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611.
Andreia F. Sousa Marina Matos Ricardo J. B. Pinto Carmen S. R. Freire Armando J. D. Silvestre 《Cellulose (London, England)》2014,21(3):1723-1733
The use of renewable feedstocks in foam technology has created a worldwide demand for more sustainable materials. Castor oil is a vegetable oil, composed mainly of triricinoglycerol, a natural polyol, suitable for polyurethane foam production. In this study, castor oil and variable amounts of microcrystalline cellulose (MCC) fibers were used in a straightforward one-pot synthesis approach for the preparation of novel biofoams. The ensuing biofoams were characterized by several techniques, including attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis, and their mechanical performance was evaluated by compression mechanical testing and by dynamic mechanical thermal analysis. They were (semi-) flexible, with a cell-like morphology and reinforced toughness due to the use of MCC. They had a Young’s modulus varying between 0.188 and 1.06 MPa depending on the amount of MCC used and were thermally stable up to 267 °C. The properties of these novel biofoams enable them to be strong candidates for use as tough, energy-absorbing foams, advantageously prepared using renewable-based resources. 相似文献
612.
Simplified Electrochemically Mediated Atom Transfer Radical Polymerization using a Sacrificial Anode
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Sangwoo Park Paweł Chmielarz Armando Gennaro Krzysztof Matyjaszewski 《Angewandte Chemie (International ed. in English)》2015,54(8):2388-2392
Simplification of electrochemically mediated atom transfer radical polymerization was achieved efficiently under either potentiostatic or galvanostatic conditions using an aluminum wire sacrificial anode (seATRP) immersed directly into the reaction flask without separating the counter electrode. seATRP polymerizations were carried out under different applied potentials, Eapps=E1/2, Epc, Epc ?40 mV, and Epc ?80 mV. As the rate of polymerization (Rp) can be modulated by applying different Eapp potentials, more reducing conditions resulted in faster Rp. The polymerization results showed similar narrow molecular‐weight distribution throughout the reactions, similar to results observed for n‐butyl acrylate (BA) polymerization under conventional eATRP. High‐molecular‐weight PBA and diblock copolymers were synthesized by seATRP with more than 90 % monomer conversion. Furthermore, galvanostatic conditions were developed for synthesizing PBA with the two‐electrode system. 相似文献
613.
Pankaj Sharma Noe Rosas Armando Cabrera M. J. Silva Hernandez Alfredo Toscano Simn Hernndez Rene Gutierrez 《应用有机金属化学》2005,19(10):1121-1126
New stibine and bismuthine substituted thienyl ring compounds, i.e. tris(3‐methyl‐2‐thienyl)stibine (1), tris(3‐methyl‐2‐thienyl)bismuthine (2), tris(3‐thienyl)stibine (3), tris(3‐thienyl)bismuthine (4) and tris(5‐chloro‐2‐thienyl)stibine (5), have been synthesized and characterized by IR, mass, 1H, 13C, COSY, and HETCOR NMR spectroscopy. The metal centres in all compounds are pyramidal, and molecules in the stibine compound (1) and bismuthine compound (2) associate via Sb···S or Bi···S interactions to form supramolecular chains. The cytotoxicity of compounds 1 and 5 was determined. For compound 5, 85% of carcinogenic cell growth inhibition (U, K and H) was observed. Compound 1 shows a significant selectivity (>80%) for carcinogenic cell growth (K and U) inhibition. Both the compounds are highly toxic for the growth of normal lymphocytes with ~95% lethality. Compound 1 is approximately 20 times more toxic than 5 against Artemia salina. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
614.
Armando Chiellini 《Annali di Matematica Pura ed Applicata》1934,13(1):41-54
Sunto L'Autore mostra dapprima come sia possibile il sostituire, in un caso particolare, la funzione
con un' altra più semplice; inoltre come mediante questa nuova funzione, oltre che mediante la funzioneE diWeierstrass, sia possibile applicare i metodi diretti del prof.Tonelli alla ricerca dell'estremo di un integrale della forma
ds. Infine mostra, per tale caso particolare, un'interessante conseguenza geometrica delle equazioni diEulero. 相似文献
615.
For the first time, the L-proline-catalyzed direct asymmetric self-aldolization of acetaldehyde is described affording (+)-(5S)-hydroxy-(2E)-hexenal 2 with ee's ranging from 57 to 90%. Further transformations of 2 into synthetically valuable building blocks are presented. A mechanism for the formation of 2 is proposed. 相似文献
616.
Anna Avallone 《Czechoslovak Mathematical Journal》2002,52(3):499-512
We prove that every modular function on a multilattice L with values in a topological Abelian group generates a uniformity on L which makes the multilattice operations uniformly continuous with respect to the exponential uniformity on the power set of L. 相似文献
617.
Rebeca P. Medina Vagner M. de Moura Cleuza C. da Silva Cecília M. A. de Oliveira Lucilia Kato Armando M. Pomini 《Natural product research》2018,32(11):1357-1360
The crude extract and fractions from the branches of Ixora brevifolia, a tree found in the Brazilian Cerrado, were tested for anti-inflammatory and in vitro antiproliferative effects. The crude extract and n-hexane fraction exhibited significant inhibition of ear oedema in mice, while n-hexane-precipitated and chloroform fractions strongly inhibited the myeloperoxidase activity in ear tissue. The n-hexane and n-hexane-precipitated fractions showed strong growth inhibition for glioma cell line and the hydromethanolic fraction inhibited the growth of leukaemia cell line. 相似文献
618.
Let g be a Riemannian metric on the 2-sphere S2. Results on isometric embeddings of (S2, g) into a fixed model manifold often have implications in quasi-local mass related problems in general relativity. In this paper, motivated by the definitions of the Brown–York and the Wang–Yau mass, we consider isometric embeddings of (S2, g) into conformally flat spaces. We prove that if g is close to the standard metric on S2, then (S2, g) admits an isometric embedding into any spatial Schwarzschild manifold with small mass. We also give a sufficient condition that ensures isometric embeddings of perturbations of a Euclidean convex surface into \({\mathbb{R}^3}\) equipped with a conformally flat metric. 相似文献
619.
Magdalena Domarus Dr. Maxim L. Kuznetsov Dr. Joaquim Marçalo Prof.Dr. Armando J. L. Pombeiro Dr. José Armando L. da Silva 《Angewandte Chemie (International ed. in English)》2016,55(4):1489-1492
The vanadium(IV) N‐hydroxyiminodicarboxylate complexes [V(HIDPA)2]2? and [V(HIDA)2]2?, close models of the amavadin (a natural product from Amanita fungi lacking the V=O group but exhibiting a rare NO‐bound oxyiminate moiety), are shown to be the first recognized complexes of the early transition metals (up to periodic Group 7) that mediate the oxidation of water. The reactions were analyzed by visible spectrophotometry, mass spectrometry, and measurement of evolved dioxygen using Ce4+ as sacrificial oxidant. A mechanism proposed on the basis of DFT calculations involves the reversible oxidation to the mononuclear VV‐{ON˙<} center, where the redox active oxyimino group plays a key role and metal oxidation state variation is only one unit. The more similar model of the metallobiomolecule, [V(HIDPA)2]2?, displays a lower oxidation rate than [V(HIDA)2]2? but does not undergo appreciable degradation, in contrast to the latter. 相似文献
620.
Prof. Dr. J. Armando Luján-Montelongo Dr. Jeferson B. Mateus-Ruiz Ricardo M. Valdez-García 《European journal of organic chemistry》2023,26(9):e202201156
This review provides a comprehensive overview of strategies and methodologies for reducing C−O and heteroatomic−oxygen bonds (N−O, S−O, P−O) using I2/I−, as well as other synthetically relevant bonds such as C−C, N−N, C−N, C−X, C−S. It highlights and discusses most of the mechanistic details provided by the original authors. Selected examples of other halides (Br and Cl) as reductants are also covered. 相似文献