Sintering of Industrial Mullites in the Presence of Magnesia as a Sintering Aid

The sinterability of two industrial mullite powders, in the presence of MgO as a sintering aid, was investigated. A glassy phase, which was generated during preparation, was present in both powders; this glassy phase had a strong influence on sintering, depending on its content, composition, and spatial distribution. MgO promoted sintering in the presence of a liquid phase, both in the as-received materials and in samples washed with HF, in which most of the pre-existing glassy phase was eliminated. Investigations using transmission electron microscopy, coupled with energy-dispersive spectroscopy, as well as dilatometric measurements and X-ray diffraction data, on washed and unwashed materials and on quenched and slow-cooled samples allowed a better understanding of the influence of MgO and the glassy phase on the sintering behavior and the formation of new phases. Most of the phases, in fact, can be explained by using the MgO–Al₂O₃–SiO₂ phase diagram, even in such complex systems.     

Cytostatic activity of 1,10-phenanthroline derivatives generated by the clip-phen strategy

The cytostatic activities of a series of twelve 1,10-phenanthroline (Phen) derivatives and of their copper complexes were studied on L1210 murine leukemia cells. Large increases in the biological activity were observed for compounds of the 3-Clip-Phen series, in which two Phen moieties were bridged at their C3 positions by an alkoxy linker, the 3-pentyl-Clip-Phen derivative showing an IC(50) value of 130 nM while Phen shows an IC(50) value of 2500 nM under the same conditions. IC(50) values seemed to be modulated not only by the position, the nature, and the length of the linker of Clip-Phen but also by hydrophobicity. Since copper complexes of Phen are chemical nucleases and nucleic acids are thus a potential target for these compounds, the corresponding copper complexes were also studied. Copper complexation of the 3-Clip-Phen ligands did not increase their biological activities. Attempts to vectorize 3-Clip-Phen derivatives with a DNA binder such as spermine or with a cell-penetration peptide failed to increase their biological activity relative to the original 3-Clip-Phen series.     

Thermal Ageing Induced Effects on Pd/LaFeO3 for NOx Reduction by Hydrocarbons: Influence of the Preparation Method

The influence of the support synthesis for the preparation of supported Pd/LaFeO₃ perovskite based catalysts and the nature of the palladium precursor on the catalytic performances in the selective reduction of NO to N₂ by hydrocarbons have been investigated. According to the preparation method, subsequent surface and bulk characterisation revealed significant changes in the degree of dispersion and the chemical environment of oxidic palladium species depending on the extent of interaction with the support. Pd nitrate precursor leads to the stabilisation of the Pd surface concentration. The metal support interactions thus obtained strongly enhance the catalytic performances, particularly the resistance to thermal ageing whereas sol–gel synthesis produces the higher support activity.     

Interface step-induced thin-film delamination and buckling

Atomistic simulations based on experimental observations provide the first evidence that the interface delamination of a thin film from its substrate may start from interface steps. Buckling of the film after interface gliding from both edges of its delaminated part is also observed. In the framework of the Föppl–von Kármán theory of thin plates, the expression of the critical strain beyond which the film buckles has been then analytically determined as a function of the step height and gliding displacements. Both numerical and analytical results confirm that the formation of blisters is favoured in the neighbourhood of interfacial imperfections.     

In vitro kinetic analysis of carbohydrate and aromatic amino acid metabolism of different members of the human colon

The carbohydrate and aromatic amino acid metabolism of several species related to the human colon was investigated into more detail. Therefore, in vitro fermentations were performed, with different carbohydrate sources, during which several aromatic amino acids were added to the fermentation medium. Shifts in end-product formation in response to the available nutrients were observed for all strains tested. The major part of amino acid degradation occurred after depletion of the carbohydrates. Moreover, it was shown that Bifidobacterium strains are capable of degrading aromatic amino acids in the absence of carbohydrates. The excretion of certain intermediates of the aromatic amino acid metabolism was observed for a strain of Clostridium clostridioforme, after which they were metabolized again during a later stage of fermentation. This implies that cross-feeding on degradation products of aromatic amino acids, albeit within the same species, can occur in the human colon.     

Retail competition in electricity markets

The introduction of competition into retail electricity supply gave rise to great expectations. However, to date, its performance has proven less than stellar, owing primarily to the theoretical concepts underpinning this reform, which draw heavily on the Austrian school. Neither consumers’ decision processes nor this sector's technical paradigm were adequately accounted for, leading to an uncorrect estimation of the expected impact of opening to competition. Short- and medium-term prospects for the evolution of retail markets must be reconsidered from the perspective of greater stability: not a generalization of competition, but rather a persistent segmentation between active and inactive clients; not a large and rapid diffusion of radical innovations in commercialisation, with the potential for undermining the incumbents’ positions.     

Time course of peptide fingerprints in semimembranosus and biceps femoris muscles during Bayonne ham processing

The aim of this work was to define reliable markers of muscle and processing time in dry-cured ham using a rapid, precise semi quantitative method for the protein fraction soluble in low ionic strength buffer. For this purpose protein labchip Agilent was used to separate proteins and peptides and accurately determine their molecular weights and concentrations electrophoretically. In this way the protein fingerprinting of dry-cured ham at different process times was characterised, together with targets and products of proteolysis. In addition, the comparison of all the electrophoregrams indicated muscle and dry-curing process markers.     

开关电源环路中的TL431

在此前一系列的3篇文章中,指出了如何采用TL431来实现1类和2类补偿器。如果前述补偿器类型适合大多数电流模式控制配置工作,其它控制模式则可能需要3类补偿器。举例来说,如果需要对连续导电模式（CCM）电压模式转换器进行补偿,就需要额外的极点和零点。在这3类配置中,TL431并不太有利于实践这样的设计：眼前的快通道（fast lane）显然会使设计工作复杂化。本文提出了简单的构想,以与所观测到交流输入完全解耦的外部直流偏置来消除快通道。这样一来,设计工作被简化,类似于采用运放来构建传统的3类补偿器。     

Dielectric and viscoelastic studies of curing epoxy-amine model systems

Summary The curing of different epoxy-amine model systems which present only gelification and/or vitrification processes has been followed with the evolution of their viscoelastic and electrical behaviours during the network formation. Some attempts are performed to correlate the significant evolution of the mechanical and electrical parameters with the physico-chemical changes of these well defined chemical systems during their hardening and complete curing.     

Influence of hysteresis on the transient hygrothermal response of a hemp concrete wall

Building envelopes with bio-materials like hemp concrete are currently undergoing an increasing development due to their low environmental impact and their interesting hygrothermal properties. This kind of hygroscopic material is characterized by a hysteretic behaviour. In this paper, the influence of such behaviour on the hygrothermal response of a building wall is discussed. An experimental facility is designed to measure temperature and relative humidity within a hemp concrete wall submitted to climatic variations. This facility provides a set of experimental data suited for benchmarking. Numerical simulations are performed with a hysteresis model implemented in a heat and moisture transfer model. Comparisons between numerical and experimental results show that hysteresis modelling is relevant to simulate the hygrothermal response of the wall. The discussion is extended to the influence of the initial moisture content.