Synthesis of new soluble polybenzyls by Friedel–Crafts reactions

Soluble polybenzyls were prepared by a catalytic electrophilic Friedel–Crafts type polycondensation between α,α′-dichloro-p-xylene and substituted (by an alkyl or an alkoxy side-chain) mesitylene. The influence of the length of the side-chain on the solubility of the polymer was examined. The polymers were found to be soluble in common organic solvents. Polymer characterizations were made by ¹³C nuclear magnetic resonance spectroscopy (NMR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and elemental analysis. © 1999 Society of Chemical Industry     

Further Exploration of Controlled and Automatic Memory Processes in Early Alzheimer's Disease.

The authors' aim in this study was to explore automatic and controlled processes in Alzheimer's disease (AD) by using a variant of the word-stem completion task that applies the process-dissociation procedure. Several methodological precautions were taken in order to limit problems observed in previous studies (e.g., poor task sensitivity, ceiling and/or floor effects, no control over comprehension of instructions). Our results (a) confirmed the marked deterioration in controlled processes and (b) showed that when psychometric constraints were limited, automatic memory processes were preserved in AD. These data are in line with those from more global studies in suggesting that AD is characterized by an early deterioration in controlled processes and an initial preservation of automatic processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modelling of multiple-mechanism agglomeration in a crystallization process

A three-level agglomeration model coupled with crystal growth is developed. It accounts for Brownian, laminar, and turbulent agglomeration. The desupersaturation profiles, the particle size distributions, the average sizes, and variances (or standard deviations), as well as the instantaneous agglomeration degrees for each mechanism, can be calculated as functions of time. The model is applied to the crystallization of an amorphous solid into a crystalline polymorph in a batch crystallizer. A runaway phenomenon is detected for agglomeration when crystals are switching over from the Brownian regime to the laminar one: this switchover significantly affects the desupersaturation curve and the crystal shapes.     

Self-propagating combustion synthesis of intermetallic matrix composites in the ISS

Combustion Synthesis experiments have been performed on the ISS (International Space Station) during the Belgian taxi-flight mission ODISSEA in November 2002, in the framework of the ESA-coordinated project COSMIC (Combustion Synthesis under Microgravity Conditions). The main objective of the experiments was to investigate the general physico-chemical mechanisms of combustion synthesis processes and the formation of products microstructure. Within the combustion zone, a number of gravity-dependent phenomena occur, while other phenomena are masked by gravity. Under certain conditions, gravity-dependent secondary processes may also occur in the heat-affected zone after combustion. To study the influence of gravity, a specially dedicated reactor ensemble was designed and used in the Microgravity Science Glovebox (MSG) onboard the ISS. In this work, the experiment design is first discussed in terms of the experimental functionality and reactor ensemble integration in the MSG. To investigate microstructure formation, a sample constituted by a cylindrical portion followed by a conical one, the latter being inserted inside a massive copper block, is used. The experiment focused on the synthesis of intermetallic matrix composites (IMCs) based on the Al-Ti-B system. Depending on the composition, different intermetallic compounds (TiAl and TiAl₃) can be formed as matrix phase while TiB2 represents the reinforcing particulate phase. During the ISS mission, six samples with a relatively high green density of 65%TD have successfully been processed. The influence of the composition on the combustion process will be examined.     

Increased biological activity of a recombinant factor IX variant carrying alanine at position +1

In attempts to improve the post-translational modification andprocessing of recombinant factor IX (FIX) we have altered thecDNA sequence encoding pre-pro-FIX using site-directed mutagenesisand have expressed the variant cDNAs in BHK21 cells using avaccinia-virus-derived vector. We find that substitution ofthe tyrosine residue at +1 for an alanine increases the biologicalactivity of the recombinant molecules 2–fold. On the otherhand, substitution of the proline at –3 for a valine resultsin no significant change to the specific activity of the protein.Other alterations to the N-terminus of the FIX proteins, inattempts to mimic other vitamin-K-dependent proteins, resultin the failure to produce a secreted polypeptide. N-terminalsequence analysis of purified recombinant molecules revealsa correlation between specific activity and the efficiency ofcorrect pro-sequence cleavage. -Carboxylation analysis of purifiedrecombinant proteins indicates that each molecule includingunmutated FIX is completely -carboxylated in this system. Thusthe observed increase in biological activity of FIX variantscontaining an alanine at position +1 is not due to increased-carboxylation but, at least in part, to more efficient pro-peptidecleavage.     

Oxygen atom density in capacitively coupled RF oxygen plasma

The density of neutral oxygen atoms was determined in a plasma reactor for surface functionalization of polymer materials. Plasma was created in a stainless steel chamber by capacitively coupled RF generator at 13.56 MHz and adjustable forward power up to 100 W. Measurements were performed with a classical nickel catalytic probe. Systematic measurements were performed at a constant pumping speed, different flow rates from 15 to 100 sccm corresponding to pressures between 30 and 110 Pa, different powers between 40 and 100 W and different probe positions in the discharge chamber. The results showed that the O atom density did not depend much on probe position as long as it was between the powered electrode and grounded housing facing the electrode. The O density depended rather linearly with power at fixed pressure. At low power, the O density did not depend much on pressure, but at high power, it was increasing with increasing pressure. The O density was of the order of 10¹⁹ m⁻³ and increased slightly over 10²⁰ m⁻³ at the highest power and pressure. The results were explained by gas phase and surface reactions.     

Influence of the anionic part of the stabilizer on electroless nickel-boron plating

Selectivity and smooth operation of electroless nickel plating require that a stabilizing agent is used. It operates by blocking catalytic activity on unwanted germination sites and regulating the activity of the substrate. In the case of alkaline electroless nickel-boron plating systems, which use sodium (or potassium) borohydride as reducing agent, lead and thallium salts are the most popular stabilizers. However, there is little knowledge about the way the stabilizer acts. In this study, 4 different lead-based stabilizers (tungstate, sulphate, nitrate and chloride) have been used, all other things left constant, in electroless nickel-boron plating baths. The thickness, composition, roughness, morphology, hardness and structure of all the obtained coatings have been investigated. Chloride led to thinner deposits and the boron content varied between 5.5?wt.% for lead tungstate and 6.5?wt.% for lead nitrate and lead sulphate, with a lead content between 0.2 and 0.25?wt.%. Coatings obtained with a lead tungstate stabilized bath were thicker, harder and contained less boron and lead than the others. This shows the influence of the anionic part of the stabilizing agent on the plating process.     

Optimisation of production conditions for 4-hydroxy-2,6-dioxabicyclo(3,3,0)octan-8-one[1S,4S,5R] by catalytic oxidation

The 4-Hydroxy-2,6-dioxabicyclo(3,3,0)Octan-8-one[1S,4S,5R], monoketone, is obtained by catalytic oxidation of isosorbide—or 2,6-dioxabicyclo(3,3,0)4,8-octandiol[1R,4S,5R,8R]—in an aqueous solution with a stream of oxygen and in the presence of a platinum on carbon catalyst. Setting up sequentially two experimental designs made it possible to study the three main factors which influence the monoketone formation in the case of two reactors of different size and profile. Optimisation of selective and/or quantitative conditions is carried out by comparing response surfaces. Several functional configurations for a discontinuous reactor under agitation are proposed as a function of the constraints chosen.     

Engagement et persuasion par la peur: Vers une communication engageante dans le domaine de la santé.

Evidence from psychological research has shown the importance of fear on attitude and/or behavior change. The experiment hereby quoted tests the influence of commitment (high vs. low) on an attempt of persuasive message for a forthcoming effect, that is, after reading an antialcohol message to subjects. The idea consists in inducing alcohol consumers toward modifying their attitude and behavioral intentions toward alcohol. As expected, the high committed drinkers (i.e., regular drinkers) resist persuasion (on the level of both attitude and intention). The low committed drinkers (i.e., occasional drinkers) do not resist persuasion but adopt further on a more favorable attitude toward alcohol. The drinkers who had read a strongly threatening, yet at the same time strongly reassuring, message express the strongest intention to reduce their alcohol consumption. Results are described with reference to Witte's (1998) extended parallel process model. A new perspective is presented at the end of our paper, that is, toward a "committing communication." (PsycINFO Database Record (c) 2010 APA, all rights reserved)