Shell Modulation of Hollow Metal Sulfide Nanocomposite for Stable Potassium Storage at Room and High Temperature.

The large size of K-ion makes the pursuit of stable high-capacity anodes for K-ion batteries (KIBs) a formidable challenge, particularly for high temperature KIBs as the electrode instability becomes more aggravated with temperature climbing. Herein, we demonstrate that a hollow ZnS@C nanocomposite (h-ZnS@C) with a precise shell modulation can resist electrode disintegration to enable stable high-capacity potassium storage at room and high temperature. Based on a model electrode, we identify an interesting structure-function correlation of the h-ZnS@C: with an increase in the shell thickness, the cyclability increases while the rate and capacity decrease, shedding light on the design of high-performance h-ZnS@C anodes via engineering the shell thickness. Typically, the h-ZnS@C anode with a shell thickness of 60 nm can deliver an impressive comprehensive performance at room temperature; the h-ZnS@C with shell thickness increasing to 75 nm can achieve an extraordinary stability (88.6 % capacity retention over 450 cycles) with a high capacity (450 mAh g-1) and a superb rate even at an extreme temperature of 60 °C, which is much superior than those reported anodes. This contribution envisions new perspectives on rational design of functional metal sulfides composite toward high-performance KIBs with insights into the significant structure-function correlation.

[Effect of Lactobacillus coryniformis FZU63 on the flavor quality of black tea beverage].

The tea beverages will be endowed with distinct aroma and taste, as well as various biologically active compounds including probiotic factors, when fermented with lactic acid bacteria (LAB). However, at present, few studies on the dynamics of flavors in tea soup at different fermentation stages were conducted. In this study, the composition of monosaccharides, aromatic components, free amino acids, and organic acids were measured, when the black tea beverages were fermented with Lactobacillus coryniformis FZU63 which was isolated from Chinese traditional kimchi. The results indicated that monosaccharides including glucose, fructose, mannose and xylose in black tea beverages are the main carbon sources for fermentation. In addition, the abundance of aromatic compounds in black tea soup are increased significantly at different fermentation stages, which endow the fermented black tea soup with fruit aroma on the basis of flowery and nutty aroma. Moreover, some bitter amino acids are reduced, whereas the content of sweet and tasty amino acids is elevated. Furthermore, the levels of lactic acid, malic acid, citric acid and other organic acids are accumulated during the fermentation. Additionally, sensory evaluation displays that black tea beverage is acquired with comprehensive high-quality after being fermented for 48 h. This study provides a theoretical basis to steer and control the flavor formation and quality of the fermented tea beverages during LAB fermentation.

Headspace solid-phase microextraction with on-fiber derivatization for the determination of aldehydes in algae by gas chromatography-mass spectrometry.

A simple, fast, sensitive and cost-effective method based on headspace solid-phase microextraction (HS-SPME) with on-fiber derivatization coupled with gas chromatography-mass spectrometry was developed for the determination of six typical aldehydes, 2E-hexenal, heptanal, 2E-heptenal, 2E,4E-heptadienal, 2E-decenal and 2E,4E-decadienal in laboratory algae cultures. As derivatization reagent, O-2,3,4,5,6-(pentafluorobenzyl) hydroxylamine hydrochloride, was loaded onto the poly(dimethylsiloxane)/divinylbenzene fiber for aldehydes on-fiber derivatization prior to HS-SPME. Various influence factors of extraction efficiency were systematically investigated. Under optimized extraction conditions, excellent method performances for all the six aldehydes were attained, such as satisfactory extraction recoveries ranging from 67.1 to 117%, with the precision (relative standard deviation) within 5.3-11.1%, and low detection limits in the range of 0.026-0.044 µg/L. The validated method was successfully applied for the analysis of the aldehydes in two diatoms (Skeletonema costatum and Chaetoceros muelleri), two pyrrophytas (Prorocentrum micans and Scrippsiella trochoidea) and Calanus sinicus eggs (feeding on the two diatoms above).

Determination of 16 polycyclic aromatic hydrocarbons in environmental water samples by solid-phase extraction using multi-walled carbon nanotubes as adsorbent coupled with gas chromatography-mass spectrometry.

A solid-phase extraction (SPE) using multi-walled carbon nanotubes (MWCNTs) as adsorbent coupled with gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. Several condition parameters, such as extraction adsorbents, elution solvents and volumes, and sample loading flow rate and volume were optimized to obtain high SPE recoveries and extraction efficiency. 150mg MWCNTs as sorbent presented high extraction efficiency of 16 PAHs due to the large specific surface area and high adsorption capacity of MWCNTs compared with the commercial C18 column (250mg/2mL). The calibration curves of 16 PAHs extracted were linear in the range of 20-5000ngL(-1), with the correlation coefficients (r(2)) between 0.9848 and 0.9991. The method attained good precisions (relative standard deviation, RSD) from 1.2% to 12.1% for standard PAHs aqueous solutions; method recoveries ranged in 76.0-125.5%, 74.5-127.0%, and 70.0-122.0% for real spiked samples from river water, tap water and seawater, respectively. Limits of detection (LODs, S/N=3) of the method were determined from 2.0 to 8.5ngL(-1). The optimized method was successfully applied to the determination of 16 PAHs in real environmental water samples.

Determination of organophosphorus pesticides in underground water by SPE-GC-MS.

A rapid and effective method is developed for the determination of organophosphorus pesticides (dichlorovos, methyl parathion, malathion, and parathion) in underground water by solid-phase extraction (SPE)-gas chromatography-mass spectrometry. Some important extraction parameters including types of SPE adsorbents, elution solvents, and injection volume of water samples are optimized. The use of Cleanert-PEP polymer SPE column improved higher extraction efficiencies than the C18 SPE column commonly used. Water samples are extracted using Cleanert-PEP as SPE adsorbent and ethyl acetate as elution solvent. Precision values expressed as relative standard deviation for 1 microg/L of spiked water sample are in the range of 1.6-4.0%. Dichlorvos, methyl parathion, malathion, and parathion are linear in the range of 0.1-1.0 microg/L (r2=0.9976), 0.1-2.0 microg/L (r2=0.9883), 0.1-2.0 microg/L (r2=0.9798), and 0.055-1.1 microg/L (r2=0.9790), respectively. The limits of detection for spiked water samples are in the range of 4-10 ng/L. The optimized method is applied to the determination of underground water samples. Recoveries are between 59.5% and 94.6% for spiked underground water samples. The benefit of the method developed is rapid, simple, and has good repeatability.