A combinative method with reactive sputtering deposition and selenization technique was applied to prepare superconducting FeSex films on LaAlO3 substrates successfully. The influence of selenizing temperature on film components was studied. FeSe0.96 and FeSe films had similar and good performances in transport measurement but little difference in magnetic property. The critical onset temperature got to 11.2 K and Tc,0 got to 4 K approximately. X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy were used to analyze the ratio of constituents and morphology of several selenized films. FeSex film had a porous structure on surface and no well preferred orientation, which were confirmed to have little influence on superconducting properties. 相似文献
Tetrafluoromethane (CF4), the simplest perfluorocarbon (PFC), has the potential to exacerbate global warming. Catalytic hydrolysis is a viable method to degrade CF4, but fluorine poisoning severely restricts both the catalytic performance and catalyst lifetime. In this study, Ga is introduced to effectively assists the defluorination of poisoned Al active sites, leading to highly efficient CF4 decomposition at 600 °C with a catalytic lifetime exceeding 1,000 hours. 27Al and 71Ga magic-angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) showed that the introduced Ga exists as tetracoordinated Ga sites (GaIV), which readily dissociate water to form Ga−OH. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density function theory (DFT) calculations confirmed that Ga−OH assists the defluorination of poisoned Al active sites via a dehydration-like process. As a result, the Ga/Al2O3 catalyst achieved 100 % CF4 decomposition keeping an ultra-long catalytic lifetime and outperforming reported results. This work proposes a new approach for efficient and long-term CF4 decomposition by promoting the regeneration of active sites. 相似文献
In our experimental work on carbon nanotubes synthesis, the influence of pre-treatment and reaction temperature conditions
over Fe catalyst loaded on low-cost activated carbon (AC) in the catalytic chemical vapor deposition of methane was studied.
Catalyst with the metal concentration of 5 mass % calcined at 350°C and reduced at 450°C was effective in CH4 decomposition giving 98 % conversions. TEM images showed that thin multi-walled carbon nanotubes (MWNTs) with the average
internal diameter of ∼ 8 nm and the wall thickness of ∼ 2.5 nm were obtained over unreduced Fe/AC catalyst at the reaction
temperature of 850°C. On the other hand, broader filamentous nanostructures with the diameter of ∼ 22 nm and the wall thickness
of ∼ 3.72 nm were observed over reduced catalyst. 相似文献
Neutron activation analysis (NAA) and dual energy X-ray absorptiometry (DEXA) have been used to study the effects of different
calcium supplements on osteoporosis, including calcium carbonate, calcium threonate, calcium gluconate, calcium lactate, calcium
acetate and a traditional Chinese medicine. Animal test results showed that calcium carbonate, calcium gluconate, calcium
acetate and the Chinese medicine notably increased osteoporotic rat's femoral bone mineral density (BMD). Also, calcium carbonate,
calcium acetate and the Chinese medicine significantly increased osteoporotic rat's vertebral BMD. But calcium L-threonate
and calcium lactate had no such effects. Calcium gluconate, calcium acetate and the Chinese medicine improved the bone mechanical
intensity of osteoporotic rats. The results of NAA showed that the loss of elements in spongy bones was more seriously than
that in compact bone and was difficult to be improved.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
Abstract
Passive air samplers (polyurethane foam disks) were deployed at 25 urban sites and 66 rural sites over the period of July
to October 2005, partly between October 2005 and January 2006 for about 120 days across China, and analyzed for extractable
organo-chlorine /-bromine /-iodine (EOCl/EOBr/EOI) and polychlorinated biphenyls (PCBs) using hybrid neutron activation analysis
(NAA) combined with gas chromatographymass spectrometry (GC-MS). The average concentration of EOCl, EOBr, EOI and ΣPCBs among
all the sites were 173.7, 3.5, 1.0 and 0.74 ng/d, respectively. Higher values of EOCl/Br/I and PCBs were detected in the areas
of high usage and high emission, which were linked to relatively high-income areas in China, while lower in the west ill-developed
region of China, which indicated that these pollutants mainly came from industrial pollution. Higher EOCl contents in traffic
areas stated that the exhaust emission from vehicle was another main source of organochlorines in the air. The relative proportions
of the known organochlorines (84 PCB congeners) to total EOCl were 0.02–3.0%, which implied that most of EOCl measured in
air were unknown. 相似文献
Isoliquiritigenin, a chalcone found in licorice root and many other plants, has shown potential antioxidant, estrogenic and antitumor activities. The present study was to investigate urinary metabolism of isoliquiritigenin in Wistar rats by ultra-high pressure liquid chromatography coupled to electrospray ionization TOF–MS (UHPLC–TOF–MS)-based xenometabolomics. Urine samples were collected before and after oral administration of isoliquiritigenin, and analyzed by UHPLC–TOF–MS. After deconvolution, the resulting data matrices were subjected to multivariate data analysis. Projection to latent structures discriminant analysis was performed to screen the metabolites. Fifteen urinary metabolites of isoliquiritigenin were screened out and 13 of them were further identified by Agilent MassHunter Software. The results of this work show that UHPLC–TOF–MS-based xenometabolomics was able to comprehensively identify the metabolites of phytochemicals and may represent a valuable tool for monitoring the food consumption.
Research on Chemical Intermediates - Pyrolysis Gas Chromatography/Mass Spectroscopy (Py-GC/MS) was used to investigate the catalytic pyrolysis of waste wood chip. Two different mesoporous... 相似文献
The accuracy of the solution of the fundamental space-filling mode of photonic crystal fibers by scalar and vectorial analytical approaches and its effect on the effective index models are investigated. Using a plane wave method as a benchmark, we show that the optimal choice of the radius of the equivalent circular unit cell used in the approximations is different for the two approaches and this value has a great effect on the accuracy of the solution of the fundamental space-filling mode. We also show that the vectorial approach with a properly defined value of the radius is highly accurate over a wide parameter range, whereas the scalar approach causes the main error in the scalar effective index model. We also confirm that a fully vectorial effective index model is accurate and efficient in the case of photonic crystal fibers with large air filling fractions. PACS 42.25.Bs; 42.70.Qs; 42.81.Qb 相似文献
This paper devotes to analyzing deconvolution algorithms based on wavelet frame approaches, which has already appeared in
Chan et al. (SIAM J. Sci. Comput. 24(4), 1408–1432, 2003; Appl. Comput. Hormon. Anal. 17, 91–115, 2004a; Int. J. Imaging Syst. Technol. 14, 91–104, 2004b) as wavelet frame based high resolution image reconstruction methods. We first give a complete formulation
of deconvolution in terms of multiresolution analysis and its approximation, which completes the formulation given in Chan
et al. (SIAM J. Sci. Comput. 24(4), 1408–1432, 2003; Appl. Comput. Hormon. Anal. 17, 91–115, 2004a; Int. J. Imaging Syst. Technol. 14, 91–104, 2004b). This formulation converts deconvolution to a problem of filling the missing coefficients of wavelet frames
which satisfy certain minimization properties. These missing coefficients are recovered iteratively together with a built-in
denoising scheme that removes noise in the data set such that noise in the data will not blow up while iterating. This approach
has already been proven to be efficient in solving various problems in high resolution image reconstructions as shown by the
simulation results given in Chan et al. (SIAM J. Sci. Comput. 24(4), 1408–1432, 2003; Appl. Comput. Hormon. Anal. 17, 91–115, 2004a; Int. J. Imaging Syst. Technol. 14, 91–104, 2004b). However, an analysis of convergence as well as the stability of algorithms and the minimization properties
of solutions were absent in those papers. This paper is to establish the theoretical foundation of this wavelet frame approach.
In particular, a proof of convergence, an analysis of the stability of algorithms and a study of the minimization property
of solutions are given. 相似文献