Atom probe investigations on temper embrittlement and reversible temper embrittlement in S 690 steel weld metal

Severe embrittlement was observed in weld material of a brand new penstock of a huge hydro power plant. Temper embrittlement (TE) was found as root case of embrittlement. Reversible temper embrittlement (RTE) treatment characterised by a short-time heating at about 600°C, by which the toughness of embrittled weld material can significantly be recovered, was qualified and successfully applied in the plant. Basic investigations were performed to explain the embrittlement as well as the de-embrittlement effect. By the application of high resolution analytics as Atom Probe Tomography (APT) applied on TE as well as on the RTE-treated material, revealed phosphorus segregation in the grain boundaries as root cause of embrittlement. By application of RTE treatment the APT results revealed, that the phosphorus segregation in the grain boundaries disappeared. The mechanism of this behaviour can be explained by referring the McLean [Grain boundaries in metals. Oxford: Clarendon Press; 1957] based grain boundary equilibrium segregation of phosphorous. During RTE treatment, which occur at higher temperatures (600°C) that segregation (which starts during cooling at about 550°C), desegregation occurs. During this higher temperature, the diffusion is much faster than segregation producing the fast recovery of toughness.     

Carriers in Cell-Based Therapies for Neurological Disorders

There is a pressing need for long-term neuroprotective and neuroregenerative therapies to promote full function recovery of injuries in the human nervous system resulting from trauma, stroke or degenerative diseases. Although cell-based therapies are promising in supporting repair and regeneration, direct introduction to the injury site is plagued by problems such as low transplanted cell survival rate, limited graft integration, immunorejection, and tumor formation. Neural tissue engineering offers an integrative and multifaceted approach to tackle these complex neurological disorders. Synergistic therapeutic effects can be obtained from combining customized biomaterial scaffolds with cell-based therapies. Current scaffold-facilitated cell transplantation strategies aim to achieve structural and functional rescue via offering a three-dimensional permissive and instructive environment for sustainable neuroactive factor production for prolonged periods and/or cell replacement at the target site. In this review, we intend to highlight important considerations in biomaterial selection and to review major biodegradable or non-biodegradable scaffolds used for cell transplantation to the central and peripheral nervous system in preclinical and clinical trials. Expanded knowledge in biomaterial properties and their prolonged interaction with transplanted and host cells have greatly expanded the possibilities for designing suitable carrier systems and the potential of cell therapies in the nervous system.     

Concentrations and health hazards of polycyclic aromatic hydrocarbons in selected commercial brands of milk

The concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) were determined in twenty popular commercial brands of milk in the Nigerian market after saponification with ethanolic KOH and cyclohexane extraction and clean up using a gas chromatography with flame ionization detection. The concentrations of the Σ16 PAHs in these brands of milk ranged from 15.6 to 1,711.8 μg kg^?1. The dominant PAH compounds in these brands of milk were 3-and-4-rings PAHs. The dietary intake of BaP, PAH2, PAH4 and PAH8 were 0–53.9 and 0–369.6 ng kg^?1 bw day^?1 respectively. Using these indicators for occurrence and effects (BaP, PAH2, PAH4 and PAH8) PAHs in food, the margin of exposure were <10,000 in 15–30 % of the brands.     

Strengthening and mechanical stability mechanisms in nanostructured bainite

Understanding the main relationships between the microstructure parameters controlling the strength and ductility of low temperature bainitic microstructures is of considerable importance for further development of these grades. Although the microstructure essentially consists of solely two phases, bainitic ferrite and retained austenite, the complexity of the different microstructural characteristics, the natural consequence of its unique transformation mechanisms, might not provide with one unique answer, but a set of several parameters interdependent among them. This paper will deal with some of these relationships’ microstructure properties, strength, and ductility, with special emphasis in the mechanical stability (TRIP effect) of retained austenite.     

Kinetic Resolution of 1‐Biaryl‐ and 1‐(Pyridylphenyl)alkan‐1‐ols Catalysed by the Lipase B from Candida antarctica

Lipase B from Candida antarctica (CAL‐B) catalyses the highly enantioselective (E>200) transesterification of some 1‐biaryl‐2‐yl‐, ‐3‐yl‐, and ‐4‐ylethanols and ‐propan‐1‐ols, as well as 1‐(o‐, m‐, and p‐pyridylphenyl)ethanols, 6 , with vinyl acetate, Kazlauskas' rule being obeyed in all cases. meta and para‐Substituted substrates were transformed within several hours (conversion degree ranging from 23–50%), reaction rates for propan‐1‐ol derivatives being slower than those for ethanol derivatives. Transesterifications of ortho‐substituted alcohols took several days and were accompanied by a chemoenzymatic side reaction: the formation of another acetate derived from the hemiacetal between 6 and acetaldehyde coming from vinyl acetate. This side reaction was suppressed in the presence of isopropenyl acetate as acyl donor, conversion degrees for transesterification ranging from 20–40% after ten days (E>200). The usefulness of (R)‐ 6p as ligand in the asymmetric addition of diethylzinc to benzaldehyde was also demonstrated.     

Protective effect of white tea extract against acute oxidative injury caused by adriamycin in different tissues

Adriamycin (ADR) is an anticancer agent that increases oxidative stress in cells. We evaluated the protective effect of the long term consumption of white tea at two different doses against this drug. For this purpose rats were given distilled water (controls), 0.15 mg (Dose 1) or 0.45 mg (Dose 2) of solid tea extract/kg body weight for 12 months. All the animals received an injection of ADR, except half of the control group, which were given an injection of saline solution. This gave four experimental groups: Control (C), C + ADR, Dose 1 + ADR, and Dose 2 + ADR. The antioxidant activity (in liver, heart and brain microsomes) was analysed. White tea consumption for 12 months, at a non-pharmacological dose, reversed the oxidative damage caused by ADR, on both protein and lipid levels in all three organs. The heart recovered its antioxidant activity only at the highest dose of tea.     

On the Treatment of Repeated Observations in Panel Data: Efficiency of Mixed Logit Parameter Estimates

Travel demand models are usually estimated using cross-sectional data. Although the use of panel data has recently increased in many areas, there are still many aspects that have not been fully analyzed. Some examples of unexplored topics are: the optimal length of panel surveys and the resulting issue of how to model panel data correctly in the presence of repeated observations (for example, several trips per week, by people in a panel with waves every six months) and whether, and to which extent, this affects the efficiency of the estimated parameters and their capability to replicate the true situation. In this paper we analyse this issue and test the effect of including journeys made, with the same characteristics, several times in a week. A broad variety of models accounting for fixed parameters but also for random heterogeneity and correlation among individuals were estimated using real and synthetic data. The real data comes from the Santiago Panel (2006–2008), while the synthetic data were appropriately generated to examine the same problem in a controlled experiment. Our results show that having more observations per individual increases the probability of capturing more effects (i.e. different types of heterocedasticity), but having identical observations in a data panel reduces the capability to reproduce the true phenomenon. Consequently, the definition of panel survey length demands us to consider the implicit level of routine (i.e. the proportion of identical observations) in it.