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排序方式: 共有195条查询结果,搜索用时 31 毫秒
141.
Ligia Frunza Nicoleta Preda Elena Matei Stefan Frunza Constantin Paul Ganea Aurel Mihai Vlaicu Lucian Diamandescu Angela Dorogan 《Journal of Polymer Science.Polymer Physics》2013,51(19):1427-1437
Electroless deposition was successfully applied in developing crystalline particles of zinc oxide onto polyester textile materials; this deposition is here presented in comparison with other materials made from poly(lactic acid), polyamide or hemp. Structural and spectroscopic characterization of the raw and deposited samples has been performed. The structure of zinc oxide particles was that of wurtzite type as indicated by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Crystallites were 20–500 nm in diameter and up to 1 µm in length. The grown particles cover the fibers not only on the fabric surface but in the textile depth. Contact angle measurement by the sessile drop method was used to study the wettability behavior of the investigated composite systems. The hierarchical roughness structure generates superhydrophobic properties onto polyester fabrics, for which water contact angles exceed 150°. The other functionalized samples also become more hydrophobic after deposition. Cassie‐Baxter model was found suitable to describe the behavior, though the fraction of surface occupied by the water–solid interface is high enough. The electroless deposition technique applied previously for cotton fabrics was once more proven to be highly reproducible, easy scalable, and cheap, allowing a wide range of applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1427–1437 相似文献
142.
Claudiu Lăzăroaie Sorin Eşanu Ciprian Său Răzvan Petre Petrişor-Zamora Iordache Georgios Staikos Traian Rotariu Teodora Zecheru 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1407-1415
Experimental researches were performed in order to determine the combustion temperatures and the visible and infrared screening performances of two pyrotechnic compositions used in decoy flare systems. Morphostructural and morphochemical analyses of the combustion solid products have been correlated with the combustion temperature. For the experimental studies, visible and infrared thermography have been employed, together with dedicated software. The comparative measurements indicated that the thermovision camera enables the acquisition of more accurate results versus the optical pyrometer in terms of data processing, and that the aluminum/polyhalogenated compounds–compositions present visible and infrared screening performances superior to those based on magnesium/polyhalogenated compounds. 相似文献
143.
We describe a simple means of assessing the condition of the superficial lamina propria during endoscopy, which we use in our practice as an adjunct to careful stroboscopic examination. An intake of breath against partially adducted vocal folds serves to draw the mucosa inferomedially into the glottis, which reveals areas of diminished mobility, the relationship of mucosal lesions to deeper tissues of the vocal folds, and subtle submucosal lesions. This is possible because of the unique geometry of the glottis that renders the vector forces of airflow different at inspiration and expiration. Because the integrity of the superficial lamina propria is essential to healthy phonation, we have found the inspiratory maneuver useful across a wide variety of mucosal pathologic conditions. 相似文献
144.
Yiwei Song Fredrik Schaufelberger Zoe Ashbridge Lucian Pirvu Iigo J. Vitorica-Yrezabal David A. Leigh 《Chemical science》2021,12(5):1826
The length and constitution of spacers linking three 2,6-pyridinedicarboxamide units in a molecular strand influence the tightness of the resulting overhand (open-trefoil) knot that the strand folds into in the presence of lanthanide(iii) ions. The use of β-hairpin forming motifs as linkers enables a metal-coordinated pseudopeptide with a knotted tertiary structure to be generated. The resulting pseudopeptide knot has one of the highest backbone-to-crossing ratios (BCR)—a measure of knot tightness (a high value corresponding to looseness)—for a synthetic molecular knot to date. Preorganization in the crossing-free turn section of the knot affects aromatic stacking interactions close to the crossing region. The metal-coordinated pseudopeptide knot is compared to overhand knots with other linkers of varying tightness and turn preorganization, and the entangled architectures characterized by NMR spectroscopy, ESI-MS, CD spectroscopy and, in one case, X-ray crystallography. The results show how it is possible to program specific conformational properties into different key regions of synthetic molecular knots, opening the way to systems where knotting can be systematically incorporated into peptide-like chains through design.Spacers linking 2,6-pyridinedicarboxamide units influence the tightness of the corresponding lanthanide-coordinated overhand knot. β-Hairpin forming motifs generate a metal-coordinated pseudopeptide with a knotted tertiary structure. 相似文献
145.
Miloud Kachi Mohamed Nemamcha Belaid Tabti Lucian Dascalescu 《Journal of Electrostatics》2011,69(4):394-400
Surface potential decay method has been frequently used to characterize the charge state of insulating materials. The present paper aims at a critical evaluation of this method when used for the characterization of granular plastics, by comparing it with the electric field monitoring by means of non-contact vibrating probes, and with the measurement of the charge induced in a capacitive probe connected to a Coulomb-meter. The experiments were performed on corona-charged polyethylene, polycarbonate, polyamide, and acetyl – butadiene – styrene granular materials. The experimental results show that surface potential decays faster than the electric field or the charge measured with the capacitive probe. The dimensions of the probes and the capacitive coupling between them and the samples, may explain this difference. Part of the potential decay measured by the smaller-size probe of the electrostatic voltmeter is due to the surface conduction, while the measurements made with the larger-size electric field and capacitive probes are less affected by this phenomenon. 相似文献
146.
Lucian Beznea 《Journal of Mathematical Analysis and Applications》2011,384(1):33-48
We obtain a criterion for the quasi-regularity of generalized (non-sectorial) Dirichlet forms, which extends the result of P.J. Fitzsimmons on the quasi-regularity of (sectorial) semi-Dirichlet forms. Given the right (Markov) process associated to a semi-Dirichlet form, we present sufficient conditions for a second right process to be a standard one, having the same state space. The above mentioned quasi-regularity criterion is then an application. The conditions are expressed in terms of the associated capacities, nests of compacts, polar sets, and quasi-continuity. The second application is on the quasi-regularity of the generalized Dirichlet forms obtained by perturbing a semi-Dirichlet form with kernels. 相似文献
147.
Ocsana Opri Florina Copaciu Maria Loredana Soran Ülo Niinemets Lucian Copolovici 《Molecules (Basel, Switzerland)》2021,26(15)
Persistent pollutants such as pharmaceuticals, pesticides, musk fragrances, and dyes are frequently detected in different environmental compartments and negatively impact the environment and humans. Understanding the impacts of diffuse environmental pollutants on plants is still limited, especially at realistic environmental concentrations of contaminants. We studied the effects of key representatives of two major classes of environmental pollutants (nine different antibiotics and six different textile dyes) on the leaf carotenoid (violaxanthin and neoxanthin) content in wheat (Triticum aestivum L.) using different pollutant concentrations and application times. The wheat plants were watered with solutions of selected environmental pollutants in two different concentrations of 0.5 mg L−1 and 1.5 mg L−1 for one week (0.5 L) and two weeks (1 L). Both categories of pollutants selected for this study negatively influenced the content of violaxanthin and neoxanthin, whereas the textile dyes represented more severe stress to the wheat plants. The results demonstrate that chronic exposure to common diffusively spread environmental contaminants constitutes significant stress to the plants. 相似文献
148.
149.
Fatima Rahou Amar Tilmatine Mihai Bilici Lucian Dascalescu 《Journal of Electrostatics》2013,71(5):867-874
Numerical simulation has proved to be a powerful tool in the research and development of new electrostatic processes. In a previous paper, the authors have introduced a simple mathematical model for simulating the outcome of a novel tribo-aero-electrostatic separation process for binary mixtures of granular materials. The mathematical model assumed that the probability of a granule to be separated can be expressed as a function of the number of impacts with granules belonging to the other class of materials. The process is characterized by the fact that the charging of the granules is produced in a fluidized bed device, in the presence of an electric field. The aim of the present paper is to simulate the continuous operation of such a device at various feed rates. The evolution in time of the mass of granules collected at the electrodes has been computed for various compositions of the granular mixture. The effect of the walls was taken into account. The computed results were in good agreement with the experiments. They demonstrate that open-loop continuous operation of the separator is possible for a range of feed-rates that depends on the composition of the materials to be separated. 相似文献
150.
We propose a self-consistent molecular theory of conformational properties of flexible polymers in solution. It is applied to the collapse of a hydrophobic polymer chain in water, and can be readily generalized to any polymer-solvent system (e.g., copolymers with high complexity). We stress the potential of this method for a variety of problems, such as protein folding. 相似文献