On the Catalytic Activity of Sn Monomers and Dimers at Graphene Edges and the Synchronized Edge Dependence of Diffusing Atoms in Sn Dimers

In this study, in situ transmission electron microscopy is performed to study the interaction between single (monomer) and paired (dimer) Sn atoms at graphene edges. The results reveal that a single Sn atom can catalyze both the growth and etching of graphene by the addition and removal of C atoms respectively. Additionally, the frequencies of the energetically favorable configurations of an Sn atom at a graphene edge, calculated using density functional theory calculations, are compared with experimental observations and are found to be in good agreement. The remarkable dynamic processes of binary atoms (dimers) are also investigated and is the first such study to the best of the knowledge. Dimer diffusion along the graphene edges depends on the graphene edge termination. Atom pairs (dimers) involving an armchair configuration tend to diffuse with a synchronized shuffling (step-wise shift) action, while dimer diffusion at zigzag edge terminations show a strong propensity to collapse the dimer with each atom diffusing in opposite directions (monomer formation). Moreover, the data reveals the role of C feedstock availability on the choice a single Sn atom makes in terms of graphene growth or etching. This study advances the understanding single atom catalytic activity at graphene edges.     

Kinetics of reversible addition–fragmentation transfer (RAFT) miniemulsion polymerization of styrene using dibenzyl trithiocarbonate as RAFT reagent and costabilizer

The roles of dibenzyl trithiocarbonate (DBTTC) as both costabilizer and reversible addition–fragmentation transfer (RAFT) reagent in RAFT miniemulsion polymerizations of styrene were investigated. The effectiveness of DBTTC costabilizer in retarding Ostwald ripening involved in the storage stability of miniemulsion is comparable to that of conventional low‐molecular‐weight costabilizers such as cetyl alcohol, but inferior to that of hexadecane. The major variables chosen for studying kinetics of RAFT miniemulsion polymerizations include the type of initiators and levels of DBTTC and surfactant. At a constant level of DBTTC, the rate of polymerization for benzoyl peroxide (BPO)‐initiated polymerization is slower than that for sodium persulfate (SPS)‐initiated polymerization. Furthermore, the polymerization rate decreases with increasing level of DBTTC for polymerizations initiated by BPO (or SPS). It is the monomer droplet nucleation that governs BPO‐initiated polymerizations. In contrast, for SPS‐initiated polymerizations, the probability for homogeneous nucleation to take place is greatly increased, especially for polymerizations with lower levels of DBTTC and higher levels of surfactant. © 2015 Society of Chemical Industry     

Facile growth of novel morphology correlated Ag/Co-doped ZnO nanowire/flake-like composites for superior photoelectrochemical water splitting activity

In this paper, novel morphology correlation between silver nanowires (AgNWs) and cobalt (Co)-doped ZnO (Co-ZnO) flake-like thin films (nanowire/flake-like) has been proposed for enhanced photoelectrochemical (PEC) water splitting activity. Here in, high-quality AgNWs/Co-ZnO heterostructures enabled superior visible light water splitting activity compared to the pure ZnO and AgNWs/ZnO. To address the strategic effect of AgNWs coupling and transition metal (Co-2?at%) doping into the ZnO host lattice, we have carried out the X-ray diffraction, field emission scanning microscopy, X-ray photoelectron spectroscopy, UV–Vis transmittance, water contact angle and PEC analyses. In this way, PEC water splitting activity was mainly examined by linear sweep voltammetry (I-V), amperometric I-t and photoconversion efficiency (η) studies. The experimental results provide clear evidence of morphology correlation between AgNWs and Co-ZnO flake-like structures for strong visible light absorption. Specifically, AgNWs/Co-ZnO composites exhibited significant enhancement in the photocurrent density (7.0?×?10^?4 A/cm²) than AgNWs/ZnO (3.2?×?10^?4 A/cm²) and pure ZnO (1.5?×?10^?6 A/cm²). As a result, detailed AgNWs/Co-ZnO geometry has great potential for photoconversion efficiency (0.73%). In a word, the merits of controllable AgNWs/Co-ZnO heterostructure are proposed to improve the visible light harvesting and charge carrier generation for energy conversion devices.     

Solving distribution problems in content-based recommendation system with gaussian mixture model

Applied Intelligence - Recommendation systems play an important role in boosting purchasing consumption for many manufacturers by helping consumers find the most appropriate items. Furthermore,...     

Some chemical properties of hazelnut husk and its suitability for particleboard production

Hazelnut husk is a renewable natural resource that has not industrial utilization yet. The objective of this study was to examine some chemical properties (holocellulose, cellulose, lignin and ash contents, alcohol–benzene, hot and cold water solubility and solubility in dilute alkali (1% NaOH)) of hazelnut husk and to evaluate its suitability to produce composite panels. For this study, particleboards were produced using hazelnut husk as an alternative raw material for the forest products industry. Two panel density levels (0.6 and 0.7 g/cm³) and three types of resins (urea-formaldehyde (UF), phenol formaldehyde (PF), melamine-formaldehyde (MUF)) were selected as treatments. The findings indicated that hazelnut husk waste is a valuable renewable natural resource for particleboard production and could be utilized as a substitute for wood in board production. Its shortcomings, such as higher water absorption and thickness swelling could easily be controlled by adding water repellent chemicals in production. The bending and the internal bond strength properties of the hazelnut husk boards produced met the requirement for the general purpose product standards (TS-EN 312-2) at 0.70 g/cm³ density.     

Global–local interaction and its impact on cities

This introduction paper to the special issue of Journal of Housing and the Built Environment explores the interrelations among ‘globalization, urban systems, and local development’ by focusing on global-local interactions and their impacts on cities. After tackling the idea that globalization is about the spread of capitalism and capitalist principles throughout the world, the paper introduces the questions that each article intends to answer. The issues addressed by these questions were grouped under four headings: global versus local forces and urban change; urban systems within the global network of cities; globalization and property markets; and governance of globalizing cities.     

Influence of Serum and Hypoxia on Incorporation of [14C]-d-Glucose or [14C]-l-Glutamine into Lipids and Lactate in Murine Glioblastoma Cells

Glucose and glutamine are essential energy metabolites for brain tumor growth and survival under both normoxic and hypoxic conditions. Both metabolites can contribute their carbons to lipid biosynthesis. We used uniformly labeled [¹⁴C]‐U‐d ‐glucose and [¹⁴C]‐U‐l ‐glutamine to examine the profile of de novo lipid biosynthesis in the VM‐M3 murine glioblastoma cells. The major lipids synthesized included phosphatidylcholine (PtdCho), phosphatidylethanolamine (EtnGpl), phosphatidylinositol (PtdIns), phosphatidylserine (PtdSer), sphingomyelin (CerP Cho), bis(monoacylglycero)phosphate (BMP)/phosphatidic acid (PtdOH), cholesterol (C), cardiolipin (Ptd₂Gro), and gangliosides. Endogenous lipid synthesis, using either glucose or glutamine, was greater in media without fetal bovine serum (FBS) than in media containing 10 % FBS under normoxia. De novo lipid synthesis was greater using glucose carbons than glutamine carbons under normoxia. The reverse was observed for most lipids under hypoxia suggesting an attenuation of glucose entering the TCA cycle. Lactate was produced largely from glucose carbons with minimal lactate derived from glutamine under either normoxia or hypoxia. Accumulation of triacylglycerols (TAG), containing mostly saturated and mono‐unsaturated fatty acids, was observed under hypoxia using carbons from either glucose or glutamine. The data show that the incorporation of labeled glucose and glutamine into most synthesized lipids was dependent on the type of growth environment, and that the VM‐M3 glioblastoma cells could acquire lipids, especially cholesterol, from the external environment for growth and proliferation.     

连铸板坯质量在线诊断系统的应用

通过对铸坯质量缺陷的理论预测结果与实际检测结果之间的对比分析,对理论模型的相关重要参数进行了修正,以提高其预测的准确性,从而为生产现场提供重要的判断依据。