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[en] Muonium has been directly detected over a range of temperatures and fields by transverse field μSR in different zeolites: 3A, 13X, USY, ZSM-5, and S-115 (a high-silica form of ZSM-5), as well as in silica gel. The polarizations determined from data at 75 and 150 G were independent of both field and temperature. The amounts of Mu seen vary from ∼20% to 40%, with a large missing fraction seen in every case, which may be partly due to slow Mu formation. There is also a fast Mu relaxation rate seen in all samples. This is the first direct observation of Mu in zeolites
[en] The electrochemical behavior of ferrocene moieties immobilized by covalent grafting on ordered mesoporous silica samples has been studied by cyclic voltammetry in aqueous medium using carbon paste electrodes modified with these solids. The functionalized silica samples were obtained using (3-(ferrocenylamide)propyl)triethoxysilane as the grafting agent. The results have been discussed in relation to the ferrocene content in the materials and compared to those obtained with non-ordered ferrocene-grafted silica gels. Well-defined voltammetric signals have been observed in spite of the insulating character of the mesoporous silica matrix and they were found to increase as a function of the ferrocene groups content in the material. They displayed a better stability upon continuous cycling potentials in comparison to those recorded with amorphous gels, suggesting a beneficial effect of the long-range structural order on the electron transfer processes in such confined media
[en] Highly transparent silica aerogel has been developed for a Cherenkov radiator in a RICH detector to be installed into the Belle forward end-cap apparatus. We have improved the aerogel optical properties for a wide range of refractive indices around 1.03-1.07. The parameters that control a synthesis process in the aerogel production were successfully optimized, and the obtained transmission length for this index range was almost doubled. A prototype was constructed using newly produced aerogel samples in order to carry out a test beam experiment, and a remarkable increase in the Cherenkov light yield was confirmed. The uniformity of refractive index in an aerogel block was examined using an X-ray tomography device and the deviation was found to be sufficiently small. Furthermore, the production of a monolithic aerogel consisting of two layers with different refractive indices is also described
[en] The complexes of europium(III) with 4,6-diacetylresorcinol (H2DAR) and a co-ligand (phen, bpy or 2,2'-bipyridine N,N'-dioxide (2,2'-bpyO2)) were in situ synthesized in silica matrix via a two-step gel process. The formation of complexes in silica gel was confirmed by the luminescence excitation spectra. The silica gels that contain in situ synthesized europium complexes exhibit the characteristic emission bands of the Eu(III). The results show that there are two ways to enhance the emission intensity of the Eu(III): (i) synthesize the complex in silica matrix and (ii) synthesize the complex with a co-ligand, which coordinates with Eu(III) in the composite system and can efficiently transfer the energy from 4,6-diacetylresorcinol to the Eu(III). The order of the luminescence intensities of the complexes is: Eu2(DAR)3(phen)2-(sol-gel) > Eu2(DAR)3(2,2'-bpyO2)2-(sol-gel) > Eu2(DAR)3 (bpy)2-(sol-gel) > Eu2(DAR)3-(sol-gel) > pure Eu2(DAR)3.4H2O
[en] Adsorption characteristics of germanium on silica gel were studied. Results show that the adsorption process can basically achieve the state of adsorption equilibrium within 15 min. The high-concentration HNO3 environment is favorable for the adsorption of Ge on silica gel. The adsorption rate is increasing with the system temperature. The concentration of Ge should be over 0.65 g/L. The adsorption process meets the Langmuir adsorption model and can also satisfy the Freundlich adsorption model. The adsorption process is an endothermic process, and the adsorption of Ge on silica gel can be best described by first order kinetics. (authors)
[en] Highlights: • GO-SiO2 rGO-SiO2 composites were prepared via chemical-thermal method. • HA-SiO2 and tHA-SiO2 composites were obtained by wet chemical techniques. • The morpho-structural characteristics of composites were evaluated and compared. • The rGO-SiO2 and tHA-SiO2 showed the highest antibacterial effect on E. Coli and S. Aureus.
[en] A highly-efficient bioconjugation protocol of bimetallic rod-nanotags interacted with bacterial anti-S. aureus-IgG has been firstly demonstrated. Controllable fabrication of multilayer plasmonic nanorod-array (MPNRA) can be successfully obtained by facet functionalization of nanorods stacked on an activated Si/SiO2 chip. Vancomycin coating of MPNRA is favorable to immobilize S. aureus bacteria via multiple hydrogen bonding interactions, i.e., peptidoglycan of the bacterial cell and carbonyl/amine groups of the vancomycin. Moreover, the bimetallic rod-nanotags can be assembled around MPNRA via a bacterial biointerface. Ultrasensitive SERS detection of S. aureus bacteria with limit-of-detection (LOD) can be achieved up to 17.8 cfu/mL via combination of rod-nanotag and multilayer plasmonic nanorod-array perpendicular a chip (MPNRA-perpendicular substrate), which could be ascribed to dual plasmonic enhancement from bioconjugated rod-nanotags aggregates and large-scaled plasmonic nanorod-array.
[en] It has been studied the dependence of amount, formation rate and radiation-chemical yield of molecular hydrogen obtained from radiation-heterogeneous decomposition of water on particle size of silica and filling rate (θ) of silica surface of water in the system of d=50, 100, 300/500 nm size silica + water absorbed in different filling rate of silica surface by the influence of gamma-quanta ( 60Co, P=18.17 rad/sec, T=300K). Maximum radiation-chemical yields of molecular hydrogen, corresponding to those particle sizes (d=50, 100, 300/500 nm) have got the values of G(H2)=10.85; 6.97 and 4.6 molecule/(100·eV), respectively. The researches conducted in different values (θ=0.5; 1; 2; 4; 10) of filling rate of particle surface of water in the system of nano-silica with d=50nm particle size + H2O show that, radiation-chemical yield of molecularhydrogen is directly proportional to filling rate of surface at θ<4, but there is observed saturation state at θ≥4. The mechanisms and explanations have been given below.
[en] Drying process directly affect in structure of the silica support for catalysts. Therefore,we herein prepared bimodal meso-macropore structure of silica by sol-gel method and investigated the silica support obtained from various drying techniques, namely, hot air drying(HA), microwave drying (MW) and freeze drying (FD)by means of BET and BJH N2-sorption, and SEM. The results showed a significant effect of drying technique on the textural properties of the dried bimodal porous silica support. In addition, it was found that freeze drying could enhance surface area of silica support with higher than 500 m2/g. (Author)