Grafting of branched polymers onto nano-sized silica surface: Postgrafting of polymers with pendant isocyanate groups of polymer chain grafted onto nano-sized silica surface

To control the surface wettability of nano-sized silica surface, the postgrafting of hydrophilic and hydrophobic polymers to grafted polymer chains on the surface was investigated. Polymers having blocked isocyanate groups were successfully grafted onto nano-sized silica surface by the graft copolymerization of methyl methacrylate (MMA) with 2-(O-[1′-methylpropylideneamino]caboxyamino)ethyl methacrylate (MOIB) initiated by azo groups previously introduced onto the surface. The blocked isocyanate groups of poly(MMA-co-MOIB)-grafted silica were stable in a desiccator, but isocyanate groups were readily regenerated by heating at 150 °C. The hydrophilic polymers, such as poly(ethylene glycol) (PEG) and poly(ethyleneimine) (PEI), were postgrafted onto the poly(MMA-co-MOIB)-grafted silica by the reaction of functional groups of PEG and PEI with pendant isocyanate groups of poly(MMA-co-MOI)-grafted silica to give branched polymer-grafted silica. The percentage of grafting increased with increasing molecular weight of PEG, but the number of postgrafted chain decreased, because of steric hindrance. The hydrophobic polymers, such as poly(dimethylsiloxane) were also postgrafted onto poly(MMA-co-MOI)-grafted silica. It was found that the grafting of hydrophobic polymer and the postgrafting of hydrophilic polymer branches readily controls the wettability of silica surface to water.     

Kinetic Analyses of Solid-State Reactions with a Particle-Size Distribution

Kinetic analyses for the solid-state reactions of reactant particles in an assemblage with a particle-size distribution (PSD) have been reexamined for the reactions that proceed by the advance of the reaction interfaces inward toward the center of the individual reactant particles. The experimental kinetic curves for a particle assemblage are influenced by the existing PSD. It has been demonstrated that, even if PSD exists, a reliable activation energy E can be obtained from such overall kinetic curves by the empirical isothermal analysis without accounting for the PSD. The isoconversion methods, which enable us to determine the E value from the data points at a given fractional reaction of a series of experimental kinetic curves, are methodologically independent of the PSD. It is neccessary to incorporate the PSD into the kinetic equation to select an appropriate kinetic model and to evaluate the preexponential factor A . The method of kinetic calculation accounting for the PSD can be generalized, for the kinetic data under any thermal profiles, by extrapolating all the analytical conditions to infinite temperature. For the reaction characterized by the well-defined PSD and kinetic model function, the meaningful A value is obtained by the kinetic analysis at infinite temperature. Although the ability to discriminate the contracting geometry of the reaction interface in a single particle from the overall kinetic curve decreases with increasing PSD, the rate-controlling steps for the advance of the reaction interface, i.e., chemical reaction controlled or diffusion controlled, can be distinguised from each other even for the reactions with a fairly large PSD.     

Oxidation state of palladium as a factor controlling catalytic activity of Pd/SiO2–Al2O3 in propane combustion

The oxidation state of palladium on SiO₂–Al₂O₃ used for propane combustion was examined by XPS and XRD, and the correlation of the catalytic activity with the oxidation state of palladium was systematically studied. The propane conversion over 5 wt% Pd/SiO₂–Al₂O₃ was measured in the range 1.0≤S≤7.2 (S is defined as [O₂]/5[C₃H₈] based on stoichiometric ratio). The propane conversion strongly depended on the S value and reached the maximum at S=5.5. The oxidation state of palladium also changed with the S value; palladium particles were more oxidized under the reaction mixture of higher S value. On the sample used for the reaction at S=5.5, both of metallic palladium and palladium oxide were found. It is concluded that partially oxidized palladium which has optimum ratio of metallic palladium to palladium oxide shows the highest catalytic activity in propane combustion.     

木材经催化热分解向BTX和合成燃料的转化

以废木材生物质的有效利用为目的,使用粉粒流化床反应器,对3种木材进行了催化热分解实验,以4种催化效果不同的粒子作为流化床内的流化介质来考察催化热分解过程中介质颗粒、反应气体和热分解温度对产物分布的影响.木材的挥发性物质在700K时就已几乎分解出来,挥发性物质中的轻质芳香烃碳氢化合物（苯、甲苯、二甲苯和萘：BTXN）的收率随着热分解温度的升高而增加,1173K下达到3.1%（质量分数）,daf.在氢气气氛下,当作为流化介质颗粒Zn(3%,质量分数)/HZSM-5催化剂对木材进行催化热分解时,853K下可得到6.1%, daf的轻质芳香烃碳氢化合物的收率(BTX 5.5%,daf、萘0.6%,daf).而在活性很高的NiMo-A加氢催化剂下,在863K时,催化热分解产物几乎全为甲烷.     

Improvement of registration accuracy of a handheld augmented reality system for urban landscape simulation

The need for visual landscape assessment in large-scale projects for the evaluation of the effects of a particular project on the surrounding landscape has grown in recent years. Augmented reality (AR) has been considered for use as a landscape simulation system in which a landscape assessment object created by 3D models is included in the present surroundings. With the use of this system, the time and the cost needed to perform a 3DCG modeling of present surroundings, which is a major issue in virtual reality, are drastically reduced. This research presents the development of a 3D map-oriented handheld AR system that achieves geometric consistency using a 3D map to obtain position data instead of GPS, which has low position information accuracy, particularly in urban areas. The new system also features a gyroscope sensor to obtain posture data and a video camera to capture live video of the present surroundings. All these components are mounted in a smartphone and can be used for urban landscape assessment. Registration accuracy is evaluated to simulate an urban landscape from a short- to a long-range scale. The latter involves a distance of approximately 2000 m. The developed AR system enables users to simulate a landscape from multiple and long-distance viewpoints simultaneously and to walk around the viewpoint fields using only a smartphone. This result is the tolerance level of landscape assessment. In conclusion, the proposed method is evaluated as feasible and effective.     

Prediction of pressure–viscosity coefficient of lubricating oils based on sound velocity

The pressure–viscosity coefficient is an important parameter in tribology. Experimentally, it is calculated using the high‐pressure viscosity measurement. Also, the adiabatic bulk modulus is calculated using the sound velocity in the lubricating oil. Several lubricating oils are considered on the group basis such as traction oil, mineral oil, polyalphaolefin oil, perfluoropolyether oil and glycerol, depending on their molecular structure. Experimental pressure–viscosity coefficient is compared with the adiabatic bulk modulus. It is found that the pressure–viscosity coefficient increases exponentially with the adiabatic bulk modulus, and the relationship depends on the molecular structure of the lubricating oils. This study proposes two equations to predict the pressure–viscosity coefficient from the adiabatic bulk modulus based on sound velocity, one for the traction oil, and another for the paraffinic mineral oil and the polyalphaolefin oil. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of mesoporous titania nanoparticles with anatase frameworks and investigation of their photocatalytic performance

In this research paper, we synthesize various types of mesoporous titania nanoparticles (MTNs) with suitable surface area and pore size while creating anatase frameworks by applying hydrothermal treatment or calcination at different temperatures. Wide-angle XRD patterns and N2 adsorption-desorption isotherms reveal that the MTNs with crystallized anatase frameworks can be synthesized after an optimized hydrothermal treatment. In contrast, calcination of MTNs at high temperature caused the collapse of mesoporous structure, resulted in drastic reduction of the surface area of the MTNs. In addition, we investigate the photocatalytic activity of the prepared MTNs by measuring the degradation of methylene blue (MB). The results show that the reaction rates of the photocatalytic MB decomposition strongly depend on the degree of crystallinity in the MTNs frameworks and on the surface area of MTNs.     

Evaluation of delayed fracture property of outdoor-exposed high strength AISI 4135 steels

Delayed fracture properties of AISI 4135 high strength steels with 1490 and 1310 MPa of tensile strength, represented as B15 and B13, respectively, have been studied by means of slow strain rate test (SSRT) of notched bar specimens after outdoor exposure at rural and coastal areas. The exposed specimens were kept at humid medium before SSRT to reproduce active hydrogen entry influenced by the rust layer and to homogenize hydrogen distribution. The influences of exposure site and exposure time on fracture stress have been investigated. The susceptibility of B15 to delayed fracture was obviously higher than that of B13.     

Determining factors for anodic polarization curves of typical structural materials of boiling water reactors in high temperature – high purity water

In order to examine the anodic polarization characteristics of typical structural materials of boiling water reactors (BWRs), the anodic polarization curves of type 316L stainless steel (316L SS) and Alloy 182 were measured in deaerated high purity water at 553 K using the previously reported measurement method which was confirmed suitable for high temperature – high purity water. In order to specify which constituent element determines the dissolution characteristics of these materials, the anodic polarization curves of pure iron, pure nickel, and pure chromium were also surveyed. The anodic polarization curve of 316L SS was determined to have active, passive, and transpassive states which were the same as type 304 SS (304 SS) showed. But, Alloy 182 had different polarization characteristics especially near the corrosion potential as it had no active state. From comparison results of the polarization characteristics of these materials and their constituent elements, the corrosion characteristics of these materials were concluded to be mainly determined by the corrosion characteristics of chromium.     

Preparation and Characterization of Highly Fluorescent, Glutathione-coated Near Infrared Quantum Dots for in Vivo Fluorescence Imaging

Fluorescent probes that emit in the near-infrared (NIR, 700–1,300 nm) region are suitable as optical contrast agents for in vivo fluorescence imaging because of low scattering and absorption of the NIR light in tissues. Recently, NIR quantum dots (QDs) have become a new class of fluorescent materials that can be used for in vivo imaging. Compared with traditional organic fluorescent dyes, QDs have several unique advantages such as size- and composition-tunable emission, high brightness, narrow emission bands, large Stokes shifts, and high resistance to photobleaching. In this paper, we report a facile method for the preparation of highly fluorescent, water-soluble glutathione (GSH)-coated NIR QDs for in vivo imaging. GSH-coated NIR QDs (GSH-QDs) were prepared by surface modification of hydrophobic CdSeTe/CdS (core/shell) QDs. The hydrophobic surface of the CdSeTe/CdS QDs was exchanged with GSH in tetrahydrofuran-water. The resulting GSH-QDs were monodisperse particles and stable in PBS (phosphate buffered saline, pH = 7.4). The GSH-QDs (800 nm emission) were highly fluorescent in aqueous solutions (quantum yield = 22% in PBS buffer), and their hydrodynamic diameter was less than 10 nm, which is comparable to the size of proteins. The cellular uptake and viability for the GSH-QDs were examined using HeLa and HEK 293 cells. When the cells were incubated with aqueous solutions of the GSH-QDs (10 nM), the QDs were taken into the cells and distributed in the perinuclear region of both cells. After 12 hrs incubation of 4 nM of GSH-QDs, the viabilities of HeLa and HEK 293 cells were ca. 80 and 50%, respectively. As a biomedical utility of the GSH-QDs, in vivo NIR-fluorescence imaging of a lymph node in a mouse is presented.