氮掺杂石墨烯负载的硫化镉空心球纳米复合材料的光催化性能

通过无模板法一步合成了一种新型N掺杂石墨烯负载的CdS空心球复合材料. 采用X射线衍射、透射电镜、红外光谱、紫外-可见光谱、N₂吸附-脱附、荧光光谱和X射线光电子能谱等技术对该材料进行了表征, 并在可见光照射下测试了其在降解亚甲基蓝和水杨酸中的光催化性能. 结果表明, 相对于氧化石墨烯负载硫化镉空心球和单独的硫化镉空心球, 氮掺杂石墨烯负载的硫化镉空心球具有更高的光催化活性和稳定性. 这是由于氮掺杂的石墨烯能充当优异的电子受体和传输体, 从而抑制了载流子的复合. 另外发现, 羟基自由基是可见光下降解亚甲基蓝的主要活性物种.     

改进型溶胶-凝胶法制备粒径可调高染料吸附量TiO2微球及其在染敏电池光散射层中的应用

利用改进型的溶胶-凝胶法,制得了由锐钛矿相纳米颗粒组成的TiO2多孔微纳小球。通过调节前驱物浓度,合成出粒径可控的尺寸分别为100,175,225,475 nm的TiO2微纳小球,并通过电泳沉积法将合成出的小球作为光散射层引入到染料敏化太阳电池(DSSC)中。由于这种微纳小球在具备良好的光散射性能的同时也具备较高的染料吸附量,因此相较于基于纳米颗粒的单层结构的DSSC拥有更高的光电转换效率。通过比较分析,粒径尺寸为475 nm的微球作为光散射层的DSSC光电转换效率可以达到6.3%,较之于基于纳米颗粒的DSSC提高了30%。     

The Synthesis and Application of the Mesoporous Molecular Sieves MCM-41 — A Review

We report a “delayed neutralization” process for the preparation of highly-ordered aluminosilicate MCM-41 molecular sieves with high thermal and hydrothermal stability, and sharp pore size distribution. However, the structural order and pore size are dependent on the carbon chain length. In the mixture surfactant systems, the pore size of the MCM-41 materials could be fine-tuned. The pore size can be extended from 2.5 to 4.5 nm by adding a suitable amount of hydrocarbons. The tubular morphology of the MCM-41 material of 0.3 to 10 micrometers diameter, where the wall consists of coaxial cylindrical pores of nanometers MCM-41, can be obtained by careful control of the surfactant-water content and the rate of condensation of silica. An optimum condition for automatic synthesis of the hierarchical TWT structure has been accomplished. The addition of 1-alkanols as cosurfactant would not only improve the order of the MCM-41 hexagonal structure but also promote the formation of micrometer-sized hierarchical materials, for example: tubules-within-tubule and uniform-sized hollow spheres of diameter 5.0 ± 1.0 μm. However, the inside of the micron spheres has intricate structures possessing various topological genus ranks. The MCM-41 is a good supporter for Molybdenum oxide catalysts. The rate of deactivation in the catalytic reaction of ethyl-benzene dehydrogenation to styrene increases in the order: M_T < M_P < SiO₂. The physically mixed samples have higher catalytic activity than impregnated ones.     

Fabrication linalool-functionalized hollow mesoporous silica spheres nanoparticles for efficiently enhance bactericidal activity

To develop a novel food preservation technology for efficiently enhance bactericidal activity in a long term, hollow mesoporous silica spheres (HMSS) with regular nanostructures were applied to encapsulate natural organic antimicrobial agents. The chemical structures, morphologies and thermal stabilities of linalool, HMSS and linalool-functionalized hollow mesoporous silica spheres (L-HMSS) nanoparticles were evaluated by polarimeter, field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), fourier transform infrared (FT-IR), thermal gravimetric analyzer (TGA), nitrogen adsorption-desorption, zeta potential and small angle X-ray diffraction (SXRD). The results show that the linalool was successfully introduced into the cavities of HMSS, and the inorganic host exhibited a high loading capacity of about 1500 mg/g. In addition, after 48 h of incubation, the minimum bactericidal concentrations (MBC) of L-HMSS against Escherichia coli (E. coli), Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes) were decreased to be 4 (< 5) mg/mL and 8 (< 10) mg/mL, respectively. These results revealed linalool-functionalized hollow mesoporous spheres could efficiently improve the bactericidal activities of the organic component. Furthermore, SEM images clearly showed that L-HMSS indeed had an extremely inhibitory effect against gram-negative (E. coli) and gram-positive (S. aureus) by breaking the structure of the cell membrane. This research is of great significance in the application of linalool in nano-delivery system as well as food industry.     

The Effect of the Modification of Carbon Spheres with ZnCl2 on the Adsorption Properties towards CO2

Zinc chloride and potassium oxalate are often applied as activating agents for carbon materials. In this work, we present the preparation of ZnO/carbon spheres composites using resorcinol-formaldehyde resin as a carbon source in a solvothermal reactor heated with microwaves. Zinc chloride as a zinc oxide source and potassium oxalate as an activating agent were applied. The effect of their addition and preparation conditions on the adsorption properties towards carbon dioxide at 0 °C and 25 °C were investigated. Additionally, for all tested sorbents, the CO₂ sorption tests at 40 °C, carried out utilizing a thermobalance, confirmed the trend of sorption capacity measured at 0 and 25 °C. Furthermore, the sample activated using potassium oxalate and modified using zinc chloride (a carbon-to-zinc ratio equal to 10:1) displayed not only a high CO₂ adsorption capacity (2.69 mmol CO₂/g at 40 °C) but also exhibited a stable performance during the consecutive multicycle adsorption–desorption process.     

球面稳定同伦元素α1β1βs的非平凡性

决定球面稳定同伦群是同伦论中的核心问题之一,是非常重要的．该文证明:球面稳定同伦元素α1β1βs是一个阶为p的非平凡元素,其中p≥5是任意奇素数,1≤s相似文献   

球面稳定同伦群中的一个新元素族$b_1g_0\tilde{\gamma}_s$

设$p\geq 7$素数,$A$为模$p$的Steenrod代数. 我们利用Adams谱序列证明了球面稳定同伦群$\pi_{\ast}S$中,存在由$b_1g_0\tilde{\gamma}_{s}\in Ext_A^{s+4,(s+1)p^2q+spq+sq+s-3}(Z_p,Z_p)$所表示的新的非平凡元素族,其中$q=2(p-1)$, $3\leq s相似文献   

Nanometer Calibration Particles: What is Available and What is Needed?

Information on available polystyrene calibration spheres is presented regarding the particle diameter, uncertainty in the size, and the width of the size distribution for particles in a size range between 20 and 100nm. The use of differential mobility analysis for measuring the single primary calibration standard in this size range, 100nm NIST Standard Reference Material®1963, is described along with the key factors in the uncertainty assessment. The issues of differences between international standards and traceability to the NIST Standard are presented. The lack of suitable polystyrene spheres in the 20–40nm size range will be discussed in terms of measurement uncertainty and width of the size distributions. Results on characterizing a new class of molecular particles known as dendrimers will be described and the possibilities of using these as size calibration standards for the size range from 3 to 15nm will be discussed.     

Improved solution of displacements due to a compacting reservoir over a rigid basement

Geertsma’s analytical method is often used to compute strain and stress changes around a compacting geological reservoir. The present work extends Geertsma’s solution by adding a rigid layer beneath the compacting reservoir. Analytical formulae are presented for all the components of displacement of a point in the subsurface. Our derivation includes the correction of an error found in the paper written by Sharma in 1956.     

Cascaded electron transition in CuWO_4/CdS/CDs heterostructure accelerating charge separation towards enhanced photocatalytic activity

CuWO_4,as an n-type oxide semiconductor with a bandgap of 2.2 eV,has stimulated enormous interest as a potential broad-spectrum-active photocatalyst for environmental pollution remediations.However,rapid charge recombination greatly hinders its practical applications.Herein,we present a cascaded electron transition pathway in a ternary heterostructure consisting of CdS quantum dots,carbon dots(CDs) and CuWO_4 hollow spheres,which proves to greatly facilitate the photogenerated electron-hole separation,and eventually boosts the degradation efficiency of phenol and congo red by 100% and 46%compared to bare CuWO_4.The enhanced performance of the CuWO_4/CdS/CDs heterostructure mainly originates from the unidirectional electron migration from CdS to CuWO_4 and then to the organics through CDs.This work elucidates the electron transfer kinetics in multi-phase system and provides a new design paradigm for optimizing the properties of CuWO_4 based photocatalysts.