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1.
Anal Methods ; 2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34095915

RESUMO

A device coupled with an automatic gas chromatography injection sampler for high-throughput liquid-liquid microextraction has been proposed in this study. This study's main objective was to devise a trap vial directly placed in an automatic liquid sampler (ALS) to collect and inject the extractant without a transfer step. Sixteen groups of microextraction procedures were performed simultaneously to increase the overall efficiency. The experimental parameters of the extraction method were optimized using a central composite design. Under the optimal conditions, the benzene derivatives' calibration curve was linear in the range of 0.1-200 µg L-1. The limit of detection (LOD) ranged from 0.016 to 0.16 µg L-1, and the limit of quantitation (LOQ) ranged from 0.046 to 0.50 µg L-1. The enrichment factors (EFs) ranged from 254 to 1094. Intraday and interday precision were found to be in the range of 2.2-6.2% (n = 3) and 4.0-6.3% (n = 9), respectively. The relative recovery of the four aqueous samples ranged from 69% to 121%. These experimental results indicated that the proposed device is reliable. Furthermore, it is simple, convenient and high-throughput.

2.
Fitoterapia ; 152: 104926, 2021 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-33991602

RESUMO

Dengratiol A (1), an unprecedented bibenzyl derivative bearing a tropolone unit together with three pairs of bibenzyl enantiomers (±)-dengratiols B-D [(±)-2-(±)-4], were isolated from Dendrobium gratiossimum Rchb.f. The resolution of enantiomers was performed with chiral HPLC. Their structures were characterized by extensive spectroscopic data analysis and calculated electronic circular dichroism (ECD). A hypothetical biosynthetic pathway for 1 is proposed. Biological assay revealed that (-)-2 showed moderate antiviral effect against IAV with IC50 value of 6.3 µM, and (±)-2 displayed cytotoxic activities against five human tumor cell lines with IC50 values ranging from 15.5 to 42.5 µM.

3.
Biosens Bioelectron ; 182: 113188, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33799030

RESUMO

Food safety is currently a significant issue for human life and health. Various fluorescent nanomaterials have been applied in the point-of-care test (POCT) for food safety as labeling materials. However, previous fluorescent nanomaterials can cause aggregation-caused quenching (ACQ), thus reducing the detection sensitivity. Conversely, aggregation-induced emission luminogens (AIEgens) are promising candidates for POCT in the food safety field because they can enhance detection sensitivity and throughput. Mycotoxins, such as aflatoxin B1 (AFB1) and cyclopiazonic acid (CPA), are a primary threat to human life and health and a significant food safety issue, and their on-site detection from farm to table is needed. Herein, an ultrasensitive point-of-care test was developed based on TPE-Br, a blue-emissive tetraphenylethylene derivative AIEgen. Under optimal conditions, this AIEgen-based lateral-flow biosensor (ALFB) allowed for a rapid response of 8 min toward AFB1 and CPA detection, with considerable sensitivities of 0.003 and 0.01 ng/mL in peanut matrices, respectively. In peanut matrices, the recoveries were 90.3%-110.0% for both mycotoxins, with relative standard deviations (RSDs) below 6%. The ALFB was further validated via UPLC-MS/MS using spiked peanut samples. AIEgens open an avenue for on-site, ultrasensitive, high-throughput detection methods and can be extensively used in point-of-care tests in food safety.


Assuntos
Aflatoxina B1 , Técnicas Biossensoriais , Aflatoxina B1/análise , Cromatografia Líquida , Contaminação de Alimentos/análise , Humanos , Indóis , Limite de Detecção , Testes Imediatos , Espectrometria de Massas em Tandem
4.
Clin Chem Lab Med ; 2021 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33882205

RESUMO

OBJECTIVES: Currently there is no validated method to predict renal reversal and recovery after acute kidney injury (AKI). As exosomes have the potential for AKI prognosis and CD26 is involved in the mechanisms in AKI, this study aims to investigate whether urinary exosomal CD26 is associated with renal-related outcomes and explore its prospect as a novel prognosis biomarker. METHODS: This was a single-center, prospective cohort study. A total of 133 AKI patients and 68 non-AKI patients admitted to ICU in Qilu Hospital Shandong University from January 2017 to January 2018. Urine samples were collected at enrollment and the relative expression of CD26 (CD26 percentage) in urinary exosomes was examined, that was then categorized into a low-CD26 level and a high-CD26 level. RESULTS: CD26 percentage was significantly lower in the AKI cohort than in the control cohort. Within the AKI cohort, a high-CD26 level was associated with lower incidence of major adverse kidney events within 90 days, but higher incidence of reversal within 28 days. In AKI survivors, a high-CD26 level had a 4.67-, 3.50- and 4.66-fold higher odds than a low-CD26 level for early reversal, recovery and reversal, respectively, after adjustment for clinical factors. Prediction performance was moderate for AKI survivors but improved for non-septic AKI survivors. CONCLUSIONS: Urinary exosomal CD26 is associated with renal reversal and recovery from AKI and is thus a promising prognosis biomarker.

5.
Biosens Bioelectron ; 185: 113278, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-33930751

RESUMO

The long-term toxic effects of okadaic acid (OA) in shellfish pose a serious threat to public health, negatively impacting the development of the shellfish aquaculture industry. In this study, a novel competitive near-infrared-mediated photoelectrochemical immunosorbent assay (cNIR-PECIA) was developed for ultrasensitive and highly selective detection of OA based on NaYF4:Yb, Tm upconversion nanophosphors (UCNPs) and a flower-like WO3-modified screen-printed electrode (FL-WO3 SPE). The UCNPs function as a self-powder to convert NIR excitation into visible emissions. FL-WO3 fully utilizes the visible illumination and induces the separation of electron-hole pairs, thus generating a photocurrent. After conjugating monoclonal antibodies against OA on UCNPs (UCNPs-Ab), the bright PEC immunoprobe selectively captured OA molecules, which were then determined by a competitive indirect immunosorbent assay. Under optimal conditions, the 50% inhibitory concentration of the immunosensor was 0.09 ng mL-1. The OA concentration had a linear relationship with the antibody binding rate in the range of 0.01-60 ng mL-1 with an extremely low detection limit of 0.007 ng mL-1. Finally, the proposed cNIR-PECIA was successfully utilized to analyze OA content in mussel samples. This study affords new ideas for constructing NIR PEC sensors by using upconversion luminescent materials to match semiconductors. The superior sensing properties indicate their potential applicability in food safety analysis.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Eletrodos , Imunoensaio , Imunoadsorventes , Ácido Okadáico
6.
BMC Med Educ ; 21(1): 194, 2021 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-33823845

RESUMO

BACKGROUND: We combined anatomy with imaging, transformed the 2D information of various imaging techniques into 3D information, and form the assessment system of real medical imaging cases in order to make up for the deficiencies in the current teaching of the medical imaging technology students. METHODS: A total of 460 medical imaging students were selected and randomly divided into two groups. The research group received the teaching of the fusion of the original CT and MR data 3D model and the original image combined with 3D anatomical image. CT and MRI data are imported through load DICOM of 3D slicer. Different tissues and organs are segmented by threshold and watershed algorithm of segment editor module. Models are exported through export / import models and label maps in segmentation. Save the NHDR file of the original data and Obj file of the corresponding model through save the NHDR and corresponding Obj files are loaded into probe 1.0 software. The software can give different colors to the three-dimensional models of different organs or tissues to display the stereo models and related data, and display the hook edges of organ models on coronal, sagittal and axial images. At the same time, annotation can be established in the corresponding anatomical position. Finally, it can be saved as a single file of Hwl, and the teaching can be opened at any time through the program of probe 1.0. Statistical analysis Academic self-efficacy scale and Self-directed learning ability scale was adopted by self-directed learning evaluation scale between two groups. RESULTS: Compare the theoretical scores and case analysis scores of the two groups. The scores of the study and control groups were significantly higher than those of the control group. Before the experiment, no significant difference was detected in the self-efficacy of learning ability and learning behavior between the two groups, while after the experiment, these differences between the two groups were statistically significan. Moreover, the learning ability self-efficacy and learning behavior of the two groups of students after the experiment was significantly higher than that before the experiment. The self-efficacy of the learning behavior of the control group was higher after the experiment than that before the experiment, albeit the difference was not statistically significant. CONCLUSIONS: The modern, information-based and humanized experimental teaching mode will be constantly improved under the support of PACS system in order to optimize the medical imaging teaching activities for the development of modern medical education.


Assuntos
Imageamento Tridimensional , Estudantes de Medicina , Humanos , Aprendizagem , Imageamento por Ressonância Magnética , Ensino , Tecnologia
7.
Sci Rep ; 11(1): 5681, 2021 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-33707573

RESUMO

Accumulating evidence has implicated dietary factors as important risks for rheumatoid arthritis (RA) development, but analyses of the effects of red meat consumption on RA have yielded diverging results. The aim of this study was to explore the association between red meat and RA in a large-scale, cross-sectional study. From June to December 2016, a total of 733 patients were investigated, from which 707 participants were included in the analysis. These patients were divided into two groups according to their consumption of red meat (< 100 g/day; ≥ 100 g/day). The intake of red meat was assessed via physician-administered questionnaire. Generalized linear models were used to analyze relationships between the red meat intake and RA, adjusting for potential confounders including demographic, clinical, laboratory, and other dietary factors. Compared with low-intake red meat RA patients, high-intake red meat patients had an earlier onset age (p = 0.02) and had higher BMI (p = 0.003). The age at disease onset for the high-intake patients was 6.46 years earlier than for low-intake patients, after adjustment for demographic and other possible confounders (ß = - 6.46, 95% CI - 9.77, - 3.15; p = 0.0001). Further, stratified analyses showed that this inverse association of red meat intake with RA onset age was especially evident in smokers and overweight patients (BMI ≥ 24 kg/m2). In conclusion, high-intake red meat is associated with early onset of RA, especially in smokers or overweight patients. The findings indicate that eating less red meat could be a recommendation given to patients at risk for RA development.

8.
Biochem Biophys Res Commun ; 553: 134-140, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33770578

RESUMO

Ischemia-reperfusion injury (IR) is the leading cause of acute kidney injury (AKI). No effective drugs to treat IR-related AKI are currently available. Recent pre-clinical trials have evaluated the therapeutic potential of extracellular vesicles-exosomes to chronic kidney disease. Here, we found exosomes derived from the tubular epithelial cell in IR condition (ExoIR) enriched CD26, compared with control (ExoNormal). Tracking exosomes in vivo certified tubular epithelial cell uptake exosomes. We have isolated exosomes with overexpression of CD26 (ExoCD26+) from culture media from tubular epithelial cell line transferred by adenovirus vectors. After administration of exosomes (100 mg) or bovine serum albumin (BSA, equivalent protein control) in IR or sham operation mice after 72 h via tail vein injection, the renal function impairment and histology injury were relived in mice receiving ExoCD26+. Immunofluorescence staining with proliferating cell nuclear antigen revealed ExoCD26+ recovered proliferation of cells partly after IR injury. Cell cycle modulator, p53 and p21 were upregulated in IR mice receiving BSA control, ExoNormal, and ExoIR. ExoCD26+ significantly blunt this protein upregulation. Inflammatory cell infiltration and chemokine receptor (CXCR4) were dissipated in IR mice receiving ExoCD26+. Downstream chemokine of CXCR4, stromal derived factor-1 (SDF1) also decreased after administration of ExoCD26+ in IR mice. Finally, ExoCD26+ suppressed inundant collagenⅠ expression in IR kidney. In conclusion, Tubular epithelial cells derived-exosomes containing CD26 might be one of the therapy modes for IR-AKI by maintaining proliferation and dissipating inflammation.

9.
Artigo em Inglês | MEDLINE | ID: mdl-33723778

RESUMO

Soil immobilizes a considerable proportion of carbon (C) as organic matter in terrestrial ecosystems and is thus critical to stabilize the global climate system. Atmospheric nitrogen (N) deposition could influence soil C storage and stabilization, but how N deposition changes soil organic C (SOC) fractions and lability remains elusive. We investigated the effects of 3-year-period N inputs on SOC fractions and lability along three soil depths (0-10, 10-20, and 20-40 cm) in a tropical forest of southern China. Results showed that N additions did not significantly change contents of SOC fractions and the C lability, either in bulk or aggregate-based soils at any of the three depths, and it showed no significant interaction with soil aggregate or soil depth. The SOC content was 43.7 ± 1.5, 18.2 ± 1.0, and 10.7 ± 0.4 mg g-1 at the three soil layers downwards, with the non-readily oxidizable SOC (NROC) contributing over 70% while the remaining SOC consisting of readily oxidizable SOC at each soil layer. Moreover, contents of SOC and NROC were consistently higher in small soil aggregates, but the C decrement with increasing size of soil aggregates declined along soil profile downwards. This scenario suggests that physical protection of the small soil aggregate is limited, but its greater specific surface area could obviously contribute to the SOC pattern among soil aggregates. These results indicate that the highly developed forests could be resistant to short-term N deposition, even with a high load, to maintain its SOC stabilization.

11.
Environ Int ; 148: 106374, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33476788

RESUMO

BACKGROUND: The association between exposure to organochlorine pesticides (OCPs) and infant growth has been reported contradictorily in previous studies. Few studies have investigated the effects of prenatal exposure to OCPs on infant growth assessed longitudinally at multiple time points. OBJECTIVES: The purpose of the study was to examine the associations between prenatal exposure to OCPs and infant growth at birth, 6, 12 and 24 months of age, and further to explore the potential sex-specific effects. METHODS: The study population included 1039 mother-infant pairs who participated in a birth cohort study in Wuhan, China. The weight, length and body mass index (BMI) z-score of infants were measured and calculated at birth, 6, 12 and 24 months of age. The overweight status was defined as BMI z-score ≥ 85th percentile according to the standard of World Health Organization. The concentrations of OCPs were measured in cord serum, including hexachlorocyclohexanes (HCHs, consisted of α-HCH, ß-HCH, and γ-HCH), p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) and its metabolites: p,p'-dichlorodiphenyldichloroethane (p,p'-DDD), and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE). Generalized linear models were applied to estimate the associations of cord OCPs with infant growth parameters. A group-based semiparametric mixture model was used to estimate growth patterns of infants. Linear-mixed growth curve models were used to examine relationships between predicted growth trajectories and prenatal exposure to OCPs. Weighted quantile sum regression (WQSR) analyses were used to estimate the mixture effects of OCPs on infant growth. RESULTS: Higher cord serum ß-HCH concentrations were associated with higher BMI z-score at 12 [ß = 0.07, 95%CI: 0.01, 0.13] and 24 months of age [ß = 0.08, 95% CI: 0.02, 0.14]. Similar patterns were observed for relationships of γ-HCH [ß = 0.04, 95%CI: 0.01, 0.07] and p,p'-DDT [ß = 0.03, 95% CI: 0.00, 0.06] with BMI z-score at 6 and 12 months of age, respectively. However, higher cord serum p,p'-DDE concentrations were associated with a reduction of BMI z-score at 6 months of age [ß = -0.07, 95% CI: -0.12, -0.01]. Cord serum ß-HCH was also positively associated with the risk of overweight at 12 months of age [RR = 1.16, 95% CI (1.02, 1.33), for the medium vs the lowest tertile]. Among girls, the effects of ß-HCH on BMI z-score and overweight status were stronger than boys at 12 and 24 months of age. No statistically significant relationships of other OCPs with infant growth were observed. CONCLUSIONS: Prenatal exposure to ß-HCH was associated with increased BMI z-score and higher risk of overweight status in infants especially at 12 and 24 months of age, which seemed to be stronger in girls.


Assuntos
Hidrocarbonetos Clorados , Praguicidas , Efeitos Tardios da Exposição Pré-Natal , China , Estudos de Coortes , Monitoramento Ambiental , Feminino , Humanos , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/toxicidade , Lactente , Estudos Longitudinais , Masculino , Praguicidas/análise , Praguicidas/toxicidade , Gravidez
12.
Food Chem ; 347: 128960, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33461116

RESUMO

In this paper, temperature sensitive polymer p(MAH-ß-CD-co-NIPAM) was used as extraction in DLLME, because its phase transition behavior can be observed at room temperature due to Hofmeister and non-co-solvent effect. The whole pretreatment process is simple and fast, and the extraction process did not require dispersant to assist dispersion and centrifugation to collect the adsorbent. A new analytical method based on DLLME coupled with HPLC-UV was developed to detect five types of BPs in milk and take-out packaging. The limits of detection ranged from 0.44 to 1.60 ng mL-1 (S/N = 3). The relative recoveries of 5 BPs in food packaging were in the range of 91.08-108.04%.


Assuntos
Embalagem de Alimentos , Limite de Detecção , Microextração em Fase Líquida/métodos , Polímeros/química , Temperatura , Cromatografia Líquida de Alta Pressão , Solventes/química , Fatores de Tempo
13.
Talanta ; 221: 121447, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33076071

RESUMO

As a main contaminant in fish, microcystin-LR (MC-LR) leads to serious liver problems; therefore, the development of MC-LR sensors is important to guarantee aquatic food safety. In this work, a near-infrared (NIR) light-excited photoelectrochemical (PEC) immunosensor was developed through conjugation of Ag2S cubes with Au nanoparticles (NPs) to determine MC-LR residues in fish. Specifically, as a narrow-band semiconducting material, Ag2S is capable of absorbing NIR light. Taking advantage of the localized surface plasmon resonance (LSPR) effect along with good conductivity of AuNPs, the developed AuNP/Ag2S/fluorine-doped tin oxide (FTO) owns much higher photoelectric conversion efficiency, and the photocurrent is 5.3 times that of Ag2S FTO. Subsequently, the NIR-driven AuNP/Ag2S/FTO was used to immobilize antibodies (Abs) for MC-LR. Their specificity to MC-LR led to steric effects and limited surface electron transfer, causing reduce of the photocurrent. Through AuNP/Ag2S-composite amplification and immunological specificity, the PEC immunosensor can quantitatively measure MC-LR with a wide linear range, 10 pg L-1 to 10 µg L-1, and a much low detection limit, 7 pg L-1 (S/N = 3). Finally, the NIR PEC sensor was employed in the analysis of MC-LR contents in fish. This work reveals the NIR-responsive ability of Ag2S cubes and deepens understanding the role of AuNPs in the PEC process. Due to the superior properties, the developed NIR PEC immunosensor has been demonstrated as a promising method for analysis of biological samples.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Animais , Técnicas Eletroquímicas , Ouro , Imunoensaio , Limite de Detecção , Toxinas Marinhas , Microcistinas , Prata
14.
Sci Total Environ ; 753: 141949, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32891999

RESUMO

Bisphenol S (BPS) is the major substitute for the production of bisphenol A (BPA)-free products and detected in both food and environment. Although the relationship between BPA exposure and increased risk of obesity and diabetes has been noted, the potential influence of BPS is not fully understood. Herein, a non-targeted lipidomic study was performed to explore BPA/BPS exposure actions using the 3T3-L1 preadipocyte differentiation model, and revealed the comprehensive lipidome disturbance induced by either BPA or BPS exposure at different doses of 0.01, 1 and 100 µM. BPA was more potent than BPS in disturbance of lipid metabolism. A considerable similarity of BPS exposure to BPA was discovered. The key lipid remodeling in response to exposure was found to involve the cardiolipins, phosphatidylglycerols and fatty acids metabolic pathways, providing novel clues of potential mechanism in which both BPA and BPS exposure could be associated with increased risk of insulin resistance. Our study supplies the perspective into the lipidome response to environmental stress induced by BPA/BPS, and shows that BPA-free products are not necessarily safer. Substitution of BPA by its structural analog BPS should be therefore performed with caution.


Assuntos
Compostos Benzidrílicos , Lipidômica , Animais , Compostos Benzidrílicos/toxicidade , Camundongos , Fenóis/toxicidade , Sulfonas
15.
J Wound Ostomy Continence Nurs ; 47(4): 343-348, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33290011

RESUMO

PURPOSE: The purpose of our study was to investigate the association between cardiopulmonary bypass (CPB) duration and the incidence of pressure injuries (PIs) in patients undergoing cardiovascular surgery. DESIGN: Retrospective chart review. SUBJECTS AND SETTING: Two hundred and eighty-eight patients who underwent cardiovascular surgery with CPB from January 2016 through December 2016 in a 2000-bed general hospital, which integrates medical service, education, and research and in which 300 to 350 cardiovascular surgical procedures with CPB are performed each year. METHODS: We retrospectively collected data from patients' medical records. Univariate analysis and multivariate logistic regression analysis were performed to identify the independent risk factors for the development of PI. In addition, a simple linear regression model was conducted to assess the relationship between CPB duration and PI development. RESULTS: Of the 288 patients, 56 developed 80 PIs, with an incidence of 19.4% (95% confidence interval, 14.9%-24.3%). Multivariate logistic regression analysis showed that CPB duration, use of vasoactive drugs, and diabetes mellitus were independent risk factors for the development of PIs in patients receiving cardiovascular surgery. Median CPB duration was significantly longer in the group with PIs compared with the group without PIs (144 [range 48-415] minutes compared with 102.5 [range 16-678] minutes, P = .000). This result was consistent in the subgroup analysis of pediatric and adult patients. Pressure injuries also increased proportionally with CPB duration, from 12.2% at 60 minutes or shorter to 45.5% at more than 300 minutes (P = .002, R = 0.936). CONCLUSIONS: The CPB duration, use of vasoactive drugs, and presence of diabetes mellitus are independent risk factors for the development of PIs in patients undergoing cardiovascular surgery with CPB. Our findings indicated that PI incidence increased incrementally with the duration of CPB. We recommend implementing measures to prevent PIs in cardiovascular surgical patients, especially those undergoing prolonged CPB, receiving vasoactive drugs, and diagnosed with diabetes.

16.
Front Genet ; 11: 575680, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33193688

RESUMO

Long non-coding RNAs (lncRNAs) emerge as critical regulators across a wide variety of biological functions in living organisms. However, to date, no systematic characterization of lncRNAs has been investigated in the ectoparasitic mite Varroa destructor, the most severe biotic threat to honey bees worldwide. Here, we performed an initial genome-wide identification of lncRNAs in V. destructor via high-throughput sequencing technology and reported, for the first time, the transcriptomic landscape of lncRNAs in the devastating parasite. By means of a lncRNA identification pipeline, 6,645 novel lncRNA transcripts, encoded by 3,897 gene loci, were identified, including 2,066 sense lncRNAs, 2,772 lincRNAs, and 1,807 lncNATs. Compared with protein-coding mRNAs, V. destructor lncRNAs are shorter in terms of full length, as well as of the ORF length, contain less exons, and express at lower level. GO term and KEGG pathway enrichment analyses of the lncRNA target genes demonstrated that these predicted lncRNAs may be potentially responsible for the regulatory functions of cellular and biological progresses in the reproductive phase of V. destructor. To our knowledge, this is the first catalog of lncRNA profile in the parasitiformes species, providing a valuable resource for genetic and genomic studies. Understanding the characteristics and features of lncRNAs in V. destructor would promote sustainable parasite control.

17.
Sci Total Environ ; : 143428, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33168250

RESUMO

Potentially toxic element (PTE) pollution is considered as the main soil environmental problem in the world. Source apportionment and spatial pattern of soil PTEs are essential for soil management. US-EPA positive matrix factorization (EPAPMF) and sequential Gaussian simulation (SGS) are general modeling tools for source apportionment and spatial distribution, respectively. Factor analysis with nonnegative constraints (FA-NNC) and stochastic partial derivative equations (SPDE) provided potential tools for this issue. We compared the performance of FA-NNC with PMF and the performance of SPDE with SGS, based on a dataset containing 9 PTEs in 285 topsoil samples. Three factors were determined by the two receptor models, and the source contributions were similar, suggesting that FA-NNC can validly identify quantitative sources of soil PTEs. The average source contributions were calculated based on the PMF and FA-NNC. Natural sources dominated the contents of As, Co, Cr, Cu, Ni, and Zn and affected 56.0%, 38.7%, and 84.8% of the Cd, Hg, and Pb concentrations, respectively. A total of 59.8% of Hg and 12.0% of Pb were associated with atmospheric deposition from coal combustion, industrial and traffic emissions, respectively. Agricultural and industrial activities contributed 37.2% of Cd concentration. SPDE proved to be an effective geostatistical technique to simulate the spatial patterns of soil PTEs with higher prediction accuracy than SGS. Co, Cr, Cu, and Ni had similar spatial patterns with hotspots randomly distributed across the study area. The common hotspots of As, Cd, Hg, Pb, and Zn in central parts inherited their high geochemical background in mudstone, while intensive human inputs in these areas also contributed to the accumulation of Cd, Hg, and Pb.

18.
Mikrochim Acta ; 187(12): 653, 2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33175235

RESUMO

To simultaneously detect two metabolites of Aspergillus flavus, namely, cyclopiazonic acid (CPA) and aflatoxin (AFT), an ultrasensitive monoclonal antibody (mAb) YTT-2 against CPA was developed and characterized, with sensitivity to CPA of 1.32 ng mL-1. Along with the previously homemade mAb 1C11 against AFT, two mAbs were used to develop time-resolved fluorescence immunoprobes or gold immunoprobes. We developed two multiple-analyte paper immunosensors including time-resolved fluorescent immunochromatographic assay (TRFICA) and gold immunochromatographic assay (GICA) for the simultaneous determination of CPA and AFT. The TRFICA showed limits of determination (LODs) of 0.21 and 0.004 ng mL-1, while the GICA showed LODs of 0.33 and 0.01 ng mL-1 for CPA and AFT, respectively. To validate the specificity of the two rapid immunoassays, rice, corn and peanut samples were spiked with different concentrations of CPA and AFT. The two methods showed satisfactory recoveries (76.39~90.82% for CPA and 84.60~94.45% for AFT) and coefficients of variation of 3.50~7.80% for CPA and 4.12~13.90% for AFT. The results indicated that the TRFICA could complete the test within 5 min and had lower LODs and linear ranges, compared with that of GICA. The method developed in this work can be widely applied to the rapid and quantitative simultaneous determination of multiple harmful metabolites in fungi for food safety and health care. Graphical abstract.

19.
Anal Methods ; 12(18): 2391-2397, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32930265

RESUMO

A method for the aptamer-based determination of chloramphenicol (CAP) was developed by exploiting the peroxidase mimicking activity of hemin. The method includes two hemin-modified DNA probes termed P1 and P2. P1, which was modified at its 5' end with one hemin monomer, contains the CAP-binding sequence. The hybridization between P1 and P2 brings the two hemin monomers in close proximity, resulting in the formation of a hemin dimer with low peroxidase mimicking activity. The duplex structure was dehybridized in the presence of CAP. The formed hemin monomer featured a strong peroxidase mimicking activity and catalyzed the conversion of non-fluorescent tyramine into fluorescent dityramine by hydrogen peroxide. Fluorescence (with an excitation/emission maxima at 320 and 410 nm, respectively) increased linearly in the 0.1 ng mL-1 to 10 ng mL-1 CAP concentration range. The detection limit based on the 3σ/k criterion reached 0.07 ng mL-1. The proposed assay was successfully employed for CAP detection in (spiked) honey samples with recoveries of 94.3-117.2%. Given its high sensitivity and good stability, this method shows potential in providing a platform for antibiotic detection.

20.
Sci Rep ; 10(1): 15933, 2020 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-32985613

RESUMO

Climate change and rapid urbanization have greatly impacted urban forest ecosystems and the carbon (C) cycle. To assess the effects of urbanization on forest soil C and soil microorganisms, six natural forests in a highly-urbanized region were selected as the research objects. Soil samples were collected to investigate the content and fractions of the soil organic carbon (SOC), as well as the soil microbial community composition. The results showed that the SOC content and fractions were substantially lower in the urban forests than in the suburban forests. Meanwhile, the total amount of phospholipid fatty acids (PLFAs) at suburban sites was twice more than that at urban sites, with shifts in microbial community structure. The potential differences in C inputs and nutrient limitation in urban forests may aggravate the low quantity and quality of SOC and consequently impact microbial community abundance and structure. Variation in microbial community structure was found to explain the loss of soil C pools by affecting the C inputs and promoting the decomposition of SOC. Therefore, the coupled changes in SOC and soil microorganisms induced by urbanization may adversely affect soil C sequestration in subtropical forests.

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