Use Of Inert Gas Research Articles

Mine Fires, Experiences in Extinguishing Large Underground Mine Fires

Mine fires are common the underground exploitation of mineral raw materials. With the development of mining science and practice, the methods of extinguishing mine fires using new methods and materials were also developed. Today, in mining practice, direct fire extinguishing with water or fire extinguishers, isolation of oxidation zones with insulating walls, installation of torket concrete on the walls of the pit room or use of special foams are most often used. Methods based on ventilation methods or the use of inert gases can also be encountered. All these methods are used to extinguish local oxidation processes, fires are localized in a part of the pit, ventilation department or goafs. This paper presents methods of extinguishing a mine fire where the fire zone covered a larger area and it was not possible to localize it in one part of the underground mine, the pit is completely closed and isolated until the oxidation process subsides due to lack of oxygen. At the time of the complete closure and isolation of the pit, several gas detectors remained in operation in the pit, through which the change in the composition of the pit air could be monitored during the still active pit fire. At the same time, samples of the pit atmosphere behind the isolation walls were regularly taken, their analysis was performed and they were compared with the data obtained using active gas detectors. The key question was when to reopen the pit, conduct an inspection and try to reactivate the pit operations. Although it is an underground brown coal mine, some experiences and knowledge can be applied and used in underground mines of other mineral resources threatened by pit fires. Experiences can also be applied in case of fire, where it is possible to control the fire zone only through insulating walls. It was established that changes in the activity of the pit fire were manifested both on the insulation walls and on the active gas detectors.

Monolithic Use of Inert Gas for Highly Transparent and Conductive Indium Tin Oxide Thin Films.

Due to its excellent electrical conductivity, high transparency in the visible spectrum, and exceptional chemical stability, indium tin oxide (ITO) has become a crucial material in the fields of optoelectronics and nanotechnology. This article provides a thorough analysis of growing ITO thin films with various thicknesses to study the impact of thickness on their electrical, optical, and physical properties for solar-cell applications. ITO was prepared through radio frequency (RF) magnetron sputtering using argon gas with no alteration in temperature or changes in substrate heating, followed with annealing in a tube furnace under inert conditions. An investigation of the influence of thickness on the optical, electrical, and physical properties of the films was conducted. We found that the best thickness for ITO thin films was 100 nm in terms of optical, electrical, and physical properties. To gain full comprehension of the impact on electrical properties, the different samples were characterized using a four-point probe and, interestingly, we found a high conductivity in the range of 1.8-2 × 106 S/m, good resistivity that did not exceed 1-2 × 10-6 Ωm, and a sheet resistance lower than 16 Ω sq-1. The transparency values found using a spectrophotometer reached values beyond 85%, which indicates the high purity of the thin films. Atomic force microscopy indicated a smooth morphology with low roughness values for the films, indicating an adequate transitioning of the charges on the surface. Scanning electron microscopy was used to study the actual thicknesses and the morphology, through which we found no cracks or fractures, which implied excellent deposition and annealing. The X-ray diffraction microscopy results showed a high purity of the crystals, as the peaks (222), (400), (440), and (622) of the crystallographic plane reflections were dominant, which confirmed the existence of the faced-center cubic lattice of ITO. This work allowed us to design a method for producing excellent ITO thin films for solar-cell applications.

Spark plasma sintering of 13Ni-400 maraging steel: Enhancement of mechanical properties through surface modification

The present work aimed to reduce the amount of gas-atomized spherical powder, cost reduction, and reduction in the use of inert gas (N2, Ar) used during the selective laser melting process but to have similar properties and functionalities through the spark plasma sintering (SPS) process. In this work, 13Ni-400 maraging steel disks were fabricated using Spark Plasma Sintering (SPS) using optimized process parameters. The SPS samples are then subjected to surface melting and layered deposition processes. A detailed microstructural characterization and mechanical testing (hardness and compression properties) were carried out on these samples. The results indicated that the surface melted specimen exhibited the best combination of mechanical properties and microstructure, with a highly refined and uniform microstructure. This was attributed to the unique processing conditions employed during surface melting allowing the material to rapidly solidify. The surface melted samples show the highest yield strength among the three conditions (SPS, SPS + surface melting, and SPS + layer deposition). However, both the surface melting and layer deposited samples have similar ultimate compressive strength. Overall, the study offers a promising approach for producing defect-free parts with maximum densification and improved mechanical properties for newly developed 13Ni-400 maraging steel.

Novel one-stage process for manufacturing 1,3-butadiene from ethanol

This paper proposes a novel process for manufacturing 1,3-butadiene from renewable bioethanol, and re-evaluates two alternative processes: one-stage (Lebedev) and two-stages (Ostromislensky). The work presents an innovative design of the one-stage process employing Hf(IV)/Zn(II) catalyst and a consistent comparison of the above processes. The analysis is based on detailed reaction kinetics and systematic process synthesis. This work is distinct from previous studies by its use of inert gas in the reactor design in order to reproduce laboratory conditions, namely low ethanol partial pressure. Methane is proposed instead of the less-efficient nitrogen. The innovative reaction system involves adiabatic radial-flow reactors hosting catalyst particles of 2 mm that ensure high efficiency and reduced pressure drop. Cryogenic distillation and DMF absorption are assessed as alternatives for butadiene separation. Original methods are developed for removing by-products and impurities. Hence, the proposed flowsheet is generic for one-stage processes. Economic analysis reveals that the compression of inert-gas rich mixtures contributes substantially to the increase in capital and operation costs. Therefore, with today’s available catalysts, the two-stage process appears more efficient than the one-stage process. To reduce this gap, a performant one-stage catalyst should show high butadiene selectivity by employing a small or no amount of inert gas.

Some Beneficial Effects of Inert Gases on Blood Oxidative Metabolism: In Vivo Study.

The aim of the study was to assess the effect of external use of inert gases (helium and argon) on the state of free radical processes in vivo. The experiment was performed on 30 male Wistar stock rats (age-3 months, weight-200-220 g.), randomly distributed into 3 equal groups. The first group of animals was intact (n = 10). The animals of the second and third groups were treated with argon and helium streams, respectively. Our research has allowed us to establish that the studied inert gases have a modulating effect on the state of oxidative metabolism of rat blood, and the nature of this effect is directly determined by the type of gas. The results of this study allowed us to establish the potential antioxidant effect of the helium stream, mainly realized due to the activation of the catalytic properties of the enzymatic link of the antioxidant system of rat blood plasma. At the same time, the revealed features of shifts in oxidative metabolism during treatment with argon flow include not only stimulation of the antioxidant system but also the pronounced induction of free radical oxidation. Thus, the conducted studies made it possible to verify the specificity of the response of the oxidative metabolism of blood plasma to the use of inert gases, depending on their type.

Safety of parapulmonal application of xenon in the experiment

Pain syndrome is the most common reason for patients to seek medical care, the importance of which is steadily increasing in the structure of the total incidence. To optimize costs and ensure high-quality treatment of patients with chronic pain syndrome it is necessary to study existing drugs and methods and introduce new ones. Based on theoretical data on the use of inert gases in medicine, a hypothesis was put forward that xenon could have a pronounced analgesic effect when administered subcutaneously. This study is aimed at confirming the safety of xenon in parapulmonary administration to rats.

Explosion characteristics of coal dusts in O2/N2 ambience: A novel method to determine limiting oxygen concentration

The explosion characteristics of anthracite and bituminous coals in O2/N2 ambience were experimentally studied via a 20-L spherical explosion chamber with various ignition energies of 2, 5 and 10 kJ. A novel method based on combustion duration time was proposed for the first time, with an emphasis on the determination of the limiting oxygen concentration (LOC). The values of LOC determined by the alternative method were almost consistent with those obtained by using the standardized overpressure method, where the LOCs were above 21.6%, 19.8%, and 13.2% for anthracite coal and 11.4%, 9.6%, and 9.0% for bituminous coal when the ignition energy is 2, 5, and 10 kJ, respectively. But the newly proposed method was found to be much less affected by the ignition energy compared with the standardized overpressure method, taking combustion duration time as an explosion criterion thus had a higher efficiency and required fewer experiments. The results also showed that as oxygen concentration decreases from 21.6% to 14.4%, the maximum explosion pressure decreases from 0.4334 MPa to 0.1034 MPa for anthracite coal and from 0.5664 MPa to 0.3981 MPa for bituminous coal, respectively. Moreover, the effect of ignition energy varied with varying volatile matter content and ignition mechanism of coal dusts. The higher the volatile content, the less sensitive it is to the ignition energy. The newly proposed method will provide a reference for the new standard development, hazard analysis, explosion prevention and suppression by involving the use of inert gases of combustible powder industries.

Selection of an Inert Gas System for the Transportation of Direct Reduced Iron

Direct reduced iron (DRI) can create significant risks such as ignition, explosion, and fire because of the oxidation reaction in case when DRI undergoes spontaneously heating and comes in contact with oxygen or water. For this reason, the transportation of DRI is classified as a dangerous task of which the inert process should be done in the ship’s holds. Many studies have been conducted on the production and production stages of DRI and other areas of use of inert gas, but no studies have been conducted on the safe transportation of this cargo by ships. This study analyzes the criteria and alternatives for selecting the inert gas system for the benefits of investors and shipowners in the shipping industry. The intuitionistic fuzzy TOPSIS (IF-TOPSIS) method is implemented to conduct the decision-making process. As a result of this study, preferences for candidate inert gas systems are modelled. Port facility nitrogen generator is selected as the most suitable inert gas system among alternative inert gas systems based on predetermined criteria.

Low Carbon Sinter Making: Use of Inert Gas to Improve Sinter RDI

Low Carbon Sinter Making: Use of Inert Gas to Improve Sinter RDI

Synthesis of Carbon Nano Rods from Plastic Waste (PP) Using MgO AS A Catalyst

In this research, CNRs have been synthesized using pyrolysis of plastic waste(pp) at 1000 ° C for one hour in a closed reactor made from stainless steel, using magnesium oxide (MgO) as a catalyst. The resultant carbon nano rods were purified and characterized using energy dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD). The surface characteristics of carbon rods were observed with the Field emission scanning electron microscopy (FESEM). The carbon was evenly spread and had the highest concentration from SEM-EDX characterization. The results of XRD and FESEM have shown that carbon Nano rods (CNRs) were present in Nano figures, synthesized at 1000 ° C and with pyrolysis temperature 400° C. One of the advantages of this method is that using one reactor for a short time and without any use of inert gas as opposed to previous researches which used two reactors.

Copper-Mediated Deprotection of Thiazolidine and Selenazolidine Derivatives Applied to Native Chemical Ligation.

Cupric sulfate efficiently opens thiazolidine and selenazolidine rings, producing a protected N-terminal cysteine or selenocysteine derivative without the use of inert gas or solvent. This is a clear advantage over methods that use water-soluble palladium salts, which fail to react with the selenazolidine ring. This copper-mediated reaction proceeds with monovalent or divalent copper ions, and disulfide bond formation followed by ring-opening promotes the process. This copper-mediated reaction, which is compatible with the standard native chemical ligation conditions, was applied to the synthesis of the 77-mer CXCL14 protein.

The effect of an inhibitor on the torrefaction of pellets inside a quiescent layer of bentonite clay

Biomass fuel pellets are an important product for the energy sector. The disadvantages of biomass as a sustainable alternative fuel when compared with coal and other fossil fuels are mainly attributed to its low energy density. To improve the biomass properties the torrefaction process can be used. This study aims at investigating the new technique of pellets torrefaction inside a quiescent layer of bentonite under the atmospheric conditions. This process of torrefaction is carried out without the use of inert gas that makes it attractive from the economic and ecological points of view. The main purpose of bentonite in this technique is to limit oxygen access to the biomass from the environment since oxygen excess leads to the decrease in the energy yield. It is also proposed to use the salts of alkali metals as an inhibitor of the oxidation reactions. In this work, the effect of sodium hydrocarbonate addition on the mass and energy yields of biomass is analyzed at varying torrefaction temperature, duration and height of the mineral layer. Pyrolytic behavior of torrefied biomass is analyzed with the use of thermogravimetry and differential scanning calorimetry measurements. It is established that the mass and energy yields occur to be higher in case of torrefaction in the bentonite-soda blend than in case of torrefaction in pure bentonit. Furthermore, the use of bentonite-soda blend favors the decrease in enhancement factor of HHV. It is shown that energyyield≈1.15⋅massyield.

Experimental study of the permeability and poromechanical properties of thermally damaged granite

Two objectives are targeted with this experimental study carried out on a granite heated up to 600 °C. The first one is to evaluate the coupled effects, on permeability and poromechanical properties, of the thermal treatment followed by three kinds of cooling (slow process in the oven or in the air and quick process in cold water). The second objective was to analyse the efficiency of the experimental procedure carried out to make the measurements, i.e. the use of inert gas or water to control the pore pressure. The use of gas clearly leads to more accurate observations than with water. It is especially true on the effects of confining pressure on permeability. A micro-cracking process goes along with the heating and is amplified by the thermal shock. This leads to high increase in permeability, which becomes more and more sensitive to the confining pressure. This is confirmed by the decrease in the drained bulk modulus K b, in the expansion coefficient H and the increase in the Biot’s coefficient.

Use of Inert Gases for the Preservation of Nuclear Blood Cells

Abstract The subject of the study was the stability of human white blood cell membranes subject to noble gases (xenon ad krypton, 0.6 mPa) clathrate cryoanabiosis (‒80°C). A unique portable stainless steel low pressure container with a compartment for flexible plastic container was designed to ensure that the cells are saturated with gases. The samples were warmed after 1 and 30 days in a water bath (+38°C) for 35-50 sec, while the container was being tilted (2-3 times per second), until the temperature of the biological object reached +3±1°C. It was demonstrated that after 30 days of clathrate anabiosis (-80°C) over 95% (of the original number) of leukocytes remain viable, and cell membranes of 54.5±3.4% of them is resistant to trypan blue; granulocyte survival rate is 73.5±2.7%, original lipid peroxidation rate and antioxidant activity are retained. Biological object cryopreservation in noble gases environment is a promising trend in biology and medicine.

Nitrogen inhalation suicide pacts

Suicide pacts usually result in simultaneous deaths by mutual arrangement. While nitrogen and helium gas inhalation are being increasingly used in solitary suicide attempts, for some reason they have been rarely utilised in suicide pacts. A search of autopsy files at Forensic Science SA over a 15-year period (2003-2017) was undertaken to determine how often this method of joint suicide occurs. Only two cases were found. Case 1 comprised a 64-year-old husband and wife (who had a history of multiple sclerosis). They were found deceased in a vehicle with two empty cylinders of nitrogen gas. Case 2 comprised an 87-year-old man (who had a history of ischaemic heart disease) and his 81-year-old wife who were found deceased with plastic bags over their heads, with plastic tubes connecting the bags to opened cylinders of nitrogen. The deaths in all cases were due to nitrogen-induced asphyxiation, in the latter instance augmenting plastic-bag asphyxia. Although suicide pacts have previously usually involved carbon-monoxide toxicity or drug overdose, it is possible that dissemination of information on the use of inert gases in individual suicide attempts may alter the methods used in future.

Oxidative torrefaction of pine pellets in the quiescent layer of mineral filler

Torrefaction is a mild pyrolysis, which is used for biomass pretreatment aimed to increase the heating value and hydrophobicity. Nowadays there are a lot of various torrefaction techniques. The heating of the wood pellets or briquettes inside the layer of mineral particles under atmospheric conditions can represent one of the prospective torrefaction techniques. Significant diffusion resistance of the mineral layer can favor substantial reduction in the oxygen flux to the biomass from the environment. Due to this one can carry out torrefaction without the use of inert gas. The paper analyzes experimentally the torrefaction of pine pellets inside the layer of bentonite clay or microcalcite. It is established experimentally that the height of mineral layer does not affect significantly on the mass yield at 230°C. However, under the conditions of severe torrefaction (290°C) the increase in mass yield with height of mineral layer is observed. The calorific properties of torrefied biomass are estimated on the basis of elemental analysis. It is shown that the value of energy yield increases together with the mass yield.

Oxidative torrefaction of briquetted birch shavings in the bentonite

Oxidative torrefaction of briquetted birch shavings inside the quiescent layer of bentonite clay was investigated in a muffle furnace. In the considered process the briquettes are buried under the layer of bentonite clay and the reactor is heated at atmospheric conditions without the use of inert gas. The main role of the bentonite clay is to limit the oxygen access to the torrified biomass from the environment. The paper considers the effects of briquette thickness, bentonite layer height, temperature and torrefaction duration on the mass yield and energy yield of the biomass. It is shown that to increase the enhancement factor of HHV of the biomass it is necessary to reduce both the height of bentonite clay and the briquette thickness. As well the torrefaction temperature and duration should be increased. It is also established that the height of bentonite layer affects negligibly on the energy yield.

Faults as Windows to Monitor Gas Seepage: Application to CO2 Sequestration and CO2-EOR

Monitoring of potential gas seepage for CO2 sequestration and CO2-EOR (Enhanced Oil Recovery) in geologic storage will involve geophysical and geochemical measurements of parameters at depth and at, or near the surface. The appropriate methods for MVA (Monitoring, Verification, Accounting) are needed for both cost and technical effectiveness. This work provides an overview of some of the geochemical methods that have been demonstrated to be effective for an existing CO2-EOR (Rangely, CA, USA) and a proposed project at Teapot Dome, WY, USA. Carbon dioxide and CH4 fluxes and shallow soil gas concentrations were measured, followed by nested completions of 10-m deep holes to obtain concentration gradients. The focus at Teapot Dome was the evaluation of faults as pathways for gas seepage in an under-pressured reservoir system. The measurements were supplemented by stable carbon and oxygen isotopic measurements, carbon-14, and limited use of inert gases. The work clearly demonstrates the superiority of CH4 over measurements of CO2 in early detection and quantification of gas seepage. Stable carbon isotopes, carbon-14, and inert gas measurements add to the verification of the deep source. A preliminary accounting at Rangely confirms the importance of CH4 measurements in the MVA application.

Evaluation of Tempranillo and Albariño SO2-free wines produced by different chemical alternatives and winemaking procedures

In this work physical and chemical alternatives to produce SO2 free wines are shown. The use of inactive yeast strains enriched in glutathione, chitosan, dimethyldicarbonate and different hydrolysable and condensed tannins were assessed in Tempranillo and Albariño wines. The time of addition, mixtures of additives and the use of inert gases were evaluated. In general, no significant differences on the sensory quality were shown when compared sulphited and non-sulphited wines. Both physical and chemical treatments were more effective for Tempranillo wines. In the two studied vintages, non-sulphited Tempranillo wines were better valuated than controls, even when wines were produced only using the application of inert gases. No differences were observed when argon was used instead of carbon dioxide as inert gas. Mixtures of seed and skin tannins with inactive dry yeast enriched in glutathione were the most effective treatments. This work may help winemakers to elaborate healthier wines meeting the current consumer demands.

Theoretical investigation of the weak interactions of rare gas atoms with silver clusters by resonance Raman spectroscopy modeling

AbstractThe interactions of rare gas atoms (Rg = Ar, Kr, and Xe) with small neutral and cationic silver clusters have been investigated by density functional methods and the effect of these weak interactions on the resonance Raman spectra of the complexes has been evaluated. The resonance Raman technique that depends on the properties of ground and excited state, seems deeply sensitive to the weak rare gas–metal cluster interactions, and the use of inert gases has been proven to be an excellent approach to recognize the ability of this technique to detect extremely weak interactions. In this work, for , and complexes the IR, normal and resonance Raman spectra have been calculated and the effect of rare gas–cluster stretching vibration ( ) on the pattern and the relative intensities of different spectra have been investigated. The resonance Raman spectra for the weakly interacted complexes (with the interaction energies less than −2.0 kcal/mol) exhibit the vibration with the detectable intensity that its intensity increases by going from Ag6–Ar to Ag6–Xe complex. Moreover, the resonance Raman spectra (based on the excited state gradient approximation) for high intensity nearly degenerate excited states, proved the effect of accumulation of the excited state charge density on the relative intensity of vibration.