Soft lithography using acryloxy perfluoropolyether composite stamps

This paper describes composite patterning elements that use a commercially available acryloxy perfluoropolyether (a-PFPE) in various soft lithographic techniques, including microcontact printing, nanotransfer printing, phase-shift optical lithography, proximity field nanopatterning, molecular scale soft nanoimprinting, and solvent assisted micromolding. The a-PFPE material, which is similar to a methacryloxy PFPE (PFPE-DMA) reported recently, offers a combination of high modulus (10.5 MPa), low surface energy (18.5 mNm(-1)), chemical inertness, and resistance to solvent induced swelling that make it useful for producing high fidelity patterns with these soft lithographic methods. The results are comparable to, and in some cases even better than, those obtained with the more widely explored material, high modulus poly(dimethylsiloxane) (h-PDMS).     

The performance of nu-support vector regression on determination of soluble solids content of apple by acousto-optic tunable filter near-infrared spectroscopy

The ν-support vector regression (ν-SVR) was used to construct the calibration model between soluble solids content (SSC) of apples and acousto-optic tunable filter near-infrared (AOTF-NIR) spectra. The performance of ν-SVR was compared with the partial least square regression (PLSR) and the back-propagation artificial neural networks (BP-ANN). The influence of SVR parameters on the predictive ability of model was investigated. The results indicated that the parameter ν had a rather wide optimal area (between 0.35 and 1 for the apple data). Therefore, we could determine the value of ν beforehand and focus on the selection of other SVR parameters. For analyzing SSC of apple, ν-SVR was superior to PLSR and BP-ANN, especially in the case of fewer samples and treating the noise polluted spectra. Proper spectra pretreatment methods, such as scaling, mean center, standard normal variate (SNV) and the wavelength selection methods (stepwise multiple linear regression and genetic algorithm with PLS as its objective function), could improve the quality of ν-SVR model greatly.     

Simultaneous determination of 15 flavonoids in Epimedium using pressurized liquid extraction and high-performance liquid chromatography

Herba Epimedii (family Berberidaceae), Yinyanghuo in Chinese, is one of the commonly used Chinese medicines. Flavonoids are considered as its active components. In this study, a reliable pressurized liquid extraction (PLE) and HPLC method was developed for simultaneous determination of 15 flavonoids, namely hexandraside E, kaempferol-3-O-rhamnoside, hexandraside F, epimedin A, epimedin B, epimedin C, icariin, epimedoside C, baohuoside II, caohuoside C, baohuoside VII, sagittatoside A, sagittatoside B, 2'-O-rhamnosyl icariside II and baohuoside I in different species of Epimedium. The analysis was performed by using a Zorbax SB-C18 analytical column (250 mm x 4.6 mm I.D., 5 microm) at gradient elution of water and acetonitrile with diode-array detection (270 nm). All calibration curves showed good linearity (r(2)>0.9997) within test ranges. The LOD and LOQ were lower than 1.31 ng and 2.62 ng on column, respectively. The RSD for intra- and inter-day of 15 analytes was less than 3.8% at three levels, and the recoveries were 90.5-106.8%. The validated method was successfully applied for the analysis of 15 flavonoids in different species of Epimedium which had great variation on the contents of investigated flavonoids. Hierarchical clustering analysis based on the characteristics of 15 investigated compound peaks in HPLC profiles showed that 26 samples were divided into three main clusters, which were in accordance with their flavonoid contents. Four flavonoids including epimedin A, B, C and icariin were optimized as markers for quality control of the species of Epimedium used as Yinyanghuo.     

Selective and Sensitive Determination of Paracetamol and Levodopa with Using Electropolymerized 3,5-Diamino-1,2,4-triazole Film on Glassy Carbon Electrode

For determination of levodopa (L-DOPA) and paracetamol (PAR), selective, effective and sensitive electrochemical sensor based on 3,5-diamino-1,2,4-triazole (35DT) on glassy carbon (GC) electrode was reported. The DPV method was used to obtain the oxidation peak current of L-DOPA which increased linearly with its concentration at the range of 1–99 μM and 99–480 μM. The linear relationship between the concentration of PAR and its peak current was obtained in the range of 0.3–55 μM and 55–475 μM. The limit of detection values for PAR and L-DOPA were found to be 0.1 and 0.25 μM, respectively. Satisfactory results were obtained in pharmaceutical samples.     

A molecular docking simulation study on potent inhibitors against Rhizoctonia solani and Magnaporthe oryzae in rice: silver-tetrylene and bis-silver-tetrylene complexes vs. validamycin and tricyclazole pesticides

Structural Chemistry - Rice, well known as the most important staple food source worldwide, is highly susceptible to many infectious diseases, especially rice sheath blight caused by fungus...     

A self-assembled supramolecular organic material for selective extraction of uranium from aqueous solution

Journal of Radioanalytical and Nuclear Chemistry - A supramolecular organic material MA-IPA containing melamine and isophthalic acid was prepared by low-temperature hydrothermal reaction, with an...     

Efficient N-heterocyclic carbene nickel pincer complexes catalyzed cross coupling of benzylic ammonium salts with boronic acids

Pyridine-bridged bis-benzimidazolylidene nickel complexes exhibited very high catalytic activity toward cross coupling of inactive (hetero)aryl benzylic ammonium salts with (hetero)aryl and alkenyl boronic acids under mild reaction conditions. Even at 2 mol% catalyst loading, a wide range of substrates for both coupling partners with different steric and electronic properties were well tolerated.     

Enhanced and tunable oxygen carrier and amperometric sensor based on a glassy carbon electrode assembly of a hemoglobin-chitosan-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> composite

The authors have prepared organized assemblies of a hemoglobin-chitosan(CS)@Fe₃O₄ composite on glassy carbon electrodes (GCEs) via three strategies with the aim of preparing tunable Hb-coated GCEs with good stability and long-term oxygen storage capability. The formation and morphology of the Hb-CS@Fe₃O₄ composite was characterized by scanning electrochemical microscopy, XRD and UV–vis spectroscopy. It is shown that Hb is fully integrated into the CS@Fe₃O₄ and can be manipulated by a magnetic field whilst maintaining its biological activity. In the absence of oxygen, a surface-controlled electrode process occurs with an interfacial electron transfer rate (k _s) of 2.14 s^?1. The modified GCE also has a favorable oxygen storage lifetime (almost 6 h). One Hb-CS@Fe₃O₄ film on the electrode displays particularly good electrocatalytic reduction activity towards oxygen. The linear range for detection of O₂ is 1.2?×?10^?7?~?2.0?×?10^?4 mol L^?1 with a detection limit of 4.0?×?10^?8 mol L^?1. In our opinion, this method has great potential in terms of enhanced oxygen storage capability of Hb, which can be applied in special situations such as space operations, down hole mining, mountaineering and diving.

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Graphical Abstract Hb-CS@Fe₃O₄ composites were prepared by three strategies, and oxygen carrying capability was studied. The corresponding modified electrode constructed on the basis of the magnetic field environment was superior in terms of stability, sensitivity and O₂ storage time, showing wider linear range and lower detection limit.