Recently, much attention has been devoted to food-related health issues. In particular, food-poisoning bacteria are becoming a serious threat to human health. So far, techniques used to detect these bacteria are time-consuming and laborious. To overcome these challenges, a biosensor with a simple platform was developed to detectSalmonella typhimurium. The colorimetric strategy is attractive because it enables simple and rapid sensing with the naked eyes. We used magnetic nanoparticles (MNPs), specific aptamers, and a colorimetric substrate, 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. Because MNPs display enzyme-like activities, they can undergo color changes with the help of a colorimetric substrate. In this system, MNPs were first incubated with aptamers that specifically interact with theSalmonellaspecies, reducing the peroxidase activity of the MNPs via DNA-mediated shielding of catalytic activity. After the addition ofSalmonellacells to the solution, specific aptamers on the MNPs interact with theSalmonella, consequently enhancing the peroxidase activity of the MNPs. Considering their low cost, easy separation, and stable activity, MNPs could be applied to various detection systems.

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BACKGROUND/OBJECTIVESRelocation to new environments can have a negative impact on health by altering body weight and dietary patterns. This study attempted to elucidate changes in body weight, food security, and their current food and nutrient consumption in adult North Korean refugees (NKR) living in South Korea (SK).SUBJECTS/METHODSThis study analyzed data on 149 adult NKR from a North Korean refugee health in SK cohort at four time points (leaving North Korea, entering SK, first examination, and second examination). Body weight was self-reported at the two earlier time points and directly measured at the two later time points. Food security, diet-related behaviors (dietary habits and food consumption), and sociodemographic information were obtained using a self-administered questionnaire. Nutrient intake information was obtained by one-day 24-hour recall. Statistical analyses were performed with SPSS ver 23.0.RESULTSBody weight increased during relocation by an average of 4 kg, although diversified patterns were observed during the settlement period in SK. Approximately 39.6% of subjects maintained their body weight between the first and second examinations, whereas 38.6% gained and 22.1% lost at least 3% of their body weight at the first examination by the second examination. Food security status improved from 12.1% food secure proportion to 61.7%. NKR showed generally good food and nutrient consumption (index of nutrient quality: 0.77–1.93). The body weight loss group showed the most irregular meal consumption pattern (P < 0.05), and eating-out was infrequent in all three groups. Consumption frequencies of food groups did not differ by group, except in the fish group (P = 0.036).CONCLUSIONThis study observed considerable body weight adjustment during the settlement period in SK after initial weight gain, whereas food security consistently improved. More detailed understanding of this process is needed to assist healthy settlement for NKR in SK.

A new nickel(II) porphyrin complex, [Ni (porp)] (1), has been synthesized and characterized by H NMR, C NMR and mass spectrometry analysis. This Ni porphyrin complex 1 quantitatively catalyzed the epoxidation reaction of a wide range of olefins with meta-chloroperoxybenzoic acid (m-CPBA) under mild conditions. Reactivity and Hammett studies, H O-exchange experiments, and the use of PPAA (peroxyphenylacetic acid) as a mechanistic probe suggested that participation of multiple active oxidants Ni -OOC(O)R 2, Ni -Oxo 3, and Ni -Oxo 4 within olefin epoxidation reactions by the nickel porphyrin complex is markedly affected by solvent polarity, concentration, and type of substrate. In aprotic solvent systems, such as toluene, CH Cl , and CH CN, multiple oxidants, Ni -(O)R 2, Ni -Oxo 3, and Ni -Oxo 4, operate simultaneously as the key active intermediates responsible for epoxidation reactions of easy-to-oxidize substrate cyclohexene, whereas Ni -Oxo 3 and Ni -Oxo 4 species become the common reactive oxidant for the difficult-to-oxidize substrate 1-octene. In a protic solvent system, a mixture of CH CN and H O (95:5), the Ni -OOC(O)R 2 undergoes heterolytic or homolytic O-O bond cleavage to afford Ni -Oxo 3 and Ni -Oxo 4 species by general acid catalysis prior to direct interaction between 2 and olefin, regardless of the type of substrate. In this case, only Ni -Oxo 3 and Ni -Oxo 4 species were the common reactive oxidant responsible for olefin epoxidation reactions.

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High‐valent metal‐oxo species are key intermediates for the oxygen atom transfer step in the catalytic cycles of many metalloenzymes. While the redox‐active metal centers of such enzymes are typically supported by anionic amino acid side chains or porphyrin rings, peptide backbones might function as strong electron‐donating ligands to stabilize high oxidation states. To test the feasibility of this idea in synthetic settings, we have prepared a nickel(II) complex of new amido multidentate ligand. The mononuclear nickel complex of this N5 ligand catalyzes epoxidation reactions of a wide range of olefins by using mCPBA as a terminal oxidant. Notably, a remarkably high catalytic efficiency and selectivity were observed for terminal olefin substrates. We found that protonation of the secondary coordination sphere serves as the entry point to the catalytic cycle, in which high‐valent nickel species is subsequently formed to carry out oxo‐transfer reactions. A conceptually parallel process might allow metalloenzymes to control the catalytic cycle in the primary coordination sphere by using proton switch in the secondary coordination sphere.

A hybrid composite of Au/GO was synthesized and its capability as a PCR enhancer was demonstrated.

A new fluorescent sensor 1, containing furan and julolidine moieties linked through a Schiff-base, has been synthesized. Distinct "turn-on" fluorescence enhancement of 1 was observed upon the addition of F in a near-perfect aqueous solution. The binding capabilities of 1 with F were studied by using fluorescent spectroscopic techniques, ESI-mass analysis and NMR titration measurements. The detection limit for the analysis of F was found to be 10.02 μM, which is below the WHO guideline (79 μM) for drinking water. Practically, the sensing ability of 1 for F was successfully applied in real water samples. The sensing mechanism for F was proposed to be the ICT mechanism via the hydrogen bonding, which was well explained by theoretical calculations.