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921.
Exploring the native defects of zeolites is highly important for understanding the properties of zeolites, such as catalysis and optics. Here, ITQ-16 films were prepared via the secondary growth method in the presence of Ge atoms. Various intrinsic defects of ITQ-16 films were fully studied through photoluminescence and FTIR characterizations. It was found that both the as-synthesized and calcined ITQ-16 films displayed multicolor photoluminescence including ultraviolet, blue, green and red emissions by exciting upon appropriate wavelengths. The results indicate that Si-OH and non-bridging oxygen hole centers(NBOHCs) are responsible for the origin of green and red emissions at 540-800 nm, while according to a variety of emission bands of calcined ITQ-16 film, blue emission bands at around 446 and 462 nm are attributed to peroxy free radicals(≡SiO2·), ultraviolet emissions ranging from 250 nm to 450 nm are suggested originating from a singlet-to-triplet transition of two-fold-coordinated Si and Ge, respectively. 相似文献
922.
《Particuology》2016
SAPO-34 is one of the main catalysts used in the petrochemical industry. Various effective methods have been developed to synthesize SAPO-34 with optimal size and characteristics for such application. In the present study, SAPO-34 was synthesized using a dry gel method at high temperatures. Morpholine was used as an organic template. The products were characterized by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and gas sorption analysis. The results showed that application of the dry gel method at high temperatures successfully afforded a pure catalyst with high crystallinity. Small particles of less than 500 nm could be obtained within a short reaction time of 30 min. 相似文献
923.
The material properties of the rubber compounds, which are highly dependent on temperature, have a vital role in the tire behavior. A comprehensive study on the effect of the rubber properties on tire performance, for different temperatures, as well as different road conditions is required to adequately predict the performance of tires on ice.In this study, a theoretical model has been developed for the tire-ice interaction. The temperature changes obtained from the model are used to calculate the height of the water film created by the heat generated due to the friction force. Next, the viscous friction coefficient at the contact patch is obtained. By using the thermal balance equation at the contact patch, the dry friction is obtained. Knowing the friction coefficients for the dry and wet regions, the equivalent friction coefficient is calculated. The model has been validated using experimental results for three similar tires with different rubber compounds properties. The model developed can be used to predict the temperature changes at the contact patch, the tire friction force, the areas of wet and dry regions, the height of the water film for different ice temperatures, different normal load, etc. 相似文献
924.
925.
运用量子力学半经验分子轨道AM1方法,计算了金刚石(111)光滑表面上甲基合成金刚石薄膜的成核和生长反应过程的机理,给出反应体系和过渡态的能量.结果表明,甲基是金刚石(111)表面上金刚石成核和外延生长的有效生长成分. 相似文献
926.
The main objective of our research was development of a modified poly glutamic acid (PG) films by polylysine (PL) at different PL content (0, 2, 4 and 6%) as a microbioreactor to growth and protect Gamma-aminobutyric acid (GABA) producing bacteria. The addition of PL groups between the PG backbones was completely corroborated using FTIR analysis. Scanning electron micrographs confirmed the high changes in the microstructure of PG films by PL. Density, thickness, moisture content, L* (lightness), b*(yellowness-blueness), WI (whiteness index), opacity, and elongation at break were increased with increasing the PL content. Whereas ΔE (Total color difference) and tensile strength were decreased, simultaneously. The change of water vapor permeability and a* (redness-greenness) value of PG-PL were independent from PL content. The PG-PL films were active packaging material against food borne pathogens (i.e. Bacillus cereus and Escherichia coli). But they had not any side effects on viability of probiotic bacterium (i.e. Lactobacillus brevis G42) after drying process. It is inferable that PG-PL is a suitable candidate for the development of edible coating and film with high antimicrobial properties against food borne pathogen without any side effect on probiotic viability. 相似文献
927.
Jongyun Lee Minsoo Kim Kenji Watanabe Takashi Taniguchi Gil-Ho Lee Hu-Jong Lee 《Current Applied Physics》2019,19(3):251-255
We report on the fabrication and transport characteristics of van der Waals (vdW)-contacted planar Josephson junctions. In a device, two pieces of cleaved 2H-NbSe2 superconducting flakes and a monolayer graphene sheet serve as the superconducting electrodes and the normal-conducting spacer, respectively. A stack of NbSe2?graphene?hexagonal-boron-nitride (hBN) heterostructure with clean and flat interfaces was prepared by a dry transfer technique. The outermost hBN layer protected the NbSe2?graphene?NbSe2 Josephson junction from chemical contamination during the fabrication processes. The Josephson coupling was confirmed by a periodic modulation of the junction critical current in a perpendicular magnetic field. The temperature dependence of showed long and diffusive Josephson coupling characteristics. The temperature dependence of the superconducting gap, obtained from the multiple Andreev reflection features, followed the Bardeen?Cooper?Schrieffer (BCS) prediction. 相似文献
928.
929.
930.
Hyun-Jeong Nam Takeo Ebina Fujio Mizukami 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,346(1-3):158-163
Influences of exchangeable interlayer cations were investigated on self-standing film formability, film morphology, and properties of the clay films such as flexibility and gas barrier property. Ion-exchanged montmorillonite samples were prepared by a cation exchange from naturally bearing cation, mostly Na+, to Li+, Mg2+, Ca2+, Al3+, and Fe2+, 3+. Self-standing films were prepared from aqueous colloidal dispersions of these montmorillonite samples with no additives. The montmorillonite samples with monovalent or divalent cation formed flat self-standing films while the Al-montmorillonite sample produced a distorted film. The Fe-montmorillonite sample formed many separated reddish-brown rod-shaped pieces. Clay film microstructures were different with interlayer cations. The films with monovalent interlayer cations were constructed by the stacking of units with delicately waved thin clay sheets in the whole film, but other films show different morphologies between the upper side and lower side; the upper side is laminated with thin sheets; the lower side is laminated with large thick sheets.The self-standing films’ flexibility and gas barrier property differed according to the interlayer cations. These properties were good in cases of samples with monovalent cations. The innumerable short wave and sheet thinness are considered to foster good flexibility and gas barrier properties. The differences in film formability and properties of the films are attributable to different swellability among samples with different interlayer cations. The montmorillonite samples with monovalent cations swell sufficiently by water, but those with polyvalent cations swell poorly. In the latter case, clay crystals aggregate in water, then the aggregate grows into large particles, creating a film with large particles. 相似文献