Main text The CCQM-K154.c comparison was coordinated by the the Bureau International des Poids et Mesures (BIPM) and the Chinese National Institute of Metrology (NIM) on behalf of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) for National Measurement Institutes (NMIs) and Designated Institutes (DIs) which provide measurement services in organic analysis under the 'Comité International des Poids et Mesures' Mutual Recognition Arrangement (CIPM MRA) and/or have participated in the BIPM's Mycotoxin Metrology Capacity Building and Knowledge Transfer (MMCBKT) project as part of its "Metrology for Safe Food and Feed in Developing Economies" Capacity Building Programme. Gravimetrically-prepared solutions having an assigned mass fraction of specified organic analytes are routinely used to calibrate measurement processes for the quantification of the same analytes in matrix samples. Appropriate assignments of the property value and associated uncertainty of calibration solutions thus underpin the traceability of routine analysis and are critical for accurate measurements. Evidence of successful participation in relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes and designated institutes. In total, nine NMIs/DIs participated in the Track C, Model II, Key Comparison CCQM-K154.c [Gravimetric preparation and value assignment of deoxynivalenol (DON) in acetonitrile (ACN)] for emerging areas of global interest and innovation. Participants were requested to gravimetrically prepare calibration solutions and value assign the mass fractions, expressed in mg/kg, of deoxynivalenol (DON) in the acetonitrile (ACN) solution. Study samples, with assigned values and associated uncertainties were prepared by the comparison participants and sent to the coordinating laboratory for comparison. The Key Comparison Reference Values (KCRVs), calculated from values measured by the coordinating laboratory based on calibrations obtained from independent gravimetrically prepared calibrant solutions, agreed with participants reported values, within their stated uncertainties. DON belongs to the large group of trichothecene mycotoxins. It is produced by certain fungi of the genus Fusarium that predominantly infect wheat, corn, oats, barley, rice, and other grains in the field or during storage. It was anticipated to provide a challenge representative for the gravimetrical preparation and value assignment of calibration solutions in the mass fraction range of 10 mg/kg to 100 mg/kg of mycotoxins with broadly similar structural characteristics. Ten participants of the MMCBKT programme were provided with a stock solution having a known DON mass fraction and expanded uncertainty to use to gravimetrically prepare and value assign a calibration solution. Three NMIs/DIs also participated using their own calibration solutions. The use of in-house solutions required an additional capacity to undertake a fit-for-purpose purity assessment. NIM was the only NMI participating using both the MMCBKT based and their own in-house assigned solutions in order to connect the two different groups. It was decided to propose separate KCRVs for each of the two ampoules provided by the participating NMIs/DIs based on the DON mass fraction. This allowed participants to demonstrate the efficacy of their implementation of the approaches used to gravimetrically prepare calibration solutions and to assess the DON mass fraction. The majority of the DON mass fraction KCRVs ( w KCRV ) for CCQM-K154.c spanned a mass fraction range of 9.88 mg/kg to 123.45 mg/kg. The relative expanded uncertainties U( w KCRV ) ranged from 2.8 % to 6.8 %. Inspection of the degree of equivalence plots for the DON mass fraction assignments in CCQM-K154.c indicated that there was an excellent agreement of results. To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/ . The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
To develop and confirm an individualized predictive model to ascertain the probability of deep venous thrombosis in patients with acute poisoning after undergoing hemoperfusion.Three hundred eleven patients with acute poisoning who were admitted to a hospital in China between October 2017 and February 2019 were included in the development group. Eighty patients with acute poisoning who were admitted between February and May 2019 were included in the validation group. The independent risk factors for deep venous thrombosis were examined. An individualized predictive model was developed using regression coefficients.The number of catheter indwelling days, having a catheter while being transported, elevated serum homocysteine concentrations, and dyslipidemia were independent risk factors for deep venous thrombosis following hemoperfusion in patients with acute poisoning. The areas under the receiver operating characteristic curve of the development and validation groups were 0.713 and 0.702, respectively, which suggested that the prediction model had good discrimination capacity. The calibration belts of the two groups were ideal.Our prediction model has a moderate predictive effect for the occurrence of deep venous thrombosis in patients with acute poisoning. In clinical practice, this model could be combined with a common thrombosis risk assessment model.
This study presents the development and validation of a fast and high throughput method based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique followed by gas chromatography quadrupole time-of-flight mass spectrometry (GC-QTOF/MS) for the simultaneous determination of 21 organophosphorus flame retardants (OPFRs) in rice samples. The factors that impact sample pretreatment and GC-QTOF/MS were optimized and isotope dilution mass spectrometry (IDMS) was established for accurate quantification. The recoveries of OPFRs were in the ranges of 82.3%-110.4% and the relative expanded uncertainties ranged from 1.52% to 11.98%. The limit of quantification (LOQ) ranged from 0.05 ng/g to 1.07 ng/g, which is lower than or comparable to that reported in previous works. The developed method was successfully applied to the analysis of real rice samples and 14 OPFRs were detected, with contents ranging from 0.05 ng/g to 10.43 ng/g.
Due to inconsistent objectives and asymmetric information, serious principal-agent problems often occur between private business owners and their professional managers. The first problem of the principal-agent problem in private businesses is monitoring, i.e., the problem of asymmetric information, while the second probelem is the incentive-constraint problem based on the monitoring. Only effective monitoring can well evaluate the contribution of professional managers, which can more effectively motivate professional managers.
In this study, a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method was developed for simultaneous determination of 30 legacy and emerging per- and polyfluoroalkyl substances (PFASs) in fish by UHPLC-MS/MS.
To investigate the influences and mechanism of erythropoietin (EPO) on the cognitive function of vascular dementia (VD) rats.1) Spatial memory capacity was assessed by Morris water maze test; 2) Pathological conditions of brain tissues were detected by hematoxylin-eosin (HE) staining; 3) The effect of treatment on apoptosis was observed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining; 4) Western blotting was used to examine the protein expression in hippocampal neurons.The escape latency and swimming distance in the EPO group were much shorter than those in the Model group on the fifth day. In the spatial exploration test, the time spent in the target quadrant was longer, the number of platform crossings was larger and the swimming speed was higher in the Sham group and EPO group than those in the Model group. The results of HE staining showed that the cells in the hippocampal CA1 region were arranged closely in the Sham group, loosely and disorderly in the Model group but significantly better in the EPO group. Compared with that in the Model group, the number of apoptotic cells in the EPO group was obviously smaller. The results of Western blotting revealed that the expressions of EPO, p-EPOR, p-SHP2, p-TrKB, p-PI3K, p-ERK1/2 and Bcl-2 rose, while the expressions of P22, P47, Caspase-3, Caspase-9 and Bax significantly declined in the EPO group.EPO can effectively ameliorate the cognitive dysfunction induced by chronic hypoperfusion in VD rats by mediating oxidative stress-related pathways.
Because current protection is simple,economic and reliable,it is widely used in power system.However,the concept of current protection is still abstract and hard to understand for students who are beginners of relay protection curriculum.In order to facilitate understanding of the related principle of the current protection for students,and carry out current protection experiments,simulation experimental software has been designed for current protection.Students can complete the stage current protection (no direction/ direction),zero sequence current protection (no direction/ direction) experiments by the software.The experimental software includes fault simulation and trip simulation of current protection.The function of fault simulation is completed by DDRTS.VB is adopted as the developing tool of current protection trip simulation.
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