Study of the sound absorption properties of 3D-printed open-porous ABS material structures

Noise pollution is a negative factor that affects our environment. It is, therefore, necessary to take appropriate measures to minimize it. This article deals with the sound absorption properties of open-porous Acrylonitrile Butadiene Styrene (ABS) material structures that were produced using 3D printing technology. The material's ability to damp sound was evaluated based on the normal incidence sound absorption coefficient and the noise reduction coefficient, which were experimentally measured by the transfer function method using an acoustic impedance tube. The different factors that affect the sound absorption behavior of the studied ABS specimens are presented in this work. In this study, it was discovered that the sound absorption properties of the tested ABS samples are significantly influenced by many factors, namely by the type of 3D-printed, open-porous material structure, the excitation frequency, the sample thickness, and the air gap size behind the sound-absorbing materials inside the acoustic impedance tube. © 2020 by the authors.Ministry of Education, Science, Research, and Sport of the Slovak Republic [KEGA 007TUKE-4/2018, APVV-19-0550]; European Regional Development Fund in the Research Centre of Advanced Mechatronic Systems within the Operational Programme Research, Development, and Education [CZ.02.1.01/0.0/0.0/16_019/0000867

An Estimation of Sufficient Impact Toughness for the Material of a Turbine Shaft

The fracture of a turbine shaft in the case of overloading can exhibit brittle or plastic failure, depending on the material properties, the turbine-shaft geometry and the form of loading. Usually, when the toughness increases, the stiffness of the shaft material is reduced, which can lead to the plastic twist of the shaft. If the fatigue crack appears in the critical region of the shaft then the low impact-toughness value may induce a brittle fracture. During the retrofit of a hydro-power plant a new turbine shaft was produced by quenching-and-tempering technology. Charpy impact-toughness tests showed lower values for the shaft material than those prescribed by the project documentation. Since the turbine shaft for a hydro-power plant is a massive and expensive component, it is necessary to determine a sufficient impact toughness for the material in terms of the geometry and the manner of loading for the turbine shaft. Since only the yield strength and the impact toughness of the material were prescribed, the level 0 of the SINTAP should be applied. The minimum impact toughness values that ensure the ductile fracture of the shaft, cracked circumferentially was also estimated. We also analyzed the variation of the shaft’s carrying capacity resulting from a reduction of the non-cracked ligament in the transversal direction

The analysis of the new conception transportation cableway system based on the tractor equipment

The proportion of cableway skidding is still increasing compared to other technological and transportation ground-based ways of wood skidding which can dramatically change the quality of the environment. Wood skidding can be performed by an unconventional double-drum tractor winch powered by the wheels of the tractor rear axle. The principle of this unique tree transportation cable system with working attachment is protected by the patent. The article is focused on the description of working functions of this transportation system and the analysis of the dynamic strain of the forestry cableway system at different stages of its operating cycle. During the experiment the forces in the towing rope at different weights of tree logs and different speeds of their towing were measured and evaluated

A missense mutation in RPS6KA3 (RSK2) responsible for non-specific mental retardation

Studies the genetic aspects of X-linked mental retardation (XLMR). Subtypes of XLMR; Presence of RPS6KA3 missense mutation; Kinase activity of the R383 mutant.Karine Merienne; Sylvie Jacquot; Solange Pannetier; Maria Zeniou; Agnes Bankier; Jozef Gecz; Jean-louis Mandel; John Mulley; Paolo Sassone-corsi; André Hanaue

Ohtahara syndrome in a family with an ARX protein truncation mutation (c.81C>G/p.Y27X)

Aristaless-related homeobox (ARX) gene mutations cause a diverse spectrum of disorders of the human brain, including lissencephaly, various forms of epilepsy and non-syndromic mental retardation. We have identified a novel mutation, c.81C>G (p.Y27X), within the ARX gene in a family with two affected male cousins. One of the boys was diagnosed with an early infantile epileptic encephalopathy also known as Ohtahara syndrome, whereas his cousin had been diagnosed with West syndrome (WS). Both patients have normal genitalia and neither have lissencephaly. The ARX mutation identified is predicted to yield a severely truncated protein of only 26 amino acids and can be considered as a null mutation. Somewhat surprisingly, however, it does not yield the X-linked lissencephaly with ambiguous genitalia (XLAG) syndrome. We proposed that the ARX mRNA translation re-initiated at the next AUG codon at position c.121–123 (aa 41) and, thus, partly rescued these patients from XLAG. Our in vitro studies show that this N-terminally truncated ARX protein (p.M41_C562) is detected by western immunoblot in lysates from cells transiently transfected with an ARX over-expression construct containing the c.81C>G mutation. Although these findings widen the spectrum of clinical phenotypes because of mutations in the ARX gene, they also emphasize the molecular pathogenetic effect of individual mutations as well as the effect of genetic background resulting in intrafamilial clinical heterogeneity for these mutations

Identification of the gene FMR2, associated with FRAXE mental retardation

Five folate-sensitive fragile sites have been characterized at the molecular level (FRAXA, FRAXE, FRAXF, FRA16A and FRA11B). Three of them (FRAXA, FRAXE and FRA11B) are associated with clinical problems, and two of the genes (FMR1 in FRAXA and CBL2 in FRA11B) have been identified. All of these fragile sites are associated with (CCG)n/(CGG)n triplet expansions which are hypermethylated beyond a critical size. FRAXE is a rare folate sensitive fragile site only recently recognized. Its cytogenetic expression was found to involve the amplification of a (CCG)n repeat adjacent to a CpG island. Normal alleles vary from 6 to 25 copies. Expansions of greater than 200 copies were found in FRAXE expressing males and their FRAXE associated CpG island was fully methylated. An association of FRAXE expression with concurrent methylation of the CpG island and mild non-specific mental handicap in males has been reported by several groups. We now report the cloning and characterization of a gene (FMR2) adjacent to FRAXE. Elements of FMR2 were initially identified from sequences deleted from a developmentally delayed boy. We correlate loss of FMR2 expression with (CCG)n expansion at FRAXE, demonstrating that this is a gene associated with the CpG island adjacent to FRAXE and contributes for FRAXE-associated mild mental retardation.Jozef Gecz, Agi K. Gedeon, Grant R. Sutherland & John C. Mulle