Reliability of reconstructed beta-orientation maps in titanium alloys

This paper demonstrates that parent beta-orientation maps of titanium alloys can reliably be reconstructed from inherited alpha maps in most cases. Important aspects of the calculation that ensure an accurate determination of the parent orientation as well as a reliable restitution of the beta boundaries are discussed. The limits of the reconstruction method, according to the inherited alpha microstructure are also pointed out. Finally, the method is applied to a beta metastable titanium alloy, which contained enough retained beta phase so that its orientation could be measured by EBSD. The comparison between the measured and the reconstructed beta maps shows the efficiency of the method.     

Mechanical behavior characterization of high zirconia fused-cast refractories at high temperature: Influence of the cooling stage on microstructural changes

Today, the high quality level required by new applications of glass, imposes the use of high zirconia refractories (HZ). These are designed to operate in extreme condition and also require control of the making process. Elaborated by a fused cast process followed by a controlled cooling step, these materials exhibit specific thermo mechanical properties related to a microstructure containing monoclinic zirconia dendrites embedded into a silica–alumina glassy phase.The present paper deals with the understanding of damage phenomena at a low scale during the cooling process after cast-fusion. Mechanical characterizations at high temperature are carried out to identify the chronology of the microdamage. Microstructure observations using SEM and EBSD complete thermal experiments and allow to identify main characteristics of microdamage mechanisms. This work was conducted in the framework of a French national research program “NOREV”, aiming to build numerical tools to optimize the casting process of such materials.     

Influence of transformation temperature on microtexture formation associated with α precipitation at β grain boundaries in a β metastable titanium alloy

The influence of transformation temperature on microtexture development associated with α precipitation at β/β grain boundaries (GB) in the near-β Ti17 alloy was studied using electron backscatter diffraction and considering isothermal treatments. For the alloy studied and the temperature range considered, decreasing the transformation temperature decreased the local microtexture strength within each prior β grain because of a larger number of α_WGB colonies (standing for α Widmanstätten GB) formed per β grain, each colony increasing by one the number of α orientations inside each prior β grain. This larger number of α_WGB colonies was a consequence of faster formation along β/β GB of their precursors, the allotriomorphic α_GB grains (standing for α-GB) at lower transformation temperatures, as evidenced by detailed examination of the first stages of α_GB formation. α_GB crystallographic orientations frequently followed a variant selection (VS) criterion based on the alignment of (0 1 1)β//(0 0 0 1)α_GB//(0 1 1)β. From a statistically relevant number of observations, VS was found to be more frequent at a lower transformation duration and a lower temperature, but the effect was not significant enough to influence the final α microtexture, considered at the scale of one prior β grain. α_GB grains that followed the VS criterion emitted two α_WGB colonies on either side of the β/β GB more frequently than those with no particular orientation.     

Conformational properties of a cycle oligosaccharide: cyclotrikis-(1-->6)-[alphaD-glucopyranosyl-(1-->4)-beta-D-glucopyranosy l]

Within a larger environmental health screening program neurobehavioral measures were taken in 384 6-year-old children (mean age 74 months) in the cities of Leipzig, Gardelegen, and Duisburg. Lead concentrations in venous blood samples (PbB) and urinary mercury excretion in 24-h samples (HgU) were measured as markers of environmental exposure by electrothermal AAS. Dependent variables included two subtests from the WISC [vocabulary (V) and block design (BD)] as well as five tests from the NES2 [pattern comparison, pattern memory, tapping, simple reaction time, and the continuous performance test (CPT; child version)]. In addition, visual functions [visual acuity (TITMUS-test) and contrast sensitivity (FACT)] were tested as covariates. The overall average PbB (geometric mean) was 42.5 microg/l (upper 95% value = 89 microg/l). The overall average mercury excretion (HgU) was 0.16 microg/24 h. Whereas no significant or borderline associations between HgU and any of the target variables was found, significant negative associations were observed between PbB and verbal intelligence (WISC vocabulary but not WISC Block Design) and false-positive responses (false alarms), as well as false-negative responses (miss) in the CPT. Whereas parental education was the most important confounder for WISC performance, visual contrast sensitivity and computer familiarity also proved predictive for performance in several computer-based NES subtests. It is concluded that non-IQ measures, namely measures of sustained attention, are negatively affected in children with 95% of blood-lead levels below 90 microg/l, even after adjustment for intelligence and contrast sensitivity, whereas the causative role of lead in altering IQ functions remains somewhat equivocal, because important covariates could not be controlled for.     

Study of the β-α phase transformations of a Ti-64 sheet induced from a high-temperature β state and a high-temperature α + β state

The room-temperature α textures of Ti-64 sheets, inherited from the β-α phase transformation of high-temperature β textures of the material in the β and α + β fields, respectively, have been studied. The corresponding high-temperature β textures were also determined by a method developed in our laboratory. The knowledge of the high-temperature β textures allowed us to discuss the variant selections through transformation modeling. As a result, a variant selection occurs in the presence of the stable α grains of the α + β field.     

An advanced approach to reconstructing parent orientation maps in the case of approximate orientation relations: Application to steels

Reconstructions allow the evaluation of the microtexture before phase transformation from that measured by EBSD after phase transformation. Even though they have been applied successfully to titanium alloys and other materials, their application to reconstruction of austenite in steels requires care. This paper details first a new approach to crystallographic reconstruction, which has been designed to meet the necessary requirements in steels. This approach is then validated in two low-carbon steels. The goal is to fix the potential and limits of crystallographic reconstruction when applied to steels. Important recommendations are made to ensure accurate reconstruction.     

Experimentelle und theoretische Untersuchungen an Kohlenwasserstoffen der Formel C5H6: Pyrolyse von Cyclopenta-1,3-dien

Experimental and Theoretical Investigations on Hydrocarbons of the Formula C₅H₆: Pyrolysis of 1,3-Cyclopentadiene The details of high temperature chemistry of the conversion of 1,3-cyclopentadiene (CPD) are unknown. Therefore the pyrolysis of CPD was studied under various reaction conditions in labscale dimension. The attempt to interpret the composition of the reaction products only on the basis of convenient axiomes does not seem satisfactory. For that reason heats of formation and relative stabilities for 25 closed and open shell hydrocarbons of the formula C₅H₆ were calculated using the MINDO/3 procedure. These enthalpy values were used to estimate heats of reactions for selected start steps of the pyrolysis of CPD. The molecular-assisted hydrogen transfer under formation of cyclopentadienyl and cyclopentenyl radicals ought to be one of the most important reaction steps.     

香精为油相液晶乳液的相行为

采用偏光显微镜观察及测定电导率的方法研究了由聚氧乙烯醚失水山梨醇脂肪酸酯(APS)、失水山梨醇脂肪酸酯(SE)、十八醇、油和水组成体系的相行为。结果表明,体系在乳化剂、助乳化剂和油相含量低时可形成水包油型球形层状液晶乳液LO1相,随着助乳化剂和油的含量增加,体系将形成球形层状LO1(2)与平面层状Lβ的混合相,然后转变成油包水型球形层状液晶乳液LO2。当m(APS)∶m(SE)=4∶1时,体系可形成稳定的水包油型及油包水型球形层状液晶乳液。     

How to improve the hygienic quality of forages for horse feeding

BACKGROUND: Improving the hygienic quality of forages for horse nutrition seems to be a reasonable target for decreasing the prevalence of pulmonary diseases. The aim of the experiment was to study the effects of different agricultural practices on the main aero‐allergens contained in forages, including breathable dust, fungi, mycotoxins and pollens. RESULTS: Results showed that the late harvest of hay, a second crop or a haylage production provides a good alternative to increase hygienic quality by reducing fungi contamination and breathable dust content. Barn drying of hay, while having no effect on breathable dust, similarly reduced fungi contamination. In contrast, when hay was harvested at a lower dry mass content (750 g DM kg^?1 versus 850 g DM kg^?1), both breathable dust and fungi contaminations were increased, which could at least be reversed by adding propionic acid just before baling. Zearalenone was detected in different hays, and even in one case, in breathable dust. CONCLUSION: Overall, our data suggest that different approaches can be used to increase forage hygienic quality for horse feeding and thus reduce their exposure to factors involved in equine pulmonary disease. Copyright © 2011 Society of Chemical Industry     

The common 'thermolabile' variant of methylene tetrahydrofolate reductase is a major determinant of mild hyperhomocysteinaemia

Mild hyperhomocysteinaemia is a major risk factor for vascular disease and neural tube defects (NTDs), conferring an approximately three-fold relative risk for each condition. It has several possible causes: heterozygosity for rare loss of function mutations in the genes for 5,10-methylene tetrahydrofolate reductase (MTHFR) or cystathionine-beta-synthase (CBS); dietary insufficiency of vitamin co-factors B6, B12 or folates; or homozygosity for a common 'thermolabile' mutation in the MTHFR gene which has also been associated with vascular disease and NTDs. We quantified the contribution of the thermolabile mutation to the hyperhomocysteinaemic phenotype in a working male population (625 individuals). Serum folate and vitamin B12 concentrations were also measured and their relationship with homocysteine status and MTHFR genotype assessed. The homozygous thermolabile genotype occurred in 48.4, 35.5, and 23.4% of the top 5, 10, and 20% of individuals (respectively) ranked by plasma homocysteine levels, compared with a frequency of 11.5% in the study population as a whole, establishing that the mutation is a major determinant of homocysteine levels at the upper end of the range. Serum folate concentrations also varied with genotype, being lowest in thermolabile homozygotes. The MTHFR thermolabile genotype should be considered when population studies are designed to determine the effective homocysteine-lowering dose of dietary folate supplements, and when prophylactic doses of folate are recommended for individuals.