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The literature sources dealing with the history of gas hydrate studies and discovery of possible existence of gas hydrate deposits in natural conditions were analyzed. They contain facts proving that within 1966 and 1969 the conditions for formation of hydrates in porous medium were researched at the Department of Gas and Gas Condensate Deposits Development and Exploitation of Gubkin Russian State University of Oil and Gas. The first experiments were set up by the Ukraine-born Yurij F. Makogon, Department Assistant Professor. The results proved possibility of formation and stable existence of gas hydrates in earth’s crust and became a scientific substantiation of natural gas hydrate deposits discovery. In 1969 the exploitation of Messoyakha deposits in Siberia started and it was the first time when the natural gas was derived directly from hydrates. The same year that invention was officially recognized and registered. Following the comprehensive international expert examination the State Committee on Inventions and Findings of the USSR Council of Ministers assumed that the citizens of the USSR Yurij F. Makogon, Andrej A. Trofimuk, Nikolaj V. Cherskij and Viktor G. Vasilev made a discovery described as follows: “Experiments proved previously unknown ability of natural gas to form deposits in the earth’s crust in solid gas hydrate state under definite thermodynamic conditions (Request dated March 19, 1969)”. The authors were presented with diplomas on March 4, 1971. From then onwards the issue of natural gas hydrates existence was widely researched all around the world. In 1985 Yurij F. Makogon became a Professor. Since 1973 he was a head of the gas hydrate laboratory in the All-Russian Scientific Research Institute of Natural Gases and Gas Technologies. Within 1974–1987 he was a head of the gas hydrate laboratory in Oil and Gas Research Institute RAS. In 1992 he was invited by one of the largest universities of the USA to arrange modern laboratory for gas hydrate study. The laboratory was created in the Texas University, USA and in 1995 Yurij Makogon became its head. As far as interest in gas hydrates increases Yurij F. Makogon reports at 27 international congresses and conferences, gives lectures in 45 world leading universities, functions as an academic adviser and participates in different international programs on research and exploitation of gas hydrate deposits in USA, Japan and India. The heritage of the scientist includes 27 patents, eight monographs (four of them were translated and published in the USA and Canada) and more than 270 scientific articles.

(1) Background: New technologies involving gas hydrates under pre-nucleation conditions such as gas separations and storage have become more prominent. This has necessitated the characterization and modeling of the transport properties of such systems. (2) Methodology: This work explored methane hydrate systems under pre-nucleation conditions. All-atom molecular dynamics simulations were used to quantify the performance of the TIP4P/2005 and TIP4P/Ice water models to predict the viscosity, diffusivity, and thermal conductivity using various formulations. (3) Results: Molecular simulation equilibrium was robustly demonstrated using various measures. The Green–Kubo estimation of viscosity outperformed other formulations when combined with TIP4P/Ice, and the same combination outperformed all TIP4P/2005 formulations. The Green–Kubo TIP4P/Ice estimation of viscosity overestimates (by 84% on average) the viscosity of methane hydrate systems under pre-nucleation conditions across all pressures considered (0–5 MPag). The presence of methane was found to increase the average number of hydrogen bonds over time (6.7–7.8%). TIP4P/Ice methane systems were also found to have 16–19% longer hydrogen bond lifetimes over pure water systems. (4) Conclusion: An inherent limitation in the current water force field for its application in the context of transport properties estimations for methane gas hydrate systems. A re-parametrization of the current force field is suggested as a starting point. Until then, this work may serve as a characterization of the deviance in viscosity prediction.

Thermal energy storage (TES) systems using phase change materials (PCMs) are of increasing interest for more efficient energy utilization. Herein, sodium sulfate decahydrate (Na2SO4·10H2O; SSD)/nanofibrillated cellulose (NFC)/graphite PCM composites were prepared by a simple blending method. NFC and graphite were used to improve the performance of SSD-based PCMs by mitigating the phase separation and low thermal conductivity issues. The phase stability, thermal, and structural properties of the prepared PCM composites were investigated. The role of NFC was to thicken and thereby improve phase stability, and to assist dispersion of hydrophobic graphite without aggregation by leveraging its amphiphilic characteristics. The supercooling degree, melting temperature, and enthalpy of 4.2 °C, 31.1 °C, and 121.7 J/g, respectively, were measured for the PCM containing 5 wt% of graphite. Fourier transform-infrared spectroscopy and X-ray diffraction studies indicated that no chemical reactions occurred between the PCM components. The thermal conductivity was enhanced by 250 % when 5 wt% of graphite was added, which improved heat charging during the melting process. Increased hydrogen bonding between fibrils and water molecules enhanced the thermal stability by suppressing water evaporation. Our results indicate that the composite would be an efficient TES system. [ABSTRACT FROM AUTHOR]

Results of numerical investigation of the injection of liquid carbon dioxide into a porous stratum saturated with methane and its gas hydrate, accompanied by the replacement of methane in the methane gas hydrate by carbon dioxide, are presented. A round stratum with an impermeable outer boundary of finite radius was considered. It was established that, depending on the duration of the injection of liquid carbon dioxide into such a stratum, the replacement of methane in the methane gas hydrate by carbon dioxide can proceed with the boiling of carbon dioxide or without it. [ABSTRACT FROM AUTHOR]

This research attempts to empirically investigate the pozzolanic properties of White Cowpea Husk Ash (WCHA), an agricultural biomass waste, at different percentages of its use as partial replacement of cement in concrete. WCHA was obtained after the calcination of white cowpea husk for 3 hours at 5500C. X-ray Florescence (XRF) analysis performed revealed that the sample of WCHA is a Class C pozzolana, which contains 65.4% of the combination of SiO2, Al2O3, and Fe2O3. The WCHA shows increase in consistency with increase in the WCHA content. This was attributed to the high Loss of Ignition (LOI) of WCHA compared to that of the cement. In addition, the results indicated that the initial and final setting time of WCHA - Cement blended concrete increase with increase in the WCHA content. The delay in setting times of WCPA-Cement paste could be attributable to the slower pozzolanic reaction. The density of the concrete decreased as the WCHA content increases. Generally the compressive strength of the WCHA concrete increased with increase in curing age and decreases as the WCHA content increased from a strength of 28.6 to 20.0 N/mm2 giving a percentage reduction of 30.1 %. The strength reduction is also attributed to the modification of the bonding properties of the binders' hydrates. However, the 28 days compressive strength of concrete with up to 10 % WCHA content (26.4 N/mm2) satisfied the design characteristic strength of 25 N/mm2. Beyond this limit, the compressive strength of the concrete fell below the design strength. Hence, 10 % WCHA could be regarded as the optimum dose for grade 25 concrete. [ABSTRACT FROM AUTHOR]

Granulated coal ash is made by granulating fly ash from coal-fired power plants with a small amount of cement and water as binders, which is recommended as an absorbent for hydrogen sulfide and nutrient salts adsorptions. Therefore, granulated coal ash is widely used for improving sediment and water quality in littoral regions. Specifically, a scattered layer of granulated coal ash on the seabed can reduce the diffusion of nutrient salts from sediments to bottom waters. It is believed that a granulated coal ash layer on the seafloor adsorbs nutrient salts, and releases ions, which can form insoluble complexes with ammonium ions. However, the processes by which granulated coal ash affects removal of ammonium ions are still unclear. This study describes the results of laboratory experiments performed to examine the processes related to the suppression of ammonium ions diffused from sediments. In particular, the removal of ammonium ions from aqueous solution (ammonium chloride solution) due to the released ions from granulated coal ash and hydrates present in granulated coal ash is examined. The achievements from this study may provide useful information for expanding the practical uses of granulated coal ash, and for developing a new improved granulated coal ash-derived absorbent. The experimental results showed that the released ions from granulated coal ash have no ability, on their own, to remove ammonium ions from the ammonium chloride solution despite the presence of a small amount of dissolved phosphate derived from granulated coal ash. It was determined that the removal of ammonium ions performed by hydrates present in granulated coal ash. 700°C-heated granulated coal ash (hydrate-removed granulated coal ash) was unable to remove ammonium ions from the ammonium chloride solution. This also ensured that ammonium molecules were unable to adsorb onto granulated coal ash surface. [ABSTRACT FROM AUTHOR]

Global warming is one of the most serious issues the world is currently facing. The major reason is attributed to emission of greenhouse gases and in particular carbon dioxide, CO2. The most promising methods that could allow significant reduction in CO2 emissions are capture and geological storage of CO2. One major concern against storage of CO2 is the possibility of its leakage. One process that could lead to more reliable trapping of CO2 is hydrate formation -- that leads to trapping of CO2 in the solid form. In this study, Machine Learning algorithms and reservoir simulation software were used to conduct sensitivity studies on some of the main reservoir parameters, to understand which characteristics have most impact on stability of CO2 storage in the form of hydrates. The hydrate formation curve calculated by HydraFlash software was considered to be a benchmark for experiments conducted in this study. [ABSTRACT FROM AUTHOR]

Sea spray aerosol (SSA) contributes significantly to natural aerosol particle concentrations globally, in marine areas even dominantly. The potential changes of the omnipresent inorganic fraction of SSA due to atmospheric ageing is largely unexplored. In the atmosphere, SSA may exist as aqueous phase solution droplets or as dried solid or amorphous particles. We demonstrate that ageing of liquid NaCl and artificial sea salt aerosol by exposure to ozone and UV light leads to a substantial decrease in hygroscopicity and cloud activation potential of the dried particles of the same size. The results point towards surface reactions on the liquid aerosols that are more crucial for small particles and the formation of salt structures with water bound within the dried aerosols, termed hydrates. Our findings suggest an increased formation of hydrate forming salts during ageing and the presence of hydrates in dried SSA. Field observations indicate a reduced hygroscopic growth factor of sub-micrometre SSA in the marine atmosphere compared to fresh laboratory generated NaCl or sea salt of the same dry size, which is typically attributed to organic matter or sulphates. Aged inorganic sea salt offers an additional explanation for such a measured reduced hygroscopic growth factor and cloud activation potential. [ABSTRACT FROM AUTHOR]

Benzo [a] pyrene (B[a]P) is a potent mutagen and carcinogen, considered one of the commonest concomitants in the environment. The study aimed to evaluate the effect of catechin hydrate on benzo pyrene-induced kidney toxicity. Thirty-six adult male albino rats were divided into six groups: group I untreated control, group II received 10 mL/kg of corn oil (solvent of benzo [a] pyrene) twice a week, group III received 1 mL/kg 0.5% dimethyl sulfoxide (DMSO) (solvent of catechin) once per day, group IV received 50 mg/kg body weight of benzo[a]pyrene twice a week, group V received 20 mg/kg body weight of catechin in 1 mL/kg 0.5% DMSO once daily, and group VI received both catechin+benzo [a] pyrene with the same doses. All treatment was given by oral gavage for four weeks. At the end of the experiment, blood samples were collected for biochemical investigations, tissues were obtained for genotoxicity, RT-PCR, and histopathological studies. B[a]P exposure induced an increase in serum urea and creatinine levels along with severe renal histopathological changes. Our results showed a subsequent decrease in the antioxidant enzyme activities (catalase and superoxide dismutase), and conversely, (malondialdehyde) levels markedly elevated. Also, B[a]P induced DNA damage as well as activated an apoptotic pathway confirmed by upregulation of Bax, caspase-3, and downregulation of Bcl-2 expression. However, treatment with catechin-corrected kidney functions and antioxidant enzymes as well as regulated apoptosis. Histological results also supported the protective effects of catechin. These findings suggested that catechin hydrate is an effective natural product that attenuates benzo pyrene-induced kidney toxicity. [ABSTRACT FROM AUTHOR]

Herein, the effect of microwave irradiation on the formation of γ-Fe2O3 phase was investigated. The structural and chemical features of the γ-Fe2O3 synthesized via microwave-assisted heat treatment (MWH) were examined in terms of precursors. Three different types of precursors, i.e., FeC2O4∙2H2O (FH), FeOOH, and Fe3O4, were used, and each precursor was heated in a temperature range of 100–300 °C via MWH. Nanocrystalline γ-Fe2O3 powders with a crystallite size of ~ 19 nm were synthesized when the source FH was heat-treated at 120 °C for 20 min by MWH. The activation energy required for the formation of γ-Fe2O3 powders was 21.4 kJ/mol, which is approximately one-third or one-quarter of the activation energy (68.5 and 87.9 kJ/mol) reported for the synthesis of γ-Fe2O3 via conventional heating. The lattice parameter of the synthesized γ-Fe2O3 phase expanded to 8.360 Å at 120 °C, whereas it contracted to 8.351 Å at 200 °C. This variation can be attributed to the content of the surface-absorbed OH group. The values of the saturated magnetization and coercive force of the powders increased by approximately threefold with increasing crystallinity. [ABSTRACT FROM AUTHOR]

Cross-nucleation is a phenomenon where a new crystal nucleates and grows upon the surface of a different polymorph. Previous studies indicate that faster growth rate of the new crystal is a necessary but not sufficient condition for cross-nucleation. The thermodynamic stability of the different polymorphs can also affect cross-nucleation by modulating the rates of crystal growth. The interplay between thermodynamic stability of the polymorphs involved, the growth rate of the crystals, and the need for creation of an interfacial transition layer that seamlessly connects the two structures has not yet been fully elucidated. Predicting cross-nucleation is particularly challenging for clathrate hydrates, for which there are sometimes several polymorphs with similar stability and for which growth rates are not known. In this work, we use molecular dynamics simulations to investigate which factor (stability, growth rate, or formation of interfacial transition layer) controls cross-nucleation between the four known Frank-Kasper clathrate hydrate polymorphs: sI, sII, TS, and HS-I.We investigate the growth and cross-nucleation of these four hydrates filled with a set of guest molecules that produce different order of stabilities for the four crystal structures. We determine that the growth rate of sII clathrate is the fastest, followed by TS, HS-I, and sI. We find that cross-nucleation into or from sII clathrates is preceded by the formation of an interfacial transition layer at the seed crystal/liquid interface because sII does not share a crystal plane with sI, HS-I, or TS. Cross-nucleation between the latter three can occur seamlessly and is determined only by their growth rates. Our results indicate that nucleation of an interfacial transition layer between non-matching polymorphs can control cross-nucleation or lack thereof under conditions of small driving force. Under conditions of sufficient supercooling clathrate hydrate polymorphs cross-nucleate into the fastest growing phase even if that new phase is less stable and does not share a common crystal plane with the initial polymorph. [ABSTRACT FROM AUTHOR]