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71.
This paper presents and compares two capacitive humidity sensors with interdigitated electrodes for a portable clinical application. A polyimide-sensitive layer covers the first structures and the optimized ones include a benzocyclobutene-sensitive layer and a heating resistor. Humidity measurements results are presented, in particular sensors response time in absorption, which are very small (inferior to 500 ms). Next, mechanisms of absorption and adsorption in a polymer layer are described and the two structures are compared. Suitability of optimized sensors for our application is discussed: new structures allow us to increase sensitivity and decrease response time. When the structure is maintained at 40 degrees C by its heater, the response time is 200 ms and the total desorption time is 11 s. 相似文献
72.
Esteves AC Monteiro OC Barros-Timmons AM Boemare C Soares MJ Monteiro T Trindade T 《Journal of nanoscience and nanotechnology》2002,2(2):177-181
Hybrid materials consisting of SiO2/CdS particles dispersed in poly(styrene-co-maleic anhydride) and poly(styrene-co-maleimide) have been synthesized and characterized. The polymer nanocomposites were synthesised in situ in the presence of previously prepared inorganic fillers (SiO2/CdS). The nanocomposites were synthesized with the use of as-prepared or surface-modified SiO2/CdS fillers. For both types of nanocomposites, the optical properties were evaluated and the observation of size quantization effects in the optical spectra is discussed. In this context, the influence of the inorganic fillers and polymer matrices on the optical properties of the final nanocomposites was investigated. 相似文献
73.
We provide a detailed analysis of the various problems connected with the development of tunable thin-film filters for wavelength-division multiplexing applications. We examine the relation between the change in layer thickness and the central wavelength shift for various configurations and point out the significance of the structure of the reflectors, the spacer thickness, and the location of the active layers. We describe and compare practical arrangements using either temperature or an electric field as the driving parameter. 相似文献
74.
Montcalm C Grabner RF Hudyma RM Schmidt MA Spiller E Walton CC Wedowski M Folta JA 《Applied optics》2002,41(16):3262-3269
We present our results of coating a first set of optical elements for an extreme-ultraviolet (EUV) lithography system. The optics were coated with Mo-Si multilayer mirrors by dc magnetron sputtering and characterized by synchrotron radiation. Near-normal incidence reflectances above 65% were achieved at 13.35 nm. The run-to-run reproducibility of the reflectance peak wavelength was maintained to within 0.4%, and the thickness uniformity (or gradient) was controlled to within +/-0.05% peak to valley, exceeding the prescribed specification. The deposition technique used for this study is an enabling technology for EUV lithography, making it possible to fabricate multilayer-coated optics to accuracies commensurate with atomic dimensions. 相似文献
75.
Aerosol extinction coefficients have been derived in the 375-700-nm spectral domain from measurement in the stratosphere since 1992, at night, at mid- and high latitudes from 15 to 40 km, by two balloonborne spectrometers, Absorption par les Minoritaires Ozone et NO(chi) (AMON) and Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NO(chi) (SALOMON). Log-normal size distributions associated with the Mie-computed extinction spectra that best fit the measurements permit calculation of integrated properties of the distributions. Although measured extinction spectra that correspond to background aerosols can be reproduced by the Mie scattering model by use of monomodal log-normal size distributions, each flight reveals some large discrepancies between measurement and theory at several altitudes. The agreement between measured and Mie-calculated extinction spectra is significantly improved by use of bimodal log-normal distributions. Nevertheless, neither monomodal nor bimodal distributions permit correct reproduction of some of the measured extinction shapes, especially for the 26 February 1997 AMON flight, which exhibited spectral behavior attributed to particles from a polar stratospheric cloud event. 相似文献
76.
77.
78.
The oxidative degradation of phospholipids in the presence and absence of plasmalogens (plasmenyl phosphatidylethanolamine:
PPE) was followed by chemical analysis. Human platelet phospholipids, either intact or after removal of PPE by acid treatment,
were oxidized with 28 mM 2,2′-azobis(2-amidinopropane di-HCl in Triton X-100 micelles (detergent/phospholipid 5∶1, mol/mol).
PPE (12% of all phospholipids, mol/mol) disappeared about three times more rapidly than glycerophospholipids, whereas sphingomyelin
remained unaltered and the lysophosphatidylethanolamine (lysoPE) generated became progressively more unsaturated. After 60
min oxidation, the FA compositions of PS, PC, and PI were similar in extracts with or without plasmalogens. In contrast, diacyl
phosphatidylethanolamine (DPE) became more saturated in the absence of PPE. The rate of phospholipid destruction was always
unique to each class, but for all phospholipids slowed down in the presence of PPE. This protective effect increased in the
order DPE<PS<PC<PI and did not seem to be simply related to the class unsaturation. α-Tocopherol had no influence on the time
courses of the quantities and compositions of the phospholipids, even at a molar ratio of α-tocopherol to phospholipids four
times higher than in platelet membranes. Thus, PPE protected phospholipids efficiently but differentially against peroxidative
attack, whereas the contribution of α-tocopherol appeared to be negligible even at a concentration four times greater than
in platelet membranes. 相似文献
79.
Carrasco C Rosu F Gabelica V Houssier C De Pauw E Garbay-Jaureguiberry C Roques B Wilson WD Chaires JB Waring MJ Bailly C 《Chembiochem : a European journal of chemical biology》2002,3(12):1235-1241
The structural selectivity of the DNA-binding antitumor drug ditercalinium was investigated by competition dialysis with a series of nineteen different DNA substrates. The 7H-pyridocarbazole dimer was found to bind to double-stranded DNA with a preference for GC-rich species but can in addition form stable complexes with triplex and quadruplex structures. The preferential interaction of the drug with four-stranded DNA structures was independently confirmed by electrospray mass spectrometry and a detailed analysis of the binding reaction was performed by surface plasmon resonance (SPR) spectroscopy. The BIAcore SPR study showed that the kinetic parameters for the interaction of ditercalinium with the human telomeric quadruplex sequence are comparable to those measured with a duplex sequence. Slow association and dissociation were observed with both the quadruplex and duplex structures. The newly discovered preferential binding of ditercalinium to the antiparallel quadruplex sequence d(AG(3)[T(2)AG(3)](3)) provides new perspectives for the design of drugs that can bind to human telomeres. 相似文献
80.
Quang Huy Nguyen Claude Kirchner Hélène Kirchner 《Journal of Automated Reasoning》2002,29(3-4):309-336
This paper presents the design, the implementation, and experiments of the integration of syntactic, conditional possibly associative-commutative term rewriting into proof assistants based on constructive type theory. Our approach is called external because it consists in performing term rewriting in a specific and efficient environment and checking the computations later in a proof assistant. Two typical systems are considered in this work: ELAN, based on the rewriting calculus, as the term rewriting-based environment, and Coq, based on the calculus of inductive constructions as the proof assistant. We first formalize the proof terms for deduction by rewriting and strategies in ELAN using the rewriting calculus with explicit substitutions. We then show how these proof terms can soundly be translated into Coq syntax where they can be directly type checked. For the method to be applicable for rewriting modulo associativity and commutativity, we provide an effective method to prove equalities modulo these axioms in Coq using ELAN. These results have been integrated into an ELAN-based rewriting tactic in Coq. 相似文献