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41.
Physico-chemical properties investigation of softwood surface after treatment with organic anhydride
Ruxanda Bodîrlău Carmen-Alice Teacă Dan Roşu Liliana Roşu Cristian-Dragoş Varganici Adina Coroabǎ 《Central European Journal of Chemistry》2013,11(12):2098-2106
Wood originating from a softwood species was subjected to chemical treatment by reaction with succinic anhydride in N, N-dimethylformamide at different concentration values. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis were used to study changes that occurred on a softwood surface. The extent of chemical treatment on softwood was evaluated by determining the weight percent gain values. Thermal properties of modified softwood and the water absorption were also evaluated. The chemical treatment with succinic anhydride influenced the thermal stability of the softwood samples with increasing anhydride concentration levels. 相似文献
42.
Ioan Călinescu Diana Martin Daniel Ighigeanu Adina I. Gavrila Adrian Trifan Mariana Patrascu Cornel Munteanu Aurel Diacon Elena Manaila Gabriela Craciun 《Central European Journal of Chemistry》2014,12(7):774-781
Electron beam (EB) irradiation is a useful method to generate stable silver nanoparticles without the interference of inherent impurities generated from chemical reactions. Our experiments were carried out using linear electron beam accelerators with two different EB absorbed dose rates: 2 kGy min?1 and 7–8 kGy s?1, and with different absorbed dose levels. The optimum conditions for silver nanoparticles (AgNPs) generation by radiolysis, or by radiolysis combined with chemical reduction, were established. In order to obtain a good yield for AgNPs synthesized by radiolysis, a high dose rate is required, resulting in a rapid production process. At low absorbed dose rates, the utilization of a stabilization agent is advisable. By modifying the experimental conditions, the ratio between the chemical and radiolytic reduction process can be adjusted, thus it is possible to obtain nanoparticles with tailored characteristics, depending on the desired application.
相似文献
43.
Otilia Culicov Adina Stegarescu Maria-Loredana Soran Ildiko Lung Ocsana Opri Alexandra Ciorî Pavel Nekhoroshkov 《Molecules (Basel, Switzerland)》2022,27(15)
Abiotic stress agents, among them metal stress, can cause oxidative damage to plant cells. In defense, plants can increase the production of secondary metabolites in order to mitigate the harmful effects caused by them. The purpose of this work was to evaluate the effect of two types of copper salts (CuSO4 and Cu(NO3)2), added in two different amounts in soil (150 mg/kg, respectively 300 mg/kg), on assimilating pigments, total polyphenols, antioxidant activity and the elemental composition of wheat. The obtained results were compared with those from control plants grown in the same conditions but without copper salts. The amount of assimilating pigments, total polyphenols, and antioxidant activity respectively increases or decreases in the plants treated with copper salts compared to the control depending on the stage of development of the plant. No significant damage induced in the leaves of the wheat plants treated with the selected salts was observed following the TEM analysis. In six-week-old plants it was observed by EDX analysis that the salts are transformed into nanoparticles. The bioactive compounds, elemental composition and their interaction is influenced by concentration of metal’s salt, type of salt and exposure period. 相似文献
44.
A new sensor for an amplified electrochemical detection of carbohydrates is proposed, where carbohydrates are oxidized by CNT-NiCo-oxide composite in basic solutions. Cyclic voltammograms of the modified electrode show a stable and well defined redox couple in alkaline media due to the synergy of Ni(II)/Ni(III) system with Co(II)/Co(III). The modified electrode shows excellent electrocatalytic activity towards monosaccharides oxidation at reduced overpotential in alkaline solutions. Six monosaccharides were determined amperometrically at the surface of this modified electrode with high sensitivity over a wide range of concentrations, from 0.02 up to 12.12 mM. Low detection limit of 5 μM for glucose could be obtained. 相似文献
45.
Elise Duhamel Alpar Pöllnitz Adina Stegarescu Prof. Dr. Anca Silvestru 《无机化学与普通化学杂志》2011,637(10):1355-1360
Redistribution reactions between diorganodiselenides of type [2‐(R2NCH2)C6H4]2Se2 [R = Et, iPr] and bis(diorganophosphinothioyl disulfanes of type [R′2P(S)S]2 (R = Ph, OiPr) resulted in the hypervalent [2‐(R2NCH2)C6H4]SeSP(S)R′2 [R = Et, R′ = Ph ( 1 ), OiPr ( 2 ); R = iPr, R′ = Ph ( 3 ), OiPr ( 4 )] species. All new compounds were characterized by solution multinuclear NMR spectroscopy (1H, 13C, 31P, 77Se) and the solid compounds 1 , 3 , and 4 also by FT‐IR spectroscopy. The crystal and molecular structures of 3 and 4 were determined by single‐crystal X‐ray diffraction. In both compounds the N(1) atom is intramolecularly coordinated to the selenium atom, resulting in T‐shaped coordination arrangements of type (C,N)SeS. The dithio organophosphorus ligands act monodentate in both complexes, which can be described as essentially monomeric species. Weak intermolecular S ··· H contacts could be considered in the crystal of 3 , thus resulting in polymeric zig‐zag chains of R and S isomers, respectively. 相似文献
46.
Organohalogen compounds, principally brominated aromatics, continue to be the largest selling flame retardants worldwide. However, there is increasing concern about the bioaccumulation and potential toxicity of these compounds. Consequently, there is great interest in the development of effective alternatives to these materials. Organophosphorus compounds seem to offer the most promise as replacements for halogen-containing flame retardants. One approach to flame-retarding vinyl polymers is to develop reactive monomers containing high levels of phosphorus which may be incorporated directly into the polymer structure. Five phosphorus monomers for use in making fire-retardant copolymers with styrene have been synthesized. A comparative study of the thermal stability of the copolymers has been conducted. Preliminary potential fire behavior data have been obtained using pyrolysis combustion flow calorimetry. 相似文献
47.
Lucica Viorica Ababei Angela Kriza Cristian Andronescu Adina Magdalena Musuc 《Journal of Thermal Analysis and Calorimetry》2012,107(2):573-584
Ten new mononuclear complexes having general formulae [ML2](ClO4)2, M = Cu(II), Co(II), Ni(II), Mn(II) and Zn(II), [ML2](SO4), M = Co(II), Ni(II) and [ML2(H2O)2](SO4), M = Cu(II), Mn(II) and Zn(II), L = 2-acetyl-pyridyl-isonicotinoylhydrazone have been synthesized and characterized based
on elemental analyses, IR spectroscopy, UV–Vis–NIR, EPR, as well as thermal analysis and determination of molar conductivity
and magnetic moments. The structures of [CoL2](ClO4)2 are accomplished by single crystal X-ray diffraction. The coordination sphere is formed by two N, N, O tridentates 2-acetyl-pyridyl-isonicotinoylhydrazone
ligands, or by two N, O bidentate 2-acetyl-pyridyl-isonicotinoylhydrazone and two water molecules. Biological activity studies
reveal a moderate activity of complexes against gram-negative and gram-positive bacteria. 相似文献
48.
X Kong J Qin Z Li A Vultur L Tong E Feng G Rajan S Liu J Lu Z Liang M Zheng W Zhu H Jiang M Herlyn H Liu R Marmorstein C Luo 《Organic & biomolecular chemistry》2012,10(36):7402-7417
Oncogenic mutations in critical nodes of cellular signaling pathways have been associated with tumorigenesis and progression. The B-Raf protein kinase, a key hub in the canonical MAPK signaling cascade, is mutated in a broad range of human cancers and especially in malignant melanoma. The most prevalent B-Raf(V600E) mutant exhibits elevated kinase activity and results in constitutive activation of the MAPK pathway, thus making it a promising drug target for cancer therapy. Herein, we describe the development of novel B-Raf(V600E) selective inhibitors via multi-step virtual screening and hierarchical hit optimization. Nine hit compounds with low micromolar IC(50) values were identified as B-Raf(V600E) inhibitors through virtual screening. Subsequent scaffold-based analogue searching and medicinal chemistry efforts significantly improved both the inhibitor potency and oncogene selectivity. In particular, compounds and possess nanomolar IC(50) values with selectivity for B-Raf(V600E)in vitro and exclusive cytotoxicity against B-Raf(V600E) harboring cancer cells. 相似文献
49.
Adina Jung Volkan Filiz Sofia Rangou Kristian Buhr Petra Merten Janina Hahn Juliana Clodt Clarissa Abetz Volker Abetz 《Macromolecular rapid communications》2013,34(7):610-615
The formation of integral asymmetric membranes from ABC triblock terpolymers by non‐solvent‐induced phase separation is shown. They are compared with the AB diblock copolymer precursors. Triblock terpolymers of polystyrene‐block‐poly(2‐vinylpyridine)‐block‐poly(ethylene oxide) (PS‐b‐P2VP‐b‐PEO) with two compositions are investigated. The third block supports the formation of a membrane in a case, where the corresponding diblock copolymer does not form a good membrane. In addition, the hydrophilicity is increased by the third block and due to the hydroxyl group the possibility of post‐functionalization is given. The morphologies are imaged by scanning electron microscopy. The influence of the PEO on the membrane properties is analyzed by water flux, retention, and dynamic contact angle measurements.
50.
T. Morozan 《随机分析与应用》2013,31(3):299-325
Affine continuous and discrete-time dynamic systems with homogeneous jump Markov perturbations are considered and the existence of an optimal stationary control under a quadratic cost is discussed. In order to solve this problem some new stability results for linear systems with Markov perturbations are given. 相似文献