Durability of fire retardant treated wood products at humid and exterior conditions review of literature

Fire retardants may considerably improve the fire properties of wood products, but the durability, e.g. in exterior applications, has not been addressed fully. This paper reviews the existing knowledge and experience mainly from the USA with the aim of supporting further development in Europe. The review is concentrated on pressure impregnated fire retardant treated wood products which have the best opportunities for increased durability. Copyright © 2001 by John Wiley & Sons, Ltd.     

电池管理应用中精确测量和温度稳定的重要性

锂离子电池由于拥有能量密度高、电压高、自放电率低,以及无记忆效应等优势,因而逐渐成为使用充电电池的便携应用产品的常用技术。     

Pyrolytic formation of polycyclic aromatic hydrocarbons from sesquiterpenes

The products of the pyrolysis of four sesquiterpenes, β-caryophyllene, α-cedrene, longifolene and valencene, have been examined. Pyrolysis was carried out at 300, 400 and 500°C, the products determined by GC-MS and then examined for similarities and differences using multivariate data analysis. Analysis showed that longifolene was most resistant and caryophyllene least resistant to pyrolysis with cedrene and valencene occupying intermediate positions. While the compounds were largely unchanged at 300°C, polycyclic aromatic hydrocarbons (PAHs) were major components of the pyrolysates at 400 and 500°C. No less than nine of the 16 EPA priority pollutants were present in the pyrolysates at the higher temperatures.     

Growth and characterization of (Pb,La)(Zr,Ti)O3 thin film epilayers on SrTiO3-buffered Si(001)

Ferroelectric Pb_0.92La_0.08Zr_0.4Ti_0.6O₃ (PLZT) thin films were deposited on SrTiO₃-buffered Si(001) substrate by on-axis radio frequency magnetron sputtering. X-ray diffraction analysis revealed epitaxial growth of monocrystalline PLZT films, with an (001) rocking curve full width at half maximum of ∼ 0.3°. φ-scans showed 45° in-plane orientation of the perovskite unit cell relative to that of silicon. The elemental composition of the thin film heterostructure was examined by Auger sputter depth profiling measurements. The recorded profiles suggest that the SrTiO₃ buffer layer serves not only as a template for epitaxial growth, but also as a barrier suppressing Pb-Si interdiffusion between the PLZT layer and the Si substrate. The surface roughness of the PLZT layer was measured at ∼ 4 nm for films with ∼ 500 nm thickness. Wavelength dispersions for the refractive index (n) and the extinction coefficient (k) were obtained from spectroscopic ellipsometry measurements, with n ∼ 2.48 at the main communication wavelength λ = 1550 nm and k < 0.001 for λ > 650 nm. Recorded polarization vs. electric field loops for the PLZT epilayer, with a SrRuO₃ electrode layer interposed between PLZT and SrTiO₃, showed a remnant polarization P_r ≈ 40 µC/cm² and coercive field E_c ≈ 100 kV/cm. These findings suggest that the sputter-deposited PLZT thin films retain the functional properties critical to ferroelectric and electro-optic device applications, also when integrated on a semiconductor substrate.     

Crossover from spin-flop coupling to collinear spin alignment in antiferromagnetic/ferromagnetic nanostructures

The technologically important exchange coupling in antiferromagnetic/ferromagnetic bilayers is investigated for embedded nanostructures defined in a LaFeO(3)/La(0.7)Sr(0.3)MnO(3) bilayer. Exploiting the element specificity of soft X-ray spectromicroscopy, we selectively probe the magnetic order in the two layers. A transition from perpendicular to parallel spin alignment is observed for these nanostructures, dependent on size and crystalline orientation. The results show that shape-induced anisotropy in the antiferromagnet can override the interface exchange coupling in spin-flop coupled nanostructures.     

对加劲板在局部和整体弯曲作用下的后屈曲及强度的半解析分析

对经受平面内双轴及剪切荷载作用下的带缺陷加劲板的预先和后屈曲分析采用半解析方法分析。结合了Rayleigh-Ritz方法的大变形理论,可以分析板局部及整体的平衡。采用vonMises屈服标准预测的极限强度作为膜压力的破坏标准。采用Fortran程序计算的结果也被非线性有限元分析的结果证实。该法因此也适用于结构优化设计以及可靠性研究。     

Improving Thermal Stability in Cu-Containing Al-Mg-Si Alloys by Precipitate Optimization

It is demonstrated that good thermal stability in Al-Mg-Si-Cu aluminum alloys correlates with a high density of fine lath-shaped, Cu-containing, disordered L-precipitates. Alloys optimized for L retained hardness above 90 HV after 3 weeks over-aging at 473 K (200 °C). Further improvement was achieved by substituting Si by Ge in one alloy. High-angle annular dark-field scanning transmission electron microscopy showed that at peak-hardness conditions, L coexists with more common needle-shaped precipitates, often with Cu-enriched interfaces.     

The effect of uncertainty and aggregate investments on crude oil price dynamics

This paper is a study of the dynamics of the oil industry and we derive a mean reverting process for the crude oil price. Oil is supplied by a market leader, OPEC, and by an aggregate that represents non-OPEC producers. The non-OPEC producers take the oil price as given. The cost of non-OPEC producers depends on past investments. Shifts in these investments are influenced by costs of structural change in the construction industry. A drop in the oil price to below a given level triggers lower investments, but if the oil price reverts back to a high level investments may not immediately expand. In an uncertain oil demand environment cost of structural change creates a value of waiting to invest. This investment behaviour influences the oil price process.