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1.
We calculate the loss induced in a single-mode rectangular optical waveguide by the presence of a second waveguide, perpendicular to the first, which crosses over the first waveguide at a variable distance d. Our calculation is applied to the analysis of several doped silica waveguides of practical importance for optical circuit design. 相似文献
2.
Cristian Barbarosie Anca‐Maria Toader 《Mathematical Methods in the Applied Sciences》2005,28(9):1089-1114
We prove bounds on the homogenized coefficients for general non‐periodic mixtures of an arbitrary number of isotropic materials, in the heat conduction framework. The component materials and their proportions are given through the Young measure associated to the sequence of coefficient functions. Upper and lower bounds inequalities are deduced in terms of algebraic relations between this Young measure and the eigenvalues of the H‐limit matrix. The proofs employ arguments of compensated compactness and fine properties of Young measures. When restricted to the periodic case, we recover known bounds. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
3.
Anca Bejan Anca Maican Gr. Turcu 《Journal of Radioanalytical and Nuclear Chemistry》1995,201(3):199-204
The recovery of humoral immune response has been comparatively studied by a radioimmunoanalysis (RIA) method and by Mancini single immunoradial diffusion method in an experiment consisting in chronic contamination with low doses of tritiated water (HTO) and oral administration of high doses of ascorbic acid on rats as radioprotector. The radioprotective effect of ascorbic acid was found to be dependent both on the radiation dose and the amount of ascorbic acid administered. 相似文献
4.
Dragulescu-Andrasi A Zhou P He G Ly DH 《Chemical communications (Cambridge, England)》2005,(2):244-246
Guanidine-based peptide nucleic acid (GPNA) with a d-backbone configuration and alternate spacing binds sequence-specifically to RNA and is readily taken up by both human somatic and embryonic stem (ES) cells. 相似文献
5.
Moriarty RM Rani N Enache LA Rao MS Batra H Guo L Penmasta RA Staszewski JP Tuladhar SM Prakash O Crich D Hirtopeanu A Gilardi R 《The Journal of organic chemistry》2004,69(6):1890-1902
A general and novel solution to the synthesis of biologically important stable analogues of prostacyclin PGI(2), namely benzindene prostacyclins, has been achieved via the stereoselective intramolecular Pauson-Khand cyclization (PKC). This work illustrates for the first time the synthetic utility and reliability of the asymmetric PKC route for synthesis and subsequent manufacture of a complex drug substance on a multikilogram scale. The synthetic route surmounts issues of individual step stereoselectivity and scalability. The key step in the synthesis involves efficient stereoselection effected in the PKC of a benzoenyne under the agency of the benzylic OTBDMS group, which serves as a temporary stereodirecting group that is conveniently removed via benzylic hydrogenolysis concomitantly with the catalytic hydrogenation of the enone PKC product. Thus the benzylic chiral center dictates the subsequent stereochemistry of the stereogenic centers at three carbon atoms (C(3a), C(9a), and C(1)). 相似文献
6.
Summary In this paper the internal approximation of a quasi-variational inequality is considered. An algorithm of Bensoussan-Lions type is proposed for which the convergence is proved. These results are applied to Signorini problem with friction for which two error estimates and numerical examples are also given. 相似文献
7.
Alpar Pöllnitz Sevil Irisli Cristian Silvestru Anca Silvestru 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):910-919
The new organophosphorus proligand (OPPh2)(O2SMe)NR (R = C6H3Pri 2–2,6) (3) was prepared as a white crystalline solid by reacting the lithiated compound Li[Ph2P(O)NR] with MeSO2Cl in a 1:1 molar ratio. The precursor Ph2P(O)NHR (1), as well as its thio analogue Ph2P(S)NHR (2), were obtained in the reaction between the lithiated amine RNHLi and the corresponding organophosphorus chloride. All compounds were characterized by multinuclear (1H, 13C, and 31P) NMR spectroscopy. The molecular structures of 1–3 were established by single-crystal X-ray diffraction. A zigzag polymeric chain is formed in the crystals of 1 and 2 by hydrogen N–H···X (X = O, S) bonding, while the crystal of 3 contains discrete monomeric units with a syn–syn conformation of the O?P(C)2–N–S(C)(?O)2 skeleton. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
8.
Anca Moanţă B. Tutunaru P. Rotaru 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1273-1279
The azo-ester, namely 4-(phenyldiazenyl)phenyl 2-furoate (PPF) by a coupling reaction between 4-(phenyldiazenyl)phenol and 2-furoyl chloride in the presence of pyridine was obtained. For characterization of this compound UV–Vis, FTIR, and thermal analysis were used. PPF was investigated as corrosion inhibitor for carbon steel in saline waters using potentiodynamic polarization. Morphology of the surface before and after corrosion was examined by optical microscopy. Potentiodynamic polarization shows that the corrosion current densities decrease and values of polarization resistance and inhibition efficiency increase with PPF concentration reaching a maximum of 89.6 %, at 0.1 mmol L?1. 相似文献
9.
Viorel Cîrcu Doina Mănăilă-Maximean Constantin Roşu Monica Iliş Yann Molard Florea Dumitraşcu 《Liquid crystals》2013,40(2):123-132
A series of ortho-metallated Pd and Pt complexes containing an imine ligand carrying three alkoxy chains and N-benzoylthiourea derivatives as co-ligands were prepared and their liquid crystalline properties investigated. Their structures were assigned based on elemental analysis, IR and 1H NMR spectroscopy, whereas thermal properties were investigated by differential scanning calotimetry and polarising optical microscopy. All the compounds exhibit monotropic transitions involving nematic and smectic A phases, with the mesomorphic behaviour strongly related to the type of N-benzoylthiourea as well as the metal centre used. The thermally stimulated depolarisation current technique was employed to determine the conduction mechanism, phase transition temperature and the activation energies for one of the ortho-metallated Pd complexes. 相似文献
10.
Luminita Andronic Dana Perniu Anca Duta 《Journal of Sol-Gel Science and Technology》2013,66(3):472-480
The TiO2 powders were synthesized by versatile and low cost sol–gel process using HNO3 and titanium tetra-isopropoxide (volumetric ratio of 4:1) following by the hydrolysis reaction. The powders show the two polymorphs of TiO2: 96 % anatase and 4 % brookite, due to acidic condition (pH = 3). Thin films of titanium oxide were obtained by dip-coating, using the sol–gel of titanium oxide mixed with commercial Degussa P25 into a weight ratio 1:1 or 1:1.5, to enhance the synergistic effect of anatase/rutile ratio aiming at increasing the efficiency of the TiO2 photocatalyst in dyes degradation. The thin film surface (charge and morphology) was controlled by polymer (poly-ethylene glycol) and surfactant (Sodium dodecyl sulphate, Triton X100) addition. The titanium oxide was characterized by particle size analyzer, contact angle measurements, X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The photocatalytic properties of powders and coatings were evaluated based on the degradation efficiency of two reference dyes (methyl orange and methylene blue). The results outline that poly(ethylene glycol) and films morphologies are the most influential factors that affecting the photocatalytic activity. 相似文献