i.e. sampling times, simultaneously, while Strategy 2 tried to separate these two processes to reduce the dimension of the identification problem through an iteration procedure. With these two strategies, the model performed well in the Qinghe WRP with the absolute relative errors between the simulated and observed total organic carbon (TOC) generally below 10%. The four model parameters were all sensitive and identifiable, and even the sampling times could be roughly identified. Given the incomplete model input, these results were encouraging and added to the trustworthiness of model when it was applied to the Qinghe WRP.

Probabilistic ecological risk assessment of effluent toxicity of a wastewater reclamation plant based on process modeling.

The growing use of reclaimed wastewater for environmental purposes such as stream flow augmentation requires comprehensive ecological risk assessment and management. This study applied a system analysis approach, regarding a wastewater reclamation plant (WRP) and its recipient water body as a whole system, and assessed the ecological risk of the recipient water body caused by the WRP effluent. Instead of specific contaminants, two toxicity indicators, i.e. genotoxicity and estrogenicity, were selected to directly measure the biological effects of all bio-available contaminants in the reclaimed wastewater, as well as characterize the ecological risk of the recipient water. A series of physically based models were developed to simulate the toxicity indicators in a WRP through a typical reclamation process, including ultrafiltration, ozonation, and chlorination. After being validated against the field monitoring data from a full-scale WRP in Beijing, the models were applied to simulate the probability distribution of effluent toxicity of the WRP through Latin Hypercube Sampling to account for the variability of influent toxicity and operation conditions. The simulated effluent toxicity was then used to derive the predicted environmental concentration (PEC) in the recipient stream, considering the variations of the toxicity and flow of the upstream inflow as well. The ratio of the PEC of each toxicity indicator to its corresponding predicted no-effect concentration was finally used for the probabilistic ecological risk assessment. Regional sensitivity analysis was also performed with the developed models to identify the critical control variables and strategies for ecological risk management.

Electrospun fibrous thin film microextraction coupled with desorption corona beam ionization-mass spectrometry for rapid analysis of antidepressants in human plasma.

Appropriate sample preparations prior to analysis can significantly enhance the sensitivity of ambient ionization techniques, especially during the enrichment or purification of analytes in the presence of complex biological matrix. Here in, we developed a rapid analysis method by the combination of thin film microextraction (TFME) and desorption corona beam ionization (DCBI) for the determination of antidepressants in human plasma. Thin films used for extraction consisted of sub-micron sized highly ordered mesoporous silica-carbon composite fibers (OMSCFs), simply prepared by electrospinning and subsequent carbonization. Typically, OMSCFs thin film was immersed into the diluted plasma for extraction of target analytes and then directly subjected to the DCBI-MS for detection. Size-exclusion effect of mesopores contributed to avoid of the protein precipitation step prior to extraction. Mass transfer was benefited from high surface-to-volume ratio which is attributed to macroporous network and ordered mesostructures. Moreover, the OMSCFs provided mixed-mode hydrophobic/ion-exchange interactions towards target analytes. Thus, the detection sensitivity was greatly improved due to effective enrichment of the target analytes and elimination of matrix interferences. After optimization of several parameters related to extraction performance, the proposed method was eventually applied for the determination of three antidepressants in human plasma. The calibration curves were plotted in the range of 5-1000 ng/mL with acceptable linearity (R(2) >0.983). The limits of detection (S/N=3) of three antidepressants were in ranges of 0.3-1 ng/mL. Reproducibility was achieved with RSD less than 17.6% and the relative recoveries were in ranges of 83.6-116.9%. Taken together, TFME-DCBI-MS method offers a powerful capacity for rapid analysis to achieve much-improved sensitivity.

New Structure Model of Au22(SR)18: Bitetrahederon Golden Kernel Enclosed by [Au6(SR)6] Au(I) Complex.

The study of atomic structure of thiolate-protected gold with decreased core size is important to explore the structural evolution from Au(I) complex to Au nanoclusters. In this work, we theoretically predicted the structure of recently synthesized four valence electron (4e) Au22(SR)18 cluster. The Au22(SR)18 cluster is proposed to possess a bitetrahedron Au7 kernel that is surrounded by a unique [Au6(SR)6] Au(I) complex and three Au3(SR)4 staple motifs. More interestingly, the Au22(SR)18 exhibits structural connections with Au24(SR)20 and Au20(SR)16. The stability of Au22(SR)18 can be understood from the superatom electronic configuration of the Au kernel as well as the formation of superatomic network. The present study can offer new insight into the structural evolution as well as electronic structure of thiolate-protected Au nanoclusters.