Using of ultrasonic methods for determination of the elastic moduli on the Ti-Ni based alloys

The presented work is focused on the determination of elastic constants of selected alloys of the systems Ni-Ti and Ni-Ti-Cu with use of ultrasonic methods. Sample preparation was carried out using VIM in graphite crucible in combination with pouring into graphite mould. The prepared samples were appropriately heattreated, polished into the desired shape and subjected to measurement of density and then to ultrasonic measurements. In addition to conventional methods, such as mechanical tests, also less known methods are applied. Among the specific methods we can mention dynamic mechanical analysis, dynamic super microhardness measurement, electro acoustic resonance or ultrasonic test.The group of thus tested materials includes also Ti alloys

Investigation of physical properties of tungsten-based single crystals using an ultrasonic method

Using an ultrasonic method, the measurement of longitudinal and transversal velocities v of ultrasonic waves in the major crystallographic directions of pure-tungsten single crystals and tungsten single crystals alloyed with Ta and Mo was performed. Single crystals with a [110] crystallographic orientation were prepared by plasma-arc melting. Crystal density was also measured. Crystal elastic constants Cij, anisotropy factors A, Young’s modulus E, shear modulus G and bulk modulus B for the given crystallographic directions, and the mean values of the longitudinal and transversal velocities of the ultrasound according to the Fochtu-Roisu-Chilly method, Young’s modulus, shear modulus, Poisson’s ratio and Debye temperature were calculated from the obtained data. The measurement of ultrasound rates was realized by means of a pulse apparatus with a frequency of 10 MHz to 30 MHz. It was found that the alloying of pure tungsten with the elements such as tantalum and molybdenum led to a decrease in the average magnitudes of v, Cij, and B over various crystallographic and polarization directions, as well as the magnitude of . The effects of the alloying elements on the elastic properties of tungsten crystals were identical. It may be concluded on the basis of the obtained results that the ultrasonic method can be used for the quality control of the purity of tungsten single crystals and tungsten low-alloyed alloys by measuring the attenuation effects of ultrasound waves in various parts of the tested samples.Web of Science48682682

Fragmentation of pooled PCR products for highly multiplexed TILLING

Improvements to massively parallel sequencing have allowed the routine recovery of natural and induced sequence variants. A broad range of biological disciplines have benefited from this, ranging from plant breeding to cancer research. The need for high sequence coverage to accurately recover single nucleotide variants and small insertions and deletions limits the applicability of whole genome approaches. This is especially true in organisms with a large genome size or for applications requiring the screening of thousands of individuals, such as the reverse-genetic technique known as TILLING. Using PCR to target and sequence chosen genomic regions provides an attractive alternative as the vast reduction in interrogated bases means that sample size can be dramatically increased through amplicon multiplexing and multidimensional sample pooling while maintaining suitable coverage for recovery of small mutations. Direct sequencing of PCR products is limited, however, due to limitations in read lengths of many next generation sequencers. In the present study we show the optimization and use of ultrasonication for the simultaneous fragmentation of multiplexed PCR amplicons for TILLING highly pooled samples. Sequencing performance was evaluated in a total of 32 pooled PCR products produced from 4096 chemically mutagenized Hordeum vulgare DNAs pooled in three dimensions. Evaluation of read coverage and base quality across amplicons suggests this approach is suitable for high-throughput TILLING and other applications employing highly pooled complex sampling schemes. Induced mutations previously identified in a traditional TILLING screen were recovered in this dataset further supporting the efficacy of the approach

The molecular hallmarks of primary and secondary vitreoretinal lymphoma

Vitreoretinal lymphoma (VRL) is a rare subtype of diffuse large B-cell lymphoma (DLBCL) considered a variant of primary central nervous system lymphoma (PCNSL). Diagnosis of VRL requires examination of vitreous fluid, but cytologic differentiation from uveitis remains difficult. Due to its rarity and difficulty in obtaining diagnostic material, little is known about the genetic profile of VRL. The aim of our study was to investigate the mutational profile of a large series of primary and secondary VRL. Targeted next generation sequencing using a custom panel containing the most frequent mutations in PCNSL was performed on 34 vitrectomy samples of 31 patients with VRL and negative controls with uveitis. In a subset of cases, genome-wide copy number alterations (CNA) were assessed using the Oncoscan platform. Mutations in MYD88 (74%), PIM1 (71%), CD79B (55%), IGLL5 (52%), TBL1XR1 (48%), ETV6 (45%) and 9p21/CDKN2A deletions (85%) were the most common alterations, with similar frequencies in primary (15), synchronous (3) or secondary (13) VRL. This mutational spectrum is similar to MYD88mut/CD79Bmut (MCD or cluster 5) DLBCL with activation of Toll-like and B-cell receptor pathways and CDKN2A loss, confirming their close relationship. Oncoscan analysis demonstrated a high number of CNAs (mean 18.6/case). Negative controls lacked mutations or CNAs. Using cell free DNA of vitreous fluid supernatant, mutations present in cellular DNA were reliably detected in all examined cases. Mutational analysis is a highly sensitive and specific tool for the diagnosis of VRL and can also be applied successfully to cell free DNA derived from the vitreous.Copyright © 2021 American Society of Hematology

A highly mutagenised barley (cv. Golden Promise) TILLING population coupled with strategies for screening-by-sequencing

Background:We developed and characterised a highly mutagenised TILLING population of the barley (Hordeum vulgare) cultivar Golden Promise. Golden Promise is the 'reference' genotype for barley transformation and a primary objective of using this cultivar was to be able to genetically complement observed mutations directly in order to prove gene function. Importantly, a reference genome assembly of Golden Promise has also recently been developed. As our primary interest was to identify mutations in genes involved in meiosis and recombination, to characterise the population we focused on a set of 46 genes from the literature that are possible meiosis gene candidates. Results:Sequencing 20 plants from the population using whole exome capture revealed that the mutation density in this population is high (one mutation every 154 kb), and consequently even in this small number of plants we identified several interesting mutations. We also recorded some issues with seed availability and germination. We subsequently designed and applied a simple two-dimensional pooling strategy to identify mutations in varying numbers of specific target genes by Illumina short read pooled-amplicon sequencing and subsequent deconvolution. In parallel we assembled a collection of semi-sterile mutants from the population and used a custom exome capture array targeting the 46 candidate meiotic genes to identify potentially causal mutations. Conclusions:We developed a highly mutagenised barley TILLING population in the transformation competent cultivar Golden Promise. We used novel and cost-efficient screening approaches to successfully identify a broad range of potentially deleterious variants that were subsequently validated by Sanger sequencing. These resources combined with a high-quality genome reference sequence opens new possibilities for efficient functional gene validation.Miriam Schreiber, Abdellah Barakate, Nicola Uzrek, Malcolm Macaulay, Adeline Sourdille, Jenny Morris, Pete E. Hedley, Luke Ramsay and Robbie Waug

AGEING OF BINARY Ti-Ni ALLOY AND ITS INFLUENCE ON TRANSFORMATION CHARACTERISTICS

Transformation temperatures of binary alloys from Ti-Ni system are highly sensitive to chemical composition of the alloy. This sensitivity, however, causes rather considerable complications already during process of preparation. Transformation temperatures of bays rich in Ni can be successfully modified. The key to modification of transformation temperatures lies in use of precipitation reaction of quenched over-saturated solution for influencing of composition of TiNi matrix and thus to precise control of transformation temperatures. Principle of this method consists in metastable balance between intermetallic phase TiNi and coherent precipitates Ti3Ni4. Although the precipitate Ti3Ni4 is considered to be metastable in comparison with TiNi3, it is highly stable at temperatures below 600 degrees C. During precipitation reaction Ti3Ni4 is formed and this phenomenon is connected with decrease of Ni content in TiNi matrix, which leads to increased temperatures of phase transformations TR (temperature of formation of R-phase) and Ms (temperature 'martensite start'). It is important that transformation temperature after long-term ageing is independent on chemical composition of the alloy, and it depends only on temperature of ageing as a consequence of equilibrium between these phases. This phenomenon should not occur at ageing at higher temperatures, formation of precipitate Ti3Ni4 should occur only during cooling of the sample from the temperature of ageing. The alloy Ni50.6-Ti (at. %), prepared in high-frequency induction vacuum furnace, was chosen as experimental material. Samples of the alloy were sealed into evacuated quartz glass tube and aged at constant temperature with various durations of dwell. Afterwards transformation characteristics of the samples were determined by DSC method

Processing technologies of Ni-Ti based shape memory alloys

Transformation characteristics and properties of the Ni-Ti based shape memory alloys are in the first place highly dependent on processing technology. It is known that small deviation from the required composition can cause very important change of transformation temperatures. For this reason it is necessary to pay special attention to the metallurgy of these alloys. The current key technologies for processing are in most cases realised in vacuum, and various methods of melting are used (electron-beam melting, arc melting, induction highfrequency melting). Plasma melting is another possibility. Complications during preparation are caused mainly by carbon, nitrogen and oxygen, which form non-metallic inclusions. Carbon is related to the alloys mainly in the course of their preparation in graphite crucibles. Other problems are connected with observation of appropriate conditions for crystallisation and with related minimisation of possible micro- and macro-segregations. Formation of titanium carbide and titanium oxide in Ni-Ti shifts concentration of individual elements and thus leads also to change of the temperature of martensitic transformation. Creation of a low-melting phase Ti2Ni, which causes a distinct susceptibility to hot formation of cracks, is another issue arising during melting of Ni-Ti alloys. The presented article is focused on comparison of individual methods of preparation of the alloys mentioned above, i.e. induction vacuum melting, plasma and electron-beam melting

Measurement of transformation temperatures of Ni-Ti shape memory alloys with using methods continuous change of resistivity as function of temperature and DTA

System Ni-Ti is based on equiatomic compound of nickel and titanium. Ni-Ti based alloys are highly stable and resistant to corrosion. Production of these alloys is very difficult due to high reactivity of titanium. For successful use in practice it is very important to know transformation characteristics of these alloys. Fabrication of alloys on the base of Ni-Ti is realized mostly by vacuum melting processes (electron beam melting, arc melting, induction melting) and plasma melting. During melting of Ni-Ti based alloys, oxygen and carbon have adverse effect. Carbide and oxide from Ti formation lead to changes in concentration of elements and to changes of transformation temperatures. Another problem is formation of the low-melting phase Ti2Ni, which leads to formation of hot cracks. Alloys on the base of Ni-Ti melt usually at the temperature of approx. 1500 K. It is possible to measure transformation temperatures by deformation methods, by DSC method (differential scanning calorimetry) or DTA method (differential thermal analysis), by resistometric methods. Resistometric method enables simple, precise and rapid evaluation of transformation temperatures. In dependence on constitution of alloys, or additional alloying or heat treatment or mechanical treatment It is possible to get different types of dependence of electric resistivity on temperature. This article deals with method of continuous change of resistivity as function of temperature of Ni-Ti alloys, and with influence of deformation and subsequent heat treatment at these temperatures