Structural phase transformations in welding high-alloyed titanium alloy

This article investigates the change in the phase composition and structural state during the thermal cycle of welding a high-alloyed titanium alloy. It is shown that structural-phase transformations in the welded joint occurring under the influence of the thermal and deformation cycle of welding lead to the formation of metastable phases, and its subsequent decomposition can lead to ductility losses. To bring the metal of the welded joint to an equilibrium state, stabilizing annealing is required.

Generation of Microclimates From the Differential Decomposition of Textiles in North Central Florida

The analysis of textiles as trace evidence is an important area of focus in the field of forensic science, because enhanced understanding of the decomposition of textiles may point to more accurate methods for estimating the post mortem interval (PMI) of remains found in association with these materials. This research is especially crucial in areas with unique climates, like the state of Florida. This study examines the generation of microclimates from the differential decomposition of various textile types. This study hypothesized that the decomposition of textiles will generate microclimates with soil properties that differ from those of the surrounding environment, and that different types of textiles will create different microclimates as they decompose. Samples of cotton, UV-proofed cotton, polyester, cotton-polyester blended fabric, ripstop, and wool were buried at four sites on a property in North Central Florida for thirteen weeks, with measures of soil temperature, pH, and moisture level, and weather data collected weekly. Following burial, decomposition of each textile type was scored. Data collected were analyzed in R statistical software. Analysis indicated that the level of degradation differed by textile type but not by site. Textile presence, type of textile, and subsequent decomposition significantly impacted soil pH and moisture at all sites, but did not have a significant effect on soil temperature. The results of this study demonstrate that the decomposition of textiles can create diverse and unique microclimates in the soil environment. When found in association with human remains, presence and type of textile should be considered when estimating decomposition rates and the postmortem interval.

Atomic Scale Mechanisms Controlling the Oxidation of Polyethylene: A First Principles Study

Understanding the degradation mechanisms of aliphatic polymers by thermal oxidation and radio-oxidation is very important in order to assess their lifetime in a variety of industrial applications. We focus here on polyethylene as a prototypical aliphatic polymer. Kinetic models describing the time evolution of the concentration of chain defects and radicals species in the material identify a relevant step in the formation and subsequent decomposition of transient hydroperoxides species, finally leading to carbonyl defects, in particular ketones. In this paper, we first summarize the most relevant mechanistic paths proposed in the literature for hydroperoxide formation and decomposition and, second, revisit them using first principles calculations based on Density Functional Theory (DFT). Our results partially confirm commonly accepted reaction energies, but also propose alternative, more favourable, reaction paths. We highlight the influence of the environment—crystalline or not—on the outcome of some of the studied chemical reactions. A remarkable result of our calculations is that hydroxyl radicals play an important role in the decomposition of hydroperoxides. Based on our findings, it should be possible to improve the set of equations and parameters used in current kinetic simulations of polyethylene radio-oxidation.

Investigation of Temperature Deformations and Burning of Models from Polymers

The usage of 3D printing technology SLA and DLP is promising for obtaining casting models. The article presents the results of a study of temperature deformations, developing during the burning of models from polymers “Fun to Do Castable Blend”, “Oh-All! Red” and “Orange Fluor”. In the performance of the experiments, photopolymer models were exposed to an impact of isothermal at temperatures from 50 to 330 °C, and their linear dimensions measured; changes developing on their surface were noted. It is shown that, with an increase of the isothermal holding temperature, the models expand first and narrow later. It has been linked to temperature expansion and subsequent decomposition of the photopolymer. It is shown that the casting molds ,obtained with the usied thin-walled hollow casting models from these photopolymers, are destroyed at the stage of their burning.

Soil organic carbon storage in a mountain permafrost area of Central Asia (High Altai, Russia)

The thawing and subsequent decomposition of large stocks of soil organic carbon (SOC) currently stored in the northern circumpolar permafrost region are projected to result in a ‘positive’ feedback on global warming. The magnitude of this feedback can only be assessed with improved knowledge about the total size and geographic distribution of the permafrost SOC pool. This study investigates SOC storage in an under-sampled mountain permafrost area in the Russian High Altai. SOC stocks from 39 soil pits are upscaled using a GIS-based land cover classification. We found that the top 100 cm of soils in Aktru Valley and the adjacent Kuray Basin only holds on average 2.6 ± 0.6 kg C m−2 (95% confidence interval), of which only c. 1% is stored in permafrost. Global warming will result in an upward shift of alpine life zones, with new plant cover and soil development at higher elevations. As a result, this type of mountain permafrost area might act as a net C sink in the future, representing a ‘negative’ feedback on global warming.

Pseudoleucite syenites at Loch Borralan, Scotland: Petrology and a genetic model

ABSTRACT The alkaline Loch Borralan intrusion (Assynt Region, NW Highlands of Scotland) consists of a composite arrangement of several ultramafic to felsic plutonic rock bodies which were emplaced around 430 Ma into the Moine Thrust Zone during the Caledonian Orogeny. Some of the Loch Borralan rocks are ultrapotassic and contain pseudoleucite, i.e., a pseudomorph of alkali feldspar and nepheline after leucite. In total, 25 samples have been investigated, representing garnet-bearing pseudoleucite syenites and accompanying rock types such as nepheline-garnet-bearing syenites, alkali feldspar syenites, an amphibole syenite, a biotite-clinopyroxene syenite, and calcite-bearing glimmerites. Pseudoleucite is always associated with garnet, biotite, orthoclase, and minor clinopyroxene and titanite. Mineral chemical data indicate rather primitive magma compositions with no major differences between the various investigated main rock units. The abundant occurrence of up to 2 cm large, mostly euhedral pseudoleucite crystals and petrological phase considerations suggest that magmatic leucite physically separated from its host magma as a flotation cumulate. Based on our data and a comparison with previous field-based and experimental work, K-rich basanitic to tephriphonolitic melts that originated from a K-enriched mantle source may be parental to these rocks. The high liquidus temperatures at low pressures (e.g., ∼1100 °C at 1 bar PH2O) required to crystallize leucite could have resulted from the ascent of successive melt batches in a composite intrusion. Later melt batches would increase the temperature in earlier, already partially cooled batches, causing an increase in temperature and a decrease in pressure during ascent. The subsequent decomposition of leucite to pseudoleucite is interpreted to result from either dry breakdown or autometasomatism, i.e., involvement of late-magmatic fluids.

Application of the approach of readiness levels for various subject areas in lean R&D

The further development of the TPRL methodology as a tool for the commercialization of innovations is proposed. Descriptions of readiness metrics for lean R&D are presented. The expediency of subsequent decomposition of the readiness level criteria into the subject level and project levels for various technological / subject areas / complex systems is shown. Description of the initial scientific readiness levels SciRL are proposed for use in research dedicated to generating knowledge.

Analysis of Adsorption and Decomposition of Odour and Tar Components in Tobacco Smoke on Non-Woven Fabric-Supported Photocatalysts

The release of substantial amounts of toxicologically significant, irritant, and malodourous compounds during the complete combustion of tobacco can generate an unpleasant environment, especially indoors. Herein, we developed non-woven fabric-supported UV- and visible-light-responsive photocatalysts capable of adsorbing and decomposing the odour and tar components of tobacco smoke under irradiation with UV or visible light. The processes of odour component adsorption and subsequent decomposition under irradiation were evaluated in terms of colour changes in the catalytic system and by gas chromatography–mass spectrometry. By considering three different photocatalysts, namely TiO2, Fe(III)-grafted TiO2, and Cu(II)-grafted WO3, we assessed the magnitude of odour and tar component adsorption on the fabric fibres, as well as the decomposition of these species after specific visible light or UV irradiation periods. Considering the expansion of our technology for practical applications, the best results among the three tested materials were obtained for non-woven fabric-supported Fe/TiO2. We believe that our technology can be implemented in the design of interior decoration materials for creating a comfortable environment.

Biological Corrosion of Concrete

The article considers the results of studies to determine the causes, mechanisms and features of biological corrosion of cement concrete. It has been found that the intensive growth of microorganisms on the surface and in the pores of concrete leads to the formation of corrosive biogenic substances and, as a result, the reduction of alkalinity of cement stone with its subsequent decomposition. The influence of certain types of biogenic substances on the components of cement concrete (biogenic organic acids, biogenic carbon dioxide, biogenic nitric acid, biogenic hydrogen sulphide and sulfuric acid) is considered. Methods for increasing the biological resistance of concrete are described, such as: adding additives that can form buffer systems capable of reducing the impact on cement concretes of acids produced by microorganisms; treating the surface of composites with substances capable of repelling microorganisms and environments necessary for their vital activity; use of active media capable of forming dense and inert layers on the surface of the material. Despite the available methods of increasing the biological resistance of cement concrete, it is not possible to fully guarantee their safety from biocorrosion, at least because microorganisms can adapt to the environment and suspend the effect of protection. In this regard, the work attempts to assess and predict the biological resistance of the material.

Study of the temperature effect on the morphology and structure of ZnS nanoparticles synthesized by hydrothermal method

The control over the materials structure is crucial for the modulation of its properties, in order to achieve this control is important to know the formation mechanism of the material as function of parameters used. For this purpose, the effect of temperature (120, 140, 160 and 180 °C) on the hydrothermal synthesis of zinc sulphide is evaluated and a proposal of the sequence of reactions formation of zinc sulphur is presented. ZnS nanostructures with blend-phase were obtained, the temperature increment induces the growth of the nanostructure ranged between .62 and 12.72 nm, furthermore, increase the crystallinity of the ZnS nanostructures. The proposed reactions suggest the formation of a complex of thioacetamide with the Zn+2 and its subsequent decomposition into ZnS.