An aspect of selecting resolving agents: The role of differences in molecule length in diastereomeric salt resolutions

In the course of 49 individual experiments of diastereomeric salt resolution we have examined the effect of the difference between the racemic and resolving agent molecule lengths on the resolution. We concluded that using resolving agents with the molecule length differing by 3 to 6 from the racemic molecule produces the best result.     

Development of a pressure–volume–temperature measurement method for thermoplastic materials based on compression injection molding

The pressure–volume–temperature (pvT) relationship of polymers is vitally important information in designing and manufacturing polymers. Because of the special behavior of polymers, however, it is extremely difficult to accurately measure the data in a way that matches the thermal conditions of injection molding, which is one of the most widely used processing methods. As neither widely used, commercially available measuring devices, nor special equipment mentioned in the literature can fully satisfy this need, it was decided to build a new device able to determine the pvT relationship during injection molding of the polymer. The new device consists of a special mold that can be used on an injection molding machine and a data collection system connected to it. With the help of this device, pvT data can be measured during processing according to the thermal conditions of injection molding, and also considerably faster, and even in an industrial setting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41140.     

Homology modelling and molecular dynamics studies of human placental tissue protein 13 (galectin-13)

The primary structure of the newly sequence analysed placentaltissue protein 13 (PP13) was highly homologous to several membersof the ß-galactoside-binding S-type lectin (galectin)family. By homology modelling, the three-dimensional structureof PP13 was built based on high-resolution crystal structuresof homologues and also their characteristic `jellyroll' foldwas found in the case of PP13. Our model has been depositedin the Brookhaven Protein Data Bank. By multiple sequence alignmentand structure-based secondary structure prediction, we underlinedthe structural similarity of PP13 with its homologues. The secondarystructure of PP13 was identical with `proto-type' galectinsconsisting of a five- and a six-stranded ß-sheet,joined by two     

A new residual stress distribution for hot-rolled I-shaped sections

During the procedure of manufacturing structural steel profiles the considerable temperature changes cause residual stresses in the material. These stresses can have a significant effect on the stability resistance of structures consisting of such profiles. Therefore engineers have paid special attention to the consideration and modelling of residual stresses in the comprehensive research into column buckling. They developed several stress distribution forms based on experimental and/or theoretical results, which worked well in column buckling problems. However, when the member has twisting displacements-e.g. in the case of lateral-torsional buckling-these stress distributions can lead to malfunction, because they do not satisfy certain equilibrium equations connected with torsion and warping of the profile. In order to avoid this problem a new stress pattern is proposed which satisfies all the equilibrium equations, thus being applicable in stability problems including torsional and warping effects.     

A polymerizable GFP variant

Flagellin has the ability to polymerize into long filaments under appropriate conditions. Our work aims at the construction of flagellin-based fusion proteins which possess polymerization ability and preserve the functional properties of the fusion partner as well. The hypervariable D3 domain of Salmonella flagellin, containing residues 190-283, is a good target for genetic engineering studies since it can be extensively modified or removed without disturbing the self-assembling ability. In this work a fusion construct of flagellin and the superfolder mutant of the green fluorescent protein were created by replacing D3 with superfolder green fluorescent protein (GFP). The obtained GFP variant was capable of forming stable, highly fluorescent filamentous assemblies. Our results imply that other proteins (enzymes, binding proteins, etc.) can also be furnished by polymerization ability in a similar way. This approach paves the way for the construction of multifunctional tubular nanostructures.     

Comparison of diffusion of fructo-oligosaccharide components during vacuum impregnation and osmotic dehydration

The osmotic behaviour of fructo-oligosaccharides was investigated during osmotic dehydration of apple cubes. The effect of vacuum impregnation on discrete diffusion coefficient (D _eff) of oligomers was scrutinised. D _eff were determined using the solution of Fick’s unsteady-state diffusion equation developed by Rastogi and Raghavarao. The moisture content decreases logarithmically irrespective of the type of treatment. The applied vacuum does not influence the rate of decrease of moisture content, but it reduces the water content. There are not significant differences among the D _eff of oligomers. Vacuum impregnation has no effect on D _eff values, which are in narrow range of the order of 10⁻⁹ m² s⁻¹ in the observed set of unit operation parameters. The prediction by the used model is acceptable in all cases especially in traditional osmotic dehydration, where the relative standard deviation (RSD) is less than 10%, and it also demonstrates the altered mechanism of vacuum impregnation by the increased RSD values.     

Novel instrument and method for the investigation of small permeation fluxes of gases through different membranes

In this study a new permeation measurement equipment is presented which is shown to be capable of measuring low and high gas fluxes through different membranes. The new membrane support system which is introduced here is suitable for thin membranes (>10 μm) and is expected to provide more accurate results than the design used in earlier permeation measurements.     

Effect of filler dispersion on the electrical conductivity and mechanical properties of carbon/polypropylene composites

Conducting carbon/polypropylene composites containing a mixed filler of crystalline natural graphite powder, carbon black, and multiwalled carbon nanotubes have been prepared. The effect of the filler dispersion on the electrical conductivity and mechanical properties has been studied. Keeping the graphite content constant and increasing the ratio of carbon black to nanotubes, the conductivity and the flexural modulus increased linearly at different graphite contents. Graphite aggregates on the cross sections were analyzed by optical microscopy to characterize the dispersion of graphite. The results of the optical microscopy studies showed that the dispersion of graphite is affected by the composition and amount of the nanofiller system. Based on the observations simplified morphological models were set up, that allowed to explain the change in the electrical and mechanical properties of the composites of different compositions. POLYM. COMPOS., 34:1195–1203, 2013. © 2013 Society of Plastics Engineers