排序方式: 共有83条查询结果,搜索用时 93 毫秒
41.
42.
L. A. Gómez C. B. de Araújo R. Putvinskis S. H. Messaddeq Y. Ledemi Y. Messaddeq 《Applied physics. B, Lasers and optics》2009,94(3):499-502
Nonlinear (NL) optical properties of antimony–germanium–sulfur (Sb–Ge–S) glasses were investigated using laser pulses of 65 fs
at 1560 nm. Samples having concentration ratio [S]/[Ge]=2.69 with different antimony concentrations were studied. Glasses
with different oxidation states of Sb were investigated using the thermally
managed
Z
-scan technique. The influence of the Sb oxidation state on the NL properties was evaluated. NL refraction indices of electronic origin,
n
2≈10−13 cm2/W, two-orders of magnitude larger than for fused silica and NL absorption coefficients smaller than 0.55 cm/GW were measured.
Appropriate figures-of-merit for photonic applications were determined. 相似文献
43.
Tambelli CC Donoso JP Magon CJ Bueno LA Messaddeq Y Ribeiro SJ de Oliveira LF Kosacki I 《The Journal of chemical physics》2004,120(20):9638-9647
Glass structure and fluorine motion dynamics are investigated in lead-cadmium fluorgermanate glasses by means of differential scanning calorimetry, Raman scattering, x-ray absorption (EXAFS), electrical conductivity (EC), and (19)F nuclear magnetic resonance (NMR) techniques. Glasses with composition 60PbGeO(3)-xPbF(2)-yCdF(2) (in mol %), with x+y=40 and x=10, 20, 30, 40, are studied. Addition of metal fluorides to the base PbGeO(3) glass leads to a decrease of the glass transition temperature (T(g)) and to an enhancement of the ionic conductivity properties. Raman and EXAFS data analysis suggest that metagermanate chains form the basic structural feature of these glasses. The NMR study leads to the conclusion that the F-F distances are similar to those found in pure crystalline phases. Experimental results suggest the existence of a heterogeneous glass structure at the molecular scale, which can be described by fluorine rich regions permeating the metagermanate chains. The temperature dependence of the NMR line shapes and relaxation times exhibits the qualitative and quantitative features associated with the high fluorine mobility in these systems. 相似文献
44.
Balesteros MR Tavares MF Ribeiro SJ Polachini FC Messaddeq Y de Oliveira MA 《Electrophoresis》2007,28(20):3731-3736
In this work, a CE method for the determination of olive oil acidity was proposed. The method was based on an ethanolic extraction (at 60 degrees C) of the oil long-chain free fatty acids (LC-FFAs) components followed by CE determination in pH 6.86 phosphate buffer at 15 mmol/L concentration containing 4 mmol/L sodium dodecylbenzenesulfonate (SDBS), 10 mmol/L polyoxyethylene 23 lauryl ether (Brij 35), 2% v/v 1-octanol and 45% v/v ACN under indirect UV detection at 224 nm. Although this electrolyte promoted baseline separation of myristic acid (C14:0) (internal standard (IS)) and olive oil major components (palmitic acid (C16:0), oleic acid (C18:1c) and linoleic acid (C18:2cc)) in less than 8 min, after a few injections, the electropherogram profiles were severely altered (peak broadening, migration time shifts, etc.) and the current increased substantially. An adsorption study was conducted revealing that the dissolution of the capillary external polyimide coating during the electrophoretic run caused the detrimental effect. After removal of the capillary tip coating, ten consecutive injections could be performed without any disturbances and this simple procedure was, therefore, implemented during quantitative purposes. The reliability of the proposed method was further investigated by the determination of acidity of an extra virgin olive oil sample in comparison to the established methodology (AOCS method Ca 5a-40, alkaline volumetric titration (AVT)). No statistical differences were found within 95% confidence level. A % acidity of 0.39 +/- 0.02 was found for the olive oil sample under consideration. 相似文献
45.
Denise T. B. De Salvi Hernane S. Barud José Maurício A. Caiut Younés Messaddeq Sidney J. L. Ribeiro 《Journal of Sol-Gel Science and Technology》2012,63(2):211-218
Self-supported organic-inorganic hybrid transparent films have been prepared from bacterial cellulose and boehmite. SEM results indicate that the BC membranes are covered by Boehmite and XRD patterns suggest structural changes on cellulose due to Boehmite addition. Thermal stability is accessed through TG curves and is dependent on Boehmite content. Transparency, as evaluated by UV?CVis absorption, increases with increasing content of boehmite suggesting application of these materials as transparent substrates for opto-electronic devices. 相似文献
46.
In this paper, we first establish a Schwarz?CPick type theorem for pluriharmonic mappings and then we apply it to discuss the equivalent norms on Lipschitz-type spaces. Finally, we obtain several Landau??s and Bloch??s type theorems for pluriharmonic mappings. 相似文献
47.
Research on Chemical Intermediates - In the current work, an acidic ionic liquid ([{(IMC)-4-OMBH}BIM][HSO4]3) has been utilized as an effective and recyclable catalyst for the synthesis of... 相似文献
48.
Elaine R. P. Pinto Hernane S. Barud Wagner Luiz Polito Sidney J. L. Ribeiro Younès Messaddeq 《Journal of Thermal Analysis and Calorimetry》2013,114(2):549-555
New nanocomposites based on bacterial cellulose nanofibers (BCN) and polyurethane (PU) prepolymer were prepared and characterized by SEM, FT-IR, XRD, and TG/DTG analyses. An improvement of the interface reaction between the BCN and the PU prepolymer was obtained by a solvent exchange process. FT-IR results showed the main urethane band at 2,270 cm?1 to PU prepolymer; however, in nanocomposites new bands appear as disubstituted urea at 1,650 and 1,550 cm?1. In addition, the observed decrease in the intensity of the hydroxyl band (3,500 cm?1) suggests an interaction between BCN hydroxyls and NCO-free groups. The nanocomposites presented a non-crystalline character, significant thermal stability (up to 230 °C) and low water absorption when compared to pristine BCN. 相似文献
49.
Cid B. de Araújo G. Boudebs V. Briois A. Pradel Y. Messaddeq M. Nalin 《Optics Communications》2006,260(2):723-726
The nonlinear refractive index, n2, of films based on the new glass system Sb2O3–Sb2S3 was measured at 1064 nm with laser pulses of 15 ps, using a single-beam nonlinear image technique in presence of a phase object. The films were prepared from bulk glasses by RF-sputtering. A large value of n2 = 3 × 10−15 m2/W, which is three orders of magnitude larger than for CS2, was determined. The result shows the strong potential of antimony–sulfide glass films for integrated nonlinear optics. 相似文献
50.
We extend some fundamental spectral properties of classic regular Sturm--Liouville problems to discontinuous boundary-value problems with eigenvalue-dependent boundary conditions. We suggest a new approach for investigation of such type discontinuous problems. 相似文献