Molecular simulation for adsorption of chlorinated hydrocarbon in zeolites

Equilibrium and isosteric heat of adsorption for the system of chloroform and USY-type zeolite were studied. The USY-type zeolite (PQ Co., SiO₂/Al₂O₃=70) was used both as a pure crystalline powder and as granulated particles with binder. Chloroform was reagent grade. The adsorption equilibria were measured using a gravimetric method and were expressed as isotherms. A chromatographic method (i.e. pulse response of chloroform through the USY column with helium carrier) was used to get the initial slope of the isotherms. In the simulation, the GCMC method was used to calculate amounts adsorbed for various conditions. FF parameters were confidently applied. And modified structure model was effective for simulation. This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between August 19 and 21, 1999.     

Anelastic properties of aluminium thin films on silicon cantilevers

Thin films (thickness 40 to 250 nm) of Al on microstructurized Si substrates have been investigated by the vibrating-reed technique (typical frequencies 100 Hz to 10 kHz) with strain amplitudes in the range of 10⁻⁷ to 10⁻⁴ and for temperatures up to 850 K. The combined evaluation of flexural and torsional vibrations permits to separate the complex shear modulus and biaxial modulus of the thin layer, which helps to identify the damping mechanisms. For Al thin films with thickness <200 nm, in addition to the well-known damping peak due to grain boundary sliding (peak temperature about 370 K), a further maximum of damping has been observed around 600 K, the nature of which is discussed.     

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Effect of substrate adaptation on the microbial fermentation and microbial composition of faecal microbiota of weaning piglets studied in vitro

The in vitro cumulative gas production technique can be used to assess microbial activity of a complex community, in relation to fermentation of a particular energy source. Therefore, in combination with an in vivo study to examine the effects of two different diets for weaning piglets, microbial activities of faeces were compared from animals on the two different diets. The two diets were: CHO diet [containing added fermentable carbohydrates, including sugarbeet pulp (SBP) and wheat starch (WST)], and control diet without any added fermentable carbohydrates. Neither diet contained antibiotics or extra added copper. Twenty‐four piglets were selected from 12 litters (two per litter), weaned at 4 weeks of age (neither creep feeding nor any antibiotic treatment before and during the study), and introduced to one of the two diets. After 9 days on the diet, faecal samples were collected from selected animals, and tested for their activity in terms of gas production kinetics, and end‐products such as volatile fatty acids, ammonia and dry matter disappearance of the two test substrates SBP and WST. The bacterial diversity was also analysed before and after in vitro fermentation using denaturing gradient gel electrophoresis analysis of amplified 16S rRNA genes. There were differences both in kinetics and end‐products of the substrates. More interestingly, significant differences were detected between inocula, although mainly in terms of fermentation kinetics of the two substrates. With the CHO inoculum, SBP was fermented faster than with the control, while this effect was reversed for WST. Significantly higher diversity, as measured by DGGE fingerprint analysis, was detected in the microbial community enrichment on SBP as compared with WST at the end of fermentation. The difference between the kinetics of SBP compared with WST fermentation by faecal microbiota from the CHO diet fed piglets suggests better adaptation to SBP fermentation than to WST fermentation. The WST fermentation was more unexpected, given that a significant amount of starch is known to be fermentable by the small intestinal microbiota. It was concluded that the microbial community composition and activity in the GIT may be changed in response to diet, and that this change can be detected in vitro. Copyright © 2005 Society of Chemical Industry     

The potential of perylene bisimide derivatives for the solubilization of carbon nanotubes and graphene

Carbon nanotubes and graphene are outstanding materials of the 21st century with a broad spectrum of applications. However, major challenges are faced such as the intrinsically low solubility of both sp2 carbon allotropes. To overcome this hurdle the potential of noncovalent functionalization is summarized with a special focus on the establishment of the perylene bisimide unit as aromatic anchor to the graphitic surface. Rational surfactant design is unmasked as the key to solubilization of the carbon allotropes, while at the same time tailoring their surface properties, or even electronic properties in a fully reversible fashion.