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Pesticides' overuse and misuse have been reported to induce ingredient variations in herbal medicine, which is now gaining attention in the medicinal field as a form of alternative medicine. To date, available studies on pesticide-induced ingredient variations of herbal medicine are limited only on a few compounds and remain most others unexamined. In this study, a plant metabolomics-based strategy was performed to systematically explore the effects of two frequently used insecticides on the comprehensive constituents of Lonicerae Japonicae Flos (LJF), the flower buds of Lonicera japonica Thunb. Field trials were designed on a cultivating plot of L. japonica with controls and treatments of imidacloprid (IMI) and compound flonicamid and acetamiprid (CFA). Unbiased metabolite profiling was conducted by ultra-high performance liquid chromatography/quadrupole-Orbitrap mass spectrometer. After data pretreatment by automatic extraction and screening, a data matrix of metabolite features was submitted for statistical analyses. Consequently, 29 metabolic markers, including chlorogenic acids, iridoids and organic acid-glucosides were obtained and characterized. The relative quantitative assay was subsequently performed to monitor their variations across flowering developments. This is the first study that systematically explored the insecticide-induced metabolite variations of LJF while taking into account the inherent variability of flowering development. The results were beneficial for holistic quality assessment of LJF and significant for guiding scientific use of pesticides in the large-scale cultivation.

Highly-efficient water splitting based on solar energy is one of the most attractive research focuses in the energy field. Searching for more candidate photocatalysts that can work under visible-light irradiation are highly demanded. Herein, using first principle calculations based on density functional theory, we predict that the two dimensional silicon chalcogenides, i.e. SiX (X=S, Se, Te) monolayers, as semiconductors with 2.43 eV~3.00 eV band gaps, exhibit favorable band edge positions for photocatalytic water splitting. The optical adsorption spectra demonstrate that the SiX monolayers have pronounced optical absorption in the visible light region. Moreover, the band gaps and band edge positions of silicon chalcogenides monolayers can be tuned by applying biaxial strain or increasing the number of layers, in order to better fit the redox potentials of water. The combined novel electronic, high carrier mobility, and optical properties render the two dimensional SiX a promising photocatalyst for water splitting., 5 figures, 2 tables

In our study, a reliable and rapid analytical method for the simultaneous determination of 15 mycotoxins (aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, alternariol, agroclavine, citrinin, diacetoxyscirpenol, deoxynivalenol, fumonisin B1, fumonisin B2, ochratoxin A, sterigmatocystin, T-2 toxin, and zearalenone) in liquorice using ultra-HPLC coupled to tandem MS was developed and validated. Due to the complex ingredients in liquorice, we chose a QuEChERS-based extraction procedure as the sample pretreatment. Meanwhile, for the first time, acetate buffer was used to replaced water, which can greatly reduce the concentration of formic acid in acetonitrile, which further reduces the extraction efficiency of impurities. The optimal combination of adsorbents is 150 mg primary secondary amine, 150 mg silica gel, 600 mg octadecylsilane, and 900 mg anhydrous magnesium sulfate. Electrospray ionization in both positive- and negative-ionization modes was applied to detect all the mycotoxins in a single run time of 15 min, with LOQs in the range of 0.125–2.5 μg/kg. The recoveries of determination obtained were in the range of 81.0–104.7%, whereas the analytes could be accurately quantified in the 0.25–625 μg/kg concentration range, with all coefficients being >0.992. Intra- and interday reproducibility were lower than 5.5 and 8.9%, respectively, for all analytical mycotoxins. The validated method was finally applied to screen mycotoxins in 31 batches of real samples collected from drugstores and hospitals in Shanghai, China. Our survey findings show that six mycotoxins were detected, including alternariol, citrinin, deoxynivalenol, fumonisin B1, ochratoxin, and zearalenone, and that the positive rate of mycotoxins was 54.8% in real samples, ranging from 3.37 to 520.6 μg/kg.

A sensitive and high-throughput method was established and validated for the simultaneous determination of 22 mycotoxins in Pheretima aspergillum (E.Perrier) and Pheretima guillelmi (Michaelsen). A modified Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method was used for sample preparation with recoveries ranging from 73% to 105% with relative standard deviations (RSDs) 0.99. In all cases, the intra- and inter-day precisions were lower than 6% and 10%, respectively. Matrix-matched calibration was utilized for quantification purposes to compensate for the matrix effects. Furthermore, the established method was successfully applied in 17 batches of normal real samples collected from different areas of China and 2 batches of moldy samples due to improper storage, only mold-contaminated samples were confirmed to have fumonisin B1 (FB1) and fumonisin B2 (FB2) contamination at 2.54-3.78μgkg-1. The constructed method could serve as a practical application of the UHPLC-MS/MS method for the trace analysis of multiple mycotoxins in complex matrixes, especially for those with high lipid contents.

To fully capture the chemo-diversity of medicinal plants is very essential for understanding of their pharmacological activities and guiding scientific quality control. Aiming to facilitate chemical characterization and novel natural products discovery, the present study proposed an integrated approach based on two-dimensional liquid chromatography coupled with quadrupole-Orbitrap mass spectrometer (2D LC/Q-Orbitrap MS). An offline comprehensive two-dimensional (2D) LC system was constructed to cover and separate multi-type constituents by combining hydrophilic interaction chromatography (HILIC) and conventional reversed phase C18. A two-step mass defect filtering-induced exclusion list-data dependent acquisition was developed to increase MS/MS coverage and selectivity. Additionally, an efficient interpretation strategy, combining an automatic matching algorithm and molecular networking (MN), was introduced for rapid recognition of known compounds and efficient elucidation of unreported ones. As a case study, the integrated approach was tentatively applied for comprehensive characterization of complex multi-type components in Lonicerae Japonicae Flos (LJF), a traditional Chinese medicine. Consequently, a total of 537 compounds were characterized from LJF, including a large number of potential novel structures. It was demonstrated that the integrated approach is powerful in deep investigation on chemical diversity of medicinal plants and discovery of novel structures. Its application could also be extended for global profiling of other complicated chemical systems, such as Chinese medicinal formulas.

Understanding the physical mechanisms that govern the ion and fluidic transport in salt-concentration-based nanochannel/nanopore systems is essential for the potential applications in bioanalysis. One central challenge is to interpret the observed four-stage change from osmosis to the reverse one with increasing salt gradient. Here we provide a unified model that outlines the intriguing role of two competing factors, the exclusion- and diffusion-induced electrical potentials. We demonstrate theoretically a direction control of a hydrodynamic flow via the salt gradient. Based on this, we also propose a salt-gradient approach for regulating DNA motion in nanochannels that enables voltage-free single-molecule capture with a significantly low translocation speed. The present method would be used as a useful protocol to overcome the key hurdle of tailoring the capture-to-translocation dynamics of polynucleotides for nanopore sequencing.

A simple, rapid, and effective method based on salting-out extraction and LC-MS/MS techniques was developed for the determination of 39 plant growth regulator (PGR) residues in two of the most common root and rhizome Chinese herbs, Codonopsis Radix (Dangshen) and Notoginseng Radix et Rhizoma (Sanqi). The extraction process was performed with acetonitrile-water (5:1) and citrate buffer extraction salt. The performance of the method was validated in accordance with the analytical quality control criteria of SANTE/11813/2017 guidelines. Analyte recoveries of 79.49–109.41% (Dangshen) and 80.17–102.81% (Sanqi) were achieved. The limit of quantifications (LOQs) were determined with the consideration of accuracy and precision. LOQs were lower than the lowest residue limits in EU pesticide regulation (10 µg/kg) for most PGRs. Moreover, the method was successfully applied in the analysis of 35 batches of Dangshen, and 60 batches of Sanqi products. The concentration of eleven PGRs were determined in analyzed samples.

A method for both qualitative screening and quantitative determination of 569 pesticides in honeysuckle was developed based on ultrahigh-performance liquid chromatography (UHPLC) coupled to quadrupole-Orbitrap high resolution mass spectrometry and an in-house executable compound database involving the theoretical masses of precursor and fragment ions and retention times. Different workflows were evaluated, validated and compared including Full MS-SIM, Full MS/ddMS2, Full MS/AIF and Full MS/DIA. For qualitative analysis, Full MS/DIA showed relatively low screening detection limits (SDLs) for most pesticides, but its MS2 identification seemed to be not reliable enough. Full MS/ddMS2 showed good repeatability of fragment ion recognition and less false positives. For quantitative analysis, the results of four workflows were comparable in terms of linearity and trueness, while Full MS-SIM and Full MS/ddMS2 gave better precision than the other two workflows for most pesticides at the spiking level of 0.01 mg/kg. Therefore, UHPLC-Full MS/ddMS2 was considered as the optimal workflow for both qualitative and quantitative analysis of honeysuckle samples. Pesticides were present in 75 of the 82 investigated samples, with concentrations ranging from 10.0 to 4116.9 μg/kg in some of the most severely contaminated samples.

In this study, a residue analysis method for the simultaneous determination of 107 pesticides in traditional Chinese medicines (TCMs), Angelica sinensis, A. dahurica, Leonurus heterophyllus Sweet, Pogostemon cablin and Lonicera japonica Thunb., was developed using gas chromatography coupled with tandem mass spectrometry in negative chemical ionisation mode (GC-NCI-MS/MS). NCI has advantages of high sensitivity and selectivity to chemicals with electron-withdrawing groups, and yields low background interference. For sample preparation, QuEChERS (quick, easy, cheap, effective, rugged and safe) was applied. Due to the unique characteristics of TCMs, the clean-up step was optimised by adjusting amounts of primary secondary amine, C18, graphitised carbon black and silica sorbents. Validation was mainly performed by determining analyte recoveries at four different spiking concentrations of 10, 50, 100 and 200 ng g(-1), with seven replicates at each concentration. Method trueness, precision, linearity of calibration curves, lowest calibrated levels (LCLs) and matrix effects were determined to demonstrate method and instrument performance. Among the 107 pesticides tested, approximately 80% gave recoveries from 80% to 110% and 10% relative standard deviation (RSD). The LCLs for nearly all pesticides were 5 ng g(-1), and as low as 0.1 ng g(-1) for dichlofenthion, endosulfan sulphate, flumetralin, isofenphos-methyl, methyl-pentachlorophenyl sulphide and trifluralin. The results indicate that GC-NCI-MS/MS is an excellent technique for quantitative and qualitative analysis of targeted GC-amenable pesticides at ultra-trace levels, especially in complex matrices such as TCMs.

A novel method for the determination of representative toxaphene congeners in traditional Chinese herbal medicines was developed. Ginseng and Milkvetch Root were selected as the samples and seven toxaphene congeners were selected as the monitoring objects. The samples were extracted by accelerated solvent extraction with cyclohexane-acetone (9:1, v/v), then cleaned-up by Florisil solid phase extraction with hexane as the eluent and the residues were detected by gas chromatography-electron ionization tandem mass spectrometry (GC-EI-MS/MS) in multiple reaction monitoring (MRM) mode. The performance was demonstrated by the analysis of Ginseng and Milkvetch Root samples spiked with toxaphene congeners at three concentration levels of 0.005, 0.01 and 0.1 mg/kg. The recoveries ranged from 72.4% to 105% with the relative standard deviations (RSDs) of 0.96%-10.4%. The limits of detection (LODs) were 0.2-1.7 microg/kg. This method is sensitive and efficient in the aspect of extraction, and can be applied to monitor the residue of toxaphene congeners in Ginseng and Milkvetch Root.

Recent experiments showed that by fabricating nanofluidic channels with hydrophobic materials, the measured amplitudes of both electroosmotic flow (EOF) and ionic current deviated significantly from the conventional electrokinetic modeling indication. Among these unexpected observations, the complicated dependence of EOF on the surface charge concentration of the channel wall remains most confusing. In this work we give a complete and unified picture for the phenomena by outlining the competing two mechanisms in the water-depletion layer around the channel wall: the decreasing trend of fluidic flow due to the redistribution of net charges, and the increasing trend because of the reduced solution viscosity there. Our quantitative evaluation illustrates that the alternate dominating by the two mechanisms leads to the observed transport behaviors. Furthermore, by considering the decreasing of ionic mobility in the depletion layer, our calculations show quantitative agreement with the latest experiments using BN nanotube channels.

With the adoption of ABAQUS/Explicit as the simulation platform, a 3D finite element model has been established to simulate the stretch bending of square tube aluminum profile which is used as the door frame of fork lifter. Four characteristic points are put forward to evaluate the distortion of cross section during deformation, and the influence to distortion of cross section from some key parameters, such as bending radius and thickness of profile, is analyzed. An orthogonal experiment is designed to evaluate the influence to deformation from other forming parameters, including preload, fill rally and filling pressure which occurred in the stretch bending process. Then neural network based response surface method and genetic algorithm are used to optimize the parameters mentioned above. Finite element simulation proved that the optimized result is valuable to reduce the distortion of cross section of profile and improve formability.

Residues of malachite green (MG), gentian violet (GV), and their leuco metabolites in channel catfish muscle were individually determined by HPLC using diode array and fluorescence detectors and confirmed by tandem mass spectrometry. This detection scheme obviates a PbO(2) reactor that converts leuco forms to chromatic forms for absorbance detection, therefore eliminating uncertainties in oxidant depletion and data integrity. Extraction was performed once in pH 3 McIlvaine buffer and acetonitrile, followed by cleanup using a polymeric strong cation-exchange column. Liquid-liquid extraction was excluded to provide an environmentally responsible and relatively rapid protocol. Spectrometric limits of detection (LOD; S/N = 3) for MG (lambda = 620 nm) and GV (lambda = 588 nm) were 0.38 and 0.26 ng/g with 44.5-49.2% and 92.2-101.4% recoveries (1-10 ng/g, n = 6), respectively. Fluorometric LOD (S/N = 3) for LMG and LGV (lambda(ex) = 266 nm, lambda(em) = 360 nm) were 0.10 and 0.09 ng/g with 74.3-84.5% and 80.6-86.5% recoveries (1-10 ng/g, n = 6), respectively. This simplified protocol saves costs and meets the sensitivity requirements set by the Food and Drug Administration and the European Union.

Particulate calcium carbonate is treated by polystyrene (PS)/polyacrylic acid (PAA) block copolymer with varied amount. Coating efficiency is obtained by measuring the dissolve curve. The results of near-infrared (NIR) analysis reveal the thickness and structural information of the surface polymer layer. The alignment of PS-b-PAA chain on and the interaction of carboxyl with the calcite surface are deduced on the basis of X-ray photoelectron spectroscopy (XPS) results.

XRD, XPS, SQUID and magnetism calculation based on spin-polarized DFT of GeTe crystalline films with different Co-doping have been studied to identify the vacancies in GeTe. The results show that Co occupies Ge vacancy and forms Co-Te bond, and confirm 8% vacancy ratio in GeTe.

A higher monitoring rate is highly desirable in the labs, but this goal is typically limited by sample throughput. In this study, we sought to assess the real-world applicability of fast, low-pressure GC-time-of-flight MS (LP-GC/TOFMS) for the identification and quantification of 150 pesticides in tomato, strawberry, potato, orange, and lettuce samples. Buffered and unbuffered versions of QuEChERS (which stands for "quick, easy, cheap, effective, rugged, and safe") using dispersive solid-phase extraction (d-SPE) and disposable pipette extraction (DPX) for clean-up were compared for sample preparation. For clean-up of all sample types, a combination of 150 mg MgSO₄, 50mg primary secondary amine (PSA), 50 mg C₁₈, and 7.5 mg graphitized carbon black (GCB) per mL extract was used. No significant differences were observed in the results between the different sample preparation versions. QuEChERS took10 min per individual sample, or1 h for two chemists to prepare 32 pre-homogenized samples, and using LP-GC/TOFMS,10 min run time and15 min cycle time allowed32 injections in 8 h. Overall,126 analytes gave recoveries (3 spiking levels) in the range of 70-120% with20% RSD. The results indicate that LP-GC/TOFMS for GC-amenable analytes matches UHPLC-MS/MS in terms of sample throughput and turnaround time for their routine, concurrent use in the analysis of a wide range of analytes in QuEChERS extracts to achieve reliable quantification and identification of pesticide residues in foods.