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A highly sensitive kanamycin electrochemiluminescence (ECL) switch sensor was constructed. A signal element consisting of ordered mesoporous carbon loaded with indium oxide nanoparticles/carbon quantum dots (OMC/In2O3/C-dots) was assembled on the surface of a gold electrode. Then, a molecularly imprinted polymer (MIP) was prepared on the modified electrode surface using kanamycin as the template molecule and o-aminophenol as the functional monomer. After kanamycin elution, the prepared sensor retained specific kanamycin recognition sites. OMC/In2O3 effectively amplified the ECL signal of the C-dots, thereby enhancing the detection sensitivity, whereas kanamycin quenched the signal. Therefore, the imprinted sites acted as a switch, providing a new method for detecting kanamycin. Under the optimal experimental conditions, the concentration of kanamycin was proportional to the degree of ECL quenching within a linear range of 5-4500 × 10-12 mol L-1 at 0.8 V (vs. Ag/AgCl electrode electrode), and the detection limit was 5.8 × 10-13 mol L-1. When applied to the detection of kanamycin in actual samples, such as chicken, duck, pork, and milk, the recovery for spiked samples was in the range 92.7-110%.
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Impressão Molecular , Nanopartículas , Pontos Quânticos , Canamicina , Carbono , Impressão Molecular/métodos , Polímeros Molecularmente Impressos , OuroRESUMO
A photoelectrochemical sensing platform based on ligand-variable metal clusters charge transfer was established for the quantitative assay of ronidazole (RNZ) using Ce-porphyrin-metal-organic frameworks/silver nanowires (Ce-Por-MOFs/AgNWs). Rod-like Ce-Por-MOFs and well-dispersed sub-50 nm AgNWs were prepared using a hydrothermal method and polyol strategy, and then through simple drop coating to yield Ce-Por-MOFs/AgNWs nanocomposites. We investigated the intrinsic semiconducting properties of the composites. More importantly, it was found that the variable-valence metal node can provide electronic defect states similar to those caused by multi-metal doping, synergizing with the surface plasmon effect of AgNWs, which significantly improved the photoelectric conversion efficiency, thereby resulting in excellent optoelectronic properties. In combination with molecular imprinting, a competitive type trace photoelectrochemical sensor for RNZ was constructed using Fe2+ as the electron donor and probe. Under optimal conditions, the sensor response is proportional to the logarithm of RNZ concentration in the range 0.1-104 nM with a detected limit of 0.038 nM. The recoveries ranged from 87.2 to 116% with relative standard deviations (RSDs) < 6.5% (n = 3) in milk sample. This work reveals the charge-transfer process of variable-valence metal nodes in MOFs during photoelectrochemical processes, which will provide new insights for the sensing application of variable-valence metal MOFs.
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Estruturas Metalorgânicas , Nanofios , Ligantes , Estruturas Metalorgânicas/química , Ronidazole , PrataRESUMO
Considering the limitations associated with existing methods for the detection of trace amounts of trichlorfon, this paper proposes a novel molecularly imprinted electrochemiluminescence (ECL) sensor for the detection of trichlorfon by utilizing the double enhancement effect of trichlorfon and Ag nanoparticles supported by multi-walled carbon nanotubes (MWCNTs/Ag NPs) in a luminol-H2O2 ECL system. Here, trichlorfon was electropolymerized on the surface of the MWCNT/Ag NP-modified gold nanoelectrode with o-phenylenediamine to prepare the molecularly imprinted polymer-based sensor. After eluting the trichlorfon, imprinted holes for the identification of trichlorfon were retained on the sensor, which were used as signal switches to obtain different ECL intensities through the adsorption of different concentrations of trichlorfon. The ECL signal of the sensitized luminol-H2O2 was doubly enhanced by the MWCNTs/Ag and trichlorfon, improving the sensitivity of the sensor. The trichlorfon concentration was positively correlated with the enhanced ECL intensity of the sensor in the range 5.0 × 10-8-5.0 × 10-11 mol L-1, and the detection limit of trichlorfon was 3.9 × 10-12 mol L-1. Moreover, the proposed sensor was successfully applied to the detection of trichlorfon residues in real samples, and the recovery ranged between 91.8 and 109%. A molecularly imprinted electrochemiluminescence sensor for trichlorfon detection by utilizing the double enhancement effect of trichlorfon and Ag nanoparticles supported by multi-walled carbon nanotubes in a luminol-H2O2 ECL system. The dual enhancement of the ECL signal improved the sensitivity of the sensor.
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Nanopartículas Metálicas , Nanotubos de Carbono , Peróxido de Hidrogênio , Medições Luminescentes/métodos , Luminol/química , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Prata , TriclorfonRESUMO
Risks from combined exposure to multiple chemicals in food have prompted a growing concern for their effect on human health. Risk management of chemical mixtures should be based on developing and harmonizing methodologies to scientifically evaluate their cumulative adverse effects. In this study, a simplified tiered approach of cumulative exposure assessment is described along with a case study of vegetables in China's Hainan province during 2012-2014. This case study could be a reference for the Chinese National Risk Assessment Programs for vegetable and fruit products. In the proposed assessment approach, Tier 1 acts as a screening tier to categorize and evaluate chemicals under a conservative scenario, and it prioritizes the pesticides of most concern. Tier 2 refines the grouping of substances from Tier 1 and normalizes the toxic potency of the chemicals to sum the exposure of chemical mixtures in a given assessment group. Tier 3 applies the refined exposure model and the input parameter distribution to create probabilistic models using Monte Carlo simulation. This approach will be helpful in the cumulative exposure assessment where data on pesticide residues are sufficient, but the individual dietary consumption is inadequate.
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Resíduos de Praguicidas , China , Monitoramento Ambiental , Contaminação de Alimentos/análise , Humanos , Resíduos de Praguicidas/análise , Medição de Risco , Estações do Ano , VerdurasRESUMO
A luminescent double recognition nanoprobe is described as a new strategy for the selective determination of chiral molecules. C-dots/Ir/Au fluorescent nanoparticles, synthesised under hydrothermal conditions, are used as a high-performance probe in combination with a molecularly imprinted polymer (MIP) and calix[6]arene as a double recognition element. Thiolated calix[6]arene is grafted on C-dots/Ir/Au as the first recognition element, which then forms a host-guest complex with the target molecule levodopa (L-DOPA). Subsequently, an MIP is prepared on the C-dots/Ir/Au (MIP/C-dots/Ir/Au) by chemical polymerisation. After the removal of L-DOPA, double recognition imprinting cavities are formed. The fluorescence intensity at 478 nm of the nanoprobe is effectively quenched by adsorption of L-DOPA on MIP/C-dots/Ir/Au, which provides a method for L-DOPA determination. Owing to the double recognition strategy, this method has excellent selectivity which can effectively avoid interference from enantiomer D-DOPA, and a imprinting factor of 7.1 is obtained for L-DOPA. This accurate and reliable method, with a wide linear range (5 × 10-10 to 1.2 × 10-7 mol L-1) and a low limit of detection (1.45 × 10-10 mol L-1), was successfully applied to the determination of L-DOPA in real samples, giving standard recoveries of 89.7-110.0%. Thus, the proposed sensing method provides a viable approach for the determination of a single enantiomer. Graphical abstract Schematic presentation of the MIP/C-dots/Ir/Au for L-DOPA detection. A fluorescence double chiral recognition nanoprobe is prepared of C-dots/Ir/Au nanoparticles as signal probe, and a molecularly imprinted polymer (MIP) and calix[6]arene as a double recognition element. Owing to the double recognition strategy, this method has strong specificity and can effectively avoid interference from enantiomers and racemates.
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The structure of hapten determines the performance of the antibody and the corresponding detection method. A new type of antigen was designed and synthesized to expose the spatial and characteristic structure of dinotefuran molecule, and a type of high-quality antibody was obtained. The IC50 value of the monoclonal antibody was 5.30 ng/mL and its cross-reactivity (CRs) was less than 2% when reacting with other structurally related analytes. The effects of spatial configurations of hapten on the antibody were visually analyzed while using the appropriate software according to the quality of the antibodies, which showed that the specificity of the antibody is closely related with the exposed structure of hapten. An ELISA assay with an IC50 of 5.66 ng/mL and a linear range of 1.95 to 16.29 ng/mL was developed. The results that were obtained from the ELISA and HPLC methods were equivalent. The results showed that spatial simulation is a crucial method that is used in the designing of hapten to obtain a sensitive and specific antibody. The application of this method will highlight the potential aim and improve the detection efficiency of ELISA.
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Antígenos/análise , Ensaio de Imunoadsorção Enzimática/métodos , Ensaio de Imunoadsorção Enzimática/normas , Guanidinas/análise , Neonicotinoides/análise , Nitrocompostos/análise , Animais , Anticorpos/imunologia , Reações Cruzadas , Feminino , Guanidinas/química , Haptenos/química , Hibridomas , Camundongos Endogâmicos BALB C , Neonicotinoides/química , Nitrocompostos/químicaRESUMO
The synthesis of celastrol analogues containing amino acid ester at the C(29) position and their evaluation for cytotoxic activities in vitro were reported. The MTT test showed that a set of derivatives with lower IC50 values than that of the positive control group cisplatin and the parent compound celastrol, which exhibited greater antiproliferative activities. The most potent title compounds 2a and 2e exhibited cytotoxic activities in vitro against HeLa and A549 cell lines with IC50 values of 0.371 and 0.237 µm, 0.235 and 0.109 µm, respectively. The apoptosis assay demonstrated that 2a and 2e can induces of A549 cell apoptosis in low concentrations. These results showed that 2a and 2e may be promising for further research as antitumor agents.
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Aminoácidos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Triterpenos/farmacologia , Aminoácidos/química , Antineoplásicos Fitogênicos/síntese química , Antineoplásicos Fitogênicos/química , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Células HeLa , Humanos , Estrutura Molecular , Triterpenos Pentacíclicos , Relação Estrutura-Atividade , Tripterygium/química , Triterpenos/síntese química , Triterpenos/química , Células Tumorais CultivadasRESUMO
An electrochemical microfluidic chip is described for the determination of the insecticide carbofuran. It is making use of a molecularly imprinted film (MIP) and a DNA aptamer as dual recognition units. The analyte (carbofuran) is transported to the MIP and captured at the identification site in the channel. Then, carbofuran is eluted with carbinol-acetic acid and transported to the DNA aptamer on the testing position of the chip. It is captured again, this time by the aptamer, and detected by differential pulse voltammetry (DPV). The dual recognition (by aptamer and MIP) results in outstanding selectivity. Additionally, graphene oxide-supported gold nanoparticles (GO-AuNPs) were used to improve the sensitivity of electrochemical detector. DPV response is linear in the 0.2 to 50 nM carbofuran concentration range at a potential of -1.2 V, with a 67 pM detection limit. The method has attractive features such as its potential for high throughput, high degree of automation, and high integration. Conceivably, the method may be extended to other analytes for which appropriate MIPs and aptamers are available. Graphical abstract Schematic of an electrochemical microfluidic chip for carbofuran detection based on a molecularly imprinted film (MIP) and a DNA aptamer as dual recognition units. In the chip, targets were recognized by MIP and aptamer, respectively. It shows promising potential for the design of electrochemical devices with high throughput, high automation, and high integration.
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We present novel magnetic composite nanospheres for the preparation of a nanoiron oxide/carbon dots/ß-cyclodextrin/molecularly imprinted polymer for the selective solid-phase extraction kelthane and pyridaben from vegetables. The molecularly imprinted polymer was synthesized on the surface of nano-iron oxide/carbon dots via a chemical polymerization procedure, where kelthane-ß-cyclodextrin and pyridaben-ß-cyclodextrin inclusion complexes were used as template molecules, and their adsorption behavior was investigated in detail. Characterization analysis and binding experiments revealed that magnetic composite nanospheres had outstanding magnetic properties, a large adsorption capacity, and high competitive selectivity for kelthane and pyridaben. The magnetic composite nanospheres were employed as an adsorbent in solid-phase extraction for the determination of kelthane and pyridaben in vegetable samples. The recoveries of kelthane and pyridaben were 92.8-105.2 and 94.4-104.6%, respectively.
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Residues of 14 pesticides were determined in 150 cowpea samples collected in five southern Chinese provinces in 2013 and 2014.70% samples were detected one or more residues. 61.3% samples were illegal mainly because of detection of unauthorized pesticides. 14.0% samples contained more than three pesticides. Deterministic and probabilistic methods were used to assess the chronic and acute risk of pesticides in cowpea to eight subgroups of people. Deterministic assessment showed that the estimated short-term intakes (ESTIs) of carbofuran were 1199.4%-2621.9% of the acute reference doses (ARfD) while the rates were 985.9%-4114.7% using probabilistic assessment. Probabilistic assessment showed 4.2%-7.8% subjects may suffer from unacceptable acute risk from carbofuran contaminated cowpeas from the five provinces (especially children). But undue concern is not necessary, because all the estimations are based on conservative assumption.
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Monitoramento Ambiental , Contaminação de Alimentos/análise , Resíduos de Praguicidas/análise , Vigna/química , Adolescente , Adulto , Criança , Pré-Escolar , China , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resíduos de Praguicidas/efeitos adversos , Medição de Risco , Vigna/efeitos adversos , Adulto JovemRESUMO
The acute toxicity and genotoxicity of carbendazim, two impurities (3-amino-2-hydroxyphenazine and 2,3-diaminophenazine) and one metabolite (2-aminobenzimidazole) to Eisenia foetida were assessed using artificial soil test and comet assay respectively. Acute toxicity results showed carbendazim was moderately toxic to the earthworms with 14 day-LC50 of 8.6 mg/kg dry soil while 3-amino-2-hydroxyphenazine, 2,3-diaminophenazine, and 2-aminobenzimidazole were of low toxicity with 14 day-LC50 values of 19.0, 14.9, and 27.7 mg/kg dry soil respectively (nominal concentration). The olive tail moment and percentage of DNA in the tail were used as genotoxicity indices, and carbendazim could significantly induce DNA damage to the earthworm coelomocytes with obviously positive dose- and duration-response relationships while the other three substances showed similar (p = 0.05) genotoxicity results to the negative controls in all of the tests.
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Benzimidazóis/toxicidade , Carbamatos/toxicidade , Oligoquetos/efeitos dos fármacos , Fenazinas/toxicidade , Animais , Ensaio Cometa , Dano ao DNARESUMO
The dissipation and residues of an eco-friendly bio-pesticide, spinosad, in cowpea under field conditions were studied using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MSMS) after Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction. The method exhibited good linearity with respect to spinosyn A and spinosyn D in solvent or blank cowpea matrix with correlation coefficients>0.99. Additionally, matrix effects were not significant in the range 0.987-1.014, and the average recoveries at three concentration levels were 75.1-91.1 and 79.4-90.5% for spinosyn A and spinosyn D, respectively. The intra- and inter-day relative standard deviations were 2.5-9.3 and 7.8-9.8% for spinosyn A, respectively, and 4.1-7.9 and 6.6-8.3% for spinosyn D, respectively. The limits of detection (LODs) and limits of quantification (LOQs) were 0.005 and 0.01 mg kg(-1), respectively, for spinosyn A, and 0.002 and 0.005 mg kg(-1), respectively, for spinosyn D. The dissipation of spinosad (sum of spinosyn A and spinosyn D) fitted well to first-order kinetics with half-lives of 0.9-1.5 days. The highest residue (HR) at pre-harvest interval (PHI) of 12 h was 0.321 mg kg(-1). Compared with the maximum residue limit (MRL) set by Codex, a PHI of at least 24 h was recommended. The estimated daily chronic intake of spinosad from cowpea was less than 0.14% of the acceptable daily intake (ADI). Therefore, the risk of consuming cowpea sprayed with spinosad under recommended field conditions was considered acceptable for the Chinese population.
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Monitoramento Ambiental , Macrolídeos/análise , Resíduos de Praguicidas/análise , Cromatografia Líquida , Combinação de Medicamentos , Meia-Vida , Cinética , Limite de Detecção , Medição de Risco , Espectrometria de Massas em TandemRESUMO
The interaction between 2-phenylpyrazolo[1,5-c]quinazoline (PQ) and DNA under physiological conditions was investigated using multi-spectroscopic techniques, atomic force microscopy and gel electrophoresis. The thermodynamic parameters were estimated and were discussed in detail. The results of fluorescence-quenching experiments indicated that the main interactive force between PQ and DNA was a hydrophobic interaction and that it was a static quenching process. Potassium iodide and single-strand (ss)DNA quenching studies, together with circular dichroism spectra implied groove binding of PQ with DNA. Atomic force microscopy and gel electrophoresis experiments suggested that there were no major conformational changes in DNA upon interaction with PQ. In addition, UV/vis absorption titration of DNA bases confirmed that PQ bound with DNA mainly through a minor groove interaction and preferentially interacted with adenine and thymine. We anticipate that this work will provide useful information for the application of quinazoline derivatives in the fields of medicinal and pharmaceutical chemistry.
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DNA/química , DNA/metabolismo , Quinazolinas/química , Sítios de Ligação , Dicroísmo Circular , DNA de Cadeia Simples/química , DNA de Cadeia Simples/metabolismo , Eletroforese em Gel de Ágar , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Microscopia de Força Atômica , Modelos Moleculares , Iodeto de Potássio/química , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , TermodinâmicaRESUMO
Objective: Sleep disorders is a worldwide public health problem. We sought to examine the association between sarcopenia, a decline in skeletal muscle mass and function, and sleep disorders within the adult demographic of the United States during the period spanning 2011 to 2018. Methods: Diagnosis of sarcopenia and sleep disorders was ascertained through appropriate calculations and a structured questionnaire. The primary correlation analysis was conducted using a weighted multivariate logistic regression model. Furthermore, to confirm the presence of a potential non-linear association between sarcopenia and sleep disorders, additional analyses were performed using multivariate logistic regression and restricted cubic spline (RCS) regression with dose-response curve analysis. Subgroup analyses were also conducted to explore the influence of relevant socio-demographic factors and other covariates. Results: The final analysis encompassed 5,616 participants. Model 4, inclusive of all pertinent covariates, revealed a positive correlation between sarcopenia and sleep disorders, yielding an odds ratio (OR) of 1.732 (95% CI: 1.182-2.547; P = 0.002). Further analysis, utilizing the restricted cubic spline model, indicated a decreasing trend in sleep disorders as sarcopenia indices rose. Stratified analyses across diverse variables underscored the significant impact of sarcopenia on sleep disorders prevalence in several subgroups. Specifically, males, individuals aged 40 and above, non-Hispanic whites, those with high school education or equivalent, unmarried individuals, obese individuals (BMI ≥ 30), alcohol drinkers, former smokers, diabetics, and those engaging in less rigorous recreational activities exhibited a more pronounced association between sarcopenia and sleep disorders. The incidence of sleep disorders exhibited an upward trend as the incidence of sarcopenia declined among study participants. Conclusions: In summary, our study provides evidence of an association between sarcopenia and the prevalence of sleep disorders, with a negative correlation observed between the sarcopenia index and the odds ratio of sleep disorders. These findings suggest that maintaining optimal muscle mass may have a beneficial impact on sleep-related issues. In terms of exploring the mechanisms underlying the relationship between sarcopenia and sleep disorders, more in-depth research is warranted to ascertain the definitive causal relationship.
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Residues of a fungicide suspension (12 % difenoconazole, 18 % azoxystrobin) in bananas and soil were studied under tropical and subtropical monsoon climates, in Hainan and Yunnan provinces, respectively. The half-lives in bananas were shorter in Hainan (difenoconazole: 8.4-10.7 days; azoxystrobin: 7.8-8.4 days) than Yunnan (difenoconazole: 11.3-13.0 days; azoxystrobin: 10.4-11.6 days), possibly because of the higher temperatures and solar radiation levels in Hainan. The half-lives in soil were shorter in Yunnan (difenoconazole: 15.5-16.7; azoxystrobin: 11.9-13.9 days) than Hainan (difenoconazole: 23.1-23.2 days; azoxystrobin: 16.0-16.1 days), possibly because the organic carbon content was higher and rainfall lower in Yunnan than Hainan. Their physico-chemical properties suggest difenoconazole and azoxystrobin should be stable in bananas and soil, but both decreased to safe concentrations by the minimum harvest time after spraying the mixture at the recommended dosage and 1.5 times that dosage, through physical, chemical, and biological processes.
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Dioxolanos/análise , Fungicidas Industriais/análise , Metacrilatos/análise , Musa/química , Resíduos de Praguicidas/análise , Pirimidinas/análise , Solo/química , Triazóis/análise , Agricultura , China , Clima , Meia-Vida , Cinética , EstrobilurinasRESUMO
A new microplate luminometry for the toxicity bioassay of chemicals on firefly luciferase, was developed using the multifunctional microplate reader (SpectraMax M5) to measure the luminous intensity of luciferase. Efects of luciferase concentration, luciferin concentration, ATP concentration, pH, temperature, and reaction time on the luminescence were systematically investigated. It was found that ATP exerted a biphasic response on the luciferase luminescence and the maximum relative light units (RLU) occurred at an ATP concentration of 1.1 x 10(-4) mol x L(-1). The method was successfully employed in the toxic effect test of NaF, NaCl, KBr and NaBF4 on luciferase. Using nonlinear least square technique, the dose-response curves (DRC) of the 4 chemicals were accurately fitted with the coefficient of determination (R2) between the fitted and observed responses being greater than 0.99. The median effective concentration (EC50) of the 4 chemicals were accurately measured from the DRC models. Compared with some literatures, the bioassay is a fast easy-operate and cost-effective method with high accuracy.
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Bioensaio , Luciferases/química , Trifosfato de Adenosina , Luciferina de Vaga-Lumes , Luz , Luminescência , Modelos Teóricos , TemperaturaRESUMO
Background: Opioid-free anesthesia (OFA) provides adequate analgesia and can reduce postoperative opioid consumption, but its efficacy in spontaneous ventilation video-assisted thoracic surgery (SV-VATS) has not been demonstrated. We aimed to investigate the hypothesis that OFA could provide the same perioperative pain control as opioid anesthesia (OA), maintain safe and stable respiration and hemodynamics during surgery, and improve postoperative recovery. Methods: Sixty eligible patients (OFA group: n=30; OA group: n=30) treated between September 15, 2022, and December 15, 2022, at The First Hospital of Guangzhou Medical University were included. They were randomized to receive standard balanced OFA with esketamine or OA with remifentanil combined with sufentanil. The primary outcome was the pain numeric rating score (NRS) at postoperative 24 h, and the secondary outcomes were intraoperative respiratory and hemodynamic data, opioid consumption, vasoactive drug dosage, and recovery in the post-anesthesia care unit and ward. Results: There was no significant difference in the postoperative pain scores and recovery quality between the two groups. The OFA group had a significantly lower dose of phenylephrine (P=0.001) and a lower incidence of hypotension (P=0.004) during surgery. The OFA group resumed spontaneous respiration faster (P<0.001) and had a higher quality of lung collapse (P=0.02). However, the total doses of propofol and dexmetomidine were higher (P=0.03 and P=0.02), and the time to consciousness was longer (P=0.039) in the OFA group. Conclusions: OFA provides the same level of postoperative pain control as OA, but it is more advantageous in maintaining circulatory and respiratory stability and improving the quality of pulmonary collapse in SV-VATS.
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A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method with multi-walled carbon nanotubes (MWCNTs) as a reversed-dispersive solid-phase extraction (r-DSPE) material combined with gas chromatography-mass spectrometry was developed for the determination of 14 pesticides in complex matrices. Four vegetables (leek, onion, ginger and garlic) were selected as the complex matrices for validating this new method. This technique involved the acetonitrile-based sample preparation and MWCNTs were used as the r-DSPE material in the cleanup step. Two important parameters influencing the MWCNTs efficiency, the external diameters and the amount of MWCNTs used, were investigated. Under the optimized conditions, recoveries of 78-110% were obtained for the target analytes in the complex matrices at two concentration levels of 0.02 and 0.2 mg/kg. In addition, the RSD values ranged from 1 to 13%. LOQs and LODs for 14 pesticides ranged from 2 to 20 µg/kg and from 1 to 6 µg/kg, respectively.
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Nanotubos de Carbono/química , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/isolamento & purificação , Extração em Fase Sólida/métodos , Verduras/química , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Extração em Fase Sólida/instrumentaçãoRESUMO
The presence of pesticide residues in cowpea raises serious health concerns. In this study, a novel, sensitive, high-performance method was developed to simultaneously analyze the residues of 35 pesticides in cowpea samples from growing areas in the Hainan province of China, from November 2018 to June 2021. The method employs modified QuEChERS sample pretreatment coupled with gas chromatography-tandem mass spectrometry. The limits of quantification of the 35 pesticides in the cowpea matrix ranged from 1.0 to 8.0 µg/kg. Twenty-seven of the 35 pesticides were detected, twelve of which are banned for use on legumes in China. Residues for ten pesticides in 17.1% of the samples exceeded their MRLs, with the highest exceedance of 380% observed in difenoconazole. Moreover, 80.8% of the samples contained one or more pesticide residues, with the most frequently detected pesticide being chlorfenapyr with a detection rate of 46.3%. In addition, the pesticide triazophos was detected through different years and regions. Notably, the chronic dietary exposure risk (%ADI) of the detected pesticides, evaluated from the national estimated acceptable daily intake, was lower than 100% in Chinese people of different age groups.
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Resíduos de Praguicidas , Vigna , China , Ingestão de Alimentos , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Resíduos de Praguicidas/análise , Medição de RiscoRESUMO
Metal-organic frameworks (MOFs) prepared via typical procedures tend to exhibit issues like poor water stability and poor conductivity, which hinder their application in electrochemical sensing. Herein, we report a strategy for the preparation of mixed-valence ultrafine one-dimensional Ce-MOF nanowires based on a micelle-assisted biomimetic route and subsequent investigation into their growth mechanism. The prepared mixed-valence Ce-MOF nanowires exhibited a typical size of â¼50 nm and were found to present good water stability and high conductivity. On this basis, we examined the introduction of these nanowires into the luminol hydrogen peroxide luminescence system and proposed a novel dual-route self-circulating electrochemiluminescence (ECL) catalytic amplification mechanism. Finally, in combination with molecular imprinting, a MOF-based ECL sensor was developed for the detection of trace amounts of imidacloprid in plant-derived foods. This sensor exhibited a linearity of 2-120 nM and a detection limit of 0.34 nM. Thus, we proposed not only a novel route to MOF downsizing but also a facile and robust methodology for the design of a MOF-based molecular imprinting ECL sensor.