Solid state intercalation of barium into poly(para-phenylene): TEM, EELS and ESR characterizations

Compressing together divided barium and poly(para-phenylene) results in the intercalation of the metal into the polymer. Electron energy loss spectroscopy (EELS) analysis indicates that an intercalation level of 0.24 barium ions per phenyl unit can be achieved and that the oxidation state of the intercalated barium is rather +2 (Ba²⁺). Both transmission electron microscopy and electron spin resonance studies show that the distribution of the intercalant in the polymer is very inhomogeneous.     

Comparison of the evaluation of the carbon content in solid solution in extra-mild steels by thermoelectric power and by internal friction

The comparison of the evaluation of the carbon content in solid solution in extra-mild steels by thermoelectric power (TEP) and by internal friction (IF) showed the existence of a population of carbon atoms, which is not detected by IF but is visible by TEP. This population, which contributes to the strain ageing, could be constituted of carbon atoms in interaction with substitutional atoms.     

Requirement of protein synthesis for group I mGluR-mediated induction of epileptiform discharges

Picrotoxin (50 microM) elicited rhythmic synchronized bursting in CA3 pyramidal cells in guinea pig hippocampal slices. Addition of the selective group I metabotropic glutamate receptor (mGluR) agonist (S)-3,5-dihydroxyphenylglycine (25 microM) elicited an increase in burst frequency. This was soon followed by a slowly progressive increase in burst duration (BD), converting the brief 250-520 ms picrotoxin-induced synchronized bursts into prolonged discharges of 1-5 s in duration. BD was significantly increased within 60 min and reached a maximum after 2-2.5 h of agonist exposure. The protein synthesis inhibitors anisomycin (15 microM) or cycloheximide (25 microM) significantly impeded the mGluR-mediated development of the prolonged bursts; 90-120 min of agonist application failed to elicit the expected burst prolongation. By contrast, the mGluR-mediated enhancement of burst frequency progressed unimpeded. Furthermore, protein synthesis inhibitors had no significant effect on the frequency or duration of fully developed mGluR-induced prolonged discharges. These results suggest that the group I mGluR-mediated prolongation of synchronized bursts has a protein synthesis-dependent mechanism.     

Color stability of heat-treated wood during artificial weathering

The color change of wood after exposure to UV light may produce aesthetical damages. The stability of the color to light exposure is an important issue. This study describes experiments of testing the color stability of heat-treated wood samples. Heat treatment was done at 240°C during 2 hours, under nitrogen. Heat-treated samples of ash, beech, maritime pine and poplar heartwood were exposed to UV-light (QUV equipped with fluorescent lamps UVA-340) during 835 hours. Color measurements during accelerated weathering were made at intervals throughout the test period. The results are presented in ΔE and L* a* b* coordinates according to the CIELab system. The experiments show that the color stability for heat-treated wood is better during the 835 hours of exposure when compared to untreated wood. The properties of heat treated wood (lignin modifications, and monomers of phenolic compounds) are probably involved in the retified wood resistance against UV light under experimental conditions.     

Electrochemical behaviour of lead chloride (PbCl2) in dimethylsulphoxide (DMSO)—II. a chronopotentiometric study

In our earlier electrode kinetic studies (chronopotentiometric) of lead chloride (PbCl₂) in dimethylsulfoxide (DMSO), the points in the plot of E, vs log (τ^1/2 ? t^1/2) were linear in the form of a wave. This situation was similar to that observed by Delahay in the chronopotentionmetric reduction of chromate ion (aqueous medium) and thought to be due to a prekinetic step. To verify the presence of a prekinetic step in our case a survey of iτ^1/2vs i for a wider range of lead chloride concentration was started. But a distortion observed in the initial part of the curve (from 4·0 mM PbCl₂) was another point of similarity with that of chromate ion. This led us to consider the polarographic and chronopotentiometric reduction behaviour of CrO^2?₄ in two different electrolytes sodium hydroxide and sodium carbonate. Such considerations justify the presence of a prekinetic step in electrochemical reduction of chromate. Such a prekinetic step, probably the dissociation of PbCl₂, is verified and Kk^1/2₂ values for this coupled chemical reaction are determined according to the transition time expressions of Delahay and Dracka.     

Über Geschichte, physikalische Grundlagen und Applikationen der RFID-Technologie

Die Technologie der kontaktlosen Identifikation (RFID – Radio Frequency Identification) ist derzeit am Sprung, einer der bedeutendsten Industriezweige zu werden. War es in den 1990ern die rasante Entwicklung im Bereich der mobilen Kommunikation, so sind es derzeit die enormen Entwicklungen im Bereich RFID, welche einerseits industrielle Prozesse revolutionieren und andererseits auch in unser t?gliches Leben Einzug halten. Ziel der vorliegenden Ausführungen ist es, die historische Entwicklung dieser vergleichsweise jungen Technologie aufzuzeigen, die physikalischen Grundlagen bestehender Konzepte zu vermitteln, die Vielfalt von m?glichen Anwendungen und Einsatzbereichen zu beschreiben sowie die technischen Herausforderungen zu verdeutlichen.      

Arts—an automated requirements traceability system

Management of the hundreds or thousands of requirements associated with a large aerospace system is a tedious, error-prone process. Automated Requirements Traceability System (ARTS) has been developed to automate this process. ARTS is a bookkeeping program that operates on a data base consisting of system requirements and their attributes. It provides upward and downward traceability in a hierarchical structure, as well as data base management and output operations on any requirement-related attributes selected by the user. ARTS is currently implemented on the UNIVAC 1110, DEC VAX-11/780, and IBM computers.