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For the first time, a PEC immunosensor based on a signal amplification strategy is successfully constructed to quantitatively detect alpha-fetoprotein in serum sample. Three favorable factors explain the ultra-high sensitivity of this method. Firstly, compared with pure BiPO

With the rapid development of green chemistry, the design and application of the related methods and requisite solvents have received increasing attention in recent years. Deep eutectic solvents (DESs) are mixtures formed from a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD). Generally, ionic liquids (ILs) and DESs have similar physical and chemical properties, and hence, find application in the same fields. However, DESs have many advantages over ILs, such as non-toxicity, environmental friendliness, low cost, and biodegradability. Thus, there are many areas where DESs play a key role and act as new, efficient green extraction solvents. DESs can aid the extraction and separation of different target compounds from a variety of samples, thus promoting the rapid development of sample pretreatment technology. As extraction solvents, DESs offer unique advantages. In dispersive liquid-liquid microextraction (DLLME), DESs show incredible ability to extract residual drugs, metal ions, and bioactive components from complex matrices, which would require complicated sample preparation steps when using traditional organic extraction solvents. Compared with traditional organic extraction solvents, DESs have considerable merits of greenness, hypotoxicity, higher extraction efficiency, etc. Moreover, as a dispersant, a DES can accelerate the diffusion of the extractant in the sample solution during DLLME, owing to its benefits of miniaturization and low cost. Traditional dispersants such as methanol and acetonitrile have many disadvantages, including high volatility, flammability, and toxicity, while DESs are environmentally friendly. Therefore, the combination of DES and DLLME has recently gained prominence in the field of sample preparation. Additionally, the combination of DES and solid-phase extraction (SPE) has broad application prospects. By virtue of their diverse functions, DESs have been used as eluents, in combination with a solid-phase extraction column and a stir bar, to elute analytes from the sorbent surface. The molar ratio of the HBA and HBD is one of the important factors influencing the elution efficiency. DESs can be combined with magnetic multiwalled carbon nanotubes, magnetic graphene oxide, and other nanocomposites to specifically adsorb target analytes through hydrogen bonding, π-π forces, and electrostatic forces. In addition, the DES can be used in the synthesis of magnetic nanocomposites and molecularly imprinted polymers when combined with magnetic materials. Magnetic nanocomposites functionalized with DES show excellent performance and high efficiency in the extraction process. The combination of DES and magnetic materials would promote the development of magnetic materials for green chemistry and expand the application of DES to several other fields. However, to the best of our knowledge, research on the microstructure, physical and chemical properties, and extraction mechanism of DESs is still in its nascent stage. Therefore, exploring the theoretical mechanism and applications of new DESs with special functions would be an essential future research direction. This article integrates the research progress of DESs in extraction separation technology; introduces the preparation, properties, and classification of DESs; and summarizes the applications of DESs in DLLME and SPE.

An efficient and environmentally friendly ultrasound-assisted (UAE) natural deep eutectic solvent (NADES) extraction method was applied for the extraction of five bioactive compounds (liquiritin, isoliquiritin, liquiritigenin, glycyrrhizic acid and isoliquiritigenin) from compound liquorice tablets (CPLTs), and the antioxidant activities of these compounds were evaluated. In this study, eighteen different NADES systems based on either two or three components were tested and a 1,4-butanediol–levulinic acid system (1 : 3 molar ratio) was selected as a topgallant solvent for maximizing analyte extraction yields. Various extraction parameters, such as water content, liquid/solid ratio, extraction time and temperature, were systematically optimized by single-factor and response surface methodology (RSM) experiments. The results indicated that the optimum extraction conditions for the analytes featured a water content of 17%, a liquid/solid ratio of 42 mL g−1 and an extraction time of 30 min. The extracted amounts of liquiritin, isoliquiritin, liquiritigenin, glycyrrhizic acid and isoliquiritigenin reached 5.60, 3.17, 1.27, 74.62 and 1.34 mg g−1, respectively, under optimized conditions, which were much higher than those extracted using conventional organic solvents. In addition, antioxidant tests revealed that the NADES extracts showed higher DPPH and hydroxyl radical-scavenging capacity than the conventional solvent extracts used for comparison. This study provides a suitable approach for efficiently extracting the bioactive compounds of CPLTs. Meanwhile, NADESs can be extended to other natural products as green extraction media.

A novel dual-emission ratiometric fluorescent probe based on N-doped yellow fluorescent carbon dots (y-CDs) and blue fluorescent copper nanoclusters (CuNCs) was established for quantitative determination of Cu2+ and biothiols. In this work, the Cu2+-(y-CDs) complexes formed by the chelation of y-CDs with Cu2+, showed an absorption peak at 430 nm that not only enhanced the fluorescence of y-CDs through inhibiting photoinduced electron transfer (PET) but also effectively quenched the fluorescence of CuNCs due to Forster resonance energy transfer (FRET). In addition, the chelation of y-CDs with Cu2+ could be inhibited by biothiols that prevented the fluorescence of y-CDs from being enhanced and the fluorescence of CuNCs from being quenched. On account of the changes of ratiometric signal, a dual-emission fluorescence probe for Cu2+ and biothiols determination was achieved. The proposed method exhibited high sensitivity for Cu2+ and biothiols in the ranges of 0.5–100 μM and 0.8–50 μM and the limits of detection (LODs) of Cu2+, glutathione (GSH), cysteine (Cys) and homocysteine (Hcy) were 0.21 μM, 0.33 μM, 0.39 μM and 0.46 μM, respectively. Subsequently, the established strategy presented an application prospect for the detection of Cu2+ and biothiols in real samples.

A simple, inexpensive, reliable and environmentally friendly method based on vortex-assisted dispersive liquid-liquid microextraction combined with solidification of a floating organic drop (VA-DLLME-SFO) followed by high performance liquid chromatography with a diode array detector (HPLC-DAD) was developed to determine benzoic acid (BA) and sorbic acid (SA) in ketchup and powder bags of instant noodles. Hydrophobic natural deep eutectic solvents (NADESs), as the microextraction solvent, were prepared with ternary components. Acetic acid can reduce the viscosity of hydrophobic NADESs and vortex can promote the dispersion of NADESs in aqueous solvents. In the DLLME process, several key parameters were optimized, including the type and volume of hydrophobic NADES, pH value, vortex time and salt content. Meanwhile, these parameters were assessed using response surface methodology based on the Box-Behnken design (BBD). Under optimal conditions, the developed method showed good linearity in the selected range (r2, 0.9997). The limits of detection were 0.2 μg mL-1 and 0.07 μg mL-1 for BA and SA, respectively. Recoveries were in the range of 82.21% to 102.70% and the relative standard deviations (intra-day and inter-day precisions) were less than 5.66%. The proposed method was successful in analyzing BA and SA in ketchup and powder bags of instant noodles.

A target-dependent ratiometric fluorescence sensing strategy was designed and fabricated based on a redox reaction for highly sensitive detection of α-glucosidase (α-Glu) activity and its inhibitor. In this study, silicon quantum dots (SiQDs) with excellent optical properties and two-dimensional (2D) cobalt oxyhydroxide (CoOOH) nanosheets were successfully prepared and exploited for the detection of analytes. The CoOOH nanosheets are able to oxidize o-phenylenediamine (OPD), and the product 2,3-diaminophenazine (oxOPD) not only quenches the blue fluorescence of SiQDs (440 nm) by the inner filter effect (IFE) but also emits orange fluorescence (565 nm). α-Glu can catalytically hydrolyze l-ascorbic acid-2-O-α-d-glucopyranosyl (AA2G) to produce ascorbic acid (AA). The redox between AA and CoOOH could lead to the damage of CoOOH nanosheets, thereby inhibiting the oxidization of OPD and effectively preserving the fluorescence of SiQDs. Thus, ratiometric detection of α-Glu activity was achieved according to the AA-dependent dual-fluorescence signal responses. Under the optimal conditions, good linearity was obtained in the range of 0.01-6 U mL-1 with a detection limit of 0.004 U mL-1. The IC50 of α-Glu inhibitor acarbose was estimated to be 0.216 μM. The method provides high sensitivity and selectivity for the determination of α-Glu activity and its inhibitor, which has great application potential in clinical diagnosis and anti-diabetic drug screening. Furthermore, a logic gate analytical device was successfully established based on double fluorescence signals, which makes it possible to monitor α-Glu activity by intelligence equipment.

Herein, we report a novel sensor to detect trypsin using a purpose-designed fluorescein-labelled peptide with negatively charged carbon nanoparticles (CNPs) modified by acid oxidation. The fluorescence of the fluorescein-labelled peptide was quenched by CNPs. The sensor reacted with trypsin to cleave the peptide, resulting in the release of the dye moiety and a substantial increase in fluorescence intensity, which was dose- and time-dependent, and trypsin could be quantified accordingly. Correspondingly, the biosensor has led to the development of a convenient and efficient fluorescent method to measure trypsin activity, with a detection limit of 0.7 μg/mL. The method allows rapid determination of trypsin activity in the normal and acute pancreatitis range, suitable for point-of-care testing. Furthermore, the applicability of the method has been demonstrated by detecting trypsin in spiked urine samples., Graphical abstract Image 1, Highlights • Compared with other quenchers, CNPs was proved to be effective in quenching the fluorescence intensity of 99.2%. • The fluorescent FRET biosensor exhibited high selectivity and sensitivity. • This assay we investigated was cost-effective and convenient. • This method is applied to detect trypsin in urine with satisfactory recoveries.

Introduction The Epimedium herb, Yinyanghuo in Chinese, is a famous Chinese herbal medicine. In this study, an efficient extraction method was developed for the extraction of major bioactive constituent epimedin A, epimedin B, epimedin C and icariin from E. pubescens Maxim. using deep eutectic solvents (DESs). Methodology A series of choline chloride-based DESs were synthesised for the extraction of four target compounds. DES composed of lactic acid and choline chloride with the ratio of 2:1 was selected as the most promising. Three vital factors affecting the extraction yields including water content, volume of DES aqueous solution and extraction time were optimised systematically by Box-Behnken experimental design in combination with response surface methodology. A high-performance liquid chromatography ultraviolet (HPLC-UV) method was developed for the sensitive and accurate quantification. Results The optimal extraction conditions were obtained as follows: water content of 17.5% (v/v), volume of DES aqueous solution 3.14 ml, and extraction time of 21 min. Under the optimal extraction conditions, the developed DES method could supply almost the same extraction yield as 50% ethanol, which were 98%, 99%, 97%, 96% for epimedin A, epimedin B, epimedin C and icariin, respectively. Conclusion The present study exhibited high efficiency in extraction of prenylflavonol glycosides in E. pubescens Maxim. Thus, DESs could be used as an alternative for efficient extraction and quantification of biologically active components from natural medical plants.

A photoelectrochemical (PEC) immunosensor based on MIL-101(Cr) and CdTe-QDs composites (MC) was successfully synthesized to assay the carcinoembryonic antigen (CEA) in human serum and urine samples. This novel method contained three key aspects: 1), the polarity of the photocurrent based on MIL-101(Cr) itself could be altered by applying a different voltage to detect the cathode and anode photocurrent. 2), the introduction of cadmium telluride quantum dots (CdTe-QDs) greatly improved the efficiency of light utilization. 3), the photogenerated electron-hole-pairs were suppressed and their separation efficiency was improved by effective matching of energy level between MIL-101(Cr) and CdTe-QDs. Due to the inherent insulating properties of the biological matrix, the transfer of photogenerated electrons was hindered, leading to a decreased photocurrent signal. Under the optimal condition, the anodic and cathodic detection limit of the PEC immunosensor for CEA was 0.00018 ng mL

A pH-dependent red fluorescent N, P co-doped carbon dots (N, P-CDs) was firstly developed for rapid, sensitive and visual detection of the toxic dye malachite green (MG). The synthesis of N, P-CDs was carried out by hydrothermal treatment of o-phenylenediamine and phosphoric acid, and the low cytotoxicity of N, P-CDs was verified by Cell Counting Kit-8 (CCK-8) method. The linear decrease of N, P-CDs fluorescence in the pH range of 3.8-5.6 was attributed to the reduction of protonation of nitrogen-containing groups on the surface. And the sensing mechanism for MG was constructed based on the inner filter effect (IFE). The obtained linear ranges were 0.08-1 and 1-50 µmol·L

Nitrite is a widely used food additive that has been shown to be carcinogenic and can cause health damage when consumed in excess. Therefore, developing a detection method is in demand. Here, we prepared a novel Fe-doped carbon dots (Fe-CDs) using metallic deep eutectic solvent (MDES) which showed high sensitivity and selectivity. Besides, it also showed excellent pH-dependent luminescence characteristics, which proved the feasibility as a pH sensor. Under the optimal conditions, the detection linear of nitrite ranged from 0.2 to 80 µM, and the detection limit was 50 nM. The recovery rate was between 98.8 % and 104.1 % in food and water samples. For pH monitoring, its fluorescence intensity was linearly correlated in the pH range from 2 to 7, accompanying a unique differential solution color change of colorless-yellow-green. Therefore, it can be used as an excellent fluorescent probe for detection of nitrite and pH in food and water environment.

Curcumin and its two derivatives of PB-3 and DY-1 were subjected to the forced degradation studies under the conditions of hydrolysis (acidic and alkaline), oxidation, photolysis, and thermal stress recommended by ICH Q1A (R2) by means of UPLC–DAD–MS/MS. Three analytes and their degradation products were separated on a column of ACQUITY UPLC® BEH C18 (100 mm × 2.1 mm, 1.7 μm) with an in-line filter prior to the column using acetonitrile and 10 mM ammonium acetate buffer (pH adjusted to 3.5) as a mobile phase. Both curcumin and DY-1 showed extensive degradation under alkaline condition and gave rise to two degradation products for curcumin and three for DY-1, respectively, while no degradation product was observed under other tested conditions. PB-3 was found to be unstable in acid and alkaline conditions, two degradation products in acidic hydrolytic condition and one in alkaline condition were obtained, while it was stable in photolytic, oxidative and thermal stress conditions. The degradation products of three analytes were characterized as follows by analyzing the mass fragmentation patterns of curcumin and mass analysis of the degradation products: ferulic acid and vanillin for curcumin, 3-methoxyl-4-[3-(1-tetrahydropyrrolyl)propoxyl] benzoic aldehyde, 2,2-di-(1-phenylmethyl)-3-oxo-5-[3-methoxyl-4-(3-tetrahydropyrolylpropoxyl)] pent-4-enoic acid, and tetrapyrolyl propoxyl methoxyl phenyl prop-2-enoic acid for PB-3, 3-oxo-5-[4-hydroxyl-5-methoxyl-3-(1-morpholinylmethyl)] pent-4-enoic aldehyde, 3-oxo-5-(4-hydroxyl-5-methoxyl-3-(1-morpholinylmethyl)) pent-4-enoic acid and 2-hydroxyl-3-methoxyl-5-(7-(3-methoxyl-4-hydroxylphenyl)-3,5-dioxo-4,4-dimethyl hept-1,6-dienyl) benzoic acid for DY-1, respectively. The degradation pathways of curcumin and its derivatives were presented in addition. Keywords: Curcumin, PB-3, DY-1, UPLC–DAD–MS/MS, Degradation products

The incidence of drug-induced liver injury (DILI) is second only to viral hepatitis and steatohepatitis in China, and DILI has become a serious public health problem that cannot be ignored. Guri Gumu-13 pill (GRGM) is a traditional Chinese medicine (TCM), which has a protective effect on liver diseases. However, the underlying therapeutic mechanisms of GRGM for DILI are still vague. In this study, the protective effect of GRGM on acetaminophen (APAP)-induced DILI was investigated based on the proteomics clues. The effects of GRGM on APAP-induced DILI in rats were studied using tandem mass tag (TMT)-based quantitative proteomics technology. Besides, western blotting was exerted to verify related proteins. Using the TMT-based quantitative proteomics approach, 237 proteins were identified as regulated in APAP-induced DILI and 58 proteins were regulated by GRGM. The 17 overlapping differentially expressed proteins (DEPs) were identified, and 7 proteins were inversely regulated. Enrichment analysis of KEGG indicated that metabolic pathways, linoleic acid metabolism, and retinol metabolism might be affected in DILI. Next, Cyp2c11, Aldh1a1, and Fads2 were verified with molecular biotechnology. GRGM exerts therapeutic effects through multi-pathways regulation in the treatment of DILI. This work may provide proteomics clues for the continuation of research on DILI treatment with GRGM.

It plays an important role to effective detection of amphenicols antibiotic residues in food and an important issue considering of possible impact on human health. In this work, the molecularly imprinted membranes (MIMs) were proposed to simultaneously recognize and detect thiamphenicol (TAP), florfenicol (FF) and chloramphenicol (CAP) in pork and milk samples. The synergistic effect of graphene oxide (GO), double functional monomer (methacrylate and acrylamide) and "click chemistry" strategy prompted the membranes to possess good surface hydrophilicity (48.6°), excellent selectivity and capacity to exclude macromolecules. The theoretical models of selectivity mechanism showed the selective recognition depended mainly on the hydrogen bond interaction and van der Waals interaction between the analytes and monomers. The limit of detection for 3 analytes were 0.04-0.28 µg kg

An efficient analysis platform composed of nanozyme-based hydrogel kit and smartphone was constructed for on-site detection of uric acid (UA) in a rapid and realiable manner. CuCo

A novel fluorescent probe based on a nitrogen-doped carbon dot (N-CD) and CdTe quantum dot (CdTe QD) platform has been constructed for H2O2/glucose detection and pH sensing. In this work, H2O2-tolerant blue fluorescence N-CDs were added to the H2O2-mediated yellow fluorescence quenching of CdTe QDs to construct a dual-color ratiometric fluorescent H2O2 probe. H2O2-induced passivated group detachment and action on deep nanocrystals promoted CdTe QD fluorescence quenching. Meanwhile, the addition of the blue fluorescent background of N-CDs sharply reflected the color change in CdTe QDs. Under the optimized experimental conditions, the platform was effectively applied to the detection of H2O2 produced by the enzymatic reaction of glucose, showing high sensitivity (limit of detection 7.86 μM) and wide linear range (26-900 μM) for glucose detection. The pH-sensing behavior of CdTe QDs and N-CDs was attributed to the displacement of a weak acid (3-mercaptopropionic acid) by a strong acid (HCl) and the acid titration process of two coexisting bases (N-CDs and NH3·H2O), respectively. The loss of passivation and doping effects led to a decrease in the fluorescence intensity of CdTe QDs and N-CDs. Moreover, utilizing the ability of bimaterial system fluorescence to pH sensing, a semiquantitative pH detection based on the linear response was developed. The pH range was analyzed by three kinds of N-CD (Fex = 440 nm) and CdTe QD (Fex = 548 nm) typical emission spectral shapes. In addition, the recovery results showed that the bimaterial system was proved to be appropriate for the assay of glucose in spiked serum samples.

Dopamine (DBA) as an important biomarker, plays a crucial role in disease diagnosis. In this study, we have developed a fast and simple aptamer-based fluorescence strategy which used single-wall carbon nanohorns (SWCNHs) as a quencher for dopamine detection. SWCNHs were negatively charged after pretreated, which improved its dispersion in solution. 5-carboxy-fluorescein (FAM) was used to label dopamine aptamer. In the absence of dopamine, FAM-modified aptamer could be absorbed onto the SWCNHs surface due to π-π interaction, resulting in the fluorescence intensity decreased. Dopamine could specifically bind with FAM-DNA to form G-quadruplex, which could not be absorbed onto the surface of SWCNHs. Hence, the fluorescence of FAM-DNA recovered, and the fluorescent intensity as a function of different concentrations of dopamine was measured. We obtained a detection limit of 5 μM for this detection system with a linear detection range of 0.02-2.20 mM. Furthermore, the feasibility of the innovative detection system has been verified by detecting dopamine in spiked serum samples.

An ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) combined with magnetic solid-phase extraction (MSPE) was developed for extraction of quinolones (quinolones) from honey and milk prior to high-performance liquid chromatography (HPLC) analysis. 1-Butyl-3-methylimidazolium hexafluorophosphate was used as the extraction solvent and an effective adsorbent based on chitosan modified magnetic core-shell functionalized multi-walled carbon nanotube (MWCNTs-Fe3O4@SiO2-CS) nanoparticles was used to assist IL to adsorb quinolone residues in honey and milk samples. Extraction conditions were optimized through one-factor-at-a-time and response surface methodology using a Box-Behnken design. Under optimum conditions satisfactory linearity (R2 > 0.999) and high sensitivity (method limits of quantification were 4-8 μg kg-1 or μg L-1 in honey or milk samples) was achieved. The recoveries of quinolones in honey and milk ranged from 81.2 to 109%. Based on this study, the proposed method was employed for the determination of antibiotic residues in honey and milk samples.

A novel dual-emission ratiometric fluorescent probe based on N-doped yellow fluorescent carbon dots (y-CDs) and blue fluorescent copper nanoclusters (CuNCs) was established for quantitative determination of Cu

A simple, quick, effective turn-on fluorescence assay for the determination of fipronil (FIP) was built based on the yellow fluorescence of FAM-aptamer and excellent quenching capability of the oxidized single-walled carbon nanohorns (The oxidized SWCNHs). Oxidized SWCNHs with the great advantage of good dispersibility in solution were generated by link to carboxyl group and were added to a specific FAM-aptamer at an optimal concentration to form an “on–off” oxidized SWCNH/FAM-aptamer fluorescent sensor. The structures of the oxidized SWCNHs were verified, and the comprehensive properties were evaluated by characterization techniques. This paper has exploited oxidized SWCNHs as a quenching agent to detect fipronil for the first time. Under the optimized conditions, the limit of detection (LOD) for fipronil was 3 nM, and the recovery of fipronil varied from 88.6% to 112.7% in different real samples with relative standard deviations (RSDs) not more than 5%. The developed method could be successfully applied for the determination of fipronil in tap water, honey and corn samples.

With the rapid development of green chemistry, the design and application of the related methods and requisite solvents have received increasing attention in recent years. Deep eutectic solvents (DESs) are mixtures formed from a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD). Generally, ionic liquids (ILs) and DESs have similar physical and chemical properties, and hence, find application in the same fields. However, DESs have many advantages over ILs, such as non-toxicity, environmental friendliness, low cost, and biodegradability. Thus, there are many areas where DESs play a key role and act as new, efficient green extraction solvents. DESs can aid the extraction and separation of different target compounds from a variety of samples, thus promoting the rapid development of sample pretreatment technology. As extraction solvents, DESs offer unique advantages. In dispersive liquid-liquid microextraction (DLLME), DESs show incredible ability to extract residual drugs, metal ions, and bioactive components from complex matrices, which would require complicated sample preparation steps when using traditional organic extraction solvents. Compared with traditional organic extraction solvents, DESs have considerable merits of greenness, hypotoxicity, higher extraction efficiency, etc. Moreover, as a dispersant, a DES can accelerate the diffusion of the extractant in the sample solution during DLLME, owing to its benefits of miniaturization and low cost. Traditional dispersants such as methanol and acetonitrile have many disadvantages, including high volatility, flammability, and toxicity, while DESs are environmentally friendly. Therefore, the combination of DES and DLLME has recently gained prominence in the field of sample preparation. Additionally, the combination of DES and solid-phase extraction (SPE) has broad application prospects. By virtue of their diverse functions, DESs have been used as eluents, in combination with a solid-phase extraction column and a stir bar, to elute analytes from the sorbent surface. The molar ratio of the HBA and HBD is one of the important factors influencing the elution efficiency. DESs can be combined with magnetic multiwalled carbon nanotubes, magnetic graphene oxide, and other nanocomposites to specifically adsorb target analytes through hydrogen bonding

Surface roughness and slope gradient are two important factors influencing soil erosion. The objective of this study was to investigate the interaction of surface roughness and slope gradient in controlling soil loss from sloping farmland due to water erosion on the Loess Plateau, China. Following the surface features of sloping farmland in the plateau region, we manually prepared rough surfaces using four tillage practices (contour drilling, artificial digging, manual hoeing, and contour plowing), with a smooth surface as the control measure. Five slope gradients (3°, 5°, 10°, 15°, and 20°) and two rainfall intensities (60 and 90 mm/hr) were considered in the artificial rainfall simulation experiment. The results showed that the runoff volume and sediment yield increased with increasing slope gradient under the same tillage treatment. At gentle slope gradients (e.g., 3° and 5°), the increase in surface roughness prevented the runoff and sediment production, that is, the surface roughness reduced the positive effect of slope gradient on the runoff volume and sediment yield to a certain extent. At steep slope gradients, however, the enhancing effect of slope gradient on soil erosion gradually increased and surpassed the reduction effect of surface roughness. This study reveals the existence of a critical slope gradient that influences the interaction of surface roughness and slope gradient in controlling soil erosion on sloping farmland. If the slope gradient is equal to or less than the critical value, an increase in surface roughness would decrease soil erosion. Otherwise, the increase in surface roughness would be ineffective for preventing soil erosion. The critical slope gradient would be smaller under higher rainfall intensity. These findings are helpful for us to understand the process of soil erosion and relevant for supporting soil and water conservation in the Loess Plateau region of China.

Reservoir tillage (RT) improves the soil rainwater harvesting capacity and reduces soil erosion on cropland, but there is some debate regarding its effectiveness. The objective of this study was to further verify the effect of RT on soil erosion and explore the reasons for this effect by analysing microrelief changes during rainfall. Rainfall intensities of 60, 90, and 120 mm/hr and three slope degrees (5, 15, and 25°, representing gentle, medium, and steep slopes) were considered. A smooth surface (SS) served as the control. The microrelief changes were determined based on digital elevation models, which were measured using a laser scanner with a 2‐cm grid before and after rainfall events. The results showed that compared with the values for the SS, RT reduced both the runoff and sediment by approximately 10‐20% on the gentle slope; on the medium slope, although RT also reduced the runoff in the 90‐ and 120‐mm/hr intensity rainfall events, the sediment increased by 158.90% and 246.08%; on the steep slope, the sediment increased by 92.33 to 296.47%. Overall, when the runoff control benefit of RT was lower than 5%, there was no sediment control benefit. RT was effective at controlling soil loss on the gentle slopes but was not effective on the medium and steep slopes. This is because the surface depressions created by RT were filled in with sediment that eroded from the upslopes, and the surface microrelief became smoother, which then caused greater soil and water loss than that on an SS at the later rainfall stage.

Leaf litter is an important component of agroforestry ecosystems that plays a key role in soil and water conservation. This study assessed the effect of leaf shape on water interception under controlled laboratory conditions. Two contrasting leaf shapes (needle-leaf, represented by Pinus massoniana; and broad-leaf, represented by Magnolia grandiflora) were placed in a steel box (2 m long and 1 m wide) for separate experiments with different leaf masses per ground area (0.5, 1.0 and 1.5 kg/m2); the steel box was positioned on two different slopes (5° and 20°) corresponding to gentle and steep slopes; the rainfall intensity was 90 mm/h. The results indicated that leaf shapes had specific effects on the interception storage capacity of the leaf litter on a slope. The needle-leaf litter intercepted 2.08 times more rainwater than the broad-leaf litter on average. As the leaf mass increased, the interception storage capacity of the leaf litter successively increased for the needle-leaf litter, while there were no obvious patterns for the broad-leaf litter. This difference occurred because the initially erect broad leaves were easily flattened by raindrop impacts due to their large surface areas and hence formed a horizontal leaf cover (or leaf overlap). This leaf accumulation structure restricted the infiltration of rainwater into the lower leaf litter while providing a short path for rainwater to leave the leaf litter, hence promoting litter flow and leading to less rainwater intercepted by the broad-leaf litter than the needle-leaf litter. Our results provide a better understanding of the effects of leaf shape on leaf litter interception on inclined slopes, which is lacking in the current literature.

Palbociclib (named PD 0332991) is a novel highly selective cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitor, which has been approved by the Food and Drug Administration (FDA) for the treatment of hormone-receptor-positive advanced breast cancer. This present study developed a comprehensive strategy to investigate the metabolic profile of palbociclib in rat urine, feces and bile samples based on an ultra high performance liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (UHPLC-FT-ICR MS). A total of 29 metabolites, including 18 phase I metabolites and 11 phase II metabolites, were detected and identified. The metabolic pathways included hydroxylation, oxidation, dehydrogenation, N-dealkylation, carbonylation, oxidative deamination, acetylation, glucuronidation, sulphate conjugation as well as the crossover of multiple metabolic pathways in vivo, and 16 of these metabolites were proposed for the first time. This study showed an insight into the metabolism of palbociclib in vivo, which may provide relevant chemical information for subsequent studies in the future.

A simple, rapid, and sensitive gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the simultaneous determination of two fatty acids, methyl hexadecanoate (MH) and methyl stearate (MS), to allow the evaluation of packaging-drug compatibility. The two migrants were quantified in selective ion-monitoring (SIM) mode, with limits of detection (LOD) of 0.0030 μg/mL and 0.0121 μg/mL. Linear calibration curves for MH and MS were obtained in the concentration ranges of 0.1011–5.0570 μg/mL and 0.2015–10.0740 μg/mL, respectively. The developed method was successfully applied to estimate the safety of the injection of recombinant antitumor-antivirus protein (RAAP). The results showed that the possible maximum daily intake was 3.0 ng and 12.1 ng for MH and MS, respectively. As these values were both below the permitted daily exposure, the migrants can be considered as having low safety risk and do not affect the quality of the injection. Keywords: Compatibility, Rubber stoppers, Injection, Fatty acids, GC-MS

Soil rainwater harvesting (SRWH) is an important process in rainfed farming areas. Improving the capacity for SRWH via tillage is essential in many parts of the world. In recent years, reservoir tillage (RT) has attracted attention because it was said that RT contributes to SRWH. The objectives of this study were to measure the cumulative soil-harvested rainwater (SHR) of slopes subjected to RT and to evaluate the contribution of RT to SRWH under different rainfall conditions. A smooth surface (SS) served as a control surface. Three slope degrees (5°, 15° and 25°) were subjected to low and heavy (60 and 120 mm/h) and long-term rainfall (90 min). The results showed that the cumulative SHR decreased to different extents under different rainfall intensities as the slope degree increased. On the gentle slope (5°) and under low rainfall intensity (60 mm/h), no significant differences in cumulative SHR were detected between the RT and SS treatments, whereas significant differences in cumulative SHR were detected between them on the steep slopes (15° and 25°) and under high rainfall intensity (120 mm/h). The differences in cumulative SHR among the different conditions occurred because the contribution of RT to SRWH varied as the soil surface properties changed (especially as surface depression storage decreased due to sediment deposition) under the conditions of long-term rainfall. For example, on the 5° slope at a rainfall intensity of 120 mm/h, the contribution of RT to SRWH was 18.58% during the 0-30-min rainfall stage but -14.84% during the 60–90-min stage, resulting in nearly equal cumulative SHR values between the RT slope and the SS slope. Our results suggest that RT is not necessary contribute to SRWH in all cases.

This paper presents a novel multi-residue method for the enantioselective analysis of 22 chiral pesticides in cucumber, tomato, cabbage, grape, mulberry, apple and pear at enantiomeric levels. Pesticides were efficiently extracted by magnetic solid-phase extraction based on graphene as sorbent. Response surface methodology was used to assist the multivariable optimization. The perfect chiral separation of the enantiomers was achieved on a Chiralpak IG column within 47 min by reversed-phase liquid chromatography coupled with tandem mass spectrometry, which is a significant improvement to resolve a large group of chiral compounds under one set of conditions. The method was validated in terms of selectivity, linearity, sensitivity, trueness and precision, which all satisfy the requirement for pesticides residue analysis. The proposed method was successfully applied for monitoring the occurrence and enantiomeric composition of pesticides in different fruits and vegetables, demonstrating its applicability for the routine analysis of chiral pesticide residues in food samples.

Guizhi Fuling capsule (GFC) was an important traditional Chinese herbal medicine used for the treatment of primary dysmenorrheal (PD). The aim of this study was to evaluate the anti-dysmenorrheal effect of GFC on dysmenorrheal rats induced by oxytocin and to investigate its mechanism of action. An integrative urinary metabolomic study based on 1H NMR and UPLC-MS was used to investigate the therapeutic effect of GFC on PD rats. In addition, in order to obtain more potential biomarkers and to investigate the global urine metabolic profile associated with PD, we combined the characteristics of RP-UPLC-MS with HILIC-UPLC-MS on metabolomic platform to find non-polar and polar metabolites. Finally, a total of 36 potential biomarkers were identified as being primarily involved in the TCA cycle, gluconeogenesis, glycolysis, pentose phosphate pathway, lipid metabolism, energy metabolism, amino acid metabolism and intestinal flora metabolism, and PD could influence the balance of many of these metabolic pathways in vivo. Furthermore, these results also suggested that the GFC had therapeutic effects on PD rats via the regulation of multiple metabolic pathways. In conclusion, the variations in potential biomarkers revealed the therapeutic mechanism of GFC, and these potential biomarkers were both significant for early diagnosis and predicting PD.

A variety of green deep eutectic solvents (DESs) combined with ultrasound-assisted extraction (UAE) were successfully investigated and applied in simultaneous extraction of five bioactive flavonoids in Radix scutellariae. In this paper, 12 DESs were initially screened, then the effective extraction of scutellarin, baicalin, wogonoside, baicalein and wogonin was achieved by using tailor-made DES composed of L-proline and glycerol at a 1 : 4 molar ratio. Experimental design was performed by response surface methodology (RSM) based on a central composite design (CCD). 50 mg of sample powder was extracted by sonication for 42 min with 1.20 mL of aqueous solution containing 66.7% (v/v) DES, resulting in the optimum extraction efficiency. The recoveries of the five main bioactive flavonoids in Radix scutellariae were in the range of 97.1–100.7% (RSDs were below 2.9%). This established method provided good linearity, precision and accuracy. As a result, the contents of scutellarin, baicalin, wogonoside, baicalein and wogonin in Radix scutellariae (20 170 910) were 74.05 ± 1.89 mg g−1, 176.3 ± 3.06 mg g−1, 35.96 ± 0.38 mg g−1, 1.76 ± 0.04 mg g−1 and 0.60 ± 0.02 mg g−1, respectively. The content of baicalin extracted using the Chinese Pharmacopeia (2015) method was 151.3 ± 2.54 mg g−1. In comparison using the Student's t-test (p > 0.05), there was no significant difference between the Chinese Pharmacopeia (2015) method and our established method. This work indicates that DESs are promising as green and efficient solvents for analysis of various samples from plant herbs.