Trace Rare Earth Element Detection in Food and Agricultural Products Based on Flow Injection Walnut Shell Packed Microcolumn Preconcentration Coupled with Inductively Coupled Plasma Mass Spectrometry

With the extensive use of rare earth elements (REEs) in agriculture as fertilizer and feed additives, the concentration of REEs has increased in environmental and biological samples and finally impaired human health by food chain accumulation. The determination of trace REEs has gained considerable importance because of their toxicity and increasing occurrence. In this work, walnut shell has been used as the green adsorbent in online preconcentration and detection of REEs in food and agricultural products coupled with inductively coupled plasma mass spectrometry (ICP-MS). Because of the porous surface and abundant −COO^– groups on the walnut shell surface, the walnut shell-packed microcolumn provides high adsorption efficiency and high tolerable capacity for coexisting ions. Under the optimized conditions, the adsorption efficiency of the walnut shell packed microcolumn was as high as 98.9% for 15 REEs, and the tolerable concentration ratios were between 2000 and 80 000 000 for 37 kinds of coexisting interfering ions. The enhancement factors achieved were 79–102 for 15 REEs with a sample loading volume of 4.7 mL. The detection limits were in the range of 2–34 pg g^–1. The relative standard deviation for 11 replicate preconcentrations of 2.5 ng L^–1 REEs solution ranged from 0.5 to 2.0%. The present method was successfully applied to selective determination of REEs in 4 environmental and biological certified reference materials and 18 locally collected food and agricultural products

Lewis acid-catalyzed asymmetric synthesis of complex chiral-fluorinated aminoesters via addition of acyclic silyl dienolates to α-fluoroalkyl sulfinylimines

<p>A Lewis acid-catalyzed asymmetric addition reaction of β-methyl- or γ-methyl-substituted acyclic silyl dienolates <b>2</b> with α-fluoroalkylsulfinylimines <b>1</b> furnished complex fluorinated aminoesters in high yield under stereocontrol. Two different transition states were proposed to explain the observed selectivity.</p

Evaluative criteria for sleepwear: A study of privately consumed product in the People’s Republic of China

The purpose of this study is to explore and investigate Chinese male consumers’ perceptions and behaviours towards low involvement and privately consumed product – pyjamas. According to our literature review, little research has been devoted to this particular topic. In this study, multiple product cues were used to measure and uncover what constitute consumers’ evaluation and purchase decisions. The questionnaire survey for this study was conducted in a second-tier city by using the convenience sampling method. In total, 256 useable questionnaires were collected and analysed. This study shows evidence that a majority of the Chinese male respondents did not wear pyjamas for sleeping. The intrinsic cues of sleepwear were ranked relatively higher than extrinsic cues, and the comfort cue was the most important criterion for product evaluation. Further research on this topic focusing on different products, samples and cities are recommended. The findings of this study provide insight and implications for fashion practitioners to develop their product and business in China.</p

AgBF₄ catalyzed regio- and stereoselective synthesis of <i>trans</i> α-vinyl-β-amino esters via asymmetric addition of siyl dienolate to sulfinylimines

<p>AgBF₄ catalyzed Mannich-type reactions of siyl dienolate with chiral aryl-substituted (<i>S</i>)-<i>N</i>-<i>tert</i>-butanesulfinylimines has been developed. A class of chiral <i>trans</i> α-vinyl-β-amino esters was obtained in moderate to excellent yields (up to 93%), good diastereoselectiveties (up to 92:8 dr), and complete α-site regioselectivity.</p

Synthesis of 2‑Amino-3-hydroxy‑3<i>H</i>‑indoles via Palladium-Catalyzed One-Pot Reaction of Isonitriles, Oxygen, and <i>N</i>‑Tosylhydrazones Derived from 2‑Acylanilines

A cyanide-free one-pot procedure was developed to access 2-amino-3-hydroxy-3<i>H</i>-indoles, which involved: (1) <i>in situ</i> formation of ketenimines by the reaction of <i>N</i>′-(1-(2-amino­phenyl)­ethylidene)-<i>p</i>-tosyl­hydrazones with isonitriles; (2) the intramolecular nucleophilic attack of ketenimines by the amino in phenyl furnishing the ring closure leading to 2-aminoindoles; (3) the oxidation of 2-aminoindoles by O₂ leading to 2-amino-3-hydroxy-3<i>H</i>-indoles. This strategy represents not only a key compliment to the sporadic synthetic methods toward 2-amino-3-hydroxy-3<i>H</i>-indoles but also progress in <i>N-</i>tosylhydrazone, isonitrile, and ketenimine chemistry

Synthesis of 2‑Amino-3-hydroxy‑3<i>H</i>‑indoles via Palladium-Catalyzed One-Pot Reaction of Isonitriles, Oxygen, and <i>N</i>‑Tosylhydrazones Derived from 2‑Acylanilines

A cyanide-free one-pot procedure was developed to access 2-amino-3-hydroxy-3<i>H</i>-indoles, which involved: (1) <i>in situ</i> formation of ketenimines by the reaction of <i>N</i>′-(1-(2-amino­phenyl)­ethylidene)-<i>p</i>-tosyl­hydrazones with isonitriles; (2) the intramolecular nucleophilic attack of ketenimines by the amino in phenyl furnishing the ring closure leading to 2-aminoindoles; (3) the oxidation of 2-aminoindoles by O₂ leading to 2-amino-3-hydroxy-3<i>H</i>-indoles. This strategy represents not only a key compliment to the sporadic synthetic methods toward 2-amino-3-hydroxy-3<i>H</i>-indoles but also progress in <i>N-</i>tosylhydrazone, isonitrile, and ketenimine chemistry

Trichloroethylene-Induced Gene Expression and DNA Methylation Changes in B6C3F1 Mouse Liver

<div><p>Trichloroethylene (TCE), widely used as an organic solvent in the industry, is a common contaminant in air, soil, and water. Chronic TCE exposure induced hepatocellular carcinoma in mice, and occupational exposure in humans was suggested to be associated with liver cancer. To understand the role of non-genotoxic mechanism(s) for TCE action, we examined the gene expression and DNA methylation changes in the liver of B6C3F1 mice orally administered with TCE (0, 100, 500 and 1000 mg/kg b.w. per day) for 5 days. After 5 days TCE treatment at a dose level of 1000 mg/kg b.w., a total of 431 differentially expressed genes were identified in mouse liver by microarray, of which 291 were up-regulated and 140 down-regulated. The expression changed genes were involved in key signal pathways including PPAR, proliferation, apoptosis and homologous recombination. Notably, the expression level of a number of vital genes involved in the regulation of DNA methylation, such as Utrf1, Tet2, DNMT1, DNMT3a and DNMT3b, were dysregulated. Although global DNA methylation change was not detected in the liver of mice exposed to TCE, the promoter regions of Cdkn1a and Ihh were found to be hypo- and hypermethylated respectively, which correlated negatively with their mRNA expression changes. Furthermore, the gene expression and DNA methylation changes induced by TCE were dose dependent. The overall data indicate that TCE exposure leads to aberrant DNA methylation changes, which might alter the expression of genes involved in the TCE-induced liver tumorgenesis.</p></div

Cs₂CO₃‑Promoted Carboxylation of <i>N</i>‑Tosylhydrazones with Carbon Dioxide toward α‑Arylacrylic Acids

A Cs₂CO₃-promoted carboxylation of <i>N</i>-tosylhydrazones and CO₂ has been developed. The reaction proceeded efficiently at 80 °C under atmospheric CO₂, gave the corresponding α-arylacrylic acids in moderate to good yields. This method was featured with (1) the employment of Cs₂CO₃ rather than ^<i>n</i>BuLi as the base; (2) a reaction temperature of 80 °C rather than −78 °C

TBAI-Catalyzed Reaction between <i>N</i>‑Tosylhydrazones and Sulfur: A Procedure toward 1,2,3-Thiadiazole

A TBAI-catalyzed reaction between <i>N</i>-tosyl hydrazone and sulfur was developed, leading to 1,2,3-thiadiazoles in moderate to good yields. It represents a facile and practical procedure to access thiadiazole under metal-free conditions. This procedure serves as an improvement for the Hurd–Mori reaction

Vibration interference in SIM imaging of LIPSS in experiments without antivibration

Vibration interference in SIM imaging of LIPSS in experiments without antivibratio