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Sample records for c-phycocyanin hydration water

  1. Hematite photoanode co-functionalized with self-assembling melanin and C-phycocyanin for solar water splitting at neutral pH

    Energy Technology Data Exchange (ETDEWEB)

    Schrantz, Krisztina; Wyss, Pradeep P.; Ihssen, Julian; Toth, Rita; Bora, Debajeet K.; Vitol, Elina A.; Rozhkova, Elena A.; Pieles, Uwe; Thöny-Meyer, Linda; Braun, Artur

    2017-04-01

    tNature provides functional units which can be integrated in inorganic solar cell materials, such as lightharvesting antenna proteins and photosynthetic molecular machineries, and thus help in advancing artifi-cial photosynthesis. Their integration needs to address mechanical adhesion, light capture, charge transferand corrosion resistance. We showed recently how enzymatic polymerization of melanin can immobi-lize the cyanobacterial light harvesting protein C-phycocyanin on the surface of hematite, a prospectivemetal oxide photoanode for solar hydrogen production by water splitting in photoelectrochemical cells.After the optimization of the functionalization procedure, in this work we show reproducible hydrogenproduction, measured parallel to the photocurrent on this bio-hybrid electrode in benign neutral pHphosphate. Over 90% increase compared to the photocurrent of the pristine hematite could be achieved.The hydrogen evolution was monitored during the photoelectrochemical measurement in an improvedphotoelectrochemical cell. The C-phycocyanin-melanin coating on the hematite was shown to exhibit acomb-like fractal pattern. Raman spectroscopy supported the presence of the protein on the hematiteanode surface. The stability of the protein coating is demonstrated during the 2 h GC measurement andthe 24 h operando current density measurement

  2. Synthesis of silver nanoparticles stabilized with C-phycocyanin and for fluorimetric detection of copper ions

    Science.gov (United States)

    Wei, Nana; Hou, Yanhua; Lu, Zongbao; Yu, Huatong; Wang, Quanfu

    2018-01-01

    In this study, C-phycocyanin as protective agent, AgNO3 as raw material and NaBH4 as reducing agent synthesized C-phycocyanin-Ag nanoparticles (PC-AgNPs). The synthesis conditions of PC-AgNPs were determined by optimization. The maximum UV absorption peak of PC-AgNPs at 400 nm. The fluorescence excitation wavelength was 580 nm and the emission wavelength was 625 nm. PC-AgNPs was spherical in transmission electron microscope and the particles sizes were about 10-25 nm. In addition, fluorescence quenching was observed after adding copper ions to PC-AgNPs, which indicated that PC-AgNPs has potential applications in the detection of copper ions in diverse water environment.

  3. Structure and dynamics of interfacial water. Role of hydratation water in the globular proteins dynamics

    International Nuclear Information System (INIS)

    Zanotti, J.M.

    1997-01-01

    This memoir includes five chapters. In the first chapter, are given the elements of the neutrons scattering theory that is used in this study. the second chapter is devoted to a general presentation of the interaction between biological macro molecule and water. The third part is dedicated to the study of the structure and the dynamics of interfacial water in the neighbouring of model systems, the vycor and the amorphous carbon. The results presented in this part are compared with these one relative to water dynamics at the C-phycocyanin surface. This study makes the object of the fourth chapter. Then, in the fifth and last chapter are discussed the results relative to the role of hydratation on the parv-albumin dynamics for which have been combined the neutron quasi elastic incoherent scattering and the nuclear magnetic resonance of the carbon 13 solid in natural abundance

  4. Medical Application of Spirulina platensis Derived C-Phycocyanin

    Directory of Open Access Journals (Sweden)

    Qian Liu

    2016-01-01

    Full Text Available Along with the development of marine biological pharmaceutical research, high-effective and low-toxic drugs and functional foods isolated from marine organisms have become a new field of pharmacy and bromatology. The pharmacological actions, such as anti-inflammation, antioxidation, antitumor, immunological enhancement, and hepatorenal protection of C-phycocyanin (C-PC from Spirulina platensis, have been reported, and C-PC has important value of development and utilization either as drug or as functional food. There are many researches about the various pharmacological actions and mechanisms of C-PC, but related reports are only to some extent integrated deeply and accurately enough, which put some limitations to the further application of C-PC in medicine. Particularly, with the improvement of living standards and attention to health issues, C-PC being a functional food is preferred by more and more people. C-PC is easy to get, safe, and nontoxic; thus, it has a great potential of research and development as a drug or functional food. Here, the separation and purification, physicochemical properties, physiological and pharmacological activities, safety, and some applications are reviewed to provide relevant basis for the development of natural medicine and applied products.

  5. Structure and dynamics of interfacial water. Role of hydratation water in the globular proteins dynamics; Structure et dynamique de l`eau interfaciale. Role de l`eau d`hydratation dans la dynamique des proteines globulaires

    Energy Technology Data Exchange (ETDEWEB)

    Zanotti, J.M.

    1997-01-27

    This memoir includes five chapters. In the first chapter, are given the elements of the neutrons scattering theory that is used in this study. the second chapter is devoted to a general presentation of the interaction between biological macro molecule and water. The third part is dedicated to the study of the structure and the dynamics of interfacial water in the neighbouring of model systems, the vycor and the amorphous carbon. The results presented in this part are compared with these one relative to water dynamics at the C-phycocyanin surface. This study makes the object of the fourth chapter. Then, in the fifth and last chapter are discussed the results relative to the role of hydratation on the parv-albumin dynamics for which have been combined the neutron quasi elastic incoherent scattering and the nuclear magnetic resonance of the carbon 13 solid in natural abundance.

  6. C-phycocyanin extraction assisted by pulsed electric field from Artrosphira platensis.

    Science.gov (United States)

    Martínez, Juan Manuel; Luengo, Elisa; Saldaña, Guillermo; Álvarez, Ignacio; Raso, Javier

    2017-09-01

    This paper assesses the application of pulsed electric fields (PEF) to the fresh biomass of Artrhospira platensis in order to enhance the extraction of C-phycocyanin into aqueous media. Electroporation of A. platensis depended on both electric field strength and treatment duration. The minimum electric field intensity for detecting C-phycocyanin in the extraction medium was 15kV/cm after the application of a treatment time 150μs (50 pulses of 3μs). However higher electric field strength were required when shorter treatment times were applied. Response surface methodology was used in order to investigate the influence of electric field strength (15-25kV/cm), treatment time (60-150μs), and temperature of application of PEF (10-40°C) on C-phycocyanin extraction yield (PEY). The increment of the temperature PEF treatment reduced the electric field strength and the treatment time required to obtain a given PEY and, consequently decreased the total specific energy delivered by the treatment. For example, the increment of temperature from 10°C to 40°C permitted to reduce the electric field strength required to extract 100mg/g d w of C-phycocyanin from 25 to 18kV/cm, and the specific energy input from 106.7 to 67.5kJ/Kg. Results obtained in this investigation demonstrated PEF's potential for selectively extraction C-phycocyanin from fresh A. platensis biomass. The purity of the C-phycocyanin extract obtained from the electroporated cells was higher than that obtained using other techniques based on the cell complete destruction. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Application of an Ultrafine Shearing Method for the Extraction of C-Phycocyanin from Spirulina platensis

    Directory of Open Access Journals (Sweden)

    Jianfeng Yu

    2017-11-01

    Full Text Available Cell disruption is an important step during the extraction of C-phycocyanin from Spirulina platensis. An ultrafine shearing method is introduced and combined with soaking and ultrasonication to disrupt the cell walls of S. platensis efficiently and economically. Five kinds of cell disruption method, including soaking, ultrasonication, freezing-thawing, soaking-ultrafine shearing and soaking-ultrafine shearing-ultrasonication were applied to break the cell walls of S. platensis. The effectiveness of cell breaking was evaluated based on the yield of the C-phycocyanin. The results show that the maximum C-phycocyanin yield was 9.02%, achieved by the soaking-ultrafine shearing-ultrasonication method, followed by soaking (8.43%, soaking-ultrafine shearing (8.89%, freezing and thawing (8.34%, and soaking-ultrasonication (8.62%. The soaking-ultrafine shearing-ultrasonication method is a novel technique for breaking the cell walls of S. platensis for the extraction of C-phycocyanin.

  8. Fed-batch strategy for enhancing cell growth and C-phycocyanin production of Arthrospira (Spirulina) platensis under phototrophic cultivation.

    Science.gov (United States)

    Xie, Youping; Jin, Yiwen; Zeng, Xianhai; Chen, Jianfeng; Lu, Yinghua; Jing, Keju

    2015-03-01

    The C-phycocyanin generated in blue-green algae Arthrospira platensis is gaining commercial interest due to its nutrition and healthcare value. In this study, the light intensity and initial biomass concentration were manipulated to improve cell growth and C-phycocyanin production of A.platensis in batch cultivation. The results show that low light intensity and high initial biomass concentration led to increased C-phycocyanin accumulation. The best C-phycocyanin productivity occurred when light intensity and initial biomass concentration were 300μmol/m(2)/s and 0.24g/L, respectively. The fed-batch cultivation proved to be an effective strategy to further enhance C-phycocyanin production of A.platensis. The results indicate that C-phycocyanin accumulation not only requires nitrogen-sufficient condition, but also needs other nutrients. The highest C-phycocyanin content (16.1%), production (1034mg/L) and productivity (94.8mg/L/d) were obtained when using fed-batch strategy with 5mM medium feeding. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Piroxicam and C-phycocyanin mediated apoptosis in 1,2-dimethylhydrazine dihydrochloride induced colon carcinogenesis: exploring the mitochondrial pathway.

    Science.gov (United States)

    Saini, Manpreet Kaur; Sanyal, Sankar Nath; Vaiphei, Kim

    2012-04-01

    Apoptosis is a synchronized procedure of cell death that is regulated by caspases and proapoptotic proteins. During apoptosis, translocation of cytochrome c, an electron carrier, from mitochondria into the cytosol is regulated by Bcl-2 family members. Cytochrome c in association with an apoptotic protease activating factor (Apaf), a proapoptotic protein essential for cell differentiation and procaspase-9 form the apoptosome complex, which consecutively activates effector caspase, caspase-3, and coordinate the implementation of apoptosis. In the current study, an attempt has been made to gain insight into piroxicam, a traditional nonsteroidal antiinflammatory drug and c-phycocyanin, a biliprotein from Spirulina platensis (cyanobacterium) mediated apoptosis in DMH-induced colon cancer. Male Sprague-Dawley rats were segregated into 5 groups: control, DMH, DMH + piroxicam, DMH + c-phycocyanin, and DMH + piroxicam + c-phycocyanin. Results illustrated that piroxicam and c-phycocyanin treatments stimulate cytochrome c release by downregulating the Bcl-2 (an antiapoptotic protein) expression significantly, while promoting the level of Bax (a proapoptotic protein), thereby activating caspases (caspases-9 and -3) and Apaf-1. The outcomes of the present study clearly signify that piroxicam and c-phycocyanin may mediate mitochondrial-dependent apoptosis in DMH-induced colon cancer. Moreover, apoptosis induction was more apparent in the combination regimen of piroxicam and c-phycocyanin than the individual drugs alone.

  10. 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

    Understanding the state of the hydration water and the microstructure development in a cement paste is likely to be the key for the improvement of its ultimate strength and durability. In order to distinguish and characterize the reacted and unreacted water, the single-particle dynamics of water molecules in hydrated calcium silicates (C 3 S, C 2 S) and aluminates (C 3 A, C 4 AF) were studied by quasi-elastic neutron scattering, QENS. The time evolution of the immobile fraction represents the hydration kinetics and the mobile fraction follows a non-Debye relaxation. Less sophisticated, but more accessible and cheaper techniques, like differential scanning calorimetry, DSC, and near-infrared spectroscopy, NIR, were validated through QENS results and they allow one to easily and quantitatively follow the cement hydration kinetics and can be widely applied on a laboratory scale to understand the effect of additives (i.e., superplasticizers, cellulosic derivatives, etc) on the thermodynamics of the hydration process. DSC provides information on the free water index and on the activation energy involved in the hydration process while the NIR band at 7000 cm -1 monitors, at a molecular level, the increase of the surface-interacting water. We report as an example the effect of two classes of additives widely used in the cement industry: superplasticizers, SPs, and cellulose derivatives. SPs interact at the solid surface, leading to a consistent increment of the activation energy for the processes of nucleation and growth of the hydrated phases. In contrast, the cellulosic additives do not affect the nucleation and growth activation energy, but cause a significant increment in the water availability: in other words the hydration process is more efficient without any modification of the solid/liquid interaction, as also evidenced by the 1 H-NMR. Additional information is obtained by scanning electron microscopy (SEM), ultra small angle neutron scattering (USANS) and wide

  11. Isolation and Purification of C-phycocyanin from Nostoc muscorum (Cyanophyceae and Cyanobacteria Exhibits Antimalarial Activity In vitro

    Directory of Open Access Journals (Sweden)

    Sukla Biswas

    2010-10-01

    Full Text Available The Phycobilin pigments are intensively fluorescent and water soluble. They are categorized into three types, such as pigments containing high, intermediate and low energies are Phycoerythrins (Phycoerythrocyanins, Phycocyanins and Allophycocyanins, respectively. Besides light harvesting, the Phycobiliproteins have shown industrial and biomedical importance. Among them, C-phycocyanin (C-PC has been considered to be the most preferred one. The present study was undertaken to evaluate the antimalarial activity of C-PC isolated from a Nitrogen-fixing Cyanobacterium and Nostoc muscorum. C- PC was extracted and purified by acetone extraction and ammonium sulfate precipitation and dialysis followed by amicon filtration. It was isolated as a~124 kDa water soluble protein molecule. It showed antimalarial activity in vitro against Chloroquine sensitive and resistant Plasmodium falciparum strains. Inhibitory concentrations at 50%, 90% and 95% were determined as 10.27±2.79, 53.53±6.26 and 73.78±6.92 µg/ml against the Chloroquine-sensitive strains; 10.37±1.43, 56.99±11.07 and 72.79±8.59 µg/ml against Chloroquine resistant of Plasmodium falciparum strains. C-PC was found to have antimalarial activity even at a concentration of 3.0 µg/ml. The possible mechanism might be relied on the destruction of polymerization of Haemozoin by binding of C-PC with Ferriprotoporphyrin-IX at the water surface of the plasma membrane.

  12. Effects of C-phycocyanin and Spirulina on Salicylate-Induced Tinnitus, Expression of NMDA Receptor and Inflammatory Genes

    Science.gov (United States)

    Hwang, Juen-Haur; Chen, Jin-Cherng; Chan, Yin-Ching

    2013-01-01

    Effects of C-phycocyanin (C-PC), the active component of Spirulina platensis water extract on the expressions of N-methyl D-aspartate receptor subunit 2B (NR2B), tumor necrosis factor–α (TNF-α), interleukin-1β (IL-1β), and cyclooxygenase type 2 (COX-2) genes in the cochlea and inferior colliculus (IC) of mice were evaluated after tinnitus was induced by intraperitoneal injection of salicylate. The results showed that 4-day salicylate treatment (unlike 4-day saline treatment) caused a significant increase in NR2B, TNF-α, and IL-1β mRNAs expression in the cochlea and IC. On the other hand, dietary supplementation with C-PC or Spirulina platensis water extract significantly reduced the salicylate-induced tinnitus and down-regulated the mRNAs expression of NR2B, TNF-α, IL-1β mRNAs, and COX-2 genes in the cochlea and IC of mice. The changes of protein expression levels were generally correlated with those of mRNAs expression levels in the IC for above genes. PMID:23533584

  13. Effects of C-phycocyanin and Spirulina on salicylate-induced tinnitus, expression of NMDA receptor and inflammatory genes.

    Directory of Open Access Journals (Sweden)

    Juen-Haur Hwang

    Full Text Available Effects of C-phycocyanin (C-PC, the active component of Spirulina platensis water extract on the expressions of N-methyl D-aspartate receptor subunit 2B (NR2B, tumor necrosis factor-α (TNF-α, interleukin-1β (IL-1β, and cyclooxygenase type 2 (COX-2 genes in the cochlea and inferior colliculus (IC of mice were evaluated after tinnitus was induced by intraperitoneal injection of salicylate. The results showed that 4-day salicylate treatment (unlike 4-day saline treatment caused a significant increase in NR2B, TNF-α, and IL-1β mRNAs expression in the cochlea and IC. On the other hand, dietary supplementation with C-PC or Spirulina platensis water extract significantly reduced the salicylate-induced tinnitus and down-regulated the mRNAs expression of NR2B, TNF-α, IL-1β mRNAs, and COX-2 genes in the cochlea and IC of mice. The changes of protein expression levels were generally correlated with those of mRNAs expression levels in the IC for above genes.

  14. Vibrational dynamics of hydration water in amylose

    CERN Document Server

    Cavatorta, F; Albanese, G; Angelini, N

    2002-01-01

    We present a study of the dynamical properties of hydration water associated with amylose helices, based on low-temperature vibrational spectra collected using the TOSCA inelastic spectrometer at ISIS. The structural constraints of the polysaccharidic chains favour the formation of a high-density structure for water, which has been suggested by Imberty and Perez on the basis of conformational analysis. According to this model, hydration water can only enter the pores formed by six adjacent helices and completely fills the pores at a hydration level of about 0.27-g water/g dry amylose. Our measurements show that the dynamical behaviour of hydration water is similar to that observed in high-density amorphous ice. (orig.)

  15. Protective effects of C-phycocyanin on alcohol-induced acute liver injury in mice

    Science.gov (United States)

    Xia, Dong; Liu, Bing; Luan, Xiying; Sun, Junyan; Liu, Nana; Qin, Song; Du, Zhenning

    2016-03-01

    Excessive alcohol consumption leads to liver disease. Extensive evidence suggests that C-phycocyanin (C-PC), a chromophore phycocyanobilin derived from Spirulina platensis, exerts protective effects against chemical-induced organ damage. In this study, we investigated whether C-PC could protect against ethanol-induced acute liver injury. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (CHOL), low-density lipoprotein (LDL), liver homogenate malondialdehyde (MDA), superoxide dismutase (SOD) content were measured, and pathological examination of liver sections were examined. C-PC showed obvious inhibitory effects on serum ALT, AST, TG, CHOL, LDL and MDA, and SOD content significantly increased in the liver. The structure of hepatic lobules was clear, liver sinus returned to normal, and liver cell cords were arranged in neat rows. Cloudiness, swelling, inflammatory cell infiltration and spotty necrosis of liver cells were significantly reduced. Therefore, C-PC can significantly protect against ethanol-induced acute liver injury.

  16. Salubrious effect of C-phycocyanin against oxalate-mediated renal cell injury.

    Science.gov (United States)

    Farooq, Shukkur Muhammed; Asokan, Devarajan; Sakthivel, Ramasamy; Kalaiselvi, Periandavan; Varalakshmi, Palaninathan

    2004-10-01

    C-phycocyanin, a biliprotein pigment found in some blue green algae (Spirulina platensis) with nutritional and medicinal properties, was investigated for its efficacy on sodium oxalate-induced nephrotoxicity in experimentally induced urolithic rats. Male Wistar rats were divided into four groups. Hyperoxaluria was induced in two of these groups by intraperitoneal infusion of sodium oxalate (70 mg/kg), and a pretreatment of phycocyanin (100 mg/kg) as a single oral dosage was given to one of these groups by 1 h prior to sodium oxalate infusion challenges. The study also encompasses an untreated control group and a phycocyanin-alone treated drug control group. The extent of lipid peroxidation (LPO) was evaluated in terms of renal concentrations of MDA, conjugated diene and hydroperoxides. The following assay was performed in the renal tissue (a) antioxidant enzymes such as superoxide dismutase (SOD) and catalase, (b) glutathione metabolizing enzymes such as glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and glucose 6-phosphate dehydrogenase (G6PD), (c) the low molecular weight antioxidants (GSH, vitamins E and C) and protein carbonyl content. The increased concentrations of MDA, conjugated diene and hydroperoxide (index of the lipid peroxidation) were controlled (P antioxidants were appreciably increased (P antioxidants. It was noticed that the activities of antioxidant enzymes and glutathione metabolizing enzymes were considerably stabilized in rats pretreated with phycocyanin. We suggest that phycocyanin protects the integrity of the renal cell by stabilizing the free radical mediated LPO and protein carbonyl, as well as low molecular weight antioxidants and antioxidant enzymes in renal cells. Thus, the present analysis reveals that the antioxidant nature of C-phycocyanin protects the renal cell against oxalate-induced injury and may be a nephroprotective agent.

  17. Chemoprevention of DMH-induced rat colon carcinoma initiation by combination administration of piroxicam and C-phycocyanin.

    Science.gov (United States)

    Saini, Manpreet Kaur; Vaiphei, Kim; Sanyal, Sankar Nath

    2012-02-01

    Cancer research illustrated that combinatorial studies can provide significant improvement in safety and effectiveness over the monotherapy regimens. A combination of two drugs may restrain precancerous colon polyps, opening a new possible opportunity for chemoprevention of colon cancer. In this context, chemopreventive efficacy of a combination regimen of C-phycocyanin, a biliprotein present in Spirulina platensis, a cyanobacterium, which is a selective cycloxygenase-2 (COX-2) inhibitor and piroxicam, a traditional non-steroidal anti-inflammatory drug was considered in 1,2 dimethylhyadrazine (DMH)-induced colon carcinogenesis in rats. Western blotting, immunohistochemistry, DNA fragmentation, fluorescent staining, PGE(2) enzyme immunoassay, and carrageenan-induced paw edema test were performed along with morphological and histological analysis. DMH treatment showed a rich presence of preneoplastic lesions such as multiple plaque lesions, aberrant crypt foci, and well-characterized dysplasia. These features were reduced with piroxicam and C-phycocyanin administration. The number of apoptotic cells was featured prominently in all the groups compared with DMH. DMH treatment revealed intact high molecular weight genomic DNA with no signs of laddering/DNA fragmentation while it was noticeable significantly in control and DMH + piroxicam + C-phycocyanin. DMH group showed highest COX-2 expression and PGE(2) level in comparison with other groups. Doses of piroxicam and C-phycocyanin used in the present study were established at an anti-inflammatory range. A combination regimen of piroxicam and C-phycocyanin, rather than individually has the much greater potential for reduction of DMH-induced colon cancer development and COX-2 being the prime possible target in such chemoprevention.

  18. Separation of water through gas hydrate formation

    DEFF Research Database (Denmark)

    Boch Andersen, Torben; Thomsen, Kaj

    2009-01-01

    Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goal...... of the project was to formulate an alternative separation concept, which can replace the traditional water evaporation process in the sugar production. Work with the separation concept showed that gas hydrates can be used for water separation. The process is not suitable for sugar production because of large...... volumes and the needs for high pressure. The process could be interesting for concentration of heat sensitive, high value products...

  19. Effect of Ultrasonic Extraction on Production and Structural Changes of C-Phycocyanin from Marine Spirulina maxima.

    Science.gov (United States)

    Choi, Woon Yong; Lee, Hyeon Yong

    2018-01-11

    This work first showed that very high amounts of phycocyanins, such as 11.3 mg/mL C-phycocyanin (C-PC), 3.1 mg/mL allophycocyanin (APC), and 0.8 mg/mL phycoerythrin (PE), can be obtained using an ultrasonic extraction process (UE) with a 60 kHz frequency and 3 h of process time at 25 °C, without any other pretreatments. These yields were higher than those from most conventional water extractions at 4 °C for 24 h (Control condition) or at 25 °C for 24 h (WE), namely, 9.8 and 5.7 mg/mL C-PC, 2.3 and 1.2 mg/mL APC, and 0.7 and 0.3 mg/mL PE, respectively. These yields were also shown to be even higher than yields from other reported data. Structural changes in C-PC in the extracts were also found for the first time, according to extraction conditions, showing that the total concentration of C-PC and of the α-subunit of C-PC in the UE were much higher than in the WE, with little difference in the amount of β-subunit of C-PC in the UE or WE. It was also shown that the structural changes in C-PC in the WE decreased both antioxidant and anti-inflammation activities-29.83% vs. 32.09% of α,α-diphenyl-β-picrylhydrazyl (DPPH) scavenging activity and 8.21 vs. 7.25 µM of NO production for the WE and UE, respectively-while the UE, with similar patterns to standard C-PC, showed very high biological effects, which may suggest that the biologically active part is the α-subunit of C-PC, not the β-subunit.

  20. Effect of Ultrasonic Extraction on Production and Structural Changes of C-Phycocyanin from Marine Spirulina maxima

    Directory of Open Access Journals (Sweden)

    Woon Yong Choi

    2018-01-01

    Full Text Available This work first showed that very high amounts of phycocyanins, such as 11.3 mg/mL C-phycocyanin (C-PC, 3.1 mg/mL allophycocyanin (APC, and 0.8 mg/mL phycoerythrin (PE, can be obtained using an ultrasonic extraction process (UE with a 60 kHz frequency and 3 h of process time at 25 °C, without any other pretreatments. These yields were higher than those from most conventional water extractions at 4 °C for 24 h (Control condition or at 25 °C for 24 h (WE, namely, 9.8 and 5.7 mg/mL C-PC, 2.3 and 1.2 mg/mL APC, and 0.7 and 0.3 mg/mL PE, respectively. These yields were also shown to be even higher than yields from other reported data. Structural changes in C-PC in the extracts were also found for the first time, according to extraction conditions, showing that the total concentration of C-PC and of the α-subunit of C-PC in the UE were much higher than in the WE, with little difference in the amount of β-subunit of C-PC in the UE or WE. It was also shown that the structural changes in C-PC in the WE decreased both antioxidant and anti-inflammation activities—29.83% vs. 32.09% of α,α-diphenyl-β-picrylhydrazyl (DPPH scavenging activity and 8.21 vs. 7.25 µM of NO production for the WE and UE, respectively—while the UE, with similar patterns to standard C-PC, showed very high biological effects, which may suggest that the biologically active part is the α-subunit of C-PC, not the β-subunit.

  1. CD59 Underlines the Antiatherosclerotic Effects of C-Phycocyanin on Mice

    Directory of Open Access Journals (Sweden)

    Bing Li

    2013-01-01

    Full Text Available The effects of C-phycocyanin (C-PC on atherosclerosis and the regulatory effects of CD59 gene on anti-atherosclerotic roles of C-PC were investigated. Apolipoprotein E knockout (ApoE(−/− mice were randomly divided into four groups: control group, C-PC treatment group, CD59 transfection group and C-PC+CD59 synergy group. The mice were fed with high-fat-diet and treated with drug intervention at the same time. Results showed the atherosclerotic mouse model was successfully established. CD59 was over-expressed in blood and tissue cells. Single CD59 or C-PC could reduce blood lipid levels and promote the expression of anti-apoptotic Bcl-2 but inhibit pro-apoptotic Fas proteins in endothelial cells. The expression levels of cell cycle protein D1 (Cyclin D1 and mRNA levels of cyclin dependent protein kinase 4 (CDK4 in smooth muscle cells were restrained by CD59 and C-PC. CD59 or C-PC alone could inhibit the formation of atherosclerotic plaque by suppressing MMP-2 protein expression. In addition, C-PC could promote CD59 expression. So both CD59 and C-PC could inhibit the progress of atherosclerosis, and the anti-atherosclerotic effects of C-PC might be fulfilled by promoting CD59 expression, preventing smooth muscle cell proliferation and the apoptosis of endothelial cells, reducing blood fat levels, and at last inhibiting the development of atherosclerosis.

  2. 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…

  3. Investigation of the Structure and Element Composition of C-Phycocyanin Extracted from the Microalgae Spirulina platensis

    CERN Document Server

    Mosulishvili, L M; Kirkesali, E I; Khizanishvili, A I; Frontasyeva, M V; Pavlov, S S; Gundorina, S F

    2002-01-01

    The structure and element composition of C-phycocyanin (C-PC) extracted from the blue-green alga Spirulina platensis were studied. The behavior of structural subunits forming phycobilisomes in the purification process was studied by capillary electrophoresis. Their proportion in high-purity C-PC was determined. The element composition of C-PC of different purity was studied by means of epithermal neutron activation analysis, and metals which may form macromolecular complexes with C-PC were determined (Zn, Cr, Ni, Co, As, Sr, Mo, Ag, Hg). It was shown that contents of toxic metals did not exceed accepted permissible levels for the human organism.

  4. 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

  5. Enhancement of antioxidant activity of C-phycocyanin of Spirulina powder treated with supercritical fluid carbon dioxide

    Directory of Open Access Journals (Sweden)

    Monchai Dejsungkranont

    2017-10-01

    Full Text Available The functionality and activity of proteins can be modified by supercritical fluid CO2 (SCFCO2. The objectives of this study were to investigate the possibility of enhanced antioxidant activity of C-phycocyanin (C-PC proteins from light-harvested Spirulina maxima powder using the SCFCO2 pretreatment and to optimize the SCFCO2 pretreatment conditions enhancing the antioxidant activity of C-PC. The Taguchi method was used to determine the optimum conditions for the SCFCO2 pretreatment. The experimental factors were the pretreatment temperature, pressure, pretreatment mode (static, dynamic and conjugated and duration. The optimal conditions of SCFCO2 pretreatment were: 60 °C, 24.13 MPa and 60 min in static batch mode. Using these pretreatment conditions, the maximum antioxidant activity of C-PC from the treated residual biomass was 410.1 μmole trolox/mg, which was 1.7-fold higher than the untreated biomass (control. The factor that most affected the antioxidant activity of C-PC was temperature (59%. A high pretreatment temperature could damage C-PC, but promoted antioxidant activity. Of note is that this work was the first to explore SCFCO2 treatment enhancing the antioxidant activity of C-PC in Spirulina sp. powder. Keywords: Antioxidant activity, C-phycocyanin, Spirulina sp., Supercritical fluid carbon dioxide pretreatment, Taguchi method

  6. Water Dynamics in the Hydration Shells of Biomolecules

    Science.gov (United States)

    2017-01-01

    The structure and function of biomolecules are strongly influenced by their hydration shells. Structural fluctuations and molecular excitations of hydrating water molecules cover a broad range in space and time, from individual water molecules to larger pools and from femtosecond to microsecond time scales. Recent progress in theory and molecular dynamics simulations as well as in ultrafast vibrational spectroscopy has led to new and detailed insight into fluctuations of water structure, elementary water motions, electric fields at hydrated biointerfaces, and processes of vibrational relaxation and energy dissipation. Here, we review recent advances in both theory and experiment, focusing on hydrated DNA, proteins, and phospholipids, and compare dynamics in the hydration shells to bulk water. PMID:28248491

  7. Production of the α and β Subunits of Spirulina Allophycocyanin and C-Phycocyanin in Escherichia coli : A Comparative Study of Their Antioxidant Activities.

    Science.gov (United States)

    Cherdkiatikul, Thiti; Suwanwong, Yaneenart

    2014-07-01

    Allophycocyanin and c-phycocyanin have been reported to be potent antioxidants. In this work, the genes encoding the apo-proteins of allophycocyanin α (ApcA), allophycocyanin β (ApcB), c-phycocyanin α (CpcA), and c-phycocyanin β (CpcB) from Spirulina platensis were cloned, and the recombinant proteins were produced in Escherichia coli to study their antioxidant effects. All four recombinant phycocyanins could be produced in the soluble form and purified to more than 97% purity. The results of radical scavenging assays showed that the Trolox equivalent values for peroxyl radical scavenging by the ApcA, ApcB, CpcA, and CpcB proteins were 1.81 ± 0.2 µM, 1.98 ± 0.22 µM, 0.95 ± 0.15 µM, and 1.49 ± 0.15 µM, respectively. The IC50 values for hydroxyl radical scavenging of ApcA, ApcB, CpcA, CpcB, and Trolox were 269 ± 9 µg/mL, 190 ± 5 µg/mL, 129 ± 8 µg/mL, 108 ± 4 µg/mL, and 195 ± 12 µg/mL, respectively. These results indicated that allophycocyanin exhibited higher activity than c-phycocyanin in scavenging peroxyl radicals, whereas c-phycocyanin exhibited higher activity than allophycocyanin in scavenging hydroxyl radicals. All of the apo-phycocyanin subunits possessed strong antioxidant activities and can be further developed and applied to the food and drug industries. However, the selection of the most useful antioxidant should depend on the type of targeted free radical to obtain the highest efficiency. © 2014 Society for Laboratory Automation and Screening.

  8. 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.

  9. 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.

  10. Transport of hydrate slurry at high water cut

    OpenAIRE

    Melchuna , Aline; Cameirão , Ana; Herri , Jean-Michel; Ouabbas , Yamina; Glenat , Philippe

    2014-01-01

    Poster; International audience; Oil transportation in pipelines at the end of field production life implies to flow high quantities of water which represents the dominant phase. The process of crystallization of gas hydrates in this system needs to be studied and compared to the opposite one widely studied in the literature where water is the dispersed phase. The laboratory is equipped with the Archimede flow loop where the hydrate crystallization and transport are monitored. The flow loop is...

  11. Hydration of ammonia, methylamine, and methanol in amorphous solid water

    Science.gov (United States)

    Souda, Ryutaro

    2016-02-01

    Interactions of polar protic molecules with amorphous solid water (ASW) have been investigated using temperature-programmed desorption and time-of-flight secondary ion mass spectrometry. The ammonia and methylamine are incorporated into the interior of porous ASW films. They are caged by water molecules and are released during water crystallization. In contrast, the methanol-water interaction is not influenced by pores of ASW. The methanol additives tend to survive water crystallization and are released during ASW film evaporation. The hydration of n-hexane in ASW is influenced significantly by methanol additives because n-hexane is accommodated in a methanol-induced hydration shell.

  12. Probing the hydration water diffusion of macromolecular surfaces and interfaces

    International Nuclear Information System (INIS)

    Ortony, Julia H; Cheng, Chi-Yuan; Franck, John M; Pavlova, Anna; Hunt, Jasmine; Han, Songi; Kausik, Ravinath

    2011-01-01

    We probe the translational dynamics of the hydration water surrounding the macromolecular surfaces of selected polyelectrolytes, lipid vesicles and intrinsically disordered proteins with site specificity in aqueous solutions. These measurements are made possible by the recent development of a new instrumental and methodological approach based on Overhauser dynamic nuclear polarization (DNP)-enhanced nuclear magnetic resonance (NMR) spectroscopy. This technique selectively amplifies 1 H NMR signals of hydration water around a spin label that is attached to a molecular site of interest. The selective 1 H NMR amplification within molecular length scales of a spin label is achieved by utilizing short-distance range (∼r -3 ) magnetic dipolar interactions between the 1 H spin of water and the electron spin of a nitroxide radical-based label. Key features include the fact that only minute quantities (<10 μl) and dilute (≥100 μM) sample concentrations are needed. There is no size limit on the macromolecule or molecular assembly to be analyzed. Hydration water with translational correlation times between 10 and 800 ps is measured within ∼10 A distance of the spin label, encompassing the typical thickness of a hydration layer with three water molecules across. The hydration water moving within this time scale has significant implications, as this is what is modulated whenever macromolecules or molecular assemblies undergo interactions, binding or conformational changes. We demonstrate, with the examples of polymer complexation, protein aggregation and lipid-polymer interaction, that the measurements of interfacial hydration dynamics can sensitively and site specifically probe macromolecular interactions.

  13. Water Intake and Hydration Indices in Healthy European Adults: The European Hydration Research Study (EHRS).

    Science.gov (United States)

    Malisova, Olga; Athanasatou, Adelais; Pepa, Alex; Husemann, Marlien; Domnik, Kirsten; Braun, Hans; Mora-Rodriguez, Ricardo; Ortega, Juan F; Fernandez-Elias, Valentin E; Kapsokefalou, Maria

    2016-04-06

    Hydration status is linked with health, wellness, and performance. We evaluated hydration status, water intake, and urine output for seven consecutive days in healthy adults. Volunteers living in Spain, Germany, or Greece (n = 573, 39 ± 12 years (51.1% males), 25.0 ± 4.6 kg/m² BMI) participated in an eight-day study protocol. Total water intake was estimated from seven-day food and drink diaries. Hydration status was measured in urine samples collected over 24 h for seven days and in blood samples collected in fasting state on the mornings of days 1 and 8. Total daily water intake was 2.75 ± 1.01 L, water from beverages 2.10 ± 0.91 L, water from foods 0.66 ± 0.29 L. Urine parameters were: 24 h volume 1.65 ± 0.70 L, 24 h osmolality 631 ± 221 mOsmol/kg Η2Ο, 24 h specific gravity 1.017 ± 0.005, 24 h excretion of sodium 166.9 ± 54.7 mEq, 24 h excretion of potassium 72.4 ± 24.6 mEq, color chart 4.2 ± 1.4. Predictors for urine osmolality were age, country, gender, and BMI. Blood indices were: haemoglobin concentration 14.7 ± 1.7 g/dL, hematocrit 43% ± 4% and serum osmolality 294 ± 9 mOsmol/kg Η2Ο. Daily water intake was higher in summer (2.8 ± 1.02 L) than in winter (2.6 ± 0.98 L) (p = 0.019). Water intake was associated negatively with urine specific gravity, urine color, and urine sodium and potassium concentrations (p < 0.01). Applying urine osmolality cut-offs, approximately 60% of participants were euhydrated and 20% hyperhydrated or dehydrated. Most participants were euhydrated, but a substantial number of people (40%) deviated from a normal hydration level.

  14. Hydrate phase equilibrium and structure for (methane + ethane + tetrahydrofuran + water) system

    International Nuclear Information System (INIS)

    Sun Changyu; Chen Guangjin; Zhang Lingwei

    2010-01-01

    The separation of methane and ethane through forming hydrate is a possible choice in natural gas, oil processing, or ethylene producing. The hydrate formation conditions of five groups of (methane + ethane) binary gas mixtures in the presence of 0.06 mole fraction tetrahydrofuran (THF) in water were obtained at temperatures ranging from (277.7 to 288.2) K. In most cases, the presence of THF in water can lower the hydrate formation pressure of (methane + ethane) remarkably. However, when the composition of ethane is as high as 0.832, it is more difficult to form hydrate than without THF system. Phase equilibrium model for hydrates containing THF was developed based on a two-step hydrate formation mechanism. The structure of hydrates formed from (methane + ethane + THF + water) system was also determined by Raman spectroscopy. When THF concentration in initial aqueous solution was only 0.06 mole fraction, the coexistence of structure I hydrate dominated by ethane and structure II hydrate dominated by THF in the hydrate sample was clearly demonstrated by Raman spectroscopic data. On the contrary, only structure II hydrate existed in the hydrate sample formed from (methane + ethane + THF + water) system when THF concentration in initial aqueous solution was increased to 0.10 mole fraction. It indicated that higher THF concentration inhibited the formation of structure I hydrate dominated by ethane and therefore lowered the trapping of ethane in hydrate. It implies a very promising method to increase the separation efficiency of methane and ethane.

  15. Dietary water affects human skin hydration and biomechanics

    Directory of Open Access Journals (Sweden)

    Palma L

    2015-08-01

    Full Text Available Lídia Palma,1 Liliana Tavares Marques,1 Julia Bujan,2,3 Luís Monteiro Rodrigues1,4 1CBIOS – Research Center for Health Science and Technologies, Universidade Lusófona, Campo Grande, Lisboa, Portugal; 2Department of Medicine and Medical Specialities, Universidad de Alcalá de Henares, Madrid, Spain; 3CIBER-BBN, Madrid, España, Spain; 4Department of Pharmacological Sciences, School of Pharmacy, Universidade de Lisboa, Lisboa, Portugal Abstract: It is generally assumed that dietary water might be beneficial for the health, especially in dermatological (age preventing terms. The present study was designed to quantify the impact of dietary water on major indicators of skin physiology. A total of 49 healthy females (mean 24.5±4.3 years were selected and characterized in terms of their dietary daily habits, especially focused in water consumption, by a Food Frequency Questionnaire. This allowed two groups to be set – Group 1 consuming less than 3,200 mL/day (n=38, and Group 2 consuming more than 3,200 mL/day (n=11. Approximately 2 L of water were added to the daily diet of Group 2 individuals for 1 month to quantify the impact of this surplus in their skin physiology. Measurements involving epidermal superficial and deep hydration, transepidermal water loss, and several biomechanical descriptors were taken at day 0 (T0, 15 (T1, and 30 (T2 in several anatomical sites (face, upper limb, and leg. This stress test (2 L/day for 30 days significantly modified superficial and deep skin hydration, especially in Group 1. The same impact was registered with the most relevant biomechanical descriptors. Thus, in this study, it is clear that higher water inputs in regular diet might positively impact normal skin physiology, in particular in those individuals with lower daily water consumptions. Keywords: dietary water, water consume, skin hydration, TEWL, skin biomechanics

  16. Application of various water soluble polymers in gas hydrate inhibition

    DEFF Research Database (Denmark)

    Kamal, Muhammad Shahzad; Hussein, Ibnelwaleed A.; Sultan, Abdullah S.

    2016-01-01

    . This review presents the various types of water soluble polymers used for hydrate inhibition, including conventional and novel polymeric inhibitors along with their limitations. The review covers the relevant properties of vinyl lactam, amide, dendrimeric, fluorinated, and natural biodegradable polymers....... The factors affecting the performance of these polymers and the structure-property relationships are reviewed. A comprehensive review of the techniques used to evaluate the performance of the polymeric inhibitors is given. This review also addresses recent developments, current and future challenges...

  17. Purification of arsenic contaminated ground water using hydrated manganese dioxide

    International Nuclear Information System (INIS)

    Raje, N.; Swain, K.K.

    2002-01-01

    An analytical methodology has been developed for the separation of arsenic from ground water using inorganic material in neutral medium. The separation procedure involves the quantitative retention of arsenic on hydrated manganese dioxide, in neutral medium. The validity of the separation procedure has been checked by a standard addition method and radiotracer studies. Neutron activation analysis (NAA), a powerful measurement technique, has been used for the quantitative determination of arsenic. (author)

  18. 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).

  19. Dietary water affects human skin hydration and biomechanics.

    Science.gov (United States)

    Palma, Lídia; Marques, Liliana Tavares; Bujan, Julia; Rodrigues, Luís Monteiro

    2015-01-01

    It is generally assumed that dietary water might be beneficial for the health, especially in dermatological (age preventing) terms. The present study was designed to quantify the impact of dietary water on major indicators of skin physiology. A total of 49 healthy females (mean 24.5±4.3 years) were selected and characterized in terms of their dietary daily habits, especially focused in water consumption, by a Food Frequency Questionnaire. This allowed two groups to be set - Group 1 consuming less than 3,200 mL/day (n=38), and Group 2 consuming more than 3,200 mL/day (n=11). Approximately 2 L of water were added to the daily diet of Group 2 individuals for 1 month to quantify the impact of this surplus in their skin physiology. Measurements involving epidermal superficial and deep hydration, transepidermal water loss, and several biomechanical descriptors were taken at day 0 (T0), 15 (T1), and 30 (T2) in several anatomical sites (face, upper limb, and leg). This stress test (2 L/day for 30 days) significantly modified superficial and deep skin hydration, especially in Group 1. The same impact was registered with the most relevant biomechanical descriptors. Thus, in this study, it is clear that higher water inputs in regular diet might positively impact normal skin physiology, in particular in those individuals with lower daily water consumptions.

  20. Neutron emission during lithium deuteride hydration in heavy water

    International Nuclear Information System (INIS)

    Arzhannikov, A.V.; Kezerashvili, G.Ya.; Muratov, V.V.; Sinitskij, S.L.

    1989-01-01

    An experiment on neutron detection during lithium deuteride hydration in heavy water using a system of SNM-17 or SNM-18 gas counters was set up. Signals were simultaneously detected by 6 counters and the data were stored in a computer. At the same time the temperature of the reaction ampule external surface was measured. It was found that the neutron number per 1 gram of lithium deuteride reacted with water in the ampule was equal to several dozens if their initial energy was about 2.5 MeV. 4 refs.; 2 figs

  1. Macroscopic investigation of water volume effects on interfacial dynamic behaviors between clathrate hydrate and water.

    Science.gov (United States)

    Cha, Minjun; Couzis, Alexander; Lee, Jae W

    2013-05-14

    This study investigated the effects of the water volume on the interfacial dynamics between cyclopentane (CP) hydrate and water droplet in a CP/n-decane oil mixture. The adhesion force between CP hydrate and various water droplets was determined using the z-directional microbalance. Through repetition of precise measurements over several cycles from contact to detachment, we observed abnormal wetting behaviors in the capillary bridge during the retraction process when the water drop volume is larger than 100 μL. With the increase in water droplet volumes, the contact force between CP hydrate and water also increases up to 300 μL. However, there is a dramatic reduction of increasing rate in the contact forces over 300 μL of water droplet. With the addition of the surfactants of sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) to the water droplet, the contact force between CP hydrate and solution droplet exhibits a lower value and a transition volume of the contact force comes with a smaller solution volume of 200 μL. The water volume effects on the liquid wetting of the probe and the size of capillary bridges provide important insight into hydrate growth and aggregation/agglomeration in the presence of free water phase inside gas/oil pipelines.

  2. Topological modeling of methane hydrate crystallization from low to high water cut emulsion systems

    OpenAIRE

    Melchuna , Aline; Cameirão , Ana; Herri , Jean-Michel; Glénat , Philippe

    2016-01-01

    International audience; Hydrate formation and remediation in oil flowlines facilities represent a major concern for oil industry in respect of capital and operational costs. It is necessary to have a better understanding on the hydrate formation process to be more efficient in hydrate prevention, especially in respect to additive dosage. This work is a contribution to enhance the knowledge of hydrate formation at high water cuts, by introducing new techniques of analysis in the Archimede flow...

  3. Visual observation of gas hydrates nucleation and growth at a water - organic liquid interface

    Science.gov (United States)

    Stoporev, Andrey S.; Semenov, Anton P.; Medvedev, Vladimir I.; Sizikov, Artem A.; Gushchin, Pavel A.; Vinokurov, Vladimir A.; Manakov, Andrey Yu.

    2018-03-01

    Visual observation of nucleation sites of methane and methane-ethane-propane hydrates and their further growth in water - organic liquid - gas systems with/without surfactants was carried out. Sapphire Rocking Cell RCS6 with transparent sapphire cells was used. The experiments were conducted at the supercooling ΔTsub = 20.2 °C. Decane, toluene and crude oils were used as organics. Gas hydrate nucleation occurred on water - metal - gas and water - sapphire - organic liquid three-phase contact lines. At the initial stage of growth hydrate crystals rapidly covered the water - gas or water - organics interfaces (depending on the nucleation site). Further hydrate phase accrete on cell walls (sapphire surface) and into the organics volume. At this stage, growth was accompanied by water «drawing out» from under initial hydrate film formed at water - organic interface. Apparently, it takes place due to water capillary inflow in the reaction zone. It was shown that the hydrate crystal morphology depends on the organic phase composition. In the case of water-in-decane emulsion relay hydrate crystallization was observed in the whole sample, originating most likely due to the hydrate crystal intergrowth through decane. Contacts of such crystals with adjacent water droplets result in rapid hydrate crystallization on this droplet.

  4. Influence of surfactants on gas-hydrate formation' kinetics in water-oil emulsion

    Science.gov (United States)

    Zemenkov, Yu D.; Shirshova, A. V.; Arinstein, E. A.; Shuvaev, A. N.

    2018-05-01

    The kinetics of gas hydrate formation of propane in a water-oil emulsion is experimentally studied when three types of surfactants (SAA (surface acting agent)) - anionic type emulsifiers - are added to the aqueous phase. It is shown that all three types of surfactants decelerate the growth of the gas-hydrate in the emulsion and can be considered as anti-agglutinating and kinetic low-dose inhibitors. The most effective inhibitor of hydrate formation in water-oil emulsion of SV-102 surfactant was revealed. For comparison, experimental studies of gas-hydrate formation under the same conditions for bulk water have been carried out. It is shown that in bulk water, all the surfactants investigated act as promoters (accelerators) of hydrate formation. A qualitative explanation of the action mechanisms of emulsifiers in the process of gas-hydrate formation in water-oil emulsion is given.

  5. Numerical analysis of wellbore instability in gas hydrate formation during deep-water drilling

    Science.gov (United States)

    Zhang, Huaiwen; Cheng, Yuanfang; Li, Qingchao; Yan, Chuanliang; Han, Xiuting

    2018-02-01

    Gas hydrate formation may be encountered during deep-water drilling because of the large amount and wide distribution of gas hydrates under the shallow seabed of the South China Sea. Hydrates are extremely sensitive to temperature and pressure changes, and drilling through gas hydrate formation may cause dissociation of hydrates, accompanied by changes in wellbore temperatures, pore pressures, and stress states, thereby leading to wellbore plastic yield and wellbore instability. Considering the coupling effect of seepage of drilling fluid into gas hydrate formation, heat conduction between drilling fluid and formation, hydrate dissociation, and transformation of the formation framework, this study established a multi-field coupling mathematical model of the wellbore in the hydrate formation. Furthermore, the influences of drilling fluid temperatures, densities, and soaking time on the instability of hydrate formation were calculated and analyzed. Results show that the greater the temperature difference between the drilling fluid and hydrate formation is, the faster the hydrate dissociates, the wider the plastic dissociation range is, and the greater the failure width becomes. When the temperature difference is greater than 7°C, the maximum rate of plastic deformation around the wellbore is more than 10%, which is along the direction of the minimum horizontal in-situ stress and associated with instability and damage on the surrounding rock. The hydrate dissociation is insensitive to the variation of drilling fluid density, thereby implying that the change of the density of drilling fluids has a minimal effect on the hydrate dissociation. Drilling fluids that are absorbed into the hydrate formation result in fast dissociation at the initial stage. As time elapses, the hydrate dissociation slows down, but the risk of wellbore instability is aggravated due to the prolonged submersion in drilling fluids. For the sake of the stability of the wellbore in deep-water

  6. Collective dynamics of protein hydration water by brillouin neutron spectroscopy.

    Science.gov (United States)

    Orecchini, Andrea; Paciaroni, Alessandro; De Francesco, Alessio; Petrillo, Caterina; Sacchetti, Francesco

    2009-04-08

    By a detailed experimental study of THz dynamics in the ribonuclease protein, we could detect the propagation of coherent collective density fluctuations within the protein hydration shell. The emerging picture indicates the presence of both a dispersing mode, traveling with a speed greater than 3000 m/s, and a nondispersing one, characterized by an almost constant energy of 6-7 meV. In agreement with molecular dynamics simulations [Phys. Rev. Lett. 2002, 89, 275501], the features of the dispersion curves closely resemble those observed in pure liquid water [Phys. Rev. E: Stat. Phys., Plasmas, Fluids, Relat. Interdiscip. Top. 2004, 69, 061203]. On the contrary, the observed damping factors are much larger than in bulk water, with the dispersing mode becoming overdamped at Q = 0.6 A(-1) already. Such novel experimental findings are discussed as a dynamic signature of the disordering effect induced by the protein surface on the local structure of water.

  7. Hydration dynamics in water clusters via quantum molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Turi, László, E-mail: turi@chem.elte.hu [Department of Physical Chemistry, Eötvös Loránd University, Budapest 112, P. O. Box 32, H-1518 (Hungary)

    2014-05-28

    We have investigated the hydration dynamics in size selected water clusters with n = 66, 104, 200, 500, and 1000 water molecules using molecular dynamics simulations. To study the most fundamental aspects of relaxation phenomena in clusters, we choose one of the simplest, still realistic, quantum mechanically treated test solute, an excess electron. The project focuses on the time evolution of the clusters following two processes, electron attachment to neutral equilibrated water clusters and electron detachment from an equilibrated water cluster anion. The relaxation dynamics is significantly different in the two processes, most notably restoring the equilibrium final state is less effective after electron attachment. Nevertheless, in both scenarios only minor cluster size dependence is observed. Significantly different relaxation patterns characterize electron detachment for interior and surface state clusters, interior state clusters relaxing significantly faster. This observation may indicate a potential way to distinguish surface state and interior state water cluster anion isomers experimentally. A comparison of equilibrium and non-equilibrium trajectories suggests that linear response theory breaks down for electron attachment at 200 K, but the results converge to reasonable agreement at higher temperatures. Relaxation following electron detachment clearly belongs to the linear regime. Cluster relaxation was also investigated using two different computational models, one preferring cavity type interior states for the excess electron in bulk water, while the other simulating non-cavity structure. While the cavity model predicts appearance of several different hydrated electron isomers in agreement with experiment, the non-cavity model locates only cluster anions with interior excess electron distribution. The present simulations show that surface isomers computed with the cavity predicting potential show similar dynamical behavior to the interior clusters of

  8. Desalination of Produced Water via Gas Hydrate Formation and Post Treatment

    OpenAIRE

    Niu, Jing

    2012-01-01

    This study presents a two-step desalination process, in which produced water is cleaned by forming gas hydrate in it and subsequently dewatering the hydrate to remove the residual produced water trapped in between the hydrate crystals. All experiments were performed with pressure in the range of 450 to 800psi and temperature in the range of -1 to 1°C using CO? as guest molecule for the hydrate crystals. The experiments were conducted using artificial produced waters containing different amoun...

  9. Dynamic morphology of gas hydrate on a methane bubble in water: Observations and new insights for hydrate film models

    Science.gov (United States)

    Warzinski, Robert P.; Lynn, Ronald; Haljasmaa, Igor; Leifer, Ira; Shaffer, Frank; Anderson, Brian J.; Levine, Jonathan S.

    2014-10-01

    Predicting the fate of subsea hydrocarbon gases escaping into seawater is complicated by potential formation of hydrate on rising bubbles that can enhance their survival in the water column, allowing gas to reach shallower depths and the atmosphere. The precise nature and influence of hydrate coatings on bubble hydrodynamics and dissolution is largely unknown. Here we present high-definition, experimental observations of complex surficial mechanisms governing methane bubble hydrate formation and dissociation during transit of a simulated oceanic water column that reveal a temporal progression of deep-sea controlling mechanisms. Synergistic feedbacks between bubble hydrodynamics, hydrate morphology, and coverage characteristics were discovered. Morphological changes on the bubble surface appear analogous to macroscale, sea ice processes, presenting new mechanistic insights. An inverse linear relationship between hydrate coverage and bubble dissolution rate is indicated. Understanding and incorporating these phenomena into bubble and bubble plume models will be necessary to accurately predict global greenhouse gas budgets for warming ocean scenarios and hydrocarbon transport from anthropogenic or natural deep-sea eruptions.

  10. Modelling membrane hydration and water balance of a pem fuel cell

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh

    2015-01-01

    Polymer electrolyte membrane (PEM) fuel cells requires an appropriate hydration in order to ensure high efficiency and long durability. As water is essential for promoting proton conductivity in the membrane, it is important to control membrane water hydration to avoid flooding. In this study we...

  11. Water Transfer Characteristics during Methane Hydrate Formation Processes in Layered Media

    Directory of Open Access Journals (Sweden)

    Yousheng Deng

    2011-08-01

    Full Text Available Gas hydrate formation processes in porous media are always accompanied by water transfer. To study the transfer characteristics comprehensively, two kinds of layered media consisting of coarse sand and loess were used to form methane hydrate in them. An apparatus with three PF-meter sensors detecting water content and temperature changes in media during the formation processes was applied to study the water transfer characteristics. It was experimentally observed that the hydrate formation configurations in different layered media were similar; however, the water transfer characteristics and water conversion ratios were different.

  12. Study of the Effects of Betaine and/or C-Phycocyanin on the Growth of Lung Cancer A549 Cells In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    Rea Bingula

    2016-01-01

    Full Text Available We investigated the effects of betaine, C-phycocyanin (C-PC, and their combined use on the growth of A549 lung cancer both in vitro and in vivo. When cells were coincubated with betaine and C-PC, an up to 60% decrease in viability was observed which is significant compared to betaine (50% or C-PC treatment alone (no decrease. Combined treatment reduced the stimulation of NF-κB expression by TNF-α and increased the amount of the proapoptotic p38 MAPK. Interestingly, combined treatment induced a cell cycle arrest in G2/M phase for ~60% of cells. In vivo studies were performed in pathogen-free male nude rats injected with A549 cells in their right flank. Their daily food was supplemented with either betaine, C-PC, both, or neither. Compared to the control group, tumour weights and volumes were significantly reduced in either betaine- or C-PC-treated groups and no additional decrease was obtained with the combined treatment. This data indicates that C-PC and betaine alone may efficiently inhibit tumour growth in rats. The synergistic activity of betaine and C-PC on A549 cells growth observed in vitro remains to be further confirmed in vivo. The reason behind the nature of their interaction is yet to be sought.

  13. Higher production of C-phycocyanin by nitrogen-free (diazotrophic) cultivation of Nostoc sp. NK and simplified extraction by dark-cold shock.

    Science.gov (United States)

    Lee, Na Kyeong; Oh, Hee-Mock; Kim, Hee-Sik; Ahn, Chi-Yong

    2017-03-01

    Nostoc sp. NK (KCTC 12772BP) was isolated and cultivated in a BG11 medium and a nitrate-free BG11 medium (BG11 0 ). To enhance C-phycocyanin (C-PC) content in the cells, different fluorescent lamps (white, plant, and red) were used as light sources for complementary chromatic adaptation (CCA). The maximum biomass productivity was 0.42g/L/d and 0.32g/L/d under BG11 and BG11 0 conditions, respectively. The maximum C-PC contents were 8.4% (w/w) under white lamps, 13.6% (w/w) under plant lamps, and 18% (w/w) under BG11 0 and the red light condition. The maximum C-PC productivity was 57.4mg/L/d in BG11 0 under the red lamp condition. These results indicate that a higher C-PC content could be obtained under a diazotrophic condition and a CCA reaction. The C-PC could be released naturally from cells without any extraction processes, when Nostoc sp. NK was cultivated in the BG11 0 medium with CO 2 aeration and put in dark conditions at 5°C. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Measurements of gas permeability and non-Darcy flow in gas-water-hydrate systems

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

    Storage of carbon dioxide (CO{sub 2}) in natural gas hydrate reservoirs may offer stable long-term storage of a greenhouse gas while benefiting from methane production, without requiring heat. By exposing hydrate to a thermodynamically preferred hydrate former, CO{sub 2}, the hydrate may be maintained macroscopically in the solid state and retain the stability of the formation. However, there is concern over the flow capacity in such reservoirs. This depends on several factors, notably thermodynamic destabilization of hydrate in small pores due to capillary effects; the presence of liquid channels separating the hydrate from the mineral surfaces; and, the connectivity of gas or liquid filled pores and channels. This paper described a technique for measuring gas permeability in gas-water-hydrate systems. It reported on several experiments that measured gas permeability during stages of hydrate growth in sandstone core plugs. Interactions between minerals and surrounding molecules were also discussed. The formation of methane hydrate in porous media was monitored and quantified with magnetic resonance imaging (MRI). MRI images of hydrate growth within the porous rock were provided along with measurements of gas permeability and non-Darcy flow effects at various hydrate saturations. Gas permeability was measured at steady state flow of methane through the hydrate-bearing core sample. Significant gas permeability was recorded for porous sandstone even when hydrates occupied up to 60 per cent of the pore space. It was concluded that MRI imaging can be used effectively to map and quantify hydrate saturation in sandstone core plugs. 27 refs., 2 tabs., 10 figs.

  15. Water Dynamics in Protein Hydration Shells: The Molecular Origins of the Dynamical Perturbation

    Science.gov (United States)

    2014-01-01

    Protein hydration shell dynamics play an important role in biochemical processes including protein folding, enzyme function, and molecular recognition. We present here a comparison of the reorientation dynamics of individual water molecules within the hydration shell of a series of globular proteins: acetylcholinesterase, subtilisin Carlsberg, lysozyme, and ubiquitin. Molecular dynamics simulations and analytical models are used to access site-resolved information on hydration shell dynamics and to elucidate the molecular origins of the dynamical perturbation of hydration shell water relative to bulk water. We show that all four proteins have very similar hydration shell dynamics, despite their wide range of sizes and functions, and differing secondary structures. We demonstrate that this arises from the similar local surface topology and surface chemical composition of the four proteins, and that such local factors alone are sufficient to rationalize the hydration shell dynamics. We propose that these conclusions can be generalized to a wide range of globular proteins. We also show that protein conformational fluctuations induce a dynamical heterogeneity within the hydration layer. We finally address the effect of confinement on hydration shell dynamics via a site-resolved analysis and connect our results to experiments via the calculation of two-dimensional infrared spectra. PMID:24479585

  16. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes

    KAUST Repository

    Martinez, N.

    2016-09-06

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure.

  17. High protein flexibility and reduced hydration water dynamics are key pressure adaptive strategies in prokaryotes

    KAUST Repository

    Martinez, N.; Michoud, Gregoire; Cario, A.; Ollivier, J.; Franzetti, B.; Jebbar, M.; Oger, P.; Peters, J.

    2016-01-01

    Water and protein dynamics on a nanometer scale were measured by quasi-elastic neutron scattering in the piezophile archaeon Thermococcus barophilus and the closely related pressure-sensitive Thermococcus kodakarensis, at 0.1 and 40 MPa. We show that cells of the pressure sensitive organism exhibit higher intrinsic stability. Both the hydration water dynamics and the fast protein and lipid dynamics are reduced under pressure. In contrast, the proteome of T. barophilus is more pressure sensitive than that of T. kodakarensis. The diffusion coefficient of hydration water is reduced, while the fast protein and lipid dynamics are slightly enhanced with increasing pressure. These findings show that the coupling between hydration water and cellular constituents might not be simply a master-slave relationship. We propose that the high flexibility of the T. barophilus proteome associated with reduced hydration water may be the keys to the molecular adaptation of the cells to high hydrostatic pressure.

  18. 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.

  19. Hydrophobic hydration and the anomalous partial molar volumes in ethanol-water mixtures

    International Nuclear Information System (INIS)

    Tan, Ming-Liang; Te, Jerez; Cendagorta, Joseph R.; Miller, Benjamin T.; Brooks, Bernard R.; Ichiye, Toshiko

    2015-01-01

    The anomalous behavior in the partial molar volumes of ethanol-water mixtures at low concentrations of ethanol is studied using molecular dynamics simulations. Previous work indicates that the striking minimum in the partial molar volume of ethanol V E as a function of ethanol mole fraction X E is determined mainly by water-water interactions. These results were based on simulations that used one water model for the solute-water interactions but two different water models for the water-water interactions. This is confirmed here by using two more water models for the water-water interactions. Furthermore, the previous work indicates that the initial decrease is caused by association of the hydration shells of the hydrocarbon tails, and the minimum occurs at the concentration where all of the hydration shells are touching each other. Thus, the characteristics of the hydration of the tail that cause the decrease and the features of the water models that reproduce this type of hydration are also examined here. The results show that a single-site multipole water model with a charge distribution that mimics the large quadrupole and the p-orbital type electron density out of the molecular plane has “brittle” hydration with hydrogen bonds that break as the tails touch, which reproduces the deep minimum. However, water models with more typical site representations with partial charges lead to flexible hydration that tends to stay intact, which produces a shallow minimum. Thus, brittle hydration may play an essential role in hydrophobic association in water

  20. The Dependence of Water Permeability in Quartz Sand on Gas Hydrate Saturation in the Pore Space

    Science.gov (United States)

    Kossel, E.; Deusner, C.; Bigalke, N.; Haeckel, M.

    2018-02-01

    Transport of fluids in gas hydrate bearing sediments is largely defined by the reduction of the permeability due to gas hydrate crystals in the pore space. Although the exact knowledge of the permeability behavior as a function of gas hydrate saturation is of crucial importance, state-of-the-art simulation codes for gas production scenarios use theoretically derived permeability equations that are hardly backed by experimental data. The reason for the insufficient validation of the model equations is the difficulty to create gas hydrate bearing sediments that have undergone formation mechanisms equivalent to the natural process and that have well-defined gas hydrate saturations. We formed methane hydrates in quartz sand from a methane-saturated aqueous solution and used magnetic resonance imaging to obtain time-resolved, three-dimensional maps of the gas hydrate saturation distribution. These maps were fed into 3-D finite element method simulations of the water flow. In our simulations, we tested the five most well-known permeability equations. All of the suitable permeability equations include the term (1-SH)n, where SH is the gas hydrate saturation and n is a parameter that needs to be constrained. The most basic equation describing the permeability behavior of water flow through gas hydrate bearing sand is k = k0 (1-SH)n. In our experiments, n was determined to be 11.4 (±0.3). Results from this study can be directly applied to bulk flow analysis under the assumption of homogeneous gas hydrate saturation and can be further used to derive effective permeability models for heterogeneous gas hydrate distributions at different scales.

  1. α-chymotrypsin in water-acetone and water-dimethyl sulfoxide mixtures: Effect of preferential solvation and hydration.

    Science.gov (United States)

    Sirotkin, Vladimir A; Kuchierskaya, Alexandra A

    2017-10-01

    We investigated water/organic solvent sorption and residual enzyme activity to simultaneously monitor preferential solvation/hydration of protein macromolecules in the entire range of water content at 25°C. We applied this approach to estimate protein destabilization/stabilization due to the preferential interactions of bovine pancreatic α-chymotrypsin with water-acetone (moderate-strength H-bond acceptor) and water-DMSO (strong H-bond acceptor) mixtures. There are three concentration regimes for the dried α-chymotrypsin. α-Chymotrypsin is preferentially hydrated at high water content. The residual enzyme activity values are close to 100%. At intermediate water content, the dehydrated α-chymotrypsin has a higher affinity for acetone/DMSO than for water. Residual enzyme activity is minimal in this concentration range. The acetone/DMSO molecules are preferentially excluded from the protein surface at the lowest water content, resulting in preferential hydration. The residual catalytic activity in the water-poor acetone is ∼80%, compared with that observed after incubation in pure water. This effect is very small for the water-poor DMSO. Two different schemes are operative for the hydrated enzyme. At high and intermediate water content, α-chymotrypsin exhibits preferential hydration. However, at intermediate water content, in contrast to the dried enzyme, the initially hydrated α-chymotrypsin possesses increased preferential hydration parameters. At low water content, no residual enzyme activity was observed. Preferential binding of DMSO/acetone to α-chymotrypsin was detected. Our data clearly demonstrate that the hydrogen bond accepting ability of organic solvents and the protein hydration level constitute key factors in determining the stability of protein-water-organic solvent systems. © 2017 Wiley Periodicals, Inc.

  2. Hydration kinetics of cement composites with varying water-cement ratio using terahertz spectroscopy

    Science.gov (United States)

    Ray, Shaumik; Dash, Jyotirmayee; Devi, Nirmala; Sasmal, Saptarshi; Pesala, Bala

    2015-03-01

    Cement is mixed with water in an optimum ratio to form concrete with desirable mechanical strength and durability. The ability to track the consumption of major cement constituents, viz., Tri- and Dicalcium Silicates (C3S, C2S) reacting with water along with the formation of key hydration products, viz., Calcium-Silicate-Hydrate (C-S-H) which gives the overall strength to the concrete and Calcium Hydroxide (Ca(OH)2), a hydration product which reduces the strength and durability, using an efficient technique is highly desirable. Optimizing the amount of water to be mixed with cement is one of the main parameters which determine the strength of concrete. In this work, THz spectroscopy has been employed to track the variation in hydration kinetics for concrete samples with different water-cement ratios, viz., 0.3, 0.4, 0.5 and 0.6. Results show that for the sample with water-cement ratio of 0.3, significant amount of the C3S and C2S remain unreacted even after the initial hydration period of 28 days while for the cement with water-cement ratio of 0.6, most of the constituents get consumed during this stage. Analysis of the formation of Ca(OH)2 has been done which shows that the concrete sample with water-cement ratio of 0.6 produces the highest amount of Ca(OH)2 due to higher consumption of C3S/C2S in presence of excess water which is not desirable. Samples with water-cement ratio of 0.4 and 0.5 show more controlled reaction during the hydration which can imply formation of an optimized level of desired hydration products resulting in a more mechanically strong and durable concrete.

  3. Fractionation of hydrogen and oxygen isotopes between hydrated and free water molecules in aqueous urea solution

    International Nuclear Information System (INIS)

    Kakiuchi, M.; Matsuo, S.

    1985-01-01

    Ratios of D/H and 18 O/ 16 O in the vapor phase in equilibrium with aqueous urea solution with different urea molalities were measured at 15 and 25 0 C. Under the assumption that urea solutions consist of two species, i.e., the urea-water cluster and free water, the results are interpreted to give the average hydration number, i.e., the number of water molecules per urea molecule in the urea-water cluster. Good agreement was obtained for the hydration number estimated independently from hydrogen and oxygen isotopic fractions. On the basis of hydrogen isotopic data at 25 0 C, the average hydration number of urea in the cluster is 6.3 +/- 0.8 at 2.1 m and 2.75 +/- 0.08 at saturation (20.15 m). The corresponding average hydration numbers based on oxygen isotopic data were calculated to be 6.7 +/- 2.4 at 2.1 m and 2.75 +/- 0.25 at urea saturation. HD 16 O is enriched in the urea-water cluster and H 2 18 O is enriched in free water. Isotopic partitioning between the cluster and free water is markedly different from those between hydration spheres and free water in aqueous electrolyte solutions. 29 references, 6 figures, 5 tables

  4. Adsorption of water and carbon dioxide on hematite and consequences for possible hydrate formation.

    Science.gov (United States)

    Kvamme, Bjørn; Kuznetsova, Tatiana; Kivelae, Pilvi-Helina

    2012-04-07

    The interest in carbon dioxide for enhanced oil recovery is increasing proportional to the decline in naturally driven oil production and also due to the increasing demand for reduced emission of carbon dioxide into the atmosphere. Transport of carbon dioxide in offshore pipelines involves high pressure and low temperatures, conditions which may lead to formation of hydrates from residual water dissolved in carbon dioxide and carbon dioxide. The critical question is whether the water at certain temperatures and pressures will drop out as liquid droplets first, and then form hydrates, or alternatively, adsorb on the pipeline surfaces, and subsequently form hydrates heterogeneously. In this work, we used several different basis sets of density functional theory in ab initio calculations to estimate the charge distribution of hematite (the dominating component of rust) crystals. These rust particles were embedded in water and chemical potential for adsorbed water molecules was estimated through thermodynamic integration and compared to similar estimates for water clusters of the same size. While the generated charges were not unique, the use of high order approximations and different basis sets provides a range of likely charge distributions. Values obtained for the chemical potential of water in different surroundings indicated that it would be thermodynamically favorable for water to adsorb on hematite, and that evaluation of potential carbon dioxide hydrate formation conditions and kinetics should be based on this formation mechanism. Depending on the basis set and approximations, the estimated gain for water to adsorb on the hematite surface rather than condense as droplets varied between -1.7 kJ mole(-1) and -3.4 kJ mole(-1). The partial charge distribution on the hematite surface is incompatible with the hydrate structure, and thus hydrates will be unable to attach to the surface. The behavior of water outside the immediate vicinity of hematite (beyond 3

  5. Experimental flowloop study on methane hydrate formation and agglomeration in high water cut emulsion systems

    OpenAIRE

    Pham , Trung-Kien; Cameirao , Ana ,; Herri , Jean-Michel

    2016-01-01

    Thème de cette communication: International Conference on Integrated Petroleum Engineering (IPE); International audience; hydrate risk also increases. Especially in the offshore systems, operating at low temperature and high pressure, conditions are favourable to the formation of gas hydrate, from the combination of liquid water and gas molecules, under the form of a solid phase. It is a serious issue in the flow assurance; it may cause many troubles, up to plugging.This work brings new under...

  6. Modelling a deep water oil/gas spill under conditions of gas hydrate formation and decomposition

    International Nuclear Information System (INIS)

    Zheng, L.; Yapa, P.D.

    2000-01-01

    A model for the behavior of oil and gas spills at deepwater locations was presented. Such spills are subjected to pressures and temperatures that can convert gases to gas hydrates which are lighter than water. Knowing the state of gases as they rise with the plume is important in predicting the fate of an oil or gas plume released in deepwater. The objective of this paper was to develop a comprehensive jet/plume model which includes computational modules that simulate the gas hydrate formation/decomposition of gas bubbles. This newly developed model is based on the kinetics of hydrate formation and decomposition coupled with mass and heat transfer phenomena. The numerical model was successfully tested using results of experimental data from the Gulf of Mexico. Hydrate formation and decomposition are integrated with an earlier model by Yapa and Zheng for underwater oil or gas jets and plumes. The effects of hydrate on the behavior of an oil or gas plume was simulated to demonstrate the models capabilities. The model results indicate that in addition to thermodynamics, the kinetics of hydrate formation/decomposition should be considered when studying the behavior of oil and gas spills. It was shown that plume behavior changes significantly depending on whether or not the local conditions force the gases to form hydrates. 25 refs., 4 tabs., 12 figs

  7. Hydration measured by doubly labeled water in ALS and its effects on survival.

    Science.gov (United States)

    Scagnelli, Connor N; Howard, Diantha B; Bromberg, Mark B; Kasarskis, Edward J; Matthews, Dwight E; Mitsumoto, Hiroshi M; Simmons, Zachary; Tandan, Rup

    2018-05-01

    We present a study of hydration in ALS patients and its effects on survival. This was a multicenter study over 48 weeks in 80 ALS patients who underwent 250 individual measurements using doubly labeled water (DLW). Total body water (TBW) and water turnover (a surrogate for water intake) were 3.4% and 8.6% lower, respectively, in patients compared to age- and gender-matched healthy controls, and both significantly decreased over study duration. In 20% of patients, water turnover measured over 10 d was 2 standard deviations below the mean value in healthy controls. In a separate clinic cohort of 208 patients, water intake estimated from a de novo equation created from common clinical endpoints was a prognostic indicator of survival. Regardless of nutritional state assessed by BMI, survival was two-fold longer in the group above the median for estimated water intake, suggesting that hydration may be a more important predictor of survival than malnutrition. Risk factors for poor hydration were identified. Water intake equations recommended by US Centers for Medicare and Medicaid Services in healthy elderly were inaccurate for use in ALS patients. We developed equations to estimate TBW and water intake in ALS patients for use in clinics to accurately estimate hydration and improve clinical care.

  8. 1H NMR relaxometry as an indicator of setting and water depletion during cement hydration

    International Nuclear Information System (INIS)

    Wang, Biyun; Faure, Paméla; Thiéry, Mickaël; Baroghel-Bouny, Véronique

    2013-01-01

    Proton nuclear magnetic resonance relaxometry has been used to detect setting and microstructure evolution during cement hydration. NMR measurements were performed since casting, during setting and until hardening (from 0 to 3 days). The mobility of water molecules was assessed by an analysis focused on the diagram of longitudinal relaxation time T 1 generated by an Inversion Recovery sequence. The initial stiffening of the solid network was identified by an analysis of the relaxation rate 1/T 1 . The kinetics of water depletion was investigated by using a simple one-pulse acquisition sequence. In parallel, conventional techniques (Vicat needle and temperature monitoring), as well as numerical simulations of hydration, were used to complement and validate these NMR results. Cement pastes and mortars with different water-to-cement ratios made of grey or white OPCs were tested. Furthermore, the effects of the addition of sand, super-plasticizer and silica fume on the hydration kinetics were investigated

  9. Description of gas hydrates equilibria in sediments using experimental data of soil water potential

    Energy Technology Data Exchange (ETDEWEB)

    Istomin, V. [NOVATEK, Moscow (Russian Federation); Chuvilin, E. [Moscow State Univ., Moscow (Russian Federation). Dept. of Geology; Makhonina, N.; Kvon, V. [VNIIGAZ, Moscow (Russian Federation); Safonov, S. [Schlumberger Moscow Research, Moscow (Russian Federation)

    2008-07-01

    Analytical relationships have been developed between hydrate dissociation pressure and vapor pressure above the pore water surface. In addition, experiments have been discussed in numerous publications on the effect of narrow interconnected throats between pores on clathrate dissociation conditions in porous media. This paper presented an approach that improved upon the available thermodynamic methods for calculation of hydrate phase equilibria. The approach took into account the properties of pore water in natural sediments including three-phase equilibrium of gas-pore water-gas hydrate in a similar way as for unfrozen water in geocryology science. The purpose of the paper was to apply and adapt geocryology and soil physics method to the thermodynamic calculation of non-clathrated water content in sediments. It answered the question of how to estimate the non-clathrated water content if pore water potential was known. The paper explained the thermodynamics of water phase in porous media including the thermodynamic properties of supercooled water, the thermodynamic properties of pore water and pore ice in sediments, and the phase equilibria of pore water. The paper also discussed the quantitative techniques that were utilized for determination of unfrozen water content in sediments and its dependence on temperature variation. These included contact-saturation, calorimetric, dielectric, nuclear magnetic resonance, and others. The thermodynamic calculations of pore water phase equilibria were also presented. 30 refs., 5 tabs., 8 figs.

  10. In silico studies of the properties of water hydrating a small protein

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Sudipta Kumar; Chakraborty, Kausik; Bandyopadhyay, Sanjoy, E-mail: sanjoy@chem.iitkgp.ernet.in [Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur - 721302 (India); Jana, Madhurima [Molecular Simulation Laboratory, Department of Chemistry, National Institute of Technology, Rourkela - 769008 (India)

    2014-12-14

    Atomistic molecular dynamics simulation of an aqueous solution of the small protein HP-36 has been carried out with explicit solvent at room temperature. Efforts have been made to explore the influence of the protein on the relative packing and ordering of water molecules around its secondary structures, namely, three α-helices. The calculations reveal that the inhomogeneous water ordering and density distributions around the helices are correlated with their relative hydrophobicity. Importantly, we have identified the existence of a narrow relatively dehydrated region containing randomly organized “quasi-free” water molecules beyond the first layer of “bound” waters at the protein surface. These water molecules with relatively weaker binding energies form the transition state separating the “bound” and “free” water molecules at the interface. Further, increased contribution of solid-like caging motions of water molecules around the protein is found to be responsible for reduced fluidity of the hydration layer. Interestingly, we notice that the hydration layer of helix-3 is more fluidic with relatively higher entropy as compared to the hydration layers of the other two helical segments. Such characteristics of helix-3 hydration layer correlate well with the activity of HP-36, as helix-3 contains the active site of the protein.

  11. In silico studies of the properties of water hydrating a small protein

    International Nuclear Information System (INIS)

    Sinha, Sudipta Kumar; Chakraborty, Kausik; Bandyopadhyay, Sanjoy; Jana, Madhurima

    2014-01-01

    Atomistic molecular dynamics simulation of an aqueous solution of the small protein HP-36 has been carried out with explicit solvent at room temperature. Efforts have been made to explore the influence of the protein on the relative packing and ordering of water molecules around its secondary structures, namely, three α-helices. The calculations reveal that the inhomogeneous water ordering and density distributions around the helices are correlated with their relative hydrophobicity. Importantly, we have identified the existence of a narrow relatively dehydrated region containing randomly organized “quasi-free” water molecules beyond the first layer of “bound” waters at the protein surface. These water molecules with relatively weaker binding energies form the transition state separating the “bound” and “free” water molecules at the interface. Further, increased contribution of solid-like caging motions of water molecules around the protein is found to be responsible for reduced fluidity of the hydration layer. Interestingly, we notice that the hydration layer of helix-3 is more fluidic with relatively higher entropy as compared to the hydration layers of the other two helical segments. Such characteristics of helix-3 hydration layer correlate well with the activity of HP-36, as helix-3 contains the active site of the protein

  12. Squirt flow due to interfacial water films in hydrate bearing sediments

    Directory of Open Access Journals (Sweden)

    K. Sell

    2018-05-01

    Full Text Available Sediments containing gas hydrate dispersed in the pore space are known to show a characteristic seismic anomaly which is a high attenuation along with increasing seismic velocities. Currently, this observation cannot be fully explained albeit squirt-flow type mechanisms on the microscale have been speculated to be the cause. Recent major findings from in situ experiments, using the gas in excess and water in excess formation method, and coupled with high-resolution synchrotron-based X-ray micro-tomography, have revealed the systematic presence of thin water films between the quartz grains and the encrusting hydrate. The data obtained from these experiments underwent an image processing procedure to quantify the thicknesses and geometries of the aforementioned interfacial water films. Overall, the water films vary from sub-micrometer to a few micrometers in thickness. In addition, some of the water films interconnect through water bridges. This geometrical analysis is used to propose a new conceptual squirt flow model for hydrate bearing sediments. A series of numerical simulations is performed considering variations of the proposed model to study seismic attenuation caused by such thin water films. Our results support previous speculation that squirt flow can explain high attenuation at seismic frequencies in hydrate bearing sediments, but based on a conceptual squirt flow model which is geometrically different than those previously considered.

  13. Dual reorientation relaxation routes of water molecules in oxyanion’s hydration shell: A molecular geometry perspective

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Wen Jun; Yang, Yi Isaac; Gao, Yi Qin, E-mail: gaoyq@pku.edu.cn [Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering and Biodynamic Optical Imaging Center, Peking University, Beijing 100871 (China)

    2015-12-14

    In this study, we examine how complex ions such as oxyanions influence the dynamic properties of water and whether differences exist between simple halide anions and oxyanions. Nitrate anion is taken as an example to investigate the hydration properties of oxyanions. Reorientation relaxation of its hydration water can occur through two different routes: water can either break its hydrogen bond with the nitrate to form one with another water or switch between two oxygen atoms of the same nitrate. The latter molecular mechanism increases the residence time of oxyanion’s hydration water and thus nitrate anion slows down the translational motion of neighbouring water. But it is also a “structure breaker” in that it accelerates the reorientation relaxation of hydration water. Such a result illustrates that differences do exist between the hydration of oxyanions and simple halide anions as a result of different molecular geometries. Furthermore, the rotation of the nitrate solute is coupled with the hydrogen bond rearrangement of its hydration water. The nitrate anion can either tilt along the axis perpendicularly to the plane or rotate in the plane. We find that the two reorientation relaxation routes of the hydration water lead to different relaxation dynamics in each of the two above movements of the nitrate solute. The current study suggests that molecular geometry could play an important role in solute hydration and dynamics.

  14. Dual reorientation relaxation routes of water molecules in oxyanion’s hydration shell: A molecular geometry perspective

    International Nuclear Information System (INIS)

    Xie, Wen Jun; Yang, Yi Isaac; Gao, Yi Qin

    2015-01-01

    In this study, we examine how complex ions such as oxyanions influence the dynamic properties of water and whether differences exist between simple halide anions and oxyanions. Nitrate anion is taken as an example to investigate the hydration properties of oxyanions. Reorientation relaxation of its hydration water can occur through two different routes: water can either break its hydrogen bond with the nitrate to form one with another water or switch between two oxygen atoms of the same nitrate. The latter molecular mechanism increases the residence time of oxyanion’s hydration water and thus nitrate anion slows down the translational motion of neighbouring water. But it is also a “structure breaker” in that it accelerates the reorientation relaxation of hydration water. Such a result illustrates that differences do exist between the hydration of oxyanions and simple halide anions as a result of different molecular geometries. Furthermore, the rotation of the nitrate solute is coupled with the hydrogen bond rearrangement of its hydration water. The nitrate anion can either tilt along the axis perpendicularly to the plane or rotate in the plane. We find that the two reorientation relaxation routes of the hydration water lead to different relaxation dynamics in each of the two above movements of the nitrate solute. The current study suggests that molecular geometry could play an important role in solute hydration and dynamics

  15. The inhibition of methane hydrate formation by water alignment underneath surface adsorption of surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ngoc N.; Nguyen, Anh V.; Dang, Liem X.

    2017-06-01

    Sodium dodecyl sulfate (SDS) has been widely shown to strongly promote the formation of methane hydrate. Here we show that SDS displays an extraordinary inhibition effect on methane hydrate formation when the surfactant is used in sub-millimolar concentration (around 0.3 mM). We have also employed Sum Frequency Generation vibrational spectroscopy (SFG) and molecular dynamics simulation (MDS) to elucidate the molecular mechanism of this inhibition. The SFG and MDS results revealed a strong alignment of water molecules underneath surface adsorption of SDS in its sub-millimolar solution. Interestingly, both the alignment of water and the inhibition effect (in 0.3 mM SDS solution) went vanishing when an oppositely-charged surfactant (tetra-n-butylammonium bromide, TBAB) was suitably added to produce a mixed solution of 0.3 mM SDS and 3.6 mM TBAB. Combining structural and kinetic results, we pointed out that the alignment of water underneath surface adsorption of dodecyl sulfate (DS-) anions gave rise to the unexpected inhibition of methane hydration formation in sub-millimolar solution of SDS. The adoption of TBAB mitigated the SDS-induced electrostatic field at the solution’s surface and, therefore, weakened the alignment of interfacial water which, in turn, erased the inhibition effect. We discussed this finding using the concept of activation energy of the interfacial formation of gas hydrate. The main finding of this work is to reveal the interplay of interfacial water in governing gas hydrate formation which sheds light on a universal molecular-scale understanding of the influence of surfactants on gas hydrate formation. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.

  16. Selective and reactive hydration of nitriles to amides in water using silver nanoparticles stabilized by organic ligands

    International Nuclear Information System (INIS)

    Kawai, Koji; Kawakami, Hayato; Narushima, Takashi; Yonezawa, Tetsu

    2015-01-01

    Water-dispersible silver nanoparticles stabilized by silver–carbon covalent bonds were prepared. They exhibited high catalytic activities for the selective hydration of nitriles to amides in water. The activation of a nitrile group by the functional groups of the substrates and the hydrophobic layer on the nanoparticles influenced the catalyzed reaction were confirmed. Alkyl nitriles could also be selectively hydrated

  17. Molecular dynamics study of methane hydrate formation at a water/methane interface.

    Science.gov (United States)

    Zhang, Junfang; Hawtin, R W; Yang, Ye; Nakagava, Edson; Rivero, M; Choi, S K; Rodger, P M

    2008-08-28

    We present molecular dynamics simulation results of a liquid water/methane interface, with and without an oligomer of poly(methylaminoethylmethacrylate), PMAEMA. PMAEMA is an active component of a commercial low dosage hydrate inhibitor (LDHI). Simulations were performed in the constant NPT ensemble at temperatures of 220, 235, 240, 245, and 250 K and a pressure of 300 bar. The simulations show the onset of methane hydrate growth within 30 ns for temperatures below 245 K in the methane/water systems; at 240 K there is an induction period of ca. 20 ns, but at lower temperatures growth commences immediately. The simulations were analyzed to calculate hydrate content, the propensity for hydrogen bond formation, and how these were affected by both temperature and the presence of the LDHI. As expected, both the hydrogen bond number and hydrate content decreased with increasing temperature, though little difference was observed between the lowest two temperatures considered. In the presence of PMAEMA, the temperature below which sustained hydrate growth occurred was observed to decrease. Some of the implications for the role of PMAEMA in LDHIs are discussed.

  18. Types and characteristics of drinking water for hydration in the elderly.

    Science.gov (United States)

    Casado, Ángela; Ramos, Primitivo; Rodríguez, Jaime; Moreno, Norberto; Gil, Pedro

    2015-01-01

    The role of hydration in the maintenance of health is increasingly recognized. Hydration requirements vary for each person, depending on physical activity, environmental conditions, dietary patterns, alcohol intake, health problems, and age. Elderly individuals have higher risk of developing dehydration than adults. Diminution of liquid intake and increase in liquid losses are both involved in causing dehydration in the elderly. The water used for drinking is provided through regular public water supply and the official sanitary controls ensure their quality and hygiene, granting a range of variation for most of its physical and chemical characteristics, being sometimes these differences, though apparently small, responsible for some disorders in sensitive individuals. Hence, the advantages of using bottled water, either natural mineral water or spring water, are required by law to specify their composition, their major components, and other specific parameters. It is essential to take this into account to understand the diversity of indications and favorable effects on health that certain waters can offer.

  19. Molecular Dynamics Simulation of a Membrane/Water Interface : The Ordering of Water and Its Relation to the Hydration Force

    NARCIS (Netherlands)

    Marrink, Siewert-Jan; Berkowitz, Max; Berendsen, Herman J.C.

    1993-01-01

    In order to obtain a better understanding of the origin of the hydration force, three molecular dynamic simulations of phospholipid/water multilamellar systems were performed. The simulated systems only differed in the amount of interbilayer water, ranging from the minimum to the maximum amount of

  20. Transparent hydrogel with enhanced water retention capacity by introducing highly hydratable salt

    OpenAIRE

    Bai, Yuanyuan; Chen, Baohong; Xiang, Feng; Zhou, Jinxiong; Wang, Hong; Suo, Zhigang

    2014-01-01

    Polyacrylamide hydrogels containing salt as electrolyte have been used as highly stretchable transparent electrodes in flexible electronics, but those hydrogels are easy to dry out due to water evaporation. Targeted, we try to enhance water retention capacity of polyacrylamide hydrogel by introducing highly hydratable salts into the hydrogel. These hydrogels show enhanced water retention capacity in different level. Specially, polyacrylamide hydrogel containing high content of lithium chlorid...

  1. Prediction of hydroxyl concentrations in cement pore water using a numerical cement hydration model

    NARCIS (Netherlands)

    Eijk, van R.J.; Brouwers, H.J.H.

    2000-01-01

    In this paper, a 3D numerical cement hydration model is used for predicting alkali and hydroxyl concentrations in cement pore water. First, this numerical model is calibrated for Dutch cement employing both chemical shrinkage and calorimetric experiments. Secondly, the strength development of some

  2. Water distribution and related morphology in human stratum corneum at different hydration levels

    NARCIS (Netherlands)

    Bouwstra, J.A.; Graaff, de A.; Gooris, G.S.; Nijsse, J.; Wiechers, J.W.; Aelst, van A.C.

    2003-01-01

    This study focused on the water distribution in human stratum corneum and on the swelling of the corneocytes. For this purpose stratum corneum was hydrated to various levels and used either for Fourier transform infrared spectroscopy or for cryo-scanning electron microscopy. The images were analyzed

  3. 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.

  4. Comparison of skin hydration in combination and single use of common moisturizers (cream, toner, and spray water).

    Science.gov (United States)

    Yuanxi, Li; Wei, Hua; Lidan, Xiiong; Li, Li

    2016-01-01

    This study aims to assess the moisturization in combination or single use (including seven general applications) of three common moisturizers: cream, toner, and spray water. Groups were set as C: cream only; T: toner only; C+T, T+C: cream or toner applied successively within a few minutes; C-T, C-S: cream applied with repeated toner or spray water every 2 h; T-T: toner applied with repeated toner every 2 h; and N: untreated group. Outcomes were the change in skin hydration from baseline at 2, 4, 6, and 8 h after applications. All treated zones displayed a significantly higher degree of hydration compared with the untreated zone ( p skin (hydration value at baseline >35 a.u.), C-T led to greatest hydration change rate compared with others, followed by C+T, T+C, and C. Those three applications exhibited analogous hydration at each test point ( p > 0.05). The hydration rate of C-S differed slightly from T-T, followed by those four mentioned above, with T being the last. For dry skin (hydration value at baseline 0.05), the other results were identical. When cream and toner were applied successively, the application order has little effect on skin hydration. The application of cream only was an effective and brief way to achieve favorable moisturization especially for dry skin. As a complement, repeated application of toner rather than spray water is efficacious for skin hydration.

  5. Comparison of the rate constants for energy transfer in the light-harvesting protein, C-phycocyanin, calculated from Foerster`s theory and experimentally measured by time-resolved fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Debreczeny, Martin Paul [Univ. of California, Berkeley, CA (United States)

    1994-05-01

    We have measured and assigned rate constants for energy transfer between chromophores in the light-harvesting protein C-phycocyanin (PC), in the monomeric and trimeric aggregation states, isolated from Synechococcus sp. PCC 7002. In order to compare the measured rate constants with those predicted by Fdrster`s theory of inductive resonance in the weak coupling limit, we have experimentally resolved several properties of the three chromophore types ({beta}{sub 155} {alpha}{sub 84}, {beta}{sub 84}) found in PC monomers, including absorption and fluorescence spectra, extinction coefficients, fluorescence quantum yields, and fluorescence lifetimes. The cpcB/C155S mutant, whose PC is missing the {beta}{sub 155} chromophore, was, useful in effecting the resolution of the chromophore properties and in assigning the experimentally observed rate constants for energy transfer to specific pathways.

  6. Heat of hydration measurements on cemented radioactive wastes. Part 1: cement-water pastes

    International Nuclear Information System (INIS)

    Lee, D.J.

    1983-12-01

    This report describes the hydration of cement pastes in terms of chemical and kinetic models. A calorimetric technique was used to measure the heat of hydration to develop these models. The effects of temperature, water/cement ratio and cement replacements, ground granulated blast furnace slag (BFS) and pulverised fuel ash (PFA) on the hydration of ordinary Portland cement (OPC) is reported. The incorporation of BFS or PFA has a marked effect on the hydration reaction. The effect of temperature is also important but changing the water/cement ratio has little effect. Results from cement pastes containing only water and cement yield total heats of reaction of 400, 200 and 100 kJ/kg for OPC, BFS and PFA respectively. Using the results from the models which have been developed, the effect of major salts present in radioactive waste streams can be assessed. Values of the total heat of reaction, the time to complete 50 percent reaction, and the energy of activation, can be compared for different waste systems. (U.K.)

  7. Changes in Transepidermal Water Loss and Skin Hydration according to Expression of Aquaporin-3 in Psoriasis

    Science.gov (United States)

    Lee, Young; Je, Young-Jin; Lee, Sang-Sin; Li, Zheng Jun; Choi, Dae-Kyoung; Kwon, Yoo-Bin; Sohn, Kyung-Cheol; Im, Myung; Seo, Young Joon

    2012-01-01

    Background Aquaporins (AQPs) are a family of water transporting proteins present in many mammalian epithelial and endothelial cell types. Among the AQPs, AQP3 is known to be a water/glycerol transporter expressed in human skin. Objective The relationship between the expression level of AQP3 and transpidermal water loss (TEWL) in the lesional and peri-lesional skin of psoriasis-affected patients, and skin hydration in the lesional and peri-lesional skin of psoriasis patients, was investigated. Methods The expression of AQP3 in psoriasis-affected and healthy control skin was determined using immunohistochemical and immunofluroscence staining. TEWL and skin hydration were measured using a Tewameter® TM210 (Courage & Khazaka, Cologne, Germany) and a Corneometer® CM 820 (Courage & Khazaka), respectively. Results AQP3 was mainly expressed in the plasma membrane of stratum corneum and the stratum spinosum in normal epidermis. Unlike the normal epidermis, AQP3 showed decreased expression in the lesional and peri-lesional epidermis of psoriasis. TEWL was increased, and skin hydration was decreased, in the lesional and peri-lesional skin of psoriasis patients, compared with the healthy control sample. Conclusion Although various factors contribute to reduced skin hydration in the lesional and peri-lesional skin of psoriasis, AQP3 appears to be a key factor in the skin dehydration of psoriasis-affected skin. PMID:22577267

  8. A role for subducted super-hydrated kaolinite in Earth’s deep water cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Huijeong; Seoung, Donghoon; Lee, Yongjae; Liu, Zhenxian; Liermann, Hanns-Peter; Cynn, Hyunchae; Vogt, Thomas; Kao, Chi-Chang; Mao, Ho-Kwang

    2017-11-20

    Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slab (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H2O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.

  9. A role for subducted super-hydrated kaolinite in Earth's deep water cycle

    Science.gov (United States)

    Hwang, Huijeong; Seoung, Donghoon; Lee, Yongjae; Liu, Zhenxian; Liermann, Hanns-Peter; Cynn, Hyunchae; Vogt, Thomas; Kao, Chi-Chang; Mao, Ho-Kwang

    2017-12-01

    Water is the most abundant volatile component in the Earth. It continuously enters the mantle through subduction zones, where it reduces the melting temperature of rocks to generate magmas. The dehydration process in subduction zones, which determines whether water is released from the slab or transported into the deeper mantle, is an essential component of the deep water cycle. Here we use in situ and time-resolved high-pressure/high-temperature synchrotron X-ray diffraction and infrared spectra to characterize the structural and chemical changes of the clay mineral kaolinite. At conditions corresponding to a depth of about 75 km in a cold subducting slab (2.7 GPa and 200 °C), and in the presence of water, we observe the pressure-induced insertion of water into kaolinite. This super-hydrated phase has a unit cell volume that is about 31% larger, a density that is about 8.4% lower than the original kaolinite and, with 29 wt% H2O, the highest water content of any known aluminosilicate mineral in the Earth. As pressure and temperature approach 19 GPa and about 800 °C, we observe the sequential breakdown of super-hydrated kaolinite. The formation and subsequent breakdown of super-hydrated kaolinite in cold slabs subducted below 200 km leads to the release of water that may affect seismicity and help fuel arc volcanism at the surface.

  10. Transparent hydrogel with enhanced water retention capacity by introducing highly hydratable salt

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Yuanyuan; Xiang, Feng; Wang, Hong, E-mail: hwang@mail.xjtu.edu.cn, E-mail: suo@seas.harvard.edu [Electronic Materials Research Laboratory, School of Electronics and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Chen, Baohong; Zhou, Jinxiong [State Key Laboratory for Strength and Vibration of Mechanical Structures, International Center for Applied Mechanics and School of Aerospace, Xi' an Jiaotong University, Xi' an 710049 (China); Suo, Zhigang, E-mail: hwang@mail.xjtu.edu.cn, E-mail: suo@seas.harvard.edu [School of Engineering and Applied Sciences, Kavli Institute of Bionano Science and Technology, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2014-10-13

    Polyacrylamide hydrogels containing salt as electrolyte have been used as highly stretchable transparent electrodes in flexible electronics, but those hydrogels are easy to dry out due to water evaporation. Targeted, we try to enhance water retention capacity of polyacrylamide hydrogel by introducing highly hydratable salts into the hydrogel. These hydrogels show enhanced water retention capacity in different level. Specially, polyacrylamide hydrogel containing high content of lithium chloride can retain over 70% of its initial water even in environment with relative humidity of only 10% RH. The excellent water retention capacities of these hydrogels will make more applications of hydrogels become possible.

  11. Transparent hydrogel with enhanced water retention capacity by introducing highly hydratable salt

    International Nuclear Information System (INIS)

    Bai, Yuanyuan; Xiang, Feng; Wang, Hong; Chen, Baohong; Zhou, Jinxiong; Suo, Zhigang

    2014-01-01

    Polyacrylamide hydrogels containing salt as electrolyte have been used as highly stretchable transparent electrodes in flexible electronics, but those hydrogels are easy to dry out due to water evaporation. Targeted, we try to enhance water retention capacity of polyacrylamide hydrogel by introducing highly hydratable salts into the hydrogel. These hydrogels show enhanced water retention capacity in different level. Specially, polyacrylamide hydrogel containing high content of lithium chloride can retain over 70% of its initial water even in environment with relative humidity of only 10% RH. The excellent water retention capacities of these hydrogels will make more applications of hydrogels become possible.

  12. Studies on the fixation of tritiated water using the cement hydration, 2

    International Nuclear Information System (INIS)

    Nishimaki, Kenzo; Tsutsui, Tenson; Miake, Chiaki.

    1989-01-01

    In the previous paper, we have reported the results of basic experiments to fix tritiated water using the hydration of cement, and found that most tritiated water transfers to surrounding water, even if it is incorporated using the hydration of cement. In this report, we tried to apply a simple compartment model to the tritium transfer curves reported in the previous paper, which represent the phenomena that most water containing tritium is exchanging with a surrounding water, regardless of its forms, i.e., a crystalline water, free water and so on. We divided a solidified cement into three groupes with respect to the exchangeability of water, i.e., a compartment of fixed water, of compositions expect water, and of exchanging water. We developed a simple compartment model under the assumption that the water in the third compartment is exchangeable with the sorrounding water with a certain exchanging volume rate E, not altering by time. The transfer curves calculated with the model contains unknown parameter, E. By the method of least squares, varying the values of E, we could obtain most approximated transfer curves of tritium to those obtained by the previous experiments. In the result, we knew that the simple compartment model is applied to the tritium transfer curves reported in the previous paper. (author)

  13. Methane recovery from coal mine gas using hydrate formation in water-in-oil emulsions

    International Nuclear Information System (INIS)

    Zhong, Dong-Liang; Ding, Kun; Lu, Yi-Yu; Yan, Jin; Zhao, Wei-Long

    2016-01-01

    Highlights: • A water-in-oil emulsion was developed for CH_4 separation from coal mine methane gas. • Stable W/O emulsions were obtained with water cut in the range of (10–70%). • Gas hydrates nucleated faster with the reduction of water–oil volume ratio. • Gas uptake increased with the decrease of water–oil volume ratio. • CH_4 recovery was greatly enhanced by hydrate formation in W/O emulsions. - Abstract: In this work, a water-in-oil (W/O) emulsion was developed using liquid water, mineral oil, Sorbitan monooleate (Span 80), and cyclopentane. It was employed to enhance gas hydrate formation for CH_4 separation from a simulated coal mine methane (CMM) gas (30 mol% CH_4, 60 mol% N_2, and 10 mol% O_2). The stability test at atmospheric pressure and at a high pressure of 3.5 MPa showed that stable W/O emulsions were obtained when the water–oil volume ratio (WOR) was below 80%. The emulsified droplets size was measured with WOR ranging from 10% to 70%. Then kinetic experiments of CH_4 separation by hydrate formation in W/O emulsions were carried out at 273.6 K and (3.5–5.0) MPa in batch operation. The results indicated that water–oil volume ratio is a key factor that affects the kinetics of gas hydrate formation from the CMM gas mixture. Hydrate nucleation was observed to occur faster while WOR was decreased, and gas uptake increased significantly with the decrease of WOR. CH_4 concentration in the recovered gas mixture was increased to 52 mol% as compared to 30 mol% in the original gas mixture through one-stage hydrate formation in the W/O emulsions. It was found that the experimental conditions of 273.6 K, 3.5 MPa and WOR = 30% were favorable for CH_4 recovery from the CMM gas. The CH_4 recovery obtained under these conditions was 43%. It was higher than those obtained at WOR = 10% and 70%, and was greatly increased as compared with those obtained in the same reactor with the presence of TBAB (26%) and CP (33%).

  14. Differential scanning calorimetric study of the binding between native DNA and its primary water of hydration.

    Science.gov (United States)

    Marlowe, R. L.; Lukan, A. M.; Lee, S. A.; Anthony, L.; Rupprecht, A.

    1996-03-01

    Differential scanning calorimetry was used to measure the binding strength between calf-thymus DNA and its primary water of hydration. The specific heat of wet-spun films was found to have a broad endothermic transition near 80 ^oC and a sharp exothermic transition near 250 ^oC. The broad transition is believed to be mainly due to the breaking of the bonds of the strongly bound water of hydration. This transition was found to be reversible, as expected. Kissinger analysis indicates that the activation barrier for breaking the bonds of these water molecules is about 0.6 eV. The sharp transition appeared to be an indication of a thermal decomposition of the DNA. Samples taken above this transition lost mass, showed evidence of having melted, and had turned black in color. This transition is irreversible.

  15. The dynamics of water in hydrated white bread investigated using quasielastic neutron scattering

    International Nuclear Information System (INIS)

    Sjoestroem, J; Kargl, F; Fernandez-Alonso, F; Swenson, J

    2007-01-01

    The dynamics of water in fresh and in rehydrated white bread is studied using quasielastic neutron scattering (QENS). A diffusion constant for water in fresh bread, without temperature gradients and with the use of a non-destructive technique, is presented here for the first time. The self-diffusion constant for fresh bread is estimated to be D s = 3.8 x 10 -10 m 2 s -1 and the result agrees well with previous findings for similar systems. It is also suggested that water exhibits a faster dynamics than previously reported in the literature using equilibration of a hydration-level gradient monitored by vibrational spectroscopy. The temperature dependence of the dynamics of low hydration bread is also investigated for T = 280-350 K. The average relaxation time at constant momentum transfer (Q) shows an Arrhenius behavior in the temperature range investigated

  16. Hydrazine - hydrate water regime and operation of fuel elements

    International Nuclear Information System (INIS)

    Pashevitch, V.I.; Pashevitch, D.V.; Bogancs, J.; Tilky, P.

    1997-01-01

    Water chemistries currently used in WWER reactors are potassium based water chemistry (KOH) to adjust the pH with ammonia or hydrazine as oxygen scavenger. Based on the measurements of Zr 95 which is a corrosion product of the zirconium cladding, it is shown in this paper that the amount of corrosion products accompanying the reactor shutdown is smaller when hydrazine is used. This is particularly obvious on PAKS 1 and 2 when Zr 95 measurements are performed before and after switching the water chemistry from ammonia to hydrazine. It is concluded that the main advantage of using the hydrazine water chemistry is to decrease the thickness of the corrosion product layer formed on the fuel cladding, therefore the fuel temperature can be kept low. It is estimated that the fuel temperature increase due to the layer of corrosion products is 120 deg. C for KOLA 3 which is operated with ammonia water chemistry. (author). 5 figs

  17. Hydrazine - hydrate water regime and operation of fuel elements

    Energy Technology Data Exchange (ETDEWEB)

    Pashevitch, V I; Pashevitch, D V [Pand Co. (Russian Federation); Bogancs, J; Tilky, P [Paks NPP (Hungary)

    1997-02-01

    Water chemistries currently used in WWER reactors are potassium based water chemistry (KOH) to adjust the pH with ammonia or hydrazine as oxygen scavenger. Based on the measurements of Zr 95 which is a corrosion product of the zirconium cladding, it is shown in this paper that the amount of corrosion products accompanying the reactor shutdown is smaller when hydrazine is used. This is particularly obvious on PAKS 1 and 2 when Zr 95 measurements are performed before and after switching the water chemistry from ammonia to hydrazine. It is concluded that the main advantage of using the hydrazine water chemistry is to decrease the thickness of the corrosion product layer formed on the fuel cladding, therefore the fuel temperature can be kept low. It is estimated that the fuel temperature increase due to the layer of corrosion products is 120 deg. C for KOLA 3 which is operated with ammonia water chemistry. (author). 5 figs.

  18. Dynamic lifetimes of cagelike water clusters immersed in liquid water and their implications for hydrate nucleation studies

    Energy Technology Data Exchange (ETDEWEB)

    Guo, G.J.; Zhang, Y.G.; Li, M.; Wu, C.H. [Chinese Academy of Sciences, Inst. of Geology and Geophysics, Beijing (China). Key Laboratory of the Study of Earth' s Deep Interior

    2008-07-01

    In hydrate research fields, the hydrate nucleation mechanism still remains as an unsolved question. The static lifetimes of cagelike water clusters (CLWC) immersed in bulk liquid water have recently been measured by performing molecular dynamics simulations in the methane-water system, during which the member-water molecules of CLWCs are not allowed to exchange with their surrounding water molecules. This paper presented a study that measured the dynamic lifetimes of CLWCs permitting such water exchanges. The study involved re-analysis of previous simulation data that were used to study the effect of methane adsorption on the static lifetimes of a dodecahedral water cluster (DWC). The dynamic lifetimes of the DWC were calculated. The results of lifetime measurements of DWC in different systems were provided. The implications of this study for hydrate nucleation were also discussed. It was found that the dynamic lifetimes of CLWCs were not less than the static lifetimes previously obtained, and their ratio increased with the lifetime values. The results strengthened that CLWCs are metastable structures in liquid water and the occurrence probability of long-lived CLWCs will increase if one uses the dynamic lifetimes instead of the static lifetimes. 13 refs., 1 tab., 3 figs.

  19. Skin hydration: interplay between molecular dynamics, structure and water uptake in the stratum corneum.

    Science.gov (United States)

    Mojumdar, Enamul Haque; Pham, Quoc Dat; Topgaard, Daniel; Sparr, Emma

    2017-11-16

    Hydration is a key aspect of the skin that influences its physical and mechanical properties. Here, we investigate the interplay between molecular and macroscopic properties of the outer skin layer - the stratum corneum (SC) and how this varies with hydration. It is shown that hydration leads to changes in the molecular arrangement of the peptides in the keratin filaments as well as dynamics of C-H bond reorientation of amino acids in the protruding terminals of keratin protein within the SC. The changes in molecular structure and dynamics occur at a threshold hydration corresponding to ca. 85% relative humidity (RH). The abrupt changes in SC molecular properties coincide with changes in SC macroscopic swelling properties as well as mechanical properties in the SC. The flexible terminals at the solid keratin filaments can be compared to flexible polymer brushes in colloidal systems, creating long-range repulsion and extensive swelling in water. We further show that the addition of urea to the SC at reduced RH leads to similar molecular and macroscopic responses as the increase in RH for SC without urea. The findings provide new molecular insights to deepen the understanding of how intermediate filament organization responds to changes in the surrounding environment.

  20. 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.

  1. STUDY ON THE FACTORS INFLUENCING HYDRATION AND WATER RETENTION CAPACITY OF MEAT

    OpenAIRE

    DANIELA IANIłCHI; CARMEN NICOLAE; CRISTIANA DIACONESCU; GABRIELA MALOS; I. G. MALOS

    2008-01-01

    Top-quality food produce and high profitability in processing requires high quality in raw materials. Therefore, to achieve these objectives, it is imperative to know the properties of the war materials, and the factors that influence these properties.The properties of the meat directly involved in increasing economic efficiency and final produce quality are the so-called technological properties: hydration capacity and water retention capacity of meat. These properties are determined by some...

  2. Analysis of the hydration water around bovine serum albumin using terahertz coherent synchrotron radiation.

    Science.gov (United States)

    Bye, Jordan W; Meliga, Stefano; Ferachou, Denis; Cinque, Gianfelice; Zeitler, J Axel; Falconer, Robert J

    2014-01-09

    Terahertz spectroscopy was used to study the absorption of bovine serum albumin (BSA) in water. The Diamond Light Source operating in a low alpha mode generated coherent synchrotron radiation that covered a useable spectral bandwidth of 0.3-3.3 THz (10-110 cm(-1)). As the BSA concentration was raised, there was a nonlinear change in absorption inconsistent with Beer's law. At low BSA concentrations (0-1 mM), the absorption remained constant or rose slightly. Above a concentration of 1 mM BSA, a steady decrease in absorption was observed, which was followed by a plateau that started at 2.5 mM. Using a overlapping hydration layer model, the hydration layer was estimated to extend 15 Å from the protein. Calculation of the corrected absorption coefficient (αcorr) for the water around BSA by subtracting the excluded volume of the protein provides an alternative approach to studying the hydration layer that provides evidence for complexity in the population of water around BSA.

  3. Coordination variation of hydrated Cu2+/Br1− ions traversing the interfacial water in mesopores

    Directory of Open Access Journals (Sweden)

    Q. Wang

    2012-06-01

    Full Text Available Resolution of the atomistic and electronic details about the coordination structure variation of hydrated ions in the interfacial water is still a tough challenge, which is, however, essentially important for the understanding of ion adsorption, permeation and other similar processes in aqueous solutions. Here we report the tracing of coordination structure variation for hydrated Cu2+/Br1- ions traversing the interfacial water in Vycor mesopores (ϕ = 7.6 nm by employing both X-ray absorption near edge structure and extended X-ray absorption fine structure spectroscopies. By controlled desorption/adsorption of water, the filling fraction of the mesopores, thus the water layer thickness, can be adjusted, which in turn effects the variation of coordination structure of the ions therein. It is found that both Cu2+ and Br1- ions prefer staying exclusively in the core water, and in this circumstance no ion pairs have been detected in the solution of concentrations up to 1.0 M. Following capillary decondensation occurring at a filling fraction of ∼35% which corresponds to a water layer of about three monolayers, Br1- ions begin immediately to reconstruct their first coordination shell, characterized by ionic dehydration, shrinkage of ion-water bond length, and formation of ion pairs. In contrast, Cu2+ ions can retain a bulk-like coordination structure till being driven to bond directly to the pore surface when the filling fraction is below 20%. At the final stage of dehydration via thermal vacuum treatment at 110°C, Cu2+ ions can be completely reduced to the Cu1+ state, and recover at room temperature only when the filling fraction is above 14%. These results may be inspirable for the investigation of similar problems concerning hydrated ions in water solution under different confining conditions.

  4. 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.

  5. Hydration of a Large Anionic Charge Distribution - Naphthalene-Water Cluster Anions

    Science.gov (United States)

    Weber, J. Mathias; Adams, Christopher L.

    2010-06-01

    We report the infrared spectra of anionic clusters of naphthalene with up to three water molecules. Comparison of the experimental infrared spectra with theoretically predicted spectra from quantum chemistry calculations allow conclusions regarding the structures of the clusters under study. The first water molecule forms two hydrogen bonds with the π electron system of the naphthalene moiety. Subsequent water ligands interact with both the naphthalene and the other water ligands to form hydrogen bonded networks, similar to other hydrated anion clusters. Naphthalene-water anion clusters illustrate how water interacts with negative charge delocalized over a large π electron system. The clusters are interesting model systems that are discussed in the context of wetting of graphene surfaces and polyaromatic hydrocarbons.

  6. The impact of kosmotropes and chaotropes on bulk and hydration shell water dynamics in a model peptide solution

    International Nuclear Information System (INIS)

    Russo, Daniela

    2008-01-01

    Kosmotropic (order-making) and chaotropic (order-breaking) co-solvents influence stability and biochemical equilibrium in aqueous solutions of proteins, acting indirectly through the structure and dynamics of the hydration water that surrounds the protein molecules. We have investigated the influence of kosmotropic and chaotropic co-solvents on the hydrogen bonding network dynamics of both bulk water and hydration water. To this end the evolution of bulk water and hydration water dynamics of a prototypical hydrophobic amino acid with polar backbone, N-acetyl-leucine-methylamide (NALMA), has been studied by quasielastic neutron scattering as a function of solvent composition. The results show that bulk water and hydration water dynamics, apart from a dynamical suppression that depends on the NALMA solute, exhibit the same dependence on addition of co-solvent for all of the co-solvents studied (urea, glycerol, MgSO 4 , and dimethyl sulfoxide). The hydrophobic solute and the high concentration water-structuring additive have the same effect on the water hydrogen bonding network. Water remains the preferential hydration of the hydrophobic side chain and backbone. We also find that the reorganization of the bulk water hydrogen bond network, upon addition of kosmotrope and chaotrope additives, is not dynamically perturbed, and that the hydrogen bond lifetime is maintained at 1 ps as in pure bulk water. On the other hand the addition of NALMA to the water/co-solvent binary system causes reorganization of the hydrogen bonds, resulting in an increased hydrogen bond lifetime. Furthermore, the solute's side chain dynamics is not affected by high concentrations of co-solvent. We shall discuss the hydration dynamics results in the context of protein folding and protein-solvent interactions

  7. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    Energy Technology Data Exchange (ETDEWEB)

    Varanasi, S. R., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de; John, A. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Guskova, O. A., E-mail: s.raovaranasi@uq.edu.au, E-mail: guskova@ipfdd.de [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Sommer, J.-U. [Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden D-01069 (Germany); Dresden Center for Computational Materials Science (DCMS), Technische Universität Dresden, Dresden D-01069 (Germany); Institut für Theoretische Physik, Technische Universität Dresden, Zellescher Weg 17, Dresden D-01069 (Germany)

    2015-06-14

    Fullerene C{sub 60} sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C{sub 60} fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C{sub 60} are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique.

  8. Prediction of Water Binding to Protein Hydration Sites with a Discrete, Semiexplicit Solvent Model.

    Science.gov (United States)

    Setny, Piotr

    2015-12-08

    Buried water molecules are ubiquitous in protein structures and are found at the interface of most protein-ligand complexes. Determining their distribution and thermodynamic effect is a challenging yet important task, of great of practical value for the modeling of biomolecular structures and their interactions. In this study, we present a novel method aimed at the prediction of buried water molecules in protein structures and estimation of their binding free energies. It is based on a semiexplicit, discrete solvation model, which we previously introduced in the context of small molecule hydration. The method is applicable to all macromolecular structures described by a standard all-atom force field, and predicts complete solvent distribution within a single run with modest computational cost. We demonstrate that it indicates positions of buried hydration sites, including those filled by more than one water molecule, and accurately differentiates them from sterically accessible to water but void regions. The obtained estimates of water binding free energies are in fair agreement with reference results determined with the double decoupling method.

  9. The Structure and Transport of Water and Hydrated Ions Within Hydrophobic, Nanoscale Channels

    International Nuclear Information System (INIS)

    Holt, J.K.; Herberg, J.L.; Wu, Y.; Schwegler, E.; Mehta, A.

    2009-01-01

    The purpose of this project includes an experimental and modeling investigation into water and hydrated ion structure and transport at nanomaterials interfaces. This is a topic relevant to understanding the function of many biological systems such as aquaporins that efficiently shuttle water and ion channels that permit selective transport of specific ions across cell membranes. Carbon nanotubes (CNT) are model nanoscale, hydrophobic channels that can be functionalized, making them artificial analogs for these biological channels. This project investigates the microscopic properties of water such as water density distributions and dynamics within CNTs using Nuclear Magnetic Resonance (NMR) and the structure of hydrated ions at CNT interfaces via X-ray Absorption Spectroscopy (XAS). Another component of this work is molecular simulation, which can predict experimental measurables such as the proton relaxation times, chemical shifts, and can compute the electronic structure of CNTs. Some of the fundamental questions this work is addressing are: (1) what is the length scale below which nanoscale effects such as molecular ordering become important, (2) is there a relationship between molecular ordering and transport?, and (3) how do ions interact with CNT interfaces? These are questions of interest to the scientific community, but they also impact the future generation of sensors, filters, and other devices that operate on the nanometer length scale. To enable some of the proposed applications of CNTs as ion filtration media and electrolytic supercapacitors, a detailed knowledge of water and ion structure at CNT interfaces is critical.

  10. Water around fullerene shape amphiphiles: A molecular dynamics simulation study of hydrophobic hydration

    International Nuclear Information System (INIS)

    Varanasi, S. R.; John, A.; Guskova, O. A.; Sommer, J.-U.

    2015-01-01

    Fullerene C 60 sub-colloidal particle with diameter ∼1 nm represents a boundary case between small and large hydrophobic solutes on the length scale of hydrophobic hydration. In the present paper, a molecular dynamics simulation is performed to investigate this complex phenomenon for bare C 60 fullerene and its amphiphilic/charged derivatives, so called shape amphiphiles. Since most of the unique properties of water originate from the pattern of hydrogen bond network and its dynamics, spatial, and orientational aspects of water in solvation shells around the solute surface having hydrophilic and hydrophobic regions are analyzed. Dynamical properties such as translational-rotational mobility, reorientational correlation and occupation time correlation functions of water molecules, and diffusion coefficients are also calculated. Slower dynamics of solvent molecules—water retardation—in the vicinity of the solutes is observed. Both the topological properties of hydrogen bond pattern and the “dangling” –OH groups that represent surface defects in water network are monitored. The fraction of such defect structures is increased near the hydrophobic cap of fullerenes. Some “dry” regions of C 60 are observed which can be considered as signatures of surface dewetting. In an effort to provide molecular level insight into the thermodynamics of hydration, the free energy of solvation is determined for a family of fullerene particles using thermodynamic integration technique

  11. Phase equilibrium condition measurements in nitrogen and air clathrate hydrate forming systems at temperatures below freezing point of water

    International Nuclear Information System (INIS)

    Yasuda, Keita; Oto, Yuya; Shen, Renkai; Uchida, Tsutomu; Ohmura, Ryo

    2013-01-01

    Highlights: • Phase equilibrium conditions in the nitrogen and modelled air hydrate forming systems are measured. • Measurements are conducted at temperatures below the freezing point of water. • Results have relevance to the air hydrate formation in the ice sheets. • Measured data are quantitatively compared with the previously reported values. • Range of the equilibrium measurements was from (242 to 268) K. -- Abstract: Contained in this paper are the three phase equilibrium conditions of the (ice + clathrate hydrate + guest-rich) vapour in the (nitrogen + water) and the modelled (air + water) systems at temperatures below the freezing point of water. The precise determination of the equilibrium conditions in those systems are of importance for the analysis of the past climate change using the cored samples from the ice sheets at Antarctica and Greenland because the air hydrates keep the ancient climate signals. The mole ratio of the modelled air composed of nitrogen and oxygen is 0.790:0.210. The equilibrium conditions were measured by the batch, isochoric procedure. The temperature range of the measurements in the nitrogen hydrate forming system is (244.05 < T < 266.55) K and the corresponding equilibrium pressure range is (7.151 < p < 12.613) MPa. The temperature range of the measurements in the modelled air hydrate forming system is (242.55 < T < 267.85) K, and the corresponding equilibrium pressure range is (6.294 < p < 12.144) MPa. The data obtained quantitatively compared with the previously reported data

  12. Confined Water in Layered Silicates: The Origin of Anomalous Thermal Expansion Behavior in Calcium-Silicate-Hydrates

    International Nuclear Information System (INIS)

    Krishnan, N. M. Anoop; Wang, Bu; Falzone, Gabriel; Le Pape, Yann; Neithalath, Narayanan

    2016-01-01

    Water, under conditions of nanoscale confinement, exhibits anomalous dynamics, and enhanced thermal deformations, which may be further enhanced when such water is in contact with hydrophilic surfaces. Such heightened thermal deformations of water could control the volume stability of hydrated materials containing nanoconfined structural water. Understanding and predicting the thermal deformation coefficient (TDC, often referred to as the CTE, coefficient of thermal expansion), which represents volume changes induced in materials under conditions of changing temperature, is of critical importance for hydrated solids including: hydrogels, biological tissues, and calcium silicate hydrates, as changes in their volume can result in stress development, and cracking. By pioneering atomistic simulations, we examine the physical origin of thermal expansion in calcium-silicate-hydrates (C–S–H), the binding agent in concrete that is formed by the reaction of cement with water. We report that the TDC of C–S–H shows a sudden increase when the CaO/SiO_2 (molar ratio; abbreviated as Ca/Si) exceeds 1.5. This anomalous behavior arises from a notable increase in the confinement of water contained in the C–S–H’s nanostructure. We identify that confinement is dictated by the topology of the C–S–H’s atomic network. Altogether, the results suggest that thermal deformations of hydrated silicates can be altered by inducing compositional changes, which in turn alter the atomic topology and the resultant volume stability of the solids.

  13. Confined Water in Layered Silicates: The Origin of Anomalous Thermal Expansion Behavior in Calcium-Silicate-Hydrates.

    Science.gov (United States)

    Krishnan, N M Anoop; Wang, Bu; Falzone, Gabriel; Le Pape, Yann; Neithalath, Narayanan; Pilon, Laurent; Bauchy, Mathieu; Sant, Gaurav

    2016-12-28

    Water, under conditions of nanoscale confinement, exhibits anomalous dynamics, and enhanced thermal deformations, which may be further enhanced when such water is in contact with hydrophilic surfaces. Such heightened thermal deformations of water could control the volume stability of hydrated materials containing nanoconfined structural water. Understanding and predicting the thermal deformation coefficient (TDC, often referred to as the CTE, coefficient of thermal expansion), which represents volume changes induced in materials under conditions of changing temperature, is of critical importance for hydrated solids including: hydrogels, biological tissues, and calcium silicate hydrates, as changes in their volume can result in stress development, and cracking. By pioneering atomistic simulations, we examine the physical origin of thermal expansion in calcium-silicate-hydrates (C-S-H), the binding agent in concrete that is formed by the reaction of cement with water. We report that the TDC of C-S-H shows a sudden increase when the CaO/SiO 2 (molar ratio; abbreviated as Ca/Si) exceeds 1.5. This anomalous behavior arises from a notable increase in the confinement of water contained in the C-S-H's nanostructure. We identify that confinement is dictated by the topology of the C-S-H's atomic network. Taken together, the results suggest that thermal deformations of hydrated silicates can be altered by inducing compositional changes, which in turn alter the atomic topology and the resultant volume stability of the solids.

  14. 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.

  15. Acid-base balance and hydration status following consumption of mineral-based alkaline bottled water

    Directory of Open Access Journals (Sweden)

    Heil Daniel P

    2010-09-01

    Full Text Available Abstract Background The present study sought to determine whether the consumption of a mineral-rich alkalizing (AK bottled water could improve both acid-base balance and hydration status in young healthy adults under free-living conditions. The AK water contains a naturally high mineral content along with Alka-PlexLiquid™, a dissolved supplement that increases the mineral content and gives the water an alkalizing pH of 10.0. Methods Thirty-eight subjects were matched by gender and self-reported physical activity (SRPA, hrs/week and then split into Control (12 women, 7 men; Mean +/- SD: 23 +/- 2 yrs; 7.2 +/- 3.6 hrs/week SRPA and Experimental (13 women, 6 men; 22 +/- 2 yrs; 6.4 +/- 4.0 hrs/week SRPA groups. The Control group consumed non-mineralized placebo bottled water over a 4-week period while the Experimental group consumed the placebo water during the 1st and 4th weeks and the AK water during the middle 2-week treatment period. Fingertip blood and 24-hour urine samples were collected three times each week for subsequent measures of blood and urine osmolality and pH, as well as total urine volume. Dependent variables were analyzed using multivariate repeated measures ANOVA with post-hoc focused on evaluating changes over time within Control and Experimental groups (alpha = 0.05. Results There were no significant changes in any of the dependent variables for the Control group. The Experimental group, however, showed significant increases in both the blood and urine pH (6.23 to 7.07 and 7.52 to 7.69, respectively, a decreased blood and increased urine osmolality, and a decreased urine output (2.51 to 2.05 L/day, all during the second week of the treatment period (P Conclusions Consumption of AK water was associated with improved acid-base balance (i.e., an alkalization of the blood and urine and hydration status when consumed under free-living conditions. In contrast, subjects who consumed the placebo bottled water showed no changes over the

  16. STUDY ON THE FACTORS INFLUENCING HYDRATION AND WATER RETENTION CAPACITY OF MEAT

    Directory of Open Access Journals (Sweden)

    DANIELA IANIłCHI

    2008-10-01

    Full Text Available Top-quality food produce and high profitability in processing requires high quality in raw materials. Therefore, to achieve these objectives, it is imperative to know the properties of the war materials, and the factors that influence these properties.The properties of the meat directly involved in increasing economic efficiency and final produce quality are the so-called technological properties: hydration capacity and water retention capacity of meat. These properties are determined by some factors belonging to the intrinsic quality of meat, animal slaughter methods, technological operations applied to the meat, and the auxiliary materials used.

  17. Heterogeneous Nucleation of Methane Hydrate in a Water-Decane-Methane Emulsion

    Science.gov (United States)

    Shestakov, V. A.; Kosyakov, V. I.; Manakov, A. Yu.; Stoporev, A. S.; Grachev, E. V.

    2018-07-01

    Heterogeneous nucleation in disperse systems with metastable disperse phases plays an important role in the mechanisms of environmental and technological processes. The effect the concentration and activity of particles that initiate the formation of a new phase have on nucleation processes in such systems is considered. An approach is proposed that allows construction of a spectrum of particle activity characterizing the features of nucleation in a sample, based on the fraction of crystallized droplets depending on the level of supercooling and the use of Weibull's distribution. The proposed method is used to describe experimental data on the heterogeneous nucleation of methane hydrate in an emulsion in a water-decane-methane system.

  18. Hydration level is an internal variable for computing motivation to obtain water rewards in monkeys.

    Science.gov (United States)

    Minamimoto, Takafumi; Yamada, Hiroshi; Hori, Yukiko; Suhara, Tetsuya

    2012-05-01

    In the process of motivation to engage in a behavior, valuation of the expected outcome is comprised of not only external variables (i.e., incentives) but also internal variables (i.e., drive). However, the exact neural mechanism that integrates these variables for the computation of motivational value remains unclear. Besides, the signal of physiological needs, which serves as the primary internal variable for this computation, remains to be identified. Concerning fluid rewards, the osmolality level, one of the physiological indices for the level of thirst, may be an internal variable for valuation, since an increase in the osmolality level induces drinking behavior. Here, to examine the relationship between osmolality and the motivational value of a water reward, we repeatedly measured the blood osmolality level, while 2 monkeys continuously performed an instrumental task until they spontaneously stopped. We found that, as the total amount of water earned increased, the osmolality level progressively decreased (i.e., the hydration level increased) in an individual-dependent manner. There was a significant negative correlation between the error rate of the task (the proportion of trials with low motivation) and the osmolality level. We also found that the increase in the error rate with reward accumulation can be well explained by a formula describing the changes in the osmolality level. These results provide a biologically supported computational formula for the motivational value of a water reward that depends on the hydration level, enabling us to identify the neural mechanism that integrates internal and external variables.

  19. Active-Site Hydration and Water Diffusion in Cytochrome P450cam: A Highly Dynamic Process

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinglong [ORNL; Baudry, Jerome Y [ORNL

    2011-01-01

    Long-timescale molecular dynamics simulations (300 ns) are performed on both the apo- (i.e., camphor-free) and camphor-bound cytochrome P450cam (CYP101). Water diffusion into and out of the protein active site is observed without biased sampling methods. During the course of the molecular dynamics simulation, an average of 6.4 water molecules is observed in the camphor-binding site of the apo form, compared to zero water molecules in the binding site of the substrate-bound form, in agreement with the number of water molecules observed in crystal structures of the same species. However, as many as 12 water molecules can be present at a given time in the camphor-binding region of the active site in the case of apo-P450cam, revealing a highly dynamic process for hydration of the protein active site, with water molecules exchanging rapidly with the bulk solvent. Water molecules are also found to exchange locations frequently inside the active site, preferentially clustering in regions surrounding the water molecules observed in the crystal structure. Potential-of-mean-force calculations identify thermodynamically favored trans-protein pathways for the diffusion of water molecules between the protein active site and the bulk solvent. Binding of camphor in the active site modifies the free-energy landscape of P450cam channels toward favoring the diffusion of water molecules out of the protein active site.

  20. Effects of Water Provision and Hydration on Cognitive Function among Primary-School Pupils in Zambia: A Randomized Trial.

    Directory of Open Access Journals (Sweden)

    Victoria Trinies

    Full Text Available There is a well-established link between hydration and improved cognitive performance among adults, with evidence of similar findings among children. No trials have investigated the impact of water provision on cognitive performance among schoolchildren in hot and arid low-resource settings. We conducted a randomized-controlled trial in five schools with limited water access in Chipata district in Eastern province, Zambia, to assess the efficacy of water provision on cognition. Pupils in grades 3-6 were randomly assigned to either receive a bottle of drinking water that they could refill throughout the day (water group, n = 149 or only have access to drinking water that was normally available at the school (control group, n = 143. Hydration was assessed in the morning before provision of water and in the afternoon through urine specific gravity (Usg measured with a portable refractometer. In the afternoon we administered six cognitive tests to assess short-term memory, concentration, visual attention, and visual motor skills. Morning prevalence of dehydration, defined as Usg≥1.020, was 42%. Afternoon dehydration increased to 67% among the control arm and dropped to 10% among the intervention arm. We did not find that provision of water or hydration impacted cognitive test scores, although there were suggestive relationships between both water provision and hydration and increased scores on tests measuring visual attention. We identified key improvements to the study design that are warranted to further investigate this relationship.ClinicalTrials.gov NCT01924546.

  1. Structural Interpretation of the Large Slowdown of Water Dynamics at Stacked Phospholipid Membranes for Decreasing Hydration Level: All-Atom Molecular Dynamics

    Directory of Open Access Journals (Sweden)

    Carles Calero

    2016-04-01

    Full Text Available Hydration water determines the stability and function of phospholipid membranes as well as the interaction of membranes with other molecules. Experiments and simulations have shown that water dynamics slows down dramatically as the hydration decreases, suggesting that the interfacial water that dominates the average dynamics at low hydration is slower than water away from the membrane. Here, based on all-atom molecular dynamics simulations, we provide an interpretation of the slowdown of interfacial water in terms of the structure and dynamics of water–water and water–lipid hydrogen bonds (HBs. We calculate the rotational and translational slowdown of the dynamics of water confined in stacked phospholipid membranes at different levels of hydration, from completely hydrated to poorly hydrated membranes. For all hydrations, we analyze the distribution of HBs and find that water–lipids HBs last longer than water–water HBs and that at low hydration most of the water is in the interior of the membrane. We also show that water–water HBs become more persistent as the hydration is lowered. We attribute this effect (i to HBs between water molecules that form, in turn, persistent HBs with lipids; (ii to the hindering of the H-bonding switching between water molecules due to the lower water density at the interface; and (iii to the higher probability of water–lipid HBs as the hydration decreases. Our interpretation of the large dynamic slowdown in water under dehydration is potentially relevant in understanding membrane biophysics at different hydration levels.

  2. The phase equilibria of multicomponent gas hydrate in methanol/ethylene glycol solution based formation water

    International Nuclear Information System (INIS)

    Xu, Shurui; Fan, Shuanshi; Yao, Haiyuan; Wang, Yanhong; Lang, Xuemei; Lv, Pingping; Fang, Songtian

    2017-01-01

    Highlights: • The equilibrium data in THI solution based formation water is first investigated. • The 0.55 mass fraction concentration of EG 0.55 mass fraction fills the vacancy of this area. • The testing pressure range from 4.22 MPa to 34.72 MPa was rare in published data. - Abstract: In this paper, the three-phase coexistence points are generated for multicomponent gas hydrate in methanol (MeOH) solution for (0.05, 0.10, 0.15, and 0.35) mass fraction and ethylene glycol (EG) solution for (0.05, 0.10, 0.15, 0.35, 0.40 and 0.55) mass fraction. The phase equilibrium curves of different system were obtained by an isochoric pressure-search method on high pressure apparatus. The phase equilibrium regions of multicomponent gas hydrate were measured using the same composition of natural gas distributed in the South China Sea. And the different concentration solutions were prepared based formation water. The experimental data were measured in a wide range temperature from 267.74 to 298.53 K and a wide range pressure from 4.22 MPa to 34.72 MPa. The results showed that the hydrate phase equilibrium curves shifted to the inhibition region in accordance with the increased inhibitor concentration. In addition, the equilibrium temperature would decrease about 2.7 K when the concentration of MeOH increased 0.05 mass fraction. Besides, the suppression temperature was 1.25 K with the 0.05 mass fraction increase of EG concentration in the range of 0.05 mass fraction to 0.15 mass fraction. While in high EG concentration region, the suppression temperature was 3.3 K with the same increase of EG concentration (0.05 mass fraction).

  3. Solvation numbers and hydration constant for thorium(IV) in ethanol-water medium

    International Nuclear Information System (INIS)

    Sedaira, H.; Idriss, K.A.; Hashem, E.Y.

    1996-01-01

    The solvation number and hydration constant of Th 4+ in ethanol-water medium were determined at 25 degrees C using UV-spectral and electrochemical measurements. A solvate formation equilibrium is demonstrated and characterized. Three molecules of ethanol (S) can bond to the metal cation with strengths comparable to that for H 2 O to form ThS 3 (H 2 O) 3 4+ . Formation of thorium monochelate with lawsone (2-hydroxy-1.4-naphthoquinone) eliminates bonding with alcohol molecules. The dissociation constant of the chelating agent s K a and the formation contant of the monochelated metal ion s K f * that are essentially independent of the solution composition are evaluated. Hydration titrations involving thorium-lawsone monochlate are performed and the data obtained from the changes of pH with solvent composition are analyzed. The solution independent constant, s K f * for thorium-lawsone complex formation in mixed aqueous ethanol is given by log x K f * =vpK a + log s K h - log [LH] - vpH + 3 log v where vpK a is the dissociation constant of the chelating agent LH in the solvent system of v volume fraction of water and s K h is the solution-independent hydration constant of thorium (IV) in the solvent system. Log-values for the constants s K h , s K f * and s K z * are found to be 7.8 ±0.02, 11.38±0.04 and -0.753, respectively

  4. Diffusion and spectroscopy of water and lipids in fully hydrated dimyristoylphosphatidylcholine bilayer membranes

    International Nuclear Information System (INIS)

    Yang, J.; Martí, J.; Calero, C.

    2014-01-01

    Microscopic structure and dynamics of water and lipids in a fully hydrated dimyristoylphosphatidylcholine phospholipid lipid bilayer membrane in the liquid-crystalline phase have been analyzed with all-atom molecular dynamics simulations based on the recently parameterized CHARMM36 force field. The diffusive dynamics of the membrane lipids and of its hydration water, their reorientational motions as well as their corresponding spectral densities, related to the absorption of radiation, have been considered for the first time using the present force field. In addition, structural properties such as density and pressure profiles, a deuterium-order parameter, surface tension, and the extent of water penetration in the membrane have been analyzed. Molecular self-diffusion, reorientational motions, and spectral densities of atomic species reveal a variety of time scales playing a role in membrane dynamics. The mechanisms of lipid motion strongly depend on the time scale considered, from fast ballistic translation at the scale of picoseconds (effective diffusion coefficients of the order of 10 −5 cm 2 /s) to diffusive flow of a few lipids forming nanodomains at the scale of hundreds of nanoseconds (diffusion coefficients of the order of 10 −8 cm 2 /s). In the intermediate regime of sub-diffusion, collisions with nearest neighbors prevent the lipids to achieve full diffusion. Lipid reorientations along selected directions agree well with reported nuclear magnetic resonance data and indicate two different time scales, one about 1 ns and a second one in the range of 2–8 ns. We associated the two time scales of reorientational motions with angular distributions of selected vectors. Calculated spectral densities corresponding to lipid and water reveal an overall good qualitative agreement with Fourier transform infrared spectroscopy experiments. Our simulations indicate a blue-shift of the low frequency spectral bands of hydration water as a result of its interaction

  5. Diffusion and spectroscopy of water and lipids in fully hydrated dimyristoylphosphatidylcholine bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J.; Martí, J., E-mail: jordi.marti@upc.edu [Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia (Spain); Calero, C. [Department of Physics and Nuclear Engineering, Technical University of Catalonia-Barcelona Tech, B4-B5 Northern Campus, Jordi Girona 1-3, 08034 Barcelona, Catalonia (Spain); Center for Polymer Studies, Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215 (United States)

    2014-03-14

    Microscopic structure and dynamics of water and lipids in a fully hydrated dimyristoylphosphatidylcholine phospholipid lipid bilayer membrane in the liquid-crystalline phase have been analyzed with all-atom molecular dynamics simulations based on the recently parameterized CHARMM36 force field. The diffusive dynamics of the membrane lipids and of its hydration water, their reorientational motions as well as their corresponding spectral densities, related to the absorption of radiation, have been considered for the first time using the present force field. In addition, structural properties such as density and pressure profiles, a deuterium-order parameter, surface tension, and the extent of water penetration in the membrane have been analyzed. Molecular self-diffusion, reorientational motions, and spectral densities of atomic species reveal a variety of time scales playing a role in membrane dynamics. The mechanisms of lipid motion strongly depend on the time scale considered, from fast ballistic translation at the scale of picoseconds (effective diffusion coefficients of the order of 10{sup −5} cm{sup 2}/s) to diffusive flow of a few lipids forming nanodomains at the scale of hundreds of nanoseconds (diffusion coefficients of the order of 10{sup −8} cm{sup 2}/s). In the intermediate regime of sub-diffusion, collisions with nearest neighbors prevent the lipids to achieve full diffusion. Lipid reorientations along selected directions agree well with reported nuclear magnetic resonance data and indicate two different time scales, one about 1 ns and a second one in the range of 2–8 ns. We associated the two time scales of reorientational motions with angular distributions of selected vectors. Calculated spectral densities corresponding to lipid and water reveal an overall good qualitative agreement with Fourier transform infrared spectroscopy experiments. Our simulations indicate a blue-shift of the low frequency spectral bands of hydration water as a result of

  6. The cellular environment of cancerous human tissue. Interfacial and dangling water as a "hydration fingerprint".

    Science.gov (United States)

    Abramczyk, Halina; Brozek-Pluska, Beata; Krzesniak, Marta; Kopec, Monika; Morawiec-Sztandera, Alina

    2014-08-14

    Despite a large number of publications, the role of water in the cellular environment of biological tissue has not been clarified. Characterizing the biological interface is a key challenge in understanding the interactions of water in the tissue. Although we often assume that the properties of the bulk water can be translated to the crowded biological environment, this approach must be considerably revised when considering the biological interface. To our knowledge, few studies have directly monitored the interactions and accumulation of water in the restricted environments of the biological tissue upon realistic crowding conditions. The present study focuses on a molecular picture of water molecules at the biological interface, or specifically, water molecules adjacent to the hydrophobic and hydrophilic surfaces of normal and cancerous tissues. We recorded and analyzed the IR and Raman spectra of the νs(OH) stretching modes of water at the biological interfaces of the human breast and neck tissues. The results revealed dramatic changes in the water content in the tissue and are potentially relevant to both the fundamental problems of interfacial water modeling and the molecular diagnostics of cancer as a 'hydration fingerprint'. Herein, we will discuss the origin of the vibrational substructures observed for the νs(OH) stretching modes of water, showing that the interfacial water interacting via H-bond with other water molecules and biomolecules at the biological surface and free OH vibration of the dangling water are sensitive indicators of the pathology between the normal (noncancerous) and cancerous tissue and cancer types. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. DFD-01 Reduces Transepidermal Water Loss and Improves Skin Hydration and Flexibility.

    Science.gov (United States)

    Jackson, J Mark; Grove, Gary L; Allenby, Kent; Houser, Tim

    2017-12-01

    In plaque psoriasis, the benefit of topical steroids is well established. The vehicle formulation of topical steroids may also provide benefit in addition to the effects of the steroid itself. DFD-01 (betamethasone dipropionate spray, 0.05%) is a formulation composed of a topical steroid in an emollient-like vehicle that enhances penetration to the target site of inflammation in the skin. The aim of this study was to assess the effect of DFD-01 and its vehicle on skin hydration and barrier function in compromised skin and to evaluate its effect on flexibility in healthy skin. Eighteen healthy white volunteers were enrolled in each of two studies. In Study 1, dry shaving of volar forearms created a compromised skin barrier, through which transepidermal water loss (TEWL) was measured using an evaporimeter. Capacitance, a measure of epidermal hydration, was also measured at baseline and at 1, 2 and 4 h after application of DFD-01 or its vehicle formulation. In Study 2, intact skin flexibility was tested with a cutometer before and at 1, 2 and 4 h after application of DFD-01 or vehicle. In Study 1, both DFD-01 and its vehicle were effective at reducing TEWL through the compromised stratum corneum. Capacitance measurements confirmed this finding; razor-chafed skin treated with either DFD-01 or vehicle exhibited levels of skin hydration similar to unshaved control skin. Study 2 found softening and greater flexibility of normal skin treated with either DFD-01 or vehicle compared with nontreated control skin samples. These tests suggest that the DFD-01 formulation and its vehicle are each effective at retaining moisture within a damaged skin barrier and for softening and increasing the flexibility of intact skin. Dr. Reddy's Laboratories.

  8. Total allowable concentrations of monomeric inorganic aluminum and hydrated aluminum silicates in drinking water.

    Science.gov (United States)

    Willhite, Calvin C; Ball, Gwendolyn L; McLellan, Clifton J

    2012-05-01

    Maximum contaminant levels are used to control potential health hazards posed by chemicals in drinking water, but no primary national or international limits for aluminum (Al) have been adopted. Given the differences in toxicological profiles, the present evaluation derives total allowable concentrations for certain water-soluble inorganic Al compounds (including chloride, hydroxide, oxide, phosphate and sulfate) and for the hydrated Al silicates (including attapulgite, bentonite/montmorillonite, illite, kaolinite) in drinking water. The chemistry, toxicology and clinical experience with Al materials are extensive and depend upon the particular physical and chemical form. In general, the water solubility of the monomeric Al materials depends on pH and their water solubility and gastrointestinal bioavailability are much greater than that of the hydrated Al silicates. Other than Al-containing antacids and buffered aspirin, food is the primary source of Al exposure for most healthy people. Systemic uptake of Al after ingestion of the monomeric salts is somewhat greater from drinking water (0.28%) than from food (0.1%). Once absorbed, Al accumulates in bone, brain, liver and kidney, with bone as the major site for Al deposition in humans. Oral Al hydroxide is used routinely to bind phosphate salts in the gut to control hyperphosphatemia in people with compromised renal function. Signs of chronic Al toxicity in the musculoskeletal system include a vitamin D-resistant osteomalacia (deranged membranous bone formation characterized by accumulation of the osteoid matrix and reduced mineralization, reduced numbers of osteoblasts and osteoclasts, decreased lamellar and osteoid bands with elevated Al concentrations) presenting as bone pain and proximal myopathy. Aluminum-induced bone disease can progress to stress fractures of the ribs, femur, vertebrae, humerus and metatarsals. Serum Al ≥100 µg/L has a 75-88% positive predictive value for Al bone disease. Chronic Al

  9. C-Phycocyanin protects against acute tributyltin chloride neurotoxicity by modulating glial cell activity along with its anti-oxidant and anti-inflammatory property: A comparative efficacy evaluation with N-acetyl cysteine in adult rat brain.

    Science.gov (United States)

    Mitra, Sumonto; Siddiqui, Waseem A; Khandelwal, Shashi

    2015-08-05

    Spirulina is a widely used health supplement and is a dietary source of C-Phycocyanin (CPC), a potent anti-oxidant. We have previously reported the neurotoxic potential of tributyltin chloride (TBTC), an environmental pollutant and potent biocide. In this study, we have evaluated the protective efficacy of CPC against TBTC induced neurotoxicity. To evaluate the extent of neuroprotection offered by CPC, its efficacy was compared with the degree of protection offered by N-acetylcysteine (NAC) (a well known neuroprotective drug, taken as a positive control). Male Wistar rats (28 day old) were administered with 20mg/kg TBTC (oral) and 50mg/kg CPC or 50mg/kg NAC (i.p.), alone or in combination, and various parameters were evaluated. These include blood-brain barrier (BBB) damage; redox parameters (ROS, GSH, redox pathway associated enzymes, oxidative stress markers); inflammatory, cellular, and stress markers; apoptotic proteins and in situ cell death assay (TUNEL). We observed increased CPC availability in cortical tissue following its administration. Although BBB associated proteins like claudin-5, p-glycoprotein and ZO-1 were restored, CPC/NAC failed to protect against TBTC induced overall BBB permeability (Evans blue extravasation). Both CPC and NAC remarkably reduced oxidative stress and inflammation. NAC effectively modulated redox pathway associated enzymes whereas CPC countered ROS levels efficiently. Interestingly, CPC and NAC were equivalently capable of reducing apoptotic markers, astroglial activation and cell death. This study illustrates the various pathways involved in CPC mediated neuroprotection against this environmental neurotoxicant and highlights its capability to modulate glial cell activity. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. Evaluation of Hydrate Inhibition Performance of Water-soluble Polymers using Torque Measurement and Differential Scanning Calorimeter

    International Nuclear Information System (INIS)

    Shin, Kyuchul; Park, Juwoon; Kim, Jakyung; Kim, Hyunho; Seo, Yutaek; Lee, Yohan; Seo, Yongwon

    2014-01-01

    In this work, hydrate inhibition performance of water-soluble polymers including pyrrolidone, caprolactam, acrylamide types were evaluated using torque measurement and high pressure differential scanning calorimeter (HP µ-DSC). The obtained experimental results suggest that the studied polymers represent the kinetic hydrate inhibition (KHI) performance. 0.5 wt% polyvinylcaprolactam (PVCap) solution shows the hydrate onset time of 34.4 min and subcooling temperature of 15.9 K, which is better KHI performance than that of pure water - hydrate onset time of 12.3 min and subcooling temperature of 6.0 K. 0.5 wt% polyvinylpyrrolidone (PVP) solution shows the hydrate onset time of 27.6 min and the subcooling temperature of 13.2 K while polyacrylamide-co-acrylic acid partial sodium salt (PAM-co-AA) solution shows less KHI performance than PVP solution at both 0.5 and 5.0 wt%. However, PAM-co-AA solution shows slow growth rate and low hydrate amount than PVCap. In addition to hydrate onset and growth condition, torque change with time was investigated as one of KHI evaluation methods. 0.5 wt% PVCap solution shows the lowest average torque of 6.4 N cm and 0.5 wt% PAM-co-AA solution shows the average torque of 7.2 N cm. For 0.5 wt% PVP solution, it increases 11.5 N cm and 5.0 wt% PAM-co-AA solution shows the maximum average torque of 13.4 N cm, which is similar to the average torque of pure water, 15.2 N cm. Judging from the experimental results obtained by both an autoclave and a HP µ-DSC, the PVCap solution shows the best performance among the KHIs in terms of delaying hydrate nucleation. From these results, it can be concluded that the torque change with time is useful to identify the flow ability of tested solution, and the further research on the inhibition of hydrate formation can be approached in various aspects using a HP µ-DSC

  11. The binding of the primary water of hydration to nucleosides, CsDNA and potassium hyaluronate

    Science.gov (United States)

    Lukan, A. M.; Cavanaugh, D.; Whitson, K. B.; Marlowe, R. L.; Lee, S. A.; Anthony, L.; Rupprecht, A.; Mohan, V.

    1998-03-01

    Differential scanning calorimetry (DSC) has been used to study the eight nucleosides, CsDNA and KHA hydrated at 59% relative humidity. Thermograms were measured between 25 and 180 ^oC for scan rates of 1, 2, 5, 10 and 20 K/min. A broad endothermic transition (due to the desorption of the water) near 80 ^oC was observed for all runs. The average enthalpy of desorption per water molecule was evaluated from the area under the peak. A Kissinger analysis of these data yielded the net activation energy for desorption. Both parameters were very similar for the two biopolymers. Rayleigh scattering of Mossbauer radiation (RSMR) data(G. Albanese et al. ) Hyperfine Int. 95, 97 (1995) were analyzed via a simple harmonic oscillator model to evaluate the effective force constant of the water bound to the biopolymer. This analysis suggests that the effective force constant of water bound to HA is much larger (about 5 times) than for water bound to DNA.

  12. Antioxidant activity of hydrated carboxylated nanodiamonds and its influence on water γ-radiolysis

    Science.gov (United States)

    Santacruz-Gomez, Karla; Sarabia-Sainz, A.; Acosta-Elias, M.; Sarabia-Sainz, M.; Janetanakit, Woraphong; Khosla, Nathan; Melendrez, R.; Pedroza Montero, Martin; Lal, Ratnesh

    2018-03-01

    Water radiolysis involves chemical decomposition of the water molecule into free radicals after exposure to ionizing radiation. These free radicals have deleterious effects on normal cell physiology. Carboxylated nanodiamonds (cNDs) appear to modulate the deleterious effects of γ-irradiation on the pathophysiology of red blood cells (RBCs). In the present work, the antioxidant activity of hydrated cNDs (h-cNDs) on limiting oxidative damage (the water radiolysis effect) by γ-irradiation was confirmed. Our results show that h-cNDs have remarkable free radical scavenging ability and preserve the enzymatic activity of catalase after γ-irradiation. The underlying mechanism through which nanodiamonds exhibit antioxidant activity appears to depend on their colloidal stability. This property of detonation synthesized nanodiamonds is improved after carboxylation, which in turn influences changes in the hydrogen bond strength in water. The observed stability of h-cNDs in water and their antioxidant activity correlates with their protective effect on RBCs against γ-irradiation.

  13. 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.

  14. Hydrated proton and hydroxide charge transfer at the liquid/vapor interface of water

    Energy Technology Data Exchange (ETDEWEB)

    Soniat, Marielle; Rick, Steven W., E-mail: srick@uno.edu [Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148 (United States); Kumar, Revati [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70808 (United States)

    2015-07-28

    The role of the solvated excess proton and hydroxide ions in interfacial properties is an interesting scientific question with applications in a variety of aqueous behaviors. The role that charge transfer (CT) plays in interfacial behavior is also an unsettled question. Quantum calculations are carried out on clusters of water with an excess proton or a missing proton (hydroxide) to determine their CT. The quantum results are applied to analysis of multi-state empirical valence bond trajectories. The polyatomic nature of the solvated excess proton and hydroxide ion results in directionally dependent CT, depending on whether a water molecule is a hydrogen bond donor or acceptor in relation to the ion. With polyatomic molecules, CT also depends on the intramolecular bond distances in addition to intermolecular distances. The hydrated proton and hydroxide affect water’s liquid/vapor interface in a manner similar to monatomic ions, in that they induce a hydrogen-bonding imbalance at the surface, which results in charged surface waters. This hydrogen bond imbalance, and thus the charged waters at the surface, persists until the ion is at least 10 Å away from the interface.

  15. Hydrated proton and hydroxide charge transfer at the liquid/vapor interface of water

    International Nuclear Information System (INIS)

    Soniat, Marielle; Rick, Steven W.; Kumar, Revati

    2015-01-01

    The role of the solvated excess proton and hydroxide ions in interfacial properties is an interesting scientific question with applications in a variety of aqueous behaviors. The role that charge transfer (CT) plays in interfacial behavior is also an unsettled question. Quantum calculations are carried out on clusters of water with an excess proton or a missing proton (hydroxide) to determine their CT. The quantum results are applied to analysis of multi-state empirical valence bond trajectories. The polyatomic nature of the solvated excess proton and hydroxide ion results in directionally dependent CT, depending on whether a water molecule is a hydrogen bond donor or acceptor in relation to the ion. With polyatomic molecules, CT also depends on the intramolecular bond distances in addition to intermolecular distances. The hydrated proton and hydroxide affect water’s liquid/vapor interface in a manner similar to monatomic ions, in that they induce a hydrogen-bonding imbalance at the surface, which results in charged surface waters. This hydrogen bond imbalance, and thus the charged waters at the surface, persists until the ion is at least 10 Å away from the interface

  16. On the densification and hydration of CaCO3 particles by Q-switched laser pulses in water

    Science.gov (United States)

    Lin, Peng-Wen; Wu, Chao-Hsien; Zheng, Yuyuan; Chen, Shuei-Yuan; Shen, Pouyan

    2013-09-01

    Calcite powders subjected to Q-switched laser pulses in water were characterized by X-ray/electron diffraction and optical spectroscopy to have a significant internal compressive stress (up to ca. 1.5 GPa) with accompanied transformation into defective calcite II and hydrates. The defective calcite II particles were (0 1 0), (0 0 1), (0 1¯ 1), (0 1 3) and (0 1¯ 3) faceted with 2×(0 2 0)II commensurate superstructure and tended to hydrate epitaxially as monohydrocalcite co-existing with ikaite (CaCO3·6H2O) with extensive cleavages and amorphous calcium carbonate with porous structure. The colloidal suspension containing the densified calcite polymorphs and hydrates showed two UV-visible absorptions corresponding to a minimum band gap of ca. 5 and 3 eV, respectively.

  17. Barley seed radiosensitivity following post-hydration in oxygen-, nitrogen- and nitrous oxide-saturated water, 1

    International Nuclear Information System (INIS)

    Singh, S.P.; Kesavan, P.C.

    1990-01-01

    Dry (∼3.5 and 4.0 per cent moisture content) barley seeds were exposed to 350 Gy of 60 Co-γ-rays in vacuo and post-hydrated at 4degC for 8 h in O 2 -, N 2 -, or N 2 O-saturated water. The effect of caffeine and t-butyl alcohol (t-BuOH) dissolved in the post-hydration medium on the magnitude of damage developing under these three different gaseous circumstances was studied. The post-irradiation damage and its modification by caffeine and t-BuOH was assessed in terms of 8-day-old seedling injury, peroxidase activity and total peroxides in the 8-day-old seedlings. Post-irradiation O 2 -saturated hydration caused maximal 8-day-old seedling injury, and increased peroxidase activity with concomitant reduction in total peroxides. Both caffeine and t-BuOH afforded significant radioprotection against post-irradiation O 2 -dependent damage. Post-irradiation N 2 O-saturated hydration was even more significantly radioprotective than the N 2 -saturated post-hydration. Under these circumstances, t-BuOH exerted no effect whatsoever on the N 2 - and N 2 O-mediated post-irradiation damage. Caffeine, on the other hand, significantly potentiated these two components of damage. A brief consideration of the physicochemical events which possibly account for the observed effects is presented. (author)

  18. 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.

  19. On the intermolecular vibrational coupling, hydrogen bonding, and librational freedom of water in the hydration shell of mono- and bivalent anions.

    Science.gov (United States)

    Ahmed, Mohammed; Namboodiri, V; Singh, Ajay K; Mondal, Jahur A

    2014-10-28

    The hydration energy of an ion largely resides within the first few layers of water molecules in its hydration shell. Hence, it is important to understand the transformation of water properties, such as hydrogen-bonding, intermolecular vibrational coupling, and librational freedom in the hydration shell of ions. We investigated these properties in the hydration shell of mono- (Cl(-) and I(-)) and bivalent (SO4(2-) and CO3(2-)) anions by using Raman multivariate curve resolution (Raman-MCR) spectroscopy in the OH stretch, HOH bend, and [bend+librational] combination bands of water. Raman-MCR of aqueous Na-salt (NaCl, NaI, Na2SO4, and Na2CO3) solutions provides ion-correlated spectra (IC-spectrum) which predominantly bear the vibrational characteristics of water in the hydration shell of respective anions. Comparison of these IC-spectra with the Raman spectrum of bulk water in different spectral regions reveals that the water is vibrationally decoupled with its neighbors in the hydration shell. Hydrogen-bond strength and librational freedom also vary with the nature of anion: hydrogen-bond strength, for example, decreases as CO3(2-) > SO4(2-) > bulk water ≈ Cl(-) > I(-); and the librational freedom increases as CO3(2-) ≈ SO4(2-) water water in the hydration shell of anions.

  20. Water flow in carbon-based nanoporous membranes impacted by interactions between hydrated ions and aromatic rings.

    Science.gov (United States)

    Liu, Jian; Shi, Guosheng; Fang, Haiping

    2017-02-24

    Carbon-based nanoporous membranes, such as carbon nanotubes (CNTs), graphene/graphene oxide and graphyne, have shown great potential in water desalination and purification, gas and ion separation, biosensors, and lithium-based batteries, etc. A deep understanding of the interaction between hydrated ions in an aqueous solution and the graphitic surface in systems composed of water, ions and a graphitic surface is essential for applications with carbon-based nanoporous membrane platforms. In this review, we describe the recent progress of the interaction between hydrated ions and aromatic ring structures on the carbon-based surface and its applications in the water flow in a carbon nanotube. We expect that these works can be extended to the understanding of water flow in other nanoporous membranes, such as nanoporous graphene, graphyne and stacked sheets of graphene oxide.

  1. Quantitative nanoscale water mapping in frozen-hydrated skin by low-loss electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yakovlev, Sergey [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Misra, Manoj; Shi, Shanling [Unilever Research and Development, Trumbull, CT 06611 (United States); Firlar, Emre [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Libera, Matthew, E-mail: mlibera@stevens.edu [Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ 07030 (United States)

    2010-06-15

    Spatially resolved low-loss electron energy-loss spectroscopy (EELS) is a powerful method to quantitatively determine the water distribution in frozen-hydrated biological materials at high spatial resolution. However, hydrated tissue, particularly its hydrophilic protein-rich component, is very sensitive to electron radiation. This sensitivity has traditionally limited the achievable spatial resolution because of the relatively high noise associated with low-dose data acquisition. We show that the damage caused by high-dose data acquisition affects the accuracy of a multiple-least-squares (MLS) compositional analysis because of inaccuracies in the reference spectrum used to represent the protein. Higher spatial resolution combined with more accurate compositional analysis can be achieved if a reference spectrum is used that better represents the electron-beam-damaged protein component under frozen-hydrated conditions rather than one separately collected from dry protein under low-dose conditions. We thus introduce a method to extract the best-fitting protein reference spectrum from an experimental spectrum dataset. This method can be used when the MLS-fitting problem is sufficiently constrained so that the only unknown is the reference spectrum for the protein component. We apply this approach to map the distribution of water in cryo-sections obtained from frozen-hydrated tissue of porcine skin. The raw spectral data were collected at doses up to 10{sup 5} e/nm{sup 2} despite the fact that observable damage begins at doses as low as 10{sup 3} e/nm{sup 2}. The resulting spatial resolution of 10 nm is 5-10 times better than that in previous studies of frozen-hydrated tissue and is sufficient to resolve sub-cellular water fluctuations as well as the inter-cellular lipid-rich regions of skin where water-mediated processes are believed to play a significant role in the phenotype of keratinocytes in the stratum corneum.

  2. Quantitative nanoscale water mapping in frozen-hydrated skin by low-loss electron energy-loss spectroscopy

    International Nuclear Information System (INIS)

    Yakovlev, Sergey; Misra, Manoj; Shi, Shanling; Firlar, Emre; Libera, Matthew

    2010-01-01

    Spatially resolved low-loss electron energy-loss spectroscopy (EELS) is a powerful method to quantitatively determine the water distribution in frozen-hydrated biological materials at high spatial resolution. However, hydrated tissue, particularly its hydrophilic protein-rich component, is very sensitive to electron radiation. This sensitivity has traditionally limited the achievable spatial resolution because of the relatively high noise associated with low-dose data acquisition. We show that the damage caused by high-dose data acquisition affects the accuracy of a multiple-least-squares (MLS) compositional analysis because of inaccuracies in the reference spectrum used to represent the protein. Higher spatial resolution combined with more accurate compositional analysis can be achieved if a reference spectrum is used that better represents the electron-beam-damaged protein component under frozen-hydrated conditions rather than one separately collected from dry protein under low-dose conditions. We thus introduce a method to extract the best-fitting protein reference spectrum from an experimental spectrum dataset. This method can be used when the MLS-fitting problem is sufficiently constrained so that the only unknown is the reference spectrum for the protein component. We apply this approach to map the distribution of water in cryo-sections obtained from frozen-hydrated tissue of porcine skin. The raw spectral data were collected at doses up to 10 5 e/nm 2 despite the fact that observable damage begins at doses as low as 10 3 e/nm 2 . The resulting spatial resolution of 10 nm is 5-10 times better than that in previous studies of frozen-hydrated tissue and is sufficient to resolve sub-cellular water fluctuations as well as the inter-cellular lipid-rich regions of skin where water-mediated processes are believed to play a significant role in the phenotype of keratinocytes in the stratum corneum.

  3. Determining the water-cement ratio, cement content, water content and degree of hydration of hardened cement paste: Method development and validation on paste samples

    International Nuclear Information System (INIS)

    Wong, H.S.; Buenfeld, N.R.

    2009-01-01

    We propose a new method to estimate the initial cement content, water content and free water/cement ratio (w/c) of hardened cement-based materials made with Portland cements that have unknown mixture proportions and degree of hydration. This method first quantifies the composition of the hardened cement paste, i.e. the volumetric fractions of capillary pores, hydration products and unreacted cement, using high-resolution field emission scanning electron microscopy (FE-SEM) in the backscattered electron (BSE) mode and image analysis. From the obtained data and the volumetric increase of solids during cement hydration, we compute the initial free water content and cement content, hence the free w/c ratio. The same method can also be used to calculate the degree of hydration. The proposed method has the advantage that it is quantitative and does not require comparison with calibration graphs or reference samples made with the same materials and cured to the same degree of hydration as the tested sample. This paper reports the development, assumptions and limitations of the proposed method, and preliminary results from Portland cement pastes with a range of w/c ratios (0.25-0.50) and curing ages (3-90 days). We also discuss the extension of the technique to mortars and concretes, and samples made with blended cements.

  4. Interaction of Simple Ions with Water: Theoretical Models for the Study of Ion Hydration

    Science.gov (United States)

    Gancheff, Jorge S.; Kremer, Carlos; Ventura, Oscar N.

    2009-01-01

    A computational experiment aimed to create and systematically analyze models of simple cation hydrates is presented. The changes in the structure (bond distances and angles) and the electronic density distribution of the solvent and the thermodynamic parameters of the hydration process are calculated and compared with the experimental data. The…

  5. Nuclear magnetic resonance study of diffusion and relaxation in hydrating white cement pastes of different water content

    International Nuclear Information System (INIS)

    Nestle, Nikolaus; Galvosas, Petrik; Geier, Oliver; Zimmermann, Christian; Dakkouri, Marwan; Karger, Jorg

    2001-01-01

    While the nuclear spin relaxation time changes in hydrating cement materials have been widely studied by various groups during the last 20 years, data on the self-diffusion behavior of the pore water during hydration of a cement paste are much scarcer. Taking advantage of improved spectrometer hardware for pulsed field gradient diffusometry and a specialized pulse sequence which is designed to compensate the detrimental effects of inner magnetic field gradients in the sample we have studied the water self-diffusion behavior in pastes prepared from white cement at various water/cement ratios. For the same mixtures, studies of the transverse spin relaxation behavior were also conducted. A comparison of the results from both techniques shows that the diffusion coefficient starts to decrease only much later than the relaxation times for all pastes studied. [copyright] 2001 American Institute of Physics

  6. A gas production system from methane hydrate layers by hot water injection and BHP control with radial horizontal wells

    Energy Technology Data Exchange (ETDEWEB)

    Yamakawa, T.; Ono, S.; Iwamoto, A.; Sugai, Y.; Sasaki, K. [Kyushu Univ., Fukuoka, Fukuoka (Japan)

    2010-07-01

    Reservoir characterization of methane hydrate (MH) bearing turbidite channel in the eastern Nankai Trough, in Japan has been performed to develop a gas production strategy. This paper proposed a gas production system from methane hydrate (MH) sediment layers by combining the hot water injection method and bottom hole pressure control at the production well using radial horizontal wells. Numerical simulations of the cylindrical homogeneous MH layer model were performed in order to evaluate gas production characteristics by the depressurization method with bottom hole pressure control. In addition, the effects of numerical block modeling and averaging physical properties of MH layers were presented. According to numerical simulations, combining the existing production system with hot water injection and bottom hole pressure control results in an outward expansion of the hot water chamber from the center of the MH layer with continuous gas production. 10 refs., 15 figs.

  7. Hydration water dynamics in biopolymers from NMR relaxation in the rotating frame.

    Science.gov (United States)

    Blicharska, Barbara; Peemoeller, Hartwig; Witek, Magdalena

    2010-12-01

    Assuming dipole-dipole interaction as the dominant relaxation mechanism of protons of water molecules adsorbed onto macromolecule (biopolymer) surfaces we have been able to model the dependences of relaxation rates on temperature and frequency. For adsorbed water molecules the correlation times are of the order of 10(-5)s, for which the dispersion region of spin-lattice relaxation rates in the rotating frame R(1)(ρ)=1/T(1)(ρ) appears over a range of easily accessible B(1) values. Measurements of T(1)(ρ) at constant temperature and different B(1) values then give the "dispersion profiles" for biopolymers. Fitting a theoretical relaxation model to these profiles allows for the estimation of correlation times. This way of obtaining the correlation time is easier and faster than approaches involving measurements of the temperature dependence of R(1)=1/T(1). The T(1)(ρ) dispersion approach, as a tool for molecular dynamics study, has been demonstrated for several hydrated biopolymer systems including crystalline cellulose, starch of different origins (potato, corn, oat, wheat), paper (modern, old) and lyophilized proteins (albumin, lysozyme). Copyright © 2010 Elsevier Inc. All rights reserved.

  8. [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.

  9. Differential Scanning Calorimetric Study and Potential Model of the Binding of the Primary Water of Hydration to K-Hyaluronate

    Science.gov (United States)

    Whitson, K. B.; Marlowe, R. L.; Lukan, A. M.; Lee, S. A.; Anthony, L.; Rupprecht, A.

    1997-11-01

    DSC was performed on samples of K-hyaluronate (KHA) through a temperature range of 25-180^oC. A transition peak was observed which is due to the desorption of the primary water of hydration. The maximum position of the peak was observed to change with different scan rates. The average energy of activation, E_A, and enthalpy for desorption of the primary water of hydration was determined to be 0.62 and 0.17 eV per water molecule, respectively. Analysis of Mossbauer data(G. Albanese et al., Hyperfine Int.,) 95, 97 (1995) allowed us to determine the effective force constant, k_eff, of the water bound to KHA to be approximately 19.4 eV/nm^2. The parameters E_A, ΔH,and k_eff allow us to construct a potential model for the primary water of hydration of KHA. Comparison of these parameters with the same parameters for HA and DNA with different counterions reveal that the energy of activation is similar, as well as the enthalpy change.

  10. Hydrophobic hydration of poly-N-isopropyl acrylamide: a matter of the mean energetic state of water

    Science.gov (United States)

    Bischofberger, I.; Calzolari, D. C. E.; de Los Rios, P.; Jelezarov, I.; Trappe, V.

    2014-03-01

    The enthalpically favoured hydration of hydrophobic entities, termed hydrophobic hydration, impacts the phase behaviour of numerous amphiphiles in water. Here, we show experimental evidence that hydrophobic hydration is strongly determined by the mean energetics of the aqueous medium. We investigate the aggregation and collapse of an amphiphilic polymer, poly-N-isopropyl acrylamide (PNiPAM), in aqueous solutions containing small amounts of alcohol and find that the thermodynamic characteristics defining the phase transitions of PNiPAM evolve relative to the solvent composition at which the excess mixing enthalpy of the water/alcohol mixtures becomes minimal. Such correlation between solvent energetics and solution thermodynamics extends to other mixtures containing neutral organic solutes that are considered as kosmotropes to induce a strengthening of the hydrogen bonded water network. This denotes the energetics of water as a key parameter controlling the phase behaviour of PNiPAM and identifies the excess mixing enthalpy of water/kosmotrope mixtures as a gauge of the kosmotropic effect on hydrophobic assemblies.

  11. 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.

  12. Beaufort Sea deep-water gas hydrate recovery from a seafloor mound in a region of widespread BSR occurrence

    Science.gov (United States)

    Hart, Patrick E.; Pohlman, John W.; Lorenson, T.D.; Edwards, Brian D.

    2011-01-01

    Gas hydrate was recovered from the Alaskan Beaufort Sea slope north of Camden Bay in August 2010 during a U.S. Coast Guard Cutter Healy expedition (USCG cruise ID HLY1002) under the direction of the U.S. Geological Survey (USGS). Interpretation of multichannel seismic (MCS) reflection data collected in 1977 by the USGS across the Beaufort Sea continental margin identified a regional bottom simulating reflection (BSR), indicating that a large segment of the Beaufort Sea slope is underlain by gas hydrate. During HLY1002, gas hydrate was sampled by serendipity with a piston core targeting a steep-sided bathymetric high originally thought to be an outcrop of older, exposed strata. The feature cored is an approximately 1100m diameter, 130 m high conical mound, referred to here as the Canning Seafloor Mound (CSM), which overlies the crest of a buried anticline in a region of sub-parallel compressional folds beneath the eastern Beaufort outer slope. An MCS profile shows a prominent BSR upslope and downslope from the mound. The absence of a BSR beneath the CSM and occurrence of gas hydrate near the summit indicates that free gas has migrated via deep-rooted thrust faults or by structural focusing up the flanks of the anticline to the seafloor. Gas hydrate recovered from near the CSM summit at a subbottom depth of about 5.7 meters in a water depth of 2538 m was of nodular and vein-filling morphology. Although the hydrate was not preserved, residual gas from the core liner contained >95% methane by volume when corrected for atmospheric contamination. The presence of trace C4+hydrocarbons (extrusion contributing to the development of the mound. Blister-like inflation of the seafloor caused by formation and accumulation of shallow hydrate lenses is also a likely factor in CSM growth. Pore water analysis shows the sulfate-methane transition to be very shallow (0-1 mbsf), also supporting an active high-flux interpretation. Pore water with chloride concentrations as low as 160 m

  13. Exploring the ab initio/classical free energy perturbation method: The hydration free energy of water

    International Nuclear Information System (INIS)

    Sakane, Shinichi; Yezdimer, Eric M.; Liu, Wenbin; Barriocanal, Jose A.; Doren, Douglas J.; Wood, Robert H.

    2000-01-01

    The ab initio/classical free energy perturbation (ABC-FEP) method proposed previously by Wood et al. [J. Chem. Phys. 110, 1329 (1999)] uses classical simulations to calculate solvation free energies within an empirical potential model, then applies free energy perturbation theory to determine the effect of changing the empirical solute-solvent interactions to corresponding interactions calculated from ab initio methods. This approach allows accurate calculation of solvation free energies using an atomistic description of the solvent and solute, with interactions calculated from first principles. Results can be obtained at a feasible computational cost without making use of approximations such as a continuum solvent or an empirical cavity formation energy. As such, the method can be used far from ambient conditions, where the empirical parameters needed for approximate theories of solvation may not be available. The sources of error in the ABC-FEP method are the approximations in the ab initio method, the finite sample of configurations, and the classical solvent model. This article explores the accuracy of various approximations used in the ABC-FEP method by comparing to the experimentally well-known free energy of hydration of water at two state points (ambient conditions, and 973.15 K and 600 kg/m3). The TIP4P-FQ model [J. Chem. Phys. 101, 6141 (1994)] is found to be a reliable solvent model for use with this method, even at supercritical conditions. Results depend strongly on the ab initio method used: a gradient-corrected density functional theory is not adequate, but a localized MP2 method yields excellent agreement with experiment. Computational costs are reduced by using a cluster approximation, in which ab initio pair interaction energies are calculated between the solute and up to 60 solvent molecules, while multi-body interactions are calculated with only a small cluster (5 to 12 solvent molecules). Sampling errors for the ab initio contribution to

  14. Hydration, phase separation and nonlinear rheology of temperature-sensitive water-soluble polymers

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Fumihiko; Koga, Tsuyoshi [Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510 (Japan); Kaneda, Isamu [Department of Food Science, Rakuno Gakuen University, Ebetsu, Hokkaido 069-8501 (Japan); Winnik, Francoise M, E-mail: ftanaka@phys.polym.kyoto-u.ac.jp [Department of Chemistry and Faculty of Pharmacy, University of Montreal, Montreal, H3C 3J7 (Canada)

    2011-07-20

    The collapse of a poly(N-isopropylacrylamide) (PNIPAM) chain upon heating and the phase diagrams of aqueous PNIPAM solutions with a very flat lower critical solution temperature (LCST) phase separation line are theoretically studied on the basis of cooperative dehydration (simultaneous dissociation of bound water molecules in a group of correlated sequence), and compared with the experimental observation of temperature-induced coil-globule transition by light scattering methods. The transition becomes sharper with the cooperativity parameter {sigma} of hydration. The reentrant coil-globule-coil transition and cononsolvency in a mixed solvent of water and methanol are also studied from the viewpoint of competitive hydrogen bonds between polymer-water and polymer-methanol. The downward shift of the cloud-point curves (LCST cononsolvency) with the mol fraction of methanol due to the competition is calculated and compared with the experimental data. Aqueous solutions of hydrophobically modified PNIPAM carrying short alkyl chains at both chain ends (telechelic PNIPAM) are theoretically and experimentally studied. The LCST of these solutions is found to shift downward along the sol-gel transition curve as a result of end-chain association (association-induced phase separation), and separate from the coil-globule transition line. Associated structures in the solution, such as flower micelles, mesoglobules, and higher fractal assembly, are studied by ultra small-angle neutron scattering with theoretical modeling of the scattering function. Dynamic-mechanical modulus, nonlinear stationary viscosity, and stress build-up in start-up shear flows of the associated networks are studied on the basis of the affine and non-affine transient network theory. The molecular conditions for thickening, strain hardening, and stress overshoot are found in terms of the nonlinear amplitude A of the chain tension and the tension-dissociation coupling constant g.

  15. A consistent and verifiable macroscopic model for the dissolution of liquid CO2 in water under hydrate forming conditions

    International Nuclear Information System (INIS)

    Radhakrishnan, R.; Demurov, A.; Trout, B.L.; Herzog, H.

    2003-01-01

    Direct injection of liquid CO 2 into the ocean has been proposed as one method to reduce the emission levels of CO 2 into the atmosphere. When liquid CO 2 is injected (normally as droplets) at ocean depths >500 m, a solid interfacial region between the CO 2 and the water is observed to form. This region consists of hydrate clathrates and hinders the rate of dissolution of CO 2 . It is, therefore, expected to have a significant impact on the injection of liquid CO 2 into the ocean. Up until now, no consistent and predictive model for the shrinking of droplets of CO 2 under hydrate forming conditions has been proposed. This is because all models proposed to date have had too many unknowns. By computing rates of the physical and chemical processes in hydrates via molecular dynamics simulations, we have been able to determine independently some of these unknowns. We then propose the most reasonable model and use it to make independent predictions of the rates of mass transfer and thickness of the hydrate region. These predictions are compared to measurements, and implications to the rates of shrinkage of CO 2 droplets under varying flow conditions are discussed. (author)

  16. A novel continuous colour mapping approach for visualization of facial skin hydration and transepidermal water loss for four ethnic groups.

    Science.gov (United States)

    Voegeli, R; Rawlings, A V; Seroul, P; Summers, B

    2015-12-01

    The aim of this exploratory study was to develop a novel colour mapping approach to visualize and interpret the complexity of facial skin hydration and barrier properties of four ethnic groups (Caucasians, Indians, Chinese and Black Africans) living in Pretoria, South Africa. We measured transepidermal water loss (TEWL) and skin capacitance on 30 pre-defined sites on the forehead, cheek, jaw and eye areas of sixteen women (four per ethnic group) and took digital images of their faces. Continuous colour maps were generated by interpolating between each measured value and superimposing the values on the digital images. The complexity of facial skin hydration and skin barrier properties is revealed by these measurements and visualized by the continuous colour maps of the digital images. Overall, the Caucasian subjects had the better barrier properties followed by the Black African subjects, Chinese subjects and Indian subjects. Nevertheless, the two more darkly pigmented ethnic groups had superior skin hydration properties. Subtle differences were seen when examining the different facial sites. There exists remarkable skin capacitance and TEWL gradients within short distances on selected areas of the face. These gradients are distinctive in the different ethnic groups. In contrast to other reports, we found that darkly pigmented skin does not always have a superior barrier function and differences in skin hydration values are complex on the different parts of the face among the different ethnic groups. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  17. Time-series measurements of bubble plume variability and water column methane distribution above Southern Hydrate Ridge, Oregon

    Science.gov (United States)

    Philip, Brendan T.; Denny, Alden R.; Solomon, Evan A.; Kelley, Deborah S.

    2016-03-01

    An estimated 500-2500 gigatons of methane carbon is sequestered in gas hydrate at continental margins and some of these deposits are associated with overlying methane seeps. To constrain the impact that seeps have on methane concentrations in overlying ocean waters and to characterize the bubble plumes that transport methane vertically into the ocean, water samples and time-series acoustic images were collected above Southern Hydrate Ridge (SHR), a well-studied hydrate-bearing seep site ˜90 km west of Newport, Oregon. These data were coregistered with robotic vehicle observations to determine the origin of the seeps, the plume rise heights above the seafloor, and the temporal variability in bubble emissions. Results show that the locations of seep activity and bubble release remained unchanged over the 3 year time-series investigation, however, the magnitude of gas release was highly variable on hourly time scales. Bubble plumes were detected to depths of 320-620 m below sea level (mbsl), in several cases exceeding the upper limit of hydrate stability by ˜190 m. For the first time, sustained gas release was imaged at the Pinnacle site and in-between the Pinnacle and the Summit area of venting, indicating that the subseafloor transport of fluid and gas is not restricted to the Summit at SHR, requiring a revision of fluid-flow models. Dissolved methane concentrations above background levels from 100 to 300 mbsl are consistent with long-term seep gas transport into the upper water column, which may lead to the build-up of seep-derived carbon in regional subsurface waters and to increases in associated biological activity.

  18. Hydration of DNA by tritiated water and isotope distribution: a study by 1H, 2H, and 3H NMR spectroscopy

    International Nuclear Information System (INIS)

    Mathur-De Vre, R.; Grimee-Declerck, R.; Lejeune, P.; Bertinchamps, A.J.

    1982-01-01

    The hydration layer of DNA (0.75%) in tritiated water represents 3.5% of solvent 3 HHO. The combined effects of temperature (-6 to -40 0 C) and H 2 O/ 2 H 2 O solvent composition on the spin-lattice relaxation times of water protons and deuterons suggest selective distribution of isotopes in the hydration layer. The ''hydration isotope'' effect and the localization of tritiated water molecules in the hydration layer of DNA have important implications in describing the radiobiological effects of tritiated water because the initial molecular damage caused by 3 HHO (internal radiation source) localizes close to 3 H due to the short range and low energy of 3 H β rays

  19. Development and preliminary testing of a standardized method for quantifying excess water in over-hydrated skin using evaporimetry

    International Nuclear Information System (INIS)

    Fader, M; Clark-O'Neill, S R; Cottenden, A M; Wong, W K R; Runeman, B; Farbrot, A

    2011-01-01

    Although evaporimetry (the measurement of water vapour flux density from the skin) has often been used to study the impact on skin hydration of using products such as baby diapers and incontinence pads, it is difficult to interpret results and to compare data from different studies because of the diversity of unvalidated methodologies used. The aim of this work was to develop a robust methodology for measuring the excess water in over-hydrated skin and test it on volar forearm and hip skin which had been occluded with saline soaked patches. Three repeat measurements were made on the volar forearm and the hip of five young (31–44 years) and six older (67–85 years) women and moderately good within-subject repeatability was found for both skin sites for both subject groups. Measurements taken from the hip were significantly higher (P = 0.001) than those from the arm and had larger coefficients of variation (3.5–22.1%) compared to arms (3.0–14.0%). There were no significant differences between young and older skin, implying that women for future studies could be recruited without regard to age. This is the first time that a robust evaporimetric methodology for quantifying excess water in over-hydrated skin has been described and validated, and it will form a solid basis for future work

  20. Studies on the crystal structure and arrangement of water in sitagliptin L-tartrate hydrates

    Czech Academy of Sciences Publication Activity Database

    Tieger, E.; Kiss, V.; Pokol, G.; Finta, Z.; Dušek, Michal; Rohlíček, Jan; Skořepová, E.; Brázda, Petr

    2016-01-01

    Roč. 18, č. 21 (2016), s. 3819-3831 ISSN 1466-8033 R&D Projects: GA MŠk LO1603; GA ČR GA16-10035S EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : sitagliptin tartarate * crystal structure * channel hydrates * hydration * dehydration Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.474, year: 2016

  1. Role of Aquaporin Water Channels in Airway Fluid Transport, Humidification, and Surface Liquid Hydration

    Science.gov (United States)

    Song, Yuanlin; Jayaraman, Sujatha; Yang, Baoxue; Matthay, Michael A.; Verkman, A.S.

    2001-01-01

    Several aquaporin-type water channels are expressed in mammalian airways and lung: AQP1 in microvascular endothelia, AQP3 in upper airway epithelia, AQP4 in upper and lower airway epithelia, and AQP5 in alveolar epithelia. Novel quantitative methods were developed to compare airway fluid transport–related functions in wild-type mice and knockout mice deficient in these aquaporins. Lower airway humidification, measured from the moisture content of expired air during mechanical ventilation with dry air through a tracheotomy, was 54–56% efficient in wild-type mice, and reduced by only 3–4% in AQP1/AQP5 or AQP3/AQP4 double knockout mice. Upper airway humidification, measured from the moisture gained by dry air passed through the upper airways in mice breathing through a tracheotomy, decreased from 91 to 50% with increasing ventilation from 20 to 220 ml/min, and reduced by 3–5% in AQP3/AQP4 knockout mice. The depth and salt concentration of the airway surface liquid in trachea was measured in vivo using fluorescent probes and confocal and ratio imaging microscopy. Airway surface liquid depth was 45 ± 5 μm and [Na+] was 115 ± 4 mM in wild-type mice, and not significantly different in AQP3/AQP4 knockout mice. Osmotic water permeability in upper airways, measured by an in vivo instillation/sample method, was reduced by ∼40% by AQP3/AQP4 deletion. In doing these measurements, we discovered a novel amiloride-sensitive isosmolar fluid absorption process in upper airways (13% in 5 min) that was not affected by aquaporin deletion. These results establish the fluid transporting properties of mouse airways, and indicate that aquaporins play at most a minor role in airway humidification, ASL hydration, and isosmolar fluid absorption. PMID:11382807

  2. Effect of hydration of sugar groups on adsorption of Quillaja bark saponin at air/water and Si/water interfaces.

    Science.gov (United States)

    Wojciechowski, Kamil; Orczyk, Marta; Marcinkowski, Kuba; Kobiela, Tomasz; Trapp, Marcus; Gutberlet, Thomas; Geue, Thomas

    2014-05-01

    Adsorption of a natural glycoside surfactant Quillaja bark saponin ("QBS", Sigma Aldrich 84510) was studied at the air/water and Si/water interfaces using a combination of surface pressure (SP), surface dilatational rheology, neutron reflectivity (NR), Infra-Red Attenuated Total Reflection Spectroscopy (IR ATR) and Quartz Crystal Microbalance (QCM). The adsorbed layers formed at the air/water interface are predominantly elastic, with the dilatational surface storage modulus reaching the maximum value of E'=184 mN/m. The NR results point to a strong hydration of the adsorbed layers (about 65% hydration, corresponding to about 60 molecules of water per one QBS molecule), most likely related to the presence of multiple sugar groups constituting the glycone part of the QBS molecules. With a layer thickness of 19 Å, the adsorbed amount obtained from NR seems largely underestimated in comparison to the value obtained from the surface tension isotherm. While this high extent of hydration does not prevent formation of dense and highly elastic layers at the air-water surface, QBS adsorption at the Si/water interface is much weaker. The adsorption isotherm of QBS on Si obtained from the QCM study reflects much lower affinity of highly hydrated and negatively charged saponin molecules to the Si/water interface. We postulate that at the air/water interface, QBS adsorbs through the triterpene aglycone moiety. In contrast, weak hydrogen bonding between the glycone part and the surface silanol groups of Si is responsible for QBS adsorption on more polar Si/water interface. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. δD values of hydrated volcanic glass : a potential record of ancient meteoric water and climate in New Zealand

    International Nuclear Information System (INIS)

    Shane, P.; Ingraham, N.

    2002-01-01

    Tephra beds that are well drained and have been buried by thin paleosols become hydrated within 2-3000 yr on reaction with meteoric waters. Hence, the absorbed water within silicic volcanic glass shards provides a potential record of δD values of ancient meteoric water. Such isotopic records have previously received little investigation. We demonstrate that 1.5-2 m thick tephra beds in central North Island, New Zealand, display uniform δD values vertically through their profiles and laterally up to 250 m in outcrop. Reproducibility is not influenced by grain size or age of the tephra. We obtained an average δD value of -48 ± 3 permille for water within the 1.8 ka Taupo Tephra. This is similar to the composition of present-day surface waters. δD values of -73 ± 2 and -60 ± 2 permille for the 25 ka Kawakawa and 30 ka Mangaone Tephra beds are significantly lower than present waters, indicating that they have been hydrated under different surficial conditions. This is consistent with other proxy paleoclimatic indicators that suggest a cooler, drier, and windier climate at the time of their eruption. Tephra beds are a potential source of paleoclimatic data in terrestrial environments that otherwise may lack proxy records. (author). 17 refs., 5 figs., 3 tabs

  4. Hydration states of clays followed by water and hydroxyls vibrational analyses in the near infrared: application to saponite and bentonite systems

    International Nuclear Information System (INIS)

    Rinnert, E.

    2004-01-01

    The study of the feasibility of a deep geological disposal facility conducted by ANDRA - the French national radioactive waste management agency -, requires the knowledge of water status and water content in clays. Thanks to an original lab-built device coupling vibrational spectroscopies and water adsorption isotherms, adsorbed water and clay's structure are described quantitatively and qualitatively. A multidisciplinary approach allows the description of hydration mechanisms and water molecules network in the inter lamellar space of synthetic saponites. The effects of density and nature of inter-foliar cations and the influence of temperature on hydration are presented. Using mechanisms and important parameters established on saponites, hydration of bentonite MX80 is carried out. In order to describe and quantify simultaneously two different water states, a simple but relevant method of spectra analysis was developed. (author)

  5. Exploring the role of water in molecular recognition: predicting protein ligandability using a combinatorial search of surface hydration sites

    Science.gov (United States)

    Vukovic, Sinisa; Brennan, Paul E.; Huggins, David J.

    2016-09-01

    The interaction between any two biological molecules must compete with their interaction with water molecules. This makes water the most important molecule in medicine, as it controls the interactions of every therapeutic with its target. A small molecule binding to a protein is able to recognize a unique binding site on a protein by displacing bound water molecules from specific hydration sites. Quantifying the interactions of these water molecules allows us to estimate the potential of the protein to bind a small molecule. This is referred to as ligandability. In the study, we describe a method to predict ligandability by performing a search of all possible combinations of hydration sites on protein surfaces. We predict ligandability as the summed binding free energy for each of the constituent hydration sites, computed using inhomogeneous fluid solvation theory. We compared the predicted ligandability with the maximum observed binding affinity for 20 proteins in the human bromodomain family. Based on this comparison, it was determined that effective inhibitors have been developed for the majority of bromodomains, in the range from 10 to 100 nM. However, we predict that more potent inhibitors can be developed for the bromodomains BPTF and BRD7 with relative ease, but that further efforts to develop inhibitors for ATAD2 will be extremely challenging. We have also made predictions for the 14 bromodomains with no reported small molecule K d values by isothermal titration calorimetry. The calculations predict that PBRM1(1) will be a challenging target, while others such as TAF1L(2), PBRM1(4) and TAF1(2), should be highly ligandable. As an outcome of this work, we assembled a database of experimental maximal K d that can serve as a community resource assisting medicinal chemistry efforts focused on BRDs. Effective prediction of ligandability would be a very useful tool in the drug discovery process.

  6. Exploring the role of water in molecular recognition: predicting protein ligandability using a combinatorial search of surface hydration sites.

    Science.gov (United States)

    Vukovic, Sinisa; Brennan, Paul E; Huggins, David J

    2016-09-01

    The interaction between any two biological molecules must compete with their interaction with water molecules. This makes water the most important molecule in medicine, as it controls the interactions of every therapeutic with its target. A small molecule binding to a protein is able to recognize a unique binding site on a protein by displacing bound water molecules from specific hydration sites. Quantifying the interactions of these water molecules allows us to estimate the potential of the protein to bind a small molecule. This is referred to as ligandability. In the study, we describe a method to predict ligandability by performing a search of all possible combinations of hydration sites on protein surfaces. We predict ligandability as the summed binding free energy for each of the constituent hydration sites, computed using inhomogeneous fluid solvation theory. We compared the predicted ligandability with the maximum observed binding affinity for 20 proteins in the human bromodomain family. Based on this comparison, it was determined that effective inhibitors have been developed for the majority of bromodomains, in the range from 10 to 100 nM. However, we predict that more potent inhibitors can be developed for the bromodomains BPTF and BRD7 with relative ease, but that further efforts to develop inhibitors for ATAD2 will be extremely challenging. We have also made predictions for the 14 bromodomains with no reported small molecule K d values by isothermal titration calorimetry. The calculations predict that PBRM1(1) will be a challenging target, while others such as TAF1L(2), PBRM1(4) and TAF1(2), should be highly ligandable. As an outcome of this work, we assembled a database of experimental maximal K d that can serve as a community resource assisting medicinal chemistry efforts focused on BRDs. Effective prediction of ligandability would be a very useful tool in the drug discovery process.

  7. PRODUCTION OF HYDRATED ELECTRONS FROM PHOTOIONIZATION OF DISSOLVED ORGANIC MATTER IN NATURAL WATERS

    Science.gov (United States)

    Under UV irradiation, an important primary photochemical reaction of colored dissolved organic matter (CDOM) is electron ejection, producing hydrated electrons (e-aq). The efficiency of this process has been studied in both fresh and seawater samples with both steady-state scave...

  8. Unexpected inhibition of CO2 gas hydrate formation in dilute TBAB solutions and the critical role of interfacial water structure

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ngoc N.; Nguyen, Anh V.; Nguyen, Khoi T.; Rintoul, Llew; Dang, Liem X.

    2016-12-01

    Gas hydrates formed under moderated conditions open up novel approaches to tackling issues related to energy supply, gas separation, and CO2 sequestration. Several additives like tetra-n-butylammonium bromide (TBAB) have been empirically developed and used to promote gas hydrate formation. Here we report unexpected experimental results which show that TBAB inhibits CO2 gas hydrate formation when used at minuscule concentration. We also used spectroscopic techniques and molecular dynamics simulation to gain further insights and explain the experimental results. They have revealed the critical role of water alignment at the gas-water interface induced by surface adsorption of tetra-n-butylammonium cation (TBA+) which gives rise to the unexpected inhibition of dilute TBAB solution. The water perturbation by TBA+ in the bulk is attributed to the promotion effect of high TBAB concentration on gas hydrate formation. We explain our finding using the concept of activation energy of gas hydrate formation. Our results provide a step toward to mastering the control of gas hydrate formation.

  9. Revealing the influence of water-cement ratio on the pore size distribution in hydrated cement paste by using cyclohexane

    Science.gov (United States)

    Bede, Andrea; Ardelean, Ioan

    2017-12-01

    Varying the amount of water in a concrete mix will influence its final properties considerably due to the changes in the capillary porosity. That is why a non-destructive technique is necessary for revealing the capillary pore distribution inside hydrated cement based materials and linking the capillary porosity with the macroscopic properties of these materials. In the present work, we demonstrate a simple approach for revealing the differences in capillary pore size distributions introduced by the preparation of cement paste with different water-to-cement ratios. The approach relies on monitoring the nuclear magnetic resonance transverse relaxation distribution of cyclohexane molecules confined inside the cement paste pores. The technique reveals the whole spectrum of pores inside the hydrated cement pastes, allowing a qualitative and quantitative analysis of different pore sizes. The cement pastes with higher water-to-cement ratios show an increase in capillary porosity, while for all the samples the intra-C-S-H and inter-C-S-H pores (also known as gel pores) remain unchanged. The technique can be applied to various porous materials with internal mineral surfaces.

  10. Effects of water activity and low molecular weight humectants on skin permeability and hydration dynamics - a double-blind, randomized and controlled study.

    Science.gov (United States)

    Albèr, C; Buraczewska-Norin, I; Kocherbitov, V; Saleem, S; Lodén, M; Engblom, J

    2014-10-01

    The mammalian skin is a barrier that effectively separates the water-rich interior of the body from the normally dryer exterior. Changes in the external conditions, for example ambient humidity, have been shown to affect the skin barrier properties. The prime objective of this study was to evaluate the effect of water activity of a topical formulation on skin hydration and permeability. A second objective was to gain more understanding on how two commonly used humectants, urea and glycerol, affect skin barrier function in vivo. Simple aqueous formulations were applied under occlusion to the volar forearm of healthy volunteers. Following 4-h exposure, skin water loss (by transepidermal water loss measurements), skin hydration (by Corneometry) and skin permeability (by time to vasodilation due to benzyl nicotinate exposure) were monitored. The results demonstrate that a relatively small change in the water activity of a topical formulation is sufficient to induce considerable effects on stratum corneum hydration and permeability to exogenous substances. Exposing the skin to high water activity leads to increased skin hydration and also increased permeability. Furthermore, urea and glycerol promote skin hydration and permeability even at reduced water activity of the applied formulation. These results highlight the importance of considering the water activity in topically applied formulations and the potential benefit of using humectants. The results may impact formulation optimization in how to facilitate skin hydration and to modify skin permeability by temporarily open and close the skin barrier. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  11. Models for the transport of low energy electrons in water and the yield of hydrated electrons at early times

    International Nuclear Information System (INIS)

    Brenner, D.J.; Miller, J.H.; Ritchie, R.H.; Bichsel, H.

    1985-01-01

    An insulator model with four experimental energy bands was used to fit the optical properties of liquid water and to extend these data to non-zero momentum transfer. Inelastic mean free paths derived from this dielectric response function provided the basic information necessary to degrade high energy electrons to the subexcitation energy domain. Two approaches for the transport of subexcitation electrons were investigated. (i) Gas phase cross sections were used to degrade subexcitation electrons to thermal energy and the thermalization lengths were scaled to unit density. (ii) Thermalization lengths were estimated by age-diffusion theory with a stopping power deduced from the data on liquid water and transport cross sections derived from elastic scattering in water vapor. Theoretical ranges were compared to recent experimental results. A stochastic model was used to calculate the rapid diffusion and reaction of hydrated electrons with other radiolysis products. The sensitivity of the calculated yields to the model assumptions and comparison with experimental data are discussed

  12. Quantitative analysis of the hydration of lithium salts in water using multivariate curve resolution of near-infrared spectra

    Energy Technology Data Exchange (ETDEWEB)

    Barba, M. Isabel [Group of Research in Applied Thermal Engineering-CREVER, Mechanical Engineering Dept. (Spain); Larrechi, M. Soledad, E-mail: mariasoledad.larrechi@urv.cat [Analytical and Organic Chemistry Dept., Universitat Rovira i Virgili, Tarragona (Spain); Coronas, Alberto [Group of Research in Applied Thermal Engineering-CREVER, Mechanical Engineering Dept. (Spain)

    2016-05-05

    The hydration process of lithium iodide, lithium bromide, lithium chloride and lithium nitrate in water was analyzed quantitatively by applying multivariate curve resolution alternating least squares (MCR-ALS) to their near infrared spectra recorded between 850 nm and 1100 nm. The experiments were carried out using solutions with a salt mass fraction between 0% and 72% for lithium bromide, between 0% and 67% for lithium nitrate and between 0% and 62% for lithium chloride and lithium iodide at 323.15 K, 333.15 K, 343.15 K and 353.15 K, respectively. Three factors were determined for lithium bromide and lithium iodide and two factors for the lithium chloride and lithium nitrate by singular value decomposition (SVD) of their spectral data matrices. These factors are associated with various chemical environments in which there are aqueous clusters containing the ions of the salts and non-coordinated water molecules. Spectra and concentration profiles of non-coordinated water and cluster aqueous were retrieved by MCR-ALS. The amount of water involved in the process of hydration of the various salts was quantified. The results show that the water absorption capacity increases in the following order LiI < LiBr < LiNO{sub 3} < LiCl. The salt concentration at which there is no free water in the medium was calculated at each one of the temperatures considered. The values ranged between 62.6 and 65.1% for LiBr, 45.5–48.3% for LiCl, 60.4–61.2% for LiI and 60.3–63.7% for LiNO{sub 3}. These values are an initial approach to determining the concentration as from which crystal formation is favored. - Highlights: • Quantitative analysis of the hydration of lithium salts in water. • The absorption capacity of the electrolytes in function of the salt is evaluated. • The lithium salt concentration is estimated when the crystal formation is favored.

  13. Quantitative analysis of the hydration of lithium salts in water using multivariate curve resolution of near-infrared spectra

    International Nuclear Information System (INIS)

    Barba, M. Isabel; Larrechi, M. Soledad; Coronas, Alberto

    2016-01-01

    The hydration process of lithium iodide, lithium bromide, lithium chloride and lithium nitrate in water was analyzed quantitatively by applying multivariate curve resolution alternating least squares (MCR-ALS) to their near infrared spectra recorded between 850 nm and 1100 nm. The experiments were carried out using solutions with a salt mass fraction between 0% and 72% for lithium bromide, between 0% and 67% for lithium nitrate and between 0% and 62% for lithium chloride and lithium iodide at 323.15 K, 333.15 K, 343.15 K and 353.15 K, respectively. Three factors were determined for lithium bromide and lithium iodide and two factors for the lithium chloride and lithium nitrate by singular value decomposition (SVD) of their spectral data matrices. These factors are associated with various chemical environments in which there are aqueous clusters containing the ions of the salts and non-coordinated water molecules. Spectra and concentration profiles of non-coordinated water and cluster aqueous were retrieved by MCR-ALS. The amount of water involved in the process of hydration of the various salts was quantified. The results show that the water absorption capacity increases in the following order LiI < LiBr < LiNO_3 < LiCl. The salt concentration at which there is no free water in the medium was calculated at each one of the temperatures considered. The values ranged between 62.6 and 65.1% for LiBr, 45.5–48.3% for LiCl, 60.4–61.2% for LiI and 60.3–63.7% for LiNO_3. These values are an initial approach to determining the concentration as from which crystal formation is favored. - Highlights: • Quantitative analysis of the hydration of lithium salts in water. • The absorption capacity of the electrolytes in function of the salt is evaluated. • The lithium salt concentration is estimated when the crystal formation is favored.

  14. Deep-Water Acoustic Anomalies from Methane Hydrate in the Bering Sea

    Science.gov (United States)

    Wood, Warren T.; Barth, Ginger A.; Scholl, David W.; Lebedeva-Ivanova, Nina

    2015-01-01

    A recent expedition to the central Bering Sea, one of the most remote locations in the world, has yielded observations confirming gas and gas hydrates in this deep ocean basin. Significant sound speed anomalies found using inversion of pre-stack seismic data are observed in association with variable seismic amplitude anomalies in the thick sediment column. The anomalously low sound speeds below the inferred base of methane hydrate stability indicate the presence of potentially large quantities of gas-phase methane associated with each velocity-amplitude anomaly (VAMP). The data acquired are of such high quality that quantitative estimates of the concentrations of gas hydrates in the upper few hundred meters of sediment are also possible, and analyses are under way to make these estimates. Several VAMPs were specifically targeted in this survey; others were crossed incidentally. Indications of many dozens or hundreds of these features exist throughout the portion of the Bering Sea relevant to the U.S. extended continental shelf (ECS) consistent with the United Nations Convention on the Law of the Sea. 

  15. Body composition and hydration status changes in male and female open-water swimmers during an ultra-endurance event.

    Science.gov (United States)

    Weitkunat, Tim; Knechtle, Beat; Knechtle, Patrizia; Rüst, Christoph Alexander; Rosemann, Thomas

    2012-01-01

    Body mass changes during ultra-endurance performances have been described for running, cycling and for swimming in a heated pool. The present field study of 20 male and 11 female open-water swimmers investigated the changes in body composition and hydration status during an ultra-endurance event. Body mass, both estimated fat mass and skeletal muscle mass, haematocrit, plasma sodium concentration ([Na+]) and urine specific gravity were determined. Energy intake, energy expenditure and fluid intake were estimated. Males experienced significant reductions in body mass (-0.5 %) and skeletal muscle mass (-1.1 %) (P 0.05). Changes in percent body fat, fat mass, and fat-free mass were heterogeneous and did not reach statistical significance (P > 0.05) between gender groups. Fluid intake relative to plasma volume was higher in females than in males during the ultra-endurance event. Compared to males, females' average increase in haematocrit was 3.3 percentage points (pp) higher, urine specific gravity decrease 0.1 pp smaller, and plasma [Na+] 1.3 pp higher. The observed patterns of fluid intake, changes in plasma volume, urine specific gravity, and plasma [Na+] suggest that, particularly in females, a combination of fluid shift from blood vessels to interstitial tissue, facilitated by skeletal muscle damage, as well as exercise-associated hyponatremia had occurred. To summarise, changes in body composition and hydration status are different in male compared to female open-water ultra-endurance swimmers.

  16. 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

  17. Influence of hydration water on CH3NH3PbI3 perovskite films prepared through one-step procedure.

    Science.gov (United States)

    Wang, Ziyi; Yuan, Sijian; Li, Dahai; Jin, Feng; Zhang, Rongjun; Zhan, Yiqiang; Lu, Ming; Wang, Songyou; Zheng, Yuxiang; Guo, Junpeng; Fan, Zhiyong; Chen, Liangyao

    2016-10-31

    Organic-inorganic perovskites were fabricated through a one-step procedure with different levels of hydration water in precursor solutions. The optical properties of CH3NH3PbI3 films were investigated through spectroscopic ellipsometry and photoluminescence measurements. With the measured optical constants, the efficiency limit of perovskite solar cells is predicted with a detailed balance model. By comparing the optical measurement to that of planar heterojunction solar cells, we conclude that the radiative efficiency and porosity of the perovskite film significantly influence the performance of perovskite solar cells. An optimized hydration-water concentration is obtained for the 3CH3NH3I:1PbAc2•xH2O precursor solution. The results can provide guidance for further optimization of the device performance of perovskite solar cells by utilizing hydration water.

  18. Distribution of B, Cl and Their Isotopes in Pore Waters Separated from Gas Hydrate Potential Areas, Offshore Southwestern Taiwan

    Directory of Open Access Journals (Sweden)

    Hung-Chun Chao Chen-Feng You

    2006-01-01

    Full Text Available Boron (B and chlorine (Cl are widely distributed on the Earth’s surface and show distinctive geochemical behaviors. Cl behaves rather conservatively in oceanic environments while B is an excess-volatile and its distribution is sensitive to sediment absorption and organic matter degradation. The distribution of B, Cl and their isotopes in pore waters provide useful information for distinguishing between shallow circulation and deep origin fluid sources. Thirty-six sediment cores 0 - 5 m in length were sampled from a foreland accretionary prism offshore Southwestern Taiwan where strong bottom simulating reflectors (BSRs and an abundance of mud diapirs were discovered. More than 350 pore water samples were separated and analyzed for B, Cl and other major ions. Four long cores were selected for B and Cl isotopic analysis. We found that the Cl in all cores varied less than 10%, suggesting no major hydrate dissolution or formation involvement at shallow depths in the study area. However, the B concentration changed greatly, ranging between 360 and 650 μM, indicating a possible sedimentary contribution during the early diagenesis stage. The B isotopic compositions were relatively depleted (~25 to 37‰ in these pore waters, implying the addition of sedimentary exchangeable B with low δ11B. The Cl isotopes showed rather large variations, more than 8‰, possibly related to the addition of deep situated fluids. In summary, the chemical and isotopic characteristics of pore waters separated from piston cores off Southwestern Taiwan suggest strong influence from organic matter degradation during diagenesis at shallow depths and the possible addition of deep fluids advecting through mud diapir channels at greater depths, causing a minor degree of hydrate dissolution / formation to occur at shallow depths. Further systematic investigation of pore waters δ18O and δD are needed in a future study.

  19. Investigation of Wyoming Bentonite Hydration in Dry to Water-Saturated Supercritical CO2: Implications for Caprock Integrity

    Science.gov (United States)

    Loring, J. S.; Chen, J.; Thompson, C.; Schaef, T.; Miller, Q. R.; Martin, P. F.; Ilton, E. S.; Qafoku, O.; Felmy, A. R.; Rosso, K. M.

    2012-12-01

    The effectiveness of geologic sequestration as an enterprise for CO2 storage depends partly on the reactivity of supercritical CO2 (scCO2) with caprock minerals. Injection of scCO2 will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Caprock formations have high concentrations of clay minerals, including expandable montmorillonites. Water-bearing scCO2 is highly reactive and capable of hydrating or dehydrating clays, possibly leading to porosity and permeability changes that directly impact caprock performance. Dehydration will cause montmorillonite clay minerals in caprocks to contract, thereby decreasing solid volume and possibly increasing caprock permeability and porosity. On the other hand, water intercalation will cause these clays to expand, thereby increasing solid volume and possibly leading to self-sealing of caprock fractures. Pacific Northwest National Laboratory's Carbon Sequestration Initiative is developing capabilities for studying wet scCO2-mineral reactions in situ. Here, we introduce novel in situ infrared (IR) spectroscopic instrumentation that enables quantitative titrations of reactant minerals with water in scCO2. Results are presented for the infrared spectroscopic titrations of Na-, Ca-, and Mg-saturated Wyoming betonites with water over concentrations ranging from zero to scCO2 saturated. These experiments were carried out at 50°C and 90 bar. Transmission IR spectroscopy was used to measure concentrations of water dissolved in the scCO2 or intercalated into the clays. The titration curves evaluated from the transmission-IR data are compared between the three types of clays to assess the effects of the cation on water partitioning. Single-reflection attenuated total reflection (ATR) IR spectroscopy was used to collect the spectrum of the clays as they hydrate at every total water concentration during the titration. Clay hydration is evidenced by

  20. Characterization of water in hydrated Bombyx mori silk fibroin fiber and films by 2H NMR relaxation and 13C solid state NMR.

    Science.gov (United States)

    Asakura, Tetsuo; Isobe, Kotaro; Kametani, Shunsuke; Ukpebor, Obehi T; Silverstein, Moshe C; Boutis, Gregory S

    2017-03-01

    The mechanical properties of Bombyx mori silk fibroin (SF), such as elasticity and tensile strength, change remarkably upon hydration. However, the microscopic interaction with water is not currently well understood on a molecular level. In this work, the dynamics of water molecules interacting with SF was studied by 2 H solution NMR relaxation and exchange measurements. Additionally, the conformations of hydrated [3- 13 C]Ala-, [3- 13 C]Ser-, and [3- 13 C]Tyr-SF fibers and films were investigated by 13 C DD/MAS NMR. Using an inverse Laplace transform algorithm, we were able to identify four distinct components in the relaxation times for water in SF fiber. Namely, A: bulk water outside the fiber, B: water molecules trapped weakly on the surface of the fiber, C: bound water molecules located in the inner surface of the fiber, and D: bound water molecules located in the inner part of the fiber were distinguishable. In addition, four components were also observed for water in the SF film immersed in methanol for 30s, while only two components for the film immersed in methanol for 24h. The effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and non-crystalline domains of 13 C selectively labeled SF, respectively, could be determined independently. Our measurements provide new insight relating the characteristics of water and the hydration structure of silk, which are relevant in light of current interest in the design of novel silk-based biomaterials. The mechanical properties of Bombyx mori silk fibroin (SF) change remarkably upon hydration. However, the microscopic interaction between SF and water is not currently well understood on a molecular level. We were able to identify four distinct components in the relaxation times for water in SF fiber by 2 H solution NMR relaxation and exchange measurements. In addition, the effects of hydration on the conformation of Ser and Tyr residues in the site-specific crystalline and

  1. 2H Solid-State NMR Analysis of the Dynamics and Organization of Water in Hydrated Chitosan

    Directory of Open Access Journals (Sweden)

    Fenfen Wang

    2016-04-01

    Full Text Available Understanding water–biopolymer interactions, which strongly affect the function and properties of biopolymer-based tissue engineering and drug delivery materials, remains a challenge. Chitosan, which is an important biopolymer for the construction of artificial tissue grafts and for drug delivery, has attracted extensive attention in recent decades, where neutralization with an alkali solution can substantially enhance the final properties of chitosan films cast from an acidic solution. In this work, to elucidate the effect of water on the properties of chitosan films, we investigated the dynamics and different states of water in non-neutralized (CTS-A and neutralized (CTS-N hydrated chitosan by mobility selective variable-temperature (VT 2H solid-state NMR spectroscopy. Four distinct types of water exist in all of the samples with regards to dynamic behavior. First, non-freezable, rigid and strongly bound water was found in the crystalline domain at low temperatures. The second component consists of weakly bound water, which is highly mobile and exhibits isotropic motion, even below 260 K. Another type of water undergoes well-defined 180° flips around their bisector axis. Moreover, free water is also present in the films. For the CTS-A sample in particular, another special water species were bounded to acetic acid molecules via strong hydrogen bonding. In the case of CTS-N, the onset of motions of the weakly bound water molecules at 260 K was revealed by 2H-NMR spectroscopy. This water is not crystalline, even below 260 K, which is also the major contribution to the flexibility of chitosan chains and thus toughness of materials. By contrast, such motion was not observed in CTS-A. On the basis of the 2H solid-state NMR results, it is concluded that the unique toughness of CTS-N mainly originates from the weakly bound water as well as the interactions between water and the chitosan chains.

  2. 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.

  3. 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...

  4. Exploring the conserved water site and hydration of a coiled-coil trimerisation motif: a MD simulation study.

    Science.gov (United States)

    Dolenc, Jozica; Baron, Riccardo; Missimer, John H; Steinmetz, Michel O; van Gunsteren, Wilfred F

    2008-07-21

    The solvent structure and dynamics around ccbeta-p, a 17-residue peptide that forms a parallel three-stranded alpha-helical coiled coil in solution, was analysed through 10 ns explicit solvent molecular dynamics (MD) simulations at 278 and 330 K. Comparison with two corresponding simulations of the monomeric form of ccbeta-p was used to investigate the changes of hydration upon coiled-coil formation. Pronounced peaks in the solvent density distribution between residues Arg8 and Glu13 of neighbouring helices show the presence of water bridges between the helices of the ccbeta-p trimer; this is in agreement with the water sites observed in X-ray crystallography experiments. Interestingly, this water site is structurally conserved in many three-stranded coiled coils and, together with the Arg and Glu residues, forms part of a motif that determines three-stranded coiled-coil formation. Our findings show that little direct correlation exists between the solvent density distribution and the temporal ordering of water around the trimeric coiled coil. The MD-calculated effective residence times of up to 40 ps show rapid exchange of surface water molecules with the bulk phase, and indicate that the solvent distribution around biomolecules requires interpretation in terms of continuous density distributions rather than in terms of discrete molecules of water. Together, our study contributes to understanding the principles of three-stranded coiled-coil formation.

  5. 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.

  6. 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.

  7. Direct phase coexistence molecular dynamics study of the phase equilibria of the ternary methane-carbon dioxide-water hydrate system.

    Science.gov (United States)

    Michalis, Vasileios K; Tsimpanogiannis, Ioannis N; Stubos, Athanassios K; Economou, Ioannis G

    2016-09-14

    Molecular dynamics simulation is used to predict the phase equilibrium conditions of a ternary hydrate system. In particular, the direct phase coexistence methodology is implemented for the determination of the three-phase coexistence temperature of the methane-carbon dioxide-water hydrate system at elevated pressures. The TIP4P/ice, TraPPE-UA and OPLS-UA forcefields for water, carbon dioxide and methane respectively are used, in line with our previous studies of the phase equilibria of the corresponding binary hydrate systems. The solubility in the aqueous phase of the guest molecules of the respective binary and ternary systems is examined under hydrate-forming conditions, providing insight into the predictive capability of the methodology as well as the combination of these forcefields to accurately describe the phase behavior of the ternary system. The three-phase coexistence temperature is calculated at 400, 1000 and 2000 bar for two compositions of the methane-carbon dioxide mixture. The predicted values are compared with available calculations with satisfactory agreement. An estimation is also provided for the fraction of the guest molecules in the mixed hydrate phase under the conditions examined.

  8. Absolute proton hydration free energy, surface potential of water, and redox potential of the hydrogen electrode from first principles: QM/MM MD free-energy simulations of sodium and potassium hydration

    Science.gov (United States)

    Hofer, Thomas S.; Hünenberger, Philippe H.

    2018-06-01

    The absolute intrinsic hydration free energy GH+,w a t ◦ of the proton, the surface electric potential jump χwa t ◦ upon entering bulk water, and the absolute redox potential VH+,w a t ◦ of the reference hydrogen electrode are cornerstone quantities for formulating single-ion thermodynamics on absolute scales. They can be easily calculated from each other but remain fundamentally elusive, i.e., they cannot be determined experimentally without invoking some extra-thermodynamic assumption (ETA). The Born model provides a natural framework to formulate such an assumption (Born ETA), as it automatically factors out the contribution of crossing the water surface from the hydration free energy. However, this model describes the short-range solvation inaccurately and relies on the choice of arbitrary ion-size parameters. In the present study, both shortcomings are alleviated by performing first-principle calculations of the hydration free energies of the sodium (Na+) and potassium (K+) ions. The calculations rely on thermodynamic integration based on quantum-mechanical molecular-mechanical (QM/MM) molecular dynamics (MD) simulations involving the ion and 2000 water molecules. The ion and its first hydration shell are described using a correlated ab initio method, namely resolution-of-identity second-order Møller-Plesset perturbation (RIMP2). The next hydration shells are described using the extended simple point charge water model (SPC/E). The hydration free energy is first calculated at the MM level and subsequently increased by a quantization term accounting for the transformation to a QM/MM description. It is also corrected for finite-size, approximate-electrostatics, and potential-summation errors, as well as standard-state definition. These computationally intensive simulations provide accurate first-principle estimates for GH+,w a t ◦, χwa t ◦, and VH+,w a t ◦, reported with statistical errors based on a confidence interval of 99%. The values obtained

  9. 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)

  10. 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

  11. The effect of mineral-based alkaline water on hydration status and the metabolic response to short-term anaerobic exercise

    Directory of Open Access Journals (Sweden)

    Jakub Chycki

    2017-04-01

    Full Text Available Previously it was demonstrated that mineralization and alkalization properties of mineral water are important factors influencing acid-base balance and hydration in athletes. The purpose of this study was to investigate the effects of drinking different types of water on urine pH, specific urine gravity, and post-exercise lactate utilization in response to strenuous exercise. Thirty-six male soccer players were divided into three intervention groups, consuming around 4.0 l/day of different types of water for 7 days: HM (n=12; highly mineralized water, LM (n=12; low mineralized water, and CON (n=12; table water. The athletes performed an exercise protocol on two occasions (before and after intervention. The exercise protocol consisted of 5 bouts of intensive 60-s (120% VO2max cycling separated by 60 s of passive rest. Body composition, urinalysis and lactate concentration were evaluated – before (t0, immediately after (t1, 5’ (t2, and 30’ (t3 after exercise. Total body water and its active transport (TBW – total body water / ICW – intracellular water / ECW – extracellular water showed no significant differences in all groups, at both occasions. In the post-hydration state we found a significant decrease of specific urine gravity in HM (1021±4.2 vs 1015±3.8 g/L and LM (1022±3.1 vs 1008±4.2 g/L. We also found a significant increase of pH and lactate utilization rate in LM. In conclusion, the athletes hydrated with alkaline, low mineralized water demonstrated favourable changes in hydration status in response to high-intensity interval exercise with a significant decrease of specific urine gravity, increased urine pH and more efficient utilization of lactate after supramaximal exercise.

  12. 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

  13. Properties of cyclodextrins. II. Preparation of a stable β-cyclodextrin hydrate and determination of its water content and enthalpy of solution in water from 15 to 30.deg

    NARCIS (Netherlands)

    Wiedenhof, N.; Lammers, J.N.J.J.

    1968-01-01

    The solubility of ß-cyclodextrin (ß-CD) in water has been measured by a refractive-index method at 15–30°. Evidence was obtained that the same, solid ß-CD hydrate phase is present in this temperature range. The formula of the hydrate was shown to be C42H70O35(12.0 ± 0.5)H20. A method for preparation

  14. 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

  15. 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.

  16. 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.)

  17. Diaminoethane adsorption and water substitution on hydrated TiO2: a thermochemical study based on first-principles calculations.

    Science.gov (United States)

    Hémeryck, Anne; Motta, Alessandro; Swiatowska, Jolanta; Pereira-Nabais, Catarina; Marcus, Philippe; Costa, Dominique

    2013-07-14

    Epoxy-amines are used as structural adhesives deposited on Ti. The amine adhesion to a Ti surface depends highly on the surface state (oxidation, hydroxylation). Amines may adsorb above preadsorbed water molecules or substitute them to bind directly to surface Ti(4+) Lewis acid sites. The adsorption of a model amine molecule, diaminoethane (DAE), on a model surface, hydrated TiO2-anatase (101) surface, is investigated using Density Functional Theory including Dispersive forces (DFT-D) calculations. DAE adsorption and water substitution by DAE are exothermic processes and turn nearly isoenergetic at high coverage with adsorption-substitution energies around -0.3 eV (including dispersion forces and ZPE). Complementary ab initio molecular dynamics studies also suggest that the formation of an amine-water interaction induces water desorption from the surface at room temperature, a preliminary step towards the amine-Ti bond formation. An atomistic thermodynamic approach is developed to evaluate the interfacial free energy balance of both processes (adsorption and substitution). The main contributions to the energetic balance are dispersive interactions between molecules and the surface on the exergonic side, translational and rotational entropic contributions on the endergonic one. The substitution process is stabilized by 0.55 eV versus the adsorption one when free solvation, rotational and vibrational energies are considered. The main contribution to this free energy gain is due to water solvation. The calculations suggest that in toluene solvent with a water concentration of 10(-4) M or less, a full DAE layer replaces a preadsorbed water layer for a threshold concentration of DAE ≥ 0.1 M.

  18. Crystal structures of hydrates of simple inorganic salts. III. Water-rich aluminium halide hydrates: AlCl3 · 15H2O, AlBr3 · 15H2O, AlI3 · 15H2O, AlI3 · 17H2O and AlBr3 · 9H2O.

    Science.gov (United States)

    Schmidt, Horst; Hennings, Erik; Voigt, Wolfgang

    2014-09-01

    Water-rich aluminium halide hydrate structures are not known in the literature. The highest known water content per Al atom is nine for the perchlorate and fluoride. The nonahydrate of aluminium bromide, stable pentadecahydrates of aluminium chloride, bromide and iodide, and a metastable heptadecahydrate of the iodide have now been crystallized from low-temperature solutions. The structures of these hydrates were determined and are discussed in terms of the development of cation hydration spheres. The pentadecahydrate of the chloride and bromide are isostructural. In AlI(3) · 15H2O, half of the Al(3+) cations are surrounded by two complete hydration spheres, with six H2O in the primary and 12 in the secondary. For the heptadecahydrate of aluminium iodide, this hydration was found for every Al(3+).

  19. 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.

  20. Naphthenic acids hydrates of gases: influence of the water/oil interface on the dispersing properties of an acidic crude oil; Acides naphteniques hydrates de gaz de l'interface eau/huile sur les proprietes dispersantes d'un brut acide

    Energy Technology Data Exchange (ETDEWEB)

    Arla, D.

    2006-01-15

    Nowadays, the development of offshore oil production under increasing water depths (high pressures and low temperatures) has led oil companies to focus on gas hydrates risks. Hydrates are crystals containing gas and water molecules which can plug offshore pipelines. It has been shown that some asphaltenic crude oils stabilize water-in-oil emulsions (W/O) during several months and exhibit very good anti-agglomerant properties avoiding hydrate plugs formation. In this work, we have studied the 'anti-hydrate' properties of a West African acidic crude oil called crude AH. This oil contains naphthenic acids, RCOOH hydrocarbons which are sensitive to both the pH and the salinity of the water phase.The emulsifying properties of the crude AH have firstly been explored. It has been shown that heavy resins and asphaltenes are the main compounds of the crude AH responsible for the long term stability of the W/O emulsions whereas the napthenates RCOO{sup -} lead to less stable W/O emulsions. Dealing with hydrates, the crude AH exhibits moderate anti-agglomerant properties due to the presence of heavy resins and asphaltenes. However, the naphthenates RCOO{sup -} drastically increase the formation of hydrate plugs. Moreover, it has been pointed out that hydrate particles agglomeration accelerates the kinetics of hydrate formation and enhances the water/oil separation. In order to explain these behaviours, a mechanism of agglomeration by 'sticking' between a hydrate particle and a water droplet has been proposed. Finally, we have developed a model which describes the physico-chemical equilibria of the naphthenic acids in the binary system water/crude AH, in order to transpose the results obtained in the laboratory to the real oil field conditions. (author)

  1. The effects of silica fume and hydrated lime on the strength development and durability characteristics of concrete under hot water curing condition

    Directory of Open Access Journals (Sweden)

    Hamza Ali

    2017-01-01

    Full Text Available Sustainability is considered to be highly important for preserving continued industrial growth and human development. Concrete, being the world’s largest manufacturing material comprises cement as an essential binding component for strength development. However, excessive production of cement due to high degree of construction practices around the world frames cement as a leading pollutant of releasing significant amounts of CO2 in the atmosphere. To overcome this environmental degradation, silica fume and hydrated lime are used as partial replacements to cement. This paper begins with the examination of the partial replacement levels of hydrated lime and silica fume in concrete and their influence on the mechanical properties and durability characteristics of concrete. The effect of hot water curing on concrete incorporated with both silica fume and hydrated lime is also investigated in this paper. The results reported in this paper show that the use of silica fume as a partial replacement material improved both the mechanical properties and durability characteristics of concrete due to the formation of calcium silica hydrate crystals through the pozzolanic reaction. Although the hydrated lime did not significantly contribute in the development of strength, its presence enhanced the durability of concrete especially at long-term. The results also showed that hot water curing enhanced the strength development of concrete incorporated with silica fume due to the accelerated rate of both the hydration and pozzolanic reaction that takes place between silica fume and calcium hydroxide of the cement matrix particularly at early times. The results reported in this paper have significant contribution in the development of sustainable concrete. The paper does not only address the use of alternative binders as a partial replacement material in concrete but also suggest proper curing conditions for the proposed replacement materials. These practices

  2. Binding of the water of primary hydration to the sodium and cesium salts of deoxyribonucleic acid and potassium hyaluronate

    Science.gov (United States)

    Whitson, K. B.; Lukan, A. M.; Marlowe, R. L.; Lee, S. A.; Anthony, L.; Rupprecht, A.

    1998-08-01

    Differential scanning calorimetry (DSC) has been used to evaluate the average enthalpy of desorption of the water of primary hydration bound to wet-spun films of potassium hyaluronate (KHA) and CsDNA. The enthalpies were measured to be 0.24+/-0.08 eV/H2O molecule for KHA and 0.32+/-0.10 eV/H2O molecule for CsDNA. A Kissinger analysis was used to extract the net activation energy (0.61+/-0.04 eV) for the desorption of this water from KHA by analyzing DSC data acquired at different heating rates. The average effective force constants at 295 K of this water bound to KHA (63+/-3 μdyn/Å) and NaDNA (17+/-4 μdyn/Å) are determined from Rayleigh scattering of Mossbauer radiation data [G. Albanese, A. Deriu, F. Cavatorta, and A. Rupprecht, Hyperfine Interact. 95, 97 (1995)] via a harmonic approximation.

  3. 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...

  4. Chloral Hydrate

    Science.gov (United States)

    ... if you are allergic to chloral hydrate, aspirin, tartrazine (a yellow dye in some processed foods and ... in, tightly closed, and out of reach of children. Store it at room temperature, away from excess ...

  5. Hydrophobic hydration and anomalous excess partial molar volume of tert-butyl alcohol-water mixture studied by quasielastic neutron scattering

    International Nuclear Information System (INIS)

    Nakada, Masaru; Maruyama, Kenji; Misawa, Masakatsu; Yamamuro, Osamu

    2007-01-01

    Quasielastic neutron scattering has been used to investigate the hydration of alcohol clusters in tert-butyl alcohol-water mixture. The measurements were made in a range of alcohol concentration, x TBA , from 0.0 to 0.17 in mole fraction at 25degC. Fraction, α, of water molecules hydrated to fractal-surface of alcohol clusters in tert-butyl alcohol-water mixture was obtained as a function of alcohol concentration. Average hydration number N WS of tert-butyl alcohol molecule was derived from the value of α as a function of alcohol concentration. The value of N WS for an isolated alcohol molecule in water was 19-21. The anomalous excess partial molar volume of tert-butyl alcohol-water mixture was interpreted successfully by applying the same model with the same values of volume parameter as used for 1-propanol-water mixture, δ 1 (=-0.36 cm 3 ·mol -1 ) and δ 2 (=0.60 cm 3 ·mol -1 ). (author)

  6. Sensitivity of hydrogen bonds of DNA and RNA to hydration, as gauged by 1JNH measurements in ethanol-water mixtures

    International Nuclear Information System (INIS)

    Manalo, Marlon N.; Kong Xiangming; LiWang, Andy

    2007-01-01

    Hydrogen-bond lengths of nucleic acids are (1) longer in DNA than in RNA, and (2) sequence dependent. The physicochemical basis for these variations in hydrogen-bond lengths is unknown, however. Here, the notion that hydration plays a significant role in nucleic acid hydrogen-bond lengths is tested. Watson-Crick N1...N3 hydrogen-bond lengths of several DNA and RNA duplexes are gauged using imino 1 J NH measurements, and ethanol is used as a cosolvent to lower water activity. We find that 1 J NH values of DNA and RNA become less negative with added ethanol, which suggests that mild dehydration reduces hydrogen-bond lengths even as the overall thermal stabilities of these duplexes decrease. The 1 J NH of DNA are increased in 8 mol% ethanol to those of RNA in water, which suggests that the greater hydration of DNA plays a significant role in its longer hydrogen bonds. The data also suggest that ethanol-induced dehydration is greater for the more hydrated G:C base pairs and thereby results in greater hydrogen-bond shortening than for the less hydrated A:T/U base pairs of DNA and RNA

  7. 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

  8. 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.

  9. Hydration of alcohol clusters in 1-propanol-water mixture studied by quasielastic neutron scattering and an interpretation of anomalous excess partial molar volume.

    Science.gov (United States)

    Misawa, M; Inamura, Y; Hosaka, D; Yamamuro, O

    2006-08-21

    Quasielastic neutron scattering measurements have been made for 1-propanol-water mixtures in a range of alcohol concentration from 0.0 to 0.167 in mole fraction at 25 degrees C. Fraction alpha of water molecules hydrated to fractal surface of alcohol clusters in 1-propanol-water mixture was obtained as a function of alcohol concentration. Average hydration number N(ws) of 1-propanol molecule is derived from the value of alpha as a function of alcohol concentration. By extrapolating N(ws) to infinite dilution, we obtain values of 12-13 as hydration number of isolated 1-propanol molecule. A simple interpretation of structural origin of anomalous excess partial molar volume of water is proposed and as a result a simple equation for the excess partial molar volume is deduced in terms of alpha. Calculated values of the excess partial molar volumes of water and 1-propanol and the excess molar volume of the mixture are in good agreement with experimental values.

  10. Thermodynamic insight into spontaneous hydration and rapid water permeation in aquaporins

    Energy Technology Data Exchange (ETDEWEB)

    Barati Farimani, A.; Aluru, N. R. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Tajkhorshid, Emad [Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Department of Biochemistry and Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2014-08-25

    We report here a detailed thermodynamic description of water molecules inside a biological water channel. Taking advantage of high-resolution molecular dynamics trajectories calculated for an aquaporin (AQP) channel, we compute the spatial translational and rotational components of water diffusion and entropy in AQP. Our results reveal that the spontaneous filling and entry of water into the pore in AQPs are driven by an entropic gain. Specifically, water molecules exhibit an elevated degree of rotational motion inside the pore, while their translational motion is slow compared with bulk. The partial charges of the lining asparagine residues at the conserved signature Asn-Pro-Ala motifs play a key role in enhancing rotational diffusion and facilitating dipole flipping of water inside the pore. The frequencies of the translational and rotational motions in the power spectra overlap indicating a strong coupling of these motions in AQPs. A shooting mechanism with diffusive behavior is observed in the extracellular region which might be a key factor in the fast conduction of water in AQPs.

  11. A new combined nanoSIMS and continuous-flow IRMS approach to measure hydrogen isotopes from water in hydrated rhyolitic glass

    Science.gov (United States)

    Gatti, E.; Kitchen, N.; Newman, S.; Guan, Y.; Westgate, J.; Pearce, N. J. G.; Nikolic, D.; Eiler, J. M.

    2016-12-01

    The hydrogen-isotope value of water of hydration (or secondary water) preserved in rhyolitic glasses may provide significant insights regarding the climate at the time of their deposition and the impact of super-eruptions upon the environment. However, the ability of the glass to retain the environmental D/H isotopic signal after hydration needs to be tested, since modifications to the D/H systematics may result from the continuous exchange of D/H with the atmosphere or condensed water after initial glass hydration. Ideal geological archives to test whether the glass retains its original hydrogen signal are sediments in natural waters and ice cores, which preserve tephra in constrained horizons that can be independently isotopically characterised. However, tephra in marine and fresh water sediments and ice cores are often present in concentrations of the order of 1000 grains/cm3 (IRMS methods require much more material ( 100-500 mg) and therefore cannot be applied. We present here a new integrated nanoSIMS and continuous flow IRMS approach to understand how water is distributed within single glass grains (diffusion profiles), quantify the time of hydration of young (Holocene) and old (Miocene) already well-characterised rhyolitic glasses, and measure the D/H ratio of the hydration water on single grains and bulk material consisting of only approximately 0.1-1 mg. The IRMS method measures the absolute abundance of hydrogen released from the sample by continuous-flow mass spectrometry. Current data indicates that the method can accurately measure a hydrogen signal from a rock sample containing at least 400 nanomoles of H2, corresponding to 70 µg of water, which translates to 1 mg of hydrous glass (>3 wt%) or 15 mg of dry ( 0.5 wt%) obsidian chips. The method can be improved by reducing the blank to IRMS method will be compared to sub-micron mapping of single-grains using a high-resolution ion microprobe, the CAMECA NanoSIMS 50L, in the Microanalysis Center for

  12. Binding of Divalent Cations to Polygalacturonate: A Mechanism Driven by the Hydration Water.

    Science.gov (United States)

    Huynh, Uyen T D; Lerbret, Adrien; Neiers, Fabrice; Chambin, Odile; Assifaoui, Ali

    2016-02-11

    We have investigated the interactions between polygalacturonate (polyGal) and four divalent cations (M(2+) = Ba(2+), Ca(2+), Mg(2+), Zn(2+)) that differ in size and affinity for water. Our results evidence that M(2+)-polyGal interactions are intimately linked to the affinity of M(2+) for water. Mg(2+) interacts so strongly with water that it remains weakly bound to polyGal (polycondensation) by sharing water molecules from its first coordination shell with the carboxylate groups of polyGal. In contrast, the other cations form transient ionic pairs with polyGal by releasing preferentially one water molecule (for Zn(2+)) or two (for Ca(2+) and Ba(2+)), which corresponds to monodentate and bidentate binding modes with carboxylates, respectively. The mechanism for the binding of these three divalent cations to polyGal can be described by two steps: (i) monocomplexation and formation of point-like cross-links between polyGal chains (at low M(2+)/Gal molar ratios, R) and (ii) dimerization (at higher R). The threshold molar ratio, R*, between these two steps depends on the nature of divalent cations and is lower for calcium ions (R* 0.3). This difference may be explained by the intermediate affinity of Ca(2+) for water with respect to those of Zn(2+) and Ba(2+), which may induce the formation of cross-links of intermediate flexibility. By comparison, the lower and higher flexibilities of the cross-links formed by Zn(2+) and Ba(2+), respectively, may shift the formation of dimers to higher molar ratios (R*).

  13. The energy of hydration and solvation of indium salts in the acetylacetone-InCl3-water system

    International Nuclear Information System (INIS)

    Kulawik, I.; Baumgartner, T.

    1978-01-01

    On the base of the previous papers concerning the investigations in the extraction systems the experiments were performed for the determination of thermodynamical distribution coefficient of indium salts between two phases in the system: acetylacetone-InCl 3 -water and the energy of hydration and solvation of that system. The results of the surface and interfacial potentials measurements of the system were presented as a function of the InCl 3 concentration in the system before the extraction. The extraction coefficients of indium as a function of concentration of InCl 3 in this system were determined. The method of the visible absorption spectra was used to the determination of concentration of indium in both phases after the extraction. The relation between the percentage of the extraction and the extraction coefficient was determined. The investigations were performed in the system containing 0.1 M HCl and 0.001 M HCl in the aqueous phase. The results of experiments are tabulated and graphically presented in figures. (author)

  14. Proton affinities in water of maingroup-element Hydrides - Effects of hydration and methyl substitution

    NARCIS (Netherlands)

    Swart, M.; Rosler, E.; Bickelhaupt, F.M.

    2007-01-01

    We have computed the proton affinities in water of archetypal anionic and neutral bases across the periodic table using the generalized gradient approximation (GGA) of density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. The main purpose of this work is to provide an intrinsically consistent set

  15. 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

  16. An Evaluation of Common Cleaning Methods for the Removal of a Clinical Isolate of Escherichia coli in Personal Hydration System Water Reservoirs.

    Science.gov (United States)

    Helmus, Stephanie; Blythe, Jauchia; Guevara, Peter; Washington, Michael A

    2016-01-01

    Waterborne infection is an important cause of morbidity and mortality throughout the world. Personal hydration packs have been used by military personnel since the Gulf War and are now a common issue item. Since military personnel tend to operate under austere conditions and may use a variety of water sources, preventing the acquisition of waterborne infections is extremely important. Further, since hydration pack water reservoir replacements may not be available during combat operations, the development of a reliable cleaning protocol for use in the field is essential. Several methods for cleaning have been described. In the current study, three common cleaning methodologies-bleach treatment, baking soda treatment, and proprietary CAMELBAK Cleaning Tabs™-were evaluated for the ability to remove Escherichia coli contamination from hydration pack water reservoirs. The study results suggest that the use of bleach and proprietary CAMELBAK tablets should be encouraged since they both operate by releasing bactericidal chlorine compounds into solution, which is more effective at reducing post-treatment bacterial burden. It should be noted that no method was 100% effective at completely eliminating bacteria from the reservoirs and that mechanical cleaning was not attempted. 2016.

  17. Electrochemical monitoring of the co-extraction of water with hydrated ions into an organic solvent

    Czech Academy of Sciences Publication Activity Database

    Mareček, Vladimír

    2018-01-01

    Roč. 88, MAR 2018 (2018), s. 57-60 ISSN 1388-2481 R&D Projects: GA ČR(CZ) GA17-09980S Institutional support: RVO:61388955 Keywords : Liquid/liquid interface * Water co-extraction dynamics * Emulsification Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 4.396, year: 2016

  18. Barley seed radiosensitivity following post-hydration in oxygen-, nitrogen- and nitrous oxide-saturated water, 1; Influence of caffeine and t-butyl alcohol

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.P.; Kesavan, P.C. (Jawaharlal Nehru Univ., New Delhi (India). School of Life Sciences)

    1990-06-01

    Dry ({approx}3.5 and 4.0 per cent moisture content) barley seeds were exposed to 350 Gy of {sup 60}Co-{gamma}-rays in vacuo and post-hydrated at 4degC for 8 h in O{sub 2}-, N{sub 2}-, or N{sub 2}O-saturated water. The effect of caffeine and t-butyl alcohol (t-BuOH) dissolved in the post-hydration medium on the magnitude of damage developing under these three different gaseous circumstances was studied. The post-irradiation damage and its modification by caffeine and t-BuOH was assessed in terms of 8-day-old seedling injury, peroxidase activity and total peroxides in the 8-day-old seedlings. Post-irradiation O{sub 2}-saturated hydration caused maximal 8-day-old seedling injury, and increased peroxidase activity with concomitant reduction in total peroxides. Both caffeine and t-BuOH afforded significant radioprotection against post-irradiation O{sub 2}-dependent damage. Post-irradiation N{sub 2}O-saturated hydration was even more significantly radioprotective than the N{sub 2}-saturated post-hydration. Under these circumstances, t-BuOH exerted no effect whatsoever on the N{sub 2}- and N{sub 2}O-mediated post-irradiation damage. Caffeine, on the other hand, significantly potentiated these two components of damage. A brief consideration of the physicochemical events which possibly account for the observed effects is presented. (author).

  19. 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.

  20. Distinct role of hydration water in protein misfolding and aggregation revealed by fluctuating thermodynamics analysis.

    Science.gov (United States)

    Chong, Song-Ho; Ham, Sihyun

    2015-04-21

    Protein aggregation in aqueous cellular environments is linked to diverse human diseases. Protein aggregation proceeds through a multistep process initiated by conformational transitions, called protein misfolding, of monomer species toward aggregation-prone structures. Various forms of aggregate species are generated through the association of misfolded monomers including soluble oligomers and amyloid fibrils. Elucidating the molecular mechanisms and driving forces involved in the misfolding and subsequent association has been a central issue for understanding and preventing protein aggregation diseases such as Alzheimer's, Parkinson's, and type II diabetes. In this Account, we provide a thermodynamic perspective of the misfolding and aggregation of the amyloid-beta (Aβ) protein implicated in Alzheimer's disease through the application of fluctuating thermodynamics. This approach "dissects" the conventional thermodynamic characterization of the end states into the one of the fluctuating processes connecting them, and enables one to analyze variations in the thermodynamic functions that occur during the course of protein conformational changes. The central quantity in this approach is the solvent-averaged effective energy, f = Eu + Gsolv, comprising the protein potential energy (Eu) and the solvation free energy (Gsolv), whose time variation reflects the protein dynamics on the free energy landscape. Protein configurational entropy is quantified by the magnitude of fluctuations in f. We find that misfolding of the Aβ monomer when released from a membrane environment to an aqueous phase is driven by favorable changes in protein potential energy and configurational entropy, but it is also accompanied by an unfavorable increase in solvation free energy. The subsequent dimerization of the misfolded Aβ monomers occurs in two steps. The first step, where two widely separated monomers come into contact distance, is driven by water-mediated attraction, that is, by a

  1. 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

  2. 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

  3. 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

  4. Gas Hydrate Occurrence Inferred from Dissolved Cl− Concentrations and δ18O Values of Pore Water and Dissolved Sulfate in the Shallow Sediments of the Pockmark Field in Southwestern Xisha Uplift, Northern South China Sea

    Directory of Open Access Journals (Sweden)

    Min Luo

    2014-06-01

    Full Text Available Deep-water pockmarks are frequently accompanied by the occurrence of massive gas hydrates in shallow sediments. A decline in pore-water Cl− concentration and rise in δ18O value provide compelling evidence for the gas hydrate dissociation. Mega-pockmarks are widely scattered in the southwestern Xisha Uplift, northern South China Sea (SCS. Pore water collected from a gravity-core inside of a mega-pockmark exhibits a downward Cl− concentration decrease concomitant with an increase in δ18O value at the interval of 5.7–6.7 mbsf. Concentrations of Cl−, Na+, and K+ mainly cluster along the seawater freshening line without distinct Na+ enrichment and K+ depletion. Thus, we infer that the pore water anomalies of Cl− concentrations and δ18O values are attributed to gas hydrate dissociation instead of clay mineral dehydration. Moreover, the lower δ18O values of sulfate in the target core (C14 than those in the reference core (C9 may be associated with the equilibrium oxygen fractionation during sulfate reduction between sulfate and the relatively 18O-depleted ambient water resulting from gas hydrate formation. The gas hydrate contents are estimated to be 6%–10% and 7%–15%, respectively, according to the offset of Cl− concentrations and δ18O values from the baselines. This pockmark field in southwestern Xisha Uplift is likely to be a good prospective area for the occurrence of gas hydrate in shallow sediments.

  5. Free radicals from irradiated lyophilized DNA: influence of water of hydration

    International Nuclear Information System (INIS)

    Huettermann, J.; Roehrig, M.; Koehnlein, W.

    1992-01-01

    Lyophilized DNA equilibrated with water vapour at various relative humidities (0-95% H 2 O or D 2 O) was X-irradiated at 77 K and analysed for free radicals by electron paramagnetic resonance (EPR) spectroscopy in the temperature range 77-280 K. Analysis of spectra according to variation in humidity, microwave power and temperature generally yielded a doublet and a triplet spectrum at 77 K. The doublet partially converted into the 5-thymyl radical (TH . ). DNA containing deuterated thymine (dTDNA) revealed that the doublet of ''normal'' DNA should be composed of two similar doublets, one of which should be assigned to the thymine anion, the other possibly the cytosine anion. The triplet signal was more stable and could be related to the guanine cation or its deprotonated successor. Several other patterns were detected among them an allyl radical in highly aquated DNA (95% humidity). Other features occurred either predominantly or exclusively in DNA equilibrated above 66% relative humidity and were ascribed to an influence of the secondary structure. (author)

  6. Experimental Investigation of Effect on Hydrate Formation in Spray Reactor

    Directory of Open Access Journals (Sweden)

    Jianzhong Zhao

    2015-01-01

    Full Text Available The effects of reaction condition on hydrate formation were conducted in spray reactor. The temperature, pressure, and gas volume of reaction on hydrate formation were measured in pure water and SDS solutions at different temperature and pressure with a high-pressure experimental rig for hydrate formation. The experimental data and result reveal that additives could improve the hydrate formation rate and gas storage capacity. Temperature and pressure can restrict the hydrate formation. Lower temperature and higher pressure can promote hydrate formation, but they can increase production cost. So these factors should be considered synthetically. The investigation will promote the advance of gas storage technology in hydrates.

  7. The examination of biophysical parameters of skin (transepidermal water loss, skin hydration and pH value) in different body regions of normal cats of both sexes.

    Science.gov (United States)

    Szczepanik, Marcin P; Wilkołek, Piotr M; Adamek, Lukasz R; Pomorski, Zbigniew J H

    2011-04-01

    The purpose of this study was to evaluate transepidermal water loss (TEWL), skin hydration and skin pH in normal cats. Twenty shorthaired European cats of both sexes were examined in the study. Measurements were taken from five different sites: the lumbar region, the axillary fossa, the inguinal region, the ventral abdominal region and the left thoracic region. In each of the regions, TEWL, skin hydration and skin pH were measured. The highest TEWL value was observed in the axillary fossa (18.22g/h/m(2)) and the lowest in the lumbar region (10.53g/h/m(2)). The highest skin hydration was found in the inguinal region (18.29CU) and the lowest in the lumbar region (4.62CU). The highest skin pH was observed in the inguinal region (6.64) and the lowest in the lumbar region (6.39). Statistically significant differences in TEWL were observed between the lumbar region and the left side of the thorax region (P=0.016), the axillary fossa (P=0.0004), the ventral region (P=0.005), and the inguinal region (P=0.009). There were significant differences in skin hydration between the lumbar region and the left thorax (P=0.000003), the axillary fossa (P=0.002), the ventral abdomen (P=0.03), and the inguinal region (P=0.0003) as well as between the thorax and the ventral abdomen (P=0.005). TEWL was higher in females (15g/h/m(2)) than in males (4.57g/h/m(2)). Skin hydration was higher in females (13.89CU) than in males (12.28CU). Significant differences were not found between males and females for TEWL and skin hydration. Skin pH was higher in males (6.94) than in females (6.54), which was significant (P=0.004). Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  8. Ceramide 1 and ceramide 3 act synergistically on skin hydration and the transepidermal water loss of sodium lauryl sulfate-irritated skin.

    Science.gov (United States)

    Huang, Huey-Chun; Chang, Tsong-Min

    2008-08-01

    Stratum corneum intercellular lipids, such as ceramides, play an important role in the regulation of skin water barrier homeostasis and water-holding capacity. Aim To evaluate the potential water retention capacity of control emulsion and three oil-in-water (o/w) emulsions containing ceramide 1, ceramide 3, or both. Fifteen healthy Asian women (age, 20-30 years) with healthy skin, pretreated with sodium lauryl sulfate (SLS), applied the tested emulsions twice daily over a period of 28 days. Skin hydration and transepidermal water loss (TEWL) values were measured on the indicated days with a Corneometer(R)825 and a TEWAMETER TM210, respectively. The maximum increase in skin humidity was reached after 4 weeks, with values of 21.9 +/- 1.8% and 8.9 +/- 0.9% for emulsion C and control emulsion, respectively. The maximum decrease in TEWL was also reached after 4 weeks, with values of 36.7 +/- 4.7% and 5.1 +/- 0.8% for the same emulsions. It can be concluded that all the tested ceramide-containing emulsions improved skin barrier function when compared with untreated skin. There was some indication that ceramides 1 and 3 contained in emulsion C might exert a beneficial synergistic effect on skin biochemical properties, such as skin hydration and TEWL, and play a key role in the protection mechanism against SLS irritation.

  9. CO2 solubility in aqueous solutions containing Na+, Ca2+, Cl−, SO42− and HCO3-: The effects of electrostricted water and ion hydration thermodynamics

    International Nuclear Information System (INIS)

    Gilbert, Kimberly; Bennett, Philip C.; Wolfe, Will; Zhang, Tongwei; Romanak, Katherine D.

    2016-01-01

    Dissolution of CO 2 into deep subsurface brines for carbon sequestration is regarded as one of the few viable means of reducing the amount of CO 2 entering the atmosphere. Ions in solution partially control the amount of CO 2 that dissolves, but the mechanisms of the ion's influence are not clearly understood and thus CO 2 solubility is difficult to predict. In this study, CO 2 solubility was experimentally determined in water, NaCl, CaCl 2 , Na 2 SO 4, and NaHCO 3 solutions and a mixed brine similar to the Bravo Dome natural CO 2 reservoir; ionic strengths ranged up to 3.4 molal, temperatures to 140 °C, and CO 2 pressures to 35.5 MPa. Increasing ionic strength decreased CO 2 solubility for all solutions when the salt type remained unchanged, but ionic strength was a poor predictor of CO 2 solubility in solutions with different salts. A new equation was developed to use ion hydration number to calculate the concentration of electrostricted water molecules in solution. Dissolved CO 2 was strongly correlated (R 2  = 0.96) to electrostricted water concentration. Strong correlations were also identified between CO 2 solubility and hydration enthalpy and hydration entropy. These linear correlation equations predicted CO 2 solubility within 1% of the Bravo Dome brine and within 10% of two mixed brines from literature (a 10 wt % NaCl + KCl + CaCl 2 brine and a natural Na + , Ca 2+ , Cl − type brine with minor amounts of Mg 2+ , K + , Sr 2+ and Br − ). - Highlights: • Measured CO 2 solubility in Na + , Cl − , HCO 3 - , Ca 2+ and SO 4 2− solutions at high PCO 2 . • A new equation calculates electrostricted water (mol/kgw) from hydration number. • CO 2 solubility strongly correlates (R 2  = 0.96) to electrostricted water. • Ion electrostriction of water limits its availability for CO 2 caging and solvation. • Correlations predict CO 2 solubility of several mixed brines to within 1–9%.

  10. Hydrate prevention during formation test of gas in deep water; Prevencao de formacao de hidratos durante teste de formacao de poco de gas em lamina d'agua profunda

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Renato Cunha [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2008-07-01

    This work shows a scenery of formation test in deep water, for a well of gas, for which, there were made simulations with objective of identifying possible pairs of points (Pressure x Temperature), favorable to the hydrates formation. Besides, they were made comparisons of the values obtained in the simulation with the values registered during the formation test for the well Alfa of the field Beta. Of ownership of those information, we made an evaluation of the real needs of injection of inhibitors with intention of preventing the hydrates formation in each phase of the test. In an including way, the work has as objective recommends the volumes of hydrates inhibitors to be injected in each phase of a test of formation of well of gas in deep water, in way to assure that the operations are made without there is risk of hydrates formation. (author)

  11. Measurement of the exchange rate of waters of hydration in elastin by 2D T{sub 2}-T{sub 2} correlation nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sun Cheng; Boutis, Gregory S, E-mail: gboutis@brooklyn.cuny.edu [Brooklyn College, Department of Physics, 2900 Bedford Avenue, Brooklyn, NY 11210 (United States)

    2011-02-15

    We report on a direct measurement of the exchange rate of waters of hydration in elastin by T{sub 2}-T{sub 2} exchange spectroscopy. The exchange rates in bovine nuchal ligament elastin and aortic elastin at temperatures near, below and at the physiological temperature are reported here. Using an inverse Laplace transform (ILT) algorithm, we are able to identify four components in the relaxation times. While three of the components are in good agreement with previous measurements that used multi-exponential fitting, the ILT algorithm distinguishes a fourth component having relaxation times close to that of free water and is identified as water between fibers. With the aid of scanning electron microscopy, a model is proposed that allows for the application of a two-site exchange analysis between any two components for the determination of exchange rates between reservoirs. The results of the measurements support a model (described by Urry and Parker 2002 J. Muscle Res. Cell Motil. 23 543-59) wherein the net entropy of waters of hydration should increase with increasing temperature in the inverse temperature transition.

  12. Measurement of the exchange rate of waters of hydration in elastin by 2D T2-T2 correlation nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Sun Cheng; Boutis, Gregory S

    2011-01-01

    We report on a direct measurement of the exchange rate of waters of hydration in elastin by T 2 -T 2 exchange spectroscopy. The exchange rates in bovine nuchal ligament elastin and aortic elastin at temperatures near, below and at the physiological temperature are reported here. Using an inverse Laplace transform (ILT) algorithm, we are able to identify four components in the relaxation times. While three of the components are in good agreement with previous measurements that used multi-exponential fitting, the ILT algorithm distinguishes a fourth component having relaxation times close to that of free water and is identified as water between fibers. With the aid of scanning electron microscopy, a model is proposed that allows for the application of a two-site exchange analysis between any two components for the determination of exchange rates between reservoirs. The results of the measurements support a model (described by Urry and Parker 2002 J. Muscle Res. Cell Motil. 23 543-59) wherein the net entropy of waters of hydration should increase with increasing temperature in the inverse temperature transition.

  13. Crystal water as the mol-ecular glue for obtaining different co-crystal ratios: the case of gallic acid tris-caffeine hexa-hydrate.

    Science.gov (United States)

    Vella-Zarb, L; Baisch, U

    2018-04-01

    The crystal structure of the hexa-hydrate co-crystal of gallic acid and caffeine, C 7 H 6 O 5 ·3C 8 H 10 N 4 O 2 ·6H 2 O or GAL3CAF·6H 2 O , is a remarkable example of the importance of hydrate water acting as structural glue to facilitate the crystallization of two components of different stoichiometries and thus to compensate an imbalance of hydrogen-bond donors and acceptors. The water mol-ecules provide the additional hydrogen bonds required to form a crystalline solid. Whereas the majority of hydrogen bonds forming the inter-molecular network between gallic acid and caffeine are formed by crystal water, only one direct classical hydrogen bond between two mol-ecules is formed between the carb-oxy-lic oxygen of gallic acid and the carbonyl oxygen of caffeine with d ( D ⋯ A ) = 2.672 (2) Å. All other hydrogen bonds either involve crystal water or utilize protonated carbon atoms as donors.

  14. Measurement of the Exchange Rate of Waters of Hydration in Elastin by 2D T(2)-T(2) Correlation Nuclear Magnetic Resonance Spectroscopy.

    Science.gov (United States)

    Sun, Cheng; Boutis, Gregory S

    2011-02-28

    We report on the direct measurement of the exchange rate of waters of hydration in elastin by T(2)-T(2) exchange spectroscopy. The exchange rates in bovine nuchal ligament elastin and aortic elastin at temperatures near, below and at the physiological temperature are reported. Using an Inverse Laplace Transform (ILT) algorithm, we are able to identify four components in the relaxation times. While three of the components are in good agreement with previous measurements that used multi-exponential fitting, the ILT algorithm distinguishes a fourth component having relaxation times close to that of free water and is identified as water between fibers. With the aid of scanning electron microscopy, a model is proposed allowing for the application of a two-site exchange analysis between any two components for the determination of exchange rates between reservoirs. The results of the measurements support a model (described elsewhere [1]) wherein the net entropy of bulk waters of hydration should increase upon increasing temperature in the inverse temperature transition.

  15. 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.

  16. Free Radical Chemistry of Disinfection Byproducts 1: Kinetics of Hydrated Electron and Hydroxyl Radical Reactions with Halonitromethanes in Water

    International Nuclear Information System (INIS)

    B. J. Mincher; R. V. Fox; S. P. Mezyk; T. Helgeson; S. K. Cole; W. J. Cooper; P. R. Gardinali

    2006-01-01

    Halonitromethanes are disinfection-byproducts formed during ozonation and chlorine/chloramine treatment of waters that contain bromide ion and natural organic matter. In this study, the chemical kinetics of the free-radical-induced degradations of a series of halonitromethanes were determined. Absolute rate constants for hydroxyl radical, OH, and hydrated electron, e aq - , reaction with both chlorinated and brominated halonitromethanes were measured using the techniques of electron pulse radiolysis and transient absorption spectroscopy. The bimolecular rate constants obtained, k (M -1 s -1 ), for e aq - /OH, respectively, were the following: chloronitromethane (3.01 ± 0.40) x 10 10 /(1.94 ± 0.32) x 10 8 ; dichloronitromethane (3.21 ± 0.17) x 10 10 /(5.12 ± 0.77) x 10 8 ; bromonitromethane (3.13 ± 0.06) x 10 10 /(8.36 ± 0.57) x 107; dibromonitromethane (3.07 ± 0.40) x 10 10 /(4.75 ± 0.98) x 10 8 ; tribromonitromethane (2.29 ± 0.39) x 10 10 /(3.25 ± 0.67) x 10 8 ; bromochloronitromethane (2.93 ± 0.47) x 10 10 /(4.2 ± 1.1) x 10 8 ; bromodichloronitromethane (2.68 ± 0.13) x 10 10 /(1.02 ± 0.15) x 10 8 ; and dibromochloronitromethane (2.95 ± 0.43) x 10 10 /(1.80 ± 0.31) x 10 8 at room temperature and pH ∼7. Comparison data were also obtained for hydroxyl radical reaction with bromoform (1.50 ± 0.05) x 10 8 , bromodichloromethane (7.11 ± 0.26) x 10 7 , and chlorodibromomethane (8.31 ± 0.25) x 10 7 M -1 s -1 , respectively. These rate constants are compared to recently obtained data for trichloronitromethane and bromonitromethane, as well as to other established literature data for analogous compounds

  17. Kinetics of phycocyanobilin cleavage from C-phycocyanin by methanolysis

    DEFF Research Database (Denmark)

    Malwade, Chandrakant Ramkrishna; Roda Serrat, Maria Cinta; Christensen, Knud Villy

    2016-01-01

    Phycocyanobilin (PCB) is an important linear tetrapyrrolic molecule for food as well as pharmaceutical industry. It is obtained from blue-green algae, where it is attached covalently to phycobiliproteins (C-PC and APC) present in the light harvesting complexes. In this work, cleavage of PCB from...

  18. Late Glacial temperature and precipitation changes in the lowland Neotropics by tandem measurement of δ 18O in biogenic carbonate and gypsum hydration water

    Science.gov (United States)

    Hodell, David A.; Turchyn, Alexandra V.; Wiseman, Camilla J.; Escobar, Jaime; Curtis, Jason H.; Brenner, Mark; Gilli, Adrian; Mueller, Andreas D.; Anselmetti, Flavio; Ariztegui, Daniel; Brown, Erik T.

    2012-01-01

    We applied a new method to reconstruct paleotemperature in the tropics during the last deglaciation by measuring oxygen isotopes of co-occurring gypsum hydration water and biogenic carbonate in sediment cores from two lakes on the Yucatan Peninsula. Oxygen and hydrogen isotope values of interstitial and gypsum hydration water indicate that the crystallization water preserves the isotopic signal of the lake water, and has not undergone post-depositional isotopic exchange with sediment pore water. The estimated lake water δ18O is combined with carbonate δ18O to calculate paleotemperature. Three paired measurements of 1200-yr-old gypsum and gastropod aragonite from Lake Chichancanab, Mexico, yielded a mean temperature of 26 °C (range 23-29.5 °C), which is consistent with the mean and range of mean annual temperatures (MAT) in the region today. Paired measurements of ostracods, gastropods, and gypsum hydration water samples were measured in cores from Lake Petén Itzá, Guatemala, spanning the Late Glacial and early Holocene period (18.5-10.4 ka). The lowest recorded temperatures occurred at the start of Heinrich Stadial (HS) 1 at 18.5 ka. Inferred temperatures from benthic ostracods ranged from 16 to 20 °C during HS 1, which is 6-10 °C cooler than MAT in the region today, whereas temperatures derived from shallow-water gastropods were generally warmer (20-25 °C), reflecting epilimnetic temperatures. The derived temperatures support previous findings of greater tropical cooling on land in Central America during the Late Glacial than indicated by nearby marine records. Temperature increased in two steps during the last deglaciation. The first occurred during the Bolling-Allerod (B-A; from 14.7 to 13 ka) when temperature rose to 20-24 °C towards the end of this period. The second step occurred at 10.4 ka near the beginning of the Holocene when ostracod-inferred temperature rose to 26 °C, reflecting modern hypolimnetic temperature set during winter, whereas

  19. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    1998-01-01

    This report deals with gas phase hydration of pure cement clinker minerals at reduced relative humidities. This is an important subject in relation to modern high performance concrete which may self-desiccate during hydration. In addition the subject has relevance to storage stability where...... prehydration may occur. In the report both theoretical considerations and experimental data are presented. It is suggested that the initiation of hydration during water vapour exposure is nucleation controlled....

  20. 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.

  1. Elevated Serum Osmolality and Total Water Deficit Indicate Impaired Hydration Status in Residents of Long-Term Care Facilities Regardless of Low or High Body Mass Index.

    Science.gov (United States)

    Marra, Melissa Ventura; Simmons, Sandra F; Shotwell, Matthew S; Hudson, Abbie; Hollingsworth, Emily K; Long, Emily; Kuertz, Brittany; Silver, Heidi J

    2016-05-01

    Dehydration is typically associated with underweight and malnutrition in long-term care (LTC) settings. Evidence is lacking regarding the influence of the rising prevalence of overweight and obesity on risk factors, prevalence, and presentation of dehydration. The aim of this study was to objectively assess hydration status and the adequacy of total water intake, and determine relationships between hydration status, total water intake, and body mass index (BMI) in LTC residents. A cross-sectional analysis of baseline data was performed. Baseline data from 247 subjects recruited from eight community-based LTC facilities participating in two randomized trials comparing nutrient and cost-efficacy of between-meal snacks vs oral nutrition supplements (ONS). Hydration status was assessed by serum osmolality concentration and total water intakes were quantified by weighed food, beverage, water, and ONS intake. Simple and multiple linear regression methods were applied. Forty-nine (38.3%) subjects were dehydrated (>300 mOsm/kg) and another 39 (30.5%) had impending dehydration (295 to 300 mOsm/kg). The variance in serum osmolality was significantly accounted for by blood urea nitrogen level, mental status score, and having diabetes (R(2)=0.46; PTotal water intake averaged 1,147.2±433.1 mL/day. Thus, 96% to 100% of subjects did not meet estimated requirements, with a deficit range of 700 to 1,800 mL/day. The variance in total water intake was significantly accounted for by type of liquid beverages (thin vs thick), type of ONS, total energy intake, total activities of daily living dependence, sex, and BMI (R(2)=0.56; Ptotal water intake is prevalent in LTC residents across all BMI categories. Type of liquid beverages, type of ONS, and type of between-meal snacks are factors that could be targeted for nutrition interventions designed to prevent or reverse dehydration. Copyright © 2016 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

  2. An oil-soluble extract of Rubus idaeus cells enhances hydration and water homeostasis in skin cells.

    Science.gov (United States)

    Tito, A; Bimonte, M; Carola, A; De Lucia, A; Barbulova, A; Tortora, A; Colucci, G; Apone, F

    2015-12-01

    Raspberry plants, belonging to the species of Rubus idaeus, are known for their excellent therapeutic properties as they are particularly rich in compounds with strong antioxidant activity, which promote health and well-being of human cells. Besides their high content of phenolic compounds, Rubus plants are rich in oil-soluble compounds, which are also primary components of the hydrolipidic film barrier of the skin. As plant cell cultures represented a valuable system to produce interesting compounds and ingredients for cosmetic applications, we developed liquid suspension cultures from Rubus idaeus leaves and used them to obtain an active ingredient aimed at improving hydration and moisturization capacity in the skin. Rubus idaeus cells, grown in the laboratory under sterile and controlled conditions as liquid suspension cultures, were processed to obtain an oil-soluble (liposoluble) extract, containing phenolic compounds and a wide range of fatty acids. The extract was tested on cultured keratinocytes and fibroblasts and then on the skin in vivo, to assess its cosmetic activities. When tested on skin cell cultures, the extract induced the genes responsible for skin hydration, such as aquaporin 3, filaggrin, involucrin and hyaluronic acid synthase, and stimulated the expression and the activity of the enzyme glucocerebrosidase, involved in ceramide production. Moreover, the liposoluble extract increased the synthesis of the extracellular matrix components in cultured fibroblasts and showed a remarkable skin-hydrating capacity when tested on human skin in vivo. Thanks to these activities, the Rubus idaeus liposoluble extract has several potential applications in skin care cosmetics: it can be used as hydrating and moisturizing ingredient in face and body lotions, and as anti-ageing product in face creams specifically designed to fight wrinkle formation. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  3. 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.

  4. Free energy of hydration of niobium oxide

    International Nuclear Information System (INIS)

    Plodinec, M.J.

    1996-01-01

    Some of the glasses being formulated by SRTC researchers contain niobium oxide. In this report, the free energy of hydration of the oxide is calculated from the free energies of formation of the oxide, the hydroxide, and water. This value can be used in calculations of the free energy of hydration of glasses containing niobium

  5. 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...

  6. Development of hydrate risk quantification in oil and gas production

    Science.gov (United States)

    Chaudhari, Piyush N.

    Subsea flowlines that transport hydrocarbons from wellhead to the processing facility face issues from solid deposits such as hydrates, waxes, asphaltenes, etc. The solid deposits not only affect the production but also pose a safety concern; thus, flow assurance is significantly important in designing and operating subsea oil and gas production. In most subsea oil and gas operations, gas hydrates form at high pressure and low temperature conditions, causing the risk of plugging flowlines, with a undesirable impact on production. Over the years, the oil and gas industry has shifted their perspective from hydrate avoidance to hydrate management given several parameters such as production facility, production chemistry, economic and environmental concerns. Thus, understanding the level of hydrate risk associated with subsea flowlines is an important in developing efficient hydrate management techniques. In the past, hydrate formation models were developed for various flow-systems (e.g., oil dominated, water dominated, and gas dominated) present in the oil and gas production. The objective of this research is to extend the application of the present hydrate prediction models for assessing the hydrate risk associated with subsea flowlines that are prone to hydrate formation. It involves a novel approach for developing quantitative hydrate risk models based on the conceptual models built from the qualitative knowledge obtained from experimental studies. A comprehensive hydrate risk model, that ranks the hydrate risk associated with the subsea production system as a function of time, hydrates, and several other parameters, which account for inertial, viscous, interfacial forces acting on the flow-system, is developed for oil dominated and condensate systems. The hydrate plugging risk for water dominated systems is successfully modeled using The Colorado School of Mines Hydrate Flow Assurance Tool (CSMHyFAST). It is found that CSMHyFAST can be used as a screening tool in

  7. Physicochemical Properties of α-Form Hydrated Crystalline Phase of 3-(10-Carboxydecyl)-1,1,1,3,5,5,5-heptamethyl Trisiloxane/Higher alcohol/Polyoxyethylene (5 mol) Glyceryl monostearate/Water System.

    Science.gov (United States)

    Uyama, Makoto; Araki, Hidefumi; Fukuhara, Tadao; Watanabe, Kei

    2018-06-07

    The α-form hydrated crystalline phase (often called as an α-gel) is one of the hydrated crystalline phases which can be exhibited by surfactants and lipids. In this study, a novel system of an α-form hydrated crystal was developed, composed of 3-(10-carboxydecyl)-1,1,1,3,5,5,5-heptamethyl trisiloxane (CDTS), polyoxyethylene (5 mol) glyceryl monostearate (GMS-5), higher alcohol. This is the first report to indicate that a silicone surfactant can form an α-form hydrated crystal. The physicochemical properties of this system were characterized by small and wide angle X-ray scattering (SWAXS), differential scanning calorimetry (DSC), and diffusion-ordered NMR spectroscopy (DOSY) experiments. SWAXS and DSC measurements revealed that a plurality of crystalline phases coexist in the CDTS/higher alcohol/water ternary system. By adding GMS-5 to the ternary system, however, a wide region of a single α-form hydrated crystalline phase was obtained. The self-diffusion coefficients (D sel ) from the NMR measurements suggested that all of the CDTS, GMS-5, and higher alcohol molecules were incorporated into the same α-form hydrated crystals.

  8. Radiolysis of liquid water: an attempt to reconcile Monte-Carlo calculations with new experimental hydrated electron yield data at early times

    International Nuclear Information System (INIS)

    Muroya, Y.; Meesungnoen, J.; Jay-Gerin, J.-P.; Filali-Mouhim, A.; Goulet, T.; Katsumura, Y.; Mankhetkorn, S.

    2002-01-01

    A re-examination of our Monte-Carlo modeling of the radiolysis of liquid water by low linear-energy-transfer (LET ∼ 0.3 keV μm -1 ) radiation is undertaken herein in an attempt to reconcile the results of our simulation code with recently revised experimental hydrated electron (e aq - ) yield data at early times. The thermalization distance of subexcitation electrons, the recombination cross section of the electrons with their water parent cations prior to thermalization, and the branching ratios of the different competing mechanisms in the dissociative decay of vibrationally excited states of water molecules were taken as adjustable parameters in our simulations. Using a global-fit procedure, we have been unable to find a set of values for those parameters to simultaneously reproduce (i) the revised e aq - yield of 4.0 ± 0.2 molecules per 100 eV at 'time zero' (that is, a reduction of ∼20% over the hitherto accepted value of 4.8 molecules per 100 eV), (ii) the newly measured e aq - decay kinetic profile from 100 ps to 10 ns, and (iii) the time-dependent yields of the other radiolytic species H . , . OH, H 2 , and H 2 O 2 (up to ∼1 μs). The lowest possible limiting 'time-zero' yield of e aq - that we could in fact obtain, while ensuring an acceptable agreement between all computed and experimental yields, was ∼4.4 to 4.5 molecules per 100 eV. Under these conditions, the mean values of the electron thermalization distance and of the geminate electron-cation recombination probability, averaged over the subexcitation electron 'entry spectrum,' are found to be equal to ∼139 A and ∼18%, respectively. These values are to be compared with those obtained in our previous simulations of liquid water radiolysis, namely ∼88 A and ∼5.5%, respectively. Our average electron thermalization distance is also to be compared with the typical size (∼64-80 A) of the initial hydrated electron distributions estimated in current deterministic models of 'spur' chemistry

  9. Selected specific rates of reactions of transients from water in aqueous solution. Hydrated electron, supplemental data. [Reactions with transients from water, with inorganic solutes, and with solutes

    Energy Technology Data Exchange (ETDEWEB)

    Ross, A.B.

    1975-06-01

    A compilation of rates of reactions of hydrated electrons with other transients and with organic and inorganic solutes in aqueous solution appeared in NSRDS-NBS 43, and covered the literature up to early 1971. This supplement includes additional rates which have been published through July 1973.

  10. Amorphous boron-doped sodium titanates hydrates: Efficient and reusable adsorbents for the removal of Pb{sup 2+} from water

    Energy Technology Data Exchange (ETDEWEB)

    Di Bitonto, Luigi; Volpe, Angela; Pagano, Michele; Bagnuolo, Giuseppe; Mascolo, Giuseppe [CNR-IRSA, Via de Blasio 5, 70132 Bari (Italy); La Parola, Valeria [CNR-ISMN, Via U. La Malfa, 153, 90146 Palermo (Italy); Di Leo, Paola [CNR-IMAA, Via S. Loja, Tito Scalo (PZ) (Italy); Pastore, Carlo, E-mail: carlo.pastore@ba.irsa.cnr.it [CNR-IRSA, Via de Blasio 5, 70132 Bari (Italy)

    2017-02-15

    Highlights: • Amorphous B-doped sodium titanates hydrates were mildly synthesized. • These compounds resulted efficiently used in removing Pb{sup 2+} from natural water. • Adsorption occurs with a partial ionic exchange mechanism. • Adsorbents were easily recoverable and reusable for further new cycles. - Abstract: Amorphous titanium hydroxide and boron-doped (B-doped) sodium titanates hydrates were synthetized and used as adsorbents for the removal of Pb{sup 2+} from water. The use of sodium borohydride (NaBH{sub 4}) and titanium(IV) isopropoxide (TTIP) as precursors permits a very easy synthesis of B-doped adsorbents at 298 K. The new adsorbent materials were first chemically characterized (XRD, XPS, SEM, DRIFT and elemental analysis) and then tested in Pb{sup 2+} adsorption batch experiments, in order to define kinetics and equilibrium studies. The nature of interaction between such sorbent materials and Pb{sup 2+} was also well defined: besides a pure adsorption due to hydroxyl interaction functionalities, there is also an ionic exchange between Pb{sup 2+} and sodium ions even working at pH 4.4. Langmuir model presented the best fitting with a maximum adsorption capacity up to 385 mg/g. The effect of solution pH and common ions (i.e. Na{sup +}, Ca{sup 2+} and Mg{sup 2+}) onto Pb{sup 2+} sorption were also investigated. Finally, recovery was positively conducted using EDTA. Very efficient adsorption (>99.9%) was verified even using tap water spiked with traces of Pb{sup 2+} (50 ppb).

  11. 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

  12. 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.

  13. Is Br2 hydration hydrophobic?

    Science.gov (United States)

    Alcaraz-Torres, A; Gamboa-Suárez, A; Bernal-Uruchurtu, M I

    2017-02-28

    The spectroscopic properties of bromine in aqueous systems suggest it can behave as either hydrophilic or hydrophobic solute. In small water clusters, the halogen bond and the hydrogen-halogen interaction are responsible for its specific way of binding. In water hydrates, it is efficiently hosted by two different cages forming the crystal structure and it has been frequently assumed that there is little or no interaction between the guest and the host. Bromine in liquid solution poses a challenging question due to its non-negligible solubility and the large blue shift measured in its absorption spectra. Using a refined semi-empirical force field, PM3-PIF, we performed a Born-Oppenheimer molecular dynamics study of bromine in liquid water. Here we present a detailed study in which we retrieved the most representative hydration structures in terms of the most frequent positions around bromine and the most common water orientations. Albeit being an approximate description of the total hydration phenomenon, it captures the contribution of the leading molecular interactions in form of the recurrent structures. Our findings confirm that the spectroscopic signature is mainly caused by the closest neighbors. The dynamics of the whole first hydration shell strongly suggests that the external molecules in that structure effectively isolate the bulk from the presence of bromine. The solvation structure fluctuates from a hydrophilic to a hydrophobic-like environment along the studied trajectory.

  14. Investigation of water mobility and diffusivity in hydrating micronized low-substituted hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and hydroxypropyl cellulose matrix tablets by magnetic resonance imaging (MRI).

    Science.gov (United States)

    Kojima, Masazumi; Nakagami, Hiroaki

    2002-12-01

    The water mobility and diffusivity in the gel-layer of hydrating low-substituted hydroxypropyl cellulose (LH41) tablets with or without a drug were investigated by magnetic resonance imaging (MRI) and compared with those properties in the gel-layer of hydroxypropylmethyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) tablets. For this purpose, a localized image-analysis method was newly developed, and the spin-spin relaxation time (T(2)) and apparent self-diffusion coefficient (ADC) of water in the gel-layer were visualized in one-dimensional maps. Those maps showed that the extent of gel-layer growth in the tablets was in the order of HPC>HPMC>LH41, and there was a water mobility gradient across the gel-layers of all three tablet formulations. The T(2) and ADC in the outer parts of the gel-layers were close to those of free water. In contrast, these values in the inner parts of the gel-layer decreased progressively; suggesting that the water mobility and diffusivity around the core interface were highly restricted. Furthermore, the correlation between the T(2) of (1)H proton in the gel-layer of the tablets and the drug release rate from the tablets was observed.

  15. Investigation of water mobility and diffusivity in hydrating micronized low-substituted hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and hydroxypropyl cellulose matrix tablets by magnetic resonance imaging (MRI)

    International Nuclear Information System (INIS)

    Kojima, Masazumi; Nakagami, Hiroaki

    2002-01-01

    The water mobility and diffusivity in the gel-layer of hydrating low-substituted hydroxypropyl cellulose (LH41) tablets with or without a drug were investigated by magnetic resonance imaging (MRI) and compared with those properties in the gel-layer of hydroxypropylmethyl cellulose (HPMC) and hydroxypropyl cellulose (HPC) tablets. For this purpose, a localized image-analysis method was newly developed, and the spin-spin relaxation time (T 2 ) and apparent self-diffusion coefficient (ADC) of water in the gel-layer were visualized in one-dimensional maps. Those maps showed that the extent of gel-layer growth in the tablets was in the order of HPC>HPMC>>LH41, and there was a water mobility gradient across the gel-layers of all three tablet formulations. The T 2 and ADC in the outer parts of the gel-layers were close to those of free water. In contrast, these values in the inner parts of the gel-layer decreased progressively; suggesting that the water mobility and diffusivity around the core interface were highly restricted. Furthermore, the correlation between the T 2 of 1 H proton in the gel-layer of the tablets and the drug release rate from the tablets was observed. (author)

  16. 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

  17. Simulation and Characterization of Methane Hydrate Formation

    Science.gov (United States)

    Dhakal, S.; Gupta, I.

    2017-12-01

    The ever rising global energy demand dictates human endeavor to explore and exploit new and innovative energy sources. As conventional oil and gas reserves deplete, we are constantly looking for newer sources for sustainable energy. Gas hydrates have long been discussed as the next big energy resource to the earth. Its global occurrence and vast quantity of natural gas stored is one of the main reasons for such interest in its study and exploration. Gas hydrates are solid crystalline substances with trapped molecules of gas inside cage-like crystals of water molecules. Gases such as methane, ethane, propane and carbon dioxide can form hydrates but in natural state, methane hydrates are the most common. Subsurface geological conditions with high pressure and low temperature favor the formation and stability of gas hydrates. While the occurrence and potential of gas hydrates as energy source has long been studied, there are still gaps in knowledge, especially in the quantitative research of gas hydrate formation and reservoir characterization. This study is focused on exploring and understanding the geological setting in which gas hydrates are formed and the subsequent changes in rock characteristics as they are deposited. It involves the numerical simulation of methane gas flow through fault to form hydrates. The models are representative of the subsurface geologic setting of Gulf of Mexico with a fault through layers of shale and sandstone. Hydrate formation simulated is of thermogenic origin. The simulations are conducted using TOUGH+HYDRATE, a numerical code developed at the Lawrence Berkley National Laboratory for modeling multiphase flow through porous medium. Simulation results predict that as the gas hydrates form in the pores of the model, the porosity, permeability and other rock properties are altered. Preliminary simulation results have shown that hydrates begin to form in the fault zone and gradually in the sandstone layers. The increase in hydrate

  18. 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 ...

  19. Morphology studies on gas hydrates interacting with silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Beltran, J.; Servio, P. [McGill Univ., Montreal, PQ (Canada). Dept. of Chemical Engineering

    2008-07-01

    Clathrate hydrates or gas hydrates are non-stoichiometric, crystalline compounds that form when small molecules come in contact with water at certain temperatures and pressures. Natural gas hydrates are found in the ocean bottom and in permafrost regions. It is thought that the amount of energy stored in natural hydrates is at least twice that of all other fossil fuels combined. In addition, trapping carbon dioxide as a hydrate in the bottom of the ocean has been suggested as an alternative means of reducing atmospheric carbon dioxide levels. Naturally occurring clathrates are found in close interaction with fine grained particles of very small mean pore diameters. Even though an increasing amount of hydrate equilibrium data for small diameter porous media has become available, the morphological behavior of hydrates subject to such conditions is yet to be explored. This paper presented a study that visually examined hydrate formation and decomposition of gas hydrates while interacting with fine grains of silica gel. The study showed still frames from high-resolution video recordings for hydrate formation and decomposition. The paper discussed the experiment including the apparatus as well as the results of hydrate formation and hydrate dissociation. This study enabled for the first time to observe clathrate morphology while hydrates interacted closely with fine grain particles with small mean pore diameters. 9 refs., 8 figs.

  20. The temperature hydration kinetics

    Directory of Open Access Journals (Sweden)

    Mircea Oroian

    2017-07-01

    Full Text Available The aim of this study is to evaluate the hydration kinetics of lentil seeds (Lens culinaris in water at different temperatures (25, 32.5, 40, 55, 70 and 80 °C for assessing the adequacy of models for describing the absorption phenomena during soaking. The diffusion coefficient values were calculated using Fick’s model for spherical and hemispherical geometries and the values were in the range of 10−6 m2/s. The experimental data were fitted to Peleg, Sigmoidal, Weibull and Exponential models. The models adequacy was determined using regression coefficients (R2, root mean square error (RMSE and reduced chi-square (χ2. The Peleg model is the suitable one for predicting the experimental data. Temperature had a positive and significant effect on the water absorption capacities and absorption was an endothermic process.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Raman and infrared spectroscopic studies of the structure of water (H2O, HOD, D2O) in stoichiometric crystalline hydrates and in electrolyte solutions

    International Nuclear Information System (INIS)

    Buanam-Om, C.

    1981-01-01

    The chapter of reviews presents in particular the Badger-Bauer-rule, distance and angle dependence of O-H...Y hydrogen bond and the structure of aqueous electrolyte solutions. A chapter of vibrational spectroscopic investigations of crystalline hydrates - metal perchlorate hydrates follows. Two further chapters just so investigate metal halide hydrates and some sulfate hydrates and related systems. The following chapter describes near infrared spectroscopic investigations of HOD(D 2 O) and its electrolyte solutions. The concluding chapter contains thermodynamic consequences and some properties of electrolyte solutions from vibrational spectroscopic investigations. (SPI) [de

  6. 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.

  7. Production of Hydrated Metal Ions by Fast Ion or Atom Beam Sputtering. Collision-Induced Dissociation and Successive Hydration Energies of Gaseous Cu+ with 1-4 Water Molecules

    NARCIS (Netherlands)

    Magnera, Thomas F.; David, Donald E.; Stulik, Dusan; Orth, Robert G.; Jonkman, Harry T.; Michl, Josef

    1989-01-01

    Low-temperature sputtering of frozen aqueous solutions of metal salts, of hydrated crystalline transition-metal salts, of frosted metal surfaces, and of frosted metal salts with kiloelectronvolt energy rare gas atoms or ions produces copious amounts of cluster ions, among which M+(H2O)n and/or

  8. 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

  9. Hydration states of AFm cement phases

    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; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2015-07-15

    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  10. 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)

  11. Combining Multicomponent Seismic Attributes, New Rock Physics Models, and In Situ Data to Estimate Gas-Hydrate Concentrations in Deep-Water, Near-Seafloor Strata of the Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Bureau of Economic Geology

    2009-04-30

    The Bureau of Economic Geology was contracted to develop technologies that demonstrate the value of multicomponent seismic technology for evaluating deep-water hydrates across the Green Canyon area of the Gulf of Mexico. This report describes the methodologies that were developed to create compressional (P-P) and converted-shear (P-SV) images of near-seafloor geology from four-component ocean-bottom-cable (4C OBC) seismic data and the procedures used to integrate P-P and P-SV seismic attributes with borehole calibration data to estimate hydrate concentration across two study areas spanning 16 and 25 lease blocks (or 144 and 225 square miles), respectively. Approximately 200 km of two-dimensional 4C OBC profiles were processed and analyzed over the course of the 3-year project. The strategies we developed to image near-seafloor geology with 4C OBC data are unique, and the paper describing our methodology was peer-recognized with a Best Paper Award by the Society of Exploration Geophysicists in the first year of the project (2006). Among the valuable research findings demonstrated in this report, the demonstrated ability to image deep-water near-seafloor geology with sub-meter resolution using a standard-frequency (10-200 Hz) air gun array on the sea surface and 4C sensors on the seafloor has been the accomplishment that has received the most accolades from professional peers. Our study found that hydrate is pervasive across the two study areas that were analyzed but exists at low concentrations. Although our joint inversion technique showed that in some limited areas, and in some geologic units across those small areas, hydrates occupied up to 40-percent of the sediment pore space, we found that when hydrate was present, hydrate concentration tended to occupy only 10-percent to 20-percent of the pore volume. We also found that hydrate concentration tended to be greater near the base of the hydrate stability zone than it was within the central part of the stability

  12. 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

  13. Raman studies of methane-ethane hydrate metastability.

    Science.gov (United States)

    Ohno, Hiroshi; Strobel, Timothy A; Dec, Steven F; Sloan, E Dendy; Koh, Carolyn A

    2009-03-05

    The interconversion of methane-ethane hydrate from metastable to stable structures was studied using Raman spectroscopy. sI and sII hydrates were synthesized from methane-ethane gas mixtures of 65% or 93% methane in ethane and water, both with and without the kinetic hydrate inhibitor, poly(N-vinylcaprolactam). The observed faster structural conversion rate in the higher methane concentration atmosphere can be explained in terms of the differences in driving force (difference in chemical potential of water in sI and sII hydrates) and kinetics (mass transfer of gas and water rearrangement). The kinetic hydrate inhibitor increased the conversion rate at 65% methane in ethane (sI is thermodynamically stable) but retards the rate at 93% methane in ethane (sII is thermodynamically stable), implying there is a complex interaction between the polymer, water, and hydrate guests at crystal surfaces.

  14. Kinetic of formation for single carbon dioxide and mixed carbon dioxide and tetrahydrofuran hydrates in water and sodium chloride aqueous solution

    NARCIS (Netherlands)

    Sabil, K.M.; Duarte, A.R.C.; Zevenbergen, J.F.; Ahmad, M.M.; Yusup, S.; Omar, A.A.; Peters, C.J.

    2010-01-01

    A laboratory-scale reactor system is built and operated to measure the kinetic of formation for single and mixed carbon dioxide-tetrahydrofuran hydrates. The T-cycle method, which is used to collect the kinetic data, is briefly discussed. For single carbon dioxide hydrate, the induction time

  15. Relationship between interlayer hydration and photocatalytic water splitting of A'1-xNaxCa2Ta3O10.nH2O (A'=K and Li)

    International Nuclear Information System (INIS)

    Mitsuyama, Tomohiro; Tsutsumi, Akiko; Sato, Sakiko; Ikeue, Keita; Machida, Masato

    2008-01-01

    Partial replacement of alkaline metals in anhydrous KCa 2 Ta 3 O 10 and LiCa 2 Ta 3 O 10 was studied to control interlayer hydration and photocatalytic activity for water splitting under UV irradiation. A' 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O (A'=K and Li) samples were synthesized by ion exchange of CsCa 2 Ta 3 O 10 in mixed molten nitrates at 400 deg. C. In K 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O, two phases with the orthorhombic (C222) and tetragonal (I4/mmm) structures were formed at x≤0.7 and x≥0.5, respectively. Upon replacement by Na + having a larger enthalpy of hydration (ΔH h 0 ), the interlayer hydration occurred at x≥0.3 and the hydration number (n) was increased monotonically with an increase of x. Li 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O showed a similar hydration behavior, but the phase was changed from I4/mmm (x 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O exhibited the activity increasing in consistent with n, whereas Li 1-x Na x Ca 2 Ta 3 O 10 .nH 2 O exhibited the activity maximum at x=0.77, where the rates of H 2 /O 2 evolution were nearly doubled compared with those for end-member compositions (x=0 and 1). - Graphical abstract: The partial substitution of Na in the interlayer of anhydrous-layered perovskite has been found as useful structural modification toward highly active hydrated photocatalysts

  16. 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.

  17. Characteristics of Methane Hydrate Formation in Artificial and Natural Media

    OpenAIRE

    Peng Zhang; Qingbai Wu; Yuzhong Yang

    2013-01-01

    The formation of methane hydrate in two significantly different media was investigated, using silica gel as an artificial medium and loess as a natural medium. The methane hydrate formation was observed through the depletion of water in the matrix, measured via the matrix potential and the relationship between the matrix potential and the water content was determined using established equations. The velocity of methane hydrate nucleation slowed over the course of the reaction, as it relied on...

  18. Tapping methane hydrates for unconventional natural gas

    Science.gov (United States)

    Ruppel, Carolyn

    2007-01-01

    Methane hydrate is an icelike form of concentrated methane and water found in the sediments of permafrost regions and marine continental margins at depths far shallower than conventional oil and gas. Despite their relative accessibility and widespread occurrence, methane hydrates have never been tapped to meet increasing global energy demands. With rising natural gas prices, production from these unconventional gas deposits is becoming economically viable, particularly in permafrost areas already being exploited for conventional oil and gas. This article provides an overview of gas hydrate occurrence, resource assessment, exploration, production technologies, renewability, and future challenges.

  19. Carbon dioxide hydrate formation in a fixed-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fan, S.; Lang, X. [South China Univ. of Technology, Guangzhou (China). Key Laboratory of Enhanced Heat Transfer and Energy Conservation; Wang, Y.; Liang, D. [Chinese Academy of Sciences, Guangzhou (China). Guangzhou Inst. of Energy Conversion and Guangzhou Center of Natural Gas Hydrate; Sun, X.; Jurcik, B. [Air Liquide Laboratories, Tsukuba (Japan)

    2008-07-01

    Gas hydrates are thermodynamically stable at high pressures and near the freezing temperature of pure water. Methane hydrates occur naturally in sediments in the deep oceans and permafrost regions and constitute an extensive hydrocarbon reservoir. Carbon dioxide (CO{sub 2}) hydrates are of interest as a medium for marine sequestration of anthropogenic carbon dioxide. Sequestering CO{sub 2} as hydrate has potential advantages over most methods proposed for marine CO{sub 2} sequestration. Because this technique requires a shallower depth of injection when compared with other ocean sequestration methods, the costs of CO{sub 2} hydrate sequestration may be lower. Many studies have successfully used different continuous reactor designs to produce CO{sub 2} hydrates in both laboratory and field settings. This paper discussed a study that involved the design and construction of a fixed-bed reactor for simulation of hydrate formation system. Water, river sands and carbon dioxide were used to simulate the seep kind of hydrate formation. Carbon dioxide gas was distributed as small bubbles to enter from the bottom of the fixed-bed reactor. The paper discussed the experimental data and presented a diagram of the gas hydrate reactor system. The morphology as well as the reaction characters of CO{sub 2} hydrate was presented in detail. The results were discussed in terms of experimental phenomena and hydrate formation rate. A mathematical model was proposed for describing the process. 17 refs., 7 figs.

  20. Hydration structure and dynamics of a hydroxide ion in water clusters of varying size and temperature: Quantum chemical and ab initio molecular dynamics studies

    International Nuclear Information System (INIS)

    Bankura, Arindam; Chandra, Amalendu

    2012-01-01

    Highlights: ► A theoretical study of hydroxide ion-water clusters is carried for varying cluster size and temperature. ► The structures of OH − (H 2 O) n are found out through quantum chemical calculations for n = 4, 8, 16 and 20. ► The finite temperature behavior of the clusters is studied through ab initio dynamical simulations. ► The spectral features of OH modes (deuterated) and their dependence on hydrogen bonding states of water are discussed. ► The mechanism and kinetics of proton transfer processes in these anionic clusters are also investigated. - Abstract: We have investigated the hydration structure and dynamics of OH − (H 2 O) n clusters (n = 4, 8, 16 and 20) by means of quantum chemical and ab initio molecular dynamics calculations. Quantum chemical calculations reveal that the solvation structure of the hydroxide ion transforms from three and four-coordinated surface states to five-coordinated interior state with increase in cluster size. Several other isomeric structures with energies not very different from the most stable isomer are also found. Ab initio simulations show that the most probable configurations at higher temperatures need not be the lowest energy isomeric structure. The rates of proton transfer in these clusters are found to be slower than that in bulk water. The vibrational spectral calculations reveal distinct features for free OH (deuterated) stretch modes of water in different hydrogen bonding states. Effects of temperature on the structural and dynamical properties are also investigated for the largest cluster considered here.

  1. LABORATORY STRATEGIES FOR HYDRATE FORMATION IN FINE-GRAINED SEDIMENTS

    KAUST Repository

    Lei, L.; Santamarina, Carlos

    2018-01-01

    Fine‐grained sediments limit hydrate nucleation, shift the phase boundary and hinder gas supply. Laboratory experiments in this study explore different strategies to overcome these challenges, including the use of a more soluble guest molecule rather than methane, grain‐scale gas‐storage within porous diatoms, ice‐to‐hydrate transformation to grow lenses at predefined locations, forced gas injection into water saturated sediments, and long‐term guest molecule transport. Tomographic images, thermal and pressure data provide rich information on hydrate formation and morphology. Results show that hydrate formation is inherently displacive in fine‐grained sediments; lenses are thicker and closer to each other in compressible, high specific surface area sediments subjected to low effective stress. Temperature and pressure trajectories follow a shifted phase boundary that is consistent with capillary effects. Exo‐pore growth results in freshly formed hydrate with a striped and porous structure; this open structure becomes an effective pathway for gas transport to the growing hydrate front. Ice‐to‐hydrate transformation goes through a liquid stage at pre‐melt temperatures; then, capillarity and cryogenic suction compete, and some water becomes imbibed into the sediment faster than hydrate reformation. The geometry of hydrate lenses and the internal hydrate structure continue evolving long after the exothermal response to hydrate formation has completely decayed. Multiple time‐dependent processes occur during hydrate formation, including gas, water and heat transport, sediment compressibility, reaction rate and the stochastic nucleation process. Hydrate formation strategies conceived for this study highlight the inherent difficulties in emulating hydrate formation in fine‐grained sediments within the relatively short time‐scale available for laboratory experiments.

  2. LABORATORY STRATEGIES FOR HYDRATE FORMATION IN FINE-GRAINED SEDIMENTS

    KAUST Repository

    Lei, L.

    2018-04-02

    Fine‐grained sediments limit hydrate nucleation, shift the phase boundary and hinder gas supply. Laboratory experiments in this study explore different strategies to overcome these challenges, including the use of a more soluble guest molecule rather than methane, grain‐scale gas‐storage within porous diatoms, ice‐to‐hydrate transformation to grow lenses at predefined locations, forced gas injection into water saturated sediments, and long‐term guest molecule transport. Tomographic images, thermal and pressure data provide rich information on hydrate formation and morphology. Results show that hydrate formation is inherently displacive in fine‐grained sediments; lenses are thicker and closer to each other in compressible, high specific surface area sediments subjected to low effective stress. Temperature and pressure trajectories follow a shifted phase boundary that is consistent with capillary effects. Exo‐pore growth results in freshly formed hydrate with a striped and porous structure; this open structure becomes an effective pathway for gas transport to the growing hydrate front. Ice‐to‐hydrate transformation goes through a liquid stage at pre‐melt temperatures; then, capillarity and cryogenic suction compete, and some water becomes imbibed into the sediment faster than hydrate reformation. The geometry of hydrate lenses and the internal hydrate structure continue evolving long after the exothermal response to hydrate formation has completely decayed. Multiple time‐dependent processes occur during hydrate formation, including gas, water and heat transport, sediment compressibility, reaction rate and the stochastic nucleation process. Hydrate formation strategies conceived for this study highlight the inherent difficulties in emulating hydrate formation in fine‐grained sediments within the relatively short time‐scale available for laboratory experiments.

  3. Thermal conductivity measurements in unsaturated hydrate-bearing sediments

    Science.gov (United States)

    Dai, Sheng; Cha, Jong-Ho; Rosenbaum, Eilis J.; Zhang, Wu; Seol, Yongkoo

    2015-08-01

    Current database on the thermal properties of hydrate-bearing sediments remains limited and has not been able to capture their consequential changes during gas production where vigorous phase changes occur in this unsaturated system. This study uses the transient plane source (TPS) technique to measure the thermal conductivity of methane hydrate-bearing sediments with various hydrate/water/gas saturations. We propose a simplified method to obtain thermal properties from single-sided TPS signatures. Results reveal that both volume fraction and distribution of the pore constituents govern the thermal conductivity of unsaturated specimens. Thermal conductivity hysteresis is observed due to water redistribution and fabric change caused by hydrate formation and dissociation. Measured thermal conductivity increases evidently when hydrate saturation Sh > 30-40%, shifting upward from the geometric mean model prediction to a Pythagorean mixing model. These observations envisage a significant drop in sediment thermal conductivity when residual hydrate/water saturation falls below ~40%, hindering further gas production.

  4. Hydration dynamics of hyaluronan and dextran.

    Science.gov (United States)

    Hunger, Johannes; Bernecker, Anja; Bakker, Huib J; Bonn, Mischa; Richter, Ralf P

    2012-07-03

    Hyaluronan is a polysaccharide, which is ubiquitous in vertebrates and has been reported to be strongly hydrated in a biological environment. We study the hydration of hyaluronan in solution using the rotational dynamics of water as a probe. We measure these dynamics with polarization-resolved femtosecond-infrared and terahertz time-domain spectroscopies. Both experiments reveal that a subensemble of water molecules is slowed down in aqueous solutions of hyaluronan amounting to ∼15 water molecules per disaccharide unit. This quantity is consistent with what would be expected for the first hydration shell. Comparison of these results to the water dynamics in aqueous dextran solution, a structurally similar polysaccharide, yields remarkably similar results. This suggests that the observed interaction with water is a common feature for hydrophilic polysaccharides and is not specific to hyaluronan. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  5. 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.

  6. 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.

  7. 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.

  8. FY1995 molecular control technology for mining of methane-gas-hydrate; 1995 nendo methane hydrate no bunshi seigyo mining

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The objectives of the investigation are as follows: 1) developing a method to control formation/dissociation of methane-gas-hydrate, 2) developing a technology to displace methane gas by CO{sub 2} in methane-gas-hydrate deposit, 3) developing a technology to produce methane gas from the deposit efficiently. The final purpose of the project is to create new mining industry that solves both the problems of energy and global environment. 1) Clustering of water molecules is found to play the key role in the methane gas hydrate formation. 2) Equilibrium properties and kinetics of gas hydrates formation and dissociation in bulk-scale gas-hydrate are clarified in the practical environmental conditions. 3) Particle size of hydrate deposit influences the formation and dissociation of bulk-scale gas-hydrate crystal. 4) Mass transfer between gas and liquid phase in turbulent bubbly flow is a function of bubble diameter. The mass transfer depends on interfacial dynamics. (NEDO)

  9. International guidelines for the in vivo assessment of skin properties in non-clinical settings: Part 2. transepidermal water loss and skin hydration

    Science.gov (United States)

    du Plessis, Johan; Stefaniak, Aleksandr; Eloff, Fritz; John, Swen; Agner, Tove; Chou, Tzu-Chieh; Nixon, Rosemary; Steiner, Markus; Franken, Anja; Kudla, Irena; Holness, Linn

    2015-01-01

    Background There is an emerging perspective that it is not sufficient to just assess skin exposure to physical and chemical stressors in workplaces, but that it is also important to assess the condition, i.e. skin barrier function of the exposed skin at the time of exposure. The workplace environment, representing a non-clinical environment, can be highly variable and difficult to control, thereby presenting unique measurement challenges not typically encountered in clinical settings. Methods An expert working group convened a workshop as part of the 5th International Conference on Occupational and Environmental Exposure of Skin to Chemicals (OEESC) to develop basic guidelines and best practices (based on existing clinical guidelines, published data, and own experiences) for the in vivo measurement of transepidermal water loss (TEWL) and skin hydration in non-clinical settings with specific reference to the workplace as a worst-case scenario. Results Key elements of these guidelines are: (i) to minimize or recognize, to the extent feasible, the influences of relevant endogenous-, exogenous-, environmental- and measurement/instrumentation-related factors; (ii) to measure TEWL with a closed-chamber type instrument; (iii) report results as a difference or percent change (rather than absolute values); and (iv) accurately report any notable deviations from this guidelines. Conclusion It is anticipated that these guidelines will promote consistent data reporting, which will facilitate inter-comparison of study results. PMID:23331328

  10. Modeling dissociation behaviour of methane hydrate in porous soil media

    Energy Technology Data Exchange (ETDEWEB)

    Jayasinghe, A.G.; Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

    2008-07-01

    Gas hydrates, or clathrates, exist in the form of crystalline solid structures of hydrogen bonded water molecules where the lattice cages are occupied by guest gas molecules. Methane gas hydrates are the most common. As such, hydrate bearing sediments are considered to be a potential future energy resource. Gas hydrates also function as a source or sink for atmospheric methane, which may influence global warming. The authors emphasized that an understanding of the behaviour of soils containing gas hydrates is necessary in order to develop ways of recovering the vast gas resources that exist in the form of hydrates, particularly since hydrates are also suspected to be a potential factor in the initiation and propagation of submarine slope failures. Gas hydrate dissociation occurs when water and gas are released, resulting in an increase in pore fluid pressure, thereby causing significant reductions in effective stress leading to sediment failure. Dissociation may occur as a result of pressure reductions or increases in temperature. This study focused on the strength and deformation behaviour of hydrate bearing soils associated with temperature induced dissociation. Modeling the dissociation behavior of hydrates in porous soil media involves an understanding of the geomechanics of hydrate dissociation. This paper addressed the issue of coupling the hydrate dissociation problem with the soil deformation problem. A mathematical framework was constructed in which the thermally stimulated hydrate dissociation process in porous soil media under undrained conditions was considered with conduction heat transfer. It was concluded that a knowledge of geomechanical response of hydrate bearing sediments will enable better estimates of benefits and risks associated with the recovery process, thereby ensuring safe and economical exploration. 20 refs., 1 fig., 1 appendix.

  11. Simultaneous analysis of 17O/16O, 18O/16O and 2H/1H of gypsum hydration water by cavity ring‐down laser spectroscopy

    Science.gov (United States)

    Mather, Ian; Rolfe, James; Evans, Nicholas P.; Herwartz, Daniel; Staubwasser, Michael; Hodell, David A.

    2015-01-01

    Rationale The recent development of cavity ring‐down laser spectroscopy (CRDS) instruments capable of measuring 17O‐excess in water has created new opportunities for studying the hydrologic cycle. Here we apply this new method to studying the triple oxygen (17O/16O, 18O/16O) and hydrogen (2H/1H) isotope ratios of gypsum hydration water (GHW), which can provide information about the conditions under which the mineral formed and subsequent post‐depositional interaction with other fluids. Methods We developed a semi‐automated procedure for extracting GHW by slowly heating the sample to 400°C in vacuo and cryogenically trapping the evolved water. The isotopic composition (δ17O, δ18O and δ2H values) of the GHW is subsequently measured by CRDS. The extraction apparatus allows the dehydration of five samples and one standard simultaneously, thereby increasing the long‐term precision and sample throughput compared with previous methods. The apparatus is also useful for distilling brines prior to isotopic analysis. A direct comparison is made between results of 17O‐excess in GHW obtained by CRDS and fluorination followed by isotope ratio mass spectrometry (IRMS) of O2. Results The long‐term analytical precision of our method of extraction and isotopic analysis of GHW by CRDS is ±0.07‰ for δ17O values, ±0.13‰ for δ18O values and ±0.49‰ for δ2H values (all ±1SD), and ±1.1‰ and ±8 per meg for the deuterium‐excess and 17O‐excess, respectively. Accurate measurement of the 17O‐excess values of GHW, of both synthetic and natural samples, requires the use of a micro‐combustion module (MCM). This accessory removes contaminants (VOCs, H2S, etc.) from the water vapour stream that interfere with the wavelengths used for spectroscopic measurement of water isotopologues. CRDS/MCM and IRMS methods yield similar isotopic results for the analysis of both synthetic and natural gypsum samples within analytical error of the two methods. Conclusions We

  12. Reactivity of Hydrated Electron in Finite Size System: Sodium Pickup on Mixed N2O–Water Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Šmídová, Daniela; Lengyel, Jozef; Pysanenko, Andriy; Med, J.; Slavíček, P.; Fárník, Michal

    2015-01-01

    Roč. 6, č. 15 (2015), s. 2865-2869 ISSN 1948-7185 R&D Projects: GA ČR GA14-08937S Institutional support: RVO:61388955 Keywords : solvated electron * water clusters * fragmentation-free mass spectrometry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 8.539, year: 2015

  13. The Role of the Primitive Relaxation in the Dynamics of Aqueous Mixtures, Nano-confined Water and Hydrated Proteins

    Science.gov (United States)

    2010-01-01

    and polysaccharides ) and some hydrophilic macromolecular systems, including biopolymers (from polypeptides to several proteins) [r008, r009, r010...investigated and here presented are the monosaccharide 2-Deoxy-D- ribose, mixed with 32% wt. fraction of water, and the heptamer of polypropylene glycol, with

  14. Effects of various vehicles on skin hydration in vivo.

    Science.gov (United States)

    Wiedersberg, S; Leopold, C S; Guy, R H

    2009-01-01

    The stratum corneum, the outermost layer of the skin, regulates the passive loss of water to the environment. Furthermore, it is well accepted that drug penetration is influenced by skin hydration, which may be manipulated by the application of moisturizing or oleaginous vehicles. Measurements of transepidermal water loss (TEWL), and of skin hydration using a corneometer, were used to assess the effect of different vehicles on stratum corneum barrier function in vivo in human volunteers. A microemulsion significantly increased skin hydration relative to a reference vehicle based on medium chain triglycerides; in contrast, Transcutol(R) lowered skin hydration. TEWL measurements confirmed these observations. Copyright 2009 S. Karger AG, Basel.

  15. 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.

  16. Tracking all-vapor instant gas-hydrate formation and guest molecule populations: A possible probe for molecules trapped in water nanodroplets

    Czech Academy of Sciences Publication Activity Database

    Uras-Aytemiz, N.; Cwiklik, Lukasz; Devlin, J. P.

    2012-01-01

    Roč. 137, č. 20 (2012), s. 204501 ISSN 0021-9606 Institutional support: RVO:61388955 Keywords : Fourier transform infrared emission spectra * clathrate hydrate * simulations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.164, year: 2012

  17. 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...

  18. 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.

  19. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-07-01

    Full Text Available Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2.

    Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia. However most of the hydrates are located at depths in soils and ocean sediments where anthropogenic warming and any possible methane release will take place over time scales of millennia. Individual catastrophic releases like landslides and pockmark explosions are too small to reach a sizable fraction of the hydrates. The carbon isotopic excursion at the end of the Paleocene has been interpreted as the release of thousands of Gton C, possibly from hydrates, but the time scale of the release appears to have been thousands of years, chronic rather than catastrophic.

    The potential climate impact in the coming century from hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat, significant but not catastrophic. On geologic timescales, it is conceivable that hydrates could release as much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  20. Hydration of urea and alkylated urea derivatives

    Science.gov (United States)

    Kaatze, Udo

    2018-01-01

    Compressibility data and broadband dielectric spectra of aqueous solutions of urea and some of its alkylated derivatives have been evaluated to yield their numbers Nh of hydration water molecules per molecule of solute. Nh values in a broad range of solute concentrations are discussed and are compared to hydration numbers of other relevant molecules and organic ions. Consistent with previous results, it is found that urea differs from other solutes in its unusually small hydration number, corresponding to just one third of the estimated number of nearest neighbor molecules. This remarkable hydration behavior is explained by the large density φH of hydrogen bonding abilities offered by the urea molecule. In terms of currently discussed models of reorientational motions and allied dynamics in water and related associating liquids, the large density φH causes a relaxation time close to that of undisturbed water with most parts of water encircling the solute. Therefore only a small part of disturbed ("hydration") water is left around each urea molecule. Adding alkyl groups to the basic molecule leads to Nh values which, within the series of n-alkylurea derivatives, progressively increase with the number of methyl groups per solute. With n-butylurea, Nh from dielectric spectra, in conformity with many other organic solutes, slightly exceeds the number of nearest neighbors. Compared to such Nh values, hydration numbers from compressibility data are substantially smaller, disclosing incorrect assumptions in the formula commonly used to interpret the experimental compressibilities. Similar to other series of organic solutes, effects of isomerization have been found with alkylated urea derivatives, indicating that factors other than the predominating density φH of hydrogen bond abilities contribute also to the hydration properties.

  1. Constraining the origin of the Messinian gypsum deposits using coupled measurement of δ^{18}O$/δD in gypsum hydration water and salinity of fluid inclusions

    Science.gov (United States)

    Evans, Nicholas P.; Gázquez, Fernando; McKenzie, Judith A.; Chapman, Hazel J.; Hodell, David A.

    2016-04-01

    We used oxygen and hydrogen isotopes of gypsum hydration water (GHW) coupled with salinity deduced from ice melting temperatures of primary fluid inclusions in the same samples (in tandem with 87Sr/86Sr, δ34S and other isotopic measurements) to determine the composition of the mother fluids that formed the gypsum deposits of the Messinian Salinity Crisis from shallow and intermediate-depth basins. Using this method, we constrain the origin of the Messinian Primary Lower Gypsum (PLG) of the Sorbas basin (Betic foreland) and both the Upper Gypsum (UG) and the Lower Gypsum of the Sicilian basin. We then compare these results to measurements made on UG recovered from the deep Ionian and Balearic basins drilled during DSDP Leg 42A. The evolution of GHW δ18O/δD vs. salinity is controlled by mixing processes between fresh and seawater, coupled with the degree of evaporation. Evaporation and subsequent precipitation of gypsum from fluids dominated by freshwater will result in a depressed 87Sr/86Sr values and different trajectory in δ18O/δD vs. salinity space compared to fluids dominated by seawater. The slopes of these regression equations help to define the end-members from which the fluid originated. For example, salinity estimates from PLG cycle 6 in the Sorbas basin range from 18 to 51ppt, and after correction for fractionation factors, estimated δ18O and δD values of the mother water are low (-2.6 meteoric water during gypsum deposition, while 87Sr/86Sr (0.708942 fall below those expected from the evaporation of seawater alone, the slope of the regression equation is similar to that of seawater evaporation. This implies that there is a change up-section from a dominantly marine environment in cycle 2 to a greater influence of meteoric water in cycle 6. The UG from the Sicilian basin display greater δ18O/δD values (2.9 meteoric water that subsequently underwent intense evaporation. This observation concurs with the low values of 87Sr/86Sr from the same UG

  2. Effect of Gemini-type surfactant on methane hydrate formation

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, K.E.; Park, J.M.; Kim, C.U.; Chae, H.J.; Jeong, S.Y. [Korea Research Inst. of Chemical Technology, Jang-Dong, Yuseong-Gu, Daejeon (Korea, Republic of)

    2008-07-01

    Natural gas hydrates are formed from water and natural gas molecules at particular temperatures and pressures that become ice-like inclusion compounds. Gas hydrates offer several benefits such as energy resource potential and high storage capacity of natural gas in the form of hydrates. However, the application of natural gas hydrates has been deterred by its low formation rate and low conversion ratio of water into hydrate resulting in low actual storage capacity. This paper presented an experimental study to determine the effect of adding a novel Gemini-type surfactant on methane hydrate formation. The experimental study was described with reference to the properties of prepared diols and properties of prepared disulfonates. Gemini surfactant is the family of surfactant molecules possessing more than one hydrophobic tail and hydrophilic head group. They generally have better surface-active properties than conventional surfactants of equal chain length. The paper presented the results of the study in terms of the reactions of diols with propane sultone; storage capacity of hydrate formed with and without surfactant; and methane hydrate formation with and without disulfonate. It was concluded that the methane hydrate formation was accelerated by the addition of novel anionic Gemini-type surfactants and that hydrate formation was influenced by the surfactant concentration and alkyl chain length. For a given concentration, the surfactant with the highest chain length demonstrated the highest formation rate and storage capacity. 5 refs., 3 tabs., 4 figs.

  3. 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

  4. NMR Studies of Protein Hydration and Protein-Ligand Interactions

    Science.gov (United States)

    Chong, Yuan

    Water on the surface of a protein is called hydration water. Hydration water is known to play a crucial role in a variety of biological processes including protein folding, enzymatic activation, and drug binding. Although the significance of hydration water has been recognized, the underlying mechanism remains far from being understood. This dissertation employs a unique in-situ nuclear magnetic resonance (NMR) technique to study the mechanism of protein hydration and the role of hydration in alcohol-protein interactions. Water isotherms in proteins are measured at different temperatures via the in-situ NMR technique. Water is found to interact differently with hydrophilic and hydrophobic groups on the protein. Water adsorption on hydrophilic groups is hardly affected by the temperature, while water adsorption on hydrophobic groups strongly depends on the temperature around 10 C, below which the adsorption is substantially reduced. This effect is induced by the dramatic decrease in the protein flexibility below 10 C. Furthermore, nanosecond to microsecond protein dynamics and the free energy, enthalpy, and entropy of protein hydration are studied as a function of hydration level and temperature. A crossover at 10 C in protein dynamics and thermodynamics is revealed. The effect of water at hydrophilic groups on protein dynamics and thermodynamics shows little temperature dependence, whereas water at hydrophobic groups has stronger effect above 10 C. In addition, I investigate the role of water in alcohol binding to the protein using the in-situ NMR detection. The isotherms of alcohols are first measured on dry proteins, then on proteins with a series of controlled hydration levels. The free energy, enthalpy, and entropy of alcohol binding are also determined. Two distinct types of alcohol binding are identified. On the one hand, alcohols can directly bind to a few specific sites on the protein. This type of binding is independent of temperature and can be

  5. A positron annihilation study of hydrated DNA

    DEFF Research Database (Denmark)

    Warman, J. M.; Eldrup, Morten Mostgaard

    1986-01-01

    Positron annihilation measurements are reported for hydrated DNA as a function of water content and as a function of temperature (20 to -180.degree. C) for samples containing 10 and 50% wt of water. The ortho-positronium mean lifetime and its intensity show distinct variations with the degree...

  6. Theoretical description of biomolecular hydration - Application to A-DNA

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, A.E.; Hummer, G. [Los Alamos National Laboratory, NM (United States); Soumpasis, D.M. [Max Planck Inst. for Biophysical Chemistry, Goettingen (Germany)

    1994-12-31

    The local density of water molecules around a biomolecule is constructed from calculated two- and three-points correlation functions of polar solvents in water using a Potential-of-Mean-Force (PMF) expansion. As a simple approximation, the hydration of all polar (including charged) groups in a biomolecule is represented by the hydration of water oxygen in bulk water, and the effect of non-polar groups on hydration are neglected, except for excluded volume effects. Pair and triplet correlation functions are calculated by molecular dynamics simulations. We present calculations of the structural hydration for ideal A-DNA molecules with sequences [d(CG){sub 5}]{sub 2} and [d(C{sub 5}G{sub 5})]{sub 2}. We find that this method can accurately reproduce the hydration patterns of A-DNA observed in neutron diffraction experiments on oriented DNA fibers.

  7. Theoretical description of biomolecular hydration - Application to A-DNA

    International Nuclear Information System (INIS)

    Garcia, A.E.; Hummer, G.; Soumpasis, D.M.

    1994-01-01

    The local density of water molecules around a biomolecule is constructed from calculated two- and three-points correlation functions of polar solvents in water using a Potential-of-Mean-Force (PMF) expansion. As a simple approximation, the hydration of all polar (including charged) groups in a biomolecule is represented by the hydration of water oxygen in bulk water, and the effect of non-polar groups on hydration are neglected, except for excluded volume effects. Pair and triplet correlation functions are calculated by molecular dynamics simulations. We present calculations of the structural hydration for ideal A-DNA molecules with sequences [d(CG) 5 ] 2 and [d(C 5 G 5 )] 2 . We find that this method can accurately reproduce the hydration patterns of A-DNA observed in neutron diffraction experiments on oriented DNA fibers

  8. Ethylene Separation via Hydrate Formation in W/O Emulsions

    Directory of Open Access Journals (Sweden)

    Yong Pan

    2015-05-01

    Full Text Available An hybrid absorption-hydration method was adopted to recover C2H4 from C2H4/CH4 binary gas mixtures and the hydrate formation conditions of C2H4/CH4 mixtures was studied experimentally in diesel in water (w/o emulsions. Span 20 at a concentration of 1.0 wt% in the aqueous phase was added to form water in diesel emulsions before hydrate formation and then hydrate in diesel slurry was separated after hydrate formation. The influences of initial gas-liquid volume ratio (53–142, pressure (3.4–5.4 MPa, temperature (274.15–278.15 K, water cuts (10–30 vol%, and the mole fraction of C2H4 in feed gas (13.19–80.44 mol% upon the C2H4 separation efficiency were systematically investigated. The experimental results show that ethylene can be enriched in hydrate slurry phase with high separation factor (S and recovery ratio (R. Most hydrate formation finished in 20 min, after that, the hydrate formation rate became very slow. The conclusion is useful for determining the suitable operation conditions when adopting an absorption-hydration method to separate C2H4/CH4.

  9. Daytime Changes of Skin Biophysical Characteristics: A Study of Hydration, Transepidermal Water Loss, pH, Sebum, Elasticity, Erythema, and Color Index on Middle Eastern Skin.

    Science.gov (United States)

    Firooz, Alireza; Zartab, Hamed; Sadr, Bardia; Bagherpour, Leili Naraghi; Masoudi, Aidin; Fanian, Ferial; Dowlati, Yahya; Ehsani, Amir Hooshang; Samadi, Aniseh

    2016-01-01

    The exposure of skin to ultraviolet radiation and temperature differs significantly during the day. It is reasonable that biophysical parameters of human skin have periodic daily fluctuation. The objective of this study was to study the fluctuations of various biophysical characteristics of Middle Eastern skin in standardized experimental conditions. Seven biophysical parameters of skin including stratum corneum hydration, transepidermal water loss, pH, sebum, elasticity, skin color, and erythema index were measured at three time points (8 a.m., 12 p.m. and 4 p.m.) on the forearm of 12 healthy participants (mean age of 28.4 years) without any ongoing skin disease using the CK MPA 580 device in standard temperature and humidity conditions. A significant difference was observed between means of skin color index at 8 a.m. (175.42 ± 13.92) and 4 p.m. (164.44 ± 13.72, P = 0.025), between the pH at 8 a.m. (5.72 ± 0.48) and 4 p.m. (5.33 ± 0.55, P = 0.001) and pH at 12 p.m. (5.60 ± 0.48) and 4 p.m. (5.33 ± 0.55, P = 0.001). Other comparisons between the means of these parameters at different time points resulted in nonsignificant P values. There are daytime changes in skin color index and pH. Skin color index might be higher and cutaneous pH more basic in the early morning compared to later of the day.

  10. Daytime changes of skin biophysical characteristics: A study of hydration, transepidermal water loss, ph, sebum, elasticity, erythema, and color index on middle eastern skin

    Directory of Open Access Journals (Sweden)

    Alireza Firooz

    2016-01-01

    Full Text Available Background: The exposure of skin to ultraviolet radiation and temperature differs significantly during the day. It is reasonable that biophysical parameters of human skin have periodic daily fluctuation. The objective of this study was to study the fluctuations of various biophysical characteristics of Middle Eastern skin in standardized experimental conditions. Materials and Methods: Seven biophysical parameters of skin including stratum corneum hydration, transepidermal water loss, pH, sebum, elasticity, skin color, and erythema index were measured at three time points (8 a.m., 12 p.m. and 4 p.m. on the forearm of 12 healthy participants (mean age of 28.4 years without any ongoing skin disease using the CK MPA 580 device in standard temperature and humidity conditions. Results: A significant difference was observed between means of skin color index at 8 a.m. (175.42 ± 13.92 and 4 p.m. (164.44 ± 13.72, P = 0.025, between the pH at 8 a.m. (5.72 ± 0.48 and 4 p.m. (5.33 ± 0.55, P = 0.001 and pH at 12 p.m. (5.60 ± 0.48 and 4 p.m. (5.33 ± 0.55, P = 0.001. Other comparisons between the means of these parameters at different time points resulted in nonsignificant P values. Conclusion: There are daytime changes in skin color index and pH. Skin color index might be higher and cutaneous pH more basic in the early morning compared to later of the day.

  11. 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

  12. Analysis of Decomposition for Structure I Methane Hydrate by Molecular Dynamics Simulation

    Science.gov (United States)

    Wei, Na; Sun, Wan-Tong; Meng, Ying-Feng; Liu, An-Qi; Zhou, Shou-Wei; Guo, Ping; Fu, Qiang; Lv, Xin

    2018-05-01

    Under multi-nodes of temperatures and pressures, microscopic decomposition mechanisms of structure I methane hydrate in contact with bulk water molecules have been studied through LAMMPS software by molecular dynamics simulation. Simulation system consists of 482 methane molecules in hydrate and 3027 randomly distributed bulk water molecules. Through analyses of simulation results, decomposition number of hydrate cages, density of methane molecules, radial distribution function for oxygen atoms, mean square displacement and coefficient of diffusion of methane molecules have been studied. A significant result shows that structure I methane hydrate decomposes from hydrate-bulk water interface to hydrate interior. As temperature rises and pressure drops, the stabilization of hydrate will weaken, decomposition extent will go deep, and mean square displacement and coefficient of diffusion of methane molecules will increase. The studies can provide important meanings for the microscopic decomposition mechanisms analyses of methane hydrate.

  13. 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.

  14. 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.

  15. Calculation of amorphous silica solubilities at 25° to 300°C and apparent cation hydration numbers in aqueous salt solutions using the concept of effective density of water

    Science.gov (United States)

    Fournier, Robert O.; Williams, Marshall L.

    1983-01-01

    The solubility of amorphous silica in aqueous salt solutions at 25° to 300°C can be calculated using information on its solubility in pure water and a model in which the activity of water in the salt solution is defined to equal the effective density. pe, of “free” water in that solution. At temperatures of 100°C and above, pe closely equals the product of the density of the solution times the weight fraction of water in the solution. At 25°C, a correction parameter must be applied to pe that incorporates a term called the apparent cation hydration number, h. Because of the many assumptions and other uncertainties involved in determining values of h, by the model used here, the reported numbers are not necessarily real hydration numbers even though they do agree with some published values determined by activity and diffusion methods. Whether or not h is a real hydration number, it would appear to be useful in its inclusion within a more extensive activity coefficient term that describes the departure of silica solubilities in concentrated salt solutions from expected behavior according to the model presented here. Values of h can be calculated from measured amorphous silica solubilities in salt solutions at 25°C provided there is no complexing of dissolved silica with the dissolved salt, or if the degree of complexing is known. The previously postulated aqueous silica-sulfate complexing in aqueous Na2SO4 solutions is supported by results of the present effective density of water model

  16. Enzyme hydration, activity and flexibility : A neutron scattering approach

    International Nuclear Information System (INIS)

    Kurkal-Siebert, V.; Finney, J.L.; Daniel, R.M.; Smith, Jeremy C.

    2006-01-01

    Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. The question of whether the hydration-induced enzyme flexibility is important for activity is addressed by performing picosecond dynamic neutron scattering experiments on pig liver esterase powders at various temperatures as well as solutions. At all temperatures and hydrations investigated here, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. At low temperature, increasing hydration resulted in lower flexibility of the enzyme. At higher temperatures, systems containing sufficient number of water molecules interacting with the protein exhibit increased flexibility. The implication of these results is that, although the additional hydration-induced diffusive motion and flexibility at high temperatures in the enzyme detected here may be related to increased activity, they are not required for the enzyme to function

  17. Dissolution mechanisms of CO2 hydrate droplets in deep seawaters

    International Nuclear Information System (INIS)

    Gabitto, Jorge; Tsouris, Costas

    2006-01-01

    Carbon dioxide dissolution at intermediate ocean depths was studied using physical and mass transfer models. Particle density and hydrate layer thickness were determined using existing field data. Pseudo-homogeneous and heterogeneous mass transfer models were proposed to study the dissolution process. Pseudo-homogeneous models do not seem to represent the dissolution process well. Although heterogeneous models interpret the physical behavior better, unresolved issues related to hydrate dissolution still remain. For example, solid hydrate forms on one side of the hydrate film while it dissolves on the other. Dissolution is a complex process that comprises at least two sequential steps. The global process is controlled by mass transfer inside the hydrate layer or by a dissolution reaction at the hydrate-water interface

  18. Manufacture of Methane Hydrate using Carbon Nano Tubes

    International Nuclear Information System (INIS)

    Park, Sung Seek

    2010-02-01

    Methane hydrate is formed by physical binding between water molecule and gas such as methane, ethane, propane, or carbon dioxide, etc., which is captured in the cavities of water molecule under the specific temperature and pressure. More than 99% of naturally produced methane hydrate consists of methane, and is widely dispersed in the continental slope and continental Shelf of the Pacific and the Atlantic, the Antarctica etc. The reserve of fossil fuel is 500 billion carbon ton and the reserve of methane is 360 million carbon ton. The reserve of gas hydrate is more than 1 trillion carbon ton, which is twice the fossil fuel. Therefore, natural gas hydrate as a kind of gas hydrate is expected to replace fossil fuel as new energy source of 21st century. Also 1 m 3 hydrate of pure methane can be decomposed to the maximum of 216 m 3 methane at standard condition. If these characteristics of hydrate are reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store natural gas in large quantity. Especially the transportation cost is known to be 18∼25% less than the liquefied transportation. However, when natural gas hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. Therefore, for the practical purpose in the application, the present investigation focuses on the rapid production of hydrates and increases gas consumption by adding MWCNT and NaCl into pure water. The results show that the equilibrium pressure in seawater is more higher than that in pure water, and methane hydrate could be formed rapidly during pressurization if the subcooling is maintained at 9K or above in seawater and 8K or above in pure water, respectively. Also, amount of consumed gas volume in pure water is more higher that in seawater at the same experimental conditions

  19. 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

  20. Carbon dioxide gas hydrates accumulation in freezing and frozen sediments

    Energy Technology Data Exchange (ETDEWEB)

    Chuvilin, E.; Guryeva, O. [Moscow State Univ., Moscow (Russian Federation). Dept. of Geology

    2008-07-01

    Carbon dioxide (CO{sub 2}) hydrates and methane hydrates can be formed, and exist under natural conditions. The permafrost area has been considered as an environment for the potential disposal of CO{sub 2}. The favorable factors for preserving CO{sub 2} in liquid and gas hydrate states in frozen sediments and under permafrost horizons are great thickness of frozen sediments; low permeability in comparison with thawed sediments; and favourable conditions for hydrates formation. Therefore, research on the formation and existence conditions of CO{sub 2} gas hydrates in permafrost and under permafrost sediments are of great importance for estimation of CO{sub 2} disposal conditions in permafrost, and for working out specific sequestration schemes. This paper presented the results of an experimental study on the process of carbon dioxide (CO{sub 2}) gas hydrates formation in the porous media of sediments under positive and negative temperatures. Sediment samples of various compositions including those selected in the permafrost area were used. The research was conducted in a special pressure chamber, which allowed to monitor pressure and temperature. The study used the monitoring results in order to make quantitative estimation of the kinetics of CO{sub 2} hydrates accumulation in the model sediments. Results were presented in terms of kinetics of CO{sub 2} hydrates accumulation in the porous media at positive and negative temperatures; kinetics of CO{sub 2} hydrates accumulation in various porous media; gas hydrate-former influence on kinetics of hydrates accumulation in frozen sediments; and influence of freezing on CO{sub 2} hydrates accumulation in porous media. It was concluded that hydrate accumulation took an active place in porous media not only under positive, but also under high negative temperatures, when the water was mainly in the form of ice in porous media. 27 refs., 3 tabs., 5 figs.

  1. The effect of stereochemistry on carbohydrate hydration in aqueous solutions

    NARCIS (Netherlands)

    Galema, Saskia Alexandra

    1992-01-01

    Although-carbohydrates are widely used, not much is known about the stereochemical aspects of hydration of carbohydrates. For D-aldohexoses, for example, there are eight different stereoisomers. Just how the hydroxy topology of a carbohydrate molecule influences the hydration behaviour in water is

  2. Phase equilibrium condition of marine carbon dioxide hydrate

    International Nuclear Information System (INIS)

    Sun, Shi-Cai; Liu, Chang-Ling; Ye, Yu-Guang

    2013-01-01

    Highlights: ► CO 2 hydrate phase equilibrium was studied in simulated marine sediments. ► CO 2 hydrate equilibrium temperature in NaCl and submarine pore water was depressed. ► Coarse-grained silica sand does not affect CO 2 hydrate phase equilibrium. ► The relationship between equilibrium temperature and freezing point was discussed. - Abstract: The phase equilibrium of ocean carbon dioxide hydrate should be understood for ocean storage of carbon dioxide. In this paper, the isochoric multi-step heating dissociation method was employed to investigate the phase equilibrium of carbon dioxide hydrate in a variety of systems (NaCl solution, submarine pore water, silica sand + NaCl solution mixture). The experimental results show that the depression in the phase equilibrium temperature of carbon dioxide hydrate in NaCl solution is caused mainly by Cl − ion. The relationship between the equilibrium temperature and freezing point in NaCl solution was discussed. The phase equilibrium temperature of carbon dioxide hydrate in submarine pore water is shifted by −1.1 K to lower temperature region than that in pure water. However, the phase equilibrium temperature of carbon dioxide hydrate in mixture samples of coarsed-grained silica sand and NaCl solution is in agreement with that in NaCl solution with corresponding concentrations. The relationship between the equilibrium temperature and freezing point in mixture samples was also discussed.

  3. The U.S. Geological Survey’s Gas Hydrates Project

    Science.gov (United States)

    Ruppel, Carolyn D.

    2018-01-17

    The Gas Hydrates Project at the U.S. Geological Survey (USGS) focuses on the study of methane hydrates in natural environments. The project is a collaboration between the USGS Energy Resources and the USGS Coastal and Marine Geology Programs and works closely with other U.S. Federal agencies, some State governments, outside research organizations, and international partners. The USGS studies the formation and distribution of gas hydrates in nature, the potential of hydrates as an energy resource, and the interaction between methane hydrates and the environment. The USGS Gas Hydrates Project carries out field programs and participates in drilling expeditions to study marine and terrestrial gas hydrates. USGS scientists also acquire new geophysical data and sample sediments, the water column, and the atmosphere in areas where gas hydrates occur. In addition, project personnel analyze datasets provided by partners and manage unique laboratories that supply state-of-the-art analytical capabilities to advance national and international priorities related to gas hydrates.

  4. Kinetic Hydration Heat Modeling for High-Performance Concrete Containing Limestone Powder

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone powder is increasingly used in producing high-performance concrete in the modern concrete industry. Limestone powder blended concrete has many advantages, such as increasing the early-age strength, reducing the setting time, improving the workability, and reducing the heat of hydration. This study presents a kinetic model for modeling the hydration heat of limestone blended concrete. First, an improved hydration model is proposed which considers the dilution effect and nucleation effect due to limestone powder addition. A degree of hydration is calculated using this improved hydration model. Second, hydration heat is calculated using the degree of hydration. The effects of water to binder ratio and limestone replacement ratio on hydration heat are clarified. Third, the temperature history and temperature distribution of hardening limestone blended concrete are calculated by combining hydration model with finite element method. The analysis results generally agree with experimental results of high-performance concrete with various mixing proportions.

  5. Hydration study of ordinary portland cement in the presence of zinc ions

    Directory of Open Access Journals (Sweden)

    Monica Adriana Trezza

    2007-12-01

    Full Text Available Hydration products of Portland cement pastes, hydrated in water and in the presence of zinc ions were studied comparatively at different ages. Hydration products were studied by X ray diffractions (XRD and infrared spectroscopy (IR. Although IR is not frequently used in cement chemistry, it evidenced a new phase Ca(Zn(OH32. 2H2O formed during cement hydration in the presence of zinc. The significant retardation of early cement hydration in the presence of zinc is assessed in detail by differential calorimetry as a complement to the study carried out by IR and XRD, providing evidence that permits to evaluate the kinetic of the early hydration.

  6. Fuel cell membrane hydration and fluid metering

    Science.gov (United States)

    Jones, Daniel O.; Walsh, Michael M.

    1999-01-01

    A hydration system includes fuel cell fluid flow plate(s) and injection port(s). Each plate has flow channel(s) with respective inlet(s) for receiving respective portion(s) of a given stream of reactant fluid for a fuel cell. Each injection port injects a portion of liquid water directly into its respective flow channel in order to mix its respective portion of liquid water with the corresponding portion of the stream. This serves to hydrate at least corresponding part(s) of a given membrane of the corresponding fuel cell(s). The hydration system may be augmented by a metering system including flow regulator(s). Each flow regulator meters an injecting at inlet(s) of each plate of respective portions of liquid into respective portion(s) of a given stream of fluid by corresponding injection port(s).

  7. Multicavity SCRF calculation of ion hydration energies

    International Nuclear Information System (INIS)

    Diercksen, B.H.F.; Karelson, M.; Tamm, T.

    1994-01-01

    The hydration energies of the proton, hydroxyl ion, and several inorganic ions were calculated using the multicavity self-consistent reaction field (MCa SCRF) method developed for the quantum-mechanical modeling of rotationally or flexible systems in dielectric media. The ionic complexes H 3 O + (H2O) 4 , OH - (H2O) 4 , NH + 4 (H2O) 4 , and Hal - (H2O) 4 , where Hal = F, Cl, or Br, have been studied. Each complex was divided between five spheres, corresponding to the central ion and four water molecules in their first coordination sphere, respectively. Each cavity was surrounded by a polarizable medium with the dielectric permittivity of water at room temperature (80). The ionic hydration energies of ions were divided into specific and nonspecific parts. After accounting for the cavity-formation energy using scaled particle theory, good agreement between the total calculated and experimental hydration energies was obtained for all ions studied

  8. THz characterization of hydrated and anhydrous materials

    Science.gov (United States)

    Sokolnikov, Andre

    2011-06-01

    The characterization of anhydrous and hydrated forms of materials is of great importance to science and industry. Water content poses difficulties for successful identification of the material structure by THz radiation. However, biological tissues and hydrated forms of nonorganic substances still may be investigated by THz radiation. This paper outlines the range of possibilities of the above characterization, as well as provides analysis of the physical mechanism that allows or prevents penetration of THz waves through the substance. THz-TDS is used to measure the parameters of the characterization of anhydrous and hydrated forms of organic and nonorganic samples. Mathematical methods (such as prediction models of time-series analysis) are used to help identifying the absorption coefficient and other parameters of interest. The discovered dependencies allow designing techniques for material identification/characterization (e.g. of drugs, explosives, etc. that may have water content). The results are provided.

  9. Reflective terahertz (THz) imaging: system calibration using hydration phantoms

    Science.gov (United States)

    Bajwa, Neha; Garritano, James; Lee, Yoon Kyung; Tewari, Priyamvada; Sung, Shijun; Maccabi, Ashkan; Nowroozi, Bryan; Babakhanian, Meghedi; Sanghvi, Sajan; Singh, Rahul; Grundfest, Warren; Taylor, Zachary

    2013-02-01

    Terahertz (THz) hydration sensing continues to gain traction in the medical imaging community due to its unparalleled sensitivity to tissue water content. Rapid and accurate detection of fluid shifts following induction of thermal skin burns as well as remote corneal hydration sensing have been previously demonstrated in vivo using reflective, pulsed THz imaging. The hydration contrast sensing capabilities of this technology were recently confirmed in a parallel 7 Tesla Magnetic Resonance (MR) imaging study, in which burn areas are associated with increases in local mobile water content. Successful clinical translation of THz sensing, however, still requires quantitative assessments of system performance measurements, specifically hydration concentration sensitivity, with tissue substitutes. This research aims to calibrate the sensitivity of a novel, reflective THz system to tissue water content through the use of hydration phantoms for quantitative comparisons of THz hydration imagery.Gelatin phantoms were identified as an appropriate tissue-mimicking model for reflective THz applications, and gel composition, comprising mixtures of water and protein, was varied between 83% to 95% hydration, a physiologically relevant range. A comparison of four series of gelatin phantom studies demonstrated a positive linear relationship between THz reflectivity and water concentration, with statistically significant hydration sensitivities (p hydration). The THz-phantom interaction is simulated with a three-layer model using the Transfer Matrix Method with agreement in hydration trends. Having demonstrated the ability to accurately and noninvasively measure water content in tissue equivalent targets with high sensitivity, reflective THz imaging is explored as a potential tool for early detection and intervention of corneal pathologies.

  10. Hydration in soccer: a review

    Directory of Open Access Journals (Sweden)

    Monteiro Cristiano Ralo

    2003-01-01

    Full Text Available Hydration should be considered before, during and after the exercise. This review intends to approach the main points of hydration process in soccer. The replacement of fluids during exercise is proportional to some factors, such as: exercise intensity; climatic conditions; the athlete's acclimatization; the athlete's physical conditioning; physiologic individual characteristics and the player's biomechanics. Performance is improved when players ingest not only water but also carbohydrate. The rates that carbohydrate and water are absorbed by the organism are limited by the rates of gastric emptying and intestinal absorption. The composition of drinks offered to the players should be influenced by the relative importance of the need of supplying carbohydrates or water; it should be remembered that the depletion of carbohydrate can result in fatigue and decrease of performance, but it is not usually a life-threatening condition. The addition of carbohydrate in these drinks increases the concentrations of blood glucose, increases the use of external fuel through the increase of the glucose oxidation in the muscles and it spares muscle glycogen. So, the ingestion of carbohydrate before and during the exercise can delay the emergence of fatigue and increase the players' performance. Several tactics can be used to avoid dehydration, like hyperhydration before exercise and player's acclimatization. The ideal situation to restore the player's fluid losses is between the sessions of exercises. Since soccer is a sport with quite peculiar characteristics related to hydration, the players should be concerned and educated about the importance of fluid ingestion before, during and after the exercise.

  11. Effects of organic solvent, water activity, and salt hydrate pair on the sn-1,3 selectivity and activity of whole-cell lipase from Aspergillus niger GZUF36.

    Science.gov (United States)

    Li, Cuiqin; Zhang, Fuhao; Gao, Zexin; He, Laping; Zeng, Xuefeng; Zhu, Qiujin; Yu, Lijuan

    2018-01-01

    We previously screened a whole-cell lipase EC 3.1.1.3 from the novel strain Aspergillus niger GZUF36, which exhibited 1,3-selectivity in the synthesis of 1,3-diacylglycerol via glycerolysis. However, the mechanism of lipase selectively in catalyzing the sn-1,3 position remains ambiguous. This work was performed to investigate the 1,3-selective mechanism of lipase using glycerolysis to synthesize 1,3-diacylglycerol (1,3-DG) as a model reaction by changing solvent(s) and water activity (a w ), and addition of salt hydrate pair. The measured diacylglycerol yield was also used to examine lipase activity. Results indicated that not only organic solvent and a w have strong effect on the sn-1,3 selectivity, but also ions of salt hydrate pair also affected selectivity. Lipase conformation was altered by hydrophobic interactions of the solvent, a w , or ions of salt hydrate, resulting in distinct sn-1,3 selectivity of the lipase. The salt hydrate pair changed the lipase conformation and selectivity not only by a w but also by static interactions, which was rarely reported. These parameters also affected lipase activity. The lipase displayed the highest selectivity (about 88%) and activity in solvents of t-butanol and n-hexane (1:29, v/v) at a w 0.43. The results demonstrated that the sn-1,3 selectivity and activity of the lipase from A. niger GZUF36 may be improved by control of some crucial factors. This work laid a foundation for the application of lipase in the synthesis of 1,3-DG and other structural and functional lipids.

  12. 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

  13. Effect of localized water uptake on backfill hydration and water movement in a backfilled tunnel: half-scale tests at Aespoe Bentonite Laboratory

    International Nuclear Information System (INIS)

    Dixon, D.; Jonsson, E.; Hansen, J.; Hedin, M.; Ramqvist, G.

    2011-04-01

    The report describes the outcome of the work within the project 'SU508.20 Impact of water inflow in deposition tunnels'. Project decision SKB doc 1178871 Version 3.0. Two activity plans have been used for the field work: AP TD SU50820-09-019 and AP TD SU 50820-09-071. SKB and Posiva have been examining those processes that may have particularly strong effects on the evolution of a newly backfilled deposition tunnel in a KBS-3V repository. These assessments have involved the conduct of increasingly large and complex laboratory tests and simulations of a backfilled tunnel section. In this series of four tests, the effect of water inflow into a backfilled tunnel section via an intersecting fracture feature was evaluated. The tests included the monitoring of mock-ups where water entered via the simulated fractures as well as evaluation of what the effect of isolated tunnel sections caused by localized water inflow would have on subsequent evolution of these isolated sections. It was found that even a slowly seeping fracture can have a substantial effect on the backfill evolution as it will cause development of a gasket-like feature that effectively cuts of air and water movement from inner to outer regions of the backfilled tunnel. Water entering via these fractures will ultimately move out of the tunnel via a single discrete flow path, in a manner similar to what was observed in previous 1/2-scale and smaller simulations. If the low-rate of water inflow from fracture is the only source of water inflow to the tunnel this will result in hydraulic behaviour similar to that observed for a single inflow point in previous tests. The presence of a fracture feature will however result in a larger proportion of water uptake by the process of suction than might occur in a point inflow situation and hence a more uniform water distribution will be present in the pellet fill. This also results in a greater tendency for water to be absorbed into the adjacent block fill material and

  14. Effect of localized water uptake on backfill hydration and water movement in a backfilled tunnel: half-scale tests at Aespoe Bentonite Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, D. [Atomic Energy of Canada Limited, Chalk River (Canada); Jonsson, E. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Hansen, J. [Posiva Oy, Olkiluoto (Finland); Hedin, M. [Aangpannefoereningen, Stockholm (Sweden); Ramqvist, G. [Eltekno AB, Figeholm (Sweden)

    2011-04-15

    The report describes the outcome of the work within the project 'SU508.20 Impact of water inflow in deposition tunnels'. Project decision SKB doc 1178871 Version 3.0. Two activity plans have been used for the field work: AP TD SU50820-09-019 and AP TD SU 50820-09-071. SKB and Posiva have been examining those processes that may have particularly strong effects on the evolution of a newly backfilled deposition tunnel in a KBS-3V repository. These assessments have involved the conduct of increasingly large and complex laboratory tests and simulations of a backfilled tunnel section. In this series of four tests, the effect of water inflow into a backfilled tunnel section via an intersecting fracture feature was evaluated. The tests included the monitoring of mock-ups where water entered via the simulated fractures as well as evaluation of what the effect of isolated tunnel sections caused by localized water inflow would have on subsequent evolution of these isolated sections. It was found that even a slowly seeping fracture can have a substantial effect on the backfill evolution as it will cause development of a gasket-like feature that effectively cuts of air and water movement from inner to outer regions of the backfilled tunnel. Water entering via these fractures will ultimately move out of the tunnel via a single discrete flow path, in a manner similar to what was observed in previous 1/2-scale and smaller simulations. If the low-rate of water inflow from fracture is the only source of water inflow to the tunnel this will result in hydraulic behaviour similar to that observed for a single inflow point in previous tests. The presence of a fracture feature will however result in a larger proportion of water uptake by the process of suction than might occur in a point inflow situation and hence a more uniform water distribution will be present in the pellet fill. This also results in a greater tendency for water to be absorbed into the adjacent block fill

  15. Distribution of gas hydrate inhibitor monoethylene glycol in condensate and water systems: Experimental measurement and thermodynamic modeling using the cubic-plus-association equation of state

    DEFF Research Database (Denmark)

    Riaz, Muhammad; Yussuf, Mustafe A.; Frost, Michael

    2014-01-01

    The deepwater energy sector represents one of the major growth areas of the oil and gas industry today. To meet the challenges of hydrate formation, corrosion, scaling, and foaming, the oil and gas industry uses many chemicals and their use has increased significantly over the years. To inhibit gas...

  16. Protein-solvent preferential interactions, protein hydration, and the modulation of biochemical reactions by solvent components.

    Science.gov (United States)

    Timasheff, Serge N

    2002-07-23

    Solvent additives (cosolvents, osmolytes) modulate biochemical reactions if, during the course of the reaction, there is a change in preferential interactions of solvent components with the reacting system. Preferential interactions can be expressed in terms of preferential binding of the cosolvent or its preferential exclusion (preferential hydration). The driving force is the perturbation by the protein of the chemical potential of the cosolvent. It is shown that the measured change of the amount of water in contact with protein during the course of the reaction modulated by an osmolyte is a change in preferential hydration that is strictly a measure of the cosolvent chemical potential perturbation by the protein in the ternary water-protein-cosolvent system. It is not equal to the change in water of hydration, because water of hydration is a reflection strictly of protein-water forces in a binary system. There is no direct relation between water of preferential hydration and water of hydration.

  17. Methane hydrate induced permeability modification for multiphase flow in unsaturated porous media

    Science.gov (United States)

    Seol, Yongkoo; Kneafsey, Timothy J.

    2011-08-01

    An experimental study was performed using X-ray computed tomography (CT) scanning to capture three-dimensional (3-D) methane hydrate distributions and potential discrete flow pathways in a sand pack sample. A numerical study was also performed to develop and analyze empirical relations that describe the impacts of hydrate accumulation habits within pore space (e.g., pore filling or grain cementing) on multiphase fluid migration. In the experimental study, water was injected into a hydrate-bearing sand sample that was monitored using an X-ray CT scanner. The CT images were converted into numerical grid elements, providing intrinsic sample data including porosity and phase saturations. The impacts of hydrate accumulation were examined by adapting empirical relations into the flow simulations as additional relations governing the evolution of absolute permeability of hydrate bearing sediment with hydrate deposition. The impacts of pore space hydrate accumulation habits on fluid migration were examined by comparing numerical predictions with experimentally measured water saturation distributions and breakthrough curves. A model case with 3-D heterogeneous initial conditions (hydrate saturation, porosity, and water saturation) and pore body-preferred hydrate accumulations best captured water migration behavior through the hydrate-bearing sample observed in the experiment. In the best matching model, absolute permeability in the hydrate bearing sample does not decrease significantly with increasing hydrate saturation until hydrate saturation reaches about 40%, after which it drops rapidly, and complete blockage of flow through the sample can occur as hydrate accumulations approach 70%. The result highlights the importance of permeability modification due to hydrate accumulation habits when predicting multiphase flow through high-saturation, reservoir quality hydrate-bearing sediments.

  18. Gas hydrate resource quantification in Uruguay

    International Nuclear Information System (INIS)

    Tomasini, J.; De Santa Ana, H.; Veroslavsky, G.

    2012-01-01

    The gas hydrates are crystalline solids formed by natural gas (mostly methane) and water, which are stable in thermobaric conditions given under high pressures and low temperatures. These conditions are given in permafrost zones and continental margin basins offshore in the nature

  19. 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

  20. Gold(III)-Catalyzed Hydration of Phenylacetylene

    Science.gov (United States)

    Leslie, J. Michelle; Tzeel, Benjamin A.

    2016-01-01

    A guided inquiry-based experiment exploring the regioselectivity of the hydration of phenylacetylene is described. The experiment uses an acidic gold(III) catalyst in a benign methanol/water solvent system to introduce students to alkyne chemistry and key principles of green chemistry. The experiment can be easily completed in approximately 2 h,…

  1. Effect of the sulphur atom on geometry and spectra of the biomolecule 2-thiouracil and in the WC base pair 2-thiouridine-adenosine. Influence of water in the first hydration shell.

    Science.gov (United States)

    Alcolea Palafox, M; Rastogi, V K; Singh, S P

    2018-04-01

    The effect of the sulphur atom on 2-thiouracil (2TU) and 2-thiouridine molecules, as compared with uracil and uridine molecules, respectively, was carried out in several environments. The predicted IR spectrum of 2TU in the isolated state was compared with that obtained for uracil molecule and with those reported experimentally in matrix isolation. Its crystal unit cell in the solid state was simulated through a tetramer form using DFT methods for the first time. The calculated Raman spectrum was compared to the experimental ones in the solid state. A linear scaling procedure was used for this task. The first hydration shell was simulated by explicit number of water molecules surrounding 2TU up to 30 and was compared with that obtained in uracil molecule. Water molecules 'distributed' around 2TU was preferred over that 'clustering', because it can better reproduce the hydration and their effects on different parameters of the molecular structure of 2TU and uracil. The total atomic charges and several calculated thermodynamic parameters were discussed. The effect of the sulphur atom on the Watson-Crick (WC) and reverse WC base pair uridine-adenosine was estimated, and the CP corrected interaction energies were calculated. 2-thiouridine has a weaker WC pair than that with uridine, although its slight higher dipole moment (μ) facilitates the interaction with the water molecules. Several helical parameters were determined.

  2. Experimental hydrate formation and gas production scenarios based on CO{sub 2} sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, J.C.; Howard, J.J. [ConocoPhillips, Bartlesville, OK (United States). Reservoir Laboratories; Baldwin, B.A. [Green Country Petrophysics LLC, Dewey, OK (United States); Ersland, G.; Husebo, J.; Graue, A. [Bergen Univ., Bergen (Norway). Dept. of Physics and Technology

    2008-07-01

    Gas hydrate production strategies have focused on depressurization or thermal stimulation of the reservoir, which in turn leads to hydrate dissociation. In order to evaluate potential production scenarios, the recovery efficiency of the natural gas from hydrate must be known along with the corresponding amounts of produced water. This study focused on the exchange of carbon dioxide (CO{sub 2}) with the natural gas hydrate and the subsequent release of free methane (CH{sub 4}). Laboratory experiments that investigated the rates and mechanisms of hydrate formation in coarse-grained porous media have shown the significance of initial water saturation and salinity on forming methane hydrates. Many of the experiments were performed in a sample holder fitted with an MRI instrument for monitoring hydrate formation. Hydrate-saturated samples were subjected to different procedures to release methane. The rates and efficiency of the exchange process were reproducible over a series of initial conditions. The exchange process was rapid and efficient in that no free water was observed in the core with MRI measurements. Injection of CO{sub 2} into the whole-core hydrate-saturated pore system resulted in methane production at the outlet end. Permeability measurements on these hydrate saturated cores during hydrate formation decreased to low values, but enough for gas transport. The lower permeability values remained constant during the methane-carbon dioxide exchange process in the hydrate structure. 12 refs., 9 figs.

  3. Study on gas hydrate as a new energy resource in the twenty first century

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Byung Jae; Kim, Won Sik; Oh, Jae Ho [Korea Institute of Geology Mining and Materials, Taejon (Korea)] [and others

    1998-12-01

    Methane hydrate, a special type of clathrate hydrates, is a metastable solid compound mainly consisted of methane and water and generally called as gas hydrate. It is stable in the specific low- temperature/high-pressure conditions. Very large amount of methane that is the main component of natural gas, is accumulated in the form of methane hydrate subaquatic areas. Methane hydrate are the major reservoir of methane on the earth. On the other hand, the development and transmission through pipeline of oil and natural gas in the permafrost and deep subaquatic regions are significantly complicated by formation and dissociation of methane hydrate. The dissociation of natural methane hydrates caused by increasing temperature and decreasing pressure could cause the atmospheric pollution and geohazard. The formation, stable existence and dissociation of natural methane hydrates depend on the temperature, pressure, and composition of gas and characteristics of the interstitial waters. For the study on geophysical and geological conditions for the methane hydrate accumulation and to find BSR in the East Sea, Korea, the geophysical surveys using air-gun system, multibeam echo sounder, SBP were implemented in last September. The water temperature data vs. depth were obtained to determine the methane hydrate stability zone in the study area. The experimental equilibrium condition of methane hydrate was also measured in 3 wt.% sodium chloride solution. The relationship between Methane hydrate formation time and overpressure was analyzed through the laboratory work. (author). 49 refs., 6 tabs., 26 figs.

  4. Methane hydrates in quaternary climate change

    International Nuclear Information System (INIS)

    Kennett, J. P.; Hill, T. M.; Behl, R. J.

    2005-01-01

    The hydrate reservoir in marine sediments is known to contain a large volume of exchangeable carbon stored as solid methane hydrate and associated free gas. This reservoir has been shown to be potentially unstable in response to changing intermediate water temperature and sea level (pressure). Evidence continues to grow for past episodes of major methane release at times of climatic warming. Yet few studies of late Quaternary climate change include methane hydrates as an integral part of the global climate system, in spite of the largest known oscillations at this time in sea level and upper ocean temperature changes for the Cenozoic or earlier, conditions that favor instability of the methane hydrate reservoir. Abrupt increases in atmospheric methane recorded in polar ice cores are widely believed to have resulted, not from ocean-floor methane degassing, but instead from continental wetland activation, a hypothesis thus far unsupported by geological data. Furthermore, as part of this Wetland Methane Hypothesis, the abrupt methane increases have been seen as a response to climatic warming rather than contributing significantly to the change. An alternative view (formulated as the Clathrate Gun Hypothesis) is that the speed, magnitude and timing of abrupt climate change in the recent geologic past are consistent with the process of major degassing of methane hydrates. We summarize aspects of this hypothesis here and needs to test this hypothesis. (Author)

  5. Characteristics of Methane Hydrate Formation in Artificial and Natural Media

    Directory of Open Access Journals (Sweden)

    Qingbai Wu

    2013-03-01

    Full Text Available The formation of methane hydrate in two significantly different media was investigated, using silica gel as an artificial medium and loess as a natural medium. The methane hydrate formation was observed through the depletion of water in the matrix, measured via the matrix potential and the relationship between the matrix potential and the water content was determined using established equations. The velocity of methane hydrate nucleation slowed over the course of the reaction, as it relied on water transfer to the hydrate surfaces with lower Gibbs free energy after nucleation. Significant differences in the reactions in the two types of media arose from differences in the water retention capacity and lithology of media due to the internal surface area and pore size distributions. Compared with methane hydrate formation in silica gel, the reaction in loess was much slower and formed far less methane hydrate. The results of this study will advance the understanding of how the properties of the environment affect the formation of gas hydrates in nature.

  6. Geomechanical Performance of Hydrate-Bearing Sediment in Offshore Environments

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Holditch; Tad Patzek; Jonny Rutqvist; George Moridis; Richard Plumb

    2008-03-31

    The objective of this multi-year, multi-institutional research project was to develop the knowledge base and quantitative predictive capability for the description of geomechanical performance of hydrate-bearing sediments (hereafter referred to as HBS) in oceanic environments. The focus was on the determination of the envelope of hydrate stability under conditions typical of those related to the construction and operation of offshore platforms. We have developed a robust numerical simulator of hydrate behavior in geologic media by coupling a reservoir model with a commercial geomechanical code. We also investigated the geomechanical behavior of oceanic HBS using pore-scale models (conceptual and mathematical) of fluid flow, stress analysis, and damage propagation. The objective of the UC Berkeley work was to develop a grain-scale model of hydrate-bearing sediments. Hydrate dissociation alters the strength of HBS. In particular, transformation of hydrate clusters into gas and liquid water weakens the skeleton and, simultaneously, reduces the effective stress by increasing the pore pressure. The large-scale objective of the study is evaluation of geomechanical stability of offshore oil and gas production infrastructure. At Lawrence Berkeley National Laboratory (LBNL), we have developed the numerical model TOUGH + Hydrate + FLAC3D to evaluate how the formation and disassociation of hydrates in seafloor sediments affects seafloor stability. Several technical papers were published using results from this model. LBNL also developed laboratory equipment and methods to produce realistic laboratory samples of sediments containing gas hydrates so that mechanical properties could be measured in the laboratory. These properties are required to run TOUGH + Hydrate + FLAC3D to evaluate seafloor stability issues. At Texas A&M University we performed a detailed literature review to determine what gas hydrate formation properties had been measured and reported in the literature. We

  7. Geo-scientific investigations of gas-hydrates in India

    Digital Repository Service at National Institute of Oceanography (India)

    Sain, K.; Gupta, H.; Mazumdar, A.; Bhaumik, A.K.; Bhowmick, P.K.

    The best solution to meet India's overwhelming energy requirement is to tap the nuclear and solar power to the maximum extent possible. Another feasible major energy resource is gas-hydrates (crystalline substances of methane and water) that have...

  8. Well log characterization of natural gas-hydrates

    Science.gov (United States)

    Collett, Timothy S.; Lee, Myung W.

    2012-01-01

    In the last 25 years there have been significant advancements in the use of well-logging tools to acquire detailed information on the occurrence of gas hydrates in nature: whereas wireline electrical resistivity and acoustic logs were formerly used to identify gas-hydrate occurrences in wells drilled in Arctic permafrost environments, more advanced wireline and logging-while-drilling (LWD) tools are now routinely used to examine the petrophysical nature of gas-hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. Resistivity- and acoustic-logging tools are the most widely used for estimating the gas-hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. 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. New well-logging tools designed to make directionally oriented acoustic and propagation-resistivity log measurements provide the data needed to analyze the acoustic and electrical anisotropic properties of both highly interbedded and fracture-dominated gas-hydrate reservoirs. Advancements in nuclear magnetic resonance (NMR) logging and wireline formation testing (WFT) also allow for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids(i.e., free water along with clay- and capillary-bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms

  9. 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.

  10. Methane hydrate distribution from prolonged and repeated formation in natural and compacted sand samples: X-ray CT observations

    Energy Technology Data Exchange (ETDEWEB)

    Rees, E.V.L.; Kneafsey, T.J.; Seol, Y.

    2010-07-01

    To study physical properties of methane gas hydrate-bearing sediments, it is necessary to synthesize laboratory samples due to the limited availability of cores from natural deposits. X-ray computed tomography (CT) and other observations have shown gas hydrate to occur in a number of morphologies over a variety of sediment types. To aid in understanding formation and growth patterns of hydrate in sediments, methane hydrate was repeatedly formed in laboratory-packed sand samples and in a natural sediment core from the Mount Elbert Stratigraphic Test Well. CT scanning was performed during hydrate formation and decomposition steps, and periodically while the hydrate samples remained under stable conditions for up to 60 days. The investigation revealed the impact of water saturation on location and morphology of hydrate in both laboratory and natural sediments during repeated hydrate formations. Significant redistribution of hydrate and water in the samples was observed over both the short and long term.

  11. 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

  12. Towards CO2 sequestration and applications of CO2 hydrates: the effects of tetrahydrofuran on the phase equilibria of CO2 hydrates

    International Nuclear Information System (INIS)

    Khalik, M.S.; Peters, C.J.

    2006-01-01

    The increasing quantity of carbon dioxide (CO 2 ) in the atmosphere has caused widespread global concerns. Capturing CO 2 from its sources and stored it in the form of gas hydrates and application of CO 2 hydrates are among the proposed methods to overcome this problem. In order to make hydrate-based process more attractive, the use of cyclic ethers as promoters is suggested to reduce the required hydrate formation pressure and enhancing the corresponding kinetic rate. In the present work, tetrahydrofuran (THF) is chosen as a hydrate promoter, participating in forming hydrates and produces mixed hydrate together with CO 2 . The pressure and temperature ranges of hydrate stability region are carefully determined through phase equilibrium measurement of the ternary CO 2 , tetrahydrofuran (THF) and water systems. From the experimental results, it is confirmed that the presence of THF in CO 2 + water systems will extend the hydrate formation region to higher temperature at a constant pressure. The extension of the hydrate stability region is depended on the overall concentration of the ternary system. Moreover, four-phase equilibrium of H-Lw-Lv-V is observed in the system, which may be due to a liquid phase split. In the region where the four-phase equilibrium exists, the ternary system loses its concentration dependency of the hydrate equilibrium conditions. (Author)

  13. Experimental Investigation into the Combustion Characteristics of Propane Hydrates in Porous Media

    Directory of Open Access Journals (Sweden)

    Xiang-Ru Chen

    2015-02-01

    Full Text Available The combustion characteristics of both pure propane hydrates and the mixtures of hydrates and quartz sands were investigated by combustion experiments. The flame propagation, flame appearance, burning time and temperature in different hydrate layers were studied. For pure propane hydrate combustion, the initial flame falls in the “premixed” category. The flame propagates very rapidly, mainly as a result of burnt gas expansion. The flame finally self-extinguishes with some proportion of hydrates remaining unburned. For the hydrate-sand mixture combustion, the flame takes the form of many tiny discontinuous flames appearing and disappearing at different locations. The burn lasts for a much shorter amount of time than pure hydrate combustion. High porosity and high hydrate saturation is beneficial to the combustion. The hydrate combustion is the combustion of propane gas resulting from the dissociation of the hydrates. In both combustion test scenarios, the hydrate-dissociated water plays a key role in the fire extinction, because it is the main resistance that restrains the heat transfer from the flame to the hydrates and that prevents the hydrate-dissociated gas from releasing into the combustion zone.

  14. 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

  15. 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.

  16. Gas hydrate phase equilibria measurement techniques and phase rule considerations

    International Nuclear Information System (INIS)

    Beltran, Juan G.; Bruusgaard, Hallvard; Servio, Phillip

    2012-01-01

    Highlights: → Inconsistencies found in hydrate literature. → Clarification to the number of variables needed to satisfy and justify equilibrium data. → Application of phase rule to mixed hydrate systems. → Thermodynamically consistent format to present data. - Abstract: A brief review of the Gibbs phase rule for non-reacting systems and its correct application to clathrate hydrates is presented. Clarification is provided for a common mistake found in hydrate phase-equilibria literature, whereby initial compositions are used as intensive variables to satisfy the Gibbs phase rule instead of the equilibrium values. The system of (methane + carbon dioxide + water) under (hydrate + liquid + vapor) equilibrium is used as a case study to illustrate key points and suggestions to improve experimental techniques are proposed.

  17. Prospects of gas hydrate presence in the Chukchi sea

    Directory of Open Access Journals (Sweden)

    Т. В. Матвеева

    2017-08-01

    Full Text Available The purpose of this study is to forecast the scale and distribution character of gas hydrate stability zone in the Chukchi Sea under simulated natural conditions and basing on these results to estimate resource potential of gas hydrates within this area. Three types of stability zone have been identified. A forecast map of gas hydrate environment and potentially gas hydrate-bearing water areas in the Chukchi Sea has been plotted to a scale of 1:5 000 000. Mapping of gas hydrate stability zone allowed to give a justified forecast based on currently available data on geologic, fluid dynamic, cryogenic, geothermal and pressure-temperature conditions of gas hydrate formation in the Chukchi Sea. It is the first forecast of such kind that focuses on formation conditions for hydrates of various types and compositions in the Arctic seas offshore Russia. Potential amount of gas, stored beneath the Chukchi Sea in the form of hydrates, is estimated based on mapping of their stability zone and falls into the interval of 7·1011-11.8·1013 m3.

  18. The formation of gas hydrates and the effect of inhibitiors on their ...

    African Journals Online (AJOL)

    Natural gas hydrate is a solid crystalline compound produced by combining water and gas and it is considered as the clathrates. Guest gas molecules are stuck insider the pores of water networks produced by hydrogen bonds between molecules of water. There are different ways to analyze the hydrate formation operating ...

  19. 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)

  20. Irrigation port hydration in phacoemulsification surgery

    Directory of Open Access Journals (Sweden)

    Suzuki H

    2018-01-01

    Full Text Available Hisaharu Suzuki,1 Yoichiro Masuda,2 Yuki Hamajima,1 Hiroshi Takahashi3 1Department of Ophthalmology, Nippon Medical School Musashikosugi Hospital, Kawasaki City, Kanagawa, 2Department of Ophthalmology, The Jikei University, Katsushika Medical Center, Tokyo, 3Department of Ophthalmology, Nippon Medical School, Tokyo, Japan Background: In most cases, hydration is performed by water injection into the stromal tissue with a needle. The technique is simple, however it is sometimes troublesome.Purpose: We describe a simple technique for hydrating the corneal stroma in cataract surgery using an irrigation port.Patients and methods: The technique began by pushing the irrigation port against the corneal stroma for a few seconds during phacoemulsification, which generated edema in the corneal incision that subsequently prevented leakage. This procedure is called the hydration using irrigation port (HYUIP technique. A total of 60 eyes were randomized and placed in two groups, 30 eyes underwent surgeries using the HYUIP technique (HYUIP group and 30 eyes underwent surgeries without the HYUIP technique (control. The three points evaluated during each surgery included 1 the occurrence of anterior chamber collapse during the pulling out of the I/A tip after inserting the intraocular lens, 2 the need for conventional hydration, and 3 watertight completion at the end stage of surgery.Results: The anterior chamber collapse and the need for conventional hydration were significantly smaller in the HYUIP group compared to the control group. Regarding the self-sealing completion, no significant difference was observed between the two groups.Conclusion: The HYUIP technique is an effective method for creating self-sealing wound. In addition, this technique helps to prevent anterior chamber collapse. Keywords: cataract surgery, hydration, irrigation and aspiration, phacoemulsification, wound, self-sealing 

  1. Gas hydrate saturation from acoustic impedance and resistivity logs in the shenhu area, south china sea

    Science.gov (United States)

    Wang, X.; Wu, S.; Lee, M.; Guo, Y.; Yang, S.; Liang, J.

    2011-01-01

    During the China's first gas hydrate drilling expedition -1 (GMGS-1), gas hydrate was discovered in layers ranging from 10 to 25 m above the base of gas hydrate stability zone in the Shenhu area, South China Sea. Water chemistry, electrical resistivity logs, and acoustic impedance were used to estimate gas hydrate saturations. Gas hydrate saturations estimated from the chloride concentrations range from 0 to 43% of the pore space. The higher gas hydrate saturations were present in the depth from 152 to 177 m at site SH7 and from 190 to 225 m at site SH2, respectively. Gas hydrate saturations estimated from the resistivity using Archie equation have similar trends to those from chloride concentrations. To examine the variability of gas hydrate saturations away from the wells, acoustic impedances calculated from the 3 D seismic data using constrained sparse inversion method were used. Well logs acquired at site SH7 were incorporated into the inversion by establishing a relation between the water-filled porosity, calculated using gas hydrate saturations estimated from the resistivity logs, and the acoustic impedance, calculated from density and velocity logs. Gas hydrate saturations estimated from acoustic impedance of seismic data are ???10-23% of the pore space and are comparable to those estimated from the well logs. The uncertainties in estimated gas hydrate saturations from seismic acoustic impedances were mainly from uncertainties associated with inverted acoustic impedance, the empirical relation between the water-filled porosities and acoustic impedances, and assumed background resistivity. ?? 2011 Elsevier Ltd.

  2. An effective medium inversion algorithm for gas hydrate quantification and its application to laboratory and borehole measurements of gas hydrate-bearing sediments

    Science.gov (United States)

    Chand, S.; Minshull, T.A.; Priest, J.A.; Best, A.I.; Clayton, C.R.I.; Waite, W.F.

    2006-01-01

    The presence of gas hydrate in marine sediments alters their physical properties. In some circumstances, gas hydrate may cement sediment grains together and dramatically increase the seismic P- and S-wave velocities of the composite medium. Hydrate may also form a load-bearing structure within the sediment microstructure, but with different seismic wave attenuation characteristics, changing the attenuation behaviour of the composite. Here we introduce an inversion algorithm based on effective medium modelling to infer hydrate saturations from velocity and attenuation measurements on hydrate-bearing sediments. The velocity increase is modelled as extra binding developed by gas hydrate that strengthens the sediment microstructure. The attenuation increase is modelled through a difference in fluid flow properties caused by different permeabilities in the sediment and hydrate microstructures. We relate velocity and attenuation increases in hydrate-bearing sediments to their hydrate content, using an effective medium inversion algorithm based on the self-consistent approximation (SCA), differential effective medium (DEM) theory, and Biot and squirt flow mechanisms of fluid flow. The inversion algorithm is able to convert observations in compressional and shear wave velocities and attenuations to hydrate saturation in the sediment pore space. We applied our algorithm to a data set from the Mallik 2L–38 well, Mackenzie delta, Canada, and to data from laboratory measurements on gas-rich and water-saturated sand samples. Predictions using our algorithm match the borehole data and water-saturated laboratory data if the proportion of hydrate contributing to the load-bearing structure increases with hydrate saturation. The predictions match the gas-rich laboratory data if that proportion decreases with hydrate saturation. We attribute this difference to differences in hydrate formation mechanisms between the two environments.

  3. Effect of bubble size and density on methane conversion to hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Leske, J.; Taylor, C.E.; Ladner, E.P.

    2007-03-01

    Research is underway at NETL to understand the physical properties of methane hydrates. One area of investigation is the storage of methane as methane hydrates. An economical and efficient means of storing methane in hydrates opens many commercial opportunities such as transport of stranded gas, off-peak storage of line gas, etc.We have observed during our investigations that the ability to convert methane to methane hydrate is enhanced by foaming of the methane–water solution using a surfactant. The density of the foam, along with the bubble size, is important in the conversion of methane to methane hydrate.

  4. Portland cement hydration in the presence of admixtures: black gram pulse and superplasticizer

    Directory of Open Access Journals (Sweden)

    Viveka Nand Dwivedi

    2008-12-01

    Full Text Available Effect of admixtures such as black gram pulse (BGP and sulfonated naphthalene based superplasticizer (SP on the hydration of Portland cement has been studied. The hydration characteristics of OPC in the presence of BGP and SP were studied with the help of non evaporable water content determinations, calorimetric method, Mössbauer spectroscopic and atomic force microscopic techniques. Results have shown that both BGP and SP get adsorbed at the surface of cement and its hydration products. The hydration of Portland cement is retarded in the presence of both the admixtures and nanosize hydration products are formed.

  5. Phase behavior of methane hydrate in silica sand

    International Nuclear Information System (INIS)

    Sun, Shi-Cai; Liu, Chang-Ling; Ye, Yu-Guang; Liu, Yu-Feng

    2014-01-01

    Highlights: • Hydrate p-T trace in coarse-grained sediment is consistent with that in bulk water. • Fine-grained sediment affects hydrate equilibrium for the depressed water activity. • Hydrate equilibrium in sediment is related to the pore size distribution. • The application of hydrate equilibrium in sediment depends on the actual condition. -- Abstract: Two kinds of silica sand powder with different particle size were used to investigate the phase behavior of methane hydrate bearing sediment. In coarse-grained silica sand, the measured temperature and pressure range was (281.1 to 284.2) K and (5.9 to 7.8) MPa, respectively. In fine-grained silica sand, the measured temperature and pressure range was (281.5 to 289.5) K and (7.3 to 16.0) MPa, respectively. The results show that the effect of coarse-grained silica sand on methane hydrate phase equilibrium can be ignored; however, the effect of fine-grained silica sand on methane hydrate phase equilibrium is significant, which is attributed to the depression of water activity caused by the hydrophilicity and negatively charged characteristic of silica particle as well as the pore capillary pressure. Besides, the analysis of experimental results using the Gibbs–Thomson equation shows that methane hydrate phase equilibrium is related to the pore size distribution of silica sand. Consequently, for the correct application of phase equilibrium data of hydrate bearing sediment, the geological condition and engineering requirement should be taken into consideration in gas production, resource evaluation, etc

  6. Basin-Wide Temperature Constraints On Gas Hydrate Stability In The Gulf Of Mexico

    Science.gov (United States)

    MacDonald, I. R.; Reagan, M. T.; Guinasso, N. L.; Garcia-Pineda, O. G.

    2012-12-01

    Gas hydrate deposits commonly occur at the seafloor-water interface on marine margins. They are especially prevalent in the Gulf of Mexico where they are associated with natural oil seeps. The stability of these deposits is potentially challenged by fluctuations in bottom water temperature, on an annual time-scale, and under the long-term influence of climate change. We mapped the locations of natural oil seeps where shallow gas hydrate deposits are known to occur across the entire Gulf of Mexico basin based on a comprehensive review of synthetic aperture radar (SAR) data (~200 images). We prepared a bottom water temperature map based on the archive of CTD casts from the Gulf (~6000 records). Comparing the distribution of gas hydrate deposits with predicted bottom water temperature, we find that a broad area of the upper slope lies above the theoretical stability horizon for structure 1 gas hydrate, while all sites where gas hydrate deposits occur are within the stability horizon for structure 2 gas hydrate. This is consistent with analytical results that structure 2 gas hydrates predominate on the upper slope (Klapp et al., 2010), where bottom water temperatures fluctuate over a 7 to 10 C range (approx. 600 m depth), while pure structure 1 hydrates are found at greater depths (approx. 3000 m). Where higher hydrocarbon gases are available, formation of structure 2 gas hydrate should significantly increase the resistance of shallow gas hydrate deposits to destabilizing effects variable or increasing bottom water temperature. Klapp, S.A., Bohrmann, G., Kuhs, W.F., Murshed, M.M., Pape, T., Klein, H., Techmer, K.S., Heeschen, K.U., and Abegg, F., 2010, Microstructures of structure I and II gas hydrates from the Gulf of Mexico: Marine and Petroleum Geology, v. 27, p. 116-125.Bottom temperature and pressure for Gulf of Mexico gas hydrate outcrops and stability horizons for sI and sII hydrate.

  7. 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.

  8. Replacement of CH4 in the hydrate by use of liquid CO2

    International Nuclear Information System (INIS)

    Ota, Masaki; Morohashi, Kenji; Abe, Yuki; Watanabe, Masaru; Smith, Richard Lee Jr.; Inomata, Hiroshi

    2005-01-01

    The dynamics of CH 4 replacement in the CH 4 hydrate with saturated liquid CO 2 at 273.2 K was measured with a high pressure optical cell. The results showed that CH 4 in the hydrate gradually moved to the liquid CO 2 phase while CO 2 in the liquid phase penetrated into the hydrate from the quantitative analysis. The decomposing process of the CH 4 hydrate during the replacement was analyzed with in situ Raman spectroscopy, which allowed us to distinguish the cage structure of the CH 4 hydrate and discuss the microscopic view of the replacement in the hydrate. It was found that the decomposition of the medium cage (M-cage) in the CH 4 hydrate proceeded faster than that of the small cage (S-cage). The observed rate difference could be related to the stability of the S-cage in the CH 4 hydrate or the re-formation tendency of CH 4 and water molecules in the S-cage after decomposing the hydrate structure, whereas the guest molecule exchange of CH 4 with CO 2 could occur in the M-cage. Based on the experimental data, we developed a kinetic model for calculation of the CH 4 remaining in the hydrate considering the decomposition rate difference between the M-cage and S-cage in the CH 4 hydrate. The results indicate that the driving force could be the fugacity difference between the fluid phase and the hydrate phase for the replacement process

  9. Preliminary Experimental Examination Of Controls On Methane Expulsion During Melting Of Natural Gas Hydrate Systems

    Science.gov (United States)

    Kneafsey, T. J.; Flemings, P. B.; Bryant, S. L.; You, K.; Polito, P. J.

    2013-12-01

    Global climate change will cause warming of the oceans and land. This will affect the occurrence, behavior, and location of subseafloor and subterranean methane hydrate deposits. We suggest that in many natural systems local salinity, elevated by hydrate formation or freshened by hydrate dissociation, may control gas transport through the hydrate stability zone. We are performing experiments and modeling the experiments to explore this behavior for different warming scenarios. Initially, we are exploring hydrate association/dissociation in saline systems with constant water mass. We compare experiments run with saline (3.5 wt. %) water vs. distilled water in a sand mixture at an initial water saturation of ~0.5. We increase the pore fluid (methane) pressure to 1050 psig. We then stepwise cool the sample into the hydrate stability field (~3 degrees C), allowing methane gas to enter as hydrate forms. We measure resistivity and the mass of methane consumed. We are currently running these experiments and we predict our results from equilibrium thermodynamics. In the fresh water case, the modeled final hydrate saturation is 63% and all water is consumed. In the saline case, the modeled final hydrate saturation is 47%, the salinity is 12.4 wt. %, and final water saturation is 13%. The fresh water system is water-limited: all the water is converted to hydrate. In the saline system, pore water salinity is elevated and salt is excluded from the hydrate structure during hydrate formation until the salinity drives the system to three phase equilibrium (liquid, gas, hydrate) and no further hydrate forms. In our laboratory we can impose temperature gradients within the column, and we will use this to investigate equilibrium conditions in large samples subjected to temperature gradients and changing temperature. In these tests, we will quantify the hydrate saturation and salinity over our meter-long sample using spatially distributed temperature sensors, spatially distributed

  10. Hydration numbers of trivalent lanthanide and actinide ions

    International Nuclear Information System (INIS)

    David, F.; Fourest, B.; Duplessis, J.

    1987-01-01

    Investigations on the structure of actinide aquo ions and determination of hydration numbers have to be studied, essentially, through radiochemical methods. They measured the transport numbers, diffusion coefficient D by the open end capillary method and ionic mobility u by electrophoresis. Both methods show a discontinuity in the transport number corresponding to the crystallographic radius of Eu 3+ or Bk 3+ ion. They deduced the volume of the actinide aquo ions, and the coordination number in the primary sphere. From calculations of the electrostriction phenomenon in the vicinity of central ion, they obtained effective volume of the water molecules and the dynamic hydration number corresponding to the second hydration sphere

  11. 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.

  12. 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.

  13. Infrared spectroscopy for monitoring gas hydrates in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, G.T.; Luzinova, Y.; Mizaikoff, B. [Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemistry and Biochemistry; Raichlin, Y.; Katzir, A. [Tel-Aviv Univ., Tel-Aviv (Israel). Shool of Physics and Astronomy

    2008-07-01

    This paper introduced the first principles for monitoring gas hydrate formation and dissociation in aqueous solution by evaluating state-responsive infrared (IR) absorption features of water with fiberoptic evanescent field spectroscopy. A first order linear functional relationship was also derived according to Lambert Beer's law in order to quantify the percentage gas hydrate within the volume of water probed via the evanescent field. In addition, spectroscopic studies evaluating seafloor sediments collected from a gas hydrate site in the Gulf of Mexico revealed minimal spectral interferences from sediment matrix components. As such, evanescent field sensing strategies were established as a promising perspective for monitoring the dynamics of gas hydrates in oceanic environments. 21 refs., 5 figs.

  14. Hysteresis of methane hydrate formation/decomposition at subsea geological conditions

    International Nuclear Information System (INIS)

    Klapproth, Alice; Piltz, Ross; Peterson, Vanessa K.; Kennedy, Shane J.; Kozielski, Karen A.; Hartley, Patrick G.

    2009-01-01

    Full text: Gas hydrates are a major risk when transporting oil and gas in offshore subsea pipelines. Under typical conditions in these pipelines (at high pressure and low temperature) the formation of gas hydrates is favourable. The hydrates form large solid plugs that can block pipelines and can even cause them to burst. This represents a major problem for the gas mining industry, which currently goes to extreme measures to reduce the risk of hydrate formation because there is no reliable experimental data on hydrate processes. The mechanisms of gas hydrate formation, growth and inhibition are poorly understood. A clear understanding of the fundamental processes will allow development of cost effective technologies to avoid production losses in gas pipelines. We are studying the nucleation of the methane hydrates by measuring the hysteresis of hydrate formation/decomposition by neutron diffraction. When a gas hydrate is decomposed (melted) the resulting water has a 'supposed memory effect' raising the probability of rapid hydrate reformation. This rapid reformation does not occur for pure water where nucleation can be delayed by several hours (induction time) due to metastability [1]. The memory effect can only be destroyed by extreme heating of the effected area. Possible causes of this effect include residual water structure, persistent hydrate crystal lites remaining in solution and remaining dissolved gas. We will compare the kinetics of formation and the stability region of hydrate formation of 'memory' water for comparison with pure water. This information has important implications for the oil and gas industry because it should provide a better understanding of the role of multiple dissociation and reformation of gas hydrates in plug formation.

  15. 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.)

  16. Propane hydrate nucleation: Experimental investigation and correlation

    DEFF Research Database (Denmark)

    Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas

    2008-01-01

    supersaturation region. The experiments showed that the gas dissolution rate rather than the induction time of propane hydrate is influenced by a change in agitation. This was especially valid at high stirring rates when the water surface was severely disturbed.Addition of polyvinylpyrrolidone (PVP......) to the aqueous phase was found to reduce the gas dissolution rate slightly. However the induction times were prolonged quite substantially upon addition of PVP.The induction time data were correlated using a newly developed induction time model based on crystallization theory also capable of taking into account...... the presence of additives. In most cases reasonable agreement between the data and the model could be obtained. The results revealed that especially the effective surface energy between propane hydrate and water is likely to change when the stirring rate varies from very high to low. The prolongation...

  17. Hydration benefits to courtship feeding in crickets

    OpenAIRE

    Ivy, T. M.; Johnson, J. C.; Sakaluk, S. K.

    1999-01-01

    The spermatophore transferred by male decorated crickets (Gryllodes sigillatus) at mating includes a large gelatinous spermatophylax that the female consumes after copulation. Although previous studies have shown that G. sigillatus females gain no nutritional benefits from consuming food gifts, there may be other benefits to their consumption. We examined potential hydration benefits to females by experimentally manipulating both the availability of water and the number of food gifts that fem...

  18. Methane hydrates. A possible energy source in the twenty-first century

    International Nuclear Information System (INIS)

    Sorassi, S.

    1998-01-01

    The morphological characteristics of particular crystal structures, to be found in nature both in arctic and Antarctic regions and under seas and oceans, and consisting of water and gas molecules, the so-called 'gas hydrates', are dealt with. Technical problems related to gas recovery (methane in particular) from hydrates, above all under sea level, mainly due to their reduced stability, are examined. On the ground of these considerations, various gas recovery methods from hydrate fields are described. An overall evaluation of methane availability as hydrates all over the world, as well as a comparison between extraction costs from hydrate and well as a comparison between extraction costs from hydrate and conventional fields, are made. Finally, short-term programmes on research and development of methane hydrate fields in some areas of the Earth are described [it

  19. 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.

  20. Microstructure of hydrated cement pastes as determined by SANS

    International Nuclear Information System (INIS)

    Sabine, T.; Bertram, W.; Aldridge, L.

    1999-01-01

    Full text: Technologists have known how to make concrete for over 2000 years but despite painstaking research no one has been able to show how and why concrete sets. Part of the problem is that the calcium silicate hydrate (the gel produced by hydrating cement) is amorphous and cannot be characterised by x-ray crystallographic techniques. Small angle neutron scattering on instrument V12a at BENSC was used to characterise the hydration reactions and show the growth of the calcium silicate hydrates during initial hydration and the substantial differences in the rate of growth and structure as different additives are used. SANS spectra were measured as a function of the hydration from three different types of cement paste: 1) Ordinary Portland Cement made with a water to cement ratio of about 0.4; 2) A blend of Ordinary Portland Cement(25%) and Ground Granulated Blast Furnace Slag (75%) with a water to cement ration of about 0.4; 3) A dense paste made from silica fume(24%), Ordinary Portland Cement (76%) at a water to powder ratio of 0.18. The differences in the spectra are interpreted in terms of differences between the microstructure of the pastes

  1. 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...

  2. 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)

  3. WatAA: Atlas of Protein Hydration. Exploring synergies between data mining and ab initio calculations.

    Science.gov (United States)

    Černý, Jiří; Schneider, Bohdan; Biedermannová, Lada

    2017-07-14

    Water molecules represent an integral part of proteins and a key determinant of protein structure, dynamics and function. WatAA is a newly developed, web-based atlas of amino-acid hydration in proteins. The atlas provides information about the ordered first hydration shell of the most populated amino-acid conformers in proteins. The data presented in the atlas are drawn from two sources: experimental data and ab initio quantum-mechanics calculations. The experimental part is based on a data-mining study of a large set of high-resolution protein crystal structures. The crystal-derived data include 3D maps of water distribution around amino-acids and probability of occurrence of each of the identified hydration sites. The quantum mechanics calculations validate and extend this primary description by optimizing the water position for each hydration site, by providing hydrogen atom positions and by quantifying the interaction energy that stabilizes the water molecule at the particular hydration site position. The calculations show that the majority of experimentally derived hydration sites are positioned near local energy minima for water, and the calculated interaction energies help to assess the preference of water for the individual hydration sites. We propose that the atlas can be used to validate water placement in electron density maps in crystallographic refinement, to locate water molecules mediating protein-ligand interactions in drug design, and to prepare and evaluate molecular dynamics simulations. WatAA: Atlas of Protein Hydration is freely available without login at .

  4. Study on molecular controlled mining system of methane hydrate; Methane hydrate no bunshi seigyo mining ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Kuriyagawa, M; Saito, T; Kobayashi, H; Karasawa, H; Kiyono, F; Nagaoki, R; Yamamoto, Y; Komai, T; Haneda, H; Takahashi, Y [National Institute for Resources and Environment, Tsukuba (Japan); Nada, H [Science and Technology Agency, Tokyo (Japan)

    1997-02-01

    Basic studies are conducted for the collection of methane from the methane hydrate that exists at levels deeper than 500m in the sea. The relationship between the hydrate generation mechanism and water cluster structure is examined by use of mass spectronomy. It is found that, among the stable liquid phase clusters, the (H2O)21H{sup +} cluster is the most stable. Stable hydrate clusters are in presence in quantities, and participate in the formation of hydrate crystal nuclei. For the elucidation of the nucleus formation mechanism, a kinetic simulation is conducted of molecules in the cohesion system consisting of water and methane molecules. Water molecules that array near methane molecules at the normal pressure is disarrayed under a higher pressure for rearray into a hydrate structure. Hydrate formation and breakdown in the three-phase equilibrium state of H2O, CH4, and CO2 at a low temperature and high pressure are tested, which discloses that supercooling is required for formation, that it is possible to extract CH4 first for replacement by guest molecule CO2 since CO2 is stabler than CH4 at a lower pressure or higher temperature, and that formation is easier to take place when the grain diameter is larger at the formation point since larger grain diameters result in a higher formation temperature. 3 figs.

  5. 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.

  6. 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.

  7. Simulating the effect of hydrate dissociation on wellhead stability during oil and gas development in deepwater

    Science.gov (United States)

    Li, Qingchao; Cheng, Yuanfang; Zhang, Huaiwen; Yan, Chuanliang; Liu, Yuwen

    2018-02-01

    It is well known that methane hydrate has been identified as an alternative resource due to its massive reserves and clean property. However, hydrate dissociation during oil and gas development (OGD) process in deep water can affect the stability of subsea equipment and formation. Currently, there is a serious lack of studies over quantitative assessment on the effects of hydrate dissociation on wellhead stability. In order to solve this problem, ABAQUS finite element software was used to develop a model and to evaluate the behavior of wellhead caused by hydrate dissociation. The factors that affect the wellhead stability include dissociation range, depth of hydrate formation and mechanical properties of dissociated hydrate region. Based on these, series of simulations were carried out to determine the wellhead displacement. The results revealed that, continuous dissociation of hydrate in homogeneous and isotropic formations can causes the non-linear increment in vertical displacement of wellhead. The displacement of wellhead showed good agreement with the settlement of overlying formations under the same conditions. In addition, the shallower and thicker hydrate formation can aggravate the influence of hydrate dissociation on the wellhead stability. Further, it was observed that with the declining elastic modulus and Poisson's ratio, the wellhead displacement increases. Hence, these findings not only confirm the effect of hydrate dissociation on the wellhead stability, but also lend support to the actions, such as cooling the drilling fluid, which can reduce the hydrate dissociation range and further make deepwater operations safer and more efficient.

  8. Unraveling halide hydration: A high dilution approach.

    Science.gov (United States)

    Migliorati, Valentina; Sessa, Francesco; Aquilanti, Giuliana; D'Angelo, Paola

    2014-07-28

    The hydration properties of halide aqua ions have been investigated combining classical Molecular Dynamics (MD) with Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. Three halide-water interaction potentials recently developed [M. M. Reif and P. H. Hünenberger, J. Chem. Phys. 134, 144104 (2011)], along with three plausible choices for the value of the absolute hydration free energy of the proton (ΔG [minus sign in circle symbol]hyd[H+]), have been checked for their capability to properly describe the structural properties of halide aqueous solutions, by comparing the MD structural results with EXAFS experimental data. A very good agreement between theory and experiment has been obtained with one parameter set, namely LE, thus strengthening preliminary evidences for a ΔG [minus sign in circle symbol]hyd[H] value of -1100 kJ mol(-1) [M. M. Reif and P. H. Hünenberger, J. Chem. Phys. 134, 144104 (2011)]. The Cl(-), Br(-), and I(-) ions have been found to form an unstructured and disordered first hydration shell in aqueous solution, with a broad distribution of instantaneous coordination numbers. Conversely, the F(-) ion shows more ordered and defined first solvation shell, with only two statistically relevant coordination geometries (six and sevenfold complexes). Our thorough investigation on the effect of halide ions on the microscopic structure of water highlights that the perturbation induced by the Cl(-), Br(-), and I(-) ions does not extend beyond the ion first hydration shell, and the structure of water in the F(-) second shell is also substantially unaffected by the ion.

  9. 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

  10. 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

  11. Major factors influencing the generation of natural gas hydrate in porous media

    Directory of Open Access Journals (Sweden)

    V.N. Khlebnikov

    2017-11-01

    Full Text Available Current researches related to natural gas hydrate mainly focus on its physical and chemical properties, as well as the approaches to the production (decomposition of hydrate. Physical modeling of the flow process in hydrate deposits is critical to the study on the exploitation or decomposition of hydrate. However, investigation of the dynamic hydrate process by virtue of porous media like sand-packed tubes which are widely used in petroleum production research is rarely reported in literature. In this paper, physical simulation of methane hydrate generation process was conducted using river sand-packed tubes in the core displacement apparatus. During the simulation, the influences of parameters such as reservoir temperature, methane pressure and reservoir model properties on the process of hydrate generation were investigated. The following results are revealed. First, the use of ice-melted water as the immobile water in the reservoir model can significantly enhance the rate of methane hydrate generation. Second, the process driving force in porous media (i.e., extents to which the experimental pressure or temperature deviating those corresponding to the hydrate phase equilibrium plays a key role in the generation of methane hydrate. Third, the induction period of methane hydrate generation almost does not change with temperature or pressure when the methane pressure is above 1.4 folds of the hydrate phase equilibrium pressure or the laboratory temperature is lower than the phase equilibrium temperature by 3 °C or more. Fourth, the parameters such as permeability, water saturation and wettability don't have much influence on the generation of methane hydrate.

  12. 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.

  13. Towards understanding the role of amines in the SO2 hydration and the contribution of the hydrated product to new particle formation in the Earth's atmosphere.

    Science.gov (United States)

    Lv, Guochun; Nadykto, Alexey B; Sun, Xiaomin; Zhang, Chenxi; Xu, Yisheng

    2018-08-01

    By theoretical calculations, the gas-phase SO 2 hydration reaction assisted by methylamine (MA) and dimethylamine (DMA) was investigated, and the potential contribution of the hydrated product to new particle formation (NPF) also was evaluated. The results show that the energy barrier for aliphatic amines (MA and DMA) assisted SO 2 hydration reaction is lower than the corresponding that of water and ammonia assisted SO 2 hydration. In these hydration reactions, nearly barrierless reaction (only a barrier of 0.1 kcal mol -1 ) can be found in the case of SO 2  + 2H 2 O + DMA. These lead us to conclude that the SO 2 hydration reaction assisted by MA and DMA is energetically facile. The temporal evolution for hydrated products (CH 3 NH 3 + -HSO 3 - -H 2 O or (CH 3 ) 2 NH 2 + -HSO 3 - -H 2 O) in molecular dynamics simulations indicates that these complexes can self-aggregate into bigger clusters and can absorb water and amine molecules, which means that these hydrated products formed by the hydration reaction may serve as a condensation nucleus to initiate the NPF. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Energy from gas hydrates - assessing the opportunities and challenges for Canada: report of the expert panel on gas hydrates

    International Nuclear Information System (INIS)

    2008-09-01

    Gas hydrates form when water and natural gas combine at low temperatures and high pressures in regions of permafrost and in marine subseafloor sediments. Estimates suggest that the total amount of natural gas bound in hydrate form may exceed all conventional gas resources, or even the amount of all combined hydrocarbon energy. Gas from gas hydrate could provide a potentially vast new source of energy to offset declining supplies of conventional natural gas in North America and to provide greater energy security for countries such as Japan and India that have limited domestic sources. However, complex issues would need to be addressed if gas hydrate were to become a large part of the energy future of Canada. Natural Resources Canada asked the Council of Canadian Academies to assemble a panel of experts to examine the challenges for an acceptable operational extraction of gas hydrates in Canada. This report presented an overview of relevant contextual background, including some basic science; the medium-term outlook for supply and demand in markets for natural gas; broad environmental issues related to gas hydrate in its natural state and as a fuel; and an overview of Canada's contribution to knowledge about gas hydrate in the context of ongoing international research activity. The report also presented current information on the subject and what would be required to delineate and quantify the resource. Techniques for extracting gas from gas hydrate were also outlined. The report also addressed safety issues related to gas hydrate dissociation during drilling operations or release into the atmosphere; the environmental issues associated with potential leakage of methane into the atmosphere and with the large volumes of water produced during gas hydrate dissociation; and jurisdictional and local community issues that would need to be resolved in order to proceed with the commercial exploitation of gas hydrate. It was concluded that there does not appear to be

  15. Investigation of Kinetic Hydrate Inhibition Using a High Pressure Micro Differential Scanning Calorimeter

    DEFF Research Database (Denmark)

    Daraboina, Nagu; Malmos, Christine; von Solms, Nicolas

    2013-01-01

    of hydrate growth. Additionally, hydrate formed in the presence of inhibitor decomposed at higher temperatures compared to pure water, indicating that while hydrate formation is initially inhibited; once hydrates form, they are more stable in the presence of inhibitor. Overall, this method proved a viable......Methane hydrate formation and decomposition were investigated in the presence of the kinetic inhibitor (Luvicap EG) and synergist (polyethylene oxide; PEO) using a high pressure micro-differential scanning calorimeter (HP-μDSC) with both temperature ramping and isothermal temperature programs....... These investigations were performed using small samples in four different capillary tubes in the calorimeter cell. When the isothermal method was employed, it was found that Luvicap EG significantly delays the hydrate nucleation time as compared to water. The results obtained from the ramping method demonstrated...

  16. Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming.

    Science.gov (United States)

    Wallmann, Klaus; Riedel, M; Hong, W L; Patton, H; Hubbard, A; Pape, T; Hsu, C W; Schmidt, C; Johnson, J E; Torres, M E; Andreassen, K; Berndt, C; Bohrmann, G

    2018-01-08

    Methane seepage from the upper continental slopes of Western Svalbard has previously been attributed to gas hydrate dissociation induced by anthropogenic warming of ambient bottom waters. Here we show that sediment cores drilled off Prins Karls Foreland contain freshwater from dissociating hydrates. However, our modeling indicates that the observed pore water freshening began around 8 ka BP when the rate of isostatic uplift outpaced eustatic sea-level rise. The resultant local shallowing and lowering of hydrostatic pressure forced gas hydrate dissociation and dissolved chloride depletions consistent with our geochemical analysis. Hence, we propose that hydrate dissociation was triggered by postglacial isostatic rebound rather than anthropogenic warming. Furthermore, we show that methane fluxes from dissociating hydrates were considerably smaller than present methane seepage rates implying that gas hydrates were not a major source of methane to the oceans, but rather acted as a dynamic seal, regulating methane release from deep geological reservoirs.

  17. 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.

  18. 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.

  19. Clinical study on orofacial photonic hydration using phototherapy and biomaterials

    Science.gov (United States)

    Lizarelli, Rosane F. Z.; Grandi, Natália D. P.; Florez, Fernando L. E.; Grecco, Clovis; Lopes, Luciana A.

    2015-06-01

    Skin hydration is important to prevent aging and dysfunction of orofacial system. Nowadays, it is known that cutaneous system is linked to muscle system, then every dentist need to treat healthy facial skin, as lips, keeping orofacial functions healthy. Thirty-two patients were treated using laser and led therapy single or associated to biomaterials (dermo-cosmetics) searching for the best protocol to promote skin hydration. Using a peace of equipment to measure electric impedance, percentage of water and oil from skin, before and after different treatments were analyzed. Statistic tests using 5% and 0.1% of significance were applied and results showed that light could improve hydration of epidermis layer of facial skin. Considering just light effect, using infrared laser followed by blue led system is more effective to hydration than just blue led system application. Considering dermo-cosmetic and light, the association between both presented the best result.

  20. 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.

  1. Intermolecular Hydrogen Transfer in Isobutane Hydrate

    Directory of Open Access Journals (Sweden)

    Takeshi Sugahara

    2012-05-01

    Full Text Available Electron spin resonance (ESR spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

  2. Predicting hydration energies for multivalent ions

    DEFF Research Database (Denmark)

    Andersson, Martin Peter; Stipp, Susan Louise Svane

    2014-01-01

    We have predicted the free energy of hydration for 40 monovalent and multivalent cations and anions using density functional theory and the implicit solvent model COnductor like Screening MOdel for Real Solvents (COSMO-RS) at the Becke-Perdew (BP)/Triple zeta valence with polarization functions...... (TZVP) level. Agreement with experimental data for monovalent and divalent ions is good and shows no significant systematic errors. Predictions are noticeably better than with standard COSMO. The agreement with experimental data for trivalent and tetravalent ions is slightly worse and shows systematic...... errors. Our results indicate that quantum chemical calculations combined with COSMO-RS solvent treatment is a reliable method for treating multivalent ions in solution, provided one hydration shell of explicit water molecules is included for metal cations. The accuracy is not high enough to allow...

  3. Phosphate vibrations as reporters of DNA hydration

    Science.gov (United States)

    Corcelli, Steven

    The asymmetric phosphate stretch vibrational frequency is extraordinarily sensitive to its local solvent environment. Using density functional theory calculations on the model compound dimethyl phosphate, the asymmetric phosphate stretch vibrational frequency was found to shift linearly with the magnitude of an electric field along the symmetry axis of the PO2 moiety (i.e. the asymmetric phosphate stretch is an excellent linear vibrational Stark effect probe). With this linear relationship established, asymmetric phosphate stretch vibrational frequencies were computed during the course of a molecular dynamics simulation of fully hydrated DNA. Moreover, contributions to shifts in the frequencies from subpopulations of water molecules (e.g. backbone, minor groove, major groove, etc.) were calculated to reveal how phosphate vibrations report the onset of DNA hydration in experiments that vary the relative humidity of non-condensing (dry) DNA samples.

  4. Gas hydrate occurrence in the Krishna-Godavari offshore basin off the east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Ramana, M.V.; Ramprasad, T.

    as the ecology of environment below the water and subsurface as well. Recent gas hydrate expeditions (Hydrate Ridge, Oregon Margin, Cascadian Margin, Gulf of Mexico, Arabian Sea, Bay of Bengal and Andaman Sea, South China Sea, East Sea) aboard JOIDES... boundaries, and associates with amplitude blanking above and below it. Further, the BSR also indicates a depth below which the hydrate destabilises. Some of the best known world major oilfields (for example the Gulf of Mexico, the Norwegian Sea, and along...

  5. 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

  6. Acoustical method of whole-body hydration status monitoring

    Science.gov (United States)

    Sarvazyan, A. P.; Tsyuryupa, S. N.; Calhoun, M.; Utter, A.

    2016-07-01

    An acoustical handheld hydration monitor (HM) for assessing the water balance of the human body was developed. Dehydration is a critical public health problem. Many elderly over age of 65 are particularly vulnerable as are infants and young children. Given that dehydration is both preventable and reversible, the need for an easy-to-perform method for the detection of water imbalance is of the utmost clinical importance. The HM is based on an experimental fact that ultrasound velocity in muscle is a linear function of water content and can be referenced to the hydration status of the body. Studies on the validity of HM for the assessment of whole-body hydration status were conducted in the Appalachian State University, USA, on healthy young adults and on elderly subjects residing at an assisted living facility. The HM was able to track changes in total body water during periods of acute dehydration and rehydration in athletes and day-to-day and diurnal variability of hydration in elderly. Results of human studies indicate that HM has a potential to become an efficient tool for detecting abnormal changes in the body hydration status.

  7. Fitness professionals' knowledge and perceptions on hydration and ...

    African Journals Online (AJOL)

    Fourty fitness professionals were asked to complete a questionnaire about their perspectives on hydration, thirst and fluid intake pattern. Water was the most preferred drink before (75.0%), during (72.5%) and after exercise (60.0%) as well as generally during the day (75.0%). Most participants rated plain tap water and plain ...

  8. Cation Hydration Constants by Proton NMR: A Physical Chemistry Experiment.

    Science.gov (United States)

    Smith, Robert L.; And Others

    1988-01-01

    Studies the polarization effect on water by cations and anions. Describes an experiment to illustrate the polarization effect of sodium, lithium, calcium, and strontium ions on the water molecule in the hydration spheres of the ions. Analysis is performed by proton NMR. (MVL)

  9. 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)

  10. 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.

  11. Effects of cyclopentane on CO2 hydrate formation and dissociation as a co-guest molecule for desalination

    International Nuclear Information System (INIS)

    Zheng, Jia-nan; Yang, Ming-jun; Liu, Yu; Wang, Da-yong; Song, Yong-chen

    2017-01-01

    Highlights: • CP decreases CO 2 hydrate phase equilibrium pressure by forming CO 2 -CP hydrates. • The increase of CP can’t decrease hydrates phase equilibrium pressure unlimitedly. • Higher CP concentration lowers CO 2 hydrate gas uptake. • The optimal CP molar ratio is 0.01 based on hydrate phase equilibrium and gas uptake. - Abstract: Cyclopentane (CP) is considered to be a potential co-guest molecule in carbon dioxide (CO 2 ) hydrate-based desalination. The experimental thermodynamic data of CO 2 -CP hydrates were measured for a salt solution, where CP was chosen as a hydrate promoter. Seven experimental cases (62 cycles) were studied with different molar ratios of CP/water (0, 0.0025, 0.005, 0.0075, 0.01, 0.02, and 0.03). Hydrate phase equilibrium data were generated using an isochoric method, and the hydrate saturations were calculated based on gas uptake. The results indicated that the increase in CP concentration significantly decreased the CO 2 hydrate equilibrium pressure to a certain limit; the hydrate saturation also decreased during this process. Also, it was determined that CP encouraged the formation of s-II double CO 2 -CP hydrates, which are different from s-I simple CO 2 hydrate. The CO 2 -CP guest provides a strengthened stability and moderate hydrate phase equilibrium conditions for hydrate-based desalination. The recommended optimal molar ratio of CP is 0.01 when the increase in equilibrium was more than 10 K, and the decrease in hydrate saturation was less than 2%.

  12. Animated molecular dynamics simulations of hydrated caesium-smectite interlayers

    Directory of Open Access Journals (Sweden)

    Sposito Garrison

    2002-09-01

    Full Text Available Computer animation of center of mass coordinates obtained from 800 ps molecular dynamics simulations of Cs-smectite hydrates (1/3 and 2/3 water monolayers provided information concerning the structure and dynamics of the interlayer region that could not be obtained through traditional simulation analysis methods. Cs+ formed inner sphere complexes with the mineral surface, and could be seen to jump from one attracting location near a layer charge site to the next, while water molecules were observed to migrate from the hydration shell of one ion to that of another. Neighboring ions maintained a partial hydration shell by sharing water molecules, such that a single water molecule hydrated two ions simultaneously for hundreds of picoseconds. Cs-montmorillonite hydrates featured the largest extent of this sharing interaction, because interlayer ions were able to inhabit positions near surface cavities as well as at their edges, close to oxygen triads. The greater positional freedom of Cs+ within the montmorillonite interlayer, a result of structural hydroxyl orientation and low tetrahedral charge, promoted the optimization of distances between cations and water molecules required for water sharing. Preference of Cs+ for locations near oxygen triads was observed within interlayer beidellite and hectorite. Water molecules also could be seen to interact directly with the mineral surface, entering its surface cavities to approach attracting charge sites and structural hydroxyls. With increasing water content, water molecules exhibited increased frequency and duration of both cavity habitation and water sharing interactions. Competition between Cs+ and water molecules for surface sites was evident. These important cooperative and competitive features of interlayer molecular behavior were uniquely revealed by animation of an otherwise highly complex simulation output.

  13. Animated molecular dynamics simulations of hydrated caesium-smectite interlayers

    Science.gov (United States)

    Sutton, Rebecca; Sposito, Garrison

    2002-01-01

    Computer animation of center of mass coordinates obtained from 800 ps molecular dynamics simulations of Cs-smectite hydrates (1/3 and 2/3 water monolayers) provided information concerning the structure and dynamics of the interlayer region that could not be obtained through traditional simulation analysis methods. Cs+ formed inner sphere complexes with the mineral surface, and could be seen to jump from one attracting location near a layer charge site to the next, while water molecules were observed to migrate from the hydration shell of one ion to that of another. Neighboring ions maintained a partial hydration shell by sharing water molecules, such that a single water molecule hydrated two ions simultaneously for hundreds of picoseconds. Cs-montmorillonite hydrates featured the largest extent of this sharing interaction, because interlayer ions were able to inhabit positions near surface cavities as well as at their edges, close to oxygen triads. The greater positional freedom of Cs+ within the montmorillonite interlayer, a result of structural hydroxyl orientation and low tetrahedral charge, promoted the optimization of distances between cations and water molecules required for water sharing. Preference of Cs+ for locations near oxygen triads was observed within interlayer beidellite and hectorite. Water molecules also could be seen to interact directly with the mineral surface, entering its surface cavities to approach attracting charge sites and structural hydroxyls. With increasing water content, water molecules exhibited increased frequency and duration of both cavity habitation and water sharing interactions. Competition between Cs+ and water molecules for surface sites was evident. These important cooperative and competitive features of interlayer molecular behavior were uniquely revealed by animation of an otherwise highly complex simulation output.

  14. 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)

  15. Vibrational spectra of halide-water dimers: Insights on ion hydration from full-dimensional quantum calculations on many-body potential energy surfaces

    Science.gov (United States)

    Bajaj, Pushp; Wang, Xiao-Gang; Carrington, Tucker; Paesani, Francesco

    2018-03-01

    Full-dimensional vibrational spectra are calculated for both X-(H2O) and X-(D2O) dimers (X = F, Cl, Br, I) at the quantum-mechanical level. The calculations are carried out on two sets of recently developed potential energy functions (PEFs), namely, Thole-type model energy (TTM-nrg) and many-body energy (MB-nrg), using the symmetry-adapted Lanczos algorithm with a product basis set including all six vibrational coordinates. Although both TTM-nrg and MB-nrg PEFs are derived from coupled-cluster single double triple-F12 data obtained in the complete basis set limit, they differ in how many-body effects are represented at short range. Specifically, while both models describe long-range interactions through the combination of two-body dispersion and many-body classical electrostatics, the relatively simple Born-Mayer functions employed in the TTM-nrg PEFs to represent short-range interactions are replaced in the MB-nrg PEFs by permutationally invariant polynomials to achieve chemical accuracy. For all dimers, the MB-nrg vibrational spectra are in close agreement with the available experimental data, correctly reproducing anharmonic and nuclear quantum effects. In contrast, the vibrational frequencies calculated with the TTM-nrg PEFs exhibit significant deviations from the experimental values. The comparison between the TTM-nrg and MB-nrg results thus reinforces the notion that an accurate representation of both short-range interactions associated with electron density overlap and long-range many-body electrostatic interactions is necessary for a correct description of hydration phenomena at the molecular level.

  16. Influence of Physical Activity and Ambient Temperature on Hydration: The European Hydration Research Study (EHRS

    Directory of Open Access Journals (Sweden)

    Ricardo Mora-Rodriguez

    2016-04-01

    Full Text Available This study explored the effects of physical activity (PA and ambient temperature on water turnover and hydration status. Five-hundred seventy three healthy men and women (aged 20–60 years from Spain, Greece and Germany self-reported PA, registered all food and beverage intake, and collected 24-h urine during seven consecutive days. Fasting blood samples were collected at the onset and end of the study. Food moisture was assessed using nutritional software to account for all water intake which was subtracted from daily urine volume to allow calculation of non-renal water loss (i.e., mostly sweating. Hydration status was assessed by urine and blood osmolality. A negative association was seen between ambient temperature and PA (r = −0.277; p < 0.001. Lower PA with high temperatures did not prevent increased non-renal water losses (i.e., sweating and elevated urine and blood osmolality (r = 0.218 to 0.163 all p < 0.001. When summer and winter data were combined PA was negatively associated with urine osmolality (r = −0.153; p = 0.001. Our data suggest that environmental heat acts to reduce voluntary PA but this is not sufficient to prevent moderate dehydration (increased osmolality. On the other hand, increased PA is associated with improved hydration status (i.e., lower urine and blood osmolality.

  17. 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

    Interest in gas hydrates has increased in recent years due to the discovery of large deposits under the ocean floor and in permafrost regions. Natural gas hydrates, including methane, is expected to become a new energy source and a medium for energy storage and transportation. Gas hydrates consist of an open network of water molecules that are hydrogen-bonded in a similar manner to ice. Gas molecules are interstitially engaged under high pressures and low temperatures. Although the dissociation temperature of methane hydrate under atmospheric pressure is about 193 K, studies have shown that methane hydrate can be stored at atmospheric pressure and 267 K for 2 years. Because of this phenomenon, known as self-preservation, transportation and storage of methane hydrate can occur at temperature conditions milder than those for liquefied methane gas at atmospheric pressure. This study examined the surface changes of methane and ethane hydrates during dissociation using an optical microscope and confocal scanning microscope (CSM). This paper reported on the results when the atmospheric gas pressure was decreased. Ice sheets formed on the surfaces of methane and ethane gas hydrates due to depressurizing dissociation of methane and ethane hydrates when the methane and ethane gas pressures were decreased at designated temperatures. The dissociation of methane gas hydrate below below 237 K resulted in the generation of small ice particles on the hydrate surface. A transparent ice sheet formed on the hydrate surface above 242 K. The thickness of the ice sheet on the methane hydrate surface showed the maximum of ca. 30 {mu}m at 253 K. In the case of ethane hydrates, ice particles and ice sheets formed below 262 and 267 respectively. Since the ice particles and ice sheets were formed by water molecules generated during the gas hydrate dissociation, the mechanism of ice sheet formation depends on the dissociation rate of hydrate, ice particle sintering rate, and water molecule

  18. Shallow methane hydrate system controls ongoing, downslope sediment transport in a low-velocity active submarine landslide complex, Hikurangi Margin, New Zealand

    Science.gov (United States)

    Mountjoy, Joshu J.; Pecher, Ingo; Henrys, Stuart; Crutchley, Gareth; Barnes, Philip M.; Plaza-Faverola, Andreia

    2014-11-01

    Morphological and seismic data from a submarine landslide complex east of New Zealand indicate flow-like deformation within gas hydrate-bearing sediment. This "creeping" deformation occurs immediately downslope of where the base of gas hydrate stability reaches the seafloor, suggesting involvement of gas hydrates. We present evidence that, contrary to conventional views, gas hydrates can directly destabilize the seafloor. Three mechanisms could explain how the shallow gas hydrate system could control these landslides. (1) Gas hydrate dissociation could result in excess pore pressure within the upper reaches of the landslide. (2) Overpressure below low-permeability gas hydrate-bearing sediments could cause hydrofracturing in the gas hydrate zone valving excess pore pressure into the landslide body. (3) Gas hydrate-bearing sediment could exhibit time-dependent plastic deformation enabling glacial-style deformation. We favor the final hypothesis that the landslides are actually creeping seafloor glaciers. The viability of rheologically controlled deformation of a hydrate sediment mix is supported by recent laboratory observations of time-dependent deformation behavior of gas hydrate-bearing sands. The controlling hydrate is likely to be strongly dependent on formation controls and intersediment hydrate morphology. Our results constitute a paradigm shift for evaluating the effect of gas hydrates on seafloor strength which, given the widespread occurrence of gas hydrates in the submarine environment, may require a reevaluation of slope stability following future climate-forced variation in bottom-water temperature.

  19. The structural response of the cornea to changes in stromal hydration.

    Science.gov (United States)

    Hayes, Sally; White, Tomas; Boote, Craig; Kamma-Lorger, Christina S; Bell, James; Sorenson, Thomas; Terrill, Nick; Shebanova, Olga; Meek, Keith M

    2017-06-01

    The primary aim of this study was to quantify the relationship between corneal structure and hydration in humans and pigs. X-ray scattering data were collected from human and porcine corneas equilibrated with polyethylene glycol (PEG) to varying levels of hydration, to obtain measurements of collagen fibril diameter, interfibrillar spacing (IFS) and intermolecular spacing. Both species showed a strong positive linear correlation between hydration and IFS 2 and a nonlinear, bi-phasic relationship between hydration and fibril diameter, whereby fibril diameter increased up to approximately physiological hydration, H = 3.0, with little change thereafter. Above H = 3.0, porcine corneas exhibited a larger fibril diameter than human corneas ( p < 0.001). Intermolecular spacing also varied with hydration in a bi-phasic manner but reached a maximum value at a lower hydration ( H = 1.5) than fibril diameter. Human corneas displayed a higher intermolecular spacing than porcine corneas at all hydrations ( p < 0.0001). Human and porcine corneas required a similar PEG concentration to reach physiological hydration, suggesting that the total fixed charge that gives rise to the swelling pressure is the same. The difference in their structural responses to hydration can be explained by variations in molecular cross-linking and intra/interfibrillar water partitioning. © 2017 The Authors.

  20. Gas Hydrate-Sediment Morphologies Revealed by Pressure Core Analysis

    Science.gov (United States)

    Holland, M.; Schultheiss, P.; Roberts, J.; Druce, M.

    2006-12-01

    Analysis of HYACINTH pressure cores collected on IODP Expedition 311 and NGHP Expedition 1 showed gas hydrate layers, lenses, and veins contained in fine-grained sediments as well as gas hydrate contained in coarse-grained layers. Pressure cores were recovered from sediments on the Cascadia Margin off the North American West Coast and in the Krishna-Godavari Basin in the Western Bay of Bengal in water depths of 800- 1400 meters. Recovered cores were transferred to laboratory chambers without loss of pressure and nondestructive measurements were made at in situ pressures and controlled temperatures. Gamma density, P-wave velocity, and X-ray images showed evidence of grain-displacing and pore-filling gas hydrate in the cores. Data highlights include X-ray images of fine-grained sediment cores showing wispy subvertical veins of gas hydrate and P-wave velocity excursions corresponding to grain-displacing layers and pore-filling layers of gas hydrate. Most cores were subjected to controlled depressurization experiments, where expelled gas was collected, analyzed for composition, and used to calculate gas hydrate saturation within the core. Selected cores were stored under pressure for postcruise analysis and subsampling.

  1. Gas hydrates: entrance to a methane age or climate threat?

    International Nuclear Information System (INIS)

    Krey, Volker; Nakicenovic, Nebojsa; Grubler, Arnulf; O'Neill, Brian; Riahi, Keywan; Canadell, Josep G; Abe, Yuichi; Andruleit, Harald; Archer, David; Hamilton, Neil T M; Johnson, Arthur; Kostov, Veselin; Lamarque, Jean-Francois; Langhorne, Nicholas; Nisbet, Euan G; Riedel, Michael; Wang Weihua; Yakushev, Vladimir

    2009-01-01

    Methane hydrates, ice-like compounds in which methane is held in crystalline cages formed by water molecules, are widespread in areas of permafrost such as the Arctic and in sediments on the continental margins. They are a potentially vast fossil fuel energy source but, at the same time, could be destabilized by changing pressure-temperature conditions due to climate change, potentially leading to strong positive carbon-climate feedbacks. To enhance our understanding of both the vulnerability of and the opportunity provided by methane hydrates, it is necessary (i) to conduct basic research that improves the highly uncertain estimates of hydrate occurrences and their response to changing environmental conditions, and (ii) to integrate the agendas of energy security and climate change which can provide an opportunity for methane hydrates-in particular if combined with carbon capture and storage-to be used as a 'bridge fuel' between carbon-intensive fossil energies and zero-emission energies. Taken one step further, exploitation of dissociating methane hydrates could even mitigate against escape of methane to the atmosphere. Despite these opportunities, so far, methane hydrates have been largely absent from energy and climate discussions, including global hydrocarbon assessments and the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.

  2. 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.

  3. The use of hydrated lime in acid mine drainage treatment

    Science.gov (United States)

    Othman, Anuar; Sulaiman, Azli; Sulaiman, Shamsul Kamal

    2017-05-01

    Hydrated lime also known as calcium hydroxide with chemical formula Ca(OH)2 was used in this study as neutralization agent in acid mine drainage (AMD) treatment. Hydrated lime that is used to treat pool water samples from tin tailings located in Pengkalan Hulu, Perak was obtained from Simpang Pulai, Perak. The pH of water sample was around 2.6 to 2.8. Ten different variables of hydrated lime weights were used to treat 1 L of water sample. The weights of hydrated lime used were 0.2 g, 0.4 g, 0.6 g, 0.8 g, 1.0 g, 1.2 g, 1.4 g, 1.6 g, 1.8 g and 2.0 g. Time interval used was every 5 minutes up to minutes 30. Jar test method was used in this study. The maximum pH value of 5.93 ± 0.03 most approaches standard A and had complied standard B have been obtained using 2.0 g hydrated lime in 30-minute time interval. The concentration of arsenic, cadmium and chromium had decreased but only cadmium concentration did not comply with Standards A and B.

  4. Polymorphism in Br2 clathrate hydrates.

    Science.gov (United States)

    Goldschleger, I U; Kerenskaya, G; Janda, K C; Apkarian, V A

    2008-02-07

    The structure and composition of bromine clathrate hydrate has been controversial for more than 170 years due to the large variation of its observed stoichiometries. Several different crystal structures were proposed before 1997 when Udachin et al. (Udachin, K. A.; Enright, G. D.; Ratcliffe, C. I.; Ripmeester, J. A. J. Am. Chem. Soc. 1997, 119, 11481) concluded that Br2 forms only the tetragonal structure (TS-I). We show polymorphism in Br2 clathrate hydrates by identifying two distinct crystal structures through optical microscopy and resonant Raman spectroscopy on single crystals. After growing TS-I crystals from a liquid bromine-water solution, upon dropping the temperature slightly below -7 degrees C, new crystals of cubic morphology form. The new crystals, which have a limited thermal stability range, are assigned to the CS-II structure. The two structures are clearly distinguished by the resonant Raman spectra of the enclathrated Br2, which show long overtone progressions and allow the extraction of accurate vibrational parameters: omega(e) = 321.2 +/- 0.1 cm(-1) and omega(e)x(e) = 0.82 +/- 0.05 cm(-1) in TS-I and omega(e) = 317.5 +/- 0.1 cm(-1) and omega(e)x(e) = 0.70 +/- 0.1 cm(-1) in CS-II. On the basis of structural analysis, the discovery of the CS-II crystals implies stability of a large class of bromine hydrate structures and, therefore, polymorphism.

  5. Electronic structure calculations of calcium silicate hydrates

    International Nuclear Information System (INIS)

    Sterne, P.A.; Meike, A.

    1995-11-01

    Many phases in the calcium-silicate-hydrate system can develop in cement exposed over long periods of time to temperatures above 25 C. As a consequence, chemical reactions involving these phases can affect the relative humidity and water chemistry of a radioactive waste repository that contains significant amounts of cement. In order to predict and simulate these chemical reactions, the authors are developing an internally consistent database of crystalline Ca-Si-hydrate structures. The results of first principles electronic structure calculations on two such phases, wollastonite (CaSiO 3 ) and xonotlite (Ca 6 Si 6 O 17 (OH) 2 ), are reported here. The calculated ground state properties are in very good agreement with experiment, providing equilibrium lattice parameters within about 1--1.4% of the experimentally reported values. The roles of the different types of oxygen atoms, which are fundamental to understanding the energetics of crystalline Ca-Si-hydrates are briefly discussed in terms of their electronic state densities. The good agreement with experiment for the lattice parameters and the consistency of the electronic density of states features for the two structures demonstrate the applicability of these electronic structure methods in calculating the fundamental properties of these phases

  6. TOUGH+Hydrate v1.0 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George; Moridis, George J.; Kowalsky, Michael B.; Pruess, Karsten

    2008-03-01

    TOUGH+HYDRATE v1.0 is a new code for the simulation of the behavior of hydrate-bearing geologic systems. By solving the coupled equations of mass and heat balance, TOUGH+HYDRATE can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH{sub 4}-hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy's law is valid. TOUGH+HYDRATE v1.0 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH{sub 4}, hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dissociation or formation, phase changes and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects. TOUGH+HYDRATE is the first member of TOUGH+, the successor to the TOUGH2 [Pruess et al., 1991] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95, and can be run on any computational platform (workstation, PC, Macintosh) for which such compilers are available.

  7. Modelling of tetrahydrofuran promoted gas hydrate systems for carbon dioxide capture processes

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

    2014-01-01

    A thermodynamic study of a novel gas hydrate based CO2 capture process is presented.•Model predicts this process unsuitable for CO2 capture from power station flue gases. A thermodynamic modelling study of both fluid phase behaviour and hydrate phase behaviour is presented for the quaternary system...... of water, tetrahydrofuran, carbon dioxide and nitrogen. The applied model incorporates the Cubic-Plus-Association (CPA) equation of state for the fluid phase description and the van der Waals-Platteeuw hydrate model for the solid (hydrate) phase. Six binary pairs are studied for their fluid phase behaviour...... accurate descriptions of both fluid- and hydrate phase equilibria in the studied system and its subsystems. The developed model is applied to simulate two simplified, gas hydrate-based processes for post-combustion carbon dioxide capture from power station flue gases. The first process, an unpromoted...

  8. Nonequilibrium Thermodynamics of Hydrate Growth on a Gas-Liquid Interface

    Science.gov (United States)

    Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

    2018-04-01

    We develop a continuum-scale phase-field model to study gas-liquid-hydrate systems far from thermodynamic equilibrium. We design a Gibbs free energy functional for methane-water mixtures that recovers the isobaric temperature-composition phase diagram under thermodynamic equilibrium conditions. The proposed free energy is incorporated into a phase-field model to study the dynamics of hydrate formation on a gas-liquid interface. We elucidate the role of initial aqueous concentration in determining the direction of hydrate growth at the interface, in agreement with experimental observations. Our model also reveals two stages of hydrate growth at an interface—controlled by a crossover in how methane is supplied from the gas and liquid phases—which could explain the persistence of gas conduits in hydrate-bearing sediments and other nonequilibrium phenomena commonly observed in natural methane hydrate systems.

  9. Hydration kinetics modeling of Portland cement considering the effects of curing temperature and applied pressure

    International Nuclear Information System (INIS)

    Lin Feng; Meyer, Christian

    2009-01-01

    A hydration kinetics model for Portland cement is formulated based on thermodynamics of multiphase porous media. The mechanism of cement hydration is discussed based on literature review. The model is then developed considering the effects of chemical composition and fineness of cement, water-cement ratio, curing temperature and applied pressure. The ultimate degree of hydration of Portland cement is also analyzed and a corresponding formula is established. The model is calibrated against the experimental data for eight different Portland cements. Simple relations between the model parameters and cement composition are obtained and used to predict hydration kinetics. The model is used to reproduce experimental results on hydration kinetics, adiabatic temperature rise, and chemical shrinkage of different cement pastes. The comparisons between the model reproductions and the different experimental results demonstrate the applicability of the proposed model, especially for cement hydration at elevated temperature and high pressure.

  10. Numerical simulation studies of gas production scenarios from hydrate accumulations at the Mallik Site, McKenzie Delta, Canada

    International Nuclear Information System (INIS)

    Moridis, George J.; Collett, Timothy S.; Dallimore, Scott R.; Satoh, Tohru; Hancock, Stephen; Weatherill, Brian

    2002-01-01

    The Mallik site represents an onshore permafrost-associated gas hydrate accumulation in the Mackenzie Delta, Northwest Territories, Canada. An 1150 m deep gas hydrate research well was drilled at the site in 1998. The objective of this study is the analysis of various gas production scenarios from several gas-hydrate-bearing zones at the Mallik site. The TOUGH2 general-purpose simulator with the EOSHYDR2 module were used for the analysis. EOSHYDR2 is designed to model the non-isothermal CH(sub 4) (methane) release, phase behavior and flow under conditions typical of methane-hydrate deposits by solving the coupled equations of mass and heat balance, and can describe any combination of gas hydrate dissociation mechanisms. Numerical simulations indicated that significant gas hydrate production at the Mallik site was possible by drawing down the pressure on a thin free-gas zone at the base of the hydrate stability field. Gas hydrate zones with underlying aquifers yielded significant gas production entirely from dissociated gas hydrate, but large amounts of produced water. Lithologically isolated gas-hydrate-bearing reservoirs with no underlying free gas or water zones, and gas-hydrate saturations of at least 50% were also studied. In these cases, it was assumed that thermal stimulation by circulating hot water in the well was the method used to induce dissociation. Sensitivity studies indicated that the methane release from the hydrate accumulations increases with gas-hydrate saturation, the initial formation temperature, the temperature of the circulating water in the well, and the formation thermal conductivity. Methane production appears to be less sensitive to the rock and hydrate specific heat and permeability of the formation

  11. Non-invasive measurement of corneal hydration.

    Science.gov (United States)

    March, W F; Bauer, N J

    2001-01-01

    To investigate the feasibility of a confocal Raman spectroscopic technique for the noncontact assessment of corneal hydration in vivo in two legally blind subjects. A laser beam (632.8 nm; 15 mJ) was maintained on the cornea using a microscope objective lens (25x magnification, NA=0.5, f=10 mm) both for focusing the incident light as well as collecting the Raman backscattered light, in a 180 degrees backscatter configuration. An optical fiber, acting as the confocal pinhole for elimination of light from out-of-focus places, was coupled to a spectrometer that dispersed the collected light onto a sensitive array-detector for rapid spectral data acquisition over a range from 2,890 to 3,590 cm(-1). Raman spectra were recorded from the anterior 100 to 150 microm of the cornea over a period of time before and after topical application of a mild dehydrating solution. The ratio between the amplitudes of the signals at 3,400 cm(-1) (OH-vibrational mode of water) and 2,940 cm(-1) (CH-vibrational mode of proteins) was used as a measure of corneal hydration. High signal-to-noise ratio (SNR 25) Raman spectra were obtained from the human corneas using 15 mJ of laser light energy. Qualitative changes in the hydration of the anterior-most part of the corneas could be observed as a result of the dehydrating agent. Confocal Raman spectroscopy could potentially be applied clinically as a noncontact tool for the assessment of corneal hydration in vivo.

  12. Thermodynamic promotion of carbon dioxide-clathrate hydrate formation by tetrahydrofuran, cyclopentane and their mixtures

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

    2013-01-01

    Gas clathrate hydrate dissociation pressures are reported for mixtures of carbon dioxide, water and thermodynamic promoters forming structure II hydrates.Hydrate (H)-aqueous liquid (Lw)-vapour (V) equilibrium pressures for the ternary system composed of water, tetrahydrofuran (THF), and carbon....... It is shown that upon adding THF to the pure aqueous phase to form a 4mass percent solution, the equilibrium pressure of the formed hydrates may be lowered compared to the ternary system of water, cyclopentane and carbon dioxide. © 2013 Elsevier Ltd....... dioxide (CO2), with 5.0mole percent THF in the initial aqueous phase, are presented in the temperature range from 283.3K to 285.2K. At 283.3K, the three-phase equilibrium pressure is determined to be 0.61MPa (absolute pressure).Four-phase hydrate (H)-aqueous liquid (Lw)-organic liquid (La)-vapour (V...

  13. Investigation on the effect of THF on Nitrogen Hydrate formation under isobaric condition

    Science.gov (United States)

    Jamil, N.; Husin, H.; Aman, Z.; Hassan, Z.

    2018-03-01

    In this paper, we studied nitrogen (N2) hydrate formation in the presence of tetrahydrofuran (THF) under 3 different conditions; different concentration of THF (0, 3 and 30 %(v/v), different temperature setting (room temperature and induced temperature) and different water content (15, 35 and 55 mL) in an isobaric condition. We found that in the presence of THF which acting as an enhancer, hydrate formation kinetic is highly influenced by these parameters. We observed a striking contrast in hydrate formation behaviour observed at room temperature (RT) and induced temperature (IT) with and without the presence of THF under similar operating conditions. At the presence of 30 %(v/v) of THF in 15 mL water, it can be seen that, hydrate tend to form faster than other samples. Visual observation of N2hydrates are also conducted at 30 %(v/v) of THF in 15 mL water.

  14. Cryogenic-SEM investigation of CO{sub 2} hydrate morphologies

    Energy Technology Data Exchange (ETDEWEB)

    Camps, A.P.; Milodowski, A.; Rochelle, C.; Williams, J.F.; Jackson, P. D. [British Geological Survey, Keyworth, Nottinghamshire (United Kingdom); Camps, A.P; Lovell, M.; Williams, J.F. [Leicester Univ., Leicester (United Kingdom). Dept. of Geology

    2008-07-01

    Gas hydrates occur naturally around the world in the shallow-marine geosphere, and are seen as a drilling hazard in the petroleum industry due to their role in the carbon cycle, and their possible contribution in past and present climate change. Hydrates are ice-like structures composed of cages of water molecules containing one or more guest molecules, such as methane and carbon dioxide (CO{sub 2}). CO{sub 2} hydrates also occur naturally on earth and are being investigated for their potential to store large volumes of CO{sub 2} to reduce atmospheric emissions of greenhouse gases as a climate change mitigation strategy. However, the mineralogy and formation processes of hydrates are relatively poorly understood. Different imaging techniques have been utilized to study gas hydrates, such as nuclear magnetic resonance, magnetic resonance imaging, and x-ray computed tomography. Scanning Electron Microscopy (SEM) at cryogenic temperatures is another technique to study hydrates, and has been used successfully for investigation of methane and CO{sub 2} hydrates. This paper presented a study that investigated CO{sub 2} hydrates formed in laboratories, using a cryogenic-SEM. The paper presented the study methods and observations, including euhedral crystalline carbon dioxide hydrate; acicular carbon dioxide hydrate; granoblastic carbon dioxide hydrate; and gas rich carbon dioxide hydrate. It was concluded that the investigation produced various different hydrate morphologies resulting from different formation conditions. Morphologies ranged from well-defined euhedral crystals to acicular needles, and more complex, intricate forms. 22 refs., 6 figs., 1 appendix.

  15. Adsorption Mechanism of Inhibitor and Guest Molecules on the Surface of Gas Hydrates.

    Science.gov (United States)

    Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki

    2015-09-23

    The adsorption of guest and kinetic inhibitor molecules on the surface of methane hydrate is investigated by using molecular dynamics simulations. We calculate the free energy profile for transferring a solute molecule from bulk water to the hydrate surface for various molecules. Spherical solutes with a diameter of ∼0.5 nm are significantly stabilized at the hydrate surface, whereas smaller and larger solutes exhibit lower adsorption affinity than the solutes of intermediate size. The range of the attractive force is subnanoscale, implying that this force has no effect on the macroscopic mass transfer of guest molecules in crystal growth processes of gas hydrates. We also examine the adsorption mechanism of a kinetic hydrate inhibitor. It is found that a monomer of the kinetic hydrate inhibitor is strongly adsorbed on the hydrate surface. However, the hydrogen bonding between the amide group of the inhibitor and water molecules on the hydrate surface, which was believed to be the driving force for the adsorption, makes no contribution to the adsorption affinity. The preferential adsorption of both the kinetic inhibitor and the spherical molecules to the surface is mainly due to the entropic stabilization arising from the presence of cavities at the hydrate surface. The dependence of surface affinity on the size of adsorbed molecules is also explained by this mechanism.

  16. Thermal properties of methane hydrate by experiment and modeling and impacts upon technology

    Energy Technology Data Exchange (ETDEWEB)

    Warzinski, R.P.; Gamwo, I.K.; Rosenbaum, E.J. [United States Dept. of Energy, Pittsburgh, PA (United States). National Energy Technology Laboratory; Myshakin, E.M. [NETL Support Contractor, South Park, PA (United States); Jiang, H.; Jordan, K.D. [Pittsburgh Univ., Pittsburgh, PA (United States). Dept. of Chemistry; English, N.J. [Dublin University College, Dublin (Ireland). Conway Inst. of Biomolecular and Biomedical Research, Centre for Synthesis and Chemical Biology; Shaw, D.W. [Geneva College, Beaver Falls, PA (United States). Dept. of Engineering

    2008-07-01

    The current hydrate research at the National Energy Technology Laboratory (NETL) involves both experimental and theoretical work on developing models and methods for predicting the behaviour of gas hydrates in their natural environment under production of climate change scenarios. The modeling efforts include both fundamental and reservoir scale simulations and economic modeling. The thermal properties of methane hydrate are important for hydrate production, seafloor stability and climate change scenarios. A new experimental technique and advanced molecular dynamics simulation (MDS) have determined the thermal properties of pure methane hydrate under conditions similar to naturally occurring hydrate-bearing sediments. The thermal conductivity and thermal diffusivity values of low-porosity methane hydrate formed in the laboratory were measured using an innovative single-sided, Transient Plane Source (TPS) technique. The results were in good agreement with results from an equilibrium MDS method using in-plane polarization of the water molecules. MDS was also performed using a non-equilibrium model with a fully polarizable force field for water. The Tough+Hydrate reservoir simulator was also used to evaluate the impact of thermal conductivity on gas production from a hydrate-bearing reservoir. 42 refs., 1 tab., 5 figs.

  17. Experimental determination of CCl4 hydrate phase equlibria up to high pressures

    NARCIS (Netherlands)

    Shariati - Sarabi, A.; Lameris, G.H.; Peters, C.J.

    2015-01-01

    A number of hydrate phase boundaries of the binary system of tetrachloromethane (CCl4) + water were measured experimentally at several temperatures and from low pressures up to 89.25 MPa. These hydrate phase boundaries included hydrate–ice–vapor, hydrate–liquid CCl4–vapor, hydrate–water–vapor,

  18. Structure of the ordered hydration of amino acids in proteins: analysis of crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Biedermannová, Lada, E-mail: lada.biedermannova@ibt.cas.cz; Schneider, Bohdan [Institute of Biotechnology CAS, Videnska 1083, 142 20 Prague (Czech Republic)

    2015-10-27

    The hydration of protein crystal structures was studied at the level of individual amino acids. The dependence of the number of water molecules and their preferred spatial localization on various parameters, such as solvent accessibility, secondary structure and side-chain conformation, was determined. Crystallography provides unique information about the arrangement of water molecules near protein surfaces. Using a nonredundant set of 2818 protein crystal structures with a resolution of better than 1.8 Å, the extent and structure of the hydration shell of all 20 standard amino-acid residues were analyzed as function of the residue conformation, secondary structure and solvent accessibility. The results show how hydration depends on the amino-acid conformation and the environment in which it occurs. After conformational clustering of individual residues, the density distribution of water molecules was compiled and the preferred hydration sites were determined as maxima in the pseudo-electron-density representation of water distributions. Many hydration sites interact with both main-chain and side-chain amino-acid atoms, and several occurrences of hydration sites with less canonical contacts, such as carbon–donor hydrogen bonds, OH–π interactions and off-plane interactions with aromatic heteroatoms, are also reported. Information about the location and relative importance of the empirically determined preferred hydration sites in proteins has applications in improving the current methods of hydration-site prediction in molecular replacement, ab initio protein structure prediction and the set-up of molecular-dynamics simulations.

  19. Phase equilibria and thermodynamic modeling of ethane and propane hydrates in porous silica gels.

    Science.gov (United States)

    Seo, Yongwon; Lee, Seungmin; Cha, Inuk; Lee, Ju Dong; Lee, Huen

    2009-04-23

    In the present study, we examined the active role of porous silica gels when used as natural gas storage and transportation media. We adopted the dispersed water in silica gel pores to substantially enhance active surface for contacting and encaging gas molecules. We measured the three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria of C(2)H(6) and C(3)H(8) hydrates in 6.0, 15.0, 30.0, and 100.0 nm silica gel pores to investigate the effect of geometrical constraints on gas hydrate phase equilibria. At specified temperatures, the hydrate stability region is shifted to a higher pressure region depending on pore size when compared with those of bulk hydrates. Through application of the Gibbs-Thomson relationship to the experimental data, we determined the values for the C(2)H(6) hydrate-water and C(3)H(8) hydrate-water interfacial tensions to be 39 +/- 2 and 45 +/- 1 mJ/m(2), respectively. By using these values, the calculation values were in good agreement with the experimental ones. The overall results given in this study could also be quite useful in various fields, such as exploitation of natural gas hydrate in marine sediments and sequestration of carbon dioxide into the deep ocean.

  20. Dehydration/hydration of granular beds for thermal storage applications: a combined NMR and temperature study

    NARCIS (Netherlands)

    Donkers, P.A.J.; Pel, L.; Adan, O.C.G.

    For heat/cold storage systems a granular bed of salt hydrates is studied during dehydration/hydration. The water density in these beds are measured with help of NMR. Diffusion based dehydration of a granular bed of Na2SO4·10H2O is shown to be internally limited as larger grains dehydrate faster than

  1. Assessing the conditions favorable for the occurrence of gas hydrate in the Tuonamu area Qiangtang basin, Qinghai–Tibetan, China

    International Nuclear Information System (INIS)

    He Jianglin; Wang Jian; Fu Xiugen; Zheng Chenggang; Chen Yanting

    2012-01-01

    Highlights: ► This is a pioneer research on the exploration of gas hydrate in Qiangtang basin. ► The factors influencing the stable of gas hydrate in Tuonamu area were studied. ► Simulation shows that gas hydrate stable zone is about 300 m thick in target area. ► Source condition is the key factor for the formation of gas hydrate in this area. ► The areas around the deeper faults are favorable targets for gas hydrate. - Abstract: Qiangtang basin, which is located in the largest continuous permafrost area in Qinghai–Tibetan Plateau, is expected to be a strategic area of gas hydrate exploitation in China. However, relatively little work has been done on the exploration of gas hydrate in this area. In this work, we evaluated the factors controlling the formation of gas hydrate in the Tuonamu area and provided a preliminary insight into gas hydrate distribution in it on the basis of the core samples, seismic data and laboratory analysis. It can be concluded that the source rock in the deeper formation would be dominant thermogenic source for the formation of gas hydrate in Tuonamu area. The thickness of gas hydrate stable zone in this area is about 300 m. The gas hydrate in the area most probably is in the form of gas-hydrate-water. The source condition is the key factor for the formation of gas hydrate and the gas hydrate layer would be mainly present in the form of interlayer in this area. The areas around the deeper faults are the favorable targets for the exploration of gas hydrate in the Tuonamu area.

  2. Thermodynamic studies on semi-clathrate hydrates of TBAB + gases containing carbon dioxide

    International Nuclear Information System (INIS)

    Eslamimanesh, Ali

    2012-01-01

    CO 2 capture has become an important area of research mainly due to its drastic greenhouse effects. Gas hydrate formation as a separation technique shows tremendous potential, both from a physical feasibility as well as an envisaged lower energy utilization criterion. Briefly, gas (clathrate) hydrates are non-stoichiometric, ice-like crystalline compounds formed through a combination of water and suitably sized guest molecule(s) under low-temperatures and elevated pressures. As the pressure required for gas hydrate formation is generally high, therefore, aqueous solution of tetra-n-butyl ammonium bromide (TBAB) is added to the system as a gas hydrate promoter. TBAB generally reduces the required hydrate formation pressure and/or increases the formation temperature as well as modifies the selectivity of hydrate cages to capture CO 2 molecules. TBAB also takes part in the hydrogen-bonded cages. Such hydrates are called 'semi-clathrate' hydrates. Evidently, reliable and accurate phase equilibrium data, acceptable thermodynamic models, and other thermodynamic studies should be provided to design efficient separation processes using the aforementioned technology. For this purpose, phase equilibria of clathrate/semi-clathrate hydrates of various gas mixtures containing CO 2 (CO 2 + CH 4 /N 2 /H 2 ) in the presence of pure water and aqueous solutions of TBAB have been measured in this thesis. In the theoretical section of the thesis, a thermodynamic model on the basis of the van der Waals and Platteeuw (vdW-P) solid solution theory along with the modified equations for determination of the Langmuir constants of the hydrate formers has been successfully developed to represent/predict equilibrium conditions of semi-clathrate hydrates of CO 2 , CH 4 , and N 2 . Later, several thermodynamic consistency tests on the basis of Gibbs-Duhem equation as well as a statistical approach have been applied on the phase equilibrium data of the systems of mixed/simple clathrate hydrates

  3. 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.

  4. 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.

  5. Obsidian hydration dates glacial loading?

    Science.gov (United States)

    Friedman, I; Pierce, K L; Obradovich, J D; Long, W D

    1973-05-18

    Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.

  6. On the conditions of preparation of hydrated rare earth orthovanadates

    Energy Technology Data Exchange (ETDEWEB)

    Nakhodnova, A P; Belousova, E E; Shuba, Yu I; Zaslavskij, L V

    1988-10-01

    The properties of Ln(NO/sub 3/)/sub 3/-Na/sub 3/VO/sub 4/-H/sub 2/O solution series, where Ln is Er, Ho, Eu are investigated by the methods of residual concentrations, conductometry and potentiometry. It is found that at equivalent ratios of the initial components LnVO/sub 4/xmH/sub 2/O hydrated orthovanadates are formed. Deviations towards excess of rare earths or vanadium result in contamination of the compounds by products of side reactions. According to the data on X-ray phase analysis, hydrated erbium, holmium, europium orthovanadates have the zirconium crystal structure typical for anhydrous compounds. It is shown that hydrate water, being a component of orthovanadates, can be referred to adsorbed and interlayer water.

  7. On the conditions of preparation of hydrated rare earth orthovanadates

    International Nuclear Information System (INIS)

    Nakhodnova, A.P.; Belousova, E.E.; Shuba, Yu.I.; Zaslavskij, L.V.

    1988-01-01

    The properties of Ln(NO 3 ) 3 -Na 3 VO 4 -H 2 O solution series, where Ln is Er, Ho, Eu are investigated by the methods of residual concentrations, conductometry and potentiometry. It is found that at equivalent ratios of the initial components LnVO 4 xmH 2 O hydrated orthovanadates are formed. Deviations towards excess of rare earths or vanadium result in contamination of the compounds by products of side reactions. According to the data on X-ray phase analysis, hydrated erbium, holmium, europium orthovanadates have the zirconium crystal structure typical for anhydrous compounds. It is shown that hydrate water, being a component of orthovanadates, can be referred to adsorbed and interlayer water

  8. 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

  9. Role of interlayer hydration in lincomycin sorption by smectite clays.

    Science.gov (United States)

    Wang, Cuiping; Ding, Yunjie; Teppen, Brian J; Boyd, Stephen A; Song, Cunyi; Li, Hui

    2009-08-15

    Lincomycin, an antibiotic widely administered as a veterinary medicine, is frequently detected in water. Little is known about the soil-water distribution of lincomycin despite the fact that this is a major determinant of its environmental fate and potential for exposure. Cation exchange was found to be the primary mechanism responsible for lincomycin sorption by soil clay minerals. This was evidenced by pH-dependent sorption, and competition with inorganic cations for sorptive sites. As solution pH increased, lincomycin sorption decreased. The extent of reduction was consistent with the decrease in cationic lincomycin species in solution. The presence of Ca2+ in solution diminished lincomycin sorption. Clay interlayer hydration status strongly influenced lincomycin adsorption. Smectites with the charge deficit from isomorphic substitution in tetrahedral layers (i.e., saponite) manifest a less hydrated interlayer environment resulting in greater sorption than that by octahedrally substituted clays (i.e., montmorillonite). Strongly hydrated exchangeable cations resulted in a more hydrated clay interlayer environment reducing sorption in the order of Ca- smectite. X-ray diffraction revealed that lincomycin was intercalated in smectite clay interlayers. Sorption capacity was limited by clay surface area rather than by cation exchange capacity. Smectite interlayer hydration was shown to be a major, yet previously unrecognized, factor influencing the cation exchange process of lincomycin on aluminosilicate mineral surfaces.

  10. Tritium-exchange method for obsidian hydration shell measurement

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, J P; Wilson, A T; Lowe, D J; Hodder, A P.W. [Waikato Univ., Hamilton (New Zealand)

    1984-12-01

    A new radiochemical method for measuring the amount of water in the hydrated layer on the surface of obsidians exchanges tritiated water with the water in the layer (20 ..mu..l of 5 Ci ml/sup -1/ at 90/sup 0/C for 10 days) and then back-exchanges it (in 150 ml of water at 35/sup 0/C for approx. 200 hr.). The activity of the back-exchange water (F) is monitored by liquid scintillation counting of aliquots extracted at known time intervals (t). The activity so measured is then related to the thickness of the hydration rim. A sheet diffusion model shows that the thickness of the hydration shell (l) is inversely proportional to the slope of the F vs. tsup(1/2) plot. Comparison of l-values so obtained between obsidians, whose age (x) is inferred from archaeological occupation layers containing radiocarbon-dated wood and charcoal, suggests a relationship between l and x. Implications for New Zealand prehistory are briefly considered. The technique, which is non-destructive, appears particularly applicable to young glasses where the development of hydrated layers may be inadequate for accurate optical measurement.