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51.
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
52.
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
53.
Laurent Pierre-Jean Mazure Marie-Laurence Maxim Voichiţa Teodora 《Numerical Algorithms》1997,15(3-4):373-383
A parametric spline curve is defined whose restriction to each sub-interval belongs to a 4-dimensional piecewise Chebyshev
subspace depending on coefficients which play the role of shape parameters.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
54.
Dr. Adina Borbély Dr. Fabien Thoreau Dr. Eduard Figueras Malika Kadri Dr. Jean-Luc Coll Dr. Didier Boturyn Prof. Dr. Norbert Sewald 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(12):2602-2605
The effective delivery of cytotoxic agents to tumor cells is a key challenge in anticancer therapy. Multivalent integrinspecific ligands are considered a promising tool to increase the binding affinity, selectivity, and internalization efficiency of small-molecule drug conjugates. Herein, we report the synthesis and biological evaluation of a multimeric conjugate containing the high-affinity integrin αvβ3 binding ligand RAFT-c(RGDfK)4, a lysosomally cleavable Val-Cit linker, and cryptophycin-55 glycinate, a potent inhibitor of tubulin polymerization. In vitro cytotoxicity assays verified that the multimeric RGD-cryptophycin conjugate displays improved potency compared to the monomeric analogue in integrin αvβ3 overexpressing tumor cell lines, while significantly reduced activity was observed in the integrin-negative cell line. 相似文献
55.
Petru Blaga Teodora C?tina? Gheorghe Coman 《Applied mathematics and computation》2011,218(7):3072-3082
We construct and analyze Bernstein-type operators on triangles with curved sides, their product and Boolean sum. We study the interpolation properties and approximation accuracy. Using the modulus of continuity we also study the remainders of the corresponding approximation formulas. Finally, there are given some particular cases and numerical examples. 相似文献
56.
Staneva G Lupanova T Chachaty C Petkova D Koumanov K Pankov R Momchilova A 《Journal of colloid and interface science》2011,354(1):202-209
In this paper, folate conjugated poly(ε-caprolactone-co-4-maleate-ε-caprolactone) (P(CL-co-MCL)-folate) was prepared by a carbodiimide coupling reaction, i.e., the vitamin folic acid (FA) was covalently linked to the main chain of the maleate-functionalized polymer, poly(ε-caprolactone-co-4-maleate-ε-caprolactone) (P(CL-co-MCL)). Then the 5-Fluorouracil (5-FU) loaded nanoparticles of P(CL-co-MCL)-folate were achieved by solvent-evaporation method. Their properties were extensively studied by dynamic light scattering (DLS) and scan electron microscopy (SEM). DLS and SEM showed that the nanoparticles were in a well-defined spherical shape with a uniform size distribution. We also investigated the entrapment and in vitro release behavior, which indicated that the release speed of 5-FU could be well controlled and the release half-life period could reach 16.86h, which was 26.4 times longer than that of pure 5-FU. The in vitro targeting test displayed that the 5-FU loaded P(CL-co-MCL)-folate nanoparticles exhibited an enhanced cell inhibition because folate targeting increased the concentration of 5-FU loaded P(CL-co-MCL)-folate nanoparticles in the tumor cells with folate receptor overexpressed. Meanwhile, the tumor inhibition of 5-FU loaded P(CL-co-MCL)-folate nanoparticles was much higher than that of pure 5-FU and that of 5-FU loaded P(CL-co-MCL) nanoparticles. Therefore, P(CL-co-MCL)-folate nanoparticles would be highly beneficial for biomedical and pharmaceutical applications. 相似文献
57.
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
58.
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
59.
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
60.
Vegso K Siffalovic P Majkova E Jergel M Benkovicova M Kocsis T Weis M Luby S Nygård K Konovalov O 《Langmuir : the ACS journal of surfaces and colloids》2012,28(28):10409-10414
We report on an in-situ observation of the colloidal silver nanoparticle self-assembly into a close-packed monolayer at the air/water interface followed by a 2D to 3D transition. Using the fast tracking GISAXS technique, we were able to observe the immediate response to the compression of the self-assembled nanoparticle layer at the air/water interface and to identify all relevant intermediate stages including those far from the equilibrium. In particular, a new nonequilibrium phase before the monolayer collapse via the 2D to 3D transition was found that is inaccessible by the competing direct space imaging techniques such as the scanning and transmission electron microscopies due to the high water vapor pressure and surface tension. 相似文献