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221.
Rooha Khurram Zaib Un Nisa Aroosa Javed Zhan Wang Mostafa A. Hussien 《Molecules (Basel, Switzerland)》2022,27(4)
This study describes the preparation of graphitic carbon nitride (g-C3N4), hematite (α-Fe2O3), and their g-C3N4/α-Fe2O3 heterostructure for the photocatalytic removal of methyl orange (MO) under visible light illumination. The facile hydrothermal approach was utilized for the preparation of the nanomaterials. Powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), and Brunauer–Emmett–Teller (BET) were carried out to study the physiochemical and optoelectronic properties of all the synthesized photocatalysts. Based on the X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance (DRS) results, an energy level diagram vs. SHE was established. The acquired results indicated that the nanocomposite exhibited a type-II heterojunction and degraded the MO dye by 97%. The degradation ability of the nanocomposite was higher than that of pristine g-C3N4 (41%) and α-Fe2O3 (30%) photocatalysts under 300 min of light irradiation. The formation of a type-II heterostructure with desirable band alignment and band edge positions for efficient interfacial charge carrier separation along with a larger specific surface area was collectively responsible for the higher photocatalytic efficiency of the g-C3N4/α-Fe2O3 nanocomposite. The mechanism of the nanocomposite was also studied through results obtained from UV-vis and XPS analyses. A reactive species trapping experiment confirmed the involvement of the superoxide radical anion (O2•−) as the key reactive oxygen species for MO removal. The degradation kinetics were also monitored, and the reaction was observed to be pseudo-first order. Moreover, the sustainability of the photocatalyst was also investigated. 相似文献
222.
ZHOU Zhan YU JianShe & CHEN YuMing School of Mathematics Information Science Guangzhou University Guangzhou China 《中国科学 数学(英文版)》2011,(1)
In this paper, a periodic difference equation with saturable nonlinearity is considered. Using the linking theorem in combination with periodic approximations, we establish sufficient conditions on the nonexistence and on the existence of homoclinic solutions. Our results not only solve an open problem proposed by Pankov, but also greatly improve some existing ones even for some special cases. 相似文献
223.
一个择一定理及对广义凸规划的应用 总被引:7,自引:1,他引:7
本文在实线性空间中得出了广义凸函数的择一定理 ,利用这一定理 ,我们获得广义凸规划的最优性条件 相似文献
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226.
Diffraction efficiency of grating plays an important role in output power of incoherent fiber laser beam combination. Through theoretic analysis and numerical simulations it has been proved that the diffraction efficiency would increase with the decrease of grating frequency and wavelength bandwidth. On the condition that the width of a fiber array is fixed at W=10 cm, an optimum grating frequency were numerically simulated as f=230 mm-1. Also an unequal interval method was proposed to improve the system efficiency of diffraction into 0.4293, which is higher than 0.3824 under the equal interval condition. 相似文献
227.
A new type of polyimide foam (PIF) was prepared and characterized based on a one‐pot process by the reaction of a first solution with different ratios of a second solution. The first solution was comprised of pyromellitic dianhydride (PMDA), N, N‐dimethyl formamide (DMF), methanol, water, surfactant, and catalysts, while the second solution contained polyaryl polymethylene isocyanate (PAPI). In the present study, the relationships among compositions, structures, and properties of PIFs were investigated. The results indicated that with the increase in the weight ratio of PAPI/(first solution), the foaming degrees of PIFs increased from 10.14 to 10.52 times and the apparent densities before postcure decreased from 15.96 to 14.51 kg/m3. The open cell contents, average sound absorption coefficients, and average cellular diameters of PIFs after postcure increased with increase in the weight ratio of PAPI/(first solution). The glass transition temperatures (Tg) of PIFs after postcure first increased from 287 to 299°C, then decreased to 292°C, and the 5% weight loss temperatures and 10% weight loss temperatures presented the same trend as well. The compressive and flatwise tensile properties scaled very well with the relative densities of the foams after postcure, with the highest compressive strength of 0.03 MPa and the highest flatwise tensile strength of 0.15 MPa. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
228.
Zhan Yu Lee Chuin Chen Rosa Erra‐Balsells Hiroshi Nonami Kenzo Hiraoka 《Rapid communications in mass spectrometry : RCM》2010,24(11):1507-1513
Probe electrospray ionization (PESI) is a modified version of the electrospray ionization (ESI), where the capillary for sampling and spraying is replaced by a solid needle. High tolerance to salts and direct ambient sampling are major advantages of PESI compared with conventional ESI. In this study, PESI‐MS was used to monitor some biological and chemical reactions in real‐time, such as acid‐induced protein denaturation, hydrogen/deuterium exchange (HDX) of peptides, and Schiff base formation. By using PESI‐MS, time‐resolved mass spectra and ion chromatograms can be obtained reproducibly. Real‐time PESI‐MS monitoring can give direct and detailed information on each chemical species taking part in reactions, and this is valuable for a better understanding of the whole reaction process and for the optimization of reaction parameters. PESI‐MS can be considered as a potential tool for real‐time reaction monitoring due to its simplicity in instrumental setup, direct sampling with minimum sample preparation and low sample consumption. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
229.
Xiao-Yong Zheng Cai-Hong Zhan Shu-Guang Zhang Yun-Long Feng 《Journal of chemical crystallography》2011,41(4):587-590
Abstract
The new complex with flexible heterocyclic carboxylate ligand, [Ba(HL−)2(H2O)3]·H2O (H2L = 1-(4-Hydroxyphenyl)-5-thioacetatetetrazole), were synthesized and structurally determined by X-ray diffraction analysis. The complex belongs to the monoclinic system, space group C2/c. The center Ba(II) is nine-coordinated by six carboxylate oxygen atoms from four HL-ligands and three water molecules in a distorted monocapped square trans-prism geometry. The ligand serves as a bridge to link two adjacent Ba(II) atoms into a chain structure which are further assembled into the final three-dimensional supramolecular architecture with microporous open channel via hydrogen bonds. 相似文献230.
Baoyong Zhang James Lam Shengyuan Xu Zhan Shu 《Nonlinear Analysis: Real World Applications》2010,11(3):1963-1976
This paper is concerned with the problem of absolute exponential stability analysis for a class of continuous-time systems with sector-bounded nonlinearities and interval time-varying delays. Absolute exponential stability criteria, which depend not only on the delay range but also on the decay rate, are derived by using a novel Lyapunov functional. These criteria are expressed in the form of linear matrix inequalities (LMIs) and they can easily be checked. By solving these LMIs, estimates of the exponential decay rate and decay coefficient are obtained. A numerical example is provided to demonstrate the effectiveness of the proposed method. 相似文献