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101.
Base-catalyzed reaction of the nitroketene N,S-acetals and the ring substituted 2-hydroxybenzaldehydes afforded a combinatorial library of the 2-alkylamino-3-nitro-4-alkylsulfanyl 4H-chromenes in excellent yields. Nucleophilic displacement of the C4 alkylsulfanyl group with different thiols afforded 4H-chromenes with structural diversity. 相似文献
102.
Freestanding conducting polyaniline film for the control of electromagnetic radiations 总被引:2,自引:0,他引:2
Electromagnetic interference is pollution generated due to dense nature of circuitry in electronic devices and is required to be control at its source. Polyaniline is an environmentally stable conducting polymer which can be cast as thin film, which can replace the corrosive metals as a shield for the control of electromagnetic radiations. In this communication we discuss our results on the preparation of flexible freestanding conducting polyaniline film of varied thickness using either p-toluenesulphonic acid (PTSA) or camphor-10-sulphonic acid as a primary dopant and 4-chloro-3-methyl phenol (CMC) as a secondary dopant. The resulting films were characterized by conductivity, scanning electron micrograph and shielding effectiveness measurements (SE). The SE measurements were carried out using co-axial transmission line method in the frequency range of 0.1–1000 MHz. We noticed that only the change of 2% in the shielding effectiveness of these films over the period of 3 years indicating the environmental stability of polyaniline films. 相似文献
103.
104.
Geetha R. Dholakia W. Fan M. Meyyappan 《Applied Physics A: Materials Science & Processing》2005,80(6):1215-1223
This article discusses the self assembly of conjugated thiol molecular wires on Au(111) substrates and their charge transport studied by scanning tunneling microscopy and spectroscopy. Molecular resolution imaging of the conjugated thiols show that differences in their structure and inter molecular interactions result in an ordering on gold that is different from the hexagonal symmetry found in alkanethiols. Tunneling spectroscopy on the molecular wires provides information about their intrinsic electronic properties such as the origin of the observed conductance gap and asymmetry in the I–Vs. Further by concurrent topographic and tunneling spectroscopic studies on a conjugated thiol molecule self assembled with and without molecular order, we show that packing and order determine the response of the monolayer to various competing interactions and that the presence of molecular order is very important for reproducible transport measurements. Competing forces between the electric field, intermolecular interactions, tip-molecule physisorption and substrate-molecule chemisorption impact the transport measurements and its reliability. This study points to the fact that molecular electronic devices should be designed to be tolerant to such fluctuations and dynamics. PACS 68.37.Ef; 73.63.-b; 81.16.Dn 相似文献
105.
Intuitionistic fuzzy set plays a vital role in decision making, data analysis, and artificial intelligence. Many decision‐making problems consist of different types of datum, where fuzzy set theoretical approaches may fail to obtain the optimal decision. Numerous approaches for intuitionistic fuzzy decision‐making problem have been introduced in the literature to overcome these short comings. But there is no single approach that can be used to solve all kinds of problems because of the partial ordering defined on the collection of intuitionistic fuzzy numbers (IFNs). Even though ranking of fuzzy numbers have been studied from early seventies in the last century, a total order on the entire class of fuzzy numbers has been introduced by Wang and Wang (Fuzzy Sets Syst 2014, 243, 131–141) only on 2014. A total order on the collection of all IFN is an open problem till today. In this article, a total order on the entire class of IFN using upper lower dense sequence in the interval [0, 1] is proposed and compared with existing techniques using illustrative examples, further an algorithm (which is problem independent) for solving any intuitionistic fuzzy multicriteria decision‐making problem (Intuitionistic fuzzy MCDM) is introduced. This new total ordering on IFNs generalizes the total ordering defined in Wang and Wang ( 22 ) for fuzzy numbers. © 2016 Wiley Periodicals, Inc. Complexity 21: 54–66, 2016 相似文献
106.
107.
Abulencia A Adelman J Affolder T Akimoto T Albrow MG Ambrose D Amerio S Amidei D Anastassov A Anikeev K Annovi A Antos J Aoki M Apollinari G Arguin JF Arisawa T Artikov A Ashmanskas W Attal A Azfar F Azzi-Bacchetta P Azzurri P Bacchetta N Badgett W Barbaro-Galtieri A Barnes VE Barnett BA Baroiant S Bartsch V Bauer G Bedeschi F Behari S Belforte S Bellettini G Bellinger J Belloni A Benjamin D Beretvas A Beringer J Berry T Bhatti A Binkley M Bisello D Blair RE Blocker C Blumenfeld B Bocci A 《Physical review letters》2007,98(16):161801
We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1 fb;-1 of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7+/-0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to 6 standard deviations. The measured cross section is sigma(pp-->WZ)=5.0(-1.6)(+1.8) pb, consistent with the standard model expectation. 相似文献
108.
The aim of this study was to evaluate the gastroprotective efficacy of andrographolide isolated from Andrographis paniculata in rats induced with duodenal ulcers. Duodenal ulcers were induced by cysteamine administration in rats pretreated with 3?mg?kg?1 BW?day?1 of andrographolide for 30 days. Ulcer score, myeloperoxidase activity, TBARS level, GSH/GSSG ratio and enzyme antioxidants were measured in the duodenal tissue. Brush border and basolateral membranes were isolated to assay sucrase, maltase, alkaline phosphatase and total ATPases. Ulcer score was significantly minimised in rats pretreated with andrographolide. Elevation in myeloperoxidase and TBARS levels were found to be minimised significantly due to andrographolide treatment. Membrane-bound enzyme activities and the thiol redox status of glutathione were significantly maintained in duodenal mucosa of rats that received andrographolide. This study reveals that the major component of A. paniculata, andrographolide, has potent antiulcer properties that are most likely caused by minimising inflammatory changes, counteracting free radical formation and maintaining the thiol redox status in the duodenum. 相似文献
109.
J.?García-Lavandeira P.?Oliveri J.?A.?Martínez-Pontevedra M.?H.?Bollaín M.?Forina R.?CelaEmail author 《Analytical and bioanalytical chemistry》2011,399(6):1951-1964
The use of high temperatures (above 100 °C) in reversed-phase liquid chromatography (RP-HTLC) has opened up novel and enhanced
applications for this essential separation technique. Although the favourable effects of temperature on LC have been extensively
studied both theoretically and practically, its potential application to method development has barely been investigated.
These favourable effects include enhanced speed, efficiency, resolution and detectability, as well as changes in selectivity,
especially for polar and ionisable compounds, and the emergence of new options such as temperature programming and the concomitant
use of solvent and temperature gradients, green separations, and so on. The recent availability of silica-based columns that
routinely support high temperatures in addition to more conventional temperature-resistant columns (based on graphitised carbon,
polymers and zirconium oxide) and dedicated column ovens that allow accurate temperature control up to 200 °C makes it possible
to conceive of RP-HTLC as a routine separation technique in the modern analytical laboratory. On the other hand, the addition
of temperature as a new optimisable parameter to RPLC adds further complexity to method development. Thus, new computer-assisted
optimisation tools that extend the capabilities of current computer-assisted tools are being specifically developed for this
type of separation. A new specially developed computer-assisted method development (CAMD) tool is presented herein, and its
efficiency is demonstrated. This CAMD is based on the development of a rugged retention model for peaks, allowing the simulation
of any kind of RP-HTLC separation, including isocratic, linear, curved, multilinear and stepwise gradients of solvent composition
concomitant with constant, linear and multilinear temperature gradients. Both the retention models and the unattended optimisation
of separations are driven by evolutionary algorithms, thus providing negligible-cost, rapid, highly efficient, and user-friendly
optimisation processes. 相似文献
110.
Prakash M Geetha D Caroline ML Ramesh PS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,82(1):461-466
The mineral crandallite CaAl3(PO4)2(OH)5·(H2O) has been identified in deposits found in the Jenolan Caves, New South Wales, Australia by using a combination of X-ray diffraction and Raman spectroscopic techniques. A comparison is made between the vibrational spectra of crandallite found in the Jenolan Caves and a standard crandallite. Raman and infrared bands are assigned to PO43− and HPO42− stretching and bending modes. The predominant features are the internal vibrations of the PO43− and HPO42− groups. A mechanism for the formation of crandallite is presented and the conditions for the formation are elucidated. 相似文献