Temporal resolution of PrPSc transport, PrPSc accumulation, activation of glia and neuronal death in retinas from C57Bl/6 mice inoculated with RML scrapie: Relevance to biomarkers of prion disease progression

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Currently, there is a lack of pathologic landmarks to objectively evaluate the progression of prion disease in vivo. The goal of this work was to determine the temporal relationship between transport of misfolded prion protein to the retina from the brain, accumulation of PrPSc in the retina, the re...

Co-existence of Distinct Prion Types Enables Conformational Evolution of Human PrPSc by Competitive Selection

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Haldiman, T.; Kim, C.; Cohen, Y.; Chen, W.; Blevins, J.; Qing, L.; Cohen, M.L.; Langeveld, J.P.M.; Telling, G.C.; Kong, Q.; Safar, J.G.

2013-01-01

The unique phenotypic characteristics of mammalian prions are thought to be encoded in the conformation of pathogenic prion proteins (PrPSc). The molecular mechanism responsible for the adaptation, mutation, and evolution of prions observed in cloned cells and upon crossing the species barrier

Detection of PrP(Sc) in peripheral tissues of clinically affected cattle after oral challenge with bovine spongiform encephalopathy

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Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative prion disease that affects cattle and can be transmitted to human beings as new variant Creutzfeldt-Jakob disease (vCJD). A protease-resistant, disease-associated isoform of the prion protein (PrP**Sc) accumulates in the central ner...

Prion seeding activities of mouse scrapie strains with divergent PrPSc protease sensitivities and amyloid plaque content using RT-QuIC and eQuIC.

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Sarah Vascellari

Full Text Available Different transmissible spongiform encephalopathy (TSE-associated forms of prion protein (e.g. PrP(Sc can vary markedly in ultrastructure and biochemical characteristics, but each is propagated in the host. PrP(Sc propagation involves conversion from its normal isoform, PrP(C, by a seeded or templated polymerization mechanism. Such a mechanism is also the basis of the RT-QuIC and eQuIC prion assays which use recombinant PrP (rPrP(Sen as a substrate. These ultrasensitive detection assays have been developed for TSE prions of several host species and sample tissues, but not for murine models which are central to TSE pathogenesis research. Here we have adapted RT-QuIC and eQuIC to various murine prions and evaluated how seeding activity depends on glycophosphatidylinositol (GPI anchoring and the abundance of amyloid plaques and protease-resistant PrP(Sc (PrP(Res. Scrapie brain dilutions up to 10(-8 and 10(-13 were detected by RT-QuIC and eQuIC, respectively. Comparisons of scrapie-affected wild-type mice and transgenic mice expressing GPI anchorless PrP showed that, although similar concentrations of seeding activity accumulated in brain, the heavily amyloid-laden anchorless mouse tissue seeded more rapid reactions. Next we compared seeding activities in the brains of mice with similar infectivity titers, but widely divergent PrP(Res levels. For this purpose we compared the 263K and 139A scrapie strains in transgenic mice expressing P101L PrP(C. Although the brains of 263K-affected mice had little immunoblot-detectable PrP(Res, RT-QuIC indicated that seeding activity was comparable to that associated with a high-PrP(Res strain, 139A. Thus, in this comparison, RT-QuIC seeding activity correlated more closely with infectivity than with PrP(Res levels. We also found that eQuIC, which incorporates a PrP(Sc immunoprecipitation step, detected seeding activity in plasma from wild-type and anchorless PrP transgenic mice inoculated with 22L, 79A and/or RML

Subcritical Water Hydrolysis Effectively Reduces the In Vitro Seeding Activity of PrPSc but Fails to Inactivate the Infectivity of Bovine Spongiform Encephalopathy Prions.

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Yuichi Murayama

Full Text Available The global outbreak of bovine spongiform encephalopathy (BSE has been attributed to the recycling of contaminated meat and bone meals (MBMs as feed supplements. The use of MBMs has been prohibited in many countries; however, the development of a method for inactivating BSE prions could enable the efficient and safe use of these products as an organic resource. Subcritical water (SCW, which is water heated under pressure to maintain a liquid state at temperatures below the critical temperature (374°C, exhibits strong hydrolytic activity against organic compounds. In this study, we examined the residual in vitro seeding activity of protease-resistant prion protein (PrPSc and the infectivity of BSE prions after SCW treatments. Spinal cord homogenates prepared from BSE-infected cows were treated with SCW at 230-280°C for 5-7.5 min and used to intracerebrally inoculate transgenic mice overexpressing bovine prion protein. Serial protein misfolding cyclic amplification (sPMCA analysis detected no PrPSc in the SCW-treated homogenates, and the mice treated with these samples survived for more than 700 days without any signs of disease. However, sPMCA analyses detected PrPSc accumulation in the brains of all inoculated mice. Furthermore, secondary passage mice, which inoculated with brain homogenates derived from a western blotting (WB-positive primary passage mouse, died after an average of 240 days, similar to mice inoculated with untreated BSE-infected spinal cord homogenates. The PrPSc accumulation and vacuolation typically observed in the brains of BSE-infected mice were confirmed in these secondary passage mice, suggesting that the BSE prions maintained their infectivity after SCW treatment. One late-onset case, as well as asymptomatic but sPMCA-positive cases, were also recognized in secondary passage mice inoculated with brain homogenates from WB-negative but sPMCA-positive primary passage mice. These results indicated that SCW

Prion structure investigated in situ, ex vivo, and in vitro by FTIR spectroscopy

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Kneipp, Janina; Miller, Lisa M.; Spassov, Sashko; Sokolowski, Fabian; Lasch, Peter; Beekes, Michael; Naumann, Dieter

2004-07-01

Syrian hamster nervous tissue was investigated by FTIR microspectroscopy with conventional and synchrotron infrared light sources. Various tissue structures from the cerebellum and medulla oblongata of scrapie-infected and control hamsters were investigated at a spatial resolution of 50 μm. Single neurons in dorsal root ganglia of scrapie-infected hamsters were analyzed by raster scan mapping at 6 μm spatial resolution. These measurements enabled us to (i) scrutinize structural differences between infected and non-infected tissue and (ii) analyze for the first time the distribution of different protein structures in situ within single nerve cells. Single nerve cells exhibited areas of increased β-sheet content, which co-localized consistently with accumulations of the pathological prion protein (PrPSc). Spectral data were also obtained from purified, partly proteinase K digested PrPSc isolated from scrapie-infected nervous tissue of hamsters to elucidate similarities/dissimilarities between prion structure in situ and ex vivo. A further comparison is drawn to the recombinant Syrian hamster prion protein SHaPrP90-232, whose in vitro transition from the predominantly a-helical isoform to β-sheet rich oligomeric structures was also investigated by FTIR spectroscopy.

Incidence and spectrum of sporadic Creutzfeldt-Jakob disease variants with mixed phenotype and co-occurrence of PrPSc types: an updated classification

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Parchi, P.; Strammiello, R.; Notari, S.; Giese, A.; Langeveld, J.P.M.; Ladogana, A.; Zerr, I.; Roncaroli, F.; Cras, P.; Ghetti, B.; Pocchiari, M.; Kretzschmar, H.; Capellari, S.

2009-01-01

Six subtypes of sporadic Creutzfeldt-Jakob disease with distinctive clinico-pathological features have been identified largely based on two types of the abnormal prion protein, PrPSc, and the methionine (M)/valine (V) polymorphic codon 129 of the prion protein. The existence of affected subjects

The Structural Architecture of an Infectious Mammalian Prion Using Electron Cryomicroscopy.

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Ester Vázquez-Fernández

2016-09-01

Full Text Available The structure of the infectious prion protein (PrPSc, which is responsible for Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy, has escaped all attempts at elucidation due to its insolubility and propensity to aggregate. PrPSc replicates by converting the non-infectious, cellular prion protein (PrPC into the misfolded, infectious conformer through an unknown mechanism. PrPSc and its N-terminally truncated variant, PrP 27-30, aggregate into amorphous aggregates, 2D crystals, and amyloid fibrils. The structure of these infectious conformers is essential to understanding prion replication and the development of structure-based therapeutic interventions. Here we used the repetitive organization inherent to GPI-anchorless PrP 27-30 amyloid fibrils to analyze their structure via electron cryomicroscopy. Fourier-transform analyses of averaged fibril segments indicate a repeating unit of 19.1 Å. 3D reconstructions of these fibrils revealed two distinct protofilaments, and, together with a molecular volume of 18,990 Å3, predicted the height of each PrP 27-30 molecule as ~17.7 Å. Together, the data indicate a four-rung β-solenoid structure as a key feature for the architecture of infectious mammalian prions. Furthermore, they allow to formulate a molecular mechanism for the replication of prions. Knowledge of the prion structure will provide important insights into the self-propagation mechanisms of protein misfolding.

Using small molecule reagents to help distinguish among prion structural models

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The only demonstrated difference between infectious prions (PrPSc) and the isosequential normal cellular prion protein (PrPC) is conformation. The structure of PrPC has been determined by a variety of instrumental techniques. The structure of prions remains uncertain. Recent instrumental analysis h...

Using mass spectrometry and small molecule reagents to detect distinctive structural features of different prion conformations (strains)

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A prion (PrPSc) is a conformer of a normal cellular prion protein (PrPC). Although they are isosequential, PrPSc is an infectious protein able to convert PrPC into the prion conformation and thereby propagate an infection. PrPC is monomeric while PrPSc is a multimer. PrPSc can adopt more than one co...

Glycoform-independent prion conversion by highly efficient, cell-based, protein misfolding cyclic amplification.

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Moudjou, Mohammed; Chapuis, Jérôme; Mekrouti, Mériem; Reine, Fabienne; Herzog, Laetitia; Sibille, Pierre; Laude, Hubert; Vilette, Didier; Andréoletti, Olivier; Rezaei, Human; Dron, Michel; Béringue, Vincent

2016-07-07

Prions are formed of misfolded assemblies (PrP(Sc)) of the variably N-glycosylated cellular prion protein (PrP(C)). In infected species, prions replicate by seeding the conversion and polymerization of host PrP(C). Distinct prion strains can be recognized, exhibiting defined PrP(Sc) biochemical properties such as the glycotype and specific biological traits. While strain information is encoded within the conformation of PrP(Sc) assemblies, the storage of the structural information and the molecular requirements for self-perpetuation remain uncertain. Here, we investigated the specific role of PrP(C) glycosylation status. First, we developed an efficient protein misfolding cyclic amplification method using cells expressing the PrP(C) species of interest as substrate. Applying the technique to PrP(C) glycosylation mutants expressing cells revealed that neither PrP(C) nor PrP(Sc) glycoform stoichiometry was instrumental to PrP(Sc) formation and strainness perpetuation. Our study supports the view that strain properties, including PrP(Sc) glycotype are enciphered within PrP(Sc) structural backbone, not in the attached glycans.

Polo-like kinase 3 (PLK3) mediates the clearance of the accumulated PrP mutants transiently expressed in cultured cells and pathogenic PrP(Sc) in prion infected cell line via protein interaction.

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Wang, Hui; Tian, Chan; Fan, Xue-Yu; Chen, Li-Na; Lv, Yan; Sun, Jing; Zhao, Yang-Jing; Zhang, Lu-bin; Wang, Jing; Shi, Qi; Gao, Chen; Chen, Cao; Shao, Qi-Xiang; Dong, Xiao-Ping

2015-05-01

Polo-like kinases (PLKs) family has long been known to be critical for cell cycle and recent studies have pointed to new dimensions of PLKs function in the nervous system. Our previous study has verified that the levels of PLK3 in the brain are severely downregulated in prion-related diseases. However, the associations of PLKs with prion protein remain unclear. In the present study, we confirmed that PrP protein constitutively interacts with PLK3 as determined by both in vitro and in vivo assays. Both the kinase domain and polo-box domain of PLK3 were proved to bind PrP proteins expressed in mammalian cell lines. Overexpression of PLK3 did not affect the level of wild-type PrP, but significantly decreased the levels of the mutated PrPs in cultured cells. The kinase domain appeared to be responsible for the clearance of abnormally aggregated PrPs, but this function seemed to be independent of its kinase activity. RNA-mediated knockdown of PLK3 obviously aggravated the accumulation of cytosolic PrPs. Moreover, PLK3 overexpression in a scrapie infected cell line caused notable reduce of PrP(Sc) level in a dose-dependent manner, but had minimal effect on the expression of PrP(C) in its normal partner cell line. Our findings here confirmed the molecular interaction between PLK3 and PrP and outlined the regulatory activity of PLK3 on the degradation of abnormal PrPs, even its pathogenic isoform PrP(Sc). We, therefore, assume that the recovery of PLK3 in the early stage of prion infection may be helpful to prevent the toxic accumulation of PrP(Sc) in the brain tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structural determinants of phenotypic diversity and replication rate of human prions.

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Jiri G Safar

2015-04-01

Full Text Available The infectious pathogen responsible for prion diseases is the misfolded, aggregated form of the prion protein, PrPSc. In contrast to recent progress in studies of laboratory rodent-adapted prions, current understanding of the molecular basis of human prion diseases and, especially, their vast phenotypic diversity is very limited. Here, we have purified proteinase resistant PrPSc aggregates from two major phenotypes of sporadic Creutzfeldt-Jakob disease (sCJD, determined their conformational stability and replication tempo in vitro, as well as characterized structural organization using recently emerged approaches based on hydrogen/deuterium (H/D exchange coupled with mass spectrometry. Our data clearly demonstrate that these phenotypically distant prions differ in a major way with regard to their structural organization, both at the level of the polypeptide backbone (as indicated by backbone amide H/D exchange data as well as the quaternary packing arrangements (as indicated by H/D exchange kinetics for histidine side chains. Furthermore, these data indicate that, in contrast to previous observations on yeast and some murine prion strains, the replication rate of sCJD prions is primarily determined not by conformational stability but by specific structural features that control the growth rate of prion protein aggregates.

Prion protein gene variability in Spanish goats. Inference through susceptibility to classical scrapie strains and pathogenic distribution of peripheral PrP(sc..

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Cristina Acín

Full Text Available Classical scrapie is a neurological disorder of the central nervous system (CNS characterized by the accumulation of an abnormal, partially protease resistant prion protein (PrP(sc in the CNS and in some peripheral tissues in domestic small ruminants. Whereas the pathological changes and genetic susceptibility of ovine scrapie are well known, caprine scrapie has been less well studied. We report here a pathological study of 13 scrapie-affected goats diagnosed in Spain during the last 9 years. We used immunohistochemical and biochemical techniques to discriminate between classical and atypical scrapie and bovine spongiform encephalopathy (BSE. All the animals displayed PrP(sc distribution patterns and western blot characteristics compatible with classical scrapie. In addition, we determined the complete open reading frame sequence of the PRNP in these scrapie-affected animals. The polymorphisms observed were compared with those of the herd mates (n = 665 and with the frequencies of healthy herds (n = 581 of native Spanish goats (Retinta, Pirenaica and Moncaina and other worldwide breeds reared in Spain (Saanen, Alpine and crossbreed. In total, sixteen polymorphic sites were identified, including the known amino acid substitutions at codons G37V, G127S, M137I, I142M, H143R, R151H, R154H, R211Q, Q222K, G232W, and P240S, and new polymorphisms at codons G74D, M112T, R139S, L141F and Q215R. In addition, the known 42, 138 and 179 silent mutations were detected, and one new one is reported at codon 122. The genetic differences observed in the population studied have been attributed to breed and most of the novel polymorphic codons show frequencies lower than 5%. This work provides the first basis of polymorphic distribution of PRNP in native and worldwide goat breeds reared in Spain.

Prions in the Urine of Patients with Variant Creutzfeldt–Jakob Disease

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Moda, Fabio; Gambetti, Pierluigi; Notari, Silvio; Concha-Marambio, Luis; Catania, Marcella; Park, Kyung-Won; Maderna, Emanuela; Suardi, Silvia; Haïk, Stéphane; Brandel, Jean-Philippe; Ironside, James; Knight, Richard; Tagliavini, Fabrizio; Soto, Claudio

2014-01-01

BACKGROUND Prions, the infectious agents responsible for transmissible spongiform encephalopathies, consist mainly of the misfolded prion protein (PrPSc). The unique mechanism of transmission and the appearance of a variant form of Creutzfeldt–Jakob disease, which has been linked to consumption of prion-contaminated cattle meat, have raised concerns about public health. Evidence suggests that variant Creutzfeldt–Jakob disease prions circulate in body fluids from people in whom the disease is silently incubating. METHODS To investigate whether PrPSc can be detected in the urine of patients with variant Creutzfeldt–Jakob disease, we used the protein misfolding cyclic amplification (PMCA) technique to amplify minute quantities of PrPSc, enabling highly sensitive detection of the protein. We analyzed urine samples from several patients with various transmissible spongiform encephalopathies (variant and sporadic Creutzfeldt–Jakob disease and genetic forms of prion disease), patients with other degenerative or nondegenerative neurologic disorders, and healthy persons. RESULTS PrPSc was detectable only in the urine of patients with variant Creutzfeldt–Jakob disease and had the typical electrophoretic profile associated with this disease. PrPSc was detected in 13 of 14 urine samples obtained from patients with variant Creutzfeldt–Jakob disease and in none of the 224 urine samples obtained from patients with other neurologic diseases and from healthy controls, resulting in an estimated sensitivity of 92.9% (95% confidence interval [CI], 66.1 to 99.8) and a specificity of 100.0% (95% CI, 98.4 to 100.0). The PrPSc concentration in urine calculated by means of quantitative PMCA was estimated at 1×10−16 g per milliliter, or 3×10−21 mol per milliliter, which extrapolates to approximately 40 to 100 oligomeric particles of PrPSc per milliliter of urine. CONCLUSIONS Urine samples obtained from patients with variant Creutzfeldt–Jakob disease contained minute

Prions in the urine of patients with variant Creutzfeldt-Jakob disease.

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Moda, Fabio; Gambetti, Pierluigi; Notari, Silvio; Concha-Marambio, Luis; Catania, Marcella; Park, Kyung-Won; Maderna, Emanuela; Suardi, Silvia; Haïk, Stéphane; Brandel, Jean-Philippe; Ironside, James; Knight, Richard; Tagliavini, Fabrizio; Soto, Claudio

2014-08-07

Prions, the infectious agents responsible for transmissible spongiform encephalopathies, consist mainly of the misfolded prion protein (PrP(Sc)). The unique mechanism of transmission and the appearance of a variant form of Creutzfeldt-Jakob disease, which has been linked to consumption of prion-contaminated cattle meat, have raised concerns about public health. Evidence suggests that variant Creutzfeldt-Jakob disease prions circulate in body fluids from people in whom the disease is silently incubating. To investigate whether PrP(Sc) can be detected in the urine of patients with variant Creutzfeldt-Jakob disease, we used the protein misfolding cyclic amplification (PMCA) technique to amplify minute quantities of PrP(Sc), enabling highly sensitive detection of the protein. We analyzed urine samples from several patients with various transmissible spongiform encephalopathies (variant and sporadic Creutzfeldt-Jakob disease and genetic forms of prion disease), patients with other degenerative or nondegenerative neurologic disorders, and healthy persons. PrP(Sc) was detectable only in the urine of patients with variant Creutzfeldt-Jakob disease and had the typical electrophoretic profile associated with this disease. PrP(Sc) was detected in 13 of 14 urine samples obtained from patients with variant Creutzfeldt-Jakob disease and in none of the 224 urine samples obtained from patients with other neurologic diseases and from healthy controls, resulting in an estimated sensitivity of 92.9% (95% confidence interval [CI], 66.1 to 99.8) and a specificity of 100.0% (95% CI, 98.4 to 100.0). The PrP(Sc) concentration in urine calculated by means of quantitative PMCA was estimated at 1×10(-16) g per milliliter, or 3×10(-21) mol per milliliter, which extrapolates to approximately 40 to 100 oligomeric particles of PrP(Sc) per milliliter of urine. Urine samples obtained from patients with variant Creutzfeldt-Jakob disease contained minute quantities of PrP(Sc). (Funded by the

Prion disease susceptibility is affected by β-structure folding propensity and local side-chain interactions in PrP

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Khan, M. Qasim; Sweeting, Braden; Mulligan, Vikram Khipple; Arslan, Pharhad Eli; Cashman, Neil R.; Pai, Emil F.; Chakrabartty, Avijit

2010-01-01

Prion diseases occur when the normally α-helical prion protein (PrP) converts to a pathological β-structured state with prion infectivity (PrPSc). Exposure to PrPSc from other mammals can catalyze this conversion. Evidence from experimental and accidental transmission of prions suggests that mammals vary in their prion disease susceptibility: Hamsters and mice show relatively high susceptibility, whereas rabbits, horses, and dogs show low susceptibility. Using a novel approach to quantify conformational states of PrP by circular dichroism (CD), we find that prion susceptibility tracks with the intrinsic propensity of mammalian PrP to convert from the native, α-helical state to a cytotoxic β-structured state, which exists in a monomer–octamer equilibrium. It has been controversial whether β-structured monomers exist at acidic pH; sedimentation equilibrium and dual-wavelength CD evidence is presented for an equilibrium between a β-structured monomer and octamer in some acidic pH conditions. Our X-ray crystallographic structure of rabbit PrP has identified a key helix-capping motif implicated in the low prion disease susceptibility of rabbits. Removal of this capping motif increases the β-structure folding propensity of rabbit PrP to match that of PrP from mouse, a species more susceptible to prion disease. PMID:21041683

Prion disease susceptibility is affected by beta-structure folding propensity and local side-chain interactions in PrP.

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Khan, M Qasim; Sweeting, Braden; Mulligan, Vikram Khipple; Arslan, Pharhad Eli; Cashman, Neil R; Pai, Emil F; Chakrabartty, Avijit

2010-11-16

Prion diseases occur when the normally α-helical prion protein (PrP) converts to a pathological β-structured state with prion infectivity (PrP(Sc)). Exposure to PrP(Sc) from other mammals can catalyze this conversion. Evidence from experimental and accidental transmission of prions suggests that mammals vary in their prion disease susceptibility: Hamsters and mice show relatively high susceptibility, whereas rabbits, horses, and dogs show low susceptibility. Using a novel approach to quantify conformational states of PrP by circular dichroism (CD), we find that prion susceptibility tracks with the intrinsic propensity of mammalian PrP to convert from the native, α-helical state to a cytotoxic β-structured state, which exists in a monomer-octamer equilibrium. It has been controversial whether β-structured monomers exist at acidic pH; sedimentation equilibrium and dual-wavelength CD evidence is presented for an equilibrium between a β-structured monomer and octamer in some acidic pH conditions. Our X-ray crystallographic structure of rabbit PrP has identified a key helix-capping motif implicated in the low prion disease susceptibility of rabbits. Removal of this capping motif increases the β-structure folding propensity of rabbit PrP to match that of PrP from mouse, a species more susceptible to prion disease.

Genesis of mammalian prions: from non-infectious amyloid fibrils to a transmissible prion disease.

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Natallia Makarava

2011-12-01

Full Text Available The transmissible agent of prion disease consists of a prion protein in its abnormal, β-sheet rich state (PrP(Sc, which is capable of replicating itself according to the template-assisted mechanism. This mechanism postulates that the folding pattern of a newly recruited polypeptide chain accurately reproduces that of a PrP(Sc template. Here we report that authentic PrP(Sc and transmissible prion disease can be generated de novo in wild type animals by recombinant PrP (rPrP amyloid fibrils, which are structurally different from PrP(Sc and lack any detectable PrP(Sc particles. When induced by rPrP fibrils, a long silent stage that involved two serial passages preceded development of the clinical disease. Once emerged, the prion disease was characterized by unique clinical, neuropathological, and biochemical features. The long silent stage to the disease was accompanied by significant transformation in neuropathological properties and biochemical features of the proteinase K-resistant PrP material (PrPres before authentic PrP(Sc evolved. The current work illustrates that transmissible prion diseases can be induced by PrP structures different from that of authentic PrP(Sc and suggests that a new mechanism different from the classical templating exists. This new mechanism designated as "deformed templating" postulates that a change in the PrP folding pattern from the one present in rPrP fibrils to an alternative specific for PrP(Sc can occur. The current work provides important new insight into the mechanisms underlying genesis of the transmissible protein states and has numerous implications for understanding the etiology of neurodegenerative diseases.

Comparing the Folds of Prions and Other Pathogenic Amyloids

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José Miguel Flores-Fernández

2018-05-01

Full Text Available Pathogenic amyloids are the main feature of several neurodegenerative disorders, such as Creutzfeldt–Jakob disease, Alzheimer’s disease, and Parkinson’s disease. High resolution structures of tau paired helical filaments (PHFs, amyloid-β(1-42 (Aβ(1-42 fibrils, and α-synuclein fibrils were recently reported using cryo-electron microscopy. A high-resolution structure for the infectious prion protein, PrPSc, is not yet available due to its insolubility and its propensity to aggregate, but cryo-electron microscopy, X-ray fiber diffraction, and other approaches have defined the overall architecture of PrPSc as a 4-rung β-solenoid. Thus, the structure of PrPSc must have a high similarity to that of the fungal prion HET-s, which is part of the fungal heterokaryon incompatibility system and contains a 2-rung β-solenoid. This review compares the structures of tau PHFs, Aβ(1-42, and α-synuclein fibrils, where the β-strands of each molecule stack on top of each other in a parallel in-register arrangement, with the β-solenoid folds of HET-s and PrPSc.

Covalent surface modification of prions: a mass spectrometry-based means of detecting distinctive structural features of prion strains

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Prions (PrPSc) are molecular pathogens that are able to convert the isosequential normal cellular prion protein (PrPC) into a prion. The only demonstrated differences between PrPC and PrPSc is conformational, they are isoforms. A given host can be infected by more than one kind or strain of prion. F...

Molecular architecture of human prion protein amyloid: a parallel, in-register beta-structure.

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Cobb, Nathan J; Sönnichsen, Frank D; McHaourab, Hassane; Surewicz, Witold K

2007-11-27

Transmissible spongiform encephalopathies (TSEs) represent a group of fatal neurodegenerative diseases that are associated with conformational conversion of the normally monomeric and alpha-helical prion protein, PrP(C), to the beta-sheet-rich PrP(Sc). This latter conformer is believed to constitute the main component of the infectious TSE agent. In contrast to high-resolution data for the PrP(C) monomer, structures of the pathogenic PrP(Sc) or synthetic PrP(Sc)-like aggregates remain elusive. Here we have used site-directed spin labeling and EPR spectroscopy to probe the molecular architecture of the recombinant PrP amyloid, a misfolded form recently reported to induce transmissible disease in mice overexpressing an N-terminally truncated form of PrP(C). Our data show that, in contrast to earlier, largely theoretical models, the con formational conversion of PrP(C) involves major refolding of the C-terminal alpha-helical region. The core of the amyloid maps to C-terminal residues from approximately 160-220, and these residues form single-molecule layers that stack on top of one another with parallel, in-register alignment of beta-strands. This structural insight has important implications for understanding the molecular basis of prion propagation, as well as hereditary prion diseases, most of which are associated with point mutations in the region found to undergo a refolding to beta-structure.

Analysis of ADU structure obtained under different precipitation conditions

International Nuclear Information System (INIS)

Ramella, Jose L.; Esteban, Adolfo; Mendez De Leo, Lucia P.; Sassone, Ariel; Novara, Oscar E.; Boero, Norma L.; Leyva, Ana G.

1999-01-01

ADU is the nominal name for ammonium poly uranate. It is a very complex compound of polymeric structure, which may have, according to precipitation conditions, different chemical composition and crystallographic structure. ADU is used as uranium oxide precursor in the manufacture of fuel elements. In former papers it was proved that if ultrasound is applied during precipitation and digestion the characteristics of the final product (U 3 O 8 UO 2 ) improve. By studying ADU thermal decomposition obtained by ultrasonic application, it was intended to obtain its composition. Therefore, differential thermal gravimetric and differential thermal analyses were performed. Samples were taken from special points and analyzed by X-ray diffraction, infra-red spectroscopy and scanning. An experiment was also designed to identify the products released during heating. Results and conclusions obtained are presented in this work. (author)

Calcium binding promotes prion protein fragment 90-231 conformational change toward a membrane destabilizing and cytotoxic structure.

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Sacha Sorrentino

Full Text Available The pathological form of prion protein (PrP(Sc, as other amyloidogenic proteins, causes a marked increase of membrane permeability. PrP(Sc extracted from infected Syrian hamster brains induces a considerable change in membrane ionic conductance, although the contribution of this interaction to the molecular mechanism of neurodegeneration process is still controversial. We previously showed that the human PrP fragment 90-231 (hPrP₉₀₋₂₃₁ increases ionic conductance across artificial lipid bilayer, in a calcium-dependent manner, producing an alteration similar to that observed for PrP(Sc. In the present study we demonstrate that hPrP₉₀₋₂₃₁, pre-incubated with 10 mM Ca⁺⁺ and then re-suspended in physiological external solution increases not only membrane conductance but neurotoxicity as well. Furthermore we show the existence of a direct link between these two effects as demonstrated by a highly statistically significant correlation in several experimental conditions. A similar correlation between increased membrane conductance and cell degeneration has been observed assaying hPrP₉₀₋₂₃₁ bearing pathogenic mutations (D202N and E200K. We also report that Ca⁺⁺ binding to hPrP₉₀₋₂₃₁ induces a conformational change based on an alteration of secondary structure characterized by loss of alpha-helix content causing hydrophobic amino acid exposure and proteinase K resistance. These features, either acquired after controlled thermal denaturation or induced by D202N and E200K mutations were previously identified as responsible for hPrP₉₀₋₂₃₁ cytotoxicity. Finally, by in silico structural analysis, we propose that Ca⁺⁺ binding to hPrP₉₀₋₂₃₁ modifies amino acid orientation, in the same way induced by E200K mutation, thus suggesting a pathway for the structural alterations responsible of PrP neurotoxicity.

Plasminogen stimulates propagation of protease-resistant prion protein in vitro.

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Mays, Charles E; Ryou, Chongsuk

2010-12-01

To clarify the role of plasminogen as a cofactor for prion propagation, we conducted functional assays using a cell-free prion protein (PrP) conversion assay termed protein misfolding cyclic amplification (PMCA) and prion-infected cell lines. Here, we report that plasminogen stimulates propagation of the protease-resistant scrapie PrP (PrP(Sc)). Compared to control PMCA conducted without plasminogen, addition of plasminogen in PMCA using wild-type brain material significantly increased PrP conversion, with an EC(50) = ∼56 nM. PrP conversion in PMCA was substantially less efficient with plasminogen-deficient brain material than with wild-type material. The activity stimulating PrP conversion was specific for plasminogen and conserved in its kringle domains. Such activity was abrogated by modification of plasminogen structure and interference of PrP-plasminogen interaction. Kinetic analysis of PrP(Sc) generation demonstrated that the presence of plasminogen in PMCA enhanced the PrP(Sc) production rate to ∼0.97 U/μl/h and reduced turnover time to ∼1 h compared to those (∼0.4 U/μl/h and ∼2.5 h) obtained without supplementation. Furthermore, as observed in PMCA, plasminogen and kringles promoted PrP(Sc) propagation in ScN2a and Elk 21(+) cells. Our results demonstrate that plasminogen functions in stimulating conversion processes and represents the first cellular protein cofactor that enhances the hypothetical mechanism of prion propagation.

Prions amplify through degradation of the VPS10P sorting receptor sortilin.

Science.gov (United States)

Uchiyama, Keiji; Tomita, Mitsuru; Yano, Masashi; Chida, Junji; Hara, Hideyuki; Das, Nandita Rani; Nykjaer, Anders; Sakaguchi, Suehiro

2017-06-01

Prion diseases are a group of fatal neurodegenerative disorders caused by prions, which consist mainly of the abnormally folded isoform of prion protein, PrPSc. A pivotal pathogenic event in prion disease is progressive accumulation of prions, or PrPSc, in brains through constitutive conformational conversion of the cellular prion protein, PrPC, into PrPSc. However, the cellular mechanism by which PrPSc is progressively accumulated in prion-infected neurons remains unknown. Here, we show that PrPSc is progressively accumulated in prion-infected cells through degradation of the VPS10P sorting receptor sortilin. We first show that sortilin interacts with PrPC and PrPSc and sorts them to lysosomes for degradation. Consistently, sortilin-knockdown increased PrPSc accumulation in prion-infected cells. In contrast, overexpression of sortilin reduced PrPSc accumulation in prion-infected cells. These results indicate that sortilin negatively regulates PrPSc accumulation in prion-infected cells. The negative role of sortilin in PrPSc accumulation was further confirmed in sortilin-knockout mice infected with prions. The infected mice had accelerated prion disease with early accumulation of PrPSc in their brains. Interestingly, sortilin was reduced in prion-infected cells and mouse brains. Treatment of prion-infected cells with lysosomal inhibitors, but not proteasomal inhibitors, increased the levels of sortilin. Moreover, sortilin was reduced following PrPSc becoming detectable in cells after infection with prions. These results indicate that PrPSc accumulation stimulates sortilin degradation in lysosomes. Taken together, these results show that PrPSc accumulation of itself could impair the sortilin-mediated sorting of PrPC and PrPSc to lysosomes for degradation by stimulating lysosomal degradation of sortilin, eventually leading to progressive accumulation of PrPSc in prion-infected cells.

Reversible unfolding of infectious prion assemblies reveals the existence of an oligomeric elementary brick.

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Angélique Igel-Egalon

2017-09-01

Full Text Available Mammalian prions, the pathogens that cause transmissible spongiform encephalopathies, propagate by self-perpetuating the structural information stored in the abnormally folded, aggregated conformer (PrPSc of the host-encoded prion protein (PrPC. To date, no structural model related to prion assembly organization satisfactorily describes how strain-specified structural information is encoded and by which mechanism this information is transferred to PrPC. To achieve progress on this issue, we correlated the PrPSc quaternary structural transition from three distinct prion strains during unfolding and refolding with their templating activity. We reveal the existence of a mesoscopic organization in PrPSc through the packing of a highly stable oligomeric elementary subunit (suPrP, in which the strain structural determinant (SSD is encoded. Once kinetically trapped, this elementary subunit reversibly loses all replicative information. We demonstrate that acquisition of the templating interface and infectivity requires structural rearrangement of suPrP, in concert with its condensation. The existence of such an elementary brick scales down the SSD support to a small oligomer and provide a basis of reflexion for prion templating process and propagation.

Piperazine derivatives inhibit PrP/PrP(res) propagation in vitro and in vivo.

Science.gov (United States)

Leidel, Fabienne; Eiden, Martin; Geissen, Markus; Hirschberger, Thomas; Tavan, Paul; Giese, Armin; Kretzschmar, Hans A; Schätzl, Hermann; Groschup, Martin H

2014-02-28

Prion diseases are fatal neurodegenerative disorders, which are not curable and no effective treatment exists so far. The major neuropathological change in diseased brains is the conversion of the normal cellular form of the prion protein PrPc(C) into a disease-associated isoform PrP(Sc). PrP(Sc) accumulates into multimeres and fibrillar aggregates, which leads to the formation of amyloid plaques. Increasing evidence indicates a fundamental role of PrP(Sc) species and its aggregation in the pathogenesis of prion diseases, which initiates the pathological cascade and leads to neurodegeneration accompanied by spongiform changes. In search of compounds that have the potential to interfere with PrP(Sc) formation and propagation, we used a cell based assay for the screening of potential aggregation inhibitors. The assay deals with a permanently prion infected cell line that was adapted for a high-throughput screening of a compound library composed of 10,000 compounds (DIVERset 2, ChemBridge). We could detect six different classes of highly potent inhibitors of PrP(Sc) propagation in vitro and identified piperazine derivatives as a new inhibitory lead structure, which increased incubation time of scrapie infected mice. Copyright © 2014 Elsevier Inc. All rights reserved.

Protease resistance of infectious prions is suppressed by removal of a single atom in the cellular prion protein.

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Leske, Henning; Hornemann, Simone; Herrmann, Uli Simon; Zhu, Caihong; Dametto, Paolo; Li, Bei; Laferriere, Florent; Polymenidou, Magdalini; Pelczar, Pawel; Reimann, Regina Rose; Schwarz, Petra; Rushing, Elisabeth Jane; Wüthrich, Kurt; Aguzzi, Adriano

2017-01-01

Resistance to proteolytic digestion has long been considered a defining trait of prions in tissues of organisms suffering from transmissible spongiform encephalopathies. Detection of proteinase K-resistant prion protein (PrPSc) still represents the diagnostic gold standard for prion diseases in humans, sheep and cattle. However, it has become increasingly apparent that the accumulation of PrPSc does not always accompany prion infections: high titers of prion infectivity can be reached also in the absence of protease resistant PrPSc. Here, we describe a structural basis for the phenomenon of protease-sensitive prion infectivity. We studied the effect on proteinase K (PK) resistance of the amino acid substitution Y169F, which removes a single oxygen atom from the β2-α2 loop of the cellular prion protein (PrPC). When infected with RML or the 263K strain of prions, transgenic mice lacking wild-type (wt) PrPC but expressing MoPrP169F generated prion infectivity at levels comparable to wt mice. The newly generated MoPrP169F prions were biologically indistinguishable from those recovered from prion-infected wt mice, and elicited similar pathologies in vivo. Surprisingly, MoPrP169F prions showed greatly reduced PK resistance and density gradient analyses showed a significant reduction in high-density aggregates. Passage of MoPrP169F prions into mice expressing wt MoPrP led to full recovery of protease resistance, indicating that no strain shift had taken place. We conclude that a subtle structural variation in the β2-α2 loop of PrPC affects the sensitivity of PrPSc to protease but does not impact prion replication and infectivity. With these findings a specific structural feature of PrPC can be linked to a physicochemical property of the corresponding PrPSc.

Structure of Al-CF composites obtained by infiltration methods

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A. Dolata-Grosz

2011-04-01

Full Text Available The structure of the composites obtained in infiltration processes 2D and 3D carbon preform by liquid Al alloy have been presented in thispaper. An aluminum alloy with silicon and manganese AlSi9Mn (trimal 37-TR37 was applied in the researches. As the reinforcementused carbon perform prepared with various protective barriers such as the nickel coating, the coating of silicon carbide and pyrolyticcarbon coating. Carbon preforms was prepared at the Institute for Lightweight Structures and Polymer Technology (ILK TU Dresden andat the Institute of Technology and Ceramic Systems (Fraunhofer-IKTS. The process of infiltration of carbon perform by liquid aluminiumalloy was carried out using a pressure-vacuum infiltration on the Degussa press and gas-pressure infiltration (GPI in an autoclavedesigned and built at the Department of Materials Technology at the Silesian University of Technology. The obtained composites werecharacterized by a regular shape, with no surface casting defects. The best connection of components was observed in AlSi9Mn/Cf(Nicomposite, obtained by gas-pressure infiltration method (GPI. On metallographic specimens, good interface between fibres and thealuminium matrix were observed. The obtained research results justify the application of nickel coatings on the fibres. During the failurecrack propagated across fiber. There was no presence of aluminum carbide on the fiber-matrix. It can be assumed that the composite willbe characterized by the good mechanical properties. However, this requires further experimental verification planned in the next stage of research, in the project realized within the DFG program: "3D textile reinforced aluminium matrix composites for complex loadingsituations in lightweight automobile and machine parts".

Structure and thermal properties of nanospheres obtained by ethoxy silanes copolymerization

International Nuclear Information System (INIS)

Pedroso, Marcos A.S.; Mothe, Cheila G.; Dias, Marcos L.

2001-01-01

Thermal and structural characterization of organophylic nano spherical copolymers of tetra ethoxysilane (TEOS) and methyltriethoxysilane (MTEOS) or dimethyldiethoxysilane (DMDEOS) obtained by sol-gel reaction terminated by trimethylchlorosilane are described. 29 Si NMR, wide angle X-ray scattering (WAXS) and thermal analysis (TG/DTG and DTA) were employed. Due to the high reactivity of TEOS, the copolymers are silica-silicon hybrids showing bilayer structure where silica constitutes a core and a alkyl-rich chemical structure constitutes the external layer. The copolymers present higher mass lost at high temperatures than TEOS homopolymer. (author)

Structural investigations of zirconia powders obtained by hf-plasmochemical denitration

International Nuclear Information System (INIS)

Dedov, N.V.; Ivanov, Yu.F.; Dorda, F.A.; Paul', A.V.; Zav'yalov, A.V.; Koneva, N.A.; Korobtsev, V.P.; Kutyavin, E.M.; Mazin, V.I.; Matyukha, V.A.

1992-01-01

Results are presented of structural and physicochemical investigations of unstabilized and stabilized (using yttria, magnesia, calcium oxide and alumina) zirconia, obtained from nitrate solutions on pilot HF-plasmochemical equipment with an electric rating of 63 kW. The phase composition of the ultradispersed powder is shown. Morphological and grain-size analyses were carried out on the EM-125K electron diffraction microscope. specimens were prepared by applying powder to a carbon film obtained in a VUP-4 vacuum cell. The phase composition was studied by x-ray analysis on the DRON-3 diffractometer. These studies established that the main morphological constituents of the ZrO 2 powder are polycrystalline hollow spheres and fragments of films. The average sizes (diameter) of the spheres in 0.77 μ (mean square deviation σ n = 0.57μ) and for the grains in them 31 nm (σ n = 9.5 nm). There exists a certain correlation between the dimensions of the polycrystalline spheres and their grain structure - the coarser the powders, the larger the grains observed

Structure, morphology and thermal stability of electrochemically obtained Ni-Co deposits

Energy Technology Data Exchange (ETDEWEB)

Rafailovic, L.D. [Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Artner, W. [Centre of Electrochemical Surface Technology (CEST), Viktor-Kaplan-Strasse 2, A-2700 Wr. Neustadt (Austria); Nauer, G.E. [Centre of Electrochemical Surface Technology (CEST), Viktor-Kaplan-Strasse 2, A-2700 Wr. Neustadt (Austria); Faculty of Chemistry, University of Vienna, Waehringer Strasse 42, A-1090 Vienna (Austria); Minic, D.M., E-mail: dminic@ffh.bg.ac.rs [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12, 11000 Belgrade (Serbia)

2009-12-10

Nanostructured nickel-cobalt alloy powder deposits were obtained electrochemically on Cu substrates in the current density range 40-400 mA cm{sup -2}. The influence of the current density and of the Ni{sup 2+}/Co{sup 2+} ratio in the bath on the microstructure and phase composition of the Ni-Co deposits was studied by SEM and X-ray diffraction methods. Both the bath composition and the current density strongly influence the deposit growth mechanism as well as the deposit composition, microstructure, grain size and surface morphology. If the concentration ratio in the electrolyte is Ni{sup 2+}/Co{sup 2+} = 4, the deposit has a cauliflower structure with mean grain size of 13 nm. In contrast, the particles deposited from the electrolyte with Ni{sup 2+}/Co{sup 2+} = 0.25 show platelet structure with preferred orientations and mean grain size of 20 nm. When electrodeposition was performed at high overpotentials, far from equilibrium conditions, face-centered cubic (FCC) solid solutions of Ni and Co were generated while at low overpotentials, as well as at higher content of cobalt in the electrolyte, hexagonal-close packed (HCP) Co was formed. The structure of nanocrystalline deposits exhibits a strong tendency to structural changes under annealing. DSC of the alloy deposits shows a stepwise process of structural changes in the temperature range from 393 to 823 K. It was found that under annealing, HCP {yields} FCC phase transformation occurs in nanocrystalline deposit obtained from electrolyte with a concentration ratio Ni{sup 2+}/Co{sup 2+} = 0.25.

Fine defective structure of silicon carbide powders obtained from different starting materials

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Tomila T.V.

2006-01-01

Full Text Available The fine defective structure of silicon carbide powders obtained from silicic acid-saccharose, aerosil-saccharose, aerosil-carbon black, and hydrated cellulose-silicic acid gel systems was investigated. The relation between IR absorption characteristics and the microstructure of SiC particles obtained from different starting materials was established. The numerical relationship between the lattice parameter a and the frequency νTO is presented.

Intraepithelial and interstitial deposition of pathological prion protein in kidneys of scrapie-affected sheep.

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Ciriaco Ligios

Full Text Available Prions have been documented in extra-neuronal and extra-lymphatic tissues of humans and various ruminants affected by Transmissible Spongiform Encephalopathy (TSE. The presence of prion infectivity detected in cervid and ovine blood tempted us to reason that kidney, the organ filtrating blood derived proteins, may accumulate disease associated PrP(Sc. We collected and screened kidneys of experimentally, naturally scrapie-affected and control sheep for renal deposition of PrP(Sc from distinct, geographically separated flocks. By performing Western blot, PET blot analysis and immunohistochemistry we found intraepithelial (cortex, medulla and papilla and occasional interstitial (papilla deposition of PrP(Sc in kidneys of scrapie-affected sheep. Interestingly, glomerula lacked detectable signals indicative of PrP(Sc. PrP(Sc was also detected in kidneys of subclinical sheep, but to significantly lower degree. Depending on the stage of the disease the incidence of PrP(Sc in kidney varied from approximately 27% (subclinical to 73.6% (clinical in naturally scrapie-affected sheep. Kidneys from flocks without scrapie outbreak were devoid of PrP(Sc. Here we demonstrate unexpectedly frequent deposition of high levels of PrP(Sc in ovine kidneys of various flocks. Renal deposition of PrP(Sc is likely to be a pre-requisite enabling prionuria, a possible co-factor of horizontal prion-transmission in sheep.

Crystal structure of TiNi nanoparticles obtained by Ar ion beam deposition

International Nuclear Information System (INIS)

Castro, A. Torres; Cuellar, E. Lopez; Mendez, U. Ortiz; Yacaman, M. Jose

2008-01-01

Nanoparticles are a state of matter that have properties different from either molecules or bulk solids, turning them into a very interesting class of materials to study. In the present work, the crystal structure of TiNi nanoparticles obtained by ion beam deposition is characterized. TiNi nanoparticles were obtained from TiNi wire samples by sputtering with Ar ions using a Gatan precision ion polishing system. The TiNi nanoparticles were deposited on a Lacey carbon film that was used for characterization by transmission electron microscopy. The nanoparticles were characterized by high-resolution transmission electron microscopy, high-angle annular dark-field imaging, electron diffraction, scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. Results of nanodiffraction seem to indicate that the nanoparticles keep the same B2 crystal structure as the bulk material but with a decreased lattice parameter

The Distribution of Prion Protein Allotypes Differs Between Sporadic and Iatrogenic Creutzfeldt-Jakob Disease Patients.

Science.gov (United States)

Moore, Roger A; Head, Mark W; Ironside, James W; Ritchie, Diane L; Zanusso, Gianluigi; Choi, Young Pyo; Pyo Choi, Young; Priola, Suzette A

2016-02-01

Sporadic Creutzfeldt-Jakob disease (sCJD) is the most prevalent of the human prion diseases, which are fatal and transmissible neurodegenerative diseases caused by the infectious prion protein (PrP(Sc)). The origin of sCJD is unknown, although the initiating event is thought to be the stochastic misfolding of endogenous prion protein (PrP(C)) into infectious PrP(Sc). By contrast, human growth hormone-associated cases of iatrogenic CJD (iCJD) in the United Kingdom (UK) are associated with exposure to an exogenous source of PrP(Sc). In both forms of CJD, heterozygosity at residue 129 for methionine (M) or valine (V) in the prion protein gene may affect disease phenotype, onset and progression. However, the relative contribution of each PrP(C) allotype to PrP(Sc) in heterozygous cases of CJD is unknown. Using mass spectrometry, we determined that the relative abundance of PrP(Sc) with M or V at residue 129 in brain specimens from MV cases of sCJD was highly variable. This result is consistent with PrP(C) containing an M or V at residue 129 having a similar propensity to misfold into PrP(Sc) thus causing sCJD. By contrast, PrP(Sc) with V at residue 129 predominated in the majority of the UK human growth hormone associated iCJD cases, consistent with exposure to infectious PrP(Sc) containing V at residue 129. In both types of CJD, the PrP(Sc) allotype ratio had no correlation with CJD type, age at clinical onset, or disease duration. Therefore, factors other than PrP(Sc) allotype abundance must influence the clinical progression and phenotype of heterozygous cases of CJD.

Structural Studies of Silver Nanoparticles Obtained Through Single-Step Green Synthesis

Science.gov (United States)

Prasad Peddi, Siva; Abdallah Sadeh, Bilal

2015-10-01

Green synthesis of silver Nanoparticles (AGNP's) has been the most prominent among the metallic nanoparticles for research for over a decade and half now due to both the simplicity of preparation and the applicability of biological species with extensive applications in medicine and biotechnology to reduce and trap the particles. The current article uses Eclipta Prostrata leaf extract as the biological species to cap the AGNP's through a single step process. The characterization data obtained was used for the analysis of the sample structure. The article emphasizes the disquisition of their shape and size of the lattice parameters and proposes a general scheme and a mathematical model for the analysis of their dependence. The data of the synthesized AGNP's has been used to advantage through the introduction of a structural shape factor for the crystalline nanoparticles. The properties of the structure of the AGNP's proposed and evaluated through a theoretical model was undeviating with the experimental consequences. This modus operandi gives scope for the structural studies of ultrafine particles prepared using biological methods.

The effective fracture toughness of structural components obtained with the blend rule

International Nuclear Information System (INIS)

Eriksson, K.

1998-01-01

The blend rule for the effective fracture toughness of a layered material was originally derived from the special case of a through crack in a globally elastic material and later extended to accomodate non-linear behaviour. It is now derived from a general case by considering material elements of finite size and of different toughness along and around the tip of a crack. Experimental results obtained with an inhomogeneous ordinary structural steel which support the blend rule are presented. It is shown that the effective fracture toughness governs the load-bearing capacity of a cracked full-scale structure. Some further results found in the literature for the heat-affected zone material of a high-strength microalloyed quenched and tempered structural steel and computational results for a structural steel typical of a nuclear pressure vessel are shown to support the blend rule. (orig.)

Investigation of the effects of experimental autolysis on the detection of abnormal prion protein in lymphoid and central nervous system tissues from elk and sheep using the Western blotting method.

Science.gov (United States)

Huang, Hongsheng; Soutyrine, Andrei; Rendulich, Jasmine; O'Rourke, Katherine; Balachandran, Aru

2011-01-01

Tissues unsuitable for standard immunohistochemical and histopathological examinations for chronic wasting disease (CWD) in cervids and for scrapie in sheep are frequently submitted for testing. This study investigated the effects of experimental autolysis on the detection of abnormal prion protein (PrPsc) in lymphoid and central nervous system (CNS) tissues from elk and sheep. The PrPsc was detected using a Western blotting (WB) test following PrPsc enrichment using sodium phosphotungstic acid (PTA) precipitation (PTA-WB). A commercial enzyme-linked immunosorbent assay (ELISA) was used as a reference test for quantitative measurement. This study showed that the amount of PrPsc in lymphoid and CNS tssues from elk and sheep decreased gradually as a result of autolysis, but PrPsc was still detectable after 5 and 15 d incubation at 37°C by PTA-WB for all lymphoid and CNS samples. The results of the ELISA supported those of PTA-WB, particularly for CNS tissues. In conclusion, autolysis at 37°C for 15 d would not significantly affect the detection of PrPsc in lymphoid and CNS tissues by WB and ELISA and, particularly, PTA-WB is a valuable and alternative confirmatory test to detect PrPsc in autolyzed lymphoid and CNS samples.

Strain-dependent profile of misfolded prion protein aggregates.

Science.gov (United States)

Morales, Rodrigo; Hu, Ping Ping; Duran-Aniotz, Claudia; Moda, Fabio; Diaz-Espinoza, Rodrigo; Chen, Baian; Bravo-Alegria, Javiera; Makarava, Natallia; Baskakov, Ilia V; Soto, Claudio

2016-02-15

Prions are composed of the misfolded prion protein (PrP(Sc)) organized in a variety of aggregates. An important question in the prion field has been to determine the identity of functional PrP(Sc) aggregates. In this study, we used equilibrium sedimentation in sucrose density gradients to separate PrP(Sc) aggregates from three hamster prion strains (Hyper, Drowsy, SSLOW) subjected to minimal manipulations. We show that PrP(Sc) aggregates distribute in a wide range of arrangements and the relative proportion of each species depends on the prion strain. We observed a direct correlation between the density of the predominant PrP(Sc) aggregates and the incubation periods for the strains studied. The relative presence of PrP(Sc) in fractions of different sucrose densities was indicative of the protein deposits present in the brain as analyzed by histology. Interestingly, no association was found between sensitivity to proteolytic degradation and aggregation profiles. Therefore, the organization of PrP molecules in terms of the density of aggregates generated may determine some of the particular strain properties, whereas others are independent from it. Our findings may contribute to understand the mechanisms of strain variation and the role of PrP(Sc) aggregates in prion-induced neurodegeneration.

The POM monoclonals: a comprehensive set of antibodies to non-overlapping prion protein epitopes.

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Magdalini Polymenidou

Full Text Available PrP(Sc, a misfolded and aggregated form of the cellular prion protein PrP(C, is the only defined constituent of the transmissible agent causing prion diseases. Expression of PrP(C in the host organism is necessary for prion replication and for prion neurotoxicity. Understanding prion diseases necessitates detailed structural insights into PrP(C and PrP(Sc. Towards this goal, we have developed a comprehensive collection of monoclonal antibodies denoted POM1 to POM19 and directed against many different epitopes of mouse PrP(C. Three epitopes are located within the N-terminal octarepeat region, one is situated within the central unstructured region, and four epitopes are discontinuous within the globular C-proximal domain of PrP(C. Some of these antibodies recognize epitopes that are resilient to protease digestion in PrP(Sc. Other antibodies immunoprecipitate PrP(C, but not PrP(Sc. A third group was found to immunoprecipitate both PrP isoforms. Some of the latter antibodies could be blocked with epitope-mimicking peptides, and incubation with an excess of these peptides allowed for immunochromatography of PrP(C and PrP(Sc. Amino-proximal antibodies were found to react with repetitive PrP(C epitopes, thereby vastly increasing their avidity. We have also created functional single-chain miniantibodies from selected POMs, which retained the binding characteristics despite their low molecular mass. The POM collection, thus, represents a unique set of reagents allowing for studies with a variety of techniques, including western blotting, ELISA, immunoprecipitation, conformation-dependent immunoassays, and plasmon surface plasmon resonance-based assays.

Immunohistochemical detection of prion protein in lymphoid tissues of sheep with natural scrapie

NARCIS (Netherlands)

Keulen, van L.J.M.; Schreuder, B.E.C.; Meloen, R.H.; Mooij-Harkes, G.; Vromans, M.E.W.; Langeveld, J.P.M.

1996-01-01

The scrapie-associated form of the prion protein (PrP(Sc)) accumulates in the brain and lymphoid tissues of sheep with scrapie. In order to assess whether detecting PrP(Sc) in lymphoid tissue could he used as a diagnostic test for scrapie, we studied the localization and distribution of PrP(Sc) in

Structural characterization of hog iron oxide content glasses obtained from zinc hydrometallurgy wastes

International Nuclear Information System (INIS)

Romero, M.; Rincon, J.M.; Musik, S.; Kozhujharov, W.

1997-01-01

It has been carried out the structural characterization of high oxide content glasses obtained by melting of a goethite industrial waste from the zinc hydrometallurgy with other raw materials as dolomite and glass cullet. The structural characterization has been carried out by X-ray Diffraction (XRD), X-Ray Diffraction by Amorphous Dispersion (RDF) and Mossbauer spectroscopy. It has been determined the interatomic distance, the oxidation state and the coordination of iron atoms in these glasses. (Author) 16 refs

Relationship between magnetism and prion protein

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F. Balzano

2010-01-01

Full Text Available The mechanism of conversion of the normal prion protein (PrPC into aggregates of its pathological conformer (PrPSc reamins unclear. The aim of this study was to evaluate the effects induced by exposure of biological samples containing PrPSC to a magnetic field induced prominent molecular changes of samples indicated by the IR spectra located in the region that contains contribution primarily from absorption of amides. This finding suggests the existence of a strong correlation between magnetism and PrPsc and supports a new hypothesis that explains the conversion of normal PrPc to abnormal isoform PrPsc.

Pathogenesis of bovine spongiform encephalopathy in sheep.

Science.gov (United States)

van Keulen, L J M; Vromans, M E W; Dolstra, C H; Bossers, A; van Zijderveld, F G

2008-01-01

The pathogenesis of bovine spongiform encephalopathy (BSE) in sheep was studied by immunohistochemical detection of scrapie-associated prion protein (PrP(Sc)) in the gastrointestinal, lymphoid and neural tissues following oral inoculation with BSE brain homogenate. First accumulation of PrP(Sc) was detected after 6 months in the tonsil and the ileal Peyer's patches. At 9 months postinfection, PrP(Sc) accumulation involved all gut-associated lymphoid tissues and lymph nodes as well as the spleen. At this time point, PrP(Sc) accumulation in the peripheral neural tissues was first seen in the enteric nervous system of the caudal jejunum and ileum and in the coeliac-mesenteric ganglion. In the central nervous system, PrP(Sc) was first detected in the dorsal motor nucleus of the nervus Vagus in the medulla oblongata and in the intermediolateral column in the spinal cord segments T7-L1. At subsequent time points, PrP(Sc) was seen to spread within the lymphoid system to also involve all non-gut-associated lymphoid tissues. In the enteric nervous system, further spread of PrP(Sc) involved the neural plexi along the entire gastrointestinal tract and in the CNS the complete neuraxis. These findings indicate a spread of the BSE agent in sheep from the enteric nervous system through parasympathetic and sympathetic nerves to the medulla oblongata and the spinal cord.

Structural study of some gadolinium glass ceramics obtained by sol-gel method

International Nuclear Information System (INIS)

Coroiu, Ilioara; Simiti, Vida I.; Bratu, I.; Borodi, Gh.; Darabont, Al.

2004-01-01

Increased interest in silicate systems containing different rare earth oxides has resulted from their important applications in various fields of technology including laser, optical fiber and optical waveguides in telecommunication applications, microelectronics and catalysis. Glass-ceramics of 0.95 SiO 2 -0.05 Na 2 O composition containing up to 15% molar Gd 2 O 3 were obtained by the sol-gel method. We chose the sol-gel method because this offers the advantage of a good chemical homogeneity and a better control of physical and chemical properties in comparison with traditional methods used to obtain glasses and ceramics. The obtained samples were pressed at 200 kgf/cm 2 as disks with a diameter of Φ=22 mm and a thickness of around 1 mm. Then, they were heat-treated at 250 deg C, 500 deg C and 1000 deg C for about 48 hours. The structural study was made using X-ray diffraction, scanning electron microscopy (SEM) and IR spectroscopy. The X-ray diffraction patterns show that addition of Gd 2 O 3 exerts an important influence on the crystallization process of the studied samples. The crystalline phase decreases with increasing the Gd 2 O 3 concentration. SEM data support this assertion. IR spectra point out also that the increasing of the gadolinium oxide content and the thermal treatment temperature produce the strengthening of the glass ceramic network. Thus, the gadolinium ions play the role of network modifier of the glass ceramic structure. (authors)

The structure of Cu-Cd alloys obtained by electrolysis on monocrystalline silver substrates

International Nuclear Information System (INIS)

Lagiewka, E.

1981-01-01

The structure of Cu-Cd alloys obtained by electrolysis on monocrystalline silver cathodes with a surface parallel to the (111), (110) and (100) planes has been investigated. It has been found that depending on the range of the cathode potentials, one-phase (phase α) or two-phase (phase α + cadmium) alloy are obtained. In the alloys the occurrence of twins has been observed, the orientation of which is the result of twinning along the [111] planes of crystallites with epitaxial orientation with respect to the cathode surface and of a random orientation of crystallites. The volume of the layer containing crystallites with a random arrangement increases with the obtaining potential of the alloy and with the decrease in the surface density of the cathode atoms. (author)

ZnO nanoparticles obtained by ball milling technique: Structural, micro-structure, optical and photo-catalytic properties

Energy Technology Data Exchange (ETDEWEB)

Balamurugan, S., E-mail: scandium.chemistry@gmail.com; Joy, Josny; Godwin, M. Anto; Selvamani, S.; Raja, T. S. Gokul [Advanced Nanomaterials Research Laboratory, Department of Nanotechnology, Noorul Islam Centre for Higher Education, Thuckalay, Kumaracoil - 629 180 (India)

2016-05-23

The ZnO nanoparticles were obtained by ball milling of commercial grade ZnO powder at 250 rpm for 20 h and studied their structural, micro-structure, optical and photo-catalytic properties. Due to ball milling significant decrease in lattice parameters and average crystalline size is noticed for the as-milled ZnO nano powder. The HRSEM images of the as-milled powder consist of agglomerated fine spherical nanoparticles in the range of ~10-20 nm. The room temperature PL spectrum of as-milled ZnO nano powder excited under 320 nm reveals two emission bands at ~406 nm (violet emission) and ~639 nm (green emission). Interestingly about 98 % of photo degradation of methylene (MB) by the ZnO catalyst is achieved at 100 minutes of solar light irradiation.

Obtaining of bilateral high voltage epitaxial p—i—n Si structures by LPE method

Directory of Open Access Journals (Sweden)

Vakiv N. M.

2013-12-01

Full Text Available Silicon p—i—n-structures are usually obtained using conventional diffusion method or liquid phase epitaxy (LPE. In both cases, the formation of p- and n-layers occurs in two stages. This technological approach is quite complex. Moreover, when forming bilateral high-voltage epitaxial layers, their parameters significantly deteriorate as a result of prolonged heat treatment of active high-resistivity layer. Besides, when using diffusion method, it is impossible to provide good reproducibility of the process. In this paper a technique of growing bilateral high-voltage silicon p—i—n-structures by LPE in a single process is proposed. The authors have obtained the optimum compounds of silicon-undersaturated molten solutions for highly doped (5•1018 cm–3 contact layers: 0.4—0.8 at. % aluminum in gallium melt for growing p-Si-layers and 0.03—0.15 at. % ytterbium in tin melt for n-Si-layers. Parameters of such structures provide for manufacturing of high-voltage diodes on their basis. Such diodes can be used in navigational equipment, communication systems for household and special purposes, on-board power supply systems, radar systems, medical equipment, etc.

Cryo-immunogold electron microscopy for prions: toward identification of a conversion site.

Science.gov (United States)

Godsave, Susan F; Wille, Holger; Kujala, Pekka; Latawiec, Diane; DeArmond, Stephen J; Serban, Ana; Prusiner, Stanley B; Peters, Peter J

2008-11-19

Prion diseases are caused by accumulation of an abnormally folded isoform (PrP(Sc)) of the cellular prion protein (PrP(C)). The subcellular distribution of PrP(Sc) and the site of its formation in brain are still unclear. We performed quantitative cryo-immunogold electron microscopy on hippocampal sections from mice infected with the Rocky Mountain Laboratory strain of prions. Two antibodies were used: R2, which recognizes both PrP(C) and PrP(Sc); and F4-31, which only detects PrP(C) in undenatured sections. At a late subclinical stage of prion infection, both PrP(C) and PrP(Sc) were detected principally on neuronal plasma membranes and on vesicles resembling early endocytic or recycling vesicles in the neuropil. The R2 labeling was approximately six times higher in the infected than the uninfected hippocampus and gold clusters were only evident in infected tissue. The biggest increase in labeling density (24-fold) was found on the early/recycling endosome-like vesicles of small-diameter neurites, suggesting these as possible sites of conversion. Trypsin digestion of infected hippocampal sections resulted in a reduction in R2 labeling of >85%, which suggests that a high proportion of PrP(Sc) may be oligomeric, protease-sensitive PrP(Sc).

Structure and properties of composite iron-based coatings obtained by the electromechanical technique

Science.gov (United States)

Dubinskii, N. A.

2007-09-01

The influence of the electrolyte temperature and current density on the content of inclusions of powder particles in composite coatings obtained by the electrochemical technique has been investigated. It has been found that the wear resistance of iron coatings with inclusions of powder particles of aluminum, kaolin, and calcium silicate increases from 5 to 10 times compared to coating without inclusions of disperse particles, and the friction coefficient therewith decreases from 0.097 to 0.026. It has been shown that the mechanical properties of iron obtained by the method of electrochemical deposition depend on their fine structure. The regimes of deposition of iron-based coatings have been optimized.

Amidation and structure relaxation abolish the neurotoxicity of the prion peptide PrP106-126 in vivo and in vitro

DEFF Research Database (Denmark)

Bergstrøm, Linda Alice; Hvass, Henriette Cordes; Zsurger, N.

2005-01-01

One of the major pathological hallmarks of transmissible spongiform encephalopathies (TSEs) is the accumulation of a pathogenic (scrapie) isoform (PrPSc) of the cellular prion protein (PrPC) primarily in the central nervous system. The synthetic prion peptide PrP106-126 shares many characteristics...

The chemistry and structure of nickel–tungsten coatings obtained by pulse galvanostatic electrodeposition

International Nuclear Information System (INIS)

Argañaraz, M.P. Quiroga; Ribotta, S.B.; Folquer, M.E.; Zelaya, E.; Llorente, C.; Ramallo-López, J.M.; Benítez, G.; Rubert, A.; Gassa, L.M.; Vela, M.E.; Salvarezza, R.C.

2012-01-01

A detailed characterization of electrodeposited Ni-W coatings prepared by pulse electrodeposition on steel and copper substrates is presented. The coatings were obtained at high current pulse frequency and show high microhardness and absence of brittleness. The surface of the coating consists of nanometer sized crystals forming a cauliflower-like structure protected by a mixture of nickel and tungsten oxides. The cauliflower structure is preserved into the bulk coating that exhibits an average composition ≈70 at% Ni-30 at% W. Different phases are observed in the bulk structure: a W-rich amorphous phase (≈40%) and Ni-rich crystalline phases (≈60%). The crystalline phases consist of crystalline domains ≈7 nm in size of Ni(W) (fcc) solid solution (12 at% W content) and a minor Ni 4 W component (less than 10%). The amorphous phase exhibits a less compact Ni-W structure where some amount of C could also be present. Oxidized W species cannot be detected in the bulk coating, thus discarding the presence of significant amounts of tungsten carbide, tungstates or citrate–tungsten complexes. Our results shed light on controversial points related to the chemical composition and demonstrate the complex structure of this system.

High-Throughput Screening of Compounds for Anti-Transmissible Spongiform Encephalopathy Activity Using Cell-Culture and Cell-Free Models and Infected Animals

National Research Council Canada - National Science Library

Caughey, Byron

2006-01-01

.... One therapeutic approach is the inhibitors of PrPSc accumulation indeed many inhibitors of PrPSc accumulation in scrapie-infected cells also have anti-scrapie activity in rodents During This year...

Discovery of small molecules binding to the normal conformation of prion by combining virtual screening and multiple biological activity evaluation methods

Science.gov (United States)

Li, Lanlan; Wei, Wei; Jia, Wen-Juan; Zhu, Yongchang; Zhang, Yan; Chen, Jiang-Huai; Tian, Jiaqi; Liu, Huanxiang; He, Yong-Xing; Yao, Xiaojun

2017-12-01

Conformational conversion of the normal cellular prion protein, PrPC, into the misfolded isoform, PrPSc, is considered to be a central event in the development of fatal neurodegenerative diseases. Stabilization of prion protein at the normal cellular form (PrPC) with small molecules is a rational and efficient strategy for treatment of prion related diseases. However, few compounds have been identified as potent prion inhibitors by binding to the normal conformation of prion. In this work, to rational screening of inhibitors capable of stabilizing cellular form of prion protein, multiple approaches combining docking-based virtual screening, steady-state fluorescence quenching, surface plasmon resonance and thioflavin T fluorescence assay were used to discover new compounds interrupting PrPC to PrPSc conversion. Compound 3253-0207 that can bind to PrPC with micromolar affinity and inhibit prion fibrillation was identified from small molecule databases. Molecular dynamics simulation indicated that compound 3253-0207 can bind to the hotspot residues in the binding pocket composed by β1, β2 and α2, which are significant structure moieties in conversion from PrPC to PrPSc.

Recombinant human prion protein inhibits prion propagation in vitro.

Science.gov (United States)

Yuan, Jue; Zhan, Yi-An; Abskharon, Romany; Xiao, Xiangzhu; Martinez, Manuel Camacho; Zhou, Xiaochen; Kneale, Geoff; Mikol, Jacqueline; Lehmann, Sylvain; Surewicz, Witold K; Castilla, Joaquín; Steyaert, Jan; Zhang, Shulin; Kong, Qingzhong; Petersen, Robert B; Wohlkonig, Alexandre; Zou, Wen-Quan

2013-10-09

Prion diseases are associated with the conformational conversion of the cellular prion protein (PrP(C)) into the pathological scrapie isoform (PrP(Sc)) in the brain. Both the in vivo and in vitro conversion of PrP(C) into PrP(Sc) is significantly inhibited by differences in amino acid sequence between the two molecules. Using protein misfolding cyclic amplification (PMCA), we now report that the recombinant full-length human PrP (rHuPrP23-231) (that is unglycosylated and lacks the glycophosphatidylinositol anchor) is a strong inhibitor of human prion propagation. Furthermore, rHuPrP23-231 also inhibits mouse prion propagation in a scrapie-infected mouse cell line. Notably, it binds to PrP(Sc), but not PrP(C), suggesting that the inhibitory effect of recombinant PrP results from blocking the interaction of brain PrP(C) with PrP(Sc). Our findings suggest a new avenue for treating prion diseases, in which a patient's own unglycosylated and anchorless PrP is used to inhibit PrP(Sc) propagation without inducing immune response side effects.

Increased expression of p62/SQSTM1 in prion diseases and its association with pathogenic prion protein.

Science.gov (United States)

Homma, Takujiro; Ishibashi, Daisuke; Nakagaki, Takehiro; Satoh, Katsuya; Sano, Kazunori; Atarashi, Ryuichiro; Nishida, Noriyuki

2014-03-28

Prion diseases are neurodegenerative disorders characterized by the aggregation of abnormally folded prion protein (PrP(Sc)). In this study, we focused on the mechanism of clearance of PrP(Sc), which remains unclear. p62 is a cytosolic protein known to mediate both the formation and degradation of aggregates of abnormal proteins. The levels of p62 protein increased in prion-infected brains and persistently infected cell cultures. Upon proteasome inhibition, p62 co-localized with PrP(Sc), forming a large aggregate in the perinuclear region, hereafter referred to as PrP(Sc)-aggresome. These aggregates were surrounded with autophagosome marker LC3 and lysosomes in prion-infected cells. Moreover, transient expression of the phosphomimic form of p62, which has enhanced ubiquitin-binding activity, reduced the amount of PrP(Sc) in prion-infected cells, indicating that the activation of p62 could accelerate the clearance of PrP(Sc). Our findings would thus suggest that p62 could be a target for the therapeutic control of prion diseases.

Structure of organometallic compounds obtained by plasma of titanium isopropoxide

International Nuclear Information System (INIS)

Arreola R, M. L.

2012-01-01

This work presents a study on the synthesis and characterization of organometallic compounds of titanium oxide obtained from glow discharges of titanium tetraisopropoxide (TTIP) and water on glass and polyethylene. The objective is the synthesis of titanium oxide particles which can be fixed on different supports for use in further studies of contaminants degradation in effluent streams. The synthesis was carried out by plasma in a glass tubular reactor of 750 cm 3 and 15 cm length at 10 -1 mbar with power between 100 and 150 W during 2, 3 and 4 h. The precursors were TTIP and water vapor. TTIP is an organometallic compound composed of a central atom of Ti surrounded by 4 O atoms, which in turn are connected with chains of 3 C (propane s). The objective is the use of plasma collisions to separate the organic and inorganic phases of TTIP, so that both structure independently in a single material. The result was the formation of white titanium oxide powder composed with agglomerates of spherical particles with average diameter between 160 and 452 nm adhered to small films. The agglomerates have a tendency to change from film to particles with the energy applied to the synthesis. The study of the chemical structure showed a great presence of O 2 -Ti-O 2 (Ti surrounded by O) which can be found in most titanium oxides. Other chemical groups belonging to the organic phase were C=C=C, C=C=O and C 2 -C-Ch appearing from the dehydrogenation of TTIP, which can be a possible precursor of this reactions kind. The structural superficial analyses showed that the atomic composition varies according to type of substrate used. The greatest content of Ti was obtained on glass substrates. However, the synthesis conditions had not evident effect in the participation of chemical states found in the inorganic phase. The crystalline studies indicated that the material is amorphous, although the de convoluted X-ray spectra showed that the synthesized titanium oxides on glass tend to

Electronic structure of beta-FeSi sub 2 obtained by maximum entropy method and photoemission spectroscopy

CERN Document Server

Kakemoto, H; Makita, Y; Kino, Y; Tsukamoto, T; Shin, S; Wada, S; Tsurumi, T

2003-01-01

The electronic structure of beta-FeSi sub 2 was investigated by maximum entropy method (MEM) and photoemission spectroscopy. The electronic structure obtained by MEM using X-ray diffraction data at room temperature (RT) showed covalent bonds of Fe-Si and Si-Si electrons. The photoemission spectra of beta-FeSi sub 2 at RT were changed by incidence photon energies. For photon energies between 50 and 100 eV, resonant photoemission spectra caused by a super Coster-Kronig transition were observed. In order to reduce resonant effect about Fe(3d) for obtained photoemission spectra, difference spectrum between 53 and 57 eV was calculated, and it was compared with ab-initio band calculation and spectra function.

Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

Energy Technology Data Exchange (ETDEWEB)

Klimenov, V. A., E-mail: klimenov@tpu.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Kurgan, K. A., E-mail: kirill-k2.777@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Chumaevskii, A. V., E-mail: tch7av@gmail.com [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, 2/4 Akademicheskii pr., Tomsk, 634021 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Gnyusov, S. F., E-mail: gnusov@rambler.ru [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation)

2016-01-15

The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

Managing structural design through integrated models and obtaining increased safety and economy

International Nuclear Information System (INIS)

Diaz, B.E.; Thomaz, E.C.S.

1987-01-01

The use of large finite element (FE) models for the design of reinforced concrete elements in nuclear power plants will be treated. For this technique a set of computer programs is necessary, since the amount of data is very large. With this design method a series of advantages is obtained such as: reduction of reinforcing steel expenditure, increase of safety through a better representation of the structures, an adequate control of the calculation due to the transparent method of design, reduction of design time due to the automatic computation and so on. (author)

Structure characterization of nanocrystalline Ni–W alloys obtained by electrodeposition

Energy Technology Data Exchange (ETDEWEB)

Indyka, P., E-mail: paulina.indyka@uj.edu.pl [Jagiellonian University, Faculty of Chemistry, 3 Ingardena St., 30-059 Krakow (Poland); Beltowska-Lehman, E.; Tarkowski, L.; Bigos, A. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta St., 30-059 Krakow (Poland); García-Lecina, E. [Surface Finishing Department, CIDETEC-IK4 – Centre for Electrochemical Technologies, P° Miramón 196, 20009 Donostia-San Sebastián (Spain)

2014-03-25

Highlights: • Ni–W alloy coatings were electrodeposited from an aqueous electrolyte solutions. • The microstructure was studied with respect to electrodeposition process parameters. • We report optimal plating conditions for crack-free, nanocrystalline Ni–W coatings. • Crystalline Ni–W coatings exhibited the phase structure of an α-Ni(W) solid solution. • Coatings revealed tensile residual stresses and weakly pronounced 〈1 1 0〉 fiber texture. -- Abstract: Ni–W coatings of different tungsten content (2–50 wt%) were electrodeposited on a steel substrates from an aqueous complex sulfate–citrate galvanic baths, under controlled hydrodynamic conditions in a Rotating Disk Electrode (RDE) system. The optimum conditions for the electrodeposition of crack-free, homogeneous nanocrystalline Ni–W coatings were determined on the basis of the microstructure investigation results. The XRD structural characterizations of Ni–W alloy coatings obtained under different experimental conditions were complemented by SEM and TEM analysis. Results of the study revealed that the main factor influencing the microstructure formation of the Ni–W coatings is the chemical composition of an electrolyte solution. X-ray and electron diffraction patterns of all nanocrystalline Ni–W coatings revealed mainly the fcc phase structure of an α-Ni(W) solid solution with a lattice parameter increased along with tungsten content. The use of additives in the plating bath resulted in the formation of equiaxial/quasifibrous, nanocrystalline Ni–W grains of an average size of about 10 nm. The coatings were characterized by relatively high tensile residual stresses (500–1000 MPa), depending on the electrodeposition conditions. Ni–W coatings exhibited weakly pronounced fiber type 〈1 1 0〉 crystallographic texture, consistent with the symmetry of the plating process. Coatings of the highest tungsten content 50 wt% were found to be amorphous.

Discovery of a novel, monocationic, small-molecule inhibitor of scrapie prion accumulation in cultured sheep microglia and Rov cells.

Directory of Open Access Journals (Sweden)

James B Stanton

Full Text Available Prion diseases, including sheep scrapie, are neurodegenerative diseases with the fundamental pathogenesis involving conversion of normal cellular prion protein (PrP(C to disease-associated prion protein (PrP(Sc. Chemical inhibition of prion accumulation is widely investigated, often using rodent-adapted prion cell culture models. Using a PrP(Sc-specific ELISA we discovered a monocationic phenyl-furan-benzimidazole (DB772, which has previously demonstrated anti-pestiviral activity and represents a chemical category previously untested for anti-prion activity, that inhibited PrP(Sc accumulation and prion infectivity in primary sheep microglial cell cultures (PRNP 136VV/154RR/171QQ and Rov9 cultures (VRQ-ovinized RK13 cells. We investigated potential mechanisms of this anti-prion activity by evaluating PrP(C expression with quantitative RT-PCR and PrP ELISA, comparing the concentration-dependent anti-prion and anti-pestiviral effects of DB772, and determining the selectivity index. Results demonstrate at least an approximate two-log inhibition of PrP(Sc accumulation in the two cell systems and confirmed that the inhibition of PrP(Sc accumulation correlates with inhibition of prion infectivity. PRNP transcripts and total PrP protein concentrations within cell lysates were not decreased; thus, decreased PrP(C expression is not the mechanism of PrP(Sc inhibition. PrP(Sc accumulation was multiple logs more resistant than pestivirus to DB772, suggesting that the anti-PrP(Sc activity was independent of anti-pestivirus activity. The anti-PrP(Sc selectivity index in cell culture was approximately 4.6 in microglia and 5.5 in Rov9 cells. The results describe a new chemical category that inhibits ovine PrP(Sc accumulation in primary sheep microglia and Rov9 cells, and can be used for future studies into the treatment and mechanism of prion diseases.

Protease-resistant prions selectively decrease Shadoo protein.

Directory of Open Access Journals (Sweden)

Joel C Watts

2011-11-01

Full Text Available The central event in prion diseases is the conformational conversion of the cellular prion protein (PrP(C into PrP(Sc, a partially protease-resistant and infectious conformer. However, the mechanism by which PrP(Sc causes neuronal dysfunction remains poorly understood. Levels of Shadoo (Sho, a protein that resembles the flexibly disordered N-terminal domain of PrP(C, were found to be reduced in the brains of mice infected with the RML strain of prions [1], implying that Sho levels may reflect the presence of PrP(Sc in the brain. To test this hypothesis, we examined levels of Sho during prion infection using a variety of experimental systems. Sho protein levels were decreased in the brains of mice, hamsters, voles, and sheep infected with different natural and experimental prion strains. Furthermore, Sho levels were decreased in the brains of prion-infected, transgenic mice overexpressing Sho and in infected neuroblastoma cells. Time-course experiments revealed that Sho levels were inversely proportional to levels of protease-resistant PrP(Sc. Membrane anchoring and the N-terminal domain of PrP both influenced the inverse relationship between Sho and PrP(Sc. Although increased Sho levels had no discernible effect on prion replication in mice, we conclude that Sho is the first non-PrP marker specific for prion disease. Additional studies using this paradigm may provide insight into the cellular pathways and systems subverted by PrP(Sc during prion disease.

Lack of prion accumulation in lymphoid tissues of PRNP ARQ/ARR sheep intracranially inoculated with the agent of scrapie.

Science.gov (United States)

Greenlee, Justin J; Kunkle, Robert A; Richt, Jürgen A; Nicholson, Eric M; Hamir, Amir N

2014-01-01

Sheep scrapie is a transmissible spongiform encephalopathy that can be transmitted horizontally. The prion protein gene (PRNP) profoundly influences the susceptibility of sheep to the scrapie agent and the tissue levels and distribution of PrPSc in affected sheep. The purpose of this study was to compare the survival time and PrPSc tissue distribution in sheep with highly resistant and highly susceptible PRNP genotypes after intracranial inoculation of the agent of scrapie. Five sheep each of genotype VRQ/VRQ, VRQ/ARR or ARQ/ARR were inoculated. Sheep were euthanized when clinical signs of scrapie became severe. Clinical signs, microscopic lesions, and western blot profiles were uniform across genotypes and consistent with manifestations of classical scrapie. Mean survival time differences were associated with the 171 polymorphic site with VRQ/VRQ sheep surviving 18 months, whereas VRQ/ARR and ARQ/ARR sheep survived 60 and 56 months, respectively. Labeling of PrPSc by immunohistochemistry revealed similar accumulations in central nervous system tissues regardless of host genotype. Immunoreactivity for PrPSc in lymphoid tissue was consistently abundant in VRQ/VRQ, present but confined to tonsil or retropharyngeal lymph node in 4/5 VRQ/ARR, and totally absent in ARQ/ARR sheep. The results of this study demonstrate the susceptibility of sheep with the ARQ/ARR genotype to scrapie by the intracranial inoculation route with PrPSc accumulation in CNS tissues, but prolonged incubation times and lack of PrPSc in lymphoid tissue.

Structural analysis and magnetic properties of solid solutions of Co–Cr system obtained by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Betancourt-Cantera, J.A. [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Sánchez-De Jesús, F., E-mail: fsanchez@uaeh.edu.mx [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Bolarín-Miró, A.M. [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Betancourt, I.; Torres-Villaseñor, G. [Departamento de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico)

2014-03-15

In this paper, a systematic study on the structural and magnetic properties of Co{sub 100−x}Cr{sub x} alloys (0obtained by mechanical alloying is presented. Co and Cr elemental powders were used as precursors, and mixed in an adequate weight ratio to obtain Co{sub 1−x}Cr{sub x} (0structures were obtained. The saturation polarization indicated a maximum value of 1.17 T (144 Am{sup 2}/kg) for the Co{sub 90}Cr{sub 10}, which decreases with the increasing of the Cr content up to x=80, as a consequence of the dilution effect of the magnetic moment which is caused by the Cr content and by the competition between ferromagnetic and antiferromagnetic exchange interactions. The coercivity increases up to 34 kA/m (435 Oe) for Co{sub 40}Cr{sub 60}. For Cr rich compositions, it is observed an important decrease reaching 21 kA/m (272 Oe) for Co{sub 10}Cr{sub 90,} it is related to the grain size and the structural change. Besides, the magnetic anisotropy constant was determined for each composition. Magnetic thermogravimetric analysis allowed to obtain Curie temperatures corresponding to the formation of hcp-Co(Cr) and fcc-Co(Cr) solid solutions. - Highlights: • Mechanical alloying (MA) induces the formation of solid solutions of Co–Cr system in non-equilibrium. • We report the crystal structure and the magnetic behavior of Co–Cr alloys produced by MA. • MA improves the magnetic properties of Co–Cr system.

Structure investigations of ferromagnetic Co-Ni-Al alloys obtained by powder metallurgy.

Science.gov (United States)

Maziarz, W; Dutkiewicz, J; Lityńska-Dobrzyńska, L; Santamarta, R; Cesari, E

2010-03-01

Elemental powders of Co, Ni and Al in the proper amounts to obtain Co(35)Ni(40)Al(25) and Co(40)Ni(35)Al(25) nominal compositions were ball milled in a high-energy mill for 80 h. After 40 h of milling, the formation of a Co (Ni, Al) solid solution with f.c.c. structure was verified by a change of the original lattice parameter and crystallite size. Analytical transmission electron microscopy observations and X-ray diffraction measurements of the final Co (Ni, Al) solid solution showed that the crystallite size scattered from 4 to 8 nm and lattice parameter a = 0.36086 nm. The chemical EDS point analysis of the milled powder particles allowed the calculation of the e/a ratio and revealed a high degree of chemical homogeneity of the powders. Hot pressing in vacuum of the milled powders resulted in obtaining compacts with a density of about 70% of the theoretical one. An additional heat treatment increased the density and induced the martensitic transformation in a parent phase. Selected area diffraction patterns and dark field images obtained from the heat-treated sample revealed small grains around 300 nm in diameter consisting mainly of the ordered gamma phase (gamma'), often appearing as twins, and a small amount of the L1(0) ordered martensite.

Pathogenesis of bovine spongiform encephalopathy in sheep

NARCIS (Netherlands)

Keulen, van L.J.M.; Vromans, M.E.W.; Dolstra, C.H.; Bossers, A.; Zijderveld, van F.G.

2008-01-01

The pathogenesis of bovine spongiform encephalopathy (BSE) in sheep was studied by immunohistochemical detection of scrapie-associated prion protein (PrPSc) in the gastrointestinal, lymphoid and neural tissues following oral inoculation with BSE brain homogenate. First accumulation of PrPSc was

Structural and magnetic properties of FeCoC system obtained by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Rincón Soler, A. I. [Universidad Tecnológica de Pereira, Fac. de Ciencias, Depto. de Física (Colombia); Rodríguez Jacobo, R. R., E-mail: rrrodriguez@uao.edu.co [Universidad Autónoma de Occidente, Fac. de Ciencias Básicas, Depto. de Física (Colombia); Medina Barreto, M. H.; Cruz-Muñoz, B. [Universidad Tecnológica de Pereira, Fac. de Ciencias, Depto. de Física (Colombia)

2017-11-15

Fe{sub 96−X}Co{sub X}C{sub 4} (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

Structural and magnetic properties of FeCoC system obtained by mechanical alloying

International Nuclear Information System (INIS)

Rincón Soler, A. I.; Rodríguez Jacobo, R. R.; Medina Barreto, M. H.; Cruz-Muñoz, B.

2017-01-01

Fe 96−X Co X C 4 (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

3D local structure around copper site of rabbit prion-related protein: Quantitative determination by XANES spectroscopy combined with multiple-scattering calculations

Science.gov (United States)

Cui, P. X.; Lian, F. L.; Wang, Y.; Wen, Yi; Chu, W. S.; Zhao, H. F.; Zhang, S.; Li, J.; Lin, D. H.; Wu, Z. Y.

2014-02-01

Prion-related protein (PrP), a cell-surface copper-binding glycoprotein, is considered to be responsible for a number of transmissible spongiform encephalopathies (TSEs). The structural conversion of PrP from the normal cellular isoform (PrPC) to the post-translationally modified form (PrPSc) is thought to be relevant to Cu2+ binding to histidine residues. Rabbits are one of the few mammalian species that appear to be resistant to TSEs, because of the structural characteristics of the rabbit prion protein (RaPrPC) itself. Here we determined the three-dimensional local structure around the C-terminal high-affinity copper-binding sites using X-ray absorption near-edge structure combined with ab initio calculations in the framework of the multiple-scattering (MS) theory. Result shows that two amino acid resides, Gln97 and Met108, and two histidine residues, His95 and His110, are involved in binding this copper(II) ion. It might help us understand the roles of copper in prion conformation conversions, and the molecular mechanisms of prion-involved diseases.

Mammalian prions

Science.gov (United States)

Salamat, Muhammad Khalid; Munoz-Montesino, Carola; Moudjou, Mohammed; Rezaei, Human; Laude, Hubert; Béringue, Vincent; Dron, Michel

2013-01-01

Upon prion infection, abnormal prion protein (PrPSc) self-perpetuate by conformational conversion of α-helix-rich PrPC into β sheet enriched form, leading to formation and deposition of PrPSc aggregates in affected brains. However the process remains poorly understood at the molecular level and the regions of PrP critical for conversion are still debated. Minimal amino acid substitutions can impair prion replication at many places in PrP. Conversely, we recently showed that bona fide prions could be generated after introduction of eight and up to 16 additional amino acids in the H2-H3 inter-helix loop of PrP. Prion replication also accommodated the insertions of an octapeptide at different places in the last turns of H2. This reverse genetic approach reveals an unexpected tolerance of prions to substantial sequence changes in the protease-resistant part which is associated with infectivity. It also demonstrates that conversion does not require the presence of a specific sequence in the middle of the H2-H3 area. We discuss the implications of our findings according to different structural models proposed for PrPSc and questioned the postulated existence of an N- or C-terminal prion domain in the protease-resistant region. PMID:23232499

Electronic and magnetic structure of BaCoO2 as obtained from LSDA and LSDA+U calculations

KAUST Repository

Nazir, Safdar

2011-03-01

Density functional theory is used to study the structural, electronic, and magnetic properties of BaCoO2. Structural relaxation for different collinear magnetic configurations points to a remarkable magneto-elastic coupling in BaCoO2. Although we obtain several stable long range ordered magnetic structures, ferromagnetism is energetically favorable in the case of the LSDA method. In contrast, for the LSDA+U method antiferromagnetic ordering is found to be favorable. © 2011 Elsevier B.V. All rights reserved.

Quantifying the relative amounts of PrP polymorphisms present in prions isolated from heterozygous prion-infected animals

Science.gov (United States)

Prions cause protein misfolding diseases, such as transmissible spongiform encephalopathy. They propagate infections by converting a normal cellular prion protein into a prion (PrPSc). PrPC and PrPSc are isosequential and differ only in their respective conformations. PrPC is monomeric and sensit...

Critical significance of the region between Helix 1 and 2 for efficient dominant-negative inhibition by conversion-incompetent prion protein.

Directory of Open Access Journals (Sweden)

Yuzuru Taguchi

Full Text Available Prion diseases are fatal infectious neurodegenerative disorders in man and animals associated with the accumulation of the pathogenic isoform PrP(Sc of the host-encoded prion protein (PrP(c. A profound conformational change of PrP(c underlies formation of PrP(Sc and prion propagation involves conversion of PrP(c substrate by direct interaction with PrP(Sc template. Identifying the interfaces and modalities of inter-molecular interactions of PrPs will highly advance our understanding of prion propagation in particular and of prion-like mechanisms in general. To identify the region critical for inter-molecular interactions of PrP, we exploited here dominant-negative inhibition (DNI effects of conversion-incompetent, internally-deleted PrP (ΔPrP on co-expressed conversion-competent PrP. We created a series of ΔPrPs with different lengths of deletions in the region between first and second α-helix (H1∼H2 which was recently postulated to be of importance in prion species barrier and PrP fibril formation. As previously reported, ΔPrPs uniformly exhibited aberrant properties including detergent insolubility, limited protease digestion resistance, high-mannose type N-linked glycans, and intracellular localization. Although formerly controversial, we demonstrate here that ΔPrPs have a GPI anchor attached. Surprisingly, despite very similar biochemical and cell-biological properties, DNI efficiencies of ΔPrPs varied significantly, dependant on location and inversely correlated with the size of deletion. This data demonstrates that H1∼H2 and the region C-terminal to it are critically important for efficient DNI. It also suggests that this region is involved in PrP-PrP interaction and conversion of PrP(C into PrP(Sc. To reconcile the paradox of how an intracellular PrP can exert DNI, we demonstrate that ΔPrPs are subject to both proteasomal and lysosomal/autophagic degradation pathways. Using autophagy pathways ΔPrPs obtain access to the locale

Predicting welding distortion in a panel structure with longitudinal stiffeners using inherent deformations obtained by inverse analysis method.

Science.gov (United States)

Liang, Wei; Murakawa, Hidekazu

2014-01-01

Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results.

Preclinical deposition of pathological prion protein in muscle of experimentally infected primates.

Directory of Open Access Journals (Sweden)

Susanne Krasemann

Full Text Available Prion diseases are transmissible fatal neurodegenerative disorders affecting humans and animals. A central step in disease progression is the accumulation of a misfolded form (PrP(Sc of the host encoded prion protein (PrP(C in neuronal and non-neuronal tissues. The involvement of peripheral tissues in preclinical states increases the risk of accidental transmission. On the other hand, detection of PrP(Sc in non-neuronal easy-accessible compartments such as muscle may offer a novel diagnostic tool. Primate models have proven invaluable to investigate prion diseases. We have studied the deposition of PrP(Sc in muscle and central nervous system of rhesus monkeys challenged with sporadic Creutzfeldt-Jakob disease (sCJD, variant CJD (vCJD and bovine spongiform encephalopathy (BSE in preclinical and clinical stage using biochemical and morphological methods. Here, we show the preclinical presence of PrP(Sc in muscle and central nervous system of rhesus monkeys experimentally infected with vCJD.

Process of obtaining the multilayer structure

International Nuclear Information System (INIS)

Buzdugan, A.; Dolghieru, V.; Jitari, V.; Colomeico, E.; Popescu, A.

1997-01-01

The invention relates to the multilayer structures of glassy semiconductors with the refractive index abrupt and smooth variation at the bound between the layers and may be used for manufacturing the optical information transmission and recording media. With a view to simplify the technology, compositionally different layers of chalcogenide glassy semiconductors having various refractive indexes from As 2 S 3 , are being by thermal vacuum evaporation, changing the vaporization temperature thereof from 120 to 280 C

Glycoform-selective prion formation in sporadic and familial forms of prion disease

NARCIS (Netherlands)

Xiao, X.; Yuan, J.; Haïk, S.; Cali, I.; Zhan, Y.; Moudjou, M.; Li, B.; Laplanche, J.L.; Laude, H.; Langeveld, J.P.M.; Gambetti, P.

2013-01-01

The four glycoforms of the cellular prion protein (PrP(C)) variably glycosylated at the two N-linked glycosylation sites are converted into their pathological forms (PrP(Sc)) in most cases of sporadic prion diseases. However, a prominent molecular characteristic of PrP(Sc) in the recently identified

LIGNIN, STRUCTURE AND APPLICATIONS: DEPOLYMERIZATION METHODS FOR OBTAINING AROMATIC DERIVATIVES OF INDUSTRIAL INTEREST

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Marvin Chávez-Sifontes

2013-12-01

Full Text Available In this article significant data related to the structural characteristics of lignin, the extraction and isolation processes from biomass, and also the characteristics of different types of commercial lignins are presented. The review focuses on the different depolymerization processes (hydrolysis, hydrogenolysis, hydrodeoxygenation, pyrolysis, among others up to now developed and investigated analyzing the different aromatic derivatives obtained in each case, as well as the interesting reactions some of them may undergo. Application possibilities for lignin and its derivatives in new industrial processes integrated into the bio-refinery of the future are finally assessed

Endogenous proteolytic cleavage of disease-associated prion protein to produce C2 fragments is strongly cell- and tissue-dependent.

Science.gov (United States)

Dron, Michel; Moudjou, Mohammed; Chapuis, Jérôme; Salamat, Muhammad Khalid Farooq; Bernard, Julie; Cronier, Sabrina; Langevin, Christelle; Laude, Hubert

2010-04-02

The abnormally folded form of the prion protein (PrP(Sc)) accumulating in nervous and lymphoid tissues of prion-infected individuals can be naturally cleaved to generate a N-terminal-truncated fragment called C2. Information about the identity of the cellular proteases involved in this process and its possible role in prion biology has remained limited and controversial. We investigated PrP(Sc) N-terminal trimming in different cell lines and primary cultured nerve cells, and in the brain and spleen tissue from transgenic mice infected by ovine and mouse prions. We found the following: (i) the full-length to C2 ratio varies considerably depending on the infected cell or tissue. Thus, in primary neurons and brain tissue, PrP(Sc) accumulated predominantly as untrimmed species, whereas efficient trimming occurred in Rov and MovS cells, and in spleen tissue. (ii) Although C2 is generally considered to be the counterpart of the PrP(Sc) proteinase K-resistant core, the N termini of the fragments cleaved in vivo and in vitro can actually differ, as evidenced by a different reactivity toward the Pc248 anti-octarepeat antibody. (iii) In lysosome-impaired cells, the ratio of full-length versus C2 species dramatically increased, yet efficient prion propagation could occur. Moreover, cathepsin but not calpain inhibitors markedly inhibited C2 formation, and in vitro cleavage by cathepsins B and L produced PrP(Sc) fragments lacking the Pc248 epitope, strongly arguing for the primary involvement of acidic hydrolases of the endolysosomal compartment. These findings have implications on the molecular analysis of PrP(Sc) and cell pathogenesis of prion infection.

Endogenous Proteolytic Cleavage of Disease-associated Prion Protein to Produce C2 Fragments Is Strongly Cell- and Tissue-dependent*

Science.gov (United States)

Dron, Michel; Moudjou, Mohammed; Chapuis, Jérôme; Salamat, Muhammad Khalid Farooq; Bernard, Julie; Cronier, Sabrina; Langevin, Christelle; Laude, Hubert

2010-01-01

The abnormally folded form of the prion protein (PrPSc) accumulating in nervous and lymphoid tissues of prion-infected individuals can be naturally cleaved to generate a N-terminal-truncated fragment called C2. Information about the identity of the cellular proteases involved in this process and its possible role in prion biology has remained limited and controversial. We investigated PrPSc N-terminal trimming in different cell lines and primary cultured nerve cells, and in the brain and spleen tissue from transgenic mice infected by ovine and mouse prions. We found the following: (i) the full-length to C2 ratio varies considerably depending on the infected cell or tissue. Thus, in primary neurons and brain tissue, PrPSc accumulated predominantly as untrimmed species, whereas efficient trimming occurred in Rov and MovS cells, and in spleen tissue. (ii) Although C2 is generally considered to be the counterpart of the PrPSc proteinase K-resistant core, the N termini of the fragments cleaved in vivo and in vitro can actually differ, as evidenced by a different reactivity toward the Pc248 anti-octarepeat antibody. (iii) In lysosome-impaired cells, the ratio of full-length versus C2 species dramatically increased, yet efficient prion propagation could occur. Moreover, cathepsin but not calpain inhibitors markedly inhibited C2 formation, and in vitro cleavage by cathepsins B and L produced PrPSc fragments lacking the Pc248 epitope, strongly arguing for the primary involvement of acidic hydrolases of the endolysosomal compartment. These findings have implications on the molecular analysis of PrPSc and cell pathogenesis of prion infection. PMID:20154089

Assessment of national systems for obtaining local siting acceptance of nuclear waste management facilities (October 1, 1985). Volume I. Political structure and formal system for obtaining approvals for siting waste management facilities

International Nuclear Information System (INIS)

Paige, H.W.; Numark, N.J.

1985-01-01

This report is the fourth in a series of periodic surveys of approaches and progress in other countries in dealing with the problems of obtaining local acceptance for siting of waste management facilities. This volume contains the following sections: Nation's political/industrial structure for obtaining waste management siting decisions; and Nation's formal legal procedure for obtaining necessary approvals for siting nuclear waste management facilities. Two of the countries visited, Finland and Sweden, have had major changes in the past two years in their formal/legal procedures for obtaining waste management siting decisions. (LM)

Structural characterization of HDPE/LLDPE blend-based nano composites obtained by different blending sequence

International Nuclear Information System (INIS)

Passador, Fabio R.; Ruvolo Filho, Adhemar; Pessan, Luiz A.

2011-01-01

The blending sequence affects the morphology formation of the nanocomposites. In this work, the blending sequences were explored to determine its influence in the rheological behavior of HDPE/LLDPE/OMMT nanocomposites. The nanocomposites were obtained by melt-intercalation using a mixture of LLDPE-g-MA and HDPE-g-MA as compatibilizer system in a torque rheometer at 180 deg C and five blending sequences were studied. The materials structures were characterized by wide angle X-ray diffraction (WAXD) and by rheological properties. The nanoclay's addition increased the shear viscosity at low shear rates, changing the behavior of HDPE/LLDPE matrix to a Bingham model behavior with an apparent yield stress. Intense interactions were obtained for the blending sequence where LLDPE and/or LLDPE-g-MA were first reinforced with organoclay since the intercalation process occurs preferentially in the amorphous phase. (author)

Probing Early Misfolding Events in Prion Protein Mutants by NMR Spectroscopy

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Gregor Ilc

2013-08-01

Full Text Available The post-translational conversion of the ubiquitously expressed cellular form of the prion protein, PrPC, into its misfolded and pathogenic isoform, known as prion or PrPSc, plays a key role in prion diseases. These maladies are denoted transmissible spongiform encephalopathies (TSEs and affect both humans and animals. A prerequisite for understanding TSEs is unraveling the molecular mechanism leading to the conversion process whereby most α-helical motifs are replaced by β-sheet secondary structures. Importantly, most point mutations linked to inherited prion diseases are clustered in the C-terminal domain region of PrPC and cause spontaneous conversion to PrPSc. Structural studies with PrP variants promise new clues regarding the proposed conversion mechanism and may help identify “hot spots” in PrPC involved in the pathogenic conversion. These investigations may also shed light on the early structural rearrangements occurring in some PrPC epitopes thought to be involved in modulating prion susceptibility. Here we present a detailed overview of our solution-state NMR studies on human prion protein carrying different pathological point mutations and the implications that such findings may have for the future of prion research.

Experimental approaches to the interaction of the prion protein with nucleic acids and glycosaminoglycans: Modulators of the pathogenic conversion.

Science.gov (United States)

Silva, Jerson L; Vieira, Tuane C R G; Gomes, Mariana P B; Rangel, Luciana P; Scapin, Sandra M N; Cordeiro, Yraima

2011-03-01

The concept that transmissible spongiform encephalopathies (TSEs) are caused only by proteins has changed the traditional paradigm that disease transmission is due solely to an agent that carries genetic information. The central hypothesis for prion diseases proposes that the conversion of a cellular prion protein (PrP(C)) into a misfolded, β-sheet-rich isoform (PrP(Sc)) accounts for the development of (TSE). There is substantial evidence that the infectious material consists chiefly of a protein, PrP(Sc), with no genomic coding material, unlike a virus particle, which has both. However, prions seem to have other partners that chaperone their activities in converting the PrP(C) into the disease-causing isoform. Nucleic acids (NAs) and glycosaminoglycans (GAGs) are the most probable accomplices of prion conversion. Here, we review the recent experimental approaches that have been employed to characterize the interaction of prion proteins with nucleic acids and glycosaminoglycans. A PrP recognizes many nucleic acids and GAGs with high affinities, and this seems to be related to a pathophysiological role for this interaction. A PrP binds nucleic acids and GAGs with structural selectivity, and some PrP:NA complexes can become proteinase K-resistant, undergoing amyloid oligomerization and conversion to a β-sheet-rich structure. These results are consistent with the hypothesis that endogenous polyanions (such as NAs and GAGs) may accelerate the rate of prion disease progression by acting as scaffolds or lattices that mediate the interaction between PrP(C) and PrP(Sc) molecules. In addition to a still-possible hypothesis that nucleic acids and GAGs, especially those from the host, may modulate the conversion, the recent structural characterization of the complexes has raised the possibility of developing new diagnostic and therapeutic strategies. Copyright © 2010 Elsevier Inc. All rights reserved.

Detection of type 1 prion protein in variant Creutzfeldt-Jakob disease

NARCIS (Netherlands)

Yull, H.M.; Ritchie, D.L.; Langeveld, J.P.M.; Zijderveld, van F.G.; Bruce, M.E.; Ironside, J.W.; Head, M.W.

2006-01-01

Molecular typing of the abnormal form of the prion protein (PrPSc) has come to be regarded as a powerful tool in the investigation of the prion diseases. All evidence thus far presented indicates a single PrPSc molecular type in variant Creutzfeldt-Jakob disease (termed type 2B), presumably

Semi-purification procedures of prions from a prion-infected brain using sucrose has no influence on the nonenzymatic glycation of the disease-associated prion isoform.

Science.gov (United States)

Choi, Yeong-Gon; Kim, Jae-Il; Choi, Eun-Kyoung; Carp, Richard I; Kim, Yong-Sun

2016-01-01

Previous studies have shown that the Nε-carboxymethyl group is linked to not only one or more N-terminal Lys residues but also to one or more Lys residues of the protease-resistant core region of the pathogenic prion isoform (PrPSc) in prion-infected brains. Using an anti-advanced glycation end product (AGE) antibody, we detected nonenzymatically glycated PrPSc (AGE-PrPSc) in prion-infected brains following concentration by a series of ultracentrifugation steps with a sucrose cushion. In the present study, the levels of in vitro nonenzymatic glycation of PrPSc using sucrose were investigated to determine whether sucrose cushion can artificially and nonenzymatically induce in vitro glycation during ultracentrifugation. The first insoluble pellet fraction following the first ultracentrifugation (PU1st) collected from 263K scrapie-infected brains was incubated with sucrose, glucose or colloidal silica coated with polyvinylpyrrolidone (percoll). None of the compounds in vitro resulted in AGE-PrPSc. Nonetheless, glucose and percoll produced AGEs in vitro from other proteins within PU1st of the infected brains. This reaction could lead to the AGE-modified polymer(s) of nonenzymatic glycation-prone protein(s). This study showed that PrPSc is not nonenzymatically glycated in vitro with sucrose, glucose or percoll and that AGE-modified PrPSc can be isolated and enriched from prion-infected brains.

Effect of substrate bias on structure and properties of the TiN coatings obtained in the PVD process

International Nuclear Information System (INIS)

Dobrzanski, L.A.; Kwasny, W.

2003-01-01

The paper presents investigation results of the field of deposition parameters on structure and mechanical properties of the TiN coatings obtained by magnetron sputtering in the vacuum furnace onto the ASP 30 sintered high speed steel. Effect of sputtering parameters on chemical and phase composition, thickness, microhardness and roughness parameter. The characteristic structure and surface topography of the analyzed coatings are presented. (author)

Algorithm for repairing the damaged images of grain structures obtained from the cellular automata and measurement of grain size

Science.gov (United States)

Ramírez-López, A.; Romero-Romo, M. A.; Muñoz-Negron, D.; López-Ramírez, S.; Escarela-Pérez, R.; Duran-Valencia, C.

2012-10-01

Computational models are developed to create grain structures using mathematical algorithms based on the chaos theory such as cellular automaton, geometrical models, fractals, and stochastic methods. Because of the chaotic nature of grain structures, some of the most popular routines are based on the Monte Carlo method, statistical distributions, and random walk methods, which can be easily programmed and included in nested loops. Nevertheless, grain structures are not well defined as the results of computational errors and numerical inconsistencies on mathematical methods. Due to the finite definition of numbers or the numerical restrictions during the simulation of solidification, damaged images appear on the screen. These images must be repaired to obtain a good measurement of grain geometrical properties. Some mathematical algorithms were developed to repair, measure, and characterize grain structures obtained from cellular automata in the present work. An appropriate measurement of grain size and the corrected identification of interfaces and length are very important topics in materials science because they are the representation and validation of mathematical models with real samples. As a result, the developed algorithms are tested and proved to be appropriate and efficient to eliminate the errors and characterize the grain structures.

Optical and photoelectric properties of nanolamellar structures obtained by thermal annealing of InSe plates in Zn vapours

Energy Technology Data Exchange (ETDEWEB)

Untila, Dumitru; Evtodiev, Igor [Faculty of Physics and Engineering, Moldova State University, Chisinau (Moldova, Republic of); Ghitu Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Chisinau (Moldova, Republic of); Caraman, Iuliana [Engineering Department ' ' Vasile Alecsandri' ' , University of Bacau (Romania); Spalatu, Nicolae [Department of Materials Science, Tallinn University of Technology (Estonia); Dmitroglo, Liliana; Caraman, Mihail [Faculty of Physics and Engineering, Moldova State University, Chisinau (Moldova, Republic of)

2018-02-15

The structural, optical and photoelectric properties of InSe crystals grown by Bridgman-Stockbarger method and ZnSe/InSe structures obtained on InSe by thermal annealing in Zn vapours are studied in this paper. The study of structural properties confirms that ZnSe compound is formed. The analysis of photoelectric properties reveal that both the ZnSe-InSe composite layer and the composite/InSe heterojunction are photosensitive in the VIS-NIR spectral region. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Damage identification of beam structures using free response shapes obtained by use of a continuously scanning laser Doppler vibrometer system

Science.gov (United States)

Xu, Y. F.; Chen, Da-Ming; Zhu, W. D.

2017-08-01

Spatially dense operating deflection shapes and mode shapes can be rapidly obtained by use of a continuously scanning laser Doppler vibrometer (CSLDV) system, which sweeps its laser spot over a vibrating structure surface. This paper introduces a new type of vibration shapes called a free response shape (FRS) that can be obtained by use of a CSLDV system, and a new damage identification methodology using FRSs is developed for beam structures. An analytical expression of FRSs of a damped beam structure is derived, and FRSs from the analytical expression compare well with those from a finite element model. In the damage identification methodology, a free-response damage index (FRDI) is proposed, and damage regions can be identified near neighborhoods with consistently high values of FRDIs associated with different modes; an auxiliary FRDI is defined to assist identification of the neighborhoods. A FRDI associated with a mode consists of differences between curvatures of FRSs associated with the mode in a number of half-scan periods of a CSLDV system and those from polynomials that fit the FRSs with properly determined orders. A convergence index is proposed to determine the proper order of a polynomial fit. One advantage of the methodology is that the FRDI does not require any baseline information of an undamaged beam structure, if it is geometrically smooth and made of materials that have no stiffness and mass discontinuities. Another advantage is that FRDIs associated with multiple modes can be obtained using free response of a beam structure measured by a CSLDV system in one scan. The number of half-scan periods for calculation of the FRDI associated with a mode can be determined by use of the short-time Fourier transform. The proposed methodology was numerically and experimentally applied to identify damage in beam structures; effects of the scan frequency of a CSLDV system on qualities of obtained FRSs were experimentally investigated.

MM2-thalamic Creutzfeldt-Jakob disease: neuropathological, biochemical and transmission studies identify a distinctive prion strain.

Science.gov (United States)

Moda, Fabio; Suardi, Silvia; Di Fede, Giuseppe; Indaco, Antonio; Limido, Lucia; Vimercati, Chiara; Ruggerone, Margherita; Campagnani, Ilaria; Langeveld, Jan; Terruzzi, Alessandro; Brambilla, Antonio; Zerbi, Pietro; Fociani, Paolo; Bishop, Matthew T; Will, Robert G; Manson, Jean C; Giaccone, Giorgio; Tagliavini, Fabrizio

2012-09-01

In Creutzfeldt-Jakob disease (CJD), molecular typing based on the size of the protease resistant core of the disease-associated prion protein (PrP(Sc) ) and the M/V polymorphism at codon 129 of the PRNP gene correlates with the clinico-pathologic subtypes. Approximately 95% of the sporadic 129MM CJD patients are characterized by cerebral deposition of type 1 PrP(Sc) and correspond to the classic clinical CJD phenotype. The rare 129MM CJD patients with type 2 PrP(Sc) are further subdivided in a cortical and a thalamic form also indicated as sporadic fatal insomnia. We observed two young patients with MM2-thalamic CJD. Main neuropathological features were diffuse, synaptic PrP immunoreactivity in the cerebral cortex and severe neuronal loss and gliosis in the thalamus and olivary nucleus. Western blot analysis showed the presence of type 2A PrP(Sc) . Challenge of transgenic mice expressing 129MM human PrP showed that MM2-thalamic sporadic CJD (sCJD) was able to transmit the disease, at variance with MM2-cortical sCJD. The affected mice showed deposition of type 2A PrP(Sc) , a scenario that is unprecedented in this mouse line. These data indicate that MM2-thalamic sCJD is caused by a prion strain distinct from the other sCJD subtypes including the MM2-cortical form. © 2012 The Authors; Brain Pathology © 2012 International Society of Neuropathology.

The ionic structure of liquid sodium obtained by numerical simulation from 'first principles' and ab initio 'norm-conserving' pseudopotentials

International Nuclear Information System (INIS)

Harchaoui, N; Hellal, S; Grosdidier, B; Gasser, J G

2008-01-01

The physical properties of disordered matter depend on the 'atomic structure' i.e. the arrangement of the atoms. This arrangement is described by the structure factor S (q) in reciprocal space and by the pair correlation function g(r) in real space. The structure factor is obtained experimentally while the numerical simulation enables us to obtain the pair correlation function. Liquid sodium is one of the elements the most studied and one can wonder about new scientific contribution appropriateness. The majority of theoretical calculations are compared with the experiment of Waseda. However two other posterior measurements have been published and give different results, in particular with regard to the height of the first peak of the structure factor. Three models of pseudopotential are considered to describe the electron-ion interaction. The first is a local pseudopotential with the alternative known as 'individual' of the model suggested by Fiolhais et al. The second model considered is that of Bachelet et al. This one, ab-initio and 'norm conserving', is non local. The last model is that proposed by Shaw known as 'first principles' and 'energy dependent'. Various static dielectric functions characteristic of the effects of exchange and correlation have been used and developed by Hellal et al. We calculated the form factors (pseudopotential in reciprocal space) and deduce the normalized energy-wave-number characteristic F N (q), the interatomic pair potential V eff (r), then the pair correlation function g(r) by molecular dynamics. The structure factor S(q) is obtained by Fourier transform and is compared with the experiment. Our calculations with the Bachelet and Shaw pseudopotentials are close to the last experiments of Greenfield et al. and of Huijben et al. Our results are discussed

A novel class of potential prion drugs: preliminary in vitro and in vivo data for multilayer coated gold nanoparticles.

Science.gov (United States)

Ai Tran, Hoang Ngoc; Sousa, Fernanda; Moda, Fabio; Mandal, Subhra; Chanana, Munish; Vimercati, Chiara; Morbin, Michela; Krol, Silke; Tagliavini, Fabrizio; Legname, Giuseppe

2010-12-01

Gold nanoparticles coated with oppositely charged polyelectrolytes, such as polyallylamine hydrochloride and polystyrenesulfonate, were examined for potential inhibition of prion protein aggregation and prion (PrPSc) conversion and replication. Different coatings, finishing with a positive or negative layer, were tested, and different numbers of layers were investigated for their ability to interact and reduce the accumulation of PrPSc in scrapie prion infected ScGT1 and ScN2a cells. The particles efficiently hampered the accumulation of PrPSc in ScN2a cells and showed curing effects on ScGT1 cells with a nanoparticle concentration in the picomolar range. Finally, incubation periods of prion-infected mice treated with nanomolar concentrations of gold nanoparticles were significantly longer compared to untreated controls.

Constitutive Model Of Graded Micro-Structure Obtained Via Strain Induced Phase Transformation

CERN Document Server

Ortwein, Rafał

The literature review has been divided into three main sub-chapters. The first one is concentrated on the general information about stainless steels and their applications. It is important to perform a general overview and get an idea where the results of the present thesis could be applied. Description of all the brands of stainless steels, their microstructures and properties are important, as similar characteristics can be found in the newly created functionally graded structures. The second sub-chapter is an overview of the most important constitutive models and the experimental results for materials that undergo plastic strain induced phase transformation. Finally, the last one is devoted to functionally graded microstructures obtained via strain induced martensitic transformation – the subject of particular importance for the present thesis. As a general note, the literature review is organized mainly in a chronological order. In some cases similar publications or publications of the same Authors were...

Rapid and Quantitative Assay of Amyloid-Seeding Activity in Human Brains Affected with Prion Diseases.

Directory of Open Access Journals (Sweden)

Hanae Takatsuki

Full Text Available The infectious agents of the transmissible spongiform encephalopathies are composed of amyloidogenic prion protein, PrPSc. Real-time quaking-induced conversion can amplify very small amounts of PrPSc seeds in tissues/body fluids of patients or animals. Using this in vitro PrP-amyloid amplification assay, we quantitated the seeding activity of affected human brains. End-point assay using serially diluted brain homogenates of sporadic Creutzfeldt-Jakob disease patients demonstrated that 50% seeding dose (SD50 is reached approximately 10(10/g brain (values varies 10(8.79-10.63/g. A genetic case (GSS-P102L yielded a similar level of seeding activity in an autopsy brain sample. The range of PrPSc concentrations in the samples, determined by dot-blot assay, was 0.6-5.4 μg/g brain; therefore, we estimated that 1 SD50 unit was equivalent to 0.06-0.27 fg of PrPSc. The SD50 values of the affected brains dropped more than three orders of magnitude after autoclaving at 121°C. This new method for quantitation of human prion activity provides a new way to reduce the risk of iatrogenic prion transmission.

Process for obtaining cobalt and lanthanum nickelate

International Nuclear Information System (INIS)

Tapcov, V.; Samusi, N.; Gulea, A.; Horosun, I.; Stasiuc, V.; Petrenco, P.

1999-01-01

The invention relates to the process for obtaining polycrystalline ceramics of cobalt and lanthanum nickelate with the perovskite structure from coordinative hetero metallic compounds. The obtained products can be utilized in the industry in the capacity of catalysts. Summary of the invention consists in obtaining polycrystalline ceramics LaCoO 3 and LaNiO 3 with the perovskite structure by pyrolysis of the parent compounds, namely, the coordinative hetero metallic compounds of the lanthanum cobalt or lanthanum nickel. The pyrolysis of the parent compound runs during one hour at 800 C. The technical result of the invention consists in lowering the temperature of the parent compound pyrolysis containing the precise ratio of metals necessary for ceramics obtaining

Implications of prion adaptation and evolution paradigm for human neurodegenerative diseases.

Science.gov (United States)

Kabir, M Enamul; Safar, Jiri G

2014-01-01

There is a growing body of evidence indicating that number of human neurodegenerative diseases, including Alzheimer disease, Parkinson disease, fronto-temporal dementias, and amyotrophic lateral sclerosis, propagate in the brain via prion-like intercellular induction of protein misfolding. Prions cause lethal neurodegenerative diseases in humans, the most prevalent being sporadic Creutzfeldt-Jakob disease (sCJD); they self-replicate and spread by converting the cellular form of prion protein (PrP(C)) to a misfolded pathogenic conformer (PrP(Sc)). The extensive phenotypic heterogeneity of human prion diseases is determined by polymorphisms in the prion protein gene, and by prion strain-specific conformation of PrP(Sc). Remarkably, even though informative nucleic acid is absent, prions may undergo rapid adaptation and evolution in cloned cells and upon crossing the species barrier. In the course of our investigation of this process, we isolated distinct populations of PrP(Sc) particles that frequently co-exist in sCJD. The human prion particles replicate independently and undergo competitive selection of those with lower initial conformational stability. Exposed to mutant substrate, the winning PrP(Sc) conformers are subject to further evolution by natural selection of the subpopulation with the highest replication rate due to the lowest stability. Thus, the evolution and adaptation of human prions is enabled by a dynamic collection of distinct populations of particles, whose evolution is governed by the selection of progressively less stable, faster replicating PrP(Sc) conformers. This fundamental biological mechanism may explain the drug resistance that some prions gained after exposure to compounds targeting PrP(Sc). Whether the phenotypic heterogeneity of other neurodegenerative diseases caused by protein misfolding is determined by the spectrum of misfolded conformers (strains) remains to be established. However, the prospect that these conformers may evolve and

Removal of transmissible spongiform encephalopathy prion from large volumes of cell culture media supplemented with fetal bovine serum by using hollow fiber anion-exchange membrane chromatography.

Science.gov (United States)

Chou, Ming Li; Bailey, Andy; Avory, Tiffany; Tanimoto, Junji; Burnouf, Thierry

2015-01-01

Cases of variant Creutzfeldt-Jakob disease in people who had consumed contaminated meat products from cattle with bovine spongiform encephalopathy emphasize the need for measures aimed at preventing the transmission of the pathogenic prion protein (PrPSc) from materials derived from cattle. Highly stringent scrutiny is required for fetal bovine serum (FBS), a growth-medium supplement used in the production of parenteral vaccines and therapeutic recombinant proteins and in the ex vivo expansion of stem cells for transplantation. One such approach is the implementation of manufacturing steps dedicated to removing PrPSc from materials containing FBS. We evaluated the use of the QyuSpeed D (QSD) adsorbent hollow-fiber anion-exchange chromatographic column (Asahi Kasei Medical, Tokyo, Japan) for the removal of PrPSc from cell culture media supplemented with FBS. We first established that QSD filtration had no adverse effect on the chemical composition of various types of culture media supplemented with 10% FBS or the growth and viability characteristics of human embryonic kidney (HEK293) cells, baby hamster kidney (BHK-21) cells, African green monkey kidney (Vero) cells, and Chinese hamster ovary (CHO-k1) cells propagated in the various culture-medium filtrates. We used a 0.6-mL QSD column for removing PrPSc from up to 1000 mL of Dulbecco's modified Eagle's medium containing 10% FBS previously spiked with the 263K strain of hamster-adapted scrapie. The Western blot analysis, validated alongside an infectivity assay, revealed that the level of PrPSc in the initial 200mL flow-through was reduced by 2.5 to > 3 log10, compared with that of the starting material. These results indicate that QSD filtration removes PrPSc from cell culture media containing 10% FBS, and demonstrate the ease with which QSD filtration can be implemented in at industrial-scale to improve the safety of vaccines, therapeutic recombinant proteins, and ex vivo expanded stem cells produced using growth

Generalized cerebral atrophy seen on MRI in a naturally exposed animal model for creutzfeldt-jakob disease

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Dasanu Constantin A

2010-11-01

Full Text Available Abstract Background Magnetic resonance imaging has been used in the diagnosis of human prion diseases such as sCJD and vCJD, but patients are scanned only when clinical signs appear, often at the late stage of disease. This study attempts to answer the questions "Could MRI detect prion diseases before clinical symptoms appear?, and if so, with what confidence?" Methods Scrapie, the prion disease of sheep, was chosen for the study because sheep can fit into a human sized MRI scanner (and there were no large animal MRI scanners at the time of this study, and because the USDA had, at the time of the study, a sizeable sample of scrapie exposed sheep, which we were able to use for this purpose. 111 genetically susceptible sheep that were naturally exposed to scrapie were used in this study. Results Our MRI findings revealed no clear, consistent hyperintense or hypointense signal changes in the brain on either clinically affected or asymptomatic positive animals on any sequence. However, in all 37 PrPSc positive sheep (28 asymptomatic and 9 symptomatic, there was a greater ventricle to cerebrum area ratio on MRI compared to 74 PrPSc negative sheep from the scrapie exposed flock and 6 control sheep from certified scrapie free flocks as defined by immunohistochemistry (IHC. Conclusions Our findings indicate that MRI imaging can detect diffuse cerebral atrophy in asymptomatic and symptomatic sheep infected with scrapie. Nine of these 37 positive sheep, including 2 one-year old animals, were PrPSc positive only in lymph tissues but PrPSc negative in the brain. This suggests either 1 that the cerebral atrophy/neuronal loss is not directly related to the accumulation of PrPSc within the brain or 2 that the amount of PrPSc in the brain is below the detectable limits of the utilized immunohistochemistry assay. The significance of these findings remains to be confirmed in human subjects with CJD.

Structural and optical properties of Cu2SnS3 thin films obtained by SILAR method

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Aykut ASTAM

2017-06-01

Full Text Available Cu2SnS3 thin films were obtained by annealing of SILAR deposited films at 350°C for 1 hour in sulphur atmosphere. The structural and optical properties of the films were investigated using X-ray diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray analysis (EDAX and optical absorption measurements, before and after annealing. The XRD results showed that the annealing process transformed the crystal structure of the films from amorphous to polycrystalline. SEM images revealed that the surface morphology of films was changed after annealing while EDAX analysis showed that the films were excess in copper concentration before and after annealing. Optical absorption measurements confirmed that the direct band gap of films decreased from 1.27 eV to 1.21 eV with annealing.

Chemical structures and thermal properties of polyesters obtained from different samples of bio diesel epoxidized

International Nuclear Information System (INIS)

Samios, Dimitrios; Reiznautt, Quelen B.; Nicolau, Aline; Martini, Denise D.; Chagas, Arthur L. das

2009-01-01

In this work new structures from oligo esters and polyesters from different oils (olive oil, sunflower oil and linseed oil) were synthesized and characterized. Oligo esters and polyesters were synthesized from the reaction of fatty acid methyl epoxy-esters, obtained from different oils, with cis-1,2-cyclohexanedicarboxylic anhydride in the presence of triethylamine (TEA). Different amounts of the resin 1,4-butanediol diglycidyl ether (BDGE) were added in order to increase the capacity of crosslinking. The molar ratio of BDGE used in system was between 0 and 0.066. The intermediate structures, as well as the oligo esters and polyesters produced, were analyzed by using Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance ( 1 H - NMR). The thermal behavior of the products was realized through differential scanning calorimetry and Thermogravimetric analyses. The presence of BDGE in the materials chains increases the bonding capacity resulting in a higher molecular weight material which presents good thermal stability. (author)

Synthetic prions with novel strain-specified properties.

Science.gov (United States)

Moda, Fabio; Le, Thanh-Nhat T; Aulić, Suzana; Bistaffa, Edoardo; Campagnani, Ilaria; Virgilio, Tommaso; Indaco, Antonio; Palamara, Luisa; Andréoletti, Olivier; Tagliavini, Fabrizio; Legname, Giuseppe

2015-12-01

Prions are infectious proteins that possess multiple self-propagating structures. The information for strains and structural specific barriers appears to be contained exclusively in the folding of the pathological isoform, PrP(Sc). Many recent studies determined that de novo prion strains could be generated in vitro from the structural conversion of recombinant (rec) prion protein (PrP) into amyloidal structures. Our aim was to elucidate the conformational diversity of pathological recPrP amyloids and their biological activities, as well as to gain novel insights in characterizing molecular events involved in mammalian prion conversion and propagation. To this end we generated infectious materials that possess different conformational structures. Our methodology for the prion conversion of recPrP required only purified rec full-length mouse (Mo) PrP and common chemicals. Neither infected brain extracts nor amplified PrP(Sc) were used. Following two different in vitro protocols recMoPrP converted to amyloid fibrils without any seeding factor. Mouse hypothalamic GT1 and neuroblastoma N2a cell lines were infected with these amyloid preparations as fast screening methodology to characterize the infectious materials. Remarkably, a large number of amyloid preparations were able to induce the conformational change of endogenous PrPC to harbor several distinctive proteinase-resistant PrP forms. One such preparation was characterized in vivo habouring a synthetic prion with novel strain specified neuropathological and biochemical properties.

Structure and characteristics of functional powder composite materials obtained by spark plasma sintering

Science.gov (United States)

Oglezneva, S. A.; Kachenyuk, M. N.; Kulmeteva, V. B.; Ogleznev, N. B.

2017-07-01

The article describes the results of spark plasma sintering of ceramic materials based on titanium carbide, titanium carbosilicide, ceramic composite materials based on zirconium oxide, strengthened by carbon nanostructures and composite materials of electrotechnical purpose based on copper with addition of carbon structures and titanium carbosilicide. The research shows that the spark plasma sintering can achieve relative density of the material up to 98%. The effect of sintering temperature on the phase composition, density and porosity of the final product has been studied. It was found that with addition of carbon nanostructures the relative density and hardness decrease, but the fracture strength of ZrO2 increases up to times 2. The relative erosion resistance of the electrodes made of composite copper-based powder materials, obtained by spark plasma sintering during electroerosion treatment of tool steel exceeds that parameter of pure copper up to times 15.

Beyond PrPres Type 1/Type 2 Dichotomy in Creutzfeldt-Jakob Disease

Science.gov (United States)

Simon, Stéphanie; Lugan, Séverine; Bilheude, Jean-Marc; Perret-Liaudet, Armand; Ironside, James W.; Haik, Stéphane; Basset-Leobon, Christelle; Lacroux, Caroline; Peoch', Katell; Streichenberger, Nathalie; Langeveld, Jan; Head, Mark W.; Grassi, Jacques; Hauw, Jean-Jacques; Schelcher, Francois; Delisle, Marie Bernadette; Andréoletti, Olivier

2008-01-01

Sporadic Creutzfeldt-Jakob disease (sCJD) cases are currently subclassified according to the methionine/valine polymorphism at codon 129 of the PRNP gene and the proteinase K (PK) digested abnormal prion protein (PrPres) identified on Western blotting (type 1 or type 2). These biochemically distinct PrPres types have been considered to represent potential distinct prion strains. However, since cases of CJD show co-occurrence of type 1 and type 2 PrPres in the brain, the basis of this classification system and its relationship to agent strain are under discussion. Different brain areas from 41 sCJD and 12 iatrogenic CJD (iCJD) cases were investigated, using Western blotting for PrPres and two other biochemical assays reflecting the behaviour of the disease-associated form of the prion protein (PrPSc) under variable PK digestion conditions. In 30% of cases, both type 1 and type 2 PrPres were identified. Despite this, the other two biochemical assays found that PrPSc from an individual patient demonstrated uniform biochemical properties. Moreover, in sCJD, four distinct biochemical PrPSc subgroups were identified that correlated with the current sCJD clinico-pathological classification. In iCJD, four similar biochemical clusters were observed, but these did not correlate to any particular PRNP 129 polymorphism or western blot PrPres pattern. The identification of four different PrPSc biochemical subgroups in sCJD and iCJD, irrespective of the PRNP polymorphism at codon 129 and the PrPres isoform provides an alternative biochemical definition of PrPSc diversity and new insight in the perception of Human TSE agents variability. PMID:18389084

Oxidation of Helix-3 methionines precedes the formation of PK resistant PrP.

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Tamar Canello

2010-07-01

Full Text Available While elucidating the peculiar epitope of the alpha-PrP mAb IPC2, we found that PrPSc exhibits the sulfoxidation of residue M213 as a covalent signature. Subsequent computational analysis predicted that the presence of sulfoxide groups at both Met residues 206 and 213 destabilize the alpha-fold, suggesting oxidation may facilitate the conversion of PrPC into PrPSc. To further study the effect of oxidation on prion formation, we generated pAbs to linear PrP peptides encompassing the Helix-3 region, as opposed to the non-linear complexed epitope of IPC2. We now show that pAbs, whose epitopes comprise Met residues, readily detected PrPC, but could not recognize most PrPSc bands unless they were vigorously reduced. Next, we showed that the alpha-Met pAbs did not recognize newly formed PrPSc, as is the case for the PK resistant PrP present in lines of prion infected cells. In addition, these reagents did not detect intermediate forms such as PK sensitive and partially aggregated PrPs present in infected brains. Finally, we show that PrP molecules harboring the pathogenic mutation E200K, which is linked to the most common form of familial CJD, may be spontaneously oxidized. We conclude that the oxidation of methionine residues in Helix-3 represents an early and important event in the conversion of PrPC to PrPSc. We believe that further investigation into the mechanism and role of PrP oxidation will be central in finally elucidating the mechanism by which a normal cell protein converts into a pathogenic entity that causes fatal brain degeneration.

Obtaining source current density related to irregularly structured electromagnetic target field inside human body using hybrid inverse/FDTD method.

Science.gov (United States)

Han, Jijun; Yang, Deqiang; Sun, Houjun; Xin, Sherman Xuegang

2017-01-01

Inverse method is inherently suitable for calculating the distribution of source current density related with an irregularly structured electromagnetic target field. However, the present form of inverse method cannot calculate complex field-tissue interactions. A novel hybrid inverse/finite-difference time domain (FDTD) method that can calculate the complex field-tissue interactions for the inverse design of source current density related with an irregularly structured electromagnetic target field is proposed. A Huygens' equivalent surface is established as a bridge to combine the inverse and FDTD method. Distribution of the radiofrequency (RF) magnetic field on the Huygens' equivalent surface is obtained using the FDTD method by considering the complex field-tissue interactions within the human body model. The obtained magnetic field distributed on the Huygens' equivalent surface is regarded as the next target. The current density on the designated source surface is derived using the inverse method. The homogeneity of target magnetic field and specific energy absorption rate are calculated to verify the proposed method.

Glass-ceramics with multibarrier structure obtained from industrial waste

Energy Technology Data Exchange (ETDEWEB)

Berzina, L.; Cimdins, R.; Rozenstrauha, I. [Riga Tech. Univ. (Latvia). Fac. of Chem. Technol.; Bossert, J. [Technisches Inst.: Materialwissenschaft, Friedrich-Schiller-Univ., Jena (Germany); Kravtchenko, I. [Inst. for Problems of Material Science, Kiev (Ukraine)

1997-12-31

Recycling problem for various kind of waste is solved by processing the waste to ecological depositable products with multibarrier structure. In order to form a multibarrier structure the ecologically incompatible substances may be diluted and chemically bound until their recycling products gain a structure like natural mineral or glass (I. barrier). After that, remineralized materials are converted into a new product by melting or powder technology using an ecological compatible type of waste as a matrix phase (II. barrier). Waste which are treated this way could be applied to produce ceramic building materials and goods such as floor tiles, stone pavement and casting products. Industrial waste from the metallurgical factory in Latvia ``Liepajas metalurgs`` are metallurgical slag, filter dust, etching waste and sewage used in technologies. The main constituents of chemical compositions of these waste are: Fe, Ca, Si, Mg, Al, Mn etc. In some types of waste a small amount of ecologically risky elements such as Cr, Ni, Zr, Sn and Pb can occur. The combination of metallurgical waste with peat ashes from Riga thermal power station, oil shale ashes or glass waste under controlled sintering procedure gives bulk materials with surface or/and bulkcrystallization. The structure of glass-ceramics built this way may prevent the migration of ecologically risky elements into environment due to corrosion or friction. Physical-chemical properties and thermal behaviour (DTA, dilatometry, melting) of waste define the range of sintering for production of glass-ceramics (powder technology) and decorative glass-ceramic materials (melting and powder technology). (orig.) 5 refs.

Influence of the processing conditions on the structural properties of ZnO layers obtained by PECVD

Energy Technology Data Exchange (ETDEWEB)

Kitova, S; Danev, G, E-mail: skitova@clf.bas.b [Institute of Optical Materials and Technology ' Acad. J. Malinowski' , Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl.109, 1113 Sofia (Bulgaria)

2010-11-01

The plasma enhanced chemical vapor deposition (PECVD) is a powerful and flexible instrument for depositing thin layers, nanocomposites or nanostructures. In this work ZnO layers have been grown by metal-organic PECVD (RF - 13.56 MHz) on Si wafers. Zn acetylacetonate has been used as a precursor and oxygen as oxidant. The influence of the oxygen content in gas mixture, the total pressure, substrate temperature and ZnO seed layer on the structural properties of the layers deposited on Si wafers has been studied. ZnO layer properties were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD data have shown that all layers are crystalline with hexagonal wurtzite structure. The crystallites are preferentially oriented along c-axis direction perpendicular to the substrate surfaces. The results obtained indicate that by controlling the oxygen content in gas mixture, the total pressure and substrate temperature during the film growth one can control the formation of c-axis phase and the crystallite grain size. Nanorods with good alignment, vertically orientated to the substrate surface can be observed in the layers deposited at low content of O{sub 2} in plasma at substrate temperature of 400 {sup o}C. Due to their structural characteristics these layers are potential materials for preparing chemical- and biosensors where inherently large surface to volume ratio of structured materials are important prerequisite for enhanced sensitivity.

Hamiltonian structure of reduced fluid models for plasmas obtained from a kinetic description

International Nuclear Information System (INIS)

Guillebon, L. de; Chandre, C.

2012-01-01

We consider the Hamiltonian structure of reduced fluid models obtained from a kinetic description of collisionless plasmas by Vlasov–Maxwell equations. We investigate the possibility of finding Poisson subalgebras associated with fluid models starting from the Vlasov–Maxwell Poisson algebra. In this way, we show that the only possible Poisson subalgebra involves the moments of zeroth and first order of the Vlasov distribution, meaning the fluid density and the fluid velocity. We find that the bracket derived in [B.A. Shadwick, G.M. Tarkenton, E.H. Esarey, Phys. Rev. Lett. 93 (2004) 175002] which involves moments of order 2 is not a Poisson bracket since it does not satisfy the Jacobi identity. -- Highlights: ► We investigate fluid reductions from the Vlasov–Maxwell Poisson bracket. ► The only Poisson subalgebra involves fluid density and fluid velocity. ► The bracket derived in [B.A. Shadwick, G.M. Tarkenton, E.H. Esarey, Phys. Rev. Lett. 93 (2004) 175002] is not Hamiltonian.

Structure and magnetic properties of GdxY1−xFeO3 obtained by mechanosynthesis

International Nuclear Information System (INIS)

Bolarín-Miró, A.M.; Sánchez-De Jesús, F.; Cortés-Escobedo, C.A.; Valenzuela, R.; Ammar, S.

2014-01-01

Highlights: • Orthohombic GDxY1-xFeO3 was obtained by mechanosynthesis after 5 h of milling. • Mechanosynthesized GdxY1-xFeO3 show weak ferromagnetic behavior. • Mechanosynthesis promotes unexpected magnetic properties in GdxY1-xFeO3. • The maximum magnetization that was reached 7.7 emu/g for Gdo.75Y0.25FeO3. • For Gd0.5Y0.5FeO3, the magnetization decreases down to 2.1 emu/g. -- Abstract: Solid solutions of yttrium–gadolinium orthoferrites Gd x Y 1−x FeO 3 (0 ⩽ x ⩽ 1) were prepared by high-energy ball milling. The aim of this work was to study the influence of the synthesis parameters on the crystal structure and the magnetic behavior of these solid solutions. The precursors, Fe 2 O 3 , Y 2 O 3 and Gd 2 O 3 , mixed in a stoichiometric ratio to obtain these orthoferrites, were milled for different times (up to 5 h). X-ray diffraction and Rietveld refinement were used to elucidate the phase transformation as a function of the milling time. Results showed the complete formation of orthoferrite with an orthorhombic structure (S.G. Pbnm) without any annealing after 5 h of milling for all of the compositions. The effect of the synthesis process and the x value on the crystal structure and the magnetic properties were also studied. All of the synthesized powders demonstrated weak ferromagnetic behavior. In particular, an increase in the maximum magnetization for all the compositions was found, with a maximum that reached 7.7 emu/g for Gd 0.75 Y 0.25 FeO 3 . For Gd 0.5 Y 0.5 FeO 3 , the magnetization decreases down to 2.1 emu/g. A small contamination of metallic Fe was confirmed through electron spin resonance experiments

Structural parameters of polyethylenes obtained using a palladium catalyst: dilute solution and solid state studies

International Nuclear Information System (INIS)

Meneghetti, Simoni Plentz; Lutz, Pierre J.; Duval, M.; Kress, Jacky; Lapp, A.

2001-01-01

Polyethylenes were obtained using palladium catalyst [(Ar N=C(Me)-C(Me)=N Ar) Pd(CH 2 ) 3 (COOMe)] + BAr' 4 - (VERSIPOL TM ); Ar2,6-i-Pr 2 -C 6 H 3 and Ar'3,5-(CF 3 ) 2 -C 6 H 3 . The combination of dilute solution and solid state characterization of these polyethylenes revealed strong differences between structural parameters of samples prepared under almost identical conditions except ethylene pressure (6, 3 and 1 bar). These differences can be explained by the fact that samples prepared at 6 bar are almost linear, with only a few short branches, whereas those synthesized at 1 bar are highly branched or even hyper branched. (author)

Thermal and structural study of guava (Psidium guajava L powders obtained by two dehydration methods

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Coralia Osorio

2011-01-01

Full Text Available Two food products (powders were obtained by hot-air drying or lyophilisation methods on the whole guava fruits. The powders were characterised by sensory and thermal analyses (TGA-DSC, infrared spectroscopy (IR, X-ray diffraction (XRD and scanning electron microscopy (SEM. Thermal, morphological and structural characterisations showed a similar behaviour for the two solids. TGA-DSC and IR showed the presence of pectin as the main constituent of solids. A semi-crystalline profile was evidenced by XRD, and lamellar/spherical morphologies were observed by SEM. Sensory analyses revealed an aroma highly related to guava. These value-added food products are an alternative to process guava and avoid loss during postharvest handling.

Sialic Acid on the Glycosylphosphatidylinositol Anchor Regulates PrP-mediated Cell Signaling and Prion Formation.

Science.gov (United States)

Bate, Clive; Nolan, William; Williams, Alun

2016-01-01

The prion diseases occur following the conversion of the cellular prion protein (PrP(C)) into disease-related isoforms (PrP(Sc)). In this study, the role of the glycosylphosphatidylinositol (GPI) anchor attached to PrP(C) in prion formation was examined using a cell painting technique. PrP(Sc) formation in two prion-infected neuronal cell lines (ScGT1 and ScN2a cells) and in scrapie-infected primary cortical neurons was increased following the introduction of PrP(C). In contrast, PrP(C) containing a GPI anchor from which the sialic acid had been removed (desialylated PrP(C)) was not converted to PrP(Sc). Furthermore, the presence of desialylated PrP(C) inhibited the production of PrP(Sc) within prion-infected cortical neurons and ScGT1 and ScN2a cells. The membrane rafts surrounding desialylated PrP(C) contained greater amounts of sialylated gangliosides and cholesterol than membrane rafts surrounding PrP(C). Desialylated PrP(C) was less sensitive to cholesterol depletion than PrP(C) and was not released from cells by treatment with glimepiride. The presence of desialylated PrP(C) in neurons caused the dissociation of cytoplasmic phospholipase A2 from PrP-containing membrane rafts and reduced the activation of cytoplasmic phospholipase A2. These findings show that the sialic acid moiety of the GPI attached to PrP(C) modifies local membrane microenvironments that are important in PrP-mediated cell signaling and PrP(Sc) formation. These results suggest that pharmacological modification of GPI glycosylation might constitute a novel therapeutic approach to prion diseases. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Optical and structural properties of FeSe2 thin films obtained by selenization of sprayed amorphous iron oxide films

International Nuclear Information System (INIS)

Ouertani, B.; Ouerfelli, J.; Saadoun, M.; Zribi, M.; Rabha, M.Ben; Bessais, B.; Ezzaouia, H.

2006-01-01

We report in this work the optical and structural properties of iron diselenide films (FeSe 2 ) obtained by selenization under vacuum of amorphous iron oxide films predeposited by spray pyrolysis. The structure of the FeSe 2 films was investigated by scanning electron microscopy (SEM), microprobe analyses, atomic force microscopy (AFM) and X-ray diffraction (XRD). XRD and micro-probe analyses showed that FeSe 2 as well as FeSe 2-x phases begin to appear at a selenization temperature of 500 deg. C. As the selenization temperature rises, the iron diselenide films become more stoichiometric with a dominance of the FeSe 2 phase. At 550 deg. C, a single FeSe 2 phase having good crystallinity was obtained. At 600 deg. C, two phases were detected: the major one corresponds to Fe 3 O 4 , and the minor one to FeSe 2 . SEM surface views show that FeSe 2 films have granular structure with small spherical crystallites. However, layered and clustered FeSe 2 films were found, respectively, at 550 deg. C and 600 deg. C. Absorption measurements show that iron diselenide films have a direct and an indirect gaps of about 1.03 eV and 0.3 eV, which were suggested to be due to the stoichiometric FeSe 2 phase and to a Fe-rich non-stoichiometric phase, respectively

Structural analysis and magnetic properties of solid solutions of Co–Cr system obtained by mechanical alloying

International Nuclear Information System (INIS)

Betancourt-Cantera, J.A.; Sánchez-De Jesús, F.; Bolarín-Miró, A.M.; Betancourt, I.; Torres-Villaseñor, G.

2014-01-01

In this paper, a systematic study on the structural and magnetic properties of Co 100−x Cr x alloys (0 1−x Cr x (0 2 /kg) for the Co 90 Cr 10 , which decreases with the increasing of the Cr content up to x=80, as a consequence of the dilution effect of the magnetic moment which is caused by the Cr content and by the competition between ferromagnetic and antiferromagnetic exchange interactions. The coercivity increases up to 34 kA/m (435 Oe) for Co 40 Cr 60 . For Cr rich compositions, it is observed an important decrease reaching 21 kA/m (272 Oe) for Co 10 Cr 90, it is related to the grain size and the structural change. Besides, the magnetic anisotropy constant was determined for each composition. Magnetic thermogravimetric analysis allowed to obtain Curie temperatures corresponding to the formation of hcp-Co(Cr) and fcc-Co(Cr) solid solutions. - Highlights: • Mechanical alloying (MA) induces the formation of solid solutions of Co–Cr system in non-equilibrium. • We report the crystal structure and the magnetic behavior of Co–Cr alloys produced by MA. • MA improves the magnetic properties of Co–Cr system

Evaluation of the structure and microstructure of NixMg1-xO oxides obtained by co-precipitation

International Nuclear Information System (INIS)

Martinez L, G.; Kryshtab, T.; Hesiquio G, M.; Kryvko, A.

2013-01-01

Ni x Mg 1-x O oxides were prepared by thermal treatment at temperatures of 400, 600 and 800 C from a hydrotalcite-like precursor obtained by co-precipitation at constant ph. The oxides obtained were characterized by X-ray diffraction methods. From the obtained results we concluded that the oxides calcined at temperatures of 400, and 600 C are unstable that means that there exists the effect of memory and with a time they return to the precursor. Presence of Ni in Mg oxide provides stability of the compounds thermally treated at 800 C. In order to analyze the structure and microstructure, the reflections 111, 200 and 220 were used. The positions of the maxima of the diffraction peaks are shifted with respect to the simulated ones for Mg O and Ni O. This result reveals that in solid solutions studied compressive strains or vacation are present. The parameters of the microstructure (coherent domain size and micro deformations) were evaluated. The coherent domain size was found to be in the range of 8 - 10 nm and the presence of residual strains of micro deformation can be associated with the existence of extended defects. (Author)

The amino-terminal structure of human fragile X mental retardation protein obtained using precipitant-immobilized imprinted polymers

Science.gov (United States)

Hu, Yufeng; Chen, Zhenhang; Fu, Yanjun; He, Qingzhong; Jiang, Lun; Zheng, Jiangge; Gao, Yina; Mei, Pinchao; Chen, Zhongzhou; Ren, Xueqin

2015-03-01

Flexibility is an intrinsic property of proteins and essential for their biological functions. However, because of structural flexibility, obtaining high-quality crystals of proteins with heterogeneous conformations remain challenging. Here, we show a novel approach to immobilize traditional precipitants onto molecularly imprinted polymers (MIPs) to facilitate protein crystallization, especially for flexible proteins. By applying this method, high-quality crystals of the flexible N-terminus of human fragile X mental retardation protein are obtained, whose absence causes the most common inherited mental retardation. A novel KH domain and an intermolecular disulfide bond are discovered, and several types of dimers are found in solution, thus providing insights into the function of this protein. Furthermore, the precipitant-immobilized MIPs (piMIPs) successfully facilitate flexible protein crystal formation for five model proteins with increased diffraction resolution. This highlights the potential of piMIPs for the crystallization of flexible proteins.

Structural and electrical properties of copper-nickel-aluminum alloys obtained by conventional powder metallurgy method

International Nuclear Information System (INIS)

Monteiro, Waldemar A.; Carrio, Juan A.G.; Silveira, C.R. da; Pertile, H.K.S.

2009-01-01

This work looked for to search out systematically, in scale of laboratory, copper-nickel-aluminum alloys (Cu-Ni-Al) with conventional powder metallurgy processing, in view of the maintenance of the electric and mechanical properties with the intention of getting electric connectors of high performance or high mechanical damping. After cold uniaxial pressing (1000 kPa), sintering (780 deg C) and convenient homogenization treatments (500 deg C for different times) under vacuum (powder metallurgy), the obtained Cu-Ni-Al alloys were characterized by optical microscopy, electrical conductivity, Vickers hardness. X rays powder diffraction data were collected for the sintered samples in order to a structural and microstructural analysis. The comparative analysis is based on the sintered density, hardness, macrostructures and microstructures of the samples. (author)

Structural analysis of a sulfated polysaccharidic fraction obtained from the coenocytic green seaweed Caulerpa cupressoides var. lycopodium

Directory of Open Access Journals (Sweden)

José Ariévilo Gurgel Rodrigues

2014-04-01

Full Text Available Researches on structural chemistry of sulfated polysaccharides (SPs have been mainly focused on red and brown algae. Caulerpa cupressoides var. lycopodium (Chlorophyta contains three SPs fractions (Cc-SP1, Cc-SP2 and Cc-SP3. Cc-SP1 and Cc-SP2 had anticoagulant (in vitro and anti- and prothrombotic, antinociceptive and/or anti-inflammatory (in vivo effects. However, their structural features have not yet been investigated. This study analyzed the chemical composition, elemental microanalysis and structural features by infrared (IR and nuclear magnetic resonance (1H NMR spectroscopy of Cc-SPs. Fractionation of SPs by DEAE-cellulose yielded Cc-SP1, Cc-SP2 and CcSP3 containing differences among the relative proportions of sulfate (14.67-26.72%, total sugars (34.92-49.73% and uronic acid (7.15-7.22%. Carbon (21.76-29.62%, sulfate (2.16-4.55%, nitrogen (0.85-1.57% and hydrogen (4.57-5.86% contents were obtained using a CHN equipment. Data from IR indicated occurrence of sulfate ester, galactose-6-sulfate, uronic acid and glycoside linkages. For 1H NMR spectrum of the soluble Cc-SP1 fraction, it was mainly found β-galactopyranose residues and CH3 group. The results showed that Cc-SPs fractions have some structural features similar to others studied Caulerpaceae SPs.

Electronic structure of BaFe2As2 as obtained from DFT/ASW first-principles calculations

KAUST Repository

Schwingenschlögl, Udo

2010-07-02

We use ab-initio calculations based on the augmented spherical wave method within density functional theory to study the magnetic ordering and Fermi surface of BaFe2As2, the parent compound of the hole-doped iron pnictide superconductors (K,Ba)Fe2As2, for the tetragonal I4/mmm as well as the orthorhombic Fmmm structure. In comparison to full potential linear augmented plane wave calculations, we obtain significantly smaller magnetic energies. This finding is remarkable, since the augmented spherical wave method, in general, is known for a most reliable description of magnetism. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Neuronal Culture System to Detect Prion Synaptotoxicity.

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Cheng Fang

2016-05-01

Full Text Available Synaptic pathology is an early feature of prion as well as other neurodegenerative diseases. Although the self-templating process by which prions propagate is well established, the mechanisms by which prions cause synaptotoxicity are poorly understood, due largely to the absence of experimentally tractable cell culture models. Here, we report that exposure of cultured hippocampal neurons to PrPSc, the infectious isoform of the prion protein, results in rapid retraction of dendritic spines. This effect is entirely dependent on expression of the cellular prion protein, PrPC, by target neurons, and on the presence of a nine-amino acid, polybasic region at the N-terminus of the PrPC molecule. Both protease-resistant and protease-sensitive forms of PrPSc cause dendritic loss. This system provides new insights into the mechanisms responsible for prion neurotoxicity, and it provides a platform for characterizing different pathogenic forms of PrPSc and testing potential therapeutic agents.

Grass Plants Bind, Retain, Uptake, and Transport Infectious Prions

Directory of Open Access Journals (Sweden)

Sandra Pritzkow

2015-05-01

Full Text Available Prions are the protein-based infectious agents responsible for prion diseases. Environmental prion contamination has been implicated in disease transmission. Here, we analyzed the binding and retention of infectious prion protein (PrPSc to plants. Small quantities of PrPSc contained in diluted brain homogenate or in excretory materials (urine and feces can bind to wheat grass roots and leaves. Wild-type hamsters were efficiently infected by ingestion of prion-contaminated plants. The prion-plant interaction occurs with prions from diverse origins, including chronic wasting disease. Furthermore, leaves contaminated by spraying with a prion-containing preparation retained PrPSc for several weeks in the living plant. Finally, plants can uptake prions from contaminated soil and transport them to aerial parts of the plant (stem and leaves. These findings demonstrate that plants can efficiently bind infectious prions and act as carriers of infectivity, suggesting a possible role of environmental prion contamination in the horizontal transmission of the disease.

Structural and ferroelectric properties of Sr1−xBaxBi2Nb2O9 thin films obtained by dip-coating

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Y. González-Abreu

2017-10-01

Full Text Available The paper presents the structural and ferroelectric results for Sr1−xBaxBi2Nb2O9(x=0.30; 0.85 thin films, which were obtained by using dip-coating. The solutions containing the desirable ions were prepared from the powders of the previous studied ceramic samples. The films were deposited at room temperature on Fluorine-doped Tin Oxide (FTO substrates and submitted to a heat treatment for crystallization. The films were characterized by using scanning microscopy electronic, energy dispersive spectroscopy and ellipsometry. Hysteresis ferroelectric loops were obtained, at room temperature, by using a Sawyer-Tower circuit at several frequencies. A well-defined grain structure was observed for both compositions. The energy dispersive spectroscopy (EDS measurements revealed the presence of the corresponding elements from the chemical composition of the ceramic systems. The band-gap energy was around 3.3eV for both samples. Typical hysteresis loops for normal and relaxor ferroelectrics were obtained for x=0.30 and 0.85, respectively.

A comparison between the Structural Results obtained by X-ray Single Crystal Data and by Neutron Powder Data for BaVs/sb3/

International Nuclear Information System (INIS)

Marezio, M.

1986-01-01

The structure of BaVs/sb3/, as refined from X-ray single-crystal data to an R factor of 0.011, is compared to the structure of the same compound obtained from neutron powder data (Rsb(ro) = 6.82, Rsb(psilon) = 4.09). As expected, the X-ray standard deviations of the positional and thermal parameters are smaller than the corresponding neutron standard deviations. However, the dynamical disorder deduced from the anomalously large thermal vibrations of the vanadium atoms obtained from the X-ray data is also evidenced by the neutron refinement. On the other hand, the neutron standard deviations of the lattice parameters are smaller than the X-ray counterparts

Wood-Polymer composites obtained by gamma irradiation

International Nuclear Information System (INIS)

Gago, J.; Lopez, A.; Rodriguez, J.; Santiago, J.; Acevedo, M.

2007-01-01

In this work we impregnate three Peruvian woods (Calycophy spruceanum Be, Aniba amazonica Meiz and Hura crepitans L) with styrene-polyester resin and methyl methacrylate. The polymerization of the system was promoted by gamma radiation and the experimental optimal condition was obtained with styrene-polyester 1:1 and 15 kGy. The obtained composites show reduced water absorption and better mechanical properties compared to the original wood. The structure of the wood-polymer composites was studied by light microscopy. Water absorption and hardness were also obtained

Wood-Polymer composites obtained by gamma irradiation

Science.gov (United States)

Gago, J.; López, A.; Santiago, J.; Acevedo, M.; Rodríguez, J.

2007-10-01

In this work we impregnate three Peruvian woods (Calycophy spruceanum Be, Aniba amazonica Meiz and Hura crepitans L) with styrene-polyester resin and methyl methacrylate. The polymerization of the system was promoted by gamma radiation and the experimental optimal condition was obtained with styrene-polyester 1:1 and 15 kGy. The obtained composites show reduced water absorption and better mechanical properties compared to the original wood. The structure of the wood-polymer composites was studied by light microscopy. Water absorption and hardness were also obtained.

Crystal structure of importin-{alpha} complexed with a classic nuclear localization sequence obtained by oriented peptide library screening

Energy Technology Data Exchange (ETDEWEB)

Takeda, A.A.S.; Fontes, M.R.M. [UNESP, Universidade Estadual Paulista, Botucatu, SP (Brazil); Yang, S.N.Y. [University of Melbourne, Melbourne (Australia); Harris, J.M. [Queensland University of Technology, Brisbane (Australia); Jans, D.A. [Monash University, Clayton (Australia); Kobe, B. [University of Queensland, Brisbane, QU (Australia)

2012-07-01

Full text: Importin-{alpha} (Imp{alpha}) plays a role in the classical nuclear import pathway, binding to cargo proteins with activities in the nucleus. Different Imp{alpha} paralogs responsible for specific cargos can be found in a single organism. The cargos contain nuclear localization sequences (NLSs), which are characterized by one or two clusters of basic amino acids (monopartite and bipartite NLSs, respectively). In this work we present the crystal structure of Imp{alpha} from M. musculus (residues 70-529, lacking the auto inhibitory domain) bound to a NLS peptide (pepTM). The peptide corresponds to the optimal sequence obtained by an oriented peptide library experiment designed to probe the specificity of the major NLS binding site. The peptide library used five degenerate positions and identified the sequence KKKRR as the optimal sequence for binding to this site for mouse Imp{alpha} (70-529). The protein was obtained using an E. coli expression system and purified by affinity chromatography followed by an ion exchange chromatography. A single crystal of Imp{alpha} -pepTM complex was grown by the hanging drop method. The data were collected using the Synchrotron Radiation Source LNLS, Brazil and processed to 2.3. Molecular replacement techniques were used to determine the crystal structure. Electron density corresponding to the peptide was present in both major and minor binding sites The peptide is bound to Imp{alpha} similar as the simian virus 40 (SV40) large tumour (T)-antigen NLS. Binding assays confirmed that the peptide bound to Imp{alpha} with low nM affinities. This is the first time that structural information has been linked to an oriented peptide library screening approach for importin-{alpha}; the results will contribute to understanding of the sequence determinants of classical NLSs, and may help identify as yet unidentified classical NLSs in novel proteins. (author)

Synthesis, optimization and structural characterization of a chitosan-glucose derivative obtained by the Maillard reaction.

Science.gov (United States)

Gullón, Beatriz; Montenegro, María I; Ruiz-Matute, Ana I; Cardelle-Cobas, Alejandra; Corzo, Nieves; Pintado, Manuela E

2016-02-10

Chitosan (Chit) was submitted to the Maillard reaction (MR) by co-heating a solution with glucose (Glc). Different reaction conditions as temperature (40, 60 and 80 °C), Glc concentration (0.5%, 1%, and 2%, w/v), and reaction time (72, 52 and 24h) were evaluated. Assessment of the reaction extent was monitored by measuring changes in UV absorbance, browning and fluorescence. Under the best conditions, 2% (w/v) of Chit, 2% (w/v) of Glc at 60°C and 32 h of reaction time, a chitosan-glucose (Chit-Glc) derivative was purified and submitted to structural characterization to confirm its formation. Analysis of its molecular weight (MW) and the degree of substitution (DS) was carried out by HPLC-Size Exclusion Chromatography (SEC) and a colloid titration method, respectively. FT-IR and (1)H NMR were also used to analyze the functional groups and evaluate the introduction of Glc into the Chit molecule. According to our objectives, the results obtained in this work allowed to better understand the key parameters influencing the MR with Chit as well as to confirm the successful introduction of Glc into the Chit molecule obtaining a Chit-Glc derivative with a DS of 64.76 ± 4.40% and a MW of 210.37 kDa. Copyright © 2015 Elsevier Ltd. All rights reserved.

Enzymatic formulation capable of degrading scrapie prion under mild digestion conditions.

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Emeka A Okoroma

Full Text Available The prion agent is notoriously resistant to common proteases and conventional sterilisation procedures. The current methods known to destroy prion infectivity such as incineration, alkaline and thermal hydrolysis are harsh, destructive, environmentally polluting and potentially hazardous, thus limit their applications for decontamination of delicate medical and laboratory devices, remediation of prion contaminated environment and for processing animal by-products including specified risk materials and carcases. Therefore, an environmentally friendly, non-destructive enzymatic degradation approach is highly desirable. A feather-degrading Bacillus licheniformis N22 keratinase has been isolated which degraded scrapie prion to undetectable level of PrP(Sc signals as determined by Western Blot analysis. Prion infectivity was verified by ex vivo cell-based assay. An enzymatic formulation combining N22 keratinase and biosurfactant derived from Pseudomonas aeruginosa degraded PrP(Sc at 65 °C in 10 min to undetectable level -. A time-course degradation analysis carried out at 50 °C over 2 h revealed the progressive attenuation of PrP(Sc intensity. Test of residual infectivity by standard cell culture assay confirmed that the enzymatic formulation reduced PrP(Sc infectivity to undetectable levels as compared to cells challenged with untreated standard scrapie sheep prion (SSBP/1 (p-value = 0.008 at 95% confidence interval. This novel enzymatic formulation has significant potential application for prion decontamination in various environmentally friendly systems under mild treatment conditions.

Comparison among structural characteristics of Ce1-xCuxO2 nanocatalysts obtained by two methods of distinct synthesis

International Nuclear Information System (INIS)

Neiva, L.S.; Bispo, A.; Santos, P.T.A.; Costa, A.C.F.M.; Gama, L.; Mascarenhas, A.J.S.

2009-01-01

The objective this work is to synthesize nano catalysts Ce 1-x Cu x O 2 type by the synthesis methods of the combustion reaction and Pechini. The value of the concentration (x) of the element dope (Cu) varies between 0,1 and 0,5 mols. It intends evaluate that form the synthesis method influences in the physical structural characteristics of this material. nano catalysts were characterized by ray- X diffraction. The results showed nano catalysts formation with a formed structure for the most part by the phase CeO 2 , as it was expected, since this is the hostess matrix of the element dope (Cu). Nano catalysts obtained by the method Pechini presents crystallinity larger deg, according with patterns of ray-X. Thus, it was concluded that synthesis employee method the kind in the methodology, as well as the value of the concentration of the element dope has influence on the final structural characteristics of the developed material. (author)

Structure and mechanical properties of parts obtained by selective laser melting of metal powder based on intermetallic compounds Ni3Al

Science.gov (United States)

Smelov, V. G.; Sotov, A. V.; Agapovichev, A. V.; Nosova, E. A.

2018-03-01

The structure and mechanical properties of samples are obtained from metal powder based on intermetallic compound by selective laser melting. The chemical analysis of the raw material and static tensile test of specimens were made. Change in the samples’ structure and mechanical properties after homogenization during four and twenty-four hours were investigated. A small-sized combustion chamber of a gas turbine engine was performed by the selective laser melting method. The print combustion chamber was subjected to the gas-dynamic test in a certain temperature and time range.

The comparison of the structures of some cationic forms of clinoptilolite obtained from Manisa-Gordes in Turkey using their XRD spectrums

International Nuclear Information System (INIS)

Izci, E.; Orhun, O.

2000-01-01

In this study, at room temperature, XRD spectrums of Na, Ca, Li, Pb and natural forms of clinoptilolite, which is a natural zeolite obtained from Manisa-Gordes in Turkey, were taken and compared with each other according to their structures. Firstly, clinoptilolite samples, whose, diameters are smaller than 63 μm, were purified by HCl. Thus, impurities through the channels of clinoptilolite samples, were removed from their structures. Then, the samples washed several times by deionised water and filtered. So, HCl was removed from structures of these samples. Na, Ca, Li, Pb ionic forms of clinoptilolite were prepared by using batch method. XRD apparatus from Rigaku-Rint 2000 series. Comparing of XRD spectrums of these ionic and natural forms of clinoptilolite and finding the variations of their spectrums, what changes in their structures could be, were investigated. (authors)

Structural and morphological characterization of TiO2-ZrO2 powders obtained by the polymeric precursors method

International Nuclear Information System (INIS)

Ribeiro, M.A.; Gama, L.; Bispo, A.; Neiva, L.S.; Bernardi, M.I.B.; Kiminami, R.H.G.A.

2010-01-01

This work aims to characterize the structure and morphology of TiO 2 -ZrO 2 powders obtained by polymeric precursor method. For this we studied the following compositions: 0.25, 0.5 and 0.75 moles of Zr and calcined at 800 deg C for one hour. The powders obtained were characterized by XRD, SEM and nitrogen adsorption (BET). The analysis of X-ray diffraction showed that the powders had a phase of TiO 2 in the anatase form and a tetragonal phase of ZrO 2 . The crystallite size was between 8, 13 and 11 nm respectively. The analysis of scanning electron microscopy showed the growth of ZrO 2 nanoparticles and that these comprise spherical agglomerates of less than 100 nm. Particle size determined by the BET ranging 28.1-29.5 nm, showing thereby the character of nanosized powders. (author)

Experimental results obtained at GANIL

International Nuclear Information System (INIS)

Borrel, V.

1993-01-01

A review of experimental results obtained at GANIL on the study of nuclear structure and nuclear reactions with secondary radioactive beams is presented. Mass measurements by means of the GANIL cyclotrons are described. The possibilities of GANIL/LISE3 for the production and separation of radioactive beams are illustrated through a large variety of experiments. (author). 19 refs., 8 figs

Role of Prion Replication in the Strain-dependent Brain Regional Distribution of Prions.

Science.gov (United States)

Hu, Ping Ping; Morales, Rodrigo; Duran-Aniotz, Claudia; Moreno-Gonzalez, Ines; Khan, Uffaf; Soto, Claudio

2016-06-10

One intriguing feature of prion diseases is their strain variation. Prion strains are differentiated by the clinical consequences they generate in the host, their biochemical properties, and their potential to infect other animal species. The selective targeting of these agents to specific brain structures have been extensively used to characterize prion strains. However, the molecular basis dictating strain-specific neurotropism are still elusive. In this study, isolated brain structures from animals infected with four hamster prion strains (HY, DY, 139H, and SSLOW) were analyzed for their content of protease-resistant PrP(Sc) Our data show that these strains have different profiles of PrP deposition along the brain. These patterns of accumulation, which were independent of regional PrP(C) production, were not reproduced by in vitro replication when different brain regions were used as substrate for the misfolding-amplification reaction. On the contrary, our results show that in vitro replication efficiency depended exclusively on the amount of PrP(C) present in each part of the brain. Our results suggest that the variable regional distribution of PrP(Sc) in distinct strains is not determined by differences on prion formation, but on other factors or cellular pathways. Our findings may contribute to understand the molecular mechanisms of prion pathogenesis and strain diversity. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Prion protein β2–α2 loop conformational landscape

Science.gov (United States)

Caldarulo, Enrico; Wüthrich, Kurt; Parrinello, Michele

2017-01-01

In transmissible spongiform encephalopathies (TSEs), which are lethal neurodegenerative diseases that affect humans and a wide range of other mammalian species, the normal “cellular” prion protein (PrPC) is transformed into amyloid aggregates representing the “scrapie form” of the protein (PrPSc). Continued research on this system is of keen interest, since new information on the physiological function of PrPC in healthy organisms is emerging, as well as new data on the mechanism of the transformation of PrPC to PrPSc. In this paper we used two different approaches: a combination of the well-tempered ensemble (WTE) and parallel tempering (PT) schemes and metadynamics (MetaD) to characterize the conformational free-energy surface of PrPC. The focus of the data analysis was on an 11-residue polypeptide segment in mouse PrPC(121–231) that includes the β2–α2 loop of residues 167–170, for which a correlation between structure and susceptibility to prion disease has previously been described. This study includes wild-type mouse PrPC and a variant with the single-residue replacement Y169A. The resulting detailed conformational landscapes complement in an integrative manner the available experimental data on PrPC, providing quantitative insights into the nature of the structural transition-related function of the β2–α2 loop. PMID:28827331

Structural analysis of CdS thin films obtained by multiple dips of oscillating chemical bath

Energy Technology Data Exchange (ETDEWEB)

Gutierrez Lazos, C.D. [Seccion de Electronica del Estado Solido, Centro de Investigacion y de Estudios Avanzados, Av. Instituto Politecnico Nacional 2508, Col. San Pedro Zacatenco, 07360 Mexico, D.F. (Mexico); Rosendo, E., E-mail: erosendo@siu.buap.m [Centro de Investigacion en Dispositivos Semiconductores, Universidad Autonoma de Puebla, 14 Sur y San Claudio, Col. San Manuel, C.P. 72570, Puebla (Mexico); Ortega, M. [Seccion de Electronica del Estado Solido, Centro de Investigacion y de Estudios Avanzados, Av. Instituto Politecnico Nacional 2508, Col. San Pedro Zacatenco, 07360 Mexico, D.F. (Mexico); Oliva, A.I. [Departamento de Fisica Aplicada, Centro de Investigacion y de Estudios Avanzados, Unidad Merida, A.P. 73 Cordemex, 97310 Merida, Yucatan (Mexico); Tapia, O.; Diaz, T.; Juarez, H.; Garcia, G. [Centro de Investigacion en Dispositivos Semiconductores, Universidad Autonoma de Puebla, 14 Sur y San Claudio, Col. San Manuel, C.P. 72570, Puebla (Mexico); Rubin, M. [Facultad de Ciencias de la Computacion, 14 Sur y San Claudio, Col. San Manuel, C.P. 72570, Puebla (Mexico)

2009-11-25

Highly oriented CdS thin films with thicknesses greater than 1 mum were deposited by multiple dips, using oscillating chemical bath deposition (OCBD) at the bath temperature of 75 deg. C, and deposition time ranging from 15 to 75 min for a single dip. Samples with different thickness were prepared by repeating the deposition process for two and three times. The films deposited by a single dip have the alpha-greenockite structure showing the (0 0 2) as preferred orientation, as indicated by the X-ray diffraction measurements. This notable characteristic is preserved in the samples obtained from two or three dips. The crystallite size for the samples deposited by a single dip depends on the deposition time, because it varied from 23 to 37 nm as the deposition time increased. Nevertheless for samples deposited by two and three dips, the grain size shows no noticeable change, being about 22 nm.

A closer look at prion strains

Science.gov (United States)

Solforosi, Laura; Milani, Michela; Mancini, Nicasio; Clementi, Massimo; Burioni, Roberto

2013-01-01

Prions are infectious proteins that are responsible for transmissible spongiform encephalopathies (TSEs) and consist primarily of scrapie prion protein (PrPSc), a pathogenic isoform of the host-encoded cellular prion protein (PrPC). The absence of nucleic acids as essential components of the infectious prions is the most striking feature associated to these diseases. Additionally, different prion strains have been isolated from animal diseases despite the lack of DNA or RNA molecules. Mounting evidence suggests that prion-strain-specific features segregate with different PrPSc conformational and aggregation states. Strains are of practical relevance in prion diseases as they can drastically differ in many aspects, such as incubation period, PrPSc biochemical profile (e.g., electrophoretic mobility and glycoform ratio) and distribution of brain lesions. Importantly, such different features are maintained after inoculation of a prion strain into genetically identical hosts and are relatively stable across serial passages. This review focuses on the characterization of prion strains and on the wide range of important implications that the study of prion strains involves. PMID:23357828

Mitigation of Prion Infectivity and Conversion Capacity by a Simulated Natural Process—Repeated Cycles of Drying and Wetting

Science.gov (United States)

Yuan, Qi; Eckland, Thomas; Telling, Glenn; Bartz, Jason; Bartelt-Hunt, Shannon

2015-01-01

Prions enter the environment from infected hosts, bind to a wide range of soil and soil minerals, and remain highly infectious. Environmental sources of prions almost certainly contribute to the transmission of chronic wasting disease in cervids and scrapie in sheep and goats. While much is known about the introduction of prions into the environment and their interaction with soil, relatively little is known about prion degradation and inactivation by natural environmental processes. In this study, we examined the effect of repeated cycles of drying and wetting on prion fitness and determined that 10 cycles of repeated drying and wetting could reduce PrPSc abundance, PMCA amplification efficiency and extend the incubation period of disease. Importantly, prions bound to soil were more susceptible to inactivation by repeated cycles of drying and wetting compared to unbound prions, a result which may be due to conformational changes in soil-bound PrPSc or consolidation of the bonding between PrPSc and soil. This novel finding demonstrates that naturally-occurring environmental process can degrade prions. PMID:25665187

Grass plants bind, retain, uptake, and transport infectious prions.

Science.gov (United States)

Pritzkow, Sandra; Morales, Rodrigo; Moda, Fabio; Khan, Uffaf; Telling, Glenn C; Hoover, Edward; Soto, Claudio

2015-05-26

Prions are the protein-based infectious agents responsible for prion diseases. Environmental prion contamination has been implicated in disease transmission. Here, we analyzed the binding and retention of infectious prion protein (PrP(Sc)) to plants. Small quantities of PrP(Sc) contained in diluted brain homogenate or in excretory materials (urine and feces) can bind to wheat grass roots and leaves. Wild-type hamsters were efficiently infected by ingestion of prion-contaminated plants. The prion-plant interaction occurs with prions from diverse origins, including chronic wasting disease. Furthermore, leaves contaminated by spraying with a prion-containing preparation retained PrP(Sc) for several weeks in the living plant. Finally, plants can uptake prions from contaminated soil and transport them to aerial parts of the plant (stem and leaves). These findings demonstrate that plants can efficiently bind infectious prions and act as carriers of infectivity, suggesting a possible role of environmental prion contamination in the horizontal transmission of the disease. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

End-to-end process of hollow spacecraft structures with high frequency and low mass obtained with in-house structural optimization tool and additive manufacturing

Directory of Open Access Journals (Sweden)

Alexandru-Mihai CISMILIANU

2017-09-01

Full Text Available In the space sector the most decisive elements are: mass reduction, cost saving and minimum lead time; here, structural optimization and additive layer manufacturing (ALM fit best. The design must be driven by stiffness, because an important requirement for spacecraft (S/C structures is to reduce the dynamic coupling between the S/C and the launch vehicle. The objective is to create an end-to-end process, from the input given by the customer to the manufacturing of an aluminum part as light as possible but at the same time considerably stiffer while taking the full advantage of the design flexibility given by ALM. To design and optimize the parts, a specialized in-house tool was used, guaranteeing a load-sufficient material distribution. Using topological optimization, the iterations between the design and the stress departments were diminished, thus greatly reducing the lead time. In order to improve and lighten the obtained structure a design with internal cavities and hollow beams was considered. This implied developing of a procedure for powder evacuation through iterations with the manufacturer while optimizing the design for ALM. The resulted part can be then manufactured via ALM with no need of further design adjustments. To achieve a high-quality part with maximum efficiency, it is essential to have a loop between the design team and the manufacturer. Topological optimization and ALM work hand in hand if used properly. The team achieved a more efficient structure using topology optimization and ALM, than using conventional design and manufacturing methods.

Syntheses, crystal structures and properties of novel copper(II) complexes obtained by reactions of copper(II) sulfate pentahydrate with tripodal ligands.

Science.gov (United States)

Zhao, Wei; Fan, Jian; Song, You; Kawaguchi, Hiroyuki; Okamura, Taka-aki; Sun, Wei-Yin; Ueyama, Norikazu

2005-04-21

Three novel metal-organic frameworks (MOFs), [Cu(1)SO4].H2O (4), [Cu2(2)2(SO4)2].4H2O (5) and [Cu(3)(H2O)]SO4.5.5H2O (6), were obtained by hydrothermal reactions of CuSO4.5H2O with the corresponding ligands, which have different flexibility. The structures of the synthesized complexes were determined by single-crystal X-ray diffraction analyses. Complex 4 has a 2D network structure with two types of metallacycles. Complex 5 also has a 2D network structure in which each independent 2D sheet contains two sub-layers bridged by oxygen atoms of the sulfate anions. Complex 6 has a 2D puckered structure in which the sulfate anions serve as counter anions, which are different from those in complexes 4 (terminators) and 5 (bridges). The different structures of complexes 4, 5 and 6 indicate that the nature of organic ligands affected the structures of the assemblies greatly. The magnetic behavior of complex 5 and anion-exchange properties of complex 6 were investigated.

Inherited prion disease A117V is not simply a proteinopathy but produces prions transmissible to transgenic mice expressing homologous prion protein.

Science.gov (United States)

Asante, Emmanuel A; Linehan, Jacqueline M; Smidak, Michelle; Tomlinson, Andrew; Grimshaw, Andrew; Jeelani, Asif; Jakubcova, Tatiana; Hamdan, Shyma; Powell, Caroline; Brandner, Sebastian; Wadsworth, Jonathan D F; Collinge, John

2013-01-01

Prions are infectious agents causing fatal neurodegenerative diseases of humans and animals. In humans, these have sporadic, acquired and inherited aetiologies. The inherited prion diseases are caused by one of over 30 coding mutations in the human prion protein (PrP) gene (PRNP) and many of these generate infectious prions as evidenced by their experimental transmissibility by inoculation to laboratory animals. However, some, and in particular an extensively studied type of Gerstmann-Sträussler-Scheinker syndrome (GSS) caused by a PRNP A117V mutation, are thought not to generate infectious prions and instead constitute prion proteinopathies with a quite distinct pathogenetic mechanism. Multiple attempts to transmit A117V GSS have been unsuccessful and typical protease-resistant PrP (PrP(Sc)), pathognomonic of prion disease, is not detected in brain. Pathogenesis is instead attributed to production of an aberrant topological form of PrP, C-terminal transmembrane PrP ((Ctm)PrP). Barriers to transmission of prion strains from one species to another appear to relate to structural compatibility of PrP in host and inoculum and we have therefore produced transgenic mice expressing human 117V PrP. We found that brain tissue from GSS A117V patients did transmit disease to these mice and both the neuropathological features of prion disease and presence of PrP(Sc) was demonstrated in the brains of recipient transgenic mice. This PrP(Sc) rapidly degraded during laboratory analysis, suggesting that the difficulty in its detection in patients with GSS A117V could relate to post-mortem proteolysis. We conclude that GSS A117V is indeed a prion disease although the relative contributions of (Ctm)PrP and prion propagation in neurodegeneration and their pathogenetic interaction remains to be established.

Inherited prion disease A117V is not simply a proteinopathy but produces prions transmissible to transgenic mice expressing homologous prion protein.

Directory of Open Access Journals (Sweden)

Emmanuel A Asante

Full Text Available Prions are infectious agents causing fatal neurodegenerative diseases of humans and animals. In humans, these have sporadic, acquired and inherited aetiologies. The inherited prion diseases are caused by one of over 30 coding mutations in the human prion protein (PrP gene (PRNP and many of these generate infectious prions as evidenced by their experimental transmissibility by inoculation to laboratory animals. However, some, and in particular an extensively studied type of Gerstmann-Sträussler-Scheinker syndrome (GSS caused by a PRNP A117V mutation, are thought not to generate infectious prions and instead constitute prion proteinopathies with a quite distinct pathogenetic mechanism. Multiple attempts to transmit A117V GSS have been unsuccessful and typical protease-resistant PrP (PrP(Sc, pathognomonic of prion disease, is not detected in brain. Pathogenesis is instead attributed to production of an aberrant topological form of PrP, C-terminal transmembrane PrP ((CtmPrP. Barriers to transmission of prion strains from one species to another appear to relate to structural compatibility of PrP in host and inoculum and we have therefore produced transgenic mice expressing human 117V PrP. We found that brain tissue from GSS A117V patients did transmit disease to these mice and both the neuropathological features of prion disease and presence of PrP(Sc was demonstrated in the brains of recipient transgenic mice. This PrP(Sc rapidly degraded during laboratory analysis, suggesting that the difficulty in its detection in patients with GSS A117V could relate to post-mortem proteolysis. We conclude that GSS A117V is indeed a prion disease although the relative contributions of (CtmPrP and prion propagation in neurodegeneration and their pathogenetic interaction remains to be established.

Superficial characterization and nano structural of nano multilayers Cr/Cr N obtained by UBM with different unbalance grades

International Nuclear Information System (INIS)

Piratoba, U.; Arenas A, J.; Olaya, J. J.

2013-01-01

Coatings of 25 bilayers of Cr/Cr N, with total thickness between 1.32 and 1.67 microns, were deposited by reactive sputtering on silicon and H13 steel, in argon and argon with nitrogen atmospheres. A power of 160 watts, flows of argon and nitrogen of 9 and 3 sc cm respectively, and an axial unbalanced magnetron, whose coefficient of geometrical unbalance K G was varied between 0.85 and 1.37. Of these coatings, micrographs of surface and cross section scanning electron microscopy were obtained, was make a micro structural characterization with X-ray diffraction, a nano structural characterization by transmission electron microscopy, and surface characterization by atomic force microscopy in tapping mode: analysis showed uniform surface coating with globular and pyramidal formations, which contain some granular inclusions and microscopic craters. With the increase in the unbalance of the magnetic field, the grain size, the roughness and the speed of the coatings growth were increased. (Author)

Polymerization of allyl alcohol by radiation to obtain microencapsulated structure

International Nuclear Information System (INIS)

Usanmaz, A.; Saricilar, S.

1989-01-01

Allyl alcohol was polymerized by radiation under various conditions. The limiting conversions were about 30 % in bulk, 35 % when containing 0.03 mole fraction AlCl 3 and 50 % when water was contained at 27 % (v/v). Irradiation was done with Co-60 gamma rays at room temperature and under vacuum. The presence of oxygen did not cause any change in the reaction rate. Molecular weights were determined by viscosity and cryoscopic methods. K and α values were found to be 3.57 x 10 -4 and 0.62 for solutions in methanol at 25degC. The polymers up to about 10 % conversion were viscous liquids having microcapsular structures: at high conversions, they became hard and glassy. The microencapsulated structures were also retained in solutions in methanol, acetone, and isopropyl alcohol. The samples were insoluble in water, benzene, and toluence. (author)

Use of bovine recombinant prion protein and real-time quaking-induced conversion to detect cattle transmissible mink encephalopathy prions and discriminate classical and atypical L- and H-Type bovine spongiform encephalopathy.

Science.gov (United States)

Hwang, Soyoun; Greenlee, Justin J; Nicholson, Eric M

2017-01-01

Prions are amyloid-forming proteins that cause transmissible spongiform encephalopathies through a process involving conversion from the normal cellular prion protein to the pathogenic misfolded conformation (PrPSc). This conversion has been used for in vitro assays including serial protein misfolding amplification and real-time quaking induced conversion (RT-QuIC). RT-QuIC can be used for the detection of prions in a variety of biological tissues from humans and animals. Extensive work has been done to demonstrate that RT-QuIC is a rapid, specific, and highly sensitive prion detection assay. RT-QuIC uses recombinant prion protein to detect minute amounts of PrPSc. RT-QuIC has been successfully used to detect PrPSc from different prion diseases with a variety of substrates including hamster, human, sheep, bank vole, bovine and chimeric forms of prion protein. However, recombinant bovine prion protein has not been used to detect transmissible mink encephalopathy (TME) or to differentiate types of bovine spongiform encephalopathy (BSE) in samples from cattle. We evaluated whether PrPSc from TME and BSE infected cattle can be detected with RT-QuIC using recombinant bovine prion proteins, and optimized the reaction conditions to specifically detect cattle TME and to discriminate between classical and atypical BSE by conversion efficiency. We also found that substrate composed of the disease associated E211K mutant protein can be effective for the detection of TME in cattle and that wild type prion protein appears to be a practical substrate to discriminate between the different types of BSEs.

PrP(Sc-specific antibodies with the ability to immunodetect prion oligomers.

Directory of Open Access Journals (Sweden)

Mourad Tayebi

Full Text Available The development of antibodies with binding capacity towards soluble oligomeric forms of PrPSc recognised in the aggregation process in early stage of the disease would be of paramount importance in diagnosing prion diseases before extensive neuropathology has ensued. As blood transfusion appears to be efficient in the transmission of the infectious prion agent, there is an urgent need to develop reagents that would specifically recognize oligomeric forms of the abnormally folded prion protein, PrPSc.To that end, we show that anti-PrP monoclonal antibodies (called PRIOC mAbs derived from mice immunised with native PrP-coated microbeads are able to immunodetect oligomers/multimers of PrPSc. Oligomer-specific immunoreactivity displayed by these PRIOC mAbs was demonstrated as large aggregates of immunoreactive deposits in prion-permissive neuroblastoma cell lines but not in equivalent non-infected or prn-p(0/0 cell lines. In contrast, an anti-monomer PrP antibody displayed diffuse immunoreactivity restricted to the cell membrane. Furthermore, our PRIOC mAbs did not display any binding with monomeric recombinant and cellular prion proteins but strongly detected PrPSc oligomers as shown by a newly developed sensitive and specific ELISA. Finally, PrioC antibodies were also able to bind soluble oligomers formed of Aβ and α-synuclein. These findings demonstrate the potential use of anti-prion antibodies that bind PrPSc oligomers, recognised in early stage of the disease, for the diagnosis of prion diseases in blood and other body fluids.

The characteristics of polysaccharides fractions of sunflower obtained in dynamic mode

International Nuclear Information System (INIS)

Makhkamov, Kh.K.; Gorshkova, R.M.; Khalikova, S.

2013-01-01

Present article describes characteristics of polysaccharides fractions of sunflower obtained in dynamic mode. The decomposition of sunflower pectin was studied by means of continuous fractionation method in dynamic regime. It was found that the process is of extreme nature due to heterogeneity of its macromolecule structure. The additional information on macromolecule structure of sunflower pectin was obtained.

Analysis shear wave velocity structure obtained from surface wave methods in Bornova, Izmir

Energy Technology Data Exchange (ETDEWEB)

Pamuk, Eren, E-mail: eren.pamuk@deu.edu.tr; Akgün, Mustafa, E-mail: mustafa.akgun@deu.edu.tr [Department of Geophysical Engineering, Dokuz Eylul University, Izmir (Turkey); Özdağ, Özkan Cevdet, E-mail: cevdet.ozdag@deu.edu.tr [Dokuz Eylul University Rectorate, Izmir (Turkey)

2016-04-18

Properties of the soil from the bedrock is necessary to describe accurately and reliably for the reduction of earthquake damage. Because seismic waves change their amplitude and frequency content owing to acoustic impedance difference between soil and bedrock. Firstly, shear wave velocity and depth information of layers on bedrock is needed to detect this changing. Shear wave velocity can be obtained using inversion of Rayleigh wave dispersion curves obtained from surface wave methods (MASW- the Multichannel Analysis of Surface Waves, ReMi-Refraction Microtremor, SPAC-Spatial Autocorrelation). While research depth is limeted in active source study, a passive source methods are utilized for deep depth which is not reached using active source methods. ReMi method is used to determine layer thickness and velocity up to 100 m using seismic refraction measurement systems.The research carried out up to desired depth depending on radius using SPAC which is utilized easily in conditions that district using of seismic studies in the city. Vs profiles which are required to calculate deformations in under static and dynamic loads can be obtained with high resolution using combining rayleigh wave dispersion curve obtained from active and passive source methods. In the this study, Surface waves data were collected using the measurements of MASW, ReMi and SPAC at the İzmir Bornova region. Dispersion curves obtained from surface wave methods were combined in wide frequency band and Vs-depth profiles were obtained using inversion. Reliability of the resulting soil profiles were provided by comparison with theoretical transfer function obtained from soil paremeters and observed soil transfer function from Nakamura technique and by examination of fitting between these functions. Vs values are changed between 200-830 m/s and engineering bedrock (Vs>760 m/s) depth is approximately 150 m.

Carbon nanofibers obtained from electrospinning process

Science.gov (United States)

Bovi de Oliveira, Juliana; Müller Guerrini, Lília; Sizuka Oishi, Silvia; Rogerio de Oliveira Hein, Luis; dos Santos Conejo, Luíza; Cerqueira Rezende, Mirabel; Cocchieri Botelho, Edson

2018-02-01

In recent years, reinforcements consisting of carbon nanostructures, such as carbon nanotubes, fullerenes, graphenes, and carbon nanofibers have received significant attention due mainly to their chemical inertness and good mechanical, electrical and thermal properties. Since carbon nanofibers comprise a continuous reinforcing with high specific surface area, associated with the fact that they can be obtained at a low cost and in a large amount, they have shown to be advantageous compared to traditional carbon nanotubes. The main objective of this work is the processing of carbon nanofibers, using polyacrylonitrile (PAN) as a precursor, obtained by the electrospinning process via polymer solution, with subsequent use for airspace applications as reinforcement in polymer composites. In this work, firstly PAN nanofibers were produced by electrospinning with diameters in the range of (375 ± 85) nm, using a dimethylformamide solution. Using a furnace, the PAN nanofiber was converted into carbon nanofiber. Morphologies and structures of PAN and carbon nanofibers were investigated by scanning electron microscopy, Raman Spectroscopy, thermogravimetric analyses and differential scanning calorimeter. The resulting residual weight after carbonization was approximately 38% in weight, with a diameters reduction of 50%, and the same showed a carbon yield of 25%. From the analysis of the crystalline structure of the carbonized material, it was found that the material presented a disordered structure.

The structure and mechanical properties of multilayer nanocrystalline TiN/ZrN coatings obtained by vacuum-arc deposition

Directory of Open Access Journals (Sweden)

A.V. Demchyshyn

2007-12-01

Full Text Available TiN/ZrN multilayered condensates on BK-8 carbide tips substrates (62 HRC were produced by the vacuumarc deposition technique, using Ti and Zr plasma flows in reactive nitrogen gas medium with working pressure of 6.6·10–1 Pa. The TiN/ZrN multilayered condensates consist of TiN and ZrN sublayers, which have a thickness of ~100 nm, controlled by the processing parameters of the used deposition technique. The obtained coatings have hardness of 45 GPa and Young’s modulus of 320 GPa. The obtained results show that mechanical properties of such multilayered composites are considerably improved in comparison to those for the single-component coatings, TiN and ZrN. The dependence of hardness and Young’s modulus of the composites on sublayer thickness within a range of 100 nm was determined. The investigated structure and improved mechanical properties of the TiN/ZrN multilayered condensates would be very good platform for finding their industrial application, such as hard coatings with different purposes.

Sheet-like carbon particles with graphene structures obtained from a Bunsen flame

DEFF Research Database (Denmark)

Ossler, Frederik; Wagner, Jakob Birkedal; Canton, Sophie E.

2010-01-01

for structural and elemental analysis. They were found to be several hundreds of nanometers in size. Such large structures are not easily explained from gas-phase kinetic models, yet the sheets occurred relatively frequent in the images. Some pictures also showed interesting polygonal few-layered graphitic...

Titania nanotube powders obtained by rapid breakdown anodization in perchloric acid electrolytes

International Nuclear Information System (INIS)

Ali, Saima; Hannula, Simo-Pekka

2017-01-01

Titania nanotube (TNT) powders are prepared by rapid break down anodization (RBA) in a 0.1 M perchloric acid (HClO 4 ) solution (Process 1), and ethylene glycol (EG) mixture with HClO 4 and water (Process 2). A study of the as-prepared and calcined TNT powders obtained by both processes is implemented to evaluate and compare the morphology, crystal structure, specific surface area, and the composition of the nanotubes. Longer TNTs are formed in Process 1, while comparatively larger pore diameter and wall thickness are obtained for the nanotubes prepared by Process 2. The TNTs obtained by Process 1 are converted to nanorods at 350 °C, while nanotubes obtained by Process 2 preserve tubular morphology till 350 °C. In addition, the TNTs prepared by an aqueous electrolyte have a crystalline structure, whereas the TNTs obtained by Process 2 are amorphous. Samples calcined till 450 °C have XRD peaks from the anatase phase, while the rutile phase appears at 550 °C for the TNTs prepared by both processes. The Raman spectra also show clear anatase peaks for all samples except the as-prepared sample obtained by Process 2, thus supporting the XRD findings. FTIR spectra reveal the presence of O-H groups in the structure for the TNTs obtained by both processes. However, the presence is less prominent for annealed samples. Additionally, TNTs obtained by Process 2 have a carbonaceous impurity present in the structure attributed to the electrolyte used in that process. While a negligible weight loss is typical for TNTs prepared from aqueous electrolytes, a weight loss of 38.6% in the temperature range of 25–600 °C is found for TNTs prepared in EG electrolyte (Process 2). A large specific surface area of 179.2 m 2 g −1 is obtained for TNTs prepared by Process 1, whereas Process 2 produces nanotubes with a lower specific surface area. The difference appears to correspond to the dimensions of the nanotubes obtained by the two processes. - Graphical abstract: Titania nanotube

INTERACTIVE GLOBAL NETWORK FOR WEATHER DATA OBTAINING, EXCHANGE AND DISSEMINATION

Directory of Open Access Journals (Sweden)

Ю.А. Авер’янова

2012-12-01

Full Text Available  The possibility to enhance the weather information provision of relevant customers is considered. It is based on the use of the complex global system for weather information obtaining, exchange and dissemination. The structural diagram of the system is proposed. The structural diagram is completed with addition connections that allow to pay strong attention on the most dangerous meteorological phenomena at the critical moment of flight. The proposed approach gives possibility to aircraft crew to select and use specified operative information and increase the probability for proper decision taking. The aircraft are used as the dynamic elements for data obtaining and exchange in the frame of the global system for weather information obtaining, exchange and dissemination.

Geopolymer obtained from coal ash

International Nuclear Information System (INIS)

Conte, V.; Bissari, E.S.; Uggioni, E.; Bernardin, A.M.

2011-01-01

Geopolymers are three-dimensional alumino silicates that can be rapidly formed at low temperature from naturally occurring aluminosilicates with a structure similar to zeolites. In this work coal ash (Tractebel Energy) was used as source of aluminosilicate according a full factorial design in eight formulations with three factors (hydroxide type and concentration and temperature) and two-levels. The ash was dried and hydroxide was added according type and concentration. The geopolymer was poured into cylindrical molds, cured (14 days) and subjected to compression test. The coal ash from power plants belongs to the Si-Al system and thus can easily form geopolymers. The compression tests showed that it is possible to obtain samples with strength comparable to conventional Portland cement. As a result, temperature and molarity are the main factors affecting the compressive strength of the obtained geopolymer. (author)

Evidence of scrapie transmission to sheep via goat milk.

Science.gov (United States)

Konold, Timm; Thorne, Leigh; Simmons, Hugh A; Hawkins, Steve A C; Simmons, Marion M; González, Lorenzo

2016-09-17

Previous studies confirmed that classical scrapie can be transmitted via milk in sheep. The current study aimed to investigate whether scrapie can also be transmitted via goat milk using in vivo (new-born lambs fed milk from scrapie-affected goats due to the unavailability of goat kids from guaranteed scrapie-free herds) and in vitro methods (serial protein misfolding cyclic amplification [sPMCA] on milk samples). In an initial pilot study, new-born lambs of two different prion protein gene (PRNP) genotypes (six VRQ/VRQ and five ARQ/ARQ) were orally challenged with 5 g brain homogenate from two scrapie-affected goats to determine susceptibility of sheep to goat scrapie. All sheep challenged with goat scrapie brain became infected based on the immunohistochemical detection of disease-associated PrP (PrP(sc)) in lymphoid tissue, with an ARQ/ARQ sheep being the first to succumb. Subsequent feeding of milk to eight pairs of new-born ARQ/ARQ lambs, with each pair receiving milk from a different scrapie-affected goat, resulted in scrapie in the six pairs that received the largest volume of milk (38-87 litres per lamb), whereas two pairs fed 8-9 litres per lamb, and an environmental control group raised on sheep milk from healthy ewes, did not show evidence of infection when culled at up to 1882 days of age. Infection in those 12 milk recipients occurred regardless of the clinical status, PrP(sc) distribution, caprine arthritis-encephalitis virus infection status and PRNP polymorphisms at codon 142 (II or IM) of the donor goats, but survival time was influenced by PRNP polymorphisms at codon 141. Serial PMCA applied to a total of 32 milk samples (four each from the eight donor goats collected throughout lactation) detected PrP(sc) in one sample each from two goats. The scrapie agent was present in the milk from infected goats and was able to transmit to susceptible species even at early preclinical stage of infection, when PrP(sc) was undetectable in the brain of the

Prion Propagation in Cells Expressing PrP Glycosylation Mutants ▿

Science.gov (United States)

Salamat, Muhammad K.; Dron, Michel; Chapuis, Jérôme; Langevin, Christelle; Laude, Hubert

2011-01-01

Infection by prions involves conversion of a host-encoded cell surface protein (PrPC) to a disease-related isoform (PrPSc). PrPC carries two glycosylation sites variably occupied by complex N-glycans, which have been suggested by previous studies to influence the susceptibility to these diseases and to determine characteristics of prion strains. We used the Rov cell system, which is susceptible to sheep prions, to generate a series of PrPC glycosylation mutants with mutations at one or both attachment sites. We examined their subcellular trafficking and ability to convert into PrPSc and to sustain stable prion propagation in the absence of wild-type PrP. The susceptibility to infection of mutants monoglycosylated at either site differed dramatically depending on the amino acid substitution. Aglycosylated double mutants showed overaccumulation in the Golgi compartment and failed to be infected. Introduction of an ectopic glycosylation site near the N terminus fully restored cell surface expression of PrP but not convertibility into PrPSc, while PrPC with three glycosylation sites conferred cell permissiveness to infection similarly to the wild type. In contrast, predominantly aglycosylated molecules with nonmutated N-glycosylation sequons, produced in cells expressing glycosylphosphatidylinositol-anchorless PrPC, were able to form infectious PrPSc. Together our findings suggest that glycosylation is important for efficient trafficking of anchored PrP to the cell surface and sustained prion propagation. However, properly trafficked glycosylation mutants were not necessarily prone to conversion, thus making it difficult in such studies to discern whether the amino acid changes or glycan chain removal most influences the permissiveness to prion infection. PMID:21248032

Prion propagation in cells expressing PrP glycosylation mutants.

Science.gov (United States)

Salamat, Muhammad K; Dron, Michel; Chapuis, Jérôme; Langevin, Christelle; Laude, Hubert

2011-04-01

Infection by prions involves conversion of a host-encoded cell surface protein (PrP(C)) to a disease-related isoform (PrP(Sc)). PrP(C) carries two glycosylation sites variably occupied by complex N-glycans, which have been suggested by previous studies to influence the susceptibility to these diseases and to determine characteristics of prion strains. We used the Rov cell system, which is susceptible to sheep prions, to generate a series of PrP(C) glycosylation mutants with mutations at one or both attachment sites. We examined their subcellular trafficking and ability to convert into PrP(Sc) and to sustain stable prion propagation in the absence of wild-type PrP. The susceptibility to infection of mutants monoglycosylated at either site differed dramatically depending on the amino acid substitution. Aglycosylated double mutants showed overaccumulation in the Golgi compartment and failed to be infected. Introduction of an ectopic glycosylation site near the N terminus fully restored cell surface expression of PrP but not convertibility into PrP(Sc), while PrP(C) with three glycosylation sites conferred cell permissiveness to infection similarly to the wild type. In contrast, predominantly aglycosylated molecules with nonmutated N-glycosylation sequons, produced in cells expressing glycosylphosphatidylinositol-anchorless PrP(C), were able to form infectious PrP(Sc). Together our findings suggest that glycosylation is important for efficient trafficking of anchored PrP to the cell surface and sustained prion propagation. However, properly trafficked glycosylation mutants were not necessarily prone to conversion, thus making it difficult in such studies to discern whether the amino acid changes or glycan chain removal most influences the permissiveness to prion infection.

Glypican-1 mediates both prion protein lipid raft association and disease isoform formation.

Directory of Open Access Journals (Sweden)

David R Taylor

2009-11-01

Full Text Available In prion diseases, the cellular form of the prion protein, PrP(C, undergoes a conformational conversion to the infectious isoform, PrP(Sc. PrP(C associates with lipid rafts through its glycosyl-phosphatidylinositol (GPI anchor and a region in its N-terminal domain which also binds to heparan sulfate proteoglycans (HSPGs. We show that heparin displaces PrP(C from rafts and promotes its endocytosis, suggesting that heparin competes with an endogenous raft-resident HSPG for binding to PrP(C. We then utilised a transmembrane-anchored form of PrP (PrP-TM, which is targeted to rafts solely by its N-terminal domain, to show that both heparin and phosphatidylinositol-specific phospholipase C can inhibit its association with detergent-resistant rafts, implying that a GPI-anchored HSPG targets PrP(C to rafts. Depletion of the major neuronal GPI-anchored HSPG, glypican-1, significantly reduced the raft association of PrP-TM and displaced PrP(C from rafts, promoting its endocytosis. Glypican-1 and PrP(C colocalised on the cell surface and both PrP(C and PrP(Sc co-immunoprecipitated with glypican-1. Critically, treatment of scrapie-infected N2a cells with glypican-1 siRNA significantly reduced PrP(Sc formation. In contrast, depletion of glypican-1 did not alter the inhibitory effect of PrP(C on the beta-secretase cleavage of the Alzheimer's amyloid precursor protein. These data indicate that glypican-1 is a novel cellular cofactor for prion conversion and we propose that it acts as a scaffold facilitating the interaction of PrP(C and PrP(Sc in lipid rafts.

Effects of heme-PrP complex on cell-free conversion and peroxidase-linked immunodetection of prions in blood-based assays.

Science.gov (United States)

Soutyrine, Andrei; Yogasingam, Nishandan; Huang, Hongsheng; Mitchell, Gordon

2015-08-01

Prion protein (PrP) binding to natural and synthetic porphyrins has been previously demonstrated but the effects of endogenous heme interactions with PrP remain uncertain. This study investigated implications of this interaction in blood-based peroxidase-linked prion immunodetection and seeded conversion of cellular prion (PrP(C)) into disease associated form (PrP(Sc)). Heme binding to recombinant PrP(C) enhanced intrinsic peroxidase activity (POD) by 2.5-fold and POD inherent to denatured blood accounted for over 84% of luminol-based substrate oxidation in a prion immunodetection assay. An immuno-capture assay showed that 75-98% of blood POD was attributable to binding of PrP(C) with endogenous heme. Additionally, 10 μM heme inhibited (PPrP(C) to PrP(Sc) through the protein misfolding cycling amplification assay. We conclude that the observed effects can interfere with cell-free conversion and peroxidase-linked immunodetection of prions in blood-based assays. These results indicate that heme-PrP interactions could modulate intrinsic POD and protect PrP(C) from conversion into PrP(Sc). Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Peripheral Tissue Involvement in Sporadic, Iatrogenic, and Variant Creutzfeldt-Jakob Disease

Science.gov (United States)

Head, Mark W.; Ritchie, Diane; Smith, Nadine; McLoughlin, Victoria; Nailon, William; Samad, Sazia; Masson, Stephen; Bishop, Matthew; McCardle, Linda; Ironside, James W.

2004-01-01

Human prion diseases are rare fatal neurodegenerative conditions that occur as acquired, familial, or idiopathic disorders. A key event in their pathogenesis is the accumulation of an altered form of the prion protein, termed PrPSc, in the central nervous system. A novel acquired human prion disease, variant Creutzfeldt-Jakob disease, is thought to result from oral exposure to the bovine spongiform encephalopathy agent. This disease differs from other human prion diseases in its neurological, neuropathological, and biochemical phenotype. We have used immunohistochemistry and Western blot techniques to analyze the tissue distribution and biochemical properties of PrPSc in peripheral tissues in a unique series of nine cases of variant Creutzfeldt-Jakob disease. We have compared this with the distribution and biochemical forms found in all of the major subtypes of sporadic Creutzfeldt-Jakob disease and in a case of iatrogenic Creutzfeldt-Jakob disease associated with growth hormone therapy. The results show that involvement of the lymphoreticular system is a defining feature of variant Creutzfeldt-Jakob disease, but that the biochemical isoform of PrPSc found is influenced by the cell type in which it accumulates. PMID:14695328

Titania nanotube powders obtained by rapid breakdown anodization in perchloric acid electrolytes

Energy Technology Data Exchange (ETDEWEB)

Ali, Saima, E-mail: saima.ali@aalto.fi; Hannula, Simo-Pekka

2017-05-15

Titania nanotube (TNT) powders are prepared by rapid break down anodization (RBA) in a 0.1 M perchloric acid (HClO{sub 4}) solution (Process 1), and ethylene glycol (EG) mixture with HClO{sub 4} and water (Process 2). A study of the as-prepared and calcined TNT powders obtained by both processes is implemented to evaluate and compare the morphology, crystal structure, specific surface area, and the composition of the nanotubes. Longer TNTs are formed in Process 1, while comparatively larger pore diameter and wall thickness are obtained for the nanotubes prepared by Process 2. The TNTs obtained by Process 1 are converted to nanorods at 350 °C, while nanotubes obtained by Process 2 preserve tubular morphology till 350 °C. In addition, the TNTs prepared by an aqueous electrolyte have a crystalline structure, whereas the TNTs obtained by Process 2 are amorphous. Samples calcined till 450 °C have XRD peaks from the anatase phase, while the rutile phase appears at 550 °C for the TNTs prepared by both processes. The Raman spectra also show clear anatase peaks for all samples except the as-prepared sample obtained by Process 2, thus supporting the XRD findings. FTIR spectra reveal the presence of O-H groups in the structure for the TNTs obtained by both processes. However, the presence is less prominent for annealed samples. Additionally, TNTs obtained by Process 2 have a carbonaceous impurity present in the structure attributed to the electrolyte used in that process. While a negligible weight loss is typical for TNTs prepared from aqueous electrolytes, a weight loss of 38.6% in the temperature range of 25–600 °C is found for TNTs prepared in EG electrolyte (Process 2). A large specific surface area of 179.2 m{sup 2} g{sup −1} is obtained for TNTs prepared by Process 1, whereas Process 2 produces nanotubes with a lower specific surface area. The difference appears to correspond to the dimensions of the nanotubes obtained by the two processes. - Graphical abstract

A new numerical method for inverse Laplace transforms used to obtain gluon distributions from the proton structure function

International Nuclear Information System (INIS)

Block, Martin M.; Durand, Loyal

2011-01-01

We recently derived a very accurate and fast new algorithm for numerically inverting the Laplace transforms needed to obtain gluon distributions from the proton structure function F 2 γp (x,Q 2 ). We numerically inverted the function g(s), s being the variable in Laplace space, to G(v), where v is the variable in ordinary space. We have since discovered that the algorithm does not work if g(s)→0 less rapidly than 1/s as s→∞, e.g., as 1/s β for 0 β-1 and a polynomial in v. We test the algorithm numerically for very small positive β, β=10 -6 obtaining numerical results that imitate the Dirac delta function δ(v). We also devolve the published MSTW2008LO gluon distribution at virtuality Q 2 =5 GeV 2 down to the lower virtuality Q 2 =1.69 GeV 2 . For devolution, β is negative, giving rise to inverse Laplace transforms that are distributions and not proper functions. This requires us to introduce the concept of Hadamard Finite Part integrals, which we discuss in detail. (orig.)

Carbon nanostructures obtained by underwater arc discharge of graphite electrodes: Synthesis and characterization

International Nuclear Information System (INIS)

Darias Gonzalez, J. G.; Hernandez Tabare, L.; Herrera Palma, V.; Sierra Trujillo, J. S.; Desdin Garcia, L. F.; Codorniu Pujals, D.; Bermudez Martinez, A.; Arias de Fuentes, O.; Maury Toledo, A.

2015-01-01

In the present work, the application of the method of underwater arc discharge of graphite electrodes for obtaining several carbon nano structures is described. The analysis of the obtained products by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Raman spectroscopy, Atomic Force Microscopy (AFM) and X-Ray Diffraction (XRD) showed that the samples collected from the material floating on the water surface were composed mainly by polyhedral onion-like particles, while those taken from the precipitate were a mixture multi walled nano-tubes, onion-like particles and other graphitic structures. The main features of the obtained nano structures are discussed. (Author)

Synchrotron Topographic and Diffractometer Studies of Buried Layered Structures Obtained by Implantation with Swift Heavy Ions in Silicon Single Crystals

International Nuclear Information System (INIS)

Wierzchowski, W.; Wieteska, K.; Zymierska, D.; Graeff, W.; Czosnyka, T.; Choinski, J.

2006-01-01

A distribution of crystallographic defects and deformation in silicon crystals subjected to deep implantation (20-50 μm) with ions of the energy of a few MeV/amu is studied. Three different buried layered structures (single layer, binary buried structure and triple buried structure) were obtained by implantation of silicon single crystals with 184 MeV argon ions, 29.7 MeV boron ions, and 140 MeV argon ions, each implantation at a fluency of 1x10 14 ions cm -2 . The implanted samples were examined by means of white beam X-ray section and projection topography, monochromatic beam topography and by recording local rocking curves with the beam restricted to 50 x 50 μm 2 . The experiment pointed to a very low level of implantation-induced strain (below 10 -5 ). The white beam Bragg case section experiment revealed a layer producing district black contrast located at a depth of the expected mean ion range. The presence of these buried layered structures in studied silicon crystals strongly affected the fringe pattern caused by curvature of the samples. In case of white beam projection and monochromatic beam topographs the implanted areas were revealed as darker regions with a very tiny grain like structure. One may interpret these results as the effect of considerable heating causing annihilation of point defects and formation of dislocation loops connected with point defect clusters. (author)

A Systematic Approach for Obtaining Performance on Matrix-Like Operations

Science.gov (United States)

Veras, Richard Michael

Scientific Computation provides a critical role in the scientific process because it allows us ask complex queries and test predictions that would otherwise be unfeasible to perform experimentally. Because of its power, Scientific Computing has helped drive advances in many fields ranging from Engineering and Physics to Biology and Sociology to Economics and Drug Development and even to Machine Learning and Artificial Intelligence. Common among these domains is the desire for timely computational results, thus a considerable amount of human expert effort is spent towards obtaining performance for these scientific codes. However, this is no easy task because each of these domains present their own unique set of challenges to software developers, such as domain specific operations, structurally complex data and ever-growing datasets. Compounding these problems are the myriads of constantly changing, complex and unique hardware platforms that an expert must target. Unfortunately, an expert is typically forced to reproduce their effort across multiple problem domains and hardware platforms. In this thesis, we demonstrate the automatic generation of expert level high-performance scientific codes for Dense Linear Algebra (DLA), Structured Mesh (Stencil), Sparse Linear Algebra and Graph Analytic. In particular, this thesis seeks to address the issue of obtaining performance on many complex platforms for a certain class of matrix-like operations that span across many scientific, engineering and social fields. We do this by automating a method used for obtaining high performance in DLA and extending it to structured, sparse and scale-free domains. We argue that it is through the use of the underlying structure found in the data from these domains that enables this process. Thus, obtaining performance for most operations does not occur in isolation of the data being operated on, but instead depends significantly on the structure of the data.

Investigation of the hyperfine properties of deoxy hemoglobin based on its electronic structure obtained by Hartree-Fock-Roothan procedure

Energy Technology Data Exchange (ETDEWEB)

Lata, K. Ramani [State University of New York at Albany, Department of Physics (United States); Sahoo, N. [University of Texas M.D. Anderson Cancer Center, Department of Radiation Physics (United States); Dubey, Archana [University of Central Florida, Department of Physics (United States); Scheicher, R. H. [Uppsala University, Condensed Matter Theory Group, Department of Physics and Materials Science (Sweden); Badu, S. R.; Pink, R. H.; Mahato, Dip N. [State University of New York at Albany, Department of Physics (United States); Schulte, A. F.; Saha, H. P. [University of Central Florida, Department of Physics (United States); Maharjan, N. B. [State University of New York at Albany, Department of Physics (United States); Chow, Lee [University of Central Florida, Department of Physics (United States); Das, T. P., E-mail: tpd56@albany.edu [State University of New York at Albany, Department of Physics (United States)

2008-01-15

The electronic structure of the heme unit of deoxyhemoglobin including the proximal imidazole has been studied using the first-principles Hartree-Fock procedure. Our results for the {sup 57m}Fe isomer shift and asymmetry parameter are in very good agreement with the values obtained from Moessbauer spectroscopy measurements. The {sup 57m}Fe nuclear quadrupole coupling constant is smaller than the experimental result and possible ways to improve the agreement in the future are discussed. Improved analysis of the Moessbauer data, removing some approximations made for deriving the magnetic hyperfine tensor for the {sup 57m}Fe nucleus, is suggested to allow quantitative comparison with our results in the future.

Structure and magnetic properties of Gd{sub x}Y{sub 1−x}FeO{sub 3} obtained by mechanosynthesis

Energy Technology Data Exchange (ETDEWEB)

Bolarín-Miró, A.M. [Área Académica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo Mineral de la Reforma, Hidalgo 42184 (Mexico); Sánchez-De Jesús, F., E-mail: fsanchez@uaeh.edu.mx [Área Académica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo Mineral de la Reforma, Hidalgo 42184 (Mexico); Cortés-Escobedo, C.A. [Centro de Investigación e Innovación Tecnológica del IPN, Distrito Federal 02250 (Mexico); Valenzuela, R. [Depto. de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico); Ammar, S. [ITODYS, UMR 7086, Université de Paris-Diderot, 75250 Paris Cedex (France)

2014-02-15

Highlights: • Orthohombic GDxY1-xFeO3 was obtained by mechanosynthesis after 5 h of milling. • Mechanosynthesized GdxY1-xFeO3 show weak ferromagnetic behavior. • Mechanosynthesis promotes unexpected magnetic properties in GdxY1-xFeO3. • The maximum magnetization that was reached 7.7 emu/g for Gdo.75Y0.25FeO3. • For Gd0.5Y0.5FeO3, the magnetization decreases down to 2.1 emu/g. -- Abstract: Solid solutions of yttrium–gadolinium orthoferrites Gd{sub x}Y{sub 1−x}FeO{sub 3} (0 ⩽ x ⩽ 1) were prepared by high-energy ball milling. The aim of this work was to study the influence of the synthesis parameters on the crystal structure and the magnetic behavior of these solid solutions. The precursors, Fe{sub 2}O{sub 3}, Y{sub 2}O{sub 3} and Gd{sub 2}O{sub 3}, mixed in a stoichiometric ratio to obtain these orthoferrites, were milled for different times (up to 5 h). X-ray diffraction and Rietveld refinement were used to elucidate the phase transformation as a function of the milling time. Results showed the complete formation of orthoferrite with an orthorhombic structure (S.G. Pbnm) without any annealing after 5 h of milling for all of the compositions. The effect of the synthesis process and the x value on the crystal structure and the magnetic properties were also studied. All of the synthesized powders demonstrated weak ferromagnetic behavior. In particular, an increase in the maximum magnetization for all the compositions was found, with a maximum that reached 7.7 emu/g for Gd{sub 0.75}Y{sub 0.25}FeO{sub 3}. For Gd{sub 0.5}Y{sub 0.5}FeO{sub 3}, the magnetization decreases down to 2.1 emu/g. A small contamination of metallic Fe was confirmed through electron spin resonance experiments.

Structural identification of lipopeptide biosurfactants produced by Bacillus subtilis strains grown on the media obtained from renewable natural resources.

Science.gov (United States)

Paraszkiewicz, Katarzyna; Bernat, Przemysław; Kuśmierska, Anna; Chojniak, Joanna; Płaza, Grażyna

2018-03-01

The aim of the study was to identify and characterize lipopeptide (LP) biosurfactants produced by two Bacillus subtilis strains (KP7 and I'-1a) grown on various media prepared from renewable natural resources: two different brewery wastewaters (BW#4 and BW#6), 2% beet molasses (M), apple peels extract (APE) supplemented with 0.25% of yeast extract (YE) or 0.25% peptone (P), and similarly supplemented carrot peels extract (CPE). In all used media both strains retained their individual LP production signature characterized by surfactin and iturin overproduction exhibited by KP7 and I'-1a strain, respectively. The production level and the structural diversity of synthesized LPs were dependent on the medium composition. In the CPE+YE medium it was higher than the yield obtained in Luria-Bertani (140.6 and 100.3 mg L -1 , respectively). Surfactins were produced by both strains as a mixture of four homologues (C13-C16) with the domination of variant C14. All other broths prepared from renewable resources strongly stimulated the iturin production by I'-1a strain with the exception of BW media. The highest iturin concentration (428.7 mg L -1 ) obtained in the CPE+P culture of I'-1a strain was about seven-fold higher than in LB. In all cultures only iturin A was identified. Among four iturin homologues (C13-16) produced by I'-1a strain, the highest relative contents of C16 variant (70-80%) were calculated for samples obtained from APE+P and CPE+P media. The obtained data indicate that the waste composition has an influence on both the types and amounts of biosurfactants produced by studied B. subtilis strains. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of the fine structure in the ionization plots obtained from a mass spectrometer with a large energy dispersion

International Nuclear Information System (INIS)

Deruaz, Daniel.

1974-01-01

The precise determination of ionization potentials, fragment ion appearance potentials and different excited state levels of the positive ions formed, together with phenomena due to an electron impact, were studied from ionization efficiency curves obtained by mass spectrometry. A standard ion source and an analytical method of electron energy dispersion reduction were used to study fine structures of ionization efficiency curves. Since the mass spectrometer was not adapted for the acquisition of ionization efficiency curve data an electronic system was designed to record these curves automatically. A precise stepwise potential variation of 45+-0.04mV was obtained, and for each step an intensity proportional to the number of ions created by the fragment considered, the additional gain being 4.4 and the linearity greater than 1% over a 13-volt region. Before each set of measurements the scattering was determined by calculation of the second derivative of a logistic function deduced from the cubic regression of the experimental helium function ionization efficiency curve values. The precision, given by the variance analysis SNEDECOR F test, is higher than 1/1000. For each series of recordings the numerical values were processed by a computer to raise by twenty the signal to noise ratio and calculate the ionization efficiency curve values by the energy difference method and the iterative unfolding method. In this way a high sensitivity was obtained for the determination of the curves near the ionization threshold, and a precision below 50MeV (at least equivalent to that given by ionization cells with quasi-monoenergetic electron beams) for the values of the ionization potentials, the appearance potentials and the excited state energy levels. In order to judge the reliability of the technique the ionization potentials of a set of eleven complex molecules were determined and compared with the results obtained by photoionization and photoelectron spectrometry [fr

Scrapie prion liposomes and rods exhibit target sizes of 55,000 Da

International Nuclear Information System (INIS)

Bellinger-Kawahara, C.G.; Kempner, E.; Groth, D.; Gabizon, R.; Prusiner, S.B.

1988-01-01

Scrapie is a degenerative neurologic disease in sheep and goats which can be experimentally transmitted to laboratory rodents. Considerable evidence suggests that the scrapie agent is composed largely, if not entirely, of an abnormal isoform of the prion protein (PrPSc). Inactivation of scrapie prions by ionizing radiation exhibited single-hit kinetics and gave a target size of 55,000 +/- 9000 mol wt. The inactivation profile was independent of the form of the prion. Scrapie agent infectivity in brain homogenates, microsomal fractions, detergent-extracted microsomes, purified amyloid rods, and liposomes exhibited the same inactivation profile. Our data are consistent with the hypothesis that the infectious particle causing scrapie contains approximately 2 PrPSc molecules

Correlation of MFOLD-predicted DNA secondary structures with separation patterns obtained by capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) analysis.

Science.gov (United States)

Glavac, Damjan; Potocnik, Uros; Podpecnik, Darja; Zizek, Teofil; Smerkolj, Sava; Ravnik-Glavac, Metka

2002-04-01

We have studied 57 different mutations within three beta-globin gene promoter fragments with sizes 52 bp, 77 bp, and 193 bp by fluorescent capillary electrophoresis CE-SSCP analysis. For each mutation and wild type, energetically most-favorable predicted secondary structures were calculated for sense and antisense strands using the MFOLD DNA-folding algorithm in order to investigate if any correlation exists between predicted DNA structures and actual CE migration time shifts. The overall CE-SSCP detection rate was 100% for all mutations in three studied DNA fragments. For shorter 52 bp and 77 bp DNA fragments we obtained a positive correlation between the migration time shifts and difference in free energy values of predicted secondary structures at all temperatures. For longer 193 bp beta-globin gene fragments with 46 mutations MFOLD predicted different secondary structures for 89% of mutated strands at 25 degrees C and 40 degrees C. However, the magnitude of the mobility shifts did not necessarily correlate with their secondary structures and free energy values except for the sense strand at 40 degrees C where this correlation was statistically significant (r = 0.312, p = 0.033). Results of this study provided more direct insight into the mechanism of CE-SSCP and showed that MFOLD prediction could be helpful in making decisions about the running temperatures and in prediction of CE-SSCP data patterns, especially for shorter (50-100 bp) DNA fragments. Copyright 2002 Wiley-Liss, Inc.

Obtaining the Wakefield Due to Cell-to-Cell Misalignments in a Linear Accelerator Structure

OpenAIRE

Bane, Karl L. F.; Li, Zenghai

2001-01-01

A linear accelerator structure, such as will be used in the linacs of the JLC/NLC collider, is composed of on the order of 100 cells. The cells are constructed as individual cups that are brazed together to form a structure. Fabrication error will result in slight cell-to-cell misalignments along the finished structure. In this report we derive an approximation to the transverse wakefield of a structure with cell-to-cell misalignments in terms of the eigenfunctions and eigenvalues of the erro...

The structure and physical-mechanical properties of the heat-resistant Ni-Co-Cr-Al-Y intermetallic coating obtained using rebuilt plasma equipment

Science.gov (United States)

Tarasenko, Yu. P.; Tsareva, I. N.; Berdnik, O. B.; Fel, Ya. A.; Kuzmin, V. I.; Mikhalchenko, A. A.; Kartaev, E. V.

2014-12-01

Results of a study of the structure, physico-mechanical properties, and the resistance to heat of Ni-Co-Cr-Al-Y intermetallic coatings obtained by powder spraying on the standard UPU-3D plasma spray facility (plasmatron with self-establishing arc length) and on the rebuilt facility equipped with the enhanced-power PNK-50 plasmatron with sectionalized inter-electrode insert, are reported. Coatings of higher density ( ρ = 7.9 g/cm3) and higher microhardness (H μ = 770 kg-force/mm2) with lower porosity values ( P = 5.7 %, P c = 5.1 %, and P 0 = 0.6 %) and high resistance to heat ((M - M0)/M0 = 1.2) were obtained. The developed coating is intended for protection of the working surfaces of turbine engine blades in gas-turbine power plants.

OBTAINING AND PROPERTIES OF AgInS2 FILMS

Directory of Open Access Journals (Sweden)

M. A. Abdullaev

2016-01-01

Full Text Available Aim. The aim is to obtain AgInS2 films and study their electrical and optical properties.Methods. The samples of thin AgInS2 films for measurement were obtained by the method of magnetron sputtering with direct current. The structure, phase and elemental composition were studied using DRON-2 X-ray diffractometer (СuKа - radiation and the microscope LEO-1450 with EDS attachment for X-ray microanalysis. The optical transmittance and absorption were examined using MDR-2 monochromator in the wavelength range of 400-800 nm with the Keitley electrometer and FD-10G; we applied the spectral resolution of ± 1 meV. The electrical conductivity, Hall effect was measured by the four-point probe method with indium ohmic contacts. Measurements were carried out in the temperature range of 77-400 K.Findings. We obtained indium disulfide and silver films with the thickness of up to 1 μm on quartz substrates by magnetron sputtering. It is shown that increasing the substrate temperature to about 450 0С allows to obtain single phase film with a chalcopyrite structure with a band gap of 1.88 eV and high absorption coefficient (>104см-1.Conclusions. The possibility of obtaining films in a wide range of the electrical resistance and variation of the electrical parameters at constant stoichiometry is of interest for efficient technologies of phototransduction.

Thermoelectric generator based on composites obtained by sintering of detonation nanodiamonds

Science.gov (United States)

Eidelman, E. D.; Meilakhs, A. P.; Semak, B. V.; Shakhov, F. M.

2017-11-01

A model of a thermoelectric generator is proposed, in which composite materials obtained by sintering diamond nanoparticles are used as the main component. To increase the useful conversion of heat into electric current, it is proposed to use the effect of electron drag by ballistic phonons. To reduce the ineffective heat spread, it is proposed to use the effect of thermal resistance of the boundaries between the graphite-like and diamond-like phases of the composite. An experimental confirmation of the existence of an optimal volume ratio between graphite-like and diamond-like phases of the composite is predicted and obtained. The highest achieved value of thermoelectric coefficient in the actual structure is 80 µV K-1 (which means 20 times increase compared to that of composites not of the optimal structure), with a thermal conductivity of 50 W m-1 K-1. These results were obtained with constant electrical conductivity. The combined influence of these two effects in case of the ideal composite structure should result in an increase of the thermoelectric efficiency parameter by three orders of magnitude.

Structure and properties of slow-resorbing nanofibers obtained by (co-axial electrospinning as tissue scaffolds in regenerative medicine

Directory of Open Access Journals (Sweden)

Andrzej Hudecki

2017-12-01

Full Text Available With the rapid advancement of regenerative medicine technologies, there is an urgent need for the development of new, cell-friendly techniques for obtaining nanofibers—the raw material for an artificial extracellular matrix production. We investigated the structure and properties of PCL10 nanofibers, PCL5/PCL10 core-shell type nanofibers, as well as PCL5/PCLAg nanofibres prepared by electrospinning. For the production of the fiber variants, a 5–10% solution of polycaprolactone (PCL (Mw = 70,000–90,000, dissolved in a mixture of formic acid and acetic acid at a ratio of 70:30 m/m was used. In order to obtain fibers containing PCLAg 1% of silver nanoparticles was added. The electrospin was conducted using the above-described solutions at the electrostatic field. The subsequent bio-analysis shows that synthesis of core-shell nanofibers PCL5/PCL10, and the silver-doped variant nanofiber core shell PCL5/PCLAg, by using organic acids as solvents, is a robust technique. Furthermore, the incorporation of silver nanoparticles into PCL5/PCLAg makes such nanofibers toxic to model microbes without compromising its biocompatibility. Nanofibers obtained such way may then be used in regenerative medicine, for the preparation of extracellular scaffolds: (i for controlled bone regeneration due to the long decay time of the PCL, (ii as bioscaffolds for generation of other types of artificial tissues, (iii and as carriers of nanocapsules for local drug delivery. Furthermore, the used solvents are significantly less toxic than the solvents for polycaprolactone currently commonly used in electrospin, like for example chloroform (CHCl3, methanol (CH3OH, dimethylformamide (C3H7NO or tetrahydrofuran (C4H8O, hence the presented here electrospin technique may allow for the production of multilayer nanofibres more suitable for the use in medical field.

Ti-Zr sponge material structure, obtained in the course of magnesium-thermal reduction

Energy Technology Data Exchange (ETDEWEB)

Sandler, R A; Aleksandrovskii, S V; Likhterman, V A; Golubev, A A; Kuz' menko, A S

1975-09-01

The paper describes the structure of Ti-Zr sponge for which a magnesium-thermic reduction has been employed. The influence of zirconium upon the sponge porous structure has been studied. The general trend lies in the sponge porosity increase as the content of zirconium grows. However this role is manifested in smaller or larger degrees depending upon the effect of other factors.

Structure and absolute configuration of Jurassic polyketide-derived spiroborate pigments obtained from microgram quantities.

OpenAIRE

Wolkenstein, K.; Sun , H.; Falk, H.; Griesinger, C.

2015-01-01

Complete structural elucidation of natural products is often challenging due to structural complexity and limited availability. This is true for present-day secondary metabolites, but even more for exceptionally preserved secondary metabolites of ancient organisms that potentially provide insights into the evolutionary history of natural products. Here, we report the full structure and absolute configuration of the borolithochromes, enigmatic boron-containing pigments from a Jurassic putative...

Efficient red organic electroluminescent devices based on trivalent europium complex obtained by designing the device structure with stepwise energy levels

Energy Technology Data Exchange (ETDEWEB)

Zhou, Liang; Jiang, Yunlong; Cui, Rongzhen; Li, Yanan; Zhao, Xuesen; Deng, Ruiping; Zhang, Hongjie, E-mail: hongjie@ciac.ac.cn

2016-02-15

In this study, we aim to further enhance the electroluminescence (EL) performances of trivalent europium complex Eu(TTA){sub 3}phen (TTA=thenoyltrifluoroacetone and phen=1,10-phenanthroline) by designing the device structure with stepwise energy levels. The widely used bipolar material 2,6-bis(3-(9H-carbazol-9-yl)phenyl)pyridine (26DCzPPy) was chosen as host material, while the doping concentration of Eu(TTA){sub 3}phen was optimized to be 4%. To facilitate the injection and transport of holes, MoO{sub 3} anode modification layer and 4,4′,4′′-Tris(carbazole-9-yl)triphenylamine (TcTa) hole transport layer were inserted in sequence. Efficient pure red emission with suppressed efficiency roll-off was obtained attributed to the reduction of accumulation holes, the broadening of recombination zone, and the improved balance of holes and electrons on Eu(TTA){sub 3}phen molecules. Finally, the device with 3 nm MoO{sub 3} and 5 nm TcTa obtained the highest brightness of 3278 cd/m{sup 2}, current efficiency of 12.45 cd/A, power efficiency of 11.50 lm/W, and external quantum efficiency of 6.60%. Such a device design strategy helps to improve the EL performances of emitters with low-lying energy levels and provides a chance to simplify device fabrication processes. - Highlights: • Electroluminescent performances of europium complex were further improved. • Device structure with stepwise energy levels was designed. • Better carriers' balance was realized by improving the injection and transport of holes. • The selection of bipolar host caused the broadening of recombination zone.

Development of the algorithm for obtaining 3-dimensional information using the structured light

Energy Technology Data Exchange (ETDEWEB)

Shin, Dong Uk; Lee, Jae Hyub; Kim, Chung Soo [Korea University of Technology and Education, Cheonan (Korea)

1998-03-01

The utilization of robot in atomic power plants or nuclear-related facilities has grown rapidly. In order to perform preassigned jobs using robot in nuclear-related facilities, advanced technology extracting 3D information of objects is essential. We have studied an algorithm to extract 3D information of objects using laser slit light and camera, and developed the following hardware system and algorithms. (1) We have designed and fabricated the hardware system which consists of laser light and two cameras. The hardware system can be easily installed on the robot. (2) In order to reduce the occlusion problem when measuring 3D information using laser slit light and camera, we have studied system with laser slit light and two cameras and developed algorithm to synthesize 3D information obtained from two cameras. (2) For easy use of obtained 3D information, we expressed it as digital distance image format and developed algorithm to interpolate 3D information of points which is not obtained. (4) In order to simplify calibration of the camera's parameter, we have also designed an fabricated LED plate, and developed an algorithm detecting the center position of LED automatically. We can certify the efficiency of developed algorithm and hardware system through experimental results. 16 refs., 26 figs., 1 tabs. (Author)

Structural, morphological, and thermal characterization of kraft lignin and its charcoals obtained at different heating rates

Science.gov (United States)

Rodrigues Brazil, Tayra; Nunes Costa, Rogeria; Massi, Marcos; Cerqueira Rezende, Mirabel

2018-04-01

Biomass is a renewable resource that is becoming more import due to environmental concerns and possible oil crisis. Thus, optimizing its use is a current challenge for many researchers. Lignin, which is a macromolecule with complex chemical structure, valuable physicochemical properties, and varied chemical composition, is available in large quantities in pulp and paper companies. The objective of this work is the physicochemical characterization of two Kraft lignin samples with different purities, and the study of its thermal conversion into charcoal. The lignin characterization was based on chemical, TGA, DSC, FT-IR, particle sizes, and FEG-SEM analyses. These analyses show that the lignins are mainly composed of guaiacyl and syringyl units, with residues of 30–36 wt.%, in inert atmosphere, depending on the lignin purity. From these results, the more purified lignin with higher carbon yield (%C) was selected for charcoal production. The heat treatment (HT) for carbonization of lignin, at different times (90, 180, and 420 min), resulted in different %C (41–44 wt.%). Longer HT resulted in higher %C and in charcoals with smaller pore sizes. Nanopores (∼50 nm) are observed for the charcoal obtained with the longest HT.

Predicting the biological effects of mobile phone radiation absorbed energy linked to the MRI-obtained structure.

Science.gov (United States)

Krstić, Dejan; Zigar, Darko; Petković, Dejan; Sokolović, Dušan; Dinđić, Boris; Cvetković, Nenad; Jovanović, Jovica; Dinđić, Nataša

2013-01-01

The nature of an electromagnetic field is not the same outside and inside a biological subject. Numerical bioelectromagnetic simulation methods for penetrating electromagnetic fields facilitate the calculation of field components in biological entities. Calculating energy absorbed from known sources, such as mobile phones when placed near the head, is a prerequisite for studying the biological influence of an electromagnetic field. Such research requires approximate anatomical models which are used to calculate the field components and absorbed energy. In order to explore the biological effects in organs and tissues, it is necessary to establish a relationship between an analogous anatomical model and the real structure. We propose a new approach in exploring biological effects through combining two different techniques: 1) numerical electromagnetic simulation, which is used to calculate the field components in a similar anatomical model and 2) Magnetic Resonance Imaging (MRI), which is used to accurately locate sites with increased absorption. By overlapping images obtained by both methods, we can precisely locate the spots with maximum absorption effects. This way, we can detect the site where the most pronounced biological effects are to be expected. This novel approach successfully overcomes the standard limitations of working with analogous anatomical models.

Recent advances of basic materials to obtain electrospun polymeric nanofibers for medical applications

Science.gov (United States)

Manea, L. R.; Hristian, L.; Leon, A. L.; Popa, A.

2016-08-01

The most important applications of electrospun polymeric nanofibers are by far those from biomedical field. From the biological point of view, almost all the human tissues and organs consist of nanofibroas structures. The examples include the bone, dentine, cartilage, tendons and skin. All these are characterized through different fibrous structures, hierarchically organized at nanometer scale. Electrospinning represents one of the nanotechnologies that permit to obtain such structures for cell cultures, besides other technologies, such as selfassembling and phase separation technologies. The basic materials used to produce electrospun nanofibers can be natural or synthetic, having polymeric, ceramic or composite nature. These materials are selected depending of the nature and structure of the tissue meant to be regenerated, namely: for the regeneration of smooth tissues regeneration one needs to process through electrospinning polymeric basic materials, while in order to obtain the supports for the regeneration of hard tissues one must mainly use ceramic materials or composite structures that permit imbedding the bioactive substances in distinctive zones of the matrix. This work presents recent studies concerning basic materials used to obtain electrospun polymeric nanofibers, and real possibilities to produce and implement these nanofibers in medical bioengineering applications.

A program for phase identification using diffractograms obtained from Tem structure images

Energy Technology Data Exchange (ETDEWEB)

Galicia, R.; Herrera, R.; Rius, J. L.; Zorrilla, C.; Gomez, A., E-mail: rherrera@fisica.unam.mx [UNAM, Instituto de Fisica, Apdo. Postal 20-364, 01000 Mexico D. F. (Mexico)

2013-05-01

In this work a computer program for the indexing of diffractograms is presented. The diffractograms are obtained by means of a discrete Fourier transform from high resolution electron microscope images. The program requires the use of X-ray diffraction data files together with a fast Fourier transform program, for this purpose we used the Digital Micrograph software. (Author)

A new numerical method for inverse Laplace transforms used to obtain gluon distributions from the proton structure function

Energy Technology Data Exchange (ETDEWEB)

Block, Martin M. [Northwestern University, Department of Physics and Astronomy, Evanston, IL (United States); Durand, Loyal [University of Wisconsin, Department of Physics, Madison, WI (United States)

2011-11-15

We recently derived a very accurate and fast new algorithm for numerically inverting the Laplace transforms needed to obtain gluon distributions from the proton structure function F{sub 2}{sup {gamma}}{sup p}(x,Q{sup 2}). We numerically inverted the function g(s), s being the variable in Laplace space, to G(v), where v is the variable in ordinary space. We have since discovered that the algorithm does not work if g(s){yields}0 less rapidly than 1/s as s{yields}{infinity}, e.g., as 1/s{sup {beta}} for 0 <{beta}<1. In this note, we derive a new numerical algorithm for such cases, which holds for all positive and non-integer negative values of {beta}. The new algorithm is exact if the original function G(v) is given by the product of a power v{sup {beta}}{sup -1} and a polynomial in v. We test the algorithm numerically for very small positive {beta}, {beta}=10{sup -6} obtaining numerical results that imitate the Dirac delta function {delta}(v). We also devolve the published MSTW2008LO gluon distribution at virtuality Q{sup 2}=5 GeV{sup 2} down to the lower virtuality Q{sup 2}=1.69 GeV{sup 2}. For devolution, {beta} is negative, giving rise to inverse Laplace transforms that are distributions and not proper functions. This requires us to introduce the concept of Hadamard Finite Part integrals, which we discuss in detail. (orig.)

Influence of film thickness on structural and optical properties of ZnS thin films obtained by SILAR method and analysis of Zn/ZnS/n-GaAs/In sandwich structure

Energy Technology Data Exchange (ETDEWEB)

Oezakin, Oguzhan; Guezeldir, Betuel; Saglam, Mustafa [Department of Physics, Science Faculty, Atatuerk University, Erzurum (Turkey); Yildirim, M. Ali [Department of Physics, Science and Art Faculty, Erzincan University, Erzincan (Turkey); Ates, Aytunc [Department of Material Engineering, Faculty of Engineering and Natural Sciences, Yildirim Beyazit University, Ankara (Turkey)

2012-04-15

ZnS thin films were deposited on glass substrates using SILAR method at room temperature and ambient pressure. The relationship between refractive index and energy bandgap was investigated. The film thickness effect on the structural, morphological and optical properties of ZnS thin films was investigated. The crystalline and surface properties of the films improved with increasing film thickness. The energy bandgap values changed from 3.87 to 3.58 eV with increasing film thickness. The refractive index (n), high frequency dielectric constant ({epsilon}{sub {infinity}}) values were calculated by using the energy bandgap values as a function of the film thickness. Also, ZnS thin film was deposited directly on n-GaAs substrate for obtaining the Zn/ZnS/n-GaAs/In sandwich structure at room temperature. The sandwich structure demonstrated clearly rectifying behaviour by the current-voltage (I-V) curves at room temperature. From I-V characteristics n and {phi}{sub b} values were calculated as 1.894 and 0.632 eV at room temperature, respectively. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Acoustic barriers obtained from industrial wastes.

Science.gov (United States)

Garcia-Valles, M; Avila, G; Martinez, S; Terradas, R; Nogués, J M

2008-07-01

Acoustic pollution is an environmental problem that is becoming increasingly more important in our society. Likewise, the accumulation of generated waste and the need for waste management are also becoming more and more pressing. In this study we describe a new material--called PROUSO--obtained from industrial wastes. PROUSO has a variety of commercial and engineering, as well as building, applications. The main raw materials used for this environmentally friendly material come from slag from the aluminium recycling process, dust from the marble industry, foundry sands, and recycled expanded polystyrene from recycled packaging. Some natural materials, such as plastic clays, are also used. To obtain PROUSO we used a conventional ceramic process, forming new mineral phases and incorporating polluted elements into the structure. Its physical properties make PROUSO an excellent acoustic and thermal insulation material. It absorbs 95% of the sound in the frequency band of the 500 Hz. Its compressive strength makes it ideal for use in ceramic wall building.

Optical and diffractive properties of polymer: nanoparticles periodic structures obtained by holographic method

Science.gov (United States)

Smirnova, T. N.; Sakhno, O. V.; Goldberg, L.; Stumpe, J.

2007-06-01

The ordering of nanoparticles in polymer matrix using holographic photopolymerization is investigated. The general approach to the selection of the photopolymerizable compounds is proposed. The nonlinear and luminescent properties of obtained gratings are studied.

Perovskite type nanopowders and thin films obtained by chemical methods

Directory of Open Access Journals (Sweden)

Viktor Fruth

2010-09-01

Full Text Available The review presents the contribution of the authors, to the preparation of two types of perovskites, namely BiFeO3 and LaCoO3, by innovative methods. The studied perovskites were obtained as powders, films and sintered bodies. Their complex structural and morphological characterization is also presented. The obtained results have underlined the important influence of the method of preparation on the properties of the synthesized perovskites.

Spectral inversion of frequency-domain IP data obtained in Haenam, South Korea

Science.gov (United States)

Kim, B.; Nam, M. J.; Son, J. S.

2017-12-01

Spectral induced polarization (SIP) method using a range of source frequencies have been performed for not only exploring minerals resources, but also engineering or environmental application. SIP interpretation first makes inversion of individual frequency data to obtain complex resistivity structures, which will further analyzed employing Cole-Cole model to explain the frequency-dependent characteristics. However, due to the difficulty in fitting Cole-Cole model, there is a movement to interpret complex resistivity structure inverted only from a single frequency data: that is so-called "complex resistivity survey". Further, simultaneous inversion of multi-frequency SIP data, rather than making a single frequency SIP data, has been studied to improve ambiguity and artefacts of independent single frequency inversion in obtaining a complex resistivity structure, even though the dispersion characteristics of complex resistivity with respect to source frequency. Employing the simultaneous inversion method, this study makes inversion of field SIP data obtained over epithermal mineralized area, Haenam, in the southernmost tip of South Korea. The area has a polarizable structure because of extensive hydrothermal alteration, gold-silver deposits. After the inversion, we compare between inversion results considering multi-frequency data and single frequency data set to evaluate the performance of simultaneous inversion of multi-frequency SIP data.

Fast-NPS-A Markov Chain Monte Carlo-based analysis tool to obtain structural information from single-molecule FRET measurements

Science.gov (United States)

Eilert, Tobias; Beckers, Maximilian; Drechsler, Florian; Michaelis, Jens

2017-10-01

The analysis tool and software package Fast-NPS can be used to analyse smFRET data to obtain quantitative structural information about macromolecules in their natural environment. In the algorithm a Bayesian model gives rise to a multivariate probability distribution describing the uncertainty of the structure determination. Since Fast-NPS aims to be an easy-to-use general-purpose analysis tool for a large variety of smFRET networks, we established an MCMC based sampling engine that approximates the target distribution and requires no parameter specification by the user at all. For an efficient local exploration we automatically adapt the multivariate proposal kernel according to the shape of the target distribution. In order to handle multimodality, the sampler is equipped with a parallel tempering scheme that is fully adaptive with respect to temperature spacing and number of chains. Since the molecular surrounding of a dye molecule affects its spatial mobility and thus the smFRET efficiency, we introduce dye models which can be selected for every dye molecule individually. These models allow the user to represent the smFRET network in great detail leading to an increased localisation precision. Finally, a tool to validate the chosen model combination is provided. Programme Files doi:http://dx.doi.org/10.17632/7ztzj63r68.1 Licencing provisions: Apache-2.0 Programming language: GUI in MATLAB (The MathWorks) and the core sampling engine in C++ Nature of problem: Sampling of highly diverse multivariate probability distributions in order to solve for macromolecular structures from smFRET data. Solution method: MCMC algorithm with fully adaptive proposal kernel and parallel tempering scheme.

Early Delivery of Misfolded PrP from ER to Lysosomes by Autophagy

Science.gov (United States)

Cortes, Constanza J.; Qin, Kefeng; Norstrom, Eric M.; Green, William N.; Bindokas, Vytautas P.; Mastrianni, James A.

2013-01-01

Prion diseases are linked to the accumulation of a misfolded isoform (PrPSc) of prion protein (PrP). Evidence suggests that lysosomes are degradation endpoints and sites of the accumulation of PrPSc. We questioned whether lysosomes participate in the early quality control of newly generated misfolded PrP. We found PrP carrying the disease-associated T182A mutation (Mut-PrP) was delivered to lysosomes in a Golgi-independent manner. Time-lapse live cell imaging revealed early formation and uptake of GFP-tagged Mut-PrP aggregates into LysoTracker labeled vesicles. Compared with Wt-PrP, Mut-PrP expression was associated with an elevation in several markers of the autophagy-lysosomal pathway, and it extensively colocalized with the autophagosome-specific marker, LC3B. In autophagy deficient (ATG5−/−) mouse embryonic fibroblasts, or in normal cells treated with the autophagy-inhibitor 3-MA, Mut-PrP colocalization with lysosomes was reduced to a similar extent. Additionally, 3-MA selectively impaired the degradation of insoluble Mut-PrP, resulting in an increase in protease-resistant PrP, whereas the induction of autophagy by rapamycin reduced it. These findings suggest that autophagy might function as a quality control mechanism to limit the accumulation of misfolded PrP that normally leads to the generation of PrPSc. PMID:24454378

Comparative Study of Prions in Iatrogenic and Sporadic Creutzfeldt-Jakob Disease

Science.gov (United States)

Xiao, Xiangzhu; Yuan, Jue; Qing, Liuting; Cali, Ignazio; Mikol, Jacqueline; Delisle, Marie-Bernadette; Uro-Coste, Emmanuelle; Zeng, Liang; Abouelsaad, Mai; Gazgalis, Dimitris; Martinez, Manuel Camacho; Wang, Gong-Xian; Brown, Paul; Ironside, James W.; Gambetti, Pierluigi; Kong, Qingzhong; Zou, Wen-Quan

2014-01-01

Differentiating iatrogenic Creutzfeldt-Jakob disease (iCJD) from sporadic CJD (sCJD) would be useful for the identification and prevention of human-to-human prion transmission. Currently, the diagnosis of iCJD depends on identification of a recognized source of contamination to which patients have been exposed, in addition to fulfilling basic requirements for the establishment of diagnosis of CJD. Attempts to identify differences in clinical manifestations, neuropathological changes and pathological prion protein (PrPSc) between iCJD and sCJD have been unsuccessful. In the present study, using a variety of more sophisticated methods including sucrose step gradient sedimentation, conformational stability immunoassay, protein misfolding cyclic amplification (PMCA), fragment-mapping, and transmission study, we show no significant differences in gel profiles, oligomeric state, conformational stability and infectivity of PrPSc between iCJD and sCJD. However, using PMCA, we find that convertibility and amplification efficiency of PrPSc is greater in iCJD than in sCJD in a polymorphism-dependent manner. Moreover, two protease-resistant PrP C-terminal fragments (termed PrP-CTF12/13) were detected in all 9 cases of sCJD but not in 6 of 8 cases of iCJD tested in this study. The use of fragment mapping- and PMCA-based assays thus provides a means to distinguish most cases of iCJD from sCJD. PMID:25419482

Characterization of some etalon matrices obtained by cement conditioning of the radioactive sludge

International Nuclear Information System (INIS)

Nicu, M.; Mihai, F.

1998-01-01

The aim of this work was to establish new ways of investigation of some compounds which are important for studying physico-mechanical mechanisms, nature and structure of the intermediate and final products oc curing in reactions of the technological conditioning processes of the radioactive wastes by cementation after their treatment by precipitation or sorption process. Cement conditioning is, presently, the most used technology for the low and intermediate level waste treatment. Besides many advantages it also presents some disadvantages which limit the utilization area depending, firstly, on the chemical composition of the conditioned radioactive waste. In this work, the influence of different iron precipitates on cement structure is studied and assessed by changes in phase composition and mechanical resistance. Using mechanical resistance data, X-rays diffraction spectra and Moessbauer spectroscopy for iron precipitates and cement-iron precipitate samples, we obtained an image concerning chemical reactions and modifications which appear when iron precipitate is included in cement, between major components of cement and the added one. Moessbauer spectroscopy and X-rays diffraction were proved to be very useful to establish composition and structure of iron compounds used in treatment technology by chemical precipitation. Precipitation mechanism may be elucidated only by a thoroughgoing study of intermediate compounds obtained in successive precipitation phases. Depending on precipitation procedure, initial iron cations and order of adding of reactants, it was observed that the structure of finally obtained precipitates is different. Obtained results at compression tests on cement-iron precipitate samples are similarly with those obtained for reference cement matrix. These results demonstrate that iron precipitate in the sample with precipitate/cement ratio of 1/2 does not influence the mechanical resistance of the obtained matrix The presented results are in

The sort of carburization and the quality of obtained cast iron

Directory of Open Access Journals (Sweden)

K. Janerka

2008-12-01

Full Text Available In the production of cast iron, the pig iron’s amount in charge material is more and more often limited, and replaced by steel scrap. That extorts the necessity of know-how the carburization and one is looking for carburizers, which ensure obtaining big carbon increment as quickly as possible with the high repeatability and the ones which ensure getting the adequate quality of cast iron. The object of presented research was definition of the influence of charge materials’ sort on the structure, course of solidification, and the effectiveness of process. The cast iron melts, which are presented below, are made only on the basis of steel scrap with portion of graphitoidal, coke and anthracite carburizers, which were added to the charge in solid. In the article one compared the carburizers in respect of their structure, chemical constitution and the effectiveness obtained during the carburization of liquid metal. The melting of cast iron, based on the special pig iron, was carried out as well. The course of melts, chemical constitution of obtained cast iron and its structure were presented. The comparison between quality distribution and the volume fraction of graphite in classes of size for the individual melts were achieved and the TDA curves were inserted.

On Obtaining Design Allowables for Adhesives Used in the Bonded-Composite Repair of Aircraft

National Research Council Canada - National Science Library

Chalkley, Peter

1998-01-01

A technique is documented, along with its experimental validation, for obtaining engineering-standard design allowables for structural adhesives used in the bonded/composite repair of aircraft structure...

Comparison of different methodologies for obtaining nickel nanoferrites

Energy Technology Data Exchange (ETDEWEB)

Galindo, R.; Menendez, N. [Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Crespo, P.; Velasco, V. [Instituto de Magnetismo Aplicado, UCM, ADIF CSIC, E-28230 Madrid (Spain); Bomati-Miguel, O.; Díaz-Fernández, D. [Departamento de Física Aplicada and Instituto Nicolás Cabrera, Facultad de Ciencias Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Departamento de Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)

2014-06-01

Nickel nanoferrites were obtained by means of four different synthetic wet-routes: co-precipitation (CP), sonochemistry (SC), sonoelectrochemistry (SE) and electrochemistry (E). The influence of the synthesis method on the structural and magnetic properties of nickel ferrite nanoparticles is studied. Although similar experimental conditions such as temperature, pH and time of synthesis were used, a strong dependence of composition and microstructure on the synthesis procedure is found, as electron microscopy, X-ray diffraction and Mössbauer spectroscopy studies reveal. Whereas by means of the CP and SC methods particles of a small size around 5–10 nm, respectively, and composed by different phases are obtained, the electrochemical routes (E and SE) allow obtaining monodisperse nanoparticles, with sizes ranging from 30 to 40 nm, and very close to stoichiometry. Magnetic characterization evidences a superparamagnetic behavior for samples obtained by CP and SC methods, whereas the electrochemical route leads to ferromagnetic ferrite nanoparticles. - Highlights: • Electrochemical synthesis produces pure NiFe{sub 2}O{sub 4} nanonoparticles with 40 nm particle size. • Coprecipitation and sonochemistry techniques generate NiFe{sub 2}O{sub 4} nanoparticles with impurities. • Nanoparticles obtained by coprecipitation and sonochemistry are superparamagnetic. • Electrochemical and sonoelectrochemical methods produce ferromagnetic nanoparticles.

Transmissibility of H-Type Bovine Spongiform Encephalopathy to Hamster PrP Transgenic Mice.

Directory of Open Access Journals (Sweden)

Hiroyuki Okada

Full Text Available Two distinct forms of atypical bovine spongiform encephalopathies (H-BSE and L-BSE can be distinguished from classical (C- BSE found in cattle based on biochemical signatures of disease-associated prion protein (PrPSc. H-BSE is transmissible to wild-type mice-with infected mice showing a long survival period that is close to their normal lifespan-but not to hamsters. Therefore, rodent-adapted H-BSE with a short survival period would be useful for analyzing H-BSE characteristics. In this study, we investigated the transmissibility of H-BSE to hamster prion protein transgenic (TgHaNSE mice with long survival periods. Although none of the TgHaNSE mice manifested the disease during their lifespan, PrPSc accumulation was observed in some areas of the brain after the first passage. With subsequent passages, TgHaNSE mice developed the disease with a mean survival period of 220 days. The molecular characteristics of proteinase K-resistant PrPSc (PrPres in the brain were identical to those observed in first-passage mice. The distribution of immunolabeled PrPSc in the brains of TgHaNSE mice differed between those infected with H-BSE as compared to C-BSE or L-BSE, and the molecular properties of PrPres in TgHaNSE mice infected with H-BSE differed from those of the original isolate. The strain-specific electromobility, glycoform profiles, and proteolytic cleavage sites of H-BSE in TgHaNSE mice were indistinguishable from those of C-BSE, in which the diglycosylated form was predominant. These findings indicate that strain-specific pathogenic characteristics and molecular features of PrPres in the brain are altered during cross-species transmission. Typical H-BSE features were restored after back passage from TgHaNSE to bovinized transgenic mice, indicating that the H-BSE strain was propagated in TgHaNSE mice. This could result from the overexpression of the hamster prion protein.

Scrapie infectivity is quickly cleared in tissues of orally-infected farmed fish

Directory of Open Access Journals (Sweden)

Faoro Franco

2006-06-01

Full Text Available Abstract Background Scrapie and bovine spongiform encephalopathy (BSE belongs to the group of animal transmissible spongiform encephalopathy (TSE. BSE epidemic in the UK and elsewhere in Europe has been linked to the use of bovine meat and bone meals (MBM in the feeding of cattle. There is concern that pigs, poultry and fish bred for human consumption and fed with infected MBM would eventually develop BSE or carry residual infectivity without disease. Although there has been no evidence of infection in these species, experimental data on the susceptibility to the BSE agent of farm animals other than sheep and cow are limited only to pigs and domestic chicken. In the framework of a EU-granted project we have challenged two species of fish largely used in human food consumption, rainbow trout (Oncorhynchus mykiss and turbot (Scophthalmus maximus, with a mouse-adapted TSE strain (scrapie 139A, to assess the risk related to oral consumption of TSE contaminated food. In trout, we also checked the "in vitro" ability of the pathological isoform of the mouse prion protein (PrPSc to cross the intestinal epithelium when added to the mucosal side of everted intestine. Results Fish challenged with a large amount of scrapie mouse brain homogenate by either oral or parenteral routes, showed the ability to clear the majority of infectivity load. None of the fish tissues taken at different time points after oral or parenteral inoculation was able to provoke scrapie disease after intracerebral inoculation in recipient mice. However, a few recipient mice were positive for PrPSc and spongiform lesions in the brain. We also showed a specific binding of PrPSc to the mucosal side of fish intestine in the absence of an active uptake of the prion protein through the intestinal wall. Conclusion These results indicate that scrapie 139A, and possibly BSE, is quickly removed from fish tissues despite evidence of a prion like protein in fish and of a specific binding of PrPSc

Distinct pathological phenotypes of Creutzfeldt-Jakob disease in recipients of prion-contaminated growth hormone.

Science.gov (United States)

Cali, Ignazio; Miller, Cathleen J; Parisi, Joseph E; Geschwind, Michael D; Gambetti, Pierluigi; Schonberger, Lawrence B

2015-06-25

The present study compares the clinical, pathological and molecular features of a United States (US) case of growth hormone (GH)-associated Creutzfeldt-Jakob disease (GH-CJD) (index case) to those of two earlier referred US cases of GH-CJD and one case of dura mater (d)-associated CJD (dCJD). All iatrogenic CJD (iCJD) subjects were methionine (M) homozygous at codon 129 (129MM) of the prion protein (PrP) gene and had scrapie prion protein (PrP(Sc)) type 1 (iCJDMM1). The index subject presented with ataxia, weight loss and changes in the sleep pattern about 38 years after the midpoint of GH treatment. Autopsy examination revealed a neuropathological phenotype reminiscent of both sCJDMV2-K (a sporadic CJD subtype in subjects methionine/valine heterozygous at codon 129 with PrP(Sc) type 2 and the presence of kuru plaques) and variant CJD (vCJD). The two earlier cases of GH-CJDMM1 and the one of dCJDMM1 were associated with neuropathological phenotypes that differed from that of the index case mainly because they lacked PrP plaques. The phenotype of the earlier GH-CJDMM1 cases shared several, but not all, characteristics with sCJDMM1, whereas dCJDMM1 was phenotypically indistinguishable from sCJDMM1. Two distinct groups of dCJDMM1 have also been described in Japan based on clinical features, the presence or absence of PrP plaques and distinct PK-resistant PrP(Sc) (resPrP(Sc)) electrophoretic mobilities. The resPrP(Sc) electrophoretic mobility was, however, identical in our GH-CJDMM1 and dCJDMM1 cases, and matched that of sCJDMM1. Our study shows that receipt of prion-contaminated GH can lead to a prion disease with molecular features (129MM and PrP(Sc) type 2) and phenotypic characteristics that differ from those of sporadic prion disease (sCJDMM1), a difference that may reflect adaptation of "heterologous" prion strains to the 129MM background.

Obtaining carbon nanotubes/ZnO for use in the photocatalytic organic pollutants

International Nuclear Information System (INIS)

Dalt, S. da; Pulcinelli, N.O.; Bergmann, C.P.

2016-01-01

This study aims to obtain nanocomposites of carbon nanotubes (CNTs) with nanostructured zinc oxide (ZnO), and characterize the samples as its structure and photocatalytic activity, for their application in the degradation of organic pollutants, in the case organic dye methyl orange. The nanocomposites were obtained from commercial NTC (Baytubes®), commercial ZnO, produced by Merck and ZnO obtained from the synthesis by combustion. The NTC-ZnO nanocomposites were prepared in solution from the physical mixture of materials, and subsequently analyzed structurally and investigated for their photocatalytic activity, employing them as catalysts in degradation of the dye in aqueous solution under ultraviolet radiation. Samples were analyzed by X-ray diffraction and specific surface area (BET). The photocatalytic performance of nanocomposites can be correlated to the phase found and the surface area measured. (author)

Medium-range structural properties of vitreous germania obtained through first-principles analysis of vibrational spectra.

Science.gov (United States)

Giacomazzi, Luigi; Umari, P; Pasquarello, Alfredo

2005-08-12

We analyze the principal vibrational spectra of vitreous GeO(2) and derive therefrom structural properties referring to length scales beyond the basic tetrahedral unit. We generate a model structure that yields a neutron structure factor in accord with experiment. The inelastic-neutron, the infrared, and the Raman spectra, calculated within a density-functional approach, also agree with respective experimental spectra. The accord for the Raman spectrum supports a Ge-O-Ge angle distribution centered at 135 degrees. The Raman feature X(2) is found to result from vibrations in three-membered rings, and therefore constitutes a distinctive characteristic of the medium-range structure.

On Ti-Zr sponge material structure, obtained in the course of magnesium-thermal reduction

International Nuclear Information System (INIS)

Sandler, R.A.; Aleksandrovskij, S.V.; Likhterman, V.A.; Golubev, A.A.; Kuz'menko, A.S.

1975-01-01

The paper describes the structure of Ti-Zr sponge for which a magnesium-thermic reduction has been employed. The influence of zirconium upon the sponge porous structure has been studied. The general trend lies in the sponge porosity increase as the content of zirconium grows. However this role is manifested in a smaller or larger degrees depending upon the effect of other factors

Chromium-nanodiamond coatings obtained by magnetron sputtering and their tribological properties

Science.gov (United States)

Atamanov, M. V.; Khrushchov, M. M.; Marchenko, E. A.; Shevchenko, N. V.; Levin, I. S.; Petrzhik, M. I.; Miroshnichenko, V. I.; Relianu, M. D.

2017-07-01

Peculiarities of structure, chemical and phase composition, micromechanical and tribological properties of chromium-based coatings obtained by magnetron-sputtering of composite and/or compacted chromium-nanodiamond targets have been investigated.

Scope and limitations of high energy electron scattering in obtaining relevant structural information about atoms and molecules

International Nuclear Information System (INIS)

Ketkar, S.N.

1984-01-01

During the course of this work experiments were undertaken to measure the scattering cross-sections for high energy electrons scattering from various target systems. The experiments can be broadly classified into two categories, one dealing with rather small systems and the other dealing with large systems (at least in the view of physicists). Although the experimental aspects, in so much as the experimental measurement of the intensities of the scattered electron is concerned, is the same for both the cases the motivation for performing the experiment is totally different. In the first case, simple atomic and molecular target systems, namely He, H 2 and D 2 , are used. For such systems, good theoretical framework is available and critical comparisons of experimental cross sections are made with theoretical predictions. Attention is focussed mainly at small momentum transfer (up to 10A -1 ), and correlation and binding effects are studied. In the second case, somewhat larger molecular systems, namely naphthalene, anthraquinone, anthracene and dichromium tetraacetate are used. For such systems attention is focused at large momentum transfer (from 10 to 25 A -1 ) to obtain structural information about the molecules

Structure and evaluation of antibacterial and antitubercular properties of new basic and heterocyclic 3-formylrifamycin SV derivatives obtained via 'click chemistry' approach.

Science.gov (United States)

Pyta, Krystian; Klich, Katarzyna; Domagalska, Joanna; Przybylski, Piotr

2014-09-12

Thirty four novel derivatives of 3-formylrifamycin SV were synthesized via reductive alkylation and copper(I)-catalysed azide-alkyne cycloaddition. According to the obtained results, 'click chemistry' can be successfully applied for modification of structurally complex antibiotics such as rifamycins, with the formation of desired 1,2,3-triazole products. However, when azide-alkyne cycloaddition on 3-formylrifamycin SV derivatives demanded higher amount of catalyst, lower temperature and longer reaction time because of the high volatility of substrates, an unexpected intramolecular condensation with the formation of 3,4-dihydrobenzo[g]quinazoline heterocyclic system took place. Structures of new derivatives in solution were determined using one- and two-dimensional NMR methods and FT-IR spectroscopy. Computational DFT and PM6 methods were employed to correlate their conformation and acid-base properties to biological activity and establish SAR of the novel compounds. Microbiological, physico-chemical (logP, solubility) and structural studies of newly synthesised rifamycins indicated that for the presence of relatively high antibacterial (MIC ~0.01 nmol/mL) and antitubercular (MIC ~0.006 nmol/mL) activities, a rigid and basic substituent at C(3) arm, containing a protonated nitrogen atom "open" toward intermolecular interactions, is required. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Morphology and physical-chemical properties of celluloses obtained by different methods

Science.gov (United States)

Anpilova, A. Yu.; Mastalygina, E. E.; Mikhaylov, I. A.; Popov, A. A.; Kartasheva, Z. S.

2017-12-01

The morphology and structural characteristics of celluloses obtained by different methods were studied. The objects of the investigation are cellulose from pulp source, commercial celluloses produced by sodium and acid hydrolysis, laboratory produced cellulose from bleached birch kraft pulp, and cellulose obtained by thermooxidative catalytic treatment of maple leaves by peroxide. According to a complex analysis of cellulose characteristics, several types of celluloses were offered as modifying additives for polymers.

Obtaining of graded zones in glass by diffusion from the paste

International Nuclear Information System (INIS)

Valov, P.M.; Goldenfant, B.G.; Polyanskiy, M.N.

1986-01-01

The local changing of refraction index of glass matrix by treatment of alloy of salts from solid source-paste is studied in this article. Paste was produced of mixture of binder and salts of lithium, sodium, potassium, and copper. The paste was applied on matrix surface and obtained item was thermal processed. Influence of electrical and temperature ranges on optical and geometrical properties of obtained structures is studied as well.

Tungsten oxide thin films obtained by anodisation in low electrolyte concentration

Energy Technology Data Exchange (ETDEWEB)

Costa, Nadja B.D. da [Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, Campus Capão do Leão, s/n, Pelotas, RS (Brazil); Pazinato, Julia C.O. [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Sombrio, Guilherme; Pereira, Marcelo B.; Boudinov, Henri [Instituto de Física, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil); Gündel, André; Moreira, Eduardo C. [Universidade Federal do Pampa, Travessa 45, 1650 Bagé, RS (Brazil); Garcia, Irene T.S., E-mail: irene.garcia@ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500 Porto Alegre, RS (Brazil)

2015-03-02

Tungsten oxide nanostructured films were grown on tungsten substrates by anodisation under a fixed voltage and with sodium fluoride as electrolyte. The effect of the anion chloride and the influence of the modifying agent disodium hydrogen phosphate in the tungsten oxide films were also investigated. The structural characterisation of the films was performed by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The band gap was determined through diffuse reflectance spectroscopy. The thin films were photoluminescent and emitted in the range of 300 to 630 nm when irradiated at 266 nm. The synthesised films efficiently degraded of methyl orange dye in the presence of hydrogen peroxide and 250 nm radiation. The modifying agent was responsible for the improvement of the photocatalytic activity. Films with similar photocatalytic performance were obtained when the system sodium fluoride and disodium hydrogen phosphate were replaced by sodium chloride. The porous structure and low band gap values were responsible for the photocatalytic behaviour. - Highlights: • Tungsten oxide thin films were obtained by anodisation of tungsten in aqueous media. • The performance of the NaCl, NaF and NaF/Na{sub 2}HPO{sub 4} as electrolytes was investigated. • The relation between structure and optical behaviour has been discussed. • Films obtained with NaCl and NaF/Na{sub 2}HPO{sub 4} present similar photocatalytic activity.

Silver nanoplates with ground or metastable structures obtained from template-free two-phase aqueous/organic synthesis

Energy Technology Data Exchange (ETDEWEB)

Zhelev, Doncho V., E-mail: dontcho.jelev@nih.gov; Zheleva, Tsvetanka S. [Army Research Laboratory, 2800 Adelphi, Maryland 20783 (United States)

2014-01-28

Silver has unique electrical, catalytic, and plasmonic characteristics and has been widely sought for fabrication of nanostructures. The properties of silver nanostructures are intimately coupled to the structure of silver crystals. Two crystal structures are known for silver: the stable (ground) state cubic face centered 3C-Ag structure and the metastable hexagonal 4H-Ag structure. Recently, Chackraborty et al. [J. Phys.: Condens. Matter 23, 325401 (2011)] discovered a low density, highly reactive metastable hexagonal 2H-Ag structure accessible during electrodeposition of silver nanowires in porous anodic alumina templates. This 2H-Ag structure has enhanced electrical and catalytic characteristics. In the present work we report template-free synthesis of silver nanoplates with the metastable 2H-Ag crystal structure, which appears together with the ground 3C-Ag and the metastable 4H-Ag structures in a two-phase solution synthesis with citric acid as the capping agent. The capacity of citric acid to stabilize both the stable and the metastable structures is explained by its preferential binding to the close packed facets of Ag crystals, which are the (111) planes for 3C-Ag and the (0001) planes for 4H-Ag and 2H-Ag. Nanoplate morphology and structure are characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The synthesized nanoplates have thickness from 15 to 17 nm and edge length from 1 to 10 μm. Transmission electron microscopy selected area electron diffraction is used to uniquely identify and distinguish between nanoplates with 2H-Ag or 4H-Ag or 3C-Ag structures.

Study of electrochemical properties of the Prussian blue obtained via pentacyanidoferrate complex

Energy Technology Data Exchange (ETDEWEB)

Monteiro, Marcio Cristiano; Toledo, Kalil Cristhian Figueiredo; Pires, Bruno Morandi; Bonacin, Juliano Alves, E-mail: monteiromarcioc@gmail.com [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Instituto de Quimica; Wick, Rene [University of Zurich (Switzerland)

2016-07-01

Full text: Prussian blue (PB) is one the most important compounds used in electrochemical sensing of molecular targets as H{sub 2}O{sub 2}. Many diseases or biochemical abnormalities can be diagnosed by analysis of H{sub 2}O{sub 2}. The properties found in PB comes from the electronic structure of this material which is formed by Fe{sup 2+} bonded to iron Fe{sup 3+} by cyanide bridged arranged in a 3D structure. Furthermore, the intervalence observed allows to achieve different levels of oxidation in the same process[1]. The challenge in this area is how to control and modulate specific features of PB. Because of this, we are interested in evaluating how the ligand Nmethylpyrazinium affects the structure and reactivity of the N-methylpyraziniumpentacyanidoferrate(II)(PCF) and its PB corresponding. According to XRD, the PB obtained from PCF produces an amorphous structure instead of the highly ordered structure of PB obtained by classical methods. The stoichiometry of formation of the PB(classic) obtained by the Job's method is 1: 1 (Fe(III): [Fe(CN){sub 6}]{sup 4-}), on the other hand, in PB-PCF the stoichiometry is 1: 2 (Fe(III):PCF). The reported features cause differences in the oxidation potential of the films, PB(classic) Eox=0.167V and PB-PCF Eox=0.219V. In terms of sensing of H{sub 2}O{sub 2}, the PB(classic) presented LOD= 1.2 10{sup -4} M and PB-mpz LOD= 5.8 10{sup -5}M. We have concluded that different sources of iron complexes cause alterations in the organization and electronic structure of the PB. Reference: [1] B. M. Pires, S. A. V. Jannuzzi, A. L. B. Formiga, J. A. Bonacin, Eur J Inorg Chem, 5812, (2014). (author)

Nanostructured synthetic carbons obtained by pyrolysis of spherical acrylonitrile/divinylbenzene copolymers.

Directory of Open Access Journals (Sweden)

Danish J Malik

Full Text Available Novel carbon materials have been prepared by the carbonization of acrylonitrile (AN/divinylbenzene (DVB suspension porous copolymers having nominal crosslinking degrees in the range of 30-70% and obtained in the presence of various amounts of porogens. The carbons were obtained by pre-oxidation of AN/DVB copolymers at 250-350°C in air followed by pyrolysis at 850°C in an N(2 atmosphere. Both processes were carried out in one furnace and the resulting material needed no further activation. Resulting materials were characterized by XPS and low temperature nitrogen adsorption/desorption. It was found that maximum pyrolysis yield was ca. 50% depending on the oxidation conditions but almost independent of the crosslinking degree of the polymers. Porous structure of the carbons was characterized for the presence of micropores and macropores, when obtained from highly crosslinked polymers or polymers oxidized at 350°C and meso- and macropores in all other cases. The latter pores are prevailing in the structure of carbons obtained from less porous AN/DVB resins. Specific surface area (BET of polymer derived carbons can vary between 440 m(2/g and 250 m(2/g depending on the amount of porogen used in the synthesis of the AN/DVB polymeric precursors.

Electromagnetic and structural interaction analysis of curved shell structures

International Nuclear Information System (INIS)

Horie, T.; Niho, T.

1993-01-01

This paper describes a finite element formulation of the eddy current and structure coupled problem for curved shell structures. Coupling terms produced by curved geometry as well as flat plate geometry were obtained. Both matrix equations for eddy current and structure were solved simultaneously using coupling sub-matrices. TEAM Workshop bench mark problem 16 was solved to verify the formulation and the computer code. Agreement with experimental results was very good for such plate problem. A coupled problem for cylindrical shell structure was also analyzed. Influence of each coupling term was examined. The next topic is the eigenvalues of the coupled equations. Although the coupled matrix equations are not symmetric, symmetry was obtained by introducing a symmetrizing variable. The eigenvalues of the coupled matrix equations are different from those obtained from the uncoupled equations because of the influence of the coupling sub-matrix components. Some parameters obtained by the eigenvalue analysis have characteristics of parameters which indicate the intensity of electromagnetic structural coupling effect. (author)

Dielectric properties of supramolecular ionic structures obtained from multifunctional carboxylic acids and amines

DEFF Research Database (Denmark)

Gonzalez, Lidia; Yu, Liyun; Hvilsted, Søren

2014-01-01

The dielectric properties of several supramolecular ionic polymers and networks, linked by the ammonium salts of hexamethylene diamine (HMDA), tris(2-aminoethyl)amine (TAEA), poly(propylene imine) (PPI) dendrimers and two short bis carboxymethyl ether-terminated poly(ethylene glycol)s (Di......COOH-PEG), are reported in this paper. All supramolecular ionic polymers and networks exhibit very high relative dielectric permittivities ( 3 0 )( 10 2 – 10 6 ) at low frequencies, and signi fi cantly lower values (from 1 up to 26) at high frequencies. Additionally, the dielectric properties of supramolecular ionic......), are investigated. Here the relative dielectric permittivities of the supramolecular ionic structures formed with the multifunctional carboxylic acids were lower than those from the supramolecular ionic structures formed with the two carboxymethyl ether-terminated poly(ethylene glycol)s....

Propeller-Shaped ZnO Nano structures Obtained by Chemical Vapor Deposition: Photoluminescence and Photo catalytic Properties

International Nuclear Information System (INIS)

Wang, S.L.; Zhu, H.W.; Li, P.G.; Tang, W.H.

2012-01-01

Propeller-shaped and flower-shaped ZnO nano structures on Si substrates were prepared by a one-step chemical vapor deposition technique. The propeller-shaped ZnO nano structure consists of a set of axial nano rod (50 nm in tip, 80 nm in root and 1μm in length), surrounded by radial-oriented nano ribbons (20-30 nm in thickness and 1.5μm in length). The morphology of flower-shaped ZnO nano structure is similar to that of propeller-shaped ZnO, except the shape of leaves. These nano rods leaves (30?nm in diameter and 1-1.5μm in length) are aligned in a radial way and pointed toward a common center. The flower-shaped ZnO nano structures show sharper and stronger UV emission at 378 nm than the propeller-shaped ZnO, indicating a better crystal quality and fewer structural defects in flower-shaped ZnO. In comparison with flower-shaped ZnO nano structures, the propeller-shaped ZnO nano structures exhibited a higher photo catalytic property for the photo catalytic degradation of Rhodamine B under UV-light illumination.

Inactivation of Template-Directed Misfolding of Infectious Prion Protein by Ozone

Science.gov (United States)

Ding, Ning; Price, Luke M.; Braithwaite, Shannon L.; Balachandran, Aru; Belosevic, Miodrag

2012-01-01

Misfolded prions (PrPSc) are well known for their resistance to conventional decontamination processes. The potential risk of contamination of the water environment, as a result of disposal of specified risk materials (SRM), has raised public concerns. Ozone is commonly utilized in the water industry for inactivation of microbial contaminants and was tested in this study for its ability to inactivate prions (263K hamster scrapie = PrPSc). Treatment variables included initial ozone dose (7.6 to 25.7 mg/liter), contact time (5 s and 5 min), temperature (4°C and 20°C), and pH (pH 4.4, 6.0, and 8.0). Exposure of dilute suspensions of the infected 263K hamster brain homogenates (IBH) (0.01%) to ozone resulted in the in vitro destruction of the templating properties of PrPSc, as measured by the protein misfolding cyclic amplification (PMCA) assay. The highest levels of prion inactivation (≥4 log10) were observed with ozone doses of 13.0 mg/liter, at pH 4.4 and 20°C, resulting in a CT (the product of residual ozone concentration and contact time) value as low as 0.59 mg · liter−1 min. A comparison of ozone CT requirements among various pathogens suggests that prions are more susceptible to ozone degradation than some model bacteria and protozoa and that ozone treatment may be an effective solution for inactivating prions in water and wastewater. PMID:22138993

PrPST, a Soluble, Protease Resistant and Truncated PrP Form Features in the Pathogenesis of a Genetic Prion Disease

Science.gov (United States)

Frid, Kati; Binyamin, Orli; Gabizon, Ruth

2013-01-01

While the conversion of PrPC into PrPSc in the transmissible form of prion disease requires a preexisting PrPSc seed, in genetic prion disease accumulation of disease related PrP could be associated with biochemical and metabolic modifications resulting from the designated PrP mutation. To investigate this possibility, we looked into the time related changes of PrP proteins in the brains of TgMHu2ME199K/wt mice, a line modeling for heterozygous genetic prion disease linked to the E200K PrP mutation. We found that while oligomeric entities of mutant E199KPrP exist at all ages, aggregates of wt PrP in the same brains presented only in advanced disease, indicating a late onset conversion process. We also show that most PK resistant PrP in TgMHu2ME199K mice is soluble and truncated (PrPST), a pathogenic form never before associated with prion disease. We next looked into brain samples from E200K patients and found that both PK resistant PrPs, PrPST as in TgMHu2ME199K mice, and “classical” PrPSc as in infectious prion diseases, coincide in the patient's post mortem brains. We hypothesize that aberrant metabolism of mutant PrPs may result in the formation of previously unknown forms of the prion protein and that these may be central for the fatal outcome of the genetic prion condition. PMID:23922744

Infectious prion diseases in humans: cannibalism, iatrogenicity and zoonoses.

Science.gov (United States)

Haïk, Stéphane; Brandel, Jean-Philippe

2014-08-01

In contrast with other neurodegenerative disorders associated to protein misfolding, human prion diseases include infectious forms (also called transmitted forms) such as kuru, iatrogenic Creutzfeldt-Jakob disease and variant Creutzfeldt-Jakob disease. The transmissible agent is thought to be solely composed of the abnormal isoform (PrP(Sc)) of the host-encoded prion protein that accumulated in the central nervous system of affected individuals. Compared to its normal counterpart, PrP(Sc) is β-sheet enriched and aggregated and its propagation is based on an autocatalytic conversion process. Increasing evidence supports the view that conformational variations of PrP(Sc) encoded the biological properties of the various prion strains that have been isolated by transmission studies in experimental models. Infectious forms of human prion diseases played a pivotal role in the emergence of the prion concept and in the characterization of the very unconventional properties of prions. They provide a unique model to understand how prion strains are selected and propagate in humans. Here, we review and discuss how genetic factors interplay with strain properties and route of transmission to influence disease susceptibility, incubation period and phenotypic expression in the light of the kuru epidemics due to ritual endocannibalism, the various series iatrogenic diseases secondary to extractive growth hormone treatment or dura mater graft and the epidemics of variant Creutzfeldt-Jakob disease linked to dietary exposure to the agent of bovine spongiform encephalopathy. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of Q211 and K222 PRNP Polymorphic Variants in the Susceptibility of Goats to Oral Infection With Goat Bovine Spongiform Encephalopathy.

Science.gov (United States)

Aguilar-Calvo, Patricia; Fast, Christine; Tauscher, Kerstin; Espinosa, Juan-Carlos; Groschup, Martin H; Nadeem, Muhammad; Goldmann, Wilfred; Langeveld, Jan; Bossers, Alex; Andreoletti, Olivier; Torres, Juan-María

2015-08-15

The prion protein-encoding gene (PRNP) is one of the major determinants for scrapie occurrence in sheep and goats. However, its effect on bovine spongiform encephalopathy (BSE) transmission to goats is not clear. Goats harboring wild-type, R/Q211 or Q/K222 PRNP genotypes were orally inoculated with a goat-BSE isolate to assess their relative susceptibility to BSE infection. Goats were killed at different time points during the incubation period and after the onset of clinical signs, and their brains as well as several peripheral tissues were analyzed for the accumulation of pathological prion protein (PrP(Sc)) and prion infectivity by mouse bioassay. R/Q211 goats displayed delayed clinical signs compared with wild-type goats. Deposits of PrP(Sc) were detected only in brain, whereas infectivity was present in peripheral tissues too. In contrast, none of the Q/K222 goats showed any evidence of clinical prion disease. No PrP(Sc) accumulation was observed in their brains or peripheral tissues, but very low infectivity was detected in some tissues very long after inoculation (44-45 months). These results demonstrate that transmission of goat BSE is genotype dependent, and they highlight the pivotal protective effect of the K222 PRNP variant in the oral susceptibility of goats to BSE. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Nanocrystalline and ultrafine grain copper obtained by mechanical attrition

Directory of Open Access Journals (Sweden)

Rodolfo Rodríguez Baracaldo

2010-01-01

Full Text Available This article presents a method for the sample preparation and characterisation of bulk copper having grain size lower than 1 μm (ultra-fine grain and lower than 100 nm grain size (nanocrystalline. Copper is initially manufactured by a milling/alloying me- chanical method thereby obtaining a powder having a nanocrystalline structure which is then consolidated through a process of warm compaction at high pressure. Microstructural characterisation of bulk copper samples showed the evolution of grain size during all stages involved in obtaining it. The results led to determining the necessary conditions for achieving a wide range of grain sizes. Mechanical characterisation indicated an increase in microhardness to values of around 3.40 GPa for unconsolida- ted nanocrystalline powder. Compressivee strength was increased by reducing the grain size, thereby obtaining an elastic limit of 650 MPa for consolidated copper having a ~ 62 nm grain size.

Single and multi-layered core-shell structures based on ZnO nanorods obtained by aerosol assisted chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C.; Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx

2015-07-15

, materials absorptance determined from the total transmittance and reflectance spectra revealed a broader absorption interval including visible light, indicating potential uses of these nanostructures on solar energy appliances. - Graphical abstract: Display Omitted - Highlights: • Uniform ZnO nanorods (core)–metal oxide (shell) were obtained sequentially by AACVD. • Shells were structured of homogeneous single or multi-layered non-mixed metal oxides. • ZnO nanorod core was preserved during the shell synthesis. • Optical absorptance revealed visible interval absorption for FeO{sub x} shell samples. • Materials can be suitable for photocatalytic or photovoltaic applications.

Auditory bones obtained by synchrotron radiation computed tomography at SPring-8

International Nuclear Information System (INIS)

Hashimoto, E.; Sugiyama, H.; Maksimenko, A.

2005-01-01

A series tomograms and 3D reconstructions of the inner structure of the human auditory bone were obtained for the first time by employing absorption X-ray computed tomography using a synchrotron radiation. The experiment was performed at the very long transport channel beam line BL29XUL, where X-ray were available at 1000m from the source point. This method is great worth to making anatomically auditory structure observations without bursting the specimens. (author)

Osteogenic activity of titanium surfaces with hierarchical micro/nano-structures obtained by hydrofluoric acid treatment

Directory of Open Access Journals (Sweden)

Liang J

2017-02-01

Full Text Available Jianfei Liang,1,* Shanshan Xu,1,* Mingming Shen,2,* Bingkun Cheng,3 Yongfeng Li,4 Xiangwei Liu,1 Dongze Qin,1 Anuj Bellare,5 Liang Kong1 1State Key Laboratory of Military Stomatology & National Clinical Research Center for Oral Disease & Shaanxi Key Laboratory of Oral Diseases, Department of Oral and Maxillofacial Surgery, School of Stomatology, The Fourth Military Medical University, Xi’an, 2Department of Stomatology, Xinhua Hospital of Beijing, Beijing, 3Department of Oral and Maxillofacial Surgery, School of Stomatology, The Second Hospital of Hebei Medical University, Shijiazhuang, 4Department of Stomatology, Chinese PLA 532 Hospital, Huangshan, People’s Republic of China; 5Department of Orthopedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA *These authors contributed equally to this work Abstract: An easier method for constructing the hierarchical micro-/nano-structures on the surface of dental implants in the clinic is needed. In this study, three different titanium surfaces with microscale grooves (width 0.5–1, 1–1.5, and 1.5–2 µm and nanoscale nanoparticles (diameter 20–30, 30–50, and 50–100 nm, respectively were obtained by treatment with different concentrations of hydrofluoric acid (HF and at different etching times (1%, 3 min; 0.5%, 12 min; and 1.5%, 12 min, respectively; denoted as groups HF1, HF2, and HF3. The biological response to the three different titanium surfaces was evaluated by in vitro human bone marrow-derived mesenchymal stem cell (hBMMSC experiments and in vivo animal experiments. The results showed that cell adhesion, proliferation, alkaline phosphatase activity, and mineralization of hBMMSCs were increased in the HF3 group. After the different surface implants were inserted into the distal femurs of 40 rats, the bone–implant contact in groups HF1, HF2, and HF3 was 33.17%±2.2%, 33.82%±3.42%, and 41.04%±3.08%, respectively. Moreover, the maximal pullout

Use of Modular Approach to Obtain Molecular Glasses for Photonics: Triphenyl Moieties

OpenAIRE

Traskovskis, K; Kokars, V; Tokmakovs, A; Mihailovs, I; Rutkis, M

2012-01-01

Small molecular weight amorphous phase forming materials is a new emerging class of electro optical materials. While general principles linking molecular structure and material thermal and amorphous phase stability characteristics remain unresolved, molecular glasses have several considerable advantages such as relatively simple synthesis and purification, increased chromophore density and well defined structure. A wide spread strategy for obtaining molecular compounds capable of forming stab...

Sheep scrapie susceptibility-linked polymorphisms do not modulate the initial binding of cellular to disease-associated prion protein prior to conversion

NARCIS (Netherlands)

Rigter, A.; Bossers, A.

2005-01-01

Conversion of the host-encoded protease-sensitive cellular prion protein (PrPC) into the scrapie-associated protease-resistant isoform (PrPSc) of prion protein (PrP) is the central event in transmissible spongiform encephalopathies or prion diseases. Differences in transmissibility and

Localization of disease-related PrP in Danish patients with different subtypes of prion disease

DEFF Research Database (Denmark)

Bergström, A. L.; Heegaard, Peter M. H.; Dyrbye, H.

2009-01-01

Objective: The transmissible spongiform encephalopaties are characterized by vacuolization, neuronal loss, gliosis and deposition of a misfilded and Proteinase K resistant isoform of the prion protein (PrPSc) in the central nervous system. Methods, materials and patients: Paraffin-embedded tissue...

Gene expression profiling of mesenteric lymph nodes from sheep with natural scrapie

NARCIS (Netherlands)

Filali, H.; Martin-Burriel, I.; Harders, F.; Varona, L.; Hedman, C.; Mediano, D.R.; Monzón, M.; Bossers, A.; Badiola, J.J.

2014-01-01

Background - Prion diseases are characterized by the accumulation of the pathogenic PrPSc protein, mainly in the brain and the lymphoreticular system. Although prions multiply/accumulate in the lymph nodes without any detectable pathology, transcriptional changes in this tissue may reflect

Mesoporous silica obtained with methyltriethoxysilane as co-precursor in alkaline medium

Science.gov (United States)

Putz, Ana-Maria; Wang, Kunzhou; Len, Adél; Plocek, Jiri; Bezdicka, Petr; Kopitsa, Gennady P.; Khamova, Tamara V.; Ianăşi, Cătălin; Săcărescu, Liviu; Mitróová, Zuzana; Savii, Cecilia; Yan, Minhao; Almásy, László

2017-12-01

Mesoporous silica particles have been synthesized by sol-gel method from tetraethoxysilane (tetraethylorthosilicate, TEOS) and methyltriethoxysilane (MTES), in ethanol and water mixture, at different ratios of the of the silica precursors. Ammonia was used as catalyst at room temperature and hexadecyltrimethylammonium bromide (cetyltrimethylammonium bromide, CTAB) as the structure directing agent. Nitrogen sorption, X-ray diffraction and small-angle neutron scattering gave information on the evolution of the gel structure and pore morphologies in the function of MTES/TEOS molar ratio. Thermogravimetric and differential thermal analysis showed that with addition of MTES the exothermic peak indicating the oxidation of the low molecular weight organic fragments shift to higher temperature. A room-temperature, one-pot synthesis of MCM-41 type materials is presented, in which the variation of the MTES concentration allows to change the hydrophobicity, preserving the specific properties materials, like the ordered pore structure, large specific surface area and high porosity. Specifically, the obtained materials had cylindrical pores, specific surface areas up to 1101 m2/g and total pore volumes up to 0.473 cm3/g. The obtained mesoporous materials are susceptible for further functionalization to improve their selective uptake of guest species in drug delivery applications.

Uniaxially aligned ceramic nanofibers obtained by chemical mechanical processing

Energy Technology Data Exchange (ETDEWEB)

Tararam, R. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil); Foschini, C.R. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Bauru, Dept. de Eng. Mecanica, Av. Eng. Luiz Edmundo C. Coube 14-01, CEP 17033-360 Bauru, SP (Brazil); Destro, F.B. [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Simões, A.Z., E-mail: alezipo@yahoo.com [Univ Estadual Paulista – UNESP – Faculdade de Engenharia de Guaratinguetá, Guaratinguetá 12516-410, SP (Brazil); Longo, E.; Varela, J.A. [Univ Estadual Paulista – UNESP – Instituto de Química, Rua Prof. Francisco Degni n° 55, CEP 14800-900 Araraquara, SP (Brazil)

2014-08-01

For this study, we investigated a simple method to generate well aligned nanofibers over large areas using an organic polymer stretched over the substrate surface With this method, ZnO and CuO 3D parallel nanowire arrays were successfully prepared by calcinations of the polymer fibers. X-ray diffraction (XRD) analysis revealed that the copper oxide has a monoclinic structure while the zinc oxide has a hexagonal structure. Scanning electron microscopy (SEM) analysis showed ceramic nanofibers with an average diameter of 120 nm which were composed of small nanoparticles which are 10 nm in diameter. The ability to obtain uniaxially aligned nanofibers reveals a range of interesting properties with potential applications for sensors, catalysts and energy technologies.

Analysis of the fuel influence in obtaining HAp by combustion reaction

International Nuclear Information System (INIS)

Santos, T.L.; Leite, A.M.D.; Viana, K.M.S.

2016-01-01

The search for new materials for biomedical applications has led to investigation of the calcium phosphate bioceramics, and in particular hydroxyapatite (HAp), being a material similar to bone tissue, with excellent biocompatibility and high osteoconduction, enabling bone regeneration which allows the use at implants and prostheses. The synthesis of the nanometric HAp by combustion reaction enables obtaining the nanometric HAp with a more similar structure biological apatite as possible. This work aims to synthesize HAp by combustion reaction using two different routes of synthesis, first, using urea as fuel and the second using glycine, after this, evaluate the influence of fuels used in the microstructure of the hydroxyapatite obtained. The HAp obtained was characterized by: XRD, FTIR and SEM. Through analysis of the results, there is the synthesis conditions used that glycine has performed more favorable to obtaining HAp. (author)

Organophilic bentonites based on Argentinean and Brazilian bentonites: part 2: potential evaluation to obtain nanocomposites

Directory of Open Access Journals (Sweden)

L. B. Paiva

2012-12-01

Full Text Available This work describes the preparation of composites of polypropylene and organophilic bentonites based on Brazilian and Argentinean bentonites. During the processing of the samples in a twin screw microextruder, torque and pressures of the extruder were accompanied and the viscosity values were calculated. No significant changes in the torque, pressure and viscosity were found for composites prepared with different bentonites. The samples were characterized by XRD and TEM to evaluate the structure and dispersion of the organophilic bentonites. Composites with exfoliated, partially exfoliated and intercalated structures were obtained and correlations between the intrinsic properties of the sodium clays and organophilic bentonites and their influence on the composites were studied. The cation exchange capacity of the sodium bentonites and the swelling capacity of the organophilic bentonites were the most important properties to obtain exfoliated structures in composites. All bentonites showed the potential to obtain polymer nanocomposites, but the ones from Argentina displayed the best results.

Method of making quasi-grain boundary-free polycrystalline solar cell structure and solar cell structure obtained thereby

Science.gov (United States)

Gonzalez, Franklin N.; Neugroschel, Arnost

1984-02-14

A new solar cell structure is provided which will increase the efficiency of polycrystalline solar cells by suppressing or completely eliminating the recombination losses due to the presence of grain boundaries. This is achieved by avoiding the formation of the p-n junction (or other types of junctions) in the grain boundaries and by eliminating the grain boundaries from the active area of the cell. This basic concept can be applied to any polycrystalline material; however, it will be most beneficial for cost-effective materials having small grains, including thin film materials.

Emergence of two prion subtypes in ovine PrP transgenic mice infected with human MM2-cortical Creutzfeldt-Jakob disease prions.

Science.gov (United States)

Chapuis, Jérôme; Moudjou, Mohammed; Reine, Fabienne; Herzog, Laetitia; Jaumain, Emilie; Chapuis, Céline; Quadrio, Isabelle; Boulliat, Jacques; Perret-Liaudet, Armand; Dron, Michel; Laude, Hubert; Rezaei, Human; Béringue, Vincent

2016-02-05

Mammalian prions are proteinaceous pathogens responsible for a broad range of fatal neurodegenerative diseases in humans and animals. These diseases can occur spontaneously, such as Creutzfeldt-Jakob disease (CJD) in humans, or be acquired or inherited. Prions are primarily formed of macromolecular assemblies of the disease-associated prion protein PrP(Sc), a misfolded isoform of the host-encoded prion protein PrP(C). Within defined host-species, prions can exist as conformational variants or strains. Based on both the M/V polymorphism at codon 129 of PrP and the electrophoretic signature of PrP(Sc) in the brain, sporadic CJD is classified in different subtypes, which may encode different strains. A transmission barrier, the mechanism of which remains unknown, limits prion cross-species propagation. To adapt to the new host, prions have the capacity to 'mutate' conformationally, leading to the emergence of a variant with new biological properties. Here, we transmitted experimentally one rare subtype of human CJD, designated cortical MM2 (129 MM with type 2 PrP(Sc)), to transgenic mice overexpressing either human or the VRQ allele of ovine PrP(C). In marked contrast with the reported absence of transmission to knock-in mice expressing physiological levels of human PrP, this subtype transmitted faithfully to mice overexpressing human PrP, and exhibited unique strain features. Onto the ovine PrP sequence, the cortical MM2 subtype abruptly evolved on second passage, thereby allowing emergence of a pair of strain variants with distinct PrP(Sc) biochemical characteristics and differing tropism for the central and lymphoid tissues. These two strain components exhibited remarkably distinct replicative properties in cell-free amplification assay, allowing the 'physical' cloning of the minor, lymphotropic component, and subsequent isolation in ovine PrP mice and RK13 cells. Here, we provide in-depth assessment of the transmissibility and evolution of one rare subtype of

Structural and magnetic study of CoCr{sub 2}O{sub 4} thin films obtained by employing the sol-gel method

Energy Technology Data Exchange (ETDEWEB)

Del Toro, A.D.; Garcia, R.P.; Davila, Y.G.; Gomes, J.L.; Goncalves, L.P.; Hernandez, E.P. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

2016-07-01

Full text: In this work we made a study about the structural and magnetic properties of cobalt chromite. We obtained samples in a film format and also in chromite nanopowder. Both, the powder and films were fabricated by the sol-gel chemical method, the film were deposited by the spin coating technique followed by an appropriate heat treatment at 500 °C. The used substrate was glass based on silica and we studied the rotating speed parameter during deposition. The initial aim of the work was the study of the influence of rotating speed on the quality of cromite films. The crystallinity of samples was confirmed by diffraction X-ray (XRD). The lattice parameters were determined using the Rietveld method from which we calculate grain size of 8.6 nm. The scanning electron microscopy (SEM) showed granular films with good homogeneity and we observed the dependence of the rotating speed on the quality of the deposited films. The magnetic properties were measured using a vibrating sample magnetometer (VSM). For powder samples we obtained Curie temperature of 94 K, which is a phase transition from ferrimagnetic to paramagnetic. The applied magnetic field during in the characterization of the film was oriented parallel to the plane of the substrate and we observed a high coercivity. The Curie temperature value for the films was 93 K, similar to the powder samples. (author)

Deterministic Method for Obtaining Nominal and Uncertainty Models of CD Drives

DEFF Research Database (Denmark)

Vidal, Enrique Sanchez; Stoustrup, Jakob; Andersen, Palle

2002-01-01

In this paper a deterministic method for obtaining the nominal and uncertainty models of the focus loop in a CD-player is presented based on parameter identification and measurements in the focus loop of 12 actual CD drives that differ by having worst-case behaviors with respect to various...... properties. The method provides a systematic way to derive a nominal average model as well as a structures multiplicative input uncertainty model, and it is demonstrated how to apply mu-theory to design a controller based on the models obtained that meets certain robust performance criteria....

PULP OBTAINING METHOD FOR PACKAGE PRODUCTION

Directory of Open Access Journals (Sweden)

V. V. Kuzmich

2015-01-01

Full Text Available The paper presents a new method for obtaining pulp which is used for production of cardboard, paper and package while using carbon dioxide and hydrazine hydrate and neutral-sulfite  shive cooking. Output increase of  the desired product can be explained by reduction in destruction of plant raw material carbohydrates during its cooking process. Quality improvement of the desired product (improvement in bleaching and output is attributed to the fact that usage of carbon dioxide and hydrazine contributes to provision of polysaccharide chain resistance to destruction due to the presence of  end links having structure of metasaccharinic and aldonic acids.The author has developed a new method for pulp obtaining on the basis of the executed investigations  and literature data.  СО2 and hydrazine hydrate have been used for obtaining pulp. Method invention concerns pulp obtaining and it can be used for paper and cardboard package manufacturing in pulp and paper industry.The method is to be carried in the following way: pulp-containing plant raw material is loaded into an autoclave and then aqua solution of sodium monosulfite containing hydrazine hydrate that constitutes 4–5 % of absolute dry pulp-containing raw material mass with liquid module 1:6–1:8 is supplied into the autoclave. The autoclave is closed for operation under pressure and the solution is carbonated under pressure which constitutes 5–8 % of absolute dry plant raw material (shover. Temperature is subsequently raised up to 180 °С in the space of 2 hours and cooking is carried out in the course of 4 hours. Usage of  the proposed method for shover cooking makes it possible to reduce monosulfite cooking process and improve qualitative characteristics and output of the desired product.  In addition to above mentioned fact there is a possibility to improve bleaching and final product output. 

Structure of organometallic compounds obtained by plasma of titanium isopropoxide; Estructura de compuestos organometalicos obtenidos por plasma de isopropoxido de titanio

Energy Technology Data Exchange (ETDEWEB)

Arreola R, M. L.

2012-07-01

This work presents a study on the synthesis and characterization of organometallic compounds of titanium oxide obtained from glow discharges of titanium tetraisopropoxide (TTIP) and water on glass and polyethylene. The objective is the synthesis of titanium oxide particles which can be fixed on different supports for use in further studies of contaminants degradation in effluent streams. The synthesis was carried out by plasma in a glass tubular reactor of 750 cm{sup 3} and 15 cm length at 10{sup -1} mbar with power between 100 and 150 W during 2, 3 and 4 h. The precursors were TTIP and water vapor. TTIP is an organometallic compound composed of a central atom of Ti surrounded by 4 O atoms, which in turn are connected with chains of 3 C (propane s). The objective is the use of plasma collisions to separate the organic and inorganic phases of TTIP, so that both structure independently in a single material. The result was the formation of white titanium oxide powder composed with agglomerates of spherical particles with average diameter between 160 and 452 nm adhered to small films. The agglomerates have a tendency to change from film to particles with the energy applied to the synthesis. The study of the chemical structure showed a great presence of O{sub 2}-Ti-O{sub 2} (Ti surrounded by O) which can be found in most titanium oxides. Other chemical groups belonging to the organic phase were C=C=C, C=C=O and C{sub 2}-C-Ch appearing from the dehydrogenation of TTIP, which can be a possible precursor of this reactions kind. The structural superficial analyses showed that the atomic composition varies according to type of substrate used. The greatest content of Ti was obtained on glass substrates. However, the synthesis conditions had not evident effect in the participation of chemical states found in the inorganic phase. The crystalline studies indicated that the material is amorphous, although the de convoluted X-ray spectra showed that the synthesized titanium oxides

Mapping of possible prion protein self interaction domains using peptide arrays

NARCIS (Netherlands)

Rigter, A.; Langeveld, J.P.M.; Timmers-Parohi, D.; Jacobs, J.G.; Moonen, P.L.J.M.; Bossers, A.

2007-01-01

Background The common event in transmissible spongiform encephalopathies (TSEs) or prion diseases is the conversion of host-encoded protease sensitive cellular prion protein (PrPC) into strain dependent isoforms of scrapie associated protease resistant isoform (PrPSc) of prion protein (PrP). These

Scrapie susceptibility-linked polymorphisms modulate the in vitro conversion of sheep prion protein to protease-resistant forms

NARCIS (Netherlands)

Bossers, A.; Belt, P.B.G.M.; Raymond, G.J.; Caughey, B.; Vries, de R.; Smits, M.

1997-01-01

Prion diseases are natural transmissible neurodegenerative disorders in humans and animals. They are characterized by the accumulation of a protease-resistant scrapie-associated prion protein (PrPSc) of the host-encoded cellular prion protein (PrPC) mainly in the central nervous system.

Adult human microglia secrete cytokines when exposed to neurotoxic prion protein peptide: no intermediary role for prostaglandin E2

NARCIS (Netherlands)

Veerhuis, Robert; Hoozemans, Jeroen J. M.; Janssen, Ingrid; Boshuizen, Ronald S.; Langeveld, Jan P. M.; Eikelenboom, Piet

2002-01-01

Prion diseases are characterized by accumulation of protease resistant isoforms of prion protein (termed PrP(SC)), glial activation and neurodegeneration. The time course of PrP deposition, appearance of activated microglia, and of neuronal apoptosis in experimentally-induced prion disease suggests

A novel seven-octapeptide repeat insertion in the prion protein gene (PRNP) in a Dutch pedigree with Gerstmann-Sträussler-Scheinker disease phenotype: comparison with similar cases from the literature

NARCIS (Netherlands)

Jansen, Casper; Voet, Willem; Head, Mark W.; Parchi, Piero; Yull, Helen; Verrips, Aad; Wesseling, Pieter; Meulstee, Jan; Baas, Frank; van Gool, Willem A.; Ironside, James W.; Rozemuller, Annemieke J. M.

2011-01-01

Human prion diseases can be sporadic, inherited or acquired by infection and show considerable phenotypic heterogeneity. We describe the clinical, histopathological and pathological prion protein (PrP(Sc)) characteristics of a Dutch family with a novel 7-octapeptide repeat insertion (7-OPRI) in

Functional nanostructured titanium nitride films obtained by sputtering magnetron

International Nuclear Information System (INIS)

Sanchez, O.; Hernandez-Velez, M.; Navas, D.; Auger, M.A.; Baldonedo, J.L.; Sanz, R.; Pirota, K.R.; Vazquez, M.

2006-01-01

Development of new methods in the formation of hollow structures, in particular, nanotubes and nanocages are currently generating a great interest as a consequence of the growing relevance of these nanostructures on many technological fields, ranging from optoelectronics to biotechnology. In this work, we report the formation of titanium nitride (TiN) nanotubes and nanohills via reactive sputtering magnetron processes. Anodic Alumina Membranes (AAM) were used as template substrates to grow the TiN nanostructures. The AAM were obtained through electrochemical anodization processes by using oxalic acid solutions as electrolytes. The nanotubes were produced at temperatures below 100 deg. C, and using a pure titanium (99.995%) sputtering target and nitrogen as reactive gas. The obtained TiN thin films showed surface morphologies adjusted to pore diameter and interpore distance of the substrates, as well as ordered arrays of nanotubes or nanohills depending on the sputtering and template conditions. High Resolution Scanning Electron Microscopy (HRSEM) was used to elucidate both the surface order and morphology of the different grown nanostructures. The crystalline structure of the samples was examined using X-ray Diffraction (XRD) patterns and their qualitative chemical composition by using X-ray Energy Dispersive Spectroscopy (XEDS) in a scanning electron microscopy

Detection of prions in the faeces of sheep naturally infected with classical scrapie

Directory of Open Access Journals (Sweden)

Terry Linda A

2011-05-01

Full Text Available Abstract Classical scrapie is a naturally transmitted prion disease of sheep and goats. Contaminated environments may contribute to the spread of disease and evidence from animal models has implicated urine, blood, saliva, placenta and faeces as possible sources of the infection. Here we sought to determine whether sheep naturally infected with classical scrapie shed prions in their faeces. We used serial protein misfolding cyclic amplification (sPMCA along with two extraction methods to examine faeces from sheep during both the clinical and preclinical phases of the disease and showed amplification of PrPSc in 7 of 15 and 14 of 14 sheep respectively. However PrPSc was not amplified from the faeces of 25 sheep not exposed to scrapie. These data represent the first demonstration of prion shedding in faeces from a naturally infected host and thus a likely source of prion contamination in the environment.

The structure study of boron carbonitride films obtained by use of trimethylamine borane complex

CERN Document Server

Kosinova, M L; Fainer, N I; Maximovski, E A; Kuznetsov, F A

2001-01-01

Diffraction of synchrotron radiation (SR) was used to investigate crystalline structure and phase composition of thin films (1500-5000 A) of boron carbonitride. These films were synthesized by plasma-enhanced chemical vapor deposition using nontraditional volatile single source precursor trimethylamine borane complex (CH sub 3) sub 3 N centre dot BH sub 3 and its mixture with ammonia. The effect of the gas ratio and substrate temperature on chemical and phase composition as well as the structure of the films were investigated. The XRD peculiarities of texture films and ways of increasing sensibility of measurements were considered. A possibility of the information density rise of the thin film XRD was shown due to application of different methods for recording diffraction patterns.

Structural studies of calcium phosphate doped with titanium and zirconium obtained by high-energy mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Silva, C C; Sombra, A S B [Telecommunications and Materials Science and Engineering Laboratory (LOCEM), Physics Department, Federal University of Ceara, Campus do Pii, Postal Code 6030, 60455-760, Fortaleza-Ceara (Brazil)], E-mail: sombra@fisica.ufc.br

2009-12-15

In this paper, we present a new variation of the solid-state procedure on the synthesis of bioceramics with titanium (CapTi) and zirconium (CapZr), considering that zirconium (ZrO{sub 2}) and titanium oxide (TiO{sub 2}) are strengthening agents, due to their superb force and fracture toughness. The high efficiency of the calcination process opens a new way of producing commercial amounts of nanocrystalline bioceramics. In this work, a new variation of the solid-state procedure method was used to produce nanocrystalline powders of titanium and zirconium, using two different experimental chemical routes: CapTi: Ca(H{sub 2}PO{sub 4}){sub 2}+TiO{sub 2} and CapZr: Ca(H{sub 2}PO{sub 4}){sub 2}+ZrO{sub 2}. The powders were submitted to calcination processes (CapTic and CapZrc) at 800, 900 and 1000 deg. C. The calcium titanium phosphate phase, CaTi{sub 4}P{sub 6}O{sub 24}, was obtained in the CapTic reaction and the calcium zirconium phosphate, CaZr{sub 4}P{sub 6}O{sub 24}, was obtained in the CapZrc reaction. The obtained ceramics were characterized by x-ray powder diffraction (XRD), infrared (IR) spectroscopy, Raman scattering spectroscopy (RSS) and scanning electron microscopy (SEM) analysis. This method was compared with the milling process (CapTim and CapZrm), where in the last process the melting is not necessary and the powder obtained is nanocrystalline. The calcium titanium phosphate phase, CaTi{sub 4}P{sub 6}O{sub 24}, was obtained in the reaction CapTim, but in CapZrm the formation of any calcium phosphate phase even after 15 h of dry mechanical alloying was not observed.

Use of stem sliced from in vitro plants of papaya (hybrid IBP 42-99 by obtained callus with embryogenic structure

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Jorge Gallardo Colina

2004-10-01

Full Text Available Inside in vitro propagation via, the somatic embriogenesis offers possibilities of obtaining top volumes of production in a minor period of time and a lower cost, which are a method potentially more efficient than the regeneration via organogenesis. In papaya the somatic embryogenesis could have developed from zigotic embryos and axis hipocotilos, nevertheless in case of the hybrids these methods cannot be used and it becomes necessary to develop it from a somatic fabric, without link with the sexual reproduction. This work chased as main objective Evaluated the use of in vitro plants stem sections of the Carica papaya IBP 42-99 hybrid for the formation of callus with embryogenic structures. As plant material were use in vitro plants of the papaya hybrid IBP 42-99. For it there took sections of different parts of the stem from the meristem up to the base of the in vitro plants, was use the culture medium Nitsh and Nitsh supplemented with 1.5 mg.l-1 of 6-BAP and 1.5 mg.l-1 of AIA. It was achieved to obtain callus from the stem sections with the culture medium used, nevertheless, in the treatments where used cylinders inside 1.0 cm from the apex down, the best results were achieved. The use of in vitro plants stem sections as explant for the formation of callus in this vegetable species it opens new possibilities for his in vitro propagation, specially in case of resultant hybrids of genetic improvement programs. Key words: apexes, Carica papaya, callogenesis, somatic embryogenesis

Putting prions into focus: application of single molecule detection to the diagnosis of prion diseases.

Science.gov (United States)

Giese, A; Bieschke, J; Eigen, M; Kretzschmar, H A

2000-01-01

Prion diseases are characterized by the cerebral deposition of an aggregated pathological isoform of the prion protein (PrP(Sc)) which constitutes the principal component of the transmissible agent termed prion. In order to develop a highly sensitive method for the detection of PrP(Sc) aggregates in biological samples such as cerebrospinal fluid (CSF), we used a method based on Fluorescence Correlation Spectroscopy (FCS), a technique which allows detection of single fluorescently labeled molecules in solution. Within the FCS setup, fluorescent photons emitted by molecules passing an open volume element defined by the beam of an excitation laser focussed into a diffraction-limited spot are imaged confocally onto a single photon counting detector. Aggregates of PrP(Sc) could be labeled by co-aggregation of probe molecules such as monomeric recombinant PrP or PrP-specific antibodies tagged with a fluorescent dye. In addition to slow diffusion, labeled aggregates are characterized by high fluorescence intensity, which allows detection and quantification by analysis of fluorescence intensity distribution. To improve detection of rare target particles, the accessible volume element was increased by scanning for intensely fluorescent targets (SIFT). To further improve sensitivity and specificity, two different probes were used simultaneously in a two-color setup. In a diagnostic model system of CSF spiked with purified prion rods, dual-color SIFT was more sensitive than Western blot analysis. In addition, a PrP(Sc)-specific signal was also detected in a number of CSF samples derived from CJD patients but not in controls.

PrP mRNA and protein expression in brain and PrP(c) in CSF in Creutzfeldt-Jakob disease MM1 and VV2.

Science.gov (United States)

Llorens, Franc; Ansoleaga, Belén; Garcia-Esparcia, Paula; Zafar, Saima; Grau-Rivera, Oriol; López-González, Irene; Blanco, Rosi; Carmona, Margarita; Yagüe, Jordi; Nos, Carlos; Del Río, José Antonio; Gelpí, Ellen; Zerr, Inga; Ferrer, Isidre

2013-01-01

Creutzfeldt-Jakob disease (CJD) is a heterogenic neurodegenerative disorder associated with abnormal post-translational processing of cellular prion protein (PrP(c)). CJD displays distinctive clinical and pathological features which correlate with the genotype at the codon 129 (methionine or valine: M or V respectively) in the prion protein gene and with size of the protease-resistant core of the abnormal prion protein PrP(sc) (type 1: 20/21 kDa and type 2: 19 kDa). MM1 and VV2 are the most common sporadic CJD (sCJD) subtypes. PrP mRNA expression levels in the frontal cortex and cerebellum are reduced in sCJD in a form subtype-dependent. Total PrP protein levels and PrP(sc) levels in the frontal cortex and cerebellum accumulate differentially in sCJD MM1 and sCJD VV2 with no relation between PrP(sc) deposition and spongiform degeneration and neuron loss, but with microgliosis, and IL6 and TNF-α response. In the CSF, reduced PrP(c), the only form present in this compartment, occurs in sCJD MM1 and VV2. PrP mRNA expression is also reduced in the frontal cortex in advanced stages of Alzheimer disease, Lewy body disease, progressive supranuclear palsy, and frontotemporal lobe degeneration, but PrP(c) levels in brain varies from one disease to another. Reduced PrP(c) levels in CSF correlate with PrP mRNA expression in brain, which in turn reflects severity of degeneration in sCJD.

PrP(ST), a soluble, protease resistant and truncated PrP form features in the pathogenesis of a genetic prion disease.

Science.gov (United States)

Friedman-Levi, Yael; Mizrahi, Michal; Frid, Kati; Binyamin, Orli; Gabizon, Ruth

2013-01-01

While the conversion of PrP(C) into PrP(Sc) in the transmissible form of prion disease requires a preexisting PrP(Sc) seed, in genetic prion disease accumulation of disease related PrP could be associated with biochemical and metabolic modifications resulting from the designated PrP mutation. To investigate this possibility, we looked into the time related changes of PrP proteins in the brains of TgMHu2ME199K/wt mice, a line modeling for heterozygous genetic prion disease linked to the E200K PrP mutation. We found that while oligomeric entities of mutant E199KPrP exist at all ages, aggregates of wt PrP in the same brains presented only in advanced disease, indicating a late onset conversion process. We also show that most PK resistant PrP in TgMHu2ME199K mice is soluble and truncated (PrP(ST)), a pathogenic form never before associated with prion disease. We next looked into brain samples from E200K patients and found that both PK resistant PrPs, PrP(ST) as in TgMHu2ME199K mice, and "classical" PrP(Sc) as in infectious prion diseases, coincide in the patient's post mortem brains. We hypothesize that aberrant metabolism of mutant PrPs may result in the formation of previously unknown forms of the prion protein and that these may be central for the fatal outcome of the genetic prion condition.

PrP(ST, a soluble, protease resistant and truncated PrP form features in the pathogenesis of a genetic prion disease.

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Yael Friedman-Levi

Full Text Available While the conversion of PrP(C into PrP(Sc in the transmissible form of prion disease requires a preexisting PrP(Sc seed, in genetic prion disease accumulation of disease related PrP could be associated with biochemical and metabolic modifications resulting from the designated PrP mutation. To investigate this possibility, we looked into the time related changes of PrP proteins in the brains of TgMHu2ME199K/wt mice, a line modeling for heterozygous genetic prion disease linked to the E200K PrP mutation. We found that while oligomeric entities of mutant E199KPrP exist at all ages, aggregates of wt PrP in the same brains presented only in advanced disease, indicating a late onset conversion process. We also show that most PK resistant PrP in TgMHu2ME199K mice is soluble and truncated (PrP(ST, a pathogenic form never before associated with prion disease. We next looked into brain samples from E200K patients and found that both PK resistant PrPs, PrP(ST as in TgMHu2ME199K mice, and "classical" PrP(Sc as in infectious prion diseases, coincide in the patient's post mortem brains. We hypothesize that aberrant metabolism of mutant PrPs may result in the formation of previously unknown forms of the prion protein and that these may be central for the fatal outcome of the genetic prion condition.

Experimental Characterization of Aluminum-Based Hybrid Composites Obtained Through Powder Metallurgy

Science.gov (United States)

Marcu, D. F.; Buzatu, M.; Ghica, V. G.; Petrescu, M. I.; Popescu, G.; Niculescu, F.; Iacob, G.

2018-06-01

The paper presents some experimental results concerning fabrication through powder metallurgy (P/M) of aluminum-based hybrid composites - Al/Al2O3/Gr. In order to understand the mechanisms that occur during the P/M processes of obtaining Al/Al2O3/Gr composite, we correlated the physical characteristics with their micro-structural characteristics. The characterization was performed using analysis techniques specific for P/M process, SEM-EDS and XRD analyses. Micro-structural characterization of the composites has revealed fairly uniform distribution this resulting in good properties of the final composite material.

Single session imaging of cerebellum at 7 Tesla: obtaining structure and function of multiple motor subsystems in individual subjects.

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Melissa A Batson

Full Text Available The recent increase in the use of high field MR systems is accompanied by a demand for acquisition techniques and coil systems that can take advantage of increased power and accuracy without being susceptible to increased noise. Physical location and anatomical complexity of targeted regions must be considered when attempting to image deeper structures with small nuclei and/or complex cytoarchitechtonics (i.e. small microvasculature and deep nuclei, such as the brainstem and the cerebellum (Cb. Once these obstacles are overcome, the concomitant increase in signal strength at higher field strength should allow for faster acquisition of MR images. Here we show that it is technically feasible to quickly and accurately detect blood oxygen level dependent (BOLD signal changes and obtain anatomical images of Cb at high spatial resolutions in individual subjects at 7 Tesla in a single one-hour session. Images were obtained using two high-density multi-element surface coils (32 channels in total placed beneath the head at the level of Cb, two channel transmission, and three-dimensional sensitivity encoded (3D, SENSE acquisitions to investigate sensorimotor activations in Cb. Two classic sensorimotor tasks were used to detect Cb activations. BOLD signal changes during motor activity resulted in concentrated clusters of activity within the Cb lobules associated with each task, observed consistently and independently in each subject: Oculomotor vermis (VI/VII and CrusI/II for pro- and anti-saccades; ipsilateral hemispheres IV-VI for finger tapping; and topographical separation of eye- and hand- activations in hemispheres VI and VIIb/VIII. Though fast temporal resolution was not attempted here, these functional patches of highly specific BOLD signal changes may reflect small-scale shunting of blood in the microvasculature of Cb. The observed improvements in acquisition time and signal detection are ideal for individualized investigations such as

Lyotropic liquid crystal based on zinc oxide nanoparticles obtained by microwave solvothermal synthesis

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Omelchenko, M.M., E-mail: momelchenko@chem.uw.edu.pl [Department of Chemistry, Warsaw University, Al. Zwirki i Wigury 101, 02-089, Warsaw (Poland); Wojnarowicz, J. [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, Warsaw, 01-142 (Poland); Salamonczyk, M. [Department of Chemistry, Warsaw University, Al. Zwirki i Wigury 101, 02-089, Warsaw (Poland); Lojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Sokolowska 29/37, Warsaw, 01-142 (Poland)

2017-05-01

Abstract: The ZnO nanoparticles, obtained by microwave solvothermal synthesis, were used for the liquid crystal phase preparation. The structure of the material was investigated by X-ray diffraction (XRD), helium pycnometry, specific surface area (SSA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM). The stability of aqueous suspensions was monitored by Multiple Light Scattering (MLS) technique and the average agglomerate size in suspensions was obtained by dynamic light scattering (DLS) technique. The lyotropic columnar hexagonal phase was formed by doping ZnO nanoparticles into the cetylpiridinium chloride/water/hexanol system. The structure of this phase was confirmed by x-ray diffraction. The luminescent properties of the LC phase were compared with properties of ZnO nanoparticles isolated in solution and analogues lyotropic system without nanoparticles.

Fracture properties of high-strength concrete obtained by direct modification of structure

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Solodkyy Serhiy

2017-01-01

Full Text Available High-strength concrete is effectively used worldwide in the last three decades, but it is more brittle in comparison with normal strength concretes. Partial substitution of cement in concrete by active mineral additives and usage of chemical admixture of plasticizing and air-entraining action can considerably change their fracture properties. The obtained results show that the increase of the fracture properties is observed in concretes modified with chemical admixtures incorporating mineral additives such as zeolite and limestone due to consolidation of the concrete microstructure. Densification takes place as a result of limiting the amount of calcium hydroxide (CH due to its reaction with active silica included in the zeolite and the formation of larger amounts of hydrated calcium silicates of tobermorite type as well as calcium hydroaluminate and hydrocarboaluminate with the simultaneous adsorption modification of hydrated products by chemical admixtures.

Disease-associated prion protein detected in lymphoid tissues from pigs challenged with the agent of chronic wasting disease

Science.gov (United States)

Aims: Chronic wasting disease (CWD) is a naturally-occurring, fatal neurodegenerative disease of cervids. We previously demonstrated that disease-associated prion protein (PrPSc) can be detected in the brain and retina from pigs challenged intracranially or orally with the CWD agent. In that study,...

Characterisation of new monoclonal antibodies reacting with prions from both human and animal brain tissues

DEFF Research Database (Denmark)

Hvass, Henriette Cordes; Bergström, Ann-Louise; Ohm, Jakob

2008-01-01

spongiform encephalopathy (bovine brain), scrapie (ovine brain) and experimental scrapie in hamster and in mice. The antibodies were also used for PET-blotting in which PrPSc blotted from brain tissue sections onto a nitrocellulose membrane is visualized with antibodies after protease and denaturant...

Prions in Variably Protease-Sensitive Prionopathy: An Update

NARCIS (Netherlands)

Zou, W.Q.; Gambetti, P.; Xiao, X.; Yuan, J.; Langeveld, J.P.M.; Pirisinu, L.

2013-01-01

Human prion diseases, including sporadic, familial, and acquired forms such as Creutzfeldt-Jakob disease (CJD), are caused by prions in which an abnormal prion protein (PrPSc) derived from its normal cellular isoform (PrPC) is the only known component. The recently-identified variably

Structure and Absolute Configuration of Jurassic Polyketide-Derived Spiroborate Pigments Obtained from Microgram Quantities.

Science.gov (United States)

Wolkenstein, Klaus; Sun, Han; Falk, Heinz; Griesinger, Christian

2015-10-28

Complete structural elucidation of natural products is often challenging due to structural complexity and limited availability. This is true for present-day secondary metabolites, but even more for exceptionally preserved secondary metabolites of ancient organisms that potentially provide insights into the evolutionary history of natural products. Here, we report the full structure and absolute configuration of the borolithochromes, enigmatic boron-containing pigments from a Jurassic putative red alga, from samples of less than 50 μg using microcryoprobe NMR, circular dichroism spectroscopy, and density functional theory calculations and reveal their polyketide origin. The pigments are identified as spiroborates with two pentacyclic sec-butyl-trihydroxy-methyl-benzo[gh]tetraphen-one ligands and less-substituted derivatives. The configuration of the sec-butyl group is found to be (S). Because the exceptional benzo[gh]tetraphene scaffold is otherwise only observed in the recently discovered polyketide clostrubin from a present-day Clostridium bacterium, the Jurassic borolithochromes now can be unambiguously linked to the modern polyketide, providing evidence that the fossil pigments are almost originally preserved secondary metabolites and suggesting that the pigments in fact may have been produced by an ancient bacterium. The borolithochromes differ fundamentally from previously described boronated polyketides and represent the first boronated aromatic polyketides found so far. Our results demonstrate the potential of microcryoprobe NMR in the analysis of previously little-explored secondary metabolites from ancient organisms and reveal the evolutionary significance of clostrubin-type polyketides.

Indium doped zinc oxide thin films obtained by electrodeposition

International Nuclear Information System (INIS)

Machado, G.; Guerra, D.N.; Leinen, D.; Ramos-Barrado, J.R.; Marotti, R.E.; Dalchiele, E.A.

2005-01-01

Indium doped ZnO thin films were obtained by co-electrodeposition (precursor and dopant) from aqueous solution. XRD analysis showed typical patterns of the hexagonal ZnO structure for both doped and undoped films. No diffraction peaks of any other structure such as In 2 O 3 or In(OH) 3 were found. The incorporation of In into the ZnO film was verified by both EDS and XPS measurements. The bandgap energy of the films varied from 3.27 eV to 3.42 eV, increasing with the In concentration in the solution. This dependence was stronger for the less cathodic potentials. The incorporation of In into the film occurs as both, an In donor state in the ZnO grains and as an amorphous In 2 O 3 at the grain boundaries

Diagnostic value of sectional images obtained by emission tomography

International Nuclear Information System (INIS)

Roucayrol, J.C.

1981-01-01

It is now possible to obtain clear images of the various planes in and around a structure with ultra-sounds (echotomography), X-rays (computerized tomography) and recently, gamma-rays from radioactive substances (emission tomography). Axial transverse tomography, which is described here, is to conventional scintigraphy what CT scan is to radiography. It provides images of any structure capable of concentrating sufficiently a radioactive substance administered intravenously. These images are perpendicular to the longitudinal axis of the body. As shown by examples in the liver, lungs and myocardium, lesions which had passed unnoticed with other exploratory techniques can now be demonstrated, and the location, shape and extension of known lesions can be more accurately assessed. Emission tomography already has its place in modern diagnostic procedures side by side with echotomography and CT scan [fr

Obtaining porous silicon suitable for sensor technology using MacEtch nonelectrolytic etching

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Iatsunskyi I. R.

2013-12-01

Full Text Available The author suggests to use the etching method MacEtch (metal-assisted chemical etching for production of micro- and nanostructures of porous silicon. The paper presents research results on the morphology structures obtained at different parameters of deposition and etching processes. The research has shown that, depending on the parameters of deposition of silver particles and silicon wafers etching, the obtained surface morphology may be different. There may be both individual crater-like pores and developed porous or macroporous surface. These results indicate that the MacEtch etching is a promising method for obtaining micro-porous silicon nanostructures suitable for effective use in gas sensors and biological object sensors.

Structure of Suasselkä Postglacial Fault in northern Finland obtained by analysis of ambient seismic noise

Science.gov (United States)

Afonin, Nikita; Kozlovskaya, Elena

2016-04-01

Understanding inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of ambient seismic noise recorded by the temporary DAFNE array in northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä post-glacial fault (SPGF) that was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised the area of about 20 to 100 km and consisted of 8 short-period and 4 broad-band 3-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September, 2011-May, 2013. Recordings of the array have being analyzed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä Gold Mine. As a result, we found several dozens of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate correspondent surface wave dispersion curves. After that S-wave velocity models were obtained as a result of dispersion curves inversion using Geopsy software. The results suggest that the area of

Characterization of Titanium Oxide Nanoparticles Obtained by Hydrolysis Reaction of Ethylene Glycol Solution of Alkoxide

OpenAIRE

Naofumi Uekawa; Naoya Endo; Keisuke Ishii; Takashi Kojima; Kazuyuki Kakegawa

2012-01-01

Transparent and stable sols of titanium oxide nanoparticles were obtained by heating a mixture of ethylene glycol solution of titanium tetraisopropoxide (TIP) and a NH3 aqueous solution at 368 K for 24 h. The concentration of NH3 aqueous solution affected the structure of the obtained titanium oxide nanoparticles. For NH3 aqueous solution concentrations higher than 0.2 mol/L, a mixture of anatase TiO2 nanoparticles and layered titanic acid nanoparticles was obtained. The obtained sol was very...

Magnetically diluted semi-conductor of SnO_2- Fe obtained by controlled precipitation

International Nuclear Information System (INIS)

Cajas, P.C.; Munoz, R.; Rodriguez-Paez, J.E.

2014-01-01

Solid solutions were synthesized SnO_2 doped with 5% and 8 mol% Fe by the controlled precipitation method. The particles size was obtained of ∼12 nm with heath treatment 450 °C. The presence of iron in the structure is evidenced by Raman spectroscopy The crystallite size we obtained with the results of XRD, and particle size by MET, it was concluded that the nanoparticles obtained were monocrystalline. The particles were characterized magnetically, for the powders doped to 8% Fe was determined ferromagnetic behavior at 5K, with a tendency superparamagnetic and paramagnetic at a temperature of 300K. (author)

Microstructural characterization of the geopolymer obtained from iron-rich metakaolin

International Nuclear Information System (INIS)

Vassalo, Erica Antunes de S.; Aguilar, Maria Teresa P.; Gumieri, Adriana Guerra

2014-01-01

Geopolymer is a material derived from precursors rich in SiO_2 and Al_2O_3, activated in an alkaline solution by means of a polymerization process. In this process, units of tetrahedral aluminosilicate structures are organized in repetitions that share oxygen. One of the precursors most commonly used to obtain geopolymer is metakaolin. Recent studies have reported iron enhancement in a partial replacement of the aluminium present in metakaolin. This paper presents the microstructural characterization and analysis of a geopolymer obtained by means of the activation of iron-rich metakaolin with sodium hydroxide at 12, 15 and 18 mol, both at room temperature and in an oven at 85±3°C. The geopolymers obtained were classified and analysed using X-ray fluorescence testing (EDX-720), a scanning electron microscope (SEM) and a Fourier transform infrared spectroscopy (FTIR). The results enabled an assessment of their physical-chemical and microstructural characteristics, as well as their reactive potential. (author)

Porous materials based on foaming solutions obtained from industrial waste

Science.gov (United States)

Starostina, I. V.; Antipova, A. N.; Ovcharova, I. V.; Starostina, Yu L.

2018-03-01

This study analyzes foam concrete production efficiency. Research has shown the possibility of using a newly-designed protein-based foaming agent to produce porous materials using gypsum and cement binders. The protein foaming agent is obtained by alkaline hydrolysis of a raw mixture consisting of industrial waste in an electromagnetic field. The mixture consists of spent biomass of the Aspergillus niger fungus and dust from burning furnaces used in cement production. Varying the content of the foaming agent allows obtaining gypsum binder-based foam concretes with the density of 200-500 kg/m3 and compressive strength of 0.1-1.0 MPa, which can be used for thermal and sound insulation of building interiors. Cement binders were used to obtain structural and thermal insulation materials with the density of 300-950 kg/m3 and compressive strength of 0.9-9.0 MPa. The maximum operating temperature of cement-based foam concretes is 500°C because it provides the shrinkage of less than 2%.

Semisynthetic prion protein (PrP) variants carrying glycan mimics at position 181 and 197 do not form fibrils† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc02719b Click here for additional data file.

Science.gov (United States)

Araman, Can; Thompson, Robert E.; Wang, Siyao; Hackl, Stefanie; Payne, Richard J.

2017-01-01

The prion protein (PrP) is an N-glycosylated protein attached to the outer leaflet of eukaryotic cell membranes via a glycosylphosphatidylinositol (GPI) anchor. Different prion strains have distinct glycosylation patterns and the extent of glycosylation of potentially pathogenic misfolded prion protein (PrPSc) has a major impact on several prion-related diseases (transmissible spongiform encephalopathies, TSEs). Based on these findings it is hypothesized that posttranslational modifications (PTMs) of PrP influence conversion of cellular prion protein (PrPC) into PrPSc and, as such, modified PrP variants are critical tools needed to investigate the impact of PTMs on the pathogenesis of TSEs. Here we report a semisynthetic approach to generate PrP variants modified with monodisperse polyethyleneglycol (PEG) units as mimics of N-glycans. Incorporating PEG at glycosylation sites 181 and 197 in PrP induced only small changes to the secondary structure when compared to unmodified, wildtype PrP. More importantly, in vitro aggregation was abrogated for all PEGylated PrP variants under conditions at which wildtype PrP aggregated. Furthermore, the addition of PEGylated PrP as low as 10 mol% to wildtype PrP completely blocked aggregation. A similar effect was observed for synthetic PEGylated PrP segments comprising amino acids 179–231 alone if these were added to wildtype PrP in aggregation assays. This behavior raises the question if large N-glycans interfere with aggregation in vivo and if PEGylated PrP peptides could serve as potential therapeutics. PMID:28989689

Generation of human scFvs antibodies recognizing a prion protein epitope expressed on the surface of human lymphoblastoid cells

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Imperiale Valentina

2007-07-01

Full Text Available Abstract Background A hallmark of prion disease is the transformation of normal cellular prion protein (PrPc into an infectious disease-associated isoform, (PrPsc. Anti-prion protein monoclonal antibodies are invaluable for structure-function studies of PrP molecules. Furthermore recent in vitro and in vivo studies indicate that anti-PrP monoclonal antibodies can prevent the incorporation of PrPc into propagating prions. In the present article, we show two new human phage antibodies, isolated on recombinant hamster prion protein (rHaPrP. Results We adopted an antibody phage display strategy to isolate specific human antibodies directed towards rHaPrP which has been used as a bait for panning the synthetic ETH-2 antibody phage library. Two phage antibodies clones named MA3.B4 and MA3.G3 were isolated and characterized under genetic biochemical and immunocytochemical aspects. The clones were found to recognize the prion protein in ELISA studies. In flow-cytometry studies, these human single chain Fragment variable (scFv phage-antibodies show a well defined pattern of reactivity on human lymphoblastoid and myeloid cells. Conclusion Sequence analysis of the gene encoding for the antibody fragments and antigen recognition patterns determined by flow-cytometry analysis indicate that the isolated scFvs recognize novel epitopes in the PrPc molecule. These new anti PrPc human antibodies are unique reagents for prion protein detection and may represent a biologic platform to develop new reagents to treat PrPsc associated disease.

Determining the relative susceptibility of four prion protein genotypes to atypical scrapie

Science.gov (United States)

Atypical scrapie is a sheep prion (PrPSc) disease whose epidemiology is consistent with a sporadic origin and is associated with specific polymorphisms of the normal cellular prion protein (PrPC). We describe a mass spectrometry-based method of detecting and quantifying the polymorphisms of sheep P...

Prion protein amyloidosis with divergent phenotype associated with two novel nonsense mutations in PRNP

NARCIS (Netherlands)

Jansen, Casper; Parchi, Piero; Capellari, Sabina; Vermeij, Ad J.; Corrado, Patrizia; Baas, Frank; Strammiello, Rosaria; van Gool, Willem A.; van Swieten, John C.; Rozemuller, Annemieke J. M.

2010-01-01

Stop codon mutations in the gene encoding the prion protein (PRNP) are very rare and have thus far only been described in two patients with prion protein cerebral amyloid angiopathy (PrP-CAA). In this report, we describe the clinical, histopathological and pathological prion protein (PrPSc)

Polyacrolein with microspherical structure obtained by radiation-Initiation and base catalysis

International Nuclear Information System (INIS)

Usanmaz, A.; Dogan, R.D.

1990-01-01

Acrolein was polymerized by radiation and base catalyzed condensation. Radiation polymerization was carried in bulk form under vacuum and air atmosphere at several temperatures. The conversion reached close to 100 %, and polymers were free flowing white powders up to 5 % conversion at -15degC, up to 80 % at higher temperatures and up to 10 % in air atmosphere polymerization. Radiation polymerization from aqueous solutions of various pH and from acetone solutions gave white powder polymers with limiting conversions ranging from 10 to 18 % depending on the solution type or pH. The conversion at pH between 1, 5 to 8 gave minimum pH of 5 to 6. The base catalyzed polymerization at pH of 9 to 12 gave white powdered polymers changing to a yellowish colour with increase of pH. The limiting conversion was about 14 %. The nature of repeating units in the polymer chains was studied by IR and thermogravimetry. The polymers contained different repeating units randomly, and the aldehyde content was higher for radiation polymerization than base catalyzed polymerization. A scanning electron microscope investigation showed the powder polymers to have microspherical structures of various size depending on polymerization conditions. (author)

Computational Calculation Of The Ionization Energies Of The Human Prion Protein By The Coarse-grain Method

Science.gov (United States)

Lyu, Justin; Andrianarijaona, V. M.

2016-05-01

The causes of the misfolding of prion protein -i.e. the transformation of PrPC to PrPSc - have not been clearly elucidated. Many studies have focused on identifying possible chemical conditions, such as pH, temperature and chemical denaturation, that may trigger the pathological transformation of prion proteins (Weiwei Tao, Gwonchan Yoon, Penghui Cao, `` β-sheet-like formation during the mechanical unfolding of prion protein'', The Journal of Chemical Physics, 2015, 143, 125101). Here, we attempt to calculate the ionization energies of the prion protein, which will be able to shed light onto the possible causes of the misfolding. We plan on using the coarse-grain method which allows for a more feasible calculation time by means of approximation. We believe that by being able to approximate the ionization potential, particularly that of the regions known to form stable β-strands of the PrPSc form, the possible sources of denaturation, be it chemical or mechanical, may be narrowed down.

Extraneural manifestations of prion infection in GPI-anchorless transgenic mice

International Nuclear Information System (INIS)

Lee, Andrew M.; Paulsson, Johan F.; Cruite, Justin; Andaya, Abegail A.; Trifilo, Matthew J.; Oldstone, Michael B.A.

2011-01-01

Earlier studies indicated that transgenic (tg) mice engineered to express prion protein (PrP) lacking the glycophosphatidylinositol (GPI -/- ) membrane anchor formed abnormal proteinase-resistant prion (PrPsc) amyloid deposits in their brains and hearts when infected with the RML strain of murine scrapie. In contrast, RML scrapie infection of normal mice with a GPI-anchored PrP did not deposit amyloid with PrPsc in the brain or the heart. Here we report that scrapie-infected GPI -/- PrP tg mice also deposit PrP and transmissible infectious material in the gut, kidneys, and islets of Langerhans. Similar to previously reported amyloid deposits in the brain and heart, amyloid deposits were found in the gut; however, no amyloid deposited in the islets. By high-resolution electron microscopy, we show PrP is located primarily in α cells and also β cells. Islets contain abundant insulin and there is no abnormality in glucose metabolism in infected GPI -/- PrP tg mice.

Unaltered Prion Pathogenesis in a Mouse Model of High-Fat Diet-Induced Insulin Resistance.

Directory of Open Access Journals (Sweden)

Caihong Zhu

Full Text Available Epidemiological, clinical, and experimental animal studies suggest a strong correlation between insulin resistance and Alzheimer's disease. In fact, type-2 diabetes is considered an important risk factor of developing Alzheimer's disease. In addition, impaired insulin signaling in the Alzheimer's disease brain may promote Aβ production, impair Aβ clearance and induce tau hyperphosphorylation, thereby leading to deterioration of the disease. The pathological prion protein, PrPSc, deposits in the form of extracellular aggregates and leads to dementia, raising the question as to whether prion pathogenesis may also be affected by insulin resistance. We therefore established high-fat diet-induced insulin resistance in tga20 mice, which overexpress the prion protein. We then inoculated the insulin-resistant mice with prions. We found that insulin resistance in tga20 mice did not affect prion disease progression, PrPSc deposition, astrogliosis or microglial activation, and had no effect on survival. Our study demonstrates that in a mouse model, insulin resistance does not significantly contribute to prion pathogenesis.

Multiple-walled BN nanotubes obtained with a mechanical alloying technique

International Nuclear Information System (INIS)

Rosas, G.; Sistos, J.; Ascencio, J.A.; Medina, A.; Perez, R.

2005-01-01

An experimental method to obtain multiple-walled nanotubes of BN using low energy is presented. The method is based on the use of mechanical alloying techniques with elemental boron powders and nitrogen gas mixed in an autoclave at room temperature. The chemical and structural characteristics of the multiple-walled nanotubes were obtained using different techniques, such as X-ray diffraction, transmission electron microscopy, EELS microanalysis, high-resolution electron microscopy images and theoretical simulations based on the multisliced approach of the electron diffraction theory. This investigation clearly illustrates the production of multiple-wall BN nanotubes at room temperature. These results open up a new kind of synthesis method with low expense and important perspectives for use in large-quantity production. (orig.)

SERS spectrum of gallic acid obtained from a modified silver colloid

Science.gov (United States)

Garrido, C.; Diaz-Fleming, G.; Campos-Vallette, M. M.

2016-06-01

Two different crystals of the gallic acid were microscopically separated from a p.a. commercial product. The Raman spectra analysis allowed distinguishing monomeric and dimeric structures. The vibrational wave numbers were computed using DFT quantum chemical calculations. The data obtained from wave number calculations are used to assign vibrational bands obtained in the Raman spectrum. The dimer, characterized as ellagic acid, involves the carboxyl and hydroxyl moieties. The Raman spectrum in water solution of each species is dominated by the monomeric form. A low negatively charged Ag colloid allowed obtain to the best of our knowledge, the first surface enhanced Raman scattering (SERS) spectrum of the gallic acid. The possible electrophilic attacking sites of the title molecule are identified using MEP surface plot study and the orientation of the analyte on the metal surface is proposed tilted to the surface.

Raman light scattering in nanoporous carbon obtained from carbides of silicon and titanium

International Nuclear Information System (INIS)

Danishevskij, A.M.; Smorgonskaya, Eh.A.; Gordeev, S.K.; Grechinskaya, A.V.

2001-01-01

The Raman spectra in nanoporous carbon obtained through the chemical reaction from the polycrystal α-SiC and TiC are studied. It is shown that the spectra have a multicomponent character differentiating the considered group of materials from graphites and disordered carbon structures. The series of low-frequency modes is registered. The anisotropy and dispersion effects are identified. The results testify to the cluster structure of nanoporous carbon and dimensional quantization of electron and vibrational spectra in the carbon nanoclusters. The fine fragments of curved or fractures graphed sheets are the basic structural elements of nanoclusters in the porous skeleton. The presence of fragments close by structure to the tense cubic or hexagonal diamond is also notes [ru

Robustness Analyses of Timber Structures

DEFF Research Database (Denmark)

Kirkegaard, Poul Henning; Sørensen, John Dalsgaard; Hald, Frederik

2013-01-01

The robustness of structural systems has obtained a renewed interest arising from a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures, many mo...... with respect to robustness of timber structures and will discuss the consequences of such robustness issues related to the future development of timber structures.......The robustness of structural systems has obtained a renewed interest arising from a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures, many...... modern building codes consider the need for the robustness of structures and provide strategies and methods to obtain robustness. Therefore, a structural engineer may take necessary steps to design robust structures that are insensitive to accidental circumstances. The present paper summaries issues...

Novel Antimicrobial Titanium Dioxide Nanotubes Obtained through a Combination of Atomic Layer Deposition and Electrospinning Technologies

Science.gov (United States)

Patiño, Cristian; Galotto, María Jose; Palma, Juan Luis; Alburquenque, Daniela

2018-01-01

The search for new antimicrobial substances has increased in recent years. Antimicrobial nanostructures are one of the most promising alternatives. In this work, titanium dioxide nanotubes were obtained by an atomic layer deposition (ALD) process over electrospun polyvinyl alcohol nanofibers (PVN) at different temperatures with the purpose of obtaining antimicrobial nanostructures with a high specific area. Electrospinning and ALD parameters were studied in order to obtain PVN with smallest diameter and highest deposition rate, respectively. Chamber temperature was a key factor during ALD process and an appropriate titanium dioxide deposition performance was achieved at 200 °C. Subsequently, thermal and morphological analysis by SEM and TEM microscopies revealed hollow nanotubes were obtained after calcination process at 600 °C. This temperature allowed complete polymer removal and influenced the resulting anatase crystallographic structure of titanium dioxide that positively affected their antimicrobial activities. X-ray analysis confirmed the change of titanium dioxide crystallographic structure from amorphous phase of deposited PVN to anatase crystalline structure of nanotubes. These new nanostructures with very large surface areas resulted in interesting antimicrobial properties against Gram-positive and Gram-negative bacteria. Titanium dioxide nanotubes presented the highest activity against Escherichia coli with 5 log cycles reduction at 200 μg/mL concentration. PMID:29495318

Lithium storage into carbonaceous materials obtained from sugarcane bagasse

International Nuclear Information System (INIS)

Matsubara, Elaine Y.; Lala, Stella M.; Rosolen, Jose Mauricio

2010-01-01

Carbonaceous materials with different structures are prepared by carbonization of sugarcane bagasse. Depending on carbonization conditions, it is possible to obtain soot rich in flakes or in honeycomb-shaped micrometric particles, whose concentration has large influence on lithium storage into electrodes. The soot rich in honeycomb-shaped particles provides the best electrochemical performance, with a reversible specific capacity of 310 mAh g -1 . The results suggest that the sugarcane bagasse can be potentially used in the design of anodic materials for lithium ion batteries. (author)

High-energy radiation processing, a smart approach to obtain PVP-graft-AA nanogels

International Nuclear Information System (INIS)

Grimaldi, N.; Sabatino, M.A.; Przybytniak, G.; Kaluska, I.; Bondì, M.L.; Bulone, D.; Alessi, S.; Spadaro, G.; Dispenza, C.

2014-01-01

Poly(N-vinylpyrrolidone)-grafted-acrylic acid biocompatible nanogels (NGs) were prepared using an exiting industrial-type electron accelerator and setups, starting from semi-dilute aqueous solutions of a commercial PVP and the acrylic acid monomer. As a result, NGs with tunable size and structure can be obtained quantitatively. Sterility was also imparted at the integrated dose absorbed. The chemical structure of the NGs produced was confirmed through Fourier Transformer Infrared Spectroscopy (FT-IR). The molecular and physico-chemical properties of NGs, such as the hydrodynamic dimensions and surface charge densities, for various polymer and monomer concentrations in the irradiated solutions, are discussed here. - Highlights: • Aqueous solutions of PVP and AA were irradiated by industrial electron accelerator. • NGs with different physico-chemical and molecular properties can be obtained. • Carboxyl-functionalized NGs produced are promising building blocks for bio-devices

Prion disease tempo determined by host-dependent substrate reduction

NARCIS (Netherlands)

Mays, C.E.; Kim, C.; Haldiman, T.; Merwe, v.d. J.; Lau, A.; Yang, J.; Grams, J.; Bari, Di M.A.; Nonno, R.; Telling, G.C.; Kong, Q.; Langeveld, J.P.M.; McKenzie, D.; Westaway, D.; Safar, J.G.

2014-01-01

The symptoms of prion infection can take years or decades to manifest following the initial exposure. Molecular markers of prion disease include accumulation of the misfolded prion protein (PrPSc), which is derived from its cellular precursor (PrPC), as well as downregulation of the PrP-like Shadoo

Co-existence of scrapie prion protein types 1 and 2 in sporadic Creutzfeldt-Jakob disease: its effect on the phenotype and prion-type characteristics

NARCIS (Netherlands)

Cali, I.; Castellani, R.; Alshekhlee, A.; Cohen, Y.; Blevins, J.; Yuan, J.; Langeveld, J.P.M.; Parchi, P.; Safar, J.G.; Zou, W.Q.; Gambetti, P.

2009-01-01

Five phenotypically distinct subtypes have been identified in sporadic Creutzfeldt-Jakob disease (sCJD), based on the methionine/valine polymorphic genotype of codon 129 of the prion protein (PrP) gene and the presence of either one of the two protease K-resistant scrapie prion protein (PrPSc) types

Molecular features related to HIV integrase inhibition obtained from structure- and ligand-based approaches.

Directory of Open Access Journals (Sweden)

Luciana L de Carvalho

Full Text Available Among several biological targets to treat AIDS, HIV integrase is a promising enzyme that can be employed to develop new anti-HIV agents. The aim of this work is to propose a mechanistic interpretation of HIV-1 integrase inhibition and to rationalize the molecular features related to the binding affinity of studied ligands. A set of 79 HIV-1 integrase inhibitors and its relationship with biological activity are investigated employing 2D and 3D QSAR models, docking analysis and DFT studies. Analyses of docking poses and frontier molecular orbitals revealed important features on the main ligand-receptor interactions. 2D and 3D models presenting good internal consistency, predictive power and stability were obtained in all cases. Significant correlation coefficients (r(2 = 0.908 and q(2= 0.643 for 2D model; r(2= 0.904 and q(2= 0.719 for 3D model were obtained, indicating the potential of these models for untested compounds. The generated holograms and contribution maps revealed important molecular requirements to HIV-1 IN inhibition and several evidences for molecular modifications. The final models along with information resulting from molecular orbitals, 2D contribution and 3D contour maps should be useful in the design of new inhibitors with increased potency and selectivity within the chemical diversity of the data.

Fluid-structure interaction of submerged structures

International Nuclear Information System (INIS)

Tang, H.T.; Becker, E.B.; Taylor, L.M.

1979-01-01

The purpose of the paper is to investigate fluid-structure interaction (FSI) of submerged structures in a confined fluid-structure system. Our particular interest is the load experienced by a rigid submerged structure subject to a pressure excitation in a fluid domain bounded by a structure which is either flexible or rigid. The objective is to see whether the load experienced by the submerged structure will be influenced by its confinement conditions. This investigation is intended to provide insight into the characteristics of FSI and answer the question as to whether one can obtain FSI independent data by constructing a small scale rigid submerged structure inside a flexible fluid-structure system. (orig.)

The structure and thermal properties of novel polyurethane/organoclay nanocomposites obtained by pre-polymerization

Czech Academy of Sciences Publication Activity Database

Pavličević, J.; Špírková, Milena; Jovičić, M.; Bera, O.; Poreba, Rafal; Budinski-Simendic, J.

2013-01-01

Roč. 45, č. 1 (2013), s. 232-238 ISSN 1359-8368 R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : layered structures * polymer–matrix composites (PMCs) * thermal properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.602, year: 2013

Obtaining of inulin acetate

OpenAIRE

Khusenov, Arslonnazar; Rakhmanberdiev, Gappar; Rakhimov, Dilshod; Khalikov, Muzaffar

2014-01-01

In the article first obtained inulin ester inulin acetate, by etherification of inulin with acetic anhydride has been exposed. Obtained product has been studied using elementary analysis and IR spectroscopy.

MeCrAl coatings obtained by arc PVD and pack cementation processes on nickel base superalloys

International Nuclear Information System (INIS)

Swadzba, L.; Maciejny, A.; Formanek, B.; Mendala, B.

1997-01-01

The paper presents the results of researches on obtaining and structure of high temperature resistance coatings on superalloys. The coatings were deposited on nickel and nickel base superalloys in two stages. During the first stage, the NiCr and NiCrHf coatings were obtained by arc-PVD method. Basic technology, bias, arc current, rotation, parameters of deposition of NiCr and MeCrHf coatings were defined. The high efficiency of deposition of both single and two sources was observed. The targets were made by vacuum melting and machining. An influence of targets chemical composition on coating structure and chemical coatings composition was described. The second stage was made by pack cementation HTLA (high temperature low activity) on 1323 K chromoaluminizing process. These arc-PVD and diffusion (pack cementation) connected processes permitted to obtain MeCrAl and MeCrAlHf type of coatings. The morphology, structure and microchemical composition were characterized by scanning electron microscopy, X-ray microanalysis, energy dispersive X-ray spectroscopy and X-ray diffraction methods. (orig.)

Robustness Evaluation of Timber Structures

DEFF Research Database (Denmark)

Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

2009-01-01

Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure.......Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure....

Neuropathological and biochemical criteria to identify acquired Creutzfeldt-Jakob disease among presumed sporadic cases.

Science.gov (United States)

Kobayashi, Atsushi; Parchi, Piero; Yamada, Masahito; Mohri, Shirou; Kitamoto, Tetsuyuki

2016-06-01

As an experimental model of acquired Creutzfeldt-Jakob disease (CJD), we performed transmission studies of sporadic CJD using knock-in mice expressing human prion protein (PrP). In this model, the inoculation of the sporadic CJD strain V2 into animals homozygous for methionine at polymorphic codon 129 (129 M/M) of the PRNP gene produced quite distinctive neuropathological and biochemical features, that is, widespread kuru plaques and intermediate type abnormal PrP (PrP(Sc) ). Interestingly, this distinctive combination of molecular and pathological features has been, to date, observed in acquired CJD but not in sporadic CJD. Assuming that these distinctive phenotypic traits are specific for acquired CJD, we revisited the literature and found two cases showing widespread kuru plaques despite the 129 M/M genotype, in a neurosurgeon and in a patient with a medical history of neurosurgery without dura mater grafting. By Western blot analysis of brain homogenates, we revealed the intermediate type of PrP(Sc) in both cases. Furthermore, transmission properties of brain extracts from these two cases were indistinguishable from those of a subgroup of dura mater graft-associated iatrogenic CJD caused by infection with the sporadic CJD strain V2. These data strongly suggest that the two atypical CJD cases, previously thought to represent sporadic CJD, very likely acquired the disease through exposure to prion-contaminated brain tissues. Thus, we propose that the distinctive combination of 129 M/M genotype, kuru plaques, and intermediate type PrP(Sc) , represents a reliable criterion for the identification of acquired CJD cases among presumed sporadic cases. © 2015 Japanese Society of Neuropathology.

Transmission of chronic wasting disease identifies a prion strain causing cachexia and heart infection in hamsters.

Directory of Open Access Journals (Sweden)

Richard A Bessen

Full Text Available Chronic wasting disease (CWD is an emerging prion disease of free-ranging and captive cervids in North America. In this study we established a rodent model for CWD in Syrian golden hamsters that resemble key features of the disease in cervids including cachexia and infection of cardiac muscle. Following one to three serial passages of CWD from white-tailed deer into transgenic mice expressing the hamster prion protein gene, CWD was subsequently passaged into Syrian golden hamsters. In one passage line there were preclinical changes in locomotor activity and a loss of body mass prior to onset of subtle neurological symptoms around 340 days. The clinical symptoms included a prominent wasting disease, similar to cachexia, with a prolonged duration. Other features of CWD in hamsters that were similar to cervid CWD included the brain distribution of the disease-specific isoform of the prion protein, PrP(Sc, prion infection of the central and peripheral neuroendocrine system, and PrP(Sc deposition in cardiac muscle. There was also prominent PrP(Sc deposition in the nasal mucosa on the edge of the olfactory sensory epithelium with the lumen of the nasal airway that could have implications for CWD shedding into nasal secretions and disease transmission. Since the mechanism of wasting disease in prion diseases is unknown this hamster CWD model could provide a means to investigate the physiological basis of cachexia, which we propose is due to a prion-induced endocrinopathy. This prion disease phenotype has not been described in hamsters and we designate it as the 'wasting' or WST strain of hamster CWD.

The obtaining of iron acetate from processed iron comprising catalyst of ammonia synthesis

International Nuclear Information System (INIS)

Mansurov, M.M.; Lugovenko, A.N.; Mirzoeva, M.M.

1993-01-01

Present article is devoted to obtaining of iron acetate from processed iron comprising catalyst of ammonia synthesis. The method of synthesis of iron acetate from processed iron comprising catalyst of ammonia synthesis was elaborated. The structure of complex was determined.

Electronic and magnetic structure of BaCoO2 as obtained from LSDA and LSDA+U calculations

KAUST Repository

Nazir, Safdar; Zhu, Zhiyong; Pulikkotil, Jiji Thomas Joseph; Schwingenschlö gl, Udo

2011-01-01

Density functional theory is used to study the structural, electronic, and magnetic properties of BaCoO2. Structural relaxation for different collinear magnetic configurations points to a remarkable magneto-elastic coupling in BaCoO2. Although we

Corrosion resistance of «tube – tubesheet» weld joint obtained by friction welding

Directory of Open Access Journals (Sweden)

RIZVANOV Rif Garifovich

2017-08-01

Full Text Available Shell-and-tube heat exchangers are widely applied for implementation of various processes at ventures of fuel and energy complex. Cost of production and reliability of heat exchangers of this type is to a wide extent determined by corresponding characteristics of tube bundle, «tube – tubesheet» is its typical joint in particular when welding operations are used in order to attach tubes to tubesheet in addition to expansion. When manufacturing such equipment of heat-resistant chrome-bearing or chromium-molybdenum steels including steel 15H5M, the process of fixed joint manufacturing gets significantly more complicated and costly due to the necessity to use thermal treatment before, during and after welding (this problem is particularly applicable for manufacturing of large-size equipment. One of the options to exclude thermal treatment from manufacturing process is to use «non-arc» welding methods – laser welding, explosion welding as well as friction welding. Use of each of the welding methods mentioned above during production of heat-exchange equipment has its process challenges and peculiarities. This article gives a comparative analysis of weld structure and distribution of electrode potentials of welded joints and parent metal of the joints simulating welding of tube to tubesheet of steel 15H5M using the following welding methods: shielded manual arc welding, tungsten-arc inert-gas welding and friction welding. Comparative analysis of macro- and microstructures of specific zones of the studied welded joints showed that the joints produced by arc welding methods do not exhibit evident inhomogeneity of the structure after application of thermal treatment which is explained by the correctness of thermal treatment. Joints obtained via friction welding are characterized by structural inhomogeneity of the welded joint zone metal microstructure. The ultra-fine-grained structure obtained as a result of friction welding makes it possible to

Synthesis and chemical and structural characterization of hydroxyapatite obtained from eggshell and tricalcium phosphate

OpenAIRE

Arboleda, Alejandro; Franco, Manuel; Caicedo, Julio; Tirado, Liliana; Goyes, Clara

2016-01-01

The eggshell is a common residue that is usually discarded without giving any use to it. In this paper the results obtained from a proposed procedure to get hydroxyapatite (HA) from eggshell are shown. The HA is a calcium phosphate which has been widely used as implant material due to the close similarity of its composition with the inorganic phase of natural bone. HA generally has a high cost and it is presented as micro and nanostructured bioceramics; the last one is a promising option for ...

Optical and structural characterization of nickel oxide-based thin films obtained by chemical bath deposition

International Nuclear Information System (INIS)

Vidales-Hurtado, M.A.; Mendoza-Galvan, A.

2008-01-01

Nickel oxide-based thin films were obtained using the chemical bath deposition method on glass and silicon substrates. The precursor solution used was a mixture of nickel nitrate, urea, and deionized water. Molar concentration of nickel (0.3-1.0 M), deposition time, and immersing cycles were considered as deposition variables. Infrared spectroscopy and X-ray diffraction data reveal that all as-deposited films correspond to the transparent turbostratic phase α(II)-Ni(OH) 2 . However, the rate of deposition depends on nickel content in the solution. After annealing in air at temperatures above of 300 deg. C, the films are transformed to the NiO phase and show a grey/black color. In these films, scanning electron microscopy images show aggregates of thin stacked sheets on their surface, such aggregates can be easily removed leaving only a thin NiO layer of about 30 nm adhered firmly to the substrate, regardless of nickel concentration in the solution and deposition time. In order to obtain thicker NiO films with good optical properties a procedure is developed performing several immersing-annealing cycles

EXPLOSIVE COMPACTION OF CLAD GRAPHITE POWDERS AND OBTAINING OF COATINGS ON THEIR BASE

Energy Technology Data Exchange (ETDEWEB)

A. B. PEIKRISHIVILI; ET AL

2000-11-01

In order to consolidate graphite based powders and in order to obtain coatings with density values near to the theoretical ones clad graphite powders of the C{sub graphite} - Ni (C{sub g} - Ni) compositions were explosively compacted under different loading conditions. Theoretical calculations revealed that for assessing the stress-deformed state of C{sub g} - Ni compositions and computing the normal and tangent stress components (when V{sub D} < C{sub longitudinal} and V{sub D} < C{sub transversal}) it is recommended to apply the dynamic problem's solution model while the pressure impulse P = f(x) is being uniformly spread with constant rate along the boundary of a semi-infinite elastic body. The results of our experiments showed that it is possible to obtain high dense coatings from C{sub g}-Ni compositions bonded by an intermediate layer to the substrate material. The structure and properties of the coatings depends on the intensity of the shock loading and temperature. The effect of the shock loading conditions (temperature, loading intensity) on the structure, properties and structure/properties relationships for the C{sub g} - Ni coatings are discussed.

A Fluorescent Oligothiophene-Bis-Triazine ligand interacts with PrP fibrils and detects SDS-resistant oligomers in human prion diseases.

Science.gov (United States)

Imberdis, Thibaut; Ayrolles-Torro, Adeline; Duarte Rodrigues, Alysson; Torrent, Joan; Alvarez-Martinez, Maria Teresa; Kovacs, Gabor G; Verdier, Jean-Michel; Robitzer, Mike; Perrier, Véronique

2016-01-26

Prion diseases are characterized by the accumulation in the central nervous system of an abnormally folded isoform of the prion protein, named PrP(Sc). Aggregation of PrP(Sc) into oligomers and fibrils is critically involved in the pathogenesis of prion diseases. Oligomers are supposed to be the key neurotoxic agents in prion disease, so modulation of prion aggregation pathways with small molecules can be a valuable strategy for studying prion pathogenicity and for developing new diagnostic and therapeutic approaches. We previously identified thienyl pyrimidine compounds that induce SDS-resistant PrP(Sc) (rSDS-PrP(Sc)) oligomers in prion-infected samples. Due to the low effective doses of the thienyl pyrimidine hits, we synthesized a quaterthiophene-bis-triazine compound, called MR100 to better evaluate their diagnostic and therapeutic potentials. This molecule exhibits a powerful activity inducing rSDS-PrP(Sc) oligomers at nanomolar concentrations in prion-infected cells. Fluorescence interaction studies of MR100 with mouse PrP fibrils showed substantial modification of the spectrum, and the interaction was confirmed in vitro by production of rSDS-oligomer species upon incubation of MR100 with fibrils in SDS-PAGE gel. We further explored whether MR100 compound has a potential to be used in the diagnosis of prion diseases. Our results showed that: (i) MR100 can detect rSDS-oligomers in prion-infected brain homogenates of various species, including human samples from CJD patients; (ii) A protocol, called "Rapid Centrifugation Assay" (RCA), was developed based on MR100 property of inducing rSDS-PrP(Sc) oligomers only in prion-infected samples, and avoiding the protease digestion step. RCA allows the detection of both PK-sensitive and PK-resistant PrP(Sc) species in rodents samples but also from patients with different CJD forms (sporadic and new variant); (iii) A correlation could be established between the amount of rSDS-PrP(Sc) oligomers revealed by MR100 and the

Study of TiO{sub 2} nanomembranes obtained by an induction heated MOCVD reactor

Energy Technology Data Exchange (ETDEWEB)

Crisbasan, A., E-mail: andreea.crisbasan@yahoo.com [NANOFORM Group, ICB, Université de Bourgogne, BP 47 870, 21078 Dijon (France); Chaumont, D. [NANOFORM Group, ICB, Université de Bourgogne, BP 47 870, 21078 Dijon (France); Sacilotti, M. [NANOFORM Group, ICB, Université de Bourgogne, BP 47 870, 21078 Dijon (France); Departamento de Fisica – Universidade Federal de Pernambuco, Recife (Brazil); Crisan, A.; Lazar, A.M.; Ciobanu, I. [Science and Materials Engineering Faculty, University of Transilvania, Brasov (Romania); Lacroute, Y.; Chassagnon, R. [Université de Bourgogne, BP 47 870, 21078 Dijon (France)

2015-12-15

Highlights: • The TiO{sub 2} structures have been obtained by the MOCVD technique using ferrocene, cobalt layer (annealed at 350 °C) and Ti(OC{sub 3}H{sub 7}){sub 4}. • The TiO{sub 2} growth at 550 °C, during 20 min on the cobalt layer (obtained by electron beam evaporation method) on soda-lime glass has as result TiO{sub 2} nanomembranes. • The TiO{sub 2} nanomembranes grow on the cobalt nuclei. • The TiO{sub 2} nanomembranes are polycrystalline, built from TiO{sub 2} anatase and rutile crystals. - Abstract: Nanostructures of TiO{sub 2} were grown using the metal oxide chemical vapor deposition (MOCVD) technique. The procedure used induction heating on a graphite susceptor. This specific feature and the use of cobalt and ferrocene catalysts resulted in nanomembranes never obtained by common MOCVD reactors. The present study discusses the preparation of TiO{sub 2} nanomembranes and the dependence of nanomembrane structure and morphology on growth parameters.

Differential effects of divalent cations on elk prion protein fibril formation and stability

Science.gov (United States)

Misfolding of the normally folded prion protein of mammals (PrPC) into infectious fibrils causes a variety of different diseases, from scrapie in sheep to bovine spongiform encephalopathy in cattle to chronic wasting disease (CWD) in deer and elk. The misfolded form of PrPC, termed PrPSc, or in this...

Temporal resolution of misfolded prion protein transport, accumulation, glial activation, and neuronal death in the retinas of mice inoculated with scrapie

Science.gov (United States)

Currently, there is a lack of pathologic landmarks to describe the progression of prion disease in vivo. The goal of this work was to determine the temporal relationship between the transport of misfolded prion protein from the brain to the retina, the accumulation of PrPSc in the retina, the respon...

Comparative aspects of bovine spongiform encephalopathy isolates found in the U.S.

Science.gov (United States)

Bovine spongiform encephalopathy (BSE) can be subdivided into at least three groups: classical, H-type, and L-type. The latter 2 designations are based on higher or lower apparent molecular mass profiles of the unglycosylated PrP**Sc band in a western blot and are collectively referred to as atypica...

Sensitive and specific detection of classical scrapie prions in the brain of goats by real-time quaking-induced conversion

Science.gov (United States)

The real-time quaking-induced conversion (RT-QuIC) is a rapid, specific, and sensitive prion seeding activity detection assay that uses recombinant prion protein (rPrPSen) to detect sub-infectious levels of the abnormal isoforms of the prion protein (PrPSc). Although RT-QuIC has been successfully us...

MM2-Thalamic Creutzfeldt-Jacob Disease: Neuropathological, Biochemical and Transmission Studies Identify a Distinctive Prion Strain

NARCIS (Netherlands)

Moda, F.; Suardi, S.; Fede, Di G.; Indaco, A.; Limido, L.; Vimercati, C.; Ruggerone, M.; Campagnani, I.; Langeveld, J.P.M.; Terruzzi, A.; Brambilla, A.; Zerbi, P.; Fociani, P.; Bishop, T.; Will, G.W.; Manson, J.C.; Giaccone, G.; Tagliavini, F.

2012-01-01

In CreutzfeldtJakob disease (CJD), molecular typing based on the size of the protease resistant core of the disease-associated prion protein (PrPSc) and the M/V polymorphism at codon 129 of the PRNP gene correlates with the clinico-pathologic subtypes. Approximately 95% of the sporadic 129MM CJD

Structural behavior of reinforced concrete structures at high temperatures

International Nuclear Information System (INIS)

Yamazaki, N.; Yamazaki, M.; Mochida, T.; Mutoh, A.; Miyashita, T.; Ueda, M.; Hasegawa, T.; Sugiyama, K.; Hirakawa, K.; Kikuchi, R.; Hiramoto, M.; Saito, K.

1995-01-01

To establish a method to predict the behavior of reinforced concrete structures subjected simultaneously to high temperatures and external loads, this paper presents the results obtained in several series of tests carried out recently in Japan. This paper reports on the material properties of concrete and steel bars under high temperatures. It also considers the heat transfer properties of thick concrete walls under transient high temperatures, and the structural behavior of reinforced concrete beams subjected to high temperatures. In the tests, data up to 800 C were obtained for use in developing a computational method to estimate the non-linear behavior of reinforced concrete structures exposed to high temperatures. (orig.)

Trivalent dopants on ZnO semiconductor obtained by mechanical milling

Energy Technology Data Exchange (ETDEWEB)

Damonte, L.C., E-mail: damonte@fisica.unlp.edu.a [Dto. De Fisica, UNLP, IFLP-CONICET, C.C.67 (1900) La Plata (Argentina); Dto. De Fisica Aplicada, Universidad Politecnica de Valencia, Valencia (Spain); Donderis, V. [Dto. De Ingenieria Electrica, Universidad Politecnica de Valencia, Cami de Vera s/n, 46071 Valencia (Spain); Hernandez-Fenollosa, M.A. [Dto. De Fisica Aplicada, Universidad Politecnica de Valencia, Valencia (Spain)

2009-08-26

Al-doped ZnO powders were obtained by mechanical milling. This n-type oxide material is of interest for application in electronic devices as solar cells. The incorporation of the metal dopant into the ZnO wurtzite structure has been verified by X-ray diffraction, positron annihilation spectroscopy and optical analysis. The optical reflection measurements were strongly affected by the Al incorporation. The positron annihilation spectroscopy constituted an adequate probe to sense the cation substitution in the doped semiconductor.

Trivalent dopants on ZnO semiconductor obtained by mechanical milling

International Nuclear Information System (INIS)

Damonte, L.C.; Donderis, V.; Hernandez-Fenollosa, M.A.

2009-01-01

Al-doped ZnO powders were obtained by mechanical milling. This n-type oxide material is of interest for application in electronic devices as solar cells. The incorporation of the metal dopant into the ZnO wurtzite structure has been verified by X-ray diffraction, positron annihilation spectroscopy and optical analysis. The optical reflection measurements were strongly affected by the Al incorporation. The positron annihilation spectroscopy constituted an adequate probe to sense the cation substitution in the doped semiconductor.

Trained nurses can obtain satisfactory bone marrow aspirates and trephine biopsies.

Science.gov (United States)

Lawson, S; Aston, S; Baker, L; Fegan, C D; Milligan, D W

1999-01-01

AIMS: To assess the feasibility of training nurse practitioners to perform bone marrow aspiration and trephine biopsy, and to compare the quality of these samples with those obtained by medical staff. METHODS: A retrospective audit was undertaken of nurse practitioner and medical staff performance in bone marrow procedures in a busy haematology day unit. RESULTS: Nurse practitioners fared favourably in comparison with medical staff in performing bone marrow trephine biopsies, with mean biopsy lengths of 11 mm and 10.7 mm respectively. However, only 78% of the smears obtained by the nurses were judged technically satisfactory, compared with 91% prepared by doctors. This discrepancy was thought to be due largely to the quality of slide spreading. CONCLUSIONS: With motivated staff and a structured educational and training programme it is possible for nurse practitioners to perform the techniques of bone marrow aspiration and biopsy, and obtain specimens of satisfactory quality, thus improving efficiency of the haematology day unit and increasing quality of patient care. Images PMID:10396248

Mesoporous 1D TiO_2 nanostructures obtained by the hydrothermal method

International Nuclear Information System (INIS)

Cabrera, Julieta; Vilchez, Ricardo; Alarcon, Hugo; Rodriguez, Juan; Lopez, Alcides

2014-01-01

Mesoporous one dimensional nanostructures (1D) such as nanotubes/nanorods of TiO_2 were synthesized by alkaline hydrothermal treatment of TiO_2 nanoparticles obtained by Sol Gel process (SG-TiO_2). The electronic microscopy images revealed the nanotubes formation of approximately 8 nm in diameter and more than around 400 nm long after hydrothermal treatment of 18 h and 24 h. These tube-like structures were maintained after acid treatment but after annealing at 400 °C during 2 hours these turn into rod-like structures of crystalline TiO_2 corresponding to anatase phase as revealed the diffraction patterns obtained by X-Ray Diffraction (XRD). The conversion of nanoparticles into nanotubes and afterward into rodlike shape was also confirmed by the variations in the BET surface area from 201, 269 and 97 m"2/g around, respectively. The adsorption-desorption isotherms also revealed hysteresis loop typical of mesoporous materials. These qualities are attractive to use these materials for the treatment of pollutants in water, for example. (author)

Combustion behaviour of ultra clean coal obtained by chemical demineralisation

Energy Technology Data Exchange (ETDEWEB)

F. Rubiera; A. Arenillas; B. Arias; J.J. Pis; I. Suarez-Ruiz; K.M. Steel; J.W. Patrick [Instituto Nacional del Carbon, CSIC, Oviedo (Spain)

2003-10-01

The increasing environmental concern caused by the use of fossil fuels and the concomitant need for improved combustion efficiency is leading to the development of new coal cleaning and utilisation processes. However, the benefits achieved by the removal of most mineral matter from coal either by physical or chemical methods can be annulled if poor coal combustibility characteristics are attained. In this work a high volatile bituminous coal with 6% ash content was subjected to chemical demineralisation via hydrofluoric and nitric acid leaching, the ash content of the clean coal was reduced to 0.3%. The original and treated coals were devolatilised in a drop tube furnace and the structure and morphology of the resultant chars was analysed by optical and scanning electron microscopies. The reactivity characteristics of the chars were studied by isothermal combustion tests in air at different temperatures in a thermogravimetric system. Comparison of the combustion behaviour and pollutant emissions of both coals was conducted in a drop tube furnace operating at 1000{sup o}C. The results of this work indicate that the char obtained from the chemically treated coal presents very different structure, morphology and reactivity behaviour than the char from the original coal. The changes induced by the chemical treatment increased the combustion efficiency determined in the drop tube furnace, in fact higher burnout levels were obtained for the demineralised coal.

Characterization of cubic yttria-stabilized zirconia obtained by spray pyrolysis

International Nuclear Information System (INIS)

Halmenschlager, Cibele M.; Nunes, Marilia; Vieira, Ramaugusto; Bergmann, Carlos Perez; Falcade, Tiago; Malfatti, Celia de Fraga

2009-01-01

Yttria-stabilized-zirconia (YSZ) has been the object of many studies as a SOFC electrolyte. The aim of this work is to produce, by spray pyrolysis process, thin and dense films of YSZ. A disk of steel 316L, previously heated, was used as substrate. The film was obtained with zirconium acetylacetonate (Zr(C 6 H 7 O 2 ) 4 ) and yttrium chloride (YCl 3.6 H 2 O), dissolved in a mixture of ethanol + butyl carbitol with volume ratio (1:1). ZrO 2 amorphous films were deposited in the substrate heated at many temperatures. After thermal treatment at 700 deg C the films were changed into cubic yttria-stabilized-zirconia structure. The thin films obtained were characterized by thermal analysis, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and micro-Raman spectroscopy. (author)

The structure and mechanical properties of parts elaborated by direct laser deposition 316L stainless steel powder obtained in various ways

Science.gov (United States)

Loginova, I. S.; Solonin, A. N.; Prosviryakov, A. S.; Adisa, S. B.; Khalil, A. M.; Bykovskiy, D. P.; Petrovskiy, V. N.

2017-12-01

In this work the morphology, the size and the chemical composition of the powders of steel 316L received by the two methods was studied: fusion dispersion by a gas stream and reduction of metal chlorides with the subsequent plasma atomization of the received powder particles. The powder particles received by the first method have a spherical shape (aspect ratio 1,0-1,2) with an average size of 77 μm and are characterized by the absence of internal porosity. Particles of the powder received by the second method also have a spherical shape and faultless structure, however, their chemical composition may vary in different particles. The average size of particles is 32 μm. Though the obtained powders had different properties, the experimental samples received by DLD technology demonstrated by equally high durability (Ultimate strength is 623±5 and of 623±18 MPa respectively) and plasticity (38 and 41% respectively). It is established that mechanical properties of DLD samples increase for 7-10% after treatment of the surface.

Properties of Pd nanograins in C-Pd composite films obtained by PVD method

Directory of Open Access Journals (Sweden)

Kozłowski M.

2015-09-01

Full Text Available Properties of palladium nanograins obtained by sedimentation of a soluted C-Pd film prepared by PVD method are presented. These properties were studied using SEM and TEM methods. Dissolved films were prepared by PVD method and after dissolving, they were fractionated to obtain different parts classified with palladium nanograins diameters. Several classes of diameters were determined: below 20 nm, between 20 and 100 nm and above 100 nm. The defects and triple junction were observed. Multishell carbonaceous structures were found in the big and medium size Pd nanograins.

Functional and Structural Overview of G-Protein-Coupled Receptors Comprehensively Obtained from Genome Sequences

Directory of Open Access Journals (Sweden)

Makiko Suwa

2011-04-01

Full Text Available An understanding of the functional mechanisms of G-protein-coupled receptors (GPCRs is very important for GPCR-related drug design. We have developed an integrated GPCR database (SEVENS http://sevens.cbrc.jp/ that includes 64,090 reliable GPCR genes comprehensively identified from 56 eukaryote genome sequences, and overviewed the sequences and structure spaces of the GPCRs. In vertebrates, the number of receptors for biological amines, peptides, etc. is conserved in most species, whereas the number of chemosensory receptors for odorant, pheromone, etc. significantly differs among species. The latter receptors tend to be single exon type or a few exon type and show a high ratio in the numbers of GPCRs, whereas some families, such as Class B and Class C receptors, have long lengths due to the presence of many exons. Statistical analyses of amino acid residues reveal that most of the conserved residues in Class A GPCRs are found in the cytoplasmic half regions of transmembrane (TM helices, while residues characteristic to each subfamily found on the extracellular half regions. The 69 of Protein Data Bank (PDB entries of complete or fragmentary structures could be mapped on the TM/loop regions of Class A GPCRs covering 14 subfamilies.

Computational structural mechanics for engine structures

Science.gov (United States)

Chamis, C. C.

1989-01-01

The computational structural mechanics (CSM) program at Lewis encompasses: (1) fundamental aspects for formulating and solving structural mechanics problems, and (2) development of integrated software systems to computationally simulate the performance/durability/life of engine structures. It is structured to mainly supplement, complement, and whenever possible replace, costly experimental efforts which are unavoidable during engineering research and development programs. Specific objectives include: investigate unique advantages of parallel and multiprocesses for: reformulating/solving structural mechanics and formulating/solving multidisciplinary mechanics and develop integrated structural system computational simulators for: predicting structural performances, evaluating newly developed methods, and for identifying and prioritizing improved/missing methods needed. Herein the CSM program is summarized with emphasis on the Engine Structures Computational Simulator (ESCS). Typical results obtained using ESCS are described to illustrate its versatility.

Characterization of Titanium Oxide Nanoparticles Obtained by Hydrolysis Reaction of Ethylene Glycol Solution of Alkoxide

Directory of Open Access Journals (Sweden)

Naofumi Uekawa

2012-01-01

Full Text Available Transparent and stable sols of titanium oxide nanoparticles were obtained by heating a mixture of ethylene glycol solution of titanium tetraisopropoxide (TIP and a NH3 aqueous solution at 368 K for 24 h. The concentration of NH3 aqueous solution affected the structure of the obtained titanium oxide nanoparticles. For NH3 aqueous solution concentrations higher than 0.2 mol/L, a mixture of anatase TiO2 nanoparticles and layered titanic acid nanoparticles was obtained. The obtained sol was very stable without formation of aggregated precipitates and gels. Coordination of ethylene glycol to Ti4+ ions inhibited the rapid hydrolysis reaction and aggregation of the obtained nanoparticles. The obtained titanium oxide nanoparticles had a large specific surface area: larger than 350 m2/g. The obtained titanium oxide nanoparticles showed an enhanced adsorption towards the cationic dye molecules. The selective adsorption corresponded to presence of layered titanic acid on the obtained anatase TiO2 nanoparticles.

Characterization of Titanium Oxide Nanoparticles Obtained by Hydrolysis Reaction of Ethylene Glycol Solution of Alkoxide

International Nuclear Information System (INIS)

Uekawa, N.; Endo, N.; Ishii, K.; Kojima, T.; Kakegawa, K.

2012-01-01

Transparent and stable sols of titanium oxide nanoparticles were obtained by heating a mixture of ethylene glycol solution of titanium tetraisopropoxide (TIP) and a NH 3 aqueous solution at 368 K for 24 h. The concentration of NH 3 aqueous solution affected the structure of the obtained titanium oxide nanoparticles. For NH 3 aqueous solution concentrations higher than 0.2 mol/L, a mixture of anatase TiO 2 nanoparticles and layered titanic acid nanoparticles was obtained. The obtained sol was very stable without formation of aggregated precipitates and gels. Coordination of ethylene glycol to Ti4+ ions inhibited the rapid hydrolysis reaction and aggregation of the obtained nanoparticles. The obtained titanium oxide nanoparticles had a large specific surface area: larger than 350 m2/g. The obtained titanium oxide nanoparticles showed an enhanced adsorption towards the cationic dye molecules. The selective adsorption corresponded to presence of layered titanic acid on the obtained anatase TiO 2 nanoparticles.

Sub micrometric fibrillar structures of codoped poly aniline obtained by co-oxidation using the NaCl O/ammonium peroxydisulfate system: synthesis and characterization

Energy Technology Data Exchange (ETDEWEB)

Osorio F, J. E.; Gomez Y, C.; Hernandez P, M. A.; Corea T, M. L., E-mail: josorio@ipn.mx [IPN, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, U. P. Adolfo Lopez Mateos, Av. Instituto Politecnico Nacional s/n, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico)

2013-07-01

A mixture of ammonium peroxydisulfate and sodium hypochlorite (NaCl O) (co-oxi dating system) were used to obtain poly aniline (PANi) doped with HCl and camphorsulfonic acid (CsA) (co-doping). The effect of HCl/CsA ratio added during polymerization structure, morphology and electrical conductivity of the conducting polymer was investigated. When NaCl O is used, the polymerization rate is substantially increased and the morphology changes from micrometric granular to nano metric fibrillar. CsA was used as complementary dopant but also to improve the solubility of PANi in common solvents. However, results suggest that quinone-like heterocycles containing carbonyl radicals as well as phenazine-type aromatic rings might be impeding an efficient doping in detriment of the conductivity. For the characterization X-Ray diffraction analysis, UV visible spectroscopy and scanning electron microscopy were used. (Author)

Sub micrometric fibrillar structures of codoped poly aniline obtained by co-oxidation using the NaCl O/ammonium peroxydisulfate system: synthesis and characterization

International Nuclear Information System (INIS)

Osorio F, J. E.; Gomez Y, C.; Hernandez P, M. A.; Corea T, M. L.

2013-01-01

A mixture of ammonium peroxydisulfate and sodium hypochlorite (NaCl O) (co-oxi dating system) were used to obtain poly aniline (PANi) doped with HCl and camphorsulfonic acid (CsA) (co-doping). The effect of HCl/CsA ratio added during polymerization structure, morphology and electrical conductivity of the conducting polymer was investigated. When NaCl O is used, the polymerization rate is substantially increased and the morphology changes from micrometric granular to nano metric fibrillar. CsA was used as complementary dopant but also to improve the solubility of PANi in common solvents. However, results suggest that quinone-like heterocycles containing carbonyl radicals as well as phenazine-type aromatic rings might be impeding an efficient doping in detriment of the conductivity. For the characterization X-Ray diffraction analysis, UV visible spectroscopy and scanning electron microscopy were used. (Author)

Robustness Assessment of Spatial Timber Structures

DEFF Research Database (Denmark)

Kirkegaard, Poul Henning

2012-01-01

Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures many modern buildi...... to robustness of spatial timber structures and will discuss the consequences of such robustness issues related to the future development of timber structures.......Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures many modern building...... codes consider the need for robustness of structures and provide strategies and methods to obtain robustness. Therefore a structural engineer may take necessary steps to design robust structures that are insensitive to accidental circumstances. The present paper summaries issues with respect...

Polyethyleneimine patterns obtained by laser-transfer assisted by a Dynamic Release Layer onto Themanox soft substrates for cell adhesion study

International Nuclear Information System (INIS)

Dinca, V.; Mattle, T.; Palla Papavlu, A.; Rusen, L.; Luculescu, C.; Lippert, T.; Dinescu, M.

2013-01-01

The use of LIFT (Laser Induced Forward Transfer) for localized and high spatial resolution printing of many types of functional organic and inorganic, biological or synthetic materials onto substrates is an effective method in various domains (electronics, sensors, and surface biofunctionalization). Although extensive research has been dedicated to the LIFT process in the last years, there is an increasing interest for combining the advantages of this technique with specific materials characteristics for obtaining localized structures or for creating physical guidance structures that could be used as biological scaffolds. Within this context, we aim to study a new aspect related to combining the advantages of Dynamic Release Layer assisted LIFT (DRL-LIFT) with a soft substrate (i.e. Thermanox) for obtaining surface functionalization with micro and nano “porous” polymeric structures. The structures obtained with different topographical properties were evaluated by scanning electron microscopy, atomic force microscopy, optical and fluorescence microscopy. Subsequently, the structures were used as a base for cellular behavior study platforms. Preliminary in vitro tests involving two types of cells, fibroblast and oligodendrocytes, were performed on these LIFT printed platforms.

Polyethyleneimine patterns obtained by laser-transfer assisted by a Dynamic Release Layer onto Themanox soft substrates for cell adhesion study

Energy Technology Data Exchange (ETDEWEB)

Dinca, V., E-mail: dinali@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Mattle, T. [Paul Scherrer Institute, General Energy Research Department, 5232 Villigen PSI (Switzerland); Palla Papavlu, A.; Rusen, L.; Luculescu, C. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Lippert, T. [Paul Scherrer Institute, General Energy Research Department, 5232 Villigen PSI (Switzerland); Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania)

2013-08-01

The use of LIFT (Laser Induced Forward Transfer) for localized and high spatial resolution printing of many types of functional organic and inorganic, biological or synthetic materials onto substrates is an effective method in various domains (electronics, sensors, and surface biofunctionalization). Although extensive research has been dedicated to the LIFT process in the last years, there is an increasing interest for combining the advantages of this technique with specific materials characteristics for obtaining localized structures or for creating physical guidance structures that could be used as biological scaffolds. Within this context, we aim to study a new aspect related to combining the advantages of Dynamic Release Layer assisted LIFT (DRL-LIFT) with a soft substrate (i.e. Thermanox) for obtaining surface functionalization with micro and nano “porous” polymeric structures. The structures obtained with different topographical properties were evaluated by scanning electron microscopy, atomic force microscopy, optical and fluorescence microscopy. Subsequently, the structures were used as a base for cellular behavior study platforms. Preliminary in vitro tests involving two types of cells, fibroblast and oligodendrocytes, were performed on these LIFT printed platforms.

Polyethyleneimine patterns obtained by laser-transfer assisted by a Dynamic Release Layer onto Themanox soft substrates for cell adhesion study

Science.gov (United States)

Dinca, V.; Mattle, T.; Palla Papavlu, A.; Rusen, L.; Luculescu, C.; Lippert, T.; Dinescu, M.

2013-08-01

The use of LIFT (Laser Induced Forward Transfer) for localized and high spatial resolution printing of many types of functional organic and inorganic, biological or synthetic materials onto substrates is an effective method in various domains (electronics, sensors, and surface biofunctionalization). Although extensive research has been dedicated to the LIFT process in the last years, there is an increasing interest for combining the advantages of this technique with specific materials characteristics for obtaining localized structures or for creating physical guidance structures that could be used as biological scaffolds. Within this context, we aim to study a new aspect related to combining the advantages of Dynamic Release Layer assisted LIFT (DRL-LIFT) with a soft substrate (i.e. Thermanox) for obtaining surface functionalization with micro and nano "porous" polymeric structures. The structures obtained with different topographical properties were evaluated by scanning electron microscopy, atomic force microscopy, optical and fluorescence microscopy. Subsequently, the structures were used as a base for cellular behavior study platforms. Preliminary in vitro tests involving two types of cells, fibroblast and oligodendrocytes, were performed on these LIFT printed platforms.

LEP and results obtained by DELPHI after four years of operation

International Nuclear Information System (INIS)

Blocki, J.

1993-10-01

We characterize the most important problems of modern elementary particles physics, for the solution of which the LEP (Large Electron Positron) accelerator was built. We present the characteristics of this accelerator. The structure and properties of the DELPHI detector are described with special emphasis on the contribution of Polish groups. The most important results obtained so far in the LEP accelerator are discussed. (author). 12 refs, 17 figs, 1 tab

Obtaining and Estimating Low Noise Floors in Vibration Sensors

DEFF Research Database (Denmark)

Brincker, Rune; Larsen, Jesper Abildgaard

2007-01-01

For some applications like seismic applications and measuring ambient vibrations in structures, it is essential that the noise floors of the sensors and other system components are low and known to the user. Some of the most important noise sources are reviewed and it is discussed how the sensor...... can be designed in order to obtain a low noise floor. Techniques to estimate the noise floors for sensors are reviewed and are demonstrated on a commercial commonly used sensor for vibration testing. It is illustrated how the noise floor can be calculated using the coherence between simultaneous...

Investigation of microstructure and morphology for the Ge on porous silicon/Si substrate hetero-structure obtained by molecular beam epitaxy

International Nuclear Information System (INIS)

Gouder, S.; Mahamdi, R.; Aouassa, M.; Escoubas, S.; Favre, L.; Ronda, A.; Berbezier, I.

2014-01-01

Thick porous silicon (PS) buffer layers are used as sacrificial layers to epitaxially grow planar and fully relaxed Ge membranes. The single crystal Ge layers have been deposited by molecular beam epitaxy (MBE) on PS substrate. During deposition, the pore network of PS layers has been filled with Ge. We investigate the structure and morphology of PS as fabricated and after annealing at various temperatures. We show that the PS crystalline lattice is distorted and expanded in the direction perpendicular to the substrate plane due to the presence of chemisorbed –OH. An annealing at high temperature (> 500 °C), greatly changes the PS morphology and structure. This change is marked by an increase of the pore diameter while the lattice parameter becomes tensily strained in the plane (compressed in the direction perpendicular). The morphology and structure of Ge layers are investigated by transmission electron microscopy, high resolution X-ray diffraction and atomic force microscopy as a function of the deposition temperature and deposited thickness. The results show that the surface roughness, level of relaxation and Si-Ge intermixing (Ge content) depend on the growth temperature and deposited thickness. Two sub-layers are distinguished: the layer incorporated inside the PS pores (high level of intermixing) and the layer on top of the PS surface (low level of intermixing). When deposited at temperature > 500 °C, the Ge layers are fully relaxed with a top Si 1−x Ge x layer x = 0.74 and a very flat surface. Such layer can serve as fully relaxed ultra-thin SiGe pseudo-substrate with high Ge content. The epitaxy of Ge on sacrificial soft PS pseudo-substrate in the experimental conditions described here provides an easy way to fabricate fully relaxed SiGe pseudo-substrates. Moreover, Ge thin films epitaxially deposited by MBE on PS could be used as relaxed pseudo-substrate in conventional microelectronic technology. - Highlights: • We have developed a rapid and low

Insights into the physiological function of cellular prion protein

Directory of Open Access Journals (Sweden)

Martins V.R.

2001-01-01

Full Text Available Prions have been extensively studied since they represent a new class of infectious agents in which a protein, PrPsc (prion scrapie, appears to be the sole component of the infectious particle. They are responsible for transmissible spongiform encephalopathies, which affect both humans and animals. The mechanism of disease propagation is well understood and involves the interaction of PrPsc with its cellular isoform (PrPc and subsequently abnormal structural conversion of the latter. PrPc is a glycoprotein anchored on the cell surface by a glycosylphosphatidylinositol moiety and expressed in most cell types but mainly in neurons. Prion diseases have been associated with the accumulation of the abnormally folded protein and its neurotoxic effects; however, it is not known if PrPc loss of function is an important component. New efforts are addressing this question and trying to characterize the physiological function of PrPc. At least four different mouse strains in which the PrP gene was ablated were generated and the results regarding their phenotype are controversial. Localization of PrPc on the cell membrane makes it a potential candidate for a ligand uptake, cell adhesion and recognition molecule or a membrane signaling molecule. Recent data have shown a potential role for PrPc in the metabolism of copper and moreover that this metal stimulates PrPc endocytosis. Our group has recently demonstrated that PrPc is a high affinity laminin ligand and that this interaction mediates neuronal cell adhesion and neurite extension and maintenance. Moreover, PrPc-caveolin-1 dependent coupling seems to trigger the tyrosine kinase Fyn activation. These data provide the first evidence for PrPc involvement in signal transduction.

Integrity of Helix 2-Helix 3 Domain of the PrP Protein Is Not Mandatory for Prion Replication*

Science.gov (United States)

Salamat, Khalid; Moudjou, Mohammed; Chapuis, Jérôme; Herzog, Laetitia; Jaumain, Emilie; Béringue, Vincent; Rezaei, Human; Pastore, Annalisa; Laude, Hubert; Dron, Michel

2012-01-01

The process of prion conversion is not yet well understood at the molecular level. The regions critical for the conformational change of PrP remain mostly debated and the extent of sequence change acceptable for prion conversion is poorly documented. To achieve progress on these issues, we applied a reverse genetic approach using the Rov cell system. This allowed us to test the susceptibility of a number of insertion mutants to conversion into prion in the absence of wild-type PrP molecules. We were able to propagate several prions with 8 to 16 extra amino acids, including a polyglycine stretch and His or FLAG tags, inserted in the middle of the protease-resistant fragment. These results demonstrate the possibility to increase the length of the loop between helices H2 and H3 up to 4-fold, without preventing prion replication. They also indicate that this loop probably remains unstructured in PrPSc. We also showed that bona fide prions can be produced following insertion of octapeptides in the two C-terminal turns of H2. These insertions do not interfere with the overall fold of the H2-H3 domain indicating that the highly conserved sequence of the terminal part of H2 is not critical for the conversion. Altogether these data showed that the amplitude of modifications acceptable for prion conversion in the core of the globular domain of PrP is much greater than one might have assumed. These observations should help to refine structural models of PrPSc and elucidate the conformational changes underlying prions generation. PMID:22511770

Integrity of helix 2-helix 3 domain of the PrP protein is not mandatory for prion replication.

Science.gov (United States)

Salamat, Khalid; Moudjou, Mohammed; Chapuis, Jérôme; Herzog, Laetitia; Jaumain, Emilie; Béringue, Vincent; Rezaei, Human; Pastore, Annalisa; Laude, Hubert; Dron, Michel

2012-06-01

The process of prion conversion is not yet well understood at the molecular level. The regions critical for the conformational change of PrP remain mostly debated and the extent of sequence change acceptable for prion conversion is poorly documented. To achieve progress on these issues, we applied a reverse genetic approach using the Rov cell system. This allowed us to test the susceptibility of a number of insertion mutants to conversion into prion in the absence of wild-type PrP molecules. We were able to propagate several prions with 8 to 16 extra amino acids, including a polyglycine stretch and His or FLAG tags, inserted in the middle of the protease-resistant fragment. These results demonstrate the possibility to increase the length of the loop between helices H2 and H3 up to 4-fold, without preventing prion replication. They also indicate that this loop probably remains unstructured in PrP(Sc). We also showed that bona fide prions can be produced following insertion of octapeptides in the two C-terminal turns of H2. These insertions do not interfere with the overall fold of the H2-H3 domain indicating that the highly conserved sequence of the terminal part of H2 is not critical for the conversion. Altogether these data showed that the amplitude of modifications acceptable for prion conversion in the core of the globular domain of PrP is much greater than one might have assumed. These observations should help to refine structural models of PrP(Sc) and elucidate the conformational changes underlying prions generation.

The MWCNTs-Rh Nanocomposite Obtained By The New High-Temperature Method

Directory of Open Access Journals (Sweden)

Dobrzańska-Danikiewicz A.D.

2015-06-01

Full Text Available A nanocomposite was fabricated during the research undertaken, consisting of multiwalled carbon nanotubes coated with rhodium nanoparticles by the new high-temperature method being the subject of the patent claim. High quality multiwalled carbon nanotubes (MWCNTs with the length of 100÷500 nm and the diameter of 8÷20 nm obtained in advance with Catalytic Chemical Vapour Deposition (CVD were employed in the investigations. The nanotubes manufactured under the own research contain small amounts of metallic impurities and amorphous carbon deposits. Multiwalled carbon nanotubes functionalisation in acids was applied to deposit rhodium nanoparticles onto the surface of carbon nanotubes, and then the material was placed in a solution being a precursor of rhodium nanoparticles. The material prepared was next placed in a quartz vessel and subjected to high-temperature reduction in the atmosphere of argon to deposit rhodium nanoparticles onto the surface of multiwalled carbon nanotubes. The following examinations were performed, respectively: MWCNTs fabrication, fabrication of a CNT-NPs (Carbon NanoTube-NanoParticles nanocomposite material; the characterisation of the materials produced including examination of the structure and morphology, and the assessment of rhodium nanoparticles distribution on the surface of carbon nanotubes. Micro- and spectroscopy techniques were employed to characterise the structure of the nanocomposites obtained.

Isolation and crystal structure determination of piperazine dicarbamate obtained from a direct reaction

Energy Technology Data Exchange (ETDEWEB)

Sim, Jae Ung; Jo, Eun Hee; Jhon, Young Ho; Paek, Kyung Soo; Kim, Ja Heon [Dept. of Chemistry, Soongsil University, Seoul (Korea, Republic of); Jang Se Gyu; Shim, Jae Goo; Jang, Kyung Ryong [Korea Future Technology Research Laboratory, Korea Electric Power Research Institute (KEPRI), Daejeon (Korea, Republic of)

2016-11-15

Separation of CO{sub 2} in the flue gas emitted from coal-fired power plants is the first technological step toward reducing the CO{sub 2} concentration in atmosphere, and eventually for mitigating the global climate change. We could isolate the PZ-dicarbamate, where two CO{sub 2} molecules are bonded to each secondary amine group, through CO{sub 2} absorption by PZ in methanol, and determined its crystal structure by X-ray crystallography. The PZ-dicarbamate as a salt with piperazinium allowed further analyses such as TGA and NMR measurements, which gave information on the fate of the salt. In particular, the salt can be used as a standard sample exhibiting 100% CO{sub 2} loading in a PZ molecule.

Substitutions of PrP N-terminal histidine residues modulate scrapie disease pathogenesis and incubation time in transgenic mice.

Science.gov (United States)

Eigenbrod, Sabina; Frick, Petra; Bertsch, Uwe; Mitteregger-Kretzschmar, Gerda; Mielke, Janina; Maringer, Marko; Piening, Niklas; Hepp, Alexander; Daude, Nathalie; Windl, Otto; Levin, Johannes; Giese, Armin; Sakthivelu, Vignesh; Tatzelt, Jörg; Kretzschmar, Hans; Westaway, David

2017-01-01

Prion diseases have been linked to impaired copper homeostasis and copper induced-oxidative damage to the brain. Divalent metal ions, such as Cu2+ and Zn2+, bind to cellular prion protein (PrPC) at octapeptide repeat (OR) and non-OR sites within the N-terminal half of the protein but information on the impact of such binding on conversion to the misfolded isoform often derives from studies using either OR and non-OR peptides or bacterially-expressed recombinant PrP. Here we created new transgenic mouse lines expressing PrP with disrupted copper binding sites within all four histidine-containing OR's (sites 1-4, H60G, H68G, H76G, H84G, "TetraH>G" allele) or at site 5 (composed of residues His-95 and His-110; "H95G" allele) and monitored the formation of misfolded PrP in vivo. Novel transgenic mice expressing PrP(TetraH>G) at levels comparable to wild-type (wt) controls were susceptible to mouse-adapted scrapie strain RML but showed significantly prolonged incubation times. In contrast, amino acid replacement at residue 95 accelerated disease progression in corresponding PrP(H95G) mice. Neuropathological lesions in terminally ill transgenic mice were similar to scrapie-infected wt controls, but less severe. The pattern of PrPSc deposition, however, was not synaptic as seen in wt animals, but instead dense globular plaque-like accumulations of PrPSc in TgPrP(TetraH>G) mice and diffuse PrPSc deposition in (TgPrP(H95G) mice), were observed throughout all brain sections. We conclude that OR and site 5 histidine substitutions have divergent phenotypic impacts and that cis interactions between the OR region and the site 5 region modulate pathogenic outcomes by affecting the PrP globular domain.

Interaction of human laminin receptor with Sup35, the [PSI⁺] prion-forming protein from S. cerevisiae: a yeast model for studies of LamR interactions with amyloidogenic proteins.

Directory of Open Access Journals (Sweden)

Christine Pampeno

Full Text Available The laminin receptor (LamR is a cell surface receptor for extracellular matrix laminin, whereas the same protein within the cell interacts with ribosomes, nuclear proteins and cytoskeletal fibers. LamR has been shown to be a receptor for several bacteria and viruses. Furthermore, LamR interacts with both cellular and infectious forms of the prion protein, PrP(C and PrP(Sc. Indeed, LamR is a receptor for PrP(C. Whether LamR interacts with PrP(Sc exclusively in a capacity of the PrP receptor, or LamR specifically recognizes prion determinants of PrP(Sc, is unclear. In order to explore whether LamR has a propensity to interact with prions and amyloids, we examined LamR interaction with the yeast prion-forming protein, Sup35. Sup35 is a translation termination factor with no homology or functional relationship to PrP. Plasmids expressing LamR or LamR fused with the green fluorescent protein (GFP were transformed into yeast strain variants differing by the presence or absence of the prion conformation of Sup35, respectively [PSI⁺] and [psi⁻]. Analyses by immunoprecipitation, centrifugal fractionation and fluorescent microscopy reveal interaction between LamR and Sup35 in [PSI⁺] strains. The presence of [PSI⁺] promotes LamR co-precipitation with Sup35 as well as LamR aggregation. In [PSI⁺] cells, LamR tagged with GFP or mCherry forms bright fluorescent aggregates that co-localize with visible [PSI⁺] foci. The yeast prion model will facilitate studying the interaction of LamR with amyloidogenic prions in a safe and easily manipulated system that may lead to a better understanding and treatment of amyloid diseases.

Glycoform-Selective Prion Formation in Sporadic and Familial Forms of Prion Disease

Science.gov (United States)

Xiao, Xiangzhu; Yuan, Jue; Haïk, Stéphane; Cali, Ignazio; Zhan, Yian; Moudjou, Mohammed; Li, Baiya; Laplanche, Jean-Louis; Laude, Hubert; Langeveld, Jan; Gambetti, Pierluigi; Kitamoto, Tetsuyuki; Kong, Qingzhong; Brandel, Jean-Philippe; Cobb, Brian A.; Petersen, Robert B.; Zou, Wen-Quan

2013-01-01

The four glycoforms of the cellular prion protein (PrPC) variably glycosylated at the two N-linked glycosylation sites are converted into their pathological forms (PrPSc) in most cases of sporadic prion diseases. However, a prominent molecular characteristic of PrPSc in the recently identified variably protease-sensitive prionopathy (VPSPr) is the absence of a diglycosylated form, also notable in familial Creutzfeldt-Jakob disease (fCJD), which is linked to mutations in PrP either from Val to Ile at residue 180 (fCJDV180I) or from Thr to Ala at residue 183 (fCJDT183A). Here we report that fCJDV180I, but not fCJDT183A, exhibits a proteinase K (PK)-resistant PrP (PrPres) that is markedly similar to that observed in VPSPr, which exhibits a five-step ladder-like electrophoretic profile, a molecular hallmark of VPSPr. Remarkably, the absence of the diglycosylated PrPres species in both fCJDV180I and VPSPr is likewise attributable to the absence of PrPres glycosylated at the first N-linked glycosylation site at residue 181, as in fCJDT183A. In contrast to fCJDT183A, both VPSPr and fCJDV180I exhibit glycosylation at residue 181 on di- and monoglycosylated (mono181) PrP prior to PK-treatment. Furthermore, PrPV180I with a typical glycoform profile from cultured cells generates detectable PrPres that also contains the diglycosylated PrP in addition to mono- and unglycosylated forms upon PK-treatment. Taken together, our current in vivo and in vitro studies indicate that sporadic VPSPr and familial CJDV180I share a unique glycoform-selective prion formation pathway in which the conversion of diglycosylated and mono181 PrPC to PrPSc is inhibited, probably by a dominant-negative effect, or by other co-factors. PMID:23527023

Structural, optical and electrical properties of quasi-monocrystalline silicon thin films obtained by rapid thermal annealing of porous silicon layers

International Nuclear Information System (INIS)

Hajji, M.; Khardani, M.; Khedher, N.; Rahmouni, H.; Bessais, B.; Ezzaouia, H.; Bouchriha, H.

2006-01-01

Quasi-mono-crystalline silicon (QMS) layers have a top surface like crystalline silicon with small voids in the body. Such layers are reported to have a higher absorption coefficient than crystalline silicon at the interesting range of the solar spectrum for photovoltaic application. In this work we present a study of the structural, optical and electrical properties of quasimonocrystalline silicon thin films. Quasimonocrystalline silicon thin films were obtained from porous silicon, which has been annealed at a temperature ranging from 950 to 1050 deg. C under H 2 atmosphere for different annealing durations. The porous layers were prepared by conventional electrochemical anodization using a double tank cell and a HF / Ethanol electrolyte. Porous silicon is formed on highly doped p + -type silicon substrates that enable us to prevent back contacts for the anodization. Atomic Force Microscope (AFM) was used to study the morphological quality of the prepared layers. Optical properties were extracted from transmission and reflectivity spectra. Dark I-V characteristics were used to determine the electrical conductivity of quasimonocrystalline silicon thin films. Results show an important improvement of the absorption coefficient of the material and electrical conductivity reaches a value of twenty orders higher than that of starting mesoporous silicon

Peroxiredoxin 6 promotes upregulation of the prion protein (PrP in neuronal cells of prion-infected mice

Directory of Open Access Journals (Sweden)

Wagner Wibke

2012-12-01

Full Text Available Abstract Background It has been widely established that the conversion of the cellular prion protein (PrPC into its abnormal isoform (PrPSc is responsible for the development of transmissible spongiform encephalopathies (TSEs. However, the knowledge of the detailed molecular mechanisms and direct functional consequences within the cell is rare. In this study, we aimed at the identification of deregulated proteins which might be involved in prion pathogenesis. Findings Apolipoprotein E and peroxiredoxin 6 (PRDX6 were identified as upregulated proteins in brains of scrapie-infected mice and cultured neuronal cell lines. Downregulation of PrP gene expression using specific siRNA did not result in a decrease of PRDX6 amounts. Interestingly, selective siRNA targeting PRDX6 or overexpression of PRDX6 controlled PrPC and PrPSc protein amounts in neuronal cells. Conclusions Besides its possible function as a novel marker protein in the diagnosis of TSEs, PDRX6 represents an attractive target molecule in putative pharmacological intervention strategies in the future.

Utilizing NMR and EPR spectroscopy to probe the role of copper in prion diseases

KAUST Repository

Emwas, Abdul-Hamid M.; Al-Talla, Zeyad; Guo, Xianrong; Al-Ghamdi, Suliman; Al-Masri, Harbi Tomah

2013-01-01

Copper is an essential nutrient for the normal development of the brain and nervous system, although the hallmark of several neurological diseases is a change in copper concentrations in the brain and central nervous system. Prion protein (PrP) is a copper-binding, cell-surface glycoprotein that exists in two alternatively folded conformations: a normal isoform (PrPC) and a disease-associated isoform (PrPSc). Prion diseases are a group of lethal neurodegenerative disorders that develop as a result of conformational conversion of PrPC into PrPSc. The pathogenic mechanism that triggers this conformational transformation with the subsequent development of prion diseases remains unclear. It has, however, been shown repeatedly that copper plays a significant functional role in the conformational conversion of prion proteins. In this review, we focus on current research that seeks to clarify the conformational changes associated with prion diseases and the role of copper in this mechanism, with emphasis on the latest applications of NMR and EPR spectroscopy to probe the interactions of copper with prion proteins. Copyright © 2013 John Wiley & Sons, Ltd.

Utilizing NMR and EPR spectroscopy to probe the role of copper in prion diseases

KAUST Repository

Emwas, Abdul-Hamid M.

2013-02-24

Copper is an essential nutrient for the normal development of the brain and nervous system, although the hallmark of several neurological diseases is a change in copper concentrations in the brain and central nervous system. Prion protein (PrP) is a copper-binding, cell-surface glycoprotein that exists in two alternatively folded conformations: a normal isoform (PrPC) and a disease-associated isoform (PrPSc). Prion diseases are a group of lethal neurodegenerative disorders that develop as a result of conformational conversion of PrPC into PrPSc. The pathogenic mechanism that triggers this conformational transformation with the subsequent development of prion diseases remains unclear. It has, however, been shown repeatedly that copper plays a significant functional role in the conformational conversion of prion proteins. In this review, we focus on current research that seeks to clarify the conformational changes associated with prion diseases and the role of copper in this mechanism, with emphasis on the latest applications of NMR and EPR spectroscopy to probe the interactions of copper with prion proteins. Copyright © 2013 John Wiley & Sons, Ltd.

'Ab initio' structure solution from electron diffraction data obtained by a combination of automated diffraction tomography and precession technique

International Nuclear Information System (INIS)

Mugnaioli, E.; Gorelik, T.; Kolb, U.

2009-01-01

Using a combination of our recently developed automated diffraction tomography (ADT) module with precession electron technique (PED), quasi-kinematical 3D diffraction data sets of an inorganic salt (BaSO 4 ) were collected. The lattice cell parameters and their orientation within the data sets were found automatically. The extracted intensities were used for 'ab initio' structure analysis by direct methods. The data set covered almost the complete set of possible symmetrically equivalent reflections for an orthorhombic structure. The structure solution in one step delivered all heavy (Ba, S) as well as light atoms (O). Results of the structure solution using direct methods, charge flipping and maximum entropy algorithms as well as structure refinement for three different 3D electron diffraction data sets were presented.

Preparative yield and properties of humic acids obtained by sequential alkaline extractions

Science.gov (United States)

Kholodov, V. A.; Yaroslavtseva, N. V.; Konstantinov, A. I.; Perminova, I. V.

2015-10-01

The preparative yield, composition, and structure of humic acids obtained by sequential alkaline extractions from two soils (a soddy-podzolic soil under forest and a typical chernozem in treatment with permanent black fallow of a long-term experiment since 1964) have been studied. The preparative yield of humic acids from the first extraction is 0.40 and 0.94% for the soddy-podzolic soil (Retisols) and the chernozem, respectively. The preparative yield from the second extraction is lower by several times, and the yield from the third extraction is lower by an order of magnitude. The study of the obtained preparations by elemental analysis, gel-permeation chromatography, and 13C NMR spectroscopy has shown insignificant changes in the elemental, molecular-weight, and structural-group composition of humic acids among the extractions. It has been supposed that this is related to the soil features: typical climatic factors for the formation of soil subtype in the case of soddy-podzolic soil and the land use in the long-term experiment in the case of typical chernozem. It has been concluded that that a single extraction is sufficient for the separation of humic acids and the preparation of a representative sample.

The role of the temperature in the morphology and properties of zinc oxide structures obtained by electrosynthesis in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Jaffry, U.; Mazario, E. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain); Lemus, J. [CICECO – Aveiro Institute of Materials, Chemistry Department, University of Aveiro, 3810-193 Aveiro (Portugal); Rivero, M.; Muñoz-Bonilla, A. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Física Aplicada, 28049 Madrid (Spain)

2016-09-15

Herein, ZnO micro and nanostructures were synthesized by an electrochemical method in aqueous solution employing NaCl as the electrolyte. Different parameters influencing the synthesis process, i.e. current intensity, reaction time and temperature, were investigated. From this, it was concluded that the productivity of the reaction increases with longer reaction time, whereas the use of higher current intensity augments the specific energy consumption. On the other hand, the increase in temperature seems to exert a negative effect. The characterization of the resulting materials by scanning electron microscopy, X-ray diffraction and thermogravimetric analysis demonstrated that a mixture of Zn(OH){sub 2} and ZnO crystalline structures is formed directly from the synthesis procedure. The content of Zn(OH){sub 2} phase in the sample decreases as the temperature of the synthesis increases, this fact indicates that the low productivity obtained at higher temperatures is related to the nature of the resulting material. Thermal annealing of the samples containing both phases prepared following synthesis allows the phase transformation from Zn(OH){sub 2} to pure ZnO structures. The band gap energies of the ZnO materials were determined by diffuse reflectance measurements according to the Kubelka Munk theory, revealing low values in all the cases which were highly dependent on the size of crystals within the materials. The photocatalytic properties of the pure ZnO samples post calcination were investigated by the decomposition of an organic dye under UV light irradiation. The results show the beneficial photocatalytic properties of the samples that had undergone calcination, these were superior in comparison to those prepared at room temperature which mainly consisted of Zn(OH){sub 2}. - Highlights: • ZnO micro and nanostructures were synthesized by an electrochemical method. • Increasing the applied current and synthesis temperature augments the specific energy

A code for structural analysis of fuel assemblies

International Nuclear Information System (INIS)

Hayashi, I.M.V.; Perrotta, J.A.

1988-08-01

It's presented the code ELCOM for the matrix analysis of tubular structures coupled by rigid spacers, typical of PWR's fuel elements. The code ELCOM makes a static structural analysis, where the displacements and internal forces are obtained for each tubular structure at the joints with the spacers, and also, the natural frequencies and vibrational modes of an equilavent integrated structure are obtained. The ELCOM result is compared to a PWR fuel element structural analysis obtained in published paper. (author) [pt

A saturation property of structures obtained by forcing with a compact family of random variables

Czech Academy of Sciences Publication Activity Database

Krajíček, Jan

2013-01-01

Roč. 52, 1-2 (2013), s. 19-28 ISSN 1432-0665 R&D Projects: GA AV ČR IAA100190902 Keywords : Boolean-valued structures * saturation property * non-standard model of arithmetic Subject RIV: BA - General Mathematics Impact factor: 0.324, year: 2013 http://link.springer.com/article/10.1007%2Fs00153-012-0304-9

Influence of Co{sup 2+} on the structural and magnetic properties of substituted magnetites obtained by the coprecipitation method

Energy Technology Data Exchange (ETDEWEB)

Velásquez, A. A., E-mail: avelas26@eafit.edu.edu.co [Universidad EAFIT, Grupo de Electromagnetismo Aplicado (Colombia); Urquijo, J. P. [Universidad de Antioquia, Grupo de Estado Sólido, Instituto de Física (Colombia)

2015-06-15

In this paper we report the effect of divalent cobalt on the structural and magnetic properties of substituted magnetites, Fe {sub 3−x}Co {sub x}O{sub 4}, with γ=Co {sup 2+}/Fe = 0, 5, 10, 15, 20 and 30 % wt, synthesized by the coprecipitation method. The samples were characterized by Atomic Absorption Spectroscopy, X-ray Diffraction, room temperature Mössbauer Spectroscopy and Vibrating Sample Magnetometry. The effect of Co {sup 2+} was found to depend strongly of the concentration employed in the synthesis process. For γ≤15 % the Co {sup 2+} promotes the formation of particles more crystalline and with higher saturation magnetization, remanence and coercivity than those obtained in absence of this cation. A sequential increasing of the lattice parameter is observed, as well as a reduction in the hyperfine magnetic field of the Fe {sup 2.5+}sub spectrum, while the hyperfine magnetic field of the Fe {sup 3+}sub spectrum keeps almost constant. For γ=20 % and 30 % the crystallinity of the samples decreases, particle size distribution effects are evidenced and the saturation magnetization decreases drastically. The results suggest that for low Co {sup 2+} contents the substitution of Fe {sup 3+}by Co {sup 2+} at octahedral sites of the inverse spinel system is the dominant effect, while for the highest concentrations used the substitution of Fe {sup 2+} by Co {sup 2+} and the increasing of the particle size distribution are the dominant effects.

3D images of paper obtained by phase-contrast X-ray microtomography: image quality and binarisation

International Nuclear Information System (INIS)

Antoine, Christine; Nygaard, Per; Gregersen, O.W.; Holmstad, Rune; Weitkamp, Timm; Rau, Christoph

2002-01-01

A series of paper samples was investigated using high-resolution phase-contrast microtomography at the beamline ID 22 of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. It was shown that X-ray microtomography is a non-destructive method suitable for high resolution depicting real 3D-paper structures. The method detects highly localised changes in the refractive index of the sample, such as fibre-pore interfaces. The resulting tomograms represented an outlined image of the fibre structure with an image resolution of 1 μm. Analyses were performed in dry state, but in addition some were done in wet state. The raw data obtained were transformed into 3D images. The reconstructed slices were in general of rather good quality, even if both noise and ring-like artifacts were observed. These required special filtering efforts before a segmented binary volume could be obtained for further use of the data. This approach was made up of semi-automatic routines to convert the structure into a binary format. The resulting binary volumes can be used for further characterisation of the 3D-paper structure

Study for obtaining a suppressor device of transients using the Al/SRO/Si structure; Estudio para la obtencion de un dispositivo supresor de transitorios utilizando la estructura Al/SRO/Si

Energy Technology Data Exchange (ETDEWEB)

Marin Ramos, Heriberto

1999-06-01

The circuits and electronic equipment use protective devices against voltage transients. In this work the Aluminium/Oxide structure rich in Silicon/Silicon is presented as another option in the field of transient suppressors devices. Some devices used in the suppression of voltage transients are: zinc oxide varistors, of silicon carbide varistors, selenium cells, and Zener diodes. The Al/SRO/Si structure presents conductive properties due to the presence of excess Silicon in the SRO film. Varying the reacting gases ratio (Ro=N{sub 2}O/SiH{sub 4}) during the growth of the film of Oxide Rich in Silicon (SRO), the conductivity of the material can be varied. The SRO turns out to be of great importance for the suppressor device of transients device that is pretended to be obtained in the present work due to its non-ohmic behavior. The Al/SRO/Si device behaves of several ways depending on the characteristics of the SRO and the silicon substrate. It has been found that one of these behaviors is as a of voltage transients suppressor. Verifying its behavior as transient suppressor, the effects of the film thickness, the area and the excess of silicon of the device were studied, for this purpose the characteristic I-V was obtained, and the obtention of some parameters in DC. In the present work the SRO was obtained by means of LPCVD (Low Pressure Chemical Vapor Deposition), initially a C-V characterization was made to obtain an indicative parameter of excess silicon, such as: permittivity of the SRO film. Also, the refraction index was obtained, which is an indicative parameter of the presence of excess Silicon. Once having the certainty of the presence of excess silicon it was proceed to obtain the I-V characteristic of the Al/SRO/Si structure as a device. The behavior of the Al/SRO/Si structure was analyzed with different parameters, such as: Ro, thickness of the SOR, areas. [Spanish] Los circuitos y equipos electronicos utilizan dispositivos de proteccion contra

Structural and photocatalytic properties of iron- and europium-doped TiO2 nanoparticles obtained under hydrothermal conditions

International Nuclear Information System (INIS)

Diamandescu, L.; Vasiliu, F.; Tarabasanu-Mihaila, D.; Feder, M.; Vlaicu, A.M.; Teodorescu, C.M.; Macovei, D.; Enculescu, I.; Parvulescu, V.; Vasile, E.

2008-01-01

Iron- and europium-doped (≤1 at.%) TiO 2 nanoparticles powders have been synthesized by a hydrothermal route at 200 deg. C, starting with TiCl 4 , FeCl 3 .6H 2 O and EuCl 3 .6H 2 O. The structure, morphology and optical peculiarities were investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS), Moessbauer spectroscopy and UV-vis measurements. The photocatalytic performance was analysed in the photodegradation reaction of phenol. Rietveld refinements of XRD patterns reveal that the as-prepared samples consist in iron- and europium-doped TiO 2 in the tetragonal anatase structural shape, with particle size as low as 15 nm. By means of Moessbauer spectroscopy on both 57 Fe and 151 Eu isotopes as well as by EXAFS analyses, the presence of Fe 3+ and/or Eu 3+ ions in the nanosized powders has been evidenced. It was found that iron and europium ions can substitute for titanium in the anatase structure. From the UV-vis reflection spectra, by using the transformed Kubelka-Munk functions, the band gap energy (E g ) of the hydrothermal samples has been determined in comparison with that of Degussa P-25 photocatalyst. A decrease of E g from 2.9 eV found for Degussa photocatalyst to 2.8 eV for the titania doped with 1 at.% Fe has been evidenced, indicating a valuable absorption shift (∼20 nm) towards visible light region. However, the best photocatalytic activity in the photodegradation reaction of phenol was evidenced for the hydrothermal sample, TiO 2 : 1 at.% Fe, 0.5 at.% Eu, in both UV and visible light regions. The photocatalytic activities of iron-doped and iron-europium-codoped samples are high and practically the same only in visible light. The photocatalytic properties in correlation with the structural and optical peculiarities of the hydrothermal samples are discussed

Chromium(III) Complex Obtained from Dipicolinic Acid: Synthesis, Characterization, X-Ray Crystal Structure and Electrochemical Studies

Energy Technology Data Exchange (ETDEWEB)

Ghasemi, Khaled; Rezvani, Ali Reza; Ghasemi, Fatemeh [Univ. of Sistan and Baluchestan, Zahedan (Iran, Islamic Republic of); Razak, Ibrahim Abdul; Rosli, Mohd Mustaqim [Universiti Sains Malaysia, Penang (Malaysia)

2013-10-15

The synthesis, X-ray crystallography, spectroscopic (IR, UV-vis), and electrochemical properties of the title compound, [H{sub 3}O][Cr(dipic){sub 2}] [H{sub 3}O{sup +}.Cl{sup -}] (1), (H{sub 2}dipic = 2,6-pyridinedicarboxylic acid), are reported. This complex crystallizes in the monoclinic space group Cc with a = 14.9006(10) A, b = 12.2114(8) A, c = 8.6337(6) A, α = 90.00 .deg., β = 92.7460(10) .deg., γ = 90.00 .deg., and V = 1569.16(18) A3 with Z = 4. The hydrogen bonding and noncovalent interactions play roles in the stabilization of the structure. In order to gain a better understanding of the most important geometrical parameters in the structure of the complex, atoms in molecules (AIM) method at B3LYP/6-31G level of theory has been employed.

Chelate forms of biometalls. Theoretical aspects of obtaining and characteristics

Directory of Open Access Journals (Sweden)

A. Kapustyan

2017-04-01

Full Text Available The problem of microelements bioavailability is highlighted and the correct ways of its solution are substantiated as a result of generalization of theoretical aspects of obtaining of the biometals chelate forms. The characteristics of the main biogenic elements, their physiological significance, electrochemical properties are presented. The main examples of the participation of biometals in various biological processes are given. The properties and the structure peculiarities of biometals coordination complexes are considered in detail. It is shown that in obtaining of biometals chelate forms, there is the mutual selectivity and the affinity of biometals and ligands. The main factors of obtaining a hard metal complex are given. Potential bioligands for obtaining bioavailable forms of microelements are detailed. Among them there are amino acids, peptides, proteins, nucleic acids, carbohydrates. The possible character of complexation depending on the nature of the bioligand is indicated. Practical examples of preparation of biometals mixed ligand complexes are given. The expediency of using metabolic products and processing of lactic acid bacteria as promising components of mixed ligand chelate complexes is substantiated. These substances contain in their composition a mass of potential donor atoms that are capable to form covalent and coordination bonds with biomethalles, and also possess high biological and immunotropic activities. The use of this system in the biocoordination compounds of the "metals of life" can provide a synergistic effect of the components, significantly to expand the range of their physiological activity and to increase the degree of assimilation by the body.

Coloration of metallic and/or ceramic surfaces obtained by atomic layer deposited nano-coatings

Energy Technology Data Exchange (ETDEWEB)

Guzman, L., E-mail: luisg47@gmail.com [Fondazione Bruno Kessler (FBK), Centro Materiali e Microsistemi, Functional Materials & Photonic Structures Unit, via Sommarive 18, 38123 Trento (Italy); Vettoruzzo, F. [Ronda High Tech, via Vegri 83, 36010 Zane’, Vicenza (Italy); Laidani, N. [Fondazione Bruno Kessler (FBK), Centro Materiali e Microsistemi, Functional Materials & Photonic Structures Unit, via Sommarive 18, 38123 Trento (Italy)

2016-02-29

By depositing single layer coatings by means of physical vapor techniques, tailoring of their coloration is generally complex because a given color can be obtained only by very high composition control. Physical vapor deposition (PVD) processes are expensive and cannot be easily used for obtaining conformal coating on three-dimensional objects. Moreover PVD coatings exhibit intrinsic defects (columnar structures, pores) that affect their functional properties and applications such as barrier layers. Atomic layer deposition (ALD) technology delivers conformal coatings on different materials with very low defectiveness. A straightforward coloration can be obtained by a combination of two types of layers with different refraction index, deposited to high thickness precision. Computer simulation studies were performed to design the thickness and architecture of multilayer structures, to a total thickness of approximately 100 nm, suitable to modify the typical coloration of some materials, without altering their other physical and chemical properties. The most promising nano-layered structures were then deposited by ALD and tested with regard to their optical properties. Their total thicknesses were specified in such a way to be technically feasible and compatible with future industrial production. The materials employed in this study to build the optical coatings, are two oxides (Al{sub 2}O{sub 3}, TiO{sub 2}) deposited at 120 °C and two nitrides (AlN, TiN), which need a deposition temperature of 400 °C. The possibility of using such modern deposition technology for esthetic and decorative purposes, while maintaining the functional properties, opens perspectives of industrial applications. - Highlights: • Computer simulation is done to design multilayers made of Al{sub 2}O{sub 3}, TiO{sub 2}, AlN, and TiN. • Total thickness (< 120 nm) is specified to be compatible with industrial production. • The most promising nano-layered structures are then produced and

Coloration of metallic and/or ceramic surfaces obtained by atomic layer deposited nano-coatings

International Nuclear Information System (INIS)

Guzman, L.; Vettoruzzo, F.; Laidani, N.

2016-01-01

By depositing single layer coatings by means of physical vapor techniques, tailoring of their coloration is generally complex because a given color can be obtained only by very high composition control. Physical vapor deposition (PVD) processes are expensive and cannot be easily used for obtaining conformal coating on three-dimensional objects. Moreover PVD coatings exhibit intrinsic defects (columnar structures, pores) that affect their functional properties and applications such as barrier layers. Atomic layer deposition (ALD) technology delivers conformal coatings on different materials with very low defectiveness. A straightforward coloration can be obtained by a combination of two types of layers with different refraction index, deposited to high thickness precision. Computer simulation studies were performed to design the thickness and architecture of multilayer structures, to a total thickness of approximately 100 nm, suitable to modify the typical coloration of some materials, without altering their other physical and chemical properties. The most promising nano-layered structures were then deposited by ALD and tested with regard to their optical properties. Their total thicknesses were specified in such a way to be technically feasible and compatible with future industrial production. The materials employed in this study to build the optical coatings, are two oxides (Al_2O_3, TiO_2) deposited at 120 °C and two nitrides (AlN, TiN), which need a deposition temperature of 400 °C. The possibility of using such modern deposition technology for esthetic and decorative purposes, while maintaining the functional properties, opens perspectives of industrial applications. - Highlights: • Computer simulation is done to design multilayers made of Al_2O_3, TiO_2, AlN, and TiN. • Total thickness (< 120 nm) is specified to be compatible with industrial production. • The most promising nano-layered structures are then produced and optically tested. • An

ANTIFUNGAL ACTIVITY OF SILVER NANOPARTICLES OBTAINED BY GREEN SYNTHESIS

Directory of Open Access Journals (Sweden)

Eduardo José J. MALLMANN

2015-04-01

Full Text Available Silver nanoparticles (AgNPs are metal structures at the nanoscale. AgNPs have exhibited antimicrobial activities against fungi and bacteria; however synthesis of AgNPs can generate toxic waste during the reaction process. Accordingly, new routes using non-toxic compounds have been researched. The proposal of the present study was to synthesize AgNPs using ribose as a reducing agent and sodium dodecyl sulfate (SDS as a stabilizer. The antifungal activity of these particles against C. albicans and C. tropicalis was also evaluated. Stable nanoparticles 12.5 ± 4.9 nm (mean ± SD in size were obtained, which showed high activity against Candida spp. and could represent an alternative for fungal infection treatment.

A computer program for structural analysis of fuel elements

International Nuclear Information System (INIS)

Hayashi, I.M.V.; Perrotta, J.A.

1988-01-01

It's presented the code ELCOM for the matrix analysis of tubular structures coupled by rigid spacers, typical of PWR's fuel elements. The code ELCOM makes a static structural analysis, where the displacements and internal forces are obtained for each structure at the joints with the spacers, and also, the natural frequencies and vibrational modes of an equivalent integrated structure are obtained. The ELCOM result is compared to a PWR fuel element structural analysis obtained in published paper. (author) [pt

SiC-Based Composite Materials Obtained by Siliconizing Carbon Matrices

Science.gov (United States)

Shikunov, S. L.; Kurlov, V. N.

2017-12-01

We have developed a method for fabrication of parts of complicated configuration from composite materials based on SiC ceramics, which employs the interaction of silicon melt with the carbon matrix having a certain composition and porosity. For elevating the operating temperatures of ceramic components, we have developed a method for depositing protective silicon-carbide coatings that is based on the interaction of the silicon melt and vapor with carbon obtained during thermal splitting of hydrocarbon molecules. The new structural ceramics are characterized by higher operating temperatures; chemical stability; mechanical strength; thermal shock, wear and radiation resistance; and parameters stability.

β-sheet-like formation during the mechanical unfolding of prion protein

Science.gov (United States)

Tao, Weiwei; Yoon, Gwonchan; Cao, Penghui; Eom, Kilho; Park, Harold S.

2015-09-01

Single molecule experiments and simulations have been widely used to characterize the unfolding and folding pathways of different proteins. However, with few exceptions, these tools have not been applied to study prion protein, PrPC, whose misfolded form PrPSc can induce a group of fatal neurodegenerative diseases. Here, we apply novel atomistic modeling based on potential energy surface exploration to study the constant force unfolding of human PrP at time scales inaccessible with standard molecular dynamics. We demonstrate for forces around 100 pN, prion forms a stable, three-stranded β-sheet-like intermediate configuration containing residues 155-214 with a lifetime exceeding hundreds of nanoseconds. A mutant without the disulfide bridge shows lower stability during the unfolding process but still forms the three-stranded structure. The simulations thus not only show the atomistic details of the mechanically induced structural conversion from the native α-helical structure to the β-rich-like form but also lend support to the structural theory that there is a core of the recombinant PrP amyloid, a misfolded form reported to induce transmissible disease, mapping to C-terminal residues ≈160-220.

Obtaining of potassium dicyan-argentate

International Nuclear Information System (INIS)

Sattarova, M.A.; Solojenkin, P.M.

1997-01-01

This work is devoted to obtaining of potassium dicyan-argentate. By means of exchange reaction between silver nitrate and potassium cyanide the potassium dicyan-argentate was synthesized. The analysis of obtained samples was carried out by means of titration and potentiometry.

Water based suspensions of iron oxide obtained by laser target evaporation for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Novoselova, I.P. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Immanuel Kant Baltic Federal University, Science and Technology Park “Fabrica”, Gaidara St. 6, 236022 Kaliningrad (Russian Federation); Safronov, A.P. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Institute of Electrophysics UD RAS, Amundsena St. 106, 620016 Yekaterinburg (Russian Federation); Samatov, O.M. [Institute of Electrophysics UD RAS, Amundsena St. 106, 620016 Yekaterinburg (Russian Federation); Beketov, I.V.; Medvedev, A.I. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Institute of Electrophysics UD RAS, Amundsena St. 106, 620016 Yekaterinburg (Russian Federation); Kurlyandskaya, G.V. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Lenin Ave. 51, 620083 Yekaterinburg (Russian Federation); Universidad del País Vasco, UPV/EHU, Dpto. de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain)

2016-10-01

In this work spherical magnetic nanoparticles (MNPs) of iron oxide were obtained by laser target evaporation technique (LTE). Water based suspensions were prepared on the basis of obtained MNPs and their properties were also studied including inductive heat capacity. Their structure and properties were studied by a number of techniques including magnetometry and heat capacity measurements. Magnetic induction heating experiment show the specific loss power (SLP) value in the narrow range from 1.30 to 1.45 W/g for all samples under consideration when using alternating magnetic field of 1.7 kA/m and frequency of 210 kHz. These parameters insure that LTE MNPs are interesting materials promising for magnetic fluid hyperthermia. - Highlights: • Spheric oxide nanoparticles obtained by productive laser target evaporation method. • Experiment shows the specific loss power value in the narrow range for all samples. • Obtained results insure these objects as interesting material for hyperthermia.

Water based suspensions of iron oxide obtained by laser target evaporation for biomedical applications

International Nuclear Information System (INIS)

Novoselova, I.P.; Safronov, A.P.; Samatov, O.M.; Beketov, I.V.; Medvedev, A.I.; Kurlyandskaya, G.V.

2016-01-01

In this work spherical magnetic nanoparticles (MNPs) of iron oxide were obtained by laser target evaporation technique (LTE). Water based suspensions were prepared on the basis of obtained MNPs and their properties were also studied including inductive heat capacity. Their structure and properties were studied by a number of techniques including magnetometry and heat capacity measurements. Magnetic induction heating experiment show the specific loss power (SLP) value in the narrow range from 1.30 to 1.45 W/g for all samples under consideration when using alternating magnetic field of 1.7 kA/m and frequency of 210 kHz. These parameters insure that LTE MNPs are interesting materials promising for magnetic fluid hyperthermia. - Highlights: • Spheric oxide nanoparticles obtained by productive laser target evaporation method. • Experiment shows the specific loss power value in the narrow range for all samples. • Obtained results insure these objects as interesting material for hyperthermia.

Structure of Sn1−xGex random alloys as obtained from the coherent potential approximation

KAUST Repository

Pulikkotil, J. J.; Chroneos, A.; Schwingenschlö gl, Udo

2011-01-01

The structure of the Sn1−xGex random alloys is studied using density functional theory and the coherent potential approximation. We report on the deviation of the Sn1−xGex alloys from Vegard’s law, addressing their full compositional range

Coating multilayer material with improved tribological properties obtained by magnetron sputtering

Science.gov (United States)

Mateescu, A. O.; Mateescu, G.; Balasoiu, M.; Pompilian, G. O.; Lungu, M.

2017-02-01

This work is based on the Patent no. RO 128094 B1, granted by the Romanian State Office for Inventions and Trademarks. The goal of the work is to obtain for investigations tribological coatings with multilayer structure with improved tribological properties, deposited by magnetron sputtering process from three materials (sputtering targets). Starting from compound chemical materials (TiC, TiB2 and WC), as sputtering targets, by deposition in argon atmosphere on polished stainless steel, we have obtained, based on the claims of the above patent, thin films of multilayer design with promising results regarding their hardness, elastic modulus, adherence, coefficient of friction and wear resistance. The sputtering process took place in a special sequence in order to ensure better tribological properties to the coating, comparing to those of the individual component materials. The tribological properties, such as the coefficient of friction, are evaluated using the tribometer test.

Synthesis and characterization of nanoparticles of nickel obtained by laser ablation

International Nuclear Information System (INIS)

Aviles, R.; Escobar A, L.; Camps, E.; Santiago, P.; Ascencio, J.A.; Von, H.

2002-01-01

The result of the formation of nickel nanoparticles by the laser ablation technique with a size less or equal to 1.3 nm is reported, also the formation of agglomerates of tens of nanometers is shown. Under the experimental conditions used a high particle density (around 10 5 particles/μm 2 ) is obtained. The stability of the particles in function of its atom quantity, for less or equal sizes to 2 nm is studied, finding that the most stable structure is the icosahedron. (Author)

Structural, magnetic, and electronic properties of iron selenide Fe{sub 6-7}Se{sub 8} nanoparticles obtained by thermal decomposition in high-temperature organic solvents

Energy Technology Data Exchange (ETDEWEB)

Lyubutin, I. S., E-mail: lyubutinig@mail.ru, E-mail: crlin@mail.npue.edu.tw; Funtov, K. O.; Dmitrieva, T. V.; Starchikov, S. S. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Moscow 119333 (Russian Federation); Lin, Chun-Rong, E-mail: lyubutinig@mail.ru, E-mail: crlin@mail.npue.edu.tw [Department of Applied Physics, National Pingtung University of Education, Pingtung 90003, Taiwan (China); Siao, Yu-Jhan [Department of Mechanical Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan (China); Chen, Mei-Li [Department of Electro-optical Engineering, Southern Taiwan University of Science and Technology, Tainan 71005, Taiwan (China)

2014-07-28

Iron selenide nanoparticles with the NiAs-like crystal structure were synthesized by thermal decomposition of iron chloride and selenium powder in a high-temperature organic solvent. Depending on the time of the compound processing at 340 °C, the nanocrystals with monoclinic (M)-Fe{sub 3}Se{sub 4} or hexagonal (H)-Fe{sub 7}Se{sub 8} structures as well as a mixture of these two phases can be obtained. The magnetic behavior of the monoclinic and hexagonal phases is very different. The applied-field and temperature dependences of magnetization reveal a complicated transformation between ferrimagnetic (FRM) and antiferromagnetic (AFM) structures, which can be related to the spin rotation process connected with the redistribution of cation vacancies. From XRD and Mössbauer data, the 3c type superstructure of vacancy ordering was found in the hexagonal Fe{sub 7}Se{sub 8}. Redistribution of vacancies in Fe{sub 7}Se{sub 8} from random to ordered leads to the transformation of the magnetic structure from FRM to AFM. The Mössbauer data indicate that vacancies in the monoclinic Fe{sub 3}Se{sub 4} prefer to appear near the Fe{sup 3+} ions and stimulate the magnetic transition with the rotation of the Fe{sup 3+} magnetic moments. Unusually high coercive force H{sub c} was found in both (H) and (M) nanocrystals with the highest (“giant”) value of about 25 kOe in monoclinic Fe{sub 3}Se{sub 4}. This is explained by the strong surface magnetic anisotropy which is essentially larger than the core anisotropy. Such a large coercivity is rare for materials without rare earth or noble metal elements, and the Fe{sub 3}Se{sub 4}-based compounds can be the low-cost, nontoxic alternative materials for advanced magnets. In addition, an unusual effect of “switching” of magnetization in a field of 10 kOe was found in the Fe{sub 3}Se{sub 4} nanoparticles below 280 K, which can be important for applications.

On the energy distribution profile of interface states obtained by taking into account of series resistance in Al/TiO2/p-Si (MIS) structures

International Nuclear Information System (INIS)

Pakma, O.; Serin, N.; Serin, T.; Altindal, S.

2011-01-01

The energy distribution profile of the interface states (N ss ) of Al/TiO 2 /p-Si (MIS) structures prepared using the sol-gel method was obtained from the forward bias current-voltage (I-V) characteristics by taking into account both the bias dependence of the effective barrier height (φ e ) and series resistance (R s ) at room temperature. The main electrical parameters of the MIS structure such as ideality factor (n), zero-bias barrier height (φ b0 ) and average series resistance values were found to be 1.69, 0.519 eV and 659 Ω, respectively. This high value of n was attributed to the presence of an interfacial insulator layer at the Al/p-Si interface and the density of interface states (N ss ) localized at the Si/TiO 2 interface. The values of N ss localized at the Si/TiO 2 interface were found with and without the R s at 0.25-E v in the range between 8.4x10 13 and 4.9x10 13 eV -1 cm -2 . In addition, the frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the structures have been investigated by taking into account the effect of N ss and R s at room temperature. It can be found out that the measured C and G/ω are strongly dependent on bias voltage and frequency. -- Research highlights: →We successfully fabricated Al/TiO 2 /p-Si device with interlayer by a sol-gel method. The facts: (i) that the technology of the fabrication of a Al/TiO 2 /p-Si MIS structure much simpler and economical than that for the Si p-n junction and (b) the main advantages of TiO 2 films are low densities of the surface states when compared to SiO 2 .

Structural analysis of rebaudioside A derivatives obtained by Lactobacillus reuteri 180 glucansucrase-catalyzed trans-α-glucosylation

NARCIS (Netherlands)

Gerwig, Gerrit J; Te Poele, Evelien M; Dijkhuizen, Lubbert; Kamerling, Johannis P

2017-01-01

The wild-type Gtf180-ΔN glucansucrase enzyme from Lactobacillus reuteri 180 was found to catalyze the α-glucosylation of the steviol glycoside rebaudioside A, using sucrose as glucosyl donor in a transglucosylation process. Structural analysis of the formed products by MALDI-TOF mass spectrometry,

Structure of the Suasselkä postglacial fault in northern Finland obtained by analysis of local events and ambient seismic noise

Science.gov (United States)

Afonin, Nikita; Kozlovskaya, Elena; Kukkonen, Ilmo; Dafne/Finland Working Group

2017-04-01

Understanding the inner structure of seismogenic faults and their ability to reactivate is particularly important in investigating the continental intraplate seismicity regime. In our study we address this problem using analysis of local seismic events and ambient seismic noise recorded by the temporary DAFNE array in the northern Fennoscandian Shield. The main purpose of the DAFNE/FINLAND passive seismic array experiment was to characterize the present-day seismicity of the Suasselkä postglacial fault (SPGF), which was proposed as one potential target for the DAFNE (Drilling Active Faults in Northern Europe) project. The DAFNE/FINLAND array comprised an area of about 20 to 100 km and consisted of eight short-period and four broadband three-component autonomous seismic stations installed in the close vicinity of the fault area. The array recorded continuous seismic data during September 2011-May 2013. Recordings of the array have being analysed in order to identify and locate natural earthquakes from the fault area and to discriminate them from the blasts in the Kittilä gold mine. As a result, we found a number of natural seismic events originating from the fault area, which proves that the fault is still seismically active. In order to study the inner structure of the SPGF we use cross-correlation of ambient seismic noise recorded by the array. Analysis of azimuthal distribution of noise sources demonstrated that during the time interval under consideration the distribution of noise sources is close to the uniform one. The continuous data were processed in several steps including single-station data analysis, instrument response removal and time-domain stacking. The data were used to estimate empirical Green's functions between pairs of stations in the frequency band of 0.1-1 Hz and to calculate corresponding surface wave dispersion curves. The S-wave velocity models were obtained as a result of dispersion curve inversion. The results suggest that the area of

Kosmotropic anions promote conversion of recombinant prion protein into a PrPSc-like misfolded form.

Directory of Open Access Journals (Sweden)

Rodrigo Diaz-Espinoza

Full Text Available Prions are self-propagating proteins involved in transmissible spongiform encephalopaties in mammals. An aberrant conformation with amyloid-like features of a cell surface protein, termed prion protein (PrP, is thought to be the essential component of the infectious particle, though accessory co-factor molecules such as lipids and nucleotides may be involved. The cellular co-factors and environmental conditions implicated in PrP misfolding are not completely understood. To address this issue, several studies have been done inducing misfolding of recombinant PrP (recPrP into classical amyloid structures using partially denaturing conditions. In this work, we report that misfolding of recPrP into PrP(Sc-like aggregates can be induced by simply incubating the protein in the presence of kosmotropic salts at concentrations that are known to retain or increase the stability of the protein. We used a simple experimental reaction (protein, buffer and salts submitted to agitation/incubation cycles at physiological temperature and pH. The formation of protease resistant-recPrP was time and salt-concentration dependent and required the presence of kosmotropic anions such as F(- or SO(4(-2. The molecular weights of the protease resistant recPrP fragments are reminiscent of those found in degradation assays of bona fide PrP(Sc. The aggregates also exhibited PrP(Sc-like ultrastructural features including rod-shape morphology under electron microscope, high beta-sheet content and thioflavin-T positive signal. The formation of recPrP aggregates with PrP(Sc biochemical features under conditions closer to physiological in the absence of organic co-factor molecules provides a simple setup that may prove helpful to understand the molecular mechanism of PrP misfolding.

Synthetic prions and other human neurodegenerative proteinopathies.

Science.gov (United States)

Le, Nhat Tran Thanh; Narkiewicz, Joanna; Aulić, Suzana; Salzano, Giulia; Tran, Hoa Thanh; Scaini, Denis; Moda, Fabio; Giachin, Gabriele; Legname, Giuseppe

2015-09-02

Transmissible spongiform encephalopathies (TSE) are a heterogeneous group of neurodegenerative disorders. The common feature of these diseases is the pathological conversion of the normal cellular prion protein (PrP(C)) into a β-structure-rich conformer-termed PrP(Sc). The latter can induce a self-perpetuating process leading to amplification and spreading of pathological protein assemblies. Much evidence suggests that PrP(Sc) itself is able to recruit and misfold PrP(C) into the pathological conformation. Recent data have shown that recombinant PrP(C) can be misfolded in vitro and the resulting synthetic conformers are able to induce the conversion of PrP(C) into PrP(Sc)in vivo. In this review we describe the state-of-the-art of the body of literature in this field. In addition, we describe a cell-based assay to test synthetic prions in cells, providing further evidence that synthetic amyloids are able to template conversion of PrP into prion inclusions. Studying prions might help to understand the pathological mechanisms governing other neurodegenerative diseases. Aggregation and deposition of misfolded proteins is a common feature of several neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and other disorders. Although the proteins implicated in each of these diseases differ, they share a common prion mechanism. Recombinant proteins are able to aggregate in vitro into β-rich amyloid fibrils, sharing some features of the aggregates found in the brain. Several studies have reported that intracerebral inoculation of synthetic aggregates lead to unique pathology, which spread progressively to distal brain regions and reduced survival time in animals. Here, we review the prion-like features of different proteins involved in neurodegenerative disorders, such as α-synuclein, superoxide dismutase-1, amyloid-β and tau. Copyright © 2014 Elsevier B.V. All rights reserved.

Disruption of the 37-kDa/67-kDa laminin receptor gene in bovine ...

African Journals Online (AJOL)

... gene encoding for the prion binding site in bovine fetal fibroblasts. The heterozygous BFF are ready to be used in producing homozygous cattle, which will be applied to study the interaction between prion and the 37-kDa/67-kDa LRP/LR. Key words: Prion, PrPC, PrPSc, 37-kDa/67-kDa laminin receptor, gene targeting.

The spatial structure of magnetospheric plasma disturbance estimated by using magnetic data obtained by SWARM satellites.

Science.gov (United States)

Yokoyama, Y.; Iyemori, T.; Aoyama, T.

2017-12-01

Field-aligned currents with various spatial scales flow into and out from high-latitude ionosphere. The magnetic fluctuations observed by LEO satellites along their orbits having period longer than a few seconds can be regarded as the manifestations of spatial structure of field aligned currents.This has been confirmed by using the initial orbital characteristics of 3 SWARM-satellites. From spectral analysis, we evaluated the spectral indices of these magnetic fluctuations and investigated their dependence on regions, such as magnetic latitude and MLT and so on. We found that the spectral indices take quite different values between the regions lower than the equatorward boundary of the auroral oval (around 63 degrees' in magnetic latitude) and the regions higher than that. On the other hands, we could not find the clear MLT dependence. In general, the FACs are believed to be generated in the magnetiospheric plasma sheet and boundary layer, and they flow along the field lines conserving their currents.The theory of FAC generation [e.g., Hasegawa and Sato ,1978] indicates that the FACs are strongly connected with magnetospheric plasma disturbances. Although the spectral indices above are these of spatial structures of the FACs over the ionosphere, by using the theoretical equation of FAC generation, we evaluate the spectral indices of magnetospheric plasma disturbance in FAC's generation regions. Furthermore, by projecting the area of fluctuations on the equatorial plane of magnetosphere (i.e. plasma sheet), we can estimate the spatial structure of magnetospheric plasma disturbance. In this presentation, we focus on the characteristics of disturbance in midnight region and discuss the relations to the substorm.

Holographic analysis of diffraction structure factors

International Nuclear Information System (INIS)

Marchesini, S.; Bucher, J.J.; Shuh, D.K.; Fabris, L.; Press, M.J.; West, M.W.; Hussain, Z.; Mannella, N.; Fadley, C.S.; Van Hove, M.A.; Stolte, W.C.

2002-01-01

We combine the theory of inside-source/inside-detector x-ray fluorescence holography and Kossel lines/ x ray standing waves in kinematic approximation to directly obtain the phases of the diffraction structure factors. The influence of Kossel lines and standing waves on holography is also discussed. We obtain partial phase determination from experimental data obtaining the sign of the real part of the structure factor for several reciprocal lattice vectors of a vanadium crystal

Polyurethane foams obtained from residues of PET manufacturing and modified with carbon nanotubes

International Nuclear Information System (INIS)

Stiebra, L; Cabulis, U; Knite, M

2016-01-01

In this work we report the preparation of rigid microcellular polyurethane/carbon nanotube nanocomposites with different CNT loadings (0.09-0.46%) and various isocyanate indexes (110-260). Water was used as a blowing agent for samples. Density of all obtained samples – 200 ± 10 kg/m 3 . Electrical properties, as well as heat conductivity, cellular structure and mechanical properties of these nanocomposites were investigated. (paper)

Polyurethane foams obtained from residues of PET manufacturing and modified with carbon nanotubes

Science.gov (United States)

Stiebra, L.; Cabulis, U.; Knite, M.

2016-04-01

In this work we report the preparation of rigid microcellular polyurethane/carbon nanotube nanocomposites with different CNT loadings (0.09-0.46%) and various isocyanate indexes (110-260). Water was used as a blowing agent for samples. Density of all obtained samples - 200 ± 10 kg/m3. Electrical properties, as well as heat conductivity, cellular structure and mechanical properties of these nanocomposites were investigated.

Data analysis of a polycrystalline nickel sample obtained with neutron diffraction

International Nuclear Information System (INIS)

Parente, C.B.R.; Mazzochi, V.L.; Araujo Kaschny, J.R. de; Costa, M.S. da; Rizzo, P.; Campos, W.M.S.

1990-01-01

A simple analysis of the nickel structure was made. Neutron diffraction data were used, obtained with polycrystalline nickel placed in a cylindrical sample-holder with dimensions of 1,5cm of diameter and 5cm of height. The theoretical intensities were calculated of 3 forms: 1. without considering the temperature and obsorption effects, 2. considering only the temperature effect and 3. considering both the temperature and absorption effects. The disagreement factors found in this 3 cases were, respectively, R 1 = 13.4%, R 2 = 7,7% e R 3 = 7,5%. (L.C.)

Microencapsulation structures based on protein-coated liposomes obtained through electrospraying for the stabilization and improved bioaccessibility of curcumin.

Science.gov (United States)

Gómez-Mascaraque, Laura G; Casagrande Sipoli, Caroline; de La Torre, Lucimara Gaziola; López-Rubio, Amparo

2017-10-15

Novel food-grade hybrid encapsulation structures based on the entrapment of phosphatidylcholine liposomes, within a WPC matrix through electrospraying, were developed and used as delivery vehicles for curcumin. The loading capacity and encapsulation efficiency of the proposed system was studied, and the suitability of the approach to stabilize curcumin and increase its bioaccessibility was assessed. Results showed that the maximum loading capacity of the liposomes was around 1.5% of curcumin, although the loading capacity of the hybrid microencapsulation structures increased with the curcumin content by incorporation of curcumin microcrystals upon electrospraying. Microencapsulation of curcumin within the proposed hybrid structures significantly increased its bioaccessibility (∼1.7-fold) compared to the free compound, and could successfully stabilize it against degradation in PBS (pH=7.4). The proposed approach thus proved to be a promising alternative to produce powder-like functional ingredients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

Science.gov (United States)

Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

2016-01-01

In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

Characterization of rhenium compounds obtained by electrochemical synthesis after aging process

Energy Technology Data Exchange (ETDEWEB)

Vargas-Uscategui, Alejandro, E-mail: avargasuscat@ing.uchile.cl [Departamento de Ingeniería de Minas, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile); Mosquera, Edgar [Laboratorio de Materiales a Nanoescala, Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile); López-Encarnación, Juan M. [Department of Mathematics-Physics and Department of Chemistry, University of Puerto Rico at Cayey, 205 Ave. Antonio R. Barceló, Cayey, PR 00736, USA. (Puerto Rico); Chornik, Boris [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Blanco Encalada Av. 2008, Santiago (Chile); Katiyar, Ram S. [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico San Juan, San Juan, PR 00931-3343 (United States); Cifuentes, Luis [Departamento de Ingeniería de Minas, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Tupper Av. 2069, Santiago (Chile)

2014-12-15

The proper identification of the molecular nature of the aged rhenium compound obtained by means of electrodeposition from an alkaline aqueous electrolyte was determined. Chemical, structural and vibrational experimental characterization of the aged Re compound showed agreement with quantum-computations, thereby allowing the unambiguous identification of the Re compound as H(ReO{sub 4})H{sub 2}O. - Graphical abstract: Rhenium oxides were electrodeposited on a copper surface and after environmental aging was formed the H(ReO{sub 4})H{sub 2}O compound. The characterization of the synthesized material was made through the comparison of experimental evidence with quantum mechanical computations carried out by means of density functional theory (DFT). - Highlights: • Aged rhenium compound obtained by means of electrodeposition was studied. • The study was made by combining experimental and DFT-computational information. • The aged electrodeposited material is consistent with the H(ReO{sub 4})H{sub 2}O compound.

Structural characterization of silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Garcia, Paulo Ricardo; Sousa, Edi Carlos Pereira de; Pontuschka, Walter Maigon; Oliveira, Cristiano Luis Pinto de, E-mail: pauloricardoafg@yahoo.com.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Fisica

2016-07-01

Full text: Due to magnetic, optical and electrical properties metallic nanoparticles have been extensively studied to potential applications in biosensor production, separation of biological molecules, image techniques, drug delivery among several others. For such applications, it is crucial to have crystals with morphology and well defined structure. In this work we presented a detailed structured characterization of silver nanoparticles using small angle x-rays and light scattering methods. The comparison and correlation of these results with electron microscopy images permitted the determination of interesting structural parameters for the studied systems. The oscillations of the intensity curve of SAXS data reveal that this sample has particles with reasonable stability and well defined sizes. The mean radius obtained from the size distribution curve is in good agreement with the ones obtained by TEM images. As will be shown, the combination of several techniques and the correct analysis for the obtained experimental data provides unique information on the structure of the studied systems. (author)

Prion Fragment Peptides Are Digested with Membrane Type Matrix Metalloproteinases and Acquire Enzyme Resistance through Cu2+-Binding

Directory of Open Access Journals (Sweden)

Aya Kojima

2014-05-01

Full Text Available Prions are the cause of neurodegenerative disease in humans and other mammals. The structural conversion of the prion protein (PrP from a normal cellular protein (PrPC to a protease-resistant isoform (PrPSc is thought to relate to Cu2+ binding to histidine residues. In this study, we focused on the membrane-type matrix metalloproteinases (MT-MMPs such as MT1-MMP and MT3-MMP, which are expressed in the brain as PrPC-degrading proteases. We synthesized 21 prion fragment peptides. Each purified peptide was individually incubated with recombinant MT1-MMP or MT3-MMP in the presence or absence of Cu2+ and the cleavage sites determined by LC-ESI-MS analysis. Recombinant MMP-7 and human serum (HS were also tested as control. hPrP61-90, from the octapeptide-repeat region, was cleaved by HS but not by the MMPs tested here. On the other hand, hPrP92-168 from the central region was cleaved by MT1-MMP and MT3-MMP at various sites. These cleavages were inhibited by treatment with Cu2+. The C-terminal peptides had higher resistance than the central region. The data obtained from this study suggest that MT-MMPs expressed in the brain might possess PrPC-degrading activity.

Benefits of obtaining log data in horizontal wells in the WCSB

Energy Technology Data Exchange (ETDEWEB)

Spratt, D. [Reeves Wireline Technologies Ltd., Calgary, AB (Canada)

2001-11-01

A Compact Memory Logging (CML) system developed by Reeves Wireline Technologies was presented. It can be used to obtain log data from horizontal wells to get a better understanding of how to enhance production or completion techniques. The methods that are commonly used to obtain data from horizontal wells include measurement while drilling (MWD), logging while drilling (LWD), wet connect pipe conveyed wireline logging and CML. Each method has its unique benefits that range from information on lithology, rock parameters and fluid interfaces. Reeves has been using wireless pipe conveyed CML over the past two years. The log data includes array induction, dual spaced neutron and photo density porosity, Pe, gamma ray, compensated sonic and hose size caliper. Reeves CML is smaller, easily conveyed and has an unprecedented capability to bend and is considered to be well suited for both newly and previously drilled horizontal wells that require remedial assessment. The tool can be used to determine reservoir quality and boundaries, establish zone structures, or identify fluid interfaces for strategic planning of completions and stimulations. This paper presented examples of logs on some horizontal wells that indicate the value of obtaining log data. Reeves CML is considered to be economically and operationally ideal, particularly since data from the CML includes depth of investigation. 5 figs.

Nitrogen-doping effects on the growth, structure and electrical performance of carbon nanotubes obtained by spray pyrolysis method

Energy Technology Data Exchange (ETDEWEB)

Ionescu, Mihnea Ioan; Zhang Yong; Li Ruying [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada); Abou-Rachid, Hakima [Defense Research and Development Canada - Valcartier, 2459 Boulevard PieXI Nord, Quebec, QC G3J 1X5 (Canada); Sun Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada)

2012-03-01

Vertically aligned nitrogen-doped carbon nanotubes (CNTs) with modulated nitrogen content have been synthesized in a large scale by using spray pyrolysis chemical vapor deposition technique. The effects of nitrogen doping on the growth, structure and electrical performance of carbon nanotubes have been systematically examined. Field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman techniques have been employed to characterize the morphology, composition, and vibrational properties of nanotubes. The results indicate that the nitrogen incorporation significantly influences the growth rate, morphology, size and structure of nanotubes. Electrical measurement investigation of the nanotubes indicates that the change in electrical resistance increases with temperature and pressure as the nitrogen concentration increases inside the tubes. This work presents a versatile, safe, and easy way to scale up route of growing carbon nanotubes with controlled nitrogen content and modulated structure, and may provide an insight in developing various nitrogen-doped carbon-based nanodevices.

Microstructure Investigation of 13Cr-2Mo ODS Steel Components Obtained by High Voltage Electric Discharge Compaction Technique

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Igor Bogachev

2015-11-01

Full Text Available Refractory oxide dispersion strengthened 13Cr-2Mo steel powder was successfully consolidated to near theoretical density using high voltage electric discharge compaction. Cylindrical samples with relative density from 90% to 97% and dimensions of 10 mm in diameter and 10–15 mm in height were obtained. Consolidation conditions such as pressure and voltage were varied in some ranges to determine the optimal compaction regime. Three different concentrations of yttria were used to identify its effect on the properties of the samples. It is shown that the utilized ultra-rapid consolidation process in combination with high transmitted energy allows obtaining high density compacts, retaining the initial structure with minimal grain growth. The experimental results indicate some heterogeneity of the structure which may occur in the external layers of the tested samples due to various thermal and electromagnetic in-processing effects. The choice of the optimal parameters of the consolidation enables obtaining samples of acceptable quality.

Microstructure Investigation of 13Cr-2Mo ODS Steel Components Obtained by High Voltage Electric Discharge Compaction Technique.

Science.gov (United States)

Bogachev, Igor; Yudin, Artem; Grigoryev, Evgeniy; Chernov, Ivan; Staltsov, Maxim; Khasanov, Oleg; Olevsky, Eugene

2015-11-02

Refractory oxide dispersion strengthened 13Cr-2Mo steel powder was successfully consolidated to near theoretical density using high voltage electric discharge compaction. Cylindrical samples with relative density from 90% to 97% and dimensions of 10 mm in diameter and 10-15 mm in height were obtained. Consolidation conditions such as pressure and voltage were varied in some ranges to determine the optimal compaction regime. Three different concentrations of yttria were used to identify its effect on the properties of the samples. It is shown that the utilized ultra-rapid consolidation process in combination with high transmitted energy allows obtaining high density compacts, retaining the initial structure with minimal grain growth. The experimental results indicate some heterogeneity of the structure which may occur in the external layers of the tested samples due to various thermal and electromagnetic in-processing effects. The choice of the optimal parameters of the consolidation enables obtaining samples of acceptable quality.

Prion search and cellular prion protein expression in stranded dolphins.

Science.gov (United States)

Di Guardo, G; Cocumelli, C; Meoli, R; Barbaro, K; Terracciano, G; Di Francesco, C E; Mazzariol, S; Eleni, C

2012-01-01

The recent description of a prion disease (PD) case in a free-ranging bottlenose dolphin (Tursiops truncatus) prompted us to carry out an extensive search for the disease-associated isoform (PrPSc) of the cellular prion protein (PrPC) in the brain and in a range of lymphoid tissues from 23 striped dolphins (Stenella coeruleoalba), 5 bottlenose dolphins and 2 Risso s dolphins (Grampus griseus) found stranded between 2007 and 2012 along the Italian coastline. Three striped dolphins and one bottlenose dolphin showed microscopic lesions of encephalitis, with no evidence of spongiform brain lesions being detected in any of the 30 free-ranging cetaceans investigated herein. Nevertheless, we could still observe a prominent PrPC immunoreactivity in the brain as well as in lymphoid tissues from these dolphins. Although immunohistochemical and Western blot investigations yielded negative results for PrPSc deposition in all tissues from the dolphins under study, the reported occurrence of a spontaneous PD case in a wild dolphin is an intriguing issue and a matter of concern for both prion biology and intra/inter-species transmissibility, as well as for cetacean conservation medicine.

Prion infections and anti-PrP antibodies trigger converging neurotoxic pathways.

Directory of Open Access Journals (Sweden)

Uli S Herrmann

2015-02-01

Full Text Available Prions induce lethal neurodegeneration and consist of PrPSc, an aggregated conformer of the cellular prion protein PrPC. Antibody-derived ligands to the globular domain of PrPC (collectively termed GDL are also neurotoxic. Here we show that GDL and prion infections activate the same pathways. Firstly, both GDL and prion infection of cerebellar organotypic cultured slices (COCS induced the production of reactive oxygen species (ROS. Accordingly, ROS scavenging, which counteracts GDL toxicity in vitro and in vivo, prolonged the lifespan of prion-infected mice and protected prion-infected COCS from neurodegeneration. Instead, neither glutamate receptor antagonists nor inhibitors of endoplasmic reticulum calcium channels abolished neurotoxicity in either model. Secondly, antibodies against the flexible tail (FT of PrPC reduced neurotoxicity in both GDL-exposed and prion-infected COCS, suggesting that the FT executes toxicity in both paradigms. Thirdly, the PERK pathway of the unfolded protein response was activated in both models. Finally, 80% of transcriptionally downregulated genes overlapped between prion-infected and GDL-treated COCS. We conclude that GDL mimic the interaction of PrPSc with PrPC, thereby triggering the downstream events characteristic of prion infection.

Defining sporadic Creutzfeldt-Jakob disease strains and their transmission properties

Science.gov (United States)

Bishop, Matthew T.; Will, Robert G.; Manson, Jean C.

2010-01-01

The biological determinants of the phenotypic variation in sporadic Creutzfeldt-Jakob disease (sCJD) are unknown. To categorize sCJD cases, the prion protein (PrP) codon 129 genotype and the biochemical characteristics of the disease-associated form of PrP (PrPSc) can be combined to form six subgroups (MM1, MM2, MV1, MV2, VV1, and VV2). This classification largely correlates with the known variation in the clinical and pathological features of sCJD, with the MM1 and MV1 cases representing the “classic” phenotype of sCJD. To address how this classification relates to different strains of sCJD we have inoculated each subgroup of sCJD to a panel of mice expressing different forms of the human PRNP gene (129MM, 129VV, and 129MV). We have established that all subtypes are transmissible to at least one genotype of mouse, and both agent and host factors determine transmission efficiency and the form of PrPSc deposited in the brain. Moreover, we have identified four distinct strains of sCJD using our in vivo strain typing panel. PMID:20547859

Synthesis and characterization of carbon fibers obtained through plasma techniques

International Nuclear Information System (INIS)

Valdivia B, M.

2005-01-01

The study of carbon, particularly the nano technology is a recent field, the one which has important implications in the science of new materials. It investigation is of great interest for industries producers of ceramic, metallurgy, electronic, energy storage, biomedicine, among others. The diverse application fields are a reason at national as international level, so that many works are focused in the production of nano fibers of carbon. The Thermal plasma applications laboratory (LAPT) of the National Institute of Nuclear Research (ININ), it is carrying out works about carbon nano technology. The present work has as purpose to carry out the synthesis and characterization of the carbon nano fibers which are obtained by electric arch of alternating current (CA) to high frequencies and by a plasma gun of non transferred arch, where are used hydrocarbons like benzene, methane, acetylene like carbon source and ferrocene, nickel, yttrium and cerium oxide like catalysts. For both techniques its were thought about a relationship among hydrocarbon-catalyst that it favored to the nano fibers production. The obtained product of each experiment outlined it was analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD), analysis with those were obtained pictures and diffraction graphs, which were observed to arrive to one conclusion on the operation conditions, same analysis with those were characterized the tests carried out according to the nano structures formation of carbon. (Author)

SAXS study of silica sols, gels and glasses obtained by the sol gel process

International Nuclear Information System (INIS)

Santos, D.I. dos; Aegerter, M.A.

1988-01-01

Systematic SAXS studies have been performed at the LURE Synchrotron, Orsay, using an intense beam of point like cross-section to obtain information about the sol -> humid gel -> dried gel -> silica glass transformation. The intensity curves have been analysed in term of power law in log-log plots, whose exponent is related to mass and surface fractal dimensions of the structure. It was found that almost all phases present fractal structures and for the case of basic gels, is of hierarchical nature. The aerogels are formed by a dense matrix, with a smooth surface and exhibit a very narrow auto-similarity range that gives a mass fractal dimension. (author) [pt

On the energy distribution profile of interface states obtained by taking into account of series resistance in Al/TiO{sub 2}/p-Si (MIS) structures

Energy Technology Data Exchange (ETDEWEB)

Pakma, O., E-mail: osman@pakma.co [Department of Physics, Faculty of Sciences and Arts, Batman University, Batman (Turkey); Serin, N.; Serin, T. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Tandogan, Ankara (Turkey); Altindal, S. [Physics Department, Faculty of Arts and Sciences, Gazi University, Teknikokullar, 06500 Ankara (Turkey)

2011-02-15

The energy distribution profile of the interface states (N{sub ss}) of Al/TiO{sub 2}/p-Si (MIS) structures prepared using the sol-gel method was obtained from the forward bias current-voltage (I-V) characteristics by taking into account both the bias dependence of the effective barrier height ({phi}{sub e}) and series resistance (R{sub s}) at room temperature. The main electrical parameters of the MIS structure such as ideality factor (n), zero-bias barrier height ({phi}{sub b0}) and average series resistance values were found to be 1.69, 0.519 eV and 659 {Omega}, respectively. This high value of n was attributed to the presence of an interfacial insulator layer at the Al/p-Si interface and the density of interface states (N{sub ss}) localized at the Si/TiO{sub 2} interface. The values of N{sub ss} localized at the Si/TiO{sub 2} interface were found with and without the R{sub s} at 0.25-E{sub v} in the range between 8.4x10{sup 13} and 4.9x10{sup 13} eV{sup -1} cm{sup -2}. In addition, the frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/{omega}-V) characteristics of the structures have been investigated by taking into account the effect of N{sub ss} and R{sub s} at room temperature. It can be found out that the measured C and G/{omega} are strongly dependent on bias voltage and frequency. -- Research highlights: {yields}We successfully fabricated Al/TiO{sub 2}/p-Si device with interlayer by a sol-gel method. The facts: (i) that the technology of the fabrication of a Al/TiO{sub 2}/p-Si MIS structure much simpler and economical than that for the Si p-n junction and (b) the main advantages of TiO{sub 2} films are low densities of the surface states when compared to SiO{sub 2}.

Oceanic Geoid and Tides Obtained from GEOS-3 Satellite Data in the Northwestern Atlantic Ocean

Science.gov (United States)

Won, I. J.; Miller, L. S.

1978-01-01

Two sets of GEO-3 altimeter data which fall within about a 2.5 degree width are analyzed for ocean geoid and tides. One set covers a linear path from Newfoundland to Cuba and the other from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M sub 2 O sub 1, S sub 2, and K sub 1, are obtained along the two strips. The results demonstrate convergent solutions for all forty cases and show, within expectation, fair agreement with those obtained from the MODE deep-sea tide gauge. It is also shown that the oceanic geoid obtained through this analysis can potentially improve the short wavelength structure over existing geoid models.

Structural and magnetic properties Co_3O_4 obtained by the coprecipitation

International Nuclear Information System (INIS)

Junior, M.E.; Junior, F.A.; Hernandez, E.P.; Barbosa, F.C.G.; Paulo, V.I.M.; Junior, J.N.A.; Almeida, J.C.

2016-01-01

Full text: The study shows a structural and magnetic properties of cobalt oxide Co3O4 doped with Cr as a function of the parameters adopted during the synthesis by chemical co-precipitation were flowing neutralizing NaOH and calcination temperature to 800 °C and 1000 °C. First, a series of samples of this oxide in which the flow was changed neutralization of the NaOH solution was generated. Thermal treatments were carried out at 800 °C and 1000 °C in anticipation of changing voltages on the network, average crystal size, etc. XRD observed in this case that the major phase and Co3O4 was found that the change of flow, the average crystallite size of network parameters and changes suffered distorted. In magnetic measurements MxT for samples to 800 °C and 1000 °C we observed behavioral evidence of a ferri / ferromagnetic-paramagnetic transition. On the other hand, the Curie-Weiss parameter was found negative for all samples associated with the major phase Co3O4 antiferromagnetic. Thus, we could correlate these phenomena the possible presence of phase clusters / nanoclusters amorphous ferri / ferromagnetic with CoCr2O4 / CrO2 generated with the incorporation of Cr under different NaOH flows. These coupling steps leading to the observed behavior. Have the MXH measures to 1000 °C in 50K presented a characteristic hysteresis loop system ferri / ferromagnetic well pronounced and could associate this, beyond the coupling phase, the fact that higher temperatures increase the grain size decreasing the surface anisotropy and favoring phases ferri / ferromagnetic. We are convinced that the results of our research is an important contribution to the field. (author)

X-ray absorption investigation of titanium oxynitride nanoparticles obtained from laser pyrolysis

International Nuclear Information System (INIS)

Simon, Pardis; March, Katia; Stéphan, Odile; Leconte, Yann; Reynaud, Cécile; Herlin-Boime, Nathalie; Flank, Anne-Marie

2013-01-01

Highlights: • Original Ti(O,N) nanoparticles with a TiO FCC structure were synthesized by laser pyrolysis. • EELS and XAS allows to demonstrate that the nanoparticles are a solid solution of N and O in Ti. • Upon heat treatment, oxidation occurs from the surface with survival of FCC contribution till 400 °C. • Optical properties (absorption in the visible range) can be adjusted through the control of oxidation state. - Abstract: This work presents a structural study by X-ray Absorption Spectroscopy (XAS) and Electron Energy-Loss Spectroscopy (EELS) of complex titanium oxynitride nanoparticles (Ti(O,N)), synthesized by laser pyrolysis from titanium tetraisopropoxide and ammonia as precursors. Previous structural characterizations obtained by XRD and XPS have shown that the nanoparticles present a TiO type face-centered cubic (FCC) structure but with three different oxidation degree for titanium. The synthesis of this kind of titanium oxide or oxynitride nanoparticles is very unusual. Moreover, their properties are highly dependent of their structure. EELS spectrum-imaging data were therefore used for mapping the different chemical species. These measurements reveal that the nanoparticles are composed of a FCC solid solution of nitrogen and oxygen in titanium. The local structure around Ti was then studied. XANES measurements show an absorption threshold corresponding to a global valence state between Ti 3+ and Ti 4+ , with a pre-edge structure characteristic of a mix between a face-centered cubic (FCC) structure and a disordered TiO 2 structure whereas the EXAFS signal is dominated by the contribution of the FCC structure. Oxidative heat-treatments have been performed from 250 to 450 °C in order to follow the transition towards the dioxide phase. EELS measurements show that the oxidation occurs from the surface of the nanoparticles. XAS show that this transition does not involve any other crystallographic phase than TiO 2 , mainly in its anatase form, and

Understanding the structure

Science.gov (United States)

David J. Nowak

1994-01-01

Urban forests are complex ecosystems created by the interaction of anthropogenic and natural processes. One key to better management of these systems is to understand urban forest structure and its relationship to forest functions. Through sampling and inventories, urban foresters often obtain structural information (e.g., numbers, location, size, and condition) on...

InP and GaAs characterization with variable stoichiometry obtained by molecular spray

Science.gov (United States)

Massies, J.; Linh, N. T.; Olivier, J.; Faulconnier, P.; Poirier, R.

1979-01-01

Both InP and GaAs surfaces were studied in parallel. A molecular spray technique was used to obtain two semiconductor surfaces with different superficial compositions. The structures of these surfaces were examined by electron diffraction. Electron energy loss was measured spectroscopically in order to determine surface electrical characteristics. The results are used to support conclusions relative to the role of surface composition in establishing a Schottky barrier effect in semiconductor devices.

The choice of strategy of development of the enterprise entering into the integrated structure on the basis of obtaining additional competitive benefits by the enterprise

Directory of Open Access Journals (Sweden)

A. I. Khorev

2017-01-01

Full Text Available In article process of the choice of strategy of development of the enterprise, entering into the integrated structure (IS taking into account a possibility of obtaining additional competitive benefits by the enterprise from this occurrence is considered. The enterprises as a part of IS has to use a possibility of realization of effect of a synergy. In relation to the enterprise which is in IS, the synergy has not one concept, but three interrelations, different according to types, between the enterprises, namely: material, non-material and competitive. Such opinion of M. Porter shares most of the experts working in the sphere of strategic management. Realization of a synergy allows to improve overall performance not only IS (2 + 2 = 5 in general, but also and separately the enterprises entering IS. Overall performance of the enterprises improves thanks to obtaining additional competitive benefits by the enterprises in the form of decrease in expenses and differentiation of production that is realized by means of competitive strategy. Realization of effect of a synergy thanks to establishment of interrelations, as a rule, is followed also by increase in production of the enterprises entering IS that can be realized by means of growth strategy. Thus, it is desirable to develop strategy of development of the enterprise entering IS as the combined strategy consisting of two strategy: competitive and growth. The matrix of alternative strategy of development of the enterprise entering IS in the form of combinations competitive and strategy of growth, and also model of the choice of the similar combined strategy taking into account a possibility of obtaining additional competitive benefits by the enterprise is given in article. For an assessment of competitive advantages of the enterprise as a part of IS by means of ball estimates of experts the technique of a similar assessment, and a matrix of the arising interrelations of the enterprises in IS is

Prion Protein and Aging

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Lisa eGasperini

2014-08-01

Full Text Available The cellular prion protein (PrPC has been widely investigated ever since its conformational isoform, the prion (or PrPSc, was identified as the etiological agent of prion disorders. The high homology shared by the PrPC-encoding gene among mammals, its high turnover rate and expression in every tissue strongly suggest that PrPC may possess key physiological functions. Therefore, defining PrPC roles, properties and fate in the physiology of mammalian cells would be fundamental to understand its pathological involvement in prion diseases. Since the incidence of these neurodegenerative disorders is enhanced in aging, understanding PrPC functions in this life phase may be of crucial importance. Indeed, a large body of evidence suggests that PrPC plays a neuroprotective and antioxidant role. Moreover, it has been suggested that PrPC is involved in Alzheimer disease, another neurodegenerative pathology that develops predominantly in the aging population. In prion diseases, PrPC function is likely lost upon protein aggregation occurring in the course of the disease. Additionally, the aging process may alter PrPC biochemical properties, thus influencing its propensity to convert into PrPSc. Both phenomena may contribute to the disease development and progression. In Alzheimer disease, PrPC has a controversial role because its presence seems to mediate β-amyloid toxicity, while its down-regulation correlates with neuronal death. The role of PrPC in aging has been investigated from different perspectives, often leading to contrasting results. The putative protein functions in aging have been studied in relation to memory, behavior and myelin maintenance. In aging mice, PrPC changes in subcellular localization and post-translational modifications have been explored in an attempt to relate them to different protein roles and propensity to convert into PrPSc. Here we provide an overview of the most relevant studies attempting to delineate PrPC functions and

Na+/K+-ATPase is present in scrapie-associated fibrils, modulates PrP misfolding in vitro and links PrP function and dysfunction.

Directory of Open Access Journals (Sweden)

James F Graham

Full Text Available Transmissible spongiform encephalopathies are characterised by widespread deposition of fibrillar and/or plaque-like forms of the prion protein. These aggregated forms are produced by misfolding of the normal prion protein, PrP(C, to the disease-associated form, PrP(Sc, through mechanisms that remain elusive but which require either direct or indirect interaction between PrP(C and PrP(Sc isoforms. A wealth of evidence implicates other non-PrP molecules as active participants in the misfolding process, to catalyse and direct the conformational conversion of PrP(C or to provide a scaffold ensuring correct alignment of PrP(C and PrP(Sc during conversion. Such molecules may be specific to different scrapie strains to facilitate differential prion protein misfolding. Since molecular cofactors may become integrated into the growing protein fibril during prion conversion, we have investigated the proteins contained in prion disease-specific deposits by shotgun proteomics of scrapie-associated fibrils (SAF from mice infected with 3 different strains of mouse-passaged scrapie. Concomitant use of negative control preparations allowed us to identify and discount proteins that are enriched non-specifically by the SAF isolation protocol. We found several proteins that co-purified specifically with SAF from infected brains but none of these were reproducibly and demonstrably specific for particular scrapie strains. The α-chain of Na(+/K(+-ATPase was common to SAF from all 3 strains and we tested the ability of this protein to modulate in vitro misfolding of recombinant PrP. Na(+/K(+-ATPase enhanced the efficiency of disease-specific conversion of recombinant PrP suggesting that it may act as a molecular cofactor. Consistent with previous results, the same protein inhibited fibrillisation kinetics of recombinant PrP. Since functional interactions between PrP(C and Na(+/K(+-ATPase have previously been reported in astrocytes, our data highlight this molecule as

Prion diseases: immunotargets and therapy

Directory of Open Access Journals (Sweden)

Burchell JT

2016-06-01

Full Text Available Jennifer T Burchell, Peter K Panegyres Neurodegenerative Disorders Research Pty Ltd, West Perth, Western Australia, Australia Abstract: Transmissible spongiform encephathalopathies or prion diseases are a group of neurological disorders characterized by neuronal loss, spongiform degeneration, and activation of astrocytes or microglia. These diseases affect humans and animals with an extremely high prevalence in some species such as deer and elk in North America. Although rare in humans, they result in a devastatingly swift neurological progression with dementia and ataxia. Patients usually die within a year of diagnosis. Prion diseases are familial, sporadic, iatrogenic, or transmissible. Human prion diseases include Kuru, sporadic, iatrogenic, and familial forms of Creutzfeldt–Jakob disease, variant Creutzfeldt–Jakob disease, Gerstmann–Sträussler–Scheinker disease, and fatal familial insomnia. The causative agent is a misfolded version of the physiological prion protein called PrPSc in the brain. There are a number of therapeutic options currently under investigation. A number of small molecules have had some success in delaying disease progression in animal models and mixed results in clinical trials, including pentosan polysulfate, quinacrine, and amphotericin B. More promisingly, immunotherapy has reported success in vitro and in vivo in animal studies and clinical trials. The three main branches of immunotherapy research are focus on antibody vaccines, dendritic cell vaccines, and adoptive transfer of physiological prion protein-specific CD4+ T-lymphocytes. Vaccines utilizing antibodies generally target disease-specific epitopes that are only exposed in the misfolded PrPSc conformation. Vaccines utilizing antigen-loaded dendritic cell have the ability to bypass immune tolerance and prime CD4+ cells to initiate an immune response. Adoptive transfer of CD4+ T-cells is another promising target as this cell type can orchestrate the

Structural Health Monitoring Based on Combined Structural Global and Local Frequencies

Directory of Open Access Journals (Sweden)

Jilin Hou

2014-01-01

Full Text Available This paper presents a parameter estimation method for Structural Health Monitoring based on the combined measured structural global frequencies and structural local frequencies. First, the global test is experimented to obtain the low order modes which can reflect the global information of the structure. Secondly, the mass is added on the member of structure to increase the local dynamic characteristic and to make the member have local primary frequency, which belongs to structural local frequency and is sensitive to local parameters. Then the parameters of the structure can be optimized accurately using the combined structural global frequencies and structural local frequencies. The effectiveness and accuracy of the proposed method are verified by the experiment of a space truss.

Emission and structure varieties in ZnO:Ag nanorods obtained by ultrasonic spray pyrolysis

International Nuclear Information System (INIS)

Lozada, E Velázquez; Torchynska, T V; Espinola, J L Casas

2014-01-01

Scanning electronic microscopy (SEM), X ray diffraction (XRD) and photoluminescence (PL) have been applied to the study of the structural and optical properties of ZnO nanocrystals prepared by the ultrasonic spray pyrolysis (USP) at different temperatures. The variation of temperatures and times at the growth of ZnO films permits modifying the ZnO phase from the amorphous to crystalline, to change the size of ZnO nanocrystals (NCs), as well as to vary their photoluminescence spectra. The study has revealed three types of PL bands in ZnO NCs: defect related emission, the near-band-edge (NBE) PL, related to the LO phonon replica of free exciton (FE) recombination, and FE second-order diffraction peaks. The PL bands related to the LO phonon replica of FE in PL spectra measured at room temperature testify on the high quality of ZnO films prepared by the USP technology.

Red, green, and blue lanthanum phosphate phosphors obtained via surfactant-controlled hydrothermal synthesis

International Nuclear Information System (INIS)

Sousa Filho, Paulo C. de; Serra, Osvaldo A.

2009-01-01

A new solution route for the obtainment of highly pure luminescent rare-earth orthophosphates in hydrothermal conditions was developed. By starting from soluble precursors (lanthanide tripolyphosphato complexes, i.e. with P 3 O 10 5- as a complexing agent and as an orthophosphate source) and by applying surfactants in a water/toluene medium, the precipitations are confined to reverse micelle structures, thus yielding nanosized and homogeneous orthophosphates. The method was employed to obtain lanthanide-activated lanthanum phosphates, which can be applied as red (LaPO 4 :Eu 3+ ), green (LaPO 4 :Ce 3+ ,Tb 3+ ) and blue (LaPO 4 :Tm 3+ ) phosphors. The produced materials were analyzed by powder X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and luminescence spectroscopy (emission, excitation, lifetimes and chromaticity coordinates).

Fracture behaviour of Cu-Al-Ni shape memory alloys obtained by powder metallurgy

International Nuclear Information System (INIS)

Rodriguez, P. P.; Perez-Saez, R. B.; Recarte, V.; San Juan, J.M.; Ruano, O. A.; No, M. L.

2001-01-01

Polycrystalline Cu-Al-Ni shape memory alloys have been scarcely employed for technological applications due to their high brittleness. The development of a new elaboration technique based on powder metallurgy has recently overcome this problem, through the improvement of the ductility of the produced alloys without affecting its shape memory properties. The fracture behaviour of an alloy obtained using the elaboration technique has been studied by means of Scanning Electron Microscopy and mechanical testing. The results show a ductile fracture with a maximum strain close to 13%, which is the best fracture behaviour obtained for Cu-Al-Ni polycrystals. The microstructure of such alloys ha been studied by means of Transmission Electron Microscopy, showing a poligonyzed structure in which martensite plated passing through the subboundaries easily. (Author) 19 refs

The comparison of two methods to obtain human oral keratinocytes in primary culture

International Nuclear Information System (INIS)

Klingbeil, Maria Fatima Guarizo

2006-01-01

The therapeutic procedures frequently used in oral treatments for the pathological diseases are surgical, resulting in failures of the mucosal continuity.The possibility to obtain transplantable oral epithelia from an in vitro cell culture opens new utilization perspectives not only to where it comes from, but also as a reconstructive material for other parts of the human body, such as: urethra, epithelia corneo-limbal, cornea, ocular surface. Many researchers still use controversial methods for obtaining cells. It was therefore evaluated and compared the efficiency in both methods: enzymatic and direct explant to obtain oral keratinocytes from human oral mucosa. Fragments of intra oral epithelial tissues from healthy human subjects, undergoing dental surgeries, were donated to the research project. The keratinocytes were cultivated over a feeder-layer from a previously irradiated 3T3 Swiss albino fibroblasts. In this study it was compared the time needed in the cell obtention, the best cell amount between both methods, the life-span, the cell capacity to form an in vitro epithelia and its morphologic structure. The results in the assessment of both methods have shown the possibility to obtain keratinocytes from a small oral fragment, but at the same time we may verify the advantages and peculiar restrictions for each one of both analyzed methods. (author)

Molecular chaperone assisted expression systems: obtaining pure soluble and active recombinant proteins for structural and therapeutic purposes

CSIR Research Space (South Africa)

Makhoba, XH

2015-09-01

Full Text Available For many years recombinant protein production has been at the center of biosciences used for structural and therapeutic purposes. The production of recombinant proteins in foreign host system such as E. coli has been a biggest challenge. This has...

Investigating the conformational stability of prion strains through a kinetic replication model.

Directory of Open Access Journals (Sweden)

Mattia Zampieri

2009-07-01

Full Text Available Prion proteins are known to misfold into a range of different aggregated forms, showing different phenotypic and pathological states. Understanding strain specificities is an important problem in the field of prion disease. Little is known about which PrP(Sc structural properties and molecular mechanisms determine prion replication, disease progression and strain phenotype. The aim of this work is to investigate, through a mathematical model, how the structural stability of different aggregated forms can influence the kinetics of prion replication. The model-based results suggest that prion strains with different conformational stability undergoing in vivo replication are characterizable in primis by means of different rates of breakage. A further role seems to be played by the aggregation rate (i.e. the rate at which a prion fibril grows. The kinetic variability introduced in the model by these two parameters allows us to reproduce the different characteristic features of the various strains (e.g., fibrils' mean length and is coherent with all experimental observations concerning strain-specific behavior.

Cooling rate effects on structure of amorphous graphene

International Nuclear Information System (INIS)

Van Hoang, Vo

2015-01-01

Simple monatomic amorphous 2D models with Honeycomb structure are obtained from 2D simple monatomic liquids with Honeycomb interaction potential (Rechtsman et al., Phys. Rev. Lett. 95, 228301 (2005)) via molecular dynamics (MD) simulations. Models are observed by cooling from the melt at various cooling rates. Temperature dependence of thermodynamic and structural properties including total energy, mean ring size, mean coordination number is studied in order to show evolution of structure and thermodynamics upon cooling from the melt. Structural properties of the amorphous Honeycomb structures are studied via radial distribution function (RDF), coordination number and ring distributions together with 2D visualization of the atomic configurations. Amorphous Honeycomb structures contain a large amount of structural defects including new ones which have not been previously reported yet. Cooling rate dependence of structural properties of the obtained amorphous Honeycomb structures is analyzed. Although amorphous graphene has been proposed theoretically and/or recently obtained by the experiments, our understanding of structural properties of the system is still poor. Therefore, our simulations highlight the situation and give deeper understanding of structure and thermodynamics of the glassy state of this novel 2D material

Biodegradable, pH-sensitive chitosan beads obtained under microwave radiation for advanced cell culture.

Science.gov (United States)

Piątkowski, Marek; Janus, Łukasz; Radwan-Pragłowska, Julia; Bogdał, Dariusz; Matysek, Dalibor

2018-04-01

A new type of promising chitosan beads with advanced properties were obtained under microwave radiation according to Green Chemistry principles. Biomaterials were prepared using chitosan as raw material and glutamic acid/1,5-pentanodiol mixture as crosslinking agents. Additionally beads were modified with Tilia platyphyllos extract to enhance their antioxidant properties. Beads were investigated over their chemical structure by FT-IR analysis. Also their morphology has been investigated by SEM method. Additionally swelling capacity of the obtained hydrogels was determined. Lack of cytotoxicity has been confirmed by MTT assay. Proliferation studies were carried out on L929 mouse fibroblasts. Advanced properties of the obtained beads were investigated by studying pH sensitivity and antioxidant properties by DPPH method. Also susceptibility to degradation and biodegradation by Sturm Test method was evaluated. Results shows that proposed chitosan beads and their eco-friendly synthesis method can be applied in cell therapy and tissue engineering. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and characterization of lead zirconate titanate powders obtained by the oxidant peroxo method

International Nuclear Information System (INIS)

Camargo, Emerson R.; Leite, Edson R.; Longo, Elson

2009-01-01

Lead zirconate titanate (PbZr 1-x Ti x O 3 ) was synthesized by the 'oxidant peroxo method (OPM)' with 'x' between 0.25 and 0.50. Titanium metal was dissolved into a hydrogen peroxide/ammonia aqueous solution, followed by the addition of lead and zirconium nitrate solution. The amorphous precipitated precursor obtained was crystallized by heat treatment between 400 and 1000 deg. C. Images of transmission microscopy showed spherical particles with average diameter between 20 and 60 nm, and the presence of necks between particles treated at 700 deg. C. All of the unpressed powders were characterized by X-ray diffractometry and FT-Raman spectroscopy. Powder samples with 'x' up to 0.35 showed rhombohedral structure when treated at temperatures higher than 500 deg. C, and tetragonal structure when 'x' was higher than 0.40. Analysis of XRD and Raman spectroscopy of the precursor powders showed amorphous-like structures, however powders treated at 400 deg. C showed a structure identified as an intermediate pyrochlore phase, independently of the Zr and Ti mole ratio

Tin dioxide nanostructured thin films obtained through polymeric precursor method

Directory of Open Access Journals (Sweden)

Marcelo Antônio Dal Santos

2012-11-01

Full Text Available Tin dioxide (SnO2 nanostructured thin films with low proportion of defects and low roughness were produced through the systematic control of temperature and viscosity of the precursor solutions used for thin films deposition. These solutions were obtained through the citrate method and the films were deposited through the ‘dip-coating’ technique on glass substrate and after thermal treatment at 470ºC/4h, they were characterized both structurally and morphologically through the X-ray diffractometry, optic microscopy, scanning electronic microscopy, atomic force microscopy, X-ray fluorescence, UV-Vis absorption spectroscopy and X-ray excited photoelectrons spectroscopy. The film thickness was obtained through scanning electronic microscopy of the films cross-section and correlated to the proportion of Sn and Si obtained through X-ray fluorescence. X-ray diffractometry of the films revealed the presence of peaks corresponding to the SnO2 crystalline phase, overlapping a wide peak between 20 and 30º (2?, characteristic of the glass substrate. Optic microscopy, Scanning electronic microscopy and atomic force microscopy revealed homogeneous films, with low roughness, suitable to several applications such as sensors and transparent electrodes. It could be observed through the UV-Vis absorption analysis that the films presented high optical transparency and ‘band gap’ energy 4.36 eV. The X-ray excited photoelectron spectroscopy confirmed the presence of SnO2, as well as traces of the elements present in the glass substrate and residual carbon from the thermal treatment of the films.

Physicochemical properties of manganese oxides obtained via the sol-gel method: The reduction of potassium permanganate by polyvinyl alcohol

Science.gov (United States)

Ivanets, A. I.; Prozorovich, V. G.; Krivoshapkina, E. F.; Kuznetsova, T. F.; Krivoshapkin, P. V.; Katsoshvili, L. L.

2017-08-01

Experimental data on the sol-gel synthesis of manganese oxides formed during the reduction of potassium permanganate by polyvinyl alcohol in an aqueous medium are presented. The physicochemical properties of the obtained manganese oxide systems that depend on the conditions of the synthesis are studied by means of DTA, XRD, SEM, and the low temperature adsorption-desorption of nitrogen. It is found that the obtained samples have a mesoporous structure and predominantly consist of double potassium-manganese oxide K2Mn4O8 with a tunnel structure and impurities of oxides such as α-MnO2, MnO, α-Mn2O3, and Mn5O8. It is shown that the proposed method of synthesis allows us to regulate the size and volume of mesopores and, to a lesser extent, the texture of the obtained oxides, which can be considered promising sorbents for the selective extraction of strontium and cesium ions from multicomponent aqueous solutions.

Nature Inspired Plasmonic Structures: Influence of Structural Characteristics on Sensing Capability

KAUST Repository

Perozziello, Gerardo; Candeloro, Patrizio; Coluccio, Maria; Das, Godind; Rocca, Loredana; Pullano, Salvatore; Fiorillo, Antonino; De Stefano, Mario; Di Fabrizio, Enzo M.

2018-01-01

Surface enhanced Raman scattering (SERS) is a powerful analytical technique that allows the enhancement of a Raman signal in a molecule or molecular assemblies placed in the proximity of nanostructured metallic surfaces, due to plasmonic effects. However, laboratory methods to obtain of these prototypes are time-consuming, expensive and they do not always lead to the desired result. In this work, we analyse structures existing in nature that show, on a nanoscale, characteristic conformations of photonic crystals. We demonstrate that these structures, if covered with gold, change into plasmonic nanostructures and are able to sustain the SERS effect. We study three different structures with this property: opal, a hydrated amorphous form of silica (SiO·nHO); diatoms, a kind of unicellular alga; and peacock tail feather. Rhodamine 6G (down to 10 M) is used to evaluate their capability to increase the Raman signal. These results allow us to define an alternative way to obtain a high sensitivity in Raman spectroscopy, currently achieved by a long and expensive technique, and to fabricate inexpensive nanoplasmonic structures which could be integrated into optical sensors.

Nature Inspired Plasmonic Structures: Influence of Structural Characteristics on Sensing Capability

KAUST Repository

Perozziello, Gerardo

2018-04-26

Surface enhanced Raman scattering (SERS) is a powerful analytical technique that allows the enhancement of a Raman signal in a molecule or molecular assemblies placed in the proximity of nanostructured metallic surfaces, due to plasmonic effects. However, laboratory methods to obtain of these prototypes are time-consuming, expensive and they do not always lead to the desired result. In this work, we analyse structures existing in nature that show, on a nanoscale, characteristic conformations of photonic crystals. We demonstrate that these structures, if covered with gold, change into plasmonic nanostructures and are able to sustain the SERS effect. We study three different structures with this property: opal, a hydrated amorphous form of silica (SiO·nHO); diatoms, a kind of unicellular alga; and peacock tail feather. Rhodamine 6G (down to 10 M) is used to evaluate their capability to increase the Raman signal. These results allow us to define an alternative way to obtain a high sensitivity in Raman spectroscopy, currently achieved by a long and expensive technique, and to fabricate inexpensive nanoplasmonic structures which could be integrated into optical sensors.

Purification and characterization of a gentiohexaose obtained from botryosphaeran by partial acid hydrolysis

International Nuclear Information System (INIS)

Silva, Iara Ribeiro; Monteiro, Nilson Kobori; Martinez, Paula Felippe; Izeli, Nataly Lino; Vasconcelos, Ana Flora Dalberto; Cardoso, Marilsa de Stefani; Silva, Maria de Lourdes Corradi da; Silva, Gil Valdo Jose da; Moraes, Luis Alberto Beraldo de

2008-01-01

A hexa-oligosaccharide was obtained by partial acid hydrolysis from botryosphaeran, an exopolysaccharide (EPS) β(1→3; 1→6)-D-glucan type, produced by the ascomyceteous fungus Botryosphaeria rhodina. The oligosaccharide was purified by gel filtration and charcoal-Celite column chromatography and the analysis was followed by HPAEC/ PAD. The structure was determined by NMR spectroscopy and mass spectrometry, which showed that the oligosaccharide consists of six β-D-glucopyranosyl units O-6 substituted (gentiohexaose). (author)

Structure of simple liquids; Structure des liquides simples

Energy Technology Data Exchange (ETDEWEB)

Blain, J F [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1969-07-01

The results obtained by application to argon and sodium of the two important methods of studying the structure of liquids: scattering of X-rays and neutrons, are presented on one hand. On the other hand the principal models employed for reconstituting the structure of simple liquids are exposed: mathematical models, lattice models and their derived models, experimental models. (author) [French] On presente d'une part les resultats obtenus par application a l'argon et au sodium des deux principales methodes d'etude de la structure des liquides: la diffusion des rayons X et la diffusion des neutrons; d'autre part, les principaux modeles employes pour reconstituer la structure des liquides simples sont exposes: modeles mathematiques, modeles des reseaux et modeles derives, modeles experimentaux. (auteur)

Structural biology by NMR: structure, dynamics, and interactions.

Directory of Open Access Journals (Sweden)

Phineus R L Markwick

2008-09-01

Full Text Available The function of bio-macromolecules is determined by both their 3D structure and conformational dynamics. These molecules are inherently flexible systems displaying a broad range of dynamics on time-scales from picoseconds to seconds. Nuclear Magnetic Resonance (NMR spectroscopy has emerged as the method of choice for studying both protein structure and dynamics in solution. Typically, NMR experiments are sensitive both to structural features and to dynamics, and hence the measured data contain information on both. Despite major progress in both experimental approaches and computational methods, obtaining a consistent view of structure and dynamics from experimental NMR data remains a challenge. Molecular dynamics simulations have emerged as an indispensable tool in the analysis of NMR data.

Obtaining shale oil suitable for lighting

Energy Technology Data Exchange (ETDEWEB)

Giraudel, M

1851-11-12

Treats with sulphuric acid and then with soda, obtaining 57 per cent of products suitable for lighting in place of the usual 35 to 40 per cent as obtained by present processes. The product has a less disagreeable odor.

Red mercuric iodide crystals obtained by isothermal solution evaporation: Characterization for mammographic X-ray imaging detectors

Energy Technology Data Exchange (ETDEWEB)

Caldeira, A.M.F.; Ugucioni, J.C.; Mulato, M.

2014-02-11

Millimeter-sized mercury iodide crystals were obtained by the isothermal evaporation technique using dimethylformamide (DMF), diethyl-ether/DMF mixture and THF. Different concentrations (18 mM and 400 mM) and solution temperature (25–80 °C) were used to obtain varied evaporation rates (0.1×10{sup −4}–5000×10{sup −4} ml/h). Different crystal sizes and shapes were obtained by changing solvents, mixture and initial solution volume. According to X-ray diffraction the samples are monocrystalline. The top surface was investigated by SEM. Optical band-gaps above 2 eV were obtained from photoacoustic spectroscopy. Photoluminescence spectra indicated band-to-band electronic transitions, and the presence of sub-band gap states. Excitons, structural defects and the presence of impurities are discussed and correlated to the electrical measurements. Crystals obtained using pure DMF as solvent showed better general properties, including under the exposure to mammographic X-ray energy range that led to sensibility of about 25 μC/Rcm{sup 2}.

Numerically stable fluid–structure interactions between compressible flow and solid structures

KAUST Repository

Grétarsson, Jón Tómas

2011-04-01

We propose a novel method to implicitly two-way couple Eulerian compressible flow to volumetric Lagrangian solids. The method works for both deformable and rigid solids and for arbitrary equations of state. The method exploits the formulation of [11] which solves compressible fluid in a semi-implicit manner, solving for the advection part explicitly and then correcting the intermediate state to time tn+1 using an implicit pressure, obtained by solving a modified Poisson system. Similar to previous fluid-structure interaction methods, we apply pressure forces to the solid and enforce a velocity boundary condition on the fluid in order to satisfy a no-slip constraint. Unlike previous methods, however, we apply these coupled interactions implicitly by adding the constraint to the pressure system and combining it with any implicit solid forces in order to obtain a strongly coupled, symmetric indefinite system (similar to [17], which only handles incompressible flow). We also show that, under a few reasonable assumptions, this system can be made symmetric positive-definite by following the methodology of [16]. Because our method handles the fluid-structure interactions implicitly, we avoid introducing any new time step restrictions and obtain stable results even for high density-to-mass ratios, where explicit methods struggle or fail. We exactly conserve momentum and kinetic energy (thermal fluid-structure interactions are not considered) at the fluid-structure interface, and hence naturally handle highly non-linear phenomenon such as shocks, contacts and rarefactions. © 2011 Elsevier Inc.

PrPSc detection in formalin-fixed paraffin-embedded tissue by ELISA

Directory of Open Access Journals (Sweden)

Nicholson Eric M

2011-10-01

Full Text Available Abstract Background Formalin-fixed paraffin-embedded tissue is regularly employed in the diagnosis of transmissible spongiform encephalopathies (TSE by immunohistochemistry (IHC, the standard by which all other TSE diagnostic protocols are judged. While IHC affords advantages over diagnostic approaches that typically utilize fresh or frozen tissue, such as Western blot and ELISA, the process of fixing, staining, and analyzing individual sections by hand does not allow for rapid or high throughput screening. However, preservation of tissues in formalin is not dependent upon the availability of refrigeration. Findings Formalin-fixed paraffin-embedded tissues from TSE transmission studies of scrapie in sheep, chronic wasting disease in white-tailed deer or transmissible mink encephalopathy in cattle were cut at 5 μm thickness. Samples containing the tissue equivalent of as little as one 5 μm section can be used to readily discriminate positive from negative samples. Conclusions This approach cannot replace IHC but may be used along with IHC as both a more rapid and readily high throughput screen where fresh or frozen tissues are not available or impractical.

Recent researches concerning the obtaining of functional textiles based on conductive yarns

Science.gov (United States)

Leon, A. L.; Manea, L. R.; Hristian, L.

2016-08-01

Modem textile industry is influenced both by consumers' lifestyle and by novel materials. Functional textiles can be included into the group of technical textiles. The functional activity can be shortly interpreted as "sense - react - adapt" to the environment while traditional materials meet only passive protective role, a barrier between body and environment. Functional materials cross the conventional limits because they are designed for specific performances, being part of domains as: telemedicine, medicine, aeronautics, biotechnology, nanotechnology, protective clothes, sportswear, etc. This paper highlights the most recent developments in the field of using conductive yarns for obtaining functional textiles. Conductive fabrics can be done by incorporating into the textile structure the conductive fibers / yarns. The technologies differ from embroidering, sewing, weaving, knitting to braiding and obtaining nonwovens. The conductive fabrics production has a quickly growth because it is a high demand for these textiles used for data transfer in clothing, monitoring vital signs, germ-free garments, brain-computer interface, etc. Nowadays it is of high interest surface treatments of fibers/yarns which can be considered as a novel kind of textile finishing. There are presented some researches related to obtaining conductive yarns by coating PET and PP yarns with PANi conductive polymer.

Use of Repeated Fluoropolymer Suspensions to Obtain Composite Electrochemical Coating Based on Zinc

Science.gov (United States)

Musikhina, T. A.; Zemtsova, E. A.; Fuks, C. L.

2017-11-01

This article deals with the issues of utilization of the waste products of fluoropolymers, namely, the suspensions of fluoroplasts that have lost their consumer properties. Such waste is recommended to be used as a filler of zinc coatings to provide increased corrosion resistance. Using the method of mathematical planning of the experiment, the authors establish the optimal compositions of galvanizing chloride-ammonium electrolytes to obtain the corrosion-resistant composite electrochemical coatings (CEC) of zinc-fluoropolymer. As a result, coatings with a finely crystalline structure were obtained differing in the distribution pattern on the surface of the samples and depending on the variation in the zinc concentration in the electrolytes. The samples of steel reinforcement with the zinc-fluoropolymer coating were tested on corrosion resistance. The increase of anticorrosive properties in CEC zinc-fluoropolymer and a slight decrease in microhardness were indicated.

Hybrid modelling of soil-structure interaction for embedded structures

International Nuclear Information System (INIS)

Gupta, S.; Penzien, J.

1981-01-01

The basic methods currently being used for the analysis of soil-structure interaction fail to properly model three-dimensional embedded structures with flexible foundations. A hybrid model for the analysis of soil-structure interaction is developed in this investigation which takes advantage of the desirable features of both the finite element and substructure methods and which minimizes their undesirable features. The hybrid model is obtained by partitioning the total soil-structure system into a nearfield and a far-field with a smooth hemispherical interface. The near-field consists of the structure and a finite region of soil immediately surrounding its base. The entire near-field may be modelled in three-dimensional form using the finite element method; thus, taking advantage of its ability to model irregular geometries, and the non-linear soil behavior in the immediate vicinity of the structure. (orig./WL)

Structural and electrochemical characterization of calcium cobaltites (Ca{sub 3}Co{sub 4}O{sub 9}) obtained by the modified Pechini Method; Caracterizacao estrutural e eletroquimica de cobaltita de calcio (Ca{sub 3}Co{sub 4}O{sub 9}) obtida pelo Metodo Pechini modificado

Energy Technology Data Exchange (ETDEWEB)

Silva, R.M.; Aquino, F. de M.; Macedo, D. A. de, E-mail: rinaldo_mendesa@hotmail.com [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil)

2016-07-01

This work deals with the synthesis and characterization of calcium cobaltite (Ca{sub 3}Co{sub 4}O{sub 9}, C349), a p-type semiconductor with high Seebeck coefficient (S), high electrical conductivity and low thermal conductivity that has emerged as thermoelectric material. The synthesis method used to obtain the compound C349 uses commercial gelatin as complexing and polymerizing agent. The obtained material was characterized by X-ray diffraction with Rietveld refinement of the diffraction data. The results indicated that the modified Pechini method using gelatin allows to obtain powders of calcium cobaltite (with monoclinic structure) associated with a small content (2% by volume) of Co{sub 3}O{sub 4} with cubic structure. Impedance spectroscopy measurements in air indicated that the composite C349/Co{sub 3}O{sub 4} is a promising material for use as solid oxide fuel cell cathode.(author)

Structure and thermodynamics of molten salts

International Nuclear Information System (INIS)

Papatheodorou, G.N.

1983-01-01

This chapter investigates single-component molten salts and multicomponent salt mixtures. Molten salts provide an important testing ground for theories of liquids, solutions, and plasmas. Topics considered include molten salts as liquids (the pair potential, the radial distribution function, methods of characterization), single salts (structure, thermodynamic correlations), and salt mixtures (the thermodynamics of mixing; spectroscopy and structure). Neutron and X-ray scattering techniques are used to determine the structure of molten metal halide salts. The corresponding-states theory is used to obtain thermodynamic correlations on single salts. Structural information on salt mixtures is obtained by using vibrational (Raman) and electronic absorption spectroscopy. Charge-symmetrical systems and charge-unsymmetrical systems are used to examine the thermodynamics of salt mixtures

Hadron structure functions

International Nuclear Information System (INIS)

Martin, F.

1981-03-01

The x dependence of hadron structure functions is investigated. If quarks can exist in very low mass states (10 MeV for d and u quarks) the pion structure function is predicted to behave like (1-x) and not (1-x) 2 in a x-region around 1. Relativistic and non-relativistic quark bound state pictures of hadrons are considered together with their relation with the Q 2 evolution of structure functions. Good agreement with data is in general obtained

Chemical structures and thermal properties of polyesters obtained from different samples of bio diesel epoxidized; Estruturas quimicas e propriedades termicas de poliesteres obtidos a partir de diferentes tipos de biodiesel epoxidado

Energy Technology Data Exchange (ETDEWEB)

Samios, Dimitrios; Reiznautt, Quelen B.; Nicolau, Aline; Martini, Denise D.; Chagas, Arthur L. das, E-mail: dsamios@iq.ufrgs.b [Universidade Federal do Rio Grande do Sul (IQ/UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica. Lab. de Instrumentacao e Dinamica Molecular

2009-07-01

In this work new structures from oligo esters and polyesters from different oils (olive oil, sunflower oil and linseed oil) were synthesized and characterized. Oligo esters and polyesters were synthesized from the reaction of fatty acid methyl epoxy-esters, obtained from different oils, with cis-1,2-cyclohexanedicarboxylic anhydride in the presence of triethylamine (TEA). Different amounts of the resin 1,4-butanediol diglycidyl ether (BDGE) were added in order to increase the capacity of crosslinking. The molar ratio of BDGE used in system was between 0 and 0.066. The intermediate structures, as well as the oligo esters and polyesters produced, were analyzed by using Fourier Transform Infrared Spectroscopy and Nuclear Magnetic Resonance ({sup 1}H - NMR). The thermal behavior of the products was realized through differential scanning calorimetry and Thermogravimetric analyses. The presence of BDGE in the materials chains increases the bonding capacity resulting in a higher molecular weight material which presents good thermal stability. (author)

Obtaining and characterizing the binary compound Zr3Pt

International Nuclear Information System (INIS)

Tanoni, Diego; Arico, Sergio F; Alonso, Paula R

2006-01-01

The equilibrium phases in the Zr - Pt binary system are not fully defined. Experiences carried out from 0% to 50% at. Pt in the equilibrium diagram of Zr-Pt phases in 2001 revealed the presence of the intermetallic compounds Zr 2 Pt, Zr 5 Pt 3 , ZrPt (already previously identified by other authors) and a compound of 25% composition at Pt with an unidentified crystalline structure. This experimental work aims to fill out the information on this compound by characterizing its crystallography. An alloy was produced in the binary system Zr-Pt with a composition close to the stoichiometry by casting in an arc furnace, and was studied by optic and electronic metallography. The identification and crystallographic characterization of the phase is based on measurements of composition in electronic microwave and on analysis of spectrums obtained by X-ray diffraction. The results are presented, showing the presence in the cast structure of the solid solution zircon phases (hexagonal) and of the inter-metallic compound Zr 5 Pt 3 . These two phases were identified in the X-ray diffraction diagrams as well as the presence of other reflections that are associated with the inter-metallic Zr 3 Pt. The measurements of composition consistently reveal the presence of a phase of 25%at Pt composition. The structure's morphology shown in metallographies reveals the occurrence of a eutectic type transformation during cooling. We conclude that the formation of the phase sought in a composition 25 % at Pt should occur at temperatures below the eutectic transformation, and could be a peritectoid formation as was previously proposed. Therefore, the sample needs to be homogenized with thermal treatments that favor the formation and stabilization of the compound (CW)

IMMUNOLOGICAL STUDY OF SPONGIFORM ENCEPHALOPATHIES

OpenAIRE

J. Meenupriya

2013-01-01

Spongiform encephalopathies, categorized as a subclass of neuro-degenerative diseases and commonly known as prion diseases, are a group of progressive conditions that affect the brain and nervous system of many animals, including humans. Prion diseases are common among cannibalistic communities; further research has revealed that the infected or malformed prion protein (named PrPsc) spreads its virulence to the normal, healthy prion protein (named PrPc) when people consume...

Distinct prion-like strains of amyloid beta implicated in phenotypic diversity of Alzheimer's disease.

Science.gov (United States)

Cohen, Mark; Appleby, Brian; Safar, Jiri G

2016-01-01

Vast evidence on human prions demonstrates that variable disease phenotypes, rates of propagation, and targeting of distinct brain structures are determined by unique conformers (strains) of pathogenic prion protein (PrP(Sc)). Recent progress in the development of advanced biophysical tools that inventory structural characteristics of amyloid beta (Aβ) in the brain cortex of phenotypically diverse Alzheimer's disease (AD) patients, revealed unique spectrum of oligomeric particles in the cortex of rapidly progressive cases, implicating these structures in variable rates of propagation in the brain, and in distict disease manifestation. Since only ∼30% of phenotypic diversity of AD can be explained by polymorphisms in risk genes, these and transgenic bioassay data argue that structurally distinct Aβ particles play a major role in the diverse pathogenesis of AD, and may behave as distinct prion-like strains encoding diverse phenotypes. From these observations and our growing understanding of prions, there is a critical need for new strain-specific diagnostic strategies for misfolded proteins causing these elusive disorders. Since targeted drug therapy can induce mutation and evolution of prions into new strains, effective treatments of AD will require drugs that enhance clearance of pathogenic conformers, reduce the precursor protein, or inhibit the conversion of precursors into prion-like states.

Comparison of optical properties of Eu3+ ions in the silica gel glasses obtained by different preparation techniques

International Nuclear Information System (INIS)

Legendziewicz, J.; Sokolnicki, J.; Keller, B.; Borzechowska, M.; Strek, W.

1996-01-01

Silica-gel glasses doped with Eu 3+ ions were obtained by different preparation techniques. The absorption, emission and excitation spectra of the obtained glasses were measured in the range of 77-300 K. The energy levels diagrams of Eu 3+ ions were derived. An intensity analysis of f-f transitions was performed. In particular, polymeric structure behaviour of europium compounds entrapped in silica gel glasses was temperature controlled during the preparation of glasses. Their optical properties were investigated. (author)

Development of a Computer Application to Simulate Porous Structures

Directory of Open Access Journals (Sweden)

S.C. Reis

2002-09-01

Full Text Available Geometric modeling is an important tool to evaluate structural parameters as well as to follow the application of stereological relationships. The obtention, visualization and analysis of volumetric images of the structure of materials, using computational geometric modeling, facilitates the determination of structural parameters of difficult experimental access, such as topological and morphological parameters. In this work, we developed a geometrical model implemented by computer software that simulates random pore structures. The number of nodes, number of branches (connections between nodes and the number of isolated parts, are obtained. Also, the connectivity (C is obtained from this application. Using a list of elements, nodes and branches, generated by the software, in AutoCAD® command line format, the obtained structure can be viewed and analyzed.

38 CFR 21.5725 - Obtaining benefits.

Science.gov (United States)

2010-07-01

... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Obtaining benefits. 21... benefits. (a) Actions required of the individual. In order to obtain benefits under the educational assistance and subsistence allowance program, an individual must— (1) File a claim for benefits with VA, and...

Obtaining multifunctional composites using styrofoam recycling: methylene blue adsorption

International Nuclear Information System (INIS)

Silva, T.H. da; Ferreira, B.F.; Faria, E.H. de; Ciuffi, K.J.; Calefi, P.S.

2011-01-01

There is high risk of environmental contamination by the textile industry if the generated waste is disposed into water streams and rivers. Another sector responsible for the generation of large amounts of waste is the styrofoam industry, since styrofoam is employed in various areas for packaging production. Therefore, today there is constant search for sustainable economic growth by means of materials recycling and reduction of residual pollutants. In this context, the present work aims to promote styrofoam recycling with its further utilization in the production of a kaolin-styrofoam composite for application as adsorbent of methylene blue originated from textile industry effluents. This adsorption is investigated in a column system, by exploiting the adsorptive properties of kaolin, such as large surface area and chemical and structural characteristics. The obtained materials were characterized by thermogravimetric analysis, X-ray diffraction, and UV-visible absorption spectroscopy. (author)

Robustness Analysis of Typologies of Reciprocal Timber Structures

DEFF Research Database (Denmark)

Kirkegaard, Poul Henning; Parigi, Dario

2013-01-01

to the future development of typologies of reciprocal timber structures. The paper concludes that these kinds of structures can have a potential as long span timber structures in real projects if they are carefully designed with respect to the overall robustness strategies.......Robustness of structural systems has obtained a renewed interest due to a much more frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure. In order to minimise the likelihood of such disproportionate structural failures many modern building...... codes consider the need for robustness in structures and provides strategies and methods to obtain robustness. Therefore a structural engineer may take necessary steps to design robust structures that are insensitive to accidental circumstances. The present paper outlines robustness issues related...

Treating shale oil to obtain sulfonates

Energy Technology Data Exchange (ETDEWEB)

Schaeffer, H

1921-01-21

The process shows as its principal characteristics: (1) treating the oil with chlorsulfonic acid at a temperature of about 100/sup 0/C; (2) the transformation of the sulfonic acid obtained into salts; (3) as new industrial products, the sulfonates obtained and their industrial application as disinfectants for hides and wood.

Synthesis and characterization of electrical conducting nanoporous carbon structures

International Nuclear Information System (INIS)

El Mir, L.; Kraiem, S.; Bengagi, M.; Elaloui, E.; Ouederni, A.; Alaya, S.

2007-01-01

Nanoporous organic xerogel compounds were prepared by sol-gel method from pyrogallol-formaldehyde (PF) mixtures in water using perchloric acid as catalyst. The preparation conditions of electrical conducting carbon (ECC) structures were explored by changing the pyrolysis temperature. The effect of this preparation parameters on the structural and electrical properties of the obtained ECCs were studied, respectively, by thermogravimetric analysis (TGA), nitrogen adsorption isotherms, IR spectroscopy and electrical conductivity measurements. The analysis of the obtained results revealed that, the polymeric insulating phase was transformed progressively with pyrolysis temperature into carbon conducting phase; this means the formation of long continuous conducting path for charge carriers when the carbon microparticles inside the structure agglomerated with thermal treatment and the samples exhibited tangible percolation behaviour where the percolation threshold can be determined by pyrolysis temperature. The temperature-dependent conductivity and the I(V) characteristics of the obtained ECC structures show a non-ohmic behaviour. The results obtained from TGA and differential thermal analyser (DTA) thermograms, scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs, IR spectroscopy and X-ray diffraction revealed that, the obtained ECC structures consist of amorphous and nanoporous electrical conducting carbon materials

Chemically deposited In2S3–Ag2S layers to obtain AgInS2 thin films by thermal annealing

International Nuclear Information System (INIS)

Lugo, S.; Peña, Y.; Calixto-Rodriguez, M.; López-Mata, C.; Ramón, M.L.; Gómez, I.; Acosta, A.

2012-01-01

Highlights: ► We obtained polycrystalline silver indium sulfide thin films through the annealing of chemically deposited In 2 S 3 –Ag 2 S films. ► According to XRD chalcopyrite structure of AgInS 2 was obtained. ► AgInS 2 thin film has a band gap of 1.86 eV and a conductivity value of 1.2 × 10 −3 (Ω cm) −1 . - Abstract: AgInS 2 thin films were obtained by the annealing of chemical bath deposited In 2 S 3 –Ag 2 S layers at 400 °C in N 2 for 1 h. According to the XRD and EDX results the chalcopyrite structure of AgInS 2 has been obtained. These films have an optical band gap, E g , of 1.86 eV and an electrical conductivity value of 1.2 × 10 −3 (Ω cm) −1 .

Synthesis and characterization of lead zirconate titanate powders obtained by the oxidant peroxo method

Energy Technology Data Exchange (ETDEWEB)

Camargo, Emerson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos SP, 13565-905 (Brazil)], E-mail: camargo@ufscar.br; Leite, Edson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod. Washington Luis km 235, CP 676, Sao Carlos SP, 13565-905 (Brazil)], E-mail: derl@power.ufscar.br; Longo, Elson [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP, Sao Paulo State University Rua Francisco Degni, CP 355 Araraquara SP, 14801-907 Brazil (Brazil)], E-mail: elson@iq.unesp.br

2009-02-05

Lead zirconate titanate (PbZr{sub 1-x}Ti{sub x}O{sub 3}) was synthesized by the 'oxidant peroxo method (OPM)' with 'x' between 0.25 and 0.50. Titanium metal was dissolved into a hydrogen peroxide/ammonia aqueous solution, followed by the addition of lead and zirconium nitrate solution. The amorphous precipitated precursor obtained was crystallized by heat treatment between 400 and 1000 deg. C. Images of transmission microscopy showed spherical particles with average diameter between 20 and 60 nm, and the presence of necks between particles treated at 700 deg. C. All of the unpressed powders were characterized by X-ray diffractometry and FT-Raman spectroscopy. Powder samples with 'x' up to 0.35 showed rhombohedral structure when treated at temperatures higher than 500 deg. C, and tetragonal structure when 'x' was higher than 0.40. Analysis of XRD and Raman spectroscopy of the precursor powders showed amorphous-like structures, however powders treated at 400 deg. C showed a structure identified as an intermediate pyrochlore phase, independently of the Zr and Ti mole ratio.

Automated MAD and MIR structure solution

International Nuclear Information System (INIS)

Terwilliger, Thomas C.; Berendzen, Joel

1999-01-01

A fully automated procedure for solving MIR and MAD structures has been developed using a scoring scheme to convert the structure-solution process into an optimization problem. Obtaining an electron-density map from X-ray diffraction data can be difficult and time-consuming even after the data have been collected, largely because MIR and MAD structure determinations currently require many subjective evaluations of the qualities of trial heavy-atom partial structures before a correct heavy-atom solution is obtained. A set of criteria for evaluating the quality of heavy-atom partial solutions in macromolecular crystallography have been developed. These have allowed the conversion of the crystal structure-solution process into an optimization problem and have allowed its automation. The SOLVE software has been used to solve MAD data sets with as many as 52 selenium sites in the asymmetric unit. The automated structure-solution process developed is a major step towards the fully automated structure-determination, model-building and refinement procedure which is needed for genomic scale structure determinations

Nature Inspired Plasmonic Structures: Influence of Structural Characteristics on Sensing Capability

Directory of Open Access Journals (Sweden)

Gerardo Perozziello

2018-04-01

Full Text Available Surface enhanced Raman scattering (SERS is a powerful analytical technique that allows the enhancement of a Raman signal in a molecule or molecular assemblies placed in the proximity of nanostructured metallic surfaces, due to plasmonic effects. However, laboratory methods to obtain of these prototypes are time-consuming, expensive and they do not always lead to the desired result. In this work, we analyse structures existing in nature that show, on a nanoscale, characteristic conformations of photonic crystals. We demonstrate that these structures, if covered with gold, change into plasmonic nanostructures and are able to sustain the SERS effect. We study three different structures with this property: opal, a hydrated amorphous form of silica (SiO2·nH2O; diatoms, a kind of unicellular alga; and peacock tail feather. Rhodamine 6G (down to 10−12 M is used to evaluate their capability to increase the Raman signal. These results allow us to define an alternative way to obtain a high sensitivity in Raman spectroscopy, currently achieved by a long and expensive technique, and to fabricate inexpensive nanoplasmonic structures which could be integrated into optical sensors.

Morphology, Microstructure, and Hydrogen Content of Carbon Nanostructures Obtained by PECVD at Various Temperatures

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M. Acosta Gentoiu

2017-01-01

Full Text Available Carbon nanostructures were obtained by acetylene injection into an argon plasma jet in the presence of hydrogen. The samples were synthesized in similar conditions, except that the substrate deposition temperatures TD were varied, ranging from 473 to 973 K. A strong dependence of morphology, structure, and graphitization upon TD was found. We obtained vertical aligned carbon nanotubes (VA-CNTs at low temperatures as 473 K, amorphous carbon nanoparticles (CNPs at temperatures from about 573 to 673 K, and carbon nanowalls (CNWs at high temperatures from 773 to 973 K. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, elastic recoil detection analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to substantiate the differences in these material types. It is known that hydrogen concentration modifies strongly the properties of the materials. Different concentrations of hydrogen-bonded carbon could be identified in amorphous CNP, VA-CNT, and CNW. Also, the H : C ratios along depth were determined for the obtained materials.

Spinel Li2CoTi3O8 nanometer obtained for application as pigment

International Nuclear Information System (INIS)

Costa de Camara, M. S.; Alves Pimentel, L.; Longo, E.; Nobrega Azevedo, L. da; Araujo Melo, D. M. de

2016-01-01

Pigments are used in ceramics, cosmetics, inks, and other applications widely materials. To this must be single and easily reproducible. Moreover, the pigments obtained in the nanoscale are more stable, reproducible and highlight color in small amounts compared with those obtained in micrometer scale. The mixed oxides with spinel structures AB 2 O 4 have important applications, including: pigments, refractories, catalytic and electronic ceramics. In this context, the aim of this work was the preparation of powder Li 2 CoTi 3 O 8 spinel phase with nanometer particle size of the polymeric precursor method (Pechini) and characterization by means of thermal analysis (TG/DTA) X-ray diffraction (XRD), refined by the Rietveld method, BET, transmission electron microscopy (TEM), Raman and colorimetric coordinates. The pigment was obtained by heat treatment of 400 degree centigrade to 1000 degree centigrade after pyrolysis at 300 degree centigrade/1 h for removing the organic material. Li 2 CoTi 3 O 8 desired spinel phase was obtained from 500 degree centigrade, and presenting stability nanometer to about 1.300 degree centigrade. Spinel green phase introduced at temperatures in the range of 400 degree centigrade and 500 degree centigrade, and 600 degree centigrade at temperatures between blue and 1000 degree centigrade. (Author)

Influence of polystyrene addition to cellulose on chemical structure and properties of bio-oil obtained during pyrolysis

International Nuclear Information System (INIS)

Rutkowski, Piotr; Kubacki, Andrzej

2006-01-01

The cellulose (C), polystyrene (PS) and cellulose/polystyrene (C-PS) mixtures (3:1, 1:1, 1:3 w/w) were subjected to a pyrolysis process to produce bio-oil. The pyrolytic oil yield was in the range of 45.5-94.8 wt% depending on the composition of the sample. Pyrolysis of polystyrene gives the highest oil yield, whereas for cellulose, the yield of liquid products was the lowest. The basic physicochemical properties of oils are strongly influenced by the original material and do not change additively. The polystyrene addition to cellulose clearly improves the quality of the bio-oil, resulting in decreases in acid number, pour point and density. The change of color is not so distinct. The FT-IR analysis of the oils showed that the oxygen functionalities and hydrocarbons contents highly depend on the composition of the cellulose/polystyrene mixture. The fractionation of bio-oils by column chromatography using hexane and benzene was followed by GC-MS analyses. Different classes of organic compounds were identified, i.e., carboxylic acids, phenols, aldehydes, ketones, esters, ethers and unsaturated linear and cyclic hydrocarbons. The proportion of hydrocarbons increases with a decrease of the cellulose/polystyrene ratio. The obtained results indicate that during pyrolysis, not only does decomposition of cellulose and polystyrene occur, but also, reactions between products from C and PS take place. That was proved by the presence of compounds identified only in the bio-oils obtained from C-PS compositions

Electrostatic Force Microscopy of Self Assembled Peptide Structures

DEFF Research Database (Denmark)

Clausen, Casper Hyttel; Dimaki, Maria; Pantagos, Spyros P.

2011-01-01

In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures. In partic......In this report electrostatic force microscopy (EFM) is used to study different peptide self-assembled structures, such as tubes and particles. It is shown that not only geometrical information can be obtained using EFM, but also information about the composition of different structures...

Peeled Guidewire Coating with Debulked Plaque Obtained by Directional Coronary Atherectomy

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Rikuta Hamaya

2017-01-01

Full Text Available Percutaneous directional coronary atherectomy (DCA is a plaque debulking method performed in Japan, and recently a renewed DCA device has been launched. We present a case with a tight left anterior descending lesion undergoing percutaneous coronary intervention with application of DCA. After several sessions of DCA, white plaques accompanied by green, stringed materials were obtained from the device; some materials were considerably long (approximately 15 mm in length. A drug-eluting stent was subsequently implanted, and the procedure was completed successfully without any complications. The extracted plaques and artificial materials were pathologically examined, and no inflammatory changes were detected on plaques adjacent to the material. Assessing pathological findings and structure of the DCA catheter, the obtained artificial materials were considered as peeled guidewire, possibly resulting from the friction between the guidewire and metallic bearing in the housing of DCA catheter. Of note, this phenomenon has been recognized even in other DCA cases in which guidewires of the other kind are used. We report this phenomenon for the first time, warning of theoretically possible distal embolization of artificial materials caused by any debulking devices.

Cell response to nanocrystallized metallic substrates obtained through severe plastic deformation.

Science.gov (United States)

Bagherifard, Sara; Ghelichi, Ramin; Khademhosseini, Ali; Guagliano, Mario

2014-06-11

Cell-substrate interface is known to control the cell response and subsequent cell functions. Among the various biophysical signals, grain structure, which indicates the repeating arrangement of atoms in the material, has also proved to play a role of significant importance in mediating the cell activities. Moreover, refining the grain size through severe plastic deformation is known to provide the processed material with novel mechanical properties. The potential application of such advanced materials as biomedical implants has recently been evaluated by investigating the effect of different substrate grain sizes on a wide variety of cell activities. In this review, recent advances in biomedical applications of severe plastic deformation techniques are highlighted with special attention to the effect of the obtained nano/ultra-fine-grain size on cell-substrate interactions. Various severe plastic deformation techniques used for this purpose are discussed presenting a brief description of the mechanism for each process. The results obtained for each treatment on cell morphology, adhesion, proliferation, and differentiation, as well as the in vivo studies, are discussed. Finally, the advantages and challenges regarding the application of these techniques to produce multifunctional bio-implant materials are addressed.

Obtaining zeolite Y synthesized by hydrothermal treatment assisted by microwave

International Nuclear Information System (INIS)

Simoes, A.N.; Simoes, V.N.; Neiva, L.S.; Rodrigues, M.G.F.; Gama, L.; Oliveira, J. B.L.

2011-01-01

n search of new catalysts several man-made structures have been developed. The use of zeolites in catalysis is applied due to its ability to associate activity, selectivity and stability, the main conditions to have an effective catalyst. Thus, studies have been done on the hydrothermal synthesis of zeolites by microwave assisted, since the use of microwave radiation offers several advantages over conventional heating. In this context, this work aims to synthesis and characterization of zeolite Y via hydrothermal treatment in a microwave oven. The sample obtained was characterized by XRD, BET and SEM. XRD results showed the formation of zeolite Y in just 60 minutes. The sample showed high value of surface area, the latter being of 476.2 m² / g. The particles are agglomerated, but with a narrow distribution of size. (author)

1H-NMR/13C-NMR studies of branched structures in PVC obtained at atmospheric pressure

International Nuclear Information System (INIS)

Braun, D.; Holzer, G.; Hjertberg, T.

1981-01-01

The 1 H-NMR-spectra of raw poly (vinyl cloride) obtained at atmospheric pressure (U-PVC) have revealed the presence of high concentrations of branches. The content of labile chlorine was determined by reaction with phenole in order to estimate the branch points with tertiary chlorine. The branch length of reductively dehalogenated U-PVC by 13 C-NMR analysis have provided evidence for both short chain branches including chloromethyl groups and 2.4-dichloro-n-butyl groups and long chain branching. For a number of U-polymers the total amount of branching ranges from 7.5 to 13.5/1000 C. The 13 C-NMR measurements point to a ratio of methyl/butyl branches of 1:1 and short chains/long chains of 6:1. (orig.)

Crystal structure of aspartame anhydrate from powder diffraction data. Structural aspects of the dehydration process of aspartame

NARCIS (Netherlands)

Guguta, C.; Meekes, H.L.M.; Gelder, R. de

2006-01-01

Aspartame has three pseudo-polymorphic forms, two hydrates and a hemi-hydrate, for which crystal structures were determined from single-crystal diffraction data. This paper presents the crystal structure of the anhydrate, which was obtained by dehydrating the hemi-hydrate. The crystal structure of

Modal Based Fatigue Monitoring of Steel Structures

DEFF Research Database (Denmark)

Graugaard-Jensen, J.; Brincker, Rune; Hjelm, H. P.

2005-01-01

In this paper it is shown how the accumulated fatigue in steel structures can be estimated with high accuracy by continuously measuring the accelerations in a few points of the structure. First step is to obtain a good estimate of the mode shapes by performing a natural input modal analysis. The so...... by applying the mode shapes of the calibrated Finite Element model and strains are obtained using the shape functions for the actual elements. The technique has been applied on a model frame structure in the laboratory and on a wind loaded lattice pylon structure. In both cases the estimated stresses has been...

Effect of pressure on the structural properties and electronic band structure of GaSe

Energy Technology Data Exchange (ETDEWEB)

Schwarz, U.; Olguin, D.; Syassen, K. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Cantarero, A. [Department of Materials Sciences, University of Valencia, 46000 Burjasot (Spain); Hanfland, M. [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble (France)

2007-01-15

The structural properties of GaSe have been investigated up to 38 GPa by monochromatic X-ray diffraction. The onset of the phase transition from the {epsilon}-GaSe to a disordered NaCl-type structural motif is observed near 21 GPa. Using the experimentally determined lattice parameters of the layered {epsilon}-phase as input, constrained ab-initio total energy calculations were performed in order to optimize the internal structural parameters at different pressures. The results obtained for the nearest-neighbor Ga-Se distance agree with those derived from recent EXAFS measurements. In addition, information is obtained on the changes of Ga-Ga and Se-Se bond lengths which were not accessible to a direct experimental determination yet. Based on the optimized structural parameters, we report calculations of band gap changes of {epsilon}-GaSe under pressure. The optical response and electronic band structure of the metallic high-pressure phase of GaSe are discussed briefly. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Deep seismic transect across the Tonankai earthquake area obtained from the onshore- offshore wide-angle seismic study

Science.gov (United States)

Nakanishi, A.; Obana, K.; Kodaira, S.; Miura, S.; Fujie, G.; Ito, A.; Sato, T.; Park, J.; Kaneda, Y.; Ito, K.; Iwasaki, T.

2008-12-01

In the Nankai Trough subduction seismogenic zone, M8-class great earthquake area can be divided into three segments; they are source regions of the Nankai, Tonankai and presumed Tokai earthquakes. The Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. Hypocenters of these great earthquakes were usually located off the cape Shiono, Kii Peninsula, and the rupture propagated westwards and eastwards, respectively. To obtain the deep structure of the down-dip limit of around the Nankai Trough seismogenic zone, the segment boundary and first break area off the Kii Peninsula, the onshore-offshore wide-angle seismic studies was conducted in the western and eastern part of the Kii Peninsula and their offshore area in 2004 and 2006, respectively. The result of the seismic study in 2004 is mainly shown here. Structural images along the onshore and offshore profiles have already been separately obtained. In this study, an onshore-offshore integrated image of the western part of the Kii Peninsula, ~400km in a total length, is obtained from first arrival tomography and traveltime mapping of reflection phases by combining dataset of 13 land explosions, 2269 land stations, 36 OBSs and 1806 offshore airgun shots. The subduction angle of the Philippine Sea plate (PSP) gradually increases landward up to ~20-25 degree. Beneath the onshore part, the subducting PSP is estimated at ~5km shallower than that previously derived from seismicity. Low frequency earthquakes (identified and picked by Japan Meteorological Agency) are relocated around the plate interface of the subducting PSP by using the deep seismic transect obtained in this study. The offshore research is part of 'Structure research on plate dynamics of the presumed rupture zone of the Tonankai-Nankai Earthquakes' funded by Ministry of Education, Culture, Sports, Science and Technology (MEXT). The onshore research carried by the Kyoto University is part of 'Special Project for

Prions spread via the autonomic nervous system from the gut to the central nervous system in cattle incubating bovine spongiform encephalopathy.

Science.gov (United States)

Hoffmann, Christine; Ziegler, Ute; Buschmann, Anne; Weber, Artur; Kupfer, Leila; Oelschlegel, Anja; Hammerschmidt, Baerbel; Groschup, Martin H

2007-03-01

To elucidate the still-unknown pathogenesis of bovine spongiform encephalopathy (BSE), an oral BSE challenge and sequential kill study was carried out on 56 calves. Relevant tissues belonging to the peripheral and central nervous system, as well as to the lymphoreticular tract, from necropsied animals were analysed by highly sensitive immunohistochemistry and immunoblotting techniques to reveal the presence of BSE-associated pathological prion protein (PrPSc) depositions. Our results demonstrate two routes involving the autonomic nervous system through which BSE prions spread by anterograde pathways from the gastrointestinal tract (GIT) to the central nervous system (CNS): (i) via the coeliac and mesenteric ganglion complex, splanchnic nerves and the lumbal/caudal thoracic spinal cord (representing the sympathetic GIT innervation); and (ii) via the Nervus vagus (parasympathetic GIT innervation). The dorsal root ganglia seem to be subsequently affected, so it is likely that BSE prion invasion of the non-autonomic peripheral nervous system (e.g. sciatic nerve) is a secondary retrograde event following prion replication in the CNS. Moreover, BSE-associated PrPSc was already detected in the brainstem of an animal 24 months post-infection, which is 8 months earlier than reported previously. These findings are important for the understanding of BSE pathogenesis and for the development of new diagnostic strategies for this infectious disease.

Cholesterol Balance in Prion Diseases and Alzheimer’s Disease

Science.gov (United States)

Hannaoui, Samia; Shim, Su Yeon; Cheng, Yo Ching; Corda, Erica; Gilch, Sabine

2014-01-01

Prion diseases are transmissible and fatal neurodegenerative disorders of humans and animals. They are characterized by the accumulation of PrPSc, an aberrantly folded isoform of the cellular prion protein PrPC, in the brains of affected individuals. PrPC is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosyl-phosphatidyl-inositol (GPI) anchor. Specifically, it is associated with lipid rafts, membrane microdomains enriched in cholesterol and sphinoglipids. It has been established that inhibition of endogenous cholesterol synthesis disturbs lipid raft association of PrPC and prevents PrPSc accumulation in neuronal cells. Additionally, prion conversion is reduced upon interference with cellular cholesterol uptake, endosomal export, or complexation at the plasma membrane. Altogether, these results demonstrate on the one hand the importance of cholesterol for prion propagation. On the other hand, growing evidence suggests that prion infection modulates neuronal cholesterol metabolism. Similar results were reported in Alzheimer’s disease (AD): whereas amyloid β peptide formation is influenced by cellular cholesterol, levels of cholesterol in the brains of affected individuals increase during the clinical course of the disease. In this review, we summarize commonalities of alterations in cholesterol homeostasis and discuss consequences for neuronal function and therapy of prion diseases and AD. PMID:25419621

LRP1 controls biosynthetic and endocytic trafficking of neuronal prion protein

DEFF Research Database (Denmark)

Parkyn, Celia J; Vermeulen, Esmeralda G M; Mootoosamy, Roy C

2008-01-01

The trafficking of normal cellular prion protein (PrP(C)) is believed to control its conversion to the altered conformation (designated PrP(Sc)) associated with prion disease. Although anchored to the membrane by means of glycosylphosphatidylinositol (GPI), PrP(C) on neurons is rapidly and consti......The trafficking of normal cellular prion protein (PrP(C)) is believed to control its conversion to the altered conformation (designated PrP(Sc)) associated with prion disease. Although anchored to the membrane by means of glycosylphosphatidylinositol (GPI), PrP(C) on neurons is rapidly...... required for this process. Moreover, sustained inhibition of LRP1 levels by siRNA leads to the accumulation of PrP(C) in biosynthetic compartments, with a concomitant lowering of surface PrP(C), suggesting that LRP1 expedites the trafficking of PrP(C) to the neuronal surface. PrP(C) and LRP1 can be co......-immunoprecipitated from the endoplasmic reticulum in normal neurons. The N-terminal domain of PrP(C) binds to purified human LRP1 with nanomolar affinity, even in the presence of 1 microM of the LRP-specific chaperone, receptor-associated protein (RAP). Taken together, these data argue that LRP1 controls both the surface...

Cholesterol Balance in Prion Diseases and Alzheimer’s Disease

Directory of Open Access Journals (Sweden)

Samia Hannaoui

2014-11-01

Full Text Available Prion diseases are transmissible and fatal neurodegenerative disorders of humans and animals. They are characterized by the accumulation of PrPSc, an aberrantly folded isoform of the cellular prion protein PrPC, in the brains of affected individuals. PrPC is a cell surface glycoprotein attached to the outer leaflet of the plasma membrane by a glycosyl-phosphatidyl-inositol (GPI anchor. Specifically, it is associated with lipid rafts, membrane microdomains enriched in cholesterol and sphinoglipids. It has been established that inhibition of endogenous cholesterol synthesis disturbs lipid raft association of PrPC and prevents PrPSc accumulation in neuronal cells. Additionally, prion conversion is reduced upon interference with cellular cholesterol uptake, endosomal export, or complexation at the plasma membrane. Altogether, these results demonstrate on the one hand the importance of cholesterol for prion propagation. On the other hand, growing evidence suggests that prion infection modulates neuronal cholesterol metabolism. Similar results were reported in Alzheimer’s disease (AD: whereas amyloid β peptide formation is influenced by cellular cholesterol, levels of cholesterol in the brains of affected individuals increase during the clinical course of the disease. In this review, we summarize commonalities of alterations in cholesterol homeostasis and discuss consequences for neuronal function and therapy of prion diseases and AD.

Evaluation of several techniques to modify denatured muscle tissue to obtain a scaffold for peripheral nerve regeneration

NARCIS (Netherlands)

Meek, MF; den Dunnen, WFA; Schakenraad, JM; Robinson, PH

The aim of this study was to (1) evaluate the effect of several preparation techniques of denatured muscle tissue to obtain an open three-dimensional structure, and (2) test if this scaffold is suitable for peripheral nerve regeneration. Four samples (A-D) of muscle tissue specimens were evaluated

The effect of thermohydrogen treatment on the structure and properties of casts obtained from titanium alloys

International Nuclear Information System (INIS)

Il'in, A.A.; Skvortsova, S.V.; Mamonov, A.M.; Permyakova, G.V.; Kurnikov, D.A.

2002-01-01

The method based on the combination of high temperature gas-static and thermal hydrogen treatments is suggested to increase mechanical properties of cast pseudo-α and (α+β)-titanium alloys. The study is carried out using alloys VT20L, VT23L and alloy Ti-6%Al-2%Mo-4%Zr-2%Sn. It is shown that the method proposed provides the change in a cast structure, an increase in density of castings, an increase of strength properties by 10-20% and fatigue by a factor of 1.5-2 at satisfactory ductility and impact strength [ru

Study of Maxwell–Wagner (M–W) relaxation behavior and hysteresis observed in bismuth titanate layered structure obtained by solution combustion synthesis using dextrose as fuel

International Nuclear Information System (INIS)

Subohi, Oroosa; Shastri, Lokesh; Kumar, G.S.; Malik, M.M.; Kurchania, Rajnish

2014-01-01

Graphical abstract: X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T c ) to be 650 °C. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample. - Highlights: • Bi 4 Ti 3 O 12 is synthesized using solution combustion technique with dextrose as fuel. • Dextrose has high reducing capacity (+24) and generates more no. of moles of gases. • Impedance studies show that the sample follows Maxwell–Wagner relaxation behavior. • Shows lower remnant polarization due to higher c-axis ratio. - Abstract: Structural, dielectric and ferroelectric properties of bismuth titanate (Bi 4 Ti 3 O 12 ) obtained by solution combustion technique using dextrose as fuel is studied extensively in this paper. Dextrose is used as fuel as it has high reducing valancy and generates more number of moles of gases during the reaction. X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T c ) to be 650 °C. The dielectric loss is very less (tan δ < 1) at lower temperatures but increases around T c due to structural changes in the sample. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample

Structure functions and correlations in nuclei

International Nuclear Information System (INIS)

Fantoni, S.

1988-01-01

In this paper the results obtained for the static structure function S(k) and the longitudinal structure function S L (k) of 3 H, 3 He and 4 He nuclei and nuclear matter are presented and discussed. The calculations have been performed using realistic wave functions obtained from Faddeev and variational theories. The Monte Carlo method has been used to calculate the structure functions of finite systems, and the FHNC/SOC method for nuclear matter. The results for the 3 He nucleus are in agreement with the recent Saclay data. The results for nuclear matter are compared with the experimental data relative to heavier nuclei, like e.g. 40 Ca

Lightning activity and radar observations of the multicell thunderstorm system passing over Swider Observatory (Poland) on 19 July 2015 and its dynamic and electric charge structure obtained from the WRF_ELEC model

Science.gov (United States)

Kubicki, Marek; Konarski, Jerzy; Gajda, Wojciech; Barański, Piotr; Guzikowski, Jakub; Kryza, Maciej

2017-04-01

In this work we present preliminary results on the thunderstorm event at IG PAS Swider Geophysical Observatory (52.12°N, 21.25°E, geomagnetic latitude 50.5°N, near Warsaw, Poland) on 19 July 2015. The storm was caused by the abrasion of the warm front that stretched almost latitudinaly and cold front moving from the west to the east. Warm continental-tropical arrived at southern and eastern part of the country and the rest was covered by cool polar-maritime airmass. The storm had the squall-line character of approximately 100 km length and consisted of several cells, and the height of the cumulonimbus (Cb) cloud base was 1 km and top was 14 km, as inferred from the analysis of CAPPI (Constant Altitude Plan Position Indicator), CMAX (Column Maximum Display), MLVCUT (Multiple-Line Vertical Cut) radar map products from POLRAD observations at Institute of Meteorology and Water Management - National Research Institute (IMWM-NRI), Legionowo station. In our paper we have discussed the obtained results of the post-time analysis of lightning activity and radar observations of the extended multicells thunderstorm system passing over IG PAS Swider Geophysical Observatory, on 19 July 2015 together with its dynamic and electric charge structure obtained from the WRF_ELEC model. We have used the archive data from the Polish National Lightning Location and Detection System PERUN (provided by IMWM-NRI) together with radar data obtained from the Doppler meteorological radar METEOR 1500C at Legionowo. Additionally, during the approach, passing over and moving away phase of the thunderstorm system, we have gathered the simultaneous and continuous recordings of E-field, the electric conductivity of air and the independent supplementary reference lightning detections delivered by the Swider measuring station of the Local Lightning Detection Network (LLDN) operated in Warsaw region. These data have given us a new possibility to acquire many valuable information about the

Ultrastructural studies on variants of Streptomyces SP-765 obtained after gamma irradiation

International Nuclear Information System (INIS)

Spasova, D.I.; Krystev, Kh.I.; Todorov, I.O.; Dzhedzheva, G.M.; Popov, M.S.

1988-01-01

The study has been carried out with two variants of Streptomyces SP-765, gray and olygosporous, obtained after 1000 Gy gamma irradiation of spore suspension from the initial strain. The gray variant has chains of spores which are oval or oblong with rounded-off edges. Sporulation is highly inhibited in the olygosporous variant. Eleven electron-microscopic pictures of ultrathin sections from colonies of the two variants are presented. The gray variant reveals the presence of a large number of lyzed cells, spores, and scarce vegetative cells; typical of the lyzed cells are the spherical and highly osmiophilic formations on the outer and inner surface of their cytoplasmic membrane. The oligosporous variant shows lyzed cells of various sizes, cells void of content with thick walls, relativelly small number of vegetative cells and individual wall-less cells, shperoplast and protoplast formation, lamellar membrane structure of nearly all cells. Both lyzed and vegetable cells have individual anomalous form containing daughter cells. The conclusion is made that gray and oligosporous variants of Streptomyces SP-765, obtained after irradiation of its spores, possess different ultrastructural organization

Simulating the Surface Relief of Nanoaerosols Obtained via the Rapid Cooling of Droplets

Science.gov (United States)

Tovbin, Yu. K.; Zaitseva, E. S.; Rabinovich, A. B.

2018-03-01

An approach is formulated that theoretically describes the structure of a rough surface of small aerosol particles obtained from a liquid droplet upon its rapid cooling. The problem consists of two stages. In the first stage, a concentration profile of the droplet-vapor transition region is calculated. In the second stage, local fractions of vacant sites and their pairs are found on the basis of this profile, and the rough structure of a frozen droplet surface transitioning to the solid state is calculated. Model parameters are the temperature of the initial droplet and those of the lateral interaction between droplet atoms. Information on vacant sites inside the region of transition allows us to identify adsorption centers and estimate the monolayer capacity, compared to that of the total space of the region of transition. The approach is oriented toward calculating adsorption isotherms on real surfaces.

Impact of soil-structure interaction on the probabilistic frequency variation of concrete structures

International Nuclear Information System (INIS)

Hadjian, A.H.; Hamilton, C.W.

1975-01-01

Earthquake response of equipment in nuclear power plants is characterized by floor response spectra. Since these spectra peak at the natural frequencies of the structure, it is important, both from safety and cost standpoints, to determine the degree of the expected variability of the calculated structural frequencies. A previous work is extended on the variability of the natural frequencies of structures due to the variations of concrete properties and a rigorous approach is presented to evaluate frequency variations based on the probability distributions of both the structural and soil parameters and jointly determine the distributions of the natural frequencies. It is assumed that the soil-structure interaction coefficients are normally distributed. With the proper choice of coordinates, the simultaneous random variations of both the structural properties and the interaction coefficients can be incorporated in the eigenvalue problem. The key methodology problem is to obtain the probability distribution of eigenvalues of matrices with random variable elements. Since no analytic relation exists between the eigenvalues and the elements, a numerical procedure had to be designed. It was found that the desired accuracy can be best achieved by splitting the joint variation into two parts: the marginal distribution of soil variations and the conditional distribution of structural variations at specific soil fractiles. Then after calculating the actual eigenvalues at judiciously selected paired values of soil and structure parameters, this information is recombined to obtain the desired cumulative distribution of natural frequencies

Purification of alcohol obtained from molasses

Energy Technology Data Exchange (ETDEWEB)

Visnevskaya, G L; Egorov, A S; Sokol' skaya, E V

1960-01-01

A study of the composition of alcohol liquids on different plates of a fractionation column of indirect action during purification of alcohol obtained from normal and defective molasses, and from starch raw material, showed that there were two local strength minima in the lower part of the column and on the plates (adjacent and feed). Aldehydes behaved as a typical head impurity; a noticeable increase in their concentration occurred only on the highest plates in the fractionation column. In the zone of the column containing liquids of a strength of 86 to 94% alcohol by weight a sharply pronounced local maximum of ester accumulation were observed, provisionally designated as intermediate, whose presence is apparently one of the causes of the specific sharp taste of alcohol obtained from molasses. These esters hinder the obtaining of high-grade alcohols which are standard in respect to ester content and oxidizability test. Reduction with 0.05N KMnO/sub 4/ occurs most rapidly with alcohol liquids in the zone of ester accumulation; purification of alcohols obtained from grain and potato raw material resulted in no zones of ester accumulation in the column.

Response of subsystems on inelastic structures

International Nuclear Information System (INIS)

Lin, J.; Mahin, S.A.

1984-01-01

Preliminary analysis are performed to obtain insight into the seismic response of subsystems supported on simple structures that yield during severe earthquake ground motions. Current design recommendations for subsystems accounting for yielding of the supporting structures are assessed and found to be unconservative. An amplification factor is defined to quantify the effects of inelastic deformations of the supporting structure on subsystem response. Design guidelines are formulated for predicting the amplification factor based on statistical evaluation of the results generated for ten earthquake ground motions. Using these values, design floor response spectra can be obtained from conventional linear elastic floor response spectra accounting for yielding of the supporting structure without having to perform inelastic analysis. The effects of non-zero subsystem mass are examined. The recommended amplification factors are found to be applicable even when the mass of subsystem approaches that of the supporting structure

Influence of the crack propagation rate in the obtaining opening and closing stress intensity factor by finite element method

OpenAIRE

Luiz Carlos H. Ricardo; Carlos Alexandre J. Miranda

2016-01-01

Crack propagation simulation began with the development of the finite element method; the analyses were conducted to obtain a basic understanding of the crack growth. Today structural and materials engineers develop structures and materials properties using this technique as criterion design. The aim of this paper is to verify the effect of different crack propagation rates in determination of crack opening and closing stress of an ASTM specimen under a standard suspension spectrum loading fr...

High-Throughput Screening of Compounds for Anti-Transmissible Spongiform Encephalopathy Activity Using Cell-Culture and Cell-Free Models and Infected Animals

Science.gov (United States)

2008-07-01

polyphenols were selected as PrPSc inhibitors against both strains of mouse scrapie in the SCDB assay. Tannin (tannic acid), the most potent inhibitor...of human prion disease is contingent on post-mortem (or biopsy) analysis of brain, despite a number of clinical and paraclinical laboratory features... analysis of the scrapie-associated protein PrP 27-30 in water by infrared spectroscopy. Biochemistry 30, 7672–7680 (1991). The first study revealing

Prequantization andKMS structures

International Nuclear Information System (INIS)