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51.
Rada M. Popa A. Rada S. Bot A. Culea E. 《Journal of Solid State Electrochemistry》2019,23(8):2435-2445
Journal of Solid State Electrochemistry - Recycled and vanadium-doped materials prepared from the recycling waste electrodes of spent car battery and V2O5 powder produce excellent electrochemical... 相似文献
52.
The results of sorption of acetochlor herbicide with different concentrations (1–15 µg/mL) in inorganic- and organic-modified bentonite are presented. Acetochlor sorption in both bentonite types was studied by attenuated total reflectance spectroscopy in the mid-infrared region and by batch equilibrium method. Infrared spectroscopy results suggest that the interaction of acetochlor with inorganic (or organic) bentonite takes place by mechanism involving the carbonyl stretching vibration and phenyl ring in the acetochlor molecule. The increase of the acetochlor concentration results in red shift of both corresponding band wavenumbers. Batch adsorption study pointed out more expressed sorption of acetochlor in organic bentonite. 相似文献
53.
Glasses in the xWO3·(100 − x)[3B2O3·PbO] system, where 0 ≤ x ≤ 40 mol%, are obtained by conventional melting-quenching method and characterized using X-ray diffraction, FTIR spectroscopy and DFT calculations. These tungsten-lead-borate systems exhibit a photochromic effect which can be induced through laser exposures (λ = 633 nm) directly on the bulk sample. Structural investigations show that the photosensitive effect are due to a reduction of W+ 6 to W+ 5 and/or W+ 4 promoted by the oxidation of Pb+ 4 and some structural changes of the borate network. DFT calculations show higher thermodynamic stability of the [W2O7] and [WO4] polyhedrons comparative with the [WO6] polyhedron. 相似文献
54.
Glasses of the system xSm2O3?(100-x)[6TeO2? 4V2O5] where 0 ≤ x ≤ 50 mol% were prepared and investigated. IR and UV–VIS spectra show that with increase x, the network continuity breaks down with the formation of the larger numbers of non-bridging oxygen. The accommodation of the network with the excess of oxygen ions is possible by the depolymerization of the vanadate network in shorter chains, especially ortho- and pyrovanadate structural units. In order to improve the local orders and to develop crystalline phases the glass samples were kept at 275° C for 7 h. Some structural changes were observed and new crystalline phases, namely Te2V2O9 and SmVO4 crystalline phases appeared in the structure of the samples. Our UV–VIS spectroscopic data show the conversion of the Sm+ 3 to Sm+ 2 species in same time with the oxidation of V+ 3, + 4 to V+ 5 ions. 相似文献
55.
Baošić Rada M. Milojković-Opsenica Dušanka M. Tešić Živoslav Lj. 《平面色谱法杂志一现代薄层色谱法》2004,17(4):250-254
JPC – Journal of Planar Chromatography – Modern TLC - The effect on chromatographic behavior, on thin layers of silica gel, of the electronegativity of ligator atoms has been studied... 相似文献
56.
Jelica Novakovic Olga Papadopoulou Panayota Vassiliou Eleni Filippaki Yannis Bassiakos 《Analytical and bioanalytical chemistry》2009,395(7):2235-2244
Reference Cu-based alloy with chemical composition and micro-chemical structure similar to that of ancient alloys has been
used for carrying out the artificial long-term degradation test based on chloride enriched soil (chemical + soil) degradation.
The results show that such degradation procedure produces natural like “patinas” as the ones grown on archaeological artefacts,
from a chemical, structural and micro-morphological point of view. Glow discharge plasma technique has been employed for the
treatment of the as-corroded bronze coupons. The gradual elimination of chloride-containing corrosion products in favour of
the formation of more stable species and even the complete reduction back to copper has been observed. The chemical and metallurgical
features have been determined by combined use of different analytical techniques such as scanning electron microscopy with
energy dispersive X-ray micro-analysis (SEM-EDS), X-ray diffraction (XRD) and optical microscopy. 相似文献
57.
Let T be a tree and consider the Randi index (T)=
), where v
i
–v
j
runs over all edges of T and (v
i
) denotes the degree of the vertex v
i
. Using counting arguments we show that the Randi index, is monotone increasing over the well (lexicographic order) ordered sequence of trees with unique branched vertex. 相似文献
58.
59.
Dr. Adriana Sierra-Romero Dr. Katarina Novakovic Prof. Mark Geoghegan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(2):e202310750
Commercial adhesives typically fall into two categories: structural or pressure sensitive. Structural glues rely on covalent bonds formed during curing and provide high tensile strength whilst pressure-sensitive adhesives use physical bonding to provide weaker adhesion, but with considerable convenience for the user. Here, a new class of adhesive is presented that is also reversible, with a bond strength intermediate between those of pressure-sensitive and structural adhesives. Complementary water-based formulations incorporating oppositely charged polyelectrolytes form electrostatic bonds that may be reversed through immersion in a low or high pH aqueous environment. This electrostatic adhesive has the advantageous property that it exhibits good adhesion to low-energy surfaces such as polypropylene. Furthermore, it is produced by the emulsion copolymerization of commodity materials, styrene and butyl acrylate, which makes it inexpensive and opens the possibility of industrial production. Bio-based materials have been also integrated into the formulations to further increase sustainability. Moreover, unlike other water-based glues, adhesion does not significantly degrade in humid environments. Because such electrostatic adhesives do not require mechanical detachment, they are appropriate for the large-scale recycling of, e.g., bottle labels or food packaging. The adhesive is also suitable for dismantling components in areas as varied as automotive parts and electronics. 相似文献
60.
Glasses in the system xGd2O3(100 − x)[7GeO2·3PbO] with 0 ≤ x ≤ 40 mol% have been prepared from melt quenching method. The influence of gadolinium ions on structural behavior in lead-germanate glasses has been investigated using FTIR, UV-VIS and EPR spectroscopy. The structural changes have been analyzed with increasing rare earth concentration.FTIR data suggest that the glass network modifications has taken place mainly in the germanate part whereas the lead part remained unmodified and its network consists mainly from the [GeO4], [GeO6], [Ge2O7] structural units and with interconnected through Ge-O-Ge bridges in [GeO4] structural units. The changes in amplitude and bandwidth of the UV-VIS bands ranging from 200 nm to 350 nm depend on the content of Gd2O3.By increasing the Gd2O3 content in the glass matrix, the optical band gap energy increases, indicating changes of the lattice parameters and that no non-bridging-oxygens form upon the addition of gadolinium oxide. The decreasing trend has been observed both in optical gap band energy and refractive index of oxide glasses at x = 10 mol% Gd2O3 indicating breaks up the [GeO4] tetrahedral units bonds and create of non-bridging oxygen atoms. For sample with x ≥ 20 mol%, the gadolinium ions having a behavior of network formers (g ≈ 4.8) will coordinate more with the excess of oxygen. Accordingly, the gadolinium ions are generally suspected to improve their environment of network formers. 相似文献