Tungsten insulated susceptor cup for high temperature induction furnace eliminates contamination

METILUR /Materials Experimental Tungsten Induction Laboratory Unit Replacement/ is an improved, unitized design of a susceptor cup and shielding that uses only one type of construction material /tungsten/ which eliminates contamination. Cycling runs can be accomplished with METILUR

Induction furnace with perforated tungsten foil shielding Patent

Induction heating of metallurgical specimens to high temperatures in coil furnac

Fracture simulation for zirconia toughened alumina microstructure

Purpose - The purpose of this paper is to describe finite element modelling for fracture and fatigue behaviour of zirconia toughened alumina microstructures. Design/methodology/approach - A two-dimensional finite element model is developed with an actual $Al{_2}O{_3}$ - 10 vol% $ZrO{_2}$ microstructure. A bilinear, time-independent cohesive zone law is implemented for describing fracture behaviour of grain boundaries. Simulation conditions are similar to those found at contact between a head and a cup of hip prosthesis. Residual stresses arisen from the mismatch of thermal coefficient between grains are determined. Then, effects of a micro-void and contact stress magnitude are investigated with models containing residual stresses. For the purpose of simulating fatigue behaviour, cyclic loadings are applied to the models. Findings - Results show that crack density is gradually increased with increasing magnitude of contact stress or number of fatigue cycles. It is also identified that a micro-void brings about the increase of crack density rate. Social implications - This paper is the first step for predicting the lifetime of ceramic implants. The social implications would appear in the next few years about health issues. Originality/value - This proposed finite element method allows describing fracture and fatigue behaviours of alumina-zirconia microstructures for hip prosthesis, provided that a microstructure image is available

A Global Analysis of Dark Matter Signals from 27 Dwarf Spheroidal Galaxies using 11 Years of Fermi-LAT Observations

We search for a dark matter signal in 11 years of Fermi-LAT gamma-ray data from 27 Milky Way dwarf spheroidal galaxies with spectroscopically measured $J$-factors. Our analysis includes uncertainties in $J$-factors and background normalisations and compares results from a Bayesian and a frequentist perspective. We revisit the dwarf spheroidal galaxy Reticulum II, confirming that the purported gamma-ray excess seen in Pass 7 data is much weaker in Pass 8, independently of the statistical approach adopted. We introduce for the first time posterior predictive distributions to quantify the probability of a dark matter detection from another dwarf galaxy given a tentative excess. A global analysis including all 27 dwarfs shows no indication for a signal in nine annihilation channels. We present stringent new Bayesian and frequentist upper limits on the dark matter cross section as a function of dark matter mass. The best-fit dark matter parameters associated with the Galactic Centre excess are excluded by at least 95% confidence level/posterior probability in the frequentist/Bayesian framework in all cases. However, from a Bayesian model comparison perspective, dark matter annihilation within the dwarfs is not strongly disfavoured compared to a background-only model. These results constitute the highest exposure analysis on the most complete sample of dwarfs to date. Posterior samples and likelihood maps from this study are publicly available.Comment: 27+5 pages, 10 figures. Version 2 corresponds to the Accepted Manuscript version of the JCAP article; the analysis has been updated to Pass 8 R3 data plus 4FGL catalogue, with one more year of data and more annihilation channels. Supplementary Material (tabulated limits, likelihoods, and posteriors) is available on Zenodo at https://doi.org/10.5281/zenodo.261226

On a Road to Nowhere: Implied Declarations of Inconsistency and the New Zealand Bill of Rights Act

This article explores recent case law touching on the suggestion that the New Zealand courts have an implied power to formally declare that legislation is inconsistent with the rights and freedoms contained in the New Zealand Bill of Rights Act 1990. The article concludes from this case law that the prospects for the development of a formal declaratory jurisdiction of this kind in New Zealand are, if anything, receding. Further, although the Supreme Court's decision in R v Hansen [2007] 3 NZLR 1 affirms the power of the New Zealand courts to informally "indicate" the existence of such legislative inconsistencies, early indications suggest that it is unlikely that this power will be exercised on a routine basis. In the absence of legislative reform, any "dialogue" over human rights between the New Zealand courts and the political branches of government is likely to continue to be far more sporadic and sotto voce than in those countries that have legislated for an express declaration of inconsistency power

Degradation of alumina and zirconia toughened alumina (ZTA) hip prostheses tested under microseparation conditions in a shock device

This paper considers the degradation of alumina and zirconia toughened alumina vs. alumina for hip implants. The materials are as assumed to be load bearing surfaces subjected to shocks in wet conditions. The load is a peak of force; 9 kN was applied over 15 ms at 2 Hz for 800,000 cycles. The volumetric wear and roughness are lower for ZTA than for alumina. The long ZTA ageing did not seem to have a direct influence on the roughness. The ageing increased the wear volumes of ZTA and it was found to have a higher wear resistance compared to alumina.Comment: International Conference on BioTribology (ICoBT 2011), Londres, 18 au 21 septembre 2011, Londres : United Kingdom (2011

Predicting the steady state thickness of passive films in order to prevent degradations of implant

Some implants have approximately a lifetime of 15 years. The femoral stem, for example, should be made of 316L/316LN stainless steel. Fretting corrosion, friction under small displacements, should occur during human gait, due to repeated loadings and un-loadings, between stainless steel and bone for instance. Some experimental investigations of fretting corrosion have been practiced. As well known, metallic alloys and especially stainless steels are covered with a passive film that prevents from the corrosion and degradation. This passive layer of few nanometers, at ambient temperature, is the key of our civilization according to some authors. This work is dedicated to predict the passive layer thicknesses of stainless steel under fretting corrosion with a specific emphasis on the role of proteins. The model is based on the Point Defect Model (micro scale) and an update of the model on the friction process (micro-macro scale). Genetic algorithm was used for finding solution of the problem. The major results are, as expected from experimental results, albumin prevents from degradation at the lowest concentration of chlorides; an incubation time is necessary for degrading the passive film; under fretting corrosion and high concentration of chlorides the passive behavior is annihilated

New Catalytic Reactions in Carbohydrate Chemistry

Carbohydrates or sugars are some of the most diverse and abundant biological molecules. They are involved in a multitude of processes in the body such as fertilization, cell-cell communication, and cancer metathesis. Because of these vital functions, the study of sugars is rapidly growing field. The field however is limited due to the complex nature of sugars which results in difficulties in obtaining large quantities for study. Protecting group manipulation is a large emphasis area in carbohydrate chemistry due to the need to selectively protect different functional groups of each molecule during synthesis. Catalytic and selective cleavage of protecting groups is a growing area in the field of carbohydrates as current methods are time-consuming and require large excess of reagents. Picoloyl ester is becoming a common protecting group due to its ability to provide a powerful stereodirecting effect in glycosylation reaction. Chapter 2 details the development of a new catalytic approach to remove the picoloyl group in a highly chemoselective manner. Protecting group manipulation is only one part of carbohydrate synthesis. New catalytic methods for glycosylation, a fundamental reaction for connecting two sugar units, are also needed. Chapter 3 describes our recent discovery that catalytic FeCl3 can efficiently activate glycosyl chloride to produce disaccharides in respectable yields in 30 min – 16 h. Chapter 4 further elaborates upon the topic of chemical glycosylation. Described herein is the application of a cooperative Ag2O and triflic acid catalysis to glycosidation of glycosyl chlorides. Fast reaction times and near quantitative yields are the main traits of this method. Lastly, Chapter 5 combines findings described in the previous chapters into development of a new superior platform for oligosaccharide synthesis. Currently used strategies for oligosaccharide synthesis are time consuming, inefficient, and may lead to low yields of oligosaccharides. By combining the catalytic picoloyl group cleavage and activation of glycosyl chlorides using FeCl3 we developed a reverse orthogonal synthetic strategy which combined protecting group cleavage and activation of glycosyl donors in one step. We then showcase how efficiently this concept works for the rapid assembly of oligosaccharide sequences