Compression mechanical properties of wood at temperatures simulating fire conditions

Compression mechanical properties of wood at temperatures simulating fire conditions have been obtained for use in structural response models to aid the design of light-timber framed walls as fire barriers in accordance with recent performance-based fire codes. The properties that have been measured are elastic modulus and strength. The properties were obtained from samples that had a number of similarities to studs in walls. The effects of knots, however, have been excluded from this study. The elastic modulus greatly reduces as temperatures approach the vaporization point of moisture. The properties were significantly lower compared with properties given in the literature. Input of the measured properties into a structural fire model for walls led to good comparisons with results of experiments on walls with low load ratios (that is, the ratio of the applied load to the collapse load capacity at ambient conditions). Such walls are typically used in building construction. However, the elastic moduli presented in this paper and in other literature do not lead to good model predictions for slender walls with high load ratios. Further research into creep is required. Copyright © 2001 John Wiley & Sons, Ltd.     

Improvement of single-walled carbon nanotube transparent conductive films using substrate pretreatment

This study sought to improve the characteristics of single-walled carbon nanotube (SWCNT) transparent conductive films (TCFs), such as their sheet resistance and transparency, by applying pre-treatments to their PET substrates. Oxygen–argon plasma pretreatment was found to increase the surface energies of the PET substrates from 33.9 to 74.2 mJ/m², which improves the electric conductivity of the SWCNT-TCFs and provides a lower sheet resistance at a given light transmittance. Polymer electrolyte solution pretreatment was used to vary the surface functionality and modulate the surface charges quantitatively, as confirmed by the measurement of the resulting substrate zeta potentials, which varied between ?45.8 and 18.2 mV. When the surfaces became negatively charged through pretreatment, the electric conductivities of the SWCNT-TCFs were increased. Both pre-treatments also improve the adsorption of SWCNTs onto the PET substrates and reduce the loss of coating solution during the spray deposition of SWCNTs.     

Performance evaluation of a high durability asphalt binder and a high durability asphalt mixture for bridge deck pavements

This paper describes the results of laboratory and full-scale performance tests for a high durability asphalt binder (HDAB) and high durability asphalt mixture (HDAM) applicable to the wearing course in a bridge deck system. The HDAB was developed using a styrene–butadiene–styrene (SBS) modifier and hydrocarbon for improving construction workability and resistance to fatigue cracking. Various binder tests were conducted on the HDAB, and test results showed that the resistance to fatigue and low temperature cracking of the HDAB increased significantly compared to that of the PG 64-22 and PG 76-22 binders. For the mixtures, the fatigue test results showed that the HDAM has a three times longer fatigue life than the SBS-modified asphalt mixture. It was also found that the HDAM has a higher resistance against moisture-induced damage. Results from full-scale accelerated testing on the bridge deck pavement system proved that the HDAM can significantly improve pavement performance.     

澳门1999-2009——回归后第一个十年之建筑与城市

本期专辑描绘了澳门从1999年-2009年主权从葡萄牙管辖下回归祖国之后10年间的建筑与城市化进程。在这期间,澳门作为一个特别行政区经历了非凡的10年,在这10年间,澳门的发展是意义深远的,这次的主题也同样跟随澳门的发展方向转变,是从1990年代的＂文化之城＂到＂亚洲的拉斯维加斯＂和将来有可能的＂知识之城＂这样的顺序展开的。     

Formation and structural characterization of potassium titanates and the potassium ion exchange property

In the present work, K₂Ti₂O₅, K₂Ti₄O₉ and K₂Ti₆O₁₃ are synthesized by solid state method. Their structures and morphologies are characterized by X-ray diffraction, Raman spectra and scanning electron microscopy. The binding energies of K, Ti and O in potassium titanates were then evaluated by X-ray photoelectron spectroscopy and compared with those in K/TiO₂. Finally the corresponding K ion exchange properties are investigated by synthesizing NO oxidation catalysts with Co(NO₃)₂ precursor. It is found that the binding energy of K in K₂Ti₂O₅ is much higher than those in K₂Ti₄O₉and K₂Ti₆O₁₃, and because of which, it shows quite different catalytic performances. Compared with other potassium titanates, the K in K₂Ti₂O₅ is much easier to be exchanged out.     

Quantum‐dots‐based detection of hepatitis C virus (HCV) NS3 using RNA aptamer on chip

BACKGROUND: Over 170 million people, more than 3% of the world's population, suffer from the hepatitis C virus (HCV) infection and the rate of death from liver‐related mortality to HCV has increased. In respect of this, the development of assays for biological imaging should be urgently considered as an essential factor in diagnosis. RESULTS: A novel HCV‐detecting technique using a nanoparticle‐supported aptamer probe was demonstrated. With the aid of nanoparticle quantum dots (QDs) with carboxyl group as an imaging probe, and 5′‐end‐amine‐modified RNA oligonucleotide as a capturing probe, target HCV NS3 was visually detected on chip. The QDs‐based RNA aptamer for HCV NS3 showed high selectivity and specificity against other protein such as BSA. The detection limit of HCV NS3 protein was 5 ng mL^?1 level. CONCLUSION: With a novel strategy for protein–aptamer interaction, the feasibility of applying QDs‐based fluorescent detection technique to HCV viral protein assay for the development of a protein biochip was demonstrated. This scheme of QDs‐mediated imaging with a target‐oriented specific RNA aptamer for the detection of infectious HCV diseases provides an efficient strategy and a promising new platform for monitoring applications. Copyright © 2010 Society of Chemical Industry     

Induction of Phenolic Glycosides by Quaking Aspen (<Emphasis Type="Italic">Populus tremuloides)</Emphasis> Leaves in Relation to Extrafloral Nectaries and Epidermal Leaf Mining

We studied the effect of epidermal leaf mining on the leaf chemistry of quaking aspen, Populus tremuloides, during an outbreak of the aspen leaf miner, Phyllocnistis populiella, in the boreal forest of interior Alaska. Phyllocnistis populiella feeds on the epidermal cells of P. tremuloides leaves. Eleven days after the onset of leaf mining, concentrations of the phenolic glycosides tremulacin and salicortin were significantly higher in aspen leaves that had received natural levels of leaf mining than in leaves sprayed with insecticide to reduce mining damage. In a second experiment, we examined the time course of induction in more detail. The levels of foliar phenolic glycosides in naturally mined ramets increased relative to the levels in insecticide-treated ramets on the ninth day following the onset of leaf mining. Induction occurred while some leaf miner larvae were still feeding and when leaves had sustained mining over 5% of the leaf surface. Leaves with extrafloral nectaries (EFNs) had significantly higher constitutive and induced levels of phenolic glycosides than leaves lacking EFNs, but there was no difference in the ability of leaves with and without EFNs to induce phenolic glycosides in response to mining. Previous work showed that the extent of leaf mining damage was negatively related to the total foliar phenolic glycoside concentration, suggesting that phenolic glycosides deter or reduce mining damage. The results presented here demonstrate that induction of phenolic glycosides can be triggered by relatively small amounts of mining damage confined to the epidermal tissue, and that these changes in leaf chemistry occur while a subset of leaf miners are still feeding within the leaf.     

Antiobese and hypocholesterolaemic effects of an Adenophora triphylla extract in HepG2 cells and high fat diet-induced obese mice

The ethyl acetate extract from Adenophora triphylla root (ATea) had strong antioxidant effect. We hypothesised that a high fat (HF) diet might induce oxidative stress and so, dietary antioxidant may have beneficial effects on hypercholesterolaemia, but the underlying mechanisms involved are not fully understood. To test this hypothesis, C57BL/6 mice were fed with HF diet for 9 weeks. In the last 4 weeks, the HF diet was supplemented with 0, 25 or 75 mg/kg ATea. ATea decreased body weight gain and both ATea doses significantly reduced the plasma and hepatic cholesterol levels of the obese mice. Analysis of the hepatic expression of proteins known to play important roles in cholesterol metabolism indicated that ATea significantly enhanced low density lipoprotein receptor (LDL receptor) and cholesterol 7α-hydroxylase (CYP7A1) expression but inhibited the 3-hydroxy-3-methylglutaryl–CoA reductase (HMG–CoA reductase) expression in HepG2 cells and mice. No mutagenic activity was observed at high doses of ATea.     

Hydrogen adsorption on Li metal in boron-substituted graphene: An ab initio approach

The characteristics of hydrogen adsorption on Li metal atoms dispersed on graphene with boron substitution is investigated including Li clustering, hydrogen bonding characteristics, and the open metal states of Li adatom using density functional theory calculations. It is found that Li atoms are well dispersed on boron-substituted graphene and can form the (2 × 2) pattern because clustering of Li atoms is hindered by the repulsive Coulomb interaction between Li atoms. One Li adatom dispersed on the double side of graphene can absorb up to 8 hydrogen molecules corresponding to a 13.2% hydrogen storage capacity. In addition, the adsorption behaviors of non-hydrogen atoms such as C and B are calculated to determine whether Li atoms can remain as the open metal state in boron-substituted graphene.     

Magnetic-separable robust microbeads using a branched polymer for stable enzyme immobilization

Uniform magnetic separable robust microbeads using a branched polymer were successfully developed for stable enzyme immobilization. The changed morphology of the microbeads was shown by scanning electron microscopy (SEM) analysis. The aldehyde groups on the polymers and imine groups derived from the Schiff base reaction between the aldehyde and amine moiety were found as the evidence of these reactions based on Fourier transform infrared (FT-IR) spectroscopy. The amine groups of the enzyme react with the aldehyde groups on the glutaraldehyde polymer so that the stable conjugations are formed. The specific activity of the conjugated enzyme was found to be retained more than 50%, but the reaction rate constant, K_m value was not changed, compared to the free enzyme. In addition, the enzyme conjugated in the microbeads was found to be highly stable for more than 50 days, pertaining over 60% of its initial activity, even after being reused more than 15 times repeatedly. Furthermore, the magnetic-driven controllability provided facile separable characters for the repeated recycling. It is expected that these microbeads can be utilized as a key tool for successful realization not only in enzymatic conversion processes but also in extended fields; bio-based sensors or analytical devices, bioprocessing, bioremediation, to name only a few of numerous areas.