Autogenous deformation and RH-change in perspective

Autogenous deformation and change of the relative humidity (RH-change) have been described and registered for a century. However, it is only within the last decade that these phenomena have received appreciable attention. The reason for this is that autogenous deformation and autogenous RH-change are phenomena of special importance within high-strength (high-performance) concrete technology, and a significant utilisation of these concretes did not take place until the early 1980s. In the present paper an historical overview of autogenous deformation and RH-change is given. In addition, due to the present status of this research field both terminology and measuring techniques are described in detail. Finally, some expectations for future research in this field are given.     

Dispersion polymerization of styrene in CO2-expanded ethanol

Dispersion polymerization of styrene has been performed in CO₂-expanded ethanol at ≤9 MPa and 70 °C using PVP as stabilizer. The polymerizations proceeded with good colloidal stability, resulting in spherical particles of diameters of ∼2 μm. Pressurization with CO₂ leads to an increase in particle size (∼1 μm in the corresponding CO₂-free system), and a decrease in both polymerization rate and molecular weight. The main effect of CO₂ is proposed to be its influence on the partitioning of monomer between the continuous and the particle phase–the results indicate that CO₂-pressurization causes a reduction in monomer concentration in the particles. Overall, the results are consistent with literature data on the effects of the polarity of the continuous phase in dispersion polymerization of styrene in alcohols and alcohol/water mixtures.     

Characterization of Particulate Matter from Direct Injected Gasoline Engines

The reactivity and reaction kinetics of particulate matter (PM) from direct injected gasoline (GDI) engines has been studied by O₂ and NO₂ based temperature programmed and isothermal step-response experiments, and the PM nano-structure has been characterized using HRTEM. The reactivity of the PM samples collected in filters during on-road driving was found to increase in the following order: Printex U < diesel < gasoline PI ≈ gasoline DI < ethanol for O₂ based combustion. The activation energies for O₂ and NO₂ based oxidation of PM collected from a GDI engine in an engine bench set-up was estimated to 146 and 71 kJ/mol respectively, which is comparable to corresponding values reported for diesel and model soot. Similar nano-structure features (crystallites plane dimensions, curvature and relative orientation) as observed for diesel soot were observed for gasoline PM.     

Evaluation of Gene Expression Knock-Down by Chemically and Structurally Modified Gapmer Antisense Oligonucleotides

We analyzed the effect of modified nucleotides within gapmer antisense oligonucleotides on RNase H mediated gene silencing. Additionally, short hairpins were introduced into antisense oligonucleotides as structural motifs, and their influence on biological and physicochemical properties of pre-structured gapmers was investigated for the first time. The results indicate that two LNA residues in specified positions of the gap flanking regions are sufficient and favorable for efficient knock-down of the β-actin gene. Furthermore, the introduction of other modified nucleotides, i. e. glycyl-amino-LNA−T, 2′-O-propagyluridine, polyamine functionalized uridine, and UNA, in specified positions, also increases the inhibition of β-actin expression. Importantly, the presence of hairpins within the gapmers improves their silencing properties.     

Mechanism and kinetics of the free radical ring-opening polymerization of cyclic allylic sulfide lactones

The polymerization of 7-, 8- and 11-membered lactones, 6-methylene-1,4-oxathiepan-7-one, 3-methylene-1,5-oxathiocan-2-one and 3-methylene-1-oxa-5-thiacycloundecan-2-one in benzene at 70, 40–70 and 40–65 °C, respectively, is presented. All polymerizations proceeded with complete ring-opening up to approximately 25% conversion, where insoluble polymer was formed. Evidence is given attributing polymer double bond loss to crosslinking, although redistribution of the molecular weights via addition to polymer double bonds followed by β-fragmentation also appears to occur for polymerizations of the 8- and 11-membered lactones. Michael adducts of lactones with 2-methyl-2-propanethiol were prepared as models for chain-transfer products of hydrogen abstraction by carbon-centred radicals. Polymerization rates were found to increase marginally with ring size. Arrhenius parameters obtained for the polymerizations of the 8- and 11-membered lactones indicated that the addition step was more important than fragmentation in determining the rate of propagation.     

Antifeedants against <Emphasis Type="Italic">Hylobius abietis</Emphasis> Pine Weevils: An Active Compound In Extract of Bark of <Emphasis Type="Italic">Tilia cordata</Emphasis> Linden

Linden (Tilia cordata) bark was shown to contain an antifeedant effective against the large pine weevil, Hylobius abietis. Soxhlet extraction of inner and outer bark resulted in an extract that showed antifeedant activity in a microfeeding assay. The extract was fractionated by chromatography on silica gel using gradient elution with solvents of increasing polarity. The content of the fractions obtained was monitored by thin layer- and gas chromatography. Fractions of similar chemical composition were merged. Two of the 17 fractions showed antifeedant activity in the microfeeding assay. Nonanoic acid was identified in both of these fractions. Subsequent testing in the microfeeding assay showed that nonanoic acid possessed strong antifeedant activity against H. abietis adults.     

Fast internal dynamics in polyelectrolyte gels measured by dynamic light scattering

Summary Dynamic light scattering was used to investigate the dynamics of sodium poly(styrene sulfonate) and fully neutralized poly(acrylic acid) gels as a function of the degree of swelling and weight ratio of cross-linking agent. It was shown that the collective diffusion coefficient increases with increasing degree of swelling and that the diffusion coefficient shows stronger concentration dependence than predicted by scaling arguments. For gel samples measured at the swelling equilibrium, the diffusion coefficient increases with increasing gel concentration for both gel systems.     

Phase transformations in face centered cubic (Al0.32Cr0.68)2O3 thin films

Face centered cubic (Al_0.32Cr_0.68)₂O₃ thin films have been annealed in the temperature range of 500–1000 °C during 2–8 h. The fcc structure of the film remains intact when annealed at temperatures up to 700 °C for 8 h. X-ray diffraction and transmission electron microscopy show the onset of phase transformation to corundum phase alloys in the sample annealed at 900 °C for 2 h, where annealing at 1000 °C for 2 h results in complete phase transformation to α-(Al_0.32Cr_0.68)₂O₃. In-plane and out-of-plane line scans performed in EDX TEM and θ/2θ XRD patterns did not show any phase separation into α-Cr₂O₃ and Al₂O₃ prior and after the annealing. The apparent activation energy of this process is 380–480 kJ/mol as determined by the Johnson–Mehl–Avrami model.