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1.
Covalent triazine frameworks (CTFs) have been recently employed for visible light-driven photocatalysis due to their unique optical and electronic properties. However, the usually highly hydrophobic nature of CTFs, which originates from their overall aromatic backbone, leads to limitations of CTFs for applications in aqueous media. In this study, we aim to extend the range of the application media of CTFs and design hybrid material of a CTF and mesoporous silica (SBA-15) for efficient photocatalysis in aqueous medium. A thiophene-containing CTF was directly synthesized in mesopores of SBA-15. Due to the high surface area and the added hydrophilic properties by silica, the hybrid material demonstrated excellent adsorption of organic molecules in water. This leads not only to high photocatalytic performance of the hybrid material for the degradation of organic dyes in water, but also for efficient photocatalysis in solvent-free and solid state. Furthermore, the reusability, stability and easy recovery of the hybrid material offers promising metal-free heterogeneous photocatalyst for broader applications in different reaction media. 相似文献
2.
C. W. Hill R. W. Gedridge T. J. Groshens G. B. Stringfellow L. P. Sad Wick 《Journal of Electronic Materials》1996,25(9):1434-1438
The low pressure decomposition of tertiarybutylbis(dimethylamino) phosphine, (t-Bu)P(NMe2)2, (TBBDMAP), has been studied on quartz and deposited GaP and InP surfaces. This new phosphorus precursor has been found to
pyrolyze on quartz surfaces at much lower temperatures than the related compounds tertiarybutylphosphine, (t-Bu)PH2, (TBP) and tris(dimethylamino)phosphorus, P(NMe2)3, (TDMAP). In contrast to the results obtained for TDMAP, GaP and InP surfaces decrease the decomposition temperature of TBBDMAP
only slightly. The TBBDMAP reaction products were dimethylamine, methylmethyleneimine, and isobutylene, consistent with previous
pyrolysis studies of TBP and TDMAP. 相似文献
3.
Fatma Belghith Hassan Kibeya Hassen Loukil Mohamed Ali Ben Ayed Nouri Masmoudi 《Journal of Real-Time Image Processing》2016,11(4):675-691
High-efficiency video coding is the latest standardization effort of the International Organization for Standardization and the International Telecommunication Union. This new standard adopts an exhaustive algorithm of decision based on a recursive quad-tree structured coding unit, prediction unit, and transform unit. Consequently, an important coding efficiency may be achieved. However, a significant computational complexity is resulted. To speed up the encoding process, efficient algorithms based on fast mode decision and optimized motion estimation were adopted in this paper. The aim was to reduce the complexity of the motion estimation algorithm by modifying its search pattern. Then, it was combined with a new fast mode decision algorithm to further improve the coding efficiency. Experimental results show a significant speedup in terms of encoding time and bit-rate saving with tolerable quality degradation. In fact, the proposed algorithm permits a main reduction that can reach up to 75 % in encoding time. This improvement is accompanied with an average PSNR loss of 0.12 dB and a decrease by 0.5 % in terms of bit-rate. 相似文献
4.
Gamal ElMasry Noha Morsy Salim Al-Rejaie Charfedinne Ayed Robert Linforth Ian Fisk 《International Journal of Food Science & Technology》2019,54(11):2983-2997
The aim of this study was to use gas chromatography-mass spectrometry (GC-MS) and APCI-MS techniques to detect adulteration in honey. The key volatile compounds in the headspace of the adulterated honey were marked by GC-MS and their representative fragment ions were utilised in scanning honey samples using the real-time APCI-MS system. The PLS models validated using independent data sets resulted in coefficient of the determination () of 0.97 and 0.96 and root mean square error in prediction (RMSEP) of 2.62 and 2.45 for the GC-MS and APCI-MS data sets respectively. The most efficient volatiles from GC-MS analysis and their corresponding fragment ions m/z from APCI-MS data analysis were then identified and used to develop new PLS models to predict the level of adulteration. The best PLS model gave of 0.95 and RMEP of 2.60% in the independent validation set indicating that the model was very accurate in predicting the level of adulteration. 相似文献
5.
Eman Sad Ashour Mohamad Yusof Bin Sulaiman Mohd Hafidz Ruslan Kamaruzzaman Sopian 《Nanoscale research letters》2013,8(1):466
Vertically aligned silicon nanowires have been synthesized by the chemical etching of silicon wafers. The influence of a hydrogenated amorphous silicon (a-Si:H) layer (shell) on top of a silicon nanowire (SiNW) solar cell has been investigated. The optical properties of a-Si:H/SiNWs and SiNWs are examined in terms of optical reflection and absorption properties. In the presence of the a-Si:H shell, 5.2% reflection ratio in the spectral range (250 to 1,000 nm) is achieved with a superior absorption property with an average over 87% of the incident light. In addition, the characteristics of the solar cell have been significantly improved, which exhibits higher open-circuit voltage, short-circuit current, and efficiency by more than 15%, 12%, and 37%, respectively, compared with planar SiNW solar cells. Based on the current–voltage measurements and morphology results, we show that the a-Si:H shell can passivate the defects generated by wet etching processes. 相似文献
6.
A 2D finite element analysis of the effect of numerical parameters on the reliability of Ti6Al4V machining modeling 总被引:1,自引:0,他引:1
Mariem Yaich Yessine Ayed Zoubeir Bouaziz Guénaël Germain 《Machining Science and Technology》2020,24(4):509-543
AbstractThe numerical analysis, based on the finite element modeling (FEM), presents nowadays an efficient computational tool. It allows a better understanding of several thermo-mechanical phenomena involved during the machining process. However, its reliability heavily depends on the accurate definition of the numerical model. In this regard, a FE analysis focused on the 2D modeling of the Ti6Al4V dry orthogonal machining was carried out in this study. The relevance of different numerical meshing approaches and finite elements topologies was studied. The effect of the friction coefficient on the numerical chip morphology, its geometry, the cutting and the feed forces was investigated. The adequacy of several compared adaptive meshing approaches, in terms of the modeling of severe contact conditions taking place around the cutting-edge radius, was underlined in the current study. However, numerical serrated chips, closer to the experimental ones, were only predicted when the pure Lagrangian formulation was adopted and a proper determination of the failure energy was carried out. The definition of different mesh topologies highlighted the efficiency of the 4-node quadrangular mesh, with a suitable edge length, in increasing the agreement with the experimental data, while reducing the computing times. 相似文献
7.
A. Z. El-Sonbati A. S. Al-Shihri A. A. El-Bindary 《Journal of Inorganic and Organometallic Polymers》2004,14(1):53-71
Polymer complexes derived from cinnamaldehyde and 2-substituted aniline with Cu(II), Pd(II), Pt(II), UO2(II), Rh(III), Ru(III), and Pd(IV) have been synthesized and characterized by IR, electronic, EPR, 1H-NMR, and 13C-NMR spectra, as well as by elemental analysis, thermogravimetry, and magnetic susceptibility measurements. The important bands in the IR spectra and the main 1H- and 13C-NMR signals are assigned and discussed in relation to molecular structure. The wavelengths of the principal electronic absorption peaks have been accounted for quantitatively in terms of crystal field theory and various parameters were evaluated. The complexes, [Ru(HL
n
)Cl3]
n
, are penta-coordinate; and, a trigonal-bipyramidal environment is commensurate for the Ru(III) ion. The presence of a coordinated water molecule in complex the Cu(II) complex (20) was demonstrated by thermogravimetry. The compounds, [N-(3-phenylacrylidene)-2-mercaptoaniline] (HL1) and cinnamaldehyde-2-aminophenol (HL2), act as monobasic and neutral bidentate ligands. The B-value suggests a strong covalency in the metal-ligand -bond. Tentative structures of the polymer complexes are proposed. 相似文献
8.
While the infrastructure in the United States is in need of large and immediate investment, the funds provided by public agencies are not nearly sufficient to face such a challenge. Build-operate-transfer (BOT) is a delivery/financing system that can be a solution to this problem. In this system, a private sponsor finances the design, construction, maintenance, and operation of a public project for a specified concession period, at the end of which it transfers ownership to the government agency, hopefully after recouping its costs and achieving profits. A questionnaire survey of large municipalities and state departments of transportation was conducted to determine the extent to which they are using BOT in their large projects, to investigate the implementation of BOT, and the reasons why some government agencies avoid using BOT. The findings indicate that very few agencies use BOT. The reasons why most do not use BOT were reported by the respondents to be the availability of proven alternatives and enough funds, the existence of political barriers, and resistance to change both on the part of government agencies and private sponsors. When government agencies and private sponsors explore the use of BOT, they should avoid the pitfalls perceived by the respondents in this study. 相似文献
9.
Nebojsa D. NIKOLIC Djendji Dj. VASTAG Vesna M. MAKSIMOVIC Goran BRANKOVIC 《中国有色金属学会会刊》2014,24(3):884-892
采用扫描电镜(SEM)研究在碱性电解液中通过恒电位沉积得到的铅粉。结果表明:铅晶体的形状主要取决于电沉积的过电位。通过欧姆控制步骤可以得到规则晶体。通过扩散控制得到的枝晶形状和电沉积的过电位有关系。不断增加的过电位导致枝晶的分枝从原始类型变成发达的三级分枝。基于该电解液属于络合铅电解液,解释具有强烈的(111)择优取向的枝晶分枝的形成原因。 相似文献
10.
This study investigates level set multiphase image segmentation by kernel mapping and piecewise constant modeling of the image data thereof. A kernel function maps implicitly the original data into data of a higher dimension so that the piecewise constant model becomes applicable. This leads to a flexible and effective alternative to complex modeling of the image data. The method uses an active curve objective functional with two terms: an original term which evaluates the deviation of the mapped image data within each segmentation region from the piecewise constant model and a classic length regularization term for smooth region boundaries. Functional minimization is carried out by iterations of two consecutive steps: 1) minimization with respect to the segmentation by curve evolution via Euler-Lagrange descent equations and 2) minimization with respect to the regions parameters via fixed point iterations. Using a common kernel function, this step amounts to a mean shift parameter update. We verified the effectiveness of the method by a quantitative and comparative performance evaluation over a large number of experiments on synthetic images, as well as experiments with a variety of real images such as medical, satellite, and natural images, as well as motion maps. 相似文献