A hybrid polymer protective layer with uniform Li+ flux and self-adaption enabling dendrite-free Li metal anodes.

Lithium (Li) metal is considered as an ideal negative electrode material for next-generation secondary batteries; however, the hideous dendrite growth and parasitic reactions hinder the practical applications of Li metal batteries. Herein, a hybrid polymer film composed of polyvinyl alcohol (PVA) and polyacrylic acid (PAA) is adopted as an artificial protective layer to inhibit the dendritic formation and side reactions in Li metal anodes. PVA with large quantities of polar functional groups can induce even distribution of Li ions (Li+). Alternatively, PAA can in situ react with Li metal to form highly elastic and ionic conducting lithium polyacrylic acid (LiPAA), thereby enabling tight contact and flexible self-adaption with Li metal anodes. Therefore, such a rationally designed functional composite layer, with good binding ability and relatively high Li+ conductivity, as well as excellent capability of homogenizing Li+ flow, accordingly enables Li metal anodes to reveal dendrite-free plating/stripping behaviours and minimum volume variation. As a result, the PVA-PAA modified Li metal anode delivered stable cycling for 700 and 250 h, respectively, at current densities of 1 and 3 mA cm-2 under an areal capacity of 1 mA h cm-2, in a carbonate ester-based electrolyte without any additive, exhibiting boosted cycling and rate performances. The Li anode with a functional PVA-PAA hybrid interlayer can maintain the dense and smooth texture without dendrite formation after long cycles. The full cell of Li|LiFeO4 with our modified Li anode and a cathode with a high areal capacity of 2.45 mA h cm-2 delivers, change to achieved a long-term lifespan of 180 cycles at 1.0 C, with a capacity retention of 96.7%. This work demonstrates a simple and effective strategy of designing multi-functional artificial protective layers, targeting dendrite-free Li anodes.

Performance of HDL-C measurements assessed by a 4-year trueness-based EQA/PT program in China.

OBJECTIVES: A trueness-based EQA/PT program for high density lipoprotein cholesterol (HDL-C) was initiated. We analyzed the 4 year EQA/PT program to overview the measurement standardization for HDL-C in China. METHODS: Two levels of freshly frozen, commutable serum external quality assessment/proficiency testing (EQA/PT) materials were prepared and determined by reference measurement procedure each year. The samples were delivered to clinical laboratories and measured 15 times in 3 days. The precision [coefficient of variation (CV)], trueness (bias), and accuracy [total error (TE)] were calculated and used to evaluate measurement performance. The pass rates of individual laboratories and peer groups were analyzed using the acceptable performance from the National Cholesterol Education Program (NCEP) and biological variation as the evaluation criteria. RESULTS: More than 60% of laboratories use heterogeneous systems, and there was a decrease in the percentage from 2016 to 2019. About 95, 78, and 33% of laboratories met the minimum, desirable and optimum TE criteria derived from biological variation. The pass rates were 87.0% (84.7-88.8%), 58.7% (55.3-62.4%), and 97.3% (95.6-98.3%) that met the acceptable performance of TE, bias, and CV of NCEP. The homogeneous systems had higher pass rates of TE, bias, and CV than the heterogeneous groups in 2016, but they did not show apparent advantages in 2017-2019. CONCLUSIONS: The trueness-based EQA/PT program can be used to evaluate the accuracy, reproducibility, and trueness of results. For some IVD manufacturers and individual laboratories, accuracy, especially trueness, are still problems. Efforts should be made to improve the situation and achieve better HDL-C measurement standardization.

Nonlinear dissipation and nonequilibrium gas flows.

Rayleigh and Onsager showed that in the regime where the flows are small and the thermodynamic forces vary slowly, the entropy generation rate is linearly related to the flows, and the flows are related to the gradient of the forces. Hence, the Rayleigh-Onsager dissipation is only applicable to linear irreversible thermodynamics. We introduce the extension of Rayleigh-Onsager dissipation to highly nonlinear dissipation to treat nonlinear irreversible thermodynamics. This extension fulfills the positive entropy generation criterion. To demonstrate this nonlinear dissipation, we apply it to obtain the generalized hydrodynamics from the kinetic theory according to Eu theory. Specifically, it provides an alternative evolution for a stress tensor and heat flux. The challenging problems of nonlinear irreversible thermodynamics, as represented by nonequilibrium flows, are investigated. The result implies that this study provides a promising alternative to obtain a unified framework for modeling both equilibrium and nonequilibrium gas flows.

Commutability of external quality assessment materials for serum sodium and potassium measurements.

Background The commutability of electrolyte trueness verification materials (ETVs) and commercial general chemistry materials (GCs) was evaluated to investigate their suitability for use in an external quality assessment (EQA) program for serum sodium and potassium measurements. Methods Eighty fresh individual human samples (40 for sodium measurements and 40 for potassium measurements), six ETVs and three GCs were analyzed by five routine methods (validated methods) and by inductively coupled plasma mass spectrometry reference methods (comparative methods) for the determination of sodium and potassium. The commutability was analyzed according to Clinical and Laboratory Standards Institute (CLSI) EP14-A3 protocol and difference in bias approach, respectively. The linearity, bias and imprecision of the routine methods were also assessed according to CLSI guidelines. Results According to EP14-A3 protocol, ETVs were commutable for all assays, and GCs were commutable for 3/5 assays for sodium. ETVs were commutable in most assays except Cobas C501, while GCs showed no commutability except in case of AU5821 for potassium. According to a difference in bias approach, the commutability of ETVs was inconclusive for most routine assays for both sodium and potassium, and GCs were inconclusive for sodium and non-commutable for potassium in most routine assays. The routine methods exhibited excellent linearities and precisions. The majority and minority of relative biases between the routine and reference methods were beyond the bias limits for sodium and potassium, respectively. Conclusions Superiority in the commutability of ETVs over GCs was observed among the sodium and potassium assays whichever evaluation approach was applied.

Serum triglyceride measurements: the commutability of reference materials and the accuracy of results.

Background We aimed to evaluate the commutability of external quality assessment (EQA) materials, aqueous solutions, and commercial reference materials (calibrators and controls), and the accuracy of routine systems for serum triglyceride measurements. Methods According to the clinical and laboratory standards institute (CLSI) EP14-A3 protocol, we analyzed 43 fresh patient specimens and 32 processed materials including lyophilized samples, human serum pools, liquid reagents, swine sera and aqueous solutions by 14 routine methods (evaluated methods) and an isotope dilution liquid chromatography tandem mass spectrometry method (ID-LC/MS/MS) (comparative method). The accuracy of the routine method was evaluated by analyzing the absolute bias, relative bias, and the bias at three medical decision levels based on CLSI EP9-A3. Results Frozen serum samples and swine sera were commutable for all of the assays. The EQA/PT materials, commercial calibrators and control materials showed matrix effects differently on routine methods. The aqueous glycerol solutions were generally noncommutable for routine method. All except one routine analytical systems met the National Cholesterol Education Program (NCEP) recommended analytical performance guideline analytical quality criteria for total error. Conclusions Matrix effects and calibration biases existed in measurements of serum triglyceride. Continued efforts are needed to improve the accuracy and comparability of routine measurements.

A candidate reference method for serum calcium measurement by inductively coupled plasma mass spectrometry.

BACKGROUND: Calcium is an important serum ion which is frequently assayed in clinical laboratories. Since quality assurance requires reference methods, the establishment of a candidate reference method for serum calcium measurement is important. METHOD: An inductively coupled plasma mass spectrometry (ICP-MS) method was developed. Serum samples were spiked gravimetrically with aluminum internal standard, digested with 69% ultrapure nitric acid and diluted to test concentration. Then the (44)Ca/(27)Al ratios were measured by ICP-MS in hydrogen mode. The method was calibrated using 5% nitric acid matrix calibrators and the calibration function was established with bracketing method. RESULTS: The correlation coefficients between the measured (44)Ca/(27)Al ratios and the analyte concentrations ratios were all >0.9999. The coefficients of variation of the measurements were 0.27% and 0.16% for two spiked serum. The analytical recovery was 100.24%. The accuracy of the measurement was also verified through measurement of certified reference materials. Comparison with recognized reference method and international inter-laboratory comparisons gave satisfied results. CONCLUSION: New ICP-MS method is specific, precise, simple, and low in cost, and may be used as a candidate reference method in the standardization of serum calcium measurement.

Quantification of hemoglobin A1c by off-line HPLC separation and liquid chromatography-tandem mass spectrometry: a modification of the IFCC reference measurement procedure.

BACKGROUND: The quality of hemoglobin A1c measurement is very important in the management of diabetes. A reference system has been established by the IFCC Working Group on HbA1c Standardization. We did some modification of the IFCC Reference Measurement Procedure with MS detection which significantly decreased the analysis time and improved the precision of the analytes by off-line HPLC separation and liquid chromatography-tandem mass spectrometry (LC/MS/MS) analysis. METHODS: The samples were prepared and enzymatically cleaved according to the IFCC HbA1c reference measurement procedure. Then the digest solution was injected to a reversed phase HPLC for purification and a clean fraction was collected. The fraction was analyzed by liquid chromatography-tandem mass spectrometry with an isocratic elution on a C18 column. Liner regression was used to determine the concentration of HbA1c. RESULTS: The total analysis time which includes the off-line HPLC separation and the LC/MS/MS analysis was reduced by at least 65% compared to the existing IFCC method. The transitions of m/z 348.4→237.2 and m/z 429.4→245.2 were selected for quantification of non-glycated and glycated hexapeptide. Fifty seven hemolysate samples used in recent 3-years' IFCC HbA1c inter-laboratory studies (2012-2014) were analyzed by the LC/MS/MS procedure for method validation. The CVS were between 0.16% and 1.87% for 4 measurements per sample in the concentration range for HbA1c between 30.4 and 145.8 mmol/mol. The relative bias of the LC/MS/MS method was varied from -3.21% to 2.47% compared to the IFCC network assigned values. CONCLUSIONS: This method is an efficient and reliable procedure for the determination of HbA1c. After thorough evaluation within the IFCC Network this modification may be implemented in the IFCC RMP for HbA1c with MS detection.