Science.gov

Sample records for situ structure-function studies

  1. Two-dimensional boron nitride structures functionalization: first principles studies.

    PubMed

    Ponce-Pérez, R; Cocoletzi, Gregorio H; Takeuchi, Noboru

    2016-09-01

    Density functional theory calculations have been performed to investigate two-dimensional hexagonal boron nitride (2D hBN) structures functionalization with organic molecules. 2x2, 4x4 and 6x6 periodic 2D hBN layers have been considered to interact with acetylene. To deal with the exchange-correlation energy the generalized gradient approximation (GGA) is invoked. The electron-ion interaction is treated with the pseudopotential method. The GGA with the Perdew-Burke-Ernzerhoff (PBE) functionals together with van der Waals interactions are considered to deal with the composed systems. To investigate the functionalization two main configurations have been explored; in one case the molecule interacts with the boron atom and in the other with the nitrogen atom. Results of the adsorption energies indicate chemisorption in both cases. The total density of states (DOS) displays an energy gap in both cases. The projected DOS indicate that the B-p and N-p orbitals are those that make the most important contribution in the valence band and the H-s and C-p orbitals provide an important contribution in the conduction band to the DOS. Provided that the interactions of the acetylene with the 2D layer modify the structural and electronic properties of the hBN the possibility of structural functionalization using organic molecules may be concluded.

  2. Aromatase, estrone sulfatase, and 17β-hydroxysteroid dehydrogenase: structure-function studies and inhibitor development.

    PubMed

    Hong, Yanyan; Chen, Shiuan

    2011-07-04

    Aromatase, estrone sulfatase, and 17β-hydroxysteroid dehydrogenase type 1 are involved in the key steps of 17β-estradiol biosynthesis. Structure-function studies of aromatase, estrone sulfatase and 17β-hydroxysteroid dehydrogenase type 1 are important to evaluate the molecular basis of the interaction between these enzymes and their inhibitors. Selective and potent inhibitors of the three enzymes have been developed as antiproliferative agents in hormone-dependent breast carcinoma. New treatment strategies for hormone-dependent breast cancer are discussed.

  3. [Obtaining of the affinity purified antibodies against survivin for the structure functional study of the protein].

    PubMed

    Akhidova, E V; Volkova, T D; Koroev, D O; Yakupov, I Iu; Kalintseva, M V; Zavalishina, L E; Kaplun, A P; Zharskaia, O O; Zatsepina, O V; Vol'pina, O M

    2013-01-01

    Tumor-associated protein survivin is the bifunctional protein which can participate either in cell division regulation or in apoptosis inhibition depending on its localization and structure state. The aim of this work was to obtain monospecific antibodies useful for investigation of protein structure and functional features. Six affinity purified antibodies directed to different protein regions were obtained. The ability of antibodies obtained to detect survivin in tumor cells and breast cancer tissues was studied. It was shown that antibodies to (1-22) and (95-105) survivin fragments have the highest specific activity. In western-blot antibodies to (1-22) region predominantly binds with survivin-containing complex, which may be the survivin dimer as we suppose, while antibodies to (95-105) region detects only monomeric form of the protein. Breast cancer tissues study demonstrated that survivin monomer presents only in the tumor core tissues, while survivin-containing complex is expressed both in tumor core and tumor periphery tissues. It was shown that antibodies to (1-22) fragment detect predominantly nuclear survivin, which participates in mitosis regulation, while antibodies to (95-105) fragment gave nucleoplasm and cytoplasm staining at all stages of cell cycle. Thereby antibodies obtained are the useful tool for structure-functional study of survivin.

  4. Genetic and structure-function studies of missense mutations in human endothelial lipase.

    PubMed

    Razzaghi, Hamid; Tempczyk-Russell, Anna; Haubold, Kurt; Santorico, Stephanie A; Shokati, Touraj; Christians, Uwe; Churchill, Mair E A

    2013-01-01

    Endothelial lipase (EL) plays a pivotal role in HDL metabolism. We sought to characterize EL and its interaction with HDL as well as its natural variants genetically, functionally and structurally. We screened our biethnic population sample (n = 802) for selected missense mutations (n = 5) and identified T111I as the only common variant. Multiple linear regression analyses in Hispanic subjects revealed an unexpected association between T111I and elevated LDL-C (p-value = 0.012) and total cholesterol (p-value = 0.004). We examined lipase activity of selected missense mutants (n = 10) and found different impacts on EL function, ranging from normal to complete loss of activity. EL-HDL lipidomic analyses indicated that EL has a defined remodeling of HDL without exhaustion of the substrate and a distinct and preference for several fatty acids that are lipid mediators and known for their potent pro- and anti-inflammatory properties. Structural studies using homology modeling revealed a novel α/β motif in the C-domain, unique to EL. The EL dimer was found to have the flexibility to expand and to bind various sizes of HDL particles. The likely impact of the all known missense mutations (n = 18) on the structure of EL was examined using molecular modeling and the impact they may have on EL lipase activity using a novel structure-function slope based on their structural free energy differences. The results of this multidisciplinary approach delineated the impact of EL and its variants on HDL. Moreover, the results suggested EL to have the capacity to modulate vascular health through its role in fatty acid-based signaling pathways.

  5. A detailed study of nucleon structure function in nuclei in the valence quark region

    SciTech Connect

    Bianchi, N.

    1994-04-01

    The so called {open_quotes}EMC effect{close_quotes} discovered during the 1980`s, has caused a big controversy in the community of nuclear and high energy physicists; during the last ten years, five experiments have been performed in different laboratories and several hundreds of papers about the possible interpretation of the modification of the nucleon structure function inside nuclei have been published. However, from the experimental point of view, the main goal of four experiments (EMC, BCDMS, NMC, FNAL) has been to emphasize the region of low x{sub b}, where shadowing effects appear. In the region of valence quarks and nuclear effects (x{sub b} > 0.1 - 0.2) the most reliable data presently available are from the SLAC E139 experiment performed in 1983 with only 80 hours of beam time. New precise data in the valence quark region are necessary to measure separate structure functions F{sub 2}(x{sub b}, Q{sup 2}) and R{sup lt}(x{sub b},Q{sup 2}) = {sigma}{sub l}/{sigma}{sub t}, and to investigate the real A-dependence of the ratio between bound and free-nucleon structure functions which is not completely defined by the SLAC data. Moreover, from the nuclear physics point of view, a measurement on some unexplored nuclei, like {sup 3}He and {sup 48}Ca, would be of great interest. The intermediate scaling region (0.1 < x{sub b} < 0.7) would be accessible at CEBAF if the machine energy will reach 6-8 GeV, as suggested by all the tests performed on the RF cavities. This physics program has been already presented in two letter of intents.

  6. A structure-function study of MID1 mutations associated with a mild Opitz phenotype.

    PubMed

    Mnayer, Laila; Khuri, Sawsan; Merheby, Hassan Al-Ali; Meroni, Germana; Elsas, Louis J

    2006-03-01

    The X-linked form of Opitz syndrome (OS) affects midline structures and produces a characteristic, but heterogeneous, phenotype that may include severe mental retardation, hypertelorism, broad nasal bridge, widow's peak, cleft lip/cleft palate, congenital heart disease, laryngotracheal defects, and hypospadias. The MID1 gene was implicated in OS by linkage to Xp22. It encodes a 667 amino acid protein that contains a RING finger motif, two B-box zinc fingers, a coiled-coil, a fibronectin type III (FNIII) domain, and a B30.2 domain. Several mutations in MID1 are associated with severe OS. Here, we describe an intelligent male with a milder phenotype characterized by hypertelorism, broad nasal bridge, widow's peak, mild hypospadias, pectus excavatum, and a surgically corrected tracheo-esophageal fistula. He has an above average intelligence and no cleft lip/palate or heart disease. We identified a novel mutation in MID1 (P441L) which is in exon 8 and functionally associated with the FNIII domain. While OS phenotypes have been attributed to mutations in the C-terminal part of MID1, little is currently known about the structure-function relationships of MID1 mutations, and how they affect phenotype. We find from a literature review that missense mutations within the FNIII domain of MID1 are associated with a milder presentation of OS than missense mutations elsewhere in MID1. All truncating mutations (frameshift, insertions/deletions) lead to severe OS. We used homology analysis of the MID1 FNIII domain to investigate structure-function changes caused by our missense mutation. This and other missense mutations probably cause disruption of protein-protein interactions, either within MID1 or between MID1 and other proteins. We correlate these protein structure-function findings to the absence of CNS or palatal changes and conclude that the FNIII domain of the MID1 protein may be involved in midline differentiation after neural tube and palatal structures are completed.

  7. Structure-function studies of the lustrin A polyelectrolyte domains, RKSY and D4.

    PubMed

    Wustman, Brandon A; Weaver, James C; Morse, Daniel E; Evans, John Spencer

    2003-01-01

    The lustrin superfamily represents a unique group of biomineralization proteins localized between layered aragonite mineral plates (i.e., nacre layers) in mollusk shell. These proteins not only exhibit elastomeric behavior within the mineralized matrix, but also adhesion to the aragonite-containing composite layer. One member of the lustrin superfamily, Lustrin A, has been sequenced; the protein is organized into defined, modular sequence domains that are hypothesized to perform separate functions (i.e., force unfolding, mineral adhesion, intermolecular binding) within the Lustrin A protein. Using nuclear magnetic resonance (NMR) and in vitro mineralization assays, we investigated structure-function relationships for two Lustrin A putative mineral binding domains, the 30 AA Arg, Lys, Tyr, Ser-rich (RKSY) and the 24 AA Asp-rich (D4) sequence regions domain of the Lustrin A protein. The results indicate that both sequences adopt open, unfolded structures that represent either extended or random coil states. Using geologic calcite overgrowth assays and scanning electron microscopic analyses, we observe that the RKSY polypeptide does not significantly perturb calcium carbonate growth. However, the D4 domain does influence crystal growth in a concentration-dependent manner. Collectively, our data indicate that D4, and not the RKSY domain, exhibits structure-function activity consistent with a mineral binding region.

  8. Structure-function study of the fourth transmembrane segment of the GABAρ1 receptor

    PubMed Central

    Estrada-Mondragón, Argel; Reyes-Ruiz, Jorge Mauricio; Martínez-Torres, Ataúlfo; Miledi, Ricardo

    2010-01-01

    The Cys-loop family of receptors mediates synaptic neurotransmission in the central nervous system of vertebrates. These receptors share several structural characteristics and assemble in the plasma membrane as multimers with fivefold symmetry. Of these, the ionotropic GABA receptors are key players in the pathogenesis of diseases like epilepsy, anxiety, and schizophrenia. Different experimental approaches have shed some light on the mechanisms behind the function of these receptors; but little is known about their structure at high resolution. Sequence homology with the nicotinic acetylcholine receptor predicts that ionotropic GABA receptors possess four transmembrane segments (TM1–4) and that TM2 forms the wall of the ion channel. However, the role of the other three segments is unclear. The GABAρ1 receptor plays a fundamental role in the regulation of neurotransmission along the visual pathway, is highly sensitive to GABA, and exhibits little desensitization. In our recent investigations of the role of TM4 in receptor function, a key residue in this domain (W475) was found to be involved in activation of the receptor. Here we have generated a structural model of the GABAρ1 receptor in silico and assessed its validity by electrophysiologically testing nine amino acid substitutions of W475 and deletions of the neighboring residues (Y474 and S476). The results identify a critical linkage between the ligand-binding domain and the TM4 domain and provide a framework for more detailed structure-function analyses of ionotropic GABA receptors. PMID:20876117

  9. Photon structure function - theory

    SciTech Connect

    Bardeen, W.A.

    1984-12-01

    The theoretical status of the photon structure function is reviewed. Particular attention is paid to the hadronic mixing problem and the ability of perturbative QCD to make definitive predictions for the photon structure function. 11 references.

  10. Mutants of Chlamydomonas: tools to study thylakoid membrane structure, function and biogenesis.

    PubMed

    de Vitry, C; Vallon, O

    1999-06-01

    The unicellular green alga Chlamydomonas reinhardtii is a model system for the study of photosynthesis and chloroplast biogenesis. C. reinhardtii has a photosynthesis apparatus similar to that of higher plants and it grows at rapid rate (generation time about 8 h). It is a facultative phototroph, which allows the isolation of mutants unable to perform photosynthesis and its sexual cycle allows a variety of genetic studies. Transformation of the nucleus and chloroplast genomes is easily performed. Gene transformation occurs mainly by homologous recombination in the chloroplast and heterologous recombination in the nucleus. Mutants are precious tools for studies of thylakoid membrane structure, photosynthetic function and assembly. Photosynthesis mutants affected in the biogenesis of a subunit of a protein complex usually lack the entire complex; this pleiotropic effect has been used in the identification of the other subunits, in the attribution of spectroscopic signals and also as a 'genetic cleaning' process which facilitates both protein complex purification, absorption spectroscopy studies or freeze-fracture analysis. The cytochrome b6f complex is not required for the growth of C. reinhardtii, unlike the case of photosynthetic prokaryotes in which the cytochrome complex is also part of the respiratory chain, and can be uniquely studied in Chlamydomonas by genetic approaches. We describe in greater detail the use of Chlamydomonas mutants in the study of this complex.

  11. In Situ Vitrification Treatability Study Work Plan

    SciTech Connect

    Charboneau, B.L.; Landon, J.L.

    1989-03-01

    The Buried Waste Program was established in October, 1987 to accelerate the studies needed to develop a recommended long-term management plan for the buried mixed waste at the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory. The In Situ Vitrification Project is being conducted in a Comprehensive Environmental Response, Compensation, and Liability Act Feasibility Study format to identify methods for the long-term management of the mixed waste buried. This In Situ Vitrification Treatability Study Work Plan gives a brief description of the site, work breakdown structure, and project organization: the in situ vitrification technology; the purpose of the tests and demonstrations; and the equipment and materials required for the tests and demonstration. 5 refs., 6 figs., 3 tabs.

  12. Whale (Balaenoptera physalus) haemoglobin: primary structure, functional characterisation and computer modelling studies.

    PubMed

    Corda, Marcella; Tamburrini, Maurizio; De Rosa, Maria C; Sanna, Maria T; Fais, Antonella; Olianas, Alessandra; Pellegrini, Mariagiuseppina; Giardina, Bruno; di Prisco, Guido

    2003-01-01

    The functional properties of haemoglobin from the Mediterranean whale Balaenoptera physalus have been studied as functions of heterotropic effector concentration and temperature. Particular attention has been given to the effect of carbon dioxide and lactate since the animal is specialised for prolonged dives often in cold water. The molecular basis of the functional behaviour and in particular of the weak interaction with 2,3-diphosphoglycerate is discussed in the light of the primary structure and of computer modelling. On these bases, it is suggested that the A2 (Pro-->Ala) substitution observed in the beta chains of whale haemoglobin may be responsible for the displacement of the A helix known to be a key structural feature in haemoglobins that display an altered interaction with 2,3-diphosphoglycerate as compared with human haemoglobin. The functional and structural results, discussed in the light of a previous study on the haemoglobin from the Arctic whale Balaenoptera acutorostrata, give further insights into the regulatory mechanisms of the interactive effects of temperature, carbon dioxide and lactate.

  13. Structure-Function Study of Tertiary Amines as Switchable Polarity Solvents

    SciTech Connect

    Aaron D. Wilson; Frederick F. Stewart

    2014-02-01

    A series of tertiary amines have been screened for their function as switchable polarity solvents (SPS). The relative ratios of tertiary amine and carbonate species as well as maximum possible concentration were determined through quantitative 1H and 13C NMR spectroscopy. The viscosities of the polar SPS solutions were measured and ranged from near water in dilute systems through to gel formation at high concentrations. The van't Hoff indices for SPS solutions were measured through freezing point depression studies as a proxy for osmotic pressures. A new form of SPS with an amine : carbonate ratio significantly greater than unity has been identified. Tertiary amines that function as SPS at ambient pressures appear to be limited to molecules with fewer than 12 carbons. The N,N-dimethyl-n-alkylamine structure has been identified as important to the function of an SPS.

  14. Structure-Functional Study of Tyrosine and Methionine Dipeptides: An Approach to Antioxidant Activity Prediction

    PubMed Central

    Torkova, Anna; Koroleva, Olga; Khrameeva, Ekaterina; Fedorova, Tatyana; Tsentalovich, Mikhail

    2015-01-01

    Quantum chemical methods allow screening and prediction of peptide antioxidant activity on the basis of known experimental data. It can be used to design the selective proteolysis of protein sources in order to obtain products with antioxidant activity. Molecular geometry and electronic descriptors of redox-active amino acids, as well as tyrosine and methionine-containing dipeptides, were studied by Density Functional Theory method. The calculated data was used to reveal several descriptors responsible for the antioxidant capacities of the model compounds based on their experimentally obtained antioxidant capacities against ABTS (2,2′-Azino-bis-(3-ethyl-benzothiazoline-6-sulfonate)) and peroxyl radical. A formula to predict antioxidant activity of peptides was proposed. PMID:26512651

  15. The influence of cholesterol on membrane protein structure, function, and dynamics studied by molecular dynamics simulations.

    PubMed

    Grouleff, Julie; Irudayam, Sheeba Jem; Skeby, Katrine K; Schiøtt, Birgit

    2015-09-01

    The plasma membrane, which encapsulates human cells, is composed of a complex mixture of lipids and embedded proteins. Emerging knowledge points towards the lipids as having a regulating role in protein function. Furthermore, insight from protein crystallography has revealed several different types of lipids intimately bound to membrane proteins and peptides, hereby possibly pointing to a site of action for the observed regulation. Cholesterol is among the lipid membrane constituents most often observed to be co-crystallized with membrane proteins, and the cholesterol levels in cell membranes have been found to play an essential role in health and disease. Remarkably little is known about the mechanism of lipid regulation of membrane protein function in health as well as in disease. Herein, we review molecular dynamics simulation studies aimed at investigating the effect of cholesterol on membrane protein and peptide properties. This article is part of a Special Issue entitled: Lipid-protein interactions.

  16. Structure/function studies of dogfish α-crystallin, comparison with bovine α-crystallin

    PubMed Central

    Ghahghaei, A.; Rekas, A.; Carver, J.A.

    2009-01-01

    Purpose α-Crystallin is the major protein of the mammalian lens where it contributes to the refractive properties needed for vision and possibly to the stability of the tissue. The aim of this study was to determine whether the properties of α-crystallin have changed during the course of evolution. Methods Dogfish α-crystallin, which appeared over 420 million years ago, has been contrasted with bovine α-crystallin, which emerged around 160 million years later, by comparing their sizes, the microenvironments of their cysteine and tryptophan residues, their chaperone-like activities and the flexibility of their COOH-terminal extensions. Results Dogfish α-crystallin consists of αA- and αB-polypeptides, in a 1:5 ratio, and has a molecular mass of around 400 kDa. By contrast, the bovine protein is around 600-800 kDa in mass and has a 3:1 subunit ratio. Cysteine residues in the proteins were equally accessible to reaction with 5,5'-dithiobis-(2-nitrobenzoic acid). Quenching of fluorescence with acrylamide indicated tryptophan residues in the two proteins were in similar environments. The chaperone activity of dogfish α-crystallin was comparable to that of bovine α-crystallin in preventing the heat-induced precipitation of βL-crystallin but the dogfish protein was three times more effective at preventing insulin precipitation after reduction at 37 ˚C. 1H nuclear magnetic resonance spectroscopic studies showed that the last 17 amino acids of the dogfish αB polypeptide (V162-K178) have great conformational flexibility, are highly exposed to solvent and adopt little ordered conformation. This is comparable to, but slightly longer in length, than the COOH-terminal extension observed in mammalian α-crystallins. Conclusions The structure and properties of α-crystallin have changed relatively little during the evolutionary period from the emergence of sharks and mammals. PMID:19956560

  17. The application of psoralens to the study of DNA structure, function and dynamics

    SciTech Connect

    Spielmann, P.H. |

    1991-04-01

    A series of six nitroxide spin-labeled psoralens were designed, synthesized and tested as probes for DNA dynamics. The synthesis of these spin-labeled psoralen derivatives and their photoreactivity with double-stranded DNA fragments is described. The spin labels (nitroxides) were demonstrated to survive the uv irradiation required to bind the probe to the target DNA. EPR spectra of the photobound spin-labels indicate that they do not wobble with respect to the DNA on the time-scales investigated. The author has used psoralen modified DNA as a model for the study of DNA repair enzyme systems in human cell free extracts. He has shown that damage-induced DNA synthesis is associated with removal of psoralen adducts and therefore is {open_quotes}repair synthesis{close_quotes} and not an aberrant DNA synthesis reaction potentiated by deformation of the DNA by adducts. He has found that all DNA synthesis induced by psoralen monoadducts is the consequence of removal of these adducts. By the same approach he has obtained evidence that this in vitro system is capable of removing psoralen cross-links as well. Reported here are synthetic methods that make use of high intensity lasers coupled with HPLC purification to make homogeneous and very pure micromole quantities of furan-side monoadducted, cross-linked, and pyrone-side monoadducted DNA oligonucleotide. These molecules are currently being studied by NMR and X-ray crystallography. The application of the site-specifically psoralen modified oligonucleotide synthesized by these methods to the construction of substrates for the investigation of DNA repair is also discussed.

  18. Improved purification of native meningococcal porin PorB and studies on its structure/function.

    PubMed

    Massari, Paola; King, Carol A; MacLeod, Heather; Wetzler, Lee M

    2005-12-01

    The outer membrane protein PorB of Neisseria meningitidis is a pore-forming protein which has various effects on eukaryotic cells. It has been shown to (1) up-regulate the surface expression of the co-stimulatory molecule CD86 and of MHC class II (which are TLR2/MyD88 dependent and related to the porin's immune-potentiating ability), (2) be involved in prevention of apoptosis by modulating the mitochondrial membrane potential, and (3) form pores in eukaryotic cells. As an outer membrane protein, its native trimeric form isolation is complicated by its insoluble nature, requiring the presence of detergent throughout the whole procedure, and by its tight association with other outer membrane components, such as neisserial LOS or lipoproteins. In this study, an improved chromatographic purification method to obtain an homogeneous product free of endotoxin and lipoprotein is described, without loss of any of the above-mentioned properties of the porin. Furthermore, we have investigated the requirement of the native trimeric structure for the porin's activity. Inactivation of functional PorB trimers into non-functional monomers was achieved by incubation on ice. Thus, routine long- and medium-term storage at low temperature may be a cause of porin inactivation.

  19. Facilitating Structure-Function Studies of CFTR Modulator Sites with Efficiencies in Mutagenesis and Functional Screening.

    PubMed

    Molinski, Steven V; Ahmadi, Saumel; Hung, Maurita; Bear, Christine E

    2015-12-01

    There are nearly 2000 mutations in the CFTR gene associated with cystic fibrosis disease, and to date, the only approved drug, Kalydeco, has been effective in rescuing the functional expression of a small subset of these mutant proteins with defects in channel activation. However, there is currently an urgent need to assess other mutations for possible rescue by Kalydeco, and further, definition of the binding site of such modulators on CFTR would enhance our understanding of the mechanism of action of such therapeutics. Here, we describe a simple and rapid one-step PCR-based site-directed mutagenesis method to generate mutations in the CFTR gene. This method was used to generate CFTR mutants bearing deletions (p.Gln2_Trp846del, p.Ser700_Asp835del, p.Ile1234_Arg1239del) and truncation with polyhistidine tag insertion (p.Glu1172-3Gly-6-His*), which either recapitulate a disease phenotype or render tools for modulator binding site identification, with subsequent evaluation of drug responses using a high-throughput (384-well) membrane potential-sensitive fluorescence assay of CFTR channel activity within a 1 wk time frame. This proof-of-concept study shows that these methods enable rapid and quantitative comparison of multiple CFTR mutants to emerging drugs, facilitating future large-scale efforts to stratify mutants according to their "theratype" or most promising targeted therapy.

  20. Deuterium Labeling Strategies for Creating Contrast in Structure-Function Studies of Model Bacterial Outer Membranes Using Neutron Reflectometry.

    PubMed

    Le Brun, Anton P; Clifton, Luke A; Holt, Stephen A; Holden, Peter J; Lakey, Jeremy H

    2016-01-01

    Studying the outer membrane of Gram-negative bacteria is challenging due to the complex nature of its structure. Therefore, simplified models are required to undertake structure-function studies of processes that occur at the outer membrane/fluid interface. Model membranes can be created by immobilizing bilayers to solid supports such as gold or silicon surfaces, or as monolayers on a liquid support where the surface pressure and fluidity of the lipids can be controlled. Both model systems are amenable to having their structure probed by neutron reflectometry, a technique that provides a one-dimensional depth profile through a membrane detailing its thickness and composition. One of the strengths of neutron scattering is the ability to use contrast matching, allowing molecules containing hydrogen and those enriched with deuterium to be highlighted or matched out against the bulk isotopic composition of the solvent. Lipopolysaccharides, a major component of the outer membrane, can be isolated for incorporation into model membranes. Here, we describe the deuteration of lipopolysaccharides from rough strains of Escherichia coli for incorporation into model outer membranes, and how the use of deuterated materials enhances structural analysis of model membranes by neutron reflectometry.

  1. Structure function monitor

    DOEpatents

    McGraw, John T [Placitas, NM; Zimmer, Peter C [Albuquerque, NM; Ackermann, Mark R [Albuquerque, NM

    2012-01-24

    Methods and apparatus for a structure function monitor provide for generation of parameters characterizing a refractive medium. In an embodiment, a structure function monitor acquires images of a pupil plane and an image plane and, from these images, retrieves the phase over an aperture, unwraps the retrieved phase, and analyzes the unwrapped retrieved phase. In an embodiment, analysis yields atmospheric parameters measured at spatial scales from zero to the diameter of a telescope used to collect light from a source.

  2. Microfluidic neurite guidance to study structure-function relationships in topologically-complex population-based neural networks

    NASA Astrophysics Data System (ADS)

    Honegger, Thibault; Thielen, Moritz I.; Feizi, Soheil; Sanjana, Neville E.; Voldman, Joel

    2016-06-01

    The central nervous system is a dense, layered, 3D interconnected network of populations of neurons, and thus recapitulating that complexity for in vitro CNS models requires methods that can create defined topologically-complex neuronal networks. Several three-dimensional patterning approaches have been developed but none have demonstrated the ability to control the connections between populations of neurons. Here we report a method using AC electrokinetic forces that can guide, accelerate, slow down and push up neurites in un-modified collagen scaffolds. We present a means to create in vitro neural networks of arbitrary complexity by using such forces to create 3D intersections of primary neuronal populations that are plated in a 2D plane. We report for the first time in vitro basic brain motifs that have been previously observed in vivo and show that their functional network is highly decorrelated to their structure. This platform can provide building blocks to reproduce in vitro the complexity of neural circuits and provide a minimalistic environment to study the structure-function relationship of the brain circuitry.

  3. Microfluidic neurite guidance to study structure-function relationships in topologically-complex population-based neural networks

    PubMed Central

    Honegger, Thibault; Thielen, Moritz I.; Feizi, Soheil; Sanjana, Neville E.; Voldman, Joel

    2016-01-01

    The central nervous system is a dense, layered, 3D interconnected network of populations of neurons, and thus recapitulating that complexity for in vitro CNS models requires methods that can create defined topologically-complex neuronal networks. Several three-dimensional patterning approaches have been developed but none have demonstrated the ability to control the connections between populations of neurons. Here we report a method using AC electrokinetic forces that can guide, accelerate, slow down and push up neurites in un-modified collagen scaffolds. We present a means to create in vitro neural networks of arbitrary complexity by using such forces to create 3D intersections of primary neuronal populations that are plated in a 2D plane. We report for the first time in vitro basic brain motifs that have been previously observed in vivo and show that their functional network is highly decorrelated to their structure. This platform can provide building blocks to reproduce in vitro the complexity of neural circuits and provide a minimalistic environment to study the structure-function relationship of the brain circuitry. PMID:27328705

  4. In situ synthesis studies of silicon clathrates

    NASA Astrophysics Data System (ADS)

    Hutchins, Peter Thomas

    Solid state clathrates have shown considerable potential as a new class of materials over the past 30 years. Experimental and theoretical studies have shown that precise tuning and synthetic control of these materials, may lead to desirable properties. Very little is known about the mechanism of formation of the clathrates and so the desire to have accurate synthetic control was, until now, unrealistic. This thesis address the problem using in situ synchrotron x-ray techniques. In this study, experiments were designed to utilise time-resolved in situ diffraction techniques and high temperature 23Na NMR, in efforts to understand the mechanism of formation for this class of expanded framework materials. A complex high vacuum capillary synthesis cell was designed for loading under inert conditions and operation under high vacuum at station 6.2 of the SRS Daresbury. The cell was designed to operate in conjunction with a custom made furnace capable of temperatures in excess of 1000 C, as well as a vacuum system capable of 10"5 bar. The clathrate system was studied in situ, using rapid data collection to elucidate the mechanism of formation. The data were analysed using Rietveld methods and showed a structural link between the monoclinic, C2/c, Zintl precursors and the cubic, Pm3n, clathrate I phase. The phases were found to be linked by relation of the sodium planes in the silicide and the sodium atoms resident at cages centres in the clathrate system. This evidence suggests the guest species is instrumental in formation of the clathrate structure by templating the formation of the cages in the structure. Solid state 23Na NMR was utilised to complete specially design experiments, similar to those complete in situ using synchrotron x-ray techniques. The experiments showed increased spherical symmetry of the alkali metal sites and suggested increased mobility of the guest atoms during heating. In addition, cyclic heating experiments using in situ diffraction showed

  5. In-situ studies of nanocatalysis.

    PubMed

    Zhang, Shiran; Nguyen, Luan; Zhu, Yuan; Zhan, Sihui; Tsung, Chia-Kuang Frank; Tao, Franklin Feng

    2013-08-20

    A heterogeneous catalyst in industry consists of nanoparticles with variable crystallite sizes, shapes, and compositions. Its catalytic performance (activity, selectivity, and durability) derives from surface chemistry of catalyst nanoparticles during catalysis. However, the surface chemistry of the catalyst particles during catalysis, termed in-situ information, is a "black box" because of the challenges in characterizing the catalysts during catalysis. The lack of such in-situ information about catalysts has limited the understanding of catalytic mechanisms and the development of catalysts with high selectivity and activity. The challenges in understanding heterogeneous catalysis include measurement of reaction kinetics, identification of reaction intermediates, bridging pressure gap and materials gap. The pressure gap is the difference in surface structure and chemistry between a catalyst during catalysis and under an ultrahigh vacuum (UHV) condition. The materials gap represents the difference between the structural and compositional complexity of industrial catalysts and the well-defined surface of model catalysts of metals or oxides. Development of in-situ characterization using electron spectroscopy and electron microscopy in recent decades has made possible studies of surface chemistry and structure of nanocatalysts under reaction conditions or during catalysis at near ambient pressure. In this Account, we review the new chemistries and structures of nanocatalysts during reactions revealed with in-situ analytical techniques. We discuss changes observed during catalysis including the evolution of composition, oxidation state, phase, and geometric structure of the catalyst surface, and the sintering of catalysts. These surface chemistries and structures have allowed researchers to build a correlation between surface chemistry and structure of active nanocatalysts and their corresponding catalytic performances. Such a correlation provides critical insights for

  6. Monoclonal antibodies for structure-function studies of (R)-3-hydroxybutyrate dehydrogenase, a lipid-dependent membrane-bound enzyme.

    PubMed Central

    Adami, P; Duncan, T M; McIntyre, J O; Carter, C E; Fu, C; Melin, M; Latruffe, N; Fleischer, S

    1993-01-01

    Monoclonal antibodies (mAbs) have been used to study structure-function relationships of (R)-3-hydroxybutyrate dehydrogenase (BDH) (EC 1.1.1.30), a lipid-requiring mitochondrial membrane enzyme with an absolute and specific requirement for phosphatidylcholine (PC) for enzymic activity. The purified enzyme (apoBDH, devoid of phospholipid and thereby inactive) can be re-activated with preformed phospholipid vesicles containing PC or by short-chain soluble PC. Five of six mAbs cross-react with BDH from bovine heart and rat liver, including two mAbs to conformational epitopes. One mAb was found to be specific for the C-terminal sequence of BDH and served to: (1) map endopeptidase cleavage and epitope sites on BDH; and (2) demonstrate that the C-terminus is essential for the activity of BDH. Carboxypeptidase cleavage of only a few (< or = 14) C-terminal amino acids from apoBDH (as detected by the loss of C-terminal epitope for mAb 3-10A) prevents activation by either bilayer or soluble PC. Further, for BDH in bilayers containing PC, the C-terminus is protected from carboxy-peptidase cleavage, whereas in bilayers devoid of PC the C-terminus is cleaved, and subsequent activation by PC is precluded. We conclude that: (1) the C-terminus of BDH is essential for enzymic activity, consistent with the prediction, from primary sequence analysis, that the PC-binding site is in the C-terminal domain of BDH; and (2) the allosteric activation of BDH by PC in bilayers protects the C-terminus from carboxypeptidase cleavage, indicative of a PC-induced conformational change in the enzyme. Images Figure 1 Figure 3 Figure 4 Figure 6 PMID:7686368

  7. Complete backbone and DENQ side chain NMR assignments in proteins from a single experiment: implications to structure-function studies.

    PubMed

    Reddy, Jithender G; Hosur, Ramakrishna V

    2014-03-01

    Resonance assignment is the first and the most crucial step in all nuclear magnetic resonance (NMR) investigations on structure-function relationships in biological macromolecules. Often, the assignment exercise has to be repeated several times when specific interactions with ligands, substrates etc., have to be elucidated for understanding the functional mechanisms. While the protein backbone serves to provide a scaffold, the side chains interact directly with the ligands. Such investigations will be greatly facilitated, if there are rapid methods for obtaining exhaustive information with minimum of NMR experimentation. In this context, we present here a pulse sequence which exploits the recently introduced technique of parallel detection of multiple nuclei, e.g. (1)H and (13)C, and results in two 3D-data sets simultaneously. These yield complete backbone resonance assignment ((1)H(N), (15)N, (13)CO, (1)Hα/(13)Cα, and (1)Hβ/(13)Cβ chemical shifts) and side chain assignment of D, E, N and Q residues. Such an exhaustive assignment has the potential of yielding accurate 3D structures using one or more of several algorithms which calculate structures of the molecules very reliably on the basis of NMR chemical shifts alone. The side chain assignments of D, E, N, and Q will be extremely valuable for interaction studies with different ligands; D and E side chains are known to be involved in majority of catalytic activities. Utility of this experiment has been demonstrated with Ca(2+) bound M-crystallin, which contains largely D, E, N and Q residues at the metal binding sites.

  8. The Neutron Structure Function

    NASA Astrophysics Data System (ADS)

    Holt, Roy

    2013-10-01

    Knowledge of the neutron structure function is important for testing models of the nucleon, for a complete understanding of deep inelastic scattering (DIS) from nuclei, and for high energy experiments. As there exist no free neutron targets, neutron structure functions have been determined from deep inelastic scattering from the deuteron. Unfortunately, the short-range part of the deuteron wave function becomes important in extracting the neutron structure function at very high Bjorken x. New methods have been devised for Jefferson Lab experiments to mitigate this problem. The BONUS experiment involves tagging spectator neutrons in the deuteron, while the MARATHON experiment minimizes nuclear structure effects by a comparison of DIS from 3H and 3He. A summary of the status and future plans will be presented. This work supported by the U. S. Department of Energy, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

  9. Atomic force microscopy study of the structure function relationships of the biofilm-forming bacterium Streptococcus mutans

    NASA Astrophysics Data System (ADS)

    Cross, Sarah E.; Kreth, Jens; Zhu, Lin; Qi, Fengxia; Pelling, Andrew E.; Shi, Wenyuan; Gimzewski, James K.

    2006-02-01

    Atomic force microscopy (AFM) has garnered much interest in recent years for its ability to probe the structure, function and cellular nanomechanics inherent to specific biological cells. In particular, we have used AFM to probe the important structure-function relationships of the bacterium Streptococcus mutans. S. mutans is the primary aetiological agent in human dental caries (tooth decay), and is of medical importance due to the virulence properties of these cells in biofilm initiation and formation, leading to increased tolerance to antibiotics. We have used AFM to characterize the unique surface structures of distinct mutants of S. mutans. These mutations are located in specific genes that encode surface proteins, thus using AFM we have resolved characteristic surface features for mutant strains compared to the wild type. Ultimately, our characterization of surface morphology has shown distinct differences in the local properties displayed by various S. mutans strains on the nanoscale, which is imperative for understanding the collective properties of these cells in biofilm formation.

  10. A long-term study of AGN X-ray variability . Structure function analysis on a ROSAT-XMM quasar sample

    NASA Astrophysics Data System (ADS)

    Middei, R.; Vagnetti, F.; Bianchi, S.; La Franca, F.; Paolillo, M.; Ursini, F.

    2017-03-01

    Context. Variability in the X-rays is a key ingredient in understanding and unveiling active galactic nuclei (AGN) properties. In this band, flux variations occur on short timescales (hours) as well as on larger timescales. While short timescale variability is often investigated in single source studies, only a few works are able to explore flux variation on very long timescales. Aims: This work aims to provide a statistical analysis of the AGN long term X-ray variability. We study variability on the largest time interval ever investigated for the 0.2-2 keV band, up to approximately 20 yr rest-frame for a sample of 220 sources. Moreover, we study variability for 2700 quasars up to approximatley eight years rest-frame in the same (soft) band. Methods: We built our source sample using the 3XMM serendipitous source catalogue data release 5, and data from ROSAT All Sky Survey Bright and Faint source catalogues. To ensure that we selected AGN only, we used the Sloan Digital Sky Survey quasar catalogues data releases 7 and 12. Combining ROSAT and XMM-Newton observations, we investigated variability using the structure function analysis which describes the amount of variability as a function of the lag between the observations. Results: Our work shows an increase of the structure function up to 20 yr. We find no evidence of a plateau in the structure function on these long timescales. Conclusions: The increase of the structure function at long time lags suggests that variability in the soft X-rays can be influenced by flux variations originated in the accretion disk or that they take place in a region large enough to justify variation on such long timescales.

  11. Quantum Monte Carlo estimation of complex-time correlations for the study of the ground-state dynamic structure function.

    PubMed

    Rota, R; Casulleras, J; Mazzanti, F; Boronat, J

    2015-03-21

    We present a method based on the path integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex variable whose phase δ acts as an adjustable parameter. By using high-order approximations for the quantum propagator, it is possible to obtain Monte Carlo data all the way from purely imaginary time to δ values near the limit of real time. As a consequence, it is possible to infer accurately the spectral functions using simple inversion algorithms. We test this approach in the calculation of the dynamic structure function S(q, ω) of two one-dimensional model systems, harmonic and quartic oscillators, for which S(q, ω) can be exactly calculated. We notice a clear improvement in the calculation of the dynamic response with respect to the common approach based on the inverse Laplace transform of the imaginary-time correlation function.

  12. Quantum Monte Carlo estimation of complex-time correlations for the study of the ground-state dynamic structure function

    NASA Astrophysics Data System (ADS)

    Rota, R.; Casulleras, J.; Mazzanti, F.; Boronat, J.

    2015-03-01

    We present a method based on the path integral Monte Carlo formalism for the calculation of ground-state time correlation functions in quantum systems. The key point of the method is the consideration of time as a complex variable whose phase δ acts as an adjustable parameter. By using high-order approximations for the quantum propagator, it is possible to obtain Monte Carlo data all the way from purely imaginary time to δ values near the limit of real time. As a consequence, it is possible to infer accurately the spectral functions using simple inversion algorithms. We test this approach in the calculation of the dynamic structure function S(q, ω) of two one-dimensional model systems, harmonic and quartic oscillators, for which S(q, ω) can be exactly calculated. We notice a clear improvement in the calculation of the dynamic response with respect to the common approach based on the inverse Laplace transform of the imaginary-time correlation function.

  13. The microvascular effects of insulin resistance and diabetes on cardiac structure, function, and perfusion: a cardiovascular magnetic resonance study

    PubMed Central

    Larghat, Abdulghani M.; Swoboda, Peter P.; Biglands, John D.; Kearney, Mark T.; Greenwood, John P.; Plein, Sven

    2014-01-01

    Aims Type 2 diabetes mellitus is an independent risk factor for the development of heart failure. To better understand the mechanism by which this occurs, we investigated cardiac structure, function, and perfusion in patients with and without diabetes. Methods and results Sixty-five patients with no stenosis >30% on invasive coronary angiography were categorized into diabetes (19) and non-diabetes (46) which was further categorized into prediabetes (30) and controls (16) according to the American Diabetes Association guidelines. Each patient underwent comprehensive cardiovascular magnetic resonance assessment. Left-ventricular (LV) mass, relative wall mass (RWM), Lagrangian circumferential strain, LV torsion, and myocardial perfusion reserve (MPR) were calculated. LV mass was higher in diabetics than non-diabetics (112.8 ± 39.7 vs. 91.5 ± 21.3 g, P = 0.01) and in diabetics than prediabetics (112.8 ± 39.7 vs. 90.3 ± 18.7 g, P = 0.02). LV torsion angle was higher in diabetics than non-diabetics (9.65 ± 1.90 vs. 8.59 ± 1.91°, P = 0.047), and MPR was lower in diabetics than non-diabetics (2.10 ± 0.76 vs. 2.84 ± 1.25 mL/g/min, P = 0.01). There was significant correlation between MPR and early diastolic strain rate (r = −0.310, P = 0.01) and LV torsion (r = −0.306, P = 0.01). In multivariable linear regression analysis, non-diabetics waist–hip ratio, but not body mass index, had a significant association with RWM (Beta = 0.34, P = 0.02). Conclusion Patients with diabetes have increased LV mass, LV torsion, and decreased MPR. There is a significant association between decreased MPR and increased LV torsion suggesting a possible mechanistic link between microvascular disease and cardiac dysfunction in diabetes. PMID:25117473

  14. LONG TERM IN SITU DISPOSAL ENGINEERING STUDY

    SciTech Connect

    ADAMS; CARLSON; BROCKMAN

    2003-07-23

    Patent application pulled per Ken Norris (FH General Counsel). The objective of this study is to devise methods, produce conceptual designs, examine and select alternatives, and estimate costs for the demonstration of long-term (300-year) in situ disposal of an existing waste disposal site. The demonstration site selected is the 216-A-24 Crib near the 200 East Area. The site contains a fission product inventory and has experienced plant, animal, and inadvertent than intrusion. Of the potential intrusive events and transport pathways at the site, potential human intrusion has been given primary consideration in barrier design. Intrusion by wind, plants, and animals has been given secondary consideration. Groundwater modeling for a number of barrier configurations has been carried out to help select a barrier that will minimize water infiltration and waste/water contact time. The estimated effective lifetime and cost of 20 barrier schemes, using a variety of materials, have been evaluated. The schemes studied include single component surface barriers, multicomponent barriers, and massively injected grout barriers. Five barriers with high estimated effective lifetimes and relatively low costs have been selected for detailed evaluation. They are basalt riprap barriers, massive soil barriers, salt basin barriers, multi-component fine/coarse barriers, and cemented basalt barriers. A variety of materials and configurations for marking the site have also been considered. A decision analysis was completed to select a barrier scheme for demonstration. The analysis indicated that the basalt riprap alternative would be the preferred choice for a full-scale demonstration. The recommended approach is to demonstrate the basalt riprap barrier at the 216-A-24 Crib as soon as possible. Methods and costs of assessing effectiveness of the demonstration are also described. Preliminary design modifications and costs for applying the five selected barrier schemes to other site types are

  15. Comparative Study on Sequence-Structure-Function Relationship of the Human Short-chain Dehydrogenases/Reductases Protein Family.

    PubMed

    Tang, Nu Thi Ngoc; Le, Ly

    2014-01-01

    Human short-chain dehydrogenases/reductases (SDRs) protein family has been the subject of recent studies for its critical role in human metabolism. Studies also found that single nucleotide polymorphisms of the SDR protein family were responsible for a variety of genetic diseases, including type II diabetes. This study reports the effect of sequence variation on the structural and functional integrities of human SDR protein family using phylogenetics and correlated mutation analysis tools. Our results indicated that (i) tyrosine, serine, and lysine are signature protein residues that have direct contribution to the structural and functional stabilities of the SDR protein family, (ii) subgroups of SDR protein family have their own signature protein combination that represent their unique functionality, and (iii) mutations of the human SDR protein family showed high correlation in terms of evolutionary history. In combination, the results inferred that over evolutionary history, the SDR protein family was able to diverge itself in order to adapt with the changes in human nutritional demands. Our study reveals understanding of structural and functional scaffolds of specific SDR subgroups that may facilitate the design of specific inhibitor.

  16. Identification of berberine as a direct thrombin inhibitor from traditional Chinese medicine through structural, functional and binding studies.

    PubMed

    Wang, Xing; Zhang, Yuxin; Yang, Ying; Wu, Xia; Fan, Hantian; Qiao, Yanjiang

    2017-03-09

    Thrombin acts as a key enzyme in the blood coagulation cascade and represents a potential drug target for the treatment of several cardiovascular diseases. The aim of this study was to identify small-molecule direct thrombin inhibitors from herbs used in traditional Chinese medicine (TCM). A pharmacophore model and molecular docking were utilized to virtually screen a library of chemicals contained in compositions of traditional Chinese herbs, and these analyses were followed by in vitro bioassay validation and binding studies. Berberine (BBR) was first confirmed as a thrombin inhibitor using an enzymatic assay. The BBR IC50 value for thrombin inhibition was 2.92 μM. Direct binding studies using surface plasmon resonance demonstrated that BBR directly interacted with thrombin with a KD value of 16.39 μM. Competitive binding assay indicated that BBR could bind to the same argartroban/thrombin interaction site. A platelet aggregation assay demonstrated that BBR had the ability to inhibit thrombin-induced platelet aggregation in washed platelets samples. This study proved that BBR is a direct thrombin inhibitor that has activity in inhibiting thrombin-induced platelet aggregation. BBR may be a potential candidate for the development of safe and effective thrombin-inhibiting drugs.

  17. Identification of berberine as a direct thrombin inhibitor from traditional Chinese medicine through structural, functional and binding studies

    NASA Astrophysics Data System (ADS)

    Wang, Xing; Zhang, Yuxin; Yang, Ying; Wu, Xia; Fan, Hantian; Qiao, Yanjiang

    2017-03-01

    Thrombin acts as a key enzyme in the blood coagulation cascade and represents a potential drug target for the treatment of several cardiovascular diseases. The aim of this study was to identify small-molecule direct thrombin inhibitors from herbs used in traditional Chinese medicine (TCM). A pharmacophore model and molecular docking were utilized to virtually screen a library of chemicals contained in compositions of traditional Chinese herbs, and these analyses were followed by in vitro bioassay validation and binding studies. Berberine (BBR) was first confirmed as a thrombin inhibitor using an enzymatic assay. The BBR IC50 value for thrombin inhibition was 2.92 μM. Direct binding studies using surface plasmon resonance demonstrated that BBR directly interacted with thrombin with a KD value of 16.39 μM. Competitive binding assay indicated that BBR could bind to the same argartroban/thrombin interaction site. A platelet aggregation assay demonstrated that BBR had the ability to inhibit thrombin-induced platelet aggregation in washed platelets samples. This study proved that BBR is a direct thrombin inhibitor that has activity in inhibiting thrombin-induced platelet aggregation. BBR may be a potential candidate for the development of safe and effective thrombin-inhibiting drugs.

  18. Identification of berberine as a direct thrombin inhibitor from traditional Chinese medicine through structural, functional and binding studies

    PubMed Central

    Wang, Xing; Zhang, Yuxin; Yang, Ying; Wu, Xia; Fan, Hantian; Qiao, Yanjiang

    2017-01-01

    Thrombin acts as a key enzyme in the blood coagulation cascade and represents a potential drug target for the treatment of several cardiovascular diseases. The aim of this study was to identify small-molecule direct thrombin inhibitors from herbs used in traditional Chinese medicine (TCM). A pharmacophore model and molecular docking were utilized to virtually screen a library of chemicals contained in compositions of traditional Chinese herbs, and these analyses were followed by in vitro bioassay validation and binding studies. Berberine (BBR) was first confirmed as a thrombin inhibitor using an enzymatic assay. The BBR IC50 value for thrombin inhibition was 2.92 μM. Direct binding studies using surface plasmon resonance demonstrated that BBR directly interacted with thrombin with a KD value of 16.39 μM. Competitive binding assay indicated that BBR could bind to the same argartroban/thrombin interaction site. A platelet aggregation assay demonstrated that BBR had the ability to inhibit thrombin-induced platelet aggregation in washed platelets samples. This study proved that BBR is a direct thrombin inhibitor that has activity in inhibiting thrombin-induced platelet aggregation. BBR may be a potential candidate for the development of safe and effective thrombin-inhibiting drugs. PMID:28276481

  19. Structure-Function Studies of Blood and Air Capillaries in Chicken Lung Using 3D Electron Microscopy

    PubMed Central

    West, John B.; Fu, Zhenxing; Deerinck, Thomas J.; Mackey, Mason R.; Obayashi, James T.; Ellisman, Mark H.

    2010-01-01

    Avian pulmonary capillaries differ from those of mammals in three important ways. The blood-gas barrier is much thinner, it is more uniform in thickness, and the capillaries are far more rigid when their transmural pressure is altered. The thinness of the barrier is surprising because it predisposes the capillaries to stress failure. A possible mechanism for these differences is that avian pulmonary capillaries, unlike mammalian, are supported from the outside by air capillaries, but the details of the support are poorly understood. To clarify this we studied the blood and air capillaries in chicken lung using transmission electron microscopy (EM) and two relatively new techniques that allow 3D visualization: electron tomography and serial block-face scanning EM. These studies show that the pulmonary capillaries are flanked by epithelial bridges composed of two extremely thin epithelial cells with large surface areas. The junctions of the bridges with the capillary walls show thickening of the epithelial cells and an accumulation of extracellular matrix. Collapse of the pulmonary capillaries when the pressure outside them is increased is apparently prevented by the guy wire-like action of the epithelial bridges. The enlarged junctions between the bridges and the walls could provide a mechanism that limits the hoop stress in the capillary walls when the pressure inside them is increased. The support of the pulmonary capillaries may also be explained by an interdependence mechanism whereby the capillaries are linked to a rigid assemblage of air capillaries. These EM studies show the supporting structures in greater detail than has previously been possible, particularly in 3D, and they allow a more complete analysis of the mechanical forces affecting avian pulmonary capillaries. PMID:20038456

  20. Structure-function study of gemini derivatives with two different side chains at C-20, Gemini-0072 and Gemini-0097.

    PubMed

    Huet, Tiphaine; Maehr, Hubert; Lee, Hong Jin; Uskokovic, Milan R; Suh, Nanjoo; Moras, Dino; Rochel, Natacha

    2011-01-01

    Derivatives of vitamin D(3) containing a second side-chain emanating at C-20 are known as gemini and act as vitamin D receptor agonists. Recently, two of these, namely Gemini-0072 and the epimeric Gemini-0097, were selected for further studies in view of their high biological activities and lack of hypercalcemic effects. We now show that the two analogs recruit coactivator SRC-1 better than the parental gemini and act as VDR superagonists. The crystal structures of complexes of zVDR with Gemini-0072 and Gemini-0097 indicate that these ligands induce an extra cavity within the ligand-binding pocket similar to gemini and that their superagonistic activity is due to an increased stabilization of helix H12.

  1. Structure-function Studies of Nucleocytoplasmic Transport of Retroviral Genomic RNA by mRNA Export Factor TAP

    SciTech Connect

    M Teplova; L Wohlbold; N Khin; E Izaurralde; D Patel

    2011-12-31

    mRNA export is mediated by the TAP-p15 heterodimer, which belongs to the family of NTF2-like export receptors. TAP-p15 heterodimers also bind to the constitutive transport element (CTE) present in simian type D retroviral RNAs, and they mediate the export of viral unspliced RNAs to the host cytoplasm. We have solved the crystal structure of the RNA recognition and leucine-rich repeat motifs of TAP bound to one symmetrical half of the CTE RNA. L-shaped conformations of protein and RNA are involved in a mutual molecular embrace on complex formation. We have monitored the impact of structure-guided mutations on binding affinities in vitro and transport assays in vivo. Our studies define the principles by which CTE RNA subverts the mRNA export receptor TAP, thereby facilitating the nuclear export of viral genomic RNAs, and, more generally, provide insights on cargo RNA recognition by mRNA export receptors.

  2. Structure-Function Studies of Escherichia coli RpoH (σ32) by In Vitro Linker Insertion Mutagenesis

    PubMed Central

    Narberhaus, Franz; Balsiger, Sylvia

    2003-01-01

    The sigma factor RpoH (σ32) is the key regulator of the heat shock response in Escherichia coli. Many structural and functional properties of the sigma factor are poorly understood. To gain further insight into RpoH regions that are either important or dispensable for its cellular activity, we generated a collection of tetrapeptide insertion variants by a recently established in vitro linker insertion mutagenesis technique. Thirty-one distinct insertions were obtained, and their sigma factor activity was analyzed by using a groE-lacZ reporter fusion in an rpoH-negative background. Our study provides a map of permissive sites which tolerate linker insertions and of functionally important regions at which a linker insertion impairs sigma factor activity. Selected linker insertion mutants will be discussed in the light of known sigma factor properties and in relation to a modeled structure of an RpoH fragment containing region 2. PMID:12700252

  3. Structure-function studies of Escherichia coli RpoH (sigma32) by in vitro linker insertion mutagenesis.

    PubMed

    Narberhaus, Franz; Balsiger, Sylvia

    2003-05-01

    The sigma factor RpoH (sigma(32)) is the key regulator of the heat shock response in Escherichia coli. Many structural and functional properties of the sigma factor are poorly understood. To gain further insight into RpoH regions that are either important or dispensable for its cellular activity, we generated a collection of tetrapeptide insertion variants by a recently established in vitro linker insertion mutagenesis technique. Thirty-one distinct insertions were obtained, and their sigma factor activity was analyzed by using a groE-lacZ reporter fusion in an rpoH-negative background. Our study provides a map of permissive sites which tolerate linker insertions and of functionally important regions at which a linker insertion impairs sigma factor activity. Selected linker insertion mutants will be discussed in the light of known sigma factor properties and in relation to a modeled structure of an RpoH fragment containing region 2.

  4. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures

    PubMed Central

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-01-01

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires. PMID:27571919

  5. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures.

    PubMed

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-08-30

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires.

  6. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures

    NASA Astrophysics Data System (ADS)

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-08-01

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires.

  7. In Situ and Ex Situ TEM Study of Lithiation Behaviours of Porous Silicon Nanostructures

    SciTech Connect

    Shen, Chenfei; Ge, Mingyuan; Luo, Langli; Fang, Xin; Liu, Yihang; Zhang, Anyi; Rong, Jiepeng; Wang, Chongmin; Zhou, Chongwu

    2016-08-30

    In this work, we study the lithiation behaviours of both porous silicon (Si) nanoparticles and porous Si nanowires by in situ and ex situ transmission electron microscopy (TEM) and compare them with solid Si nanoparticles and nanowires. The in situ TEM observation reveals that the critical fracture diameter of porous Si particles reaches up to 1.52 μm, which is much larger than the previously reported 150 nm for crystalline Si nanoparticles and 870 nm for amorphous Si nanoparticles. After full lithiation, solid Si nanoparticles and nanowires transform to crystalline Li15Si4 phase while porous Si nanoparticles and nanowires transform to amorphous LixSi phase, which is due to the effect of domain size on the stability of Li15Si4 as revealed by the first-principle molecular dynamic simulation. Ex situ TEM characterization is conducted to further investigate the structural evolution of porous and solid Si nanoparticles during the cycling process, which confirms that the porous Si nanoparticles exhibit better capability to suppress pore evolution than solid Si nanoparticles. The investigation of structural evolution and phase transition of porous Si nanoparticles and nanowires during the lithiation process reveal that they are more desirable as lithium-ion battery anode materials than solid Si nanoparticles and nanowires.

  8. Structure-function studies of STAR family Quaking proteins bound to their in vivo RNA target sites

    SciTech Connect

    Teplova, Marianna; Hafner, Markus; Teplov, Dmitri; Essig, Katharina; Tuschl, Thomas; Patel, Dinshaw J.

    2013-09-27

    Mammalian Quaking (QKI) and its Caenorhabditis elegans homolog, GLD-1 (defective in germ line development), are evolutionarily conserved RNA-binding proteins, which post-transcriptionally regulate target genes essential for developmental processes and myelination. We present X-ray structures of the STAR (signal transduction and activation of RNA) domain, composed of Qua1, K homology (KH), and Qua2 motifs of QKI and GLD-1 bound to high-affinity in vivo RNA targets containing YUAAY RNA recognition elements (RREs). The KH and Qua2 motifs of the STAR domain synergize to specifically interact with bases and sugar-phosphate backbones of the bound RRE. Qua1-mediated homodimerization generates a scaffold that enables concurrent recognition of two RREs, thereby plausibly targeting tandem RREs present in many QKI-targeted transcripts. Structure-guided mutations reduced QKI RNA-binding affinity in vitro and in vivo, and expression of QKI mutants in human embryonic kidney cells (HEK293) significantly decreased the abundance of QKI target mRNAs. Overall, our studies define principles underlying RNA target selection by STAR homodimers and provide insights into the post-transcriptional regulatory function of mammalian QKI proteins.

  9. Foam fractionation as a tool to study the air-water interface structure-function relationship of wheat gluten hydrolysates.

    PubMed

    Wouters, Arno G B; Rombouts, Ine; Schoebrechts, Nele; Fierens, Ellen; Brijs, Kristof; Blecker, Christophe; Delcour, Jan A

    2017-03-01

    Enzymatic hydrolysis of wheat gluten protein improves its solubility and produces hydrolysates with foaming properties which may find applications in food products. First, we here investigated whether foam-liquid fractionation can concentrate wheat gluten peptides with foaming properties. Foam and liquid fractions had high and very low foam stability (FS), respectively. In addition, foam fractions were able to decrease surface tension more pronouncedly than un-fractionated samples and liquid fractions, suggesting they are able to arrange themselves more efficiently at an interface. As a second objective, foam fractionation served as a tool to study the structural properties of the peptides, causing these differences in air-water interfacial behavior. Zeta potential and surface hydrophobicity measurements did not fully explain these differences but suggested that hydrophobic interactions at the air-water interface are more important than electrostatic interactions. RP-HPLC showed a large overlap between foam and liquid fractions. However, a small fraction of very hydrophobic peptides with relatively high average molecular mass was clearly enriched in the foam fraction. These peptides were also more concentrated in un-fractionated DH 2 hydrolysates, which had high FS, than in DH 6 hydrolysates, which had low FS. These peptides most likely play a key role in stabilizing the air-water interface.

  10. Structure, function and management of semi-natural habitats for conservation biological control: a review of European studies.

    PubMed

    Holland, John M; Bianchi, Felix Jja; Entling, Martin H; Moonen, Anna-Camilla; Smith, Barbara M; Jeanneret, Philippe

    2016-09-01

    Different semi-natural habitats occur on farmland, and it is the vegetation's traits and structure that subsequently determine their ability to support natural enemies and their associated contribution to conservation biocontrol. New habitats can be created and existing ones improved with agri-environment scheme funding in all EU member states. Understanding the contribution of each habitat type can aid the development of conservation control strategies. Here we review the extent to which the predominant habitat types in Europe support natural enemies, whether this results in enhanced natural enemy densities in the adjacent crop and whether this leads to reduced pest densities. Considerable variation exists in the available information for the different habitat types and trophic levels. Natural enemies within each habitat were the most studied, with less information on whether they were enhanced in adjacent fields, while their impact on pests was rarely investigated. Most information was available for woody and herbaceous linear habitats, yet not for woodland which can be the most common semi-natural habitat in many regions. While the management and design of habitats offer potential to stimulate conservation biocontrol, we also identified knowledge gaps. A better understanding of the relationship between resource availability and arthropod communities across habitat types, the spatiotemporal distribution of resources in the landscape and interactions with other factors that play a role in pest regulation could contribute to an informed management of semi-natural habitats for biocontrol. © 2016 Society of Chemical Industry.

  11. Synthesis and structure-function study about tenecin 1, an antibacterial protein from larvae of Tenebrio molitor.

    PubMed

    Lee, K H; Hong, S Y; Oh, J E

    1998-11-13

    Tenecin 1, an inducible antibacterial protein secreted in the larvae of Tenebrio molitor, has a long N-terminal loop and common structural feature of insect defensin family corresponding to cysteine stabilized alpha/beta motif. To study the function of the N-terminal loop and disulfide bridges, N-terminal loop deleted tenecin 1, reduced tenecin 1 and tenecin 1 were chemically synthesized and their activities were measured. N-terminal loop deleted tenecin and reduced tenecin 1 did not show antibacterial activity. Circular dichroism (CD) spectroscopy data revealed that the alpha-helical content of tenecin 1 and the other proteins increased in the presence of 50% (v/v) trifluoroethanol (TFE) and the alpha-helical content of tenecin 1 was much higher than that of the other proteins in buffer with or without 50% (v/v) TFE. These results suggest that disulfide bridges are necessary for the activity structure and the N-terminal loop plays an important role in the increase of alpha-helix in the membrane mimetic environment and the activity.

  12. Structure-function relationship of the plant photosynthetic pigment-protein complex LHCII studied with molecular spectroscopy techniques.

    PubMed

    Gruszecki, Wieslaw I

    2013-01-01

    LHCII, the largest plant photosynthetic pigment-protein complex of photosystem II, is a most abundant membrane protein in living organisms and comprises approximately half of the pool of chlorophyll molecules in the biosphere. The principal role of this pigment-protein complex is to collect sunlight quanta and transfer electronic excitations toward the reaction centers, where the primary photosynthetic electric charge separation reactions take place. The LHCII protein, as a major protein component of the photosynthetic membranes, modulates also the structural and dynamic properties of the lipid phase of the membranes. According to the recent concepts, one of the physiological roles of LHCII is also a protection of the photosynthetic apparatus against oxidative damage caused by illumination with high intensity light. Detailed examination of all those physiological functions of LHCII, in relation to the complex structure, was possible owing to the application of several molecular spectroscopy techniques. Some examples of such studies are presented in this chapter. The examples of application of steady-state and time-resolved fluorescence spectroscopy, Fourier-transform infrared absorption spectroscopy, and resonance Raman scattering spectroscopy are presented and discussed.

  13. Bactericidal activity identified in 2S Albumin from sesame seeds and in silico studies of structure-function relations.

    PubMed

    Maria-Neto, Simone; Honorato, Rodrigo V; Costa, Fábio T; Almeida, Renato G; Amaro, Daniel S; Oliveira, José T A; Vasconcelos, Ilka M; Franco, Octávio L

    2011-06-01

    Pathogenic bacteria constitute an important cause of hospital-acquired infections. However, the misuse of available bactericidal agents has led to the appearance of antibiotic-resistant strains. Thus, efforts to seek new antimicrobials with different action mechanisms would have an enormous impact. Here, a novel antimicrobial protein (SiAMP2) belonging to the 2S albumin family was isolated from Sesamum indicum kernels and evaluated against several bacteria and fungi. Furthermore, in silico analysis was conducted in order to identify conserved residues through other 2S albumin antimicrobial proteins (2S-AMPs). SiAMP2 specifically inhibited Klebsiella sp. Specific regions in the molecule surface where cationic (RR/RRRK) and hydrophobic (MEYWPR) residues are exposed and conserved were proposed as being involved in antimicrobial activity. This study reinforces the hypothesis that plant storage proteins might also play as pathogen protection providing an insight into the mechanism of action for this novel 2S-AMP and evolutionary relations between antimicrobial activity and 2S albumins.

  14. Structure Function Studies of Vaccinia Virus Host Range Protein K1 Reveal a Novel Functional Surface for Ankyrin Repeat Proteins

    SciTech Connect

    Li, Yongchao; Meng, Xiangzhi; Xiang, Yan; Deng, Junpeng

    2010-06-15

    Poxvirus host tropism at the cellular level is regulated by virus-encoded host range proteins acting downstream of virus entry. The functioning mechanisms of most host range proteins are unclear, but many contain multiple ankyrin (ANK) repeats, a motif that is known for ligand interaction through a concave surface. We report here the crystal structure of one of the ANK repeat-containing host range proteins, the vaccinia virus K1 protein. The structure, at a resolution of 2.3 {angstrom}, showed that K1 consists entirely of ANK repeats, including seven complete ones and two incomplete ones, one each at the N and C terminus. Interestingly, Phe82 and Ser83, which were previously shown to be critical for K1's function, are solvent exposed and located on a convex surface, opposite the consensus ANK interaction surface. The importance of this convex surface was further supported by our additional mutagenesis studies. We found that K1's host range function was negatively affected by substitution of either Asn51 or Cys47 and completely abolished by substitution of both residues. Cys47 and Asn51 are also exposed on the convex surface, spatially adjacent to Phe82 and Ser83. Altogether, our data showed that K1 residues on a continuous convex ANK repeat surface are critical for the host range function, suggesting that K1 functions through ligand interaction and does so with a novel ANK interaction surface.

  15. Structure-function studies of HNF1A (MODY3) gene mutations in South Indian patients with monogenic diabetes.

    PubMed

    Balamurugan, K; Bjørkhaug, L; Mahajan, S; Kanthimathi, S; Njølstad, P R; Srinivasan, N; Mohan, V; Radha, V

    2016-12-01

    Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous monogenic form of diabetes characterized by onset of diabetes below 25 years of age, autosomal dominant mode of inheritance and primary defect in insulin secretion. Mutations in the gene (HNF1A) encoding transcription factor hepatocyte nuclear factor 1A (HNF-1A) results in one of the most common forms of MODY (MODY3). HNF-1A is mainly enriched in pancreatic β-cells and hepatocytes and important for organ development and normal pancreatic function. We here report on the functional interrogation of eight missense HNF1A mutations associated with MODY3 in South Indian subjects, and the contributing effect of common variant (S487N) within HNF1A. Of the eight mutations, three mutations (p.R171G, p.G245R and p.R263H), in particular, affected HNF-1A function in transfected HeLa cells by reducing both transcriptional activity and nuclear localization, possibly due to disruption of the integrity of the three dimensional structure. The common variant p.S487N contributed further to the loss-of-function of p.R271Q (p.R271Q+p.S487N double mutant), in vitro, on both activity and localization. Our data on the first functional study of HNF1A mutations in South India subjects confers that the defect of the HNF-1A mutant proteins are responsible for MODY3 diabetes in these patients.

  16. Catalytic mechanism and substrate selectivity of aldo-keto reductases: insights from structure-function studies of Candida tenuis xylose reductase.

    PubMed

    Kratzer, Regina; Wilson, David K; Nidetzky, Bernd

    2006-09-01

    Aldo-keto reductases (AKRs) constitute a large protein superfamily of mainly NAD(P)-dependent oxidoreductases involved in carbonyl metabolism. Catalysis is promoted by a conserved tetrad of active site residues (Tyr, Lys, Asp and His). Recent results of structure-function relationship studies for xylose reductase (AKR2B5) require an update of the proposed catalytic mechanism. Electrostatic stabilization by the epsilon-NH3+ group of Lys is a key source of catalytic power of xylose reductase. A molecular-level analysis of the substrate binding pocket of xylose reductase provides a case of how a very broadly specific AKR achieves the requisite selectivity for its physiological substrate and could serve as the basis for the design of novel reductases with improved specificities for biocatalytic applications.

  17. Proton structure functions at HERA

    NASA Astrophysics Data System (ADS)

    Abt, Iris

    2014-05-01

    The "proton structure" is a wide field. Discussed are predominantly the precision measurements of the proton structure functions at HERA and some of their implications for the LHC measurements. In addition, a discussion of what a proton structure function represents is provided. Finally, a connection to nuclear physics is attempted. This contribution is an updated reprint of a contribution to "Deep Inelastic Scattering 2012".1

  18. Defining the Interactions of Cellobiohydrolase with Substrate through Structure Function Studies: Cooperative Research and Development Final Report, CRADA Number CRD-10-409

    SciTech Connect

    Beckham, G. T.; Himmel, M. E.

    2013-07-01

    NREL researchers will use their expertise and skilled resources in numerical computational modeling to generate structure-function relationships for improved cellulase variant enzymes to support the development of cellulases with improved performance in biomass conversion.

  19. In situ studies of solvothermal synthesis of energy materials.

    PubMed

    Jensen, Kirsten M Ø; Tyrsted, Christoffer; Bremholm, Martin; Iversen, Bo B

    2014-06-01

    Solvothermal and hydrothermal synthesis, that is, synthesis taking place in a solvent at elevated temperature and pressure, is a powerful technique for the production of advanced energy materials as it is versatile, cheap, and environmentally friendly. However, the fundamental reaction mechanisms dictating particle formation and growth under solvothermal conditions are not well understood. In order to produce tailor-made materials with specific properties for advanced energy technologies, it is essential to obtain an improved understanding of these processes and, in this context, in situ studies are an important tool as they provide real time information on the reactions taking place. Here, we present a review of the use of powder diffraction and total scattering methods for in situ studies of synthesis taking place under solvothermal and hydrothermal conditions. The experimental setups used for in situ X-ray and neutron studies are presented, and methods of data analysis are described. Special attention is given to the methods used to extract structural information from the data, for example, Rietveld refinement, whole powder pattern modelling and pair distribution function analysis. Examples of in situ studies are presented to illustrate the types of chemical insight that can be obtained.

  20. Chemical Library Screening and Structure-Function Relationship Studies Identify Bisacodyl as a Potent and Selective Cytotoxic Agent Towards Quiescent Human Glioblastoma Tumor Stem-Like Cells

    PubMed Central

    Mameri, Samir; Dong, Jihu; Salomé, Christophe; Chen, Wanyin; El-Habr, Elias A.; Bousson, Fanny; Sy, Mohamadou; Obszynski, Julie; Boh, Alexandre; Villa, Pascal; Assad Kahn, Suzana; Didier, Bruno; Bagnard, Dominique; Junier, Marie-Pierre; Chneiweiss, Hervé; Haiech, Jacques; Hibert, Marcel; Kilhoffer, Marie-Claude

    2015-01-01

    Cancer stem-like cells reside in hypoxic and slightly acidic tumor niches. Such microenvironments favor more aggressive undifferentiated phenotypes and a slow growing "quiescent state" which preserves them from chemotherapeutic agents that essentially target proliferating cells. Our objective was to identify compounds active on glioblastoma stem-like cells, including under conditions that mimick those found in vivo within this most severe and incurable form of brain malignancy. We screened the Prestwick Library to identify cytotoxic compounds towards glioblastoma stem-like cells, either in a proliferating state or in more slow-growing "quiescent" phenotype resulting from non-renewal of the culture medium in vitro. Compound effects were assessed by ATP-level determination using a cell-based assay. Twenty active molecules belonging to different pharmacological classes have thus been identified. Among those, the stimulant laxative drug bisacodyl was the sole to inhibit in a potent and specific manner the survival of quiescent glioblastoma stem-like cells. Subsequent structure-function relationship studies led to identification of 4,4'-dihydroxydiphenyl-2-pyridyl-methane (DDPM), the deacetylated form of bisacodyl, as the pharmacophore. To our knowledge, bisacodyl is currently the only known compound targeting glioblastoma cancer stem-like cells in their quiescent, more resistant state. Due to its known non-toxicity in humans, bisacodyl appears as a new potential anti-tumor agent that may, in association with classical chemotherapeutic compounds, participate in tumor eradication. PMID:26270679

  1. Altered structure-function relations of semantic processing in youths with high-functioning autism: a combined diffusion and functional MRI study.

    PubMed

    Lo, Yu-Chun; Chou, Tai-Li; Fan, Li-Ying; Gau, Susan Shur-Fen; Chiu, Yen-Nan; Tseng, Wen-Yih Isaac

    2013-12-01

    Deficits in language and communication are among the core symptoms of autism, a common neurodevelopmental disorder with long-term impairment. Despite the striking nature of the autistic language impairment, knowledge about its corresponding alterations in the brain is still evolving. We hypothesized that the dual stream language network is altered in autism, and that this alteration could be revealed by changes in the relationships between microstructural integrity and functional activation. The study recruited 20 right-handed male youths with autism and 20 carefully matched individually, typically developing (TD) youths. Microstructural integrity of the left dorsal and left ventral pathways responsible for language processing and the functional activation of the connected brain regions were investigated by using diffusion spectrum imaging and functional magnetic resonance imaging of a semantic task, respectively. Youths with autism had significantly poorer language function, and lower functional activation in left dorsal and left ventral regions of the language network, compared with TD youths. The TD group showed a significant correlation of the functional activation of the left dorsal region with microstructural integrity of the left ventral pathway, whereas the autism group showed a significant correlation of the functional activation of the left ventral region with microstructural integrity of the left dorsal pathway, and moreover verbal comprehension index was correlated with microstructural integrity of the left ventral pathway. These altered structure-function relationships in autism suggest possible involvement of the dual pathways in supporting deficient semantic processing.

  2. Chemical Library Screening and Structure-Function Relationship Studies Identify Bisacodyl as a Potent and Selective Cytotoxic Agent Towards Quiescent Human Glioblastoma Tumor Stem-Like Cells.

    PubMed

    Zeniou, Maria; Fève, Marie; Mameri, Samir; Dong, Jihu; Salomé, Christophe; Chen, Wanyin; El-Habr, Elias A; Bousson, Fanny; Sy, Mohamadou; Obszynski, Julie; Boh, Alexandre; Villa, Pascal; Assad Kahn, Suzana; Didier, Bruno; Bagnard, Dominique; Junier, Marie-Pierre; Chneiweiss, Hervé; Haiech, Jacques; Hibert, Marcel; Kilhoffer, Marie-Claude

    2015-01-01

    Cancer stem-like cells reside in hypoxic and slightly acidic tumor niches. Such microenvironments favor more aggressive undifferentiated phenotypes and a slow growing "quiescent state" which preserves them from chemotherapeutic agents that essentially target proliferating cells. Our objective was to identify compounds active on glioblastoma stem-like cells, including under conditions that mimick those found in vivo within this most severe and incurable form of brain malignancy. We screened the Prestwick Library to identify cytotoxic compounds towards glioblastoma stem-like cells, either in a proliferating state or in more slow-growing "quiescent" phenotype resulting from non-renewal of the culture medium in vitro. Compound effects were assessed by ATP-level determination using a cell-based assay. Twenty active molecules belonging to different pharmacological classes have thus been identified. Among those, the stimulant laxative drug bisacodyl was the sole to inhibit in a potent and specific manner the survival of quiescent glioblastoma stem-like cells. Subsequent structure-function relationship studies led to identification of 4,4'-dihydroxydiphenyl-2-pyridyl-methane (DDPM), the deacetylated form of bisacodyl, as the pharmacophore. To our knowledge, bisacodyl is currently the only known compound targeting glioblastoma cancer stem-like cells in their quiescent, more resistant state. Due to its known non-toxicity in humans, bisacodyl appears as a new potential anti-tumor agent that may, in association with classical chemotherapeutic compounds, participate in tumor eradication.

  3. Structure-Function Analysis of Porcine Cytochrome P450 3A29 in the Hydroxylation of T-2 Toxin as Revealed by Docking and Mutagenesis Studies

    PubMed Central

    Wang, Xu; Ma, Hongmin; Pan, Yuanhu; Huang, Lingli; Hao, Haihong; Dai, Menghong; Yuan, Zonghui

    2014-01-01

    T-2 toxin, one of the type A trichothecenes, presents a potential hazard to human and animal health. Our previous work demonstrated that porcine cytochrome P450 3A29 (CYP3A29) played an important role in the hydroxylation of T-2 toxin. To identify amino acids involved in this metabolic process, T-2 toxin was docked into a homology model of CYP3A29 based on a crystal structure of CYP3A4 using AutoDock 4.0. Nine residues of CYP3A29, Arg105, Arg106, Phe108, Ser119, Lys212, Phe213, Phe215, Arg372 and Glu374, which were found within 5 Å around T-2 toxin were subjected to site-directed mutagenesis. In the oxidation of nifedipine, the CLint value of R106A was increased by nearly two-folds compared with the wild-type CYP3A29, while the substrate affinities and CLint values of S119A and K212A were significantly reduced. In the hydroxylation of T-2 toxin, the generation of 3′-OH-T-2 by R105A, S119A and K212A was significantly less than that by the wild-type, whereas R106A slightly increased the generation of 3′-OH-T-2. These results were further confirmed by isothermal titration calorimetry analysis, suggesting that these four residues are important in the hydroxylation of T-2 toxin and Arg105 may be a specific recognition site for the toxin. Our study suggests a possible structure-function relationship of CYP3A29 in the hydroxylation of T-2 toxin, providing with new insights into the mechanism of CYP3A enzymes in the biotransformation of T-2 toxin. PMID:25184434

  4. Computational chemistry study of 3D-structure-function relationships for enzymes based on Markov models for protein electrostatic, HINT, and van der Waals potentials.

    PubMed

    Concu, Riccardo; Podda, Gianni; Uriarte, Eugenio; González-Díaz, Humberto

    2009-07-15

    In a significant work, Dobson and Doig (J Mol Biol 2003, 330, 771) illustrated protein prediction as enzymatic or not from spatial structure without resorting to alignments. They used 52 protein features and a nonlinear support vector machine model to classify more than 1000 proteins collected from the PDB with a 77% overall accuracy. The most useful features were: the secondary-structure content, the amino acid frequencies, the number of disulphide bonds, and the largest cleft size. Working on the same dataset used by D&D, in this article we reported a good and simple model, based on the Markov chain models (MCM), to classify protein 3D structures as enzymatic or not, taking into consideration the spatial structure without resorting to alignments. Here we define, for the first time, a general MCM to calculate the electrostatic potential, molecular vibrations, van der Waals (vdw) interactions, and hydrophobic interactions (HINT) and use them in comparative studies of potential fields and/or protein function prediction. The dataset is composed of 1371 proteins divided into 689 enzymes and 682 nonenzymes, all proteins were collected from the PDB. The best model we found was a linear model carried out with the linear discriminant analysis; it was able to classify 74.18% of the proteins using only two electrostatic potentials. In the work described here, we define 3D-HINT potentials (mu(k)) and use them for the first time to derive a classifier for protein enzymes. We analyzed ROC curves, domain of applicability, parametric assumptions, desirability maps, and also tested other nonlinear artificial neural network models which did not improve the linear model. In closing, this MCM allows a fast calculation and comparison of different potentials deriving into accurate protein 3D structure-function relationships, notably simpler than the previous.

  5. Underwater microscopy for in situ studies of benthic ecosystems.

    PubMed

    Mullen, Andrew D; Treibitz, Tali; Roberts, Paul L D; Kelly, Emily L A; Horwitz, Rael; Smith, Jennifer E; Jaffe, Jules S

    2016-07-12

    Microscopic-scale processes significantly influence benthic marine ecosystems such as coral reefs and kelp forests. Due to the ocean's complex and dynamic nature, it is most informative to study these processes in the natural environment yet it is inherently difficult. Here we present a system capable of non-invasively imaging seafloor environments and organisms in situ at nearly micrometre resolution. We overcome the challenges of underwater microscopy through the use of a long working distance microscopic objective, an electrically tunable lens and focused reflectance illumination. The diver-deployed instrument permits studies of both spatial and temporal processes such as the algal colonization and overgrowth of bleaching corals, as well as coral polyp behaviour and interspecific competition. By enabling in situ observations at previously unattainable scales, this instrument can provide important new insights into micro-scale processes in benthic ecosystems that shape observed patterns at much larger scales.

  6. Underwater microscopy for in situ studies of benthic ecosystems

    NASA Astrophysics Data System (ADS)

    Mullen, Andrew D.; Treibitz, Tali; Roberts, Paul L. D.; Kelly, Emily L. A.; Horwitz, Rael; Smith, Jennifer E.; Jaffe, Jules S.

    2016-07-01

    Microscopic-scale processes significantly influence benthic marine ecosystems such as coral reefs and kelp forests. Due to the ocean's complex and dynamic nature, it is most informative to study these processes in the natural environment yet it is inherently difficult. Here we present a system capable of non-invasively imaging seafloor environments and organisms in situ at nearly micrometre resolution. We overcome the challenges of underwater microscopy through the use of a long working distance microscopic objective, an electrically tunable lens and focused reflectance illumination. The diver-deployed instrument permits studies of both spatial and temporal processes such as the algal colonization and overgrowth of bleaching corals, as well as coral polyp behaviour and interspecific competition. By enabling in situ observations at previously unattainable scales, this instrument can provide important new insights into micro-scale processes in benthic ecosystems that shape observed patterns at much larger scales.

  7. Underwater microscopy for in situ studies of benthic ecosystems

    PubMed Central

    Mullen, Andrew D.; Treibitz, Tali; Roberts, Paul L. D.; Kelly, Emily L. A.; Horwitz, Rael; Smith, Jennifer E.; Jaffe, Jules S.

    2016-01-01

    Microscopic-scale processes significantly influence benthic marine ecosystems such as coral reefs and kelp forests. Due to the ocean's complex and dynamic nature, it is most informative to study these processes in the natural environment yet it is inherently difficult. Here we present a system capable of non-invasively imaging seafloor environments and organisms in situ at nearly micrometre resolution. We overcome the challenges of underwater microscopy through the use of a long working distance microscopic objective, an electrically tunable lens and focused reflectance illumination. The diver-deployed instrument permits studies of both spatial and temporal processes such as the algal colonization and overgrowth of bleaching corals, as well as coral polyp behaviour and interspecific competition. By enabling in situ observations at previously unattainable scales, this instrument can provide important new insights into micro-scale processes in benthic ecosystems that shape observed patterns at much larger scales. PMID:27403715

  8. Structure functions and parton distributions

    SciTech Connect

    Martin, A.D.; Stirling, W.J.; Roberts, R.G.

    1995-07-01

    The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.

  9. A structure-function study of PACAP using conformationally-restricted analogs: identification of PAC1 receptor-selective PACAP agonists

    PubMed Central

    Ramos-Álvarez, Irene; Mantey, Samuel A.; Nakamura, Taichi; Nuche-Berenguer, Bernardo; Moreno, Paola; Moody, Terry W.; Maderdrut, Jerome L.; Coy, David H.; Jensen, Robert T.

    2015-01-01

    Pituitary adenylate-cyclase-activating polypeptide (PACAP) has widespread physiological/pathophysiological actions and there is increased interest for its use therapeutically, especially in the CNS (neuroprotection). Unfortunately, no selective PACAP-analogs exist for PACAP-preferring PAC1-receptors, primarily because of its high sequence identity to VIP and particularly, because of the inability of structure-function studies to separate the pharmacophore of PAC1-R from VPAC1-R, which has high affinity for PACAP and VIP. The present study attempted to develop PAC1-R-selective agonists primarily by making conformationally-restricted PACAP -analogs in positions important for receptor-selectivity/affinity. Forty-six PACAP-related-analogs were synthesized with substitutions in positions 1–4, 14–17, 20–22 ,28,34,38 and receptor-selectivity determined in PAC1-R,VPAC1-R,VPAC2-R-transfected or native cells from binding or cAMP-generation experiments. Fifteen PACAP-analogs had 6–78-fold higher affinities for PAC1-R than VPAC1-R and 13 were agonists. Although binding-affinities correlated significantly with agonist potency, the degree of receptor-spareness varied markedly for the different PACAP-analogs, resulting in selective potencies for activating the PAC1 receptor over the VPAC1 receptor from 0- to-103-fold. In addition, a number of PACAP-analogs were identified that had high selectivity for PAC1-R over VPAC2-R as well as PACAP-analogs that could prove more useful therapeutically because of substitutions known to extend their half-lives (substitutions at potential sites of proteolysis and attachment of long-chain fatty acids). This study provides for the first time a separation of the pharmacophores for PAC1-R and VPAC1-R, resulting in PACAP-related analogs that are PAC1-R-preferring. Some of these analogs, or their modifications, could prove useful as therapeutic agents for various diseases. PMID:25698233

  10. Mapping of structure-function relationships in proteins with a panel of monoclonal antibodies. A study on human alpha 2 macroglobulin.

    PubMed

    Van Leuven, F; Marynen, P; Cassiman, J J; Van den Berghe, H

    1988-06-28

    Monoclonal antibody (Mab) F2B2, directed to the receptor-recognition site of human alpha 2 macroglobulin (alpha 2M), has been instrumental in the characterization of that site and in the isolation of the receptor-binding domain. We have now prepared a panel of Mab to study the structure-function relationships in alpha 2 M, and in particular the expression of the receptor-recognition site. Reversed dot-blotting was very effective to screen hybridoma supernatant for specificities to either the native or complex form of alpha 2M. Reaction with the isolated 20 kDa receptor-binding domain of alpha 2M and cross-reaction with pregnancy zone protein was detected by the same technique. Eventually, a panel of 45 Mab was constructed consisting of essentially five types of specificities, although in fact no two Mab reacted with complete identity in all assays. In addition to the assays already mentioned, the Mab were tested for interference with binding of alpha 2M-trypsin to the cellular receptor, for competition with F2B2 for alpha 2M-trypsin and for inhibition of trypsin by alpha 2M. Finally, Western blotting was used as a first approximate mapping of the epitope relative to the internal thiolesters by exploiting the heat-induced fragmentation of alpha 2M at this site. The five categories of Mab thus detected were: (i) five Mab that react with native alpha 2M and not with alpha 2M trypsin; (ii) 18 Mab that react with both native alpha 2M and with alpha 2M-trypsin; (iii) 12 Mab, including F2B2 and F12A3, that react with the receptor-binding domain, neo-antigenically expressed on alpha 2M-trypsin, (iv)O six Mab that are also specific for alpha 2M-trypsin but map outside the receptor-binding domain; (v) three Mab that define hidden determinants, not expressed on undenatured alpha 2M. For completeness, the panel includes the Mab obtained against pregnancy zone protein.

  11. The g2 Structure Function

    SciTech Connect

    Matthias Burkardt

    2009-07-01

    Polarized structure functions at low $Q^2$ have the physical interpretation of (generalized) spin polarizabilities. At high $Q^2$, the polarized parton distribution $g_2(x)$ provides access to quark-gluon correlations in the nucleon. We discuss the interpretation of the $x^2$ moment of $\\bar{g}_2(x)$ as an average transverse force on quarks in deep-inelastic scattering from a transversely polarized target. Qualitative connections with generalized parton distributions are emphasized. The $x^2$ moment of the chirally-odd twist-3 parton distribution $e(x)$ provides information on the dependence of the average transverse force on the transversity of the quark.

  12. Longitudinal Structure Function F L of Proton from Regge Like Behaviour of Structure Function at Small-x

    NASA Astrophysics Data System (ADS)

    Baruah, Nomita; Das, Mrinal Kumar; Sarma, Jayanta Kumar

    2014-08-01

    The evolutions of longitudinal structure function F L from quantum chromodynamics (QCD) evolution equation in next-to-leading order at small-x is presented using the Regge like behaviour of the structure function. The proposed simple analytical expression for F L structure function provides the t- and x-evolution equations to study the behaviour of F L structure function at small-x. The calculated results are compared with the data of H1, ZEUS collaborations and results of Block model, Donnachie-Landshoff model. Our calculated results can be described within the framework of perturbative QCD.

  13. Structure Functions at Low Q^2: Target Mass Corrections

    SciTech Connect

    Wally Melnitchouk

    2007-05-30

    We discuss recent developments in the study of structure functions at low Q^2, focusing in particular on the issue of target mass corrections (TMC) to nucleon structure functions. We summarize the standard TMC implementation, and contrast this with a new formulation which has the correct kinematic threshold behavior at finite Q^2 in the x -> 1 limit.

  14. Calcite dissolution: an in situ study in the Panama Basin

    SciTech Connect

    Thunell, R.C.; Keir, R.S.; Honjo, S.

    1981-05-08

    The results of an in situ study of calcite dissolution in the Panama Basin indicate that the rate of dissolution in the water column increases suddenly below a water depth of about 2800 meters. This coincides with the depth at which the calcium carbonate content of surface sediments begins to decrease rapidly or the sedimentary lysocline. Since this level of increased dissolution both in the water column and on the sea floor does not appear to be related to the transition from supersaturation to undersaturation with respect to carbonate, there may be a kinetic origin for the lysocline in this region.

  15. In situ STM studies of polycrystalline platinum electrodes

    NASA Astrophysics Data System (ADS)

    Szklarczyk, Marek; Bockris, John O'M.

    1991-01-01

    In situ scanning tunneling microscopy (STM) was applied in a 10 -2M NaClO 4 solution to study topographical changes of a platinum electrode surface due to its oxidation and reduction. Surface morphology depends on the electrode potential. There are two stages in surface reduction: the fast electrochemical charge transfer and the slow crystallographic reconstruction. Reconstruction during surface reduction tends to proceed in the direction of the topography obtained during the annealing process. Methods of avoiding Faradaic current flowing through the STM tip are discussed in detail.

  16. Calcite Dissolution: An in situ Study in the Panama Basin.

    PubMed

    Thunell, R C; Keir, R S; Honjo, S

    1981-05-08

    The results of an in situ study of calcite dissolution in the Panama Basin indicate that the rate of dissolution in the water column increases suddenly below a water depth of about 2800 meters. This coincides with the depth at which the calcium carbonate content of surface sediments begins to decrease rapidly or the sedimentary lysocline. Since this level of increased dissolution both in the water column and on the sea floor does not appear to be related to the transition from supersaturation to undersaturation with respect to carbonate, there may be a kinetic origin for the lysocline in this region.

  17. In situ TEM studies of carbon and gold nanostructures

    NASA Astrophysics Data System (ADS)

    Casillas Garcia, Gilberto

    Properties of matter change as structures go down in size to the nanoscale, creating new possibilities for creating new functional materials with better properties than the bulk. In situ TEM techniques were used to probe the properties of two different materials: atomic carbon chains and gold nanoparticles. Carbon chains were synthesized by in situ TEM electron beam irradiation from few-layers-graphene (FLG) flakes. Several chains up to 5 nm long were observed. Aberration corrected TEM confirmed the dimerization of the linear chain as predicted by Peierls. Moreover, it was observed that two linear carbon chains can cross-bond every 9 atoms, and it was confirmed by DFT calculations. Five-fold nanoparticles are not supposed to be stable beyond 5 nm size. Here, decahedra with high index facets in the order of 300 nm were studied by TEM. It was found that the high index facets were only stable by adding a capping agent, otherwise, smooth edges were observed. In this case, a (5x1) hexagonal surface reconstruction was observed on the {001} surfaces, with the hexagonal strings along a [110] and a [410] direction. Additionally, mechanical properties of gold nanoparticles, with and without twin boundaries, under 100 nm were measured by in situ TEM compression experiments. All of the nanoparticles presented yield strengths in the order of GPa. Multi twinned nanoparticles were found to be more malleable, reaching real compressing strains of 100 %, while the single crystal nanoparticle presented less plastic flow. Molecular dynamics simulations revealed that the twin boundaries contribute to the malleability of the nanoparticles, at the same time it provides a mechanism to stop dislocations, hence, strain hardening the nanoparticle at later stages of compression. Finally, the behavior of a single grain boundary was studied by in situ TEM manipulation of nanoparticles. A liquid-like behavior of a grain boundary is observed after two 40 nm gold nanoparticles are brought to

  18. In situ studies and modeling the fracture of Zircaloy-4

    NASA Astrophysics Data System (ADS)

    Cockeram, B. V.; Chan, K. S.

    2009-09-01

    In situ fracture studies were performed on non-irradiated Zircaloy-4 using tensile specimens and pre-cracked Compact Tension (CT) specimens to clarify the mechanism for fracture initiation in the constrained and non-constrained state. Similar approaches have been taken in the literature to understand the role of hydrides on the fracture of Zircaloy-4, but hydride-free Zircaloy-4 has received little study. Both annealed and beta-treated Zircaloy-4 were tested in the longitudinal, transverse, and short-transverse orientations to study the role of microstructure and orientation. Unstable crack extension is shown to occur under plastic constraint by a process of void nucleation, growth, and coalescence initiating from the Laves phase particles in the microstructure. A micromechanical model is developed for ductile tearing by void growth and coalescence. Excellent agreement between the model and experiments are observed. Aspects of the fracture mechanism and model are discussed.

  19. Structure-function relationship of gonadotropins

    SciTech Connect

    Bellet, D.; Bidart, J.M.

    1989-01-01

    In this book, investigators highlight progress recently made in research on the structure-function relationship of gonadotropins. The contributors provide coverage of major breakthroughs such as the cloning of the ovarian receptor for lutropin and choriogonadotropin, the elucidation of the structure of this receptor, and the first crystallographic studies of human chorionic gonadotropin. The book also describes significant advances in the epitope mapping of gonadotropins, the immunochemical and biochemical study of their structure, the examination of regulatory processes involved in subunit association, and the elucidation of the complex mechanisms responsible for regulation and expression of gonadotropin genes.

  20. In situ ellipsometric study of surface immobilization of flagellar filaments

    NASA Astrophysics Data System (ADS)

    Kurunczi, S.; Németh, A.; Hülber, T.; Kozma, P.; Petrik, P.; Jankovics, H.; Sebestyén, A.; Vonderviszt, F.; Fried, M.; Bársony, I.

    2010-10-01

    Protein filaments composed of thousands of subunits are promising candidates as sensing elements in biosensors. In this work in situ spectroscopic ellipsometry is applied to monitor the surface immobilization of flagellar filaments. This study is the first step towards the development of layers of filamentous receptors for sensor applications. Surface activation is performed using silanization and a subsequent glutaraldehyde crosslinking. Structure of the flagellar filament layers immobilized on activated and non-activated Si wafer substrates is determined using a two-layer effective medium model that accounted for the vertical density distribution of flagellar filaments with lengths of 300-1500 nm bound to the surface. The formation of the first interface layer can be explained by the multipoint covalent attachment of the filaments, while the second layer is mainly composed of tail pinned filaments floating upwards with the free parts. As confirmed by atomic force microscopy, covalent immobilization resulted in an increased surface density compared to absorption.

  1. Integral structural-functional method for characterizing microbial populations

    NASA Astrophysics Data System (ADS)

    Yakushev, A. V.

    2015-04-01

    An original integral structural-functional method has been proposed for characterizing microbial communities. The novelty of the approach is the in situ study of microorganisms based on the growth kinetics of microbial associations in liquid nutrient broth media under selective conditions rather than on the level of taxa or large functional groups. The method involves the analysis of the integral growth model of a periodic culture. The kinetic parameters of such associations reflect their capacity of growing on different media, i.e., their physiological diversity, and the metabolic capacity of the microorganisms for growth on a nutrient medium. Therefore, the obtained parameters are determined by the features of the microbial ecological strategies. The inoculation of a dense medium from the original inoculate allows characterizing the taxonomic composition of the dominants in the soil community. The inoculation from the associations developed on selective media characterizes the composition of syntrophic groups, which fulfill a specific function in nature. This method is of greater information value than the classical methods of inoculation on selective media.

  2. Mechanistic studies of malonic acid-mediated in situ acylation.

    PubMed

    Chandra, Koushik; Naoum, Johnny N; Roy, Tapta Kanchan; Gilon, Chaim; Gerber, R Benny; Friedler, Assaf

    2015-09-01

    We have previously introduced an easy to perform, cost-effective and highly efficient acetylation technique for solid phase synthesis (SPPS). Malonic acid is used as a precursor and the reaction proceeds via a reactive ketene that acetylates the target amine. Here we present a detailed mechanistic study of the malonic acid-mediated acylation. The influence of reaction conditions, peptide sequence and reagents was systematically studied. Our results show that the methodology can be successfully applied to different types of peptides and nonpeptidic molecules irrespective of their structure, sequence, or conformation. Using alkyl, phenyl, and benzyl malonic acid, we synthesized various acyl peptides with almost quantitative yields. The ketenes obtained from the different malonic acid derived precursors were characterized by in situ (1) H-NMR. The reaction proceeded in short reaction times and resulted in excellent yields when using uronium-based coupling agents, DIPEA as a base, DMF/DMSO/NMP as solvents, Rink amide/Wang/Merrifield resins, temperature of 20°C, pH 8-12 and 5 min preactivation at inert atmosphere. The reaction was unaffected by Lewis acids, transition metal ions, surfactants, or salt. DFT studies support the kinetically favorable concerted mechanism for CO2 and ketene formation that leads to the thermodynamically stable acylated products. We conclude that the malonic acid-mediated acylation is a general method applicable to various target molecules.

  3. Sample environment for in situ synchrotron corrosion studies of materials in extreme environments

    DOE PAGES

    Elbakhshwan, Mohamed S.; Gill, Simerjeet K.; Motta, Arthur T.; ...

    2016-10-25

    A new in situ sample environment has been designed and developed to study the interfacial interactions of nuclear cladding alloys with high temperature steam. The sample environment is particularly optimized for synchrotron X-ray diffraction (XRD) studies for in situ structural analysis. The sample environment is highly corrosion resistant and can be readily adapted for steam environments. The in situ sample environment design complies with G2 ASTM standards for studying corrosion in zirconium and its alloys and offers remote temperature and pressure monitoring during the in situ data collection. The use of the in situ sample environment is exemplified by monitoringmore » the oxidation of metallic zirconium during exposure to steam at 350°C. Finally, the in situ sample environment provides a powerful tool for fundamental understanding of corrosion mechanisms by elucidating the substoichiometric oxide phases formed during early stages of corrosion, which can provide a better understanding the oxidation process.« less

  4. Microbial Studies Supporting Implementation of In Situ Bioremediation at TAN

    SciTech Connect

    Barnes, Joan Marie; Matthern, Gretchen Elise; Rae, Catherine; Ely, R. L.

    2000-11-01

    The Idaho National Engineering and Environmental Laboratory is evaluating in situ bioremediation of contaminated groundwater at its Test Area North Facility. To determine feasibility, microcosm and bioreactor studies were conducted to ascertain the ability of indigenous microbes to convert trichloroethene and dichloroethene to non-hazardous byproducts under aerobic and anaerobic conditions, and to measure the kinetics of microbial reactions associated with the degradation process. Microcosms were established from core samples and groundwater obtained from within the contaminant plume. These microcosms were amended with nutrients, under aerobic and anaerobic conditions, to identify electron donors capable of stimulating the degradation process. Results of the anaerobic microcosm studies showed that lactate, acetate and propionate amendments stimulated indigenous cell growth and functioned as effective substrates for reductive degradation of chloroethenes. Bioreactors inoculated with cultures from these anaerobic microcosms were operated under a batch mode for 42 days then converted to a fed-batch mode and operated at a 53-day hydraulic residence time. It was demonstrated that indigenous microbes capable of complete anaerobic reductive dechlorination are present in the subject well. It was also demonstrated that aerobic microbes capable of oxidizing chlorinated compounds produced by anaerobic reductive dechlorination are present. Kinetic data suggest that controlling the type and concentration of electron donors can increase trichlorethene conversion rates. In the event that complete mineralization of trichlorethene does not occur following stimulation, and anaerobic/aerobic treatment scheme is feasible.

  5. Guanylyl cyclase structure, function and regulation.

    PubMed

    Potter, Lincoln R

    2011-12-01

    Nitric oxide, bicarbonate, natriuretic peptides (ANP, BNP and CNP), guanylins, uroguanylins and guanylyl cyclase activating proteins (GCAPs) activate a family of enzymes variously called guanyl, guanylyl or guanylate cyclases that catalyze the conversion of guanosine triphosphate to cyclic guanosine monophosphate (cGMP) and pyrophosphate. Intracellular cyclic GMP is a second messenger that modulates: platelet aggregation, neurotransmission, sexual arousal, gut peristalsis, blood pressure, long bone growth, intestinal fluid secretion, lipolysis, phototransduction, cardiac hypertrophy and oocyte maturation. This review briefly discusses the discovery of cGMP and guanylyl cyclases, then nitric oxide, nitric oxide synthase and soluble guanylyl cyclase are described in slightly greater detail. Finally, the structure, function, and regulation of the individual mammalian single membrane-spanning guanylyl cyclases GC-A, GC-B, GC-C, GC-D, GC-E, GC-F and GC-G are described in greatest detail as determined by biochemical, cell biological and gene-deletion studies.

  6. The Saturn Ring Observer: In situ studies of planetary rings

    NASA Astrophysics Data System (ADS)

    Nicholson, P. D.; Tiscareno, M. S.; Spilker, L. J.

    2010-12-01

    As part of the Planetary Science Decadal Survey recently undertaken by the NRC's Space Studies Board for the National Academy of Sciences, studies were commissioned for a number of potential missions to outer planet targets. One of these studies examined the technological feasibility of a mission to carry out in situ studies of Saturn's rings, from a spacecraft placed in a circular orbit above the ring plane: the Saturn Ring Observer. The technical findings and background are discussed in a companion poster by T. R. Spilker et al. Here we outline the science goals of such a mission. Most of the fundamental interactions in planetary rings occur on spatial scales that are unresolved by flyby or orbiter spacecraft. Typical particle sizes in the rings of Saturn are in the 1 cm - 10 m range, and average interparticle spacings are a few meters. Indirect evidence indicates that the vertical thickness of the rings is as little as 5 - 10 m, which implies a velocity dispersion of only a few mm/sec. Theories of ring structure and evolution depend on the unknown characteristics of interparticle collisions and on the size distribution of the ring particles. The SRO could provide direct measurements of both the coefficient of restitution -- by monitoring individual collisions -- and the particles’ velocity dispersion. High-resolution observations of individual ring particles should also permit estimates of their spin states. Numerical simulations of Saturn’s rings incorporating both collisions and self-gravity predict that the ring particles are not uniformly distributed, but are instead clustered into elongated structures referred to as “self-gravity wakes”, which are continually created and destroyed on an orbital timescale. Theory indicates that the average separation between wakes in the A ring is of order 30-100 m. Direct imaging of self-gravity wakes, including their formation and subsequent dissolution, would provide critical validation of these models. Other

  7. Mass Effects on the Nucleon Sea Structure Functions

    NASA Astrophysics Data System (ADS)

    Kim, Sun Myong

    Nucleon sea structure functions are studied using Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations with the massive gluon-quark splitting kernels for strange and charm quarks, the massless gluon-quark splitting kernels for up and down quarks, and the massless kernels for all other splitting parts. The SU(2)f flavor symmetry for two light quarks, ``up'' and ``down'', is assumed. Glück-Reya-Vogt (GRV) and Martin-Roberts-Stirling (MRS) sets are chosen to be the base structure functions at Q02=3 GeV2. We evolve the sea structure functions from Q02=3 GeV2 to Q2=50 GeV2 using the base structure function sets and DGLAP equations. Some (about 10%) enhancement is found in the strange quark distribution functions at low x (<0.1) in leading order of the DGLAP equations compared to results directly from those structure function sets at the value of Q2=50 GeV2. We provide the value of κ and also show the behavior of κ (x)=2s(x)/(¯ u(x)+¯ d(x)) after the evolution of structure functions.

  8. In Situ Coral Reef Oxygen Metabolism: An Eddy Correlation Study

    PubMed Central

    Long, Matthew H.; Berg, Peter; de Beer, Dirk; Zieman, Joseph C.

    2013-01-01

    Quantitative studies of coral reefs are challenged by the three-dimensional hard structure of reefs and the high spatial variability and temporal dynamics of their metabolism. We used the non-invasive eddy correlation technique to examine respiration and photosynthesis rates, through O2 fluxes, from reef crests and reef slopes in the Florida Keys, USA. We assessed how the photosynthesis and respiration of different reef habitats is controlled by light and hydrodynamics. Numerous fluxes (over a 0.25 h period) were as high as 4500 mmol O2 m−2 d−1, which can only be explained by efficient light utilization by the phototrophic community and the complex canopy structure of the reef, having a many-fold larger surface area than its horizontal projection. Over diel cycles, the reef crest was net autotrophic, whereas on the reef slope oxygen production and respiration were balanced. The autotrophic nature of the shallow reef crests implies that the export of organics is an important source of primary production for the larger area. Net oxygen production on the reef crest was proportional to the light intensity, up to 1750 µmol photons m−2 s−1 and decreased thereafter as respiration was stimulated by high current velocities coincident with peak light levels. Nighttime respiration rates were also stimulated by the current velocity, through enhanced ventilation of the porous framework of the reef. Respiration rates were the highest directly after sunset, and then decreased during the night suggesting that highly labile photosynthates produced during the day fueled early-night respiration. The reef framework was also important to the acquisition of nutrients as the ambient nitrogen stock in the water had sufficient capacity to support these high production rates across the entire reef width. These direct measurements of complex reefs systems yielded high metabolic rates and dynamics that can only be determined through in situ, high temporal resolution measurements

  9. Degradation of Bimetallic Model Electrocatalysts ___ an in situ XAS Study

    SciTech Connect

    Friebel, Daniel

    2011-06-22

    One of the major challenges in the development of clean energy fuel cells is the performance degradation of the electrocatalyst, which, apart from poisoning effects, can suffer from corrosion due to its exposure to a harsh environment under high potentials. In this communication, we demonstrate how interactions of Pt with a transition metal support affect not only, as commonly intended, the catalytic activity, but also the reactivity of Pt towards oxide formation or dissolution. We use two well-defined single-crystal model systems, Pt/Rh(111) and Pt/Au(111) and a unique x-ray spectroscopy technique with enhanced energy resolution to monitor the potential-dependent oxidation state of Pt, and find two markedly different oxidation mechanisms on the two different substrates. This information can be of great significance for future design of more active and more stable catalysts. We have studied the potential-induced degradation of Pt monolayer model electrocatalysts on Rh(111) and Au(111) single-crystal substrates. The anodic formation of Pt oxides was monitored using in situ high energy resolution fluorescence detection x-ray absorption spectroscopy (HERFD XAS). Although Pt was deposited on both substrates in a three-dimensional island growth mode, we observed remarkable differences during oxide formation that can only be understood in terms of strong Pt-substrate interactions throughout the Pt islands. Anodic polarization of Pt/Rh(111) up to +1.6 V vs. RHE (reversible hydrogen electrode) leads to formation an incompletely oxidized passive layer, whereas formation of PtO2 and partial Pt dissolution is observed for Pt/Au(111).

  10. Oral microemulsions of paclitaxel: in situ and pharmacokinetic studies.

    PubMed

    Nornoo, Adwoa O; Zheng, Haian; Lopes, Luciana B; Johnson-Restrepo, Boris; Kannan, Kurunthachalam; Reed, Rachel

    2009-02-01

    The overall goal of this study was to develop cremophor-free oral microemulsions of paclitaxel (PAC) to enhance its permeability and oral absorption. The mechanism of this enhancement, as well as characteristics of the microemulsions relevant to the increase in permeability and absorption of the low solubility, low permeability PAC was investigated. Phase diagrams were used to determine the macroscopic phase behavior of the microemulsions and to compare the efficiency of different surfactant-oil mixtures to incorporate water. The microemulsion region on the phase diagrams utilizing surfactant-myvacet oil combinations was in decreasing order: lecithin: butanol: myvacet oil (LBM, 48.5%)>centromix CPS: 1-butanol: myvacet oil (CPS, 45.15%)>capmul MCM: polysorbate 80: myvacet oil (CPM, 27.6%)>capryol 90: polysorbate 80: myvacet oil (CP-P80, 23.9%)>capmul: myvacet oil (CM, 20%). Oil-in-water (o/w) microemulsions had larger droplet sizes (687-1010 nm) than the water-in-oil (w/o) microemulsions (272-363 nm) when measured using a Zetasizer nano series particle size analyzer. Utilizing nuclear magnetic resonance spectroscopy (NMR), the self-diffusion coefficient (D) of PAC in CM, LBM and CPM containing 10% of deuterium oxide (D(2)O) was 2.24x10(-11), 1.97x10(-11) and 0.51x10(-11) m(2)/s, respectively. These values indicate the faster molecular mobility of PAC in the two w/o microemulsions (CM and LBM) than the o/w microemulsion--CPM. The in situ permeability of PAC through male CD-IGS rat intestine was 3- and 11-fold higher from LBM and CM, respectively, than that from the control clinical formulation, Taxol (CE, cremophor: ethanol) in a single pass perfusion study. PAC permeability was significantly increased in the presence of the pgp/CYP3A4 inhibitor cyclosporine A (CsA). This enhancement may be attributed to the pgp inhibitory effect of the surfactants, oil and/or the membrane perturbation effect of the surfactants. The oral disposition of PAC in CM, LBM and CPM compared

  11. Process-Structure-Function Relations of Pectin in Food.

    PubMed

    Christiaens, Stefanie; Van Buggenhout, Sandy; Houben, Ken; Jamsazzadeh Kermani, Zahra; Moelants, Katlijn R N; Ngouémazong, Eugénie D; Van Loey, Ann; Hendrickx, Marc E G

    2016-01-01

    Pectin, a complex polysaccharide rich in galacturonic acid, has been identified as a critical structural component of plant cell walls. The functionality of this intricate macromolecule in fruit- and vegetable-based-derived products and ingredients is strongly determined by the nanostructure of its most abundant polymer, homogalacturonan. During food processing, pectic homogalacturonan is susceptible to various enzymatic as well as nonenzymatic conversion reactions modifying its structural and, hence, its functional properties. Consequently, a profound understanding of the various process-structure-function relations of pectin aids food scientists to tailor the functional properties of plant-based derived products and ingredients. This review describes the current knowledge on process-structure-function relations of pectin in foods with special focus on pectin's functionality with regard to textural attributes of solid plant-based foods and rheological properties of particulated fruit- and vegetable-derived products. In this context, both pectin research performed via traditional, ex situ physicochemical analyses of fractionated walls and isolated polymers and pectin investigation through in situ pectin localization are considered.

  12. Synthesis of nitrate sodalite: An in situ scanning calorimetric study

    NASA Astrophysics Data System (ADS)

    Liu, Qingyuan; Navrotsky, Alexandra

    2007-04-01

    The formation of nitrate sodalite, an important constituent of the resilient heels at DOE nuclear waste storage sites, was closely followed by oven synthesis, in situ calorimetry as a function of heating rate from 0.01 to 0.1 °C/min and X-ray diffraction. A transition sequence of amorphous-zeolite A-sodalite-cancrinite was confirmed. For in situ synthesis calorimetry, the heat flow peaks related to zeolite A formation are shifted to higher temperatures as heating rate increases. Although the end products are mostly nitrate sodalite, no calorimetric signals associated with zeolite A to sodalite conversion are detected. This suggests that the enthalpy of formation of zeolite A and sodalite are very similar and the zeolite A to sodalite conversion enthalpy is small. This conclusion is in accord with previous measurements by oxide melt solution calorimetry.

  13. In Situ Optical Studies of Solid-Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Pomfret, Michael B.; Owrutsky, Jeffrey C.; Walker, Robert A.

    2010-07-01

    Thermal imaging and vibrational spectroscopy have become important tools for examining the physical and chemical changes that occur in real time in solid-oxide fuel cells (SOFCs). Imaging techniques can resolve temperature differences as fine as 0.1°C across a SOFC electrode at temperatures higher than 600°C. Vibrational spectroscopy can identify molecular species and changes in material phases in operating SOFCs. This review discusses the benefits and challenges associated with directly observing processes that are important to SOFC performance and durability. In situ optical methods can provide direct insight into reaction mechanisms that can be inferred only indirectly from electrochemical measurements such as voltammetry and electrochemical impedance spectroscopy and from kinetic models and postmortem, ex situ examinations of SOFC components. Particular attention is devoted to recent advances that, hopefully, will spur the development of new generations of efficient, versatile energy-producing devices.

  14. In situ optical studies of solid-oxide fuel cells.

    PubMed

    Pomfret, Michael B; Owrutsky, Jeffrey C; Walker, Robert A

    2010-01-01

    Thermal imaging and vibrational spectroscopy have become important tools for examining the physical and chemical changes that occur in real time in solid-oxide fuel cells (SOFCs). Imaging techniques can resolve temperature differences as fine as 0.1 degrees C across a SOFC electrode at temperatures higher than 600 degrees C. Vibrational spectroscopy can identify molecular species and changes in material phases in operating SOFCs. This review discusses the benefits and challenges associated with directly observing processes that are important to SOFC performance and durability. In situ optical methods can provide direct insight into reaction mechanisms that can be inferred only indirectly from electrochemical measurements such as voltammetry and electrochemical impedance spectroscopy and from kinetic models and postmortem, ex situ examinations of SOFC components. Particular attention is devoted to recent advances that, hopefully, will spur the development of new generations of efficient, versatile energy-producing devices.

  15. Evolving Technologies for In-Situ Studies of Mars Ice

    NASA Technical Reports Server (NTRS)

    Carsey, F. D.; Hecht, M. H.

    2003-01-01

    Icy sites on Mars continue to be of high scientific importance. These sites include the polar caps, the southern mid-latitude subsurface permafrost, and the seasonal frost. These sites have interest due to their roles in climate processes, past climates, surface and near-surface water, astrobiology, geomorphology, and other topics. As is the case for many planetary features, remote sensing, while of great value, cannot answer all questions; in-situ examination is essential, and the motivation for in-situ observations generally leads to the subsurface, which, fortunately, is accessible on Mars. It is clear in fact that a Mars polar cap subsurface mission is both scientifically compelling and practical. Recent data from orbiting platforms has provided a remarkable level of information about the Mars ice caps; we know, for example, the size, shape and annual cycle of the cap topography as well as we know that of Earth, and we have more information on stratification that we have of, for example, the ice of East Antarctica. To understand the roles that the Mars polar caps play, it is necessary to gather information on the ice cap surface, strata, composition and bed. In this talk the status of in-situ operations and observations will be summarized, and, since we have conveniently at hand another planet with polar caps, permafrost and ice, the role of testing and validation of experimental procedures on Earth will be addressed.

  16. Holographic microscopy for in situ studies of microorganism motility

    NASA Astrophysics Data System (ADS)

    Nadeau, J.; Hu, S.; Jericho, S.; Lindensmith, C.

    2011-12-01

    Robust technologies for the detection and identification of microorganisms at low concentrations in complex liquid media are needed for numerous applications: environmental and medical microbiology, food safety, and for the search for microbial life elsewhere in the Solar System. The best current method for microbial enumeration is specific labeling with fluorescent dyes followed by high-resolution light microscopy. However, fluorescent techniques are difficult to use in situ in extreme environments (such as the Arctic and Antarctic or the open ocean) due to the fragility of the instruments and their high power demands. In addition, light microscopic techniques rarely provide insight into microbial motility behaviors. Tracking single cells would provide important insight into the physics of micron-scale motility as well as into key microbial phenomena such as surface attachment and invasiveness. An alternative to traditional light microscopy that is attracting increasing attention is holographic microscopy. Holographic microscopy works by illuminating the object of interest with coherent light from a laser. The light reflected from (or transmitted through) the object is then combined with a coherent reference beam to create an interference pattern that contains the phase and intensity information required to reconstruct a three dimensional image of the object. The interference pattern is recorded on a high resolution detector and can be used to computationally reconstruct a 3D image of the object. The lateral resolution of the image depends upon the wavelength of the light used, the laser power, camera quality, and external noise sources (vibration, stray light, and so forth). Although the principle is simple, technological barriers have prevented wider use of holographic microscopy. Laser sources and CCD cameras with the appropriate properties have only very recently become affordable. In addition, holographic microscopy leads to large data sets that are

  17. Next-order structure-function equations

    NASA Astrophysics Data System (ADS)

    Hill, Reginald J.; Boratav, Olus N.

    2001-01-01

    Kolmogorov's equation [Dokl. Akad. Nauk SSSR 32, 16 (1941)] relates the two-point second- and third-order velocity structure functions and the energy dissipation rate. The analogous next higher-order two-point equation relates the third- and fourth-order velocity structure functions and the structure function of the product of pressure-gradient difference and two factors of velocity difference, denoted Tijk. The equation is simplified on the basis of local isotropy. Laboratory and numerical simulation data are used to evaluate and compare terms in the equation, examine the balance of the equation, and evaluate components of Tijk. Atmospheric surface-layer data are used to evaluate Tijk in the inertial range. Combined with the random sweeping hypothesis, the equation relates components of the fourth-order velocity structure function. Data show the resultant error of this application of random sweeping. The next-order equation constrains the relationships that have been suggested among components of the fourth-order velocity structure function. The pressure structure function, pressure-gradient correlation, and mean-squared pressure gradient are related to Tijk. Inertial range formulas are discussed.

  18. Combining Exergame Training with Omega-3 Fatty Acid Supplementation: Protocol for a Randomized Controlled Study Assessing the Effect on Neuronal Structure/Function in the Elderly Brain

    PubMed Central

    Schättin, Alexandra; de Bruin, Eling D.

    2016-01-01

    A common problem in the older population is the risk of falling and related injury, immobility, and reduced survival. Age-related neuronal changes, e.g., decline in gray-and white-matter, affect neuronal, cognitive, and motor functioning. The improvement of these factors might decrease fall events in elderly. Studies showed that administration of video game-based physical exercise, a so-called exergame, or omega-3 fatty acid (FA) may improve motor and/or cognitive functioning through neuronal changes in the brain of older adults. The aim of this study is to assess the effects of a combination of exergame training with omega-3 FA supplementation on the elderly brain. We hypothesize that an intervention using a combination approach differently affects on the neuronal structure and function of the elderly's brain as compared to the sole administration of exergame training. The study is a parallel, double-blinded, randomized controlled trial lasting 26 weeks. Sixty autonomous living, non-smoking, and right-handed healthy older (>65 years) adults who live independently or in a senior residency are included, randomized, and allocated to one of two study groups. The experimental group receives a daily amount of 13.5 ml fish oil (including 2.9 g of omega-3 FA), whereas the control group receives a daily amount of 13.5 ml olive oil for 26 weeks. After 16 weeks, both groups start with an exergame training program three times per week. Measurements are performed on three time-points by treatment blinded investigators: pre-intervention measurements, blood sample after 16 week, and post-intervention measurements. The main outcomes are motor evoked potentials of the right M. tibialis anterior (transcranial magnetic stimulation) and response-related potentials (electroencephalography) during a cognitive test. For secondary outcomes, reaction time during cognitive tests and spatio-temporal parameters during gait performance are measured. Statistics will include effect sizes and a

  19. Combining Exergame Training with Omega-3 Fatty Acid Supplementation: Protocol for a Randomized Controlled Study Assessing the Effect on Neuronal Structure/Function in the Elderly Brain.

    PubMed

    Schättin, Alexandra; de Bruin, Eling D

    2016-01-01

    A common problem in the older population is the risk of falling and related injury, immobility, and reduced survival. Age-related neuronal changes, e.g., decline in gray-and white-matter, affect neuronal, cognitive, and motor functioning. The improvement of these factors might decrease fall events in elderly. Studies showed that administration of video game-based physical exercise, a so-called exergame, or omega-3 fatty acid (FA) may improve motor and/or cognitive functioning through neuronal changes in the brain of older adults. The aim of this study is to assess the effects of a combination of exergame training with omega-3 FA supplementation on the elderly brain. We hypothesize that an intervention using a combination approach differently affects on the neuronal structure and function of the elderly's brain as compared to the sole administration of exergame training. The study is a parallel, double-blinded, randomized controlled trial lasting 26 weeks. Sixty autonomous living, non-smoking, and right-handed healthy older (>65 years) adults who live independently or in a senior residency are included, randomized, and allocated to one of two study groups. The experimental group receives a daily amount of 13.5 ml fish oil (including 2.9 g of omega-3 FA), whereas the control group receives a daily amount of 13.5 ml olive oil for 26 weeks. After 16 weeks, both groups start with an exergame training program three times per week. Measurements are performed on three time-points by treatment blinded investigators: pre-intervention measurements, blood sample after 16 week, and post-intervention measurements. The main outcomes are motor evoked potentials of the right M. tibialis anterior (transcranial magnetic stimulation) and response-related potentials (electroencephalography) during a cognitive test. For secondary outcomes, reaction time during cognitive tests and spatio-temporal parameters during gait performance are measured. Statistics will include effect sizes and a

  20. Dehydrogenation and Sintering of TiH2: An In Situ Study

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Liss, Klaus D.; Auchterlonie, Graeme; Tang, Huiping; Cao, Peng

    2017-03-01

    This first-ever study investigated dehydrogenation and microstructural evolution of TiH2 during sintering under vacuum using in situ neutron diffraction, in situ transmission electron microscopy, and ex situ neutron tomography. The densification behavior, microstructure, hydrogen concentration, and in situ phase transformation were reported. The shrinkage, weight loss percentage, and densification of the TiH2 powder compact monotonically increase with sintering temperature, while the open porosity behaves differently; porosity first increases at the initial sintering stage and then decreases during further sintering. The in situ phase transformation observations reveal that dehydrogenation starts from the outer area of either a particle or a powder compact and progressively carries forward into the interior of the particle or the compact. A shrinking core model was proposed to elucidate the dehydrogenation process for a single particle and a powder compact.

  1. Generation of recombinant monoclonal antibodies to study structure-function of envelope protein VP28 of white spot syndrome virus from shrimp

    SciTech Connect

    Wang Yuzhen; Zhang Xiaohua; Yuan Li; Xu Tao; Rao Yu; Li Jia; Dai Heping

    2008-08-08

    White spot syndrome virus (WSSV) is a major pathogen in shrimp aquaculture. VP28 is one of the most important envelope proteins of WSSV. In this study, a recombinant antibody library, as single-chain fragment variable (scFv) format, displayed on phage was constructed using mRNA from spleen cells of mice immunized with full-length VP28 expressed in Escherichia coli. After several rounds of panning, six scFv antibodies specifically binding to the epitopes in the N-terminal, middle, and C-terminal regions of VP28, respectively, were isolated from the library. Using these scFv antibodies as tools, the epitopes in VP28 were located on the envelope of the virion by immuno-electron microscopy. Neutralization assay with these antibodies in vitro suggested that these epitopes may not be the attachment site of WSSV to host cell receptor. This study provides a new way to investigate the structure and function of the envelope proteins of WSSV.

  2. Structure-function relationships in the context of reinforcement-related learning: a combined diffusion tensor imaging-functional magnetic resonance imaging study.

    PubMed

    Koch, K; Wagner, G; Dahnke, R; Schachtzabel, C; Güllmar, D; Reichenbach, J R; Schlösser, R G M

    2010-06-16

    In the context of probabilistic learning, previous functional magnetic resonance imaging studies have shown decreasing uncertainty accompanying decreasing neuronal activation in task-relevant networks. Moreover, initial evidence points to a relationship between white matter structure and cognitive performance. Little is known, however, about the structural correlates underlying individual differences in activation and performance in the context of probabilistic learning. This combined functional magnetic resonance imaging-diffusion tensor imaging study aimed at investigating the individual ability to reduce processing resources with decreasing uncertainty in direct relation to individual characteristics in white matter brain structure. Results showed that more successful learners, as compared with less successful learners, exhibited stronger activation decreases with decreasing uncertainty. An increased mean and axial diffusivity in, among others, the inferior and superior longitudinal fasciculus, the posterior part of the cingulum bundle, and the corpus callosum were detectable in less successful learners compared with more successful learners. Most importantly, there was a negative correlation between uncertainty-related activation and diffusivity in a fronto-parieto-striatal network in less successful learners only, indicating a direct relation between diffusivity and the ability to reduce processing resources with decreasing uncertainty. These findings indicate that interindividual variations in white matter characteristics within the normal population might be linked to neuronal activation and critically influence individual learning performance.

  3. In vivo structure-function studies of human hepatic lipase: the catalytic function rescues the lean phenotype of HL-deficient (hl-/-) mice.

    PubMed

    Chen, Jeffrey; Kaiyala, Karl J; Lam, Jennifer; Agrawal, Nalini; Nguyen, Lisa; Ogimoto, Kayoko; Spencer, Dean; Morton, Gregory J; Schwartz, Michael W; Dichek, Helén L

    2015-04-01

    The lean body weight phenotype of hepatic lipase (HL)-deficient mice (hl(-/-)) suggests that HL is required for normal weight gain, but the underlying mechanisms are unknown. HL plays a unique role in lipoprotein metabolism performing bridging as well as catalytic functions, either of which could participate in energy homeostasis. To determine if both the catalytic and bridging functions or the catalytic function alone are required for the effect of HL on body weight, we studied (hl(-/-)) mice that transgenically express physiologic levels of human (h)HL (with catalytic and bridging functions) or a catalytically-inactive (ci)HL variant (with bridging function only) in which the catalytic Serine 145 was mutated to Alanine. As expected, HL activity in postheparin plasma was restored to physiologic levels only in hHL-transgenic mice (hl(-/-)hHL). During high-fat diet feeding, hHL-transgenic mice exhibited increased body weight gain and body adiposity relative to hl(-/-)ciHL mice. A similar, albeit less robust effect was observed in female hHL-transgenic relative to hl(-/-)ciHL mice. To delineate the basis for this effect, we determined cumulative food intake and measured energy expenditure using calorimetry. Interestingly, in both genders, food intake was 5-10% higher in hl(-/-)hHL mice relative to hl(-/-)ciHL controls. Similarly, energy expenditure was ~10% lower in HL-transgenic mice after adjusting for differences in total body weight. Our results demonstrate that (1) the catalytic function of HL is required to rescue the lean body weight phenotype of hl(-/-) mice; (2) this effect involves complementary changes in both sides of the energy balance equation; and (3) the bridging function alone is insufficient to rescue the lean phenotype of hl(-/-)ciHL mice.

  4. Structure-function relationships of the yeast fatty acid synthase: negative-stain, cryo-electron microscopy, and image analysis studies of the end views of the structure.

    PubMed Central

    Stoops, J K; Kolodziej, S J; Schroeter, J P; Bretaudiere, J P; Wakil, S J

    1992-01-01

    The yeast fatty acid synthase (M(r) = 2.5 x 10(6)) is organized in an alpha 6 beta 6 complex. In these studies, the synthase structure has been examined by negative-stain and cryo-electron microscopy. Side and end views of the structure indicate that the molecule, shaped similar to a prolate ellipsoid, has a high-density band of protein bisecting its major axis. Stained and frozen-hydrated average images of the end views show an excellent concordance and a hexagonal ring having three each alternating egg- and kidney-shaped features with low-protein-density protrusions extending outward from the egg-shaped features. Images also show that the barrel-like structure is not hollow but has a Y-shaped central core, which appears to make contact with the three egg-shaped features. Numerous side views of the structure give good evidence that the beta subunits have an archlike shape. We propose a model for the synthase that has point-group symmetry 32 and six equivalent sites of fatty acid synthesis. The protomeric unit is alpha 2 beta 2. The ends of each of the two archlike beta subunits interact with opposite sides of the two dichotomously arranged disclike alpha subunits. Three such protomeric units form the ring. We propose that the six fatty acid synthesizing centers are composed of two complementary half-alpha subunits and a beta subunit, an arrangement having all the partial activities of the multifunctional enzyme required for fatty acid synthesis. Images PMID:1631160

  5. Structure-Function Studies with the Unique Hexameric Form II Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) from Rhodopseudomonas palustris*

    PubMed Central

    Satagopan, Sriram; Chan, Sum; Perry, L. Jeanne; Tabita, F. Robert

    2014-01-01

    The first x-ray crystal structure has been solved for an activated transition-state analog-bound form II ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This enzyme, from Rhodopseudomonas palustris, assembles as a unique hexamer with three pairs of catalytic large subunit homodimers around a central 3-fold symmetry axis. This oligomer arrangement is unique among all known Rubisco structures, including the form II homolog from Rhodospirillum rubrum. The presence of a transition-state analog in the active site locked the activated enzyme in a “closed” conformation and revealed the positions of critical active site residues during catalysis. Functional roles of two form II-specific residues (Ile165 and Met331) near the active site were examined via site-directed mutagenesis. Substitutions at these residues affect function but not the ability of the enzyme to assemble. Random mutagenesis and suppressor selection in a Rubisco deletion strain of Rhodobacter capsulatus identified a residue in the amino terminus of one subunit (Ala47) that compensated for a negative change near the active site of a neighboring subunit. In addition, substitution of the native carboxyl-terminal sequence with the last few dissimilar residues from the related R. rubrum homolog increased the enzyme's kcat for carboxylation. However, replacement of a longer carboxyl-terminal sequence with termini from either a form III or a form I enzyme, which varied both in length and sequence, resulted in complete loss of function. From these studies, it is evident that a number of subtle interactions near the active site and the carboxyl terminus account for functional differences between the different forms of Rubiscos found in nature. PMID:24942737

  6. Structural-functional characterization of the cathodic haemoglobin of the conger eel Conger conger: molecular modelling study of an additional phosphate-binding site.

    PubMed Central

    Pellegrini, Mariagiuseppina; Giardina, Bruno; Verde, Cinzia; Carratore, Vito; Olianas, Alessandra; Sollai, Luigi; Sanna, Maria T; Castagnola, Massimo; di Prisco, Guido

    2003-01-01

    The protein sequence data for the alpha- and beta-chains have been deposited in the SWISS-PROT and TrEMBL protein knowledgebase under the accession numbers P83479 and P83478 respectively. The Conger conger (conger eel) haemoglobin (Hb) system is made of three components, one of which, the so-called cathodic Hb, representing approx. 20% of the total pigment, has been purified and characterized from both a structural and functional point of view. Stripped Hb showed a reverse Bohr effect, high oxygen affinity and slightly low cooperativity in the absence of any effector. Addition of saturating GTP strongly influences the pH dependence of the oxygen affinity, since the reverse Bohr effect, observed under stripped conditions, is converted into a small normal Bohr effect. A further investigation of the GTP effect on oxygen affinity, carried out by fitting its titration curve, demonstrated the presence of two independent binding sites. Therefore, on the basis of the amino acid sequence of the alpha- and beta-chains, which have been determined, a computer modelling study has been performed. The data suggest that C. conger cathodic Hb may bind organic phosphates at two distinct binding sites located along the central cavity of the tetramer by hydrogen bonds and/or electrostatic interactions with amino acid residues of both chains, which have been identified. Among these residues, the two Lys-alpha(G6) (where the letter refers to the haemoglobin helix and the number to the amino acid position in the helix) appear to have a key role in the GTP movement from the external binding region to the internal central cavity of the tetrameric molecule. PMID:12646043

  7. Proton structure functions at small x

    SciTech Connect

    Hentschinski, Martin

    2015-11-03

    Proton structure functions are measured in electron-proton collision through inelastic scattering of virtual photons with virtuality Q on protons; x denotes the momentum fraction carried by the struck parton. Proton structure functions are currently described with excellent accuracy in terms of scale dependent parton distribution functions, defined in terms of collinear factorization and DGLAP evolution in Q. With decreasing x however, parton densities increase and are ultimately expected to saturate. In this regime DGLAP evolution will finally break down and non-linear evolution equations w.r.t x are expected to take over. In the first part of the talk we present recent result on an implementation of physical DGLAP evolution. Unlike the conventional description in terms of parton distribution functions, the former describes directly the Q dependence of the measured structure functions. It is therefore physical insensitive to factorization scheme and scale ambiguities. It therefore provides a more stringent test of DGLAP evolution and eases the manifestation of (non-linear) small x effects. It however requires a precise measurement of both structure functions F2 and FL, which will be only possible at future facilities, such as an Electron Ion Collider. In the second part we present a recent analysis of the small x region of the combined HERA data on the structure function F2. We demonstrate that (linear) next-to-leading order BFKL evolution describes the effective Pomeron intercept, determined from the combined HERA data, once a resummation of collinear enhanced terms is included and the renormalization scale is fixed using the BLM optimal scale setting procedure. We also provide a detailed description of the Q and x dependence of the full structure functions F2 in the small x region, as measured at HERA. As a result, predictions for the structure function FL are found to be in agreement with the existing HERA

  8. Proton structure functions at small x

    DOE PAGES

    Hentschinski, Martin

    2015-11-03

    Proton structure functions are measured in electron-proton collision through inelastic scattering of virtual photons with virtuality Q on protons; x denotes the momentum fraction carried by the struck parton. Proton structure functions are currently described with excellent accuracy in terms of scale dependent parton distribution functions, defined in terms of collinear factorization and DGLAP evolution in Q. With decreasing x however, parton densities increase and are ultimately expected to saturate. In this regime DGLAP evolution will finally break down and non-linear evolution equations w.r.t x are expected to take over. In the first part of the talk we present recentmore » result on an implementation of physical DGLAP evolution. Unlike the conventional description in terms of parton distribution functions, the former describes directly the Q dependence of the measured structure functions. It is therefore physical insensitive to factorization scheme and scale ambiguities. It therefore provides a more stringent test of DGLAP evolution and eases the manifestation of (non-linear) small x effects. It however requires a precise measurement of both structure functions F2 and FL, which will be only possible at future facilities, such as an Electron Ion Collider. In the second part we present a recent analysis of the small x region of the combined HERA data on the structure function F2. We demonstrate that (linear) next-to-leading order BFKL evolution describes the effective Pomeron intercept, determined from the combined HERA data, once a resummation of collinear enhanced terms is included and the renormalization scale is fixed using the BLM optimal scale setting procedure. We also provide a detailed description of the Q and x dependence of the full structure functions F2 in the small x region, as measured at HERA. As a result, predictions for the structure function FL are found to be in agreement with the existing HERA data.« less

  9. In Situ Oxidation of Liquid Trichloroethylene by Permanganate Solutions: Preliminary Results of Column Studies

    SciTech Connect

    Schroth, Martin H.; Oostrom, Mart; Wietsma, Thomas W.; Istok, Jonathan D.; H.J. Morel-Seytoux

    2000-01-11

    In situ oxidation of liquid trichloroethylene by permanganate solutions: Preliminary results of column studies. In: Proceedings of the 19th American Geophysical Union Hydrology Days, H. J. Morel-Seytoux, ed., pp. 411-420. Hydrology Days Pub., Atherton, Ca.

  10. Xenon Implantation in Nanodiamonds: In Situ Transmission Electron Microscopy Study and Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Shiryaev, A. A.; Hinks, J.; Marks, N.; Greaves, G.; Donnelly, S.; Fisenko, A. V.; Kiwi, M.

    2016-08-01

    We present results of the first investigation of the Xe implantation process into nanodiamonds of various sizes studied in situ in transmission electron microscope (TEM), complemented by advanced molecular dynamics simulations.

  11. Crustacean neuropeptides: structures, functions and comparative aspects.

    PubMed

    Keller, R

    1992-05-15

    In this article, an attempt is made to review the presently known, completely identified crustacean neuropeptides with regard to structure, function and distribution. Probably the most important progress has been made in the elucidation of a novel family of large peptides from the X-organ-sinus gland system which includes crustacean hyperglycemic hormone (CHH), putative molt-inhibiting hormone (MIH) and vitellogenesis (= gonad)-inhibiting hormone (VIH). These peptides have so far only been found in crustaceans. Renewed interest in the neurohemal pericardial organs has led to the identification of a number of cardioactive/myotropic neuropeptides, some of them unique to crustaceans. Important contributions have been made by immunocytochemical mapping of peptidergic neurons in the nervous system, which has provided evidence for a multiple role of several neuropeptides as neurohormones on the one hand and as local transmitters or modulators on the other. This has been corroborated by physiological studies. The long-known chromatophore-regulating hormones, red pigment concentrating hormone (RPCH) and pigment-dispending hormone (PDH), have been placed in a broader perspective by the demonstration of an additional role as local neuromodulators. The scope of crustacean neuropeptide research has thus been broadened considerably during the last years.

  12. Sorbitol dehydrogenase: structure, function and ligand design.

    PubMed

    El-Kabbani, O; Darmanin, C; Chung, R P-T

    2004-02-01

    Sorbitol dehydrogenase (SDH), a member of the medium-chain dehydrogenase/reductase protein family and the second enzyme of the polyol pathway of glucose metabolism, converts sorbitol to fructose strictly using NAD(+) as coenzyme. SDH is expressed almost ubiquitously in all mammalian tissues. The enzyme has attracted considerable interest due to its implication in the development of diabetic complications and thus its tertiary structure may facilitate the development of drugs for the treatment of diabetes sufferers. Modelling studies suggest that SDH is structurally homologous to mammalian alcohol dehydrogenase with respect to conserved zinc binding motif and a hydrophobic substrate-binding pocket. Recently, the three-dimensional (3-D) structure of a mammalian SDH was solved, and it was found that while the overall 3-D structures of SDH and alcohol dehydrogenase are similar, the zinc coordination in the active sites of the two enzymes is different. The available structural and biochemical information of SDH are currently being utilized in a structure-based approach to develop drugs for the treatment or prevention of the complications of diabetes. This review provides an overview of the recent advances in the structure, function and drug development fields of sorbitol dehydrogenase.

  13. MOLAB, a Mobile Laboratory for In Situ Non-Invasive Studies in Arts and Archaeology

    NASA Astrophysics Data System (ADS)

    Brunetti, B. G.; Matteini, Mauro; Miliani, C.; Pezzati, L.; Pinna, D.

    Mobile laboratory (MOLAB) is a unique joint collection of portable equipment for non-destructive in situ measurements. MOLAB activities are carried out within the frame of the Eu-ARTECH Integrated Infrastructure Initiative of the sixth F.P. In situ measurement is quite useful because it eliminates any risk connected to moving artworks or other precious objects to a laboratory. MOLAB instruments are accessible to European researchers through a peer-review selection of proposals. Starting from July 2004, MOLAB enabled non-destructive in situ studies of many precious artworks, such as paintings by Perugino, Raphael and Leonardo.

  14. In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy

    SciTech Connect

    Bertram, F. Evertsson, J.; Messing, M. E.; Mikkelsen, A.; Lundgren, E.; Zhang, F.; Pan, J.; Carlà, F.; Nilsson, J.-O.

    2014-07-21

    We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

  15. Leveraging enzyme structure-function relationships for functional inference and experimental design: the structure-function linkage database.

    PubMed

    Pegg, Scott C-H; Brown, Shoshana D; Ojha, Sunil; Seffernick, Jennifer; Meng, Elaine C; Morris, John H; Chang, Patricia J; Huang, Conrad C; Ferrin, Thomas E; Babbitt, Patricia C

    2006-02-28

    The study of mechanistically diverse enzyme superfamilies-collections of enzymes that perform different overall reactions but share both a common fold and a distinct mechanistic step performed by key conserved residues-helps elucidate the structure-function relationships of enzymes. We have developed a resource, the structure-function linkage database (SFLD), to analyze these structure-function relationships. Unique to the SFLD is its hierarchical classification scheme based on linking the specific partial reactions (or other chemical capabilities) that are conserved at the superfamily, subgroup, and family levels with the conserved structural elements that mediate them. We present the results of analyses using the SFLD in correcting misannotations, guiding protein engineering experiments, and elucidating the function of recently solved enzyme structures from the structural genomics initiative. The SFLD is freely accessible at http://sfld.rbvi.ucsf.edu.

  16. In situ studies of microbial inactivation during high pressure processing

    NASA Astrophysics Data System (ADS)

    Maldonado, Jose Antonio; Schaffner, Donald W.; Cuitiño, Alberto M.; Karwe, Mukund V.

    2016-01-01

    High pressure processing (HPP) has been shown to reduce microbial concentration in foods. The mechanisms of microbial inactivation by HPP have been associated with damage to cell membranes. The real-time response of bacteria to HPP was measured to elucidate the mechanisms of inactivation, which can aid in designing more effective processes. Different pressure cycling conditions were used to expose Enterobacter aerogenes cells to HPP. Propidium iodide (PI) was used as a probe, which fluoresces after penetrating cells with damaged membranes and binding with nucleic acids. A HPP vessel with sapphire windows was used for measuring fluorescence in situ. Membrane damage was detected during pressurization and hold time, but not during depressurization. The drop in fluorescence was larger than expected after pressure cycles at higher pressure and longer times. This indicated possible reversible disassociation of ribosomes resulting in additional binding of PI to exposed RNA under pressure and its release after depressurization.

  17. In situ Raman cell for high pressure and temperature studies of metal and complex hydrides.

    PubMed

    Domènech-Ferrer, Roger; Ziegs, Frank; Klod, Sabrina; Lindemann, Inge; Voigtländer, Ralf; Dunsch, Lothar; Gutfleisch, Oliver

    2011-04-15

    A novel cell for in situ Raman studies at hydrogen pressures up to 200 bar and at temperatures as high as 400 °C is presented. This device permits in situ monitoring of the formation and decomposition of chemical structures under high pressure via Raman scattering. The performance of the cell under extreme conditions is stable as the design of this device compensates much of the thermal expansion during heating which avoids defocusing of the laser beam. Several complex and metal hydrides were analyzed to demonstrate the advantageous use of this in situ cell. Temperature calibration was performed by monitoring the structural phase transformation and melting point of LiBH(4). The feasibility of the cell in hydrogen atmosphere was confirmed by in situ studies of the decomposition of NaAlH(4) with added TiCl(3) at different hydrogen pressures and the decomposition and rehydrogenation of MgH(2) and LiNH(2).

  18. Structural Functionalism as a Heuristic Device.

    ERIC Educational Resources Information Center

    Chilcott, John H.

    1998-01-01

    Argues that structural functionalism as a method for conducting fieldwork and as a format for the analysis of ethnographic data remains a powerful model, one that is easily understood by professional educators. As a heuristic device, functionalist theory can help in the solution of a problem that is otherwise incapable of theoretical…

  19. Feminine Faces of Leadership: Beyond Structural- Functionalism?

    ERIC Educational Resources Information Center

    Fennell, Hope-Arlene

    1999-01-01

    Reviews four philosophical leadership perspectives: structural-functionalism, constructivism, critical theory, and feminism. Explores the leadership phenomenon through the eyes of six women principals. Although the behaviors of all six fall within a structural-functionalist perspective, each is attempting to construct inclusive, positive, and…

  20. 2004 Structural, Function and Evolutionary Genomics

    SciTech Connect

    Douglas L. Brutlag Nancy Ryan Gray

    2005-03-23

    This Gordon conference will cover the areas of structural, functional and evolutionary genomics. It will take a systematic approach to genomics, examining the evolution of proteins, protein functional sites, protein-protein interactions, regulatory networks, and metabolic networks. Emphasis will be placed on what we can learn from comparative genomics and entire genomes and proteomes.

  1. Alterations in juvenile flatfish gill epithelia induced by sediment-bound toxicants: A comparative in situ and ex situ study.

    PubMed

    Martins, Carla; Alves de Matos, António P; Costa, Maria H; Costa, Pedro M

    2015-12-01

    Juvenile Solea senegalensis were exposed in the laboratory (ex situ) and field (in situ) to different sediments of a moderately impacted estuary (the Sado, Portugal) for 28 days. A qualitative histopathological screening yielded scant lesions to gills, albeit alterations such as epithelial hyperplasia being evident and more frequent in fish exposed ex situ. Fully quantitative traits, namely chloride and goblet cell count and size revealed differences between the two bioassay approaches, with ex situ experiments likely enhancing bioavailability of toxicants. Chloride cells endured autolytic processes that could, at least in part, relate to contamination by mixed metals and polycyclic aromatic hydrocarbons (PAHs). Goblet cells did not reveal changes in the chemistry of mucous. Still, their number and size was reduced in fish exposed ex situ to the sediments most contaminated by PAHs, with evidence for adaptation. Also, copper histochemistry revealed the potential role of mucocytes in the regulation of metals.

  2. In situ quantitative study of nanoscale triboelectrification and patterning.

    PubMed

    Zhou, Yu Sheng; Liu, Ying; Zhu, Guang; Lin, Zong-Hong; Pan, Caofeng; Jing, Qingshen; Wang, Zhong Lin

    2013-06-12

    By combining contact-mode atomic force microscopy (AFM) and scanning Kevin probe microscopy (SKPM), we demonstrated an in situ method for quantitative characterization of the triboelectrification process at the nanoscale. We systematically characterized the triboelectric charge distribution, multifriction effect on charge transfer, as well as subsequent charge diffusion on the dielectric surface: (i) the SiO2 surface can be either positively or negatively charged through triboelectric process using Si-based AFM probes with and without Pt coating, respectively; (ii) the triboelectric charges accumulated from multifriction and eventually reached to saturated concentrations of (-150 ± 8) μC/m(2) and (105 ± 6) μC/m(2), respectively; (iii) the charge diffusion coefficients on SiO2 surface were measured to be (1.10 ± 0.03) × 10(-15) m(2)/s for the positive charge and (0.19 ± 0.01) × 10(-15) m(2)/s for the negative charges. These quantifications will facilitate a fundamental understanding about the triboelectric and de-electrification process, which is important for designing high performance triboelectric nanogenerators. In addition, we demonstrated a technique for nanopatterning of surface charges without assistance of external electric field, which has a promising potential application for directed self-assembly of charged nanostructures for nanoelectronic devices.

  3. Miniaturized Environmental Scanning Electron Microscope for In Situ Planetary Studies

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica; Abbott, Terry; Medley, Stephanie; Gregory, Don; Thaisen, Kevin; Taylor , Lawrence; Ramsey, Brian; Jerman, Gregory; Sampson, Allen; Harvey, Ralph

    2010-01-01

    The exploration of remote planetary surfaces calls for the advancement of low power, highly-miniaturized instrumentation. Instruments of this nature that are capable of multiple types of analyses will prove to be particularly useful as we prepare for human return to the moon, and as we continue to explore increasingly remote locations in our Solar System. To this end, our group has been developing a miniaturized Environmental-Scanning Electron Microscope (mESEM) capable of remote investigations of mineralogical samples through in-situ topographical and chemical analysis on a fine scale. The functioning of an SEM is well known: an electron beam is focused to nanometer-scale onto a given sample where resulting emissions such as backscattered and secondary electrons, X-rays, and visible light are registered. Raster scanning the primary electron beam across the sample then gives a fine-scale image of the surface topography (texture), crystalline structure and orientation, with accompanying elemental composition. The flexibility in the types of measurements the mESEM is capable of, makes it ideally suited for a variety of applications. The mESEM is appropriate for use on multiple planetary surfaces, and for a variety of mission goals (from science to non-destructive analysis to ISRU). We will identify potential applications and range of potential uses related to planetary exploration. Over the past few of years we have initiated fabrication and testing of a proof-of-concept assembly, consisting of a cold-field-emission electron gun and custom high-voltage power supply, electrostatic electron-beam focusing column, and scanning-imaging electronics plus backscatter detector. Current project status will be discussed. This effort is funded through the NASA Research Opportunities in Space and Earth Sciences - Planetary Instrument Definition and Development Program.

  4. Experimental study on neptunium migration under in situ geochemical conditions

    NASA Astrophysics Data System (ADS)

    Kumata, M.; Vandergraaf, T. T.

    1998-12-01

    Results are reported for migration experiments performed with Np under in situ geochemical conditions over a range of groundwater flow rates in columns of crushed rock in a specially designed facility at the 240-level of the Underground Research Laboratory (URL) near Pinawa, Manitoba, Canada. This laboratory is situated in an intrusive granitic rock formation, the Lac du Bonnet batholith. Highly altered granitic rock and groundwater were obtained from a major subhorizontal fracture zone at a depth of 250 m in the URL. The granite was wet-crushed and wet-sieved with groundwater from this fracture zone. The 180-850-μm size fraction was selected and packed in 20-cm long, 2.54-cm in diameter Teflon™-lined stainless steel columns. Approximately 30-ml vols of groundwater containing 3HHO and 237Np were injected into the columns at flow rates of 0.3, 1, and 3 ml/h, followed by elution with groundwater, obtained from the subhorizontal fracture, at the same flow rates, for a period of 95 days. Elution profiles for 3HHO were obtained, but no 237Np was detected in the eluted groundwater. After terminating the migration experiments, the columns were frozen, the column material was removed and cut into twenty 1-cm thick sections and each section was analyzed by gamma spectrometry. Profiles of 237Np were obtained for the three columns. A one-dimensional transport model was fitted to the 3HHO breakthrough curves to obtain flow parameters for this experiment. These flow parameters were in turn applied to the 237Np concentration profiles in the columns to produce sorption and dispersion coefficients for Np. The results show a strong dependence of retardation factors ( Rf) on flow rate. The decrease in the retarded velocity of the neptunium ( Vn) varied over one order of magnitude under the geochemical conditions for these experiments.

  5. Dynamic versus Static Hadronic Structure Functions

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2009-01-09

    'Static' structure functions are the probabilistic distributions computed from the square of the light-front wavefunctions of the target hadron. In contrast, the 'dynamic' structure functions measured in deep inelastic lepton-hadron scattering include the effects of rescattering associated with the Wilson line. Initial- and final-state rescattering, neglected in the parton model, can have a profound effect in QCD hard-scattering reactions, producing single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam-Tung relation in Drell-Yan reactions, nuclear shadowing, and non-universal nuclear antishadowing|novel leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also review how 'direct' higher-twist processes--where a proton is produced in the hard subprocess itself--can explain the anomalous proton-to-pion ratio seen in high centrality heavy ion collisions.

  6. Structure function calculations for Ostwald Ripening processes

    NASA Technical Reports Server (NTRS)

    Hassan, Razi A.

    1990-01-01

    A program for computing the structure function for configurations involved in Ostwald Ripening was written. The basic algorithms are derived from a mathematical analysis of a two-dimensional model system developed by Bortz, et. al. (1974). While it is expected that the values form the computer simulations will reflect Ostwald Ripening, at this point the program is still being tested. Some preliminary runs seem to justify the expectations.

  7. In situ heavy ion irradiation studies of nanopore shrinkage and enhanced radiation tolerance of nanoporous Au

    PubMed Central

    Li, Jin; Fan, C.; Ding, J.; Xue, S.; Chen, Y.; Li, Q.; Wang, H.; Zhang, X.

    2017-01-01

    High energy particle radiations induce severe microstructural damage in metallic materials. Nanoporous materials with a giant surface-to-volume ratio may alleviate radiation damage in irradiated metallic materials as free surface are defect sinks. Here we show, by using in situ Kr ion irradiation in a transmission electron microscope at room temperature, that nanoporous Au indeed has significantly improved radiation tolerance comparing with coarse-grained, fully dense Au. In situ studies show that nanopores can absorb and eliminate a large number of radiation-induced defect clusters. Meanwhile, nanopores shrink (self-heal) during radiation, and their shrinkage rate is pore size dependent. Furthermore, the in situ studies show dose-rate-dependent diffusivity of defect clusters. This study sheds light on the design of radiation-tolerant nanoporous metallic materials for advanced nuclear reactor applications. PMID:28045044

  8. Tissue microarray (TMA) technology: miniaturized pathology archives for high-throughput in situ studies.

    PubMed

    Bubendorf, L; Nocito, A; Moch, H; Sauter, G

    2001-09-01

    Tissue microarray (TMA) technology allows a massive acceleration of studies correlating molecular in situ findings with clinico-pathological information. In this technique, cylindrical tissue samples are taken from up to 1000 different archival tissue blocks and subsequently placed into one empty 'recipient' paraffin block. Sections from TMA blocks can be used for all different types of in situ tissue analyses including immunohistochemistry and in situ hybridization. Multiple studies have demonstrated that findings obtained on TMAs are highly representative of their donor tissues, despite the small size of the individual specimens (diameter 0.6 mm). It is anticipated that TMAs will soon become a widely used tool for all types of tissue-based research. The availability of TMAs containing highly characterized tissues will enable every researcher to perform studies involving thousands of tumours rapidly. Therefore, TMAs will lead to a significant acceleration of the transition of basic research findings into clinical applications.

  9. In situ heavy ion irradiation studies of nanopore shrinkage and enhanced radiation tolerance of nanoporous Au

    NASA Astrophysics Data System (ADS)

    Li, Jin; Fan, C.; Ding, J.; Xue, S.; Chen, Y.; Li, Q.; Wang, H.; Zhang, X.

    2017-01-01

    High energy particle radiations induce severe microstructural damage in metallic materials. Nanoporous materials with a giant surface-to-volume ratio may alleviate radiation damage in irradiated metallic materials as free surface are defect sinks. Here we show, by using in situ Kr ion irradiation in a transmission electron microscope at room temperature, that nanoporous Au indeed has significantly improved radiation tolerance comparing with coarse-grained, fully dense Au. In situ studies show that nanopores can absorb and eliminate a large number of radiation-induced defect clusters. Meanwhile, nanopores shrink (self-heal) during radiation, and their shrinkage rate is pore size dependent. Furthermore, the in situ studies show dose-rate-dependent diffusivity of defect clusters. This study sheds light on the design of radiation-tolerant nanoporous metallic materials for advanced nuclear reactor applications.

  10. Structure-function relations of carbohydrates by neoglycolipid arrays.

    PubMed

    Huang, Gang-Liang; Huang, Hua-Liang; Zhang, Hou-Cheng; Wang, Peng-George

    2006-06-01

    The work presented herein is a new noncovalent glycoarray assembly method for microplates created by simply mixing together a carbohydrate and a tetradecylamine. alpha-D-Mannopyranoside, alpha-D-glucopyranoside, and alpha-D-galactopyranoside were utilized in model studies and product formations were detected by lectin binding. The method can be extended to study the steric hindrance effect of carbohydrate-protein interactions, namely the structure-function relations of carbohydrates.

  11. In situ and ex situ studies of materials with relevance to electrochemical energy storage and energy generation

    NASA Astrophysics Data System (ADS)

    Luo, Yu

    Surface analytical techniques have been employed for the preparation and characterization of modified surfaces of relevance to electrochemical energy storage and generation in ultrahigh vacuum environments. Complementary in situ spectroscopic studies were also performed using Raman microscopy for monitoring static and dynamic aspects of Li intercalation and deintercalation into transition metal oxides and graphitic materials. The most important conclusions emerging from this investigation can be summarized as follows: (i) Ruthenium-modified Pt(100) surfaces of very high purity and controlled stoichiometry were prepared in ultrahigh vacuum (UHV) by irradiating Ru3(CO)12 films condensed on cold Pt substrates at 150 K with X-rays, and subsequent annealing at ca. 620 K. Exposure of non-annealed Ru(thetaRu ≥0.22)/Pt(100) to large exposures of CO at ca. 200 K, yielded smaller theta CO, and temperature programmed desorption peaks ca. 50 K lower than those observed for bare Pt(100). (ii) Raman spectra of isolated single particles of technical grade LiMn2O4 embedded in Au foils were recorded in situ in 1M LiPF6 in EC/DMC solutions in real time during a voltammetric scan using a Raman microscope. Similar experiments involving single KS-44 carbon particles (8--50 mum in diameter) embedded into thermally annealed Ni foils in 1M LiClO4, ethylene carbonate (EC) diethyl carbonate (DEC) solutions allowed the average concentration of Li+ within the volume of the particle probed by the laser beam following application of a potential step to be monitored spectroscopically in real time. Analysis of these transient data yielded deintercalation time constants for Li+ for dilute stage 1 phase consistent with reported values of Li+ diffusion coefficients within graphitic materials. A new Raman band ascribed to bounding graphite layers was found upon continuous cycling of single KS-44 particles deep into the Li+-intercalation region. This feature was attributed to chemical modifications

  12. Structure-function relationships of human meniscus.

    PubMed

    Danso, Elvis K; Oinas, Joonas M T; Saarakkala, Simo; Mikkonen, Santtu; Töyräs, Juha; Korhonen, Rami K

    2017-03-01

    , caused by the collagen network and fluid, may be strongly influenced by tissue osmotic swelling from the deep meniscus caused by the increased PG content, leading to increased collagen fibril tension. These nonlinear biomechanical properties are suggested to be further amplified by higher collagen content at all tissue depths and superficial collagen fibril orientation. However, these structure-function relationships are suggested to be highly site-specific.

  13. In Situ TEM Nanoindentation Studies on Stress-Induced Phase Transformations in Metallic Materials

    SciTech Connect

    Liu, Y.; Wang, H.; Zhang, X.

    2015-11-30

    Though abundant phase transformations are in general thermally driven processes, there are many examples wherein stresses can induce phase transformations. We applied numerous in situ techniques, such as in situ x-ray diffraction and neutron diffraction in order to reveal phase transformations. Recently, an in situ nanoindentation technique coupled with transmission electron microscopy demonstrated the capability to directly correlating stresses with phase transformations and microstructural evolutions at a submicron length scale. We briefly review in situ studies on stress-induced diffusional and diffusionless phase transformations in amorphous CuZrAl alloy and NiFeGa shape memory alloy. Moreover, in the amorphous CuZrAl, in situ nanoindentation studies show that the nucleation of nanocrystals (a diffusional process) occurs at ultra-low stresses manifested by a prominent stress drop. In the NiFeGa shape memory alloy, two distinctive types of martensitic (diffusionless) phase transformations accompanied by stress plateaus are observed, including a reversible gradual phase transformation at low stress levels, and an irreversible abrupt phase transition at higher stress levels.

  14. In Situ TEM Nanoindentation Studies on Stress-Induced Phase Transformations in Metallic Materials

    DOE PAGES

    Liu, Y.; Wang, H.; Zhang, X.

    2015-11-30

    Though abundant phase transformations are in general thermally driven processes, there are many examples wherein stresses can induce phase transformations. We applied numerous in situ techniques, such as in situ x-ray diffraction and neutron diffraction in order to reveal phase transformations. Recently, an in situ nanoindentation technique coupled with transmission electron microscopy demonstrated the capability to directly correlating stresses with phase transformations and microstructural evolutions at a submicron length scale. We briefly review in situ studies on stress-induced diffusional and diffusionless phase transformations in amorphous CuZrAl alloy and NiFeGa shape memory alloy. Moreover, in the amorphous CuZrAl, in situ nanoindentationmore » studies show that the nucleation of nanocrystals (a diffusional process) occurs at ultra-low stresses manifested by a prominent stress drop. In the NiFeGa shape memory alloy, two distinctive types of martensitic (diffusionless) phase transformations accompanied by stress plateaus are observed, including a reversible gradual phase transformation at low stress levels, and an irreversible abrupt phase transition at higher stress levels.« less

  15. How to design in situ studies: an evaluation of experimental protocols

    PubMed Central

    Sung, Young-Hye; Kim, Hae-Young; Son, Ho-Hyun

    2014-01-01

    Objectives Designing in situ models for caries research is a demanding procedure, as both clinical and laboratory parameters need to be incorporated in a single study. This study aimed to construct an informative guideline for planning in situ models relevant to preexisting caries studies. Materials and Methods An electronic literature search of the PubMed database was performed. A total 191 of full articles written in English were included and data were extracted from materials and methods. Multiple variables were analyzed in relation to the publication types, participant characteristics, specimen and appliance factors, and other conditions. Frequencies and percentages were displayed to summarize the data and the Pearson's chi-square test was used to assess a statistical significance (p < 0.05). Results There were many parameters commonly included in the majority of in situ models such as inclusion criteria, sample sizes, sample allocation methods, tooth types, intraoral appliance types, sterilization methods, study periods, outcome measures, experimental interventions, etc. Interrelationships existed between the main research topics and some parameters (outcome measures and sample allocation methods) among the evaluated articles. Conclusions It will be possible to establish standardized in situ protocols according to the research topics. Furthermore, data collaboration from comparable studies would be enhanced by homogeneous study designs. PMID:25110639

  16. A no extensive statistical model for the nucleon structure function

    SciTech Connect

    Trevisan, Luis A.; Mirez, Carlos

    2013-03-25

    We studied an application of nonextensive thermodynamics to describe the structure function of nucleon, in a model where the usual Fermi-Dirac and Bose-Einstein energy distribution were replaced by the equivalent functions of the q-statistical. The parameters of the model are given by an effective temperature T, the q parameter (from Tsallis statistics), and two chemical potentials given by the corresponding up (u) and down (d) quark normalization in the nucleon.

  17. In-situ study of interconnect failures by electromigration inside a scanning electron microscope

    SciTech Connect

    Wetzig, Klaus; Wendrock, Horst; Buerke, Axel; Koetter, Thomas

    1999-11-03

    The influence of microstructure on electromigration damage of Al and Cu interconnects with different width and morphology was studied. At first, grain boundaries and local grain orientations before electromigration were registered and correlated with defect places. The investigations focussed on in-situ electromigration tests inside a SEM under accelerated loading conditions, on the in-situ observation of defect formation, and on orientation measurements at the interconnect grains. The position of individual grain boundaries and the misorientation of their neighbored grains seem to be decisive factors for the interconnect failure because of different diffusivities. Whereas the failure behavior of polycrystalline interconnects is sufficiently understood, bamboo structures require further investigations.

  18. In situ study on the reorientation of polymer chains in operating polymer diodes

    NASA Astrophysics Data System (ADS)

    Guo, Tzung-Fang; Yang, Yang

    2002-01-01

    A reflection-absorption Fourier-transform infrared spectroscopy experiment has been designed to in situ monitor poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV)-based polymer light-emitting diodes under stress test. This method enables the in situ study of the co-relation between device performance and the conformational transformation of a conjugated polymer. The experimental results indicate that the plane of the conjugated π-electron cloud in MEH-PPV tends to align parallel to the substrate. This rearrangement enhances the π-π electron coupling and lowers the device operating voltage under high current densities.

  19. Sample environment for in situ synchrotron corrosion studies of materials in extreme environments

    SciTech Connect

    Elbakhshwan, Mohamed S.; Gill, Simerjeet K.; Motta, Arthur T.; Weidner, Randy; Anderson, Thomas; Ecker, Lynne E.

    2016-10-25

    A new in situ sample environment has been designed and developed to study the interfacial interactions of nuclear cladding alloys with high temperature steam. The sample environment is particularly optimized for synchrotron X-ray diffraction (XRD) studies for in situ structural analysis. The sample environment is highly corrosion resistant and can be readily adapted for steam environments. The in situ sample environment design complies with G2 ASTM standards for studying corrosion in zirconium and its alloys and offers remote temperature and pressure monitoring during the in situ data collection. The use of the in situ sample environment is exemplified by monitoring the oxidation of metallic zirconium during exposure to steam at 350°C. Finally, the in situ sample environment provides a powerful tool for fundamental understanding of corrosion mechanisms by elucidating the substoichiometric oxide phases formed during early stages of corrosion, which can provide a better understanding the oxidation process.

  20. Linking stoichiometric homoeostasis with ecosystem structure, functioning and stability.

    PubMed

    Yu, Qiang; Chen, Quansheng; Elser, James J; He, Nianpeng; Wu, Honghui; Zhang, Guangming; Wu, Jianguo; Bai, Yongfei; Han, Xingguo

    2010-11-01

    Ecosystem structure, functioning and stability have been a focus of ecological and environmental sciences during the past two decades. The mechanisms underlying their relationship, however, are not well understood. Based on comprehensive studies in Inner Mongolia grassland, here we show that species-level stoichiometric homoeostasis was consistently positively correlated with dominance and stability on both 2-year and 27-year temporal scales and across a 1200-km spatial transect. At the community level, stoichiometric homoeostasis was also positively correlated with ecosystem function and stability in most cases. Thus, homoeostatic species tend to have high and stable biomass; and ecosystems dominated by more homoeostatic species have higher productivity and greater stability. By modulating organism responses to key environmental drivers, stoichiometric homoeostasis appears to be a major mechanism responsible for the structure, functioning and stability of grassland ecosystems.

  1. Structure Function of Excess Charge in Rock Salt

    NASA Astrophysics Data System (ADS)

    Watanabe, Yusuke; Chiba, Masami; Yasuda, Osamu; Kamijo, Toshio; Chikashige, Yuichi; Kon, Tadashi; Shimizu, Yutaka; Amano, Akio; Takeoka, Yosito; Mori, Satoshi; Ninomiya, Sousuke

    Ultra high-energy (UHE) neutrino (1015 eV <) detection in natural huge rock salt formation has been studied. Radio wave is generated by Askar'yan effect in rock salt. That is caused by the number asymmetry of electrons and positrons (excess charge) in electromagnetic shower from an UHE neutrino. An Electromagnetic shower in rock salt is generated by a computer code of Geant4.5. A modified Greisen parameterization in longitudinal distribution of the shower and a modified Nishimura, Kamata, and Greisen function in lateral distribution of the shower (structure function) are fitted to a space distribution of the excess electrons. The structure function would assist to calculate radio wave emission without using an electromagnetic shower simulation.

  2. Comparison of γZ-structure function models

    SciTech Connect

    Rislow, Benjamin C.

    2013-11-07

    The γZ-box is an important contribution to the proton's weak charge. The γZ-box is calculated dispersively and depends on γZ-structure functions, F{sub 1,2,3}{sup γZ}(x,Q{sup 2}). At present there is no data for these structure functions and they must be modeled by modifying existing fits to electromagnetic data. Each group that has studied the γZ-box used different modifications. The results of the PVDIS experiment at Jefferson Lab may provide a first test of the validity of each group's models. I present details of the different models and their predictions for the PVDIS result.

  3. A-dependence of weak nuclear structure functions

    SciTech Connect

    Haider, H.; Athar, M. Sajjad; Simo, I. Ruiz

    2015-05-15

    Effect of nuclear medium on the weak structure functions F{sub 2}{sup A}(x, Q{sup 2}) and F{sub 3}{sup A}(x, Q{sup 2}) have been studied using charged current (anti)neutrino deep inelastic scattering on various nuclear targets. Relativistic nuclear spectral function which incorporate Fermi motion, binding and nucleon correlations are used for the calculations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, F{sub i}{sup A}/F{sub i}{sup proton} and F{sub i}{sup A}/F{sub i}{sup deuteron}(i=2,3, A={sup 12}C, {sup 16}O, CH and H{sub 2}O) are obtained.

  4. Palladium deuteride formation in the cathode of an electrochemical cell: An in situ neutron diffraction study

    SciTech Connect

    Rotella, F.J.; Richardson, J.W. Jr.; Redey, L.; Felcher, G.P.; Hitterman, R.L.; Kleb, R.

    1991-12-31

    In this report, neutron diffraction of palladium cathodes is utilized to reveal palladium deuteride formation within the crystal structure of the metal. The experiment described in this report demonstrates the efficacy of neutron powder diffraction as a tool for structural studies of metal deuterides/hydrides and the feasibility of in situ diffraction measurements from a working electrochemical cell. (JL)

  5. Palladium deuteride formation in the cathode of an electrochemical cell: An in situ neutron diffraction study

    SciTech Connect

    Rotella, F.J.; Richardson, J.W. Jr.; Redey, L.; Felcher, G.P.; Hitterman, R.L.; Kleb, R.

    1991-01-01

    In this report, neutron diffraction of palladium cathodes is utilized to reveal palladium deuteride formation within the crystal structure of the metal. The experiment described in this report demonstrates the efficacy of neutron powder diffraction as a tool for structural studies of metal deuterides/hydrides and the feasibility of in situ diffraction measurements from a working electrochemical cell. (JL)

  6. Surface phenomena revealed by in situ imaging: studies from adhesion, wear and cutting

    NASA Astrophysics Data System (ADS)

    Viswanathan, Koushik; Mahato, Anirban; Yeung, Ho; Chandrasekar, Srinivasan

    2017-03-01

    Surface deformation and flow phenomena are ubiquitous in mechanical processes. In this work we present an in situ imaging framework for studying a range of surface mechanical phenomena at high spatial resolution and across a range of time scales. The in situ framework is capable of resolving deformation and flow fields quantitatively in terms of surface displacements, velocities, strains and strain rates. Three case studies are presented demonstrating the power of this framework for studying surface deformation. In the first, the origin of stick-slip motion in adhesive polymer interfaces is investigated, revealing a intimate link between stick-slip and surface wave propagation. Second, the role of flow in mediating formation of surface defects and wear particles in metals is analyzed using a prototypical sliding process. It is shown that conventional post-mortem observation and inference can lead to erroneous conclusions with regard to formation of surface cracks and wear particles. The in situ framework is shown to unambiguously capture delamination wear in sliding. Third, material flow and surface deformation in a typical cutting process is analyzed. It is shown that a long-standing problem in the cutting of annealed metals is resolved by the imaging, with other benefits such as estimation of energy dissipation and power from the flow fields. In closure, guidelines are provided for profitably exploiting in situ observations to study large-strain deformation, flow and friction phenomena at surfaces that display a variety of time-scales.

  7. In-Situ Chemical Reduction and Oxidation of VOCs in Groundwater: Groundwater Treatability Studies

    NASA Technical Reports Server (NTRS)

    Keith, Amy; Glasgow, Jason; McCaleh, Rececca C. (Technical Monitor)

    2001-01-01

    This paper presents NASA Marshall Space Flight Center's treatability studies for volatile organic compounds in groundwater. In-Situ groundwater treatment technologies include: 1) Chemical Reduction(Ferox); 2) Chemical Oxidation (Fenton Reagents, Permanganate, and Persulfate); and 3) Thermal (Dynamic Underground Stripping, Six-Phase Heating). This paper is presented in viewgraph form.

  8. The Structure-Function Linkage Database.

    PubMed

    Akiva, Eyal; Brown, Shoshana; Almonacid, Daniel E; Barber, Alan E; Custer, Ashley F; Hicks, Michael A; Huang, Conrad C; Lauck, Florian; Mashiyama, Susan T; Meng, Elaine C; Mischel, David; Morris, John H; Ojha, Sunil; Schnoes, Alexandra M; Stryke, Doug; Yunes, Jeffrey M; Ferrin, Thomas E; Holliday, Gemma L; Babbitt, Patricia C

    2014-01-01

    The Structure-Function Linkage Database (SFLD, http://sfld.rbvi.ucsf.edu/) is a manually curated classification resource describing structure-function relationships for functionally diverse enzyme superfamilies. Members of such superfamilies are diverse in their overall reactions yet share a common ancestor and some conserved active site features associated with conserved functional attributes such as a partial reaction. Thus, despite their different functions, members of these superfamilies 'look alike', making them easy to misannotate. To address this complexity and enable rational transfer of functional features to unknowns only for those members for which we have sufficient functional information, we subdivide superfamily members into subgroups using sequence information, and lastly into families, sets of enzymes known to catalyze the same reaction using the same mechanistic strategy. Browsing and searching options in the SFLD provide access to all of these levels. The SFLD offers manually curated as well as automatically classified superfamily sets, both accompanied by search and download options for all hierarchical levels. Additional information includes multiple sequence alignments, tab-separated files of functional and other attributes, and sequence similarity networks. The latter provide a new and intuitively powerful way to visualize functional trends mapped to the context of sequence similarity.

  9. Confocal microscopy indentation system for studying in situ chondrocyte mechanics.

    PubMed

    Han, Sang-Kuy; Colarusso, Pina; Herzog, Walter

    2009-10-01

    Chondrocytes synthesize extracellular matrix molecules, thus they are essential for the development, adaptation and maintenance of articular cartilage. Furthermore, it is well accepted that the biosynthetic activity of chondrocytes is influenced by the mechanical environment. Therefore, their response to mechanical stimuli has been studied extensively. Much of the knowledge in this area of research has been derived from testing of isolated cells, cartilage explants, and fixed cartilage specimens: systems that differ in important aspects from chondrocytes embedded in articular cartilage and observed during loading conditions. In this study, current model systems have been improved by working with the intact cartilage in real time. An indentation system was designed on a confocal microscope that allows for simultaneous loading and observation of chondrocytes in their native environment. Cell mechanics were then measured under precisely controlled loading conditions. The indentation system is based on a light transmissible cylindrical glass indentor of 0.17 mm thickness and 1.64 mm diameter that is aligned along the focal axis of the microscope and allows for real time observation of live cells in their native environment. The system can be used to study cell deformation and biological responses, such as calcium sparks, while applying prescribed loads on the cartilage surface. It can also provide novel information on the relationship between cell loading and cartilage adaptive/degenerative processes in the intact tissue.

  10. IN SITU INFRARED STUDY OF CATALYTIC DECOMPOSITION OF NO

    SciTech Connect

    KHALID ALMUSAITEER; RAM KRISHNAMURTHY; STEVEN S.C. CHUANG

    1998-08-18

    The growing concerns for the environment and increasingly stringent standards for NO emission have presented a major challenge to control NO emissions from electric utility plants and automobiles. Catalytic decomposition of NO is the most attractive approach for the control of NO emission for its simplicity. Successful development of an effective catalyst for NO decomposition will greatly decrease the equipment and operation cost of NO control. Due to lack of understanding of the mechanism of NO decomposition, efforts on the search of an effective catalyst have been unsuccessful. Scientific development of an effective catalyst requires fundamental understanding of the nature of active site, the rate-limiting step, and an approach to prolong the life of the catalyst. Research is proposed to study the reactivity of adsorbates for the direct NO decomposition and to investigate the feasibility of two novel approaches for improving catalyst activity and resistance to sintering. The first approach is the use of silanation to stabilize metal crystallites and supports for Cu-ZSM-5 and promoted Pt catalysts; the second is utilization of oxygen spillover and desorption to enhance NO decomposition activity. An innovative infrared reactor system will be used to observe and determine the dynamic behavior and the reactivity of adsorbates during NO decomposition, oxygen spillover, and silanation. A series of experiments including X-ray diffraction, temperature programmed desorption, temperature programmed reaction, X-ray photoelectron spectroscopy will be used to characterized the catalysts. The information obtained from this study will provide a scientific basis for developing an effective catalyst for the NO decomposition under practical flue gas conditions.

  11. An in situ sample environment reaction cell for spatially resolved x-ray absorption spectroscopy studies of powders and small structured reactors

    SciTech Connect

    Zhang, Chu; Gustafson, Johan; Merte, Lindsay R.; Evertsson, Jonas; Norén, Katarina; Carlson, Stefan; Svensson, Håkan; Carlsson, Per-Anders

    2015-03-15

    An easy-to-use sample environment reaction cell for X-ray based in situ studies of powders and small structured samples, e.g., powder, pellet, and monolith catalysts, is described. The design of the cell allows for flexible use of appropriate X-ray transparent windows, shielding the sample from ambient conditions, such that incident X-ray energies as low as 3 keV can be used. Thus, in situ X-ray absorption spectroscopy (XAS) measurements in either transmission or fluorescence mode are facilitated. Total gas flows up to about 500 ml{sub n}/min can be fed while the sample temperature is accurately controlled (at least) in the range of 25–500 °C. The gas feed is composed by a versatile gas-mixing system and the effluent gas flow composition is monitored with mass spectrometry (MS). These systems are described briefly. Results from simultaneous XAS/MS measurements during oxidation of carbon monoxide over a 4% Pt/Al{sub 2}O{sub 3} powder catalyst are used to illustrate the system performance in terms of transmission XAS. Also, 2.2% Pd/Al{sub 2}O{sub 3} and 2% Ag − Al{sub 2}O{sub 3} powder catalysts have been used to demonstrate X-ray absorption near-edge structure (XANES) spectroscopy in fluorescence mode. Further, a 2% Pt/Al{sub 2}O{sub 3} monolith catalyst was used ex situ for transmission XANES. The reaction cell opens for facile studies of structure-function relationships for model as well as realistic catalysts both in the form of powders, small pellets, and coated or extruded monoliths at near realistic conditions. The applicability of the cell for X-ray diffraction measurements is discussed.

  12. Cost studies of thermally enhanced in situ soil remediation technologies

    SciTech Connect

    Bremser, J.; Booth, S.R.

    1996-05-01

    This report describes five thermally enhanced technologies that may be used to remediate contaminated soil and water resources. The standard methods of treating these contaminated areas are Soil Vapor Extraction (SVE), Excavate & Treat (E&T), and Pump & Treat (P&T). Depending on the conditions at a given site, one or more of these conventional alternatives may be employed; however, several new thermally enhanced technologies for soil decontamination are emerging. These technologies are still in demonstration programs which generally are showing great success at achieving the expected remediation results. The cost savings reported in this work assume that the technologies will ultimately perform as anticipated by their developers in a normal environmental restoration work environment. The five technologies analyzed in this report are Low Frequency Heating (LF or Ohmic, both 3 and 6 phase AC), Dynamic Underground Stripping (DUS), Radio Frequency Heating (RF), Radio Frequency Heating using Dipole Antennae (RFD), and Thermally Enhanced Vapor Extraction System (TEVES). In all of these technologies the introduction of heat to the formation raises vapor pressures accelerating contaminant evaporation rates and increases soil permeability raising diffusion rates of contaminants. The physical process enhancements resulting from temperature elevations permit a greater percentage of volatile organic compound (VOC) or semi- volatile organic compound (SVOC) contaminants to be driven out of the soils for treatment or capture in a much shorter time period. This report presents the results of cost-comparative studies between these new thermally enhanced technologies and the conventional technologies, as applied to five specific scenarios.

  13. An in situ study of resin-assisted solvothermal metal-organic framework synthesis

    SciTech Connect

    Moorhouse, Saul J.; Wu, Yue; O’Hare, Dermot

    2016-04-15

    A newly developed in situ monochromatic high-energy X-ray diffraction setup was used to investigate the synthesis of MOFs using cation-impregnated polymer resin beads as a ion source. The Co–NDC–DMF (NDC=2,6-naphthalenedicarboxylate; DMF=dimethylformamide) system was investigated, a system which is known to produce at least three distinct frameworks. It was found that the resin-assisted synthesis results in the preferential formation of a topology previously impossible to synthesise in bulk, while the comparable nitrate-salt synthesis appeared to form an alternative phases. It was also found that the resin-assisted synthesis is highly diffusion-controlled. - Graphical abstract: In situ monochromatic high-energy X-ray diffraction study of a MOF synthesis. - Highlights: • Resin-assisted solvothermal MOF synthesis was studied using in situ diffraction. • Full kinetics of reaction can be obtained from in situ data. • Kinetics show that this resin-assisted synthesis is diffusion controlled. • Resin-assisted synthesis enables the production of an alternative bulk phase.

  14. The Spin Structure Function g2

    SciTech Connect

    Rock, Stephen E.

    2003-02-27

    We have measured the spin structure functions g{sub 2}{sup p} and g{sub 2}{sup d} over the kinematic range 0.02 {le} x {le} 0.8 and 0.7 {le} Q{sup 2} {le} 20 GeV{sup 2} by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH{sub 3} and {sup 6}LiD targets. Our measured g{sub 2} approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d{sub 2}{sup p} and d{sub 2}{sup n} are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule. The Efremov-Leader-Teryaev integral is consistent with zero within our measured kinematic range.

  15. Transintestinal secretion of ciprofloxacin, grepafloxacin and sparfloxacin: in vitro and in situ inhibition studies.

    PubMed

    Rodríguez-Ibáñez, M; Nalda-Molina, R; Montalar-Montero, M; Bermejo, M V; Merino, V; Garrigues, T M

    2003-03-01

    The influence of the secretion process on the absorption of ciprofloxacin, grepafloxacin and sparfloxacin has been evaluated by means of inhibition studies. Two well known P-glycoprotein inhibitors (cyclosporine, verapamil), a mixed inhibitor of P-glycoprotein and the organic cation transporter OCT1 (quinidine) and a well established MRP substrate (p-aminohipuric acid) have been selected in order to distinguish the possible carriers implicated. An in situ rat gut perfusion model and CACO-2 permeability studies are used. Both methods suggest the involvement of several types of efflux transporters for every fluoroquinolone. The relevance of the secretory pathway depends on the intrinsic permeability of the quinolone. The in vitro model seems to be more suitable for discriminating mechanisms underlying the absorption process, while in situ studies are less sensitive to inhibition studies.

  16. Structure, Function and Regulation of the Clostridium cellulovorans Cellulosome

    SciTech Connect

    Doi, Roy H

    2008-06-01

    Our major goal for this project (2004-2008) was to obtain an understanding ofthe structure, function, and regulation of the Clostridium cellulovorans cellulosomes. Our specific goals were to select genes for cellulosomal and non-cellulosomal enzymes and characterize their products, to study the synergistic action between cellulosomal and non-cellulosomal enzymes, to study the composition of cellulosomes when cells were grown with different carbon sources, continue our studies on the scaffolding protein and examine heterologous expression of cellulosomal genes in Bacillus subtilis. We fulfilled the specific goals of our proposal.

  17. Structure-function analysis of CYP27B1 and CYP27A1. Studies on mutants from patients with vitamin D-dependent rickets type I (VDDR-I) and cerebrotendinous xanthomatosis (CTX).

    PubMed

    Sawada, N; Sakaki, T; Kitanaka, S; Kato, S; Inouye, K

    2001-12-01

    We have determined eight types of missense mutants of CYP27B1 from Japanese vitamin D-dependent rickets type I (VDDR-I) patients [Kitanaka, S., Takeyama, K., Murayama, A., Sato, T., Okumura, K., Nogami, M., Hasegawa, Y., Niimi, H., Yanagisawa, J., Tanaka, T. & Kato, S. (1998) New England J. Med., 338, 653-661 and Kitanaka, S., Murayama, A., Sakaki, T., Inouye, K., Seino, Y., Fukumoto, S., Shima, M., Yukizane, S., Takayanagi, M., Niimi, H., Takeyama, K. & Kato, S. (1999) J. Clin. Endocrine Metab., 84, 4111-4117]. None of the CYP27B1 mutants showed 1alpha-hydroxylase activity towards 25-hydroxyvitamin D3. Thus, it was assumed that the mutated amino-acid residues play important roles in the 1alpha-hydroxylase activity, such as substrate binding, activation of molecular oxygen, interaction with adrenodoxin, and folding of the cytochrome P450 structure. To examine our hypothesis, we generated various mutants of CYP27B1 and studied their enzymatic properties. In addition, the corresponding mutations were introduced to CYP27A1, which belongs to the same family as CYP27B1. As CYP27A1 showed much higher expression level than CYP27B1 in Escherichia coli, further analysis including heme-binding and substrate-binding was performed with CYP27A1 in place of CYP27B1. Western blot analysis, spectral analysis including reduced CO-difference spectra and substrate-induced difference spectra, and enzymatic analysis of the mutant CYP27A1 gave information on the structure-function relationships of both CYP27A1 and CYP27B1. Although the sequence alignment suggested that Arg107, Gly125, and Pro497 of CYP27B1 might be involved in substrate binding, the experimental data strongly suggested that mutations of these amino-acid residues destroyed the tertiary structure of the substrate-heme pocket. It was also suggested that Arg389 and Arg453 of CYP27B1 were involved in heme-propionate binding, and Asp164 stabilized the four-helix bundle consisting of D, E, I and J helices, possibly by forming

  18. Treatability study to evaluate in situ chlorinated solvent and pesticide bioremediation

    SciTech Connect

    Lige, J.E.; MacFarlane, I.D.; Hundt, T.R.

    1995-12-31

    Exploiting microbial reactions to remediate chlorinated solvents and pesticide contamination appeared to be an attractive remedial alternative for a site located at the Dover Air Force Base in Dover, Delaware. To generate data to evaluate the feasibility of implementing enhanced in situ bioremediation as a remedial technique, a relatively inexpensive and rapid treatability study was designed. Batch microcosm studies were used to mimic in situ redox conditions (oxygenated and unoxygenated) and methanotrophic conditions. No evidence of target compound degradation existed under either the amended or unamended aerobic conditions; however, the activity observed in some samples under anaerobic conditions suggested transformation of chlorinated compounds and pesticides. Results showed that biodegradation may be inducible under certain conditions, but time lags and efficiencies could be expected to vary considerably. A remedial alternative analysis could not be expected to achieve the degree of accuracy and precision necessary without the data resulting from this study.

  19. New Pt/Alumina model catalysts for STM and in situ XPS studies

    NASA Astrophysics Data System (ADS)

    Nartova, Anna V.; Gharachorlou, Amir; Bukhtiyarov, Andrey V.; Kvon, Ren I.; Bukhtiyarov, Valerii I.

    2017-04-01

    The new Pt/alumina model catalysts for STM and in situ XPS studies based on thin alumina film formed over the conductive substrate are proposed. Procedure of platinum deposition developed for porous alumina was adapted for the model alumina support. The set of Pt/AlOx-film samples with the different mean platinum particle size was prepared. Capabilities of in situ XPS investigations of the proposed catalysts were demonstrated in study of NO decomposition on platinum nanoparticles. It is shown that proposed model catalysts behave similarly to Pt/γ-Al2O3 and provide the new opportunities for the instrumental studies of platinum catalysts due to resolving several issues (charging, heating, screening) that are typical for the investigation of the porous oxide supported catalysts.

  20. Materials testing for in situ stabilization treatability study of INEEL mixed wastes soils

    SciTech Connect

    Heiser, J.; Fuhrmann, M.

    1997-09-01

    This report describes the contaminant-specific materials testing phase of the In Situ Stabilization Comprehensive Environment Response, Compensation, and Liability Act (CERCLA) Treatability Study (TS). The purpose of materials testing is to measure the effectiveness of grouting agents to stabilize Idaho National Engineering and Environmental Laboratory (INEEL) Acid Pit soils and select a grout material for use in the Cold Test Demonstration and Acid Pit Stabilization Treatability Study within the Subsurface Disposal Area (SDA) at the Radioactive Waste Management Complex (RWMC). Test results will assist the selecting a grout material for the follow-on demonstrations described in Test Plan for the Cold Test Demonstration and Acid Pit Stabilization Phases of the In Situ Stabilization Treatability Study at the Radioactive Waste Management Complex.

  1. Demonstration testing and evaluation of in situ soil heating. Treatability study work plan (Revision 2)

    SciTech Connect

    Sresty, G.C.

    1994-12-30

    A Treatability Study planned for the demonstration of the in situ electromagnetic (EM) heating process to remove organic solvents is described in this Work Plan. The treatability study will be conducted by heating subsurface vadose-zone soils in an organic plume adjacent to the Classified Burial Ground K-1070-D located at K-25 Site, Oak Ridge. The test is scheduled to start during the fourth quarter of FY94 and will be completed during the first quarter of FY95. Over the last nine years, a number of Government agencies (EPA, Army, AF, and DOE) and industries sponsored further development and testing of the in situ heating and soil decontamination process for the remediation of soils containing hazardous organic contaminants. In this process the soil is heated in situ using electrical energy. The contaminants are removed from the soil due to enhanced vaporization, steam distillation and stripping. IITRI will demonstrate the EM Process for in situ soil decontamination at K-25 Site under the proposed treatability study. Most of the contaminants of concern are volatile organics which can be removed by heating the soil to a temperature range of 85{degrees} to 95{degrees}C. The efficiency of the treatment will be determined by comparing the concentration of contaminants in soil samples. Samples will be obtained before and after the demonstration for a measurement of the concentration of contaminants of concern. This document is a Treatability Study Work Plan for the demonstration program. The document contains a description of the proposed treatability study, background of the EM heating process, description of the field equipment, and demonstration test design.

  2. A flow-through hydrothermal cell for in situ neutron diffraction studies of phase transformations

    NASA Astrophysics Data System (ADS)

    O'Neill, Brian; Tenailleau, Christophe; Nogthai, Yung; Studer, Andrew; Brugger, Joël; Pring, Allan

    2006-11-01

    A flow-through hydrothermal cell for the in situ neutron diffraction study of crystallisation and phase transitions has been developed. It can be used for kinetic studies on materials that exhibit structural transformations under hydrothermal conditions. It is specifically designed for use on the medium-resolution powder diffractometer (MRPD) at ANSTO, Lucas Heights, Sydney. But it is planned to adapt the design for the Polaris beamline at ISIS and the new high-intensity powder diffractometer (Wombat) at the new Australian reactor Opal. The cell will operate in a flow-through mode over the temperature range from 25-300 °C and up to pressures of 100 bar. The first results of a successful transformation of pentlandite (Fe,Ni) 9S 8 to violarite (Fe,Ni) 3S 4 under mild conditions (pH∼4) at 120 °C and 3 bar using in situ neutron diffraction measurements are presented.

  3. An in situ transmission electron microscope deformation study of the slip transfer mechanisms in metals

    SciTech Connect

    Lee, T.C.; Robertson, I.M.; Birnbaum, H.K. . Dept. of Materials Science and Engineering)

    1990-09-01

    The slip transfer mechanisms across grain boundaries in 310 stainless steel, high-purity aluminum, and a Ni-S alloy have been studied by using the in situ transmission electron microscope (TEM) deformation technique. Several interactions between mobile lattice dislocations and grain boundaries have been observed, including the transfer and generation of dislocations at grain boundaries and the nucleation and propagation of a grain boundary crack. Quantitative condition have been established to correctly predict the slip transfer mechanism.

  4. Automated data extraction from in situ protein-stable isotope probing studies.

    PubMed

    Slysz, Gordon W; Steinke, Laurey; Ward, David M; Klatt, Christian G; Clauss, Therese R W; Purvine, Samuel O; Payne, Samuel H; Anderson, Gordon A; Smith, Richard D; Lipton, Mary S

    2014-03-07

    Protein-stable isotope probing (protein-SIP) has strong potential for revealing key metabolizing taxa in complex microbial communities. While most protein-SIP work to date has been performed under controlled laboratory conditions to allow extensive isotope labeling of the target organism(s), a key application will be in situ studies of microbial communities for short periods of time under natural conditions that result in small degrees of partial labeling. One hurdle restricting large-scale in situ protein-SIP studies is the lack of algorithms and software for automated data processing of the massive data sets resulting from such studies. In response, we developed Stable Isotope Probing Protein Extraction Resources software (SIPPER) and applied it for large-scale extraction and visualization of data from short-term (3 h) protein-SIP experiments performed in situ on phototrophic bacterial mats isolated from Yellowstone National Park. Several metrics incorporated into the software allow it to support exhaustive analysis of the complex composite isotopic envelope observed as a result of low amounts of partial label incorporation. SIPPER also enables the detection of labeled molecular species without the need for any prior identification.

  5. Automated data extraction from in situ protein stable isotope probing studies

    SciTech Connect

    Slysz, Gordon W.; Steinke, Laurey A.; Ward, David M.; Klatt, Christian G.; Clauss, Therese RW; Purvine, Samuel O.; Payne, Samuel H.; Anderson, Gordon A.; Smith, Richard D.; Lipton, Mary S.

    2014-01-27

    Protein stable isotope probing (protein-SIP) has strong potential for revealing key metabolizing taxa in complex microbial communities. While most protein-SIP work to date has been performed under controlled laboratory conditions to allow extensive isotope labeling of the target organism, a key application will be in situ studies of microbial communities under conditions that result in small degrees of partial labeling. One hurdle restricting large scale in situ protein-SIP studies is the lack of algorithms and software for automated data processing of the massive data sets resulting from such studies. In response, we developed Stable Isotope Probing Protein Extraction Resources software (SIPPER) and applied it for large scale extraction and visualization of data from short term (3 h) protein-SIP experiments performed in situ on Yellowstone phototrophic bacterial mats. Several metrics incorporated into the software allow it to support exhaustive analysis of the complex composite isotopic envelope observed as a result of low amounts of partial label incorporation. SIPPER also enables the detection of labeled molecular species without the need for any prior identification.

  6. Studies of a photochromic model system using NMR with ex-situ and in-situ irradiation devices.

    PubMed

    Wolff, Christiane; Kind, Jonas; Schenderlein, Helge; Bartling, Hanna; Feldmeier, Christian; Gschwind, Ruth M; Biesalski, Markus; Thiele, Christina M

    2016-06-01

    The switching behavior of a photochromic model system was investigated in detail via NMR spectroscopy in order to improve understanding of the compound itself and to provide ways to obtain insights into composition trends of a photo switchable (polymeric) material containing spiropyran/merocyanine units. In addition to the classical irradiation performed outside the magnet (ex-situ), a device for irradiation inside the NMR spectrometer (in-situ) was tested. Both setups are introduced, their advantages and disadvantages as well as their limits are described and the setup for future investigations of photochromic materials is suggested. The influence of different sample concentrations, irradiation procedures, and light intensities on the model system was examined as well as the dependence on solvent, temperature, and irradiation wavelengths. Using the recently published LED illumination device, it was even possible to record two-dimensional spectra on this model system with rather short half-life (7 min in DMSO). This way (13) C chemical shifts of the merocyanine form were obtained, which were unknown before. Copyright © 2016 John Wiley & Sons, Ltd.

  7. Demonstration testing and evaluation of in situ soil heating. Treatability study work plan, Revision 1

    SciTech Connect

    Sresty, G.C.

    1994-07-07

    A Treatability Study planned for the demonstration of the in situ electromagnetic (EM) heating process to remove organic solvents is described in this Work Plan. The treatability study will be conducted by heating subsurface vadose-zone soils in an organic plume adjacent to the Classified Burial Ground K-1070-D located at K-25 Site, Oak Ridge. The test is scheduled to start during the fourth quarter of FY94 and will be completed during the first quarter of FY95. The EM heating process for soil decontamination is based on volumetric heating technologies developed during the `70s for the recovery of fuels from shale and tar sands by IIT Research Institute (IITRI) under a co-operative program with the US Department of Energy (DOE). Additional modifications of the technology developed during the mid `80s are currently used for the production of heavy oil and waste treatment. Over the last nine years, a number of Government agencies (EPA, Army, AF, and DOE) and industries sponsored further development and testing of the in situ heating and soil decontamination process for the remediation of soils containing hazardous organic contaminants. In this process the soil is heated in situ using electrical energy. The contaminants are removed from the soil due to enhanced vaporization, steam distillation and stripping. IITRI will demonstrate the EM Process for in situ soil decontamination at K-25 Site under the proposed treatability study. Most of the contaminants of concern are volatile organics which can be removed by heating the soil to a temperature range of 85 to 95 C. The efficiency of the treatment will be determined by comparing the concentration of contaminants in soil samples. Samples will be obtained before and after the demonstration for a measurement of the concentration of contaminants of concern.

  8. Reaction of Formic Acid over Amorphous Manganese Oxide Catalytic Systems: An In Situ Study

    SciTech Connect

    J Durand; S Senanayake; S Suib; D Mullins

    2011-12-31

    The interaction of formic acid with amorphous manganese oxide (AMO) is investigated using in situ photoelectron and infrared spectroscopy techniques. Soft X-ray photoelectron spectroscopy (sXPS) and in situ FTIR illustrate two possible modes of formate bound species at the AMO surface. Two peaks in the IR region from 1340-1390 cm{sup -1} are indicative of formate species bound to the surface in a bidentate configuration. However, a 224 cm{sup -1} band gap between v{sub s}OCO and v{sub as}OCO suggests formate is bound in a bridging configuration. Temperature-programmed desorption studies confirm the formate bound species desorbs as carbon dioxide from the surface at multiple binding sites. At temperatures above 700 K, the presence of K{sup +} {hor_ellipsis} OC complex suggests the bound species interacts at vacant sites related to framework oxygen and cation mobility.

  9. Reaction of Formic Acid over Amorphous Manganese Oxide Catalytic Systems: An In Situ Study

    SciTech Connect

    Durand, Jason; Senanayake, Sanjaya D; Mullins, David R; Suib, Steven

    2010-01-01

    The interaction of formic acid with amorphous manganese oxide (AMO) is investigated using in situ photoelectron and infrared spectroscopy techniques. Soft X-ray photoelectron spectroscopy (sXPS) and in situ FTIR illustrate two possible modes of formate bound species at the AMO surface. Two peaks in the IR region from 1340-1390 cm{sup -1} are indicative of formate species bound to the surface in a bidentate configuration. However, a 224 cm{sup -1} band gap between v{sub s}OCO and v{sub as}OCO suggests formate is bound in a bridging configuration. Temperature-programmed desorption studies confirm the formate bound species desorbs as carbon dioxide from the surface at multiple binding sites. At temperatures above 700 K, the presence of K{sup +} {hor_ellipsis} OC complex suggests the bound species interacts at vacant sites related to framework oxygen and cation mobility.

  10. A case study of in situ oil contamination in a mangrove swamp (Rio De Janeiro, Brazil).

    PubMed

    Brito, Elcia M S; Duran, Robert; Guyoneaud, Rémy; Goñi-Urriza, Marisol; García de Oteyza, T; Crapez, Miriam A C; Aleluia, Irene; Wasserman, Julio C A

    2009-08-01

    Mangroves are sensitive ecosystems of prominent ecological value that lamentably have lost much of their areas across the world. The vulnerability of mangroves grown in proximity to cities requires the development of new technologies for the remediation of acute oil spills and chronic contaminations. Studies on oil remediation are usually performed with in vitro microcosms whereas in situ experiments are rare. The aim of this work was to evaluate oil degradation on mangrove ecosystems using in situ microcosms seeded with an indigenous hydrocarbonoclastic bacterial consortium (HBC). Although the potential degradation of oil through HBC has been reported, their seeding directly on the sediment did not stimulate oil degradation during the experimental period. This is probably due to the availability of carbon sources that are easier to degrade than petroleum hydrocarbons. Our results emphasize the fragility of mangrove ecosystems during accidental oil spills and also the need for more efficient technologies for their remediation.

  11. Studies on the intercalation of naproxen into layered double hydroxide and its thermal decomposition by in situ FT-IR and in situ HT-XRD

    NASA Astrophysics Data System (ADS)

    Wei, Min; Shi, Shuxian; Wang, Ji; Li, Yong; Duan, Xue

    2004-07-01

    Layered double hydroxides, novel anionic clay, meet the first requirement as inorganic matrices for encapsulating functional drugs or biomolecules with negative charge in aqueous media. In this study, naproxen has been intercalated into Mg-Al layered double hydroxide by the methods of ion exchange. The structure and composition of the intercalated material have been studied by X-ray diffraction (XRD), UV-vis spectroscopy and inductively coupled plasma emission spectroscopy. A schematic model has been proposed. Furthermore, in situ Fourier transform infrared spectroscopy, in situ high-temperature XRD, and thermogravimetry (TG) have been used to characterize the thermal decomposition of the hybrid material. It has been found that the thermal stability of the intercalated naproxen is significantly enhanced compared with the pure form before intercalation, which suggests that this drug-inorganic layered material may have prospective application as the basis of a novel drug delivery system.

  12. Nitric oxide synthases: structure, function and inhibition.

    PubMed Central

    Alderton, W K; Cooper, C E; Knowles, R G

    2001-01-01

    This review concentrates on advances in nitric oxide synthase (NOS) structure, function and inhibition made in the last seven years, during which time substantial advances have been made in our understanding of this enzyme family. There is now information on the enzyme structure at all levels from primary (amino acid sequence) to quaternary (dimerization, association with other proteins) structure. The crystal structures of the oxygenase domains of inducible NOS (iNOS) and vascular endothelial NOS (eNOS) allow us to interpret other information in the context of this important part of the enzyme, with its binding sites for iron protoporphyrin IX (haem), biopterin, L-arginine, and the many inhibitors which interact with them. The exact nature of the NOS reaction, its mechanism and its products continue to be sources of controversy. The role of the biopterin cofactor is now becoming clearer, with emerging data implicating one-electron redox cycling as well as the multiple allosteric effects on enzyme activity. Regulation of the NOSs has been described at all levels from gene transcription to covalent modification and allosteric regulation of the enzyme itself. A wide range of NOS inhibitors have been discussed, interacting with the enzyme in diverse ways in terms of site and mechanism of inhibition, time-dependence and selectivity for individual isoforms, although there are many pitfalls and misunderstandings of these aspects. Highly selective inhibitors of iNOS versus eNOS and neuronal NOS have been identified and some of these have potential in the treatment of a range of inflammatory and other conditions in which iNOS has been implicated. PMID:11463332

  13. In situ studies of nanoscale electromechanical behavior of nacre under flexural stresses using band excitation PFM.

    PubMed

    Li, Tao; Chen, Lei; Zeng, Kaiyang

    2013-04-01

    In this paper, we have studied the electromechanical coupling behaviors of nacre under non-destructive flexural stresses. Band excitation piezoresponse force microscopy is used as the primary tool to characterize the piezoelectric properties of nacre. This method can differentiate various constituents in nacre at the nanoscale and track their in situ responses under tensile and compressive stresses. The local ferroelectric hysteresis behaviors of nacre are also studied. Based on the hysteresis loops observed under different stress states, various phenomena, including the stress-induced internal field and energy loss, are revealed in this study.

  14. In-situ bioventing: Two US EPA and Air Force sponsored field studies

    SciTech Connect

    Sayles, G.D.; Hinchee, R.E.; Brenner, R.C.; Vogel, C.M.; Miller, R.N.

    1992-01-01

    Bioventing is the process of delivering oxygen by forced air movement through organically contaminated unsaturated soils in order to stimulate in situ biodegradation in an otherwise oxygen-limited environment. The paper is a report on progress of two ongoing bioventing field studies involving JP-4 jet fuel contamination. The first investigation, at Eielson AFB near Fairbanks, Alaska, is a study of bioventing in shallow soils and cold climates in conjunction with an evaluation of soil warming techniques. The second study, at Hill AFB near Salt Lake City, Utah, is examining bioventing of large volumes of soil and determining biodegradation and volatilization rates as a function of air injection rate.

  15. In situ SEM Study of Lithium Intercalation in individual V2O5 Nanowires

    DOE PAGES

    Strelcov, Evgheni; Cothren, Joshua E.; Leonard, Donovan N.; ...

    2015-01-08

    Progress in rational engineering of Li-ion batteries requires better understanding of the electrochemical processes and accompanying transformations in the electrode materials on multiple length scales. In spite of recent progress in utilizing transmission electron microscopy (TEM) to analyze these materials, in situ scanning electron microscopy (SEM) was mostly overlooked as a powerful tool that allows probing these phenomena on the nano and mesoscale. In this paper, we report on in situ SEM study of lithiation in a V2O5-based single-nanobelt battery with ionic liquid electrolyte. Coupled with cyclic voltammetry measurements, in situ SEM revealed the peculiarities of subsurface intercalation, formation ofmore » solid-electrolyte interface (SEI) and electromigration of liquid. We observed that single-crystalline vanadia nanobelts do not undergo large-scale amorphization or fracture during electrochemical cycling, but rather transform topochemically with only a slight shape distortion. Lastly, the SEI layer seems to have significant influence on the lithium ion diffusion and overall capacity of the single-nanobelt battery.« less

  16. Corrosion of an alloy studied in situ with synchrotron x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Renner, Frank; Lee, Tien-Lin; Kolb, Dieter M.; Stierle, Andreas; Dosch, Helmut; Zegenhagen, Jorg

    2004-03-01

    Corrosion processes are mostly electrochemical in nature. For the basic understanding of corrosion and similar technical processes, in-situ structural methods capable of atomic resolution, such as scanning probe microscopy or hard X-ray techniques are necessary. We used in-situ X-ray diffraction and in addition ex-situ AFM, to study Cu_3Au(111) single crystal surfaces in 0.1M H_2SO4 electrolyte as a function of electrode potential in the sub-critical regime. This binary metal alloys serves as model systems for more complicated technically utilized metal alloys. During the initial electrochemical corrosion, Cu atoms are dissolved and a passivating layer is formed. The experiments show the formation of an epitaxial and highly strained ultra-thin Cu_xAu_1-x(111) phase on the surface at a potential where Cu dissolution starts. At higher potentials, thicker epitaxial Au islands are growing on the surface. AFM images reveal a surface, densely packed with Au islands of a homogeneous size-distribution. On a prolonged timescale, a percolating, porous morphology of the surface evolves by ripening, even at an electrode potential well below the critical potential.

  17. The applications of in situ electron energy loss spectroscopy to the study of electron beam nanofabrication.

    PubMed

    Chen, Shiahn J; Howitt, David G; Gierhart, Brian C; Smith, Rosemary L; Collins, Scott D

    2009-06-01

    An in situ electron energy loss spectroscopy (EELS) technique has been developed to investigate the dynamic processes associated with electron-beam nanofabrication on thin membranes. In this article, practical applications germane to e-beam nanofabrication are illustrated with a case study of the drilling of nanometer-sized pores in silicon nitride membranes. This technique involves successive acquisitions of the plasmon-loss and the core-level ionization-loss spectra in real time, both of which provide the information regarding the hole-drilling kinetics, including two respective rates for total mass loss, individual nitrogen and silicon element depletion, and the change of the atomic bonding environment. In addition, the in situ EELS also provides an alternative method for endpoint detection with a potentially higher time resolution than by imaging. On the basis of the time evolution of in situ EELS spectra, a qualitative working model combining knock-on sputtering, irradiation-induced mass transport, and phase separation can be proposed.

  18. In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

    DOE PAGES

    Chen, Youxing; Li, Nan; Bufford, Daniel Charles; ...

    2016-04-09

    By providing active defect sinks that capture and annihilate radiation induced defect clusters immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In our study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electronmore » microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Moreover, in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.« less

  19. In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

    SciTech Connect

    Chen, Youxing; Li, Nan; Bufford, Daniel Charles; Li, Jin; Hattar, Khalid Mikhiel; Wang, Haiyan; Zhang, Xinghang

    2016-04-09

    By providing active defect sinks that capture and annihilate radiation induced defect clusters immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In our study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electron microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Moreover, in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.

  20. In situ studies on ferroelectric BaTiO3 interface

    NASA Astrophysics Data System (ADS)

    Shin, Junsoo; Braun Nascimento, Von; Plummer, Ward; Zhang, Jiandi; Borisevich, Albina; Meunier, Vincent; Kalinin, Sergei; Baddorf, Arthur

    2012-02-01

    Ferroelectric phase stability in ferroelectric films is critically dependent on the surface and interface phenomena, especially governed by electrostatic depolarization energy. Predictions for the minimum critical film thickness for ferroelectricity have continuously decreased down to few unit cells. We have examined surface/interface atomic structures of ultrathin BaTiO3 (BTO) films grown on conductive SrRuO3 (SRO) and Nb-doped SrTiO3. The surface structure of BTO/SRO was refined using in-situ Low Energy Electron Diffraction (LEED) I-V, resulting to observation of polar distortion in ultrathin (>= 4 ML) BTO films. The in-situ Scanning Tunneling Microscopy (STM) has been performed prior and after BTO deposition on SRO. However, the unusual 2x2 reconstruction is observed for 1-2 ML BTO films and bare SRO by STM. The surface reconstruction of SRO bottom electrode is shown to affect the interface of films deposited subsequently which could be reflected in ultrathin film properties. The in-situ LEED I-V structural studies on 1-2 ML BTO interface have been performed without SRO layer, which kept ultrathin BTO films from the preclusion of reconstructed SRO films.

  1. An in situ approach to study trace element partitioning in the laser heated diamond anvil cell

    SciTech Connect

    Petitgirard, S.; Mezouar, M.; Borchert, M.; Appel, K.; Liermann, H.-P.; Andrault, D.

    2012-01-15

    Data on partitioning behavior of elements between different phases at in situ conditions are crucial for the understanding of element mobility especially for geochemical studies. Here, we present results of in situ partitioning of trace elements (Zr, Pd, and Ru) between silicate and iron melts, up to 50 GPa and 4200 K, using a modified laser heated diamond anvil cell (DAC). This new experimental set up allows simultaneous collection of x-ray fluorescence (XRF) and x-ray diffraction (XRD) data as a function of time using the high pressure beamline ID27 (ESRF, France). The technique enables the simultaneous detection of sample melting based to the appearance of diffuse scattering in the XRD pattern, characteristic of the structure factor of liquids, and measurements of elemental partitioning of the sample using XRF, before, during and after laser heating in the DAC. We were able to detect elements concentrations as low as a few ppm level (2-5 ppm) on standard solutions. In situ measurements are complimented by mapping of the chemical partitions of the trace elements after laser heating on the quenched samples to constrain the partitioning data. Our first results indicate a strong partitioning of Pd and Ru into the metallic phase, while Zr remains clearly incompatible with iron. This novel approach extends the pressure and temperature range of partitioning experiments derived from quenched samples from the large volume presses and could bring new insight to the early history of Earth.

  2. The ratio of the beauty structure functions Rb=FLb/F2b at low x

    NASA Astrophysics Data System (ADS)

    Boroun, G. R.

    2014-07-01

    We study the structure functions Fkb(x,Q2) (k=2,L) and the reduced cross section σrb(x,Q2) for small values of Bjorken's x variable with respect to the hard (Lipatov) pomeron for the gluon distribution and provide a compact formula for the ratio Rb that is useful to extract the beauty structure function from the beauty reduced cross section, in particular at DESY HERA. Also we show that the effects of the nonlinear corrections to the gluon distribution tame the behavior of the beauty structure function and the beauty reduced cross section at low x.

  3. Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons

    SciTech Connect

    Bodek, Arie

    2016-08-01

    We present preliminary results on an experimental study of the nuclear modification of the longitudinal ($\\sigma_L$) and transverse ($\\sigma_T$) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= $\\sigma_L / \\sigma_T$ for nuclei ($R_A$) and for deuterium ($R_D$) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, $R_A< R_D$.

  4. In-situ x-ray absorption study of copper films in ground watersolutions

    SciTech Connect

    Kvashnina, K.O.; Butorin, S.M.; Modin, A.; Soroka, I.; Marcellini, M.; Nordgren, J.; Guo, J.-H.; Werme, L.

    2007-10-29

    This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl{sup -} and HCO{sub 3}{sup -} in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM HCO{sub 3}{sup -} prevented or slowed down the corrosion processes.

  5. In situ hybridization study of CYP2D mRNA in the common marmoset brain

    PubMed Central

    Shimamoto, Yoshinori; Niimi, Kimie; Kitamura, Hiroshi; Tsubakishita, Sae; Takahashi, Eiki

    2016-01-01

    The common marmoset is a non-human primate that has increasingly employed in the biomedical research including the fields of neuroscience and behavioral studies. Cytochrome P450 (CYP) 2D has been speculated to be involved in psycho-neurologic actions in the human brain. In the present study, to clarify the role of CYP2D in the marmoset brain, we investigated the expression patterns of CYP2D mRNA in the brain using in situ hybridization (ISH). In addition, to identify the gene location of CYP2D19, a well-studied CYP2D isoform in the common marmoset, a fluorescence in situ hybridization (FISH) study was performed. Consistent with findings for the human brain, CYP2D mRNA was localized in the neuronal cells of different brain regions; e.g., the cerebral cortex, hippocampus, substantia nigra, and cerebellum. FISH analysis showed that the CYP2D19 gene was located on chromosome 1q, which is homologous to human chromosome 22 on which the CYP2D6 gene exists. These results suggest that CYP2D in the marmoset brain may play the same role as human CYP2D6 in terms of brain actions, and that the CYP2D19 gene is conserved in a syntenic manner. Taken together, these findings suggest that the common marmoset is a useful model for studying psychiatric disorders related to CYP2D dysfunction in the brain. PMID:27356856

  6. Electro-deposition of Cu studied with in situ electrochemical scanning transmission x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Hitchcock, A. P.; Qin, Z.; Rosendahl, S. M.; Lee, V.; Reynolds, M.; Hosseinkhannazer, H.

    2016-01-01

    Soft X-ray scanning transmission X-ray microscopy (STXM) was used to investigate Cu deposition onto, and stripping from a Au surface. Cu 2p spectromicroscopy was used to analyze initial and final states (ex situ processing) and follow the processes in situ. The in situ experiments were carried out using a static electrochemical cell with an electrolyte layer thickness of ˜1 μm. A new apparatus for in situ electrochemical STXM is described.

  7. Combined in-situ dilatometer and contact angle studies of interfacial reaction kinetics in brazing.

    SciTech Connect

    Dave, V. R.; Javernick, D. A.; Thoma, D. J.; Cola, M. J.; Hollis, K. J.; Smith, F. M.; Dauelsberg, L. B.

    2001-01-01

    Multi-component dissimilar material braze joints as shown in Figure 1 consisting of dissimilar base materials, filler materials and wetting agents are of tantamount importance in a wide variely of applications. This work combines dilatometry and contact angle measurements to characterize in-situ the multiple interfacial reaction pathways that occur in such systems. Whereas both of these methods are commonly used tools in metallurgical investigation, their combined use within the context of brazing studies is new and offers considerable additional insight. Applications are discussed to joints made between Beryllium and Monel with TiH{sub 2} as the wetting agent and Cu-28%Ag as the filler material.

  8. XAFS characterization of industrial catalysts: in situ study of phase transformation of nickel sulfide

    NASA Astrophysics Data System (ADS)

    Wang, J.; Jia, Z.; Wang, Q.; Zhao, S.; Xu, Z.; Yang, W.; Frenkel, A. I.

    2016-05-01

    The online sulfiding process for nickel-contained catalyst often ends up with a nickel sulfide mixture in refinery plant. To elucidate the local environment of nickel and its corresponding sulfur species, a model catalyst (nickel sulfide) and model thermal process were employed to explore the possibilities for characterization of real catalysts in industrial conditions. The present investigation shows effectiveness of in situ XANES and EXAFS measurements for studying the phase stability and phase composition in these systems, which could be used to simulate real sulfiding process in industrial reactions, such as hydrodesulfurizations of oil.

  9. In situ Hall-effect system for real-time electron-irradiation studies

    SciTech Connect

    Ziebro, B.S.; Look, D.C.; Hemsky, J.W.; Rice, W. )

    1990-01-01

    A unique system capable of taking {ital in} {ital situ} Hall-effect measurements during electron irradiation has been developed. The key element is a small, powerful rare-earth magnet. Measurements can be taken while the electron beam is on, resulting in a considerable time savings and eliminating problems associated with mounting and demounting the sample. High resolution electron concentration and mobility versus fluence data are quickly and easily obtained, making possible detailed defect production rate studies as functions of energy and flux.

  10. Structure-function relationship of monocot mannose-binding lectins.

    PubMed Central

    Barre, A; Van Damme, E J; Peumans, W J; Rougé, P

    1996-01-01

    The monocot mannose-binding lectins are an extended superfamily of structurally and evolutionarily related proteins, which until now have been isolated from species of the Amaryllidaceae, Alliaceae, Araceae, Orchidaceae, and Liliaceae. To explain the obvious differences in biological activities, the structure-function relationships of the monocot mannose-binding lectins were studied by a combination of glycan-binding studies and molecular modeling using the deduced amino acid sequences of the currently known lectins. Molecular modeling indicated that the number of active mannose-binding sites per monomer varies between three and zero. Since the number of binding sites is fairly well correlated with the binding activity measured by surface plasmon resonance, and is also in good agreement with the results of previous studies of the biological activities of the mannose-binding lectins, molecular modeling is of great value for predicting which lectins are best suited for a particular application. PMID:8972598

  11. In Situ Synchrotron X-ray Study of Ultrasound Cavitation and Its Effect on Solidification Microstructures

    NASA Astrophysics Data System (ADS)

    Mi, Jiawei; Tan, Dongyue; Lee, Tung Lik

    2015-08-01

    Considerable progress has been made in studying the mechanism and effectiveness of using ultrasound waves to manipulate the solidification microstructures of metallic alloys. However, uncertainties remain in both the underlying physics of how microstructures evolve under ultrasonic waves, and the best technological approach to control the final microstructures and properties. We used the ultrafast synchrotron X-ray phase contrast imaging facility housed at the Advanced Photon Source, Argonne National Laboratory, US to study in situ the highly transient and dynamic interactions between the liquid metal and ultrasonic waves/bubbles. The dynamics of ultrasonic bubbles in liquid metal and their interactions with the solidifying phases in a transparent alloy were captured in situ. The experiments were complemented by the simulations of the acoustic pressure field, the pulsing of the bubbles, and the associated forces acting onto the solidifying dendrites. The study provides more quantitative understanding on how ultrasonic waves/bubbles influence the growth of dendritic grains and promote the grain multiplication effect for grain refinement.

  12. Applications of Isotopes in Advancing Structural & Functional Heparanomics

    PubMed Central

    Tran, Vy M.; Nu Nguyen, Thao Kim; Raman, Karthik; Kuberan, Balagurunathan

    2011-01-01

    Heparanomics is the study of all the biologically active oligosaccharide domain structures in the entire heparanome and the nature of interactions among these domains and their protein ligands. Structural elucidation of heparan sulfate and heparin oligosaccharides is a major obstacle in advancing structure-function relationships and the study of heparanomics. There are several factors that exacerbate challenges involved in the structural elucidation of heparin and heparan sulfate. Therefore, there is a great interest in developing novel strategies and analytical tools to overcome the barriers in decoding the enigmatic heparanome. This review article focuses on the applications of isotopes, both radioisotopes and stable isotopes, in the structural elucidation of the complex heparanome at the disaccharide or oligosaccharide level using liquid chromatography, nuclear magnetic resonance spectroscopy and mass spectrometry. This review article also outlines the utility of isotopes in determining the substrate specificity of biosynthetic enzymes that eventually dictate the emergence of biologically active oligosaccharides. PMID:20838780

  13. In Situ X-ray Diffraction Studies of Cathode Materials in Lithium Batteries

    SciTech Connect

    Yang, X. Q.; Sun, X.; McBreen, J.; Mukerjee, S.; Gao, Yuan; Yakovleva, M. V.; Xing, X. K.; Daroux, M. L.

    1998-11-01

    There is an increasing interest in lithiated transition metal oxides because of their use as cathodes in lithium batteries. LiCoO{sub 2}, LiNiO{sub 2} and LiMn{sub 2}O{sub 4} are the three most widely used and studied materials, At present, although it is relative expensive and toxic, LiCoO{sub 2} is the material of choice in commercial lithium ion batteries because of its ease of manufacture, better thermal stability and cycle life. However, the potential use of lithium ion batteries with larger capacity for power tools and electric vehicles in the future will demand new cathode materials with higher energy density, lower cost and better thermal stability. LiNiO{sub 2} is isostructural with LiCoO{sub 2}. It offers lower cost and high energy density than LiCoO{sub 2}. However, it has much poorer thermal stability than LiCoO{sub 2}, in the charged (delithiated) state. Co, Al, and other elements have been used to partially replace Ni in LiNiO{sub 2} system in order to increase the thermal stability. LiMn{sub 2}O{sub 4} has the highest thermal stability and lowest cost and toxicity. However, the low energy density and poor cycle life at elevated temperature are the major obstacles for this material. In order to develop safer, cheaper, and better performance cathode materials, the in-depth understanding of the relationships between the thermal stability and structure, performance and structure are very important. The performance here includes energy density and cycle life of the cathode materials. X-ray diffraction (XRD) is one of the most powerful tools to study these relationships. The pioneer ex situ XRD work on cathode materials for lithium batteries was done by Ohzuku. His XRD studies on LiMn{sub 2}O{sub 4}, LiCoO{sub 2}, LiNiO{sub 2}, LiNi{sub 0.5}Co{sub 0.5}O{sub 2}, and LiAl{sub x}Ni{sub 1-x}O{sub 2} cathodes at different states of charge have provided important guidelines for the development of these new materials. However, the kinetic nature of the battery

  14. IN SITU STUDIES OF CORROSION USING X-RAY ABSORPTION NEAR SPECTROSCOPY (XANES)

    SciTech Connect

    ISAACS, H.S.; SCHMUKI, P.; VIRTANEN, S.

    2001-03-25

    Applications of x-ray absorption near-edge spectroscopy (XANES) and the design of cells for in situ corrosion studies are reviewed. Passive films studies require very thin metal or alloy layers be used having a thickness of the order of the films formed because of penetration of the x-ray beam into the metal substrate. The depth of penetration in water also limits the thickness of solutions that can be used because of water reduces the x-ray intensity. Solution thickness must also be limited in studies of conversion layer formation studies because the masking of the Cr in solution. Illustrative examples are taken from the anodic behavior of Al-Cr alloys, the growth of passive films on Fe and stainless steels, and the formation of chromate conversion layers on Al.

  15. In situ microcalorimetry study of ZnFe2O4 nanoparticle formation under solvothermal conditions.

    PubMed

    Liu, Jun; Nan, Zhaodong; Gao, Shengli

    2015-10-21

    Solvothermal methods have been widely used to synthesize different kinds of materials. However, only little is known about how precursor solutions react to form solid precipitates via this method. In the present study, in situ microcalorimetry is first used to investigate the formation mechanism under solvothermal conditions, where ZnFe2O4 synthesized using a solvothermal method was selected as the model sample. Some novel results are obtained, such as with the experimental temperature increase, (1) the homogeneous solution transforms to a gel containing amorphous Fe2(C2H4O2)3 and ZnC2H4O2, and NaNO3 crystals; (2) the gel dissolves; (3) α-(Fe,Zn)OOH and α-Fe2O3 are synthesized; (4) the α-(Fe,Zn)OOH transforms to α-Fe2O3; (5) Fe(2+) is formed at about 159 °C, which acts as a catalyst for the formation of Fe3O4; (6) the Fe3O4 crystals are synthesized at about 200 °C; (7) the Fe3O4 is transformed to the ZnFe2O4 with the help of NO3(-), and the reaction was kept at 200 °C for about 20 h. This study shows a facile in situ method for the investigation of reaction processes of solvothermal methods.

  16. In situ, simultaneous thermal imaging and infrared molecular emission studies of solid oxide fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Kirtley, J. D.; Qadri, S. N.; Steinhurst, D. A.; Owrutsky, J. C.

    2016-12-01

    Various in situ probes of solid oxide fuel cells (SOFCs) have advanced recently to provide detailed, real time data regarding materials and chemical processes that relate to device performance and degradation. These techniques offer insights into complex fuel chemistry at the anode in particular, especially in the context of model predictions. However, cell-to-cell variations can hinder mechanistic interpretations of measurements from separate, independent techniques. The present study describes an in situ technique that for the first time simultaneously measures surface temperature changes using near infrared thermal imaging and gas species using Fourier-transform infrared emission spectra at the anodes of operating SOFCs. Electrolyte-supported SOFCs with Ni-based anodes are operated at 700 °C with internal, dry-reformed methane at 75% maximum current and at open circuit voltage (OCV) while electrochemical and optical measurements are collected. At OCV, more cooling is observed coincident with more CO reforming products. Under load, CO decreases while the anode cools less, especially near the current collectors. The extent of cooling is more sensitive to polarization for electrolyte-supported cells because their anodes are thinner relative to anode-supported cells. This study exemplifies how this duplex technique can be a useful probe of electrochemical processes in SOFCs.

  17. Studies of ferroelectric heterostructure thin films and interfaces via in situ analytical techniques.

    SciTech Connect

    Auciello, O.; Dhote, A.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A.; Krauss, A. R.; Mueller, A. H.; Ramesh, R.

    1999-08-30

    The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMs) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and interface processes, which play critical roles in film microstructure and properties. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed.

  18. In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental study.

    PubMed

    Xie, Xianjun; Wang, Yanxin; Pi, Kunfu; Liu, Chongxuan; Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu

    2015-09-15

    In situ arsenic removal from groundwater by an aquifer iron coating method has great potential to be a cost effective and simple groundwater remediation technology, especially in rural and remote areas where groundwater is used as the main water source for drinking. The in situ arsenic removal technology was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions. The effectiveness was then evaluated in an actual high-arsenic groundwater environment. The arsenic removal mechanism by the coated iron oxide/hydroxide was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, electron probe microanalysis, and Fourier transformation infrared spectroscopy. Aquifer iron coating method was developed via a 4-step alternating injection of oxidant, iron salt and oxygen-free water. A continuous injection of 5.0 mmol/L FeSO4 and 2.5 mmol/L NaClO for 96 h can form a uniform goethite coating on the surface of quartz sand without causing clogging. At a flow rate of 7.2 mL/min of the injection reagents, arsenic (as Na2HAsO4) and tracer fluorescein sodium to pass through the iron-coated quartz sand column were approximately at 126 and 7 column pore volumes, respectively. The retardation factor of arsenic was 23.0, and the adsorption capacity was 0.11 mol As per mol Fe. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As(V) and Fe(II) reagents. Arsenic fixation resulted from a process of adsorption/co-precipitation with fine goethite particles by way of bidentate binuclear complexes. Therefore, the study results indicate that the high arsenic removal efficiency of the in situ aquifer iron coating technology likely resulted from the expanded specific surface area of the small goethite particles, which enhanced arsenic sorption capability and/or from co-precipitation of arsenic on the surface of goethite particles.

  19. Moments of Spin Structure Functions: Sum Rules and Polarizabilities

    SciTech Connect

    Jian-Ping Chen

    2010-10-01

    Nucleon structure study is one of the most important research areas in modern physics and has challenged us for decades. Spin has played an essential role and often brought surprises and puzzles to the investigation of the nucleon structure and the strong interaction. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture in the strong region of the interaction and of the transition region from the strong to the asymptotic-free region. Insight for some aspects of the theory for the strong interaction, Quantum Chromodynamics (QCD), is gained by exploring lower moments of spin structure functions and their corresponding sum rules (i.e. the Bjorken, Burkhardt-Cottingham, Gerasimov-Drell-Hearn (GDH), and the generalized GDH). These moments are expressed in terms of an operator-product expansion using quark and gluon degrees of freedom at moderately large momentum transfers.

  20. In situ nanoindentation study on plasticity and work hardening in aluminium with incoherent twin boundaries

    NASA Astrophysics Data System (ADS)

    Bufford, D.; Liu, Y.; Wang, J.; Wang, H.; Zhang, X.

    2014-09-01

    Nanotwinned metals have been the focus of intense research recently, as twin boundaries may greatly enhance mechanical strength, while maintaining good ductility, electrical conductivity and thermal stability. Most prior studies have focused on low stacking-fault energy nanotwinned metals with coherent twin boundaries. In contrast, the plasticity of twinned high stacking-fault energy metals, such as aluminium with incoherent twin boundaries, has not been investigated. Here we report high work hardening capacity and plasticity in highly twinned aluminium containing abundant Σ3{112} incoherent twin boundaries based on in situ nanoindentation studies in a transmission electron microscope and corresponding molecular dynamics simulations. The simulations also reveal drastic differences in deformation mechanisms between nanotwinned copper and twinned aluminium ascribed to stacking-fault energy controlled dislocation-incoherent twin boundary interactions. This study provides new insight into incoherent twin boundary-dominated plasticity in high stacking-fault energy twinned metals.

  1. In situ nanoindentation study on plasticity and work hardening in aluminium with incoherent twin boundaries.

    PubMed

    Bufford, D; Liu, Y; Wang, J; Wang, H; Zhang, X

    2014-09-10

    Nanotwinned metals have been the focus of intense research recently, as twin boundaries may greatly enhance mechanical strength, while maintaining good ductility, electrical conductivity and thermal stability. Most prior studies have focused on low stacking-fault energy nanotwinned metals with coherent twin boundaries. In contrast, the plasticity of twinned high stacking-fault energy metals, such as aluminium with incoherent twin boundaries, has not been investigated. Here we report high work hardening capacity and plasticity in highly twinned aluminium containing abundant Σ3{112} incoherent twin boundaries based on in situ nanoindentation studies in a transmission electron microscope and corresponding molecular dynamics simulations. The simulations also reveal drastic differences in deformation mechanisms between nanotwinned copper and twinned aluminium ascribed to stacking-fault energy controlled dislocation-incoherent twin boundary interactions. This study provides new insight into incoherent twin boundary-dominated plasticity in high stacking-fault energy twinned metals.

  2. Human Microtumors Generated in 3D: Novel Tools for Integrated In Situ Studies of Cancer Immunotherapies.

    PubMed

    Hambach, Lothar; Buser, Andreas; Vermeij, Marcel; Pouw, Nadine; van der Kwast, Theo; Goulmy, Els

    2016-01-01

    Cellular immunotherapy targeting human tumor antigens is a promising strategy to treat solid tumors. Yet clinical results of cellular immunotherapy are disappointing. Moreover, the currently available in vitro human tumor models are not designed to study the optimization of T-cell therapies of solid tumors. Here, we describe a novel assay for multiparametric in situ analysis of therapeutic effects on individual human three-dimensional (3D) tumors. In this assay, tumors of several millimeter diameter are generated from human cancer cell lines of different tumor entities in a collagen type I microenvironment. A newly developed approach for efficient morphological analysis reveals that these in vitro tumors resemble many characteristics of the corresponding clinical cancers such as histological features, immunohistochemical staining patterns, distinct tumor growth compartments and heterogeneous protein expression. To assess the response to therapy with tumor antigen specific T-cells, standardized protocols are described to determine T-cell infiltration and tumor destruction by monitoring soluble factors and tumor growth. Human tumors engineered in 3D collagen scaffolds are excellent in vitro surrogates for avascular tumor stages allowing integrated analyses of the antitumor efficacy of cancer specific immunotherapy in situ.

  3. Chemometric Study of the Ex Situ Underground Coal Gasification Wastewater Experimental Data.

    PubMed

    Smoliński, Adam; Stańczyk, Krzysztof; Kapusta, Krzysztof; Howaniec, Natalia

    2012-11-01

    The main goal of the study was the analysis of the parameters of wastewater generated during the ex situ underground coal gasification (UCG) experiments on lignite from Belchatow, and hard coal from Ziemowit and Bobrek coal mines, simulated in the ex situ reactor. The UCG wastewater may pose a potential threat to the groundwater since it contains high concentrations of inorganic (i.e., ammonia nitrogen, nitrites, chlorides, free and bound cyanides, sulfates and trace elements: As, B, Cr, Zn, Al, Cd, Co, Mn, Cu, Mo, Ni, Pb, Hg, Se, Ti, Fe) and organic (i.e., phenolics, benzene and their alkyl derivatives, and polycyclic aromatic hydrocarbons) contaminants. The principal component analysis and hierarchical clustering analysis enabled to effectively explore the similarities and dissimilarities between the samples generated in lignite and hard coal oxygen gasification process in terms of the amounts and concentrations of particular components. The total amount of wastewater produced in lignite gasification process was higher than the amount generated in hard coal gasification experiments. The lignite gasification wastewater was also characterized by the highest contents of acenaphthene, phenanthrene, anthracene, fluoranthene, and pyrene, whereas hard coal gasification wastewater was characterized by relatively higher concentrations of nitrites, As, Cr, Cu, benzene, toluene, xylene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene.

  4. In Situ Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Lithium-Oxygen Redox Reactions

    NASA Astrophysics Data System (ADS)

    Lu, Yi-Chun; Crumlin, Ethan J.; Veith, Gabriel M.; Harding, Jonathon R.; Mutoro, Eva; Baggetto, Loïc; Dudney, Nancy J.; Liu, Zhi; Shao-Horn, Yang

    2012-10-01

    The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li4+xTi5O12/LiPON/LixV2O5 cell and examine in situ the chemistry of Li-O2 reaction products on LixV2O5 as a function of applied voltage under ultra high vacuum (UHV) and at 500 mtorr of oxygen pressure using ambient pressure X-ray photoelectron spectroscopy (APXPS). Under UHV, lithium intercalated into LixV2O5 while molecular oxygen was reduced to form lithium peroxide on LixV2O5 in the presence of oxygen upon discharge. Interestingly, the oxidation of Li2O2 began at much lower overpotentials (~240 mV) than the charge overpotentials of conventional Li-O2 cells with aprotic electrolytes (~1000 mV). Our study provides the first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O2 chemistry.

  5. Prioritising in situ conservation of crop resources: a case study of African cowpea (Vigna unguiculata).

    PubMed

    Moray, C; Game, E T; Maxted, N

    2014-06-17

    Conserving crop wild relatives (CWR) is critical for maintaining food security. However, CWR-focused conservation plans are lacking, and are often based on the entire genus, even though only a few taxa are useful for crop improvement. We used taxonomic and geographic prioritisation to identify the best locations for in situ conservation of the most important (priority) CWR, using African cowpea (Vigna unguiculata (L.) Walp.) as a case study. Cowpea is an important crop for subsistence farmers in sub-Saharan Africa, yet its CWR are under-collected, under-conserved and under-utilised in breeding. We identified the most efficient sites to focus in situ cowpea CWR conservation and assessed whether priority CWR would be adequately represented in a genus-based conservation plan. We also investigated whether priority cowpea CWR are likely to be found in existing conservation areas and in areas important for mammal conservation. The genus-based method captured most priority CWR, and the distributions of many priority CWR overlapped with established conservation reserves and targets. These results suggest that priority cowpea CWR can be conserved by building on conservation initiatives established for other species.

  6. An implication of novel methodology to study pancreatic acinar mitochondria under in situ conditions.

    PubMed

    Manko, Bohdan O; Klevets, Myron Yu; Manko, Volodymyr V

    2013-03-01

    Mitochondria maintain numerous energy-consuming processes in pancreatic acinar cells, yet characteristics of pancreatic mitochondrial oxidative phosphorylation in native conditions are poorly studied. Besides, it is not known which type of solution is most adequate to preserve functions of pancreatic mitochondria in situ. Here we propose a novel experimental protocol suitable for in situ analysis of pancreatic mitochondria metabolic states. Isolated rat pancreatic acini were permeabilized with low doses of digitonin. Different metabolic states of mitochondria were examined in KCl- and sucrose-based solutions using Clark oxygen electrode. Respiration of digitonin-treated, unlike of intact, acini was substantially intensified by succinate or mixture of pyruvate plus malate. Substrate-stimulated respiration rate did not depend on solution composition. In sucrose-based solution, oligomycin inhibited State 3 respiration at succinate oxidation by 65.4% and at pyruvate plus malate oxidation by 60.2%, whereas in KCl-based solution, by 32.0% and 36.1%, respectively. Apparent respiratory control indices were considerably higher in sucrose-based solution. Rotenone or thenoyltrifluoroacetone severely inhibited respiration, stimulated by pyruvate plus malate or succinate, respectively. This revealed low levels of non-mitochondrial oxygen consumption of permeabilized acinar cells. These results suggest a stronger coupling between respiration and oxidative phosphorylation in sucrose-based solution.

  7. In situ infrared (FTIR) study of the mechanism of the borohydride oxidation reaction.

    PubMed

    Concha, B Molina; Chatenet, M; Maillard, F; Ticianelli, E A; Lima, F H B; de Lima, R B

    2010-10-07

    Early reports stated that Au was a catalyst of choice for the BOR because it would yield a near complete faradaic efficiency. However, it has recently been suggested that gold could yield to some extent the heterogeneous hydrolysis of BH, therefore lowering the electron count per BH, especially at low potential. Actually, the blur will exist regarding the BOR mechanism on Au as long as no physical proof regarding the reaction intermediates is not put forward. In that frame, in situ physical techniques like FTIR exhibit some interest to study the BOR. Consequently, in situ infrared reflectance spectroscopy measurements (SPAIRS technique) have been performed in 1 M NaOH/1 M NaBH(4) on a gold electrode with the aim to detect the intermediate species. We monitored several bands in B-H (nu ∼ 1180, 1080 and 972 cm(-1)) and B-O bond regions (nu = 1325 and ∼1425 cm(-1)), which appear sequentially as a function of the electrode polarization. These absorption bands are assigned to BH(3), BH(2) and BO species. At the light of the experimental results, possible initial elementary steps of the BOR on gold electrode have been proposed and discussed according to the relevant literature data.

  8. Er:YAG laser irradiation to control the progression of enamel erosion: an in situ study.

    PubMed

    Scatolin, R S; Colucci, V; Lepri, T P; Alexandria, A K; Maia, L C; Galo, R; Borsatto, M C; Corona, S A M

    2015-07-01

    This in situ study evaluated the effect of Er:YAG laser irradiation in controlling the progression of enamel erosion-like lesions. Fifty-six enamel slabs (330 KHN ± 10 %) with one fourth of the surface covered with resin composite (control area) were submitted to initial erosion-like lesion formation with citric acid. The slabs were divided into two groups: irradiated with Er:YAG laser and non-irradiated. Fourteen volunteers used an intraoral palatal appliance containing two slabs, in two phases of 5 days each. During the intraoral phase, in a crossed-over design, half of the volunteers immersed the appliance in citric acid while the other half used deionized water, both for 5 min, three times per day. Enamel wear was determined by an optical 3D profilometer. ANOVA revealed that when deionized water was used as immersion solution during the intraoral phase, lower values of wear were showed when compared with the groups that were eroded with citric acid, whether irradiated or non-irradiated with Er:YAG laser. When erosion with citric acid was performed, Er:YAG laser was not able to reduce enamel wear. Small changes on enamel surface were observed when it was irradiated with Er:YAG laser. It may be concluded that Er:YAG laser irradiation did not reduce the progression of erosive lesions on enamel submitted to in situ erosion with citric acid.

  9. An experimental system for high temperature X-ray diffraction studies with in situ mechanical loading

    SciTech Connect

    Oswald, Benjamin B.; Pagan, Darren C.; Miller, Matthew P.; Schuren, Jay C.

    2013-03-15

    An experimental system with in situ thermomechanical loading has been developed to enable high energy synchrotron x-ray diffraction studies of crystalline materials. The system applies and maintains loads of up to 2250 N in uniaxial tension or compression at a frequency of up to 100 Hz. The furnace heats the specimen uniformly up to a maximum temperature of 1200 Degree-Sign C in a variety of atmospheres (oxidizing, inert, reducing) that, combined with in situ mechanical loading, can be used to mimic processing and operating conditions of engineering components. The loaded specimen is reoriented with respect to the incident beam of x-rays using two rotational axes to increase the number of crystal orientations interrogated. The system was used at the Cornell High Energy Synchrotron Source to conduct experiments on single crystal silicon and polycrystalline Low Solvus High Refractory nickel-based superalloy. The data from these experiments provide new insights into how stresses evolve at the crystal scale during thermomechanical loading and complement the development of high-fidelity material models.

  10. An experimental system for high temperature X-ray diffraction studies with in situ mechanical loading

    PubMed Central

    Oswald, Benjamin B.; Schuren, Jay C.; Pagan, Darren C.; Miller, Matthew P.

    2013-01-01

    An experimental system with in situ thermomechanical loading has been developed to enable high energy synchrotron x-ray diffraction studies of crystalline materials. The system applies and maintains loads of up to 2250 N in uniaxial tension or compression at a frequency of up to 100 Hz. The furnace heats the specimen uniformly up to a maximum temperature of 1200 °C in a variety of atmospheres (oxidizing, inert, reducing) that, combined with in situ mechanical loading, can be used to mimic processing and operating conditions of engineering components. The loaded specimen is reoriented with respect to the incident beam of x-rays using two rotational axes to increase the number of crystal orientations interrogated. The system was used at the Cornell High Energy Synchrotron Source to conduct experiments on single crystal silicon and polycrystalline Low Solvus High Refractory nickel-based superalloy. The data from these experiments provide new insights into how stresses evolve at the crystal scale during thermomechanical loading and complement the development of high-fidelity material models. PMID:23556825

  11. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment.

    PubMed

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; Bittrich, Eva; Rauch, Sebastian; Uhlmann, Petra; Eichhorn, Klaus-Jochen; Seeber, Michael; Luzinov, Igor; Kilbey, S Michael; Lokitz, Bradley S; Minko, Sergiy; Hinrichs, Karsten

    2015-06-17

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes containing poly(N-isopropylacrylamide) and poly(acrylic acid) with high potential for biosensing and biomedical applications are studied by in situ infrared-spectroscopic ellipsometry (IRSE). IRSE is a highly sensitive nondestructive technique that allows protein adsorption on polymer brushes to be investigated in an aqueous environment as external stimuli, such as temperature and pH, are varied. These changes are relevant to conditions for regulation of protein adsorption and desorption for biotechnology, biocatalysis, and bioanalytical applications. Here brushes are used as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. The important finding of this work is that IRSE in the in situ experiments in protein solutions can distinguish between contributions of polymer brushes and proteins. The vibrational bands of the polymers provide insights into the hydration state of the brushes, whereas the protein-specific amide bands are related to changes of the protein secondary structure.

  12. Studies on In situ Hydrogel: A Smart Way for Safe and Sustained Ocular Drug Delivery

    PubMed Central

    Shastri, DH; Patel, LD; Parikh, RK

    2010-01-01

    The present work describes the formulation development of ophthalmic in situ gelling system using thermo-reversible gelling polymer, i.e. Pluronic F 127 (PF127). Because of high concentration (20 to 25%w/v) of this polymer required for in situ gelation causes irritation to the eye. So, to reduce this concentration, an attempt was made to combine the PF127 with other polymers like hydroxy propyl methyl cellulose (HPMC) as a viscosity increasing agent or with polymers like carbopol 940, xanthan gum, and sodium alginate (high glucuronic acid content) showing a pH and cation-triggered sol-gel transition, respectively. Different batches were prepared of varying concentrations of these polymers with PF127 using cromolyn sodium 2%w/v in phosphate buffer pH 5.0. The formulations were optimized by the viscosity measurement and in vitro gelation study. Selected formulations were evaluated for in vitro drug release profile and indicated sustain drug release over a period of 10 h. Effect of sterilization on drug content, pH, clarity, and viscosity were also evaluated. Finally, we concluded that by using this type of combination system, we could reduce not only the concentration of individual polymers but also the side effects without compromising the in vitro gelling capacity as well as overall rheology of the system. PMID:21264112

  13. Studies on In situ Hydrogel: A Smart Way for Safe and Sustained Ocular Drug Delivery.

    PubMed

    Shastri, Dh; Patel, Ld; Parikh, Rk

    2010-04-01

    The present work describes the formulation development of ophthalmic in situ gelling system using thermo-reversible gelling polymer, i.e. Pluronic F 127 (PF127). Because of high concentration (20 to 25%w/v) of this polymer required for in situ gelation causes irritation to the eye. So, to reduce this concentration, an attempt was made to combine the PF127 with other polymers like hydroxy propyl methyl cellulose (HPMC) as a viscosity increasing agent or with polymers like carbopol 940, xanthan gum, and sodium alginate (high glucuronic acid content) showing a pH and cation-triggered sol-gel transition, respectively. Different batches were prepared of varying concentrations of these polymers with PF127 using cromolyn sodium 2%w/v in phosphate buffer pH 5.0. The formulations were optimized by the viscosity measurement and in vitro gelation study. Selected formulations were evaluated for in vitro drug release profile and indicated sustain drug release over a period of 10 h. Effect of sterilization on drug content, pH, clarity, and viscosity were also evaluated. Finally, we concluded that by using this type of combination system, we could reduce not only the concentration of individual polymers but also the side effects without compromising the in vitro gelling capacity as well as overall rheology of the system.

  14. Fatty acid profile of the initial oral biofilm (pellicle): an in-situ study.

    PubMed

    Reich, Marco; Kümmerer, Klaus; Al-Ahmad, Ali; Hannig, Christian

    2013-09-01

    The first step of bioadhesion on dental surfaces is the formation of the acquired pellicle. This mainly acellular layer is formed instantaneously on all solid surfaces exposed to oral fluids. It is composed of proteins, glycoproteins and lipids. However, information on the lipid composition is sparse. The aim of the present study was to evaluate the fatty acid (FA) profile of the in-situ pellicle for the first time. Furthermore, the impact of rinses with safflower oil on the pellicle's FA composition was investigated. Pellicles were formed in situ on bovine enamel slabs mounted on individual upper jaw splints. The splints were carried by ten subjects over durations of 3-240 min. After comprehensive sample preparation, gas chromatography coupled with electron impact ionization mass spectrometry (GC-EI/MS) was used in order to characterize qualitatively and quantitatively a wide range of FA (C12-C24). The relative FA profiles of the pellicle samples gained from different subjects were remarkably similar, whereas the amount of FA showed significant interindividual variability. An increase in FA in the pellicle was observed over time. The application of rinses with safflower oil resulted in an accumulation of its specific FA in the pellicle. Pellicle formation is a highly selective process that does not correlate directly with salivary composition, as shown for FA.

  15. In Situ Ambient Pressure X-ray Photoelectron Spectroscopy Studies of Lithium-Oxygen Redox Reactions

    PubMed Central

    Lu, Yi-Chun; Crumlin, Ethan J.; Veith, Gabriel M.; Harding, Jonathon R.; Mutoro, Eva; Baggetto, Loïc; Dudney, Nancy J.; Liu, Zhi; Shao-Horn, Yang

    2012-01-01

    The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li4+xTi5O12/LiPON/LixV2O5 cell and examine in situ the chemistry of Li-O2 reaction products on LixV2O5 as a function of applied voltage under ultra high vacuum (UHV) and at 500 mtorr of oxygen pressure using ambient pressure X-ray photoelectron spectroscopy (APXPS). Under UHV, lithium intercalated into LixV2O5 while molecular oxygen was reduced to form lithium peroxide on LixV2O5 in the presence of oxygen upon discharge. Interestingly, the oxidation of Li2O2 began at much lower overpotentials (~240 mV) than the charge overpotentials of conventional Li-O2 cells with aprotic electrolytes (~1000 mV). Our study provides the first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O2 chemistry. PMID:23056907

  16. In situ disinfection of sewage contaminated shallow groundwater: a feasibility study.

    PubMed

    Bailey, Morgan M; Cooper, William J; Grant, Stanley B

    2011-11-01

    Sewage-contaminated shallow groundwater is a potential cause of beach closures and water quality impairment in marine coastal communities. In this study we set out to evaluate the feasibility of several strategies for disinfecting sewage-contaminated shallow groundwater before it reaches the coastline. The disinfection rates of Escherichia coli (EC) and enterococci bacteria (ENT) were measured in mixtures of raw sewage and brackish shallow groundwater collected from a coastal community in southern California. Different disinfection strategies were explored, ranging from benign (aeration alone, and aeration with addition of brine) to aggressive (chemical disinfectants peracetic acid (PAA) or peroxymonosulfate (Oxone)). Aeration alone and aeration with brine did not significantly reduce the concentration of EC and ENT after 6 h of exposure, while 4-5 mg L(-1) of PAA or Oxone achieved >3 log reduction after 15 min of exposure. Oxone disinfection was more rapid at higher salinities, most likely due to the formation of secondary oxidants (e.g., bromine and chlorine) that make this disinfectant inappropriate for marine applications. Using a Lagrangian modeling framework, we identify several factors that could influence the performance of in-situ disinfection with PAA, including the potential for bacterial regrowth, and the non-linear dependence of disinfection rate upon the residence time of water in the shallow groundwater. The data and analysis presented in this paper provide a framework for evaluating the feasibility of in-situ disinfection of shallow groundwater, and elucidate several topics that warrant further investigation.

  17. Structure-function analysis of vitamin D and VDR model.

    PubMed

    Yamada, S; Yamamoto, K; Masuno, H

    2000-05-01

    In the first section, the general three-dimensional structure of the ligand-binding domain (LBD) of nuclear receptors (NR) was briefly described on the basis of their x-ray crystal structures. Emphasis was placed on the three major conformations of NR-LBD and their role in the transactivation function. In the second part, the structure-function relationship of vitamin D was analyzed based on the ligand structure, in particular by using systematic conformational analysis as a tool. On the basis of the conformational analysis of the vitamin D side chain and studies using conformationally restricted synthetic vitamin D analogs, we suggested the active space region concept of vitamin D: The vitamin D side-chain region was grouped into five regions (A, G, EA, EG and F). Activity orders, in terms of the spatial region, found by these studies are as follows: Affinity for vitamin D receptor (VDR), EA>A>F>G>EG; Affinity for vitamin D binding protein (DBP), A>G,EA, EG; Target gene transactivation, EA>F>A>EG G; Cell differentiation, EA>F>A>EG G; Bone calcium mobilization, EA>G A>F EG; Intestinal calcium absorption, EA=A G>EG. In the third section, homology modeling of VDR-LBD and docking of the natural ligand, 1,25-(OH)2D3, into the ligand binding cavity of the model are described. Amino acid residues forming hydrogen bonds with the biologically important 1alpha- and 25-OH groups were identified: 1alpha-OH forms a pincer-type hydrogen bond with R274 and S237 and 25-OH with H397. This VDR-LBD/1,25-(OH)2D3 docking model was firmly substantiated by mutation analysis. Using this VDR model, the structure-function relationship of highly potent vitamin D analogs was discussed.

  18. Structure-function and regulation of ADAMTS13 protease

    PubMed Central

    Zheng, X. Long

    2013-01-01

    Summary ADAMTS13, a plasma reprolysin-like metalloprotease, cleaves von Willebrand factor (VWF). Severe deficiency of plasma ADAMTS13 activity results in thrombotic thrombocytopenic purpura (TTP), while mild to moderate deficiencies of plasma ADAMTS13 activity are emerging risk factors for developing myocardial and cerebral infarction, preeclampsia, and malignant malaria. Moreover, Adamts13−/− mice develop more severe inflammatory responses, leading to increased ischaemia/perfusion injury and formation of atherosclerosis. Structure-function studies demonstrate that the N-terminal portion of ADAMTS13 (MDTCS) is necessary and sufficient for proteolytic cleavage of VWF under various conditions and attenuation of arterial/venous thrombosis after oxidative injury. The more distal portion of ADAMTS13 (TSP1 2–8 repeats and CUB domains) may function as a disulphide bond reductase to prevent an elongation of ultra large VWF strings on activated endothelial cells and inhibit platelet adhesion/aggregation on collagen surface under flow. Remarkably, the proteolytic cleavage of VWF by ADAMTS13 is accelerated by FVIII and platelets under fluid shear stress. A disruption of the interactions between FVIII (or platelet glycoprotein 1bα) and VWF dramatically impairs ADAMTS13-dependent proteolysis of VWF in vitro and in vivo. These results suggest that FVIII and platelets may be physiological cofactors regulating VWF proteolysis. Finally, the structure-function and autoantibody mapping studies allow us to identify an ADAMTS13 variant with increased specific activity but reduced inhibition by autoantibodies in patients with acquired TTP. Together, these findings provide novel insight into the mechanism of VWF proteolysis and tools for the therapy of acquired TTP and perhaps other arterial thrombotic disorders. PMID:23809107

  19. Structure-Function Correlation of the Human Central Retina

    PubMed Central

    Charbel Issa, Peter; Troeger, Eric; Finger, Robert; Holz, Frank G.; Wilke, Robert; Scholl, Hendrik P. N.

    2010-01-01

    Background The impact of retinal pathology detected by high-resolution imaging on vision remains largely unexplored. Therefore, the aim of the study was to achieve high-resolution structure-function correlation of the human macula in vivo. Methodology/Principal Findings To obtain high-resolution tomographic and topographic images of the macula spectral-domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy (cSLO), respectively, were used. Functional mapping of the macula was obtained by using fundus-controlled microperimetry. Custom software allowed for co-registration of the fundus mapped microperimetry coordinates with both SD-OCT and cSLO datasets. The method was applied in a cross-sectional observational study of retinal diseases and in a clinical trial investigating the effectiveness of intravitreal ranibizumab in macular telangietasia type 2. There was a significant relationship between outer retinal thickness and retinal sensitivity (p<0.001) and neurodegeneration leaving less than about 50 µm of parafoveal outer retinal thickness completely abolished light sensitivity. In contrast, functional preservation was found if neurodegeneration spared the photoreceptors, but caused quite extensive disruption of the inner retina. Longitudinal data revealed that small lesions affecting the photoreceptor layer typically precede functional detection but later cause severe loss of light sensitivity. Ranibizumab was shown to be ineffective to prevent such functional loss in macular telangietasia type 2. Conclusions/Significance Since there is a general need for efficient monitoring of the effectiveness of therapy in neurodegenerative diseases of the retina and since SD-OCT imaging is becoming more widely available, surrogate endpoints derived from such structure-function correlation may become highly relevant in future clinical trials. PMID:20877651

  20. In situ synchrotron x-ray studies of ferroelectric thin films.

    SciTech Connect

    Fong, D. D.; Eastman, J. A.; Stephenson, G. B.; Fuoss, P. H.; Streiffer, S. K.; Thompson, C.; Auciello, O.; Materials Science Division; Northern Illinois Univ.

    2005-03-01

    In situ synchrotron X-ray scattering was used to observe both the growth of PbTiO{sub 3} films by metal-organic chemical vapor deposition and the behavior of the ferroelectric phase transition as a function of film thickness. The dependences of growth mode and deposition rate on gas flows and substrate temperature were determined by homoepitaxial growth studies on thick films (>50 nm). These studies facilitated the growth of thin coherently strained PbTiO{sub 3} films on SrTiO{sub 3} (001) substrates, with thicknesses ranging from 2 to 42 nm. Experiments on the ferroelectric phase transition as a function of film thickness were carried out in these films under controlled mechanical and electrical boundary conditions.

  1. Orthorhombic boron oxide under pressure: In situ study by X-ray diffraction and Raman scattering

    NASA Astrophysics Data System (ADS)

    Cherednichenko, Kirill A.; Le Godec, Yann; Kalinko, Aleksandr; Mezouar, Mohamed; Solozhenko, Vladimir L.

    2016-11-01

    High-pressure phase of boron oxide, orthorhombic β-B2O3, has been studied in situ by synchrotron X-ray diffraction to 22 GPa and Raman scattering to 46 GPa at room temperature. The bulk modulus of β-B2O3 has been found to be 169(3) GPa that is in good agreement with our ab initio calculations. Raman and IR spectra of β-B2O3 have been measured at ambient pressure; all experimentally observed bands have been attributed to the theoretically calculated ones, and the mode assignment has been performed. Based on the data on Raman shift as a function of pressure, combined with equation-of-state data, the Grüneisen parameters of all experimentally observed Raman bands have been calculated. β-B2O3 enriched by 10B isotope has been synthesized, and the effect of boron isotopic substitution on Raman spectra has been studied.

  2. In situ X-ray diffraction study on the growth kinetics of NiO nanoparticles.

    PubMed

    Meneses, C T; Almeida, J M A; Sasaki, J M

    2010-05-01

    The growth kinetics of NiO nanoparticles have been studied by in situ X-ray diffraction using two detection systems (conventional and imaging plate). NiO nanoparticles were formed by thermal decomposition after heating of an amorphous compound formed by the coprecipitation method. It was found that the detection method using an imaging plate is more efficient than the conventional detection mode for observing changes in the crystallite growth of nanocrystalline materials. Studies have been carried out to investigate the effects of the heating rates on the particles growth. The results suggest that the growth process of the particles is accelerated when the samples are treated at low heating rates. The evolution of particles size and the diffusion coefficient obtained from X-ray powder diffraction patterns are discussed in terms of the thermal conditions for the two types of detection.

  3. Multiphoton microscopy: an efficient tool for in-situ study of cultural heritage artifacts

    NASA Astrophysics Data System (ADS)

    Latour, Gaël.; Echard, Jean-Philippe; Didier, Marie; Schanne-Klein, Marie-Claire

    2013-05-01

    We present multimodal nonlinear optical imaging of historical artifacts by combining Two-Photon Excited Fluorescence (2PEF) and Second Harmonic Generation (SHG) microscopies. Three-dimensional (3D) non-contact laser-scanning imaging with micrometer resolution is performed without any preparation of the objects under study. 2PEF signals are emitted by a wide range of fluorophores such as pigments and binder, which can be discriminated thanks to their different emission spectral bands by using suitable spectral filters in the detection channel. SHG signals are specific for dense non-centrosymmetric organizations such as the crystalline cellulose within the wood cell walls. We also show that plaster particles exhibit SHG signals. These particles are bassanite crystals with a non-centrosymmetric crystalline structure, while the other types of calcium sulphates exhibit a centrosymmetric crystalline structure with no SHG signal. In our study, we first characterize model single-layered samples: wood, gelatin-based films containing plaster or cochineal lake and sandarac film containing cochineal lake. We then study multilayered coating systems on wood and show that multimodal nonlinear microscopy successfully reveals the 3D distribution of all components within the stratified sample. We also show that the fine structure of the wood can be assessed, even through a thick multilayered varnish coating. Finally, in situ multimodal nonlinear imaging is demonstrated in a historical violin. SHG/2PEF imaging thus appears as an efficient non-destructive and contactless 3D imaging technique for in situ investigation of historical coatings and more generally for wood characterization and coating analysis at micrometer scale.

  4. Extracting Neutron Structure Functions in the Resonance Region

    SciTech Connect

    Yonatan Kahn

    2009-07-01

    A new iterative method is presented for extracting neutron structure functions from inclusive structure functions of nuclei, focusing specifically on the resonance region. Unlike earlier approaches, this method is applicable to both spin-averaged and spin-dependent structure functions. We show that in numerical tests, this method is able to reproduce known input functions of nearly arbitrary shape after only 5–10 iterations. We illustrate the method on extractions of F2n and g1,2n from data, and discuss the treatment of systematic errors from this extraction procedure.

  5. In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Yingxuan; Zang, Ling; Jacobs, Daniel L.; Zhao, Jie; Yue, Xiu; Wang, Chuanyi

    2017-02-01

    Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction-relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes.

  6. Kinetics of Methane Hydrate Decomposition Studied via in Situ Low Temperature X-ray Powder Diffraction

    SciTech Connect

    Everett, Susan M; Rawn, Claudia J; Keffer, David J.; Mull, Derek L; Payzant, E Andrew; Phelps, Tommy Joe

    2013-01-01

    Gas hydrates are known to have a slowed decomposition rate at ambient pressure and temperatures below the melting point of ice termed self-preservation or anomalous preservation. As hydrate exothermically decomposes, gas is released and water of the clathrate cages transforms into ice. Two regions of slowed decomposition for methane hydrate, 180 200 K and 230 260 K, were observed, and the kinetics were studied by in situ low temperature x-ray powder diffraction. The kinetic constants for ice formation from methane hydrate were determined by the Avrami model within each region and activation energies, Ea, were determined by the Arrhenius plot. Ea determined from the data for 180 200 K was 42 kJ/mol and for 230 260 K was 22 kJ/mol. The higher Ea in the colder temperature range was attributed to a difference in the microstructure of ice between the two regions.

  7. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

    SciTech Connect

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; Bittrich, Eva; Rauch, Sebastian; Uhlmann, Petra; Eichhorn, Klaus-Jochen; Seeber, Michael; Luzinov, Igor; Kilbey, S. Michael; Lokitz, Bradley S.; Minko, Sergiy; Hinrichs, Karsten

    2015-02-10

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes with high potential for biosensing and biomedical applications are studied by in-situ infrared-spectroscopic ellipsometry (IRSE). IRSE as a highly sensitive non-destructive technique allows us to investigate protein adsorption on polymer brushes in aqueous environment in dependence of external stimuli like temperature and pH. These stimuli are, for instance, relevant in switchable mixed brushes containing poly(N-isopropyl acrylamide) and poly(acrylic acid), respectively. We use such brushes as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. IRSE can distinguish between polymer-specific vibrational bands, which yield insights into the hydration state of the brushes, and changes in the protein-specific amide bands, which are related to changes of the protein secondary structure.

  8. In Situ Infrared Ellipsometry for Protein Adsorption Studies on Ultrathin Smart Polymer Brushes in Aqueous Environment

    DOE PAGES

    Kroning, Annika; Furchner, Andreas; Aulich, Dennis; ...

    2015-02-10

    The protein-adsorbing and -repelling properties of various smart nanometer-thin polymer brushes with high potential for biosensing and biomedical applications are studied by in-situ infrared-spectroscopic ellipsometry (IRSE). IRSE as a highly sensitive non-destructive technique allows us to investigate protein adsorption on polymer brushes in aqueous environment in dependence of external stimuli like temperature and pH. These stimuli are, for instance, relevant in switchable mixed brushes containing poly(N-isopropyl acrylamide) and poly(acrylic acid), respectively. We use such brushes as model surfaces for controlling protein adsorption of human serum albumin and human fibrinogen. IRSE can distinguish between polymer-specific vibrational bands, which yield insights intomore » the hydration state of the brushes, and changes in the protein-specific amide bands, which are related to changes of the protein secondary structure.« less

  9. Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders

    NASA Astrophysics Data System (ADS)

    Nlebedim, I. C.; Ucar, Huseyin; Hatter, Christine B.; McCallum, R. W.; McCall, Scott K.; Kramer, M. J.; Paranthaman, M. Parans

    2017-01-01

    Considerations for achieving high degree of alignment in polymer bonded permanent magnets are presented via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. The thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees with an observed correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.

  10. In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles.

    PubMed

    Li, Yingxuan; Zang, Ling; Jacobs, Daniel L; Zhao, Jie; Yue, Xiu; Wang, Chuanyi

    2017-02-13

    Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction-relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes.

  11. Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders

    DOE PAGES

    Nlebedim, I. C.; Ucar, Huseyin; Hatter, Christine B.; ...

    2016-08-30

    We presented some considerations for achieving high degree of alignment in polymer bonded permanent magnets via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. Moreover, the thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees withmore » an observed correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Finally, manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.« less

  12. In Situ Nanoindentation Studies on Detwinning and Work Hardening in Nanotwinned Monolithic Metals

    SciTech Connect

    Liu, Y.; Li, N.; Bufford, D.; Lee, J. H.; Wang, J.; Wang, H.; Zhang, X.

    2015-07-14

    Certain nanotwinned (nt) metals have rare combinations of high mechanical strength and ductility. Here, we review recent in situ nanoindentation studies (using transmission electron microscopes) on the deformation mechanisms of nt face-centered cubic metals including Cu, Ni, and Al with a wide range of stacking fault energy (SFE). Moreover, in nt Cu with low-to-intermediate SFE, detwinning (accompanied by rapid twin boundary migration) occurs at ultralow stress. In Ni with relatively high SFE, coherent {111} twin boundaries lead to substantial work hardening. Twinned Al has abundant {112} incoherent twin boundaries, which induce significant work-hardening capability and plasticity in Al. Finally, twin boundaries in Al also migrate but at very high stresses. Furthermore, molecular dynamics simulations reveal the influence of SFE on deformation mechanisms in twinned metals.

  13. Strain relaxation in He implanted UO2 polycrystals under thermal treatment: An in situ XRD study

    NASA Astrophysics Data System (ADS)

    Palancher, H.; Kachnaoui, R.; Martin, G.; Richard, A.; Richaud, J.-C.; Onofri, C.; Belin, R.; Boulle, A.; Rouquette, H.; Sabathier, C.; Carlot, G.; Desgardin, P.; Sauvage, T.; Rieutord, F.; Raynal, J.; Goudeau, Ph.; Ambard, A.

    2016-08-01

    Within the frame of the long-term evolution of spent nuclear fuel in dry disposal, the behavior of He in UO2 polycrystals has to be studied. Here, strain relaxation in He implanted samples has been characterized using in situ X-ray diffraction during thermal annealing. The influence of a wide range of experimental parameters (annealing atmosphere, He ion energy, orientation of the UO2 grains probed by X-rays) has been evaluated. If each of them contributes to the strain relaxation kinetics in the implanted layer, strain relaxation is not completed for temperatures below 900 °C which is equivalent to what has been found on He implanted UO2 single crystals, or aged UO2 pellets doped with α-emitters. In the case of implantation with 500 keV He ions, we clearly show that strain relaxation and He release are not correlated for temperatures below 750 °C.

  14. In-Situ Studies of Intercritically Austempered Ductile Iron Using Neutron Diffraction

    SciTech Connect

    Druschitz, Alan; Aristizabal, Ricardo; Druschitz, Edward; Hubbard, Camden R; Watkins, Thomas R; Walker, Larry R; Ostrander, M

    2012-01-01

    Intercritically austempered ductile irons hold promise for applications requiring fatigue durability, excellent castability, low production energy requirements, reduced greenhouse gas emissions and excellent machinability. In the present study, four different ductile iron alloys, containing manganese and nickel as the primary austenite-stabilizing elements, were heat treated to obtain different quantities of austenite in the final microstructure. This paper reports the microstructures and phases present in these alloys. Further, lattice strains and diffraction elastic constants in various crystallographic directions and the transformation characteristics of the austenite as a function of applied stress were determined using in-situ loading with neutron diffraction at the second generation Neutron Residual Stress Facility (NRSF2) at the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL).

  15. In situ neutron scattering study of nanostructured PbTe-PbS bulk thermoelectric material

    SciTech Connect

    Ren, Fei; Schmidt, Robert D; Case, Eldon D; An, Ke

    2016-01-01

    Nanostructures play an important role in thermoelectric materials. Their thermal stability, such as phase change and evolution at elevated temperatures, is thus of great interest to the thermoelectric community. In this study, in situ neutron diffraction was used to examine the phase evolution of nanostructured bulk PbTe-PbS materials fabricated using hot pressing and pulsed electrical current sintering (PECS). The PbS second phase was observed in all samples in the as-pressed condition. The temperature dependent lattice parameter and phase composition data show an initial formation of PbS precipitates followed by a redissolution during heating. The redissolution process started around 570 600 K, and completed at approximately 780 K. During cooling, the PECS sample followed a reversible curve while the heating/cooling behavior of the hot pressed sample was irreversible.

  16. Proximal deletion of chromosome 21 confirmed by in situ hybridization and molecular studies

    SciTech Connect

    Courtens, W.; Peterson, M.B.; Noeel, J.C.; Flament-Durand, J.; Van Regemorter, N.; Delneste, D.; Cochaux, P.; Verschraegen-Spae, M.R.; Van Roy, N.; Speleman, F.

    1994-07-01

    Foetal blood sampling was performed at 35 weeks of gestation due to abnormal foetal ultrasound findings. There was apparent monosomy 21 (45,XX,-21) in all mitoses analyzed. The infant died at 37 weeks during delivery. Examination disclosed facial anomalies, clubfeet, hypoplasia of the left urogenital tract, agenesis of corpus callosum, ventricular dilatation, and heterotopias. Reevaluation of the karyotype showed an unbalanced translocation (1;21) (q44;q22.11) which resulted from a maternal balanced translocation. These findings were confirmed by fluorescence in situ hybridization and molecular studies with chromosome 21 specific markers. The latter showed a proximal deletion of the maternally derived chromosome 21 including all loci from centrometer down to the D21S210 locus. This case illustrates the need for complementary cytogenetic and molecular investigations in cases of apparent monosomy 21. 41 refs., 4 figs., 2 tabs.

  17. In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles

    PubMed Central

    Li, Yingxuan; Zang, Ling; Jacobs, Daniel L.; Zhao, Jie; Yue, Xiu; Wang, Chuanyi

    2017-01-01

    Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction–relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes. PMID:28194017

  18. In situ synchrotron X-ray diffraction study of hydrides in Zircaloy-4 during thermomechanical cycling

    NASA Astrophysics Data System (ADS)

    Cinbiz, Mahmut N.; Koss, Donald A.; Motta, Arthur T.; Park, Jun-Sang; Almer, Jonathan D.

    2017-04-01

    The d-spacing evolution of both in-plane and out-of-plane hydrides has been studied using in situ synchrotron radiation X-ray diffraction during thermo-mechanical cycling of cold-worked stress-relieved Zircaloy-4. The structure of the hydride precipitates is such that the δ{111} d-spacing of the planes aligned with the hydride platelet face is greater than the d-spacing of the 111 planes aligned with the platelet edges. Upon heating from room temperature, the δ{111} planes aligned with hydride plate edges exhibit bi-linear thermally-induced expansion. In contrast, the d-spacing of the (111) plane aligned with the hydride plate face initially contracts upon heating. These experimental results can be understood in terms of a reversal of stress state associated with precipitating or dissolving hydride platelets within the α-zirconium matrix.

  19. Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders

    SciTech Connect

    Nlebedim, I. C.; Ucar, Huseyin; Hatter, Christine B.; McCallum, R. W.; McCall, Scott K.; Kramer, M. J.; Paranthaman, M. Parans

    2016-08-30

    We presented some considerations for achieving high degree of alignment in polymer bonded permanent magnets via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. Moreover, the thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees with an observed correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Finally, manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.

  20. In situ microscopic studies on the structural and chemical behaviors of lithium-ion battery materials

    NASA Astrophysics Data System (ADS)

    Shao, Minhua

    2014-12-01

    The direct observation of the microstructural evolution and state-of-charge (SOC) distribution in active materials is crucial to understand the lithiation/delithiation mechanisms during electrochemical cycling of lithium-ion batteries (LIBs). Owing to their high spatial resolutions and capability to map chemical states by combining other spectroscopic techniques, microscopic techniques including X-ray fluorescence (XRF) microscopy, Raman microscopy, transmission X-ray microscopy (TXM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) play significant roles in real time monitoring the dynamic changes in the LIB electrodes and materials. This paper reviews the recent progress of using in situ microscopic techniques to study LIB materials, including Si-, Sn-, Ge-, C- and metal oxides-based anode materials, and layered oxysulfide, metal fluorides, LiCoO2, LiNi0.8Co0.15Al0.05O2, LiMn2O4, LiFePO4 cathode materials.

  1. EXAFS investigations of metal organic molecules with the goal of studying homogeneously catalytic systems in situ

    NASA Astrophysics Data System (ADS)

    Ertel, T. S.; Hörner, W.; Hückmann, S.; Kolb, U.; Abraham, I.; Bertagnolli, H.

    1995-02-01

    The investigations of Grignard compounds are very instructive for understanding the principles of getting structural information on highly complex and simultaneously metal activated systems by means of EXAFS spectroscopy. The structural investigations of a model system for Friedel-Crafts alkylation and some metal complexes (metal = Zr, Mo, W, Re), which activate carbonyl groups selectively with respect to the subsequent ring cleavage of axially prosterogenic biaryl lactones, are reported. As an actual field of metal organic research temperature dependent in situ EXAFS studies of the CH-activation of substituted olefins are presented. It was possible to observe the course of the rearrangement reaction of an iridium olefin complex to the corresponding hydrido (vinyl) iridium complex.

  2. In Situ Nanoindentation Studies on Detwinning and Work Hardening in Nanotwinned Monolithic Metals

    DOE PAGES

    Liu, Y.; Li, N.; Bufford, D.; ...

    2015-07-14

    Certain nanotwinned (nt) metals have rare combinations of high mechanical strength and ductility. Here, we review recent in situ nanoindentation studies (using transmission electron microscopes) on the deformation mechanisms of nt face-centered cubic metals including Cu, Ni, and Al with a wide range of stacking fault energy (SFE). Moreover, in nt Cu with low-to-intermediate SFE, detwinning (accompanied by rapid twin boundary migration) occurs at ultralow stress. In Ni with relatively high SFE, coherent {111} twin boundaries lead to substantial work hardening. Twinned Al has abundant {112} incoherent twin boundaries, which induce significant work-hardening capability and plasticity in Al. Finally, twinmore » boundaries in Al also migrate but at very high stresses. Furthermore, molecular dynamics simulations reveal the influence of SFE on deformation mechanisms in twinned metals.« less

  3. In-Situ TEM Study of Interface Sliding and Migration in an Ultrafine Lamellar Structure

    SciTech Connect

    Hsiung, L M

    2005-12-06

    The instability of interfaces in an ultrafine TiAl-({gamma})/Ti{sub 3}Al-({alpha}{sub 2}) lamellar structure by straining at room temperature has been investigated using in-situ straining techniques performed in a transmission electron microscope. The purpose of this study is to obtain experimental evidence to support the creep mechanisms based upon the interface sliding in association with a cooperative movement of interfacial dislocations previously proposed to interpret the nearly linear creep behavior observed from ultrafine lamellar TiAl alloys. The results have revealed that both the sliding and migration of lamellar interfaces can take place simultaneously as a result of the cooperative movement of interfacial dislocations.

  4. Advanced sample environments for in situ neutron diffraction studies of nuclear materials

    NASA Astrophysics Data System (ADS)

    Reiche, Helmut Matthias

    Generation IV nuclear reactor concepts, such as the supercritical-water-cooled nuclear reactor (SCWR), are actively researched internationally. Operating conditions above the critical point of water (374°C, 22.1 MPa) and fuel core temperature that potentially exceed 1850°C put a high demand on the surrounding materials. For their safe application, it is essential to characterize and understand the material properties on an atomic scale such as crystal structure and grain orientation (texture) changes as a function of temperature and stress. This permits the refinement of models predicting the macroscopic behavior of the material. Neutron diffraction is a powerful tool in characterizing such crystallographic properties due to their deep penetration depth into condensed matter. This leads to the ability to study bulk material properties, as opposed to surface effects, and allows for complex sample environments to study e.g. the individual contributions of thermo-mechanical processing steps during manufacturing, operating or accident scenarios. I present three sample environments for in situ neutron diffraction studies that provide such crystallographic information and have been successfully commissioned and integrated into the user program of the High Pressure -- Preferred Orientation (HIPPO) diffractometer at the Los Alamos Neutron Science Center (LANSCE) user facility. I adapted a sample changer for reliable and fast automated texture measurements of multiple specimens. I built a creep furnace combining a 2700 N load frame with a resistive vanadium furnace, capable of temperatures up to 1000°C, and manipulated by a pair of synchronized rotation stages. This combination allows following deformation and temperature dependent texture and strain evolutions in situ. Utilizing the presented sample changer and creep furnace we studied pressure tubes made of Zr-2.5wt%Nb currently employed in CANDURTM nuclear reactors and proposed for future SCWRs, acting as the primary

  5. Kinetics and Mechanism of Ultrasonic Activation of Persulfate: An in Situ EPR Spin Trapping Study.

    PubMed

    Wei, Zongsu; Villamena, Frederick A; Weavers, Linda K

    2017-03-21

    Ultrasound (US) was shown to activate persulfate (PS) providing an alternative activation method to base or heat as an in situ chemical oxidation (ISCO) method. The kinetics and mechanism of ultrasonic activation of PS were examined in aqueous solution using an in situ electron paramagnetic resonance (EPR) spin trapping technique and radical trapping with probe compounds. Using the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), hydroxyl radical ((•)OH) and sulfate radical anion (SO4(•-)) were measured from ultrasonic activation of persulfate (US-PS). The yield of (•)OH was up to 1 order of magnitude greater than that of SO4(•-). The comparatively high (•)OH yield was attributed to the hydrolysis of SO4(•-) in the warm interfacial region of cavitation bubbles formed from US. Using steady-state approximations, the dissociation rate of PS in cavitating bubble systems was determined to be 3 orders of magnitude greater than control experiments without sonication at ambient temperature. From calculations of the interfacial volume surrounding cavitation bubbles and using the Arrhenius equation, an effective mean temperature of 340 K at the bubble-water interface was estimated. Comparative studies using the probe compounds tert-butyl alcohol and nitrobenzene verified the bubble-water interface as the location for PS activation by high temperature with (•)OH contributing a minor role in activating PS to SO4(•-). The mechanisms unveiled in this study provide a basis for optimizing US-PS as an ISCO technology.

  6. Anaerobic in situ biodegradation of TNT using whey as an electron donor: a case study.

    PubMed

    Innemanová, Petra; Velebová, Radka; Filipová, Alena; Čvančarová, Monika; Pokorný, Petr; Němeček, Jan; Cajthaml, Tomáš

    2015-12-25

    Contamination by 2,4,6-trinitrotoluene (TNT), an explosive extensively used by the military, represents a serious environmental problem. In this study, whey has been selected as the most technologically and economically suitable primary substrate for anaerobic in situ biodegradation of TNT. Under laboratory conditions, various additions of whey, molasses, acetate and activated sludge as an inoculant were tested and the process was monitored using numerous chemical analyses including phospholipid fatty acid analysis. The addition of whey resulted in the removal of more than 90% of the TNT in real contaminated soil (7 mg kg(-1) and 12 mg kg(-1) of TNT). The final bioremediation strategy was suggested on the basis of the laboratory results and tested under real conditions at a TNT contaminated site in the Czech Republic. During the pilot test, three repeated injections of whey suspension into the sandy aquifer were performed over a 10-month period. In total, approximately 5m(3) of whey were used. A substantial decrease in the TNT groundwater concentration from the original levels (equalling 1.49 mg l(-1) to 8.58 mg l(-1)) was observed in most of the injection wells, while the concentrations of the TNT biotransformation products were found to be elevated. Pilot-scale application results showed that the anoxic and/or anaerobic conditions in the aquifer were sufficient for TNT bio-reduction by autochthonous microorganisms. Whey application was not accompanied by undesirable effects such as a substantial decrease in the pH or clogging of the wells. The results of the study document the suitability of application of whey to bioremediate TNT contaminated sites in situ.

  7. Study of Relationship between In-Situ Stress and Fluid Conduits in Hongchailin of Ilan Plain, NE Taiwan

    NASA Astrophysics Data System (ADS)

    Kao, T. E.; Yeh, E. C.; Wu, F. Y.; Wang, T. T.; Hung, J. H.; Song, S. R.

    2015-12-01

    Ilan plan in northeastern Taiwan possesses abundant geothermal resources resulted from a higher geothermal gradient due to the influences of compression of mountain building and extension of back-arc rifting. Understanding in-situ stress field can evaluate current extension state for benefiting geothermal exploration and development and providing important information to geothermal engineering. Because development of geothermal fluid conduits is highly depended on in-situ stress, for enhancing geothermal productivity, this study conducted Anelastic Strain Recovery (ASR) and core description to study the relationship between in-situ stress and fluid conduits in Hongchailin area, Ilan Plain. Based on experiments of ASR, this study assessed in-situ 3D stress field including stress direction. Information of fractures and veins with depth obtained from core observation provided insights into the distribution of fluid conduits. Current results display a mixing stress regime of normal faulting and strike-slip faulting with NW-SE compression and SW-NE extension, which is consistent with results of focal mechanisms. Results of core description showed E-W striking gouge, indicating an early N-S compression. The fluid conduits with NW-SE strike are consistent with the predicted conduits inferred from in-situ stress field. Integrating with other information of stress direction and magnitude will provide insights into developing enhanced geothermal systems and utilizing geothermal energy efficiently.

  8. Ionospheric Cubeswarm Concept Study: using low-resource instrumentation for truly multipoint in situ ionospheric observations

    NASA Astrophysics Data System (ADS)

    Hampton, D.; Lynch, K. A.; Earle, G. D.; Mannucci, A. J.; Clayton, R.; Fisher, L. E.; Fernandes, P. A.; Roberts, M.; Zettergren, M. D.

    2015-12-01

    Magnetosphere-ionosphere coupling currents close in the nightside lower ionosphere. These spatially inhomogeneous and time varying volume currents are difficult to capture with in situ observations. Our understanding of M-I coupling systems is limited by our understanding of the actual structure of ionospheric current closure. A path forward includes assimilation of a variety of data sets into increasingly capable ionospheric models. While each data set provides only a piece of the picture, the assimilation process allows optimal use of each piece.An important development for the necessary in situ observations involves making them truly multi-point, and therefore, low-resource. For thermal particle observations, the high densities of the lower ionosphere allow the use of low-gain (current-sensing rather than particle-counting) particle sensors. One observational goal is the definition of the actual structure of ionospheric closure currents. This can be approached with a number of different measurement techniques, in tandem with an ionospheric model, since the closure currents need to follow the rules of electrodynamics and current continuity. Low resource thermal plasma sensors such as retarding potential analyzers and drift meters can provide valuable measurements of plasma parameters, including density and plasma flow, without the need for high voltages or deployable boom systems. These low-resource measurements, which can be reproduced on arrays of in situ observation platforms, used in tandem with proper plasma physics interpretation of their signatures in the disturbed observing environment, and as part of an assimilated data set into an ionospheric model, can allow us to progress in our understanding of ionospheric structuring and its effects on auroral coupling. Now, with increasingly capable multipoint arrays of spacecraft, and quantitative 2D-with-time context from cameras and imagery, we are moving toward truly multipoint studies of the system

  9. Squark contributions to photon structure functions and positivity constraints

    SciTech Connect

    Kitadono, Yoshio; Yoshida, Yutaka; Sahara, Ryo; Uematsu, Tsuneo

    2011-10-01

    Photon structure functions in supersymmetric QCD are investigated in terms of the parton model where squark contributions are evaluated. We calculate the eight virtual photon structure functions by taking the discontinuity of the squark massive one-loop diagrams of the photon-photon forward amplitude. The model-independent positivity constraints derived from the Cauchy-Schwarz inequalities are satisfied by the squark parton model calculation and actually the two equality relations hold for the squark contribution. We also show that our polarized photon structure function g{sub 1}{sup {gamma}} for the real photon leads to the vanishing first moment sum rule, and the constraint |g{sub 1}{sup {gamma}}|{<=}F{sub 1}{sup {gamma}} is satisfied by the real photon. We also discuss a squark signature in the structure function W{sub TT}{sup {tau}}.

  10. Models of Protocellular Structure, Function and Evolution

    NASA Technical Reports Server (NTRS)

    New, Michael H.; Pohorille, Andrew; Szostak, Jack W.; Keefe, Tony; Lanyi, Janos K.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    In the absence of any record of protocells, the most direct way to test our understanding, of the origin of cellular life is to construct laboratory models that capture important features of protocellular systems. Such efforts are currently underway in a collaborative project between NASA-Ames, Harvard Medical School and University of California. They are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures. The centerpiece of this project is a method for the in vitro evolution of protein enzymes toward arbitrary catalytic targets. A similar approach has already been developed for nucleic acids in which a small number of functional molecules are selected from a large, random population of candidates. The selected molecules are next vastly multiplied using the polymerase chain reaction.

  11. The nonsinglet structure function evolution by Laplace method

    SciTech Connect

    Boroun, G. R. E-mail: boroun@razi.ac.ir; Zarrin, S.

    2015-12-15

    We derive a general scheme for the evolution of the nonsinglet structure function at the leadingorder (LO) and next-to-leading-order (NLO) by using the Laplace-transform technique. Results for the nonsinglet structure function are compared with MSTW2008, GRV, and CKMT parameterizations and also EMC experimental data in the LO and NLO analysis. The results are in good agreement with the experimental data and other parameterizations in the low- and large-x regions.

  12. Structure-function relationships of antimicrobial peptides.

    PubMed

    Hwang, P M; Vogel, H J

    1998-01-01

    Antimicrobial peptides are ubiquitously produced throughout nature. Many of these relatively short peptides (6-50 residues) are lethal towards bacteria and fungi, yet they display minimal toxicity towards mammalian cells. All of the peptides are highly cationic and hydrophobic. It is widely believed that they act through nonspecific binding to biological membranes, even though the exact nature of these interactions is presently unclear. High-resolution nuclear magnetic resonance (NMR) has contributed greatly to knowledge in this field, providing insight about peptide structure in aqueous solution, in organic cosolvents, and in micellar systems. Solid-state NMR can provide additional information about peptide-membrane binding. Here we review our current knowledge about the structure of antimicrobial peptides. We also discuss studies pertaining to the mechanism of action. Despite the different three-dimensional structural motifs of the various classes, they all have similar amphiphilic surfaces that are well-suited for membrane binding. Many antimicrobial peptides bind in a membrane-parallel orientation, interacting only with one face of the bilayer. This may be sufficient for antimicrobial action. At higher concentrations, peptides and phospholipids translocate to form multimeric transmembrane channels that seem to contribute to the peptide's hemolytic activity. An understanding of the key features of the secondary and tertiary structures of the antimicrobial peptides and their effects on bactericidal and hemolytic activity can aid the rational design of improved analogs for clinical use.

  13. Models of Protocellular Structure, Function and Evolution

    NASA Technical Reports Server (NTRS)

    New, Michael H.; Pohorille, Andrew; Szostak, Jack W.; Keefe, Tony; Lanyi, Janos K.

    2001-01-01

    In the absence of any record of protocells, the most direct way to test our understanding of the origin of cellular life is to construct laboratory models that capture important features of protocellular systems. Such efforts are currently underway in a collaborative project between NASA-Ames, Harvard Medical School and University of California. They are accompanied by computational studies aimed at explaining self-organization of simple molecules into ordered structures. The centerpiece of this project is a method for the in vitro evolution of protein enzymes toward arbitrary catalytic targets. A similar approach has already been developed for nucleic acids in which a small number of functional molecules are selected from a large, random population of candidates. The selected molecules are next vastly multiplied using the polymerase chain reaction. A mutagenic approach, in which the sequences of selected molecules are randomly altered, can yield further improvements in performance or alterations of specificities. Unfortunately, the catalytic potential of nucleic acids is rather limited. Proteins are more catalytically capable but cannot be directly amplified. In the new technique, this problem is circumvented by covalently linking each protein of the initial, diverse, pool to the RNA sequence that codes for it. Then, selection is performed on the proteins, but the nucleic acids are replicated. Additional information is contained in the original extended abstract.

  14. Beta-secretase: Structure, Function, and Evolution

    PubMed Central

    Venugopal, Chitra; Demos, Christina M.; Rao, K. S. Jagannatha; Pappolla, Miguel A.; Sambamurti, Kumar

    2010-01-01

    The most popular current hypothesis is that Alzheimer’s disease (AD) is caused by aggregates of the amyloid peptide (Aβ), which is generated by cleavage of the Aβ protein precursor (APP) by β-secretase (BACE-1) followed by γ-secretase. BACE-1 cleavage is limiting for the production of Aβ, making it a particularly good drug target for the generation of inhibitors that lower Aβ. A landmark discovery in AD was the identification of BACE-1 (a.k.a. Memapsin-2) as a novel class of type I transmembrane aspartic protease. Although BACE-2, a homologue of BACE-1, was quickly identified, follow up studies using knockout mice demonstrated that BACE-1 was necessary and sufficient for most neuronal Aβ generation. Despite the importance of BACE-1 as a drug target, development has been slow due to the incomplete understanding of its function and regulation and the difficulties in developing a brain penetrant drug that can specifically block its large catalytic pocket. This review summarizes the biological properties of BACE-1 and attempts to use phylogenetic perspectives to understand its function. The article also addresses the challenges in discovering a selective drug-like molecule targeting novel mechanisms of BACE-1 regulation. PMID:18673212

  15. Pentraxins: Structure, Function, and Role in Inflammation

    PubMed Central

    Du Clos, Terry W.

    2013-01-01

    The pentraxins are an ancient family of proteins with a unique architecture found as far back in evolution as the Horseshoe crab. In humans the two members of this family are C-reactive protein and serum amyloid P. Pentraxins are defined by their sequence homology, their pentameric structure and their calcium-dependent binding to their ligands. Pentraxins function as soluble pattern recognition molecules and one of the earliest and most important roles for these proteins is host defense primarily against pathogenic bacteria. They function as opsonins for pathogens through activation of the complement pathway and through binding to Fc gamma receptors. Pentraxins also recognize membrane phospholipids and nuclear components exposed on or released by damaged cells. CRP has a specific interaction with small nuclear ribonucleoproteins whereas SAP is a major recognition molecule for DNA, two nuclear autoantigens. Studies in autoimmune and inflammatory disease models suggest that pentraxins interact with macrophage Fc receptors to regulate the inflammatory response. Because CRP is a strong acute phase reactant it is widely used as a marker of inflammation and infection. PMID:24167754

  16. Small catalytic RNA: Structure, function and application

    SciTech Connect

    Monforte, J.A.

    1991-04-01

    We have utilized a combination of photochemical cross-linking techniques and site-directed mutagenesis to obtain secondary and tertiary structure information for the self-cleaving, self-ligating subsequence of RNA from the negative strand of Satellite Tobacco Ringspot Virus. We have found that the helical regions fold about a hinge to promoting four different possible tertiary interactions, creating a molecular of similar shape to a paperclip. A model suggesting that the paperclip'' and hammerhead'' RNAs share a similar three dimensional structure is proposed. We have used a self-cleaving RNA molecule related to a subsequence of plant viroids, a hammerhead,'' to study the length-dependent folding of RNA produced during transcription by RNA polymerase. We have used this method to determine the length of RNA sequestered within elongating E. coli and T7 RNA polymerase complexes. The data show that for E. coli RNA polymerase 12{plus minus}1 nucleotides are sequestered within the ternary complex, which is consistent with the presence of an RNA-DNA hybrid within the transcription bubble, as proposed by others. The result for T7 RNA polymerase differs from E. coli RNA polymerase, with only 10{plus minus}1 nucleotides sequestered within the ternary complex, setting a new upper limit for the minimum RNA-DNA required for a stable elongating complex. Comparisons between E. coli and T7 RNA polymerase are made. The relevance of the results to models or transcription termination, abortive initiation, and initiation to elongation mode transitions are discussed.

  17. A quantified dosing ALD reactor with in-situ diagnostics for surface chemistry studies

    NASA Astrophysics Data System (ADS)

    Larrabee, Thomas J.

    A specialized atomic layer deposition (ALD) reactor has been constructed to serve as an instrument to simultaneously study the surface chemistry of the ALD process, and perform ALD as is conventionally done in continuum flow of inert gas. This reactor is uniquely useful to gain insight into the ALD process because of the combination of its precise, controllable, and quantified dosing/microdosing capability; its in-situ quadrupole mass spectrometer for gas composition analysis; its pair of highly-sensitive in-situ quartz crystal microbalances (QCMs); and its complete spectrum of pressures and operating conditions --- from viscous to molecular flow regimes. Control of the dose is achieved independently of the conditions by allowing a reactant gas to fill a fixed volume and measured pressure, which is held at a controlled temperature, and subsequently dosed into the system by computer controlled pneumatic valves. Absolute reactant exposure to the substrate and QCMs is unambiguously calculated from the molecular impingement flux, and its relationship to dose size is established, allowing means for easily intentionally reproducing specific exposures. Methods for understanding atomic layer growth and adsorption phenomena, including the precursor sticking probability, dynamics of molecular impingement, size of dose, and other operating variables are for the first time quantitatively related to surface reaction rates by mass balance. Extensive characterization of the QCM as a measurement tool for adsorption under realistic ALD conditions has been examined, emphasizing the state-of-the-art and importance of QCM system features required. Finally, the importance of dose-quantification and microdosing has been contextualized in view of the ALD literature, underscoring the significance of more precise condition specification in establishing a better basis for reactor and reactant comparison.

  18. Influence of in situ stress variations on acoustic emissions: a numerical study

    NASA Astrophysics Data System (ADS)

    Zhao, Qi; Tisato, Nicola; Grasselli, Giovanni; Mahabadi, Omid K.; Lisjak, Andrea; Liu, Qinya

    2015-11-01

    The study of acoustic emissions (AEs) is of paramount importance to understand rock deformation processes. AE recorded during laboratory experiments mimics, in a controlled geometry and environment, natural and induced seismicity. However, these experiments are destructive, time consuming and require a significant amount of resources. Lately, significant progresses have been made in numerical simulations of rock failure processes, providing detailed insights into AE. We utilized the 2-D combined finite-discrete element method to simulate the deformation of Stanstead Granite under varying confining pressure (Pc) and demonstrated that the increase of confining pressure, Pc, (i) shifts failures from tensile towards shear dominated and (ii) enhance the macroscopic ductility. We quantitatively describe the AE activity associated with the fracturing process by assessing the spatial fractal dimension (D-value), the temporal distribution (AE rate) and the slope of the frequency-magnitude distribution (b-value). Based on the evaluation of D-value and AE rate, we defined two distinct deformation phases: Phase I and Phase II. The influence of Pc on the spatial distribution of AE varies according to the deformation phase: for increasing Pc, D-value decreases and increases during Phases I and II, respectively. In addition, b-value decreases with increasing Pc during the entire experiment. Our numerical results show for the first time that variations of D- and b-values as a function of in situ stress can be simulated using the combined finite-discrete element approach. We demonstrate that the examination of seismicity should be carried out carefully, taking into consideration the deformation phase and in situ stress conditions.

  19. Corrosion in Haas expanders with and without use of an antimicrobial agent: an in situ study

    PubMed Central

    BAGATIN, Cristhiane Ristum; ITO, Izabel Yoko; ANDRUCIOLI, Marcela Cristina Damião; NELSON-FILHO, Paulo; FERREIRA, José Tarcísio Lima

    2011-01-01

    Objectives The purpose of this study was to evaluate in situ the occurrence of corrosion in the soldering point areas between the wire, silver brazing and band in Haas expanders. Material and Methods Thirty-four 7-12-year-old patients who needed maxillary expansion with a Haas expander were randomly assigned to two groups of 17 individuals each, according to the oral hygiene protocol adopted during the orthodontic treatment: Group I (control), toothbrushing with a fluoride dentifrice and Group II (experimental), toothbrushing with the same dentifrice plus 0.12% chlorhexidine gluconate (Periogard®) mouthrinses twice a week. The appliances were removed after approximately 4 months. Fragments of the appliances containing a metallic band with a soldered wire were sectioned at random for examination by stereomicroscopy, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Data were analyzed statistically by Fisher's test at 5% significance level. Results The analysis by optical microscopy revealed areas with color change suggestive of corrosion in the soldering point areas joining the band and the wire in all specimens of both groups, with no statistically significant difference between the groups (p=1). The peaks of chemical elements (Ni, Fe, Cr, O, C and P) revealed by EDS were also similar in both groups. Conclusion: Color changes and peaks of chemical elements suggestive of corrosion were observed in the soldering point areas between the wire, silver brazing and band in both control and experimental groups, which indicate that the 0.12% chlorhexidine gluconate mouthrinses did not influence the occurrence of corrosion in situ. PMID:22231004

  20. Study of environmental radioactivity in Palestine by in situ gamma-ray spectroscopy.

    PubMed

    Lahham, Adnan; Al-Masri, Hussein; Judeh, Adnan

    2009-07-01

    This work presents qualitative and quantitative evaluation of environmental radioactivity in the central and southern areas of the West Bank, Palestine. For this purpose, the technology of in situ gamma-ray spectroscopy is used with a scintillation of 7.6 x 7.6 cm NaI(Tl) crystal connected to multichannel analyzer InSpector 2000 from Canberra instruments and laptop computer. Gamma-ray spectra were collected using the detector placed 1 m above the ground surface. Calibration of the detection system for in situ measurements of gamma-emitting radionuclides in open terrain is performed theoretically using Monte Carlo techniques. Measurements are conducted in 18 locations in 3 regions across the West Bank. The vast majority of identified radionuclides are naturally occurring gamma-emitting sources (the decay products of (238)U, (232)Th and (40)K). The only identified anthropogenic radionuclide is (137)Cs. Activity concentrations of (40)K, (238)U, (232)Th as well as the total outdoor gamma dose rate from these radionuclides were determined from the gamma-ray spectra. The highest activity concentrations of the three primordial radionuclides were 203 Bq kg(-1) for (40)K, 32 Bq kg(-1) for (238)U and 30 Bq kg(-1) for (232)Th. The total outdoor gamma dose rate calculated for the whole study area at 1 m above ground ranged from 6 to 30 nGy h(-1) with a mean of 18 +/- 7 nGy h(-1), which represents about 30% of the world average value.

  1. In situ XAS studies of Pt{sub x}Pd{sub 1-x} nanoparticles under thermal annealing

    SciTech Connect

    Bernardi, F.; Morais, J.; Alves, M. C. M.

    2009-01-29

    In this work, we have studied Pt{sub x}Pd{sub 1-x}(x = 1, 0.7 or 0.5) nanoparticles subjected to H{sub 2} reduction and sulfidation under H{sub 2}S atmosphere, both at 300 deg. C. The system was studied by in-situ x-ray absorption spectroscopy (in-situ XAS). We observed that the efficiency of sulfidation is directly proportional to the quantity of Pd atoms in the nanoparticle, provided the reduction process has been achieved.

  2. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction.

    PubMed

    Moorhouse, Saul J; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  3. The Oxford-Diamond In Situ Cell for studying chemical reactions using time-resolved X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Moorhouse, Saul J.; Vranješ, Nenad; Jupe, Andrew; Drakopoulos, Michael; O'Hare, Dermot

    2012-08-01

    A versatile, infrared-heated, chemical reaction cell has been assembled and commissioned for the in situ study of a range of chemical syntheses using time-resolved energy-dispersive X-ray diffraction (EDXRD) on Beamline I12 at the Diamond Light Source. Specialized reactor configurations have been constructed to enable in situ EDXRD investigation of samples under non-ambient conditions. Chemical reactions can be studied using a range of sample vessels such as alumina crucibles, steel hydrothermal autoclaves, and glassy carbon tubes, at temperatures up to 1200 °C.

  4. Small catalytic RNA: Structure, function and application

    SciTech Connect

    Monforte, J.A.

    1991-04-01

    We have utilized a combination of photochemical cross-linking techniques and site-directed mutagenesis to obtain secondary and tertiary structure information for the self-cleaving, self-ligating subsequence of RNA from the negative strand of Satellite Tobacco Ringspot Virus. We have found that the helical regions fold about a hinge to promoting four different possible tertiary interactions, creating a molecular of similar shape to a paperclip. A model suggesting that the ``paperclip`` and ``hammerhead`` RNAs share a similar three dimensional structure is proposed. We have used a self-cleaving RNA molecule related to a subsequence of plant viroids, a ``hammerhead,`` to study the length-dependent folding of RNA produced during transcription by RNA polymerase. We have used this method to determine the length of RNA sequestered within elongating E. coli and T7 RNA polymerase complexes. The data show that for E. coli RNA polymerase 12{plus_minus}1 nucleotides are sequestered within the ternary complex, which is consistent with the presence of an RNA-DNA hybrid within the transcription bubble, as proposed by others. The result for T7 RNA polymerase differs from E. coli RNA polymerase, with only 10{plus_minus}1 nucleotides sequestered within the ternary complex, setting a new upper limit for the minimum RNA-DNA required for a stable elongating complex. Comparisons between E. coli and T7 RNA polymerase are made. The relevance of the results to models or transcription termination, abortive initiation, and initiation to elongation mode transitions are discussed.

  5. Plasticity and ultra-low stress induced twin boundary migration in nanotwinned Cu by in situ nanoindentation studies

    SciTech Connect

    Liu, Y.; Chen, Y.; Jian, J.; Wang, H.; Zhang, X.

    2014-06-09

    Nanotwinned metals have rare combinations of mechanical strength and ductility. Previous studies have shown that detwinning occurs in plastically deformed nanotwinned metals. Although molecular dynamics simulations have predicted that fine nanotwins can migrate at low stress, there is little in situ evidence to validate such predictions. Also it is unclear if detwinning occurs prior to or succeeding plastic yielding. Here, by using in situ nanoindentation in a transmission electron microscope, we show that a non-elastic detwinning process in nanotwinned Cu occurred at ultra-low indentation stress (0.1 GPa), well before the stress necessary for plastic yielding. Furthermore, the in situ nanoindentation technique allows us to differentiate dislocation-nucleation dominated microscopic yielding preceding macroscopic yielding manifested by dislocation-transmission through twin boundaries. This study thus provides further insights for understanding plasticity in nanotwinned metals at microscopic levels.

  6. Quantitative In Situ TEM Studies of Small-Scale Plasticity in Irradiated and Unirradiated Metals

    NASA Astrophysics Data System (ADS)

    Chisholm, Claire

    mechanical data, as the two defect conditions exhibit similar yield strengths, ultimate tensile strengths, and number and size of load-drops. This similarity implies that, even if materials contain dissimilar individual defects, the collective defect behavior can result in similar mechanical properties. Thus, the origin of mechanical properties can be ambiguous and caution should be taken when extrapolating to different size scales. Furthermore, such similarities highlight the importance of in-situ observation during deformation. These experiments provide a key test of theory, by providing a local test of behavior, which is much more stringent than testing behaviors averaged over many regions. Advanced electron microscopy imaging techniques and quantitative in-situ TEM tensile tests are performed with Au thin-film as a model FCC structural material. These investigations highlight the various hurdles experimental studies must overcome in order to probe defect behavior at a fundamental level. Two novelly-applied strain mapping techniques are performed to directly measure the matrix strain around helium bubbles in He1+ implanted Au thin-film. Dark-field inline holography (DFIH) is applied here for the first time to a metal, and nano-beam electron diffraction (NBED) transient strain mapping is shown to be experimentally feasible using the high frame rate Gatan K2 camera. The K2 camera reduces scan times from ˜18 minutes to 82 seconds for a 128x256 pixel scan at 400 fps. Both methods measure a peak strain around 10 nm bubbles of 0.7%, correlating to an internal pressure of 580 MPa, or a vacancy to helium ion ratio of 1V:2.4He. Previous studies have relied on determining the appropriate equation of state to relate measured or approximated helium density to internal bubble pressure and thus strain. Direct measurement of the surrounding matrix strain through DFIH and NBED methods effectively bypasses this step, allowing for easier defect interaction modeling as the bubble can be

  7. Mantle cell lymphoma with in situ or mantle zone growth pattern: a study of five cases and review of literature.

    PubMed

    Hsu, Peihong; Yang, Tianyu; Sheikh-Fayyaz, Silvat; Brody, Judith; Bandovic, Jela; Roy, Sarma; Laser, Jordan; Kolitz, Jonathan E; Devoe, Craig; Zhang, Xinmin

    2014-01-01

    We present two rare cases of in situ mantle cell lymphoma ("in situ MCL") and three cases of MCL with mantle zone growth pattern (MCL-MZGP). The patients include four males and one female, with a median age of 66 years (range, 52 to 86 years). Two present with isolated lymphadenopathy and three with multiple lymphadenopathy. At presentation, the complete blood count (CBC) and serum lactate dehydrogenase (LDH) are normal in all cases. Histologic examination reveals an in situ pattern in two cases and a mantle zone growth pattern in three cases. The staging bone marrow biopsies show minimal involvement by lymphoma in one case and no morphologic evidence of lymphoma in four cases. All cases are positive for cyclin D1, including two with typical MCL phenotype and three with CD5-negativity. Four out of five cases express kappa light chain. FISH study for t(11;14) is performed in three cases, of which one is positive and two are inconclusive. For four patients with a median follow-up of 38 months, three are in clinical remission and one has persistent disease. In conclusion, the "in situ MCL" is associated with incidental finding, indolent clinical course and lower tumor burden. The predominant usage of kappa light chain and frequent CD5-negativity observed in our cases are unusual. We review the clinical and laboratory features of "in situ MCL" cases in the literature.

  8. [Histometric study of 55 cases of carcinoma in situ and microinvasive carcinoma of the cervix. Histogenetic deductions].

    PubMed

    Brémond, A; Dargent, D; Lesbros, F

    1976-01-01

    The authors present the results of a quantitative study of carcinoma-in-situ and occult invasive cancers of the cervix. 40 separate carcinomata in-situ were measured and the limits of their topography precisely defined with reference to the external os on the one hand and the "last gland" on the other. It is known that this gland is situated at the site of the original junction between the cylindrical and pavement epithelia. It confirms that carcinoma-in-situ always (with few exceptions) develops upwards from the area of the original junction between the cylindrical and pavement epithelia, and its topography is higher than that of dysplasia especially when the two types of lesion are associated.

  9. Spatial variances of wind fields and their relation to second-order structure functions and spectra

    NASA Astrophysics Data System (ADS)

    Vogelzang, Jur; King, Gregory P.; Stoffelen, Ad

    2015-02-01

    Kinetic energy variance as a function of spatial scale for wind fields is commonly estimated either using second-order structure functions (in the spatial domain) or by spectral analysis (in the frequency domain). Both techniques give an order-of-magnitude estimate. More accurate estimates are given by a statistic called spatial variance. Spatial variances have a clear interpretation and are tolerant for missing data. They can be related to second-order structure functions, both for discrete and continuous data. Spatial variances can also be Fourier transformed to yield a relation with spectra. The flexibility of spatial variances is used to study various sampling strategies, and to compare them with second-order structure functions and spectral variances. It is shown that the spectral sampling strategy is not seriously biased to calm conditions for scatterometer ocean surface vector winds. When the second-order structure function behaves like rp, its ratio with the spatial variance equals >(p+1>)>(p+2>). Ocean surface winds in the tropics have p between 2/3 and 1, so one-sixth to one-fifth of the second-order structure function value is a good proxy for the cumulative variance.

  10. Trade Study of Five In-Situ Propellant Production System for a Mars Sample Return Mission

    NASA Technical Reports Server (NTRS)

    Green, S. T.; Deffenbaugh, D. M.; Miller, M. A.

    1999-01-01

    One of the goals of NASA''s HEDS enterprise is to establish a long-term human presence on Mars at a fraction of the cost of employing today''s technology. The most direct method of reducing mission cost is to reduce the launch mass of the spacecraft. If the propellants for the return phase of the mission are produced on Mars, the total spacecraft mass could be reduced significantly. An interim goal is a Mars Sample Return (MSR) mission, which is proposed to demonstrate the feasibility of in-situ propellant production (ISPP). Five candidate ISPP systems for producing two fuels and oxygen from the Martian atmosphere are considered in this design trade-off study:(1) Zirconia cell with methanol synthesis, (2) Reverse water gas shift (RWGS) with water electrolysis and methanol synthesis, (3) Sabatier process for methane production with water electrolysis, (4) Sabatier process with water electrolysis and partial methane pyrolysis, and (5) Sabatier/RWGS combination with water electrolysis. These systems have been the subject of numerous previous analytical studies and laboratory demonstrations. In this investigation, the systems are objectively compared on the basis of thermochemical performance models using a commonly used chemical plant analysis software package. The realistic effects of incomplete chemical conversion and gas phase separator performance are included in these models. This study focuses on the chemical processing and product separation subsystems. The CO2 compression upstream of the chemical plane and the liquefaction/storage components are not included here.

  11. Operable Unit 7-13/14 in situ thermal desorption treatability study work plan

    SciTech Connect

    Shaw, P.; Nickelson, D.; Hyde, R.

    1999-05-01

    This Work Plan provides technical details for conducting a treatability study that will evaluate the application of in situ thermal desorption (ISTD) to landfill waste at the Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). ISTD is a form of thermally enhanced vapor vacuum extraction that heats contaminated soil and waste underground to raise its temperature and thereby vaporize and destroy most organics. An aboveground vapor vacuum collection and treatment system then destroys or absorbs the remaining organics and vents carbon dioxide and water to the atmosphere. The technology is a byproduct of an advanced oil-well thermal extraction program. The purpose of the ISTD treatability study is to fill performance-based data gaps relative to off-gas system performance, administrative feasibility, effects of the treatment on radioactive contaminants, worker safety during mobilization and demobilization, and effects of landfill type waste on the process (time to remediate, subsidence potential, underground fires, etc.). By performing this treatability study, uncertainties associated with ISTD as a selected remedy will be reduced, providing a better foundation of remedial recommendations and ultimate selection of remedial actions for the SDA.

  12. Multislice simulations for in-situ HRTEM studies of nanostructured magnesium hydride at ambient hydrogen pressure.

    PubMed

    Surrey, Alexander; Schultz, Ludwig; Rellinghaus, Bernd

    2017-01-31

    The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a "nanoreactor" is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH2, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies.

  13. Using pancreas tissue slices for in situ studies of islet of Langerhans and acinar cell biology.

    PubMed

    Marciniak, Anja; Cohrs, Christian M; Tsata, Vasiliki; Chouinard, Julie A; Selck, Claudia; Stertmann, Julia; Reichelt, Saskia; Rose, Tobias; Ehehalt, Florian; Weitz, Jürgen; Solimena, Michele; Slak Rupnik, Marjan; Speier, Stephan

    2014-12-01

    Studies on the cellular function of the pancreas are typically performed in vitro on its isolated functional units, the endocrine islets of Langerhans and the exocrine acini. However, these approaches are hampered by preparation-induced changes of cell physiology and the lack of an intact surrounding. We present here a detailed protocol for the preparation of pancreas tissue slices. This procedure is less damaging to the tissue and faster than alternative approaches, and it enables the in situ study of pancreatic endocrine and exocrine cell physiology in a conserved environment. Pancreas tissue slices facilitate the investigation of cellular mechanisms underlying the function, pathology and interaction of the endocrine and exocrine components of the pancreas. We provide examples for several experimental applications of pancreas tissue slices to study various aspects of pancreas cell biology. Furthermore, we describe the preparation of human and porcine pancreas tissue slices for the validation and translation of research findings obtained in the mouse model. Preparation of pancreas tissue slices according to the protocol described here takes less than 45 min from tissue preparation to receipt of the first slices.

  14. Androgen Receptor Structure, Function and Biology: From Bench to Bedside

    PubMed Central

    Davey, Rachel A; Grossmann, Mathis

    2016-01-01

    The actions of androgens such as testosterone and dihydrotestosterone are mediated via the androgen receptor (AR), a ligand-dependent nuclear transcription factor and member of the steroid hormone nuclear receptor family. Given its widespread expression in many cells and tissues, the AR has a diverse range of biological actions including important roles in the development and maintenance of the reproductive, musculoskeletal, cardiovascular, immune, neural and haemopoietic systems. AR signalling may also be involved in the development of tumours in the prostate, bladder, liver, kidney and lung. Androgens can exert their actions via the AR in a DNA binding-dependent manner to regulate target gene transcription, or in a non-DNA binding-dependent manner to initiate rapid, cellular events such as the phosphorylation of 2nd messenger signalling cascades. More recently, ligand-independent actions of the AR have also been identified. Given the large volume of studies relating to androgens and the AR, this review is not intended as an extensive review of all studies investigating the AR, but rather as an overview of the structure, function, signalling pathways and biology of the AR as well as its important role in clinical medicine, with emphasis on recent developments in this field. PMID:27057074

  15. The fate of fixed nitrogen in marine sediments with low organic loading: an in situ study

    NASA Astrophysics Data System (ADS)

    Bonaglia, Stefano; Hylén, Astrid; Rattray, Jayne E.; Kononets, Mikhail Y.; Ekeroth, Nils; Roos, Per; Thamdrup, Bo; Brüchert, Volker; Hall, Per O. J.

    2017-01-01

    Over the last decades, the impact of human activities on the global nitrogen (N) cycle has drastically increased. Consequently, benthic N cycling has mainly been studied in anthropogenically impacted estuaries and coasts, while in oligotrophic systems its understanding is still scarce. Here we report on benthic solute fluxes and on rates of denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) studied by in situ incubations with benthic chamber landers during two cruises to the Gulf of Bothnia (GOB), a cold, oligotrophic basin located in the northern part of the Baltic Sea. Rates of N burial were also inferred to investigate the fate of fixed N in these sediments. Most of the total dissolved fixed nitrogen (TDN) diffusing to the water column was composed of organic N. Average rates of dinitrogen (N2) production by denitrification and anammox (range: 53-360 µmol N m-2 day-1) were comparable to those from Arctic and subarctic sediments worldwide (range: 34-344 µmol N m-2 day-1). Anammox accounted for 18-26 % of the total N2 production. Absence of free hydrogen sulfide and low concentrations of dissolved iron in sediment pore water suggested that denitrification and DNRA were driven by organic matter oxidation rather than chemolithotrophy. DNRA was as important as denitrification at a shallow, coastal station situated in the northern Bothnian Bay. At this pristine and fully oxygenated site, ammonium regeneration through DNRA contributed more than one-third to the TDN efflux and accounted, on average, for 45 % of total nitrate reduction. At the offshore stations, the proportion of DNRA in relation to denitrification was lower (0-16 % of total nitrate reduction). Median value and range of benthic DNRA rates from the GOB were comparable to those from the southern and central eutrophic Baltic Sea and other temperate estuaries and coasts in Europe. Therefore, our results contrast with the view that DNRA is negligible in cold and well

  16. In situ transmission electron microscopy studies of mechanical properties of one-dimensional nanostructures

    NASA Astrophysics Data System (ADS)

    Jaroenapibal, Papot

    The unique high-aspect ratio and low mass properties of intrinsic one-dimensional (1-D) nanostructures offer an opportunity for the development of ultra-sensitive nanoresonator-based devices. This dissertation studies the mechanical properties of various 1-D nanostructures, including single-walled carbon nanotubes (SWNTs), SWNT bundles, C60-filled SWNT bundles, and gallium nitride (GaN) nanowires, through observation of their mechanical resonances in a transmission electron microscope. A special specimen holder was custom designed and built to actuate these materials to their resonance through an applied tunable ac signal. The Euler-Bernoulli beam theory is employed to relate the measured resonant frequency to the sample's elastic modulus. These studies illustrate the increased importance of surface and interfacial interactions in materials at these length-scales to the mechanical properties of these structures. For SWNT bundles, the bending modulus E decreases with increasing bundle diameters, and is found to be in the range of 70 +/- 6 to 442 +/- 36 GPa for bundle diameters between 11-68 nm. Inter-tube shear is believed to be responsible for these results. The onset of nonlinear frequency response is observed in these bundles upon large excitation amplitudes. We also studied the effects of structural modifications on the mechanical properties of these bundles through the creation of cross links between nanotubes in the bundled structures, and through the introduction of C60 molecules to the hollow inner area of the nanotube structure. Significant enhancement in the stiffness is observed after the bundle is irradiated with low to moderate electron doses, since inter-tube shear is prohibited. In the C60 SWNT structures, we observe a similar diameter-dependent bending modulus; yet, the modulus is significantly higher than the unfilled system. We also attempt to measure the mechanical properties of isolated individual SWNTs. With the combined uses of focused ion beam

  17. The effects of in situ freezing on the anterior cruciate ligament. An experimental study in goats.

    PubMed

    Jackson, D W; Grood, E S; Cohn, B T; Arnoczky, S P; Simon, T M; Cummings, J F

    1991-02-01

    We developed an in situ freeze-thaw model designed to simulate an ideally placed and oriented autogenous graft of the anterior cruciate ligament. In this model, the anterior cruciate ligament was exposed, and the femoral insertion, tibial insertion, and body of the anterior cruciate ligament were frozen in situ with specially designed freezing probes. Freeze-thaw cycles were repeated five times. We used the technique in thirty-three mature goats to study the biological and biomechanical outcomes of the devitalized and devascularized anterior cruciate ligament at zero, six, and twenty-six weeks after treatment. Thus, the collagen fibers of the simulated autogenous graft remain in normal anatomical position and the simulated graft is fixed under physiological tension. At twenty-six weeks, no statistically significant differences were noted between treated and contralateral control (untreated) ligaments relative to anterior-posterior translation, maximum force to rupture, stiffness in the linear region of the force-length curve, modulus of elasticity in the linear region, strain to maximum stress, or maximum stress. The only statistically significant difference was an increase in cross-sectional area of the ligament. This increase was 22 and 42 per cent greater than that in the control ligaments at six weeks and six months. At six months, the ligaments in the control group had an average mid-cross-sectional area of 17.7 +/- 1.2 square millimeters and the ligaments in the experimental group, 25.2 +/- 3.1 square millimeters. Changes in the size and density of the collagen fibrils also were demonstrated at six months. These observations are in sharp contrast to our previous studies of replacement of the anterior cruciate ligament, in which an allograft of the ligament or an allograft supplemented with a 3M ligament augmentation device (LAD; 3M, St. Paul, Minnesota) was used. In those studies, an average reduction in maximum strength of 75 per cent for the allografts and

  18. Airborne Sunphotometer Studies of Aerosol Properties and Effects, Including Closure Among Satellite, Suborbital Remote, and In situ Measurements

    NASA Technical Reports Server (NTRS)

    Russlee, Philip B.; Schmid, B.; Redemann, J.; Livingston, J. M.; Bergstrom, R. W.; Ramirez, S. A.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    Airborne sunphotometry has been used to measure aerosols from North America, Europe, and Africa in coordination with satellite and in situ measurements in TARFOX (1996), ACE-2 (1997), PRIDE (2000), and SAFARI 2000. Similar coordinated measurements of Asian aerosols are being conducted this spring in ACE-Asia and are planned for North American aerosols this summer in CLAMS. This paper summarizes the approaches used, key results, and implications for aerosol properties and effects, such as single scattering albedo and regional radiative forcing. The approaches exploit the three-dimensional mobility of airborne sunphotometry to access satellite scenes over diverse surfaces (including open ocean with and without sunglint) and to match exactly the atmospheric layers sampled by airborne in situ measurements and other radiometers. These measurements permit tests of the consistency, or closure, among such diverse measurements as aerosol size-resolved chemical composition; number or mass concentration; light extinction, absorption, and scattering (total, hemispheric back and 180 deg.); and radiative fluxes. In this way the airborne sunphotometer measurements provide a key link between satellite and in situ measurements that helps to understand any discrepancies that are found. These comparisons have led to several characteristic results. Typically these include: (1) Better agreement among different types of remote measurements than between remote and in situ measurements. (2) More extinction derived from transmission measurements than from in situ measurements. (3) Larger aerosol absorption inferred from flux radiometry than from in situ measurements. Aerosol intensive properties derived from these closure studies have been combined with satellite-retrieved fields of optical depth to produce fields of regional radiative forcing. We show results for the North Atlantic derived from AVHRR optical depths and aerosol intensive properties from TARFOX and ACE-2. Companion papers

  19. Weldon Spring, Missouri, Raffinate Pits 1, 2, 3, and 4: Preliminary grout development screening studies for in situ waste immobilization

    SciTech Connect

    McDaniel, E.W.; Gilliam, T.M.; Dole, L.R.; West, G.A.

    1987-04-01

    Results of Oak Ridge National Laboratory's initial support program to develop a preliminary grout formula to solidify in situ the Weldon Spring waste are presented. The screening study developed preliminary formulas based on a simulated composite waste and then tested the formulas on actual waste samples. Future data needs are also discussed. 1 ref., 6 figs., 9 tabs.

  20. The Impact of the Structure, Function, and Resources of the Campus Security Office on Campus Safety

    ERIC Educational Resources Information Center

    Bennett, Patricia Anne

    2012-01-01

    The topic of this dissertation is college and university safety. This national quantitative study utilized resource dependency theory to examine relationships between the incidence of reported campus crimes and the structure, function, and resources of campus security offices. This study uncovered a difference in reported total crime rates,…

  1. Studies on in situ particulate reinforced tin-silver composite solders relevant to thermomechanical fatigue issues

    NASA Astrophysics Data System (ADS)

    Choi, Sunglak

    2001-07-01

    Global pressure based on environmental and health concerns regarding the use of Pb-bearing solder has forced the electronics industry to develop Pb-free alternative solders. Eutectic Sn-Ag solder has received much attention as a potential Pb-free candidate to replace Sn-Pb solder. Since introduction of surface mount technology, packaging density increased and the electronic devices became smaller. As a result, solders in electronic modules are forced to function as a mechanical connection as well as electrical contact. Solders are also exposed to very harsh service conditions such as automotive under-the-hood and aerospace applications. Solder joints experience thermomechanical fatigue, i.e. interaction of fatigue and creep, during thermal cycling due to temperature fluctuation in service conditions. Microstructural study on thermomechanical fatigue of the actual eutectic Sn-Ag and Sn-4Ag-0.5Cu solder joints was performed to better understand deformation and damage accumulation occurring during service. Incorporation of reinforcements has been pursued to improve the mechanical and particularly thermomechanical behavior of solders, and their service temperature capability. In-situ Sn-Ag composite solders were developed by incorporating Cu 6Sn5, Ni3Sn4, and FeSn2 particulate reinforcements in the eutectic Sn-Ag solder in an effort to enhance thermomechanical fatigue resistance. In-situ composite solders were investigated on the growth of interfacial intermetallic layer between solder and Cu substrate growth and creep properties. Solder joints exhibited significant deformation and damage on free surface and interior regions during thermomechanical fatigue. Cracks initiated on the free surface of the solder joints and propagated toward interior regions near the substrate of the solder joint. Crack grew along Sn grain boundaries by grain boundary sliding. There was significant residual stress within the solder joint causing more damage. Presence of small amount of Cu

  2. Integration of space and in situ observations to study global climate change

    NASA Technical Reports Server (NTRS)

    Bengtsson, L.; Shukla, J.

    1988-01-01

    The use of model-based global data sets of atmospheric circulation for studying fundamental dynamical and physical processes is discussed, focusing on limitations of the available model-based data sets. Data from the Global Weather Experiment in 1979 were analyzed by two authorized level IIIb data centers in 1980 and in 1981. The analyses led to difference in data-sparse regions such as the tropics. Study areas which can be addressed by an internally-consistent long-term multivariate data set for the atmospheric circulation are considered, including mean climate, forcing for the ocean models, global hydrological cycle, atmospheric energetics, intraseasonal variability, land surface processes, and structure and variability of vertical velocity, divergence, and diabatic heating. It is concluded that the most comprehensive technique for integrating space and in situ observations to produce this type of data set would be a four-dimensional data assimilation system with a realistic physical model of the type employed in operational numerical weather prediction.

  3. Bioreactor tests preliminary to landfill in situ aeration: a case study.

    PubMed

    Raga, Roberto; Cossu, Raffaello

    2013-04-01

    Lab scale tests in bioreactor were carried out in the framework of the characterization studies of a landfill where in situ aeration (possibly followed by landfill mining) had been proposed as part of the novel waste management strategy in a region in northern Italy. The tests were run to monitor the effects produced by aerobic conditions at different temperatures on waste sampled at different depths in the landfill, with focus on the carbon and nitrogen conversion during aeration. Temperatures ranging from 35 to 45°C were chosen, in order to evaluate possible inhibition of biodegradation processes (namely nitrification) at 45°C in the landfill. The results obtained showed positive effects of the aeration on leachate quality and a significant reduction of waste biodegradability. Although a delay of biodegradation processes was observed in the reactor run at 45°C, biodegradation rates increased after 2 months of aeration, providing very low values of the relevant parameters (as in the other aerated reactors) by the end of the study. Mass balances were carried out for TOC and NNH4(+); the findings obtained were encouraging and provided evidence of the effectiveness of carbon and nitrogen conversion processes in the aerated landfill simulation reactors.

  4. Bioreactor tests preliminary to landfill in situ aeration: A case study

    SciTech Connect

    Raga, Roberto; Cossu, Raffaello

    2013-04-15

    Highlights: ► Carbon and nitrogen mass balances in aerated landfill simulation reactors. ► Waste stabilization in aerated landfill simulation reactors. ► Effect of temperature on biodegradation processes in aerated landfills. - Abstract: Lab scale tests in bioreactor were carried out in the framework of the characterization studies of a landfill where in situ aeration (possibly followed by landfill mining) had been proposed as part of the novel waste management strategy in a region in northern Italy. The tests were run to monitor the effects produced by aerobic conditions at different temperatures on waste sampled at different depths in the landfill, with focus on the carbon and nitrogen conversion during aeration. Temperatures ranging from 35 to 45 °C were chosen, in order to evaluate possible inhibition of biodegradation processes (namely nitrification) at 45 °C in the landfill. The results obtained showed positive effects of the aeration on leachate quality and a significant reduction of waste biodegradability. Although a delay of biodegradation processes was observed in the reactor run at 45 °C, biodegradation rates increased after 2 months of aeration, providing very low values of the relevant parameters (as in the other aerated reactors) by the end of the study. Mass balances were carried out for TOC and N-NH{sub 4}{sup +}; the findings obtained were encouraging and provided evidence of the effectiveness of carbon and nitrogen conversion processes in the aerated landfill simulation reactors.

  5. A large volume cell for in situ neutron diffraction studies of hydrothermal crystallizations.

    PubMed

    Xia, Fang; Qian, Gujie; Brugger, Joël; Studer, Andrew; Olsen, Scott; Pring, Allan

    2010-10-01

    A hydrothermal cell with 320 ml internal volume has been designed and constructed for in situ neutron diffraction studies of hydrothermal crystallizations. The cell design adopts a dumbbell configuration assembled with standard commercial stainless steel components and a zero-scattering Ti-Zr alloy sample compartment. The fluid movement and heat transfer are simply driven by natural convection due to the natural temperature gradient along the fluid path, so that the temperature at the sample compartment can be stably sustained by heating the fluid in the bottom fluid reservoir. The cell can operate at temperatures up to 300 °C and pressures up to 90 bars and is suitable for studying reactions requiring a large volume of hydrothermal fluid to damp out the negative effect from the change of fluid composition during the course of the reactions. The capability of the cell was demonstrated by a hydrothermal phase transformation investigation from leucite (KAlSi(2)O(6)) to analcime (NaAlSi(2)O(6)⋅H(2)O) at 210 °C on the high intensity powder diffractometer Wombat in ANSTO. The kinetics of the transformation has been resolved by collecting diffraction patterns every 10 min followed by Rietveld quantitative phase analysis. The classical Avrami/Arrhenius analysis gives an activation energy of 82.3±1.1 kJ  mol(-1). Estimations of the reaction rate under natural environments by extrapolations agree well with petrological observations.

  6. A large volume cell for in situ neutron diffraction studies of hydrothermal crystallizations

    NASA Astrophysics Data System (ADS)

    Xia, Fang; Qian, Gujie; Brugger, Joël; Studer, Andrew; Olsen, Scott; Pring, Allan

    2010-10-01

    A hydrothermal cell with 320 ml internal volume has been designed and constructed for in situ neutron diffraction studies of hydrothermal crystallizations. The cell design adopts a dumbbell configuration assembled with standard commercial stainless steel components and a zero-scattering Ti-Zr alloy sample compartment. The fluid movement and heat transfer are simply driven by natural convection due to the natural temperature gradient along the fluid path, so that the temperature at the sample compartment can be stably sustained by heating the fluid in the bottom fluid reservoir. The cell can operate at temperatures up to 300 °C and pressures up to 90 bars and is suitable for studying reactions requiring a large volume of hydrothermal fluid to damp out the negative effect from the change of fluid composition during the course of the reactions. The capability of the cell was demonstrated by a hydrothermal phase transformation investigation from leucite (KAlSi2O6) to analcime (NaAlSi2O6ṡH2O) at 210 °C on the high intensity powder diffractometer Wombat in ANSTO. The kinetics of the transformation has been resolved by collecting diffraction patterns every 10 min followed by Rietveld quantitative phase analysis. The classical Avrami/Arrhenius analysis gives an activation energy of 82.3±1.1 kJ mol-1. Estimations of the reaction rate under natural environments by extrapolations agree well with petrological observations.

  7. In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction

    SciTech Connect

    Álvarez-Pinazo, G.; Cuesta, A.; García-Maté, M.; Santacruz, I.; Losilla, E.R.; Fauth, F.; Aranda, M.A.G.; De la Torre, A.G.

    2014-02-15

    Eco-friendly belite calcium sulfoaluminate (BCSA) cement hydration behavior is not yet well understood. Here, we report an in-situ synchrotron X-ray powder diffraction study for the first hours of hydration of BCSA cements. Rietveld quantitative phase analysis has been used to establish the degree of reaction (α). The hydration of a mixture of ye'elimite and gypsum revealed that ettringite formation (α ∼ 70% at 50 h) is limited by ye'elimite dissolution. Two laboratory-prepared BCSA cements were also studied: non-active-BCSA and active-BCSA cements, with β- and α′{sub H}-belite as main phases, respectively. Ye'elimite, in the non-active-BCSA system, dissolves at higher pace (α ∼ 25% at 1 h) than in the active-BCSA one (α ∼ 10% at 1 h), with differences in the crystallization of ettringite (α ∼ 30% and α ∼ 5%, respectively). This behavior has strongly affected subsequent belite and ferrite reactivities, yielding stratlingite and other layered phases in non-active-BCSA. The dissolution and crystallization processes are reported and discussed in detail. -- Highlights: •Belite calcium sulfoaluminate cements early hydration mechanism has been determined. •Belite hydration strongly depends on availability of aluminum hydroxide. •Orthorhombic ye’elimite dissolved at a higher pace than cubic one. •Ye’elimite larger reaction degree yields stratlingite formation by belite reaction. •Rietveld method quantified gypsum, anhydrite and bassanite dissolution rates.

  8. Postharvest ripening study of sweet lime (Citrus limettioides) in situ by volume-localized NMR spectroscopy.

    PubMed

    Banerjee, Abhishek; George, Christy; Bharathwaj, Sathyamoorthy; Chandrakumar, Narayanan

    2009-02-25

    Spatially resolved NMR--especially volume-localized spectroscopy (VLS)is useful in various fields including clinical diagnosis, process monitoring, etc. VLS carries high significance because of its ability to identify molecular species and hence track molecular events. This paper reports the application of VLS at 200 MHz to study the postharvest ripening of sweet lime ( Citrus limettioides ) in situ, including a comparative study of normal and acetylene-mediated ripening. Localization to a cubic voxel of 64 microL was achieved with point-resolved spectroscopy (PRESS). Glucose, sucrose, fructose, and citric acid are found to be among the main constituents in the fruit. In the natural process, the sugar to acid ratio increases with ripening. Ethanol generation is seen to occur at a faster rate in acetylene-mediated ripening. Whereas NMR imaging experiments including parametric imaging (e.g., T(1) or T(2) maps) may be employed for "macro" monitoring of processes such as these, this work demonstrates that the molecular imprint of the process may be tracked noninvasively by VLS.

  9. In Situ Biological Contamination Studies of the Moon: Implications for Planetary Protection and Life Detection Missions

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Dworkin, Jason P.; Lupisella, Mark; Williams, David R.; Kminek, Gerhard; Rummel, John D.

    2010-01-01

    NASA and ESA have outlined visions for solar system exploration that will include a series of lunar robotic precursor missions to prepare for, and support a human return to the Moan, and future human exploration of Mars and other destinations, including possibly asteroids. One of the guiding principles for exploration is to pursue compelling scientific questions about the origin and evolution of life. The search for life on objects such as Mars will require careful operations, and that all systems be sufficiently cleaned and sterilized prior to launch to ensure that the scientific integrity of extraterrestrial samples is not jeopardized by terrestrial organic contamination. Under the Committee on Space Research's (COSPAR's) current planetary protection policy for the Moon, no sterilization procedures are required for outbound lunar spacecraft, nor is there a different planetary protection category for human missions, although preliminary C SPAR policy guidelines for human missions to Mars have been developed. Future in situ investigations of a variety of locations on the Moon by highly sensitive instruments designed to search for biologically derived organic compounds would help assess the contamination of the Moon by lunar spacecraft. These studies could also provide valuable "ground truth" data for Mars sample return missions and help define planetary protection requirements for future Mars bound spacecraft carrying life detection experiments. In addition, studies of the impact of terrestrial contamination of the lunar surface by the Apollo astronauts could provide valuable data to help refine future: Mars surface exploration plans for a human mission to Mars.

  10. In Situ Biological Contamination Studies of the Moon: Implications for Planetary Protection and Life Detection Missions

    NASA Astrophysics Data System (ADS)

    Glavin, Daniel P.; Dworkin, Jason P.; Lupisella, Mark; Williams, David R.; Kminek, Gerhard; Rummel, John D.

    2010-12-01

    NASA and ESA have outlined visions for solar system exploration that will include a series of lunar robotic precursor missions to prepare for, and support a human return to the Moon, and future human exploration of Mars and other destinations, including possibly asteroids. One of the guiding principles for exploration is to pursue compelling scientific questions about the origin and evolution of life. The search for life on objects such as Mars will require careful operations, and that all systems be sufficiently cleaned and sterilized prior to launch to ensure that the scientific integrity of extraterrestrial samples is not jeopardized by terrestrial organic contamination. Under the Committee on Space Research's (COSPAR's) current planetary protection policy for the Moon, no sterilization procedures are required for outbound lunar spacecraft, nor is there a different planetary protection category for human missions, although preliminary COSPAR policy guidelines for human missions to Mars have been developed. Future in situ investigations of a variety of locations on the Moon by highly sensitive instruments designed to search for biologically derived organic compounds would help assess the contamination of the Moon by lunar spacecraft. These studies could also provide valuable "ground truth" data for Mars sample return missions and help define planetary protection requirements for future Mars bound spacecraft carrying life detection experiments. In addition, studies of the impact of terrestrial contamination of the lunar surface by the Apollo astronauts could provide valuable data to help refine future Mars surface exploration plans for a human mission to Mars.

  11. In situ synchrotron study of electromigration induced grain rotations in Sn solder joints

    DOE PAGES

    Shen, Hao; Zhu, Wenxin; Li, Yao; ...

    2016-04-18

    In this paper we report an in situ study of the early stage of microstructure evolution induced by electromigration in a Pb-free β-Sn based solder joint by synchrotron polychromatic X-ray microdiffraction. With this technique, crystal orientation evolution is monitored at intragranular levels with high spatial and angular resolution. During the entire experiment, no crystal growth is detected, and rigid grain rotation is observed only in the two grains within the current crowding region, where high density and divergence of electric current occur. Theoretical calculation indicates that the trend of electrical resistance drop still holds under the present conditions in themore » grain with high electrical resistivity, while the other grain with low resistivity reorients to align its a-axis more parallel with the ones of its neighboring grains. A detailed study of dislocation densities and subgrain boundaries suggests that grain rotation in β-Sn, unlike grain rotation in high melting temperature metals which undergo displacive deformation, is accomplished via diffusional process mainly, due to the high homologous temperature.« less

  12. In situ synchrotron study of electromigration induced grain rotations in Sn solder joints

    SciTech Connect

    Shen, Hao; Zhu, Wenxin; Li, Yao; Tamura, Nobumichi; Chen, Kai

    2016-04-18

    In this paper we report an in situ study of the early stage of microstructure evolution induced by electromigration in a Pb-free β-Sn based solder joint by synchrotron polychromatic X-ray microdiffraction. With this technique, crystal orientation evolution is monitored at intragranular levels with high spatial and angular resolution. During the entire experiment, no crystal growth is detected, and rigid grain rotation is observed only in the two grains within the current crowding region, where high density and divergence of electric current occur. Theoretical calculation indicates that the trend of electrical resistance drop still holds under the present conditions in the grain with high electrical resistivity, while the other grain with low resistivity reorients to align its a-axis more parallel with the ones of its neighboring grains. A detailed study of dislocation densities and subgrain boundaries suggests that grain rotation in β-Sn, unlike grain rotation in high melting temperature metals which undergo displacive deformation, is accomplished via diffusional process mainly, due to the high homologous temperature.

  13. The use of in situ benthic chambers to study the fate of oil in sublittoral sediments

    NASA Astrophysics Data System (ADS)

    Davies, J. M.; Tibbetts, P. J. C.

    1987-02-01

    Twelve in situ benthic chambers (2·2 m in diameter) were used to study the weathering of topped crude oil coated onto a submerged marine sediment over a period of about 440 days. The bulk (⋍80%) of the oil coated onto the sediment was lost during the first 40 days from both open and closed chambers. It is suggested that this oil was lost from the sediment partly into solution (perhaps after partial oxidation) or more likely, by droplet formation associated with the workover of particles by physical and biological processes. The weathering pattern of the oil remaining on the sediment was studied for a further 400 days and showed that the alkane fraction was biodegraded more rapidly than the naphthalenes, in agreement with the results from the Amoco Cadiz oil spill (Boehm et al., 1981) and that the alkyl substituted PAH homologues were biodegraded in preference to the unsubstituted parent compound. The hopane and sterane fingerprints did not change significantly over the 440 days of exposure, thus reinforcing their usefulness as long term markers of soil spills. In general the rates of biodegradation of the various classes of compounds were similar to those observed in other locations and suggested that the polycyclic aliphatics and the PAHs are very slow to degrade and will remain in the sediment for a considerable period of time.

  14. In situ synchrotron radiation diffraction study of low carbon steel during ion nitriding

    NASA Astrophysics Data System (ADS)

    Feugeas, J. N.; Hermida, J. D.; Gomez, B. J.; Kellermann, G.; Craievich, A.

    1999-09-01

    The volume close to the surface of materials subjected to ion implantation or ion diffusion exhibits structural transformations that are usually studied by x-ray diffraction. In order to characterize the kinetic aspects of structural transformations in low carbon AISI 1010 steel during ion nitriding, an in situ synchrotron radiation diffraction study was performed. An experimental set-up, a specially designed reactor, was constructed for x-ray measurements in real time. The variation in the lattice parameter with time of the initial Fe-icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/> phase was attributed to the heating effect produced by the action of an electric discharge during the first stages of the process. The analysis of the x-ray diffraction patterns indicates the formation of several iron nitrides. The Fe3N phase exhibits a progressive decrease in the interplanar distances, which is clearly a different behaviour with respect to the other observed phases, even considering a phase with nearly the same stoichiometry.

  15. In situ synchrotron study of electromigration induced grain rotations in Sn solder joints

    PubMed Central

    Shen, Hao; Zhu, Wenxin; Li, Yao; Tamura, Nobumichi; Chen, Kai

    2016-01-01

    Here we report an in situ study of the early stage of microstructure evolution induced by electromigration in a Pb-free β-Sn based solder joint by synchrotron polychromatic X-ray microdiffraction. With this technique, crystal orientation evolution is monitored at intragranular levels with high spatial and angular resolution. During the entire experiment, no crystal growth is detected, and rigid grain rotation is observed only in the two grains within the current crowding region, where high density and divergence of electric current occur. Theoretical calculation indicates that the trend of electrical resistance drop still holds under the present conditions in the grain with high electrical resistivity, while the other grain with low resistivity reorients to align its a-axis more parallel with the ones of its neighboring grains. A detailed study of dislocation densities and subgrain boundaries suggests that grain rotation in β-Sn, unlike grain rotation in high melting temperature metals which undergo displacive deformation, is accomplished via diffusional process mainly, due to the high homologous temperature. PMID:27086863

  16. Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons

    SciTech Connect

    Bodek, Arie

    2015-09-01

    We present preliminary results on an experimental study of the nuclear modification of the longitudinal (σL) and transverse (σT) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= σLT for nuclei (RA) and for deuterium (RD) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, RA < RD.

  17. The structure function as a metric for roughness and figure

    NASA Astrophysics Data System (ADS)

    Parks, Robert E.; Tuell, Michael T.

    2016-09-01

    As optical designs become more sophisticated and incorporate aspheric and free form surfaces, the need to specify limits on mid-spatial frequency manufacturing errors becomes more critical, particularly as we better understand the effects of these errors on image quality. While there already exist methods based on Fourier analysis to specify these errors in most commercial interferometry software, the method of calculation and the power spectral density (PSD) results remain obscure to many in the optical design and manufacturing field. We suggest that the structure functions (SF) contains the same information as in the Fourier based PSD but in a way that is much more transparent to analysis, interpretation and application as a specification. The units of measure are more familiar and the concept behind the analysis is simpler to understand. Further, the information contained in the structure function (or PSD) allows a complete specification of an optical surface from the finest measurable detail of roughness to the overall figure. We discuss the origin of the structure function in the field of astronomy to describe the effects of air turbulence on image quality, the simple mathematical definition of the structure function and its easy means of calculation and how its results should be scaled depending on the location of the optical surface in a system from pupil to image plane. Finally, we give an example of how to write a specification of an optical surface using the structure function.

  18. Neurolinguistics: Structure, Function, and Connectivity in the Bilingual Brain.

    PubMed

    Wong, Becky; Yin, Bin; O'Brien, Beth

    2016-01-01

    Advances in neuroimaging techniques and analytic methods have led to a proliferation of studies investigating the impact of bilingualism on the cognitive and brain systems in humans. Lately, these findings have attracted much interest and debate in the field, leading to a number of recent commentaries and reviews. Here, we contribute to the ongoing discussion by compiling and interpreting the plethora of findings that relate to the structural, functional, and connective changes in the brain that ensue from bilingualism. In doing so, we integrate theoretical models and empirical findings from linguistics, cognitive/developmental psychology, and neuroscience to examine the following issues: (1) whether the language neural network is different for first (dominant) versus second (nondominant) language processing; (2) the effects of bilinguals' executive functioning on the structure and function of the "universal" language neural network; (3) the differential effects of bilingualism on phonological, lexical-semantic, and syntactic aspects of language processing on the brain; and (4) the effects of age of acquisition and proficiency of the user's second language in the bilingual brain, and how these have implications for future research in neurolinguistics.

  19. Structure/Function/Dynamics of Photosystem II Plastoquinone Binding Sites

    PubMed Central

    Lambreva, Maya D.; Russo, Daniela; Polticelli, Fabio; Scognamiglio, Viviana; Antonacci, Amina; Zobnina, Veranika; Campi, Gaetano; Rea, Giuseppina

    2014-01-01

    Photosystem II (PSII) continuously attracts the attention of researchers aiming to unravel the riddle of its functioning and efficiency fundamental for all life on Earth. Besides, an increasing number of biotechnological applications have been envisaged exploiting and mimicking the unique properties of this macromolecular pigment-protein complex. The PSII organization and working principles have inspired the design of electrochemical water splitting schemes and charge separating triads in energy storage systems as well as biochips and sensors for environmental, agricultural and industrial screening of toxic compounds. An intriguing opportunity is the development of sensor devices, exploiting native or manipulated PSII complexes or ad hoc synthesized polypeptides mimicking the PSII reaction centre proteins as bio-sensing elements. This review offers a concise overview of the recent improvements in the understanding of structure and function of PSII donor side, with focus on the interactions of the plastoquinone cofactors with the surrounding environment and operational features. Furthermore, studies focused on photosynthetic proteins structure/function/dynamics and computational analyses aimed at rational design of high-quality bio-recognition elements in biosensor devices are discussed. PMID:24678671

  20. Neurolinguistics: Structure, Function, and Connectivity in the Bilingual Brain

    PubMed Central

    Wong, Becky; Yin, Bin; O'Brien, Beth

    2016-01-01

    Advances in neuroimaging techniques and analytic methods have led to a proliferation of studies investigating the impact of bilingualism on the cognitive and brain systems in humans. Lately, these findings have attracted much interest and debate in the field, leading to a number of recent commentaries and reviews. Here, we contribute to the ongoing discussion by compiling and interpreting the plethora of findings that relate to the structural, functional, and connective changes in the brain that ensue from bilingualism. In doing so, we integrate theoretical models and empirical findings from linguistics, cognitive/developmental psychology, and neuroscience to examine the following issues: (1) whether the language neural network is different for first (dominant) versus second (nondominant) language processing; (2) the effects of bilinguals' executive functioning on the structure and function of the “universal” language neural network; (3) the differential effects of bilingualism on phonological, lexical-semantic, and syntactic aspects of language processing on the brain; and (4) the effects of age of acquisition and proficiency of the user's second language in the bilingual brain, and how these have implications for future research in neurolinguistics. PMID:26881224

  1. Nucleome Analysis Reveals Structure-function Relationships for Colon Cancer.

    PubMed

    Seaman, Laura; Chen, Haiming; Brown, Markus; Wangsa, Darawalee; Patterson, Geoff; Camps, Jordi; Omenn, Gilbert S; Ried, Thomas; Rajapakse, Indika

    2017-03-03

    Chromosomal translocations and aneuploidy are hallmarks of cancer genomes; however, the impact of these aberrations on the nucleome (i.e., nuclear structure and gene expression) are not yet understood. Here, the nucleome of the colorectal cancer cell line HT-29 was analyzed using chromosome conformation capture (Hi-C) to study genome structure, complemented by RNA sequencing (RNA-seq) to determine consequent changes in genome function. Importantly, translocations and copy number changes were identified at high resolution from Hi-C data and the structure-function relationships present in normal cells were maintained in cancer. In addition, a new copy number-based normalization method for Hi-C data was developed to analyze the effect of chromosomal aberrations on local chromatin structure. The data demonstrate that at the site of translocations the correlation between chromatin organization and gene expression increases; thus, chromatin accessibility more directly reflects transcription. Additionally, the homogeneously staining region of chromosome band 8q24 of HT-29, which includes the MYC oncogene, interacts with various loci throughout the genome and is composed of open chromatin. The methods, described herein, can be applied to the assessment of the nucleome in other cell types with chromosomal aberrations.

  2. Scaling behavior in turbulent Rayleigh-Bénard convection revealed by conditional structure functions.

    PubMed

    Ching, Emily S C; Tsang, Yue-Kin; Fok, T N; He, Xiaozhou; Tong, Penger

    2013-01-01

    We show that the nature of the scaling behavior can be revealed by studying the conditional structure functions evaluated at given values of the locally averaged thermal dissipation rate. These conditional structure functions have power-law dependence on the value of the locally averaged thermal dissipation rate, and such dependence for the Bolgiano-Obukhov scaling is different from the other scaling behaviors. Our analysis of experimental measurements verifies the power-law dependence and reveals the Bolgiano-Obukhov scaling behavior at the center of the bottom plate of the convection cell.

  3. In situ studies of surface of NiFe2O4 catalyst during complete oxidation of methane

    DOE PAGES

    Zhang, Shiran; Shan, Junjun; Nie, Longhui; ...

    2015-12-21

    Here, NiFe2O4 with an inverse spinel structure exhibits high activity for a complete oxidation of methane at 400 °C–425 °C and a higher temperature. The surface of the catalyst and its adsorbates were well characterized with ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and in situ infrared spectroscopy (IR). In situ studies of the surface of NiFe2O4 using AP-XPS suggest the formation of methoxy-like and formate-like intermediates at a temperature lower than 200 °C, supported by the observed vibrational signatures in in situ IR studies. Evolutions of C1s photoemission features and the nominal atomic ratios of C/(Ni + Fe) of themore » catalyst surface suggest that the formate-like intermediate is transformed to product molecules CO2 and H2O in the temperature range of 250–300 °C. In situ studies suggest the formation of a spectator, – Olattice – CH2 – Olattice –. It strongly bonds to surface through C–O bonds and cannot be activated even at 400 °C.« less

  4. In situ studies of surface of NiFe2O4 catalyst during complete oxidation of methane

    NASA Astrophysics Data System (ADS)

    Zhang, Shiran; Shan, Junjun; Nie, Longhui; Nguyen, Luan; Wu, Zili; Tao, Franklin (Feng)

    2016-06-01

    NiFe2O4 with an inverse spinel structure exhibits high activity for a complete oxidation of methane at 400 °C-425 °C and a higher temperature. The surface of the catalyst and its adsorbates were well characterized with ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and in situ infrared spectroscopy (IR). In situ studies of the surface of NiFe2O4 using AP-XPS suggest the formation of methoxy-like and formate-like intermediates at a temperature lower than 200 °C, supported by the observed vibrational signatures in in situ IR studies. Evolutions of C1s photoemission features and the nominal atomic ratios of C/(Ni + Fe) of the catalyst surface suggest that the formate-like intermediate is transformed to product molecules CO2 and H2O in the temperature range of 250-300 °C. In situ studies suggest the formation of a spectator, - Olatticesbnd CH2sbnd Olattice -. It strongly bonds to surface through Csbnd O bonds and cannot be activated even at 400 °C.

  5. I Situ Electrochemical Scanning Tunneling Microscopy Study of Dealloying and Stress Corrosion Cracking of Copper - Alloys.

    NASA Astrophysics Data System (ADS)

    Chen, Jin-Syung Fred

    The mechanism of stress corrosion cracking (SCC) of Cu-30Au in 0.6 M NaCl was investigated by a series of experiments, in which samples were dealloyed (i.e., selective removal of copper atoms) by potentiostatic anodic polarization at zero applied stress (i) for varying lengths of time (10 seconds to 30 minutes) and then impact bent, and (ii) for 30 minutes followed by a period of time (5 seconds to 10 minutes) at the open circuit potential and then impact bent. The results indicate that dealloying at zero applied stress produces a surface porous layer that is capable, for a brief period of time (<= ~ 15 seconds), of inducing intergranular cleavage failure of the normally ductile FCC substrate. However, for time >15 seconds at open circuit potential, aging or coarsening reverses the ability of the surface layer to induce cleavage. In addition, samples were dealloyed and simultaneously stressed at various nominal values. At low values of applied stress, failure occurred by brittle intergranular cracking (IGSCC); and at high values of stress, failure occurred by brittle transgranular cracking (TGSCC). The results indicate that the mechanism of IGSCC is identical to that of TGSCC and can best be described by a modification of the "film-induced cleavage" model. The implication of the aging phenomenon to the film-induced cleavage model of stress corrosion cracking is also discussed. An electrochemical scanning tunneling microscope (ESTM) was built and used to study the in-situ dealloying process of thin-film Cu-Au alloys. Thin-films of Cu-75 at%Au alloy were prepared by thermal evaporation of the bulk alloy and deposition of the vapor onto heated mica. The surface structure of the thin film thus grown consists of terrace of well defined (111) planes separated by atomic height steps. The results from in-situ ESTM indicate that if applied potentials were lower than the critical potential (E_{rm c}), dissolution of Cu preferentially occurred at the low coordination sites

  6. The high - low-p clinoenstatite transition: in situ xrd and ultrasonic study

    NASA Astrophysics Data System (ADS)

    Müller, H. J.; Wunder, B.; Lathe, C.; Schilling, F. R.

    2003-04-01

    Using single-crystal X-ray diffraction analyses in a diamond anvil cell Angel et al. (1992) published the transformation of MgSiO_3 from LCEn to a C2/c-polymorph (HCEn) at around 5.5 - 8.0 GPa and room-T (RT)conditions. This LCEn - HCEn-transition is not quenchable. However, the knowledge of the exact phase boundary positions for the MgSiO_3-transitions is essential as pyroxene is an important component of the Earth's mantle and will significantly influence elastic properties (e.g. v_p, v_s) of the mantle. We determined the HCEn - LCEn-transition by in-situ XRD experiments under high P, T using the multi-anvil appar atus MAX80 at the synchrotron facility HASYLAB, Hamburg. Our preliminary results only represent the minimum P-conditions of the HCEn - LCEn phase boundary, which is approximated by equation P (GPa) = 0.0021T (/C) + 6.06. Nevertheless, our results are in good agreement to data published by Angel & Hugh-Jones (1994). The invariant point defined by the intersection of the HCEn - LCEn equilibrium determined within this study and the OEn - LCEn reaction after Angel &Hugh-Jones (1994) lies at about 7.9 GPa and 875/C. This is in contrast to earlier experimental results of Kanzaki (1991) and Ulmer &Stalder (2001). The samples for the ultrasonic interferometry experiments were prepared by hot-isostatic pressing also using the MAX80. Adjacent XRD ruled out any phase transition during the hip-process. For the ultrasonic measurements one of the six anvils of MAX80 were exchanged by an anvil equipped with lithium niobate p- and s-wave transducers of 33.3 MHz natural frequency (Mueller et al., 2002). Corresponding to the XRD experiments HCEn was formed by increasing the pressure at RT. The velocities of elastic compressional and shear waves were measured under in situ conditions using the classical digital sweep technique. After the phase transition to LCEn as a result of rising the temperature at given pressure the measurements were repeated. The newly developed

  7. First in situ TOF-PET study using digital photon counters for proton range verification

    NASA Astrophysics Data System (ADS)

    Cambraia Lopes, P.; Bauer, J.; Salomon, A.; Rinaldi, I.; Tabacchini, V.; Tessonnier, T.; Crespo, P.; Parodi, K.; Schaart, D. R.

    2016-08-01

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong 15O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  108 protons s-1, and 1010 total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results also

  8. First in situ TOF-PET study using digital photon counters for proton range verification.

    PubMed

    Cambraia Lopes, P; Bauer, J; Salomon, A; Rinaldi, I; Tabacchini, V; Tessonnier, T; Crespo, P; Parodi, K; Schaart, D R

    2016-08-21

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong (15)O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  10(8) protons s(-1), and 10(10) total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results

  9. Photosynthetic activity, photoprotection and photoinhibition in intertidal microphytobenthos as studied in situ using variable chlorophyll fluorescence

    NASA Astrophysics Data System (ADS)

    Serôdio, João; Vieira, Sónia; Cruz, Sónia

    2008-06-01

    The photosynthetic activity of microphytobenthos biofilms was studied in situ on an intertidal mudflat of the Ria de Aveiro, Portugal. Time series of physical variables characterizing the microenvironment at the sediment photic zone (incident solar irradiance, temperature, salinity), photophysiological parameters and productive biomass of undisturbed microalgal assemblages were measured during daytime low-tide periods along one spring-neap tidal cycle, with the objective of (1) characterizing the short-term variability in photosynthetic activity in situ, (2) relating it with the changing environmental conditions and (3) with the operation of physiologically (xanthophyll cycle) and behaviorally (vertical migration) based photoprotective processes, and (4) assessing the occurrence of photoinhibition. Pulse Amplitude Modulated (PAM) fluorometry was applied to measure photosynthetic activity (the effective and maximum quantum yield of photosystem II, Δ F/ Fm' and Fv/ Fm; the photosynthesis index EFY; rapid light-response curves (RLC)), the photoprotective operation of the xanthophyll cycle and photoinhibition (non-photochemical quenching, NPQ; quantum efficiency of open RCs, Fv'/ Fm'), and vertical migration (productive biomass, Fo). The photosynthetic activity was found to be strongly affected by the cumulative light dose received during the morning low-tide periods. The fluorescence indices Δ F/ Fm', EFY, Fv'/ Fm' and RLC parameters were more depressed under high irradiances when clear sky was present during the morning low tide than when foggy conditions reduced the light dose received during a comparable period. Productive biomass exhibited maximum values in the first hours of the morning, followed by a steep decrease when irradiance reached moderate levels, due to the downward migration of the microalgae. This photophobic migratory response appeared to display a photoprotective role, allowing Δ F/ Fm' to remain near optimum values until irradiance reached

  10. Studying the vertical aerosol extinction coefficient by comparing in situ airborne data and elastic backscatter lidar

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Herrmann, Erik; Bucci, Silvia; Fierli, Federico; Cairo, Francesco; Gysel, Martin; Tillmann, Ralf; Größ, Johannes; Gobbi, Gian Paolo; Di Liberto, Luca; Di Donfrancesco, Guido; Wiedensohler, Alfred; Weingartner, Ernest; Virtanen, Annele; Mentel, Thomas F.; Baltensperger, Urs

    2016-04-01

    Vertical profiles of aerosol particle optical properties were explored in a case study near the San Pietro Capofiume (SPC) ground station during the PEGASOS Po Valley campaign in the summer of 2012. A Zeppelin NT airship was employed to investigate the effect of the dynamics of the planetary boundary layer at altitudes between ˜ 50 and 800 m above ground. Determined properties included the aerosol particle size distribution, the hygroscopic growth factor, the effective index of refraction and the light absorption coefficient. The first three parameters were used to retrieve the light scattering coefficient. Simultaneously, direct measurements of both the scattering and absorption coefficient were carried out at the SPC ground station. Additionally, a single wavelength polarization diversity elastic lidar system provided estimates of aerosol extinction coefficients using the Klett method to accomplish the inversion of the signal, for a vertically resolved comparison between in situ and remote-sensing results. Note, however, that the comparison was for the most part done in the altitude range where the overlap function is incomplete and accordingly uncertainties are larger. First, the airborne results at low altitudes were validated with the ground measurements. Agreement within approximately ±25 and ±20 % was found for the dry scattering and absorption coefficient, respectively. The single scattering albedo, ranged between 0.83 and 0.95, indicating the importance of the absorbing particles in the Po Valley region. A clear layering of the atmosphere was observed during the beginning of the flight (until ˜ 10:00 LT - local time) before the mixing layer (ML) was fully developed. Highest extinction coefficients were found at low altitudes, in the new ML, while values in the residual layer, which could be probed at the beginning of the flight at elevated altitudes, were lower. At the end of the flight (after ˜ 12:00 LT) the ML was fully developed, resulting in

  11. Neutron (3He) Spin Structure Functions at Low Q^2

    SciTech Connect

    Vincent Sulkosky

    2009-07-01

    Experiment E97-110 was performed at the Thomas Jefferson National Accelerator Facility to provide a precise measurement of the $^{3}$He spin structure functions at low $Q^{2}$ from 0.02 to 0.3~[GeV$/c$]$^{2}$. A longitudinally-polarized electron beam was scattered from a longitudinally or transversely polarized $^{3}$He target. From these data, we have extracted moments of the neutron and $^{3}$He spin structure functions at very low momentum transfers. These data allow us to make a benchmark check of Chiral Perturbation Theory calculations in a region where they are expected to be valid. In these proceedings, the experimental details are discussed and preliminary results on the first moments of the $g_1\\left(x,Q^{2}\\right)$ and $g_2\\left(x,Q^{2}\\right)$ structure functions are presented.

  12. In situ study of heavy ion induced radiation damage in NF616 (P92) alloy

    NASA Astrophysics Data System (ADS)

    Topbasi, Cem; Motta, Arthur T.; Kirk, Mark A.

    2012-06-01

    NF616 is a nominal 9Cr ferritic-martensitic steel that is amongst the primary candidates for cladding and duct applications in the Sodium-Cooled Fast Reactor, one of the Generation IV nuclear energy systems. In this study, an in situ investigation of the microstructure evolution in NF616 under heavy ion irradiation has been conducted. NF616 was irradiated to 8.4 dpa at 50 K and to 7.6 dpa at 473 K with 1 MeV Kr ions. Nano-sized defects first appeared as white dots in dark-field TEM images and their areal density increased until saturation (˜6 dpa). Dynamic observations at 50 K and 473 K showed appearance and disappearance of TEM-visible defect clusters under irradiation that continued above saturation dose. Quantitative analysis showed no significant change in the average size (˜3-4 nm) and distribution of defect clusters with increasing dose at 50 K and 473 K. These results indicate a cascade-driven process of microstructure evolution under irradiation in these alloys that involves both the formation of TEM-visible defect clusters by various degrees of cascade overlap and cascade induced defect cluster elimination. According to this mechanism, saturation of defect cluster density is reached when the rate of defect cluster formation by overlap is equal to the rate of cluster elimination during irradiation.

  13. Aging behavior of lithium iron phosphate based 18650-type cells studied by in situ neutron diffraction

    NASA Astrophysics Data System (ADS)

    Paul, Neelima; Wandt, Johannes; Seidlmayer, Stefan; Schebesta, Sebastian; Mühlbauer, Martin J.; Dolotko, Oleksandr; Gasteiger, Hubert A.; Gilles, Ralph

    2017-03-01

    The aging behavior of commercially produced 18650-type Li-ion cells consisting of a lithium iron phosphate (LFP) based cathode and a graphite anode based on either mesocarbon microbeads (MCMB) or needle coke (NC) is studied by in situ neutron diffraction and standard electrochemical techniques. While the MCMB cells showed an excellent cycle life with only 8% relative capacity loss (i.e., referenced to the capacity after formation) after 4750 cycles and showed no capacity loss on storage for two years, the needle coke cells suffered a 23% relative capacity loss after cycling and a 11% loss after storage. Based on a combination of neutron diffraction and electrochemical characterization, it is shown that the entire capacity loss for both cell types is dominated by the loss of active lithium; no other aging mechanisms like structural degradation of anode or cathode active materials or deactivation of active material could be found, highlighting the high structural stability of the active material and the excellent quality of the investigated cells.

  14. In situ speciation studies of copper in the electroplating sludge under an electric field.

    PubMed

    Liu, S-H; Wang, H Paul

    2004-08-01

    Speciation of copper in the electrokinetic treatments of an industrial sludge was studied by in situ extended X-ray absorption fine structural (EXAFS) and X-ray absorption near-edge structural (XANES) spectroscopies in the present work. The least-square fits (LSF) of the XANES spectra indicated that the main copper species in the sludge were Cu(NO)(3) (82%) and adsorbed copper (Cu/SiO(2)) (17%). Copper in the sludge possessed a Cu-O bond distance of 1.97A with a coordination number (CN) of 3.8. In the second shells, the bond distance of Cu-(O)-Si was 3.03A with a CN of 1.5. Most of Cu/SiO(2) was dissolved in the aqueous phase since little Cu-(O)-Si species in the sludge was found after 180 min of the electrokinetic treatments. About 69% of total Cu(II) was dissolved into the aqueous phase and 51% of which was migrated to the cathode under the electric field (5V cm(-1)) for 180 min.

  15. In situ Raman spectroscopic study of marble capitals in the Alhambra monumental ensemble

    NASA Astrophysics Data System (ADS)

    Arjonilla, Paz; Domínguez-Vidal, Ana; de la Torre López, María José; Rubio-Domene, Ramón; Ayora-Cañada, María José

    2016-12-01

    The marble capitals of five different sites in the Alhambra complex (Granada, Spain), namely the Mexuar, the Hall of the Abencerrages, the Hall of the Kings, the Court of the Myrtles and the Court of the Main Canal, have been investigated. The decoration of the capitals exhibits mainly blue, red, black and gilding motifs with different states of conservation. The work has been carried out in situ by means of a portable Raman micro-spectrometer with an excitation laser of 785 nm. In addition to preserving the artwork with a non-invasive study, the on-site investigation gives a more representative knowledge of the art objects because the measurements are not limited to the samples that can be taken (few and small). The obtained Raman spectra were of good quality despite challenging adverse conditions out of the laboratory. Cinnabar, minium, carbon black, natural lapis lazuli and azurite were the main pigments found. Synthetic ultramarine blue was also detected in a capital as a result of a modern restoration. Degradation products as tin oxide in the gildings and weddellite in the preparation layers were also identified. All the results together with a careful visual inspection can be combined to elucidate the different execution techniques employed to apply the pigments on the marble substrate of the capitals in the Nasrid and Christian periods.

  16. Slip-System-Related Dislocation Study from In-Situ Neutron Measurements

    SciTech Connect

    Huang, E-Wen; Barabash, Rozaliya; Jia, Nan; Wang, Yandong; Ice, Gene E; Clausen, Bjorn; Horton Jr, Joe A; Liaw, Peter K

    2008-01-01

    A combined experimental/computational approach is employed to study slip-system-related dislocation-substructure formation during uniaxial tension of a single-phase, face-centered-cubic (fcc), nickel-based alloy. In-situ neutron-diffraction measurements were conducted to monitor the peak-intensity, peak-position, and peak-broadening evolution during a displacement-controlled, monotonic-tension experiment at room temperature. The measured lattice-strain evolution and the macrostress/macrostrain curves were used to obtain the material parameters required for simulating the texture development by a visco-plastic self-consistent (VPSC) model. The simulated texture compared favorably with experimentally-determined texture results over a range of 0 to 30 pct engineering strain. The grain-orientation-dependent input into the Debye-intensity ring was considered. Grains favorably oriented relative to the two detector banks in the geometry of the neutron experiment were indicated. For the favorably oriented grains, the simulated slip-system activity was used to calculate the slip-system-dependent, dislocation-contrast factor. The combination of the calculated contrast factor with the experimentally-measured peak broadening allows the assessment of the parameters of the dislocation arrangement within the specifically oriented grains, which has a quantitative agreement with the transmission-electron-microscopy results.

  17. Underpotential deposition of Cd on Ag(1 1 1): an in situ STM study

    NASA Astrophysics Data System (ADS)

    García, S. G.; Salinas, D. R.; Staikov, G.

    2005-02-01

    The kinetics and mechanism of Cd underpotential deposition (UPD) and involved surface alloy formation processes in the system Ag(1 1 1)/Cd 2+, SO42-, are studied by means of combined electrochemical measurements and in situ scanning tunneling microscopy (STM). The results show that the UPD process starts with a formation of an expanded (diluted) adlayer with a superlattice structure Ag(1 1 1)- (√{3}×√{19})R23.4°. In the underpotential range 50 mV < Δ E < 80 mV this adlayer transforms to a condensed close packed Cd monolayer via a first order phase transition. At long polarization times the condensed monolayer undergoes structural changes involving place exchange processes between Cd atoms and surface Ag atoms. A formation of a second Cd monolayer and a significant Ag-Cd surface alloying take place at lower underpotentials (Δ E < 50 mV). The kinetics of surface alloying are analyzed on the basis of a recently proposed diffusion model including a relatively fast initial formation of a very thin surface alloy film and a subsequent slow alloy growth controlled by solid state diffusion. The anodic dealloying results in an appearance of monatomically deep pits, which disappear quickly at relatively high underpotentials (Δ E > 550 mV) indicating a high mobility of surface Ag atoms.

  18. Gelatinolytic activity of matrix metalloproteinase in lung cancer studied using film in situ zymography stamp method.

    PubMed

    Kaji, Masahiro; Moriyama, Satoru; Sasaki, Hidefumi; Saitoh, Yushi; Kiriyama, Masanobu; Fukai, Ichiro; Yamakawa, Yosuke; Mitsui, Akira; Toyama, Tatsuya; Nemori, Ryoichi; Fujii, Yoshitaka

    2003-02-01

    In this study, we investigated activity of matrix metalloproteinase (MMP) of lung cancer by newly developed film in situ zymography (FIZ) stamp method, which allows visual localization of gelatinolytic activity within the cut surface of a tumor. We performed FIZ stamp method and conventional gelatin zymography in 39 resected specimen of lung cancer. The degree of gelatinolytic activity was scored (FIZ score) and correlated with the clinicopathological factors of the tumor. FIZ score of normal lung was very low. Lung cancer tissue had consistently higher FIZ score than the matched normal lung tissue. There were statistically significant differences in the FIZ score according to the pathological stage (P = 0.0015), nodal status (P = 0.0007) and lymphatic invasion (P = 0.0004). Direct correlation was observed between the FIZ score and MMP-2 activity (rho = 0.568, P = 0.0030) as quantitated using conventional gelatin zymography. MMP-2 may play an important role in the lymphatic invasion of lung cancer. FIZ stamp method may be a simple and useful diagnostic aid for the presence of cancer cells in the resected specimen.

  19. In Situ Study of Strain-Dependent Ion Conductivity of Stretchable Polyethylene Oxide Electrolyte

    PubMed Central

    Kelly, Taylor; Ghadi, Bahar Moradi; Berg, Sean; Ardebili, Haleh

    2016-01-01

    There is a strong need in developing stretchable batteries that can accommodate stretchable or irregularly shaped applications including medical implants, wearable devices and stretchable electronics. Stretchable solid polymer electrolytes are ideal candidates for creating fully stretchable lithium ion batteries mainly due to their mechanical and electrochemical stability, thin-film manufacturability and enhanced safety. However, the characteristics of ion conductivity of polymer electrolytes during tensile deformation are not well understood. Here, we investigate the effects of tensile strain on the ion conductivity of thin-film polyethylene oxide (PEO) through an in situ study. The results of this investigation demonstrate that both in-plane and through-plane ion conductivities of PEO undergo steady and linear growths with respect to the tensile strain. The coefficients of strain-dependent ion conductivity enhancement (CSDICE) for in-plane and through-plane conduction were found to be 28.5 and 27.2, respectively. Tensile stress-strain curves and polarization light microscopy (PLM) of the polymer electrolyte film reveal critical insights on the microstructural transformation of stretched PEO and the potential consequences on ionic conductivity. PMID:26831948

  20. Coarsening of Pd nanoparticles in an oxidizing atmosphere studied by in situ TEM

    NASA Astrophysics Data System (ADS)

    Simonsen, Søren Bredmose; Chorkendorff, Ib; Dahl, Søren; Skoglundh, Magnus; Helveg, Stig

    2016-06-01

    The coarsening of supported palladium nanoparticles in an oxidizing atmosphere was studied in situ by means of transmission electron microscopy (TEM). Specifically, the Pd nanoparticles were dispersed on a planar and amorphous Al2O3 support and were observed during the exposure to 10 mbar technical air at 650 °C. Time-resolved TEM image series reveal that the Pd nanoparticles were immobile and that a few percent of the nanoparticles grew or shrank, indicating a coarsening process mediated by the Ostwald ripening mechanism. The TEM image contrast suggests that the largest nanoparticles tended to wet the Al2O3 support to a higher degree than the smaller nanoparticles and that the distribution of projected particle sizes consequently broadens by the appearance of an asymmetric tail toward the larger particle sizes. A comparison with computer simulations based on a simple mean-field model for the Ostwald ripening process indicates that the observed change in the particle size distribution can be accounted for by wetting of the Al2O3 support by the larger Pd nanoparticles.

  1. In Situ Study of Strain-Dependent Ion Conductivity of Stretchable Polyethylene Oxide Electrolyte

    NASA Astrophysics Data System (ADS)

    Kelly, Taylor; Ghadi, Bahar Moradi; Berg, Sean; Ardebili, Haleh

    2016-02-01

    There is a strong need in developing stretchable batteries that can accommodate stretchable or irregularly shaped applications including medical implants, wearable devices and stretchable electronics. Stretchable solid polymer electrolytes are ideal candidates for creating fully stretchable lithium ion batteries mainly due to their mechanical and electrochemical stability, thin-film manufacturability and enhanced safety. However, the characteristics of ion conductivity of polymer electrolytes during tensile deformation are not well understood. Here, we investigate the effects of tensile strain on the ion conductivity of thin-film polyethylene oxide (PEO) through an in situ study. The results of this investigation demonstrate that both in-plane and through-plane ion conductivities of PEO undergo steady and linear growths with respect to the tensile strain. The coefficients of strain-dependent ion conductivity enhancement (CSDICE) for in-plane and through-plane conduction were found to be 28.5 and 27.2, respectively. Tensile stress-strain curves and polarization light microscopy (PLM) of the polymer electrolyte film reveal critical insights on the microstructural transformation of stretched PEO and the potential consequences on ionic conductivity.

  2. ARPES study of the YBCO phase diagram by in-situ K evaporation

    NASA Astrophysics Data System (ADS)

    Fournier, D.; Levy, G.; McCheyney, J. L.; Bostwick, A.; Rotenberg, E.; Hardy, W. N.; Liang, R. X.; Bonn, D. A.; Elfimov, I. S.; Damascelli, A.

    2010-03-01

    The study of the YBCO phase diagram by ARPES has become of central interest since the observation of quantum oscillations in high-magnetic field [1]. However, until recently accessing the various electronic phases by photoemission has been hampered by the so-called polar catastrophe [2]. In this work, the overdoped metal (OD, p=0.37, Tc=0), the superconducting phase (OP, Tsitu K evaporation). This reveals that the dispersion, as well as the arc topology of the low energy excitations of the normal state, are universal [3]. While no traces of an electronic reconstruction have been observed in YBCO, we are able to identify the doping value at which the Luttinger description breaks down upon underdoping.[1] N. Doiron-Leyraud et al., Nature 447, 565 (2007).[2] M. A. Hossain et al., Nat. Phys. 4, 527 (2008).[3] K. M. Shen et al., Science 307, 901 (2005).

  3. In situ Raman study of Electrochemically Intercalted Bisulfate Ions in Carbon Nanotube Bundles

    NASA Astrophysics Data System (ADS)

    Sumanasekera, G. U.; Allen, J. L.; Rao, A. M.; Fang, S. L.; Eklund, P. C.

    1998-03-01

    We have investigated the electrochemical intercalation of bisulfate ions in single-walled carbon nanotubes (SWNT) using in situ Raman spectroscopy. SWNTs pressed onto a Pt plate was used as the working electrode, a Pt wire and Ag/AgCl were used, respectively, as the counter electrode and reference electrode. Sulfuric acid (95%) was used as the electrolyte. Using Raman scattering we have observed an apparent rapid spontaneous reaction involving charge transfer between ionically bonded HSO_4^- anions and the nanotubes. This is evidenced by an instantaneous shift of the Raman-active tangential mode frequency from 1593 cm -1 to 1604 cm-1 (It was not possible to reverse this shift electrochemically to 1593 cm-1, even at the expense of large reverse bias). In forward bias, after this initial instantaneous reaction, the tangential mode frequency again upshifted from 1604 cm-1 to 1614 cm-1 linearly with external electrochemical charge Q. From the slope of ω(Q) we found in this regime, δω/δ f= 1220 cm-1 (f = holes/carbon). Upon further charging, a second regime with slope δω/δ f = 118 cm-1 was observed where the frequency upshifted from 1614 cm-1 to 1620 cm-1. The results are compared to similar studies in C_p^+HSO_4^-.xH_2SO4 graphite intercalation compounds.

  4. Belowground carbon allocation dynamics in changing environments: insights from in situ pulse labeling studies

    NASA Astrophysics Data System (ADS)

    Bahn, M.

    2012-12-01

    Belowground carbon (C) allocation is a key process in ecosystems: it plays an important role for plant C storage, fuels root metabolism and provides substrates for soil microorganisms, with strong implications for microbial community composition and activity and thus soil organic matter turnover. Belowground C allocation has been well studied in young plants and mesocosms, and as long-term patterns in ecosystems. Much less is known on the short-term dynamics of C allocation in mature plants and ecosystems, which reflect more closely the actual processes underlying observed C allocation patterns and the mechanisms determining responses to changing environmental conditions. C allocation dynamics can best be analyzed with isotopic pulse labeling experiments, which permit a tracing of recently photo-assimilated C to carbohydrate pools, microbial communities and respiratory fluxes. This overview talk will highlight the potential and limitations of in situ isotopic tracer experiments for assessing belowground C allocation dynamics in changing environments, summarize some major recent findings and point towards emerging research questions.

  5. In situ study of dynamic recrystallization and hot deformation behavior of a multiphase titanium aluminide alloy

    NASA Astrophysics Data System (ADS)

    Liss, Klaus-Dieter; Schmoelzer, Thomas; Yan, Kun; Reid, Mark; Peel, Matthew; Dippenaar, Rian; Clemens, Helmut

    2009-12-01

    Hot-compression tests were conducted in a high-energy synchrotron x-ray beam to study in situ and in real time microstructural changes in the bulk of a β-solidifying titanium aluminide alloy. The occupancy and spottiness of the diffraction rings have been evaluated in order to access grain growth and refinement, orientation relationships, subgrain formation, dynamic recovery, and dynamic recrystallization, as well as phase transformations. This method has been applied to an alloy consisting of two coexisting phases at high temperature and it was found that the bcc β-phase recrystallizes dynamically, much faster than the hcp α-phase, which deforms predominantly through crystallographic slip underpinned by a dynamic recovery process with only a small component of dynamic recrystallization. The two phases deform to a very large extent independently from each other. The rapid recrystallization dynamics of the β-phase combined with the easy and isotropic slip characteristics of the bcc structure explain the excellent deformation behavior of the material, while the presence of two phases effectively suppresses grain growth.

  6. a Study on Microstructure Characteristics of IN SITU Formed TiC Reinforced Composite Coatings

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Guo, Wei; Luo, Hui

    2012-04-01

    In situ synthesized TiC reinforced composite coating was fabricated by laser cladding of Al-Ni-Cr-C powders on titanium alloys, which can greatly improve the surface performance of the substrate. In this study, the Al-Ni-Cr-C laser-cladded composite coatings have been researched by means of X-ray diffraction, scanning electron microscope (SEM) and electron probe micro-analyzer (EPMA). There was a metallurgical combination between the Al-Ni-Cr-C laser-cladded coating and the Ti-6Al-4V substrate, and the micro-hardness of the Al-Ni-Cr-C laser-cladded coating was in the range of 1200-1450 HV0.2, which was 3-4 times higher than that of Ti-6Al-4V substrate. Furthermore, the reinforcement of theAl-Ni-Cr-C laser-cladded coating were mainly contributed to the action of the TiC, Ti3Al, Cr7C3, Al8Cr5 phases and the solution strengthening.

  7. In situ study of the goethite-hematite phase transformation by real time synchrotron powder diffraction

    SciTech Connect

    Gualtieri, A.F.; Venturelli, P.

    1999-05-01

    The temperature induced goethite-hematite phase transformation that occurs at about 250 C was studied using in situ synchrotron X-ray powder diffraction with a capillary Debye-Scherrer geometry and a translating image plate system (TIPS). This is the first time the goethite-hematite transformation has been investigated in real time. The sample was a pure, synthetic, stoichiometric goethite with 2 {micro}m long needle-shaped crystals. The microstructural characterization showed that the sample was well crystallized. The Rietveld refinement of 30 powder patterns extracted from the image in the range 25--800 C demonstrates that an intermediate phase with non-stoichiometric composition (protohematite) forms after the decomposition of goethite. The cell parameter b of goethite dramatically decreased during the phase transformation while a and c instead continued to increase. Protohematite is iron-deficient and retains residual hydrolysis for charge balance. With temperature protohematite progressively transforms into hematite. Empty layers (pores) are consequently formed about the hematite clusters. The distribution of iron vacancies was modeled in the powder patterns with stacking faults that were simulated using anisotropic broadening coefficients of the pseudo-Voigt profile function. Its disappearance with temperature was effectively followed with a decrease of the density of stacking faults.

  8. Benzalkonium runoff from roofs treated with biocide products - In situ pilot-scale study.

    PubMed

    Gromaire, M C; Van de Voorde, A; Lorgeoux, C; Chebbo, G

    2015-09-15

    Roof maintenance practices often involve the application of biocide products to fight against moss, lichens and algae. The main component of these products is benzalkonium chloride, a mixture of alkyl benzyl dimethyl ammonium chlorides with mainly C12 and C14 alkyl chain lengths, which is toxic for the aquatic environment. This paper describes, on the basis of an in-situ pilot scale study, the evolution of roof runoff contamination over a one year period following the biocide treatment of roof frames. Results show a major contamination of roof runoff immediately after treatment (from 5 to 30 mg/L), followed by an exponential decrease. 175-375 mm of cumulated rainfall is needed before the runoff concentrations become less than EC50 values for fish (280 μg/l). The residual concentration in the runoff water remains above 4 μg/L even after 640 mm of rainfall. The level of benzalkonium ions leaching depends on the roofing material, with lower concentrations and total mass leached from ceramic tiles than from concrete tiles, and on the state of the tile (new or worn out). Mass balance calculations indicate that a large part of the mass of benzalkonium compounds applied to the tiles is lost, probably due to biodegradation processes.

  9. TEM in situ deformation study of the interaction of lattice dislocations with grain boundaries in metals

    SciTech Connect

    Lee, T.C.; Robertson, I.M.; Birnbaum, H.K. )

    1990-01-01

    The passage of dislocations across grain boundaries in metals has been studied by using the in situ TEM deformation technique. A detailed analysis of the interaction of glissile matrix dislocations with grain-boundary dislocations has been performed. The results show that the dislocations piled-up at the grain boundary can: (1) be transferred directly through the grain boundary into the adjoining grain; (2) be absorbed and transformed into extrinsic grain-boundary dislocations; (3) be accommodated in the grain boundary, followed by the emission from the grain boundary of a matrix dislocation; and (4) be ejected back into their original grain. To predict which slip system is favorable for slip transfer, three criteria have been considered, namely: (1) the angle between the lines of intersection of the incoming and outgoing slip lanes with the grain boundary, this should be as small as possible; (2) the resolved shear stress acting on the possible slip systems in the adjoining grain, this should be large and (3) the magnitude of the Burgers vector of the extrinsic dislocations left at the grain boundary following emission of dislocations, this should be a minimum. The Burgers vector of the generated dislocation is dictated primarily by condition (3).

  10. Fundamental study of spin-coating using in-situ analysis and simulation

    NASA Astrophysics Data System (ADS)

    Harumoto, Masahiko; Yoshida, Jun-ichi; Stokes, Harold; Tanaka, Yuji; Miyagi, Tadashi; Kaneyama, Koji; Pieczulewski, Charles; Asai, Masaya

    2015-03-01

    Spin coating has been used as a photoresist application method for many years, and consequently certain defects have been recognized through each resist generation; i-line, KrF, ArF, ArF immersion and, most recently, EUV. Last year we reported an in-situ analysis via high-speed video camera that proved to be useful for understanding defect formation such as non-uniformity spots within organic film coatings and post-develop water-mark defects. In this study, fingerprints known as `tiger stripes' around the wafer's edge were analyzed. This phenomenon, for example, is directly related to the wafer spin-speed and air-flow during the coat-processing. Utilizing a high-speed camera and 3D simulation, we reveal the mechanism of fingerprint generation for tiger stripe phenomena, confirm the mechanism with several different spin-speeds, and correlate these to defect inspection results. Furthermore, we will discuss the expansion to 450mmm wafers.

  11. Spreading of individual toner particles studied using in situ optical microscopy.

    PubMed

    Pettersson, Torbjörn; Fogden, Andrew

    2005-07-01

    This study develops and tests an experimental method to monitor in situ the dynamic spreading of individual toner particles on model substrates during heating, to simulate on laboratory scale the fusing sub-processes occurring in electrophotographic printing of paper. Real toner particles of cyan, magenta, yellow and black are transformed to perfect spheres by a temperature pre-treatment, then applied to the substrate, either high-energy clean glass or low-energy hydrophobised glass, and heated at rates up to 50 degrees C/min. The subsequent spreading as a function of time (and temperature) is recorded by an optical microscope and CCD camera mounted above the substrate, with the measured drop covering area used to calculate the corresponding toner-substrate-air contact angle. On the hydrophobic substrate the spreading is limited and equal for all four colours, while the substantially greater spreading on the hydrophilic substrate is accompanied by significant differences between the toner colours. In particular, the cyan and black toners are found to spread to almost twice the extent of the yellow particles. The dynamic spreading behaviour is interpreted in terms of complementary measurements of substrate and toner surface energy components and bulk toner rheology, and a simple empirical relation is proposed that fits very well the measurements for all toner and substrate types tested. In particular, the spreading relation is found to be determined only by the toner surface energy and its equilibrium contact angle, with no explicit dependence on toner viscosity.

  12. Dispersion stabilization of silver nanoparticles in synthetic lung fluid studied under in situ conditions.

    PubMed

    MacCuspie, Robert I; Allen, Andrew J; Hackley, Vincent A

    2011-06-01

    The dispersion stabilization of silver nanoparticles (AgNPs) in synthetic lung fluid was studied to interrogate the effects on colloidal stability due to the principal constituents of the fluid. The colloidal stability of 20 nm citrate-AgNPs dispersed in the presence of each constituent of the synthetic lung fluid (individually, the complete fluid, and without additives) was observed during titration of increasing sodium chloride concentration. A variety of complementary in situ measurement techniques were utilized, including dynamic light scattering, ultraviolet-visible absorption spectroscopy, atomic force microscopy, and small-angle X-ray scattering, which provided a collective set of information that enabled far better understanding of the dispersion behavior in the fluid than any one technique alone. It was observed that AgNPs continued to adsorb bovine serum albumin (BSA) protein from the synthetic lung fluid solution as the sodium chloride concentration increased, until a maximum BSA coating was achieved prior to reaching the physiological sodium chloride concentration of 154 mmol L(-1). BSA was determined to be the constituent of the synthetic lung fluid that is required to provide colloidal stability at high salt loadings, though the phospholipid constituent exerts a subtle effect. Additionally, as AgNPs are a distinctly different class of nanoparticles apart from the carbon nanotubes and titanium dioxide nanoparticles initially reported to be dispersible using this fluid, this work also demonstrates the broad applicability of synthetic lung fluid in providing stable dispersions for engineered nanoparticles for use in biological assays.

  13. Structure and Dynamics of Domains in Ferroelectric Nanostructures. In-situ TEM Studies

    SciTech Connect

    Pan, Xiaoqing

    2015-06-30

    The goal of this project was to explore the structure and dynamic behaviors of ferroelectric domains in ferroelectric thin films and nanostructures by advanced transmission electron microscopy (TEM) techniques in close collaboration with phase field modeling. The experimental techniques used include aberration-corrected sub-Å resolution TEM and in-situ TEM using a novel scanning tunneling microscopy (STM) - TEM holder that allows the direct observation of nucleation and dynamic evolution of ferroelectric domains under applied electric field. Specifically, this project was aimed to (1) to study the roles of static electrical boundary conditions and electrical charge in controlling the equilibrium domain structures of BiFeO3 thin films with controlled substrate constraints, (2) to explore the fundamental mechanisms of ferroelectric domain nucleation, growth, and switching under an applied electric field in both uniform thin films and nanostructures, and to understand the roles of crystal defects such as dislocations and interfaces in these processes, (3) to understand the physics of ferroelectric domain walls and the influence of defects on the electrical switching of ferroelectric domains.

  14. Dispersion stabilization of silver nanoparticles in synthetic lung fluid studied under in situ conditions

    SciTech Connect

    MacCuspie, R.I.; Allen, A.J.; Hackley, V.A.

    2014-09-24

    The dispersion stabilization of silver nanoparticles (AgNPs) in synthetic lung fluid was studied to interrogate the effects on colloidal stability due to the principal constituents of the fluid. The colloidal stability of 20 nm citrate-AgNPs dispersed in the presence of each constituent of the synthetic lung fluid (individually, the complete fluid, and without additives) was observed during titration of increasing sodium chloride concentration. A variety of complementary in situ measurement techniques were utilized, including dynamic light scattering, ultraviolet-visible absorption spectroscopy, atomic force microscopy, and small-angle X-ray scattering, which provided a collective set of information that enabled far better understanding of the dispersion behavior in the fluid than any one technique alone. It was observed that AgNPs continued to adsorb bovine serum albumin (BSA) protein from the synthetic lung fluid solution as the sodium chloride concentration increased, until a maximum BSA coating was achieved prior to reaching the physiological sodium chloride concentration of 154 mmol L{sup -1}. BSA was determined to be the constituent of the synthetic lung fluid that is required to provide colloidal stability at high salt loadings, though the phospholipid constituent exerts a subtle effect. Additionally, as AgNPs are a distinctly different class of nanoparticles apart from the carbon nanotubes and titanium dioxide nanoparticles initially reported to be dispersible using this fluid, this work also demonstrates the broad applicability of synthetic lung fluid in providing stable dispersions for engineered nanoparticles for use in biological assays.

  15. Boron phosphide under pressure: In situ study by Raman scattering and X-ray diffraction

    SciTech Connect

    Solozhenko, Vladimir L.; Kurakevych, Oleksandr O.; Le Godec, Yann; Kurnosov, Aleksandr V.; Oganov, Artem R.

    2014-07-21

    Cubic boron phosphide, BP, has been studied in situ by X-ray diffraction and Raman scattering up to 55 GPa at 300 K in a diamond anvil cell. The bulk modulus of B{sub 0} = 174(2) GPa has been established, which is in excellent agreement with our ab initio calculations. The data on Raman shift as a function of pressure, combined with equation-of-state (EOS) data, allowed us to estimate the Grüneisen parameters of the TO and LO modes of zinc-blende structure, γ{sub G}{sup TO }= 1.26 and γ{sub G}{sup LO }= 1.13, just like in the case of other A{sup III}B{sup V} diamond-like phases, for which γ{sub G}{sup TO }> γ{sub G}{sup LO }≅ 1. We also established that the pressure dependence of the effective electro-optical constant α is responsible for a strong change in relative intensities of the TO and LO modes from I{sub TO}/I{sub LO} ∼ 0.25 at 0.1 MPa to I{sub TO}/I{sub LO} ∼ 2.5 at 45 GPa, for which we also find excellent agreement between experiment and theory.

  16. Understanding the effects of PEMFC contamination from balance of plant assembly aids materials: In situ studies

    DOE PAGES

    Opu, Md.; Bender, G.; Macomber, Clay S.; ...

    2015-06-29

    In this study, in situ performance data were measured to assess the degree of contamination from leachates of five families of balance of plant (BOP) materials (i.e., 2-part adhesive, grease, thread lock/seal, silicone adhesive/seal and urethane adhesive/seal) broadly classified as assembly aids that may be used as adhesives and lubricants in polymer electrolyte membrane fuel cell (PEMFC) systems. Leachate solutions, derived from soaking the materials in deionized (DI) water at elevated temperature, were infused into the fuel cell to determine the effect of the leachates on fuel cell performance. During the contamination phase of the experiments, leachate solution was introducedmore » through a nebulizer into the cathode feed stream of a 50 cm2 PEMFC operating at 0.2 A/cm2 at 80°C and 32%RH. Voltage loss and high frequency resistance (HFR) were measured as a function of time and electrochemical surface area (ECA) before and after contamination were compared. Two procedures of recovery, one self-induced recovery with DI water and one driven recovery through cyclic voltammetry (CV) were investigated. Finally, performance results measured before and after contamination and after CV recovery are compared and discussed.« less

  17. Understanding the effects of PEMFC contamination from balance of plant assembly aids materials: In situ studies

    SciTech Connect

    Opu, Md.; Bender, G.; Macomber, Clay S.; Van Zee, J. W.; Dinh, Huyen N.

    2015-06-29

    In this study, in situ performance data were measured to assess the degree of contamination from leachates of five families of balance of plant (BOP) materials (i.e., 2-part adhesive, grease, thread lock/seal, silicone adhesive/seal and urethane adhesive/seal) broadly classified as assembly aids that may be used as adhesives and lubricants in polymer electrolyte membrane fuel cell (PEMFC) systems. Leachate solutions, derived from soaking the materials in deionized (DI) water at elevated temperature, were infused into the fuel cell to determine the effect of the leachates on fuel cell performance. During the contamination phase of the experiments, leachate solution was introduced through a nebulizer into the cathode feed stream of a 50 cm2 PEMFC operating at 0.2 A/cm2 at 80°C and 32%RH. Voltage loss and high frequency resistance (HFR) were measured as a function of time and electrochemical surface area (ECA) before and after contamination were compared. Two procedures of recovery, one self-induced recovery with DI water and one driven recovery through cyclic voltammetry (CV) were investigated. Finally, performance results measured before and after contamination and after CV recovery are compared and discussed.

  18. Field test for treatment verification of an in-situ enhanced bioremediation study

    SciTech Connect

    Taur, C.K.; Chang, S.C.

    1995-09-01

    Due to a leakage from a 12-inch pressurized diesel steel pipe four years ago, an area of approximately 30,000 square meters was contaminated. A pilot study applying the technology of in-situ enhanced bioremediation was conducted. In the study, a field test kit and on-site monitoring equipment were applied for site characterization and treatment verification. Physically, the enhanced bioremediation study consisted of an air extraction and air supply system, and a nutrition supply network. Certain consistent sampling methodology was employed. Progress was verified by daily monitoring and monthly verification. The objective of this study was to evaluate the capabilities of indigenous microorganisms to biodegrade the petroleum hydrocarbons with provision of oxygen and nutrients. Nine extraction wells and eight air sparging wells were installed. The air sparging wells injected the air into geoformation and the extraction wells provided the underground air circulation. The soil samples were obtained monthly for treatment verification by a Minuteman drilling machine with 2.5-foot-long hollow-stem augers. The samples were analyzed on site for TPH-diesel concentration by a field test kit manufactured by HNU-Hanby, Houston, Texas. The analytical results from the field test kit were compared with the results from an environmental laboratory. The TVPH concentrations of the air extracted from the vadose zone by a vacuum blower and the extraction wells were routinely monitored by a Foxboro FID and Cosmos XP-311A combustible air detector. The daily monitoring of TVPH concentrations provided the reliable data for assessing the remedial progress.

  19. In situ study of defect migration kinetics and self-healing of twin boundaries in heavy ion irradiated nanotwinned metals.

    PubMed

    Li, J; Yu, K Y; Chen, Y; Song, M; Wang, H; Kirk, M A; Li, M; Zhang, X

    2015-05-13

    High energy particles introduce severe radiation damage in metallic materials, such as Ag. Here we report on the study on twin boundary (TB) affected zone in irradiated nanotwinned Ag wherein time accumulative defect density and defect diffusivity are substantially different from those in twin interior. In situ studies also reveal surprising resilience and self-healing of TBs in response to radiation. This study provides further support for the design of radiation-tolerant nanotwinned metallic materials.

  20. Relationships Between Watershed Emergy Flow and Coastal New England Salt Marsh Structure, Function, and Condition

    EPA Science Inventory

    This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI. The field-collected data wer...

  1. Structure function analysis of two-scale Scalar Ramps. Part I: Theory and Modeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Structure functions are used to study the dissipation and inertial range scales of turbulent energy, to parameterize remote turbulence measurements, and to characterize ramp features in the turbulent field. The ramp features are associated with turbulent coherent structures, which dominate energy an...

  2. Note: Sample chamber for in situ x-ray absorption spectroscopy studies of battery materials

    SciTech Connect

    Pelliccione, CJ; Timofeeva, EV; Katsoudas, JP; Segre, CU

    2014-12-01

    In situ x-ray absorption spectroscopy (XAS) provides element-specific characterization of both crystalline and amorphous phases and enables direct correlations between electrochemical performance and structural characteristics of cathode and anode materials. In situ XAS measurements are very demanding to the design of the experimental setup. We have developed a sample chamber that provides electrical connectivity and inert atmosphere for operating electrochemical cells and also accounts for x-ray interactions with the chamber and cell materials. The design of the sample chamber for in situ measurements is presented along with example XAS spectra from anode materials in operating pouch cells at the Zn and Sn K-edges measured in fluorescence and transmission modes, respectively. (C) 2014 AIP Publishing LLC.

  3. In situ studies of a platform for metastable inorganic crystal growth and materials discovery

    PubMed Central

    Shoemaker, Daniel P.; Hu, Yung-Jin; Chung, Duck Young; Halder, Gregory J.; Chupas, Peter J.; Soderholm, L.; Mitchell, J. F.; Kanatzidis, Mercouri G.

    2014-01-01

    Rapid shifts in the energy, technological, and environmental demands of materials science call for focused and efficient expansion of the library of functional inorganic compounds. To achieve the requisite efficiency, we need a materials discovery and optimization paradigm that can rapidly reveal all possible compounds for a given reaction and composition space. Here we provide such a paradigm via in situ X-ray diffraction measurements spanning solid, liquid flux, and recrystallization processes. We identify four new ternary sulfides from reactive salt fluxes in a matter of hours, simultaneously revealing routes for ex situ synthesis and crystal growth. Changing the flux chemistry, here accomplished by increasing sulfur content, permits comparison of the allowable crystalline building blocks in each reaction space. The speed and structural information inherent to this method of in situ synthesis provide an experimental complement to computational efforts to predict new compounds and uncover routes to targeted materials by design. PMID:25024201

  4. In situ infrared study of adsorbed species during catalytic oxidation and carbon dioxide adsorption

    NASA Astrophysics Data System (ADS)

    Khatri, Rajesh A.

    2005-11-01

    Hydrogen is considered to be the fuel of the next century. Hydrogen can be produced by either water splitting using the solar or nuclear energy or by catalytic cracking and reforming of the fossil fuels. The water splitting process using solar energy and photovoltaics is a clean way to produce hydrogen, but it suffers from very low efficiency. A promising scheme to produce H 2 from natural gas involves following steps: (i) partial oxidation and reforming of natural gas to syngas, (ii) water-gas shift reaction to convert CO in the syngas to additional H2, (iii) separation of the H2 from CO2, and (iv) CO2 sequestration. The requirements for the above scheme are (i) a highly active coke resistant catalyst for generation of syngas by direct partial oxidation, (ii) a highly active sulfur tolerant catalyst for the water-gas shift reaction, and (iii) a low cost sorbent with high CO2 adsorption capacity for CO2 sequestration. This dissertation will address the mechanisms of partial oxidation, CO2 adsorption, and water-gas shift catalysis using in situ IR spectroscopy coupled with mass spectrometry (MS). The results from these studies will lead to a better understanding of the reaction mechanism and design of both the catalyst and sorbent for production of hydrogen with zero emissions. Partial oxidation of methane is studied over Rh/Al2O 3 catalyst to elucidate the reaction mechanism for synthesis gas formation. The product lead-lag relationship observed with in situ IR and MS results revealed that syngas is produced via a two-step reforming mechanism: the first step involving total oxidation of CH4 to CO2 and H 2O and the second step involving the reforming of unconverted methane with CO2 and H2O to form syngas. Furthermore, the Rh on the catalyst surface remains predominantly in the partially oxidized state (Rhdelta+ and Rh0). For the water-gas shift reaction, addition of Re to the Ni/CeO2 catalyst enhanced the water gas shift activity by a factor of three. The activity

  5. Effect of dentifrices on their remineralizing potential in artificial carious lesions: An in situ study

    PubMed Central

    Damle, Satyawan Gangaramji; Bector, Aditi; Damle, Dhanashree; Kaur, Simranjeet

    2016-01-01

    Background: The eventual sequel of dental caries is determined by the dynamic equilibrium between pathological factors which lead to demineralization and protective elements, which in turn leads to remineralization. Remineralization is the natural process for noncavitated demineralized lesions and relies on calcium and phosphate ions assisted by fluoride to rebuild a new surface on existing crystal remnants in subsurface lesions remaining after demineralization. Hence, the present study was designed to evaluate the efficacy of fluoride dentifrices in remineralizing artificial caries-like lesions in situ. Materials and Methods: A double-blind, randomized study with an initial washout period of 7 days was carried out for 3 weeks. Twenty volunteers were enrolled, who wore the intraoral cariogenicity test appliance having enamel slabs incorporated into them, for 3 weeks. 10 participants were instructed to use Group A dentifrice (fluoride) and the other 10 Group B dentifrice (nonfluoride) for brushing their teeth. The enamel slabs were analyzed by surface microhardness testing and scanning electron microscopy (SEM) at 3 intervals. Results: No significant differences was seen in the microhardness values recorded for Group A and Group B at baseline and after demineralization (P > 0.05); however Group B exhibited lesser microhardness compared to Group A, after intra-oral exposure (P < 0.05). In the SEM analysis, the Group A enamel surfaces had more regular and longer crystallites to those of the Group B. Conclusion: Fluoride dentifrices avert the decrease in enamel hardness and loss of minerals from the enamel surface to a large extent as compared to the nonfluoride dentifrices. PMID:26962320

  6. Study of the thermal stability of studtite by in situ Raman spectroscopy and DFT calculations

    NASA Astrophysics Data System (ADS)

    Colmenero, Francisco; Bonales, Laura J.; Cobos, Joaquín; Timón, Vicente

    2017-03-01

    The design of a safe spent nuclear fuel repository requires the knowledge of the stability of the secondary phases which precipitate when water reaches the fuel surface. Studtite is recognized as one of the secondary phases that play a key-role in the mobilization of the radionuclides contained in the spent fuel. Thereby, it has been identified as a product formed under oxidation conditions at the surface of the fuel, and recently found as a corrosion product in the Fukushima-Daiichi nuclear plant accident. Thermal stability is one of the properties that should be determined due to the high temperature of the fuel. In this work we report a detailed analysis of the structure and thermal stability of studtite. The structure has been studied both by experimental techniques (SEM, TGA, XRD and Raman spectroscopy) and theoretical DFT electronic structure and spectroscopic calculations. The comparison of the results allows us to perform for the first time the Raman bands assignment of the whole spectrum. The thermal stability of studtite has been analyzed by in situ Raman spectroscopy, with the aim of studying the effect of the heating rate and the presence of water. For this purpose, a new cell has been designed. The results show that studtite is stable under dry conditions only at temperatures below 30 °C, in contrast with the higher temperatures published up to date ( 130 °C). Opposite behaviour has been found when studtite is in contact with water; under these conditions studtite is stable up to 90 °C, what is consistent with the encounter of this phase after the Fukushima-Daiichi accident.

  7. Study of the thermal stability of studtite by in situ Raman spectroscopy and DFT calculations.

    PubMed

    Colmenero, Francisco; Bonales, Laura J; Cobos, Joaquín; Timón, Vicente

    2017-03-05

    The design of a safe spent nuclear fuel repository requires the knowledge of the stability of the secondary phases which precipitate when water reaches the fuel surface. Studtite is recognized as one of the secondary phases that play a key-role in the mobilization of the radionuclides contained in the spent fuel. Thereby, it has been identified as a product formed under oxidation conditions at the surface of the fuel, and recently found as a corrosion product in the Fukushima-Daiichi nuclear plant accident. Thermal stability is one of the properties that should be determined due to the high temperature of the fuel. In this work we report a detailed analysis of the structure and thermal stability of studtite. The structure has been studied both by experimental techniques (SEM, TGA, XRD and Raman spectroscopy) and theoretical DFT electronic structure and spectroscopic calculations. The comparison of the results allows us to perform for the first time the Raman bands assignment of the whole spectrum. The thermal stability of studtite has been analyzed by in situ Raman spectroscopy, with the aim of studying the effect of the heating rate and the presence of water. For this purpose, a new cell has been designed. The results show that studtite is stable under dry conditions only at temperatures below 30°C, in contrast with the higher temperatures published up to date (~130°C). Opposite behaviour has been found when studtite is in contact with water; under these conditions studtite is stable up to 90°C, what is consistent with the encounter of this phase after the Fukushima-Daiichi accident.

  8. A numerical study of a method for measuring the effective in situ sound absorption coefficient.

    PubMed

    Kuipers, Erwin R; Wijnant, Ysbrand H; de Boer, André

    2012-09-01

    The accuracy of a method [Wijnant et al., Proc. of ISMA 31, Leuven, Belgium (2010), Vol. 31] for measurement of the effective area-averaged in situ sound absorption coefficient is investigated. Based on a local plane wave assumption, this method can be applied to sound fields for which a model is not available. Investigations were carried out by means of finite element simulations for a typical case. The results show that the method is a promising method for determining the effective area-averaged in situ sound absorption coefficient in complex sound fields.

  9. An In Situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode

    DTIC Science & Technology

    1988-07-15

    Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode by DJ. Blackwood and S. Pons Prepared for publication in J...Secunt ClaMwfkation) An in situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode D.lc...SUBJECT TERMS (Continue on roverse if necessary and identify by block ’e’ 9ELD I GROUP I SUB-GROUP infrared spectroelectrochemistry ,adsorption, mercury I

  10. Regarding Chilcott's "Structural Functionalism as a Heuristic Device" Heuristically.

    ERIC Educational Resources Information Center

    Blot, Richard K.

    1998-01-01

    The heuristic value of Chilcott's essay lies less in its support for structural functionalism and more in its concern to reexamine theory in the work of earlier educational anthropologists for what earlier theories and practices can add to current research. (SLD)

  11. Twist decomposition of Drell-Yan structure functions: phenomenological implications

    NASA Astrophysics Data System (ADS)

    Brzemiński, Dawid; Motyka, Leszek; Sadzikowski, Mariusz; Stebel, Tomasz

    2017-01-01

    The forward Drell-Yan process in pp scattering at the LHC at √{S} = 14 TeV is considered. We analyze the Drell-Yan structure functions assuming the dominance of a Compton-like emission of a virtual photon from a fast quark scattering off the small x gluons. The color dipole framework is applied to perform quantitatively the twist decomposition of all the Drell-Yan structure functions. Two models of the color dipole scattering are applied: the Golec-Biernat-Wüsthoff model and the dipole cross section obtained from the Balitsky-Fadin-Kuraev-Lipatov evolution equation. The two models have essentially different higher twist content and the gluon transverse momentum distribution and lead to different significant effects beyond the collinear leading twist description. It is found that the gluon transverse momentum effects are significant in the Drell-Yan structure functions for all Drell-Yan pair masses M, and the higher twist effects become important for M ≲ 10GeV. It is found that the structure function W TT related to the A 2 angular coefficient and the Lam-Tung observable A 0 - A 2 are particularly sensitive to the gluon k T effects and to the higher twist effects. A procedure is suggested how to disentangle the higher twist effects from the gluon transverse momentum effects.

  12. Cognitive Adequacy in Structural-Functional Theories of Language

    ERIC Educational Resources Information Center

    Butler, Christopher S.

    2008-01-01

    This paper discusses the role played by cognition in three linguistic theories which may be labelled as "structural-functional": Functional (Discourse) Grammar, Role and Reference Grammar and Systemic Functional Grammar. It argues that if we are to achieve true cognitive adequacy, we must go well beyond the grammar itself to include the processes…

  13. Comparative spectroscopic studies on drug binding characteristics and protein surface hydrophobicity of native and modified forms of bovine serum albumin: Possible relevance to change in protein structure/function upon non-enzymatic glycation

    NASA Astrophysics Data System (ADS)

    Khodarahmi, Reza; Karimi, Seyyed Arash; Ashrafi Kooshk, Mohammad Reza; Ghadami, Seyyed Abolghasem; Ghobadi, Sirous; Amani, Mojtaba

    2012-04-01

    The interaction between serum albumin (SA) and drugs has provided an interesting ground for understanding of drug effects, especially in drug distribution and drug-drug interaction on SA, in the case of multi-drug therapy. Determination of the impact of various factors on drug-protein interaction is especially important upon significant binding of drug to albumin. In the present study, the interaction of two drugs (furosemide and indomethacin) with native and modified albumins were investigated by using various spectroscopic methods. Fluorescence data indicated that 1:1 binding of drugs to bovine serum albumin (BSA) is associated with quenching of albumin intrinsic fluorescence. The Job's plot also confirmed that drug binds to BSA via mentioned stoichiometry. Analysis of the quenching and thermodynamic parameters indicated that intermolecular interactions between drug and albumin may change upon protein modification. The theoretical analyses also suggested some conformational changes of interacting side chains in subdomain IIA binding site (at the vicinity of W237), which were in good agreement with experimental data. Decrease of protein surface hydrophobicity (PSH) was also observed upon both albumin modification and drug binding.

  14. Comparative spectroscopic studies on drug binding characteristics and protein surface hydrophobicity of native and modified forms of bovine serum albumin: possible relevance to change in protein structure/function upon non-enzymatic glycation.

    PubMed

    Khodarahmi, Reza; Karimi, Seyyed Arash; Ashrafi Kooshk, Mohammad Reza; Ghadami, Seyyed Abolghasem; Ghobadi, Sirous; Amani, Mojtaba

    2012-04-01

    The interaction between serum albumin (SA) and drugs has provided an interesting ground for understanding of drug effects, especially in drug distribution and drug-drug interaction on SA, in the case of multi-drug therapy. Determination of the impact of various factors on drug-protein interaction is especially important upon significant binding of drug to albumin. In the present study, the interaction of two drugs (furosemide and indomethacin) with native and modified albumins were investigated by using various spectroscopic methods. Fluorescence data indicated that 1:1 binding of drugs to bovine serum albumin (BSA) is associated with quenching of albumin intrinsic fluorescence. The Job's plot also confirmed that drug binds to BSA via mentioned stoichiometry. Analysis of the quenching and thermodynamic parameters indicated that intermolecular interactions between drug and albumin may change upon protein modification. The theoretical analyses also suggested some conformational changes of interacting side chains in subdomain IIA binding site (at the vicinity of W237), which were in good agreement with experimental data. Decrease of protein surface hydrophobicity (PSH) was also observed upon both albumin modification and drug binding.

  15. Isomerization and Oxidation in the Complementarity-Determining Regions of a Monoclonal Antibody: A Study of the Modification-Structure-Function Correlations by Hydrogen-Deuterium Exchange Mass Spectrometry.

    PubMed

    Yan, Yuetian; Wei, Hui; Fu, Ya; Jusuf, Sutjano; Zeng, Ming; Ludwig, Richard; Krystek, Stanley R; Chen, Guodong; Tao, Li; Das, Tapan K

    2016-02-16

    Chemical modifications can potentially change monoclonal antibody's (mAb) local or global conformation and therefore impact their efficacy as therapeutic drugs. Modifications in the complementarity-determining regions (CDRs) are especially important because they can impair the binding affinity of an antibody for its target and therefore drug potency as a result. In order to understand the impact on mAb attributes induced by specific chemical modifications within the CDR, hydrogen-deuterium exchange mass spectrometry (HDX MS) was used to interrogate the conformational impact of Asp isomerization and Met oxidation in the CDRs of a model monoclonal antibody (mAb1). Our results indicate that despite their proximity to each other, Asp54 isomerization and Met56 oxidation in CDR2 in the heavy chain of mAb1 result in opposing conformational impacts on the local and nearby regions, leading directly to different alterations on antibody-antigen binding affinity. This study revealed direct evidence of local and global conformational changes caused by two of the most common degradation pathways in the CDRs of a mAb and identified correlations between chemical modification, structure, and function of the therapeutic monoclonal antibody.

  16. In situ ATR and DRIFTS studies of the nature of adsorbed CO₂ on tetraethylenepentamine films.

    PubMed

    Wilfong, Walter Christopher; Srikanth, Chakravartula S; Chuang, Steven S C

    2014-08-27

    CO2 adsorption/desorption onto/from tetraethylenepentamine (TEPA) films of 4, 10, and 20 μm thicknesses were studied by in situ attenuated total reflectance (ATR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques under transient conditions. Molar absorption coefficients for adsorbed CO2 were used to determine the CO2 capture capacities and amine efficiencies (CO2/N) of the films in the DRIFTS system. Adsorption of CO2 onto surface and bulk NH2 groups of the 4 μm film produced weakly adsorbed CO2, which can be desorbed at 50 °C by reducing the CO2 partial pressure. These weakly adsorbed CO2 exhibit low ammonium ion intensities and could be in the form of ammonium-carbamate ion pairs and zwitterions. Increasing the film thickness enhanced the surface amine-amine interactions, resulting in strongly adsorbed ion pairs and zwitterions associated with NH and NH2 groups of neighboring amines. These adsorbed species may form an interconnected surface network, which slowed CO2 gas diffusion into and diminished access of the bulk amine groups (or amine efficiency) of the 20 μm film by a minimum of 65%. Desorption of strongly adsorbed CO2 comprising the surface network could occur via dissociation of NH3(+)/NH2(+)···NH2/NH ionic hydrogen bonds beginning from 60 to 80 °C, followed by decomposition of NHCOO(-)/NCOO(-) at 100 °C. These results suggest that faster CO2 diffusion and adsorption/desorption kinetics could be achieved by thinner layers of liquid or immobilized amines.

  17. A new stand-alone QEXAFS data acquisition system for in situ studies.

    PubMed

    Stötzel, Jan; Lützenkirchen-Hecht, Dirk; Frahm, Ronald

    2011-03-01

    To meet the demands of the QEXAFS (quick-scanning extended X-ray absorption fine structure) technique for a fast, user-friendly and flexible data acquisition a new stand-alone system with new software exploiting a multi-functional USB board was designed. The chosen approach allows the scanning of several analogue and digital data sources with up to 500000 samples each second over hours storable in binary or ASCII format without any dead-time. At the same time it is possible to visualize the acquired data instantaneously which provides a maximum of interactivity during the running experiment and also optimal conditions to select the best suited beamline and detector settings prior to each measurement. Furthermore, the QEXAFS monochromator and typically three current amplifiers are entirely controlled by the new software so that all monochromator settings can be synchronized with the data acquisition enabling programmed scans with alternating parameter sets. This versatile concept also enables the user to react immediately to changes in the sample during in situ studies. An interface to a three-axis stepper motor control unit is additionally included to control a sample stage which can again be synchronized with the data acquisition. Thus, spatially resolved scans and the usage of scan tools for sample alignment are feasible with the new system. Typical examples to demonstrate the features of the new data acquisition system are presented, the designed graphical user interface is described in detail and, furthermore, the crucial design parameters of a typical QEXAFS set-up are discussed.

  18. Conductivity percolation in loosely compacted microcrystalline cellulose: An in situ study by dielectric spectroscopy during densification.

    PubMed

    Nilsson, Martin; Frenning, Göran; Gråsjö, Johan; Alderborn, Göran; Strømme, Maria

    2006-10-19

    The present study aims at contributing to a complete understanding of the water-induced ionic charge transport in cellulose. The behavior of this transport in loosely compacted microcrystalline cellulose (MCC) powder was investigated as a function of density utilizing a new type of measurement setup, allowing for dielectric spectroscopy measurement in situ during compaction. The ionic conductivity in MCC was found to increase with increasing density until a leveling-out was observed for densities above approximately 0.7 g/cm3. Further, it was shown that the ionic conductivity vs density followed a percolation type behavior signifying the percolation of conductive paths in a 3D conducting network. The density percolation threshold was found to be between approximately 0.2 and 0.4 g/cm3, depending strongly on the cellulose moisture content. The observed percolation behavior was attributed to the forming of interparticulate bonds in the MCC and the percolation threshold dependence on moisture was linked to the moisture dependence of particle rearrangement and plastic deformation in MCC during compaction. The obtained results add to the understanding of the density-dependent water-induced ionic transport in cellulose showing that, at given moisture content, the two major parameters determining the magnitude of the conductivity are the connectedness of the interparticluate bonds and the connectedness of pores with a diameter in the 5-20 nm size range. At densities between approximately 0.7 and 1.2 g/cm3 both the bond and the pore networks have percolated, facilitating charge transport through the MCC compact.

  19. Study of Sn removal processes for in-situ collector cleaning

    NASA Astrophysics Data System (ADS)

    Elg, Daniel T.; Panici, Gianluca A.; Srivastava, Shailendra N.; Ruzic, D. N.

    2016-03-01

    An in-situ hydrogen plasma cleaning technique to clean Sn off of EUV collector optics is studied in detail. The cleaning process uses hydrogen radicals (formed in the hydrogen plasma) to interact with Sn-coated surfaces, forming SnH4 and being pumped away. This technique has been used to clean a 300mm-diameter stainless steel dummy collector optic, and EUV reflectivity of multilayer mirror samples was restored after cleaning Sn from them, validating the potential of this technology. This method has the potential to significantly reduce downtime and increase source availability. However, net Sn removal is limited by decomposition of the SnH4 molecule upon impact with the collector and the resulting redeposition of Sn. This is true in all cleaning systems that make use of hydrogen radicals. Thus, to guide the design of effective cleaning systems, the transport of Sn in the chamber, and the fundamental processes affecting it, must be understood. Accordingly, an investigation into these processes Sn removal is being performed. These processes include the advection of gas through the chamber, the creation of hydrogen radicals, the etching of Sn by radicals, and the surface decomposition of SnH4. In this paper, experiments to determine the radical density are presented, along with a theoretical plasma chemistry model that explains the processes behind radical creation and validates the radical density measurements. Additionally, experiments are shown that provide an insight into the etching of Sn by hydrogen radicals, yielding calculations of etching probability as well as showing that Sn etching is very sensitive to oxygen contamination and surface morphology.

  20. Structure-function relationship of king cobra cathelicidin.

    PubMed

    Zhang, Yong; Zhao, Hui; Yu, Guo-Yu; Liu, Xiao-Dong; Shen, Ji-Hong; Lee, Wen-Hui; Zhang, Yun

    2010-08-01

    King cobra cathelicidin (OH-CATH) is composed of 34 amino acid residues having strong antibacterial and very weak hemolytic activities as reported by us recently. OH-CATH can be served as a valuable template to develop novel therapeutic drugs. In this study, OH-CATH and six of its analogs were synthesized to explore their structure-function relationships based on their bactericidal and hemolytic activities. Experimental results of OH-CATH(3-34) and OH-CATH(5-34) indicated that the N-terminal 4 amino acid residues of OH-CATH played an important role on its hemolytic activity but had weak effects on its bactericidal activity. Among OH-CATH and its analogs, OH-CATH(5-34) had the lowest hemolytic activity while maintained strong antimicrobial activity. To evaluate its potential usage, the biological activities of OH-CATH(5-34) were compared with those of pexiganan. The bactericidal activity of OH-CATH(5-34) against 5 different species (11 laboratory strains) was 2-4 times stronger than that of pexiganan (4-16 microg/ml vs 8-32 microg/ml). Hemolytic activity of OH-CATH(5-34) against human erythrocytes was 0.69% while that of pexiganan was 16.5% at the dosage of 200 microg/ml. OH-CATH(5-34) showed very weak cytotoxic activities against primary rabbit ventricular endothelial cells and four human cancer cell lines whereas pexiganan showed strong cytotoxic activity against these five cell lines (IC(50)=20-90 microg/ml). The intravenous LD(50) value of OH-CATH(5-34) on mice was 7-fold higher than that of pexiganan (175 mg/kg vs 25mg/kg). Taken together, our results suggested that OH-CATH(5-34) should be considered as an excellent candidate for developing therapeutic drugs.

  1. A Next-Generation Hard X-Ray Nanoprobe Beamline for In Situ Studies of Energy Materials and Devices

    NASA Astrophysics Data System (ADS)

    Maser, Jörg; Lai, Barry; Buonassisi, Tonio; Cai, Zhonghou; Chen, Si; Finney, Lydia; Gleber, Sophie-Charlotte; Jacobsen, Chris; Preissner, Curt; Roehrig, Chris; Rose, Volker; Shu, Deming; Vine, David; Vogt, Stefan

    2014-01-01

    The Advanced Photon Source is developing a suite of new X-ray beamlines to study materials and devices across many length scales and under real conditions. One of the flagship beamlines of the APS upgrade is the In Situ Nanoprobe (ISN) beamline, which will provide in situ and operando characterization of advanced energy materials and devices under varying temperatures, gas ambients, and applied fields, at previously unavailable spatial resolution and throughput. Examples of materials systems include inorganic and organic photovoltaic systems, advanced battery systems, fuel cell components, nanoelectronic devices, advanced building materials and other scientifically and technologically relevant systems. To characterize these systems at very high spatial resolution and trace sensitivity, the ISN will use both nanofocusing mirrors and diffractive optics to achieve spots sizes as small as 20 nm. Nanofocusing mirrors in Kirkpatrick-Baez geometry will provide several orders of magnitude increase in photon flux at a spatial resolution of 50 nm. Diffractive optics such as zone plates and/or multilayer Laue lenses will provide a highest spatial resolution of 20 nm. Coherent diffraction methods will be used to study even small specimen features with sub-10 nm relevant length scale. A high-throughput data acquisition system will be employed to significantly increase operations efficiency and usability of the instrument. The ISN will provide full spectroscopy capabilities to study the chemical state of most materials in the periodic table, and enable X-ray fluorescence tomography. In situ electrical characterization will enable operando studies of energy and electronic devices such as photovoltaic systems and batteries. We describe the optical concept for the ISN beamline, the technical design, and the approach for enabling a broad variety of in situ studies. We furthermore discuss the application of hard X-ray microscopy to study defects in multi-crystalline solar cells, one

  2. A Next-Generation Hard X-Ray Nanoprobe Beamline for In Situ Studies of Energy Materials and Devices

    SciTech Connect

    Maser, Jong; Lai, Barry; Buonassisi, Toni; Cai, Zhonghou; Chen, Si; Finney, Lydia; Gleber, Sophie-Charlotte; Jacobsen, Chris; Preissner, Curt; Chris Roehrig; Rose, Volker; Shu, Deming; Vine, David; Vogt, Stefan

    2013-08-20

    The Advanced Photon Source is developing a suite of new X-ray beamlines to study materials and devices across many length scales and under real conditions. One of the flagship beamlines of the APS upgrade is the In Situ Nanoprobe (ISN) beamline, which will provide in situ and operando characterization of advanced energy materials and devices under varying temperatures, gas ambients, and applied fields, at previously unavailable spatial resolution and throughput. Examples of materials systems include inorganic and organic photovoltaic systems, advanced battery systems, fuel cell components, nanoelectronic devices, advanced building materials and other scientifically and technologically relevant systems. To characterize these systems at very high spatial resolution and trace sensitivity, the ISN will use both nanofocusing mirrors and diffractive optics to achieve spots sizes as small as 20 nm. Nanofocusing mirrors in Kirkpatrick–Baez geometry will provide several orders of magnitude increase in photon flux at a spatial resolution of 50 nm. Diffractive optics such as zone plates and/or multilayer Laue lenses will provide a highest spatial resolution of 20 nm. Coherent diffraction methods will be used to study even small specimen features with sub-10 nm relevant length scale. A high-throughput data acquisition system will be employed to significantly increase operations efficiency and usability of the instrument. The ISN will provide full spectroscopy capabilities to study the chemical state of most materials in the periodic table, and enable X-ray fluorescence tomography. In situ electrical characterization will enable operando studies of energy and electronic devices such as photovoltaic systems and batteries. We also describe the optical concept for the ISN beamline, the technical design, and the approach for enabling a broad variety of in situ studies. Furthermore, we discuss the application of hard X-ray microscopy to study defects in multi-crystalline solar

  3. FIELD STUDY: IN SITU OXIDATION OF 1,4-DIOXANE WITH OZONE AND HYDROGEN PEROXIDE

    EPA Science Inventory

    A pilot-scale field evaluation is underway to assess the effectiveness of in situ oxidation (using ozone with and without hydrogen peroxide) for remediation of 1,4-dioxane and chlorinated volatile organic compounds in groundwater at the Cooper Drum Company Superfund Site located ...

  4. In situ tests for water quality assessment: a case study in Pampean rivers.

    PubMed

    Graça, Manuel A S; Rodrígues-Capítulo, Alberto; Ocón, Carolina; Gómez, Nora

    2002-09-01

    Two invertebrate species (Hyalella curvispina and Palaemonetes argentinus) and one macrophyte (Egeria densa) from a naturally high nutrient content system (Pampean rivers of La Plata, Argentina) were evaluated for their potential use in situ assays aiming to assess changes in water quality. Invertebrates were individually placed in cylindrical chambers in polluted sections of rivers and in reference upstream sites. Mortality after 48 h was high in polluted and reduced in control sites. Mortality was also higher in situ assays than in laboratory static tests. Standard sections of the macrophyte were also deployed at the reference and control sites. Growth (7 days) in terms of mass increment (but not in length) was consistently reduced in polluted sites. Results of benthic invertebrate and periphitic algae surveys were consistent with the in situ tests: pollution resulted in a decrease in the number of taxa, taxa replacement and in changes in the value of the biotic indices Indice Biótico PAMPeano and Indice de Diatomeas Pampeano, indicating deterioration of water quality. In situ assays have a high potential as environmental tools in integrated approaches of bioassessment programs.

  5. In Situ Powder Diffraction Studies of Electrode Materials in Rechargeable Batteries.

    PubMed

    Sharma, Neeraj; Pang, Wei Kong; Guo, Zaiping; Peterson, Vanessa K

    2015-09-07

    The ability to directly track the charge carrier in a battery as it inserts/extracts from an electrode during charge/discharge provides unparalleled insight for researchers into the working mechanism of the device. This crystallographic-electrochemical information can be used to design new materials or modify electrochemical conditions to improve battery performance characteristics, such as lifetime. Critical to collecting operando data used to obtain such information in situ while a battery functions are X-ray and neutron diffractometers with sufficient spatial and temporal resolution to capture complex and subtle structural changes. The number of operando battery experiments has dramatically increased in recent years, particularly those involving neutron powder diffraction. Herein, the importance of structure-property relationships to understanding battery function, why in situ experimentation is critical to this, and the types of experiments and electrochemical cells required to obtain such information are described. For each battery type, selected research that showcases the power of in situ and operando diffraction experiments to understand battery function is highlighted and future opportunities for such experiments are discussed. The intention is to encourage researchers to use in situ and operando techniques and to provide a concise overview of this area of research.

  6. Influence of Laser Irradiation on Pits and Fissures: An In Situ Study

    PubMed Central

    Correa–Afonso, Alessandra M; Pécora, Jesus D

    2013-01-01

    Abstract Objective: The aim of this in situ study was to analyze the influence of the Er:YAG, Nd:YAG, and CO2 lasers on the enamel acid resistance of pits and fissures. Background data: The laser tissue interaction has been studied as a method of preventing occlusal caries. Methods: Thirteen volunteers wore palatal acrylic appliances containing human occlusal enamel blocks that were divided into four groups (G1, control; G2, Er:YAG; G3, Nd:YAG; G4, CO2). Each palatal acrylic appliance was used in the four studied groups and was used for 14 consecutive days. A sucrose solution was applied to the specimens six times per day. The specimens were then sectioned in half, and a microhardness test was applied. The other halves were analyzed using polarized light microscopy to measure the caries-like lesion areas, and a morphological analysis was conducted using a scanning electron microscope (SEM). Results: For the statistical analysis of the data obtained from the microhardness test (Knoop hardness number. [KHN]) (α=5%), Fisher's exact test was performed, and the group means were as follows: G1, 247±71; G2, 258±70; G3, 272±73; and G4, 298±56. The results demonstrated that the control group was significantly different from G3 and G4, which presented higher microhardness values. The Wilcoxon signed-rank test was used to analyze the data obtained from the caries-lesion area measurements (mm2) (α=5%) (G1, 0.01±1.08; G2, 0.13±0.18; G3, 0.05±0.17; and G4, 0.09±0.22). The results no showed significant differences among the groups in this analysis. Conclusions: Based on the results from the present study, it may be concluded that the CO2 and Nd:YAG lasers increased the enamel acid resistance in pits and fissures. PMID:23336742

  7. A study of microemulsions as prolonged-release injectables through in-situ phase transition.

    PubMed

    Wu, Zimei; Alany, Raid G; Tawfeek, Noor; Falconer, James; Zhang, Wenli; Hassan, Ibrahim M; Rutland, Michael; Svirskis, Darren

    2014-01-28

    Microemulsions (MEs) have been studied extensively as colloidal carriers for the delivery of both water-soluble and lipid-soluble drugs. Our previous study showed that addition of water to ME formulations resulted in phase transition to either liquid crystal (LC) or coarse emulsion (CE). The aim of this study was to investigate whether these MEs could be used as drug delivery vehicles for prolonged release through in-situ phase transition following extravascular injection. Three ME formulations from the same pseudo-ternary phase diagram were investigated with respect to their phase transition behavior, and in-vivo drug release; a coarse emulsion-forming ME (CE-ME), an oil rich LC-forming ME (LC-ME1), and an oil poor LC-forming ME (LC-ME2). CE-ME was a W/O ME and both LC-MEs were O/W type. The release profiles of (99m)Tc labeled MEs following subcutaneous (SC) injection in rabbits were investigated with gamma-scintigraphy. The CE-ME dispersed readily in water, forming a CE, whereas the LC-forming MEs formed 'depots' in water. Polarized microscopy revealed a LC boundary spontaneously formed at the water/ME interface for the LC-MEs with the LC-ME2 forming a substantially thicker LC layer. The CE resulting from the water-induced transition of the CE-forming ME had a higher viscosity than the MEs, but lower than the LCs resulted from LC-MEs. Compared to LC-ME1, LC-ME2 underwent more rapid phase transition and the resultant LC had significant higher viscosity. The LCs formed from both ME formulations exhibited pseudoplastic properties; increasing the shear rate decreased the apparent viscosity exponentially. Following SC injection into the animal thigh, the LC-MEs had more prolonged release of (99m)Tc in a first-order manner, than CE-ME. The oil poor LC-ME2 had the slowest release with a t1/2 of 77min, 2.3 times longer than the oil rich LC-ME1; consistent with the thickness of LC layer formation observed in-vitro and their relative viscosities. In conclusion, the present

  8. High-Energy Synchrotron X-Ray Diffraction for In Situ Diffuse Scattering Studies of Bulk Single Crystals

    NASA Astrophysics Data System (ADS)

    Daniels, John E.; Jo, Wook; Donner, Wolfgang

    2012-01-01

    High-energy synchrotron x-ray scattering offers a powerful technique for investigation of single-crystal material structures. Large, mm-sized crystals can be used, allowing complex in situ sample environments to be employed. Here, we demonstrate how this technique can be applied for the collection of single-crystal diffuse scattering volumes from the electro-active material 96%Bi0.5Na0.5TiO3-4%BaTiO3 while electric fields are applied in situ. The data obtained allow correlation of the atomic and nanoscale structures with the observed macroscopic electro-active properties of interest. This article presents a recent study relating the nanoscale stacking fault structure in BNT-BT to the relaxor-ferroelectric nature of the material [Daniels et al. in Appl. Phys. Lett. 98, 252904 (2011)], and extends this study with further experimental description and analysis.

  9. In situ scanning tunneling microscopy studies of the SEI formation on graphite electrodes for Li+-ion batteries

    NASA Astrophysics Data System (ADS)

    Seidl, Lukas; Martens, Slađana; Ma, Jiwei; Stimming, Ulrich; Schneider, Oliver

    2016-07-01

    The SEI-formation on graphitic electrodes operated as an Li+-ion battery anode in a standard 1 M LiPF6 EC/DMC (1 : 1) electrolyte has been studied in situ by EC-STM. Two different modes of in situ study were applied, one, which allowed to follow topographic and crystallographic changes (solvent cointercalation, graphite exfoliation, SEI precipitation on the HOPG basal plane) of the graphite electrode during SEI-formation, and the second, which gave an insight into the SEI precipitation on the HOPG basal plane in real time. From the in situ EC-STM studies, not only conclusions about the SEI-topography could be drawn, but also about the formation mechanism and the chemical composition, which strongly depend on the electrode potential. It was shown that above 1.0 V vs. Li/Li+ the SEI-formation is still reversible, since the molecular structure of the solvent molecules remains intact during an initial reduction step. During further reduction, the molecular structures of the solvents are destructed, which causes the irreversible charge loss. The STM studies were completed by electrochemical methods, like cyclic voltammetry, the potentiostatic intermittent titration technique and charge/discharge tests of MCMB electrodes.

  10. Variegation in Arum italicum leaves. A structural-functional study.

    PubMed

    La Rocca, Nicoletta; Rascio, Nicoletta; Pupillo, Paolo

    2011-12-01

    The presence of pale-green flecks on leaves (speckling) is a frequent character among herbaceous species from shady places and is usually due to local loosening of palisade tissue (air space type of variegation). In the winter-green Arum italicum L. (Araceae), dark-green areas of variegated leaf blades are ca. 400 μm thick with a chlorophyll content of 1080 mg m⁻² and a palisade parenchyma consisting of a double layer of oblong cells. Pale-green areas are 25% thinner, have 26% less chlorophyll and contain a single, loose layer of short palisade cells. Full-green leaves generally present only one compact layer of cylindrical palisade cells and the same pigment content as dark-green sectors, but the leaf blade is 13% thinner. A spongy parenchyma with extensive air space is present in all leaf types. Green cells of all tissues have normal chloroplasts. Assays of photosynthetic activities by chlorophyll fluorescence imaging and O₂ exchange measurements showed that variegated pale-green and dark-green sectors as well as full-green leaves have comparable photosynthetic activities on a leaf area basis at saturating illumination. However, full-green leaves require a higher saturating light with respect to variegated sectors, and pale-green sectors support relatively higher photosynthesis rates on a chlorophyll basis. We conclude that i) variegation in this species depends on number and organization of palisade cell layers and can be defined as a "variable palisade" type, and ii) the variegated habit has no limiting effects on the photosynthetic energy budget of A. italicum, consistent with the presence of variegated plants side by side to full-green ones in natural populations.

  11. A in Situ Study of Plasma Etching Surface Chemistry Using Reflection Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lucchesi, Robert Peter

    Plasma etching is an important process in semiconductor manufacturing. The present work describes a means by which plasma etching surface chemistry may be studied in situ. The systems of interest were the sulfur hexafluoride plasma etching of silicon and tungsten in a diode reactor. A reflection infrared spectrometer was designed and constructed to be able to scan the frequency region from about 550cm ^{-1} to 1300cm ^{-1}, and a plasma etch reactor was modified to allow access to the infrared beam. Reflection infrared spectroscopy (RIS) allows the measurement of light absorbed by molecules adsorbed on a reflective surface selectively from light absorbed by molecules in the gas phase. RIS applied to heavily doped silicon substrates had limited success. While sulfur fluorine species were detected on the surface during plasma etching, no silicon fluorine species were ever detected. The sulfur fluorine species (referred to as SF_{rm x}) were not seen under any circumstances in the absence of an SF_6 plasma. Severe baseline drift of the infrared spectrometer during plasma etching was the main reason for the limited success. However, the results were significant in that they demonstrated the presence of sulfur fluorine species during the plasma etching of silicon in an SF_6 plasma. The baseline drift problems experienced with silicon were not found when tungsten was studied. The same SF _{rm x} feature detected on silicon was also found on tungsten during etching in an SF_6 plasma, but was never seen in the absence of the plasma. A detailed experimental and theoretical study was performed to show that the surface absorption feature seen was actually due to SF _{rm x} adsorbed on the surface. A hysteresis behavior was observed in the SF_ {rm x} concentration as the plasma power was ramped up and subsequently decreased. Finally, it could not be concluded if SF_{rm x} participated in the etch reaction by fluorinating the tungsten surface, but the presence of SF_ {rm x} on

  12. In vitro and in vivo studies on ocular vitamin A palmitate cationic liposomal in situ gels.

    PubMed

    He, Wen; Guo, Xianxi; Feng, Min; Mao, Nina

    2013-12-31

    N-trimethyl chitosan (TMC) with different degree of quaternization (DQ) as the coating materials, vitamin A palmitate (VAP)-loaded cationic liposomes dispersed in thermo-sensitive in situ gels (ISG) with poloxamer 407 (P407) as the base were prepared in this study. VAP-loaded liposomes (VAPL) were prepared using a film dispersion method followed by TMC-coating with DQ of 20%, 40% and 60% (TMC20, TMC40 and TMC60), respectively, then dispersed in P407 solution to obtain TMC-coated VAPL ISG. The in vitro properties of the system including morphology, size, zeta potential, entrapment efficiency, drug release and ocular retention were investigated. The ocular retention in vivo, eye irritation and pharmacokinetics in aqueous humor of the system were also studied in rabbits. VAPL revealed a spherical surface with mean size below 100 nm and negative zeta potential. After TMC-coating, the morphology and entrapment efficiency showed no significant changes, while the mean size was increased, zeta potential was changed into positive, and drug release was further sustained, and above all was influenced by DQ of TMC. TMC-coated VAPL exhibited little effect on the gelation temperature of P407 solution, and at the P407 concentration of 25% (w/v), TMC-coated VAPL ISG had the gelation temperature closest to the eye surface (34 °C) after diluted by the artificial tears. Compared with uncoated VAPL ISG and the marketed Oculotect gels, TMC-coated VAPL ISG displayed more retarded drug release and gel corrosion with a good linear relationship between them, and the higher DQ was, the slower drug release and gel corrosion. The ocular retention time in vitro and in vivo of TMC-coated VAPL ISG were both notable prolonged with a positive correlation with DQ of TMC. Compared with the marketed gels, TMC60-coated VAPL ISG showed delayed Tmax, improved Cmax and AUC(0–24) in rabbit aqueous humor, suggesting the sustained drug release and better corneal penetration and absorption. The local

  13. In Situ Grazing Incidence X-Ray Diffraction Study of Electrochemically Deposited Pb Monolayer on Ag(111),

    DTIC Science & Technology

    1987-05-12

    potential for the deposition of Pb2 on a Pb electrode and hence is termed underpotential deposition (UPD). 19 No additional lead is deposited until...K. 0 In Situ Grazing Incidence X-ray Diffraction Study Interim Technical Report of Electrochemically Deposited Pb rMbno layers on...nunoalayer adsorbed at a metal-liquid interface. Diffraction peaks were * ~. observed from a monoalayer of lead electrochemicially deposited onto a

  14. Fetal t(5p;21q) misdiagnosed as monosomy 21: A plea for in situ hybridization studies

    SciTech Connect

    Gill, P.; Uhrich, S.; Cheng, E.; Disteche, C.

    1994-10-01

    We report a case of 45,XY,-5,-21,+der (5)t(5;21) (p13 or p14;q11.2 or q21) that was prenatally misdiagnosed as complete monosomy 21 and terminated at 24 weeks of gestation. Subsequent fluorescence in situ hybridization studies with a chromosome 21 painting probe documented the cryptic unbalanced translocation. 17 refs., 2 figs., 1 tab.

  15. In situ oxygen conditioning of /001/ MgO thin film substrates for film growth studies by electron microscopy

    NASA Technical Reports Server (NTRS)

    Moorhead, R. D.; Poppa, H.

    1979-01-01

    It was found that the in situ treatment of 001-plane single-crystal films of MgO (prepared by epitaxial growth from the vapor phase) at high temperatures with a jet of oxygen will produce a surface that is almost equivalent, for epitaxial studies, to surfaces with the same orientation prepared by vacuum cleavage of bulk single crystals. The effectiveness of the process is demonstrated by its impact on the epitaxy of silver.

  16. A study of myc-related gene expression in small cell lung cancer by in situ hybridization.

    PubMed Central

    Gu, J.; Linnoila, R. I.; Seibel, N. L.; Gazdar, A. F.; Minna, J. D.; Brooks, B. J.; Hollis, G. F.; Kirsch, I. R.

    1988-01-01

    The expression of myc-related genes (c-myc, N-myc, and L-myc) in small cell lung cancer (SCLC) was studied by RNA-RNA tissue in situ hybridization. The tissues investigated included cytospins of ten cell lines derived from patients with SCLC, four corresponding nude mouse xenografts from cell lines, and metastatic tumor tissue obtained by surgical biopsy and at autopsy. The probes were prepared as 35S labeled complementary RNA. The expression of each gene was demonstrated specifically by autoradiography in the cytoplasm of the neoplastic cell samples. The average levels of oncogene expression in each specimen corroborated previous data obtained by Northern blot assays. In addition, heterogeneity in gene expression from cell to cell in each sample was noted. This study represents the first attempt to demonstrate oncogene expression in lung cancer cell lines and tissues in situ, and confirms that the expression of these myc related genes can be seen in the primary tumor. The technique of RNA-RNA tissue in situ hybridization has great potential in answering fundamental questions of tumor cell heterogeneity and progression in SCLC. It should be useful in both prospective and retrospective studies. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:2456019

  17. Ordering pathway of block copolymers under dynamic thermal gradients studied by in situ GISAXS

    DOE PAGES

    Samant, Saumil; Strzalka, Joseph; Yager, Kevin G.; ...

    2016-10-31

    Dynamic thermal gradient-based processes for directed self-assembly of block copolymer (BCP) thin films such as cold zone annealing (CZA) have demonstrated much potential for rapidly fabricating highly ordered patterns of BCP domains with facile orientation control. As a demonstration, hexagonally packed predominantly vertical cylindrical morphology, technologically relevant for applications such as membranes and lithography, was achieved in 1 μm thick cylinder-forming PS-b-PMMA (cBCP) films by applying sharp thermal gradients (CZA-Sharp) at optimum sample sweep rates. A thorough understanding of the molecular level mechanisms and pathways of the BCP ordering that occur during this CZA-S process is presented, useful to fullymore » exploit the potential of CZA-S for large-scale BCP-based device fabrication. To that end, we developed a customized CZA-S assembly to probe the dynamic structure evolution and ordering of the PS-b-PMMA cBCP film in situ as it undergoes the CZA-S process using the grazing incidence small-angle X-ray scattering (GISAXS) technique. Four distinct regimes of BCP ordering were observed within the gradient that include microphase separation from an “as cast” unordered state (Regime I), evolution of vertical cylinders under a thermally imposed strain gradient (Regime II), reorientation of a fraction of cylinders due to preferential substrate interactions (Regime III), and finally grain-coarsening on the cooling edge (Regime IV). The ordering pathway in the different regimes is further described within the framework of an energy landscape. A novel aspect of this study is the identification of a grain-coarsening regime on the cooling edge of the gradient, previously obscure in zone annealing studies of BCPs. Furthermore, such insights into the development of highly ordered BCP nanostructures under template-free thermal gradient fields can potentially have important ramifications in the field of BCP-directed self-assembly and self

  18. Cheese rind communities provide tractable systems for in situ and in vitro studies of microbial diversity

    PubMed Central

    Wolfe, Benjamin E.; Button, Julie E.; Santarelli, Marcela; Dutton, Rachel J.

    2014-01-01

    SUMMARY Tractable microbial communities are needed to bridge the gap between observations of patterns of microbial diversity and mechanisms that can explain these patterns. We developed cheese rinds as model microbial communities by characterizing in situ patterns of diversity and by developing an in vitro system for community reconstruction. Sequencing of 137 different rind communities across 10 countries revealed 24 widely distributed and culturable genera of bacteria and fungi as dominant community members. Reproducible community types formed independent of geographic location of production. Intensive temporal sampling demonstrated that assembly of these communities is highly reproducible. Patterns of community composition and succession observed in situ can be recapitulated in a simple in vitro system. Widespread positive and negative interactions were identified between bacterial and fungal community members. Cheese rind microbial communities represent an experimentally tractable system for defining mechanisms that influence microbial community assembly and function. PMID:25036636

  19. Cheese rind communities provide tractable systems for in situ and in vitro studies of microbial diversity.

    PubMed

    Wolfe, Benjamin E; Button, Julie E; Santarelli, Marcela; Dutton, Rachel J

    2014-07-17

    Tractable microbial communities are needed to bridge the gap between observations of patterns of microbial diversity and mechanisms that can explain these patterns. We developed cheese rinds as model microbial communities by characterizing in situ patterns of diversity and by developing an in vitro system for community reconstruction. Sequencing of 137 different rind communities across 10 countries revealed 24 widely distributed and culturable genera of bacteria and fungi as dominant community members. Reproducible community types formed independent of geographic location of production. Intensive temporal sampling demonstrated that assembly of these communities is highly reproducible. Patterns of community composition and succession observed in situ can be recapitulated in a simple in vitro system. Widespread positive and negative interactions were identified between bacterial and fungal community members. Cheese rind microbial communities represent an experimentally tractable system for defining mechanisms that influence microbial community assembly and function.

  20. In Situ XANES Study of CuO/TiO2 Thin Films During Photodegradation of Methylene Blue

    SciTech Connect

    Hsiung Tungli; Wang, H. Paul; Wei Yuling

    2007-02-02

    Speciation of copper in the CuO/TiO2 thin film (synthesized by the doctor-blade deposition method) during photocatalytic decomposition of methylene blue has been studied by in situ X-ray absorption near-edge structural (XANES) spectroscopy. During the UV/VIS radiation (90 min), in the presence of methylene blue, a decrease of Cu(II) and an increases of Cu(0) and Cu(I) fractions in the CuO/TiO2 thin film are observed by in situ XANES. The r-space Fourier transformation EXAFS (extend X-ray absorption fine structural) spectra also show that the bond distance of Cu-O in the thin film is decreased by 0.03 A during photocatalytic degradation of methylene blue.

  1. Preliminary experiments on apparatus for in situ studies of microwave-driven reactions by small angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Whittaker, A. G.; Harrison, A.; Oakley, G. S.; Youngson, I. D.; Heenan, R. K.; King, S. M.

    2001-01-01

    In this article we describe apparatus for the study of the microwave-driven growth of particles in solution by in situ small angle neutron scattering (SANS). This apparatus has enabled the first preliminary experiments using microwave-activated in situ diffraction. We take iron oxide as the prototype system, but the technique may be extended to a wide variety of chemical reactions that deposit solids from solution. The key features of the apparatus are a microwave cavity with a modular construction that may be adapted to the geometric constraints of the diffractometer, and a computer-controlled microwave generator that may be set to maintain either constant pressure or temperature in the reaction vessel. In this particular piece of equipment the reaction vessel is adapted so that part of the sample fills a cell of identical construction to those commonly used in SANS measurements for optimal transmission of the neutron beam.

  2. MSATT Workshop on Innovative Instrumentation for the In Situ Study of Atmosphere-Surface Interactions on Mars

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr. (Editor); Waenke, Heinrich (Editor)

    1992-01-01

    Papers accepted for the Mars Surface and Atmosphere Through Time (MSATT) Workshop on Innovative Instruments for the In Situ Study of Atmosphere-Surface Interaction of Mars, 8-9 Oct. 1992 in Mainz, Germany are included. Topics covered include: a backscatter Moessbauer spectrometer (BaMS) for use on Mars; database of proposed payloads and instruments for SEI missions; determination of martian soil mineralogy and water content using the Thermal Analyzer for Planetary Soils (TAPS); in situ identification of the martian surface material and its interaction with the martian atmosphere using DTA/GC; mass spectrometer-pyrolysis experiment for atmospheric and soil sample analysis on the surface of Mars; and optical luminescence spectroscopy as a probe of the surface mineralogy of Mars.

  3. Electrosynthesis of poly(para)phenylene in an ionic liquid: cyclic voltammetry and in situ STM/tunnelling spectroscopy studies.

    PubMed

    Carstens, T; El Abedin, S Zein; Endres, F

    2008-02-22

    The electropolymerization of benzene in the air and water-stable ionic liquid 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate (HMIm)FAP is investigated. The study comprises cyclic voltammetry, IR and in situ STM/tunnelling spectroscopy measurements. The IR results indicate that poly(para)phenylene is the end product of the electropolymerization of benzene in the employed ionic liquid. The resulting conjugation lengths of the product fall between 19 and 21. A polymer reference electrode is used successfully for the electrochemical polymerization of benzene. The first in situ STM results show that the electropolymerization of benzene in the ionic liquid can be probed on the nanoscale and the band gap of the prepared polymer can be determined. The electrodeposited polymer film obtained at a constant potential of 1.0 V vs PPP (polyparaphenylene) exhibits a band gap of 2.9+/-0.2 eV.

  4. Color dipole cross section and inelastic structure function

    NASA Astrophysics Data System (ADS)

    Jeong, Yu Seon; Kim, C. S.; Luu, Minh Vu; Reno, Mary Hall

    2014-11-01

    Instead of starting from a theoretically motivated form of the color dipole cross section in the dipole picture of deep inelastic scattering, we start with a parametrization of the deep inelastic structure function for electromagnetic scattering with protons, and then extract the color dipole cross section. Using the parametrizations of F 2(ξ = x or W 2 , Q 2) by Donnachie-Landshoff and Block et al., we find the dipole cross section from an approximate form of the presumed dipole cross section convoluted with the perturbative photon wave function for virtual photon splitting into a color dipole with massless quarks. The color dipole cross section determined this way reproduces the original structure function within about 10% for 0 .1 GeV2 ≤ Q 2 ≤10 GeV2. We discuss the dipole cross section at large and small dipole sizes and compare our results with other parametrizations.

  5. Structure-function relationships of immunostimulatory polysaccharides: A review.

    PubMed

    Ferreira, Sónia S; Passos, Cláudia P; Madureira, Pedro; Vilanova, Manuel; Coimbra, Manuel A

    2015-11-05

    Immunostimulatory polysaccharides are compounds capable of interacting with the immune system and enhance specific mechanisms of the host response. Glucans, mannans, pectic polysaccharides, arabinogalactans, fucoidans, galactans, hyaluronans, fructans, and xylans are polysaccharides with reported immunostimulatory activity. The structural features that have been related with such activity are the monosaccharide and glycosidic-linkage composition, conformation, molecular weight, functional groups, and branching characteristics. However, the establishment of structure-function relationships is possible only if purified and characterized polysaccharides are used and selective structural modifications performed. Aiming at contributing to the definition of the structure-function relationships necessary to design immunostimulatory polysaccharides with potential for preventive or therapeutical purposes or to be recognized as health-improving ingredients in functional foods, this review introduces basic immunological concepts required to understand the mechanisms that rule the potential claimed immunostimulatory activity of polysaccharides and critically presents a literature survey on the structural features of the polysaccharides and reported immunostimulatory activity.

  6. Theoretical study of piezoelectrochemical reactions in molecular compression chambers: In-situ generation of molecular hydrogen

    NASA Astrophysics Data System (ADS)

    Pichierri, Fabio

    2016-09-01

    Nitrogen-containing molecular compression chambers (MCCs) undergo stepwise protonation followed by a 2-electron reduction step which affords molecular hydrogen in situ. This piezoelectrochemical reaction is favored by the high compression that characterizes the molecular skeleton of MCC and its fluorinated analogue. Besides H2, the MCCs are also capable of trapping molecular fluorine and the small monoatomic gases helium and neon. A topological analysis of the electronic charge density reveals the presence of closed-shell interactions between hosts and guests.

  7. Microstructural Studies of In-Situ Mesophase Transformation in the Fabrication of Carbon-Carbon Composites

    DTIC Science & Technology

    2005-03-01

    materials for lithium ion batteries . The principle behind the impregnation with in-situ transformation process is that a wetting molten monomer...catalyst mixture. Naphthalene was the precursor monomer, and aluminum chloride was chosen as the catalyst. Even though AlCl3 was retained in the...Distribution Stmt: Approved for public release; distribution unlimited 3.3.1. Naphthalene and Aluminum Chloride Catalyst The increase in

  8. In situ scanning tunneling microscopy study of Ca-modified rutile TiO2(110) in bulk water.

    PubMed

    Serrano, Giulia; Bonanni, Beatrice; Kosmala, Tomasz; Di Giovannantonio, Marco; Diebold, Ulrike; Wandelt, Klaus; Goletti, Claudio

    2015-01-01

    Despite the rising technological interest in the use of calcium-modified TiO2 surfaces in biomedical implants, the Ca/TiO2 interface has not been studied in an aqueous environment. This investigation is the first report on the use of in situ scanning tunneling microscopy (STM) to study calcium-modified rutile TiO2(110) surfaces immersed in high purity water. The TiO2 surface was prepared under ultrahigh vacuum (UHV) with repeated sputtering/annealing cycles. Low energy electron diffraction (LEED) analysis shows a pattern typical for the surface segregation of calcium, which is present as an impurity on the TiO2 bulk. In situ STM images of the surface in bulk water exhibit one-dimensional rows of segregated calcium regularly aligned with the [001] crystal direction. The in situ-characterized morphology and structure of this Ca-modified TiO2 surface are discussed and compared with UHV-STM results from the literature. Prolonged immersion (two days) in the liquid leads to degradation of the overlayer, resulting in a disordered surface. X-ray photoelectron spectroscopy, performed after immersion in water, confirms the presence of calcium.

  9. Application of Mythen detector: In-situ XRD study on the thermal expansion behavior of metal indium

    NASA Astrophysics Data System (ADS)

    Du, Rong; Chen, ZhongJun; Cai, Quan; Fu, JianLong; Gong, Yu; Wu, ZhongHua

    2016-07-01

    A Mythen detector has been equipped at the beamline 4B9A of Beijing Synchrotron Radiation Facility (BSRF), which is expected to enable BSRF to perform time-resolved measurement of X-ray diffraction (XRD) full-profiles. In this paper, the thermal expansion behavior of metal indium has been studied by using the in-situ XRD technique with the Mythen detector. The indium was heated from 303 to 433 K with a heating rate of 2 K/min. The in-situ XRD full-profiles were collected with a rate of one profile per 10 seconds. Rietveld refinement was used to extract the structural parameters. The results demonstrate that these collected quasi-real-time XRD profiles can be well used for structural analysis. The metal indium was found to have a nonlinear thermal expansion behavior from room temperature to the melting point (429.65 K). The a-axis of the tetragonal unit cell expands with a biquadratic dependency on temperature, while the c-axis contracts with a cubic dependency on temperature. By the time-resolved XRD measurements, it was observed that the [200] preferred orientation can maintain to about 403.15 K. While (110) is the last and detectable crystal plane just before melting of the polycrystalline indium foil. This study is not only beneficial to the application of metal indium, but also exhibits the capacity of in-situ time-resolved XRD measurements at the X-ray diffraction station of BSRF.

  10. Spin structure functions: Proton / deuteron measurements in the resonance region

    SciTech Connect

    Mark Jones; RSS Collaboration

    2006-02-01

    The RSS experiment ran in Hall C at Jefferson Lab and measured the proton and deuteron beam-target asymmetries for parallel and perpendicular target fields over a W range from pion threshold to 1.9 GeV at Q{sup 2} {approx} 1.3 GeV{sup 2}. Preliminary results for the proton spin structure functions g{sub 1} and g{sub 2} are presented.

  11. Precision measurement of the neutron spin dependent structure functions

    SciTech Connect

    Kolomensky, Y.G.

    1997-02-01

    In experiment E154 at the Stanford Linear Accelerator Center the spin dependent structure function g{sub 1}{sup n} (x, Q{sup 2}) of the neutron was measured by scattering longitudinally polarized 48.3 GeV electrons off a longitudinally polarized {sup 3}He target. The high beam energy allowed the author to extend the kinematic coverage compared to the previous SLAC experiments to 0.014 {le} x {le} 0.7 with an average Q{sup 2} of 5 GeV{sup 2}. The author reports the integral of the spin dependent structure function in the measured range to be {integral}{sub 0.014}{sup 0.7} dx g{sub 1}{sup n}(x, 5 GeV{sup 2}) = {minus}0.036 {+-} 0.004(stat.) {+-} 0.005(syst.). The author observes relatively large values of g{sub 1}{sup n} at low x that call into question the reliability of data extrapolation to x {r_arrow} 0. Such divergent behavior disagrees with predictions of the conventional Regge theory, but is qualitatively explained by perturbative QCD. The author performs a Next-to-Leading Order perturbative QCD analysis of the world data on the nucleon spin dependent structure functions g{sub 1}{sup p} and g{sub 1}{sup n} paying careful attention to the experimental and theoretical uncertainties. Using the parameterizations of the helicity-dependent parton distributions obtained in the analysis, the author evolves the data to Q{sup 2} = 5 GeV{sup 2}, determines the first moments of the polarized structure functions of the proton and neutron, and finds agreement with the Bjorken sum rule.

  12. Surfactant flooding technology for in situ cleanup of contaminated soils and aquifers---A feasibility study

    SciTech Connect

    Porzucek, C.

    1989-11-01

    The process of in situ, surfactant-enhanced soil washing has been investigated to determine its usefulness and limitations. Previous work on this subject has been reviewed critically. Entrapment/displacement mechanisms of nonaqueous phase liquids (NAPLs) in porous media have been identified and are discussed. The effect of surfactant on each of these mechanisms has been investigated. A joint research project has been initiated with Howard University personnel to determine the effect of surfactant on contaminants that have sorbed onto soil surfaces. Results of this research are necessary to more fully determine the limitations of in situ, surfactant-enhanced soil washing. However, based on field observations of NAPLs and modification of an existing mass-transfer-based model, it is apparent that in situ, surfactant-enhanced soil washing alone will not be a sufficient remedial action plan because it cannot displace enough contaminant to clean the soil to within the Environmental Protection Agency's (EPA's) guidelines of cleanliness. The process shows the most promise when it is used in conjunction with another remedial action plan such as biorestoration. 47 refs., 3 figs., 1 tab.

  13. Studies on different iron source absorption by in situ ligated intestinal loops of broilers.

    PubMed

    Jia, Y F; Jiang, M M; Sun, J; Shi, R B; Liu, D S

    2015-02-01

    The objective of this study was to investigate the iron source absorption in the small intestine of broiler. In situ ligated intestinal loops of 70 birds were poured into one of seven solutions, including inorganic iron (FeSO4, Fe2(SO4)3), organic Fe glycine chelate (Fe-Gly(II), Fe-Gly(III)), the mixtures (FeSO4 with glycine (Fe+Gly(II)), Fe2(SO4)3 with glycine (Fe+Gly(III)), and no Fe source (control). The total volume of 3-mL solution (containing 1 mg of elemental Fe) was injected into intestinal loops, and then 120-min incubation was performed. Compared with inorganic iron groups, in which higher FeSO4 absorption than Fe2(SO4)3 was observed, supplementation with organic Fe glycine chelate significantly increased the Fe concentration in the duodenum and jejunum (P < 0.05), however, decreased DMT1 and DcytB messenger RNA (mRNA) levels (P < 0.05). Organic Fe glycine chelate (Fe-Gly(II), Fe-Gly(III)) increased serum iron concentration (SI), compared with inorganic 3 valence iron groups (Fe2(SO4)3 and Fe+Gly(III)) (P < 0.05); moreover, lower TIBC value was observed for the chelate (P < 0.05); however, mixture of inorganic iron and glycine did not have a positive role at DMT1 and DcytB mRNA levels, SI and Fe concentrations in the small intestine. Those results indicated that the absorption of organic Fe glycine chelate was more effective than that of inorganic Fe, and the orders of iron absorption in the small intestine were: Fe-Gly(II), Fe-Gly(III) > FeSO4, Fe+Gly(II) > Fe2(SO4)3, Fe+Gly(III). Additionally, the simple mixture of inorganic iron and glycine could not increase Fe absorption, and the duodenum was the main site of Fe absorption in the intestines of broilers and the ileum absorbed iron rarely.

  14. In-situ Micro-structural Studies of Gas Hydrate Formation in Sedimentary Matrices

    NASA Astrophysics Data System (ADS)

    Kuhs, Werner F.; Chaouachi, Marwen; Falenty, Andrzej; Sell, Kathleen; Schwarz, Jens-Oliver; Wolf, Martin; Enzmann, Frieder; Kersten, Michael; Haberthür, David

    2015-04-01

    The formation process of gas hydrates in sedimentary matrices is of crucial importance for the physical and transport properties of the resulting aggregates. This process has never been observed in-situ with sub-micron resolution. Here, we report on synchrotron-based micro-tomographic studies by which the nucleation and growth processes of gas hydrate were observed in different sedimentary matrices (natural quartz, glass beds with different surface properties, with and without admixtures of kaolinite and montmorillonite) at varying water saturation. The nucleation sites can be easily identified and the growth pattern is clearly established. In under-saturated sediments the nucleation starts at the water-gas interface and proceeds from there to form predominantly isometric single crystals of 10-20μm size. Using a newly developed synchrotron-based method we have determined the crystallite size distributions (CSD) of the gas hydrate in the sedimentary matrix confirming in a quantitative and statistically relevant manner the impressions from the tomographic reconstructions. It is noteworthy that the CSDs from synthetic hydrates are distinctly smaller than those of natural gas hydrates [1], which suggest that coarsening processes take place in the sedimentary matrix after the initial hydrate formation. Understanding the processes of formation and coarsening may eventually permit the determination of the age of gas hydrates in sedimentary matrices [2], which are largely unknown at present. Furthermore, the full micro-structural picture and its evolution will enable quantitative digital rock physics modeling to reveal poroelastic properties and in this way to support the exploration and exploitation of gas hydrate resources in the future. [1] Klapp S.A., Hemes S., Klein H., Bohrmann G., McDonald I., Kuhs W.F. Grain size measurements of natural gas hydrates. Marine Geology 2010; 274(1-4):85-94. [2] Klapp S.A., Klein H, Kuhs W.F. First determination of gas hydrate

  15. Cortactin gene amplification and expression in breast cancer: a chromogenic in situ hybridisation and immunohistochemical study.

    PubMed

    Dedes, Konstantin J; Lopez-Garcia, Maria-Angeles; Geyer, Felipe C; Lambros, Maryou B K; Savage, Kay; Vatcheva, Radost; Wilkerson, Paul; Wetterskog, Daniel; Lacroix-Triki, Magali; Natrajan, Rachael; Reis-Filho, Jorge S

    2010-12-01

    Amplification of 11q13 is found in approximately 15% of breast cancers. Cyclin D1 (CCND1) has been reported to be the 'driver' of this amplicon, however, multiple genes map to the smallest region of amplification of 11q13. Out of these genes, cortactin (CTTN) has been shown to be consistently overexpressed at the mRNA level in tumours harbouring 11q13 amplification. The aims of this study are to define whether CTTN is consistently co-amplified with the main core of the 11q13 amplicon, whether it is consistently overexpressed when amplified and to determine correlations between CTTN amplification and overexpression with clinicopathological features of breast cancers and survival of breast cancer patients. CTTN and CCND1 chromogenic in situ hybridisation (CISH) probes and a validated monoclonal antibody against CTTN were applied to a tissue microarray of a cohort of breast cancers from patients treated with anthracycline-based chemotherapy. CTTN and CCND1 amplifications were found in 12.3 and 12.4% of cases, respectively. All cases harbouring CTTN amplification also displayed CCND1 amplification. High expression of CTTN was found in 10.8% of cases and was associated with CTTN amplification, expression of 'basal' markers and topoisomerase IIα. Exploratory subgroup analysis of tumours devoid of 11q13 amplification revealed that high expression of CTTN in the absence of CTTN gene amplification was associated with lymph node negative disease, lack of hormone receptors and FOXA1, expression of 'basal' markers, high Ki-67 indices, p53 nuclear expression, and basal-like and triple negative phenotypes. CTTN expression and CTTN gene amplification were not associated with disease-, metastasis-free and overall survival. In conclusion, CTTN is consistently co-amplified with CCND1 and expressed at higher levels in breast cancers harbouring 11q13 amplification, suggesting that CTTN may also constitute one of the drivers of this amplicon. CTTN expression is not associated with the

  16. Thermal decomposition of t-butylamine borane studied by in situ solid state NMR

    SciTech Connect

    Feigerle, J.; Smyrl, N. R.; Morrell, J. S.; Stowe, A. C.

    2010-03-18

    of the amine borane fuel more feasible [22]. In the present study, tert-butylamine borane is investigated by heteronuclear in situ solid state NMR to understand hydrogen release from a hydrocarbon containing amine borane. tbutylamine borane has similar physical properties to amine borane with a melting point of 96 C. A single proton has been replaced with a t-butylamine group resulting in a weakening of the dihydrogen bonding framework. t-butylamine borane has a theoretical gravimetric hydrogen density of 15.1%; however, isobutane can also be evolved rather than hydrogen. If decomposition yields one mole isobutane and two moles hydrogen, 4.5 wt% H2 gas will be evolved. More importantly for the present work, the resulting spent fuel should be comprised of both (BNH)n and (CBNH)n polyimidoboranes.

  17. In situ TEM study of stability of TaRhx diffusion barriers using a novel sample preparation method.

    PubMed

    Dalili, Neda; Li, Peng; Kupsta, Martin; Liu, Qi; Ivey, Douglas G

    2014-03-01

    The atomic diffusion mechanisms associated with metallurgical failure of TaRhx diffusion barriers for Cu metallizations were studied by in situ transmission electron microscopy (TEM). The issues related to in situ heating of focused ion beam (FIB) prepared cross-sectional TEM samples that contain Cu thin films are discussed. The Cu layer in Si/(13 nm)TaRhx/Cu stacks showed grain growth and formation of voids at temperatures exceeding 550°C. For Si/(43 nm)TaRhx/Cu stacks, grain growth of Cu was delayed to higher temperatures, i.e., 700°C, and void formation was not observed. Extensive surface diffusion of Cu, however, preceded bulk diffusion. Therefore, a 10 nm film of electron beam evaporated C was deposited on both sides of the TEM lamellae to limit surface diffusion. This processing technique allowed for direct observation of atomic diffusion and reaction mechanisms across the TaRhx interface. Failure occurred by nucleation of orthorhombic RhSi particles at the Si/TaRhx interface. Subsequently, the barrier at areas adjacent to RhSi particles was depleted in Rh. This created lower density areas in the barrier, which facilitated diffusion of Cu to the Si substrate to form Cu3Si. The morphology of an in situ annealed lamella was compared with an ex situ bulk annealed sample, which showed similar reaction morphology. The sample preparation method developed in this study successfully prevented surface diffusion/delamination of the Cu layer and can be employed to understand the metallurgical failure of other potential diffusion barriers.

  18. In-Situ Neutron Diffraction Studies of Complex Hydrogen Storage Materials

    SciTech Connect

    Yelon, William B.

    2013-05-13

    should make it a very valuable resource for the study of oxides being considered for application to solid oxide fuel cells (SOFCs), in that materials can be studied at potential operating temperatures in both reducing and oxidizing environments to determine their stoichiometry, and lattice parameters. Our research, which was predicated, in part, on the use of hydrogenous samples (as opposed to deuteration), demonstrated that such studies are feasible and can yield high quality, refinable data. The precision of the refined hydrogen positions appears to be more than adequate for theory calculations (molecular modeling-thermodynamics) and the uncertainty is certainly less than that achieved by attempting to extrapolate the hydrogen positions from refined deuterium positions. In fact the 2008 annual report from the Institute Laue Langevin (ILL), the world's premier neutron scattering laboratory, highlights: Another trend is the increasing interest in hydrogen. This defies the widespread assumption that neutron diffraction experiments need to be done at deuterated samples. In situ experiments on phase transitions involving hydrogen and in particular on the real time behaviour of hydrogen-storage systems increase in number and scope. Our work in this area predates the ILL efforts be several years. Unfortunately, the productivity of our program was significantly curtailed by the unavailability of the MURR powder diffractometer for almost all of the second years of the project. The diffractometer was disassembled to allow partial extraction of the beam tube and replacement of the graphite element that is penetrated by the beam tube. Re-commissioning of the instrument was substantially delayed by errors of the MURR engineering staff, which failed to properly reinstall the sapphire filter that conditions the beam prior to the neutron monochromator, and reduces the radiological background to acceptable levels.

  19. Structure-function clustering in multiplex brain networks

    NASA Astrophysics Data System (ADS)

    Crofts, J. J.; Forrester, M.; O'Dea, R. D.

    2016-10-01

    A key question in neuroscience is to understand how a rich functional repertoire of brain activity arises within relatively static networks of structurally connected neural populations: elucidating the subtle interactions between evoked “functional connectivity” and the underlying “structural connectivity” has the potential to address this. These structural-functional networks (and neural networks more generally) are more naturally described using a multilayer or multiplex network approach, in favour of standard single-layer network analyses that are more typically applied to such systems. In this letter, we address such issues by exploring important structure-function relations in the Macaque cortical network by modelling it as a duplex network that comprises an anatomical layer, describing the known (macro-scale) network topology of the Macaque monkey, and a functional layer derived from simulated neural activity. We investigate and characterize correlations between structural and functional layers, as system parameters controlling simulated neural activity are varied, by employing recently described multiplex network measures. Moreover, we propose a novel measure of multiplex structure-function clustering which allows us to investigate the emergence of functional connections that are distinct from the underlying cortical structure, and to highlight the dependence of multiplex structure on the neural dynamical regime.

  20. Sum Rules and Moments of the Nucleon Spin Structure Functions

    SciTech Connect

    Jian-Ping Chen; Alexandre Deur; Zein-Eddine Meziani

    2005-08-01

    The nucleon has been used as a laboratory to investigate its own spin structure and Quantum Chromodynamics. New experimental data on nucleon spin structure at low to intermediate momentum transfers combined with existing high momentum transfer data offer a comprehensive picture of the transition region from the confinement regime of the theory to its asymptotic freedom regime. Insight for some aspects of the theory is gained by exploring lower moments of spin structure functions and their corresponding sum rules (i.e. the Gerasimov-Drell-Hearn, Bjorken and Burkhardt-Cottingham). These moments are expressed in terms of an operator product expansion using quark and gluon degrees of freedom at moderately large momentum transfers. The sum rules are verified to a good accuracy assuming that no singular behavior of the structure functions is present at very high excitation energies. The higher twist contributions have been examined through the moments evolution as the momentum transfer varies from higher to lower values. Furthermore, QCD-inspired low energy effective theories, which explicitly include chiral symmetry breaking, are tested at low momentum transfers. The validity of these theories is further examined as the momentum transfer increases to moderate values. It is found that chiral perturbation calculations agree reasonably well with the first moment of the spin structure function g{sub 1} at momentum transfer of 0.1 GeV{sup 2} but fail to reproduce the neutron data in the case of the generalized polarizability {delta}{sub LT}.

  1. In Situ Studies on Twin-Thickness-Dependent Distribution of Defect Clusters in Heavy Ion-Irradiated Nanotwinned Ag

    NASA Astrophysics Data System (ADS)

    Li, Jin; Chen, Y.; Wang, H.; Zhang, X.

    2017-01-01

    Recent studies have shown that twin boundaries are effective defect sinks in heavy ion irradiated nanotwinned (nt) metals. Prior in situ radiation studies on nt Ag at room temperature indicate that the accumulative defect concentration is higher in center areas in the 60-nm-thick twins, and twin boundaries are distorted and self-heal during the absorption of different types of defect clusters. In this follow-up study, we show that the spatial distribution of accumulative defect concentrations in nt metals has a clear dependence on twin thickness, and in certain cases, the trend of spatial distribution is reversed. Potential mechanisms for the counterintuitive findings are discussed.

  2. In Situ Studies on Twin-Thickness-Dependent Distribution of Defect Clusters in Heavy Ion-Irradiated Nanotwinned Ag

    NASA Astrophysics Data System (ADS)

    Li, Jin; Chen, Y.; Wang, H.; Zhang, X.

    2017-03-01

    Recent studies have shown that twin boundaries are effective defect sinks in heavy ion irradiated nanotwinned (nt) metals. Prior in situ radiation studies on nt Ag at room temperature indicate that the accumulative defect concentration is higher in center areas in the 60-nm-thick twins, and twin boundaries are distorted and self-heal during the absorption of different types of defect clusters. In this follow-up study, we show that the spatial distribution of accumulative defect concentrations in nt metals has a clear dependence on twin thickness, and in certain cases, the trend of spatial distribution is reversed. Potential mechanisms for the counterintuitive findings are discussed.

  3. In situ quantitative and kinetic study by Fourier transform raman spectroscopy of reaction between nitriles and hydroperoxides

    NASA Astrophysics Data System (ADS)

    Vacque, V.; Dupuy, N.; Sombret, B.; Huvenne, J. P.; Legrand, P.

    1997-06-01

    The reaction of nitrile with alkaline hydrogen peroxide has been studied kinetically by means of iodometry several times. We proposed to set up an in situ analytical method to follow the consumption of nitrile. We applied FT-Raman spectroscopy coupled with a partial least-squares quantitative method to the study the reactions of hydrogen peroxide or tert-butyl hydroperoxide on benzonitrile and acetonitrile. The results obtained led us to conclusions on the reactivity of the hydroperoxides and on the rate of consumption of nitrile. Our study made also clear that FT-Raman spectroscopy was a convenient tool for controlling industrial processes.

  4. Design study of an in situ PET scanner for use in proton beam therapy

    NASA Astrophysics Data System (ADS)

    Surti, S.; Zou, W.; Daube-Witherspoon, M. E.; McDonough, J.; Karp, J. S.

    2011-05-01

    Proton beam therapy can deliver a high radiation dose to a tumor without significant damage to surrounding healthy tissue or organs. One way of verifying the delivered dose distribution is to image the short-lived positron emitters produced by the proton beam as it travels through the patient. A potential solution to the limitations of PET imaging in proton beam therapy is the development of a high sensitivity, in situ PET scanner that starts PET imaging almost immediately after patient irradiation while the patient is still lying on the treatment bed. A partial ring PET design is needed for this application in order to avoid interference between the PET detectors and the proton beam, as well as restrictions on patient positioning on the couch. A partial ring also allows us to optimize the detector separation (and hence the sensitivity) for different patient sizes. Our goal in this investigation is to evaluate an in situ PET scanner design for use in proton therapy that provides tomographic imaging in a partial ring scanner design using time-of-flight (TOF) information and an iterative reconstruction algorithm. GEANT4 simulation of an incident proton beam was used to produce a positron emitter distribution, which was parameterized and then used as the source distribution inside a water-filled cylinder for EGS4 simulations of a PET system. Design optimization studies were performed as a function of crystal type and size, system timing resolution, scanner angular coverage and number of positron emitter decays. Data analysis was performed to measure the accuracy of the reconstructed positron emitter distribution as well as the range of the positron emitter distribution. We simulated scanners with varying crystal sizes (2-4 mm) and type (LYSO and LaBr3) and our results indicate that 4 mm wide LYSO or LaBr3 crystals (resulting in 4-5 mm spatial resolution) are adequate; for a full-ring, non-TOF scanner we predict a low bias (<0.6 mm) and a good precision (<1 mm) in the

  5. Structure-function relationships of bacterial and enzymatically produced reuterans and dextran in sourdough bread baking application.

    PubMed

    Chen, Xiao Yan; Levy, Clemens; Gänzle, Michael G

    2016-12-19

    Exopolysaccharides from lactic acid bacteria may improve texture and shelf life of bread. The effect of exopolysaccharides on bread quality, however, depends on properties of the EPS and the EPS producing strain. This study investigated structure-function relationships of EPS in baking application. The dextransucrase DsrM and the reuteransucrase GtfA were cloned from Weissella cibaria 10M and Lactobacillus reuteri TMW1.656, respectively, and heterologously expressed in Escherichia coli. Site-directed mutagenesis of GtfA was generates reuterans with different glycosidic bonds. NMR spectrum indicated reuteranPI, reuteranNS and reuteranPINS produced by GtfA-V1024P:V1027I, GtfA-S1135N:A1137S and GtfA-V1024P:V1027I:S1135N:A1137S, respectively, had a higher proportion of α-(1→4) linkages when compared to reuteran. ReuteranNS has the lowest molecular weight as measured by asymmetric flow-field-flow fractionation. The reuteransucrase negative mutant L. reuteri TMW1.656ΔgtfA was generated as EPS-negative derivative of L. reuteri TMW1.656. Cell counts, pH, and organic acid levels of sourdough fermented with L. reuteri TMW1.656 and TMW1.656ΔgtfA were comparable. Reuteran produced by L. reuteri TMW1.656 during growth in sourdough and reuteran produced ex situ by GtfA-ΔN had comparable effects on bread volume and crumb hardness. Enzymatically produced dextran improved volume and texture of wheat bread, and of bread containing 20% rye flour. ReuteranNS but not reuteranPI or reuteran was as efficient as dextran in enhancing wheat bread volume and texture. Overall, reuteran linkage type and molecular weight are determinants of EPS effects on bread quality. This study established a valuable method to elucidate structure-function relationships of glucans in baking applications.

  6. In situ chemical fixation of arsenic-contaminated soils: Anexperimental study

    SciTech Connect

    Yang, Li; Donahoe, Rona J.; Redwine, James C.

    2007-03-27

    This paper reports the results of an experimentalstudytesting a low-cost in situ chemical fixation method designed to reclaimarsenic-contaminated subsurface soils. Subsurface soils from severalindustrial sites in southeastern U.S. were contaminated with arsenicthrough heavy application of herbicide containing arsenic trioxide. Themean concentrations of environmentally available arsenic in soilscollected from the two study sites, FW and BH, are 325 mg/kg and 900mg/kg, respectively. The soils are sandy loams with varying mineralogicaland organic contents. The previous study [Yang L, Donahoe RJ. The form,distribution and mobility of arsenic in soils contaminated by arsenictrioxide, at sites in Southeast USA. Appl Geochem 2007;22:320 341]indicated that a large portion of the arsenic in both soils is associatedwith amorphous aluminum and iron oxyhydroxides and shows very slowrelease against leaching by synthetic precipitation. The soil's amorphousaluminum and iron oxyhydroxides content was found to have the mostsignificant effect on its ability to retain arsenic.Based on thisobservation, contaminated soils were reacted with different treatmentsolutions in an effort to promote the formation of insolublearsenic-bearing phases and thereby decrease the leachability of arsenic.Ferrous sulfate, potassium permanganate and calcium carbonate were usedas the reagents for the chemical fixation solutions evaluated in threesets of batch experiments: (1) FeSO4; (2) FeSO4 and KMnO4; (3) FeSO4,KMnO4 and CaCO3. The optimum treatment solutions for each soil wereidentified based on the mobility of arsenic during sequential leaching oftreated and untreated soils using the fluids described in EPA Method 1311[USEPA. Method 1311: toxicity characteristic leaching procedure. Testmethods for evaluating solid waste, physical/chemical methods. 3rd ed.Washington, DC: U.S. Environmental Protection Agency, Office of SolidWaste. U.S. Government Printing Office; 1992]toxic characteristicsleaching

  7. In situ spectroscopic applications to the study of rechargeable lithium batteries. Final report

    SciTech Connect

    Barbour, R.; Kim, Sunghyun; Tryk, D.; Scherson, D.A.

    1993-08-01

    In situ attenuated total reflection Fourier transform infrared spectroscopy (ATR/FTIR) has been employed to examine the reactivity of lithium toward polyethylene oxide (PEO) at ca. 60{degree}C. Uncertainties regarding the cleanliness of the Li surfaces were, minimized by electrodepositing a film of metallic Li directly onto a thin layer of gold (ca. 60 {Angstrom}) vapor deposited on a Ge ATR optical element during the spectroscopic measurements. The ATR/FTIR features observed upon stripping the Li layer were consistent with the formation of alkoxide-type moieties resulting from the Li-induced cleavage of the ether-type functionalities. Electronic and structural aspects of the electrochemical insertion of lithium from non-aqueous electroyltes into FeS{sub 2} have been investigated using in situ Fe K-edge X-ray absorption fine structure (XAFS). The results obtained indicate that the incorporation of Li{sup +} in the pyrite lattice brings about a marked decrease in the amplitude of the extended XAFS (EXAFS) oscillations, particularly for shells associated with distant atoms and a rounding of the, X-ray absorption near edge structure (XANES) region. An analysis of the EXAFS spectra yielded a value for the FeS distance of 2.29 {plus_minus} 0.02 {Angstrom}. On this basis and additional in situ room temperature {sup 57}Fe Mossbauer effect spectroscopy data for the same system it has been proposed that the electrically formed material involves a highly disordered (possibly amorphous) form of Fe{sub l-x}S (with Li+ counterbalancing the charge).

  8. In situ Gel of Metoprolol Tartrate: Physicochemical Characterization, In vitro Diffusion and Histological Studies

    PubMed Central

    Khan, S.; Gajbhiye, C.; Singhavi, D. J.; Yeole, P.

    2012-01-01

    The purpose of the present investigation was to prepare an intranasal in situ gel with increased nasal residence time in order to improve bioavailability of metoprolol tartrate. The in situ gel systems containing carbopol, hydroxypropyl methylcellulose K4M and K15M in different concentrations were prepared. The samples were characterized for viscosity, rheological behavior, gelation behavior, gel strength, and mucoadhesion. The formulations F10 (0.4% w/v carbopol, 1% w/v hydroxylpropyl methylcellulose K15M) and F13 (0.3% w/v carbopol, 1% w/v hydroxypropyl methylcellulose K15M) showed gel strength of 40.33±0.47 and 43.00±1.41, respectively, and mucoadhesion strength 31.48±0.14×103 and 32.12±0.05×103 dyne/cm2, respectively. In vitro release profiles showed initial burst followed by slow release. F10 and F13 released 88.08±0.98 and 91.18±1.09% drug in 8 h. R2 value for F10 (0.9953) and F13 (0.9942) was maximum for Higuchi, showing mixed order kinetics while n value obtained on treatment with Korsemayer Pappas equation were near to 0.5, suggesting release by fickian diffusion mechanism. The nasal permeability of formulations F10 and F13 were found to be 0.057 and 0.063 cm/s, respectively. Histopathological examination revealed slight degeneration of nasal epithelium with increased vascularity by F10 but no inflammation by formulation F13. Thus, a pH triggered in situ gel system containing low concentration (0.3% w/v) of carbopol demonstrated sustained release of metoprolol tartrate without any destructive effect on the mucosa. PMID:23798784

  9. In situ EPR studies of reaction pathways in Titania photocatalyst-promoted alkylation of alkenes.

    PubMed

    Rhydderch, Shona; Howe, Russell F

    2015-03-03

    In situ EPR spectroscopy at cryogenic temperatures has been used to observe and identify paramagnetic species produced when titania is irradiated in the presence of reactants used in the photocatalytic alkylation of maleimide with t-butyl carboxylic acid or phenoxyacetic acid. It is shown that maleimide acts as an acceptor of conduction band electrons. Valence band holes oxidise t-butyl carboxylic acid to the t-butyl radical and phenoxyacetic acid to the phenoxyacetic acid radical cation. In the presence of maleimide, the phenoxymethyl radical is formed from phenoxyacetic acid. The relevance of these observations to the mechanisms of titania photocatalyst-promoted alkylation of alkenes is discussed.

  10. An in situ study of resin-assisted solvothermal metal-organic framework synthesis

    NASA Astrophysics Data System (ADS)

    Moorhouse, Saul J.; Wu, Yue; O'Hare, Dermot

    2016-04-01

    A newly developed in situ monochromatic high-energy X-ray diffraction setup was used to investigate the synthesis of MOFs using cation-impregnated polymer resin beads as a ion source. The Co-NDC-DMF (NDC=2,6-naphthalenedicarboxylate; DMF=dimethylformamide) system was investigated, a system which is known to produce at least three distinct frameworks. It was found that the resin-assisted synthesis results in the preferential formation of a topology previously impossible to synthesise in bulk, while the comparable nitrate-salt synthesis appeared to form an alternative phases. It was also found that the resin-assisted synthesis is highly diffusion-controlled.

  11. F4TCNQ-Induced Exciton Quenching Studied by Using in-situ Photoluminescence Measurements

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Lu, Min; Wu, Bo; Hou, Xiao-Yuan

    2012-09-01

    The role of F4TCNQ as an exciton quenching material in thin organic light-emitting films is investigated by means of in situ photoluminescence measurements. C60 was used as another quenching material in the experiment for comparison, with Alq3 as a common organic light-emitting material. The effect of the growth sequence of the materials on quenching was also examined. It is found that the radius of Förster energy transfer between F4TCNQ and Alq3 is close to 0 nm and Dexter energy transfer dominates in the quenching process.

  12. Study of inorganic fullerenes and carbon nanotubes by in situ Raman tribometry

    NASA Astrophysics Data System (ADS)

    Joly-Pottuz, L.; Martin, J. M.; Belin, M.; Dassenoy, F.; Montagnac, G.; Reynard, B.

    2007-10-01

    Nanoparticles such as inorganic fullerenes of metal dichalcogenides or carbon nanotubes have been recently used as lubricant additives and they present excellent tribological properties. Raman spectroscopy is a useful technique to follow modification of these two structures. We developed an original tribometer able to perform in situ Raman analyses during sliding steel on a sapphire flat. These analyses gave unique information on real-time structural changes of nanoparticles inside the contact area: inorganic fullerenes are tribologically active by a progressive exfoliation process and carbon nanotubes is changed to amorphous carbon. Lubrication mechanism of these particles are explained in the light of analytical results.

  13. In situ real-time studies of nickel silicide phase formation

    NASA Astrophysics Data System (ADS)

    Tinani, Manisha

    2000-10-01

    Metal silicides have attracted considerable attention in recent years as low resistivity metal contact and interconnect materials in microelectronics. Historically, polycrystalline silicon has been used as the gate contact material. However, as device size decreases, the higher resistance of polycrystalline silicon can degrade device performance. Metal silicides provide low metal like resistivities and high temperature stability. Ideal silicides for practical applications need to have stable phases, low processing temperatures and mechanical compatibility with silicon, in order to reduce defects and roughness at the silicon-silicide interface. NiSi, one of the nickel silicide phases, fulfills all these criteria. It has a resistivity of 14muO-cm, and a large processing temperature window (350--750°C). NiSi actually surpasses other commonly used silicides such as COSi2 and TiSi2 1 in these properties, while avoiding problems generally faced with these silicides2. Prior to the use of NiSi, its formation mechanism must be understood. The objective of this research is to develop analytical procedures to monitor phase transformations, in our case NiSi, in real-time, using non-destructive techniques. To this end, we studied the formation of NiSi films on Si using Rutherford Backscattering spectrometry, atomic force microscopy, X-ray photoelectron spectroscopy, and real-time single wavelength and spectroscopic ellipsometry. Several nickel silicide phases (Ni2Si, NiSi, NiSi2), with different properties, form in various temperature ranges below 1000°C. Three phases, Ni2Si, NiSi, NiSi2, were identified in this temperature range, and their optical databases in the 2--4 eV range were established. We demonstrated that we can identify the phases and the extent of phase formation from optical data obtained via spectroscopic ellipsometry in real-time, and modeled the data using the optical databases established. We have also observed the onset of agglomeration of the silicide for

  14. [Clustered regularly interspaced short palindromic repeats: structure, function and application--a review].

    PubMed

    Cui, Yujun; Li, Yanjun; Yan, Yanfeng; Yang, Ruifu

    2008-11-01

    CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats), the basis of spoligotyping technology, can provide prokaryotes with heritable adaptive immunity against phages' invasion. Studies on CRISPR loci and their associated elements, including various CAS (CRISPR-associated) proteins and leader sequences, are still in its infant period. We introduce the brief history', structure, function, bioinformatics research and application of this amazing immunity system in prokaryotic organism for inspiring more scientists to find their interest in this developing topic.

  15. In-situ spectroscopic ellipsometry study of copper selective-area atomic layer deposition on palladium

    SciTech Connect

    Jiang, Xiaoqiang; Wang, Han; Qi, Jie; Willis, Brian G.

    2014-07-01

    Selective area copper atomic layer deposition on palladium seed layers has been investigated with in-situ real-time spectroscopic ellipsometry to probe the adsorption/desorption and reaction characteristics of individual deposition cycles. The reactants are copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) vapor and hydrogen gas. Self-limiting atomic layer deposition was observed in the temperature range of 135–230 °C in a low pressure reactor. Under optimal conditions, growth occurs selectively on palladium and not on silicon dioxide or silicon nitride layers. Based on in-situ ellipsometry data and supporting experiments, a new mechanism for growth is proposed. In the proposed mechanism, precursor adsorption is reversible, and dissociatively adsorbed hydrogen are the stable surface intermediates between growth cycles. The mechanism is enabled by continuous diffusion of palladium from the seed layer into the deposited copper film and strong H* binding to palladium sites. Less intermixing can be obtained at low growth temperatures and short cycle times by minimizing Cu/Pd inter-diffusion.

  16. Al2O3 on Black Phosphorus by Atomic Layer Deposition: An in Situ Interface Study.

    PubMed

    Zhu, Hui; McDonnell, Stephen; Qin, Xiaoye; Azcatl, Angelica; Cheng, Lanxia; Addou, Rafik; Kim, Jiyoung; Ye, Peide D; Wallace, Robert M

    2015-06-17

    In situ "half cycle" atomic layer deposition (ALD) of Al2O3 was carried out on black phosphorus ("black-P") surfaces with modified phosphorus oxide concentrations. X-ray photoelectron spectroscopy is employed to investigate the interfacial chemistry and the nucleation of the Al2O3 on black-P surfaces. This work suggests that exposing a sample that is initially free of phosphorus oxide to the ALD precursors does not result in detectable oxidation. However, when the phosphorus oxide is formed on the surface prior to deposition, the black-P can react with both the surface adventitious oxygen contamination and the H2O precursor at a deposition temperature of 200 °C. As a result, the concentration of the phosphorus oxide increases after both annealing and the atomic layer deposition process. The nucleation rate of Al2O3 on black-P is correlated with the amount of oxygen on samples prior to the deposition. The growth of Al2O3 follows a "substrate inhibited growth" behavior where an incubation period is required. Ex situ atomic force microscopy is also used to investigate the deposited Al2O3 morphologies on black-P where the Al2O3 tends to form islands on the exfoliated black-P samples. Therefore, surface functionalization may be needed to get a conformal coverage of Al2O3 on the phosphorus oxide free samples.

  17. A practical guide for the study of human and murine sebaceous glands in situ.

    PubMed

    Hinde, Eleanor; Haslam, Iain S; Schneider, Marlon R; Langan, Ewan A; Kloepper, Jennifer E; Schramm, Carolin; Zouboulis, Christos C; Paus, Ralf

    2013-10-01

    The skin of most mammals is characterised by the presence of sebaceous glands (SGs), whose predominant constituent cell population is sebocytes, that is, lipid-producing epithelial cells, which develop from the hair follicle. Besides holocrine sebum production (which contributes 90% of skin surface lipids), multiple additional SG functions have emerged. These range from antimicrobial peptide production and immunomodulation, via lipid and hormone synthesis/metabolism, to the provision of an epithelial progenitor cell reservoir. Therefore, in addition to its involvement in common skin diseases (e.g. acne vulgaris), the unfolding diversity of SG functions, both in skin health and disease, has raised interest in this integral component of the pilosebaceous unit. This practical guide provides an introduction to SG biology and to relevant SG histochemical and immunohistochemical techniques, with emphasis placed on in situ evaluation methods that can be easily employed. We propose a range of simple, established markers, which are particularly instructive when addressing specific SG research questions in the two most commonly investigated species in SG research, humans and mice. To facilitate the development of reproducible analysis techniques for the in situ evaluation of SGs, this methods review concludes by suggesting quantitative (immuno-)histomorphometric methods for standardised SG evaluation.

  18. In situ ATR-FTIR study of the early stages of fly ash geopolymer gel formation.

    PubMed

    Rees, Catherine A; Provis, John L; Lukey, Grant C; van Deventer, Jannie S J

    2007-08-14

    The kinetics of geopolymer formation are monitored using a novel in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopic technique. Reaction rates are determined from the intensity variation of the bands related to the geopolymer gel network and the unreacted fly ash particles. Comparison with deuterated geopolymer samples provides critical information regarding peak assignments. An initial induction (lag) period is observed to occur for hydroxide-activated geopolymers, followed by gel evolution according to an approximately linear reaction profile. The length of the lag period is reduced by increasing the concentration of NaOH. An increase in the rate of network formation also occurs with increasing NaOH concentration up to a maximum point, beyond which an increased NaOH concentration leads to a reduced rate of network formation. This trend is attributed to the competing effects of increased alkalinity and stronger ion pairing with an increase in NaOH concentration. In situ analysis also shows that the rate of fly ash dissolution is similar for all moderate- to high-alkali geopolymer slurries, which is attributed to the very highly water-deficient nature of these systems and is contrary to predictions from classical glass dissolution chemistry. This provides for the first time detailed kinetic information describing fly ash geopolymer formation kinetics.

  19. NUMERICAL STUDY ON IN SITU PROMINENCE FORMATION BY RADIATIVE CONDENSATION IN THE SOLAR CORONA

    SciTech Connect

    Kaneko, T.; Yokoyama, T.

    2015-06-10

    We propose an in situ formation model for inverse-polarity solar prominences and demonstrate it using self-consistent 2.5 dimensional MHD simulations, including thermal conduction along magnetic fields and optically thin radiative cooling. The model enables us to form cool dense plasma clouds inside a flux rope by radiative condensation, which is regarded as an inverse-polarity prominence. Radiative condensation is triggered by changes in the magnetic topology, i.e., formation of the flux rope from the sheared arcade field, and by thermal imbalance due to the dense plasma trapped inside the flux rope. The flux rope is created by imposing converging and shearing motion on the arcade field. Either when the footpoint motion is in the anti-shearing direction or when heating is proportional to local density, the thermal state inside the flux rope becomes cooling-dominant, leading to radiative condensation. By controlling the temperature of condensation, we investigate the relationship between the temperature and density of prominences and derive a scaling formula for this relationship. This formula suggests that the proposed model reproduces the observed density of prominences, which is 10–100 times larger than the coronal density. Moreover, the time evolution of the extreme ultraviolet emission synthesized by combining our simulation results with the response function of the Solar Dynamics Observatory Atmospheric Imaging Assembly filters agrees with the observed temporal and spatial intensity shift among multi-wavelength extreme ultraviolet emission during in situ condensation.

  20. Structure-Function-Property-Design Interplay in Biopolymers: Spider Silk

    PubMed Central

    Tokareva, Olena; Jacobsen, Matthew; Buehler, Markus; Wong, Joyce; Kaplan, David L.

    2013-01-01

    Spider silks have been a focus of research for almost two decades due to their outstanding mechanical and biophysical properties. Recent advances in genetic engineering have led to the synthesis of recombinant spider silks, thus helping to unravel a fundamental understanding of structure-function-property relationships. The relationships between molecular composition, secondary structures, and mechanical properties found in different types of spider silks are described, along with a discussion of artificial spinning of these proteins and their bioapplications, including the role of silks in biomineralization and fabrication of biomaterials with controlled properties. PMID:23962644

  1. Moments of the neutron g₂ structure function at intermediate Q²

    SciTech Connect

    Solvignon-Slifer, Patricia H.

    2015-07-15

    We present new experimental results of the ³He spin structure function g₂ in the resonance region at Q² values between 1.2 and 3.0 (GeV/c)². Spin dependent moments of the neutron were then extracted.Our main result, the inelastic contribution to the neutron d₂ matrix element, was found to be small (Q²) = 2.4 (GeV/c)² and in agreement with the Lattice QCD calculation. The Burkhardt-Cottingham sum rule for ³He neutron was tested with the measured data and using the Wandzura-Wilczek relation for the low x unmeasured region.

  2. In Situ Laser Crystallization of Amorphous Silicon for TFT Applications: Controlled Ultrafast Studies in the Dynamic TEM

    SciTech Connect

    Taheri, M; Teslich, N; Lu, J P; Morgan, D; Browning, N

    2008-02-08

    An in situ method for studying the role of laser energy on the microstructural evolution of polycrystalline Si is presented. By monitoring both laser energy and microstructural evolution simultaneously in the dynamic transmission electron microscope, information on grain size and defect concentration can be correlated directly with processing conditions. This proof of principle study provides fundamental scientific information on the crystallization process that has technological importance for the development of thin film transistors. In conclusion, we successfully developed a method for studying UV laser processing of Si films in situ on nanosecond time scales, with ultimate implications for TFT application improvements. In addition to grain size distribution as a function of laser energy density, we found that grain size scaled with laser energy in general. We showed that nanosecond time resolution allowed us to see the nucleation and growth front during processing, which will help further the understanding of microstructural evolution of poly-Si films for electronic applications. Future studies, coupled with high resolution TEM, will be performed to study grain boundary migration, intergranular defects, and grain size distribution with respect to laser energy and adsorption depth.

  3. Spatially-resolved in-situ structural study of organic electronic devices with nanoscale resolution: the plasmonic photovoltaic case study.

    PubMed

    Paci, B; Bailo, D; Albertini, V Rossi; Wright, J; Ferrero, C; Spyropoulos, G D; Stratakis, E; Kymakis, E

    2013-09-14

    A novel high spatial resolution synchrotron X-ray diffraction stratigraphy technique has been applied in-situ to an integrated plasmonic nanoparticle-based organic photovoltaic device. This original approach allows for the disclosure of structure-property relations linking large scale organic devices to length scales of local nano/hetero structures and interfaces between the different components.

  4. Studies of ferroelectric heterostructure thin films, interfaces, and device-related processes via in situ analytical techniques.

    SciTech Connect

    Aggarwal, S.; Auciello, O.; Dhote, A. M.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A.; Krauss, A. R.; Muller, A. H.; Ramesh, R.

    1999-06-29

    The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMS) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and device processes relevant to device development. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed. Direct imaging of ferroelectric domains under applied electric fields can provide valuable information to understand domain dynamics in ferroelectric films. We discuss results of piezoresponse scanning force microscopy (SFM) imaging for nanoscale studies of polarization reversal and retention loss in Pb(Zr{sub x}Ti{sub 1{minus}x})O{sub 3} (PZT)-based capacitors. Another powerful technique suitable for in situ, real-time characterization of film growth processes and ferroelectric film-based device operation is based on synchrotrons X-ray scattering, which is currently being implemented at Argonne National Laboratory.

  5. p53 Proteoforms and Intrinsic Disorder: An Illustration of the Protein Structure-Function Continuum Concept.

    PubMed

    Uversky, Vladimir N

    2016-11-10

    Although it is one of the most studied proteins, p53 continues to be an enigma. This protein has numerous biological functions, possesses intrinsically disordered regions crucial for its functionality, can form both homo-tetramers and isoform-based hetero-tetramers, and is able to interact with many binding partners. It contains numerous posttranslational modifications, has several isoforms generated by alternative splicing, alternative promoter usage or alternative initiation of translation, and is commonly mutated in different cancers. Therefore, p53 serves as an important illustration of the protein structure-function continuum concept, where the generation of multiple proteoforms by various mechanisms defines the ability of this protein to have a multitude of structurally and functionally different states. Considering p53 in the light of a proteoform-based structure-function continuum represents a non-canonical and conceptually new contemplation of structure, regulation, and functionality of this important protein.

  6. Proton and deuteron spin structure function measurements in the resonance region

    SciTech Connect

    F.R. Wesselmann

    2003-07-01

    The RSS collaboration has measured the spin structure functions of the proton and the deuteron at Jefferson Lab using the Hall C HMS spectrometer, a polarized electron beam and a polarized solid target. The asymmetries A and A were measured in the region of the nucleon resonances (0.82 GeV < W < 1.98 GeV) at an average four momentum transfer of Q2 = 1.3 GeV2. The extracted spin structure functions and their kinematic dependence will make a significant contribution in the study of higher-twist effects and polarized duality tests. A description of the experiment and the latest findings of the analysis will be presented.

  7. Twist expansion of Drell-Yan structure functions in color dipole approach

    NASA Astrophysics Data System (ADS)

    Motyka, Leszek; Sadzikowski, Mariusz; Stebel, Tomasz

    2015-05-01

    The forward Drell-Yan process at the LHC probes the proton structure at a very small Bjorken- x and moderate hard scales. In this kinematical domain higher twist effects may be significant and introduce sizeable corrections to the standard leading twist description. We study the forward Drell-Yan process beyond the leading twist approximation within the color dipole model framework that incorporates multiple scattering effects. We derive the Mellin representation of the forward Drell-Yan impact factors for fully differential cross-sections. These results combined with the color dipole cross-section of the saturation model are used to perform the twist expansion of the Drell-Yan structure functions at arbitrary transverse momentum q T of the Drell-Yan pair and also of the structure functions integrated over q T . We also investigate the Lam-Tung relation, find that it is broken at twist 4 and provide explicit estimates for the breaking term.

  8. From sequence and forces to structure, function, and evolution of intrinsically disordered proteins.

    PubMed

    Forman-Kay, Julie D; Mittag, Tanja

    2013-09-03

    Intrinsically disordered proteins (IDPs), which lack persistent structure, are a challenge to structural biology due to the inapplicability of standard methods for characterization of folded proteins as well as their deviation from the dominant structure/function paradigm. Their widespread presence and involvement in biological function, however, has spurred the growing acceptance of the importance of IDPs and the development of new tools for studying their structure, dynamics, and function. The interplay of folded and disordered domains or regions for function and the existence of a continuum of protein states with respect to conformational energetics, motional timescales, and compactness are shaping a unified understanding of structure-dynamics-disorder/function relationships. In the 20(th) anniversary of Structure, we provide a historical perspective on the investigation of IDPs and summarize the sequence features and physical forces that underlie their unique structural, functional, and evolutionary properties.

  9. Structure-function relationship in the antifreeze activity of synthetic alanine-lysine antifreeze polypeptides.

    PubMed

    Wierzbicki, A; Knight, C A; Rutland, T J; Muccio, D D; Pybus, B S; Sikes, C S

    2000-01-01

    Recently antifreeze proteins (AFP) have been the subject of many structure-function relationship studies regarding their antifreeze activity. Attempts have been made to elucidate the structure-function relationship by various amino acid substitutions, but to our knowledge there has been no successful from first principles design of a polypeptide that would bind to designated ice planes along a specific direction. In this paper we show the results of our first attempt on an entirely de novo design of an alanine-lysine-rich antifreeze polypeptide. This 43 residue alanine-lysine peptide exhibits characteristic nonequilibrium freezing point depression and binds to the designated (210) planes of ice along the [122] vector. The structural and thermodynamic properties of this polypeptide were determined using circular dichroism spectroscopy and its nonequilibrium antifreeze properties were investigated using an ice-etching method and nanoliter osmometry.

  10. From Sequence and Forces to Structure, Function and Evolution of Intrinsically Disordered Proteins

    PubMed Central

    Forman-Kay, Julie D.; Mittag, Tanja

    2015-01-01

    Intrinsically disordered proteins (IDPs), which lack persistent structure, are a challenge to structural biology due to the inapplicability of standard methods for characterization of folded proteins as well as their deviation from the dominant structure/function paradigm. Their widespread presence and involvement in biological function, however, has spurred the growing acceptance of the importance of IDPs and the development of new tools for studying their structure, dynamics and function. The interplay of folded and disordered domains or regions for function and the existence of a continuum of protein states with respect to conformational energetics, motional timescales and compactness is shaping a unified understanding of structure-dynamics-disorder/function relationships. On the 20th anniversary of this journal, Structure, we provide a historical perspective on the investigation of IDPs and summarize the sequence features and physical forces that underlie their unique structural, functional and evolutionary properties. PMID:24010708

  11. Heterogeneously catalysed partial oxidation of acrolein to acrylic acid--structure, function and dynamics of the V-Mo-W mixed oxides.

    PubMed

    Kampe, Philip; Giebeler, Lars; Samuelis, Dominik; Kunert, Jan; Drochner, Alfons; Haass, Frank; Adams, Andreas H; Ott, Joerg; Endres, Silvia; Schimanke, Guido; Buhrmester, Thorsten; Martin, Manfred; Fuess, Hartmut; Vogel, Herbert

    2007-07-21

    The major objective of this research project was to reach a microscopic understanding of the structure, function and dynamics of V-Mo-(W) mixed oxides for the partial oxidation of acrolein to acrylic acid. Different model catalysts (from binary and ternary vanadium molybdenum oxides up to quaternary oxides with additional tungsten) were prepared via a solid state preparation route and hydrochemical preparation of precursors by spray-drying or crystallisation with subsequent calcination. The phase composition was investigated ex situ by XRD and HR-TEM. Solid state prepared samples are characterised by crystalline phases associated to suitable phase diagrams. Samples prepared from crystallised and spray-dried precursors show crystalline phases which are not part of the phase diagram. Amorphous or nanocrystalline structures are only found in tungsten doped samples. The kinetics of the partial oxidation as well as the catalysts' structure have been studied in situ by XAS, XRD, temperature programmed reaction and reduction as well as by a transient isotopic tracing technique (SSITKA). The reduction and re-oxidation kinetics of the bulk phase have been evaluated by XAS. A direct influence not only of the catalysts' composition but also of the preparation route is shown. Altogether correlations are drawn between structure, oxygen dynamics and the catalytic performance in terms of activity, selectivity and long-term stability. A model for the solid state behaviour under reaction conditions has been developed. Furthermore, isotope exchange experiments provided a closer image of the mechanism of the selective acrolein oxidation. Based on the in situ characterisation in combination with micro kinetic modelling a detailed reaction model which describes the oxygen exchange and the processes at the catalyst more precisely is discussed.

  12. In-situ study of crystallization kinetics in ternary bulk metallic glass alloys with different glass forming abilities

    DOE PAGES

    Lan, Si; Wei, Xiaoya; Zhou, Jie; ...

    2014-11-18

    In-situ transmission electron microcopy and time-resolved neutron diffraction were used to study crystallization kinetics of two ternary bulk metallic glasses during isothermal annealing in the supercooled liquid region. It is found that the crystallization of Zr56Cu36Al8, an average glass former, follows continuous nucleation and growth, while that of Zr46Cu46Al8, a better glass former, is characterized by site-saturated nucleation, followed by slow growth. Possible mechanisms for the observed differences and the relationship to the glass forming ability are discussed.

  13. A study to identify and compare airborne systems for in-situ measurements of launch vehicle effluents

    NASA Technical Reports Server (NTRS)

    Thomas, T. J.; Chace, A. S.

    1974-01-01

    An in-situ system for monitoring the concentration of HCl, CO, CO2, and Al2O3 in the cloud of reaction products that form as a result of a launch of solid propellant launch vehicle is studied. A wide array of instrumentation and platforms are reviewed to yield the recommended system. An airborne system suited to monitoring pollution concentrations over urban areas for the purpose of calibrating remote sensors is then selected using a similar methodology to yield the optimal configuration.

  14. In-situ optical transmission electron microscope study of exciton phonon replicas in ZnO nanowires by cathodoluminescence

    SciTech Connect

    Yang, Shize; Tian, Xuezeng; Wang, Lifen; Wei, Jiake; Qi, Kuo; Li, Xiaomin; Xu, Zhi E-mail: xdbai@iphy.ac.cn Wang, Wenlong; Zhao, Jimin; Bai, Xuedong E-mail: xdbai@iphy.ac.cn; Wang, Enge E-mail: xdbai@iphy.ac.cn

    2014-08-18

    The cathodoluminescence spectrum of single zinc oxide (ZnO) nanowires is measured by in-situ optical Transmission Electron Microscope. The coupling between exciton and longitudinal optical phonon is studied. The band edge emission varies for different excitation spots. This effect is attributed to the exciton propagation along the c axis of the nanowire. Contrary to free exciton emission, the phonon replicas are well confined in ZnO nanowire. They travel along the c axis and emit at the end surface. Bending strain increases the relative intensity of second order phonon replicas when excitons travel along the c-axis.

  15. Novel application of imaging surface plasmon resonance for in situ studies of the surface exploration of marine organisms.

    PubMed

    Andersson, Olof; Ekblad, Tobias; Aldred, Nick; Clare, Anthony S; Liedberg, Bo

    2009-12-01

    The surface interactions of exploring cyprids of the barnacle Semibalanus balanoides were studied in situ using imaging surface plasmon resonance. It was demonstrated how the deposition of a proteinaceous adhesive could be followed in real time as the cyprids explored and temporarily attached to a surface. Furthermore, the amount of protein left on the surface when the cyprids moved on could be quantified. Clear differences were demonstrated between an oligo(ethyleneglycol) coated surface and a bare gold substrate. It is anticipated that this technique will be a valuable tool in the development of novel surface chemistries that can prevent biofouling.

  16. In situ spectroscopic study of the plastic deformation of amorphous silicon under nonhydrostatic conditions induced by indentation

    DOE PAGES

    Gerbig, Yvonne B.; Michaels, C. A.; Bradby, Jodie E.; ...

    2015-12-17

    Indentation-induced plastic deformation of amorphous silicon (a-Si) thin films was studied by in situ Raman imaging of the deformed contact region of an indented sample, employing a Raman spectroscopy-enhanced instrumented indentation technique (IIT). The occurrence and evolving spatial distribution of changes in the a-Si structure caused by processes, such as polyamorphization and crystallization, induced by indentation loading were observed. Furthermore, the obtained experimental results are linked with previously published work on the plastic deformation of a-Si under hydrostatic compression and shear deformation to establish a model for the deformation behavior of a-Si under indentation loading.

  17. Studies on parametric optimization for abrasive water jet machining of Al7075-TiB2 in-situ composite

    NASA Astrophysics Data System (ADS)

    Kavya, J. T.; Keshavamurthy, R.; Pradeep Kumar, G. S.

    2016-09-01

    The study focuses on optimization and determination of significant process parameter for Abrasive Water Jet Machining of Al7075-TiB2metal matrix composite. Al-TiB2 metal matrix composite is synthesized by stir casting using in-situ technique. Optimization of machining parameters is done using Taguchi's L25orthogonal array for the experimental trials, with cutting speed, stand-off distance and Abrasive Flow rate as input parameters at five different levels. Analysis Of Variance (ANOVA) method is used for identifying the effect of machining parameters on volumetric material removal rate, surface roughness and dimensional accuracy. Then the results are validated by conducting verification experiments.

  18. In situ high-resolution transmission electron microscopy study of interfacial reactions of Cu thin films on amorphous silicon

    NASA Astrophysics Data System (ADS)

    Lee, Sung Bo; Choi, Duck-Kyun; Phillipp, Fritz; Jeon, Kyung-Sook; Kim, Chang Kyung

    2006-02-01

    Interfacial reactions of Cu with amorphous silicon (a-Si) in the Cu /a-Si/glass system are studied by in situ high-resolution transmission electron microscopy at 550°C. Various Cu silicides, such as η-Cu3Si, Cu15Si4, and Cu5Si, and Cu particles are observed. The formation of the Cu particles can be attributed to a heating effect from electron beam irradiation. Around the Cu silicides, crystallization of a-Si occurs. Around the Cu particles, however, crystallization does not occur. Crystallization appears to be enhanced by Cu dissolved in a-Si.

  19. Application of in-situ electrical resistance measurements to the study of phase transformations in ferrous alloys

    NASA Astrophysics Data System (ADS)

    Kirbiš, Peter; Anžel, Ivan; Brunčko, Mihael

    2016-11-01

    Phase transformations have been studied in a variety of different steels with the use of "in situ" electrical resistance measurements. The results were evaluated by metallography of the initial and final microstructures and with consideration of data from the published literature. On this basis a good correlation has been established and it was shown that this method is suitable for such investigations. It even presents certain advantages, thus providing a more complete understanding of the physical metallurgy of steels. We out-lined the field in which the measurement of electrical resistance is particularly suitable and an example of processes that are difficult to monitor using other commonly used methods.

  20. In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental Study

    SciTech Connect

    Xie, Xianjun; Wang, Yanxin; Pi, Kunfu; Liu, Chongxuan; Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu

    2015-09-15

    In situ arsenic removal from groundwater by an iron coating method has great potential to be a cost effective and simple groundwater remediation technique, especially in rural and remote areas where groundwater is used as the main source of drinking water. The in situ arsenic removal technique was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions., Its effectiveness was then evaluated in an actual high-arsenic groundwater environment. The mechanism of arsenic removal by the iron coating was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, an electron microprobe, and Fourier transformation infrared spectroscopy. A 4-step alternative cycle aquifer iron coating method was developed. A continuous injection of 5 mmol/L FeSO4 and 2.5 mmol/L NaClO for 96 hours can create a uniform coating of crystalline goethite on the surface of quartz sand in the columns without causing clogging. At a flow rate of 0.45 cm/min of the injection reagents (vi), the time for arsenic (as Na2HAsO4) to pass through the iron-coated quartz sand column was approximately 35 hours, which was much longer than that for tracer fluorescein sodium (approximately 2 hours). The retardation factor of arsenic was 23, and its adsorption capacity was 0.11 mol As per mol Fe, leading to an excellent arsenic removal. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As (V) and Fe (II) reagents. When the arsenic content in the groundwater was 233 μg/L, the aqueous phase arsenic was completely removed with an arsenic adsorption of 0.05 mol As per mol Fe. Arsenic fixation resulted from a process of adsorption/co-precipitation, in which arsenic and iron likely formed the arsenic-bearing iron mineral phases with poor crystallinity by way of bidentate binuclear complexes. Thus, the high arsenic removal efficiency of the technique likely resulted from the

  1. Bioremediation of diesel-contaminated soils: evaluation of potential in situ techniques by study of bacterial degradation.

    PubMed

    Gallego, J L; Loredo, J; Llamas, J F; Vázquez, F; Sánchez, J

    2001-01-01

    The development of a simple laboratory methodology allows the implementation of in situ bioremediation of polluted soils with diesel fuel. In this investigation microbiological and chemical analyses and a suitable bioreactor design, were very useful for suggesting the best ways to improve biodegradation extents in a diesel-enriched soil. Biostimulation with inorganic nitrogen and phosphorus produced the best results in a simple bioreactor, with biodegradation extents higher than 90% after 45 days. Also, the addition of activated sludge from a domestic wastewater plant increased the degradation rate to a great extent. In both cases, microbiological studies showed the presence of Acinetobacter sp. degrading most of the hydrocarbons. Simultaneously, a diesel fuel release (approximately 400,000 l) was studied. Samples taken in polluted soil and water revealed that bacteria from the genus Acinetobacter were predominant. In plate studies, Acinetobacter colonies produced a whitish substance with the characteristics of a biosurfactant. Remarkably, the presence of this product was evident at the field site, both in the riverbanks and in the physical recovery plant. The study of the similarities between laboratory results and the diesel spill site strongly suggested that natural conditions at the field site allowed the implementation of in situ bioremediation after physical removal of LNAPL (light nonaqueous-phase liquids).

  2. Beamline electrostatic levitator for in situ high energy x-ray diffraction studies of levitated solids and liquids

    SciTech Connect

    Gangopadhyay, A.K.; Lee, G.W.; Kelto, K.F.; Rogers, J.R.; Goldman, A.I.; Robinson, D.S.; Rathz, T.J.; Hyers, R.W.

    2010-07-19

    Determinations of the phase formation sequence, crystal structures and the thermo-physical properties of materials at high temperatures are hampered by contamination from the sample container and environment. Containerless processing techniques, such as electrostatic (ESL), electromagnetic, aerodynamic, and acoustic levitation, are most suitable for these studies. An adaptation of ESL for in situ structural studies of a wide range of materials using high energy (30-130 keV) x rays at a synchrotron source is described here. This beamline ESL (BESL) allows the in situ determination of the atomic structures of equilibrium solid and liquid phases, undercooled liquids and time-resolved studies of solid-solid and liquid-solid phase transformations. The use of area detectors enables the rapid acquisition of complete diffraction patterns over a wide range (0.5-14 {angstrom}{sup -1}) of reciprocal space. The wide temperature range (300-2500 K), containerless processing environment under high vacuum (10{sup -7}-10{sup -8} Torr), and fast data acquisition capability, make BESL particularly well suited for phase stability studies of high temperature solids and liquids. An additional, but important, feature of BESL is the capability for simultaneous measurements of a host of thermo-physical properties including the specific heat, enthalpy of transformation, solidus and liquidus temperatures, density, viscosity, and surface tension, all on the same sample during the structural measurements.

  3. Structure-function scaling of bounded two-dimensional turbulence.

    PubMed

    Kramer, W; Keetels, G H; Clercx, H J H; van Heijst, G J F

    2011-08-01

    Statistical properties of forced two-dimensional turbulence generated in two different flow domains are investigated by numerical simulations. The considered geometries are the square domain and the periodic channel domain, both bounded by lateral no-slip sidewalls. The focus is on the direct enstrophy cascade range and how the statistical properties change in the presence of no-slip boundaries. The scaling exponents of the velocity and the vorticity structure functions are compared to the classical Kraichnan-Batchelor-Leith (KBL) theory, which assumes isotropy, homogeneity, and self-similarity for turbulence scales between the forcing and dissipation scale. Our investigation reveals that in the interior of the flow domain, turbulence can be considered statistically isotropic and locally homogeneous for the enstrophy cascade range, but it is weakly intermittent. However, the scaling of the vorticity structure function indicates a steeper slope for the energy spectrum than the KBL theory predicts. Near the walls the turbulence is strongly anisotropic at all flow scales.

  4. Functional materials discovery using energy-structure-function maps.

    PubMed

    Pulido, Angeles; Chen, Linjiang; Kaczorowski, Tomasz; Holden, Daniel; Little, Marc A; Chong, Samantha Y; Slater, Benjamin J; McMahon, David P; Bonillo, Baltasar; Stackhouse, Chloe J; Stephenson, Andrew; Kane, Christopher M; Clowes, Rob; Hasell, Tom; Cooper, Andrew I; Day, Graeme M

    2017-03-30

    Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal-organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy-structure-function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy-structure-function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties.

  5. Spin Structure Functions of the Proton - SANE experiment

    NASA Astrophysics Data System (ADS)

    Baghdasaryan, Hovhannes

    2012-03-01

    The Spin Asymmetries of the Nucleon Experiment (SANE) is a measurement of inclusive electron scattering parallel and near perpendicular double spin asymmetries from a proton target. The main goal of the experiment was to measure A and A80 and to extract the spin asymmetries of the proton A1^p, A2^p and the spin structure functions g1^p and g2^p. Using the Thomas Jefferson National Accelerator Facility's polarized electron beam and the University of Virginia's polarized frozen ammonia (^14NH3) target in Hall C, the experiment ran in 2009, collecting data in a Q^2 region from 2.5 to 6.5 GeV^2 and between Bjorken x of 0.3 and 0.8. Particle detection was accomplished using the Big Electron Telescope Array (BETA), a novel non-magnetic detector. The physics motivation for the experiment and a brief overview of the polarized target and the detector will be presented along with the analysis developed in order to extract the proton spin asymmetries and structure functions. Results will be presented.

  6. The fundamental structure function of oscillator noise models

    NASA Technical Reports Server (NTRS)

    Greenhall, C. A.

    1983-01-01

    Continuous-time models of oscillator phase noise x(t) usually have stationary nth differences, for some n. The covariance structure of such a model can be characterized in the time domain by the structure function: D sub n (t;gamma sub 1, gamma sub 2) = E delta (n) sub gamma sub 1 x(s+t) delta(n) sub gamma sub 2 x (s). Although formulas for the special case D sub 2 (0;gamma,gamma) (the Allan variance times 2 gamma(2)) exist for power-law spectral models, certain estimation problems require a more complete knowledge of (0). Exhibited is a much simpler function of one time variable, D(t), from which (0) can easily be obtained from the spectral density by uncomplicated integrations. Believing that D(t) is the simplest function of time that holds the same information as (0), D(t) is called the fundamental structure function. D(t) is computed for several power-law spectral models. Two examples are D(t) = K/t/(3) for random walk FM, D(t) = Kt(2) 1n/t/ for flicker FM. Then, to demonstrate its use, a BASIC program is given that computes means and variances of two Allan variance estimators, one of which incorporates a method of frequency drift estimation and removal.

  7. Emergent structure-function relations in emphysema and asthma.

    PubMed

    Winkler, Tilo; Suki, Béla

    2011-01-01

    Structure-function relationships in the respiratory system are often a result of the emergence of self-organized patterns or behaviors that are characteristic of certain respiratory diseases. Proper description of such self-organized behavior requires network models that include nonlinear interactions among different parts of the system. This review focuses on 2 models that exhibit self-organized behavior: a network model of the lung parenchyma during the progression of emphysema that is driven by mechanical force-induced breakdown, and an integrative model of bronchoconstriction in asthma that describes interactions among airways within the bronchial tree. Both models suggest that the transition from normal to pathologic states is a nonlinear process that includes a tipping point beyond which interactions among the system components are reinforced by positive feedback, further promoting the progression of pathologic changes. In emphysema, the progressive destruction of tissue is irreversible, while in asthma, it is possible to recover from a severe bronchoconstriction. These concepts may have implications for pulmonary medicine. Specifically, we suggest that structure-function relationships emerging from network behavior across multiple scales should be taken into account when the efficacy of novel treatments or drug therapy is evaluated. Multiscale, computational, network models will play a major role in this endeavor.

  8. Tensor-polarized structure functions: Tensor structure of deuteron in 2020's

    NASA Astrophysics Data System (ADS)

    Kumano, S.

    2014-10-01

    We explain spin structure for a spin-one hadron, in which there are new structure functions, in addition to the ones (F1, F2, g1, g2) which exist for the spin-1/2 nucleon, associated with its tensor structure. The new structure functions are b1, b2, b3, and b4 in deep inelastic scattering of a charged-lepton from a spin-one hadron such as the deuteron. Among them, twist- two functions are related by the Callan-Gross type relation b2 = 2xb1 in the Bjorken scaling limit. First, these new structure functions are introduced, and useful formulae are derived for projection operators of b1-4 from a hadron tensor Wμν. Second, a sum rule is explained for b1, and possible tensor-polarized distributions are discussed by using HERMES data in order to propose future experimental measurements and to compare them with theoretical models. A proposal was approved to measure b1 at the Thomas Jefferson National Accelerator Facility (JLab), so that much progress is expected for b1 in the near future. Third, formalisms of polarized proton-deuteron Drell-Yan processes are explained for probing especially tensor- polarized antiquark distributions, which were suggested by the HERMES data. The studies of the tensor-polarized structure functions will open a new era in 2020's for tensor-structure studies in terms of quark and gluon degrees of freedom, which are very different from ordinary descriptions in terms of nucleons and mesons.

  9. Development of customised environmental chambers for time-resolved in situ diffraction studies

    NASA Astrophysics Data System (ADS)

    Styles, M. J.; Riley, D. P.

    2010-11-01

    In an effort to mitigate the expense and broaden the applicability of customised environment chambers, researchers at the University of Melbourne and the Australian Nuclear Science and Technology Organisation (ANSTO) have designed and are currently commissioning a modular reaction chamber, capable of separating the necessities of diffraction methodologies from those of the desired sample environment. The In Situ Reaction Chamber (ISRC) abstracts many of the details intrinsic to the diffractometer, allowing users to design inexpensive environmental inserts that may be readily customised to their individual needs. The first insert to be developed for use with the ISRC is a high temperature furnace capable of providing an oxidising sample environment up to 1600°C.

  10. In Situ Real-Time Radiographic Study of Thin Film Formation Inside Rotating Hollow Spheres

    DOE PAGES

    Braun, Tom; Walton, Christopher C.; Dawedeit, Christoph; ...

    2016-02-03

    The hollow spheres with uniform coatings on the inner surface have applications in optical devices, time- or site-controlled drug release, heat storage devices, and target fabrication for inertial confinement fusion experiments. The fabrication of uniform coatings, which is often critical for the application performance, requires precise understanding and control over the coating process and its parameters. We report on in situ real-time radiography experiments that provide critical spatiotemporal information about the distribution of fluids inside hollow spheres during uniaxial rotation. Furthermore, image analysis and computer fluid dynamics simulations were used to explore the effect of liquid viscosity and rotational velocitymore » on the film uniformity. The data were then used to demonstrate the fabrication of uniform sol–gel chemistry derived porous polymer films inside 2 mm inner diameter diamond shells.« less

  11. In situ study of the initiation of hydrogen bubbles at the aluminium metal/oxide interface.

    PubMed

    Xie, De-Gang; Wang, Zhang-Jie; Sun, Jun; Li, Ju; Ma, Evan; Shan, Zhi-Wei

    2015-09-01

    The presence of excess hydrogen at the interface between a metal substrate and a protective oxide can cause blistering and spallation of the scale. However, it remains unclear how nanoscale bubbles manage to reach the critical size in the first place. Here, we perform in situ environmental transmission electron microscopy experiments of the aluminium metal/oxide interface under hydrogen exposure. It is found that once the interface is weakened by hydrogen segregation, surface diffusion of Al atoms initiates the formation of faceted cavities on the metal side, driven by Wulff reconstruction. The morphology and growth rate of these cavities are highly sensitive to the crystallographic orientation of the aluminium substrate. Once the cavities grow to a critical size, the internal gas pressure can become great enough to blister the oxide layer. Our findings have implications for understanding hydrogen damage of interfaces.

  12. Interdiffusion of long alcohols into thin ionomer films; In situ Neutron Reflectivity study

    NASA Astrophysics Data System (ADS)

    Etampawala, Thusitha; Ratnaweera, Dilru; Shrestha, Umesh; Perahia, Dvora; Cornelius, Christopher; Majewski, Jaroslaw

    2010-03-01

    Transport of solvents and ions within ionic polymers controls their many current and potential applications from energy related to drug delivery systems. The transport is determined by the phase structure and the interaction of the diffusing species with the polymers, coupled with interfacial effects. The current work presents the kinetics of penetration of long chain alcohols diffusing into rigid ionomer thin films formed by a rigid polyphenylene sulfonated ionomer, using in situ neutron reflectivity. The penetration of deuterated n-octanol and n-hexanol into ˜20nm thick films was followed as a function of time for different sulfonation levels of the polymer. As for shorter molecules, the diffusion process consists of two stages, a relatively fast one in which the film thickness increases linearly with time followed by a slow phase in which structural changes take place. With increasing sulfonation levels, the diffusion first increases and then decreases; a trend that is attributed to hydrophilic/hydrophobic balance.

  13. [Breast cancer in males: a study of 15 cases of pure ductal carcinoma in situ].

    PubMed

    Cutuli, B F; Florentz, P; Lacroze, M; Dilhuydy, J M; Allavena, C; De Lafontan, B; Resbeut, M; Campana, F; Graic, Y; Tortochaux, J

    1992-01-01

    Ductal carcinoma in situ of the breast is very rare in men, representing 0-7% of all male breast cancers. We analysed 15 cases from a retrospective multicentric series of 404 patients (3.7%). It occurs earlier than infiltrating carcinoma (mean age: 55 years), sometimes before 40 years of age. The main symptoms are bloody nipple discharge or retro areolar mass. Modified radical mastectomy constitutes the basic treatment. Lower axillary dissection can eventually be indicated in comedocarcinoma or in tumors larger than 25 mm. The main histologic subgroup is papillary carcinoma, pure or intracystic. As is the case in women, local recurrence, invasive or not, rarely occurs. Theoretically, the cure rate approaches 100%. However, as in all cases of breast cancer in men, an important number of deaths due to secondary cancer or intercurrent disease have been noted. Until now, no clear etiologic factors have been found.

  14. In situ study of defect migration kinetics in nanoporous Ag with enhanced radiation tolerance

    PubMed Central

    Sun, C.; Bufford, D.; Chen, Y.; Kirk, M. A.; Wang, Y. Q.; Li, M.; Wang, H.; Maloy, S. A.; Zhang, X.

    2014-01-01

    Defect sinks, such as grain boundaries and phase boundaries, have been widely accepted to improve the irradiation resistance of metallic materials. However, free surface, an ideal defect sink, has received little attention in bulk materials as surface-to-volume ratio is typically low. Here by using in situ Kr ion irradiation technique in a transmission electron microscope, we show that nanoporous (NP) Ag has enhanced radiation tolerance. Besides direct evidence of free surface induced frequent removal of various types of defect clusters, we determined, for the first time, the global and instantaneous diffusivity of defect clusters in both coarse-grained (CG) and NP Ag. Opposite to conventional wisdom, both types of diffusivities are lower in NP Ag. Such a surprise is largely related to the reduced interaction energy between isolated defect clusters in NP Ag. Determination of kinetics of defect clusters is essential to understand and model their migration and clustering in irradiated materials. PMID:24435181

  15. In situ nanoindentation study of plastic co-deformation in Al-TiN nanocomposites.

    PubMed

    Li, N; Wang, H; Misra, A; Wang, J

    2014-10-16

    We performed in situ indentation in a transmission electron microscope on Al-TiN multilayers with individual layer thicknesses of 50 nm, 5 nm and 2.7 nm to explore the effect of length scales on the plastic co-deformability of a metal and a ceramic. At 50 nm, plasticity was confined to the Al layers with easy initiation of cracks in the TiN layers. At 5 nm and below, cracking in TiN was suppressed and post mortem measurements indicated a reduction in layer thickness in both layers. The results demonstrate the profound size effect in enhancing plastic co-deformability in nanoscale metal-ceramic multilayers.

  16. In situ nanoindentation study of plastic Co-deformation in Al-TiN nanocomposites

    DOE PAGES

    Li, N.; Wang, H.; Misra, A.; ...

    2014-10-16

    We performed in situ indentation in a transmission electron microscope on Al-TiN multilayers with individual layer thicknesses of 50 nm, 5 nm and 2.7 nm to explore the effect of length scales on the plastic co-deformability of a metal and a ceramic. At 50 nm, plasticity was confined to the Al layers with easy initiation of cracks in the TiN layers. At 5 nm and below, cracking in TiN was suppressed and post mortem measurements indicated a reduction in layer thickness in both layers. Our results demonstrate the profound size effect in enhancing plastic co-deformability in nanoscale metal-ceramic multilayers.

  17. Corneal wound healing following laser in situ keratomileusis (LASIK): a histopathological study in rabbits

    PubMed Central

    Kato, T.; Nakayasu, K.; Hosoda, Y.; Watanabe, Y.; Kanai, A.

    1999-01-01

    AIMS—To investigate the histopathological changes of rabbit corneas after laser in situ keratomileusis (LASIK) and to evaluate the corneal wound healing process.
METHODS—A LASIK was performed on white rabbit eyes. Postoperatively, rabbits were killed on days 1 and 7, and at 1, 3, and 9 months.
RESULTS—Periodic acid Schiff (PAS) positive material and disorganised collagen fibre were seen along the interface of the corneal flap even 9 months after operation.
CONCLUSIONS—The wound healing process still continued at 9 months after LASIK indicating that a much longer time than expected was required for corneal wound healing following LASIK.

 PMID:10535863

  18. An in situ electron microscopy technique for the study of thermally activated reactions in multilayered materials

    SciTech Connect

    Wall, M.A.; Barbee, T.W. Jr.; Weihs, T.P.

    1995-04-14

    A novel in situ transmission electron microscopy technique for the observation of reaction processes in multilayered materials is reported. The technique involves constant heating rate experiments of multilayered materials in image and diffraction modes. Because the fine scale microstructure of multilayered materials is typically a small fraction of the TEM specimen thickness, realistic comparison of the microstructural evolution with that of similarly processed thick foil samples is possible. Such experiments, when well designed, can provide rapid characterization of phase transformations and stability of nano-structured materials. The results of these experiments can be recorded in both video and micrograph format. The results and limitations of this technique will be shown for the Al/Zr and Al/Monel multilayered systems.

  19. Study of tempering behavior of lath martensite using in situ neutron diffraction

    SciTech Connect

    Shi, Z.M.; Gong, W.; Tomota, Y.; Harjo, S.; Li, J.; Chi, B.; Pu, J.

    2015-09-15

    To elucidate changes in the density and substructure of dislocations during tempering of lath martensite steel, a convolutional multiple whole-profile fitting method was applied to in situ neutron diffraction profiles. With increasing tempering temperature, the dislocation density scarcely changed in the beginning and then decreased at temperatures above 473 K, whereas the dislocation arrangement drastically changed at temperatures above 673 K. The strength of the steel is speculated to depend on the density and arrangement of dislocations. - Highlights: • A convolutional multiple whole-profile fitting method was applied. • Dislocation density and dislocation arrangement changing with tempering were discussed. • Dislocation density scarcely changed in the beginning. • And then dislocation density decreased at temperatures above 473 K. • The dislocation arrangement drastically changed at temperatures above 673 K.

  20. In situ study of the initiation of hydrogen bubbles at the aluminium metal/oxide interface

    NASA Astrophysics Data System (ADS)

    Xie, De-Gang; Wang, Zhang-Jie; Sun, Jun; Li, Ju; Ma, Evan; Shan, Zhi-Wei

    2015-09-01

    The presence of excess hydrogen at the interface between a metal substrate and a protective oxide can cause blistering and spallation of the scale. However, it remains unclear how nanoscale bubbles manage to reach the critical size in the first place. Here, we perform in situ environmental transmission electron microscopy experiments of the aluminium metal/oxide interface under hydrogen exposure. It is found that once the interface is weakened by hydrogen segregation, surface diffusion of Al atoms initiates the formation of faceted cavities on the metal side, driven by Wulff reconstruction. The morphology and growth rate of these cavities are highly sensitive to the crystallographic orientation of the aluminium substrate. Once the cavities grow to a critical size, the internal gas pressure can become great enough to blister the oxide layer. Our findings have implications for understanding hydrogen damage of interfaces.

  1. Ecological correlates of ex situ seed longevity: a comparative study on 195 species

    PubMed Central

    Probert, Robin J.; Daws, Matthew I.; Hay, Fiona R.

    2009-01-01

    Background and Aims Extended seed longevity in the dry state is the basis for the ex situ conservation of ‘orthodox’ seeds. However, even under identical storage conditions there is wide variation in seed life-span between species. Here, the effects of seed traits and environmental conditions at the site of collection on seed longevity is explored for195 wild species from 71 families from environments ranging from cold deserts to tropical forests. Methods Seeds were rapidly aged at elevated temperature and relative humidity (either 45°C and 60% RH or 60°C and 60% RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50% (p50) was determined using Probit analysis and used as a measure of relative seed longevity between species. Key Results Across species, p50 at 45°C and 60% RH varied from 0·1 d to 771 d. Endospermic seeds were, in general, shorter lived than non-endospermic seeds and seeds from hot, dry environments were longer lived than those from cool, wet conditions. These relationships remained significant when controlling for the effects of phylogenetic relatedness using phylogenetically independent contrasts. Seed mass and oil content were not correlated with p50. Conclusions The data suggest that the endospermic seeds of early angiosperms which evolved in forest understorey habitats are short-lived. Extended longevity presumably evolved as a response to climatic change or the invasion of drier areas. The apparent short-lived nature of endospermic seeds from cool wet environments may have implications for re-collection and re-testing strategies in ex situ conservation. PMID:19359301

  2. In situ neutron scattering study of nanoscale phase evolution in PbTe-PbS thermoelectric material

    SciTech Connect

    Ren, Fei; Schmidt, Robert; Keum, Jong K.; Qian, Bosen; Case, Eldon D.; Littrell, Ken C.; An, Ke

    2016-08-24

    Introducing nanostructural second phases has been proved to be an effective approach to reduce the lattice thermal conductivity and thus enhance the figure of merit for many thermoelectric materials. Furthermore studies of the formation and evolution of these second phases are central to understanding temperature dependent material behavior, improving thermal stabilities, as well as designing new materials. We examined powder samples of PbTe-PbS thermoelectric material using in situ neutron diffraction and small angle neutron scattering (SANS) techniques from room temperature to elevated temperature up to 663 K, to explore quantitative information on the structure, weight fraction, and size of the second phase. Neutron diffraction data showed the as-milled powder was primarily solid solution before heat treatment. During heating, PbS second phase precipitated out of the PbTe matrix around 480 K, while re-dissolution started around 570 K. The second phase remained separated from the matrix upon cooling. Furthermore, SANS data indicated there are two populations of nanostructures. The size of the smaller nanostructure increased from initially 5 nm to approximately 25 nm after annealing at 650 K, while the size of the larger nanostructure remained unchanged. Our study demonstrated that in situ neutron techniques are effective means to obtain quantitative information to study temperature dependent nanostructural behavior of thermoelectrics and likely other high-temperature materials.

  3. In situ neutron scattering study of nanoscale phase evolution in PbTe-PbS thermoelectric material

    DOE PAGES

    Ren, Fei; Schmidt, Robert; Keum, Jong K.; ...

    2016-08-24

    Introducing nanostructural second phases has been proved to be an effective approach to reduce the lattice thermal conductivity and thus enhance the figure of merit for many thermoelectric materials. Furthermore studies of the formation and evolution of these second phases are central to understanding temperature dependent material behavior, improving thermal stabilities, as well as designing new materials. We examined powder samples of PbTe-PbS thermoelectric material using in situ neutron diffraction and small angle neutron scattering (SANS) techniques from room temperature to elevated temperature up to 663 K, to explore quantitative information on the structure, weight fraction, and size of themore » second phase. Neutron diffraction data showed the as-milled powder was primarily solid solution before heat treatment. During heating, PbS second phase precipitated out of the PbTe matrix around 480 K, while re-dissolution started around 570 K. The second phase remained separated from the matrix upon cooling. Furthermore, SANS data indicated there are two populations of nanostructures. The size of the smaller nanostructure increased from initially 5 nm to approximately 25 nm after annealing at 650 K, while the size of the larger nanostructure remained unchanged. Our study demonstrated that in situ neutron techniques are effective means to obtain quantitative information to study temperature dependent nanostructural behavior of thermoelectrics and likely other high-temperature materials.« less

  4. In situ neutron scattering study of nanoscale phase evolution in PbTe-PbS thermoelectric material

    NASA Astrophysics Data System (ADS)

    Ren, Fei; Schmidt, Robert; Keum, Jong K.; Qian, Bosen; Case, Eldon D.; Littrell, Ken C.; An, Ke

    2016-08-01

    Introducing nanostructural second phases has proved to be an effective approach to reduce the lattice thermal conductivity and thus enhances the figure of merit for many thermoelectric materials. Studies of the formation and evolution of these second phases are essential to understanding material temperature dependent behaviors, improving thermal stabilities, as well as designing new materials. In this study, powder samples of the PbTe-PbS thermoelectric material were examined using in situ neutron diffraction and small angle neutron scattering (SANS) techniques between room temperature and elevated temperature up to 663 K, to explore quantitative information on the structure, weight fraction, and size of the second phase. Neutron diffraction data showed that the as-milled powder was primarily a solid solution prior to heat treatment. During heating, a PbS second phase precipitated out of the PbTe matrix around 500 K, while re-dissolution started around 600 K. The second phase remained separated from the matrix upon cooling. Furthermore, SANS data indicated that there are two populations of nanostructures. The size of the smaller nanostructure increased from initially 5 nm to approximately 25 nm after annealing at 650 K, while the size of the larger one remained unchanged. This study demonstrated that in situ neutron techniques are effective means to obtain quantitative information on temperature-dependent nanostructural behavior of thermoelectrics and likely other high-temperature materials.

  5. Rotating Pip Detection and Stall Warning in High-Speed Compressors Using Structure Function

    NASA Technical Reports Server (NTRS)

    Bright, Michelle M.; Qammar, Helen; Vhora, Hanif; Schaffer, Michael

    1999-01-01

    A statistic for both rotating pip and incipient stall detection, called Structure Function is introduced for use in high speed research compressor environments. Experimental studies on stall inception processes have long observed two types of pre-stall compressor activity. Presently there exist methods for indicating modal stall precursive events in the compressor. This is a first application of a new method to detect rotating pip activity prior to stall in research compressors. The algorithm requires a very short sample of data to distinguish pip activity prior to stall, and thus may be used in a real time application. Additionally, this Structure Function algorithm is also used as a single sensor stall warning method under a variety of operating conditions, including clean inlet conditions, radially and circumferentially distorted inlet conditions, and in examples of steady air injection along the casing, and controlled air injection conditions. Structure Function provides a potential advantage over linear spectral techniques and wavelet algorithms for stall detection due to the simplicity of the algorithm and because it does not rely on a priori knowledge of frequency content.

  6. Concerted growth and ordering of cobalt nanorod arrays as revealed by tandem in situ SAXS-XAS studies

    SciTech Connect

    Cormary, Benoit; Li, Tao; Liakakos, Nikos; Peres, Laurent; Fazzini, Pier -Francesco; Blon, Thomas; Respaud, Marc; Kropf, A. Jeremy; Chaudret, Bruno; Miller, Jeffrey T.; Mader, Elizabeth A.; Soulantica, Katerina

    2016-06-14

    The molecular and ensemble dynamics for the growth of hierarchical supercrystals of cobalt nanorods have been studied by in situ tandem X-ray Absorption Spectroscopy – Small Angle X-ray Scattering (XAS - SAXS). The super-crystals were obtained by reducing a Co(II) precursor under H2 in the presence of a long chain amine and a long chain carboxylic acid. Complementary time-dependent ex situ TEM studies were also performed. The experimental data provide critical insights into the nanorod growth mechanism, and unequivocal evidence for a concerted growth-organization process. Nanorod formation involves cobalt nucleation, a fast atom by atom anisotropic growth and a slower oriented attach-ment process that continues well after cobalt reduction is complete. As a result, smectic-like ordering of the nanorods appears very early in the process, as soon as nanoparticle elongation appears, and nanorod growth takes place inside organized super-lattices, which can be regarded as mesocrystals.

  7. Column study of Cr(VI) removal by cationic hydrogel for in-situ remediation of contaminated groundwater and soil.

    PubMed

    Tang, Samuel C N; Yin, Ke; Lo, Irene M C

    2011-07-01

    Column experiments were conducted for examining the effectiveness of the cationic hydrogel on Cr(VI) removal from groundwater and soil. For in-situ groundwater remediation, the effects of background anions, humic acid (HA) and pH were studied. Cr(VI) has a higher preference for being adsorbed onto the cationic hydrogel than sulphate, bicarbonate ions and HA. However, the adsorbed HA reduced the Cr(VI) removal capacity of the cationic hydrogel, especially after regeneration of the adsorbents, probably due to the blockage of adsorption sites. The Cr(VI) removal was slightly influenced by the groundwater pH that could be attributed to Cr(VI) speciation. The 6-cycle regeneration and reusability study shows that the effectiveness of the cationic hydrogel remained almost unchanged. On average, 93% of the adsorbed Cr(VI) was recovered in each cycle and concentrated Cr(VI) solution was obtained after regeneration. For in-situ soil remediation, the flushing water pH had an insignificant effect on the release of Cr(VI) from the soils. Multiple-pulse flushing increased the removal of Cr(VI) from the soils. In contrast, more flushing water and longer operation may be required to achieve the same removal level by continuous flushing.

  8. In situ high pressure and temperature carbon-13 nmr for the study of carbonation reactions of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Surface, James Andrew

    The aqueous reactions of carbon dioxide with various Mg-containing minerals [MgO, Mg(OH)2, and Mg2SiO4] at several different pressures (1-200 bar) and temperatures (25-150C) have been studied using a novel, elevated pressure and temperature 13C NMR probe. Critical observations about reaction rates, chemical exchange, and pH measurements throughout these reactions and the implications of the in situ measurements made during these reactions are discussed. A new method is used to elucidate pH under high pressure and temperature conditions which utilizes a calculation scheme wherein experimental data and a computational model are combined. Additionally, a 1D pH imaging method is employed to observe pH gradient effects across mineral samples during their reaction with CO2. Finally, other experimental details are discussed including ex situ analysis on carbonate products using pXRD, Raman, and MAS NMR. Detailed discussion outlines how to use 13C NMR to study CO2 mineralization reactions.

  9. In-situ, real-time, studies of film growth processes using ion scattering and direct recoil spectroscopy techniques.

    SciTech Connect

    Smentkowski, V. S.

    1999-04-22

    Time-of-flight ion scattering and recoil spectroscopy (TOF-ISARS) enables the characterization of the composition and structure of surfaces with 1-2 monolayer specificity. It will be shown that surface analysis is possible at ambient pressures greater than 3 mTorr using TOF-ISARS techniques; allowing for real-time, in situ studies of film growth processes. TOF-ISARS comprises three analytical techniques: ion scattering spectroscopy (ISS), which detects the backscattered primary ion beam; direct recoil spectroscopy (DRS), which detects the surface species recoiled into the forward scattering direction; and mass spectroscopy of recoiled ions (MSRI), which is 3 variant of DRS capable of isotopic resolution for all surface species--including H and He. The advantages and limitations of each of these techniques will be discussed. The use of the three TOF-ISARS methods for real-time, in situ film growth studies at high ambient pressures will be illustrated. It will be shown that MSRI analysis is possible during sputter deposition. It will be also be demonstrated that the analyzer used for MSRI can also be used for time of flight secondary ion mass spectroscopy (TOF-SIMS) under high vacuum conditions. The use of a single analyzer to perform the complimentary surface analytical techniques of MSRI and SIMS is unique. The dwd functionality of the MSRI analyzer provides surface information not obtained when either MSRI or SIMS is used independently.

  10. Concerted growth and ordering of cobalt nanorod arrays as revealed by tandem in situ SAXS-XAS studies

    DOE PAGES

    Cormary, Benoit; Li, Tao; Liakakos, Nikos; ...

    2016-06-14

    The molecular and ensemble dynamics for the growth of hierarchical supercrystals of cobalt nanorods have been studied by in situ tandem X-ray Absorption Spectroscopy – Small Angle X-ray Scattering (XAS - SAXS). The super-crystals were obtained by reducing a Co(II) precursor under H2 in the presence of a long chain amine and a long chain carboxylic acid. Complementary time-dependent ex situ TEM studies were also performed. The experimental data provide critical insights into the nanorod growth mechanism, and unequivocal evidence for a concerted growth-organization process. Nanorod formation involves cobalt nucleation, a fast atom by atom anisotropic growth and a slowermore » oriented attach-ment process that continues well after cobalt reduction is complete. As a result, smectic-like ordering of the nanorods appears very early in the process, as soon as nanoparticle elongation appears, and nanorod growth takes place inside organized super-lattices, which can be regarded as mesocrystals.« less

  11. [In-situ DRIFTS study of coupling partial oxidation of methane and carbon dioxide reforming].

    PubMed

    Ji, Hong-bing; Xu, Jian-hua; Xie, Jun-feng; Chen, Qing-lin

    2008-06-01

    8%Ru-5%Ce/gamma-Al2O3 catalyst exhibited excellent catalytic performance for low temperature activation of methane. Although the conversion rates of methane were 25.3% for exothermal partial oxidation of methane, and 0.8% for endothermal carbon dioxide reforming, whose activity was rather low, 38.8% of conversion rate of methane could be obtained for the obtained coupling reaction at 500 degrees C owing to the coupling intensification between endothermal carbon dioxide reforming reaction and exothermal partial oxidation of methane. The mechanism of coupling partial oxidation of methane and carbon dioxide reforming on supported Ru catalyst was investigated by in-situ DRIFTS. The adsorption of CO on 8%Ru-5%Ce/gamma-Al2O3 showed that two kinds of doublet peaks which were characteristic adsorption of the gaseous CO at 2167 cm(-1) (2118 cm(-1)) to form Ru(CO)2 at 2031 cm(-1) (2034 cm(-1)) to form Ce(CO)2 were observed. These CO adsorption species wee easy to be desorbed from the surface of the catalyst at high temperature. The results of in-situ DRIFTS showed that carbonate, formal (formate) and carbon monoxide formed on the surface of catalyst, and formal (formate) was intermediate for the methane partial oxidation. This intermediate was formed through the combination of the adsorption species of methane CHx and the lattice oxygen adsorption species on the surface of catalyst, and syngas was produced through the splitting of this intermediate. The DRIFTS researching on carbon dioxide reforming showed that there was no new adsorption species on the surface of the catalyst, which indicated that the mechanism for carbon dioxide reforming was through the dissociation of the adsorbed methane and carbon dioxide. During the reaction of the coupling of carbon dioxide reforming reaction and partial oxidation of methane, there was hydroxyl adsorption species on the surface of catalyst. The mechanism of coupling methane, carbon dioxide and oxygen might be composed of the above

  12. Measuring spin-dependent structure functions at CEBAF

    SciTech Connect

    Schaefer, A.

    1994-04-01

    The author analyses whether CEBAF with a 10 GeV beam could contribute significantly to the understanding of spin-dependent deep-inelastic scattering as well as semi-inclusive reactions. The main advantage of CEBAF is the much better attainable statistics, its great disadvantage its comparably low energy, which limits the accessible x-range to about 0.15 to 0.7. Within these constraints CEBAF could provide (1) high precision data which would be very valuable to understand the Q{sup 2} dependence of the spin-dependent structure functions g{sub 1}(x) and G{sub 2}(x) and (2) the by far most precise determination of the third moments of g{sub 1}(x) and g{sub 2}(x) the latter of which the author argues to be related to a fundamental property of the nucleon.

  13. Pelvic fins in teleosts: structure, function and evolution.

    PubMed

    Yamanoue, Y; Setiamarga, D H E; Matsuura, K

    2010-10-01

    The pelvic fins of teleosts are paired appendages that are considered to be homologous to the hind limbs of tetrapods. Because they are less important for swimming, their morphology and function can be flexibly modified, and such modifications have probably facilitated the adaptations of teleosts to various environments. Recently, among these modifications, pelvic-fin loss has gained attention in evolutionary developmental biology. Pelvic-fin loss, however, has only been investigated in a few model species, and various biological aspects of pelvic fins in teleosts in general remain poorly understood. This review summarizes the current state of knowledge regarding pelvic fins, such as their structure, function and evolution, to elucidate their contribution to the considerable diversity of teleosts. This information could be invaluable for future investigations into various aspects of pelvic fins, which will provide clues to understanding the evolution, diversity and adaptations of teleosts.

  14. Structure-function analyses of plant type III polyketide synthases.

    PubMed

    Weng, Jing-Ke; Noel, Joseph P

    2012-01-01

    Plant type III polyketide synthases (PKSs) form a superfamily of biosynthetic enzymes involved in the production of a plethora of polyketide-derived natural products important for ecological adaptations and the fitness of land plants. Moreover, tremendous interest in bioengineering of type III PKSs to produce high-value compounds is increasing. Compared to type I and type II PKSs, which form either large modular protein complexes or dissociable molecular assemblies, type III PKSs exist as smaller homodimeric proteins, technically more amenable for detailed quantitative biochemical and phylogenetic analyses. In this chapter, we summarize a collection of approaches, including bioinformatics, genetics, protein crystallography, in vitro biochemistry, and mutagenesis, together affording a comprehensive interrogation of the structure-function-evolutionary relationships in the plant type III PKS family.

  15. Parton interpretation of the nucleon spin-dependent structure functions

    SciTech Connect

    Mankiewicz, L. ); Ryzak, Z. )

    1991-02-01

    We discuss the interpretation of the nucleon's polarized structure function {ital g}{sub 2}({ital x}). If the target state is represented by its Fock decomposition on the light cone, the operator-product expansion allows us to demonstrate that moments of {ital g}{sub 2}({ital x}) are related to overlap integrals between wave functions of opposite longitudinal polarizations. In the light-cone formalism such wave functions are related by the kinematical operator {ital scrY}, or light-cone parity. As a consequence, it can be shown that moments of {ital g}{sub 2} give information about the same parton wave function, or probability amplitude to find a certain parton configuration in the target which defines {ital g}{sub 1}({ital x}) or {ital F}{sub 2}({ital x}). Specific formulas are given, and possible applications to the phenomenology of the nucleon structure in QCD are discussed.

  16. Extraction of neutron structure from tagged structure functions

    NASA Astrophysics Data System (ADS)

    Cosyn, W.; Sargsian, M.

    2011-09-01

    We present work in a model used to describe semi-inclusive deep inelastic scattering off the deuteron. The model uses the virtual nucleon approximation to describe the interaction of the photon with the bound neutron and the generalized eikonal approximation is applied to calculate the final-state interaction diagram. Comparison with data taken at Jefferson Lab shows good agreement in the covered range of kinematics and points at a largely suppressed off-shell rescattering amplitude. The W and Q2 dependences of the total cross section and slope factor of the interaction of DIS products, X, off the spectator nucleon are extracted. Starting from the JLab data and our model calculations, we outline and apply an extrapolation method to obtain the neutron structure function F2N at high Bjorken x.

  17. Measuring Form Factors and Structure Functions with CLAS

    SciTech Connect

    G.P. Gilfoyle

    2007-09-10

    The physics program at the Thomas Jefferson National Accelerator Facility includes a strong effort to measure form factors and structure functions to probe the structure of hadronic matter, reveal the nature of confinement, and develop an understanding of atomic nuclei using quark-gluon degrees of freedom. The CLAS detector is a large acceptance device occupying one of the end stations. We discuss here two programs that use CLAS; measuring the magnetic form factor of the neutron and the virtual photon asymmetry of the proton. The form factor has been measured with unprecedented kinematic coverage and precision up to Q2=4.7 GeV2 and is consistent within 5%-10% of the dipole parameterization. The proton virtual photon asymmetry has been measured across a wide range in Bjorken x. The data exceed the SU(6)-symmetric quark prediction and show evidence of a smooth approach to the scaling limit prescribed by perturbative QCD.

  18. Breast Milk Oligosaccharides: Structure-Function Relationships in the Neonate

    PubMed Central

    Smilowitz, Jennifer T.; Lebrilla, Carlito B.; Mills, David A.; German, J. Bruce; Freeman, Samara L.

    2015-01-01

    In addition to providing complete postnatal nutrition, breast milk is a complex biofluid that delivers bioactive components for the growth and development of the intestinal and immune systems. Lactation is a unique opportunity to understand the role of diet in shaping the intestinal environment including the infant microbiome. Of considerable interest is the diversity and abundance of milk glycans that are energetically costly for the mammary gland to produce yet indigestible by infants. Milk glycans comprise free oligosaccharides, glycoproteins, glycopeptides, and glycolipids. Emerging technological advances are enabling more comprehensive, sensitive, and rapid analyses of these different classes of milk glycans. Understanding the impact of inter- and intraindividual glycan diversity on function is an important step toward interventions aimed at improving health and preventing disease. This review discusses the state of technology for glycan analysis and how specific structure-function knowledge is enhancing our understanding of early nutrition in the neonate. PMID:24850388

  19. Structure-function relationships in tendons: a review

    PubMed Central

    Benjamin, M; Kaiser, E; Milz, S

    2008-01-01

    The purpose of the current review is to highlight the structure-function relationship of tendons and related structures to provide an overview for readers whose interest in tendons needs to be underpinned by anatomy. Because of the availability of several recent reviews on tendon development and entheses, the focus of the current work is primarily directed towards what can best be described as the ‘tendon proper’ or the ‘mid-substance’ of tendons. The review covers all levels of tendon structure from the molecular to the gross and deals both with the extracellular matrix and with tendon cells. The latter are often called ‘tenocytes’ and are increasingly recognized as a defined cell population that is functionally and phenotypically distinct from other fibroblast-like cells. This is illustrated by their response to different types of mechanical stress. However, it is not only tendon cells, but tendons as a whole that exhibit distinct structure-function relationships geared to the changing mechanical stresses to which they are subject. This aspect of tendon biology is considered in some detail. Attention is briefly directed to the blood and nerve supply of tendons, for this is an important issue that relates to the intrinsic healing capacity of tendons. Structures closely related to tendons (joint capsules, tendon sheaths, pulleys, retinacula, fat pads and bursae) are also covered and the concept of a ‘supertendon’ is introduced to describe a collection of tendons in which the function of the whole complex exceeds that of its individual members. Finally, attention is drawn to the important relationship between tendons and fascia, highlighted by Wood Jones in his concept of an ‘ectoskeleton’ over half a century ago – work that is often forgotten today. PMID:18304204

  20. Helium effects on microstructural evolution in tempered martensitic steels: In situ helium implanter studies in HFIR

    SciTech Connect

    Yamamoto, Takuya; Odette, George R.; Miao, Pifeng; Edwards, Danny J.; Kurtz, Richard J.

    2009-04-30

    Microstructural evolutions in tempered martensitic steels (TMS) under neutron-irradiation, at fusion relevant He/dpa ratios and dpa rates, were characterized using a novel in situ He-implanter technique. F82H-mod3 was irradiated at 500 C in HFIR to a nominal 9 dpa and 190 or 380 appm He in both in the as-tempered (AT) and 20% cold-worked (CW) conditions. In all cases, a high number density of 1-2 nm He-bubbles were observed, along with fewer but larger 10 nm void-like faceted cavities. The He-bubbles form preferentially on dislocations and various interfaces. A slightly larger number of smaller He bubbles were observed in the CW condition. The lower He/dpa ratio produced slightly smaller and fewer He-bubbles. Comparisons of these observations to the results in nano-structured ferritic alloy (NFA) MA957 provide additional evidence that TMS may be susceptible to He-embrittlement as well as void swelling at fusion relevant He concentrations, while NFA are much more resistant to these degradation phenomena.

  1. In-situ infrared study of silicon in KOH electrolyte: Surface hydrogenation and hydrogen penetration

    NASA Astrophysics Data System (ADS)

    Philipsen, H. G. G.; Ozanam, F.; Allongue, P.; Kelly, J. J.; Chazalviel, J.-N.

    2016-02-01

    The n-Si(111)/6 M KOH electrolyte interface has been investigated by in-situ multiple-internal reflection infrared spectroscopy, at room temperature and at 40 °C. The potential of the Si electrode was stepped successively to positive and negative values with respect to open-circuit potential, leading to surface oxidation and oxide dissolution, respectively. Infrared spectra were recorded together with the interfacial current. Analysis of the infrared spectra indicates that, following the positive potential step, the electronic state of the surface changes from accumulation to inversion and the surface termination changes from a hydrogenated state to an oxidised state. The hydrogenated state is recovered after an induction time following the negative potential step. However, hydrogen penetration into the silicon lattice is then found to take place, as indicated by the appearance of a new SiH band and a strong background absorption of electronic origin. This sub-surface hydrogenation is associated with a slow increase of the interfacial current. This process is found to be especially important at higher temperature and is attributed to the formation of microcracks partially decorated with hydrogen. These results indicate that the chemistry and morphology of a silicon electrode are not stable even in the presence of an applied negative potential.

  2. In-Situ Study of Denitrification in the Elk Valley Aquifer, North Dakota

    NASA Astrophysics Data System (ADS)

    Korom, S. F.; Kammer, A. E.; Schlag, A. J.; Skubinna, P. A.

    2001-05-01

    Our hypothesis was that pyrite in the Elk Valley Aquifer (EVA) is a significant electron donor for denitrification. To test our hypothesis two large (1.5 m long by 0.4 m in diameter) stainless steel chambers were installed below the water table in the EVA. The isolated aquifer sediments formed in-situ mesocosms (ISMs). Groundwater was pumped from the "control" ISM, amended with bromide, and pumped back. Groundwater was pumped from the "nitrate" ISM, amended with bromide and nitrate such that the ionic strengths of the chemicals added to both ISMs were the same, and pumped back. After 272 days the nitrate decreased below detection and sulfate concentrations increased from 0.67 mmol/L to 2.37 mmol/L in the nitrate ISM. No increase in sulfate was observed in the control. During the experiment the delta 15N values in the remaining nitrate was concentrated from 2.4 per mil to 43.5 per mil. Using bromide to determine dilution rates in the nitrate chamber and assuming that denitrification explained any loss of nitrate above dilution, the denitrification rate was up to 0.015 mmol/L/day. As much as 61% of the denitrification could be explained by the oxidation of pyrite. The tracer test described above was repeated two times. Results indicated that denitrification rates decreased and the amount of denitrification attributable to pyrite oxidation also decreased.

  3. In-situ electron paramagnetic resonance studies of paramagnetic point defects in superconducting microwave resonators

    NASA Astrophysics Data System (ADS)

    Zhang, Shengke; Kopas, Cameron; Wagner, Brian; Queen, Daniel; Newman, N.

    2016-09-01

    The physical nature and concentration of paramagnetic point defects in the dielectrics of superconducting planar microwave resonators have been determined using in-situ electron paramagnetic resonance spectroscopy. To perform this work, the quality factor of parallel plate and stripline resonators was measured as a function of the magnitude of a magnetic-field applied parallel to the electrode surfaces. YBa2Cu3O7-δ thin film electrodes proved to be a preferred choice over Nb and MgB2 because they are readily available and have a small surface resistance (Rs) up to high temperatures (˜77 K) and magnetic fields (i.e., <1 T). Stripline resonators with a widely used high performance microwave dielectric, Co2+-doped Ba(Zn1/3Nb2/3)O3, are shown to have losses dominated by d-electron spin-excitations in exchange-coupled Co2+ point-defect clusters, even in the absence of an applied magnetic field. A significant enhanced microwave loss in stripline and parallel plate resonators is found to correlate with the presence of paramagnetic Mn2+ dopants in Ba(Zn1/3Ta2/3)O3 ceramics and dangling bond states in amorphous Si thin films, although the identification of the dominant loss mechanism(s) in these dielectrics requires further investigation.

  4. The electrochemical behaviour of copper in alkaline solutions containing fluoride, studied by in situ ellipsometry

    NASA Astrophysics Data System (ADS)

    Berlouis, L. E. A.; Mamman, D. A.; Azpuru, I. G.

    1998-06-01

    In situ ellipsometry has been used to reveal a number of interesting features in the growth of passivating films on Cu in 0.1 M KOH containing KF. Fluoride ions are shown to affect the growth of the oxide layer and enhanced dissolution of copper as the Cu II species occurs as a result of stress corrosion cracking. A restructuring of the oxide film within the passive region is attributed to loss of water and this effect becomes less distinct with increasing F - ion concentration in the electrolyte and disorder in the oxide layer. The enhanced reduction of the conductively inhibited bulk CuO/Cu(OH) 2 layer back to copper found in alkaline solutions containing fluoride would indicate that the formation of this layer is the dominant one for passivation of copper in this medium. The difference between the start and the end Δ- Ψ values of the metal surface of the cyclic voltammogram at -1.5 V versus SCE indicates either roughening arising from the oxide formation/reduction or the presence of a residual surface oxide.

  5. In situ SAXS study on size changes of platinum nanoparticles with temperature

    NASA Astrophysics Data System (ADS)

    Wang, W.; Chen, X.; Cai, Q.; Mo, G.; Jiang, L. S.; Zhang, K.; Chen, Z. J.; Wu, Z. H.; Pan, W.

    2008-09-01

    Poly(vinylpyrrolidone) (PVP)-coated platinum (Pt) nanoparticles were prepared in methanol-water reduction method. In situ small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) techniques were used to probe the size change of particles and crystallites with temperature. Tangent-by-tangent (TBT) method of SAXS data analysis was improved and used to get the particle size distribution (PSD) from SAXS intensity. Scherrer’s equation was used to derive the crystallite size from XRD pattern. Combining SAXS and XRD results, a step-like characteristic of the Pt nanoparticle growth has been found. Three stages (diffusion, aggregation, and agglomeration) can be used to describe the growth of the Pt nanoparticles and nanocrystallites. Aggregation was found to be the main growth mode of the Pt nanoparticles during heating. The maximum growth rates of Pt nanoparticles and Pt nanocrystallites, as well as the maximum aggregation degree of Pt nanocrystallites were found, respectively, at 250 °C, 350 °C and 300 °C. These results are helpful to understanding the growth mode of nanoparticles, as well as controlling the nanoparticle size.

  6. Effect of palygorskite clay on pyrolysis of rape straw: an in situ catalysis study.

    PubMed

    Liu, Haibo; Chen, Tianhu; Chang, Dongyin; Chen, Dong; Xie, Jingjing; Frost, Ray L

    2014-03-01

    Biomass tar restricts the wide application and development of biomass gasification technology. In the present paper, palygorskite, a natural magnesium-containing clay mineral, was investigated for catalytic pyrolysis of rape straw in situ and compared with the dolomite researched widely. The two types of natural minerals were characterized with XRD and BET. The results showed that combustible gas derived from the pyrolysis increased with an increase in gasification temperature. The H(conversion) and C(conversion) increased to 44.7% and 31% for the addition of palygorskite and increased to 41.3% and 31.3% for the addition of dolomite at the gasification temperature of 800°C, compared with 15.1% and 5.6% without addition of the two types of material. It indicated that more biomass was converted into combustible gases implying the decrease in biomass tar under the function of palygorskite or dolomite and palygorskite had a slightly better efficiency than that of dolomite in the experimental conditions.

  7. In Situ Detection of Subsurface Biofilm Using Low-Field NMR: A Field Study.

    PubMed

    Kirkland, Catherine M; Herrling, Maria P; Hiebert, Randy; Bender, Andrew T; Grunewald, Elliot; Walsh, David O; Codd, Sarah L

    2015-09-15

    Subsurface biofilms are central to bioremediation of chemical contaminants in soil and groundwater whereby micro-organisms degrade or sequester environmental pollutants like nitrate, hydrocarbons, chlorinated solvents and heavy metals. Current methods to monitor subsurface biofilm growth in situ are indirect. Previous laboratory research conducted at MSU has indicated that low-field nuclear magnetic resonance (NMR) is sensitive to biofilm growth in porous media, where biofilm contributes a polymer gel-like phase and enhances T2 relaxation. Here we show that a small diameter NMR well logging tool can detect biofilm accumulation in the subsurface using the change in T2 relaxation behavior over time. T2 relaxation distributions were measured over an 18 day experimental period by two NMR probes, operating at approximately 275 kHz and 400 kHz, installed in 10.2 cm wells in an engineered field testing site. The mean log T2 relaxation times were reduced by 62% and 43%, respectively, while biofilm was cultivated in the soil surrounding each well. Biofilm growth was confirmed by bleaching and flushing the wells and observing the NMR signal's return to baseline. This result provides a direct and noninvasive method to spatiotemporally monitor biofilm accumulation in the subsurface.

  8. In situ study of single-walled carbon nanotube growth in an environmental scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Mehedi, H.-A.; Ravaux, J.; Tahir, S.; Podor, R.; Jourdain, V.

    2016-12-01

    Monitoring individual single-walled carbon nanotubes (SWCNTs) during their growth is a highly sought-after goal in view of understanding the processes involved in the nucleation, elongation and termination which ultimately control the diameter and chiral selectivity. Here, we report on the first truly in situ observations of SWCNT growth in an environmental scanning electron microscope (ESEM). The CNT growth from lithographically patterned catalysts was investigated as a function of the catalyst type (Fe, Co or Ni), temperature, type of precursor (ethanol or acetylene), gas phase composition and pressure, and pretreatment conditions, and we report on the most appropriate conditions for SWCNT growth in ESEM conditions. We show that this approach allows the observation at the submicron scale of the different steps of the nanotube synthesis including the catalyst reduction, the growth and percolation of the nanotube network, and the deposition of individual nanotubes grown in the gas phase on the substrate. Despite these obvious advantages, we identified a few limitations which will need to be tackled for fully taking advantage of the approach, for instance for monitoring the growth of individual SWCNTs by ESEM, including the short lifetime of the catalyst nanoparticles, the preference for kite growth (by opposition to surface growth) and the influence of the electron beam on the nanotube growth.

  9. Chromosome orientation fluorescence in situ hybridization (CO-FISH) to study sister chromatid segregation in vivo

    PubMed Central

    Falconer, Ester; Chavez, Elizabeth; Henderson, Alexander; Lansdorp, Peter M.

    2013-01-01

    Previously, assays for sister chromatid segregation patterns relied on incorporation of BrdU and indirect methods to infer segregation patterns after two cell divisions. Here we describe a method to differentially label sister chromatids of murine cells and directly assay sister chromatid segregation patterns following one cell division in vitro and in vivo by adaptation of the well-established CO-FISH (chromosome orientation fluorescent in situ hybridization) technique. 5-bromo-2′-deoxyuridine (BrdU) is incorporated into newly-formed DNA strands, followed by photolysis and exonuclease digestion to create single-stranded sister chromatids containing parental template DNA only. Such single-stranded sister chromatids are differentially labeled using unidirectional probes to major satellite sequences coupled to fluorescent markers. Differentially-labeled sister chromatids in post-mitotic cells are visualized using fluorescence microscopy and sister chromatid segregation patterns can be directly assayed after one cell division. This procedure requires four days for in vivo mouse tissues, and two days for in vitro cultured cells. PMID:20595964

  10. In-situ NAP XPS studies of dissociative water adsorption on GaAs(100) surfaces

    NASA Astrophysics Data System (ADS)

    Ptasinska, Sylwia; Zhang, Xueqiang

    2014-03-01

    In current semiconductor-based technology it is important to design and fabricate new materials in order to achieve specific well-defined properties and functionalities. Before such systems can be applied they first need to be understood, refined and controlled. Therefore, a basic knowledge about molecule/semiconductor surface interfaces is essential. In the present work dissociative water adsorption on the GaAs(100) surface is monitored using X-ray Photoelectron Spectroscopy (XPS) performed in situ under near ambient conditions. Firstly, the crystal surface is exposed to water vapor pressures ranging from UHV to 0.5 kPa. At elevated pressures an increase of oxygenation and hydroxylation of Ga surface atoms has been observed in the Ga2p XPS spectra. Moreover, intense signals obtained from molecularly adsorbed water molecules or water molecules adsorbed via hydrogen bond to surface OH groups have been also observed in the O1s spectra. Finally, the crystal surface is annealed up to 700 K at water vapor pressure of 0.01 kPa, which leads to desorption of physisorbed water molecules and further increase of surface oxidation. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through grant number DE-FC02-04ER15533.

  11. IN SITU MAGIC ANGLE SPINNING NMR FOR STUDYING GEOLOGICAL CO(2) SEQUESTRATION

    SciTech Connect

    Hoyt, David W.; Turcu, Romulus VF; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Kwak, Ja Hun; Felmy, Andrew R.; Hu, Jian Z.

    2011-03-27

    Geological carbon sequestration (GCS) is one of the most promising ways of mitigating atmospheric greenhouse gases (1-3). Mineral carbonation reactions are potentially important to the long-term sealing effectiveness of caprock but remain poorly predictable, particularly in low-water supercritical CO2 (scCO2)-dominated environments where the chemistry has not been adequately explored. In situ probes that provide molecular-level information is desirable for investigating mechanisms and rates of GCS mineral carbonation reactions. MAS-NMR is a powerful tool for obtaining detailed molecular structure and dynamics information of a system regardless whether the system is in a solid, a liquid, a gaseous, or a supercritical state, or a mixture thereof (4,5). However, MAS NMR under scCO2 conditions has never been realized due to the tremendous technical difficulties of achieving and maintaining high pressure within a fast spinning MAS rotor (6,7), where non-metal materials must be used. In this work, we report development of a unique high pressure MAS NMR capability, and its application to mineral carbonation chemistry in scCO2 under geologically relevant temperatures and pressures.

  12. In situ infrared spectroscopic study of forsterite carbonation in wet supercritical CO2.

    PubMed

    Loring, John S; Thompson, Christopher J; Wang, Zheming; Joly, Alan G; Sklarew, Deborah S; Schaef, H Todd; Ilton, Eugene S; Rosso, Kevin M; Felmy, Andrew R

    2011-07-15

    Carbonation reactions are central to the prospect of CO(2) trapping by mineralization in geologic reservoirs. In contrast to the relevant aqueous-mediated reactions, little is known about the propensity for carbonation in the key partner fluid: supercritical carbon dioxide containing dissolved water ("wet" scCO(2)). We employed in situ mid-infrared spectroscopy to follow the reaction of a model silicate mineral (forsterite, Mg(2)SiO(4)) for 24 h with wet scCO(2) at 50 °C and 180 atm. The results show a dramatic dependence of reactivity on water concentration and the presence of liquid water on the forsterite particles. Exposure to neat scCO(2) showed no detectable carbonation reaction. At 47% and 81% water saturation, an Ångstrom-thick liquid-like water film was detected on the forsterite particles and less than 1% of the forsterite transformed. Most of the reaction occurred within the first 3 h of exposure to the fluid. In experiments at 95% saturation and with an excess of water (36% above water saturation), a nanometer-thick water film was detected, and the carbonation reaction proceeded continuously with approximately 2% and 10% conversion, respectively. Our collective results suggest constitutive links between water concentration, water film formation, reaction rate and extent, and reaction products in wet scCO(2).

  13. Arctic Gakkel Ridge hydrothermal plume study by in-situ redox and particle size measurements.

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Edmonds, H. N.; Winsor, P.; Liljebladh, B.; Stranne, C.; Upchurch, L.; Singh, H.; Jakuba, M.; Willis, C.; Shank, T.; Humphris, S. E.; Reves-Sohn, R.

    2007-12-01

    Throughout the Arctic Gakkel Vents Expediton (AGAVE cruise), Eh electrodes (redox sensor) were mounted on all vehicles, i.e., CTD/rosette, PUMA and JAGUAR AUVs and mini-ROV CAMPER. The electrodes voltages were logged through either SBE 9+ auxiliary channel (CTD) or RS-232C ports (PUMA and CAMPER) or self-recorded by an independent logger (JAGUAR). The LISST (Laser In-Situ Scattering and Transimssiometry)-Deep particle size analyzer was attached on the CTD/rosette with an independent data logger and a battery pack. Redox sensor has been used widely over different tectonic and oceanographic settings to detect hydrothermal emission. Negative shifts of redox voltage in the course of vehicle track lines as well as CTD casts provide an indication of "close range" from the source. None of CTD cast in the peridotite site (~85 deg N, 7.5 deg E) showed any redox negative shift. There were various magnitude of redox negative shift in different height from the bottom recorded in CTD casts and AUV and CAMPER track lines in the volcano site near the eastern end of bared central high (~85.5 deg N, 85 deg E). Although the redox negative shifts varied from almost a mV to almost a hundred mV, the redox data collected during the cruise could not confirm the existence of high temperature vents in the volcano site.

  14. In Situ Infrared Spectroscopic Study of Forsterite Carbonation in Wet Supercritical CO2

    SciTech Connect

    Loring, John S.; Thompson, Christopher J.; Wang, Zheming; Joly, Alan G.; Sklarew, Deborah S.; Schaef, Herbert T.; Ilton, Eugene S.; Rosso, Kevin M.; Felmy, Andrew R.

    2011-07-19

    Carbonation reactions are central to the prospect of CO2 trapping by mineralization in geologic reservoirs. In contrast to the relevant aqueous-mediated reactions, little is known about the propensity for carbonation in the long-term partner fluid: water-containing supercritical carbon dioxide (‘wet’ scCO2). We employed in situ mid-infrared spectroscopy to follow the reaction of a model silicate mineral (forsterite, Mg2SiO4) for 24 hr with wet scCO2 at 50°C and 180 atm, using water concentrations corresponding to 0%, 55%, 95%, and 136% saturation. Results show a dramatic dependence of reactivity on water concentration and the presence of liquid water on the forsterite particles. Exposure to neat scCO2 showed no detectable carbonation reaction. At 55% and 95% water saturation, a liquid-like thin water film was detected on the forsterite particles; less than 1% of the forsterite transformed, mostly within the first 3 hours of exposure to the fluid. At 136% saturation, where an (excess) liquid water film approximately several nanometers thick was intentionally condensed on the forsterite, the carbonation reaction proceeded continuously for 24 hr with 10% to 15% transformation. Our collective results suggest constitutive links between water concentration, water film formation, reaction rate and extent, and reaction products in wet scCO2.

  15. In situ ESEM study of the thermal decomposition of chrysotile asbestos in view of safe recycling of the transformation product.

    PubMed

    Gualtieri, Alessandro F; Gualtieri, Magdalena Lassinantti; Tonelli, Massimo

    2008-08-15

    The thermal transformation of asbestos into non-hazardous crystalline phases and their recycling is a promising solution for the "asbestos problem". The most common asbestos-containing industrial material produced worldwide is cement-asbestos. Knowledge of the kinetics of thermal transformation of asbestos fibers in cement-asbestos is of paramount importance for the optimization of the firing process at industrial scale. Here, environmental scanning electron microscopy (ESEM) was used for the first time to follow in situ the thermal transformation of chrysotile fibers present in cement-asbestos. It was found that the reaction kinetics of thermal transformation of chrysotile was highly slowed down in the presence of water vapor in the experimental chamber with respect to He. This was explained by chemisorbed water on the surface of the fibers which affected the dehydroxylation reaction and consequently the recrystallization into Mg-silicates. In the attempt to investigate alternative and faster firing routes for the decomposition of asbestos, a low melting glass was mixed with cement-asbestos and studied in situ to assess to which extent the decomposition of asbestos is favored. It was found that the addition of a low melting glass to cement-asbestos greatly improved the decomposition reaction and decreased the transformation temperatures.

  16. Investigation of three home-applied bleaching agents on enamel structure and mechanical properties: an in situ study

    NASA Astrophysics Data System (ADS)

    Sa, Yue; Wang, Zhejun; Ma, Xiao; Lei, Chang; Liang, Shanshan; Sun, Lili; Jiang, Tao; Wang, Yining

    2012-03-01

    The safety of at-home tooth bleaching, based upon carbamide peroxide (CP) or hydrogen peroxide (HP) as the active agent, has been questioned. The aim of the present study was to investigate the effects of three differently concentrated home-applied bleaching agents on human enamel under in situ conditions. Sixty specimens were divided randomly into four groups and treated with 10% CP, 15% CP, 20% CP, and distilled water, respectively. Raman spectroscopy, attenuated total reflectance-infrared (ATR-IR) spectroscopy, atomic force microscopy (AFM), microhardness, and fracture toughness (FT) measurements were conducted to determine variations on enamel structure and mechanical properties before and after the bleaching process. Raman revealed little variation of Raman relative intensity after treatment with CP, which was consistent with the results of ATR-IR, AFM, and microhardness analyses. In addition, laser-induced fluorescence (LIF) intensity, and FT showed significant decreases on CP-treated specimens. These findings suggested there were minimal demineralization effects of the three at-home bleaching agents on enamel in situ. However, the decrease of LIF intensity and FT on enamel seemed to be inevitable.

  17. PACAP is transiently expressed in anterior pituitary gland of rats: in situ hybridization and cell immunoblot assay studies.

    PubMed

    Heinzlmann, Andrea; Kirilly, Eszter; Meltzer, Kinga; Szabó, Eniko; Baba, Akemichi; Hashimoto, Hitoshi; Köves, Katalin

    2008-04-01

    In this work the expression of PACAP (pituitary adenylate cyclase activating polypeptide) in rat anterior pituitary was demonstrated for the first time using in situ hybridization. The number of cells showing PACAP signal in intact male rats was negligible similarly to that of diestrous rats. In proestrous rats sacrificed at 10h there was a moderate increase in the expression and after a decrease at 16 h and 18 h, there was a transient peak at 20 h and then the number of labeled cells was declined again (22 h). In the cell immunoblot assay study it was observed that the number of PACAP blot forming (PACAP releasing) cells in an anterior pituitary cell culture changed according to a similar pattern as the number of PACAP expressing cells. The number of blots was also the highest when the animals were sacrificed in the evening of proestrus at 20h. The results obtained by in situ hybridization and cell immunoblot assay well correlate with each other. The above-mentioned results support our hypothesis that the enhanced expression and secretion of PACAP in the pituitary gland may be involved in ceasing the LH surge.

  18. Nitric oxide synthase expression in the central nervous system of Sepia officinalis: an in situ hybridization study.

    PubMed

    Di Cristo, Carlo; Fiore, Gabriella; Scheinker, Vladimir; Enikolopov, Grigori; d'Ischia, Marco; Palumbo, Anna; Di Cosmo, Anna

    2007-09-01

    We recently reported the molecular cloning of nitric oxide synthase (NOS) mRNA from Sepia officinalis (SoNOS) using a strategy that involves hybridization of degenerate PCR primers to highly conserved NOS regions, combined with a RACE procedure. Here, in situ hybridization study has been performed on serial sections of the cuttlefish central nervous system to reveal localized specific staining of cell bodies in several lobes of the brain. Staining was found in many lower motor centres, including cells of the inferior and superior buccal lobes (feeding centres); in some higher motor centres (anterior basal and peduncle lobes); in learning centres (vertical, subvertical and superior frontal lobes); and in the visual system [medulla and deep retina (optic lobe)]. Positive staining was also found in the olfactory lobe. NOS-expressing cells have been detected also in the interbasal lobe. Double labelling experiments, performed on consecutive sections, showed that neurons containing NOS immunoreactivity were also positive in in situ hybridization staining. All these data support the presence of NOS in several systems in the cuttlefish brain.

  19. Enamel demineralization with two forms of archwire ligation investigated using an in situ caries model--a pilot study.

    PubMed

    Gameiro, Gustavo Hauber; Nouer, Darcy Flávio; Cenci, Maximiliano Sérgio; Cury, Jaime Aparecido

    2009-10-01

    A modified in situ model to assess enamel demineralization around orthodontic devices was developed and a pilot study was conducted to evaluate two types of archwire ligation. Enamel blocks were placed in palatal removable appliances where orthodontic brackets were bonded. The brackets on one side of the appliance were ligated with elastomeric rings and those on the other side with stainless steel wires. Four volunteers (two males, two females), mean age 27 years, wore the appliances for 14 days during which time a 20 per cent sucrose solution was dripped eight times a day onto the enamel blocks. The biofilm formed around the brackets was collected for microbiological analyses and the mineral loss around the brackets was determined by cross-sectional microhardness measurement. The ligatures evaluated did not differ significantly from each other regarding biofilm weight, total bacteria, total streptococci, mutans streptococci, or lactobacilli counts (P > 0.05, Wilcoxon paired test). Enamel demineralization was also not different around the brackets for the different ligation methods (P > 0.05, split-split-plot analysis of variance). However, a statistical power analysis based on the data showed a trend to higher demineralization around brackets ligated with elastomeric rings. The developed modified in situ model may be suitable to assess the caries potential of clinical procedures used in orthodontic treatment.

  20. In situ characterization of protein aggregates in human tissues affected by light chain amyloidosis: a FTIR microspectroscopy study

    PubMed Central

    Ami, Diletta; Lavatelli, Francesca; Rognoni, Paola; Palladini, Giovanni; Raimondi, Sara; Giorgetti, Sofia; Monti, Luca; Doglia, Silvia Maria; Natalello, Antonino; Merlini, Giampaolo

    2016-01-01

    Light chain (AL) amyloidosis, caused by deposition of amyloidogenic immunoglobulin light chains (LCs), is the most common systemic form in industrialized countries. Still open questions, and premises for developing targeted therapies, concern the mechanisms of amyloid formation in vivo and the bases of organ targeting and dysfunction. Investigating amyloid material in its natural environment is crucial to obtain new insights on the molecular features of fibrillar deposits at individual level. To this aim, we used Fourier transform infrared (FTIR) microspectroscopy for studying in situ unfixed tissues (heart and subcutaneous abdominal fat) from patients affected by AL amyloidosis. We compared the infrared response of affected tissues with that of ex vivo and in vitro fibrils obtained from the pathogenic LC derived from one patient, as well as with that of non amyloid-affected tissues. We demonstrated that the IR marker band of intermolecular β-sheets, typical of protein aggregates, can be detected in situ in LC amyloid-affected tissues, and that FTIR microspectroscopy allows exploring the inter- and intra-sample heterogeneity. We extended the infrared analysis to the characterization of other biomolecules embedded within the amyloid deposits, finding an IR pattern that discloses a possible role of lipids, collagen and glycosaminoglycans in amyloid deposition in vivo. PMID:27373200