Hydration mechanism and leaching behavior of bauxite-calcination-method red mud-coal gangue based cementitious materials

International Nuclear Information System (INIS)

Zhang, Na; Li, Hongxu; Liu, Xiaoming

2016-01-01

Highlights: • Nanocrystalline regions in size of ∼5 nm were found in the amorphous C-A-S-H gel. • A hydration model was proposed to clarify the hydration mechanism. • The developed cementitious materials are environmentally acceptable. - Abstract: A deep investigation on the hydration mechanism of bauxite-calcination-method red mud-coal gangue based cementitious materials was conducted from viewpoints of hydration products and hydration heat analysis. As a main hydration product, the microstructure of C-A-S-H gel was observed using high resolution transmission electron microscopy. It was found that the C-A-S-H gel is composed of amorphous regions and nanocrystalline regions. Most of regions in the C-A-S-H gel are amorphous with continuous distribution, and the nanocrystalline regions on scale of ∼5 nm are dispersed irregularly within the amorphous regions. The hydration heat of red mud-coal gangue based cementitious materials is much lower than that of the ordinary Portland cement. A hydration model was proposed for this kind of cementitious materials, and the hydration process mainly consists of four stages which are dissolution of materials, formation of C-A-S-H gels and ettringite, cementation of hydration products, and polycondensation of C-A-S-H gels. There are no strict boundaries among these four basic stages, and they proceed crossing each other. Moreover, the leaching toxicity tests were also performed to prove that the developed red mud-coal gangue based cementitious materials are environmentally acceptable.

Hydration mechanism and leaching behavior of bauxite-calcination-method red mud-coal gangue based cementitious materials

Energy Technology Data Exchange (ETDEWEB)

Zhang, Na; Li, Hongxu [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Xiaoming, E-mail: liuxm@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China)

2016-08-15

Highlights: • Nanocrystalline regions in size of ∼5 nm were found in the amorphous C-A-S-H gel. • A hydration model was proposed to clarify the hydration mechanism. • The developed cementitious materials are environmentally acceptable. - Abstract: A deep investigation on the hydration mechanism of bauxite-calcination-method red mud-coal gangue based cementitious materials was conducted from viewpoints of hydration products and hydration heat analysis. As a main hydration product, the microstructure of C-A-S-H gel was observed using high resolution transmission electron microscopy. It was found that the C-A-S-H gel is composed of amorphous regions and nanocrystalline regions. Most of regions in the C-A-S-H gel are amorphous with continuous distribution, and the nanocrystalline regions on scale of ∼5 nm are dispersed irregularly within the amorphous regions. The hydration heat of red mud-coal gangue based cementitious materials is much lower than that of the ordinary Portland cement. A hydration model was proposed for this kind of cementitious materials, and the hydration process mainly consists of four stages which are dissolution of materials, formation of C-A-S-H gels and ettringite, cementation of hydration products, and polycondensation of C-A-S-H gels. There are no strict boundaries among these four basic stages, and they proceed crossing each other. Moreover, the leaching toxicity tests were also performed to prove that the developed red mud-coal gangue based cementitious materials are environmentally acceptable.

Hydration rate and strength development of low-heat type portland cement mortar mixed with pozzolanic materials

International Nuclear Information System (INIS)

Matsui, Jun

1998-01-01

Recently, low-heat type Portland cement was specified in Japan Industrial Standards (JIS). Its hydration proceeds slowly. The results of the research so far obtained indicate that slow hydration of cement and mixing of pozzolanic materials with cement make micro-structure of harded cement paste dense and durable. In this study, a blended cement using low-heat type Portland cement and some of pozzolanic materials has been newly developed and its strength property and hydration ratio were checked. The followings are conclusion. (1) Hydration rate of cement paste varies with the replacement ratio of pozzolanic materials. (2) A good liner relationship between strength and total hydration rate of cement paste was observed. (3) A proper replacement ratio of both base-cement and pozzolanic material for manufacturing a blended cement is 50%. (author)

A new aluminium-hydrate species in hydrated Portland cements characterized by 27Al and 29Si MAS NMR spectroscopy

International Nuclear Information System (INIS)

Andersen, Morten Daugaard; Jakobsen, Hans J.; Skibsted, Jorgen

2006-01-01

Recent 27 Al MAS NMR studies of hydrated Portland cements and calcium-silicate-hydrate (C-S-H) phases have shown a resonance from Al in octahedral coordination, which cannot be assigned to the well-known aluminate species in hydrated Portland cements. This resonance, which exhibits the isotropic chemical shift δ iso = 5.0 ppm and the quadrupole product parameter P Q = 1.2 MHz, has been characterized in detail by 27 Al MAS and 27 Al{ 1 H} CP/MAS NMR for different hydrated white Portland cements and C-S-H phases. These experiments demonstrate that the resonance originates from an amorphous or disordered aluminate hydrate which contains Al(OH) 6 3- or O x Al(OH) 6-x (3+x)- units. The formation of the new aluminate hydrate is related to the formation of C-S-H at ambient temperatures, however, it decomposes by thermal treatment at temperatures of 70-90 o C. From the experiments in this work it is proposed that the new aluminate hydrate is either an amorphous/disordered aluminate hydroxide or a calcium aluminate hydrate, produced as a separate phase or as a nanostructured surface precipitate on the C-S-H phase. Finally, the possibilities of Al 3+ for Ca 2+ substitution in the principal layers and interlayers of the C-S-H structure are discussed

Gas Hydrate Characterization from a 3D Seismic Dataset in the Eastern Deepwater Gulf of Mexico

Energy Technology Data Exchange (ETDEWEB)

McConnell, Dan

2017-10-26

The presence of a gas hydrate petroleum system and seismic attributes derived from 3D seismic data are used for the identification and characterization of gas hydrate deposits in the deepwater eastern Gulf of Mexico. In the central deepwater Gulf of Mexico (GoM), logging while drilling (LWD) data provided insight to the amplitude response of gas hydrate saturation in sands, which could be used to characterize complex gas hydrate deposits in other sandy deposits. In this study, a large 3D seismic data set from equivalent and distal Plio-Pleistocene sandy channel deposits in the deepwater eastern Gulf of Mexico is screened for direct hydrocarbon indicators for gas hydrate saturated sands.

Hydration water and microstructure in calcium silicate and aluminate hydrates

International Nuclear Information System (INIS)

Fratini, Emiliano; Ridi, Francesca; Chen, Sow-Hsin; Baglioni, Piero

2006-01-01

angle x-ray scattering (WAXD) that characterize how additives affect both the hydrated microstructure development and the original grain size. In particular, SPs alter the morphology of the hydrated phases, which no longer grow with the classic fibrillar structure on the grain surface, but nucleate in solution as globular structures. All this information converges in a quantitative, and at molecular level, description of the mechanisms involved in the setting process of one of the materials most widely used by human beings

Offshore Antarctic Peninsula Gas Hydrate Reservoir Characterization by Geophysical Data Analysis

Directory of Open Access Journals (Sweden)

Michela Giustiniani

2010-12-01

Full Text Available A gas hydrate reservoir, identified by the presence of the bottom simulating reflector, is located offshore of the Antarctic Peninsula. The analysis of geophysical dataset acquired during three geophysical cruises allowed us to characterize this reservoir. 2D velocity fields were obtained by using the output of the pre-stack depth migration iteratively. Gas hydrate amount was estimated by seismic velocity, using the modified Biot-Geerstma-Smit theory. The total volume of gas hydrate estimated, in an area of about 600 km2, is in a range of 16 × 109–20 × 109 m3. Assuming that 1 m3 of gas hydrate corresponds to 140 m3 of free gas in standard conditions, the reservoir could contain a total volume that ranges from 1.68 to 2.8 × 1012 m3 of free gas. The interpretation of the pre-stack depth migrated sections and the high resolution morpho-bathymetry image allowed us to define a structural model of the area. Two main fault systems, characterized by left transtensive and compressive movement, are recognized, which interact with a minor transtensive fault system. The regional geothermal gradient (about 37.5 °C/km, increasing close to a mud volcano likely due to fluid-upwelling, was estimated through the depth of the bottom simulating reflector by seismic data.

Hydration characteristics of zirconium oxide replaced Portland cement for use as a root-end filling material.

Science.gov (United States)

Camilleri, J; Cutajar, A; Mallia, B

2011-08-01

Zirconium oxide can be added to dental materials rendering them sufficiently radiopaque. It can thus be used to replace the bismuth oxide in mineral trioxide aggregate (MTA). Replacement of Portland cement with 30% zirconium oxide mixed at a water/cement ratio of 0.3 resulted in a material with adequate physical properties. This study aimed at investigating the microstructure, pH and leaching in physiological solution of Portland cement replaced zirconium oxide at either water-powder or water-cement ratios of 0.3 for use as a root-end filling material. The hydration characteristics of the materials which exhibited optimal behavior were evaluated. Portland cement replaced by zirconium oxide in varying amounts ranging from 0 to 50% in increments of 10 was prepared and divided into two sets. One set was prepared at a constant water/cement ratio while the other set at a constant water/powder ratio of 0.3. Portland cement and MTA were used as controls. The materials were analyzed under the scanning electron microscope (SEM) and the hydration products were determined. X-ray energy dispersive analysis (EDX) was used to analyze the elemental composition of the hydration products. The pH and the amount of leachate in Hank's balanced salt solution (HBSS) were evaluated. A material that had optimal properties that satisfied set criteria and could replace MTA was selected. The microstructure of the prototype material and Portland cement used as a control was assessed after 30 days using SEM and atomic ratio diagrams of Al/Ca versus Si/Ca and S/Ca versus Al/Ca were plotted. The hydration products of Portland cement replaced with 30% zirconium oxide mixed at water/cement ratio of 0.3 were calcium silicate hydrate, calcium hydroxide and minimal amounts of ettringite and monosulphate. The calcium hydroxide leached in HBSS solution resulted in an increase in the pH value. The zirconium oxide acted as inert filler and exhibited no reaction with the hydration by-products of Portland

Material Research on Salt Hydrates for Seasonal Heat Storage Application in a Residential Environment

Energy Technology Data Exchange (ETDEWEB)

Ferchaud, C.J.; Zondag, H.A.; De Boer, R. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

2013-09-15

Water vapor sorption in salt hydrates is a promising method to realize seasonal solar heat storage in the residential sector. Several materials already showed promising performance for this application. However, the stability of these materials needs to be improved for long-term (30 year) application in seasonal solar heat storages. The purpose of this article is to identify the influence of the material properties of the salt hydrates on the performance and the reaction kinetics of the sorption process. The experimental investigation presented in this article shows that the two salt hydrates Li2SO4.H2O and CuSO4.5H2O can store and release heat under the operating conditions of a seasonal solar heat storage in a fully reversible way. However, these two materials show differences in terms of energy density and reaction kinetics. Li2SO4.H2O can release heat with an energy density of around 0.80 GJ/m{sup 3} within 4 hours of rehydration at 25C, while CuSO4.5H2O needs around 130 hours at the same temperature to be fully rehydrated and reaches an energy density of 1.85 GJ/m{sup 3}. Since the two salts are dehydrated and hydrated under the same conditions, this difference in behavior is directly related to the intrinsic properties of the materials.

Development and characterization of morin hydrate loaded microemulsion for the management of Alzheimer's disease.

Science.gov (United States)

Sharma, Dheeraj; Singh, Manpreet; Kumar, Punnet; Vikram, Vir; Mishra, Neeraj

2017-12-01

The aim of this study is to prepare and characterize intranasal delivery of morin hydrate loaded microemulsion for the management of Alzheimer's diseases. After intranasal delivery, brain and blood drug concentrations were found to be higher for optimized morin hydrate loaded microemulsion as compared to plain morin hydrate. Significant (P microemulsion as compared to sham control group. Daily chronic treatment with morin loaded microemulsion till the 21st day significantly increased the memory in wistar rats with STZ-induced dementia.

Microstructure, characterizations, functionality and compressive strength of cement-based materials using zinc oxide nanoparticles as an additive

Energy Technology Data Exchange (ETDEWEB)

Nochaiya, Thanongsak [Department of Physics, Faculty of Science, Naresuan University, Phitsanulok 65000 (Thailand); Sekine, Yoshika [Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Choopun, Supab [Applied Physics Research Laboratory, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Chaipanich, Arnon, E-mail: arnon.chaipanich@cmu.ac.th [Advanced Cement-Based Materials Research Unit, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2015-05-05

Highlights: • Nano zinc oxide was used as an additive material. • Microstructure and phase characterization of pastes were characterized using SEM and XRD. • TGA and FTIR were also used to determine the hydration reaction. • Compressive strength of ZnO mixes was found to increase at 28 days. - Abstract: Zinc oxide nanoparticles as a nanophotocatalyst has great potential for self-cleaning applications in concrete structures, its effects on the cement hydration, setting time and compressive strength are also important when using it in practice. This paper reports the effects of zinc oxide nanoparticles, as an additive material, on properties of cement-based materials. Setting time, compressive strength and porosity of mortars were investigated. Microstructure and morphology of pastes were characterized using scanning electron microscope and X-ray diffraction (XRD), respectively. Moreover, thermal gravimetric analysis (TGA) and Fourier-transform infrared spectrometer (FTIR) were also used to determine the hydration reaction. The results show that Portland cement paste with additional ZnO was found to slightly increase the water requirement while the setting time presented prolongation period than the control mix. However, compressive strength of ZnO mixes was found to be higher than that of PC mix up to 15% (at 28 days) via filler effect. Microstructure, XRD and TGA results of ZnO pastes show less hydration products before 28 days but similar at 28 days. In addition, FTIR results confirmed the retardation when ZnO was partially added in Portland cement pastes.

Microstructure, characterizations, functionality and compressive strength of cement-based materials using zinc oxide nanoparticles as an additive

International Nuclear Information System (INIS)

Nochaiya, Thanongsak; Sekine, Yoshika; Choopun, Supab; Chaipanich, Arnon

2015-01-01

Highlights: • Nano zinc oxide was used as an additive material. • Microstructure and phase characterization of pastes were characterized using SEM and XRD. • TGA and FTIR were also used to determine the hydration reaction. • Compressive strength of ZnO mixes was found to increase at 28 days. - Abstract: Zinc oxide nanoparticles as a nanophotocatalyst has great potential for self-cleaning applications in concrete structures, its effects on the cement hydration, setting time and compressive strength are also important when using it in practice. This paper reports the effects of zinc oxide nanoparticles, as an additive material, on properties of cement-based materials. Setting time, compressive strength and porosity of mortars were investigated. Microstructure and morphology of pastes were characterized using scanning electron microscope and X-ray diffraction (XRD), respectively. Moreover, thermal gravimetric analysis (TGA) and Fourier-transform infrared spectrometer (FTIR) were also used to determine the hydration reaction. The results show that Portland cement paste with additional ZnO was found to slightly increase the water requirement while the setting time presented prolongation period than the control mix. However, compressive strength of ZnO mixes was found to be higher than that of PC mix up to 15% (at 28 days) via filler effect. Microstructure, XRD and TGA results of ZnO pastes show less hydration products before 28 days but similar at 28 days. In addition, FTIR results confirmed the retardation when ZnO was partially added in Portland cement pastes

Preparation and characterization of hybrid materials from natural chrysotile

International Nuclear Information System (INIS)

Giraldelli, M.G.; Silva, M.L.C.P.

2010-01-01

Special attention has been given to the development of new materials from natural chrysotile. This fiber has about 40% silicon oxide in its structure with an outer layer of brucite (MgOH 2 ). With the aim of obtaining a material with a more uniform structure, acid leaching was performed to remove the outer layer of brucite, resulting in a silicon oxide hydrate. This material was used as support for the deposition of Nb 2 O 5 .nH 2 O. The Nb 2 O 5 .nH 2 O was prepared by conventional precipitation using as starting material niobium metallic. In this study, we performed the synthesis and characterization of the material SiO 2 .nH 2 O / Nb 2 O 5 .nH 2 O 1:1. Both chrysotile as niobium are widely available national resources, which confirms the economic viability of resource use. The materials studied were characterized by XRD, SEM and TG/DTG. (author)

Grain-scale imaging and compositional characterization of cryo-preserved India NGHP 01 gas-hydrate-bearing cores

Science.gov (United States)

Stern, Laura A.; Lorenson, T.D.

2014-01-01

We report on grain-scale characteristics and gas analyses of gas-hydrate-bearing samples retrieved by NGHP Expedition 01 as part of a large-scale effort to study gas hydrate occurrences off the eastern-Indian Peninsula and along the Andaman convergent margin. Using cryogenic scanning electron microscopy, X-ray spectroscopy, and gas chromatography, we investigated gas hydrate grain morphology and distribution within sediments, gas hydrate composition, and methane isotopic composition of samples from Krishna–Godavari (KG) basin and Andaman back-arc basin borehole sites from depths ranging 26 to 525 mbsf. Gas hydrate in KG-basin samples commonly occurs as nodules or coarse veins with typical hydrate grain size of 30–80 μm, as small pods or thin veins 50 to several hundred microns in width, or disseminated in sediment. Nodules contain abundant and commonly isolated macropores, in some places suggesting the original presence of a free gas phase. Gas hydrate also occurs as faceted crystals lining the interiors of cavities. While these vug-like structures constitute a relatively minor mode of gas hydrate occurrence, they were observed in near-seafloor KG-basin samples as well as in those of deeper origin (>100 mbsf) and may be original formation features. Other samples exhibit gas hydrate grains rimmed by NaCl-bearing material, presumably produced by salt exclusion during original hydrate formation. Well-preserved microfossil and other biogenic detritus are also found within several samples, most abundantly in Andaman core material where gas hydrate fills microfossil crevices. The range of gas hydrate modes of occurrence observed in the full suite of samples suggests a range of formation processes were involved, as influenced by local in situconditions. The hydrate-forming gas is predominantly methane with trace quantities of higher molecular weight hydrocarbons of primarily microbial origin. The composition indicates the gas hydrate is Structure I.

Characterizing the hydration state of L-threonine in solution using terahertz time-domain attenuated total reflection spectroscopy

Science.gov (United States)

Huang, Huachuan; Liu, Qiao; Zhu, Liguo; Li, Zeren

2018-01-01

The hydration of biomolecules is closely related to the dynamic process of their functional expression, therefore, characterizing hydration phenomena is a subject of keen interest. However, direct measurements on the global hydration state of biomolecules couldn't have been acquired using traditional techniques such as thermodynamics, ultrasound, microwave spectroscopy or viscosity, etc. In order to realize global hydration characterization of amino acid such as L-threonine, terahertz time-domain attenuated total reflectance spectroscopy (THz-TDS-ATR) was adopted in this paper. By measuring the complex permittivity of L-threonine solutions with various concentrations in the THz region, the hydration state and its concentration dependence were obtained, indicating that the number of hydrous water decreased with the increase of concentration. The hydration number was evaluated to be 17.8 when the molar concentration of L-threonine was 0.34 mol/L, and dropped to 13.2 when the molar concentration increased to 0.84 mol/L, when global hydration was taken into account. According to the proposed direct measurements, it is believed that the THz-TDS-ATR technique is a powerful tool for studying the picosecond molecular dynamics of amino acid solutions.

Design, characterization, and clinical evaluation of argan oil nanostructured lipid carriers to improve skin hydration.

Science.gov (United States)

Tichota, Deise Michele; Silva, Ana Catarina; Sousa Lobo, José Manuel; Amaral, Maria Helena

2014-01-01

Given its advantages in skin application (eg, hydration, antiaging, and protection), argan oil could be used in both dermatological and cosmetic formulations. Therefore, the preparation of nanostructured lipid carriers (NLCs) using argan oil as a liquid lipid is a promising technique, since the former constitute well-established systems for dermal delivery. The aim of this work was to develop a topical formulation of argan oil NLCs to improve skin hydration. Firstly an NLC dispersion was developed and characterized, and afterward an NLC-based hydrogel was prepared. The in vivo evaluation of the suitability of the prepared formulation for the proposed application was assessed in volunteers, by measuring different skin-surface parameters for 1 month. An argan oil NLC-based hydrogel formulation was successfully prepared and characterized. Moreover, the entrapment of the NLCs in the hydrogel net did not affect their colloidal sizes. Additionally, it was observed that this formulation precipitated an increase in skin hydration of healthy volunteers. Therefore, we concluded that the preparation of NLC systems using argan oil as the liquid lipid is a promising strategy, since a synergistic effect on the skin hydration was obtained (ie, NLC occlusion plus argan oil hydration).

Methane Hydrate in Confined Spaces: An Alternative Storage System.

Science.gov (United States)

Borchardt, Lars; Casco, Mirian Elizabeth; Silvestre-Albero, Joaquin

2018-03-14

Methane hydrate inheres the great potential to be a nature-inspired alternative for chemical energy storage, as it allows to store large amounts of methane in a dense solid phase. The embedment of methane hydrate in the confined environment of porous materials can be capitalized for potential applications as its physicochemical properties, such as the formation kinetics or pressure and temperature stability, are significantly changed compared to the bulk system. We review this topic from a materials scientific perspective by considering porous carbons, silica, clays, zeolites, and polymers as host structures for methane hydrate formation. We discuss the contribution of advanced characterization techniques and theoretical simulations towards the elucidation of the methane hydrate formation and dissociation process within the confined space. We outline the scientific challenges this system is currently facing and look on possible future applications for this technology. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental Setup to Characterize Bentonite Hydration Processes

International Nuclear Information System (INIS)

Bru, A.; Casero, D.; Pastor, J. M.

2001-01-01

We present an experimental setup to follow-up the hydration process of a bentonite. Clay samples, of 2 cm x 12 cm x 12 cm, were made and introduced in a Hele-Shaw cell with two PMM windows and two steel frames. In hydration experiments, a fluid enters by an orifice in the frame, located both at the top and the bottom of the cell, to perform hydration in both senses. To get a uniform hydration we place a diffuser near the orifice. Volume influxes in hydration cells are registered in time. The evolution of the developed interface was recorded on a videotape. The video cameras was fixed to a holder so that the vertical direction in the monitor was the same as the direction of the larger extension of the cell. (Author) 6 refs

Modeling the influence of limestone addition on cement hydration

Directory of Open Access Journals (Sweden)

Ashraf Ragab Mohamed

2015-03-01

Full Text Available This paper addresses the influence of using Portland limestone cement “PLC” on cement hydration by characterization of its microstructure development. The European Standard EN 197-1:2011 and Egyptian specification ESS 4756-1/2009 permit the cement to contain up to 20% ground limestone. The computational tools assist in better understanding the influence of limestone additions on cement hydration and microstructure development to facilitate the acceptance of these more economical and ecological materials. μic model has been developed to enable the modeling of microstructural evolution of cementitious materials. In this research μic model is used to simulate both the influence of limestone as fine filler, providing additional surfaces for the nucleation and growth of hydration products. Limestone powder also reacts relatively slow with hydrating cement to form monocarboaluminate (AFmc phase, similar to the mono-sulfoaluminate (AFm phase formed in ordinary Portland cement. The model results reveal that limestone cement has accelerated cement hydration rate, previous experimental results and computer model “cemhyd3d” are used to validate this model.

Dehydration and hydration behavior of metal-salt-modified materials for chemical heat pumps

International Nuclear Information System (INIS)

Ishitobi, Hirokazu; Uruma, Keirei; Takeuchi, Masato; Ryu, Junichi; Kato, Yukitaka

2013-01-01

Lithium chloride (LiCl) modified magnesium hydroxide (Mg(OH) 2 ) is a potential new material for chemical heat pumps. However, there is insufficient information concerning its dehydration and hydration behavior. In this study, the dehydration and hydration reactions, corresponding to the heat storage and the heat output operations, respectively, of authentic Mg(OH) 2 and LiCl-modified Mg(OH) 2 were investigated by thermogravimetric methods and near infrared spectroscopy. The dehydration of authentic Mg(OH) 2 proceeded as a one-step reaction. In contrast, the dehydration of LiCl-modified Mg(OH) 2 occurred in two steps. The dehydration reaction rates were increased by LiCl modification of the Mg(OH) 2 surface, while the activation energy for the first-order dehydration reaction was lowered. The mechanism for the hydration reaction of magnesium oxide (MgO) was different to that for the hydration of LiCl-modified MgO. This difference was explained by the effect of the LiCl on the MgO particle surface. - Highlights: ► LiCl-modified Mg(OH) 2 is a candidate material for chemical heat pumps. ► The dehydration reaction of LiCl-modified Mg(OH) 2 is a two-step reaction. ► The dehydration reaction of Mg(OH) 2 was enhanced by LiCl modification. ► The hydration mechanisms of authentic MgO and LiCl-modified MgO were different.

Physicochemical properties and thermal stability of quercetin hydrates in the solid state

Energy Technology Data Exchange (ETDEWEB)

Borghetti, G.S., E-mail: greicefarm@yahoo.com.br [Programa de Pos-Graduacao em Ciencias Farmaceuticas, Faculdade de Farmacia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, CEP 90.610-000, Porto Alegre, RS (Brazil); Carini, J.P. [Programa de Pos-Graduacao em Ciencias Farmaceuticas, Faculdade de Farmacia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, CEP 90.610-000, Porto Alegre, RS (Brazil); Honorato, S.B.; Ayala, A.P. [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, CEP 60.455-970, Fortaleza, CE (Brazil); Moreira, J.C.F. [Departamento de Bioquimica, Instituto de Ciencias Basicas da Saude, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600, CEP 90035-003, Porto Alegre, RS (Brazil); Bassani, V.L. [Programa de Pos-Graduacao em Ciencias Farmaceuticas, Faculdade de Farmacia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, CEP 90.610-000, Porto Alegre, RS (Brazil)

2012-07-10

Highlights: Black-Right-Pointing-Pointer Quercetin raw materials may present different degree of hydration. Black-Right-Pointing-Pointer Thermal stability of quercetin in the solid state depends on its degree of hydration. Black-Right-Pointing-Pointer Quercetin dehydrate is thermodynamically more stable than the other crystal forms. - Abstract: In the present work three samples of quercetin raw materials (QCTa, QCTb and QCTc), purchased from different Brazilian suppliers, were characterized employing scanning electron microscopy, Raman spectroscopy, simultaneous thermogravimetry and infrared spectroscopy, differential scanning calorimetry, and variable temperature-powder X-ray diffraction, in order to know their physicochemical properties, specially the thermal stability in solid state. The results demonstrated that the raw materials of quercetin analyzed present distinct crystalline structures, ascribed to the different degree of hydration of their crystal lattice. The thermal stability of these quercetin raw materials in the solid state was highly dependent on their degree of hydration, where QCTa (quercetin dihydrate) was thermodynamically more stable than the other two samples.

Accelerated hydration of high silica cements

International Nuclear Information System (INIS)

Walker, Colin; Yui, Mikazu

2012-01-01

Current Japanese designs for high level radioactive waste (HLW) repositories anticipate the use of both bentonite (buffer and backfill material) and cement based materials. Using hydrated Ordinary Portland Cement (OPC) as a grouting material is undesirable because the associated high pH buffer will have an undisputed detrimental effect on the performance of the bentonite buffer and backfill and of the host rock by changing its porosity. Instead, hydrated low pH cement (LopHC) grouting materials are being developed to provide a pH inferior or equal to 11 to reduce these detrimental effects. LopHC grouting materials use mixtures of superfine OPC (SOPC) clinker and silica fume (SF), and are referred as high silica cements (HSC). The focus of the present study was to identify the development of the unhydrated and hydrated mineral assemblage and the solution chemistry during the hydration of HSC. Since hydration experiments of cementitious materials are notably slow, a ball mill was used to accelerate hydration. This was done for two reasons. Firstly, to develop a method to rapidly hydrate cement based materials without the need for higher temperatures (which can alter the mineral assemblage), and secondly, to ensure that the end point of hydration was reached in a reasonable time frame and so to realize the final mineralogy and solution chemistry of hydrated HSC

Hydrate bearing clayey sediments: Formation and gas production concepts

KAUST Repository

Jang, Jaewon; Santamarina, Carlos

2016-01-01

Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

Hydrate bearing clayey sediments: Formation and gas production concepts

KAUST Repository

Jang, Jaewon

2016-06-20

Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

Multicomponent seismic methods for characterizing gas hydrate occurrences and systems in deep-water Gulf of Mexico

Science.gov (United States)

Haines, Seth S.; Lee, Myung W.; Collett, Timothy S.; Hardage, Bob A.

2011-01-01

In-situ characterization and quantification of natural gas hydrate occurrences remain critical research directions, whether for energy resource, drilling hazard, or climate-related studies. Marine multicomponent seismic data provide the full seismic wavefield including partial redundancy, and provide a promising set of approaches for gas hydrate characterization. Numerous authors have demonstrated the possibilities of multicomponent data at study sites around the world. We expand on this work by investigating the utility of very densely spaced (10’s of meters) multicomponent receivers (ocean-bottom cables, OBC, or ocean-bottom seismometers, OBS) for gas hydrate studies in the Gulf of Mexico and elsewhere. Advanced processing techniques provide high-resolution compressional-wave (PP) and converted shearwave (PS) reflection images of shallow stratigraphy, as well as P-wave and S-wave velocity estimates at each receiver position. Reflection impedance estimates can help constrain velocity and density, and thus gas hydrate saturation. Further constraint on velocity can be determined through identification of the critical angle and associated phase reversal in both PP and PS wideangle data. We demonstrate these concepts with examples from OBC data from the northeast Green Canyon area and numerically simulated OBS data that are based on properties of known gas hydrate occurrences in the southeast (deeper water) Green Canyon area. These multicomponent data capabilities can provide a wealth of characterization and quantification information that is difficult to obtain with other geophysical methods.

Application of the electrical characterization to the study of the hydrated phases of the cement with coal bottom ash; Aplicacion de la caracterizacion electrica al estudio de las fases hidratadas de cemento con adicion de escorias de centrales termicas

Energy Technology Data Exchange (ETDEWEB)

Menendez, E.; Frutos, J. de; Alvaro, A. M.

2014-02-01

The present paper investigates the influence of using Bottom and Fly Ash as partial replacement of cement in the hydration process. Through measurements of electrical impedance spectroscopy (EIS) and X -ray diffraction (XRD), we analyze from the early stages to the hydration process to the end. Values of EIS, XRD and its relation, are used to determine transformation of hydrated phases, and for each of the substitutions, is indicated as modified the hydrated phase as a function of time and compared it with the reference material. It also proves the relevance of using EIS measures in real time, and as non destructive testing to characterize the hydration process of these materials. (Author)

Characterizing Natural Gas Hydrates in the Deep Water Gulf of Mexico: Applications for Safe Exploration and Production Activities

Energy Technology Data Exchange (ETDEWEB)

Bent, Jimmy

2014-05-31

In 2000 Chevron began a project to learn how to characterize the natural gas hydrate deposits in the deep water portion of the Gulf of Mexico (GOM). Chevron is an active explorer and operator in the Gulf of Mexico and is aware that natural gas hydrates need to be understood to operate safely in deep water. In August 2000 Chevron worked closely with the National Energy Technology Laboratory (NETL) of the United States Department of Energy (DOE) and held a workshop in Houston, Texas to define issues concerning the characterization of natural gas hydrate deposits. Specifically, the workshop was meant to clearly show where research, the development of new technologies, and new information sources would be of benefit to the DOE and to the oil and gas industry in defining issues and solving gas hydrate problems in deep water.

Characterization of methane-hydrate formation inferred from insitu Vp-density relationship for hydrate-bearing sediment cores obtained off the eastern coast of India

Science.gov (United States)

Kinoshita, M.; Hamada, Y.; Hirose, T.; Yamada, Y.

2017-12-01

In 2015, the Indian National Gas Hydrate Program (NGHP) Drilling Expedition 02 was carried out off the eastern margin of the Indian Peninsula in order to investigate distribution and occurrence of gas hydrates. From 25 drill sites, downhole logging data, cored samples, and drilling performance data were collected. One of the target areas (area B) is located on the axial and flank of an anticline, where the BSR is identified 100 m beneath the summit of anticline. 3 sites were drilled in the crest. The lower potential hydrate zone II was suggested by downhole logging (LWD) at 270-290 m below seafloor across the top of anticline. Core samples from this interval is characterized by a higher natural gamma radiation, gamma-ray-based higher bulk density and lower porosity, and higher electrical resistivity. All these features are in good agreement with LWD results. During this expedition, numerous special core sampling operations (PCAT) were carried out, keeping its insitu pressure in a pressure-tight vessel. They enabled acquiring insitu P-wave velocity and gamma-ray attenuation density measurements. In-situ X-CT images exhibit very clear hydrate distribution as lower density patches. Hydrate-bearing sediments exhibit a Vp-density trend that is clearly different from the ordinary formation. Vp values are significantly higher than 2 km/s whereas the density remains constant at 2-2.2 g/cm3 in hydrate zones. At some hydrate-bearing sediments, we noticed that Vp is negatively correlated to the density in the deeper portion (235-285 mbsf). On the other hand, in the shallower portion they are positively correlated. From lithostratigraphy the shallower portion consists of sand, whereas deeper portion are silty-clay dominant. We infer that the sand-dominant, shallower hydrate is a pore-filling type, and Vp is correlated positively to density. On the other hand, the clay-dominant, deeper hydrate is filled in vertical veins, and Vp is negatively correlated to density. Negative

Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag

Energy Technology Data Exchange (ETDEWEB)

Zhang, Na; Li, Hongxu [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China); Zhao, Yazhao [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Xiaoming, E-mail: liuxm@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083 (China)

2016-04-05

Highlights: • Cementitious material was designed according to [SiO{sub 4}] polymerization degree of raw materials. • The cementitious material composed of calcium silicate slag yields excellent physical and mechanical properties. • Amorphous C–A–S–H gel and rod-like ettringite are predominantly responsible for the strength development. • Leaching toxicity and radioactivity tests show the cementitious material is environmentally acceptable. - Abstract: Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al{sub 2}O{sub 3} from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C–A–S–H gel, rod-like ettringite and hexagonal-sheet Ca(OH){sub 2} with small amount of zeolite-like minerals such as CaAl{sub 2}Si{sub 2}O{sub 8}·4H{sub 2}O and Na{sub 2}Al{sub 2}Si{sub 2}O{sub 8}·H{sub 2}O. As the predominant hydration products, rod-like ettringite and amorphous C–A–S–H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities.

Seismic Characterization and Continuity Analysis of Gas Hydrate Horizons Near the Mallik Research Wells, Mackenzie Delta, Canada

Science.gov (United States)

Bellefleur, G.; Riedel, M.; Brent, T.

2005-12-01

Gas hydrate deposits in arctic environment generally lack the BSR signature diagnostic of their presence in marine seismic data. The absence of the BSR signature complicates the estimation of the resources within or below the permafrost and the determination of their potential impact on future energy supplies, geohazard and climate change. We present results from a detailed seismic characterization of three gas hydrate horizons (A, B and C) intersected below the permafrost in five wells of the Mallik gas hydrate field located in the Mackenzie delta (Northwest Territories, Canada). The detailed seismic characterization included attribute analyses, synthetic modeling and acoustic impedance inversion and allowed estimation of the lateral continuity of the three horizons in the vicinity of the wells. Vertical Seismic Profiling (VSP) data, 3D and 2D industry seismic data and the 5L/2L-38 geophysical logs (density, P-wave sonic velocity) were used for this study. Synthetic modeling using the sonic and density logs reveals that the base of the lower gas hydrate horizons B and C can be identified on the industry 3D and 2D seismic sections as prominent isolated reflections. The uppermost gas hydrate occurrence (horizon A) and potentially other additional smaller-scale layers are identified only on the higher-resolution VSP data. The 3D industry seismic data set processed to preserve the relative true-amplitudes was used for attribute calculations and acoustic impedance inversion. The attribute maps defined areas of continuous reflectivity for horizons B and C and structural features disrupting them. Results from impedance inversion indicate that such continuous reflectivity around the wells is most likely attributable to gas hydrates. The middle gas hydrate occurrence (horizon B) covers an area of approximately 25 000m2. Horizon C, which marks the base of gas hydrate occurrence zone, extends over a larger area of approximately 120 000m2.

Investigating the influence of lithologic heterogeneity on gas hydrate formation and methane recycling at the base of the gas hydrate stability zone in channelized systems

Energy Technology Data Exchange (ETDEWEB)

Daigle, Hugh; Nole, Michael; Cook, Ann; Malinverno, Alberto

2017-12-14

In marine environments, gas hydrate preferentially accumulates in coarse-grained sediments. At the meso- to micro-scale, however, hydrate distribution in these coarse-grained units is often heterogeneous. We employ a methane hydrate reservoir simulator coupling heat and mass transfer as well as capillary effects to investigate how capillary controls on methane solubility affect gas and hydrate accumulations in reservoirs characterized by graded bedding and alternating sequences of coarse-grained sands and fine-grained silt and clay. Simulations bury a channelized reservoir unit encased in homogeneous, fine-grained material characterized by small pores (150 nm) and low permeability (~1 md in the absence of hydrate). Pore sizes within each reservoir bed between vary between coarse sand and fine silt. Sands have a median pore size of 35 microns and a lognormal pore size distribution. We also investigate how the amount of labile organic carbon (LOC) affects hydrate growth due to microbial methanogenesis within the sediments. In a diffusion-dominated system, methane movies into reservoir layers along spatial gradients in dissolved methane concentration. Hydrate grows in such a way as to minimize these concentration gradients by accumulating slower in finer-grained reservoir layers and faster in coarser-grained layers. Channelized, fining-upwards sediment bodies accumulate hydrate first along their outer surfaces and thence inward from top to bottom. If LOC is present in thin beds within the channel, higher saturations of hydrate will be distributed more homogeneously throughout the unit. When buried beneath the GHSZ, gas recycling can occur only if enough hydrate is present to form a connected gas phase upon dissociation. Simulations indicate that this is difficult to achieve for diffusion-dominated systems, especially those with thick GHSZs and/or small amounts of LOC. However, capillary-driven fracturing behavior may be more prevalent in settings with thick GHSZs.

Characterization of a lime-pozzolan plaster containing phase change material

International Nuclear Information System (INIS)

Pavlíková, Milena; Pavlík, Zbyšek; Trník, Anton; Pokorný, Jaroslav; Černý, Robert

2015-01-01

A PCM (Phase Change Material) modified lime-pozzolan plaster for improvement of thermal energy storage of building envelopes is studied in the paper. The investigated plaster is composed of lime hydrate, pozzolan admixture based on metakaolin and mudstone, silica sand, water and paraffin wax encapsulated in polymer capsule. The reference plaster without PCM application is studied as well. The analyzed materials are characterized by bulk density, matrix density, total open porosity, compressive strength and pore size distribution. The temperature of phase change, heat of fusion and crystallization are studied using DSC (Difference Scanning Calorimetry) analysis performed in air atmosphere. In order to get information on materials hygrothermal performance, determination of thermal and hygric properties is done in laboratory conditions. Experimental data reveal a substantial improvement of heat storage capacity of PCM-modified plaster as compared to the reference material without PCM

Feasibility of using phase change materials to control the heat of hydration in massive concrete structures.

Science.gov (United States)

Choi, Won-Chang; Khil, Bae-Soo; Chae, Young-Seok; Liang, Qi-Bo; Yun, Hyun-Do

2014-01-01

This paper presents experimental results that can be applied to select a possible phase change material (PCM), such as a latent heat material (LHM), to control the hydration heat in mass concrete structures. Five experimental tests (microconduction, simplified adiabatic temperature rise, heat, and compressive strength tests) were conducted to select the most desirable LHM out of seven types of inorganic PCM used in cement mortar and to determine the most suitable mix design. The results of these experimental tests were used to assess the feasibility of using PCM to reduce hydration heat in mass concrete that was examined. The experimental results show that cement mortar containing barium- [Ba(OH)2 · 8H2O] based PCM has the lowest amount of total hydration heat of the cement pastes. The barium-based PCM provides good latent heat properties that help to prevent volume change and microcracks caused by thermal stress in mass concrete.

Feasibility of Using Phase Change Materials to Control the Heat of Hydration in Massive Concrete Structures

Directory of Open Access Journals (Sweden)

Won-Chang Choi

2014-01-01

Full Text Available This paper presents experimental results that can be applied to select a possible phase change material (PCM, such as a latent heat material (LHM, to control the hydration heat in mass concrete structures. Five experimental tests (microconduction, simplified adiabatic temperature rise, heat, and compressive strength tests were conducted to select the most desirable LHM out of seven types of inorganic PCM used in cement mortar and to determine the most suitable mix design. The results of these experimental tests were used to assess the feasibility of using PCM to reduce hydration heat in mass concrete that was examined. The experimental results show that cement mortar containing barium- [Ba(OH2·8H2O] based PCM has the lowest amount of total hydration heat of the cement pastes. The barium-based PCM provides good latent heat properties that help to prevent volume change and microcracks caused by thermal stress in mass concrete.

In-Situ Sampling and Characterization of Naturally Occurring Marine Methane Hydrate Using the D/V JOIDES Resolution

Energy Technology Data Exchange (ETDEWEB)

Frank R. Rack

2006-09-20

Cooperative Agreement DE-FC26-01NT41329 between Joint Oceanographic Institutions and DOE-NETL was divided into two phases based on successive proposals and negotiated statements of work pertaining to activities to sample and characterize methane hydrates on ODP Leg 204 (Phase 1) and on IODP Expedition 311 (Phase 2). The Phase 1 Final Report was submitted to DOE-NETL in April 2004. This report is the Phase 2 Final Report to DOE-NETL. The primary objectives of Phase 2 were to sample and characterize methane hydrates using the systems and capabilities of the D/V JOIDES Resolution during IODP Expedition 311, to enable scientists the opportunity to establish the mass and distribution of naturally occurring gas and gas hydrate at all relevant spatial and temporal scales, and to contribute to the DOE methane hydrate research and development effort. The goal of the work was to provide expanded measurement capabilities on the JOIDES Resolution for a dedicated hydrate cruise to the Cascadia continental margin off Vancouver Island, British Columbia, Canada (IODP Expedition 311) so that hydrate deposits in this region would be well characterized and technology development continued for hydrate research. IODP Expedition 311 shipboard activities on the JOIDES Resolution began on August 28 and were concluded on October 28, 2005. The statement of work for this project included three primary tasks: (1) research management oversight, provided by JOI; (2) mobilization, deployment and demobilization of pressure coring and core logging systems, through a subcontract with Geotek Ltd.; and, (3) mobilization, deployment and demobilization of a refrigerated container van that will be used for degassing of the Pressure Core Sampler and density logging of these pressure cores, through a subcontract with the Texas A&M Research Foundation (TAMRF). Additional small tasks that arose during the course of the research were included under these three primary tasks in consultation with the DOE

Hydration study of limestone blended cement in the presence of hazardous wastes containing Cr(VI)

International Nuclear Information System (INIS)

Trezza, M.A.; Ferraiuelo, M.F.

2003-01-01

Considering the increasing use of limestone cement manufacture, the present paper tends to characterize limestone behavior in the presence of Cr(VI). The research reported herein provides information regarding the effect of Cr(VI) from industrial wastes in the limestone cement hydration. The cementitious materials were ordinary Portland cement, as reference, and limestone blended cement. The hydration and physicomechanical properties of cementitious materials and the influence of chromium at an early age were studied with X-ray diffraction (XRD), infrared spectroscopy (FTIR), conductimetric and mechanical tests. Portland cement pastes with the addition of Cr(VI) were examined and leaching behavior with respect to water and acid solution were investigated. This study indicates that Cr(VI) modifies the rate and the components obtained during the cement hydration

A Study on the quantification of hydration and the strength development mechanism of cementitious materials including amorphous phases by using XRD/Rietveld method

International Nuclear Information System (INIS)

Yamada, Kazuo; Hoshino, Seiichi; Hirao, Hiroshi; Yamashita, Hiroki

2008-01-01

X-ray diffraction (XRD)/Rietveld method was applied to measure the phase composition of cement. The quantative analysis concerning the progress of hydration was accomplished in an error of about the maximum 2-3% in spite of including amorphous materials such as blast furnace slag, fly ash, silica fume and C-S-H. The influence of the compressive strength on the lime stone fine powder mixture material was studied from the hydration analysis by Rietveld method. The two stages were observed in the strength development mechanism of cement; the hydration promotion of C 3 S in the early stage and the filling of cavities by carbonate hydrate for the longer term. It is useful to use various mixture materials for the formation of the resource recycling society and the durability improvement of concrete. (author)

Influence of aggregate and supplementary cementitious materials on the properties of hydrated lime (CL90s mortars

Directory of Open Access Journals (Sweden)

S. Pavía

2016-11-01

Full Text Available Hydrated lime is a historic material currently used in conservation. It hardens slowly by carbonation slowing construction however, supplementary cementitious materials accelerate hardening enhancing strength. Hydrated-lime mortars with rice husk ash–RHA-; ground granulated blastfurnace slag–GGBS- and increasing amounts of two aggregates were studied. Increasing aggregate lowered strength as interfacial zones proliferate; it lowered hygric properties and raised water demand. Aggregate content/composition didn’t affect the high water retention. For the higher aggregate contents (90 days, limestone mortars are c.20% stronger than silica mortars while the (1:1 silica sand mortars are 56% stronger in flexion. Additions increased strength with little impact on hygric properties. GGBS increased strength c.six times. RHA increased strength with little impact on hygric properties due to its great specific surface and high water-demand increasing porosity. GGBS and RHA properties ruling hydrate production and the kinetics of the pozzolanic reaction are considered partially responsible for the mortar property variation.

Synthesis and characterization of alanine boron hydrate for its use in thermal neutron dosimetry

International Nuclear Information System (INIS)

Yanez S, J.C.

1994-01-01

Alanine boron hydrate was synthesized for its possible use as intercomparison dosimeter for thermal neutron irradiation. The irradiations were performed in the Nuclear Reactor of the Nuclear Center of Mexico. The salt was prepared by reacting alanine and boric acid in a (1:1) stoichiometric ratio in neutral pH 7.5 aqueous solution and also in a basic pH 13 solution. The latter reaction was prepared with the addition of ammonia hydroxide (25%). Solutions were stirred and afterwards were let to evaporate. The obtained product in each reaction is a white solid. Dosimeters were prepared with the obtained reaction products and irradiated under thermal neutron flux of 5 x 10 7 n/cm 2 s. For 30 hours. The analysis of irradiated samples was made in a Variant E-15 Electron Paramagnetic Resonance spectrometer. The observed response of the samples prepared with the reaction product at the basic pH is approximately 50% higher than the neutral pH samples. In order to investigate the optimum signal enhancement samples were prepared in a basic pH medium in the following stoichiometric ratios: (1:0.5); (1:0.75); (1:1.25); (1:1.5) and (1:1.75). It was observed that the samples of the reaction (1:0.75) produced the higher response. The response was 2728% higher than the alanine only dosimeters. The reaction product was chemically characterized by X-ray diffraction, Nuclear Magnetic Resonance, Chromatography, Refractometry and Solubility tests. Results indicate that alanine boron hydrate is formed in basic media and in a stoichiometric ratio (1:0.75). The dosimetric characterization of alanine boron hydrate was performed, results are reported. It is concluded that alanine boron hydrate may be a good intercomparison dosimeter for thermal neutron irradiation. (Author)

Atomistic modeling of structure II gas hydrate mechanics: Compressibility and equations of state

Science.gov (United States)

Vlasic, Thomas M.; Servio, Phillip; Rey, Alejandro D.

2016-08-01

This work uses density functional theory (DFT) to investigate the poorly characterized structure II gas hydrates, for various guests (empty, propane, butane, ethane-methane, propane-methane), at the atomistic scale to determine key structure and mechanical properties such as equilibrium lattice volume and bulk modulus. Several equations of state (EOS) for solids (Murnaghan, Birch-Murnaghan, Vinet, Liu) were fitted to energy-volume curves resulting from structure optimization simulations. These EOS, which can be used to characterize the compressional behaviour of gas hydrates, were evaluated in terms of their robustness. The three-parameter Vinet EOS was found to perform just as well if not better than the four-parameter Liu EOS, over the pressure range in this study. As expected, the Murnaghan EOS proved to be the least robust. Furthermore, the equilibrium lattice volumes were found to increase with guest size, with double-guest hydrates showing a larger increase than single-guest hydrates, which has significant implications for the widely used van der Waals and Platteeuw thermodynamic model for gas hydrates. Also, hydrogen bonds prove to be the most likely factor contributing to the resistance of gas hydrates to compression; bulk modulus was found to increase linearly with hydrogen bond density, resulting in a relationship that could be used predictively to determine the bulk modulus of various structure II gas hydrates. Taken together, these results fill a long existing gap in the material chemical physics of these important clathrates.

Atomistic modeling of structure II gas hydrate mechanics: Compressibility and equations of state

Directory of Open Access Journals (Sweden)

Thomas M. Vlasic

2016-08-01

Full Text Available This work uses density functional theory (DFT to investigate the poorly characterized structure II gas hydrates, for various guests (empty, propane, butane, ethane-methane, propane-methane, at the atomistic scale to determine key structure and mechanical properties such as equilibrium lattice volume and bulk modulus. Several equations of state (EOS for solids (Murnaghan, Birch-Murnaghan, Vinet, Liu were fitted to energy-volume curves resulting from structure optimization simulations. These EOS, which can be used to characterize the compressional behaviour of gas hydrates, were evaluated in terms of their robustness. The three-parameter Vinet EOS was found to perform just as well if not better than the four-parameter Liu EOS, over the pressure range in this study. As expected, the Murnaghan EOS proved to be the least robust. Furthermore, the equilibrium lattice volumes were found to increase with guest size, with double-guest hydrates showing a larger increase than single-guest hydrates, which has significant implications for the widely used van der Waals and Platteeuw thermodynamic model for gas hydrates. Also, hydrogen bonds prove to be the most likely factor contributing to the resistance of gas hydrates to compression; bulk modulus was found to increase linearly with hydrogen bond density, resulting in a relationship that could be used predictively to determine the bulk modulus of various structure II gas hydrates. Taken together, these results fill a long existing gap in the material chemical physics of these important clathrates.

Atomistic modeling of structure II gas hydrate mechanics: Compressibility and equations of state

Energy Technology Data Exchange (ETDEWEB)

Vlasic, Thomas M.; Servio, Phillip; Rey, Alejandro D., E-mail: alejandro.rey@mcgill.ca [Department of Chemical Engineering, McGill University, Montreal H3A 0C5 (Canada)

2016-08-15

This work uses density functional theory (DFT) to investigate the poorly characterized structure II gas hydrates, for various guests (empty, propane, butane, ethane-methane, propane-methane), at the atomistic scale to determine key structure and mechanical properties such as equilibrium lattice volume and bulk modulus. Several equations of state (EOS) for solids (Murnaghan, Birch-Murnaghan, Vinet, Liu) were fitted to energy-volume curves resulting from structure optimization simulations. These EOS, which can be used to characterize the compressional behaviour of gas hydrates, were evaluated in terms of their robustness. The three-parameter Vinet EOS was found to perform just as well if not better than the four-parameter Liu EOS, over the pressure range in this study. As expected, the Murnaghan EOS proved to be the least robust. Furthermore, the equilibrium lattice volumes were found to increase with guest size, with double-guest hydrates showing a larger increase than single-guest hydrates, which has significant implications for the widely used van der Waals and Platteeuw thermodynamic model for gas hydrates. Also, hydrogen bonds prove to be the most likely factor contributing to the resistance of gas hydrates to compression; bulk modulus was found to increase linearly with hydrogen bond density, resulting in a relationship that could be used predictively to determine the bulk modulus of various structure II gas hydrates. Taken together, these results fill a long existing gap in the material chemical physics of these important clathrates.

Properties of calcium depleted hydrated cement paste: mineralogical characterization and cesium adsorption

International Nuclear Information System (INIS)

Babaahmadi, A.; Tang, L.; Zareen, A.

2015-01-01

Understanding the changes in adsorption properties of cementitious barriers and the effect on the release of radio-nuclides to the environment during the service life of the repository is of high importance. A major degradation scenario within safety assessment analysis of nuclear waste repositories is decalcification of cementitious materials due to long-term contact with groundwater. In order to decrease the uncertainty in the simulation of this process due to extrapolating short term data sets based on short term experimental analysis, acceleration methods enhancing the decalcification process can be used. However it is not yet completely proved that how different the properties of the aged samples through accelerated leaching is compared to the samples aged in natural ageing process. In this study the changes in cesium adsorption of the hydrated cement paste due to calcium depletion is taken in to consideration. The aged samples are prepared with application of an accelerating electro-chemical migration method. The mineralogical properties of decalcified specimens are characterized to demonstrate their comparability with naturally leached samples. The gradual effect of migration function on cementitious materials indicates a relatively homogenous leaching in cementitious specimens and a considerable increase in specific surface area due to the leaching of calcium. It is concluded that the aged samples having a larger surface area and less calcium and alkalis ions compared to pristine materials, exhibit a higher binding potential for Cs ions

Portland cement hydration and early setting of cement stone intended for efficient paving materials

Science.gov (United States)

Grishina, A.

2017-10-01

Due to the growth of load on automotive roads, modern transportation engineering is in need of efficient paving materials. Runways and most advanced highways require Portland cement concretes. This makes important the studies directed to improvement of binders for such concretes. In the present work some peculiarities of the process of Portland cement hydration and early setting of cement stone with barium hydrosilicate sol were examined. It was found that the admixture of said sol leads to a shift in the induction period to later times without significant change in its duration. The admixture of a modifier with nanoscale barium hydrosilicates increases the degree of hydration of the cement clinker minerals and changes the phase composition of the hydration products; in particular, the content of portlandite and tricalcium silicate decreases, while the amount of ettringite increases. Changes in the hydration processes of Portland cement and early setting of cement stone that are caused by the nanoscale barium hydrosilicates, allow to forecast positive technological effects both at the stage of manufacturing and at the stage of operation. In particular, the formwork age can be reduced, turnover of molds can be increased, formation of secondary ettringite and corrosion of the first type can be eliminated.

Ductile flow of methane hydrate

Science.gov (United States)

Durham, W.B.; Stern, L.A.; Kirby, S.H.

2003-01-01

Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

Advanced Nanoscale Characterization of Cement Based Materials Using X-Ray Synchrotron Radiation: A Review

KAUST Repository

Chae, Sejung R.

2013-05-22

We report various synchrotron radiation laboratory based techniques used to characterize cement based materials in nanometer scale. High resolution X-ray transmission imaging combined with a rotational axis allows for rendering of samples in three dimensions revealing volumetric details. Scanning transmission X-ray microscope combines high spatial resolution imaging with high spectral resolution of the incident beam to reveal X-ray absorption near edge structure variations in the material nanostructure. Microdiffraction scans the surface of a sample to map its high order reflection or crystallographic variations with a micron-sized incident beam. High pressure X-ray diffraction measures compressibility of pure phase materials. Unique results of studies using the above tools are discussed-a study of pores, connectivity, and morphology of a 2,000 year old concrete using nanotomography; detection of localized and varying silicate chain depolymerization in Al-substituted tobermorite, and quantification of monosulfate distribution in tricalcium aluminate hydration using scanning transmission X-ray microscopy; detection and mapping of hydration products in high volume fly ash paste using microdiffraction; and determination of mechanical properties of various AFm phases using high pressure X-ray diffraction. © 2013 The Author(s).

Magnetic susceptibility and magnetic resonance measurements of the moisture content and hydration condition of a magnetic mixture material

International Nuclear Information System (INIS)

Tsukada, K.; Kusaka, T.; Saari, M. M.; Takagi, R.; Sakai, K.; Kiwa, T.; Bito, Y.

2014-01-01

We developed a magnetic measurement method to measure the moisture content and hydration condition of mortar as a magnetic mixture material. Mortar is a mixture of Portland cement, sand, and water, and these materials exhibit different magnetic properties. The magnetization–magnetic field curves of these components and of mortars with different moisture contents were measured, using a specially developed high-temperature-superconductor superconducting quantum interference device. Using the differences in magnetic characteristics, the moisture content of mortar was measured at the ferromagnetic saturation region over 250 mT. A correlation between magnetic susceptibility and moisture content was successfully established. After Portland cement and water are mixed, hydration begins. At the early stage of the hydration/gel, magnetization strength increased over time. To investigate the magnetization change, we measured the distribution between bound and free water in the mortar in the early stage by magnetic resonance imaging (MRI). The MRI results suggest that the amount of free water in mortar correlates with the change in magnetic susceptibility

Application of empirical hydration distribution functions around polar atoms for assessing hydration structures of proteins

International Nuclear Information System (INIS)

Matsuoka, Daisuke; Nakasako, Masayoshi

2013-01-01

Highlights: ► Empirical distribution functions of water molecules in protein hydration are made. ► The functions measure how hydrogen-bond geometry in hydration deviate from ideal. ► The functions assess experimentally identified hydration structures of protein. - Abstract: To quantitatively characterize hydrogen-bond geometry in local hydration structures of proteins, we constructed a set of empirical hydration distribution functions (EHDFs) around polar protein atoms in the main and side chains of 11 types of hydrophilic amino acids (D. Matsuoka, M. Nakasako, Journal of Physical Chemistry B 113 (2009) 11274). The functions are the ensemble average of possible hydration patterns around the polar atoms, and describe the anisotropic deviations from ideal hydrogen bond geometry. In addition, we defined probability distribution function of hydration water molecules (PDFH) over the hydrophilic surface of a protein as the sum of EHDFs of solvent accessible polar protein atoms. The functions envelop most of hydration sites identified in crystal structures of proteins (D. Matsuoka, M. Nakasako, Journal of Physical Chemistry B 114 (2010) 4652). Here we propose the application of EHDFs and PDFHs for assessing crystallographically identified hydration structures of proteins. First, hydration water molecules are classified with respect to the geometry in hydrogen bonds in referring EHDFs. Difference Fourier electron density map weighted by PDFH of protein is proposed to identify easily density peaks as candidates of hydration water molecules. A computer program implementing those ideas was developed and used for assessing hydration structures of proteins

Hydration behaviors of calcium silicate-based biomaterials.

Science.gov (United States)

Lee, Yuan-Ling; Wang, Wen-Hsi; Lin, Feng-Huie; Lin, Chun-Pin

2017-06-01

Calcium silicate (CS)-based biomaterials, such as mineral trioxide aggregate (MTA), have become the most popular and convincing material used in restorative endodontic treatments. However, the commercially available CS-based biomaterials all contain different minor additives, which may affect their hydration behaviors and material properties. The purpose of this study was to evaluate the hydration behavior of CS-based biomaterials with/without minor additives. A novel CS-based biomaterial with a simplified composition, without mineral oxides as minor additives, was produced. The characteristics of this biomaterial during hydration were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrometry. The hydration behaviors of commercially available gray and white MTAs with mineral oxide as minor additives were also evaluated for reference. For all three test materials, the XRD analysis revealed similar diffraction patterns after hydration, but MTAs presented a significant decrease in the intensities of Bi 2 O 3 -related peaks. SEM results demonstrated similar porous microstructures with some hexagonal and facetted crystals on the outer surfaces. In addition, compared to CS with a simplified composition, the FTIR plot indicated that hydrated MTAs with mineral oxides were better for the polymerization of calcium silicate hydrate (CSH), presenting Si-O band shifting to higher wave numbers, and contained more water crystals within CSH, presenting sharper bands for O-H bending. Mineral oxides might not result in significant changes in the crystal phases or microstructures during the hydration of CS-based biomaterials, but these compounds affected the hydration behavior at the molecular level. Copyright © 2016. Published by Elsevier B.V.

Gas hydrate cool storage system

Science.gov (United States)

Ternes, M.P.; Kedl, R.J.

1984-09-12

The invention presented relates to the development of a process utilizing a gas hydrate as a cool storage medium for alleviating electric load demands during peak usage periods. Several objectives of the invention are mentioned concerning the formation of the gas hydrate as storage material in a thermal energy storage system within a heat pump cycle system. The gas hydrate was formed using a refrigerant in water and an example with R-12 refrigerant is included. (BCS)

Hydration induced material transfer in membranes of osmotic pump tablets measured by synchrotron radiation based FTIR.

Science.gov (United States)

Wu, Li; Yin, Xianzhen; Guo, Zhen; Tong, Yajun; Feng, Jing; York, Peter; Xiao, Tiqiao; Chen, Min; Gu, Jingkai; Zhang, Jiwen

2016-03-10

Osmotic pump tablets are reliable oral controlled drug delivery systems based on their semipermeable membrane coating. This research used synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy and imaging to investigate the hydration induced material transfer in the membranes of osmotic pump tablets. SR-FTIR was applied to record and map the chemical information of a micro-region of the membranes, composed of cellulose acetate (CA, as the water insoluble matrix) and polyethylene glycol (PEG, as the soluble pore forming agent and plasticizing agent). The microstructure and chemical change of membranes hydrated for 0, 5, 10 and 30min were measured using SR-FTIR, combined with scanning electronic microscopy and atom force microscopy. The SR-FTIR microspectroscopy results indicated that there was a major change at the absorption range of 2700-3100cm(-1) in the membranes after different periods of hydration time. The absorption bands at 2870-2880cm(-1) and 2950-2960cm(-1) were assigned to represent CA and PEG, respectively. The chemical group signal distribution illustrated by the ratio of PEG to CA demonstrated that the trigger of drug release in the preliminary stage was due to the rapid transfer of PEG into liquid medium with a sharp decrease of PEG in the membranes. The SR-FTIR mapping results have demonstrated the hydration induced material transfer in the membranes of osmotic pump tablets and enabled reassessment of the drug release mechanism of membrane controlled osmotic pump systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of blends bauxite-calcination-method red mud with other industrial wastes as a cementitious material: Properties and hydration characteristics

International Nuclear Information System (INIS)

Zhang Na; Liu Xiaoming; Sun Henghu; Li Longtu

2011-01-01

Red mud is generated from alumina production, and its disposal is currently a worldwide problem. In China, large quantities of red mud derived from bauxite calcination method are being discharged annually, and its utilization has been an urgent topic. This experimental research was to evaluate the feasibility of blends red mud derived from bauxite calcination method with other industrial wastes for use as a cementitious material. The developed cementitious material containing 30% of the bauxite-calcination-method red mud possessed compressive strength properties at a level similar to normal Portland cement, in the range of 45.3-49.5 MPa. Best compressive strength values were demonstrated by the specimen RSFC2 containing 30% bauxite-calcination-method red mud, 21% blast-furnace slag, 10% fly ash, 30% clinker, 8% gypsum and 1% compound agent. The mechanical and physical properties confirm the usefulness of RSFC2. The hydration characteristics of RSFC2 were characterized by XRD, FTIR, 27 Al MAS-NMR and SEM. As predominant hydration products, ettringite and amorphous C-S-H gel are principally responsible for the strength development of RSFC2. Comparing with the traditional production for ordinary Portland cement, this green technology is easier to be implemented and energy saving. This paper provides a key solution to effectively utilize bauxite-calcination-method red mud.

Elastic wave speeds and moduli in polycrystalline ice Ih, si methane hydrate, and sll methane-ethane hydrate

Science.gov (United States)

Helgerud, M.B.; Waite, W.F.; Kirby, S.H.; Nur, A.

2009-01-01

We used ultrasonic pulse transmission to measure compressional, P, and shear, S, wave speeds in laboratory-formed polycrystalline ice Ih, si methane hydrate, and sll methane-ethane hydrate. From the wave speed's linear dependence on temperature and pressure and from the sample's calculated density, we derived expressions for bulk, shear, and compressional wave moduli and Poisson's ratio from -20 to 15??C and 22.4 to 32.8 MPa for ice Ih, -20 to 15??C and 30.5 to 97.7 MPa for si methane hydrate, and -20 to 10??C and 30.5 to 91.6 MPa for sll methane-ethane hydrate. All three materials had comparable P and S wave speeds and decreasing shear wave speeds with increasing applied pressure. Each material also showed evidence of rapid intergranular bonding, with a corresponding increase in wave speed, in response to pauses in sample deformation. There were also key differences. Resistance to uniaxial compaction, indicated by the pressure required to compact initially porous samples, was significantly lower for ice Ih than for either hydrate. The ice Ih shear modulus decreased with increasing pressure, in contrast to the increase measured in both hydrates ?? 2009.

Hydration of swelling clays: multi-scale sequence of hydration and determination of macroscopic energies from microscopic properties; Hydratation des argiles gonflantes: sequence d'hydratation multi-echelle determination des energies macroscopiques a partir des proprietes microscopiques

Energy Technology Data Exchange (ETDEWEB)

Salles, F

2006-10-15

Smectites have interesting properties which make them potential candidates for engineered barriers in deep geological nuclear waste repository: low permeability, swelling and cations retention. The subject of this thesis consists in the determination of the relationship between hydration properties, swelling properties and cations mobility in relation with confinement properties of clayey materials. The aim is to understand and to predict the behaviour of water in smectites, following two research orientations: the mechanistic aspects and the energetic aspects of the hydration of smectites. We worked on the Na-Ca montmorillonite contained in the MX80 bentonite, with the exchanged homo ionic structure (saturated with alkaline cations and calcium cations). The approach crosses the various scales (microscopic, mesoscopic and macroscopic) and implied the study of the various components of the system (layer-cation-water), by using original experimental methods (thermo-poro-metry and electric conductivity for various relative humidities (RH) and electrostatic calculations. Initially, the dry state is defined by SCTA (scanning calorimetry thermal analysis). Then a classical characterization of the smectite porosity for the dry state is carried out using mercury intrusion and nitrogen adsorption. We evidenced the existence of a meso-porosity which radius varies from 2 to 10 nm depending on the compensating cation. The thermo-poro-metry and conductivity experiments performed at various hydration states made it possible to follow the increase in the pore sizes and the cations mobility as a function of the hydration state. We highlight in particular the existence of an osmotic mesoscopic swelling for low RH (approximately 50-60%RH for Li and Na). By combining the results of thermo-poro-metry, X-ray diffraction and electric conductivity, we are able to propose a complete hydration sequence for each cation, showing the crucial role of the compensating cation in the hydration of

The anomalous halogen bonding interactions between chlorine and bromine with water in clathrate hydrates.

Science.gov (United States)

Dureckova, Hana; Woo, Tom K; Udachin, Konstantin A; Ripmeester, John A; Alavi, Saman

2017-10-13

Clathrate hydrate phases of Cl 2 and Br 2 guest molecules have been known for about 200 years. The crystal structure of these phases was recently re-determined with high accuracy by single crystal X-ray diffraction. In these structures, the water oxygen-halogen atom distances are determined to be shorter than the sum of the van der Waals radii, which indicates the action of some type of non-covalent interaction between the dihalogens and water molecules. Given that in the hydrate phases both lone pairs of each water oxygen atom are engaged in hydrogen bonding with other water molecules of the lattice, the nature of the oxygen-halogen interactions may not be the standard halogen bonds characterized recently in the solid state materials and enzyme-substrate compounds. The nature of the halogen-water interactions for the Cl 2 and Br 2 molecules in two isolated clathrate hydrate cages has recently been studied with ab initio calculations and Natural Bond Order analysis (Ochoa-Resendiz et al. J. Chem. Phys. 2016, 145, 161104). Here we present the results of ab initio calculations and natural localized molecular orbital analysis for Cl 2 and Br 2 guests in all cage types observed in the cubic structure I and tetragonal structure I clathrate hydrates to characterize the orbital interactions between the dihalogen guests and water. Calculations with isolated cages and cages with one shell of coordinating molecules are considered. The computational analysis is used to understand the nature of the halogen bonding in these materials and to interpret the guest positions in the hydrate cages obtained from the X-ray crystal structures.

Hydration dependent dynamics in RNA

International Nuclear Information System (INIS)

Olsen, Greg L.; Bardaro, Michael F.; Echodu, Dorothy C.; Drobny, Gary P.; Varani, Gabriele

2009-01-01

The essential role played by local and collective motions in RNA function has led to a growing interest in the characterization of RNA dynamics. Recent investigations have revealed that even relatively simple RNAs experience complex motions over multiple time scales covering the entire ms-ps motional range. In this work, we use deuterium solid-state NMR to systematically investigate motions in HIV-1 TAR RNA as a function of hydration. We probe dynamics at three uridine residues in different structural environments ranging from helical to completely unrestrained. We observe distinct and substantial changes in 2 H solid-state relaxation times and lineshapes at each site as hydration levels increase. By comparing solid-state and solution state 13 C relaxation measurements, we establish that ns-μs motions that may be indicative of collective dynamics suddenly arise in the RNA as hydration reaches a critical point coincident with the onset of bulk hydration. Beyond that point, we observe smaller changes in relaxation rates and lineshapes in these highly hydrated solid samples, compared to the dramatic activation of motion occurring at moderate hydration

Research opportunities in salt hydrates for thermal energy storage

Science.gov (United States)

Braunstein, J.

1983-11-01

The state of the art of salt hydrates as phase change materials for low temperature thermal energy storage is reviewed. Phase equilibria, nucleation behavior and melting kinetics of the commonly used hydrate are summarized. The development of efficient, reliable inexpensive systems based on phase change materials, especially salt hydrates for the storage (and retrieval) of thermal energy for residential heating is outlined. The use of phase change material thermal energy storage systems is not yet widespread. Additional basic research is needed in the areas of crystallization and melting kinetics, prediction of phase behavior in ternary systems, thermal diffusion in salt hydrate systems, and in the physical properties pertinent to nonequilibrium and equilibrium transformations in these systems.

Exogenous origin of hydration on asteroid (16) Psyche: the role of hydrated asteroid families

Science.gov (United States)

Avdellidou, C.; Delbo', M.; Fienga, A.

2018-04-01

Asteroid (16) Psyche, which for a long time was the largest M-type with no detection of hydration features in its spectrum, was recently discovered to have a weak 3-μm band and thus it was eventually added to the group of hydrated asteroids. Its relatively high density, in combination with the high radar albedo, led researchers to classify the asteroid as a metallic object. It is believed that it is possibly a core of a differentiated body, a remnant of `hit-and-run' collisions. The detection of hydration is, in principle, inconsistent with a pure metallic origin for this body. Here, we consider the scenario in which the hydration on its surface is exogenous and was delivered by hydrated impactors. We show that impacting asteroids that belong to families whose members have the 3-μm band can deliver hydrated material to Psyche. We developed a collisional model with which we test all dark carbonaceous asteroid families, which contain hydrated members. We find that the major source of hydrated impactors is the family of Themis, with a total implanted mass on Psyche of the order of ˜1014 kg. However, the hydrated fraction could be only a few per cent of the implanted mass, as the water content in carbonaceous chondrite meteorites, the best analogue for the Themis asteroid family, is typically a few per cent of their mass.

Solid-state 27Al and 29Si NMR characterization of hydrates formed in calcium aluminate-silica fume mixtures

International Nuclear Information System (INIS)

Pena, P.; Rivas Mercury, J.M.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

2008-01-01

Partially deuterated Ca 3 Al 2 (SiO 4 ) y (OH) 12-4y -Al(OH) 3 mixtures, prepared by hydration of Ca 3 Al 2 O 6 (C 3 A), Ca 12 Al 14 O 33 (C 12 A 7 ) and CaAl 2 O 4 (CA) phases in the presence of silica fume, have been characterized by 29 Si and 27 Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies. NMR spectroscopy was used to characterize anhydrous and fully hydrated samples. In hydrated compounds, Ca 3 Al 2 (OH) 12 and Al(OH) 3 phases were detected. From the quantitative analysis of 27 Al NMR signals, the Al(OH) 3 /Ca 3 Al 2 (OH) 12 ratio was deduced. The incorporation of Si into the katoite structure, Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x , was followed by 27 Al and 29 Si NMR spectroscopies. Si/OH ratios were determined from the quantitative analysis of 27 Al MAS-NMR components associated with Al(OH) 6 and Al(OSi)(OH) 5 environments. The 29 Si NMR spectroscopy was also used to quantify the unreacted silica and amorphous calcium aluminosilicate hydrates formed, C-S-H and C-A-S-H for short. From 29 Si NMR spectra, the amount of Si incorporated into different phases was estimated. Si and Al concentrations, deduced by NMR, transmission electron microscopy, energy dispersive spectrometry, and Rietveld analysis of both X-ray and neutron data, indicate that only a part of available Si is incorporated in katoite structures. - Graphical abstract: Transmission electron micrograph of CaAl 2 O 4 -microsilica mixture hydrated at 90 deg. C for 31 days showing a cubic Ca 3 Al 2.0±0.2 (SiO 4 ) 0.9±0.2 (OH) 1.8 crystal surrounded by unreacted amorphous silica spheres

Predictive Mechanical Characterization of Macro-Molecular Material Chemistry Structures of Cement Paste at Nano Scale - Two-phase Macro-Molecular Structures of Calcium Silicate Hydrate, Tri-Calcium Silicate, Di-Calcium Silicate and Calcium Hydroxide

Science.gov (United States)

Padilla Espinosa, Ingrid Marcela

Concrete is a hierarchical composite material with a random structure over a wide range of length scales. At submicron length scale the main component of concrete is cement paste, formed by the reaction of Portland cement clinkers and water. Cement paste acts as a binding matrix for the other components and is responsible for the strength of concrete. Cement paste microstructure contains voids, hydrated and unhydrated cement phases. The main crystalline phases of unhydrated cement are tri-calcium silicate (C3S) and di-calcium silicate (C2S), and of hydrated cement are calcium silicate hydrate (CSH) and calcium hydroxide (CH). Although efforts have been made to comprehend the chemical and physical nature of cement paste, studies at molecular level have primarily been focused on individual components. Present research focuses on the development of a method to model, at molecular level, and analysis of the two-phase combination of hydrated and unhydrated phases of cement paste as macromolecular systems. Computational molecular modeling could help in understanding the influence of the phase interactions on the material properties, and mechanical performance of cement paste. Present work also strives to create a framework for molecular level models suitable for potential better comparisons with low length scale experimental methods, in which the sizes of the samples involve the mixture of different hydrated and unhydrated crystalline phases of cement paste. Two approaches based on two-phase cement paste macromolecular structures, one involving admixed molecular phases, and the second involving cluster of two molecular phases are investigated. The mechanical properties of two-phase macromolecular systems of cement paste consisting of key hydrated phase CSH and unhydrated phases C3S or C2S, as well as CSH with the second hydrated phase CH were calculated. It was found that these cement paste two-phase macromolecular systems predicted an isotropic material behavior. Also

Hydration Properties of Ground Granulated Blast-Furnace Slag (GGBS Under Different Hydration Environments

Directory of Open Access Journals (Sweden)

Shuhua LIU

2017-02-01

Full Text Available The hydration properties of various cementitious materials containing Ground Granulated Blast-furnace Slag (GGBS, two alkali-activated slag cements (AAS-1 and AAS-2 in which sodium silicate and sodium hydroxide act as alkaline activators respectively, supersulfated cement (SSC and slag Portland cement(PSC, are compared with ordinary Portland cement (OPC to investigate the effect of activating environment on the hydration properties in this study by determining the compressive strength of the pastes, the hydration heat of binders within 96 hours, and the hydration products at age of 28 days. The results show that C-S-H gels are the main hydrated products for all cementitious systems containing GGBS. Ca(OH2 is the hydration products of OPC and PSC paste. However, ettringite and gypsum crystals instead of Ca(OH2 are detected in SSC paste. Additionally, tobermorite, a crystalline C-S-H, and calcite are hydrated products in AAS-1. Tobermorite, cowlesite and calcite are hydrated products of AAS-2 as well. Based on strength results, AAS-1 paste exhibits the highest compressive strength followed by POC, PSC, SSC in order at all testing ages and AAS-2 give the lowest compressive strength except for the early age at 3 days, which is higher than SSC but still lower than PSC. From hydration heat analysis, alkalinity in the reaction solution is a vital factor influencing the initial hydration rate and the initial hydration rate from higher to lower is AAS-2, AAS-1, OPC, PSC and SSC. Although AAS possesses a faster reaction rate in the initial hours, cumulative hydration heat of AAS is comparably lower than that of OPC, but higher than those of PSC and SSC in turn, which indicates that the hydration heat of clinkers is much higher than that of slag.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.14934

Seismic Characterization of the Terrebonne Mini-basin, a Hydrate Rich Depositional System in the Gulf of Mexico

Science.gov (United States)

Dafov, L. N.; Eze, P. C.; Haines, S. S.; Graham, S. A.; McHargue, T.; Hosford Scheirer, A.

2017-12-01

Natural gas bearing hydrates are a focus of research as a potential source of energy and carbon storage because they occur globally in permafrost regions and marine sediment along every continent. This study focuses on the structural and stratigraphic architecture of the Terrebonne mini-basin, northwest Walker Ridge, Gulf of Mexico, to characterize the depositional architecture and to describe possible migration pathways for petroleum. Questions addressed include: a) continuity of sand layers b) effects of faulting and c) ponding versus fill and spill. To address these questions, seven of forty-two high resolution USGS 2D seismic lines were interpreted and then verified with WesternGeco 3D seismic data, yielding three qualitative models for the depositional environment of hydrate-bearing sand intervals. Deeper hydrate-bearing sand reservoirs were deposited as sheet-like turbidite lobes. Two shallower hydrate-bearing intervals display two possible depositional systems which form reservoirs- 1) sandy to muddy channel sealed laterally by muddy levees with associated sandy crevasse splays, and 2) ponded sandy lobes cut by channels filled with sand lags and mud. Additional observations in the 2D seismic include mass transport deposits and possible contourites. Salt movement facilitated mini-basin formation which was then ponded by sediment and followed by episodes of fill-and-spill and erosion. These seismic interpretations indicate periodic salt uplift. Overturn of salt along the northwestern edge of the basin resulted in thrust faults. The faults and erosional surfaces act as seals to reservoirs. The greatest volume of sandy reservoir potential occurs in sheet-like turbidite lobes with high lateral continuity, which facilitates updip migration of deep-sourced thermogenic gas along bedding surfaces. Channel levees serve as lateral seals to gas hydrate reservoirs, whereas faults, erosional surfaces, and shales provide vertical seals. Characterization of the Terrebonne

Experimental Determination of Refractive Index of Gas Hydrates

DEFF Research Database (Denmark)

Bylov, Martin; Rasmussen, Peter

1997-01-01

. For methane hydrate (structure I) the refractive index was found to be 1.346 and for natural gas hydrate (structure II) it was found to be 1.350. The measurements further suggest that the gas hydrate growth rate increases if the water has formed hydrates before. The induction time, on the other hand, seems......The refractive indexes of methane hydrate and natural gas hydrate have been experimentally determined. The refractive indexes were determined in an indirect manner making use of the fact that two non-absorbing materials will have the same refractive index if they cannot be distinguished visually...

Hydration of swelling clays: multi-scale sequence of hydration and determination of macroscopic energies from microscopic properties

International Nuclear Information System (INIS)

Salles, F.

2006-10-01

Smectites have interesting properties which make them potential candidates for engineered barriers in deep geological nuclear waste repository: low permeability, swelling and cations retention. The subject of this thesis consists in the determination of the relationship between hydration properties, swelling properties and cations mobility in relation with confinement properties of clayey materials. The aim is to understand and to predict the behaviour of water in smectites, following two research orientations: the mechanistic aspects and the energetic aspects of the hydration of smectites. We worked on the Na-Ca montmorillonite contained in the MX80 bentonite, with the exchanged homo ionic structure (saturated with alkaline cations and calcium cations). The approach crosses the various scales (microscopic, mesoscopic and macroscopic) and implied the study of the various components of the system (layer-cation-water), by using original experimental methods (thermo-poro-metry and electric conductivity for various relative humidities (RH) and electrostatic calculations. Initially, the dry state is defined by SCTA (scanning calorimetry thermal analysis). Then a classical characterization of the smectite porosity for the dry state is carried out using mercury intrusion and nitrogen adsorption. We evidenced the existence of a meso-porosity which radius varies from 2 to 10 nm depending on the compensating cation. The thermo-poro-metry and conductivity experiments performed at various hydration states made it possible to follow the increase in the pore sizes and the cations mobility as a function of the hydration state. We highlight in particular the existence of an osmotic mesoscopic swelling for low RH (approximately 50-60%RH for Li and Na). By combining the results of thermo-poro-metry, X-ray diffraction and electric conductivity, we are able to propose a complete hydration sequence for each cation, showing the crucial role of the compensating cation in the hydration of

Determining the mechanism and parameters of hydrate formation and loss in glucose.

Science.gov (United States)

Scholl, Sarah K; Schmidt, Shelly J

2014-11-01

Water-solid interactions are known to play a major role in the chemical and physical stability of food materials. Despite its extensive use throughout the food industry, the mechanism and parameters of hydrate formation and loss in glucose are not well characterized. Hydrate formation in alpha-anhydrous glucose (α-AG) and hydrate loss in glucose monohydrate (GM) were studied under equilibrium conditions at various relative humidity (RH) values using saturated salt slurries for 1 y. The mechanism of hydrate formation and hydrate loss were determined through mathematical modeling of Dynamic Vapor Sorption data and Raman spectroscopy was used to confirm the mechanisms. The critical temperature for hydrate loss in GM was determined using thermogravimetric analysis (TGA). The moisture sorption profiles of α-AG and GM were also studied under dynamic conditions using an AquaSorp Isotherm Generator. Hydrate formation was observed at and above 68% RH at 25 °C and the conversion of α-AG to GM can best be described as following a nucleation mechanism, however, diffusion and/or geometric contraction mechanisms were also observed by Raman spectroscopy subsequent to the coalescence of initial nucleation sites. Hydrate loss was observed to occur at and below 11% RH at 25 °C during RH storage and at 70 °C during TGA. The conversion of GM to α-AG follows nucleation and diffusion mechanisms. Hydrate formation was evident under dynamic conditions in α-AG and GM prior to deliquescence. This research is the first to report hydrate formation and loss parameters for crystalline α-AG and GM during extended storage at 25 ˚C. © 2014 Institute of Food Technologists®

Detection and Production of Methane Hydrate

Energy Technology Data Exchange (ETDEWEB)

George Hirasaki; Walter Chapman; Gerald Dickens; Colin Zelt; Brandon Dugan; Kishore Mohanty; Priyank Jaiswal

2011-12-31

This project seeks to understand regional differences in gas hydrate systems from the perspective of as an energy resource, geohazard, and long-term climate influence. Specifically, the effort will: (1) collect data and conceptual models that targets causes of gas hydrate variance, (2) construct numerical models that explain and predict regional-scale gas hydrate differences in 2-dimensions with minimal 'free parameters', (3) simulate hydrocarbon production from various gas hydrate systems to establish promising resource characteristics, (4) perturb different gas hydrate systems to assess potential impacts of hot fluids on seafloor stability and well stability, and (5) develop geophysical approaches that enable remote quantification of gas hydrate heterogeneities so that they can be characterized with minimal costly drilling. Our integrated program takes advantage of the fact that we have a close working team comprised of experts in distinct disciplines. The expected outcomes of this project are improved exploration and production technology for production of natural gas from methane hydrates and improved safety through understanding of seafloor and well bore stability in the presence of hydrates. The scope of this project was to more fully characterize, understand, and appreciate fundamental differences in the amount and distribution of gas hydrate and how this would affect the production potential of a hydrate accumulation in the marine environment. The effort combines existing information from locations in the ocean that are dominated by low permeability sediments with small amounts of high permeability sediments, one permafrost location where extensive hydrates exist in reservoir quality rocks and other locations deemed by mutual agreement of DOE and Rice to be appropriate. The initial ocean locations were Blake Ridge, Hydrate Ridge, Peru Margin and GOM. The permafrost location was Mallik. Although the ultimate goal of the project was to understand

Sedimentological Characterization of a Deepwater Methane Hydrate Reservoir in Green Canyon 955, Northern Gulf of Mexico

Science.gov (United States)

Meazell, K.; Flemings, P. B.

2017-12-01

Grain size is a controlling factor of hydrate saturation within a Pleistocene channel-levee system investigated by the UT-GOM2-1 expedition within the deepwater northern Gulf of Mexico. Laser diffraction and settling experiments conducted on sediments from 413-440 meters below the seafloor reveal the presence of two interbedded lithologic units, identified as a silty sand and a clayey silt, according Shepard's classification system. The sand-rich lithofacies has low density and high p-wave velocity, suggesting a high degree of hydrate saturation. Conversely, the clay and silt dominated lithofacies is characterized by a higher density and low p-wave velocity, suggesting low hydrate saturation. The sand-rich lithofacies is well-sorted and displays abundant ripple lamination, indicative of deposition within a high-energy environment. The clayey-silt is poorly-sorted and lacks sedimentary structures. The two lithofacies are interbedded throughout the reservoir unit; however, the relative abundance of the sand-rich lithofacies increases with depth, suggesting a potential decrease in flow energy or sediment flux over time, resulting in the most favorable reservoir properties near the base of the unit.

Use of X-ray diffraction to quantify amorphous supplementary cementitious materials in anhydrous and hydrated blended cements

International Nuclear Information System (INIS)

Snellings, R.; Salze, A.; Scrivener, K.L.

2014-01-01

The content of individual amorphous supplementary cementitious materials (SCMs) in anhydrous and hydrated blended cements was quantified by the PONKCS [1] X-ray diffraction (XRD) method. The analytical precision and accuracy of the method were assessed through comparison to a series of mixes of known phase composition and of increasing complexity. A 2σ precision smaller than 2–3 wt.% and an accuracy better than 2 wt.% were achieved for SCMs in mixes with quartz, anhydrous Portland cement, and hydrated Portland cement. The extent of reaction of SCMs in hydrating binders measured by XRD was 1) internally consistent as confirmed through the standard addition method and 2) showed a linear correlation to the cumulative heat release as measured independently by isothermal conduction calorimetry. The advantages, limitations and applicability of the method are discussed with reference to existing methods that measure the degree of reaction of SCMs in blended cements

Characterization of gas hydrate distribution using conventional 3D seismic data in the Pearl River Mouth Basin, South China Sea

Science.gov (United States)

Wang, Xiujuan; Qiang, Jin; Collett, Timothy S.; Shi, Hesheng; Yang, Shengxiong; Yan, Chengzhi; Li, Yuanping; Wang, Zhenzhen; Chen, Duanxin

2016-01-01

A new 3D seismic reflection data volume acquired in 2012 has allowed for the detailed mapping and characterization of gas hydrate distribution in the Pearl River Mouth Basin in the South China Sea. Previous studies of core and logging data showed that gas hydrate occurrence at high concentrations is controlled by the presence of relatively coarse-grained sediment and the upward migration of thermogenic gas from the deeper sediment section into the overlying gas hydrate stability zone (BGHSZ); however, the spatial distribution of the gas hydrate remains poorly defined. We used a constrained sparse spike inversion technique to generate acoustic-impedance images of the hydrate-bearing sedimentary section from the newly acquired 3D seismic data volume. High-amplitude reflections just above the bottom-simulating reflectors (BSRs) were interpreted to be associated with the accumulation of gas hydrate with elevated saturations. Enhanced seismic reflections below the BSRs were interpreted to indicate the presence of free gas. The base of the BGHSZ was established using the occurrence of BSRs. In areas absent of well-developed BSRs, the BGHSZ was calculated from a model using the inverted P-wave velocity and subsurface temperature data. Seismic attributes were also extracted along the BGHSZ that indicate variations reservoir properties and inferred hydrocarbon accumulations at each site. Gas hydrate saturations estimated from the inversion of acoustic impedance of conventional 3D seismic data, along with well-log-derived rock-physics models were also used to estimate gas hydrate saturations. Our analysis determined that the gas hydrate petroleum system varies significantly across the Pearl River Mouth Basin and that variability in sedimentary properties as a product of depositional processes and the upward migration of gas from deeper thermogenic sources control the distribution of gas hydrates in this basin.

Coupled numerical modeling of gas hydrates bearing sediments from laboratory to field-scale conditions

Science.gov (United States)

Sanchez, M. J.; Santamarina, C.; Gai, X., Sr.; Teymouri, M., Sr.

2017-12-01

Stability and behavior of Hydrate Bearing Sediments (HBS) are characterized by the metastable character of the gas hydrate structure which strongly depends on thermo-hydro-chemo-mechanical (THCM) actions. Hydrate formation, dissociation and methane production from hydrate bearing sediments are coupled THCM processes that involve, amongst other, exothermic formation and endothermic dissociation of hydrate and ice phases, mixed fluid flow and large changes in fluid pressure. The analysis of available data from past field and laboratory experiments, and the optimization of future field production studies require a formal and robust numerical framework able to capture the very complex behavior of this type of soil. A comprehensive fully coupled THCM formulation has been developed and implemented into a finite element code to tackle problems involving gas hydrates sediments. Special attention is paid to the geomechanical behavior of HBS, and particularly to their response upon hydrate dissociation under loading. The numerical framework has been validated against recent experiments conducted under controlled conditions in the laboratory that challenge the proposed approach and highlight the complex interaction among THCM processes in HBS. The performance of the models in these case studies is highly satisfactory. Finally, the numerical code is applied to analyze the behavior of gas hydrate soils under field-scale conditions exploring different features of material behavior under possible reservoir conditions.

Petrophysical Characterization and Reservoir Simulator for Methane Gas Production from Gulf of Mexico Hydrates

Energy Technology Data Exchange (ETDEWEB)

Kishore Mohanty; Bill Cook; Mustafa Hakimuddin; Ramanan Pitchumani; Damiola Ogunlana; Jon Burger; John Shillinglaw

2006-06-30

Gas hydrates are crystalline, ice-like compounds of gas and water molecules that are formed under certain thermodynamic conditions. Hydrate deposits occur naturally within ocean sediments just below the sea floor at temperatures and pressures existing below about 500 meters water depth. Gas hydrate is also stable in conjunction with the permafrost in the Arctic. Most marine gas hydrate is formed of microbially generated gas. It binds huge amounts of methane into the sediments. Estimates of the amounts of methane sequestered in gas hydrates worldwide are speculative and range from about 100,000 to 270,000,000 trillion cubic feet (modified from Kvenvolden, 1993). Gas hydrate is one of the fossil fuel resources that is yet untapped, but may play a major role in meeting the energy challenge of this century. In this project novel techniques were developed to form and dissociate methane hydrates in porous media, to measure acoustic properties and CT properties during hydrate dissociation in the presence of a porous medium. Hydrate depressurization experiments in cores were simulated with the use of TOUGHFx/HYDRATE simulator. Input/output software was developed to simulate variable pressure boundary condition and improve the ease of use of the simulator. A series of simulations needed to be run to mimic the variable pressure condition at the production well. The experiments can be matched qualitatively by the hydrate simulator. The temperature of the core falls during hydrate dissociation; the temperature drop is higher if the fluid withdrawal rate is higher. The pressure and temperature gradients are small within the core. The sodium iodide concentration affects the dissociation pressure and rate. This procedure and data will be useful in designing future hydrate studies.

In Vivo skin hydration and anti-erythema effects of Aloe vera, Aloe ferox and Aloe marlothii gel materials after single and multiple applications.

Science.gov (United States)

Fox, Lizelle T; du Plessis, Jeanetta; Gerber, Minja; van Zyl, Sterna; Boneschans, Banie; Hamman, Josias H

2014-04-01

To investigate the skin hydrating and anti-erythema activity of gel materials from Aloe marlothii A. Berger and A. ferox Mill. in comparison to that of Aloe barbadensis Miller (Aloe vera) in healthy human volunteers. Aqueous solutions of the polisaccharidic fractions of the selected aloe leaf gel materials were applied to the volar forearm skin of female subjects. The hydration effect of the aloe gel materials were measured with a Corneometer(®) CM 825, Visioscan(®) VC 98 and Cutometer(®) dual MPA 580 after single and multiple applications. The Mexameter(®) MX 18 was used to determine the anti-erythema effects of the aloe material solutions on irritated skin areas. The A. vera and A. marlothii gel materials hydrated the skin after a single application, whereas the A. ferox gel material showed dehydration effects compared to the placebo. After multiple applications all the aloe materials exhibited dehydration effects on the skin. Mexameter(®) readings showed that A. vera and A. ferox have anti-erythema activity similar to that of the positive control group (i.e. hydrocortisone gel) after 6 days of treatment. The polysaccharide component of the gel materials from selected aloe species has a dehydrating effect on the skin after multiple applications. Both A. vera and A. ferox gel materials showed potential to reduce erythema on the skin similar to that of hydrocortisone gel.

[Laser Raman Spectroscopy and Its Application in Gas Hydrate Studies].

Science.gov (United States)

Fu, Juan; Wu, Neng-you; Lu, Hai-long; Wu, Dai-dai; Su, Qiu-cheng

2015-11-01

Gas hydrates are important potential energy resources. Microstructural characterization of gas hydrate can provide information to study the mechanism of gas hydrate formation and to support the exploitation and application of gas hydrate technology. This article systemly introduces the basic principle of laser Raman spectroscopy and summarizes its application in gas hydrate studies. Based on Raman results, not only can the information about gas composition and structural type be deduced, but also the occupancies of large and small cages and even hydration number can be calculated from the relative intensities of Raman peaks. By using the in-situ analytical technology, laser Raman specstropy can be applied to characterize the formation and decomposition processes of gas hydrate at microscale, for example the enclathration and leaving of gas molecules into/from its cages, to monitor the changes in gas concentration and gas solubility during hydrate formation and decomposition, and to identify phase changes in the study system. Laser Raman in-situ analytical technology has also been used in determination of hydrate structure and understanding its changing process under the conditions of ultra high pressure. Deep-sea in-situ Raman spectrometer can be employed for the in-situ analysis of the structures of natural gas hydrate and their formation environment. Raman imaging technology can be applied to specify the characteristics of crystallization and gas distribution over hydrate surface. With the development of laser Raman technology and its combination with other instruments, it will become more powerful and play a more significant role in the microscopic study of gas hydrate.

Multicomponent modelling of Portland cement hydration reactions

NARCIS (Netherlands)

Ukrainczyk, N.; Koenders, E.A.B.; Van Breugel, K.

2012-01-01

The prospect of cement and concrete technologies depends on more in depth understanding of cement hydration reactions. Hydration reaction models simulate the development of the microstructures that can finally be used to estimate the cement based material properties that influence performance and

Chemical alteration of cement hydrates by dissolution

International Nuclear Information System (INIS)

Sugiyama, Daisuke; Fujita, Tomonari; Nakanishi, Kiyoshi

2000-01-01

Cementitious material is a potential waste packaging and backfilling material for the radioactive waste disposal, and is expected to provide both physical and chemical containment. In particular, the sorption of radionuclides onto cementitious material and the ability to provide a high pH condition are very important parameters when considering the release of radionuclides from radioactive wastes. For the long term, in the geological disposal environment, cement hydrates will be altered by, for example, dissolution, chemical reaction with ions in the groundwater, and hydrothermal reaction. Once the composition or crystallinity of the constituent minerals of a cement hydrate is changed by these processes, the pH of the repository buffered by cementitious material and its sorption ability might be affected. However, the mechanism of cement alteration is not yet fully understood. In this study, leaching experiments of some candidate cements for radioactive waste disposal were carried out. Hydrated Ordinary Portland Cement (OPC), Blast Furnace Slag blended cement (OPC/BFS) and Highly containing Flyash and Silicafume Cement (HFSC) samples were contacted with distilled water at liquid:solid ratios of 10:1, 100:1 and 1000:1 at room temperature for 200 days. In the case of OPC, Ca(OH) 2 dissolved at high liquid:solid ratios. The specific surface area of all cement samples increased by leaching process. This might be caused by further hydration and change of composition of constituent minerals. A model is presented which predicts the leaching of cement hydrates and the mineral composition in the hydrated cement solid phase, including the incongruent dissolution of CSH gel phases and congruent dissolution of Ca(OH) 2 , Ettringite and Hydrotalcite. Experimental results of dissolution of Ca-O-H and Ca-Si-O-H phases were well predicted by this model. (author)

In situ Low-temperature Pair Distribution Function (PDF) Analysis of CH4 and CO2 Hydrates

Science.gov (United States)

Cladek, B.; Everett, M.; McDonnell, M.; Tucker, M.; Keffer, D.; Rawn, C.

2017-12-01

Gas hydrates occur in ocean floor and sub-surface permafrost deposits and are stable at moderate to high pressures and low temperatures. They are a clathrate structure composed of hydrogen bonded water cages that accommodate a wide variety of guest molecules. CO2 and CH4 hydrates both crystallize as the cubic sI hydrate and can form a solid solution. Natural gas hydrates are interesting as a potential methane source and for CO2 sequestration. Long-range diffraction studies on gas hydrates give valuable structural information but do not provide a detailed understanding of the disordered gas molecule interactions with the host lattice. In-situ low temperature total scattering experiments combined with pair distribution function (PDF) analysis are used to investigate the gas molecule motions and guest-cage interactions. CO2 and methane hydrates exhibit different decomposition behavior, and CO2 hydrate has a smaller lattice parameter despite it being a relatively larger molecule. Total scattering studies characterizing both the short- and long-range order simultaneously help to elucidate the structural source of these phenomena. Low temperature neutron total scattering data were collected using the Nanoscale Ordered MAterials Diffractometer (NOMAD) beamline at the Spallation Neutron Source (SNS) on CO2 and CH4 hydrates synthesized with D2O. Guest molecule motion within cages and interactions between gases and cages are investigated through the hydrate stability and decomposition regions. Data were collected from 2-80 K at a pressure of 55 mbar on CO2 and CH4 hydrates, and from 80-270 K at 25 bar on CH4 hydrate. The hydrate systems were modeled with classical molecular dynamic (MD) simulations to provide an analysis of the total energy into guest-guest, guest-host and host-host contributions. Combined Reitveld and Reverse Monte Carlo (RMC) structure refinement were used to fit models of the data. This combined modeling and simulation characterizes the effects of CO2 and

Structural transformations of sVI tert-butylamine hydrates to sII binary hydrates with methane.

Science.gov (United States)

Prasad, Pinnelli S R; Sugahara, Takeshi; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

2009-10-22

Binary clathrate hydrates with methane (CH(4), 4.36 A) and tert-butylamine (t-BuNH(2), 6.72 A) as guest molecules were synthesized at different molar concentrations of t-BuNH(2) (1.00-9.31 mol %) with methane at 7.0 MPa and 250 K, and were characterized by powder X-ray diffraction (PXRD) and Raman microscopy. A structural transformation from sVI to sII of t-BuNH(2) hydrate was clearly observed on pressurizing with methane. The PXRD showed sII signatures and the remnant sVI signatures were insignificant, implying the metastable nature of sVI binary hydrates. Raman spectroscopic data on these binary hydrates suggest that the methane molecules occupy the small cages and vacant large cages. The methane storage capacity in this system was nearly doubled to approximately 6.86 wt % for 5.56 mol % > t-BuNH(2) > 1.0 mol %.

Practical materials characterization

CERN Document Server

2014-01-01

Presents cross-comparison between materials characterization techniquesIncludes clear specifications of strengths and limitations of each technique for specific materials characterization problemFocuses on applications and clear data interpretation without extensive mathematics

In Vivo skin hydration and anti-erythema effects of Aloe vera, Aloe ferox and Aloe marlothii gel materials after single and multiple applications

Science.gov (United States)

Fox, Lizelle T.; du Plessis, Jeanetta; Gerber, Minja; van Zyl, Sterna; Boneschans, Banie; Hamman, Josias H.

2014-01-01

Objective: To investigate the skin hydrating and anti-erythema activity of gel materials from Aloe marlothii A. Berger and A. ferox Mill. in comparison to that of Aloe barbadensis Miller (Aloe vera) in healthy human volunteers. Materials and Methods: Aqueous solutions of the polisaccharidic fractions of the selected aloe leaf gel materials were applied to the volar forearm skin of female subjects. The hydration effect of the aloe gel materials were measured with a Corneometer® CM 825, Visioscan® VC 98 and Cutometer® dual MPA 580 after single and multiple applications. The Mexameter® MX 18 was used to determine the anti-erythema effects of the aloe material solutions on irritated skin areas. Results: The A. vera and A. marlothii gel materials hydrated the skin after a single application, whereas the A. ferox gel material showed dehydration effects compared to the placebo. After multiple applications all the aloe materials exhibited dehydration effects on the skin. Mexameter® readings showed that A. vera and A. ferox have anti-erythema activity similar to that of the positive control group (i.e. hydrocortisone gel) after 6 days of treatment. Conclusion: The polysaccharide component of the gel materials from selected aloe species has a dehydrating effect on the skin after multiple applications. Both A. vera and A. ferox gel materials showed potential to reduce erythema on the skin similar to that of hydrocortisone gel. PMID:24991119

Molecular analysis of petroleum derived compounds that adsorb onto gas hydrate surfaces

International Nuclear Information System (INIS)

Borgund, Anna E.; Hoiland, Sylvi; Barth, Tanja; Fotland, Per; Askvik, Kjell M.

2009-01-01

Field observations have shown that some streams of water, gas and crude oil do not form gas hydrate plugs during petroleum production even when operating within thermodynamic conditions for hydrate formation. Also, when studied under controlled laboratory conditions, some oils are found to form hydrate dispersed systems whereas others form plugs. Oils with low tendency to form hydrate plugs are believed to contain natural hydrate plug inhibiting components (NICs) that adsorb onto the hydrate surface, making them less water-wet and preventing the particles from agglomerating into large hydrate clusters. The molecular structure of the NICs is currently unknown. In this work, hydrate adsorbing components were extracted from crude oils using freon hydrates as an extraction phase. The fractions were found to be enriched in polar material, and more polar material is associated with hydrates generated in biodegraded crude oils than in non-biodegraded oils. Various fractionation schemes and analytical techniques have been applied in the search for molecular characterisation. The average molecular weights were found to be approximately 500 g/mole. GC-MS chromatograms show a large UCM (Unresolved Complex Mixture). Thus, GC-MS has a limited potential for identification of compounds. A commercial biosurfactant was used as a model compound in the search for similar structures in the extracts. The results from analysis of the hydrate adsorbing components suggest that the type and structure are more important for hydrate morphology than the amount of material adsorbed.

Geological modeling for methane hydrate reservoir characterization in the eastern Nankai Trough, offshore Japan

Science.gov (United States)

Tamaki, M.; Komatsu, Y.; Suzuki, K.; Takayama, T.; Fujii, T.

2012-12-01

The eastern Nankai trough, which is located offshore of central Japan, is considered as an attractive potential resource field of methane hydrates. Japan Oil, Gas and Metals National Corporation is planning to conduct a production test in early 2013 at the AT1 site in the north slope of Daini-Atsumi Knoll in the eastern Nankai Trough. The depositional environment of methane hydrate-bearing sediments around the production test site is a deep submarine-fan turbidite system, and it is considered that the reservoir properties should show lateral as well as vertical heterogeneity. Since the variations in the reservoir heterogeneity have an impact on the methane hydrate dissociation and gas production performance, precise geological models describing reservoir heterogeneity would be required for the evaluation of reservoir potentials. In preparation for the production test, 3 wells; two monitoring boreholes (AT1-MC and AT1-MT1) and a coring well (AT1-C), were newly acquired in 2012. In addition to a geotechnical hole drilling survey in 2011 (AT1-GT), totally log data from 2 wells and core data from 2 wells were obtained around the production test site. In this study, we conducted well correlations between AT1 and A1 wells drilled in 2003 and then, 3D geological models were updated including AT1 well data in order to refine hydrate reservoir characterization around the production test site. The results of the well correlations show that turbidite sand layers are characterized by good lateral continuity, and give significant information for the distribution morphology of sand-rich channel fills. We also reviewed previously conducted 3D geological models which consist of facies distributions and petrophysical properties distributions constructed from integration of 3D seismic data and a well data (A1 site) adopting a geostatistical approach. In order to test the practical validity of the previously generated models, cross-validation was conducted using AT1 well data. The

Clathrate Hydrates for Thermal Energy Storage in Buildings: Overview of Proper Hydrate-Forming Compounds

Directory of Open Access Journals (Sweden)

Beatrice Castellani

2014-09-01

Full Text Available Increasing energy costs are at the origin of the great progress in the field of phase change materials (PCMs. The present work aims at studying the application of clathrate hydrates as PCMs in buildings. Clathrate hydrates are crystalline structures in which guest molecules are enclosed in the crystal lattice of water molecules. Clathrate hydrates can form also at ambient pressure and present a high latent heat, and for this reason, they are good candidates for being used as PCMs. The parameter that makes a PCM suitable to be used in buildings is, first of all, a melting temperature at about 25 °C. The paper provides an overview of groups of clathrate hydrates, whose physical and chemical characteristics could meet the requirements needed for their application in buildings. Simulations with a dynamic building simulation tool are carried out to evaluate the performance of clathrate hydrates in enhancing thermal comfort through the moderation of summer temperature swings and, therefore, in reducing energy consumption. Simulations suggest that clathrate hydrates have a potential in terms of improvement of indoor thermal comfort and a reduction of energy consumption for cooling. Cooling effects of 0.5 °C and reduced overheating hours of up to 1.1% are predicted.

Effect of mass concentration of composite phase change material CA-DE on HCFC-141b hydrate induction time and system stability

Science.gov (United States)

Li, Juan; Sun, Zhigao; Liu, Chenggang; Zhu, Minggui

2018-03-01

HCFC-141b hydrate is a new type of environment-friendly cold storage medium which may be adopted to balance energy supply and demand, achieve peak load shifting and energy saving, wherein the hydrate induction time and system stability are key factors to promote and realize its application in industrial practice. Based on step cooling curve measurement, two kinds of aliphatic hydrocarbon organics, n-capric acid (CA) and lauryl alcohol (DE), were selected to form composite phase change material and to promote the generation of HCFC-141b hydrate. Five kinds of CA-DE mass concentration were chosen to compare the induction time and hydration system stability. In order to accelerate temperature reduction rate, the metal Cu with high heat conductivity performance was adopted to conduct out the heat generated during phase change. Instability index was introduced to appraise system stability. Experimental results show that phase change temperature and sub-cooling degree of CA-DE is 11.1°C and 3.0°C respectively, which means it is a preferable medium for HCFC-141b hydrate formation. For the experimental hydration systems, segmented emulsification is achieved by special titration manner to avoid rapid layering under static condition. Induction time can achieve up to 23.3min with the densest HCFC-141b hydrate and the lowest instability index, wherein CA-DE mass concentration is 3%.

Effects of Nanosilica on Early Age Stages of Cement Hydration

Directory of Open Access Journals (Sweden)

Forood Torabian Isfahani

2017-01-01

Full Text Available Effects of nanosilica on cement hydration have been broadly investigated in the literature and early age cement hydration, as a whole, has been mainly considered, disregarding the substages of the hydration. The hydration of cement is characterized by different substages and nanosilica effect on the hydration could be a result of diverse, even contradictory, behavior of nanosilica in individual stages of the hydration. In this study, effects of nanosilica on different substages of cement hydration are investigated. Isothermal calorimetry results show that at early ages (initial 72 hours the effects of nanosilica depend on the phenomenon by which the hydration is governed: when the hydration is chemically controlled, that is, during initial reaction, dormant period, and acceleratory period, the hydration rate is accelerated by adding nanosilica; when the hydration is governed by diffusion process, that is, during postacceleratory period, the hydration rate is decelerated by adding nanosilica. The Thermal Gravimetric Analysis on the samples at the hardened state (after 28 days of curing reveals that, after adding nanosilica, the hydration degree slightly increased compared to the plain paste.

Thermal conductivity of hydrate-bearing sediments

Science.gov (United States)

Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn D.

2009-01-01

A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate–saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate–bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

Influence of agglomeration of a recycled cement additive on the hydration and microstructure development of cement based materials

NARCIS (Netherlands)

Yu, R.; Shui, Z.H.

2013-01-01

This paper presents a study, including experimental and mechanism analysis, on investigating the effect of agglomeration of a recycled cement additive on the hydration and microstructure development of cement based materials. The recycled additive is firstly produced form waste hardened cement paste

The influence of raw material, added emulsifying salt and spray drying on cheese powder structure and hydration properties

DEFF Research Database (Denmark)

Felix da Silva, Denise; Larsen, Flemming Hofmann; Hougaard, Anni Bygvrå

2017-01-01

The present work has evaluated how raw material, addition of emulsifying salts (ES) and drying technology affect particle characteristics, structure, and hydration of cheese powders. In this context the spray drying technology induced the strongest effect on morphology and swelling of cheese powder...

Experimental solid state NMR of gas hydrates : problems and solutions

Energy Technology Data Exchange (ETDEWEB)

Moudrakovski, I.; Lu, H.; Ripmeester, J. [National Research Council of Canada, Ottawa, ON (Canada). Steacie Inst. for Molecular Sciences; Kumar, R.; Susilo, R. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Luzi, M. [GeoForschungsZentrum Potsdam, Potsdam (Germany)

2008-07-01

Solid State NMR is a suitable spectroscopic technique for hydrate research for several reasons, including its capability to distinguish between different structural types of hydrates, its quantitative nature and potential for both in-situ and time resolved experiments. This study illustrated the applications of solid state NMR for compositional and structural studies of clathrate hydrates, with particular emphasis on experimental techniques and potential ways to overcome technical difficulties. In order to use the method to its full capacity, some instrumental developments are needed to adapt it to the specific experimental requirements of hydrate studies, such as very low temperatures and high pressures. This presentation discussed the quantification of the Carbon-13 spectra with examples from natural and synthetic hydrates prepared from multi-component mixtures of hydrocarbons. The main approach used for the first two examples was Carbon-13 NMR with Magic Angle Spinning (MAS) at -100 degrees C. The detailed characterization of mixed hydrogen hydrates required low temperature hydrogen MAS. The quantification problems encountered during these experiments were also discussed. The purpose of these recent experimental developments was to prompt wider application of Solid State NMR in hydrate research. NMR proved to be a viable method for analyzing the composition and structure of multi-component mixed gas hydrates; characterizing natural gas hydrates; and, evaluating the formation conditions and properties of mixed hydrogen hydrates. The limitations of the method were highlighted and sensible choices of experimental conditions and techniques that ensure accurate results were discussed. 34 refs., 10 figs.

Hydrate-bearing Submarine Landslides in the Orca Basin, Gulf of Mexico

Science.gov (United States)

Sawyer, D.; Mason, A.; Cook, A.; Portnov, A.; Hillman, J.

2017-12-01

The co-occurrence of submarine landslides and hydrate-bearing sediment suggests that hydrates may play a role in landslide triggering and/or the mobility and dynamic characteristics of the submarine landslide. In turn, the removal of large sections of seafloor perturbs the hydrate stability field by removing overburden pressure and disturbing the temperature field. These potential hydrate-landslide feedbacks are not well understood. Here we combine three-dimensional seismic and petrophysical logs to characterize the deposits of submarine landslides that failed from hydrate-bearing sediments in the Orca Basin in the northern Gulf of Mexico. The Orca Basin contains a regionally mappable bottom simulating reflector, hydrate saturations within sands and muds, as well as numerous landslides. In addition, the Orca Basin features a well-known 123 km2 anoxic hypersaline brine pool that is actively being fed by outcropping salt. Lying at the bottom of the brine pool are deposits of submarine landslides. Slope instability in the Orca Basin is likely associated with near-seafloor salt tectonics. The most prominent landslide scar observable on the seafloor has a correlative deposit that now lies at the bottom of the brine pool 11.6 km away. The headwall is amphitheater-shaped with an average height of 80 meters and with only a minor amount of rubble remaining near the headwall. A total of 8.7 km3 of material was removed and deposited between the lower slopes of the basin and the base of the brine pool. Around the perimeter of the landslide headwall, two industry wells were drilled and well logs show elevated resistivity that are likely caused by gas hydrate. The slide deposits have a chaotic seismic facies with large entrained blocks and the headwall area does not retain much original material, which together suggests a relatively mobile style of landslide and therefore may have generated a wave upon impacting the brine pool. Such a slide-induced wave may have sloshed

Electric double-layer capacitor based on an ionic clathrate hydrate.

Science.gov (United States)

Lee, Wonhee; Kwon, Minchul; Park, Seongmin; Lim, Dongwook; Cha, Jong-Ho; Lee, Huen

2013-07-01

Herein, we suggest a new approach to an electric double-layer capacitor (EDLC) that is based on a proton-conducting ionic clathrate hydrate (ICH). The ice-like structures of clathrate hydrates, which are comprised of host water molecules and guest ions, make them suitable for applications in EDLC electrolytes, owing to their high proton conductivities and thermal stabilities. The carbon materials in the ICH Me4NOH⋅5 H2O show a high specific capacitance, reversible charge-discharge behavior, and a long cycle life. The ionic-hydrate complex provides the following advantages in comparison with conventional aqueous and polymer electrolytes: 1) The ICH does not cause leakage problems under normal EDLC operating conditions. 2) The hydrate material can be utilized itself, without requiring any pre-treatments or activation for proton conduction, thus shortening the preparation procedure of the EDLC. 3) The crystallization of the ICH makes it possible to tailor practical EDLC dimensions because of its fluidity as a liquid hydrate. 4) The hydrate solid electrolyte exhibits more-favorable electrochemical stability than aqueous and polymer electrolytes. Therefore, ICH materials are expected to find practical applications in versatile energy devices that incorporate electrochemical systems. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ab initio modelling of methane hydrate thermophysical properties.

Science.gov (United States)

Jendi, Z M; Servio, P; Rey, A D

2016-04-21

The key thermophysical properties of methane hydrate were determined using ab initio modelling. Using density functional theory, the second-order elastic constants, heat capacity, compressibility, and thermal expansion coefficient were calculated. A wide and relevant range of pressure-temperature conditions were considered, and the structures were assessed for stability using the mean square displacement and radial distribution functions. Methane hydrate was found to be elastically isotropic with a linear dependence of the bulk modulus on pressure. Equally significant, multi-body interactions were found to be important in hydrates, and water-water interactions appear to strongly influence compressibility like in ice Ih. While the heat capacity of hydrate was found to be higher than that of ice, the thermal expansion coefficient was significantly lower, most likely due to the lower rigidity of hydrates. The mean square displacement gave important insight into stability, heat capacity, and elastic moduli, and the radial distribution functions further confirmed stability. The presented results provide a much needed atomistic thermoelastic characterization of methane hydrates and are essential input for the large-scale applications of hydrate detection and production.

Improvement of performance of ultra-high performance concrete based composite material added with nano materials

Directory of Open Access Journals (Sweden)

Pang Jinchang

2016-03-01

Full Text Available Ultra-high performance concrete (UHPC, a kind of composite material characterized by ultra high strength, high toughness and high durability. It has a wide application prospect in engineering practice. But there are some defects in concrete. How to improve strength and toughness of UHPC remains to be the target of researchers. To obtain UHPC with better performance, this study introduced nano-SiO2 and nano-CaCO3 into UHPC. Moreover, hydration heat analysis, X-Ray Diffraction (XRD, mercury intrusion porosimetry (MIP and nanoindentation tests were used to explore hydration process and microstructure. Double-doped nanomaterials can further enhance various mechanical performances of materials. Nano-SiO2 can promote early progress of cement hydration due to its high reaction activity and C-S-H gel generates when it reacts with cement hydration product Ca(OH2. Nano-CaCO3 mainly plays the role of crystal nucleus effect and filling effect. Under the combined action of the two, the composite structure is denser, which provides a way to improve the performance of UHPC in practical engineering.

Impact of Compound Hydrate Dynamics on Phase Boundary Changes

Science.gov (United States)

Osegovic, J. P.; Max, M. D.

2006-12-01

Compound hydrate reactions are affected by the local concentration of hydrate forming materials (HFM). The relationship between HFM composition and the phase boundary is as significant as temperature and pressure. Selective uptake and sequestration of preferred hydrate formers (PF) has wide ranging implications for the state and potential use of natural hydrate formation, including impact on climate. Rising mineralizing fluids of hydrate formers (such as those that occur on Earth and are postulated to exist elsewhere in the solar system) will sequester PF before methane, resulting in a positive relationship between depth and BTU content as ethane and propane are removed before methane. In industrial settings the role of preferred formers can separate gases. When depressurizing gas hydrate to release the stored gas, the hydrate initial composition will set the decomposition phase boundary because the supporting solution takes on the composition of the hydrate phase. In other settings where hydrate is formed, transported, and then dissociated, similar effects can control the process. The behavior of compound hydrate systems can primarily fit into three categories: 1) In classically closed systems, all the material that can form hydrate is isolated, such as in a sealed laboratory vessel. In such systems, formation and decomposition are reversible processes with observed hysteresis related to mass or heat transfer limitations, or the order and magnitude in which individual hydrate forming gases are taken up from the mixture and subsequently released. 2) Kinetically closed systems are exposed to a solution mass flow across a hydrate mass. These systems can have multiple P-T phase boundaries based on the local conditions at each face of the hydrate mass. A portion of hydrate that is exposed to fresh mineralizing solution will contain more preferred hydrate formers than another portion that is exposed to a partially depleted solution. Examples of kinetically closed

Surface modification and characterization of magnesium hydroxide sulfate hydrate nanowhiskers

Energy Technology Data Exchange (ETDEWEB)

Gao Chuanhui [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); Li Xianguo, E-mail: chuanhuigao@foxmail.com [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China); Feng Lijuan; Lu Shaoyan; Liu Jinyan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao 266100 (China)

2010-03-01

In order to enhance the compatibility with plastic polymers, magnesium hydroxide sulfate hydrate (MHSH) nanowhiskers were modified through grafting methyl methacrylate (MMA) on the surface of the nanowhiskers by emulsion polymerization. The influences of the reaction time, MMA monomer content, adding speed of monomer and the reaction temperature on the grafting ratio were investigated. Thermogravimetry (TG), Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray (EDX) spectroscopy and surface contact angle measurement were used to characterize the effect of surface modification. The results showed that the MHSH nanowhiskers were uniformly coated by polymethyl methacrylate (PMMA), and a well-defined core-shell hybrid structure of MHSH/PMMA was obtained. The surface contact angle of the hybrid whiskers increased to 87.32 deg. from 12.71 deg. and the whiskers surface was changed from hydrophilic to lipophilic.

Investigating the Metastability of Clathrate Hydrates for Energy Storage

Energy Technology Data Exchange (ETDEWEB)

Koh, Carolyn Ann [Colorado School of Mines, Golden, CO (United States)

2014-11-18

Important breakthrough discoveries have been achieved from the DOE award on the key processes controlling the synthesis and structure-property relations of clathrate hydrates, which are critical to the development of clathrate hydrates as energy storage materials. Key achievements include: (i) the discovery of key clathrate hydrate building blocks (stable and metastable) leading to clathrate hydrate nucleation and growth; (ii) development of a rapid clathrate hydrate synthesis route via a seeding mechanism; (iii) synthesis-structure relations of H2 + CH4/CO2 binary hydrates to control thermodynamic requirements for energy storage and sequestration applications; (iv) discovery of a new metastable phase present during clathrate hydrate structural transitions. The success of our research to-date is demonstrated by the significant papers we have published in high impact journals, including Science, Angewandte Chemie, J. Am. Chem. Soc. Intellectual Merits of Project Accomplishments: The intellectual merits of the project accomplishments are significant and transformative, in which the fundamental coupled computational and experimental program has provided new and critical understanding on the key processes controlling the nucleation, growth, and thermodynamics of clathrate hydrates containing hydrogen, methane, carbon dioxide, and other guest molecules for energy storage. Key examples of the intellectual merits of the accomplishments include: the first discovery of the nucleation pathways and dominant stable and metastable structures leading to clathrate hydrate formation; the discovery and experimental confirmation of new metastable clathrate hydrate structures; the development of new synthesis methods for controlling clathrate hydrate formation and enclathration of molecular hydrogen. Broader Impacts of Project Accomplishments: The molecular investigations performed in this project on the synthesis (nucleation & growth)-structure-stability relations of clathrate

Salt hydrates and other phase-change materials

Energy Technology Data Exchange (ETDEWEB)

Cantor, S.

1978-01-01

The objectives of the project are: to ascertain thermal performance of Na/sub 2/SO/sub 4/ . 10H/sub 2/O and other incongruently melting salt hydrates by calorimetric investigation of melting and freezing; and select compounds and mixtures suitable for isothermal heat storage within the range, 90 to 250/sup 0/C. Selection is to be used on laboratory evaluation as well as on economic and technical screening criteria.

Reconsideration on Hydration of Sodium Ion: From Micro-Hydration to Bulk Hydration

Science.gov (United States)

Yongquan, Zhou; Chunhui, Fang; Yan, Fang; Fayan, Zhu; Haiwen, Ge; Hongyan, Liu

2017-12-01

Micro hydration structures of the sodium ion, [Na(H2O) n ]+, n = 1-12, were probed by density functional theory (DFT) at B3LYP/aug-cc-pVDZ level in both gaseous and aqueous phase. The predicted equilibrium sodium-oxygen distance of 0.240 nm at the present level of theory. The four-, five- and six-coordinated cluster can transform from each other at the ambient condition. The analysis of the successive water binding energy and natural charge population (NBO) on Na+ clearly shows that the influence of Na+ on the surrounding water molecules goes beyond the first hydration shell with the hydration number of 6. The Car-Parrinello molecular dynamic simulation shows that only the first hydration sphere can be found, and the hydration number of Na+ is 5.2 and the hydration distance ( r Na-O) is 0.235 nm. All our simulations mentioned in the present paper show an excellent agreement with the diffraction result from X-ray scattering study.

Hydrate-Bearing Clayey Sediments: Morphology, Physical Properties, Production and Engineering/Geological Implications

Energy Technology Data Exchange (ETDEWEB)

Dai, Sheng [Georgia Tech Research Corporation, Atlanta, GA (United States); Santamarina, J. Carlos [King Abdulaziz Univ., Jeddah (Saudi Arabia)

2017-12-30

Fine-grained sediments host more than 90 percent of global gas hydrate accumulation. However, hydrate formation in clay-dominated sediments is less understood and characterized than other types of hydrate occurrence. There is an inadequate understanding of hydrate formation mechanisms, segregation structures, hydrate lens topology, system connectivity, and physical macro-scale properties of clay-dominated hydrate-bearing sediments. This situation hinders further analyses of the global carbon budget as well as engineering challenges/solutions related to hydrate instability and production. This project studies hydrate-bearing clay-dominated sediments with emphasis on the enhanced fundamental understanding of hydrate formation and resulting morphology, the development laboratory techniques to emulate natural hydrate formations, the assessment of analytical tools to predict physical properties, the evaluation of engineering and geological implications, and the advanced understanding of gas production potential from finegrained sediments.

Hydration Control of the Mechanical and Dynamical Properties of Cellulose

Energy Technology Data Exchange (ETDEWEB)

Petridis, Loukas; O’Neill, Hugh M.; Johnsen, Mariah [Ripon College, Ripon, Wisconsin 54971, United States; Fan, Bingxin [Department; Schulz, Roland [Department; Mamontov, Eugene; Maranas, Janna [Department; Langan, Paul [Department; Smith, Jeremy C. [Department

2014-10-13

The mechanical and dynamical properties of cellulose, the most abundant biomolecule on earth, are essential for its function in plant cell walls and advanced biomaterials. Cellulose is almost always found in a hydrated state, and it is therefore important to understand how hydration influences its dynamics and mechanics. Here, the nanosecond-time scale dynamics of cellulose is characterized using dynamic neutron scattering experiments and molecular dynamics (MD) simulation. The experiments reveal that hydrated samples exhibit a higher average mean-square displacement above ~240 K. The MD simulation reveals that the fluctuations of the surface hydroxymethyl atoms determine the experimental temperature and hydration dependence. The increase in the conformational disorder of the surface hydroxymethyl groups with temperature follows the cellulose persistence length, suggesting a coupling between structural and mechanical properties of the biopolymer. In the MD simulation, 20% hydrated cellulose is more rigid than the dry form, due to more closely packed cellulose chains and water molecules bridging cellulose monomers with hydrogen bonds. This finding may have implications for understanding the origin of strength and rigidity of secondary plant cell walls. The detailed characterization obtained here describes how hydration-dependent increased fluctuations and hydroxymethyl disorder at the cellulose surface lead to enhancement of the rigidity of this important biomolecule.

The structure of hydrate bearing fine grained marine sediments

Energy Technology Data Exchange (ETDEWEB)

Priest, J.; Kingston, E.; Clayton, C. [Southampton Univ., Highfield (United Kingdom). School of Civil Engineering and the Environment; Schultheiss, P.; Druce, M. [Geotek Ltd., Daventry (United Kingdom)

2008-07-01

This paper discussed the structure of naturally occurring methane gas hydrates in fine-grained sediments from core samples recovered using in situ pressures from the eastern margin of the Indian Ocean. High resolution X-ray computed tomography (CT) images were taken of gas hydrate cores. The hydrate structure was examined and comparisons were made between low resolution X-ray images obtained on the cores prior to sub-sectioning and depressurization procedures. The X-ray images showed the presence of high-angle, sub-parallel veins within the recovered sediments. The scans indicated that the hydrates occurred as fracture filing veins throughout the core. Fracture orientation was predominantly sub-vertical. Thick millimetric hydrate veins were composed of sub-millimetric veins with variations in fracture angle. The analysis indicated that hydrate formation was episodic in nature and subject to changes in the stress regime. Results of the study showed that depressurization and subsequent freezing alter the structure of the sediment even when the gas hydrate has not been altered. A large proportion of the hydrate survived when outside of its stability region. The self-preserving behaviour of the hydrate was attributed to the endothermic nature of gas hydrate dissociation. It was concluded that the accurate physical characterization of gas hydrates can only be conducted when the core section remains under in situ stress conditions. 13 refs., 9 figs.

Supramolecular Organization of Nonstoichiometric Drug Hydrates: Dapsone

Science.gov (United States)

Braun, Doris E.; Griesser, Ulrich J.

2018-01-01

The observed moisture- and temperature dependent transformations of the dapsone (4,4′-diaminodiphenyl sulfone, DDS) 0. 33-hydrate were correlated to its structure and the number and strength of the water-DDS intermolecular interactions. A combination of characterization techniques was used, including thermal analysis (hot-stage microscopy, differential scanning calorimetry and thermogravimetric analysis), gravimetric moisture sorption/desorption studies and variable humidity powder X-ray diffraction, along with computational modeling (crystal structure prediction and pair-wise intermolecular energy calculations). Depending on the relative humidity the hydrate contains between 0 and 0.33 molecules of water per molecule DDS. The crystal structure is retained upon dehydration indicating that DDS hydrate shows a non-stoichiometric (de)hydration behavior. Unexpectedly, the water molecules are not located in structural channels but at isolated-sites of the host framework, which is counterintuitively for a hydrate with non-stoichiometric behavior. The water-DDS interactions were estimated to be weaker than water-host interactions that are commonly observed in stoichiometric hydrates and the lattice energies of the isomorphic dehydration product (hydrate structure without water molecules) and (form III) differ only by ~1 kJ mol−1. The computational generation of hypothetical monohydrates confirms that the hydrate with the unusual DDS:water ratio of 3:1 is more stable than a feasible monohydrate structure. Overall, this study highlights that a deeper understanding of the formation of hydrates with non-stoichiometric behavior requires a multidisciplinary approach including suitable experimental and computational methods providing a firm basis for the development and manufacturing of high quality drug products. PMID:29520359

Preparation and characterization of hybrid materials from natural chrysotile; Preparacao e caracterizacao de materiais hibridos a partir da crisotila natural

Energy Technology Data Exchange (ETDEWEB)

Giraldelli, M.G.; Silva, M.L.C.P., E-mail: marciogiraldelli@hotmail.co [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia

2010-07-01

Special attention has been given to the development of new materials from natural chrysotile. This fiber has about 40% silicon oxide in its structure with an outer layer of brucite (MgOH{sub 2}). With the aim of obtaining a material with a more uniform structure, acid leaching was performed to remove the outer layer of brucite, resulting in a silicon oxide hydrate. This material was used as support for the deposition of Nb{sub 2}O{sub 5}.nH{sub 2}O. The Nb{sub 2}O{sub 5}.nH{sub 2}O was prepared by conventional precipitation using as starting material niobium metallic. In this study, we performed the synthesis and characterization of the material SiO{sub 2}.nH{sub 2}O / Nb{sub 2}O{sub 5}.nH{sub 2}O 1:1. Both chrysotile as niobium are widely available national resources, which confirms the economic viability of resource use. The materials studied were characterized by XRD, SEM and TG/DTG. (author)

Characterization of Limestone as Raw Material to Hydrated Lime

Science.gov (United States)

Salem Hwidi, Rajeb; Nuraiti Tengku Izhar, Tengku; Saad, Farah Naemah Mohd

2018-03-01

In Malaysia, limestone is essentially important for the economic growth as raw materials in the industry sector. Nevertheless, a little attention was paid to the physical, chemical, mineralogical, and morphological properties of the limestone using X-ray fluorescence (X-RF), X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM-EDS) respectively. Raw materials (limestone rocks) were collected from Bukit Keteri area, Chuping, Kangar, Perlis, Malaysia. Lab crusher and lab sieved were utilized to prepare five different size of ground limestone at (75 µm, 150 µm, 225 µm, 300, and 425 µm) respectively. It is found that the main chemical composition of bulk limestone was Calcium oxide (CaO) at 97.58 wt.% and trace amount of MnO, Al2O3, and Fe2O3 at 0.02%, 0.35%, and 0.396% respectively. XRD diffractograms showed characteristic peaks of calcite and quartz. Furthermore, main FTIR absorption bands at 1,419, 874.08 and 712.20 cm-1 indicated the presence of calcite. The micrographs showed clearly the difference of samples particle size. Furthermore, EDS peaks of Ca, O, and C elements confirmed the presence of CaCO3 in the samples.

Materials characterization techniques

National Research Council Canada - National Science Library

Zhang, Sam; Li, L; Kumar, Ashok

2009-01-01

"With an emphasis on practical applications and real-world case studies, Materials Characterization Techniques presents the principles of widely used advanced surface and structural characterization...

Evaluation of Nutritional Status and Hydration in Patients on Chronic ...

African Journals Online (AJOL)

Background: Nutrition and hydration of the dialysis patients have major influences on the outcomes of chronic hemodialysis. Purpose: To characterize the states of nutrition and hydration in patients on chronic hemodialysis at Jos University Teaching Hospital (JUTH) and to evaluate the usefulness of measurements by ...

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials.

Science.gov (United States)

Du, Ming; Jacobsen, Chris

2018-01-01

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zero loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 µm (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Finally, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrate-CASM for modeling Methane Hydrate-Bearing Sediments

Science.gov (United States)

De La Fuente Ruiz, M.; Vaunat, J.; Marin Moreno, H.

2017-12-01

A clear understanding of the geomechanical behavior of methane hydrate-bearing sediments (MHBS) is crucial to assess the stability of the seafloor and submarine infrastructures to human and natural loading changes. Here we present the Hydrate-CASM, a new elastoplastic constitutive model to predict the geomechanical behavior of MHBS. Our model employs the critical state model CASM (Clay and Sand Model) because of its flexibility in describing the shape of the yield surface and its proven ability to predict the mechanical behavior of sands, the most commercially viable hydrate reservoirs. The model considers MHBS as a deformable elastoplastic continuum, and hydrate-related changes in the stress-strain behavior are predicted by a densification mechanism. The densification attributes the mechanical contribution of hydrate to; a reduction of the available void ratio; a decrease of the swelling line slope; and an increase of the volumetric yield stress. It is described by experimentally derived physical parameters except from the swelling slope coefficient that requires empirical calibration. The Hydrate-CASM is validated against published triaxial laboratory tests performed at different confinement stresses, hydrate saturations, and hydrate morphologies. During the validation, we focused on capturing the mechanical behavior of the host sediment and consider perturbations of the sediment's mechanical properties that could result from the sample preparation. Our model successfully captures the experimentally observed influence of hydrate saturation in the magnitude and trend of the stiffness, shear strength, and dilatancy of MHBS. Hence, we propose that hydrate-related densification changes might be a major factor controlling the geomechanical response of MHBS.

Calcium silicate-based sealers: Assessment of physicochemical properties, porosity and hydration.

Science.gov (United States)

Marciano, Marina Angélica; Duarte, Marco Antonio Hungaro; Camilleri, Josette

2016-02-01

Investigation of hydration, chemical, physical properties and porosity of experimental calcium silicate-based sealers. Experimental calcium silicate-based sealers with calcium tungstate and zirconium oxide radio-opacifiers were prepared by mixing 1g of powder to 0.3 mL of 80% distilled water and 20% propylene glycol. MTA and MTA Fillapex were used as controls. The raw materials and set sealers were characterized using a combination of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Physical properties were analyzed according to ANSI/ADA. The pH and calcium ion release were assessed after 3, 24, 72 and 168 h. The porosity was assessed using mercury intrusion porosimetry. The analysis of hydration of prototype sealers revealed calcium hydroxide as a by-product resulting in alkaline pH and detection of calcium ion release, with high values in initial periods. The radiopacity was similar to MTA for the sealers containing high amounts of radio-opacifiers (p>0.05). Flowability was higher and film thickness was lower for resinous MTA Fillapex sealer (p0.05). The prototype sealers presented adequate hydration, elevated pH and calcium ion release. Regarding physical properties, elevated proportions of radio-opacifiers were necessary to accomplish adequate radiopacity, enhance flowability and reduce film thickness. All the tested sealers presented water sorption and porosity similar to MTA. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Calcium Aluminate Cement Hydration Model

Directory of Open Access Journals (Sweden)

Matusinović, T.

2011-01-01

Full Text Available Calcium aluminate cement (AC is a very versatile special cement used for specific applications. As the hydration of AC is highly temperature dependent, yielding structurally different hydration products that continuously alter material properties, a good knowledge of thermal properties at early stages of hydration is essential. The kinetics of AC hydration is a complex process and the use of single mechanisms models cannot describe the rate of hydration during the whole stage.This paper examines the influence of temperature (ϑ=5–20 °C and water-to-cement mass ratio (mH /mAC = 0.4; 0.5 and 1.0 on hydration of commercial iron-rich AC ISTRA 40 (producer: Istra Cement, Pula, Croatia, which is a part of CALUCEM group, Figs 1–3. The flow rate of heat generation of cement pastes as a result of the hydration reactions was measured with differential microcalorimeter. Chemically bonded water in the hydrated cement samples was determined by thermo-gravimetry.Far less heat is liberated when cement and water come in contact for the first time, Fig. 1, than in the case for portland cement (PC. Higher water-to-cement ratio increases the heat evolved at later ages (Fig. 3 due to higher quantity of water available for hydration. A significant effect of the water-to-cement ratio on the hydration rate and hydration degree showed the importance of water as being the limiting reactant that slows down the reaction early. A simplified stoichiometric model of early age AC hydration (eq. (8 based on reaction schemes of principal minerals, nominally CA, C12A7 and C4AF (Table 1, was employed. Hydration kinetics after the induction period (ϑ < 20 °C had been successfully described (Fig. 4 and Table 2 by a proposed model (eq. (23 which simultaneously comprised three main mechanisms: nucleation and growth, interaction at phase boundary, and mass transfer. In the proposed kinetic model the nucleation and growth is proportional to the amount of reacted minerals (eq

Estimation of Membrane Hydration Status for Standby Proton Exchange Membrane Fuel Cell Systems by Impedance Measurement: First Results on Stack Characterization

DEFF Research Database (Denmark)

Bidoggia, Benoit; Kær, Søren Knudsen

Fuel cells have started replacing traditional lead-acid battery banks in backup systems. Although these systems are characterized by long periods of standby, they must be able to start at any instant in the shortest time. In the case of low temperature proton exchange membrane fuel cell systems......, a precise estimation of hydration status of the fuel cell during standby is important for a fast and safe startup. In this article, the measurement of the complex impedance of the fuel cell is suggested as a method to estimate the membrane hydration status. A 56-cell fuel cell stack has been symmetrically...... fed with air whose temperature and relative humidity were controlled, and its complex impedance was measured at different frequencies and for different values of relative humidity. After showing that the experiment was repeatable, the fuel cell stack was characterized, a power regression model...

X-ray Characterization of Materials

Science.gov (United States)

Lifshin, Eric

1999-09-01

Linking of materials properties with microstructures is a fundamental theme in materials science, for which a detailed knowledge of the modern characterization techniques is essential. Since modern materials such as high-temperature alloys, engineering thermoplastics and multilayer semiconductor films have many elemental constituents distributed in more than one phase, characterization is essential to the systematic development of such new materials and understanding how they behave in practical applications. X-ray techniques play a major role in providing information on the elemental composition and crystal and grain structures of all types of materials. The challenge to the materials characterization expert is to understand how specific instruments and analytical techniques can provide detailed information about what makes each material unique. The challenge to the materials scientist, chemist, or engineer is to know what information is needed to fully characterize each material and how to use this information to explain its behavior, develop new and improved properties, reduce costs, or ensure compliance with regulatory requirements. This comprehensive handbook presents all the necessary background to understand the applications of X-ray analysis to materials characterization with particular attention to the modern approach to these methods.

Advanced Gas Hydrate Reservoir Modeling Using Rock Physics

Energy Technology Data Exchange (ETDEWEB)

McConnell, Daniel

2017-12-30

Prospecting for high saturation gas hydrate deposits can be greatly aided with improved approaches to seismic interpretation and especially if sets of seismic attributes can be shown as diagnostic or direct hydrocarbon indicators for high saturation gas hydrates in sands that would be of most interest for gas hydrate production.

A large 3D seismic data set in the deep water Eastern Gulf of Mexico was screened for gas hydrates using a set of techniques and seismic signatures that were developed and proven in the Central deepwater Gulf of Mexico in the DOE Gulf of Mexico Joint Industry Project JIP Leg II in 2009 and recently confirmed with coring in 2017.

A large gas hydrate deposit is interpreted in the data where gas has migrated from one of the few deep seated faults plumbing the Jurassic hydrocarbon source into the gas hydrate stability zone. The gas hydrate deposit lies within a flat-lying within Pliocene Mississippi Fan channel that was deposited outboard in a deep abyssal environment. The uniform architecture of the channel aided the evaluation of a set of seismic attributes that relate to attenuation and thin-bed energy that could be diagnostic of gas hydrates. Frequency attributes derived from spectral decomposition also proved to be direct hydrocarbon indicators by pseudo-thickness that could be only be reconciled by substituting gas hydrate in the pore space. The study emphasizes that gas hydrate exploration and reservoir characterization benefits from a seismic thin bed approach.

DuraLith geopolymer waste form for Hanford secondary waste: Correlating setting behavior to hydration heat evolution

International Nuclear Information System (INIS)

Xu, Hui; Gong, Weiliang; Syltebo, Larry; Lutze, Werner; Pegg, Ian L.

2014-01-01

Highlights: • Quantitative correlations firstly established for cementitious waste forms. • Quantitative correlations firstly established for geopolymeric materials. • Ternary DuraLith geopolymer waste forms for Hanford radioactive wastes. • Extended setting times which improve workability for geopolymer waste forms. • Reduced hydration heat release from DuraLith geopolymer waste forms. - Abstract: The binary furnace slag-metakaolin DuraLith geopolymer waste form, which has been considered as one of the candidate waste forms for immobilization of certain Hanford secondary wastes (HSW) from the vitrification of nuclear wastes at the Hanford Site, Washington, was extended to a ternary fly ash-furnace slag-metakaolin system to improve workability, reduce hydration heat, and evaluate high HSW waste loading. A concentrated HSW simulant, consisting of more than 20 chemicals with a sodium concentration of 5 mol/L, was employed to prepare the alkaline activating solution. Fly ash was incorporated at up to 60 wt% into the binder materials, whereas metakaolin was kept constant at 26 wt%. The fresh waste form pastes were subjected to isothermal calorimetry and setting time measurement, and the cured samples were further characterized by compressive strength and TCLP leach tests. This study has firstly established quantitative linear relationships between both initial and final setting times and hydration heat, which were never discovered in scientific literature for any cementitious waste form or geopolymeric material. The successful establishment of the correlations between setting times and hydration heat may make it possible to efficiently design and optimize cementitious waste forms and industrial wastes based geopolymers using limited testing results

First-principles elasticity of monocarboaluminate hydrates

KAUST Repository

Moon, J.; Yoon, S.; Wentzcovitch, R. M.; Monteiro, P. J. M.

2014-01-01

The elasticity of monocarboaluminate hydrates, 3CaO·Al2O3·CaCO3·xH2O (x = 11 or 8), has been investigated by first-principles calculations. Previous experimental study revealed that the fully hydrated monocarboaluminate (x = 11) exhibits exceptionally low compressibility compared to other reported calcium aluminate hydrates. This stiff hydration product can contribute to the strength of concrete made with Portland cements containing calcium carbonates. In this study, full elastic tensors and mechanical properties of the crystal structures with different water contents (x = 11 or 8) are computed by first-principles methods based on density functional theory. The results indicate that the compressibility of monocarboaluminate is highly dependent on the water content in the interlayer region. The structure also becomes more isotropic with the addition of water molecules in this region. Since the monocarboaluminate is a key hydration product of limestone added cement, elasticity of the crystal is important to understand its mechanical impact on concrete. Besides, it is put forth that this theoretical calculation will be useful in predicting the elastic properties of other complex cementitous materials and the influence of ion exchange on compressibility.

First-principles elasticity of monocarboaluminate hydrates

KAUST Repository

Moon, J.

2014-07-01

The elasticity of monocarboaluminate hydrates, 3CaO·Al2O3·CaCO3·xH2O (x = 11 or 8), has been investigated by first-principles calculations. Previous experimental study revealed that the fully hydrated monocarboaluminate (x = 11) exhibits exceptionally low compressibility compared to other reported calcium aluminate hydrates. This stiff hydration product can contribute to the strength of concrete made with Portland cements containing calcium carbonates. In this study, full elastic tensors and mechanical properties of the crystal structures with different water contents (x = 11 or 8) are computed by first-principles methods based on density functional theory. The results indicate that the compressibility of monocarboaluminate is highly dependent on the water content in the interlayer region. The structure also becomes more isotropic with the addition of water molecules in this region. Since the monocarboaluminate is a key hydration product of limestone added cement, elasticity of the crystal is important to understand its mechanical impact on concrete. Besides, it is put forth that this theoretical calculation will be useful in predicting the elastic properties of other complex cementitous materials and the influence of ion exchange on compressibility.

Supramolecular Organization of Nonstoichiometric Drug Hydrates: Dapsone

Directory of Open Access Journals (Sweden)

Doris E. Braun

2018-02-01

Full Text Available The observed moisture- and temperature dependent transformations of the dapsone (4,4′-diaminodiphenyl sulfone, DDS 0. 33-hydrate were correlated to its structure and the number and strength of the water-DDS intermolecular interactions. A combination of characterization techniques was used, including thermal analysis (hot-stage microscopy, differential scanning calorimetry and thermogravimetric analysis, gravimetric moisture sorption/desorption studies and variable humidity powder X-ray diffraction, along with computational modeling (crystal structure prediction and pair-wise intermolecular energy calculations. Depending on the relative humidity the hydrate contains between 0 and 0.33 molecules of water per molecule DDS. The crystal structure is retained upon dehydration indicating that DDS hydrate shows a non-stoichiometric (dehydration behavior. Unexpectedly, the water molecules are not located in structural channels but at isolated-sites of the host framework, which is counterintuitively for a hydrate with non-stoichiometric behavior. The water-DDS interactions were estimated to be weaker than water-host interactions that are commonly observed in stoichiometric hydrates and the lattice energies of the isomorphic dehydration product (hydrate structure without water molecules and (form III differ only by ~1 kJ mol−1. The computational generation of hypothetical monohydrates confirms that the hydrate with the unusual DDS:water ratio of 3:1 is more stable than a feasible monohydrate structure. Overall, this study highlights that a deeper understanding of the formation of hydrates with non-stoichiometric behavior requires a multidisciplinary approach including suitable experimental and computational methods providing a firm basis for the development and manufacturing of high quality drug products.

Methane hydrates in nature - Current knowledge and challenges

Science.gov (United States)

Collett, Timothy S.

2014-01-01

Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance

Characterization of early-age hydration processes in lime-ceramic binders using isothermal calorimetry, X-ray diffraction and scanning electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Jerman, Miloš; Tydlitát, Vratislav; Keppert, Martin; Čáchová, Monika; Černý, Robert, E-mail: cernyr@fsv.cvut.cz

2016-06-10

Highlights: • Early age hydration processes in lime-ceramic binders are analyzed within a wide range of component ratios. • The applied waste ceramic dust exhibits partial hydraulic properties, ettringite and calcite are formed. • Transition from tobermorite- to jennite-like structures is identified by SEM within the first 48 h. • The highest specific hydration heat after 300 h, 63 J/g, is measured for the binder containing 70% ceramic. • Substantial effect of the heat of wetting is observed, ranging from 10 J/g for lime to 3.9 J/g for ceramic. - Abstract: Early-age hydration processes in a lime-ceramic-water system are analyzed within the whole range of possible lime/ceramic ratios. The isothermal calorimetry shows a substantial effect of the heat of wetting on the total heat evolved, ranging from 10 J/g for lime to 3.9 J/g for ceramic. The highest specific hydration heat of 63 J/g during the analyzed 300-h hydration period exhibits the blended binder containing 70% ceramic and 30% lime which correlates well with the highest compressive and bending strengths of the paste prepared using this blend. Portlandite, ettringite and calcite are the main phases identified by the X-ray diffraction analysis after the hydration of ceramic-rich blends. According to the results of scanning electron microscopy, the initial course of pozzolanic reaction is for this type of binders characterized by the transition from tobermorite-like calcium-silicate-hydrate structures into jennite-like structures within the first 48 h. Blends with the ceramic content lower than 70% show a high portion of portlandite, calcite is present in low amount, and the jennite-like structures are observed after 48 h, following the initial formation of components with a very high Ca content. The favorable properties of the ceramic-rich blended binders can be explained by the partial hydraulic character of the ceramic. With the specific hydration heat of 29 J/g after 300 h and compressive strength

Characterization of early-age hydration processes in lime-ceramic binders using isothermal calorimetry, X-ray diffraction and scanning electron microscopy

International Nuclear Information System (INIS)

Jerman, Miloš; Tydlitát, Vratislav; Keppert, Martin; Čáchová, Monika; Černý, Robert

2016-01-01

Highlights: • Early age hydration processes in lime-ceramic binders are analyzed within a wide range of component ratios. • The applied waste ceramic dust exhibits partial hydraulic properties, ettringite and calcite are formed. • Transition from tobermorite- to jennite-like structures is identified by SEM within the first 48 h. • The highest specific hydration heat after 300 h, 63 J/g, is measured for the binder containing 70% ceramic. • Substantial effect of the heat of wetting is observed, ranging from 10 J/g for lime to 3.9 J/g for ceramic. - Abstract: Early-age hydration processes in a lime-ceramic-water system are analyzed within the whole range of possible lime/ceramic ratios. The isothermal calorimetry shows a substantial effect of the heat of wetting on the total heat evolved, ranging from 10 J/g for lime to 3.9 J/g for ceramic. The highest specific hydration heat of 63 J/g during the analyzed 300-h hydration period exhibits the blended binder containing 70% ceramic and 30% lime which correlates well with the highest compressive and bending strengths of the paste prepared using this blend. Portlandite, ettringite and calcite are the main phases identified by the X-ray diffraction analysis after the hydration of ceramic-rich blends. According to the results of scanning electron microscopy, the initial course of pozzolanic reaction is for this type of binders characterized by the transition from tobermorite-like calcium-silicate-hydrate structures into jennite-like structures within the first 48 h. Blends with the ceramic content lower than 70% show a high portion of portlandite, calcite is present in low amount, and the jennite-like structures are observed after 48 h, following the initial formation of components with a very high Ca content. The favorable properties of the ceramic-rich blended binders can be explained by the partial hydraulic character of the ceramic. With the specific hydration heat of 29 J/g after 300 h and compressive strength

Origins of saccharide-dependent hydration at aluminate, silicate, and aluminosilicate surfaces.

Science.gov (United States)

Smith, Benjamin J; Rawal, Aditya; Funkhouser, Gary P; Roberts, Lawrence R; Gupta, Vijay; Israelachvili, Jacob N; Chmelka, Bradley F

2011-05-31

Sugar molecules adsorbed at hydrated inorganic oxide surfaces occur ubiquitously in nature and in technologically important materials and processes, including marine biomineralization, cement hydration, corrosion inhibition, bioadhesion, and bone resorption. Among these examples, surprisingly diverse hydration behaviors are observed for oxides in the presence of saccharides with closely related compositions and structures. Glucose, sucrose, and maltodextrin, for example, exhibit significant differences in their adsorption selectivities and alkaline reaction properties on hydrating aluminate, silicate, and aluminosilicate surfaces that are shown to be due to the molecular architectures of the saccharides. Solid-state (1)H, (13)C, (29)Si, and (27)Al nuclear magnetic resonance (NMR) spectroscopy measurements, including at very high magnetic fields (19 T), distinguish and quantify the different molecular species, their chemical transformations, and their site-specific adsorption on different aluminate and silicate moieties. Two-dimensional NMR results establish nonselective adsorption of glucose degradation products containing carboxylic acids on both hydrated silicates and aluminates. In contrast, sucrose adsorbs intact at hydrated silicate sites and selectively at anhydrous, but not hydrated, aluminate moieties. Quantitative surface force measurements establish that sucrose adsorbs strongly as multilayers on hydrated aluminosilicate surfaces. The molecular structures and physicochemical properties of the saccharides and their degradation species correlate well with their adsorption behaviors. The results explain the dramatically different effects that small amounts of different types of sugars have on the rates at which aluminate, silicate, and aluminosilicate species hydrate, with important implications for diverse materials and applications.

Effects of Attenuation of Gas Hydrate-bearing Sediments on Seismic Data: Example from Mallik, Northwest Territories, Canada

Science.gov (United States)

Bellefleur, G.; Riedel, M.; Brent, T.

2007-05-01

Wave attenuation is an important physical property of hydrate-bearing sediments that is rarely taken into account in site characterization with seismic data. We present a field example showing improved images of hydrate- bearing sediments on seismic data after compensation of attenuation effects. Compressional quality factors (Q) are estimated from zero-offset Vertical Seismic Profiling data acquired at Mallik, Northwest Territories, Canada. During the last 10 years, two internationally-partnered research drilling programs have intersected three major intervals of sub-permafrost gas hydrates at Mallik, and have successfully extracted core samples containing significant amount of gas hydrates. Individual gas hydrate intervals are up to 40m in thickness and are characterized by high in situ gas hydrate saturation, sometimes exceeding 80% of pore volume of unconsolidated clastic sediments having average porosities ranging from 25% to 40%. The Q-factors obtained from the VSP data demonstrate significant wave attenuation for permafrost and hydrate- bearing sediments. These results are in agreement with previous attenuation estimates from sonic logs and crosshole data at different frequency intervals. The Q-factors obtained from VSP data were used to compensate attenuation effects on surface 3D seismic data acquired over the Mallik gas hydrate research wells. Intervals of gas hydrate on surface seismic data are characterized by strong reflectivity and effects from attenuation are not perceptible from a simple visual inspection of the data. However, the application of an inverse Q-filter increases the resolution of the data and improves correlation with log data, particularly for the shallowest gas hydrate interval. Compensation of the attenuation effects of the permafrost likely explains most of the improvements for the shallow gas hydrate zone. Our results show that characterization of the Mallik gas hydrates with seismic data not corrected for attenuation would tend to

Results at Mallik highlight progress in gas hydrate energy resource research and development

Science.gov (United States)

Collett, T.S.

2005-01-01

The recent studies that project the role of gas hydrates in the future energy resource management are reviewed. Researchers have long speculated that gas hydrates could eventually be a commercial resource for the future. A Joint Industry Project led by ChevronTexaco and the US Department of Energy is designed to characterize gas hydrates in the Gulf of Mexico. Countries including Japan, canada, and India have established large gas hydrate research and development projects, while China, Korea and Mexico are investigating the viability of forming government-sponsored gas hydrate research projects.

Correlations between skin hydration parameters and corneocyte-derived parameters to characterize skin conditions.

Science.gov (United States)

Masaki, Hitoshi; Yamashita, Yuki; Kyotani, Daiki; Honda, Tatsuya; Takano, Kenichi; Tamura, Toshiyasu; Mizutani, Taeko; Okano, Yuri

2018-03-30

Skin hydration is generally assessed using the parameters of skin surface water content (SWC) and trans-epidermal water loss (TEWL). To date, few studies have characterized skin conditions using correlations between skin hydration parameters and corneocyte parameters. The parameters SWC and TEWL allow the classification of skin conditions into four distinct Groups. The purpose of this study was to assess the characteristics of skin conditions classified by SWC and TEWL for correlations with parameters from corneocytes. A human volunteer test was conducted that measured SWC and TEWL. As corneocyte-derived parameters, the size and thick abrasion ratios, the ratio of sulfhydryl groups and disulfide bonds (SH/SS) and CP levels were analyzed. Volunteers were classified by their median SWC and TEWL values into 4 Groups: Group I (high SWC/low TEWL), Group II (high SWC/high TEWL), Group III (low SWC/low TEWL), and Group IV (low SWC/high TEWL). Group IV showed a significantly smaller size of corneocytes. Groups III and IV had significantly higher thick abrasion ratios and CP levels. Group I had a significantly lower SH/SS value. The SWC/TEWL value showed a decline in order from Group I to Group IV. Groups classified by their SWC and TEWL values showed characteristic skin conditions. We propose that the SWC and TEWL ratio is a comprehensive parameter to assess skin conditions. © 2018 Wiley Periodicals, Inc.

Halogen systematics in the Mallik 5L-38 gas hydrate production research well, Northwest Territories, Canada: Implications for the origin of gas hydrates under terrestrial permafrost conditions

International Nuclear Information System (INIS)

Tomaru, Hitoshi; Fehn, Udo; Lu, Zunli; Matsumoto, Ryo

2007-01-01

The authors report here halogen concentrations in pore waters and sediments collected from the Mallik 5L-38 gas hydrate production research well, a permafrost location in the Mackenzie Delta, Northwest Territories, Canada. Iodine and Br are commonly enriched in waters associated with CH 4 , reflecting the close association between these halogens and source organic materials. Pore waters collected from the Mallik well show I enrichment, by one order of magnitude above that of seawater, particularly in sandy layers below the gas hydrate stability zone (GHSZ). Although Cl and Br concentrations increase with depth similar to the I profile, they remain below seawater values. The increase in I concentrations observed below the GHSZ suggests that I-rich fluids responsible for the accumulation of CH 4 in gas hydrates are preferentially transported through the sandy permeable layers below the GHSZ. The Br and I concentrations and I/Br ratios in Mallik are considerably lower than those in marine gas hydrate locations, demonstrating a terrestrial nature for the organic materials responsible for the CH 4 at the Mallik site. Halogen systematics in Mallik suggest that they are the result of mixing between seawater, freshwater and an I-rich source fluid. The comparison between I/Br ratios in pore waters and sediments speaks against the origin of the source fluids within the host formations of gas hydrates, a finding compatible with the results from a limited set of 129 I/I ratios determined in pore waters, which gives a minimum age of 29 Ma for the source material, i.e. at the lower end of the age range of the host formations. The likely scenario for the gas hydrate formation in Mallik is the derivation of CH 4 together with I from the terrestrial source materials in formations other than the host layers through sandy permeable layers into the present gas hydrate zones

Preparation and Thermal Properties of Eutectic Hydrate Salt Phase Change Thermal Energy Storage Material

OpenAIRE

Liang, Lin; Chen, Xi

2018-01-01

In this study, a new cold storage phase change material eutectic hydrate salt (K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O) was prepared, modified, and tested. The modification was performed by adding a nucleating agent and thickener. The physical properties such as viscosity, surface tension, cold storage characteristics, supercooling, and the stability during freeze-thaw cycles were studied. Results show that the use of nucleating agents, such as sodium tetraborate, sodium fluoride, and nanoparti...

Structural determinants of hydration, mechanics and fluid flow in freeze-dried collagen scaffolds.

Science.gov (United States)

Offeddu, G S; Ashworth, J C; Cameron, R E; Oyen, M L

2016-09-01

Freeze-dried scaffolds provide regeneration templates for a wide range of tissues, due to their flexibility in physical and biological properties. Control of structure is crucial for tuning such properties, and therefore scaffold functionality. However, the common approach of modeling these scaffolds as open-cell foams does not fully account for their structural complexity. Here, the validity of the open-cell model is examined across a range of physical characteristics, rigorously linking morphology to hydration and mechanical properties. Collagen scaffolds with systematic changes in relative density were characterized using Scanning Electron Microscopy, X-ray Micro-Computed Tomography and spherical indentation analyzed in a time-dependent poroelastic framework. Morphologically, all scaffolds were mid-way between the open- and closed-cell models, approaching the closed-cell model as relative density increased. Although pore size remained constant, transport pathway diameter decreased. Larger collagen fractions also produced greater volume swelling on hydration, although the change in pore diameter was constant, and relatively small at ∼6%. Mechanically, the dry and hydrated scaffold moduli varied quadratically with relative density, as expected of open-cell materials. However, the increasing pore wall closure was found to determine the time-dependent nature of the hydrated scaffold response, with a decrease in permeability producing increasingly elastic rather than viscoelastic behavior. These results demonstrate that characterizing the deviation from the open-cell model is vital to gain a full understanding of scaffold biophysical properties, and provide a template for structural studies of other freeze-dried biomaterials. Freeze-dried collagen sponges are three-dimensional microporous scaffolds that have been used for a number of exploratory tissue engineering applications. The characterization of the structure-properties relationships of these scaffolds is

Studies of ancient concrete as analogs of cementitious sealing materials for a repository in tuff

Energy Technology Data Exchange (ETDEWEB)

Roy, D.M.; Langton, C.A.

1989-03-01

The durability of ancient cementitious materials has been investigated to provide data applicable to determining the resistance to weathering of concrete materials for sealing a repository for storage of high-level radioactive waste. Because tuff and volcanic ash are used in the concretes in the vicinity of Rome, the results are especially applicable to a waste repository in tuff. Ancient mortars, plasters, and concretes collected from Rome, Ostia, and Cosa dating to the third century BC show remarkable durability. The aggregates used in the mortars, plasters, and concretes included basic volcanic and pyroclastic rocks (including tuff), terra-cotta, carbonates, sands, and volcanic ash. The matrices of ancient cementitious materials have been characterized and classified into four categories: (1) hydraulic hydrated lime and hydrated lime cements, (2) hydraulic aluminous and ferruginous hydrated lime cements ({plus_minus} siliceous components), (3) pozzolana/hydrated lime cements, and (4) gypsum cements. Most of the materials investigated are in category (3). The materials were characterized to elucidate aspects of the technology that produced them and their response to the environmental exposure throughout their centuries of existence. Their remarkable properties are the result of a combination of chemical, mineralogical, and microstructural factors. Their durability was found to be affected by the matrix mineralogy, particle size, and porosity; aggregate type, grading and proportioning; and the methodology of placement. 30 refs.

Gas hydrate inhibition by perturbation of liquid water structure

Science.gov (United States)

Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Lee, Kun-Hong

2015-06-01

Natural gas hydrates are icy crystalline materials that contain hydrocarbons, which are the primary energy source for this civilization. The abundance of naturally occurring gas hydrates leads to a growing interest in exploitation. Despite their potential as energy resources and in industrial applications, there is insufficient understanding of hydrate kinetics, which hinders the utilization of these invaluable resources. Perturbation of liquid water structure by solutes has been proposed to be a key process in hydrate inhibition, but this hypothesis remains unproven. Here, we report the direct observation of the perturbation of the liquid water structure induced by amino acids using polarized Raman spectroscopy, and its influence on gas hydrate nucleation and growth kinetics. Amino acids with hydrophilic and/or electrically charged side chains disrupted the water structure and thus provided effective hydrate inhibition. The strong correlation between the extent of perturbation by amino acids and their inhibition performance constitutes convincing evidence for the perturbation inhibition mechanism. The present findings bring the practical applications of gas hydrates significantly closer, and provide a new perspective on the freezing and melting phenomena of naturally occurring gas hydrates.

Precise structural analysis of methane hydrate by neutron diffraction

International Nuclear Information System (INIS)

Igawa, Naoki; Hoshikawa, Akinori; Ishii, Yoshinobu

2006-01-01

Methane hydrate has attracted great interest as an energy resource to replace natural gas since this material is deposited in the seafloor and the deposits are estimated to exceed those of natural gas. Understanding the physical proprieties, such as the temperature dependence of the crystal structure, helps to specify the optimum environmental temperature and pressure during drilling, transport, and storage of methane hydrate. Clathrate hydrates consisted of encaging atomic and/or molecular species as a guest and host water formed by a hydrogen bonding. Although many studies on the clathrate hydrate including methane hydrate were reported, no detailed crystallographic property has yet been cleared. We focused on the motion of methane in the clathrate hydrate by the neutron diffraction. The crystal structure of the methane hydrate was analyzed by the applying the combination of the Rietveld refinement and the maximum entropy method (MEM) to neutron powder diffraction. Temperature dependence of the scattering-length density distribution maps revealed that the motion of methane molecules differs between the shapes of dodecahedron and tetrakaidecahedron. (author)

Characterization of phase change materials for thermal control of photovoltaics using Differential Scanning Calorimetry and Temperature History Method

International Nuclear Information System (INIS)

Hasan, A.; McCormack, S.J.; Huang, M.J.; Norton, B.

2014-01-01

Highlights: • Five PCM are characterized using tow techniques for PV temperature regulation. • Thermophysical properties of interest are determined and compared with literature. • Determined PCM properties are discussed as criteria for PV temperature regulation. • One PCM identified as potential candidate for PV temperature regulation. - Abstract: Five solid–liquid phase change materials comprising three basic classes, paraffin waxes, salt hydrates and mixtures of fatty acids were thermophysically characterized for thermal regulation applications in photovoltaics. The PCM were investigated using Differential Scanning Calorimetry and Temperature History Method to find their thermophysical properties of interest. The relationship between thermophysical properties of the PCM and their choice as temperature regulators in photovoltaics is discussed in relation to the ambient conditions under which PV systems operate

Characterization of minerals, metals and materials

CERN Document Server

Hwang, Jiann-Yang; Bai, Chengguang; Carpenter, John; Cai, Mingdong; Firrao, Donato; Kim, Byoung-Gon

2012-01-01

This state-of-the-art reference contains chapters on all aspects of the characterization of minerals, metals, and materials. The title presents papers from one of the largest yearly gatherings of materials scientists in the world and thoroughly discusses the characterization of minerals, metals, and materials The scope includes current industrial applications and research and developments in the following areas:  Characterization of Ferrous Metals Characterization of Non-Ferrous Materials Characterization of Minerals and Ceramics Character

Hydration-coupled protein boson peak measured by incoherent neutron scattering

International Nuclear Information System (INIS)

Nakagawa, Hiroshi; Kataoka, Mikio; Joti, Yasumasa; Kitao, Akio; Shibata, Kaoru; Tokuhisa, Atsushi; Tsukushi, Itaru; Go, Nobuhiro

2006-01-01

The boson peak of a protein was examined in relation to hydration using staphylococcal nuclease. Although the boson peak is commonly observed in synthetic polymers, glassy materials and amorphous materials, the origin of the boson peak is not fully understood. The motions that contribute to the peak are harmonic vibrations. Upon hydration the peak frequency shifts to a higher frequency and the effective force constant of the vibration increases at low temperatures, suggesting that the protein energy surface is modified. Hydration of the protein leads to a more rugged surface and the vibrational motions are trapped within the local minimum at cryogenic temperatures. The origin of the protein boson peak may be related to this rugged energy surface

Three types of gas hydrate reservoirs in the Gulf of Mexico identified in LWD data

Science.gov (United States)

Lee, Myung Woong; Collett, Timothy S.

2011-01-01

High quality logging-while-drilling (LWD) well logs were acquired in seven wells drilled during the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II in the spring of 2009. These data help to identify three distinct types of gas hydrate reservoirs: isotropic reservoirs in sands, vertical fractured reservoirs in shale, and horizontally layered reservoirs in silty shale. In general, most gas hydratebearing sand reservoirs exhibit isotropic elastic velocities and formation resistivities, and gas hydrate saturations estimated from the P-wave velocity agree well with those from the resistivity. However, in highly gas hydrate-saturated sands, resistivity-derived gas hydrate-saturation estimates appear to be systematically higher by about 5% over those estimated by P-wave velocity, possibly because of the uncertainty associated with the consolidation state of gas hydrate-bearing sands. Small quantities of gas hydrate were observed in vertical fractures in shale. These occurrences are characterized by high formation resistivities with P-wave velocities close to those of water-saturated sediment. Because the formation factor varies significantly with respect to the gas hydrate saturation for vertical fractures at low saturations, an isotropic analysis of formation factor highly overestimates the gas hydrate saturation. Small quantities of gas hydrate in horizontal layers in shale are characterized by moderate increase in P-wave velocities and formation resistivities and either measurement can be used to estimate gas hydrate saturations.

Dehydration behaviour of hydrates

Energy Technology Data Exchange (ETDEWEB)

Dette, S.S.; Stelzer, T.; Jones, M.J.; Ulrich, J. [Martin-Luther-Universitaet Halle-Wittenberg, Zentrum fuer Ingenieurwissenschaften, Verfahrenstechnik/TVT, 06099 Halle (Germany)

2010-07-15

Immersing a crystalline solvate in a suitable anti-solvent can induce phase transformation to solvent-free solid phase. In certain cases the solvent-mediated phase transition results in the generation of hollow, tubular structures. Both the tube dimensions of sodium-2-keto-L-gulonate anhydrate (skga) and the dehydration kinetics of sodium-2-keto-L-gulonate monohydrate (skgm) can be modified by the antisolvent employed. An explanation for the variable dehydration behaviour of skgm in the antisolvents is presented here. Furthermore, other crystalline hydrates were dehydrated in dry methanol. Providing an operational window can be found, any hydrate material could possibly find use in the production of tubes (micro- or nanotubes for different applications). The experimental conditions selected (dry methanol as antisolvent, dehydration temperature at 25 C) for the dehydration did not lead to the anhydrate tube growth for all hydrates investigated. Based upon the results presented here a first hypothesis is presented to explain this effect. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Characterization of proton exchange membrane materials for fuel cells by solid state nuclear magnetic resonance

Energy Technology Data Exchange (ETDEWEB)

Kong, Zueqian [Iowa State Univ., Ames, IA (United States)

2010-01-01

Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-angle X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that only the water channel model gives the measured S/V ratios in the normal hydration range of a working fuel cell, while dispersed water molecules and polymer ribbons account for the structures at low and high hydration levels, respectively.

Optimization of linear and branched alkane interactions with water to simulate hydrophobic hydration

Science.gov (United States)

Ashbaugh, Henry S.; Liu, Lixin; Surampudi, Lalitanand N.

2011-08-01

Previous studies of simple gas hydration have demonstrated that the accuracy of molecular simulations at capturing the thermodynamic signatures of hydrophobic hydration is linked both to the fidelity of the water model at replicating the experimental liquid density at ambient pressure and an accounting of polarization interactions between the solute and water. We extend those studies to examine alkane hydration using the transferable potentials for phase equilibria united-atom model for linear and branched alkanes, developed to reproduce alkane phase behavior, and the TIP4P/2005 model for water, which provides one of the best descriptions of liquid water for the available fixed-point charge models. Alkane site/water oxygen Lennard-Jones cross interactions were optimized to reproduce the experimental alkane hydration free energies over a range of temperatures. The optimized model reproduces the hydration free energies of the fitted alkanes with a root mean square difference between simulation and experiment of 0.06 kcal/mol over a wide temperature range, compared to 0.44 kcal/mol for the parent model. The optimized model accurately reproduces the temperature dependence of hydrophobic hydration, as characterized by the hydration enthalpies, entropies, and heat capacities, as well as the pressure response, as characterized by partial molar volumes.

Instrumented Pressure Testing Chamber (IPTC) Characterization of Methane Gas Hydrate-Bearing Pressure Cores Collected from the Methane Production Test Site in the Eastern Nankai Trough, Offshore Japan

Science.gov (United States)

Waite, W. F.; Santamarina, J. C.; Dai, S.; Winters, W. J.; Yoneda, J.; Konno, Y.; Nagao, J.; Suzuki, K.; Fujii, T.; Mason, D. H.; Bergeron, E.

2014-12-01

Pressure cores obtained at the Daini-Atsumi Knoll in the eastern Nankai Trough, the site of the methane hydrate production test completed by the Methane Hydrate Resources in Japan (MH21) project in March 2013, were recovered from ~300 meters beneath the sea floor at close to in situ pressure. Cores were subsequently stored at ~20 MPa and ~5°C, which maintained hydrate in the cores within stability conditions. Pressure core physical properties were measured at 10 MPa and ~6°C, also within the methane hydrate stability field, using the IPTC and other Pressure Core Characterization Tools (PCCTs). Discrete IPTC measurements were carried out in strata ranging from silty sands to clayey silts within the turbidite sequences recovered in the cores. As expected, hydrate saturations were greatest in more permeable coarser-grained layers. Key results include: 1) Where hydrate saturation exceeded 40% in sandy sediments, the gas hydrate binds sediment grains within the matrix. The pressure core analyses yielded nearly in situ mechanical properties despite the absence of effective stress in the IPTC. 2) In adjacent fine-grained sediment (hydrate saturation < 15%), hydrate did not significantly bind the sediment. IPTC results in these locations were consistent with the zero effective-stress limit of comparable measurements made in PCCT devices that are designed to restore the specimen's in situ effective stress. In sand-rich intervals with high gas hydrate saturations, the measured compressional and shear wave velocities suggest that hydrate acts as a homogeneously-distributed, load-bearing member of the bulk sediment. The sands with high gas hydrate saturations were prone to fracturing (brittle failure) during insertion of the cone penetrometer and electrical conductivity probes. Authors would like to express their sincere appreciation to MH21 and the Ministry of Economy, Trade and Industry for permitting this work to be disclosed at the 2014 Fall AGU meeting.

Micro- and nano-scale characterization to study the thermal degradation of cement-based materials

International Nuclear Information System (INIS)

Lim, Seungmin; Mondal, Paramita

2014-01-01

The degradation of hydration products of cement is known to cause changes in the micro- and nano-structure, which ultimately drive thermo-mechanical degradation of cement-based composite materials at elevated temperatures. However, a detailed characterization of these changes is still incomplete. This paper presents results of an extensive experimental study carried out to investigate micro- and nano-structural changes that occur due to exposure of cement paste to high temperatures. Following heat treatment of cement paste up to 1000 °C, damage states were studied by compressive strength test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) atomic force microscopy (AFM) and AFM image analysis. Using experimental results and research from existing literature, new degradation processes that drive the loss of mechanical properties of cement paste are proposed. The development of micro-cracks at the interface between unhydrated cement particles and paste matrix, a change in C–S–H nano-structure and shrinkage of C–S–H, are considered as important factors that cause the thermal degradation of cement paste. - Highlights: • The thermal degradation of hydration products of cement is characterized at micro- and nano-scale using scanning electron microscopy (SEM) and atomic force microscopy (AFM). • The interface between unhydrated cement particles and the paste matrix is considered the origin of micro-cracks. • When cement paste is exposed to temperatures above 300 ºC, the nano-structure of C-S-H becomes a more loosely packed globular structure, which could be indicative of C-S-H shrinkage

Final Scientific/Technical Report: Characterizing the Response of the Cascadia Margin Gas Hydrate Reservoir to Bottom Water Warming Along the Upper Continental Slope

Energy Technology Data Exchange (ETDEWEB)

Solomon, Evan A. [Univ. of Washington, Seattle, WA (United States); Johnson, H. Paul [Univ. of Washington, Seattle, WA (United States); Salmi, Marie [Univ. of Washington, Seattle, WA (United States); Whorley, Theresa [Univ. of Washington, Seattle, WA (United States)

2017-11-10

The objective of this project is to understand the response of the WA margin gas hydrate system to contemporary warming of bottom water along the upper continental slope. Through pre-cruise analysis and modeling of archive and recent geophysical and oceanographic data, we (1) inventoried bottom simulating reflectors along the WA margin and defined the upper limit of gas hydrate stability, (2) refined margin-wide estimates of heat flow and geothermal gradients, (3) characterized decadal scale temporal variations of bottom water temperatures at the upper continental slope of the Washington margin, and (4) used numerical simulations to provide quantitative estimates of how the shallow boundary of methane hydrate stability responds to modern environmental change. These pre-cruise results provided the context for a systematic geophysical and geochemical survey of methane seepage along the upper continental slope from 48° to 46°N during a 10-day field program on the R/V Thompson from October 10-19, 2014. This systematic inventory of methane emissions along this climate-sensitive margin corridor and comprehensive sediment and water column sampling program provided data and samples for Phase 3 of this project that focused on determining fluid and methane sources (deep-source vs. shallow; microbial, thermogenic, gas hydrate dissociation) within the sediment, and how they relate to contemporary intermediate water warming. During the 2014 research expedition, we sampled nine seep sites between ~470 and 520 m water depth, within the zone of predicted methane hydrate retreat over the past 40 years. We imaged 22 bubble plumes with heights commonly rising to ~300 meters below sea level with one reaching near the sea surface. We collected 22 gravity cores and 20 CTD/hydrocasts from the 9 seeps and at background locations (no acoustic evidence of seepage) within the depth interval of predicted downslope retreat of the methane hydrate stability zone. Approximately 300 pore water

A prediction method of natural gas hydrate formation in deepwater gas well and its application

Directory of Open Access Journals (Sweden)

Yanli Guo

2016-09-01

Full Text Available To prevent the deposition of natural gas hydrate in deepwater gas well, the hydrate formation area in wellbore must be predicted. Herein, by comparing four prediction methods of temperature in pipe with field data and comparing five prediction methods of hydrate formation with experiment data, a method based on OLGA & PVTsim for predicting the hydrate formation area in wellbore was proposed. Meanwhile, The hydrate formation under the conditions of steady production, throttling and shut-in was predicted by using this method based on a well data in the South China Sea. The results indicate that the hydrate formation area decreases with the increase of gas production, inhibitor concentrations and the thickness of insulation materials and increases with the increase of thermal conductivity of insulation materials and shutdown time. Throttling effect causes a plunge in temperature and pressure in wellbore, thus leading to an increase of hydrate formation area.

Temporal Characterization of Hydrates System Dynamics beneath Seafloor Mounds. Integrating Time-Lapse Electrical Resistivity Methods and In Situ Observations of Multiple Oceanographic Parameters

Energy Technology Data Exchange (ETDEWEB)

Lutken, Carol [Univ. of Mississippi, Oxford, MS (United States); Macelloni, Leonardo [Univ. of Mississippi, Oxford, MS (United States); D' Emidio, Marco [Univ. of Mississippi, Oxford, MS (United States); Dunbar, John [Univ. of Mississippi, Oxford, MS (United States); Higley, Paul [Univ. of Mississippi, Oxford, MS (United States)

2015-01-31

This study was designed to investigate temporal variations in hydrate system dynamics by measuring changes in volumes of hydrate beneath hydrate-bearing mounds on the continental slope of the northern Gulf of Mexico, the landward extreme of hydrate occurrence in this region. Direct Current Resistivity (DCR) measurements were made contemporaneously with measurements of oceanographic parameters at Woolsey Mound, a carbonate-hydrate complex on the mid-continental slope, where formation and dissociation of hydrates are most vulnerable to variations in oceanographic parameters affected by climate change, and where changes in hydrate stability can readily translate to loss of seafloor stability, impacts to benthic ecosystems, and venting of greenhouse gases to the water-column, and eventually, the atmosphere. We focused our study on hydrate within seafloor mounds because the structurally-focused methane flux at these sites likely causes hydrate formation and dissociation processes to occur at higher rates than at sites where the methane flux is less concentrated and we wanted to maximize our chances of witnessing association/dissociation of hydrates. We selected a particularly well-studied hydrate-bearing seafloor mound near the landward extent of the hydrate stability zone, Woolsey Mound (MC118). This mid-slope site has been studied extensively and the project was able to leverage considerable resources from the team’s research experience at MC118. The site exhibits seafloor features associated with gas expulsion, hydrates have been documented at the seafloor, and changes in the outcropping hydrates have been documented, photographically, to have occurred over a period of months. We conducted observatory-based, in situ measurements to 1) characterize, geophysically, the sub-bottom distribution of hydrate and its temporal variability, and 2) contemporaneously record relevant environmental parameters (temperature, pressure, salinity, turbidity, bottom currents) to

Investigation of C3 S hydration mechanism by transmission electron microscope (TEM) with integrated Super-XTM EDS system.

Science.gov (United States)

Sakalli, Y; Trettin, R

2017-07-01

Tricalciumsilicate (C 3 S, Alite) is the major component of the Portland cement clinker. Hydration of Alite is decisive in influencing the properties of the resulting material. This is due to its high content in cement. The mechanism of the hydration of C 3 S is very complicated and not yet fully understood. There are different models describing the hydration of C 3 S in various ways. In this work for a better understanding of hydration mechanism, the hydrated C 3 S was investigated by using the transmission electron microscope (TEM) and for the first time, the samples for the investigations were prepared by using of focused ion beam from sintered pellets of C 3 S. Also, an FEI Talos F200x with an integrated Super-X EDS system was used for the investigations. FEI Talos F200X combines outstanding high-resolution S/TEM and TEM imaging with energy dispersive X-ray spectroscopy signal detection, and 3D chemical characterization with compositional mapping. TEM is a very powerful tool for material science. A high energy beam of electrons passes through a very thin sample, and the interactions between the electrons and the atoms can be used to observe the structure of the material and other features in the structure. TEM can be used to study the growth of layers and their composition. TEM produces high-resolution, two-dimensional images and will be used for a wide range of educational, science and industry applications. Chemical analysis can also be performed. The purpose of these investigations was to get the information about the composition of the C-S-H phases and some details of the nanostructure of the C-S-H phases. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Textural and mechanical characterization of C-S-H gels from hydration of synthetic T1-C3S, β-C2S and their blends

International Nuclear Information System (INIS)

Goni, S.; Guerrero, A.; Puertas, F.; Hernandez, M. S.; Palacios, M.; Dolado, J. S.; Zhu, W.; Howind, T.

2011-01-01

The textural and mechanical characterization of C-S-H gels formed from the hydration of pure T1-C 3 S, β-C 2 S and their blends are studied by Nitrogen sorption and nano indentation experiments. The surface area and nano porosity of C-S-H gels formed from the hydration of β-C 2 S and the 30-70 (T1-C 3 S and β-C 2 S mixture) are higher than those from hydration of T1-C 3 S, and 70-30, with the difference decreasing with hydration age. Such changes are well supported by findings of nano indentation study, which shows the greater relative volume of C-S-H phases with lower densities in the β-C 2 S and the 30-70 pastes. With the increase in hydration age, the relative volume of C-S-H phases with higher densities increased at the expenses of those with lower density. Important quantitative correlations were found among these textural characteristics and the mean chain length, determined from 2 9Si magic-angle-spinning (MAS) NMR, of the C-S-H gels. (Author) 36 refs.

Nasogastric Hydration in Infants with Bronchiolitis Less Than 2 Months of Age.

Science.gov (United States)

Oakley, Ed; Bata, Sonny; Rengasamy, Sharmila; Krieser, David; Cheek, John; Jachno, Kim; Babl, Franz E

2016-11-01

To determine whether nasogastric hydration can be used in infants less than 2 months of age with bronchiolitis, and characterize the adverse events profile of these infants compared with infants given intravenous (IV) fluid hydration. A descriptive retrospective cohort study of children with bronchiolitis under 2 months of age admitted for hydration at 3 centers over 3 bronchiolitis seasons was done. We determined type of hydration (nasogastric vs IV fluid hydration) and adverse events, intensive care unit admission, and respiratory support. Of 491 infants under 2 months of age admitted with bronchiolitis, 211 (43%) received nonoral hydration: 146 (69%) via nasogastric hydration and 65 (31%) via IV fluid hydration. Adverse events occurred in 27.4% (nasogastric hydration) and 23.1% (IV fluid hydration), difference of 4.3%; 95%CI (-8.2 to 16.9), P = .51. The majority of adverse events were desaturations (21.9% nasogastric hydration vs 21.5% IV fluid hydration, difference 0.4%; [-11.7 to 12.4], P = .95). There were no pulmonary aspirations in either group. Apneas and bradycardias were similar in each group. IV fluid hydration use was positively associated with intensive care unit admission (38.5% IV fluid hydration vs 19.9% nasogastric hydration; difference 18.6%, [5.1-32.1], P = .004); and use of ventilation support (27.7% IV fluid hydration vs 15.1% nasogastric hydration; difference 12.6 [0.3-23], P = .03). Fewer infants changed from nasogastric hydration to IV fluid hydration than from IV fluid hydration to nasogastric hydration (12.3% vs 47.7%; difference -35.4% [-49 to -22], P hydration can be used in the majority of young infants admitted with bronchiolitis. Nasogastric hydration and IV fluid hydration had similar rates of complications. Copyright © 2016 Elsevier Inc. All rights reserved.

Rapid hydrogen hydrate growth from non-stoichiometric tuning mixtures during liquid nitrogen quenching.

Science.gov (United States)

Grim, R Gary; Kerkar, Prasad B; Sloan, E Dendy; Koh, Carolyn A; Sum, Amadeu K

2012-06-21

In this study the rapid growth of sII H(2) hydrate within 20 min of post formation quenching towards liquid nitrogen (LN(2)) temperature is presented. Initially at 72 MPa and 258 K, hydrate samples would cool to the conditions of ~60 MPa and ~90 K after quenching. Although within the stability region for H(2) hydrate, new hydrate growth only occurred under LN(2) quenching of the samples when preformed hydrate "seeds" of THF + H(2) were in the presence of unconverted ice. The characterization of hydrate seeds and the post-quenched samples was performed with confocal Raman spectroscopy. These results suggest that quenching to LN(2) temperature, a common preservation technique for ex situ hydrate analysis, can lead to rapid unintended hydrate growth. Specifically, guest such as H(2) that may otherwise need sufficiently long induction periods to nucleate, may still experience rapid growth through an increased kinetic effect from a preformed hydrate template.

Can hydrate dissolution experiments predict the fate of a natural hydrate system?

Energy Technology Data Exchange (ETDEWEB)

Hester, K.C.; Peltzer, E.T.; Dunk, R.M.; Walz, P.M.; Brewer, P.G. [Monterey Bay Aquarium Research Inst., Moss Landing, CA (United States); Dendy Sloan, E. [Colorado School of Mines, Golden, CO (United States). Center for Hydrate Research

2008-07-01

Gas hydrates are naturally occurring compounds found in permafrost regions and in oceans. In the natural environment, sufficient temperature and pressure conditions for hydrate formation exist over a significant portion of the ocean. However, in addition to pressure and temperature, the chemical potential of the gas in the hydrate must be equal to the surrounding waters. If the concentration of the gas in surrounding water is under-saturated with respect to the gas in the hydrate, the hydrate will dissolve to drive the system towards chemical equilibrium. This paper presented a dissolution study of exposed hydrate from outcrops at Barkley Canyon, located off Vancouver Island, British Columbia. A previous field experiment on synthetic methane hydrate samples had demonstrated that mass transfer controlled dissolution in under-saturated seawater. However, seafloor hydrate outcrops have been shown to have significant longevity compared to expected dissolution rates based upon convective boundary layer diffusion calculations. An in-situ dissolution experiment was performed on two distinct natural hydrate fabrics in order to help resolve this apparent disconnect between the dissolution rates of synthetic and natural hydrate. The paper presented a map of Barkley Canyon and discussed the field measurements and methods for the study. Exposed outcrops of gas hydrates were cored using a specially constructed stainless steel coring device and a hydraulic ram was located inside the corer. Hydrate samples were cored directly using the a manipulator arm and then injected into a sampling cell. The hydrate was then added to an open mesh exposure container, which allowed for exposure to ambient benthic currents with minimal disturbance. As well, in order to observe the slow dissolution of the hydrate in seawater at Barkley Canyon, time-lapse photography was employed. Last, the paper presented the results of the hydrate fabric porosities and hydrate dissolution rates. It was

Low-δD hydration rinds in Yellowstone perlites record rapid syneruptive hydration during glacial and interglacial conditions

Science.gov (United States)

Bindeman, Ilya N.; Lowenstern, Jacob B.

2016-01-01

Hydration of silicic volcanic glass forms perlite, a dusky, porous form of altered glass characterized by abundant “onion-skin” fractures. The timing and temperature of perlite formation are enigmatic and could plausibly occur during eruption, during post-eruptive cooling, or much later at ambient temperatures. To learn more about the origin of natural perlite, and to fingerprint the hydration waters, we investigated perlitic glass from several synglacial and interglacial rhyolitic lavas and tuffs from the Yellowstone volcanic system. Perlitic cores are surrounded by a series of conchoidal cracks that separate 30- to 100-µm-thick slivers, likely formed in response to hydration-induced stress. H2O and D/H profiles confirm that most D/H exchange happens together with rapid H2O addition but some smoother D/H variations may suggest separate minor exchange by deuterium atom interdiffusion following hydration. The hydrated rinds (2–3 wt% H2O) transition rapidly (within 30 µm, or by 1 wt% H2O per 10 µm) to unhydrated glass cores. This is consistent with quenched “hydration fronts” where H2O diffusion coefficients are strongly dependent on H2O concentrations. The chemical, δ18O, and δD systematics of bulk glass records last equilibrium between ~110 and 60 °C without chemical exchange but with some δ18O exchange. Similarly, the δ18O of water extracted from glass by rapid heating suggests that water was added to the glass during cooling at higher rates of diffusion at 60–110 °C temperatures, compared with values expected from extrapolation of high-temperature (>400 °C) experimental data. The thick hydration rinds in perlites, measuring hundreds of microns, preserve the original D/H values of hydrating water as a recorder of paleoclimate conditions. Measured δD values in perlitic lavas are −150 to −191 or 20–40 ‰ lower than glass hydrated by modern Yellowstone waters. This suggests that Yellowstone perlites record the low-δD signature

Effect of overpressure on gas hydrate distribution

Energy Technology Data Exchange (ETDEWEB)

Bhatnagar, G.; Chapman, W.G.; Hirasaki, G.J. [Rice Univ., Houston, TX (United States). Dept. of Chemical and Biomolecular Engineering; Dickens, G.R.; Dugan, B. [Rice Univ., Houston, TX (United States). Dept. of Earth Sciences

2008-07-01

Natural gas hydrate systems can be characterized by high sedimentation rates and/or low permeability sediments, which can lead to pore pressure higher than hydrostatic. This paper discussed a study that examined this effect of overpressure on gas hydrate and free gas distribution in marine sediments. A one-dimensional numerical model that coupled sedimentation, fluid flow, and gas hydrate formation was utilized. In order to quantify the relative importance of sedimentation rates and low permeability sediments, a dimensionless sedimentation-compaction group (scN) was defined, that compared the absolute permeability of the sediments to the sedimentation rate. Higher values of scN mean higher permeability or low sedimentation rate which generally yield hydrostatic pore pressure while lower values of scN normally create pore pressure greater than hydrostatic. The paper discussed non-hydrostatic consolidation in gas hydrate systems, including mass balances; constitutive relationships; normalized variables; and dimensionless groups. A numerical solution to the problem was presented. It was concluded that simulation results demonstrated that decreasing scN not only increased pore pressure above hydrostatic values, but also lowered the lithostatic stress gradient and gas hydrate saturation. This occurred because overpressure resulted in lower effective stress, causing higher porosity and lower bulk density of the sediment. 16 refs., 5 figs., 1 appendix.

Preparation, characterization, and thermal properties of the microencapsulation of a hydrated salt as phase change energy storage materials

International Nuclear Information System (INIS)

Huang, Jin; Wang, Tingyu; Zhu, Panpan; Xiao, Junbin

2013-01-01

Highlights: ► Phase change point and fusion heat of samples are about 51 °Cand 150 J/g respectively. ► DSC results indicated the core material is not Na 2 HPO 4 ·12H 2 O but Na 2 HPO 4 ·7H 2 O. ► Encapsulation takes a significant role in reducing subcooling degree. - Abstract: Microcapsules loaded by disodium hydrogen phosphate heptahydrate (Na 2 HPO 4 ·7H 2 O) were prepared by means of the suspension copolymerization-solvent volatile method, with modified polymethylmethacrylate (PMMA) as coating polymer under the conditions of various organic solvents. The formation of the microencapsulated phase change materials (MEPCMs)-PMMA/Na 2 HPO 4 ·7H 2 O was investigated and analyzed. The morphology of the resultant materials was characterized by using scanning electron microscope (SEM) and phase contrast microscope. Its final composition was confirmed by the Fourier transformation infrared (FT-IR). Thermo gravimetric analyzer (TGA) and differential scanning calorimetry (DSC) were adopted to reveal its thermal stability and thermal properties. Results indicated that the materials owned improved subcooling degree and good thermal properties, enabling the materials to be one promising phase change materials for thermal energy storage

Preparation, characterization, and thermal properties of the microencapsulation of a hydrated salt as phase change energy storage materials

Energy Technology Data Exchange (ETDEWEB)

Huang, Jin, E-mail: huangjiner@126.com [School of Materials and Energy, Guangdong University of Technology, 510006 Guangzhou (China); Wang, Tingyu; Zhu, Panpan; Xiao, Junbin [School of Materials and Energy, Guangdong University of Technology, 510006 Guangzhou (China)

2013-04-10

Highlights: ► Phase change point and fusion heat of samples are about 51 °Cand 150 J/g respectively. ► DSC results indicated the core material is not Na{sub 2}HPO{sub 4}·12H{sub 2}O but Na{sub 2}HPO{sub 4}·7H{sub 2}O. ► Encapsulation takes a significant role in reducing subcooling degree. - Abstract: Microcapsules loaded by disodium hydrogen phosphate heptahydrate (Na{sub 2}HPO{sub 4}·7H{sub 2}O) were prepared by means of the suspension copolymerization-solvent volatile method, with modified polymethylmethacrylate (PMMA) as coating polymer under the conditions of various organic solvents. The formation of the microencapsulated phase change materials (MEPCMs)-PMMA/Na{sub 2}HPO{sub 4}·7H{sub 2}O was investigated and analyzed. The morphology of the resultant materials was characterized by using scanning electron microscope (SEM) and phase contrast microscope. Its final composition was confirmed by the Fourier transformation infrared (FT-IR). Thermo gravimetric analyzer (TGA) and differential scanning calorimetry (DSC) were adopted to reveal its thermal stability and thermal properties. Results indicated that the materials owned improved subcooling degree and good thermal properties, enabling the materials to be one promising phase change materials for thermal energy storage.

Ultrasonic sound speed of hydrating calcium sulphate hemihydrate; part 1, the calculation of sound speed of slurries and hardened porous material

NARCIS (Netherlands)

de Korte, A.C.J.; Brouwers, Jos

2011-01-01

This article focuses on the computation of the sound velocity through slurries and hardened products. The purpose is to use the sound velocity to quantify the composition of the fresh slurry as well as the hardening and hardened - porous - material. Therefore the volumetric models for hydration of

Gas hydrate nucleation

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-31

The overall aim of the project was to gain more knowledge about the kinetics of gas hydrate formation especially the early growth phase. Knowledge of kinetics of gas hydrate formation is important and measurements of gas hydrate particle size and concentration can contribute to improve this knowledge. An experimental setup for carrying out experimental studies of the nucleation and growth of gas hydrates has been constructed and tested. Multi wavelength extinction (MWE) was the experimental technique selected for obtaining particle diameter and concentration. The principle behind MWE is described as well as turbidity spectrum analysis that in an initial stage of the project was considered as an alternative experimental technique. Details of the experimental setup and its operation are outlined. The measuring cell consists of a 1 litre horizontal tube sustaining pressures up to 200 bar. Laser light for particle size determination can be applied through sapphire windows. A description of the various auxiliary equipment and of another gas hydrate cell used in the study are given. A computer program for simulation and analysis of gas hydrate experiments is based on the gas hydrate kinetics model proposed by Skovborg and Rasmussen (1993). Initial measurements showed that knowledge of the refractive index of gas hydrates was important in order to use MWE. An experimental determination of the refractive index of methane and natural gas hydrate is described. The test experiments performed with MWE on collectives of gas hydrate particles and experiments with ethane, methane and natural gas hydrate are discussed. Gas hydrate particles initially seem to grow mainly in size and at latter stages in number. (EG) EFP-94; 41 refs.

Gas hydrate nucleation

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-31

The overall aim of the project was to gain more knowledge about the kinetics of gas hydrate formation especially the early growth phase. Knowledge of kinetics of gas hydrate formation is important and measurements of gas hydrate particle size and concentration can contribute to improve this knowledge. An experimental setup for carrying out experimental studies of the nucleation and growth of gas hydrates has been constructed and tested. Multi wavelength extinction (MWE) was the experimental technique selected for obtaining particle diameter and concentration. The principle behind MWE is described as well as turbidity spectrum analysis that in an initial stage of the project was considered as an alternative experimental technique. Details of the experimental setup and its operation are outlined. The measuring cell consists of a 1 litre horizontal tube sustaining pressures up to 200 bar. Laser light for particle size determination can be applied through sapphire windows. A description of the various auxiliary equipment and of another gas hydrate cell used in the study are given. A computer program for simulation and analysis of gas hydrate experiments is based on the gas hydrate kinetics model proposed by Skovborg and Rasmussen (1993). Initial measurements showed that knowledge of the refractive index of gas hydrates was important in order to use MWE. An experimental determination of the refractive index of methane and natural gas hydrate is described. The test experiments performed with MWE on collectives of gas hydrate particles and experiments with ethane, methane and natural gas hydrate are discussed. Gas hydrate particles initially seem to grow mainly in size and at latter stages in number. (EG) EFP-94; 41 refs.

Gas hydrates

Digital Repository Service at National Institute of Oceanography (India)

Ramprasad, T.

, not all of them are white like snow. Some hydrates from the deep Gulf of Mexico are richly colored in shades of yellow, orange, or even red. The ice-like masses are beautiful, and contrast with the dull gray of deep sea muds. Hydrates from the Blake... volcanoes and associated gas hydrates: Marine Geology, v. 167, p. 29-42. Milkov, A.V. and R. Sassen, 2001a, Estimate of gas hydrate resource, northwestern Gulf of Mexico continental slope: Marine Geology, v. 179, pp. 71-83. Milkov, A.V., Sassen, R...

Micromechanisms of fatigue crack growth in polycarbonate polyurethane: Time dependent and hydration effects.

Science.gov (United States)

Ford, Audrey C; Gramling, Hannah; Li, Samuel C; Sov, Jessica V; Srinivasan, Amrita; Pruitt, Lisa A

2018-03-01

Polycarbonate polyurethane has cartilage-like, hygroscopic, and elastomeric properties that make it an attractive material for orthopedic joint replacement application. However, little data exists on the cyclic loading and fracture behavior of polycarbonate polyurethane. This study investigates the mechanisms of fatigue crack growth in polycarbonate polyurethane with respect to time dependent effects and conditioning. We studied two commercially available polycarbonate polyurethanes, Bionate® 75D and 80A. Tension testing was performed on specimens at variable time points after being removed from hydration and variable strain rates. Fatigue crack propagation characterized three aspects of loading. Study 1 investigated the impact of continuous loading (24h/day) versus intermittent loading (8-10h/day) allowing for relaxation overnight. Study 2 evaluated the effect of frequency and study 3 examined the impact of hydration on the fatigue crack propagation in polycarbonate polyurethane. Samples loaded intermittently failed instantaneously and prematurely upon reloading while samples loaded continuously sustained longer stable cracks. Crack growth for samples tested at 2 and 5Hz was largely planar with little crack deflection. However, samples tested at 10Hz showed high degrees of crack tip deflection and multiple crack fronts. Crack growth in hydrated samples proceeded with much greater ductile crack mouth opening displacement than dry samples. An understanding of the failure mechanisms of this polymer is important to assess the long-term structural integrity of this material for use in load-bearing orthopedic implant applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

BACCHUS 2: an in situ backfill hydration experiment for model validation

International Nuclear Information System (INIS)

Volckaert, G.; Bernier, F.; Alonso, E.; Gens, A.

1995-01-01

The BACCHUS 2 experiment is an in situ backfill hydration test performed in the HADES underground research facility situated in the plastic Boom clay layer at 220 m depth. The experiment aims at the optimization and demonstration of an installation procedure for a clay based backfill material. The instrumentation has been optimized in such a way that the results of the experiments can be used for the validation of hydro-mechanical codes such a NOSAT developed at the University of Catalunya Spain (UPC). The experimental set-up consists in a bottom flange and a central filter around which the backfill material was applied. The backfill material consist of a mixture of high density clay pellets and clay powder. The experimental set-up and its instrumentation are described in detail. The results of the hydro-mechanical characterization of the backfill material is summarized. (authors). 8 refs., 16 figs., 1 tab

Shifting Focus: From Hydration for Performance to Hydration for Health.

Science.gov (United States)

Perrier, Erica T

2017-01-01

Over the past 10 years, literature on hydration biomarkers has evolved considerably - from (de)hydration assessment towards a more global definition of biomarkers of hydration in daily life. This shift in thinking about hydration markers was largely driven by investigating the differences that existed between otherwise healthy individuals whose habitual, ad-libitum drinking habits differ, and by identifying physiological changes in low-volume drinkers who subsequently increase their water intake. Aside from obvious differences in urinary volume and concentration, a growing body of evidence is emerging that links differences in fluid intake with small, but biologically significant, differences in vasopressin (copeptin), glomerular filtration rate, and markers of metabolic dysfunction or disease. Taken together, these pieces of the puzzle begin to form a picture of how much water intake should be considered adequate for health, and represent a shifting focus from hydration for performance, toward hydration for health outcomes. This narrative review outlines the key areas of research in which the global hydration process - including water intake, urinary hydration markers, and vasopressin - has been associated with health outcomes, focusing on kidney and metabolic endpoints. It will also provide a commentary on how various hydration biomarkers may be used in hydration for health assessment. Finally, if adequate water intake can play a role in maintaining health, how might we tell if we are drinking enough? Urine output is easily measured, and can take into account differences in daily physical activity, climate, dietary solute load, and other factors that influence daily water needs. Today, targets have been proposed for urine osmolality, specific gravity, and color that may be used by researchers, clinicians, and individuals as simple indicators of optimal hydration. However, there remain a large number of incomplete or unanswered research questions regarding the

Steam hydration-reactivation of FBC ashes for enhanced in situ desulphurization

Energy Technology Data Exchange (ETDEWEB)

Fabio Montagnaro; Marianna Nobili; Antonio Telesca; Gian Lorenz Valenti; Edward J. Anthony; Piero Salatino [Universita degli Studi di Napoli Federico II, Napoli (Italy). Dipartimento di Chimica

2009-06-15

Bed and fly ashes originating from industrial-scale fluidized bed combustors (FBCs) were steam hydrated to produce sorbents suitable for further in situ desulphurization. Samples of the hydrated ash were characterized by X-ray diffraction analysis, scanning electron microscopy and porosimetry. Bed ashes were hydrated in a pressure bomb for 30 and 60 min at 200{sup o}C and 250{sup o}C. Fly ash was hydrated in an electrically heated tubular reactor for 10 and 60 min at 200{sup o}C and 300{sup o}C. The results were interpreted by considering the hydration process and the related development of accessible porosity suitable for resulphation. The performance of the reactivated bed ash as sulphur sorbent improved with a decrease of both the hydration temperature and time. For reactivated fly ash, more favourable porosimetric features were observed at longer treatment times and lower hydration temperatures. Finally, it was shown that an ashing treatment (at 850{sup o}C for 20 min) promoted a speeding up of the hydration process and an increase in the accessible porosity. 36 refs., 6 figs., 2 tabs.

Challenges, uncertainties and issues facing gas production from gas hydrate deposits

Energy Technology Data Exchange (ETDEWEB)

Moridis, G.J.; Collett, T.S.; Pooladi-Darvish, M.; Hancock, S.; Santamarina, C.; Boswell, R.; Kneafsey, T.; Rutqvist, J.; Kowalsky, M.; Reagan, M.T.; Sloan, E.D.; Sum, A.K.; Koh, C.

2010-11-01

The current paper complements the Moridis et al. (2009) review of the status of the effort toward commercial gas production from hydrates. We aim to describe the concept of the gas hydrate petroleum system, to discuss advances, requirement and suggested practices in gas hydrate (GH) prospecting and GH deposit characterization, and to review the associated technical, economic and environmental challenges and uncertainties, including: the accurate assessment of producible fractions of the GH resource, the development of methodologies for identifying suitable production targets, the sampling of hydrate-bearing sediments and sample analysis, the analysis and interpretation of geophysical surveys of GH reservoirs, well testing methods and interpretation of the results, geomechanical and reservoir/well stability concerns, well design, operation and installation, field operations and extending production beyond sand-dominated GH reservoirs, monitoring production and geomechanical stability, laboratory investigations, fundamental knowledge of hydrate behavior, the economics of commercial gas production from hydrates, and the associated environmental concerns.

Impacts of Hydrate Distribution on the Hydro-Thermo-Mechanical Properties of Hydrate-Bearing Sediments

Science.gov (United States)

Dai, S.; Seol, Y.

2015-12-01

In general, hydrate makes the sediments hydraulically less conductive, thermally more conductive, and mechanically stronger; yet the dependency of these physical properties on hydrate saturation varies with hydrate distribution and morphology. Hydrate distribution in sediments may cause the bulk physical properties of their host sediments varying several orders of magnitude even with the same amount of hydrate. In natural sediments, hydrate morphology is inherently governed by the burial depth and the grain size of the host sediments. Compare with patchy hydrate, uniformly distributed hydrate is more destructive to fluid flow, yet leads to higher gas and water permeability during hydrate dissociation due to the easiness of forming percolation paths. Water and hydrate have similar thermal conductivity values; the bulk thermal conductivity of hydrate-bearing sediments depends critically on gas-phase saturation. 60% of gas saturation may result in evident thermal conductivity drop and hinder further gas production. Sediments with patchy hydrate yield lower stiffness than that with cementing hydrate but higher stiffness than that with pore filling and loading bearing hydrate. Besides hydrate distribution, the stress state and loading history also play an important role in the mechanical behavior of hydrate-bearing sediments.

The analysis of magnesium oxide hydration in three-phase reaction system

Energy Technology Data Exchange (ETDEWEB)

Tang, Xiaojia; Guo, Lin; Chen, Chen; Liu, Quan; Li, Tie; Zhu, Yimin, E-mail: ntp@dlmu.edu.cn

2014-05-01

In order to investigate the magnesium oxide hydration process in gas–liquid–solid (three-phase) reaction system, magnesium hydroxide was prepared by magnesium oxide hydration in liquid–solid (two-phase) and three-phase reaction systems. A semi-empirical model and the classical shrinking core model were used to fit the experimental data. The fitting result shows that both models describe well the hydration process of three-phase system, while only the semi-empirical model right for the hydration process of two-phase system. The characterization of the hydration product using X-Ray diffraction (XRD) and scanning electron microscope (SEM) was performed. The XRD and SEM show hydration process in the two-phase system follows common dissolution/precipitation mechanism. While in the three-phase system, the hydration process undergo MgO dissolution, Mg(OH){sub 2} precipitation, Mg(OH){sub 2} peeling off from MgO particle and leaving behind fresh MgO surface. - Graphical abstract: There was existence of a peeling-off process in the gas–liquid–solid (three-phase) MgO hydration system. - Highlights: • Magnesium oxide hydration in gas–liquid–solid system was investigated. • The experimental data in three-phase system could be fitted well by two models. • The morphology analysis suggested that there was existence of a peel-off process.

Comparison of setting time and temperature hydration in mortar with substituent ceramic

International Nuclear Information System (INIS)

Rodrigues, R.A.; Alves, L.S.; Evangelista, A.C.J.; Almeida, V.C.

2011-01-01

The workability of mortar is determined mainly by the kinetics of hydration of the hydraulic binder, the process of gelation / hydration of this material in aqueous solutions is significantly influenced by the presence of additives. As a result, this work aims at studying changes in setting time and temperature of hydration of mortars with 10, 15 and 30% of Portland cement replaced by residues of porcelain and ceramic bricks. The influence of these residues in the cement hydration process was studied by testing takes time, temperature, hydration and X-ray diffraction. The results indicate that the mortar setting time not changed significantly since the temperature of hydration has a minor variation on what is preferred because it reduces the microcracks created in mortar during drying.(author)

Surface Assisted Formation of methane Hydrates on Ice and Na Montmorillonite Clay

Energy Technology Data Exchange (ETDEWEB)

Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Teich-McGoldrick, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cygan, Randall Timothy [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Meserole, Stephen P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rodriguez, Mark A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-07-01

Methane hydrates are extremely important naturally-occurring crystalline materials that impact climate change, energy resources, geological hazards, and other major environmental issues. Whereas significant experimental effort has been completed to understanding the bulk thermodynamics of methane hydrate assemblies, little is understood on heterogeneous nucleation and growth of methane hydrates in clay-rich environments. Controlled synthesis experiments were completed at 265-285 K and 6.89 MPa to examine the impact of montmorillonite surfaces in clay-ice mixtures to nucleate and form methane hydrate. The results suggest that the hydrophilic and methane adsorbing properties of Namontmorillonite reduce the nucleation period of methane hydrate formation in pure ice systems.

A pressure core ultrasonic test system for on-board analysis of gas hydrate-bearing sediments under in situ pressures.

Science.gov (United States)

Yang, Lei; Zhou, Weihua; Xue, Kaihua; Wei, Rupeng; Ling, Zheng

2018-05-01

The enormous potential as an alternative energy resource has made natural gas hydrates a material of intense research interest. Their exploration and sample characterization require a quick and effective analysis of the hydrate-bearing cores recovered under in situ pressures. Here a novel Pressure Core Ultrasonic Test System (PCUTS) for on-board analysis of sediment cores containing gas hydrates at in situ pressures is presented. The PCUTS is designed to be compatible with an on-board pressure core transfer device and a long gravity-piston pressure-retained corer. It provides several advantages over laboratory core analysis including quick and non-destructive detection, in situ and successive acoustic property acquisition, and remission of sample storage and transportation. The design of the unique assembly units to ensure the in situ detection is demonstrated, involving the U-type protecting jackets, transducer precession device, and pressure stabilization system. The in situ P-wave velocity measurements make the detection of gas hydrate existence in the sediments possible on-board. Performance tests have verified the feasibility and sensitivity of the ultrasonic test unit, showing the dependence of P-wave velocity on gas hydrate saturation. The PCUTS has been successfully applied for analysis of natural samples containing gas hydrates recovered from the South China Sea. It is indicated that on-board P-wave measurements could provide a quick and effective understanding of the hydrate occurrence in natural samples, which can assist further resource exploration, assessment, and subsequent detailed core analysis.

A pressure core ultrasonic test system for on-board analysis of gas hydrate-bearing sediments under in situ pressures

Science.gov (United States)

Yang, Lei; Zhou, Weihua; Xue, Kaihua; Wei, Rupeng; Ling, Zheng

2018-05-01

The enormous potential as an alternative energy resource has made natural gas hydrates a material of intense research interest. Their exploration and sample characterization require a quick and effective analysis of the hydrate-bearing cores recovered under in situ pressures. Here a novel Pressure Core Ultrasonic Test System (PCUTS) for on-board analysis of sediment cores containing gas hydrates at in situ pressures is presented. The PCUTS is designed to be compatible with an on-board pressure core transfer device and a long gravity-piston pressure-retained corer. It provides several advantages over laboratory core analysis including quick and non-destructive detection, in situ and successive acoustic property acquisition, and remission of sample storage and transportation. The design of the unique assembly units to ensure the in situ detection is demonstrated, involving the U-type protecting jackets, transducer precession device, and pressure stabilization system. The in situ P-wave velocity measurements make the detection of gas hydrate existence in the sediments possible on-board. Performance tests have verified the feasibility and sensitivity of the ultrasonic test unit, showing the dependence of P-wave velocity on gas hydrate saturation. The PCUTS has been successfully applied for analysis of natural samples containing gas hydrates recovered from the South China Sea. It is indicated that on-board P-wave measurements could provide a quick and effective understanding of the hydrate occurrence in natural samples, which can assist further resource exploration, assessment, and subsequent detailed core analysis.

Experimental determination of methane hydrate formation in the presence of ammonia

Energy Technology Data Exchange (ETDEWEB)

Dong, T.B.; Wang, L.Y.; Liu, A.X.; Guo, X.Q.; Chen, G.J.; Ma, Q.L.; Li, G.W. [China Univ. of Petroleum, Beijng (China). State Key Laboratory of Heavy Oil Processing

2008-07-01

Gas hydrates are non-stoichiometric inclusion compounds that are created by a lattice of water molecules. The host molecule has a strong hydrogen bond and encages low molecular weight gases or volatile liquids. The guest molecules favor hydrate formation. Historically, gas hydrates have been thought to be problematic during natural gas transportation because the formed solid hydrate can block pipelines and cause tubing and casing collapse. However, the discovery of huge deposits of gas hydrates in deep-sea sediments and in permafrost has renewed interest in gas hydrates as a new energy resource. This paper discussed a study that is a part of an ongoing experimental and computational program dealing with the thermodynamics of gas hydrate formation in ammonia-water systems. The purpose of the study was to develop a new method to separate and recycle the vent gas of ammonia synthesis by forming or dissociating hydrate. The hydrate-forming conditions of methane in ammonia and water system were studied and reported in this paper with reference to the experimental apparatus and procedure. The materials and preparation of samples were also explained. The experimental results showed that the ammonia had an inhibitive effect on the hydrate formation. 26 refs., 2 tabs., 3 figs.

Purpose of the Materials Characterization Center

International Nuclear Information System (INIS)

Mendel, J.E.

1984-09-01

The Materials Characterization Center (MCC) at the Pacific Northwest Laboratory is the experimental arm of the Materials Characterization Organization (MCO), which was established by the US Department of Energy (DOE) in FY 1980 to ensure high quality characterization and qualification of waste package materials essential to the reliable performance of DOE nuclear waste management programs. MCC is responsible for publishing key test methods and data in the Nuclear Waste Materials Handbook (DOE/TIC-11400). It sponsors a continuing series of workshops that address materials characterization test method issues. It supplies well-characterized reference and testing materials for use by the DOE nuclear waste management programs. It develops generic test methods and supports the repository waste package projects in developing selected site-specific test methods and performing confirmatory testing of these methods. When these test methods are approved by the MRB they constitute the formal tests to be used by laboratories to test and qualify materials, evaluate waste package components, and assure compliance with standards and/or specifications for the final product

The impact of permafrost-associated microorganisms on hydrate formation kinetics

Science.gov (United States)

Luzi-Helbing, Manja; Liebner, Susanne; Spangenberg, Erik; Wagner, Dirk; Schicks, Judith M.

2016-04-01

The relationship between gas hydrates, microorganisms and the surrounding sediment is extremely complex: On the one hand, microorganisms producing methane provide the prerequisite for gas hydrate formation. As it is known most of the gas incorporated into natural gas hydrates originates from biogenic sources. On the other hand, as a result of microbial activity gas hydrates are surrounded by a great variety of organic compounds which are not incorporated into the hydrate structure but may influence the formation or degradation process. For gas hydrate samples from marine environments such as the Gulf of Mexico a direct association between microbes and gas hydrates was shown by Lanoil et al. 2001. It is further assumed that microorganisms living within the gas hydrate stability zone produce biosurfactants which were found to enhance the hydrate formation process significantly and act as nucleation centres (Roger et al. 2007). Another source of organic compounds is sediment organic matter (SOM) originating from plant material or animal remains which may also enhance hydrate growth. So far, the studies regarding this relationship were focused on a marine environment. The scope of this work is to extend the investigations to microbes originating from permafrost areas. To understand the influence of microbial activity in a permafrost environment on the methane hydrate formation process and the stability conditions of the resulting hydrate phase we will perform laboratory studies. Thereby, we mimic gas hydrate formation in the presence and absence of methanogenic archaea (e.g. Methanosarcina soligelidi) and other psychrophilic bacteria isolated from permafrost environments of the Arctic and Antarctic to investigate their impact on hydrate induction time and formation rates. Our results may contribute to understand and predict the occurrences and behaviour of potential gas hydrates within or adjacent to the permafrost. Lanoil BD, Sassen R, La Duc MT, Sweet ST, Nealson KH

Nuclear Well Log Properties of Natural Gas Hydrate Reservoirs

Science.gov (United States)

Burchwell, A.; Cook, A.

2015-12-01

Characterizing gas hydrate in a reservoir typically involves a full suite of geophysical well logs. The most common method involves using resistivity measurements to quantify the decrease in electrically conductive water when replaced with gas hydrate. Compressional velocity measurements are also used because the gas hydrate significantly strengthens the moduli of the sediment. At many gas hydrate sites, nuclear well logs, which include the photoelectric effect, formation sigma, carbon/oxygen ratio and neutron porosity, are also collected but often not used. In fact, the nuclear response of a gas hydrate reservoir is not known. In this research we will focus on the nuclear log response in gas hydrate reservoirs at the Mallik Field at the Mackenzie Delta, Northwest Territories, Canada, and the Gas Hydrate Joint Industry Project Leg 2 sites in the northern Gulf of Mexico. Nuclear logs may add increased robustness to the investigation into the properties of gas hydrates and some types of logs may offer an opportunity to distinguish between gas hydrate and permafrost. For example, a true formation sigma log measures the thermal neutron capture cross section of a formation and pore constituents; it is especially sensitive to hydrogen and chlorine in the pore space. Chlorine has a high absorption potential, and is used to determine the amount of saline water within pore spaces. Gas hydrate offers a difference in elemental composition compared to water-saturated intervals. Thus, in permafrost areas, the carbon/oxygen ratio may vary between gas hydrate and permafrost, due to the increase of carbon in gas hydrate accumulations. At the Mallik site, we observe a hydrate-bearing sand (1085-1107 m) above a water-bearing sand (1107-1140 m), which was confirmed through core samples and mud gas analysis. We observe a decrease in the photoelectric absorption of ~0.5 barnes/e-, as well as an increase in the formation sigma readings of ~5 capture units in the water-bearing sand as

Materials Characterization Facility

Data.gov (United States)

Federal Laboratory Consortium — The Materials Characterization Facility enables detailed measurements of the properties of ceramics, polymers, glasses, and composites. It features instrumentation...

Preparation and Supercooling Modification of Salt Hydrate Phase Change Materials Based on CaCl₂·2H₂O/CaCl₂.

Science.gov (United States)

Xu, Xiaoxiao; Dong, Zhijun; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi

2017-06-23

Salt hydrates have issues of supercooling when they are utilized as phase change materials (PCMs). In this research, a new method was adopted to prepare a salt hydrate PCM (based on a mixture of calcium chloride dihydrate and calcium chloride anhydrous) as a novel PCM system to reduce the supercooling phenomenon existing in CaCl₂·6H₂O. Six samples with different compositions of CaCl₂ were prepared. The relationship between the performance and the proportion of calcium chloride dihydrate (CaCl₂·2H₂O) and calcium chloride anhydrous (CaCl₂) was also investigated. The supercooling degree of the final PCM reduced with the increase in volume of CaCl₂·2H₂O during its preparation. The PCM obtained with 66.21 wt % CaCl₂·2H₂O reduced the supercooling degree by about 96.8%. All six samples, whose ratio of CaCl₂·2H₂O to (CaCl₂ plus CaCl₂·2H₂O) was 0%, 34.03%, 53.82%, 76.56%, 90.74%, and 100% respectively, showed relatively higher enthalpy (greater than 155.29 J/g), and have the possibility to be applied in buildings for thermal energy storage purposes. Hence, CaCl₂·2H₂O plays an important role in reducing supercooling and it can be helpful in adjusting the solidification enthalpy. Thereafter, the influence of adding different percentages of Nano-SiO₂ (0.1 wt %, 0.3 wt %, 0.5 wt %) in reducing the supercooling degree of some PCM samples was investigated. The test results showed that the supercooling of the salt hydrate PCM in Samples 6 and 5 reduced to 0.2 °C and 0.4 °C respectively. Finally, the effect of the different cooling conditions, including frozen storage (-20 °C) and cold storage (5 °C), that were used to prepare the salt hydrate PCM was considered. It was found that both cooling conditions are effective in reducing the supercooling degree of the salt hydrate PCM. With the synergistic action of the two materials, the performance and properties of the newly developed PCM systems were better especially in terms of reducing

Limitation of biocompatibility of hydrated nanocrystalline hydroxyapatite

Science.gov (United States)

Minaychev, V. V.; Teleshev, A. T.; Gorshenev, V. N.; Yakovleva, M. A.; Fomichev, V. A.; Pankratov, A. S.; Menshikh, K. A.; Fadeev, R. S.; Fadeeva, I. S.; Senotov, A. S.; Kobyakova, M. I.; Yurasova, Yu B.; Akatov, V. S.

2018-04-01

Nanostructured hydroxyapatite (HA) in the form of hydrated paste is considered to be a promising material for a minor-invasive surgical curing of bone tissue injure. However questions about adhesion of cells on this material and its biocompatibility still remain. In this study biocompatibility of paste-formed nanosized HA (nano-HA) by in vitro methods is investigated. Nano-HA (particles sized about 20 nm) was synthesized under conditions of mechano-acoustic activation of an aqueous reaction mixture of ammonium hydrophosphate and calcium nitrate. It was ascertained that nanocrystalline paste was not cytotoxic although limitation of adhesion, spreading and growth of the cells on its surface was revealed. The results obtained point on the need of modification of hydrated nano-HA in the aims of increasing its biocompatibility and osteoplastic potential.

Thermal Stability and Proton Conductivity of Rare Earth Orthophosphate Hydrates

DEFF Research Database (Denmark)

Anfimova, Tatiana; Li, Qingfeng; Jensen, Jens Oluf

2014-01-01

as the rhabdophane structure is preserved. The bound hydrate water is accommodated in the rhabdophane structure and is stable at temperatures of up to 650 oC. The thermal stability of the hydrate water and the phosphate structure are of significance for the proton conductivity. The LaPO4·0.6H2O and NdPO4•0.5H2O......Hydrated orthophosphate powders of three rare earth metals, lanthanum, neodymium and gadolinium, were prepared and studied as potential proton conducting materials for intermediate temperature electrochemical applications. The phosphates undergo a transformation from the rhabdophane structure...... to the monazite structure upon dehydration. The thermal stability of the hydrate is studied and found to contain water of two types, physically adsorbed and structurally bound hydrate water. The adsorbed water is correlated to the specific surface area and can be reversibly recovered when dehydrated as long...

Formation and dissociation of CO{sub 2} and CO{sub 2}-THF hydrates compared to CH{sub 4} and CH{sub 4}-THF hydrates

Energy Technology Data Exchange (ETDEWEB)

Giavarini, C.; Maccioni, F.; Broggi, A. [Roma Univ. La Sapienza, Roma (Italy). Dept. of Chemical Engineering; Politi, M. [ENEL-RICERCHE, Brindisi (Italy)

2008-07-01

Carbon sequestration involves the removal of greenhouse gases from industrial or utility plant streams and their long term storage so that they cannot interact with the climate system. Different methods for selective carbon dioxide (CO{sub 2}) removal are in commercial use and are based on, gas absorption, membrane process, and cryogenic fractionation. In addition, disposal of captured CO{sub 2} in the ocean and in geological reservoirs has been proposed by researchers. Another challenge is to take advantage of the properties of CO{sub 2} hydrates for carbon sequestration since it could have a number of uses such as chemical production. As such, it is important to understand the hydrate decomposition kinetics during storage, transportation, and disposal. This paper presented a project that involved the separation of carbon dioxide from the flue gases of powers plants, in the form of hydrate. The project also involved the storage, use, and disposal of the hydrate. The purpose of the study was to evaluate the decomposition kinetics of CO{sub 2} hydrate containing different quantities of ice, at low pressures and temperatures between -3 and 0 degrees Celsius. In addition, in order to evaluate the tetrahydrofuran (THF) stabilization effect, the study examined the influence of THF on the formation and decomposition kinetics of mixed THF-methane (CH{sub 4}) and THF-CO{sub 2} hydrates. Preservation tests were conducted to determine the best pressure and temperature conditions for the mixed-hydrates conservation, with reference to the simple hydrates. The paper described the apparatus for the formation and dissociation tests which consisted of a jacketed stainless steel reactor, equipped with stirrer. The paper also described the hydrate formation procedure as well as hydrate characterization. Last, the paper discussed the hydrate dissociation tests that were conducted immediately after hydrate formation in the reactor. It was concluded that the hydrophilic and hydrophobic

Materials Characterization Center program plan

International Nuclear Information System (INIS)

Nelson, R.D.; Ross, W.A.; Hill, O.F.; Mendel, J.E.; Merz, M.D.; Turcotte, R.P.

1980-03-01

The Materials Characterization Center (MCC) has been established at Pacific Northwest Laboratory as part of the Materials Characterization Organization for providing an authoritative, referenceable basis for establishing nuclear waste material properties and test methods. The MCC will provide a data base that will include information on the components of the waste emplacement package - the spent fuel or processed waste form and the engineered barriers - and their interaction with each other and as affected by the environment. The MCC will plan materials testing, develop and document procedures, collect and analyze existing materials data, and conduct tests as necessary

Characterization of Nanophase Materials

Science.gov (United States)

Wang, Zhong Lin

2000-01-01

Engineering of nanophase materials and devices is of vital interest in electronics, semiconductors and optics, catalysis, ceramics and magnetism. Research associated with nanoparticles has widely spread and diffused into every field of scientific research, forming a trend of nanocrystal engineered materials. The unique properties of nanophase materials are entirely determined by their atomic scale structures, particularly the structures of interfaces and surfaces. Development of nanotechnology involves several steps, of which characterization of nanoparticles is indespensable to understand the behavior and properties of nanoparticles, aiming at implementing nanotechnolgy, controlling their behavior and designing new nanomaterials systems with super performance. The book will focus on structural and property characterization of nanocrystals and their assemblies, with an emphasis on basic physical approach, detailed techniques, data interpretation and applications. Intended readers of this comprehensive reference work are advanced graduate students and researchers in the field, who are specialized in materials chemistry, materials physics and materials science.

Dissociation behavior of methane gas hydrate in porous media

Energy Technology Data Exchange (ETDEWEB)

Qiang, C.; Yu-gang, Y.; Chang-ling, L. [Ministry of Land and Resources, Quindao (China). Qingdao Inst. of Marine Geology; Qing-guo, M. [Qingdao Univ. College of Chemical Engineering and Environment, Shandong, Qingdao (China)

2008-07-01

Gas hydrates are ice-like compounds that form by natural gas and water and are considered to be a new energy resource. In order to make good use of this resource, it is important to know the hydrate dissociation process. This paper discussed an investigation of methane hydrate dissociation through a simulation experiment. The paper discussed the gas hydrates dissociation experiment including the apparatus and experiment equipment, including methane gas supply; reaction cell; temperature controller; pressure maintainer; and gas flow meter. The paper also presented the method and material including iso-volumetric dissociation and normal pressure dissociation. Last, results and discussion of the results were presented. A comparison of five different particle sizes did not reveal any obvious effects that were related to the porous media, mostly likely because the particle size was too large. 15 refs., 2 tabs., 4 figs.

Impact of pore-water freshening on clays and the compressibility of hydrate-bearing reservoirs during production

Energy Technology Data Exchange (ETDEWEB)

Jang, Junbong [U.S. Geological Survey, Woods Hole, MA; Cao, Shuang [Louisiana State University, Baton Rouge, LA; Waite, William [U.S. Geological Survey, Woods Hole, MA; Jung, Jongwon [Chungbuk National University, Cheongju-si, Chungbuk, South Korea

2017-06-25

Gas production efficiency from natural hydrate-bearing sediments depends in part on geotechnical properties of fine-grained materials, which are ubiquitous even in sandy hydrate-bearing sediments. The responses of fine-grained material to pore fluid chemistry changes due to freshening during hydrate dissociation could alter critical sediment characteristics during gas production activities. We investigate the electrical sensitivity of fine grains to pore fluid freshening and the implications of freshening on sediment compression and recompression parameters.

Material for desulphurisation. [German patent

Energy Technology Data Exchange (ETDEWEB)

Kruse, F; Maus, W

1979-07-19

The invention concerns a material in pellet formm for desulphurisation of gases with a high CO/sub 2/ content, particularly sewer gas, where the material consists mainly of iron oxide hydrate, to which a loosening material, binding material and additional materials such as calcium carbonate and furnace slack are added, and which contains combined water. Chemically active iron oxide hydrate material such as material which occurs as remnant in pyrogenic bauxite treatment in aluminium manufacture, bog iron ore, material from water works and similar materials can be used as iron oxide hydrate. Sawdust or turf can be used as loosening material to increase the open porosity.

Quantum chemical analysis of the structures of MgSO4 hydrates

NARCIS (Netherlands)

Iype, E.; Ozen, C.; Nedea, S.V.; Rindt, C.C.M.; Zondag, H.A.

2012-01-01

Magnesium sulfate salts can form hydrated compounds with up to seven degree of hydration with an energy exchange of the order of 2.8GJ/m3 [1]. In addition, this salt is abundant in nature and thus this material is a potential candidate for storing energy in seasonal heat storage systems. One of the

Challenges, uncertainties, and issues facing gas production from gas-hydrate deposits

Science.gov (United States)

Moridis, G.J.; Collett, T.S.; Pooladi-Darvish, M.; Hancock, S.; Santamarina, C.; Boswel, R.; Kneafsey, T.; Rutqvist, J.; Kowalsky, M.B.; Reagan, M.T.; Sloan, E.D.; Sum, A.K.; Koh, C.A.

2011-01-01

The current paper complements the Moridis et al. (2009) review of the status of the effort toward commercial gas production from hydrates. We aim to describe the concept of the gas-hydrate (GH) petroleum system; to discuss advances, requirements, and suggested practices in GH prospecting and GH deposit characterization; and to review the associated technical, economic, and environmental challenges and uncertainties, which include the following: accurate assessment of producible fractions of the GH resource; development of methods for identifying suitable production targets; sampling of hydrate-bearing sediments (HBS) and sample analysis; analysis and interpretation of geophysical surveys of GH reservoirs; well-testing methods; interpretation of well-testing results; geomechanical and reservoir/well stability concerns; well design, operation, and installation; field operations and extending production beyond sand-dominated GH reservoirs; monitoring production and geomechanical stability; laboratory investigations; fundamental knowledge of hydrate behavior; the economics of commercial gas production from hydrates; and associated environmental concerns. ?? 2011 Society of Petroleum Engineers.

Hydration of refractory cements, with spinel phase generated in-situ

International Nuclear Information System (INIS)

Lavat, A.E; Grasselli, M.C; Giuliodori Lovecchio, E

2008-01-01

High alumina refractory materials with additions of synthetic spinel (MgAl 2 O 4 ) have good thermo mechanical and attack from slag properties, which are useful in many technological applications. The spinel phase generated in-situ, MA, has proven to be a suitable and economic alternative to the use of sintered or electrocast spinels. Prior studies have established synthesis conditions for refractory cements with the spinel phase generated in-situ (CCAMA) starting with alumina mixtures and Buenos Aires dolomites. The binding properties of the aluminous cements depend on the hydrated calcium aluminates that form in the setting and hardening stages of the pastes. To avoid breaks, the refractory material must undergo programmed heating before reaching the serviceable temperature. It should also include the present phases and the transformations that occur at different temperatures. In this context knowledge about the green mineral composition and its response to an increase in temperature is especially important. This work presents studies to define the composition of CCAMA cement mortars at different hydration ages, and to estimate phase proportions and behavior during dehydration. DRX and FTIR techniques are applied in order to follow the structural changes that take place during the hydration process. The evolution of the dehydration is also studied, mostly using FTIR. The mortars were prepared with a water/cement ration of 0.5, recommended for this kind of work. The hydration was carried out at room temperature and samples were analyzed at the following ages: 15 min.; 1 h.; 1, 3, 7, 14, 28, 60 and 90 days. With the results the evolution of the phases as a function of the age of the hydration were studied. The main hydrate that was formed was CAH 10 , with a significantly increased proportion during the first 14 days of hydration. Its carbonation was also observed by the presence of calcium carboaluminates and the formation of gibbsite. The MA phase is also

Effect of MXene (Nano-Ti3C2 on Early-Age Hydration of Cement Paste

Directory of Open Access Journals (Sweden)

Haibin Yin

2015-01-01

Full Text Available As a new two-dimensional material, MXene (nano-Ti3C2 has been widely applied in many fields, especially for reinforced composite materials. In this paper, mechanical testing, X-ray diffraction (XRD, hydration heat, scanning electron microscope (SEM, and EDS analysis were used to analyze the impact of MXene on cement hydration properties. The obtained results revealed that (a MXene could greatly improve the early compressive strength of cement paste with 0.04 wt% concentration, (b the phase type of early-age hydration products has not been changed after the addition of MXene, (c hydration exothermic rate within 72 h has small difference at different amount of MXene, and (d morphologies of hydration products were varied with the dosage of MXene, a lot of tufted ettringites appeared in 3 d hydration products when the content of MXene was 0.04 wt%, which will have a positive effect on improving the early mechanical properties of cement paste. MXene has inhibited the Portland cement hydration process; the main role of MXene in the cement hydration process is to promote the messy ettringite becoming regular distribution at a node and form network connection structure in the crystals growth process, making the mechanics performance of cement paste significantly improved.

Chemical and mineralogical characterization of two commercial cements and its evolution in function of time

International Nuclear Information System (INIS)

Gutierrez B, O.

2014-01-01

Mineralogical evolution of Portland cement is studied during hydration process using materials characterization techniques as X-ray diffraction (XRD) and scanning electron microscopy (Sem) in order to analyze the changes in the various cement minerals as alite, belite, celite, during processing to the hydrated phases of tobermorite gel, portlandite and ettringite, respectively, in the cement paste setting at different ages (3, 7 and 28 days). It was found that the hydration process occurs differently in each mineral because of their reaction rates or changes they experience in their crystals during processing of anhydrous to hydrated phase. You may notice changes in the appearance of the dough as you go hydration and the formation of tobermorite gel, portlandite and ettringite. (Author)

Nondestructive materials characterization with applications to aerospace materials

CERN Document Server

Nagy, Peter; Rokhlin, Stanislav

2004-01-01

With an emphasis on aircraft materials, this book describes techniques for the material characterization to detect and quantify degradation processes such as corrosion and fatigue. It introduces readers to these techniques based on x-ray, ultrasonic, optical and thermal principles and demonstrates the potential of the techniques for a wide variety of applications concerning aircraft materials, especially aluminum and titanium alloys. The advantages and disadvantages of various techniques are evaluated. An introductory chapter describes the typical degradation mechanisms that must be considered and the microstructure features that have to be detected by NDE methods. Finally, some approaches for making lifetime predictions are discussed. It is suitable as a textbook in special training courses in advanced NDE and aircraft materials characterization.

Impact-limiting materials characterization

International Nuclear Information System (INIS)

Glass, R.E.; Duffey, T.A.; McConnell, P.

1993-01-01

Three types of impact-limiting materials have been characterized which have applications in packages for the transport of radioactive materials. These materials are aluminum honeycombs, polyurethane foams, and aluminum foams. The results of the materials characterization have indicated strengths and weaknesses for each type of material. The polyurethane foams provide good impact limiting ability and excellent thermal insulation. However, they burn when subjected to the regulatory thermal event in the presence of air. The aluminum honeycombs provide excellent impact resistance in specific impact orientations. However, they provide relatively poor resistance to thermal assault. Finally, the aluminum foams exhibit relatively poor impact energy absorption capacities, significant variability in energy absorption, and limited thermal insulation. The development of the figures of merit examined the response of the materials to the impact event with the intent of maximizing the energy absorption of the materials with respect to either the volume or mass of the materials. Three figures of merit will be presented for the structural response. The figure of merit for the thermal event is based on minimizing the heat flux to the containment boundary. The paper presents a discussion of the test methods, a summary of the data and the figures of merit for each material. (J.P.N.)

Soluble salts addition modifies MgO hydration

International Nuclear Information System (INIS)

Santos, A.M.; Pandolfelli, V.C.; Salomao, R.

2012-01-01

Magnesium oxide (MgO) show great technological interest on refractories due to its high refractoriness, basic slag corrosion resistance and competitive cost. However, the hydration reaction of MgO produces magnesium hydroxide. This reaction generates a significant volumetric expansion that can lead to material breakdown inhibiting its use in refractory castables. This reaction can be affected by several factors such as magnesia source, purity, calcination temperature, pH, CaO/SiO 2 ratio and agitation speed. In the present work, soluble salts (CaCl 2 and MgCl 2 ) were used in MgO aqueous suspensions (caustic and sinter). The results were evaluated by means of techniques of degree of hydration (termogravimetric), Scanning electron microscopy, apparent volumetric expansion and x-ray Diffraction which showed that the degree of hydration was noticeably less to sinter aqueous and the expansive effects were less with the addition of CaCl 2 . (author)

Direct measurement of methane hydrate composition along the hydrate equilibrium boundary

Science.gov (United States)

Circone, S.; Kirby, S.H.; Stern, L.A.

2005-01-01

The composition of methane hydrate, namely nW for CH 4??nWH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nW may show a slight systematic decrease away from this boundary. A hydrate stoichiometry of n W = 5.81-6.10 H2O describes the entire range of measured values, with an average composition of CH4??5.99(??0.07) H2O along the equilibrium boundary. These results, consistent with previously measured values, are discussed with respect to the widely ranging values obtained by thermodynamic analysis. The relatively constant composition of methane hydrate over the geologically relevant pressure and temperature range investigated suggests that in situ methane hydrate compositions may be estimated with some confidence. ?? 2005 American Chemical Society.

Deep Sea Shell Taphonomy: Interactive benthic experiments in hydrate environments of Barkley Canyon, Ocean Networks Canada.

Science.gov (United States)

Best, Mairi; Purser, Autun

2015-04-01

In order to quantify and track the rates and processes of modification of biogenic carbonate in gas hydrate environments, and their possible environmental/ecological correlates, ongoing observations of experimentally deployed specimens are being made using a remotely controlled crawler with camera and sensors. The crawler is connected to NEPTUNE Canada, an 800km, 5-node, regional cabled ocean network across the northern Juan de Fuca Plate, northeastern Pacific, part of Ocean Networks Canada. One of 15 study areas is an environment of exposed hydrate mounds along the wall of Barkley Canyon, at ˜865m water depth. This is the home of a benthic crawler developed by Jacobs University of Germany, who is affectionately known as Wally. Wally is equipped with a range of sensors including cameras, methane sensor, current meter, fluorometer, turbidity meter, CTD, and a sediment microprofiler with probes for oxygen, methane, sulphide, pH, temperature, and conductivity. In conjunction with this sensor suite, a series of experiments have been designed to assess the cycling of biogenic carbon and carbonate in this complex environment. The biota range from microbes, to molluscs, to large fish, and therefore the carbon inputs include both a range of organic carbon compounds as well as the complex materials that are "biogenic carbonate". Controlled experimental specimens were deployed of biogenic carbonate (Mytilus edulis fresh shells) and cellulose (pieces of untreated pine lumber) that had been previously well characterized (photographed, weighed, and numbered, matching valves and lumber kept as controls). Deployment at the sediment/water interface was in such a way to maximize natural burial exhumation cycles but to minimize specimen interaction. 10 replicate specimens of each material were deployed in two treatments: 1) adjacent to a natural life and death assemblage of chemosynthetic bivalves and exposed hydrate on a hydrate mound and 2) on the muddy seafloor at a distance

A Circuit Model of Real Time Human Body Hydration.

Science.gov (United States)

Asogwa, Clement Ogugua; Teshome, Assefa K; Collins, Stephen F; Lai, Daniel T H

2016-06-01

Changes in human body hydration leading to excess fluid losses or overload affects the body fluid's ability to provide the necessary support for healthy living. We propose a time-dependent circuit model of real-time human body hydration, which models the human body tissue as a signal transmission medium. The circuit model predicts the attenuation of a propagating electrical signal. Hydration rates are modeled by a time constant τ, which characterizes the individual specific metabolic function of the body part measured. We define a surrogate human body anthropometric parameter θ by the muscle-fat ratio and comparing it with the body mass index (BMI), we find theoretically, the rate of hydration varying from 1.73 dB/min, for high θ and low τ to 0.05 dB/min for low θ and high τ. We compare these theoretical values with empirical measurements and show that real-time changes in human body hydration can be observed by measuring signal attenuation. We took empirical measurements using a vector network analyzer and obtained different hydration rates for various BMI, ranging from 0.6 dB/min for 22.7 [Formula: see text] down to 0.04 dB/min for 41.2 [Formula: see text]. We conclude that the galvanic coupling circuit model can predict changes in the volume of the body fluid, which are essential in diagnosing and monitoring treatment of body fluid disorder. Individuals with high BMI would have higher time-dependent biological characteristic, lower metabolic rate, and lower rate of hydration.

Gas Hydrate Research Database and Web Dissemination Channel

Energy Technology Data Exchange (ETDEWEB)

Micheal Frenkel; Kenneth Kroenlein; V Diky; R.D. Chirico; A. Kazakow; C.D. Muzny; M. Frenkel

2009-09-30

To facilitate advances in application of technologies pertaining to gas hydrates, a United States database containing experimentally-derived information about those materials was developed. The Clathrate Hydrate Physical Property Database (NIST Standard Reference Database {number_sign} 156) was developed by the TRC Group at NIST in Boulder, Colorado paralleling a highly-successful database of thermodynamic properties of molecular pure compounds and their mixtures and in association with an international effort on the part of CODATA to aid in international data sharing. Development and population of this database relied on the development of three components of information-processing infrastructure: (1) guided data capture (GDC) software designed to convert data and metadata into a well-organized, electronic format, (2) a relational data storage facility to accommodate all types of numerical and metadata within the scope of the project, and (3) a gas hydrate markup language (GHML) developed to standardize data communications between 'data producers' and 'data users'. Having developed the appropriate data storage and communication technologies, a web-based interface for both the new Clathrate Hydrate Physical Property Database, as well as Scientific Results from the Mallik 2002 Gas Hydrate Production Research Well Program was developed and deployed at http://gashydrates.nist.gov.

Gas hydrate in nature

Science.gov (United States)

Ruppel, Carolyn D.

2018-01-17

Gas hydrate is a naturally occurring, ice-like substance that forms when water and gas combine under high pressure and at moderate temperatures. Methane is the most common gas present in gas hydrate, although other gases may also be included in hydrate structures, particularly in areas close to conventional oil and gas reservoirs. Gas hydrate is widespread in ocean-bottom sediments at water depths greater than 300–500 meters (m; 984–1,640 feet [ft]) and is also present in areas with permanently frozen ground (permafrost). Several countries are evaluating gas hydrate as a possible energy resource in deepwater or permafrost settings. Gas hydrate is also under investigation to determine how environmental change may affect these deposits.

Preparation and Thermal Properties of Eutectic Hydrate Salt Phase Change Thermal Energy Storage Material

Directory of Open Access Journals (Sweden)

Lin Liang

2018-01-01

Full Text Available In this study, a new cold storage phase change material eutectic hydrate salt (K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O was prepared, modified, and tested. The modification was performed by adding a nucleating agent and thickener. The physical properties such as viscosity, surface tension, cold storage characteristics, supercooling, and the stability during freeze-thaw cycles were studied. Results show that the use of nucleating agents, such as sodium tetraborate, sodium fluoride, and nanoparticles, are effective. The solidification temperature and latent heat of these materials which was added with 0, 3, and 5 wt% thickeners were −11.9, −10.6, and −14.8°C and 127.2, 118.6, 82.56 J/g, respectively. Adding a nucleating agent can effectively improve the nucleation rate and nucleation stability. Furthermore, increasing viscosity has a positive impact on the solidification rate, supercooling, and the stability during freeze-thaw cycles.

Gulf of Mexico Gas Hydrate Joint Industry Project Leg II logging-while-drilling data acquisition and analysis

Science.gov (United States)

Collett, Timothy S.; Lee, Wyung W.; Zyrianova, Margarita V.; Mrozewski, Stefan A.; Guerin, Gilles; Cook, Ann E.; Goldberg, Dave S.

2012-01-01

One of the objectives of the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II (GOM JIP Leg II) was the collection of a comprehensive suite of logging-while-drilling (LWD) data within gas-hydrate-bearing sand reservoirs in order to make accurate estimates of the concentration of gas hydrates under various geologic conditions and to understand the geologic controls on the occurrence of gas hydrate at each of the sites drilled during this expedition. The LWD sensors just above the drill bit provided important information on the nature of the sediments and the occurrence of gas hydrate. There has been significant advancements in the use of downhole well-logging tools to acquire detailed information on the occurrence of gas hydrate in nature: From using electrical resistivity and acoustic logs to identify gas hydrate occurrences in wells to where wireline and advanced logging-while-drilling tools are routinely used to examine the petrophysical nature of gas hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. Recent integrated sediment coring and well-log studies have confirmed that electrical resistivity and acoustic velocity data can yield accurate gas hydrate saturations in sediment grain supported (isotropic) systems such as sand reservoirs, but more advanced log analysis models are required to characterize gas hydrate in fractured (anisotropic) reservoir systems. In support of the GOM JIP Leg II effort, well-log data montages have been compiled and presented in this report which includes downhole logs obtained from all seven wells drilled during this expedition with a focus on identifying and characterizing the potential gas-hydrate-bearing sedimentary section in each of the wells. Also presented and reviewed in this report are the gas-hydrate saturation and sediment porosity logs for each of the wells as calculated from available downhole well logs.

Properties and characterization of modern materials

CERN Document Server

Altenbach, Holm

2017-01-01

This book focuses on robust characterization and prediction methods for materials in technical applications as well as the materials’ safety features during operation. In particular, it presents methods for reliably predicting material properties, an aspect that is becoming increasingly important as engineering materials are pushed closer and closer to their limits to boost the performance of machines and structures. To increase their engineering value, components are now designed under the consideration of their multiphysical properties and functions, which requires much more intensive investigation and characterization of these materials. The materials covered in this monograph range from metal-based groups such as lightweight alloys, to advanced high-strength steels and modern titanium alloys. Furthermore, a wide range of polymers and composite materials (e.g. with micro- and nanoparticles or fibres) is covered. The book explores methods for property prediction from classical mechanical characterization-...

Full quantitative phase analysis of hydrated lime using the Rietveld method

Energy Technology Data Exchange (ETDEWEB)

Lassinantti Gualtieri, Magdalena, E-mail: magdalena.gualtieri@unimore.it [Dipartimento Ingegneria dei Materiali e dell' Ambiente, Universita Degli Studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41100 Modena (Italy); Romagnoli, Marcello; Miselli, Paola; Cannio, Maria [Dipartimento Ingegneria dei Materiali e dell' Ambiente, Universita Degli Studi di Modena e Reggio Emilia, Via Vignolese 905/a, I-41100 Modena (Italy); Gualtieri, Alessandro F. [Dipartimento di Scienze della Terra, Universita Degli Studi di Modena e Reggio Emilia, I-41100 Modena (Italy)

2012-09-15

Full quantitative phase analysis (FQPA) using X-ray powder diffraction and Rietveld refinements is a well-established method for the characterization of various hydraulic binders such as Portland cement and hydraulic limes. In this paper, the Rietveld method is applied to hydrated lime, a non-hydraulic traditional binder. The potential presence of an amorphous phase in this material is generally ignored. Both synchrotron radiation and a conventional X-ray source were used for data collection. The applicability of the developed control file for the Rietveld refinements was investigated using samples spiked with glass. The results were cross-checked by other independent methods such as thermal and chemical analyses. The sample microstructure was observed by transmission electron microscopy. It was found that the consistency between the different methods was satisfactory, supporting the validity of FQPA for this material. For the samples studied in this work, the amount of amorphous material was in the range 2-15 wt.%.

Full quantitative phase analysis of hydrated lime using the Rietveld method

International Nuclear Information System (INIS)

Lassinantti Gualtieri, Magdalena; Romagnoli, Marcello; Miselli, Paola; Cannio, Maria; Gualtieri, Alessandro F.

2012-01-01

Full quantitative phase analysis (FQPA) using X-ray powder diffraction and Rietveld refinements is a well-established method for the characterization of various hydraulic binders such as Portland cement and hydraulic limes. In this paper, the Rietveld method is applied to hydrated lime, a non-hydraulic traditional binder. The potential presence of an amorphous phase in this material is generally ignored. Both synchrotron radiation and a conventional X-ray source were used for data collection. The applicability of the developed control file for the Rietveld refinements was investigated using samples spiked with glass. The results were cross-checked by other independent methods such as thermal and chemical analyses. The sample microstructure was observed by transmission electron microscopy. It was found that the consistency between the different methods was satisfactory, supporting the validity of FQPA for this material. For the samples studied in this work, the amount of amorphous material was in the range 2–15 wt.%.

Monitoring early hydration of reinforced concrete structures using structural parameters identified by piezo sensors via electromechanical impedance technique

Science.gov (United States)

Talakokula, Visalakshi; Bhalla, Suresh; Gupta, Ashok

2018-01-01

Concrete is the most widely used material in civil engineering construction. Its life begins when the hydration process is activated after mixing the cement granulates with water. In this paper, a non-dimensional hydration parameter, obtained from piezoelectric ceramic (PZT) patches bonded to rebars embedded inside concrete, is employed to monitor the early age hydration of concrete. The non-dimensional hydration parameter is derived from the equivalent stiffness determined from the piezo-impedance transducers using the electro-mechanical impedance (EMI) technique. The focus of the study is to monitor the hydration process of cementitious materials commencing from the early hours and continue till 28 days using single non-dimensional parameter. The experimental results show that the proposed piezo-based non-dimensional hydration parameter is very effective in monitoring the early age hydration, as it has been derived from the refined structural impedance parameters, obtained by eliminating the PZT contribution, and using both the real and imaginary components of the admittance signature.

[Skin hydration and hydrating products].

Science.gov (United States)

Duplan, H; Nocera, T

2018-05-01

One of the skin's principal functions is to protect the body against its environment by maintaining an effective epidermal barrier, not only against external factors, but also to prevent water loss from the body. Indeed, water homeostasis is vital for the normal physiological functioning of skin. Hydration levels affect not only visible microscopic parameters such as the suppleness and softness of skin, but also molecular parameters, enzyme activities and cellular signalling within the epidermis. The body is continually losing some of its water, but this phenomenon is limited and the optimal hydration gradient in skin is ensured via a set of sophisticated regulatory processes that rely on the functional and dynamic properties of the uppermost level of the skin consisting of the stratum corneum. The present article brings together data recently acquired in the fields of skin hydration and the characterisation of dehydrated or dry skin, whether through study of the regulatory processes involved or as a result of changes in the techniques used for in situ measurement, and thus in optimisation of management. Copyright © 2018. Published by Elsevier Masson SAS.

Methane accumulation and forming high saturations of methane hydrate in sandy sediments

Energy Technology Data Exchange (ETDEWEB)

Uchida, T.; Waseda, A. [JAPEX Research Center, Chiba (Japan); Fujii, T. [Japan Oil, Gas and Metals National Corp., Chiba (Japan). Upstream Technology Unit

2008-07-01

Methane supplies for marine gas hydrates are commonly attributed to the microbial conversion of organic materials. This study hypothesized that methane supplies were related to pore water flow behaviours and microscopic migration in intergranular pore systems. Sedimentology and geochemistry analyses were performed on sandy core samples taken from the Nankai trough and the Mallik gas hydrate test site in the Mackenzie Delta. The aim of the study was to determine the influence of geologic and sedimentolic controls on the formation and preservation of natural gas hydrates. Grain size distribution curves indicated that gas hydrate saturations of up to 80 per cent in pore volume occurred throughout the hydrate-dominant sand layers in the Nankai trough and Mallik areas. Water permeability measurements showed that the highly gas hydrate-saturated sands have a permeability of a few millidarcies. Pore-space gas hydrates occurred primarily in fine and medium-grained sands. Core temperature depression, core observations, and laboratory analyses of the hydrates confirmed the pore-spaces as intergranular pore fillings. Results of the study suggested that concentrations of gas hydrates may require a pore space large enough to occur within a host sediments, and that the distribution of porous and coarser-grained sandy sediments is an important factor in controlling the occurrence of gas hydrates. 11 refs., 4 figs.

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample.

Science.gov (United States)

Muraoka, Michihiro; Susuki, Naoko; Yamaguchi, Hiroko; Tsuji, Tomoya; Yamamoto, Yoshitaka

2016-03-21

Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future energy resources and energy storage media. To develop a method for gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates. The thermal properties' measurements of samples comprising sand, water, methane, and MH are difficult because the melting heat of MH may affect the measurements. To solve this problem, we performed thermal properties' measurements at supercooled conditions during MH formation. The measurement protocol, calculation method of the saturation change, and tips for thermal constants' analysis of the sample using transient plane source techniques are described here. The effect of the formation heat of MH on measurement is very small because the gas hydrate formation rate is very slow. This measurement method can be applied to the thermal properties of the gas hydrate-water-guest gas system, which contains hydrogen, CO2, and ozone hydrates, because the characteristic low formation rate of gas hydrate is not unique to MH. The key point of this method is the low rate of phase transition of the target material. Hence, this method may be applied to other materials having low phase-transition rates.

Low residual diet and hydration improving double contrast examination of the colon

International Nuclear Information System (INIS)

Virkki, R.; Maekelae, P.

1983-01-01

Light food diet and low residual diet with hydration, both combined with Proctosal and Bisacodyl cleansing, were compared in 268 patients in the preparation of the colon for double contrast examination. Low residual diet with hydration resulted in significantly less residual fecal material, no flocculation of the barium coating and significantly denser mucosal coating. The examination had to be repeated more often (8.6%) after light food diet than after low residual diet with hydration (1.7%), but there was no statistically significant difference in the diagnostic accuracy. The hydration is important in avoiding patient discomforts and flocculation of the barium coating. Despite the use of laxatives, a strict diet restriction is needed to obtain consistently clean colon. (orig.)

Novel understanding of calcium silicate hydrate from dilute hydration

KAUST Repository

Zhang, Lina; Yamauchi, Kazuo; Li, Zongjin; Zhang, Xixiang; Ma, Hongyan; Ge, Shenguang

2017-01-01

The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10

Historical methane hydrate project review

Science.gov (United States)

Collett, Timothy; Bahk, Jang-Jun; Frye, Matt; Goldberg, Dave; Husebo, Jarle; Koh, Carolyn; Malone, Mitch; Shipp, Craig; Torres, Marta

2013-01-01

In 1995, U.S. Geological Survey made the first systematic assessment of the volume of natural gas stored in the hydrate accumulations of the United States. That study, along with numerous other studies, has shown that the amount of gas stored as methane hydrates in the world greatly exceeds the volume of known conventional gas resources. However, gas hydrates represent both a scientific and technical challenge and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of gas hydrates in nature, (2) assessing the volume of natural gas stored within various gas hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural gas hydrates, and (5) analyzing the effects of methane hydrate on drilling safety.Methane hydrates are naturally occurring crystalline substances composed of water and gas, in which a solid water-­‐lattice holds gas molecules in a cage-­‐like structure. The gas and water becomes a solid under specific temperature and pressure conditions within the Earth, called the hydrate stability zone. Other factors that control the presence of methane hydrate in nature include the source of the gas included within the hydrates, the physical and chemical controls on the migration of gas with a sedimentary basin containing methane hydrates, the availability of the water also included in the hydrate structure, and the presence of a suitable host sediment or “reservoir”. The geologic controls on the occurrence of gas hydrates have become collectively known as the “methane hydrate petroleum system”, which has become the focus of numerous hydrate research programs.Recognizing the importance of methane hydrate research and the need for a coordinated

X-ray Tomography and Impregnation Methods to Analyze Pore Space Hetrerogeneities at the Hydrated State

International Nuclear Information System (INIS)

Pret, D.; Ferrage, E.; Tertre, E.; Robinet, J.C.; Faurel, M.; Hubert, F.; Pelletier, M.; Bihannic, I.

2013-01-01

environmental conditions and preparations are used. In case of methods able to deal with wet atmospheres and nanometre resolution, sub-sampling millimetre or micrometre size hydrated samples without inducing shearing or fractures is also not still proven. Optimization of impregnation procedure for water saturated clay samples still plays a pivotal role for applying the most advanced imaging techniques at the nanometre scale. In addition, natural clay rocks in sedimentary basins or engineered barriers in deep repositories could not swell or shrink by changing their macroscopic volume. Such case corresponds to constrained swelling conditions that implies a distribution of pore and water highly contrasting with dry state and hydrated state in free swelling conditions. Moreover, swelling rate could potentially be limited down to the crystal scale. As probing in-situ the organization of hydrated and compacted clay materials into an odometer set-up is challenging, it is really poorly documented in literature. Note that opening an odometer setup and analyzing a sample is not a constrained swelling condition: immediate swelling and change of pore space occurs. Natural clayey rocks in sedimentary basins display additional spatial variations of mineral and porosity distributions with contrasted spatial frequencies or gradual evolutions due to sedimentation cycles, temporal evolutions of climate, variations of sources, diagenesis, etc. At the scale of a laboratory sample, geological history still imposes a heterogeneous spatial distribution of mineral and pore space down-scaling to the crystal scale. Localizing samples with a millimetre size or less against the heterogeneities encountered at larger scale is thus important before analyzing it with a nanometre resolution. The best is to follow a continuous down-scaling approach all along the characterization of the organization, keeping the sample in a similar state between each technique. Here we propose a method to fully impregnate up to

Hydraulic and Mechanical Effects from Gas Hydrate Conversion and Secondary Gas Hydrate Formation during Injection of CO2 into CH4-Hydrate-Bearing Sediments

Science.gov (United States)

Bigalke, N.; Deusner, C.; Kossel, E.; Schicks, J. M.; Spangenberg, E.; Priegnitz, M.; Heeschen, K. U.; Abendroth, S.; Thaler, J.; Haeckel, M.

2014-12-01

The injection of CO2 into CH4-hydrate-bearing sediments has the potential to drive natural gas production and simultaneously sequester CO2 by hydrate conversion. The process aims at maintaining the in situ hydrate saturation and structure and causing limited impact on soil hydraulic properties and geomechanical stability. However, to increase hydrate conversion yields and rates it must potentially be assisted by thermal stimulation or depressurization. Further, secondary formation of CO2-rich hydrates from pore water and injected CO2 enhances hydrate conversion and CH4 production yields [1]. Technical stimulation and secondary hydrate formation add significant complexity to the bulk conversion process resulting in spatial and temporal effects on hydraulic and geomechanical properties that cannot be predicted by current reservoir simulation codes. In a combined experimental and numerical approach, it is our objective to elucidate both hydraulic and mechanical effects of CO2 injection and CH4-CO2-hydrate conversion in CH4-hydrate bearing soils. For the experimental approach we used various high-pressure flow-through systems equipped with different online and in situ monitoring tools (e.g. Raman microscopy, MRI and ERT). One particular focus was the design of triaxial cell experimental systems, which enable us to study sample behavior even during large deformations and particle flow. We present results from various flow-through high-pressure experimental studies on different scales, which indicate that hydraulic and geomechanical properties of hydrate-bearing sediments are drastically altered during and after injection of CO2. We discuss the results in light of the competing processes of hydrate dissociation, hydrate conversion and secondary hydrate formation. Our results will also contribute to the understanding of effects of temperature and pressure changes leading to dissociation of gas hydrates in ocean and permafrost systems. [1] Deusner C, Bigalke N, Kossel E

Synthesis, formation mechanism and sensing properties of WO3 hydrate nanowire netted-spheres

International Nuclear Information System (INIS)

Yan, Aihua; Xie, Changsheng; Zeng, Dawen; Cai, Shuizhou; Hu, Mulin

2010-01-01

Tungsten oxide hydrate nanowire netted-spheres were successfully synthesized in the glycol solution using a facile solvothermal approach. The nanowires with uniform diameter of 4-6 nm are actually a kind of tungsten oxide hydrate/surfactant hybrid materials. The influence of surfactant, solvent, time and temperature on tailoring morphology was investigated in detail. The possible formation process of WO 3 hydrate nanowire netted-sphere was proposed. Sensing properties of such WO 3 hydrate sensor show that the desirable sensing characteristics towards 100 ppm ammonia gas at 320 o C were obtained, such as rapid response (18.3 s), high sensitivity, good reproducibility and stability.

Strength Estimation for Hydrate-Bearing Sediments From Direct Shear Tests of Hydrate-Bearing Sand and Silt

Science.gov (United States)

Liu, Zhichao; Dai, Sheng; Ning, Fulong; Peng, Li; Wei, Houzhen; Wei, Changfu

2018-01-01

Safe and economic methane gas production, as well as the replacement of methane while sequestering carbon in natural hydrate deposits, requires enhanced geomechanical understanding of the strength and volume responses of hydrate-bearing sediments during shear. This study employs a custom-made apparatus to investigate the mechanical and volumetric behaviors of carbon dioxide hydrate-bearing sediments subjected to direct shear. The results show that both peak and residual strengths increase with increased hydrate saturation and vertical stress. Hydrate contributes mainly the cohesion and dilatancy constraint to the peak strength of hydrate-bearing sediments. The postpeak strength reduction is more evident and brittle in specimens with higher hydrate saturation and under lower stress. Significant strength reduction after shear failure is expected in silty sediments with high hydrate saturation Sh ≥ 0.65. Hydrate contribution to the residual strength is mainly by increasing cohesion at low hydrate saturation and friction at high hydrate saturation. Stress state and hydrate saturation are dominating both the stiffness and the strength of hydrate-bearing sediments; thus, a wave velocity-based peak strength prediction model is proposed and validated, which allows for precise estimation of the shear strength of hydrate-bearing sediments through acoustic logging data. This method is advantageous to geomechanical simulators, particularly when the experimental strength data of natural samples are not available.

Gas hydrate concentration and characteristics within Hydrate Ridge inferred from multicomponent seismic reflection data

Science.gov (United States)

Kumar, Dhananjay; Sen, Mrinal K.; Bangs, Nathan L.

2007-12-01

A seismic experiment composed of streamer and ocean bottom seismometer (OBS) surveys was conducted in the summer of 2002 at southern Hydrate Ridge, offshore Oregon, to map the gas hydrate distribution within the hydrate stability zone. Gas hydrate concentrations within the reservoir can be estimated with P wave velocity (Vp); however, we can further constrain gas hydrate concentrations using S wave velocity (Vs), and use Vs through its relationship to Vp (Vp/Vs) to reveal additional details such as gas hydrate form within the matrix (i.e., hydrate cements the grains, becomes part of the matrix frame or floats in pore space). Both Vp and Vs can be derived simultaneously by inverting multicomponent seismic data. In this study, we use OBS data to estimate seismic velocities where both gas hydrate and free gas are present in the shallow sediments. Once Vp and Vs are estimated, they are simultaneously matched with modeled velocities to estimate the gas hydrate concentration. We model Vp using an equation based on a modification of Wood's equation that incorporates an appropriate rock physics model and Vs using an empirical relation. The gas hydrate concentration is estimated to be up to 7% of the rock volume, or 12% of the pore space. However, Vp and Vs do not always fit the model simultaneously. Vp can vary substantially more than Vs. Thus we conclude that a model, in which higher concentrations of hydrate do not affect shear stiffness, is more appropriate. Results suggest gas hydrates form within the pore space of the sediments and become part of the rock framework in our survey area.

Material Response Characterization

Science.gov (United States)

1977-08-01

models fit to vertical UX and TX data and a mean stress tension cutoff criterion. Because tests on the Kayenta sands one materials had revealed a definite...parameters. 9 This data characterizing the anisotropic response of the upper 30 feet of Kayenta material should not just be filed away; it should be used...9. Johnson, J. N., et al, "Anisotropic Mechanical Properties of Kayenta Sandstone (MIXED COMPANY Site) for Ground Motion Calculations," Terra Tek TR

A thermodynamic approach to the hydration of sulphate-resisting Portland cement

International Nuclear Information System (INIS)

Lothenbach, Barbara; Wieland, Erich

2006-01-01

A thermodynamic approach is used to model changes in the hydrate assemblage and the composition of the pore solution during the hydration of calcite-free and calcite-containing sulphate-resisting Portland cement CEM I 52.5 N HTS. Modelling is based on thermodynamic data for the hydration products and calculated hydration rates for the individual clinker phases, which are used as time-dependent input parameters. Model predictions compare well with the composition of the hydrate assemblage as observed by TGA and semi-quantitative XRD and with the experimentally determined compositions of the pore solutions. The calculations show that in the presence of small amounts of calcite typically associated with Portland cement, C-S-H, portlandite, ettringite and calcium monocarbonate are the main hydration products. In the absence of calcite in the cement, however, siliceous hydrogarnet instead of calcium monocarbonate is observed to precipitate. The use of a higher water-to-cement ratio for the preparation of a calcite-containing cement paste has a minor effect on the composition of the hydrate assemblage, while it significantly changes the composition of the pore solution. In particular, lower pH value and higher Ca concentrations appear that could potentially influence the solubility and uptake of heavy metals and anions by cementitious materials

High-temperature CO2 capture cycles of hydrated limestone prepared with aluminum (hydr)oxides derived from kaolin

International Nuclear Information System (INIS)

Wang, Ke; Zhao, Pengfei; Guo, Xin; Han, Dongtai; Chao, Yang

2014-01-01

Highlights: • Hydrated limestone exhibited a higher reactivity and stability. • Microstructure of hydrated limestone was significantly improved. • Hydrated limestone still suffered less loss-incapacity. • Hydrated limestone sorbents with kaolin-based binders were prepared and characterized. • Sorbents prepared from hydrated limestone and Al(OH) 3 binder are a promising sorbent. - Abstract: A simple and convenient process was used to improve the utilization of natural limestone and kaolin for calcium looping technology and environmental applications. The calcined natural limestone modified with the distilled water (denoted as Limestone-W), was systematically studied and compared with the other CaO sorbents (calcium acetate, calcium D-gluconate and calcined natural limestone). These CaO-based sorbents were tested for their CO 2 capture behavior through 20 carbonation/calcination cycles in a thermo-gravimetric analyzer (TGA). Their morphology, pore structure and phase composition before and after carbonation/calcination cycles were determined by scanning electron microscopy, nitrogen adsorption, and X-ray diffraction. The first-cycle and multicycle sorption results revealed that the Limestone-W sorbent exhibited a relatively faster reaction rate and higher cyclic CO 2 capture. The characterization data indicated that the Limestone-W was composed of a special calcium oxide structure with lower crystalline and higher porosity nanoparticles, which appeared to be the main reasons for its higher CO 2 capture capability. However, the Limestone-W still suffered loss of reactivity, even though it was less pronounced than the other CaO sorbent. To avoid this unfavorable effect, a thermally stable inert material (aluminum hydroxide derived from kaolin) was incorporated into the Limestone-W structure. This new sorbent revealed higher stability because the formation of a stable framework of Ca 12 Al 14 O 33 particles hindered densification and sintering of the CaO phase

Hydration dynamics near a model protein surface

International Nuclear Information System (INIS)

Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

2003-01-01

The evolution of water dynamics from dilute to very high concentration solutions of a prototypical hydrophobic amino acid with its polar backbone, N-acetyl-leucine-methylamide (NALMA), is studied by quasi-elastic neutron scattering and molecular dynamics simulation for both the completely deuterated and completely hydrogenated leucine monomer. We observe several unexpected features in the dynamics of these biological solutions under ambient conditions. The NALMA dynamics shows evidence of de Gennes narrowing, an indication of coherent long timescale structural relaxation dynamics. The translational water dynamics are analyzed in a first approximation with a jump diffusion model. At the highest solute concentrations, the hydration water dynamics is significantly suppressed and characterized by a long residential time and a slow diffusion coefficient. The analysis of the more dilute concentration solutions takes into account the results of the 2.0M solution as a model of the first hydration shell. Subtracting the first hydration layer based on the 2.0M spectra, the translational diffusion dynamics is still suppressed, although the rotational relaxation time and residential time are converged to bulk-water values. Molecular dynamics analysis shows spatially heterogeneous dynamics at high concentration that becomes homogeneous at more dilute concentrations. We discuss the hydration dynamics results of this model protein system in the context of glassy systems, protein function, and protein-protein interfaces

Analytical nondestructive evaluation for materials characterization

International Nuclear Information System (INIS)

Raj, Baldev

1993-01-01

Science and technology of nondestructive testing and evaluation has contributed immensely to the safety and productivity of industrial plants. In recent years, nondestructive evaluation (NDE) has emerged as a frontline research area of equal if not greater technological relevance, for materials characterization as well. A comprehensive range of techniques from qualitative nondestructive testing for quality control of engineering products and materials to quantitative NDE for materials characterization is being used by the engineering industry and materials researchers, for better understanding of the manufacturing practices and materials behaviour. Quantitative NDE is considered essential for ensuring fitness for purpose at the start of the life in case the component has been designed using fracture mechanics parameters. Quantitative NDE is also vital for assessing degradation of material during service. Moreover, quantitative NDE enables characterization of dynamics of certain phenomenon (not achievable by destructive test methodologies) leading to better understanding of the performance of materials in relation to unavoidable defects in the materials. As the next logical step, the need for an analytical approach to NDE is felt. The need and motivation for such an approach is addressed and the means to achieve this objective are identified. It is argued that analytical NDE is essential to meet the challenges of characterization, intelligent processing of materials and life prediction of components and plants. These requirements are of significant importance in the context of recent developments in materials engineering, and for enhancing the competitive advantage of Indian engineering industry in the international market. (author). 9 refs., 3 figs

Controls on Gas Hydrate Formation and Dissociation

Energy Technology Data Exchange (ETDEWEB)

Miriam Kastner; Ian MacDonald

2006-03-03

The main objectives of the project were to monitor, characterize, and quantify in situ the rates of formation and dissociation of methane hydrates at and near the seafloor in the northern Gulf of Mexico, with a focus on the Bush Hill seafloor hydrate mound; to record the linkages between physical and chemical parameters of the deposits over the course of one year, by emphasizing the response of the hydrate mound to temperature and chemical perturbations; and to document the seafloor and water column environmental impacts of hydrate formation and dissociation. For these, monitoring the dynamics of gas hydrate formation and dissociation was required. The objectives were achieved by an integrated field and laboratory scientific study, particularly by monitoring in situ formation and dissociation of the outcropping gas hydrate mound and of the associated gas-rich sediments. In addition to monitoring with the MOSQUITOs, fluid flow rates and temperature, continuously sampling in situ pore fluids for the chemistry, and imaging the hydrate mound, pore fluids from cores, peepers and gas hydrate samples from the mound were as well sampled and analyzed for chemical and isotopic compositions. In order to determine the impact of gas hydrate dissociation and/or methane venting across the seafloor on the ocean and atmosphere, the overlying seawater was sampled and thoroughly analyzed chemically and for methane C isotope ratios. At Bush hill the pore fluid chemistry varies significantly over short distances as well as within some of the specific sites monitored for 440 days, and gas venting is primarily focused. The pore fluid chemistry in the tub-warm and mussel shell fields clearly documented active gas hydrate and authigenic carbonate formation during the monitoring period. The advecting fluid is depleted in sulfate, Ca Mg, and Sr and is rich in methane; at the main vent sites the fluid is methane supersaturated, thus bubble plumes form. The subsurface hydrology exhibits both

Composite materials processing, applications, characterizations

CERN Document Server

2017-01-01

Composite materials are used as substitutions of metals/traditional materials in aerospace, automotive, civil, mechanical and other industries. The present book collects the current knowledge and recent developments in the characterization and application of composite materials. To this purpose the volume describes the outstanding properties of this class of advanced material which recommend it for various industrial applications.

Evaluation of aging and hydration in natural volcanic glass: magnetic property variations during artificial aging and hydration experiments

Science.gov (United States)

Bowles, J. A.; Patiman, A.

2017-12-01

The recorded geomagnetic field intensity is a function of magnetic mineralogy, grain size, and mineral concentration as well as material stability in nature and during laboratory experiments. Fresh, unhydrated, volcanic glasses are recognized as a nearly ideal natural material for use in paleointensity experiments because they contain the requisite single domain to pseudo-single-domain magnetic particles. Although alteration of magnetic mineralogy can be monitored during the experiments, it is unclear how mineralogy and hence magnetization might change with age as the metastable glass structure relaxes and/or the glass becomes hydrated. Bulk magnetic properties as a function of age show no clear trend, even over hundreds of millions of years. This may be due to the fact that even in fresh, unhydrated glass, there are small-scale differences in magnetic properties due to variation cooling rate or composition variations. Therefore, in order to better understand how magnetic mineralogy evolves with time and hydration, we conducted artificial aging and hydration experiments on fresh, unhydrated rhyolitic (South Deadman Creek, California, 650-yr) and basaltic (Axial Seamount, 2011) end-member glasses. Here, we present the results of artificial aging and hydration experiments. Elevated temperatures accelerate the glass relaxation process in a way that relaxation time decreases with increasing temperature. Aged samples are dry-annealed at 200, 300 and 400 °C for up to 240 days. A second set of samples are hydrated under pressure at 300°C and 450°C. In all cases, isothermal remanent magnetization (IRM) acquisition is monitored to assess changes in the coercivity spectrum and saturation IRM. Preliminary aging results show that in basaltic and rhyolitic glass there is one main peak coercivity at 150 mT and 35 mT, respectively. An increasing sIRM and decreasing peak coercivity trend is observed in basaltic glass whereas no trend is shown in the rhyolitic glass in both

Failure of cement hydrates: freeze-thaw and fracture

Science.gov (United States)

Ioannidou, Katerina; Del Gado, Emanuela; Ulm, Franz-Josef; Pellenq, Roland

Mechanical and viscoelastic behavior of concrete crucially depends on cement hydrates, the ``glue'' of cement. Even more than the atomistic structure, the mesoscale amorphous texture of cement hydrates over hundreds of nanometers plays a crucial role for material properties. We use simulations that combine information of the nano-scale building units of cement hydrates and on their effective interactions, obtained from atomistic simulations and experiments, into a statistical physics framework for aggregating nanoparticles.Our mesoscale model was able to reconcile different experimental results ranging from small-angle neutron scattering, SEM, adsorption/desorption of N2, and water to nanoindentation and gain the new fundamental insights into the microscopic origin of the properties measured. Our results suggest that heterogeneities developed during the early stages of hydration persist in the structure of C-S-H, impacting the rheological and mechanical performance of the hardened cement paste. In this talk I discuss recent investigation on failure mechanism at the mesoscale of hardened cement paste such as freeze-thaw and fracture. Using correlations between local volume fractions and local stress we provide a link between structural and mechanical heterogeneities during the failure mechanisms.

In Situ Raman Analyses of Natural Gas and Gas Hydrates at Hydrate Ridge, Oregon

Science.gov (United States)

Peltzer, E. T.; White, S. N.; Dunk, R. M.; Brewer, P. G.; Sherman, A. D.; Schmidt, K.; Hester, K. C.; Sloan, E. D.

2004-12-01

During a July 2004 cruise to Hydrate Ridge, Oregon, MBARI's sea-going laser Raman spectrometer was used to obtain in situ Raman spectra of natural gas hydrates and natural gas venting from the seafloor. This was the first in situ analysis of gas hydrates on the seafloor. The hydrate spectra were compared to laboratory analyses performed at the Center for Hydrate Research, Colorado School of Mines. The natural gas spectra were compared to MBARI gas chromatography (GC) analyses of gas samples collected at the same site. DORISS (Deep Ocean Raman In Situ Spectrometer) is a laboratory model laser Raman spectrometer from Kaiser Optical Systems, Inc modified at MBARI for deployment in the deep ocean. It has been successfully deployed to depths as great as 3600 m. Different sampling optics provide flexibility in adapting the instrument to a particular target of interest. An immersion optic was used to analyze natural gas venting from the seafloor at South Hydrate Ridge ( ˜780 m depth). An open-bottomed cube was placed over the vent to collect the gas. The immersion optic penetrated the side of the cube as did a small heater used to dissociate any hydrate formed during sample collection. To analyze solid hydrates at both South and North Hydrate Ridge ( ˜590 m depth), chunks of hydrate were excavated from the seafloor and collected in a glass cylinder with a mesh top. A stand-off optic was used to analyze the hydrate inside the cylinder. Due to the partial opacity of the hydrate and the small focal volume of the sampling optic, a precision underwater positioner (PUP) was used to focus the laser spot onto the hydrate. PUP is a stand-alone system with three degrees-of-freedom, capable of moving the DORISS probe head with a precision of 0.1 mm. In situ Raman analyses of the gas indicate that it is primarily methane. This is verified by GC analyses of samples collected from the same site. Other minor constituents (such as CO2 and higher hydrocarbons) are present but may be in

Analysis of vaginal microbicide film hydration kinetics by quantitative imaging refractometry.

Science.gov (United States)

Rinehart, Matthew; Grab, Sheila; Rohan, Lisa; Katz, David; Wax, Adam

2014-01-01

We have developed a quantitative imaging refractometry technique, based on holographic phase microscopy, as a tool for investigating microscopic structural changes in water-soluble polymeric materials. Here we apply the approach to analyze the structural degradation of vaginal topical microbicide films due to water uptake. We implemented transmission imaging of 1-mm diameter film samples loaded into a flow chamber with a 1.5×2 mm field of view. After water was flooded into the chamber, interference images were captured and analyzed to obtain high resolution maps of the local refractive index and subsequently the volume fraction and mass density of film material at each spatial location. Here, we compare the hydration dynamics of a panel of films with varying thicknesses and polymer compositions, demonstrating that quantitative imaging refractometry can be an effective tool for evaluating and characterizing the performance of candidate microbicide film designs for anti-HIV drug delivery.

Hydration rate of obsidian.

Science.gov (United States)

Friedman, I; Long, W

1976-01-30

The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years.

Relationship between diffusivity of water molecules inside hydrating tablets and their drug release behavior elucidated by magnetic resonance imaging.

Science.gov (United States)

Kikuchi, Shingo; Onuki, Yoshinori; Kuribayashi, Hideto; Takayama, Kozo

2012-01-01

We reported previously that sustained release matrix tablets showed zero-order drug release without being affected by pH change. To understand drug release mechanisms more fully, we monitored the swelling and erosion of hydrating tablets using magnetic resonance imaging (MRI). Three different types of tablets comprised of polyion complex-forming materials and a hydroxypropyl methylcellulose (HPMC) were used. Proton density- and diffusion-weighted images of the hydrating tablets were acquired at intervals. Furthermore, apparent self-diffusion coefficient maps were generated from diffusion-weighted imaging to evaluate the state of hydrating tablets. Our findings indicated that water penetration into polyion complex tablets was faster than that into HPMC matrix tablets. In polyion complex tablets, water molecules were dispersed homogeneously and their diffusivity was relatively high, whereas in HPMC matrix tablets, water molecule movement was tightly restricted within the gel. An optimal tablet formulation determined in a previous study had water molecule penetration and diffusivity properties that appeared intermediate to those of polyion complex and HPMC matrix tablets; water molecules were capable of penetrating throughout the tablets and relatively high diffusivity was similar to that in the polyion complex tablet, whereas like the HPMC matrix tablet, it was well swollen. This study succeeded in characterizing the tablet hydration process. MRI provides profound insight into the state of water molecules in hydrating tablets; thus, it is a useful tool for understanding drug release mechanisms at a molecular level.

Review for the improvement of low alkaline cement from viewpoint of hydration control

International Nuclear Information System (INIS)

Imoto, Harutake; Yamamoto, Takeshi; Hironaga, Michihiko

2006-01-01

It is concerns that high pH pore water from cementitious materials will become harmful to barrier system such as bedrock and buffer materials in the radioactive repository. Then sulpho-aluminate type low alkaline cement 'LAC' was developed. But LAC concrete has some problems on its workability and initial crack due to high reactability. It is necessary for LAC to be improved to avoid these problems. In this study, the conventional knowledge on reactability and hardened properties of sulpho-aluminate cement were reviewed from the viewpoint of hydration controlling. From the results, the recipe for the improvement of 'LAC' was investigated. Early hydration of sulpho-aluminate were delayed by the decreasement of calcium hydroxide quantity and increasement of calcium sulphate in cement. Retarder delayed hydration of sulpho-aluminate more than composition of cement. The effect of cement admixture on the early hydration of sulpho-aluminate cement were not reported. Blast furnace slag as cement admixture affect on the long-term hydration and strength development. So, it was guess that sulpho-aluminate type low alkaline cement 'LAC' have good strength development by controlling recipi of additional ratio of blast furnace slag and be-lite content in the sulpho-aluminate cement. (author)

In vivo skin imaging for hydration and micro relief-measurement.

Science.gov (United States)

Kardosova, Z; Hegyi, V

2013-01-01

We present the results of our work with device used for measurement of skin capacitance before and after application of moisturizing creams and results of experiment performed on cellulose filter papers soaked with different solvents. The measurements were performed by a device built on capacitance sensor, which provides an investigator with a capacitance image of the skin. The capacitance values are coded in a range of 256 gray levels then the skin hydration can be characterized using parameters derived from gray level histogram by specific software. The images obtained by device allow a highly precise observation of skin topography. Measuring of skin capacitance brings new, objective, reliable information about topographical, physical and chemical parameters of the skin. The study shows that there is a good correlation between the average grayscale values and skin hydration. In future works we need to complete more comparison studies, interpret the average grayscale values to skin hydration levels and use it for follow-up of dynamics of skin micro-relief and hydration changes (Fig. 6, Ref. 15).

[Prospects for Application of Gases and Gas Hydrates to Cryopreservation].

Science.gov (United States)

Shishova, N V; Fesenko, E E

2015-01-01

In the present review, we tried to evaluate the known properties of gas hydrates and gases participating in the formation of gas hydrates from the point of view of the mechanisms of cryoinjury and cryoprotection, to consider the papers on freezing biological materials in the presence of inert gases, and to analyze the perspectives for the development of this direction. For the purpose, we searched for the information on the physical properties of gases and gas hydrates, compared processes occured during the formation of gas hydrates and water ice, analyzed the influence of the formation and growth of gas hydrates on the structure of biological objects. We prepared a short review on the biological effects of xenon, krypton, argon, carbon dioxide, hydrogen sulfide, and carbon monoxide especially on hypothermal conditions and probable application of these properties in cryopreservation technologies. The description of the existing experiments on cryopreservation of biological objects with the use of gases was analyzed. On the basis of the information we found, the most perspective directions of work in the field of cryopreservation of biological objects with the use of gases were outlined. An attempt was made to forecast the potential problems in this field.

Overview: Nucleation of clathrate hydrates.

Science.gov (United States)

Warrier, Pramod; Khan, M Naveed; Srivastava, Vishal; Maupin, C Mark; Koh, Carolyn A

2016-12-07

Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

Overview: Nucleation of clathrate hydrates

Science.gov (United States)

Warrier, Pramod; Khan, M. Naveed; Srivastava, Vishal; Maupin, C. Mark; Koh, Carolyn A.

2016-12-01

Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

The economics of exploiting gas hydrates

International Nuclear Information System (INIS)

Döpke, Lena-Katharina; Requate, Till

2014-01-01

We investigate the optimal exploitation of methane hydrates, a recent discovery of methane resources under the sea floor, mainly located along the continental margins. Combustion of methane (releasing CO2) and leakage through blow-outs (releasing CH4) contribute to the accumulation of greenhouse gases. A second externality arises since removing solid gas hydrates from the sea bottom destabilizes continental margins and thus increases the risk of marine earthquakes. We show that in such a model three regimes can occur: i) resource exploitation will be stopped in finite time, and some of the resource will stay in situ, ii) the resource will be used up completely in finite time, and iii) the resource will be exhausted in infinite time. We also show how to internalize the externalities by policy instruments. - Highlights: • We set up a model of optimal has hydrate exploitation • We incorporate to types of damages: contribution to global warming and geo-hazards • We characterize optimal exploitation paths and study decentralization with an exploitation tax. • Three regimes can occur: • i) exploitation in finite time and some of the stock remaining in situ, • ii) exploitation in finite time and the resource will be exhausted, • iii) exploitation and exhaustion in infinite time

Reservoir Models for Gas Hydrate Numerical Simulation

Science.gov (United States)

Boswell, R.

2016-12-01

Scientific and industrial drilling programs have now providing detailed information on gas hydrate systems that will increasingly be the subject of field experiments. The need to carefully plan these programs requires reliable prediction of reservoir response to hydrate dissociation. Currently, a major emphasis in gas hydrate modeling is the integration of thermodynamic/hydrologic phenomena with geomechanical response for both reservoir and bounding strata. However, also critical to the ultimate success of these efforts is the appropriate development of input geologic models, including several emerging issues, including (1) reservoir heterogeneity, (2) understanding of the initial petrophysical characteristics of the system (reservoirs and seals), the dynamic evolution of those characteristics during active dissociation, and the interdependency of petrophysical parameters and (3) the nature of reservoir boundaries. Heterogeneity is ubiquitous aspect of every natural reservoir, and appropriate characterization is vital. However, heterogeneity is not random. Vertical variation can be evaluated with core and well log data; however, core data often are challenged by incomplete recovery. Well logs also provide interpretation challenges, particularly where reservoirs are thinly-bedded due to limitation in vertical resolution. This imprecision will extend to any petrophysical measurements that are derived from evaluation of log data. Extrapolation of log data laterally is also complex, and should be supported by geologic mapping. Key petrophysical parameters include porosity, permeability and it many aspects, and water saturation. Field data collected to date suggest that the degree of hydrate saturation is strongly controlled by/dependant upon reservoir quality and that the ratio of free to bound water in the remaining pore space is likely also controlled by reservoir quality. Further, those parameters will also evolve during dissociation, and not necessary in a simple

Methane Hydrates: Chapter 8

Science.gov (United States)

Boswell, Ray; Yamamoto, Koji; Lee, Sung-Rock; Collett, Timothy S.; Kumar, Pushpendra; Dallimore, Scott

2008-01-01

Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Field, laboratory and numerical modelling studies conducted to date indicate that gas can be extracted from gas hydrates with existing production technologies, particularly for those deposits in which the gas hydrate exists as pore-filling grains at high saturation in sand-rich reservoirs. A series of regional resource assessments indicate that substantial volumes of gas hydrate likely exist in sand-rich deposits. Recent field programs in Japan, Canada and in the United States have demonstrated the technical viability of methane extraction from gas-hydrate-bearing sand reservoirs and have investigated a range of potential production scenarios. At present, basic reservoir depressurisation shows the greatest promise and can be conducted using primarily standard industry equipment and procedures. Depressurisation is expected to be the foundation of future production systems; additional processes, such as thermal stimulation, mechanical stimulation and chemical injection, will likely also be integrated as dictated by local geological and other conditions. An innovative carbon dioxide and methane swapping technology is also being studied as a method to produce gas from select gas hydrate deposits. In addition, substantial additional volumes of gas hydrate have been found in dense arrays of grain-displacing veins and nodules in fine-grained, clay-dominated sediments; however, to date, no field tests, and very limited numerical modelling, have been conducted with regard to the production potential of such accumulations. Work remains to further refine: (1) the marine resource volumes within potential accumulations that can be

Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(VOxide as a PEDOT:PSS Replacement

Directory of Open Access Journals (Sweden)

Frederik C. Krebs

2011-01-01

Full Text Available The use of hydrated vanadium(Voxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET and had the structure PET/ITO/ZnO/P3HT:PCBM/V2O5·(H2On/Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(Voxide layers were processed by slot-die coating. The hydrated vanadium(Voxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP. Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(Voxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(Voxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker.

Experimental characterization of thermal and hygric properties of hemp concrete with consideration of the material age evolution

Science.gov (United States)

Bennai, F.; Issaadi, N.; Abahri, K.; Belarbi, R.; Tahakourt, A.

2018-04-01

The incorporation of plant crops in construction materials offers very good hygrothermal performance to the building, ensuring substantial environmental and ecological benefits. This paper focuses on studying the evolution of hygrothermal properties of hemp concrete over age (7, 30 and 60 days). The analysis is done with respect to two main hygric and thermal properties, respectively: sorption isotherms, water vapor permeability, thermal conductivity and heat capacity. In fact, most of these parameters are very susceptible to change function of the age of the material. This influence of the aging is mainly due to the evolution of the microstructure with the binder hydration over time and the creation of new hydrates which can reduces the porosity of the material and consequently modify its properties. All the tested hemp concrete samples presented high moisture storage capacity and high-water vapor permeability whatever the age of such hygroscopic material. These hygric parameters increase significantly for high relative humidity requiring more consideration of such variability during the modeling of coupled heat and mass transfer within the material. By the same, the thermal conductivity and heat capacity tests highlighted the impact of the temperature and hygric state of the studied material.

A Numerical Model for the Thermomechanical Conditions During Hydration of Early-age Concrete

DEFF Research Database (Denmark)

Hattel, Jesper; Thorborg, Jesper

2003-01-01

In the present study, a macroscopic numerical model for the thermomechanical conditions during hydration of early-age concrete is presented. The formulation is based on a semi-coupled, incremental thermomechanical model where the heat production from the hydration process is expressed in terms...... of the maturity and the thermal activation is expressed by the Arrhenius principle. The material properties are assumed to depend on the hydration process via the maturity. The discretization of the governing equations is accomplished by a control volume formulation involving a time-splitting scheme for the heat...

Influence of the cementitious paste composition on the E-modulus and heat of hydration evolutions

International Nuclear Information System (INIS)

Maia, Lino; Azenha, Miguel; Faria, Rui; Figueiras, Joaquim

2011-01-01

E-modulus and heat of hydration are features of cement-based materials that follow a rapid rate of change at early ages. This paper analyses the influence of the composition of cementitious pastes on these features by using two methods: (i) a novel technique for continuously monitoring the E-modulus of cement-based materials, based on evaluating the first resonant frequency of a composite beam containing the material under testing, and (ii) an isothermal calorimeter to determine the released heat of hydration. Seventeen mixes are tested, encompassing pastes with five w/c ratios, as well as different contents of limestone filler, fly ash, silica fume and metakaolin. The results permit the comparison of the E-modulus and heat of hydration sensitivities to mix composition changes, and to check possible relations between these features. This work also helps to establish the technique (i) as a non-destructive method for monitoring the E-modulus evolution in cement-based materials since casting.

In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

Science.gov (United States)

Lee, M.W.; Collett, T.S.

2011-01-01

In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

X-ray and Neutron Diffraction in the Study of Organic Crystalline Hydrates

Directory of Open Access Journals (Sweden)

Katharina Fucke

2010-07-01

Full Text Available A review. Diffraction methods are a powerful tool to investigate the crystal structure of organic compounds in general and their hydrates in particular. The laboratory standard technique of single crystal X-ray diffraction gives information about the molecular conformation, packing and hydrogen bonding in the crystal structure, while powder X-ray diffraction on bulk material can trace hydration/dehydration processes and phase transitions under non-ambient conditions. Neutron diffraction is a valuable complementary technique to X-ray diffraction and gives highly accurate hydrogen atom positions due to the interaction of the radiation with the atomic nuclei. Although not yet often applied to organic hydrates, neutron single crystal and neutron powder diffraction give precise structural data on hydrogen bonding networks which will help explain why hydrates form in the first place.

Development of Alaskan gas hydrate resources: Annual report, October 1986--September 1987

Energy Technology Data Exchange (ETDEWEB)

Sharma, G.D.; Kamath, V.A.; Godbole, S.P.; Patil, S.L.; Paranjpe, S.G.; Mutalik, P.N.; Nadem, N.

1987-10-01

Solid ice-like mixtures of natural gas and water in the form of natural gas hydrated have been found immobilized in the rocks beneath the permafrost in Arctic basins and in muds under the deep water along the American continental margins, in the North Sea and several other locations around the world. It is estimated that the arctic areas of the United States may contain as much as 500 trillion SCF of natural gas in the form of gas hydrates (Lewin and Associates, 1983). While the US Arctic gas hydrate resources may have enormous potential and represent long term future source of natural gas, the recovery of this resource from reservoir frozen with gas hydrates has not been commercialized yet. Continuing study and research is essential to develop technologies which will enable a detailed characterization and assessment of this alternative natural gas resource, so that development of cost effective extraction technology.

Halting of the calcium aluminate cement hydration process

International Nuclear Information System (INIS)

Luz, A.P.; Borba, N.Z; Pandolfelli, V.C.

2011-01-01

The calcium aluminate cement reactions with water lead to the anhydrous phases dissolution resulting a saturated solution, followed by nucleation and crystal growth of the hydrate compounds. This is a dynamic process, therefore, it is necessary to use suitable methods to halt the hydration in order to study the phase transformations kinetics of such materials. In this work two methods are evaluated: use of acetone and microwave drying, aiming to withdraw the free water and inhibit further reactions. X ray diffraction and thermogravimetric tests were used to quantify the phases generated in the cement samples which were kept at 37 deg C for 1 to 15 days. The advantages and disadvantages of those procedures are presented and discussed. The use of microwave to halt the hydration process seems to be effective to withdraw the cement free water, and it can further be used in researches of the refractory castables area, endodontic cements, etc. (author)

Hydration process for calcium-aluminate cement within EVA emulsion by SPring-8 synchrotron radiation x-ray diffraction method

International Nuclear Information System (INIS)

Kotera, Masaru; Matsuda, Ikuyo; Miyashita, Keiko; Adachi, Nobuyuki; Tamura, Hisayuki

2005-01-01

Polymer-modified mortars which consist of a polymer emulsion and cement materials have been widely developed in the construction materials fields. Forming process of the polymer-modified cement membrane simultaneously involves evaporation of water within the polymer emulsion and hydration of cement. It is important for the polymer-modified cement paste that the hydrate crystal of cement is generating by the hydration during the setting process under existence of the polymer emulsion. In this study, hydration process for calcium-aluminate cement under existence of poly (ethylene-vinyl acetate) (EVA) emulsion (polymer-cement ratio=100%) was investigated by X-ray diffraction method using synchrotron radiation (SPring-8). The diffraction peaks of calcium aluminate (CA) disappeared after the hardening, on the other hand, the peaks of hydrate crystals of calcium-aluminate cement (C 2 AH 8 and C 3 AH 6 ) could be observed. This polymer-modified cement paste hydrated using the water within the polymer emulsion. The hydration of C 2 AH 8 from CA started at around 300 min, and then C 3 AH 6 hydrate crystal increased after 700 min at ambient temperature. This implies that the conversion from C 2 AH 8 to C 3 AH 6 occurred to be more stable phase. The setting temperature affected the reaction rate. In case of hydration at 35degC, the start time of the hydration for calcium-aluminate cement was quicker than that in the ambient temperature four or more times. (author)

Novel understanding of calcium silicate hydrate from dilute hydration

KAUST Repository

Zhang, Lina

2017-05-13

The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10 was conducted for tricalcium silicate (C3S) to interpret long-term hydration process and investigate the formation, structure and properties of C-S-H. Based on results from XRD, IR, SEM, NMR and so forth, loose and dense clusters of C-S-H with analogous C/S ratio were obtained along with the corresponding chemical formulae proposed as Ca5Si4O13∙6.2H2O. Crystalline structure inside C-S-H was observed by TEM, which was allocated at the foil-like proportion as well as the edge of wrinkles of the product. The long-term hydration process of C3S in dilute suspension could be sketchily described as migration of calcium hydroxide and in-situ growth of C-S-H with equilibrium silicon in aqueous solution relatively constant and calcium varied.

Formation of submarine gas hydrates

Energy Technology Data Exchange (ETDEWEB)

Soloviev, V.; Ginsburg, G.D. (Reserch Institute of Geology and Mineral Resources of the Ocean ' ' VNII Okeangeologia' ' , St. Petersburg (Russian Federation))

1994-03-01

Submarine gas hydrates have been discoverd in the course of deep-sea drilling (DSDP and ODP) and bottom sampling in many offshore regions. This paper reports on expeditions carried out in the Black, Caspian and Okhotsk Seas. Gas hydrate accumulations were discovered and investigated in all these areas. The data and an analysis of the results of the deep-sea drilling programme suggest that the infiltration of gas-bearing fluids is a necessary condition for gas hydrate accumulation. This is confirmed by geological observations at three scale levels. Firstly, hydrates in cores are usually associated with comparatively coarse-grained, permeable sediments as well as voids and fractures. Secondly, hydrate accumulations are controlled by permeable geological structures, i.e. faults, diapirs, mud volcanos as well as layered sequences. Thirdly, in the worldwide scale, hydrate accumulations are characteristic of continental slopes and rises and intra-continental seas where submarine seepages also are widespread. Both biogenic and catagenic gas may occur, and the gas sources may be located at various distances from the accumulation. Gas hydrates presumably originate from water-dissolved gas. The possibility of a transition from dissolved gas into hydrate is confirmed by experimental data. Shallow gas hydrate accumulations associated with gas-bearing fluid plumes are the most convenient features for the study of submarine hydrate formation in general. These accumulations are known from the Black, Caspian and Okhotsk Seas, the Gulf of Mexico and off northern California. (au) (24 refs.)

Characterizing heterogeneous dynamics at hydrated electrode surfaces

Science.gov (United States)

Willard, Adam P.; Limmer, David T.; Madden, Paul A.; Chandler, David

2013-05-01

In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the first hydration layer are spatially and temporally correlated. To interpret these collective motions, we apply quantitative measures of dynamic heterogeneity that are standard tools for considering glassy systems. Specifically, we carry out an analysis in terms of mobility fields and distributions of persistence times and exchange times. In so doing, we show that dynamics in these systems is facilitated by transient disorder in frustrated two-dimensional hydrogen bonding networks. The frustration is the result of unfavorable geometry imposed by strong metal-water bonding. The geometry depends upon the structure of the underlying metal surface. Dynamic heterogeneity of water on the Pt 111 surface is therefore qualitatively different than that for water on the Pt 100 surface. In both cases, statistics of this ad-layer dynamic heterogeneity responds asymmetrically to applied voltage.

Characterizing heterogeneous dynamics at hydrated electrode surfaces.

Science.gov (United States)

Willard, Adam P; Limmer, David T; Madden, Paul A; Chandler, David

2013-05-14

In models of Pt 111 and Pt 100 surfaces in water, motions of molecules in the first hydration layer are spatially and temporally correlated. To interpret these collective motions, we apply quantitative measures of dynamic heterogeneity that are standard tools for considering glassy systems. Specifically, we carry out an analysis in terms of mobility fields and distributions of persistence times and exchange times. In so doing, we show that dynamics in these systems is facilitated by transient disorder in frustrated two-dimensional hydrogen bonding networks. The frustration is the result of unfavorable geometry imposed by strong metal-water bonding. The geometry depends upon the structure of the underlying metal surface. Dynamic heterogeneity of water on the Pt 111 surface is therefore qualitatively different than that for water on the Pt 100 surface. In both cases, statistics of this ad-layer dynamic heterogeneity responds asymmetrically to applied voltage.

Crystallographic characterization of cement pastes hydrated with NaCl; Caracterizacao cristalografica de pastas de cimento hidratadas com NaCl

Energy Technology Data Exchange (ETDEWEB)

Melo, Carina Gabriela de Melo e; Martinelli, Antonio Eduardo; Melo, Dulce Maria Araujo; Melo, Marcus Antonio de Freitas; Melo, Vitor Rodrigo de Melo e [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

2012-07-01

One of the major current challenges faced by oil companies is the exploration of pre salt basins. Salt layers deposited upon the evaporation of ocean water and continental separation are mainly formed by NaCl and isolate immense oil reservoirs. The mechanical stability and zonal isolation of oil wells that run through salt layers must be fulfilled by cement sheaths saturated with NaCl to assure chemical compatibility between cement and salt layer. The present study aimed at evaluating the effect of NaCl addition on the hydration of oil well cement slurries as well as identifying the nature of crystalline phases present in the hardened cement. To that end, cement slurries containing NaCl were mixed, hardened and characterized by X-ray diffraction. The results revealed that the presence of NaCl affects the formation of hydration products by the presence of Friedel's salt. The intensity of the corresponding peaks increase as the contents of NaCl in the slurry increase. High concentrations of NaCl in Portland slurries increase the setting time of cement and the presence of Friedel's salt decreases the strength of the hardened cement. (author)

In Situ Soft X-ray Spectromicroscopy of Early Tricalcium Silicate Hydration

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Sungchul Bae

2016-12-01

Full Text Available The understanding and control of early hydration of tricalcium silicate (C3S is of great importance to cement science and concrete technology. However, traditional characterization methods are incapable of providing morphological and spectroscopic information about in situ hydration at the nanoscale. Using soft X-ray spectromicroscopy, we report the changes in morphology and molecular structure of C3S at an early stage of hydration. In situ C3S hydration in a wet cell, beginning with induction (~1 h and acceleration (~4 h periods of up to ~8 h, was studied and compared with ex situ measurements in the deceleration period after 15 h of curing. Analysis of the near-edge X-ray absorption fine structure showed that the Ca binding energy and energy splitting of C3S changed rapidly in the early age of hydration and exhibited values similar to calcium silicate hydrate (C–S–H. The formation of C–S–H nanoseeds in the C3S solution and the development of a fibrillar C–S–H morphology on the C3S surface were visualized. Following this, silicate polymerization accompanied by C–S–H precipitation produced chemical shifts in the peaks of the main Si K edge and in multiple scattering. However, the silicate polymerization process did not significantly affect the Ca binding energy of C–S–H.

Deep-Subsurface Marine Methane Hydrate Microbial Communities: Who's There and What Are They Doing?

Science.gov (United States)

Colwell, F.; Reed, D.; Fujita, Y.; Delwiche, M.; Blackwelder, D.; Uchida, T.; Fujii, T.; Lu, H.

2001-12-01

Natural gas hydrates are crystalline deposits of freshwater and primarily methane. They are estimated to represent a potentially vast reservoir of energy. Relatively little is known regarding microbial communities surrounding deep [>100 meters below sea floor (mbsf)] hydrate-bearing sediments. Deep sediment cores were collected in zones above, within, and below the hydrate bearing strata in an accretionary prism off the coast of Japan. Microorganisms were characterized using cultivation- and non-cultivation-based microbiological techniques to better understand the role that they play in the production and distribution of methane in gas hydrates. Direct counts show cell density at 105 cells/g throughout the hydrate strata. Lipid and 16S rDNA analyses indicate that diverse bacterial and archaeal microorganisms are represented throughout the strata. Acetate and hydrogen were utilized as an energy source for methane-producing microorganisms from each sediment depth. Although the methanogenic biomarker coenzyme M was not present above the detection limit in any of the samples, cloning and characterization of amplified 16S ribosomal RNA genes indicated the presence of methanogenic microorganisms related to the Methanobacteriales and Methanococcales. In addition, archaeal clones closely related to the hyperthermophilic Pyrodictiales were detected. Analysis of eubacterial clones indicated a more diverse eubacterial community compared to the archaea, including members from the groups of cyanobacteria, proteobacteria, gram positive bacteria, and flexibacter-cytophaga-bacteriodes. This study suggests that the diversity of microbial communities associated with the presence of methane in gas hydrate-rich deep marine sediments is greater than previously estimated.

A spectroscopic study of the structure and occupancies of clathrate hydrates incorporating hydrogen

Science.gov (United States)

Grim, R. Gary

With the ability to store and concentrate gases inside a clean and abundant water framework, clathrate hydrates are considered to be a promising material for many applications related to gas storage, separation, and sequestration. Hydrates of hydrogen are particularly interesting, for in addition to these potential applications, the small molecular size provides an opportunity for use as a model guest in many fundamental studies such as guest diffusion, multiple guest occupancy, and quantum mechanical effects upon confinement. In attempt to study these effects and the viability of H 2 hydrates as an energy storage material, a combined experimental and theoretical approach incorporating Raman spectroscopy, X-ray and neutron diffraction, nuclear magnetic resonance, ab-initio calculations, and molecular dynamic simulations was performed. One of the most significant challenges in the application of H2 clathrate hydrates is the demanding thermodynamic requirements needed for stability. In recent years, a mechanism known as the `tuning' effect had reportedly solved this issue where thermodynamic requirements could be reduced while simultaneously maintaining high storage capacities. In this work, the viability and validity of this technique is explored and alternative explanations in the form of epitaxial hydrate growth under high driving force conditions are discussed. A second, and equally important challenge facing clathrate hydrates as a future storage material is the overall storage capacity of H2. In previous work, H2 has only been experimentally verified to occupy the small 512 and 43566 3 cages and also in the large 51264 cages of the type II clathrate, often with an energy deficient promoter. In order to achieve more robust energy densities, other hydrate cages must be accessible. Herein a new method for increasing overall hydrate energy densities is presented involving the incorporation of H2 in the large cages of the type I clathrate with CH4 as a co

Characterization of dielectric materials

Energy Technology Data Exchange (ETDEWEB)

King, Danny J.; Babinec, Susan; Hagans, Patrick L.; Maxey, Lonnie C.; Payzant, Edward A.; Daniel, Claus; Sabau, Adrian S.; Dinwiddie, Ralph B.; Armstrong, Beth L.; Howe, Jane Y.; Wood, III, David L.; Nembhard, Nicole S.

2017-06-27

A system and a method for characterizing a dielectric material are provided. The system and method generally include applying an excitation signal to electrodes on opposing sides of the dielectric material to evaluate a property of the dielectric material. The method can further include measuring the capacitive impedance across the dielectric material, and determining a variation in the capacitive impedance with respect to either or both of a time domain and a frequency domain. The measured property can include pore size and surface imperfections. The method can still further include modifying a processing parameter as the dielectric material is formed in response to the detected variations in the capacitive impedance, which can correspond to a non-uniformity in the dielectric material.

Critical guest concentration and complete tuning pattern appearing in the binary clathrate hydrates

Energy Technology Data Exchange (ETDEWEB)

Cha, J.H.; Lee, H. [Korea Advanced Inst. of Science and Technology, Yuseong-gu, Daejeon (Korea, Republic of). Dept. of Chemical and Biomolecular Engineering; Kim, D.Y. [SK Engineering and Construction, Jongno-gu, Seoul (Korea, Republic of); Park, J. [Hanwha Chemical R and D Center, Yuseong-gu, Daejeon (Korea, Republic of); Lee, J.W. [Kongju National Univ., Cheonan, Chungnam (Korea, Republic of); Ripmeester, J.A. [National Research Council of Canada, Ottawa, ON (Canada). Steacie Inst. for Molecular Sciences

2008-07-01

Clathrate hydrates, or gas hydrates, are stabilized by van der Waals interaction between a guest molecule and a host framework. Because of their property, they are a potential resource in the exploitation of natural gas hydrates, as a material for the sequestration of carbon dioxide (CO{sub 2}), as a means of storage and transportation of natural gas, as well as hydrogen storage. Clathrate hydrate research can be divided into two categories that emphasize either macroscopic or microscopic approaches. However, these two approaches need to be closely linked for a better understanding of the structures and processes involving both natural phenomena and hydrates for industrial processes. Details on the molecular scale that concern the less usual properties of clathrate hydrates remain unknown. This paper presented the results of a study that reported on the existence of a critical guest concentration (CGC) and established the complete tuning pattern that occurred in the binary hydrates, including water-soluble hydrate formers (promoters) and water-insoluble guests. The paper presented the experimental procedures, including formation of the methane (CH{sub 4}) and tetrahydrofuran (THF) binary hydrate; a schematic diagram of the experimental apparatus; and formation of the CH{sub 4} and t-BuNH{sub 2} binary hydrate. Nuclear magnetic resonance (NMR) spectroscopic measurements and thermodynamic measurements were also presented. It was concluded that the CGC value appeared to primarily depend on the chemical nature of a liquid guest component participating in the binary hydrate formation. 10 refs., 2 tabs., 9 figs.

Formation and Transformation Behavior of Sodium Dehydroacetate Hydrates

Directory of Open Access Journals (Sweden)

Xia Zhang

2016-04-01

Full Text Available The effect of various controlling factors on the polymorphic outcome of sodium dehydroacetate crystallization was investigated in this study. Cooling crystallization experiments of sodium dehydroacetate in water were conducted at different concentrations. The results revealed that the rate of supersaturation generation played a key role in the formation of the hydrates. At a high supersaturation generation rate, a new sodium dehydroacetate dihydrate needle form was obtained; on the contrary, a sodium dehydroacetate plate monohydrate was formed at a low supersaturation generation rate. Furthermore, the characterization and transformation behavior of these two hydrated forms were investigated with the combined use of microscopy, powder X-ray diffraction (PXRD, Raman spectroscopy, Fourier transform infrared (FTIR, thermal gravimetric analysis (TGA, scanning electron microscopy (SEM and dynamic vapor sorption (DVS. It was found that the new needle crystals were dihydrated and hollow, and they eventually transformed into sodium dehydroacetate monohydrate. In addition, the mechanism of formation of sodium dehydroacetate hydrates was discussed, and a process growth model of hollow crystals in cooling crystallization was proposed.

Dynamic impact indentation of hydrated biological tissues and tissue surrogate gels

Science.gov (United States)

Ilke Kalcioglu, Z.; Qu, Meng; Strawhecker, Kenneth E.; Shazly, Tarek; Edelman, Elazer; VanLandingham, Mark R.; Smith, James F.; Van Vliet, Krystyn J.

2011-03-01

For both materials engineering research and applied biomedicine, a growing need exists to quantify mechanical behaviour of tissues under defined hydration and loading conditions. In particular, characterisation under dynamic contact-loading conditions can enable quantitative predictions of deformation due to high rate 'impact' events typical of industrial accidents and ballistic insults. The impact indentation responses were examined of both hydrated tissues and candidate tissue surrogate materials. The goals of this work were to determine the mechanical response of fully hydrated soft tissues under defined dynamic loading conditions, and to identify design principles by which synthetic, air-stable polymers could mimic those responses. Soft tissues from two organs (liver and heart), a commercially available tissue surrogate gel (Perma-Gel™) and three styrenic block copolymer gels were investigated. Impact indentation enabled quantification of resistance to penetration and energy dissipative constants under the rates and energy densities of interest for tissue surrogate applications. These analyses indicated that the energy dissipation capacity under dynamic impact increased with increasing diblock concentration in the styrenic gels. Under the impact rates employed (2 mm/s to 20 mm/s, corresponding to approximate strain energy densities from 0.4 kJ/m3 to 20 kJ/m3), the energy dissipation capacities of fully hydrated soft tissues were ultimately well matched by a 50/50 triblock/diblock composition that is stable in ambient environments. More generally, the methodologies detailed here facilitate further optimisation of impact energy dissipation capacity of polymer-based tissue surrogate materials, either in air or in fluids.

Physical properties of sediments from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well

Science.gov (United States)

Winters, W.J.

1999-01-01

A 1150 m deep gas hydrate research well was drilled in the Canadian Arctic in February and March 1998 to investigate the interaction between the presence of gas hydrate and the natural conditions presented by the host sediments. Profiles of the following measured and derived properties are presented from that investigation: water content, sediment wet bulk density, grain size, porosity, gas hydrate quantity, and salinity. These data indicate that the greatest concentration of gas hydrate is located within sand and gravel deposits between 897 m and 922 m. American Society for Testing and Materials 1997: Standard test method for specific gravity of soil solids by gas pycnometer D 5550-94; in American Society for Testing and Materials, Annual Book of ASTM Standards, v. 04.09, Soil and Rock, West Conshohocken, Pennsylvania, p. 380-383.

Hydro-bio-geomechanical properties of hydrate-bearing sediments from Nankai Trough

Science.gov (United States)

Santamarina, J.C.; Dai, Shifeng; Terzariol, M.; Jang, Jeonghwan; Waite, William F.; Winters, William J.; Nagao, J.; Yoneda, J.; Konno, Y.; Fujii, T.; Suzuki, K.

2015-01-01

Natural hydrate-bearing sediments from the Nankai Trough, offshore Japan, were studied using the Pressure Core Characterization Tools (PCCTs) to obtain geomechanical, hydrological, electrical, and biological properties under in situ pressure, temperature, and restored effective stress conditions. Measurement results, combined with index-property data and analytical physics-based models, provide unique insight into hydrate-bearing sediments in situ. Tested cores contain some silty-sands, but are predominantly sandy- and clayey-silts. Hydrate saturations Sh range from 0.15 to 0.74, with significant concentrations in the silty-sands. Wave velocity and flexible-wall permeameter measurements on never-depressurized pressure-core sediments suggest hydrates in the coarser-grained zones, the silty-sands where Sh exceeds 0.4, contribute to soil-skeletal stability and are load-bearing. In the sandy- and clayey-silts, where Sh < 0.4, the state of effective stress and stress history are significant factors determining sediment stiffness. Controlled depressurization tests show that hydrate dissociation occurs too quickly to maintain thermodynamic equilibrium, and pressure–temperature conditions track the hydrate stability boundary in pure-water, rather than that in seawater, in spite of both the in situ pore water and the water used to maintain specimen pore pressure prior to dissociation being saline. Hydrate dissociation accompanied with fines migration caused up to 2.4% vertical strain contraction. The first-ever direct shear measurements on never-depressurized pressure-core specimens show hydrate-bearing sediments have higher sediment strength and peak friction angle than post-dissociation sediments, but the residual friction angle remains the same in both cases. Permeability measurements made before and after hydrate dissociation demonstrate that water permeability increases after dissociation, but the gain is limited by the transition from hydrate saturation

Methods to determine hydration states of minerals and cement hydrates

Energy Technology Data Exchange (ETDEWEB)

Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

2014-11-15

This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement hydrates in different hydration states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of hydrated phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in hydrated cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na{sub 2}SO{sub 4}–H{sub 2}O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions.

Methods to determine hydration states of minerals and cement hydrates

International Nuclear Information System (INIS)

Baquerizo, Luis G.; Matschei, Thomas; Scrivener, Karen L.; Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars

2014-01-01

This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement hydrates in different hydration states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of hydrated phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in hydrated cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na 2 SO 4 –H 2 O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions

Enthalpy of dissociation and hydration number of methane hydrate from the Clapeyron equation

International Nuclear Information System (INIS)

Anderson, Graydon K.

2004-01-01

The enthalpies of the reactions in which methane hydrate is dissociated to methane vapor and either (1) water, or (2) ice are determined by a new analysis using the Clapeyron equation. The difference in enthalpies of the two reactions is used to infer the hydration number at the quadruple point where hydrate, ice, liquid water, and methane vapor coexist. By appropriate corrections, the hydration number at points removed from the quadruple point is also determined. The most important feature of the new analysis is the direct use of the Clapeyron equation. The method avoids the use of certain simplifying assumptions that have compromised the accuracy of previous analyses in which the Clausius-Clapeyron equation was used. The analysis takes into account the finite volumes of all phases, the non-ideality of the vapor phase, and the solubility of methane in water. The results show that the enthalpy of dissociation and hydration number are constant within experimental error over the entire (hydrate, liquid, vapor) coexistence region. The results are more accurate than but entirely consistent with almost all previous studies

Relation of submarine landslide to hydrate occurrences in Baiyun Depression, South China Sea

Science.gov (United States)

Sun, Yunbao; Zhang, Xiaohua; Wu, Shiguo; Wang, Lei; Yang, Shengxiong

2018-02-01

Submarine landslides have been observed in the Baiyun Depression of the South China Sea. The occurrence of hydrates below these landslides indicates that these slope instabilities may be closely related to the massive release of methane. In this study, we used a simple Monte-Carlo model to determine the first-order deformation pattern of a gravitationally destabilizing slope. The results show that a stress concentration occurs due to hydrate dissociation on the nearby glide surface and on top of a gas chimney structure. Upon the dissolution of the gas hydrate, slope failure occurs due to the excess pore pressure generated by the dissociation of the gas hydrates. When gas hydrates dissociate at shallow depths, the excess pore pressure generated can be greater than the total stress acting at those points, along with the forces that resist sliding. Initially, the failure occurs at the toe of the slope, then extends to the interior. Although our investigation focused only on the contribution of hydrate decomposition to submarine landslide, this process is also affected by both the slope material properties and topography.

Fire extinction utilizing carbon dioxide hydrate

Energy Technology Data Exchange (ETDEWEB)

Hatakeyama, T.; Aida, E.; Yokomori, T.; Ohmura, R.; Ueda, T. [Keio Univ., Hiyoshi, Kohoku-ku, Yokohama (Japan)

2008-07-01

Clathrate hydrates formed with nonflammable gases may be suitable for use as fire extinguishing agents because dissociation of the hydrates results in the temperature decrease in the combustion field and the nonflammable gases released from the dissociated hydrates prevent the supply of the oxygen to the combustion field. This paper discussed experiments in which ordinary ice and dry ice were used to evaluate the performance of CO{sub 2} hydrate as a fire extinguishing agent. The paper described the apparatus and procedure for the preparation of CO{sub 2} hydrate crystals. A schematic of the reactor to form CO{sub 2} hydrate and a photograph of CO{sub 2} hydrate crystal formed in the study were also presented. Other illustrations, photographs, and tables that were presented included a schematic diagram of the experimental apparatus used for the flame extinction experiments; a photograph of CO{sub 2} hydrate powder; sequential video graphs of the flame extinction by the supply of CO{sub 2} hydrate crystals to the methanol pool flame and the relevant illustration; and heat of CO{sub 2} hydrate dissociation, water vaporization and sublimation of dry ice. It was concluded that the critical mass of the CO{sub 2} hydrate required to extinguish a flame was much less than that of ordinary ice, indicating the superiority of CO{sub 2} hydrate to the ice. In addition, the experiments also revealed that the size of the CO{sub 2} hydrate particles had a significant effect on the performance of flame extinction. 5 refs., 2 tabs., 7 figs.

Hydrates on tap: scientists say natural gas hydrates may be tough nut to crack

Energy Technology Data Exchange (ETDEWEB)

Mahoney, J.

2001-12-01

Gas hydrates are methane molecules trapped in cages of water molecules, yielding a substance with a slushy, sherbet-like consistency. Drilling for hydrates is similar to conventional oil and gas drilling, however, the secret to economic production still remains hidden. Hydrates exist in abundance in such places as deep ocean floor and below ground in some polar regions. The real challenge lies in producing gas from this resource, inasmuch as there is no existing technology for production of gas specifically from methane hydrates. This paper describes an international research program, involving a five-country partnership to spud the first of three wells into the permafrost of the Mackenzie River Delta in the Northwest Territories. The project, worth about $15 million, has brought together public funding and expertise from Japan, Germany, India as well as the Canadian and US Geological Surveys and the US Dept. of Energy in an effort to gain information on the production response of gas hydrates. The operator of the project is Japan Petroleum Exploration Company of Canada, a subsidiary of Japan National Oil Corporation. Since Japan is poor in domestic hydrocarbon resources, but is surrounded by deep water that contains potential for gas hydrates, Japan has a great deal riding on the success of this project. Germany and the United States are also very much interested. Current thinking is that gas is in contact with the hydrates and that it should be possible to develop a free gas reservoir as if it were a conventional deposit. As the free gas is drawn off, the pressure is reduced on the hydrates in contact with it , the hydrates dissociate from the gas and replenish the conventional reservoir. So far this is still only a theory, but it appears to be a sensible approach to hydrate production. 1 photo.

Characterization of plutonium-containing materials and storage canisters

International Nuclear Information System (INIS)

Mason, R.E.

1997-01-01

Throughout the weapons complex, plutonium materials are stored in various containers. Some plutonium has been stored for 20 yr or more. The physical and chemical properties of the plutonium material and the containers that hold it are often not well characterized. The U.S. Department of Energy (DOE) 3013 standard sets criteria to which stored material must conform. The 3013 standard regulates materials that hold 50% or greater plutonium, and the other 50% is not specified and is usually unknown. The Materials Identification and Surveillance project is tasked to characterize representative materials and begin to characterize the other 50% and to show that materials can be brought into 3013 criteria conformance through thermal treatments

Analysis of vaginal microbicide film hydration kinetics by quantitative imaging refractometry.

Directory of Open Access Journals (Sweden)

Matthew Rinehart

Full Text Available We have developed a quantitative imaging refractometry technique, based on holographic phase microscopy, as a tool for investigating microscopic structural changes in water-soluble polymeric materials. Here we apply the approach to analyze the structural degradation of vaginal topical microbicide films due to water uptake. We implemented transmission imaging of 1-mm diameter film samples loaded into a flow chamber with a 1.5×2 mm field of view. After water was flooded into the chamber, interference images were captured and analyzed to obtain high resolution maps of the local refractive index and subsequently the volume fraction and mass density of film material at each spatial location. Here, we compare the hydration dynamics of a panel of films with varying thicknesses and polymer compositions, demonstrating that quantitative imaging refractometry can be an effective tool for evaluating and characterizing the performance of candidate microbicide film designs for anti-HIV drug delivery.

Waters of Hydration of Cupric Hydrates: A Comparison between Heating and Absorbance Methods

Science.gov (United States)

Barlag, Rebecca; Nyasulu, Frazier

2011-01-01

The empirical formulas of four cupric hydrates are determined by measuring the absorbance in aqueous solution. The Beer-Lambert Law is verified by constructing a calibration curve of absorbance versus known Cu[superscript 2+](aq) concentration. A solution of the unknown hydrate is prepared by using 0.2-0.3 g of hydrate, and water is added such…

Speed and Strain of Polypyrrole Actuators: Dependence on Cation Hydration Number

DEFF Research Database (Denmark)

Jafeen, Mohamed J.M.; Careem, Mohamed A.; Skaarup, Steen

2010-01-01

Polypyrrole films have been characterized by simultaneous cyclic voltammetry driven force-displacement measurements. The aim was to clarify the role of cations in the electrolyte on the speed of response and on the strain of the film. The strain as a function of actuation frequency was studied in...... frequencies, the strain depends almost exclusively on insertion of strongly solvated cations and therefore depends on the hydration number of the cations: Li+ (hydration number ~5.4) gives more strain than Na+ (~4.4) and much more than Cs+ (~0) as predicted by the model....

Roll-to-Roll Processing of Inverted Polymer Solar Cells using Hydrated Vanadium(V)Oxide as a PEDOT:PSS Replacement.

Science.gov (United States)

Espinosa, Nieves; Dam, Henrik Friis; Tanenbaum, David M; Andreasen, Jens W; Jørgensen, Mikkel; Krebs, Frederik C

2011-01-11

The use of hydrated vanadium(V)oxide as a replacement of the commonly employed hole transporting material PEDOT:PSS was explored in this work. Polymer solar cells were prepared by spin coating on glass. Polymer solar cells and modules comprising 16 serially connected cells were prepared using full roll-to-roll (R2R) processing of all layers. The devices were prepared on flexible polyethyleneterphthalate (PET) and had the structure PET/ITO/ZnO/P3HT:PCBM/V₂O₅·(H₂O) n /Ag. The ITO and silver electrodes were processed and patterned by use of screen printing. The zinc oxide, P3HT:PCBM and vanadium(V)oxide layers were processed by slot-die coating. The hydrated vanadium(V)oxide layer was slot-die coated using an isopropanol solution of vanadyl-triisopropoxide (VTIP). Coating experiments were carried out to establish the critical thickness of the hydrated vanadium(V)oxide layer by varying the concentration of the VTIP precursor over two orders of magnitude. Hydrated vanadium(V)oxide layers were characterized by profilometry, scanning electron microscopy, energy dispersive X-ray spectroscopy, and grazing incidence wide angle X-ray scattering. The power conversion efficiency (PCE) for completed modules was up to 0.18%, in contrast to single cells where efficiencies of 0.4% were achieved. Stability tests under indoor and outdoor conditions were accomplished over three weeks on a solar tracker.

Methane hydrate dissociation using inverted five-spot water flooding method in cubic hydrate simulator

International Nuclear Information System (INIS)

Li, Gang; Li, Xiao-Sen; Li, Bo; Wang, Yi

2014-01-01

The combination forms of the hydrate dissociation methods in different well systems are divided into 6 main patterns. Dissociation processes of methane hydrate in porous media using the inverted five-spot water flooding method (Pattern 4) are investigated by the experimental observation and numerical simulation. In situ methane hydrate is synthesized in the Cubic Hydrate Simulator (CHS), a 5.832-L cubic reactor. A center vertical well is used as the hot water injection well, while the four vertical wells at the corner are the gas and water production wells. The gas production begins simultaneously with the hot water injection, while after approximately 20 min of compression, the water begins to be produced. One of the common characteristics of the inverted five-spot water flooding method is that both the gas and water production rates decrease with the reduction of the hydrate dissociation rate. The evaluation of the energy efficiency ratio might indicate the inverted five-spot water flooding as a promising gas producing method from the hydrate reservoir. - Highlights: • A three-dimensional 5.8-L cubic pressure vessel is developed. • Gas production of hydrate using inverted five-spot flooding method is studied. • Water/gas production rate and energy efficiency ratio are evaluated. • Temperature distributions of numerical simulation and experiment agree well. • Hydrate dissociation process is a moving boundary problem in this study

Applications of solid-state Nuclear Magnetic Resonance (NMR) in studies of Portland cements-based materials

DEFF Research Database (Denmark)

Skibsted, Jørgen; Andersen, Morten Daugaard; Jakobsen, Hans Jørgen

2007-01-01

Solid-state NMR spectroscopy represents an important research tool in the characterization of a range of structural properties for cement-based materials. Different approaches of the technique can be used to obtain information on hydration kinetics, mobile and bound water, porosity, and local...... atomic structures. After a short introduction to these NMR techniques, it is exemplified how magic-angle spinning (MAS) NMR can provide quantitative and structural information about specific phases in anhydrous and hydrated Portland cements with main emphasis on the incorporation of Al3+ ions...

Formation rate of natural gas hydrate

Energy Technology Data Exchange (ETDEWEB)

Mork, Marit

2002-07-01

The rate of methane hydrate and natural gas hydrate formation was measured in a 9.5 litre stirred tank reactor of standard design. The experiments were performed to better understand the performance and scale-up of a reactor for continuous production of natural gas hydrates. The hydrate formation rate was measured at steady-state conditions at pressures between 70 and 90 bar and temperatures between 7 and 15 deg C. Between 44 and 56 % of the gas continuously supplied to the reactor was converted to hydrate. The experimental results show that the rate of hydrate formation is strongly influenced by gas injection rate and pressure. The effect of stirring rate is less significant and subcooling has no observable effect on the formation rate. Hydrate crystal concentration and gas composition do not influence the hydrate formation rate. Observations of produced hydrate crystals indicate that the crystals are elongated, about 5 micron in diameter and 10 micron long. Analysis of the results shows that the rate of hydrate formation is dominated by gas-liquid mass transfer. A mass transfer model, the bubble-to-crystal model, was developed for the hydrate formation rate in a continuous stirred tank reactor, given in terms of concentration driving force and an overall mass transfer coefficient. The driving force is the difference between the gas concentration at the gas-liquid interface and at the hydrate crystal surface. These concentrations correspond to the solubility of gas in water at experimental temperature and pressure and the solubility of gas at hydrate equilibrium temperature and experimental pressure, respectively. The overall mass transfer coefficient is expressed in terms of superficial gas velocity and impeller power consumption, parameters commonly used in study of stirred tank reactors. Experiments and modeling show that the stirred tank reactor has a considerable potential for increased production capacity. However, at higher hydrate production rates the

The CO{sub 2} hydrate slurry; Le coulis de glace

Energy Technology Data Exchange (ETDEWEB)

Sari, O.; Hu, J.; Eicher, S.; Brun, F. [Institute of Thermal Engineering, University of Applied Sciences of Western Switzerland, Yverdon-les-Bains (Switzerland); Sari, O.; Hu, J. [Clean Cooling Solutions, spin off of University of Applied Sciences of Western Switzerland, Yverdon-les-Bains (Switzerland); Homsy, P. [Nestec Ltd, Vevey (Switzerland); Logel, J.-C. [Axima Refrigeration, Bischheim (France)

2007-12-15

A new, very promising refrigerant was developed, which could be used in industrial processes as well as air conditioners: the CO{sub 2} hydrate slurry. Replacing hydrochlorofluorocarbon HCFC refrigerants has a high priority, due to the strong negative environmental impact of these fluids. New refrigerants have to be environment friendly, non-inflammable, cheap and made of natural materials. CO{sub 2} hydrate slurries and/or a mixture of ice slurry and CO{sub 2} hydrate slurry meet these requirements. The University of Applied Sciences of Western Switzerland in Yverdon, together with industrial partners, investigated the properties of such slurries. The slurries were created using the Coldeco process: the refrigerating fluid is directly injected into the liquid brine. The evaporation of the refrigerating fluid cools the liquid down to its freezing point and homogeneously distributed small crystals appear in the liquid. A test rig was built to measure the physical and chemical properties of the slurries obtained in this way. CO{sub 2} hydrate slurries have a higher energy storage capacitance (500 kJ/kg) than ice slurries (333 kJ/kg). The production of CO{sub 2} hydrate slurries in large quantities in a continuous process was demonstrated. The solid particle concentration was 10%, the pressure amounted to 30 bar and the temperature 2 to 4 {sup o}C. Such slurries can be pumped and circulated in pipe networks. Stainless steel is the appropriate material for such networks. However, the main advantage of the new refrigerant will be, according to the authors, a reduced energy consumption compared to traditional refrigerating cycles: the difference between the temperature required by the user and the refrigerant temperature is reduced, thanks to the use of the latent heat in the new process.

Flow assurance intervention, hydrates remediation

Energy Technology Data Exchange (ETDEWEB)

Mancini, Christopher S. [Oceaneering International Inc., Houston, TX (United States)

2012-07-01

This paper addresses the issues of removing hydrates in sub sea flow lines and associated equipment with an Remotely Operated Vehicle (ROV) of opportunity and a multi-service-vessel (MSV). The paper is split into three topics: the equipment used with the ROV, assessing the interface points and handling fluids produced from drawing down the pressure. Each section is explained thoroughly and backed up with real world experience. The equipment section details information from actual jobs performed and why the particular components were utilized. The system is generally contained in an ROV mounted skid. Pumps are utilized to draw down the pressure inside the hydrated section of equipment, removing one of the three necessary components for hydrates formation. Once the section is pumped down, several options exist for handling the fluids pumped out of the system: pumping to surface, re-injection into the well, or injection into an operating flow line. This method of hydrates remediation is both economical and timely. Hydrate blockages form in low temperatures and high pressures. Reducing the pressure or increasing the temperature so the conditions lie to the right of the hydrate dissociation curve will slowly decompose the blockage. Depressurization and the use of MEG or methanol will give favorable conditions to remove the hydrate plug. Oceaneering has the capabilities to remove hydrates using the FRS in conjunction with an installation vessel to dispose of the gas and fluid removed from the flow line. Hydrate remediation techniques should be implemented into the initial design to reduce costs later. The cost of stopped production combined with the day rate for equipment needed for hydrate removal outweighs the costs if no technique is utilized. (author)

Stress and gas hydrate-filled fracture distribution, Krishna-Godavari Basin, India

Energy Technology Data Exchange (ETDEWEB)

Cook, A.; Goldberg, D. [Lamont-Doherty Earth Observatory of Columbia Univ., Palisades, NY (United States)

2008-07-01

The first expedition of the Indian National Gas Hydrate Program (NGHP) was launched in the summer of 2006 to characterize the presence of gas hydrates on the continental margins of India. This paper presented a study from the NGHP expedition that found high resistivity fractures in unconsolidated clay sediments on logging-while-drilling (LWD) borehole resistivity images. Gas hydrate-filled and conductive fractures appearing on LWD resistivity images in holes 5A, 5B, 6A, 7A and 10 were analysed and discussed. Fracture orientation and shallow sediment stress orientations were determined for each hole. The paper described how to determine which sections of a log are hydrate bearing as well as how to calculate the predicted water saturated resistivity. It was concluded that holes 5A, 5B, 6A and 7A contained well-ordered, high-angle fractures, from which horizontal stress directions could be accurately resolved. However, these stress directions, contradicted the orientations normally seen on a passive margin, and may be the result of local bathymetry variations. 6 refs., 1 tab., 11 figs.

Modelling porewater chemistry in hydrated Portland cement

International Nuclear Information System (INIS)

Berner, U.R.

1987-01-01

Extensive employment of concrete is foreseen in radioactive waste repositories. A prerequisite for modelling the interactions between concrete and formation waters is characterization of the concrete system. Available experimental data from high pressure squeezing of cement pore-water indicate that, besides the high pH due to alkali hydroxide dissolution, cement composition itself influences the solubility determining solid phases. A model which simulates the hydration of Portland cement assuming complete hydration of the main clinker minerals is presented. The model also includes parameters describing the reactions between the cement and blending agents. Comparison with measured pore-water data generally gives a consistent picture and, as expected, the model gives correct predictions for pure Portland cements. For blended cements, the required additional parameters can, to some extent, be derived from pore-water analysis. 14 references, 1 figure, 4 tables

Activation of Ca(OH){sub 2} using different siliceous materials

Energy Technology Data Exchange (ETDEWEB)

Karatepe, N.; Ersoy-Mericboyu, A.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey)

1999-04-01

Siliceous materials such as silica fume, bentonite and diatomite were mixed with Ca(OH){sub 2} and hydrated at different conditions to produce reactive SO{sub 2} sorbents. Two different hydration methods were used, namely atmospheric and pressure hydration. The effects of the hydration temperature, time and siliceous material/Ca(OH){sub 2} weight ratio on the physical properties of the activated sorbents wereinvestigated. A statistical design technique was applied by use of a two-level factorial design matrix to interpret experimental results. In atmospheric hydration, it was found that increasing the temperature and hydration time caused an increase in the total surface area of the sorbents. But, increasing the siliceous material/Ca(OH){sub 2} weight ratio caused a decrease in the total surface area of the sorbents. In pressure hydration, mathematical analysis showed that the surface area of the activated sorbents was positively affected by the hydration variables. Thermogravimetric measurements showed that increasing the amount of reacted Ca(OH){sub 2} during hydration caused an increase in the surface area of the sorbent. X-ray diffraction studies also indicated that calcium silicate hydrates were the principal Ca-containing species formed during hydration.

Hydration sites of unpaired RNA bases: a statistical analysis of the PDB structures

Directory of Open Access Journals (Sweden)

Carugo Oliviero

2011-10-01

Full Text Available Abstract Background Hydration is crucial for RNA structure and function. X-ray crystallography is the most commonly used method to determine RNA structures and hydration and, therefore, statistical surveys are based on crystallographic results, the number of which is quickly increasing. Results A statistical analysis of the water molecule distribution in high-resolution X-ray structures of unpaired RNA nucleotides showed that: different bases have the same penchant to be surrounded by water molecules; clusters of water molecules indicate possible hydration sites, which, in some cases, match those of the major and minor grooves of RNA and DNA double helices; complex hydrogen bond networks characterize the solvation of the nucleotides, resulting in a significant rigidity of the base and its surrounding water molecules. Interestingly, the hydration sites around unpaired RNA bases do not match, in general, the positions that are occupied by the second nucleotide when the base-pair is formed. Conclusions The hydration sites around unpaired RNA bases were found. They do not replicate the atom positions of complementary bases in the Watson-Crick pairs.

Thermo physical and flow properties of CO{sub 2} hydrate slurry - Scientific paper

Energy Technology Data Exchange (ETDEWEB)

Sari, O.; Hu, J.; Eicher, S.; Egolf, P. W. [Institute of Thermal Engineering, University of Applied Sciences of Western Switzerland, Yverdon-les-Bains (Switzerland); Homsy, P. [Nestec, Vevey (Switzerland)

2008-07-01

The apparent viscosity and flow regime of CO{sub 2} hydrate slurry were investigated with a XL7-100 on-line resonant viscometer. Possible reasons for the viscosity changes before and after the nucleation of hydrates are discussed. In addition, super saturation of the CO{sub 2} solution under certain pressure and temperature conditions as well as its density and apparent viscosity were examined. The hydrate's solid fraction and the dissociation enthalpy were evaluated by an on-line Micro DSC system. Real-time coupled multi-electrode array sensor (CMAS) probes were applied to measure the maximal localized corrosion rate of three different materials subjected to CO{sub 2} hydrate slurry and saturated CO{sub 2} solution in the temperature range of 1 to 18 {sup o}C and pressure range of 25 to 30 bar. The density of CO{sub 2} hydrate slurry was also experimentally investigated and the relation between the density and the solid fraction has been established. (author)

Indian continental margin gas hydrate prospects : results of the Indian National Gas Hydrate Program (NGHP) expedition 01

Energy Technology Data Exchange (ETDEWEB)

Collett, T [United States Geological Survey, Denver, CO (United States); Riedel, M. [McGill Univ., Montreal, PQ (Canada). Dept. of Earth and Planetary Sciences; Cochran, J.R. [Columbia Univ., Palisades, NY (United States). Lamont Doherty Earth Observatory; Boswell, R. [United States Dept. of Energy, Morgantown, WV (United States). National Energy Technology Lab; Kumar, P. [Pushpendra Kumar Oil and Natural Gas Corp. Ltd., Mumbai (India). Inst. of Engineering and Ocean Technology; Sathe, A.V. [Oil and Natural Gas Corp. Ltd., Uttaranchal (India). KDM Inst. of Petroleum Exploration

2008-07-01

The geologic occurrence of gas hydrate deposits along the continental margins of India were investigated in the first expedition of the Indian National Gas Hydrate Program (NGHP). The objective was to determine the regional context and characteristics of the gas hydrate deposits through scientific ocean drilling, logging, and analytical activities. A research drill ship was the platform for the drilling operation. The geological and geophysical studies revealed 2 geologically distinct areas with inferred gas hydrate occurrences, notably the passive continental margins of the Indian Peninsula and along the Andaman convergent margin. The NGHP Expedition 01 focused on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these 2 diverse settings. The study established the presence of gas hydrates in Krishna-Godavari, Mahanadi and Andaman basins. Site 10 in the Krishna-Godavari Basin was discovered to be the one of the richest gas hydrate accumulations yet documented, while site 17 in the Andaman Sea had the thickest and deepest gas hydrate stability zone yet known. The existence of a fully-developed gas hydrate system in the Mahanadi Basin was also discovered. Most of the gas hydrate occurrences discovered during this expedition appeared to contain mostly methane which was generated by microbial processes. However, there was also evidence of a thermal origin for a portion of the gas within the hydrates of the Mahanadi Basin and the Andaman offshore area. Gas hydrate in the Krishna-Godavari Basin appeared to be closely associated with large scale structural features, in which the flux of gas through local fracture systems, generated by the regional stress regime, controlled the occurrence of gas hydrate. 3 refs., 1 tab., 2 figs.

Experimental Setup to Characterize Bentonite Hydration Processes; Diseno experimental para la caracterizacion de los procesos de hidratacion de la bentonita

Energy Technology Data Exchange (ETDEWEB)

Bru, A.; Casero, D.; Pastor, J.M.

2001-07-01

We present an experimental setup to follow-up the hydration process of a bentonite. Clay samples, of 2 cm x 12 cm x 12 cm, were made and introduced in a Hele-Shaw cell with two PMM windows and two steel frames. In hydration experiments, a fluid enters by an orifice in the frame, located both at the top and the bottom of the cell, to perform hydration in both senses. To get a uniform hydration we place a diffuser near the orifice. Volume influxes in hydration cells are registered in time. The evolution of the developed interface was recorded on a videotape. The video cameras was fixed to a holder so that the vertical direction in the monitor was the same as the direction of the larger extension of the cell. (Author) 6 refs.

Giordano Bruno crater on the Moon: Detection and Mapping of Hydration Features of Endogenic and/or Exogenic Nature

Science.gov (United States)

Saran Bhiravarasu, Sriram; Bhattacharya, Satadru; Chauhan, Prakash

2017-10-01

We analyze high resolution spectral and spatial data from the recent lunar missions and report the presence of strong hydration features within the inner flank, hummocky floor, ejecta and impact melt deposits of crater Giordano Bruno. Hydroxyl-bearing lithologies at Giordano Bruno are characterized primarily by a prominent absorption feature near 2800 nm, the band minima of which goes beyond 3000 nm. The hydration features are found to be associated with low-Ca pyroxene-bearing noritic lithologies along the inner crater flanks, whereas similar features are also seen within the hummocky crater floor in association with shocked plagioclase-bearing anorthositic lithology. Interestingly, the ejecta blanket is characterized by sharp, narrow features centered near 2800 nm similar to the features previously reported from Compton-Belkovich volcanic complex and central peak of crater Theophilus. The low-Ca pyroxene-bearing rock exposures within the crater inner flanks are characterized by both presence and absence of the hydration features. Enhanced hydration is also seen within the ejecta blanket covering the nearby Harkhebi K and J craters. We also analyze the impact melts and ejecta using radar images at regions interior and exterior to the Giordano Bruno crater rim.Anomalous behaviors of hydration feature associated with low-Ca pyroxene-rich exposures, its nature and occurrences within the impact melt sheets inside the crater along with the ejecta blankets could possibly indicate endogenic and/or exogenic nature of the observed hydration feature. Initial results indicate the presence of strongest hydration feature in the partially shadowed pole-facing slopes (with low-Ca pyroxene-bearing exposures) and its complete absence in the equator-facing sun-lit slopes. This hints at a possible exogenic origin, whereas the same feature occurring (with same mineral) under both sun-lit and shadowed conditions suggest it to be of magmatic origin. We propose that the heterogeneous

The rates measurement of methane hydrate formation and dissociation using micro-drilling system application for gas hydrate exploration

Energy Technology Data Exchange (ETDEWEB)

Bin Dou [Engineering Faculty, China Univ. of Geosciences, Wuhan (China)]|[Inst. of Petroleum Engineering, Technology Univ. of Clausthal (Germany); Reinicke, K.M. [Inst. of Petroleum Engineering, Technology Univ. of Clausthal (Germany); Guosheng Jiang; Xiang Wu; Fulong Ning [Engineering Faculty, China Univ. of Geosciences, Wuhan (China)

2006-07-01

When drilling through gas hydrate bearing formations, the energy supplied by virtue of the drilling process may lead to a destabilization of the hydrates surrounding the wellbore. Therefore, as the number of oil and gas fields being development in deepwater and onshore arctic environments increases, greater emphasis should be placed on quantifying the risks, gas hydrates pose to drilling operations. The qualification of these risks requires a comprehensive understanding of gas hydrate-formation and dissociation as a result of drilling induced processes. To develop the required understanding of gas hydrat formation and dissociation, the authors conducted laboratory experiments by using a micro-drilling system, to study the dissociation rates of methane hydrates contained in a tank reactor. The test facility used is a development of China University of Geosciences. The rates of methane hydrate formation and dissociation in the tank reactor were measured at steady-state conditions at pressures ranging from 0.1 to 25 MPa and temperatures ranging from -5 to 20 C. The experimental results show that the rate of hydrate formation is strongly influenced by the fluid system used to form the hydrates, pressure and temperature, with the influence of the temperature on methane hydrate dissociation being stronger than that of the pressure. Drilling speed, drilling fluids and hydrate dissociation inhibitors were also shown to influence hydrate dissociation rate. The derived results have been used to predict hydrate drilling stability for several drilling fluid systems.

Experimental investigation of methane release from hydrate formation in sandstone through both hydrate dissociation and CO{sub 2} sequestration

Energy Technology Data Exchange (ETDEWEB)

Husebo, J.; Graue, A.; Kvamme, B. [Bergen Univ., Bergen (Norway). Dept. of Physics and Technology; Stevens, J.; Howard, J.J. [ConocoPhillips, Ponca City, OK (United States); Baldwin, B.A. [Green Country Petrophysics LLC, Dewey, OK (United States)

2008-07-01

Large amounts of natural gas trapped in hydrate reservoirs are found in Arctic regions and in deep offshore locations around the world. Natural gas production from hydrate deposits offer significant potential for future energy needs. However, research is needed in order to propose potential production schemes for natural gas hydrates. Natural gas molecules can be freed from hydrate structured cages by depressurization, by heating and by exposing the hydrate to a substance that will form a thermodynamically more stable hydrate structure. This paper provided a comparison of two approaches for releasing methane from methane hydrate in porous sandstone. The study scope covered the dissociation rate of methane hydrate in porous media through depressurization, and also referred to previous work done on producing methane from hydrates in sandstone while sequestering carbon dioxide (CO{sub 2}). The study was conducted in a laboratory setting. The paper discussed the experimental design which included the placing of a pressure- and temperature-controlled sample holder inside the bore of a magnetic resonance imager. The experimental procedures were then outlined, with reference to hydrate formation; carbon dioxide sequestration; hydrate dissociation experiments with constant volume; and hydrate dissociation experiments at constant pressure. The constant volume experiments demonstrated that in order to dissociate a large amount of hydrate, the initial depressurization had to be significantly lower than the hydrate stability pressure. 9 refs., 9 figs.

Microstructure of natural hydrate host sediments

International Nuclear Information System (INIS)

Jones, K.W.; Kerkar, P.B.; Mahajan, D.; Lindquist, W.B.; Feng, H.

2007-01-01

There is worldwide interest in the study of natural gas hydrate because of its potential impact on world energy resources, control on seafloor stability, significance as a drilling hazard and probable impact on climate as a reservoir of a major greenhouse gas. Gas hydrates can (a) be free floating in the sediment matrix (b) contact, but do not cement, existing sediment grains, or (c) actually cement and stiffen the bulk sediment. Seismic surveys, often used to prospect for hydrates over a large area, can provide knowledge of the location of large hydrate concentrations because the hydrates within the sediment pores modify seismic properties. The ability to image a sample at the grain scale and to determine the porosity, permeability and seismic profile is of great interest since these parameters can help in determining the location of hydrates with certainty. We report here on an investigation of the structure of methane hydrate sediments at the grain-size scale using the synchrotron radiation-based computed microtomography (CMT) technique. Work has started on the measurements of the changes occurring as tetrahydrofuran hydrate, a surrogate for methane hydrate, is formed in the sediment

Laboratory-scale simulations with hydrated lime and organic ...

African Journals Online (AJOL)

Laboratory-scale simulations with hydrated lime and organic polymer to evaluate the effect of pre-chlorination on motile Ceratium hirundinella cells during ... When organic material is released from algal cells as a result of physical-chemical impacts on the cells, it may result in tasteand odour-related problems or the ...

Observed gas hydrate morphologies in marine sediment

Energy Technology Data Exchange (ETDEWEB)

Holland, M.; Schultheiss, P.; Roberts, J.; Druce, M. [Geotek Ltd., Daventry, Northamptonshire (United Kingdom)

2008-07-01

The morphology of gas hydrate in marine sediments determines the basic physical properties of the sediment-hydrate matrix and provides information regarding the formation of gas hydrate deposits, and the nature of the disruption that will occur on dissociation. Small-scale morphology is useful in estimating the concentrations of gas hydrate from geophysical data. It is also important for predicting their response to climate change or commercial production. Many remote techniques for gas hydrate detection and quantification depend on hydrate morphology. In this study, morphology of gas hydrate was examined in HYACINTH pressure cores from recent seagoing expeditions. Visual and infrared observations from non-pressurized cores were also used. The expeditions and pressure core analysis were described in detail. This paper described the difference between two types of gas hydrate morphologies, notably pore-filling and grain-displacing. Last, the paper addressed the impact of hydrate morphology. It was concluded that a detailed morphology of gas hydrate is an essential component for a full understanding of the past, present, and future of any gas hydrate environment. 14 refs., 4 figs.

Geophysical approach to gas hydrates studies in Japan

Energy Technology Data Exchange (ETDEWEB)

Sakai, A; Mizukoshi, I [Japan Petroleum Exploration Corp., Tokyo (Japan)

1997-10-22

Studies are under way to estimate by geophysical approaches the saturation of gasses and gas hydrates in the sedimentary rock. Gasses and gas hydrates under stable strata are deemed to be fossil fuel resources. If the characteristics of sonic or elastic waves are related to the amount of gasses or gas hydrates, it will be possible to assess quantitatively the said resources by geophysical approaches. This is the reason why studies have been started for the acquisition of data of a wider frequency range by seismic exploration and about stratum models concerned. In relation to the mean elastic moduli of mixed materials, studies have been made about the applicability of several theories to data from wire-line test boring, to data from seismic exploration, and to pits in zones of perpetual frost. The effort to acquire data of a wider frequency range by seismic exploration aims at filling up the gap between the now-available seismic exploration data and laboratory data. It is believed that these will enable a quantitative assessment of the said resources. 6 refs., 3 figs.

Modeling of Hydration, Compressive Strength, and Carbonation of Portland-Limestone Cement (PLC Concrete

Directory of Open Access Journals (Sweden)

Xiao-Yong Wang

2017-01-01

Full Text Available Limestone is widely used in the construction industry to produce Portland limestone cement (PLC concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel–space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.

Gas hydrates forming and decomposition conditions analysis

Directory of Open Access Journals (Sweden)

А. М. Павленко

2017-07-01

Full Text Available The concept of gas hydrates has been defined; their brief description has been given; factors that affect the formation and decomposition of the hydrates have been reported; their distribution, structure and thermodynamic conditions determining the gas hydrates formation disposition in gas pipelines have been considered. Advantages and disadvantages of the known methods for removing gas hydrate plugs in the pipeline have been analyzed, the necessity of their further studies has been proved. In addition to the negative impact on the process of gas extraction, the hydrates properties make it possible to outline the following possible fields of their industrial use: obtaining ultrahigh pressures in confined spaces at the hydrate decomposition; separating hydrocarbon mixtures by successive transfer of individual components through the hydrate given the mode; obtaining cold due to heat absorption at the hydrate decomposition; elimination of the open gas fountain by means of hydrate plugs in the bore hole of the gushing gasser; seawater desalination, based on the hydrate ability to only bind water molecules into the solid state; wastewater purification; gas storage in the hydrate state; dispersion of high temperature fog and clouds by means of hydrates; water-hydrates emulsion injection into the productive strata to raise the oil recovery factor; obtaining cold in the gas processing to cool the gas, etc.

HYDRATE CORE DRILLING TESTS

Energy Technology Data Exchange (ETDEWEB)

John H. Cohen; Thomas E. Williams; Ali G. Kadaster; Bill V. Liddell

2002-11-01

The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate

Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste

KAUST Repository

Geng, Guoqing; Taylor, Rae; Bae, Sungchul; Herná ndez-Cruz, Daniel; Kilcoyne, David A.; Emwas, Abdul-Hamid M.; Monteiro, Paulo J M

2015-01-01

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C-S-H fibers are composed of particles that are 1.5-2 nm thick and several tens of nanometers long. 29Si NMR shows 47.9% Q1 and 52.1% Q2, with a mean SiO4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C3S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L3,2-edge indicates that Ca2 + in C-S-H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO44 - tetrahedron chain. © 2015 Elsevier Ltd. All rights reserved.

Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste

KAUST Repository

Geng, Guoqing

2015-07-15

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C-S-H fibers are composed of particles that are 1.5-2 nm thick and several tens of nanometers long. 29Si NMR shows 47.9% Q1 and 52.1% Q2, with a mean SiO4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years\\' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C3S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L3,2-edge indicates that Ca2 + in C-S-H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO44 - tetrahedron chain. © 2015 Elsevier Ltd. All rights reserved.

Atomic and nano-scale characterization of a 50-year-old hydrated C3S paste

International Nuclear Information System (INIS)

Geng, Guoqing; Taylor, Rae; Bae, Sungchul; Hernández-Cruz, Daniel; Kilcoyne, David A.; Emwas, Abdul-Hamid; Monteiro, Paulo J.M.

2015-01-01

This paper investigates the atomic and nano-scale structures of a 50-year-old hydrated alite paste. Imaged by TEM, the outer product C–S–H fibers are composed of particles that are 1.5–2 nm thick and several tens of nanometers long. 29 Si NMR shows 47.9% Q 1 and 52.1% Q 2 , with a mean SiO 4 tetrahedron chain length (MCL) of 4.18, indicating a limited degree of polymerization after 50 years' hydration. A Scanning Transmission X-ray Microscopy (STXM) study was conducted on this late-age paste and a 1.5 year old hydrated C 3 S solution. Near Edge X-ray Absorption Fine Structure (NEXAFS) at Ca L 3,2 -edge indicates that Ca 2+ in C–S–H is in an irregular symmetric coordination, which agrees more with the atomic structure of tobermorite than that of jennite. At Si K-edge, multi-scattering phenomenon is sensitive to the degree of polymerization, which has the potential to unveil the structure of the SiO 4 4− tetrahedron chain.

Influence of supplementary cementitious materials on water transport kinetics and mechanical properties of hydrated lime and cement mortars

Directory of Open Access Journals (Sweden)

Ince, C.

2015-06-01

Full Text Available The purpose of this paper is an investigation of the possible role of supplementary cementitious materials (SCMs on water transport kinetics and mechanical properties of hydrated lime (CL90 and Portland cement (PC mortars. The properties of hydrated lime are significantly different from those of cement and therefore modifying fresh and hardened properties of these mortars are vital for mortar/substrate optimisation in masonry construction. The parameters investigated in this paper often are the main barriers to the use of hydrated lime in construction practice. The results show that transfer sorptivity and time to dewater freshly-mixed hydrated lime mortars can be modified when binder is partially replaced with SCMs. Compressive strength of CL90 mortars is increased systematically with the increased replacement levels of SCMs and the results are supported with the microstructural images. The ability to modify the water transport kinetics and mechanical properties allows compatibility between the mortar and the substrate unit in masonry construction.El objetivo de este artículo es investigar el papel de los materiales cementantes suplementarios (SCMs en la cinética de transporte del agua y en las propiedades mecánicas de los morteros de cal hidratada (CL90 y cemento Portland. Las propiedades de la cal hidratada son significativamente diferentes a las del cemento y por lo tanto el control de las propiedades de los morteros frescos y endurecidos es fundamental en la optimización mortero/substrato en albañilería. Los parámetros estudiados en este trabajo son a menudo las principales barreras para el uso de la cal hidratada en la práctica de la construcción. Los resultados indican que la absortividad y el tiempo necesario para deshidratar morteros de cal hidratada recién mezclados pueden ser controlados cuando el conglomerante es parcialmente remplazado por SCMs. La resistencia a compresión de los morteros CL90 aumenta sistem

A high yield process for hydrate formation

Energy Technology Data Exchange (ETDEWEB)

Giavarini, C.; Maccioni, F. [Univ. of Roma La Sapienza, Roma (Italy). Dept. of Chemical Engineering

2008-07-01

Due to the large quantities of natural gas stored in deep ocean hydrates, hydrate reservoirs are a substantial energy resource. Hydrates concentrate methane by as much as a factor of 164. As such, several natural gas transportation and storage systems using gas hydrates have been studied, and many of them are nearing practical use. In these systems, the hydrate is produced as a slurry by a spray process at approximately 7 megapascal (MPa), and then shaped into pellets. The use of a spray process, instead of a conventional stirred vessel is necessary in order to reach high hydrate concentrations in the hydrate-ice system. This paper presented a new procedure to produce a bulk of concentrated methane hydrate in a static traditional reactor at moderate pressure, controlling pressure and temperature in the interval between ice melting and the hydrate equilibrium curve. This paper discussed the experimental procedure which included formation of methane hydrate at approximately 5 MPa and 2 degrees Celsius in a reaction calorimeter at a volume of two liters. Results were also discussed. It was concluded that the procedure seemed suitable for the development of a gas hydrate storage and transport technology. It was found that the spray procedure took more time, but could be sped up and made continuous by using two vessels, one for hydrate formation and the other for hydrate concentration. The advantage was the production of a concentrated hydrate, using a simpler equipment and working at lower pressures respect to the spray process. 9 refs., 5 figs.

Effects of excipients on hydrate formation in wet masses containing theophylline

DEFF Research Database (Denmark)

Airaksinen, Sari; Luukkonen, Pirjo; Jørgensen, Anna

2003-01-01

its dissolution rate. The aim of this study was to investigate whether excipients, such as alpha-lactose monohydrate or the highly water absorbing silicified microcrystalline cellulose (SMCC) can influence the hydrate formation of theophylline. In particular, the aim was to study if SMCC offers...... protection against the formation of theophylline monohydrate relative to alpha-lactose monohydrate in wet masses after an overnight equilibration and the stability of final granules during controlled storage. In addition, the aim was to study the use of spectroscopic methods to identify hydrate formation...... in the formulations containing excipients. Off-line evaluation of materials was performed using X-ray powder diffractometry, near infrared and Raman spectroscopy. alpha-Lactose monohydrate with minimal water absorbing potential was not able to prevent but enhanced hydrate formation of theophylline. Even though SMCC...

Scientific Objectives of the Gulf of Mexico Gas Hydrate JIP Leg II Drilling

Energy Technology Data Exchange (ETDEWEB)

Jones, E. (Chevron); Latham, T. (Chevron); McConnell, D. (AOA Geophysics); Frye, M. (Minerals Management Service); Hunt, J. (Minerals Management Service); Shedd, W. (Minerals Management Service); Shelander, D. (Schlumberger); Boswell, R.M. (NETL); Rose, K.K. (NETL); Ruppel, C. (USGS); Hutchinson, D. (USGS); Collett, T. (USGS); Dugan, B. (Rice University); Wood, W. (Naval Research Laboratory)

2008-05-01

The Gulf of Mexico Methane Hydrate Joint Industry Project (JIP) has been performing research on marine gas hydrates since 2001 and is sponsored by both the JIP members and the U.S. Department of Energy. In 2005, the JIP drilled the Atwater Valley and Keathley Canyon exploration blocks in the Gulf of Mexico to acquire downhole logs and recover cores in silt- and clay-dominated sediments interpreted to contain gas hydrate based on analysis of existing 3-D seismic data prior to drilling. The new 2007-2009 phase of logging and coring, which is described in this paper, will concentrate on gas hydrate-bearing sands in the Alaminos Canyon, Green Canyon, and Walker Ridge protraction areas. Locations were selected to target higher permeability, coarser-grained lithologies (e.g., sands) that have the potential for hosting high saturations of gas hydrate and to assist the U.S. Minerals Management Service with its assessment of gas hydrate resources in the Gulf of Mexico. This paper discusses the scientific objectives for drilling during the upcoming campaign and presents the results from analyzing existing seismic and well log data as part of the site selection process. Alaminos Canyon 818 has the most complete data set of the selected blocks, with both seismic data and comprehensive downhole log data consistent with the occurrence of gas hydrate-bearing sands. Preliminary analyses suggest that the Frio sandstone just above the base of the gas hydrate stability zone may have up to 80% of the available sediment pore space occupied by gas hydrate. The proposed sites in the Green Canyon and Walker Ridge areas are also interpreted to have gas hydrate-bearing sands near the base of the gas hydrate stability zone, but the choice of specific drill sites is not yet complete. The Green Canyon site coincides with a 4-way closure within a Pleistocene sand unit in an area of strong gas flux just south of the Sigsbee Escarpment. The Walker Ridge site is characterized by a sand

Measurement and characterization techniques for thermoelectric materials

Energy Technology Data Exchange (ETDEWEB)

Tritt, T M

1997-07-01

Characterization of thermoelectric materials can pose many problems. A temperature difference can be established across these materials as an electrical current is passed due to the Peltier effect. The thermopower of these materials is quite large and thus large thermal voltages can contribute to many of the measurements necessary to investigate these materials. This paper will discuss the chracterization techniques necessary to investigate these materials and provide an overview of some of the potential systematic errors which can arise. It will also discuss some of the corrections one needs to consider. This should provide an introduction to the characterization and measurement of thermoelectric materials and provide references for a more in depth discussion of the concepts. It should also serve as an indication of the care that must be taken while working with thermoelectric materials.

Physics of enriched uranyl fluoride deposit characterizations using active neutron and gamma interrogation techniques with 252Cf

International Nuclear Information System (INIS)

Wyatt, M.S.; Hannon, T.F.

1998-01-01

A method was developed and successfully applied to characterize large uranyl fluoride (UO 2 F 21 ) deposits at the former Oak Ridge Gaseous Diffusion Plant. These deposits were formed by a wet air in-leakage into the UF 6 process gas lines over a period of years. The resulting UO 2 F 2 is hygroscopic, readily absorbing moisture from the air to form hydrates as UO 2 F 2 -nH 2 O. The ratio of hydrogen to uranium, denoted H/U, can vary from 0--16, and has significant nuclear criticality safety impacts for large deposits. In order to properly formulate the required course of action, a non-intrusive characterization of the distribution of the fissile material within the pipe, its total mass, and amount of hydration was needed. The Nuclear Weapons Identification System (NWIS) previously developed at the Oak Ridge Y-12 Plant for identification of uranium weapons components in storage containers was used to successfully characterize the distribution, hydration, and total mass of these deposits

Effect of Surface Hydration on Antifouling Properties of Mixed Charged Polymers.

Science.gov (United States)

Leng, Chuan; Huang, Hao; Zhang, Kexin; Hung, Hsiang-Chieh; Xu, Yao; Li, Yaoxin; Jiang, Shaoyi; Chen, Zhan

2018-05-07

Interfacial water structure on a polymer surface in water (or surface hydration) is related to the antifouling activity of the polymer. Zwitterionic polymer materials exhibit excellent antifouling activity due to their strong surface hydration. It was proposed to replace zwitterionic polymers using mixed charged polymers because it is much easier to prepare mixed charged polymer samples with much lower costs. In this study, using sum frequency generation (SFG) vibrational spectroscopy, we investigated interfacial water structures on mixed charged polymer surfaces in water, and how such structures change while exposing to salt solutions and protein solutions. The 1:1 mixed charged polymer exhibits excellent antifouling property while other mixed charged polymers with different ratios of the positive/negative charges do not. It was found that on the 1:1 mixed charged polymer surface, SFG water signal is dominated by the contribution of the strongly hydrogen bonded water molecules, indicating strong hydration of the polymer surface. The responses of the 1:1 mixed charged polymer surface to salt solutions are similar to those of zwitterionic polymers. Interestingly, exposure to high concentrations of salt solutions leads to stronger hydration of the 1:1 mixed charged polymer surface after replacing the salt solution with water. Protein molecules do not substantially perturb the interfacial water structure on the 1:1 mixed charged polymer surface and do not adsorb to the surface, showing that this mixed charged polymer is an excellent antifouling material.

Gas hydrate geohazards in shallow sediments and their impact on the design of subsea systems

Energy Technology Data Exchange (ETDEWEB)

Peters, D.; Hatton, G. [Shell Global Solutions Inc., Houston, TX (United States); Mehta, A. [Shell Malaysia Exploration and Production, Sarawak (Malaysia); Hadley, C. [Shell Exploration and Production Inc., Houston, TX (United States)

2008-07-01

This paper described the challenges that exist in producing gas hydrates in deepwater and Arctic environments as a potential source of methane gas. In order to safely produce hydrocarbon reservoirs far beneath near-mudline hydrates, it is important to understand and manage the geohazard risks associated with wells that pass through hydrate-bearing sediments. Since these wells may produce for decades, the temperature of near-mudline sediments may increase above the hydrate dissociation temperature for hundreds of meters from the well. This can result in the release of large quantities of gas causing a volume change that can impact the subsea system in many ways. As the fluids of an underlying reservoir flow to the mudline, heat carried by the fluids warms nearwell sediments and dissociates hydrates, which releases gas that can displace and fracture near well soil. This gas release may be calculated with numerical simulations that model heat and mass transfer in hydrate-bearing sediments. The model simulations require information on the nature and distribution of hydrates within the sediments, the melting behaviour of the hydrates, the thermal and mechanical properties of these shallow sediments, and the amount of hydrates contained in the sediments. However, this information is costly to acquire and characterize with certainty for an offshore development. Therefore, it is important to understand what information, processes, and calculations are needed in order to ensure safe, robust systems to produce the hydrocarbon reservoirs far below the hydrates. It was concluded that the relation between the quantity of gas released and dissociated gas quantities must be well understood. The hydrate concentration is a critical reservoir parameter for reservoirs with severe geohazard risk. 6 refs., 6 figs.

Modifying Cement Hydration with NS@PCE Core-Shell Nanoparticles

Directory of Open Access Journals (Sweden)

Yue Gu

2017-01-01

Full Text Available It is generally accepted that fine particles could accelerate cement hydration process, or, more specifically, this accelerating effect can be attributed to additional surface area introduced by fine particles. In addition to this view, the surface state of fine particles is also an important factor, especially for nanoparticles. In the previous study, a series of nano-SiO2-polycarboxylate superplasticizer core-shell nanoparticles (NS@PCE were synthesized, which have a similar particle size distribution but different surface properties. In this study, the impact of NS@PCE on cement hydration was investigated by heat flow calorimetry, mechanical property measurement, XRD, and SEM. Results show that, among a series of NS@PCE, NS@PCE-2 with a moderate shell-core ratio appeared to be more effective in accelerating cement hydration. As dosage increases, the efficiency of NS@PCE-2 would reach a plateau which is quantified by various characteristic values. Compressive strength results indicate that strength has a linear correlation with cumulative heat release. A hypothesis was proposed to explain the modification effect of NS@PCE, which highlights a balance between initial dispersion and pozzolanic reactivity. This paper provides a new understanding for the surface modification of supplementary cementitious materials and their application and also sheds a new light on nano-SiO2 for optimizing cement-based materials.

Growth of a Hydrate Mound in the Sea of Japan over 300 ka as Revealed by U-Th Ages of MDAC and by H2S Concentrations of Massive Hydrates

Science.gov (United States)

Matsumoto, R.; Snyder, G. T.; Hiruta, A.; Kakizaki, Y.; Huang, C. Y.; Shen, C. C.

2017-12-01

The geological and geophysical exploration of gas hydrate in the Sea of Japan has revealed that hydrates occur as thick massive deposits within gas chimneys which often give rise to pingo-like hydrate mounds on the seafloor. We examine one case in which LWD has demonstrated anomalous profiles including both very low natural gamma ray (<10 API) and high acoustic velocities (2.5 to 3.5 km/s) extending down to 120mbsf, the base of gas hydrate stability (BGHS)[1]. Both conventional and pressure coring have confirmed thick, massive deposits of pure-gas hydrates. Hydrates in the shallow subsurface (< 20mbsf) are characterized by high H2S concentrations corresponding to AOM-induced production of HS-. The deeper hydrates generally have negligible amounts of H2S, with occasional exceptions in which H2S is moderately high. These observations lead us to conclude that both the re-equilibration and growth of hydrates in high CH4 and low to zero H2S conditions has continued during burial, and that this ongoing growth is an essential processes involved in the development of massive hydrates in the Sea of Japan.Regardless of depth, the Japan Sea gas hydrates are closely associated with 13-C depleted, methane-derived authigenic carbonates (MDACs). These MDACs are considered to have been formed at near-SMT depths as a response to increased alkalinity caused by AOM and, as such, MDACs are assumed to represent approximate paleo-seafloor at times of enhanced methane flux and intensive accumulation of gas hydrate in shallow subsurface. U-Th ages of MDACs collected from various depths in a mound-chimney system in central Joetsu Spur have revealed that the paleo-seafloor of 300 ka is presently situated at 30 to 55 mbsf within the gas chimney, in contrast to off-mound sites where it is situated at 100 mbsf. This suggests that at 300 ka the mound stood as a "hydrate-pingo" of 70 m high relative to the surrounding sea floor. At this time, the BGHS shoaled upwards 10m due to eustatic sea

Material stabilization characterization management plan

International Nuclear Information System (INIS)

GIBSON, M.W.

1999-01-01

This document presents overall direction for characterization needs during stabilization of SNM at the Plutonium Finishing Plant (PFP). Technical issues for needed data and equipment are identified. Information on material categories and links to vulnerabilities are given. Comparison data on the material categories is discussed to assist in assessing the relative risks and desired processing priority

Characterization of internal structure of hydrated agar and gelatin matrices by cryo-SEM

KAUST Repository

Rahbani, Janane; Behzad, Ali Reza; Khashab, Niveen M.; Al-Ghoul, Mazen

2012-01-01

There has been a considerable interest in recent years in developing polymer gel matrices for many important applications such as 2DE for quantization and separation of a variety of proteins and drug delivery system to control the release of active agents. However, a well-defined knowledge of the ultrastructures of the gels has been elusive. In this study, we report the characterization of two different polymers used in 2DE: Gelatin, a naturally occurring polymer derived from collagen (protein) and agar, a polymer of polysaccharide (sugar) origin. Low-temperature SEM is used to examine the internal structure of these gels in their frozen natural hydrated states. Results of this study show that both polymers have an array of hollow cells that resembles honeycomb structures. While agar pores are almost circular, the corresponding Gaussian curve is very broad exhibiting a range of radii from nearly 370 to 700 nm. Gelatin pores are smaller and more homogeneous reflecting a narrower distribution from nearly 320 to 650 nm. Overall, these ultrastructural findings could be used to correlate with functions of the polymers. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of internal structure of hydrated agar and gelatin matrices by cryo-SEM

KAUST Repository

Rahbani, Janane

2012-12-26

There has been a considerable interest in recent years in developing polymer gel matrices for many important applications such as 2DE for quantization and separation of a variety of proteins and drug delivery system to control the release of active agents. However, a well-defined knowledge of the ultrastructures of the gels has been elusive. In this study, we report the characterization of two different polymers used in 2DE: Gelatin, a naturally occurring polymer derived from collagen (protein) and agar, a polymer of polysaccharide (sugar) origin. Low-temperature SEM is used to examine the internal structure of these gels in their frozen natural hydrated states. Results of this study show that both polymers have an array of hollow cells that resembles honeycomb structures. While agar pores are almost circular, the corresponding Gaussian curve is very broad exhibiting a range of radii from nearly 370 to 700 nm. Gelatin pores are smaller and more homogeneous reflecting a narrower distribution from nearly 320 to 650 nm. Overall, these ultrastructural findings could be used to correlate with functions of the polymers. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of internal structure of hydrated agar and gelatin matrices by cryo-SEM.

Science.gov (United States)

Rahbani, Janane; Behzad, Ali R; Khashab, Niveen M; Al-Ghoul, Mazen

2013-02-01

There has been a considerable interest in recent years in developing polymer gel matrices for many important applications such as 2DE for quantization and separation of a variety of proteins and drug delivery system to control the release of active agents. However, a well-defined knowledge of the ultrastructures of the gels has been elusive. In this study, we report the characterization of two different polymers used in 2DE: Gelatin, a naturally occurring polymer derived from collagen (protein) and agar, a polymer of polysaccharide (sugar) origin. Low-temperature SEM is used to examine the internal structure of these gels in their frozen natural hydrated states. Results of this study show that both polymers have an array of hollow cells that resembles honeycomb structures. While agar pores are almost circular, the corresponding Gaussian curve is very broad exhibiting a range of radii from nearly 370 to 700 nm. Gelatin pores are smaller and more homogeneous reflecting a narrower distribution from nearly 320 to 650 nm. Overall, these ultrastructural findings could be used to correlate with functions of the polymers. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Artificial Hydration and Nutrition

Science.gov (United States)

... Crisis Situations Pets and Animals myhealthfinder Food and Nutrition Healthy Food Choices Weight Loss and Diet Plans ... Your Health Resources Healthcare Management Artificial Hydration and Nutrition Artificial Hydration and Nutrition Share Print Patients who ...

Alcohol cosurfactants in hydrate antiagglomeration.

Science.gov (United States)

York, J Dalton; Firoozabadi, Abbas

2008-08-28

Because of availability, as well as economical and environmental considerations, natural gas is projected to be the premium fuel of the 21st century. Natural gas production involves risk of the shut down of onshore and offshore operations because of blockage from hydrates formed from coproduced water and hydrate-forming species in natural gas. Industry practice has been usage of thermodynamic inhibitors such as alcohols often in significant amounts, which have undesirable environmental and safety impacts. Thermodynamic inhibitors affect bulk-phase properties and inhibit hydrate formation. An alternative is changing surface properties through usage of polymers and surfactants, effective at 0.5 to 3 weight % of coproduced water. One group of low dosage hydrate inhibitors (LDHI) are kinetic inhibitors, which affect nucleation rate and growth. A second group of LDHI are antiagglomerants, which prevent agglomeration of small hydrate crystallites. Despite great potential, work on hydrate antiagglomeration is very limited. This work centers on the effect of small amounts of alcohol cosurfactant in mixtures of two vastly different antiagglomerants. We use a model oil, water, and tetrahydrofuran as a hydrate-forming species. Results show that alcohol cosurfactants may help with antiagglomeration when traditional antiagglomerants alone are ineffective. Specifically, as low as 0.5 wt. % methanol cosurfactant used in this study is shown to be effective in antiagglomeration. Without the cosurfactant there will be agglomeration independent of the AA concentration. To our knowledge, this is the first report of alcohol cosurfactants in hydrate antiagglomerants. It is also shown that a rhamnolipid biosurfactant is effective down to only 0.5 wt. % in such mixtures, yet a quaternary ammonium chloride salt, i. e., quat, results in hydrate slurries down to 0.01 wt. %. However, biochemical surfactants are less toxic and biodegradable, and thus their use may prove beneficial even if at

Fractional order creep model for dam concrete considering degree of hydration

Science.gov (United States)

Huang, Yaoying; Xiao, Lei; Bao, Tengfei; Liu, Yu

2018-05-01

Concrete is a material that is an intermediate between an ideal solid and an ideal fluid. The creep of concrete is related not only to the loading age and duration, but also to its temperature and temperature history. Fractional order calculus is a powerful tool for solving physical mechanics modeling problems. Using a software element based on the generalized Kelvin model, a fractional order creep model of concrete considering the loading age and duration is established. Then, the hydration rate of cement is considered in terms of the degree of hydration, and the fractional order creep model of concrete considering the degree of hydration is established. Moreover, uniaxial tensile creep tests of dam concrete under different curing temperatures were conducted, and the results were combined with the creep test data and complex optimization method to optimize the parameters of a new creep model. The results show that the fractional tensile creep model based on hydration degree can better describe the tensile creep properties of concrete, and this model involves fewer parameters than the 8-parameter model.

The unfolding effects on the protein hydration shell and partial molar volume: a computational study.

Science.gov (United States)

Del Galdo, Sara; Amadei, Andrea

2016-10-12

In this paper we apply the computational analysis recently proposed by our group to characterize the solvation properties of a native protein in aqueous solution, and to four model aqueous solutions of globular proteins in their unfolded states thus characterizing the protein unfolded state hydration shell and quantitatively evaluating the protein unfolded state partial molar volumes. Moreover, by using both the native and unfolded protein partial molar volumes, we obtain the corresponding variations (unfolding partial molar volumes) to be compared with the available experimental estimates. We also reconstruct the temperature and pressure dependence of the unfolding partial molar volume of Myoglobin dissecting the structural and hydration effects involved in the process.

Hidratação do óxido de magnésio em presença de alumina hidratável Magnesium oxide hydration in presence of hydratable alumina

Directory of Open Access Journals (Sweden)

R. Salomão

2010-07-01

Full Text Available Aluminas hidratáveis são compostos obtidos a partir da calcinação incompleta da gibsita Al(OH3, que podem reagir com água e possuem ação ligante em suspensões cerâmicas. A substituição do cimento de aluminato de cálcio pelas aluminas hidratáveis em concretos refratários contendo óxido de magnésio (MgO pode gerar diversos benefícios em relação às propriedades termomecânicas e refratariedade. No entanto, os efeitos da combinação desses materiais e suas conseqüências para a hidratação do MgO ainda não foram investigados sistemicamente. Neste trabalho, quatro fontes de MgO e aluminas hidratáveis foram combinadas em diferentes proporções e hidratados simultaneamente. Após investigações utilizando difração de raios X, termogravimetria e expansão volumétrica aparente, verificou-se que a relação MgO/Al2O3 e as diferenças de reatividade de cada matéria prima podem afetar significativamente o processo de hidratação. Além disso, foi observado que essa combinação pode ser utilizada como uma interessante técnica anti-hidratação para o MgO.The substitution of calcium aluminate cement by hydratable aluminas in MgO-containing refractory castables can afford several benefits for these materials mechanical properties and refractoriness. Nevertheless, the way that hydratable aluminas affects MgO hydration and its consequences were not yet systemically explored. In the present work, four sources of magnesia and alumina were combined at different ratios and hydrated simultaneously. They were investigated by X-ray diffraction, thermogravimetry and apparent volumetric expansion measurements. It was found that the magnesia/alumina ratio and the differences of reactivity of each raw material can greatly affect both hydration processes, generating different hydrated compounds. It was also verified that this combination can be suitably used as powerful MgO anti-hydration technique.

Investigations into surfactant/gas hydrate relationship

Energy Technology Data Exchange (ETDEWEB)

Rogers, Rudy; Zhang, Guochang; Dearman, Jennifer; Woods, Charles [Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (United States)

2007-03-15

Gas hydrates have unique physical properties portending useful industrial applications of gas storage, gas separation, or water desalination. When gas hydrates were found in the early 1990s to occur naturally and abundantly in seafloors, three other primary interests and concerns emerged: potential new energy source, climate threat from their greenhouse gases, and seafloor instabilities. This paper presents research showing how anionic synthetic surfactants helped develop an industrial gas hydrate storage process for natural gas and how naturally-occurring in-situ anionic biosurfactants influence the formation and placement of gas hydrates in ocean sediments. The catalytic effects, mechanisms, and surface specificities imparted by synthetic surfactants in the gas storage process and imparted by biosurfactants in porous media are discussed. The Bacillus subtilis bacterium that is indigenous to gas hydrate mounds in the Gulf of Mexico was cultured in the laboratory. Its biosurfactant was separated and found to catalyze gas hydrates in porous media. The experiments indicate that seafloor-biosurfactants can be produced rapidly in-situ to achieve threshold concentrations whereby hydrates are promoted. The biosurfactants accumulate and promote hydrate formation on specific mineral surfaces such as sodium montmorillonite. (author)

Influence of silica fume and fly ash on hydration, microstructure and strength of cement based mixtures

Energy Technology Data Exchange (ETDEWEB)

Weng, Kaimao

1992-10-01

The influence of fly ash and silica fume on the hydration, microstructure and strength of cement-based mixtures was investigated. A literature review of the hydration processes, compressive strength development, and microstructure of Portland cement is presented, followed by description of materials and specimens preparation and experimental methodology. It was found that silica fume retards cement hydration at low water/concrete ratios. It reduces calcium hydroxide significantly and increases the amount of hydrates at early ages. Fly ash retards hydration more significantly at high water/concrete ratios than at low ratios. The combination of silica fume and fly ash further retards hydration at one day. Silica fume dominates the reaction with calcium hydroxide. Silica fume significantly increases early strength of mortars and concrete, while fly ash reduces early strength. Silica fume can substantially increase strength of fly ash mortar and concrete after 7 days. Silica fume refines pores in the range 100-500 A, while fly ash mortars exhibit gradual pore refinement as hydration proceeds. Silica fume dominates the pore refinement if used with fly ash. 89 refs., 74 figs., 16 tabs.

Effect of saccharides on the hydration of ordinary Portland cement

NARCIS (Netherlands)

Kochova, K.; Schollbach, K.; Gauvin, F.; Brouwers, H. J.H.

2017-01-01

Recently, the use of natural fibres as a sustainable alternative for reinforcements in cement-based materials has increased significantly. However, these lignocellulose fibres containing saccharides can have important retarding effects on cement hydration. The objective of this study is to

A Hydrate Database: Vital to the Technical Community

Directory of Open Access Journals (Sweden)

D Sloan

2007-06-01

Full Text Available Natural gas hydrates may contain more energy than all the combined other fossil fuels, causing hydrates to be a potentially vital aspect of both energy and climate change. This article is an overview of the motivation, history, and future of hydrate data management using a CODATA vehicle to connect international hydrate databases. The basis is an introduction to the Gas Hydrate Markup Language (GHML to connect various hydrate databases. The accompanying four articles on laboratory hydrate data by Smith et al., on field hydrate data by L?wner et al., on hydrate modeling by Wang et al., and on construction of a Chinese gas hydrate system by Xiao et al. provide details of GHML in their respective areas.

Mechanical Performance of Asphalt Mortar Containing Hydrated Lime and EAFSS at Low and High Temperatures.

Science.gov (United States)

Moon, Ki Hoon; Falchetto, Augusto Cannone; Wang, Di; Riccardi, Chiara; Wistuba, Michael P

2017-07-03

In this paper, the possibility of improving the global response of asphalt materials for pavement applications through the use of hydrated lime and Electric Arc-Furnace Steel Slag (EAFSS) was investigated. For this purpose, a set of asphalt mortars was prepared by mixing two different asphalt binders with fine granite aggregate together with hydrated lime or EAFSS at three different percentages. Bending Beam Rheometer (BBR) creep tests and Dynamic Shear Rheometer (DSR) complex modulus tests were performed to evaluate the material response both at low and high temperature. Then, the rheological Huet model was fitted to the BBR creep results for estimating the impact of filler content on the model parameters. It was found that an addition of hydrated lime and EAFSS up to 10% and 5%, respectively, results in satisfactory low-temperature performance with a substantial improvement of the high-temperature behavior.

Examination of Hydrate Formation Methods: Trying to Create Representative Samples

Energy Technology Data Exchange (ETDEWEB)

Kneafsey, T.J.; Rees, E.V.L.; Nakagawa, S.; Kwon, T.-H.

2011-04-01

Forming representative gas hydrate-bearing laboratory samples is important so that the properties of these materials may be measured, while controlling the composition and other variables. Natural samples are rare, and have often experienced pressure and temperature changes that may affect the property to be measured [Waite et al., 2008]. Forming methane hydrate samples in the laboratory has been done a number of ways, each having advantages and disadvantages. The ice-to-hydrate method [Stern et al., 1996], contacts melting ice with methane at the appropriate pressure to form hydrate. The hydrate can then be crushed and mixed with mineral grains under controlled conditions, and then compacted to create laboratory samples of methane hydrate in a mineral medium. The hydrate in these samples will be part of the load-bearing frame of the medium. In the excess gas method [Handa and Stupin, 1992], water is distributed throughout a mineral medium (e.g. packed moist sand, drained sand, moistened silica gel, other porous media) and the mixture is brought to hydrate-stable conditions (chilled and pressurized with gas), allowing hydrate to form. This method typically produces grain-cementing hydrate from pendular water in sand [Waite et al., 2004]. In the dissolved gas method [Tohidi et al., 2002], water with sufficient dissolved guest molecules is brought to hydrate-stable conditions where hydrate forms. In the laboratory, this is can be done by pre-dissolving the gas of interest in water and then introducing it to the sample under the appropriate conditions. With this method, it is easier to form hydrate from more soluble gases such as carbon dioxide. It is thought that this method more closely simulates the way most natural gas hydrate has formed. Laboratory implementation, however, is difficult, and sample formation is prohibitively time consuming [Minagawa et al., 2005; Spangenberg and Kulenkampff, 2005]. In another version of this technique, a specified quantity of gas

Quantitative Characterization of Nanostructured Materials

Energy Technology Data Exchange (ETDEWEB)

Dr. Frank (Bud) Bridges, University of California-Santa Cruz

2010-08-05

The two-and-a-half day symposium on the "Quantitative Characterization of Nanostructured Materials" will be the first comprehensive meeting on this topic held under the auspices of a major U.S. professional society. Spring MRS Meetings provide a natural venue for this symposium as they attract a broad audience of researchers that represents a cross-section of the state-of-the-art regarding synthesis, structure-property relations, and applications of nanostructured materials. Close interactions among the experts in local structure measurements and materials researchers will help both to identify measurement needs pertinent to real-world materials problems and to familiarize the materials research community with the state-of-the-art local structure measurement techniques. We have chosen invited speakers that reflect the multidisciplinary and international nature of this topic and the need to continually nurture productive interfaces among university, government and industrial laboratories. The intent of the symposium is to provide an interdisciplinary forum for discussion and exchange of ideas on the recent progress in quantitative characterization of structural order in nanomaterials using different experimental techniques and theory. The symposium is expected to facilitate discussions on optimal approaches for determining atomic structure at the nanoscale using combined inputs from multiple measurement techniques.

Synthesis and characterization of alanine boron hydrate for its use in thermal neutron dosimetry.; Sintesis y caracterizacion del borohidrato de alanina para su uso en dosimetria de neutrones termicos.

Energy Technology Data Exchange (ETDEWEB)

Yanez S, J C

1994-07-01

Alanine boron hydrate was synthesized for its possible use as intercomparison dosimeter for thermal neutron irradiation. The irradiations were performed in the Nuclear Reactor of the Nuclear Center of Mexico. The salt was prepared by reacting alanine and boric acid in a (1:1) stoichiometric ratio in neutral pH 7.5 aqueous solution and also in a basic pH 13 solution. The latter reaction was prepared with the addition of ammonia hydroxide (25%). Solutions were stirred and afterwards were let to evaporate. The obtained product in each reaction is a white solid. Dosimeters were prepared with the obtained reaction products and irradiated under thermal neutron flux of 5 x 10{sup 7} n/cm{sup 2} s. For 30 hours. The analysis of irradiated samples was made in a Variant E-15 Electron Paramagnetic Resonance spectrometer. The observed response of the samples prepared with the reaction product at the basic pH is approximately 50% higher than the neutral pH samples. In order to investigate the optimum signal enhancement samples were prepared in a basic pH medium in the following stoichiometric ratios: (1:0.5); (1:0.75); (1:1.25); (1:1.5) and (1:1.75). It was observed that the samples of the reaction (1:0.75) produced the higher response. The response was 2728% higher than the alanine only dosimeters. The reaction product was chemically characterized by X-ray diffraction, Nuclear Magnetic Resonance, Chromatography, Refractometry and Solubility tests. Results indicate that alanine boron hydrate is formed in basic media and in a stoichiometric ratio (1:0.75). The dosimetric characterization of alanine boron hydrate was performed, results are reported. It is concluded that alanine boron hydrate may be a good intercomparison dosimeter for thermal neutron irradiation. (Author).

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

Energy Technology Data Exchange (ETDEWEB)

Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

2005-02-01

Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the

Final Scientific/Technical Report of Gas Hydrate Dynamics on the Alaskan Beaufort Continental Slope: Modeling and Field Characterization

Energy Technology Data Exchange (ETDEWEB)

Hornbach, Matthew J [Southern Methodist Univ., Dallas, TX (United States); Colwell, Frederick S [Oregon State Univ., Corvallis, OR (United States); Harris, Robert [Oregon State Univ., Corvallis, OR (United States)

2017-07-06

Methane Hydrates, a solid form of methane and water, exist at high pressures and low temperatures, occurs on every continental margin on Earth, represents one of the largest reservoirs of carbon on the planet, and, if destabilized, may play an important role in both slope stability and climate change. For decades, researchers have studied methane hydrates with the hope of determining if methane hydrates are destabilizing, and if so, how this destabilization might impact slope stability and ocean/atmosphere carbon budgets. In the past ~5 years, it has become well established that the upper “feather-edge” of methane hydrate stability (intermediate water depths of ~200-500 meters below sea level) represents an important frontier for methane hydrates stability research, as this zone is most susceptible to destabilization due to minor fluctuations in ocean temperature in space and time. The Arctic Ocean—one of the fastest warming regions on Earth—is perhaps the best place to study possible changes to methane hydrate stability due to ocean warming. To address the stability of methane hydrates at intermediate ocean depths, Southern Methodist University in partnership with Oregon State University and The United State Geological Survey at Woods Hole began investigating methane hydrate stability in intermediate water depths below both the US Beaufort Sea and the Atlantic Margin, from 2012-2017. The work was funded by the Department of Energy’s (DOE) National Energy Technology Laboratory (NETL). The key goal of the SMU component of this study was to collect the first ever heat flow data in the Beaufort Sea and compare measured shallow (probe-based1) heat flow values with deeper (BSR-derived2) heat flow values, and from this, determine whether hydrates were in thermal equilibrium. In September 2016, SMU/OSU collected the first ever heat flow measurements in the US Beaufort Sea. Despite poor weather and rough seas, the cruise was a success, with 116 heat flow

Storage capacity of hydrogen in gas hydrates

International Nuclear Information System (INIS)

Tsuda, Takaaki; Ogata, Kyohei; Hashimoto, Shunsuke; Sugahara, Takeshi; Sato, Hiroshi; Ohgaki, Kazunari

2010-01-01

The storage capacity of H 2 in the THF, THT, and furan hydrates was studied by p-V-T measurements. We confirmed that the storage and release processes of H 2 in all hydrates could be performed reversibly by pressure swing without destroying of hydrate cages. H 2 absorption in both THT and furan hydrates is much faster than THF hydrate in spite of same unit-cell structure. On the other hand, the storage amounts of H 2 are coincident in the all additive hydrates and would reach at about 1.0 mass% asymptotically.

Properties of samples containing natural gas hydrate from the JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well, determined using Gas Hydrate And Sediment Test Laboratory Instrument (GHASTLI)

Science.gov (United States)

Winters, W.J.

1999-01-01

As part of an ongoing laboratory study, preliminary acoustic, strength, and hydraulic conductivity results are presented from a suite of tests conducted on four natural-gas-hydrate-containing samples from the Mackenzie Delta JAPEX/JNOC/GSC Mallik 2L-38 gas hydrate research well. The gas hydrate samples were preserved in pressure vessels during transport from the Northwest Territories to Woods Hole, Massachusetts, where multistep tests were performed using GHASTLI (Gas Hydrate And Sediment Test Laboratory Instrument), which recreates pressure and temperature conditions that are stable for gas hydrate. Properties and changes in sediment behaviour were measured before, during, and after controlled gas hydrate dissociation. Significant amounts of gas hydrate occupied the sample pores and substantially increased acoustic velocity and shear strength.

Influence of fluorosurfactants on hydrate formation rates

Energy Technology Data Exchange (ETDEWEB)

Kim, C.U.; Jeong, K.E.; Chae, H.J.; Jeong, S.Y. [Korea Reasearch Inst. of Chemical Technology, Alternative Chemicals/Fuel Research Center, Yuseong-Gu, Daejon (Korea, Republic of)

2008-07-01

Gas hydrates, or clathrates, are ice-like solids that forms when natural gas is in contact with liquid water or ice under high pressure and low temperature. There is significant interest in studying the storage and transportation of gas in the form of hydrates. However, a critical problem impacting the industrial application of gas hydrates for storage and transportation of natural gas is the slow formation rate of natural gas hydrate. Researchers have previously reported on the promotion effect of some additives on gas hydrate formation and hydrate gas content. Fluorosurfactants are significantly superior to nonfluorinated surfactants in wetting action, as well as stability in harsh environments, both thermal and chemical. This paper discussed an experimental investigation into the effects of fluorosurfactants with different ionic types on the formation of methane hydrate. The surfactants used were FSN-100 of DuPont Zonyl as non-ionic surfactant and FC-143 of DuPont as anionic surfactant. The paper discussed the experimental apparatus for methane hydrate formation. It also discussed hydrate formation kinetics and the series of hydrate formation experiments that were conducted in the presence of fluorosurfactants. Last, the paper explored the results of the study. It was concluded that anionic fluorosurfactant of FC-143 had a better promoting effect on methane hydrate formation compared with nonionic surfactant of FSN-100. 8 refs., 2 tabs., 2 figs.

Study on the Promotion Effect of Ionic Liquid on CH4 Hydrate Formation

International Nuclear Information System (INIS)

Shin, Ju-Young; Mun, Sungyong; Kang, Seong-Pil; Kim, Kisub

2013-01-01

In this study, we investigated the kinetics of gas hydrate formation in the presence of ionic liquid (IL). Hydroxyethyl-methyl-morpholinium chloride (HEMM-Cl) was chosen as a material for the promotion effect test. Phase equilibrium curve for CH 4 hydrate with aqueous IL solution was obtained and its induction time and consumed amount of CH 4 gas were also measured. Aqueous solutions containing 20-20,000 ppm of HEMM-Cl was prepared and studied at 70 bar and 274.15 K. To compare the measured results to those of the conventional promoter, sodium dodecyl sulfate was also tested at the same condition. Result showed that the hydrate equilibrium curve was shifted toward higher pressure and lower temperature region. In addition, the induction time on CH 4 hydrate formation in the presence of IL was not shown. The amount of consumed CH 4 was increased with the whole range of tested concentration of IL and the highest consumption of CH 4 happened at 1,000 ppm of HEMM-Cl. HEMM-Cl induced and enhanced the CH 4 hydrate formation with a small amount of addition. Obtained result is expected to be applied for the development of technologies such as gas storage and transport using gas hydrates

Physical Properties of Gas Hydrates: A Review

Energy Technology Data Exchange (ETDEWEB)

Gabitto, Jorge [Prairie View A& M University; Tsouris, Costas [ORNL

2010-01-01

Methane gas hydrates in sediments have been studied by several investigators as a possible future energy resource. Recent hydrate reserves have been estimated at approximately 1016?m3 of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas hydrate is necessary in order to commercially exploit the resource from the natural-gas-hydrate-bearing sediment. The presence of gas hydrates in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of hydrate-bearing sediments is necessary for interpretation of geophysical data collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas hydrates. A brief review of the physical properties of bulk gas hydrates is included. Detection methods, morphology, and relevant physical properties of gas-hydrate-bearing sediments are also discussed.

Microstructural pavement material characterization: some examples

CSIR Research Space (South Africa)

Mgangira, Martin B

2008-07-01

Full Text Available in the way materials respond to loading at the macro-level. The objective of the paper is to demonstrate how Scanning Electron Microscopy (SEM) as an example of advanced measurement techniques was used for material characterization. A range of samples...

Characteristics and interpretation of fracture-filled gas hydrate: an example from the Ulleung Basin, East Sea of Korea

Science.gov (United States)

Lee, Myung Woong; Collett, Timothy S.

2013-01-01

Through the use of 2-D and 3-D seismic data, a total of thirteen sites were selected and drilled in the East Sea of Korea in 2010. A suite of logging-while-drilling (LWD) logs was acquired at each site. LWD logs from the UBGH2-3A well indicate significant gas hydrate in clay-bearing sediments including several zones with massive gas hydrate with a bulk density less than 1.0 g/m3 for depths between 5 and 103 m below the sea floor. The UBGH2-3A well was drilled on a seismically identified chimney structure with a mound feature at the sea floor. Average gas hydrate saturations estimated from the isotropic analysis of ring resistivity and P-wave velocity logs are 80 ± 13% and 47 ± 16%, respectively, whereas they are 46 ± 17% and 45 ± 16%, respectively from the anisotropic analysis. Modeling indicates that the upper part of chimney (between 5 and 45 m below sea floor [mbsf]) is characterized by gas hydrate filling near horizontal fractures (7° dip) and the lower part of chimney (between 45 and 103 mbsf) is characterized by gas hydrate filling high angle fractures on the basis of ring resistivity and P-wave velocity. The anisotropic analysis using P40H resistivity (phase shift resistivity at 32 mHz with 40 inch spacing) and the P-wave velocity yields a gas hydrate saturation of 46 ± 15% and 46 ± 15% respectively, similar to those estimated using ring resistivity and P-wave velocity, but with quite different fracture dip angles. Differences in vertical resolution, depth of investigation, and a finite fracture dimension relative to the tool separation appear to contribute to this discrepancy. Forward modeling of anisotropic resistivity and velocity are essential to identify gas hydrate in fractures and to estimate accurate gas hydrate amounts.

Characterization of skin friction coefficient, and relationship to stratum corneum hydration in a normal Chinese population.

Science.gov (United States)

Zhu, Y H; Song, S P; Luo, W; Elias, P M; Man, M Q

2011-01-01

Studies have demonstrated that some cutaneous biophysical properties vary with age, gender and body sites. However, the characteristics of the skin friction coefficient in different genders and age groups have not yet been well established. In the present study, we assess the skin friction coefficient in a larger Chinese population. A total of 633 subjects (300 males and 333 females) aged 0.15-79 years were enrolled. A Frictiometer FR 770 and Corneometer CM 825 (C&K MPA 5) were used to measure the skin friction coefficient and stratum corneum hydration, respectively, on the dorsal surface of the hand, the forehead and the canthus. In the females, the maximum skin friction coefficients on both the canthus and the dorsal hand skin were observed around the age of 40 years. In the males, the skin friction coefficient on the dorsal hand skin gradually increased from 0 to 40 years of age, and changed little afterward. Skin friction coefficients on some body sites were higher in females than in age-matched males in some age groups. On the canthus and the dorsal hand skin of females, a positive correlation was found between skin friction coefficient and stratum corneum hydration (p skin friction coefficient was positively correlated with stratum corneum hydration on the forehead and the dorsal hand skin (p skin friction coefficient varies with age, gender and body site, and positively correlates with stratum corneum hydration on some body sites. Copyright © 2010 S. Karger AG, Basel.

Clinker mineral hydration at reduced relative humidities

DEFF Research Database (Denmark)

Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Lachowski, Eric E.

1999-01-01

and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6......Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations...

3D pore-type digital rock modeling of natural gas hydrate for permafrost and numerical simulation of electrical properties

Science.gov (United States)

Dong, Huaimin; Sun, Jianmeng; Lin, Zhenzhou; Fang, Hui; Li, Yafen; Cui, Likai; Yan, Weichao

2018-02-01

Natural gas hydrate is being considered as an alternative energy source for sustainable development and has become a focus of research throughout the world. In this paper, based on CT scanning images of hydrate reservoir rocks, combined with the microscopic distribution of hydrate, a diffusion limited aggregation (DLA) model was used to construct 3D hydrate digital rocks of different distribution types, and the finite-element method was used to simulate their electrical characteristics in order to study the influence of different hydrate distribution types, hydrate saturation and formation of water salinity on electrical properties. The results show that the hydrate digital rocks constructed using the DLA model can be used to characterize the microscopic distribution of different types of hydrates. Under the same conditions, the resistivity of the adhesive hydrate digital rock is higher than the cemented and scattered type digital rocks, and the resistivity of the scattered hydrate digital rock is the smallest among the three types. Besides, the difference in the resistivity of the different types of hydrate digital rocks increases with an increase in hydrate saturation, especially when the saturation is larger than 55%, and the rate of increase of each of the hydrate types is quite different. Similarly, the resistivity of the three hydrate types decreases with an increase in the formation of water salinity. The single distribution hydrate digital rock constructed, combined with the law of microscopic distribution and influence of saturation on the electrical properties, can effectively improve the accuracy of logging identification of hydrate reservoirs and is of great significance for the estimation of hydrate reserves.

Imaging systems and materials characterization

International Nuclear Information System (INIS)

Murr, L.E.

2009-01-01

This paper provides a broad background for the historical development and modern applications of light optical metallography, scanning and transmission electron microscopy, field-ion microscopy and several forms of scanning probe microscopes. Numerous case examples illustrating especially synergistic applications of these imaging systems are provided to demonstrate materials characterization especially in the context of structure-property-performance issues which define materials science and engineering

A multivariable model for predicting the frictional behaviour and hydration of the human skin.

Science.gov (United States)

Veijgen, N K; van der Heide, E; Masen, M A

2013-08-01

The frictional characteristics of skin-object interactions are important when handling objects, in the assessment of perception and comfort of products and materials and in the origins and prevention of skin injuries. In this study, based on statistical methods, a quantitative model is developed that describes the friction behaviour of human skin as a function of the subject characteristics, contact conditions, the properties of the counter material as well as environmental conditions. Although the frictional behaviour of human skin is a multivariable problem, in literature the variables that are associated with skin friction have been studied using univariable methods. In this work, multivariable models for the static and dynamic coefficients of friction as well as for the hydration of the skin are presented. A total of 634 skin-friction measurements were performed using a recently developed tribometer. Using a statistical analysis, previously defined potential influential variables were linked to the static and dynamic coefficient of friction and to the hydration of the skin, resulting in three predictive quantitative models that descibe the friction behaviour and the hydration of human skin respectively. Increased dynamic coefficients of friction were obtained from older subjects, on the index finger, with materials with a higher surface energy at higher room temperatures, whereas lower dynamic coefficients of friction were obtained at lower skin temperatures, on the temple with rougher contact materials. The static coefficient of friction increased with higher skin hydration, increasing age, on the index finger, with materials with a higher surface energy and at higher ambient temperatures. The hydration of the skin was associated with the skin temperature, anatomical location, presence of hair on the skin and the relative air humidity. Predictive models have been derived for the static and dynamic coefficient of friction using a multivariable approach. These

Nonlinear fluid dynamics of nanoscale hydration water layer

Science.gov (United States)

Jhe, Wonho; Kim, Bongsu; Kim, Qhwan; An, Sangmin

In nature, the hydration water layer (HWL) ubiquitously exists in ambient conditions or aqueous solutions, where water molecules are tightly bound to ions or hydrophilic surfaces. It plays an important role in various mechanisms such as biological processes, abiotic materials, colloidal interaction, and friction. The HWL, for example, can be easily formed between biomaterials since most biomaterials are covered by hydrophilic molecules such as lipid bilayers, and this HWL is expected to be significant to biological and physiological functions. Here (1) we present the general stress tensor of the hydration water layer. The hydration stress tensor provided the platform form for holistic understanding of the dynamic behaviors of the confined HWL including tapping and shear dynamics which are until now individually studied. And, (2) through fast shear velocity ( 1mm/s) experiments, the elastic turbulence caused by elastic property of the HWL is indirectly observed. Our results may contribute to a deeper study of systems where the HWL plays an important role such as biomolecules, colloidal particles, and the MEMS. This work was supported by the National Research Foundation of Korea(NRF) Grant funded by the Korea government(MSIP) (2016R1A3B1908660).

Synthesis and characterization of ferrous phosphate (vivianite) and its behavior in aqueous media

International Nuclear Information System (INIS)

Diaz F, J.C.

2003-01-01

The synthesis and characterization of materials that can be useful in Environmental Chemistry is very important because their characteristics are exposed and its behavior in chemical phenomena as the sorption in aqueous media is understand to use it in the human being benefit. With the object of using, in a future, the octa hydrated ferrous phosphate (vivianite) as a potential candidate for matrix confinement in contention walls for the storage of radioactive waste of long half life, it was synthesized and it characterized physico chemically and their properties of surface of this compound were evaluated. Presently work was carried out the synthesis and structural characterization of the iron phosphate II by infrared spectroscopy with having Fourier transform, high vacuum scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, the BET multipoint surface area and Moessbauer spectroscopy; as well as, the determination between aqueous media of the isoelectric point and the density of sites of surface of the compound. The octa hydrated ferrous phosphate was obtained pure. The results indicate that the product corresponds to the prospective mineral, the vivianite. The thermal gravimetric analysis demonstrated that the ferrous phosphate is a stable salt after the lost of water. The isoelectric point is since an important parameter because allows to know the behavior of the surface of the material in aqueous systems, in this case the isoelectric point, of the octa hydrated ferrous phosphate, in distilled water is of pH 4.20 and in solution of potassium nitrate 0.5 M is of pH = 3.75. This indicates that the material has an amphoteric surface depending on the pH. On the other hand, the density of active sites of surface obtained by titrations acid-base is of 20 sites by nm 2 . (Author)

Hydration and nutrition knowledge in adolescent swimmers. Does water intake affect urine hydration markers after swimming?

Directory of Open Access Journals (Sweden)

Cesare Altavilla

2017-12-01

Full Text Available Little data exists regarding nutritional knowledge and hydration in adolescent swimmers. The aim of this study was to assess the level of nutrition and hydration knowledge and to describe the fluid balance in adolescent swimmers during training. A study was carried out with a cross-sectional descriptive part and a longitudinal part with repeated measurements over five swimming sessions. Eighty-six adolescent swimmers completed a questionnaire to assess their sport nutrition and hydration knowledge. Fluid balance and urine hydration markers were studied during training. Swimmers showed a limited nutrition knowledge (33.26 % ± SD 12.59 and meagre hydration knowledge (28.61 % ± SD 28.59. Females showed lower scores than male swimmers in nutrition and hydration knowledge. Based on urine specific gravity, swimmers started the training close to the euhydrated threshold (1.019 g/mL ± SD 0.008. Although urine specific gravity and urine colour were reduced after the training, there were minimal changes in body mass (-0.12 Kg ± SD 0.31. Sweat loss (2.67 g/min ± SD 3.23 and the net changes in the fluid balance (-0.22 % ± SD 0.59 were low. The poor knowledge in nutrition and hydration encountered in the swimmers can justify the development of a strategy to incorporate nutritional education programmes for this group. Body water deficit from swimming activity seems to be easily replaced with the water intake to maintain hydration. After the training, the urine of swimmers was diluted regardless of their water intake. Dilution of urine did not reflect real hydration state in swimming.

Geologic implications of gas hydrates in the offshore of India: results of the National Gas Hydrate Program Expedition 01

Science.gov (United States)

Collett, Timothy S.; Boswell, Ray; Cochran, J.R.; Kumar, Pushpendra; Lall, Malcolm; Mazumdar, Aninda; Ramana, Mangipudi Venkata; Ramprasad, Tammisetti; Riedel, Michael; Sain, Kalachand; Sathe, Arun Vasant; Vishwanath, Krishna

2014-01-01

The Indian National Gas Hydrate Program Expedition 01 (NGHP-01) is designed to study the occurrence of gas hydrate along the passive continental margin of the Indian Peninsula and in the Andaman convergent margin, with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. The NGHP-01 expedition established the presence of gas hydrates in the Krishna-Godavari and Mahanadi Basins, and the Andaman Sea. The expedition discovered in the Krishna-Godavari Basin one of the thickest gas hydrate accumulations ever documented, in the Andaman Sea one of the thickest and deepest gas hydrate stability zones in the world, and established the existence of a fully developed gas hydrate petroleum system in all three basins.

Phenylmercuric hydroxide. A highly selective reagent for the hydration of nonconjugated terminal alkynes

International Nuclear Information System (INIS)

Janout, V.; Regen, S.L.

1982-01-01

This article describes an unusual and highly selective method for hydrating nonconjugated terminal alkynes based on the use of phenylmercuric hydroxide as a reagent. Unlike classical mercury catalyzed procedures, sigma-bonded mercury acetylides are formed initially as stable intermediates and subsequently reacted with water under neutral pH to form the corresponding methyl ketone. Isolated yields which have been obtained by using this approach lie in the range of 49-65%. The high selectivity toward nonconjugated terminal alkynes which characterizes the procedure described herein should make it a useful supplement to existing hydration methods

Geochemical Characterization of Concentrated Gas Hydrate Deposits on the Hikurangi Margin, New Zealand: Preliminary Geochemical Cruise Report

Science.gov (United States)

2008-02-29

by staining with ethidium bromide and viewed under UV. The intensity of bands represents the strength of the produce in each sample. Positive and...hydrates with seafloor instability, submarine landslides , and possibly Tsunamis by a freeze-thaw mechanism similar to frost heave [Pecher et al...seeps and mud volcanoes associated with methane seeps and hydrates. The heatflow instrument used was a 3.5-meter-long “violin bow” or “Lister-type

RESULTS FROM THE (1) DATA COLLECTION WORKSHOP, (2) MODELING WORKSHOP AND (3) DRILLING AND CORING METHODS WORKSHOP AS PART OF THE JOINT INDUSTRY PARTICIPATION (JIP) PROJECT TO CHARACTERIZE NATURAL GAS HYDRATES IN THE DEEPWATER GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Stephen A. Holditch; Emrys Jones

2002-09-01

In 2000, Chevron began a project to learn how to characterize the natural gas hydrate deposits in the deepwater portions of the Gulf of Mexico. A Joint Industry Participation (JIP) group was formed in 2001, and a project partially funded by the U.S. Department of Energy (DOE) began in October 2001. The primary objective of this project is to develop technology and data to assist in the characterization of naturally occurring gas hydrates in the deepwater Gulf of Mexico. These naturally occurring gas hydrates can cause problems relating to drilling and production of oil and gas, as well as building and operating pipelines. Other objectives of this project are to better understand how natural gas hydrates can affect seafloor stability, to gather data that can be used to study climate change, and to determine how the results of this project can be used to assess if and how gas hydrates act as a trapping mechanism for shallow oil or gas reservoirs. As part of the project, three workshops were held. The first was a data collection workshop, held in Houston during March 14-15, 2002. The purpose of this workshop was to find out what data exist on gas hydrates and to begin making that data available to the JIP. The second and third workshop, on Geoscience and Reservoir Modeling, and Drilling and Coring Methods, respectively, were held simultaneously in Houston during May 9-10, 2002. The Modeling Workshop was conducted to find out what data the various engineers, scientists and geoscientists want the JIP to collect in both the field and the laboratory. The Drilling and Coring workshop was to begin making plans on how we can collect the data required by the project's principal investigators.

Spatial resolution of gas hydrate and permeability changes from ERT data in LARS simulating the Mallik gas hydrate production test

Science.gov (United States)

Priegnitz, Mike; Thaler, Jan; Spangenberg, Erik; Schicks, Judith M.; Abendroth, Sven

2014-05-01

The German gas hydrate project SUGAR studies innovative methods and approaches to be applied in the production of methane from hydrate-bearing reservoirs. To enable laboratory studies in pilot scale, a large reservoir simulator (LARS) was realized allowing for the formation and dissociation of gas hydrates under simulated in-situ conditions. LARS is equipped with a series of sensors. This includes a cylindrical electrical resistance tomography (ERT) array composed of 25 electrode rings featuring 15 electrodes each. The high-resolution ERT array is used to monitor the spatial distribution of the electrical resistivity during hydrate formation and dissociation experiments over time. As the present phases of poorly conducting sediment, well conducting pore fluid, non-conducting hydrates, and isolating free gas cover a wide range of electrical properties, ERT measurements enable us to monitor the spatial distribution of these phases during the experiments. In order to investigate the hydrate dissociation and the resulting fluid flow, we simulated a hydrate production test in LARS that was based on the Mallik gas hydrate production test (see abstract Heeschen et al., this volume). At first, a hydrate phase was produced from methane saturated saline water. During the two months of gas hydrate production we measured the electrical properties within the sediment sample every four hours. These data were used to establish a routine estimating both the local degrees of hydrate saturation and the resulting local permeabilities in the sediment's pore space from the measured resistivity data. The final gas hydrate saturation filled 89.5% of the total pore space. During hydrate dissociation, ERT data do not allow for a quantitative determination of free gas and remaining gas hydrates since both phases are electrically isolating. However, changes are resolved in the spatial distribution of the conducting liquid and the isolating phase with gas being the only mobile isolating phase

Mechanical Performance of Asphalt Mortar Containing Hydrated Lime and EAFSS at Low and High Temperatures

Directory of Open Access Journals (Sweden)

Ki Hoon Moon

2017-07-01

Full Text Available In this paper, the possibility of improving the global response of asphalt materials for pavement applications through the use of hydrated lime and Electric Arc-Furnace Steel Slag (EAFSS was investigated. For this purpose, a set of asphalt mortars was prepared by mixing two different asphalt binders with fine granite aggregate together with hydrated lime or EAFSS at three different percentages. Bending Beam Rheometer (BBR creep tests and Dynamic Shear Rheometer (DSR complex modulus tests were performed to evaluate the material response both at low and high temperature. Then, the rheological Huet model was fitted to the BBR creep results for estimating the impact of filler content on the model parameters. It was found that an addition of hydrated lime and EAFSS up to 10% and 5%, respectively, results in satisfactory low-temperature performance with a substantial improvement of the high-temperature behavior.

Observation of ice sheet formation on methane and ethane gas hydrates using a scanning confocal microscopy

Energy Technology Data Exchange (ETDEWEB)

Nagao, J.; Shimomura, N.; Ebinuma, T.; Narita, H. [National Inst. of Advanced Industrial Science and Technology, Toyohira, Sapporo (Japan). Methane Hydrate Research Lab.

2008-07-01

sublimation rate. The temperature of ice sheet formation and variation in ice sheet thicknesses were well characterized in this study, which also explained why propane gas hydrates do not exhibit self-preservation. 12 refs., 7 figs.

Quantitative study of Portland cement hydration by X-ray diffraction/Rietveld analysis and independent methods

International Nuclear Information System (INIS)

Scrivener, K.L.; Fuellmann, T.; Gallucci, E.; Walenta, G.; Bermejo, E.

2004-01-01

X-ray diffraction (XRD) is a powerful technique for the study of crystalline materials. The technique of Rietveld refinement now enables the amounts of different phases in anhydrous cementitious materials to be determined to a good degree of precision. This paper describes the extension of this technique to a pilot study of the hydration of a typical Portland cement. To validate this XRD-Rietveld analysis technique, its results were compared with independent measures of the same materials by the analysis of backscattered electron images (BSE/IA) and thermogravimetric analysis (TGA). In addition, the internal consistency of the measurements was studied by comparing the XRD estimates of the amounts of hydrates formed with the amounts expected to form from the XRD estimates of the amounts of anhydrous materials reacted

Dissolution of Hydrocarbon Gas Hydrates in Seawater at 1030-m; Effects of Porosity, Structure, and Compositional Variation as Determined by High-Definition Video and SEM Imaging.

Science.gov (United States)

Stern, L. A.; Peltzer, E. T.; Durham, W. B.; Kirby, S. H.; Brewer, P. G.; Circone, S.; Rehder, G.

2002-12-01

We compare dissolution rates of pure, porous, compacted, and oil-contaminated sI methane hydrate and sII methane-ethane hydrate to rates measured previously on pure, compacted, sI methane hydrate and sI carbon dioxide hydrate (Rehder et al., Fall AGU 2001). Laboratory-synthesized test specimens were used in both studies, allowing characterization of test materials prior to their transport and exposure to seawater at 1030-meter depth on the Monterey Canyon seafloor, off coastal Moss Landing, CA. Although pressure and temperature (P-T) conditions at this site are within the nominal P-T equilibrium fields of all gas hydrates tested here, the seawater is undersaturated with respect to the hydrate-forming gas species. Hence, samples dissolve with time, at a rate dependent on water current flow. Four samples were deployed in this second experiment: (1) pure, 30% porous methane hydrate; (2) pure, compacted methane hydrate; (3) pure methane hydrate compacted and then contaminated with a low-T mineral oil; and (4) pure, compacted sII methane-ethane hydrate with methane:ethane molar ratio 0.72. Samples were transferred by pressure vessel at 0 ° C and 15 MPa to the seafloor observatory via the MBARI remotely operated vehicle Ventana. Samples were then exposed to the deep ocean environment and monitored by HDTV camera for several hours at the beginning and end of a 25-hour period. Local current speed and direction were also measured throughout the experiment. Those samples that did not undergo complete dissolution after 25 h were successfully recovered to the laboratory for subsequent analysis by scanning electron microscopy (SEM). Previously, video analysis showed dissolution rates corresponding to 4.0 +/- 0.5 mmole CO2/m2 s for compacted CO2 hydrate samples, and 0.37 +/- 0.03 mmole CH4/m2s for compacted methane hydrate samples (Rehder et al, AGU 2001). The ratio of dissolution rates fits a simple diffusive boundary layer model that incorporates relative gas solubilities

Modeling Nanomechanical Behavior of Calcium-Silicate-Hydrate

Science.gov (United States)

2012-08-01

coefficient is effective in making the C-S-H matrix stronger. However, increasing packing density also makes the material response more brittle ...16102-16107 Pellenq, R.J. –M and Van Damme, Henri., 2004, Why Does Concrete set?: The nature of Cohesion Forces in hardened Cement-Based...Hydrated Nanocomposites: Concrete, Bone , and Shale. J. Am. Ceram. Soc., 90(9): 2677-2692. Wu, Jianzhong. and John M. Prausnitz. 2002. Generalizations for

An Improved Clearing and Mounting Solution to Replace Chloral Hydrate in Microscopic Applications

Directory of Open Access Journals (Sweden)

Thomas S. Villani

2013-05-01

Full Text Available Premise of the study: This study presents Visikol™, a new proprietary formulation that can be used as an efficient replacement for chloral hydrate as a clearing agent for microscopic examination. In the United States, chloral hydrate is regulated and therefore difficult to acquire. Methods and Results: Fresh and dry samples of the following plants: ginger (Zingiber officinale, maté (Ilex paraguariensis, lime basil (Ocimum americanum, oregano (Origanum vulgare, and mouse-ear cress (Arabidopsis thaliana, were cleared using Visikol or chloral hydrate solution and compared using a light microscope. Conclusions: This new method can be used successfully to clear specimens, allowing identification of diagnostic characteristics for the identification of plant materials. Visikol is as effective as chloral hydrate in providing clarity and resolution of all tissues examined. Tissues become transparent, allowing observation of deeper layers of cells and making it effective in research, botanical and quality control, and for educational applications.

Using Virtual Testing for Characterization of Composite Materials

Science.gov (United States)

Harrington, Joseph

Composite materials are finally providing uses hitherto reserved for metals in structural systems applications -- airframes and engine containment systems, wraps for repair and rehabilitation, and ballistic/blast mitigation systems. They have high strength-to-weight ratios, are durable and resistant to environmental effects, have high impact strength, and can be manufactured in a variety of shapes. Generalized constitutive models are being developed to accurately model composite systems so they can be used in implicit and explicit finite element analysis. These models require extensive characterization of the composite material as input. The particular constitutive model of interest for this research is a three-dimensional orthotropic elasto-plastic composite material model that requires a total of 12 experimental stress-strain curves, yield stresses, and Young's Modulus and Poisson's ratio in the material directions as input. Sometimes it is not possible to carry out reliable experimental tests needed to characterize the composite material. One solution is using virtual testing to fill the gaps in available experimental data. A Virtual Testing Software System (VTSS) has been developed to address the need for a less restrictive method to characterize a three-dimensional orthotropic composite material. The system takes in the material properties of the constituents and completes all 12 of the necessary characterization tests using finite element (FE) models. Verification and validation test cases demonstrate the capabilities of the VTSS.

Seismic reflections associated with submarine gas hydrates

Energy Technology Data Exchange (ETDEWEB)

Andreassen, K

1996-12-31

Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

Seismic reflections associated with submarine gas hydrates

Energy Technology Data Exchange (ETDEWEB)

Andreassen, K.

1995-12-31

Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

A new educational tool to learn about hydration: taste workshops for children.

Science.gov (United States)

Valero Gaspar, Teresa; Rodríguez-Alonso, Paula; Ruiz Moreno, Emma; Del Pozo de la Calle, Susana; Ávila Torres, José Manuel; Varela Moreiras, Gregorio

2016-07-13

Nutrition education contributes to children´s understanding and practice of healthy lifestyles behaviors. Having a well hydration status is an essential topic, especially since children are a vulnerable population who are much more  prone to dehydration than adults are. The approval of the Report on the European Gastronomic Heritage: Cultural and Educational Aspects in 2014 served as starting point to work on innovative audio-visual and multimedia materials for children. The Spanish Nutrition Foundation (FEN) and the Royal Academy of Gastronomy (RAG), in collaboration with the Ministry of Education, Culture and Sport in Spain (MECD),  developed educational videos for schoolchildren to learn about food, nutrition and gastronomy, specially, the importance of being hydrated. To develop a serial of videos for children between 3 and 9 years old with nutrition and cooking lessons to be used as educational resources in the official curricula. Fourteen chapters related to food, nutrition, gastronomy, physical activity and hydration to be used to record videos were designed and tested. A nutritionist, a chef and two puppets were the main characters acting in the videos.  The chapters were assembled in nine videos that included five sections: introduction, video lesson, recipes -in case of hydration, recipes with different water content foods were recorded-, what have you learntand check your knowledge. A summary of the new educational material was officially presented at the Spain Pavilion during the Expo Milano 2015. Moreover, they are included as education  tool for teachers in the new PANGEI Programme (Food, Nutrition and Gastronomy for Infantile Education) conjointly launched by FEN, RAG and MEDC. Taste workshops are useful as innovative nutrition education tools to reinforce language, listening and motor skills as well as food and nutrition concepts, and specially, the importance of being well hydrated.

Ultra-thin, conformal, and hydratable color-absorbers using silk protein hydrogel

Science.gov (United States)

Umar, Muhammad; Min, Kyungtaek; Jo, Minsik; Kim, Sunghwan

2018-06-01

Planar and multilayered photonic devices offer unprecedented opportunities in biological and chemical sensing due to strong light-matter interactions. However, uses of rigid substances such as semiconductors and dielectrics confront photonic devices with issues of biocompatibility and a mechanical mismatch for their application on humid, uneven, and soft biological surfaces. Here, we report that favorable material traits of natural silk protein led to the fabrication of an ultra-thin, conformal, and water-permeable (hydratable) metal-insulator-metal (MIM) color absorber that was mapped on soft, curved, and hydrated biological interfaces. Strong absorption was induced in the MIM structure and could be tuned by hydration and tilting of the sample. The transferred MIM color absorbers reached the exhibition of a very strong resonant absorption in the visible and near infra-red ranges. In addition, we demonstrated that the conformal resonator could function as a refractometric glucose sensor applied on a contact lens.

Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

Science.gov (United States)

Murshed, M Mangir; Schmidt, Burkhard C; Kuhs, Werner F

2010-01-14

The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

Development of Magnesium Silicate Hydrate cement system for nuclear waste encapsulation

International Nuclear Information System (INIS)

Zhang, T.; Vandeperre, L.J.; Cheeseman, C.R.

2012-01-01

A novel low pH cement system for encapsulating nuclear industry wastes containing aluminium has been developed using blends of MgO and silica fume (SF). Identification of the hydrated phases in MgO/silica fume samples showed that brucite formed in early stages of hydration and then reacted with the silica fume to produce a magnesium silicate hydrate (M-S-H) gel phase. When all brucite reacts with silica fume a cement system with an equilibrium pH just below 10 was achieved. Selected mixes have been characterized for hydration reactions, setting time and strength development. Mortar samples with w/s ratios of 0.5 and 50% by weight of sand added achieved compressive strengths in excess of 95 MPa after 28 days. The addition of MgCO 3 buffered the early pH and the addition of fine sand particles eliminated shrinkage cracking. The interaction of the optimised mortar with Al metal has been investigated. Al metal strips were firmly bound into the MgO:SF:sand samples and no H 2 gas detected, and this indicates that the novel systems developed in this work have potential for encapsulating certain types of problematic legacy wastes from the nuclear industry. (authors)

Mineralogical characterization of uranium yellow cake concentrates

International Nuclear Information System (INIS)

Hausen, D.M.

1992-01-01

Uranium yellow cake concentrates have been analyzed and characterized mineralogically by means of differential thermal analysis, X-ray diffraction, infrared spectra and wet chemical methods. On the basis of mineralogical methods of characterization, the following four major structural types of yellow cake may be classified: Uranyl Hydroxide Hydrate, UO 2 (OH) 2 nH 2 O; Basic Uranyl Sulfate Hydrate, (UO 2 ) x (SO 4 ) y (OH) s(x-y ).nH 2 O; Sodium Para-Uranate, Na 5 U 7 O 24 and Uranyl Peroxide Hydrate, UO 4 .nH 2 O. In this paper conditions of yellow cake preparation and characterization are described, along with discussion of significance of structural types to the physical and chemical properties of yellow cake production

A systematic multi-step screening of numerous salt hydrates for low temperature thermochemical energy storage

International Nuclear Information System (INIS)

N’Tsoukpoe, Kokouvi Edem; Schmidt, Thomas; Rammelberg, Holger Urs; Watts, Beatriz Amanda; Ruck, Wolfgang K.L.

2014-01-01

Highlights: • We report an evaluation of the potential of salt hydrates for thermochemical storage. • Both theoretical calculations and experimental measurements using TGA/DSC are used. • Salt hydrates offer very low potential for thermochemical heat storage. • The efficiency of classical processes using salt hydrates is very low: typically 25%. • New processes are needed for the use of salt hydrates in thermochemical heat storage. - Abstract: In this paper, the potential energy storage density and the storage efficiency of salt hydrates as thermochemical storage materials for the storage of heat generated by a micro-combined heat and power (micro-CHP) have been assessed. Because salt hydrates used in various thermochemical heat storage processes fail to meet the expectations, a systematic evaluation of the suitability of 125 salt hydrates has been performed in a three-step approach. In the first step general issues such as toxicity and risk of explosion have been considered. In the second and third steps, the authors implement a combined approach consisting of theoretical calculations and experimental measurements using Thermogravimetric Analysis (TGA). Thus, application-oriented comparison criteria, among which the net energy storage density of the material and the thermal efficiency, have been used to evaluate the potential of 45 preselected salt hydrates for a low temperature thermochemical heat storage application. For an application that requires a discharging temperature above 60 °C, SrBr 2 ·6H 2 O and LaCl 3 ·7H 2 O appear to be the most promising, only from thermodynamic point of view. However, the maximum net energy storage density including the water in the water storage tank that they offer (respectively 133 kW h m −3 and 89 kW h m −3 ) for a classical thermochemical heat storage process are not attractive for the intended application. Furthermore, the thermal efficiency that would result from the storage process based on salt hydrates

Seismic modeling of multidimensional heterogeneity scales of Mallik gas hydrate reservoirs, Northwest Territories of Canada

Science.gov (United States)

Huang, Jun-Wei; Bellefleur, Gilles; Milkereit, Bernd

2009-07-01

In hydrate-bearing sediments, the velocity and attenuation of compressional and shear waves depend primarily on the spatial distribution of hydrates in the pore space of the subsurface lithologies. Recent characterizations of gas hydrate accumulations based on seismic velocity and attenuation generally assume homogeneous sedimentary layers and neglect effects from large- and small-scale heterogeneities of hydrate-bearing sediments. We present an algorithm, based on stochastic medium theory, to construct heterogeneous multivariable models that mimic heterogeneities of hydrate-bearing sediments at the level of detail provided by borehole logging data. Using this algorithm, we model some key petrophysical properties of gas hydrates within heterogeneous sediments near the Mallik well site, Northwest Territories, Canada. The modeled density, and P and S wave velocities used in combination with a modified Biot-Gassmann theory provide a first-order estimate of the in situ volume of gas hydrate near the Mallik 5L-38 borehole. Our results suggest a range of 528 to 768 × 106 m3/km2 of natural gas trapped within hydrates, nearly an order of magnitude lower than earlier estimates which did not include effects of small-scale heterogeneities. Further, the petrophysical models are combined with a 3-D finite difference modeling algorithm to study seismic attenuation due to scattering and leaky mode propagation. Simulations of a near-offset vertical seismic profile and cross-borehole numerical surveys demonstrate that attenuation of seismic energy may not be directly related to the intrinsic attenuation of hydrate-bearing sediments but, instead, may be largely attributed to scattering from small-scale heterogeneities and highly attenuate leaky mode propagation of seismic waves through larger-scale heterogeneities in sediments.

Gas Hydrate Storage of Natural Gas

Energy Technology Data Exchange (ETDEWEB)

Rudy Rogers; John Etheridge

2006-03-31

Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a

Quantification of Protein Hydration, Glass Transitions, and Structural Relaxations of Aqueous Protein and Carbohydrate-Protein Systems.

Science.gov (United States)

Roos, Yrjö H; Potes, Naritchaya

2015-06-11

Water distribution and miscibility of carbohydrate and protein components in biological materials and their structural contributions in concentrated solids are poorly understood. In the present study, structural relaxations and a glass transition of protein hydration water and antiplasticization of the hydration water at low temperatures were measured using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) for bovine whey protein (BWP), aqueous glucose-fructose (GF), and their mixture. Thermal transitions of α-lactalbumin and β-lactoglobulin components of BWP included water-content-dependent endothermic but reversible dehydration and denaturation, and exothermic and irreversible aggregation. An α-relaxation assigned to hydration water in BWP appeared at water-content-dependent temperatures and increased to over the range of 150-200 K at decreasing water content and in the presence of GF. Two separate glass transitions and individual fractions of unfrozen water of ternary GF-BWP-water systems contributed to uncoupled α-relaxations, suggesting different roles of protein hydration water and carbohydrate vitrification in concentrated solids during freezing and dehydration. Hydration water in the BWP fraction of GF-BWP systems was derived from equilibrium water sorption and glass transition data of the GF fraction, which gave a significant universal method to quantify (i) protein hydration water and (ii) the unfrozen water in protein-carbohydrate systems for such applications as cryopreservation, freezing, lyophilization, and dehydration of biological materials. A ternary supplemented phase diagram (state diagram) established for the GF-BWP-water system can be used for the analysis of the water distribution across carbohydrate and protein components in such applications.

Distinguishing between hydrated, partially hydrated or unhydrated clinker in hardened concrete using microscopy

NARCIS (Netherlands)

Valcke, S.L.A.; Rooij, M.R. de; Visser, J.H.M.; Nijland, T.G.

2010-01-01

Hydration of clinker particles is since long a topic of interest in both designing and optimizing cement composition and its quantity used in concrete. The interest for carefully observing and also quantifying the type or stage of clinker hydration in hardened cement paste is twofold. Firstly, the

Experimental Study on Hydrate Induction Time of Gas-Saturated Water-in-Oil Emulsion using a High-Pressure Flow Loop

Directory of Open Access Journals (Sweden)

Lv X.F.

2015-11-01

Full Text Available Hydrate is one of the critical precipitates which have to be controlled for subsea flow assurance. The induction time of hydrate is therefore a significant parameter. However, there have been few studies on the induction time of the natural gas hydrate formation in a flow loop system. Consequently, a series of experiments were firstly performed, including water, natural gas and Diesel oil, on the hydrate induction time under various conditions such as the supercooling and supersaturation degree, water cut, anti-agglomerant dosage, etc. The experiments were conducted in a high-pressure hydrate flow loop newly constructed in the China University of Petroleum (Beijing, and dedicated to flow assurance studies. Then, based on previous research, this study puts forward a method for induction time, which is characterized by clear definition, convenient measurement and good generality. Furthermore, we investigated the influences of the experimental parameters and analyzed the experimental phenomena for the hydrate induction time in a flowing system.

Sustainable Nanopozzolan Modified Cement: Characterizations and Morphology of Calcium Silicate Hydrate during Hydration

Directory of Open Access Journals (Sweden)

N. Mohamed Sutan

2015-01-01

Full Text Available There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, energy-dispersive X-ray spectroscopy (EDS, and scanning electron microscopy (SEM were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP of 0.5 water to cement ratio (w/c. Results were then substantiated with compressive strength (CS results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive.

High temperature material characterization and advanced materials development

International Nuclear Information System (INIS)

Ryu, Woo Seog; Kim, D. H.; Kim, S. H. and others

2005-03-01

The study is to characterize the structural materials under the high temperature, one of the most significant environmental factors in nuclear systems. And advanced materials are developed for high temperature and/or low activation in neutron irradiation. Tensile, fatigue and creep properties have been carried out at high temperature to evaluate the mechanical degradation. Irradiation tests were performed using the HANARO. The optimum chemical composition and heat treatment condition were determined for nuclear grade 316NG stainless steel. Nitrogen, aluminum, and tungsten were added for increasing the creep rupture strength of FMS steel. The new heat treatment method was developed to form more stable precipitates. By applying the novel whiskering process, high density SiC/SiC composites with relative density above 90% could be obtained even in a shorter processing time than the conventional CVI process. Material integrated databases are established using data sheets. The databases of 6 kinds of material properties are accessible through the home page of KAERI material division

Characterization of sialon-type materials

Energy Technology Data Exchange (ETDEWEB)

Spencer, Paul Newman [Univ. of California, Berkeley, CA (United States)

1977-06-01

Four sialon-type materials using volcanic ash as a raw material were characterized and some of their properties were determined. The M3 and M4 materials were identified as β¹--Si₃N₄ sialons; their principal constituent is silicon. The M2 material was identified as a 15R-A1N polytype sialon whose principal constituent is aluminum. The M1 material is a mixture of the two types. An overview of results showing the general structural formulae and the relative order of the materials with respect to various properties as determined by the investigation is presented. It is concluded that of the materials tested, the M2 material shows the most promise as a candidate for meeting some of the current needs for high-temperature materials. It is also concluded that more research is needed in order to explain the low resistance of these materials to thermal shock since their coefficients of thermal expansion are relatively low.

Chemical and mineralogical characterization of two commercial cements and its evolution in function of time; Caracterizacion quimica y mineralogica de dos cementos comerciales y su evolucion en funcion del tiempo

Energy Technology Data Exchange (ETDEWEB)

Gutierrez B, O.

2014-07-01

Mineralogical evolution of Portland cement is studied during hydration process using materials characterization techniques as X-ray diffraction (XRD) and scanning electron microscopy (Sem) in order to analyze the changes in the various cement minerals as alite, belite, celite, during processing to the hydrated phases of tobermorite gel, portlandite and ettringite, respectively, in the cement paste setting at different ages (3, 7 and 28 days). It was found that the hydration process occurs differently in each mineral because of their reaction rates or changes they experience in their crystals during processing of anhydrous to hydrated phase. You may notice changes in the appearance of the dough as you go hydration and the formation of tobermorite gel, portlandite and ettringite. (Author)

THERMODYNAMIC MODEL OF GAS HYDRATES

OpenAIRE

Недоступ, В. И.; Недоступ, О. В.

2015-01-01

The interest to gas hydrates grows last years. Therefore working out of reliable settlement-theoretical methods of definition of their properties is necessary. The thermodynamic model of gas hydrates in which the central place occupies a behaviour of guest molecule in cell is described. The equations of interaction of molecule hydrate formative gas with cell are received, and also an enthalpy and energy of output of molecule from a cell are determined. The equation for calculation of thermody...

STRUCTURAL CHARACTERIZATION OF VOLCANIC ASH OF THE NEVADO DEL RUIZ: ZEOLITE PHASE IDENTIFICATION

Directory of Open Access Journals (Sweden)

Heiddy P. Quiroz

2014-08-01

Full Text Available This paper presents a study of the structural properties obtained from volcanic ash from Nevado del Ruiz located in the Central Range of Andes - Colombia. The volcanic ash samples were subjected to hydration processes and heat treatments in situ during characterization stage material. During the hydration process, which consisted of introducing 2.4875 ± 0.0002g of volcanic ash in 20ml of water for 48 hours, the organic fraction present was removed from the particulate suspension in the aqueous medium. From measurements of X-ray diffraction (XRD, it was observed, that the temperature variations between 323 and 673 K influence the phase formation of zeolite with structures Heulandite -Ca, Stellerita and gmelinite. XRD measurements were performed in vacuum and atmospheric pressure. X'pert Highscore Plus program and simulation Rietveld refinement were used for to obtain the structures of each of the phases. It was found, using the Scherrer equation, that crystallite sizes (Δ (2θ are influenced by changes crystal-chemical caused by hydration, heat treatment and pressure conditions during the characterization. A variation of Δ ( 2θ between 37 and 106.9 nm from XRD measurements was found. It was determined that from 423K in the sample of un-hydrated volcanic ash, the formation of zeolite Stellerita presents with a stable phase up to 673 K.

Indian National Gas Hydrate Program Expedition 01 report

Science.gov (United States)

Collett, Timothy S.; Riedel, M.; Boswell, R.; Presley, J.; Kumar, P.; Sathe, A.; Sethi, A.; Lall, M.V.; ,

2015-01-01

Gas hydrate is a naturally occurring “ice-like” combination of natural gas and water that has the potential to serve as an immense resource of natural gas from the world’s oceans and polar regions. However, gas-hydrate recovery is both a scientific and a technical challenge and much remains to be learned about the geologic, engineering, and economic factors controlling the ultimate energy resource potential of gas hydrate. The amount of natural gas contained in the world’s gas-hydrate accumulations is enormous, but these estimates are speculative and range over three orders of magnitude from about 2,800 to 8,000,000 trillion cubic meters of gas. By comparison, conventional natural gas accumulations (reserves and undiscovered, technically recoverable resources) for the world are estimated at approximately 440 trillion cubic meters. Gas recovery from gas hydrate is hindered because the gas is in a solid form and because gas hydrate commonly occurs in remote Arctic and deep marine environments. Proposed methods of gas recovery from gas hydrate generally deal with disassociating or “melting” in situ gas hydrate by heating the reservoir beyond the temperature of gas-hydrate formation, or decreasing the reservoir pressure below hydrate equilibrium. The pace of energy-related gas hydrate assessment projects has accelerated over the past several years.

Anti-Agglomerator of Tetra-n-Butyl Ammonium Bromide Hydrate and Its Effect on Hydrate-Based CO2 Capture

Directory of Open Access Journals (Sweden)

Rong Li

2018-02-01

Full Text Available Tetra-n-butyl ammonium bromide (TBAB was widely used in the research fields of cold storage and CO2 hydrate separation due to its high phase change latent heat and thermodynamic promotion for hydrate formation. Agglomeration always occurred in the process of TBAB hydrate generation, which led to the blockage in the pipeline and the separation apparatus. In this work, we screened out a kind of anti-agglomerant that can effectively solve the problem of TBAB hydrate agglomeration. The anti-agglomerant (AA is composed of 90% cocamidopropyl dimethylamine and 10% glycerol, which can keep TBAB hydrate of 19.3–29.0 wt. % in a stable state of slurry over 72 h. The microscopic observation of the morphology of the TBAB hydrate particles showed that the addition of AA can greatly reduce the size of the TBAB hydrate particles. CO2 gas separation experiments found that the addition of AA led to great improvement on gas storage capacity, CO2 split fraction and separation factor, due to the increasing of contact area between gas phase and hydrate particles. The CO2 split fraction and separation factor with AA addition reached up to 70.3% and 42.8%, respectively.

METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

Energy Technology Data Exchange (ETDEWEB)

Thomas E. Williams; Keith Millheim; Bill Liddell

2005-03-01

Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Oil-field engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in Arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored the HOT ICE No. 1 on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was designed, constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. Unfortunately, no gas hydrates were encountered in this well; however, a wealth of information was generated

A DFT based equilibrium study of a chemical mixture Tachyhydrite and their lower hydrates for long term heat storage

NARCIS (Netherlands)

Pathak, A.D.; Gaastra - Nedea, S.V.; Zondag, H.A.; Rindt, C.C.M.; Smeulders, D.M.J.

2016-01-01

Chloride based salt hydrates are promising materials for seasonal heat storage. However, hydrolysis, a side reaction, deteriorates, their cycle stability. To improve the kinetics and durability, we have investigated the optimum operating conditions of a chemical mixture of CaCl2 and MgCl2 hydrates.

Changes in the solid state of anhydrous and hydrated forms of sodium naproxen under different grinding and environmental conditions: Evidence of the formation of new hydrated forms.

Science.gov (United States)

Censi, Roberta; Rascioni, Riccardo; Di Martino, Piera

2015-05-01

The aim of the present work was to investigate the solid state change of the anhydrous and hydrate solid forms of sodium naproxen under different grinding and environmental conditions. Grinding was carried out manually in a mortar under the following conditions: at room temperature under air atmosphere (Method A), in the presence of liquid nitrogen under air atmosphere (Method B), at room temperature under nitrogen atmosphere (Method C), and in the presence of liquid nitrogen under nitrogen atmosphere (Method D). Among the hydrates, the following forms were used: a dihydrate form (DSN) obtained by exposing the anhydrous form at 55% RH; a dihydrate form (CSN) obtained by crystallizing sodium naproxen from water; the tetrahydrate form (TSN) obtained by exposing the anhydrous form at 75% RH. The metastable monohydrate form (MSN), previously described in the literature, was not used because of its high physical instability. The chemical stability during grinding was firstly assessed and proven by HPLC. Modification of the particle size and shape, and changes in the solid state under different grinding methods were evaluated by scanning electron microscopy, and X-ray powder diffractometry and thermogravimetry, respectively. The study demonstrated the strong influence of starting form, grinding and environmental conditions on particle size, shape and solid state of recovered sodium naproxen forms. In particular, it was demonstrated that in the absence of liquid nitrogen (Methods A and C), either at air or at nitrogen atmosphere, the monohydrate form (MSN) was obtained from any hydrates, meaning that these grinding conditions favored the dehydration of superior hydrates. The grinding process carried out in the presence of liquid nitrogen (Method B) led to further hydration of the starting materials: new hydrate forms were identified as one pentahydrate form and one hexahydrate form. The hydration was caused by the condensation of the atmospheric water on sodium naproxen