Pressure Environmental Conditions Research Articles

Non-Destruction Evaluation Method for Long-Term Oxidation Behavior of SiC/SiC Composites with Different Preforms in Wet Oxygen.

The implementation of SiC fiber reinforced SiC/SiC composites to aero-engine hot components has attracted wide attention, due to their many excellent properties. Along these lines, in order to predict the oxidation behavior of the material in extreme environments and to explore the effect of different preforms on the oxidative behavior of the composites, four SiC/SiC composites, with different preforms, were oxidized under environmental conditions of pressure of 12 kPa H2O:8 kPa O2:80 kPa Ar, at 1400 °C temperature. Moreover, the morphology and defect distribution of the samples were characterized by carrying out scanning electron microscopy, and micro-computed X-ray tomography measurements. Furthermore, the relation between the micro- and macro-scales was established, so as to be able to predict the oxidation behavior of the composites; not only the quantitative relationship between the mass change rate and the defect volume change rate, but also the combination of micro-computed X-ray images.

Experimental study on spray characteristics of octanol biodiesel and modification of spray tip penetration model

In this paper, the effects of octanol on the spray characteristics of biodiesel are investigated. Four kinds of blends fuel are used to explore the variation of spray tip penetration, spray cone angle, spray area, and spray tip velocity under different injection pressure and environmental pressure conditions. In addition, this article also uses the experimental data to verify the model of Hiroyasu and Arai. The results showed that with the increase in octanol proportion, the spray tip penetration decreased at first and then increased while the spray cone angle and the peak tip velocity increased at first and then decreased. Only the spray area increased gradually. Among various fuels, the blended fuel with 30% octanol has the longest spray tip penetration and the largest spray area, while the blended fuel with 20% octanol has the largest spray cone angle. The prediction data of the Hiroyasu and Arai model is greater than the experimental data. Therefore, this article revises the model by introducing the density term, viscosity term, and the correction factor. Compared with the Hiroyasu and Arai model, the modified spray model is in good agreement with the experimental data and is more suitable for predicting the macroscopic spray characteristics of the blended fuel under high injection pressure.

Exploration of Extreme Environments with Currentand Emerging Robot Systems

The discovery of living organisms under extreme environmental conditions of pressure, temperature, and chemical composition on Earth has opened up the possibility of existence and persistence of life in extreme environment pockets across the solar system. These environments range from the many intriguing moons, to the deep atmospheres of Venus and even the giant gas planets, to the small icy worlds of comets and Kuiper Belt Objects (KBOs). Exploring these environments can ascertain the range of conditions that can support life and can also identify planetary processes that are responsible for generating and sustaining habitable worlds. These environments are also time capsules into early formation of the solar system and will provide vital clues of how our early solar system gave way to the current planets and moons. Over the last few decades, numerous missions started with flyby spacecraft, followed by orbiting satellites and missions with orbiter/lander capabilities. Since then, there have been numerous missions that have utilized rovers of ever-increasing size and complexity, equipped with state-of-the-art laboratories on wheels. Although current generations of rovers achieve mobility through wheels, there are fundamental limitations that prevent these rovers from accessing rugged environments, cliffs, canyons, and caves. These rugged environments are often the first places geologist look to observe stratification from geohistorical processes. There is an important need for new robot mobility solutions, like hopping, rolling, crawling, and walking that can access these rugged environments like cliffs, canyons, and caves. These new generations of rovers have some extraordinary capabilities including being able to grip onto rocks like NASA/JPL LEMUR 2, operate in swarms such as MIT’s microbots, or have high-specific energy fuel cell power supply that is approximately 40-fold higher than conventional lithium ion batteries to Stanford/NASA JPL’s Hedgehog which is able to hop and somersault in low-gravity environments such asteroids. All of these mobility options and supporting technologies have been proposed and developed to explore these hard-to-reach unconventional environments. This article provides a review of the robotic systems developed over the past few decades, in addition to new state-of-the-art concepts that are leading contenders for future missions to explore extreme environments on Earth and off-world.

A Forty-Year Karstic Critical Zone Survey (Baget Catchment, Pyrenees-France): Lithologic and Hydroclimatic Controls on Seasonal and Inter-Annual Variations of Stream Water Chemical Composition, pCO2, and Carbonate Equilibrium

The long-term trends and seasonal patterns of stream water chemical composition in a small remote forested karst catchment, were investigated from 1978 to 2018. Calcium, magnesium, and bicarbonates, the dominant ions, increased over the period together with temperature, while sulfates decreased. Carbonate and sulfate mineral dissolution was the main source of these elements. These trends and the seasonal opposite patterns of discharge vs. temperature, calcite saturation index vs. pCO2 and bicarbonate vs. sulfates, suggested the influence of discharge, of reduced long-range atmospheric pollution, and of increasing air temperature on biological activity and carbonate dissolution. Furthermore, the hydrological regime controlled the seasonal stream water chemical composition and fluxes by: (i) a dilution during the high discharge period, (ii) a change in the contribution rate of the waters draining different lithological areas in the catchment, e.g., the increased sulfates to bicarbonates ratio during summer low flows, with a maximum alkalinity decrease of 24%, and (iii) a “piston” and a “flushing” effects of dissolved elements stored in soils and epikarst with the first autumn heavy rains. Long-term stream water hydrochemical surveys of karst system have proved to be powerful indicators of biogeochemical processes, water sources and pathways under variable natural and anthropogenic environmental pressure conditions.

Features of Muscle Tissue Microstructure of Cattle in Industrial Agglomerations under the Environmental Pressure Conditions

The intensive development of the industrial sector, intensification of the agro-industrial complex, associated with the use of various fertilizers, active use of modern household chemicals lead to the constant increase in xenobiotics in the environment in both rural and urban agglomerations. There are settlements and farms within the industrial areas, therefore, the issue of accumulation of ecotoxicants in the organs and tissues of an animal, as well as the impact on the state of its health, is of particular importance. In the regions with tough environmental situation associated with anthropogenic contamination, xenobiotics of anthropogenic origin can directly or indirectly modify the activity of various body systems. The integral characteristic that reflects adaptive modifications of biota is the morphological and functional status of organs and tissues of an animal, including the state of muscle tissue. An analysis of the regenerative plastic potential of muscle tissue allows finding innovative approaches to assessing the effects of environmental impacts on animals. Up to the present day, the morphological and functional characteristics of muscle tissue in young animals and adult cattle have not been sufficiently studied in the conditions of the tough environmental situation of the Central Federal District of the Russian Federation. The issue of ecological pathologies of organs in productive animals is quite urgent for the territory of the Central Federal District with its developed agro-industrial complex and industry. The study of animals from the agglomeration of the large chemical plant showed that cattle react differently to pollutants. The animals demonstrated changes not only in hematological and biochemical parameters, but also in the morphological and functional status of muscle tissue.

Aging effect on vanadium oxide hybrid nanotubes

Vanadium oxides present a rich magnetic phase diagram depending on the oxidation state of the V ions. In particular the vanadium oxide nanotubes (VOx NTs) present several promising perspectives for different technological applications for which it is essential to know the oxidation state of V ions, as well as to evaluate the stability with the aging time of the tubes. In this work we present a systematic study of the time evolution of the magnetic properties of VOx NTs. For this complete characterization, we used electron spin resonance (ESR) and dc-susceptibility techniques, which were supplemented with TEM microscopy and XANES. We observed that for aging in normal environmental conditions of pressure, temperature and humidity, the V4+ ions oxidize to V5+ . Although the multiwall tubular structure is maintained, this oxidation process produces a marked change in the magnetic properties. We conclude that the aging of the samples affects the V4+ /V5+ relationship in the VOx NTs, which may contribute to explain the significant dispersion of data reported in the bibliography.

FUNCTIONAL ISOTONIC DRINKS BASED ON THE TISSUE FLUID OF RHOPILEMA JELLYFISH

A formulation for the preparation of isotonic drinks based on the tissue fluid of the rhopilema jellyfish (Rhizostomeae) Rhopilema Asamushi is proposed. While jellyfish are made up primarily of water (up to 97% of undried weight), the main chemical factors in maintaining the water-salt balance of jellyfish tissues under environmental pressure conditions are free amino acids (up to 10% of dry weight) and various mineral elements (up to 65% of dry weight). The proportion of the latter significantly exceeds the protein component (up to 20% of dry weight), which distinguishes jellyfish from most species of animals. Prevailing tissue elements are sodium, potassium, calcium, magnesium, iron, zinc, copper, chromium and selenium. Known technologies of jellyfish processing are aimed at obtaining a dense and stable structure of the semi-finished product, while the liquid fraction is removed during processing. In so doing, at least 70% of all water content, as well as mineral elements, free amino acids and water-soluble proteins dissolved in it, are lost. Herein, a method is proposed for separating the liquid fraction of jellyfish tissues from high-molecular impurities using the ultrafiltration method. Due to the presence of low molecular weight soluble components, the solution obtained can serve as the basis for the creation of isotonic drinks containing biologically active substances. As a result, a formulation of isotonic drinks is developed, which brings the value of the osmotic pressure of the obtained product to the limits of the established norms (270-330 mOsm/kg). In this regard, the composition of the formulation includes carbohydrates (glucose and fructose) in the amount of 6,5 g per 100 ml of product. Additionally, a preservative, acidity stabilisers and antioxidants (citric and ascorbic acids) are used, as well as the berry extracts in order to impart attractive organoleptic properties to product. In addition to performing the function of restoring the water-salt balance, these drinks can serve as additional sources of such mineral components as iron, chromium and selenium.

THz Imaging as a Method to Detect Defects of Aeronautical Coatings

Ice adhesion over critical aircraft surfaces is a serious potential hazard that runs the risk of causing accidents. To face this issue, the design and diagnostics of new multifunctional coatings with icephobic and aesthetical properties are demanded. In particular, diagnostic tools, capable of characterizing coating surface finishing and its defects, are needed. In this paper, terahertz (THz) imaging is considered as a high-resolution diagnostic tool useful for contactless surveys providing information on surface defects and material inner structure. Therefore, two composite specimens, one covered by a classical commercial livery coating and the other one by a new multifunctional coating with icephobic properties, are investigated by THz surveys carried out in normal environmental conditions of pressure and temperature. The results, obtained by processing the raw data properly, corroborate that THz imaging allows us to detect variations of the coating thickness, to localize hidden anomalies as well as to characterize surface defects at millimetric scale.

Species and Abundance of Sea Urchins (Diadematidae) on Different Environmental Pressure Conditions

Genetic diversity of sea urchin are very high; there are no two organisms of the same species that are exactly alike. Dense aggregation of sea urchin is responsible for the destruction of marine algae communities on coral reef ecosystem. The purpose of this study is to identify the species and abundance of sea urchins at different environmental conditions, to analyze the influence of water conditions on the abundance of sea urchins and to analyze the role of sea urchin as water quality and abiotic environmental conditions bio-indicators. Data collection procedures carried out in three stage that are: assessment of the status of coral reefs, sea urchins sampling and analysis of data. Data condition of coral reefs is drawn using methods kick frequency. Urchin abundance data retrieval is done by timed swims or snorkeling and species of sea urchins seen through genetic approach, by DNA sequencing. Identify the types of sea urchins in this study conducted with the gene fragment sequences Cytochrome Oxidase subunit I (COI). Stages isolation of DNA-based procedures uses Gsync DNA Extraction Kit from Geneaid. The species that identify in this study is Diadema setosum. Location with high environmental pressures has a low quality of coral reef ecosystems and has a great abundance of sea urchins. This proves that the water environmental conditions greatly affect the abundance/density of sea urchins. In locations with relatively low environmental stress or a sheltered environment the abundance of sea urchins is low.

Roland Winter

Angewandte Chemie International EditionVolume 55, Issue 43 p. 13374-13374 Author ProfileFree Access Roland Winter First published: 04 May 2016 https://doi.org/10.1002/anie.201603733Citations: 2AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract “My favorite place on Earth is a good French brasserie. My not-so-secret passion is astrobiology ...” This and more about Roland Winter can be found on page 13374. The author presented on this page has published 10 articles in Angewandte Chemie in the last 10 years, including: “Condensation Agents Determine the Temperature–Pressure Stability of F-Actin Bundles”: M. Gao, M. Berghaus, J. von der Ecken, S. Raunser, R. Winter, Angew. Chem. Int. Ed. 2015, 54, 11088; Angew. Chem. 2015, 127, 11240. Roland Winter Date of birth: October 22, 1954 Position: Professor of Physical Chemistry, TU Dortmund University E-mail: roland.winter@tu-dortmund.de Homepage: http://www.ccb.tu-dortmund.de/fb03/de Education: 1979 Diploma in Chemistry, Technische Universität Karlsruhe 1982 PhD supervised by Ulrich Schindewolf, Technische Universität Karlsruhe 1983–1986 Working at the University of Marburg 1987–1988 Postdoctoral work with Jiri Jonas, University of Illinois at Urbana-Champaign 1991 Habilitation (mentor: Friedrich Hensel), University of Marburg Awards: 1992 Dozentenpreis, Fonds der Chemischen Industrie Current research interests: Biophysical Chemistry: membrane and protein biophysics, signal transduction, amyloidogenesis, solvation, high-pressure biophysics Hobbies: Literature, history of art, wine tasting My favorite place on Earth is a good French brasserie. My not-so-secret passion is astrobiology. If I could have dinner with three famous scientists from history, they would be Linus Pauling, Erwin Schrödinger, and Ludwig Boltzmann. And I would ask them how they would deal with unfavorable referee reports. I chose chemistry as a career because I had highly motivating teachers in chemistry and physics. The most exciting thing about my research is being surrounded by highly motivated students. The best advice I have ever been given is to search for a niche in science that has not been explored yet. I can never resist to accept an invitation from good friends. I celebrate success by clinking glasses at a great meal with friends. My favorite authors include James Joyce, Kazuo Ishiguro, Haruki Murakami, and Robert Harris. My top three films of all time are Monsieur Hulot, Star Wars, Lord of the Rings. What I look for first in a publication is if our work has been cited. My favorite piece of research is to explore the limits of life. When I'm frustrated, I grab a good book. My 5 top papers: References 1“Pressure Modulation of the Enzymatic Activity of Phospholipase A2, A Putative Membrane-Associated Pressure Sensor”: S. Suladze, S. Cinar, B. Sperlich, R. Winter, J. Am. Chem. Soc. 2015, 137, 12588. (Exploration of how pressure stress may be sensed by biological membranes.) 2“Prebiotic Cell Membranes that Survive Extreme Environmental Pressure Conditions”: S. Kapoor, M. Berghaus, S. Suladze, D. Prumbaum, S. Grobelny, P. Degen, S. Raunser, R. Winter, Angew. Chem. Int. Ed. 2014, 53, 8397; Angew. Chem. 2014, 126, 8537. (Explains why prebiotic lipid containers are stable at high pressure in the deep sea.) 3“Revealing conformational substates of lipidated N-Ras protein by pressure modulation”: S. Kapoor, G. Triola, I. R. Vetter, M. Erlkamp, H. Waldmann, R. Winter, Proc. Natl. Acad. Sci. USA 2012, 109, 460. (Lipidated signaling proteins are able to populate different conformational substates at membrane interfaces.) 4“Cross-Amyloid Interaction of Aβ and IAPP at Lipid Membranes”: J. Seeliger, F. Evers, C. Jeworrek, S. Kapoor, K. Weise, E. Andreetto, M. Tolan, A. Kapurniotu, R. Winter, Angew. Chem. Int. Ed. 2012, 51, 679; Angew. Chem. 2012, 124, 703. (Amyloidogenic peptides may interfere with each other, thereby affecting their membrane-partitioning behavior and cytotoxicity.) 5“Exploring the Piezophilic Behavior of Natural Cosolvent Mixtures”: M. A. Schroer, Y. Zhai, D. C. F. Wieland, C. J. Sahle, J. Nase, M. Paulus, M. Tolan, R. Winter, Angew. Chem. Int. Ed. 2011, 50, 11413; Angew. Chem. 2011, 123, 11615. (Naturally evolved compatible osmolytes are able to alleviate deleterious environmental stresses such as high hydrostatic pressure.) Citing Literature Volume55, Issue43October 17, 2016Pages 13374-13374 ReferencesRelatedInformation

Gas chromatography for in situ analysis of a cometary nucleus V. Study of capillary columns’ robustness submitted to long-term reduced environmental pressure conditions

With the European Space Agency's Rosetta space mission to comet 67P/Churyumov-Gerasimenko, a gas chromatograph, part of the COmetary Sampling And Composition (COSAC) experiment, travelled for about 10 years in the interplanetary medium before operating at the surface of the cometary nucleus in November 2014. During its journey in space, the instrument was exposed to the constraining conditions of the interplanetary medium, including reduced environmental pressures. In order to estimate the potential influence of this severe condition on the chromatographic capillary columns, their stationary phase and the subsequent separation capability, a set of flight spare columns were kept under reduced environmental pressure in the laboratory for the same duration as the probe sent to the comet. The columns’ analytical performances were evaluated recently and compared to the original ones obtained just before the launch of the Rosetta probe. The results presented here show that the chromatographic performances of the spare chromatographic columns were not altered in time. From this result, it can be expected that the flight instrument will perform nominally for the analysis of the first cometary nucleus sample to be collected ever, and that the preparation of the interpretation of the data to be taken at the cometary surface nucleus can be done through calibration of these spare columns, and other spare components of the instrument.

Prebiotic Cell Membranes that Survive Extreme Environmental Pressure Conditions

AbstractAttractive candidates for compartmentalizing prebiotic cells are membranes comprised of single‐chain fatty acids. It is generally believed that life may have originated in the depth of the protoocean, that is, under high hydrostatic pressure conditions, but the structure and physical–chemical properties of prebiotic membranes under such conditions have not yet been explored. We report the temperature‐ and pressure‐dependent properties of membranes composed of prebiotically highly‐plausible lipids and demonstrate that prebiotic membranes could not only withstand extreme temperatures, but also serve as robust models of protocells operating in extreme pressure environments. We show that pressure not only increases the stability of vesicular systems but also limits their flexibility and permeability to solutes, while still keeping the membrane in an overall fluid‐like and thus functional state.

Prebiotic cell membranes that survive extreme environmental pressure conditions.

Attractive candidates for compartmentalizing prebiotic cells are membranes comprised of single-chain fatty acids. It is generally believed that life may have originated in the depth of the protoocean, that is, under high hydrostatic pressure conditions, but the structure and physical-chemical properties of prebiotic membranes under such conditions have not yet been explored. We report the temperature- and pressure-dependent properties of membranes composed of prebiotically highly-plausible lipids and demonstrate that prebiotic membranes could not only withstand extreme temperatures, but also serve as robust models of protocells operating in extreme pressure environments. We show that pressure not only increases the stability of vesicular systems but also limits their flexibility and permeability to solutes, while still keeping the membrane in an overall fluid-like and thus functional state.

Formation of Ag‐Cu nanoparticles in SiO2 films by sol‐gel process and their effect on the film properties

AbstractSol‐gel thin films and microcrystalline powders of SiO2 doped with Ag and Cu were obtained under environmental conditions of pressure and temperature. The precursor material was a mixture of water, tetraethyl‐orthosilicate, ethanol and aqueous solutions of Ag and Cu salts, the components were taken in ratios known to provide SiO2 matrix material with good structure. The annealing was performed in oxidizing and reducing atmosphere, the temperature varied in the range of 100–800 °C. Formation of metal particles of 100 nm order of magnitude was confirmed by X‐ray, optical and SEM analysis. In presence of metal particles, the SiO2 matrix was crystallized in α‐cristobalite at annealing temperature as low as 500 °C, and in quartz form at 800 °C. A simple model treating the metal‐induced low‐temperature crystallization is presented. The material obtained is promising for the use as optical filter, gas sensing element and antibacterial agent. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electroslag-melted molybdenum

The preparation of molybdenum ingots by electroslag melting is discussed, ingot characteristics are described, and results of mechanical testing of wrought products are compared with those from similar material prepared from arc-cast molybdenum. Thermochemical considerations limit the choice of slag materials to a few high-temperature oxides; of these, yttrium oxide was found to be best suited for use in molybdenum melting. The use of additives to the slag was found necessary to minimize the occurrence of excessive oxide films at ingot grain boundaries. Changes in ingot surface and structure were found to be responsive to changes in such melting variables as power input, electrode spacing, electrode polarity, and environmental pressure conditions. Pressure conditions, electrode polarity, and the slag additives carbon and yttrium, were found to influence the oxygen level and occurrence of extraneous oxide phases in the ingots. Excellent surface conditions are normally associated with the electroslag ingots; as a direct result, much less waste in conditioning ingots for fabrication was encountered than is normal for arc-cast ingots. Additional material economy results from the unusually low temperature at which the electroslag ingots can be fabricated. Sheet fabricated from the electroslag-melted ingots appears to have mechanical properties superior to those of sheet prepared from similar arc-cast ingots.