Distinct DNA conformations during forward and backward translocations through a conical nanopore.

DNA conformations, which encompass the three-dimensional structures of the DNA strand, play a crucial role in genome regulation. During DNA translocation in a nanopore, various conformations occur due to interactions among force fields, the fluidic environment, and polymer features. The most common conformation is folding, where DNA moves through the nanopore in a two-strand or multi-strand manner, influencing the current signature. Factors such as hydrodynamic drag, ionic environments, and DNA length significantly affect these conformations. Notably, conical nanopores, with their asymmetrical geometry, impose unique constraints on DNA translocation. Our findings reveal that during forward translocation, from the narrow (cis) end to the wide (trans) end, DNA experiences less resistance, resulting in shorter translocation times and higher blockade currents. Conversely, backward translocation, from the wide (trans) end to the narrow (cis) end, leads to longer translocation times and more complex conformations due to increased hydrodynamic drag and geometric constraints. This study employs molecular ping-pong methods to confine DNA, further highlighting the intricate dynamics of DNA folding within nanopores. These insights enhance the understanding of DNA behavior in confined environments, contributing to advancements in nanopore-based sensing and sequencing technologies, with implications for genome regulation and biomedical applications.

Strategies, techniques and applications for food authentication based on carbohydrates: A review.

The increasing complexity and ubiquity of food processing and the emergence of fraudulent practices have made effective and reliable methods to authenticate food products of utmost importance. Carbohydrates, with various nutritional functions, are abundant in foods and can serve as potential markers for food authentication. However, the complex and diverse structures and properties of carbohydrates, especially polysaccharides, pose challenges. Nonetheless, significant progress has been made in this area. This paper provides an overview of the utilization of carbohydrates in food authentication since 2000, focusing on strategies involving carbohydrate-based markers, carbohydrate profiles, and carbohydrate-protein interaction-based assays. The analytical techniques, applications, challenges and limitations of these strategies are reviewed and discussed. The findings demonstrate that these strategies offer origin verification, quality assessment, adulteration detection, process control, and food species identification. Notably, oligosaccharide analysis has proven effective in food authentication and remains a promising marker, especially for analyzing intricate matrices. The advances in chromatography separation and mass spectrometry identification of isomers and trace amounts of these compounds have facilitated the discovery of such markers. In conclusion, carbohydrate analysis can play a crucial role in food authentication. Future research and development will make the authentication of carbohydrate-rich foods ever more accurate and efficient.

Obinutuzumab in Refractory Membranous Nephropathy: A Case Series.

Rationale & Objective: Membranous nephropathy (MN), recognized as an autoimmune kidney disease, responds well to anti-CD20 monoclonal antibodies. Obinutuzumab, a type Ⅱ humanized anti-CD20 and immunoglobulin G1 Fc-optimized monoclonal antibody, when compared with rituximab, has demonstrated superior efficacy in B-cell leukemia and lymphoma, especially in rituximab-resistant cases. However, the efficacy and safety of obinutuzumab in MN remain unclear. Study Design: A case series study. Setting & Participants: A total of 18 patients were diagnosed with MN and had received obinutuzumab at our center without secondary MN, undergoing dialysis, having a history of kidney transplantation, or infections requiring treatment. Exposure: Obinutuzumab treatment. Outcomes: Primary outcomes included remission rate, time to first remission, and first relapse-free survival time during the follow-up period. Analytical Approach: Survival analysis was performed with Cox proportional hazards models, log-rank test, and Kaplan-Meier survival analysis. Results: Patients with MN (median age of 52.5 years, 83.3% males) received an average dose of 2.1 ± 0.8 g of obinutuzumab during a median follow-up period of 13.6 months. During the follow-up, 17 patients (94.4%) achieved remission, with 12 patients (66.7%) achieving partial remission, and 5 patients (27.8%) achieving complete remission. The median time to first remission and first relapse-free survival time was 2.7 (1.0-6.1) months and 9.8 (2.6-11.2) months, respectively. Of 12 patients with previous rituximab treatment, all achieved remission successfully, with 8 (66.7%) achieving partial remission and 4 (33.3%) achieving complete remission. Adverse events were mostly mild, and no severe treatment-related adverse events were observed. Limitations: Limited or missing data; risks of selection bias; or recall bias; underestimated first relapse-free survival time because of a limited follow-up period; unmonitored counts of CD19+ B-cells and other lymphocyte subsets. Conclusions: Obinutuzumab demonstrated promising efficacy and safety in inducing remission in MN, particularly in patients with an unsatisfactory response to rituximab.

Membranous nephropathy (MN), an autoimmune kidney disease, usually responds favorably to rituximab, a chimeric anti-CD20 monoclonal antibody. Nevertheless, certain patients exhibit inadequate responses to rituximab. Obinutuzumab, a novel humanized anti-CD20 monoclonal antibody, has shown enhanced efficacy in cases where rituximab fails to address B-cell leukemias and lymphomas. However, its efficacy and safety in MN treatment remain uncertain. A case series involving 18 patients treated with obinutuzumab at our center demonstrated promising results, suggesting favorable efficacy and safety in inducing and maintaining remission, particularly among patients who did not respond well to rituximab previously. These findings signify a potential alternative for MN treatment, though further research is needed to confirm them.

Factors predicting complications following open reduction and internal fixation of intra-articular distal radius fracture.

Objective: This study aimed to determine the incidence and predictors of the complications after open reduction and internal fixation (ORIF) of intra-articular distal radius fracture (IADRF) with a minimum follow-up of 12 months. Methods: Medical records and outpatient follow-up records were retrospectively reviewed to collect medical, surgical, and complication data on consecutive patients who had undergone an ORIF procedure for an IADRF between January 2019 and June 2022. Data included demographics, comorbidities, injury, surgical characteristics, and laboratory findings on admission. A multivariate logistic regression model was constructed to identify the significant predictors, with a composite of any complications occurring within 12 months after the operation as the outcome variable and potentially a range of clinical data as the independent variables. The magnitude of the relationship was indicated by the odds ratio (OR) and the 95% confidence interval (CI). Results: During the study period, 474 patients were included, and 64 had documented complications (n = 73), representing an accumulated rate of 13.5%. Among them, carpal tunnel syndrome was the most common, followed by tenosynovitis caused by tendon irritation/rupture, superficial or deep wound infection, complex regional pain syndrome (CRPS) type 1, radial shortening (≥4 mm), plate/screw problems, and others. The multivariate results showed the following factors significantly associated with increased risk of complications: experience of DRF surgery with <30 cases (OR: 2.2, 95% CI: 1.6-3.5), AO type C fracture (OR: 1.7, 95% CI: 1.2-2.9), initial lunate facet collapse of ≥5 mm (OR: 4.2, 95% CI: 1.4-8.9), and use of temporary external fixation before index surgery (OR: 2.4, 95% CI: 1.5-4.3). Conclusions: These findings may aid in patient counseling and quality improvement initiatives, and IADRF should be directed by an experienced surgeon.

Deciphering the Roles of Extracellular Polymeric Substances (EPS) in Shaping Disinfection Kinetics through Permanent Removal via Genetic Disruption.

Extracellular polymeric substances (EPS) ubiquitously encapsulate microbes and play crucial roles in various environmental processes. However, understanding their complex interactions with dynamic bacterial behaviors, especially during the disinfection process, remains very limited. In this work, we investigated the impact of EPS on bacterial disinfection kinetics by developing a permanent EPS removal strategy. We genetically disrupted the synthesis of exopolysaccharides, the structural components of EPS, in Pseudomonas aeruginosa, a well-known EPS-producing opportunistic pathogen found in diverse environments, creating an EPS-deficient strain. This method ensured a lasting absence of EPS while maintaining bacterial integrity and viability, allowing for real-time in situ investigations of the roles of EPS in disinfection. Our findings indicate that removing EPS from bacteria substantially lowered their susceptibility threshold to disinfectants such as ozone, chloramine B, and free chlorine. This removal also substantially accelerated disinfection kinetics, shortened the resistance time, and increased disinfection efficiency, thereby enhancing the overall bactericidal effect. The absence of EPS was found to enhance bacterial motility and increase bacterial cell vulnerability to disinfectants, resulting in greater membrane damage and intensified reactive oxygen species (ROS) production upon exposure to disinfectants. These insights highlight the central role of EPS in bacterial defenses and offer promising implications for developing more effective disinfection strategies.

Critical review on the research of chemical structure, bioactivities, and mechanism of actions of Dendrobium officinale polysaccharide.

Dendrobium officinale (Tie-Pi-Shi-Hu) is a precious traditional Chinese medicine (TCM). The principal active components are polysaccharides (DOP), which have a high potency in therapeutic applications. However, limitations in structure analysis and underlying mechanism investigation impede its further research. This review systemically and critically summarises current understanding in both areas, and points out the influence of starch impurities and the role of gut microbiota in DOP research. As challenges faced in studying natural polysaccharide investigations are common, this review contributes to a broader understanding of polysaccharides beyond DOP.

Visual outcome of 25 Gauge vitrectomy for acute post operative infectious endophthalmitis.

BACKGROUND: The correlation between the change in foveal thickness measured using optical coherence tomography (OCT) following surgery for infectious endophthalmitis and preoperative and postoperative visual acuity is uncertain, and there are few pertinent studies on this topic. OBJECTIVE: We explored the variations in macular thickness using OCT after emergency vitrectomy for post-cataract infectious endophthalmitis and the relationship between macular thickness with changes in visual function. METHODS: We included 10 cases of post-cataract infectious endophthalmitis. Each patient underwent 25-G vitrectomy. RESULTS: The infection in all 10 patients was under control and visual function improved. Postoperative vitreous humor culture was positive in 8 patients, including 7 cases of coagulase-negative Staphylococcus epidermidis and 1 case of Lactobacillus acidophilus. The average age of these 10 patients was 71.60 ± 8.71 years (P< 0.05, two-tailed). There was no significant correlation between time 2 (the time of onset after cataract surgery) and visual prognosis. The average time 1 (the time of the vitrification surgery caused by the onset of the disease) was 1.45 ± 0.76 days (P< 0.05, two-tailed). The postoperative 3dVA ranged from 0.20 to 3.00, with an average visual acuity of 1.87 ± 1.12, which was superior to the preoperative value (P< 0.01, two-tailed). The correlation between the post3dVA and post 1mVA was significant. The post 1mVA ranged from 0.05 to 2.20, with an average visual acuity of 0.94 ± 0.74 (P< 0.05, two-tailed). The correlation between post 1mVA and post3mVA was significant. Also, paired t-tests comparing preoperative and postoperative visual acuity revealed a significant correlation (P< 0.05, two-tailed). The post3mVA was 0-1.00 with an average visual acuity of 0.44 ± 0.41. The postoperative foveal thickness ranged from 176.00 to 514.00 µm, with an average thickness of 281.10 ± 113.12 µm. CONCLUSION: Emergency 25-G minimally invasive vitrectomy can improve visual acuity and decrease the reoperation rate for patients who have acquired post-cataract infectious endophthalmitis. There were significant correlations between age, disease onset to operation time, preoperative and postoperative visual acuity, and postoperative macular thickness.

The neglected ammonia leaching calcium in anaerobic granular sludge.

Previous researches have primarily emphasized the deleterious impacts of NH4+ on anaerobic granular sludge due to its biotoxicity. Despite this, the role of NH4+ as a monovalent cation in leaching multivalent Ca2+, thereby hindering granule formation and undermining its stability, remains underappreciated. This study investigated the potential of NH4+ to leach Ca2+ from anaerobic granular sludges. The results indicated that a shock loading of NH4+ at a concentration of 900 mg/L caused a Ca2+ leaching of 57.1 mg/L at pH 7.0. In an acidified environment (pH 5.0), the shock loading resulted in a Ca2+ release of 127.3 mg/L, a magnitude 5.24 times greater than the control group. The leaching process modestly affected granular sludge activity and size but markedly compromised granular strength due to calcium loss. Subsequent to the NH4+ shock, the granular strength manifested a significant reduction, as evidenced by a 15-fold increase in protein release from the granules compared to the intact ones. Additionally, NH4+ shock altered the calcium partitioning within the granular sludge, resulting in a decrease in residual calcium and a concomitant increase in bound calcium, further affecting granular strength. This study underscores the overlooked significant phenomenon of NH4+ shock-leaching Ca2+ in anaerobic granular sludge, which warrants significant attention given to its rapid and deleterious effects on granular strength and the shift in calcium state.

Effects of Dietary Protein-to-Energy Ratios on Growth, Immune Response, Antioxidative Capacity, Liver and Intestinal Histology, and Growth-Related Gene Expression in Hybrid Yellow Catfish (Pelteobagrus fulvidraco ♀ × Pelteobagrus vachelli ♂).

This study is aimed at evaluating the effects of dietary protein-to-energy ratios on the growth, immunological response, antioxidative capacity, liver and intestinal histology, and growth-related gene expression of hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × Pelteobagrus vachelli ♂). Eight diets were formulated to form different protein/energy ratios of 84, 88, 90, 93, 95, 96, 99, and 103 mg/kcal (P/E84, P/E88, P/E90, P/E93, P/E95, P/E96, P/E99, and P/E103), respectively. These diets contain different levels of gross energy (GE), ranging from 4.13 to 4.76 kcal g-1. Seven hundred and twenty healthy fish (17.15 ± 0.02 g) were randomly dispersed into 24 rectangular fiberglass tanks with 8 treatments in triplicate groups. The fish fed a P/E ratio of 95 mg/kcal demonstrated the best growth and feed utilization. A significant (P < 0.05) increase in percent weight gain (WG%) and specific growth rate (SGR) was seen as the dietary P/E ratio ameliorated from P/E84 to P/E95, followed by a decreased pattern in these parameters. Feed conversion ratio (FCR) and daily feed intake (DFI) were significantly impacted by dietary P/E ratios (P < 0.05). Additionally, an optimum P/E ratio improved intestinal morphology. However, low or high P/E ratio diets can cause oxidative stress, impaired liver function, and significantly reduced nonspecific immunity. The expression of target of rapamycin (TOR) and insulin-like growth factor-1 (IGF1) genes in the liver was considerably influenced by dietary protein-to-energy ratios (P < 0.05). Based on the statistical analysis of WG% against the dietary P/E ratio, the optimal P/E ratio for the studied species was estimated to be 92.92 mg/kcal.

Cardiac arrest secondary to pulmonary embolism treated with extracorporeal cardiopulmonary resuscitation: Six case reports.

BACKGROUND: Massive pulmonary embolism (PE) results in extremely high mortality rates. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) can provide circulatory and oxygenation support and rescue patients with massive PE. However, there are relatively few studies of extracorporeal cardiopulmonary resuscitation (ECPR) in patients with cardiac arrest (CA) secondary to PE. The aim of the present study is to investigate the clinical use of ECPR in conjunction with heparin anticoagulation in patients with CA secondary to PE. CASE SUMMARY: We report the cases of six patients with CA secondary to PE treated with ECPR in the intensive care unit of our hospital between June 2020 and June 2022. All six patients experienced witnessed CA whilst in hospital. They had acute onset of severe respiratory distress, hypoxia, and shock rapidly followed by CA and were immediately given cardiopulmonary resuscitation and adjunctive VA-ECMO therapy. During hospitalization, pulmonary artery computed tomography angiography was performed to confirm the diagnosis of PE. Through anticoagulation management, mechanical ventilation, fluid management, and antibiotic treatment, five patients were successfully weaned from ECMO (83.33%), four patients survived for 30 d after discharge (66.67%), and two patients had good neurological outcomes (33.33%). CONCLUSION: For patients with CA secondary to massive PE, ECPR in conjunction with heparin anticoagulation may improve outcomes.

Upregulation of OTX2-AS1 is Associated With Immune Infiltration and Predicts Prognosis of Gastric Cancer.

BACKGROUND: It is unclear whether the long non-coding RNA (lncRNA) OTX2 antisense RNA 1 (OTX2-AS1) plays a pivotal role in gastric cancer (GC). An analysis of The Cancer Genome Atlas (TCGA) database data and bioinformatics was used to explore the relationship between OTX2-AS1 and GC in the current study. METHODS: We evaluated the relationship between clinical features and OTX2-AS1 expression, prognostic factors, and the significant involvement of OTX2-AS1 in function using various statistical methods, such as Kaplan-Meier method, Cox regression analysis, Gene Set Enrichment Analysis (GSEA), and immune infiltration analysis. GC cell lines were tested for OTX2-AS1 expression using qRT-PCR. RESULTS: A high level of OTX2-AS1 expression was significantly and negatively associated with Helicobacter pylori (H pylori) infection in GC patients (P = .006) and predicted a poorer overall survival (OS) (HR: 1.54; 95% CI: 1.10-2.14; P = .011), progression-free interval (PFI) (HR: 1.75; 95% CI: 1.22-2.51; P = .002) and disease-specific survival (DSS) (HR: 1.85; 95% CI: 1.21-2.85; P = .005) in GC patients. There was an independent correlation between OTX2-AS1 expression (HR: 1.771; 95% CI: 1.164-2.696; P = .008) and OS in patients with GC. There were differential enrichments for the OTX2-AS1 high expression phenotype in the olfactory transduction, G alpha (s) signaling events, keratinization, olfactory signaling pathway, and preimplantation embryo. OTX2-AS1 expression may be related to certain immune-infiltrating cells. Compared to gastric epithelial cells (GES-1), GC cell lines showed a significant increase in OTX2-AS1 expression. CONCLUSION: There was a significant association between OTX2-AS1 expression in GC patients and poor survival, suggesting that it may be a useful biomarker for prognosis and immunotherapy outcome of stomach adenocarcinoma (STAD) in GC.

An oligosaccharide marker for rapid authentication of edible bird's nest.

Edible bird's nest (EBN) is a popular and expensive food material. The limited supply and great demand result in the use of adulterants. The authenticity concern is raised due to the lack of appropriate quality markers. Herein, this study aims to provide a specific oligosaccharide marker for rapid EBN authentication. Comparing the benzocaine (ABEE)-labeled saccharide profiles of multiple batches of EBN and adulterants indicates seven unique EBN oligosaccharides. The most abundant one, named BNM001, was selected as a marker and characterized to be Neu5Ac (2-3) Gal by MS and NMR spectra. This new oligosaccharide marker enables a rapid authentication of EBN within 10 min. ABEE labelling of this marker further upgraded the accuracy and sensitivity of the LC-qTOF-MS quantitative analysis. The relative marker content was associated with the quality of EBN products. These results suggest a specific and efficient quality marker for rapid authentication of EBN and related products.

The protective effect of hesperidin on cardiac and renal tissue damage in DOCA/Salt hypertensive rats / 中国药理学通报

Aim To investigate the protective effect of hesperidin (HES) on cardiorenal damage induced by DOCA/Salt hypertension and the underlying mechanisms. Methods Eighteen male SD rats were randomly divided into normal group (Ctrl), model group (DOCA/Salt), and DOCA/Salt with hesperidin group (DOCA/Salt + HES). HES was administered for four weeks. Blood pressure, serum creatinine and blood urea nitrogen were measured. The pathological changes in heart and kidney were examined by HE, Masson and Sirius red staining. The expression of α-SMA, collagen I and TGF-β were detected by Western blot. The mRNA levels of Nlrp3, TNF-α, IL-1β, IL-6 and NOXs were measured using qRT-PCR. Results Compared with the model group, HES administration significantly attenuated the occurrence of DOCA/Salt hypertension, improved renal function indicators of hypertensive rats, reduced renal and cardiac fibrosis, deduced the expression of α-SMA, collagen I and TGF-β, inhibited the expression of Nlrp3, TNF-α, IL-1β and IL-6, and decreased the expression of NOXs in renal and cardiac tissues. Conclusions HES can delay the occurrence of hypertension and protect against hypertension-induced renal and cardiac tissue damage, which may be related to the reduction of inflammatory reaction and oxidative stress by HES.

Acute myocardial necrosis caused by aconitine poisoning: A case report.

BACKGROUND: Herbal medicine has a long history of use in the prevention and treatment of disease and is becoming increasingly popular globally. However, there are also widespread concerns about its safety. Among them, the cardiotoxicity of aconitine has been described. CASE SUMMARY: We report a case of a 61-year-old male with aconitine poisoning presenting with malignant arrhythmia and severe cardiogenic shock, which was successfully managed with aggressive advanced life support and heart transplantation. CONCLUSION: This is the first case wherein in vivo cardiac pathology was obtained, confirming that aconitine caused acute myocardial necrosis.

Recent advances in qualitative and quantitative analysis of polysaccharides in natural medicines: A critical review.

Polysaccharides from natural medicines, being safe and effective natural mixtures, show great potential to be developed into botanical drugs. However, there is yet one polysaccharide-based case that has fulfilled the Botanical Guidance definition of a botanical drug product. One of the reasons is the analytical methods commonly used for qualitative and quantitative analysis of polysaccharides fall far behind the quality control criteria of botanical drugs. Here we systemically reviewed the recent advances in analytical methods. A critical evaluation of the strength and weaknesses of these methods was provided, together with possible solutions to the difficulties. Mass spectrometry with or without robust chromatographic separation was increasingly employed. And scientists have made significant progress in simplifying polysaccharide quantification by depolymerizing it into oligosaccharides. This oligosaccharides-based strategy is promising for qualitative and quantitative analysis of polysaccharides. And continuous efforts are still needed to develop a standardized quality control method that is specific, accurate, repeatable, and applicable for analyzing individual components in natural medicine formulas.

Qualitative and Quantitative Analysis of Ejiao-Related Animal Gelatins through Peptide Markers Using LC-QTOF-MS/MS and Scheduled Multiple Reaction Monitoring (MRM) by LC-QQQ-MS/MS.

Donkey-hide gelatin, also called Ejiao (colla corii asini), is commonly used as a food health supplement and valuable Chinese medicine. Its growing popular demand and short supply make it a target for fraud, and many other animal gelatins can be found as adulterants. Authentication remains a quality concern. Peptide markers were developed by searching the protein database. However, donkeys and horses share the same database, and there is no specific marker for donkeys. Here, solutions are sought following a database-independent strategy. The peptide profiles of authentic samples of different animal gelatins were compared using LC-QTOF-MS/MS. Fourteen specific markers, including four donkey-specific, one horse-specific, three cattle-specific, and six pig-specific peptides, were successfully found. As these donkey-specific peptides are not included in the current proteomics database, their sequences were determined by de novo sequencing. A quantitative LC-QQQ multiple reaction monitoring (MRM) method was further developed to achieve highly sensitive and selective analysis. The specificity and applicability of these markers were confirmed by testing multiple authentic samples and 110 batches of commercial Ejiao products, 57 of which were found to be unqualified. These results suggest that these markers are specific and accurate for authentication purposes.

Assessing alterations of water level due to environmental water allocation at multiple temporal scales and its impact on water quality in Baiyangdian Lake, China.

Lakes in arid/semiarid regions face problems of insufficient inflow and degradation of water quality, which threaten the health of the lake ecosystem. Baiyangdian Lake (BYDL), the largest lake in the North China Plain, is confronted with such challenges. The objective of this study was to improve understanding of how changes in water level influence water quality in the BYDL at different temporal scales, especially related to implementations of intermittent environmental water allocation activities in the past two decades, by using data on monthly lake water level, climate factors of precipitation and temperature, and lake water quality. The Mann-Kendall method and continuous wavelet analysis revealed that the lake water level shows a significant decreasing trend after 1967, and the period of 16-year was identified as the principal period for 1950-2018. Based on cross-wavelet transform and wavelet coherence analysis, the periodic agreement and coherence between water level and climatic factors decreased after 1997, when environmental water allocations started, indicating that the influences of climatic factors, i.e., precipitation and temperature, became weak. By utilizing the cross-wavelet transform and wavelet coherence analysis methods, the relationships between lake water level and water quality parameters of chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus were investigated. We found that the change in source and amount of environmental water allocation is one possible reason for the temporal evolution in joint variability between lake water level and water quality. Meanwhile, a dilution effect of freshwater allocated to BYDL was detected in the time-frequency domain. However, the result also indicates that the driving mechanism of water quality is complex due to the combined impacts of water allocation, nonpoint source pollution in the rainy season, and nutrient release from lake sediment. Our findings improve the general understanding of changes in water level in lakes located in arid and semiarid regions under climate change and intensive human activities, and also provide valuable knowledge for decision making in aquatic ecosystem restoration of BYDL and other similar lakes.

Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry.

A novel method for the determination of ultra-trace cobalt by dispersive liquid-liquid microextraction (DLLME) coupled with graphite furnace atomic absorption spectrometry has been developed. It is based on the color reaction of Co2+ with 2-(5-bromo-2-pyridylazo)-5-dimethylaminoaniline (5-Br-PADMA) in a Britton-Robinson buffer solution at pH 6.0 to form stable hydrophobic chelates, which were separated and enriched by DLLME with 1,2-dichloroethane (CH2ClCH2Cl) as extraction and acetonitrile (CH3CN) as a dispersive solvent. The sedimented phase containing the chelates is then determined with GFAAS. Parameters that affect extraction efficiency, such as types and volumes of extraction and disperser solvents, pH of sample solution, extraction time, concentration of the chelating agent 5-Br-PADMA, and salt effect, were investigated. Under optimal conditions, the calibration graph was linear over the range 0.05-1.0 ng/mL, with a correlation coefficient of 0.9922 and a detection limit of 0.03 ng/mL. Preconcentration factor (PF) is calculated as the ratio of the aqueous solution volume (5 mL) to that of the organic phase volume (40 µL), and enrichment factor (EF) is calculated as the ratio of the slopes of the calibration graphs obtained with and without DLLME for 5.0 mL of sample solution, which were 120 and 112.5, respectively. The extraction efficiency, calculated by EF/PF·100, was 93.8%. The relative standard deviation (RSD) at the 0.5 ng/mL Co2+ level was 3.8% (n = 6). The method has been applied to the determination of trace cobalt in water samples with satisfactory results.

Qualitative and Quantitative Analysis of Edible Bird's Nest Based on Peptide Markers by LC-QTOF-MS/MS.

Edible bird's nest (EBN) is an expensive health food. There are many adulterants in the market. It remains challenging to discriminate EBN from its adulterants due to a lack of high-specificity markers. Besides, the current markers are confined to soluble fraction of EBN. Here, both soluble and insoluble fractions were analyzed by LC-QTOF-MS/MS. A total of 26 high-specificity peptides that were specific to EBN were selected as qualitative authentication markers. Among them, 10 markers can discriminate EBN from common adulterants, 13 markers discriminate white EBN from grass EBN/common adulterants, and 3 markers discriminate grass EBN from white EBN/common adulterants. Three of them, which showed high signal abundance (Peak area ≥ 106) and satisfactory linearity (R2 ≥ 0.995) with EBN references, were selected as the assay marker; and their peptide sequences were confidently identified by searching database/de novo sequencing. Based on these markers, a qualitative and quantitative analytical method was successfully developed and well-validated in terms of linearity, precision, repeatability, and accuracy. The method was subsequently applied to detect EBN products on the market. The results indicated that more than half of EBN products were not consistent with what the merchants claimed.

Evaluating the influence of different environmental water allocation schemes on the water level of a typical shallow lake in semiarid regions: From the perspective of an integrated modeling approach.

Many lakes in semiarid regions around the world rely on environmental water allocation to maintain the health of the lake ecosystem. However, under changing environments, the competition for water resources between human society and natural ecosystems has intensified. How to manage environmental water allocation more reasonably and precisely has become an important issue. The largest lake on the North China Plain, Baiyangdian Lake (BYDL), is a typical lake facing such challenges. To provide feasible strategies for sustainable water allocation to BYDL, with the proper parameterization of hydrological processes, this study developed a 10-day temporal scale lake water level prediction model to quantify how environmental water allocation regulates the BYDL water level under different hydroclimatic conditions. Evaluation of model performance revealed that environmental water allocation rather than natural climatic periodicity dominates the variation in the BYDL water level. The model structure could be further improved with consideration of more detailed observations of both the surface runoff entering BYDL and the water area beneath the canopy of the reeds in BYDL. Analysis of 72 model simulation scenarios indicated that water allocations from multiple sources are indispensable and that the water resources that guarantee maintaining the BYDL water level within the ecologically suitable range vary substantially under different hydroclimatic conditions. More elaborate allocation plans are required both to improve the water quality and health of the aquatic ecosystem of BYDL and to reduce the risk of flooding. The findings from this study are valuable for guiding the implementation of environmental water allocations to lakes in semiarid regions worldwide.