Amide-modified poly(butylene terepthalate): thermal stability

The thermal stability of a poly(ester amide) copolymer (PBTA) based on poly(butylene terephthalate) (PBT) and nylon-4,T with the diamide of butanediamine and dimethyl terephthalate (N,N′-bis(p-carbomethoxybenzoyl)butanediamine) and homopolymer PBT was studied. The development of inherent viscosity and endgroup concentration was determined during prolonged condensation reactions at 255–275°C. Analysis of the kinetics lead to degradation rate constants for PBT and PBTA with 20 mol% amide (PBTA20). The degradation rate of PBTA20 was comparable to that of PBT, thus β-elimination of the ester groups is the main degradation mechanism in PBTA. At high temperatures ester—amide interchange reactions also take place in PBTA. The change in the melting temperature of PBTA has been related to the decreasing uniformity of the amide segment length. The decomposition was further studied by thermogravimetry and mass spectrometry

A novel method for the fabrication of freestanding PZT features on substrates

A simple and cheap micromoulding fabrication route was developed to prepare freestanding piezo active features. Dimensions as small as 200 μm by 200 μm and 40 μm high were successfully fabricated via a replication technique. The lead zirconate titanate features were thoroughly characterized using SEM, EDX and XRD analysis. The properties of the features were influenced by several factors like the type of substrate, sintering temperature and sintering atmosphere. Features prepared on alumina substrates and sintered in lead atmosphere displayed a structure with reproducible dimensions. Next to that they were low in porosity and had a comparable composition with respect to the starting powder. The remanent polarization of the lead zirconate film was 12.3 μC/cm2 and the coercive field was 8.7 kV/cm

Exploring the use of Acidithiobacillus Ferrooxidans for the removal of Sulphides from Tarnished Silver

Tarnished silver objects contain a black layer of silver sulfide. Current cleaning methods are not suitable for fragile objects, therefore, this exploratory study set out to develop a new biology-based method to clean silver. The extremophile bacterium Acidithiobacillus ferrooxidans was considered the most promising candidate, because of its ability to oxidize metal sulfides. The bacterium indirectly removed silver sulfide from tarnished silver coupons, through the generation of ferric iron. However, this procedure etched the silver. It was investigated whether A. ferrooxidans was able to directly oxidize silver sulfide in the absence of iron. However, no removal of silver sulfide was observed

Effect of temperature on sex expression in onion (Allium cepa L.).

At the onset of bolting, eleven populations of the variety Wolska were placed in the greenhouse at constant temperatures of 14, 17, 20 or 23 deg C. The percentage of male-fertile plants increased with increasing temperature, the critical temperature appearing to be 17 deg C. The transference of plants from outside to a constant temperature of 14 deg C, three or six weeks after the initiation of bolting, showed the effect of temperature to decrease with time, suggesting that induction of male sterility occurs in the early stages of bolting. Observations on an unspecified number of A and B lines of the variety Rijnsburg at 14, 20 and 23 deg C indicated that instability of sex expression occurs only in B lines. (Abstract retrieved from CAB Abstracts by CABI’s permission

Biomethanol from Glycerol

Medical bioinformatic