E.p.r. studies on poly(paraphenylene)s synthesized by two different routes

Polyphenylene has been prepared using two different polymerization procedures. We show that, if the two materials are very similar from a structural point of view, their magnetic properties as seen by e.p.r. are very different. We show that the existence of unpaired spins in one of these polymers is correlated with structural defects which are probably created during the polymerization process.     

Thermal and mechanical properties of tetramethyl-p-silphenylenesiloxanedimethylsiloxane block copolymer

Several kinds of $\text{tetramethyl}\text{-p-}\text{silphenylenesiloxane}\text{dimethylsiloxane}$ (TMPS/DMS) block copolymers having various compositions and segment lengths were synthesized by the polycondensation of p-bis(dimethylhydroxysilyl)benzene and silanol-terminated DMS oligomers of different degrees of polymerization, which were 19, 43, 300, 380 and 540 DMS monomer units. The compositions ranged from TMPS/DMS wt% ratio of 100/0 to 24/76. For these copolymers, differential scanning calorimetry was carried out to determine the melting temperatures, the heat of fusion and the crystallinities. The melting temperatures and the crystallinities of the block copolymers were found to decrease as DMS contents were increased from 11 to 76 wt% and as DMS segment lengths were decreased from 540 to 19. The crystalline parts of TMPS segment would be increased according to the long TMPS sequences which were obtained from the copolymerizations by using DMS oligomers with high degrees of polymerization such as 300, 380 and 540. The stress-strain behaviour and the dynamic mechanical behaviour were also investigated for these copolymers. The tensile strength was decreased and the percentage elongation was increased with increasing DMS content and segment length. In the case of the copolymers for which the DMS contents remained constant at 26 wt%, two major transitions were observed at around ?120° and ?10°C for the copolymers having DMS block sizes of 300, 380 and 540. But for the copolymers having those of 19 and 43 the two transitions merged together at ?50°C. The relaxations at ?120°C corresponding to the glass transition of DMS component and those at ?10°C are due to the amorphous TMPS phase which is separated from the DMS phase owing to the longer sequence length. The relaxation observed around ?50°C is due to the shorter sequence length of TMPS in the main chain plus the presence of more flexible DMS component. It may be suggested that the long sequence length causes large domains of hard and soft phases which consist of TMPS and DMS blocks respectively.     

Does tailoring help people find the information they need?

In this paper, we present an empirical study assessing the impact of tailoring on information-seeking tasks. Our aim was to evaluate whether providing tailored information would help people find the information they need more quickly and accurately. Our results show that tailored documents have an impact on information-seeking, at least when the information to be found is spread over a number of sources and needs to be synthesised. With documents tailored to their needs, people can find the information they seek more quickly, and overall, more accurately. In our study, we also investigated how people looked for information to gain a better understanding of the strategies employed by people to find information.     

Modelling load-settlement behaviour of piles using high-order neural network (HON-PILE model)

An accurate estimation of pile response to loading is a challenging task due to the complexity of the soil-pile interactions and uncertainties in the soil properties. Conventional methods of predicting pile load-settlement relationship either oversimplify the problem or require the parameters that are difficult to determine in the laboratory. In this study, a high-order neural network (HON) is developed to simulate the pile load-settlement curve using properties of the pile and SPT data along the depth of pile embedment as inputs. The results indicated a significant improvement in the quality of HON predictions over that of BPN, RBF and GRNN models. Based on the comparisons with the predictions of elastic and hyperbolic models, the proposed HON model provides better predictions than existing theoretical models.     

Computer modelling of wire strands and ropes part II: Finite element-based applications

In the comparison with the theoretical analyses of wire strands reported in the literature where obviously single-layered strands with a construction of the 1 + 6 wires were modelled and analysed, this paper is focused on a multi-layered strand with a construction of the 1 + 6 + 12 + 18 wires. The geometric parametric equations developed in the first part of this paper [1] are implemented in CATIA V5 software code for geometric modelling of the multi-layered strand. The methodology of their implementation and the approach for the generation of the strand geometric model are demonstrated. To predict the behaviour of the multi-layered strand under tensile loads, the mathematical geometric model is further implemented in a finite element program. For this purpose ABAQUS/Explicit software is used. The derived 3D geometric models of the multi-layered strands and the results of the finite element elastic behaviour analyses of the strand under tension loads are validated through comparisons with experimental and theoretical data available. The results obtained confirm the correctness of the derived parametric equations and mathematical and physical importance of the finite element model developed.     

压缩非石棉密封材料机械性能的试验研究

对所研制的几种压缩非石棉（CFS）密封板的机械性能进行了试验研究，比较了压缩非石棉板与传统石棉橡胶板（CAF）和进口CFS的差异，分析了代石棉纤维含量对石棉板性能的影响，阐述了适宜的纤维及其含量有利于提高板材的综合性能。     

Synthesis,Structure and Tribological Properties of Stearic Acid Coated (NH4)3PMo12O40 Nanoparticles

A new kind of oil additive, stearic-acid-coated (NH₄)₃PMo₁₂O₄₀ nanoparticles was synthesized by a chemical method. The morphology and structure was characterized by means of transmission electron microscopy; X-ray powder diffraction and Fourier transform infrared spectroscopy. The tribological properties of coated (NH₄)₃PMo₁₂O₄₀ nanoparticles as oil additives in liquid paraffin were evaluated in a four-ball machine. The results showed that the coated (NH₄)₃PMo₁₂O₄₀ nanoparticles have an average diameter of about 20 nm, and the (NH₄)₃PMo₁₂O₄₀ nanocore has a Keggin structure. As oil additives they dramatically improved the antiwear ability of liquid paraffin, and enhanced the friction-reduction and load-carrying ability of liquid paraffin to some extent. The rubbed surface was investigated by scanning electron microscopy and X-ray photoelectron spectrometry. It was found that the boundary film on the worn surface was composed of MoO₃, (NH₄)₂MoO₇ and Fe₂O₃. Which contributed to the good tribological properties of the oil.     

Antiwear Properties of Phosphorous-Containing Compounds in Vegetable Oils

Antiwear properties of vegetable oils were investigated under boundary lubrication conditions using the four-ball wear test (ADTM D 4172). Additive-free vegetable oils exhibit similar antiwear properties, which are superior to those of additive-free mineral oils. Phosphorus-containing compounds such as zinc bis(dialkyldithiophosphate) and dialkyl phosphonates improve the antiwear properties of vegetable oils. The effect of the additives on wear reduction was found to depend on the peroxide value of the base oil. It is considered that peroxides decompose the antiwear additives to less active forms. The formation of peroxides by the autooxidation of vegetable oils was observed even at room temperature. Sunflower oil exhibits good oxidation stability, which may promise success in various applications.     

软弱围岩复合式隧道衬砌模型试验研究

试验研究了软弱围岩直墙式和曲墙式隧道衬砌的变形、承载能力和破坏特征，发现曲墙式复合衬砌受力特性明显优于直墙式，为今后合理地设计该种衬砌结构提供了可靠的试验依据。     

Animal welfare in organic farming systems

The concept of farm animal welfare can, for practical purposes, be translated into the so‐called Five Freedoms. 1 Organic farming aims to meet animal welfare needs and should therefore comply with these Freedoms. The first Freedom, from hunger and thirst, is met in any system properly managed to organic standards. The Freedom from thermal and physical discomfort is challenged as organic husbandry systems face more climatic extremes. However, they also provide more ‘control’ to the animal by offering a choice when seeking warmth or a cool place to lie. The Freedom from pain, injury and disease is the most complicated one. Organic farming virtually bans mutilations (e.g. debeaking, tail docking), although some are still allowed and practised (e.g. castration). Organic animals are more exposed to wildlife and at risk of contracting infectious diseases. However, it is possible (although not proven) that organically managed animals are more resistant to illness. The Freedom to express normal behaviour is met through environmental enrichment and group housing. The Freedom from fear and distress is supported by e.g. extra (social) space. In conclusion, if animal health can be maintained, organic farming is very well placed to provide good animal welfare. Copyright © 2007 Society of Chemical Industry