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991.
In this work, we have prepared Ag-doped multi-component tellurite glasses by solid state electric field-assisted (SSFA) diffusion. The silver concentration profiles after SSFA diffusion were measured by secondary ion mass spectrometry (SIMS). It is found that the SIMS depth profiles can be well fitted by a classical erfc-like function. And the concentration dependence of silver diffusion coefficient has been investigated by using the Boltzmann-Matano analysis. The refractive index after SSFA diffusion is increased by ?n = 0.025 (λ = 1550 nm) without the glass surface being contaminated. Our results demonstrate that SSFA diffusion is a well controllable, non-destructive method to fabricate planar waveguides based on our newly developed tellurite glasses. 相似文献
992.
René de Gelder Jan M. M. Smits Namakkal G. Ramesh Frank J. A. D. Bakkeren Debby de Groot Antonius J. H. Klunder 《Journal of chemical crystallography》1998,28(6):497-499
The crystal and molecular structure of (+)-(1R, 2S, 6R, 7S, 1R)-5-(1-phenylethylamino)-endo-tricyclo[5.2.1.02,6]deca-4,8-dien-3-one is described. Based on the known absolute configuration (R) of the -phenylethylamine moiety the X-ray analysis revealed the absolute configuration of the title compound. The structure was refined to R
1 = 0.0298 for 1950 reflections (with I > 2(I)). Crystal data: C18H19NO, monoclinic, space group P21, a = 6.7406(4), b = 9.959(2), c = 11.3123(8)Å, = 102.969(5), V = 740.0(2)Å3, and Z = 2. 相似文献
993.
Hongsheng Shi Dingzhong Shen Guohao Ren Haibing Zhang Bo Gong Qun Deng 《Journal of Crystal Growth》2002,240(3-4):459-462
NaBi(WO4)2 (NBW) crystals have been grown for the first time by modified-Bridgman method. Influences of some factors on the crystal growth process are discussed. X-ray powder diffraction experiments show that the unit cell parameters of NBW crystal are a=b=0.5284 nm, c=1.1517 nm, and V=0.3215 nm3. The differential thermal analysis shows that the NBW crystal melts at 923°C. 相似文献
994.
Li Zhang Jing Shi Cheng Li Liu Lang Xiang Shi Ying Ma Wei Li Rui Hua Jiao Ren Xiang Tan Hui Ming Ge 《Tetrahedron letters》2018,59(51):4517-4520
Three new borrelidin-type macrolactones, designated as borrelidins J?L (4–6), together with borrelidin A (1), borrelidin E (2), and 12-desnitrile-12-carboxyl-borrelidin (3) were isolated from a plant endophytic Streptomyces sp. NA06554. Their structures were determined by extensive spectroscopic analysis including HRESIMS, 1D and 2D NMR data. The antibacterial activities for compounds 1–6 were examined. Borrelidins A (1) and L (6) showed potent and moderate antibacterial activity against Micrococcus luteus, respectively, whereas other derivatives (2–5) are almost inactive, which allows us to propose a plausible structure-activity relationship. 相似文献
995.
A mild and efficient method for THP protection of indazoles and benzyl alcohols has been developed in water, the most environmentally friendly solvent, in which Tween 20 (2% w/w) was added to form aqueous micelles to increase the solubility of starting materials. This aqueous protocol allowed the reaction to proceed smoothly at room temperature and with only 1.2 equiv of DHP, providing moderate to good yields of THP protected products for a wide scope of substrates. In addition, the methodology was highly practical in the large-scale synthesis (1?g synthesis of 2c as an example), wherein the convenient work-up and purification procedure (simple filtration) made the protocol even more attractive. 相似文献
996.
Thomas O. Schrader Xiuwen Zhu Michelle Kasem Sufang Li Chunyan Liu Albert Ren Chunrui Wu Graeme Semple 《Tetrahedron letters》2018,59(21):2030-2033
Asymmetric syntheses of N-protected (R)-4-halo-6,6a,7,8,9,10-hexahydro-5H-pyrazino[1,2-a][1,n]naphthyridines, advanced intermediates for the synthesis of highly potent and selective 5-HT2C agonists, are described. The key transformation involves ring opening of N-protected bicyclic sulfamidate (R)-hexahydro-3H-pyrazino[1,2-c][1,2,3]oxathiazine 1,1-dioxide with (4-halo-2-fluoropyridin-3-yl)lithiums or (3-bromo-5-fluoropyridin-4-yl)lithium. In situ hydrolyses of the resultant sulfamic acids and subsequent intramolecular nucleophilic aromatic substitutions (SNAr) produce the enantiopure tricycles. The two step procedure represents new methodology for the stereoselective syntheses of tetrahydronaphthyridines. 相似文献
997.
Xiaodan Ren Xiaoyi Yang Chaohua Guo Jianbo Li Quanhong Li 《Journal of Dispersion Science and Technology》2018,39(1):1-7
Sodium succinate sulfate (MAPEG1500-OSO3Na) was prepared using maleic anhydride (MA) and polyethylene glycols (PEG1500) as raw materials. The structure was characterized by Fourier transform infrared spectrometry (FTIR) and 1H-nuclear magnetic resonance (1H NMR). Its physicochemical properties, such as surface activity, adsorption behavior, spreading performance, and rheological property, were investigated by static/dynamic surface tension (DST) measurements, contact angle techniques, and rheological techniques at 25°C. Surface tension measurement for this surfactant is about 17?mN/m. The DST results indicated that the adsorption process is mixed diffusion-kinetic adsorption mechanism. The spreading measurement demonstrated that MAPEG1500-OSO3Na possessed an excellent spreading ability. Besides, the dispersion performances of MAPEG1500-OSO3Na on barium sulfate (BaSO4) particles under different conditions have been studied by the weighing method and transmission electron microscope (TEM). These results showed that there exist optimum pH value and added amount of MAPEG1500-OSO3Na corresponding to the highest dispersion rate. 相似文献
998.
Xue Li Kang Zhao Caiyin You Wensheng Linghu Feng Ye Mei Yu Ahmed Alsaedi Tasawar Hayat Hui Pan Jie Luo Xuemei Ren 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(3):509-522
The characterization of the nanocomposites (PANI@GO) by SEM, TEM, Raman and FT-IR indicated that the GO has been functionalized via PANI successfully. PANI@GO as a novel platform for the removal of Cd(II), Eu(III), Th(IV) and U(VI) from aqueous solutions, the uptake process was a spontaneous endothermic process, and is strongly dependent of pH but independent of ionic strength. The adsorption kinetic and isotherm were fitted well the Pseudo-second-order equation and Langmuir model. PANI@GO were recycled and re-used without significant loss of adsorption capacity, and real samples were also treated which showed that had little interference with the performance of it. 相似文献
999.
Bioactive glass-chitosan-alginate hybrid scaffolds were fabricated using BG sol as a dual function additive, which behaves as both bioactive inorganic phase to confer the bioactivity and cross-linker to improve the structural stability and mechanical properties. 相似文献
1000.
Photon affinity can serve as a probe for predicting the structures of protonated homodimers of amino acids. 相似文献