固定在氧扩散膜表面的TiO2光催化膜

本文提出用氧扩散膜作ＴｉＯ２光催化膜的载体。介绍了氧扩散膜的制备及ＴｉＯ２在氧扩散膜表面的固定方法,ＴｉＯ２光催化膜的表面形态与微结构,不同条件下光催化分解草 的速度。     

两种新型阳离子吲哚啉螺吡喃的合成,表征和光致变色性质的研究

螺吡喃是一类重要的光致变色化合物．螺吡喃的正向光致变色是指在紫外光照下,螺吡喃分子的Ｃ—Ｏ键异裂,由闭环无色体（ＳＰ）可逆地变成开环有色体（ＭＣ）．所形成的有色体可以在暗条件下热致褪色或在可见光照下褪成无色体（示意图１）．它的逆向光致变色是指某一类螺...     

Enhancement of detecting defects in pipes with focusing techniques

Ultrasonic guided waves have been widely utilized for long range inspection of structures such as oil and petrochemical pipes. However, weldments, support, insulation, and attenuation make it difficult to examine pipe-like structures. In order to overcome such difficulties, it is desired to focus ultrasonic guided wave at the area under interrogation. In this paper, we discuss two focusing techniques: angular profile tuning and signal based focusing. The angular profile tuning approach relies on a theoretical prediction of pressure field of ultrasonic guided wave produced by an ultrasonic transducer mounted on the pipe. And, the signal based focusing is focusing ultrasonic guided waves using cross-correlation analysis. To compare the performance of these two techniques, non-axisymmetric guided waves are focused to abnormalities such as a through-wall hole and a circumferential notch, using an ultrasonic guided wave array system that has been specially fabricated for this purpose. The advantages and limitations of these two focusing techniques are addressed.     

An investigation into material-induced surface roughness in ultra-precision milling

This paper presents a theoretical and experimental investigation into the effect of the workpiece material on surface roughness in the ultra-precision milling process. The influences of material swelling and tool-tip vibration on surface generation in ultra-precision raster milling are studied. A new method is proposed to characterize material-induced surface roughness on the raster-milled surface. A new parameter is defined to characterize the extent of surface roughness profile distortion induced by the materials being cut. An experiment is conducted to compare the proposed method with surface roughness parameters and power spectrum density analysis method by machining three different workpiece materials. The results show that the presence of elastic recovery improves the surface finish in ultra-precision raster milling and that, among the three materials being cut in the experiment, aluminum bronze has the greatest influence on surface finish due to its highest elastic recovery rate and hardness. The results also show that, in the case of faster feed rates, the proposed method more efficiently characterizes material-induced surface roughness.     

Comparison of particle-phase polycyclic aromatic hydrocarbons and their variability causes in the ambient air in Ho Chi Minh City, Vietnam and in Osaka, Japan, during 2005-2006

A comparative study of polycyclic aromatic hydrocarbons (PAHs) associated with particulate matter (TSP) in the ambient air in an urban area in Ho Chi Minh City, Vietnam and in Osaka, Japan was carried out from 2005 to 2006. The objective of this study was to investigate the environmental levels, emission sources, seasonal variations and health risk of eleven PAHs in the two cities, especially Ho Chi Minh City where air pollution is becoming a serious concern. The results showed that the concentrations of TSP and total PAHs were significantly higher in Ho Chi Minh City than levels in Osaka. The concentrations of 5- and 6-ring PAHs (BeP, BbF, BkF, BaP, BghiP and InP) were much higher in TSP samples in Ho Chi Minh City than in Osaka, accounting for 82% and 51% of total PAHs, respectively. These PAHs are known to be highly carcinogenic and mutagenic in humans. Vehicular emission is suggested as one of the main pollution sources of PAHs in both cities. Motorcycles and gasoline automobiles are suggested as the main emission sources of PAHs in Ho Chi Minh City, whereas diesel automobiles are the primary source in Osaka. Seasonal variations of PAHs were observed in this study; higher concentrations of PAHs were found in the rainy season (May-December) and lower concentrations corresponded to the dry season (February-April) in Ho Chi Minh City, while higher concentrations of PAHs were observed in the winter (November-January) in Osaka. The number of sunshine hours was an important meteorological factor affecting seasonal variations of PAHs in Ho Chi Minh City, while the temperature was a main factor causing the variations of PAHs in Osaka. The high BaP equivalent concentration of 5- and 6-ring PAHs even in the ambient air is an alarming signal for harmfulness to human health and environmental quality in Ho Chi Minh City.     

Differential Retinal Protein Expression in Primary and Secondary Retinal Ganglion Cell Degeneration Identified by Integrated SWATH and Target-Based Proteomics

To investigate the retinal proteins associated with primary and secondary retinal ganglion cell (RGC) degeneration and explore their molecular pathways, SWATH label-free and target-based mass spectrometry was employed to identify the proteomes in various retinal locations in response to localized optic nerve injury. Unilateral partial optic nerve transection (pONT) was performed on adult Wistar rats and their retinas were harvested 2 weeks later. To confirm the separation of primary and secondary RGC degeneration, immunohistochemistry of RNA binding protein with multiple splicing (RBPMS) and glial fibrillary acidic protein (GFAP) was performed on retinal whole-mounts. Retinal proteomes in the temporal and nasal quadrants were evaluated with high resolution hybrid quadrupole time-of-flight mass spectrometry (QTOF-MS), and SWATH-based acquisition, and their expression was compared to the corresponding retinal quadrant in contralateral control eyes and further validated by multiple reaction monitoring mass spectrometry (MRM-MS). A total of 3641 proteins (FDR < 1%) were identified using QTOF-MS. The raw data are available via ProteomeXchange with the identifier PXD026783. Bioinformatics data analysis showed that there were 37 upregulated and 25 downregulated proteins in the temporal quadrant, whereas 20 and five proteins were upregulated and downregulated, respectively, in the nasal quadrant, respectively (n = 4, p < 0.05; fold change ≥ 1.4-fold or ≤0.7). Six proteins were regulated in both the temporal and the nasal quadrants, including CLU, GFAP, GNG5, IRF2BPL, L1CAM, and CPLX1. Linear regression analysis indicated a strong association between the data obtained by means of SWATH-MS and MRM-MS (temporal, R² = 0.97; nasal, R² = 0.96). Gene ontology analysis revealed statistically significant changes in the biological processes and cellular components of primary RGC degeneration. The majority of the significant changes in structural, signaling, and cell death proteins were associated with the loss of RGCs in the area of primary RGC degeneration. The combined use of SWATH-MS and MRM-MS methods detects and quantifies regional changes of retinal protein expressions after localized injury. Future investigation with this integrated approach will significantly increase the understanding of diverse processes of progressive RGC degeneration from a proteomic prospective.     

Nanophase Decomposition of a Zn-Al Based Alloy Zn68Al10Cu22

The nanostructural evolution and phase transformation of the films of a Zn-Al based alloy (Zn68Al10Cu22 in wt pct)have been studied by using X-ray diffraction and scanning electron microscopy. Nanostructural thin films of the Zn-Al based alloy were produced by using an electron beam deposition technique. It was found that a nanocrystalline phase η'n had a strong preferred crystal orientation at (0002) crystal planes in the as-deposited films. During ageing at 220℃, the decomposition of nanophase η'n started with clustering to form Z-zones, and transitional phase, which was accompanied by an eutectoid decomposition of the η'n phase: η'n→β'eut T'. Decomposition, such as clustering and the formation of the Z-zones, and the transitional phase etc. were observed in the nanophaseβ'eut. The formation and the decomposition of the transitional phase of micrometers in size were involved in the decomposition of the main nanophase η'n. The mechanism of the Z-zones formation and the stability of nanophases were discussed.     

Emission wavelength dependence of fluorescence lifetimes of bacteriological spores and pollens

Concern about biological terrorism has greatly increased in the 21st century, and correspondingly, so has the need for accurate detection and identification of biological hazards, such as Bacillus anthracis. Optical techniques have been shown to be useful for this purpose. Use of fluorescence lifetimes as a function of emission wavelength for different materials using point- detection methods appears to be an additional viable option. Although the lifetimes range only between 2 and 6 ns, most biological materials tested in this study were distinguishable. A preliminary database has been compiled for use in a possible future detection system.     

Biodiesel production using enzymatic transesterification - Current state and perspectives

Biodiesel has attracted considerable interest in recent years as an alternative, biodegradable and nonpolluting transportation fuel. Conventional alkaline process for biodiesel production are energy-consuming and generate undesirable by-products such as soaps, that make difficult the separation and purification of biodiesel.Particular attention has been dedicated to the use of lipases as biocatalysts for biodiesel production due to their favorable conversion rate obtained in gentle conditions and relatively simple downstream processing steps for the purification of biodiesel and by-products. However, comparatively to conventional chemical processes, the major obstacles for enzymatic production of biodiesel remain the cost of lipases, the relatively slower reaction rate and lipases inactivation caused by methanol and glycerol.This review evaluates the current status and perspectives for enzymatic biodiesel production and indicates the key operational variables that influence lipase activity and stability together with the technological solutions for industrial implementation of enzymatic process.     

Mechanical Characterization and Water Ageing Behavior Studies of Grewia Serrulata Bast Fiber Reinforced Thermoset Composites

Natural fiber-reinforced polyester composites were prepared using bast fibers as the reinforcement which were extracted from Grewia serrulata trees. Chemical treatments such as alkali pretreatment followed by permanganate treatment, acetylation and silane treatment were exclusively applied to modify the fiber surface. Hand lay-up technique with compression molding was adapted for the fabrication of axially oriented fiber reinforced composites. Tensile, flexural and impact strength properties of the specimens prepared were evaluated following the standard procedures. The SEM images of the fractured surfaces shows improvement in compatibility between the chemically treated fibers and the matrix. It was found that the tensile and flexural strengths of chemically treated fiber-reinforced polyester composites have significantly improved when compared to untreated fiber-reinforced polyester specimens. The properties of 1200 hrs water aged specimens were found deteriorated considerably due to diffusion of water into the composite material system. The chemical treatment of fibers prior to fabrication of composites improves the resistance to water absorption tendencies.