Search

Background and objectives : Intensive care unit (ICU) resources are inadequate for the large population in China, so it is essential for physicians to evaluate the condition of patients at admission. In this study, our objective was to construct a machine learning risk prediction model for mortality in respiratory intensive care units (RICUs). Methods: This study involved 817 patients who made 1,063 visits and who were admitted to the RICU from January 1, 2012, to December 31, 2017. Potential predictors such as demographic information, laboratory results, vital signs and clinical characteristics were considered. Among the 1,063 visits, the RICU mortality rate was 13.5%. We constructed eXtreme Gradient Boosting (XGBoost) models and compared predictive performances with random forest models, logistic regression models and clinical scores such as Acute Physiology and Chronic Health Evaluation II (APACHE II) and the sequential organ failure assessment (SOFA) system. Results : For this dataset, XGBoost models achieved the best performance with the area under the receiver operating characteristics curve (AUROC) of 0.923 (95% CI: 0.889 – 0.957) in the test set, which was significantly greater than APACHE II (0.811, 95% CI: 0.778 – 0.844) and SOFA (0.805, 95% CI: 0.770 – 0.840). The Hosmer-Lemeshow statistic was 12.667 with a P-value of 0.124, which indicated a good calibration of our predictive model in the test set. The final model contained variables that were previously known to be associated with mortality, but it also included some features absent from the clinical scores. The mean N-terminal pro-B-type natriuretic peptide (NT-proBNP) of survivors was significantly lower than that of the non-survival group (2066.43 pg/mL vs. 8232.81 pg/mL; p

In this study, a gas turbine computer integrated control system based on energy cycle optimization is designed to solve the problem of large energy loss caused by gas turbine during normal operation. At first, the circulation conditions of the internal energy of the gas turbine are analyzed through the thermodynamic structure of the gas turbine. Then, a ring structure is added to enhance the operability of the fuel supply system. Furthermore, a SCADA monitoring and control system for energy cycle are designed based on their unique system architecture. Finally, the hierarchical control principle of the system is explained from the perspective of system organization to facilitate future system development.

Herein, through a facile and energy-friendly approach, thermally stable manganese-derived amorphous stacked nanosheet (MASNS) coatings with controlled wetting property ranging from superhydrophilicity to superhydrophobicity were synthesized. The superhydrophobic MASNS coating exhibited remarkable selectivity and sensitivity in the solid phase microextraction (SPME) of non-polar aromatic analytes, even amid the abundance of polar compounds, due to the superhydrophobic effect and the stacked lamellar structures. The established method was applied to the determination of polycyclic aromatic hydrocarbons (PAHs), featuring low LODs (i.e., 0.14–0.24 ng L−1) and wide linear ranges (e.g., 10–10000 ng L−1). Extraction and desorption conditions were optimized to unleash the potential of the fiber before it was applied to the analysis of target analytes in real water samples, where satisfactory recoveries were obtained (81.7%–114.2%). This work might provide critical insights for the scalable production of superhydrophobic nanosheets as affordable and high-performance adsorbents.

Herein, an intriguing strategy is presented for preparing monolithic metal–organic framework (MOF) coatings through compactly filling up the interparticle spaces in the stacked architectures of nanocrystals. The monolithic coatings exhibited remarkably enhanced performance (double to triple compared to the MOF powders) for analyte extraction, due to the increased volumetric BET areas.

Due to the growing requirement of drug development and the increasing concern of pharmaceutical presence in the environment, bioanalysis of pharmaceuticals has raised much attention to researchers in recent years. However, the complex sample matrices and extremely low content of pharmaceuticals in biological samples are the major constraints. Therefore, great efforts have been made to overcome the subsistent difficulties in recent years, which depend mostly on sample preparation techniques. As a growing trend, developing sample preparation methodologies highlighting high throughput, automatic, on-site, non-invasive and in vivo analysis is highly recommended, which contributes greatly to both biomedical and environmental analysis. Herein, recent advances in sample preparation techniques for quantitative bioanalysis of pharmaceuticals in the past decade are reviewed and summarized, and the relative merits of each sample preparation technique are discussed. Besides, novel techniques such as electromembrane extraction and microfluidic devices are also addressed. Finally, sample preparation techniques which possess the potential for in vivo pharmaceutical analysis will be highlighted as the future trend, and prospects including miniaturization, high specificity and portability will also be discussed.

Solar-powered photocatalytic H2O2 production via simultaneous oxygen reduction and water oxidation under ambient conditions is intriguing but challenging to achieve both high oxygen reduction and water oxidation efficiencies. Herein, we report an elaborately modified carbon nitride photocatalyst presenting the highest catalytic efficiency (as high as 75 μM h-1) ever reported in ambient conditions without using any additives. The high oxygen reduction efficiency is achieved owing to the promoted adsorption and direct reduction of O2 on the defective sites of the catalyst, and the storage of electrons in redox molecules as a stable and selective medium for the relayed reduction of O2. Meanwhile, the photo-induced holes exhibit high oxidation potential (1.87 V vs NHE) capable of transforming water into H2O2 selectively, and even degrading organic pollutants as well. This work presents a potent example of producing H2O2 in a real sustainable and economical way.

Solid-phase extraction (SPE) is a popular technique for environmental sample pretreatment. However, SPE usually requires complex sample pretreatment processes, which is time-consuming and inconvenient for real-time and on-site monitoring. Herein, a solvent-free, rapid, and user-friendly SPE device was developed by coating the polydimethylsiloxane (PDMS)/divinylbenzene (DVB) sorbent on the inner wall of a sample bottle. The extraction process and desorption process were both carried out in the bottle. The analytes trapped in the sorbent were thermally desorbed and simultaneously sucked out from the bottle by an air sampling tube equipped on field-portable GC-MS. Different to previous work, the sample pretreatment process didn’t require any complicated and time-consuming steps, such as centrifugation or filtration. The total analysis time for each sample was less than 25 min, which was feasible for rapid on-site detection, and thus avoided the losses and contamination of samples in conventional sample storage and transportation processes. Under optimal conditions, the proposed SPE method exhibited wide linear ranges, low detection limits (0.010–0.036 μg L−1, which were much lower than the maximum levels restricted by the US Environmental Protection Agency and the Chinese GB3838-2002 standard), good intra-bottle repeatability (6.13–7.17%, n = 3) and satisfactory inter-bottle reproducibility (4.73–6.47%, n = 3). Finally, the method was successfully applied to the rapid detection of BTEX in the field. The recoveries of BTEX in spiked water samples ranged from 89.1% to 116.2%. This work presents a novel SPE approach for rapid on-site monitoring in water samples.

Detection of pollutants in animals and plants is crucial for understanding their capability and assessing the risk they pose to the environment and ecology. At present, the research on this area has been benefited from the advances in in vivo solid-phase microextraction (SPME), which reduces the sacrifice of animals and plants, facilitates on-site sampling and sample preparation, enables detection of unstable analytes, and facilitates long-term monitoring. This study summarizes the recent applications of in vivo SPME in detecting pollutants in animals and plants. The samplers, quantification methods, and various cutting-edge applications are discussed in detail. The future trends of using in vivo SPME in environmental analysis are also discussed.

An in vivo uptake and elimination tracing study based on solid phase microextraction (SPME) was conducted to investigate the accumulation, persistence and distribution of organochloride pesticides (OCPs) and organophosphorus pesticides (OPPs) in malabar spinach (Basella alba L.) plants. Uptake and elimination of the pesticides were traced in leaves, stems and roots of living malabar spinach plants. Root concentration factor (RCF), distribution concentration factor (DCF) and transpiration stream concentration factor (TSCF) were calculated based on the in vivo tracing data. The tracing data showed that the OCPs were much more accumulative and persistent than the OPPs in roots, while they were similarly accumulative and persistent in leaves and stems. RCF values of the OPPs or OCPs were likely to increase with the increase in LogKow values except fenthion. Obtained DCF values indicated that OPPs and OCPs were more accumulative in the organs containing more lipids. TSCF values showed that the translocation of OPPs and OCPs from roots to foliage was firstly dependent on the hydrophobicity of the compounds, but also significantly affected by the water solubility. This is the first study of generating RCF, DCF and TSCF data in living plants by in vivo sampling method, which provides a foundation to promote the application of in vivo SPME and improve understanding of contaminant behaviors in living plants.

Solid-phase microextraction (SPME) kinetics in semisolid samples should be different from that in aqueous and gaseous samples, as convection is negligible in semisolid samples but dominates mass transfer in bulk phases of aqueous and gaseous samples. This study developed a mathematical model for describing SPME kinetics in semisolid samples by considering the diffusion of analytes in two compartments, i.e., the fiber coating and the ever-increasing diffusion domain in the sample matrix. The mathematical model predicted that SPME and the desorption of preloaded analytes from the fiber would be isotropic in semisolid samples, while SPME in semisolid samples would not follow the first order kinetics as in aqueous and gaseous samples. The predictions were proven true in the experiment of four pharmaceuticals in agarose gel. In return, it was observed in the experiment that SPME kinetics would deviate more significantly from the first order kinetics for the analytes with higher partition coefficients between t...

We estimated local water storage change by combining space- and ground-based gravimetry in this paper. The gravity change from GRACE was first divided into local and global parts according to potential theory. We then subtracted the GRACE-derived global field from ground gravimeter results to obtain local gravity change which is directly induced by the local water storage. Finally we inferred the local water storage change. We used superconducting gravimeter (SG) data recorded from June 2008 to June 2012 at Wuhan station and GRACE satellite gravimetric data to estimate the local water storage change. To validate the inferred local water storage change, the water table records of a well which is several meters away from SG station were compared. Furthermore, the equivalent water heights from hydrological models and GRACE were used also for comparisons. The comparisons show that the results from combining SG and GRACE data are better than those from either GRACE data alone or hydrological models, which demonstrates the efficiency of the combination method to derive local water storage.

A novel solid-phase microextraction (SPME) fiber was prepared by gluing poly(diallyldimethylammonium chloride) (PDDA) assembled graphene oxide (GO)-coated C18 composite particles (C18@GO@PDDA) onto a quartz fiber with polyaniline (PANI). The fiber surface coating was sequentially modified with bioinspired polynorepinephrine, which provided a smooth biointerface and makes the coating suitable for in vivo sampling. The novel custom-made coating was used to extract acidic pharmaceuticals, and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was employed for analysis. The custom-made coating exhibited a much higher extraction efficiency than the previously used commercial polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings. The custom-made coating also possessed satisfactory stability (the relative standard deviations (RSDs) ranged from 1.60% to 10.3% for six sampling-desorption cycles), interfiber reproducibility (the RSDs ranged from 2.61% to 11.5%), and resistance to matrix effects. The custom-made fibers were used to monitor the presence of acid pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities (limits of detection ranged from 0.13 ng/g to 7.56 ng/g) were achieved. The accuracies were verified by the comparison with liquid extraction. Moreover, the novel fibers were successfully used to monitor the presence of acidic pharmaceuticals in living fish, which demonstrated that the custom-made fibers were feasible for possible long-term in vivo continuous pharmaceutical monitoring.

In vivo solid-phase microextraction (SPME) sampling method coupled with gas chromatography-mass spectrometry (GC-MS) analysis was employed to trace the uptake and elimination of organophosphorus pesticides (OPPs) in two kinds of edible plants, cabbage (Brassica parachinensis) and aloe (Barbadensis). The metabolism of fenthion in aloe was also investigated by the liquid chromatography tandem mass spectrometry analysis (LC-MS/MS) to understand the fate of OPPs in living plants better. Transpiration stream concentration factor (TSCF) and depuration rate constants of the OPPs in living plants were obtained therein. The health risk of the OPPs treated aloe was estimated by the maximum residue limit (MRL) approach, and it revealed that the OPPs were rather safe for their fast degradable property. However, peak concentration of fenthion-sulfoxide was found to exceed the MRL and was higher than that of the parent fenthion, which indicated the potential risk of pesticide metabolites. This study highlighted the application of in vivo SPME for contaminant tracing in different living edible plants. The in vivo tracing method is very convenient and can provide more data to evaluate the risk of different pesticides, which are very important for the safety of agriculture production.

Headspace solid-phase microextraction (HS-SPME) of low volatile analytes from complex aqueous samples can be substantially facilitated by elevating the temperature of the samples. However, many SPME coatings prepared from novel sorptive materials may suffer from low stabilities in hot water steam. Herein, a superhydrophobic metal-organic framework (MOF) derived from decorating the metal-oxo nodes of the amino-functionalized UiO-66(Zr) with phenylsilane was prepared and successfully developed into a novel SPME fiber coating. The highest extraction efficiencies towards the semi-volatile ultraviolet (UV) filters were achieved when the aqueous samples were heated up to 100 °C. It was notable that the lab-made coating exhibited extraordinary stability towards hot water steam, probably because the hydrophobic groups capped on the MOF prevented water molecules from entering and deconstructing its lattice. Even after being treated with water steam under 100 °C for 21 h, the extraction performance of the coating remained unchanged, and the crystal structure of the MOF maintained. Furthermore, a negligible matrix effect was observed even in the samples containing humic acid. Under the optimal extraction and thermal desorption conditions, a method for determining UV filters in aqueous samples was established, which possessed low detection limits (0.6–2.1 ng L−1), wide linear ranges (10–50000 ng L−1), good inter-fiber reproducibility (2.3–6.0%, n = 6), and satisfying intra-fiber repeatability (1.8–5.8%, n = 3). The method was successfully applied in quantifying UV filters in environmental water samples. In addition, the lab-made NH2-UiO-66(Zr)-shp-coated fiber was also suitable for the analysis of polycyclic aromatic hydrocarbons (PAHs). This study provided an effective strategy for preparing MOF coatings that can maintain their crystalline structures and high extraction performances in high-temperature steam.

Immunosuppression is currently a vital pathophysiological characteristic and core problem of sepsis. Apoptosis of T lymphocyte contribute to immunosuppression by decreasing immune effector cells. A report has recently revealed the potential regulatory role of exosomal miRNAs derived from plasma of septic patients on immune system, but the underlying mechanism is unclear. We discovered the antiapoptotic effect of circulating exosomes derived from plasma of septic patients (Sepsis-Exos) on T lymphocytes and further investigated the molecular mechanism. Next-generation sequencing (NGS) indicated that sepsis induces prominent change of exosomal miRNA expression profile, including the overexpressed hsa-miR-7-5p. Gene Bad, which is in the cGMP-PKG signaling pathway, was negatively regulated by hsa-miR-7-5p by dual luciferase reporter assay. Sepsis-Exos were demonstrated to downregulate the mRNA and protein levels of proapoptotic gene Bad, active Caspase-3 and Bax, while upregulate that of antiapoptotic gene Bcl-2 via hsa-miR-7-5p, thus inhibited apoptosis of T lymphocytes induced by lipopolysaccharide (LPS) in vitro. Furthermore, Sepsis-Exos was verified to inhibit T lymphocytes apoptosis during sepsis in vivo, reducing mortality rate of septic model mice. In conclusion, we provide evidence that Sepsis-Exos participate in ameliorating apoptosis of T lymphocytes by directly suppressing Bad via hsa-miR-7-5p.

Encapsulating functional nanomaterials within the bulk of metal-organic frameworks (MOFs) offers the opportunity to construct high-performance hybrid coating materials for solid phase microextraction (SPME). In this work, we proposed the facile synthesis of a superhydrophobic MOF composite material (NSZIF-8Si) by growing ZIF-8 on MnxOy nanosheet (NS) and subsequently depositing short-chain polysiloxane on the surface of the composite. A novel SPME fiber was successfully prepared based on the NSZIF-8Si composite. The NSZIF-8Si fiber possessed outstanding thermal stability (up to 450 °C). In headspace SPME of BTEX, the home-made fiber exhibited extraction efficiencies much higher than the commercially available PDMS fiber. This phenomenon was due to the synergetic cooperation of the π-π stacking and the hydrophobic interactions between the NSZIF-8Si coating and the analyte molecules, as well as the increased aspect ratio of the MOF grown on the nanosheet. The established method achieved wide linearity (5–2000 ng L−1) and low LODs (0.02 ng L−1 to 0.21 ng L−1). Satisfactory recoveries were obtained in the analysis of real water samples collected from the Pearl River, indicative of the good reliability of the established method for real-scenario applications. This work might provide critical insights in constructing novel NS/MOF composite materials for the development of high-performance SPME fiber coatings.

BACKGROUND Sepsis is a life-threatening disease that is an immune disorder response that causes multiple organ dysfunction. In this study, we investigated the dynamic changes in mRNA expression of HLA-DRA gene and the specific transcription factor of helper T cell subsets to explore long-term immunophenotyping and its relationship with prognosis. METHODS Seventy-eight sepsis patients and twelve healthy controls were recruited in this study. Blood samples were collected at eight-time points during their septic course and were assayed for the gene expression of HLA-DRA and T helper cell subset-specific transcription factors (T-bet: Th1, GATA3: Th2, Foxp3: Treg, RORC: Th17). RESULTS The levels of HLA-DRA in survivors gradually increased but were maintained at lower levels in non-survivors. The specific transcription factor of Th1 and Th2 cells, T-bet and GATA-3 were significantly lower in sepsis patients than in normal controls, and the non-survivors showed significantly lower levels than the survivors (P

A novel, low-cost and effective in-needle solid-phase microextraction device was developed for the enrichment of trace polycyclic aromatic hydrocarbons in water samples. The in-needle solid-phase microextraction device could be easily assembled by inserting hydrofluoric acid-etched wires, which were used as adsorbent, into a 22-gauge needle tube within spring supporters. Compared with the commercial solid-phase microextraction fiber, the developed device has higher efficiency for the extraction of polycyclic aromatic hydrocarbons with four to six rings from water samples using the optimized extraction conditions. With gas chromatography equipped with a flame ionization detector, the limits of detection for the polycyclic aromatic hydrocarbons with four to six rings ranged from 0.0020 to 0.0067 ng/mL. The relative standard deviations for one needle and needle-to-needle extractions were in the range of 5.2-9.9% (n = 5) and 3.4-12.3% (n = 5), respectively. The spiked recoveries of the polycyclic aromatic hydrocarbons in tap water samples ranged from 73.2 to 95.4%. This in-needle solid-phase microextraction device could be a good field sampler because of the low sample loss over a long storage time.

Analysis of organic pollutants is usually accomplished in centralized laboratories. However, the time-delayed and time-consuming process is insufficient and risky for precisely detection due to the contamination of vials, the losses of analytes during transportation and storage. Herein, a rapid and highly sensitive on-site detection approach was developed without using any vials by coupling an on-site pre-equilibrium solid phase microextraction (SPME) sampling method with a portable gas chromatography mass spectrometer (portable GC-MS), for the determination of three families of persistent organic pollutants (polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons). Based on sampling-rate (SR) calibration method, the concentrations of target analytes in aquatic systems could be easily determined. Limits of detection (LODs) in the low parts-per-tillion levels (≤5.25 ng·L−1) were obtained for most of the investigated analytes with a total analysis time only ∼30 min. The proposed on-site detection approach was then successfully applied in the determination of persistent organic pollutants in real aquatic environment. A comparable result obtained by liquid extraction (LE) equipped with laboratorial GC-MS demonstrated the accuracy of the on-site detection method. In general, this study demonstrated a rapid and highly sensitive on-site approach, avoiding any risks of contamination during sampling and analysis, for determination of POPs as well as the potential applications for other organic pollutants in aquatic phase.

Antibiotics are a group of antibacterial drugs used in the treatment and prevention of bacterial diseases in humans, veterinary animals, and farmed fish. Inappropriate and excessive use of antibiotic therapy leads to antibiotic fragment in the water bodies thus affect the aquatic organisms. In this study, an amino group modified high surface area metal-organic framework (MOF) MIL-101(Cr)-NH

Miniaturized sample pretreatment platforms have simplified analytical tasks in diverse disciplines. Herein, a novel pipet microextraction (PME) device is reported by making use of the photothermal property of a light-heatable sorbent (LHS) for the first time. Efficient and staining-free heating treatment of small volumes of liquids confined in the PME device is now enabled through light illumination. The light-induced heating treatment is capable of dramatically accelerating solvent elution rates, effectively unlocking bound toxin from its antibody, and rapidly quenching enzymatic activities, thus, provides PME with higher efficiencies and enables its new applications in antibody-intermediated sampling of targeted toxin from stained food surfaces and powders, as well as in accurate revelation of enzymatic reaction kinetics. This study offers a new perspective of designing efficient and versatile microextraction platforms and demonstrates their potential applications in different fields including public security, new drug development, and environmental protection.

Carbohydrates are known to be involved in a wide range of biological and pathological processes. However, due to the presence of multiple hydroxyl groups, carbohydrate recognition is a particular challenge. Herein, we reported an ultrasensitive solid-phase microextraction (SPME) probe based on phenylboronic acid (PBA) functionalized carbon nanotubes (CNTs) for direct in vitro or in vivo recognition of carbohydrates in biofluids as well as semi-solid biotissues. The coating of the proposed probe possessed a 3D interconnected porous architecture formed by the stacking of CNTs. As a result, the binding capacity toward carbohydrates was excellent. The proposed approach was demonstrated to be much superior to most carbohydrate sensors, including higher sensitivity, wider linear range, and excellent qualitative ability in multi-carbohydrate systems. Thus, this approach opens up new avenues for the facile and efficient recognition of carbohydrates for important applications such as glycomics.

The presence of complex matrix in the aquatic system affects the environmental behavior of hydrophobic organic compounds (HOCs). In the current study, an automated solid-phase microextraction (SPME) desorption method was employed to study the effect of 2-hydroxypropyl-β-cyclodextrin (β-HPCD) on the kinetic process of 5 selected polyaromatic hydrocarbons (PAHs) desorbing from the fiber in aqueous sample. The results showed that the added β-HPCD facilitated the desorption rates of PAHs from SPME fiber coating, and the enhancement effect can be predicted by a proposed theoretical model. Based on this model, the kinetic parameters of organic compounds desorbing from the SPME fiber can be determined, and the calculated results showed good agreement with the experimental data. In addition, the effect of temperature on the desorption kinetic was investigated. The results found that the SPME desorption time constant increased as the sampling temperature elevated, and followed the Arrhenius equation. Also, the temperature facilitated the desorption of HOCs from the bound matrix so that increased the lability degrees of the bound compounds. Finally, a calibration method based on the proposed theoretical model was developed and applied for the analysis of unknown sample.

Solid phase microextraction (SPME) has become a useful tool for in vivo monitoring the behavior of environmental organic pollutants in biological species due to its simplicity, relatively non-invasive, and cost-effective manner. However, the complex matrices in biological samples could significantly influence the extraction kinetic, and bias the quantification result. In this study, we investigated the effect of complex matrix on the extraction kinetic of SPME for biological sample analysis. Two sample matrices, phosphate-buffered saline (PBS) with bovine serum albumin (BSA) and agarose gel with BSA were used to simulate the biological fluid and tissue. Results showed that the addition of BSA significantly enhanced the mass transfer of organic compounds onto SPME fiber in both PBS buffer and gel sample. Enhancement factors ranging from 1.3 to 27, and 2.0 to 80 were found for all selected polyaromatic hydrocarbons (PAHs) in PBS buffer and agarose gel with BSA concentration of 0.1-5%, respectively. Then, an improved theoretical model was applied to quantify the observed enhancement effect, and the result showed that the predicted sampling time constant agreed well with the experimental one in complex matrix. Furthermore, a simplified equation was proposed for the real biological sample analysis.

In recent years, great concerns have been raised about salicylic acid (SA) and its derivatives as plant regulators. Therefore, precise determination of the distribution of SAs in the living plants is necessary for not only fundamental researches but also the regulating mechanisms. In this study, a custom-made solid phase microextraction (SPME) fiber based on diallyl dimethyl ammonium chloride-assembled graphene oxide-coated C18 composite (C18@GO@PDDA) was proposed for in vivo detection of salicylic acid, acetylsalicylic acid (ASA), 4-methyl salicylic acid（4-SA）and 3-methyl salicylic acid (3-SA) in aloe plants. Under the optimized conditions, the analytical performance evaluated in homogenized aloe plant tissues exhibited low detection limits (1.8–2.8 μg g−1), wide linear ranges (10–5000 μg g−1), and satisfactory reproducibility (relative standard deviations less than 8.4% and 9.3% for inter-fiber and intra-fiber assays, respectively). Under cadmium stress, the developed method was applied for the in vivo tracing of four salicylic acids in aloe plants. A 48-h in vivo tracing revealed that salicylic acids were involved in the pathway of cadmium stress tolerance. To our best knowledge, it is the first effort to realize the in vivo analysis of SA and its derivatives in plants, and it has a made a great step forward in the area of plant hormone analysis.

In this study, electrospun nanofibers were used as solid-phase microextraction (SPME) fiber coatings after substituting the water-soluble sheath of the emulsion electrospun polystyrene (PS)@Plurinic F-127 core-sheath nanofibers with biocompatible and water-stable polydopamine (PDA) and subsequently being appropriately cross-linked with glutaraldehyde (GA) to enhance the strength of the electrospun architecture. The novel custom-made PS@PDA-GA coating was wettable in aqueous solutions and thus exhibited much higher extraction efficiency than the nonsheathed PS nanofiber coating and the thicker polydimethylsiloxane (PDMS) coating. The novel coating also possessed excellent stability (relative standard deviations (RSDs) less than 7.3% for six sampling-desorption cycles), interfiber reproducibility (RSDs less than 14.3%), and antibiofouling ability, which were beneficial for in vivo sampling. The PS@PDA-GA fiber was used to monitor pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities with the limits of detection in the range of 1.1 (mefenamic acid) to 8.9 (fluoxetine) ng·g(-1) and comparable accuracies to liquid extraction were achieved. In general, this study explored a convenient and effective method to sheath nanofibers for high-efficient in vivo SPME of analytes of interest in semisolid tissues.

Here we report the successful utilization of the stepwise ligand exchange strategy for the improvement of adsorption ability of a series of bio-MOFs. The fast extraction rate and the different adsorption performances of the three bio-MOF coatings were dominated by their pore structures.

Solid-phase microextraction (SPME) coupled with liquid chromatograph (LC) is widely used to detect polar and ionic organic compounds, including various pharmaceuticals and endogenous bioactive compounds. In this study, a small-sized insert tube for use in the commercial autosampler vial was designed for eluting the extracted analytes from SPME fibers for LC analysis. By using this custom-made insert tube as an alternative to the commercial insert tube, the volume of the elution solvent was reduced by four-fifths. Even though smaller fractions of the analytes were eluted from the fiber coatings, the analyte concentrations in the elution solutions were substantially increased by using the custom-made insert tube. Therefore, larger amounts of the analytes could be injected to LC and higher signal-to-noise ratios could be achieved, even at smaller injection volumes. Since the elution in the custom-made insert tube was nonexhaustive, four strategies were developed to figure out the extracted amounts in the fiber coatings. In combination with the sampling-rate calibration method, these strategies were successfully used to determine the concentrations of fluoxetine in living tilapias. This study provides a simple but effect way for improving the analytical sensitivity when coupling SPME with LC.

Magnetic molecularly imprinted polymers (MMIPs) have superior advantages in sample pretreatment because of their high selectivity for target analytes and the fast and easy isolation from samples. To meet the demand of both good magnetic property and good extraction performance, MMIPs with various structures, from traditional core-shell structures to novel composite structures with a larger specific surface area and more accessible binding sites, are fabricated by different preparation technologies. Moreover, as the molecularly imprinted polymer (MIP) layers determine the affinity, selectivity, and saturated adsorption amount of MMIPs, the development and innovation of the MIP layer are attracting attention and are reviewed here. Many studies that used MMIPs as sorbents in dispersive solid-phase extraction of complex samples, including environmental, food, and biofluid samples, are summarized. Graphical abstract The application of magnetic molecularly imprinted polymers (MIPs) in the sample preparation procedure improves the analytical performances for complex samples. MITs molecular imprinting technologies.

Sensitivity and selectivity of the solid phase microextraction (SPME) in analysis are mostly determined by the coating material of the fiber used. Graphene oxide (GO) has attracted great attention because of its large specific surface area, rich oxygen functional groups, good dispersibility in aqueous solution and high reactivity. However, the low thermal stability of the functional groups limits the wide application of GO in SPME coating design. Highly cross-linked polyoxyethylene (POE) is a substrate widely used for composite material construction, which could significantly improve the thermal stability, water resistance as well as biocompatibility of the functional materials. In this study, we incorporated GO with highly cross-linked POE as a novel fiber coating material for SPME through the gluing approach. The obtained fiber possessed a wrinkled shape surface, which could increase the accessible surface area. In addition, the thermal and chemical stability of the fiber coating were also improved, rendering the fiber rigid enough for more than 100 repetitive extraction cycles. The performance of this developed SPME method for phenols was evaluated by headspace extraction of phenols in aqueous samples. Compared with three commercial fibers, the home-made fiber showed excellent extraction efficiencies towards phenols. Under the optimized conditions, it showed low detection limits (0.12–1.36 ng· L−1), good precision ( 99%), as well as good enrichment efficiencies (enrichment factors (EFs), 172–1752). Furthermore, the method was successfully applied in simultaneous analyses of five phenols for real water samples with satisfactory recoveries (81–113% for the Pearl River samples).

Fluoroquinolones (FQs) are a group of antimicrobial agents that have been widely used for therapeutic purposes in clinical medicine for human and veterinary diseases, as well as in aquaculture production. Their residues, however, may survive in foods of animal origin, thus causing health risks for human. In this study, a rapid and sensitive method based on in vivo solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to detect the residues of five FQs in cultured puffer fish (Takifugu obscurus). In vitro fiber evaluation experiment demonstrated that, compared with the thicker polydimethylsiloxane (PDMS) coating (165µm), the custom-made biocompatible C18-PAN fibers (45µm) exhibited much higher extraction efficiencies towards FQs (approximately 9-31 times). The custom-made C18-PAN coating also possessed excellent reproducibility in fish muscle with the intra-fiber relative standard deviations (RSDs) ranging from 11.2% to 14.3% (n = 6) and inter-fiber RSDs ranging from 13.1% to 16.1% (n = 6), which was suitable for in vivo sampling. The custom-made SPME fibers were subsequently applied to determine fluoroquinolones in dorsal-epaxial muscle of living puffer fish. The accuracies were verified through the comparison with traditional liquid extraction (LE) method, and the sensitivities were demonstrated to be satisfying with the limits of detection (LODs) ranging from 0.3ngg-1 to 1.5ngg-1. In general, this study presented a convenient and high-efficient method to determine fluoroquinolones in puffer fish by in vivo sampling.

For the purpose of obtaining a more comprehensive flavor profile, volatile compounds in traditional Chinese dry-cured hams were studied by dual-fiber solid-phase microextraction (SPME) using two fibers simultaneously. By using the selected pair of fibers and under the optimal extraction time, there were total seventy-two volatile compounds identified, which was higher than the mono-fiber SPME method using a single fiber. Out of the seventy-two compounds, twenty-six compounds were not detected by using mono-fiber SPME and five among them are classified as the major aromatic compounds in the literatures. Due to the higher coverage and less tendency for the occurrence of competition among the volatiles, the total amount of volatiles extracted by dual-fiber SPME (510.02 ng/kg) was higher than mono-fiber SPME. Three grades of dry-cured hams were successfully distinguished based on dual-fiber SPME. The volatile compounds belonged to nine chemical families and differed in different grades of dry-cured hams. These results show that dual-fiber SPME is capable of analyzing flavor profiles more comprehensively and distinguishing traditional Chinese dry-cured hams.

We developed a new approach for computing the changes in the length of day (LOD) due to earthquakes from both shear- and tensile-type faults. This approach was based on the point dislocation theory for a SNREI Earth, which was validated by comparing our results with the ones obtained by the normal mode method. We defined two numerical functions that vary with hypocenter depth. These functions allow us to compute the co-seismic change of the trace of the Earth's inertia tensor, and hence the co-seismic LOD change. For future applications, by adding a trace term, we corrected Lambeck's formulas ( Lambeck, 1980 ), which are being commonly used for computing co-seismic LOD change. Finally, the new approach was used to compute the co-seismic LOD change from 1977 to 2011. The results show that the co-seismic trace and the co-seismic J2 changes contribute to the LOD change with the same magnitude ( Gross and Chao, 2006 ). This means that, unlike other deformation mechanisms, the trace term cannot be neglected when modeling the co-seismic LOD change. The earthquakes from 1977 to 2011 decreased the LOD by about 12 μs, and the rate of decrease was enhanced after the 2004 Sumatra earthquake due to several large earthquakes.

In recent years, pharmaceuticals have received increasing attentions because of their potential risks to the environment, but researches focusing on their impacts on defense system of living plants are still lacking. As an important class of phytohormones, jasmonates play crucial roles in plant defense system against environmental stress. In order to investigate the effect of pharmaceuticals uptake on endogenous jasmonates, an in vivo solid phase microextraction (SPME) method was established to simultaneously detect and monitor both pharmaceuticals and jasmonates in living plants. The proposed method exhibited wide linear ranges, high sensitivity (limits of detection ranging 0.0043–0.035 ng g−1 for pharmaceuticals and 0.091–0.22 ng g−1 for jasmonates, respectively), and satisfactory reproducibility (relative standard deviation of intrafiber ranging 4.2%–8.6% and interfiber ranging 5.2%–8.2%, respectively). Subsequently, this method was successfully applied to track the concentrations of each pharmaceutical and corresponding jasmonates in living Malabar spinach plants (Basella alba. L) exposed to three common pharmaceuticals (i.e. gemfibrozil, mefenamic acid and tolfenamic acid) over 15 days. In result, all pharmaceuticals appeared to trigger intensive biosynthesis of jasmonic acid (JA) (3.1–9.4 times of control) while reduced the concentration of methyl jasmonate (MeJA) (18.3%–38.1% of control). We inferred that uptake of pharmaceuticals acted as an abiotic stress and stimulated the plant defense response because of the variation of jasmonates. To the best of our knowledge, this is the first study applying SPME to detect and track both pharmaceuticals and phytohormones in living plants, which not only provided a glimpse to the adverse effect of pharmaceuticals on plants as well as the regulation of endogenous jasmonates, but also set a promising template for future in vivo analysis of xenobiotics and plant endogenous substances.

Recent developments of solid-phase microextraction (SPME) in biological and environmental analysis calls for robust and low-cost fibers that are prone to batch preparation with good reproducibility. However, the expensive commercial fibers and low reproducible home-made fibers cannot fully cater these requirements. In the present study, an extremely low-cost (less than one dollar) SPME fiber with good intra-fiber (RSDs% ≤ 1.6%, n = 6) and inter-fiber reproducibility (RSDs% ≤ 6.2%, n = 6) was prepared by mounting a piece of commercially available polydimethylsiloxane (PDMS) tubing on a stainless steel wire with epoxy glue. This configuration was stable for more than 100 extraction/thermal desorption cycles. In addition, compared with previously used thicker PDMS fiber, the capability of direct thermal desorption in gas chromatograph of the present fiber not only simplified the sample preparation process but also enhanced the analysis sensitivity. Excellent inter-fiber reproducibility and low cost even made the fiber disposable when used in complex matrices.

An attempt has been made to search for the translational oscillations of the Earth’s solid inner core in the gravity measurements recorded with the superconducting gravimeters (SG) from the worldwide network of the Global Geodynamics Project (GGP). All the SG data were prepared and analyzed by the same method to remove accurately the signatures related to gravity tides, local barometric pressure, the Earth’s rotation, the long-term trend and so on. We obtained the estimations of the power spectral densities of each residual series and the estimations of the product spectral densities in the subtidal band (0.162–0.285 cph) were obtained by using a multi-station stacking technique after further eliminating atmospheric effects. The inner core translation triplet was detected in the subtidal band. We find 6 groups of signal with high signal-to-noise ratio that are consistent with the characteristics of the triplet, and 4 groups of the results that are close to the previous studies and the differences are less than 0.92%. It implies that the groups of signatures all have the possibility to be related to the inner core translational oscillations.

a b s t r a c t Gravity effect due to ocean tide loading (OTL) is an important signal and correction in various gravimetric applications. In this paper, we assessed the OTL gravity effects at four absolute gravity (AG) stations in coastal China from several perspectives. The integrated Green's function of the Newtonian part was derived analytically and that of the elastic part was computed based on the PREM earth model. Ocean tide (OT) records near the four AG stations were used to enhance the accuracy of the global ocean tide model of NAO99b and the regional model of NAO99jb for the innermost field (

We review the new and most commonly used coating materials for solid-phase microextraction (SPME) in the past five years. We discuss ionic liquids (ILs), polymeric ILs, graphene, carbon nanotubes, molecularly imprinted polymers and metal-organic frameworks, based on the recent trends in SPME-fiber coatings. The designable basic structures indicate the possibilities for developing more task-specific SPME fibers using these materials.

Density functional theory (DFT) calculations were used to explore the hydrolysis mechanism of the DNA analog BNPP (BNPP= bis(4-nitrophenyl)phosphate) catalyzed by the mononuclear zinc(II):OH- complex of 1,5,9-triazacyclododecane (Zn:([12] aneN(3))). We present a binding mode in which one terminal phosphoryl oxygen atom as well as the nucleophilic group (hydroxyl anion) binds to zinc center. Two potential mechanisms were found as follows: one is a concerted mechanism with a reaction barrier of 18.1 kcal/mol in liquid phase of implicit solvent and 13.8 kcal/mol in liquid phase of explicit solvent of water molecules; the other is a stepwise mechanism with a hydroxylated phosphate reaction intermediate of a quasi-trigonal bipyramid configuration but is less feasible. Both the concerted reaction pathway and stepwise reaction pathway are S(N)2 manner of nucleophilic substitution reactions. Meanwhile polar protic solvents like water, methanol and ethanol are favored in the catalyst-assisted hydrolysis mechanism. We explore the rationality of deprotonation of mono-anionic phosphates in the transient products and find that it is difficult to dissociate a proton and the ultimate product is NPP- rather than NPP2-. These results are consistent with and systematically interpret the experimental observations, more importantly, provide useful suggestions in the catalyst design and solvent selection. (C) 2012 Elsevier B.V. All rights reserved.

New formulas for computing coseismic polar motion excitation and low-degree gravity changes, not only for shear but also for tensile earthquake, based on point dislocation theory are presented, with a set of concise expressions of Stokes coefficients in terms of dislocation Love numbers and fault parameters. The formulas directly involve an arbitrary seismic source and coseismic deformation and are validated through numerical computation for some specific earthquakes by comparison with previous results obtained using a normal mode approach. As an application, the formulas are applied to compute coseismic polar motion excitation and low-degree gravity changes caused by the 2011 Tohoku-Oki earthquake (Mw9.0). Numerical results show that the coseismic J 2 change reaches magnitudes of between 10 −14 and 10 −13 , and coseismic J 3 , J 4 , and J 5 changes appear at a magnitude of 10 −12 . Furthermore, the polar motion excitation and J 3 and J 4 changes are explicitly dependent on the slip magnitude of the sub-fault whereas J 2 and J 5 are explicitly dependent on the horizontal location of the sub-fault. In addition, the generalized figure axis should have shifted by about 4 mas (milliarcseconds) toward 132°E longitude.

Ever since its invention, solid phase microextraction (SPME) has been widely used for aqueous sampling. In recent years, this technique has received increasing attention for the analysis of complex water sample because of its capability of sensing freely dissolved analytes in the complex matrix. In this chapter, the development of negligible depletion SPME (nd-SPME) for the determination of freely dissolved analytes in complex water samples is reviewed. The fundamentals and sampling conditions of nd-SPME are first discussed. Then, the application of nd-SPME for measurement of sorption coefficients in complex matrixes is summarized. In addition, the calibration methods of nd-SPME are discussed in detail, especially the effect of complex matrix on the sampling kinetic. For the first time, the advances of complex matrix effects including retarded and enhanced effects on the SPME sampling kinetic are fully explored.

The basic principles for the preparation of SPME fibers with satisfying selectivity, sensitivity, loading capacities and stabilities are summarized here in terms of the physicochemical properties of the coating materials and the supporting substrates of SPME fibers. While the main part of this chapter focuses on the advances in developing the most widely used coating materials, including ionic liquids, polymeric ionic liquids, carbonaceous materials, molecularly imprinted polymers, metal-organic frameworks, metals and metal oxides, conductive polymers, modified silica, as well as their composites, into SPME fibers. Meanwhile, the applications of novel SPME fibers in analyzing diverse analytes in different sample matrices are briefly reviewed, including the emerging applications of SPME in the extraction of bioactive compounds in living animals and plants.

A biocompatible probe for specific glucose recognition is based on photoinitiated boronate affinity-molecular imprinted polymers (BA-MIPs). The unique pre-self-assembly between glucose and boronic acids creates glucose-specific memory cavities in the BA-MIPs coating. As a result, the binding constant toward glucose was enhanced by three orders of magnitude. The BA-MIPs probe was applied to glucose determination in serum and urine and implanted into plant tissues for low-destructive and long-term in vivo continuous glucose monitoring.