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Sample records for cytotoxic molten globules

  1. Molten globules, entropy-driven conformational change and protein folding.

    PubMed

    Baldwin, Robert L; Rose, George D

    2013-02-01

    The exquisite side chain close-packing in the protein core and at binding interfaces has prompted a conviction that packing selectivity is the primary mechanism for molecular recognition in folding and/or binding reactions. Contrary to this view, molten globule proteins can adopt native topology and bind targets tightly and specifically in the absence of side chain close-packing. The molten globule is a highly dynamic form with native-like secondary structure and a loose protein core that admits solvent. The related (but still controversial) dry molten globule is an expanded form of the native protein with largely intact topology but a tighter protein core that excludes solvent. Neither form retains side chain close-packing, and therefore both structure and function must result from other factors, assuming that the reality of the dry molten globule is accepted. This simplifying realization calls for a re-evaluation of established models. PMID:23237704

  2. Is the Molten Globule a Third Phase of Proteins?

    NASA Astrophysics Data System (ADS)

    Pande, Vijay S.; Rokhsar, Daniel S.

    1998-02-01

    The equilibrium properties of proteins are studied by Monte Carlo simulation of two simplified models of protein-like heteropolymers. These models emphasize the polymeric entropy of the fluctuating polypeptide chain. Our calculations suggest a generic phase diagram that contains a thermodynamically distinct ``molten globule'' state in addition to a rigid native state and a nontrivial unfolded state. The roles of side-chain packing and loop entropy are discussed.

  3. Crystallization of a designed peptide from a molten globule ensemble.

    PubMed

    Betz; Raleigh; DeGrado; Lovejoy; Anderson; Ogihara; Eisenberg

    1995-01-01

    Backgound. The design of amino acid sequences that adopt a desired three-dimensional fold has been of keen interest over the past decade. However, the design of proteins that adopt unique conformations is still a considerable problem. Until very recently, all of the designed proteins that have been extensively characterized possess the hallmarks of the molten globular state. Molten globular intermediates have been observed in both equilibrium and kinetic protein folding/stability studies, and understanding the forces that determine compact non-native states is critical for a comprehensive understanding of proteins. This paper describes the solution and early solid state characterization of peptides that form molten globular ensembles. Results. Crystals diffracting to 3.5Å resolution have been grown of a 16-residue peptide (alpha1A) designed to form a tetramer of alpha-helices. In addition, a closely related peptide, alpha1, has previously been shown to yield crystals that diffract to 1.2Å resolution. The solution properties of these two peptides were examined to determine whether their well defined crystalline conformations were retained in solution. On the basis of an examination of their NMR spectra, sedimentation equilibria, thermal unfolding, and ANS binding, it is concluded that the peptides form alpha-helical aggregates with properties similar to those of the molten globule state. Thus, for these peptides, the process of crystallization bears many similarities to models of protein folding. Upon dissolution, the peptides rapidly assume compact molten globular states similar to the molten globule like intermediates that are formed at short times after refolding is initiated. Following a rate-determining nucleation step, the peptides crystallize into a single or a small number of conformations in a process that mimics the formation of native structure in proteins. PMID:9162140

  4. Electrochemical evidence on the molten globule conformation of cytochrome c.

    PubMed

    Pineda, T; Sevilla, J M; Román, A J; Blázquez, M

    1997-12-01

    To explore a new approach for characterizing the molten globule conformation, cyclic voltammetric studies of salt induced transitions at acidic pH of cyt c have been carried out. The use of modified electrodes has made the observation of direct electrochemistry in native cyt c possible. However, most of these electrodes do not show reversible responses at acidic pH, due to the fact that, for this system, a deprotonated electrode surface is needed. In these studies, we have used a 6-mercaptopurine and cysteine-modified gold electrodes which are effective for direct rapid electron transfer to cyt c, even in acid solutions. The change in the absorption bands of cyt c are used to monitor the conformational states and, hence, to compare the voltammetric results. Under the experimental conditions where the A state of cyt c is obtained, a reversible voltammetric signal is observed. The midpoint peak potentials are found to be very close to the formal potential of native cyt c. Results are discussed in terms of a cooperative two-state transition between the acid unfolded and the globular acidic states of cyt c. This finding establishes, for the first time, the similarity of both the native and the molten globule-like conformations in terms of its redox properties. PMID:9434113

  5. Electrochemical evidence on the molten globule conformation of cytochrome c.

    PubMed

    Pineda, T; Sevilla, J M; Román, A J; Blázquez, M

    1997-12-01

    To explore a new approach for characterizing the molten globule conformation, cyclic voltammetric studies of salt induced transitions at acidic pH of cyt c have been carried out. The use of modified electrodes has made the observation of direct electrochemistry in native cyt c possible. However, most of these electrodes do not show reversible responses at acidic pH, due to the fact that, for this system, a deprotonated electrode surface is needed. In these studies, we have used a 6-mercaptopurine and cysteine-modified gold electrodes which are effective for direct rapid electron transfer to cyt c, even in acid solutions. The change in the absorption bands of cyt c are used to monitor the conformational states and, hence, to compare the voltammetric results. Under the experimental conditions where the A state of cyt c is obtained, a reversible voltammetric signal is observed. The midpoint peak potentials are found to be very close to the formal potential of native cyt c. Results are discussed in terms of a cooperative two-state transition between the acid unfolded and the globular acidic states of cyt c. This finding establishes, for the first time, the similarity of both the native and the molten globule-like conformations in terms of its redox properties.

  6. Redefining the dry molten globule state of proteins.

    PubMed

    Neumaier, Sabine; Kiefhaber, Thomas

    2014-06-26

    Dynamics and function of proteins are governed by the structural and energetic properties of the different states they adopt and the barriers separating them. In earlier work, native-state triplet-triplet energy transfer (TTET) on the villin headpiece subdomain (HP35) revealed an equilibrium between a locked native state and an unlocked native state, which are structurally similar but have different dynamic properties. The locked state is restricted to low amplitude motions, whereas the unlocked state shows increased conformational flexibility and undergoes local unfolding reactions. This classified the unlocked state as a dry molten globule (DMG), which was proposed to represent an expanded native state with loosened side-chain interactions and a solvent-shielded core. To test whether the unlocked state of HP35 is actually expanded compared to the locked state, we performed high-pressure TTET measurements. Increasing pressure shifts the equilibrium from the locked toward the unlocked state, with a small negative reaction volume for unlocking (ΔV(0)=-1.6±0.5cm(3)/mol). Therefore, rather than being expanded, the unlocked state represents an alternatively packed, compact state, demonstrating that native proteins can exist in several compact folded states, an observation with implications for protein function. The transition state for unlocking/locking, in contrast, has a largely increased volume relative to the locked and unlocked state, with respective activation volumes of 7.1±0.4cm(3)/mol and 8.7±0.9cm(3)/mol, indicating an expansion of the protein during the locking/unlocking transition. The presented results demonstrate the existence of both compact, low-energy and expanded, high-energy DMGs, prompting a broader definition of this state. PMID:24792909

  7. Formation of domain-swapped oligomer of cytochrome C from its molten globule state oligomer.

    PubMed

    Deshpande, Megha Subhash; Parui, Partha Pratim; Kamikubo, Hironari; Yamanaka, Masaru; Nagao, Satoshi; Komori, Hirofumi; Kataoka, Mikio; Higuchi, Yoshiki; Hirota, Shun

    2014-07-22

    Many proteins, including cytochrome c (cyt c), have been shown to form domain-swapped oligomers, but the factors governing the oligomerization process remain unrevealed. We obtained oligomers of cyt c by refolding cyt c from its acid molten globule state to neutral pH state under high protein and ion concentrations. The amount of oligomeric cyt c obtained depended on the nature of the anion (chaotropic or kosmotropic) in the solution: ClO4(-) (oligomers, 11% ± 2% (heme unit)), SCN(-) (10% ± 2%), I(-) (6% ± 2%), NO3(-) (3% ± 1%), Br(-) (2% ± 1%), Cl(-) (2% ± 1%), and SO4(2-) (3% ± 1%) for refolding of 2 mM cyt c (anion concentration 125 mM). Dimeric cyt c obtained by refolding from the molten globule state exhibited a domain-swapped structure, in which the C-terminal α-helices were exchanged between protomers. According to small-angle X-ray scattering measurements, approximately 25% of the cyt c molecules were dimerized in the molten globule state containing 125 mM ClO4(-). These results indicate that a certain amount of molten globule state oligomers of cyt c convert to domain-swapped oligomers during refolding and that the intermolecular interactions necessary for domain swapping are present in the molten globule state. PMID:24981551

  8. Individual subunits of bacterial luciferase are molten globules and interact with molecular chaperones.

    PubMed Central

    Flynn, G C; Beckers, C J; Baase, W A; Dahlquist, F W

    1993-01-01

    We have studied the assembly of a large heterodimeric protein, bacterial luciferase, by mixing purified subunits expressed separately in bacteria. The individual subunits alpha and beta contain much (66% and 50%, respectively) of the alpha-helix content of the native heterodimer as measured by circular dichroism, yet the alpha subunit lacks observable tertiary structure as measured by NMR. These results are consistent with the alpha subunit existing in a molten globule or collapsed form prior to assembly. The molecular chaperone GroEL binds reversibly to both subunits prior to assembly. Since these observations were obtained under physiological conditions, we propose that the molten globule exists as a stable form during folding or assembly in the cell. Either the molten globule form of the subunits is an authentic folding intermediate or it is in rapid equilibrium with one. GroEL may function by facilitating assembly through stabilization of these incompletely folded subunits. Images Fig. 4 PMID:7902573

  9. Topological switching between an alpha-beta parallel protein and a remarkably helical molten globule.

    PubMed

    Nabuurs, Sanne M; Westphal, Adrie H; aan den Toorn, Marije; Lindhoud, Simon; van Mierlo, Carlo P M

    2009-06-17

    Partially folded protein species transiently exist during folding of most proteins. Often these species are molten globules, which may be on- or off-pathway to native protein. Molten globules have a substantial amount of secondary structure but lack virtually all the tertiary side-chain packing characteristic of natively folded proteins. These ensembles of interconverting conformers are prone to aggregation and potentially play a role in numerous devastating pathologies, and thus attract considerable attention. The molten globule that is observed during folding of apoflavodoxin from Azotobacter vinelandii is off-pathway, as it has to unfold before native protein can be formed. Here we report that this species can be trapped under nativelike conditions by substituting amino acid residue F44 by Y44, allowing spectroscopic characterization of its conformation. Whereas native apoflavodoxin contains a parallel beta-sheet surrounded by alpha-helices (i.e., the flavodoxin-like or alpha-beta parallel topology), it is shown that the molten globule has a totally different topology: it is helical and contains no beta-sheet. The presence of this remarkably nonnative species shows that single polypeptide sequences can code for distinct folds that swap upon changing conditions. Topological switching between unrelated protein structures is likely a general phenomenon in the protein structure universe.

  10. Effect of galactose on acid induced molten globule state of Soybean Agglutinin: Biophysical approach

    NASA Astrophysics Data System (ADS)

    Alam, Parvez; Naseem, Farha; Abdelhameed, Ali Saber; Khan, Rizwan Hasan

    2015-11-01

    In the present study the formation of molten globule-like unfolding intermediate Soybean Agglutinin (SBA) in acidic pH range has been established with the help of acrylamide quenching, intrinsic fluorescence, ANS fluorescence measurement, far UV CD and dynamic light scattering measurement. A marked increase in ANS fluorescence was observed at pH 2.2. Ksv of acrylamide quenching was found to be higher at pH 2.2 than that of native SBA at pH 7. Far UV CD spectra of pH induced state suggest that SBA shows significant retention of secondary structure closure to native. Hydrodynamic radius of SBA at pH 2.2 was found be more as compared to native state and also in other pH induced states. Further we checked the effect of galactose on the molten globule state of SBA. This study suggests that SBA exist as molten globule at pH 2.2 and this study will help in acid induced molten globule state of other proteins.

  11. Illuminating the off-pathway nature of the molten globule folding intermediate of an α-β parallel protein.

    PubMed

    Lindhoud, Simon; Westphal, Adrie H; Borst, Jan Willem; van Mierlo, Carlo P M

    2012-01-01

    Partially folded protein species transiently form during folding of most proteins. Often, these species are molten globules, which may be on- or off-pathway to the native state. Molten globules are ensembles of interconverting protein conformers that have a substantial amount of secondary structure, but lack virtually all tertiary side-chain packing characteristics of natively folded proteins. Due to solvent-exposed hydrophobic groups, molten globules are prone to aggregation, which can have detrimental effects on organisms. The molten globule observed during folding of the 179-residue apoflavodoxin from Azotobacter vinelandii is off-pathway, as it has to unfold before native protein can form. Here, we study folding of apoflavodoxin and characterize its molten globule using fluorescence spectroscopy and Förster Resonance Energy Transfer (FRET). Apoflavodoxin is site-specifically labeled with fluorescent donor and acceptor dyes, utilizing dye-inaccessibility of Cys69 in cofactor-bound protein. Donor (i.e., Alexa Fluor 488) is covalently attached to Cys69 in all apoflavodoxin variants used. Acceptor (i.e., Alexa Fluor 568) is coupled to Cys1, Cys131 and Cys178, respectively. Our FRET data show that apoflavodoxin's molten globule forms in a non-cooperative manner and that its N-terminal 69 residues fold last. In addition, striking conformational differences between molten globule and native protein are revealed, because the inter-label distances sampled in the 111-residue C-terminal segment of the molten globule are shorter than observed for native apoflavodoxin. Thus, FRET sheds light on the off-pathway nature of the molten globule during folding of an α-β parallel protein. PMID:23029219

  12. Effect of Carbonic Anhydrase II in Molten Globule State on Physical Properties of Dimyristoylphosphatidylcholine Liposome

    NASA Astrophysics Data System (ADS)

    Sakai, Hiroko; Tanaka, Michiko; Imai, Kenichiro; Sonoyama, Masashi; Mitaku, Shigeki

    2001-05-01

    Ultrasonic relaxation measurement was employed for confirmation of the interaction between dimyristoylphosphatidylcholine (DMPC) membrane and a soluble protein, carbonic anhydrase II (CA II). The enhancement of the fluctuation of DMPC membrane structure was observed in the presence of CA II under acidic condition, pH 3.6-4, indicating the interaction between DMPC and CA II@. The pyrene fluorescence spectrum of CA II solution clearly showed that this protein adopted an unfolding intermediate called the molten globule state under the low pH condition, in which CA II interacted with DMPC@. However, CA II in the molten globule state did not cause membrane lysis in contrast to the high lytic activity of α-lactalbumin on DMPC liposomes.

  13. Hexafluoroacetone hydrate as a structure modifier in proteins: characterization of a molten globule state of hen egg-white lysozyme.

    PubMed Central

    Bhattacharjya, S.; Balaram, P.

    1997-01-01

    A molten globule-like state of hen egg-white lysozyme has been characterized in 25% aqueous hexafluoroacetone hydrate (HFA) by CD, fluorescence, NMR, and H/D exchange experiments. The far UV CD spectra of lysozyme in 25% HFA supports retention of native-like secondary structure while the loss of near UV CD bands are indicative of the overall collapse of the tertiary structure. The intermediate state in 25% HFA exhibits an enhanced affinity towards the hydrophobic dye, ANS, and a native-like tryptophan fluorescence quenching. 1-D NMR spectra indicates loss of native-like tertiary fold as evident from the absence of ring current-shifted 1H resonances. CD, fluorescence, and NMR suggest that the transition from the native state to a molten globule state in 25% HFA is a cooperative process. A second structural transition from this compact molten globule-like state to an "open" helical state is observed at higher concentrations of HFA (> or = 50%). This transition is characterized by a dramatic loss of ANS binding with a concomitant increase in far UV CD bands. The thermal unfolding of the molten globule state in 25% HFA is sharply cooperative, indicating a predominant role of side-chain-side-chain interactions in the stability of the partially folded state. H/D exchange experiments yield higher protection factors for many of the backbone amide protons from the four alpha-helices along with the C-terminal 3(10) helix, whereas little or no protection is observed for most of the amide protons from the triple-stranded antiparallel beta-sheet domain. This equilibrium molten globule-like state of lysozyme in 25% HFA is remarkably similar to the molten globule state observed for alpha-lactalbumin and also with the molten globule state transiently observed in the kinetic refolding experiments of hen lysozyme. These results suggest that HFA may prove generally useful as a structure modifier in proteins. PMID:9144778

  14. Existence of molten globule state in homocysteine-induced protein covalent modifications.

    PubMed

    Kumar, Tarun; Sharma, Gurumayum Suraj; Singh, Laishram Rajendrakumar

    2014-01-01

    Homocysteine thiolactone is a toxic metabolite produced from homocysteine by amino-acyl t-RNA synthetase in error editing reaction. The basic cause of toxicity of homocysteine thiolactone is believed to be due to the adduct formation with lysine residues (known as protein N-homocysteinylation) leading to protein aggregation and loss of enzyme function. There was no data available until now that showed the effect of homocysteine thiolactone on the native state structural changes that led to aggregate formation. In the present study we have investigated the time dependent structural changes due to homocysteine thiolactone induced modifications on three different proteins having different physico-chemical properties (cytochrome-c, lysozyme and alpha lactalbumin). We discovered that N-homocysteinylation leads to the formation of molten globule state--an important protein folding intermediate in the protein folding pathway. We also found that the formation of the molten globule state might be responsible for the appearance of aggregate formation. The study indicates the importance of protein folding intermediate state in eliciting the homocysteine thiolactone toxicity. PMID:25405350

  15. Effects of pressure on the structure of metmyoglobin: molecular dynamics predictions for pressure unfolding through a molten globule intermediate.

    PubMed Central

    Floriano, W. B.; Nascimento, M. A.; Domont, G. B.; Goddard, W. A.

    1998-01-01

    We investigated the pathway for pressure unfolding of metmyoglobin using molecular dynamics (MD) for a range of pressures (0.1 MPa to 1.2 GPa) and a temperature of 300 K. We find that the unfolding of metmyoglobin proceeds via a two-step mechanism native --> molten globule intermediate --> unfolded, where the molten globule forms at 700 MPa. The simulation describes qualitatively the experimental behavior of metmyoglobin under pressure. We find that unfolding of the alpha-helices follows the sequence of migrating hydrogen bonds (i,i + 4) --> (i,i + 2). PMID:9827996

  16. Capturing molten globule state of α-lactalbumin through constant pH molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Nicholus; Rani, Pooja; Biswas, Parbati

    2013-03-01

    The recently developed methods of constant pH molecular dynamics directly captures the correlation between protonation and conformation to probe protein structure, function, and dynamics. In this work, we investigate the effect of pH on the conformational properties of the protein human α-lactalbumin. Constant pH simulations at both acidic and alkaline medium indicate the formation of the molten globule state, which is in accordance with the previous experimental observations (especially, in acidic medium). The size of the protein measured by its radius of gyration (RG) exhibits a marked increase in both acidic and alkaline medium, which matches with the corresponding experimentally observed value of RG found in the molten globule. The probability of native contacts is also considerably reduced at acidic and basic pH as compared to that of native structure crystallized at neutral pH. The mean fractal dimension D2 of the protein records a sharp increase in basic medium as compared to those in neutral and acidic solutions implying a significant pH induced conformational change. The mean square fluctuations of all residues of the entire protein are found to increase by several folds in both acidic and basic medium, which may be correlated with the normalized solvent accessibility of the residues indicating role of solvent accessible surface area on protein internal dynamics. The helices comprising the α-domain of the protein are moderately preserved in the acidic and alkaline pH. However, the β-sheet structures present in the β-domain are completely disrupted in both acidic as well as basic pH.

  17. Differential role of molten globule and protein folding in distinguishing unique features of botulinum neurotoxin.

    PubMed

    Kumar, Raj; Kukreja, Roshan V; Cai, Shuowei; Singh, Bal R

    2014-06-01

    Botulinum neurotoxins (BoNTs) are proteins of great interest not only because of their extreme toxicity but also paradoxically for their therapeutic applications. All the known serotypes (A-G) have varying degrees of longevity and potency inside the neuronal cell. Differential chemical modifications such as phosphorylation and ubiquitination have been suggested as possible mechanisms for their longevity, but the molecular basis of the longevity remains unclear. Since the endopeptidase domain (light chain; LC) of toxin apparently survives inside the neuronal cells for months, it is important to examine the structural features of this domain to understand its resistance to intracellular degradation. Published crystal structures (both botulinum neurotoxins and endopeptidase domain) have not provided adequate explanation for the intracellular longevity of the domain. Structural features obtained from spectroscopic analysis of LCA and LCB were similar, and a PRIME (PReImminent Molten Globule Enzyme) conformation appears to be responsible for their optimal enzymatic activity at 37°C. LCE, on the other hand, was although optimally active at 37°C, but its active conformation differed from the PRIME conformation of LCA and LCB. This study establishes and confirms our earlier finding that an optimally active conformation of these proteins in the form of PRIME exists for the most poisonous poison, botulinum neurotoxin. There are substantial variations in the structural and functional characteristics of these active molten globule related structures among the three BoNT endopeptidases examined. These differential conformations of LCs are important in understanding the fundamental structural features of proteins, and their possible connection to intracellular longevity could provide significant clues for devising new countermeasures and effective therapeutics. PMID:24568862

  18. Evidence for close side-chain packing in an early protein folding intermediate previously assumed to be a molten globule

    PubMed Central

    Rosen, Laura E.; Connell, Katelyn B.; Marqusee, Susan

    2014-01-01

    The molten globule, a conformational ensemble with significant secondary structure but only loosely packed tertiary structure, has been suggested to be a ubiquitous intermediate in protein folding. However, it is difficult to assess the tertiary packing of transiently populated species to evaluate this hypothesis. Escherichia coli RNase H is known to populate an intermediate before the rate-limiting barrier to folding that has long been thought to be a molten globule. We investigated this hypothesis by making mimics of the intermediate that are the ground-state conformation at equilibrium, using two approaches: a truncation to generate a fragment mimic of the intermediate, and selective destabilization of the native state using point mutations. Spectroscopic characterization and the response of the mimics to further mutation are consistent with studies on the transient kinetic intermediate, indicating that they model the early intermediate. Both mimics fold cooperatively and exhibit NMR spectra indicative of a closely packed conformation, in contrast to the hypothesis of molten tertiary packing. This result is important for understanding the nature of the subsequent rate-limiting barrier to folding and has implications for the assumption that many other proteins populate molten globule folding intermediates. PMID:25258414

  19. Evidence for close side-chain packing in an early protein folding intermediate previously assumed to be a molten globule.

    PubMed

    Rosen, Laura E; Connell, Katelyn B; Marqusee, Susan

    2014-10-14

    The molten globule, a conformational ensemble with significant secondary structure but only loosely packed tertiary structure, has been suggested to be a ubiquitous intermediate in protein folding. However, it is difficult to assess the tertiary packing of transiently populated species to evaluate this hypothesis. Escherichia coli RNase H is known to populate an intermediate before the rate-limiting barrier to folding that has long been thought to be a molten globule. We investigated this hypothesis by making mimics of the intermediate that are the ground-state conformation at equilibrium, using two approaches: a truncation to generate a fragment mimic of the intermediate, and selective destabilization of the native state using point mutations. Spectroscopic characterization and the response of the mimics to further mutation are consistent with studies on the transient kinetic intermediate, indicating that they model the early intermediate. Both mimics fold cooperatively and exhibit NMR spectra indicative of a closely packed conformation, in contrast to the hypothesis of molten tertiary packing. This result is important for understanding the nature of the subsequent rate-limiting barrier to folding and has implications for the assumption that many other proteins populate molten globule folding intermediates. PMID:25258414

  20. The unfolding enthalpy of the pH 4 molten globule of apomyoglobin measured by isothermal titration calorimetry.

    PubMed Central

    Jamin, M.; Antalik, M.; Loh, S. N.; Bolen, D. W.; Baldwin, R. L.

    2000-01-01

    The unfolding enthalpy of the pH 4 molten globule from sperm whale apomyoglobin has been measured by isothermal titration calorimetry, using titration to acid pH. The unfolding enthalpy is close to zero at 20 degrees C, in contrast both to the positive values expected for peptide helices and the negative values reported for holomyoglobin and native apomyoglobin. At 20 degrees C, the hydrophobic interaction should make only a small contribution to the unfolding enthalpy according to the liquid hydrocarbon model. Our result indicates that some factor present in the unfolding enthalpies of native proteins makes the unfolding enthalpy of the pH 4 molten globule less positive than expected from data for peptide helices. PMID:10933499

  1. Effects of arginine on rabbit muscle creatine kinase and salt-induced molten globule-like state.

    PubMed

    Ou, Wen-bin; Wang, Ri-Sheng; Lu, Jie; Zhou, Hai-Meng

    2003-11-01

    The arginine (Arg)-induced unfolding and the salt-induced folding of creatine kinase (CK) have been studied by measuring enzyme activity, fluorescence emission spectra, native polyacrylamide gel electrophoresis and size exclusion chromatography (SEC). The results showed that Arg caused inactivation and unfolding of CK, but there was no aggregation during CK denaturation. The kinetics of CK unfolding followed a one-phase process. At higher concentrations of Arg (>160 mM), the CK dimers were fully dissociated, the alkali characteristic of Arg mainly led to the dissociation of dimers, but not denaturation effect of Arg's guanidine groups on CK. The inactivation of CK occurred before noticeable conformational changes of the whole molecules. KCl induced monomeric and dimeric molten globule-like states of CK denatured by Arg. These results suggest that as a protein denaturant, the effect of Arg on CK differed from that of guanidine and alkali, its denaturation for protein contains the double effects, which acts not only as guanidine hydrochloride but also as alkali. The active sites of CK have more flexibility than the whole enzyme conformation. Monomeric and dimeric molten globule-like states of CK were formed by the salt inducing in 160 and 500 mM Arg H(2)O solutions, respectively. The molten globule-like states indicate that monomeric and dimeric intermediates exist during CK folding. Furthermore, these results also proved the orderly folding model of CK.

  2. Characterization of the stable, acid-induced, molten globule-like state of staphylococcal nuclease.

    PubMed Central

    Fink, A. L.; Calciano, L. J.; Goto, Y.; Nishimura, M.; Swedberg, S. A.

    1993-01-01

    Titration of a salt-free solution of native staphylococcal nuclease by HCl leads to an unfolding transition in the vicinity of pH 4, as determined by near- and far-UV circular dichroism. At pH 2-3, the protein is substantially unfolded. The addition of further HCl results in a second transition, this one to a more structured species (the A state) with the properties of an expanded molten globule, namely substantial secondary structure, little or no tertiary structure, relatively compact size as determined by hydrodynamic radius, and the ability to bind the hydrophobic dye 1-anilino-8-naphthalene sulfonic acid. The addition of anions, in the form of neutral salts, to the acid-unfolded state at pH 2 also causes a transition leading to the A state. Fourier transform infrared analysis of the amide I band was used to compare the amount and type of secondary structure in the native and A states. A significant decrease in alpha-helix structure, with a corresponding increase in beta or extended structure, was observed in the A state, compared to the native state. A model to account for such compact denatured states is proposed. PMID:8358298

  3. A model of the molten globule state from molecular dynamics simulations.

    PubMed Central

    Daggett, V; Levitt, M

    1992-01-01

    It is generally accepted that a protein's primary sequence determines its three-dimensional structure. It has proved difficult, however, to obtain detailed structural information about the actual protein folding process and intermediate states. We present the results of molecular dynamics simulations of the unfolding of reduced bovine pancreatic trypsin inhibitor. The resulting partially "denatured" state was compact but expanded relative to the native state (11-25%); the expansion was not caused by an influx of water molecules. The structures were mobile, with overall secondary structure contents comparable to those of the native protein. The protein experienced relatively local unfolding, with the largest changes in the structure occurring in the loop regions. A hydrophobic core was maintained although packing of the side chains was compromised. The properties displayed in the simulation are consistent with unfolding to a molten globule state. Our simulations provide an in-depth view of this state and details of water-protein interactions that cannot yet be obtained experimentally. Images PMID:1594623

  4. Guanidine hydrochloride-induced alkali molten globule model of horse ferrocytochrome c.

    PubMed

    Jain, Rishu; Kaur, Sandeep; Kumar, Rajesh

    2013-02-01

    This article compares structural, kinetic and thermodynamic properties of previously unknown guanidine hydrochloride (GdnHCl)-induced alkali molten globule (MG) state of horse 'ferrocytochrome c' (ferrocyt c) with the known NaCl-induced alkali-MG state of ferrocyt c. It is well known that Cl(-) arising from GdnHCl refolds and stabilizes the acid-denatured protein to MG state. We demonstrate that the GdnH(+) arising from GdnHCl (≤0.2 M) also transforms the base-denatured CO-liganded ferrocyt c (carbonmonoxycyt c) to MG state by making the electrostatic interactions to the negative charges of the protein. Structural and molecular properties extracted from the basic spectroscopic (circular dichroism (CD), fluorescence, FTIR and NMR) experiments suggest that the GdnH(+)- and Na(+)-induced MG states of base-denatured carbonmonoxycyt c are molecular compact states containing native-like secondary structures and disordered tertiary structures. Kinetic experiments involving the measurement of the CO association to the alkaline ferrocyt c in the presence of different GdnHCl and NaCl concentrations indicate that the Na(+)-induced MG state is more constrained relative to that of GdnH(+)-induced MG state. Analyses of thermal (near UV-CD) denaturation curves of the base-denatured protein in the presence of different GdnHCl and NaCl concentration also indicate that the Na(+)-induced MG state is thermally more stable than the GdnH(+)-induced MG state.

  5. The alkali molten globule state of ferrocytochrome c: extraordinary stability, persistent structure, and constrained overall dynamics.

    PubMed

    Rao, D Krishna; Kumar, Rajesh; Yadaiah, M; Bhuyan, Abani K

    2006-03-14

    This paper describes the structural and dynamic properties of a hitherto uncovered alkali molten globule (MG) state of horse "ferrocytochrome c" (ferrocyt c). Several experimental difficulties mainly because of heme autoxidation and extraordinary stability of ferrocyt c have been overcome by working with the carbonmonoxide-bound molecule under extremely basic condition (pH 13) in a strictly anaerobic atmosphere. Structural and molecular properties extracted from basic spectroscopic experiments suggest that cations drive the base-denatured CO-liganded protein to the MG state. The stability of this state is approximately 5.2 kcal mol(-)(1), and the guanidinium-induced unfolding transition is sharp (m(g) approximately 2.3 kcal mol(-)(1) M(-)(1)), suggesting contents of rigid tertiary structure. Strategic experiments involving the measurement of the CO association rate to the base-denatured protein and intrachain diffusion rates measured by laser photolysis of CO indicate a substantially restricted overall motion and stiffness of the polypeptide chain in the MG state. Possible placement of the state in the folding coordinate of ferrocyt c is discussed.

  6. Gradual Folding of an Off-Pathway Molten Globule Detected at the Single-Molecule Level.

    PubMed

    Lindhoud, Simon; Pirchi, Menahem; Westphal, Adrie H; Haran, Gilad; van Mierlo, Carlo P M

    2015-09-25

    Molten globules (MGs) are compact, partially folded intermediates that are transiently present during folding of many proteins. These intermediates reside on or off the folding pathway to native protein. Conformational evolution during folding of off-pathway MGs is largely unexplored. Here, we characterize the denaturant-dependent structure of apoflavodoxin's off-pathway MG. Using single-molecule fluorescence resonance energy transfer (smFRET), we follow conversion of unfolded species into MG down to denaturant concentrations that favor formation of native protein. Under strongly denaturing conditions, fluorescence resonance energy transfer histograms show a single peak, arising from unfolded protein. The smFRET efficiency distribution shifts to higher value upon decreasing denaturant concentration because the MG folds. Strikingly, upon approaching native conditions, the fluorescence resonance energy transfer efficiency of the MG rises above that of native protein. Thus, smFRET exposes the misfolded nature of apoflavodoxin's off-pathway MG. We show that conversion of unfolded into MG protein is a gradual, second-order-like process that simultaneously involves separate regions within the polypeptide. PMID:26163276

  7. Reshaping the folding energy landscape by chloride salt: impact on molten-globule formation and aggregation behavior of carbonic anhydrase.

    PubMed

    Borén, Kristina; Grankvist, Hannah; Hammarström, Per; Carlsson, Uno

    2004-05-21

    During chemical denaturation different intermediate states are populated or suppressed due to the nature of the denaturant used. Chemical denaturation by guanidine-HCl (GuHCl) of human carbonic anhydrase II (HCA II) leads to a three-state unfolding process (Cm,NI=1.0 and Cm,IU=1.9 M GuHCl) with formation of an equilibrium molten-globule intermediate that is stable at moderate concentrations of the denaturant (1-2 M) with a maximum at 1.5 M GuHCl. On the contrary, urea denaturation gives rise to an apparent two-state unfolding transition (Cm=4.4 M urea). However, 8-anilino-1-naphthalene sulfonate (ANS) binding and decreased refolding capacity revealed the presence of the molten globule in the middle of the unfolding transition zone, although to a lesser extent than in GuHCl. Cross-linking studies showed the formation of moderate oligomer sized (300 kDa) and large soluble aggregates (>1000 kDa). Inclusion of 1.5 M NaCl to the urea denaturant to mimic the ionic character of GuHCl leads to a three-state unfolding behavior (Cm,NI=3.0 and Cm,IU=6.4 M urea) with a significantly stabilized molten-globule intermediate by the chloride salt. Comparisons between NaCl and LiCl of the impact on the stability of the various states of HCA II in urea showed that the effects followed what could be expected from the Hofmeister series, where Li+ is a chaotropic ion leading to decreased stability of the native state. Salt addition to the completely urea unfolded HCA II also led to an aggregation prone unfolded state, that has not been observed before for carbonic anhydrase. Refolding from this state only provided low recoveries of native enzyme.

  8. A molten globule intermediate of the von Willebrand factor A1 domain firmly tethers platelets under shear flow.

    PubMed

    Tischer, Alexander; Madde, Pranathi; Blancas-Mejia, Luis M; Auton, Matthew

    2014-05-01

    Clinical mutations in patients diagnosed with Type 2A von Willebrand disease (VWD) have been identified that break the single disulfide bond linking N- and C-termini in the vWF A1 domain. We have modeled the effect of these mutations on the disulfide-bonded structure of A1 by reducing and carboxy-amidating these cysteines. Solution biophysical studies show that loss of this disulfide bond induces a molten globule conformational state lacking global tertiary structure but retaining residual secondary structure. The conformational dependence of platelet adhesion to these native and molten globule states of A1 is quantitatively compared using real-time high-speed video microscopy analysis of platelet translocation dynamics under shear flow in a parallel plate microfluidic flow chamber. While normal platelets translocating on surface-captured native A1 domain retain the catch-bond character of pause times that increase as a function of shear rate at low shear and decrease as a function of shear rate at high shear, platelets that interact with A1 lacking the disulfide bond remain stably attached and do not translocate. Based on these findings, we propose that the shear stress-sensitive regulation of the A1-GPIb interaction is due to folding the tertiary structure of this domain. Removal of the tertiary structure by disrupting the disulfide bond destroys this regulatory mechanism resulting in high-strength interactions between platelets and vWF A1 that are dependent only on residual secondary structure elements present in the molten globule conformation. PMID:24265179

  9. Characterization of molten globule PopB in absence and presence of its chaperone PcrH.

    PubMed

    Dey, Supratim; Basu, Abhishek; Datta, Saumen

    2012-06-01

    The TTSS encoding "translocator operon" of Pseudomonas aeruginosa consists of a major translocator protein PopB, minor translocator protein PopD and their cognate chaperone PcrH. Far-UV CD spectra and secondary structure prediction servers predict an α-helical model for PopB, PcrH and PopB-PcrH complex. PopB itself forms a single species of higher order oligomer (15 mer) as seen from AUC, but in complex with PcrH, both monomeric (1:1) and oligomeric form exist. PopB has large solvent-exposed hydrophobic patches and exists as an unordered molten globule in its native state, but on forming complex with PcrH it gets transformed into an ordered molten globule. Tryptophan fluorescence spectrum indicates that PopB interacts with the first TPR region of dimeric PcrH to form a stable PopB-PcrH complex that has a partial rigid structure with a large hydrodynamic radius and few tertiary contacts. The pH-dependent studies of PopB, PcrH and complex by ANS fluorescence, urea induced unfolding and thermal denaturation experiments prove that PcrH not only provides structural support to the ordered molten globule PopB in complex but also undergoes conformational change to assist PopB to pass through the needle complex of TTSS and form pores in the host cell membrane. ITC experiments show a strong affinity (K(d) ~ 0.37 μM) of PopB for PcrH at pH 7.8, which reduces to ~0.68 μM at pH 5.8. PcrH also loses its rigid tertiary structure at pH 5 and attains a molten globule conformation. This indicates that the decrease in pH releases PopB molecules and thus triggers the TTSS activation mechanism for the formation of a functional translocon. PMID:22585368

  10. Observation of persistent α-helical content and discrete types of backbone disorder during a molten globule to ordered peptide transition via deep-UV resonance Raman spectroscopy

    PubMed Central

    Brown, Mia C.; Mutter, Andrew; Koder, Ronald L.; JiJi, Renee D.; Cooley, Jason W.

    2016-01-01

    The molten globule state can aide in the folding of a protein to a functional structure and is loosely defined as an increase in structural disorder with conservation of the ensemble secondary structure content. Simultaneous observation of persistent secondary structure content with increased disorder has remained experimentally problematic. As a consequence, modeling how the molten globule state remains stable and how it facilitates proper folding remains difficult due to a lack of amenable spectroscopic techniques to characterize this class of partially unfolded proteins. Previously, deep-UV resonance Raman (dUVRR) spectroscopy has proven useful in the resolution of global and local structural fluctuations in the secondary structure of proteins. In this work, dUVRR was employed to study the molten globule to ordered transition of a model four-helix bundle protein, HP7. Both the average ensemble secondary structure and types of local disorder were monitored, without perturbation of the solvent, pH, or temperature. The molten globule to ordered transition is induced by stepwise coordination of two heme molecules. Persistent dUVRR spectral features in the amide III region at 1295–1301 and 1335–1338 cm−1 confirm previous observations that HP7 remains predominantly helical in the molten globule versus the fully ordered state. Additionally, these spectra represent the first demonstration of conserved helical content in a molten globule protein. With successive heme binding significant losses are observed in the spectral intensity of the amide III3 and S regions (1230–1260 and 1390 cm−1, respectively), which are known to be sensitive to local disorder. These observations indicate that there is a decrease in the structural populations able to explore various extended conformations, with successive heme binding events. DUVRR spectra indicate that the first heme coordination between two helical segments diminishes exploration of more elongated backbone structural

  11. Nucleotide-free kinesin motor domains reversibly convert to an inactive conformation with characteristics of a molten globule.

    PubMed

    Hackney, David D; McGoff, Marshall S

    2016-10-15

    Nucleotide-free kinesin motor domains from several kinesin families convert reversibly to a refractory conformation that cannot rapidly rebind ADP. In the absence of glycerol, the refractory conformation of Drosophila kinesin motor domains is favored by 50-fold with conversion of the active to the refractory species at ∼0.052 s(-1) and reactivating in the presence of ADP at ∼0.001 s(-1). This reactivation by ADP is due to conformational selection rather than induced fit because ADP is not bound to the refractory species at concentrations of ADP that are sufficient to saturate the rate of reactivation. Glycerol stabilizes the active conformation by reducing the rate of inactivation, while having little effect on the reactivation rate. Circular dichroism indicates a large conformational change occurs on formation of the refractory species. The refractory conformation binds ANS (8-anilino-1-napthalenesulfonic acid) with a large increase in fluorescence, indicating that it has molten globule character. High ANS binding is also observed with the refractory forms of Eg5 (a kinesin-5) and Ncd (a kinesin-14), indicating that a refractory conformation with molten globule characteristics may be a common feature of nucleotide-free kinesin motor domains.

  12. A molten globule-like intermediate state detected in the thermal transition of cytochrome c under low salt concentration.

    PubMed

    Nakamura, Shigeyoshi; Baba, Takayuki; Kidokoro, Shun-Ichi

    2007-04-01

    To understand the stabilization mechanism of the transient intermediate state in protein folding, it is very important to understand the structure and stability of the molten globule state under a native condition, in which the native state exists stably. The thermal transitions of horse cytochrome c were thermodynamically evaluated by highly precise differential scanning calorimetry (DSC) at pH 3.8-5.0. The heat capacity functions were analyzed using double deconvolution and the nonlinear least-squares method. An intermediate (I) state is clearly confirmed in the thermal native (N)-to-denatured (D) transition of horse cytochrome c. The mole fraction of the intermediate state shows the largest value, 0.4, at nearly 70 degrees C at pH 4.1. This intermediate state was also detected by the circular dichroism (CD) method and was found to have the properties of the molten globule-like structure by three-state analysis of the CD data. The Gibbs free-energy change between N and I, DeltaG(NI), and that between N and D, DeltaG(ND), were evaluated to be 9-22 kJ mol(-1) and 41-45 kJ mol(-1), respectively at 15( ) degrees C and pH 4.1.

  13. Trifluoroethanol stabilizes the molten globule state and induces non-amyloidic turbidity in stem bromelain near its isoelectric point.

    PubMed

    Dave, Sandeep; Mahajan, Sahil; Chandra, Vemika; Gupta, Pawan

    2011-11-01

    Stem bromelain (SBM) is a therapeutic protein that has been studied for alkaline denaturation in the intestines, the principal site of its absorption. In this study, we investigated fluorinated alcohol 2,2,2-trifluoroethanol (TFE)-induced conformational changes in the specific/pre-molten globule (SMG) state of SBM observed at pH 10 by spectroscopic methods. Far-UV circular dichroism (CD) spectra showed that the protein retained its native-like secondary structure at TFE concentrations of up to 30% with a pronounced minimum at 222 nm, characteristic of a helix. However, addition of slightly higher TFE concentrations (≥40%) resulted in an ∼2.5-fold induction of this helical feature and a time-dependent increase in non-amyloidic turbidity as evidenced by turbidometric, Congo red-binding, and Thioflavin T (ThT)-binding studies. Near-UV CD spectra suggested a gradual but significant loss of tertiary structure at 10-30% TFE. Tryptophan studies showed blue-shifted fluorescence, although the number of accessible tryptophans remained the same up to 30% TFE. The SMG showed enhanced binding of the fluorescent probe 1-anilino-8-naphthalene sulfonic acid (ANS) up to 30% TFE, beyond which binding plateaued. Thermal and guanidine hydrochloride (GdnHCl) transition studies in the near-UV range indicated a single cooperative transition for the SMG state in the presence of 30% TFE, similar to that observed for native SBM at pH 7.0 (although with different T(m)s), unlike the SMG state. TFE (30%) appeared to induce native-like stability to the original SMG. These observations suggest a transformation of the SMG to a characteristic molten globule (MG) conformation at 30% TFE, possibly due to TFE-induced rearrangement of hydrophobic interactions at the protein's isoelectric point.

  14. 1-Anilino-8-naphthalene sulfonate (ANS) is not a desirable probe for determining the molten globule state of chymopapain.

    PubMed

    Qadeer, Atiyatul; Rabbani, Gulam; Zaidi, Nida; Ahmad, Ejaz; Khan, Javed M; Khan, Rizwan H

    2012-01-01

    The molten globule (MG) state of proteins is widely detected through binding with 1-anilino-8-naphthalene sulphonate (ANS), a fluorescent dye. This strategy is based upon the assumption that when in molten globule state, the exposed hydrophobic clusters of protein are readily bound by the nonpolar anilino-naphthalene moiety of ANS molecules which then produce brilliant fluorescence. In this work, we explored the acid-induced unfolding pathway of chymopapain, a cysteine proteases from Carica papaya, by monitoring the conformational changes over a pH range 1.0-7.4 by circular dichroism, intrinsic fluorescence, ANS binding, acrylamide quenching, isothermal titration calorimetry (ITC) and dynamic light scattering (DLS). The spectroscopic measurements showed that although maximum ANS fluorescence intensity was observed at pH 1.0, however protein exhibited ∼80% loss of secondary structure which does not comply with the characteristics of a typical MG-state. In contrast at pH 1.5, chymopapain retains substantial amount of secondary structure, disrupted side chain interactions, increased hydrodynamic radii and nearly 30-fold increase in ANS fluorescence with respect to the native state, indicating that MG-state exists at pH 1.5 and not at pH 1.0. ITC measurements revealed that ANS molecules bound to chymopapain via hydrophobic interaction were more at pH 1.5 than at pH 1.0. However, a large number of ANS molecules were also involved in electrostatic interaction with protein at pH 1.0 which, together with hydrophobically interacted molecules, may be responsible for maximum ANS fluorescence. We conclude that maximum ANS-fluorescence alone may not be the criteria for determining the MG of chymopapain. Hence a comprehensive structural analysis of the intermediate is essentially required. PMID:23209794

  15. Circularly permuted dihydrofolate reductase possesses all the properties of the molten globule state, but can resume functional tertiary structure by interaction with its ligands.

    PubMed Central

    Uversky, V. N.; Kutyshenko, V. P.; Protasova NYu; Rogov, V. V.; Vassilenko, K. S.; Gudkov, A. T.

    1996-01-01

    It is obvious that functional activity of a protein molecule is closely related to its structure. On the other hand, the understanding of structure-function relationship still remains one of the intriguing problems of molecular biology. There is widespread belief that mutagenesis presents a real way to solve this problem. Following this assumption, we have investigated the effect of circular permutation in dihydrofolate reductase from E. coli on protein structure and functioning. It has been shown that in the absence of ligands two circularly permuted variants of dihydrofolate reductase possess all the properties of the molten globule state. However, after addition of ligands they gain the native-like structural properties and specific activity. This means that the in vitro folding of permuted dihydrofolate reductase is terminated at the stage of the molten globule formation. Interaction of permuted protein with ligands leads to the structural adjustment and formation of active protein molecules. PMID:8880908

  16. Equilibrium titrations of acid-induced unfolding-refolding and salt-induced molten globule of cytochrome c by FT-IR spectroscopy.

    PubMed

    Dong, Aichun; Lam, Troy

    2005-04-01

    Despite extensive investigations on the acid-unfolded and acid/salt-induced molten globule(-like) states of cytochrome c using variety of techniques, structural features of the acid-unfolded state in terms of residual secondary structures and the structural transition between the acid-unfolded and acid/salt-refolded states have not been fully characterized beyond the circular dichroism (CD) spectroscopy. It is unusual that secondary structure(s) of the unfolded state leading to the molten globule state, an important protein folding intermediate, as determined by CD was not fully corroborated by independent experimental method(s). In this study, we carried out an equilibrium titration of acid-induced unfolding and subsequent acid- and salt-induced refolding of cytochrome c using Fourier transform infrared spectroscopy. The spectral profiles of the equilibrium titration reveal new structural details about the acid-unfolded state and the structural transition associated with the acid/salt-refolded molten globule(-like) states of cytochrome c.

  17. Characterization of sub-nanosecond dynamics of the molten globule state of α-lactalbumin using quasielastic neutron scattering and molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Tarek, Mounir; Neumann, Dan A.; Tobias, Douglas J.

    2003-08-01

    The dynamics of α-lactalbumin in the native and molten globule states in solution was investigated using quasielastic neutron scattering and molecular dynamics simulations. We generated 2 nanosecond molecular dynamics trajectories at 300 K of α-lactalbumin solvated in a water box in the native state, and a putative member of the ensemble of conformations of the molten globule state generated by simulation at high temperature. Overall the agreement between the measured and calculated dynamical structure factors is good. Preliminary analysis of the simulated dynamics of the molten globule state revealed a strong heterogeneity of motions along the protein backbone, with larger amplitudes in the regions of the protein that unfold, mainly the β-sheet region. The results presented here demonstrate the utility of using a combination of neutron scattering measurements and molecular dynamics simulations to characterize and quantify, in a sequence-specific fashion, the differences in dynamics between the native and partially folded states of proteins on the time scale (˜100 ps) and length scale (a few to tens of Å) probed by current neutron spectrometers.

  18. Effect of hydrostatic pressure on conformational changes of canine milk lysozyme between the native, molten globule, and unfolded states.

    PubMed

    Watanabe, Masahiro; Aizawa, Tomoyasu; Demura, Makoto; Nitta, Katsutoshi

    2004-11-01

    The effect of pressure on the unfolding of the native (N) and molten globule (MG) state of canine milk lysozyme (CML) was examined using ultraviolet (UV) spectroscopy at pH 4.5 and 2.0, respectively. It appeared that the thermally induced unfolding was promoted by the increase of pressure from atmospheric to 100 MPa, which indicates that both the N and MG states of CML unfolded with the decrease of the partial molar volume change (DeltaV). The volume changes needed for unfolding were estimated from the free energy change vs. pressure plots, and these volume changes became less negative from 20 to 60 degrees C. The DeltaV values at 25 degrees C were obtained for the N-MG (-46 cm3/mol) and MG-unfolded-state (U) transition (-40 cm3/mol). With regards to the MG-U transition, this value is contrastive to that of bovine alpha-lactalbumin (BLA) (0.9 cm3/mol), which is homologous to CML. Previous studies revealed that the MG state of CML was significantly more stable, and closer to the N state in structure, than that of BLA. In contrast to the swollen hydrophobic core of the MG state of BLA, our results suggest that the MG state of CML possesses a tightly packed hydrophobic core into which water molecules cannot penetrate. PMID:15488764

  19. Acid-induced molten globule state of a prion protein: crucial role of Strand 1-Helix 1-Strand 2 segment.

    PubMed

    Honda, Ryo P; Yamaguchi, Kei-ichi; Kuwata, Kazuo

    2014-10-31

    The conversion of a cellular prion protein (PrP(C)) to its pathogenic isoform (PrP(Sc)) is a critical event in the pathogenesis of prion diseases. Pathogenic conversion is usually associated with the oligomerization process; therefore, the conformational characteristics of the pre-oligomer state may provide insights into the conversion process. Previous studies indicate that PrP(C) is prone to oligomer formation at low pH, but the conformation of the pre-oligomer state remains unknown. In this study, we systematically analyzed the acid-induced conformational changes of PrP(C) and discovered a unique acid-induced molten globule state at pH 2.0 termed the "A-state." We characterized the structure of the A-state using far/near-UV CD, 1-anilino-8-naphthalene sulfonate fluorescence, size exclusion chromatography, and NMR. Deuterium exchange experiments with NMR detection revealed its first unique structure ever reported thus far; i.e. the Strand 1-Helix 1-Strand 2 segment at the N terminus was preferentially unfolded, whereas the Helix 2-Helix 3 segment at the C terminus remained marginally stable. This conformational change could be triggered by the protonation of Asp(144), Asp(147), and Glu(196), followed by disruption of key salt bridges in PrP(C). Moreover, the initial population of the A-state at low pH (pH 2.0-5.0) was well correlated with the rate of the β-rich oligomer formation, suggesting that the A-state is the pre-oligomer state. Thus, the specific conformation of the A-state would provide crucial insights into the mechanisms of oligomerization and further pathogenic conversion as well as facilitating the design of novel medical chaperones for treating prion diseases. PMID:25217639

  20. The Effect of pH on Globular State of Lipase-3646; an Appropriate Model for Molten Globule Investigations.

    PubMed

    Golaki, Bahram Pooreydy; Aminzadeh, Saeed; Karkhane, Ali Asghar; Yakhchali, Bagher; Farrokh, Parisa; Jazii, Ferdous Rastgar; Nadimifar, Mohammadsadegh

    2015-08-01

    Secondary structure content of proteins in molten globule state is relatively constant while the quantity of tertiary structures clearly declines due to alterations in side-chain packing. In the present study, we analyze the MG state of lipase-3646 for the first time. We introduce lipase-3646 as an appropriate model for investigating the properties and behavior of a protein in MG state as well as folding pathway. Applying fluorescence spectroscopy we measured both intrinsic and extrinsic fluorescence of lipase-3646 in a pH range from 1.0 to 12.0. It was found that at pH 3.0 the protein acquires a MG state. Applying far-UV circular dichroism (CD), our analysis on the secondary structure of lipase-3646 revealed a slight change in the MG state intermediate (pH 3.0) compared to the native state (pH 8.5), which this amount of change is common for MG. Measurements in near-UV CD also showed a significant change in the enzyme conformation at pH 3.0 in comparison with the pH 8.5 wherein the protein acquires its native structure. Quenching the fluorescence by applying acrylamide, the amount 23 and 35 M(-1) were measured at pHs 8.5 and 3.0 respectively for stern-volmer constant (KSV). An increase in the enzyme molecular volume in the MG state was confirmed by gel filtration chromatography. PMID:26239273

  1. The molten globule of β(2)-microglobulin accumulated at pH 4 and its role in protein folding.

    PubMed

    Mukaiyama, Atsushi; Nakamura, Takashi; Makabe, Koki; Maki, Kosuke; Goto, Yuji; Kuwajima, Kunihiro

    2013-01-23

    The acid transition of β(2)-microglobulin (β2m) was studied by tryptophan fluorescence, peptide circular dichroism, and NMR spectroscopy. The protein exhibits a three-state transition with an equilibrium intermediate accumulated at pH4 (25°C). The pH4 intermediate has typical characteristics of the molten globule (MG) state; it showed a native-like secondary structure without specific side-chain tertiary structure, and the hydrodynamic radius determined by pulse field gradient NMR was only 20% larger than that of the native state. The accumulation of the pH4 intermediate is very analogous to the behavior of apomyoglobin, for which the pH4 MG has been well characterized, although β2m, a β-protein, is structurally very different from α-helical apomyoglobin. NMR pH titration of histidine residues of β2m has also indicated that His84 has an abnormally low pK(a) value in the native state. From the pH dependence of the unfolding transition, the protonations of this histidine and 10 weakly abnormal carboxylates triggered the transition from the native to the MG state. This behavior is again analogous to that of apomyoglobin, suggesting a common mechanism of production of the pH4 MG. In contrast to the folding of apomyoglobin, in which the MG was equivalent to the burst-phase kinetic folding intermediate, the burst-phase refolding intermediate of β2m, detected by stopped-flow circular dichroism, was significantly more structured than the pH4 intermediate. It is proposed that the folding of β2m from its acid-denatured state takes place in the following order: denatured state→MG→burst-phase intermediate→native state. PMID:23154171

  2. Vibrational coherence from van der Waals modes in the native and molten-globule states of ZnII-substituted cytochrome c.

    PubMed

    Dillman, Kevin L; Beck, Warren F

    2011-07-01

    The low-frequency vibrational coherence from Zn(II)-substituted cytochrome c (ZnCytc) was characterized at room temperature in the native and acid/high-salt molten-globule states using femtosecond pump-probe, dynamic-absorption spectroscopy and impulsive excitation of the Soret absorption band. The pump-probe signals observed from the native state contain two types of modulation components in the vibrational coherence. The first type is a set of slowly damped (damping time γ > 1.5 ps) components with frequencies of 10, 30, 70, and 120 cm(-1) that are assigned to out-of-plane vibrations of the porphyrin macrocycle following similar assignments in other porphyrin systems. A similar set of components is observed in the pump-probe signal from the molten-globule state, but the signal is much less strongly modulated. The second type is a strong, very rapidly damped (γ < 150 fs) 79 cm(-1) modulation component that is assigned to van der Waals interactions between the porphyrin and nonpolar groups in its first solvation shell from the surrounding protein structure; the line shape and intensity of this component are comparable to those observed previously for bacteriochlorophyll a and Zn(II)meso-tetrakis(N-methylpyridyl)porphyrin in solution. This component is almost completely absent from the signal from the molten-globule state. The results suggest that the van der Waals modes obtain intensity enhancement in the vibrational coherence because the attacking groups are displaced by the change of extent and/or change in shape of the π-electron density that accompanies the π → π* optical transition of the Zn(II) porphyrin. In the molten-globule state of ZnCytc, owing to the expanded hydrophobic core and to the loss of order for the groups that attack the π-electron density of the Zn(II) porphyrin, the van der Waals modes are rendered effectively inactive. These results support an assignment of the broad low-frequency background in the spectrum of the vibrational

  3. Heterogeneity of equilibrium molten globule state of cytochrome c induced by weak salt denaturants under physiological condition.

    PubMed

    Rahaman, Hamidur; Alam Khan, Md Khurshid; Hassan, Md Imtaiyaz; Islam, Asimul; Moosavi-Movahedi, Ali Akbar; Ahmad, Faizan

    2015-01-01

    While many proteins are recognized to undergo folding via intermediate(s), the heterogeneity of equilibrium folding intermediate(s) along the folding pathway is less understood. In our present study, FTIR spectroscopy, far- and near-UV circular dichroism (CD), ANS and tryptophan fluorescence, near IR absorbance spectroscopy and dynamic light scattering (DLS) were used to study the structural and thermodynamic characteristics of the native (N), denatured (D) and intermediate state (X) of goat cytochorme c (cyt-c) induced by weak salt denaturants (LiBr, LiCl and LiClO4) at pH 6.0 and 25°C. The LiBr-induced denaturation of cyt-c measured by Soret absorption (Δε400) and CD ([θ]409), is a three-step process, N ↔ X ↔ D. It is observed that the X state obtained along the denaturation pathway of cyt-c possesses common structural and thermodynamic characteristics of the molten globule (MG) state. The MG state of cyt-c induced by LiBr is compared for its structural and thermodynamic parameters with those found in other solvent conditions such as LiCl, LiClO4 and acidic pH. Our observations suggest: (1) that the LiBr-induced MG state of cyt-c retains the native Met80-Fe(III) axial bond and Trp59-propionate interactions; (2) that LiBr-induced MG state of cyt-c is more compact retaining the hydrophobic interactions in comparison to the MG states induced by LiCl, LiClO4 and 0.5 M NaCl at pH 2.0; and (3) that there exists heterogeneity of equilibrium intermediates along the unfolding pathway of cyt-c as highly ordered (X1), classical (X2) and disordered (X3), i.e., D ↔ X3 ↔ X2 ↔ X1 ↔ N.

  4. Heterogeneity of Equilibrium Molten Globule State of Cytochrome c Induced by Weak Salt Denaturants under Physiological Condition

    PubMed Central

    Rahaman, Hamidur; Alam Khan, Md. Khurshid; Hassan, Md. Imtaiyaz; Islam, Asimul; Moosavi-Movahedi, Ali Akbar; Ahmad, Faizan

    2015-01-01

    While many proteins are recognized to undergo folding via intermediate(s), the heterogeneity of equilibrium folding intermediate(s) along the folding pathway is less understood. In our present study, FTIR spectroscopy, far- and near-UV circular dichroism (CD), ANS and tryptophan fluorescence, near IR absorbance spectroscopy and dynamic light scattering (DLS) were used to study the structural and thermodynamic characteristics of the native (N), denatured (D) and intermediate state (X) of goat cytochorme c (cyt-c) induced by weak salt denaturants (LiBr, LiCl and LiClO4) at pH 6.0 and 25°C. The LiBr-induced denaturation of cyt-c measured by Soret absorption (Δε400) and CD ([θ]409), is a three-step process, N ↔ X ↔ D. It is observed that the X state obtained along the denaturation pathway of cyt-c possesses common structural and thermodynamic characteristics of the molten globule (MG) state. The MG state of cyt-c induced by LiBr is compared for its structural and thermodynamic parameters with those found in other solvent conditions such as LiCl, LiClO4 and acidic pH. Our observations suggest: (1) that the LiBr-induced MG state of cyt-c retains the native Met80-Fe(III) axial bond and Trp59-propionate interactions; (2) that LiBr-induced MG state of cyt-c is more compact retaining the hydrophobic interactions in comparison to the MG states induced by LiCl, LiClO4 and 0.5 M NaCl at pH 2.0; and (3) that there exists heterogeneity of equilibrium intermediates along the unfolding pathway of cyt-c as highly ordered (X1), classical (X2) and disordered (X3), i.e., D ↔ X3 ↔ X2 ↔ X1 ↔ N. PMID:25849212

  5. Heterogeneity of equilibrium molten globule state of cytochrome c induced by weak salt denaturants under physiological condition.

    PubMed

    Rahaman, Hamidur; Alam Khan, Md Khurshid; Hassan, Md Imtaiyaz; Islam, Asimul; Moosavi-Movahedi, Ali Akbar; Ahmad, Faizan

    2015-01-01

    While many proteins are recognized to undergo folding via intermediate(s), the heterogeneity of equilibrium folding intermediate(s) along the folding pathway is less understood. In our present study, FTIR spectroscopy, far- and near-UV circular dichroism (CD), ANS and tryptophan fluorescence, near IR absorbance spectroscopy and dynamic light scattering (DLS) were used to study the structural and thermodynamic characteristics of the native (N), denatured (D) and intermediate state (X) of goat cytochorme c (cyt-c) induced by weak salt denaturants (LiBr, LiCl and LiClO4) at pH 6.0 and 25°C. The LiBr-induced denaturation of cyt-c measured by Soret absorption (Δε400) and CD ([θ]409), is a three-step process, N ↔ X ↔ D. It is observed that the X state obtained along the denaturation pathway of cyt-c possesses common structural and thermodynamic characteristics of the molten globule (MG) state. The MG state of cyt-c induced by LiBr is compared for its structural and thermodynamic parameters with those found in other solvent conditions such as LiCl, LiClO4 and acidic pH. Our observations suggest: (1) that the LiBr-induced MG state of cyt-c retains the native Met80-Fe(III) axial bond and Trp59-propionate interactions; (2) that LiBr-induced MG state of cyt-c is more compact retaining the hydrophobic interactions in comparison to the MG states induced by LiCl, LiClO4 and 0.5 M NaCl at pH 2.0; and (3) that there exists heterogeneity of equilibrium intermediates along the unfolding pathway of cyt-c as highly ordered (X1), classical (X2) and disordered (X3), i.e., D ↔ X3 ↔ X2 ↔ X1 ↔ N. PMID:25849212

  6. Characterization of pre-molten globule state of yeast iso-1-cytochrome c and its deletants at pH 6.0 and 25 °C.

    PubMed

    Haque, Md Anzarul; Ubaid-Ullah, Shah; Zaidi, Sobia; Hassan, Md Imtaiyaz; Islam, Asimul; Batra, Janendra K; Ahmad, Faizan

    2015-01-01

    To understand the role of five extra N-terminal residues, we prepared wild type (WT) yeast iso-1-cytochrome c (y-cyt-c) and its deletants by subsequently deleting these residues. Denaturation of all these proteins induced by LiCl was followed by observing changes in molar absorption coefficient at 405 nm (Δɛ405), the mean residue ellipticity at 222 nm ([θ]222), and the difference mean residue ellipticity at 409 nm (Δ[θ]409) near physiological pH and temperature (pH 6.0 and 25 °C). It was observed that in each case LiCl induces biphasic transition, N (native) state ↔ X (intermediate) state ↔ D (denatured) state. The intermediate (X) was characterized by the far-UV, near-UV and Soret circular dichroism, ANS (8-anilino-1-naphthalenesulfonic acid) binding and dynamic light scattering measurements. These measurements led us to conclude that X state of each protein has structural characteristics of PMG (pre-molten globule) state. Thermodynamic stability of all proteins was also determined. It was observed that the N-terminal extension stabilizes the native WT protein but it has no effect on the stability of PMG state. Another state was observed for each protein, in the presence of 0.33 M Na2SO4 at pH 2.1, which when characterized showed all structural characteristics of MG (molten globule) state. PMID:25450045

  7. Independent of their localization in protein the hydrophobic amino acid residues have no effect on the molten globule state of apomyoglobin and the disulfide bond on the surface of apomyoglobin stabilizes this intermediate state.

    PubMed

    Melnik, Tatiana N; Majorina, Maria A; Larina, Daria S; Kashparov, Ivan A; Samatova, Ekaterina N; Glukhov, Anatoly S; Melnik, Bogdan S

    2014-01-01

    At present it is unclear which interactions in proteins reveal the presence of intermediate states, their stability and formation rate. In this study, we have investigated the effect of substitutions of hydrophobic amino acid residues in the hydrophobic core of protein and on its surface on a molten globule type intermediate state of apomyoglobin. It has been found that independent of their localization in protein, substitutions of hydrophobic amino acid residues do not affect the stability of the molten globule state of apomyoglobin. It has been shown also that introduction of a disulfide bond on the protein surface can stabilize the molten globule state. However in the case of apomyoglobin, stabilization of the intermediate state leads to relative destabilization of the native state of apomyoglobin. The result obtained allows us not only to conclude which mutations can have an effect on the intermediate state of the molten globule type, but also explains why the introduction of a disulfide bond (which seems to "strengthen" the protein) can result in destabilization of the protein native state of apomyoglobin. PMID:24892675

  8. Interaction of insulin with methyl tert-butyl ether promotes molten globule-like state and production of reactive oxygen species.

    PubMed

    Valipour, Masoumeh; Maghami, Parvaneh; Habibi-Rezaei, Mehran; Sadeghpour, Mostafa; Khademian, Mohamad Ali; Mosavi, Khadijeh; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

    2015-09-01

    Interaction of methyl tert-butyl ether (MTBE) with proteins is a new look at its potential adverse biological effects. When MTBE is released to the environment it enters the blood stream through inhalation, and could affect the properties of various proteins. Here we investigated the interaction of MTBE with insulin and its effect on insulin structural changes. Our results showed that insulin formed a molten globule (MG)-like structure in the presence of 8 μM MTBE under physiological pH. The insulin structural changes were studied using spectroscopy methods, viscosity calculation, dynamic light scattering and differential scanning calorimetry. To delineate the mechanisms involved in MTBE-protein interactions, the formation of reactive oxygen specious (ROS) and formation of protein aggregates were measured. The chemiluminscence experiments revealed an increase in ROS production in the presence of MTBE especially in the MG-like state. These results were further confirmed by the aggregation tests, which indicated more aggregation of insulin at 40 μM MTBE compared with 8 μM. Thus, the formation of initial aggregates and exposure of the hydrophobic patches upon formation of the MG-like state in the presence of MTBE drives protein oxidation and ROS generation.

  9. The Pathogenic Mutation T182A Converts the Prion Protein into a Molten Globule-like Conformation Whose Misfolding to Oligomers but Not to Fibrils Is Drastically Accelerated.

    PubMed

    Singh, Jogender; Udgaonkar, Jayant B

    2016-01-26

    Delineation of the effects of pathogenic mutations linked with familial prion diseases on the structure and misfolding of prion protein (PrP) will be useful in understanding the molecular mechanism of PrP misfolding. Here, it has been shown that the pathogenic mutation T182A causes a drastic reduction in the apparent cooperativity and enthalpy of unfolding of the mouse prion protein (moPrP) under misfolding-prone conditions by converting the protein into a molten globule (MG)-like conformation. Hydrogen-deuterium exchange studies in conjunction with mass spectrometry indicate that the T182A mutation disrupts the core of the protein, thereby increasing overall structural dynamics. T182A moPrP is shown to misfold to oligomers very much faster than does wild-type (wt) moPrP but to misfold to fibrils at a rate similar to that of wt moPrP. This observation suggests that oligomers are unlikely to play a productive role in the direct pathway of aggregation from monomer to fibrils. The observation that fully folded T182A moPrP has a MG-like structure, and that it misfolds to oligomers much faster than does wt moPrP, suggests that a MG-like intermediate, whose structure resembles that of fully folded T182A moPrP, might be populated early on the pathway of misfolding of wt moPrP to oligomers. PMID:26713717

  10. Evidence for Dry Molten Globule-Like Domains in the pH-Induced Equilibrium Folding Intermediate of a Multidomain Protein.

    PubMed

    Acharya, Nirbhik; Mishra, Prajna; Jha, Santosh Kumar

    2016-01-01

    The role of van der Waals (vdW) packing interactions compared to the hydrophobic effect in stabilizing the functional structure of proteins is poorly understood. Here we show, using fluorescence resonance energy transfer, dynamic fluorescence quenching, red-edge excitation shift, and near- and far-UV circular dichroism, that the pH-induced structural perturbation of a multidomain protein leads to the formation of a state in which two out of the three domains have characteristics of dry molten globules, that is, the domains are expanded compared to the native protein with disrupted packing interactions but have dry cores. We quantitatively estimate the energetic contribution of vdW interactions and show that they play an important role in the stability of the native state and cooperativity of its structural transition, in addition to the hydrophobic effect. Our results also indicate that during the pH-induced unfolding, side-chain unlocking and hydrophobic solvation occur in two distinct steps and not in a concerted manner, as commonly believed. PMID:26700266

  11. Molten globule-like partially folded state of Bacillus licheniformis α-amylase at low pH induced by 1,1,1,3,3,3-hexafluoroisopropanol.

    PubMed

    Abd Halim, Adyani Azizah; Zaroog, Mohammed Suleiman; Kadir, Habsah Abdul; Tayyab, Saad

    2014-01-01

    Effect of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) on acid-denatured Bacillus licheniformis α -amylase (BLA) at pH 2.0 was investigated by far-UV CD, intrinsic fluorescence, and ANS fluorescence measurements. Addition of increasing HFIP concentrations led to an increase in the mean residue ellipticity at 222 nm (MRE 222 nm) up to 1.5 M HFIP concentration beyond which it sloped off. A small increase in the intrinsic fluorescence and a marked increase in the ANS fluorescence were also observed up to 0.4 M HFIP concentration, both of which decreased thereafter. Far- and near-UV CD spectra of the HFIP-induced state observed at 0.4 M HFIP showed significant retention of the secondary structures closer to native BLA but a disordered tertiary structure. Increase in the ANS fluorescence intensity was also observed with the HFIP-induced state, suggesting exposure of the hydrophobic clusters to the solvent. Furthermore, thermal denaturation of HFIP-induced state showed a non-cooperative transition. Taken together, all these results suggested that HFIP-induced state of BLA represented a molten globule-like state at pH 2.0. PMID:24977228

  12. Mechanistic Insight into the Reactivation of BCAII Enzyme from Denatured and Molten Globule States by Eukaryotic Ribosomes and Domain V rRNAs

    PubMed Central

    Chakraborty, Biprashekhar; Bhakta, Sayan; Sengupta, Jayati

    2016-01-01

    In all life forms, decoding of messenger-RNA into polypeptide chain is accomplished by the ribosome. Several protein chaperones are known to bind at the exit of ribosomal tunnel to ensure proper folding of the nascent chain by inhibiting their premature folding in the densely crowded environment of the cell. However, accumulating evidence suggests that ribosome may play a chaperone role in protein folding events in vitro. Ribosome-mediated folding of denatured proteins by prokaryotic ribosomes has been studied extensively. The RNA-assisted chaperone activity of the prokaryotic ribosome has been attributed to the domain V, a span of 23S rRNA at the intersubunit side of the large subunit encompassing the Peptidyl Transferase Centre. Evidently, this functional property of ribosome is unrelated to the nascent chain protein folding at the exit of the ribosomal tunnel. Here, we seek to scrutinize whether this unique function is conserved in a primitive kinetoplastid group of eukaryotic species Leishmania donovani where the ribosome structure possesses distinct additional features and appears markedly different compared to other higher eukaryotic ribosomes. Bovine Carbonic Anhydrase II (BCAII) enzyme was considered as the model protein. Our results manifest that domain V of the large subunit rRNA of Leishmania ribosomes preserves chaperone activity suggesting that ribosome-mediated protein folding is, indeed, a conserved phenomenon. Further, we aimed to investigate the mechanism underpinning the ribosome-assisted protein reactivation process. Interestingly, the surface plasmon resonance binding analyses exhibit that rRNA guides productive folding by directly interacting with molten globule-like states of the protein. In contrast, native protein shows no notable affinity to the rRNA. Thus, our study not only confirms conserved, RNA-mediated chaperoning role of ribosome but also provides crucial insight into the mechanism of the process. PMID:27099964

  13. Mechanistic Insight into the Reactivation of BCAII Enzyme from Denatured and Molten Globule States by Eukaryotic Ribosomes and Domain V rRNAs.

    PubMed

    Chakraborty, Biprashekhar; Bhakta, Sayan; Sengupta, Jayati

    2016-01-01

    In all life forms, decoding of messenger-RNA into polypeptide chain is accomplished by the ribosome. Several protein chaperones are known to bind at the exit of ribosomal tunnel to ensure proper folding of the nascent chain by inhibiting their premature folding in the densely crowded environment of the cell. However, accumulating evidence suggests that ribosome may play a chaperone role in protein folding events in vitro. Ribosome-mediated folding of denatured proteins by prokaryotic ribosomes has been studied extensively. The RNA-assisted chaperone activity of the prokaryotic ribosome has been attributed to the domain V, a span of 23S rRNA at the intersubunit side of the large subunit encompassing the Peptidyl Transferase Centre. Evidently, this functional property of ribosome is unrelated to the nascent chain protein folding at the exit of the ribosomal tunnel. Here, we seek to scrutinize whether this unique function is conserved in a primitive kinetoplastid group of eukaryotic species Leishmania donovani where the ribosome structure possesses distinct additional features and appears markedly different compared to other higher eukaryotic ribosomes. Bovine Carbonic Anhydrase II (BCAII) enzyme was considered as the model protein. Our results manifest that domain V of the large subunit rRNA of Leishmania ribosomes preserves chaperone activity suggesting that ribosome-mediated protein folding is, indeed, a conserved phenomenon. Further, we aimed to investigate the mechanism underpinning the ribosome-assisted protein reactivation process. Interestingly, the surface plasmon resonance binding analyses exhibit that rRNA guides productive folding by directly interacting with molten globule-like states of the protein. In contrast, native protein shows no notable affinity to the rRNA. Thus, our study not only confirms conserved, RNA-mediated chaperoning role of ribosome but also provides crucial insight into the mechanism of the process. PMID:27099964

  14. Mechanistic Insight into the Reactivation of BCAII Enzyme from Denatured and Molten Globule States by Eukaryotic Ribosomes and Domain V rRNAs.

    PubMed

    Chakraborty, Biprashekhar; Bhakta, Sayan; Sengupta, Jayati

    2016-01-01

    In all life forms, decoding of messenger-RNA into polypeptide chain is accomplished by the ribosome. Several protein chaperones are known to bind at the exit of ribosomal tunnel to ensure proper folding of the nascent chain by inhibiting their premature folding in the densely crowded environment of the cell. However, accumulating evidence suggests that ribosome may play a chaperone role in protein folding events in vitro. Ribosome-mediated folding of denatured proteins by prokaryotic ribosomes has been studied extensively. The RNA-assisted chaperone activity of the prokaryotic ribosome has been attributed to the domain V, a span of 23S rRNA at the intersubunit side of the large subunit encompassing the Peptidyl Transferase Centre. Evidently, this functional property of ribosome is unrelated to the nascent chain protein folding at the exit of the ribosomal tunnel. Here, we seek to scrutinize whether this unique function is conserved in a primitive kinetoplastid group of eukaryotic species Leishmania donovani where the ribosome structure possesses distinct additional features and appears markedly different compared to other higher eukaryotic ribosomes. Bovine Carbonic Anhydrase II (BCAII) enzyme was considered as the model protein. Our results manifest that domain V of the large subunit rRNA of Leishmania ribosomes preserves chaperone activity suggesting that ribosome-mediated protein folding is, indeed, a conserved phenomenon. Further, we aimed to investigate the mechanism underpinning the ribosome-assisted protein reactivation process. Interestingly, the surface plasmon resonance binding analyses exhibit that rRNA guides productive folding by directly interacting with molten globule-like states of the protein. In contrast, native protein shows no notable affinity to the rRNA. Thus, our study not only confirms conserved, RNA-mediated chaperoning role of ribosome but also provides crucial insight into the mechanism of the process.

  15. Role of ionic liquid on the conformational dynamics in the native, molten globule, and unfolded states of cytochrome c: a fluorescence correlation spectroscopy study.

    PubMed

    Sen Mojumdar, Supratik; Chowdhury, Rajdeep; Chattoraj, Shyamtanu; Bhattacharyya, Kankan

    2012-10-11

    The role of a room temperature ionic liquid (RTIL, [pmim][Br]) on the size and conformational dynamics of a protein, horse heart cytochrome c (Cyt C) in its native, molten globule (MG-I and II), and unfolded states is studied using fluorescence correlation spectroscopy (FCS). For this purpose, the protein was covalently labeled by a fluorescent dye, Alexa Fluor 488. It is observed that the addition of the RTIL leads to an increase in the hydrodynamic radius (r(H)) of the protein, Cyt C in the native or MG-I state. In contrast, the addition of RTIL causes a decrease in the size (hydrodynamic radius, r(H)) of Cyt C unfolded by GdnHCl or MG-II state. The decrease in size indicates the formation of a relatively compact structure. We detected two types of conformational relaxation of the protein. The shorter relaxation time component (~3-5.5 μs) corresponds to the protein folding or intrachain contact formation, while the relatively longer time component (~63-122 μs) may be assigned to the motion of the protein side chains or concerted chain dynamics. The burst integrated fluorescence lifetime histograms indicate that the increase in size of the protein is accompanied by an increase in the contribution of the shorter component (~0.3-0.4 ns) with a concomitant decrease of the contribution of the longer component (~2.8-3.6 ns). An opposite trend is observed during the decrease in size of the protein. PMID:22989328

  16. Thackeray's Globules

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Strangely glowing, floating dark clouds are silhouetted against nearby bright stars in a busy star-forming region viewed by NASA's Hubble Space Telescope.

    The image showing dense, opaque dust clouds - known as globules - in the star-forming region IC 2944 is available online at http://heritage.stsci.edu or http://oposite.stsci.edu/pubinfo/pr/2002/01 or http://www.jpl.nasa.gov/images/wfpc . It was taken by Hubble's Wide Field and Planetary Camera 2, designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif.

    Little is known about the origin and nature of these globules in IC 2944, which were first found by astronomer A.D. Thackeray in 1950. Globules are generally associated with large hydrogen-emitting star-formation regions, which give off the glowing light of hydrogen gas.

    The largest globule in this image consists of two separate clouds that gently overlap along our line of sight. Each cloud is nearly 1.4 light-years along its longest dimension. Collectively, they contain enough material to equal more than 15 times the mass of our Sun. The surrounding hydrogen-rich region, IC 2944, is filled with gas and dust illuminated and heated by a loose cluster of stars that are much hotter and more massive than our Sun. IC 2944 is relatively close by, only 5,900 light-years away in the constellation Centaurus.

    Using the remarkable resolution of Hubble, astronomers can for the first time study the intricate structure of these globules. They appear to be heavily fractured, as if major forces were tearing them apart. When radio astronomers observed the faint hiss of molecules within the globules, they realized that the globules are actually in constant, churning motion, moving supersonically among each other. This may be caused by powerful ultraviolet radiation from the luminous, massive stars, which heat up hydrogen gas in the region. The gas expands and streams against the globules, leading to their destruction. Despite their serene appearance

  17. Partial phase diagram of aqueous bovine carbonic anhydrase: analyses of the pressure-dependent temperatures of the low- to physiological-temperature nondenaturational conformational change and of unfolding to the molten globule state.

    PubMed

    McNevin, Stacey L; Nguyen, Duong T; Britt, B Mark

    2008-10-01

    At 1.0 atm pressure and in 150 mM sodium phosphate (pH=7.0), bovine carbonic anhydrase undergoes a nondenaturational conformational change at 30.3 degrees C and an unfolding transition from the physiological conformer to the molten globule state at 67.4 degrees C. The pressure dependences of the temperatures of these transitions have been studied under reversible conditions for the purpose of understanding DeltaH degrees, DeltaS degrees, and DeltaV for each conformational change. Temperatures for the low-temperature to physiological-temperature conformational change TL-->P are obtained from physiologically relevant conditions using slow-scan-rate differential scanning calorimetry. Temperatures for the physiological-temperature conformation to molten globule state conversion TP-->MG are obtained from differential scanning calorimetry measurements of the apparent transition temperature in the presence of guanidine hydrochloride extrapolated to zero molar denaturant. The use of slow-scan-rate differential scanning calorimetry permits the calculation of the activation volume for the conversion of the low-temperature conformer to the physiological-temperature conformer DeltaVL-->P. At 1.0 atm pressure, the transition from the low-temperature conformer to the physiological-temperature conformer involves a volume change DeltaVL-->P=15+/-2 L/mole, which contrasts with the partial unfolding of the physiological-temperature conformer to the molten globule state (DeltaVP-->MG=26+/-9 L/mole). The activation volume for this process DeltaVL-->P=51+/-9 L/mole and is consistent with a prior thermodynamic analysis that suggests the conformational transition from the low-temperature conformation to the physiological-temperature conformation possesses a substantial unfolding quality. These results provide further evidence the structure of the enzyme obtained from crystals grown below 30 degrees C should not be regarded as the physiological structure (the normal bovine body

  18. Effect of coil-globule transition on the single-chain crystallization.

    PubMed

    Wang, Mao-Xiang

    2013-05-30

    The folding process of a single chain including coil-globule transition and crystallization has been investigated through dynamic Monte Carlo simulations. The results based upon ensemble averaging illustrated three distinct states: coil, molten globule, and globule states. Furthermore, the crystallization process from these collapsed states demonstrated various characteristics and it also verified the thermodynamic partitions. The isothermal crystallization in the three states showed the folding rates, and the final crystallite morphologies strongly depended on the collapsed states. Especially, the onset temperature of crystallization in the intermediate molten globule state demonstrated the strongest sensitivity to the solvent qualities in the three different states. Moreover, the crystallization in this intermediate state illustrated a two-step folding mechanism with the prior dense core serving as a precursor to induce the subsequent crystallization. Our observations would help in understanding the thermodynamics and kinetics of phase transition of a single macromolecule. Possible relations to the protein folding were also discussed. PMID:23646890

  19. Radial systems of dark globules

    SciTech Connect

    Gyul'budagyn, A.L.

    1986-03-01

    The author gives examples of radial systems consisting of dark globules and ''elephant trunks''. Besides already known systems, which contain hot stars at their center, data are given on three radial systems of a new kind, at the center of which there are stars of spectral types later than B. Data are given on 32 globules of radial systems of the association Cep OB2. On the basis of the observational data, it is concluded that at least some of the isolated Bok globules derive from elephant trunks and dark globules forming radial systems around hot stars. It is also suggested that the two molecular clouds situated near the Rosette nebula and possessing velocities differing by ca 20 km/sec from the velocity of the nebula could have been ejected in opposite directions from the center of the nebula. One of these clouds consists of dark globules forming the radial system of the Rosette nebula.

  20. Anomalous Diffusion in Fractal Globules

    NASA Astrophysics Data System (ADS)

    Tamm, M. V.; Nazarov, L. I.; Gavrilov, A. A.; Chertovich, A. V.

    2015-05-01

    The fractal globule state is a popular model for describing chromatin packing in eukaryotic nuclei. Here we provide a scaling theory and dissipative particle dynamics computer simulation for the thermal motion of monomers in the fractal globule state. Simulations starting from different entanglement-free initial states show good convergence which provides evidence supporting the existence of a unique metastable fractal globule state. We show monomer motion in this state to be subdiffusive described by ⟨X2(t )⟩˜tαF with αF close to 0.4. This result is in good agreement with existing experimental data on the chromatin dynamics, which makes an additional argument in support of the fractal globule model of chromatin packing.

  1. Anomalous diffusion in fractal globules.

    PubMed

    Tamm, M V; Nazarov, L I; Gavrilov, A A; Chertovich, A V

    2015-05-01

    The fractal globule state is a popular model for describing chromatin packing in eukaryotic nuclei. Here we provide a scaling theory and dissipative particle dynamics computer simulation for the thermal motion of monomers in the fractal globule state. Simulations starting from different entanglement-free initial states show good convergence which provides evidence supporting the existence of a unique metastable fractal globule state. We show monomer motion in this state to be subdiffusive described by ⟨X(2)(t)⟩∼t(αF) with αF close to 0.4. This result is in good agreement with existing experimental data on the chromatin dynamics, which makes an additional argument in support of the fractal globule model of chromatin packing. PMID:25978267

  2. Anomalous diffusion in fractal globules.

    PubMed

    Tamm, M V; Nazarov, L I; Gavrilov, A A; Chertovich, A V

    2015-05-01

    The fractal globule state is a popular model for describing chromatin packing in eukaryotic nuclei. Here we provide a scaling theory and dissipative particle dynamics computer simulation for the thermal motion of monomers in the fractal globule state. Simulations starting from different entanglement-free initial states show good convergence which provides evidence supporting the existence of a unique metastable fractal globule state. We show monomer motion in this state to be subdiffusive described by ⟨X(2)(t)⟩∼t(αF) with αF close to 0.4. This result is in good agreement with existing experimental data on the chromatin dynamics, which makes an additional argument in support of the fractal globule model of chromatin packing.

  3. The numerical analysis of the rotational theory for the formation of lunar globules

    NASA Technical Reports Server (NTRS)

    Ross, J.; Bastin, J.; Stewart, K.

    1982-01-01

    The morphology of lunar globules is studied through the application of a numerical analysis of their rotation in space during cooling. It is assumed that molten rock is shot from the surface of the moon, solidifies in space above the moon and then falls back to the surface. The rotational theory studied makes the following assumptions: the volume of the molten rock does not change during cooling; the angular momentum is conserved; there are no internal motions because of the high viscosity of the molten rock, i.e., in equilibrium the globule is rotating as a rigid body; finally, the kinetic reaction of the globule to the forces is fast relative to the rate of cooling, i.e., the globule reaches equilibrium at constant energy. These assumptions are subjected to numerical analysis yielding good agreement between the actual globule shapes and the numerical results, but leaving some doubt as to the validity of the rotational theory due to the failure to establish the existence of true local minima and an incomplete understanding of the thermokentics.

  4. Thackeray's Globules in IC 2944

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Strangely glowing dark clouds float serenely in this remarkable and beautiful image taken with NASA's Hubble Space Telescope. These dense, opaque dust clouds - known as 'globules' - are silhouetted against nearby bright stars in the busy star-forming region, IC 2944. These globules were first found in IC 2944 by astronomer A.D. Thackeray in 1950. Although globules like these have been known since Dutch-American astronomer Bart Bok first drew attention to such objects in 1947, little is still known about their origin and nature, except that they are generally associated with areas of star formation, called 'HII regions' due to the presence of hydrogen gas. The largest of the globules in this image is actually two separate clouds that gently overlap along our line of sight. Each cloud is nearly 1.4 light-years (50 arcseconds) along its longest dimension, and collectively, they contain enough material to equal over 15 solar masses. IC 2944, the surrounding HII region, is filled with gas and dust that is illuminated and heated by a loose cluster of O-type stars. These stars are much hotter and much more massive than our Sun. IC 2944 is relatively close by, located only 5900 light-years (1800 parsecs) away in the constellation Centaurus. Thanks to the remarkable resolution offered by the Hubble Space Telescope, astronomers can for the first time study the intricate structure of these globules. The globules appear to be heavily fractured, as if major forces were tearing them apart. When radio astronomers observed the faint hiss of molecules within the globules, they realized that the globules are actually in constant, churning motion, moving supersonically among each other. This may be caused by the powerful ultraviolet radiation from the luminous, massive stars, which also heat up the gas in the HII region, causing it to expand and stream against the globules, leading to their destruction. Despite their serene appearance, the globules may actually be likened to clumps

  5. Formation of Metal and Silicate Globules in Gujba: A New Bencubbin-like Meteorite Fall

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Kallemeyn, Gregory W.; Wasson, John T.; Clayton, Robert N.; Mayeda, Toshiko; Grady, Monica; Verchovsky, Alexander B.; Eugster, Otto; Lorenzetti, Silvio

    2006-01-01

    Gujba is a coarse-grained meteorite fall composed of 41 vol% large kamacite globules, 20 vol% large light-colored silicate globules with cryptocrystalline, barred pyroxene and barred olivine textures, 39 vol% dark-colored, silicate-rich matrix, and rare refractory inclusions. Gujba resembles Bencubbin and Weatherford in texture, oxygen-isotopic composition and in having high bulk delta N-15 values (approximately +685%0). The He-3 cosmic-ray exposure age of Gujba (26 +/- 7 Ma) is essentially identical to that of Bencubbin, suggesting that they were both reduced to meter-size fragments in the same parent-body collision. The Gujba metal globules exhibit metal-troilite quench textures and vary in their abundances of troilite and volatile siderophile elements. We suggest that the metal globules formed as liquid droplets either via condensation in an impact-generated vapor plume or by evaporation of preexisting metal particles in a plume. The lower the abundance of volatile elements in the metal globules, the higher the globule quench temperature. We infer that the large silicate globules also formed from completely molten droplets; their low volatile-element abundances indicate that they also formed at high temperatures, probably by processes analogous to those that formed the metal globules. The coarse-grained Bencubbin-Weatherford-Gujba meteorites may represent a depositional component from the vapor cloud enriched in coarse and dense particles. A second class of Bencubbin-like meteorites (represented by Hammadah a1 Hamra 237 and QUE 94411) may be a finer fraction derived from the same vapor cloud

  6. Presolar Organic Globules in Astromaterials

    NASA Technical Reports Server (NTRS)

    Nakamura-Messenger, K.; Messenger, S.; Keller, L. P.; Clemett, S. J.

    2012-01-01

    Presolar grains were identified in meteorite residues 20 years ago based on their exotic isotopic compositions [1]. Their study has provide new insights into stellar evolution and the first view of the original building blocks of the solar system. Organic matter in meteorites and IDPs is highly enriched in D/H and N-15/N-14 at micron scales, possibly due to presolar organic grains [2-4]. These anomalies are ascribed to the partial preservation of presolar cold molecular cloud material. Identifying the carriers of these anomalies and elucidating their physical and chemical properties may give new views of interstellar chemistry and better understanding of the original components of the protosolar disk. However, identifying the carriers has been hampered by their small size and the inability to chemically isolate them. Thanks to major advances in nano-scale analytical techniques and advanced sample preparation, we were able to show that in the Tagish Lake meteorite, the principle carriers of these isotopic anomalies are sub-microns, hollow organic globules [5]. The organic globules likely formed by photochemical processing of organic ices in a cold molecular cloud or the outermost regions of the protosolar disk [5]. Organic globules with similar physical, chemical, and isotopic properties are also recently found from Bells CM2 carbonaceous chondrite, in IDPs [6] and in the comet Wild-2 samples returned by Stardust [7]. These results support the view that microscopic organic grains were widespread constituents of the protoplanetary disk. Their exotic isotopic compositions trace their origins to the outermost portions of the protosolar disk or a presolar cold molecular cloud.

  7. Molecular Mechanisms of the Cytotoxicity of Human α-Lactalbumin Made Lethal to Tumor Cells (HAMLET) and Other Protein-Oleic Acid Complexes*

    PubMed Central

    Nakamura, Takashi; Aizawa, Tomoyasu; Kariya, Ryusho; Okada, Seiji; Demura, Makoto; Kawano, Keiichi; Makabe, Koki; Kuwajima, Kunihiro

    2013-01-01

    Although HAMLET (human α-lactalbumin made lethal to tumor cells), a complex formed by human α-lactalbumin and oleic acid, has a unique apoptotic activity for the selective killing of tumor cells, the molecular mechanisms of expression of the HAMLET activity are not well understood. Therefore, we studied the molecular properties of HAMLET and its goat counterpart, GAMLET (goat α-lactalbumin made lethal to tumor cells), by pulse field gradient NMR and 920-MHz two-dimensional NMR techniques. We also examined the expression of HAMLET-like activities of complexes between oleic acid and other proteins that form a stable molten globule state. We observed that both HAMLET and GAMLET at pH 7.5 were heterogeneous, composed of the native protein, the monomeric molten globule-like state, and the oligomeric species. At pH 2.0 and 50 °C, HAMLET and GAMLET appeared in the monomeric state, and we identified the oleic acid-binding site in the complexes by two-dimensional NMR. Rather surprisingly, the binding site thus identified was markedly different between HAMLET and GAMLET. Furthermore, canine milk lysozyme, apo-myoglobin, and β2-microglobulin all formed the HAMLET-like complex with the anti-tumor activity, when the protein was treated with oleic acid under conditions in which their molten globule states were stable. From these results, we conclude that the protein portion of HAMLET, GAMLET, and the other HAMLET-like protein-oleic acid complexes is not the origin of their cytotoxicity to tumor cells and that the protein portion of these complexes plays a role in the delivery of cytotoxic oleic acid molecules into tumor cells across the cell membrane. PMID:23580643

  8. Molecular mechanisms of the cytotoxicity of human α-lactalbumin made lethal to tumor cells (HAMLET) and other protein-oleic acid complexes.

    PubMed

    Nakamura, Takashi; Aizawa, Tomoyasu; Kariya, Ryusho; Okada, Seiji; Demura, Makoto; Kawano, Keiichi; Makabe, Koki; Kuwajima, Kunihiro

    2013-05-17

    Although HAMLET (human α-lactalbumin made lethal to tumor cells), a complex formed by human α-lactalbumin and oleic acid, has a unique apoptotic activity for the selective killing of tumor cells, the molecular mechanisms of expression of the HAMLET activity are not well understood. Therefore, we studied the molecular properties of HAMLET and its goat counterpart, GAMLET (goat α-lactalbumin made lethal to tumor cells), by pulse field gradient NMR and 920-MHz two-dimensional NMR techniques. We also examined the expression of HAMLET-like activities of complexes between oleic acid and other proteins that form a stable molten globule state. We observed that both HAMLET and GAMLET at pH 7.5 were heterogeneous, composed of the native protein, the monomeric molten globule-like state, and the oligomeric species. At pH 2.0 and 50 °C, HAMLET and GAMLET appeared in the monomeric state, and we identified the oleic acid-binding site in the complexes by two-dimensional NMR. Rather surprisingly, the binding site thus identified was markedly different between HAMLET and GAMLET. Furthermore, canine milk lysozyme, apo-myoglobin, and β2-microglobulin all formed the HAMLET-like complex with the anti-tumor activity, when the protein was treated with oleic acid under conditions in which their molten globule states were stable. From these results, we conclude that the protein portion of HAMLET, GAMLET, and the other HAMLET-like protein-oleic acid complexes is not the origin of their cytotoxicity to tumor cells and that the protein portion of these complexes plays a role in the delivery of cytotoxic oleic acid molecules into tumor cells across the cell membrane.

  9. Molecular mechanisms of the cytotoxicity of human α-lactalbumin made lethal to tumor cells (HAMLET) and other protein-oleic acid complexes.

    PubMed

    Nakamura, Takashi; Aizawa, Tomoyasu; Kariya, Ryusho; Okada, Seiji; Demura, Makoto; Kawano, Keiichi; Makabe, Koki; Kuwajima, Kunihiro

    2013-05-17

    Although HAMLET (human α-lactalbumin made lethal to tumor cells), a complex formed by human α-lactalbumin and oleic acid, has a unique apoptotic activity for the selective killing of tumor cells, the molecular mechanisms of expression of the HAMLET activity are not well understood. Therefore, we studied the molecular properties of HAMLET and its goat counterpart, GAMLET (goat α-lactalbumin made lethal to tumor cells), by pulse field gradient NMR and 920-MHz two-dimensional NMR techniques. We also examined the expression of HAMLET-like activities of complexes between oleic acid and other proteins that form a stable molten globule state. We observed that both HAMLET and GAMLET at pH 7.5 were heterogeneous, composed of the native protein, the monomeric molten globule-like state, and the oligomeric species. At pH 2.0 and 50 °C, HAMLET and GAMLET appeared in the monomeric state, and we identified the oleic acid-binding site in the complexes by two-dimensional NMR. Rather surprisingly, the binding site thus identified was markedly different between HAMLET and GAMLET. Furthermore, canine milk lysozyme, apo-myoglobin, and β2-microglobulin all formed the HAMLET-like complex with the anti-tumor activity, when the protein was treated with oleic acid under conditions in which their molten globule states were stable. From these results, we conclude that the protein portion of HAMLET, GAMLET, and the other HAMLET-like protein-oleic acid complexes is not the origin of their cytotoxicity to tumor cells and that the protein portion of these complexes plays a role in the delivery of cytotoxic oleic acid molecules into tumor cells across the cell membrane. PMID:23580643

  10. Oleic acid is a key cytotoxic component of HAMLET-like complexes.

    PubMed

    Permyakov, Sergei E; Knyazeva, Ekaterina L; Khasanova, Leysan M; Fadeev, Roman S; Zhadan, Andrei P; Roche-Hakansson, Hazeline; Håkansson, Anders P; Akatov, Vladimir S; Permyakov, Eugene A

    2012-01-01

    HAMLET is a complex of α-lactalbumin (α-LA) with oleic acid (OA) that selectively kills tumor cells and Streptococcus pneumoniae. To assess the contribution of the proteinaceous component to cytotoxicity of HAMLET, OA complexes with proteins structurally and functionally distinct from α-LA were prepared. Similar to HAMLET, the OA complexes with bovine β-lactoglobulin (bLG) and pike parvalbumin (pPA) (bLG-OA-45 and pPA-OA-45, respectively) induced S. pneumoniae D39 cell death. The activation mechanisms of S. pneumoniae death for these complexes were analogous to those for HAMLET, and the cytotoxicity of the complexes increased with OA content in the preparations. The half-maximal inhibitory concentration for HEp-2 cells linearly decreased with rise in OA content in the preparations, and OA concentration in the preparations causing HEp-2 cell death was close to the cytotoxicity of OA alone. Hence, the cytotoxic action of these complexes against HEp-2 cells is induced mostly by OA. Thermal stabilization of bLG upon association with OA implies that cytotoxicity of bLG-OA-45 complex cannot be ascribed to molten globule-like conformation of the protein component. Overall, the proteinaceous component of HAMLET-like complexes studied is not a prerequisite for their activity; the cytotoxicity of these complexes is mostly due to the action of OA.

  11. Photometric distances to nine dark globules

    NASA Astrophysics Data System (ADS)

    Maheswar, G.; Bhatt, H. C.

    2006-07-01

    Distances to nine dark globules are determined by a method using optical (VRI) and near-infrared (near-IR) (JHK) photometry of stars projected towards the field containing the globules. In this method, we compute intrinsic colour indices of stars projected towards the direction of the globule by dereddening the observed colour indices using various trial values of extinction AV and a standard extinction law. These computed intrinsic colour indices for each star are then compared with the intrinsic colour indices of normal main-sequence stars and a spectral type is assigned to the star for which the computed colour indices best match with the standard intrinsic colour indices. Distances (d) to the stars are determined using the AV and absolute magnitude (MV) corresponding to the spectral types thus obtained. A distance versus extinction plot is made and the distance at which AV undergoes a sharp rise is taken to be the distance to the globule. All the clouds studied in this work are in the distance range 160-400pc. The estimated distances to dark globules LDN 544, LDN 549, LDN 567, LDN 543, LDN 1113, LDN 1031, LDN 1225, LDN 1252 and LDN 1257 are 180 +/- 35, 200 +/- 40, 180 +/- 35, 160 +/- 30, 350 +/- 70, 200 +/- 40, 400 +/- 80, 250 +/- 50 and 250 +/- 50pc, respectively. Using the distances determined, we have estimated the masses of the globules and the far-IR luminosity of the IRAS sources associated with them. The mass of the clouds studied are in the range 10-200Msolar.

  12. Dark Globule in IC 1396 (IRAC)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site] Click on image for larger view of inset

    NASA's Spitzer Space Telescope image of a glowing stellar nursery provides a spectacular contrast to the opaque cloud seen in visible light (inset). The Elephant's Trunk Nebula is an elongated dark globule within the emission nebula IC 1396 in the constellation of Cepheus. Located at a distance of 2,450 light-years, the globule is a condensation of dense gas that is barely surviving the strong ionizing radiation from a nearby massive star. The globule is being compressed by the surrounding ionized gas. The dark globule is seen in silhouette at visible-light wavelengths, backlit by the illumination of a bright star located to the left of the field of view.

    The Spitzer Space Telescope pierces through the obscuration to reveal the birth of new protostars, or embryonic stars, and previously unseen young stars. The infrared image was obtained by Spitzer's infrared array camera. The image is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8.0 microns (red). The filamentary appearance of the globule results from the sculpting effects of competing physical processes. The winds from a massive star, located to the left of the image, produce a dense circular rim comprising the 'head' of the globule and a swept-back tail of gas.

    A pair of young stars (LkHa 349 and LkHa 349c) that formed from the dense gas has cleared a spherical cavity within the globule head. While one of these stars is significantly fainter than the other in the visible-light image, they are of comparable brightness in the infrared Spitzer image. This implies the presence of a thick and dusty disc around LkHa 349c. Such circumstellar discs are the precursors of planetary systems. They are much thicker in the early stages of stellar formation when the placental planet-forming material (gas and dust) is still

  13. Interstellar organic globules in meteorites and comets

    NASA Astrophysics Data System (ADS)

    Messenger, Scott; Nakamura-Messenger, Keiko; Keller, Lindsay

    Organic matter in primitive meteorites and interplanetary dust particles (IDPs) is often enriched in D/H and 15N/14N relative to terrestrial values [1-3] due to preservation of interstellar cold molecular cloud material [1]. Some meteorites and IDPs contain micrometer-size inclusions with extreme H and N isotopic anomalies [2-4], possibly due to preserved primordial organic grains. In the Tagish Lake meteorite the main carriers of these anomalies are sub-micrometer, hollow organic globules [5]. Similar objects have been observed in extracts of other chondritic meteorites, but little is known about their N and H isotopic compositions [6-8]. We have measured the H, C, and N isotopic compositions of organic globules in the Bells CM2 carbonaceous chondrite meteorite, NASA Stardust (comet Wild-2) mission samples, and in ‘cometary' IDPs. High-resolution TEM imaging and EELS show that the globules consist of structurally amorphous carbon lacking long range order or development of graphite-like domains. In almost all cases the organic globules have strong enrichments in D/H and 15N/14N. These isotopic anomalies likely resulted from low temperature ( 10 K) chemical reactions in a cold molecular cloud or at the outer regions of the protosolar nebula. These results show that microscopic organic grains were widespread constituents of the protoplanetary disk. Microscopic organic globules may thus have been a common form of prebiotic organic matter delivered to the early Earth by comets and meteorites. References: [1] Messenger S. and Walker R.M. in Astrophysical Implications of the Laboratory Study of Presolar Materials (1997), p.545. [2] Messenger S. (2000) Nature 404, 968. [3] Busemann H. et al. (2006), Science 312, 727. [4] Floss C. et al. (2004) Science 303, 1355. [5] Nakamura-Messenger K. et al. (2006) Science, 314, 1439. [6] Claus G. and Nagy B., (1961) Nature 192, 594 [7] Aoki T., Akai J., Makino K. (2003) Int Symp.Evol. of Solar System Materials 5 [8] Garvie L

  14. Interactions between milk fat globules and green tea catechins.

    PubMed

    Rashidinejad, Ali; Birch, E John; Everett, David W

    2016-05-15

    The determination of putative chemical interactions between the milk fat globule membrane and green tea catechins provided useful information about the role of milk fat globules (MFGs) in high-fat dairy systems, such as cheese, and containing bioactive compounds, such as tea catechins. Catechins from green tea (125-1,000 ppm), including (+)-catechin, (-)-epigallocatechin gallate, and green tea extract were added to washed MFGs to examine possible interactions. The addition of catechins gave a significant change in the size and ζ-potential of MFGs. The recovery of different catechins from the milk fat globule suspensions was found to vary, suggesting selective association with the milk fat globule membranes. The interactions were further investigated using transmission electron microscopy and Fourier transform infra-red spectroscopy. It is suggested that catechins are localised in association with milk fat globule membrane domains as they contain both hydrophobic and hydrophilic moieties with potential points of molecular interaction. PMID:26775981

  15. Interactions between milk fat globules and green tea catechins.

    PubMed

    Rashidinejad, Ali; Birch, E John; Everett, David W

    2016-05-15

    The determination of putative chemical interactions between the milk fat globule membrane and green tea catechins provided useful information about the role of milk fat globules (MFGs) in high-fat dairy systems, such as cheese, and containing bioactive compounds, such as tea catechins. Catechins from green tea (125-1,000 ppm), including (+)-catechin, (-)-epigallocatechin gallate, and green tea extract were added to washed MFGs to examine possible interactions. The addition of catechins gave a significant change in the size and ζ-potential of MFGs. The recovery of different catechins from the milk fat globule suspensions was found to vary, suggesting selective association with the milk fat globule membranes. The interactions were further investigated using transmission electron microscopy and Fourier transform infra-red spectroscopy. It is suggested that catechins are localised in association with milk fat globule membrane domains as they contain both hydrophobic and hydrophilic moieties with potential points of molecular interaction.

  16. Milk Fat Globule structure & function; nanosciece comes to milk production

    PubMed Central

    Argov, Nurit; Lemay, Danielle G; German, J Bruce

    2009-01-01

    The biological process of fat globule assembly and secretion produces highly complex globule compositions and structures with many properties now recognized to be the direct result of these structures. During homogenization, fat globules are broken down and subsequently structures and surfaces different than the native state are formed. This process alters the milk fat globule unique macrostructure and the effects associated to their structure would be expected to be lost. In the present overview, the need for continued research of the fundamental aspects of the mechanism involved in milk fat globules synthesis secretion and size distribution, as well as establishing ways to regulate those processes are highlighted. Ultimately these insights will guide food technology to developing a new generation of structure based functional foods and as highlighted in this overview, dairy functional products should be the pioneering commodity. PMID:24363495

  17. Fractal Globules: A New Approach to Artificial Molecular Machines

    PubMed Central

    Avetisov, Vladik A.; Ivanov, Viktor A.; Meshkov, Dmitry A.; Nechaev, Sergei K.

    2014-01-01

    The over-damped relaxation of elastic networks constructed by contact maps of hierarchically folded fractal (crumpled) polymer globules was investigated in detail. It was found that the relaxation dynamics of an anisotropic fractal globule is very similar to the behavior of biological molecular machines like motor proteins. When it is perturbed, the system quickly relaxes to a low-dimensional manifold, M, with a large basin of attraction and then slowly approaches equilibrium, not escaping M. Taking these properties into account, it is suggested that fractal globules, even those made by synthetic polymers, are artificial molecular machines that can transform perturbations into directed quasimechanical motion along a defined path. PMID:25418305

  18. Fractal globules: a new approach to artificial molecular machines.

    PubMed

    Avetisov, Vladik A; Ivanov, Viktor A; Meshkov, Dmitry A; Nechaev, Sergei K

    2014-11-18

    The over-damped relaxation of elastic networks constructed by contact maps of hierarchically folded fractal (crumpled) polymer globules was investigated in detail. It was found that the relaxation dynamics of an anisotropic fractal globule is very similar to the behavior of biological molecular machines like motor proteins. When it is perturbed, the system quickly relaxes to a low-dimensional manifold, M, with a large basin of attraction and then slowly approaches equilibrium, not escaping M. Taking these properties into account, it is suggested that fractal globules, even those made by synthetic polymers, are artificial molecular machines that can transform perturbations into directed quasimechanical motion along a defined path. PMID:25418305

  19. Fractal globules: a new approach to artificial molecular machines.

    PubMed

    Avetisov, Vladik A; Ivanov, Viktor A; Meshkov, Dmitry A; Nechaev, Sergei K

    2014-11-18

    The over-damped relaxation of elastic networks constructed by contact maps of hierarchically folded fractal (crumpled) polymer globules was investigated in detail. It was found that the relaxation dynamics of an anisotropic fractal globule is very similar to the behavior of biological molecular machines like motor proteins. When it is perturbed, the system quickly relaxes to a low-dimensional manifold, M, with a large basin of attraction and then slowly approaches equilibrium, not escaping M. Taking these properties into account, it is suggested that fractal globules, even those made by synthetic polymers, are artificial molecular machines that can transform perturbations into directed quasimechanical motion along a defined path.

  20. Lipid-protein globules of avian egg yolk. Isolation and properties of globules stable in concentrated sodium chloride solution.

    PubMed

    Vadehra, D V; Bain, J M; Burley, R W

    1977-09-15

    A new type of globular particle, the 'insoluble yolk globule', was isolated from the egg yolk of three avian species (hen, duck, and emu) by centrifugation or gel-filtration chromatography. These globules are stable in NaCl and urea solutions at concentrations that dissolve or disrupt other constituents of yolk, The isolated globules are about 1% of the dry yolk of hen's and duck's eggs but about 8% emu's-egg yolk. Most of these globules are less than 2 micrometer in diameter. Electron micrographs of sections show a preponderance of globules in the range 0.125-0.25 micrometer, each with a thick shell surrounding a feature-less anterior. Globules with the same appearance were seen in sections of unfractionated yolk. Two kinds of larger particles were also observed: (i) particles with a distinct outer membrane and a vesiculated interior; (ii) featureless spheres, possibly of lipid. The insoluble yolk globules comprise protein (8-11% by dry wt.), phospholipid (31-35% total lipid), triacylglycerols (49-53%), cholesterol (8%) and cholesteryl esters (2-3%); the variations being among species. The phospholipid is accessible to phospholipase C. The isolated protein is heterogeneous and resembles the apoprotein from the yolk low-density lipoprotein.

  1. Organic Globules in Carbonaceous Chondrites: An Experimental Approach

    NASA Astrophysics Data System (ADS)

    Giese, C.-C.; ten Kate, I. L.; Plümper, O.; King, H. E.; Geisler, T.; Lenting, C.; Tielens, X.

    2016-08-01

    PAHs have been considered as material composing organic globules in CCs. In order to test the PAH precursor hypothesis, we conducted hydrothermal as well as melting experiments with two different types of PAHs.

  2. Molten salt electrolyte separator

    DOEpatents

    Kaun, Thomas D.

    1996-01-01

    A molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication.

  3. Molten salt technology

    SciTech Connect

    Lovering, D.G.

    1982-01-01

    In this volume, the historical background, scope, problems, economics, and future applications of molten salt technologies are discussed. Topics presented include molten salts in primary production of aluminum, general principles and handling and safety of the alkali metals, first-row transition metals, group VIII metals and B-group elements, solution electrochemistry, transport phenomena, corrosion in different molten salts, cells with molten salt electrolytes and reactants, fuel cell design, hydrocracking and liquefaction, heat storage in phase change materials, and nuclear technologies.

  4. Characterisation of molten globule-like state of sheep serum albumin at physiological pH.

    PubMed

    Dar, Mohammad Aasif; Wahiduzzaman; Haque, Md Anzarul; Islam, Asimul; Hassan, Md Imtaiyaz; Ahmad, Faizan

    2016-08-01

    Sheep serum albumin (SSA) is a 583 amino acid residues long multidomain monomeric protein which is rich in cysteine and low in tryptophan content. The serum albumins (from human, bovine and sheep) play a vital role among all proteins investigated until now, as they are the most copious circulatory proteins. We have purified SSA from sheep kidneys by a simple and efficient two-step purification procedure. Further, we have studied urea-induced denaturation of SSA by monitoring changes in the difference absorption coefficient at 287nm (Δε287), intrinsic fluorescence emission intensity at 347nm (F347) and mean residue ellipticity at 222nm ([θ]222) at pH 7.4 and 25°C. The coincidence of denaturation curves of these optical properties suggests that urea-induced denaturation is a bi-phasic process (native (N) state↔intermediate (X) state↔denatured (D) state) with a stable intermediate populated around 4.2-4.7M urea. The intermediate (X) state was further characterized by the far-UV and near-UV CD, dynamic light scattering (DLS) and fluorescence using 1-anilinonaphthalene-8-sulfonic acid (ANS) binding method. All denaturation curves were analyzed for Gibbs free energy changes associated with the equilibria, N state↔X state and X state↔D state in the absence of urea. PMID:27180298

  5. On the origins of polarization holes in Bok globules

    NASA Astrophysics Data System (ADS)

    Brauer, R.; Wolf, S.; Reissl, S.

    2016-04-01

    Context. Polarimetric observations of Bok globules frequently show a decrease in the degree of polarization towards their central dense regions (polarization holes). This behaviour is usually explained with increased disalignment owing to high density and temperature, or insufficient angular resolution of a possibly complex magnetic field structure. Aims: We investigate whether a significant decrease in polarized emission of dense regions in Bok globules is possible under certain physical conditions. For instance, we evaluate the impact of optical depth effects and various properties of the dust phase. Methods: We use radiative transfer modelling to calculate the temperature structure of an analytical Bok globule model and simulate the polarized thermal emission of elongated dust grains. For the alignment of the dust grains, we consider a magnetic field and include radiative torque and internal alignment. Results: Besides the usual explanations, selected conditions of the temperature and density distribution, the dust phase and the magnetic field are also able to significantly decrease the polarized emission of dense regions in Bok globules. Taking submm/mm grains and typical column densities of existing Bok globules into consideration, the optical depth is high enough to decrease the degree of polarization by up to ΔP ~ 10%. If limited to the densest regions, dust grain growth to submm/mm size and accumulated graphite grains decrease the degree of polarization by up to ΔP ~ 10% and ΔP ~ 5%, respectively. However, the effect of the graphite grains occurs only if they do not align with the magnetic field.

  6. Star formation in the globules of the Trifid Nebula

    NASA Astrophysics Data System (ADS)

    Cernicharo, Jose; Lefloch, Bertrand; Garcia Lopez, Ramon; Esteban, Cesar

    We present optical and millimeter (continuum and molecular) observations of a cometary globule in the Trifid nebula showing clear signs of star formation activity. The globule is associated with a long jet finishing in a large bow shock. The HH jet can be seen in all the popular pictures of the Trifid. It has remained unrevealed although it has been in front of our eyes since the first high sensitivity photographic pictures of the Trifid. The jet emanates from the head of a cometary globule submitted to the strong UV field of the ionizing star of the Trifid. The continuum emission at 230 GHz follows the globule's head contour and consists of extended and weak emission plus a strong point source from where the jet seems to arise. High resolution spectroscopy in the SII line at 6730 A indicates that the jet is practically in the plane of the sky. The dust emission arises from a clump of ~= 5 M_\\odot. The molecular observations cover a larger surface and indicate a total mass for the globule of 30-50 M_\\odot.

  7. Brief heat treatment causes a structural change and enhances cytotoxicity of the Escherichia coli α-hemolysin.

    PubMed

    Aulik, Nicole A; Atapattu, Dhammika N; Czuprynski, Charles J; McCaslin, Darrel R

    2013-02-01

    α-Hemolysin (HLY) is an important virulence factor for uropathogenic Escherichia coli. HLY is a member of the RTX family of exotoxins secreted by a number of Gram-negative bacteria. Recently, it was reported that a related RTX toxin, the Mannheimia haemolytica leukotoxin, exhibits increased cytotoxicity following brief heat treatment. In this article, we show that brief heat treatment (1 min at 100°C) increases cytotoxicity of HLY for human bladder cells, kidney epithelial cells (A498) and neutrophils. Heat treatment also increased hemolysis of human red blood cells (RBCs). Furthermore, heat treatment of previously inactived HLY restored its cytotoxicity. Heat-activated and native HLY both required glycophorin A to lyse RBCs. Native and heat-activated HLY appeared to bind equally well to the surface of A498 cells; although, Western blot analyses demonstrated binding to different proteins on the surface. Confocal microscopy revealed that heat-activated HLY bound more extensively to internal structures of permeabilized A498 cells than did native HLY. Several lines of spectroscopic evidence demonstrate irreversible changes in the structure of heat activated compared to native HLY. We show changes in secondary structure, increased exposure of tryptophan residues to the aqueous environment, an increase in molecular dimension and an increase in hydrophobic surface area. These properties are among the most common characteristics described for the molten globule state, first identified as an intermediate in protein folding. We hypothesize that brief heat treatment of HLY causes a conformational change leading to significant differences in protein-protein interactions that result in increased cytotoxicity for target cells. PMID:22994841

  8. Electrodeposition of molten silicon

    DOEpatents

    De Mattei, Robert C.; Elwell, Dennis; Feigelson, Robert S.

    1981-01-01

    Silicon dioxide is dissolved in a molten electrolytic bath, preferably comprising barium oxide and barium fluoride. A direct current is passed between an anode and a cathode in the bath to reduce the dissolved silicon dioxide to non-alloyed silicon in molten form, which is removed from the bath.

  9. Electrodeposition of molten silicon

    SciTech Connect

    De Mattei, R.C.; Elwell, D.; Feigelson, R.S.

    1981-09-29

    Silicon dioxide is dissolved in a molten electrolytic bath, preferably comprising barium oxide and barium fluoride. A direct current is passed between an anode and a cathode in the bath to reduce the dissolved silicon dioxide to non-alloyed silicon in molten form, which is then removed from the bath.

  10. Molten salt electrolyte separator

    DOEpatents

    Kaun, T.D.

    1996-07-09

    The patent describes a molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication. 5 figs.

  11. ISO Observations of Starless Bok Globules: Usually No Embedded Stars

    NASA Technical Reports Server (NTRS)

    Clemens, D.; Byrne, A.; Yun, J.; Kane, B.

    1996-01-01

    We have used ISOCAM to search the cores of a sample of small Bok globules previously classified to be mostly starless based on analysis of IRAS data. The ISO observations at 6.75microns (LW2 filter) and 14.5microns (LW3 filter) were sufficiently deep to enable detection of any low-mass hydrogen burning star or young stellar object (YSO) embedded in these globules. Of the 20 Bok globules observed by ISOCAM to date, we have reduced the data for 14. Of these, 13 show no evidence for faint red (S(sub v)(LW3) greater than S(sub v)(LW2)) stars missed by IRAS. One (CB68) does show the first mid-infrared detection of the very cool IRAS source toward this cloud, and may be a Class I or 0 YSO. We conclude, based on these new ISO observations, that Bok globules which have no IRAS sources are in general bona fide starless molecular clouds.

  12. Microsecond Rearrangements of Hydrophobic Clusters in an Initially Collapsed Globule Prime Structure Formation during the Folding of a Small Protein.

    PubMed

    Goluguri, Rama Reddy; Udgaonkar, Jayant B

    2016-07-31

    Determining how polypeptide chain collapse initiates structure formation during protein folding is a long standing goal. It has been challenging to characterize experimentally the dynamics of the polypeptide chain, which lead to the formation of a compact kinetic molten globule (MG) in about a millisecond. In this study, the sub-millisecond events that occur early during the folding of monellin from the guanidine hydrochloride-unfolded state have been characterized using multiple fluorescence and fluorescence resonance energy transfer probes. The kinetic MG is shown to form in a noncooperative manner from the unfolded (U) state as a result of at least three different processes happening during the first millisecond of folding. Initial chain compaction completes within the first 37μs, and further compaction occurs only after structure formation commences at a few milliseconds of folding. The transient nonnative and native-like hydrophobic clusters with side chains of certain residues buried form during the initial chain collapse and the nonnative clusters quickly disassemble. Subsequently, partial chain desolvation occurs, leading to the formation of a kinetic MG. The initial chain compaction and subsequent chain rearrangement appear to be barrierless processes. The two structural rearrangements within the collapsed globule appear to prime the protein for the actual folding transition. PMID:27370109

  13. Proteome profile and biological activity of caprine, bovine and human milk fat globules.

    PubMed

    Spertino, Stefano; Cipriani, Valentina; De Angelis, Chiara; Giuffrida, Maria Gabriella; Marsano, Francesco; Cavaletto, Maria

    2012-04-01

    Upon combining bidimensional electrophoresis with monodimensional separation, a more comprehensive analysis of the milk fat globule membrane has been obtained. The proteomic profile of caprine milk fat globules revealed the presence of butyrophilin, lactadherin and perilipin as the major proteins, they were also associated to bovine and human milk fat globule membranes. Xanthine dehydrogenase/oxidase has been detected only in monodimensional gels. Biological activity of milk fat globules has been evaluated in Caco2-cells, as a representative model of the intestinal barrier. The increase of cell viability was indicative of a potential nutraceutical role for the whole milk fat globule, suggesting a possible employment in milk formula preparation.

  14. Rise of the Helix from a Collapsed Globule during the Folding of Monellin.

    PubMed

    Goluguri, Rama Reddy; Udgaonkar, Jayant B

    2015-09-01

    Early kinetic intermediates observed during the folding of many proteins are invariably compact and appear to possess some secondary structure. Consequently, it has been difficult to understand whether compaction drives secondary structure formation or secondary structure formation facilitates compaction during folding. In this study of the folding of single-chain monellin, it is shown that a kinetic molten globule (MG) is populated at 2 ms of folding. Far-UV circular dichroism (CD) measurements show that the kinetic MG is devoid of any helical structure even under the most stabilizing folding conditions. Multisite fluorescence resonance energy transfer (FRET) measurements show that the kinetic MG is compact with different segments having contracted to different extents. It is shown that the sequence segment that goes on to form the sole helix in the native protein is fully collapsed in the kinetic MG. This segment expands to accommodate the helix as the kinetic MG folds further to the native state, while other segments of the protein contract. Helix formation starting from the kinetic MG is shown to occur in multiple kinetic steps, whether measured by far-UV CD or by FRET. PMID:26258844

  15. Molten metal reactors

    DOEpatents

    Bingham, Dennis N; Klingler, Kerry M; Turner, Terry D; Wilding, Bruce M

    2013-11-05

    A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

  16. Facilitated diffusion of proteins through crumpled fractal DNA globules

    NASA Astrophysics Data System (ADS)

    Smrek, Jan; Grosberg, Alexander Y.

    2015-07-01

    We explore how the specific fractal globule conformation, found for the chromatin fiber of higher eukaryotes and topologically constrained dense polymers, affects the facilitated diffusion of proteins in this environment. Using scaling arguments and supporting Monte Carlo simulations, we relate DNA looping probability distribution, fractal dimension, and protein nonspecific affinity for the DNA to the effective diffusion parameters of the proteins. We explicitly consider correlations between subsequent readsorption events of the proteins, and we find that facilitated diffusion is faster for the crumpled globule conformation with high intersegmental surface dimension than in the case of dense fractal conformations with smooth surfaces. As a byproduct, we obtain an expression for the macroscopic conductivity of a hypothetic material consisting of conducting fractal nanowires immersed in a weakly conducting medium.

  17. Facilitated diffusion of proteins through crumpled fractal DNA globules.

    PubMed

    Smrek, Jan; Grosberg, Alexander Y

    2015-07-01

    We explore how the specific fractal globule conformation, found for the chromatin fiber of higher eukaryotes and topologically constrained dense polymers, affects the facilitated diffusion of proteins in this environment. Using scaling arguments and supporting Monte Carlo simulations, we relate DNA looping probability distribution, fractal dimension, and protein nonspecific affinity for the DNA to the effective diffusion parameters of the proteins. We explicitly consider correlations between subsequent readsorption events of the proteins, and we find that facilitated diffusion is faster for the crumpled globule conformation with high intersegmental surface dimension than in the case of dense fractal conformations with smooth surfaces. As a byproduct, we obtain an expression for the macroscopic conductivity of a hypothetic material consisting of conducting fractal nanowires immersed in a weakly conducting medium.

  18. Ionization front interactions and the formation of globules

    NASA Astrophysics Data System (ADS)

    Brand, P. W. J. L.

    1981-10-01

    It is assumed that an H II region has evolved inside a molecular cloud. The interactions that result from the expanding shell of compressed molecular gas reaching the edge of the cloud are calculated, and the instability of the ionization front to the formation of globules is investigated. The rarefaction wave which is reflected from the contact discontinuity as the leading shock passes through the edge of the cloud accelerates the ionization front, and since conditions at the front satisfy Capriotti's criterion for instability, the shell breaks up. The size of the fragment so created is determined by the thickness of the compressed shell. If the shell phase of H II region evolution has proceeded significantly, then globules of up to a fraction of a solar mass may be formed in an H II region caused by a star with an ionizing luminosity of 10 to the 49th photons/sec in a molecular cloud of density 1000/cu cm. These globules may survive the ionizing flux from the star, and will be driven from the cloud by the rocket effect.

  19. PIG (partially ionized globule) anatomy - Density and temperature structure of the bright-rimmed globule IC 1396E

    NASA Technical Reports Server (NTRS)

    Serabyn, E.; Guesten, R.; Mundy, L.

    1993-01-01

    The density and temperature structure of the bright-rimmed cometary globule IC 1396E is estimated, and the possibility that recent internal star formation was triggered by the ionization front in its southern surface is assessed. On the basis of NH3 data, gas temperatures in the globule are found to increase outward from the center, from a minimum of 17 K in its tail to a maximum of 26 K on the surface most directly facing the stars ionizing IC 1396. On the basis of a microturbulent radiative transfer code to model the radial dependence of the CS line intensities, and also the intensities of the optically thin 2-1 and 5-4 lines toward the cloud center, a radial density dependence of r exp -1.55 to r exp -1.75 is found.

  20. Air stable iron/iron carbide magnetic nanoparticles embedded in amorphous carbon globules

    NASA Astrophysics Data System (ADS)

    Sadhanala, Hari Krishna; Nanda, Karuna Kar

    2015-06-01

    We have synthesized Fe/Fe3C magnetic nanoparticles embedded in an amorphous carbon globule by pyrolysing of benzene, ferrocene and hydroboric acid. The diameter of the globules is ˜ 1 µm and that of Fe/Fe3C magnetic nanoparticles is ˜ 40 nm. The globules exhibit ferromagnetic like behavior and the magnetization as well as the coercivity is found to increases with decreasing temperature.

  1. The formation of elephant-trunk globules in the Rosette nebula: CO observations

    SciTech Connect

    Schneps, M.H.; Ho, P.T.P.; Barrett, A.H.

    1980-08-15

    The prominent elephant-trunk globules in the northwest quadrant of the Rosette nebula have been observed in the microwave lines of CO and /sup 13/CO (J=1..-->..0). The CO emission closely follows the optical outline of the obscuring material and leaves little doubt that the emission is associated with the globules. The physical characteristics derived are typical of those observed in other dust globules which are not necessarily associated with H II regions.

  2. Mars Life? - Orange-colored Carbonate Mineral Globules

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This photograph shows orange-colored carbonate mineral globules found in a meteorite, called ALH84001, believed to have once been a part of Mars. These carbonate minerals in the meteorite are believed to have been formed on Mars more than 3.6 billion years ago. Their structure and chemistry suggest that they may have been formed with the assistance of primitive, bacteria-like living organisms. A two-year investigation by a NASA research team found organic molecules, mineral features characteristic of biological activity and possible microscopic fossils inside of carbonate minerals such as these in the meteorite.

  3. In situ observation of D-rich carbonaceous globules embedded in NWA 801 CR2 chondrite

    NASA Astrophysics Data System (ADS)

    Hashiguchi, Minako; Kobayashi, Sachio; Yurimoto, Hisayoshi

    2013-12-01

    Eighty-five D-rich carbonaceous particles were identified in the matrix of the NWA 801 CR2 chondrite using isotope microscopy. The occurrence of 67 D-rich carbonaceous particles was characterized using secondary electron microscopy combined with X-ray elemental mapping. The close association of H and C, and D-enrichment suggests that the D-rich carbonaceous particles correspond to organic matter. The D-rich organic particles were scattered ubiquitously throughout the matrix at a concentration of approximately 660 ppm. The morphology of the D-rich carbonaceous particles is globular up to about 1 μm in diameter and is classified into four types: ring globules, round globules, irregular-shaped globules, and globule aggregates. The ring globules are ring-shaped organic matter containing silicate and/or oxide, with or without a void in the center. This is the first report of silicate and oxide grains surrounded by D-rich organic matter. The globule aggregates are composed of several D-rich organic globules mixed with silicates. Morphology of ring globules is very similar to core-mantle grain produced in the molecular cloud or in the outer solar nebula inferring by astronomy, suggesting that the organic globules have formed by UV photolysis in the ice mantle. Silicates or oxides attached to D-rich organic globules are the first observation among chondrites so far and may be unique nature of CR2 chondrites. The hydrogen isotopic compositions of the ring globules, round globules, irregular-shaped globules, and globule aggregates are δD = 3000-4800, 2900-8100, 2700-11,000, and 2500-11,000‰, respectively. Variations of D/H ratio of these organic globules seemed to be attributed to variations of D/H ratio of the organic radicals or differences of content of the D-rich organic radicals. There are no significant differences in the hydrogen isotopic compositions among the four types of D-rich carbonaceous matter. The D-enrichments suggest that these organic globules have

  4. Isolation of a novel oil globule protein from the green alga Haematococcus pluvialis (Chlorophyceae).

    PubMed

    Peled, Ehud; Leu, Stefan; Zarka, Aliza; Weiss, Meira; Pick, Uri; Khozin-Goldberg, Inna; Boussiba, Sammy

    2011-09-01

    Cytoplasmic oil globules of Haematococcus pluvialis (Chlorophyceae) were isolated and analyzed for pigments, lipids and proteins. Astaxanthin appeared to be the only pigment deposited in the globules. Triacyglycerols were the main lipids (more than 90% of total fatty acids) in both the cell-free extract and in the oil globules. Lipid profile analysis of the oil globules showed that relative to the cell-free extract, they were enriched with extraplastidial lipids. A fatty acids profile revealed that the major fatty acids in the isolated globules were oleic acid (18:1) and linoleic acid (18:2). Protein extracts from the globules revealed seven enriched protein bands, all of which were possible globule-associated proteins. A major 33-kDa globule protein was partially sequenced by MS/MS analysis, and degenerate DNA primers were prepared and utilized to clone its encoding gene from cDNA extracted from cells grown in a nitrogen depleted medium under high light. The sequence of this 275-amino acid protein, termed the Haematococcus Oil Globule Protein (HOGP), revealed partial homology with a Chlamydomonas reinhardtii oil globule protein and with undefined proteins from other green algae. The HOGP transcript was barely detectable in vegetative cells, but its level increased by more than 100 fold within 12 h of exposure to nitrogen depletion/high light conditions, which induced oil accumulation. HOGP is the first oil-globule-associated protein to be identified in H. pluvialis, and it is a member of a novel gene family that may be unique to green microalgae. PMID:21732215

  5. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-01-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  6. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Delcul, G. D.; Dai, S.; Metcalf, D. H.

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior which can be used effectively to reduce the amount of development required for future systems, some significant molten salt chemical questions must still be addressed.

  7. Molten salt techniques. Volume 3

    SciTech Connect

    Lovering, D.G.; Gale, R.J.

    1987-01-01

    This collection of five papers on molten salts deals with the following specific topics: the actinides and their salts, including their availability along with techniques and equipment for their handling, preparation, purification, and physical property measurement; cryolite systems and methods for their handling, preparation, and thermodynamic and physicochemical property assessment, as well as the use of electrodes in molten cryolite; the theory, construction, and application of reference electrodes for molten salt electrolytes; neutron diffraction in molten salt systems including isotope exchange methods for sample preparation; and dry boxes and inert atmosphere techniques for molten salt handling and analysis.

  8. Fluid dynamics and kinematics of molten metals in the low-gravity environment of Skylab

    NASA Technical Reports Server (NTRS)

    Bourgeois, S. V.; Brashears, M. R.

    1974-01-01

    The response of molten metals to mechanical and thermal driving forces in nominal and microgravity is analyzed both theoretically and experimentally. The magnitude and transient behavior of internal fluid circulations, surface deformations, and globule trajectories and their effects on solidification in the Skylab electron beam sphere forming and metals melting experiments are determined. The theoretical approach consists of dimensional analysis of the governing differential equations. Experimental aspects include evaluation of specimens from terrestrial, KC-135 research aircraft, and actual Skylab tests and analysis of high speed movies taken during the melting processes. Several gravity variations and gravity independent results were successfully predicted based on expected differences and similarities in fluid dynamics.

  9. Proteomics of the milk fat globule membrane from Camelus dromedarius.

    PubMed

    Saadaoui, Besma; Henry, Céline; Khorchani, Touhami; Mars, Mohamed; Martin, Patrice; Cebo, Christelle

    2013-04-01

    Camel milk has been widely characterized with regards to casein and whey proteins. However, in camelids, almost nothing is known about the milk fat globule membrane (MFGM), the membrane surrounding fat globules in milk. The purpose of this study was thus to identify MFGM proteins from Camelus dromedarius milk. Major MFGM proteins (namely, fatty acid synthase, xanthine oxidase, butyrophilin, lactadherin, and adipophilin) already evidenced in cow milk were identified in camel milk using MS. In addition, a 1D-LC-MS/MS approach led us to identify 322 functional groups of proteins associated with the camel MFGM. Dromedary MFGM proteins were then classified into functional categories using DAVID (the Database for Annotation, Visualization, and Integrated Discovery) bioinformatics resources. More than 50% of MFGM proteins from camel milk were found to be integral membrane proteins (mostly belonging to the plasma membrane), or proteins associated to the membrane. Enriched GO terms associated with MFGM proteins from camel milk were protein transport (p-value = 1.73 × 10(-14)), translation (p-value = 1.08 × 10(-11)), lipid biosynthetic process (p-value = 6.72 × 10(-10)), hexose metabolic process (p-value = 1.89 × 10(-04)), and actin cytoskeleton organization (p-value = 2.72 × 10(-04)). These findings will help to contribute to a better characterization of camel milk. Identified MFGM proteins from camel milk may also provide new insight into lipid droplet formation in the mammary epithelial cell.

  10. Catalytically active alkaline molten globular enzyme: Effect of pH and temperature on the structural integrity of 5-aminolevulinate synthase.

    PubMed

    Stojanovski, Bosko M; Breydo, Leonid; Hunter, Gregory A; Uversky, Vladimir N; Ferreira, Gloria C

    2014-12-01

    5-Aminolevulinate synthase (ALAS), a pyridoxal-5'phosphate (PLP)-dependent enzyme, catalyzes the first step of heme biosynthesis in mammals. Circular dichroism (CD) and fluorescence spectroscopies were used to examine the effects of pH (1.0-3.0 and 7.5-10.5) and temperature (20 and 37°C) on the structural integrity of ALAS. The secondary structure, as deduced from far-UV CD, is mostly resilient to pH and temperature changes. Partial unfolding was observed at pH2.0, but further decreasing pH resulted in acid-induced refolding of the secondary structure to nearly native levels. The tertiary structure rigidity, monitored by near-UV CD, is lost under acidic and specific alkaline conditions (pH10.5 and pH9.5/37°C), where ALAS populates a molten globule state. As the enzyme becomes less structured with increased alkalinity, the chiral environment of the internal aldimine is also modified, with a shift from a 420nm to 330nm dichroic band. Under acidic conditions, the PLP cofactor dissociates from ALAS. Reaction with 8-anilino-1-naphthalenesulfonic acid corroborates increased exposure of hydrophobic clusters in the alkaline and acidic molten globules, although the reaction is more pronounced with the latter. Furthermore, quenching the intrinsic fluorescence of ALAS with acrylamide at pH1.0 and 9.5 yielded subtly different dynamic quenching constants. The alkaline molten globule state of ALAS is catalytically active (pH9.5/37°C), although the kcat value is significantly decreased. Finally, the binding of 5-aminolevulinate restricts conformational fluctuations in the alkaline molten globule. Overall, our findings prove how the structural plasticity of ALAS contributes to reaching a functional enzyme.

  11. Catalytically active alkaline molten globular enzyme: Effect of pH and temperature on the structural integrity of 5-aminolevulinate synthase.

    PubMed

    Stojanovski, Bosko M; Breydo, Leonid; Hunter, Gregory A; Uversky, Vladimir N; Ferreira, Gloria C

    2014-12-01

    5-Aminolevulinate synthase (ALAS), a pyridoxal-5'phosphate (PLP)-dependent enzyme, catalyzes the first step of heme biosynthesis in mammals. Circular dichroism (CD) and fluorescence spectroscopies were used to examine the effects of pH (1.0-3.0 and 7.5-10.5) and temperature (20 and 37°C) on the structural integrity of ALAS. The secondary structure, as deduced from far-UV CD, is mostly resilient to pH and temperature changes. Partial unfolding was observed at pH2.0, but further decreasing pH resulted in acid-induced refolding of the secondary structure to nearly native levels. The tertiary structure rigidity, monitored by near-UV CD, is lost under acidic and specific alkaline conditions (pH10.5 and pH9.5/37°C), where ALAS populates a molten globule state. As the enzyme becomes less structured with increased alkalinity, the chiral environment of the internal aldimine is also modified, with a shift from a 420nm to 330nm dichroic band. Under acidic conditions, the PLP cofactor dissociates from ALAS. Reaction with 8-anilino-1-naphthalenesulfonic acid corroborates increased exposure of hydrophobic clusters in the alkaline and acidic molten globules, although the reaction is more pronounced with the latter. Furthermore, quenching the intrinsic fluorescence of ALAS with acrylamide at pH1.0 and 9.5 yielded subtly different dynamic quenching constants. The alkaline molten globule state of ALAS is catalytically active (pH9.5/37°C), although the kcat value is significantly decreased. Finally, the binding of 5-aminolevulinate restricts conformational fluctuations in the alkaline molten globule. Overall, our findings prove how the structural plasticity of ALAS contributes to reaching a functional enzyme. PMID:25240868

  12. Molten salt electrochemistry

    SciTech Connect

    Gallegos, U.F.; Williamson, M.A.

    1997-12-31

    The objective of this work is to develop preparation and clean-up processes for the fuel and carrier salt used in the Los Alamos Accelerator-Driven Transmutation Technology molten salt nuclear system. The front-end or fuel preparation process focuses on the removal of fission products, uranium, and zirconium from spent nuclear fuel by utilizing electrochemical methods. The same method provide the separation of the transition metal fission products at the back end of the fuel cycle. Molten salts provide a natural medium for the separation of actinides and fission products from one another because they are robust, radiation resistant solvents that can be recycled. The presentation will describe the design of the electrochemistry system, the method used for salt purification, and results of preliminary experiments.

  13. Molten core retention assembly

    DOEpatents

    Lampe, Robert F.

    1976-06-22

    Molten fuel produced in a core overheating accident is caught by a molten core retention assembly consisting of a horizontal baffle plate having a plurality of openings therein, heat exchange tubes having flow holes near the top thereof mounted in the openings, and a cylindrical, imperforate baffle attached to the plate and surrounding the tubes. The baffle assembly is supported from the core support plate of the reactor by a plurality of hanger rods which are welded to radial beams passing under the baffle plate and intermittently welded thereto. Preferably the upper end of the cylindrical baffle terminates in an outwardly facing lip to which are welded a plurality of bearings having slots therein adapted to accept the hanger rods.

  14. Electrophoresis of small particles and fluid globules in weak electrolytes

    NASA Technical Reports Server (NTRS)

    Baygents, J. C.; Saville, D. A.

    1991-01-01

    An examination is conducted of the influence of partial ionization on the electrophoresis of small particles and fluid globules, with a view to the nature of conditions under which dissociation-association (D-A) alters electrokinetics. It is found that, since D-A processes are important in cases where double-layer polarization and relaxation would otherwise prevail, the predicted effect on electrophoretic mobility is greatest for the drops and bubbles whose surfaces are fluid and convection within the interface is significant. While the computation scheme used applies only to situations where forcing-field magnitude is small, the results obtained indicate that D-A processes involving ionogenic solutes may be significant in apolar liquids where electrokinetic phenomena are driven by strong forcing fields.

  15. Major proteins of the goat milk fat globule membrane.

    PubMed

    Cebo, C; Caillat, H; Bouvier, F; Martin, P

    2010-03-01

    Fat is present in milk as droplets of triglycerides surrounded by a complex membrane derived from the mammary epithelial cell called milk fat globule membrane (MFGM). Although numerous studies have been published on human or bovine MFGM proteins, to date few studies exist on MFGM proteins from goat milk. The objective of this study was thus to investigate the protein composition of the goat MFGM. Milk fat globule membrane proteins from goat milk were separated by 6% and 10% sodium dodecyl sulfate-PAGE and were Coomassie or periodic acid-Schiff stained. Most of MFGM proteins [mucin-1, fatty acid synthase, xanthine oxidase, butyrophilin, lactadherin (MFG EGF-8, MFG-E8), and adipophilin] already described in cow milk were identified in goat milk using peptide mass fingerprinting. In addition, lectin staining provided a preliminary characterization of carbohydrate structures occurring on MFGM proteins from goat milk depending on alpha(S1)-casein genotype and lactation stage. We provide here first evidence of the presence of O-glycans on fatty acid synthase and xanthine oxidase from goat milk. A prominent difference between the cow and the goat species was demonstrated for lactadherin. Indeed, whereas 2 polypeptide chains were easily identified by peptide mass fingerprinting matrix-assisted laser desorption/ionization-time of flight analysis within bovine MFGM proteins, lactadherin from goat milk consisted of a single polypeptide chain. Another striking observation was the presence of caseins associated with MFGM preparations from goat milk, whereas virtually no caseins were found in MFGM extracts from bovine milk. Taken together, these observations strongly support the existence of a singular secretion mode previously hypothesized in the goat.

  16. Hyperinsulinemic clamp modulates milk fat globule lipid composition in goats.

    PubMed

    Argov-Argaman, N; Mbogori, T; Sabastian, C; Shamay, A; Mabjeesh, S J

    2012-10-01

    We determined the effect of insulin on milk fatty acid (FA) and lipid composition in goats. Four dairy goats, 150 d in milk, were subjected to hyperinsulinemic clamp (treatment) or saline (control) infusion for 4d in a crossover design study. Composition and concentration of plasma and milk FA, triglycerides, phospholipids, sphingolipids, and cholesterol were determined. Mammary gland biopsies were taken at the end of each experimental period and lipogenic gene expression was determined. Plasma insulin was elevated 3.5-fold, whereas plasma glucose remained constant during the treatment period. Feed intake decreased by 26% and fat yield decreased by 17% relative to controls. No change in nonesterified FA concentration was found between controls and treatment. Compared with controls, insulin decreased yield of long-chain saturated FA by 14%. Milk concentration of long-chain FA was reduced by 3%, whereas that of medium-chain FA increased by 5% during the treatment compared with controls. Hyperinsulinemic clamps increased the yields of milk phospholipids by 9% and cholesterol by 16%, whereas it only tended to decrease triglyceride yields (by 11%). Hyperinsulinemic treatment resulted in compositional changes in the milk fat globule membrane, as reflected by 15 and 9% decreases in phosphatidylethanolamine and phosphatidylcholine concentrations, respectively. Lipogenic gene expression of acyl coenzyme A carboxylase, stearoyl coenzyme A desaturase, and FA synthase did not change, whereas lipoprotein lipase gene expression tended toward an increase in the treatment period compared with controls. Hyperinsulinemic clamps reduce the availability of long-chain FA, which are considered to originate from the diet and adipose lipolysis for milk lipid synthesis by the mammary gland of goats. Under these conditions, long-chain FA might be preferentially channeled to phospholipid rather than triglyceride synthesis, hence increasing phospholipid yields. Mechanisms determining FA

  17. Molten salt spectroelectrochemistry: recent developments

    SciTech Connect

    Mamantov, G.; Chapman, D.M.; Harward, B.L.; Klatt, L.N.; Smith, G.P.

    1985-01-01

    Molten salt spectroelectrochemistry will be reviewed in this paper. UV-visible transmission, infrared reflectance, resonance and normal Raman, and electron spin resonance spectroelectrochemistry have been used for molten salt studies. Two recent applications of uv-visible transmission spectroelectrochemistry to studies of organic and inorganic solutes in molten SbCl/sub 3/-AlCl/sub 3/-N-(1-butyl)pyridinium chloride and AlCl/sub 3/-NaCl will be described.

  18. Molten fluoride fuel salt chemistry

    NASA Astrophysics Data System (ADS)

    Toth, L. M.; Del Cul, G. D.; Dai, S.; Metcalf, D. H.

    1995-09-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior, processing and recycle of the fuel components is a necessary factor if future systems are to be established.

  19. Molten fluoride fuel salt chemistry

    SciTech Connect

    Toth, L.M.; Del Cul, G.D.; Dai, S.; Metcalf, D.H.

    1994-09-01

    The chemistry of molten fluorides is traced from their development as fuels in the Molten Salt Reactor Experiment with important factors in their selection being discussed. Key chemical characteristics such as solubility, redox behavior, and chemical activity are explained as they relate to the behavior of molten fluoride fuel systems. Fission product behavior is described along with processing experience. Development requirements for fitting the current state of the chemistry to modern nuclear fuel system are described. It is concluded that while much is known about molten fluoride behavior, processing and recycle of the fuel components is a necessary factor if future systems are to be established.

  20. Detection and removal of molten salts from molten aluminum alloys

    SciTech Connect

    K. Butcher; D. Smith; C. L. Lin; L. Aubrey

    1999-08-02

    Molten salts are one source of inclusions and defects in aluminum ingots and cast shapes. A selective adsorption media was used to remove these inclusions and a device for detection of molten salts was tested. This set of experiments is described and the results are presented and analyzed.

  1. 13. VIEW OF THE MOLTEN SALT EXTRACTION LINE. THE MOLTEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW OF THE MOLTEN SALT EXTRACTION LINE. THE MOLTEN SALT EXTRACTION PROCESS WAS USED TO PURIFY PLUTONIUM BY REMOVING AMERICIUM, A DECAY BY-PRODUCT OF PLUTONIUM. (1/98) - Rocky Flats Plant, Plutonium Fabrication, Central section of Plant, Golden, Jefferson County, CO

  2. Molten carbonate fuel cell

    DOEpatents

    Kaun, T.D.; Smith, J.L.

    1986-07-08

    A molten electrolyte fuel cell is disclosed with an array of stacked cells and cell enclosures isolating each cell except for access to gas manifolds for the supply of fuel or oxidant gas or the removal of waste gas. The cell enclosures collectively provide an enclosure for the array and effectively avoid the problems of electrolyte migration and the previous need for compression of stack components. The fuel cell further includes an inner housing about and in cooperation with the array enclosure to provide a manifold system with isolated chambers for the supply and removal of gases. An external insulated housing about the inner housing provides thermal isolation to the cell components.

  3. Molten carbonate fuel cell

    DOEpatents

    Kaun, Thomas D.; Smith, James L.

    1987-01-01

    A molten electrolyte fuel cell with an array of stacked cells and cell enclosures isolating each cell except for access to gas manifolds for the supply of fuel or oxidant gas or the removal of waste gas, the cell enclosures collectively providing an enclosure for the array and effectively avoiding the problems of electrolyte migration and the previous need for compression of stack components, the fuel cell further including an inner housing about and in cooperation with the array enclosure to provide a manifold system with isolated chambers for the supply and removal of gases. An external insulated housing about the inner housing provides thermal isolation to the cell components.

  4. Molten salt lithium cells

    DOEpatents

    Raistrick, I.D.; Poris, J.; Huggins, R.A.

    1980-07-18

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400 to 500/sup 0/C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell which may be operated at temperatures between about 100 to 170/sup 0/C. The cell is comprised of an electrolyte, which preferably includes lithium nitrate, and a lithium or lithium alloy electrode.

  5. Molten salt lithium cells

    DOEpatents

    Raistrick, Ian D.; Poris, Jaime; Huggins, Robert A.

    1983-01-01

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

  6. Molten salt lithium cells

    DOEpatents

    Raistrick, Ian D.; Poris, Jaime; Huggins, Robert A.

    1982-02-09

    Lithium-based cells are promising for applications such as electric vehicles and load-leveling for power plants since lithium is very electropositive and light weight. One type of lithium-based cell utilizes a molten salt electrolyte and is operated in the temperature range of about 400.degree.-500.degree. C. Such high temperature operation accelerates corrosion problems and a substantial amount of energy is lost through heat transfer. The present invention provides an electrochemical cell (10) which may be operated at temperatures between about 100.degree.-170.degree. C. Cell (10) comprises an electrolyte (16), which preferably includes lithium nitrate, and a lithium or lithium alloy electrode (12).

  7. Dual intercalating molten electrolyte batteries

    SciTech Connect

    Carlin, R.T.; De Long, H.C.; Fuller, J.; Trulove, P.C. . Frank J. Seiler Research Lab.)

    1994-07-01

    The reductive and oxidative intercalation of ions into graphite from room-temperature and low temperature molten salts is demonstrated. For this investigation, the molten salts use 1-ethyl-3-methylimidazolium (EMI[sup +]) or 1,2-dimethyl-3-propylimidazolium (DMPI[sup +]) as the cation and AlCl[sup [minus

  8. Removing Dross From Molten Solder

    NASA Technical Reports Server (NTRS)

    Webb, Winston S.

    1990-01-01

    Automatic device helps to assure good solder connections. Machine wipes dross away from area on surface of molten solder in pot. Sweeps across surface of molten solder somewhat in manner of windshield wiper. Each cycle of operation triggered by pulse from external robot. Equipment used wherever precise, automated soldering must be done to military specifications.

  9. Cathode for molten salt batteries

    DOEpatents

    Mamantov, Gleb; Marassi, Roberto

    1977-01-01

    A molten salt electrochemical system for battery applications comprises tetravalent sulfur as the active cathode material with a molten chloroaluminate solvent comprising a mixture of AlCl.sub.3 and MCl having a molar ratio of AlCl.sub.3 /MCl from greater than 50.0/50.0 to 80/20.

  10. Heat capacity of molten halides.

    PubMed

    Redkin, Alexander A; Zaikov, Yurii P; Korzun, Iraida V; Reznitskikh, Olga G; Yaroslavtseva, Tatiana V; Kumkov, Sergey I

    2015-01-15

    The heat capacities of molten salts are very important for their practical use. Experimental investigation of this property is challenging because of the high temperatures involved and the corrosive nature of these materials. It is preferable to combine experimental investigations with empirical relationships, which allows for the evaluation of the heat capacity of molten salt mixtures. The isobaric molar heat capacities of all molten alkali and alkaline-earth halides were found to be constant for each group of salts. The value depends on the number of atoms in the salt, and the molar heat capacity per atom is constant for all molten halide salts with the exception of the lithium halides. The molar heat capacities of molten halides do not change when the anions are changed.

  11. Heat capacity of molten halides.

    PubMed

    Redkin, Alexander A; Zaikov, Yurii P; Korzun, Iraida V; Reznitskikh, Olga G; Yaroslavtseva, Tatiana V; Kumkov, Sergey I

    2015-01-15

    The heat capacities of molten salts are very important for their practical use. Experimental investigation of this property is challenging because of the high temperatures involved and the corrosive nature of these materials. It is preferable to combine experimental investigations with empirical relationships, which allows for the evaluation of the heat capacity of molten salt mixtures. The isobaric molar heat capacities of all molten alkali and alkaline-earth halides were found to be constant for each group of salts. The value depends on the number of atoms in the salt, and the molar heat capacity per atom is constant for all molten halide salts with the exception of the lithium halides. The molar heat capacities of molten halides do not change when the anions are changed. PMID:25530462

  12. A chemically modified [alpha]-amylase with a molten-globule state has entropically driven enhanced thermal stability

    SciTech Connect

    Siddiqui, Khawar Sohail; Poljak, Anne; De Francisci, Davide; Guerriero, Gea; Pilak, Oliver; Burg, Dominic; Raftery, Mark J.; Parkin, Don M.; Trewhella, Jill; Cavicchioli, Ricardo

    2010-11-15

    The thermostability properties of TAA were investigated by chemically modifying carboxyl groups on the surface of the enzyme with AMEs. The TAA{sub MOD} exhibited a 200% improvement in starch-hydrolyzing productivity at 60 C. By studying the kinetic, thermodynamic and biophysical properties, we found that TAA{sub MOD} had formed a thermostable, MG state, in which the unfolding of the tertiary structure preceded that of the secondary structure by at least 20 C. The X-ray crystal structure of TAA{sub MOD} revealed no new permanent interactions (electrostatic or other) resulting from the modification. By deriving thermodynamic activation parameters of TAA{sub MOD}, we rationalised that thermostabilisation have been caused by a decrease in the entropy of the transition state, rather than being enthalpically driven. Far-UV CD shows that the origin of decreased entropy may have arisen from a higher helical content of TAA{sub MOD}. This study provides new insight into the intriguing properties of an MG state resulting from the chemical modification of TAA.

  13. Deconstructing time-resolved optical rotatory dispersion kinetic measurements of cytochrome c folding: from molten globule to the native state.

    PubMed

    Chen, Eefei; Kliger, David S

    2012-01-01

    The far-UV time-resolved optical rotatory dispersion (TRORD) technique has contributed significantly to our understanding of nanosecond secondary structure kinetics in protein folding and function reactions. For reduced cytochrome c, protein folding kinetics have been probed largely from the unfolded to the native state. Here we provide details about sample preparation and the TRORD apparatus and measurements for studying folding from a partly unfolded state to the native secondary structure conformation of reduced cytochrome c. PMID:22760330

  14. Evidence for a molten globule state in Cicer α-galactosidase induced by pH, temperature, and guanidine hydrochloride.

    PubMed

    Singh, Neelesh; Kumar, Reetesh; Jagannadham, M V; Kayastha, Arvind M

    2013-04-01

    Physiologically as well as industrially, α-galactosidases are very important enzymes, but very little is known about the stability and folding aspect of enzyme. In the present study, we have investigated the temperature, pH, and guanidine hydrochloride (GuHCl) induced unfolding of Cicer α-galactosidase using circular dichroism and fluorescence spectroscopy. Strong negative ellipticities at 208, 215, and 222 nm indicate the presence of both α and β structures in Cicer α-galactosidase and showed that its secondary structure belongs to α + β class of proteins with 31 % α-helicity. For Cicer α-galactosidase the emission maximum was found to be 345 nm which suggests that tryptophan residues are less exposed to solvent. However, at pH 2.0, protein showed blue-shift. This state of protein lacked activity but it retained significant secondary structure. Enhanced binding of ANS at pH 2.0 indicated significant unfolding and exposure of hydrophobic regions. The unfolded state of Cicer α-galactosidase showed a red-shift of 15 nm with a concomitant decrease in the fluorescence intensity. The enzyme maintained its native structure and full activity up to 40 °C; however, above this temperature, denaturation was observed. PMID:23446984

  15. Modern terrestrial analogues for the carbonate globules in Martian meteorite ALH84001.

    PubMed

    Kazmierczak, Józef; Kempe, Stephan

    2003-04-01

    Modern carbonate globules, located in cracks of submerged volcanic rocks and in calcareous pinnacles in alkaline (sodic) Lake Van, Turkey, appear to be analogues for the approximately 3.9 billion-year-old carbonate globules in Martian meteorite ALH84001. These terrestrial globules have similar diameters and are chemically and mineralogically zoned. Furthermore, they display surface and etching structures similar to those described from ALH84001, which were interpreted as fossilized microbial forms. These terrestrial carbonates formed at low temperatures where Ca-rich groundwaters enter the lake. Chemical, mineralogical, microbiological, and biomolecular methods were used in an attempt to decipher the process responsible for the genesis of these structures. Although the exact mode of formation of Lake Van carbonates remains an enigma, their similarity to the Martian globules indicates that the ALH84001 carbonates may have formed in similar setting on ancient Mars. PMID:12712250

  16. The endoplasmic reticulum and casein-containing vesicles contribute to milk fat globule membrane.

    PubMed

    Honvo-Houéto, Edith; Henry, Céline; Chat, Sophie; Layani, Sarah; Truchet, Sandrine

    2016-10-01

    During lactation, mammary epithelial cells secrete huge amounts of milk from their apical side. The current view is that caseins are secreted by exocytosis, whereas milk fat globules are released by budding, enwrapped by the plasma membrane. Owing to the number and large size of milk fat globules, the membrane surface needed for their release might exceed that of the apical plasma membrane. A large-scale proteomics analysis of both cytoplasmic lipid droplets and secreted milk fat globule membranes was used to decipher the cellular origins of the milk fat globule membrane. Surprisingly, differential analysis of protein profiles of these two organelles strongly suggest that, in addition to the plasma membrane, the endoplasmic reticulum and the secretory vesicles contribute to the milk fat globule membrane. Analysis of membrane-associated and raft microdomain proteins reinforces this possibility and also points to a role for lipid rafts in milk product secretion. Our results provide evidence for a significant contribution of the endoplasmic reticulum to the milk fat globule membrane and a role for SNAREs in membrane dynamics during milk secretion. These novel aspects point to a more complex model for milk secretion than currently envisioned.

  17. Isolated milk fat globules as substrate for lipoprotein lipase: study of factors relevant to spontaneous lipolysis in milk

    SciTech Connect

    Sundheim, G.; Bengtsson-Olivecrona, G.

    1987-03-01

    Fat globules isolated from normal and from spontaneous milk samples were compared as substrates for purified lipoprotein lipase. Only slight differences were observed. Fat globules isolated from fresh warm milk were almost resistant to lipolysis. This included globules from milk prone to spontaneous lipolysis. Cooling made the globules accessible to rapid lipolysis even if they were from normal milk. Rewarming the fat globules did not reverse the process. Maximum rate of lipolysis (after rewarming) required fat globules be stored at 10/sup 0/C or below for 5 to 10 h. Lipolysis at 4/sup 0/C usually started after a lag time of 3 to 5 h, but with fat globules from spontaneous milk the lag time was shorter. Fat globules isolated from cold milk were a poor substrate at 4/sup 0/C but were lipolyzed when warmed. When /sup 125/I-labeled lipase was added to fresh warm milk, some of the lipase bound to the milk fat globules but it caused little lipolysis. Binding increased after cooling, as did lipolysis. Both binding of lipase and lipolysis were impeded by the presence of skim milk. Another way to make fat globules isolated from fresh warm milk susceptible to lipolysis was to treat them with chemicals known to remove proteins.

  18. Molten salt techniques. Volume 2

    SciTech Connect

    Gale, R.J.; Lovering, D.G.

    1984-01-01

    This is the second volume in a series addressing the practical aspects of molten salt research. The book covers experiments with alkali metal carbonates, oxides, silicates, phosphates and borates. Additional sections cover molten salt spectroscopy, electrochemistry, and automated admittance spectroscopy of the semiconductor/molten salt electrolyte interface. Particular emphasis is given to safety considerations for working with these high temperature, often corrosive materials. Planning of experiments is of interest, and several experiments are described. Attention is given to the selection of materials to be used in this research, including the purification of the salts themselves, and the requirements for laboratory apparatus.

  19. The molten salt reactor adventure

    SciTech Connect

    MacPherson, H.G.

    1985-08-01

    A personal history of the development of molten salt reactors in the United States is presented. The initial goal was an aircraft propulsion reactor, and a molten fluoride-fueled Aircraft Reactor Experiment was operated at Oak Ridge National Laboratory in 1954. In 1956, the objective shifted to civilian nuclear power, and reactor concepts were developed using a circulating UF4-ThF4 fuel, graphite moderator, and Hastelloy N pressure boundary. The program culminated in the successful operation of the Molten Salt Reactor Experiment in 1965 to 1969. By then the Atomic Energy Commission's goals had shifted to breeder development; the molten salt program supported on-site reprocessing development and study of various reactor arrangements that had potential to breed. Some commercial and foreign interest contributed to the program which, however, was terminated by the government in 1976. The current status of the technology and prospects for revived interest are summarized.

  20. Electrolysis of a molten semiconductor.

    PubMed

    Yin, Huayi; Chung, Brice; Sadoway, Donald R

    2016-08-24

    Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb2S3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across the cell. As opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO2, CO and SO2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides.

  1. Electrolysis of a molten semiconductor

    NASA Astrophysics Data System (ADS)

    Yin, Huayi; Chung, Brice; Sadoway, Donald R.

    2016-08-01

    Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb2S3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across the cell. As opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO2, CO and SO2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides.

  2. Carbonate Globules from Spitsbergen, Norway: Terrestrial Analogs of the Carbonates in Martian Meteorite ALH84001?

    NASA Technical Reports Server (NTRS)

    De, Subarnarek; Bunch, Ted; Treiman, Allan H.; Amundsen, Hans E. F.; Blake, David F.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Pleistocene volcanic centers in NW Spitsbergen, Norway host one of the world's richest occurrences of mantle xenoliths. The xenoliths comprise varieties of spinel lherzolites and pyroxenites. Some of these xenoliths (and their host basalts) contain 10-100 micrometer globules of ankedtic-magnesitic carbonates (AMC). In composition, mineralogy and petrology the AMC globules from Spitsbergen are strikingly similar to the carbonate globules in ALH84001. The AMC globules occur within interstitial quenched glass and as fracture fillings, although we have not seen replacement fabrics analogous to carbonate rosettes replacing glass in ALH84001. Siderite/ankerite forms the core of these concentrically zoned globules while rims are predominantly magnesite. Clay minerals can occasionally be found within and around the globules. Aside from the clay minerals, the principal mineralogical difference between the AMCs and the ALH84001 carbonate rosettes is the presence of concentrated zones of nanophase magnetite in the rosettes, notably absent in the AMCs. However, carbonate globules containing nanophase magnetite have been produced inorganically by hydrothermal precipitation of carbonates and subsequent heating. We heated Spitsbergen AMC at 585 C in a reducing atmosphere to determine whether magnetite could be produced. Optical micrographs of the heated Spitsbergen AMC show dark concentric zones within the AMC. High resolution SEM images of those areas reveal 150-200 nm euhedral crystals that exhibit various morphologies including octahedra and elongated prisms. EDS analyses of areas where the crystals occur contain Fe, O, and minor Si, and P. However, the probe integrates over volumes of material, which also include the surrounding matrix. We have begun TEM observations of both the heated and unheated Spitsbergen AMC to characterize the microstructures of the carbonates, establish the presence/absence of magnetite and determine the relationship of the clay minerals to the

  3. Batteries using molten salt electrolyte

    DOEpatents

    Guidotti, Ronald A.

    2003-04-08

    An electrolyte system suitable for a molten salt electrolyte battery is described where the electrolyte system is a molten nitrate compound, an organic compound containing dissolved lithium salts, or a 1-ethyl-3-methlyimidazolium salt with a melting temperature between approximately room temperature and approximately 250.degree. C. With a compatible anode and cathode, the electrolyte system is utilized in a battery as a power source suitable for oil/gas borehole applications and in heat sensors.

  4. A novel infant milk formula concept: Mimicking the human milk fat globule structure.

    PubMed

    Gallier, Sophie; Vocking, Karin; Post, Jan Andries; Van De Heijning, Bert; Acton, Dennis; Van Der Beek, Eline M; Van Baalen, Ton

    2015-12-01

    Human milk (HM) provides all nutrients to support an optimal growth and development of the neonate. The composition and structure of HM lipids, the most important energy provider, have an impact on the digestion, uptake and metabolism of lipids. In HM, the lipids are present in the form of dispersed fat globules: large fat droplets enveloped by a phospholipid membrane. Currently, infant milk formula (Control IMF) contains small fat droplets primarily coated by proteins. Recently, a novel IMF concept (Concept IMF) was developed with a different lipid architecture, Nuturis(®), comprising large fat droplets with a phospholipid coating. Confocal laser scanning microscopy (CLSM), with appropriate fluorescent probes, and transmission electron microscopy were used to determine and compare the interfacial composition and structure of HM fat globules, Concept IMF fat droplets and Control IMF fat droplets. The presence of a trilayer-structured HM fat globule membrane, composed of phospholipids, proteins, glycoproteins and cholesterol, was confirmed; in addition exosome-like vesicles are observed within cytoplasmic crescents. The Control IMF fat droplets had a thick protein-only interface. The Concept IMF fat droplets showed a very thin interface composed of a mixture of phospholipids, proteins and cholesterol. Furthermore, the Concept IMF contained fragments of milk fat globule membrane, which has been suggested to have potential biological functions in infants. By mimicking more closely the structure and composition of HM fat globules, this novel IMF concept with Nuturis(®) may have metabolic and digestive properties that are more similar to HM compared to Control IMF.

  5. Molten metal injector system and method

    DOEpatents

    Meyer, Thomas N.; Kinosz, Michael J.; Bigler, Nicolas; Arnaud, Guy

    2003-04-01

    Disclosed is a molten metal injector system including a holder furnace, a casting mold supported above the holder furnace, and a molten metal injector supported from a bottom side of the mold. The holder furnace contains a supply of molten metal having a metal oxide film surface. The bottom side of the mold faces the holder furnace. The mold defines a mold cavity for receiving the molten metal from the holder furnace. The injector projects into the holder furnace and is in fluid communication with the mold cavity. The injector includes a piston positioned within a piston cavity defined by a cylinder for pumping the molten metal upward from the holder furnace and injecting the molten metal into the mold cavity under pressure. The piston and cylinder are at least partially submerged in the molten metal when the holder furnace contains the molten metal. The cylinder further includes a molten metal intake for receiving the molten metal into the piston cavity. The molten metal intake is located below the metal oxide film surface of the molten metal when the holder furnace contains the molten metal. A method of injecting molten metal into a mold cavity of a casting mold is also disclosed.

  6. Goat α(s1)-casein genotype affects milk fat globule physicochemical properties and the composition of the milk fat globule membrane.

    PubMed

    Cebo, C; Lopez, C; Henry, C; Beauvallet, C; Ménard, O; Bevilacqua, C; Bouvier, F; Caillat, H; Martin, P

    2012-11-01

    Milk fat secretion is a complex process that initiates in the endoplasmic reticulum of the mammary epithelial cell by the budding of lipid droplets. Lipid droplets are finally released as fat globules in milk enveloped by the apical plasma membrane of the mammary epithelial cell. The milk fat globule membrane (MFGM) thus comprises membrane-specific proteins and polar lipids (glycerophospholipids and sphingolipids) surrounding a core of neutral lipids (mainly triacylglycerols and cholesterol esters). We have recently described major proteins of the MFGM in the goat and we have highlighted prominent differences between goats and bovine species, especially regarding lactadherin, a major MFGM protein. Here, we show that, in the goat species, the well-documented genetic polymorphism at the α(s1)-casein (CSN1S1) locus affects both structure and composition of milk fat globules. We first evidenced that both milk fat globule size and ζ-potential are related to the α(s1)-casein genotype. At midlactation, goats displaying strong genotypes for α(s1)-casein (A/A goats) produce larger fat globules than goats with a null genotype at the CSN1S1 locus (O/O goats). A linear relationship (R(2)=0.75) between fat content (g/kg) in the milk and diameter of fat globules (μm) was established. Moreover, we found significant differences with regard to MFGM composition (including both polar lipids and MFGM proteins) from goats with extreme genotype at the CSN1S1 locus. At midlactation, the amount of polar lipids is significantly higher in the MFGM from goats with null genotypes for α(s1)-casein (O/O goats; 5.97±0.11mg/g of fat; mean ± standard deviation) than in the MFGM from goats with strong genotypes for α(s1)-casein (A/A goats; 3.96±0.12mg/g of fat; mean ± standard deviation). Two MFGM-associated proteins, namely lactadherin and stomatin, are also significantly upregulated in the MFGM from goats with null genotype for α(s1)-casein at early lactation. Our findings are

  7. Organic Globules in the Tagish Lake Meteorite: Remnants of the Protosolar Disk

    NASA Astrophysics Data System (ADS)

    Nakamura-Messenger, Keiko; Messenger, Scott; Keller, Lindsay P.; Clemett, Simon J.; Zolensky, Michael E.

    2006-12-01

    Coordinated transmission electron microscopy and isotopic measurements of organic globules in the Tagish Lake meteorite shows that they have elevated ratios of nitrogen-15 to nitrogen-14 (1.2 to 2 times terrestrial) and of deuterium to hydrogen (2.5 to 9 times terrestrial). These isotopic anomalies are indicative of mass fractionation during chemical reactions at extremely low temperatures (10 to 20 kelvin), characteristic of cold molecular clouds and the outer protosolar disk. The globules probably originated as organic ice coatings on preexisting grains that were photochemically processed into refractory organic matter. The globules resemble cometary carbon, hydrogen, oxygen, and nitrogen (CHON) particles, suggesting that such grains were important constituents of the solar system starting materials.

  8. Organic globules in the Tagish Lake meteorite: remnants of the protosolar disk.

    PubMed

    Nakamura-Messenger, Keiko; Messenger, Scott; Keller, Lindsay P; Clemett, Simon J; Zolensky, Michael E

    2006-12-01

    Coordinated transmission electron microscopy and isotopic measurements of organic globules in the Tagish Lake meteorite shows that they have elevated ratios of nitrogen-15 to nitrogen-14 (1.2 to 2 times terrestrial) and of deuterium to hydrogen (2.5 to 9 times terrestrial). These isotopic anomalies are indicative of mass fractionation during chemical reactions at extremely low temperatures (10 to 20 kelvin), characteristic of cold molecular clouds and the outer protosolar disk. The globules probably originated as organic ice coatings on preexisting grains that were photochemically processed into refractory organic matter. The globules resemble cometary carbon, hydrogen, oxygen, and nitrogen (CHON) particles, suggesting that such grains were important constituents of the solar system starting materials.

  9. ORIGIN OF ORGANIC GLOBULES IN METEORITES: LABORATORY SIMULATION USING AROMATIC HYDROCARBONS

    SciTech Connect

    Saito, Midori; Kimura, Yuki

    2009-10-01

    Analogs of organic hollow globules, which have been found in carbonaceous chondrite meteorites and interplanetary dust particles, were synthesized in our laboratory from benzene and anthracene using plasma. Our results suggest that organic globules could be made from aromatic rings in circumstellar envelopes around evolved stars. The hollow interior could be formed by coagulation of vacancies, formed by electronic excitation and/or knock-out of carbon atoms following irradiation by plasma particles such as protons and He{sup +} ions. This experimental result suggests that organic globules are possibly the final products in the evolution of carbonaceous matter from acetylene and benzene to polycyclic aromatic hydrocarbons in ejecta gas from evolved stars.

  10. The RING domain of the scaffold protein Ste5 adopts a molten globular character with high thermal and chemical stability.

    PubMed

    Walczak, Michal J; Samatanga, Brighton; van Drogen, Frank; Peter, Matthias; Jelesarov, Ilian; Wider, Gerhard

    2014-01-27

    Ste5 is a scaffold protein that controls the pheromone response of the MAP-kinase cascade in yeast cells. Upon pheromone stimulation, Ste5 (through its RING-H2 domain) interacts with the β and γ subunits of an activated heterodimeric G protein and promotes activation of the MAP-kinase cascade. With structural and biophysical studies, we show that the Ste5 RING-H2 domain exists as a molten globule under native buffer conditions, in yeast extracts, and even in denaturing conditions containing urea (7 M). Furthermore, it exhibits high thermal stability in native conditions. Binding of the Ste5 RING-H2 domain to the physiological Gβ/γ (Ste4/Ste18) ligand is accompanied by a conformational transition into a better folded, more globular structure. This study reveals novel insights into the folding mechanism and recruitment of binding partners by the Ste5 RING-H2 domain. We speculate that many RING domains may share a similar mechanism of substrate recognition and molten-globule-like character.

  11. The RING domain of the scaffold protein Ste5 adopts a molten globular character with high thermal and chemical stability.

    PubMed

    Walczak, Michal J; Samatanga, Brighton; van Drogen, Frank; Peter, Matthias; Jelesarov, Ilian; Wider, Gerhard

    2014-01-27

    Ste5 is a scaffold protein that controls the pheromone response of the MAP-kinase cascade in yeast cells. Upon pheromone stimulation, Ste5 (through its RING-H2 domain) interacts with the β and γ subunits of an activated heterodimeric G protein and promotes activation of the MAP-kinase cascade. With structural and biophysical studies, we show that the Ste5 RING-H2 domain exists as a molten globule under native buffer conditions, in yeast extracts, and even in denaturing conditions containing urea (7 M). Furthermore, it exhibits high thermal stability in native conditions. Binding of the Ste5 RING-H2 domain to the physiological Gβ/γ (Ste4/Ste18) ligand is accompanied by a conformational transition into a better folded, more globular structure. This study reveals novel insights into the folding mechanism and recruitment of binding partners by the Ste5 RING-H2 domain. We speculate that many RING domains may share a similar mechanism of substrate recognition and molten-globule-like character. PMID:24356903

  12. [Milk fat globules, as determinants of the nutritional and biological value of goat milk].

    PubMed

    Skidan, I N; Gulyaev, A E; Kaznacheev, K S

    2015-01-01

    This review summarizes the most complete information on such fundamentally important quality parameters of goat milk as the cellular composition of somatic cells and the structure of cytoplasmic debris in milk. It also focuses on the characterization of an essential component of the energetic value and nutritional content of milk--milk fat globules and milk fat globule membranes. The survey also clarifies some of the terms and meanings of physiological processes associated with the formation of the milk of various ruminants and breast milk. PMID:26841561

  13. Olivine and Carbonate Globules in ALH84001: A Terrestrial Analog, and Implications for Water on Mars

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    2005-01-01

    Carbonate globules in ALH84001 are associated with small olivine grains an unexpected finding because the olivines equilibrated at high T while the carbonate is chemically zoned and unequilibrated. A possible explanation comes from a terrestrial analog on Spitsbergen (Norway), where some carbonate globules grew in cavities left by aqueous dissolution of olivine. For ALH84001, the same process may have acted, with larger olivines dissolved out and smaller ones shielded inside orthopyroxene. Carbonate would have been deposited in holes where the olivine had been. Later shocks crushed remaining void space, and mobilized feldspathic glass around the carbonates.

  14. Dark Cloud and Globule Distribution for Galactic Longitudes 230 to 360 Degrees

    NASA Technical Reports Server (NTRS)

    Feitzinger, J. V.; Stuewe, J. A.

    1984-01-01

    A catalogue of dark nebulae and globules was compiled from a study of the ESO-B and SRC-J sky atlas for galactic longitudes 230 deg 1 360 deg. This catalogue closes the great southern gap open since the work of Lynds (1962). Listed were 489 dark nebulae and 311 globules. The catalogue contains positions, sizes, opacities, and the van den Bergh classification on the filamentary morphology of dark clouds. Statistics are presented concerning the northern and southern distributions and sizes of the nebulae.

  15. Ceramics for Molten Materials Transfer

    NASA Technical Reports Server (NTRS)

    Standish, Evan; Stefanescu, Doru M.; Curreri, Peter A.

    2009-01-01

    The paper reviews the main issues associated with molten materials transfer and handling on the lunar surface during the operation of a hig h temperature electrowinning cell used to produce oxygen, with molten iron and silicon as byproducts. A combination of existing technolog ies and purposely designed technologies show promise for lunar exploi tation. An important limitation that requires extensive investigation is the performance of refractory currently used for the purpose of m olten metal containment and transfer in the lunar environment associa ted with electrolytic cells. The principles of a laboratory scale uni t at a scale equivalent to the production of 1 metric ton of oxygen p er year are introduced. This implies a mass of molten materials to be transferred consistent with the equivalent of 1kg regolithlhr proces sed.

  16. Supported molten-metal catalysts

    DOEpatents

    Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

    2001-01-01

    An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (<600.degree. C.), inexpensive, and abundant metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

  17. Coil–globule transition of a polymer involved in excluded-volume interactions with macromolecules

    SciTech Connect

    Odagiri, Kenta; Seki, Kazuhiko

    2015-10-07

    Polymers adopt extended coil and compact globule states according to the balance between entropy and interaction energies. The transition of a polymer between an extended coil state and compact globule state can be induced by changing thermodynamic force such as temperature to alter the energy/entropy balance. Previously, this transition was theoretically studied by taking into account the excluded-volume interaction between monomers of a polymer chain using the partition function. For binary mixtures of a long polymer and short polymers, the coil-globule transition can be induced by changing the concentration of the shorter polymers. Here, we investigate the transition caused by short polymers by generalizing the partition function of the long polymer to include the excluded-volume effect of short polymers. The coil-globule transition is studied as a function of the concentration of mixed polymers by systematically varying Flory’s χ-parameters. We show that the transition is caused by the interplay between the excluded-volume interaction and the dispersion state of short polymers in the solvent. We also reveal that the same results can be obtained by combining the mixing entropy and elastic energy if the volume of a long polymer is properly defined.

  18. Na-Fe-Phosphate Globules in Impact Metal-Troilite Associations of Chelyabinsk Meteorite

    NASA Astrophysics Data System (ADS)

    Sharygin, V. V.; Karmanov, N. S.; Podgornykh, N. M.

    2016-08-01

    Multi- and monophase phosphate globules have been found in the impact metal-troilite aggregates of the Chelyabinsk chondrite. Their phase composition varies and they contain galileiite, sarcopside, graftonite and Na-Fe-phosphate Na2(Fe,Mn)5(PO4)4.

  19. Enzymic characteristics of fat globule membranes from bovine colostrum and bovine milk

    PubMed Central

    1977-01-01

    Fat globule membranes have been isolated from bovine colostrum and bovine milk by the dispersion of the fat in sucrose solutions at 4 degrees C and fractionation by centrifugation through discontinuous sucrose gradients. The morphology and enzymic characteristics of the separated fractions were examined. Fractions comprising a large proportion of the total extracted membrane were thus obtained having high levels of the Golgi marker enzymes UDP-galactose N- acetylglucosamine beta-4-galactosyltransferase and thiamine pyrophosphatase. A membrane-derived form of the galactosyltransferase has been solubilized from fat and purified to homogeneity. This enzyme is larger in molecular weight than previously studied soluble galactosyltransferases, but resembles in size the galactosyltransferase of lactating mammary Golgi membranes. In contrast, when fat globule membranes were prepared by traditional procedures, which involved washing the fat at higher temperatures, before extraction, galactosyltransferase was not present in the membranes, having been released into supernatant fractions, When the enzyme released by this procedure was partially purified and examined by gel filtration, it was found to be of a degraded form resembling in size the soluble galactosyltransferase of milk. The release is therefore attributed to the action of proteolytic enzymes. Our observations contrast with previous biochemical studies which suggested that Golgi membranes do not contribute to the milk fat globule membrane. They are, however, consistent with electron microscope studies of the fat secretion process, which indicate that secretory vesicle membranes, derived from the Golgi apparatus, may provide a large proportion of the fat globule membrane. PMID:402369

  20. Polymer globule with fractal properties caused by intramolecular nanostructuring and spatial constrains.

    PubMed

    Glagoleva, Anna A; Vasilevskaya, Valentina V; Khokhlov, Alexei R

    2016-06-21

    By means of computer simulation, we studied macromolecules composed of N dumbbell amphiphilic monomer units with attractive pendant groups. In poor solvents, these macromolecules form spherical globules that are dense in the case of short chains (the gyration radius RG∼N(1/3)), or hollow inside and obey the RG∼N(1/2) law when the macromolecules are sufficiently long. Due to the specific intramolecular nanostructuring, the vesicle-like globules of long amphiphilic macromolecules posses some properties of fractal globules, by which they (i) could demonstrate the same scaling statistics for the entire macromolecule and for short subchains with m monomer units and (ii) possess a specific territorial structure. Within a narrow slit, the globule loses its inner cavity, takes a disk-like shape and scales as N(1/2) for much shorter macromolecules. However, the field of end-to-end distance r(m) ∼m(1/2) dependence for subchains becomes visibly smaller. The results obtained were compared with the homopolymer case. PMID:27198966

  1. About iron globules formed at cooling of iron-contained plasma

    NASA Astrophysics Data System (ADS)

    Bulina, N. V.; Gromyko, A. I.; Bondarenko, G. V.; Marachevsky, A. V.; Chekanova, L. A.; Prokof'ev, D. E.; Churilov, G. N.

    2006-12-01

    This paper is devoted to the investigation of iron globules that are formed during cooling of the iron-carbon-helium plasma and as a result of destruction of a natural ball lightning. Scanning electron microscopy, X-ray fluorescence, X-ray diffraction, and ferromagnetic resonance investigations were carried out. The magnetization values of the samplers were determined.

  2. Developmental changes in the milk fat globule membrane proteome during the transition from colostrum to milk

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shotgun Proteomics, using amine-reactive isobaric tags (iTRAQ) was used to quantify protein changes in milk fat globule membranes (MFGM) that were isolated from day 1 colostrum and compared to MFGM from day 7 milk. Eight Holstein cows were randomly assigned to 2 groups of 4 cow sample pools for a s...

  3. Developmental changes in milk fat globule membrane proteome expression during the transition from colostrum to milk

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shotgun Proteomics, using amine-reactive isobaric tags (iTRAQ) was used to quantify protein changes in milk fat globule membranes (MFGM) that were isolated from day 1 colostrum and compared to MFGM from day 7 milk. Eight Holstein cows were randomly assigned to 2 groups of 4 cow sample pools for a s...

  4. Electrolysis of a molten semiconductor.

    PubMed

    Yin, Huayi; Chung, Brice; Sadoway, Donald R

    2016-01-01

    Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb2S3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across the cell. As opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO2, CO and SO2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides. PMID:27553525

  5. Stability of Molten Core Materials

    SciTech Connect

    Layne Pincock; Wendell Hintze

    2013-01-01

    The purpose of this report is to document a literature and data search for data and information pertaining to the stability of nuclear reactor molten core materials. This includes data and analysis from TMI-2 fuel and INL’s LOFT (Loss of Fluid Test) reactor project and other sources.

  6. Electrolysis of a molten semiconductor

    PubMed Central

    Yin, Huayi; Chung, Brice; Sadoway, Donald R.

    2016-01-01

    Metals cannot be extracted by electrolysis of transition-metal sulfides because as liquids they are semiconductors, which exhibit high levels of electronic conduction and metal dissolution. Herein by introduction of a distinct secondary electrolyte, we reveal a high-throughput electro-desulfurization process that directly converts semiconducting molten stibnite (Sb2S3) into pure (99.9%) liquid antimony and sulfur vapour. At the bottom of the cell liquid antimony pools beneath cathodically polarized molten stibnite. At the top of the cell sulfur issues from a carbon anode immersed in an immiscible secondary molten salt electrolyte disposed above molten stibnite, thereby blocking electronic shorting across the cell. As opposed to conventional extraction practices, direct sulfide electrolysis completely avoids generation of problematic fugitive emissions (CO2, CO and SO2), significantly reduces energy consumption, increases productivity in a single-step process (lower capital and operating costs) and is broadly applicable to a host of electronically conductive transition-metal chalcogenides. PMID:27553525

  7. MOLTEN FLUORIDE NUCLEAR REACTOR FUEL

    DOEpatents

    Barton, C.J.; Grimes, W.R.

    1960-01-01

    Molten-salt reactor fuel compositions consisting of mixtures of fluoride salts are reported. In its broadest form, the composition contains an alkali fluoride such as sodium fluoride, zirconium tetrafluoride, and a uranium fluoride, the latter being the tetrafluoride or trifluoride or a mixture of the two. An outstanding property of these fuel compositions is a high coeffieient of thermal expansion which provides a negative temperature coefficient of reactivity in reactors in which they are used.

  8. Molten carbonate fuel cell matrices

    DOEpatents

    Vogel, Wolfgang M.; Smith, Stanley W.

    1985-04-16

    A molten carbonate fuel cell including a cathode electrode of electrically conducting or semiconducting lanthanum containing material and an electrolyte containing matrix of an electrically insulating lanthanum perovskite. In addition, in an embodiment where the cathode electrode is LaMnO.sub.3, the matrix may include LaAlO.sub.3 or a lithium containing material such as LiAlO.sub.2 or Li.sub.2 TiO.sub.3.

  9. Partially molten magma ocean model

    SciTech Connect

    Shirley, D.N.

    1983-02-15

    The properties of the lunar crust and upper mantle can be explained if the outer 300-400 km of the moon was initially only partially molten rather than fully molten. The top of the partially molten region contained about 20% melt and decreased to 0% at 300-400 km depth. Nuclei of anorthositic crust formed over localized bodies of magma segregated from the partial melt, then grew peripherally until they coverd the moon. Throughout most of its growth period the anorthosite crust floated on a layer of magma a few km thick. The thickness of this layer is regulated by the opposing forces of loss of material by fractional crystallization and addition of magma from the partial melt below. Concentrations of Sr, Eu, and Sm in pristine ferroan anorthosites are found to be consistent with this model, as are trends for the ferroan anorthosites and Mg-rich suites on a diagram of An in plagioclase vs. mg in mafics. Clustering of Eu, Sr, and mg values found among pristine ferroan anorthosites are predicted by this model.

  10. Metals Electroprocessing in Molten Salts

    NASA Technical Reports Server (NTRS)

    Sadoway, D. R.

    1985-01-01

    The present study seeks to explain the poor quality of solid electrodeposits in molten salts through a consideration of the effects of fluid flow of the electrolyte. Transparent cells allow observation of electrolyte circulation by a laser schlieren optical technique during the electrodeposition of solid zinc from the molten salt electrolyte, ZnCl2 - LiCl-KCl. Experimental variables are current, density, electrolyte composition, and cell geometry. Based on the results of earlier electrodeposition studies as well as reports in the literature, these parameters are identified as having the primary influence on cell performance and deposit quality. Experiments are conducted to measure the fluid flow patterns and the electrochemical cell characteristics, and to correlate this information with the morphology of the solid electrodeposit produced. Specifically, cell voltage, cell current, characteristic time for dendrite evolution, and dendrite growth directions are noted. Their relationship to electrolyte flow patterns and the morphology of the resulting electrodeposit are derived. Results to date indicate that laser schlieren imaging is capable of revealing fluid flow patterns in a molten salt electrolyte.

  11. Thermal and ignition type steam explosions of single drops of molten aluminum

    SciTech Connect

    Nelson, L.S.; Duda, P.M.; Hyndman, D.A.; Allison, D.K.; Hyder, M.L.

    1995-07-01

    Seventeen steam explosion experiments were performed with 2 to 10 g drops of molten, high-purity Al. Seven were successfully initiated with underwater exploding bridgewires. At melt release temperatures up to 1400{degrees}C (1673 K) only moderate thermal-type explosions occurred that produced bubbles with volumes up to approximately 1 L. Bubble growth intensified in the melt temperature range 1400-1525{degrees}C (1673--1798 K) as threshold ignition of Al set in. In this range, one of the explosions emitted a flash of light and generated a bubble that grew very rapidly to approximately 14 L, broke through the water surface, and destroyed the test chamber. We attribute the behavior of this latter bubble, which grew as fast as one produced by the underwater firing of a 0.6 g explosive detonator, to an ignition-type steam explosion. Aluminum oxides could not be detected visually in the debris recovered from either typical thermal-type or the ignition-type explosions, and only traces could be detected by X-ray diffraction. In the ignition-type explosion, it is possible however that some oxidic material, probably the smaller particles, was lost during the flooding that occurred as the chamber failed. Both bubble analyses and the absence of appreciable oxide in the debris suggest that the ignition-type steam explosion was not very efficient, probably involving the combustion of only a small fraction of the original molten aluminum globule.

  12. Immunocytochemical Evidence for Golgi Vesicle Involvement in Milk Fat Globule Secretion.

    PubMed

    Wooding, F B Peter; Sargeant, Timothy J

    2015-12-01

    The exact mechanism of secretion of the milk fat globule (MFG) from the mammary secretory cell is still controversial. We have previously suggested close involvement of Golgi vesicles in this process. This paper provides direct immunocytochemical evidence that butyrophilin is present in the Golgi stack and vesicles in ovine and caprine mammary glands. We suggest that it is the butyrophilin in the Golgi vesicle membrane that forms the specific association with the adipophilin on the lipid surface in the cytoplasm. Exocytosis of the associated Golgi vesicle will then initiate the process of MFG secretion. Further exocytosis of associated Golgi vesicles will continue and complete the process. Areas of the plasmalemma that have butyrophilin delivered by previous non-lipid associated Golgi exocytoses may also contribute to the process of forming the milk fat globule membrane (MFGM). PMID:26374828

  13. Comparative proteomics of milk fat globule membrane in different species reveals variations in lactation and nutrition.

    PubMed

    Lu, Jing; Wang, Xinyu; Zhang, Weiqing; Liu, Lu; Pang, Xiaoyang; Zhang, Shuwen; Lv, Jiaping

    2016-04-01

    In present study, 312, 554, 175 and 143 proteins were identified and quantified by label-free quantitative proteomics in human, cow, goat and yak milk fat globule membrane (MFGM), respectively. Fifty proteins involved in vesicle mediate transport and milk fat globule secretion were conserved among species. Moreover, proteins involved in lipid synthesis and secretion (xanthine dehydrogenase/oxidase, stomatin and CD36), showed different expression pattern and the host defense proteins exhibited various profiles within species. Notably, the content and activity of lipid catabolic enzymes were significantly higher in human MFGM, which could be indicative of the superior fat utilization in breast fed infants. Our findings unraveled the significant differences in protein composition of human milk and conventionally used substitutes of it. The in-depth study of lipid metabolic enzymes in human MFGM will probably contribute to the improvement of the fat utilization through modulation of lipid catabolic enzymes in infant formula.

  14. Optical Coherence Tomography Findings in Anterior Chamber Ointment Globule after Phacoemulsification

    PubMed Central

    Mansour, Ahmad M.; Haddad, Randa S.; Salti, Haytham I.; Habbal, Zuhair

    2015-01-01

    We present 2 cases of anterior chamber ointment with evidence of progressive endothelial cell loss. In both cases, an anterior segment optical coherence tomography (OCT) was similar to an OCT of a tobramycin-dexamethasone ointment placed on a pen tip. An anterior segment OCT also demonstrated the direct contact of the globule with the corneal endothelium. A gas chromatography/mass spectrometry analysis documented the similarity to tobramycin-dexamethasone ointment in 1 case. Anterior segment OCT can help in confirming the diagnosis. Corneal endothelial injury is a continuous process, and its clinical manifestation is related to the size of the globule, the initial endothelium count, and the duration of ointment contact, which is related to supine positioning. It is advisable to avoid ointments in the immediate postoperative period, especially in corneal wounds larger than 3 mm. PMID:26955351

  15. Comparative proteomics of milk fat globule membrane in different species reveals variations in lactation and nutrition.

    PubMed

    Lu, Jing; Wang, Xinyu; Zhang, Weiqing; Liu, Lu; Pang, Xiaoyang; Zhang, Shuwen; Lv, Jiaping

    2016-04-01

    In present study, 312, 554, 175 and 143 proteins were identified and quantified by label-free quantitative proteomics in human, cow, goat and yak milk fat globule membrane (MFGM), respectively. Fifty proteins involved in vesicle mediate transport and milk fat globule secretion were conserved among species. Moreover, proteins involved in lipid synthesis and secretion (xanthine dehydrogenase/oxidase, stomatin and CD36), showed different expression pattern and the host defense proteins exhibited various profiles within species. Notably, the content and activity of lipid catabolic enzymes were significantly higher in human MFGM, which could be indicative of the superior fat utilization in breast fed infants. Our findings unraveled the significant differences in protein composition of human milk and conventionally used substitutes of it. The in-depth study of lipid metabolic enzymes in human MFGM will probably contribute to the improvement of the fat utilization through modulation of lipid catabolic enzymes in infant formula. PMID:26593540

  16. A protective effect of milk fat globule EGF factor VIII (MFG-E8) on the spontaneous fusion of milk fat globules in breast milk.

    PubMed

    Yasueda, Takehiko; Oshima, Kenzi; Nakatani, Hajime; Tabuchi, Kanji; Nadano, Daita; Matsuda, Tsukasa

    2015-07-01

    Lipid droplets synthesized in mammary epithelial cells are secreted into breast milk by the budding-off mechanism. The milk lipids, termed mik fat globules (MFGs), are surrounded with the cell plasma membrane and contain various membrane proteins, including milk fat globule epidermal growth factor (EGF)-factor VIII (MFG-E8), on their surface. We report here that the MFGs in the milk of MFG-E8-deficient mice fused each other and turned into abnormally large size of lipid droplets within ∼48 h after being secreted into mammary alveolar lumen in situ or being incubated at 37°C in vitro. This biophysical degeneration of MFGs in the MFG-E8-deficient milk was efficiently rescued in vitro by adding the milk serum of wild-type mice, isolated MFG-E8 or annexin V. Moreover, addition of ethylenediaminetetraacetic acid (30 mM) also protected the MFG fusion remarkably in vitro. In addition, bovine MFGs also fused each other when isolated from milk serum, and the fusion was inhibited by adding isolated MFG-E8 or mouse milk serum, but not the milk serum of MFG-E8-deficient mice. MFG-E8 in breast milk may mask the phosphatidylserine exposed on the surface of MFGs with time after secretion and thereby suppress the membrane fusion among MFGs resulting in the enlargement of MFGs in the breast milk. PMID:25661589

  17. A Spitzer Survey of an Isolated Globule: DC314.8-5.1

    NASA Astrophysics Data System (ADS)

    Shenoy, Sachindev S.; Whittet, D. C. B.; Pendleton, Y. J.; Boersma, C.; Allamandola, L. J.; Horne, D.; Mayeur, P. A.

    2011-05-01

    DC314.8-5.1 is an isolated globule in the constellation of Circinus in the southern hemisphere. A 10.53 V-magnitude B9 star is illuminating a reflection nebula in the eastern part of this cloud. We surveyed this cloud using data from Spitzer IRS, IRAC and MIPS instruments. The main goals of our survey are to use mid-IR photometry along with 2MASS data to determine if this globule is a site of active star formation and to use IR spectroscopy to detect PAHs and investigate the energetics in the cloud. Here we describe preliminary results from the investigation of PAH emissions in DC314.8-5.1. Inspection of the IRAC 8 micron image shows widespread structured PAH emission towards this cloud. We have high resolution IRS spectra of HD130079 and low resolution IRS maps of the reflection nebula. In the spectral data we detect all the major PAH emissions in the 5 20 micron region. We find that the emission in the 12 14 micron region is quenched compared to the 11.3 micron feature suggesting most of the PAHs have solo hydrogen bonds. Spatial variation of PAH emissions seems to be identical as we move from the illuminating source, HD130079, towards the interior of the cloud except in the south-southwest region, where we see a slight enhancement. This enhancement is probably due to the skin effect (i.e., an excess due to viewing angle). We will analyze the ratios of various PAH features to i) put this globule in a global context with respect to the energetics of the region, and ii) determine the ionization state of the carrier molecules to investigate the interaction of PAHs with soft UV radiation. Combining results from the spectroscopic program with the stellar census data will provide new insight into the physical and evolutionary state of this isolated globule.

  18. Spitzer Observations of a 24 μm Shadow: Bok Globule CB 190

    NASA Astrophysics Data System (ADS)

    Stutz, Amelia M.; Bieging, John H.; Rieke, George H.; Shirley, Yancy L.; Balog, Zoltan; Gordon, Karl D.; Green, Elizabeth M.; Keene, Jocelyn; Kelly, Brandon C.; Rubin, Mark; Werner, Michael W.

    2007-08-01

    We present Spitzer observations of the dark globule CB 190 (LDN 771). We observe a roughly circular 24 μm shadow with a 70" radius. The extinction profile of this shadow matches the profile derived from 2MASS photometry at the outer edges of the globule and reaches a maximum of ~32 visual magnitudes at the center. The corresponding mass of CB 190 is ~10 Msolar. Our 12CO and 13CO J=2-1 data over a 10'×10' region centered on the shadow show a temperature ~10 K. The thermal continuum indicates a similar temperature for the dust. The molecular data also show evidence of freezeout onto dust grains. We estimate a distance to CB 190 of 400 pc using the spectroscopic parallax of a star associated with the globule. Bonnor-Ebert fits to the density profile, in conjunction with this distance, yield ξmax=7.2, indicating that CB 190 may be unstable. The high temperature (56 K) of the best-fit Bonnor-Ebert model is in contradiction with the CO and thermal continuum data, leading to the conclusion that the thermal pressure is not enough to prevent free-fall collapse. We also find that the turbulence in the cloud is inadequate to support it. However, the cloud may be supported by the magnetic field, if this field is at the average level for dark globules. Since the magnetic field will eventually leak out through ambipolar diffusion, it is likely that CB 190 is collapsing or in a late precollapse stage. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407.

  19. Coil-globule transition of poly(methyl methacrylate) in isoamyl acetate

    NASA Astrophysics Data System (ADS)

    Nakata, Mitsuo; Nakagawa, Tomohide

    1997-09-01

    The coil-globule transition was studied by static light scattering measurements on poly(methyl methacrylate) with the molecular weight Mw×10-6=2.35 and 4.4 in isoamyl acetate. Since the phase separation of the dilute solution occurred very slowly, the measurements could be made in the broad temperature range from near the Θ temperature 61 °C to 0 °C 30 min after a quench of the solution. The observed expansion factor α2 for the radius of gyration was represented as a function only of τM1/2 and showed a constant value at large -τM1/2 with τ being 1-Θ/T. A quantitative comparison between a recent theory for a contracted coil and the data of α2 revealed the coil-globule crossover phenomena. The behavior of plot of 1/α3 versus -τM1/2 was distinctly different in the three ranges, i.e., coil range, globule range, and range of a constant α. The plot of the observed second virial coefficient A2 against temperature yielded a minimum as predicted from a theory of A2 below the Θ temperature.

  20. Coil-globule transition of poly(methyl methacrylate) in isoamyl acetate

    SciTech Connect

    Nakata, M.; Nakagawa, T.

    1997-09-01

    The coil-globule transition was studied by static light scattering measurements on poly(methyl methacrylate) with the molecular weight M{sub w}{times}10{sup {minus}6}=2.35 and 4.4 in isoamyl acetate. Since the phase separation of the dilute solution occurred very slowly, the measurements could be made in the broad temperature range from near the {Theta} temperature 61{degree}C to 0{degree}C 30 min after a quench of the solution. The observed expansion factor {alpha}{sup 2} for the radius of gyration was represented as a function only of {tau}M{sup 1/2} and showed a constant value at large {minus}{tau}M{sup 1/2} with {tau} being 1{minus}{Theta}/T. A quantitative comparison between a recent theory for a contracted coil and the data of {alpha}{sup 2} revealed the coil-globule crossover phenomena. The behavior of plot of 1/{alpha}{sup 3} versus {minus}{tau}M{sup 1/2} was distinctly different in the three ranges, i.e., coil range, globule range, and range of a constant {alpha}. The plot of the observed second virial coefficient A{sub 2} against temperature yielded a minimum as predicted from a theory of A{sub 2} below the {Theta} temperature. {copyright} {ital 1997} {ital The American Physical Society}

  1. [Lipid Composition of Different Breeds of Milk Fat Globules by Confocal Raman Microscopy].

    PubMed

    Luo, Jie; Wang, Zi-wei; Song, Jun-hong; Pang, Rui-peng; Ren, Fa-zheng

    2016-01-01

    Different breeds of cows affect the form of fat exist in dairy products and the final functionality, which depended mainly on the composition of the milk fat globules(MFG). However, the relationship between the composition and breeds has not been illuminated. In our study, differences in the lipid content and fatty acid composition of native bovine, buffalo and yak MFG were investigated by confocal Raman spectroscopy. The research offers the possibility of acquisition and analysis of the Raman signal without disruption of the structure of fat globule. The results showed that yak MFG had a higher ratio of band intensities at 2 885/2 850 cm(-1), indicating yak MFG tend to have a triglyceride core in a fluid state with a milk fat globule membrane in a crystalline state. The buffalo and yak MFG had a higher level of unsaturation compared to bovine MFG, shown by a higher ratio of band intensities at 1 655/1 744 cm(-1). The results indicate that small MFG of buffalo is more unsaturated than yak, while the large MFG of buffalo is less unsaturated than the yak. Thus, selective use of cream with yak MFG would allow a harder and more costly churning process but lead to a softer butter. Buffalo milk which contains larger MFG is more suitable for cream and MFG membrane separation. PMID:27228754

  2. Spitzer and HHT Observations of Bok Globule B335: Isolated Star Formation Efficiency and Cloud Structure

    NASA Astrophysics Data System (ADS)

    Stutz, Amelia M.; Rubin, Mark; Werner, Michael W.; Rieke, George H.; Bieging, John H.; Keene, Jocelyn; Kang, Miju; Shirley, Yancy L.; Su, K. Y. L.; Velusamy, Thangasamy; Wilner, David J.

    2008-11-01

    We present infrared and millimeter observations of Barnard 335, the prototypical isolated Bok globule with an embedded protostar. Using Spitzer data we measure the source luminosity accurately; we also constrain the density profile of the innermost globule material near the protostar using the observation of an 8.0 μm shadow. Heinrich Hertz Telescope (HHT) observations of 12CO 2-1 confirm the detection of a flattened molecular core with diameter ~10,000 AU and the same orientation as the circumstellar disk (~100 to 200 AU in diameter). This structure is probably the same as that generating the 8.0 μm shadow and is expected from theoretical simulations of collapsing embedded protostars. We estimate the mass of the protostar to be only ~5% of the mass of the parent globule. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407.

  3. Pillars and globules at the edges of H ii regions. Confronting Herschel observations and numerical simulations

    NASA Astrophysics Data System (ADS)

    Tremblin, P.; Minier, V.; Schneider, N.; Audit, E.; Hill, T.; Didelon, P.; Peretto, N.; Arzoumanian, D.; Motte, F.; Zavagno, A.; Bontemps, S.; Anderson, L. D.; André, Ph.; Bernard, J. P.; Csengeri, T.; Di Francesco, J.; Elia, D.; Hennemann, M.; Könyves, V.; Marston, A. P.; Nguyen Luong, Q.; Rivera-Ingraham, A.; Roussel, H.; Sousbie, T.; Spinoglio, L.; White, G. J.; Williams, J.

    2013-12-01

    Context. Herschel far-infrared imaging observations have revealed the density structure of the interface between H ii regions and molecular clouds in great detail. In particular, pillars and globules are present in many high-mass star-forming regions, such as the Eagle nebula (M 16) and the Rosette molecular cloud, and understanding their origin will help characterize triggered star formation. Aims: The formation mechanisms of these structures are still being debated. The initial morphology of the molecular cloud and its turbulent state are key parameters since they generate deformations and curvatures of the shell during the expansion of the H ii region. Recent numerical simulations have shown how pillars can arise from the collapse of the shell in on itself and how globules can be formed from the interplay of the turbulent molecular cloud and the ionization from massive stars. The goal here is to test this scenario through recent observations of two massive star-forming regions, M 16 and the Rosette molecular cloud. Methods: First, the column density structure of the interface between molecular clouds and associated H ii regions was characterized using column density maps obtained from far-infrared imaging of the Herschel HOBYS key programme. Then, the DisPerSe algorithm was used on these maps to detect the compressed layers around the ionized gas and pillars in different evolutionary states. Column density profiles were constructed. Finally, their velocity structure was investigated using CO data, and all observational signatures were tested against some distinct diagnostics established from simulations. Results: The column density profiles have revealed the importance of compression at the edge of the ionized gas. The velocity properties of the structures, i.e. pillars and globules, are very close to what we predict from the numerical simulations. We have identified a good candidate of a nascent pillar in the Rosette molecular cloud that presents the velocity

  4. Imaging molten steel flow profiles

    NASA Astrophysics Data System (ADS)

    Binns, R.; Lyons, A. R. A.; Peyton, A. J.; Pritchard, W. D. N.

    2001-08-01

    Control of delivery of molten steel in continuous casting is critical in order to ensure stability of the meniscus and satisfactory mould flow patterns, which in turn are determinants of cleanness and surface quality of steel. Considerable effort has been expended over the last ten years on optimizing the design of the metal delivery system, particularly the pouring nozzle, in order to allow the consistent production of high quality steel at a high throughput. This paper looks forward to possible systems that are capable of tomographically imaging the distribution of molten steel flows in these applications. The paper will concentrate on the feasibility of using electromagnetic methods. The paper will present some initial results; an overview of the applied image reconstruction process will also be included. The paper will conclude with a discussion of possible future developments, such as the use of a tomographic or multi-frequency approach, future research on the reconstruction image procedures and the potential for visualization and flow measurement. There is a need for further research in this area and some priority areas for future work will be suggested.

  5. Molten carbonate fuel cell separator

    DOEpatents

    Nickols, R.C.

    1984-10-17

    In a stacked array of molten carbonate fuel cells, a fuel cell separator is positioned between adjacent fuel cells to provide isolation as well as a conductive path therebetween. The center portion of the fuel cell separator includes a generally rectangular, flat, electrical conductor. Around the periphery of the flat portion of the separator are positioned a plurality of elongated resilient flanges which form a gas-tight seal around the edges of the fuel cell. With one elongated flange resiliently engaging a respective edge of the center portion of the separator, the sealing flanges, which are preferably comprised of a noncorrosive material such as an alloy of yttrium, iron, aluminum or chromium, form a tight-fitting wet seal for confining the corrosive elements of the fuel cell therein. This arrangement permits a good conductive material which may be highly subject to corrosion and dissolution to be used in combination with a corrosion-resistant material in the fuel cell separator of a molten carbonate fuel cell for improved fuel cell conductivity and a gas-tight wet seal.

  6. Molten carbonate fuel cell separator

    DOEpatents

    Nickols, Richard C.

    1986-09-02

    In a stacked array of molten carbonate fuel cells, a fuel cell separator is positioned between adjacent fuel cells to provide isolation as well as a conductive path therebetween. The center portion of the fuel cell separator includes a generally rectangular, flat, electrical conductor. Around the periphery of the flat portion of the separator are positioned a plurality of elongated resilient flanges which form a gas-tight seal around the edges of the fuel cell. With one elongated flange resiliently engaging a respective edge of the center portion of the separator, the sealing flanges, which are preferably comprised of a noncorrosive material such as an alloy of yttrium, iron, aluminum or chromium, form a tight-fitting wet seal for confining the corrosive elements of the fuel cell therein. This arrangement permits a good conductive material which may be highly subject to corrosion and dissolution to be used in combination with a corrosion-resistant material in the fuel cell separator of a molten carbonate fuel cell for improved fuel cell conductivity and a gas-tight wet seal.

  7. Cathodic polarization of sulfur in molten salts

    SciTech Connect

    Demidov, A.I.; Dukhanin, G.P.; Morachevskii, A.G.; Simikov, I.A.

    1985-12-01

    As a continuation of studies on the electrochemical behavior of sulfur in molten salts, this paper reports work on the determination of lithium and potassium ion discharge potentials at a sulfur electrode during cathodic polarization in molten LiNO/sub 3/-LiNO/sub 2/-LiOH and LiNO/sub 3/-KNO/sub 3/ at 423/sup 0/K as well as in molten LiF-LiCl-LiI and LiC1-KC1 ay 650/sup 0/K. The studies were carried out by taking polarization curves in a pulsed galvanostatic mode using a three-electrode electrochemical cell. The sulfur electrode floating on the molten salt electrolyte contacted a 5-mm-diameter graphite rod that also touched the molten salt. The same patterns were observed for the cathodic polarization of sulfur in both halide and nitrate melts.

  8. Coil–globule transition in the denatured state of a small protein

    PubMed Central

    Sherman, Eilon; Haran, Gilad

    2006-01-01

    Upon transfer from strongly denaturing to native conditions, proteins undergo a collapse that either precedes folding or occurs simultaneously with it. This collapse is similar to the well known coil–globule transition of polymers. Here we employ single-molecule fluorescence methods to fully characterize the equilibrium coil–globule transition in the denatured state of the IgG-binding domain of protein L. By using FRET measurements on freely diffusing individual molecules, we determine the radius of gyration of the protein, which shows a gradual expansion as the concentration of the denaturant, guanidinium hydrochloride, is increased all the way up to 7 M. This expansion is observed also in fluorescence correlation spectroscopy measurements of the hydrodynamic radius of the protein. We analyze the radius of gyration measurements using the theory of the coil–globule transition of Sanchez [Sanchez, I. C. (1979) Macromolecules 12, 980–988], which balances the excluded volume entropy of the chain with the average interresidue interaction energy. In particular, we calculate the solvation energy of the denatured protein, a property that is not readily accessible in other experiments. The dependence of this energy on denaturant concentration is nonlinear, contrasting with the common linear extrapolation method used to describe denaturation energy. Interestingly, a fit to the binding model of chemical denaturation suggests a single denaturant binding site per protein residue. The size of the denatured protein under native conditions can be extrapolated from the data as well, showing that the fully collapsed state of protein is only ≈10% larger than the folded state. PMID:16857738

  9. Beryllium Interactions in Molten Salts

    SciTech Connect

    G. S. Smolik; M. F. Simpson; P. J. Pinhero; M. Hara; Y. Hatano; R. A. Anderl; J. P. Sharpe; T. Terai; S. Tanaka; D. A. Petti; D.-K. Sze

    2006-01-01

    Molten flibe (2LiF·BeF2) is a candidate as a cooling and tritium breeding media for future fusion power plants. Neutron interactions with the salt will produce tritium and release excess free fluorine ions. Beryllium metal has been demonstrated as an effective redox control agent to prevent free fluorine, or HF species, from reacting with structural metal components. The extent and rate of beryllium solubility in a pot design experiments to suppress continuously supplied hydrogen fluoride gas has been measured and modeled[ ]. This paper presents evidence of beryllium loss from specimens, a dependence of the loss upon bi-metal coupling, i.e., galvanic effect, and the partitioning of the beryllium to the salt and container materials. Various posttest investigative methods, viz., scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) were used to explore this behavior.

  10. X-ray microprobe measurements of the chemical compositions of ALH84001 carbonate globules

    SciTech Connect

    Flynn, G.J.; Sutton, S.R.; Keller, L.P.

    2004-01-28

    We measured minor element contents of carbonate from ALH84001 and report trends in tbe Ca, V, Mn and Sr in carbonate and the associated magnetite bands. McKay et al. suggested that carbonate globules in the ALH84001 meteorite from Mars contained evidence consistent with the development of bacterial life early in the history of Mars. This result provoked an extensive study of the ALH84001 meteorite. More recently Thomas-Keprta et al. have published a study showing that the magnetite associated with carbonate rims are of the size and shape produced by terrestrial bacteria. This paper has revived interest in ALH84001. The typical ALH84001 carbonate globule consists of four regions: a core of Fe-rich carbonate, a thin magnetite-rich band, a rim of Mn-rich carbonate, and another thin magnetite-rich band. Trace element analysis of each of these phases may allow us to address several important questions about these carbonates: (1) The origin of the magnetite-rich bands in the ALH84001 carbonate globules. If the magnetites are derived from the underlying carbonate through thermal decomposition (as proposed by Golden et al.), then we expect to see 'inherited' trace elements in these magnetite bands. (2) The origin of the rim carbonate, by determining whether the carbonate in the core has the same trace elements as the rim carbonates. (3) The age of the rim carbonate. Borg et al. dated the formation of the rim carbonate using the Rb/Sr chronometer. Borg et al. performed their measurements on an aliquot of what they called a high-Rb, low-Sr carbonate separate from the rim. We previously measured the trace element contents of chips from core and rim carbonates from an ALH84001 carbonate globule using an X-Ray Microprobe on Beamline X26A at the National Synchrotron Light Source. These measurements showed the rim carbonate had a very low Rb content, with Sr>>Rb, inconsistent with the {approx}5 ppm Rb reported by Borg et al. in the sample they dated by the Rb/Sr chronometer. The

  11. A Spitzer Survey of an Isolated Globule: DC314.8-5.1

    NASA Astrophysics Data System (ADS)

    Shenoy, S. S.; Whittet, D. C. B.; Pendleton, Y. J.; Boersma, C.; Allamandola, L. J.; Horne, D.; Mayeur, P. A.

    2011-05-01

    DC314.8-5.1 is an isolated globule in the constellation of Circinus in the Southern Hemisphere. A 10th magnitude B9 star is illuminating a reflection nebula in the eastern part of this cloud. Using this fortuitous association Whittet (2007) found the distance, mean number density of hydrogen and mass to be 342 /pm 50 pc, > 9 × 10^3 cm-3 and 30 ˜ 100 solar masses, respectively. We surveyed this cloud using data from Spitzer's IRS, IRAC and MIPS instruments. The main goals of our survey are to use mid-IR photometry along with 2MASS data to determine if this globule is a site of active star formation and to use IR spectroscopy to detect PAHs and investigate the energetics in the cloud. Results from the analysis of these data will lead to a better understanding of the interaction of dense molecular gas and dust in isolated cloud cores with a well defined soft UV radiation fields. In this poster we describe some preliminary results from the investigation of PAH emissions in DC314.8-5.1. Inspection of the IRAC 8 μm image shows widespread structured PAH emission toward this cloud. We have high resolution IRS spectra of HD130079 and low resolution IRS maps of the reflection nebula. In the spectral data we detect all the major PAH emissions in the 5 ˜ 20 μm region. We find that the emission in the 12 to 14 μm region is quenched compared to the 11.3 μm feature suggesting that most of the PAHs posses solo hydrogen bonds. Spatial variation of PAH emissions seems to be identical as we move from the illuminating source, HD130079, towards the interior of the cloud except in the south-southwest region, where we see a slight enhancement. This enhancement is probably due to the skin effect (i.e., in this direction we are viewing the edge of the cloud leading to an excess of PAH emission along the line of sight.) At present, we are analyzing the ratios of various PAH features to i) put this globule in a global context with respect to the energetics of the region, and ii

  12. Triggered star-formation in the bright rimmed globule IC1396A

    NASA Astrophysics Data System (ADS)

    Patel, Nimesh A.; Sicilia-Aguilar, Aurora; Goldsmith, Paul

    2015-01-01

    IC1396 is a well known HII region and molecular cloud complex surrounding the Trumpler 37 cluster of OB stars in the Cepheus OB2 association. The dense, elephant trunk shaped globules in this region typically show bright rims facing the central exciting O6 star HD~206267. This region, at a distance of 870 pc, is an excellent astrophysical laboratory for studying the feedback effects of massive stars on neighboring molecular clouds. Triggered star formation occurs when dense cores (which would otherwise remain stable) are compressed and made unstable by the sustained energy input from the OB association. Observationally it remains challenging to prove whether the onset of star-formation in such globules is triggered or spontaneous.Using the Submillimeter Array (SMA), we observed IC1396 globule A (Pottasch 1958 nomenclature), targeting four newly discovered protostars from recent Herschel PACS observations. Here we present 230 GHz molecular line (CO, 13CO, C18O, N2D+ and H2CO) and continuum results for the source IC1396A-PACS-1 (Sicilia-Aguilar et al. 2014). This is a Class 0 source very close to the edge of the ionization front and Herschel observations show this to be a most promisingcase of triggered star-formation. The SMA 230 GHz continuum source has a flux density of 280 mJy. We estimate a dust mass of about 0.1 Msun in this source which appears very compact in our 5" beam. CO, 13CO and C18O emission is largely resolved out by the interferometer and will require combined imaging with single-dish observations. (We have a parallel ongoing study being carried out with the IRAM 30m telescope). SMA N2D+ emission peaks on the continuum sourceand is partially resolved. H2CO emission appears to avoid the peak of continuum and N2D+, suggesting depletion. Both the morphology and kinematics in H2CO emission are indicative of internal disturbance, away from the PDR region into the globule.

  13. Morphology of globules and cenospheres in heavy fuel oil burner experiments

    SciTech Connect

    Kwack, E.Y.; Shakkottai, P.; Massier, P.F.; Back, L.H. )

    1992-04-01

    Number 6 fuel oil was heated, sprayed, and burned in an enclosure using a small commercial oil burner. Samples of residues that emerged from the flame were collected at various locations outside the flame and observed by a scanning electron microscope. Porous cenospheres, larger globules (of size 80 {mu}m to 200 {mu}m) that resemble soap bubbles formed from the very viscous liquid residue, and unburned oil drops were the types of particle collected. This paper reports on the qualitative relationships of the morphology of these particles to the temperature history to which they were subjected were made.

  14. Cathode for molten carbonate fuel cell

    DOEpatents

    Kaun, Thomas D.; Mrazek, Franklin C.

    1990-01-01

    A porous sintered cathode for a molten carbonate fuel cell and method of making same, the cathode including a skeletal structure of a first electronically conductive material slightly soluble in the electrolyte present in the molten carbonate fuel cell covered by fine particles of a second material of possibly lesser electronic conductivity insoluble in the electrolyte present in the molten carbonate fuel cell, the cathode having a porosity in the range of from about 60% to about 70% at steady-state cell operating conditions consisting of both macro-pores and micro-pores.

  15. Thermophysical properties data on molten semiconductors

    SciTech Connect

    Nakamura, S.; Hibiya, T. )

    1992-01-01

    Thermophysical properties of molten semiconductors are reviewed. Published data for viscosity, thermal conductivity, surface tension, and other properties are presented. Several measurement methods often used for molten semiconductors are described. Recommended values of thermophysical properties are tabulated for Si, Ge, GaAs, InP, InSb, GaSh, and other compounds. This review shows that further measurements of thermophysical properties of GaAs and InP in the molten state are required. It is also indicated that a very limited amount of data on emissivity is available. Space experiments relating to thermophysical property measurements are described briefly. 77 refs., 9 figs., 3 tabs.

  16. The dynamics of the biological membrane surrounding the buffalo milk fat globule investigated as a function of temperature.

    PubMed

    Nguyen, Hanh T H; Madec, Marie-Noëlle; Ong, Lydia; Kentish, Sandra E; Gras, Sally L; Lopez, Christelle

    2016-08-01

    The biological membrane surrounding fat globules in milk (the MFGM) is poorly understood, despite its importance in digestion and in determining the properties of fat globules. In this study, in situ structural investigations of buffalo MFGM were performed as a function of temperature (4-60°C), using confocal microscopy. We demonstrate that temperature and rate of temperature change affected the lipid domains formed in the MFGM with the lateral segregation (i) of high Tm lipids and cholesterol in a Lo phase for both TTm and (ii) of high Tm lipids in a gel phase for Tglobules during processing and digestion.

  17. Stability of milk fat globule membrane proteins toward human enzymatic gastrointestinal digestion.

    PubMed

    Le, T T; Van de Wiele, T; Do, T N H; Debyser, G; Struijs, K; Devreese, B; Dewettinck, K; Van Camp, J

    2012-05-01

    The milk fat globule membrane (MFGM) fraction refers to the thin film of polar lipids and membrane proteins that surrounds fat globules in milk. It is its unique biochemical composition that renders MFGM with some beneficial biological activities, such as anti-adhesive effects toward pathogens. However, a prerequisite for the putative bioactivity of MFGM is its stability during gastrointestinal digestion. We, therefore, subjected MFGM material, isolated from raw milk, to an in vitro enzymatic gastrointestinal digestion. Sodium dodecyl sulfate PAGE, in combination with 2 staining methods, Coomassie Blue and periodic acid Schiff staining, was used to evaluate polypeptide patterns of the digest, whereas mass spectrometry was used to confirm the presence of specific MFGM proteins. Generally, it was observed that glycoproteins showed higher resistance to endogenous proteases compared with non-glycosylated proteins. Mucin 1 displayed the highest resistance to digestion and a considerable part of this protein was still detected at its original molecular weight after gastric and small intestine digestion. Cluster of differentiation 36 was also quite resistant to pepsin. A significant part of periodic acid Schiff 6/7 survived the gastric digestion, provided that the lipid moiety was not removed from the MFGM material. Overall, MFGM glycoproteins are generally more resistant to gastrointestinal digestion than serum milk proteins and the presence of lipids, besides glycosylation, may protect MFGM glycoproteins from gastrointestinal digestion. This gastrointestinal stability makes MFGM glycoproteins amenable to further studies in which their putative health-promoting effects can be explored.

  18. N-15-Rich Organic Globules in a Cluster IDP and the Bells CM2 Chondrite

    NASA Technical Reports Server (NTRS)

    Messenger, S.; Nakamura-Messenger, K.; Keller, Lindsay P.

    2008-01-01

    Organic matter in primitive meteorites and chondritic porous interplanetary dust particles (CP IDPs) is commonly enriched in D/H and 15N/14N relative to terrestrial values [1-3]. These anomalies are ascribed to the partial preservation of presolar cold molecular cloud material [1]. Some meteorites and IDPs contain m-size inclusions with extreme H and N isotopic anomalies [2-4], possibly due to preserved pristine primordial organic grains. We recently showed that the in the Tagish Lake meteorite, the principle carriers of these anomalies are sub- m, hollow organic globules [5]. The globules likely formed by photochemical processing of organic ices in a cold molecular cloud or the outermost regions of the protosolar disk [5]. We proposed that similar materials should be common among primitive meteorites, IDPs, and comets. Similar objects have been observed in organic extracts of carbonaceous chondrites [6-8], however their N and H isotopic compositions are generally unknown. Bulk H and N isotopic compositions may indicate which meteorites best preserve interstellar organic compounds. Thus, we selected the Bells CM2 carbonaceous chondrites for study based on its large bulk 15N (+335 %) and D (+990 %) [9].

  19. Molten salt destruction of energetic waste materials

    DOEpatents

    Brummond, W.A.; Upadhye, R.S.; Pruneda, C.O.

    1995-07-18

    A molten salt destruction process is used to treat and destroy energetic waste materials such as high explosives, propellants, and rocket fuels. The energetic material is pre-blended with a solid or fluid diluent in safe proportions to form a fluid fuel mixture. The fuel mixture is rapidly introduced into a high temperature molten salt bath. A stream of molten salt is removed from the vessel and may be recycled as diluent. Additionally, the molten salt stream may be pumped from the reactor, circulated outside the reactor for further processing, and delivered back into the reactor or cooled and circulated to the feed delivery system to further dilute the fuel mixture entering the reactor. 4 figs.

  20. Molten salt destruction of energetic waste materials

    DOEpatents

    Brummond, William A.; Upadhye, Ravindra S.; Pruneda, Cesar O.

    1995-01-01

    A molten salt destruction process is used to treat and destroy energetic waste materials such as high explosives, propellants, and rocket fuels. The energetic material is pre-blended with a solid or fluid diluent in safe proportions to form a fluid fuel mixture. The fuel mixture is rapidly introduced into a high temperature molten salt bath. A stream of molten salt is removed from the vessel and may be recycled as diluent. Additionally, the molten salt stream may be pumped from the reactor, circulated outside the reactor for further processing, and delivered back into the reactor or cooled and circulated to the feed delivery system to further dilute the fuel mixture entering the reactor.

  1. The behavior of water in molten salts

    SciTech Connect

    White, S.H.; Twardoch, U.M.

    1983-05-01

    The differing behavior of water equilibrated with three separate molten salt solvents is discussed with respect to the chemistry of the solutions and the electroreductive mechanisms at gold electrodes.

  2. Molten Hydroxide Trapping Process for Radioiodine

    SciTech Connect

    Trowbridge, L.D.

    2003-01-28

    A molten hydroxide trapping process has been considered for removing radioiodine species from off-gas streams whereby iodine is reacted directly with molten hydroxides such as NaOH or KOH. The resulting product is the corresponding iodide, which can be separated by simple cooling of the molten mixture to grow the iodide primary phase once the mixture reaches 70-80 mol% in the iodide component. Thermodynamic analysis indicates that such a chemical process is highly favorable. Experimental testing of the trapping process using molecular iodine showed trapping of up to 96% of the volatile iodine. The trapping efficiency was dependent on operational parameters such as temperature and gas-melt contact efficiency, and higher efficiencies are expected as the process is further developed. While an iodide phase could be effectively isolated by slow cooling of a molten iodide-hydroxide mixture, the persistent appearance of hydroxide indicated that an appreciable solubility of hydroxide occurred in the iodide phase.

  3. Corrosion of Mullite by Molten Salts

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Lee, Kang N.; Yoshio, Tetsuo

    1996-01-01

    The interaction of molten salts of different Na2O activities and mullite is examined with furnace and burner tests. The more-acidic molten salts form small amounts of Al2O3; the more-basic molten salts form various Na2O-Al2O3-SiO2 compounds. The results are interpreted using the Na2O-Al203-SiO2 ternary phase diagram, and some possible diffusion paths are discussed. The generally higher melting points of Na2O-Al2O3-SiO2 compounds lead to better behavior of mullite in molten salts, as compared to SiO2-protected ceramics such as SiC. Mullite-coated SiC is discussed, and the corrosion behavior is evaluated.

  4. Electrode for molten carbonate fuel cell

    DOEpatents

    Iacovangelo, Charles D.; Zarnoch, Kenneth P.

    1983-01-01

    A sintered porous electrode useful for a molten carbonate fuel cell is produced which is composed of a plurality of 5 wt. % to 95 wt. % nickel balance copper alloy encapsulated ceramic particles sintered together by the alloy.

  5. Recirculating Molten Metal Supply System And Method

    DOEpatents

    Kinosz, Michael J.; Meyer, Thomas N.

    2003-07-01

    The melter furnace includes a heating chamber (16), a pump chamber (18), a degassing chamber (20), and a filter chamber (22). The pump chamber (18) is located adjacent the heating chamber (16) and houses a molten metal pump (30). The degassing chamber (20) is located adjacent and in fluid communication with the pump chamber (18), and houses a degassing mechanism (36). The filter chamber (22) is located adjacent and in fluid communication with the degassing chamber (20). The filter chamber (22) includes a molten metal filter (38). The melter furnace (12) is used to supply molten metal to an externally located holder furnace (14), which then recirculates molten metal back to the melter furnace (12).

  6. Data from proteomic characterization and comparison of mammalian milk fat globule proteomes by iTRAQ analysis.

    PubMed

    Yang, Yongxin; Zheng, Nan; Zhao, Xiaowei; Zhang, Yangdong; Han, Rongwei; Ma, Lu; Zhao, Shengguo; Li, Songli; Guo, Tongjun; Wang, Jiaqi

    2015-06-01

    Milk fat globules memebrane (MFGM)-enriched proteomes from Holstein, Jersey, yak, buffalo, goat, camel, horse, and human were extracted and identified by an iTRAQ quantification proteomic approach. Proteomes data were analyzed by bioinformatic and multivariate statistical analysis and used to present the characteristic traits of the MFGM proteins among the studied mammals. The data of this study are also related to the research article "Proteomic characterization and comparison of mammalian milk fat globule proteomes by iTRAQ analysis" in the Journal of Proteomics [1]. PMID:26217709

  7. Structure of molten titanium dioxide

    NASA Astrophysics Data System (ADS)

    Alderman, O. L. G.; Skinner, L. B.; Benmore, C. J.; Tamalonis, A.; Weber, J. K. R.

    2014-09-01

    The x-ray structure factor of molten TiO2 has been measured, enabled by the use of aerodynamic levitation and laser beam heating, to a temperature of T=2250(30)K. The Ti-O coordination number in the melt is close to nTiO=5.0(2), with modal Ti-O bond length rTiO=1.881(5)Å, both values being significantly smaller than for the high temperature stable rutile crystal structure (nTiO=6.0,rTiO=1.959Å). The structural differences between melt and crystal are qualitatively similar to those for alumina, which is rationalized in terms of the similar field strengths of Ti4+ and Al3+. The diffraction data are used to generate physically and chemically reasonable structural models, which are then compared to the predictions based on various classical molecular dynamics (MD) potentials. Interatomic potentials, suitable for modeling molten TiO2, are introduced, given the inability of existing MD models to reproduce the diffraction data. These potentials have the additional advantage of being able to predict the density and thermal expansion of the melt, as well as solid amorphous TiO2, in agreement with published results. This is of critical importance given the strong correlation between density and structural parameters such as nTiO. The large thermal expansion of the melt is associated with weakly temperature dependent structural changes, whereby simulations show that nTiO=5.85(2)-[3.0(1)×10-4]T(K ,2.75Åcutoff). The TiO2 liquid is structurally analogous to the geophysically relevant high pressure liquid silica system at around 27 GPa. We argue that the predominance of fivefold polyhedra in the melt implies the existence of as-yet-undiscovered TiO2 polymorphs, based on lower-than-octahedral coordination numbers, which are likely to be metastable under ambient conditions. Given the industrial importance of titanium oxides, experimental and computational searches for such polymorphs are well warranted.

  8. Structure of molten titanium dioxide

    SciTech Connect

    Alderman, O. L. G.; Skinner, L. B.; Benmore, C. J.; Tamalonis, A.; Weber, J. K. R.

    2014-09-18

    The x-ray structure factor of molten TiO2 has been measured for the first time, enabled by the use of aerodynamic levitation and laser beam heating, to a temperature of T = 2250(30) K. Ti-O coordination number in the melt is close to nTiO = 5.0(2), with modal Ti-O bond length rTiO = 1.881(5) Å, both values being significantly smaller than for the high temperature stable Rutile crystal structure (nTiO = 6.0, rTiO = 1.959 Å). The structural differences between melt and crystal are qualitatively similar to those for alumina, which is rationalized in terms of the similar field strengths of Ti4+ and Al3+. The diffraction data are used to generate physically and chemically reasonable structural models, which are then compared to the predictions based on various classical molecular dynamics (MD) potentials. New interatomic potentials, suitable for modelling molten TiO2, are introduced, given the inability of existing MD models to reproduce the diffraction data. These new potentials have the additional great advantage of being able to predict the density and thermal expansion of the melt, as well as solid amorphous TiO2, in agreement with published results. This is of critical importance given the strong correlation between density and structural parameters such as nTiO. The large thermal expansion of the melt is associated with weakly temperature dependent structural changes, whereby simulations show that nTiO = 5.85(2) – (3.0(1) x 10-4 )T (K, 2.75 Å cut-off). The TiO2 liquid is structurally analogous to the geophysically relevant high pressure liquid silica system at around 27 GPa. We argue that the predominance of 5-fold polyhedra in the melt implies the existence of as yet undiscovered TiO2 polymorphs, based on lowerthan-octahedral coordination numbers, which are likely to be metastable under ambient conditions. Given the industrial importance of titanium oxides, experimental and computational searches for such polymorphs are well warranted.

  9. Extracting information from the molten salt database

    NASA Astrophysics Data System (ADS)

    Gadzuric, Slobodan; Suh, Changwon; Gaune-Escard, Marcelle; Rajan, Krishna

    2006-12-01

    Molten salt technology is a catchall phrase that includes some very diverse technologies; electrochemistry, heat transfer, chemical oxidation/reduction baths, and nuclear reactors. All of these technologies are linked by the general characteristics of molten salts that can function as solvents, have good heat-transfer characteristics, function like a fluid, can attain very high temperatures, can conduct electricity, and also may have chemical catalytic properties. The Janz molten salt database is the most comprehensive compilation of property data about molten salts available today and is widely used for both fundamental and applied purposes. Databases are traditionally viewed as “static” documents that are used in a “search and retrieval” mode. These static data can be transformed by informatics and data mining tools into a dynamic dataset for analysis of the properties of the, materials and for making predictions. While this approch has been successful in the chemical and biochemical sciences in searching for and establishing structure-property relationships, it is not widely used in the materials science community. Because the design of the original molten salt database was not oriented toward this informatics goal, it was essential to evaluate this dataset in terms of data mining standards. Two techniques were used—a projection (principal components analysis (PCA)) and a predictive method (partial least squares (PLS))—in conjunction with fundamental knowledge acquired from the long-term practice of molten salt chemistry.

  10. Vacuum Refining of Molten Silicon

    NASA Astrophysics Data System (ADS)

    Safarian, Jafar; Tangstad, Merete

    2012-12-01

    Metallurgical fundamentals for vacuum refining of molten silicon and the behavior of different impurities in this process are studied. A novel mass transfer model for the removal of volatile impurities from silicon in vacuum induction refining is developed. The boundary conditions for vacuum refining system—the equilibrium partial pressures of the dissolved elements and their actual partial pressures under vacuum—are determined through thermodynamic and kinetic approaches. It is indicated that the vacuum removal kinetics of the impurities is different, and it is controlled by one, two, or all the three subsequent reaction mechanisms—mass transfer in a melt boundary layer, chemical evaporation on the melt surface, and mass transfer in the gas phase. Vacuum refining experimental results of this study and literature data are used to study the model validation. The model provides reliable results and shows correlation with the experimental data for many volatile elements. Kinetics of phosphorus removal, which is an important impurity in the production of solar grade silicon, is properly predicted by the model, and it is observed that phosphorus elimination from silicon is significantly increased with increasing process temperature.

  11. Fluoroalcohols induced unfolding of Succinylated Con A: native like beta-structure in partially folded intermediate and alpha-helix in molten globule like state.

    PubMed

    Fatima, Sadaf; Ahmad, Basir; Khan, Rizwan Hasan

    2006-10-15

    Concanavalin A (Con A) exists in dimeric state at pH 5. In concentration range 20-60% (v/v) 2,2,2-trifluoroethanol (TFE) and 2-40% (v/v) 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), Con A at pH 5.0 shows visible aggregation. However, when succinyl Con A was used, no aggregation was observed in the entire concentration range of fluoroalcohols (0-90% v/v TFE and HFIP) and resulted in stable alpha-helix formation. Temperature-induced concentration-dependent aggregation in Con A was also found to be prevented/reduced in succinylated form. Possible role of electrostatic repulsion among residues in the prevention of hydrophobically driven aggregation has been discussed. Results indicate that succinylation of a protein resulted in greater stability (in both beta-sheet and alpha-helical forms) against alcohol-induced and temperature-induced concentration-dependent aggregation and this observation may play significant role in amyloid-forming proteins. Effect of TFE and HFIP on the conformation of a dimeric protein, Succinylated Con A, has been investigated by circular dichroism (CD), fluorescence emission spectroscopy, binding of hydrophobic dye ANS (8-anilinonaphthalene-1-sulfonic acid). Far UV-CD, a probe for secondary structure shows loss of native secondary structure in the presence of low concentration of both the alcohols, TFE (10% v/v) and HFIP (4% v/v). Upon addition of higher concentration of these alcohols, Succinylated Con A exhibited transformation from beta-sheet to alpha-helical structure. Intrinsic tryptophan fluorescence studies, ANS binding and near UV-CD experiments indicate the protein is more expanded, have more exposed hydrophobic surfaces and highly disrupted tertiary structure at 60% (v/v) TFE and 30% (v/v) HFIP concentrations. Taken together, these results it might be concluded that TFE and HFIP induce two intermediate states at their low and high concentrations in Succinyl Con A.

  12. Thermal Decomposition of Siderite-Pyrite Assemblages: Implications for Sulfide Mineralogy in Martian Meteorite ALH84001 Carbonate Globules

    NASA Astrophysics Data System (ADS)

    Golden, D. C.; Ming, D. W.; Lauer, H. V., Jr.; Morris, R. V.

    2004-03-01

    Closed system heating experiments of siderite-pyrite mixtures produce magnetite-pyrrhotite associations similar to those reported for black rims of the carbonate globules in ALH84001 Martian meteorite. These results support an inorganic formation process for magnetite and pyrrhotite in ALH84001.

  13. Method and apparatus for atomization and spraying of molten metals

    DOEpatents

    Hobson, D.O.; Alexeff, I.; Sikka, V.K.

    1988-07-19

    A method and device for dispersing molten metal into fine particulate spray, the method comprises applying an electric current through the molten metal and simultaneously applying a magnetic field to the molten metal in a plane perpendicular to the electric current, whereby the molten metal is caused to form into droplets at an angle perpendicular to both the electric current and the magnetic field. The device comprises a structure for providing a molten metal, appropriately arranged electrodes for applying an electric current through the molten metal, and a magnet for providing a magnetic field in a plane perpendicular to the electric current. 11 figs.

  14. Method and apparatus for atomization and spraying of molten metals

    DOEpatents

    Hobson, David O.; Alexeff, Igor; Sikka, Vinod K.

    1990-01-01

    A method and device for dispersing molten metal into fine particulate spray, the method comprises applying an electric current through the molten metal and simultaneously applying a magnetic field to the molten metal in a plane perpendicular to the electric current, whereby the molten metal is caused to form into droplets at an angle perpendicular to both the electric current and the magnetic field. The device comprises a structure for providing a molten metal, appropriately arranged electrodes for applying an electric current through the molten metal, and a magnet for providing a magnetic field in a plane perpendicular to the electric current.

  15. Molten salt chemistry: An introduction and selected applications

    SciTech Connect

    Mamantov, G.; Marassi, R.

    1987-01-01

    The major fundamental topics covered are the structure of melts, thermodynamics of molten salt mixtures, theoretical and experimental studies of transport processes, metal-metal salt solutions, solvent properties of melt systems, acid-base effects in molten salt chemistry, electronic absorption, vibrational and nuclear magnetic resonance spectroscopy of melt systems, electrochemistry and electroanalytical chemistry in molten salts, and organic chemistry in molten salts. The applied aspects include the chemistry of aluminium production, electrodeposition using molten salts, and molten salt batteries and fuel cells.

  16. A method of measuring a molten metal liquid pool volume

    DOEpatents

    Garcia, G.V.; Carlson, N.M., Donaldson, A.D.

    1990-12-12

    A method of measuring a molten metal liquid pool volume and in particular molten titanium liquid pools, including the steps of (a) generating an ultrasonic wave at the surface of the molten metal liquid pool, (b) shining a light on the surface of a molten metal liquid pool, (c) detecting a change in the frequency of light, (d) detecting an ultrasonic wave echo at the surface of the molten metal liquid pool, and (e) computing the volume of the molten metal liquid. 3 figs.

  17. Molten fatty acid based microemulsions.

    PubMed

    Noirjean, Cecile; Testard, Fabienne; Dejugnat, Christophe; Jestin, Jacques; Carriere, David

    2016-06-21

    We show that ternary mixtures of water (polar phase), myristic acid (MA, apolar phase) and cetyltrimethylammonium bromide (CTAB, cationic surfactant) studied above the melting point of myristic acid allow the preparation of microemulsions without adding a salt or a co-surfactant. The combination of SANS, SAXS/WAXS, DSC, and phase diagram determination allows a complete characterization of the structures and interactions between components in the molten fatty acid based microemulsions. For the different structures characterized (microemulsion, lamellar or hexagonal phases), a similar thermal behaviour is observed for all ternary MA/CTAB/water monophasic samples and for binary MA/CTAB mixtures without water: crystalline myristic acid melts at 52 °C, and a thermal transition at 70 °C is assigned to the breaking of hydrogen bounds inside the mixed myristic acid/CTAB complex (being the surfactant film in the ternary system). Water determines the film curvature, hence the structures observed at high temperature, but does not influence the thermal behaviour of the ternary system. Myristic acid is partitioned in two "species" that behave independently: pure myristic acid and myristic acid associated with CTAB to form an equimolar complex that plays the role of the surfactant film. We therefore show that myristic acid plays the role of a solvent (oil) and a co-surfactant allowing the fine tuning of the structure of oil and water mixtures. This solvosurfactant behaviour of long chain fatty acid opens the way for new formulations with a complex structure without the addition of any extra compound. PMID:27241163

  18. Comparative proteomics of milk fat globule membrane in goat colostrum and mature milk.

    PubMed

    Lu, Jing; Liu, Lu; Pang, Xiaoyang; Zhang, Shuwen; Jia, Zhenhu; Ma, Changlu; Zhao, Lili; Lv, Jiaping

    2016-10-15

    As an important nutrient source in large area of world, the composition and nutritional value of goat milk are not well deliberated. Detailed annotation of protein composition is essential to address the physiological and nutritional value of goat milk. In the present study, 423 colostrum and mature goat milk fat globule membrane (MFGM) proteins were identified. The abundance of 189 proteins was significantly different between colostrums and mature milk MFGM. The acute phase proteins were higher in colostrums MFGM than those in mature milk MFGM which protected newborns at the beginning of life. Proteins related to synthesis and secretion were conserved through lactation to ensure the milk production. Of note, long term depression (LTD) proteins were observed in colostrum and mature milk MFGM. Milk LTD proteins could be potential biomarkers for diagnosis of lactation related depressive syndromes and should be taken into considerations of their effects on newborns. PMID:27173528

  19. Jeans analysis of Bok globules in {\\varvec{f(R)}} gravity

    NASA Astrophysics Data System (ADS)

    Vainio, Jaakko; Vilja, Iiro

    2016-10-01

    We examine the effects of f( R) gravity on Jeans analysis of collapsing dust clouds. We provide a method for testing modified gravity models by their effects on star formation as the presence of f(R) gravity is found to modify the limit for collapse. In this analysis we add perturbations to a de Sitter background. As the standard Einstein-Hilbert Lagrangian is modified, new types of dynamics emerge. Depending on the characteristics of a chosen f( R) model, the appearance of new limits is possible. The physicality of these limits is further examined. We find the asymptotic Jeans masses for f( R) theories compared to standard Jeans mass. Through this ratio, the effects of the f( R) modified Jeans mass for viable theories are examined in molecular clouds. Bok globules have a mass range comparable to Jeans masses in question and are therefore used for comparing different f( R) models. Viable theories are found to assist in star formation.

  20. Role of milk fat globule-epidermal growth factor 8 in osteoimmunology.

    PubMed

    Sinningen, Kathrin; Thiele, Sylvia; Hofbauer, Lorenz C; Rauner, Martina

    2016-01-01

    Milk fat globule-epidermal growth factor 8 (MFG-E8) is a glycoprotein that is abundantly expressed in various tissues and has a pivotal role in the phagocytic clearance of apoptotic cells. However, MFG-E8 has also gained significant attention because of its wide range of functions in autoimmunity, inflammation and tissue homeostasis. More recently, MFG-E8 has been identified as a critical regulator of bone homeostasis, being expressed in both, osteoblasts and osteoclasts. In addition, it was shown that MFG-E8 fulfils an active role in modulating inflammatory processes, suggesting an anti-inflammatory role of MFG-E8 and proposing it as a novel therapeutic target for inflammatory diseases. This concise review focusses on the expression and regulation of MFG-E8 in the context of inflammatory bone diseases, highlights its role in the pathophysiology of osteoimmune diseases and discusses the therapeutic potential of MFG-E8. PMID:27579162

  1. Composition and microstructure of colostrum and mature bovine milk fat globule membrane.

    PubMed

    Zou, Xiaoqiang; Guo, Zheng; Jin, Qingzhe; Huang, Jianhua; Cheong, Lingzhi; Xu, Xuebing; Wang, Xingguo

    2015-10-15

    The microstructures of colostrum and mature bovine milk fat globule membrane (MFGM) were investigated using confocal laser scanning microscopy (CLSM) at different temperatures, and the relationships between microstructure variations and the chemical compositions of the MFGM were also examined. Using a fluorophore-labeled phospholipid probe, we found that non-fluorescent domains on the MFGM were positively correlated with the amount of sphingomyelin at both room (20 °C) and physiological (37 °C) temperatures. However, at the storage temperature (4 °C), there were more non-fluorescent domains on the MFGM. These results indicate that the heterogeneities in the MFGM are most likely to be the result of the lateral segregation of sphingomyelin at the room and physiological temperatures, and at the storage temperature, phospholipids with saturated fatty acids affect the formation of these domains. PMID:25952880

  2. Short communication: Milk fat globule membrane as a potential delivery system for liposoluble nutrients.

    PubMed

    Bezelgues, J-B; Morgan, F; Palomo, G; Crosset-Perrotin, L; Ducret, P

    2009-06-01

    A soft physical process was used to extract and purified bovine milk fat globule membrane (MFGM) fractions on a pilot scale. Oil-in-water emulsions enriched with alpha-tocopherol and lycopene were then prepared and stabilized with the extracted MFGM fraction and conventional milk protein concentrates (i.e., whey proteins, caseinate). A protocol of in vitro digestion was set up to evaluate the bioaccessibility of the tocopherol and lycopene in the different emulsions. Bioaccessibility was defined as the capacity of liposoluble compounds to be transferred into mixed micelles formed during the digestion process. Results showed that the accumulation of the tocopherol and lycopene into mixed micelles in MFGM-stabilized emulsions was around 2-fold greater than in emulsions stabilized with conventional milk proteins. This result confirms the potential use of MFGM-enriched ingredients as delivery systems of liposoluble nutrients in food formulations. PMID:19447983

  3. Kinetics of coil-globule transition of poly(methyl methacrylate) in isoamyl acetate

    NASA Astrophysics Data System (ADS)

    Nakata, Mitsuo; Nakagawa, Tomohide

    1999-02-01

    The kinetics of coil-globule transition was studied by static light scattering measurements on poly(methyl methacrylate) with the molecular weight Mw×10-6=8.4 and 12.2 in isoamyl acetate. Since the phase separation of the solution occurred very slowly, the mean-square radius of gyration of the polymer could be determined for a long time after quench to far below the θ-temperature 61 °C. The expansion factor α2 observed 30 min after quench to below the coil-globule crossover point, deviated largely from theoretical predictions, and was found to be a transient one. Chain collapse processes were measured in the time range from 30 min to a few thousand min after the quenches to 30 °C and 45 °C for Mw=12.2×106 and to 30 °C for Mw=8.4×106. The expansion factor in each process approached a constant value αeq2 in the time range. The collapse process was expressed as a function of time t(min) by α2=α∞2+{b/(t+c)}p, where b, c, p, and α∞2 were constant, independent of time. In all the three processes the constants had values near p˜0.5, b˜0.4, c˜0.6, and α∞2 was slightly smaller than αeq2. The constant c was introduced to satisfy the initial condition of α2=1 at t=0. This behavior of α2(t) and a comparison with kinetic theories of chain collapse concluded that the chain collapse occurred in a single stage process without formation of chain knots.

  4. The protein and lipid composition of the membrane of milk fat globules depends on their size.

    PubMed

    Lu, Jing; Argov-Argaman, Nurit; Anggrek, Jeni; Boeren, Sjef; van Hooijdonk, Toon; Vervoort, Jacques; Hettinga, Kasper Arthur

    2016-06-01

    In bovine milk, fat globules (MFG) have a heterogeneous size distribution with diameters ranging from 0.1 to 15 µm. Although efforts have been made to explain differences in lipid composition, little is known about the protein composition of MFG membranes (MFGM) in different sizes of MFG. In this study, protein and lipid analyses were combined to study MFG formation and secretion. Two different sized MFG fractions (7.6±0.9 µm and 3.3±1.2 µm) were obtained by centrifugation. The protein composition of MFGM in the large and small MFG fractions was compared using mass-spectrometry-based proteomics techniques. The lipid composition and fatty acid composition of MFG was determined using HPLC-evaporative light-scattering detector and gas chromatography, respectively. Two frequently studied proteins in lipid droplet biogenesis, perilipin-2 and TIP47, were increased in the large and small MFG fractions, respectively. In the large MFG fraction, besides perilipin-2, cytoplasmic vesicle proteins (heat shock proteins, 14-3-3 proteins, and Rabs), microfilaments and intermediate filament-related proteins (actin and vimentin), host defense proteins (cathelicidins), and phosphatidylinositol were higher in concentration. On the other hand, cholesterol synthesis enzymes [lanosterol synthase and sterol-4-α-carboxylate 3-dehydrogenase (decarboxylating)], cholesterol, unsaturated fatty acids, and phosphatidylethanolamine were, besides TIP47, higher in concentration in the small MFG fraction. These results suggest that vesicle proteins, microfilaments and intermediate filaments, cholesterol, and specific phospholipids play an important role in lipid droplet growth, secretion, or both. The observations from this study clearly demonstrated the difference in protein and lipid composition between small and large MFG fractions. Studying the role of these components in more detail in future experiments may lead to a better understanding of fat globule formation and secretion.

  5. Molten salts and energy related materials.

    PubMed

    Fray, Derek

    2016-08-15

    Molten salts have been known for centuries and have been used for the extraction of aluminium for over one hundred years and as high temperature fluxes in metal processing. This and other molten salt routes have gradually become more energy efficient and less polluting, but there have been few major breakthroughs. This paper will explore some recent innovations that could lead to substantial reductions in the energy consumed in metal production and in carbon dioxide production. Another way that molten salts can contribute to an energy efficient world is by creating better high temperature fuel cells and novel high temperature batteries, or by acting as the medium that can create novel materials that can find applications in high energy batteries and other energy saving devices, such as capacitors. Carbonate melts can be used to absorb carbon dioxide, which can be converted into C, CO and carbon nanoparticles. Molten salts can also be used to create black silicon that can absorb more sunlight over a wider range of wavelengths. Overall, there are many opportunities to explore for molten salts to play in an efficient, low carbon world. PMID:27276650

  6. Molten salts and nuclear energy production

    NASA Astrophysics Data System (ADS)

    Le Brun, Christian

    2007-01-01

    Molten salts (fluorides or chlorides) were considered near the beginning of research into nuclear energy production. This was initially due to their advantageous physical and chemical properties: good heat transfer capacity, radiation insensitivity, high boiling point, wide range solubility for actinides. In addition it was realised that molten salts could be used in numerous situations: high temperature heat transfer, core coolants with solid fuels, liquid fuel in a molten salt reactor, solvents for spent nuclear solid fuel in the case of pyro-reprocessing and coolant and tritium production in the case of fusion. Molten salt reactors, one of the six innovative concepts chosen by the Generation IV international forum, are particularly interesting for use as either waste incinerators or thorium cycle systems. As the neutron balance in the thorium cycle is very tight, the possibility to perform online extraction of some fission product poisons from the salt is very attractive. In this article the most important questions that must be addressed to demonstrate the feasibility of molten salt reactor will be reviewed.

  7. Molten salts and energy related materials.

    PubMed

    Fray, Derek

    2016-08-15

    Molten salts have been known for centuries and have been used for the extraction of aluminium for over one hundred years and as high temperature fluxes in metal processing. This and other molten salt routes have gradually become more energy efficient and less polluting, but there have been few major breakthroughs. This paper will explore some recent innovations that could lead to substantial reductions in the energy consumed in metal production and in carbon dioxide production. Another way that molten salts can contribute to an energy efficient world is by creating better high temperature fuel cells and novel high temperature batteries, or by acting as the medium that can create novel materials that can find applications in high energy batteries and other energy saving devices, such as capacitors. Carbonate melts can be used to absorb carbon dioxide, which can be converted into C, CO and carbon nanoparticles. Molten salts can also be used to create black silicon that can absorb more sunlight over a wider range of wavelengths. Overall, there are many opportunities to explore for molten salts to play in an efficient, low carbon world.

  8. Dynamics of the Molten Contact Line

    NASA Technical Reports Server (NTRS)

    Sonin, Ain A.; Schiaffino, Stefano

    1996-01-01

    In contrast to the ordinary contact line problem, virtually no information is available on the similar problem associated with a molten material spreading on a solid which is below the melt's fusion point. The latter is a more complex problem which heat transfer and solidification take place simultaneously with spreading, and requires answers not only for the hot melt's advance speed over the cold solid as a function of contact angle, but also for how one is to predict the point of the molten contact line's arrest by freezing. This issues are of importance in evolving methods of materials processing. The purpose of our work is to develop, based on both experiments and theory, an understanding of the dynamic processes that occur when a molten droplet touches a subcooled solid, spreads partly over it by capillary action, and freezes. We seek answers to the following basic questions. First, what is the relationship between the melt's contact line speed and the apparent (dynamic) contact angle? Secondly, at what point will the contact line modon be arrested by freezing? The talk will describe three components of our work: (1) deposition experiments with small molten droplets; (2) investigation of the dynamics of the molten contact line by means of a novel forced spreading method; and (3) an attempt to provide a theoretical framework for answering the basic questions posed above.

  9. Physical properties of molten carbonate electrolyte

    SciTech Connect

    Kojima, T.; Yanagida, M.; Tanimoto, K.

    1996-12-31

    Recently many kinds of compositions of molten carbonate electrolyte have been applied to molten carbonate fuel cell in order to avoid the several problems such as corrosion of separator plate and NiO cathode dissolution. Many researchers recognize that the addition of alkaline earth (Ca, Sr, and Ba) carbonate to Li{sub 2}CO{sub 3}-Na{sub 2}CO{sub 3} and Li{sub 2}CO{sub 3}-K{sub 2}CO{sub 3} eutectic electrolytes is effective to avoid these problems. On the other hand, one of the corrosion products, CrO{sub 4}{sup 2-} ion is found to dissolve into electrolyte and accumulated during the long-term MCFC operations. This would affect the performance of MCFC. There, however, are little known data of physical properties of molten carbonate containing alkaline earth carbonates and CrO{sub 4}{sup 2-}. We report the measured and accumulated data for these molten carbonate of electrical conductivity and surface tension to select favorable composition of molten carbonate electrolytes.

  10. Interactions between drops of molten Al-Li alloys and liquid water

    SciTech Connect

    Hyder, M.L.; Nelson, L.S.; Duda, P.M.; Hyndman, D.A.

    1993-08-01

    Sandia National Laboratories, at the request of the Savannah River Technology Center (SRTC), studied the interactions between single drops of molten aluminum-lithium alloys and water. Most experiments were performed with ``B`` alloy (3.1 w/o Li, balance A1). Objectives were to develop experimental procedures for preparing and delivering the melt drops and diagnostics for characterizing the interactions, measure hydrogen generated by the reaction between melt and water, examine debris recovered after the interaction, determine changes in the aqueous phase produced by the melt-water chemical reactions, and determine whether steam explosions occur spontaneously under the conditions studied. Although many H{sub 2} bubbles were generated after the drops entered the water, spontaneous steam explosions never occurred when globules of the ``B`` alloy at temperatures between 700 and 1000C fell freely through water at room temperature, or upon or during subsequent contact with submerged aluminum or stainless steel surfaces. Total amounts of H{sub 2} (STP) increased from about 2 to 9 cm{sup 3}/per gram of melt as initial melt temperature increased over this range of temperatures.

  11. The effect of milk processing on the microstructure of the milk fat globule and rennet induced gel observed using confocal laser scanning microscopy.

    PubMed

    Ong, L; Dagastine, R R; Kentish, S E; Gras, S L

    2010-04-01

    Confocal laser scanning microscopy (CLSM) was successfully used to observe the effect of milk processing on the size and the morphology of the milk fat globule in raw milk, raw ultrafiltered milk, and standardized and pasteurized milk prepared for cheese manufacture (cheese-milk) and commercial pasteurized and homogenized milk. Fat globule size distributions for the milk preparations were analyzed using both image analysis and light scattering and both measurements produced similar data trends. Changes to the native milk fat globule membrane (MFGM) were tracked using a MFGM specific fluorescent stain that allowed MFGM proteins and adsorbed proteins to be differentiated on the fat globule surface. Sodium dodecyl sulfate polyacrylamide gel electrophoresis confirmed the identity of native MFGM proteins isolated from the surface of fat globules within raw, UF retentate, and cheese-milk preparations, whereas only casein was detected on the surface of fat globules in homogenized milk. The microstructure, porosity, and gel strength of the rennet induced gel made from raw milk and cheese-milk was also found to be comparable and significantly different to that made from homogenized milk. Our results highlight the potential use of CLSM as a tool to observe the structural details of the fat globule and associated membrane close to its native environment.

  12. Molten salt reactors - safety options galore

    SciTech Connect

    Gat, U.; Dodds, H.L.

    1997-03-01

    Safety features and attributes of molten salt reactors (MSR) are described. The unique features of fluid fuel reactors of on-line continuous processing and the ability for so-called external cooling result in simple and safe designs with low excess reactivity, low fission product inventory, and small source term. These, in turn, make a criticality accident unlikely and reduce the severity of a loss of coolant to where they are no longer severe accidents. A melt down is not an accident for a reactor that uses molten fuel. The molten salts are stable, non-reactive and efficient heat transfer media that operate at high temperatures at low pressures and are highly compatible with selected structural materials. All these features reduce the accident plethora. Freeze valves can be used for added safety. An ultimate safe reactor (U.S.R) is described with safety features that are passive, inherent and non-tamperable (PINT).

  13. Advances in molten salt chemistry: Vol. 4

    SciTech Connect

    Mamautov, G.; Braunstein, J.

    1981-01-01

    This book presents information on the following topics: electronic properties of solutions of liquid metals and ionic melts; metal-metal halide, metal-chalcogen, and metal-metal solutions; metallic models; the use of high pressure in the study of molten salts; the purpose of high pressure experimentation; melting point curves and phase diagrams; compressibilities and equations of state; electrical conductivity measurements; physical chemistry and electrochemistry of alkali carbonate melts; equilibrium properties of molten carbonates; electrochemical characteristics and corrosion; stability of ceramics; some new molten salt electrolytic processes; sodium metal production by the use of a beta-alumina diaphragm; recovery of metallic sodium or caustic soda and sulfur from flue gas; high temperature electrolysis of water; and LiCl electrolysis by the use of a bipolar liquid metal electrode.

  14. Multipass apparatus for molten salt spectroelectrochemical experiments

    SciTech Connect

    Harward, B.L.; Klatt, L.N.; Mamantov, G.

    1985-07-01

    Although various spectroelectrochemical methods have been applied to studies in molten salt media, the development of techniques and apparatus to improve the optical sensitivity of such measurements is nonexistent. The corrosive nature, moisture sensitivity, and elevated temperatures associated with molten salts often preclude the use of sophisticated optical systems and fragile cell components. A simple apparatus is described for enhancement of the optical signal in molten salt spectroelectrochemical experiments. In this method, the optical beam is redirected through an OTE (optically transparent electrode) several times by a mirror assembly positioned outside the thin-layer cell. The gain in optical sensitivity is defined as the ratio of the response for n passes to that for a single pass. 29 references, 4 figures.

  15. Experimental studies of actinides in molten salts

    SciTech Connect

    Reavis, J.G.

    1985-06-01

    This review stresses techniques used in studies of molten salts containing multigram amounts of actinides exhibiting intense alpha activity but little or no penetrating gamma radiation. The preponderance of studies have used halides because oxygen-containing actinide compounds (other than oxides) are generally unstable at high temperatures. Topics discussed here include special enclosures, materials problems, preparation and purification of actinide elements and compounds, and measurements of various properties of the molten volts. Property measurements discussed are phase relationships, vapor pressure, density, viscosity, absorption spectra, electromotive force, and conductance. 188 refs., 17 figs., 6 tabs.

  16. Studies of metals electroprocessing in molten salts

    NASA Technical Reports Server (NTRS)

    Sadoway, D. R.

    1982-01-01

    Fluid flow patterns in molten salt electrolytes were observed in order to determine how mass transport affects the morphology of the metal deposit. Studies conducted on the same metal, both in aqueous electrolytes in which coherent solid electrodeposits are produced, as well as in transparent molten salt electrolytes are described. Process variables such as current density and composition of the electrolyte are adjusted to change the morphology of the electrodeposit and, thus, to permit the study of the nature of electrolyte flow in relation to the quality of the electrodeposit.

  17. Cathodes for molten-salt batteries

    NASA Technical Reports Server (NTRS)

    Argade, Shyam D.

    1993-01-01

    Viewgraphs of the discussion on cathodes for molten-salt batteries are presented. For the cathode reactions in molten-salt cells, chlorine-based and sulfur-based cathodes reactants have relatively high exchange current densities. Sulfur-based cathodes, metal sulfides, and disulfides have been extensively investigated. Primary thermal batteries of the Li-alloy/FeS2 variety have been available for a number of years. Chlorine based rechargable cathodes were investigated for the pulse power application. A brief introduction is followed by the experimental aspects of research, and the results obtained. Performance projections to the battery system level are discussed and the presentation is summarized with conclusions.

  18. Sodium-tetravalent sulfur molten chloroaluminate cell

    DOEpatents

    Mamantov, Gleb

    1985-04-02

    A sodium-tetravalent sulfur molten chloroaluminate cell with a .beta."-alumina sodium ion conductor having a S-Al mole ratio of above about 0.15 in an acidic molten chloroaluminate cathode composition is disclosed. The cathode composition has an AlCl.sub.3 -NaCl mole percent ratio of above about 70-30 at theoretical full charge. The cell provides high energy densities at low temperatures and provides high energy densities and high power densities at moderate temperatures.

  19. Cathodes for molten-salt batteries

    NASA Astrophysics Data System (ADS)

    Argade, Shyam D.

    1993-02-01

    Viewgraphs of the discussion on cathodes for molten-salt batteries are presented. For the cathode reactions in molten-salt cells, chlorine-based and sulfur-based cathodes reactants have relatively high exchange current densities. Sulfur-based cathodes, metal sulfides, and disulfides have been extensively investigated. Primary thermal batteries of the Li-alloy/FeS2 variety have been available for a number of years. Chlorine based rechargable cathodes were investigated for the pulse power application. A brief introduction is followed by the experimental aspects of research, and the results obtained. Performance projections to the battery system level are discussed and the presentation is summarized with conclusions.

  20. Process for recovering tritium from molten lithium metal

    DOEpatents

    Maroni, Victor A.

    1976-01-01

    Lithium tritide (LiT) is extracted from molten lithium metal that has been exposed to neutron irradiation for breeding tritium within a thermonuclear or fission reactor. The extraction is performed by intimately contacting the molten lithium metal with a molten lithium salt, for instance, lithium chloride - potassium chloride eutectic to distribute LiT between the salt and metal phases. The extracted tritium is recovered in gaseous form from the molten salt phase by a subsequent electrolytic or oxidation step.

  1. Method for recovering hydrocarbons from molten metal halides

    DOEpatents

    Pell, Melvyn B.

    1979-01-01

    In a process for hydrocracking heavy carbonaceous materials by contacting such carbonaceous materials with hydrogen in the presence of a molten metal halide catalyst to produce hydrocarbons having lower molecular weights and thereafter recovering the hydrocarbons so produced from the molten metal halide, an improvement comprising injecting into the spent molten metal halide, a liquid low-boiling hydrocarbon stream is disclosed.

  2. Chemistry and technology of Molten Salt Reactors - history and perspectives

    NASA Astrophysics Data System (ADS)

    Uhlíř, Jan

    2007-01-01

    Molten Salt Reactors represent one of promising future nuclear reactor concept included also in the Generation IV reactors family. This reactor type is distinguished by an extraordinarily close connection between the reactor physics and chemical technology, which is given by the specific features of the chemical form of fuel, representing by molten fluoride salt and circulating through the reactor core and also by the requirements of continuous 'on-line' reprocessing of the spent fuel. The history of Molten Salt Reactors reaches the period of fifties and sixties, when the first experimental Molten Salt Reactors were constructed and tested in ORNL (US). Several molten salt techniques dedicated to fresh molten salt fuel processing and spent fuel reprocessing were studied and developed in those days. Today, after nearly thirty years of discontinuance, a renewed interest in the Molten Salt Reactor technology is observed. Current experimental R&D activities in the area of Molten Salt Reactor technology are realized by a relatively small number of research institutions mainly in the EU, Russia and USA. The main effort is directed primarily to the development of separation processes suitable for the molten salt fuel processing and reprocessing technology. The techniques under development are molten salt/liquid metal extraction processes, electrochemical separation processes from the molten salt media, fused salt volatilization techniques and gas extraction from the molten salt medium.

  3. Globules and pillars in Cygnus X. I. Herschel far-infrared imaging of the Cygnus OB2 environment

    NASA Astrophysics Data System (ADS)

    Schneider, N.; Bontemps, S.; Motte, F.; Blazere, A.; André, Ph.; Anderson, L. D.; Arzoumanian, D.; Comerón, F.; Didelon, P.; Di Francesco, J.; Duarte-Cabral, A.; Guarcello, M. G.; Hennemann, M.; Hill, T.; Könyves, V.; Marston, A.; Minier, V.; Rygl, K. L. J.; Röllig, M.; Roy, A.; Spinoglio, L.; Tremblin, P.; White, G. J.; Wright, N. J.

    2016-06-01

    The radiative feedback of massive stars on molecular clouds creates pillars, globules and other features at the interface between the H II region and molecular cloud. Optical and near-infrared observations from the ground as well as with the Hubble or Spitzer satellites have revealed numerous examples of such cloud structures. We present here Herschel far-infrared observations between 70 μm and 500 μm of the immediate environment of the rich Cygnus OB2 association, performed within the Herschel imaging survey of OB Young Stellar objects (HOBYS) program. All of the observed irradiated structures were detected based on their appearance at 70 μm, and have been classified as pillars, globules, evaporating gasous globules (EGGs), proplyd-like objects, and condensations. From the 70 μm and 160 μm flux maps, we derive the local far-ultraviolet (FUV) field on the photon dominated surfaces. In parallel, we use a census of the O-stars to estimate the overall FUV-field, that is 103-104 G0 (Habing field) close to the central OB cluster (within 10 pc) and decreases down to a few tens G0, in a distance of 50 pc. From a spectral energy distribution (SED) fit to the four longest Herschel wavelengths, we determine column density and temperature maps and derive masses, volume densities and surface densities for these structures. We find that the morphological classification corresponds to distinct physical properties. Pillars and globules are massive (~500 M⊙) and large (equivalent radius r ~ 0.6 pc) structures, corresponding to what is defined as "clumps" for molecular clouds. EGGs and proplyd-likeobjects are smaller (r ~ 0.1 and 0.2 pc) and less massive (~10 and ~30 M⊙). Cloud condensations are small (~0.1 pc), have an average mass of 35 M⊙, are dense (~6 × 104 cm-3), and can thus be described as molecular cloud "cores". All pillars and globules are oriented toward the Cyg OB2 association center and have the longest estimated photoevaporation lifetimes, a few million

  4. Hybrid Molten Salt Reactor (HMSR) System Study

    SciTech Connect

    Woolley, Robert D; Miller, Laurence F

    2014-04-01

    Can the hybrid system combination of (1) a critical fission Molten Salt Reactor (MSR) having a thermal spectrum and a high Conversion Ratio (CR) with (2) an external source of high energy neutrons provide an attractive solution to the world's expanding demand for energy? The present study indicates the answer is an emphatic yes.

  5. Oxygen electrode in molten carbonate fuel cells

    NASA Astrophysics Data System (ADS)

    Dave, B. B.; White, R. E.; Srinivasan, S.; Appleby, A. J.

    1990-12-01

    During this quarter, impedance data were analyzed for an oxygen reduction process in molten carbonate electrolyte and a manuscript, Impedance Analysis for Oxygen Reduction in a Lithium Carbonate Melt: Effects of Partial Pressure of Carbon Dioxide and Temperature, was prepared to be submitted to Journal of the Electrochemical Society for publication.

  6. Accelerators for Subcritical Molten-Salt Reactors

    SciTech Connect

    Johnson, Roland

    2011-08-03

    Accelerator parameters for subcritical reactors have usually been based on using solid nuclear fuel much like that used in all operating critical reactors as well as the thorium burning accelerator-driven energy amplifier proposed by Rubbia et al. An attractive alternative reactor design that used molten salt fuel was experimentally studied at ORNL in the 1960s, where a critical molten salt reactor was successfully operated using enriched U235 or U233 tetrafluoride fuels. These experiments give confidence that an accelerator-driven subcritical molten salt reactor will work better than conventional reactors, having better efficiency due to their higher operating temperature, having the inherent safety of subcritical operation, and having constant purging of volatile radioactive elements to eliminate their accumulation and potential accidental release in dangerous amounts. Moreover, the requirements to drive a molten salt reactor can be considerably relaxed compared to a solid fuel reactor, especially regarding accelerator reliability and spallation neutron targetry, to the point that much of the required technology exists today. It is proposed that Project-X be developed into a prototype commercial machine to produce energy for the world by, for example, burning thorium in India and nuclear waste from conventional reactors in the USA.

  7. Al/Cl2 molten salt battery

    NASA Technical Reports Server (NTRS)

    Giner, J.

    1972-01-01

    Molten salt battery has been developed with theoretical energy density of 5.2 j/kg (650 W-h/lb). Battery, which operates at 150 C, can be used in primary mode or as rechargeable battery. Battery has aluminum anode and chlorine cathode. Electrolyte is mixture of AlCl3, NaCl, and some alkali metal halide such as KCl.

  8. MOLTEN PLUTONIUM FUELED FAST BREEDER REACTOR

    DOEpatents

    Kiehn, R.M.; King, L.D.P.; Peterson, R.E.; Swickard, E.O. Jr.

    1962-06-26

    A description is given of a nuclear fast reactor fueled with molten plutonium containing about 20 kg of plutonium in a tantalum container, cooled by circulating liquid sodium at about 600 to 650 deg C, having a large negative temperature coefficient of reactivity, and control rods and movable reflector for criticality control. (AEC)

  9. Molten metal processes reap profit from waste

    SciTech Connect

    Mather, R.; Steckler, D.; Kimmel, S.; Tanner, A.

    1996-05-01

    Over the past few years, a new tool has been added to the waste-processing arsenal. The use of a reactor filled with molten metal has been proven for dissociating a wide range of organic, organometallic, metallic and inorganic wastes into their constituent elements. Such reactors allow users to manipulate the solution chemistry and operating conditions inside, to reconfigure the dissociated elements into useful products, such as synthesis gas (hydrogen and carbon monoxide), HCl, metal alloys and ceramics, while ensuring high levels of environmental performance. A commercial-scale, molten metal processing unit is being constructed at Hoechst Celanese Corp.`s Bay City, Tex., chemical manufacturing plant. The unit with an estimated capital cost of $25 million, will be constructed, owned and operated by Molten Metal Technology, Inc., and will use MMT`s Catalytic Extraction processing. Once online, the facility will process wastes from Hoechst Celanese`s Gulf Coast plants and from other nearby chemical manufacturers. In addition to processing wastes, the facility will generate a syngas product that will be used onsite as a raw material during chemical manufacturing. Presented are the results of commercial-scale demonstrations using a prototype molten metal reactor for a wide range of industrial waste streams.

  10. Heat transfer behavior of molten nitrate salt

    NASA Astrophysics Data System (ADS)

    Das, Apurba K.; Clark, Michael M.; Teigen, Bard C.; Fiveland, Woodrow A.; Anderson, Mark H.

    2016-05-01

    The usage of molten nitrate salt as heat transfer fluid and thermal storage medium decouples the generation of electricity from the variable nature of the solar resource, allowing CSP plants to avoid curtailment and match production with demand. This however brings some unique challenges for the design of the molten salt central receiver (MSCR). An aspect critical to the use of molten nitrate (60wt%/40wt% - NaNO3/KNO3) salt as heat transfer fluid in the MSCR is to understand its heat transfer behavior. Alstom collaborated with the University of Wisconsin to conduct a series of experiments and experimentally determined the heat transfer coefficients of molten nitrate salt up to high Reynolds number (Re > 2.0E5) and heat flux (q″ > 1000 kW/m2), conditions heretofore not reported in the literature. A cartridge heater instrumented with thermocouples was installed inside a stainless steel pipe to form an annular test section. The test section was installed in the molten salt flow loop at the University of Wisconsin facility, and operated over a range of test conditions to determine heat transfer data that covered the expected operating regime of a practical molten salt receiver. Heat transfer data were compared to widely accepted correlations found in heat transfer literature, including that of Gnielinski. At lower Reynolds number conditions, the results from this work concurred with the molten salt heat transfer data reported in literature and followed the aforementioned correlations. However, in the region of interest for practical receiver design, the correlations did not accurately model the experimentally determined heat transfer data. Two major effects were observed: (i) all other factors remaining constant, the Nusselt numbers gradually plateaued at higher Reynolds number; and (ii) at higher Reynolds number a positive interaction of heat flux on Nusselt number was noted. These effects are definitely not modeled by the existing correlations. In this paper a new

  11. In vivo digestion of bovine milk fat globules: effect of processing and interfacial structural changes. II. Upper digestive tract digestion.

    PubMed

    Gallier, Sophie; Zhu, Xiang Q; Rutherfurd, Shane M; Ye, Aiqian; Moughan, Paul J; Singh, Harjinder

    2013-12-01

    The aim of this research was to study the effect of milk processing on the in vivo upper digestive tract digestion of milk fat globules. Fasted rats were serially gavaged over a 5h period with cream from raw, pasteurised, or pasteurised and homogenised milk. Only a few intact dietary proteins and peptides were present in the small intestinal digesta. Significantly (P<0.05) more longer chain (C≥10) fatty acids were present in the digesta of rats gavaged with raw (448 mg g(-1) digesta dry matter (DDM)) and homogenised creams (528 mg g(-1) DDM), as compared to pasteurised and homogenised cream (249 mg g(-1) DDM). Microscopy techniques were used to investigate the structural changes during digestion. Liquid-crystalline lamellar phases surrounding the fat globules, fatty acid soap crystals and lipid-mucin interactions were evident in all small intestinal digesta. Overall, the pasteurised and homogenised cream appeared to be digested to a greater extent. PMID:23871080

  12. Redox proteomics of fat globules unveils broad protein lactosylation and compositional changes in milk samples subjected to various technological procedures.

    PubMed

    Arena, Simona; Renzone, Giovanni; Novi, Gianfranco; Scaloni, Andrea

    2011-10-19

    The Maillard reaction between lactose and proteins occurs during thermal treatment of milk and lactosylated β-lactoglobulin, α-lactalbumin and caseins have widely been used to monitor the quality of dairy products. We recently demonstrated that a number of other whey milk proteins essential for nutrient delivery, defense against bacteria/virus and cellular proliferation become lactosylated during milk processing. The extent of their modification is associated with the harshness of product manufacturing. Since fat globule proteins are also highly important for the health-beneficial properties of milk, an evaluation of their lactosylation is crucial for a complete understanding of aliment nutritional characteristics. This is more important when milk is the unique dietary source, as in the infant diet. To this purpose, a sequential proteomic procedure involving an optimized milk fat globule (MFG) preparation/electrophoretic resolution, shot-gun analysis of gel portions for protein identification, selective trapping of lactosylated peptides by phenylboronate chromatography and their analysis by nanoLC-ESI-electron transfer dissociation (ETD) tandem MS was used for systematic characterization of fat globule proteins in milk samples subjected to various manufacturing procedures. Significant MFG protein compositional changes were observed between samples, highlighting the progressive adsorption of caseins and whey proteins on the fat globule surface as result of the technological process used. A significant lactosylation of MFG proteins was observed in ultra-high temperature sterilized and powdered for infant nutrition milk preparations, which well paralleled with the harshness of thermal treatment. Globally, this study allowed the identification of novel 157 non-redundant modification sites and 35 MFG proteins never reported so far as being lactosylated, in addition to the 153 ones ascertained here as present on other 21 MFG-adsorbed proteins whose nature was already

  13. Feet sunk in molten aluminium: The burn and its prevention.

    PubMed

    Alonso-Peña, David; Arnáiz-García, María Elena; Valero-Gasalla, Javier Luis; Arnáiz-García, Ana María; Campillo-Campaña, Ramón; Alonso-Peña, Javier; González-Santos, Jose María; Fernández-Díaz, Alaska Leonor; Arnáiz, Javier

    2015-08-01

    Nowadays, despite improvements in safety rules and inspections in the metal industry, foundry workers are not free from burn accidents. Injuries caused by molten metals include burns secondary to molten iron, aluminium, zinc, copper, brass, bronze, manganese, lead and steel. Molten aluminium is one of the most common causative agents of burns (60%); however, only a few publications exist concerning injuries from molten aluminium. The main mechanisms of lesion from molten aluminium include direct contact of the molten metal with the skin or through safety apparel, or when the metal splash burns through the pants and rolls downward along the leg. Herein, we report three cases of deep dermal burns after 'soaking' the foot in liquid aluminium and its evolutive features. This paper aims to show our experience in the management of burns due to molten aluminium. We describe the current management principles and the key features of injury prevention.

  14. Les transfusions de globules rouges chez le nouveau-né : Des directives révisées

    PubMed Central

    2002-01-01

    En général, depuis dix ans, les professionnels de la santé qui soignent des nouveau-nés à haut risque dans des unités de soins intensifs néonatals sont plus restrictifs dans leur utilisation de transfusions de globules rouges. Le présent énoncé est conçu pour ceux qui soignent des nouveau-nés à haut risque (des prématurés aux nouveau-nés d’un mois). Il vise à fournir des directives pour réduire l’incidence d’anémie chez les nourrissons prématurés et à terme, à repérer des stratégies pour réduire le besoin de transfusions de globules rouges et à limiter l’exposition à des donneurs au sein de cette population. Des recommandations portant sur les transfusions de globules rouges sont incluses.

  15. Identification of Escherichia coli F4ac-binding proteins in porcine milk fat globule membrane

    PubMed Central

    Novakovic, Predrag; Huang, Yanyun Y.; Lockerbie, Betty; Shahriar, Farshid; Kelly, John; Gordon, John R.; Middleton, Dorothy M.; Loewen, Matthew E.; Kidney, Beverly A.; Simko, Elemir

    2015-01-01

    F4ac-positive enterotoxigenic Escherichia coli (ETEC) must attach to the intestinal mucosa to cause diarrhea in piglets. Prevention of bacterial attachment to the intestinal mucosa is the most effective defense against ETEC-induced diarrhea. Porcine milk fat globule membranes (MFGM) were shown to be able to inhibit attachment of ETEC to the intestinal brush border; however, the specific components of porcine MFGM that inhibited attachment of ETEC to enterocytes were not identified. Accordingly, the purpose of this study was to identify F4ac-binding MFGM proteins by overlay Western blot and affinity chromatography. The proteome of porcine MFGM was characterized and the following F4ac-binding proteins were detected by overlay Western blot and affinity chromatography: lactadherin, butyrophilin, adipophilin, acyl-CoA synthetase 3, and fatty acid-binding protein 3. The biological function of these proteins was not investigated but it is possible that their interaction with F4ac fimbria interferes with bacterial attachment and colonization. PMID:25852227

  16. Identification of Escherichia coli F4ac-binding proteins in porcine milk fat globule membrane.

    PubMed

    Novakovic, Predrag; Huang, Yanyun Y; Lockerbie, Betty; Shahriar, Farshid; Kelly, John; Gordon, John R; Middleton, Dorothy M; Loewen, Matthew E; Kidney, Beverly A; Simko, Elemir

    2015-04-01

    F4ac-positive enterotoxigenic Escherichia coli (ETEC) must attach to the intestinal mucosa to cause diarrhea in piglets. Prevention of bacterial attachment to the intestinal mucosa is the most effective defense against ETEC-induced diarrhea. Porcine milk fat globule membranes (MFGM) were shown to be able to inhibit attachment of ETEC to the intestinal brush border; however, the specific components of porcine MFGM that inhibited attachment of ETEC to enterocytes were not identified. Accordingly, the purpose of this study was to identify F4ac-binding MFGM proteins by overlay Western blot and affinity chromatography. The proteome of porcine MFGM was characterized and the following F4ac-binding proteins were detected by overlay Western blot and affinity chromatography: lactadherin, butyrophilin, adipophilin, acyl-CoA synthetase 3, and fatty acid-binding protein 3. The biological function of these proteins was not investigated but it is possible that their interaction with F4ac fimbria interferes with bacterial attachment and colonization.

  17. Elongated prismatic magnetite crystals in ALH84001 carbonate globules: potential Martian magnetofossils.

    PubMed

    Thomas-Keprta, K L; Bazylinski, D A; Kirschvink, J L; Clemett, S J; McKay, D S; Wentworth, S J; Vali, H; Gibson, E K; Romanek, C S

    2000-12-01

    Using transmission electron microscopy (TEM), we have analyzed magnetite (Fe3O4) crystals acid-extracted from carbonate globules in Martian meteorite ALH84001. We studied 594 magnetites from ALH84001 and grouped them into three populations on the basis of morphology: 389 were irregularly shaped, 164 were elongated prisms, and 41 were whisker-like. As a possible terrestrial analog for the ALH84001 elongated prisms, we compared these magnetites with those produced by the terrestrial magnetotactic bacteria strain MV-1. By TEM again, we examined 206 magnetites recovered from strain MV-1 cells. Natural (Darwinian) selection in terrestrial magnetotactic bacteria appears to have resulted in the formation of intracellular magnetite crystals having the physical and chemical properties that optimize their magnetic moment. In this study, we describe six properties of magnetite produced by biologically controlled mechanisms (e.g., magnetotactic bacteria), properties that, collectively, are not observed in any known population of inorganic magnetites. These criteria can be used to distinguish one of the modes of origin for magnetites from samples with complex or unknown histories. Of the ALH84001 magnetites that we have examined, the elongated prismatic magnetite particles (similar to 27% of the total) are indistinguishable from the MV-1 magnetites in five of these six characteristics observed for biogenically controlled mineralization of magnetite crystals. PMID:11543573

  18. Metabolism of milk fat globule membrane components by nonstarter lactic acid bacteria isolated from cheese.

    PubMed

    Moe, K M; Porcellato, D; Skeie, S

    2013-02-01

    The objective of this study was to investigate how components present in the milk fat globule membrane (MFGM) may be used for growth and survival by cheese-ripening lactobacilli. This was achieved by analyzing metabolites produced during incubation on appropriate media. The lactobacilli investigated were able to utilize components from the MFGM throughout a 24-d incubation period. We observed an apparent connection between the higher proteolytic activity of Lactobacillus paracasei INF448 and its ability to grow in the MFGM media after depletion of readily available sugars. All the studied strains produced large amounts of acetate when grown on an acylated aminosugar, presumably from deacetylation of the monosaccharides. Growth of Lb. plantarum INF15D on D-galactose resulted in a metabolic shift, expressed as different fates of the produced pyruvate, compared with growth on the other monosaccharides. For Lb. plantarum INF15D, the presence of D-galactose also seemed to initiate degradation of some amino acids known to take part in energy production, specifically Arg and Tyr.

  19. Identification of Escherichia coli F4ac-binding proteins in porcine milk fat globule membrane.

    PubMed

    Novakovic, Predrag; Huang, Yanyun Y; Lockerbie, Betty; Shahriar, Farshid; Kelly, John; Gordon, John R; Middleton, Dorothy M; Loewen, Matthew E; Kidney, Beverly A; Simko, Elemir

    2015-04-01

    F4ac-positive enterotoxigenic Escherichia coli (ETEC) must attach to the intestinal mucosa to cause diarrhea in piglets. Prevention of bacterial attachment to the intestinal mucosa is the most effective defense against ETEC-induced diarrhea. Porcine milk fat globule membranes (MFGM) were shown to be able to inhibit attachment of ETEC to the intestinal brush border; however, the specific components of porcine MFGM that inhibited attachment of ETEC to enterocytes were not identified. Accordingly, the purpose of this study was to identify F4ac-binding MFGM proteins by overlay Western blot and affinity chromatography. The proteome of porcine MFGM was characterized and the following F4ac-binding proteins were detected by overlay Western blot and affinity chromatography: lactadherin, butyrophilin, adipophilin, acyl-CoA synthetase 3, and fatty acid-binding protein 3. The biological function of these proteins was not investigated but it is possible that their interaction with F4ac fimbria interferes with bacterial attachment and colonization. PMID:25852227

  20. Discovery of a Hot Corino in the Bok Globule B335

    NASA Astrophysics Data System (ADS)

    Imai, Muneaki; Sakai, Nami; Oya, Yoko; López-Sepulcre, Ana; Watanabe, Yoshimasa; Ceccarelli, Cecilia; Lefloch, Bertrand; Caux, Emmanuel; Vastel, Charlotte; Kahane, Claudine; Sakai, Takeshi; Hirota, Tomoya; Aikawa, Yuri; Yamamoto, Satoshi

    2016-10-01

    We report the first evidence of a hot corino in a Bok globule. This is based on ALMA observations in the 1.2 mm band toward the low-mass Class 0 protostar IRAS 19347+0727 in B335. Saturated complex organic molecules (COMs), CH3CHO, HCOOCH3, and NH2CHO, are detected in a compact region within a few 10 au around the protostar. Additionally, CH3OCH3, C2H5OH, C2H5CN, and CH3COCH3 are tentatively detected. Carbon-chain related molecules, CCH and c-C3H2, are also found in this source, whose distributions are extended over a scale of a few 100 au. On the other hand, sulfur-bearing molecules CS, SO, and SO2 have both compact and extended components. Fractional abundances of the COMs relative to H2 are found to be comparable to those in known hot corino sources. Though the COMs lines are as broad as 5–8 km s‑1, they do not show obvious rotation motion in the present observation. Thus, the COMs mainly exist in a structure whose distribution is much smaller than the synthesized beam (0.″58 × 0.″52).

  1. ARE LARGE, COMETARY-SHAPED PROPLYDS REALLY (FREE-FLOATING) EVAPORATING GAS GLOBULES?

    SciTech Connect

    Sahai, R.; Guesten, R.; Morris, M. R.

    2012-12-20

    We report the detection of strong and compact molecular line emission (in the CO J = 3-2, 4-3, 6-5, 7-6, {sup 13}CO J = 3-2, HCN, and HCO{sup +} J = 4-3 transitions) from a cometary-shaped object (Carina-frEGG1) in the Carina star-forming region (SFR) previously classified as a photoevaporating protoplanetary disk (proplyd). We derive a molecular mass of 0.35 M{sub Sun} for Carina-frEGG1, which shows that it is not a proplyd, but belongs to a class of free-floating evaporating gas globules (frEGGs) recently found in the Cygnus SFR by Sahai et al. Archival adaptive optics near-IR (Ks) images show a central hourglass-shaped nebula. The derived source luminosity (about 8-18 L{sub Sun }), the hourglass morphology, and the presence of collimated jets seen in Hubble Space Telescope images imply the presence of a jet-driving, young, low-mass star deeply embedded in the dust inside Carina-frEGG1. Our results suggest that the true nature of many or most such cometary-shaped objects seen in massive SFRs and previously labeled as proplyds has been misunderstood, and that these are really frEGGs.

  2. Complement-dependent cytotoxicity crossmatch.

    PubMed

    Peña, Jeremy Ryan; Fitzpatrick, Donna; Saidman, Susan L

    2013-01-01

    The complement-dependent cytotoxic crossmatch is an informative test that detects alloantibodies in pre- and post-transplant patients, which may dictate clinical management of transplant patients. While challenging to perform, the cytotoxic crossmatch represents the only assay that provides direct evidence for the presence of potentially pathologic (i.e., cytotoxic) alloantibodies. The cytotoxic crossmatch combines patient (recipient) serum and donor cells. If donor-reactive alloantibodies are present in patient serum, these antibodies can bind donor cells. Antibody-antigen complexes, in turn, can activate the complement cascade, leading to complement-mediated cytotoxicity. Two commonly performed cytotoxic crossmatches, using donor lymphocytes as target cells, are described.

  3. Dynamics of the Molten Contact Line

    NASA Technical Reports Server (NTRS)

    Sonin, Ain A.; Duthaler, Gregg; Liu, Michael; Torresola, Javier; Qiu, Taiqing

    1999-01-01

    The purpose of this program is to develop a basic understanding of how a molten material front spreads over a solid that is below its melting point, arrests, and freezes. Our hope is that the work will contribute toward a scientific knowledge base for certain new applications involving molten droplet deposition, including the "printing" of arbitrary three-dimensional objects by precise deposition of individual molten microdrops that solidify after impact. Little information is available at this time on the capillarity-driven motion and arrest of molten contact line regions. Schiaffino and Sonin investigated the arrest of the contact line of a molten microcrystalline wax spreading over a subcooled solid "target" of the same material. They found that contact line arrest takes place at an apparent liquid contact angle that depends primarily on the Stefan number S=c(T(sub f) -T(sub t)/L based on the temperature difference between the fusion point and the target temperature, and proposed that contact line arrest occurs when the liquid's dynamic contact angle approaches the angle of attack of the solidification front just behind the contact line. They also showed, however, that the conventional continuum equations and boundary conditions have no meaningful solution for this angle. The solidification front angle is determined by the heat flux just behind the contact line, and the heat flux is singular at that point. By comparing experiments with numerical computations, Schiaffino and Sonin estimated that the conventional solidification model must break down within a distance of order 0.1 - 1 microns of the contact line. The physical mechanism for this breakdown is as yet undetermined, and no first-principles theory exists for the contact angle at arrest. Schiaffino and Sonin also presented a framework for understanding how to moderate Weber number molten droplet deposition in terms of similarity laws and experimentation. The study is based on experiments with three molten

  4. Molten uranium dioxide structure and dynamics

    SciTech Connect

    Skinner, L. B.; Parise, J. B.; Benmore, C. J.; Weber, J. K.R.; Williamson, M. A.; Tamalonis, A.; Hebden, A.; Wiencek, T.; Alderman, O. L.G.; Guthrie, M.; Leibowitz, L.

    2014-11-21

    Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.

  5. Molten uranium dioxide structure and dynamics

    DOE PAGES

    Skinner, L. B.; Parise, J. B.; Benmore, C. J.; Weber, J. K.R.; Williamson, M. A.; Tamalonis, A.; Hebden, A.; Wiencek, T.; Alderman, O. L.G.; Guthrie, M.; et al

    2014-11-21

    Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. Onmore » melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.« less

  6. Molten uranium dioxide structure and dynamics.

    PubMed

    Skinner, L B; Benmore, C J; Weber, J K R; Williamson, M A; Tamalonis, A; Hebden, A; Wiencek, T; Alderman, O L G; Guthrie, M; Leibowitz, L; Parise, J B

    2014-11-21

    Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts. PMID:25414311

  7. Method and apparatus for spraying molten materials

    DOEpatents

    Glovan, Ronald J.; Tierney, John C.; McLean, Leroy L.; Johnson, Lawrence L.; Nelson, Gordon L.; Lee, Ying-Ming

    1996-01-01

    A metal spray apparatus is provided with a supersonic nozzle. Molten metal is injected into a gas stream flowing through the nozzle under pressure. By varying the pressure of the injected metal, the droplet can be made in various selected sizes with each selected size having a high degree of size uniformity. A unique one piece graphite heater provides easily controlled uniformity of temperature in the nozzle and an attached tundish which holds the pressurized molten metal. A unique U-shaped gas heater provides extremely hot inlet gas temperatures to the nozzle. A particularly useful application of the spray apparatus is coating of threads of a fastener with a shape memory alloy. This permits a fastener to be easily inserted and removed but provides for a secure locking of the fastener in high temperature environments.

  8. Method and apparatus for spraying molten materials

    DOEpatents

    Glovan, R.J.; Tierney, J.C.; McLean, L.L.; Johnson, L.L.; Nelson, G.L.; Lee, Y.M.

    1996-06-25

    A metal spray apparatus is provided with a supersonic nozzle. Molten metal is injected into a gas stream flowing through the nozzle under pressure. By varying the pressure of the injected metal, the droplet can be made in various selected sizes with each selected size having a high degree of size uniformity. A unique one piece graphite heater provides easily controlled uniformity of temperature in the nozzle and an attached tundish which holds the pressurized molten metal. A unique U-shaped gas heater provides extremely hot inlet gas temperatures to the nozzle. A particularly useful application of the spray apparatus is coating of threads of a fastener with a shape memory alloy. This permits a fastener to be easily inserted and removed but provides for a secure locking of the fastener in high temperature environments. 12 figs.

  9. Molten uranium dioxide structure and dynamics.

    PubMed

    Skinner, L B; Benmore, C J; Weber, J K R; Williamson, M A; Tamalonis, A; Hebden, A; Wiencek, T; Alderman, O L G; Guthrie, M; Leibowitz, L; Parise, J B

    2014-11-21

    Uranium dioxide (UO2) is the major nuclear fuel component of fission power reactors. A key concern during severe accidents is the melting and leakage of radioactive UO2 as it corrodes through its zirconium cladding and steel containment. Yet, the very high temperatures (>3140 kelvin) and chemical reactivity of molten UO2 have prevented structural studies. In this work, we combine laser heating, sample levitation, and synchrotron x-rays to obtain pair distribution function measurements of hot solid and molten UO2. The hot solid shows a substantial increase in oxygen disorder around the lambda transition (2670 K) but negligible U-O coordination change. On melting, the average U-O coordination drops from 8 to 6.7 ± 0.5. Molecular dynamics models refined to this structure predict higher U-U mobility than 8-coordinated melts.

  10. Molten metal holder furnace and casting system incorporating the molten metal holder furnace

    DOEpatents

    Kinosz, Michael J.; Meyer, Thomas N.

    2003-02-11

    A bottom heated holder furnace (12) for containing a supply of molten metal includes a storage vessel (30) having sidewalls (32) and a bottom wall (34) defining a molten metal receiving chamber (36). A furnace insulating layer (42) lines the molten metal receiving chamber (36). A thermally conductive heat exchanger block (54) is located at the bottom of the molten metal receiving chamber (36) for heating the supply of molten metal. The heat exchanger block (54) includes a bottom face (65), side faces (66), and a top face (67). The heat exchanger block (54) includes a plurality of electrical heaters (70) extending therein and projecting outward from at least one of the faces of the heat exchanger block (54), and further extending through the furnace insulating layer (42) and one of the sidewalls (32) of the storage vessel (30) for connection to a source of electrical power. A sealing layer (50) covers the bottom face (65) and side faces (66) of the heat exchanger block (54) such that the heat exchanger block (54) is substantially separated from contact with the furnace insulating layer (42).

  11. Molten Glass for Thermal Storage: Advanced Molten Glass for Heat Transfer and Thermal Energy Storage

    SciTech Connect

    2012-01-01

    HEATS Project: Halotechnics is developing a high-temperature thermal energy storage system using a new thermal-storage and heat-transfer material: earth-abundant and low-melting-point molten glass. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun is not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. Halotechnics new thermal storage material targets a price that is potentially cheaper than the molten salt used in most commercial solar thermal storage systems today. It is also extremely stable at temperatures up to 1200°C—hundreds of degrees hotter than the highest temperature molten salt can handle. Being able to function at high temperatures will significantly increase the efficiency of turning heat into electricity. Halotechnics is developing a scalable system to pump, heat, store, and discharge the molten glass. The company is leveraging technology used in the modern glass industry, which has decades of experience handling molten glass.

  12. Advanced heat exchanger development for molten salts

    DOE PAGES

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet materialmore » in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.« less

  13. Advanced heat exchanger development for molten salts

    SciTech Connect

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet material in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.

  14. Molten salt battery having inorganic paper separator

    DOEpatents

    Walker, Jr., Robert D.

    1977-01-01

    A high temperature secondary battery comprises an anode containing lithium, a cathode containing a chalcogen or chalcogenide, a molten salt electrolyte containing lithium ions, and a separator comprising a porous sheet comprising a homogenous mixture of 2-20 wt.% chrysotile asbestos fibers and the remainder inorganic material non-reactive with the battery components. The non-reactive material is present as fibers, powder, or a fiber-powder mixture.

  15. Molten Wax As A Dust Control Agent

    SciTech Connect

    Carter, E.E.

    2008-07-01

    Molten wax shows considerable promise as a fixative and dust control agent in demolition of radioactively contaminated facilities. Sticky molten wax, modified with special surfactants and wetting agents, is capable of not only coating materials but also penetrating into friable or dusty materials and making them incapable of becoming airborne during demolition. Wax also shows significant promise for stabilization of waste residuals that may be contained in buildings undergoing demolition. Some of the building materials that have been tested to date include concrete, wood, sheet-rock, fiber insulation, lime, rock, and paper. Protective clothing, clay, sand, sulfur, and bentonite clay have been tested as surrogates for certain waste materials that may be encountered during building demolition. The paper describes several potential applications of molten wax for dust control in demolition of radioactive contaminated facilities. As a case-study, this paper describes a research test performed for a pipeline closure project being completed by the Idaho Cleanup Project at the Idaho National Laboratory. The project plans to excavate and remove a section of buried Duriron drain piping containing highly radioactive and friable and 'flighty' waste residuals. A full-scale pipeline mockup containing simulated waste was buried in sand to simulate the direct-buried subsurface condition of the subject piping. The pipeline was pre-heated by drawing hot air through the line with a HEPA vacuum blower unit. Molten wax was pumped into the line and allowed to cool. The line was then broken apart in various places to evaluate the permeation performance of the wax. The wax fully permeated all the surrogate materials rendering them non-friable with a consistency similar to modeling clay. Based on the performance during the mockup, it is anticipated that the wax will be highly effective in controlling the spread of radiological contamination during pipe demolition activities. A larger test

  16. Molten salt destruction of base hydrolysate

    SciTech Connect

    Watkins, B.E.; Kanna, R.L.; Chambers, R.D.; Upadhye, R.S.; Promeda, C.O.

    1996-10-01

    There is a great need for alternatives to open burn/open detonation of explosives and propellants from dismantled munitions. LANL has investigated the use of base hydrolysis for the demilitarization of explosives. Hydrolysates of Comp B, Octol, Tritonal, and PBXN-109 were processed in the pilot molten salt unit (in building 191). NOx and CO emissions were found to be low, except for CO from PBXN-109 processing. This report describes experimental results of the destruction of the base hydrolysates.

  17. Thermal Characterization of Molten Salt Systems

    SciTech Connect

    Toni Y. Gutknecht; Guy L. Fredrickson

    2011-09-01

    The phase stability of molten salts in an electrorefiner (ER) may be adversely affected by the buildup of sodium, fission products, and transuranics in the electrolyte. Potential situations that need to be avoided are the following: (1) salt freezing due to an unexpected change in the liquidus temperature, (2) phase separation or non-homogeneity of the molten salt due to the precipitation of solids or formation of immiscible liquids, and (3) any mechanism that can result in the separation and concentration of fissile elements from the molten salt. Any of these situations would result in an off-normal condition outside the established safety basis for electrorefiner (ER) operations. The stability (and homogeneity) of the phases can potentially be monitored through the thermal characterization of the salts, which can be a function of impurity concentration. This report describes the experimental results of typical salts compositions, which consist of chlorides of potassium, lithium, strontium, samarium, praseodymium, lanthanum, barium, cerium, cesium, neodymium, sodium and gadolinium chlorides as a surrogate for both uranium and plutonium, used for the processing of used nuclear fuels.

  18. A Molten Salt Lithium-Oxygen Battery.

    PubMed

    Giordani, Vincent; Tozier, Dylan; Tan, Hongjin; Burke, Colin M; Gallant, Betar M; Uddin, Jasim; Greer, Julia R; McCloskey, Bryan D; Chase, Gregory V; Addison, Dan

    2016-03-01

    Despite the promise of extremely high theoretical capacity (2Li + O2 ↔ Li2O2, 1675 mAh per gram of oxygen), many challenges currently impede development of Li/O2 battery technology. Finding suitable electrode and electrolyte materials remains the most elusive challenge to date. A radical new approach is to replace volatile, unstable and air-intolerant organic electrolytes common to prior research in the field with alkali metal nitrate molten salt electrolytes and operate the battery above the liquidus temperature (>80 °C). Here we demonstrate an intermediate temperature Li/O2 battery using a lithium anode, a molten nitrate-based electrolyte (e.g., LiNO3-KNO3 eutectic) and a porous carbon O2 cathode with high energy efficiency (∼95%) and improved rate capability because the discharge product, lithium peroxide, is stable and moderately soluble in the molten salt electrolyte. The results, supported by essential state-of-the-art electrochemical and analytical techniques such as in situ pressure and gas analyses, scanning electron microscopy, rotating disk electrode voltammetry, demonstrate that Li2O2 electrochemically forms and decomposes upon cycling with discharge/charge overpotentials as low as 50 mV. We show that the cycle life of such batteries is limited only by carbon reactivity and by the uncontrolled precipitation of Li2O2, which eventually becomes electrically disconnected from the O2 electrode. PMID:26871485

  19. A Molten Salt Lithium-Oxygen Battery.

    PubMed

    Giordani, Vincent; Tozier, Dylan; Tan, Hongjin; Burke, Colin M; Gallant, Betar M; Uddin, Jasim; Greer, Julia R; McCloskey, Bryan D; Chase, Gregory V; Addison, Dan

    2016-03-01

    Despite the promise of extremely high theoretical capacity (2Li + O2 ↔ Li2O2, 1675 mAh per gram of oxygen), many challenges currently impede development of Li/O2 battery technology. Finding suitable electrode and electrolyte materials remains the most elusive challenge to date. A radical new approach is to replace volatile, unstable and air-intolerant organic electrolytes common to prior research in the field with alkali metal nitrate molten salt electrolytes and operate the battery above the liquidus temperature (>80 °C). Here we demonstrate an intermediate temperature Li/O2 battery using a lithium anode, a molten nitrate-based electrolyte (e.g., LiNO3-KNO3 eutectic) and a porous carbon O2 cathode with high energy efficiency (∼95%) and improved rate capability because the discharge product, lithium peroxide, is stable and moderately soluble in the molten salt electrolyte. The results, supported by essential state-of-the-art electrochemical and analytical techniques such as in situ pressure and gas analyses, scanning electron microscopy, rotating disk electrode voltammetry, demonstrate that Li2O2 electrochemically forms and decomposes upon cycling with discharge/charge overpotentials as low as 50 mV. We show that the cycle life of such batteries is limited only by carbon reactivity and by the uncontrolled precipitation of Li2O2, which eventually becomes electrically disconnected from the O2 electrode.

  20. Comparative proteomics of milk fat globule membrane proteins from transgenic cloned cattle.

    PubMed

    Sui, Shunchao; Zhao, Jie; Wang, Jianwu; Zhang, Ran; Guo, Chengdong; Yu, Tian; Li, Ning

    2014-01-01

    The use of transgenic livestock is providing new methods for obtaining pharmaceutically useful proteins. However, the protein expression profiles of the transgenic animals, including expression of milk fat globule membrane (MFGM) proteins, have not been well characterized. In this study, we compared the MFGM protein expression profile of the colostrum and mature milk from three lines of transgenic cloned (TC) cattle, i.e., expressing recombinant human α-lactalbumin (TC-LA), lactoferrin (TC-LF) or lysozyme (TC-LZ) in the mammary gland, with those from cloned non-transgenic (C) and conventionally bred normal animals (N). We identified 1, 225 proteins in milk MFGM, 166 of which were specifically expressed only in the TC-LA group, 265 only in the TC-LF group, and 184 only in the TC-LZ group. There were 43 proteins expressed only in the transgenic cloned animals, but the concentrations of these proteins were below the detection limit of silver staining. Functional analysis also showed that the 43 proteins had no obvious influence on the bovine mammary gland. Quantitative comparison revealed that MFGM proteins were up- or down-regulated more than twofold in the TC and C groups compared to N group: 126 in colostrum and 77 in mature milk of the TC-LA group; 157 in colostrum and 222 in mature milk of the TC-LF group; 49 in colostrum and 98 in mature milk of the TC-LZ group; 98 in colostrum and 132 in mature milk in the C group. These up- and down-regulated proteins in the transgenic animals were not associated with a particular biological function or pathway, which appears that expression of certain exogenous proteins has no general deleterious effects on the cattle mammary gland.

  1. SUBMILLIMETER ARRAY AND SPITZER OBSERVATIONS OF BOK GLOBULE CB 17: A CANDIDATE FIRST HYDROSTATIC CORE?

    SciTech Connect

    Chen Xuepeng; Arce, Hector G.; Dunham, Michael M.; Zhang Qizhou; Bourke, Tyler L.; Launhardt, Ralf; Schmalzl, Markus; Henning, Thomas

    2012-06-01

    We present high angular resolution Submillimeter Array (SMA) and Spitzer observations toward the Bok globule CB 17. SMA 1.3 mm dust continuum images reveal within CB 17 two sources with an angular separation of {approx}21'' ({approx}5250 AU at a distance of {approx}250 pc). The northwestern continuum source, referred to as CB 17 IRS, dominates the infrared emission in the Spitzer images, drives a bipolar outflow extending in the northwest-southeast direction, and is classified as a low-luminosity Class 0/I transition object (L{sub bol} {approx} 0.5 L{sub Sun }). The southeastern continuum source, referred to as CB 17 MMS, has faint dust continuum emission in the SMA 1.3 mm observations ({approx}6{sigma} detection; {approx}3.8 mJy), but is not detected in the deep Spitzer infrared images at wavelengths from 3.6 to 70 {mu}m. Its bolometric luminosity and temperature, estimated from its spectral energy distribution, are {<=}0.04 L{sub Sun} and {<=}16 K, respectively. The SMA CO (2-1) observations suggest that CB 17 MMS may drive a low-velocity molecular outflow ({approx}2.5 km s{sup -1}), extending in the east-west direction. Comparisons with prestellar cores and Class 0 protostars suggest that CB 17 MMS is more evolved than prestellar cores but less evolved than Class 0 protostars. The observed characteristics of CB 17 MMS are consistent with the theoretical predictions from radiative/magnetohydrodynamical simulations of a first hydrostatic core, but there is also the possibility that CB 17 MMS is an extremely low luminosity protostar deeply embedded in an edge-on circumstellar disk. Further observations are needed to study the properties of CB 17 MMS and to address more precisely its evolutionary stage.

  2. Shocked and Scorched - Free-Floating Evaporating Gas Globules and Star Formation

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra; Morris, Mark R.; Claussen, Mark J.

    2014-07-01

    Massive stars have a strong feedback effect on their environment, via their winds, UV radiation, and ultimately, supernova blast waves, all of which can alter the likelihood for the formation of stars in nearby clouds and limit the accretion process of nearby protostars. Free-floating Evaporating Gaseous Globules, or frEGGs, are a newly recognized class of stellar nurseries embedded within the giant HII regions found in massive star-formation region (MSFRs). We recently discovered the prototype frEGG in the Cygnus MSFR with HST. Further investigation using the Spitzer and Herschel archives have revealed a much larger number (>50) in Cygnus and other MSFRs. Our molecular-line observations of these show the presence of dense clouds with total masses of cool molecular gas exceeding 0.5 to a few Msun associated with these objects, thereby disproving the initial hypothesis based on their morphology that these have an origin similar to the proplyds (cometary-shaped photoevaporating protoplanetary disks) found in Orion. We report the results of our molecular-line studies and detailed high-resolution optical (with HST) or near-IR (with AO at the Keck Observatory) imaging of a few frEGGs in Cygnus, Carina and the W5 MSFRs. The images show the presence of young stars with associated outflow cavities and/or jets in the heads of the tadpole-shaped frEGGs. These results support our hypothesis that frEGGs are density concentrations originating in giant molecular clouds, that, when subject to the compression by the strong winds and ionization from massive stars in these MSFRs, become active star-forming cores. In summary, by virtue of their distinct, isolated morphologies, frEGGs offer us a clean probe of triggered star formation on small scales in the vicinity of massive stars.

  3. Milk fat globule E-8 and interleukin 17 in systemic lupus erythematosus: partners in crime?

    PubMed Central

    Elgengehy, Fatema; Niazy, Marwa; Ghoneim, Shada

    2016-01-01

    Objectives Systemic lupus erythematosus (SLE) is a multi-factorial, autoimmune disease with a wide array of manifestations. The pro-inflammatory cytokine interleukin (IL)-17 has been implicated in the inflammatory response and tissue damage in SLE; however, its correlation with disease activity is still questionable. Meanwhile, efficient clearance of apoptotic cells is required for immune tolerance. An abnormally low or high level of milk fat globule (MFG-E8) can result in impaired apoptotic cell clearance and the subsequent autoimmune response. In this study, we endeavoured to compare the levels of MFG-E8 and IL-17 in SLE patients and healthy controls and to reveal the alleged association of these levels with SLE disease activity. Material and methods Serum samples from 57 SLE patients and 30 healthy control subjects were examined for quantitation of MFG-E8 and IL-17 levels using ELISA. Systemic lupus erythematosus disease activity was calculated using the SLE Disease Activity Index (SLEDAI). Clinical manifestations and laboratory findings of the patients were also recorded. Results We report that serum MFG-E8 levels were significantly elevated in the sera of SLE patients compared to healthy controls (p-value = 0.019). Likewise, IL-17 levels were higher in SLE patients (p-value < 0.001). A positive correlation was revealed between MFG-E8 level and proteinuria. Surprisingly, there was a poor correlation between disease activity and the levels of either IL-17 or MFG-E8. Conclusions Although serum MFG-E8 and IL-17 levels were higher in SLE patients than in normal controls, our results indicate that they cannot accurately reflect the disease activity. Meanwhile, further studies are needed to assess MFG-E8 and IL-17 as potential therapeutic targets in SLE patients. PMID:27407263

  4. Study of magnetic field geometry and extinction in Bok globule CB130

    NASA Astrophysics Data System (ADS)

    Chakraborty, A.; Das, H. S.

    2016-09-01

    We trace the peripheral magnetic field structure of Bok globule CB130 by estimating the linear polarization of its field stars in the R band. The magnetic field orientation sampled by these stars, aligned on average among themselves, and the polarization produced within the cloud has a different direction from that of Galactic plane with an offset of 53°. The offset between minor axis and the mean magnetic field of CB130 is found to be 80°. The estimated strength of the magnetic field in the plane-of-the-sky is ˜116±19 μG. We constructed the visual extinction map using the Near Infrared Color Excess (NICE) method to see the dust distribution around CB130. Contours of Herschel (Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA) SPIRE 500 μm dust continuum emission map of this cloud is over-plotted on the visual extinction map, which shows that the regions having higher optical extinction correspond to higher densities of dust. Three distinct high dust density cores (named as C1, C2, and C3) are identified in the extinction map. It is observed that the cores C1 and C3 are located close to two previously known cores CB130-1 and CB130-2, respectively. Estimates of visual extinction of some moderately obscured stars of CB130 are made utilizing near-infrared photometry. It is observed that there is a feeble dependence of polarization on extinction, and the polarization efficiency (defined as p/AV) of the dust grains decreases with the increase in extinction.

  5. Shocked and Scorched: Free-Floating Evaporating Gas Globules and Star Formation in Cygnus

    NASA Astrophysics Data System (ADS)

    Sahai, Raghvendra; Claussen, M. J.; Morris, M. R.

    2012-05-01

    We report molecular line observations of a new class of Free-floating Evaporating Gas Globules with tadpole shapes (i.e., FrEGGs), recently discovered in the Cygnus star-forming region. We serendipitously found two of these in an HST imaging survey, including one of the most prominent members of this class (IRAS20324+4057: the Tadpole). Our molecular-line observations, carried out with the Arizona Radio Observatory's mm-wave telescopes, include on-the-fly maps in the CO and 13CO J=2-1 lines as well as pointed observations in the J=3-2 line of the high-density tracers HCO+ and N2H+. These data show the presence of dense molecular cores with total masses of cold molecular gas exceeding one to a few Msun in almost all FrEGGs. Our radio continuum imaging of 3 FrEGGs, as well as Halpha images from the IPHAS survey reveal bright photo-ionized peripheries around these objects. We infer that FrEGGs are dense, star-forming molecular cores that originated in the Cygnus cloud and are now being photoevaporated by the ultraviolet radiation field of the Cyg OB2 cluster, and shaped by the ram pressure of strong wind sources. The extended tails in some of the largest objects show wiggles likely resulting from Kelvin-Helmoltz instabilities. We find evidence for non-thermal radio emission in the Tadpole, with the radio emission peaking strongly along the shock/ionization front at its head, possibly as a result of a compressed magnetic layer in this front that is interacting with cosmic rays associated with the Cyg OB2 association.

  6. Supported Molten Metal Membranes for Hydrogen Separation

    SciTech Connect

    Datta, Ravindra; Ma, Yi Hua; Yen, Pei-Shan; Deveau, Nicholas; Fishtik, Ilie; Mardilovich, Ivan

    2013-09-30

    We describe here our results on the feasibility of a novel dense metal membrane for hydrogen separation: Supported Molten Metal Membrane, or SMMM.1 The goal in this work was to develop these new membranes based on supporting thin films of low-melting, non- precious group metals, e.g., tin (Sn), indium (In), gallium (Ga), or their alloys, to provide a flux and selectivity of hydrogen that rivals the conventional but substantially more expensive palladium (Pd) or Pd alloy membranes, which are susceptible to poisoning by the many species in the coal-derived syngas, and further possess inadequate stability and limited operating temperature range. The novelty of the technology presented numerous challenges during the course of this project, however, mainly in the selection of appropriate supports, and in the fabrication of a stable membrane. While the wetting instability of the SMMM remains an issue, we did develop an adequate understanding of the interaction between molten metal films with porous supports that we were able to find appropriate supports. Thus, our preliminary results indicate that the Ga/SiC SMMM at 550 ºC has a permeance that is an order of magnitude higher than that of Pd, and exceeds the 2015 DOE target. To make practical SMM membranes, however, further improving the stability of the molten metal membrane is the next goal. For this, it is important to better understand the change in molten metal surface tension and contact angle as a function of temperature and gas-phase composition. A thermodynamic theory was, thus, developed, that is not only able to explain this change in the liquid-gas surface tension, but also the change in the solid-liquid surface tension as well as the contact angle. This fundamental understanding has allowed us to determine design characteristics to maintain stability in the face of changing gas composition. These designs are being developed. For further progress, it is also important to understand the nature of solution and

  7. Delivery system for molten salt oxidation of solid waste

    DOEpatents

    Brummond, William A.; Squire, Dwight V.; Robinson, Jeffrey A.; House, Palmer A.

    2002-01-01

    The present invention is a delivery system for safety injecting solid waste particles, including mixed wastes, into a molten salt bath for destruction by the process of molten salt oxidation. The delivery system includes a feeder system and an injector that allow the solid waste stream to be accurately metered, evenly dispersed in the oxidant gas, and maintained at a temperature below incineration temperature while entering the molten salt reactor.

  8. Low temperature oxidation using support molten salt catalysts

    DOEpatents

    Weimer, Alan W.; Czerpak, Peter J.; Hilbert, Patrick M.

    2003-05-20

    Molten salt reactions are performed by supporting the molten salt on a particulate support and forming a fluidized bed of the supported salt particles. The method is particularly suitable for combusting hydrocarbon fuels at reduced temperatures, so that the formation NO.sub.x species is reduced. When certain preferred salts are used, such as alkali metal carbonates, sulfur and halide species can be captured by the molten salt, thereby reducing SO.sub.x and HCl emissions.

  9. Electrochemical cell utilizing molten alkali metal electrode-reactant

    DOEpatents

    Virkar, Anil V.; Miller, Gerald R.

    1983-11-04

    An improved electrochemical cell comprising an additive-modified molten alkali metal electrode-reactant and/or electrolyte is disclosed. Various electrochemical cells employing a molten alkali metal, e.g., sodium, electrode in contact with a cationically conductive ceramic membrane experience a lower resistance and a lower temperature coefficient of resistance whenever small amounts of selenium are present at the interface of the electrolyte and the molten alkali metal. Further, cells having small amounts of selenium present at the electrolyte-molten metal interface exhibit less degradation of the electrolyte under long term cycling conditions.

  10. Fluoride coatings make effective lubricants in molten sodium environment

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Coating bearing surfaces with calcium fluoride-barium fluoride film provides effective lubrication against sliding friction in molten sodium and other severe environments at high and low temperatures.

  11. Compatibility of molten salts with advanced solar dynamic receiver materials

    NASA Technical Reports Server (NTRS)

    Jaworske, D. A.; Perry, W. D.

    1989-01-01

    Metal-coated graphite fibers are being considered as a thermal conductivity enhancement filler material for molten salts in solar dynamic thermal energy storage systems. The successful metal coating chosen for this application must exhibit acceptable wettability and must be compatible with the molten salt environment. Contact angle values between molten lithium fluoride and several metal, metal fluoride, and metal oxide substrates have been determined at 892 C using a modification of the Wilhelmy plate technique. Reproducible contact angles with repeated exposure to the molten LiF indicated compatibility.

  12. Molten salt bath circulation design for an electrolytic cell

    DOEpatents

    Dawless, R.K.; LaCamera, A.F.; Troup, R.L.; Ray, S.P.; Hosler, R.B.

    1999-08-17

    An electrolytic cell for reduction of a metal oxide to a metal and oxygen has an inert anode and an upwardly angled roof covering the inert mode. The angled roof diverts oxygen bubbles into an upcomer channel, thereby agitating a molten salt bath in the upcomer channel and improving dissolution of a metal oxide in the molten salt bath. The molten salt bath has a lower velocity adjacent the inert anode in order to minimize corrosion by substances in the bath. A particularly preferred cell produces aluminum by electrolysis of alumina in a molten salt bath containing aluminum fluoride and sodium fluoride. 4 figs.

  13. Molten salt bath circulation design for an electrolytic cell

    DOEpatents

    Dawless, Robert K.; LaCamera, Alfred F.; Troup, R. Lee; Ray, Siba P.; Hosler, Robert B.

    1999-01-01

    An electrolytic cell for reduction of a metal oxide to a metal and oxygen has an inert anode and an upwardly angled roof covering the inert mode. The angled roof diverts oxygen bubbles into an upcomer channel, thereby agitating a molten salt bath in the upcomer channel and improving dissolution of a metal oxide in the molten salt bath. The molten salt bath has a lower velocity adjacent the inert anode in order to minimize corrosion by substances in the bath. A particularly preferred cell produces aluminum by electrolysis of alumina in a molten salt bath containing aluminum fluoride and sodium fluoride.

  14. Crust formation and its effect on the molten pool coolability

    SciTech Connect

    Park, R.J.; Lee, S.J.; Sim, S.K.

    1995-09-01

    Experimental and analytical studies of the crust formation and its effect on the molten pool coolability have been performed to examine the crust formation process as a function of boundary temperatures as well as to investigate heat transfer characteristics between molten pool and overlying water in order to evaluate coolability of the molten pool. The experimental test results have shown that the surface temperature of the bottom plate is a dominant parameter in the crust formation process of the molten pool. It is also found that the crust thickness of the case with direct coolant injection into the molten pool is greater than that of the case with a heat exchanger. Increasing mass flow rate of direct coolant injection to the molten pool does not affect the temperature of molten pool after the crust has been formed in the molten pool because the crust behaves as a thermal barrier. The Nusselt number between the molten pool and the coolant of the case with no crust formation is greater than that of the case with crust formation. The results of FLOW-3D analyses have shown that the temperature distribution contributes to the crust formation process due to Rayleigh-Benard natural convection flow.

  15. Carbonate- and silicate-rich globules in the kimberlitic rocks of northwestern Tarim large igneous province, NW China: Evidence for carbonated mantle source

    NASA Astrophysics Data System (ADS)

    Cheng, Zhiguo; Zhang, Zhaochong; Santosh, M.; Hou, Tong; Zhang, Dongyang

    2014-12-01

    We report carbonate- and silicate-rich globules and andradite from the Wajilitage kimberlitic rocks in the northwestern Tarim large igneous province, NW China. The carbonate-rich globules vary in size from 1 to 3 mm, and most have ellipsoidal or round shape, and are composed of nearly pure calcite. The silicate-rich globules are elliptical to round in shape and are typically larger than the carbonate-rich globules ranging from 2 to several centimeters in diameter. They are characterized by clear reaction rims and contain several silicate minerals such as garnet, diopside and phlogopite. The silicate-rich globules, reported here for the first time, are suggested to be related to the origin of andradite within the kimberlitic rocks. Our results show that calcite in the carbonate-rich globules has a high XCa (>0.97) and is characterized by extremely high concentrations of the total rare earth elements (up to 1500 ppm), enrichment in Sr (8521-10,645 ppm) and LREE, and remarkable depletion in Nd, Ta, Zr, Hf and Ti. The calcite in the silicate-rich globules is geochemically similar to those in the carbonate-rich globules except the lower trace element contents. Garnet is dominantly andradite (And59.56-92.32Grs5.67-36.03Pyr0.36-4.61Spe0-0.33) and is enriched in light rare earth elements (LREEs) and relatively depleted in Rb, Ba, Th, Pb, Sr, Zr and Hf. Phlogopite in the silicate-rich globules has a high Mg# ranging from 0.93 to 0.97. The composition of the diopside is Wo45.82-51.39En39.81-49.09Fs0.88-0.95 with a high Mg# ranging from 0.88 to 0.95. Diopside in the silicate-rich globules has low total rare earth element (REE) contents (14-31 ppm) and shows middle REE- (Eu to Gd), slight light REE- and heavy REE-enrichment with elevated Zr, Hf and Sr contents and a negative Nb anomaly in the normalized diagram. The matrix of the kimberlitic rocks are silica undersaturated (27.92-29.31 wt.% SiO2) with low Al2O3 (4.51-5.15 wt.%) and high CaO (17.29-17.77 wt.%) contents. The

  16. Secretion of three enzymes for fatty acid synthesis into mouse milk in association with fat globules, and rapid decrease of the secreted enzymes by treatment with rapamycin.

    PubMed

    Moriya, Hitomi; Uchida, Kana; Okajima, Tetsuya; Matsuda, Tsukasa; Nadano, Daita

    2011-04-01

    The mammary epithelium produces numerous lipid droplets during lactation and secretes them in plasma membrane-enclosed vesicles known as milk fat globules. The biogenesis of such fat globules is considered to provide a model for clarifying the mechanisms of lipogenesis in mammals. In the present study, we identified acetyl coenzyme A carboxylase, ATP citrate lyase, and fatty acid synthase in mouse milk. Fractionation of milk showed that these three enzymes were located predominantly in milk fat globules. The three enzymes were resistant to trypsin digestion without Triton X-100, indicating that they were not located on the outer surface of the globules and thus associated with the precursors of the globules before secretion. When a low dose of rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), was injected into lactating mice, the levels of the three enzymes in milk were decreased within 3h after injection. Since the protein levels of the three enzymes in tissues were not obviously altered by this short-term treatment, known transcriptional control by mTOR signaling was unlikely to account for this decrease in their levels in milk. Our findings suggest a new, putatively mTOR-dependent localization of the three enzymes for de novo lipogenesis. PMID:21281598

  17. Molten nitrate salt technology development status report

    SciTech Connect

    Carling, R.W.; Kramer, C.M.; Bradshaw, R.W.; Nissen, D.A.; Goods, S.H.; Mar, R.W.; Munford, J.W.; Karnowsky, M.M.; Biefeld, R.N.; Norem, N.J.

    1981-03-01

    Recognizing thermal energy storage as potentially critical to the successful commercialization of solar thermal power systems, the Department of Energy (DOE) has established a comprehensive and aggressive thermal energy storage technology development program. Of the fluids proposed for heat transfer and energy storage molten nitrate salts offer significant economic advantages. The nitrate salt of most interest is a binary mixture of NaNO/sub 3/ and KNO/sub 3/. Although nitrate/nitrite mixtures have been used for decades as heat transfer and heat treatment fluids the use has been at temperatures of about 450/sup 0/C and lower. In solar thermal power systems the salts will experience a temperature range of 350 to 600/sup 0/C. Because central receiver applications place more rigorous demands and higher temperatures on nitrate salts a comprehensive experimental program has been developed to examine what effects, if any, the new demands and temperatures have on the salts. The experiments include corrosion testing, environmental cracking of containment materials, and determinations of physical properties and decomposition mechanisms. This report details the work done at Sandia National Laboratories in each area listed. In addition, summaries of the experimental programs at Oak Ridge National Laboratory, the University of New York, EIC Laboratories, Inc., and the Norwegian Institute of Technology on molten nitrate salts are given. Also discussed is how the experimental programs will influence the near-term central receiver programs such as utility repowering/industrial retrofit and cogeneration. The report is designed to provide easy access to the latest information and data on molten NaNO/sub 3//KNO/sub 3/ for the designers and engineers of future central receiver projects.

  18. Electrically conductive containment vessel for molten aluminum

    DOEpatents

    Holcombe, C.E.; Scott, D.G.

    1984-06-25

    The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal 10 borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

  19. Electrically conductive containment vessel for molten aluminum

    DOEpatents

    Holcombe, Cressie E.; Scott, Donald G.

    1985-01-01

    The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

  20. Apparatus for controlling molten core debris

    DOEpatents

    Golden, Martin P. [Trafford, PA; Tilbrook, Roger W. [Monroeville, PA; Heylmun, Neal F. [Pittsburgh, PA

    1977-07-19

    Apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed.

  1. Apparatus for controlling molten core debris. [LMFBR

    DOEpatents

    Golden, M.P.; Tilbrook, R.W.; Heylmun, N.F.

    1977-07-19

    Disclosed is an apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed. 9 claims, 22 figures.

  2. Anode composite for molten carbonate fuel cell

    DOEpatents

    Iacovangelo, Charles D.; Zarnoch, Kenneth P.

    1983-01-01

    An anode composite useful for a molten carbonate fuel cell comprised of a porous sintered metallic anode component having a porous bubble pressure barrier integrally sintered to one face thereof, said barrier being comprised of metal coated ceramic particles sintered together and to said anode by means of said metal coating, said metal coating enveloping said ceramic particle and being selected from the group consisting of nickel, copper and alloys thereof, the median pore size of the barrier being significantly smaller than that of the anode.

  3. Safe actinide disposition in molten salt reactors

    SciTech Connect

    Gat, U.

    1997-03-01

    Safe molten salt reactors (MSR) can readily accommodate the burning of all fissile actinides. Only minor compromises associated with plutonium are required. The MSRs can dispose safely of actinides and long lived isotopes to result in safer and simpler waste. Disposing of actinides in MSRs does increase the source term of a safety optimized MSR. It is concluded that the burning and transmutation of actinides in MSRs can be done in a safe manner. Development is needed for the processing to handle and separate the actinides. Calculations are needed to establish the neutron economy and the fuel management. 9 refs.

  4. Thermal-hydraulics of internally heated molten salts and application to the Molten Salt Fast Reactor

    NASA Astrophysics Data System (ADS)

    Fiorina, Carlo; Cammi, Antonio; Luzzi, Lelio; Mikityuk, Konstantin; Ninokata, Hisashi; Ricotti, Marco E.

    2014-04-01

    The Molten Salt Reactors (MSR) are an innovative kind of nuclear reactors and are presently considered in the framework of the Generation IV International Forum (GIF-IV) for their promising performances in terms of low resource utilization, waste minimization and enhanced safety. A unique feature of MSRs is that molten fluoride salts play the distinctive role of both fuel (heat source) and coolant. The presence of an internal heat generation perturbs the temperature field and consequences are to be expected on the heat transfer characteristics of the molten salts. In this paper, the problem of heat transfer for internally heated fluids in a straight circular channel is first faced on a theoretical ground. The effect of internal heat generation is demonstrated to be described by a corrective factor applied to traditional correlations for the Nusselt number. It is shown that the corrective factor can be fully characterized by making explicit the dependency on Reynolds and Prandtl numbers. On this basis, a preliminary correlation is proposed for the case of molten fluoride salts by interpolating the results provided by an analytic approach previously developed at the Politecnico di Milano. The experimental facility and the related measuring procedure for testing the proposed correlation are then presented. Finally, the developed correlation is used to carry out a parametric investigation on the effect of internal heat generation on the main out-of-core components of the Molten Salt Fast Reactor (MSFR), the reference circulating-fuel MSR design in the GIF-IV. The volumetric power determines higher temperatures at the channel wall, but the effect is significant only in case of large diameters and/or low velocities.

  5. Production of Oxygen from Lunar Regolith using Molten Oxide Electrolysis

    NASA Technical Reports Server (NTRS)

    Sibille, Laurent; Sadoway, Donald R.; Sirk, Aislinn; Tripathy, Prabhat; Melendez, Orlando; Standish, Evan; Dominquez, Jesus A.; Stefanescu, Doru M.; Curreri, Peter A.; Poizeau, Sophie

    2009-01-01

    This slide presentation reviews the possible use of molten oxide electrolysis to extract oxygen from the Lunar Regolith. The presentation asserts that molten regolith electrolysis has advanced to be a useful method for production of oxygen and metals in situ on the Moon. The work has demonstrated an 8 hour batch of electrolysis at 5 amps using Iridium inert anodes.

  6. Method of making molten carbonate fuel cell ceramic matrix tape

    DOEpatents

    Maricle, Donald L.; Putnam, Gary C.; Stewart, Jr., Robert C.

    1984-10-23

    A method of making a thin, flexible, pliable matrix material for a molten carbonate fuel cell is described. The method comprises admixing particles inert in the molten carbonate environment with an organic polymer binder and ceramic particle. The composition is applied to a mold surface and dried, and the formed compliant matrix material removed.

  7. Pitting corrosion of aluminized seals in molten carbonate fuel cells

    SciTech Connect

    Krumpelt, M.; Roche, M.F.; Bloom, I.

    1994-08-01

    The objective of this research is to gain a better understanding of the corrosion of the aluminized type 316 stainless steel employed in the seal areas of the molten carbonate fuel cell. The seals are formed between the aluminized Type 316 SS surface and the electrolyte (generally a mixture of molten alkali carbonates and lithium aluminate).

  8. Pendant-Drop Surface-Tension Measurement On Molten Metal

    NASA Technical Reports Server (NTRS)

    Man, Kin Fung; Thiessen, David

    1996-01-01

    Method of measuring surface tension of molten metal based on pendant-drop method implemented in quasi-containerless manner and augmented with digital processing of image data. Electrons bombard lower end of sample rod in vacuum, generating hanging drop of molten metal. Surface tension of drop computed from its shape. Technique minimizes effects of contamination.

  9. 46 CFR 151.50-55 - Sulfur (molten).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Sulfur (molten). 151.50-55 Section 151.50-55 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-55 Sulfur (molten). (a... depositing of sulfur within the system. (b) Void spaces: (1) Openings to void spaces adjacent to cargo...

  10. 46 CFR 151.50-55 - Sulfur (molten).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Sulfur (molten). 151.50-55 Section 151.50-55 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-55 Sulfur (molten). (a... depositing of sulfur within the system. (b) Void spaces: (1) Openings to void spaces adjacent to cargo...

  11. 46 CFR 151.50-55 - Sulfur (molten).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Sulfur (molten). 151.50-55 Section 151.50-55 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-55 Sulfur (molten). (a... depositing of sulfur within the system. (b) Void spaces: (1) Openings to void spaces adjacent to cargo...

  12. 46 CFR 151.50-55 - Sulfur (molten).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Sulfur (molten). 151.50-55 Section 151.50-55 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-55 Sulfur (molten). (a... depositing of sulfur within the system. (b) Void spaces: (1) Openings to void spaces adjacent to cargo...

  13. Autoxidation and cytotoxicity

    SciTech Connect

    Borg, D C; Schaich, K M; Elmore, Jr, J J

    1980-01-01

    A comprehensive synthesis, or reaction schema, to relate autoxidations of non-lipid compounds to lipid chain peroxidation in vivo is presented. This is done in the context of cytotoxic autoxidation reactions, and it is concluded that hydroxyl radicals produced by iron-dependent Fenton reactions serve as both primary toxicants and as sources of secondary toxicants. The latter stem from lipid chain peroxidation initiated by the Fenton-derived hydroxyl radicals, which are visualized as the obligate coupling step linking enzyme-dependent and non-enzymic autoxidations to potentially toxic outcomes.

  14. A lattice model Monte Carlo study of coil-to-globule and other conformational transitions of polymer, amphiphile, and solvent

    NASA Astrophysics Data System (ADS)

    Jennings, Deirdre E.; Kuznetsov, Yuri A.; Timoshenko, Edward G.; Dawson, Kenneth A.

    2000-05-01

    A model of polymer-amphiphile-solvent systems on a cubic lattice is used to investigate the phase diagram of such systems. The polymer is treated within the canonical ensemble (T,V,N) and the amphiphile and solvent are treated within the grand canonical ensemble (T,V,μ). Using a range of Monte Carlo moves the phase diagram of polymer-amphiphile-solvent mixtures, as a function of solvent quality (parametrized by χ) and relative chemical potential, μ, is studied for the dilute polymer limit. The effect of increasing the polymer chain length, N, on the critical aggregation concentration (CAC), and the type of polymer-amphiphile complex formed above the CAC are also examined. For some parameters, it is found that the polymer and amphiphile form a polymer-micelle complex at low amphiphile concentrations, and that the polymer coil-to-globule transition point increases with increasing amphiphile concentration. The resulting collapsed globule has a solvent core and is surrounded by a layer of amphiphile. These results are in good qualitative agreement with experimental results for the poly(N-isopropylacrylamide) (PNIPAM)/sodium dodecyl sulfate (SDS) system. At higher amphiphile concentrations, the polymer and amphiphile form several layered structures depending on the strength of the three-body amphiphilic interactions, l. Finally, the effect of the polymer chain length, N, and the strength of the three-body amphiphilic interactions, l, on the stability of the polymer-amphiphile structures is investigated.

  15. Molten salt applications in materials processing

    NASA Astrophysics Data System (ADS)

    Mishra, Brajendra; Olson, David L.

    2005-02-01

    The science of molten salt electrochemistry for electrowinning of reactive metals, such as calcium, and its in situ application in pyro-reduction has been described. Calcium electrowinning has been performed in a 5 10 wt% calcium oxide calcium chloride molten salt by the electrolytic dissociation of calcium oxide. This electrolysis requires the use of a porous ceramic sheath around the anode to keep the cathodically deposited calcium and the anodic gases separate. Stainless steel cathode and graphite anode have been used in the temperature range of 850 950 °C. This salt mixture is produced as a result of the direct oxide reduction (DOR) of reactive metal oxides by calcium in a calcium chloride bath. The primary purpose of this process is to recover the expensive calcium reductant and to recycle calcium chloride. Experimental data have been included to justify the suitability as well as limitations of the electrowinning process. Transport of oxygen ions through the sheath is found to be the rate controlling step. Under the constraints of the reactor design, a calcium recovery rate of approx. 150 g/h was achieved. Feasibility of a process to produce metals by pyrometallurgical reduction, using the calcium reductant produced electrolytically within the same reactor, has been shown in a hybrid process. Several processes are currently under investigation to use this electrowon calcium for in situ reduction of metal oxides.

  16. Transient simulation of molten salt central receiver

    NASA Astrophysics Data System (ADS)

    Doupis, Dimitri; Wang, Chuan; Carcorze-Soto, Jorge; Chen, Yen-Ming; Maggi, Andrea; Losito, Matteo; Clark, Michael

    2016-05-01

    Alstom is developing concentrated solar power (CSP) utilizing 60/40wt% NaNO3-KNO3 molten salt as the working fluid in a tower receiver for the global renewable energy market. In the CSP power generation cycle, receivers undergo a daily cyclic operation due to the transient nature of solar energy. Development of robust and efficient start-up and shut-down procedures is critical to avoiding component failures due to mechanical fatigue resulting from thermal transients, thus maintaining the performance and availability of the CSP plant. The Molten Salt Central Receiver (MSCR) is subject to thermal transients during normal daily operation, a cycle that includes warmup, filling, operation, draining, and shutdown. This paper describes a study to leverage dynamic simulation and finite element analysis (FEA) in development of start-up, shutdown, and transient operation concepts for the MSCR. The results of the FEA also verify the robustness of the MSCR design to the thermal transients anticipated during the operation of the plant.

  17. Modeling of molten-fuel-moderator interactions

    NASA Astrophysics Data System (ADS)

    Diab, Aya K.

    CANDU reactors are pressurized heavy-water moderated and cooled reactor designs. During commissioning of nuclear power plants a range of possible accidents must be considered to assure the plants' robust design. Consider a complete channel blockage in the CANDU reactor. Such an extreme flow blockage event would result in fuel overheating, pressure tube failure, partial melting of fuel rods and possible molten fuel-moderator interactions (MFMI). The MFMI phenomenon would occur immediately after tube rupture, and would involve a mixture of steam, hydrogen and molten fuel being ejected into the surrounding moderator water in the form of a high-pressure vapor bubble mixture. This bubble mixture would accelerate the surrounding denser water, causing interfacial mixing due to hydrodynamic instabilities at the interface. As a result of these interfacial instabilities, water is entrained into the growing two-phase bubble mixture with the attendant mass and heat transfer; e.g., water vaporization, fuel oxidation. A comprehensive model is developed to investigate these complex phenomena resulting from a postulated complete flow blockage and complete pressure tube failure. This dynamic model serves as a baseline to characterize the pressure response due to a pressure tube rupture and the associated MFMI phenomena. Theoretical modeling of these interrelated complex phenomena is not known a priori and therefore a semi-empirical approach is adopted. Consequently, experimental work is being proposed as part of the thesis work to verify key hypotheses regarding these interfacial fluid instabilities, such as the entrainment fraction into the rapidly expanding bubble.

  18. Modeling Molten-Fuel-Moderator Interactions

    NASA Astrophysics Data System (ADS)

    Diab, Aya

    2005-11-01

    CANDU reactors are pressurized heavy-water moderated and cooled nuclear reactor designs. During commissioning of nuclear power plants a range of possible accidents must be considered to assure the plants' robust design. One must consider a complete channel blockage in the CANDU reactor. Such an extreme flow blockage event would result in fuel overheating, pressure tube failure, partial melting of fuel rods and possible molten fuel-moderator interactions (MFMI). The MFMI phenomenon would occur immediately following tube rupture, and involves a mixture of steam, hydrogen and molten fuel being ejected into the surrounding moderator water in the form of a high-pressure vapor bubble mixture. This bubble mixture would accelerate the surrounding denser water, causing interfacial mixing due to hydrodynamic instabilities at the interface. As a result of these interfacial instabilities, water is entrained into the growing two-phase bubble mixture with the attendant mass and heat transfer; e.g., water vaporization, fuel oxidation. A comprehensive model has been developed to investigate the complex phenomena resulting from a postulated complete flow blockage and pressure tube failure. This dynamic model will serve as a baseline to characterize the pressure response due to a pressure tube rupture and the associated MFMI phenomena.

  19. Organic waste processing using molten salt oxidation

    SciTech Connect

    Adamson, M. G., LLNL

    1998-03-01

    Molten Salt Oxidation (MSO) is a thermal means of oxidizing (destroying) the organic constituents of mixed wastes, hazardous wastes, and energetic materials while retaining inorganic and radioactive constituents in the salt. For this reason, MSO is considered a promising alternative to incineration for the treatment of a variety of organic wastes. The U. S. Department of Energy`s Office of Environmental Management (DOE/EM) is currently funding research that will identify alternatives to incineration for the treatment of organic-based mixed wastes. (Mixed wastes are defined as waste streams which have both hazardous and radioactive properties.) One such project is Lawrence Livermore National Laboratory`s Expedited Technology Demonstration of Molten Salt Oxidation (MSO). The goal of this project is to conduct an integrated demonstration of MSO, including off-gas and spent salt treatment, and the preparation of robust solid final forms. Livermore National Laboratory (LLNL) has constructed an integrated pilot-scale MSO treatment system in which tests and demonstrations are presently being performed under carefully controlled (experimental) conditions. The system consists of a MSO process vessel with dedicated off-gas treatment, a salt recycle system, feed preparation equipment, and equipment for preparing ceramic final waste forms. In this paper we describe the integrated system and discuss its capabilities as well as preliminary process demonstration data. A primary purpose of these demonstrations is to identify the most suitable waste streams and waste types for MSO treatment.

  20. Pump for molten metal or other fluid

    DOEpatents

    Horton, James A.; Brown, Donald L.

    1994-01-01

    A pump having no moving parts which can be used to pump high temperature molten metal or other fluids in a vacuum or low pressure environment, and a method for pumping such fluids. The pump combines elements of a bubble pump with a trap which isolates the vacuum or low pressure region from the gas used to create the bubbles. When used in a vacuum the trap prevents the pumping gas from escaping into the isolated region and thereby reducing the quality of the vacuum. The pump includes a channel in which a pumping gas is forced under pressure into a cavity where bubbles are formed. The cavity is in contact with a reservoir which contains the molten metal or other fluid which is to be pumped. The bubbles rise up into a column (or pump tube) carrying the fluid with them. At the top of the column is located a deflector which causes the bubbles to burst and the drops of pumped fluid to fall into a trap. The fluid accumulates in the trap, eventually forcing its way to an outlet. A roughing pump can be used to withdraw the pumping gas from the top of the column and assist with maintaining the vacuum or low pressure environment.

  1. Alternative cathodes for molten carbonate fuel cells

    SciTech Connect

    Bloom, I.; Lanagan, M.; Roche, M.F.; Krumpelt, M.

    1996-02-01

    Argonne National Laboratory (ANL) is developing advanced cathodes for pressurized operation of the molten carbonate fuel cell (MCFC). The present cathode, lithiated nickel oxide, tends to transport to the anode of the MCFC, where it is deposited as metallic nickel. The rate of transport increases with increasing CO{sub 2} pressure. This increase is due to an increased solubility of nickel oxide (NiO) in the molten carbonate electrolyte. An alternative cathode is lithium cobaltate (LiCoO{sub 2})-Solid solutions of LiCoO{sub 2} in LiFeO{sub 2} show promise for long-lived cathode materials. We have found that small additions of LiCoO{sub 2} to LiFeO{sub 2} markedly decrease the resistivity of the cathode material. Cells containing the LiCoO{sub 2}-LiFeO{sub 2} cathodes have stable performance for more than 2100 h of operation and display lower cobalt migration.

  2. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    SciTech Connect

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  3. Cytotoxicity of denture adhesives.

    PubMed

    de Gomes, Pedro Sousa; Figueiral, Maria Helena; Fernandes, Maria Helena R; Scully, Crispian

    2011-12-01

    Ten commercially available denture adhesives, nine soluble formulations (six creams, three powders) and one insoluble product (pad), were analyzed regarding the cytotoxicity profile in direct and indirect assays using L929 fibroblast cells. In the direct assay, fibroblasts were seeded over the surface of a thick adhesive gel (5%, creams; 2.5%, powders and pad). In the indirect assay, cells were cultured in the presence of adhesive extracts prepared in static and dynamic conditions (0.5-2%, creams; 0.25-1%, powders and pad). Cell toxicity was assessed for cell viability/proliferation (MTT assay) and cell morphology (observation of the F-actin cytoskeleton organization by confocal laser scanning microscopy). Direct contact of the L929 fibroblasts with the thick adhesive gels caused no, or only a slight, decrease in cell viability/proliferation. The adhesive extracts (especially those prepared in dynamic conditions) caused significantly higher growth inhibition of fibroblasts and, in addition, caused dose- and time-dependent effects, throughout the 6-72 h exposure time. Also, dose-dependent effects on cell morphology, with evident disruption of the F-actin cytoskeleton organization, were seen in the presence of most adhesives. In conclusion, the adhesives possessed different degrees of cytotoxicity, but similar dose- and time-dependent biological profiles.

  4. Impact, thermal, and shock sensitivity of molten TNT and of asphalt-contaminated molten TNT

    SciTech Connect

    Mainiero, R.J.; Miron, Y.; Kwak, S.S.W.; Kopera, L.H.; Wheeler, J.Q.

    1996-12-01

    The research reported here was part of an effort to evaluate the safety of a process to recover TNT from MK-9 depth bombs by the autoclave meltout process. In this process the depth bombs are heated to 121 C so that the TNT will melt and run into a vat. Unfortunately, asphalt lining the inside surface of the bomb also melts and flows out with the TNT. Testing was conducted on molten TNT and molten TNT contaminated with 2 pct asphalt at 90, 100, 110, 120, 125, and 130 C. In the liquid drop test apparatus with a 2-kg weight, the molten TNT yielded a 50 pct probability of initiation at a drop height of 6.5 cm at 110 C, decreasing to 4.5 cm at 130 C. Asphalt-contaminated TNT was somewhat less impact-sensitive than pure TNT at temperatures of 110 to 125 C, but became more sensitive at 130 C. There is a 50 pct probability of initiation at a drop height of 7.8 cm at 110 C, decreasing to 3.3 cm at 130 C. In the card gap test, the molten TNT detonated at high velocity for a gap of 0.25 inches at 90 to 125 C and detonated at high velocity for a gap of 0.5 inches at 130 C. For gaps of 0.5 to 3 inches at 90 to 125 C and 0.75 inches to 3 inches at 130 C, the TNT did not detonate at high velocity but produced a violent explosion that caused significant damage to the test fixture. The thermal analysis test results showed that when asphalt is present in TNT, it greatly accelerates the exothermic decomposition of TNT, starting at temperatures near 200 C. It appears that at relatively low shock stimulus levels, the molten TNT may be undergoing a low velocity detonation, wherein the shock wave traveling through the gap test pipe cavitates the molten TNT, greatly increasing its sensitivity. These results are crucial for assuring continued safety in recovering TNT from munitions through the autoclave meltout process.

  5. Casting Apparatus Including A Gas Driven Molten Metal Injector And Method

    DOEpatents

    Trudel, David R.; Meyer, Thomas N.; Kinosz, Michael J.; Arnaud, Guy; Bigler, Nicolas

    2003-06-17

    The filtering molten metal injector system includes a holder furnace, a casting mold supported above the holder furnace, and at least one molten metal injector supported from a bottom side of the casting mold. The holder furnace contains a supply of molten metal. The mold defines a mold cavity for receiving the molten metal from the holder furnace. The molten metal injector projects into the holder furnace. The molten metal injector includes a cylinder defining a piston cavity housing a reciprocating piston for pumping the molten metal upward from the holder furnace to the mold cavity. The cylinder and piston are at least partially submerged in the molten metal when the holder furnace contains the molten metal. The cylinder or the piston includes a molten metal intake for receiving the molten metal into the piston cavity when the holder furnace contains molten metal. A conduit connects the piston cavity to the mold cavity. A molten metal filter is located in the conduit for filtering the molten metal passing through the conduit during the reciprocating movement of the piston. The molten metal intake may be a valve connected to the cylinder, a gap formed between the piston and an open end of the cylinder, an aperture defined in the sidewall of the cylinder, or a ball check valve incorporated into the piston. A second molten metal filter preferably covers the molten metal intake to the injector.

  6. Grain boundary wetness of partially molten dunite

    NASA Astrophysics Data System (ADS)

    Mu, S.; Faul, U.

    2013-12-01

    The grain scale melt distribution plays a key role for physical properties of partially molten regions in Earth's upper mantle, but our current understanding of the distribution of basaltic melt at the grain scale is still incomplete. A recent experimental study shows that wetted two-grain boundaries are a common feature of partially molten dunite at small melt fractions (Garapic et al., G3, 2013). In early ideal models which assume isotropic surface energy, the grain scale melt distribution is uniquely determined by knowing the melt fraction and the dihedral angle between two crystalline grains and the melt (von Bargen and Waff, JGR, 1986). Olivine is anisotropic in surface energy, hence the grain scale melt distribution at given melt fraction cannot be characterized by the dihedral angle alone. The grain boundary wetness, which is defined as the ratio of solid-liquid boundary area over the total interfacial area (Takei, JGR, 1998), is a more objective measure of the grain scale melt distribution. The aim of this study is to quantify the relationship between grain size, melt fraction, temperature and grain boundary wetness of partially molten dunite under dry conditions. We annealed olivine-basalt aggregates with melt fractions from 0.03% to 6% at a range of temperatures and 1 GPa in a piston cylinder for 1 to 336 hours, with resulting mean grain sizes of 10 to 60 μm. The samples were sectioned, polished and imaged at high resolution by using a field emission SEM. Each image had a size of 2048 x 1536 pixels with a resolution of 0.014 to 0.029 μm/pixel, depending on magnification. For each sample, depending on grain sizes, we made mosaics of 3 x 3 or 6 x 6 overlapping images. Measurements of melt fraction, grain boundary wetness and grain size were carried out on these high resolution mosaics by using ImageJ software. Analyses of mosaics show that grain boundary wetness increases with increasing melt fraction at constant grain size to values well above those

  7. Reaction Infiltration Instabilities in Partially Molten Rocks

    NASA Astrophysics Data System (ADS)

    Pec, M.; Holtzman, B. K.; Zimmerman, M. E.; Kohlstedt, D. L.

    2015-12-01

    Tabular dunites in ophiolites are thought to form high-permeability, melt channels due to a positive feedback between melt flow and melt-solid reaction in the upper mantle. Reaction-infiltration instability (RII) theory predicts whether or not channels emerge from background flow. To test the applicability of RII theory to mantle rocks, we sandwiched a partially molten rock between a melt reservoir and a porous sink. Hot-pressed 50:50 mixtures of olivine (Ol) and clinopyroxene (Cpx) with either 4, 10 or 20 vol% alkali basalt formed ~4 mm long cylinders of partially molten rock. Source and sink are disks of alkali basalt and porous alumina. We annealed the melt-rock-sink triplets for up to 5 h at a confining pressure of Pc=300 MPa with effective pressure Pe=0 to 299.9 MPa at T=1200° or 1250°C. The melt fraction in the partially molten rock influences the permeability, which, together with the applied pressure gradient, controls the melt migration velocity. The temperature influences the reaction rate. Melt velocity and reaction rate are fundamental parameters in RII theory. In experiments, two distinct features form due to melt migration, 1) a planar reaction layer (RL) and 2) finger-shaped channels. Both the RL and the channels contain Ol+melt with no Cpx, indicating that the reaction melt1+Cpx→melt2+Ol occurs. The channels develop only if the melt velocity is >5µm/s. Once a channel reaches the porous sink, a large increase in the effective permeability is detected. The morphology and spacing of the channels depends on the initial melt fraction. With 20 vol% melt, multiple, voluminous channels with a spacing of 1.8±0.5 mm develop. At lower melt contents, fewer, thinner channels with a spacing of ~3 mm develop. The channel spacing predicted by theory is about a factor 2-4 smaller than observed. Our results indicate that RII theory provides a solid framework for investigating melt migration in experiments and potentially a basis for extrapolation to mantle

  8. Gold Nanoparticles Cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mironava, Tatsiana

    Over the last two decades gold nanoparticles (AuNPs) have been used for many scientific applications and have attracted attention due to the specific chemical, electronic and optical size dependent properties that make them very promising agents in many fields such as medicine, imagine techniques and electronics. More specifically, biocompatible gold nanoparticles have a huge potential for use as the contrast augmentation agent in X-ray Computed Tomography and Photo Acoustic Tomography for early tumor diagnostic as well these nanoparticles are extensively researched for enhancing the targeted cancer treatment effectiveness such as photo-thermal and radiotherapy. In most biomedical applications biocompatible gold nanoparticles are labeled with specific tumor or other pathology targeting antibodies and used for site specific drug delivery. However, even though gold nanoparticles poses very high level of anti cancer properties, the question of their cytotoxicity ones they are released in normal tissue has to be researched. Moreover, the huge amount of industrially produced gold nanoparticles raises the question of these particles being a health hazard, since the penetration is fairly easy for the "nano" size substances. This study focuses on the effect of AuNPs on a human skin tissue, since it is fall in both categories -- the side effects for biomedical applications and industrial workers and users' exposure during production and handling. Therefore, in the present project, gold nanoparticles stabilized with the biocompatible agent citric acid were generated and characterized by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The cytotoxic effect of AuNPs release to healthy skin tissue was modeled on 3 different cell types: human keratinocytes, human dermal fibroblasts, and human adipose derived stromal (ADS) cells. The AuNPs localization inside the cell was found to be cell type dependent. Overall cytotoxicity was found to be dependent

  9. Cytotoxicity of halogenated graphenes

    NASA Astrophysics Data System (ADS)

    Teo, Wei Zhe; Khim Chng, Elaine Lay; Sofer, Zdeněk; Pumera, Martin

    2013-12-01

    Graphene and its family of derivatives possess unique and remarkable physicochemical properties which make them valuable materials for applications in many areas like electronics, energy storage and biomedicine. In response to the possibility of its large-scale manufacturing as commercial products in the future, an investigation was conducted to determine the cytotoxicity of one particular family of graphene derivatives, the halogenated graphenes, for the first time. Halogenated graphenes were prepared through thermal exfoliation of graphite oxide in gaseous chlorine, bromine or iodine atmospheres to yield chlorine- (TRGO-Cl), bromine- (TRGO-Br) and iodine-doped graphene (TRGO-I) respectively. 24 h exposure of human lung carcinoma epithelial cells (A549) to the three halogenated graphenes and subsequent cell viability assessments using methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8) assays revealed that all the halogenated graphenes examined are rather cytotoxic at the concentrations tested (3.125 μg mL-1 to 200 μg mL-1) and the effects are dose-dependent, with TRGO-Cl reducing the cell viability to as low as 25.7% at the maximum concentration of 200 μg mL-1. Their levels of cytotoxicity can be arranged in the order of TRGO-Cl > TRGO-Br > TRGO-I, and it is suggested that the amount of halogen present in the graphene material is the determining factor for the observed trend. Control experiments were carried out to test for possible nanomaterial-induced interference as a consequence of reaction between the halogenated graphenes and the viability markers (MTT/WST-8 reagent) or binding of the formazan products under cell-free conditions. The data obtained eliminate the probability of significant influence by these interferents as the change in the normalized percentage of formazan formed is relatively small and thorough washings were performed prior to the viability assessments to reduce the amount of halogenated

  10. Cytotoxicity of halogenated graphenes.

    PubMed

    Teo, Wei Zhe; Chng, Elaine Lay Khim; Sofer, Zdeněk; Pumera, Martin

    2014-01-21

    Graphene and its family of derivatives possess unique and remarkable physicochemical properties which make them valuable materials for applications in many areas like electronics, energy storage and biomedicine. In response to the possibility of its large-scale manufacturing as commercial products in the future, an investigation was conducted to determine the cytotoxicity of one particular family of graphene derivatives, the halogenated graphenes, for the first time. Halogenated graphenes were prepared through thermal exfoliation of graphite oxide in gaseous chlorine, bromine or iodine atmospheres to yield chlorine- (TRGO-Cl), bromine- (TRGO-Br) and iodine-doped graphene (TRGO-I) respectively. 24 h exposure of human lung carcinoma epithelial cells (A549) to the three halogenated graphenes and subsequent cell viability assessments using methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8) assays revealed that all the halogenated graphenes examined are rather cytotoxic at the concentrations tested (3.125 μg mL(-1) to 200 μg mL(-1)) and the effects are dose-dependent, with TRGO-Cl reducing the cell viability to as low as 25.7% at the maximum concentration of 200 μg mL(-1). Their levels of cytotoxicity can be arranged in the order of TRGO-Cl > TRGO-Br > TRGO-I, and it is suggested that the amount of halogen present in the graphene material is the determining factor for the observed trend. Control experiments were carried out to test for possible nanomaterial-induced interference as a consequence of reaction between the halogenated graphenes and the viability markers (MTT/WST-8 reagent) or binding of the formazan products under cell-free conditions. The data obtained eliminate the probability of significant influence by these interferents as the change in the normalized percentage of formazan formed is relatively small and thorough washings were performed prior to the viability assessments to reduce the amount of halogenated

  11. Parametric study of natural circulation flow in molten salt fuel in molten salt reactor

    NASA Astrophysics Data System (ADS)

    Pauzi, Anas Muhamad; Cioncolini, Andrea; Iacovides, Hector

    2015-04-01

    The Molten Salt Reactor (MSR) is one of the most promising system proposed by Generation IV Forum (GIF) for future nuclear reactor systems. Advantages of the MSR are significantly larger compared to other reactor system, and is mainly achieved from its liquid nature of fuel and coolant. Further improvement to this system, which is a natural circulating molten fuel salt inside its tube in the reactor core is proposed, to achieve advantages of reducing and simplifying the MSR design proposed by GIF. Thermal hydraulic analysis on the proposed system was completed using a commercial computation fluid dynamics (CFD) software called FLUENT by ANSYS Inc. An understanding on theory behind this unique natural circulation flow inside the tube caused by fission heat generated in molten fuel salt and tube cooling was briefly introduced. Currently, no commercial CFD software could perfectly simulate natural circulation flow, hence, modeling this flow problem in FLUENT is introduced and analyzed to obtain best simulation results. Results obtained demonstrate the existence of periodical transient nature of flow problem, hence improvements in tube design is proposed based on the analysis on temperature and velocity profile. Results show that the proposed system could operate at up to 750MW core power, given that turbulence are enhanced throughout flow region, and precise molten fuel salt physical properties could be defined. At the request of the authors and the Proceedings Editor the name of the co-author Andrea Cioncolini was corrected from Andrea Coincolini. The same name correction was made in the Acknowledgement section on page 030004-10 and in reference number 4. The updated article was published on 11 May 2015.

  12. Parametric study of natural circulation flow in molten salt fuel in molten salt reactor

    SciTech Connect

    Pauzi, Anas Muhamad; Cioncolini, Andrea; Iacovides, Hector

    2015-04-29

    The Molten Salt Reactor (MSR) is one of the most promising system proposed by Generation IV Forum (GIF) for future nuclear reactor systems. Advantages of the MSR are significantly larger compared to other reactor system, and is mainly achieved from its liquid nature of fuel and coolant. Further improvement to this system, which is a natural circulating molten fuel salt inside its tube in the reactor core is proposed, to achieve advantages of reducing and simplifying the MSR design proposed by GIF. Thermal hydraulic analysis on the proposed system was completed using a commercial computation fluid dynamics (CFD) software called FLUENT by ANSYS Inc. An understanding on theory behind this unique natural circulation flow inside the tube caused by fission heat generated in molten fuel salt and tube cooling was briefly introduced. Currently, no commercial CFD software could perfectly simulate natural circulation flow, hence, modeling this flow problem in FLUENT is introduced and analyzed to obtain best simulation results. Results obtained demonstrate the existence of periodical transient nature of flow problem, hence improvements in tube design is proposed based on the analysis on temperature and velocity profile. Results show that the proposed system could operate at up to 750MW core power, given that turbulence are enhanced throughout flow region, and precise molten fuel salt physical properties could be defined. At the request of the authors and the Proceedings Editor the name of the co-author Andrea Cioncolini was corrected from Andrea Coincolini. The same name correction was made in the Acknowledgement section on page 030004-10 and in reference number 4. The updated article was published on 11 May 2015.

  13. Energetic materials destruction using molten salt

    SciTech Connect

    Upadhye, R.S.; Watkins, B.E.; Pruneda, C.O.; Brummond, W.A.

    1994-04-29

    The Lawrence Livermore National Laboratory in conjunction with the Energetic Materials Center is developing methods for the safe and environmentally sound destruction of explosives and propellants as a part of the Laboratory`s ancillary demilitarization mission. LLNL has built a small-scale unit to test the destruction of HE using the Molten Salt Destruction (MSD) Process. In addition to the high explosive HMX, destruction has been carried out on RDX, PETN, ammonium picrate, TNT, nitroguanadine, and TATB. Also destroyed was a liquid gun propellant comprising hydroxyammonium nitrate, triethanolammonium nitrate and water. In addition to these pure components, destruction has been carried out on a number of commonly used formulations, such as LX-10, LX-16, LX-17, and PBX-9404.

  14. Molten Composition B Viscosity at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Zerkle, David K.; Núñez, Marcel P.; Zucker, Jonathan M.

    2016-10-01

    A shear-thinning viscosity model is developed for molten Composition B at elevated temperature from analysis of falling ball viscometer data. Results are reported with the system held at 85, 110, and 135°C. Balls of densities of 2.7, 8.0, and 15.6 g/cm3 are dropped to generate a range of strain rates in the material. Analysis of video recordings gives the speed at which the balls fall. Computer simulation of the viscometer is used to determine parameters for a non-Newtonian model calibrated to measured speeds. For the first time, viscosity is shown to be a function of temperature and strain rate-dependent maximum RDX (cyclotrimethylenetrinitramine) particle volume fraction.

  15. The removal of iron from molten aluminium

    SciTech Connect

    Donk, H.M. van der; Nijhof, G.H.; Castelijns, C.A.M.

    1995-12-31

    In this work an overview is given about the techniques available for the removal of metallic impurities from molten aluminium. The overview is focused on the removal of iron. Also, some experimental results are given about the creation of iron-rich intermetallic compounds in an aluminium system, which are subsequently removed by gravity segregation and filtration techniques. This work is part of an ongoing research project of three major European aluminium companies who are co-operating on the subject of recycling of aluminium packaging materials recovered from household waste by means of Eddy-Current techniques. Using this technique the pick-up of some contaminating metals, particularly iron, is almost unavoidable.

  16. Molten salt eutectics from atomistic simulations.

    PubMed

    Jayaraman, Saivenkataraman; Thompson, Aidan P; von Lilienfeld, O Anatole

    2011-09-01

    Despite their importance for solar thermal power applications, phase-diagrams of molten salt mixture heat transfer fluids (HTFs) are not readily accessible from first principles. We present a molecular dynamics scheme general enough to identify eutectics of any HTF candidate mixture. The eutectic mixture and temperature are located using the liquid mixture free energy and the pure component solid-liquid free energy differences. The liquid mixture free energy is obtained using thermodynamic integration over particle identity transmutations sampled with molecular dynamics at a single temperature. Drawbacks of conventional phase diagram mapping methodologies are avoided by not considering solid mixtures, thereby evading expensive computations of solid phase free energies. Numerical results for binary and ternary mixtures of alkali nitrates agree well with experimental measurements.

  17. Modelisation of the SECMin molten salts environment

    NASA Astrophysics Data System (ADS)

    Lucas, M.; Slim, C.; Delpech, S.; di Caprio, D.; Stafiej, J.

    2014-06-01

    We develop a cellular automata modelisation of SECM experiments to study corrosion in molten salt media for generation IV nuclear reactors. The electrodes used in these experiments are cylindrical glass tips with a coaxial metal wire inside. As the result of simulations we obtain the current approach curves of the electrodes with geometries characterized by several values of the ratios of glass to metal area at the tip. We compare these results with predictions of the known analytic expressions, solutions of partial differential equations for flat uniform geometry of the substrate. We present the results for other, more complicated substrate surface geometries e. g. regular saw modulated surface, surface obtained by Eden model process, ...

  18. [Fission Working Group -- Molten salt reactors

    SciTech Connect

    Gat, U.; Engel, J.R.

    1992-01-01

    This report provides an assessment of molten salt reactors (MSRs) which are fluid fuel reactors and, as such, have several unique features, some which are important to the burning of fissile material from dismantled weapons. This material can be added on-line during operation in either continuous or batch form. The added fuel need only be in an acceptable chemical form, but no fuel manufacturing or minimum discrete amounts for a fuel element are required. Fluid fuel reactors can have partial or full on-line fuel processing. When online fuel processing is utilized, a particular fuel component, for example the plutonium, can be burned completely, or in some sense can be converted to other kinds of fuel, for example into [sup 233]U. There is no equivalent of fuel burnup in continuous processing reactors, and no need for reprocessing in external plants and manufacturing of fuel elements, transportation, and reinsertion in the reactor.

  19. [Fission Working Group -- Molten salt reactors

    SciTech Connect

    Gat, U.; Engel, J.R.

    1992-12-31

    This report provides an assessment of molten salt reactors (MSRs) which are fluid fuel reactors and, as such, have several unique features, some which are important to the burning of fissile material from dismantled weapons. This material can be added on-line during operation in either continuous or batch form. The added fuel need only be in an acceptable chemical form, but no fuel manufacturing or minimum discrete amounts for a fuel element are required. Fluid fuel reactors can have partial or full on-line fuel processing. When online fuel processing is utilized, a particular fuel component, for example the plutonium, can be burned completely, or in some sense can be converted to other kinds of fuel, for example into {sup 233}U. There is no equivalent of fuel burnup in continuous processing reactors, and no need for reprocessing in external plants and manufacturing of fuel elements, transportation, and reinsertion in the reactor.

  20. Single ion dynamics in molten sodium bromide

    SciTech Connect

    Alcaraz, O.; Trullas, J.; Demmel, F.

    2014-12-28

    We present a study on the single ion dynamics in the molten alkali halide NaBr. Quasielastic neutron scattering was employed to extract the self-diffusion coefficient of the sodium ions at three temperatures. Molecular dynamics simulations using rigid and polarizable ion models have been performed in parallel to extract the sodium and bromide single dynamics and ionic conductivities. Two methods have been employed to derive the ion diffusion, calculating the mean squared displacements and the velocity autocorrelation functions, as well as analysing the increase of the line widths of the self-dynamic structure factors. The sodium diffusion coefficients show a remarkable good agreement between experiment and simulation utilising the polarisable potential.

  1. Dynamics of vitreous and molten zinc chloride

    SciTech Connect

    Price, D.L.; Saboungi, M.L.; Susman, S.; Volin, K.J. ); Wright, A.C. . J.J. Thomson Physical Lab.)

    1991-09-01

    The dynamics of vitreous and molten zinc chloride have been studied with inelastic neutron scattering at the Intense Pulsed Neutron Source. The results are analyzed in terms of the scattering function S(Q,E) and the effective vibrational density of states G(E). The vibrational spectra of both glass and liquid are dominated by broad features centered at 15 and 35 MeV which are identified with F{sub 2} modes of ZnCl{sub 4}{sup 2{minus}} tetrahedra. The other two normal modes are not observed because of inadequate resolution and broadening and overlap resulting from coupling between tetrahedra. The behavior of ZnCl{sub 2} is contrasted with other tetrahedrally coordinated glasses that have been studied with the same technique. 15 refs,. 5 figs., 1 tab.

  2. Sulphide globules and their impact on sulphur degassing budget: the case of Grímsvötn volcano, Iceland.

    NASA Astrophysics Data System (ADS)

    Haddadi, Baptiste; Carn, Simon; Sigmarsson, Olgeir

    2014-05-01

    Volcanic eruptions are known to contribute sulphur to the atmosphere. Two different methods allow estimation of sulphur mass loading: remote satellite measurements and the petrologic method. Sulphur emission at subduction-related volcanoes is often underestimated by the latter method relative to the former whereas a fair agreement is found for hot spot-related volcanoes. The Grímsvötn 2011 eruption allows further comparison between these two methods. Grímsvötn is a basaltic subglacial volcano located under the Vatnajökull ice cap, above the Iceland mantle plume and the Mid-Atlantic Ridge. The May 2011 eruption lasted one week and took place inside the composite caldera of the volcano. During the first 24 hours, the column reached a height of more than 20 km and bulk of the magma was emitted. The basaltic tephra has quartz-normative tholeiite composition with 1-5% plagioclase, clinopyroxene, olivine, FeTi-oxide crystals and, noteworthy, sulphide globules present in the groundmass glass. Sulphur concentrations of twenty eight melt inclusions (MIs) were measured in plagioclase, clinopyroxene and olivine crystals extracted from the tephra produced during the most explosive phase. The difference between the mean sulphur content of both MIs and groundmass glass multiplied by the magma mass erupted, yields 0.73 ± 0.18 Tg of liberated sulphur. This is four times the estimated sulphur degassing by satellite measurements (0.19 ± 0.06 Tg). The contributions of different sulphur sinks were quantified. The geothermal system harvests approximately 0.037 Tg (5%), which are liberated during jökulhlaups. Sulphur adhering to the volcanic ash is approximately 0.12 Tg (15%). Added to the satellite measurements of sulphur entering the stratosphere, half of the S estimated by the petrologic method is still missing. Sulphur immiscibility forming sulphur globules in the magma chambers appears the most probable explanation for the missing 50% of sulphur. Due to elevated density of

  3. Grain boundary wetness of partially molten dunite

    NASA Astrophysics Data System (ADS)

    Mu, Shangshang; Faul, Ulrich H.

    2016-05-01

    Samples of Fo90 olivine and basaltic melt were annealed at a range of temperatures and a pressure of 1 GPa in a piston cylinder apparatus from 1 to 336 h. Post-run samples have melt contents from 0.3 to 6.8 % and mean grain sizes from 4.3 to 84.5 μm. Grain boundary wetness, a measure of the intergranular melt distribution, was determined by analyzing scanning electron microscope images with sufficiently high resolution to detect thin layers wetting grain boundaries, as well as small triple junctions. The measurements show that grain boundary wetness increases with increasing melt content to values well above those predicted by the idealized isotropic equilibrium model for a finite dihedral angle. Additionally, the melt geometry changes with grain size, with grain boundary wetness increasing with increasing grain size at fixed melt content. Grain boundary wetness and dihedral angle of samples annealed at a range of temperatures, but constant melt content does not depend on temperature. These observations emphasize that the dihedral angle alone is not adequate to characterize the melt distribution in partially molten rocks, as the idealized isotropic model does not account for the influence of grain growth. Diffusion creep viscosities calculated from the measured wetness reflect the grain size and melt content dependence. Accordingly, experimentally measured viscosities at small grain sizes underestimate the effect of melt to weaken partially molten rocks for coarser grain sizes. The presence of melt in the mantle may therefore enhance diffusion creep relative to dislocation creep.

  4. Fast Spectrum Molten Salt Reactor Options

    SciTech Connect

    Gehin, Jess C; Holcomb, David Eugene; Flanagan, George F; Patton, Bruce W; Howard, Rob L; Harrison, Thomas J

    2011-07-01

    During 2010, fast-spectrum molten-salt reactors (FS-MSRs) were selected as a transformational reactor concept for light-water reactor (LWR)-derived heavy actinide disposition by the Department of Energy-Nuclear Energy Advanced Reactor Concepts (ARC) program and were the subject of a preliminary scoping investigation. Much of the reactor description information presented in this report derives from the preliminary studies performed for the ARC project. This report, however, has a somewhat broader scope-providing a conceptual overview of the characteristics and design options for FS-MSRs. It does not present in-depth evaluation of any FS-MSR particular characteristic, but instead provides an overview of all of the major reactor system technologies and characteristics, including the technology developments since the end of major molten salt reactor (MSR) development efforts in the 1970s. This report first presents a historical overview of the FS-MSR technology and describes the innovative characteristics of an FS-MSR. Next, it provides an overview of possible reactor configurations. The following design features/options and performance considerations are described including: (1) reactor salt options-both chloride and fluoride salts; (2) the impact of changing the carrier salt and actinide concentration on conversion ratio; (3) the conversion ratio; (4) an overview of the fuel salt chemical processing; (5) potential power cycles and hydrogen production options; and (6) overview of the performance characteristics of FS-MSRs, including general comparative metrics with LWRs. The conceptual-level evaluation includes resource sustainability, proliferation resistance, economics, and safety. The report concludes with a description of the work necessary to begin more detailed evaluation of FS-MSRs as a realistic reactor and fuel cycle option.

  5. Production of Lunar Concrete Using Molten Sulfur

    NASA Technical Reports Server (NTRS)

    Omar, Husam A.

    1993-01-01

    The United States has made a commitment to go back to the moon to stay in the early part of the next century. In order to achieve this objective it became evident to NASA that a Lunar Outpost will be needed to house scientists and astronauts who will be living on the moon for extended periods of time. A study has been undertaken by the authors and supported by NASA to study the feasibility of using lunar regolith with different binders such as molten sulfur, epoxy or hydraulic cement as a construction material for different lunar structures. The basic premise of this study is that it will be more logical and cost effective to manufacture lunar construction materials utilizing indigenous resources rather than transporting needed materials from earth. Lunar concrete (made from Hydraulic Cement and lunar soil) has been studied and suggested as the construction material of choice for some of the lunar projects. Unfortunately, its hydration requires water which is going to be a precious commodity on the moon. Therefore this study explores the feasibility of using binders other than hydraulic cement such as sulfur or epoxy with lunar regolith as a construction material. This report describes findings of this study which deals specifically with using molten sulfur as a binder for Lunar concrete. It describes laboratory experiments in which the sulfur to lunar soil simulant ratios by weight were varied to study the minimum amount of sulfur required to produce a particular strength. The compressive and tensile strengths of these mixes were evaluated. Metal and fiber glass fibers were added to some of the mixes to study their effects on the compressive and tensile strengths. This report also describes experiments where the sulfur is melted and mixed with the lunar regolith in a specially designed vacuum chamber. The properties of the produced concrete were compared to those of concrete produced under normal pressure.

  6. Fast Thorium Molten Salt Reactors Started with Plutonium

    SciTech Connect

    Merle-Lucotte, E.; Heuer, D.; Le Brun, C.; Brissot, R.; Liatard, E.; Meplan, O.; Nuttin, A.

    2006-07-01

    One of the pending questions concerning Molten Salt Reactors based on the {sup 232}Th/{sup 233}U fuel cycle is the supply of the fissile matter, and as a consequence the deployment possibilities of a fleet of Molten Salt Reactors, since {sup 233}U does not exist on earth and is not yet produced in the current operating reactors. A solution may consist in producing {sup 233}U in special devices containing Thorium, in Pressurized Water or Fast Neutrons Reactors. Two alternatives to produce {sup 233}U are examined here: directly in standard Molten Salt Reactors started with Plutonium as fissile matter and then operated in the Th/{sup 233}U cycle; or in dedicated Molten Salt Reactors started and fed with Plutonium as fissile matter and Thorium as fertile matter. The idea is to design a critical reactor able to burn the Plutonium and the minor actinides presently produced in PWRs, and consequently to convert this Plutonium into {sup 233}U. A particular reactor configuration is used, called 'unique channel' configuration in which there is no moderator in the core, leading to a quasi fast neutron spectrum, allowing Plutonium to be used as fissile matter. The conversion capacities of such Molten Salt Reactors are excellent. For Molten Salt Reactors only started with Plutonium, the assets of the Thorium fuel cycle turn out to be quickly recovered and the reactor's characteristics turn out to be equivalent to Molten Salt Reactors operated with {sup 233}U only. Using a combination of Molten Salt Reactors started or operated with Plutonium and of Molten Salt Reactors started with {sup 233}U, the deployment capabilities of these reactors fully satisfy the condition of sustainability. (authors)

  7. Bovine milk proteome: Quantitative changes in normal milk exosomes, milk fat globule membranes and whey proteomes resulting from Staphylococcus aureus mastitis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Knowledge of milk protein composition/expression in healthy cows and cows with mastitis will provide information important for the dairy food industry, mammary biology and immune function in the mammary gland. To facilitate maximum protein discovery, milk was fractioned into whey, milk fat globule ...

  8. A Possible Regenerative, Molten-Salt, Thermoelectric Fuel Cell

    NASA Technical Reports Server (NTRS)

    Greenberg, Jacob; Thaller, Lawrence H.; Weber, Donald E.

    1964-01-01

    Molten or fused salts have been evaluated as possible thermoelectric materials because of the relatively good values of their figures of merit, their chemical stability, their long liquid range, and their ability to operate in conjunction with a nuclear reactor to produce heat. In general, molten salts are electrolytic conductors; therefore, there will be a transport of materials and subsequent decomposition with the passage of an electric current. It is possible nonetheless to overcome this disadvantage by using the decomposition products of the molten-salt electrolyte in a fuel cell. The combination of a thermoelectric converter and a fuel cell would lead to a regenerative system that may be useful.

  9. Method for the regeneration of spent molten zinc chloride

    DOEpatents

    Zielke, Clyde W.; Rosenhoover, William A.

    1981-01-01

    In a process for regenerating spent molten zinc chloride which has been used in the hydrocracking of coal or ash-containing polynuclear aromatic hydrocarbonaceous materials derived therefrom and which contains zinc chloride, zinc oxide, zinc oxide complexes and ash-containing carbonaceous residue, by incinerating the spent molten zinc chloride to vaporize the zinc chloride for subsequent condensation to produce a purified molten zinc chloride: an improvement comprising the use of clay in the incineration zone to suppress the vaporization of metals other than zinc. Optionally water is used in conjunction with the clay to further suppress the vaporization of metals other than zinc.

  10. Control strategies in a thermal oil - Molten salt heat exchanger

    NASA Astrophysics Data System (ADS)

    Roca, Lidia; Bonilla, Javier; Rodríguez-García, Margarita M.; Palenzuela, Patricia; de la Calle, Alberto; Valenzuela, Loreto

    2016-05-01

    This paper presents a preliminary control scheme for a molten salt - thermal oil heat exchanger. This controller regulates the molten salt mass flow rate to reach and maintain the desired thermal oil temperature at the outlet of the heat exchanger. The controller architecture has been tested using an object-oriented heat exchanger model that has been validated with data from a molten salt testing facility located at CIEMAT-PSA. Different simulations are presented with three different goals: i) to analyze the controller response in the presence of disturbances, ii) to demonstrate the benefits of designing a setpoint generator and iii) to show the controller potential against electricity price variations.

  11. [Interconnection between architecture of protein globule and disposition of conformational conservative oligopeptides in proteins from one protein family].

    PubMed

    Batianovskiĭ, A V; Filatov, I V; Namiot, V A; Esipova, N G; Volotovskiĭ, I D

    2012-01-01

    It was shown that selective interactions between helical segments of macromolecules can realize in globular proteins in the segments characterized by the same periodicities of charge distribution i.e. between conformationally conservative oligopeptides. It was found that in the macromolecules of alpha-helical proteins conformationally conservative oligopeptides are disposed at a distance being characteristic of direct interactions. For representatives of many structural families of alpha-type proteins specific disposition of conformationally conservative segments is observed. This disposition is inherent to a particular structural family. Disposition of conformationally conservative segments is not related to homology of the amino acid sequence but reflects peculiarities of native 3D-architectures of protein globules.

  12. Expression, purification, and characterization of recombinant human and murine milk fat globule-epidermal growth factor-factor 8.

    PubMed

    Castellanos, Erick R; Ciferri, Claudio; Phung, Wilson; Sandoval, Wendy; Matsumoto, Marissa L

    2016-08-01

    Milk fat globule-epidermal growth factor-factor 8 (MFG-E8), as its name suggests, is a major glycoprotein component of milk fat globules secreted by the mammary epithelium. Although its role in milk fat production is unclear, MFG-E8 has been shown to act as a bridge linking apoptotic cells to phagocytes for removal of these dying cells. MFG-E8 is capable of bridging these two very different cell types via interactions through both its epidermal growth factor (EGF)-like domain(s) and its lectin-type C domains. The EGF-like domain interacts with αVβ3 and αVβ5 integrins on the surface of phagocytes, whereas the C domains bind phosphatidylserine found on the surface of apoptotic cells. In an attempt to purify full-length, recombinant MFG-E8 expressed in either insect cells or CHO cells, we find that it is highly aggregated. Systematic truncation of the domain architecture of MFG-E8 indicates that the C domains are mainly responsible for the aggregation propensity. Addition of Triton X-100 to the conditioned cell culture media allowed partial recovery of non-aggregated, full-length MFG-E8. A more comprehensive detergent screen identified CHAPS as a stabilizer of MFG-E8 and allowed purification of a significant portion of non-aggregated, full-length protein. The CHAPS-stabilized recombinant MFG-E8 retained its natural ability to bind both αVβ3 and αVβ5 integrins and phosphatidylserine suggesting that it is properly folded and active. Herein we describe an efficient purification method for production of non-aggregated, full-length MFG-E8.

  13. Expression, purification, and characterization of recombinant human and murine milk fat globule-epidermal growth factor-factor 8.

    PubMed

    Castellanos, Erick R; Ciferri, Claudio; Phung, Wilson; Sandoval, Wendy; Matsumoto, Marissa L

    2016-08-01

    Milk fat globule-epidermal growth factor-factor 8 (MFG-E8), as its name suggests, is a major glycoprotein component of milk fat globules secreted by the mammary epithelium. Although its role in milk fat production is unclear, MFG-E8 has been shown to act as a bridge linking apoptotic cells to phagocytes for removal of these dying cells. MFG-E8 is capable of bridging these two very different cell types via interactions through both its epidermal growth factor (EGF)-like domain(s) and its lectin-type C domains. The EGF-like domain interacts with αVβ3 and αVβ5 integrins on the surface of phagocytes, whereas the C domains bind phosphatidylserine found on the surface of apoptotic cells. In an attempt to purify full-length, recombinant MFG-E8 expressed in either insect cells or CHO cells, we find that it is highly aggregated. Systematic truncation of the domain architecture of MFG-E8 indicates that the C domains are mainly responsible for the aggregation propensity. Addition of Triton X-100 to the conditioned cell culture media allowed partial recovery of non-aggregated, full-length MFG-E8. A more comprehensive detergent screen identified CHAPS as a stabilizer of MFG-E8 and allowed purification of a significant portion of non-aggregated, full-length protein. The CHAPS-stabilized recombinant MFG-E8 retained its natural ability to bind both αVβ3 and αVβ5 integrins and phosphatidylserine suggesting that it is properly folded and active. Herein we describe an efficient purification method for production of non-aggregated, full-length MFG-E8. PMID:27102803

  14. Physical properties and formation of MCLD 126.6+24.5 : a dense cometary shape globule at high-Galactic latitude

    NASA Astrophysics Data System (ADS)

    Ristorcelli, Isabelle; Rivera-Ingraham, Alana; Juvela, Mika; Falgarone, Edith; Pelkonen, Veli-Matti; Pagani, Laurent; Ysard, Nathalie; Montier, Ludovic; Montillaud, Julien; Marshall, Douglas; Bernard, Jean-Philippe

    2015-08-01

    The high-latitude molecular clouds are mostly gravitationally unbound and an interesting question to be investigated is how dense cores can form in such tenuous, diffuse environment, and what is their ability to form stars. Are these dense cores forming from random fluctuations in a turbulent medium, or is their formation triggered by external mechanisms ?We present here a detailed analysis of the dense high-latitude clump MCLD 126.6+24.5 observed with PACS and SPIRE as part of the Herschel Key-Program ‘Galactic Cold Cores’, a follow-up of Planck detections. The clump lies in a tenuous high-latitude cloud, located at the border of the Polaris Flare, a large molecular cirrus cloud in the direction of the north celestial pole, at an estimated distance of 150 pc. Its cometary globule shape appears similar to what is usually found in globules in active star formation regions, although this nebula is far from any such region.The column density distribution derived from the Herschel data shows a very sharp edge and narrow transition between the diffuse medium and the molecular part of the cloud. This remarkable feature could be the signature of a shocked-compression flow from its southern side, likely associated with the North Celestial Pole HI loop. Cold cores are found embedded inside the globule, with temperatures down to 10K. We also analyse the properties of its 2 main filaments (including a pillar-like structure). We present their main characteristics, both in terms of dust and gas physical properties, combining the Herschel data with IRAM maps of 13CO and C18O. We compare the overall properties of the globule and its structure with predictions from MHD simulations in order to investigate the origin of this intriguing cometary shape globule found in high-galactic latitude diffuse environment.

  15. Magnetic Gate System for Molten Metal Flow Control

    SciTech Connect

    2001-02-01

    Electromagnetics Offer Many Advantages For Better Control Of The Molten Steel. Over 80 percent of all of the world's yearly steel production or approximately 650 million tons, is produced by the continuous casting process.

  16. 19. Inside the cast house at Furnace A. Molten iron ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Inside the cast house at Furnace A. Molten iron flowed into eight ladles. The furnace was cast (or tapped) six times each day. - Central Furnaces, 2650 Broadway, east bank of Cuyahoga River, Cleveland, Cuyahoga County, OH

  17. System Requirements Document for the Molten Salt Reactor Experiment

    SciTech Connect

    Aigner, R.D.

    2000-04-01

    The purpose of the conversion process is to convert the {sup 233}U fluoride compounds that are being extracted from the Molten Salt Reactor Experiment (MSRE) equipment to a stable oxide for long-term storage at Bldg. 3019.

  18. Polymers' surface interactions with molten iron: A theoretical study

    NASA Astrophysics Data System (ADS)

    Assadi, M. Hussein N.; Sahajwalla, Veena

    2014-10-01

    Environmental concerns are the chief drive for more innovative recycling techniques for end-of-life polymeric products. One attractive option is taking advantage of C and H content of polymeric waste in steelmaking industry. In this work, we examined the interaction of two high production polymers i.e. polyurethane and polysulfide with molten iron using ab initio molecular dynamics simulation. We demonstrate that both polymers can be used as carburizers for molten iron. Additionally, we found that light weight H2 and CHx molecules were released as by-products of the polymer-molten iron interaction. The outcomes of this study will have applications in the carburization of molten iron during ladle metallurgy and waste plastic injection in electric arc furnace.

  19. Degassing of molten alloys with the assistance of ultrasonic vibration

    DOEpatents

    Han, Qingyou; Xu, Hanbing; Meek, Thomas T.

    2010-03-23

    An apparatus and method are disclosed in which ultrasonic vibration is used to assist the degassing of molten metals or metal alloys thereby reducing gas content in the molten metals or alloys. High-intensity ultrasonic vibration is applied to a radiator that creates cavitation bubbles, induces acoustic streaming in the melt, and breaks up purge gas (e.g., argon or nitrogen) which is intentionally introduced in a small amount into the melt in order to collect the cavitation bubbles and to make the cavitation bubbles survive in the melt. The molten metal or alloy in one version of the invention is an aluminum alloy. The ultrasonic vibrations create cavitation bubbles and break up the large purge gas bubbles into small bubbles and disperse the bubbles in the molten metal or alloy more uniformly, resulting in a fast and clean degassing.

  20. Boric ester-type molten salt via dehydrocoupling reaction.

    PubMed

    Matsumi, Noriyoshi; Toyota, Yoshiyuki; Joshi, Prerna; Puneet, Puhup; Vedarajan, Raman; Takekawa, Toshihiro

    2014-11-14

    Novel boric ester-type molten salt was prepared using 1-(2-hydroxyethyl)-3-methylimidazolium chloride as a key starting material. After an ion exchange reaction of 1-(2-hydroxyethyl)-3-methylimidazolium chloride with lithium (bis-(trifluoromethanesulfonyl) imide) (LiNTf2), the resulting 1-(2-hydroxyethyl)-3-methylimidazolium NTf2 was reacted with 9-borabicyclo[3.3.1]nonane (9-BBN) to give the desired boric ester-type molten salt in a moderate yield. The structure of the boric ester-type molten salt was supported by 1H-, 13C-, 11B- and 19F-NMR spectra. In the presence of two different kinds of lithium salts, the matrices showed an ionic conductivity in the range of 1.1 × 10⁻⁴-1.6 × 10⁻⁵ S cm⁻¹ at 51 °C. This was higher than other organoboron molten salts ever reported.

  1. CONTAINMENT SYSTEM, SPRAY CHAMBER, LOOKING NORTH WITH MIST COOLING MOLTEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CONTAINMENT SYSTEM, SPRAY CHAMBER, LOOKING NORTH WITH MIST COOLING MOLTEN STEEL SLABS AS THEY PROGRESS THROUGH THIS CHAMBER. - U.S. Steel, Fairfield Works, Continuous Caster, Fairfield, Jefferson County, AL

  2. Separation of actinides from lanthanides utilizing molten salt electrorefining

    SciTech Connect

    Grimmett, D.L.; Fusselman, S.P.; Roy, J.J.; Gay, R.L.; Krueger, C.L.; Storvick, T.S.; Inoue, T.; Hijikata, T.; Takahashi, N.

    1996-10-01

    TRUMP-S (TRansUranic Management through Pyropartitioning Separation) is a pyrochemical process being developed to separate actinides form fission products in nuclear waste. A key process step involving molten salt electrorefining to separate actinides from lanthanides has been studied on a laboratory scale. Electrorefining of U, Np, Pu, Am, and lanthanide mixtures from molten cadmium at 450 C to a solid cathode utilizing a molten chloride electrolyte resulted in > 99% removal of actinides from the molten cadmium and salt phases. Removal of the last few percent of actinides is accompanied by lowered cathodic current efficiency and some lanthanide codeposition. Actinide/lanthanide separation ratios on the cathode are ordered U > Np > Pu > Am and are consistent with predictions based on equilibrium potentials.

  3. Molten salt electrolyte battery cell with overcharge tolerance

    DOEpatents

    Kaun, Thomas D.; Nelson, Paul A.

    1989-01-01

    A molten salt electrolyte battery having an increased overcharge tolerance employs a negative electrode with two lithium alloy phases of different electrochemical potential, one of which allows self-discharge rates which permits battery cell equalization.

  4. WORKER REMOVING SLAG FROM THE MOLTEN METAL BATH IN THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    WORKER REMOVING SLAG FROM THE MOLTEN METAL BATH IN THE ELECTRIC FURNACE AFTER ADDING A CHEMICAL COAGULANT TO FORCE IT TO THE SURFACE. - Southern Ductile Casting Company, Melting, 2217 Carolina Avenue, Bessemer, Jefferson County, AL

  5. Pressurized tundish for controlling a continuous flow of molten metal

    DOEpatents

    Lewis, Thomas W.; Hamill, Jr., Paul E.; Ozgu, Mustafa R.; Padfield, Ralph C.; Rego, Donovan N.; Brita, Guido P.

    1990-01-01

    A pressurized tundish for controlling a continous flow of molten metal characterized by having a pair of principal compartments, one being essentially unpressurized and receiving molten metal introduced thereto, and the other being adapted for maintaining a controlled gaseous pressure over the surface of the fluid metal therein, whereby, by controlling the pressure within the pressurized chamber, metal exiting from the tundish is made to flow continually and at a controlled rate.

  6. Pressurized tundish for controlling a continuous flow of molten metal

    DOEpatents

    Lewis, T.W.; Hamill, P.E. Jr.; Ozgu, M.R.; Padfield, R.C.; Rego, D.N.; Brita, G.P.

    1990-07-24

    A pressurized tundish for controlling a continuous flow of molten metal is characterized by having a pair of principal compartments, one being essentially unpressurized and receiving molten metal introduced thereto, and the other being adapted for maintaining a controlled gaseous pressure over the surface of the fluid metal therein, whereby, by controlling the pressure within the pressurized chamber, metal exiting from the tundish is made to flow continually and at a controlled rate. 1 fig.

  7. Are diamond nanoparticles cytotoxic?

    PubMed

    Schrand, Amanda M; Huang, Houjin; Carlson, Cataleya; Schlager, John J; Omacr Sawa, Eiji; Hussain, Saber M; Dai, Liming

    2007-01-11

    Finely divided carbon particles, including charcoal, lampblack, and diamond particles, have been used for ornamental and official tattoos since ancient times. With the recent development in nanoscience and nanotechnology, carbon-based nanomaterials (e.g., fullerenes, nanotubes, nanodiamonds) attract a great deal of interest. Owing to their low chemical reactivity and unique physical properties, nanodiamonds could be useful in a variety of biological applications such as carriers for drugs, genes, or proteins; novel imaging techniques; coatings for implantable materials; and biosensors and biomedical nanorobots. Therefore, it is essential to ascertain the possible hazards of nanodiamonds to humans and other biological systems. We have, for the first time, assessed the cytotoxicity of nanodiamonds ranging in size from 2 to 10 nm. Assays of cell viability such as mitochondrial function (MTT) and luminescent ATP production showed that nanodiamonds were not toxic to a variety of cell types. Furthermore, nanodiamonds did not produce significant reactive oxygen species. Cells can grow on nanodiamond-coated substrates without morphological changes compared to controls. These results suggest that nanodiamonds could be ideal for many biological applications in a diverse range of cell types.

  8. Are diamond nanoparticles cytotoxic?

    PubMed

    Schrand, Amanda M; Huang, Houjin; Carlson, Cataleya; Schlager, John J; Omacr Sawa, Eiji; Hussain, Saber M; Dai, Liming

    2007-01-11

    Finely divided carbon particles, including charcoal, lampblack, and diamond particles, have been used for ornamental and official tattoos since ancient times. With the recent development in nanoscience and nanotechnology, carbon-based nanomaterials (e.g., fullerenes, nanotubes, nanodiamonds) attract a great deal of interest. Owing to their low chemical reactivity and unique physical properties, nanodiamonds could be useful in a variety of biological applications such as carriers for drugs, genes, or proteins; novel imaging techniques; coatings for implantable materials; and biosensors and biomedical nanorobots. Therefore, it is essential to ascertain the possible hazards of nanodiamonds to humans and other biological systems. We have, for the first time, assessed the cytotoxicity of nanodiamonds ranging in size from 2 to 10 nm. Assays of cell viability such as mitochondrial function (MTT) and luminescent ATP production showed that nanodiamonds were not toxic to a variety of cell types. Furthermore, nanodiamonds did not produce significant reactive oxygen species. Cells can grow on nanodiamond-coated substrates without morphological changes compared to controls. These results suggest that nanodiamonds could be ideal for many biological applications in a diverse range of cell types. PMID:17201422

  9. Novel waste printed circuit board recycling process with molten salt.

    PubMed

    Riedewald, Frank; Sousa-Gallagher, Maria

    2015-01-01

    The objective of the method was to prove the concept of a novel waste PCBs recycling process which uses inert, stable molten salts as the direct heat transfer fluid and, simultaneously, uses this molten salt to separate the metal products in either liquid (solder, zinc, tin, lead, etc.) or solid (copper, gold, steel, palladium, etc.) form at the operating temperatures of 450-470 °C. The PCB recovery reactor is essentially a U-shaped reactor with the molten salt providing a continuous fluid, allowing molten salt access from different depths for metal recovery. A laboratory scale batch reactor was constructed using 316L as suitable construction material. For safety reasons, the inert, stable LiCl-KCl molten salts were used as direct heat transfer fluid. Recovered materials were washed with hot water to remove residual salt before metal recovery assessment. The impact of this work was to show metal separation using molten salts in one single unit, by using this novel reactor methodology. •The reactor is a U-shaped reactor filled with a continuous liquid with a sloped bottom representing a novel reactor concept.•This method uses large PCB pieces instead of shredded PCBs as the reactor volume is 2.2 L.•The treated PCBs can be removed via leg B while the process is on-going.

  10. Novel waste printed circuit board recycling process with molten salt

    PubMed Central

    Riedewald, Frank; Sousa-Gallagher, Maria

    2015-01-01

    The objective of the method was to prove the concept of a novel waste PCBs recycling process which uses inert, stable molten salts as the direct heat transfer fluid and, simultaneously, uses this molten salt to separate the metal products in either liquid (solder, zinc, tin, lead, etc.) or solid (copper, gold, steel, palladium, etc.) form at the operating temperatures of 450–470 °C. The PCB recovery reactor is essentially a U-shaped reactor with the molten salt providing a continuous fluid, allowing molten salt access from different depths for metal recovery. A laboratory scale batch reactor was constructed using 316L as suitable construction material. For safety reasons, the inert, stable LiCl–KCl molten salts were used as direct heat transfer fluid. Recovered materials were washed with hot water to remove residual salt before metal recovery assessment. The impact of this work was to show metal separation using molten salts in one single unit, by using this novel reactor methodology. • The reactor is a U-shaped reactor filled with a continuous liquid with a sloped bottom representing a novel reactor concept. • This method uses large PCB pieces instead of shredded PCBs as the reactor volume is 2.2 L. • The treated PCBs can be removed via leg B while the process is on-going. PMID:26150977

  11. Novel waste printed circuit board recycling process with molten salt.

    PubMed

    Riedewald, Frank; Sousa-Gallagher, Maria

    2015-01-01

    The objective of the method was to prove the concept of a novel waste PCBs recycling process which uses inert, stable molten salts as the direct heat transfer fluid and, simultaneously, uses this molten salt to separate the metal products in either liquid (solder, zinc, tin, lead, etc.) or solid (copper, gold, steel, palladium, etc.) form at the operating temperatures of 450-470 °C. The PCB recovery reactor is essentially a U-shaped reactor with the molten salt providing a continuous fluid, allowing molten salt access from different depths for metal recovery. A laboratory scale batch reactor was constructed using 316L as suitable construction material. For safety reasons, the inert, stable LiCl-KCl molten salts were used as direct heat transfer fluid. Recovered materials were washed with hot water to remove residual salt before metal recovery assessment. The impact of this work was to show metal separation using molten salts in one single unit, by using this novel reactor methodology. •The reactor is a U-shaped reactor filled with a continuous liquid with a sloped bottom representing a novel reactor concept.•This method uses large PCB pieces instead of shredded PCBs as the reactor volume is 2.2 L.•The treated PCBs can be removed via leg B while the process is on-going. PMID:26150977

  12. Molten metal reactor and method of forming hydrogen, carbon monoxide and carbon dioxide using the molten alkaline metal reactor

    DOEpatents

    Bingham, Dennis N.; Klingler, Kerry M.; Turner, Terry D.; Wilding, Bruce M.

    2012-11-13

    A molten metal reactor for converting a carbon material and steam into a gas comprising hydrogen, carbon monoxide, and carbon dioxide is disclosed. The reactor includes an interior crucible having a portion contained within an exterior crucible. The interior crucible includes an inlet and an outlet; the outlet leads to the exterior crucible and may comprise a diffuser. The exterior crucible may contain a molten alkaline metal compound. Contained between the exterior crucible and the interior crucible is at least one baffle.

  13. Rechargable molten-electrolyte lithium batteries

    NASA Astrophysics Data System (ADS)

    Kaun, T. D.

    1989-10-01

    Lithium-alloy/metal sulfide cells with on molten-halide electrolytes, which are operated in a temperature range of 375 to 474 C, have undergone many improvements in recent years. Cycle life now exceeds 1000 cycles. The Li-alloy/LiCl-LiBr-KBr eutectic (25:37:38 mol percent)/upper-plateau (U.P.) FeS2 cell operated at 400 C has shown excellence performance prospects: 200 Wh/kg specific energy and 200-W/kg specific power. Electrolyte composition has played a dominant role in attaining long-term stable electrochemical performance. A modified LiCl-LiBr-KBr composition (34:32.5:33.5 mol percent) was found to exhibit 25 percent increased ionic conductivity over that of the eutectic. This higher-conductivity electrolyte approximately compensates for the reduced electrolyte content of the electrolyte-starved FeS2 cell. Such a cell has attained of 95 percent utilization of U.P. FeS2 electrode capacity at a comparable cell impedance (0.8 to 1.0 ohm sq cm) to that of an electrolyte-flooded cell. Advancements in cell design and materials application have reduced materials costs and increased battery durability. Both FeS and FeS2 cell tests have demonstrated overcharge tolerance (3 to 5 mA/sq cm) for electrolyte-starved operation with MgO powder separators.

  14. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-09-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  15. Molten aluminum alloy fuel fragmentation experiments

    SciTech Connect

    Gabor, J.D.; Purviance, R.T.; Cassulo, J.C.; Spencer, B.W.

    1992-01-01

    Experiments were conducted in which molten aluminum alloys were injected into a 1.2 m deep pool of water. The parameters varied were (i) injectant material (8001 aluminum alloy and 12.3 wt% U-87.7 wt% Al), (ii) melt superheat (O to 50 K), (iii) water temperature (313, 343 and 373 K) and (iv) size and geometry of the pour stream (5, 10 and 20 mm diameter circular and 57 mm annular). The pour stream fragmentation was dominated by surface tension with large particles ({approximately}30 mm) being formed from varicose wave breakup of the 10-mm circular pours and from the annular flow off a 57 mm diameter tube. The fragments produced by the 5 mm circular et were smaller ({approximately} mm), and the 20 mm jet which underwent sinuous wave breakup produced {approximately}100 mm fragments. The fragments froze to form solid particles in 313 K water, and when the water was {ge}343 K, the melt fragments did not freeze during their transit through 1.2 m of water.

  16. Dissipative particle dynamics simulations of the viscosities of molten TNT and molten TNT suspensions containing nanoparticles.

    PubMed

    Zhou, Yang; Li, Yixue; Qian, Wen; He, Bi

    2016-09-01

    Based on dissipative particle dynamics (DPD) methods and experimental data, we used an empirical relationship between the DPD temperature and the real temperature to build a model that describes the viscosity of molten TNT fluids. The errors in the predicted viscosity based on this model were no more than 2.3 %. We also studied the steady-state shear rheological behavior of molten TNT fluids containing nanoparticles ("nanofluids"). The dependence of the nanofluid viscosity on the temperature was found to satisfy an Arrhenius-type equation, η = Ae (B/T) , where B, the flow activation energy, depends on particle content, size, and shape. We modified the Einstein-type viscosity model to account for the effects of nanoparticle solvation in TNT nanofluids. The resulting model was able to correctly predict the viscosities of suspensions containing nano- to microsized particles, and did not require any changes to the physical background of Einstein's viscosity theory. Graphical Abstract The revised Einstein viscosity model that correctly predict the viscosity of TNT suspensions containing nanoparticles. PMID:27553301

  17. Supported Molten Metal Catalysis. A New Class of Catalysts

    SciTech Connect

    Ravindra Datta; Ajeet Singh; Manuela Serban; Istvan Halasz

    2006-06-02

    We describe a new class of heterogeneous catalysts called supported molten metal catalysis (SMMC), in which molten metal catalysts are dispersed as nanodroplets on the surface of porous supports, allowing much larger active surface area than is possible in conventional contacting techniques for catalytic metals that are molten under reaction conditions, thus greatly enhancing their activity and potential utility. Specific examples of different types of reactions are provided to demonstrate the broad applicability of the technique in designing active, selective, and stable new catalysts. It is shown that dispersing the molten metal on a support in the suggested manner can enhance the rate of a reaction by three to four orders of magnitude as a result of the concomitant increase in the active surface area. New reaction examples include {gamma}-Al{sub 2}O{sub 3} supported molten Te (melting point 450 C) and Ga (MP 30 C) catalysts for bifunctional methylcyclohexane dehydrogenation. These catalysts provide activity similar to conventional Pt-based catalysts for this with better resistance to coking. In addition, results are described for a controlled pore glass supported molten In (MP 157 C) catalyst for the selective catalytic reduction of NO with ethanol in the presence of water, demonstrating activities superior to conventional catalysts for this reaction. A discussion is also provided on the characterization of the active surface area and dispersion of these novel supported catalysts. It is clear based on the results described that the development of new active and selective supported molten metal catalysts for practical applications is entirely plausible.

  18. Shear rheology of molten crumb chocolate.

    PubMed

    Taylor, J E; Van Damme, I; Johns, M L; Routh, A F; Wilson, D I

    2009-03-01

    The shear rheology of fresh molten chocolate produced from crumb was studied over 5 decades of shear rate using controlled stress devices. The Carreau model was found to be a more accurate description than the traditional Casson model, especially at shear rates between 0.1 and 1 s(-1). At shear rates around 0.1 s(-1) (shear stress approximately 7 Pa) the material exhibited a transition to a solid regime, similar to the behavior reported by Coussot (2005) for other granular suspensions. The nature of the suspension was explored by investigating the effect of solids concentration (0.20 < phi < 0.75) and the nature of the particles. The rheology of the chocolate was then compared with the rheology of (1) a synthetic chocolate, which contained sunflower oil in place of cocoa butter, and (2) a suspension of sugar of a similar size distribution (volume mean 15 mum) in cocoa butter and emulsifier. The chocolate and synthetic chocolate showed very similar rheological profiles under both steady shear and oscillatory shear. The chocolate and the sugar suspension showed similar Krieger-Dougherty dependency on volume fraction, and a noticeable transition to a stiff state at solids volume fractions above approximately 0.5. Similar behavior has been reported by Citerne and others (2001) for a smooth peanut butter, which had a similar particle size distribution and solids loading to chocolate. The results indicate that the melt rheology of the chocolate is dominated by hydrodynamic interactions, although at high solids volume fractions the emulsifier may contribute to the departure of the apparent viscosity from the predicted trend.

  19. Gasification characteristics of organic waste by molten salt

    NASA Astrophysics Data System (ADS)

    Sugiura, Kimihiko; Minami, Keishi; Yamauchi, Makoto; Morimitsu, Shinsuke; Tanimoto, Kazumi

    Recently, along with the growth in economic development, there has been a dramatic accompanying increase in the amount of sludge and organic waste. The disposal of such is a significant problem. Moreover, there is also an increased in the consumption of electricity along with economic growth. Although new energy development, such as fuel cells, has been promoted to solve the problem of power consumption, there has been little corresponding promotion relating to the disposal of sludge and organic waste. Generally, methane fermentation comprises the primary organic waste fuel used in gasification systems. However, the methane fermentation method takes a long time to obtain the fuel gas, and the quality of the obtained gas is unstable. On the other hand, gasification by molten salt is undesirable because the molten salt in the gasification gas corrodes the piping and turbine blades. Therefore, a gasification system is proposed by which the sludge and organic waste are gasified by molten salt. Moreover, molten carbonate fuel cells (MCFC) are needed to refill the MCFC electrolyte volatilized in the operation. Since the gasification gas is used as an MCFC fuel, MCFC electrolyte can be provided with the fuel gas. This paper elucidates the fundamental characteristics of sludge and organic waste gasification. A crucible filled with the molten salt comprising 62 Li 2CO 3/38 K 2CO 3, is installed in the reaction vessel, and can be set to an arbitrary temperature in a gas atmosphere. In this instance, the gasifying agent gas is CO 2. Sludge or the rice is supplied as organic waste into the molten salt, and is gasified. The chemical composition of the gasification gas is analyzed by a CO/CO 2 meter, a HC meter, and a SO x meter gas chromatography. As a result, although sludge can generate CO and H 2 near the chemical equilibrium value, all of the sulfur in the sludge is not fixed in the molten salt, because the sludge floats on the surface of the carbonate by the specific

  20. LIFE Materails: Molten-Salt Fuels Volume 8

    SciTech Connect

    Moir, R; Brown, N; Caro, A; Farmer, J; Halsey, W; Kaufman, L; Kramer, K; Latkowski, J; Powers, J; Shaw, H; Turchi, P

    2008-12-11

    The goals of the Laser Inertial Fusion Fission Energy (LIFE) is to use fusion neutrons to fission materials with no enrichment and minimum processing and have greatly reduced wastes that are not of interest to making weapons. Fusion yields expected to be achieved in NIF a few times per day are called for with a high reliable shot rate of about 15 per second. We have found that the version of LIFE using TRISO fuel discussed in other volumes of this series can be modified by replacing the molten-flibe-cooled TRISO fuel zone with a molten salt in which the same actinides present in the TRISO particles are dissolved in the molten salt. Molten salts have the advantage that they are not subject to radiation damage, and hence overcome the radiation damage effects that may limit the lifetime of solid fuels such as TRISO-containing pebbles. This molten salt is pumped through the LIFE blanket, out to a heat exchanger and back into the blanket. To mitigate corrosion, steel structures in contact with the molten salt would be plated with tungsten or nickel. The salt will be processed during operation to remove certain fission products (volatile and noble and semi-noble fission products), impurities and corrosion products. In this way neutron absorbers (fission products) are removed and neutronics performance of the molten salt is somewhat better than that of the TRISO fuel case owing to the reduced parasitic absorption. In addition, the production of Pu and rare-earth elements (REE) causes these elements to build up in the salt, and leads to a requirement for a process to remove the REE during operation to insure that the solubility of a mixed (Pu,REE)F3 solid solution is not exceeded anywhere in the molten salt system. Removal of the REE will further enhance the neutronics performance. With molten salt fuels, the plant would need to be safeguarded because materials of interest for weapons are produced and could potentially be removed.

  1. Application of lithium in molten-salt reduction processes.

    SciTech Connect

    Gourishankar, K. V.

    1998-11-11

    Metallothermic reductions have been extensively studied in the field of extractive metallurgy. At Argonne National Laboratory (ANL), we have developed a molten-salt based reduction process using lithium. This process was originally developed to reduce actinide oxides present in spent nuclear fuel. Preliminary thermodynamic considerations indicate that this process has the potential to be adapted for the extraction of other metals. The reduction is carried out at 650 C in a molten-salt (LiCl) medium. Lithium oxide (Li{sub 2}O), produced during the reduction of the actinide oxides, dissolves in the molten salt. At the end of the reduction step, the lithium is regenerated from the salt by an electrowinning process. The lithium and the salt from the electrowinning are then reused for reduction of the next batch of oxide fuel. The process cycle has been successfully demonstrated on an engineering scale in a specially designed pyroprocessing facility. This paper discusses the applicability of lithium in molten-salt reduction processes with specific reference to our process. Results are presented from our work on actinide oxides to highlight the role of lithium and its effect on process variables in these molten-salt based reduction processes.

  2. Viscosity of molten lithium, thorium and beryllium fluorides mixtures

    NASA Astrophysics Data System (ADS)

    Merzlyakov, Alexander V.; Ignatiev, Victor V.; Abalin, Sergei S.

    2011-12-01

    Considering development of Molten Salt Fast Reactor (MSFR) concept, following Molten Salt fluorides mixtures have been chosen as an object for viscosity studies in this work (in mol%): 78LiF-22ThF 4; 71LiF-27ThF 4-2BeF 2 and 75LiF-20ThF 4-5BeF 2. Additionally, the effect of the 3 mol% CeF 3 additives on viscosity of the molten 75LiF-20ThF 4-5BeF 2 (mol%) salt mixture has been investigated experimentally. The method of torsional oscillations of cylindrical crucible filled by molten fluorides mixture has been chosen for kinematic viscosity measurement at temperatures up to 800-850 °C. In temperature ranges, where melts behave as normal liquids, dependences on viscosity vs. temperature are received: ν = А exp [B/T(K)], where ν - kinematic viscosity, m 2/s; T - temperature, K. The kinematic viscosity Rout mean squares (RMS) estimated in the assumption about dispersion homoscedasticity is (0.04-0.12) × 10 -6 (m 2/s). Discrepancies left in the data of viscosity for molten mixtures of LiF, BeF 2 and ThF 4 received by different researchers need further investigations in this area to be continued.

  3. A statistical theory of coil-to-globule-to-coil transition of a polymer chain in a mixture of good solvents

    NASA Astrophysics Data System (ADS)

    Budkov, Yu. A.; Kolesnikov, A. L.; Kalikin, N. N.; Kiselev, M. G.

    2016-05-01

    We present an off-lattice statistical model of a single polymer chain in mixed-solvent media. Taking into account the polymer conformational entropy, renormalization of solvent composition near the polymer backbone, the universal intermolecular excluded-volume and van der Waals interactions within the self-consistent field theory, the reentrant coil-to-globule-to-coil transition (co-nonsolvency) has been described in this paper. For convenience we split the system volume in two parts: the volume occupied by the polymer chain and the volume of bulk solution. Considering the equilibrium between two sub-volumes, the polymer solvation free energy as a function of radius of gyration and co-solvent mole fraction within internal polymer volume has been obtained. Minimizing the free energy of solvation with respect to its arguments, we show two qulitatively different regimes of co-nonsolvency. Namely, at sufficiently high temperature the reentrant coil-to-globule-to-coil transition proceeds smoothly. On the contrary, when the temperature drops below a certain threshold value a coil-globule transition occurs in the regime of first-order phase transition, i.e., discontinuous changes of the radius of gyration and the local co-solvent mole fraction near the polymer backbone. We show that, when the collapse of the polymer chain takes place, the entropy and enthalpy contributions to the solvation free energy of the globule strongly grow. From the first principles of statistical thermodynamics we confirm earlier speculations based on the MD simulations results that the co-nonsolvency is the essentially enthalpic-entropic effect and is caused by enthalpy-entropy compensation. We show that the temperature dependences of the solution heat capacity change due to the solvation of the polymer chain are in qualitative agreement with the differential scanning calorimetry data for PNIPAM in aqueous methanol.

  4. Rod-to-Globule Transition of pDNA/PEG-Poly(l-Lysine) Polyplex Micelles Induced by a Collapsed Balance Between DNA Rigidity and PEG Crowdedness.

    PubMed

    Tockary, Theofilus A; Osada, Kensuke; Motoda, Yusuke; Hiki, Shigehiro; Chen, Qixian; Takeda, Kaori M; Dirisala, Anjaneyulu; Osawa, Shigehito; Kataoka, Kazunori

    2016-03-01

    The role of poly(ethylene-glycol) (PEG) in rod-shaped polyplex micelle structures, having a characteristic core of folded plasmid DNA (pDNA) and a shell of tethered PEG chains, is investigated using PEG-detachable polyplex micelles. Rod shapes undergo change to compacted globule shapes by removal of PEG from polyplex micelles prepared from block copolymer with acid-labile linkage between PEG and poly(l-lysine) (PLys) through exposure to acidic milieu. This structural change supports the previous investigation on the rod shapes that PEG shell prevents the DNA structure from being globule shaped as the most favored structure in minimizing surface area. Noteworthy, despite the PEG is continuously depleted, the structural change does not occur in gradual shortening manner but the rod shapes keep their length unchanged and abruptly transform into globule shapes. Analysis of PEG density reveals the transition occurred when tethered PEG of rod shapes has decreased to a critical crowdedness, i.e., discontacted with neighboring PEG, which eventually illuminates another contribution, rigidity of DNA packaged as bundle in the rod shapes, in addition to the steric repulsion of PEG, in sustaining rod shapes. This investigation affirms significant role of PEG and also DNA rigidity as bundle in the formation of rod-shaped structures enduring the quest of compaction of charge-neutralized DNA in the polyplex micelles.

  5. Sub-Micrometer-Scale Mapping of Magnetite Crystals and Sulfur Globules in Magnetotactic Bacteria Using Confocal Raman Micro-Spectrometry

    PubMed Central

    Eder, Stephan H. K.; Gigler, Alexander M.; Hanzlik, Marianne; Winklhofer, Michael

    2014-01-01

    The ferrimagnetic mineral magnetite is biomineralized by magnetotactic microorganisms and a diverse range of animals. Here we demonstrate that confocal Raman microscopy can be used to visualize chains of magnetite crystals in magnetotactic bacteria, even though magnetite is a poor Raman scatterer and in bacteria occurs in typical grain sizes of only 35–120 nm, well below the diffraction-limited optical resolution. When using long integration times together with low laser power (<0.25 mW) to prevent laser induced damage of magnetite, we can identify and map magnetite by its characteristic Raman spectrum (303, 535, 665 ) against a large autofluorescence background in our natural magnetotactic bacteria samples. While greigite (cubic ; Raman lines of 253 and 351 ) is often found in the Deltaproteobacteria class, it is not present in our samples. In intracellular sulfur globules of Candidatus Magnetobacterium bavaricum (Nitrospirae), we identified the sole presence of cyclo-octasulfur (: 151, 219, 467 ), using green (532 nm), red (638 nm) and near-infrared excitation (785 nm). The Raman-spectra of phosphorous-rich intracellular accumulations point to orthophosphate in magnetic vibrios and to polyphosphate in magnetic cocci. Under green excitation, the cell envelopes are dominated by the resonant Raman lines of the heme cofactor of the b or c-type cytochrome, which can be used as a strong marker for label-free live-cell imaging of bacterial cytoplasmic membranes, as well as an indicator for the redox state. PMID:25233081

  6. Stat3 controls cell death during mammary gland involution by regulating uptake of milk fat globules and lysosomal membrane permeabilization

    PubMed Central

    Resemann, Henrike K.; Ramos-Montoya, Antonio; Skepper, Jeremy; Watson, Christine J.

    2014-01-01

    We have previously demonstrated that Stat3 regulates lysosomal mediated-programmed cell death (LM-PCD) during mouse mammary gland involution in vivo. However, the mechanism that controls the release of lysosomal cathepsins to initiate cell death in this context has not been elucidated. We show here that Stat3 regulates the formation of large lysosomal vacuoles that contain triglyceride. Furthermore, we demonstrate that milk fat globules (MFGs) are toxic to epithelial cells and that, when applied to purified lysosomes, the MFG hydrolysate oleic acid potently induces lysosomal leakiness. Additionally, uptake of secreted MFGs coated in butyrophilin 1A1 is diminished in Stat3 ablated mammary glands while loss of the phagocytosis bridging molecule MFG-E8 results in reduced leakage of cathepsins in vivo. We propose that Stat3 regulates LM-PCD in mouse mammary gland by switching cellular function from secretion to uptake of MFGs. Thereafter, perturbation of lysosomal vesicle membranes by high levels of free fatty acids results in controlled leakage of cathepsins culminating in cell death. PMID:25283994

  7. The presence of HLA-DR antigens on lactating human breast epithelium and milk fat globule membranes.

    PubMed Central

    Newman, R A; Ormerod, M G; Greaves, M F

    1980-01-01

    HLA-DR antigens have been demonstrated on the secretory epithelia of lactating breast using rabbit anti-p28,33 ('Ia-like') and mouse monoclonal anti-HLA-DR 'framework'. Normal non-lactating breast, benign or malignant tumours, epithelial cells from normal breast or isolated from milk and a presumptive breast carcinoma cell line (MCF-7) were all HLA-DR-negative. HLA-DR, HLA (ABC 'framework') and beta 2-microglobulin determinants were also demonstrated on the surface of milk fat globules (MFG) which were unreactive with monoclonal antibodies to thymus cells or leucocytes. A monoclonal antibody detecting allelic HLA-DR determinants (HLA-DRw 1,2,6) was positive on 40% of MFG samples tested, positive reactions being concordant, when tested, with blood B lymphocytes. Antisera raised against MFG membranes also contain anti-HLA-DR activity. Whether the breast epithelial cells synthesize HLA-DR molecules or acquire these passively from mononuclear cells which infiltrate during lactation is not yet resolved. Images Fig. 1 PMID:7002399

  8. Corresponding-states data correlations and molten salts viscosities

    SciTech Connect

    Janz, G.J.; Yamamura, T.; Hansen, M.D.

    1989-01-01

    Transport properties of molten salts are encountered in a broad range of R D tasks, particularly in areas of high-temperature thermal energy storage and in advanced battery concepts. This communication examines a semiempirical corresponding-states correlation as a predictive method using molten salts viscosities. Predictive calculations with molten NaCl and KNO/sub 3/ as model systems, and with calibration quality data sets as the reference base, are used to evaluate this method. While the proper slope for the temperature dependence is forecast, the quality of the predicted data depend directly on the accuracy level of the one experimental value that is the seed for the calculations. Some results are described to show how such calculations have proved useful in guiding value judgments in studies of the viscosity data in the open scientific literature.

  9. Modelling of molten fuel/concrete interactions. [PWR; BWR

    SciTech Connect

    Muir, J. F.; Benjamin, A. S.

    1980-01-01

    A computer program modelling the interaction between molten core materials and structural concrete (CORCON) is being developed to provide quantitative estimates of fuel-melt accident consequences suitable for risk assessment of light water reactors. The principal features of CORCON are reviewed. Models developed for the principal interaction phenomena, inter-component heat transfer, concrete erosion, and melt/gas chemical reactions, are described. Alternative models for the controlling phenomenon, heat transfer from the molten pool to the surrounding concrete, are presented. These models, formulated in conjunction with the development of CORCON, are characterized by the presence or absence of either a gas film or viscous layer of molten concrete at the melt/concrete interface. Predictions of heat transfer based on these models compare favorably with available experimental data.

  10. Injector nozzle for molten salt destruction of energetic waste materials

    DOEpatents

    Brummond, William A.; Upadhye, Ravindra S.

    1996-01-01

    An injector nozzle has been designed for safely injecting energetic waste materials, such as high explosives, propellants, and rocket fuels, into a molten salt reactor in a molten salt destruction process without premature detonation or back burn in the injection system. The energetic waste material is typically diluted to form a fluid fuel mixture that is injected rapidly into the reactor. A carrier gas used in the nozzle serves as a carrier for the fuel mixture, and further dilutes the energetic material and increases its injection velocity into the reactor. The injector nozzle is cooled to keep the fuel mixture below the decomposition temperature to prevent spontaneous detonation of the explosive materials before contact with the high-temperature molten salt bath.

  11. Injector nozzle for molten salt destruction of energetic waste materials

    DOEpatents

    Brummond, W.A.; Upadhye, R.S.

    1996-02-13

    An injector nozzle has been designed for safely injecting energetic waste materials, such as high explosives, propellants, and rocket fuels, into a molten salt reactor in a molten salt destruction process without premature detonation or back burn in the injection system. The energetic waste material is typically diluted to form a fluid fuel mixture that is injected rapidly into the reactor. A carrier gas used in the nozzle serves as a carrier for the fuel mixture, and further dilutes the energetic material and increases its injection velocity into the reactor. The injector nozzle is cooled to keep the fuel mixture below the decomposition temperature to prevent spontaneous detonation of the explosive materials before contact with the high-temperature molten salt bath. 2 figs.

  12. Effects of Stress on Corrosion in a Molten Salt Environment

    NASA Astrophysics Data System (ADS)

    Girdzis, Samuel; Manos, Dennis; Cooke, William

    Molten salt is often used as a heat transfer and energy storage fluid in concentrating solar power plants. Despite its suitable thermal properties, molten salt can present challenges in terms of corrosion. Previous studies have focused extensively on mass loss due to molten salt-induced corrosion. In contrast, we have investigated how corrosion begins and how it changes the surface of stainless steel. Samples of alloys including 304 and 316 stainless steel were exposed to the industry-standard NaNO3-KNO3 (60%-40% by weight) mixture at temperatures over 500°C and then analyzed using Hirox, SEM, and TOF-SIMS. We compare the corrosion at grain boundaries to that within single grain surfaces, showing the effect of the increased internal stresses and the weakened passivation layer. Also, we have examined the enhanced corrosion of samples under mechanical stress, simulating the effects of thermal stresses in a power plant.

  13. Presence of Li clusters in molten LiCl-Li

    DOE PAGES

    Merwin, Augustus; Phillips, William C.; Williamson, Mark A.; Willit, James L.; Motsegood, Perry N.; Chidambaram, Dev

    2016-05-05

    Molten mixtures of lithium chloride and metallic lithium are of significant interest in various metal oxide reduction processes. These solutions have been reported to exhibit seemingly anomalous physical characteristics that lack a comprehensive explanation. ln the current work, the physical chemistry of molten solutions of lithium chloride and metallic lithium, with and without lithium oxide, was investigated using in situ Raman spectroscopy. The Raman spectra obtained from these solutions were in agreement with the previously reported spectrum of the lithium cluster, Li8. Furthermore, this observation is indicative of a nanofluid type colloidal suspension of Li8, in a molten salt matrix.more » It is suggested that the formation and suspension of lithium clusters in lithium chloride is the cause of various phenomena exhibited by these solutions that were previously unexplainable.« less

  14. Presence of Li Clusters in Molten LiCl-Li

    NASA Astrophysics Data System (ADS)

    Merwin, Augustus; Phillips, William C.; Williamson, Mark A.; Willit, James L.; Motsegood, Perry N.; Chidambaram, Dev

    2016-05-01

    Molten mixtures of lithium chloride and metallic lithium are of significant interest in various metal oxide reduction processes. These solutions have been reported to exhibit seemingly anomalous physical characteristics that lack a comprehensive explanation. In the current work, the physical chemistry of molten solutions of lithium chloride and metallic lithium, with and without lithium oxide, was investigated using in situ Raman spectroscopy. The Raman spectra obtained from these solutions were in agreement with the previously reported spectrum of the lithium cluster, Li8. This observation is indicative of a nanofluid type colloidal suspension of Li8 in a molten salt matrix. It is suggested that the formation and suspension of lithium clusters in lithium chloride is the cause of various phenomena exhibited by these solutions that were previously unexplainable.

  15. Presence of Li Clusters in Molten LiCl-Li

    PubMed Central

    Merwin, Augustus; Phillips, William C.; Williamson, Mark A.; Willit, James L.; Motsegood, Perry N.; Chidambaram, Dev

    2016-01-01

    Molten mixtures of lithium chloride and metallic lithium are of significant interest in various metal oxide reduction processes. These solutions have been reported to exhibit seemingly anomalous physical characteristics that lack a comprehensive explanation. In the current work, the physical chemistry of molten solutions of lithium chloride and metallic lithium, with and without lithium oxide, was investigated using in situ Raman spectroscopy. The Raman spectra obtained from these solutions were in agreement with the previously reported spectrum of the lithium cluster, Li8. This observation is indicative of a nanofluid type colloidal suspension of Li8 in a molten salt matrix. It is suggested that the formation and suspension of lithium clusters in lithium chloride is the cause of various phenomena exhibited by these solutions that were previously unexplainable. PMID:27145895

  16. Electrochemical-metallothermic reduction of zirconium in molten salt solutions

    SciTech Connect

    McLaughlin, D.F.; Talko, F.

    1990-05-08

    This patent describes a method for separating hafnium from zirconium of the type wherein a feed containing zirconium and hafnium chlorides is prepared from zirconium-hafnium chloride and the feed is introduced into a distillation column, which distillation column has a reboiler connected at the bottom and a reflux condenser connected at the top and wherein a hafnium chloride enriched stream is taken from the top of the column and a zirconium enriched chloride stream is taken from the bottom of the column. It comprises: reducing the zirconium enriched chloride stream taken from the distillation column to metal by electrochemically reducing an alkaline earth metal in a molten salt bath with the molten salt in the molten salt bath consisting essentially of a mixture of at least one alkali metal chloride and at least one alkaline earth metal chloride and zirconium chloride, with the reduced alkaline earth metal reacting with the zirconium chloride to produce zirconium metal and alkaline earth metal chloride.

  17. Presence of Li Clusters in Molten LiCl-Li.

    PubMed

    Merwin, Augustus; Phillips, William C; Williamson, Mark A; Willit, James L; Motsegood, Perry N; Chidambaram, Dev

    2016-01-01

    Molten mixtures of lithium chloride and metallic lithium are of significant interest in various metal oxide reduction processes. These solutions have been reported to exhibit seemingly anomalous physical characteristics that lack a comprehensive explanation. In the current work, the physical chemistry of molten solutions of lithium chloride and metallic lithium, with and without lithium oxide, was investigated using in situ Raman spectroscopy. The Raman spectra obtained from these solutions were in agreement with the previously reported spectrum of the lithium cluster, Li8. This observation is indicative of a nanofluid type colloidal suspension of Li8 in a molten salt matrix. It is suggested that the formation and suspension of lithium clusters in lithium chloride is the cause of various phenomena exhibited by these solutions that were previously unexplainable. PMID:27145895

  18. The chemistry and status of rechargeable molten-salt batteries

    SciTech Connect

    Cairns, E.J.; Mamantov, G.; Tischer, R.P.; Vissers, D.R.

    1983-05-01

    The chemistry and the state of development of rechargeable molten salt cells and batteries of current interest are reviewed in this work. Molten-salt cells offer the most attractive combination of high specific energy (100-200 Wh/kg), high specific power (50-200 W/kg), and long cycle life (300-1500 cycles) of any rechargeable cells under investigation at this time. It is these important features that justify the development and application of cells that have the disadvantages of operation at elevated temperatures, and difficult materials problems. There are two major categories of molten-salt cells: those in which the molten salt is the sole electrolyte, and those in which the molten salt serves as a reactant and as an auxiliary electrolyte (the main electrolyte is a solid). In the first category are such cells as LiAl/LiCl-KCl/FeS, LiAl/LiCl-KCl/FeS/sub 2/, and Li/sub 4/Si/LiCl-KCl/FeS/sub 2/; in the second category are Na/Na/sub 2/O . xAl/sub 2/O/sub 3//Na/sub 2/S /SUB n/ -S, Na/Na/sup +/ glass/Na/sub 2/S /SUB n/ -S, Na/Na/sub 2/O . xAl/sub 2/O/sub 3//SCl/sub 3/AlCl/sub 4/ in NaCl-AlCl/sub 3/, and Li/Li/sub 2/O/LiNO/sub 3/-KNO/sub 3//V/sub 2/O/sub 5/. These cells have operating temperatures ranging from 150 to 475/sup 0/C, and all must be sealed from the atmosphere because of the alkali metal reactants and hydrolytic degradation of molten salt electrolytes.

  19. Metals processing control by counting molten metal droplets

    DOEpatents

    Schlienger, Eric; Robertson, Joanna M.; Melgaard, David; Shelmidine, Gregory J.; Van Den Avyle, James A.

    2000-01-01

    Apparatus and method for controlling metals processing (e.g., ESR) by melting a metal ingot and counting molten metal droplets during melting. An approximate amount of metal in each droplet is determined, and a melt rate is computed therefrom. Impedance of the melting circuit is monitored, such as by calculating by root mean square a voltage and current of the circuit and dividing the calculated current into the calculated voltage. Analysis of the impedance signal is performed to look for a trace characteristic of formation of a molten metal droplet, such as by examining skew rate, curvature, or a higher moment.

  20. ADVANCED CERAMIC COMPOSITES FOR MOLTEN ALUMINUM CONTACT APPLICATIONS

    SciTech Connect

    Hemrick, James Gordon; Peters, Klaus-Markus

    2009-01-01

    A new refractory material which was developed for use in molten aluminum contact applications was shown to exhibit improved corrosion and wear resistance leading to improved thermal management through reduced heat losses caused by refractory thinning and wastage. This material was developed based on an understanding of the corrosion and wear mechanisms associated with currently used aluminum contact refractories under a U.S. Department of Energy funded project to investigate multifunctional refractory materials for energy efficient handling of molten metals. This new material has been validated through an industrial trial at a commercial aluminum rod and cable mill. Material development and results of this industrial validation trial are discussed.

  1. Fabrication of catalytic electrodes for molten carbonate fuel cells

    DOEpatents

    Smith, James L.

    1988-01-01

    A porous layer of catalyst material suitable for use as an electrode in a molten carbonate fuel cell includes elongated pores substantially extending across the layer thickness. The catalyst layer is prepared by depositing particulate catalyst material into polymeric flocking on a substrate surface by a procedure such as tape casting. The loaded substrate is heated in a series of steps with rising temperatures to set the tape, thermally decompose the substrate with flocking and sinter bond the catalyst particles into a porous catalytic layer with elongated pores across its thickness. Employed as an electrode, the elongated pores provide distribution of reactant gas into contact with catalyst particles wetted by molten electrolyte.

  2. Porous electrolyte retainer for molten carbonate fuel cell. [lithium aluminate

    DOEpatents

    Singh, R.N.; Dusek, J.T.

    1979-12-27

    A porous tile for retaining molten electrolyte within a fuel cell is prepared by sintering particles of lithium aluminate into a stable structure. The tile is assembled between two porous metal plates which serve as electrodes with fuels gases such as H/sub 2/ and CO opposite to oxidant gases such as O/sub 2/ and CO/sub 2/. The tile is prepared with a porosity of 55 to 65% and a pore size distribution selected to permit release of sufficient molten electrolyte to wet but not to flood the adjacent electrodes.

  3. Porous electrolyte retainer for molten carbonate fuel cell

    DOEpatents

    Singh, Raj N.; Dusek, Joseph T.

    1983-06-21

    A porous tile for retaining molten electrolyte within a fuel cell is prepared by sintering particles of lithium aluminate into a stable structure. The tile is assembled between two porous metal plates which serve as electrodes with fuels gases such as H.sub.2 and CO opposite to oxidant gases such as O.sub.2 and CO.sub.2. The tile is prepared with a porosity of 55-65% and a pore size distribution selected to permit release of sufficient molten electrolyte to wet but not to flood the adjacent electrodes.

  4. Corrosion of SiC by Molten Salt

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Smialek, James L.

    1987-01-01

    Advanced ceramic materials considered for wide range of applications as in gas turbine engines and heat exchangers. In such applications, materials may be in corrosive environments that include molten salts. Very corrosive to alloys. In order to determine extent of problem for ceramic materials, corrosion of SiC by molten salts studied in both jet fuel burners and laboratory furnaces. Surface of silicon carbide corroded by exposure to flame seeded with 4 parts per million of sodium. Strength of silicon carbide decreased by corrosion in flame and tube-furnace tests.

  5. Spectroscopic characterization of nanohydroxyapatite synthesized by molten salt method.

    PubMed

    Gopi, D; Indira, J; Kavitha, L; Kannan, S; Ferreira, J M F

    2010-10-01

    Hydroxyapatite (HAP) nanopowders were synthesized by molten salt method at 260 degrees C. The as-prepared powders were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). With the aid of the obtained results the effect of calcining time on the crystallinity, size and morphology of HAP nanopowders is presented. The HAP nanopowders synthesized by molten salt method consist of pure phase of HAP without any impurities and showed the rod-like morphology without detectable decomposition up to 1100 degrees C.

  6. High-temperature molten-salt thermal electrochemical cell

    SciTech Connect

    Plichta, E.J.; Behl, W.K.

    1990-02-12

    This invention relates in general to a high temperature molten salt thermal electrochemical cell and in particular to such a cell including cobalt oxide (Co{sub 3}O{sub 4}) as the cathode material. High temperature molten salt thermal electrochemical cells are widely used as power sources for projectiles, rockets, bombs, mines, missiles, decoys, jammers and torpedoes. These are also used as fuses. Thermal electrochemical cells are reserve-type cells that can be activated by heating with a pyrotechnic heat source such as zirconium and barium chromate powders or mixtures of iron powder and potassium perchlorate.

  7. Cytotoxic glucosphingolipid from Celtis Africana

    PubMed Central

    Perveen, Shagufta; Al-Taweel, Areej Mohammad; Fawzy, Ghada Ahmed; El-Shafae, Azza Muhammed; Khan, Afsar; Proksch, Peter

    2015-01-01

    Background: Literature survey proved the use of the powdered sun-dried bark and roots of Celtis africana for the treatment of cancer in South Africa. Objective: The aim of this study was to do further isolation work on the ethyl acetate fraction and to investigate the cytotoxic activities of the various fractions and isolated compound. Materials and Methods: Cytotoxicity of petroleum ether, chloroform, ethyl acetate, n-butanol fractions and compound 1 were tested on mouse lymphoma cell line L5178Y using the microculture tetrazolium assay. Results: One new glucosphingolipid 1 was isolated from the aerial parts of C. africana. The structure of the new compound was determined by extensive analysis by one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy and mass spectrometry. The ethyl acetate fraction and compound 1 showed strong cytotoxic activity with an EC50 value of 8.3 μg/mL and 7.8 μg/mL, respectively, compared with Kahalalide F positive control (6.3 μg/mL). Conclusion: This is the first report of the occurrence of a cytotoxic glucosphingolipid in family Ulmaceae. PMID:26109753

  8. Molten metal containment vessel with rare earth oxysulfide protective coating thereon and method of making same

    DOEpatents

    Krikorian, Oscar H.; Curtis, Paul G.

    1992-01-01

    An improved molten metal containment vessel is disclosed in which wetting of the vessel's inner wall surfaces by molten metal is inhibited by coating at least the inner surfaces of the containment vessel with one or more rare earth oxysulfide or rare earth sulfide compounds to inhibit wetting and or adherence by the molten metal to the surfaces of the containment vessel.

  9. Saponins as cytotoxic agents: a review

    PubMed Central

    Galanty, Agnieszka; Sobolewska, Danuta

    2010-01-01

    Saponins are natural glycosides which possess a wide range of pharmacological properties including cytotoxic activity. In this review, the recent studies (2005–2009) concerning the cytotoxic activity of saponins have been summarized. The correlations between the structure and the cytotoxicity of both steroid and triterpenoid saponins have been described as well as the most common mechanisms of action. PMID:20835386

  10. Oxygen electrode reaction in molten carbonate fuel cells

    SciTech Connect

    Appleby, A.J.; White, R.E.

    1992-07-07

    Molten carbonate fuel cell system is a leading candidate for the utility power generation because of its high efficiency for fuel to AC power conversion, capability for an internal reforming, and a very low environmental impact. However, the performance of the molten carbonate fuel cell is limited by the oxygen reduction reaction and the cell life time is limited by the stability of the cathode material. An elucidation of oxygen reduction reaction in molten alkali carbonate is essential because overpotential losses in the molten carbonate fuel cell are considerably greater at the oxygen cathode than at the fuel anode. Oxygen reduction on a fully-immersed gold electrode in a lithium carbonate melt was investigated by electrochemical impedance spectroscopy and cyclic voltammetry to determine electrode kinetic and mass transfer parameters. The dependences of electrode kinetic and mass transfer parameters on gas composition and temperature were examined to determine the reaction orders and the activation energies. The results showed that oxygen reduction in a pure lithium carbonate melt occurs via the peroxide mechanism. A mass transfer parameter, D{sub O}{sup 1/2}C{sub O}, estimated by the cyclic voltammetry concurred with that calculated by the EIS technique. The temperature dependence of the exchange current density and the product D{sub O}{sup 1/2}C{sub O} were examined and the apparent activation energies were determined to be about 122 and 175 kJ/ mol, respectively.

  11. MOLTEN METAL FROM ELECTRIC MELTING FURNACE IS TRANSFERRED THROUGH RUNNER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    MOLTEN METAL FROM ELECTRIC MELTING FURNACE IS TRANSFERRED THROUGH RUNNER BOX TO HOLDING FURNACE PRIOR TO POURING. VIEW FROM BEHIND "NORTH STATION" IN CAST SHOP. THE RUNNER BOX MUST BE HEATED PRIOR TO THE TRANSFER. - American Brass Foundry, 70 Sayre Street, Buffalo, Erie County, NY

  12. 19. MOLTEN IRON FLOWS INTO A 'BOTTLE' AT FURNACE NO. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. MOLTEN IRON FLOWS INTO A 'BOTTLE' AT FURNACE NO. 1. THE IRON WILL BE TRANSPORTED BY RAIL TO THE OPEN HEARTH OR BASIC OXYGEN FURNACES, WHERE IT IS A MAJOR COMPONENT IN THE PRODUCTION OF STEEL. - Corrigan, McKinney Steel Company, 3100 East Forty-fifth Street, Cleveland, Cuyahoga County, OH

  13. Alloys compatibility in molten salt fluorides: Kurchatov Institute related experience

    NASA Astrophysics Data System (ADS)

    Ignatiev, Victor; Surenkov, Alexandr

    2013-10-01

    In the last several years, there has been an increased interest in the use of high-temperature molten salt fluorides in nuclear power systems. For all molten salt reactor designs, materials selection is a very important issue. This paper summarizes results, which led to selection of materials for molten salt reactors in Russia. Operating experience with corrosion thermal convection loops has demonstrated good capability of the “nickel-molybdenum alloys + fluoride salt fueled by UF4 and PuF3 + cover gas” system up to 750 °C. A brief description is given of the container material work in progress. Tellurium corrosion of Ni-based alloys in stressed and unloaded conditions studies was also tested in different molten salt mixtures at temperatures up to 700-750 °C, also with measurement of the redox potential. HN80MTY alloy with 1% added Al is the most resistant to tellurium intergranular cracking of Ni-base alloys under study.

  14. Structural change in molten basalt at deep mantle conditions.

    PubMed

    Sanloup, Chrystèle; Drewitt, James W E; Konôpková, Zuzana; Dalladay-Simpson, Philip; Morton, Donna M; Rai, Nachiketa; van Westrenen, Wim; Morgenroth, Wolfgang

    2013-11-01

    Silicate liquids play a key part at all stages of deep Earth evolution, ranging from core and crust formation billions of years ago to present-day volcanic activity. Quantitative models of these processes require knowledge of the structural changes and compression mechanisms that take place in liquid silicates at the high pressures and temperatures in the Earth's interior. However, obtaining such knowledge has long been impeded by the challenging nature of the experiments. In recent years, structural and density information for silica glass was obtained at record pressures of up to 100 GPa (ref. 1), a major step towards obtaining data on the molten state. Here we report the structure of molten basalt up to 60 GPa by means of in situ X-ray diffraction. The coordination of silicon increases from four under ambient conditions to six at 35 GPa, similar to what has been reported in silica glass. The compressibility of the melt after the completion of the coordination change is lower than at lower pressure, implying that only a high-order equation of state can accurately describe the density evolution of silicate melts over the pressure range of the whole mantle. The transition pressure coincides with a marked change in the pressure-evolution of nickel partitioning between molten iron and molten silicates, indicating that melt compressibility controls siderophile-element partitioning.

  15. Impact of corrosion test container material in molten fluorides

    SciTech Connect

    Olson, Luke C.; Fuentes, Roderick E.; Martinez-Rodriguez, Michael J.; Ambrosek, James W.; Sridharan, Kumar; Anderson, Mark H.; Garcia-Diaz, Brenda L.; Gray, Joshua; Allen, Todd R.

    2015-10-15

    The effects of crucible material choice on alloy corrosion rates in immersion tests in molten LiF–NaF–KF (46.5–11.5-42 mol. %) salt held at 850 °C for 500 hrs are described. Four crucible materials were studied. Molten salt exposures of Incoloy-800H in graphite, Ni, Incoloy-800H, and pyrolytic boron nitride (PyBN) crucibles all led to weight-loss in the Incoloy-800H coupons. Alloy weight loss was ~30 times higher in the graphite and Ni crucibles in comparison to the Incoloy-800H and PyBN crucibles. It is hypothesized galvanic coupling between the alloy coupons and crucible materials contributed to the higher corrosion rates. Alloy salt immersion in graphite and Ni crucibles had similar weight-loss hypothesized to occur due to the rate limiting out diffusion of Cr in the alloys to the surface where it reacts with and dissolves into the molten salt, followed by the reduction of Cr from solution at the molten salt and graphite/Ni interfaces. As a result, both the graphite and the Ni crucibles provided sinks for the Cr, in the formation of a Ni–Cr alloy in the case of the Ni crucible, and Cr carbide in the case of the graphite crucible.

  16. Study of an F center in molten KCl

    SciTech Connect

    Parrinello, M.; Rahman, A.

    1983-05-01

    It is shown that a discretized version of Feynman's path integral provides a convenient tool for the numerical investigation of the properties of an electron solvated in molten KCl. The binding energy and the pair correlation functions are calculated. The local structure around the solute electron appears to be different from that of an F center in the solid.

  17. Research and development issues for molten carbonate fuel cells

    SciTech Connect

    Krumpelt, M.

    1996-04-01

    This paper describes issues pertaining to the development of molten carbonate fuel cells. In particular, the corrosion resistance and service life of nickel oxide cathodes is described. The resistivity of lithium oxide/iron oxides and improvement with doping is addressed.

  18. Impact of corrosion test container material in molten fluorides

    DOE PAGES

    Olson, Luke C.; Fuentes, Roderick E.; Martinez-Rodriguez, Michael J.; Ambrosek, James W.; Sridharan, Kumar; Anderson, Mark H.; Garcia-Diaz, Brenda L.; Gray, Joshua; Allen, Todd R.

    2015-10-15

    The effects of crucible material choice on alloy corrosion rates in immersion tests in molten LiF–NaF–KF (46.5–11.5-42 mol. %) salt held at 850 °C for 500 hrs are described. Four crucible materials were studied. Molten salt exposures of Incoloy-800H in graphite, Ni, Incoloy-800H, and pyrolytic boron nitride (PyBN) crucibles all led to weight-loss in the Incoloy-800H coupons. Alloy weight loss was ~30 times higher in the graphite and Ni crucibles in comparison to the Incoloy-800H and PyBN crucibles. It is hypothesized galvanic coupling between the alloy coupons and crucible materials contributed to the higher corrosion rates. Alloy salt immersion inmore » graphite and Ni crucibles had similar weight-loss hypothesized to occur due to the rate limiting out diffusion of Cr in the alloys to the surface where it reacts with and dissolves into the molten salt, followed by the reduction of Cr from solution at the molten salt and graphite/Ni interfaces. As a result, both the graphite and the Ni crucibles provided sinks for the Cr, in the formation of a Ni–Cr alloy in the case of the Ni crucible, and Cr carbide in the case of the graphite crucible.« less

  19. 30 CFR 57.16013 - Working with molten metal.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Working with molten metal. 57.16013 Section 57.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES...

  20. 30 CFR 57.16013 - Working with molten metal.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Working with molten metal. 57.16013 Section 57.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES...

  1. 30 CFR 56.16013 - Working with molten metal.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Working with molten metal. 56.16013 Section 56.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Materials...

  2. 30 CFR 56.16013 - Working with molten metal.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Working with molten metal. 56.16013 Section 56.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Materials...

  3. 30 CFR 57.16013 - Working with molten metal.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Working with molten metal. 57.16013 Section 57.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES...

  4. 30 CFR 56.16013 - Working with molten metal.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Working with molten metal. 56.16013 Section 56.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Materials...

  5. 30 CFR 56.16013 - Working with molten metal.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Working with molten metal. 56.16013 Section 56.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Materials...

  6. 30 CFR 57.16013 - Working with molten metal.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Working with molten metal. 57.16013 Section 57.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES...

  7. 30 CFR 56.16013 - Working with molten metal.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Working with molten metal. 56.16013 Section 56.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Materials...

  8. 30 CFR 57.16013 - Working with molten metal.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Working with molten metal. 57.16013 Section 57.16013 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES...

  9. [Bio-oil production from biomass pyrolysis in molten salt].

    PubMed

    Ji, Dengxiang; Cai, Tengyue; Ai, Ning; Yu, Fengwen; Jiang, Hongtao; Ji, Jianbing

    2011-03-01

    In order to investigate the effects of pyrolysis conditions on bio-oil production from biomass in molten salt, experiments of biomass pyrolysis were carried out in a self-designed reactor in which the molten salt ZnCl2-KCl (with mole ratio 7/6) was selected as heat carrier, catalyst and dispersion agent. The effects of metal salt added into ZnCl2-KCl and biomass material on biomass pyrolysis were discussed, and the main compositions of bio-oil were determined by GC-MS. Metal salt added into molten salt could affect pyrolysis production yields remarkably. Lanthanon salt could enhance bio-oil yield and decrease water content in bio-oil, when mole fraction of 5.0% LaCl3 was added, bio-oil yield could reach up to 32.0%, and water content of bio-oil could reduce to 61.5%. The bio-oil and char yields were higher when rice straw was pyrolysed, while gas yield was higher when rice husk was used. Metal salts showed great selectivity on compositions of bio-oil. LiCl and FeCl2 promoted biomass to pyrolyse into smaller molecular weight compounds. CrCl3, CaCl2 and LaCl3 could restrain second pyrolysis of bio-oil. The research provided a scientific reference for production of bio-oil from biomass pyrolysis in molten salt.

  10. Production of oxygen from lunar soil by molten salt electrolysis

    NASA Technical Reports Server (NTRS)

    Keller, Rudolf

    1989-01-01

    A simple approach to utilizing lunar resources proposes to dissolve lunar soil, without or with little beneficiation, in a suitable molten salt and to electrolyze the oxides to oxygen and a metal byproduct. The envisioned process and the required technological advances are discussed. Promising electrolysis conditions have been identified in a recent experimental program to manufacture silicon and aluminum from anorthite.

  11. Two techniques enable sampling of filtered and unfiltered molten metals

    NASA Technical Reports Server (NTRS)

    Burris, L., Jr.; Pierce, R. D.; Tobias, K. R.; Winsch, I. O.

    1967-01-01

    Filtered samples of molten metals are obtained by filtering through a plug of porous material fitted in the end of a sample tube, and unfiltered samples are obtained by using a capillary-tube extension rod with a perforated bucket. With these methods there are no sampling errors or loss of liquid.

  12. Hydrated multivalent cations are new class of molten salt mixtures

    NASA Technical Reports Server (NTRS)

    Angell, C. A.

    1967-01-01

    Electrical conductance and activation energy measurements on mixtures of calcium and potassium nitrate show the hydrated form to be a new class of molten salt. The theoretical glass transition temperature of the hydrate varied in a manner opposite to that of the anhydrous system.

  13. Chemical Safety: Molten Salt Baths Cited as Lab Hazards.

    ERIC Educational Resources Information Center

    Baum, Rudy

    1982-01-01

    Discusses danger of explosions with molten salts baths, commonly used as heat-transfer media. One such explosion involved use of a bath containing 3-lb sodium nitrite and 1-lb potassium thiocyanate. Although most commercially available mixtures for heat transfer contain oxidizers, a reducer (thiocyanate) was included which possibly triggered the…

  14. Oxygen from the lunar soil by molten silicate electrolysis

    NASA Technical Reports Server (NTRS)

    Colson, Russell O.; Haskin, Larry A.

    1992-01-01

    Accepting that oxygen, rather than gigantic gems or gold, is likely to make the Moon's Klondike, the extraction of oxygen from the lunar soil by molten silicate electrolysis has chosen to be investigated. Process theory and proposed lunar factory are addressed.

  15. Molten metal feed system controlled with a traveling magnetic field

    DOEpatents

    Praeg, Walter F.

    1991-01-01

    A continuous metal casting system in which the feed of molten metal is controlled by means of a linear induction motor capable of producing a magnetic traveling wave in a duct that connects a reservoir of molten metal to a caster. The linear induction motor produces a traveling magnetic wave in the duct in opposition to the pressure exerted by the head of molten metal in the reservoir so that p.sub.c =p.sub.g -p.sub.m where p.sub.c is the desired pressure in the caster, p.sub.g is the gravitational pressure in the duct exerted by the force of the head of molten metal in the reservoir, and p.sub.m is the electromagnetic pressure exerted by the force of the magnetic field traveling wave produced by the linear induction motor. The invention also includes feedback loops to the linear induction motor to control the casting pressure in response to measured characteristics of the metal being cast.

  16. Sulfur tolerant molten carbonate fuel cell anode and process

    DOEpatents

    Remick, Robert J.

    1990-01-01

    Molten carbonate fuel cell anodes incorporating a sulfur tolerant carbon monoxide to hydrogen water-gas-shift catalyst provide in situ conversion of carbon monoxide to hydrogen for improved fuel cell operation using fuel gas mixtures of over about 10 volume percent carbon monoxide and up to about 10 ppm hydrogen sulfide.

  17. Henry's Law Activity of Oxygen in Molten Iron

    NASA Astrophysics Data System (ADS)

    Matousek, J. W.

    2015-09-01

    A model is proposed for the solubility of oxygen in molten iron in dilute solutions in which the oxygen exists in two states, free and associated. Only the free oxygen has thermodynamic activity in the sense of interaction with an electrochemical cell to produce the voltage described by the Nernst equation.

  18. INTERIOR VIEW OF IRON TREATMENT (DESULPHURIZATION) AREA. MOLTEN IRON PROCEEDS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW OF IRON TREATMENT (DESULPHURIZATION) AREA. MOLTEN IRON PROCEEDS FROM CUPOLA TO IRON TREATMENT AREAS BEFORE BEING TRANSFERRED TO PIPE CASTING MACHINES. - United States Pipe & Foundry Company Plant, Melting & Treatment Areas, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  19. Liquid surface skimmer apparatus for molten lithium and method

    DOEpatents

    Robinson, Samuel C.; Pollard, Roy E.; Thompson, William F.; Stark, Marshall W.; Currin, Jr., Robert T.

    1995-01-01

    This invention relates to an apparatus for separating two fluids having different specific gravities. The invention also relates to a method for using the separating apparatus of the present invention. This invention particularly relates to the skimming of molten lithium metal from the surface of a fused salt electrolyte in the electrolytic production of lithium metal from a mixed fused salt.

  20. Nuclear performance optimization of the molten-salt fusion breeder

    SciTech Connect

    Lee, J.D.; Bandini, B.R.

    1986-06-05

    Improved nuclear analysis, including the treatment of resonance and spatial self-shielding, coupled with an optimization procedure, has resulted in an improved performance estimate for the molten salt blanket. Net U-233 breeding ratio ranges between 0.58 and 0.63, and blanket energy multiplication ranges between 1.8 and 1.9.

  1. Treatment of plutonium process residues by molten salt oxidation

    SciTech Connect

    Stimmel, J.; Wishau, R.; Ramsey, K.B.; Montoya, A.; Brock, J.; Heslop, M.; Wernly, K.

    1999-04-01

    Molten Salt Oxidation (MSO) is a thermal process that can remove more than 99.999% of the organic matrix from combustible {sup 238}Pu material. Plutonium processing residues are injected into a molten salt bed with an excess of air. The salt (sodium carbonate) functions as a catalyst for the conversion of the organic material to carbon dioxide and water. Reactive species such as fluorine, chlorine, bromine, iodine, sulfur, phosphorous and arsenic in the organic waste react with the molten salt to form the corresponding neutralized salts, NaF, NaCl, NaBr, NaI, Na{sub 2}SO{sub 4}, Na{sub 3}PO{sub 4} and NaAsO{sub 2} or Na{sub 3}AsO4. Plutonium and other metals react with the molten salt and air to form metal salts or oxides. Saturated salt will be recycled and aqueous chemical separation will be used to recover the {sup 238}Pu. The Los Alamos National Laboratory system, which is currently in the conceptual design stage, will be scaled down from current systems for use inside a glovebox.

  2. 9. VIEW OF MOLTEN SALT BATH EQUIPMENT AND ROLLER PRESSES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. VIEW OF MOLTEN SALT BATH EQUIPMENT AND ROLLER PRESSES BEING INSTALLED ON THE WEST SIDE (SIDE B) OF BUILDING 883. SIDE B OF BUILDING 883 WAS USED TO PROCESS ENRICHED URANIUM FROM 1957-66. (1/23/57) - Rocky Flats Plant, Uranium Rolling & Forming Operations, Southeast section of plant, southeast quadrant of intersection of Central Avenue & Eighth Street, Golden, Jefferson County, CO

  3. 13. VIEW OF THE MOLTEN SALT BATHS USED TO UNIFORMLY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. VIEW OF THE MOLTEN SALT BATHS USED TO UNIFORMLY AND QUICKLY HEAT METALS PRIOR TO WORKING (ROLLING). (9/16/85) - Rocky Flats Plant, Uranium Rolling & Forming Operations, Southeast section of plant, southeast quadrant of intersection of Central Avenue & Eighth Street, Golden, Jefferson County, CO

  4. Molten-Salt-Based Growth of Group III Nitrides

    DOEpatents

    Waldrip, Karen E.; Tsao, Jeffrey Y.; Kerley, Thomas M.

    2008-10-14

    A method for growing Group III nitride materials using a molten halide salt as a solvent to solubilize the Group-III ions and nitride ions that react to form the Group III nitride material. The concentration of at least one of the nitride ion or Group III cation is determined by electrochemical generation of the ions.

  5. Conduit for high temperature transfer of molten semiconductor crystalline material

    NASA Technical Reports Server (NTRS)

    Fiegl, George (Inventor); Torbet, Walter (Inventor)

    1983-01-01

    A conduit for high temperature transfer of molten semiconductor crystalline material consists of a composite structure incorporating a quartz transfer tube as the innermost member, with an outer thermally insulating layer designed to serve the dual purposes of minimizing heat losses from the quartz tube and maintaining mechanical strength and rigidity of the conduit at the elevated temperatures encountered. The composite structure ensures that the molten semiconductor material only comes in contact with a material (quartz) with which it is compatible, while the outer layer structure reinforces the quartz tube, which becomes somewhat soft at molten semiconductor temperatures. To further aid in preventing cooling of the molten semiconductor, a distributed, electric resistance heater is in contact with the surface of the quartz tube over most of its length. The quartz tube has short end portions which extend through the surface of the semiconductor melt and which are lef bare of the thermal insulation. The heater is designed to provide an increased heat input per unit area in the region adjacent these end portions.

  6. Milk fat globule membrane isolated from buttermilk or whey cream and their lipid components inhibit infectivity of rotavirus in vitro.

    PubMed

    Fuller, K L; Kuhlenschmidt, T B; Kuhlenschmidt, M S; Jiménez-Flores, R; Donovan, S M

    2013-06-01

    Milk fat is encapsulated in a milk fat globule membrane (MFGM) that contains bioactive glycoproteins and glycolipids. The MFGM inhibits infectivity of rotavirus (RV), activity that has been attributed to its glycoprotein and carbohydrate components. However, previous studies of proteins and oligosaccharides in the MGFM have not accounted for all the bioactivity associated with the complete MFGM. The lipid fraction of the MFGM accounts for half of its composition by weight, and we postulate that this fraction should be tested by itself to determine if it plays a role in antiviral activity. Herein, the anti-RV activity of an organic extract of MFGM was tested. Natural and whey buttermilk powders containing bovine MFGM enriched in polar lipids were prepared by microfiltration and supercritical fluid extraction treatment to reduce the triglyceride content of the powders. Lipid fractions were then extracted from the MFGM using both single- and dual-phase extraction methods. Whole MFGM and organic extracts were screened in MA-104 cells for anti-infective activity against a neuraminidase-sensitive rotavirus using a focus-forming unit assay. Dose-dependent inhibition was observed for whole buttermilk and cheese whey MFGM against the rotavirus. In general, buttermilk MFGM exhibited greater RV percentage inhibition than cheese whey MFGM. Organic-soluble anti-RV compounds were identified in bovine MFGM. The most active fraction, isolated by dual-phase extraction and iatrobead chromatography, was free of proteins and highly nonpolar. Further separation of this fraction in a less polar solvent (30:1 chloroform:methanol) resolved at least 5 lipid-containing compounds, which likely contribute to the anti-RV activity associated with bovine MFGM. In summary, lipid components associated with MFGM appear to contribute in large part to the anti-RV activity associated with the bovine MFGM.

  7. Force-induced globule-coil transition in laminin binding protein and its role for viral-cell membrane fusion.

    PubMed

    Zaitsev, Boris N; Benedetti, Fabrizio; Mikhaylov, Andrey G; Korneev, Denis V; Sekatskii, Sergey K; Karakouz, Tanya; Belavin, Pavel A; Netesova, Nina A; Protopopova, Elena V; Konovalova, Svetlana N; Dietler, Giovanni; Loktev, Valery B

    2014-12-01

    The specific interactions of the pairs laminin binding protein (LBP)-purified tick-borne encephalitis viral surface protein E and certain recombinant fragments of this protein, as well as West Nile viral surface protein E and certain recombinant fragments of that protein, are studied by combined methods of single-molecule dynamic force spectroscopy (SMDFS), enzyme immunoassay and optical surface waves-based biosensor measurements. The experiments were performed at neutral pH (7.4) and acid pH (5.3) conditions. The data obtained confirm the role of LBP as a cell receptor for two typical viral species of the Flavivirus genus. A comparison of these data with similar data obtained for another cell receptor of this family, namely human αVβ3 integrin, reveals that both these receptors are very important. Studying the specific interaction between the cell receptors in question and specially prepared monoclonal antibodies against them, we could show that both interaction sites involved in the process of virus-cell interaction remain intact at pH 5.3. At the same time, for these acid conditions characteristic for an endosome during flavivirus-cell membrane fusion, SMDFS data reveal the existence of a force-induced (effective already for forces as small as 30-70 pN) sharp globule-coil transition for LBP and LBP-fragments of protein E complexes. We argue that this conformational transformation, being an analog of abrupt first-order phase transition and having similarity with the famous Rayleigh hydrodynamic instability, might be indispensable for the flavivirus-cell membrane fusion process. PMID:25319621

  8. Milk fat globule glycoproteins in human milk and in gastric aspirates of mother's milk-fed preterm infants.

    PubMed

    Peterson, J A; Hamosh, M; Scallan, C D; Ceriani, R L; Henderson, T R; Mehta, N R; Armand, M; Hamosh, P

    1998-10-01

    Human milk fat globule (HMFG) glycoproteins can prevent infections by microorganisms in breast-fed infants; the MUC-1 mucin inhibits binding of S-fimbriated Escherichia coli to buccal mucosa, and lactadherin may prevent symptomatic rotavirus infections. In this study, the survival of these HMFG glycoproteins in the stomach of human milk-fed preterm infants (gestational age = 27.5 +/- 0.4 wk) was assessed, and levels in their mothers' milk determined, using specific RIAs. Butyrophilin, a major component of HMFG membrane that has no demonstrated antimicrobial activity, was studied for comparison. The levels of mucin, lactadherin, and butyrophilin in 41 milk samples of 20 mothers were 729 +/- 75, 93 +/- 10, and 41 +/- 3 microg/mL, respectively. Mucin and lactadherin were significantly higher in early milk samples (<15 d postpartum) than in later milk samples (15-90 d postpartum), whereas butyrophilin showed no such difference. Significant amounts of mucin and lactadherin were found in almost all gastric aspirates of human milk-fed infants, even 4 h after feeding (mucin, 270 +/- 30 microg/mL; lactadherin, 23.2 +/- 4.4 microg/mL), whereas butyrophilin was rapidly degraded in the majority of aspirates. Western blot analysis demonstrated that the immunoreactive mucin, lactadherin, and butyrophilin in the milk-fed gastric aspirates had the expected native molecular weights. Mucin and lactadherin survived at all gastric pH values, whereas butyrophilin was found only at pH > 4. Neither lactadherin nor butyrophilin were detected in gastric aspirates of formula-fed infants (gestational age = 27.8 +/- 0.5 wk), whereas the very low level of mucin (9.1 +/- 1.1 microg/mL) in this group is presumably cross-reacting gastric mucin. These results demonstrate that two HMFG glycoproteins implicated in prevention of infection, MUC-1 mucin and lactadherin, survive and maintain their integrity in the stomachs of human milk-fed preterm infants.

  9. MUC-1 expression in pleomorphic adenomas using two human milk fat globule protein membrane antibodies (HMFG-1 and HMFG-2)

    PubMed Central

    PONCE-BRAVO, Santa; LEDESMA-MONTES, Constantino; GARCÉS-ORTÍZ, Maricela

    2015-01-01

    Pleomorphic adenoma (PA) is the most common salivary gland tumor and its microscopic features and histogenesis are a matter of debate. Human milk fat globule protein membrane (HMFG) monoclonal antibodies (MoAbs) comprise a set of antibodies against the mucin 1 (MUC-1) protein detected in several salivary gland tumors. Objective The aim of this study was to assess the immunoexpression of the PA neoplastic cells to MUC-1 protein using HMFG-1 and HMFG-2 MoAbs, contrasting these results with those from normal salivary gland tissue. Material and Methods Immunohistochemical detection of MUC-1 protein using HMFG-1 and HMFG-2 MoAbs was made in 5 mm thick, paraffin embedded slides, and the avidin-biotin method was used. Results Positivity to HMFG-1 and HMFG-2 MoAbs was found in ductal, squamous metaplastic and neoplastic myoepithelial cells, keratin pearls and intraductal mucous material. Two kinds of myoepithelial cells were identified: classic myoepithelial cells around ducts were negative to both MoAbs, and modified myoepithelial cells were positive to both MoAbs. This last cellular group of the analyzed tumors showed similar MUC-1 immunoexpression to ductal epithelial cells using both HMFG antibodies. Intraductal mucous secretion was also HMFG-1 and HMFG-2 positive. Conclusions Our results showed there are two kinds of myoepithelial cells in PA. The first cellular group is represented by the different kinds of neoplastic myoepithelial cells and is HMFG-positive. The second one is HMFG-negative and represented by the neoplastic myoepithelial cells located around the ducts. PMID:26221920

  10. Corrosion Behavior of Alloys in Molten Fluoride Salts

    NASA Astrophysics Data System (ADS)

    Zheng, Guiqiu

    The molten fluoride salt-cooled high-temperature nuclear reactor (FHR) has been proposed as a candidate Generation IV nuclear reactor. This reactor combines the latest nuclear technology with the use of molten fluoride salt as coolant to significantly enhance safety and efficiency. However, an important challenge in FHR development is the corrosion of structural materials in high-temperature molten fluoride salt. The structural alloys' degradation, particularly in terms of chromium depletion, and the molten salt chemistry are key factors that impact the lifetime of nuclear reactors and the development of future FHR designs. In support of materials development for the FHR, the nickel base alloy of Hastelloy N and iron-chromium base alloy 316 stainless steel are being actively considered as critical structural alloys. Enriched 27LiF-BeF2 (named as FLiBe) is a promising coolant for the FHR because of its neutronic properties and heat transfer characteristics while operating at atmospheric pressure. In this study, the corrosion behavior of Ni-5Cr and Ni-20Cr binary model alloys, and Hastelloy N and 316 stainless steel in molten FLiBe with and without graphite were investigated through various microstructural analyses. Based on the understanding of the corrosion behavior and data of above four alloys in molten FLiBe, a long-term corrosion prediction model has been developed that is applicable specifically for these four materials in FLiBe at 700ºC. The model uses Cr concentration profile C(x, t) as a function of corrosion distance in the materials and duration fundamentally derived from the Fick's diffusion laws. This model was validated with reasonable accuracy for the four alloys by fitting the calculated profiles with experimental data and can be applied to evaluate corrosion attack depth over the long-term. The critical constant of the overall diffusion coefficient (Deff) in this model can be quickly calculated from the experimental measurement of alloys' weight

  11. Fundamental study of molten pool depth measurement method using an ultrasonic phased array system

    NASA Astrophysics Data System (ADS)

    Mizota, Hirohisa; Nagashima, Yoshiaki; Obana, Takeshi

    2015-07-01

    The molten pool depth measurement method using an ultrasonic phased array system has been developed. The molten pool depth distribution is evaluated by comparing the times taken by the ultrasonic wave to propagate through a molten pool and a solid-phase and through only the solid-phase near the molten pool. Maximum molten pool depths on a flat type-304 stainless-steel plate, formed with a gas tungsten arc welding machine for different welding currents from 70 to 150 A, were derived within an error of ±0.5 mm.

  12. Validation studies of a computational model for molten material freezing

    SciTech Connect

    Sawada, Tetsuo; Ninokata, Hisashi; Shimizu, Akinao

    1996-02-01

    Validation studies are described of a computational model for the freezing of molten core materials under core disruptive accident conditions of fast breeder reactors. A series of out-of-pile experiments named SIMBATH, performed at Forschungszentrum Karlsruhe in Germany, has already been analyzed with the SIMMER-II code. In the current study, TRAN simulation tests in the SIMBATH facility are analyzed by SIMMER-II for its modeling validation of molten material freezing. The original TRAN experiments were performed at Sandia National laboratories to examine the freezing behavior of molten UO{sub 2} injected into an annular channels. In the TAN simulation experiments of the SIMBATH series, similar freezing phenomena are investigated for molten thermite, a mixture of Al{sub 2}O{sub 3} and iron, instead of UO{sub 2}. Two typical TRAN simulation tests are analyzed that aim at clarification of the applicability of the code to the freezing process during the experiments. The distribution of molten materials that are deposited in the test section according to the experimental measurements and in calculations by SIMMER-II is compared. These studies confirm that the conduction-limited freezing model combined with the rudimentary bulk freezing (particle-jamming) model of SIMMER-II is compared. These studies confirm that the conduction-limited freezing model combined with the rudimentary bulk freezing (particle-jamming) model of SIMMER-II could be used to reproduce the TRAN simulation experiments satisfactorily. This finding encourages the extrapolation of the results of previous validation research for SIMMER-II based on other SIMBATH tests to reactor case analyses. The calculation by SIMMER-II suggest that further improvements of the model, such as freezing on a convex surface of pin cladding and the scraping of crusts, make possible more accurate simulation of freezing phenomena.

  13. Casting Apparatus Including A Gas Driven Molten Metal Injector And Method

    DOEpatents

    Meyer, Thomas N.

    2004-06-01

    The casting apparatus (50) includes a holding vessel (10) for containing a supply of molten metal (12) and a casting mold (52) located above the holding vessel (10) and having a casting cavity (54). A molten metal injector (14) extends into the holding vessel (10) and is at least partially immersed in the molten metal (12) in the holding vessel (10). The molten metal injector (14) is in fluid communication with the casting cavity (54). The molten metal injector (14) has an injector body (16) defining an inlet opening (24) for receiving molten metal into the injector body (16). A gas pressurization source (38) is in fluid communication with the injector body (16) for cyclically pressurizing the injector body (16) and inducing molten metal to flow from the injector body (16) to the casting cavity (54). An inlet valve (42) is located in the inlet opening (24) in the injector body (16) for filling molten metal into the injector body (16). The inlet valve (42) is configured to prevent outflow of molten metal from the injector body (16) during pressurization and permit inflow of molten metal into the injector body (16) after pressurization. The inlet valve (42) has an inlet valve actuator (44) located above the surface of the supply of molten metal (12) and is operatively connected to the inlet valve (42) for operating the inlet valve (42) between open and closed positions.

  14. Cytotoxic prenylflavonoids from Artocarpus elasticus.

    PubMed

    Ko, Horng-Huey; Lu, Yi-Huang; Yang, Sheng-Zehn; Won, Shen-Jeu; Lin, Chun-Nan

    2005-11-01

    Five new prenylated flavonoids, artelastoheterol (1), artelasticinol (2), cycloartelastoxanthone (3), artelastoxanthone (4), and cycloartelastoxanthendiol (5), along with five known compounds, were isolated from the root bark of Artocarpus elasticus. The structures of 1-5 were elucidated by spectroscopic methods and through comparison with data reported in the literature. The previously known compound artonol A (6) exhibited cytotoxic activity against the A549 human cancer cell line, with an ED50 value of 1.1 microg/mL.

  15. Comparative cytotoxicity of periodontal bacteria

    SciTech Connect

    Stevens, R.H.; Hammond, B.F.

    1988-11-01

    The direct cytotoxicity of sonic extracts (SE) from nine periodontal bacteria for human gingival fibroblasts (HGF) was compared. Equivalent dosages (in terms of protein concentration) of SE were used to challenge HGF cultures. The cytotoxic potential of each SE was assessed by its ability to (1) inhibit HGF proliferation, as measured by direct cell counts; (2) inhibit 3H-thymidine incorporation in HGF cultures; or (3) cause morphological alterations of the cells in challenged cultures. The highest concentration (500 micrograms SE protein/ml) of any of the SEs used to challenge the cells was found to be markedly inhibitory to the HGFs by all three of the criteria of cytotoxicity. At the lowest dosage tested (50 micrograms SE protein/ml); only SE from Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, and Fusobacterium nucleatum caused a significant effect (greater than 90% inhibition or overt morphological abnormalities) in the HGFs as determined by any of the criteria employed. SE from Capnocytophaga sputigena, Eikenella corrodens, or Wolinella recta also inhibited cell proliferation and thymidine incorporation at this dosage; however, the degree of inhibition (5-50%) was consistently, clearly less than that of the first group of three organisms named above. The SE of the three other organisms tested (Actinomyces odontolyticus, Bacteroides intermedius, and Streptococcus sanguis) had little or no effect (0-10% inhibition) at this concentration. The data suggest that the outcome of the interaction between bacterial components and normal resident cells of the periodontium is, at least in part, a function of the bacterial species.

  16. Characteristics of ovine cytotoxic lymphocytes

    SciTech Connect

    Knisley, K.A.

    1987-01-01

    Experiments were conducted to examine characteristics of the effector cells responsible for cell-mediated cytotoxicity in the sheep. Conditions for the production and assay of ovine T cell growth factor (TCGF) activity were evaluated. Peripheral blood leukocytes (PBL) were stimulated with concanavalin A (Con A) in the presence of 2% autologous serum or serum-free media. A 28 h proliferation assay with 2.5 x 10/sup 4/ h Con A blasts per well was optimal for detection of TCGF. Peak TCGF activity occurred with a 30-37kD molecular weight fraction. Ovine PBL were used for in vitro generation of genetically-restricted cytotoxic T lymphocytes (CTL). Peripheral blood leukocytes from sheep that had been previously inoculated with live vaccinia virus were stimulated by being cultured in vitro on glutaraldehyde-fixed vaccinia-infected autologous skin fibroblasts. Cytotoxic T lymphocyte activity was assessed in a 6 h /sup 51/Cr-release assay on autologous and allogeneic fibroblasts targets. Killing was restricted to virus-infected autologous targets. In vitro generation of both anti-vaccinia and anti-TNP CTL activity could be enhanced by the addition of TCGF containing media from ConA-stimulated PBL.

  17. Biochemical and histological characterization of antigens preferentially expressed on the surface and cytoplasm of breast carcinoma cells identified by monoclonal antibodies against the human milk fat globule.

    PubMed

    Peterson, J A; Zava, D T; Duwe, A K; Blank, E W; Battifora, H; Ceriani, R L

    1990-06-01

    The preparation of monoclonal antibodies (MAbs) against the human milk fat globule membrane with preferential binding to breast carcinoma cells is described. Using BALB/c mouse myeloma cells; inter-specific, intra-strain, and inter-strain hybridomas were isolated that identified three different components of the human milk fat globule of approximately 46,000, and 70,000 daltons and a mucin-like glycoprotein complex (NPGP) ranging from 400,000 to over a million daltons, respectively. Three MAbs (BrE1, BrE2, BrE3) identified the latter component which consists of at least three different size molecules for which the aforementioned MAb's have different binding specificities. MAbs, BrE2 and BrE3, bound to normal breast epithelial cells but to a lesser extent than to tumors and only at the apical surface facing the lumen, while they bound breast carcinomas strongly, and often in the cytoplasm as well as on the surface. Higher concentrations of BrE3 were required to stain normal breast compared to breast tumors. BrE1 also stained breast carcinomas both on the surface and cytoplasmically but did not stain normal breast tissue. The MAb, Mc13, as well as the previously reported MAb McR2, both against the 70,000 dalton component, did not significantly stain either normal or cancerous breast tissue in histological sections but did bind significantly to cultured breast epithelial cells and to the milk fat globule membrane. The MAbs, Mc8 and Mc3, reported previously to be against the 46,000 dalton component, stained histologically only malignant breast tissue but only weakly; however, they bound strongly to intact breast carcinoma cells and breast cell membrane preparations with a radioimmunobinding assay. These MAbs should be useful in characterizing the surface of breast epithelial cells, studying surface alterations in malignancy, and possibly in breast cancer diagnosis and therapy.

  18. Molten Salts for High Temperature Reactors: University of Wisconsin Molten Salt Corrosion and Flow Loop Experiments -- Issues Identified and Path Forward

    SciTech Connect

    Piyush Sabharwall; Matt Ebner; Manohar Sohal; Phil Sharpe; Thermal Hydraulics Group

    2010-03-01

    Considerable amount of work is going on regarding the development of high temperature liquid salts technology to meet future process needs of Next Generation Nuclear Plant. This report identifies the important characteristics and concerns of high temperature molten salts (with lesson learned at University of Wisconsin-Madison, Molten Salt Program) and provides some possible recommendation for future work

  19. MAG-GATE System for Molten metal Flow Control

    SciTech Connect

    Richard D. Nathenson, P.E.

    2004-05-15

    The need for improved active flow control has been recognized as part of the Steel Industry Technology Roadmap. Under TRP 9808 for the American Iron and Steel Institute and the Department of Energy, Concept Engineering Group Inc. has developed MAG-GATE{trademark}, an electromagnetic system for active molten metal flow control. Two hot steel tests were successfully conducted in 2003 at the Whemco Foundry Division, Midland, PA. Approximately 110,000 pounds of 0.2% carbon steel were poured through the device subject to electromagnetic flow control. Excellent agreement between predicted and actual flow control was found. A survey of the molten metal flow control practices at 100 continuous casters in North America was also conducted in 2003. This report summarizes the results of the development program to date. Preliminary designs are described for the next step of a beta test at an operating billet/bloom or slab caster.

  20. Steam methane reforming in molten carbonate salt. Final report

    SciTech Connect

    Erickson, D.C.

    1996-05-01

    This report documents the work accomplished on the project {open_quotes}Steam Methane Reforming in Molten Carbonate Salt.{close_quotes}. This effort has established the conceptual basis for molten carbonate-based steam reforming of methane. It has not proceeded to prototype verification, because corrosion concerns have led to reluctance on the part of large hydrogen producers to adopt the technology. Therefore the focus was shifted to a less corrosive embodiment of the same technology. After considerable development effort it was discovered that a European company (Catalysts and Chemicals Europe) was developing a similar process ({open_quotes}Regate{close_quotes}). Accordingly the focus was shifted a second time, to develop an improvement which is generic to both types of reforming. That work is still in progress, and shows substantial promise.

  1. Solids concentration measurements in molten wax by an ultrasonic technique

    SciTech Connect

    Soong, Y.; Gamwo, I.K.; Blackwell, A.G.; Schehl, R.R.; Zarochak, M.F.

    1994-12-31

    The application of the three-phase slurry reactor system to coal liquefaction processing and chemical industries has recently received considerable attention. To design and efficiently operate a three-phase slurry reactor, the degree of dispersion of the solid (catalyst) in the reactor should be understood. The solids distribution within the reactor greatly affects its performance. An ultrasonic technique is under development for measuring solids concentration in a three-phase slurry reactor. Preliminary measurements have been made on slurries consisting of molten paraffin wax, glass beads, and nitrogen bubbles at 189 C. The data show that the velocity and attenuation of the sound are well-defined functions of the solid and gas concentrations in the molten wax.

  2. Electromagnetic valve for controlling the flow of molten, magnetic material

    DOEpatents

    Richter, T.

    1998-06-16

    An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell. 5 figs.

  3. Electromagnetic valve for controlling the flow of molten, magnetic material

    DOEpatents

    Richter, Tomas

    1998-01-01

    An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell.

  4. Laser Acoustic Molten Metal Depth Sensing in Titanium

    SciTech Connect

    J. B. Walter; K. L. Telschow; R. E. Haun

    1999-09-22

    A noncontacting ultrasonic method has been investigated for probing the solidification front in molten titanium for the purposes of profiling the channel depth in a plasma hearth re-melter. The method, known as Laser Ultrasonics, utilized a pulsed laser for generation of ultrasonic waves at the surface of a molten metal pool. The ultrasonic waves propagated into the liquid titanium reflected from the solidification front and the boundaries of the solid plug. A Fabry-Perot interferometer, driven by a second laser, demodulated the small displacements caused by the ultrasonic wave motion at the liquid surface. The method and results of measurements taken within a small research plasma melting furnace will be described. Successful results were obtained even directly beneath the plasma arc using this all-optical approach.

  5. Burning molten metallic spheres: One class of ball lightning?

    NASA Astrophysics Data System (ADS)

    Stephan, Karl D.; Massey, Nathan

    2008-08-01

    Abrahamson and Dinniss [2000. Ball lightning caused by oxidation of nanoparticle networks from normal lightning strikes on soil. Nature 403, 519-521] proposed a theory of ball lighting in which silicon nanoparticles undergo slow oxidation and emit light. Paiva et al. [2007. Production of ball-lightning-like luminous balls by electrical discharges in silicon. Physical Review Letters 98, 048501] reported that an electric arc to silicon produced long-lasting luminous white spheres showing many characteristics of ball lightning. We show experimentally that these consist of burning molten silicon spheres with diameters in the 0.1-1 mm range. The evidence of our experiments leads us to propose that a subset of ball lightning events may consist of macro-scale molten spheres of burning metallic materials likely to be ejected from a conventional lightning strike to earth.

  6. Review of literature surface tension data for molten silicon

    NASA Technical Reports Server (NTRS)

    Hardy, S.

    1981-01-01

    Measurements of the surface tension of molten silicon are reported. For marangoni flow, the important parameter is the variation of surface tension with temperature, not the absolute value of the surface tension. It is not possible to calculate temperature coefficients using surface tension measurements from different experiments because the systematic errors are usually larger than the changes in surface tension because of temperature variations. The lack of good surface tension data for liquid silicon is probably due to its extreme chemical reactivity. A material which resists attack by molten silicon is not found. It is suggested that all of the sessile drip surface tension measurements are probably for silicon which is contaminated by the substrate materials.

  7. Plasma-sprayed ceramic coatings for protection against molten metal.

    SciTech Connect

    Hollis, K. J.; Peters, M. I.; Bartram, B. D.

    2002-01-01

    Molten metal environments pose a special demand on materials due to the high temperature corrosion effects and thermal expansion mismatch induced stress effects. A solution that has been successfully employed is the use of a base material for the mechanical strength and a coating material for the chemical compatibility with the molten metal. The work described here used such an approach coating tungsten rods with aluminum oxide, yttria-stabilized zirconia, yttrium oxide, and erbium oxide deposited by atmospheric plasma spraying. The ceramic materials were deposited under varying conditions to produce different structures. Measurement of particle characteristics was performed to correlate to material properties. The coatings were tested in a thermal cycling environment to simulate the metal melting cycle expected in service. Results of the testing indicate the effect of material composition and spray conditions on the thermal cycle crack resistance of the coatings.

  8. A facile molten-salt route to graphene synthesis.

    PubMed

    Liu, Xiaofeng; Giordano, Cristina; Antonietti, Markus

    2014-01-15

    Efficient synthetic routes are continuously pursued for graphene in order to implement its applications in different areas. However, direct conversion of simple monomers to graphene through polymerization in a scalable manner remains a major challenge for chemists. Herein, a molten-salt (MS) route for the synthesis of carbon nanostructures and graphene by controlled carbonization of glucose in molten metal chloride is reported. In this process, carbohydrate undergoes polymerization in the presence of strongly interacting ionic species, which leads to nanoporous carbon with amorphous nature and adjustable pore size. At a low precursor concentration, the process converts the sugar molecules (glucose) to rather pure few-layer graphenes. The MS-derived graphenes are strongly hydrophobic and exhibit remarkable selectivity and capacity for absorption of organics. The methodology described may open up a new avenue towards the synthesis and manipulation of carbon materials in liquid media.

  9. Electrochemical Synthesis of Magnesium Hexaboride by Molten Salt Technique.

    PubMed

    Angappan, S; Kalaiselvi, N; Sudha, R; Visuvasam, A

    2014-01-01

    The present work reports electrochemical synthesis of MgB6 from molten salts using the precursor consists of LiF-B2O3-MgCl2. An attempt has been made to synthesize metastable phase MgB6 crystal by electrolysis method. DTA/TGA studies were made to determine the eutectic point of the melt and it was found to be around 900°C. The electrolysis was performed at 900°C under argon atmosphere, at current density of 1.5 A/cm(2). The electrodeposited crystals were examined using XRD, SEM, and XPS. From the above studies, the electrochemical synthesis method for hypothetical MgB6 from chloro-oxy-fluoride molten salt system is provided. Mechanism for the formation of magnesium hexaboride is discussed.

  10. Uranium (III) precipitation in molten chloride by wet argon sparging

    NASA Astrophysics Data System (ADS)

    Vigier, Jean-François; Laplace, Annabelle; Renard, Catherine; Miguirditchian, Manuel; Abraham, Francis

    2016-06-01

    In the context of pyrochemical processes for nuclear fuel treatment, the precipitation of uranium (III) in molten salt LiCl-CaCl2 (30-70 mol%) at 705 °C is studied. First, this molten chloride is characterized with the determination of the water dissociation constant. With a value of 10-4.0, the salt has oxoacid properties. Then, the uranium (III) precipitation using wet argon sparging is studied. The salt is prepared using UCl3 precursor. At the end of the precipitation, the salt is totally free of solubilized uranium. The main part is converted into UO2 powder but some uranium is lost during the process due to the volatility of uranium chloride. The main impurity of the resulting powder is calcium. The consequences of oxidative and reductive conditions on precipitation are studied. Finally, coprecipitation of uranium (III) and neodymium (III) is studied, showing a higher sensitivity of uranium (III) than neodymium (III) to precipitation.

  11. Lithium-ferrate-based cathodes for molten carbonate fuel cells

    SciTech Connect

    Lanagan, M.T.; Wolfenstine, J.; Bloom, I.; Kaun, T.D.; Krumpelt, M.

    1996-12-31

    Argonne National Laboratory is developing advanced cathodes for pressurized operation of the molten carbonate fuel cell (MCFC) at approximately 650 degrees Centigrade. These cathodes are based on lithium ferrate (LiFeO[sub 2]) which is attractive because of its very low solubility in the molten (Li,K)[sub 2]CO[sub 3] electrolyte. Because of its high resistivity, LiFeO[sub 2] cannot be used as a direct substitute for NiO. Cation substitution is, therefore, necessary to decrease resistivity. The effect of cation substitution on the resistivity and deformation of LiFeO[sub 2] was determined. The substitutes were chosen because their respective oxides as well as LiFeO[sub 2] crystallize with the rock-salt structure.

  12. Micro encapsulation in situ with super permeating molten wax

    SciTech Connect

    Carter, E.

    2007-07-01

    A new class of grout material based on molten wax offers a dramatic improvement in permeation grouting performance. This new material makes a perfect in situ containment of buried radioactive waste both feasible and cost effective. This paper describes various ways the material can be used to isolate buried waste in situ. Potential applications described in the paper include buried radioactive waste in deep trenches, deep shafts, Infiltration trenches, and large buried objects. Use of molten wax for retrieval of waste is also discussed. Wax can also be used for retrieval of air sensitive materials or drummed waste. This paper provides an analysis of the methods of application and the expected performance and cost of several potential projects. (authors)

  13. Laser Acoustic Molten Metal Depth Sensing in Titanium

    SciTech Connect

    Walter, John Bradley; Telschow, Kenneth Louis; Haun, R.E.

    1999-08-01

    A noncontacting ultrasonic method has been investigated for probing the solidification front in molten titanium for the purposes of profiling the channel depth in plasma hearth re-melter. The method, known as Laser Ultrasonics, utilized a pulsed laser for generation of ultrasonic waves at the surface of a molten metal pool. The ultrasonic waves propagated into the liquid titanium reflected from the solidification front and the boundaries of the solid plug. A Fabry-Perot interferometer, driven by a second laser, demodulated the small displacements caused by the ultrasonic wave motion at the liquid surface. The method and results of measurements taken within a small research plasma melting furnace will be described. Successful results were obtained even directly beneath the plasma arc using this all optical approach.

  14. Electrochemical Synthesis of Magnesium Hexaboride by Molten Salt Technique

    PubMed Central

    Angappan, S.; Kalaiselvi, N.; Sudha, R.; Visuvasam, A.

    2014-01-01

    The present work reports electrochemical synthesis of MgB6 from molten salts using the precursor consists of LiF–B2O3–MgCl2. An attempt has been made to synthesize metastable phase MgB6 crystal by electrolysis method. DTA/TGA studies were made to determine the eutectic point of the melt and it was found to be around 900°C. The electrolysis was performed at 900°C under argon atmosphere, at current density of 1.5 A/cm2. The electrodeposited crystals were examined using XRD, SEM, and XPS. From the above studies, the electrochemical synthesis method for hypothetical MgB6 from chloro-oxy-fluoride molten salt system is provided. Mechanism for the formation of magnesium hexaboride is discussed. PMID:27350961

  15. Development of molten carbonate fuel cell power plant, volume 1

    NASA Astrophysics Data System (ADS)

    1985-03-01

    The technical results of a molten carbonate fuel cell power plant evelopment program are presented which establish the necessary technology base and demonstrate readiness to proceed with the fabrication and test of full size prototype stacks for coal fueled molten carbonate fuel cell power plants. The effort covered power plant systems studies, fuel cell component technology development, fuel cell stack design and analysis, manufacturing process definition, and an extensive experimental program. The reported results include: the definition and projected costs for a reference coal fueled power plant system based on user requirements, state-of-the-art advances in anode and electrolyte matrix technology, the detailed description of an internally manifolded stack design concept offering a number of attractive advantages, and the specification of the fabrication processes and methods necessary to produce and assemble this design. Results from the experimental program are documented.

  16. Molten salt reactors for burning dismantled weapons fuel

    SciTech Connect

    Gat, U.; Engel, J.R. ); Dodds, H.L. . Dept. of Nuclear Engineering)

    1992-12-01

    In this paper, the molten salt reactor (MSR) option for burning fissile fuel form dismantled weapons is examined. It is concluded that MSRs are potentially suitable for beneficial utilization of the dismantled fuel. the MSRs have the flexibility to utilize any fissile fuel in continuous operation with no special modifications, as demonstrated in the Molten Salt Reactor Experiment, while maintaining their economy. The MSRs further require a minimum of special fuel preparation and can tolerate denaturing and dilution of the fuel. Fuel shipments can be arbitrarily small, which may reduce the risk of diversion. The MSRs have inherent safety features that make them acceptable and attractive. They can burn a fuel type completely and convert it to other fuels. The MSRs also have the potential for burning the actinides and delivering the waste in an optimal form, thus contributing to the solution of one of the major remaining problems for deployment o nuclear power.

  17. Molten salt treatment to minimize and optimize waste

    SciTech Connect

    Gat, U.; Crosley, S.M.; Gay, R.L.

    1993-07-01

    A combination molten salt oxidizer (MSO) and molten salt reactor (MSR) is described for treatment of waste. The MSO is proposed for contained oxidization of organic hazardous waste, for reduction of mass and volume of dilute waste by evaporation of the water. The NTSO residue is to be treated to optimize the waste in terms of its composition, chemical form, mixture, concentration, encapsulation, shape, size, and configuration. Accumulations and storage are minimized, shipments are sized for low risk. Actinides, fissile material, and long-lived isotopes are separated and completely burned or transmuted in an MSR. The MSR requires no fuel element fabrication, accepts the materials as salts in arbitrarily small quantities enhancing safety, security, and overall acceptability.

  18. Hydrocracking of coal using molten salts as catalysts

    NASA Astrophysics Data System (ADS)

    Kikkawa, S.; Nomura, M.; Sakashita, H.; Nishimura, M.; Miyake, M.

    1981-10-01

    Characteristics of the reactions during coal liquefaction and the hydrocracking of coal and coal-related materials using ZnCl2-transition metal chloride or ZnCl2-alkaline metal chloride are discussed. The studies involve development of a molten salt catalyst for hydrocracking heavy residual oils or coals, including hydrocarbons containing many heteroatoms. It was found that ZnCl2 shows higher activity for hydrocracking of anthracene and phenanthrene, and experiments with Yubari coal using the binary metal catalysts ZnCl2-MoCl5 and ZnCl2-CrCl3 are described. The use of molten salts in the desulphurization of heavy residual oils is also explored, specifically for the hydrocracking of benziophene, and the possibility that a coal-like polymer structure containing an oxygen surplus might depolymerize above ternary melts is suggested.

  19. Nuclear Hybrid Energy Systems: Molten Salt Energy Storage

    SciTech Connect

    P. Sabharwall; M. Green; S.J. Yoon; S.M. Bragg-Sitton; C. Stoots

    2014-07-01

    With growing concerns in the production of reliable energy sources, the next generation in reliable power generation, hybrid energy systems, are being developed to stabilize these growing energy needs. The hybrid energy system incorporates multiple inputs and multiple outputs. The vitality and efficiency of these systems resides in the energy storage application. Energy storage is necessary for grid stabilizing and storing the overproduction of energy to meet peak demands of energy at the time of need. With high thermal energy production of the primary nuclear heat generation source, molten salt energy storage is an intriguing option because of its distinct properties. This paper will discuss the different energy storage options with the criteria for efficient energy storage set forth, and will primarily focus on different molten salt energy storage system options through a thermodynamic analysis

  20. Report on large scale molten core/magnesia interaction test

    SciTech Connect

    Chu, T.Y.; Bentz, J.H.; Arellano, F.E.; Brockmann, J.E.; Field, M.E.; Fish, J.D.

    1984-08-01

    A molten core/material interaction experiment was performed at the Large-Scale Melt Facility at Sandia National Laboratories. The experiment involved the release of 230 kg of core melt, heated to 2923/sup 0/K, into a magnesia brick crucible. Descriptions of the facility, the melting technology, as well as results of the experiment, are presented. Preliminary evaluations of the results indicate that magnesia brick can be a suitable material for core ladle construction.

  1. Thermal and physical properties of molten fluorides for nuclear applications

    NASA Astrophysics Data System (ADS)

    van der Meer, J. P. M.; Konings, R. J. M.

    2007-01-01

    LiF-BeF 2-ThF 4 is a key system in molten salt reactor fuel studies. In this paper we give an overview of some important features of this ternary system. We discuss the phase behavior, vapor pressure, density and viscosity, based on what is known in the literature and on our own data from previous work on the thermodynamic assessment of LiF-BeF 2-ThF 4.

  2. Fission product ion exchange between zeolite and a molten salt

    NASA Astrophysics Data System (ADS)

    Gougar, Mary Lou D.

    The electrometallurgical treatment of spent nuclear fuel (SNF) has been developed at Argonne National Laboratory (ANL) and has been demonstrated through processing the sodium-bonded SNF from the Experimental Breeder Reactor-II in Idaho. In this process, components of the SNF, including U and species more chemically active than U, are oxidized into a bath of lithium-potassium chloride (LiCl-KCl) eutectic molten salt. Uranium is removed from the salt solution by electrochemical reduction. The noble metals and inactive fission products from the SNF remain as solids and are melted into a metal waste form after removal from the molten salt bath. The remaining salt solution contains most of the fission products and transuranic elements from the SNF. One technique that has been identified for removing these fission products and extending the usable life of the molten salt is ion exchange with zeolite A. A model has been developed and tested for its ability to describe the ion exchange of fission product species between zeolite A and a molten salt bath used for pyroprocessing of spent nuclear fuel. The model assumes (1) a system at equilibrium, (2) immobilization of species from the process salt solution via both ion exchange and occlusion in the zeolite cage structure, and (3) chemical independence of the process salt species. The first assumption simplifies the description of this physical system by eliminating the complications of including time-dependent variables. An equilibrium state between species concentrations in the two exchange phases is a common basis for ion exchange models found in the literature. Assumption two is non-simplifying with respect to the mathematical expression of the model. Two Langmuir-like fractional terms (one for each mode of immobilization) compose each equation describing each salt species. The third assumption offers great simplification over more traditional ion exchange modeling, in which interaction of solvent species with each other

  3. METHOD OF PROTECTING TANTALUM CRUCIBLES AGAINST REACTION WITH MOLTEN URANIUM

    DOEpatents

    Feder, H.M.; Chellew, N.R.

    1960-08-16

    Tantalum crucibles against reaction with molten uranium by contacting the surfaces to be protected with metallic boron (as powder, vapor, or suspension in a liquid-volatilenonreacting medium, such as acetone and petroleum oil) at about 1800 deg C in vacuum, discontinuing contact with the boron, and heating the crucibles to a temperature of between 1800 aad 2000 deg C, whereby the tantalum boride formed in the first heating step is converted to tantalum monoboride.

  4. Molten carbonate fuel cell cathode with mixed oxide coating

    DOEpatents

    Hilmi, Abdelkader; Yuh, Chao-Yi

    2013-05-07

    A molten carbonate fuel cell cathode having a cathode body and a coating of a mixed oxygen ion conductor materials. The mixed oxygen ion conductor materials are formed from ceria or doped ceria, such as gadolinium doped ceria or yttrium doped ceria. The coating is deposited on the cathode body using a sol-gel process, which utilizes as precursors organometallic compounds, organic and inorganic salts, hydroxides or alkoxides and which uses as the solvent water, organic solvent or a mixture of same.

  5. DFT Study of Oxygen Dissociation in Molten Carbonate.

    PubMed

    Lei, Xueling; Haines, Kahla; Huang, Kevin; Qin, Changyong

    2015-08-20

    Using density functional theory method, we have studied the oxygen dissociation in alkali molten carbonate at the B3LYP/6-31G(d) level. The calculated energies were then verified by MP4 and CCSD(T). A four-formula cluster (M2CO3)4, M = Li, Na, and K was used to describe the molten carbonate. It was found that the adsorption of oxygen to molten carbonate is of a chemical type and leads to the formation of CO5(2-) in MC, which was confirmed for the first time by DFT calculations. The energy barrier for its dissociation is calculated to be 197.9, 116.7, and 170.3 kJ/mol in the (M2CO3)4 cluster, M = Li, Na, and K, respectively. If the reaction of O2 + 2CO3(2-) → 2CO4(2-) is approximated as a one-step reaction, the activation energy is estimated to be 96.2, 15.1, and 68.6 kJ/mol, respectively. The reaction rate is first order to the pressure of oxygen. Surprisingly, the reaction of oxygen dissociation has the lowest energy barrier in sodium carbonate, which is consistent with the recent experimental findings. It is very clear that the molten carbonate salt has directly participated in the ORR process and plays an important role as a catalyst in the cathode of SOFCs. The oxygen reduction has been facilitated by MC and enhanced cell performance has been observed.

  6. The viscosity and electrical conductivity of single molten salts

    NASA Astrophysics Data System (ADS)

    Marcus, Yizhak

    2016-08-01

    In addition to the well-established Arrhenius-type temperature-dependence of the specific and molar conductivities of molten salts, it turns out that they also depend linearly on the molar volumes, in analogy with the behavior of their fluidities. Similar values of the molar volumes representing the immobilization of the ions result from both kinds of flow phenomena. However, the activation energy for the fluidity is some five times larger than for the conductivity.

  7. Molten carbonate fuel cell reduction of nickel deposits

    DOEpatents

    Smith, James L.; Zwick, Stanley A.

    1987-01-01

    A molten carbonate fuel cell with anode and cathode electrodes and an eleolyte formed with two tile sections, one of the tile sections being adjacent the anode and limiting leakage of fuel gas into the electrolyte with the second tile section being adjacent the cathode and having pores sized to permit the presence of oxygen gas in the electrolyte thereby limiting the formation of metal deposits caused by the reduction of metal compositions migrating into the electrolyte from the cathode.

  8. Non-segregating electrolytes for molten carbonate fuel cells

    SciTech Connect

    Krumpelt, M.; Kaun, T.; Lanagan, M.

    1996-08-01

    Current MCFCs use a Li/K carbonate mixture; the segregation increases the K concentration near the cathode, leading to increase cathode solubility and performance decline. ANL is developing molten carbonates that have minimal segregation; the approach is using Li-Na carbonates. In screening tests, fully developed potential distributions were obtained for 4 Li/Na compositions, and performance data were used to compare these.

  9. High current density cathode for electrorefining in molten electrolyte

    DOEpatents

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  10. Development of large scale internal reforming molten carbonate fuel cell

    SciTech Connect

    Sasaki, A.; Shinoki, T.; Matsumura, M.

    1996-12-31

    Internal Reforming (IR) is a prominent scheme for Molten Carbonate Fuel Cell (MCFC) power generating systems in order to get high efficiency i.e. 55-60% as based on the Higher Heating Value (HHV) and compact configuration. The Advanced Internal Reforming (AIR) technology has been developed based on two types of the IR-MCFC technology i.e. Direct Internal Reforming (DIR) and Indirect Internal Reforming (DIR).

  11. Cytotoxic quassinoids from Simaba cedron.

    PubMed

    Ozeki, A; Hitotsuyanagi, Y; Hashimoto, E; Itokawa, H; Takeya, K; de Mello Alves, S

    1998-06-26

    Four new quassinoids, cedronolactones A-D (1-4), together with nine known compounds, simalikalactone D (5), chaparrinone (6), chaparrin (7), glaucarubolone (8), glaucarubol (9), samaderine Z (10), guanepolide (11), ailanquassin A (12), and polyandrol (13), were isolated from the wood of Simaba cedron. The chemical structures of 1-4 were elucidated on the basis of their chemical and spectral properties. Cedronolactone A (1) was shown to exhibit a significant in vitro cytotoxicity (IC50 0.0074 microg/mL) against P-388 cells.

  12. Electromagnetic confinement for vertical casting or containing molten metal

    DOEpatents

    Lari, Robert J.; Praeg, Walter F.; Turner, Larry R.

    1991-01-01

    An apparatus and method adapted to confine a molten metal to a region by means of an alternating electromagnetic field. As adapted for use in the present invention, the alternating electromagnetic field given by B.sub.y =(2.mu..sub.o .rho.gy).sup.1/2 (where B.sub.y is the vertical component of the magnetic field generated by the magnet at the boundary of the region; y is the distance measured downward form the top of the region, .rho. is the metal density, g is the acceleration of gravity and .mu..sub.o is the permeability of free space) induces eddy currents in the molten metal which interact with the magnetic field to retain the molten metal with a vertical boudnary. As applied to an apparatus for the continuous casting of metal sheets or rods, metal in liquid form can be continuously introduced into the region defined by the magnetic field, solidified and conveyed away from the magnetic field in solid form in a continuous process.

  13. Design of a helium-cooled molten salt fusion breeder

    SciTech Connect

    Moir, R.W.; Lee, J.D.; Fulton, F.J.; Huegel, F.; Neef, W.S. Jr.; Sherwood, A.E.; Berwald, D.H.; Whitley, R.H.; Wong, C.P.C.; DeVan, J.H.

    1985-02-01

    A new conceptual blanket design for a fusion reactor produces fissile material for fission power plants. Fission is suppressed by using beryllium, rather than uranium, to multiply neutrons and also by minimizing the fissile inventory. The molten-salt breeding media (LiF + BeF/sub 2/ + TghF/sub 4/) is circulated through the blanket and on to the online processing system where /sup 233/U and tritium are continuously removed. Helium cools the blanket including the steel pipes containing the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion rate by molten salt. We estimate the breeder, having 3000 MW of fusion power, produces 6400 kg of /sup 233/U per year, which is enough to provide make up for 20 GWe of LWR per year (or 14 LWR plants of 4440 MWt) or twice that many HTGRs or CANDUs. Safety is enhanced because the afterheat is low and the blanket materials do not react with air or water. The fusion breeder based on a pre-MARS tandem mirror is estimated to cost $4.9B or 2.35 times an LWR of the same power. The estimated present value cost of the /sup 2/anumber/sup 3/U produced is $40/g if utility financed or $16/g if government financed.

  14. Pipe Poiseuille flow of viscously anisotropic, partially molten rock

    NASA Astrophysics Data System (ADS)

    Allwright, Jane; Katz, Richard F.

    2014-12-01

    Laboratory experiments in which synthetic, partially molten rock is subjected to forced deformation provide a context for testing hypotheses about the dynamics and rheology of the mantle. Here our hypothesis is that the aggregate viscosity of partially molten mantle is anisotropic, and that this anisotropy arises from deviatoric stresses in the rock matrix. We formulate a model of pipe Poiseuille flow based on theory by Takei & Holtzman and Takei & Katz. Pipe Poiseuille is a configuration that is accessible to laboratory experimentation but for which there are no published results. We analyse the model system through linearized analysis and numerical simulations. This analysis predicts two modes of melt segregation: migration of melt from the centre of the pipe towards the wall and localization of melt into high-porosity bands that emerge near the wall, at a low angle to the shear plane. We compare our results to those of Takei & Katz for plane Poiseuille flow; we also describe a new approximation of radially varying anisotropy that improves the self-consistency of models over those of Takei & Katz. This study provides a set of baseline, quantitative predictions to compare with future laboratory experiments on forced pipe Poiseuille flow of partially molten mantle.

  15. Experimental investigation of molten metal freezing on to a structure

    SciTech Connect

    Mizanur Rahman, M.; Hino, Tomohiko; Morita, Koji; Matsumoto, Tatsuya; Nakagawa, Kiyoshi; Fukuda, Kenji; Maschek, Werner

    2007-10-15

    During core disruptive accidents (CDAs) of Liquid Metal Reactors (LMRs), it is important to understand the freezing phenomena of molten metal, which may prevent fuel dispersal and subsequent shutdown. The present paper describes the freezing behavior of molten metal during interaction with a structure with a view to the safety of LMRs. In this study, Wood's metal (melting point 78.8 C) was used as a simulant melt, while stainless steel and copper were used as freezing structures. A series of simulation experiments was conducted to study the freezing behavior of Wood's metal during pouring on to the freezing structures immersed in a coolant. In the experiments, simulant melt was poured into a stainless steel tube and finally ejected into a coolant through a nozzle so as to observe the freezing behavior of the molten metal. The penetration length and width were measured in the air cooled experiments, whereas penetration length and the proportion of adhering frozen metal were measured in water coolant experiment. The melt flow and distribution were observed in both types of experiment using a high-speed video camera. Distinct freezing modes were observed in the water coolant experiments, whereas only one freezing mode with a longer melt penetration was found in air coolant experiments. The present result will be utilized to create a relevant database for the verification of reactor safety analysis codes. (author)

  16. Advances in electroanalysis, sensing and monitoring in molten salts.

    PubMed

    Corrigan, Damion K; Elliott, Justin P; Blair, Ewen O; Reeves, Simon J; Schmüser, Ilka; Walton, Anthony J; Mount, Andrew R

    2016-08-15

    Microelectrodes have a number of advantages over macroelectrodes for quantitative electroanalysis and monitoring, including reduced iR drop, a high signal-to-noise ratio and reduced sensitivity to convection. Their use in molten salts has been generally precluded by the combined materials challenges of stresses associated with thermal cycling and physical and corrosive chemical degradation at the relatively high temperatures involved. We have shown that microfabrication, employing high precision photolithographic patterning in combination with the controlled deposition of materials, can be used to successfully address these challenges. The resulting molten salt compatible microelectrodes (MSMs) enable prolonged quantitative microelectrode measurements in molten salts (MSs). This paper reports the fabrication of novel MSM disc electrodes, chosen because they have an established ambient analytical response. It includes a detailed set of electrochemical characterisation studies which demonstrate both their enhanced capability over macroelectrodes and over commercial glass pulled microelectrodes, and their ability to extract quantitative electroanalytical information from MS systems. MSM measurements are then used to demonstrate their potential for shedding new light on the fundamental properties of, and processes in, MSs, such as mass transport, charge transfer reaction rates and the selective plating/stripping and alloying reactions of liquid Bi and other metals; this will underpin the development of enhanced MS industrial processes, including pyrochemical spent nuclear fuel reprocessing.

  17. Design of a helium-cooled molten salt fusion breeder

    NASA Astrophysics Data System (ADS)

    Moir, R. W.; Lee, J. D.; Fulton, F. J.; Huegel, F.; Neef, W. S., Jr.; Sherwood, A. E.; Berwald, D. H.; Whitley, R. H.; Wong, C. P. C.; Devan, J. H.

    1985-02-01

    A new conceptual blanket design for a fusion reactor is discussed which produces fissile material for fission power plants. Fission is suppressed by using beryllium, rather than uranium, to multiply neutrons and also by minimizing the fissile inventory. The molten-salt breeding media (LiF + BeF2 + TghF4) is circulated through the blanket and on to the online processing system where (233)U and tritium are continuously removed. Helium cools the blanket including the steel pipes containing the molten salt. Austenitic steel was chosen because of its ease of fabrication, adequate radiation-damage lifetime, and low corrosion rate by molten salt. Safety is enhanced because the afterheat is low and the blanket materials do not react with air or water. The fusion breeder based on a pre-MARS mirror is estimated to cost $4.9B or 2.35 time an LWR of the same power. The estimated present value cost of the (233)U produced is $40/g if utility financed or $16/g if government financed.

  18. Molten salt processing of mixed wastes with offgas condensation

    SciTech Connect

    Cooper, J.F.; Brummond, W.; Celeste, J.; Farmer, J.; Hoenig, C.; Krikorian, O.H.; Upadhye, R. ); Gay, R.L.; Stewart, A.; Yosim, S. . Energy Systems Group)

    1991-05-13

    We are developing an advanced process for treatment of mixed wastes in molten salt media at temperatures of 700--1000{degrees}C. Waste destruction has been demonstrated in a single stage oxidation process, with destruction efficiencies above 99.9999% for many waste categories. The molten salt provides a heat transfer medium, prevents thermal surges, and functions as an in situ scrubber to transform the acid-gas forming components of the waste into neutral salts and immobilizes potentially fugitive materials by a combination of particle wetting, encapsulation and chemical dissolution and solvation. Because the offgas is collected and assayed before release, and wastes containing toxic and radioactive materials are treated while immobilized in a condensed phase, the process avoids the problems sometimes associated with incineration processes. We are studying a potentially improved modification of this process, which treats oxidizable wastes in two stages: pyrolysis followed by catalyzed molten salt oxidation of the pyrolysis gases at ca. 700{degrees}C. 15 refs., 5 figs., 1 tab.

  19. Density functional theory study of oxygen migration in molten carbonate

    NASA Astrophysics Data System (ADS)

    Lei, Xueling; Haines, Kahla; Huang, Kevin; Qin, Changyong

    2016-02-01

    The process of oxygen migration in alkali molten carbonate salts has been examined using density functional theory method. All geometries were optimized at the B3LYP/6-31G(d) level, while single point energy corrections were performed using MP4 and CCSD(T). At TS, a O-O-O linkage is formed and O-O bond forming and breaking is concerted. A cooperative "cogwheel" mechanism as described in the equation of CO42- + CO32- → CO32- ⋯O ⋯ CO32- → CO32- + CO42- is involved. The energy barrier is calculated to be 103.0, 136.3 and 127.9 kJ/mol through an intra-carbonate pathway in lithium, sodium and potassium carbonate, respectively. The reliability and accuracy of B3LYP/6-31G(d) were confirmed by CCSD(T). The calculated low values of activation energy indicate that the oxygen transfer in molten carbonate salts is fairly easy. In addition, it is found that lithium carbonate is not only a favorable molten carbonate salt for better cathode kinetics, but also it is widely used for reducing the melting point of Li/Na and Li/K eutectic MC mixtures. The current results imply that the process of oxygen reduction in MC modified cathodes is facilitated by the presence of MC, resulting in an enhancement of cell performance at low operating temperatures.

  20. ac impedance measurements of molten salt thermal batteries

    NASA Astrophysics Data System (ADS)

    Singh, Pritpal; Guidotti, Ronald A.; Reisner c, David

    Non-destructive testing of thermal batteries without activating them is a challenging proposition. Molten salt thermal batteries are activated by raising their temperature to above the melting point of the salt constituting the electrolyte. One approach that we have considered is to raise the temperature of the molten salt electrolyte to a temperature below the melting point so that the battery does not get activated yet may provide sufficient mobility of the ionic species to be able to obtain some useful ac impedance measurements. This hypothesis was put to the test for two Li(Si)/FeS 2 molten salt batteries with two electrolytes of different melting points—a standard LiCl-KCl eutectic that melts at 352 °C and a LiBr-KBr-LiCl eutectic with a melting point of 319 °C. ac impedance measurements as a function of frequency and temperature below the melting point are presented for single cells and batteries.