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Sample records for als promote formation

  1. Promotion of formation of amyloid fibrils by aluminium adenosine triphosphate (AlATP).

    Science.gov (United States)

    Exley, C; Korchazhkina, O V

    2001-04-01

    The formation of amyloid fibrils is considered to be an important step in the aetiology of Alzheimer's disease and other amyloidoses. Fibril formation in vitro has been shown to depend on many different factors including modifications to the amino acid profile of fibrillogenic peptides and interactions with both large and small molecules of physiological significance. How these factors might contribute to amyloid fibril formation in vivo is not clear as very little is known about the promotion of fibril formation in undersaturated solutions of amyloidogenic peptides. We have used thioflavin T fluorescence and reverse phase high performance liquid chromatography to show that ATP, and in particular AlATP, promoted the formation of thioflavin T-reactive fibrils of beta amyloid and, an unrelated amyloidogenic peptide, amylin. Evidence is presented that induction of fibril formation followed the complexation of AIATP by one or more monomers of the respective peptide. However, the complex formed could not be identified directly and it is suggested that AlATP might be acting as a chaperone in the assembly of amyloid fibrils. The effect of AlATP was not mimicked by either AlADP or AlAMP. However, it was blocked by suramin, a P2 ATP receptor antagonist, and this has prompted us to speculate that the precursor proteins to beta amyloid and amylin may be substrates or receptors for ATP in vivo.

  2. Loss of metal ions, disulfide reduction and mutations related to familial ALS promote formation of amyloid-like aggregates from superoxide dismutase.

    Directory of Open Access Journals (Sweden)

    Zeynep A Oztug Durer

    Full Text Available Mutations in the gene encoding Cu-Zn superoxide dismutase (SOD1 are one of the causes of familial amyotrophic lateral sclerosis (FALS. Fibrillar inclusions containing SOD1 and SOD1 inclusions that bind the amyloid-specific dye thioflavin S have been found in neurons of transgenic mice expressing mutant SOD1. Therefore, the formation of amyloid fibrils from human SOD1 was investigated. When agitated at acidic pH in the presence of low concentrations of guanidine or acetonitrile, metalated SOD1 formed fibrillar material which bound both thioflavin T and Congo red and had circular dichroism and infrared spectra characteristic of amyloid. While metalated SOD1 did not form amyloid-like aggregates at neutral pH, either removing metals from SOD1 with its intramolecular disulfide bond intact or reducing the intramolecular disulfide bond of metalated SOD1 was sufficient to promote formation of these aggregates. SOD1 formed amyloid-like aggregates both with and without intermolecular disulfide bonds, depending on the incubation conditions, and a mutant SOD1 lacking free sulfhydryl groups (AS-SOD1 formed amyloid-like aggregates at neutral pH under reducing conditions. ALS mutations enhanced the ability of disulfide-reduced SOD1 to form amyloid-like aggregates, and apo-AS-SOD1 formed amyloid-like aggregates at pH 7 only when an ALS mutation was also present. These results indicate that some mutations related to ALS promote formation of amyloid-like aggregates by facilitating the loss of metals and/or by making the intramolecular disulfide bond more susceptible to reduction, thus allowing the conversion of SOD1 to a form that aggregates to form resembling amyloid. Furthermore, the occurrence of amyloid-like aggregates per se does not depend on forming intermolecular disulfide bonds, and multiple forms of such aggregates can be produced from SOD1.

  3. Synthesis of YAG:Ce3+ Phosphor by Polyacrylamide Gel Method and Promoting Action of α-Al2O3 Seed Crystal on Phase Formation

    Institute of Scientific and Technical Information of China (English)

    Li Yongxiu; Li Yinyi; Min Yulin; Wu Yanli; Cheng Changming; Zhou Xuezhen; Gu Ziying

    2005-01-01

    YAG:Ce3+ phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermediate phases, including θ-Al2O3, YAM and YAP, are formed when calcining polyacrylamide gel, however, the pure YAG phase can be formed directly when calcining polyacrylamide gel with α-Al2O3 as seed crystal. These facts show that the existence of α-Al2O3 seed crystal can block the formation of θ-Al2O3, YAM and YAP, and accelerate its reaction with Y2O3 to form YAG phase directly at lower temperature. The emission peak of prepared YAG:Ce3+ phosphor is wide with maximum at 550 nm and the exitation band has two peaks, the major one is around at 460 nm, which matches the blue emission of GaN LED and is suitable for the assemble of white LED. Some fluxes can enhance the photoluminescence intensity of phosphor particles, that can be attributed both to the improvement of crystallization processes of YAG and to the stabilization of trivalence cerium ion in YAG:Ce3+.

  4. Protective Al2O3 scale formation on NbAl3-base alloys

    Science.gov (United States)

    Doychak, J.; Hebsur, M. G.

    1991-01-01

    The oxidation of NbAl3 with additions of Cr and Y was studied to determine the mechanisms of the beneficial effects of these elements upon oxidation. Cr additions to the binary NbAl3 alloy of up to 6.8 at. percent reduced the scale growth rates and promoted alpha-Al2O3 formation over much longer times relative to binary NbAl3. A major effect of Cr is to form a layer of AlNbCr at the metal/scale interface, which is inherently more oxidation-resistant than the matrix alloy in the long term. Yttrium additions to a Cr-containing alloy improved the scale growth rate and adherence and changed the scale microstructure to mimic that of a typical protective Al2O3 scale.

  5. Promoting proximal formative assessment with relational discourse

    Science.gov (United States)

    Scherr, Rachel E.; Close, Hunter G.; McKagan, Sarah B.

    2012-02-01

    The practice of proximal formative assessment - the continual, responsive attention to students' developing understanding as it is expressed in real time - depends on students' sharing their ideas with instructors and on teachers' attending to them. Rogerian psychology presents an account of the conditions under which proximal formative assessment may be promoted or inhibited: (1) Normal classroom conditions, characterized by evaluation and attention to learning targets, may present threats to students' sense of their own competence and value, causing them to conceal their ideas and reducing the potential for proximal formative assessment. (2) In contrast, discourse patterns characterized by positive anticipation and attention to learner ideas increase the potential for proximal formative assessment and promote self-directed learning. We present an analysis methodology based on these principles and demonstrate its utility for understanding episodes of university physics instruction.

  6. Cu(II) promotes amyloid pore formation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hangyu, E-mail: hangyuz@uw.edu [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States); Rochet, Jean-Christophe [Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907 (United States); Stanciu, Lia A. [Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, IN 47907 (United States)

    2015-08-14

    The aggregation of α-synuclein is associated with dopamine neuron death in Parkinson's disease. There is controversy in the field over the question of which species of the aggregates, fibrils or protofibrils, are toxic. Moreover, compelling evidence suggested the exposure to heavy metals to be a risk of PD. Nevertheless, the mechanism of metal ions in promoting PD remains unclear. In this research, we investigated the structural basis of Cu(II) induced aggregation of α-synuclein. Using transmission electron microscopy experiments, Cu(II) was found to promote in vitro aggregation of α-synuclein by facilitating annular protofibril formation rather than fibril formation. Furthermore, neuroprotective baicalein disaggregated annular protofibrils accompanied by considerable decrease of β-sheet content. These results strongly support the hypothesis that annular protofibrils are the toxic species, rather than fibrils, thereby inspiring us to search novel therapeutic strategies for the suppression of the toxic annular protofibril formation. - Highlights: • Cu(II) promoted the annular protofibril formation of α-synuclein in vitro. • Cu(II) postponed the in vitro fibrillization of α-synuclein. • Neuroprotective baicalein disaggregated annular protofibrils.

  7. Spaceflight promotes biofilm formation by Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Wooseong Kim

    Full Text Available Understanding the effects of spaceflight on microbial communities is crucial for the success of long-term, manned space missions. Surface-associated bacterial communities, known as biofilms, were abundant on the Mir space station and continue to be a challenge on the International Space Station. The health and safety hazards linked to the development of biofilms are of particular concern due to the suppression of immune function observed during spaceflight. While planktonic cultures of microbes have indicated that spaceflight can lead to increases in growth and virulence, the effects of spaceflight on biofilm development and physiology remain unclear. To address this issue, Pseudomonas aeruginosa was cultured during two Space Shuttle Atlantis missions: STS-132 and STS-135, and the biofilms formed during spaceflight were characterized. Spaceflight was observed to increase the number of viable cells, biofilm biomass, and thickness relative to normal gravity controls. Moreover, the biofilms formed during spaceflight exhibited a column-and-canopy structure that has not been observed on Earth. The increase in the amount of biofilms and the formation of the novel architecture during spaceflight were observed to be independent of carbon source and phosphate concentrations in the media. However, flagella-driven motility was shown to be essential for the formation of this biofilm architecture during spaceflight. These findings represent the first evidence that spaceflight affects community-level behaviors of bacteria and highlight the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight.

  8. Intermetallic Phase Formation in Explosively Welded Al/Cu Bimetals

    Science.gov (United States)

    Amani, H.; Soltanieh, M.

    2016-08-01

    Diffusion couples of aluminum and copper were fabricated by explosive welding process. The interface evolution caused by annealing at different temperatures and time durations was investigated by means of optical microscopy, scanning electron microscopy equipped with energy dispersive spectroscopy, and x-ray diffraction. Annealing in the temperature range of 573 K to 773 K (300 °C to 500 °C) up to 408 hours showed that four types of intermetallic layers have been formed at the interface, namely Al2Cu, AlCu, Al3Cu4, and Al4Cu9. Moreover, it was observed that iron trace in aluminum caused the formation of Fe-bearing intermetallics in Al, which is near the interface of the Al-Cu intermetallic layers. Finally, the activation energies for the growth of Al2Cu, AlCu + Al3Cu4, Al4Cu9, and the total intermetallic layer were calculated to be about 83.3, 112.8, 121.6, and 109.4 kJ/mol, respectively. Considering common welding methods ( i.e., explosive welding, cold rolling, and friction welding), although there is a great difference in welding mechanism, it is found that the total activation energy is approximately the same.

  9. Signals to promote myelin formation and repair.

    Science.gov (United States)

    Taveggia, Carla; Feltri, Maria Laura; Wrabetz, Lawrence

    2010-05-01

    The myelin sheath wraps large axons in both the CNS and the PNS, and is a key determinant of efficient axonal function and health. Myelin is targeted in a series of diseases, notably multiple sclerosis (MS). In MS, demyelination is associated with progressive axonal damage, which determines the level of patient disability. The few treatments that are available for combating myelin damage in MS and related disorders, which largely comprise anti-inflammatory drugs, only show limited efficacy in subsets of patients. More-effective treatment of myelin disorders will probably be accomplished by early intervention with combinatorial therapies that target inflammation and other processes-for example, signaling pathways that promote remyelination. Indeed, evidence suggests that such pathways might be impaired in pathology and, hence, contribute to the failure of remyelination in such diseases. In this article, we review the molecular basis of signaling pathways that regulate myelination in the CNS and PNS, with a focus on signals that affect differentiation of myelinating glia. We also discuss factors such as extracellular molecules that act as modulators of these pathways. Finally, we consider the few preclinical and clinical trials of agents that augment this signaling.

  10. Effect of intensive melt shearing on the formation of Fe-containing intermetallics in LM24 Al-alloy

    OpenAIRE

    2011-01-01

    Fe is one of the inevitable and detrimental impurities in aluminium alloys that degrade the mechanical performance of castings. In the present work, intensive melt shearing has been demonstrated to modify the morphology of Fe-containing intermetallic compounds by promoting the formation of compact α-Al(Fe,Mn)Si at the expense of needle-shaped β-AlFeSi, leading to an improved mechanical properties of LM24 alloy processed by MC-HPDC process. The promotion of the formation of α -Al(Fe, Mn)Si pha...

  11. Formation of ordered CoAl alloy clusters by the plasma-gas condensation technique

    Science.gov (United States)

    Konno, Toyohiko J.; Yamamuro, Saeki; Sumiyama, Kenji

    2001-09-01

    CoxAl1-x alloy clusters were synthesized from a mixture of Co and Al metal vapors generated by the sputtering of pure metal targets. We observed that the produced alloy clusters were uniform in size, ranging from approximately 20 nm for Al-rich clusters to 10 nm for Co-rich clusters. For a wide average composition range (x≈0.4-0.7), the alloy clusters have the ordered B2 (CsCl-type) structure. In the Co-rich cluster aggregates (x=0.76), the clusters are composed of face-centered-cubic (fcc) Co and minor CoAl(B2) clusters. In the Al-rich aggregates (x=0.23), the clusters are mainly composed of the fcc-Al phase, although clusters occasionally possess a "core-shell structure" with the CoAl(B2) phase surrounded by an Al-rich amorphous phase. These observations are in general agreement with our prediction based on the equilibrium phase diagram. We also noticed that the average composition depends not only on the relative amount of Co and Al vapors, but also on their absolute amount, and even on the Ar gas flow rate, which promotes mixing and cooling the two vapors. These findings show that the formation of alloy clusters in vapor phase is strongly influenced by the kinetics of cluster formation, and is a competing process between the approach to equilibrium and the quenching of the whole system.

  12. Ni/Al2O3 catalysts for syngas methanation: Effect of Mn promoter

    Institute of Scientific and Technical Information of China (English)

    Anmin Zhao; Weiyong Ying; Haitao Zhang; Hongfang Ma; Dingye Fang

    2012-01-01

    Ni/Al2O3 catalysts with different amounts of manganese ranging from 1 to 3 wt% as promoter were prepared by co-impregnation method.The catalysts were characterized by N2 physisorption,XRD,TPR,SEM and TEM.Their catalytic activity towards syngas methanation reaction was also investigated using a fixed-bed integral reactor.It was demonstrated that the addition of manganese to Ni/Al2O3 catalysts can increase the catalyst surface area and average pore volume,but decrease NiO crystallite size,leading to higher activity and stability.The effects of reaction temperature,pressure and weight hourly space velocity (WHSV) on carbon oxides conversion and CH4 formation rate were also studied.High carbon oxides conversion,CH4 selectivity and formation rate were achieved at the reaction temperature range of 280-300 ℃.

  13. A study on the formation of iron aluminide (FeAl) from elemental powders

    Energy Technology Data Exchange (ETDEWEB)

    Sina, H.; Corneliusson, J.; Turba, K.; Iyengar, S.

    2015-07-05

    Highlights: • Fe–40 at.% Al discs with coarse iron powder showed precombustion and combustion peaks. • Loose powder mixtures and discs with fine iron powder showed only combustion peaks. • Slower heating rate and fine aluminum particles promote precombustion. • The major product formed during both the reactions was Fe{sub 2}Al{sub 5}. • Heating the samples to 1000 °C yielded a stable FeAl phase as the final product. - Abstract: The formation of iron aluminide (FeAl) during the heating of Fe–40 at.% Al powder mixture has been studied using a differential scanning calorimeter. The effect of particle size of the reactants, compaction of the powder mixtures as well as the heating rate on combustion behavior has been investigated. On heating compacted discs containing relatively coarser iron powder, DSC data show two consecutive exothermic peaks corresponding to precombustion and combustion reactions. The product formed during both these reactions is Fe{sub 2}Al{sub 5} and there is a volume expansion in the sample. The precombustion reaction could be improved by a slower heating rate as well as a better surface coverage of iron particles using relatively finer aluminum powder. The combustion reaction was observed to be weaker after a strong precombustion stage. Heating the samples to 1000 °C resulted in the formation of a single and stable FeAl phase through the diffusional reaction between Fe{sub 2}Al{sub 5} and residual iron. DSC results for compacted discs containing relatively finer iron powder and for the non-compacted samples showed a single combustion exotherm during heating, with Fe{sub 2}Al{sub 5} as the product and traces of FeAl. X-ray diffraction and EDS data confirmed the formation of FeAl as the final product after heating these samples to 1000 °C.

  14. Glycerol metabolism promotes biofilm formation by Pseudomonas aeruginosa.

    Science.gov (United States)

    Scoffield, Jessica; Silo-Suh, Laura

    2016-08-01

    Pseudomonas aeruginosa causes persistent infections in the airways of cystic fibrosis (CF) patients. Airway sputum contains various host-derived nutrients that can be utilized by P. aeruginosa, including phosphotidylcholine, a major component of host cell membranes. Phosphotidylcholine can be degraded by P. aeruginosa to glycerol and fatty acids to increase the availability of glycerol in the CF lung. In this study, we explored the role that glycerol metabolism plays in biofilm formation by P. aeruginosa. We report that glycerol metabolism promotes biofilm formation by both a chronic CF isolate (FRD1) and a wound isolate (PAO1) of P. aeruginosa. Moreover, loss of the GlpR regulator, which represses the expression of genes involved in glycerol metabolism, enhances biofilm formation in FRD1 through the upregulation of Pel polysaccharide. Taken together, our results suggest that glycerol metabolism may be a key factor that contributes to P. aeruginosa persistence by promoting biofilm formation.

  15. ALS1 and ALS3 gene expression and biofilm formation in Candida albicans isolated from vulvovaginal candidiasis

    Directory of Open Access Journals (Sweden)

    Shahla Roudbarmohammadi

    2016-01-01

    Conclusion: The results attained indicated that there is an association between the expression of ALS1 and ALS3 genes and fluconazole resistance in C. albicans. A considerable percent of the isolates expressing the ALS1 and ALS3 genes may have contributed to their adherence to vagina and biofilm formation.

  16. P-selectin promotes neutrophil extracellular trap formation in mice.

    Science.gov (United States)

    Etulain, Julia; Martinod, Kimberly; Wong, Siu Ling; Cifuni, Stephen M; Schattner, Mirta; Wagner, Denisa D

    2015-07-01

    Neutrophil extracellular traps (NETs) can be released in the vasculature. In addition to trapping microbes, they promote inflammatory and thrombotic diseases. Considering that P-selectin induces prothrombotic and proinflammatory signaling, we studied the role of this selectin in NET formation. NET formation (NETosis) was induced by thrombin-activated platelets rosetting with neutrophils and was inhibited by anti-P-selectin aptamer or anti-P-selectin glycoprotein ligand-1 (PSGL-1) inhibitory antibody but was not induced by platelets from P-selectin(-/-) mice. Moreover, NETosis was also promoted by P-selectin-immunoglobulin fusion protein but not by control immunoglobulin. We isolated neutrophils from mice engineered to overproduce soluble P-selectin (P-selectin(ΔCT/ΔCT) mice). Although the levels of circulating DNA and nucleosomes (indicative of spontaneous NETosis) were normal in these mice, basal neutrophil histone citrullination and presence of P-selectin on circulating neutrophils were elevated. NET formation after stimulation with platelet activating factor, ionomycin, or phorbol 12-myristate 13-acetate was significantly enhanced, indicating that the P-selectin(ΔCT/ΔCT) neutrophils were primed for NETosis. In summary, P-selectin, cellular or soluble, through binding to PSGL-1, promotes NETosis, suggesting that this pathway is a potential therapeutic target for NET-related diseases.

  17. Kinetics of formation of Al nanocrystals from amorphous Al-Sm alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rizzi, P. [Torino Univ. (Italy). Dipt. di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali; Baricco, M. [Torino Univ. (Italy). Dipt. di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali; Battezzati, L. [Torino Univ. (Italy). Dipt. di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali; Schumacher, P. [Cambridge Univ. (United Kingdom). Dept. of Metallurgy and Materials Science; Greer, A.L. [Cambridge Univ. (United Kingdom). Dept. of Metallurgy and Materials Science

    1997-06-01

    This paper presents results on the formation of nanocrystals in Al{sub 92}Sm{sub 8} amorphous ribbons produced by melt-spinning. Their crystallization behaviour was examined by means of DSC, XRD and TEM. DSC scans at 40 K/min show that a primary crystallization of {alpha}-Al nanocrystals occurs at about 453 K. Isothermal analysis are performed at the temperature of 444 K for various annealing times in order to obtain information on the transformed fraction, the nucleation frequency and the growth rate. From TEM observations the mean crystal size and the density of crystals are determined. It is found that the nucleation rate is considerable during the first minutes of annealing and then decreases steadily. Growth is also fast at the beginning of annealing and then is very sluggish. (orig.)

  18. The promotional effects of cesium promoter on higher alcohol synthesis from syngas over cesium-promoted Cu/ZnO/Al2O3 catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jie; Cai, Qiuxia; Wan, Yan; Wan, Shaolong; Wang, Li; Lin, Jingdong; Mei, Donghai; Wang, Yong

    2016-09-02

    In this study, the promotional effects of cesium promoter on higher alcohol (C2+OH) synthesis from syngas over Cs-Cu/ZnO/Al2O3 catalysts were investigated using a combined experimental and theoretical density functional theory (DFT) calculation method. In the presence of cesium, the C2+OH productivity increases from 77.1 g•kgcat-1•h-1 to 157.3 g•kgcat-1•h-1 at 583 K due to the enhancement of the initial C–C bond formation. Detailed analysis of chain growth probabilities (CGPs) confirms that initial C–C bond formation is the rate-determining step in the temperature range of 543-583 K. Addition of cesium promoter significantly increases the productivities of 2-methyl-1-propanol, while the CGPs values (C3* to 2-methyl-C3*) is almost unaffected. With the assistance of cesium promoter, the CGPs of the initial C–C bond formation step (C1* to C2*) could be increased from 0.13 to 0.25 at 583 K. DFT calculations indicate that the initial C–C bond formation is mainly contributed by the HCO+HCO coupling reaction over the ZnCu(211) model surface. In the presence of the Cs2O, the stabilities of key reaction intermediates such as HCO and H2CO are enhanced which facilitates both HCO+HCO and HCO+H2CO coupling reaction steps with lower activation barriers over the Cs2O-ZnCu(211) surface. The promotional effects of cesium on the C2+OH productivity are also benefited from the competitive CH+HCO coupling reaction over CH hydrogenation that leads to lower alkane formation. In addition, Bader charge analysis suggests that the presence of cesium ions would facilitate the nucleophilic reaction between HCO and H2CO for initial C–C bond formation. This work was supported by the National Natural Science Foundation of China (No. 91545114 and No. 91545203). We appreciate the joint PhD scholarship support from the China Scholarship Council. The authors would also like to thank the support from Collaborative Innovation Center of Chemistry for Energy Materials (2011-iChEM). DM

  19. Multi-protein delivery by nanodiamonds promotes bone formation.

    Science.gov (United States)

    Moore, L; Gatica, M; Kim, H; Osawa, E; Ho, D

    2013-11-01

    Bone morphogenetic proteins (BMPs) are well-studied regulators of cartilage and bone development that have been Food and Drug Administration (FDA)-approved for the promotion of bone formation in certain procedures. BMPs are seeing more use in oral and maxillofacial surgeries because of recent FDA approval of InFUSE(®) for sinus augmentation and localized alveolar ridge augmentation. However, the utility of BMPs in medical and dental applications is limited by the delivery method. Currently, BMPs are delivered to the surgical site by the implantation of bulky collagen sponges. Here we evaluate the potential of detonation nanodiamonds (NDs) as a delivery vehicle for BMP-2 and basic fibroblast growth factor (bFGF). Nanodiamonds are biocompatible, 4- to 5-nm carbon nanoparticles that have previously been used to deliver a wide variety of molecules, including proteins and peptides. We find that both BMP-2 and bFGF are readily loaded onto NDs by physisorption, forming a stable colloidal solution, and are triggered to release in slightly acidic conditions. Simultaneous delivery of BMP-2 and bFGF by ND induces differentiation and proliferation in osteoblast progenitor cells. Overall, we find that NDs provide an effective injectable alternative for the delivery of BMP-2 and bFGF to promote bone formation.

  20. Hydrostatic Pressure Promotes Domain Formation in Model Lipid Raft Membranes.

    Science.gov (United States)

    Worcester, David L; Weinrich, Michael

    2015-11-01

    Neutron diffraction measurements demonstrate that hydrostatic pressure promotes liquid-ordered (Lo) domain formation in lipid membranes prepared as both oriented multilayers and unilamellar vesicles made of a canonical ternary lipid mixture for which demixing transitions have been extensively studied. The results demonstrate an unusually large dependence of the mixing transition on hydrostatic pressure. Additionally, data at 28 °C show that the magnitude of increase in Lo caused by 10 MPa pressure is much the same as the decrease in Lo produced by twice minimum alveolar concentrations (MAC) of general anesthetics such as halothane, nitrous oxide, and xenon. Therefore, the results may provide a plausible explanation for the reversal of general anesthesia by hydrostatic pressure.

  1. Intracystic negative pressure may promote bone formation around jaw cysts

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi; HAN Qi-bing; LIU Bing

    2011-01-01

    The growth and enlargement of jaw cysts are associated with raised intracystic pressure and bone resorption surrounding the cysts. The major bone-resorbing cells are the osteoclasts. They are acting under the influence of local bone-resorbing factors: prostaglandins, proteinases and cytokines. It was found that positive pressure enhanced the expression of IL-1αmRNA and protein in epithelial cells of odontogenic keratocyst, and increased the secretion of matrix metalloproteinase and PGE in a co-culture of odontogenic keratocyst fibroblasts and epithelial cells. However, the signal intensities for IL-1α mRNA and protein in the epithelium were significantly decreased after marsupialization which relived intracystic pressure. Experimental study indicated that intermittent negative pressure could promote osteogenesis in human bone marrow-derived stroma cells (BMSCs) in vitro. We propose a hypothesis that bone formation around the cyst of the jaws would be stimulated by intracystic negative pressure.

  2. Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kalay, Yunus Eren [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T0 curves, which makes Al-Si a good candidate for solubility extension while the plunging T0 line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of ~0.2, JH and TMK deviate from

  3. Glass Formation in Ni-Zr-(Al Alloy Systems

    Directory of Open Access Journals (Sweden)

    Lanping Huang

    2013-01-01

    Full Text Available Structural and thermal properties of binary Ni100-xZrx (30formation of the equilibrium crystalline phases with a high growth rate are responsible for their low glass-forming abilities (GFAs. Relatively low thermal conductivities of Ni-based alloys are also considered to be another factor to limit their GFAs. The GFA of the binary Ni65.5Zr34.5 alloy alloyed with 4% or 5% Al was enhanced, and a fully glassy rod with a diameter of 0.5 mm was formed.

  4. Effects of Ti, Al and Hf on niobium silcides formation in the Nb-Si in situ composites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The effects of alloying elements Ti, Al and Hf on niobium silicides formation in the Nb-Si in situ composites have been investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The binary, ternary and multicomponent alloys have been fabricated by vacuum non-consumable arc melting method. The results show that Ti tends to stabilize Nb3Si phase, while Al promotes the direct formation of β-Nb5Si3 phase with a tetrahedral D8m structure. Exceptionally, it seems that Hf is beneficial to the formation of γ-Nb5Si3 phase with a hexangular D88 structure. For the multicomponent Nb-Si in situ composites, the cooperative effects of different elements on niobium silicides formation basically maintain the character of ternary system.

  5. Vibration acceleration promotes bone formation in rodent models

    Science.gov (United States)

    Uchida, Ryohei; Nakata, Ken; Kawano, Fuminori; Yonetani, Yasukazu; Ogasawara, Issei; Nakai, Naoya; Mae, Tatsuo; Matsuo, Tomohiko; Tachibana, Yuta; Yokoi, Hiroyuki; Yoshikawa, Hideki

    2017-01-01

    centrifuge acceleration group had no significant difference compared those in control-CA group. Union rate and BV in the low-magnitude group of RFH model were also significantly higher than those in the other groups (Union rate: 60% v.s. 0% in the high-magnitude group and 10% in the control-VA group, BV: 0.69±0.30mm3 v.s. 0.15±0.09mm3 in high-magnitude group and 0.22±0.17mm3 in control-VA group). BV/TV in the low-magnitude group of RFH model was significantly higher than that in control-VA group (59.4±14.9% v.s. 35.8±13.5%). On the other hand, radiographic union rate (10% in centrifuge acceleration group v.s. 20% in control-CA group) and micro-CT parameters in RFH model were not significantly different between two groups in the constant acceleration studies. Radiographic images of non-union rib fractures showed cartilage at the fracture site and poor new bone formation, whereas union samples showed only new bone. In conclusion, low-magnitude vibration acceleration promoted bone formation at the trunk in both BMP-induced ectopic bone formation and rib fracture healing models. However, the micro-CT parameters were not similar between two models, which suggested that there might be difference in the mechanism of effect by vibration between two models. PMID:28264058

  6. MODELING OF 'BANDING' MICROSTRUCTURE FORMATION IN CENTRIFUGALLY SOLIDIFIED Ti-6Al-4V ALLOY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Numerical investigations of the 'banding' microstructure formation during solidifica-tion of Ti-6Al-4V alloy in the centrifugal casting are conducted using a multi-scale model, which combines the finite difference method (FDM) at the macroscale with a cellular automaton (CA) model at the microscale. The macro model is used to simu-late the fluid flow and heat transfer throughout the casting. The micro model is used to predict the nucleation and growth of microstructures. With the proposed model,numerical simulations are performed to study the influences of the nucleation density,mould rotation speed, and casting size upon the 'banding' microstructure formation. It is noted that changing the nucleation density has a minor effect on the microstructure formation. The rotation speed promotes the formation of 'banding' microstructure,which is more noticeable for larger size castings. The major mechanism responsi-ble for this 'banding' phenomenon is the spatial variation in cooling rates created by centrifugal force.

  7. Enthalpies of formation of compounds in Al-Ni-Y system

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The enthalpies of formation of the ternary compounds Al4NiY, Al2NiY, Al2Ni6Y3, Al16 Ni3Y, AlNiY, Al3Ni2Y, AlNi8Y3, Al7Ni3Y2, and of the binary comp ounds Al2Y containing nickel and Ni5Y containing aluminum have been determined by high temperature reaction calorimetry. The enthalpy values measured are compared to previously published results where available as well as extended Miedema model predictions. The melting points of the compounds were determined by DTA and X-ray diffraction was used to confirm the crystal structures of the compounds. The enthalpi es of formation of the ternary compounds show a maximum along the 50%Al (mole fr action) section. The ternary compounds appear along lines of constant yttrium content consistent with binary compound solubility extensions.

  8. Tacrolimus reduces scar formation and promotes sciatic nerve regeneration

    Institute of Scientific and Technical Information of China (English)

    Jun Que; Quan Cao; Tao Sui; Shihao Du; Ailiang Zhang; Dechao Kong; Xiaojian Cao

    2012-01-01

    A sciatic nerve transection and repair model was established in Sprague-Dawley rats by transecting the tendon of obturator internus muscle in the greater sciatic foramen and suturing with nylon sutures. The models were treated with tacrolimus gavage (4 mg/kg per day) for 0, 2, 4 and 6 weeks. Specimens were harvested at 6 weeks of intragastric administration. Masson staining revealed that the collagen fiber content and scar area in the nerve anastomosis of the sciatic nerve injury rats were significantly reduced after tacrolimus administration. Hematoxylin-eosin staining showed that tacrolimus significantly increased myelinated nerve fiber density, average axon diameter and myelin sheath thickness. Intragastric administration of tacrolimus also led to a significant increase in the recovery rate of gastrocnemius muscle wet weight and the sciatic functional index after sciatic nerve injury. The above indices were most significantly improved at 6 weeks after of tacrolimus gavage. The myelinated nerve fiber density in the nerve anastomosis and the sciatic nerve functions had a significant negative correlation with the scar area, as detected by Spearman’s rank correlation analysis. These findings indicate that tacrolimus can promote peripheral nerve regeneration and accelerate the recovery of neurological function through the reduction of scar formation.

  9. The formation of intermetallic compounds during interdiffusion of Mg–Al/Mg–Ce diffusion couples

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jiahong [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Jiang, Bin, E-mail: jiangbinrong@cqu.edu.cn [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Li, Xin [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Yang, Qingshan [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Dong, Hanwu [Chongqing Academy of Science and Technology, Chongqing 401123 (China); Xia, Xiangsheng [No. 59 Institute of China Ordnance Industry, Chongqing 400039 (China); Pan, Fusheng [College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China)

    2015-01-15

    Graphical abstract: Al–Ce intermetallic compounds (IMCs) formed in Mg–Al/Mg–Ce diffusion couples. During the whole diffusion process, Al was the dominant diffusing species, and it substituted for Mg atoms of the Mg–Ce substrate. Five Al–Ce IMCs of Al{sub 4}Ce, Al{sub 11}Ce{sub 3}, Al{sub 3}Ce, Al{sub 2}Ce, and AlCe were formed via the reaction of Al and Ce. - Highlights: • Al–Ce IMCs formation in the Mg–Al/Mg–Ce diffusion couples was studied. • Formation of Al{sub 4}Ce as the first phase was rationalized using the Gibbs free energy. • The activation energy for the growth of the diffusion reaction zones was 36.6 kJ/mol. - Abstract: The formation of Al–Ce intermetallic compounds (IMCs) during interdiffusion of Mg–Al/Mg–Ce diffusion couples prepared by solid–liquid contact method was investigated at 623 K, 648 K and 673 K for 24 h, 48 h and 72 h, respectively. During the whole diffusion process, Al was the dominant diffusing species, and it substituted for Mg of the Mg–Ce substrate. Five Al–Ce IMCs of Al{sub 4}Ce, Al{sub 11}Ce{sub 3}, Al{sub 3}Ce, Al{sub 2}Ce and AlCe were formed via the reaction of Al and Ce. The formation of Al{sub 4}Ce as the first kind of IMC was rationalized on the basis of an effective Gibbs free energy model. The activation energy for the growth of the total diffusion reaction layer was 36.6 kJ/mol.

  10. Effects of MgO promoter on properties of Ni/Al2O3 catalysts for partial oxidation of methane to syngas

    Institute of Scientific and Technical Information of China (English)

    QIU Yejun; CHEN Jixiang; ZHANG Jiyan

    2007-01-01

    The effects of MgO promoter on the physicochemical properties and catalytic performance of Ni/Al2O3 catalysts for the partial oxidation of methane to syngas were studied by means of BET,XRD,H2-TPR,TEM and performance evaluation.It was found that the MgO promoter benefited from the uniformity of nickel species in the catalysts,inhibited the formation of NiAl2O4 spinel and improved the interaction between nickel species and support.These results were related to the formation of NiO-MgO solid solution and MgAl2O4 spinel.Moreover,for the catalysts with a proper amount of MgO promoter,the nickel dispersiveness was enhanced,therefore making their catalytic performance in methane partial oxidation improved.However,the excessive MgO promoter exerted a negative effect on the catalytic performance.Meanwhile,the basicity of MgO promoted the reversed water-gas shift reaction,which led to an increase in CO selectivity and a decrease in H2 selectivity.The suitable content of MgO promoter in Ni/Al2O3 catalyst was~7 wt-%.

  11. Alpha-Toxin Promotes Mucosal Biofilm Formation by Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Michele J Anderson

    2012-05-01

    Full Text Available Staphylococcus aureus causes numerous diseases in humans ranging from the mild skin infections to serious, life-threatening, superantigen-mediated Toxic Shock Syndrome (TSS. S. aureus may also be asymptomatically carried in the anterior nares, vagina or on the skin, which serve as reservoirs for infection. Pulsed-field gel electrophoresis clonal type USA200 is the most widely disseminated colonizer and a major cause of TSS. Our prior studies indicated that α-toxin was a major epithelial proinflammatory exotoxin produced by TSS S. aureus USA200 isolates. It also facilitated the penetration of TSS Toxin-1 (TSST-1 across vaginal mucosa. However, the majority of menstrual TSS isolates produce low α-toxin due to a nonsense point mutation at codon 113, designated hly, suggesting mucosal adaptation. The aim of this study was to characterize the differences between TSS USA200 strains [high (hla+ and low (hly+ α-toxin producers] in their abilities to infect and disrupt vaginal mucosal tissue. A mucosal model was developed using ex vivo porcine vaginal mucosa, LIVE/DEAD® staining and confocal microscropy to characterize biofilm formation and tissue viability of TSS USA 200 isolates CDC587 and MN8, which contain the α-toxin pseudogene (hly, MNPE (hla+ and MNPE isogenic hla knockout (hlaKO. All TSS strains grew to similar bacterial densities (1-5 x 108 CFU on the mucosa and were proinflammatory over 3 days. However, MNPE formed biofilms with significant reductions in the mucosal viability whereas neither CDC587, MN8 (hly+, or MNPE hlaKO, formed biofilms and were less cytotoxic. The addition of exogenous, purified α-toxin to MNPE hlaKO restored the biofilm phenotype. Our studies suggest α-toxin affects S. aureus phenotypic growth on vaginal mucosa, by promoting tissue disruption and biofilm formation; and α–toxin mutants (hly are not benign colonizers, but rather form a different type of infection, which we have termed high density pathogenic

  12. DEK over-expression promotes mitotic defects and micronucleus formation.

    Science.gov (United States)

    Matrka, Marie C; Hennigan, Robert F; Kappes, Ferdinand; DeLay, Monica L; Lambert, Paul F; Aronow, Bruce J; Wells, Susanne I

    2015-01-01

    The DEK gene encodes a nuclear protein that binds chromatin and is involved in various fundamental nuclear processes including transcription, RNA splicing, DNA replication and DNA repair. Several cancer types characteristically over-express DEK at the earliest stages of transformation. In order to explore relevant mechanisms whereby DEK supports oncogenicity, we utilized cancer databases to identify gene transcripts whose expression patterns are tightly correlated with that of DEK. We identified an enrichment of genes involved in mitosis and thus investigated the regulation and possible function of DEK in cell division. Immunofluorescence analyses revealed that DEK dissociates from DNA in early prophase and re-associates with DNA during telophase in human keratinocytes. Mitotic cell populations displayed a sharp reduction in DEK protein levels compared to the corresponding interphase population, suggesting DEK may be degraded or otherwise removed from the cell prior to mitosis. Interestingly, DEK overexpression stimulated its own aberrant association with chromatin throughout mitosis. Furthermore, DEK co-localized with anaphase bridges, chromosome fragments, and micronuclei, suggesting a specific association with mitotically defective chromosomes. We found that DEK over-expression in both non-transformed and transformed cells is sufficient to stimulate micronucleus formation. These data support a model wherein normal chromosomal clearance of DEK is required for maintenance of high fidelity cell division and chromosomal integrity. Therefore, the overexpression of DEK and its incomplete removal from mitotic chromosomes promotes genomic instability through the generation of genetically abnormal daughter cells. Consequently, DEK over-expression may be involved in the initial steps of developing oncogenic mutations in cells leading to cancer initiation.

  13. Preparation of Nb3Al superconductor by powder metallurgy and effect of mechanical alloying on the phase formation

    Institute of Scientific and Technical Information of China (English)

    Zhao Liu; Yongliang Chen; Lupeng Du; Pingyuan Li; Yajing Cui; Xifeng Pan; Guo Yan

    2014-01-01

    Adoption of powder-in-tube method to fabri-cate superconducting wire can realize a large application of Nb3Al prepared by powder metallurgy. Powder metallurgy was used to synthesize Nb3Al under various heat-treatment conditions, annealing temperature was varied from 700 to 1,000 ?C and heating time was varied from 10 to 50 h. X-ray diffraction patterns reveal that a reaction between Nb and Al took place and formed NbAl3 phase. Under current heat-treatment conditions (annealing temperature was varied from 700 to 1,000 ?C and heating time was varied from 10 to 50 h), NbAl3 was so stable that it did not further react with the unreacted Nb and was not sensitive to the heat-treatment condition. By mechanical alloying, adoption of high-energy ball milling significantly decreases particle size and enhances surface free energy, which promotes the formation of Nb3Al phase. X-ray diffraction patterns indicate that relatively pure Nb3Al phase was obtained under the same heat-treatment condition. Energy-disper-sive X-ray analysis measurement demonstrates that the obtained samples were close to the right stoichiometry of A15 structure Nb3Al.

  14. Formation Mechanism and Emission Spectrum of AlO Radicals in Reaction of Laser-ablated Al Atom and Oxygen

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-dong; LI Hai-Yang

    2003-01-01

    The emission spectrum of AlO radicals was analyzed in 440-540 nm in the reaction of laser ablated Al beam and O2. The carrier of spectrum was assigned to Δν=0, ±1, ±2 vibrational sequences of B2Σ+-X2Σ+ transition of AlO radicals, the observed maximum vibrational quantum number was ν′=6. The rotational and vibrational temperatures of B state were estimated at 3000 and 7500 K by spectrally simulating the rovibronic population distribution. There is a strong evidence that the production of excited Al(2S) atoms is essential to the formation of excited AlO radicals.

  15. Al-2 of Aggregatibacter actinomycetemcomitans inhibits Candida albicans biofilm formation

    NARCIS (Netherlands)

    Bachtiar, Endang W.; Bachtiar, Boy M.; Jarosz, Lucja M.; Amir, Lisa R.; Sunarto, Hari; Ganin, Hadas; Meijler, Michael M.; Krom, Bastiaan P.

    2014-01-01

    Aggregatibacter actinomycetemcomitans, a Gram-negative bacterium, and Candida albicans, a polymorphic fungus, are both commensals of the oral cavity but both are opportunistic pathogens that can cause oral diseases. A. actinomycetemcomitans produces a quorum-sensing molecule called autoinducer-2 (Al

  16. Formation and stability of Al-Nd and Al-Nd-Fe metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Battezzati, Livio (Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Universita di Torino, Via Pietro Giuria 9, 10125 Turin (Italy)); Baricco, Marcello (Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Universita di Torino, Via Pietro Giuria 9, 10125 Turin (Italy)); Antonione, Carlo (Dipartimento di Chimica Inorganica, Chimica Fisica e Chimica dei Materiali, Universita di Torino, Via Pietro Giuria 9, 10125 Turin (Italy))

    1994-07-01

    Partially amorphous Al[sub 91]Nd[sub 9] and Al[sub 86]Nd[sub 9]Fe[sub 5] ribbons were prepared by melt spinning. Metastable crystalline phases were found in both alloys. Complete amorphization of Al[sub 86]Nd[sub 9]Fe[sub 5] was also achieved. Crystallization was monitored by differential scanning calorimetry (DSC). It occurs in two stages at 440 and 510 K for Al[sub 91]Nd[sub 9]. Al[sub 86]Nd[sub 9]Fe[sub 5] presented a eutectic crystallization at 550 K. Microscopy observations, combined with Johnson-Mehl-Avrami (JMA) analyses performed in isothermal DSC traces, showed that Al[sub 91]Nd[sub 9] transforms via growth on pre-existing crystals. Al[sub 86]Nd[sub 9]Fe[sub 5] transformed via heterogeneous nucleation on sites unevenly distributed through the ribbon. The fitting of isothermal peaks by means of the JMA equation was less satisfactory. The limits of this approach are discussed. ((orig.))

  17. Electrochemical Formation of Al-Li Alloys by Codeposition of Al and Li from LiCl-KCl-AlF3 Melts at 853 K

    Institute of Scientific and Technical Information of China (English)

    SUN Yi; ZHANG Mi-lin; HAN Wei; LI Mei; YANG Yu-sheng

    2013-01-01

    The electrochemical behavior of Al(Ⅲ) ions was studied in molten LiCl-KCl melts on a molybdenum electrode.Cyclic voltammetry,chronopotentiometry and chronoamperometry were used to explore the deposition mechanism of Al and Li.Cyclic voltammetry expriment indicates that under potential deposition(UPD) of lithium on pre-deposited aluminium led to the formation of liquid Al-Li alloys at 853 K.The diffusion coefficient of Al(Ⅲ) ions at 853 K in LiCl-KCl-AlF3(1%,mass fraction) melts was determined to be (2.79±0.05)× 10-5 cm2/s.Chronopotentiograms and chronoamperograms demonstrate that the codeposition of Al(Ⅲ) and Li(Ⅰ) ions formed Al-Li alloys at cathodic current densities higher than-0.28 A/cm2 or cathodic potentials more negative than-2.20 V.X-Ray diffraction(XRD) pattern indicates that Al-Li alloys with different phases formed via galvanostatic electrolysis.Inductively coupled plasma(ICP) analyses of the samples obtained by electrolysis show that lithium and aluminium contents of Al-Li alloys could be controlled by AlF3 concentration and current intensity.

  18. Induced dicentric chromosome formation promotes genomic rearrangements and tumorigenesis

    OpenAIRE

    Gascoigne, Karen E; Cheeseman, Iain M.

    2013-01-01

    Chromosomal rearrangements can radically alter gene products and their function, driving tumor formation or progression. However, the molecular origins and evolution of such rearrangements are varied and poorly understood, with cancer cells often containing multiple, complex rearrangements. One mechanism that can lead to genomic rearrangements is the formation of a “dicentric” chromosome containing two functional centromeres. Indeed, such dicentric chromosomes have been observed in cancer cel...

  19. Formation and growth model of B-Al permeation layer of Steel 45

    Institute of Scientific and Technical Information of China (English)

    吉泽升; 李庆芬; 李冬华

    2002-01-01

    The B-Al permeation layers of Steel 45 were studied by means of SEM, TEM and XRD. The formation and growth model of permeation layer was proposed. The layer formation, growth and the migration behaviors of B were discussed. It is suggested that the diffusion of Al is deferred when the surface was covered by borides and aluminize compounds are surrounded by borides with the further growing of borides.

  20. Effects of Selected Promoters on Ni/γ-Al2O3 Catalyst Performance in Methane Dry Reforming%Effects of Selected Promoters on Ni/γ-Al2O3Catalyst Performance in Methane Dry Reforming

    Institute of Scientific and Technical Information of China (English)

    Ahmed S. A.AL-FATESH; Anis H. FAKEEHA; Ahmed E. ABASAEED

    2011-01-01

    The Ni catalysts supported on γ-Al2O3 were synthesized by an impregnation method.Their catalytic performance in methane dry reforming was investigated.The reforming reactions were carried out in a mieroreactor using a CO2∶CH4 feed ratio of 1∶1,a F/W =2640ml/(h·g),reaction temperatures between 500-850 ℃,and at atmospheric pressure.The influence of Ca,Ce,and Zr promoters on catalyst stability,coke deposition,and the H2/CO ratio were also studied.Effluents were analyzed using an online gas chromatograph equipped with a thermal conductivity detector.The spent and fresh catalysts were characterized by scanning electron microscopy and thermogravimetric analysis.It was found that 3%Ni/γ-Al2O3 promoted with 0.15% Ce and 0.05% Ca gave the best performance and resulted in less coke formation.The highest CH4 and CO2 conversion activities were found to be 94.1% and 98.3% at 850 ℃,respectively.Stability tests were carried out for 130 h and this provided a H2 yield of 91%.Moreover,the amount of formed carbon was negligible and did not increase to more than 1.5 wt%.

  1. Carbon and oxygen isotope variations of the Middle-Late Triassic Al Aziziyah Formation, northwest Libya

    Science.gov (United States)

    Moustafa, Mohamed S. H.; Pope, Michael C.; Grossman, Ethan L.; Mriheel, Ibrahim Y.

    2016-06-01

    This study presents the δ13C and δ18O records from whole rock samples of the Middle-Late Triassic (Ladinian-Carnian) Al Aziziyah Formation that were deposited on a gently sloping carbonate ramp within the Jifarah Basin of Northwest Libya. The Al Aziziyah Formation consists of gray limestone, dolomite, and dolomitic limestone interbedded with shale. The Ghryan Dome and Kaf Bates sections were sampled and analyzed for carbon and oxygen isotope chemostratigraphy to integrate high-resolution carbon isotope data with an outcrop-based stratigraphy, to provide better age control of the Al Aziziyah Formation. This study also discusses the relation between the facies architecture of the Al Aziziyah Formation and the carbon isotope values. Seven stages of relative sea level rise and fall within the Ghryan Dome were identified based on facies stacking patterns, field observations and carbon stable isotopes. The Al Aziziyah Formation δ13C chemostratigraphic curve can be partially correlated with the Triassic global δ13C curve. This correlation indicates that the Al Aziziyah Formation was deposited during the Ladinian and early Carnian. No straight-forward relationship is seen between δ13C and relative sea level probably because local influences complicated systematic environmental and diagenetic isotopic effects associated with sea level change.

  2. Oxylipins produced by Pseudomonas aeruginosa promote biofilm formation and virulence

    Science.gov (United States)

    Martínez, Eriel; Campos-Gómez, Javier

    2016-01-01

    The oxygenation of unsaturated fatty acids by dioxygenases occurs in all kingdoms of life and produces physiologically important lipids called oxylipins. The biological roles of oxylipins have been extensively studied in animals, plants, algae and fungi, but remain largely unidentified in prokaryotes. The bacterium Pseudomonas aeruginosa displays a diol synthase activity that transforms several monounsaturated fatty acids into mono- and di-hydroxylated derivatives. Here we show that oxylipins derived from this activity inhibit flagellum-driven motility and upregulate type IV pilus-dependent twitching motility of P. aeruginosa. Consequently, these oxylipins promote bacterial organization in microcolonies, increasing the ability of P. aeruginosa to form biofilms in vitro and in vivo (in Drosophila flies). We also demonstrate that oxylipins produced by P. aeruginosa promote virulence in Drosophila flies and lettuce. Our study thus uncovers a role for prokaryotic oxylipins in the physiology and pathogenicity of bacteria. PMID:27929111

  3. Autoreduction of promoted Ni/γ-Al 2O 3 during autothermal reforming of methane

    Science.gov (United States)

    Dias, Joelmir Augusto Costa; Assaf, José Mansur

    The addition of the noble metals Pt, Pd and Ir to the Ni/γ-Al 2O 3 catalyst used in the autothermal reforming of methane was investigated, with the aim of making the reaction ignite without previous reduction of the catalyst with H 2. In TPR-CH 4, the catalysts promoted with Pt and Ir chloride suffered reduction at temperatures lower than 500 °C, while the unpromoted catalyst and those promoted by addition of PdCl 2 did not suffer reduction. Pd promoted the reduction only when added as the nitrate. The catalytic tests of intermittent start-up, alternating with air flow, showed results consistent with those from the TPR-CH 4. Pt- and Ir-promoted catalysts were active in all the start-ups, producing a great quantity of hydrogen, while the sample promoted via paladium chloride did not produce hydrogen in significant quantity, converting methane only to CO 2 and water. The samples promoted via palladium nitrate were very active in autothermal reforming without previous reduction, producing a great quantity of hydrogen.

  4. Lipid Oxidation Promotes Acrylamide Formation in Fat-Rich Systems

    NARCIS (Netherlands)

    Capuano, Edoardo

    2016-01-01

    Evidence from model systems suggests that lipid oxidation can contribute to acrylamide (AA) formation through the generation of secondary lipid oxidation carbonyl products, mainly aldehydes, which are able to degrade asparagine to AA. In this respect, factors affecting the extent of lipid oxidati

  5. The stratigraphic positions of the Wadi Dukhan and Al Uwayliah formations, northeast Libya – a review

    NARCIS (Netherlands)

    Tmalla, A.F.A.

    2007-01-01

    The stratigraphic positions of the Wadi Dukhan and Al Uwayliah formations are reviewed. Diagnostic Maastrichtian larger foraminiferal species from the Wadi Dukhan Formation in well B7 – 41 (Cyrenaica) and in well U2 – 6 (northeastern Sirt Basin) are illustrated for the first time. These species are

  6. Chemical structure of vanadium-based contact formation on n-AlN

    Energy Technology Data Exchange (ETDEWEB)

    Pookpanratana, S.; France, R.; Blum, M.; Bell, A.; Bar, M.; Weinhardt, L.; Zhang, Y.; Hofmann, T.; Fuchs, O.; Yang, W.; Denlinger, J. D.; Mulcahy, S.; Moustakas, T. D.; Heske, Clemens

    2010-05-17

    We have investigated the chemical interaction between a Au/V/Al/V layer structure and n-type AlN epilayers using soft x-ray photoemission, x-ray emission spectroscopy, and atomic force microscopy. To understand the complex processes involved in this multicomponent system, we have studied the interface before and after a rapid thermal annealing step. We find the formation of a number of chemical phases at the interface, including VN, metallic vanadium, aluminum oxide, and metallic gold. An interaction mechanism for metal contact formation on the entire n-(Al,Ga)N system is proposed.

  7. O-18 tracer studies of Al2O3 scale formation on NiCrAl alloys

    Science.gov (United States)

    Reddy, K. P. R.; Cooper, A. R.; Smialek, J. L.

    1982-01-01

    Diffusion processes in Al2O3 scales formed on NiCrAl + Zr alloys were studied by the proton activation technique employing the O-18 isotope as a tracer. The O-18 profiles identified a zone of oxide penetration beneath the external scale. Both this subscale formation and the outer Al2O3 scale thickness were shown by this technique to increase with Zr content in the alloy. Estimated kp's from scale thicknesses were in agreement with gravimetric measurements for various Zr levels. Alternate exposures in O-16 and O-18 revealed that oxygen inward transport was the primary growth mechanism. A qualitative analysis of these O-18 profiles indicated that the oxygen transport was primarily via short-circuit paths, such as grain boundaries.

  8. Atrx promotes heterochromatin formation at retrotransposons.

    Science.gov (United States)

    Sadic, Dennis; Schmidt, Katharina; Groh, Sophia; Kondofersky, Ivan; Ellwart, Joachim; Fuchs, Christiane; Theis, Fabian J; Schotta, Gunnar

    2015-07-01

    More than 50% of mammalian genomes consist of retrotransposon sequences. Silencing of retrotransposons by heterochromatin is essential to ensure genomic stability and transcriptional integrity. Here, we identified a short sequence element in intracisternal A particle (IAP) retrotransposons that is sufficient to trigger heterochromatin formation. We used this sequence in a genome-wide shRNA screen and identified the chromatin remodeler Atrx as a novel regulator of IAP silencing. Atrx binds to IAP elements and is necessary for efficient heterochromatin formation. In addition, Atrx facilitates a robust and largely inaccessible heterochromatin structure as Atrx knockout cells display increased chromatin accessibility at retrotransposons and non-repetitive heterochromatic loci. In summary, we demonstrate a direct role of Atrx in the establishment and robust maintenance of heterochromatin.

  9. Induced dicentric chromosome formation promotes genomic rearrangements and tumorigenesis.

    Science.gov (United States)

    Gascoigne, Karen E; Cheeseman, Iain M

    2013-07-01

    Chromosomal rearrangements can radically alter gene products and their function, driving tumor formation or progression. However, the molecular origins and evolution of such rearrangements are varied and poorly understood, with cancer cells often containing multiple, complex rearrangements. One mechanism that can lead to genomic rearrangements is the formation of a "dicentric" chromosome containing two functional centromeres. Indeed, such dicentric chromosomes have been observed in cancer cells. Here, we tested the ability of a single dicentric chromosome to contribute to genomic instability and neoplastic conversion in vertebrate cells. We developed a system to transiently and reversibly induce dicentric chromosome formation on a single chromosome with high temporal control. We find that induced dicentric chromosomes are frequently damaged and mis-segregated during mitosis, and that this leads to extensive chromosomal rearrangements including translocations with other chromosomes. Populations of pre-neoplastic cells in which a single dicentric chromosome is induced acquire extensive genomic instability and display hallmarks of cellular transformation including anchorage-independent growth in soft agar. Our results suggest that a single dicentric chromosome could contribute to tumor initiation.

  10. Ar + induced interfacial mixing and phase formation in the Al/Cr system

    Science.gov (United States)

    Kim, H. K.; Kim, S. O.; Song, J. H.; Kim, K. W.; Woo, J. J.; Whang, C. N.; Smith, R. J.

    1991-07-01

    Evaporated Al/Cr bilayer thin films were irradiated by 80 keV Ar + at doses in the range from 1 × 10 15 to 2 × 10 16 Ar +/cm 2 at room temperature in order to investigate the Ar + induced interfacial mixing behavior and the phase formation and transition by Ar + bombardment. Ion bombardment induces intermixing across the Al/Cr interface and mixing variance increases with increasing ion dose. Cascade and thermal spike models are found to be not adequate for the ion beam mixing mechanism at room temperature in this system. The Al 13Cr 2 phase is formed as an initial phase by ion beam mixing and then transforms into the Al 11Cr 2 or Al 4Cr phases at subsequent ion bombardment. This result is discussed in terms of the enhanced atomic mobility and the thermodynamical driving force by introducing the concept of an effective heat of formation.

  11. Formation of Nanoscale Intermetallic Phases in Ni Surface Layer at High Intensity Implantation of Al Ions

    Institute of Scientific and Technical Information of China (English)

    I.A.Bozhko; S.V.Fortuna; I.A.Kurzina; I.B.Stepanov; E.V.Kozlov; Yu.P. Sharkeev

    2004-01-01

    The results of experimental study of nanoscale intermetallic formation in surface layer of a metal target at ion implantation are presented. To increase the thickness of the ion implanted surface layer the high intensive ion implantation is used. Compared with the ordinary ion implantation, the high intensive ion implantation allows a much thicker modified surface layer. Pure polycrystalline nickel was chosen as a target. Nickel samples were irradiated with Al ions on the vacuum-arc ion beam and plasma flow source "Raduga-5". It was shown that at the high intensity ion implantation the fine dispersed particles of Ni3Al, NiAl intermetallic compounds and solid solution Al in Ni are formed in the nickel surface layer of 200 nm and thicker. The formation of phases takes place in complete correspondence with the Ni-Al phase diagram.

  12. Multi-scale simulation of quantum dot formation in Al/Al (110) homoepitaxy

    Science.gov (United States)

    Tiwary, Yogesh; Fichthorn, Kristen

    2007-03-01

    In experimental studies of Al(110) homoepitaxy, it is observed that over a certain temperature window (330-500K), 3D huts, up to 50 nm high with well defined and smooth (111) and (100) facets, form and self-organize over the micron scale [1]. The factors leading to this kinetic self-organization are currently unclear. To understand how these structures form and evolve, we simulated multi-layer, homoepitaxial growth on Al(110) using ab initio kinetic Monte Carlo (KMC). At the high temperatures, where nano-huts form, the KMC simulations are slow. To tackle this problem, we use a technique developed by Devita & Sander [2], in which isolated adatoms make multiple moves in one step. We achieve high efficiency with this algorithm and we explore very high temperatures on large simulation lattices. We uncover a variety of interesting morphologies (Ripples, mounds, smooth surface, huts) that depend on the growth temperature. By varying the barriers for various rate processes, we discern the factors that determine hut sizes, aspect ratios, and self-organization. [1] F. Buatier de Mongeot, W. Zhu, A. Molle, R. Buzio, C. Boragno, U. Valbusa, E. Wang, and Z. Zhang, Phys. Rev. Lett. 91, 016102 (2003). [2] J.P. Devita & L.M. Sander, Phys. Rev. B 72, 205421 (2005).

  13. Fischer-Tropsch synthesis over ruthenium-promoted Co/Al2O3 catalyst with different reduction procedures

    Institute of Scientific and Technical Information of China (English)

    Ali Karimi; Ali Nakhaei Pour; Farshad Torabi; Behnam Hatami; Ahmad Tavasoli; Mohammad Reza Alaei; Mohammad Irani

    2010-01-01

    The effect of reduction procedure on catalyst properties,activity and products selectivity of ruthenium-promoted Co/γ-Al2O3 catalyst in Fischer-Tropsch synthesis(FTS)was investigated.Catalyst samples were reduced with different reduction gas compositions and passivated before being characterized by TPR and XRD techniques.Different activity and product selectivity analyses were also performed.These results showed that the catalyst dispersion,particle size,and the degree of reduction changed with different reduction gas compositions,which were resulted from the water partial pressures in reduction process that give varying degrees of interaction with the support.It has been suggested that the FTS activity of cobalt catalyst was directly dependent on the catalyst reducibility.A reduction gas with a molar ratio of H2/He = 1 was used to prevent the formation of Co-support compound during catalyst reduction.

  14. Formation Processes of Nanocomposite Strengthening Particles in Rapidly Quenched Al-Sc-Zr Alloys

    Directory of Open Access Journals (Sweden)

    A.V. Kotko

    2012-03-01

    Full Text Available Decomposition processes of supersaturated solid solution of aluminium alloys alloyed with Sc and Zr have been studied in the work. The binary hypereutectic Al-Sc alloys, hyperperitectic Al-Zr alloys and ternary Al-Sc-Zr alloys were chosen. Alloys were obtained by the melt-spinning. Melts were quenched from temperatures of Т = 1000 C and Т = 1400 ºC. The study of the structure of rapidly solidifyed binary Al alloys alloyed with Sc and Zr showed that the crystallization of anomalously supersaturated solid solution (Tquen. = 1400 ºC or the crystallization with the formation of "fan" structure (Tquen. = 1000 ºC are possible depending on the quenching temperature of the melt. The decomposition of anomalously supersaturated solid solution is continuous, with the precipitation of nano-sized spherical Al3X (X-Sc, Zr particles of L12-ordered phase which is isomorphous to matrix. It was found that the loss of thermal stability of Al-Sc alloys is due to the loss of coherence of the strengthening Al3Sc phase. In Al-Zr alloys the loss of strength is due to the formation of a stable tetragonal DO23-ordered A13Zr phase. After co-alloying of Al by Sc and Zr a bimodal grained structure was observed for the hypereutectic ternary alloy (Tquen. = 400ºC. Nano-sized grains of 50-60 nm were present on the boundaries of 1-2 µm large-sized grains. TEM shows the formation of nanocomposite Al3Zr/Al3Sc particles. The formation of Al3Zr shell changes the nature of the interfacial fit of the particle with the matrix and slows down the decomposition during the coalescence. Ternary Al-Sc-Zr alloys have significantly higher thermal stability during aging as compared to binary Al-Sc and Al-Zr alloys. Decomposition processes of supersaturated solid solution of aluminium alloys alloyed with Sc and Zr have been studied in the work. The binary hypereutectic Al-Sc alloys, hyperperitectic Al-Zr alloys and ternary Al-Sc-Zr alloys were chosen. Alloys were

  15. On the formation of U Al alloys in the molten LiCl KCl eutectic

    Science.gov (United States)

    Cassayre, L.; Caravaca, C.; Jardin, R.; Malmbeck, R.; Masset, P.; Mendes, E.; Serp, J.; Soucek, P.; Glatz, J.-P.

    2008-08-01

    U-Al alloy formation has been studied in the temperature range of 400-550 °C by electrochemical techniques in the molten LiCl-KCl eutectic. Cyclic voltammetry showed that underpotential reduction of U(III) onto solid Al occurs at a potential about 0.35 V more anodic than pure U deposition. Open circuit potential measurements, recorded after small depositions of U metal onto the Al electrode, did not allow the distinction between potentials associated with UAl x alloys and the Al rest potential, as they were found to be practically identical. As a consequence, a spontaneous chemical reaction between dissolved UCl 3 and Al is thermodynamically possible and was experimentally observed. Galvanostatic electrolyses were carried out both on Al rods and Al plates. Stable and dense U-Al deposits were obtained with high faradic yields, and the possibility to load the whole bulk of a thin Al plate was demonstrated. The analyses (by SEM-EDX and XRD) of the deposits indicated the formation of different intermetallic phases (UAl 2, UAl 3 and UAl 4) depending on the experimental conditions.

  16. On the formation of U-Al alloys in the molten LiCl-KCl eutectic

    Energy Technology Data Exchange (ETDEWEB)

    Cassayre, L. [Laboratoire de Genie Chimique (LGC), Universite Paul Sabatier, UMR CNRS 5503, 31062 Toulouse cedex 9 (France); Caravaca, C. [CIEMAT, DE/DFN/URAA, Avda. Complutense, 22, Madrid 28040 (Spain); Jardin, R. [European Commission, JRC, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Malmbeck, R. [European Commission, JRC, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany)], E-mail: rikard.malmbeck@ec.europa.eu; Masset, P.; Mendes, E.; Serp, J.; Soucek, P.; Glatz, J.-P. [European Commission, JRC, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany)

    2008-08-15

    U-Al alloy formation has been studied in the temperature range of 400-550 deg. C by electrochemical techniques in the molten LiCl-KCl eutectic. Cyclic voltammetry showed that underpotential reduction of U(III) onto solid Al occurs at a potential about 0.35 V more anodic than pure U deposition. Open circuit potential measurements, recorded after small depositions of U metal onto the Al electrode, did not allow the distinction between potentials associated with UAl{sub x} alloys and the Al rest potential, as they were found to be practically identical. As a consequence, a spontaneous chemical reaction between dissolved UCl{sub 3} and Al is thermodynamically possible and was experimentally observed. Galvanostatic electrolyses were carried out both on Al rods and Al plates. Stable and dense U-Al deposits were obtained with high faradic yields, and the possibility to load the whole bulk of a thin Al plate was demonstrated. The analyses (by SEM-EDX and XRD) of the deposits indicated the formation of different intermetallic phases (UAl{sub 2}, UAl{sub 3} and UAl{sub 4}) depending on the experimental conditions.

  17. Why stellar feedback promotes disc formation in simulated galaxies

    CERN Document Server

    Übler, Hannah; Oser, Ludwig; Aumer, Michael; Sales, Laura V; White, Simon

    2014-01-01

    We study how feedback influences baryon infall onto galaxies using cosmological, zoom-in simulations of haloes with present mass $\\mathrm{M}_{\\mathrm{vir}}=6.9\\times10^{11} \\mathrm{M}_{\\odot}$ to $1.7\\times10^{12} \\mathrm{M}_{\\odot}$. Starting at $z=4$ from identical initial conditions, implementations of weak and strong stellar feedback produce bulge- and disc-dominated galaxies, respectively. Strong feedback favours disc formation: (1) because conversion of gas into stars is suppressed at early times, as required by abundance matching arguments, resulting in flat star formation histories and higher gas fractions; (2) because $50\\%$ of the stars form ${\\it in}$ ${\\it situ}$ from recycled disc gas with angular momentum only weakly related to that of the $z=0$ dark halo; (3) because late-time gas accretion is typically an order of magnitude stronger and has higher specific angular momentum, with recycled gas dominating over primordial infall; (4) because $25-30\\%$ of the total accreted gas is ejected entirely ...

  18. C60 superstructure and carbide formation on the Al-terminated Al9Co2(001 ) surface

    Science.gov (United States)

    Ledieu, J.; Gaudry, É.; de Weerd, M.-C.; Gille, P.; Diehl, R. D.; Fournée, V.

    2015-04-01

    We report the formation of an ordered C60 monolayer on the Al9Co2 (001) surface using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), x-ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and ab initio calculations. Dosing fullerenes at 300 K results in a disordered overlayer. However, the adsorption of C60 with the sample held between 573-673 K leads to a [4, -2 ∣1 ,3 ] phase. The growth of C60 proceeds with the formation of two domains which are mirror symmetric with respect to the [100] direction. Within each domain, the superstructure unit cell contains six molecules and this implies an area per fullerene equal to 91 Å2. The molecules exhibit two types of contrast (bright and dim) which are bias dependent. The adsorption energies and preferred molecular configuration at several possible adsorption sites have been determined theoretically. These calculations lead to a possible scheme describing the configuration of each C60 in the observed superstructure. Several defects (vacancies, protrusions,…) and domain boundaries observed in the film are also discussed. If the sample temperature is higher than 693 K when dosing, impinging C60 molecules dissociate at the surface, hence leading to the formation of a carbide film as observed by STM and LEED measurements. The formation of Al4C3 domains and the molecular dissociation are confirmed by XPS/UPS measurements acquired at different stages of the experiment. The cluster substructure present at the Al9Co2 (001) surface dictates the carbide domain orientations.

  19. Tropoelastin coated PLLA-PLGA scaffolds promote vascular network formation.

    Science.gov (United States)

    Landau, Shira; Szklanny, Ariel A; Yeo, Giselle C; Shandalov, Yulia; Kosobrodova, Elena; Weiss, Anthony S; Levenberg, Shulamit

    2017-04-01

    The robust repair of large wounds and tissue defects relies on blood flow. This vascularization is the major challenge faced by tissue engineering on the path to forming thick, implantable tissue constructs. Without this vasculature, oxygen and nutrients cannot reach the cells located far from host blood vessels. To make viable constructs, tissue engineering takes advantage of the mechanical properties of synthetic materials, while combining them with ECM proteins to create a natural environment for the tissue-specific cells. Tropoelastin, the precursor of the elastin, is the ECM protein responsible for elasticity in diverse tissues, including robust blood vessels. Here, we seeded endothelial cells with supporting cells on PLLA/PLGA scaffolds treated with tropoelastin, and examined the morphology, expansion and maturity of the newly formed vessels. Our results demonstrate that the treated scaffolds elicit a more expanded, complex and developed vascularization in comparison to the untreated group. Implantation of tropoelastin-treated scaffolds into mouse abdominal muscle resulted in enhanced perfusion of the penetrating vasculature and improved integration. This study points to the great potential of these combined materials in promoting the vascularization of implanted engineered constructs, which can be further exploited in the fabrication of clinically relevant engineered tissues.

  20. Native low density lipoprotein promotes lipid raft formation in macrophages.

    Science.gov (United States)

    Song, Jian; Ping, Ling-Yan; Duong, Duc M; Gao, Xiao-Yan; He, Chun-Yan; Wei, Lei; Wu, Jun-Zhu

    2016-03-01

    Oxidized low‑density lipoprotein (LDL) has an important role in atherogenesis; however, the mechanisms underlying cell‑mediated LDL oxidation remain to be elucidated. The present study investigated whether native‑LDL induced lipid raft formation, in order to gain further insight into LDL oxidation. Confocal microscopic analysis revealed that lipid rafts were aggregated or clustered in the membrane, which were colocalized with myeloperoxidase (MPO) upon native LDL stimulation; however, in the presence of methyl‑β‑cyclodextrin (MβCD), LDL‑stimulated aggregation, translocation, and colocalization of lipid rafts components was abolished.. In addition, lipid raft disruptors MβCD and filipin decreased malondialdehyde expression levels. Density gradient centrifugation coupled to label‑free quantitative proteomic analysis identified 1,449 individual proteins, of which 203 were significantly upregulated following native‑LDL stimulation. Functional classification of the proteins identified in the lipid rafts revealed that the expression levels of translocation proteins were upregulated. In conclusion, the results of the present study indicated that native‑LDL induced lipid raft clustering in macrophages, and the expression levels of several proteins were altered in the stimulated macrophages, which provided novel insights into the mechanism underlying LDL oxidation.

  1. Formation of polychlorinated dibenzodioxins, benzenes and phenols from thermal degradation of 2-chlorophenol promoted by CuCl2

    Energy Technology Data Exchange (ETDEWEB)

    Visez, N.; Baillet, C.; Sawerysyn, J.P. [Lille-1 Univ. (France). Physicochimie des Processus de Combustion et de l' Atmosphere - UMR-CNRS

    2004-09-15

    processes of PCDD/Fs from chlorophenols as precursors. These investigations have shown that other organic byproducts, potentially toxic, could also be formed with PCDD/Fs. Born et al. have studied the formation of PCDD/Fs from isomers of monochlorophenol on model and real fly ashes using a fixed bed reactor. The reaction products observed were carbon monoxide, carbon dioxide, 2,4- dichlorophenol, 2,6-dichlorophenol, 2,4,6-trichlorophenol, PCDDs, monobenzofuran, polychlorodiphenylethers, polychlorobenzenes, methylene chloride and tetrachloroethylene. By investigating the PCDD/Fs formation from ortho-chlorinated phenols and copper chloride, Ryu and Mulholland have identified the following products: chlorophenols, chlorobenzenes, PCDD/Fs, tetrachloroethylene and benzoquinones Hell et al. have studied the reaction of 2,4,6-trichlorophenol on real and model fly ash using a fixed bed reactor. They have observed that polychlorobenzenes formation was favored when time and temperature were increased. This work is aimed at highlighting the organic compounds formed by thermal degradation of 2-chlorophenol (2CP) promoted by copper chloride using sealed tubes as closed reactors. It is clear that this experimental method is unrealistic when compared to conditions of industrial processes. However, it enables us to use residence times (from minutes to hours) long enough to get more informations on reactions pathways responsible for PCCD/Fs formation and degradation which would be difficult to obtain from experiments with much smaller residence times.

  2. Core–shell formation in self-induced InAlN nanorods

    Science.gov (United States)

    Palisaitis, J.; Hsiao, C.-L.; Hultman, L.; Birch, J.; Persson, P. O. Å.

    2017-03-01

    We have examined the early stages of self-induced InAlN core–shell nanorod (NR) formation processes on amorphous carbon substrates in plan-view geometry by means of transmission electron microscopy methods. The results show that the grown structure phase separates during the initial moments of deposition into a majority of Al-rich InAlN and a minority of In-enriched InAlN islands. The islands possess polygonal shapes and are mainly oriented along a crystallographic c-axis. The growth proceeds with densification and coalescence of the In-enriched islands, resulting in a base for the In-enriched NR cores with shape transformation to hexagonal. The Al-rich shell formation around such early cores is observed at this stage. The matured core–shell structure grows axially and radially, eventually reaching a steady growth state which is dominated by the axial NR growth. We discuss the NR formation mechanism by considering the adatom surface kinetics, island surface energy, phase separation of InAlN alloys, and incoming flux directions during dual magnetron sputter epitaxy.

  3. Characteristics and formation of [AlO4Al12(OH)24(H2O)12]7+ in electrolysis process

    Institute of Scientific and Technical Information of China (English)

    刘会娟; 曲久辉; 张素娟; 胡承志

    2002-01-01

    [AlO4Al12(OH)24(H2O)12]7+(Al13) formation in electrolysis process is studied. The results detected by 27Al NMR spectroscopy show that high content of Al13 polymer is formed in the partially hydrolyzed aluminum solution prepared by controlled electrolysis process. In the produced electrolyte of total Al concentration (Al) 2.0 mol* L-1 with a basicity (B = OH/Al molar ratios) of 2.0, the content of Al13 polymer is over 60% of total Al. Dynamic light scattering shows that the size distribution of the final electrolyte solutions ( = 2.0 mol*L-1) is trimodal with B = 2.0 and bimodal with B = 2.5. The aggregates of Al13 complexes increase the particle size of partially hydrolyzed aluminum solution.

  4. BRCA1-IRIS overexpression promotes formation of aggressive breast cancers.

    Directory of Open Access Journals (Sweden)

    Yoshiko Shimizu

    breast tumor formation, especially in patients with HER2(+ or TN/BL subtypes. We propose that BRCA1-IRIS inhibition may be pursued as a novel therapeutic option to treat these aggressive breast tumor subtypes.

  5. Thermodynamically destabilized hydride formation in "bulk" Mg-AlTi multilayers for hydrogen storage.

    Science.gov (United States)

    Kalisvaart, Peter; Shalchi-Amirkhiz, Babak; Zahiri, Ramin; Zahiri, Beniamin; Tan, XueHai; Danaie, Mohsen; Botton, Gianluigi; Mitlin, David

    2013-10-21

    Thermodynamic destabilization of MgH2 formation through interfacial interactions in free-standing Mg-AlTi multilayers of overall "bulk" (0.5 μm) dimensions with a hydrogen capacity of up to 5.5 wt% is demonstrated. The interfacial energies of Mg-AlTi and Mg-Ti (examined as a baseline) are calculated to be 0.81 and 0.44 J m(-2). The enhanced interfacial energy of AlTi opens the possibility of creating ultrathin alloy interlayers that provide further thermodynamic improvements in metal hydrides.

  6. Influence of cooling rate on microstructure formation during rapid solidification of binary TiAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kenel, C., E-mail: Christoph.Kenel@empa.ch; Leinenbach, C.

    2015-07-15

    Highlights: • Rapid solidification studies with varying cooling rates were realized for Ti–Al. • Experiments were combined with finite element simulations of heat transfer. • The resulting microstructure of Ti–Al alloys is strongly dependent on the Al content. • The microstructure and phase transformation behavior can be predicted. • The method allows alloy development for processes involving rapid solidification. - Abstract: Titanium aluminides as structural intermetallics are possible candidates for a potential weight reduction and increased performance of high temperature components. A method for the characterization of the microstructure formation in rapidly solidified alloys was developed and applied for binary Ti–(44–48)Al (at.%). The results show a strong dependency of the microstructure on the Al content at cooling rates between 6 ⋅ 10{sup 2} and 1.5 ⋅ 10{sup 4} K s{sup −1}. The formation of α → α{sub 2} ordering, lamellar α{sub 2} + γ colonies and interdendritic TiAl γ-phase were observed, depending on the Al amount. Based on thermodynamic calculations the observed microstructure can be explained using the CALPHAD approach taking into account the non-equilibrium conditions. The presented method provides a useful tool for alloy development for processing techniques involving rapid solidification with varying cooling rates.

  7. On the electrochemical formation of Pu-Al alloys in molten LiCl-KCl

    Science.gov (United States)

    Mendes, E.; Malmbeck, R.; Nourry, C.; Souček, P.; Glatz, J.-P.

    2012-01-01

    Properties of Pu-Al alloys were investigated in connection with development of pyrochemical methods for reprocessing of spent nuclear fuel. Electroseparation techniques in molten LiCl-KCl are being developed in ITU to group-selectively recover actinides from the mixture with fission products. In the process, actinides are electrochemically reduced on solid aluminium cathodes, forming solid actinide-aluminium alloys. This article is focused on electro-chemical characterisation of Pu-Al alloys in molten LiCl-KCl, on electrodeposition of Pu on solid Al electrodes and on determination of chemical composition and structure of the formed alloys. Cyclic voltammetry and chronopotentiometry were used to study Pu-Al alloys in the temperature range 400-550 °C. Pu is reduced to metal in one reduction step Pu 3+/Pu 0 on an inert W electrode. On a reactive Al electrode, the reduction of Pu 3+ to Pu 0 occurs at a more positive potential due to formation of Pu-Al alloys. The open circuit potential technique was used to identify the alloys formed. Stable deposits were obtained by potentiostatic electrolyses of LiCl-KCl-PuCl 3 melts on Al plates. XRD and SEM-EDX analyses were used to characterise the alloys, which were composed mainly of PuAl 4 with some PuAl 3. In addition, the preparation of PuCl 3 containing salt by carbochlorination of PuO 2 is described.

  8. Formation of quasicrystalline phase in Al70-x Ga x Pd17Mn13 alloys

    Science.gov (United States)

    Yadav, T. P.; Singh, Devinder; Shahi, Rohit R.; Shaz, M. A.; Tiwari, R. S.; Srivastava, O. N.

    2011-07-01

    In the present investigation, the formation and stability of icosahedral phase in Al70- x Ga x Pd17Mn13 alloys has been explored using X-ray diffraction, scanning, transmission electron microscopy and energy dispersive X-ray analysis. Cast alloys and melt-spun ribbons with x = 2.5, 5, 7.5, 10, 12.5, 15 and 20 have been investigated. In both cases, the alloys up to 5 at% Ga exhibit the formation of pure icosahedral phase. However, for x ≥5 at% Ga content, the cast alloy exhibits the formation of multiphase material, consisting of an icosahedral phase along with AlPd-type B2 and ξ‧ crystalline (orthorhombic structure with unit cell a = 23.5 Å, b = 16.6 Å and c = 12.4 Å) phases. In the case of the melt spun ribbon for x = 5 at% Ga, only an icosahedral phase has been found, but for 15 > x > 5 at% Ga, an icosahedral phase is the majority phase with AlPd-type B2 phase being the minority component. For x = 15 at% Ga, a Al3Pd2-type hexagonal phase together with a small amount of quasicrystalline phase is formed. However, for x = 20, only a hexagonal Al3Pd2 phase results.

  9. The Kinetics of TiAl3 Formation in Explosively Welded Ti-Al Multilayers During Heat Treatment

    Science.gov (United States)

    Foadian, Farzad; Soltanieh, Mansour; Adeli, Mandana; Etminanbakhsh, Majid

    2016-10-01

    Metallic-intermetallic laminate (MIL) composites, including Ti/TiAl3 composite, are promising materials for many applications, namely, in the aerospace industry. One method to produce Ti/TiAl3 laminate composite is to provide close attachment between desired number of titanium and aluminum plates, so that by applying heat and/or pressure, the formation of intermetallic phases between the layers becomes possible. In this work, explosive welding was used to make a strong bond between six alternative Ti and Al layers. The welded samples were annealed at three different temperatures: 903 K, 873 K, and 843 K (630 °C, 600 °C, and 570 °C) in ambient atmosphere, and the variation of the intermetallic layer thickness was used to study the growth kinetics. Microstructural investigations were carried out on the welded and annealed samples using optical microscopy and scanning electron microscopy equipped with energy-dispersive X-ray spectrometer (EDS). X-ray diffraction (XRD) technique was used to identify the formed intermetallic phases. It was found that at each temperature, two different mechanisms govern the process: reaction controlled and diffusion controlled. The calculated values of activation energies for reaction-controlled and diffusion-controlled mechanisms are 232.1 and 17.4 kJ, respectively.

  10. Network topology for the formation of solvated electrons in binary CaO-Al2O3 composition glasses.

    Science.gov (United States)

    Akola, Jaakko; Kohara, Shinji; Ohara, Koji; Fujiwara, Akihiko; Watanabe, Yasuhiro; Masuno, Atsunobu; Usuki, Takeshi; Kubo, Takashi; Nakahira, Atsushi; Nitta, Kiyofumi; Uruga, Tomoya; Weber, J K Richard; Benmore, Chris J

    2013-06-18

    Glass formation in the CaO-Al2O3 system represents an important phenomenon because it does not contain typical network-forming cations. We have produced structural models of CaO-Al2O3 glasses using combined density functional theory-reverse Monte Carlo simulations and obtained structures that reproduce experiments (X-ray and neutron diffraction, extended X-ray absorption fine structure) and result in cohesive energies close to the crystalline ground states. The O-Ca and O-Al coordination numbers are similar in the eutectic 64 mol % CaO (64CaO) glass [comparable to 12CaO·7Al2O3 (C12A7)], and the glass structure comprises a topologically disordered cage network with large-sized rings. This topologically disordered network is the signature of the high glass-forming ability of 64CaO glass and high viscosity in the melt. Analysis of the electronic structure reveals that the atomic charges for Al are comparable to those for Ca, and the bond strength of Al-O is stronger than that of Ca-O, indicating that oxygen is more weakly bound by cations in CaO-rich glass. The analysis shows that the lowest unoccupied molecular orbitals occurs in cavity sites, suggesting that the C12A7 electride glass [Kim SW, Shimoyama T, Hosono H (2011) Science 333(6038):71-74] synthesized from a strongly reduced high-temperature melt can host solvated electrons and bipolarons. Calculations of 64CaO glass structures with few subtracted oxygen atoms (additional electrons) confirm this observation. The comparable atomic charges and coordination of the cations promote more efficient elemental mixing, and this is the origin of the extended cage structure and hosted solvated (trapped) electrons in the C12A7 glass.

  11. Formation of Au–Al alloy on silicon for polymer modulator electrode application

    Energy Technology Data Exchange (ETDEWEB)

    Yue, Yuanbin; Sun, Jian; Zhao, Xuliang; Xie, Ying; Wang, Xibin; Liang, Lei; Wang, Fei; Chen, Changming; Yi, Yunji; Sun, Xiaoqiang, E-mail: sunxq@jlu.edu.cn; Zhang, Daming

    2014-04-01

    Graphical abstract: - Highlights: • Annealing treatments can be used to form Au–Al alloy in thin films geometry on silicon substrate. • Favorable surface morphology and electrical characteristics can be obtained by optimizing annealing parameters. • Au–Al alloy is competitive to be the electrode of polymer EO modulators confirmed by the measurement of S21 parameter. - Abstract: The formation of aurum–aluminum (Au–Al) alloy on silicon substrate and its use to be electrode of polymer electro-optic (EO) modulator were investigated. The surface morphology and crystallinity were studied by atomic force microscopy, scanning electron microscope, X-ray diffractometer (XRD) and energy dispersive spectrometer. The electrical resistivity was characterized by the four-probe method. XRD pattern confirmed the formation of AuAl phase. After annealed for 11 min at 575 °C, the Au–Al alloy film exhibited a root mean square roughness of less than 40 nm and a minimum electrical resistivity of 2.24 μΩ cm with no obvious change within 6 months. The scattering-parameter (S21) of a fabricated co-planar waveguide electrode polymer EO modulator was measured by vector network analyzer, and a 3-dB bandwidth of 5.2 GHz was observed. These physical properties promise good potentials of Au–Al alloy to be electrode of polymer EO modulators.

  12. Formation and characterization of Al-Ti-Nb alloys by electron-beam surface alloying

    Science.gov (United States)

    Valkov, S.; Petrov, P.; Lazarova, R.; Bezdushnyi, R.; Dechev, D.

    2016-12-01

    The combination of attractive mechanical properties, light weight and resistance to corrosion makes Ti-Al based alloys applicable in many industrial branches, like aircraft and automotive industries etc. It is known that the incorporation of Nb improves the high temperature performance and mechanical properties. In the present study on Al substrate Ti and Nb layers were deposited by DC (Direct Current) magnetron sputtering, followed by electron-beam alloying with scanning electron beam. It was chosen two speeds of the specimen motion during the alloying process: V1 = 0.5 cm/s and V2 = 1 cm/s. The alloying process was realized in circular sweep mode in order to maintain the melt pool further. The obtained results demonstrate a formation of (Ti,Nb)Al3 fractions randomly distributed in biphasic structure of intermetallic (Ti,Nb)Al3 particles, dispersed in α-Al solid solution. The evaluated (Ti,Nb)Al3 lattice parameters are independent of the speed of the specimen motion and therefore the alloying speed does not affect the lattice parameters and thus, does not form additional residual stresses, strains etc. It was found that lower velocity of the specimen motion during the alloying process develops more homogeneous structures. The metallographic analyses demonstrate a formation of surface alloys with very high hardness. Our results demonstrate maximal values of 775 HV [kg/cm2] and average hardness of 673 HV [kg/cm2].

  13. The Mechanism of Mg2Al3 Formation by Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    H. Suwarno

    2009-01-01

    Full Text Available Synthetic and characterization of the Mg2Al3 formation by mechanical alloying have been carried out using a high energy ball milling process. Mechanical alloying is a technique of solid state reactions among two or more metals to form a new alloy through the deformation properties of the metals. The Mg2Al3 alloy was formed by milling the individual constituents using a high energy ball milling under the varied milling time of 10, 20 and 30 h. The refinement results on the x-ray diffraction analysis show that the observation and calculation are fit to each other. After milling for 10, 20 and 30 h the mixed Mg and Al metals are converted into Mg2Al3 at the composition of 71.82, 90.73 and 96.19 wt%. It is concluded that the Mg2Al3 alloy can be performed by high energy mechanical alloying after 30 h of milling. The mechanism of the Mg2Al3 formation is discussed

  14. Preparation and formation mechanism of Al2O3 nanoparticles by reverse microemulsion

    Institute of Scientific and Technical Information of China (English)

    HUANG Ke-long; YIN Liang-guo; LIU Su-qin; LI Chao-jian

    2007-01-01

    Al2O3 nanoparticles were prepared by polyethylene glycol octylphenyl ether(Triton X-100)/n-butyl alcohol/cyclohexane/ water W/O reverse microemulsion. The proper calcination temperature was determined at 1 150 ℃ by thermal analysis of the precursor products. The structures and morphologies of Al2O3 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy and UV-Vis spectra. The influences of mole ratio of water to surfactant on the morphologies and the sizes of the Al2O3 nanoparticles were studied. With the increase of surfactant content, the particles size becomes larger. The agglomeration of nanoparticles was solved successfully. And the formation mechanisms of Al2O3 nanoparticles in the reverse microemulsion were also discussed.

  15. Low-power GaAlAs laser irradiation promotes the proliferation and osteogenic differentiation of stem cells via IGF1 and BMP2.

    Directory of Open Access Journals (Sweden)

    Jyun-Yi Wu

    Full Text Available Low-power laser irradiation (LPLI has been found to induce various biological effects and cellular processes. Also, LPLI has been shown to promote fracture repair. Until now, it has been unclear how LPLI promotes bone formation and fracture healing. The aim of this study was to investigate the potential mechanism of LPLI-mediated enhancement of bone formation using mouse bone marrow mesenchymal stem cells (D1 cells. D1 cells were irradiated daily with a gallium-aluminum-arsenide (GaAlAs laser at dose of 0, 1, 2, or 4 J/cm(2. The lactate dehydrogenase (LDH assay showed no cytotoxic effects of LPLI on D1 cells, and instead, LPLI at 4 J/cm(2 significantly promoted D1 cell proliferation. LPLI also enhanced osteogenic differentiation in a dose-dependent manner and moderately increased expression of osteogenic markers. The neutralization experiments indicated that LPLI regulated insulin-like growth factor 1 (IGF1 and bone morphogenetic protein 2 (BMP2 signaling to promote cell proliferation and/or osteogenic differentiation. In conclusion, our study suggests that LPLI may induce IGF1 expression to promote both the proliferation and osteogenic differentiation of D1 cells, whereas it may induce BMP2 expression primarily to enhance osteogenic differentiation.

  16. Formation of CuAlO2 Film by Ultrasonic Spray Pyrolysis

    Science.gov (United States)

    Iping, S.; Lockman, Zainovia; Hutagalung, S. D.; Kamsul, A.; Matsuda, Atsunori

    2011-10-01

    Smooth, crack free and homogenous CuAlO2 film was produced by chemical solution deposition process via spray pyrolysis technique on a cleaned Si substrate. The precursor solution used was comprised of a mixture of 45.87 mmol Cu(NO3)2.3H2O and 90 mmol Al(NO3)3.9H2O at ratio of Cu:Al = 1.2:1. The precursor solution was placed in a mist chamber and was atomized by a nebulizer to produce precursor mist. The precursor mist was then carried out by Ar gas and was sprayed onto a heated Si. Two main parameters were studied: the distance between the nozzle of the precursor mist chamber and the Si and the temperature of the Si substrate. It appears that from the XRD data, CuAlO2 can be detected for samples prepared by spraying the precursor mist at temperature of > 550 °C with distance between the nozzle and the substrate of 3cm. Reaction of the Cu and Al ions in the mist near the substrate may have promoted the crystallisation of CuAlO2.

  17. Formation of CuAlO{sub 2} Film by Ultrasonic Spray Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Iping, S; Lockman, Zainovia; Hutagalung, S D [School of Materials and Mineral Resources, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Kamsul, A [Gadjah Mada University, Faculty of Mathematics and Natural Resources, Department of Physics, Sekip Utara Bulaksumur 55281 Yogyakarta (Indonesia); Matsuda, Atsunori, E-mail: zainovia@eng.usm.my [Toyohashi University of Technology, Faculty of Engineering, Department of Materials Science, 1-1 Hibarigaoka, Tempakucho, Toyohashi-shi, Aichi 441-8580 (Japan)

    2011-10-29

    Smooth, crack free and homogenous CuAlO{sub 2} film was produced by chemical solution deposition process via spray pyrolysis technique on a cleaned Si substrate. The precursor solution used was comprised of a mixture of 45.87 mmol Cu(NO{sub 3}){sub 2}.3H{sub 2}O and 90 mmol Al(NO{sub 3}){sub 3}.9H{sub 2}O at ratio of Cu:Al = 1.2:1. The precursor solution was placed in a mist chamber and was atomized by a nebulizer to produce precursor mist. The precursor mist was then carried out by Ar gas and was sprayed onto a heated Si. Two main parameters were studied: the distance between the nozzle of the precursor mist chamber and the Si and the temperature of the Si substrate. It appears that from the XRD data, CuAlO{sub 2} can be detected for samples prepared by spraying the precursor mist at temperature of > 550 deg. C with distance between the nozzle and the substrate of 3cm. Reaction of the Cu and Al ions in the mist near the substrate may have promoted the crystallisation of CuAlO{sub 2}.

  18. VEGF incorporated into calcium phosphate ceramics promotes vascularisation and bone formation in vivo

    Directory of Open Access Journals (Sweden)

    E Wernike

    2010-02-01

    Full Text Available Bone formation and osseointegration of biomaterials are dependent on angiogenesis and vascularization. Angiogenic growth factors such as vascular endothelial growth factor (VEGF were shown to promote biomaterial vascularization and enhance bone formation. However, high local concentrations of VEGF induce the formation of malformed, nonfunctional vessels. We hypothesized that a continuous delivery of low concentrations of VEGF from calcium phosphate ceramics may increase the efficacy of VEGF administration.VEGF was co-precipitated onto biphasic calcium phosphate (BCP ceramics to achieve a sustained release of the growth factor. The co-precipitation efficacy and the release kinetics of the protein were investigated in vitro. For in vivo investigations BCP ceramics were implanted into critical size cranial defects in Balb/c mice. Angiogenesis and microvascularization were investigated over 28 days by means of intravital microscopy. The formation of new bone was determined histomorphometrically. Co-precipitation reduced the burst release of VEGF. Furthermore, a sustained, cell-mediated release of low concentrations of VEGF from BCP ceramics was mediated by resorbing osteoclasts. In vivo, sustained delivery of VEGF achieved by protein co-precipitation promoted biomaterial vascularization, osseointegration, and bone formation. Short-term release of VEGF following superficial adsorption resulted in a temporally restricted promotion of angiogenesis and did not enhance bone formation. The release kinetics of VEGF appears to be an important factor in the promotion of biomaterial vascularization and bone formation. Sustained release of VEGF increased the efficacy of VEGF delivery demonstrating that a prolonged bioavailability of low concentrations of VEGF is beneficial for bone regeneration.

  19. Porous anodic film formation on an Al-3.5wt% Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Paez, M. A.; Skeldon, P.; Thompson, G. E.; Saez, M.; Bustos, O.; Monsalve, A.

    2003-07-01

    The morphological development of porous anodic films in the initial stages is examined during anodizing an Al-3,5 wt% Cu alloy in phosphoric acid. Using transmission electron microscopy a sequence of ultramicrotomed anodic sections reveals the dynamic evolution of numerous features in the thickening film in the initial stages of anodizing. The morphological changes in the anodic oxides in the initial stages of its formation appears related to the formation of bubbles during film growth. From Rutherford backscattering spectroscopy (RBS) analysis of the film, the formation of the bubbles is associated with the enrichment of copper in the alloy due to growth of the anodic oxide. On the other hand, during constant current anodizing of Al-Cu in phosphoric acid, the current efficiency is considerably less than that for anodizing super pure aluminium under similar conditions. >From the contrasting results between the charge consumed calculated from RBS and the real charge consumed during anodizing, oxygen gas bubbles generation and copper oxidation seem to be of less importance on the low efficiency for film formation. It is apparent that the main cause of losing efficiency for film growth on Al-Cu is associated with generation of oxygen ar residual second phase, with the development of stresses in the film and, the consequence of these effects on film cracking during film growth. (Author) 10 refs.

  20. Investigation of Formation and Inhibition Mechanism of Cerium Conversion Films on Al 2024 Alloy

    Institute of Scientific and Technical Information of China (English)

    邵敏华; 黄若双; 付燕; 林昌健

    2002-01-01

    To study the mechanism of formation and inhibition of Ce conversion films on Al 2024-T3 alloy, scanning microreference electrode technique (SMRE) is used to probe the potential map on Al 2024-T3 in CeCl3 solution, the localized corrosion of Al alloy decreases with immersion time and disappears finally, which results from the competition of Cl- aggression and Ce3+ inhibition on alloy surface. The results of X-ray photoelectron spectroscopy (XPS) indicate that the Ce conversion films consist of Al2O3, CeO2 and Ce2O3(Ce(OH)3), and CeO2/Ce2O3 ratio decreases with the immersion time. When a critical pH for Ce(OH)3 formation was reached, Ce(OH)3 will precipitate on the micro cathodic area on alloy surface. Consequently, H2O2, the product of the catholic reaction will oxidize a part of Ce(OH)3 to CeO2, which appears a better corrosion resistance for Al alloys.

  1. Enhancement of MgAl2O4 spinel formation from coprecipitated precursor by powder processing

    Indian Academy of Sciences (India)

    Soumen Pal; A K Bandyopadhyay; S Mukherjee; B N Samaddar; P G Pal

    2011-07-01

    Although low temperature fast coprecipitation technique has been used to synthesize stoichiometric (MgO–nAl2O3, = 1) MgAl2O4 spinel forming precursor, delayed spinellization has always been the concern in this process. In this article, the precursor of this ‘fast technique’ has been used for bulk production by further processing by high speed mixing with solvents and mechanical activation by attrition milling in terms of superior spinellization. At 1000°C, MgAl2O4 – -Al2O3 solid solution and MgO phases are formed (spinel formed by 1000°C is regarded as primary spinel). At higher temperatures, due to large agglomerate size, MgO can not properly interact with the exsolved -Al2O3 from spinel solid solution to form secondary spinel; and consequently spinellization gets affected. Solvent treatment and attrition milling of the coprecipitated precursor disintegrate the larger agglomerates into smaller size (effect is more in attrition). Then MgO comes in proper contact with exsolved alumina, and therefore total spinel formation (primary + secondary) is enhanced. Extent of spinellization, for processed calcined samples where some alumina exists as solid solution with spinel, can be determined from the percentage conversion of MgO. Analysis of the processed powders suggests that the 4 h attrited precursor is most effective in terms of nano size (< 25 nm) stoichiometric spinel crystallite formation at ≤ 1100°C.

  2. Application of sacrificial coatings and effect of composition on Al-Al3Ni ultrafine eutectic formation

    Directory of Open Access Journals (Sweden)

    Čelko L.

    2014-01-01

    Full Text Available This paper introduces an unconventional method designed for forming hypereutectic alloys via coating deposition onto the substrate surface and subsequent heat treatment of such systems. The coating was produced from 99.7 wt% nickel powder by means of high velocity oxyfuel (HVOF spraying onto the surface of 99.999 wt% aluminium sheet. The specimens were manufactured immediately after the spraying. Specimens were heat-treated using a differential thermal analysis (DTA apparatus up to a temperature of 900°C and then cooled down to the room temperature in an argon atmosphere with constant heating and cooling rates, under which the NiAl3 intermetallic phase formed within the initial substrate. Two different alloy microstructures consisting of a coarse eutectic and an ultrafine well-dispersed eutectic were produced. The formation processes and resultant microstructures were studied by means of differential thermal analysis, metallography, scanning electron microscopy, energy dispersive microanalysis, and image analysis techniques.

  3. Experimental and Modeling Study of Kinetics for Methane Hydrate Formation with Tetrahydrofuran as Promoter

    Institute of Scientific and Technical Information of China (English)

    Ning Zhengfu; Zhang Shixi; Zhang Qin; Zhen Shuangyi; Chen Guangjin

    2007-01-01

    The kinetics behavior of methane hydrate formation in the presence of tetrahydrofuran (THF) as promoter was studied. A set of experimental equipment was designed and constructed. A series of kinetics data for the formation of methane hydrate in the presence of THF were measured with the isochoric method. The influences of temperature,pressure and liquid flow rate on the methane consumption rate were studied respectively. Based on the Chen-Guo hydrate formation mechanism,a kinetics model for the formation of methane hydrate in the presence of THF by using the dimensionless Gibbs free energy difference of quasi-chemical reaction of basic hydrate formation,,as the driving force was proposed. The model was used to calculate the rate of methane consumption and it was shown that the calculated results were in good agreement with the experimental results.

  4. Kinetics of Ag-rich precipitates formation in Cu-Al-Ag alloys

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, A.T.; Guerreiro, M.R.; Silva, R.A.G

    2004-06-15

    The kinetics of Ag-rich precipitates formation in the Cu-2 wt.% Al alloy with additions of 2, 4, 6, 8, 10 and 12 wt.% Ag was studied using microhardness changes with temperature and time, differential scanning calorimetry (DSC), differential thermal analysis (DTA), scanning electron microscopy (SEM), optical microscopy (OM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The results indicated that an increase in the Ag content decreases the activation energy for Ag-rich precipitates formation, and that it is possible to estimate the values of the diffusion and nucleation activation energies for the Ag precipitates.

  5. Formation of Gd-Al alloy films by a molten salt electrochemical process

    Energy Technology Data Exchange (ETDEWEB)

    Caravaca, C.; Cordoba, G. de [CIEMAT, Departamento de Energia, Madrid (Spain). Div. de Fision Nuclear/URAA

    2008-01-15

    The electrochemistry of molten LiCl-KCl-GdCl{sub 3} at a reactive Al electrode has been studied at 723 to 823 K. Electrochemical techniques such as cyclic voltammetry and chronopotentiometry have been used in order to identify the intermetallic compounds formed. Cyclic voltammetry showed that, while at an inert W electrode GdCl{sub 3} is reduced to Gd metal in a single step at a potential close to the reduction of the solvent, at an Al electrode a shift towards more positive values occurs. This shift of the cathodic potential indicated a reduction of the activity of Gd in Al with respect to that of W, due to the formation of alloys. The surface characterization of samples formed by both galvanostatic and potentiostatic electrolysis has shown the presence of two intermetallic compounds: GdAl{sub 3} and GdAl{sub 2}. Using open-circuit chronopotentiometry it has been possible to measure the potentials at which these compounds are transformed into each other. The values of these potential plateaus, once transformed into e. f. m. values, allowed to determine the thermodynamic properties of the GdAl{sub 3} intermetallic compound. (orig.)

  6. Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.

  7. Penile Gangrene with Abscess Formation after Modified Al-Ghorab Shunt for Idiopathic Ischemic Priapism

    Directory of Open Access Journals (Sweden)

    Beneranda S. Ford-Glanton

    2014-01-01

    Full Text Available Penile gangrene is a rare but unfortunate complication of surgical intervention and priapism shunts. The literature regarding penile gangrene following surgical correction of priapism is sparse, the majority of which dates back to thirty to forty years. Here, we present the case of a 60-year-old man who presented with priapism that required operative management with a modified Al-Ghorab shunt and eventually suffered from complete necrosis of the penis with abscess formation in both corpora cavernosa.

  8. Formation of complex Al-N-C layer in aluminium by successive carbon and nitrogen implantation

    Energy Technology Data Exchange (ETDEWEB)

    Uglov, V.V.; Cherenda, N.N. E-mail: info@research.bsu.unibel.by; Khodasevich, V.V.; Sokol, V.A.; Abramov, I.I.; Danilyuk, A.L.; Wenzel, A.; Gerlach, J.; Rauschenbach, B

    1999-01-01

    The results of Auger electron spectroscopy and transmission electron microscopy of the surface layer of aluminium after successive implantation by carbon and nitrogen ions are presented in this work. The energy of implanted ions is 40 keV. The implantation dose varies in the range (3.3-6.5)x10{sup 17} ions/cm{sup 2}. The findings show that successive implantation leads to the formation of two main layers in aluminium. The first layer is AlNC{sub x} (0AlN structure, where carbon atoms form bonds with nitrogen atoms. The second layer contains disoriented Al{sub 4}C{sub 3} precipitates and carbon atoms migrated from the first layer. The mechanism of migration is discussed.

  9. Formation of complex Al-N-C layer in aluminium by successive carbon and nitrogen implantation

    Science.gov (United States)

    Uglov, V. V.; Cherenda, N. N.; Khodasevich, V. V.; Sokol, V. A.; Abramov, I. I.; Danilyuk, A. L.; Wenzel, A.; Gerlach, J.; Rauschenbach, B.

    1999-01-01

    The results of Auger electron spectroscopy and transmission electron microscopy of the surface layer of aluminium after successive implantation by carbon and nitrogen ions are presented in this work. The energy of implanted ions is 40 keV. The implantation dose varies in the range (3.3-6.5) × 10 17 ions/cm 2. The findings show that successive implantation leads to the formation of two main layers in aluminium. The first layer is AlNC x (0 < x < 0.5) layer with violated hcp. AlN structure, where carbon atoms form bonds with nitrogen atoms. The second layer contains disoriented Al 4C 3 precipitates and carbon atoms migrated from the first layer. The mechanism of migration is discussed.

  10. First principles calculations of formation energies and elastic constants of inclusions α-Al2O3, MgO and AlN in aluminum alloy

    Science.gov (United States)

    Liu, Yu; Huang, Yuanchun; Xiao, Zhengbing; Yang, Chuge; Reng, Xianwei

    2016-05-01

    In this paper, the formation energies and elastic constants of α-Al2O3, MgO and AlN in both rock salt (cubic) and wurtzite (hexagonal) structures were investigated by first principles calculations. The results show that the formation energy being -17.8, -6.3, -3.06 and -3.46 eV/formula unit for α-Al2O3, MgO, AlN (rock salt) and AlN (wurtzite). It suggests that in the ground state, α-Al2O3 is relatively more stable than MgO and AlN. The elastic properties for a polycrystalline in the ground state were calculated with the obtained elastic constants, the elastic properties reveal the rock salt structure AlN is the hardest particles among all the inclusions, and all of these inclusions are classified as brittle materials, which is detrimental to the ductile nature of aluminum matrix. The calculated anisotropy index shows that the AlN (wurtzite) and α-Al2O3 have a lower degree of anisotropy compared with MgO and AlN (rock salt). The calculated results are in good agreement with the values of experimental and other works.

  11. Formation of metastable phases during solidification of Al-3.2 wt% Mn

    Energy Technology Data Exchange (ETDEWEB)

    Khvan, Alexandra V.; Cheverikin, Vladimir V.; Dinsdale, Alan T. [Thermochemistry of Materials SRC, National University of Science and Technology MISIS, 4 Leninsky Prosp., 119049 Moscow (Russian Federation); Watson, Andy [Thermochemistry of Materials SRC, National University of Science and Technology MISIS, 4 Leninsky Prosp., 119049 Moscow (Russian Federation); Institute for Materials Research, School of Chemical and Process Engineering, University of Leeds, LS2 9JT Leeds (United Kingdom); Levchenko, Viktor V.; Zolotorevskiy, Vadim S. [Department of Physical Metallurgy of Non-Ferrous Metals, National University of Science and Technology MISIS, 4 Leninsky Prosp., 119049 Moscow (Russian Federation)

    2015-02-15

    Highlights: • During rapid solidification of Al-Mn alloys, expected phases do not always form. • This has been verified in this study. • Calculations of phase equilibria using thermodynamics can help to explain this. • ‘Stable’ phases are shown to be kinetically inhibited from forming. - Abstract: The solidification of the technologically important Al-rich Al-Mn alloys has been studied both experimentally and by calculation of the phase equilibria. The results of previous experimental studies, which indicated that one or more stable intermetallic phases are suppressed on solidification from the liquid, have been confirmed. It was shown that it is important to consider the formation of Al{sub 11}Mn{sub 4} even though other intermetallic phases have a higher driving force for solidification. It is concluded that while an understanding of the thermodynamic properties of the phases is fundamental to modelling the formation of microstructure associated with solidification, it is necessary to take into account other effects such as the thermodynamic properties at interfaces and their effect on nucleation.

  12. Microstructure and formation mechanism of Ce-based chemical conversion coating on 6063 Al alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Dong-chu; LI Wen-fang; GONG Wei-hui; WU Gui-xiang; WU Jian-feng

    2009-01-01

    In order to accelerate the conversion coating formation on 6063 Al alloy in the Ce(NO3)3 solution, accelerants of chloride and ammonium salt were used. The coating morphology, composition and structure were analyzed with SEM/EDS, EPMA, XPS and XRD. The coating morphology is influenced by the composition, pH value and temperature of the treating solution. The coating composed of metal oxide, metal hydroxide and hydrate appears to be amorphous. The elements in the coating are Al, Ce, O, Mn and Mg, while the Ce element exists in the forms of Ce3+ and Ce4+. The accelerant of chloride can increase the compactness and Ce content of the coating, so the coating corrosion resistance is remarkably improved. A scheme for the electrochemical reaction in the coating formation was proposed, and the potential change in the coating formation was also studied. It is found that chloride can shorten the time period of the first and the second stages in coating formation.

  13. Transcriptional inhibition of the bacteriophage T7 early promoter region by oligonucleotide triple helix formation.

    Science.gov (United States)

    Ross, C; Samuel, M; Broitman, S L

    1992-12-30

    We have identified a purine-rich triplex binding sequence overlapping a -35 transcriptional early promoter region of the bacteriophage T7. Triplex-forming oligonucleotide designed to bind this target was annealed to T7 templates and introduced into in vitro transcription systems under conditions favoring specific initiation from this promoter. These templates demonstrated significant transcriptional inhibition relative to naked genomic templates and templates mixed with non-triplex-forming oligonucleotide. It is suggested that triplex formation along this target interferes with transcriptional initiation, and this mechanism may hold potential to disrupt bacteriophage T7 early transcription in vivo.

  14. SCCmec-associated psm-mec mRNA promotes Staphylococcus epidermidis biofilm formation.

    Science.gov (United States)

    Yang, Yongchang; Zhang, Xuemei; Huang, Wenfang; Yin, Yibing

    2016-10-01

    Biofilm formation is considered the major pathogenic mechanism of Staphylococcus epidermidis-associated nosocomial infections. Reports have shown that SCCmec-associated psm-mec regulated methicillin-resistant Staphylococcus aureus virulence and biofilm formation. However, the role of psm-mec in S. epidermidis remains unclear. To this purpose, we analysed 165 clinical isolates of S. epidermidis to study the distribution, mutation and expression of psm-mec and the relationship between this gene and biofilm formation. Next, we constructed three psm-mec deletion mutants, one psm-mec transgene expression strain (p221) and two psm-mec point mutant strains (pM, pAG) to explore its effects on S. epidermidis biofilm formation. Then, the amount of biofilm formation, extracellular DNA (eDNA) and Triton X-100-induced autolysis of the constructed strains was measured. Results of psm-mec deletion and transgene expression showed that the gene regulated S. epidermidis biofilm formation. Compared with the control strains, the ability to form biofilm, Triton X-100-induced autolysis and the amount of eDNA increased in the p221 strain and the two psm-mec mutants pM and pAG expressed psm-mec mRNA without its protein, whereas no differences were observed among the three constructed strains, illustrating that psm-mec mRNA promoted S. epidermidis biofilm formation through up-regulation of bacterial autolysis and the release of eDNA. Our results reveal that acquisition of psm-mec promotes S. epidermidis biofilm formation.

  15. Investigation of void formation beneath thin AlN layers by decomposition of sapphire substrates for self-separation of thick AlN layers grown by HVPE

    Science.gov (United States)

    Kumagai, Yoshinao; Enatsu, Yuuki; Ishizuki, Masanari; Kubota, Yuki; Tajima, Jumpei; Nagashima, Toru; Murakami, Hisashi; Takada, Kazuya; Koukitu, Akinori

    2010-09-01

    Void formation at the interface between thick AlN layers and (0 0 0 1) sapphire substrates was investigated to form a predefined separation point of the thick AlN layers for the preparation of freestanding AlN substrates by hydride vapor phase epitaxy (HVPE). By heating 50-200 nm thick intermediate AlN layers above 1400 °C in a gas flow containing H 2 and NH 3, voids were formed beneath the AlN layers by the decomposition reaction of sapphire with hydrogen diffusing to the interface. The volume of the sapphire decomposed at the interface increased as the temperature and time of the heat treatment was increased and as the thickness of the AlN layer decreased. Thick AlN layers subsequently grown at 1450 °C after the formation of voids beneath the intermediate AlN layer with a thickness of 100 nm or above self-separated from the sapphire substrates during post-growth cooling with the aid of voids. The 79 μm thick freestanding AlN substrate obtained using a 200 nm thick intermediate AlN layer had a flat surface with no pits, high optical transparency at wavelengths above 208.1 nm, and a dislocation density of 1.5×10 8 cm -2.

  16. Erythropoietin Promotes Bone Formation through EphrinB2/EphB4 Signaling

    OpenAIRE

    Li, C; Shi, C.; Kim, J; Chen, Y.; Ni, S.; Jiang, L.; Zheng, C.; Li, D; J. Hou; Taichman, R. S.; Sun, H

    2015-01-01

    Recent studies have demonstrated that erythropoietin (EPO) has extensive nonhematopoietic biological functions. However, little is known about how EPO regulates bone formation, although several studies suggested that EPO can affect bone homeostasis. In this study, we investigated the effects of EPO on the communication between osteoclasts and osteoblasts through the ephrinB2/EphB4 signaling pathway. We found that EPO slightly promotes osteoblastic differentiation with the increased expression...

  17. EGFR-STAT3 signaling promotes formation of malignant peripheral nerve sheath tumors

    OpenAIRE

    Wu, Jianqiang; Deanna M. Patmore; Jousma, Edwin; Eaves, David W.; Breving, Kimberly; Patel, Ami V.; Schwartz, Eric B.; Fuchs, James R.; Cripe, Timothy P.; Stemmer-Rachamimov, Anat O.; Ratner, Nancy

    2013-01-01

    Malignant peripheral nerve sheath tumors (MPNSTs) develop sporadically or in the context of neurofibromatosis type 1 (NF1). EGFR overexpression has been implicated in MPNST formation, but its precise role and relevant signaling pathways remain unknown. We found that EGFR overexpression promotes mouse neurofibroma transformation to aggressive MPNST (GEM-PNST). Immunohistochemistry demonstrated phosphorylated STAT3 (Tyr705) in both human MPNST and mouse GEM-PNST. A specific JAK2/STAT3 inhibitor...

  18. Characterization of La-promoted Ni/Al2O3 catalysts for hydrogen production from glycerol dry reforming

    Institute of Scientific and Technical Information of China (English)

    Kah; Weng; Siew; Hua; Chyn; Lee; Jolius; Gimbun; Chin; Kui; Cheng

    2014-01-01

    In the current paper, dry(CO2)-reforming of glycerol, a new reforming route, was carried out over alumina(Al2O3)-supported, non-promoted and lanthanum-promoted nickel(Ni) catalysts. Both sets of catalysts were synthesized via a wet co-impregnation procedure. Physicochemical characterization of the catalysts showed that the promoted catalyst possessed smaller metal crystallite size, hence higher metal dispersion compared to the virgin Ni/Al2O3catalyst. This was also corroborated by the surface images captured by the FESEM analysis. From temperature-programmed calcination analysis, the derivative weight profiles revealed two peaks, which represent a water elimination peak at a temperature range of 373 to 473 K followed by nickel nitrate decomposition from 473 to 573 K. In addition, BET surface area measurements gave 85.0 m2 g-1for the non-promoted Ni catalyst, whilst the promoted catalysts showed an average of 1% to 6% improvement depending on the La loadings. Significantly, reaction studies at 873 K showed that glycerol dry reforming successfully produced H2. The 2%La-Ni/Al2O3catalyst, which possessed the largest BET surface area, gave an optimum H2generation(9.70%) at a glycerol conversion of 24.5%.

  19. Cofilin-mediated actin dynamics promotes actin bundle formation during Drosophila bristle development.

    Science.gov (United States)

    Wu, Jing; Wang, Heng; Guo, Xuan; Chen, Jiong

    2016-08-15

    The actin bundle is an array of linear actin filaments cross-linked by actin-bundling proteins, but its assembly and dynamics are not as well understood as those of the branched actin network. Here we used the Drosophila bristle as a model system to study actin bundle formation. We found that cofilin, a major actin disassembly factor of the branched actin network, promotes the formation and positioning of actin bundles in the developing bristles. Loss of function of cofilin or AIP1, a cofactor of cofilin, each resulted in increased F-actin levels and severe defects in actin bundle organization, with the defects from cofilin deficiency being more severe. Further analyses revealed that cofilin likely regulates actin bundle formation and positioning by the following means. First, cofilin promotes a large G-actin pool both locally and globally, likely ensuring rapid actin polymerization for bundle initiation and growth. Second, cofilin limits the size of a nonbundled actin-myosin network to regulate the positioning of actin bundles. Third, cofilin prevents incorrect assembly of branched and myosin-associated actin filament into bundles. Together these results demonstrate that the interaction between the dynamic dendritic actin network and the assembling actin bundles is critical for actin bundle formation and needs to be closely regulated.

  20. Thermodynamic Justification for the Ni/Al/Ni Joint Formation by a Diffusion Brazing

    Directory of Open Access Journals (Sweden)

    Waldemar Wolczynski

    2011-07-01

    Full Text Available

    A theoretical model for the joint formation was developed for the diffusion brazing. The phenomena of dissolution and solidification were included into the model. A thermodynamic justification for the isothermal soldering occurrence in meta-stable conditions was developed. It involved the application of the criterion of higher temperature of the solid / liquid (s/l interface. The dissolution of the filler metal in the substrate was described by the solute concentration within the dissolution zone (liquid film situated at the substrate surface. The selection of the  parameter was justified by the Thermocalc calculation of the Ni-Al phase diagram for meta-stable equilibrium. According to the model assumptions, the solidification was accompanied by undercooled peritectic reactions resulting in formation of the intermetallic phases. The average Al – solute concentration measured across a given Al3Ni2/Al3Ni/Al3Ni2 joint confirmed that the solute concentration was conserved within the joint sub-layers. The Ni-Al phase diagram for meta-stable equilibrium referred to the solidification was also calculated by means of the Thermocalc Software. It allowed to locate the solidification path, s/l interface path and redistribution path onto the mentioned diagram. Superposition of both calculated phase

  1. Nitrite promotes protein carbonylation and Strecker aldehyde formation in experimental fermented sausages: are both events connected?

    Science.gov (United States)

    Villaverde, A; Ventanas, J; Estévez, M

    2014-12-01

    The role played by curing agents (nitrite, ascorbate) on protein oxidation and Strecker aldehyde formation is studied. To fulfill this objective, increasing concentrations of nitrite (0, 75 and 150ppm) and ascorbate (0, 250 and 500ppm) were added to sausages subjected to a 54day drying process. The concurrence of intense proteolysis, protein carbonylation and formation of Strecker aldehydes during processing of sausages suggests that α-aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) may be implicated in the formation of Strecker aldehydes. The fact that nitrite (150ppm, ingoing amount) significantly promoted the formation of protein carbonyls at early stages of processing and the subsequent formation of Strecker aldehydes provides strength to this hypothesis. Ascorbate (125 and 250ppm) controlled the overall extent of protein carbonylation in sausages without declining the formation of Strecker aldehydes. These results may contribute to understanding the chemistry fundamentals of the positive influence of nitrite on the flavor and overall acceptability of cured muscle foods.

  2. Ultraviolet irradiation initiates ectopic foot formation in regenerating hydra and promotes budding

    Indian Academy of Sciences (India)

    Saroj S Ghaskadbi; Leena Shetye; Shashi Chiplonkar; Surendra Ghaskadbi

    2005-03-01

    We have studied the effects of ultraviolet-C (UVC) and Ultraviolet-B (UVB) on growth and pattern formation in Pelmatohydra oligactis. UVC brings about a significant increase in budding in intact hydra while UVB does not exhibit such an effect. Excessive budding could be a response for survival at wavelengths that damage biological tissues. If the head or base piece of a bisected hydra is irradiated and recombined with the unirradiated missing part, regeneration proceeds normally indicating that exposure of a body part with either an intact head or foot to UVC does not influence pattern formation. Most significantly, in the middle piece, but not in the head or the base piece of a trisected hydra, UVC leads to initiation of ectopic feet formation in almost one third of the cases. Thus, UV irradiation interferes with pattern formation in regenerating hydra, possibly by changing positional values, and promotes budding in intact hydra. This is the first report on induction of ectopic feet formation by UV in regenerating hydra and opens up the possibility of using UV irradiation as a tool to understand pattern formation in the enigmatic hydra.

  3. In-situ observation of porosity formation during directional solidification of Al-Si casting alloys

    Directory of Open Access Journals (Sweden)

    Zhao Lei

    2011-02-01

    Full Text Available In-situ observation of porosity formation during directional solidification of two Al-Si alloys (7%Si and 13%Si was made by using of micro-focus X-ray imaging. In both alloys, small spherical pores initially form in the melt far away from the eutectic solid-liquid (S/L interface and then grow and coagulate during solidification. Some pores can float and escape from the solidifying melt front at a relatively high velocity. At the end of solidification, the remaining pores maintain spherical morphology in the near eutectic alloy but become irregular in the hypoeutectic alloy. This is attributed to different solidification modes and aluminum dendrite interactions between the two alloys. The mechanism of the porosity formation is briefly discussed in this paper.

  4. Low nuclear body formation and tax SUMOylation do not prevent NF-kappaB promoter activation

    Directory of Open Access Journals (Sweden)

    Bonnet Amandine

    2012-09-01

    Full Text Available Abstract Background The Tax protein encoded by Human T-lymphotropic virus type 1 (HTLV-1 is a powerful activator of the NF-κB pathway, a property critical for HTLV-1-induced immortalization of CD4+ T lymphocytes. Tax permanently stimulates this pathway at a cytoplasmic level by activating the IκB kinase (IKK complex and at a nuclear level by enhancing the binding of the NF-κB factor RelA to its cognate promoters and by forming nuclear bodies, believed to represent transcriptionally active structures. In previous studies, we reported that Tax ubiquitination and SUMOylation play a critical role in Tax localization and NF-κB activation. Indeed, analysis of lysine Tax mutants fused or not to ubiquitin or SUMO led us to propose a two-step model in which Tax ubiquitination first intervenes to activate IKK while Tax SUMOylation is subsequently required for promoter activation within Tax nuclear bodies. However, recent studies showing that ubiquitin or SUMO can modulate Tax activities in either the nucleus or the cytoplasm and that SUMOylated Tax can serve as substrate for ubiquitination suggested that Tax ubiquitination and SUMOylation may mediate redundant rather than successive functions. Results In this study, we analyzed the properties of a new Tax mutant that is properly ubiquitinated, but defective for both nuclear body formation and SUMOylation. We report that reducing Tax SUMOylation and nuclear body formation do not alter the ability of Tax to activate IKK, induce RelA nuclear translocation, and trigger gene expression from a NF-κB promoter. Importantly, potent NF-κB promoter activation by Tax despite low SUMOylation and nuclear body formation is also observed in T cells, including CD4+ primary T lymphocytes. Moreover, we show that Tax nuclear bodies are hardly observed in HTLV-1-infected T cells. Finally, we provide direct evidence that the degree of NF-κB activation by Tax correlates with the level of Tax ubiquitination, but not

  5. Proneural and abdominal Hox inputs synergize to promote sensory organ formation in the Drosophila abdomen.

    Science.gov (United States)

    Gutzwiller, Lisa M; Witt, Lorraine M; Gresser, Amy L; Burns, Kevin A; Cook, Tiffany A; Gebelein, Brian

    2010-12-15

    The atonal (ato) proneural gene specifies a stereotypic number of sensory organ precursors (SOP) within each body segment of the Drosophila ectoderm. Surprisingly, the broad expression of Ato within the ectoderm results in only a modest increase in SOP formation, suggesting many cells are incompetent to become SOPs. Here, we show that the SOP promoting activity of Ato can be greatly enhanced by three factors: the Senseless (Sens) zinc finger protein, the Abdominal-A (Abd-A) Hox factor, and the epidermal growth factor (EGF) pathway. First, we show that expression of either Ato alone or with Sens induces twice as many SOPs in the abdomen as in the thorax, and do so at the expense of an abdomen-specific cell fate: the larval oenocytes. Second, we demonstrate that Ato stimulates abdominal SOP formation by synergizing with Abd-A to promote EGF ligand (Spitz) secretion and secondary SOP recruitment. However, we also found that Ato and Sens selectively enhance abdominal SOP development in a Spitz-independent manner, suggesting additional genetic interactions between this proneural pathway and Abd-A. Altogether, these experiments reveal that genetic interactions between EGF-signaling, Abd-A, and Sens enhance the SOP-promoting activity of Ato to stimulate region-specific neurogenesis in the Drosophila abdomen.

  6. Effects of Re microalloying on glass formation and mechanical properties of Zr-Cu-Al alloys

    Science.gov (United States)

    Schmitz, S.; Löser, W.; Klauß, H.; Mickel, C.; Büchner, B.

    2013-03-01

    The effect of microalloying with rhenium on a metallic glass-forming alloy (Cu46Zr46Al8)100- x Re x (x = 1, 2) was investigated. Re possesses a positive enthalpy of mixing within the Cu-Re terminal system. Splat quenched foils of ≈40 µm in thickness display an amorphous structure. Their crystallisation temperature increases from T x = 504 to 513°C with addition of Re at nearly constant glass formation temperature T g = 445°C for the amorphous samples. In contrast, injection cast rods consist of B2-CuZr type phase dendrites, minor fractions of a cubic phase CuZrAl, and randomly distributed small particles of a Re-rich phase. This represents a novel concept in microalloying where Re-rich precipitates trigger the B2 phase formation. It leads to a unique combination of mechanical properties for as-cast rods, which display high strength at sizeable plastic deformation up to ε p ≈ 4% and an extended range of work-hardening prior to failure.

  7. Nickel Promotes Biofilm Formation by Escherichia coli K-12 Strains That Produce Curli▿

    Science.gov (United States)

    Perrin, Claire; Briandet, Romain; Jubelin, Gregory; Lejeune, Philippe; Mandrand-Berthelot, Marie-Andrée; Rodrigue, Agnès; Dorel, Corinne

    2009-01-01

    The survival of bacteria exposed to toxic compounds is a multifactorial phenomenon, involving well-known molecular mechanisms of resistance but also less-well-understood mechanisms of tolerance that need to be clarified. In particular, the contribution of biofilm formation to survival in the presence of toxic compounds, such as nickel, was investigated in this study. We found that a subinhibitory concentration of nickel leads Escherichia coli bacteria to change their lifestyle, developing biofilm structures rather than growing as free-floating cells. Interestingly, whereas nickel and magnesium both alter the global cell surface charge, only nickel promotes biofilm formation in our system. Genetic evidence indicates that biofilm formation induced by nickel is mediated by the transcriptional induction of the adhesive curli-encoding genes. Biofilm formation induced by nickel does not rely on efflux mechanisms using the RcnA pump, as these require a higher concentration of nickel to be activated. Our results demonstrate that the nickel-induced biofilm formation in E. coli is an adaptational process, occurring through a transcriptional effect on genes coding for adherence structures. The biofilm lifestyle is obviously a selective advantage in the presence of nickel, but the means by which it improves bacterial survival needs to be investigated. PMID:19168650

  8. Nickel promotes biofilm formation by Escherichia coli K-12 strains that produce curli.

    Science.gov (United States)

    Perrin, Claire; Briandet, Romain; Jubelin, Gregory; Lejeune, Philippe; Mandrand-Berthelot, Marie-Andrée; Rodrigue, Agnès; Dorel, Corinne

    2009-03-01

    The survival of bacteria exposed to toxic compounds is a multifactorial phenomenon, involving well-known molecular mechanisms of resistance but also less-well-understood mechanisms of tolerance that need to be clarified. In particular, the contribution of biofilm formation to survival in the presence of toxic compounds, such as nickel, was investigated in this study. We found that a subinhibitory concentration of nickel leads Escherichia coli bacteria to change their lifestyle, developing biofilm structures rather than growing as free-floating cells. Interestingly, whereas nickel and magnesium both alter the global cell surface charge, only nickel promotes biofilm formation in our system. Genetic evidence indicates that biofilm formation induced by nickel is mediated by the transcriptional induction of the adhesive curli-encoding genes. Biofilm formation induced by nickel does not rely on efflux mechanisms using the RcnA pump, as these require a higher concentration of nickel to be activated. Our results demonstrate that the nickel-induced biofilm formation in E. coli is an adaptational process, occurring through a transcriptional effect on genes coding for adherence structures. The biofilm lifestyle is obviously a selective advantage in the presence of nickel, but the means by which it improves bacterial survival needs to be investigated.

  9. Two cassava promoters related to vascular expression and storage root formation.

    Science.gov (United States)

    Zhang, Peng; Bohl-Zenger, Susanne; Puonti-Kaerlas, Johanna; Potrykus, Ingo; Gruissem, Wilhelm

    2003-12-01

    Cassava ( Manihot esculenta Crantz) storage roots, organs accumulating large amounts of starch, develop from primary roots via secondary growth. The availability of promoters related to storage-root formation is a prerequisite for engineering root traits in cassava. Two cDNAs, c15 and c54, were identified from a storage-root cDNA library of cassava MCol1505 via differential screening. The transcripts of c15 and c54 were detected in storage roots but not in leaves by Northern analysis. Homology analysis of the deduced amino acid sequences showed that C15 is likely to be related to cytochrome P450 proteins, which are involved in the oxidative degradation of various compounds, while C54 may be related to Pt2L4, a cassava glutamic acid-rich protein. The promoter regions of c15 and c54 were isolated from the corresponding clones in a cassava genomic library. A 1,465-bp promoter fragment ( p15/1.5) of c15 and a 1,081-bp promoter region ( p54/1.0) of c54 were translationally fused to the uidA reporter gene, and introduced into cassava and Arabidopsis thaliana (L.) Heynh. The expression patterns of p15/1.5::uidA and p54/1.0::uidA in transgenic plants showed that both promoters are predominantly active in phloem, cambium and xylem vessels of vascular tissues from leaves, stems, and root systems. More importantly, strong beta-glucuronidase activity was also detected in the starch-rich parenchyma cells of transgenic storage roots. Our results demonstrate that the two promoters are related to vascular expression and secondary growth of storage roots in cassava.

  10. Erythropoietin promotes bone formation through EphrinB2/EphB4 signaling.

    Science.gov (United States)

    Li, C; Shi, C; Kim, J; Chen, Y; Ni, S; Jiang, L; Zheng, C; Li, D; Hou, J; Taichman, R S; Sun, H

    2015-03-01

    Recent studies have demonstrated that erythropoietin (EPO) has extensive nonhematopoietic biological functions. However, little is known about how EPO regulates bone formation, although several studies suggested that EPO can affect bone homeostasis. In this study, we investigated the effects of EPO on the communication between osteoclasts and osteoblasts through the ephrinB2/EphB4 signaling pathway. We found that EPO slightly promotes osteoblastic differentiation with the increased expression of EphB4 in ST2 cells. However, EPO increased the expression of Nfatc1 and ephrinB2 but decreased the expression of Mmp9 in RAW264.7 cells, resulting in an increase of ephrinB2-expressing osteoclasts and a decrease in resorption activity. The stimulation of ephrinB2/EphB4 signaling via ephrinB2-Fc significantly promoted EPO-mediated osteoblastic differentiation in ST2 cells. EphB4 knockdown through EphB4 shRNA inhibited EPO-mediated osteoblastic phenotypes. Furthermore, in vivo assays clearly demonstrated that EPO efficiently induces new bone formation in the alveolar bone regeneration model. Taken together, these results suggest that ephrinB2/EphB4 signaling may play an important role in EPO-mediated bone formation.

  11. Neuroprotection of lipoic acid treatment promotes angiogenesis and reduces the glial scar formation after brain injury.

    Science.gov (United States)

    Rocamonde, B; Paradells, S; Barcia, J M; Barcia, C; García Verdugo, J M; Miranda, M; Romero Gómez, F J; Soria, J M

    2012-11-01

    After trauma brain injury, a large number of cells die, releasing neurotoxic chemicals into the extracellular medium, decreasing cellular glutathione levels and increasing reactive oxygen species that affect cell survival and provoke an enlargement of the initial lesion. Alpha-lipoic acid is a potent antioxidant commonly used as a treatment of many degenerative diseases such as multiple sclerosis or diabetic neuropathy. Herein, the antioxidant effects of lipoic acid treatment after brain cryo-injury in rat have been studied, as well as cell survival, proliferation in the injured area, gliogenesis and angiogenesis. Thus, it is shown that newborn cells, mostly corresponded with blood vessels and glial cells, colonized the damaged area 15 days after the lesion. However, lipoic acid was able to stimulate the synthesis of glutathione, decrease cell death, promote angiogenesis and decrease the glial scar formation. All those facts allow the formation of new neural tissue. In view of the results herein, lipoic acid might be a plausible pharmacological treatment after brain injury, acting as a neuroprotective agent of the neural tissue, promoting angiogenesis and reducing the glial scar formation. These findings open new possibilities for restorative strategies after brain injury, stroke or related disorders.

  12. Formation of NiAl intermetallic coatings on stainless steel by a conventional duplex process

    Energy Technology Data Exchange (ETDEWEB)

    Ashrafizadeh, F.; Hajdaie, A.H.; Miraghaie, S. [Isfahan Univ. of Technology, Dept. of Materials Engineering, Isfahan (Iran, Islamic Republic of)

    2003-07-01

    Nickel-aluminide coatings were formed on 403 stainless steel samples by a duplex process incorporating electro-deposition and diffusion coating. Nickel was deposited by conventional electroplating on some specimens to appropriate thickness. The uncoated and nickel-coated samples were then aluminized by a powder pack method. Process parameters including pack composition, temperature, coating and annealing cycles were optimized in terms of the intermetallic phases produced in the near surface layers. The coatings and interface regions were characterized by optical and scanning electron microscopy, x-ray diffraction, glow discharge spectroscopy, micro-hardness measurements and pin-on-disc wear testing. Experimental results indicate that deposition of nickel on 403 steel before aluminizing produced two distinct layers of NiAl and FeAl on the surface and below that, respectively. The formation of these phases depends on the coating and annealing temperatures. The intermetallic phase NiAl on steel substrate acts as an alumina forming material to increase the life of aluminized layer. The intermetallic coatings produced by this duplex process had dense structure and excellent adhesion to the substrate; these are suitable candidates for high temperature applications of steel components under oxidation and hot corrosion conditions. (author)

  13. Inner-shell promotions in low-energy Li+-Al collisions at clean and alkali-covered Al(100) surfaces

    Science.gov (United States)

    German, K. A. H.; Weare, C. B.; Yarmoff, J. A.

    1994-11-01

    Spectra of scattered ions and ion-induced electron emissions are used to investigate the electronic processes that occur during 0.4-5.0-keV Li+ bombardment of clean and alkali-atom-covered Al(100). The results show that Li 1s electrons are promoted during hard Li-Al collisions, but not during Li-K or Li-Na collisions. Consequences of the inner-shell electron promotions are evident in the inelastic loss, neutralization behavior, and electron emissions of the scattered Li particles. Spectra of scattered Li+ ions exhibit discrete-loss features, which are resistant to the usual increase in resonant neutralization that accompanies the deposition of alkali atoms on the surface. The loss features are due to Li 1s excitation via electron promotion, while the production of ions away from the surface via autoionization is responsible for their lack of response to alkali-atom adsorption. Spectra of ion-induced electron emissions confirm that Li*(1s2s2) is produced and that it undergoes autoionization.

  14. The MgO-Al2O3-SiO2 system - Free energy of pyrope and Al2O3-enstatite. [in earth mantle formation

    Science.gov (United States)

    Saxena, S. K.

    1981-01-01

    The model of fictive ideal components is used to determine Gibbs free energies of formation of pyrope and Al2O3-enstatite from the experimental data on coexisting garnet and orthopyroxene and orthopyroxene and spinel in the temperature range 1200-1600 K. It is noted that Al2O3 forms an ideal solution with MgSiO3. These thermochemical data are found to be consistent with the Al2O3 isopleths that could be drawn using most recent experimental data and with the reversed experimental data on the garnet-spinel field boundary.

  15. Atomic scale analysis of phase formation and diffusion kinetics in Ag/Al multilayer thin films

    Science.gov (United States)

    Aboulfadl, Hisham; Gallino, Isabella; Busch, Ralf; Mücklich, Frank

    2016-11-01

    Thin films generally exhibit unusual kinetics leading to chemical reactions far from equilibrium conditions. Binary metallic multilayer thin films with miscible elements show some similar behaviors with respect to interdiffusion and phase formation mechanisms. Interfacial density, lattice defects, internal stresses, layer morphologies and deposition conditions strongly control the mass transport between the individual layers. In the present work, Ag/Al multilayer thin films are used as a simple model system, in which the effects of the sputtering power and the bilayer period thickness on the interdiffusion and film reactions are investigated. Multilayers deposited by DC magnetron sputtering undergo calorimetric and microstructural analyses. In particular, atom probe tomography is extensively used to provide quantitative information on concentration gradients, grain boundary segregations, and reaction mechanisms. The magnitude of interdiffusion was found to be inversely proportional to the period thickness for the films deposited under the same conditions, and was reduced using low sputtering power. Both the local segregation at grain boundaries as well as pronounced non-equilibrium supersaturation effects play crucial roles during the early stages of the film reactions. For multilayers with small periods of 10 nm supersaturation of the Al layers with Ag precedes the polymorphic nucleation and growth of the hcp γ-Ag2Al phase. In larger periods the γ phase formation is triggered at junctions between grain boundaries and layers interfaces, where the pathway to heterogeneous nucleation is local supersaturation. Other Ag-rich phases also form as intermediate phases due to asymmetric diffusion rates of parent phases in the γ phase during annealing.

  16. Enthalpy of formation of quasicrystalline phase and ternary solid solutions in the Al-Fe-Cu system

    Institute of Scientific and Technical Information of China (English)

    I.A. Tomilin; S.D. Kaloshkin; V. V. Tcherdyntsev

    2006-01-01

    Standard enthalpies of formation of quasicrystalline phase and the ternary solid solutions in the Al-Fe-Cu system and the intermetallic compound FeAl were determined by the means of solution calorimetry. The quasicrystalline phase was prepared using two different methods. The first method (Ⅰ) consisted of ball milling the mixture of powders of pure aluminum copper and iron in a planetary mill with subsequent compacting by hot pressing and annealing. The second method (Ⅱ) consisted of arc melting of the components in argon atmosphere followed by annealing. The latter method was used for preparing the compound FeAl and the solid solutions. The phases were identified using the XRD method. The enthalpy of the formation was determined for the quasicrystalline phase of the composition Al62Cu25.5Fe12.5 and the ternary BCC solid solutions Al35Cu14Fe51, Al40Cu17Fe43, and Al50.4Cu19.6Fe30. The measured enthalpy of formation of the intermetallic com pound FeAl is in good agreement with the earlier published data. The enthaipies of formation of the quasicrystalline phases prepared using two different methods are close to each other, namely, -22.7±3.4 (method Ⅰ) and -21.3±2.1 (method Ⅱ)k J/mol.

  17. Formation of CoAl2O4 Nanoparticles via Low-Temperature Solid-State Reaction of Fine Gibbsite and Cobalt Precursor

    Directory of Open Access Journals (Sweden)

    Natpakan Srisawad

    2012-01-01

    Full Text Available Nanocrystalline cobalt aluminate (CoAl2O4 was synthesized by the solid-state reaction method with cobalt chloride hexahydrate (CoCl2 · 6H2O as the source of Co and gibbsite (Al(OH3 as the source of Al, respectively. The effects of particle size of the starting fine gibbsite (0.6 and 13 μm and calcination temperatures (450, 550, and 650°C on the properties of CoAl2O4 were investigated by means of X-ray diffraction (XRD, thermogravimetry analysis and differential thermal analysis (TG/DTA, X-ray photoelectron spectroscopy (XPS, UV-visible absorption spectroscopy (UV-Vis, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Increasing of calcination temperature promoted the insertion amounts of Co2+ in alumina matrix in CoAl2O4 structure, which resulted in the brighter blue particles and increasing of UV spectra band. The lowest temperature for the formation of nanocrystalline CoAl2O4 particles was 550°C for the solid-state reaction of cobalt chloride and 0.6 μm fine gibbsite.

  18. The Formation of γ—AlON Spinel in the Reaction of Al2O3—AlN—MgO System

    Institute of Scientific and Technical Information of China (English)

    LIYawei; YUANRunzhang; 等

    1997-01-01

    The stabilization of γ-aluminium oxyni-tride spinel(γ-AlON) has been investigated by addition of MgO,MgAl2O4,etc.,in reaction process.The results indicated that there are wider solid solution areas near ,Al2O3-rich side in AlN-Al2O3-MgO ternary systems,The content of stabilized AlON phase in samples is related to heating temperatures,additives,etc.The lattice parameters of their AlON phases could be well describedby the equation: a0=0.7900+0.0375[MgO]+0.015[AlN](nm)

  19. High-Frequency Promoter Firing Links THO Complex Function to Heavy Chromatin Formation

    DEFF Research Database (Denmark)

    Mouaikel, John; Causse, Sébastien Z; Rougemaille, Mathieu;

    2013-01-01

    The THO complex is involved in transcription, genome stability, and messenger ribonucleoprotein (mRNP) formation, but its precise molecular function remains enigmatic. Under heat shock conditions, THO mutants accumulate large protein-DNA complexes that alter the chromatin density of target genes...... (heavy chromatin), defining a specific biochemical facet of THO function and a powerful tool of analysis. Here, we show that heavy chromatin distribution is dictated by gene boundaries and that the gene promoter is necessary and sufficient to convey THO sensitivity in these conditions. Single...

  20. Promoter-Specific Effects of DREADD Modulation on Hippocampal Synaptic Plasticity and Memory Formation

    OpenAIRE

    Lopez, AJ; Kramar, E; Matheos, DP; White, AO; Kwapis, J; Vogel-Ciernia, A; Sakata, K.; Espinoza, M; Wood, MA

    2016-01-01

    Designer receptors exclusively activated by designer drug (DREADDs) are a novel tool with the potential to bidirectionally drive cellular, circuit, and ultimately, behavioral changes. We used DREADDs to evaluate memory formation in a hippocampus-dependent task in mice and effects on synaptic physiology in the dorsal hippocampus. We expressed neuron-specific (hSyn promoter) DREADDs that were either excitatory (HM3D) or inhibitory (HM4D) in the dorsal hippocampus. As predicted, hSyn–HM3D was ab...

  1. Ordered nano-scale dimple pattern formation on a titanium alloy (Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Yue Wang

    2012-09-01

    Full Text Available Due to the many applications of nanostructured surfaces – including in biomaterials – there is a strong interest in cost- and time-efficient methods for their fabrication. Previously, our group established a simple electrochemical method generating nanoscale patterns on large areas of a number of different metal surfaces. They consist of dimples that are around 6-10 nm deep and hexagonally closed packed with a tunable periodicity of around 50 nm. Ordering requires careful tuning of the surface chemistry, which makes the translation of these findings to multi-component alloys non-obvious. Here, we demonstrate for the first time that such a pattern can also be achieved on the surface of an alloy, namely Ti-6Al-4V. This alloy is of particular interest for biomedical implants. While dimple formation on the main component metals titanium and aluminum has previously been reported (albeit under conditions that differ from each other, we now also report dimple formation on pure vanadium surfaces to occur under very different conditions. Dimple formation occurs preferentially on the (dominant α-phase grains of the alloy. The size of dimples of the alloy material is subject to the electropolishing potential, electrolyte concentration and surface chemical composition, which gives us the opportunity to control the surface features. Since a main application of this alloy are biomedical implants, this level of control will be an important tool for accommodating cell growth.

  2. Inter-organizational relationships: promoters and restrictive factors in the formation of cooperation network

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Gaspar

    2014-04-01

    Full Text Available The present paper had as aim to identify factors of inter-organizational relationships which promotes and restricts the formation of companies’ cooperation network, from two levels of analysis (organizational and inter-organizational. To achieve this goal, it was developed a descriptive-qualitative study, with prospecting for primary and secondary data on a cooperation network. The universe was composed by 41 participating companies associated to the analyzed network. The sampling procedure was for researcher’s accessibility and convenience. As a result, it was identified that the network is guided by goals of cooperation among the participating companies, in addition to representing the sector and provide services in the interests of the associates. The main factors influencing the formation of the network were: business center, marketing and training; but only training has been achieved satisfactorily. The business center and marketing factors have not yet been fully developed, being both identified as restrictive factors.

  3. Sfp-type PPTase inactivation promotes bacterial biofilm formation and ability to enhance wheat drought tolerance

    Directory of Open Access Journals (Sweden)

    Salme eTimmusk

    2015-05-01

    Full Text Available Paenibacillus polymyxa is a common soil bacterium with broad range of practical applications. An important group of secondary metabolites in P. polymyxa are nonribosomal peptide and polyketide derived metabolites (NRP/PK. Modular nonribosomal peptide synthetases catalyse main steps in the biosynthesis of the complex secondary metabolites. Here we report on the inactivation of an A26 sfp-type phosphopantetheinyl transferase. The inactivation of the gene resulted in loss of NRP/PK production. In contrast to the former Bacillus spp. model the mutant strain compared to wild type showed greatly enhanced biofilm formation ability. Its biofilm promotion is directly mediated by NRP/PK, as exogenous addition of the wild type metabolite extracts restores its biofilm formation level. Wheat inoculation with bacteria that had lost their sfp-type PPTase gene resulted in two times higher plant survival and about three times increased biomass under severe drought stress compared to wild type.

  4. ENVIRONMENTALLY FRIENDLY COMPLEXONES. THE THERMODYNAMIC CHARACTERISTICS OF THE FORMATION OF AL3+ ION COMPLEXES WITH ETHYLENEDIAMINEDISUCCINIC ACID IN AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    L.N. Tolkacheva

    2012-06-01

    Full Text Available Complex formation between Al3+ and ethylenediamine - N,N`-disuccinic acid (H4L was studied at 25°C against the background of 0.1, 0.5, 1.0 N solutions of KNO3 by potentiometry and mathematical modeling. The extrapolation of concentration constants to zero ionic strength was used to calculate the thermodynamic constants of the formation of the AlL–, AlHL complexes using an equation with one individual parameter (logβ0 = 16.27 ± 0.07, 9.19 ± 0.2 respectively.

  5. Promoting exclusive {alpha}-Al{sub 2}O{sub 3} growth upon high-temperature oxidation of NiCrAl alloys: experiment versus model predictions

    Energy Technology Data Exchange (ETDEWEB)

    Nijdam, T.J. [Department of Materials Science and Engineering, Delft University of Technology, Rotterdamseweg 137, 2628 AL Delft (Netherlands); Jeurgens, L.P.H. [Department of Materials Science and Engineering, Delft University of Technology, Rotterdamseweg 137, 2628 AL Delft (Netherlands); Sloof, W.G. [Department of Materials Science and Engineering, Delft University of Technology, Rotterdamseweg 137, 2628 AL Delft (Netherlands)]. E-mail: w.g.sloof@tnw.tudelft.nl

    2005-04-15

    The relationships between the compositional changes in the alloy and the morphology and phase constitution of the developing oxide scale are established as a function of oxidation time for the thermal oxidation of a {gamma}-Ni-27Cr-9Al (at.%) alloy at 1373 K and a high and low partial oxygen pressure (pO{sub 2}) of 2 x 10{sup 4} and 0.1 Pa, respectively. Based on experimental observations, and model calculations using a coupled thermodynamic-kinetic oxidation model, four successive growth stages can be identified for the oxidation of a {gamma}-Ni-27Cr-9Al alloy at 1373 K. It is shown that the exclusive growth of {alpha}-Al{sub 2}O{sub 3} is promoted for oxidation at low pO{sub 2} by maintaining a sufficiently high concentration of Al in the alloy at the oxide/metal interface during the initial stages of fast oxide-scale growth.

  6. Proneural proteins Achaete and Scute associate with nuclear actin to promote formation of external sensory organs.

    Science.gov (United States)

    Hsiao, Yun-Ling; Chen, Yu-Ju; Chang, Yi-Jie; Yeh, Hsiao-Fong; Huang, Yi-Chun; Pi, Haiwei

    2014-01-01

    Basic helix-loop-helix (bHLH) proneural proteins promote neurogenesis through transcriptional regulation. Although much is known about the tissue-specific regulation of proneural gene expression, how proneural proteins interact with transcriptional machinery to activate downstream target genes is less clear. Drosophila proneural proteins Achaete (Ac) and Scute (Sc) induce external sensory organ formation by activating neural precursor gene expression. Through co-immunoprecipitation and mass spectrometric analyses, we found that nuclear but not cytoplasmic actin associated with the Ac and Sc proteins in Drosophila S2 cells. Daughterless (Da), the common heterodimeric partner of Drosophila bHLH proteins, was observed to associate with nuclear actin through proneural proteins. A yeast two-hybrid assay revealed that the binding specificity between actin and Ac or Sc was conserved in yeast nuclei without the presence of additional Drosophila factors. We further show that actin is required in external sensory organ formation. Reduction in actin gene activity impaired proneural-protein-dependent expression of the neural precursor genes, as well as formation of neural precursors. Furthermore, increased nuclear actin levels, obtained by expression of nucleus-localized actin, elevated Ac-Da-dependent gene transcription as well as Ac-mediated external sensory organ formation. Taken together, our in vivo and in vitro observations suggest a novel link for actin in proneural-protein-mediated transcriptional activation and neural precursor differentiation.

  7. Autophagy is induced by anti-neutrophil cytoplasmic Abs and promotes neutrophil extracellular traps formation.

    Science.gov (United States)

    Sha, Li-Li; Wang, Huan; Wang, Chen; Peng, Hong-Ying; Chen, Min; Zhao, Ming-Hui

    2016-11-01

    Dysregulated neutrophil extracellular traps (NETs) formation contributes to the pathogenesis of anti-neutrophil cytoplasmic Ab (ANCA)-associated vasculitis (AAV). Increasing evidence indicates that autophagy is involved in the process of NETs formation. In this study, we aimed to investigate whether ANCA could induce autophagy in the process of NETs formation. Autophagy was detected using live cell imaging, microtubule-associated protein light chain 3B (LC3B) accumulation and Western blotting. The results showed that autophagy vacuolization was detected in neutrophils treated with ANCA-positive IgG by live cell imaging. This effect was enhanced by rapamycin, the autophagy inducer, and weakened by 3-methyladenine (3-MA), the autophagy inhibitor. In line with these results, the autophagy marker, LC3B, showed a punctate distribution pattern in the neutrophils stimulated with ANCA-positive IgG. In the presence of rapamycin, LC3B accumulation was further increased; however, this effect was attenuated by 3-MA. Moreover, incubated with ANCA-positive IgG, the NETosis rate significantly increased compared with the unstimulated group. And, the rate significantly increased or decreased in the neutrophils pretreated with rapamycin or 3-MA, respectively, as compared with the cells incubated with ANCA-positive IgG. Overall, this study demonstrates that autophagy is induced by ANCA and promotes ANCA-induced NETs formation.

  8. Incorporation of RANKL promotes osteoclast formation and osteoclast activity on β-TCP ceramics.

    Science.gov (United States)

    Choy, John; Albers, Christoph E; Siebenrock, Klaus A; Dolder, Silvia; Hofstetter, Wilhelm; Klenke, Frank M

    2014-12-01

    β-Tricalcium phosphate (β-TCP) ceramics are approved for the repair of osseous defects. In large defects, however, the substitution of the material by authentic bone is inadequate to provide sufficient long-term mechanical stability. We aimed to develop composites of β-TCP ceramics and receptor activator of nuclear factor κ-B ligand (RANKL) to enhance the formation of osteoclasts and promote cell mediated calcium phosphate resorption. RANKL was adsorbed superficially onto β-TCP ceramics or incorporated into a crystalline layer of calcium phosphate by the use of a co-precipitation technique. Murine osteoclast precursors were seeded onto the ceramics. After 15 days, the formation of osteoclasts was quantified cytologically and colorimetrically with tartrate-resistant acidic phosphatase (TRAP) staining and TRAP activity measurements, respectively. Additionally, the expression of transcripts encoding the osteoclast gene products cathepsin K, calcitonin receptor, and of the sodium/hydrogen exchanger NHA2 were quantified by real-time PCR. The activity of newly formed osteoclasts was evaluated by means of a calcium phosphate resorption assay. Superficially adsorbed RANKL did not induce the formation of osteoclasts on β-TCP ceramics. When co-precipitated onto β-TCP ceramics RANKL supported the formation of mature osteoclasts. The development of osteoclast lineage cells was further confirmed by the increased expression of cathepsin K, calcitonin receptor, and NHA2. Incorporated RANKL stimulated the cells to resorb crystalline calcium phosphate. Our in vitro study shows that RANKL incorporated into β-TCP ceramics induces the formation of active, resorbing osteoclasts on the material surface. Once formed, osteoclasts mediate the release of RANKL thereby perpetuating their differentiation and activation. In vivo, the stimulation of osteoclast-mediated resorption may contribute to a coordinated sequence of material resorption and bone formation. Further in vivo studies

  9. Cyclic architecture of a carbonate sequence, early Aptian Shuaiba formation, Al Huwaisah field, Oman

    Energy Technology Data Exchange (ETDEWEB)

    Groetsch, J. (Shell Research, Rijswijk (Netherlands))

    1993-09-01

    Sequence stratigraphy of carbonates is a topic of ongoing controversy. In particular, small-scale shallowing-upward cycles can provide some key information needed for interpretation of carbonate sequences and/or third-order sea level changes. The early Aptian Shuaiba Formation in the Al Huwaisah field consists of about 90 m of shallow-water limestones. Throughout the formation, an overall decreasing influx of fine detritus is notable toward the top. The sequence can be subdivided into a basal unit and an overlying unit. Both units are composed of meter-scale shallowing-upward cycles of different composition, which can be recognized in core and well logs. Fourier analysis of the first principle component of a set of well logs (GR, FDC, CNL, Sonic) revealed an abrupt change in spectral behavior between the two units. Toward the top, the spectra are [open quotes]cleaning upward[close quotes] with an increasing pronunciation of a peak grouping of 1: 2: 5, suggesting a better preservation of orbital variations in the upper unit. Preservation of orbital forcing in shallowing-upward cycles requires rapid rates of sedimentation. In addition, increased shallow-water carbonate production on the platform is indicated by the appearance of reefal organisms. Hence, a higher rate of sedimentation and therefore a faster aggradation of the platform is inferred for the upper unit, which could have resulted from an increased rate of relative sea level rise. The sudden facies differentiation on the broad Arabian shelf in the upper part of the early Aptian reflects the development of an intrashelf basin. Changes in rate of relative sea level rise on the Arabian shelf might explain the repeated alternation from an easily correlatable ramp-type sedimentation, with slightly higher input of fine terrigenous sediment (e.g., lower unit of Shuaiba Formation) and a differentiation into platform and intrashelf basin facies due to faster aggradation (e.g., upper unit of Shuaiba Formation).

  10. Formation of Al2O3/FeAl coatings on a 9Cr-1Mo steel, and corrosion evaluation in flowing Pb-17Li loop

    Science.gov (United States)

    Majumdar, Sanjib; Paul, Bhaskar; Chakraborty, Poulami; Kishor, Jugal; Kain, Vivekanand; Dey, Gautam Kumar

    2017-04-01

    Iron aluminide coating layers were formed on a ferritic martensitic grade 9Cr-1Mo (P 91) steel using pack aluminizing process. The formation of different aluminide compositions such as orthorhombic-Fe2Al5, B2-FeAl and A2-Fe(Al) on the pack chemistry and heat treatment conditions have been established. About 4-6 μm thick Al2O3 scale was formed on the FeAl phase by controlled heat treatment. The corrosion tests were conducted using both the FeAl and Al2O3/FeAl coated specimens in an electro-magnetic pump driven Pb-17Li Loop at 500 °C for 5000 h maintaining a flow velocity of 1.5 m/s. The detailed characterization studies using scanning electron microscopy, back-scattered electron imaging and energy dispersive spectrometry revealed no deterioration of the coating layers after the corrosion tests. Self-healing oxides were formed at the cracks generated in the aluminide layers during thermal cycling and protected the base alloy (steel) from any kind of elemental dissolution or microstructural degradation.

  11. Adhesion, activation, and aggregation of blood platelets and biofilm formation on the surfaces of titanium alloys Ti6Al4V and Ti6Al7Nb.

    Science.gov (United States)

    Walkowiak-Przybyło, M; Klimek, L; Okrój, W; Jakubowski, W; Chwiłka, M; Czajka, A; Walkowiak, B

    2012-03-01

    Titanium alloys are still on the top list of fundamental materials intended for dental, orthopedics, neurological, and cardiovascular implantations. Recently, a special attention has been paid to vanadium-free titanium alloy, Ti6Al7Nb, that seems to represent higher biocompatibility than traditional Ti6Al4V alloy. Surprisingly, these data are not thoroughly elaborated in the literature; particularly there is a lack of comparative experiments conducted simultaneously and at the same conditions. Our study fills these shortcomings in the field of blood contact and microbiological colonization. To observe platelets adhesion and biofilm formation on the surfaces of compared titanium alloys, fluorescence microscope Olympus GX71 and scanning electron microscope HITACHI S-3000N were used. Additionally, flow cytometry analysis of platelets aggregation and activation in the whole blood after contact with sample surface, as an essential tool for biomaterial thrombocompatibility assessment, was proposed. As a result of our study it was demonstrated that polished surfaces of Ti6Al7Nb and Ti6Al4V alloys after contact with whole citrated blood and E. coli bacterial cells exhibit a considerable difference. Overall, it was established that Ti6Al4V has distinct tendency to higher thrombogenicity, more excessive bacterial biofilm formation and notable cytotoxic properties in comparison to Ti6Al7Nb. However, we suggest these studies should be extended for other types of cells and biological objects.

  12. Bound transcription factor suppresses photoproduct formation in the NF-kappa B promoter.

    Science.gov (United States)

    Ghosh, R; Paniker, L; Mitchell, D L

    2001-01-01

    The relationship between purified transcription factor p50 binding and ultraviolet light-induced DNA damage formation in the NF-kappa B promoter element was investigated. The effect of bound transcription factor on cyclobutane dimer formation was quantified using Maxam-Gilbert analysis of irradiated substrate digested with T4 phage endonuclease V. Two methods were employed for cleaving (6-4) photoproducts. Sites of (6-4) photoproducts cleaved by piperidine showed a general suppression in the presence of bound p50 protein similar to that observed for cyclobutane dimers. In contrast to piperidine, digestion with ultraviolet damage endonuclease (UVDE) from Saccharomyces pombe subsequent to cyclobutane dimer reversal by photolyase displayed a broader spectrum of damaged sites. Whereas some of these sites were suppressed by bound p50 protein, some remained unaffected and one site showed increased (6-4) photoproduct induction. These data illustrate the advantage of UVDE over piperidine for studying (6-4) photoproducts at the sequence level and suggest that this approach may be useful for footprinting transcription factor binding in other promoters.

  13. Subinhibitory concentrations of triclosan promote Streptococcus mutans biofilm formation and adherence to oral epithelial cells.

    Science.gov (United States)

    Bedran, Telma Blanca Lombardo; Grignon, Louis; Spolidorio, Denise Palomari; Grenier, Daniel

    2014-01-01

    Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs) of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.

  14. Subinhibitory concentrations of triclosan promote Streptococcus mutans biofilm formation and adherence to oral epithelial cells.

    Directory of Open Access Journals (Sweden)

    Telma Blanca Lombardo Bedran

    Full Text Available Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.

  15. Mechanical strain promotes osteoblast ECM formation and improves its osteoinductive potential

    Directory of Open Access Journals (Sweden)

    Guo Yong

    2012-10-01

    Full Text Available Abstract Background The extracellular matrix (ECM provides a supportive microenvironment for cells, which is suitable as a tissue engineering scaffold. Mechanical stimulus plays a significant role in the fate of osteoblast, suggesting that it regulates ECM formation. Therefore, we investigated the influence of mechanical stimulus on ECM formation and bioactivity. Methods Mouse osteoblastic MC3T3-E1 cells were cultured in cell culture dishes and stimulated with mechanical tensile strain. After removing the cells, the ECMs coated on dishes were prepared. The ECM protein and calcium were assayed and MC3T3-E1 cells were re-seeded on the ECM-coated dishes to assess osteoinductive potential of the ECM. Results The cyclic tensile strain increased collagen, bone morphogenetic protein 2 (BMP-2, BMP-4, and calcium levels in the ECM. Compared with the ECM produced by unstrained osteoblasts, those of mechanically stimulated osteoblasts promoted alkaline phosphatase activity, elevated BMP-2 and osteopontin levels and mRNA levels of runt-related transcriptional factor 2 (Runx2 and osteocalcin (OCN, and increased secreted calcium of the re-seeded MC3T3-E1 cells. Conclusion Mechanical strain promoted ECM production of osteoblasts in vitro, increased BMP-2/4 levels, and improved osteoinductive potential of the ECM. This study provided a novel method to enhance bioactivity of bone ECM in vitro via mechanical strain to osteoblasts.

  16. Interruptions between the triple helix peptides can promote the formation of amyloid-like fibrils

    Science.gov (United States)

    Parmar, Avanish; Hwang, Eileen; Brodsky, Barbara

    2010-03-01

    It has been reported that collagen can initiate or accelerate the formation of amyloid fibrils. Non-fibrillar collagen types have sites where the repeating (Gly-Xaa-Yaa)n sequences are interrupted by non- Gly-Xaa-Yaa sequences, and we are investigating the hypothesis that some of these interruptions can promote amyloid formation. Our experimental data show that model peptides containing an 8 or 9 residue interruption sequence between (Gly-Pro-Hyp)n domains have a strong propensity for self association to form fibrous structures. A peptide containing only the 9-residue interruption sequence forms amyloid like fibrils with anti-parallel β sheet. Computational analysis predicts that 33 out of 374 naturally occurring human non-fibrillar collagen sequences within or between triple-helical sequences have significant cross-β aggregation potential, including the 8 and 9 residue sequences studied in peptides. Further studies are in progress to investigate whether a triple-helix peptide promotes amyloidogenesis and whether amyloid interferes with collagen fibrillogenesis.

  17. Nucleoporin translocated promoter region (Tpr) associates with dynein complex, preventing chromosome lagging formation during mitosis.

    Science.gov (United States)

    Nakano, Hiroshi; Funasaka, Tatsuyoshi; Hashizume, Chieko; Wong, Richard W

    2010-04-01

    Gain or loss of whole chromosomes is often observed in cancer cells and is thought to be due to aberrant chromosome segregation during mitosis. Proper chromosome segregation depends on a faithful interaction between spindle microtubules and kinetochores. Several components of the nuclear pore complex/nucleoporins play critical roles in orchestrating the rapid remodeling events that occur during mitosis. Our recent studies revealed that the nucleoporin, Rae1, plays critical roles in maintaining spindle bipolarity. Here, we show association of another nucleoporin, termed Tpr (translocated promoter region), with the molecular motors dynein and dynactin, which both orchestrate with the spindle checkpoints Mad1 and Mad2 during cell division. Overexpression of Tpr enhanced multinucleated cell formation. RNA interference-mediated knockdown of Tpr caused a severe lagging chromosome phenotype and disrupted spindle checkpoint proteins expression and localization. Next, we performed a series of rescue and dominant negative experiments to confirm that Tpr orchestrates proper chromosome segregation through interaction with dynein light chain. Our data indicate that Tpr functions as a spatial and temporal regulator of spindle checkpoints, ensuring the efficient recruitment of checkpoint proteins to the molecular motor dynein to promote proper anaphase formation.

  18. Glass Formation Ability and Kinetics of the Gd55Al20Ni25 Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    JO Chol-Lyong; XIA Lei; DING Ding; DONG Yuan-Da

    2006-01-01

    @@ We report a new bulk glass-forming alloy Gd55Al20Ni25. The bulk sample of the alloy is prepared in the shape of rods in diameter 2mm by suction casting. The rod exhibits typical amorphous characteristics in the xray diffraction pattern, paramagnetic property at 300K, distinct glass transition and multi-step crystallization behaviour in differential scanning calorimetry traces. The glass formation ability of the alloy is investigated by using the reduced glass transition temperature Tγg and the parameter γ. Kinetics of glass transition and primary crystallization is also studied. The fragility parameter m obtained from the Vogel-Fulcher-Tammann dependence of glass transition temperature Tg on ln φ (φ is the heating rate) classifies the bulk metallic glasses into the intermediate category according to Angells classification.

  19. Laminin/β1 integrin signal triggers axon formation by promoting microtubule assembly and stabilization

    Institute of Scientific and Technical Information of China (English)

    Wen-Liang Lei; Shi-Ge Xing; Cai-Yun Deng; Xiang-Chun Ju; Xing-Yu Jiang; Zhen-Ge Luo

    2012-01-01

    Axon specification during neuronal polarization is closely associated with increased microtubule stabilization in one of the neurites of unpolarized neuron,but how this increased microtubule stability is achieved is unclear.Here,we show that extracellular matrix (ECM) component laminin promotes neuronal polarization via regulating directional microtubule assembly through β1 integrin (Itgb1).Contact with laminin coated on culture substrate or polystyrene beads was sufficient for axon specification of undifferentiated neurites in cultured hippocampal neurons and cortical slices.Active Itgb1 was found to be concentrated in laminin-contacting neurites.Axon formation was promoted and abolished by enhancing and attenuating Itgbl signaling,respectively.Interestingly,laminin contact promoted plus-end microtubule assembly in a manner that required Itgbl.Moreover,stabilizing microtubules partially prevented polarization defects caused by ltgbl downregulation.Finally,genetic ablation of ltgbl in dorsal telencephalic progenitors caused deficits in axon development of cortical pyramidal neurons.Thus,laminin/Itgb1 signaling plays an instructive role in axon initiation and growth,both in vitro and in vivo,through the regulation of microtubule assembly.This study has established a linkage between an extrinsic factor and intrinsic cytoskeletai dynamics during neuronal polarization.

  20. Formation of Omega-like Nanocrystalline in the Melt-Spun Nd85Al15 Alloy by Phase Transformation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Microstructure and subsequent phase transformations on heating of the melt-spun Nd85Al15 alloy have been studied by X-ray diffraction, transmission electron microscopy and differential scanning calorimetry. The melt-spunNds5Al15 alloy shows two-stage transformation processes as follows: amorphous+72 nm supersaturated bcc-Nd(Al)solid solution→7 nm omega-like phase→AlNd3+hexagonal Nd. The activation energies for the first and secondtransformation were found to be 100 k J/mol and 188 k J/mol, respectively. The formation mechanism of nanoscaleomega-like phase is discussed.

  1. Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al

    Institute of Scientific and Technical Information of China (English)

    LIU Rangsu; DONG Kejun; LIU Fengxiang; ZHENG Caixing; LIU Hairong; LI Jiyong

    2005-01-01

    A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12 0 12 0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals.

  2. Three-dimensional nanoscale study of Al segregation and quantum dot formation in GaAs/AlGaAs core-shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, L.; Blum, I.; Vurpillot, F.; Rigutti, L., E-mail: lorenzo.rigutti@univ-rouen.fr [Groupe de Physique des Matériaux, UMR CNRS 6634, University and INSA of Rouen, Normandie University, 76800 St. Etienne du Rouvray (France); Fontana, Y.; Conesa-Boj, S.; Francaviglia, L.; Russo-Averchi, E.; Heiss, M.; Morral, A. Fontcuberta i [Laboratoire des Matériaux Semiconducteurs, École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland); Arbiol, J. [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, CAT (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, CAT (Spain)

    2014-12-15

    GaAs/Al-GaAs core-shell nanowires fabricated by molecular beam epitaxy contain quantum confining structures susceptible of producing narrow photoluminescence (PL) and single photons. The nanoscale chemical mapping of these structures is analyzed in 3D by atom probe tomography (APT). The study allows us to confirm that Al atoms tend to segregate within the AlGaAs shells towards the vertices of the hexagons defining the nanowire cross section. We also find strong alloy fluctuations remaining AlGaAs shell, leading occasionally to the formation of quantum dots (QDs). The PL emission energies predicted in the framework of a 3D effective mass model for a QD analyzed by APT and the PL spectra measured on other nanowires from the same growth batch are consistent within the experimental uncertainties.

  3. Charge carrier mobility and electronic properties of Al(Op3: impact of excimer formation

    Directory of Open Access Journals (Sweden)

    Andrea Magri

    2015-05-01

    Full Text Available We have studied the electronic properties and the charge carrier mobility of the organic semiconductor tris(1-oxo-1H-phenalen-9-olatealuminium(III (Al(Op3 both experimentally and theoretically. We experimentally estimated the HOMO and LUMO energy levels to be −5.93 and −3.26 eV, respectively, which were close to the corresponding calculated values. Al(Op3 was successfully evaporated onto quartz substrates and was clearly identified in the absorption spectra of both the solution and the thin film. A structured steady state fluorescence emission was detected in solution, whereas a broad, red-shifted emission was observed in the thin film. This indicates the formation of excimers in the solid state, which is crucial for the transport properties. The incorporation of Al(Op3 into organic thin film transistors (TFTs was performed in order to measure the charge carrier mobility. The experimental setup detected no electron mobility, while a hole mobility between 0.6 × 10−6 and 2.1 × 10−6 cm2·V−1·s−1 was measured. Theoretical simulations, on the other hand, predicted an electron mobility of 9.5 × 10−6 cm2·V−1·s−1 and a hole mobility of 1.4 × 10−4 cm2·V−1·s−1. The theoretical simulation for the hole mobility predicted an approximately one order of magnitude higher hole mobility than was observed in the experiment, which is considered to be in good agreement. The result for the electron mobility was, on the other hand, unexpected, as both the calculated electron mobility and chemical common sense (based on the capability of extended aromatic structures to efficiently accept and delocalize additional electrons suggest more robust electron charge transport properties. This discrepancy is explained by the excimer formation, whose inclusion in the multiscale simulation workflow is expected to bring the theoretical simulation and experiment into agreement.

  4. Sinusoidal electromagnetic fields promote bone formation and inhibit bone resorption in rat femoral tissues in vitro.

    Science.gov (United States)

    Zhou, Jian; Ma, Xiao-Ni; Gao, Yu-Hai; Yan, Juan-Li; Shi, Wen-Gui; Xian, Cory J; Chen, Ke-Ming

    2016-01-01

    Effects of sinusoidal electromagnetic fields (SEMFs) on bone metabolism have not yet been well defined. The present study investigated SEMF effects on bone formation and resorption in rat femur bone tissues in vitro. Cultured femur diaphyseal (cortical bone) and metaphyseal (trabecular bone) tissues were treated with 50 Hz 1.8 mT SEMFs 1.5 h per day for up to 12 days and treatment effects on bone formation and resorption markers and associated gene expression were examined. Treatment with SEMFs caused a significant increase in alkaline phosphatase (ALP) activity and inhibited the tartrate-resistant acid phosphatase (TRACP) activity in the femoral diaphyseal or metaphyseal tissues. SEMFs also significantly increased levels of mRNA expression of osterix (OSX), insulin-like growth factor (IGF-1) and ALP in the bone tissues. SEMF treatment decreased glucose content and increased lactic acid contents in the culture conditioned medium. In addition, treatment with SEMFs decreased mRNA expression levels of bone resorption-related genes TRACP, macrophage colony stimulating factor (M-CSF) and cathepsin K (CTSK) in the cultured bone tissues. In conclusion, the current study demonstrated that treatment with 1.8 mT SEMFs at 1.5 h per day promoted bone formation, increased metabolism and inhibited resorption in both metaphyseal and diaphyseal bone tissues in vitro.

  5. Amyloid Aβ 42, a promoter of magnetite nanoparticle formation in Alzheimer’s disease

    Science.gov (United States)

    Bogachan Tahirbegi, Islam; Pardo, Wilmer Alfonso; Alvira, Margarita; Mir, Mònica; Samitier, Josep

    2016-11-01

    The accumulation of iron oxides—mainly magnetite—with amyloid peptide is a key process in the development of Alzheimer’s disease (AD). However, the mechanism for biogeneration of magnetite inside the brain of someone with AD is still unclear. The iron-storing protein ferritin has been identified as the main magnetite-storing molecule. However, accumulations of magnetite in AD are not correlated with an increase in ferritin, leaving this question unresolved. Here we demonstrate the key role of amyloid peptide Aβ 42, one of the main hallmarks of AD, in the generation of magnetite nanoparticles in the absence of ferritin. The capacity of amyloid peptide to bind and concentrate iron hydroxides, the basis for the formation of magnetite, benefits the spontaneous synthesis of these nanoparticles, even under unfavorable conditions for their formation. Using scanning and transmission electron microscopy, electron energy loss spectroscopy and magnetic force microscopy we characterized the capacity of amyloid peptide Aβ 42 to promote magnetite formation.

  6. Constraints from $^{26}Al$ Measurements on the Galaxy's Recent Global Star Formation Rate and Core Collapse Supernovae Rate

    CERN Document Server

    Timmes, F X; Hartmann, D H

    1997-01-01

    Gamma-rays from the decay of $^{26}$Al offer a stringent constraint on the Galaxy's global star formation rate over the past million years, supplementing other methods for quantifying the recent Galactic star formation rate, such as equivalent widths of H$\\alpha$ emission. Advantages and disadvantages of using $^{26}$Al gamma-ray measurements as a tracer of the massive star formation rate are analyzed. Estimates of the Galactic $^{26}$Al mass derived from COMPTEL measurements are coupled with a simple, analytical model of the $^{26}$Al injection rate from massive stars and restrict the Galaxy's recent star formation rate to \\hbox{5 $\\pm$ 4 M\\sun yr$^{-1}$}. In addition, we show that the derived $^{26}$Al mass implies a present day \\hbox{Type II + Ib} supernovae rate of 3.4 $\\pm$ 2.8 per century, which seems consistent with other independent estimates of the Galactic core collapse supernova rate. If some independent measure of the massive star initial mass function or star formation rate or \\hbox{Type II + Ib}...

  7. The formation of different Mg-Al LDHs (Mg/Al=2:1 under hydrothermal conditions and their application for Zn2+ ions removal

    Directory of Open Access Journals (Sweden)

    Bankauskaite A.

    2014-01-01

    Full Text Available The formation of different Mg-Al LDHs (Mg/Al = 2:1 under hydrothermal conditions (200°C; 4-24 h was investigated in the 4MgCO3⋅Mg(OH2⋅5H2O - γ-Al2O3/Al(OH3 - H2O and Mg5(CO34(OH2•4H2O - γ-Al2O3 - H2O systems. It was determined that chemical nature of the initial Mg containing components changes the formation mechanism of the synthesis products during isothermal curing. Magnesium aluminum hydroxide hydrate is crystallized by using 4MgCO3⋅Mg(OH2⋅5H2O as starting material while hydroxide hydrate in the Mg5(CO34(OH2•4H2O presence. The sequence of the compounds formation is presented. It should be noted that different modifications of Al containing components have only a slight influence on the meixnerite-type LDH hydrothermal synthesis. It was determined that after 45 min of sorption all Zn2+ ions are incorporated into the crystal structure of hydrotalcite. It should be underlined that crystallinity of the latter compound do not change during ion exchange experiments. Thus, the latter compound can be used as adsorbent for Zn2+ ion removal. Synthesized samples were characterized by powder X-Ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, simultaneous thermal analysis (STA and scanning electron microscopy (SEM.

  8. Formation of crystalline Zn-Al layered double hydroxide precipitates on γ-alumina: the role of mineral dissolution.

    Science.gov (United States)

    Li, Wei; Livi, Kenneth J T; Xu, Wenqian; Siebecker, Matthew G; Wang, Yujun; Phillips, Brian L; Sparks, Donald L

    2012-11-06

    To better understand the sequestration of toxic metals such as nickel (Ni), zinc (Zn), and cobalt (Co) as layered double hydroxide (LDH) phases in soils, we systematically examined the presence of Al and the role of mineral dissolution during Zn sorption/precipitation on γ-Al(2)O(3) (γ-alumina) at pH 7.5 using extended X-ray absorption fine structure spectroscopy (EXAFS), high-resolution transmission electron microscopy (HR-TEM), synchrotron-radiation powder X-ray diffraction (SR-XRD), and (27)Al solid-state NMR. The EXAFS analysis indicates the formation of Zn-Al LDH precipitates at Zn concentration ≥0.4 mM, and both HR-TEM and SR-XRD reveal that these precipitates are crystalline. These precipitates yield a small shoulder at δ(Al-27) = +12.5 ppm in the (27)Al solid-state NMR spectra, consistent with the mixed octahedral Al/Zn chemical environment in typical Zn-Al LDHs. The NMR analysis provides direct evidence for the existence of Al in the precipitates and the migration from the dissolution of γ-alumina substrate. To further address this issue, we compared the Zn sorption mechanism on a series of Al (hydr)oxides with similar chemical composition but differing dissolubility using EXAFS and TEM. These results suggest that, under the same experimental conditions, Zn-Al LDH precipitates formed on γ-alumina and corundum but not on less soluble minerals such as bayerite, boehmite, and gibbsite, which point outs that substrate mineral surface dissolution plays an important role in the formation of Zn-Al LDH precipitates.

  9. Influence of Inelastic Collisions with Hydrogen Atoms on the Formation of Al I and Si I Lines in Stellar Spectra

    CERN Document Server

    Mashonkina, Lyudmila; Shi, Jianrong

    2016-01-01

    The non-LTE line formation for Al I and Si I was calculated with model atmospheres corresponding to F-G-K type stars of different metallicity. To account for inelastic collisions with H I, for the first time we applied the cross sections calculated by Belyaev et al. using model approaches within the formalism of the Born-Oppenheimer quantum theory. For Al I non-LTE leads to overionization in the line formation layers and to weakened spectral lines, in line with earlier non-LTE studies. However, in contrast to the previuos studies, our results predict smaller magnitude of the non-LTE effects for the subordinate lines. Owing to large cross sections, the ion-pair production and mutual neutralization processes Al I(nl) + H I(1s) $\\leftrightarrow$ Al~II(3s^2) + H^- provide a close coupling of high-excitation Al I levels to the Al II ground state, which causes smaller deviations from the TE populations compared to the case of pure electron collisions. For three metal-poor stars, the Al abundance was determined from...

  10. Formation of composites fabricated by exothermic dispersion reaction in Al-TiO2-B2O3 system

    Institute of Scientific and Technical Information of China (English)

    ZHU He-guo; WANG Heng-zhi; GE Liang-qi; CHEN Shi; WU Shen-qing

    2007-01-01

    The formation of aluminum matrix composites fabricated by exothermic dispersion reaction in Al-TiO2-B2O3 system was investigated. The thermal analysis results show that the reactions are spontaneous and exothermic. The Gibbs free energy of α-Al2O3 is the lowest among all the combustion products, followed by TiB2 and Al3Ti. It is noted that when the B2O3/TiO2 mole ratio is below 1, the reaction products are composed of particle-like α-Al2O3, TiB2 and rod-like Al3Ti. The α-Al2O3 crystallites, resulting from the reaction between Al and TiO2 or B2O3, are segregated at the grain boundaries due to a lower wettability with the matrix. SEM micrographs show that rod-like Al3Ti phase distributes uniformly in the matrix. When the B2O3/TiO2 mole ratio is around 1, the Al3Ti phase almost disappears in the composites, and the distribution of α-Al2O3 particulates is improved evidently.

  11. Interface structure and formation mechanism of diffusion-bonded joints of TiAl-based alloy to titanium alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Vacuum diffusion bonding of a TiAl-based alloy (TAD) to a titanium alloy (TC2) was carried out at 1 273 K for 15~120 min under a pressure of 25 MPa. The kinds of the reaction products and the interface structures of the joints were investigated by SEM, EPMA and XRD. Based on this, a formation mechanism of the interface structure was elucidated. Experimental and analytical results show that two reaction layers have formed during the diffusion bonding of TAD to TC2. One is Al-rich α(Ti)layer adjacent to TC2,and the other is (Ti3Al+TiAl)layer adjacent to TAD,thus the interface structure of the TAD/TC2 joints is TAD/(Ti3Al+TiAl)/α(Ti)/TC2.This interface structure forms according to a three-stage mechanism,namely(a)the occurrence of a single-phase α(Ti)layer;(b)the occurrence of a duplex-phase(Ti3Al+TiAl)layer;and(c)the growth of the α(Ti)and (Ti3Al+TiAl)layers.

  12. Monoallelic loss of the imprinted gene Grb10 promotes tumor formation in irradiated Nf1+/- mice.

    Directory of Open Access Journals (Sweden)

    Rana Mroue

    2015-05-01

    Full Text Available Imprinted genes are expressed from only one parental allele and heterozygous loss involving the expressed allele is sufficient to produce complete loss of protein expression. Genetic alterations are common in tumorigenesis but the role of imprinted genes in this process is not well understood. In earlier work we mutagenized mice heterozygous for the Neurofibromatosis I tumor suppressor gene (NF1 to model radiotherapy-associated second malignant neoplasms that arise in irradiated NF1 patients. Expression analysis of tumor cell lines established from our mouse models identified Grb10 expression as widely absent. Grb10 is an imprinted gene and polymorphism analysis of cell lines and primary tumors demonstrates that the expressed allele is commonly lost in diverse Nf1 mutant tumors arising in our mouse models. We performed functional studies to test whether Grb10 restoration or loss alter fundamental features of the tumor growth. Restoring Grb10 in Nf1 mutant tumors decreases proliferation, decreases soft agar colony formation and downregulates Ras signaling. Conversely, Grb10 silencing in untransformed mouse embryo fibroblasts significantly increased cell proliferation and increased Ras-GTP levels. Expression of a constitutively activated MEK rescued tumor cells from Grb10-mediated reduction in colony formation. These studies reveal that Grb10 loss can occur during in vivo tumorigenesis, with a functional consequence in untransformed primary cells. In tumors, Grb10 loss independently promotes Ras pathway hyperactivation, which promotes hyperproliferation, an early feature of tumor development. In the context of a robust Nf1 mutant mouse model of cancer this work identifies a novel role for an imprinted gene in tumorigenesis.

  13. Formation of Al/B4C Surface Nano-composite Layers on 7075 Al Alloy Employing Friction Stir Processing

    Science.gov (United States)

    Kashani-Bozorg, S. F.; Jazayeri, K.

    2009-06-01

    Al/B4C surface nano-composite layers was achieved on commercial 7075 Al substrate employing friction stir processing technique. Agglomeration of B4C particles was occurred after a single pass. The dispersion of B4C particles was found to be affected by the number of FSP passes. A distribution of nano-size B4C particle was achieved after four passes. Moreover, the increasing in number of FSP passes causes a decreasing in matrix grain size of the surface nano-composite layer. The micro hardness of the surface nano-composite layer improves by almost two times as compared to that of the as-received substrate; this is attributed to the finer matrix grains and dispersion of nano-sized B4C particles.

  14. LaAlO3 stoichiometry is key to electron liquid formation at LaAlO3/SrTiO3 interfaces

    Science.gov (United States)

    Warusawithana, M. P.; Richter, C.; Mundy, J. A.; Roy, P.; Ludwig, J.; Paetel, S.; Heeg, T.; Pawlicki, A. A.; Kourkoutis, L. F.; Zheng, M.; Lee, M.; Mulcahy, B.; Zander, W.; Zhu, Y.; Schubert, J.; Eckstein, J. N.; Muller, D. A.; Hellberg, C. Stephen; Mannhart, J.; Schlom, D. G.

    2013-08-01

    Emergent phenomena, including superconductivity and magnetism, found in the two-dimensional electron liquid (2-DEL) at the interface between the insulators lanthanum aluminate (LaAlO3) and strontium titanate (SrTiO3) distinguish this rich system from conventional 2D electron gases at compound semiconductor interfaces. The origin of this 2-DEL, however, is highly debated, with focus on the role of defects in the SrTiO3, while the LaAlO3 has been assumed perfect. Here we demonstrate, through experiments and first-principle calculations, that the cation stoichiometry of the nominal LaAlO3 layer is key to 2-DEL formation: only Al-rich LaAlO3 results in a 2-DEL. Although extrinsic defects, including oxygen deficiency, are known to render LaAlO3/SrTiO3 samples conducting, our results show that in the absence of such extrinsic defects an interface 2-DEL can form. Its origin is consistent with an intrinsic electronic reconstruction occurring to counteract a polarization catastrophe. This work provides insight for identifying other interfaces where emergent behaviours await discovery.

  15. Cell-mediated BMP-2 liberation promotes bone formation in a mechanically unstable implant environment.

    Science.gov (United States)

    Hägi, Tobias T; Wu, Gang; Liu, Yuelian; Hunziker, Ernst B

    2010-05-01

    The flexible alloplastic materials that are used in bone-reconstruction surgery lack the mechanical stability that is necessary for sustained bone formation, even if this process is promoted by the application of an osteogenic agent, such as BMP-2. We hypothesize that if BMP-2 is delivered gradually, in a cell-mediated manner, to the surgical site, then the scaffolding material's lack of mechanical stability becomes a matter of indifference. Flexible discs of Ethisorb were functionalized with BMP-2, which was either adsorbed directly onto the material (rapid release kinetics) or incorporated into a calcium-phosphate coating (slow release kinetics). Unstabilized and titanium-plate-stabilized samples were implanted subcutaneously in rats and retrieved up to 14 days later for a histomorphometric analysis of bone and cartilage volumes. On day 14, the bone volume associated with titanium-plate-stabilized discs bearing an adsorbed depot of BMP-2 was 10-fold higher than that associated with their mechanically unstabilized counterparts. The bone volume associated with discs bearing a coating-incorporated depot of BMP-2 was similar in the mechanically unstabilized and titanium-plate-stabilized groups, and comparable to that associated with the titanium-plate-stabilized discs bearing an adsorbed depot of BMP-2. Hence, if an osteogenic agent is delivered in a cell-mediated manner (via coating degradation), ossification can be promoted even within a mechanically unstable environment.

  16. Porous anodic film formation on an Al-3.5 wt % Cu alloy

    Directory of Open Access Journals (Sweden)

    Páez, M. A.

    2003-12-01

    Full Text Available The morphological development of porous anodic films in the initial stages is examined during anodizing an Al-3.5 wt % Cu alloy in phosphoric acid. Using transmission electron microscopy a sequence of ultramicrotomed anodic sections reveals the dynamic evolution of numerous features in the thickening film in the initial stages of anodizing. The morphological changes in the anodic oxide in the initial stages of its formation appears related to the formation of bubbles during film growth. From Rutherford backscattering spectroscopy (RBS analysis of the film, the formation of the bubbles is associated with the enrichment of copper in the alloy due to growth of the anodic oxide. On the other hand, during constant current anodizing of Al-Cu in phosphoric acid, the current efficiency is considerably less than that for anodizing superpure aluminium under similar conditions. From the contrasting results between the charge consumed calculated from RBS and the real charge consumed during anodizing, oxygen gas bubbles generation and copper oxidation seem to be of less importance on the low efficiency for film formation. It is apparent that the main cause of losing efficiency for film growth on Al-Cu is associated with generation of oxygen at residual second phase, with the development of stresses in the film and, the consequence of these effects on film cracking during film growth.

    En este trabajo se examinó el desarrollo morfológico de películas anódicas porosas en los estados iniciales de la anodización de una aleación de aluminio Al-3,5 % p/p Cu. La observación de una secuencia de secciones ultramicrotomadas del metal y su película anódica, por microscopía electrónica de transmisión, revela la evolución dinámica de numerosos detalles morfológicos durante los inicios del crecimiento de la película anódica. Los cambios morfológicos en el óxido anódico, en los inicios de su formación, aparecen relacionados a la formación de

  17. Perilipin1 promotes unilocular lipid droplet formation through the activation of Fsp27 in adipocytes.

    Science.gov (United States)

    Sun, Zhiqi; Gong, Jingyi; Wu, Han; Xu, Wenyi; Wu, Lizhen; Xu, Dijin; Gao, Jinlan; Wu, Jia-Wei; Yang, Hongyuan; Yang, Maojun; Li, Peng

    2013-01-01

    Mature white adipocytes contain a characteristic unilocular lipid droplet. However, the molecular mechanisms underlying unilocular lipid droplet formation are poorly understood. We previously showed that Fsp27, an adipocyte-specific lipid droplet-associated protein, promotes lipid droplet growth by initiating lipid exchange and transfer. Here, we identify Perilipin1 (Plin1), another adipocyte-specific lipid droplet-associated protein, as an Fsp27 activator. Plin1 interacts with the CIDE-N domain of Fsp27 and markedly increases Fsp27-mediated lipid exchange, lipid transfer and lipid droplet growth. Functional cooperation between Plin1 and Fsp27 is required for efficient lipid droplet growth in adipocytes, as depletion of either protein impairs lipid droplet growth. The CIDE-N domain of Fsp27 forms homodimers and disruption of CIDE-N homodimerization abolishes Fsp27-mediated lipid exchange and transfer. Interestingly, Plin1 can restore the activity of CIDE-N homodimerization-defective mutants of Fsp27. We thus uncover a novel mechanism underlying lipid droplet growth and unilocular lipid droplet formation that involves the cooperative action of Fsp27 and Plin1 in adipocytes.

  18. Microglia promote learning-dependent synapse formation through brain-derived neurotrophic factor.

    Science.gov (United States)

    Parkhurst, Christopher N; Yang, Guang; Ninan, Ipe; Savas, Jeffrey N; Yates, John R; Lafaille, Juan J; Hempstead, Barbara L; Littman, Dan R; Gan, Wen-Biao

    2013-12-19

    Microglia are the resident macrophages of the CNS, and their functions have been extensively studied in various brain pathologies. The physiological roles of microglia in brain plasticity and function, however, remain unclear. To address this question, we generated CX3CR1(CreER) mice expressing tamoxifen-inducible Cre recombinase that allow for specific manipulation of gene function in microglia. Using CX3CR1(CreER) to drive diphtheria toxin receptor expression in microglia, we found that microglia could be specifically depleted from the brain upon diphtheria toxin administration. Mice depleted of microglia showed deficits in multiple learning tasks and a significant reduction in motor-learning-dependent synapse formation. Furthermore, Cre-dependent removal of brain-derived neurotrophic factor (BDNF) from microglia largely recapitulated the effects of microglia depletion. Microglial BDNF increases neuronal tropomyosin-related kinase receptor B phosphorylation, a key mediator of synaptic plasticity. Together, our findings reveal that microglia serve important physiological functions in learning and memory by promoting learning-related synapse formation through BDNF signaling.

  19. CDC25B overexpression stabilises centrin 2 and promotes the formation of excess centriolar foci.

    Directory of Open Access Journals (Sweden)

    Rose Boutros

    Full Text Available CDK-cyclin complexes regulate centriole duplication and microtubule nucleation at specific cell cycle stages, although their exact roles in these processes remain unclear. As the activities of CDK-cyclins are themselves positively regulated by CDC25 phosphatases, we investigated the role of centrosomal CDC25B during interphase. We report that overexpression of CDC25B, as is commonly found in human cancer, results in a significant increase in centrin 2 at the centrosomes of interphase cells. Conversely, CDC25B depletion causes a loss of centrin 2 from the centrosome, which can be rescued by treatment with the proteasome inhibitor MG132. CDC25B overexpression also promotes the formation of excess centrin 2 "foci". These foci can accumulate other centrosome proteins, including γ-tubulin and PCM-1, and can function as microtubule organising centres, indicating that these represent functional centrosomes. Formation of centrin 2 foci can be blocked by specific inhibition of CDK2 but not CDK1. CDK2-mediated phosphorylation of Monopolar spindle 1 (Mps1 at the G1/S transition is essential for the initiation of centrosome duplication, and Mps1 is reported to phosphorylate centrin 2. Overexpression of wild-type or non-degradable Mps1 exacerbated the formation of excess centrin 2 foci induced by CDC25B overexpression, while kinase-dead Mps1 has a protective effect. Together, our data suggest that CDC25B, through activation of a centrosomal pool of CDK2, stabilises the local pool of Mps1 which in turn regulates the level of centrin 2 at the centrosome. Overexpression of CDC25B may therefore contribute to tumourigenesis by perturbing the natural turnover of centrosome proteins such as Mps1 and centrin 2, thus resulting in the de novo assembly of extra-numerary centrosomes and potentiating chromosome instability.

  20. Study on the Formation Mechanism of the Solid Siliconized Layer on Ti-48Al Alloy

    Institute of Scientific and Technical Information of China (English)

    MA Xiao-xia; LIANG Wei; ZHAO Xing-guo; SHI Ju-yan; BIAN Li-ping

    2004-01-01

    The microstructures of the siliconized specimens of Ti-48Al alloy were analyzed by SEM equipped with XEDS.The specimens were pack siliconized with the two different cementations, 15%Si+85% Al2O3 and 15%Si+85%ZrO2. The results show that a composite siliconized layer is formed on the surface of the TiAl alloy. The outer layer is the continuous Al2O3 where a lot of Si particles adhered; the inner layer is most of Ti5Si3 with amount of Al2O3 particles dispersed in. It was deduced that the Al2O3 in the cementation layer is formed by the Al atoms in the TiAl substrate react with the residual O in the furnace and in the TiAl substrate.

  1. Spectral evidence of spinodal decomposition, phase transformation and molecular nitrogen formation in supersaturated TiAlN films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Endrino, J.L., E-mail: jlendrino@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, E-28049 Madrid (Spain); Arhammar, C. [Sandvik Tooling AB, R and D, Lerkrogsvaegen 13, 126 80 Stockholm (Sweden); Gutierrez, A. [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales Nicolas Cabrera, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Gago, R. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, E-28049 Madrid (Spain); Horwat, D. [Institut Jean Lamour, Ecole des Mines de Nancy, Parc de Saurupt, 54042 Nancy (France); Soriano, L. [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales Nicolas Cabrera, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Fox-Rabinovich, G. [McMaster University, Hamilton, Ontario, Canada L8S 4L7 (Canada); Martin y Marero, D. [Departamento de Fisica Aplicada and Instituto de Ciencia de Materiales Nicolas Cabrera, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Fundacion Parque Cientifico de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Centro de Microanalisis de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Guo, J. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720 (United States); Rubensson, J.-E. [Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala (Sweden); Andersson, J. [Angstrom Laboratory, Uppsala University, S-75121 Uppsala (Sweden)

    2011-09-15

    Thermal treatment of supersaturated Ti{sub 1-x}Al{sub x}N films (x {approx} 0.67) with a dominant ternary cubic-phase were performed in the 700-1000 {sup o}C range. Grazing incidence X-ray diffraction (GIXRD) shows that, for annealing temperatures up to 800 {sup o}C, the film structure undergoes the formation of coherent cubic AlN (c-AlN) and TiN (c-TiN) nanocrystallites via spinodal decomposition and, at higher temperatures ({>=}900 {sup o}C), GIXRD shows that the c-AlN phase transforms into the thermodynamically more stable hexagonal AlN (h-AlN). X-ray absorption near-edge structure (XANES) at the Ti K-edge is consistent with spinodal decomposition taking place at 800 deg. while Al K-edge and N K-edge XANES and X-ray emission data show the nucleation of the h-AlN phase at temperatures >800 deg. C, in agreement with the two-step decomposition process for rock-salt structured TiAlN, which was also supported by X-ray diffraction patterns and first-principle calculations. Further, the resonant inelastic X-ray scattering technique near the N K-edge revealed that N{sub 2} is formed as a consequence of the phase transformation process.

  2. Formation and surface characterization of nanostructured Al2O3–TiO2 coatings

    Indian Academy of Sciences (India)

    Vairamuthu Raj; Mohamed Sirajudeen Mumjitha

    2014-10-01

    One pot synthesis of Al2O3–TiO2 nanoceramic coatings from environment-friendly potassium titanium oxalate (PTO) electrolyte using facile electrochemical anodization has been reported for the first time. Systematic analysis of the anodization parameters such as applied current density and concentration of the PTO electrolyte influence on the morphology of the ceramic coatings was done. The textural properties of the coatings (thickness, growth rate, coating ratio) showed a linear regime with current density and electrolyte concentration decreases up to a certain level and then decreases. The growth process, distribution of chemical elements, phase constitutions and corrosion resistance of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Tafel polarization technique and electrochemical impedance spectroscopy (EIS). The relation between the corrosion resistivity of the anodic coating and the aforementioned anodization parameters is investigated. The mechanisms that are involved in the formation of the ceramic coatings are also discussed. The coatings formed from 30 g/L concentration of PTO and 0.02 A/cm2 current density show good morphology, textural properties and optimum corrosion resistance.

  3. Formation of porous inner architecture at the interface of magnetic pulse welded Al/Cu joints

    Science.gov (United States)

    Sapanathan, T.; Raoelison, R. N.; Yang, K.; Buiron, N.; Rachik, M.

    2016-10-01

    Porous inner architecture has been revealed at the interface of magnetic pulse welded aluminum/copper (Al/Cu) joints. These materials could serve the purpose of heterogeneous architectured materials, while their makeup of inner architecture of porous interface with the pore sizes of sub-micron to a few microns, could offer potential attributes in energy storage application. Two welding cases with various impact intensities are compared. An input voltage of 6.5 kV with an initial air gap of 1.5 mm and a higher voltage of 7.5 kV with a large initial air gap of 5 mm are respectively considered as two cases with low and high velocity impacts. Overall morphology of the porous medium was revealed at the interface either in layered or pocketed structures. The allocation of the porous zone and pore sizes vary with the impact condition. The low velocity impact welding conditions also produces smaller pores compared to the high velocity impact case, where the pore sizes varies in submicron to a few microns (<10μm). By investigating the potential mechanism of the porous zone formation, it was identified that a combined phenomena of cavitation and coalescence play a major role in nucleation and growth of the pores where a rapid cooling that eventually freezes the porous structure at the interface.

  4. Study on the Formation Mechanism of the Solid Siliconized Layer on Ti-48Al Alloy

    Institute of Scientific and Technical Information of China (English)

    MAXiao-xia; LIANGWei; ZHAOXing-guo; SHIJu-yan; BIANLi-ping

    2004-01-01

    The microstructures of the siliconied specimens of Ti-48Al alloy were analyzed by SEM equipped with XEDS.The specimens were pack siliconized with the two different cementations,15%Si+85% Al2O3 and 15%Si+85%ZrO2.The results show that a composite siliconized layer is formed on the surface of the Tial alloy.The outer layer is the continuous Al2O3 where a lot of Si particles adhered;the inner layer is most of Ti5Si3 with amount of Al2O3 particles dispersed in.It was deduced that the Al2O3 in the cementation layer is formed by the Al atoms in the TiAl substrate react with the residual O in the fumace and in the TiAl substrate.

  5. Polytypic phase formation in DyAl3 by rapid solidification

    Science.gov (United States)

    Xu, Yan; Altounian, Z.; Muir, W. B.

    1991-01-01

    Amorphous ribbons of AlxDy100-x, 93≳x≳85, were obtained by melt spinning. During crystallization, in addition to Al, four different metastable crystalline phases of DyAl3 were observed. These phases are, in order of appearance, the high-pressure face-centered cubic phase, γ-DyAl3 and three polytypic rhombohedral phases, β-DyAl3, β'-DyAl3, and α'-DyAl3. It is the first time that the β' phase in rare-earth trialuminides and the α' phase in Dy-Al alloy system have been observed. It is shown that all these phases are associated with the polytypic packing of the hexagonal DyAl3 atomic layers. The relative stability of the phases is found to be related to the hexagonal to cubic stacking ratio in the structure.

  6. Formation of strained interfaces in AlSb/InAs multilayers grown by molecular beam epitaxy for quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Nicolaï, J.; Warot-Fonrose, B.; Gatel, C., E-mail: christophe.gatel@cemes.fr; Ponchet, A. [CEMES CNRS-UPR 8011, Université de Toulouse, 29 rue Jeanne Marvig, 31055 Toulouse (France); Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS-Universidad de Zaragoza, Toulouse (France); Teissier, R.; Baranov, A. N. [IES CNRS-UMR 5214, 34095 Montpellier (France); Magen, C. [Transpyrenean Associated Laboratory for Electron Microscopy (TALEM), CEMES-INA, CNRS-Universidad de Zaragoza, Toulouse (France); Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA)—ARAID and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain)

    2015-07-21

    Structural and chemical properties of InAs/AlSb interfaces have been studied by transmission electron microscopy. InAs/AlSb multilayers were grown by molecular beam epitaxy with different growth sequences at interfaces. The out-of-plane strain, determined using high resolution microscopy and geometrical phase analysis, has been related to the chemical composition of the interfaces analyzed by high angle annular dark field imaging. Considering the local strain and chemistry, we estimated the interface composition and discussed the mechanisms of interface formation for the different growth sequences. In particular, we found that the formation of the tensile AlAs-type interface is spontaneously favored due to its high thermal stability compared to the InSb-type interface. We also showed that the interface composition could be tuned using an appropriate growth sequence.

  7. Using formative research to develop CHANGE!: a curriculum-based physical activity promoting intervention

    Directory of Open Access Journals (Sweden)

    Knowles Zoe R

    2011-10-01

    Full Text Available Abstract Background Low childhood physical activity levels are currently one of the most pressing public health concerns. Numerous school-based physical activity interventions have been conducted with varied success. Identifying effective child-based physical activity interventions are warranted. The purpose of this formative study was to elicit subjective views of children, their parents, and teachers about physical activity to inform the design of the CHANGE! (Children's Health, Activity, and Nutrition: Get Educated! intervention programme. Methods Semi-structured mixed-gender interviews (group and individual were conducted in 11 primary schools, stratified by socioeconomic status, with 60 children aged 9-10 years (24 boys, 36 girls, 33 parents (4 male, 29 female and 10 teachers (4 male, 6 female. Questions for interviews were structured around the PRECEDE stage of the PRECEDE-PROCEDE model and addressed knowledge, attitudes and beliefs towards physical activity, as well as views on barriers to participation. All data were transcribed verbatim. Pen profiles were constructed from the transcripts in a deductive manner using the Youth Physical Activity Promotion Model framework. The profiles represented analysis outcomes via a diagram of key emergent themes. Results Analyses revealed an understanding of the relationship between physical activity and health, although some children had limited understanding of what constitutes physical activity. Views elicited by children and parents were generally consistent. Fun, enjoyment and social support were important predictors of physical activity participation, though several barriers such as lack of parental support were identified across all group interviews. The perception of family invested time was positively linked to physical activity engagement. Conclusions Families have a powerful and important role in promoting health-enhancing behaviours. Involvement of parents and the whole family is a

  8. EPO promotes bone repair through enhanced cartilaginous callus formation and angiogenesis.

    Directory of Open Access Journals (Sweden)

    Lin Wan

    Full Text Available Erythropoietin (EPO/erythropoietin receptor (EPOR signaling is involved in the development and regeneration of several non-hematopoietic tissues including the skeleton. EPO is identified as a downstream target of the hypoxia inducible factor-α (HIF-α pathway. It is shown that EPO exerts a positive role in bone repair, however, the underlying cellular and molecular mechanisms remain unclear. In the present study we show that EPO and EPOR are expressed in the proliferating, pre-hypertrophic and hypertrophic zone of the developing mouse growth plates as well as in the cartilaginous callus of the healing bone. The proliferation rate of chondrocytes is increased under EPO treatment, while this effect is decreased following siRNA mediated knockdown of EPOR in chondrocytes. EPO treatment increases biosynthesis of proteoglycan, accompanied by up-regulation of chondrogenic marker genes including SOX9, SOX5, SOX6, collagen type 2, and aggrecan. The effects are inhibited by knockdown of EPOR. Blockage of the endogenous EPO in chondrocytes also impaired the chondrogenic differentiation. In addition, EPO promotes metatarsal endothelial sprouting in vitro. This coincides with the in vivo data that local delivery of EPO increases vascularity at the mid-stage of bone healing (day 14. In a mouse femoral fracture model, EPO promotes cartilaginous callus formation at days 7 and 14, and enhances bone healing at day 28 indexed by improved X-ray score and micro-CT analysis of microstructure of new bone regenerates, which results in improved biomechanical properties. Our results indicate that EPO enhances chondrogenic and angiogenic responses during bone repair. EPO's function on chondrocyte proliferation and differentiation is at least partially mediated by its receptor EPOR. EPO may serve as a therapeutic agent to facilitate skeletal regeneration.

  9. Interleukin-8 reduces post-surgical lymphedema formation by promoting lymphatic vessel regeneration.

    Science.gov (United States)

    Choi, Inho; Lee, Yong Suk; Chung, Hee Kyoung; Choi, Dongwon; Ecoiffier, Tatiana; Lee, Ha Neul; Kim, Kyu Eui; Lee, Sunju; Park, Eun Kyung; Maeng, Yong Sun; Kim, Nam Yun; Ladner, Robert D; Petasis, Nicos A; Koh, Chester J; Chen, Lu; Lenz, Heinz-Josef; Hong, Young-Kwon

    2013-01-01

    Lymphedema is mainly caused by lymphatic obstruction and manifested as tissue swelling, often in the arms and legs. Lymphedema is one of the most common post-surgical complications in breast cancer patients and presents a painful and disfiguring chronic illness that has few treatment options. Here, we evaluated the therapeutic potential of interleukin (IL)-8 in lymphatic regeneration independent of its pro-inflammatory activity. We found that IL-8 promoted proliferation, tube formation, and migration of lymphatic endothelial cells (LECs) without activating the VEGF signaling. Additionally, IL-8 suppressed the major cell cycle inhibitor CDKN1C/p57(KIP2) by downregulating its positive regulator PROX1, which is known as the master regulator of LEC-differentiation. Animal-based studies such as matrigel plug and cornea micropocket assays demonstrated potent efficacy of IL-8 in activating lymphangiogenesis in vivo. Moreover, we have generated a novel transgenic mouse model (K14-hIL8) that expresses human IL-8 in the skin and then crossed with lymphatic-specific fluorescent (Prox1-GFP) mouse. The resulting double transgenic mice showed that a stable expression of IL-8 could promote embryonic lymphangiogenesis. Moreover, an immunodeficient IL-8-expressing mouse line that was established by crossing K14-hIL8 mice with athymic nude mice displayed an enhanced tumor-associated lymphangiogenesis. Finally, when experimental lymphedema was introduced, K14-hIL8 mice showed an improved amelioration of lymphedema with an increased lymphatic regeneration. Together, we report that IL-8 can activate lymphangiogenesis in vitro and in vivo with a therapeutic efficacy in post-surgical lymphedema.

  10. EPO promotes bone repair through enhanced cartilaginous callus formation and angiogenesis.

    Science.gov (United States)

    Wan, Lin; Zhang, Fengjie; He, Qiling; Tsang, Wing Pui; Lu, Li; Li, Qingnan; Wu, Zhihong; Qiu, Guixing; Zhou, Guangqian; Wan, Chao

    2014-01-01

    Erythropoietin (EPO)/erythropoietin receptor (EPOR) signaling is involved in the development and regeneration of several non-hematopoietic tissues including the skeleton. EPO is identified as a downstream target of the hypoxia inducible factor-α (HIF-α) pathway. It is shown that EPO exerts a positive role in bone repair, however, the underlying cellular and molecular mechanisms remain unclear. In the present study we show that EPO and EPOR are expressed in the proliferating, pre-hypertrophic and hypertrophic zone of the developing mouse growth plates as well as in the cartilaginous callus of the healing bone. The proliferation rate of chondrocytes is increased under EPO treatment, while this effect is decreased following siRNA mediated knockdown of EPOR in chondrocytes. EPO treatment increases biosynthesis of proteoglycan, accompanied by up-regulation of chondrogenic marker genes including SOX9, SOX5, SOX6, collagen type 2, and aggrecan. The effects are inhibited by knockdown of EPOR. Blockage of the endogenous EPO in chondrocytes also impaired the chondrogenic differentiation. In addition, EPO promotes metatarsal endothelial sprouting in vitro. This coincides with the in vivo data that local delivery of EPO increases vascularity at the mid-stage of bone healing (day 14). In a mouse femoral fracture model, EPO promotes cartilaginous callus formation at days 7 and 14, and enhances bone healing at day 28 indexed by improved X-ray score and micro-CT analysis of microstructure of new bone regenerates, which results in improved biomechanical properties. Our results indicate that EPO enhances chondrogenic and angiogenic responses during bone repair. EPO's function on chondrocyte proliferation and differentiation is at least partially mediated by its receptor EPOR. EPO may serve as a therapeutic agent to facilitate skeletal regeneration.

  11. Formation of Al2O3-HfO2 Eutectic EBC Film on Silicon Carbide Substrate

    Directory of Open Access Journals (Sweden)

    Kyosuke Seya

    2015-01-01

    Full Text Available The formation mechanism of Al2O3-HfO2 eutectic structure, the preparation method, and the formation mechanism of the eutectic EBC layer on the silicon carbide substrate are summarized. Al2O3-HfO2 eutectic EBC film is prepared by optical zone melting method on the silicon carbide substrate. At high temperature, a small amount of silicon carbide decomposed into silicon and carbon. The components of Al2O3 and HfO2 in molten phase also react with the free carbon. The Al2O3 phase reacts with free carbon and vapor species of AlO phase is formed. The composition of the molten phase becomes HfO2 rich from the eutectic composition. HfO2 phase also reacts with the free carbon and HfC phase is formed on the silicon carbide substrate; then a high density intermediate layer is formed. The adhesion between the intermediate layer and the substrate is excellent by an anchor effect. When the solidification process finished before all of HfO2 phase is reduced to HfC phase, HfC-HfO2 functionally graded layer is formed on the silicon carbide substrate and the Al2O3-HfO2 eutectic structure grows from the top of the intermediate layer.

  12. WHI-131 Promotes Osteoblast Differentiation and Prevents Osteoclast Formation and Resorption in Mice.

    Science.gov (United States)

    Cheon, Yoon-Hee; Kim, Ju-Young; Baek, Jong Min; Ahn, Sung-Jun; Jun, Hong Young; Erkhembaatar, Munkhsoyol; Kim, Min Seuk; Lee, Myeung Su; Oh, Jaemin

    2016-02-01

    levels of genes related to osteoblast differentiation, and induced the phosphorylation of Akt, p38, and Smad1/5/8. Furthermore, 5-week-old ICR mice treated with WHI-131 exhibited antiresorbing effects in a lipopolysaccharide-induced calvaria bone loss model in vivo and increased bone-forming activity in a calvarial bone formation model. Therefore, the results of this study show that WHI-131 plays a dual role by inhibiting osteoclast differentiation and promoting osteoblast differentiation. Thus, WHI-131 could be a useful pharmacological agent to treat osteoporosis by promoting bone growth and inhibiting resorption.

  13. Performance improvement of nanocatalysts by promoter-induced defects in the support material: methanol synthesis over Cu/ZnO:Al.

    Science.gov (United States)

    Behrens, Malte; Zander, Stefan; Kurr, Patrick; Jacobsen, Nikolas; Senker, Jürgen; Koch, Gregor; Ressler, Thorsten; Fischer, Richard W; Schlögl, Robert

    2013-04-24

    Addition of small amounts of promoters to solid catalysts can cause pronounced improvement in the catalytic properties. For the complex catalysts employed in industrial processes, the fate and mode of operation of promoters is often not well understood, which hinders a more rational optimization of these important materials. Herein we show for the example of the industrial Cu/ZnO/Al2O3 catalyst for methanol synthesis how structure-performance relationships can deliver such insights and shed light on the role of the Al promoter in this system. We were able to discriminate a structural effect and an electronic promoting effect, identify the relevant Al species as a dopant in ZnO, and determine the optimal Al content of improved Cu/ZnO:Al catalysts. By analogy to Ga- and Cr-promoted samples, we conclude that there is a general effect of promoter-induced defects in ZnO on the metal-support interactions and propose the relevance of this promotion mechanism for other metal/oxide catalysts also.

  14. Moderation of calpain activity promotes neovascular integration and lumen formation during VEGF-induced pathological angiogenesis.

    Directory of Open Access Journals (Sweden)

    Mien V Hoang

    Full Text Available BACKGROUND: Successful neovascularization requires that sprouting endothelial cells (ECs integrate to form new vascular networks. However, architecturally defective, poorly integrated vessels with blind ends are typical of pathological angiogenesis induced by vascular endothelial growth factor-A (VEGF, thereby limiting the utility of VEGF for therapeutic angiogenesis and aggravating ischemia-related pathologies. Here we investigated the possibility that over-exuberant calpain activity is responsible for aberrant VEGF neovessel architecture and integration. Calpains are a family of intracellular calcium-dependent, non-lysosomal cysteine proteases that regulate cellular functions through proteolysis of numerous substrates. METHODOLOGY/PRINCIPAL FINDINGS: In a mouse skin model of VEGF-driven angiogenesis, retroviral transduction with dominant-negative (DN calpain-I promoted neovessel integration and lumen formation, reduced blind ends, and improved vascular perfusion. Moderate doses of calpain inhibitor-I improved VEGF-driven angiogenesis similarly to DN calpain-I. Conversely, retroviral transduction with wild-type (WT calpain-I abolished neovessel integration and lumen formation. In vitro, moderate suppression of calpain activity with DN calpain-I or calpain inhibitor-I increased the microtubule-stabilizing protein tau in endothelial cells (ECs, increased the average length of microtubules, increased actin cable length, and increased the interconnectivity of vascular cords. Conversely, WT calpain-I diminished tau, collapsed microtubules, disrupted actin cables, and inhibited integration of cord networks. Consistent with the critical importance of microtubules for vascular network integration, the microtubule-stabilizing agent taxol supported vascular cord integration whereas microtubule dissolution with nocodazole collapsed cord networks. CONCLUSIONS/SIGNIFICANCE: These findings implicate VEGF-induction of calpain activity and impairment of

  15. TIMP-1 Induces α-Smooth Muscle Actin in Fibroblasts to Promote Urethral Scar Formation

    Directory of Open Access Journals (Sweden)

    Yinglong Sa

    2015-04-01

    Full Text Available Background/Aims: Tissue inhibitor of metalloproteinases-1 (TIMP-1 has been reported to upregulate in urethral scar. However, the underlying molecular mechanisms remain undefined. Methods: Here, we studied levels of TIMP-1 and α-smooth muscle actin (α-SMA in the fibroblasts isolated from urethral scar tissues, compared to the fibroblasts isolated from normal urethra. Then we either overexpressed TIMP-1, or inhibited TIMP-1 by lentiviruses carrying a transgene or a short hairpin small interfering RNA for TIMP-1 in human fibroblasts. We examined the effects of modulation of TIMP-1 on α-SMA, and on epithelial-mesenchymal transition (EMT-related genes. We also studied the underlying mechanisms. Results: We detected significantly higher levels of TIMP-1 and α-smooth muscle actin (α-SMA in the fibroblasts isolated from urethral scar tissues, compared to the fibroblasts isolated from normal urethra. Moreover, the levels of TIMP-1 and α-SMA strongly correlated. Moreover, we found that TIMP-1 significantly increased levels of α-SMA, transforming growth factor β 1 (TGFβ1, Collagen I and some other key factors related to an enhanced EMT, suggesting that TIMP-1 may induce transformation of fibroblasts into myofibroblasts to promote tissue EMT to enhance the formation of urethral scar. Moreover, increases in TIMP-1 also induced an increase in fibroblast cell growth and cell invasion, in an ERK/MAPK-signaling-dependent manner. Conclusion: Our study thus highlights a pivotal role of TIMP-1 in urethral scar formation.

  16. Spp1, a member of the Set1 Complex, promotes meiotic DSB formation in promoters by tethering histone H3K4 methylation sites to chromosome axes.

    Science.gov (United States)

    Sommermeyer, Vérane; Béneut, Claire; Chaplais, Emmanuel; Serrentino, Maria Elisabetta; Borde, Valérie

    2013-01-10

    Meiotic chromosomes are organized into arrays of loops that are anchored to the chromosome axis structure. Programmed DNA double-strand breaks (DSBs) that initiate meiotic recombination, catalyzed by Spo11 and accessory DSB proteins, form in loop sequences in promoters, whereas the DSB proteins are located on chromosome axes. Mechanisms bridging these two chromosomal regions for DSB formation have remained elusive. Here we show that Spp1, a conserved member of the histone H3K4 methyltransferase Set1 complex, is required for normal levels of DSB formation and is associated with chromosome axes during meiosis, where it physically interacts with the Mer2 DSB protein. The PHD finger module of Spp1, which reads H3K4 methylation close to promoters, promotes DSB formation by tethering these regions to chromosome axes and activating cleavage by the DSB proteins. This paper provides the molecular mechanism linking DSB sequences to chromosome axes and explains why H3K4 methylation is important for meiotic recombination.

  17. Energetics of island formation of AlAs, GaAs, and InAs on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Geunjung; Efimov, Oleg; Yoon, Younggui [Chung-Ang University, Seoul (Korea, Republic of)

    2012-03-15

    We study the energetics of island formation of AlAs, GaAs, and InAs on Si(100)2x1 substrates from first-principles. Si(100)2x1:As is stable under As-rich conditions in all cases. Si(100)2x1:(AlAs) and Si(100)2x1:(GaAs) are stable under Al-rich and Ga-rich conditions, respectively. However, the surface energy of Si(100)2x1:InAs is higher than that of Si(100)2x1:As under In-rich conditions. The energies of thicker epitaxial overlayer films of AlAs, GaAs, and InAs are predicted to be higher than the corresponding energies of these monolayer films.

  18. Al-Si alloy point contact formation and rear surface passivation for silicon solar cells using double layer porous silicon

    Science.gov (United States)

    Moumni, Besma; Ben Jaballah, Abdelkader; Bessais, Brahim

    2012-10-01

    Lowering the rear surface recombination velocities by a dielectric layer has fascinating advantages compared with the standard fully covered Al back-contact silicon solar cells. In this work the passivation effect by double layer porous silicon (PS) (wide band gap) and the formation of Al-Si alloy in narrow p-type Si point contact areas for rear passivated solar cells are analysed. As revealed by Fourier transform infrared spectroscopy, we found that a thin passivating aluminum oxide (Al2O3) layer is formed. Scanning electron microscopy analysis performed in cross sections shows that with bilayer PS, liquid Al penetrates into the openings, alloying with the Si substrate at depth and decreasing the contact resistivity. At the solar cell level, the reduction in the contact area and resistivity leads to a minimization of the fill factor losses.

  19. SAMHD1 Inhibits LINE-1 Retrotransposition by Promoting Stress Granule Formation.

    Directory of Open Access Journals (Sweden)

    Siqi Hu

    2015-07-01

    Full Text Available The SAM domain and HD domain containing protein 1 (SAMHD1 inhibits retroviruses, DNA viruses and long interspersed element 1 (LINE-1. Given that in dividing cells, SAMHD1 loses its antiviral function yet still potently restricts LINE-1, we propose that, instead of blocking viral DNA synthesis by virtue of its dNTP triphosphohydrolase activity, SAMHD1 may exploit a different mechanism to control LINE-1. Here, we report a new activity of SAMHD1 in promoting cellular stress granule assembly, which correlates with increased phosphorylation of eIF2α and diminished eIF4A/eIF4G interaction. This function of SAMHD1 enhances sequestration of LINE-1 RNP in stress granules and consequent blockade to LINE-1 retrotransposition. In support of this new mechanism of action, depletion of stress granule marker proteins G3BP1 or TIA1 abrogates stress granule formation and overcomes SAMHD1 inhibition of LINE-1. Together, these data reveal a new mechanism for SAMHD1 to control LINE-1 by activating cellular stress granule pathway.

  20. SAMHD1 Inhibits LINE-1 Retrotransposition by Promoting Stress Granule Formation.

    Science.gov (United States)

    Hu, Siqi; Li, Jian; Xu, Fengwen; Mei, Shan; Le Duff, Yann; Yin, Lijuan; Pang, Xiaojing; Cen, Shan; Jin, Qi; Liang, Chen; Guo, Fei

    2015-07-01

    The SAM domain and HD domain containing protein 1 (SAMHD1) inhibits retroviruses, DNA viruses and long interspersed element 1 (LINE-1). Given that in dividing cells, SAMHD1 loses its antiviral function yet still potently restricts LINE-1, we propose that, instead of blocking viral DNA synthesis by virtue of its dNTP triphosphohydrolase activity, SAMHD1 may exploit a different mechanism to control LINE-1. Here, we report a new activity of SAMHD1 in promoting cellular stress granule assembly, which correlates with increased phosphorylation of eIF2α and diminished eIF4A/eIF4G interaction. This function of SAMHD1 enhances sequestration of LINE-1 RNP in stress granules and consequent blockade to LINE-1 retrotransposition. In support of this new mechanism of action, depletion of stress granule marker proteins G3BP1 or TIA1 abrogates stress granule formation and overcomes SAMHD1 inhibition of LINE-1. Together, these data reveal a new mechanism for SAMHD1 to control LINE-1 by activating cellular stress granule pathway.

  1. Soybean NAC transcription factors promote abiotic stress tolerance and lateral root formation in transgenic plants.

    Science.gov (United States)

    Hao, Yu-Jun; Wei, Wei; Song, Qing-Xin; Chen, Hao-Wei; Zhang, Yu-Qin; Wang, Fang; Zou, Hong-Feng; Lei, Gang; Tian, Ai-Guo; Zhang, Wan-Ke; Ma, Biao; Zhang, Jin-Song; Chen, Shou-Yi

    2011-10-01

    NAC transcription factors play important roles in plant growth, development and stress responses. Previously, we identified multiple NAC genes in soybean (Glycine max). Here, we identify the roles of two genes, GmNAC11 and GmNAC20, in stress responses and other processes. The two genes were differentially induced by multiple abiotic stresses and plant hormones, and their transcripts were abundant in roots and cotyledons. Both genes encoded proteins that localized to the nucleus and bound to the core DNA sequence CGT[G/A]. In the protoplast assay system, GmNAC11 acts as a transcriptional activator, whereas GmNAC20 functions as a mild repressor; however, the C-terminal end of GmANC20 has transcriptional activation activity. Over-expression of GmNAC20 enhances salt and freezing tolerance in transgenic Arabidopsis plants; however, GmNAC11 over-expression only improves salt tolerance. Over-expression of GmNAC20 also promotes lateral root formation. GmNAC20 may regulate stress tolerance through activation of the DREB/CBF-COR pathway, and may control lateral root development by altering auxin signaling-related genes. GmNAC11 probably regulates DREB1A and other stress-related genes. The roles of the two GmNAC genes in stress tolerance were further analyzed in soybean transgenic hairy roots. These results provide a basis for genetic manipulation to improve the agronomic traits of important crops.

  2. Epithelial membrane protein-2 promotes endometrial tumor formation through activation of FAK and Src.

    Directory of Open Access Journals (Sweden)

    Maoyong Fu

    Full Text Available Endometrial cancer is the most common gynecologic malignancy diagnosed among women in developed countries. One recent biomarker strongly associated with disease progression and survival is epithelial membrane protein-2 (EMP2, a tetraspan protein known to associate with and modify surface expression of certain integrin isoforms. In this study, we show using a xenograft model system that EMP2 expression is necessary for efficient endometrial tumor formation, and we have started to characterize the mechanism by which EMP2 contributes to this malignant phenotype. In endometrial cancer cells, the focal adhesion kinase (FAK/Src pathway appears to regulate migration as measured through wound healing assays. Manipulation of EMP2 levels in endometrial cancer cells regulates the phosphorylation of FAK and Src, and promotes their distribution into lipid raft domains. Notably, cells with low levels of EMP2 fail to migrate and poorly form tumors in vivo. These findings reveal the pivotal role of EMP2 in endometrial cancer carcinogenesis, and suggest that the association of elevated EMP2 levels with endometrial cancer prognosis may be causally linked to its effect on integrin-mediated signaling.

  3. Removal of Phosphorus in Silicon by the Formation of CaAl2Si2 Phase at the Solidification Interface

    Science.gov (United States)

    Sun, Liyuan; Wang, Zhi; Chen, Hang; Wang, Dong; Qian, Guoyu

    2017-02-01

    To fully understand the role of CaAl2Si2 phase in concentrating the non-metallic impurity phosphorus, an experiment of directional solidification of Al-70 at. pct Si alloy with extreme small lowering rate 0.05 mm min-1 was carried out. With good dynamic condition for the diffusion of impurity (Ca, Al, P) from silicon to the S/L interface, the CaAl2Si2 phase with 0.6-0.7 at. pct P was successfully observed by Electron Probe Micro Analyzer (EPMA), and its distribution character was originally presented. This impurity phase was widely detected in the refined sample but only at the interface of silicon crystal and Al-Si alloy which contributed to the deep removal of impurity P. The formation mechanism of CaAl2Si2-P phase was thus explored, in which the microsegregation and concentration of element P, Ca, Al in front of S/L interface were crucial. After acid leaching, the P content decreased from the original 23 ppm to below 5 ppm. Compared with normal solidification, a 16 pct higher removal efficiency of P was obtained in this study.

  4. Formation of nanocrystalline h-AlN during mechanochemical decomposition of melamine in the presence of metallic aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Rounaghi, S.A., E-mail: s.a.rounaghi@gmail.com [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of); Kiani Rashid, A.R. [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of); Eshghi, H., E-mail: heshghi@ferdowsi.um.ac.ir [Department of Chemistry, Ferdowsi University of Mashhad, P.O. Box No. 91775-1436, Mashhad (Iran, Islamic Republic of); Vahdati Khaki, J. [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of)

    2012-06-15

    Decomposition of melamine was studied by solid state reaction of melamine and aluminum powders during high energy ball-milling. The milling procedure performed for both pure melamine and melamine/Al mixed powders as the starting materials for various times up to 48 h under ambient atmosphere. The products were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results revealed that Al causes melamine deammoniation at the first stages of milling and further milling process leads to the s-triazine ring degradation while nano-crystallite hexagonal aluminum nitride (h-AlN) was the main solid product. Comparison to milling process, the possibility of the reaction of melamine with Al was also investigated by thermal treatment method using differential scanning calorimeter (DSC) and thermo gravimetric analyzer (TGA). Melamine decomposition occurred by thermal treatment in the range of 270-370 Degree-Sign C, but no reaction between melamine and aluminum was observed. - Graphical Abstract: Mechanochemical reaction of melamine with Al resulted in the formation of nanocrystalline AlN after 7 h milling time Highlights: Black-Right-Pointing-Pointer High energy ball milling of melamine and aluminum results decomposition of melamine with elimination of ammonia. Black-Right-Pointing-Pointer Nano-crystalline AlN was synthesized by the mechanochemical route. Black-Right-Pointing-Pointer Milling process has no conspicuous effect on pure melamine degradation. Black-Right-Pointing-Pointer No reaction takes place by heating melamine and aluminum powder mixture in argon.

  5. Polytypic phase formation in DyAl sub 3 by rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y.; Altounian, Z.; Muir, W.B. (Centre for the Physics of Materials and the Department of Physics, McGill University, 3600 University Street, Montreal, Quebec H3A 2T8, Canada (CA))

    1991-01-14

    Amorphous ribbons of Al{sub {ital x}}Dy{sub 100{minus}{ital x}}, 93{gt}{ital x}{gt}85, were obtained by melt spinning. During crystallization, in addition to Al, four different metastable crystalline phases of DyAl{sub 3} were observed. These phases are, in order of appearance, the high-pressure face-centered cubic phase, {gamma}-DyAl{sub 3} and three polytypic rhombohedral phases, {beta}-DyAl{sub 3}, {beta}{prime}-DyAl{sub 3}, and {alpha}{prime}-DyAl{sub 3}. It is the first time that the {beta}{prime} phase in rare-earth trialuminides and the {alpha}{prime} phase in Dy-Al alloy system have been observed. It is shown that all these phases are associated with the polytypic packing of the hexagonal DyAl{sub 3} atomic layers. The relative stability of the phases is found to be related to the hexagonal to cubic stacking ratio in the structure.

  6. Effect of Pt promotion on Ni/Al2O3 for the selective catalytic reduction of NO with hydrogen

    Science.gov (United States)

    Mihet, Maria; Lazar, Mihaela D.; Borodi, G.; Almasan, V.

    2013-11-01

    Ni/Al2O3 (10 wt.% Ni) and Ni-Pt/Al2O3 (10 wt.% Ni, 0.5 wt.% Pt) were comparatively tested in the hydrogen selective catalytic reduction process (H2-SCR), at reaction temperatures below 350°C. Catalytic activity tests consisted in temperature programmed reactions (TPRea) under plug flow conditions from 50 to 350°C, with a temperature rate of 5°C/min, using a feed stream with a reactant ratio NO:H2 = 1:1.3 and a GHSV of 4500 h-1. Promotion with Pt increases the catalytic performances of the Ni based catalyst, in respect to NO conversion, N2 selectivity and N2 yield. The reaction temperatures for NO conversion above 95% decrease significantly due to Pt addition, from 250°C for Ni/Al2O3 to 125°C for Ni-Pt/Al2O3. Characterization of catalysts was performed by: X ray powder diffraction (XRD) for the estimation of Ni crystallite size, temperature programmed reduction (TPR) for the catalyst reducibility, temperature programmed desorption of hydrogen (H2-TPD) for the investigation of active sites and metal dispersion on the support, N2 adsorption-desorption isotherms at -196°C for the determination of total specific surface area and pore size distribution, and H/D isotopic exchange on the catalyst surface. At the request of the Proceedings Editor, and all authors of the paper, an updated version of this article was published on 14 January 2014. Data presented in Table 1 of the original paper contained errors which have been corrected in the updated and re-published article. The Corrigendum attached to the corrected article PDF file explains the errors in more detail.

  7. Formation Mechanisms of Alloying Element Nitrides in Recrystallized and Deformed Ferritic Fe-Cr-Al Alloy

    Science.gov (United States)

    Akhlaghi, Maryam; Meka, Sai Ramudu; Jägle, Eric A.; Kurz, Silke J. B.; Bischoff, Ewald; Mittemeijer, Eric J.

    2016-09-01

    The effect of the initial microstructure (recrystallized or cold-rolled) on the nitride precipitation process upon gaseous nitriding of ternary Fe-4.3 at. pct Cr-8.1 at. pct Al alloy was investigated at 723 K (450 °C) employing X-ray diffraction (XRD) analyses, transmission electron microscopy (TEM), atom probe tomography (APT), and electron probe microanalysis (EPMA). In recrystallized Fe-Cr-Al specimens, one type of nitride develops: ternary, cubic, NaCl-type mixed Cr1- x Al x N. In cold-rolled Fe-Cr-Al specimens, precipitation of two types of nitrides occurs: ternary, cubic, NaCl-type mixed Cr1- x Al x N and binary, cubic, NaCl-type AlN. By theoretical analysis, it was shown that for the recrystallized specimens an energy barrier for the nucleation of mixed Cr1- x Al x N exists, whereas in the cold-rolled specimens no such energy barriers for the development of mixed Cr1- x Al x N and of binary, cubic AlN occur. The additional development of the cubic AlN in the cold-rolled microstructure could be ascribed to the preferred heterogeneous nucleation of cubic AlN on dislocations. The nitrogen concentration-depth profile of the cold-rolled specimen shows a stepped nature upon prolonged nitriding as a consequence of instantaneous nucleation of nitride upon arrival of nitrogen and nitride growth rate-limited by nitrogen transport through the thickening nitrided zone.

  8. EPFR Formation from Phenol adsorption on Al2O3 and TiO2: EPR and EELS studies

    Science.gov (United States)

    Patterson, Matthew C.; Keilbart, Nathan D.; Kiruri, Lucy W.; Thibodeaux, Chad A.; Lomnicki, Slawo; Kurtz, Richard L.; Poliakoff, E. D.; Dellinger, Barry; Sprunger, Phillip T.

    2013-01-01

    We have examined the formation of environmentally persistent free radicals (EPFRs) from phenol over alumina and titania using both powder and single-crystal samples. Electron paramagnetic resonance (EPR) studies of phenol adsorbed on metal oxide powders indicates radical formation on both titania and alumina, with both oxides forming one faster-decaying species (lifetime on the order of 50-100 hours) and one slower-decayng species (lifetimes on the order of 1000 hours or more). Electron energy loss spectroscopy (EELS) measurements comparing physisorbed phenol on single-crystal TiO2(110) to phenoxyl radicals on the same substrate indicate distinct changes in the π-π* transitions from phenol after radical formation. The identical shifts are observed from EELS studies of phenoxyl radicals on ultrathin alumina grown on NiAl(110), indicating that this shift in the π-π* transition may be taken as a general hallmark of phenoxyl radical formation. PMID:24443627

  9. Li overlayer formation, oxidation and sputtering characteristics of Al-Li alloys and W/Al-Li composites for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, A.R. (Argonne National Lab., IL (USA)); DeWald, A.B.; Scott, P.; Savage, H. (Corium Industries, Inc., Atlanta, GA (USA))

    1990-01-01

    The next generation of long pulse fusion devices will impose severe requirements on the properties of plasma-facing materials. In devices such as ITER, a divertor design is being considered, using a divertor plate which would be either tungsten or a low-Z material such as graphite or beryllium. Strongly segregating lithium alloys have been proposed as a means of producing a self-sustaining low-Z overlayer which lowers plasma Z{sub eff} and resists self-sputtering. Aluminum-lithium alloys are among the better-characterized lithium-bearing alloys, and it has been demonstrated that lithium segregates strongly in aluminum. However, aluminum has a relatively low melting point, and for low lithium concentrations, the lithium diffusion rate is too slow to replenish lithium at the rate at which it is eroded by the incoming plasma. It has been suggested previously that the superionic {beta} phase Al-Li alloy (48--54 at. % Li) should have high enough diffusivity to be able to replenish surface lithium, and that incorporation of the {beta}-phase AlLi in a composite with tungsten would provide high temperature strength and melt layer stability, along with significantly better thermal conductivity than pure tungsten. Such a composite has been fabricated, as well as a variation containing titanium as a means of controlling oxidation at grain boundaries. The Li overlayer formation, erosion, and replenishment are characterized for the {beta}-phase LiAl alloy, and W-AlLi and W-Ti-AlLi composites. It is found that if there is no oxide layer to inhibit the Li segregation, Li diffusion is extremely rapid, and an oxygen-free Li overlayer is formed which is stable under continuous ion beam sputtering. 21 refs., 7 figs.

  10. GABA agonist promoted formation of low affinity GABA receptors on cerebellar granule cells is restricted to early development

    DEFF Research Database (Denmark)

    Belhage, B; Hansen, G H; Schousboe, A;

    1988-01-01

    The ability of the GABA receptor agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP) to promote formation of low affinity GABA receptors on cerebellar granule cells was tested using primary cultures of these neurons. Granule cells were exposed to THIP (150 microM) for 6 hr after......, respectively, 4, 7, 10 and 14 days in culture. It was found that THIP treatment of 4- and 7-day-old cultures led to formation of low affinity GABA receptors, whereas such receptors could not be detected after THIP treatment in the older cultures (10 and 14 days) in spite of the fact that these cultured granule...... cells expressed a high density of high affinity GABA receptors. It is concluded that the ability of THIP to promote formation of low affinity GABA receptors on cerebellar granule cells is restricted to an early developmental period....

  11. Formation and characteristics of AlGaN-based three-dimensional hexagonal nanopyramid semi-polar multiple quantum wells

    Science.gov (United States)

    Tian, Yingdong; Yan, Jianchang; Zhang, Yun; Zhang, Yonghui; Chen, Xiang; Guo, Yanan; Wang, Junxi; Li, Jinmin

    2016-05-01

    We demonstrated for the first time the formation and study of semi-polar AlGaN multiple-quantum-wells (MQWs) grown on highly regular hexagonal AlN nanopyramids. The AlN nanopyramids were obtained by a metal-organic chemical vapor phase deposition regrowth method on a well-ordered AlN nanorod array prepared by a top-down etching process. The growth mechanism of the AlN nanopyramids was ascribed to the slow growth of the (101&cmb.macr;1) semi-polar plane, which resulted from hydrogen passivation. Beneath the semi-polar facets, air voids were formed. This was attributed to the insufficient delivery of gas reactants to the bottom of the nanorods during the growth process. The polarization effect in semi-polar AlGaN MQWs was numerically calculated. The results showed that the internal electric field (IEF) in the semi-polar MQWs was remarkably reduced by 80% in comparison with c-plane MQWs. Power dependent photoluminescence indicated that the semi-polar AlGaN MQWs had negligible wavelength shifts that resulted from the reduced IEF, which was in accordance with theoretical predictions. In addition, epitaxial strain was greatly relieved in the AlN regrowth layer, which was revealed from the peak shift of the E2(high) phonon using micro-Raman spectroscopy. The advantages of AlGaN-based hexagonal nanopyramid semi-polar three dimensional nanostructures would lead to a large improvement of output power in UV-LEDs.

  12. Intact fetal ovarian cord formation promotes mouse oocyte survival and development

    Directory of Open Access Journals (Sweden)

    Pera Renee

    2010-01-01

    Full Text Available Abstract Background Female reproductive potential, or the ability to propagate life, is limited in mammals with the majority of oocytes lost before birth. In mice, surviving perinatal oocytes are enclosed in ovarian follicles for subsequent oocyte development and function in the adult. Before birth, fetal germ cells of both sexes develop in clusters, or germline cysts, in the undifferentiated gonad. Upon sex determination of the fetal gonad, germ cell cysts become organized into testicular or ovarian cord-like structures and begin to interact with gonadal somatic cells. Although germline cysts and testicular cords are required for spermatogenesis, the role of cyst and ovarian cord formation in mammalian oocyte development and female fertility has not been determined. Results Here, we examine whether intact fetal ovarian germ and somatic cell cord structures are required for oocyte development using mouse gonad re-aggregation and transplantation to disrupt gonadal organization. We observed that germ cells from disrupted female gonad prior to embryonic day e13.5 completed prophase I of meiosis but did not survive following transplantation. Furthermore, re-aggregated ovaries from e13.5 to e15.5 developed with a reduced number of oocytes. Oocyte loss occurred before follicle formation and was associated with an absence of ovarian cord structure and ovary disorganization. However, disrupted ovaries from e16.5 or later were resistant to the re-aggregation impairment and supported robust oocyte survival and development in follicles. Conclusions Thus, we demonstrate a critical window of oocyte development from e13.5 to e16.5 in the intact fetal mouse ovary, corresponding to the establishment of ovarian cord structure, which promotes oocyte interaction with neighboring ovarian somatic granulosa cells before birth and imparts oocytes with competence to survive and develop in follicles. Because germline cyst and ovarian cord structures are conserved in the

  13. Formation of Al3Ti/Mg composite by powder metallurgy of Mg–Al–Ti system

    Directory of Open Access Journals (Sweden)

    Zi R Yang et al

    2008-01-01

    Full Text Available An in situ titanium trialuminide (Al3Ti-particle-reinforced magnesium matrix composite has been successfully fabricated by the powder metallurgy of a Mg–Al–Ti system. The reaction processes and formation mechanism for synthesizing the composite were studied by differential scanning calorimetry (DSC, x-ray diffractometry (XRD, scanning electron microscopy (SEM and energy-dispersive x-ray spectroscopy (EDS. Al3Ti particles are found to be synthesized in situ in the Mg alloy matrix. During the reaction sintering of the Mg–Al–Ti system, Al3Ti particles are formed through the reaction of liquid Al with as-dissolved Ti around the Ti particles. The formed intermetallic particles accumulate at the original sites of the Ti particles. As sintering time increases, the accumulated intermetallic particles disperse and reach a relatively homogeneous distribution in the matrix. It is found that the reaction process of the Mg–Al–Ti system is almost the same as that of the Al–Ti system. Mg also acts as a catalytic agent and a diluent in the reactions and shifts the reactions of Al and Ti to lower temperatures. An additional amount of Al is required for eliminating residual Ti and solid-solution strengthening of the Mg matrix.

  14. Formation of ordered CoAl alloy clusters by the plasma-gas condensation technique

    OpenAIRE

    Toyohiko J., Konno; Saeki, Yamamuro; Kenji, Sumiyama

    2001-01-01

    CoxAl1-x alloy clusters were synthesized from a mixture of Co and Al metal vapors generated by the sputtering of pure metal targets. We observed that the produced alloy clusters were uniform in size, ranging from approximately 20 nm for Al-rich clusters to 10 nm for Co-rich clusters. For a wide average composition range (x?0.4-0.7), the alloy clusters have the ordered B2 (CsCl-type) structure. In the Co-rich cluster aggregates (x=0.76), the clusters are composed of face-centered-cubic (fcc) C...

  15. Mechanism of pore formation and structural characterization for mesoporous Mg-Al composite oxides

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Mg-Al layered double hydroxides(LDH) with different particle sizes were prepared using different aging times at high supersaturation by a new method developed in our laboratory. The key features of this method are a very rapid mixing and nucleation process followed by a separate aging process. By calcination of LDH at 500℃, mesoporous Mg-Al composite oxides with an ex-tremely narrow pore size distribution were produced. The crystal structure of the Mg-Al composite oxides was a multiphasic one consisting of MgO-like crystals and a layered material.

  16. STM-Induced Void Formation at the Al{sub 2}O{sub 3}/Ni{sub 3}Al(111) Interface

    Energy Technology Data Exchange (ETDEWEB)

    Magtoto, N.P.; Niu, C.; Anzaldura, M.; Kelber, J.A.; Jennison, D.R.

    2000-09-21

    Under UHV conditions at 300 K, the applied electric field and/or resulting current from an STM tip creates nanoscale voids at the interface between an epitaxial, 7.0 {angstrom} thick Al{sub 2}O{sub 3} film and a Ni{sub 3}Al(111) substrate. This phenomenon is independent of tip polarity. Constant current (1 nA) images obtained at +0.1 V bias and +2.0 bias voltage (sample positive) reveal that voids are within the metal at the interface and, when small, are capped by the oxide film. Void size increases with time of exposure. The rate of void growth increases with applied bias/field and tunneling current, and increases significantly for field strengths >5 MV/cm, well below the dielectric breakdown threshold of 12 {+-} 1 MV/cm. Slower rates of void growth are, however, observed at lower applied field strengths. Continued growth of voids, to {approximately}30 {angstrom} deep and {approximately}500 {angstrom} wide, leads to the eventual failure of the oxide overlayer. Density Functional Theory calculations suggest a reduction-oxidation (REDOX) mechanism: interracial metal atoms are oxidized via transport into the oxide, while oxide surface Al cations are reduced to admetal species which rapidly diffuse away. This is found to be exothermic in model calculations, regardless of the details of the oxide film structure; thus, the barriers to void formation are kinetic rather than thermodynamic. We discuss our results in terms of mechanisms for the localized pitting corrosion of aluminum, as our results suggest nanovoid formation requires just electric field and current, which are ubiquitous in environmental conditions.

  17. Formation of Aluminum Containing Solids in Drinking Water: Influence on Pb/Cu Corrosion, Al Solubility and Enhanced Softening

    OpenAIRE

    Kvech, Steven Joseph

    2001-01-01

    Aluminum salts are used as the primary coagulants in the majority of United States drinking water treatment plants. Despite decades of practical experience, there are important knowledge gaps regarding the effects of residual Al on distribution system materials as well as specific types of solids formed. The first phase of this work examined the formation of aluminosilicate deposits in copper and lead pipes using water from Denver, Colorado. It was anticipated was that these de...

  18. Formation and dissolution kinetics of Al(OH)3 (s) in synthetic freshwater solutions

    Science.gov (United States)

    Lydersen, E.; Salbu, B.; PolèO, A. B. S.; Muniz, I. P.

    1991-03-01

    The precipitation of Al in aqueous solutions can be described as a two-step process. When acidic inorganic Al solutions (pH 4.5) were titrated with NaOH to pH levels between 5.5 and 6.0, an amorphous Al(OH)3 (s) phase was formed instantaneously. During the first 5 min, the apparent half time for the reduction in dissolved Al species (t1/2) was 0.162 ± 0.07 hours (n = 4). The decrease of dissolved Al species continued during the following 24 hours, but at a far slower rate (t1/2 = 55.6 ± 25 hours (n = 4)). The highest precipitation rates were found in the solution of highest pH, and at approximately identical pH, the highest rate was found in the solution of highest temperature. The dissolution of amorphous Al(OH)3 (s) can also be described as a two-step process. When the amorphous Al solutions (pH between 5.5 and 6.0) were acidified to pH about 4.5 (HCl), the initial dissolution was relatively fast, but not as instantaneous as in the first step of precipitation. The apparent t1/2 after 5 min was estimated to be 0.65 ± 0.12 hours (n = 4). During the first 2.67 hours (160 min) the dissolution step could be described by the equation C(t) = C0e-0.45t, i.e., t1/2 = 1.53 ± 0.60 hours (n = 20) according to which the solid Al phase should dissolve totally (97%) during 7.65 hours. However, after 24 hours of storage 40 to 50% of the original Al(OH)3 (s) remained in the solid phase. This is explained by the presence of a far lower dissolution rate in a second step, i.e., the remaining Al(OH)3 (s) was less soluble. The average dissolution rate for the rest of the 24-hour period (21.33 hours) could be described by the exponential function C(t) = C0e-0.0095t, i.e., t1/2 = 73.2 ± 23.4 hours (n = 4). This implies that a total dissolution of Al (97%) will occur after 15.3 ± 4.9 days. The implications of these findings are discussed with reference to the current geochemical models pretending to simulate and predict aluminum chemistry in soils and surface runoff.

  19. Influence of Aluminum on the Formation Behavior of Zn-Al-Fe Intermetallic Particles in a Zinc Bath

    Science.gov (United States)

    Park, Joo Hyun; Park, Geun-Ho; Paik, Doo-Jin; Huh, Yoon; Hong, Moon-Hi

    2012-01-01

    The shape, size, and composition of dross particles as a function of aluminum content at a fixed temperature were investigated for aluminum added to the premelted Zn-Fe melt simulating the hot-dip galvanizing bath by a sampling methodology. In the early stage, less than 30 minutes after Al addition, local supersaturation and depletion of the aluminum concentration occurred simultaneously in the bath, resulting in the nucleation and growth of both Fe2Al5Zn x and FeZn13. However, the aluminum was homogenized continuously as the reaction proceeded, and fine and stable FeZn10Al x formed after 30 minutes. An Al-depleted zone (ADZ) mechanism was newly proposed for the "η→η+ζ→δ" phase transformations. The ζ phase bottom dross partly survived for a relatively long period, i.e., 2 hours in this work, whereas the η phase disappeared after 30 minutes. In the early stage of dross formation, both Al-free large particles as well as high-Al tiny particles were formed. The dross particle size decreased slightly with increased reaction time before reaching a plateau. The opposite tendency was observed when the Al content was 0.130 mass pct; with a relatively high Al content, the nucleation of tiny η phase dross was significantly enhanced because of the high degree of supersaturation. This unstable η phase dissolved continuously and underwent simple transformation to the stable δ phase. The relationship between nucleation potential and supersaturation ratio of species is discussed based on the thermodynamics of classical nucleation theory.

  20. Characterization of Industrial Pt-Sn/Al2O3 Catalyst and Transient Product Formations during Propane Dehydrogenation

    Directory of Open Access Journals (Sweden)

    Kah Sing Ho

    2013-06-01

    Full Text Available The major problem plaguing propane dehydrogenation process is the coke formation on the Pt-Sn/Al2O3 catalyst which leads to catalyst deactivation. Due to information paucity, the physicochemical characteristics of the commercially obtained regenerated Pt-Sn/Al2O3 catalyst (operated in moving bed reactor and coke formation at different temperatures of reaction were discussed. The physicochemical characterization of regenerated catalyst gave a BET surface area of 104.0 m2/g with graphitic carbon content of 8.0% indicative of incomplete carbon gasification during the industrial propylene production. Effect of temperatures on coke formation was identified by studying the product yield via temperature-programmed reaction carried out at 500oC, 600oC and 700oC. It was found that ethylene was precursor to carbon laydown while propylene tends to crack into methane. Post reaction, the spent catalyst possessed relatively lower surface area and pore radius whilst exhibited higher carbon content (31.80% at 700oC compared to the regenerated catalyst. Significantly, current studies also found that higher reaction temperatures favoured the coke formation. Consequently, the propylene yield has decreased with reaction temperature. © 2013 BCREC UNDIP. All rights reservedReceived: 10th March 2013; Revised: 28th April 2013; Accepted: 6th May 2013[How to Cite: Kah, S.H., Joanna Jo, E.C., Sim, Y.C., Chin, K.C. (2013. Characterization of Industrial Pt-Sn/Al2O3 Catalyst and Transient Product Formations during Propane Dehydrogenation. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 77-82. (doi:10.9767/bcrec.8.1.4569.77-82][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4569.77-82] | View in  |

  1. Aggregation of ALS-linked FUS mutant sequesters RNA binding proteins and impairs RNA granules formation

    Energy Technology Data Exchange (ETDEWEB)

    Takanashi, Keisuke; Yamaguchi, Atsushi, E-mail: atsyama@restaff.chiba-u.jp

    2014-09-26

    Highlights: • Aggregation of ALS-linked FUS mutant sequesters ALS-associated RNA-binding proteins (FUS wt, hnRNP A1, and hnRNP A2). • Aggregation of ALS-linked FUS mutant sequesters SMN1 in the detergent-insoluble fraction. • Aggregation of ALS-linked FUS mutant reduced the number of speckles in the nucleus. • Overproduced ALS-linked FUS mutant reduced the number of processing-bodies (PBs). - Abstract: Protein aggregate/inclusion is one of hallmarks for neurodegenerative disorders including amyotrophic lateral sclerosis (ALS). FUS/TLS, one of causative genes for familial ALS, encodes a multifunctional DNA/RNA binding protein predominantly localized in the nucleus. C-terminal mutations in FUS/TLS cause the retention and the inclusion of FUS/TLS mutants in the cytoplasm. In the present study, we examined the effects of ALS-linked FUS mutants on ALS-associated RNA binding proteins and RNA granules. FUS C-terminal mutants were diffusely mislocalized in the cytoplasm as small granules in transiently transfected SH-SY5Y cells, whereas large aggregates were spontaneously formed in ∼10% of those cells. hnRNP A1, hnRNP A2, and SMN1 as well as FUS wild type were assembled into stress granules under stress conditions, and these were also recruited to FUS mutant-derived spontaneous aggregates in the cytoplasm. These aggregates stalled poly(A) mRNAs and sequestered SMN1 in the detergent insoluble fraction, which also reduced the number of nuclear oligo(dT)-positive foci (speckles) in FISH (fluorescence in situ hybridization) assay. In addition, the number of P-bodies was decreased in cells harboring cytoplasmic granules of FUS P525L. These findings raise the possibility that ALS-linked C-terminal FUS mutants could sequester a variety of RNA binding proteins and mRNAs in the cytoplasmic aggregates, which could disrupt various aspects of RNA equilibrium and biogenesis.

  2. Quantitative Analyses of Force-Induced Amyloid Formation in Candida albicans Als5p: Activation by Standard Laboratory Procedures.

    Directory of Open Access Journals (Sweden)

    Cho X J Chan

    Full Text Available Candida albicans adhesins have amyloid-forming sequences. In Als5p, these amyloid sequences cluster cell surface adhesins to create high avidity surface adhesion nanodomains. Such nanodomains form after force is applied to the cell surface by atomic force microscopy or laminar flow. Here we report centrifuging and resuspending S. cerevisiae cells expressing Als5p led to 1.7-fold increase in initial rate of adhesion to ligand coated beads. Furthermore, mechanical stress from vortex-mixing of Als5p cells or C. albicans cells also induced additional formation of amyloid nanodomains and consequent activation of adhesion. Vortex-mixing for 60 seconds increased the initial rate of adhesion 1.6-fold. The effects of vortex-mixing were replicated in heat-killed cells as well. Activation was accompanied by increases in thioflavin T cell surface fluorescence measured by flow cytometry or by confocal microscopy. There was no adhesion activation in cells expressing amyloid-impaired Als5pV326N or in cells incubated with inhibitory concentrations of anti-amyloid dyes. Together these results demonstrated the activation of cell surface amyloid nanodomains in yeast expressing Als adhesins, and further delineate the forces that can activate adhesion in vivo. Consequently there is quantitative support for the hypothesis that amyloid forming adhesins act as both force sensors and effectors.

  3. Lanthanum oxide promoted rhodium/titania and rhodium-platinum/titania catalysts for alcohol formation from synthesis gas

    Energy Technology Data Exchange (ETDEWEB)

    Bond, G.C.; Richards, D.G.

    1986-12-15

    TiO/sub 2/-supported Rh and Rh-Pt catalysts have been studied for the selective formation of oxygenates from synthesis gas. The addition of La/sub 2/O/sub 3/ as a promoter significantly increased the C/sub 2/H/sub 5/OH selectivities and formation rates. Pt addition increased the overall activity and in combination with La/sub 2/O/sub 3/ led to higher alcohol selectivities of 25% compared with 6% for an unpromoted Rh catalyst. A pronounced induction period was observed for CH/sub 3/OH and C/sub 2/H/sub 5/OH formation, attributed to changes in the nature of the catalytically active sites. A simple theoretical model is used to illustrate the parallel trends in C/sub 2/H/sub 5/OH and hydrocarbon formation after the induction period. Temperature-programmed reduction showed that the La/sub 2/O/sub 3/ increased the stability of Rh oxide. The main role of La/sub 2/O/sub 3/ appears to be promotion of the formation of the C/sub 2/H/sub 5/OH precursor, while Pt increased the rate of hydrogenation. 26 refs., 8 figs., 3 tabs.

  4. Fluidity and microstructure formation during flow of Al- SiC particle composites

    Science.gov (United States)

    Yarandi, F. M.; Rohatgi, P. K.; Ray, S.

    1993-06-01

    This article presents the results of casting and spiral fluidity in a Al-7 wt% Si alloy reinforced with 10,15, and 20 vol% SiC particles in permanent molds. The fluidity of the Al-SiC slurry increases linearly with temperature up to about 760 °C. Above this temperature, the casting fluidity of the Al-SiC particle slurry does not change significantly with an increase in temperature. In several cases, the fluidity decreased at temperatures above 760 °C. The fluidity of Al-SiC melts containing 9-μm SiC particles decreased with an increase in volume percentage of SiC up to 15 vol% (the range studied), presumably due to an increase in the viscosity of the melt with increasing volume percentage of dispersoid and changes in thermophysical properties of the composite. However, the fluidity of Al-20 vol% SiC of 14-μm particle size is higher than the fluidity of Al-15 vol% SiC 9-μm particles, indicating the role of particle size and surface area in de-creasing fluidity. Composite slurries travel farther in a channel of larger cross sections compared to channels of smaller cross sections under similar conditions. Casting fluidity increases linearly with an in-crease in cross section of the channel. A model has been proposed to calculate the values of fluidity of the composite as a function of particle volume percent, superheat, flow velocity of the melt, and the cross sec-tion of the flow channel. Experimental observations have been compared with the predictions of the model, and some deviations have been attributed to settling and segregation of SiC particles observed through microstructural examination.

  5. Study of structural transformations and phases formation upon calcination of Zn–Ni–Al hydrotalcite nanosheets

    Indian Academy of Sciences (India)

    Zhanshuang Li; Yanchao Song; Jun Wang; Qi Liu; Piaoping Yang; Milin Zhang

    2011-04-01

    In this paper, we describe a general process for the synthesis of highly crystalline Zn–Ni–Al hydrotalcitelike materials. The structure and thermal decomposition of the prepared samples are studied by XRD, FT–IR, TG–DSC, SEM, TEM and N2 adsorption/desorption. The morphology of large-sized, porous and hexagonal platelike Zn–Ni–Al hydrotalcite is affected by calcination temperature. BET specific surface area and pore volume are observed to increase with increase of the calcination temperature up to 700°C followed by a further decrease with increasing temperature.

  6. Formative versus Reflective Measurement in Executive Functions: A Critique of Willoughby et al.

    Science.gov (United States)

    Peterson, Eric; Welsh, Marilyn C.

    2014-01-01

    Research into executive functioning (EF) has indeed grown exponentially across the past few decades, but as the Willoughby et al. critique makes clear, there remain fundamental questions to be resolved. The crux of their argument is built upon an examination of the confirmatory factor analysis (CFA) approach to understanding executive processes.…

  7. Formation of a random recrystallization texture in heavily cold rolled and annealed Al-1%Si alloy

    DEFF Research Database (Denmark)

    Chen, Y.L.; Huang, T.L.; Gong, X.;

    2013-01-01

    An Al-1%Si alloy cold rolled to a von Mises stain of 4.5 was isothermally annealed at 210°C. A random recrystallization texture was obtained, which was attributed to the effects of particles of different sizes on the nucleation and growth of grains during recrystallization. © (2013) Trans Tech Pu...

  8. Formation, stability and crystal structure of mullite-type Al6-xBxO9

    Science.gov (United States)

    Hoffmann, K.; Hooper, T. J. N.; Murshed, M. M.; Dolotko, O.; Révay, Z.; Senyshyn, A.; Schneider, H.; Hanna, J. V.; Gesing, Th. M.; Fischer, R. X.

    2016-11-01

    Mullite-type Al6-xBxO9 compounds were studied by means of powder diffraction and spectroscopic methods. The backbones of this structure are chains of edge-connected AlO6 octahedra crosslinked by AlO- and BO-polyhedra. Rietveld refinements show that the a and b lattice parameters can be well resolved, thus representing an orthorhombic metric. A continuous decrease of the lattice parameters most pronounced in c-direction indicates a solid solution for Al6-xBxO9 with 1.09≤x≤2. A preference of boron in 3-fold coordination is confirmed by 11B MAS NMR spectroscopy and Fourier calculations based on neutron diffraction data collected at 4 K. Distance Least Squares modeling was performed to simulate a local geometry avoiding long B-O distances linking two octahedral chains by planar BO3 groups yielding split positions for the oxygen atoms and a strong distortion in the octahedral chains. The lattice thermal expansion was calculated using the Grüneisen first-order equation of state Debye-Einstein-Anharmonicity model.

  9. Establishment of an Early Vascular Network Promotes the Formation of Ectopic Bone

    NARCIS (Netherlands)

    Eman, Rhandy M.; Meijer, Henriette A W; Öner, F. Cumhur; Dhert, Wouter J A; Alblas, Jacqueline

    2016-01-01

    Vascularization is crucial for the induction of bone formation. In this study, we investigated the application of two subtypes of peripheral blood-derived endothelial progenitor cells (EPCs) to stimulate vessel formation in ectopic bone constructs. Early and late outgrowth EPCs (E-EPC and L-EPC, res

  10. Dislocation formation and twinning from the crack tip in Ni3Al: molecular dynamics simulations

    Institute of Scientific and Technical Information of China (English)

    Xie Hong-Xian; Wang Chong-Yu; Yu Tao; Du Jun-Ping

    2009-01-01

    The mechanism of low-temperature deformation in a fracture process of L12Ni3Al is studied by molecular dynamic simulations. Owing to the unstable stacking energy, the [011] superdislocation is dissociated into partial dislocations separated by a stacking fault. The simulation results show that when the crack speed is larger than a critical speed, the Shockley partial dislocations will break forth from both the crack tip and the vicinity of the crack tip; subsequently the super intrinsic stacking faults are formed in adjacent {111} planes, meanwhile the super extrinsic stacking faults and twinning also occur. Our simulation results suggcst that at low temperatures the ductile fracture in L12Ni3Al is accompanied by twinning, which is produced by super-intrinsic stacking faults formed in adjacent {111} planes.

  11. FORMATION MECHANISM FOR THE NANOSCALE AMORPHOUS INTERFACE IN PULSE-WELDED AL/FE BIMETALLIC SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jingjing; Yu, Qian; Zhang, Zijiao; Xu, Wei; Sun, Xin

    2016-05-20

    Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the resulted recrystallization occurred on the aluminum side of the interface.

  12. In vitro oxidation of fibrinogen promotes functional alterations and formation of advanced oxidation protein products, an inflammation mediator.

    Science.gov (United States)

    Torbitz, Vanessa Dorneles; Bochi, Guilherme Vargas; de Carvalho, José Antônio Mainardi; de Almeida Vaucher, Rodrigo; da Silva, José Edson Paz; Moresco, Rafael Noal

    2015-01-01

    Fibrinogen (FB) is a soluble blood plasma protein and is a key molecule involved in coagulation. Oxidative modification of proteins, such as the formation of advanced oxidation protein products (AOPP), a heterogeneous family of protein compounds structurally modified and derived from oxidative stress, may be associated with the pathophysiology of a number of chronic inflammatory diseases. Therefore, the aim of this study was to determine whether the formation of this mediator of inflammation occurs from FB and whether its generation is associated with structural changes. Results of the present study suggest that the oxidation of FB may provoke the formation of AOPP, which in turn, may promote functional alterations in FB, thus causing changes in its structural domains and increasing its procoagulant activity.

  13. Formation and dielectric properties of anodic oxide films on Zr–Al alloys

    OpenAIRE

    Koyama, Shun; Aoki, Yoshitaka; Nagata, Shinji; Habazaki, Hiroki

    2011-01-01

    Zr–Al alloys containing up to 26 at.% aluminum, prepared by magnetron sputtering, have been anodized in 0.1 mol dm−3 ammonium pentaborate electrolyte, and the structure and dielectric properties of the resultant anodic oxide films have been examined by grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford backscattering spectroscopy, and AC impedance spectroscopy. The anodic oxide film formed on zirconium consists of monoclinic and tetragonal ZrO2 with the fo...

  14. Heterogeneous dislocation loop formation near grain boundaries in a neutron-irradiated commercial FeCrAl alloy

    Science.gov (United States)

    Field, Kevin G.; Briggs, Samuel A.; Hu, Xunxiang; Yamamoto, Yukinori; Howard, Richard H.; Sridharan, Kumar

    2017-01-01

    FeCrAl alloys are an attractive class of materials for nuclear power applications because of their increased environmental compatibility compared with more traditional nuclear materials. Preliminary studies into the radiation tolerance of FeCrAl alloys under accelerated neutron testing between 300 and 400 °C have shown post-irradiation microstructures containing dislocation loops and a Cr-rich α‧ phase. Although these initial studies established the post-irradiation microstructures, there was little to no focus on understanding the influence of pre-irradiation microstructures on this response. In this study, a well-annealed commercial FeCrAl alloy, Alkrothal 720, was neutron irradiated to 1.8 displacements per atom (dpa) at 382 °C and then the effect of random high-angle grain boundaries on the spatial distribution and size of a dislocation loops, a/2 dislocation loops, and black dot damage was analyzed using on-zone scanning transmission electron microscopy. Results showed a clear heterogeneous dislocation loop formation with a/2 dislocation loops showing an increased number density and size, black dot damage showing a significant number density decrease, and a dislocation loops exhibiting an increased size in the vicinity of the grain boundary. These results suggest the importance of the pre-irradiation microstructure and, specifically, defect sink density spacing to the radiation tolerance of FeCrAl alloys.

  15. Effects of Hybrid Voltages on Oxide Formation on 6061 Al-alloys During Plasma Electrolytic Oxidation

    Institute of Scientific and Technical Information of China (English)

    Kai Wang; Bon Heun Koo; Chan Gyu Lee; Young Joo Kim; Sunghun Lee; Eungsun Byon

    2009-01-01

    Plasma electrolytic oxidation (PEO) is carried out on 6061 Al-alloys in a weak alkaline electrolyte containing NaOH, Na_2SiO_3 and NaCl. Centered on the correlation of composition and structure, analyses by means of X-ray diffration (XRD), scanning electron microscope (SEM) and energy dispersive spectrometry (EDS) are conducted on the specimens, which have been PEO-treated under hybrid voltages of different direct current (DC) values (140-280 V) with constant alternate current (AC) amplitude (200 V). Attention is paid to the composition, properties and growth mechanism of oxide layers formed with hybrid voltages. Moreover, the main effects of DC value are discussed. Ceramic layers with a double-layer structure which combines hard outer and soft inner layers are found to be consist of α-Al_2O_3, γ-Al_2O_3 and mullite. With the DC values increasing, the growth of the ceramic layers tends to have increasingly obvious three-stage feature.

  16. Effect of Sr content on porosity formation in directionally solidified Al-12.3wt.%Si alloy

    Directory of Open Access Journals (Sweden)

    Liao Hengcheng

    2014-09-01

    Full Text Available The influence of Sr addition on pore formation in directionally solidified Al-12.3wt.% alloy was investigated using X-ray detection, optical microscope, and SEM-EDX. Results indicate that addition of Sr significantly increases the number density and volume fraction of porosity. The considerable rise in volume fraction of porosity is attributed to the remarkable increase in the numbers of pores formed. It is found that Sr solute in liquid Al-Si alloy can diffuse into the oxide inclusions to form loose oxide aggregations which have more activity as the nucleation sites for porosity. Adding more Sr considerably increases the numbers of active nucleation sites. There is an obvious fluctuation of pore number density during steady state solidification, which is believed to be related to a fluctuation of local hydrogen supersaturation induced by the competition of pore nucleation and growth for hydrogen solute supplement.

  17. Effect of the formation process of transient liquid phase (TLP) on the interface structure of TiAl joints

    Institute of Scientific and Technical Information of China (English)

    Huiping Duan; Jun Luo; Karl-Heinz Bohm; Mustafa Ko(c)ak

    2005-01-01

    TiAl has been joined employing the transient liquid phase (TLP) bonding with Ti combined with Cu, Ni or Fe foils. Experimental results showed that though the interface structures of the joints are quite different, all the joined zones are composed of five sublayers, i.e. two diffusion zones, two interfacial zones and an interlayer. It has been convinced that the formation process of the transient liquid phase controls the diffusion behavior of melting point depressant (MPD) Cu, Ni, and Fe atoms, which leads to form different interface structures of the joints.

  18. Ultrasound-promoted regio and chemoselective synthesis of pyridazinones and phthalazinones catalyzed by ionic liquid [bmim]Br/AlCl3.

    Science.gov (United States)

    Zare, Leila; Mahmoodi, Nosrat Ollah; Yahyazadeh, Asieh; Nikpassand, Mohammad

    2012-07-01

    The first ultrasound-promoted multicomponent synthesis of pyridazinones and phthalazinones from arenes, cyclic anhydrides and ArNHNH(2) in the presence of an efficient recyclable catalyst, [bmim]Br/AlCl(3), in high yield and short reaction time is reported.

  19. Determination of components in traditional Chinese medicines associated with promoting or inhibiting urinary stone formation

    Directory of Open Access Journals (Sweden)

    Leqing Zhou

    2015-04-01

    Conclusions: Long-term use of TCMs would not increase the risk of urinary stone formation. The potassium content in TCMs is high, which is one possible reason for the prevention of urinary stones by TCMs.

  20. Surfactant process for promoting gas hydrate formation and application of the same

    Science.gov (United States)

    Rogers, Rudy E.; Zhong, Yu

    2002-01-01

    This invention relates to a method of storing gas using gas hydrates comprising forming gas hydrates in the presence of a water-surfactant solution that comprises water and surfactant. The addition of minor amounts of surfactant increases the gas hydrate formation rate, increases packing density of the solid hydrate mass and simplifies the formation-storage-decomposition process of gas hydrates. The minor amounts of surfactant also enhance the potential of gas hydrates for industrial storage applications.

  1. Ubiquilin/Dsk2 promotes inclusion body formation and vacuole (lysosome)-mediated disposal of mutated huntingtin.

    Science.gov (United States)

    Chuang, Kun-Han; Liang, Fengshan; Higgins, Ryan; Wang, Yanchang

    2016-07-01

    Ubiquilin proteins contain a ubiquitin-like domain (UBL) and ubiquitin-associated domain(s) that interact with the proteasome and ubiquitinated substrates, respectively. Previous work established the link between ubiquilin mutations and neurodegenerative diseases, but the function of ubiquilin proteins remains elusive. Here we used a misfolded huntingtin exon I containing a 103-polyglutamine expansion (Htt103QP) as a model substrate for the functional study of ubiquilin proteins. We found that yeast ubiquilin mutant (dsk2Δ) is sensitive to Htt103QP overexpression and has a defect in the formation of Htt103QP inclusion bodies. Our evidence further suggests that the UBL domain of Dsk2 is critical for inclusion body formation. Of interest, Dsk2 is dispensable for Htt103QP degradation when Htt103QP is induced for a short time before noticeable inclusion body formation. However, when the inclusion body forms after a long Htt103QP induction, Dsk2 is required for efficient Htt103QP clearance, as well as for autophagy-dependent delivery of Htt103QP into vacuoles (lysosomes). Therefore our data indicate that Dsk2 facilitates vacuole-mediated clearance of misfolded proteins by promoting inclusion body formation. Of importance, the defect of inclusion body formation in dsk2 mutants can be rescued by human ubiquilin 1 or 2, suggesting functional conservation of ubiquilin proteins.

  2. Berberine promotes the development of atherosclerosis and foam cell formation by inducing scavenger receptor A expression in macrophage

    Institute of Scientific and Technical Information of China (English)

    Ke Li; Wenqi Yao; Xiudan Zheng; Kan Liao

    2009-01-01

    Berberine is identified to lower the serum cholesterol level in human and hamster through the induction of low density lipoproteins (LDL) receptor in hepatic cells. To evaluate its potential in preventing atherosclerosis, the effect of berberine on atherosclerosis development in apolipoprotein E-deficient (apoE-/-) mice was investigated, in apoE-/-mice, berberine induced in vivo foam cell formation and promoted atherosclerosis development. The foam cell for-mation induced by berberine was also observed in mouse RAW264.7 cells, as well as in mouse and human primary macrophages. By inducing scavenger receptor A (SR-A) expression in macrophages, berberine increased the uptake of modified LDL (DiO-Ac-LDL). Berberine-induced SR-A expression was also observed in macrophage foam cells in vivo and in the cells at atherosclerotic lesion. Analysis in RAW264.7 cells indicated that berberine induced SR-A ex-pression by suppressing PTEN expression, which led to sustained Akt activation. Our results suggest that to evaluate the potential of a cholesterol-reducing compound in alleviating atherosclerosis, its effect on the cells involved in ath-erosclerosis development, such as macrophages, should also be considered. Promotion of foam cell formation could counter-balance the beneficial effect of lowering serum cholesterol.

  3. Chinese red yeast rice (Monascus purpureus-fermented rice promotes bone formation

    Directory of Open Access Journals (Sweden)

    Rabie Bakr

    2008-03-01

    Full Text Available Abstract Background Statin can induce the gene expression of bone morphogenetic protein-2. Red yeast rice (RYR, Hongqu, i.e. rice fermented with Monascus purpureus, contains a natural form of statin. This study demonstrates the effects of RYR extract on bone formation. Methods Bone defects were created in the parietal bones of two New Zealand white rabbits. In the test animal, two defects were grafted with collagen matrix mixed with RYR extract. In the control animal, two defects were grafted with collagen matrix alone. UMR 106 cell line was used to test RYR extract in vitro. In the control group, cells were cultured for three durations (24 hours, 48 hours and 72 hours without any intervention. In the RYR group, cells were cultured for the same durations with various concentrations of RYR extract (0.001 g/ml, 0.005 g/ml and 0.01 g/ml. Bicinchoninic acid (BCA assay, 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay and alkaline phosphatase (ALP assay were performed to measure total protein, mitochondrial activity and bone cell formation respectively. Results The test animal showed more formation of new bone in the defects than the control animal. RYR significantly increased the optical density in the MTT assay and ALP activity in vitro. Conclusion RYR extract stimulated new bone formation in bone defects in vivo and increased bone cell formation in vitro.

  4. Formation and characterization of Ni/Al Ohmic contact on n+-type GeSn

    Science.gov (United States)

    Zhang, Xu; Zhang, Dongliang; Zheng, Jun; Liu, Zhi; He, Chao; Xue, Chunlai; Zhang, Guangze; Li, Chuanbo; Cheng, Buwen; Wang, Qiming

    2015-12-01

    In this study, a Ni/Al Ohmic contact on a highly doped n-type GeSn has been investigated. A specific contact resistivity as low as (2.26 ± 0.11) × 10-4 Ω cm2 was obtained with the GeSn sample annealed at a temperature of 450 °C for 30 s. The linear Ohmic behavior was attributed to the low resistance of the Ni(GeSn) phase; this behavior was determined using glancing-angle X-ray diffraction, and the quantum tunneling current through the Schottky barrier narrowed because of high doping; this phenomenon was confirmed from the contact resistance characteristics at different temperatures from 45 to 205 K.

  5. Reducing the formation of FIB-induced FCC layers on Cu-Zn-Al austenite.

    Science.gov (United States)

    Zelaya, Eugenia; Schryvers, Dominique

    2011-01-01

    The irradiation effects of thinning a sample of a Cu-Zn-Al shape memory alloy to electron transparency by a Ga(+) focused ion beam were investigated. This thinning method was compared with conventional electropolishing and Ar(+) ion milling. No implanted Ga was detected but surface FCC precipitation was found as a result of the focused ion beam sample preparation. Decreasing the irradiation dose by lowering the energy and current of the Ga(+) ions did not lead to a complete disappearance of the FCC structure. The latter could only be removed after gentle Ar(+) ion milling of the sample. It was further concluded that the precipitation of the FCC is independent of the crystallographic orientation of the surface.

  6. Effect of the Heusler phase formation on the magnetic behavior of the Cu–10 wt.%Mn alloy with Al and Ag additions

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, T.M., E-mail: thaisa.mary@gmail.com [Instituto de Química – UNESP, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil); Adorno, A.T.; Santos, C.M.A. [Instituto de Química – UNESP, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil); Silva, R.A.G. [Departamento de Ciências Exatas e da Terra – UNIFESP, 09972-270 Diadema, SP (Brazil); Magnani, M. [Instituto de Química – UNESP, Caixa Postal 355, 14801-970 Araraquara, SP (Brazil)

    2015-09-15

    Highlights: • The presence of the Cu{sub 2}MnAl phase was observed in annealed alloys. • Al and Ag additions shift the equilibrium concentration to higher Al values. • There is a correlation between the Ag-rich phase and the Cu{sub 2}MnAl phase. - Abstract: In this work, the formation of the Cu{sub 2}AlMn Heusler phase and its influence on the magnetic behavior of the Cu–Mn–Al–Ag alloys in the range of 8–10 wt.% of aluminum and 2–4 wt.% of silver were studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and saturation magnetization measurements at 4 K. The results showed that there is a correlation between the presence of the Ag-rich phase and the formation of the Cu{sub 2}MnAl phase.

  7. EVIDENCE OF THE SEMI-SOLID FORMATION IN THE MEDICAL GRADE TI6AL4V ALLOY USING INDUCTION HEATING

    Directory of Open Access Journals (Sweden)

    Carlos Roberto Fernandes

    2015-12-01

    Full Text Available One alternative for processing cost reduction with simultaneous improvement of the mechanical properties of the Medical Ti6Al4V alloy is to get its semi-solid feedstock with a non-dendritic microstructure for further processing. The purpose of the present work is to evaluate the possibility of obtaining a semi-solid Ti6Al4V alloy by heating it up from the room temperature to the range temperature between the lines solidus and liquidus, using induction heating. The Ti6Al4V billets underwent heat treatment and quenching for semi-solid formation using a designed device and specific time pulsed profile. The billet temperature reached 1630 oC, and after the cooling rate of 54 oC/s, some samples formed a globular phase characteristic of the semi-solid alloy. This study shows that it is possible to get a semi-solid microstructure of this alloy starting from its solid state.

  8. Human geminin promotes pre-RC formation and DNA replication by stabilizing CDT1 in mitosis

    DEFF Research Database (Denmark)

    Ballabeni, Andrea; Melixetian, Marina; Zamponi, Raffaella

    2004-01-01

    -mediated degradation by inhibiting its ubiquitination. In particular, Geminin ensures basal levels of CDT1 during S phase and its accumulation during mitosis. Consistently, inhibition of Geminin synthesis during M phase leads to impairment of pre-RC formation and DNA replication during the following cell cycle....... Moreover, we show that inhibition of CDK1 during mitosis, and not Geminin depletion, is sufficient for premature formation of pre-RCs, indicating that CDK activity is the major mitotic inhibitor of licensing in human cells. Taken together with recent data from our laboratory, our results demonstrate...

  9. Comparison of hyaluronidase expression, invasiveness and tubule formation promotion in ER (-) and ER (+) breast cancer cell lines in vitro

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-yi; TAN Jin-xiang; Marc Vasse; Bertrand Delpech; REN Guo-sheng

    2009-01-01

    Background Hyaluronidase (Hyase) is an enzyme which hydrolyses hyaluronan (HA), a large nonsulfated glycosaminoglycan. Several genes have been identified to code for hyaluronidases in humans. Its role has only recently been underlined in the invasion of prostate cancer, colonic cancer, and breast cancer. Moreover, the findings were in agreement with some experimental results which showed that HA-derived oligosaccharides had angiogenesis-promoting activity. All these findings prompted us to investigate factors that had been characterized as putative invasive factors in different human breast cancer-derived cell lines.Methods We selected two series of human breast cancer-derived cell lines whose expression of estrogen receptors (ER) was previously published. Hyaluronidase secretion in culture medium and expression of matrix metallo-proteinase (MMP)-9, cathepsin-D (cath-D) and vascular endothelial growth factor (VEGF) by cells were determined. We also investigated cell invasiveness in the Matrigel invasion assay, and studied the capability of cancer cells to promote in vitro formation of tubules by endothelial cells.Results ER(-) cells secreted significantly more hyaluronidase (P <0.001) and expressed significantly more VEGF (P <0.01), MMP-9 (P <0.05) and cath-D (P <0.0001) than ER(+) cells. Invasion through Matdgel by ER(-) Hyase(+) cells was significantly higher than that by ER(+) Hyase(-) cells (P<0.05). In both cases, invasion was decreased by heparin (P <0.05). When ECV-304 endothelial cells were co-cultivated in millicell chambers with cancer cells, ECV-304 cells were induced to form tubules. Tubule formation was demonstrated to be more prominent with ER(-) Hyase(+) cells than with ER(+) Hyase(-) cells (P <0.05).Conclusion Invasive features of ER(-) breast cancer cells can be characterized in vitro by an invasive Matrigel assay,as the induction of tubule formation by ECV-304 endothelial cells, higher secretion of hyaluronidase, and higher expression of

  10. Loss of expression and promoter methylation of SLIT2 are associated with sessile serrated adenoma formation.

    Science.gov (United States)

    Beggs, Andrew D; Jones, Angela; Shepherd, Neil; Arnaout, Abed; Finlayson, Caroline; Abulafi, A Muti; Morton, Dion G; Matthews, Glenn M; Hodgson, Shirley V; Tomlinson, Ian P M

    2013-05-01

    Serrated adenomas form a distinct subtype of colorectal pre-malignant lesions that may progress to malignancy along a different molecular pathway than the conventional adenoma-carcinoma pathway. Previous studies have hypothesised that BRAF mutation and promoter hypermethylation plays a role, but the evidence for this is not robust. We aimed to carry out a whole-genome loss of heterozygosity analysis, followed by targeted promoter methylation and expression analysis to identify potential pathways in serrated adenomas. An initial panel of 9 sessile serrated adenomas (SSA) and one TSA were analysed using Illumina Goldengate HumanLinkage panel arrays to ascertain regions of loss of heterozygosity. This was verified via molecular inversion probe analysis and microsatellite analysis of a further 32 samples. Methylation analysis of genes of interest was carried out using methylation specific PCR (verified by pyrosequencing) and immunohistochemistry used to correlate loss of expression of genes of interest. All experiments used adenoma samples and normal tissue samples as control. SSA samples were found on whole-genome analysis to have consistent loss of heterozygosity at 4p15.1-4p15.31, which was not found in the sole TSA, adenomas, or normal tissues. Genes of interest in this region were PDCH7 and SLIT2, and combined MSP/IHC analysis of these genes revealed significant loss of SLIT2 expression associated with promoter methylation of SLIT2. Loss of expression of SLIT2 by promoter hypermethylation and loss of heterozygosity events is significantly associated with serrated adenoma development, and SLIT2 may represent a epimutated tumour suppressor gene according to the Knudson "two hit" hypothesis.

  11. Loss of expression and promoter methylation of SLIT2 are associated with sessile serrated adenoma formation.

    Directory of Open Access Journals (Sweden)

    Andrew D Beggs

    2013-05-01

    Full Text Available Serrated adenomas form a distinct subtype of colorectal pre-malignant lesions that may progress to malignancy along a different molecular pathway than the conventional adenoma-carcinoma pathway. Previous studies have hypothesised that BRAF mutation and promoter hypermethylation plays a role, but the evidence for this is not robust. We aimed to carry out a whole-genome loss of heterozygosity analysis, followed by targeted promoter methylation and expression analysis to identify potential pathways in serrated adenomas. An initial panel of 9 sessile serrated adenomas (SSA and one TSA were analysed using Illumina Goldengate HumanLinkage panel arrays to ascertain regions of loss of heterozygosity. This was verified via molecular inversion probe analysis and microsatellite analysis of a further 32 samples. Methylation analysis of genes of interest was carried out using methylation specific PCR (verified by pyrosequencing and immunohistochemistry used to correlate loss of expression of genes of interest. All experiments used adenoma samples and normal tissue samples as control. SSA samples were found on whole-genome analysis to have consistent loss of heterozygosity at 4p15.1-4p15.31, which was not found in the sole TSA, adenomas, or normal tissues. Genes of interest in this region were PDCH7 and SLIT2, and combined MSP/IHC analysis of these genes revealed significant loss of SLIT2 expression associated with promoter methylation of SLIT2. Loss of expression of SLIT2 by promoter hypermethylation and loss of heterozygosity events is significantly associated with serrated adenoma development, and SLIT2 may represent a epimutated tumour suppressor gene according to the Knudson "two hit" hypothesis.

  12. Friction Stir Welding of Al Alloy 2219-T8: Part I-Evolution of Precipitates and Formation of Abnormal Al2Cu Agglomerates

    Science.gov (United States)

    Kang, Ju; Feng, Zhi-Cao; Frankel, G. S.; Huang, I. Wen; Wang, Guo-Qing; Wu, Ai-Ping

    2016-09-01

    Friction stir welding was performed on AA2219-T8 plates with 6.31 wt pct Cu. The thermal cycles were measured in different regions of the joint during welding. Differential scanning calorimetry and transmission electron microscopy were utilized to analyze the evolution of precipitates in the joint. The relationships between welding peak temperature, precipitate evolution, and microhardness distribution are discussed. The temperature in the heat-affected zone (HAZ) ranged from 453 K to 653 K (180 °C to 380 °C). The θ″ and some θ' phases redissolved into the HAZ matrix, while the rest of the θ' phases coarsened. In the thermomechanically affected zone (TMAZ), the temperature range was from 653 K to 673 K (380 °C to 400 °C), causing both θ″ phase and θ' phase to redissolve. In the weld nugget zone (WNZ), all the θ″, θ', and some of the θ phase (Al2Cu) redissolved. Abnormal θ particles were observed in the WNZ, including agglomerated θ with sizes around 100 to 1000 µm and a ring-shaped distribution of normal size θ particles. The formation of abnormal θ particles resulted from metal plastic flow during welding and the high content of Cu in AA2219. No abnormal θ particles were observed in joints of another AA2219 plate, which had a lower Cu content of 5.83 wt pct.

  13. Using Common Formative Assessments to Promote Student Achievement: A Case Study of Practice, Leadership, and Culture

    Science.gov (United States)

    Wall, Patricia T. C.

    2012-01-01

    It is the moral responsibility of educators to work diligently to provide every student with rich, challenging coursework in efforts to prepare them for post high school careers and education. The use of common formative assessments provides teachers with the valuable, timely information they need to make instructional decisions that will better…

  14. Embedded Formative Assessment and Classroom Process Quality: How Do They Interact in Promoting Science Understanding?

    Science.gov (United States)

    Decristan, Jasmin; Klieme, Eckhard; Kunter, Mareike; Hochweber, Jan; Büttner, Gerhard; Fauth, Benjamin; Hondrich, A. Lena; Rieser, Svenja; Hertel, Silke; Hardy, Ilonca

    2015-01-01

    In this study we examine the interplay between curriculum-embedded formative assessment--a well-known teaching practice--and general features of classroom process quality (i.e., cognitive activation, supportive climate, classroom management) and their combined effect on elementary school students' understanding of the scientific concepts of…

  15. Acetoacetate promotes the formation of fluorescent advanced glycation end products (AGEs).

    Science.gov (United States)

    Bohlooli, Mousa; Ghaffari-Moghaddam, Mansour; Khajeh, Mostafa; Aghashiri, Zohre; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

    2016-12-01

    Acetoacetate (AA) is an important ketone body, which produces reactive oxygen species (ROS). Advanced glycation end products (AGEs) are defined as final products of glycation process whose production is influenced by the levels of ROS. The accumulation of AGEs in the body contributes to pathogenesis of many diseases including complications of diabetes, and Alzheimer's and Parkinson's disease. Here, we evaluated the impact of AA on production of AGEs upon incubation of human serum albumin (HSA) with glucose. The effect of AA on the AGEs formation of HSA was studied under physiological conditions after incubation with glucose for 35 days. The physical techniques including circular dichroism (CD) and fluorescence spectroscopy were used to assess the impact of AA on formation and structural changes of glycated HSA (GHSA). Our results indicated that the secondary and tertiary structural changes of GHSA were increased in the presence of AA. The fluorescence intensity measurements of AGEs also showed an increase in AGEs formation. Acetoacetate has an activator effect in formation of AGEs through ROS production. The presence of AA may result in enhanced glycation in the presence of glucose and severity of complications associated with accumulation of AGEs.

  16. Thermodynamics of Complex Sulfide Inclusion Formation in Ca-Treated Al-Killed Structural Steel

    Science.gov (United States)

    Guo, Yin-tao; He, Sheng-ping; Chen, Gu-jun; Wang, Qian

    2016-08-01

    Controlling the morphology of the sulfide inclusion is of vital importance in enhancing the properties of structural steel. Long strip-shaped sulfides in hot-rolled steel can spherize when, instead of the inclusion of pure single-phase MnS, the guest is a complex sulfide, such as an oxide-sulfide duplex and a solid-solution sulfide particle. In this study, the inclusions in a commercial rolled structural steel were investigated. Spherical and elongated oxide-sulfide duplex as well as single-phase (Mn,Ca)S solid solution inclusions were observed in the steel. A thermodynamic equilibrium between the oxide and sulfide inclusions was proposed to understand the oxide-sulfide duplex inclusion formation. Based on the equilibrium solidification principle, thermodynamic discussions on inclusion precipitation during the solidification process were performed for both general and resulfurized structural steel. The predicted results of the present study agreed well with the experimental ones.

  17. Preformed template fluctuations promote fibril formation: Insights from lattice and all-atom models

    Energy Technology Data Exchange (ETDEWEB)

    Kouza, Maksim, E-mail: mkouza@chem.uw.edu.pl; Kolinski, Andrzej [Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warszaw (Poland); Co, Nguyen Truong [Department of Physics, Institute of Technology, National University of HCM City, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City (Viet Nam); Institute for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City (Viet Nam); Nguyen, Phuong H. [Laboratoire de Biochimie Theorique, UPR 9080 CNRS, IBPC, Universite Paris 7, 13 rue Pierre et Marie Curie, 75005 Paris (France); Li, Mai Suan, E-mail: masli@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

    2015-04-14

    Fibril formation resulting from protein misfolding and aggregation is a hallmark of several neurodegenerative diseases such as Alzheimer’s and Parkinson’s diseases. Despite the fact that the fibril formation process is very slow and thus poses a significant challenge for theoretical and experimental studies, a number of alternative pictures of molecular mechanisms of amyloid fibril formation have been recently proposed. What seems to be common for the majority of the proposed models is that fibril elongation involves the formation of pre-nucleus seeds prior to the creation of a critical nucleus. Once the size of the pre-nucleus seed reaches the critical nucleus size, its thermal fluctuations are expected to be small and the resulting nucleus provides a template for sequential (one-by-one) accommodation of added monomers. The effect of template fluctuations on fibril formation rates has not been explored either experimentally or theoretically so far. In this paper, we make the first attempt at solving this problem by two sets of simulations. To mimic small template fluctuations, in one set, monomers of the preformed template are kept fixed, while in the other set they are allowed to fluctuate. The kinetics of addition of a new peptide onto the template is explored using all-atom simulations with explicit water and the GROMOS96 43a1 force field and simple lattice models. Our result demonstrates that preformed template fluctuations can modulate protein aggregation rates and pathways. The association of a nascent monomer with the template obeys the kinetics partitioning mechanism where the intermediate state occurs in a fraction of routes to the protofibril. It was shown that template immobility greatly increases the time of incorporating a new peptide into the preformed template compared to the fluctuating template case. This observation has also been confirmed by simulation using lattice models and may be invoked to understand the role of template fluctuations in

  18. Preformed template fluctuations promote fibril formation: insights from lattice and all-atom models.

    Science.gov (United States)

    Kouza, Maksim; Co, Nguyen Truong; Nguyen, Phuong H; Kolinski, Andrzej; Li, Mai Suan

    2015-04-14

    Fibril formation resulting from protein misfolding and aggregation is a hallmark of several neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Despite the fact that the fibril formation process is very slow and thus poses a significant challenge for theoretical and experimental studies, a number of alternative pictures of molecular mechanisms of amyloid fibril formation have been recently proposed. What seems to be common for the majority of the proposed models is that fibril elongation involves the formation of pre-nucleus seeds prior to the creation of a critical nucleus. Once the size of the pre-nucleus seed reaches the critical nucleus size, its thermal fluctuations are expected to be small and the resulting nucleus provides a template for sequential (one-by-one) accommodation of added monomers. The effect of template fluctuations on fibril formation rates has not been explored either experimentally or theoretically so far. In this paper, we make the first attempt at solving this problem by two sets of simulations. To mimic small template fluctuations, in one set, monomers of the preformed template are kept fixed, while in the other set they are allowed to fluctuate. The kinetics of addition of a new peptide onto the template is explored using all-atom simulations with explicit water and the GROMOS96 43a1 force field and simple lattice models. Our result demonstrates that preformed template fluctuations can modulate protein aggregation rates and pathways. The association of a nascent monomer with the template obeys the kinetics partitioning mechanism where the intermediate state occurs in a fraction of routes to the protofibril. It was shown that template immobility greatly increases the time of incorporating a new peptide into the preformed template compared to the fluctuating template case. This observation has also been confirmed by simulation using lattice models and may be invoked to understand the role of template fluctuations in

  19. Biofuel-Promoted Polychlorinated Dibenzodioxin/furan Formation in an Iron-Catalyzed Diesel Particle Filter.

    Science.gov (United States)

    Heeb, Norbert V; Rey, Maria Dolores; Zennegg, Markus; Haag, Regula; Wichser, Adrian; Schmid, Peter; Seiler, Cornelia; Honegger, Peter; Zeyer, Kerstin; Mohn, Joachim; Bürki, Samuel; Zimmerli, Yan; Czerwinski, Jan; Mayer, Andreas

    2015-08-04

    Iron-catalyzed diesel particle filters (DPFs) are widely used for particle abatement. Active catalyst particles, so-called fuel-borne catalysts (FBCs), are formed in situ, in the engine, when combusting precursors, which were premixed with the fuel. The obtained iron oxide particles catalyze soot oxidation in filters. Iron-catalyzed DPFs are considered as safe with respect to their potential to form polychlorinated dibenzodioxins/furans (PCDD/Fs). We reported that a bimetallic potassium/iron FBC supported an intense PCDD/F formation in a DPF. Here, we discuss the impact of fatty acid methyl ester (FAME) biofuel on PCDD/F emissions. The iron-catalyzed DPF indeed supported a PCDD/F formation with biofuel but remained inactive with petroleum-derived diesel fuel. PCDD/F emissions (I-TEQ) increased 23-fold when comparing biofuel and diesel data. Emissions of 2,3,7,8-TCDD, the most toxic congener [toxicity equivalence factor (TEF) = 1.0], increased 90-fold, and those of 2,3,7,8-TCDF (TEF = 0.1) increased 170-fold. Congener patterns also changed, indicating a preferential formation of tetra- and penta-chlorodibenzofurans. Thus, an inactive iron-catalyzed DPF becomes active, supporting a PCDD/F formation, when operated with biofuel containing impurities of potassium. Alkali metals are inherent constituents of biofuels. According to the current European Union (EU) legislation, levels of 5 μg/g are accepted. We conclude that risks for a secondary PCDD/F formation in iron-catalyzed DPFs increase when combusting potassium-containing biofuels.

  20. Formation of hypereutectic silicon particles in hypoeutectic Al-Si alloys under the influence of high-intensity ultrasonic vibration

    Directory of Open Access Journals (Sweden)

    Xiaogang Jian

    2013-03-01

    Full Text Available The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were obtained. Polyhedral silicon particles, which should form in a hypereutectic alloy, were obtained in a hypoeutectic Al-Si alloy near the ultrasonic radiator where the silicon concentration was higher than the eutectic composition. The formation of hypereutectic silicon near the radiator surface indicates that high-intensity ultrasonic vibration can be used to influence the phase transformation process of metals and alloys. The size and morphology of both the silicon phase and the aluminum phase varies with increasing distance from the ultrasonic probe/radiator. Silicon morphology develops into three zones. Polyhedral primary silicon particles present in zone I, within 15 mm from the ultrasonic probe/radiator. Transition from hypereutectic silicon to eutectic silicon occurs in zone II about 15 to 20 祄 from the ultrasonic probe/radiator. The bulk of the ingot is in zone III and is hypoeutectic Al-Si alloy containing fine lamellar and fibrous eutectic silicon. The grain size is about 15 to 25 祄 in zone I, 25 to 35 祄 in zone II, and 25 to 55 祄 in zone III. The morphology of the primary ?Al phase is also changed from dendritic (in untreated samples to globular. Phase evolution during the solidification process of the alloy subjected to ultrasonic vibration is described.

  1. Development of a reduced model of formation reactions in Zr-Al nanolaminates

    KAUST Repository

    Vohra, Manav

    2014-12-15

    A computational model of anaerobic reactions in metallic multilayered systems with an equimolar composition of zirconium and aluminum is developed. The reduced reaction formalism of M. Salloum and O. M. Knio, Combust. Flame 157(2): 288–295 (2010) is adopted. Attention is focused on quantifying intermixing rates based on experimental measurements of uniform ignition as well as measurements of self-propagating front velocities. Estimates of atomic diffusivity are first obtained based on a regression analysis. A more elaborate Bayesian inference formalism is then applied in order to assess the impact of uncertainties in the measurements, potential discrepancies between predictions and observations, as well as the sensitivity of predictions to inferred parameters. Intermixing rates are correlated in terms of a composite Arrhenius law, which exhibits a discontinuity around the Al melting temperature. Analysis of the predictions indicates that Arrhenius parameters inferred for the low-temperature branch lie within a tight range, whereas the parameters of the high-temperature branch are characterized by higher uncertainty. The latter is affected by scatter in the experimental measurements, and the limited range of bilayers where observations are available. For both branches, the predictions exhibit higher sensitivity to the activation energy than the pre-exponent, whose posteriors are highly correlated.

  2. Catalytic dehydration of carbohydrates suspended in organic solvents promoted by AlCl3 /SiO2 coated with choline chloride.

    Science.gov (United States)

    Yang, Jie; De Oliveira Vigier, Karine; Gu, Yanlong; Jérôme, François

    2015-01-01

    We show that the coating of choline chloride on silica-supported AlCl3 allows the dehydration of carbohydrates to successfully proceed in low boiling point organic solvents. The concept is based on the in situ formation of a deep eutectic liquid phase on the catalyst surface, thus facilitating the interaction between the solid catalyst and insoluble carbohydrate.

  3. Thermodynamic promotion of carbon dioxide-clathrate hydrate formation by tetrahydrofuran, cyclopentane and their mixtures

    DEFF Research Database (Denmark)

    Herslund, Peter Jørgensen; Thomsen, Kaj; Abildskov, Jens

    2013-01-01

    Gas clathrate hydrate dissociation pressures are reported for mixtures of carbon dioxide, water and thermodynamic promoters forming structure II hydrates.Hydrate (H)-aqueous liquid (Lw)-vapour (V) equilibrium pressures for the ternary system composed of water, tetrahydrofuran (THF), and carbon....... It is shown that upon adding THF to the pure aqueous phase to form a 4mass percent solution, the equilibrium pressure of the formed hydrates may be lowered compared to the ternary system of water, cyclopentane and carbon dioxide. © 2013 Elsevier Ltd....

  4. Lewis acid promoted dual bond formation: facile synthesis of dihydrocoumarins and spiro-tetracyclic dihydrocoumarins.

    Science.gov (United States)

    Niharika, Pedireddi; Ramulu, Bokka Venkat; Satyanarayana, Gedu

    2014-07-07

    Lewis acid (FeCl3) mediated dual bond (C-C and C-O) formation for synthesis of 3,4-dihydrocoumarins is presented. This method has successfully delivered a number of dihydrocoumarins containing dense functionalities on the aromatic ring. Significantly, the present method enabled achieving dihydrocoumarins with tertiary as well as quaternary carbon atoms at the benzylic position. Gratifyingly, the novel spiro-tetracyclic lactones have also been dextrously prepared using this process.

  5. Canonical Wnt signaling promotes early hematopoietic progenitor formation and erythroid specification during embryonic stem cell differentiation.

    Directory of Open Access Journals (Sweden)

    Anuradha Tarafdar

    Full Text Available The generation of hematopoietic stem cells (HSCs during development is a complex process linked to morphogenic signals. Understanding this process is important for regenerative medicine applications that require in vitro production of HSC. In this study we investigated the effects of canonical Wnt/β-catenin signaling during early embryonic differentiation and hematopoietic specification using an embryonic stem cell system. Our data clearly demonstrates that following early differentiation induction, canonical Wnt signaling induces a strong mesodermal program whilst maintaining a degree of stemness potential. This involved a complex interplay between β-catenin/TCF/LEF/Brachyury/Nanog. β-catenin mediated up-regulation of TCF/LEF resulted in enhanced brachyury levels, which in-turn lead to Nanog up-regulation. During differentiation, active canonical Wnt signaling also up-regulated key transcription factors and cell specific markers essential for hematopoietic specification, in particular genes involved in establishing primitive erythropoiesis. This led to a significant increase in primitive erythroid colony formation. β-catenin signaling also augmented early hematopoietic and multipotent progenitor (MPP formation. Following culture in a MPP specific cytokine cocktail, activation of β-catenin suppressed differentiation of the early hematopoietic progenitor population, with cells displaying a higher replating capacity and a propensity to form megakaryocytic erythroid progenitors. This bias towards erythroid lineage commitment was also observed when hematopoietic progenitors were directed to undergo myeloid colony formation. Overall this study underscores the importance of canonical Wnt/β-catenin signaling in mesodermal specification, primitive erythropoiesis and early hematopietic progenitor formation during hematopoietic induction.

  6. Canonical Wnt signaling promotes early hematopoietic progenitor formation and erythroid specification during embryonic stem cell differentiation.

    Science.gov (United States)

    Tarafdar, Anuradha; Dobbin, Edwina; Corrigan, Pamela; Freeburn, Robin; Wheadon, Helen

    2013-01-01

    The generation of hematopoietic stem cells (HSCs) during development is a complex process linked to morphogenic signals. Understanding this process is important for regenerative medicine applications that require in vitro production of HSC. In this study we investigated the effects of canonical Wnt/β-catenin signaling during early embryonic differentiation and hematopoietic specification using an embryonic stem cell system. Our data clearly demonstrates that following early differentiation induction, canonical Wnt signaling induces a strong mesodermal program whilst maintaining a degree of stemness potential. This involved a complex interplay between β-catenin/TCF/LEF/Brachyury/Nanog. β-catenin mediated up-regulation of TCF/LEF resulted in enhanced brachyury levels, which in-turn lead to Nanog up-regulation. During differentiation, active canonical Wnt signaling also up-regulated key transcription factors and cell specific markers essential for hematopoietic specification, in particular genes involved in establishing primitive erythropoiesis. This led to a significant increase in primitive erythroid colony formation. β-catenin signaling also augmented early hematopoietic and multipotent progenitor (MPP) formation. Following culture in a MPP specific cytokine cocktail, activation of β-catenin suppressed differentiation of the early hematopoietic progenitor population, with cells displaying a higher replating capacity and a propensity to form megakaryocytic erythroid progenitors. This bias towards erythroid lineage commitment was also observed when hematopoietic progenitors were directed to undergo myeloid colony formation. Overall this study underscores the importance of canonical Wnt/β-catenin signaling in mesodermal specification, primitive erythropoiesis and early hematopietic progenitor formation during hematopoietic induction.

  7. Reactive oxidation products promote secondary organic aerosol formation from green leaf volatiles

    Directory of Open Access Journals (Sweden)

    J. F. Hamilton

    2009-06-01

    Full Text Available Green leaf volatiles (GLVs are an important group of chemicals released by vegetation which have emission fluxes that can be significantly increased when plants are damaged or stressed. A series of simulation chamber experiments has been conducted at the European Photoreactor in Valencia, Spain, to investigate secondary organic aerosol (SOA formation from the atmospheric oxidation of the major GLVs cis-3-hexenylacetate and cis-3-hexen-1-ol. Liquid chromatography-ion trap mass spectrometry was used to identify chemical species present in the SOA. Cis-3-hexen-1-ol proved to be a more efficient SOA precursor due to the high reactivity of its first generation oxidation product, 3-hydroxypropanal, which can hydrate and undergo further reactions with other aldehydes resulting in SOA dominated by higher molecular weight oligomers. The lower SOA yields produced from cis-3-hexenylacetate are attributed to the acetate functionality, which inhibits oligomer formation in the particle phase. Based on observed SOA yields and best estimates of global emissions, these compounds may be calculated to be a substantial unidentified global source of SOA, contributing 1–5 TgC yr−1, equivalent to around a third of that predicted from isoprene. Molecular characterization of the SOA, combined with organic mechanistic information, has provided evidence that the formation of organic aerosols from GLVs is closely related to the reactivity of their first generation atmospheric oxidation products, and indicates that this may be a simple parameter that could be used in assessing the aerosol formation potential for other unstudied organic compounds in the atmosphere.

  8. Wave energy focusing to subsurface poroelastic formations to promote oil mobilization

    KAUST Repository

    Karve, P. M.

    2015-04-22

    We discuss an inverse source formulation aimed at focusing wave energy produced by ground surface sources to target subsurface poroelastic formations. The intent of the focusing is to facilitate or enhance the mobility of oil entrapped within the target formation. The underlying forward wave propagation problem is cast in two spatial dimensions for a heterogeneous poroelastic target embedded within a heterogeneous elastic semi-infinite host. The semi-infiniteness of the elastic host is simulated by augmenting the (finite) computational domain with a buffer of perfectly matched layers. The inverse source algorithm is based on a systematic framework of partial-differential-equation-constrained optimization. It is demonstrated, via numerical experiments, that the algorithm is capable of converging to the spatial and temporal characteristics of surface loads that maximize energy delivery to the target formation. Consequently, the methodology is well-suited for designing field implementations that could meet a desired oil mobility threshold. Even though the methodology, and the results presented herein are in two dimensions, extensions to three dimensions are straightforward.

  9. Augmin promotes meiotic spindle formation and bipolarity in Xenopus egg extracts.

    Science.gov (United States)

    Petry, Sabine; Pugieux, Céline; Nédélec, François J; Vale, Ronald D

    2011-08-30

    Female meiotic spindles in many organisms form in the absence of centrosomes, the organelle typically associated with microtubule (MT) nucleation. Previous studies have proposed that these meiotic spindles arise from RanGTP-mediated MT nucleation in the vicinity of chromatin; however, whether this process is sufficient for spindle formation is unknown. Here, we investigated whether a recently proposed spindle-based MT nucleation pathway that involves augmin, an 8-subunit protein complex, also contributes to spindle morphogenesis. We used an assay system in which hundreds of meiotic spindles can be observed forming around chromatin-coated beads after introduction of Xenopus egg extracts. Spindles forming in augmin-depleted extracts showed reduced rates of MT formation and were predominantly multipolar, revealing a function of augmin in stabilizing the bipolar shape of the acentrosomal meiotic spindle. Our studies also have uncovered an apparent augmin-independent MT nucleation process from acentrosomal poles, which becomes increasingly active over time and appears to partially rescue the spindle defects that arise from augmin depletion. Our studies reveal that spatially and temporally distinct MT generation pathways from chromatin, spindle MTs, and acentrosomal poles all contribute to robust bipolar spindle formation in meiotic extracts.

  10. The use of bovine screws to promote bone formation using a tibia model in dogs

    Science.gov (United States)

    Bianchini, Marco Aurélio; Pontual, Marco Antônio B; Bez, Leonardo; Benfatti, César Augusto M; Boabaid, Fernanda; Somerman, Martha J; Magini, Ricardo S

    2013-01-01

    The objective of this study was to evaluate the use of a unique resorbable bovine bone screw, to stimulate bone formation. Bovine bone screws were inserted in the tibia beagle dogs. Each animal received 8 screws, divided into Groups A (screws + no membranes), B (screws + titanium reinforced membranes) and C (bone defects treated with autogenous bone grafts). Animals were sacrificed at 2, 4 and 6 months. New bone was measured with a periodontal probe and reported an average of 7.4 mm in vertical bone gain for Group B, 3.6 mm for Group A and 1.7 mm for Group C. Submission to Kruskal-Wallis test showed statistical differences between groups (p<0,05). Histological examination revealed an intimate contact between the newly formed bone and the resorbing bone screws. Conclusion: Bovine bone screws provide environment for new bone formation and thus may provide an alternative therapy for enhancing bone formation vertically, including for regenerative procedures as well as prior to implant therapy. PMID:23058228

  11. Promoting a-Al2O3 layer growth upon high temperature oxidation of NiCoCrAlY alloys

    NARCIS (Netherlands)

    Nijdam, T.J.

    2005-01-01

    The turbine blades in gas turbine engines need to be protected against high temperature oxidation and corrosion with a coating system. This coating system comprises of a Ni-based superalloy substrate, a NiCoCrAlY bond coating (BC) and an insulating ceramic thermal barrier coating (TBC). Good protect

  12. A Novel Investigation of the Formation of Titanium Oxide Nanotubes on Thermally Formed Oxide of Ti-6Al-4V.

    Science.gov (United States)

    Butt, Arman; Hamlekhan, Azhang; Patel, Sweetu; Royhman, Dmitry; Sukotjo, Cortino; Mathew, Mathew T; Shokuhfar, Tolou; Takoudis, Christos

    2015-10-01

    Traditionally, titanium oxide (TiO2) nanotubes (TNTs) are anodized on Ti-6Al-4V alloy (Ti-V) surfaces with native TiO2 (amorphous TiO2); subsequent heat treatment of anodized surfaces has been observed to enhance cellular response. As-is bulk Ti-V, however, is often subjected to heat treatment, such as thermal oxidation (TO), to improve its mechanical properties. Thermal oxidation treatment of Ti-V at temperatures greater than 200°C and 400°C initiates the formation of anatase and rutile TiO2, respectively, which can affect TNT formation. This study aims at understanding the TNT formation mechanism on Ti-V surfaces with TO-formed TiO2 compared with that on as-is Ti-V surfaces with native oxide. Thermal oxidation-formed TiO2 can affect TNT formation and surface wettability because TO-formed TiO2 is expected to be part of the TNT structure. Surface characterization was carried out with field emission scanning electron microscopy, energy dispersive x-ray spectroscopy, water contact angle measurements, and white light interferometry. The TNTs were formed on control and 300°C and 600°C TO-treated Ti-V samples, and significant differences in TNT lengths and surface morphology were observed. No difference in elemental composition was found. Thermal oxidation and TO/anodization treatments produced hydrophilic surfaces, while hydrophobic behavior was observed over time (aging) for all samples. Reduced hydrophobic behavior was observed for TO/anodized samples when compared with control, control/anodized, and TO-treated samples. A method for improved surface wettability and TNT morphology is therefore discussed for possible applications in effective osseointegration of dental and orthopedic implants.

  13. FRK inhibits migration and invasion of human glioma cells by promoting N-cadherin/β-catenin complex formation.

    Science.gov (United States)

    Shi, Qiong; Song, Xu; Wang, Jun; Gu, Jia; Zhang, Weijian; Hu, Jinxia; Zhou, Xiuping; Yu, Rutong

    2015-01-01

    Fyn-related kinase (FRK), a member of Src-related tyrosine kinases, is recently reported to function as a potent tumor suppressor in several cancer types. Our previous study has also shown that FRK over-expression inhibited the migration and invasion of glioma cells. However, the mechanism of FRK effect on glioma cell migration and invasion, a feature of human malignant gliomas, is still not clear. In this study, we found that FRK over-expression increased the protein level of N-cadherin, but not E-cadherin. Meanwhile, FRK over-expression promoted β-catenin translocation to the plasma membrane, where it formed complex with N-cadherin, while decreased β-catenin level in the nuclear fraction. In addition, down-regulation of N-cadherin by siRNA promoted the migration and invasion of glioma U251 and U87 cells and abolished the inhibitory effect of FRK on glioma cell migration and invasion. In summary, these results indicate that FRK inhibits migration and invasion of human glioma cells by promoting N-cadherin/β-catenin complex formation.

  14. Promotion Effect of CaO Modification on Mesoporous Al2O3-Supported Ni Catalysts for CO2 Methanation

    Directory of Open Access Journals (Sweden)

    Wen Yang

    2016-01-01

    Full Text Available The catalysts Ni/Al2O3 and CaO modified Ni/Al2O3 were prepared by impregnation method and applied for methanation of CO2. The catalysts were characterized by N2 adsorption/desorption, temperature-programmed reduction of H2 (H2-TPR, X-ray diffraction (XRD, and temperature-programmed desorption of CO2 and H2 (CO2-TPD and H2-TPD techniques, respectively. TPR and XRD results indicated that CaO can effectively restrain the growth of NiO nanoparticles, improve the dispersion of NiO, and weaken the interaction between NiO and Al2O3. CO2-TPD and H2-TPD results suggested that CaO can change the environment surrounding of CO2 and H2 adsorption and thus the reactants on the Ni atoms can be activated more easily. The modified Ni/Al2O3 showed better catalytic activity than pure Ni/Al2O3. Ni/CaO-Al2O3 showed high CO2 conversion especially at low temperatures compared to Ni/Al2O3, and the selectivity to CH4 was very close to 1. The high CO2 conversion over Ni/CaO-Al2O3 was mainly caused by the surface coverage by CO2-derived species on CaO-Al2O3 surface.

  15. Enhancement of human ACAT1 gene expression to promote the macrophage-derived foam cell formation by dexamethasone

    Institute of Scientific and Technical Information of China (English)

    Li YANG; Ta Yuan CHANG; Bo Liang LI; Jin Bo YANG; Jia CHEN; Guang Yao YU; Pei ZHOU; Lei LEI; Zhen Zhen WANG; Catherine CY CHANG; XinYing YANG

    2004-01-01

    In macrophages, the accumulation of cholesteryl esters synthesized by the activated acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) results in the foam cell formation, a hallmark of early atherosclerotic lesions. In this study,with the treatment of a glucocorticoid hormone dexamethasone (Dex), lipid staining results clearly showed the large accumulation of lipid droplets containing cholesteryl esters in THP- 1-derived macrophages exposed to lower concentration of the oxidized low-density lipoprotein (ox-LDL). More notably, when treated together with specific anti-ACAT inhibitors, the abundant cholesteryl ester accumulation was markedly diminished in THP-l-derived macrophages, confirming that ACAT is the key enzyme responsible for intracellular cholesteryl ester synthesis. RT-PCR and Western blot results indicated that Dex caused up-regulation of human ACAT1 expression at both the mRNA and protein levels in THP-1 and THP- 1-derived macrophages. The luciferase activity assay demonstrated that Dex could enhance the activity of human ACAT1 gene P1 promoter, a major factor leading to the ACAT1 activation, in a cell-specific manner.Further experimental evidences showed that a glucocorticoid response element (GRE) located within human ACAT1gene P1 promoter to response to the elevation of human ACAT1 gene expression by Dex could be functionally bound with glucocorticoid receptor (GR) proteins. These data supported the hypothesis that the clinical treatment with Dex,which increased the incidence of atherosclerosis, may in part due to enhancing the ACAT1 expression to promote the accumulation of cholesteryl esters during the macrophage-derived foam cell formation, an early stage of atherosclerosis.

  16. Cbln family proteins promote synapse formation by regulating distinct neurexin signaling pathways in various brain regions.

    Science.gov (United States)

    Matsuda, Keiko; Yuzaki, Michisuke

    2011-04-01

    Cbln1 (a.k.a. precerebellin) is a unique bidirectional synaptic organizer that plays an essential role in the formation and maintenance of excitatory synapses between granule cells and Purkinje cells in the mouse cerebellum. Cbln1 secreted from cerebellar granule cells directly induces presynaptic differentiation and indirectly serves as a postsynaptic organizer by binding to its receptor, the δ2 glutamate receptor. However, it remains unclear how Cbln1 binds to the presynaptic sites and interacts with other synaptic organizers. Furthermore, although Cbln1 and its family members Cbln2 and Cbln4 are expressed in brain regions other than the cerebellum, it is unknown whether they regulate synapse formation in these brain regions. In this study, we showed that Cbln1 and Cbln2, but not Cbln4, specifically bound to its presynaptic receptor -α and β isoforms of neurexin carrying the splice site 4 insert [NRXs(S4+)] - and induced synaptogenesis in cerebellar, hippocampal and cortical neurons in vitro. Cbln1 competed with synaptogenesis mediated by neuroligin 1, which lacks the splice sites A and B, but not leucine-rich repeat transmembrane protein 2, possibly by sharing the presynaptic receptor NRXs(S4+). However, unlike neurexins/neuroligins or neurexins/leucine-rich repeat transmembrane proteins, the interaction between NRX1β(S4+) and Cbln1 was insensitive to extracellular Ca(2+) concentrations. These findings revealed the unique and general roles of Cbln family proteins in mediating the formation and maintenance of synapses not only in the cerebellum but also in various other brain regions.

  17. A new behavior model for better understanding of titanium alloys Ti-6Al-4V chip formation in orthogonal cutting

    Science.gov (United States)

    Harzallah, M.; Pottier, T.; Senatore, J.; Mousseigne, M.; Germain, G.; Landon, Y.

    2016-10-01

    The behavior of Ti-6Al-4V has been studied via shear tests, using hat shaped specimen, on a servo-hydraulic Gleeble 3800 testing machine under the strain rate up to 103s-1and temperature up to 900°C. A new thermo-visco-plastic material law is proposed, based on a modified Johnson-Cook formulation. An inverse identification method based on Finite Element (FE) is established and detailed in order to determine the constitutive law's parameters. The new model is implemented in a 3D finite element model to study the chip formation in orthogonal cutting configuration. The numerical simulations were performed on FE software Impetus Afea® able to solve dynamic non-linear problem.

  18. Formation Process of Triangular Morphology of Self-Accommodation Martensite in Ti-Nb-Al Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Kamioka Nozomi

    2015-01-01

    Full Text Available The formation process of a habit plane variant (HPV cluster with triangular morphology (T-cluster in Ti- Nb-Al shape memory alloy was investigated by in-situ optical microscopy. Upon cooling the specimen, martensitic transformation occurred and two types of V-shaped clusters and the T-clusters were observed. Two types of V-shaped cluster were the cluster connected by the {111} type I twin (VI and the cluster connected by the type II twin (VII. The T-cluster is formed by the connection of three HPVs by {111} type I twin. The T-cluster is formed by the growth of the third HPV that is nucleated at the tip of a HPV in a VI-cluster and exhibits inward growth. It is suggested that the T-cluster is a derivative of the VI-cluster. This growth behaviour is discussed based on the incompatibility of the clusters.

  19. PROMOVER (PROMOTE) - A participative methodology in socio-environmental project formation and management

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Edison; Danciguer, Lucilene; Virginio, Geraldo; Del Carlo, Sylene

    2010-09-15

    We present a program's findings in socio-environmental sustainable development (PROMOVER), implemented by GAIA/Shell Brasil partnership. Benefited communities were leaders in artisanal fisher communities, governmental and non-governmental organizations within Shell influence areas, at Rio de Janeiro and Espirito Santo states, Brazil. The main objective is to improve its economic activities in sustainable way. The program consisted of formation on socio-environmental project elaboration, follow-up and seminar presentation. It was an interactive and dynamic training, in which leaders discussed the importance of social entrepreneurship, citizen organizations, and the establishment of networks aimed to sustainable development. Community leaders concluded 10 projects, one was awarded.

  20. Natural products for treatment of osteoporosis: The effects and mechanisms on promoting osteoblast-mediated bone formation.

    Science.gov (United States)

    An, Jing; Yang, Hao; Zhang, Qian; Liu, Cuicui; Zhao, Jingjing; Zhang, Lingling; Chen, Bo

    2016-02-15

    Osteoporosis is a systemic metabolic bone disease characterized by a reduction in bone mass, bone quality, and microarchitectural deterioration. An imbalance in bone remodeling that is caused by more osteoclast-mediated bone resorption than osteoblast-mediated bone formation results in such pathologic bone disorder. Traditional Chinese medicines (TCM) have long been used to prevent and treat osteoporosis and have received extensive attentions and researches at home and abroad, because they have fewer adverse reactions and are more suitable for long-term use compared with chemically synthesized medicines. Here, we put the emphasis on osteoblasts, summarized the detailed research progress on the active compounds derived from TCM with potential anti-osteoporosis effects and their molecular mechanisms on promoting osteoblast-mediated bone formation. It could be concluded that TCM with kidney-tonifying, spleen-tonifying, and stasis-removing effects all have the potential effects on treating osteoporosis. The active ingredients derived from TCM that possess effects on promoting osteoblasts proliferation and differentiation include flavonoids, glycosides, coumarins, terpenoids (sesquiterpenoids, monoterpenoids, diterpenoids), phenolic acids, phenols and others (tetrameric stilbene, anthraquinones, diarylheptanoids). And it was confirmed that the bone formation effect induced by the above natural products was regulated by the expressions of bone specific matrix proteins (ALP, BSP, OCN, OPN, COL I), transcription factor (Runx2, Cbfa1, Osx), signal pathways (MAPK, BMP), local factors (ROS, NO), OPG/RANKL system of osteoblasts and estrogen-like biological activities. All the studies provided theoretical basis for clinical application, as well as new drug research and development on treating osteoporosis.

  1. Prophage spontaneous activation promotes DNA release enhancing biofilm formation in Streptococcus pneumoniae.

    Directory of Open Access Journals (Sweden)

    Margarida Carrolo

    Full Text Available Streptococcus pneumoniae (pneumococcus is able to form biofilms in vivo and previous studies propose that pneumococcal biofilms play a relevant role both in colonization and infection. Additionally, pneumococci recovered from human infections are characterized by a high prevalence of lysogenic bacteriophages (phages residing quiescently in their host chromosome. We investigated a possible link between lysogeny and biofilm formation. Considering that extracellular DNA (eDNA is a key factor in the biofilm matrix, we reasoned that prophage spontaneous activation with the consequent bacterial host lysis could provide a source of eDNA, enhancing pneumococcal biofilm development. Monitoring biofilm growth of lysogenic and non-lysogenic pneumococcal strains indicated that phage-infected bacteria are more proficient at forming biofilms, that is their biofilms are characterized by a higher biomass and cell viability. The presence of phage particles throughout the lysogenic strains biofilm development implicated prophage spontaneous induction in this effect. Analysis of lysogens deficient for phage lysin and the bacterial major autolysin revealed that the absence of either lytic activity impaired biofilm development and the addition of DNA restored the ability of mutant strains to form robust biofilms. These findings establish that limited phage-mediated host lysis of a fraction of the bacterial population, due to spontaneous phage induction, constitutes an important source of eDNA for the S. pneumoniae biofilm matrix and that this localized release of eDNA favors biofilm formation by the remaining bacterial population.

  2. Syndapin promotes pseudocleavage furrow formation by actin organization in the syncytial Drosophila embryo.

    Science.gov (United States)

    Sherlekar, Aparna; Rikhy, Richa

    2016-07-01

    Coordinated membrane and cytoskeletal remodeling activities are required for membrane extension in processes such as cytokinesis and syncytial nuclear division cycles in Drosophila Pseudocleavage furrow membranes in the syncytial Drosophila blastoderm embryo show rapid extension and retraction regulated by actin-remodeling proteins. The F-BAR domain protein Syndapin (Synd) is involved in membrane tubulation, endocytosis, and, uniquely, in F-actin stability. Here we report a role for Synd in actin-regulated pseudocleavage furrow formation. Synd localized to these furrows, and its loss resulted in short, disorganized furrows. Synd presence was important for the recruitment of the septin Peanut and distribution of Diaphanous and F-actin at furrows. Synd and Peanut were both absent in furrow-initiation mutants of RhoGEF2 and Diaphanous and in furrow-progression mutants of Anillin. Synd overexpression in rhogef2 mutants reversed its furrow-extension phenotypes, Peanut and Diaphanous recruitment, and F-actin organization. We conclude that Synd plays an important role in pseudocleavage furrow extension, and this role is also likely to be crucial in cleavage furrow formation during cell division.

  3. Ectopic bone formation by 3D porous calcium phosphate-Ti6Al4V hybrids produced by perfusion electrodeposition.

    Science.gov (United States)

    Chai, Yoke Chin; Kerckhofs, Greet; Roberts, Scott J; Van Bael, Simon; Schepers, Evert; Vleugels, Jozef; Luyten, Frank P; Schrooten, Jan

    2012-06-01

    Successful clinical repair of non-healing skeletal defects requires the use of bone substitutes with robust bone inductivity and excellent biomechanical stability. Thus, three-dimensionally functionalised porous calcium phosphate-Ti6Al4V (CaP-Ti) hybrids were produced by perfusion electrodeposition, and the in vitro and in vivo biological performances were evaluated using human periosteum derived cells (hPDCs). By applying various current densities at the optimised deposition conditions, CaP coatings with sub-micrometer to nano-scale porous crystalline structures and different ion dissolution kinetics were deposited on the porous Ti6Al4V scaffolds. These distinctive physicochemical properties caused a significant impact on in vitro proliferation, osteogenic differentiation, and matrix mineralisation of hPDCs. This includes a potential role of hPDCs in mediating osteoclastogenesis for the resorption of CaP coatings, as indicated by a significant down-regulation of osteoprotegerin (OPG) gene expression and by the histological observation of abundant multi-nucleated giant cells near to the coatings. By subcutaneous implantation, the produced hybrids induced ectopic bone formation, which was highly dependent on the physicochemical properties of the CaP coating (including the Ca(2+) dissolution kinetics and coating surface topography), in a cell density-dependent manner. This study provided further insight on stem cell-CaP biomaterial interactions, and the feasibility to produced bone reparative units that are predictively osteoinductive in vivo by perfusion electrodeposition technology.

  4. An Exploration of Teachers' Narratives: What Are the Facilitators and Constraints Which Promote or Inhibit "Good" Formative Assessment Practices in Schools?

    Science.gov (United States)

    Sach, Elizabeth

    2015-01-01

    This paper set out to explore teachers' narratives in order to understand some of the facilitators and constraints which promote or inhibit good formative assessment practices in schools. A "responsive interview" approach was used to probe a small sample of lower and middle school teachers' perceptions of formative assessment.…

  5. Wnt3a Promotes the Vasculogenic Mimicry Formation of Colon Cancer via Wnt/β-Catenin Signaling.

    Science.gov (United States)

    Qi, Lisha; Song, Wangzhao; Liu, Zhiyong; Zhao, Xiulan; Cao, Wenfeng; Sun, Baocun

    2015-08-10

    Our previous study provided evidence that non-canonical Wnt signaling is involved in regulating vasculogenic mimicry (VM) formation. However, the functions of canonical Wnt signaling in VM formation have not yet been explored. In this study, we found the presence of VM was related to colon cancer histological differentiation (p colon cancer samples showed increased Wnt3a expression (p colon cancer cells promoted the capacity to form tube-like structures in the three-dimensional (3-D) culture together with increased expression of endothelial phenotype-associated proteins such as VEGFR2 and VE-cadherin. The mouse xenograft model showed that Wnt3a-overexpressing cells grew into larger tumor masses and formed more VM than the control cells. In addition, the Wnt/β-catenin signaling antagonist Dickkopf-1(Dkk1) can reverse the capacity to form tube-like structures and can decrease the expressions of VEGFR2 and VE-cadherin in Wnt3a-overexpressing cells. Taken together, our results suggest that Wnt/β-catenin signaling is involved in VM formation in colon cancer and might contribute to the development of more accurate treatment modalities aimed at VM.

  6. Mg(2+)/Ca(2+) promotes the adhesion of marine bacteria and algae and enhances following biofilm formation in artificial seawater.

    Science.gov (United States)

    He, Xiaoyan; Wang, Jinpeng; Abdoli, Leila; Li, Hua

    2016-10-01

    Adhesion of microorganisms in the marine environment is essential for initiation and following development of biofouling. A variety of factors play roles in regulating the adhesion. Here we report the influence of Ca(2+) and Mg(2+) in artificial seawater on attachment and colonization of Bacillus sp., Chlorella and Phaeodactylum tricornutum on silicon wafer. Extra addition of the typical divalent cations in culturing solution gives rise to significantly enhanced adhesion of the microorganisms. Mg(2+) and Ca(2+) affect the adhesion of Bacillus sp. presumably by regulating aggregation and formation of extracellular polymeric substances (EPS). The ions alter quantity and types of the proteins in EPS, in turn affecting subsequent adhesion. However, it is noted that Mg(2+) promotes adhesion of Chlorella likely by regulating EPS formation and polysaccharide synthesis. Ca(2+) plays an important role in protein expression to enhance the adhesion of Chlorella. For Phaeodactylum tricornutum, Ca(2+) expedites protein synthesis for enhanced adhesion. The results shed some light on effective ways of utilizing divalent cations to mediate formation of biofilms on the marine structures for desired performances.

  7. Septins promote F-actin ring formation by crosslinking actin filaments into curved bundles.

    Science.gov (United States)

    Mavrakis, Manos; Azou-Gros, Yannick; Tsai, Feng-Ching; Alvarado, José; Bertin, Aurélie; Iv, Francois; Kress, Alla; Brasselet, Sophie; Koenderink, Gijsje H; Lecuit, Thomas

    2014-04-01

    Animal cell cytokinesis requires a contractile ring of crosslinked actin filaments and myosin motors. How contractile rings form and are stabilized in dividing cells remains unclear. We address this problem by focusing on septins, highly conserved proteins in eukaryotes whose precise contribution to cytokinesis remains elusive. We use the cleavage of the Drosophila melanogaster embryo as a model system, where contractile actin rings drive constriction of invaginating membranes to produce an epithelium in a manner akin to cell division. In vivo functional studies show that septins are required for generating curved and tightly packed actin filament networks. In vitro reconstitution assays show that septins alone bundle actin filaments into rings, accounting for the defects in actin ring formation in septin mutants. The bundling and bending activities are conserved for human septins, and highlight unique functions of septins in the organization of contractile actomyosin rings.

  8. Zinc promotes clot stability by accelerating clot formation and modifying fibrin structure.

    Science.gov (United States)

    Henderson, Sara J; Xia, Jing; Wu, Huayin; Stafford, Alan R; Leslie, Beverly A; Fredenburgh, James C; Weitz, David A; Weitz, Jeffrey I

    2016-03-01

    Zinc released from activated platelets binds fibrin(ogen) and attenuates fibrinolysis. Although zinc also affects clot formation, the mechanism and consequences are poorly understood. To address these gaps, the effect of zinc on clot formation and structure was examined in the absence or presence of factor (F) XIII. Zinc accelerated a) plasma clotting by 1.4-fold, b) fibrinogen clotting by 3.5- and 2.3-fold in the absence or presence of FXIII, respectively, c) fragment X clotting by 1.3-fold, and d) polymerisation of fibrin monomers generated with thrombin or batroxobin by 2.5- and 1.8-fold, respectively. Whereas absorbance increased up to 3.3-fold when fibrinogen was clotted in the presence of zinc, absorbance of fragment X clots was unaffected by zinc, consistent with reports that zinc binds to the αC-domain of fibrin(ogen). Scanning electron microscopic analysis revealed a two-fold increase in fibre diameter in the presence of zinc and in permeability studies, zinc increased clot porosity by 30-fold with or without FXIII. Whereas FXIII increased clot stiffness from 128 ± 19 Pa to 415 ± 27 Pa in rheological analyses, zinc reduced clot stiffness by 10- and 8.5-fold in the absence and presence of FXIII, respectively. Clots formed in the presence of zinc were more stable and resisted rupture with or without FXIII. Therefore, zinc accelerates clotting and reduces fibrin clot stiffness in a FXIII-independent manner, suggesting that zinc may work in concert with FXIII to modulate clot strength and stability.

  9. Respiratory syncytial virus fusion protein promotes TLR-4-dependent neutrophil extracellular trap formation by human neutrophils.

    Directory of Open Access Journals (Sweden)

    Giselle A Funchal

    Full Text Available Acute viral bronchiolitis by Respiratory Syncytial Virus (RSV is the most common respiratory illness in children in the first year of life. RSV bronchiolitis generates large numbers of hospitalizations and an important burden to health systems. Neutrophils and their products are present in the airways of RSV-infected patients who developed increased lung disease. Neutrophil Extracellular Traps (NETs are formed by the release of granular and nuclear contents of neutrophils in the extracellular space in response to different stimuli and recent studies have proposed a role for NETs in viral infections. In this study, we show that RSV particles and RSV Fusion protein were both capable of inducing NET formation by human neutrophils. Moreover, we analyzed the mechanisms involved in RSV Fusion protein-induced NET formation. RSV F protein was able to induce NET release in a concentration-dependent fashion with both neutrophil elastase and myeloperoxidase expressed on DNA fibers and F protein-induced NETs was dismantled by DNase treatment, confirming that their backbone is chromatin. This viral protein caused the release of extracellular DNA dependent on TLR-4 activation, NADPH Oxidase-derived ROS production and ERK and p38 MAPK phosphorylation. Together, these results demonstrate a coordinated signaling pathway activated by F protein that led to NET production. The massive production of NETs in RSV infection could aggravate the inflammatory symptoms of the infection in young children and babies. We propose that targeting the binding of TLR-4 by F protein could potentially lead to novel therapeutic approaches to help control RSV-induced inflammatory consequences and pathology of viral bronchiolitis.

  10. Pyruvate kinase M2 activators promote tetramer formation and suppress tumorigenesis

    Energy Technology Data Exchange (ETDEWEB)

    Anastasiou, Dimitrios; Yu, Yimin; Israelsen, William J.; Jiang, Jian-Kang; Boxer, Matthew B.; Hong, Bum Soo; Tempel, Wolfram; Dimov, Svetoslav; Shen, Min; Jha, Abhishek; Yang, Hua; Mattaini, Katherine R.; Metallo, Christian M.; Fiske, Brian P.; Courtney, Kevin D.; Malstrom, Scott; Khan, Tahsin M.; Kung, Charles; Skoumbourdis, Amanda P.; Veith, Henrike; Southall, Noel; Walsh, Martin J.; Brimacombe, Kyle R.; Leister, William; Lunt, Sophia Y.; Johnson, Zachary R.; Yen, Katharine E.; Kunii, Kaiko; Davidson, Shawn M.; Christofk, Heather R.; Austin, Christopher P.; Inglese, James; Harris, Marian H.; Asara, John M.; Stephanopoulos, Gregory; Salituro, Francesco G.; Jin, Shengfang; Dang, Lenny; Auld, Douglas S.; Park, Hee-Won; Cantley, Lewis C.; Thomas, Craig J.; Vander Heiden, Matthew G.

    2012-08-26

    Cancer cells engage in a metabolic program to enhance biosynthesis and support cell proliferation. The regulatory properties of pyruvate kinase M2 (PKM2) influence altered glucose metabolism in cancer. The interaction of PKM2 with phosphotyrosine-containing proteins inhibits enzyme activity and increases the availability of glycolytic metabolites to support cell proliferation. This suggests that high pyruvate kinase activity may suppress tumor growth. We show that expression of PKM1, the pyruvate kinase isoform with high constitutive activity, or exposure to published small-molecule PKM2 activators inhibits the growth of xenograft tumors. Structural studies reveal that small-molecule activators bind PKM2 at the subunit interaction interface, a site that is distinct from that of the endogenous activator fructose-1,6-bisphosphate (FBP). However, unlike FBP, binding of activators to PKM2 promotes a constitutively active enzyme state that is resistant to inhibition by tyrosine-phosphorylated proteins. This data supports the notion that small-molecule activation of PKM2 can interfere with anabolic metabolism.

  11. TSR promotes the formation of oil-cracking gases: Evidence from simulation experiments

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    TSR is an interaction between sulfate and hydrocarbons, occurring widely in carbonate reservoirs. Because this process can produce a large amount of noxious acidic gases like H2S, it has drawn seri- ous concern recently. This paper reports an experiment that simulated an interaction between different minerals and hydrocarbon fluids under different temperature and time using a confined gold-tube system. The results showed that the main mineral that initiates TSR is MgSO4, and adding a certain amount of NaCl into the reactive system can also promote TSR and yield more H2S. The H2S produced in TSR is an important incentive for the continuous oxidative degradation of crude oils. For instance, the yield of oil-cracking gases affected by TSR was twice of that not affected by TSR while the yield of TSR-affected methane was even higher, up to three times of that unaffected by TSR. The carbon iso- topes of wet gases also became heavier. All of the above illustrated that TSR obviously motivates the oxidative degradation of crude oils, which makes the gaseous hydrocarbon generation sooner and increases the gas dryness as well. The study on this process is important for understanding the TSR mechanism and the mechanism of natural gas generation in marine strata.

  12. Silicon-Doped Titanium Dioxide Nanotubes Promoted Bone Formation on Titanium Implants.

    Science.gov (United States)

    Zhao, Xijiang; Wang, Tao; Qian, Shi; Liu, Xuanyong; Sun, Junying; Li, Bin

    2016-02-26

    While titanium (Ti) implants have been extensively used in orthopaedic and dental applications, the intrinsic bioinertness of untreated Ti surface usually results in insufficient osseointegration irrespective of the excellent biocompatibility and mechanical properties of it. In this study, we prepared surface modified Ti substrates in which silicon (Si) was doped into the titanium dioxide (TiO₂) nanotubes on Ti surface using plasma immersion ion implantation (PIII) technology. Compared to TiO₂ nanotubes and Ti alone, Si-doped TiO₂ nanotubes significantly enhanced the expression of genes related to osteogenic differentiation, including Col-I, ALP, Runx2, OCN, and OPN, in mouse pre-osteoblastic MC3T3-E1 cells and deposition of mineral matrix. In vivo, the pull-out mechanical tests after two weeks of implantation in rat femur showed that Si-doped TiO₂ nanotubes improved implant fixation strength by 18% and 54% compared to TiO₂-NT and Ti implants, respectively. Together, findings from this study indicate that Si-doped TiO₂ nanotubes promoted the osteogenic differentiation of osteoblastic cells and improved bone-Ti integration. Therefore, they may have considerable potential for the bioactive surface modification of Ti implants.

  13. Calcium carbonate hybrid coating promotes the formation of biomimetic hydroxyapatite on titanium surfaces

    Science.gov (United States)

    Cruz, Marcos Antônio E.; Ruiz, Gilia C. M.; Faria, Amanda N.; Zancanela, Daniela C.; Pereira, Lourivaldo S.; Ciancaglini, Pietro; Ramos, Ana P.

    2016-05-01

    CaCO3 particles dispersed in liquid media have proven to be good inductors of hydroxyapatite (HAp) growth. However, the use of CaCO3 deposited as thin films for this propose is unknown. Here, we report the growth of CaCO3 continuous films on Langmuir-Blodgett (LB) modified titanium surfaces and its use as HAp growth inductor. The Ti surfaces were modified with two, four, and six layers of dihexadecylphosphate (DHP)-LB films containing Ca2+, exposed to CO2 (g) for 12 h. The modified surfaces were immersed in simulated body fluid (SBF) at 37 °C for 36 h and submitted to bioactivity studies. This procedure originates bioactive coatings composed by non-stoichiometric HAp as evidenced by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The presence of the CaCO3 film as pre-coating diminished the time necessary to growth continuous and homogeneous HAp films using a biomimetic approach. The surface properties of the films regarding their roughness, composition, charge, wettability, and surface free energy (γs) were accessed. The presence of HAp increased the wettability and γs of the surfaces. The coatings are not toxic for osteoblasts as observed for cell viability assays obtained after 7 and 14 days of culture. Moreover, the CaCO3 thin films promote the recovery of the osteoblasts viability more than the Ti surfaces themselves.

  14. Kyanite Formation and Element Fractionation in the High-Al Eclogites from the Sulu UHP Metamorphic Terrane

    Directory of Open Access Journals (Sweden)

    Yung-Hsin Liu

    2010-01-01

    Full Text Available Eclogite compositions are critical parameters for under standing chemical evolution in the Earth, particularly in subduction zones. A group of eclogites from the Sulu ultra-high pres sure (UHP metamorphic terrane in eastern China shows uncommon petrographic and compositional features. They are characterized by (1 zoisite porphyroblasts coexisting with inclusion-free, inclusion-containing, and net work kyanite, (2 high Al2O3 of 18.4 - 29.2% with high MgO of 8.59 - 11.3%, and (3 intensive HFSE-REE fractionations represented by [Zr/Sm]ch and [Ti/Gd]ch ratios of 0.1 - 3.9 and 1.1 - 9.0, respectively. High-pressure fluids played a major role on developing these features. Kyanite shows two textural varieties. KyI is inclusion-free and in apparent textural equilibrium with gar net and omphacite, implying formation from plagioclase break down. KyII includes kyanite networks and porphyroblasts; the former occurs mostly in gar net, whereas the latter encloses gar net and omphacite grains. KyII were crystallized at the expense of gar net and omphacite during eclogite-fluid interaction. The low [HREE]ch ratios of 1 - 2 indicate that the protoliths were arc cumulates. The well-de fined in verse Al2O3-SiO2 and Al2O3-CaO correlations are not the characteristics of igneous precursors; there fore, must reflect metamorphic modifications. The comparison to mafic cumulates shows that the low-Al samples are compositionally better representatives of protoliths. Mass balance calculations point to anolivine gabbronoritic protolith. The intensive HFSE-REE fractionations reflect compositional differences between two sample groups. Group I samples have superchondritic HFSE-REE ratios [(Nb/La, Zr/Sm, Ti/Gdch = 2 - 7] with depletions in LREE. In contrast, group II samples show HFSE depletions and LREE enrichments. These compositional differences were explained as reflecting element mobility during eclogite-fluid inter action. Released at temperatures > _ the high-pres sure

  15. Mesenchymal Wnt signaling promotes formation of sternum and thoracic body wall.

    Science.gov (United States)

    Snowball, John; Ambalavanan, Manoj; Cornett, Bridget; Lang, Richard; Whitsett, Jeffrey; Sinner, Debora

    2015-05-15

    Midline defects account for approximately 5% of congenital abnormalities observed at birth. However, the molecular mechanisms underlying the formation of the ventral body wall are not well understood. Recent studies linked mutations in Porcupine-an O-acetyl transferase mediating Wnt ligand acylation-with defects in the thoracic body wall. We hypothesized that anomalous Wnt signaling is involved in the pathogenesis of defective closure of the thoracic body wall. We generated a mouse model wherein Wntless (Wls), which encodes a cargo receptor mediating secretion of Wnt ligands, was conditionally deleted from the developing mesenchyme using Dermo1Cre mice. Wls(f/f);Dermo1(Cre/+) embryos died during mid-gestation. At E13.5, skeletal defects were observed in the forelimbs, jaw, and rib cage. At E14.5, midline defects in the thoracic body wall began to emerge: the sternum failed to fuse and the heart protruded through the body wall at the midline (ectopia cordis). To determine the molecular mechanism underlying the phenotype observed in Wls(f/f);Dermo1(Cre/+) embryos, we tested whether Wnt/β-catenin signaling was operative in developing the embryonic ventral body wall using Axin2(LacZ) and BatGal reporter mice. While Wnt/β-catenin signaling activity was observed at the midline of the ventral body wall before sternal fusion, this pattern of activity was altered and scattered throughout the body wall after mesenchymal deletion of Wls. Mesenchymal cell migration was disrupted in Wls(f/f);Dermo1(Cre/+) thoracic body wall partially due to anomalous β-catenin independent Wnt signaling as determined by in vitro assays. Deletion of Lrp5 and Lrp6 receptors, which mediate Wnt/β-catenin signaling in the mesenchyme, partially recapitulated the phenotype observed in the chest midline of Wls(f/f);Dermo1(Cre/+) embryos supporting a role for Wnt/β-catenin signaling activity in the normal formation of the ventral body wall mesenchyme. We conclude that Wls-mediated secretion of Wnt

  16. Influence of excess sodium ions on the specific surface area formation in a NiO-Al2O3 catalyst prepared by different methods

    Directory of Open Access Journals (Sweden)

    Lazić M.M.

    2008-01-01

    Full Text Available The influence of sodium ions on the specific surface area of a NiO-Al2O3 catalyst in dependence of nickel loading (5, 10, and 20 wt% Ni, temperature of heat treatment (400, 700 and 1100oC and the method of sample preparation was investigated. Low temperature nitrogen adsorption (LTNA, X-ray diffraction (XRD and scanning electron microscopy (SEM were applied for sample characterization. Dramatic differences in the specific surface area were registered between non-rinsed and rinsed Al2O3 and NiO-Al2O3 samples. The lagged sodium ions promote sintering of non-rinsed catalyst samples.

  17. Calcium carbonate hybrid coating promotes the formation of biomimetic hydroxyapatite on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Marcos Antônio E.; Ruiz, Gilia C.M. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Faria, Amanda N. [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Departamento de Bioquímica e Imunologia-Faculdade de Medicina de Ribeirão Preto Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Zancanela, Daniela C.; Pereira, Lourivaldo S.; Ciancaglini, Pietro [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil); Ramos, Ana P., E-mail: anapr@ffclrp.usp.br [Departamento de Química-Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, SP (Brazil)

    2016-05-01

    Graphical abstract: - Highlights: • CaCO{sub 3} continuous films were deposited on titanium discs using a biomimetic approach. • The coatings origin hydroxyapatite when immersed in simulated body fluid. • The wettability and the free energy of the surfaces were increased after the treatment. • The coated titanium discs are bioactive and non-toxic to osteoblasts. - Abstract: CaCO{sub 3} particles dispersed in liquid media have proven to be good inductors of hydroxyapatite (HAp) growth. However, the use of CaCO{sub 3} deposited as thin films for this propose is unknown. Here, we report the growth of CaCO{sub 3} continuous films on Langmuir–Blodgett (LB) modified titanium surfaces and its use as HAp growth inductor. The Ti surfaces were modified with two, four, and six layers of dihexadecylphosphate (DHP)-LB films containing Ca{sup 2+}, exposed to CO{sub 2} (g) for 12 h. The modified surfaces were immersed in simulated body fluid (SBF) at 37 °C for 36 h and submitted to bioactivity studies. This procedure originates bioactive coatings composed by non-stoichiometric HAp as evidenced by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). The presence of the CaCO{sub 3} film as pre-coating diminished the time necessary to growth continuous and homogeneous HAp films using a biomimetic approach. The surface properties of the films regarding their roughness, composition, charge, wettability, and surface free energy (γ{sub s}) were accessed. The presence of HAp increased the wettability and γ{sub s} of the surfaces. The coatings are not toxic for osteoblasts as observed for cell viability assays obtained after 7 and 14 days of culture. Moreover, the CaCO{sub 3} thin films promote the recovery of the osteoblasts viability more than the Ti surfaces themselves.

  18. Putative DNA G-quadruplex formation within the promoters of Plasmodium falciparum var genes

    Directory of Open Access Journals (Sweden)

    Rowe J

    2009-08-01

    Full Text Available Abstract Background Guanine-rich nucleic acid sequences are capable of folding into an intramolecular four-stranded structure called a G-quadruplex. When found in gene promoter regions, G-quadruplexes can downregulate gene expression, possibly by blocking the transcriptional machinery. Here we have used a genome-wide bioinformatic approach to identify Putative G-Quadruplex Sequences (PQS in the Plasmodium falciparum genome, along with biophysical techniques to examine the physiological stability of P. falciparum PQS in vitro. Results We identified 63 PQS in the non-telomeric regions of the P. falciparum clone 3D7. Interestingly, 16 of these PQS occurred in the upstream region of a subset of the P. falciparum var genes (group B var genes. The var gene family encodes PfEMP1, the parasite's major variant antigen and adhesin expressed at the surface of infected erythrocytes, that plays a key role in malaria pathogenesis and immune evasion. The ability of the PQS found in the upstream regions of group B var genes (UpsB-Q to form stable G-quadruplex structures in vitro was confirmed using 1H NMR, circular dichroism, UV spectroscopy, and thermal denaturation experiments. Moreover, the synthetic compound BOQ1 that shows a higher affinity for DNA forming quadruplex rather than duplex structures was found to bind with high affinity to the UpsB-Q. Conclusion This is the first demonstration of non-telomeric PQS in the genome of P. falciparum that form stable G-quadruplexes under physiological conditions in vitro. These results allow the generation of a novel hypothesis that the G-quadruplex sequences in the upstream regions of var genes have the potential to play a role in the transcriptional control of this major virulence-associated multi-gene family.

  19. The Gαo Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons

    Directory of Open Access Journals (Sweden)

    Valerie T. Ramírez

    2016-01-01

    Full Text Available Mastoparan-7 (Mas-7, an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX- sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95 clustering in neurites and activates Gαo signaling, increasing the intracellular Ca2+ concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC, c-Jun N-terminal kinase (JNK, and calcium-calmodulin dependent protein kinase IIα (CaMKIIα after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gαo subunit signaling in the regulation of synapse formation.

  20. The Gαo Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons

    Science.gov (United States)

    Ramírez, Valerie T.; Ramos-Fernández, Eva; Inestrosa, Nibaldo C.

    2016-01-01

    Mastoparan-7 (Mas-7), an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX-) sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95) clustering in neurites and activates Gαo signaling, increasing the intracellular Ca2+ concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC), c-Jun N-terminal kinase (JNK), and calcium-calmodulin dependent protein kinase IIα (CaMKIIα) after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gαo subunit signaling in the regulation of synapse formation. PMID:26881110

  1. CD147 promotes the formation of functional osteoclasts through NFATc1 signalling.

    Science.gov (United States)

    Nishioku, Tsuyoshi; Terasawa, Mariko; Baba, Misaki; Yamauchi, Atsushi; Kataoka, Yasufumi

    2016-04-29

    CD147, a membrane glycoprotein of the immunoglobulin superfamily, is highly upregulated during dynamic cellular events including tissue remodelling. Elevated CD147 expression is present in the joint of rheumatoid arthritis patients. However, the role of CD147 in bone destruction remains unclear. To determine whether CD147 is involved in osteoclastogenesis, we studied its expression in mouse osteoclasts and its role in osteoclast differentiation and function. CD147 expression was markedly upregulated during osteoclast differentiation. To investigate the role of CD147 in receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclastogenesis and bone resorption activity, osteoclast precursor cells were transfected with CD147 siRNA. Decreased CD147 expression inhibited osteoclast formation and bone resorption, inhibited RANKL-induced nuclear translocation of the nuclear factor of activated T cells (NFAT) c1 and decreased the expression of the d2 isoform of vacuolar ATPase Vo domain and cathepsin K. Therefore, CD147 plays a critical role in the differentiation and function of osteoclasts by upregulating NFATc1 through the autoamplification of its expression in osteoclastogenesis.

  2. Studies of the structure and function of Mms6, a bacterial protein that promotes the formation of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijun [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Here we report structural and functional studies of Mms6, a biomineralization protein that can promote the formation in vitro of magnetic nanoparticles with sizes and morphologies similar to the magnetites synthesized by magnetotactic bacteria. We found the binding pattern of Mms6 to ferric ion to be two-phase and multivalent. We quantatively determined that Mms6 binds one Fe3+ with a very high affinity (Kd = 1016 M). The second phase of iron binding is multivalent and cooperative with respect to iron with a Kd in the μM range and a stoichiometry of about 20 ferric ion per protein molecule. We found that Mms6 exists in large particles of two sizes, one consisting of 20-40 monomeric units and the other of 200 units. From proteolytic digestion, ultracentrifugation and liposome fusion studies, we found that Mms6 forms a large micellar quaternary structure with the N-terminal domain self-assembling into a uniformly sized micelle and the C-terminal domain on the surface. The two-phase iron-binding pattern may be relevant to iron crystal formation. We propose that the first high affinity phase may stabilize a new conformation of the C-terminal domain that allows interaction with other C-terminal domains leading to a structural change in the multimeric protein complex that enables the second low affinity iron binding phase to organize iron and initiate crystal formation. We also observed a dimeric apparent molecular mass of the Mms6 C-terminal peptide (C21Mms6). We speculate that the C-terminal domain may form higher order quaternary arrangements on the surface of the micelle or when anchored to a membrane by the N-terminal domain. The change in fluorescence quenching in the N-terminal domain with iron binding suggests a structural integrity between the C- and N-terminal domains. The slow change in trp fluorescence as a function of time after adding iron suggests a very slow conformational change in the protein that involves

  3. Zurek-Kibble mechanism for the spontaneous vortex formation in Nb-Al/Al-ox/Nb Josephson tunnel junctions: New theory and experiment

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Aarøe, Morten

    2006-01-01

    New scaling behavior has been both predicted and observed in the spontaneous production of fluxons in quenched Nb-Al/Al-ox/Nb annular Josephson tunnel junctions (JTJs) as a function of the quench time, tau(Q). The probability f(1) to trap a single defect during the normal-metal-superconductor pha...

  4. A simple and effective approach for treatment of situs tumor and metastasis:to promote intratumor pus formation

    Directory of Open Access Journals (Sweden)

    Hong Li

    2015-12-01

    Full Text Available Purpose: The recent emergence of the tumor microenvironment as the critical determinant in cancer outcome opens a new routes to fight cancer, however, the clinical results of targeting microenvironment for treating human cancer have not met expectations. Our purpose is to investigate how to target microenvironment for treatment of situs tumor and metastasis.Methods : We suppose that tumor is a robber from times of anarchy and disorder and can be eradicated in flourishing age. We also suppose that carcinogenesis is largely attributed to physically weak that cann’t get rid of ulcer by pus formation. In vivo,the subcutaneous implant model and pulmonary metastasis model of lewis lung cancer were established. Tumor bearing mice were taken water decoction of Astragalus mongholicus(huangqi and Spina Gleditsiae (zaojiaoci by intragastric administration b.i.d for ten weeks, and the influences of Astragalus mongholicus and Spina Gleditsiae  on tumor progression were evaluated by body temperature,blood oxygen saturation,red cell ATPase,blood  rheology,intratumor hypoxia,capillary permeability, matrix metalloproteinase (MMPs and intratumor pus formation.  Results:We found that both of Astragalus mongholicus and Spina Gleditsiae could keep body temperature,blood oxygen saturation,red cell ATPase and blood rheology,and improve intratumor hypoxia,capillary permeability and MMPs in tumor bearing mice,which led to slower tumor growth and less metastasis. Astragalus mongholicus could remove body poison and stimulate immune responses, and Spina Gleditsiae  could  promote pus formation and proteolytic enzymes. The combination of  Astragalus mongholicus and Spina Gleditsiae favored the restoration of tumor immune responses and proteolytic activity at the tumor site, which not only result to an increase in aseptic pus formation, but also to a decrease in necrotic tissue accumulation, and finally caused a complete intratumor pus

  5. Formation of CaO·TiO2-MgO·Al2O3 dual phase inclusion in Ti stabilized stainless steel

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The formation of CaO.TiO2-MgO.Al2O3 dual phase inclusion in 321 stainless steel was investigated in the laboratory. The result indicated that the condition for the formation of CaO.TiO2-MgO.Al2O3 in 321 steel is [Ca]>0.001wt%, [Ti]>0.1wt%, and[Al]>0.01wt%. The mechanism is the following: Al2O3 inclusion turns into CaO-Al2O3 after Ca-Si wire is fed into the molten steel;[Mg] is then obtained by reducing MgO in slag or crucible wall by [Al] and [Ti]; finally CaO-Al2O3 inclusion is changed into CaO.TiO2-MgO-Al2O3 by the reaction with [Mg], [Ti], and [O] in the molten steel simultaneously.

  6. Optimum conditions for the formation of Al13 polymer and active chlorine in electrolysis process with Ti/RuO2-TiO2 anodes

    Institute of Scientific and Technical Information of China (English)

    Chengzhi Hu; Huijuan Liu; Jiuhui Qu

    2012-01-01

    A polyaluminum containing a high concentration of Al13 polymer and active chlorine (PACC) was successfully synthesized by a new electrochemical reactor using Ti/RuO2-TiO2 anodes.PACC can potentially be used as a dual-function chemical reagent for water treatment.The obtained results indicated that the formation of Al13 polymer and active chlorine,were the most active components in PACC responsible for coagulation and disinfection respectively.These components were significantly influenced by electrolyte temperature,current density,and stirring rate.It was observed that high electrolyte temperature favored the formation of Al13.Increasing current density and stirring rate resulted in high current efficiency of chlorine evolution,thus favoring the generation of Al13 and active chlorine in PACC.When the PACC (AlT =0.5 mol/L,basicity =2.3) was prepared at the optimum conditions by electrolysis process,the Al13 polymer and active chlorine in product reached above 70% of AlT and 4000 mg/L,respectively.In the pilot scale experiment with raw polyaluminum chloride used as an electrolyte,PACC was successfully prepared and produced a high content of Al13 and active chlorine products.The pilot scale experiment demonstrated a potential industrial approach of PACC preparation.

  7. High level of deoxycholic acid in human bile does not promote cholesterol gallstone formation

    Institute of Scientific and Technical Information of China (English)

    Ulf Gustafsson; Staffan Sahlin; Curt Einarsson

    2003-01-01

    AIM: To study whether patients with excess deoxycholic acid (DCA) differ from those with normal percentage of DCA with respect to biliary lipid composition and cholesterol saturation of gallbladder bile.METHODS: Bile was collected during operation through puncturing into the gallbladder from 122 cholesterol gallstone patients and 46 gallstone-free subjects undergoing cholecystectomy. Clinical data, biliary lipids, bile acid composition,presence of crystals and nucleation time were analyzed.RESULTS: A subgroup of gallstone patients displayeda higher proportion of DCA in bile than gallstone free subjects.By choosing a cut-off level of the 90th percentile, a group of 13 gallstone patients with high DCA levels (mean 50percent of total bile acids) and a large group of 109 patients with normal DCA levels (mean 21 percent of total bile acids)were obtained. The mean age of the patients with high DCA levels was higher than that of the group with normal levels (mean age: 62 years vs45 years) and so was the mean BMI (28.3 vs. 24.7). Plasma levels of cholesterol and triglycerides were slightly higher in the DCA excess groups compared with those in the normal DCA group. There was no difference in biliary lipid composition, cholesterol saturation, nucleation time or occurrence of cholesterol crystals in bile between patients with high and normal levels of DCA.CONCLUSION: Gallstone patients with excess DCA were of older age and had higher BMI than patients with normal DCA. The two groups of patients did not differ with respect to biliary lipid composition, cholesterol saturation, nucleation time or occurrence of cholesterol crystals. It is concluded that DCA in bile does not seem to contribute to gallstone formation in cholesterol gallstone patients.

  8. DNA ligase III promotes alternative nonhomologous end-joining during chromosomal translocation formation.

    Science.gov (United States)

    Simsek, Deniz; Brunet, Erika; Wong, Sunnie Yan-Wai; Katyal, Sachin; Gao, Yankun; McKinnon, Peter J; Lou, Jacqueline; Zhang, Lei; Li, James; Rebar, Edward J; Gregory, Philip D; Holmes, Michael C; Jasin, Maria

    2011-06-01

    Nonhomologous end-joining (NHEJ) is the primary DNA repair pathway thought to underlie chromosomal translocations and other genomic rearrangements in somatic cells. The canonical NHEJ pathway, including DNA ligase IV (Lig4), suppresses genomic instability and chromosomal translocations, leading to the notion that a poorly defined, alternative NHEJ (alt-NHEJ) pathway generates these rearrangements. Here, we investigate the DNA ligase requirement of chromosomal translocation formation in mouse cells. Mammals have two other DNA ligases, Lig1 and Lig3, in addition to Lig4. As deletion of Lig3 results in cellular lethality due to its requirement in mitochondria, we used recently developed cell lines deficient in nuclear Lig3 but rescued for mitochondrial DNA ligase activity. Further, zinc finger endonucleases were used to generate DNA breaks at endogenous loci to induce translocations. Unlike with Lig4 deficiency, which causes an increase in translocation frequency, translocations are reduced in frequency in the absence of Lig3. Residual translocations in Lig3-deficient cells do not show a bias toward use of pre-existing microhomology at the breakpoint junctions, unlike either wild-type or Lig4-deficient cells, consistent with the notion that alt-NHEJ is impaired with Lig3 loss. By contrast, Lig1 depletion in otherwise wild-type cells does not reduce translocations or affect microhomology use. However, translocations are further reduced in Lig3-deficient cells upon Lig1 knockdown, suggesting the existence of two alt-NHEJ pathways, one that is biased toward microhomology use and requires Lig3 and a back-up pathway which does not depend on microhomology and utilizes Lig1.

  9. DNA ligase III promotes alternative nonhomologous end-joining during chromosomal translocation formation.

    Directory of Open Access Journals (Sweden)

    Deniz Simsek

    2011-06-01

    Full Text Available Nonhomologous end-joining (NHEJ is the primary DNA repair pathway thought to underlie chromosomal translocations and other genomic rearrangements in somatic cells. The canonical NHEJ pathway, including DNA ligase IV (Lig4, suppresses genomic instability and chromosomal translocations, leading to the notion that a poorly defined, alternative NHEJ (alt-NHEJ pathway generates these rearrangements. Here, we investigate the DNA ligase requirement of chromosomal translocation formation in mouse cells. Mammals have two other DNA ligases, Lig1 and Lig3, in addition to Lig4. As deletion of Lig3 results in cellular lethality due to its requirement in mitochondria, we used recently developed cell lines deficient in nuclear Lig3 but rescued for mitochondrial DNA ligase activity. Further, zinc finger endonucleases were used to generate DNA breaks at endogenous loci to induce translocations. Unlike with Lig4 deficiency, which causes an increase in translocation frequency, translocations are reduced in frequency in the absence of Lig3. Residual translocations in Lig3-deficient cells do not show a bias toward use of pre-existing microhomology at the breakpoint junctions, unlike either wild-type or Lig4-deficient cells, consistent with the notion that alt-NHEJ is impaired with Lig3 loss. By contrast, Lig1 depletion in otherwise wild-type cells does not reduce translocations or affect microhomology use. However, translocations are further reduced in Lig3-deficient cells upon Lig1 knockdown, suggesting the existence of two alt-NHEJ pathways, one that is biased toward microhomology use and requires Lig3 and a back-up pathway which does not depend on microhomology and utilizes Lig1.

  10. Fibronectin promotes proplatelet formation in the human megakaryocytic cell line UT-7/TPO.

    Science.gov (United States)

    Kawaguchi, Tatsuya; Hatano, Ryo; Yamaguchi, Kyoji; Nawa, Katsuhiko; Hashimoto, Ryuji; Yokota, Hiroshi

    2012-01-01

    We investigated PPF (proplatelet formation) in the human megakaryocytic cell line UT-7/TPO in vitro and signal transduction pathways responsible for PPF. The megakaryocytic cell lines are useful for studying megakaryocyte biology, although PPF is induced only in the presence of phorbol ester. TPO (thrombopoietin) stimulates megakaryocyte proliferation and differentiation; however, no PPF occurred in the megakaryocytic cell lines, even after the addition of TPO. Therefore, factors other than TPO may play an important role in the process of PPF. As PPF occurs in the bone marrow in vivo, we noted extracellular matrix proteins and found that soluble FN (fibronectin) induced potent PPF in UT-7/TPO without phorbol ester. A Western blot analysis showed that the expression of integrins was not increased by FN treatment. Anti-β1 antibody and the RGD (arginine-glycine-aspartate) peptide inhibited FN-induced PPF. This result indicates that the signal originated from integrin β1, which is essential to inducing PPF in UT-7/TPO. Results of the experiments using several inhibitors suggest that activation of the MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase]-ERK and PI3K (phosphoinositide 3-kinase) pathways are necessary for PPF. The phosphorylation of ERK gradually increased for 2 h after the addition of soluble FN, which suggests that activation of ERK is essential for the initial induction of FN-induced PPF in UT-7/TPO. UT-7/TPO is a useful cell line that enables us to study the signals of PPF without effects of chemical compounds.

  11. Soluble THSD7A is an N-glycoprotein that promotes endothelial cell migration and tube formation in angiogenesis.

    Directory of Open Access Journals (Sweden)

    Meng-Wei Kuo

    Full Text Available BACKGROUND: Thrombospondin type I domain containing 7A (THSD7A is a novel neural protein that is known to affect endothelial migration and vascular patterning during development. To further understand the role of THSD7A in angiogenesis, we investigated the post-translational modification scheme of THS7DA and to reveal the underlying mechanisms by which this protein regulates blood vessel growth. METHODOLOGY/PRINCIPAL FINDINGS: Full-length THSD7A was overexpressed in human embryonic kidney 293T (HEK293T cells and was found to be membrane associated and N-glycosylated. The soluble form of THSD7A, which is released into the cultured medium, was harvested for further angiogenic assays. We found that soluble THSD7A promotes human umbilical vein endothelial cell (HUVEC migration and tube formation. HUVEC sprouts and zebrafish subintestinal vessel (SIV angiogenic assays further revealed that soluble THSD7A increases the number of branching points of new vessels. Interestingly, we found that soluble THSD7A increased the formation of filopodia in HUVEC. The distribution patterns of vinculin and phosphorylated focal adhesion kinase (FAK were also affected, which implies a role for THSD7A in focal adhesion assembly. Moreover, soluble THSD7A increased FAK phosphorylation in HUVEC, suggesting that THSD7A is involved in regulating cytoskeleton reorganization. CONCLUSIONS/SIGNIFICANCE: Taken together, our results indicate that THSD7A is a membrane-associated N-glycoprotein with a soluble form. Soluble THSD7A promotes endothelial cell migration during angiogenesis via a FAK-dependent mechanism and thus may be a novel neuroangiogenic factor.

  12. Gastric LTi cells promote lymphoid follicle formation but are limited by IRAK-M and do not alter microbial growth.

    Science.gov (United States)

    Shiu, J; Piazuelo, M B; Ding, H; Czinn, S J; Drakes, M L; Banerjee, A; Basappa, N; Kobayashi, K S; Fricke, W F; Blanchard, T G

    2015-09-01

    Lymphoid tissue inducer (LTi) cells are activated by accessory cell IL-23, and promote lymphoid tissue genesis and antibacterial peptide production by the mucosal epithelium. We investigated the role of LTi cells in the gastric mucosa in the context of microbial infection. Mice deficient in IRAK-M, a negative regulator of TLR signaling, were investigated for increased LTi cell activity, and antibody mediated LTi cell depletion was used to analyze LTi cell dependent antimicrobial activity. H. pylori infected IRAK-M deficient mice developed increased gastric IL-17 and lymphoid follicles compared to wild type mice. LTi cells were present in naive and infected mice, with increased numbers in IRAK-M deficient mice by two weeks. Helicobacter and Candida infection of LTi cell depleted rag1(-/-) mice demonstrated LTi-dependent increases in calprotectin but not RegIII proteins. However, pathogen and commensal microbiota populations remained unchanged in the presence or absence of LTi cell function. These data demonstrate LTi cells are present in the stomach and promote lymphoid follicle formation in response to infection, but are limited by IRAK-M expression. Additionally, LTi cell mediated antimicrobial peptide production at the gastric epithelium is less efficacious at protecting against microbial pathogens than has been reported for other tissues.

  13. Tumor promoters cause a rapid and reversible inhibition of the formation and maintenance of electrical cell coupling in culture.

    Science.gov (United States)

    Enomoto, T; Sasaki, Y; Shiba, Y; Kanno, Y; Yamasaki, H

    1981-01-01

    The effect of tumor promoters on electrical coupling between human FL cells was investigated with a microelectrode technique. When a low concentration (100 ng/ml) of 12-O-tetradecanoylphorbol 13-acetate (TPA) was added to culture medium, only 6% of the cells showed electrical coupling after 5 hr, whereas in control medium more than 90% of the cells were coupled. In the presence of TPA, cell coupling remained suppressed for at least another 19 hr. When TPA was washed out from the culture medium, the cells commenced electrical coupling: 90% of the cells were coupled within 4 hr of the removal of TPA, a rate very similar to that of nontreated control cells. Therefore, TPA-mediated inhibition of cell coupling is reversible. When TPA was added to a culture in which more than 90% of the cells had already established electrical coupling, the percentage of coupled cells decreased to 6% within 8 hr, indicating that TPA can also diminish already established cell coupling. Inhibition of cell coupling also was achieved with other mouse skin tumor promoters--phorbol 12,13-didecanoate, ingenol dibenzoate, and mezerein--whereas nonpromoting derivatives--phorbol and 4 alpha-phorbol 12,13-didecanoate-showed no effect. None of these compounds changed the membrane potential, membrane resistance, or growth rate of FL cells. Thus, it appears that TPA and structurally-related tumor promoters specifically disturb the formation or function, or both, of cell-cell junctions, without significantly affecting the general properties of the surface membrane or the growth of FL cells. Images PMID:6946500

  14. Features of Formation of Ohmic Contacts and Gate on Epitaxial Heterostructure of AlGaN / GaN High Electron Mobility Transistor

    Directory of Open Access Journals (Sweden)

    I.A. Rogachev

    2016-06-01

    Full Text Available Reported about study of processes of formation of Ti / Al / Ni / Au ohmic contacts to heterostructures AlGaN / GaN and gate Ni / Au. Investigated of process recess the semiconductor layer for minimum resistance of ohmic contact – 0.4 Ohm·mm. Studied influence of encapsulation ohmic contacts on their surface morphology.

  15. aPKC phosphorylates JAM-A at Ser285 to promote cell contact maturation and tight junction formation.

    Science.gov (United States)

    Iden, Sandra; Misselwitz, Steve; Peddibhotla, Swetha S D; Tuncay, Hüseyin; Rehder, Daniela; Gerke, Volker; Robenek, Horst; Suzuki, Atsushi; Ebnet, Klaus

    2012-03-05

    The PAR-3-atypical protein kinase C (aPKC)-PAR-6 complex has been implicated in the development of apicobasal polarity and the formation of tight junctions (TJs) in vertebrate epithelial cells. It is recruited by junctional adhesion molecule A (JAM-A) to primordial junctions where aPKC is activated by Rho family small guanosine triphosphatases. In this paper, we show that aPKC can interact directly with JAM-A in a PAR-3-independent manner. Upon recruitment to primordial junctions, aPKC phosphorylates JAM-A at S285 to promote the maturation of immature cell-cell contacts. In fully polarized cells, S285-phosphorylated JAM-A is localized exclusively at the TJs, and S285 phosphorylation of JAM-A is required for the development of a functional epithelial barrier. Protein phosphatase 2A dephosphorylates JAM-A at S285, suggesting that it antagonizes the activity of aPKC. Expression of nonphosphorylatable JAM-A/S285A interferes with single lumen specification during cyst development in three-dimensional culture. Our data suggest that aPKC phosphorylates JAM-A at S285 to regulate cell-cell contact maturation, TJ formation, and single lumen specification.

  16. Pulsed electromagnetic fields partially preserve bone mass, microarchitecture, and strength by promoting bone formation in hindlimb-suspended rats.

    Science.gov (United States)

    Jing, Da; Cai, Jing; Wu, Yan; Shen, Guanghao; Li, Feijiang; Xu, Qiaoling; Xie, Kangning; Tang, Chi; Liu, Juan; Guo, Wei; Wu, Xiaoming; Jiang, Maogang; Luo, Erping

    2014-10-01

    A large body of evidence indicates that pulsed electromagnetic fields (PEMF), as a safe and noninvasive method, could promote in vivo and in vitro osteogenesis. Thus far, the effects and underlying mechanisms of PEMF on disuse osteopenia and/or osteoporosis remain poorly understood. Herein, the efficiency of PEMF on osteoporotic bone microarchitecture, bone strength, and bone metabolism, together with its associated signaling pathway mechanism, was systematically investigated in hindlimb-unloaded (HU) rats. Thirty young mature (3-month-old), male Sprague-Dawley rats were equally assigned to control, HU, and HU + PEMF groups. The HU + PEMF group was subjected to daily 2-hour PEMF exposure at 15 Hz, 2.4 mT. After 4 weeks, micro-computed tomography (µCT) results showed that PEMF ameliorated the deterioration of trabecular and cortical bone microarchitecture. Three-point bending test showed that PEMF mitigated HU-induced reduction in femoral mechanical properties, including maximum load, stiffness, and elastic modulus. Moreover, PEMF increased serum bone formation markers, including osteocalcin (OC) and N-terminal propeptide of type 1 procollagen (P1NP); nevertheless, PEMF exerted minor inhibitory effects on bone resorption markers, including C-terminal crosslinked telopeptides of type I collagen (CTX-I) and tartrate-resistant acid phosphatase 5b (TRAcP5b). Bone histomorphometric analysis demonstrated that PEMF increased mineral apposition rate, bone formation rate, and osteoblast numbers in cancellous bone, but PEMF caused no obvious changes on osteoclast numbers. Real-time PCR showed that PEMF promoted tibial gene expressions of Wnt1, LRP5, β-catenin, OPG, and OC, but did not alter RANKL, RANK, or Sost mRNA levels. Moreover, the inhibitory effects of PEMF on disuse-induced osteopenia were further confirmed in 8-month-old mature adult HU rats. Together, these results demonstrate that PEMF alleviated disuse-induced bone loss by promoting skeletal anabolic activities

  17. Studies of the structure and function of Mms6, a bacterial protein that promotes the formation of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijun [Iowa State Univ., Ames, IA (United States)

    2011-01-01

    Here we report structural and functional studies of Mms6, a biomineralization protein that can promote the formation in vitro of magnetic nanoparticles with sizes and morphologies similar to the magnetites synthesized by magnetotactic bacteria. We found the binding pattern of Mms6 to ferric ion to be two-phase and multivalent. We quantatively determined that Mms6 binds one Fe3+ with a very high affinity (Kd = 1016 M). The second phase of iron binding is multivalent and cooperative with respect to iron with a Kd in the μM range and a stoichiometry of about 20 ferric ion per protein molecule. We found that Mms6 exists in large particles of two sizes, one consisting of 20-40 monomeric units and the other of 200 units. From proteolytic digestion, ultracentrifugation and liposome fusion studies, we found that Mms6 forms a large micellar quaternary structure with the N-terminal domain self-assembling into a uniformly sized micelle and the C-terminal domain on the surface. The two-phase iron-binding pattern may be relevant to iron crystal formation. We propose that the first high affinity phase may stabilize a new conformation of the C-terminal domain that allows interaction with other C-terminal domains leading to a structural change in the multimeric protein complex that enables the second low affinity iron binding phase to organize iron and initiate crystal formation. We also observed a dimeric apparent molecular mass of the Mms6 C-terminal peptide (C21Mms6). We speculate that the C-terminal domain may form higher order quaternary arrangements on the surface of the micelle or when anchored to a membrane by the N-terminal domain. The change in fluorescence quenching in the N-terminal domain with iron binding suggests a structural integrity between the C- and N-terminal domains. The slow change in trp fluorescence as a function of time after adding iron suggests a very slow conformational change in the protein that involves

  18. Ni/CeO{sub 2}-Al{sub 2}O{sub 3} catalysts promoted with noble metals for the hydrogen production by ethanol vapor reforming; Catalisadores de Ni/CeO{sub 2}-Al{sub 2}O{sub 3} promovidos com metais nobres para a producao de hidrogenio por reforma a vapor de etanol

    Energy Technology Data Exchange (ETDEWEB)

    Profeti, Luciene P.R.; Ticianelli, Edson Antonio; Assaf, Elisabete Moreira [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: eassaf@iqsc.usp.br

    2008-07-01

    The catalytic activity of Ni/CeO{sub 2}-Al{sub 2}O{sub 3} catalysts modified with noble metals (Ru, Ir, Pt and Pd) was investigated in the steam reforming of ethanol. The catalysts were characterized by energy dispersive spectroscopy, X-ray diffraction, UV-Vis diffuse reflectance spectroscopy and H{sub 2} temperature-programmed reduction-X-ray absorption fine structure (XANES). The results showed that the formation of inactive nickel aluminate was avoided due to the presence of a CeO{sub 2} dispersed on the alumina. The promoting effect of noble metals included a decrease of the reduction temperatures of NiO species interacting with the support due to the hydrogen spillover effect, leading to an increase of the reducibilities of the promoted catalysts The better catalytic performance for the ethanol steam reforming was obtained for the NiPd/CeAl catalyst, which presented an effluent gaseous mixture with the highest H{sub 2} yield. (author)

  19. The chip-flow behaviors and formation mechanisms in the orthogonal cutting process of Ti6Al4V alloy

    Science.gov (United States)

    Ma, Wei; Chen, Xiangyu; Shuang, Fei

    2017-01-01

    This work involves experimental and analytical investigations of chip flow stability in metal cutting process. First, in cutting experiments of Ti6Al4V alloy, the transformation of chip morphology from continuous to serrated and later to discontinuous was observed as the cutting speed increased. Scanning electron microscopic (SEM) observation of the shear fracture surface demonstrated shear-localized instability and intergranular failure behaviors. Then we used the improved orthogonal cutting model (OCM) to analyze the plastic flow process of work materials in a plane strain state. A corresponding governing equation system was set up, the dimensionless governing parameters were determined by dimensional analysis, and an instability criterion was established by linear perturbation analysis. Analytical results showed that the plastic instability of chip flow could take place in a continuous chip, which is different from the shear-localized instability in a serrated chip. Finally, in terms of the balance conditions between the kinetic energy and the surface energy, the sawtooth growth behavior in serrated chips and the formation mechanism of discontinuous chips were studied.

  20. Synthesis of novel analogues of the delta opioid ligand SNC-80 using AlCl3-promoted aminolysis.

    Science.gov (United States)

    Barn, D R; Bom, A; Cottney, J; Caulfield, W L; Morphy, J R

    1999-05-03

    Two focused libraries of delta opioid ligands were synthesised using AlCl3 facilitated aminolysis. Several compounds were identified with DOR binding affinities higher or similar to SNC-80. A novel acyclic derivative of SNC-80 produced antinociception in the acetic acid abdominal constriction test, which is at least partially mediated via the delta-opioid receptor.

  1. Solcoseryl, a tissue respiration stimulating agent, significantly enhances the effect of capacitively coupled electric field on the promotion of bone formation around dental implants.

    Science.gov (United States)

    Ochi, Morio; Wang, Pao-Li; Ohura, Kiyoshi; Takashima, Shigenori; Kagami, Hiroyuki; Hirose, Yukito; Kaku, Tohru; Sakaguchi, Kunihiko

    2003-06-01

    In the present study we examined the combined effect of application of a capacitively coupled electric field (CCEF) and the tissue respiration stimulating agent, Solcoseryl, on the promotion of bone formation around dental implants histologically and mechanically. After a dental implant was inserted into each femur of Japanese white rabbits, Solcoseryl (2 ml/kg) was administered intravenously in the ear vein and a CCEF was applied for 4 h per day for 14 days. The degree of bone formation on microscopic observation, bone contact ratio, bone surface area ratio, and the level of removal torque of the implant in the Solcoseryl- and CCEF-treated group were significantly higher than the respective value in the control group, which had not been treated with Solcoseryl nor CCEF. Thus, the combination of CCEF stimulation and Solcoseryl effectively promoted the formation of new bone. It is suggested that the clinical use of a combination of CCEF stimulation and Solcoseryl for dental implants promotes osseointegration.

  2. IN-SITU FORMATION AND DENSIFICATION OF MgAl2O4-SmAlO3 CERAMICS BY A SINGLE-STAGE REACTION SINTERING PROCESS

    Directory of Open Access Journals (Sweden)

    Beiyue Ma

    2015-06-01

    Full Text Available Stoichiometric magnesium aluminate spinel (MgAl2O4, MA-samarium aluminate (SmAlO3, SA ceramics have been prepared at 1580oC for 4 h from calcined magnesia (MgO, commercial alumina (Al2O3 and samarium oxide (Sm2O3 by a single-stage in-situ reaction sintering (SIRS method. The phase compositions, microstructures, shrinkage ratio, bulk density and cold compressive strength of the MA-SA ceramics have been investigated. The ceramics with 2.5 - 7.5 wt. % Sm2O3 are composed of MA and SA phases. The microstructures of the ceramics are dense. MA particles exist as angular shape, and their grain size varies between 2 and 10 μm but the average grain size is about 5 μm. SmAlO3 particles form due to the reaction of Sm2O3 and Al2O3, and they distribute in the intergranular space of MA grains. The diameter shrinkage ratio, volume shrinkage ratio, bulk density and cold compressive strength of MA-SA ceramics are greatly improved due to the addition of Sm2O3

  3. Formats

    Directory of Open Access Journals (Sweden)

    Gehmann, Ulrich

    2012-03-01

    Full Text Available In the following, a new conceptual framework for investigating nowadays’ “technical” phenomena shall be introduced, that of formats. The thesis is that processes of formatting account for our recent conditions of life, and will do so in the very next future. It are processes whose foundations have been laid in modernity and which will further unfold for the time being. These processes are embedded in the format of the value chain, a circumstance making them resilient to change. In addition, they are resilient in themselves since forming interconnected systems of reciprocal causal circuits.Which leads to an overall situation that our entire “Lebenswelt” became formatted to an extent we don’t fully realize, even influencing our very percep-tion of it.

  4. Methane Decomposition over Ni/α-Al2O3 Promoted by La2O3 and CeO2

    Institute of Scientific and Technical Information of China (English)

    Pengbo Jiang; Yongchen Shang; Tiexin Cheng; Yingli Bi; Keying Shi; Shuquan Wei; Guolin Xu; Kaiji Zhen

    2003-01-01

    The decomposition of methane on Ni/α-Al2O3 modified by La2O3 and CeO2 with different contents has been investigated and the ralationship between methane decomposition and removal of carbon by CO2 over these catalyst has also been studied by pulse-chromatography. The catalysts were characterized by TPR and XRD. It was shown that Ni/α-Al2O3 could be promoted by adding La2O3, and the carbon species produced over this catalyst was activated and eliminated by CO2. But CeO2 would suppress the decomposition of methane over Ni crystallite. Both La2O3 and CeO2 can inhibit aggregation of the Ni particles. Decomposition of methane over the Ni-based catalysts is structure sensitive to a certain extent.

  5. Al-Cd Alloy Formation by Aluminum Underpotential Deposition from AlCl3+NaCl Melts on Cadmium Substrate

    Science.gov (United States)

    Jovićević, Niko; Cvetković, Vesna S.; Kamberović, Željko J.; Jovićević, Jovan N.

    2013-02-01

    Aluminum was incorporated into a polycrystalline cadmium electrode surface by underpotential deposition from equimolar AlCl3+ NaCl melt at 473 K, 523 K, and 573 K (200 °C, 250 °C, and 300 °C). The process was studied by linear sweep voltammetry and potentiostatic deposition/galvanostatic striping. The deposits were characterized X-ray diffraction (XRD), Auger electron spectroscopy (AES), and electron probe microanalyzer (EPMA). The electrochemical measurements showed evidence of Cd-Al alloys being formed but they could not be identified. The growth kinetics of the Cd-Al layers of various proportion and depths that depended on temperature and deposition time were described.

  6. Combined XRD and XANES studies of a Re-promoted Co/γ-Al2O3 catalyst at Fischer–Tropsch synthesis conditions

    DEFF Research Database (Denmark)

    Rønning, Magnus; Tsakoumis, Nikolaos E.; Voronov, Alexey

    2010-01-01

    products (FT synthesis at 483K, 18bar and low GHSV). The data analysis shows no significant changes in the cobalt crystallites during the first hours of Fischer–Tropsch synthesis. Running the reaction at higher temperatures and predominantly methanation conditions led to significant sintering of the cobalt......A cobalt based Fischer–Tropsch catalyst was studied during the initial stages of the reaction at industrially relevant conditions. The catalyst consists of 20wt% cobalt supported on γ-Al2O3 and promoted by 1wt% of rhenium. X-ray diffraction (XRD) in combination with X-ray absorption near edge...

  7. 表面态对AlGaN/GaN异质结构2DEG影响的模拟分析%Influence of surface state on 2DEG formation at AlGaN/GaN heterostructure

    Institute of Scientific and Technical Information of China (English)

    杨帆; 林哲雄; 张炜; 张金城; 王硕; 贺致远; 倪毅强; 刘扬

    2014-01-01

    The influence of surface state on two-dimensional electronic gas (2DEG)formation at AlGaN/GaN heterostructure is simulated.Specifically,the effects of AlGaN thickness,surface state energy level and surface state density changing are ana-lyzed.It is demonstrated that the electrons of 2DEG are primarily originated from surface state ionization.Simultaneously,Al-GaN thickness,surface state energy level and surface state density would be changed with the changes of AlGaN band structure and 2DEG density.%利用模拟软件研究施主表面态特性与AlGaN/GaN异质结构中二维电子气(2 dimensional electron gas,2DEG)形成之间的关系,分析施主表面态电离过程以及表面态能级位置、表面态密度的影响。结果表明:施主表面态为2DEG的电子来源;Al-GaN能带分布及2DEG密度随AlGaN厚度、施主表面态能级位置、施主表面态密度的改变而改变。

  8. 助剂对Co/Al2O3催化剂浆态床费托合成反应性能影响%Effect of promoters on the performance of Co/Al2O3 catalysts for Fischer-Tropsch synthesis in slurry reactors

    Institute of Scientific and Technical Information of China (English)

    孙燕; 孙启文; 蒋凡凯; 张宗森; 刘继森

    2012-01-01

    The effect of ZrO2, Ru and/or Pt promoters on the structure and performance of Co/Al2O3 catalysts for Fischer-Tropsch synthesis in a slurry reactor was investigated. The results indicated that ZrO2 modification may prevent or reduce the formation of CoAl2O4 phase on the catalysts and improve the reduction of cobalt species, which is beneficial to the increase of the catalytic activity, the decrease of methane selectivity, as well as the improvement of C5+ selectivity. Small amounts of ruthenium and platinum as promoter are able to lower the reduction temperatures of cobalt species (Co3O4→CoO and CoO→Co°) and to get a high reduction extent; as a result, the catalysts promoted with noble metals exhibit much higher activity in CO hydrogenation. Moreover, the impregnation sequence of various components also has an important influence on the performance of resultant catalysts in Fischer-Tropsch synthesis. Impregnation of γ-Al2O3 with Zr at first, the formation of irreducible cobalt aluminate can be prevented; co-impregnation of γ-A12O3 with Co and Ru can enhance the interaction between cobalt and ruthenium, which benefits to the reduction of cobalt oxides; sequential impregnation of γ-Al2O3 with Co and Pt is beneficial to the dispersion of cobalt species. As a result, the sequentially impregnated catalyst Co-Pt-ZrO2/Al2O3 performs excellently in the Fischer-Tropsch synthesis.%考察了ZrO2、Ru或Pt助剂对Co/Al2O3催化剂结构及浆态床费托合成反应性能的影响.实验结果表明,添加ZrO2助剂可阻止或降低难还原铝酸钴的形成、促进催化剂的还原、提高Co/Al2O3催化剂对费托合成反应的催化活性、降低甲烷选择性并提高C5+烃选择性.H2-TPR表征结果表明,少量Ru或Pt助剂均能降低Co-ZrO2/Al2O3催化剂中钴物种还原温度(Co3O4→CoO和CoO→Co0),提高催化剂的还原度,催化剂呈现出良好的CO加氢反应活性.此外,催化剂组分间浸渍次序对费托合成反应性

  9. Effect of Y2O3 and TiC Reinforcement Particles on Intermetallic Formation and Hardness of Al6061 Composites via Mechanical Alloying and Sintering

    Science.gov (United States)

    Chen, Chun-Liang; Lin, Chen-Han

    2015-08-01

    Al6061-based composites reinforced with 2 wt pctY2O3 and 2 wt pctTiC particles produced by mechanical alloying were investigated. The reinforced particles play important roles in the microstructural development and in determining the properties of the alloys. High-energy ball milling can facilitate a solid-state reaction between reinforced particles and the Al matrix, and the reaction kinetics of atomic diffusion can be accelerated enormously by subsequent sintering processing. As a result, complex intermetallic compounds and oxide particles can be formed in the alloy. In this study, the effect of reinforcement on phase formation and mechanical properties of Al6061-based composites has been examined. The results suggest that nano-Y2O3 particles can act as nucleation sites to facilitate formation of Al-Si-Y-O-based oxide particles. The addition of TiC particles can effectively refine the grain structure and encourage formation of iron-rich intermetallic compounds. Nanoindentation was used to understand the local variations in mechanical properties of the Al6061-based composites.

  10. Formation of abrasion-resistant coatings of the AlSiFe{sub x}Mny intermetallic compound type on the AISI 304L alloy

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Peralez, L. G.; Flores-Valdes, A.; Salinas-Rodriguez, A.; Ochoa-Palacios, R. M.; Toscano-giles, J. A.; Torres-Torres, J.

    2016-05-01

    The α-Al{sub 9}FeMnSi and α-Al{sub 9}FeMn{sub 2}Si intermetallics formed by reactive sintering of Al, Si, Mn, Fe, Cr and Ni powders have been used in AISI 304L steels to enhance microhardness. Processing variables of the reactive sintering treatment were temperature (600, 650, 700, 750 and 800 degree centigrade), pressure (5, 10 y 20 MPa) and holding time (3600, 5400 y 7200 seconds). Experimental results show that temperature is the most important variable affecting the substrate/coating formation, while pressure does not appear to have a significant effect. The results show the optimum conditions of the reactive sintering that favor the substrate/coating formation are 800 degree centigrade, 20 MPa and 7200 seconds. Under these conditions, the reaction zone between the substrate and coating is more compacted and well-adhered, with a microhardness of 1300 Vickers. The results of SEM and X-Ray diffraction confirmed the formation of β-Al{sub 9}FeMnSi and β-Al{sub 9}FeMn{sub 2}Si intermetallics in the substrate/coating interface as well as the presence of Cr and Ni, indicating diffusion of these two elements from the substrate to the interface. (Author)

  11. Lanthanum cobalt oxides as models for La-promoted Co/{gamma}-Al{sub 2}O{sub 3} catalys

    Energy Technology Data Exchange (ETDEWEB)

    Hansteen, Ole Henrik

    1998-12-31

    Cobalt supported on {gamma}-Al{sub 2}O{sub 3} have for a long time been interesting catalysts for the synthesis of hydrocarbons by hydrogenation of carbonmonoxide, the so-called Fischer-Tropsch synthesis. The reduction and catalytic properties of these catalysts are largely improved by addition of promotors like rhenium and lanthanum. This thesis attempts to provide additional knowledge to the nature of the reduction processes from metal oxides via partially reduced phases into metal and to the large degree of interaction/reaction between the catalyst components. It focuses on detailed studies of model oxides in the La-Co-O and Co-Al-O systems under reducing conditions typically used for the synthesis of the catalysts. 132 refs., 41 figs., 16 tabs.

  12. Electrochemical promotion of propane oxidation on Pt deposited on a dense β"-Al2O3 ceramic Ag+ conductor

    Science.gov (United States)

    Tsampas, Michail; Kambolis, Anastasios; Obeid, Emil; Lizarraga, Leonardo; Sapountzi, Foteini; Vernoux, Philippe

    2013-08-01

    A new kind of electrochemical catalyst based on a Pt porous catalyst film deposited on a β"-Al2O3 ceramic Ag+ conductor was developed and evaluated during propane oxidation. It was observed that upon anodic polarization, the rate of propane combustion was significantly electropromoted up to 400%. Moreover, for the first time, exponential increase of the catalytic rate was evidenced during galvanostatic transient experiment in excellent agreement with EPOC equation.

  13. Electrochemical promotion of propane oxidation on Pt deposited on a dense β"-Al2O3 ceramic Ag+ conductor

    Directory of Open Access Journals (Sweden)

    Michail eTsampas

    2013-08-01

    Full Text Available A new kind of electrochemical catalyst based on a Pt porous catalyst film deposited on a β"-Al2O3 ceramic Ag+ conductor was developed and evaluated during propane oxidation. It was observed that upon anodic polarization, the rate of propane combustion was significantly electropromoted up to 400%. Moreover, for the first time, exponential increase of the catalytic rate was evidenced during galvanostatic transient experiment in excellent agreement with EPOC equation.

  14. The immobilized NaHSO4·H2O on activated charcoal: a highly efficient promoter system for N-formylation of amines with ethyl formate

    Directory of Open Access Journals (Sweden)

    Behzad Zeynizadeh

    2016-03-01

    Full Text Available The immobilized NaHSO4·H2O on activated charcoal was used as a highly efficient promoter system for facile N-formylation of amines with ethyl formate. All reactions were carried out in refluxing ethyl formate (54 ºC under mild conditions within 10-100 min to afford the product formamides in high to excellent yields (80-94%.

  15. Shoot bending promotes flower bud formation by miRNA-mediated regulation in apple (Malus domestica Borkh.).

    Science.gov (United States)

    Xing, Libo; Zhang, Dong; Zhao, Caiping; Li, Youmei; Ma, Juanjuan; An, Na; Han, Mingyu

    2016-02-01

    Flower induction in apple (Malus domestica Borkh.) trees plays an important life cycle role, but young trees produce fewer and inferior quality flower buds. Therefore, shoot bending has become an important cultural practice, significantly promoting the capacity to develop more flower buds during the growing seasons. Additionally, microRNAs (miRNAs) play essential roles in plant growth, flower induction and stress responses. In this study, we identified miRNAs potentially involved in the regulation of bud growth, and flower induction and development, as well as in the response to shoot bending. Of the 195 miRNAs identified, 137 were novel miRNAs. The miRNA expression profiles revealed that the expression levels of 68 and 27 known miRNAs were down-regulated and up-regulated, respectively, in response to shoot bending, and that the 31 differentially expressed novel miRNAs between them formed five major clusters. Additionally, a complex regulatory network associated with auxin, cytokinin, abscisic acid (ABA) and gibberellic acid (GA) plays important roles in cell division, bud growth and flower induction, in which related miRNAs and targets mediated regulation. Among them, miR396, 160, 393, and their targets associated with AUX, miR159, 319, 164, and their targets associated with ABA and GA, and flowering-related miRNAs and genes, regulate bud growth and flower bud formation in response to shoot bending. Meanwhile, the flowering genes had significantly higher expression levels during shoot bending, suggesting that they are involved in this regulatory process. This study provides a framework for the future analysis of miRNAs associated with multiple hormones and their roles in the regulation of bud growth, and flower induction and formation in response to shoot bending in apple trees.

  16. Initial Processes of Atomic Layer Deposition of Al2O3 on InGaAs: Interface Formation Mechanisms and Impact on Metal-Insulator-Semiconductor Device Performance

    Directory of Open Access Journals (Sweden)

    Shinichi Takagi

    2012-03-01

    Full Text Available Interface-formation processes in atomic layer deposition (ALD of Al2O3 on InGaAs surfaces were investigated using on-line Auger electron spectroscopy. Al2O3 ALD was carried out by repeating a cycle of Al(CH33 (trimethylaluminum, TMA adsorption and oxidation by H2O. The first two ALD cycles increased the Al KLL signal, whereas they did not increase the O KLL signal. Al2O3 bulk-film growth started from the third cycle. These observations indicated that the Al2O3/InGaAs interface was formed by reduction of the surface oxides with TMA. In order to investigate the effect of surface-oxide reduction on metal-insulator-semiconductor (MIS properties, capacitors and field-effect transistors (FETs were fabricated by changing the TMA dosage during the interface formation stage. The frequency dispersion of the capacitance-voltage characteristics was reduced by employing a high TMA dosage. The high TMA dosage, however, induced fixed negative charges at the MIS interface and degraded channel mobility.

  17. Effect of ultrasonic treatment on formation of iron-containing intermetallic compounds in Al-Si alloys

    Directory of Open Access Journals (Sweden)

    Yu-bo Zhang

    2016-09-01

    Full Text Available Iron is generally regarded as an unavoidable impurity in Al-Si casting alloys. The acicular Al3Fe and β-Al5FeSi (or Al9Si2Fe2 are common iron-containing intermetallic compounds (IMCs in conventional structure which have a detrimental impact on the mechanical properties. In this paper, ultrasonic field (USF was applied to modify acicular iron phases in Al-12%Si-2%Fe and Al-2%Fe alloys. The results show that the USF applied to Al-Fe alloys caused the morphological transformation of both primary and eutectic Al3Fe from acicular to blocky and granular without changes in their composition. In the case of Al-Si-Fe alloys, ultrasonic treatment led to both morphological and compositional conversion of the ternary iron IMCs. When the USF was applied, the acicular β-Al9Si2Fe2 was substituted by star-like α-Al12Si2Fe3. The modification rate of both binary and ternary iron IMCs relates to the USF treatment duration. The undercooling induced by the ultrasonic vibration contributes to the nucleation of intermetallics and can explain the transformation effect.

  18. HYDROESTERIFICATION OF ACETYLENE WITH METHYL FORMATE TO METHYL ACRYLATE OVER A NiO/Al203 CATALYST: EFFECTS OF NiO LOADING AND CALCINATION TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    Huang Xinhan; Yang Xiangui; Zhang Jiaqi; Liu Zhaotie

    2001-01-01

    Hydroesterification of acetylene with methyl formate (MF) was studied over a series of nickel-supported catalysts with NiO loading varing from 0.8 wt% to 18.7 wt% and calcination temperature ranging from 623 K to 873 K. The catalyst was studied by TPR, XPS, XRD and BET. The interactions between impregnated Ni2+ and alumina during catalyst preparation produced different kinds of nickel species such as NiO crystallites and NiAl2O4-like species, and their distributions varied with NiO loading and calcination temperature, which leads to different activities of catalyst in hydroesterification of acetylene with methyl formate. Experimental results indicated that 10wt% NiO/Al2O3 calcined at 773 K is suitable for the hydroesterification of acetylene with methyl formate.

  19. Effect of CeO2 and CaO Promoters on Ignition Performance for Partial Oxidation of Methane over Ni/MgO-Al2O3 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Yejun Qiu; Jixiang Chen; Jiyan Zhang

    2007-01-01

    The effect of CeO2 and CaO promoters on the ignition performance over Ni/MgO-Al2O3 catalyst for the partial oxidation of methane (POM) to synthesis gas was investigated. It was found that the POM reaction could not be ignited over 1wt%Ni/MgO-Al2O3 catalyst without the promoters in the temperature range from 773 K to 1073 K. CeO2 and CaO promoters enhanced the ignition performance and the POM reactivity of 1wt%Ni/MgO-Al2O3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactionconditions. The modification effects of CeO2 and CaO promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species.

  20. Influence of inelastic collisions with hydrogen atoms on the formation of AlI and SiI lines in stellar spectra

    Science.gov (United States)

    Mashonkina, L. I.; Belyaev, A. K.; Shi, J.-R.

    2016-06-01

    We have performed calculations by abandoning the assumption of local thermodynamic equilibrium (within the so-called non-LTE approach) for Al I and Si I with model atmospheres corresponding to stars of spectral types F-G-Kwith differentmetal abundances. To take into account inelastic collisions with hydrogen atoms, for the first time we have applied the cross sections calculated by Belyaev et al. using model approaches within the formalism of the Born-Oppenheimer quantum theory. We show that for Al I non-LTE leads to higher ionization (overionization) than in LTE in the spectral line formation region and to a weakening of spectral lines, which is consistent with earlier non-LTE studies. However, our results, especially for the subordinate lines, differ quantitatively from the results of predecessors. Owing to their large cross sections, the ion-pair production and mutual neutralization processes Al I( nl) + HI(1 s) ↔ Al II(3 s 2) + H- provide a close coupling of highly excited Al I levels with the Al II ground state, which causes the deviations from the equilibrium level population to decrease compared to the calculations where the collisions only with electrons are taken into account. For three moderately metal-deficient dwarf stars, the aluminum abundance has been determined from seven Al I lines in different models of their formation. Under the assumption of LTE and in non-LTE calculations including the collisions only with electrons, the Al I 3961 ˚A resonance line gives a systematically lower abundance than the mean abundance from the subordinate lines, by 0.25-0.45 dex. The difference for each star is removed by taking into account the collisions with hydrogen atoms, and the rms error of the abundance derived from all seven Al I lines decreases by a factor of 1.5-3 compared to the LTE analysis. We have calculated the non- LTE corrections to the abundance for six subordinate Al I lines as a function of the effective temperature (4500 K ≤ T eff ≤ 6500 K

  1. An evaluation of a SVA retrotransposon in the FUS promoter as a transcriptional regulator and its association to ALS.

    Directory of Open Access Journals (Sweden)

    Abigail L Savage

    Full Text Available Genetic mutations of FUS have been linked to many diseases including Amyotrophic Lateral Sclerosis (ALS and Frontotemporal Lobar Degeneration. A primate specific and polymorphic retrotransposon of the SINE-VNTR-Alu (SVA family is present upstream of the FUS gene. Here we have demonstrated that this retrotransposon can act as a classical transcriptional regulatory domain in the context of a reporter gene construct both in vitro in the human SK-N-AS neuroblastoma cell line and in vivo in a chick embryo model. We have also demonstrated that the SVA is composed of multiple distinct regulatory domains, one of which is a variable number tandem repeat (VNTR. The ability of the SVA and its component parts to direct reporter gene expression supported a hypothesis that this region could direct differential FUS expression in vivo. The SVA may therefore contribute to the modulation of FUS expression exhibited in and associated with neurological disorders including ALS where FUS regulation may be an important parameter in progression of the disease. As VNTRs are often clinical associates for disease progression we determined the extent of polymorphism within the SVA. In total 2 variants of the SVA were identified based within a central VNTR. Preliminary analysis addressed the association of these SVA variants within a small sporadic ALS cohort but did not reach statistical significance, although we did not include other parameters such as SNPs within the SVA or an environmental factor in this analysis. The latter may be particularly important as the transcriptional and epigenetic properties of the SVA are likely to be directed by the environment of the cell.

  2. Phenylethanol promotes adhesion and biofilm formation of the antagonistic yeast Kloeckera apiculata for the control of blue mold on citrus.

    Science.gov (United States)

    Pu, Liu; Jingfan, Fang; Kai, Chen; Chao-an, Long; Yunjiang, Cheng

    2014-06-01

    The yeast Kloeckera apiculata strain 34-9 is an antagonist with biological control activity against postharvest diseases of citrus fruit. In a previous study it was demonstrated that K. apiculata produced the aromatic alcohol phenylethanol. In the present study, we found that K. apiculata was able to form biofilm on citrus fruit and embed in an extracellular matrix, which created a mechanical barrier interposed between the wound surface and pathogen. As a quorum-sensing molecule, phenylethanol can promote the formation of filaments by K. apiculata in potato dextrose agar medium, whereas on the citrus fruit, the antagonist remains as yeast after being treated with the same concentration of phenylethanol. It only induced K. apiculata to adhere and form biofilm. Following genome-wide computational and experimental identification of the possible genes associated with K. apiculata adhesion, we identified nine genes possibly involved in triggering yeast adhesion. Six of these genes were significantly induced after phenylethanol stress treatment. This study provides a new model system of the biology of the antagonist-pathogen interactions that occur in the antagonistic yeast K. apiculata for the control of blue mold on citrus caused by Penicillium italicum.

  3. Top3β is an RNA topoisomerase that works with Fragile X syndrome protein to promote synapse formation

    Science.gov (United States)

    Xu, Dongyi; Shen, Weiping; Guo, Rong; Xue, Yutong; Peng, Wei; Sima, Jian; Yang, Jay; Sharov, Alexei; Srikantan, Subramanya; Yang, Jiandong; Fox, David; Qian, Yong; Martindale, Jennifer L.; Piao, Yulan; Machamer, James; Joshi, Samit R.; Mohanty, Subhasis; Shaw, Albert C.; Lloyd, Thomas E.; Brown, Grant W.; Ko, Minoru S.H.; Gorospe, Myriam; Zou, Sige; Wang, Weidong

    2013-01-01

    Topoisomerases are crucial to solve DNA topological problems, but they have not been linked to RNA metabolism. Here we show that human topoisomerase 3β (Top3β) is an RNA topoisomerase that biochemically and genetically interacts with FMRP, a protein deficient in Fragile X syndrome and known to regulate translation of mRNAs important for neuronal function and autism. Notably, the FMRP-Top3β interaction is abolished by a disease-associated FMRP mutation, suggesting that Top3β may contribute to pathogenesis of mental disorders. Top3β binds multiple mRNAs encoded by genes with neuronal functions related to schizophrenia and autism. Expression of one such gene, ptk2/FAK, is reduced in neuromuscular junctions of Top3β mutant flies. Synapse formation is defective in Top3β mutant flies and mice, as observed in FMRP mutant animals. Our findings suggest that Top3β acts as an RNA topoisomerase and works with FMRP to promote expression of mRNAs critical for neurodevelopment and mental health. PMID:23912945

  4. Substrate-promoted formation of a catalytically competent binuclear center and regulation of reactivity in a glycerophosphodiesterase from Enterobacter aerogenes.

    Science.gov (United States)

    Hadler, Kieran S; Tanifum, Eric A; Yip, Sylvia Hsu-Chen; Mitić, Natasa; Guddat, Luke W; Jackson, Colin J; Gahan, Lawrence R; Nguyen, Kelly; Carr, Paul D; Ollis, David L; Hengge, Alvan C; Larrabee, James A; Schenk, Gerhard

    2008-10-29

    The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous binuclear metallohydrolase that catalyzes the hydrolysis of mono-, di-, and triester substrates, including some organophosphate pesticides and products of the degradation of nerve agents. GpdQ has attracted recent attention as a promising enzymatic bioremediator. Here, we have investigated the catalytic mechanism of this versatile enzyme using a range of techniques. An improved crystal structure (1.9 A resolution) illustrates the presence of (i) an extended hydrogen bond network in the active site, and (ii) two possible nucleophiles, i.e., water/hydroxide ligands, coordinated to one or both metal ions. While it is at present not possible to unambiguously distinguish between these two possibilities, a reaction mechanism is proposed whereby the terminally bound H2O/OH(-) acts as the nucleophile, activated via hydrogen bonding by the bridging water molecule. Furthermore, the presence of substrate promotes the formation of a catalytically competent binuclear center by significantly enhancing the binding affinity of one of the metal ions in the active site. Asn80 appears to display coordination flexibility that may modulate enzyme activity. Kinetic data suggest that the rate-limiting step occurs after hydrolysis, i.e., the release of the phosphate moiety and the concomitant dissociation of one of the metal ions and/or associated conformational changes. Thus, it is proposed that GpdQ employs an intricate regulatory mechanism for catalysis, where coordination flexibility in one of the two metal binding sites is essential for optimal activity.

  5. Laminin-521 Promotes Rat Bone Marrow Mesenchymal Stem Cell Sheet Formation on Light-Induced Cell Sheet Technology

    Directory of Open Access Journals (Sweden)

    Zhiwei Jiang

    2017-01-01

    Full Text Available Rat bone marrow mesenchymal stem cell sheets (rBMSC sheets are attractive for cell-based tissue engineering. However, methods of culturing rBMSC sheets are critically limited. In order to obtain intact rBMSC sheets, a light-induced cell sheet method was used in this study. TiO2 nanodot films were coated with (TL or without (TN laminin-521. We investigated the effects of laminin-521 on rBMSCs during cell sheet culturing. The fabricated rBMSC sheets were subsequently assessed to study cell sheet viability, reattachment ability, cell sheet thickness, collagen type I deposition, and multilineage potential. The results showed that laminin-521 could promote the formation of rBMSC sheets with good viability under hyperconfluent conditions. Cell sheet thickness increased from an initial 26.7 ± 1.5 μm (day 5 up to 47.7 ± 3.0 μm (day 10. Moreover, rBMSC sheets maintained their potential of osteogenic, adipogenic, and chondrogenic differentiation. This study provides a new strategy to obtain rBMSC sheets using light-induced cell sheet technology.

  6. G4-DNA formation in the HRAS promoter and rational design of decoy oligonucleotides for cancer therapy.

    Directory of Open Access Journals (Sweden)

    Alexandro Membrino

    Full Text Available HRAS is a proto-oncogene involved in the tumorigenesis of urinary bladder cancer. In the HRAS promoter we identified two G-rich elements, hras-1 and hras-2, that fold, respectively, into an antiparallel and a parallel quadruplex (qhras-1, qhras-2. When we introduced in sequence hras-1 or hras-2 two point mutations that block quadruplex formation, transcription increased 5-fold, but when we stabilized the G-quadruplexes by guanidinium phthalocyanines, transcription decreased to 20% of control. By ChIP we found that sequence hras-1 is bound only by MAZ, while hras-2 is bound by MAZ and Sp1: two transcription factors recognizing guanine boxes. We also discovered by EMSA that recombinant MAZ-GST binds to both HRAS quadruplexes, while Sp1-GST only binds to qhras-1. The over-expression of MAZ and Sp1 synergistically activates HRAS transcription, while silencing each gene by RNAi results in a strong down-regulation of transcription. All these data indicate that the HRAS G-quadruplexes behave as transcription repressors. Finally, we designed decoy oligonucleotides mimicking the HRAS quadruplexes, bearing (R-1-O-[4-(1-Pyrenylethynyl phenylmethyl] glycerol and LNA modifications to increase their stability and nuclease resistance (G4-decoys. The G4-decoys repressed HRAS transcription and caused a strong antiproliferative effect, mediated by apoptosis, in T24 bladder cancer cells where HRAS is mutated.

  7. STUDY OF MnOx-PROMOTED Cu/γ-Al203 CATALYSTS FOR HYDROGENATION OF CARBON MONOXIDE

    Institute of Scientific and Technical Information of China (English)

    Qi Gongxin; Fei Jinhua; Hou Zhaoyin; Zheng Xiaoming

    2001-01-01

    γ-Alumina-supported copper-manganese oxide was prepared by impregnation and used for carbon monoxide hydrogenation. The Cu-MnOx/γ-Al2O3 catalysts exhibit high catalytic activity in CO hydrogenation, showing markedly enhanced catalytic activities due to the synergistic interaction between the copper and manganese oxide. The results of XRD indicated that the addition of manganese enhances the dispersion of CuO, retards the reduction of CuO and enhances the ability of H2-adsorption, which contribute to the activity of DME synthesis from syngas.

  8. Effect of NiAl2O4 Formation on Ni/Al2O3 Stability during Dry Reforming of Methane

    KAUST Repository

    Zhou, Lu

    2015-07-16

    A series of alumina-supported Ni catalysts were prepared to examine their activity and carbon deposition during dry reforming of methane (DRM). With an increase in the final calcination temperature to T=900 °C to form exclusively NiAl2O4, a catalyst with strong metal–support interactions was obtained. During a long-term DRM reaction (of about t=100 h) at T=700 °C and with CH4/CO2=1:1, reduced Ni (from NiAl2O4) showed a high resistance to sintering and coking. The DRM kinetics behaviors of the catalysts calcined at different temperatures were also investigated. Carbon growth models were proposed to rationalize the different carbon morphologies observed on the catalysts.

  9. Mouse B- and T-cell colony formation in vitro. I. Separation of colony-promoting and -inhibiting activities in concanavalin A rat spleen conditioned medium

    DEFF Research Database (Denmark)

    Claësson, M H; Nissen, Mogens Holst; Röpke, C

    1984-01-01

    Rat spleen cell cultures exposed for 24 h to concanavalin A (Con A-CM) contain, in addition to interleukin 2 (IL-2), factors that promote colony formation in vitro by mouse T cells (TCPA) and B cells (BCPA). TCPA and BCPA are separable on a Sephadex G-75 column. TCPA has a molecular weight of 15...

  10. Effect of carbon on formation of mixed solid solutions during mechanochemical synthesis of Ni-Al-Mo-C mixtures and ordering of solutions during heating

    Science.gov (United States)

    Portnoi, V. K.; Leonov, A. V.; Streletskii, A. N.; Logacheva, A. I.

    2014-03-01

    Solid solutions Ni(Al, Mo, C) are formed via milling the Ni2.8Al1Mo0.2 and Ni3Al0.8Mo0.2 and graphite-containing Ni2.8Al1Mo0.2C(0.25, 0.5) and Ni3Al0.8Mo0.2C(0.25, 0.5) mixtures. In this case, some amount of Mo remains beyond the solid solution. Graphite added to a starting mixture decreases the Mo solubility and favors the amorphization of solid solutions. The complete amorphization was found for the mixture with the 5 at % C and 5 at % Mo, which was added instead of Ni. The heating of mechanically synthesized (MS) powder alloys leads to the ordering of carbon-free and carbon-containing solid solutions with the formation of the L12 and E21 structure, respectively. In the course of the ordering of the Ni(Al, Mo, C) solid solutions, Mo and carbon precipitate in the form of the molybdenum carbide (Mo2C) second phase. The hardness of the MS three-phase Ni-Al-Mo-C solid solutions subjected to hot isostatic pressing is determined by the mass fraction of the formed Mo2C carbide. It is shown that the carbon content in the multicomponent antiperovskite can be estimated by analyzing the ratio of integral intensities of superlattice reflections I (100)/ I (110).

  11. Recrystallization and formation of spheroidal gold particles in amorphous-like AlN-TiB2-TiSi2 coatings after annealing and subsequent implantation

    Science.gov (United States)

    Pogrebnjak, A. D.; Dem'yanenko, A. A.; Beresnev, V. M.; Sobol', O. V.; Ivasishin, O. M.; Oyoshi, K.; Takeda, Y.; Amekura, H.; Kupchishin, A. I.

    2016-07-01

    The recrystallization of the structure of an X-ray amorphous AlN-TiB2-TiSi2 coating containing short-range order regions with characteristic sizes of 0.8-1.0 nm has been performed using a negative gold ion (Au-) beam and high-temperature annealing. Direct measurements using methods of high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectral (EDXS) microanalysis have demonstrated that thermal annealing at a temperature of 1300°C in air results in the formation of nanoscale (10-15 nm) phases AlN, AlB2, Al3O3, and TiO2, whereas the ion implantation of negative ions Au- leads to a fragmentation (decrease in the size) of nanograins to 2-5 nm with the formation of spheroidal gold nanocrystallites a few nanometers in size, as well as to the formation of an amorphous oxide film in the depth (near-surface layer) of the coating due to ballistic ion mixing and collision cascades.

  12. The effect of polar end of long-chain fluorocarbon oligomers in promoting the superamphiphobic property over multi-scale rough Al alloy surfaces

    Science.gov (United States)

    Saifaldeen, Zubayda S.; Khedir, Khedir R.; Camci, Merve T.; Ucar, Ahmet; Suzer, Sefik; Karabacak, Tansel

    2016-08-01

    Rough structures with re-entrant property and their subsequent surface energy reduction with long-chain fluorocarbon oligomers are both critical in developing superamphiphobic (SAP, i.e. both super hydrophobic and superoleophobic) surfaces. However, morphology of the low-surface energy layer on a rough re-entrant substrate can strongly depend on the fluorocarbon oligomers used. In this study, the effect of polar end of different kinds of long-chain fluorocarbon oligomers in promoting a self-assembled monolayer with close packed molecules and robust adhesion on multi-scale rough Al alloy surfaces was investigated. Hierarchical Al alloy surfaces with microgrooves and nanograss structures were developed by a simple combination of one-directional mechanical sanding and post treatment in boiling de-ionized water (DIW). Three types of long-chain fluorocarbon oligomers of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDTS), 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (PFDCS), and perfluorooctanoic acid (PFOA) were chemically vaporized onto these rough Al alloy surfaces. The PFDCS exhibited the lowest surface free energy of less than 10 mN/m. The contact angle and sliding angle measurements for water, ethylene glycol, and peanut oil verified the SAP property of hierarchical rough Al alloy surfaces treated with alkylsilane oligomers (PFDTS, PFDCS). However, the hierarchical surfaces treated with fluorocarbon oligomer with polar acidic tail (PFOA) showed highly amphiphobic properties but could not reach the threshold for SAP. Chemical stability of the hierarchical Al alloy surfaces treated with the fluorocarbon oligomers was tested under the harsh conditions of ultra-sonication in acetone and annealing at high temperature after different treatment times. Contact angle measurements revealed the robustness of the alkylsilane oligomers and deterioration of the PFOA coating particularly for low surface tension liquids. The robust adhesion and close-packing of the alkylsilane

  13. Tungsten Promoted Ni/Al2O3 Catalysts for Carbon Dioxide Reforming of Methane to Synthesis Gas

    Institute of Scientific and Technical Information of China (English)

    XIAO Tian-cun; Thomas Suhartanto; Andrew P. E. York; Malcolm L. H. Green

    2004-01-01

    A series of tungsten promoted alumina supported nickel catalysts has been prepared for the carbon dioxide reforming of methane to synthesis gas. The catalysts have been characterized by means of XRD, TEM,and Laser Raman spectroscopy. It is shown that the addition of tungsten to the nickel catalyst can stabilize the catalyst and increase the resistance to carbon deposition. Adding a suitable amount of tungsten can also increase the catalyst activity to be close to that of supported noble metal catalysts. The carburisation of the tungsten modified nickel catalyst decreases the catalyst activity at lower reaction temperatures(<1123K),but has no effect on the catalyst performance at higher reaction temperatures. The alumina supported nickel catalyst modified by 0. 67 % (mass fraction)WOs has the equivalent equilibrium constant of the dry reforming reaction to that of alumina supported 5% (mass fraction) Ru at 873 K, and also has a lower activation energy for dry reforming than the latter.

  14. The Active Component of Aspirin, Salicylic Acid, Promotes Staphylococcus aureus Biofilm Formation in a PIA-dependent Manner.

    Science.gov (United States)

    Dotto, Cristian; Lombarte Serrat, Andrea; Cattelan, Natalia; Barbagelata, María S; Yantorno, Osvaldo M; Sordelli, Daniel O; Ehling-Schulz, Monika; Grunert, Tom; Buzzola, Fernanda R

    2017-01-01

    Aspirin has provided clear benefits to human health. But salicylic acid (SAL) -the main aspirin biometabolite- exerts several effects on eukaryote and prokaryote cells. SAL can affect, for instance, the expression of Staphylococcus aureus virulence factors. SAL can also form complexes with iron cations and it has been shown that different iron chelating molecules diminished the formation of S. aureus biofilm. The aim of this study was to elucidate whether the iron content limitation caused by SAL can modify the S. aureus metabolism and/or metabolic regulators thus changing the expression of the main polysaccharides involved in biofilm formation. The exposure of biofilm to 2 mM SAL induced a 27% reduction in the intracellular free Fe(2+) concentration compared with the controls. In addition, SAL depleted 23% of the available free Fe(2+) cation in culture media. These moderate iron-limited conditions promoted an intensification of biofilms formed by strain Newman and by S. aureus clinical isolates related to the USA300 and USA100 clones. The slight decrease in iron bioavailability generated by SAL was enough to induce the increase of PIA expression in biofilms formed by methicillin-resistant as well as methicillin-sensitive S. aureus strains. S. aureus did not produce capsular polysaccharide (CP) when it was forming biofilms under any of the experimental conditions tested. Furthermore, SAL diminished aconitase activity and stimulated the lactic fermentation pathway in bacteria forming biofilms. The polysaccharide composition of S. aureus biofilms was examined and FTIR spectroscopic analysis revealed a clear impact of SAL in a codY-dependent manner. Moreover, SAL negatively affected codY transcription in mature biofilms thus relieving the CodY repression of the ica operon. Treatment of mice with SAL induced a significant increase of S aureus colonization. It is suggested that the elevated PIA expression induced by SAL might be responsible for the high nasal

  15. The Active Component of Aspirin, Salicylic Acid, Promotes Staphylococcus aureus Biofilm Formation in a PIA-dependent Manner

    Science.gov (United States)

    Dotto, Cristian; Lombarte Serrat, Andrea; Cattelan, Natalia; Barbagelata, María S.; Yantorno, Osvaldo M.; Sordelli, Daniel O.; Ehling-Schulz, Monika; Grunert, Tom; Buzzola, Fernanda R.

    2017-01-01

    Aspirin has provided clear benefits to human health. But salicylic acid (SAL) -the main aspirin biometabolite- exerts several effects on eukaryote and prokaryote cells. SAL can affect, for instance, the expression of Staphylococcus aureus virulence factors. SAL can also form complexes with iron cations and it has been shown that different iron chelating molecules diminished the formation of S. aureus biofilm. The aim of this study was to elucidate whether the iron content limitation caused by SAL can modify the S. aureus metabolism and/or metabolic regulators thus changing the expression of the main polysaccharides involved in biofilm formation. The exposure of biofilm to 2 mM SAL induced a 27% reduction in the intracellular free Fe2+ concentration compared with the controls. In addition, SAL depleted 23% of the available free Fe2+ cation in culture media. These moderate iron-limited conditions promoted an intensification of biofilms formed by strain Newman and by S. aureus clinical isolates related to the USA300 and USA100 clones. The slight decrease in iron bioavailability generated by SAL was enough to induce the increase of PIA expression in biofilms formed by methicillin-resistant as well as methicillin-sensitive S. aureus strains. S. aureus did not produce capsular polysaccharide (CP) when it was forming biofilms under any of the experimental conditions tested. Furthermore, SAL diminished aconitase activity and stimulated the lactic fermentation pathway in bacteria forming biofilms. The polysaccharide composition of S. aureus biofilms was examined and FTIR spectroscopic analysis revealed a clear impact of SAL in a codY-dependent manner. Moreover, SAL negatively affected codY transcription in mature biofilms thus relieving the CodY repression of the ica operon. Treatment of mice with SAL induced a significant increase of S aureus colonization. It is suggested that the elevated PIA expression induced by SAL might be responsible for the high nasal colonization

  16. Identification of Fic-1 as an enzyme that inhibits bacterial DNA replication by AMPylating GyrB, promoting filament formation.

    Science.gov (United States)

    Lu, Canhua; Nakayasu, Ernesto S; Zhang, Li-Qun; Luo, Zhao-Qing

    2016-01-26

    The morphology of bacterial cells is important for virulence, evasion of the host immune system, and coping with environmental stresses. The widely distributed Fic proteins (filamentation induced by cAMP) are annotated as proteins involved in cell division because of the presence of the HPFx[D/E]GN[G/K]R motif. We showed that the presence of Fic-1 from Pseudomonas fluorescens significantly reduced the yield of plasmid DNA when expressed in Escherichia coli or P. fluorescens. Fic-1 interacted with GyrB, a subunit of DNA gyrase, which is essential for bacterial DNA replication. Fic-1 catalyzed the AMPylation of GyrB at Tyr(109), a residue critical for binding ATP, and exhibited auto-AMPylation activity. Mutation of the Fic-1 auto-AMPylated site greatly reduced AMPylation activity toward itself and toward GyrB. Fic-1-dependent AMPylation of GyrB triggered the SOS response, indicative of DNA replication stress or DNA damage. Fic-1 also promoted the formation of elongated cells when the SOS response was blocked. We identified an α-inhibitor protein that we named anti-Fic-1 (AntF), encoded by a gene immediately upstream of Fic-1. AntF interacted with Fic-1, inhibited the AMPylation activity of Fic-1 for GyrB in vitro, and blocked Fic-1-mediated inhibition of DNA replication in bacteria, suggesting that Fic-1 and AntF comprise a toxin-antitoxin module. Our work establishes Fic-1 as an AMPylating enzyme that targets GyrB to inhibit DNA replication and may target other proteins to regulate bacterial morphology.

  17. Steviol reduces MDCK Cyst formation and growth by inhibiting CFTR channel activity and promoting proteasome-mediated CFTR degradation.

    Directory of Open Access Journals (Sweden)

    Chaowalit Yuajit

    Full Text Available Cyst enlargement in polycystic kidney disease (PKD involves cAMP-activated proliferation of cyst-lining epithelial cells and transepithelial fluid secretion into the cyst lumen via cystic fibrosis transmembrane conductance regulator (CFTR chloride channel. This study aimed to investigate an inhibitory effect and detailed mechanisms of steviol and its derivatives on cyst growth using a cyst model in Madin-Darby canine kidney (MDCK cells. Among 4 steviol-related compounds tested, steviol was found to be the most potent at inhibiting MDCK cyst growth. Steviol inhibition of cyst growth was dose-dependent; steviol (100 microM reversibly inhibited cyst formation and cyst growth by 72.53.6% and 38.2±8.5%, respectively. Steviol at doses up to 200 microM had no effect on MDCK cell viability, proliferation and apoptosis. However, steviol acutely inhibited forskolin-stimulated apical chloride current in MDCK epithelia, measured with the Ussing chamber technique, in a dose-dependent manner. Prolonged treatment (24 h with steviol (100 microM also strongly inhibited forskolin-stimulated apical chloride current, in part by reducing CFTR protein expression in MDCK cells. Interestingly, proteasome inhibitor, MG-132, abolished the effect of steviol on CFTR protein expression. Immunofluorescence studies demonstrated that prolonged treatment (24 h with steviol (100 microM markedly reduced CFTR expression at the plasma membrane. Taken together, the data suggest that steviol retards MDCK cyst progression in two ways: first by directly inhibiting CFTR chloride channel activity and second by reducing CFTR expression, in part, by promoting proteasomal degradation of CFTR. Steviol and related compounds therefore represent drug candidates for treatment of polycystic kidney disease.

  18. Ni/γ-Al2O3 Catalyst for CO2 Reforming of Benzene as a Model Compound of Biomass Gasification Tar: Promotional Effect of Ultrasonic Treatment on Catalytic Performance

    Science.gov (United States)

    Li, B.; Chen, H. P.; Yang, H. P.; Yang, G. L.; Wang, X. H.; Zhang, S. H.

    This paper aims to understand the promotional effect of ultrasonic treatment on catalytic performance of Ni/γ-Al2O3 catalyst for CO2 reforming of benzene as a model compound of tar derived from biomass gasification, and the catalytic cracking mechanism was also discussed. Firstly, three Ni/γ-Al2O3catalysts were prepared by ultrasonic impregnation as the ultrasonic power variantat0, 120 and 500W, andthephysicochemical property of catalysts were characterized using N2-adsorption, SEM and XRD, etc. Then the catalytic performance of three catalysts for CO2 reforming of benzene wastestedin amicro-reactor.Theoutlet gaswas measured using a Micro-GC. Finally, the coking amount on the catalyst surface was measured by thermogravimetry (TG). The results showed that ultrasonic treatment significanüy modified the pore size distribution of the catalysts especiallyin theporesize range of 10-50nm andalso improved the capability of the coke resistance. It's beneficial to increase the lifetime of the catalyst. Meanwhile, lower ultrasonic power(120W) was more favorableto improve the coke resistance of the catalyst in the power range tested (120 and 500W). The main surface reactions over Ni/γ-Al2O3 catalysts included two steps: Firstly, benzeneadsorbed on the catalyst surface, the metal active sites dehydrogenation took place, and the residual molecule fragments (coke precursor) wouldcondense further which led to coke formation.Then, CO2 reacted with coke precursor and coke for coke elimination. The first step carriedout very quickly, and the second step was the rate-determining step.To reduce the cokedeposition on the catalyst surface, the performance of CO2 adsorption and activation and surface oxygen transmission capacity should be improved further.

  19. Selective laser melting Al-Si aluminum alloy and the crack formation mechanism%选区激光熔化成形Al-Si合金及其裂纹形成机制研究

    Institute of Scientific and Technical Information of China (English)

    王梦瑶; 朱海红; 祁婷; 张虎; 曾晓雁

    2016-01-01

    To get Al-Si alloy parts with high performance , the formation and cracking behaviors of Al-Si alloy parts fabricated by selective laser melting were studied .The relationship between process parameters and fabrication densification , and the mechanism of crack formation were revealed .The results show that the density of the fabricated samples increases at first and then decreases with the increase of laser power density .The cold cracks are formed in most of the samples which expand along the cladding layer .Its formation mechanism is that a large number of eutectic Si is formed during the process and eutectic Si reduces crack resistance strength of Al-Si aluminum alloy , and crack resistance cannot be enough to resist the high temperature gradient during the forming process , and the generated residual stress is the cause of cold cracks .By improving the process parameters , Al-Si alloy parts with high performance and without cracks could be formed .%为了得到性能良好的Al-Si合金零件,对选区激光熔化成形Al-Si合金的成形特性以及成形试样中裂纹进行了研究,得到了成形样致密度和工艺参量的关系以及裂纹的形成机制. 在合适的工艺区间内,随着激光能量密度的增大,致密度先上升后下降;大部分试样底部存在沿熔覆层扩展的冷裂纹;其形成机制是Al-Si合金粉末成形过程中,生成大量共晶Si相,使材料的抗裂性能不足以抵抗成形过程中的高温度梯度导致的残余应力所致. 结果表明,通过调整成形工艺参量,可以得到无裂纹的性能良好的成型零件.

  20. Biogas reforming on La-promoted NiMgAl catalysts derived from hydrotalcite-like precursors

    Science.gov (United States)

    Serrano-Lotina, A.; Rodríguez, L.; Muñoz, G.; Daza, L.

    Hydrotalcite-like precursors have been synthesized in order to study the influence of lanthanum on the structure and the properties of the precursors, as well as on the catalytic activity and stability of their derived catalyst on biogas reforming. From XRD, and TPO characterization, we confirmed that hydrotalcite-like precursors where obtained. After calcination at 750 °C, Mg(Ni,Al)O solid solution was detected. High surface areas have been obtained finding the highest surface area on the catalyst without lanthanum. TPR experiments were performed in order to study the reducibility of the catalysts. One reduction peak was found in the catalyst without lanthanum while two peaks were observed in the catalysts with lanthanum. A reduction peak at 900 °C was observed over the sample without Ni and La. Catalytic tests, at 700 °C with a feed of CH 4:CO 2 1:1, were performed after appropriate reduction during 50 h. While a decrease on catalytic activity was observed with the addition and the increase of La content, an enhancement in the stability was observed. No sign of deactivation of the catalyst and no carbon deposition were found on the catalysts doped with lanthanum.

  1. Formation of Sm sup 2 sup + ions in femtosecond laser excited Al sub 2 O sub 3 - SiO sub 2 glasses

    CERN Document Server

    Park, G J; Nogami, M

    2003-01-01

    Al sub 2 O sub 3 - SiO sub 2 glasses doped with Sm sup 3 sup + ions were irradiated with an 800 nm wavelength femtosecond laser pulse and the formation of Sm sup 2 sup + ions was investigated. The Sm sup 3 sup + ions were reduced to Sm sup 2 sup + within a few minutes of laser irradiation. Electron spin resonance spectra indicated that the hole was trapped in non-bridging oxygen bound to Al sup 3 sup + , while the electron was captured in the Sm sup 3 sup + , leading to the Sm sup 2 sup + formation. The thermal stability of the photoinduced Sm sup 2 sup + ions was also investigated by fluorescence spectroscopy. The Sm sup 2 sup + ions were converted to Sm sup 3 sup + ions by heating the glasses in air at 300- 400 deg. C.

  2. Platelet rich plasma promotes skeletal muscle cell migration in association with up-regulation of FAK, paxillin, and F-Actin formation.

    Science.gov (United States)

    Tsai, Wen-Chung; Yu, Tung-Yang; Lin, Li-Ping; Lin, Mioa-Sui; Tsai, Ting-Ta; Pang, Jong-Hwei S

    2017-02-24

    Platelet rich plasma (PRP) contains various cytokines and growth factors which may be beneficial to the healing process of injured muscle. The aim of this study was to investigate the effect and molecular mechanism of PRP on migration of skeletal muscle cells. Skeletal muscle cells intrinsic to Sprague-Dawley rats were treated with PRP. The cell migration was evaluated by transwell filter migration assay and electric cell-substrate impedance sensing. The spreading of cells was evaluated microscopically. The formation of filamentous actin (F-actin) cytoskeleton was assessed by immunofluorescence staining. The protein expressions of paxillin and focal adhesion kinase (FAK) were assessed by Western blot analysis. Transfection of paxillin small-interfering RNA (siRNAs) to muscle cells was performed to validate the role of paxillin in PRP-mediated promotion of cell migration. Dose-dependently PRP promotes migration of and spreading and muscle cells. Protein expressions of paxillin and FAK were up-regulated dose-dependently. F-actin formation was also enhanced by PRP treatment. Furthermore, the knockdown of paxillin expression impaired the effect of PRP to promote cell migration. It was concluded that PRP promoting migration of muscle cells is associated with up-regulation of proteins expression of paxillin and FAK as well as increasing F-actin formation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  3. The effects of B/(B+Al) ratio on glass formation regions and properties of phosphate edge-cladding glasses

    Institute of Scientific and Technical Information of China (English)

    Fenggang Zhao; Qinglei Dong; Lili Hu

    2007-01-01

    The glass-forming region of P2O5-Al2O3-B2O3-ZnO-Na2O-CuCl system with different Al2O3 and B2O3 contents was studied. The dependence of glasses properties on B/(B+Al) ratio was investigated. The absorption coefficient of copper ion in a specific glass was measured. These results are very helpful to the designing of a cladding glass for large size neodymium phosphate glass.

  4. Conversion of nuclear waste to molten glass: Formation of porous amorphous alumina in a high-Al melter feed

    Science.gov (United States)

    Xu, Kai; Hrma, Pavel; Washton, Nancy; Schweiger, Michael J.; Kruger, Albert A.

    2017-01-01

    The transition of Al phases in a simulated high-Al high-level nuclear waste melter feed heated at 5 K min-1 to 700 °C was investigated with transmission electron microscopy, 27Al nuclear magnetic resonance spectroscopy, the Brunauer-Emmett-Teller method, and X-ray diffraction. At temperatures between 300 and 500 °C, porous amorphous alumina formed from the dehydration of gibbsite, resulting in increased specific surface area of the feed (∼8 m2 g-1). The high-surface-area amorphous alumina formed in this manner could potentially stop salt migration in the cold cap during nuclear waste vitrification.

  5. Conversion of nuclear waste to molten glass: Formation of porous amorphous alumina in a high-Al melter feed

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kai; Hrma, Pavel R.; Washton, Nancy M.; Schweiger, Michael J.; Kruger, Albert A.

    2017-01-01

    The transition of Al phases in a simulated high-Al high-level nuclear waste melter feed heated at 5 K min-1 to 700°C was investigated with transmission electron microscopy, 27Al nuclear magnetic resonance spectroscopy, the Brunauer-Emmett-Teller method, and X-ray diffraction. At temperatures between 300 and 500°C, porous amorphous alumina formed from the dehydration of gibbsite, resulting in increased specific surface area of the feed (~8 m2 g-1). The high-surface-area amorphous alumina formed in this manner could potentially stop salt migration in the cold cap during nuclear waste vitrification.

  6. Effects of Ca Content on Formation and Photoluminescence Properties of CaAlSiN3:Eu2+ Phosphor by Combustion Synthesis

    Directory of Open Access Journals (Sweden)

    Shyan-Lung Chung

    2016-03-01

    Full Text Available Effects of Ca content (in the reactant mixture on the formation and the photoluminescence properties of CaAlSiN3:Eu2+ phosphor (CASIN were investigated by a combustion synthesis method. Ca, Al, Si, Eu2O3, NaN3, NH4Cl and Si3N4 powders were used as the starting materials and they were mixed and pressed into a compact which was then wrapped up with an igniting agent (i.e., Mg + Fe3O4. The compact was ignited by electrical heating under a N2 pressure of ≤1.0 MPa. By keeping the molar ratios of Al and Si (including the Si powder and the Si in Si3N4 powder both at 1.00 and that of Eu2O3 at 0.02, XRD (X-ray diffraction coupled with TEM-EDS (transmission electron microscope equipped with an energy-dispersive X-ray spectroscope and SAED (selected area electron diffraction measurements show that AlN:Eu2+ and Ca-α-SiAlON:Eu2+ are formed as the major phosphor products when the Ca molar ratio (denoted by Y is equal to 0.25 and AlN:Eu2+ and Ca-α-SiAlON:Eu2+ could not be detected at Y ≥ 0.75 and ≥1.00, respectively. CASIN (i.e., CaAlSiN3:Eu2+ becomes the only phosphor product as Y is increased to 1.00 and higher. The extent of formation of CASIN increases with increasing Y up to 1.50 and begins to decrease as Y is further increased to 1.68. While the excitation wavelength regions are similar at various Y, the emission wavelength regions vary significantly as Y is increased from 0.25 to 1.00 due to different combinations of phosphor phases formed at different Y. The emission intensity of CASIN was found to vary with Y in a similar trend to its extent of formation. The Ca and Eu contents (expressed as molar ratios in the synthesized products were found to increase roughly with increasing Y but were both lower than the respective Ca and Eu contents in the reactant mixtures.

  7. THE INFLUENCE OF HEAT TREATMENT WITH THE LIQUID PHASE ON FORMATION OF A MICROSTRUCTURE OF EUTECTIC Al-Si-ALLOY

    Directory of Open Access Journals (Sweden)

    A. Anikin

    2015-01-01

    Full Text Available The effect of heat treatment on the structure of the eutectic Al-Si-alloy, a theoretical substantiation process based on thermal analyzer and cooked microstructures was presented in this paper.

  8. Spontaneous formation of GaN/AlN core-shell nanowires on sapphire by hydride vapor phase epitaxy

    Science.gov (United States)

    Trassoudaine, Agnès; Roche, Elissa; Bougerol, Catherine; André, Yamina; Avit, Geoffrey; Monier, Guillaume; Ramdani, Mohammed Réda; Gil, Evelyne; Castelluci, Dominique; Dubrovskii, Vladimir G.

    2016-11-01

    Spontaneous GaN/AlN core-shell nanowires with high crystal quality were synthesized on sapphire substrates by vapor-liquid-solid hydride vapor phase epitaxy (VLS-HVPE) without any voluntary aluminum source. Deposition of aluminum is difficult to achieve in this growth technique which uses metal-chloride gaseous precursors: the strong interaction between the AlCl gaseous molecules and the quartz reactor yields a huge parasitic nucleation on the walls of the reactor upstream the substrate. We open up an innovative method to produce GaN/AlN structures by HVPE, thanks to aluminum etching from the sapphire substrate followed by redeposition onto the sidewalls of the GaN core. The paper presents the structural characterization of GaN/AlN core-shell nanowires, speculates on the growth mechanism and discusses a model which describes this unexpected behavior.

  9. Formation and Yield of Multi-Walled Carbon Nanotubes Synthesized via Chemical Vapour Deposition Routes Using Different Metal-Based Catalysts of FeCoNiAl, CoNiAl and FeNiAl-LDH

    Directory of Open Access Journals (Sweden)

    Mohd Zobir Hussein

    2014-11-01

    Full Text Available Multi-walled carbon nanotubes (MWCNTs were prepared via chemical vapor deposition (CVD using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs. Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs.

  10. The C. elegans DSB-2 protein reveals a regulatory network that controls competence for meiotic DSB formation and promotes crossover assurance.

    Science.gov (United States)

    Rosu, Simona; Zawadzki, Karl A; Stamper, Ericca L; Libuda, Diana E; Reese, Angela L; Dernburg, Abby F; Villeneuve, Anne M

    2013-01-01

    For most organisms, chromosome segregation during meiosis relies on deliberate induction of DNA double-strand breaks (DSBs) and repair of a subset of these DSBs as inter-homolog crossovers (COs). However, timing and levels of DSB formation must be tightly controlled to avoid jeopardizing genome integrity. Here we identify the DSB-2 protein, which is required for efficient DSB formation during C. elegans meiosis but is dispensable for later steps of meiotic recombination. DSB-2 localizes to chromatin during the time of DSB formation, and its disappearance coincides with a decline in RAD-51 foci marking early recombination intermediates and precedes appearance of COSA-1 foci marking CO-designated sites. These and other data suggest that DSB-2 and its paralog DSB-1 promote competence for DSB formation. Further, immunofluorescence analyses of wild-type gonads and various meiotic mutants reveal that association of DSB-2 with chromatin is coordinated with multiple distinct aspects of the meiotic program, including the phosphorylation state of nuclear envelope protein SUN-1 and dependence on RAD-50 to load the RAD-51 recombinase at DSB sites. Moreover, association of DSB-2 with chromatin is prolonged in mutants impaired for either DSB formation or formation of downstream CO intermediates. These and other data suggest that association of DSB-2 with chromatin is an indicator of competence for DSB formation, and that cells respond to a deficit of CO-competent recombination intermediates by prolonging the DSB-competent state. In the context of this model, we propose that formation of sufficient CO-competent intermediates engages a negative feedback response that leads to cessation of DSB formation as part of a major coordinated transition in meiotic prophase progression. The proposed negative feedback regulation of DSB formation simultaneously (1) ensures that sufficient DSBs are made to guarantee CO formation and (2) prevents excessive DSB levels that could have deleterious

  11. Near-Barrierless Ammonium Bisulfate Formation via a Loop-Structure Promoted Proton-Transfer Mechanism on the Surface of Water.

    Science.gov (United States)

    Li, Lei; Kumar, Manoj; Zhu, Chongqin; Zhong, Jie; Francisco, Joseph S; Zeng, Xiao Cheng

    2016-02-17

    In the atmosphere, a well-known and conventional pathway toward the formation of ammonium sulfate is through the neutralization of sulfuric acid with ammonia (NH3) in water droplets. Here, we present direct ab initio molecular dynamics simulation evidence of the formation of ammonium bisulfate (NH4HSO4) from the hydrated NH3 and SO3 molecules in a water trimer as well as on the surface of a water droplet. This reaction suggests a new mechanism for the formation of ammonium sulfate in the atmosphere, especially when the concentration of NH3 is high (e.g., ∼10 μg m(-3)) in the air. Contrary to the water monomer and dimer, the water trimer enables near-barrierless proton transfer via the formation of a unique loop structure around the reaction center. The formation of the loop structure promotes the splitting of a water molecule in the proton-transfer center, resulting in the generation a NH4(+)/HSO4(-) ion pair. The loop-structure promoted proton-transfer mechanism is expected to be ubiquitous on the surface of cloud droplets with adsorbed NH3 and SO3 molecules and, thus, may play an important role in the nucleation of aerosol particles (e.g., fine particles PM2.5) in water droplets.

  12. Parent and Clinician Preferences for an Asthma App to Promote Adolescent Self-Management: A Formative Study

    Science.gov (United States)

    Roberts, Courtney A; Sage, Adam J; Coyne-Beasley, Tamera; Sleath, Betsy L; Carpenter, Delesha M

    2016-01-01

    Background Most youth asthma apps are not designed with parent and clinician use in mind, and rarely is the app development process informed by parent or clinician input. Objective This study was conducted to generate formative data on the use, attitudes, and preferences for asthma mHealth app features among parents and clinicians, the important stakeholders who support adolescents with asthma and promote adolescent self-management skills. Methods We conducted a mixed-methods study from 2013 to 2014 employing a user-centered design philosophy to acquire feedback from a convenience sample of 20 parents and 6 clinicians. Participants were given an iPod Touch and asked to evaluate 10 features on 2 existing asthma apps. Participant experiences using the apps were collected from questionnaires and a thematic analysis of audio-recorded and transcribed (verbatim) interviews using MAXQDA. Descriptive statistics were calculated to characterize the study sample and app feature feedback. Independent samples t tests were performed to compare parent and clinician ratings of app feature usefulness (ratings: 1=not at all useful to 5=very useful). Results All parents were female (n=20), 45% were black, 20% had an income ≥US $50,000, and 45% had a bachelor’s degree or higher education. The clinician sample included 2 nurses and 4 physicians with a mean practice time of 13 years. Three main themes provided an understanding of how participants perceived their roles and use of asthma app features to support adolescent asthma self-management: monitoring and supervision, education, and communication/information sharing. Parents rated the doctor report feature highest, and clinicians rated the doctor appointment reminder highest of all evaluated app features on usefulness. The peak flow monitoring feature was the lowest ranked feature by both parents and clinicians. Parents reported higher usefulness for the doctor report (t(10)=2.7, Pdesigned to help support youth asthma management

  13. Effects of oxygen plasma treatment on the formation of ohmic contacts to GaN and AlGaN

    Energy Technology Data Exchange (ETDEWEB)

    Yan, J.; Kappers, M.J.; McAleese, C.; Humphreys, C.J. [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Crossley, A. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Phillips, W.A. [phconsult Ltd., 54 Convent Garden, Cambridge CB1 2HR (United Kingdom)

    2004-10-01

    The effects of oxygen plasma treatment prior to metal contact deposition have been studied for both n- and p-GaN, as well as n-AlGaN. In n-GaN, the as-deposited Ti/Al contacts change from rectifying to ohmic, and further improvements are observed after rapid thermal annealing (RTA). A specific contact resistivity better than 10{sup -7} {omega} cm{sup 2} was obtained using a plasma treatment of 20 s at 30 W and 0.2 mbar, followed by RTA at 500 C in argon. The I-V characteristics of the Ti/Al contacts degraded when plasma treatments were performed for a longer time and/or at increased plasma pressure. However, in contrast to n-GaN, the electrical properties of the Ni/Au contacts to p-GaN and Ti/Al contacts to n-Al{sub 0.15}Ga{sub 0.85}N deteriorated following oxygen plasma treatment. X-ray photoelectron spectroscopy (XPS) was used in order to help elucidate the mechanisms behind these effects. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Matrix metalloproteinase inhibition delays wound healing and blocks the latent transforming growth factor-beta1-promoted myofibroblast formation and function

    DEFF Research Database (Denmark)

    Mirastschijski, Ursula; Schnabel, Reinhild; Claes, Juliane

    2010-01-01

    The ability to regulate wound contraction is critical for wound healing as well as for pathological contractures. Matrix metalloproteinases (MMPs) have been demonstrated to be obligatory for normal wound healing. This study examined the effect that the broad-spectrum MMP inhibitor BB-94 has when...... applied topically to full-thickness skin excisional wounds in rats and its ability to inhibit the promotion of myofibroblast formation and function by the latent transforming-growth factor-beta1 (TGF-beta1). BB-94 delayed wound contraction, as well as all other associated aspects of wound healing examined...... and may explain why wound contraction and other associated events of wound healing were only delayed and not completely inhibited. BB-94 was also found to inhibit the ability of latent TGF-beta1 to promote the formation and function of myofibroblasts. These results suggest that BB-94 could delay wound...

  15. Al and Ge simultaneous oxidation using neutral beam post-oxidation for formation of gate stack structures

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, Takeo, E-mail: t-ohno@wpi-aimr.tohoku.ac.jp [WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Nakayama, Daiki [Institute of Fluid Science (IFS), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Samukawa, Seiji, E-mail: samukawa@ifs.tohoku.ac.jp [WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Institute of Fluid Science (IFS), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2015-09-28

    To obtain a high-quality Germanium (Ge) metal–oxide–semiconductor structure, a Ge gate stacked structure was fabricated using neutral beam post-oxidation. After deposition of a 1-nm-thick Al metal film on a Ge substrate, simultaneous oxidation of Al and Ge was carried out at 300 °C, and a Ge oxide film with 29% GeO{sub 2} content was obtained by controlling the acceleration bias power of the neutral oxygen beam. In addition, the fabricated AlO{sub x}/GeO{sub x}/Ge structure achieved a low interface state density of less than 1 × 10{sup 11 }cm{sup −2 }eV{sup −1} near the midgap.

  16. Support vector regression-guided unravelling: antioxidant capacity and quantitative structure-activity relationship predict reduction and promotion effects of flavonoids on acrylamide formation

    Science.gov (United States)

    Huang, Mengmeng; Wei, Yan; Wang, Jun; Zhang, Yu

    2016-09-01

    We used the support vector regression (SVR) approach to predict and unravel reduction/promotion effect of characteristic flavonoids on the acrylamide formation under a low-moisture Maillard reaction system. Results demonstrated the reduction/promotion effects by flavonoids at addition levels of 1-10000 μmol/L. The maximal inhibition rates (51.7%, 68.8% and 26.1%) and promote rates (57.7%, 178.8% and 27.5%) caused by flavones, flavonols and isoflavones were observed at addition levels of 100 μmol/L and 10000 μmol/L, respectively. The reduction/promotion effects were closely related to the change of trolox equivalent antioxidant capacity (ΔTEAC) and well predicted by triple ΔTEAC measurements via SVR models (R: 0.633-0.900). Flavonols exhibit stronger effects on the acrylamide formation than flavones and isoflavones as well as their O-glycosides derivatives, which may be attributed to the number and position of phenolic and 3-enolic hydroxyls. The reduction/promotion effects were well predicted by using optimized quantitative structure-activity relationship (QSAR) descriptors and SVR models (R: 0.926-0.994). Compared to artificial neural network and multi-linear regression models, SVR models exhibited better fitting performance for both TEAC-dependent and QSAR descriptor-dependent predicting work. These observations demonstrated that the SVR models are competent for predicting our understanding on the future use of natural antioxidants for decreasing the acrylamide formation.

  17. Formation of a 25 mol% Fe2O3-Al2O3 solid solution prepared by ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Mørup, Steen; Linderoth, Søren

    1996-01-01

    The phase transformation process of a 25 mol% Fe2O3-Al2O3 powder mixture during high-energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. A metastable solid solution of 25 mol % Fe2O3 in Al2O3 with corundum structure has successfully been prepared after a milling...... time of 122 h. This demonstrates that the high-energy ball milling technique is able to prepare metastable solid solutions with an extended range of compositions in ceramic/ceramic systems with a positive hear of mixing....

  18. A Study of Adherent Oxide Formation

    Science.gov (United States)

    1983-10-01

    improve oxide scale adherence to NiCrAl were investigated. Laser-processed materials were isothermally and cyclically oxidized and oxide scale...modified NiCrAl altered the morphology of the alumina scale and promoted the formation of a thinner, dense protective layer. • Thin aluminum oxide films...6 A. Materials. ........................... 6 B. Oxidation Studies. ....................... 7 1. NiCrAl .. .......................... 7a2

  19. Injectable hydrogel promotes early survival of induced pluripotent stem cell-derived oligodendrocytes and attenuates longterm teratoma formation in a spinal cord injury model.

    Science.gov (United States)

    Führmann, T; Tam, R Y; Ballarin, B; Coles, B; Elliott Donaghue, I; van der Kooy, D; Nagy, A; Tator, C H; Morshead, C M; Shoichet, M S

    2016-03-01

    Transplantation of pluripotent stem cells and their differentiated progeny has the potential to preserve or regenerate functional pathways and improve function after central nervous system injury. However, their utility has been hampered by poor survival and the potential to form tumors. Peptide-modified biomaterials influence cell adhesion, survival and differentiation in vitro, but their effectiveness in vivo remains uncertain. We synthesized a peptide-modified, minimally invasive, injectable hydrogel comprised of hyaluronan and methylcellulose to enhance the survival and differentiation of human induced pluripotent stem cell-derived oligodendrocyte progenitor cells. Cells were transplanted subacutely after a moderate clip compression rat spinal cord injury. The hydrogel, modified with the RGD peptide and platelet-derived growth factor (PDGF-A), promoted early survival and integration of grafted cells. However, prolific teratoma formation was evident when cells were transplanted in media at longer survival times, indicating that either this cell line or the way in which it was cultured is unsuitable for human use. Interestingly, teratoma formation was attenuated when cells were transplanted in the hydrogel, where most cells differentiated to a glial phenotype. Thus, this hydrogel promoted cell survival and integration, and attenuated teratoma formation by promoting cell differentiation.

  20. The small heat shock protein B8 (HspB8) promotes autophagic removal of misfolded proteins involved in amyotrophic lateral sclerosis (ALS)

    NARCIS (Netherlands)

    Crippa, Valeria; Sau, Daniela; Rusmini, Paola; Boncoraglio, Alessandra; Onesto, Elisa; Bolzoni, Elena; Galbiati, Mariarita; Fontana, Elena; Marino, Marianna; Carra, Serena; Bendotti, Caterina; De Biasi, Silvia; Poletti, Angelo

    2010-01-01

    Several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), are characterized by the presence of misfolded proteins, thought to trigger neurotoxicity. Some familial forms of ALS (fALS), clinically indistinguishable from sporadic ALS (sALS), are linked to superoxide dismutase 1

  1. Formation of abrasion-resistant coatings of the AlSiFexMny intermetallic compound type on the AISI 304L alloy

    Directory of Open Access Journals (Sweden)

    Martínez-Perales, Laura G.

    2016-03-01

    Full Text Available The α-Al9FeMnSi and β-Al9FeMn2Si intermetallics formed by reactive sintering of Al, Si, Mn, Fe, Cr and Ni powders have been used in AISI 304L steels to enhance microhardness. Processing variables of the reactive sintering treatment were temperature (600, 650, 700, 750 and 800 °C, pressure (5, 10 y 20 MPa and holding time (3600, 5400 y 7200 seconds. Experimental results show that temperature is the most important variable affecting the substrate/coating formation, while pressure does not appear to have a significant effect. The results show the optimum conditions of the reactive sintering that favor the substrate/coating formation are 800 °C, 20 MPa and 7200 seconds. Under these conditions, the reaction zone between the substrate and coating is more compacted and well-adhered, with a microhardness of 1300 Vickers. The results of SEM and X-Ray diffraction confirmed the formation of α-Al9FeMnSi and β-Al9FeMn2Si intermetallics in the substrate/coating interface as well as the presence of Cr and Ni, indicating diffusion of these two elements from the substrate to the interface.Los intermetálicos α-Al9FeMnSi y β-Al9FeMn2Si formados por sinterización reactiva de polvos Al, Si, Mn, Fe, Cr, Ni se han utilizado en aceros AISI 304L para mejorar la microdureza. Las variables de procesamiento de sinterización reactiva fueron temperatura (600, 650, 700, 750, y 800 °C, presión (5, 10 y 20 MPa y el tiempo de retención (3600, 5400 7200 segundos. Los resultados experimentales muestran que la temperatura es la variable más importante que afecta a la formación del sustrato/recubrimiento, mientras que la presión no parece tener un efecto significativo una influencia significativa. Los resultados muestran las condiciones óptimas de la sinterización reactiva que favorecen la formación del sustrato/recubrimiento a 800 °C, 20 MPa y 7200 segundos. En estas condiciones, la zona de reacción entre el sustrato y el recubrimiento es más compacta y bien

  2. The role of Al in the formation of secondary Ni precipitates on pyrophyllite, gibbsite, talc, and amorphous silica: a DRS study

    Science.gov (United States)

    Scheinost, Andreas C.; Ford, Robert G.; Sparks, Donald L.

    1999-10-01

    Formation of secondary Ni precipitates is an important mechanism of Ni retention in neutral and alkaline clay/water systems. However, the structure and composition of these secondary phases, and their stability is still disputable. Using existing structure refinement data and new ab-initio FEFF 7 calculations we show that Ni-edge X-ray absorption fine structure spectroscopy alone may not be able to unequivocally discriminate four possible candidate compounds: α-Ni(OH)2, the isostructural but Al-substituted layered double hydroxide (Ni-Al LDH), and 1:1 and 2:1 Ni-containing phyllosilicates. Hence, we investigated the potential of diffuse reflectance spectroscopy (DRS) in determining in situ the Ni phase forming in the presence of four sorbents, pyrophyllite, talc, gibbsite, and amorphous silica. The 3A2g → 3T1g(F) band (ν2) of octahedrally coordinated Ni2+ could be reliably extracted from the reflectance spectra of wet pastes. In the presence of the Al-free talc and amorphous silica, the ν2 band was at ≈14,900 cm-1, but shifted to 15,300 cm-1 in the presence of Al-containing pyrophyllite and gibbsite. This shift suggests that Al is dissolved from the sorbent and substitutes for Ni in brucite-like hydroxide layers of the newly forming precipitate phase, causing a decrease of the Ni-O distances and, in turn, an increase of the crystal-field splitting energy. Comparison with Ni model compounds showed that the band at 14,900 cm-1 is a unique fingerprint of α-Ni(OH)2, and the band at 15,300 cm-1 of Ni-Al LDH. Although the complete transformation of α-Ni(OH)2 into a Ni phyllosilicate causes a significant contraction of the Ni hydroxide sheet as indicated by band positions intermediate to those of α-Ni(OH)2 and Ni-Al LDH, incipient states of silication do not influence Ni-O distances and cannot be detected by DRS. The first evidence for the formation of a precipitate was obtained after 5 min (pyrophyllite), 7 hr (talc), 24 hr (gibbsite), and 3 days (amorphous

  3. Microstructure and formation mechanism of titanium matrix composites coating on Ti-6Al-4V by laser cladding

    Institute of Scientific and Technical Information of China (English)

    CAI Lifang; ZHANG Yongzhong; SHI Likai

    2007-01-01

    Laser cladding experiments were done on a 5-kW continuous wave CO2 laser to synthesize TiC and TiB reinforced titanium matrix composite coatings on Ti-6Al-4V alloy with a mixture of Ti and B4C precursor powder. The thermodynamics of the reactions were calculated and analyzed. The microstructure and phase evolution of TiB and TiC composites were investigated. The results showed that the chemical reaction between Ti and B4C would release much heat, and these compounds, TiC, TiB, and small amount of TiB2, can be formed on the surface of Ti-6Al-4V alloy if the supplied energy is sufficient to excite the reaction among the initial products. A good metallurgical bond between the coating and the substrate can be achieved. The microhardness of coating was irregular and the maximum value was approximately HV600.

  4. In situ formation of CA[sub 6] platelets in Al[sub 2]O[sub 3] and Al[sub 2]O[sub 3]/ZrO[sub 2] matrices

    Energy Technology Data Exchange (ETDEWEB)

    Belmonte, M. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Sanchez-Herencia, A.J. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Moreno, R. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Miranzo, P. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Moya, J.S. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain)); Tomsia, A.P. (Inst. de Ceramica y Vidrio (CSIC), Madrid (Spain) Lawrence Berkeley Lab. and U.C. Berkeley, CA (United States))

    1993-11-01

    Al[sub 2]O[sub 3] and Al[sub 2]O[sub 3]/ZrO[sub 2] compacts containing CaO as a dopant have been sintered under different conditions and atmospheres: air, high vacuum (> 10[sup -6]torr). SEM observations have been made on the polished surfaces of sintered and also of annealed samples. Only after the annealing treatment in air at temperatures ranging from 1400 to 1500 C, a massive formation of CA[sub 6] platelets was detected in samples sintered in low oxygen partial pressure atmospheres. In order to clarify the mechanism of formation of this secondary phase at the grain boundaries, CaO has been introduced in the form of either plaster of Paris (to reproduce a possible contamination provided by the molds in slip casting) or CaCO[sub 3]. The obtained results indicate the important role of the firing atmosphere on the precipitation of secondary phases at grain boundary. (orig.).

  5. Relative crystal stability of Al{sub x}FeNiCrCo high entropy alloys from XRD analysis and formation energy calculation

    Energy Technology Data Exchange (ETDEWEB)

    Jasiewicz, K.; Cieslak, J.; Kaprzyk, S.; Tobola, J., E-mail: tobola@ftj.agh.edu.pl

    2015-11-05

    Electronic structure of Al{sub x}FeNiCrCo (x ≤ 3) high-entropy alloys (HEAs) was calculated using the Korringa–Kohn–Rostoker method combined with the coherent potential approximation (KKR-CPA). Total energy minimization was performed for bcc and fcc structures in each alloy composition. The phase stability was investigated from the total energy analysis, which finally allowed to determine the bcc–fcc phase transition for aluminium concentration close to 13 at%. It inspired us to synthesize Al{sub x}FeNiCrCo (0 ≤ x ≤ 1.5) using two procedures based on arc melting and sintering to allow for observation of entropy effect on phase formation. The XRD measurements evidently proved an occurence of fcc or bcc structure and their coexistence, depending on Al concentration and temperature. This finding remains in good agreement with theoretical results from free energy analysis, when accounting for KKR-CPA total energy as well as entropy terms. Furthermore, the structure preference, from fcc to bcc HEAs, with increasing Al content was discussed in view of total and atomic-dependent density of states computed in non-magnetic and paramagnetic-like states. - Highlights: • Crystal stability and electronic properties of high entropy alloys from KKR-CPA. • Influence of configuration entropy on phase preference (or coexistence). • Effect of configuration entropy on phase stability: arc melting viz. sintering. • Ab initio calculations (accounting for disorder) of phase preference in HEA.

  6. Formation Process and Properties of Ohmic Contacts Containing Molybdenum to AlGaN/GaN Heterostructures

    Directory of Open Access Journals (Sweden)

    Wojciech Macherzynski

    2016-01-01

    Full Text Available Properties of wide bandgap semiconductors as chemical inertness to harsh conditions and possibility of working at high temperature ensure possible applications in the field as military, aerospace, automotive, engine monitoring, flame detection and solar UV detection. Requirements for ohmic contacts in semiconductor devices are determined by the proposed application. These contacts to AlGaN/GaN heterostructure for application as high temperature, high frequency and high power devices have to exhibit good surface morphology and low contact resistance. The latter is a crucial factor in limiting the development of high performance AlGaN/GaN devices. Lowering of the resistance is assured by rapid thermal annealing process. The paper present studies of Ti/Al/Mo/Au ohmic contacst annealed at temperature range from 825°C to 885°C in N2 atmosphere. The electrical parameters of examined samples as a function of the annealing process condition have been studied. Initially the annealing temperature increase caused lowering of the contacts resistance. The lowest value was noticed for the temperature of annealing equal to 885°C. Further increase of annealing temperature led to deterioration of contact resistance of investigated ohmic contacts.

  7. Al/Fe isomorphic substitution versus Fe{sub 2}O{sub 3} clusters formation in Fe-doped aluminosilicate nanotubes (imogolite)

    Energy Technology Data Exchange (ETDEWEB)

    Shafia, Ehsan [Politecnico di Torino, Department of Applied Science and Technology and INSTM Unit of Torino-Politecnico (Italy); Esposito, Serena [Università degli Studi di Cassino e del Lazio Meridionale, Department of Civil and Mechanical Engineering (Italy); Manzoli, Maela; Chiesa, Mario [Università di Torino, Dipartimento di Chimica and Centro Interdipartimentale NIS (Italy); Tiberto, Paola [Electromagnetism, I.N.Ri.M. (Italy); Barrera, Gabriele [Università di Torino, Dipartimento di Chimica and Centro Interdipartimentale NIS (Italy); Menard, Gabriel [Harvard University, Department of Chemistry and Chemical Biology (United States); Allia, Paolo, E-mail: paolo.allia@polito.it [Politecnico di Torino, Department of Applied Science and Technology and INSTM Unit of Torino-Politecnico (Italy); Freyria, Francesca S. [Massachusetts Institute of Technology, Department of Chemistry (United States); Garrone, Edoardo; Bonelli, Barbara, E-mail: barbara.bonelli@polito.it [Politecnico di Torino, Department of Applied Science and Technology and INSTM Unit of Torino-Politecnico (Italy)

    2015-08-15

    Textural, magnetic and spectroscopic properties are reported of Fe-doped aluminosilicate nanotubes (NTs) of the imogolite type, IMO, with nominal composition (OH){sub 3}Al{sub 2−x}Fe{sub x}O{sub 3}SiOH (x = 0, 0.025, 0.050). Samples were obtained by either direct synthesis (Fe-0.025-IMO, Fe-0.050-IMO) or post-synthesis loading (Fe-L-IMO). The Fe content was either 1.4 wt% (both Fe-0.050-IMO and Fe-L-IMO) or 0.7 wt% (Fe-0.025-IMO). Textural properties were characterized by High-Resolution Transmission Electron Microscopy, X-ray diffraction and N{sub 2} adsorption/desorption isotherms at 77 K. The presence of different iron species was studied by magnetic moment measurements and three spectroscopies: Mössbauer, UV–Vis and electron paramagnetic resonance, respectively. Fe{sup 3+}/Al{sup 3+} isomorphic substitution (IS) at octahedral sites at the external surface of NTs is the main process occurring by direct synthesis at low Fe loadings, giving rise to the formation of isolated high-spin Fe{sup 3+} sites. Higher loadings give rise, besides IS, to the formation of Fe{sub 2}O{sub 3} clusters. IS occurs up to a limit of Al/Fe atomic ratio of ca. 60 (corresponding to x = 0.032). A fraction of the magnetism related to NCs is pinned by the surface anisotropy; also, clusters are magnetically interacting with each other. Post-synthesis loading leads to a system rather close to that obtained by direct synthesis, involving both IS and cluster formations. Slightly larger clusters than with direct synthesis samples, however, are formed. The occurrence of IS indicates a facile cleavage/sealing of Al–O–Al bonds: this opens the possibility to exchange Al{sup 3+} ions in pre-formed IMO NTs, a much simpler procedure compared with direct synthesis.

  8. Plasma Formation and Evolution on Cu, Al, Ti, and Ni Surfaces Driven by a Mega-Ampere Current Pulse

    Science.gov (United States)

    Yates, Kevin C.

    Metal alloy mm-diameter rods have been driven by a 1-MA, 100-ns current pulse from the Zebra z-pinch. The intense current produces megagauss surface magnetic fields that diffuse into the load, ohmically heating the metal until plasma forms. Because the radius is much thicker than the skin depth, the magnetic field reaches a much higher value than around a thin-wire load. With the "barbell" load design, plasma formation in the region of interest due to contact arcing or electron avalanche is avoided, allowing for the study of ohmically heated loads. Work presented here will show first evidence of a magnetic field threshold for plasma formation in copper 101, copper 145, titanium, and nickel, and compare with previous work done with aluminum. Copper alloys 101 and 145, titanium grade II, and nickel alloy 200 form plasma when the surface magnetic field reaches 3.5, 3.0, 2.2, and 2.6 megagauss, respectively. Varying the element metal, as well as the alloy, changes multiple physical properties of the load and affects the evolution of the surface material through the multiple phase changes. Similarities and differences between these metals will be presented, giving motivation for continued work with different material loads. During the current rise, the metal is heated to temperatures that cause multiple phase changes. When the surface magnetic field reaches a threshold, the metal ionizes and the plasma becomes pinched against the underlying cooler, dense material. Diagnostics fielded have included visible light radiometry, two-frame shadowgraphy (266 and 532 nm wavelengths), time-gated EUV spectroscopy, single-frame/2ns gated imaging, and multi-frame/4ns gated imaging with an intensified CCD camera (ICCD). Surface temperature, expansion speeds, instability growth, time of plasma formation, and plasma uniformity are determined from the data. The time-period of potential plasma formation is scrutinized to understand if and when plasma forms on the surface of a heated

  9. Paleoecology of Benthic Foraminifera in Coral Reefs Recorded in the Jurassic Tuwaiq Mountain Formation of the Khashm Al-Qaddiyah Area, Central Saudi Arabia

    Institute of Scientific and Technical Information of China (English)

    Mohamed Youssef; Abdelbaset S El-Sorogy

    2015-01-01

    Thirty three benthic foraminiferal species belong to 23 genera and 16 families have been recorded from the coral reefs of the Callovian Tuwaiq Formation, Khashm Al-Qaddiyah area, Central Saudi Arabia. Three species:Astacolus qaddiyahensis, Nodosaria riyadhensis, Siderolites jurassica are believed to be new. Nearly all identified foraminifera are of Atlantic-Miditeranean affinity. The fo-raminiferal assemblage recorded in the present work is mixed of open marine, moderately deep ma-rine conditions associations and shallow to deep lagoon. The reefal part of upper Twiaq Formation may have been deposited in shallow water of lower to middle shelf depth (20–50 m) as indicated by abundant corals and benthic foraminifera. The coral fauna and bearing benthic foraminifera indi-cated moderate water energy.

  10. Self-assembled growth of GaN nanowires on amorphous Al x O y : from nucleation to the formation of dense nanowire ensembles.

    Science.gov (United States)

    Sobanska, M; Fernández-Garrido, S; Zytkiewicz, Z R; Tchutchulashvili, G; Gieraltowska, S; Brandt, O; Geelhaar, L

    2016-08-12

    We present a comprehensive description of the self-assembled nucleation and growth of GaN nanowires (NWs) by plasma-assisted molecular beam epitaxy on amorphous Al x O y buffers (a-Al x O y ) prepared by atomic layer deposition. The results are compared with those obtained on nitridated Si(111). Using line-of-sight quadrupole mass spectrometry, we analyze in situ the incorporation of Ga starting from the incubation and nucleation stages till the formation of the final nanowire ensemble and observe qualitatively the same time dependence for the two types of substrates. However, on a-Al x O y the incubation time is shorter and the nucleation faster than on nitridated Si. Moreover, on a-Al x O y we observe a novel effect of decrease in incorporated Ga flux for long growth durations which we explain by coalescence of NWs leading to reduction of the GaN surface area where Ga may reside. Dedicated samples are used to analyze the evolution of surface morphology. In particular, no GaN nuclei are detected when growth is interrupted during the incubation stage. Moreover, for a-Al x O y , the same shape transition from spherical cap-shaped GaN crystallites to the NW-like geometry is found as it is known for nitridated Si. However, while the critical radius for this transition is only slightly larger for a-Al x O y than for nitridated Si, the critical height is more than six times larger for a-Al x O y . Finally, we observe that in fully developed NW ensembles, the substrate no longer influences growth kinetics and the same N-limited axial growth rate is measured on both substrates. We conclude that the same nucleation and growth processes take place on a-Al x O y as on nitridated Si and that these processes are of a general nature. Quantitatively, nucleation proceeds somewhat differently, which indicates the influence of the substrate, but once shadowing limits growth processes to the upper part of the NW ensemble, they are not affected anymore by the type of substrate.

  11. G4-DNA Formation in the HRAS Promoter and Rational Design of Decoy Oligonucleotides for Cancer Therapy

    DEFF Research Database (Denmark)

    Membrino, Alexandro; Cogoi, Susanna; Pedersen, Erik Bjerregaard;

    2011-01-01

    HRAS is a proto-oncogene involved in the tumorigenesis of urinary bladder cancer. In the HRAS promoter we identified two G-rich elements, hras-1 and hras-2, that fold, respectively, into an antiparallel and a parallel quadruplex (qhras-1, qhras-2). When we introduced in sequence hras-1 or hras-2...

  12. EPFR formation from phenol adsorption on Al{sub 2}O{sub 3} and TiO{sub 2}: EPR and EELS studies

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Matthew C., E-mail: mpatt15@tigers.lsu.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Keilbart, Nathan D., E-mail: kei07001@byui.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Department of Mechanical Engineering, Brigham Young University-Idaho, Rexburg, ID 83460 (United States); Kiruri, Lucy W., E-mail: lkirur1@tigers.lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Thibodeaux, Chad A., E-mail: cthib19@tigers.lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Lomnicki, Slawo, E-mail: slomni1@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Kurtz, Richard L., E-mail: rlkurtz@lsu.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Poliakoff, E.D., E-mail: epoliak@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Dellinger, Barry, E-mail: barryd@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Sprunger, Phillip T., E-mail: phils@lsu.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2013-08-30

    Highlights: ► EPR studies of phenol adsorption on titania and alumina show radical formation at 505 K. ► EELS of phenol/TiO{sub 2}(1 1 0) at 90 K show π–π{sup ∗} transitions from intact molecule. ► EELS of phenol/TiO{sub 2}(1 1 0) and phenol/alumina adsorbed at 525 K show shift in π–π{sup ∗}. ► Shifted π–π{sup ∗} on single crystal corresponds to radical formation conditions in EPR. - Abstract: We have examined the formation of environmentally persistent free radicals (EPFRs) from phenol over alumina and titania using both powder and single-crystal samples. Electron paramagnetic resonance (EPR) studies of phenol adsorbed on metal oxide powders indicates radical formation on both titania and alumina, with both oxides forming one faster-decaying species (lifetime on the order of 50–100 h) and one slower-decaying species (lifetimes on the order of 1000 h or more). Electron energy loss spectroscopy (EELS) measurements comparing physisorbed phenol on single-crystal TiO{sub 2}(1 1 0) to phenoxyl radicals on the same substrate indicate distinct changes in the π–π{sup ∗} transitions from phenol after radical formation. The identical shifts are observed from EELS studies of phenoxyl radicals on ultrathin alumina grown on NiAl(1 1 0), indicating that this shift in the π–π{sup ∗} transition may be taken as a general hallmark of phenoxyl radical formation.

  13. Promotion of peripheral nerve regeneration and prevention of neuroma formation by PRGD/PDLLA/β-TCP conduit: report of two cases.

    Science.gov (United States)

    Yin, Yixia; Li, Binbin; Yan, Qiongjiao; Dai, Honglian; Wang, Xinyu; Huang, Jifeng; Li, Shipu

    2015-06-01

    In the field of nerve repair, one major challenge is the formation of neuroma. However, reports on both the promotion of nerve regeneration and prevention of traumatic neuroma in the clinical settings are rare in the field of nerve repair. One of the reasons could be the insufficiency in the follow-up system. We have conducted 33 cases of nerve repair using PRGD/PDLLA/β-TCP conduit without any sign of adverse reaction, especially no neuroma formation. Among them, we have selected two cases as representatives to report in this article. The first case was a patient with an upper limb nerve wound was bridged by PRGD/PDLLA/β-TCP conduit and a plate fixation was given. After nearly 3-years' follow-up, the examination results demonstrated that nerve regeneration effect was very good. When the reoperation was performed to remove the steel plate we observed a uniform structure of the regenerated nerve without the formation of neuroma, and to our delight, the implanted conduit was completely degraded 23 months after the implantation. The second case had an obsolete nerve injury with neuroma formation. After removal of the neuroma, the nerve was bridged by PRGD/PDLLA/β-TCP conduit. Follow-up examinations showed that the structure and functional recovery were improved gradually in the 10-month follow-up; no end-enlargement and any other abnormal reaction associated with the characteristic of neuroma were found. Based on our 33-case studies, we have concluded that PRGD/PDLLA/β-TCP nerve conduit could both promote nerve regeneration and prevent neuroma formation; therefore, it is a good alternative for peripheral nerve repair.

  14. Tumor Necrosis Factor Receptor-associated Factor 6 (TRAF6) Associates with Huntingtin Protein and Promotes Its Atypical Ubiquitination to Enhance Aggregate Formation*

    Science.gov (United States)

    Zucchelli, Silvia; Marcuzzi, Federica; Codrich, Marta; Agostoni, Elena; Vilotti, Sandra; Biagioli, Marta; Pinto, Milena; Carnemolla, Alisia; Santoro, Claudio; Gustincich, Stefano; Persichetti, Francesca

    2011-01-01

    Huntington disease (HD) is a neurodegenerative disorder caused by an expansion of polyglutamines in the first exon of huntingtin (HTT), which confers aggregation-promoting properties to amino-terminal fragments of the protein (N-HTT). Mutant N-HTT aggregates are enriched for ubiquitin and contain ubiquitin E3 ligases, thus suggesting a role for ubiquitination in aggregate formation. Here, we report that tumor necrosis factor receptor-associated factor 6 (TRAF6) binds to WT and polyQ-expanded N-HTT in vitro as well as to endogenous full-length proteins in mouse and human brain in vivo. Endogenous TRAF6 is recruited to cellular inclusions formed by mutant N-HTT. Transient overexpression of TRAF6 promotes WT and mutant N-HTT atypical ubiquitination with Lys6, Lys27, and Lys29 linkage formation. Both interaction and ubiquitination seem to be independent from polyQ length. In cultured cells, TRAF6 enhances mutant N-HTT aggregate formation, whereas it has no effect on WT N-HTT protein localization. Mutant N-HTT inclusions are enriched for ubiquitin staining only when TRAF6 and Lys6, Lys27, and Lys29 ubiquitin mutants are expressed. Finally, we show that TRAF6 is up-regulated in post-mortem brains from HD patients where it is found in the insoluble fraction. These results suggest that TRAF6 atypical ubiquitination warrants investigation in HD pathogenesis. PMID:21454471

  15. Tumor necrosis factor receptor-associated factor 6 (TRAF6) associates with huntingtin protein and promotes its atypical ubiquitination to enhance aggregate formation.

    Science.gov (United States)

    Zucchelli, Silvia; Marcuzzi, Federica; Codrich, Marta; Agostoni, Elena; Vilotti, Sandra; Biagioli, Marta; Pinto, Milena; Carnemolla, Alisia; Santoro, Claudio; Gustincich, Stefano; Persichetti, Francesca

    2011-07-15

    Huntington disease (HD) is a neurodegenerative disorder caused by an expansion of polyglutamines in the first exon of huntingtin (HTT), which confers aggregation-promoting properties to amino-terminal fragments of the protein (N-HTT). Mutant N-HTT aggregates are enriched for ubiquitin and contain ubiquitin E3 ligases, thus suggesting a role for ubiquitination in aggregate formation. Here, we report that tumor necrosis factor receptor-associated factor 6 (TRAF6) binds to WT and polyQ-expanded N-HTT in vitro as well as to endogenous full-length proteins in mouse and human brain in vivo. Endogenous TRAF6 is recruited to cellular inclusions formed by mutant N-HTT. Transient overexpression of TRAF6 promotes WT and mutant N-HTT atypical ubiquitination with Lys(6), Lys(27), and Lys(29) linkage formation. Both interaction and ubiquitination seem to be independent from polyQ length. In cultured cells, TRAF6 enhances mutant N-HTT aggregate formation, whereas it has no effect on WT N-HTT protein localization. Mutant N-HTT inclusions are enriched for ubiquitin staining only when TRAF6 and Lys(6), Lys(27), and Lys(29) ubiquitin mutants are expressed. Finally, we show that TRAF6 is up-regulated in post-mortem brains from HD patients where it is found in the insoluble fraction. These results suggest that TRAF6 atypical ubiquitination warrants investigation in HD pathogenesis.

  16. Promotion and inhibition of flower formation in a dayneutral plant in grafts with a short-day plant and a long-day plant

    Energy Technology Data Exchange (ETDEWEB)

    Lang, A.; Chailakhyan, M.Kh.; Frolova, I.A.

    1977-06-01

    Flower formation in the dayneutral tobacco (Nicotiana tabacum L.) cultivar ''Trapezond'' was accelerated by graft union with the short-day tobacco ''Maryland Mammoth'' when the grafts were kept on short days and by graft union with the long-day plant N. silvestris L. when they were kept on long days. When Maryland Mammoth/Trapezond grafts were kept on long days, flower formation in Trapezond was not, or only slightly, delayed compared to Trapezond/Trapezond controls; but when N. silvestris/Trapezond grafts were kept on short days, flower formation in Trapezond was inhibited and its growth changed to dwarf-like habit. The former results indicate transmission of flower-promoting material(s) (''florigen'') from photoperiodic plants maintained under flower-promoting daylength conditions to a dayneutral graft partner; the latter indicate the presence in the long-day plant N. silvestris under short-day conditions of potent flower-inhibiting and growth-regulating material(s) that can also be transmitted to a day-neutral partner. Analogous flower-inhibitory materials seem not to be present, or to be present to a much lesser extent, in the short-day plant Maryland Mammoth under long-day conditions.

  17. Fe-Al/Al2O3催化臭氧化去除水中有机污染物2,4-D过程中溴酸盐的生成控制研究%Inhibition of bromate formation during catalytic ozonation of organic pollutant 2,4-D in bromide-containing water over Fe-Al/Al2O3

    Institute of Scientific and Technical Information of China (English)

    李能能; 聂玉伦; 胡春

    2013-01-01

    Fe-Al supported on γ-Al2O3 (Fe-Al/Al2O3) was prepared via impregnation method followed by hydrolysis and hydrothermal treatment.Based on characterization of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS),Fe3 + and Fe2 + coexisted-in Fe-Al/Al2O3 while Al was in the state of Al2O3 and AlOOH.In comparison with ozonation alone,the addition of Fe-A1/Al2O3 resulted in complete inhibition of BrO3-formation with higher efficiency for catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D).Moreover,the catalyst could be reused for six times without significant loss of activity,indicating Fe-Al/Al2O3 has an excellent long-term stability.The effects of ozone dose and bromide concentration on TOC removal and bromate formation were also studied.The results showed that no significant bromate formation was found in catalytic ozonation process over FeAl/Al2O3 even with the increased ozone dose and bromide concentration,whereas the increase of ozone dose could result in higher TOC removal efficiency.%采用浸渍、强化水解和后续水浴加热的方法制得催化剂Fe-Al/Al2O3,并通过XRD和XPS等表征手段对其结构性能进行了研究.结果表明,催化剂中铁是以二价和三价存在,且以三价铁为主;铝则以Al2O3和AlOOH形态存在.与单独臭氧化相比,Fe-Al/Al2 O3既能高效矿化水中的难降解有机物2,4-二氯苯氧乙酸(2,4-D),又能明显抑制溴酸盐的生成,体现出很好的循环使用稳定性.进一步探讨了臭氧投加量和溴离子初始浓度对催化臭氧化效率和溴酸盐生成的影响.研究表明,在Fe-Al/Al2O3催化臭氧化过程中,水中溴酸盐浓度受臭氧投加量和溴离子初始浓度的影响较小,均可明显抑制溴酸盐的生成,且有机物的矿化效率随着臭氧投加量的增加而显著提高.

  18. Reductive Cyclodimerization of α,β-Unsaturated Ketones Promoted by AlCl3/Sm System: A Facile Synthesis of 2-Aroyl-1,3,4-triaryl Cyclopentanol Derivatives

    Institute of Scientific and Technical Information of China (English)

    FAN,Xue-Sen; ZHANG,Yong-Min

    2001-01-01

    Promoted by AlCl3/Sm bimetallic system, α, β-unsaturated ketones underwent reductive cyclodimerization to afford cy clopentanol derivatives under mild conditions. The reaction is stereocontrolled and regioselective over the competitive car bon-carbon double bond reduction.

  19. Acetylcholine Protects against Candida albicans Infection by Inhibiting Biofilm Formation and Promoting Hemocyte Function in a Galleria mellonella Infection Model.

    Science.gov (United States)

    Rajendran, Ranjith; Borghi, Elisa; Falleni, Monica; Perdoni, Federica; Tosi, Delfina; Lappin, David F; O'Donnell, Lindsay; Greetham, Darren; Ramage, Gordon; Nile, Christopher

    2015-08-01

    Both neuronal acetylcholine and nonneuronal acetylcholine have been demonstrated to modulate inflammatory responses. Studies investigating the role of acetylcholine in the pathogenesis of bacterial infections have revealed contradictory findings with regard to disease outcome. At present, the role of acetylcholine in the pathogenesis of fungal infections is unknown. Therefore, the aim of this study was to determine whether acetylcholine plays a role in fungal biofilm formation and the pathogenesis of Candida albicans infection. The effect of acetylcholine on C. albicans biofilm formation and metabolism in vitro was assessed using a crystal violet assay and phenotypic microarray analysis. Its effect on the outcome of a C. albicans infection, fungal burden, and biofilm formation were investigated in vivo using a Galleria mellonella infection model. In addition, its effect on modulation of host immunity to C. albicans infection was also determined in vivo using hemocyte counts, cytospin analysis, larval histology, lysozyme assays, hemolytic assays, and real-time PCR. Acetylcholine was shown to have the ability to inhibit C. albicans biofilm formation in vitro and in vivo. In addition, acetylcholine protected G. mellonella larvae from C. albicans infection mortality. The in vivo protection occurred through acetylcholine enhancing the function of hemocytes while at the same time inhibiting C. albicans biofilm formation. Furthermore, acetylcholine also inhibited inflammation-induced damage to internal organs. This is the first demonstration of a role for acetylcholine in protection against fungal infections, in addition to being the first report that this molecule can inhibit C. albicans biofilm formation. Therefore, acetylcholine has the capacity to modulate complex host-fungal interactions and plays a role in dictating the pathogenesis of fungal infections.

  20. Simulation of Cooling Rate Effects on Ti-48Al-2Cr-2Nb Crack Formation in Direct Laser Deposition

    Science.gov (United States)

    Yan, Lei; Li, Wei; Chen, Xueyang; Zhang, Yunlu; Newkirk, Joe; Liou, Frank; Dietrich, David

    2017-03-01

    Transient temperature history is vital in direct laser deposition (DLD) as it reveals the cooling rate at specific temperatures. Cooling rate directly relates to phase transformation and types of microstructure formed in deposits. In this paper, finite element analysis simulation was employed to study the transient temperature history and cooling rate at different experimental setups in the Ti-48Al-2Cr-2Nb DLD process. An innovative prediction strategy was developed to model with a moving Gaussian distribution heat source and element birth and death technology in ANSYS®, and fabricate crack-free deposits. This approach helps to understand and analyze the impact of cooling rate and also explain phase information gathered from x-ray diffraction.

  1. Kinetics of F center annealing and colloid formation in Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kotomin, E.A., E-mail: kotomin@latnet.lv [Institute of Solid State Physics, Kengaraga 8, Riga LV 1063 (Latvia); Kuzovkov, V.N.; Popov, A.I. [Institute of Solid State Physics, Kengaraga 8, Riga LV 1063 (Latvia); Vila, R. [CIEMAT, Madrid (Spain)

    2016-05-01

    The diffusion-controlled kinetics of the F center annealing in Al{sub 2}O{sub 3} (sapphire, corundum) is simulated theoretically for the two regimes: after neutron irradiation when the immobile F centers are annihilated with complementary defects – mobile interstitial oxygen ions, and in thermochemically reduced (additively colored) crystals where mobile F centers aggregate and create the metal colloids. A comparison of the experimental and theoretical kinetics allowed us to estimate the migration energies for the F centers and interstitial oxygen ions. It is obtained that the pre-exponents in diffusion coefficients for defects in different neutron irradiated samples can vary by two orders of magnitude which is attributed by presence of numerous traps for mobile interstitial oxygen ions.

  2. Simulation of Cooling Rate Effects on Ti-48Al-2Cr-2Nb Crack Formation in Direct Laser Deposition

    Science.gov (United States)

    Yan, Lei; Li, Wei; Chen, Xueyang; Zhang, Yunlu; Newkirk, Joe; Liou, Frank; Dietrich, David

    2016-12-01

    Transient temperature history is vital in direct laser deposition (DLD) as it reveals the cooling rate at specific temperatures. Cooling rate directly relates to phase transformation and types of microstructure formed in deposits. In this paper, finite element analysis simulation was employed to study the transient temperature history and cooling rate at different experimental setups in the Ti-48Al-2Cr-2Nb DLD process. An innovative prediction strategy was developed to model with a moving Gaussian distribution heat source and element birth and death technology in ANSYS®, and fabricate crack-free deposits. This approach helps to understand and analyze the impact of cooling rate and also explain phase information gathered from x-ray diffraction.

  3. Effect of Annealing in Magnetic Field on Ferromagnetic Nanoparticle Formation in Cu-Al-Mn Alloy with Induced Martensite Transformation.

    Science.gov (United States)

    Titenko, Anatoliy; Demchenko, Lesya

    2016-12-01

    The paper considers the influence of aging of high-temperature phase on subsequent martensitic transformation in Cu-Al-Mn alloy. The morphology of behavior of martensitic transformation as a result of alloy aging under annealing in a constant magnetic field with different sample orientation relatively to the field direction and without field was studied for direct control of the processes of martensite induction at cooling. Temperature dependences of electrical resistance, magnetic susceptibility, and magnetization, as well as field dependences of magnetization, and phase composition were found. The tendency to the oriented growth of precipitated ferromagnetic phase nanoparticles in a direction of applied field and to an increase of their volume fraction under thermal magnetic treatment of material that favors a reversibility of induced martensitic transformation is observed.

  4. Exchange of interlayer terephthalate anions from a Mg Al layered double hydroxide: formation of intermediate interstratified phases

    Science.gov (United States)

    Kaneyoshi, Masami; Jones, William

    1998-10-01

    The exchange of interlayer terephthalate (TA) anions from a Mg-Al layered double hydroxide (LDH) by carbonate, sulfate, chloride and nitrate anions is reported. It is shown that TA is readily exchanged by CO 32- and SO 42- but only partly by Cl - and NO 3-. We demonstrate that during the exchange process interstratified phases are observed. Such interstratification has previously been reported only for directly synthesised materials. The origin of the interstratification is believed to be associated with two preferred orientations of TA anions within the layers, i.e. vertical or horizontal to the clay sheets. Two models for the possible exchange mechanism which is operating in these systems are proposed.

  5. CH4 reforming with CO2 for syngas production over La2O3 promoted Ni catalysts supported on mesoporous nanostructuredγ-Al2O3

    Institute of Scientific and Technical Information of China (English)

    Narges Habibi; Mehran Rezaei; Nasrollah Majidian; Mahmood Andache

    2014-01-01

    Nanostructuredγ-Al2O3 with high surface area and mesoporous structure was synthesized by sol-gel method and employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by XRD, N2 adsorption-desorption, TPR, TPO, TPH, NH3-TPD and SEM techniques. The BET analysis showed a high surface area of 204 m2·g-1 and a narrow pore-size distribution centered at a diameter of 5.5 nm for catalyst support. The BET results revealed that addition of lanthanum oxide to aluminum oxide decreased the specific surface area. In addition, TPR results showed that addition of lanthanum oxide increased the reducibility of nickel catalyst. The catalytic evaluation results showed an increase in methane conversion with increasing lanthanum oxide to 3 mol%and further increase in lanthanum content decreased the catalytic activity. TPO analysis revealed that the coke deposition decreased with increasing lanthanum oxide to 3 mol%. SEM and TPH analyses confirmed the formation of whisker type carbon over the spent catalysts. Addition of steam and O2 to dry reforming feed increased the methane conversion and led to carbon free operation in combined processes.

  6. Mechanistic insights on iodine(III) promoted metal-free dual C-H activation involved in the formation of a spirocyclic bis-oxindole.

    Science.gov (United States)

    Sreenithya, A; Sunoj, Raghavan B

    2014-12-05

    The mechanism of a metal-free, phenyliodine(III) bis(trifluoroacetate) promoted, dual aryl C-H activation of an anilide to a spirocyclic bis-oxindole is examined using density functional theory (M06-2X). The most preferred pathway proceeds through the involvement of a novel iodonium ion intermediate and a pivotal trifluoroacetate counterion. The two sequential aryl C-H activations, assisted by trifluoroacetate as well as the superior leaving group ability of PhI, facilitate the formation of spirocyclic bis-oxindole.

  7. Au and Al Schottky barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating

    Energy Technology Data Exchange (ETDEWEB)

    Spindt, C.J.; Yamada, M.; Meissner, P.L.; Miyano, K.E.; Herrera, A.; Spicer, W.E. (Stanford Electronics Laboratories, Stanford University, Stanford, California 94305-4055 (US)); Arko, A.J. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (US))

    1991-07-01

    Soft x-ray photoemission spectroscopy has been used to investigate the initial stages of Schottky barrier formation on GaAs (100) surfaces prepared by the thermal desorption of an As cap. This work was motivated by a previous study (Brillson {ital et} {ital al}., J. Vac. Sci. Technol. B {bold 6}, 1263 (1988)) of identically grown and capped samples which reported unpinned'' Schottky barrier formation, with barrier heights falling over a wide range (0.75 eV) of energies. This large energy range is a striking result, as a considerable number of prior studies on both (110) and (100) surfaces have found that all metals will pin in a narrow (0.25 eV) range near midgap. Since Au and Al are the extremes of the larger 0.75 eV span of Schottky barriers, we have studied the deposition of these two metals. We found that the barrier height measurements on the low doped {ital n}-type samples used in this work and in the paper referenced above are affected by photovoltaic effects, even at room temperature. These photovoltaic effects cause shifts in the band bending, which are an artifact of the measurement. We also performed measurements on more heavily doped samples, and the photovoltaic effects were removed. In addition, we point out that Au--Ga alloying makes the case of Au potentially misleading. With the photovoltaic effects removed, and the Au--Ga alloying carefully accounted for, we found that the barriers heights for Au and Al differ by only 0.25 eV.

  8. A Formative Evaluation of Customized Pamphlets to Promote Physical Activity and Symptom Self-Management in Women with Multiple Sclerosis

    Science.gov (United States)

    Plow, Matthew; Bethoux, Francois; Mai, Kimloan; Marcus, Bess

    2014-01-01

    Inactivity is a prevalent problem in the population affected with multiple sclerosis (MS). Thus, there is a need to develop and test physical activity (PA) interventions that can be widely disseminated. We conducted a formative evaluation as part of a randomized controlled trial of a pamphlet-based PA intervention among 30 women with MS. Pamphlets…

  9. Formative Evaluation of MyFit: A Curriculum to Promote Self-Regulation of Physical Activity among Middle School Students

    Science.gov (United States)

    Grim, Melissa; Petosa, Rick; Hortz, Brian; Hunt, Laura

    2013-01-01

    Background: Previous interventions to increase physical activity among middle school students have not produced long-term results. Often, students lack the self-regulation skills needed to support long-term adherence to physical activity. Purpose: The purpose of this study was to conduct a formative evaluation of a self-regulation based physical…

  10. Crucial role of synovial lining macrophages in the promotion of transforming growth factor beta-mediated osteophyte formation.

    NARCIS (Netherlands)

    Lent, P.L.E.M. van; Blom, A.B.; Kraan, P.M. van der; Holthuysen, A.E.M.; Vitters, E.L.; Rooijen, N. van; Smeets, R.L.L.; Nabbe, K.C.A.M.; Berg, W.B. van den

    2004-01-01

    OBJECTIVE: To investigate in vivo and in vitro whether macrophages have an intermediate role in transforming growth factor beta (TGFbeta)-induced osteophyte formation. METHODS: In vivo, synovial lining macrophages were selectively depleted by injection of clodronate-laden liposomes 7 days prior to i

  11. Formative evaluation for promoting adoption of the DGA, 2005 among African American parents and children in the Lower Mississippi Delta

    Science.gov (United States)

    Formative research was conducted to increase adherence to the healthful food and physical activity patterns set forth in the Dietary Guidelines for Americans, 2005 (DGA, 2005) and thereby reduce weight gain and risk factors for obesity-related chronic diseases in African American parents and their c...

  12. 反应热压制备TiC/Al复合材料的形成途径研究%Investigation on Formation Path of TiC/Al Composite Obtained by Reactive Hot-pressing Technology

    Institute of Scientific and Technical Information of China (English)

    宋谋胜; 冉茂武

    2012-01-01

    利用场激发反应热压合成技术研究了Al-Ti-C混合粉末体系制备TiC/Al产物的过程与致密性,并结合DSC实验分析了该体系合成TiC相的形成途径.结果表明,采用反应热压合成法完全能够制备较致密的TiC/Al复合材料.该体系形成TiC相的反应过程为:Ti(s)+3Al(s)=TiAl3(s)→Al(s)=Al(l) →Ti(s)+3 Al(l)=TiAl3(s)→ TiAl3(s)=TiAl3(1)→TiAl3(l)+C(s)=TiC(s)+ Al((l)).混合粉末中的Al不仅作为稀释剂降低体系的反应温度而细化TiC晶粒,还作为反应剂参与了整个反应进程.%Utilizing the field activation reactive hot-pressing (RHP) technology, the process and densificatian of TiC/Al products obtained from Al-Ti-C mixtures system were investigated, eoupied with the DSC experiment to analyze iht formation path of TiC phase in this system. The results show that the dense TiC/Al composite can be fully fabricated by the reactive hot-pressing method. The reaction process of the Al-Ti-C system to form TiC phase can be expressed: Ti(s)+3Al(s)= TiAl3(s) →Al(s)=Al(1)→Ti(,s)+3Al(1)=TiAl,(s)→TiAl3(s)=TiAl3(1)→TiAl3(l)+C(s)=T(C(s)+Al(1). Al in the mixtures plays an important role in serving not only as a diluent to decrease the reaction temperature and thus to refine the TiC grains, but also as an intermediate reactant to participate in the whole reaction process.

  13. Suppression of fibrotic scar formation promotes axonal regeneration without disturbing blood-brain barrier repair and withdrawal of leukocytes after traumatic brain injury.

    Science.gov (United States)

    Yoshioka, Nozomu; Hisanaga, Shin-Ichi; Kawano, Hitoshi

    2010-09-15

    The fibrotic scar containing type IV collagen (Col IV) formed in a lesion site is considered as an obstacle to axonal regeneration, because intracerebral injection of 2,2'-dipyridyl (DPY), an inhibitor of Col IV triple-helix formation, suppresses fibrotic scar formation in the lesion site and promotes axonal regeneration. To determine the role of the fibrotic scar on the healing process of injured central nervous system (CNS), the restoration of blood-brain barrier (BBB) and withdrawal of inflammatory leukocytes were examined in mice subjected to unilateral transection of the nigrostriatal dopaminergic pathway and intracerebral DPY injection. At 5 days after injury, destruction of BBB represented by leakage of Evans blue (EB) and widespread infiltration of CD45-immunoreactive leukocytes was observed around the lesion site, whereas reactive astrocytes increased surrounding the BBB-destroyed area. By 2 weeks after injury, the region of EB leakage and the diffusion of leukocytes were restricted to the inside of the fibrotic scar, and reactive astrocytes gathered around the fibrotic scar. In the DPY-treated lesion site, formation of the fibrotic scar was suppressed (84% decrease in Col IV-deposited area), reactive astrocytes occupied the lesion center, and areas of both EB leakage and leukocyte infiltration decreased by 86%. DPY treatment increased the number of regenerated dopaminergic axons by 2.53-fold. These results indicate that suppression of fibrotic scar formation does not disturb the healing process in damaged CNS, and suggest that this strategy is a reliable tool to promote axonal regeneration after traumatic injury in the CNS.

  14. The mechanism of hot crack formation in Ti-6Al-4V during cold crucible continuous casting

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    Hot crack is one of common defects in castings, which often results in failure of castings. This work studies the formation of hot crack during cold crucible continuous casting by means of experiments and theoretical analysis. The results show that hot crack occurs on the surface and in the circumference of ingots, where the solidified shell and the solidification front meet each other. The tendency of hot cracking decreases with the increase of withdrawal velocities in some extent.The hot crack is caused mainly by the friction force between the shell and the crucible inner wall, and it takes place when the stress resulting from friction exceeds the tensile strength of the shell. The factors of μm, ht, hs and hm, affecting hot cracks are analyzed and verified. In order to decrease the tendency of hot cracks, technical parameters should be optimized by decreasingμm, ht, hs and hm.

  15. Effect of process parameters on properties of Al-Si alloys cast by Rapid Slurry Formation (RSF) technique

    Science.gov (United States)

    Ratke, L.; Sharma, A.; Kohli, D.

    2012-01-01

    Rapid slurry formation is a semi-solid metal forming technique, which is based on a so-called solid enthalpy exchange material (EEM). It is a fascinating technology offering the opportunity to manufacture net-shaped metal components of complex geometry in a single forming operation. At the same time, high mechanical properties can be achieved due to the unique microstructure and flow behaviour. The major process parameters used in the RSF process are rotation speed of the EEM, melt superheat, amount of EEM added (determining fs), and holding time. The process parameters can be well controlled with clear effects on the microstructure. There is a lack of theoretical modelling of the morphological evolution in these two-phase slurries.

  16. Effects of silicate ion concentration on the formation of ceramic oxide layers produced by plasma electrolytic oxidation on Al alloy

    Science.gov (United States)

    Lee, Jung-Hyung; Kim, Seong-Jong

    2017-01-01

    Plasma electrolytic oxidation (PEO) coatings were fabricated on 5083 Al alloy in KOH electrolyte solution with adding various concentrations of Na2SiO3. Changes in voltage-time response and micro-discharge evolution were analyzed, and the surface and cross-section of the resulting coating layer were further characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results showed that discharge characteristics were evidently changed with different Na2SiO3 concentrations, particularly higher Na2SiO3 concentrations leading to lower dielectric breakdown voltages. It was found that porous surface structure became prevalent with increasing Na2SiO3 concentration. The EDS analysis confirmed the incorporation of Si element in the PEO coatings. The result of XRD analysis revealed that metastable phases such as γ- and η-alumina were produced as a result of PEO, while amorphous phases appeared with excessive Na2SiO3 concentrations (10 and 14 g/L). The coating thickness was significantly increased about 2-8 times with increasing Na2SiO3, almost depending on Na2SiO3 concentration.

  17. Integrated Utilization of Sewage Sludge and Coal Gangue for Cement Clinker Products: Promoting Tricalcium Silicate Formation and Trace Elements Immobilization

    Directory of Open Access Journals (Sweden)

    Zhenzhou Yang

    2016-04-01

    Full Text Available The present study firstly proposed a method of integrated utilization of sewage sludge (SS and coal gangue (CG, two waste products, for cement clinker products with the aim of heat recovery and environment protection. The results demonstrated that the incremental amounts of SS and CG addition was favorable for the formation of tricalcium silicate (C3S during the calcinations, but excess amount of SS addition could cause the impediment effect on C3S formation. Furthermore, it was also observed that the C3S polymorphs showed the transition from rhombohedral to monoclinic structure as SS addition was increased to 15 wt %. During the calcinations, most of trace elements could be immobilized especially Zn and cannot be easily leached out. Given the encouraging results in the present study, the co-process of sewage sludge and coal gangue in the cement kiln can be expected with a higher quality of cement products and minimum pollution to the environment.

  18. The Planar Cell Polarity Transmembrane Protein Vangl2 Promotes Dendrite, Spine and Glutamatergic Synapse Formation in the Mammalian Forebrain.

    Science.gov (United States)

    Okerlund, Nathan D; Stanley, Robert E; Cheyette, Benjamin N R

    2016-07-01

    The transmembrane protein Vangl2, a key regulator of the Wnt/planar cell polarity (PCP) pathway, is involved in dendrite arbor elaboration, dendritic spine formation and glutamatergic synapse formation in mammalian central nervous system neurons. Cultured forebrain neurons from Vangl2 knockout mice have simpler dendrite arbors, fewer total spines, less mature spines and fewer glutamatergic synapse inputs on their dendrites than control neurons. Neurons from mice heterozygous for a semidominant Vangl2 mutation have similar but not identical phenotypes, and these phenotypes are also observed in Golgi-stained brain tissue from adult mutant mice. Given increasing evidence linking psychiatric pathophysiology to these subneuronal sites and structures, our findings underscore the relevance of core PCP proteins including Vangl2 to the underlying biology of major mental illnesses and their treatment.

  19. Tumor promoters cause a rapid and reversible inhibition of the formation and maintenance of electrical cell coupling in culture.

    OpenAIRE

    ENOMOTO, T; Sasaki, Y.; Y Shiba; Kanno, Y.; Yamasaki, H

    1981-01-01

    The effect of tumor promoters on electrical coupling between human FL cells was investigated with a microelectrode technique. When a low concentration (100 ng/ml) of 12-O-tetradecanoylphorbol 13-acetate (TPA) was added to culture medium, only 6% of the cells showed electrical coupling after 5 hr, whereas in control medium more than 90% of the cells were coupled. In the presence of TPA, cell coupling remained suppressed for at least another 19 hr. When TPA was washed out from the culture mediu...

  20. Monosodium Urate in the Presence of RANKL Promotes Osteoclast Formation through Activation of c-Jun N-Terminal Kinase

    Directory of Open Access Journals (Sweden)

    Jung-Yoon Choe

    2015-01-01

    Full Text Available The aim of this study was to clarify the role of monosodium urate (MSU crystals in receptor activator of nuclear factor kB ligand- (RANKL- RANK-induced osteoclast formation. RAW 264.7 murine macrophage cells were incubated with MSU crystals or RANKL and differentiated into osteoclast-like cells as confirmed by staining for tartrate-resistant acid phosphatase (TRAP and actin ring, pit formation assay, and TRAP activity assay. MSU crystals in the presence of RANKL augmented osteoclast differentiation, with enhanced mRNA expression of NFATc1, cathepsin K, carbonic anhydrase II, and matrix metalloproteinase-9 (MMP-9, in comparison to RAW 264.7 macrophages incubated in the presence of RANKL alone. Treatment with both MSU crystals and RANKL induced osteoclast differentiation by activating downstream molecules in the RANKL-RANK pathway including tumor necrosis factor receptor-associated factor 6 (TRAF-6, JNK, c-Jun, and NFATc1. IL-1b produced in response to treatment with both MSU and RANKL is involved in osteoclast differentiation in part through the induction of TRAF-6 downstream of the IL-1b pathway. This study revealed that MSU crystals contribute to enhanced osteoclast formation through activation of RANKL-mediated pathways and recruitment of IL-1b. These findings suggest that MSU crystals might be a pathologic causative agent of bone destruction in gout.

  1. Nudel is crucial for the WAVE complex assembly in vivo by selectively promoting subcomplex stability and formation through direct interactions

    Institute of Scientific and Technical Information of China (English)

    Shuang Wu; Li Ma; Yibo Wu; Rong Zeng; Xueliang Zhu

    2012-01-01

    The WAVE regulatory complex (WRC),consisting of WAVE,Sra,Nap,Abi,and HSPC300,activates the Arp2/3 complex to control branched actin polymerization in response to Rac activation.How the WRC is assembled in vivo is not clear.Here we show that Nudel,a protein critical for lamellipodia formation,dramatically stabilized the Sra1-Nap1-Abi1 complex against degradation in cells through a dynamic binding to Sra1,whereas its physical interaction with HSPC300 protected free HSPC300 from the proteasome-mediated degradation and stimulated the HSPC300-WAVE2 complex formation.By contrast,Nudel showed little or no interactions with the Sra1-Nap1-Abi1-WAVE2 and the Sra1-Nap1-Abi1-HSPC300 complexes as well as the mature WRC.Depletion of Nudel by RNAi led to general subunit degradation and markedly attenuated the levels of mature WRC.It also abolished the WRC-dependent actin polymerization in vitro and the Rac1-induced lamellipodial actin network formation during cell spreading.Therefore,Nudel is important for the early steps of the WRC assembly in vivo by antagonizing the instability of certain WRC subunits and subcomplexes.

  2. Capsicum annuum S (CaS) promotes reproductive transition and is required for flower formation in pepper (Capsicum annuum).

    Science.gov (United States)

    Cohen, Oded; Borovsky, Yelena; David-Schwartz, Rakefet; Paran, Ilan

    2014-05-01

    The genetic control of the transition to flowering has mainly been studied in model species, while few data are available in crop species such as pepper (Capsicum spp.). To elucidate the genetic control of the transition to flowering in pepper, mutants that lack flowers were isolated and characterized. Genetic mapping and sequencing allowed the identification of the gene disrupted in the mutants. Double mutants and expression analyses were used to characterize the relationships between the mutated gene and other genes controlling the transition to flowering and flower differentiation. The mutants were characterized by a delay in the initiation of sympodial growth, a delay in the termination of sympodial meristems and complete inhibition of flower formation. Capsicum annuum S (CaS), the pepper (Capsicum annuum) ortholog of tomato (Solanum lycopersicum) COMPOUND INFLORESCENCE and petunia (Petunia hybrida) EVERGREEN, was found to govern the mutant phenotype. CaS is required for the activity of the flower meristem identity gene Ca-ANANTHA and does not affect the expression of CaLEAFY. CaS is epistatic over other genes controlling the transition to flowering with respect to flower formation. Comparative homologous mutants in the Solanaceae indicate that CaS has uniquely evolved to have a critical role in flower formation, while its role in meristem maturation is conserved in pepper, tomato and petunia.

  3. saeRS and sarA act synergistically to repress protease production and promote biofilm formation in Staphylococcus aureus.

    Directory of Open Access Journals (Sweden)

    Lara N Mrak

    Full Text Available Mutation of the staphylococcal accessory regulator (sarA limits biofilm formation in diverse strains of Staphylococcus aureus, but there are exceptions. One of these is the commonly studied strain Newman. This strain has two defects of potential relevance, the first being mutations that preclude anchoring of the fibronectin-binding proteins FnbA and FnbB to the cell wall, and the second being a point mutation in saeS that results in constitutive activation of the saePQRS regulatory system. We repaired these defects to determine whether either plays a role in biofilm formation and, if so, whether this could account for the reduced impact of sarA in Newman. Restoration of surface-anchored FnbA enhanced biofilm formation, but mutation of sarA in this fnbA-positive strain increased rather than decreased biofilm formation. Mutation of sarA in an saeS-repaired derivative of Newman (P18L or a Newman saeRS mutant (ΔsaeRS resulted in a biofilm-deficient phenotype like that observed in clinical isolates, even in the absence of surface-anchored FnbA. These phenotypes were correlated with increased production of extracellular proteases and decreased accumulation of FnbA and/or Spa in the P18L and ΔsaeRS sarA mutants by comparison to the Newman sarA mutant. The reduced accumulation of Spa was reversed by mutation of the gene encoding aureolysin, while the reduced accumulation of FnbA was reversed by mutation of the sspABC operon. These results demonstrate that saeRS and sarA act synergistically to repress the production of extracellular proteases that would otherwise limit accumulation of critical proteins that contribute to biofilm formation, with constitutive activation of saeRS limiting protease production, even in a sarA mutant, to a degree that can be correlated with increased enhanced capacity to form a biofilm. Although it remains unclear whether these effects are mediated directly or indirectly, studies done with an sspA::lux reporter suggest they

  4. Suppression of carbon formation in CH4–CO2 reforming by addition of Sr into bimetallic Ni–Co/γ-Al2O3 catalyst

    Directory of Open Access Journals (Sweden)

    Ahmed Al-Fatesh

    2015-01-01

    Full Text Available Bimetallic catalysts, containing 5 wt% Ni + 5 wt% Co supported on γ-Al2O3 combined with different amounts of Sr promoter ranging from 0 to 1 wt%, for dry reforming reaction were prepared by the impregnation method. The dry reforming reaction was carried out at atmospheric pressure using CO2/CH4/N2 feed ratio of 17/17/2, F/W = 60 mL/min gcat and reaction temperature range of 500–700 °C. The performance of the developed catalyst was evaluated by estimating the CH4 and CO2 conversions, and by performing a long run stability test. The fresh and spent catalysts were characterized by BET, TGA, TPD, TPR, and TPO. The bimetallic catalysts provided higher activity than the monometallic-catalysts. When the bimetallic was promoted with Sr, the activity decreased slightly however, the stability enhanced. The best stability, estimated by the deactivation factor, and less carbon deposition, measured by TGA, were obtained when 5Ni5CoSr0.75 catalyst was used.

  5. Interaction of aluminum projectiles with quartz sand in impact experiments: Formation of khatyrkite (CuAl2) and reduction of SiO2 to Si

    Science.gov (United States)

    Hamann, Christopher; Stöffler, Dieter; Reimold, Wolf Uwe

    2016-11-01

    We analyzed the interaction of spherical, 6.36-mm-diameter, Cu-bearing aluminum projectiles with quartz sand targets in hypervelocity impact experiments performed at NASA Ames Vertical Gun Range. Impact velocities and inferred peak shock pressures varied between 5.9 and 6.5 km/s and ∼41 and 48 GPa, respectively. Shocked particles ("impact melt particles") coated with thin crusts of molten projectile material were recovered from the floors of the ca. 33-cm-diameter craters and the respective ejecta blankets. Through petrographic and chemical (optical microscopy, FE-EMPA, SEM-EDX, and XRF) analysis we show that these particles have a layered structure manifested in distinct layers of decreasing shock metamorphism. These can be characterized by the following physical and chemical reactions and alteration products: (i) complete melting and subsequent recrystallization of the projectile, forming a distinct crystallization texture in the fused metal crust; (ii) projectile-target mixing, involving a redox reaction between Cu-bearing Al alloy und SiO2, leading to formation of khatyrkite (CuAl2), Al2O3 melt, euhedral silicon crystals, and spherical droplets of silicon; (iii) melting of quartz to lechatelierite and formation of planar deformation features in relic quartz grains; and (iv) shock lithification of quartz grains with fracturing of grains, grain-boundary melting, planar deformation features, and complete loss of porosity. To our knowledge, this is the first report of khatyrkite formed experimentally in hypervelocity impact experiments. These results have implications for the understanding of a similar redox reaction between Al-Cu metal and siliceous impact melt recently postulated for the Khatyrka CV3 carbonaceous chondrite. Moreover, these results bear on the processes that lead to layers of regolith on the surfaces of planetary bodies without atmospheres, such as asteroids in the main belt (e.g., 4 Vesta), and on the Moon. Specifically, impacts of mm

  6. Elevated AKR1C3 expression promotes prostate cancer cell survival and prostate cell-mediated endothelial cell tube formation: implications for prostate cancer progressioan

    Directory of Open Access Journals (Sweden)

    Davis Jeffrey S

    2010-12-01

    Full Text Available Abstract Background Aldo-keto reductase (AKR 1C family member 3 (AKR1C3, one of four identified human AKR1C enzymes, catalyzes steroid, prostaglandin, and xenobiotic metabolism. In the prostate, AKR1C3 is up-regulated in localized and advanced prostate adenocarcinoma, and is associated with prostate cancer (PCa aggressiveness. Here we propose a novel pathological function of AKR1C3 in tumor angiogenesis and its potential role in promoting PCa progression. Methods To recapitulate elevated AKR1C3 expression in cancerous prostate, the human PCa PC-3 cell line was stably transfected with an AKR1C3 expression construct to establish PC3-AKR1C3 transfectants. Microarray and bioinformatics analysis were performed to identify AKR1C3-mediated pathways of activation and their potential biological consequences in PC-3 cells. Western blot analysis, reverse transcription-polymerase chain reaction (RT-PCR, enzyme-linked immunosorbent assay (ELISA, and an in vitro Matrigel angiogenesis assays were applied to validate the pro-angiogenic activity of PC3-AKR1C3 transfectants identified by bioinformatics analysis. Results Microarray and bioinformatics analysis suggested that overexpression of AKR1C3 in PC-3 cells modulates estrogen and androgen metabolism, activates insulin-like growth factor (IGF-1 and Akt signaling pathways, as well as promotes tumor angiogenesis and aggressiveness. Levels of IGF-1 receptor (IGF-1R and Akt activation as well as vascular endothelial growth factor (VEGF expression and secretion were significantly elevated in PC3-AKR1C3 transfectants in comparison to PC3-mock transfectants. PC3-AKR1C3 transfectants also promoted endothelial cell (EC tube formation on Matrigel as compared to the AKR1C3-negative parental PC-3 cells and PC3-mock transfectants. Pre-treatment of PC3-AKR1C3 transfectants with a selective IGF-1R kinase inhibitor (AG1024 or a non-selective phosphoinositide 3-kinases (PI3K inhibitor (LY294002 abolished ability of the cells

  7. Murid Gammaherpesvirus Latency-Associated Protein M2 Promotes the Formation of Conjugates between Transformed B Lymphoma Cells and T Helper Cells.

    Directory of Open Access Journals (Sweden)

    Diana Fontinha

    Full Text Available Establishment of persistent infection in memory B cells by murid herpesvirus-4 (MuHV-4 depends on the proliferation of latently infected germinal center B cells, for which T cell help is essential. Whether the virus is capable of modulating B-T helper cell interaction for its own benefit is still unknown. Here, we investigate if the MuHV-4 latency associated M2 protein, which assembles multiprotein complexes with B cell signaling proteins, plays a role. We observed that M2 led to the upregulation of adhesion and co-stimulatory molecules in transduced B cell lines. In an MHC-II restricted OVA peptide-specific system, M2 polarized to the B-T helper contact zone. Furthermore, it promoted B cell polarization, as demonstrated by the increased proximity of the B cell microtubule organizing center to the interface. Consistent with these data, M2 promoted the formation of B-T helper cell conjugates. In an in vitro competition assay, this translated into a competitive advantage, as T cells preferentially conjugated with M2-expressing B cells. However, expression of M2 alone in B cells was not sufficient to lead to T cell activation, as it only occurred in the presence of specific peptide. Taken together, these findings support that M2 promotes the formation of B-T helper cell conjugates. In an in vivo context this may confer a competitive advantage to the infected B cell in acquisition of T cell help and initiation of a germinal center reaction, hence host colonization.

  8. Insights on co-catalyst-promoted enamine formation between dimethylamine and propanal through ab initio and density functional theory study.

    Science.gov (United States)

    Patil, Mahendra P; Sunoj, Raghavan B

    2007-10-26

    The mechanistic details on enamine formation between dimethylamine and propanal are unraveled using the ab initio and density functional theory methods. The addition of secondary amine to the electrophile and simultaneous proton transfer results in a carbinolamine intermediate, which subsequently undergoes dehydration to form enamine. The direct addition of amine as well as the dehydration of the resulting carbinolamine intermediate is predicted to possess fairly high activation barrier implying that a unimolecular process is unlikely to be responsible for enamine formation. Different models are therefore proposed which could explain the relative ease of enamine formation under neat condition as well as under the influence of methanol as the co-catalyst. The explicit inclusion of either the reagent or the co-catalyst is considered in the transition states as stabilizing agents. The participation of the reagent or the co-catalyst as a monofunctional ancillary species is found to stabilize the transition states relative to the unassisted or the direct addition/dehydration pathways. The reduction in enthalpy of activation is found to be much more dramatic when two co-catalysts participate in an active bifunctional mode in the rate-determining dehydration step. The transition structures exhibited characteristic features of a relay proton transfer mechanism. The free energy of activation associated with the two methanol-assisted pathway is found to be 16.7 kcal/mol lower than that of the unassisted pathway. The results are found to be in concurrence with the available reports on the rate acceleration by co-catalysts in the Michael reaction between enamine and methyl vinyl ketone under neat conditions.

  9. A synthetic peptide from the COOH-terminal heparin-binding domain of fibronectin promotes focal adhesion formation

    DEFF Research Database (Denmark)

    Woods, A; McCarthy, J B; Furcht, L T;

    1993-01-01

    of focal adhesion and stress fiber formation requires additional interactions. Heparin-binding fragments of fibronectin can provide this signal. The COOH-terminal heparin-binding domain of fibronectin contains five separate heparin-binding amino acid sequences. We show here that all five sequences...... PRARI. The biological response to this peptide and to the COOH-terminal fragment may be mediated through cell surface heparan sulfate proteoglycans because treatment of cells with heparinase II and III, or competition with heparin, reduces the response. Treatment with chondroitinase ABC or competition...

  10. BMP4 promotes formation of primitive vascular networks in human embryonic stem cell-derived embryoid bodies.

    Science.gov (United States)

    Boyd, N L; Dhara, S K; Rekaya, R; Godbey, E A; Hasneen, K; Rao, R R; West, F D; Gerwe, B A; Stice, S L

    2007-06-01

    The vasculature develops primarily through two processes, vasculogenesis and angiogenesis. Although much work has been published on angiogenesis, less is known of the mechanisms regulating the de novo formation of the vasculature commonly called vasculogenesis. Human embryonic stem cells (hESC) have the capability to produce all of the cells of the body and have been used as in vitro models to study the molecular signals controlling differentiation and vessel assembly. One such regulatory molecule is bone morphogenetic protein-4 (BMP4), which is required for mesoderm formation and vascular/hematopoietic specification in several species. However, hESC grown in feeder-free conditions and treated with BMP4 differentiate into a cellular phenotype highly expressing a trophoblast gene profile. Therefore, it is unclear what role, if any, BMP4 plays in regulating vascular development in hESC. Here we show in two National Institutes of Health-registered hESC lines (BG02 and WA09) cultured on a 3D substrate of Matrigel in endothelial cell growth medium-2 that the addition of BMP4 (100 ng/ml) for 3 days significantly increases the formation and outgrowth of a network of cells reminiscent of capillary-like structures formed by mature endothelial cells (P<0.05). Analysis of the expression of 45 genes by quantitative real time-polymerase chain reaction on a low-density array of the entire culture indicates a rapid and significant downregulation of pluripotent and most ectodermal markers with a general upregulation of endoderm, mesoderm, and endothelial markers. Of the genes assayed, BMPR2 and RUNX1 were differentially affected by exposure to BMP4 in both cell lines. Immunocytochemistry indicates the morphological structures formed were negative for the mature endothelial markers CD31 and CD146 as well as the neural marker SOX2, yet positive for the early vascular markers of endothelium (KDR, NESTIN) and smooth muscle cells (alpha-smooth muscle actin [alpha SMA]). Together, these

  11. Synergistic effects of high dietary calcium and exogenous parathyroid hormone in promoting osteoblastic bone formation in mice

    OpenAIRE

    Feng, Yuxu; Zhou, Min; Zhang, Qunhu; Liu, Huan; Xu, Yong; Shu, Lei; Zhang, Jue; Miao, Dengshun; Ren, Yongxin

    2015-01-01

    In the present study, we investigated whether high dietary Ca and exogenous parathyroid hormone 1–34 fragments (PTH 1–34) have synergistic effects on bone formation in adult mice, and explored the related mechanisms. Adult male mice were fed a normal diet, a high-Ca diet, a PTH-treated diet, or a high-Ca diet combined with subcutaneously injected PTH 1–34 (80 μg/kg per d) for 4 weeks. Bone mineral density, trabecular bone volume, osteoblast number, alkaline phosphatase (ALP)- and type I colla...

  12. Evidence of spring formation and subrosion-induced sinkhole development at Ghor Al-Haditha, Jordan, from repeated close-range photogrammetry

    Science.gov (United States)

    Al-Halbouni, Djamil; Eoghan, P. Holohan; Leila, Saberi; Hussam, Alrshdan; Thomas, Walter; Ali, Sawarieh; Torsten, Dahm

    2016-04-01

    The widespread development of sinkholes and land subsidence poses a major geological hazard to infrastructure, local population, agriculture and industry in the Dead Sea area. For assessment of the key physical factors in this development, repeated photogrammetric and field surveys at Ghor Al-Haditha in Jordan have been undertaken. Recent results provide evidence for subrosion based on strong periodic water flows, as the basic underlying physical process of such land subsidence phenomena. From combined Helikite- and Quatrocopter-based photogrammetric surveys, high resolution Digital Surface Models from October 2014 and October 2015 are compared. Change detection reveals: (1) active subsidence in a hundred metre-scale depression zone, (2) a highly-dynamic spring and canyon system connected with recent sinkhole collapses and (3) the rapid formation of new sinkholes both in alluvium and mud cover sediments. The formation of new sinkholes has been documented locally by means of aerial and field observations during a storm with strong rainfall. A new artesian spring formed in the former Dead Sea bed (mud-flat) at this event. The alluvial sediment load of the stream, a periodic location change of the spring and a connected uphill sinkhole cluster formation provide strong evidence for subrosion of weak material with subsequent underground void collapse. Additionally a documented lake and its' subsequent drainage forming a new canyon reveals the local penetration of the aquiclude behavior of the mud-flat in the major depression area, which can be explained by an under-saturated groundwater flow at a strong hydrostatic gradient. Furthermore an enlargement of the investigated area in the 2015 survey indicates a continuation of subsidence and sinkhole activity towards the North. It reveals several points of emanation of water streams in the mud-flat beneath the alluvial cover and vegetation as an indicator of relatively fresh groundwater inflow. This repeated photogrammetry

  13. FGFR3 promotes angiogenesis-dependent metastasis of hepatocellular carcinoma via facilitating MCP-1-mediated vascular formation.

    Science.gov (United States)

    Liu, Xinyu; Jing, Xiaoqian; Cheng, Xi; Ma, Ding; Jin, Zhijian; Yang, Weiping; Qiu, Weihua

    2016-05-01

    The biological role of fibroblast growth factor receptor 3 (FGFR3) in tumor angiogenesis of hepatocellular carcinoma (HCC) has not been discussed before. Our previous work had indicated FGFR3 was overexpressed in HCC, and silencing FGFR3 in Hu7 cells could regulate tumorigenesis via down-regulating the phosphorylation level of key members of classic signaling pathways including ERK and AKT. In the present work, we explored the role of FGFR3 in angiogenesis-dependent metastasis by using SMMC-7721 and QGY-7703 stable cell lines. Our results indicated FGFR3 could regulate in vitro cell migration ability and in vivo lung metastasis ability of HCC, which was in accordance with increased angiogenesis ability in vitro and in vivo. Using the supernatant from SMMC-7721/FGFR3 cells, we conducted a human angiogenesis protein microarray including 43 angiogenesis factors and found that FGFR3 modulated angiogenesis and metastasis of HCC mainly by promoting the protein level of monocyte chemotactic protein 1 (MCP-1). Silencing FGFR3 by short hairpin RNA (shRNA) could reduce MCP-1 level in lysates and supernatant of QGY-7703 cells and SMMC-7721 cells. Silencing MCP-1 in QGY-7703 or SMMC-7721 cells could induce similar phenotypes compared with silencing FGFR3. Our results suggested FGFR3 promoted metastasis potential of HCC, at least partially if not all, via facilitating MCP-1-mediated angiogenesis, in addition to previously found cell growth and metastasis. MCP-1, a key medium between HCC cells and HUVECs, might be a novel anti-vascular target in HCC.

  14. Formation of copper nanoparticles in mordenite s with variable SiO{sub 2}/Al{sub 2}O{sub 3} molar ratios under redox treatments

    Energy Technology Data Exchange (ETDEWEB)

    Petranovskii, V.; Avalos, M. [UNAM, Centro de Nanociencias y Nanotecnologia, Km 107 Carretera Tijuana-Ensenada, 22800 Ensenada, Baja California (Mexico); Stoyanov, E. [University of California, Department of Chemistry, Riverside, 92521 California (United States); Gurin, V. [Belarusian State University, Research Institute for Physical Chemical Problems, Minsk 220080 (Belarus); Katada, N. [Tottori University, Department of Chemistry and Biotechnology, Tottori 680-8552 (Japan); Hernandez, M. A. [Benemerita Universidad Autonoma de Puebla, Departamento de Investigacion en Zeolitas, Ciudad Universitaria, Puebla (Mexico); Pestryakov, A. [Tomsk Polytechnic University, Tomsk 634050 (Russian Federation); Chavez R, F.; Zamorano U, R. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Fisica, Zacatenco, 07738 Mexico D. F. (Mexico); Portillo, R., E-mail: vitalii@cnyn.unam.mx [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Quimicas, Ciudad Universitaria, Puebla (Mexico)

    2013-05-01

    A series of protonated copper-containing mordenite s with different SiO{sub 2}/Al{sub 2}O{sub 3} molar ratios (MR) in the range of 10{<=}MR{<=}206 was prepared by ion exchange in copper nitrate aqueous solution. The electron paramagnetic resonance of hydrated copper Mordenite s series testifies of several Cu{sup 2+} ion sites. Hydrogen reduction of copper ions incorporated into the mordenite s was shown to lead to different reduced copper species including small metallic particles inter alia. The structural properties and acidity of mordenite s were characterized. The optical appearance of the copper particles showed strong but nonmonotonic dependence on the MR value, in line with the variation in acidity of this series of mordenite s. Correlations between mordenite properties and the formation of different reduced copper species are discussed. (Author)

  15. Phase-field simulation of formation of cellular dendrites and fine cellular structures at high growth velocities during directional solidification of Ti56Al44 alloy

    Institute of Scientific and Technical Information of China (English)

    LI Xin-zhong; GUO Jing-jie; SU Yan-qing; WU Shi-ping; FU Heng-zhi

    2005-01-01

    A phase-field model whose free energy of the solidification system derived from the Calphad thermodynamic modeling of phase diagram was used to simulate formation of cellular dendrites and fine cellular structures of Ti56Al44 alloy during directional solidification at high growth velocities. The liquid-solid phase transition of L→β was chosen. The dynamics of breakdown of initially planar interfaces into cellular dendrites and fine cellular structures were shown firstly at two growth velocities. Then the unidirectional free growths of two initial nucleations evolving to fine cellular dendrites were investigated. The tip splitting phenomenon is observed and the negative temperature gradient in the liquid represents its supercooling directional solidification. The simulation results show the realistic evolution of interfaces and microstructures and they agree with experimental one.

  16. Formation of Sn-M (M=Fe, Al, Ni) alloy nanoparticles by DC arc-discharge and their electrochemical properties as anodes for Li-ion batteries

    Science.gov (United States)

    Gao, Song; Huang, Hao; Wu, Aimin; Yu, Jieyi; Gao, Jian; Dong, Xinglong; Liu, Chunjing; Cao, Guozhong

    2016-10-01

    A direct current arc-discharge method was applied to prepare the Sn-M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn-M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn-Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g-1/366.6 mA h g-1) and optimal cycle stability (a specific reversible capacity of 240 mA h g-1 maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process.

  17. Si{sub 3}N{sub 4} whisker upper layer formation on a SiC-Al{sub 2}O{sub 3} porous body

    Energy Technology Data Exchange (ETDEWEB)

    Toro, P.; Perez, A.; Baeza, G. [Univ. de Chile, Santiago (Chile). Dept. Quimica Basica; Piderit, G.; Rojas, P. [Comision Chilena de Energia Nuclear, Santiago (Chile)

    1996-12-31

    A thin upper layer on a SiC-Al{sub 2}O{sub 3} porous substrate was formed by spray deposition of a Si-C composite or SiC fine powder 55.0 wt% total powder suspension. The formation of a compact layer of Si{sub 3}N{sub 4} whisker or a SiC smaller pore size than the porous substrate was obtained under thermal treatment up to 1,400 C for 3--4 h in a nitrogen or argon gas environment, respectively. SEM microstructure observations and a qualitative (DRX-EDAX) analysis of both sintered porous bodies were performed to confirm the nature of both layers.

  18. Promoting oxygen vacancy formation and p-type conductivity in SrTiO3via alkali metal doping: a first principles study.

    Science.gov (United States)

    Triggiani, Leonardo; Muñoz-García, Ana B; Agostiano, Angela; Pavone, Michele

    2016-10-19

    Strontium titanate (SrTiO3, STO) is a prototypical perovskite oxide, widely exploited in many technological applications, from catalysis to energy conversion devices. In the context of solid-oxide fuel cells, STO has been recently applied as an epitaxial substrate for nano-sized layers of mixed ion-electron conductive catalysts with enhanced electrochemical performances. To extend the applications of such heterogeneous nano-cathodes in real devices, also the STO support should be active for both electron transport and oxide diffusion. To this end, we explored using first-principles calculations the strategy of doping of STO at the Sr site with sodium and potassium. These two ions fit in the perovskite structure and induce holes in the STO valence band, so as to obtain the desired p-type electronic conduction. At the same time, the doping with alkali ions also promotes the formation of oxygen vacancies in STO, a prerequisite for effective oxide diffusion. Analysis of electron density rearrangements upon defect formation allows relating the favorable vacancy formation energies to an improved electronic delocalization over the oxide sub-lattice, as observed in closely related materials (e.g. Sr2Fe1.5Mo0.5O6). Overall, our results suggest the alkali-doped STO as a new potential substrate material in nanoscale heterogeneous electrodes for solid oxide electrochemical cells.

  19. Is active management the key to the conservation of saproxylic biodiversity? Pollarding promotes the formation of tree hollows.

    Directory of Open Access Journals (Sweden)

    Pavel Sebek

    Full Text Available Trees with hollows are key features sustaining biodiversity in wooded landscapes. They host rich assemblages of often highly specialised organisms. Hollow trees, however, have become rare and localised in Europe. Many of the associated biota is thus declining or endangered. The challenge of its conservation, therefore, is to safeguard the presence of hollow trees in sufficient numbers. Populations of numerous species associated with tree hollows and dead wood are often found in habitats that were formed by formerly common traditional silvicultural practices such as coppicing, pollarding or pasture. Although it has been occasionally mentioned that such practices increase the formation of hollows and the availability of often sun-exposed dead wood, their effect has never been quantified. Our study examined the hollow incidence in pollard and non-pollard (unmanaged willows and the effect of pollarding on incremental growth rate by tree ring analysis. The probability of hollow occurrence was substantially higher in pollard than in non-pollard trees. Young pollards, especially, form hollows much more often than non-pollards; for instance, in trees of 50 cm DBH, the probability of hollow ocurrence was ∼0.75 in pollards, but only ∼0.3 in non-pollards. No difference in growth rate was found. Pollarding thus leads to the rapid formation of tree hollows, a habitat usually associated with old trees. It is therefore potentially a very important tool in the restoration of saproxylic habitats and conservation of hollow-dependent fauna. If applied along e.g. roads and watercourses, pollarding could also be used to increase landscape connectivity for saproxylic organisms. In reserves where pollarding was formerly practiced, its restoration would be necessary to prevent loss of saproxylic biodiversity. Our results point to the importance of active management measures for maintaining availability, and spatial and temporal continuity of deadwood microhabitats.

  20. Extracorporeal shock waves alone or combined with raloxifene promote bone formation and suppress resorption in ovariectomized rats

    Science.gov (United States)

    Corrado, Bruno; Pirozzi, Claudio; Paciello, Orlando; Pagano, Teresa Bruna; Russo, Sergio; Calignano, Antonio; Mattace Raso, Giuseppina; Meli, Rosaria

    2017-01-01

    Osteoporosis is a metabolic skeletal disease characterized by an imbalance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation. We examined the beneficial effect of shock waves (SW) alone or in combination with raloxifene (RAL) on bone loss in ovariectomized rats (OVX). Sixteen weeks after surgery, OVX were treated for five weeks with SW at the antero-lateral side of the right hind leg, one session weekly, at 3 Hz (EFD of 0.33 mJ/mm2), or with RAL (5 mg/kg/die, per os) or with SW+RAL. Sera, femurs, tibiae and vertebrae were sampled for following biochemical and histological analysis. SW, alone or combined with RAL, prevented femur weight reduction and the deterioration of trabecular microarchitecture both in femur and vertebrae. All treatments increased Speed of Sound (SoS) values, improving bone mineral density, altered by OVX. Serum parameters involved in bone remodeling (alkaline phosphatase, receptor activator of nuclear factor kappa-B ligand, osteoprotegerin) and osteoblast proliferation (PTH), altered by ovariectomy, were restored by SW and RAL alone or in combination. In tibiae, SW+RAL significantly reduced cathepsin k and TNF-α levels, indicating the inhibition of osteoclast activity, while all treatments significantly increased runt-related transcription factor 2 and bone morphogenetic-2 expression, suggesting an increase in osteoblastogenic activity. Finally, in bone marrow from tibiae, SW or RAL reduced PPARγ and adiponectin transcription, indicating a shift of mesenchymal cells toward osteoblastogenesis, without showing a synergistic effect. Our data indicate SW therapy, alone and in combination with raloxifene, as an innovative strategy to limit the hypoestrogenic bone loss, restoring the balance between bone formation and resorption. PMID:28158228

  1. Progesterone promotes focal adhesion formation and migration in breast cancer cells through induction of protease-activated receptor-1.

    Science.gov (United States)

    Diaz, Jorge; Aranda, Evelyn; Henriquez, Soledad; Quezada, Marisol; Espinoza, Estefanía; Bravo, Maria Loreto; Oliva, Bárbara; Lange, Soledad; Villalon, Manuel; Jones, Marius; Brosens, Jan J; Kato, Sumie; Cuello, Mauricio A; Knutson, Todd P; Lange, Carol A; Leyton, Lisette; Owen, Gareth I

    2012-08-01

    Progesterone and progestins have been demonstrated to enhance breast cancer cell migration, although the mechanisms are still not fully understood. The protease-activated receptors (PARs) are a family of membrane receptors that are activated by serine proteases in the blood coagulation cascade. PAR1 (F2R) has been reported to be involved in cancer cell migration and overexpressed in breast cancer. We herein demonstrate that PAR1 mRNA and protein are upregulated by progesterone treatment of the breast cancer cell lines ZR-75 and T47D. This regulation is dependent on the progesterone receptor (PR) but does not require PR phosphorylation at serine 294 or the PR proline-rich region mPRO. The increase in PAR1 mRNA was transient, being present at 3  h and returning to basal levels at 18  h. The addition of a PAR1-activating peptide (aPAR1) to cells treated with progesterone resulted in an increase in focal adhesion (FA) formation as measured by the cellular levels of phosphorylated FA kinase. The combined but not individual treatment of progesterone and aPAR1 also markedly increased stress fiber formation and the migratory capacity of breast cancer cells. In agreement with in vitro findings, data mining from the Oncomine platform revealed that PAR1 expression was significantly upregulated in PR-positive breast tumors. Our observation that PAR1 expression and signal transduction are modulated by progesterone provides new insight into how the progestin component in hormone therapies increases the risk of breast cancer in postmenopausal women.

  2. Is active management the key to the conservation of saproxylic biodiversity? Pollarding promotes the formation of tree hollows.

    Science.gov (United States)

    Sebek, Pavel; Altman, Jan; Platek, Michal; Cizek, Lukas

    2013-01-01

    Trees with hollows are key features sustaining biodiversity in wooded landscapes. They host rich assemblages of often highly specialised organisms. Hollow trees, however, have become rare and localised in Europe. Many of the associated biota is thus declining or endangered. The challenge of its conservation, therefore, is to safeguard the presence of hollow trees in sufficient numbers. Populations of numerous species associated with tree hollows and dead wood are often found in habitats that were formed by formerly common traditional silvicultural practices such as coppicing, pollarding or pasture. Although it has been occasionally mentioned that such practices increase the formation of hollows and the availability of often sun-exposed dead wood, their effect has never been quantified. Our study examined the hollow incidence in pollard and non-pollard (unmanaged) willows and the effect of pollarding on incremental growth rate by tree ring analysis. The probability of hollow occurrence was substantially higher in pollard than in non-pollard trees. Young pollards, especially, form hollows much more often than non-pollards; for instance, in trees of 50 cm DBH, the probability of hollow ocurrence was ∼0.75 in pollards, but only ∼0.3 in non-pollards. No difference in growth rate was found. Pollarding thus leads to the rapid formation of tree hollows, a habitat usually associated with old trees. It is therefore potentially a very important tool in the restoration of saproxylic habitats and conservation of hollow-dependent fauna. If applied along e.g. roads and watercourses, pollarding could also be used to increase landscape connectivity for saproxylic organisms. In reserves where pollarding was formerly practiced, its restoration would be necessary to prevent loss of saproxylic biodiversity. Our results point to the importance of active management measures for maintaining availability, and spatial and temporal continuity of deadwood microhabitats.

  3. TGF-β induces p53/Smads complex formation in the PAI-1 promoter to activate transcription

    Science.gov (United States)

    Kawarada, Yuki; Inoue, Yasumichi; Kawasaki, Fumihiro; Fukuura, Keishi; Sato, Koichi; Tanaka, Takahito; Itoh, Yuka; Hayashi, Hidetoshi

    2016-01-01

    Transforming growth factor β (TGF-β) signaling facilitates tumor development during the advanced stages of tumorigenesis, but induces cell-cycle arrest for tumor suppression during the early stages. However, the mechanism of functional switching of TGF-β is still unknown, and it is unclear whether inhibition of TGF-β signaling results amelioration or exacerbation of cancers. Here we show that the tumor suppressor p53 cooperates with Smad proteins, which are TGF-β signal transducers, to selectively activate plasminogen activator inhibitor type-1 (PAI-1) transcription. p53 forms a complex with Smad2/3 in the PAI-1 promoter to recruit histone acetyltransferase CREB-binding protein (CBP) and enhance histone H3 acetylation, resulting in transcriptional activation of the PAI-1 gene. Importantly, p53 is required for TGF-β-induced cytostasis and PAI-1 is involved in the cytostatic activity of TGF-β in several cell lines. Our results suggest that p53 enhances TGF-β-induced cytostatic effects by activating PAI-1 transcription, and the functional switching of TGF-β is partially caused by p53 mutation or p53 inactivation during cancer progression. It is expected that these findings will contribute to optimization of TGF-β-targeting therapies for cancer. PMID:27759037

  4. Renal tubular injury induced by ischemia promotes the formation of calcium oxalate crystals in rats with hyperoxaluria.

    Science.gov (United States)

    Cao, Yanwei; Liu, Wanpeng; Hui, Limei; Zhao, Jianjun; Yang, Xuecheng; Wang, Yonghua; Niu, Haitao

    2016-10-01

    Hyperoxaluria and cell injury are key factors in urolithiasis. Oxalate metabolism may be altered by renal dysfunction and therefore, impact the deposition of calcium oxalate (CaOx) crystals. We investigated the relationship of renal function, oxalate metabolism and CaOx crystal deposition in renal ischemia. One hundred male Sprague-Dawley rats were randomly divided into four groups. Hyperoxaluria model (Group A and B) was established by feeding rats with 0.75 % ethylene glycol (EG). The left renal pedicle was clamped for 30 min to establish renal ischemia Groups (B and C), while Groups A and D underwent sham operation. Then, serum and urine oxalate (Ox), creatinine (Cr) and urea nitrogen (UN) levels were evaluated by liquid chromatography mass spectrometry (LCMS) and ion mass spectrum (IMS) at days 0, 2, 4, 7, and 14. CaOx crystallization was assessed by transmission electron microscope (TEM). A temporal and significant increase of serum Cr and UN levels was observed in Groups B and C compared to values obtained for Groups A and D (P renal tissue. Our results indicated that renal tubular injury induced by renal ischemia might not affect Ox levels but could promote CaOx crystal retention under hyperoxaluria.

  5. Effect of CoO on the Formation of Mullite Ceramics from Diphasic Al2O3-SiO2 Gel

    Directory of Open Access Journals (Sweden)

    N. Bandyopadhyay

    2010-01-01

    Full Text Available In this work the effect of CoO additive on the formation of mullite from Al2O3-SiO2 diphasic gel has been studied. The diphasicgel precursor for mullite was synthesized by sol-gel route following aqueous phase colloidal interaction of aluminiumhydroxide and silicic acid. The precursor gel powder was thoroughly characterized by chemical analysis, measurement ofsurface area, bulk density and also by FTIR spectroscopic studies. The gel powder was compacted with the CoO additives indifferent ratios and sintered at three different elevated temperatures. Microstructure of the sintered compacts was analyzedfrom SEM studies and phase analyses were carried out from XRD studies. It has been observed that the morphology ofthe mullite crystals changed significantly in the presence of the additives. As a result of the inclusion of additive maximumexpansion in the b-axis of the mullite crystal took place. With the addition of 3% additive more than 14% mullite formationoccurred after sintering. A significant improvement in the formation of mullite in the sintered masses was also observed inthe presence of CoO additive. More than 10% improvement in density as well as flexural strength and about 5% improvementin fracture toughness of the sintered compacts were observed in the presence of the CoO additive.

  6. Formative Evaluation of a Text Messaging Intervention to Promote Varenicline Adherence Among Tobacco-Dependent Persons with HIV.

    Science.gov (United States)

    Krebs, Paul; Tseng, Tuo-Yen; Pham, Hieu; Wong, Selena; Sherman, Scott E; Shelley, Donna; Furberg, Robert D; Wolfe, Hannah

    2015-01-01

    Few published studies describe processes in the development of mobile health interventions. This study reports data from a formative evaluation of a text messaging intervention being developed to increase adherence to smoking cessation medication (varenicline) among tobacco-dependent persons with HIV/AIDS. Four focus groups were conducted (N = 29) using a mixed-methods approach to assess: (a) beliefs and preferences regarding the use of varenicline, (b) preferences for receiving tobacco-related texts, and (c) the acceptability of draft text messages. Themes that emerged from the focus groups were that (a) participants were cautious and wanted to discuss varenicline carefully with health care providers, (b) participants preferred simple messages that were positive and encouraging, (c) messages should emphasize tobacco cessation and not varenicline adherence, and (d) texts would serve as a reminder about goals and foster support and connectedness with the health care team. Overall, 47 out of the 100 messages received a grade of C or less (rated on a 5-point grade scale: A, B, C, D, or F), the majority of which focused on medication adherence. All participants reported that they were likely to read the messages. The majority (64%) indicated that they preferred receiving 2 or more messages per day. Gathering systematic participant feedback provides critical input in intervention planning.

  7. Surface Topography and Mechanical Strain Promote Keratocyte Phenotype and Extracellular Matrix Formation in a Biomimetic 3D Corneal Model.

    Science.gov (United States)

    Zhang, Wei; Chen, Jialin; Backman, Ludvig J; Malm, Adam D; Danielson, Patrik

    2017-03-01

    The optimal functionality of the native corneal stroma is mainly dependent on the well-ordered arrangement of extracellular matrix (ECM) and the pressurized structure. In order to develop an in vitro corneal model, it is crucial to mimic the in vivo microenvironment of the cornea. In this study, the influence of surface topography and mechanical strain on keratocyte phenotype and ECM formation within a biomimetic 3D corneal model is studied. By modifying the surface topography of materials, it is found that patterned silk fibroin film with 600 grooves mm(-1) optimally supports cell alignment and ECM arrangement. Furthermore, treatment with 3% dome-shaped mechanical strain, which resembles the shape and mechanics of native cornea, significantly enhances the expression of keratocyte markers as compared to flat-shaped strain. Accordingly, a biomimetic 3D corneal model, in the form of a collagen-modified, silk fibroin-patterned construct subjected to 3% dome-shaped strain, is created. Compared to traditional 2D cultures, it supports a significantly higher expression of keratocyte and ECM markers, and in conclusion better maintains keratocyte phenotype, alignment, and fusiform cell shape. Therefore, the novel biomimetic 3D corneal model developed in this study serves as a useful in vitro 3D culture model to improve current 2D cultures for corneal studies.

  8. Promoting Ag/Al2O3 Performance in Low-Temperature H2-C3H6-SCR by Thermal Pretreatment of γ-Alumina in Water

    OpenAIRE

    Chaieb, Tesnim; Delannoy, Laurent; Louis, Catherine; Thomas, Cyril

    2016-01-01

    International audience; The present work highlights for the first time that a thermal treatment of γ-Al2O3 in water at 80 °C for 24 h prior to Ag deposition (Ag/Al2O3-OH) leads to a drastic enhancement of H2-C3H6-SCR performance at low temperature. This enhancement is attributed to the higher NOx coverage on Ag/Al2O3-OH compared with that of Ag/Al2O3. The higher NOx adsorption capacity of the sample prepared from the γ-Al2O3 thermally-treated in water is proposed to result from the preferenti...

  9. Phosphoric acid-etching promotes bond strength and formation of acid-base resistant zone on enamel.

    Science.gov (United States)

    Li, N; Nikaido, T; Alireza, S; Takagaki, T; Chen, J-H; Tagami, J

    2013-01-01

    This study examined the effect of phosphoric acid (PA) etching on the bond strength and acid-base resistant zone (ABRZ) formation of a two-step self-etching adhesive (SEA) system to enamel. An etch-and-rinse adhesive (EAR) system Single Bond (SB) and a two-step SEA system Clearfil SE Bond (SE) were used. Human teeth were randomly divided into four groups according to different adhesive treatments: 1) SB; 2) SE; 3) 35% PA etching→SE primer→SE adhesive (PA/SEp+a); (4) 35% PA etching→SE adhesive (PA/SEa). Microshear bond strength to enamel was measured and then statistically analyzed using one-way analysis of variance and the Tukey honestly significant difference test. The failure mode was recorded and analyzed by χ( 2 ) test. The etching pattern of the enamel surface was observed with scanning electron microscope (SEM). The bonded interface was exposed to a demineralizing solution (pH=4.5) for 4.5 hours and then 5% sodium hypochlorite with ultrasonication for 30 minutes. After argon-ion etching, the interfacial ultrastructure was observed using SEM. The microshear bond strength to enamel of the SE group was significantly lower (p<0.05) than that of the three PA-etched groups, although the latter three were not significantly different from one another. The ABRZ was detected in all the groups. In morphological observation, the ABRZ in the three PA-etched groups were obviously thicker compared with the SE group with an irregular wave-shaped edge.

  10. The Familial British Dementia Mutation Promotes Formation of Neurotoxic Cystine Cross-linked Amyloid Bri (ABri) Oligomers.

    Science.gov (United States)

    Cantlon, Adam; Frigerio, Carlo Sala; Freir, Darragh B; Boland, Barry; Jin, Ming; Walsh, Dominic M

    2015-07-03

    Familial British dementia (FBD) is an inherited neurodegenerative disease believed to result from a mutation in the BRI2 gene. Post-translational processing of wild type BRI2 and FBD-BRI2 result in the production of a 23-residue long Bri peptide and a 34-amino acid long ABri peptide, respectively, and ABri is found deposited in the brains of individuals with FBD. Similarities in the neuropathology and clinical presentation shared by FBD and Alzheimer disease (AD) have led some to suggest that ABri and the AD-associated amyloid β-protein (Aβ) are molecular equivalents that trigger analogous pathogenic cascades. But the sequences and innate properties of ABri and Aβ are quite different, notably ABri contains two cysteine residues that can form disulfide bonds. Thus we sought to determine whether ABri was neurotoxic and if this activity was regulated by oxidation and/or aggregation. Crucially, the type of oxidative cross-linking dramatically influenced both ABri aggregation and toxicity. Cyclization of Bri and ABri resulted in production of biologically inert monomers that showed no propensity to assemble, whereas reduced ABri and reduced Bri aggregated forming thioflavin T-positive amyloid fibrils that lacked significant toxic activity. ABri was more prone to form inter-molecular disulfide bonds than Bri and the formation of covalently stabilized ABri oligomers was associated with toxicity. These results suggest that extension of the C-terminal of Bri causes a shift in the type of disulfide bonds formed and that structures built from covalently cross-linked oligomers can interact with neurons and compromise their function and viability.

  11. Thermomineral water promotes axonal sprouting but does not reduce glial scar formation in a mouse model of spinal cord injur y

    Institute of Scientific and Technical Information of China (English)

    Dubravka Aleksi; Milan Aksi; Nevena Divac; Vidosava Radonji; Branislav Filipovi; Igor Jakovevski

    2014-01-01

    Thermomineral water from the Atomic Spa Gornja Trepča has been used for a century in the treatment of neurologic disease. The thermomineral water contains microelements, including lithium and magnesium, which show neural regeneration-promoting effects after central nervous system injury. In this study, we investigated the effects of oral intake of thermomineral water from the Atomic Spa Gornja Trepča on nerve regeneration in a 3-month-old mouse model of spinal cord injury. The mice receiving oral intake of thermomineral water showed better locomo-tor recovery than those without administration of thermomineral water at 8 and 12 weeks after lower thoracic spinal cord compression. At 12 weeks after injury, sprouting of catecholaminergic axons was better in mice that drank thermomineral water than in those without administration of thermomineral water, but there was no difference in glial reaction to injury between mice with and without administration of thermomineral water. These ifndings suggest that thermomineral water can promote the nerve regeneration but cannot reduce glial scar formation in a mouse model of spinal cord injury.

  12. UV-B Induced Generation of Reactive Oxygen Species Promotes Formation of BFA-Induced Compartments in Cells of Arabidopsis Root Apices.

    Science.gov (United States)

    Yokawa, Ken; Kagenishi, Tomoko; Baluška, František

    2015-01-01

    UV-B radiation is an important part of the electromagnetic spectrum emitted by the sun. For much of the period of biological evolution organisms have been exposed to UV radiation, and have developed diverse mechanisms to cope with this potential stress factor. Roots are usually shielded from exposure to UV by the surrounding soil, but may nevertheless be exposed to high energy radiation on the soil surface. Due to their high sensitivity to UV-B radiation, plant roots need to respond rapidly in order to minimize exposure on the surface. In addition to root gravitropism, effective light perception by roots has recently been discovered to be essential for triggering negative root phototropism in Arabidopsis. However, it is not fully understood how UV-B affects root growth and phototropism. Here, we report that UV-B induces rapid generation of reactive oxygen species which in turn promotes the formation of BFA-induced compartments in the Arabidopsis root apex. During unilateral UV-B irradiation of roots changes in auxin concentration on the illuminated side have been recorded. In conclusion, UV-B-induced and ROS-mediated stimulation of vesicle recycling promotes root growth and induces negative phototropism.

  13. UV-B induced generation of reactive oxygen species promotes formation of BFA-induced compartments in cells of Arabidopsis root apices

    Directory of Open Access Journals (Sweden)

    Ken eYokawa

    2016-01-01

    Full Text Available UV-B radiation is an important part of the electromagnetic spectrum emitted by the sun. For much of the period of biological evolution organisms have been exposed to UV radiation, and have developed diverse mechanisms to cope with this potential stress factor. Roots are usually shielded from exposure to UV by the surrounding soil, but may nevertheless be exposed to high energy radiationon the soil surface. Due to their high sensitivity to UV-B radiation, plant roots need to respond rapidly in order to minimize exposure on the surface. In addition to root gravitropism, effective light perception by roots has recently been discovered to be essential for triggering negative root phototropism in Arabidopsis. However, it is not fully understood how UV-B affects root growth and phototropism. Here, we report that UV-B induces rapid generation of reactive oxygen species which in turn promotes the formation of BFA-induced compartments in the Arabidopsis root apex. During unilateral UV-B irradiation of roots changes in auxin concentration on the illuminated side have been recorded. In conclusion, UV-B-induced and ROS-mediated stimulation of vesicle recycling promotes root growth and induces negative phototropism.

  14. Increase in Bacterial Colony Formation from a Permafrost Ice Wedge Dosed with a Tomitella biformata Recombinant Resuscitation-Promoting Factor Protein.

    Science.gov (United States)

    Puspita, Indun Dewi; Kitagawa, Wataru; Kamagata, Yoichi; Tanaka, Michiko; Nakatsu, Cindy H

    2015-01-01

    Resuscitation-promoting factor (Rpf) is a protein that has been found in a number of different Actinobacteria species and has been shown to promote the growth of active cells and resuscitate dormant (non-dividing) cells. We previously reported the biological activity of an Rpf protein in Tomitella biformata AHU 1821(T), an Actinobacteria isolated from a permafrost ice wedge. This protein is excreted outside the cell; however, few studies have investigated its contribution in environmental samples to the growth or resuscitation of bacteria other than the original host. Therefore, the aim of the present study was to determine whether Rpf from T. biformata impacted the cultivation of other bacteria from the permafrost ice wedge from which it was originally isolated. All experiments used recombinant Rpf proteins produced using a Rhodococcus erythropolis expression system. Dilutions of melted surface sterilized ice wedge samples mixed with different doses of the purified recombinant Rpf (rRpf) protein indicated that the highest concentration tested, 1250 pM, had a significantly (p <0.05) higher number of CFUs on agar plates after 8 d, approximately 14-fold higher than that on control plates without rRpf. 16S rRNA gene sequences revealed that all the colonies on plates were mainly related to Brevibacterium antiquum strain VKM Ac-2118 (AY243344), with 98-99% sequence identity. This species is also a member of the phylum Actinobacteria and was originally isolated from Siberian permafrost sediments. The results of the present study demonstrated that rRpf not only promoted the growth of T. biformata from which it was isolated, but also enhanced colony formation by another Actinobacteria in an environmental sample.

  15. Rad51/Dmc1 paralogs and mediators oppose DNA helicases to limit hybrid DNA formation and promote crossovers during meiotic recombination

    Science.gov (United States)

    Lorenz, Alexander; Mehats, Alizée; Osman, Fekret; Whitby, Matthew C.

    2014-01-01

    During meiosis programmed DNA double-strand breaks (DSBs) are repaired by homologous recombination using the sister chromatid or the homologous chromosome (homolog) as a template. This repair results in crossover (CO) and non-crossover (NCO) recombinants. Only CO formation between homologs provides the physical linkages guiding correct chromosome segregation, which are essential to produce healthy gametes. The factors that determine the CO/NCO decision are still poorly understood. Using Schizosaccharomyces pombe as a model we show that the Rad51/Dmc1-paralog complexes Rad55-Rad57 and Rdl1-Rlp1-Sws1 together with Swi5-Sfr1 play a major role in antagonizing both the FANCM-family DNA helicase/translocase Fml1 and the RecQ-type DNA helicase Rqh1 to limit hybrid DNA formation and promote Mus81-Eme1-dependent COs. A common attribute of these protein complexes is an ability to stabilize the Rad51/Dmc1 nucleoprotein filament, and we propose that it is this property that imposes constraints on which enzymes gain access to the recombination intermediate, thereby controlling the manner in which it is processed and resolved. PMID:25414342

  16. Plant Natural Product Formononetin Protects Rat Cardiomyocyte H9c2 Cells against Oxygen Glucose Deprivation and Reoxygenation via Inhibiting ROS Formation and Promoting GSK-3β Phosphorylation.

    Science.gov (United States)

    Cheng, Yuanyuan; Xia, Zhengyuan; Han, Yifan; Rong, Jianhui

    2016-01-01

    The opening of mitochondrial permeability transition pore (mPTP) is a major cause of cell death in ischemia reperfusion injury. Based on our pilot experiments, plant natural product formononetin enhanced the survival of rat cardiomyocyte H9c2 cells during oxygen glucose deprivation (OGD) and reoxygenation. For mechanistic studies, we focused on two major cellular factors, namely, reactive oxygen species (ROS) and glycogen synthase kinase 3β (GSK-3β), in the regulation of mPTP opening. We found that formononetin suppressed the formation of ROS and superoxide in a concentration-dependent manner. Formononetin also rescued OGD/reoxygenation-induced loss of mitochondrial membrane integrity. Further studies suggested that formononetin induced Akt activation and GSK-3β (Ser9) phosphorylation, thereby reducing GSK-3β activity towards mPTP opening. PI3K and PKC inhibitors abolished the effects of formononetin on mPTP opening and GSK-3β phosphorylation. Immunoprecipitation experiments further revealed that formononetin increased the binding of phosphor-GSK-3β to adenine nucleotide translocase (ANT) while it disrupted the complex of ANT with cyclophilin D. Moreover, immunofluorescence revealed that phospho-GSK-3β (Ser9) was mainly deposited in the space between mitochondria and cell nucleus. Collectively, these results indicated that formononetin protected cardiomyocytes from OGD/reoxygenation injury via inhibiting ROS formation and promoting GSK-3β phosphorylation.

  17. Plant Natural Product Formononetin Protects Rat Cardiomyocyte H9c2 Cells against Oxygen Glucose Deprivation and Reoxygenation via Inhibiting ROS Formation and Promoting GSK-3β Phosphorylation

    Directory of Open Access Journals (Sweden)

    Yuanyuan Cheng

    2016-01-01

    Full Text Available The opening of mitochondrial permeability transition pore (mPTP is a major cause of cell death in ischemia reperfusion injury. Based on our pilot experiments, plant natural product formononetin enhanced the survival of rat cardiomyocyte H9c2 cells during oxygen glucose deprivation (OGD and reoxygenation. For mechanistic studies, we focused on two major cellular factors, namely, reactive oxygen species (ROS and glycogen synthase kinase 3β (GSK-3β, in the regulation of mPTP opening. We found that formononetin suppressed the formation of ROS and superoxide in a concentration-dependent manner. Formononetin also rescued OGD/reoxygenation-induced loss of mitochondrial membrane integrity. Further studies suggested that formononetin induced Akt activation and GSK-3β (Ser9 phosphorylation, thereby reducing GSK-3β activity towards mPTP opening. PI3K and PKC inhibitors abolished the effects of formononetin on mPTP opening and GSK-3β phosphorylation. Immunoprecipitation experiments further revealed that formononetin increased the binding of phosphor-GSK-3β to adenine nucleotide translocase (ANT while it disrupted the complex of ANT with cyclophilin D. Moreover, immunofluorescence revealed that phospho-GSK-3β (Ser9 was mainly deposited in the space between mitochondria and cell nucleus. Collectively, these results indicated that formononetin protected cardiomyocytes from OGD/reoxygenation injury via inhibiting ROS formation and promoting GSK-3β phosphorylation.

  18. Au and Al Schottky barrier formation on GaAs (100) surfaces prepared by thermal desorption of a protective arsenic coating

    Energy Technology Data Exchange (ETDEWEB)

    Spindt, C.J.; Yamada, M.; Meissner, P.L.; Miyano, K.E.; Herrera, A.; Spicer, W.E. (Stanford Univ., CA (United States). Stanford Electronics Labs.); Arko, A.J. (Los Alamos National Lab., NM (United States)); Woodall, J.M.; Pettit, G.D. (International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center)

    1991-01-01

    Photoelectron spectroscopy has been used as a tool to investigate the initial stages of Schottky barrier formation on GaAs (100) surfaces. This is a popular technique that has been used by many researchers in the past to measure the band bending (or shift) of the valence band and conduction band (a measure of the Schottky barrier shift), while the Fermi level remains fixed at the system ground (i.e., the ground of the spectrometer). Metal deposition on a semiconductor surface can alter the Schottky barrier at the surface and pin the Fermi level near the middle of the energy gap. Extremely clean and crystallographically perfect surfaces are required in this study. Toward this end, a method of protecting the GaAs surface was employed which consists of capping the GaAs surface with a layer of As. Upon introduction into the high vacuum system the As is thermally desorbed, revealing a pure GaAs surface. Our work was motivated by a previous study (Brillson et al) on similarly capped specimens, which suggested that metal overlayers do not pin the Schottky barrier in GaAs. Barrier heights varied by as much as 0.75 eV between Al and Au overlayers. This large energy range is a striking result in view of the fact that a considerable number of prior studies on both (110) and (100) surfaces have found that all metals will pin within a narrow (0.25 eV) range at midgap. We repeated the measurements of Brillson on the identically doped samples used in their study using two extreme range metals of Au and Al as overlayers. We found that the barrier height measurements on low doped n-type samples used in this work and in the previous work are affected by photovoltaic effects, even at room temperature. This was determined from taking spectra at a number of temperatures between 20 K and room temperature and looking for shifts. 16 refs., 7 figs.

  19. Formation of mixed Al-Fe colloidal sorbent and dissolved-colloidal partitioning of Cu and Zn in the Cement Creek - Animas River Confluence, Silverton, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Schemel, Laurence E. [US Geological Survey, Water Resources Division, 345 Middlefield Road, MS 439, Menlo Park, CA 94025 (United States)]. E-mail: lschemel@usgs.gov; Kimball, Briant A. [US Geological Survey, Water Resources Division, 2329 Orton Circle, Salt Lake City, UT 84119-2047 (United States); Runkel, Robert L. [US Geological Survey, Water Resources Division, Denver Federal Center, MS 415, Lakewood, CO 80225 (United States); Cox, Marisa H. [US Geological Survey, Water Resources Division, 345 Middlefield Road, MS 439, Menlo Park, CA 94025 (United States)

    2007-07-15

    Transport and chemical transformations of dissolved and colloidal Al, Fe, Cu and Zn were studied by detailed sampling in the mixing zone downstream from the confluence of Cement Creek (pH 4.1) with the Animas River (pH 7.6). Complete mixing resulted in circumneutral pH in the downstream reach of the 1300 m study area. All four metals were transported through this mixing zone without significant losses to the streambed, and they exhibited transformations from dissolved to colloidal forms to varying degrees during the mixing process. Nearly all of the Al formed colloidal hydrous Al oxides (HAO) as pH increased (4.8-6.5), whereas colloidal hydrous Fe oxides (HFO) were supplied by Cement Creek as well as formed in the mixing zone primarily at higher pH (>6.5). The short travel time through the mixing zone (approx. 40 min) and pH limited the formation of HFO from dissolved Fe{sup 2+} supplied by Cement Creek. Although the proportions of HAO and HFO varied as the streams mixed, the colloidal sorbent typically was enriched in HAO relative to HFO by a factor of 1.5-2.1 (by mole) in the pH range where dissolved-to-colloidal partitioning of Cu and Zn was observed. Model simulations of sorption by HFO (alone) greatly underestimated the dissolved-to-colloidal partitioning of Zn. Previous studies have shown that HAO-HFO mixtures can sorb greater amounts of Zn than HFO alone, but the high Zn-to-sorbent ratio in this mixing zone could also account for greater partitioning. In contrast to Zn, comparisons with model simulations did not show that Cu sorption was greater than that for HFO alone, and also indicated that sorption was possibly less than what would be expected for a non-interactive mixture of these two sorbents. These field results for Cu, however, might be influenced by (organic) complexation or other factors in this natural system. Laboratory mixing experiments using natural source waters (upstream of the confluence) showed that the presence of HFO in the mixed sorbent

  20. Formation of mixed Al-Fe colloidal sorbent and dissolved-colloidal partitioning of Cu and Zn in the Cement Creek - Animas River Confluence, Silverton, Colorado

    Science.gov (United States)

    Schemel, L.E.; Kimball, B.A.; Runkel, R.L.; Cox, M.H.

    2007-01-01

    Transport and chemical transformations of dissolved and colloidal Al, Fe, Cu and Zn were studied by detailed sampling in the mixing zone downstream from the confluence of Cement Creek (pH 4.1) with the Animas River (pH 7.6). Complete mixing resulted in circumneutral pH in the downstream reach of the 1300 m study area. All four metals were transported through this mixing zone without significant losses to the streambed, and they exhibited transformations from dissolved to colloidal forms to varying degrees during the mixing process. Nearly all of the Al formed colloidal hydrous Al oxides (HAO) as pH increased (4.8-6.5), whereas colloidal hydrous Fe oxides (HFO) were supplied by Cement Creek as well as formed in the mixing zone primarily at higher pH (>6.5). The short travel time through the mixing zone (approx. 40 min) and pH limited the formation of HFO from dissolved Fe2+ supplied by Cement Creek. Although the proportions of HAO and HFO varied as the streams mixed, the colloidal sorbent typically was enriched in HAO relative to HFO by a factor of 1.5-2.1 (by mole) in the pH range where dissolved-to-colloidal partitioning of Cu and Zn was observed. Model simulations of sorption by HFO (alone) greatly underestimated the dissolved-to-colloidal partitioning of Zn. Previous studies have shown that HAO-HFO mixtures can sorb greater amounts of Zn than HFO alone, but the high Zn-to-sorbent ratio in this mixing zone could also account for greater partitioning. In contrast to Zn, comparisons with model simulations did not show that Cu sorption was greater than that for HFO alone, and also indicated that sorption was possibly less than what would be expected for a non-interactive mixture of these two sorbents. These field results for Cu, however, might be influenced by (organic) complexation or other factors in this natural system. Laboratory mixing experiments using natural source waters (upstream of the confluence) showed that the presence of HFO in the mixed sorbent

  1. Formative administration to promote the ethics of the teacher as leader of the National Program of educators' Formation in the municipality of Santa María of Ipire, State Guárico.

    Directory of Open Access Journals (Sweden)

    Sobeida Antonia Barón Guzmán

    2013-03-01

    Full Text Available At present in Venezuela, deep transformations happens, guided to the construction of a new society, based on ethical and moral values that guarantee the change in all the spheres of the country. The Bolivariana Education, as fundamental element to model the new man, through personal teaching with professional and ethical preparation, able to face the challenges that the dynamic and changing society imposes to the educational practice. The presently study intends a strategy of formative management, with the purpose of promoting the ethics of the personal teaching one that directs the National Program of Formation of Educators in the Municipality Santa María of Ipire, State Guárico, according to the demands of the education and the current society. For such effects, theoretical, empiric and statistical methods of the scientific investigation were used. The strategy was implemented in the pedagogic practice that is developed in the University Village "Antonio D' Armas Matute of the Municipality Santa María of Ipire, State Guárico whose results are evidenced positively in 85%, demonstrated in the practice of behaviors according to the ethics, on the part of the directive, so much in the classroom of classes like in the execution of the Bolivariana Professional Linking.

  2. Effect of MgCl2 addition on the sintering behavior of MgAl2O4 spinel and formation of nano-particles

    Directory of Open Access Journals (Sweden)

    Mohammadi F.

    2014-01-01

    Full Text Available In this paper, the effect of MgCl2 addition on the sintering behavior of MgAl2O4 spinel produced via oxide mixture method was investigated. For this reason, the stoichiometric mixture of magnesite and calcined alumina as raw materials was calcined at 1100°C. The calcined mixture was milled, pressed and then, fired at 1300 and 1500°C after addition of various amounts of MgCl2. Besides, the physical properties, phase composition and microstructure of fired samples were investigated. The results showed that MgCl2 addition has great effect on the densification and particle size of spinel. Besides, MgCl2 addition increases the amount of spinel phase at all firing temperatures. Due to the decomposition of MgCl2 and then formation of ultra-fine MgO particles, the nano-sized spinel is formed on the surface of the larger spinel particles.

  3. GmEXPB2, a Cell Wall β-Expansin, Affects Soybean Nodulation through Modifying Root Architecture and Promoting Nodule Formation and Development.

    Science.gov (United States)

    Li, Xinxin; Zhao, Jing; Tan, Zhiyuan; Zeng, Rensen; Liao, Hong

    2015-12-01

    Nodulation is an essential process for biological nitrogen (N2) fixation in legumes, but its regulation remains poorly understood. Here, a β-expansin gene, GmEXPB2, was found to be critical for soybean (Glycine max) nodulation. GmEXPB2 was preferentially expressed at the early stage of nodule development. β-Glucuronidase staining further showed that GmEXPB2 was mainly localized to the nodule vascular trace and nodule vascular bundles, as well as nodule cortical and parenchyma cells, suggesting that GmEXPB2 might be involved in cell wall modification and extension during nodule formation and development. Overexpression of GmEXPB2 dramatically modified soybean root architecture, increasing the size and number of cortical cells in the root meristematic and elongation zones and expanding root hair density and size of the root hair zone. Confocal microscopy with green fluorescent protein-labeled rhizobium USDA110 cells showed that the infection events were significantly enhanced in the GmEXPB2-overexpressing lines. Moreover, nodule primordium development was earlier in overexpressing lines compared with wild-type plants. Thereby, overexpression of GmEXPB2 in either transgenic soybean hairy roots or whole plants resulted in increased nodule number, nodule mass, and nitrogenase activity and thus elevated plant N and phosphorus content as well as biomass. In contrast, suppression of GmEXPB2 in soybean transgenic composite plants led to smaller infected cells and thus reduced number of big nodules, nodule mass, and nitrogenase activity, thereby inhibiting soybean growth. Taken together, we conclude that GmEXPB2 critically affects soybean nodulation through modifying root architecture and promoting nodule formation and development and subsequently impacts biological N2 fixation and growth of soybean.

  4. Chemically selective formation of Si-O-Al on SiGe(110) and (001) for ALD nucleation using H2O2(g)

    Science.gov (United States)

    Park, Sang Wook; Kim, Hyonwoong; Chagarov, Evgueni; Siddiqui, Shariq; Sahu, Bhagawan; Yoshida, Naomi; Kachian, Jessica; Feenstra, Randall; Kummel, Andrew C.

    2016-10-01

    Passivation and functionalization via atomic hydrogen, hydrogen peroxide (H2O2(g)), and trimethylaluminum (TMA) on clean silicon-germanium (Si0.5Ge0.5(110) and Si0.47Ge0.53(001)) surfaces were studied and compared at the atomic level using ultra-high vacuum (UHV) scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and X-ray photoelectron spectroscopy (XPS) to understand the topological, electronic, and chemical structures of the surfaces. STM and XPS indicate that a sputter-cleaned SiGe(110) surface is terminated with adatoms, while a SiGe(001) surface is terminated with germanium dimers. STS demonstrates that the Fermi level on a clean SiGe(110) surface is pinned near mid-gap due to surface dangling bonds, while the Fermi level on a clean SiGe(001) surface is consistent with unpinning. A saturation dose of H2O2(g) at 25 °C chemisorbs to SiGe surfaces, leaving the Fermi level at the surface consistent with unpinning, and the surface is functionalized mainly with Si-OH, Ge-OH, and Si-O-Ge bonds on both SiGe(110) and (001). After a subsequent TMA dose at 25 °C, XPS and STM verify that a thermally stable and well-ordered monolayer of Al2O3 is formed on SiGe(110) and (001) surfaces, resulting in the formation of Al-O-Si bonds. The H2O2(g) functionalization provides three times more oxygen sites on the surface and three times as great a TMA nucleation density than does H2O(g) at both 25 °C and 120 °C. STS demonstrates that H2O2(g)- and TMA-dosed SiGe surfaces show a Fermi level consistent with unpinning and a local density of states (DOS) without any states between the conduction and valence band edge, indicating an ideal template for further atomic layer deposition (ALD) nucleation of high-k materials on SiGe(110) and (001) surfaces.

  5. Effect of silicon on oxidation of Ni-15Al alloy

    Institute of Scientific and Technical Information of China (English)

    WU Ying; NIU Yan; WU Wei-tao

    2005-01-01

    The oxidation of binary Ni-Al alloy containing 15% (mole fraction, the same below if not mentioned)Al (Ni-15Al), and of a ternary alloy with the same Al content but also containing 4% Si (Ni-4Si-15Al) has been studied at 1 000 ℃ under 1.0× 105Pa O2 to examine the effect of the addition of Si on the oxidation of Ni-15Al. Oxidation of Ni-15Al produces a duplex scale composed of an outer NiO layer and an inner layer riched in Al2O3. On the contrary, Ni-4Si-15Al forms an external alumina layer directly in contact with the alloy presenting only trace of NiO and the Ni-Al spinel. As a result, the kinetics of Ni-15Al shows a fast initial stage followed by two subsequent parabolic stages with decreasing rate constants, while Ni-4Si-15Al presents essentially a single nearly-parabolic behavior with a rate constant similar to that of the final stage of Ni-15Al. Therefore, the addition of 4% Si significantly reduces the oxidation rate during the initial stage by preventing the formation of Ni-riched scales and promoting an earlier development of an exclusive external alumina layer on the alloy surface.

  6. Network Formation by Condensed Tetrahedral [Au3Al] Units in Na2Au3Al: Crystal and Electronic Structure, Spectroscopic Investigations, and Physical Properties of an Ordered Ternary Auride.

    Science.gov (United States)

    Stegemann, Frank; Benndorf, Christopher; Zhang, Yuemei; Bartsch, Manfred; Zacharias, Helmut; Fokwa, Boniface P T; Eckert, Hellmut; Janka, Oliver

    2017-02-20

    Na2Au3Al, the first experimentally prepared compound in the ternary Na-Au-Al system, crystallizes in the cubic crystal system with space group P4132 (a = 771.42(2) pm). It can be described as a P-centered ternary ordered variant of the F-centered Laves phase MgCu2 and is isostructural to Mo3Al2C. A phase width was found for the series Na2Au4-xAlx allowing a successive substitution of Au by Al. The primitive structure forms for x ≥ 0.5. Na2Au3Al is diamagnetic at room temperature but metallic in nature, as seen from susceptibility and electrical resistivity measurements. Band structure calculations and X-ray photoelectron spectroscopy confirm the metallic nature of the title compound as states are found at the Fermi level of the DOS, along with its "auride" character. (23)Na and (27)Al solid-state-NMR investigations show the existence of both a disordered (x = 0.5 and 0.75) and a fully ordered (x = 1.0) representative within this series. Both COHP and Bader charge analyses suggest the presence of strong Au-Al interactions forming an anionic [Au3Al](δ-) network, with the Na cations occupying the cavities.

  7. ARF6 promotes the formation of Rac1 and WAVE-dependent ventral F-actin rosettes in breast cancer cells in response to epidermal growth factor.

    Directory of Open Access Journals (Sweden)

    Valentina Marchesin

    Full Text Available Coordination between actin cytoskeleton assembly and localized polarization of intracellular trafficking routes is crucial for cancer cell migration. ARF6 has been implicated in the endocytic recycling of surface receptors and membrane components and in actin cytoskeleton remodeling. Here we show that overexpression of an ARF6 fast-cycling mutant in MDA-MB-231 breast cancer-derived cells to mimick ARF6 hyperactivation observed in invasive breast tumors induced a striking rearrangement of the actin cytoskeleton at the ventral cell surface. This phenotype consisted in the formation of dynamic actin-based podosome rosette-like structures expanding outward as wave positive for F-actin and actin cytoskeleton regulatory components including cortactin, Arp2/3 and SCAR/WAVE complexes and upstream Rac1 regulator. Ventral rosette-like structures were similarly induced in MDA-MB-231 cells in response to epidermal growth factor (EGF stimulation and to Rac1 hyperactivation. In addition, interference with ARF6 expression attenuated activation and plasma membrane targeting of Rac1 in response to EGF treatment. Our data suggest a role for ARF6 in linking EGF-receptor signaling to Rac1 recruitment and activation at the plasma membrane to promote breast cancer cell directed migration.

  8. Generation of free radicals from organic hydroperoxide tumor promoters in isolated mouse keratinocytes. Formation of alkyl and alkoxyl radicals from tert-butyl hydroperoxide and cumene hydroperoxide.

    Science.gov (United States)

    Taffe, B G; Takahashi, N; Kensler, T W; Mason, R P

    1987-09-05

    The organic hydroperoxides tert-butyl hydroperoxide and cumene hydroperoxide are tumor promoters in the skin of SENCAR mice, and this activity is presumed to be mediated through the activation of the hydroperoxides to free radical species. In this study we have assessed the generation of free radicals from organic hydroperoxides in the target cell (the murine basal keratinocyte) using electron spin resonance. Incubation of primary isolates of keratinocytes from SENCAR mice in the presence of spin traps (5,5-dimethyl-1-pyrroline N-oxide or 2-methyl-2-nitrosopropane) and either tert-butyl hydroperoxide or cumene hydroperoxide resulted in the generation and detection of radical adducts of these spin traps. tert-Butyl alkoxyl and alkyl radical adducts of 5,5-dimethyl-1-pyrroline N-oxide were detected shortly after addition of tert-butyl hydroperoxide, whereas only alkyl radical adducts were observed with cumene hydroperoxide. Spin trapping of the alkyl radicals with 2-methyl-2-nitrosopropane led to the identification of methyl and ethyl radical adducts following both tert-butyl hydroperoxide and cumene hydroperoxide exposures. Prior heating of the cells to 100 degrees C for 30 min prevented radical formation. The radical generating capacity of subcellular fractions of these epidermal cells was examined using 5,5-dimethyl-1-pyrroline N-oxide and cumene hydroperoxide, and this activity was confined to the 105,000 X g supernatant fraction.

  9. Analysis of Schottky Contact Formation in Coplanar Au/ZnO/Al Nanogap Radio Frequency Diodes Processed from Solution at Low Temperature.

    Science.gov (United States)

    Semple, James; Rossbauer, Stephan; Anthopoulos, Thomas D

    2016-09-01

    Much work has been carried out in recent years in fabricating and studying the Schottky contact formed between various metals and the n-type wide bandgap semiconductor zinc oxide (ZnO). In spite of significant progress, reliable formation of such technologically interesting contacts remains a challenge. Here, we report on solution-processed ZnO Schottky diodes based on a coplanar Al/ZnO/Au nanogap architecture and study the nature of the rectifying contact formed at the ZnO/Au interface. Resultant diodes exhibit excellent operating characteristics, including low-operating voltages (±2.5 V) and exceptionally high current rectification ratios of >10(6) that can be independently tuned via scaling of the nanogap's width. The barrier height for electron injection responsible for the rectifying behavior is studied using current-voltage-temperature and capacitance-voltage measurements (C-V) yielding values in the range of 0.54-0.89 eV. C-V measurements also show that electron traps present at the Au/ZnO interface appear to become less significant at higher frequencies, hence making the diodes particularly attractive for high-frequency applications. Finally, an alternative method for calculating the Richardson constant is presented yielding a value of 38.9 A cm(-2) K(-2), which is close to the theoretically predicted value of 32 A cm(-2) K(-2). The implications of the obtained results for the use of these coplanar Schottky diodes in radio frequency applications is discussed.

  10. Formation of Si-Al-Mg-Ca-rich zoned magnetite in an end-Permian phreatomagmatic pipe in the Tunguska Basin, East Siberia

    Science.gov (United States)

    Neumann, Else-Ragnhild; Svensen, Henrik H.; Polozov, Alexander G.; Hammer, Øyvind

    2017-03-01

    Magma-sediment interactions in the evaporite-rich Tunguska Basin resulted in the formation of numerous phreatomagmatic pipes during emplacement of the Siberian Traps. The pipes contain magnetite-apatite deposits with copper and celestine mineralization. We have performed a detailed petrographic and geochemical study of magnetite from long cores drilled through three pipe breccia structures near Bratsk, East Siberia. The magnetite samples are zoned and rich in Si (≤5.3 wt% SiO2), Ca, Al, and Mg. They exhibit four textural types: (1) massive ore in veins, (2) coating on breccia clasts, (3) replacement ore, and (4) reworked ore at the crater base. The textural types have different chemical characteristics. "Breccia coating" magnetite has relatively low Mg content relative to Si, as compared to the other groups, and appears to have formed at lower oxygen fugacity. Time series analyses of MgO variations in microprobe transects across Si-bearing magnetite in massive ore indicate that oscillatory zoning in the massive ore was controlled by an internal self-organized process. We suggest that hydrothermal Fe-rich brines were supplied from basalt-sediment interaction zones in the evaporite-rich sedimentary basin, leading to magnetite ore deposition in the pipes. Hydrothermal fluid composition appears to be controlled by proximity to dolerite fragments, temperature, and oxygen fugacity. Magnetite from the pipes has attributes of iron oxide-apatite deposits (e.g., textures, oscillatory zoning, association with apatite, and high Si content) but has higher Mg and Ca content and different mineral assemblages. These features are similar to magnetite found in skarn deposits. We conclude that the Siberian Traps-related pipe magnetite deposit gives insight into the metamorphic and hydrothermal effects following magma emplacement in a sedimentary basin.

  11. Enhancement on wettability and intermetallic compound formation with an addition of Al on Sn-0.7Cu lead-free solder fabricated via powder metallurgy method

    Science.gov (United States)

    Adli, Nisrin; Razak, Nurul Razliana Abdul; Saud, Norainiza

    2016-07-01

    Due to the toxicity of lead (Pb), the exploration of another possibility for lead-free solder is necessary. Nowadays, SnCu alloys are being established as one of the lead-free solder alternatives. In this study, Sn-0.7Cu lead-free solder with an addition of 1wt% and 5wt% Al were investigated by using powder metallurgy method. The effect of Al addition on the wettability and intermetallic compound thickness (IMC) of Sn-0.7Cu-Al lead-free solder were appraised. Results showed that Al having a high potential to enhance Sn-0.7Cu lead-free solder due to its good wetting and reduction of IMC thickness. The contact angle and IMC of the Sn-0.7Cu-Al lead-free solder were decreased by 14.32% and 40% as the Al content increased from 1 wt% to 5 wt%.

  12. Glass formation and mechanical properties of (Cu{sub 50}Zr{sub 50}){sub 100-x}Al{sub x} (x = 0, 4, 5, 7) bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Baser, T.A. [Dipartimento di Chimica IFM and NIS/INSTM/CNISM, University of Torino, Via P. Giuria 9, 10125 Torino (Italy); Das, J. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany); Eckert, J. [IFW Dresden, Institut fuer Komplexe Materialien, Helmholtzstrasse 20, D-01069 Dresden (Germany); TU Dresden, Institut fuer Werkstoffwissenschaft, D-01062 Dresden (Germany); Baricco, M., E-mail: marcello.baricco@unito.i [Dipartimento di Chimica IFM and NIS/INSTM/CNISM, University of Torino, Via P. Giuria 9, 10125 Torino (Italy)

    2009-08-26

    The effect of Al content on the glass formation and mechanical properties was studied for (Cu{sub 50}Zr{sub 50}){sub 100-x}Al{sub x} (x = 0, 4, 5, 7) bulk metallic glasses. The crystallization temperatures of fully amorphous Cu{sub 50}Zr{sub 50}, Cu{sub 48}Zr{sub 48}Al{sub 4}, Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} and Cu{sub 46.5}Zr{sub 46.5}Al{sub 7} as-cast rods are 724 K, 753 K, 758 K and 782 K, respectively. The mechanical properties were investigated under compression at room temperature. As-cast Cu{sub 46.5}Zr{sub 46.5}Al{sub 7} shows the highest yield strength (1867 MPa), whereas Cu{sub 47.5}Zr{sub 47.5}Al{sub 5} shows the largest fracture strain of 11.2%. The fracture surfaces of the compressed samples were investigated by scanning electron microscopy and their morphology has been correlated with the compressive plasticity.

  13. New Insight into Phase Formation of MxMg2Al(4+x)Si(5-x)O18:Eu2+ Solid Solution Phosphors and Its Luminescence Properties.

    Science.gov (United States)

    Zhou, Jun; Xia, Zhiguo; Chen, Mingyue; Molokeev, Maxim S; Liu, Quanlin

    2015-07-20

    Here we reported the phase formation of MxMg2Al(4+x)Si(5-x)O18:Eu(2+) (M = K, Rb) solid solution phosphors, where M(+) ions were introduced into the void channels of Mg2Al4Si5O18 via Al(3+)/Si(4+) substitution to keep the charge balance. XRD results revealed that the as-prepared phosphors with different M(+) contents were iso-structural with Mg2Al4Si5O18 phase. The combined analysis of the Rietveld refinement and high resolution transmission electron microscopy (HRTEM) results proved that M(+) ions were surely introduced into the intrinsic channels in Mg2Al4Si5O18. The emission peaks of MxMg2Al(4+x)Si(5-x)O18:Eu(2+) (M = K, Rb) phosphors with various x values performed a systematic red-shift tendency, which was ascribed to the elongation of [MgO6] octahedra. The temperature stable photoluminescence and internal quantum efficiency (QE) of MxMg2Al(4+x)Si(5-x)O18:Eu(2+) (M = K, Rb) phosphors were enhanced owing to the filling of M(+) in the void channels suggesting a new insight to design the solid solution phosphors with improved photoluminescence properties.

  14. Formation of CoAl2O4 Nanoparticles via Low-Temperature Solid-State Reaction of Fine Gibbsite and Cobalt Precursor

    OpenAIRE

    Natpakan Srisawad; Wasu Chaitree; Okorn Mekasuwandumrong; Piyasan Praserthdam; Joongjai Panpranot

    2012-01-01

    Nanocrystalline cobalt aluminate (CoAl2O4) was synthesized by the solid-state reaction method with cobalt chloride hexahydrate (CoCl2 · 6H2O) as the source of Co and gibbsite (Al(OH)3) as the source of Al, respectively. The effects of particle size of the starting fine gibbsite (0.6 and 13 μm) and calcination temperatures (450, 550, and 650°C) on the properties of CoAl2O4 were investigated by means of X-ray diffraction (XRD), thermogravimetry analysis and differential thermal analysis (TG/DT...

  15. Hybrid use of combined and sequential delivery of growth factors and ultrasound stimulation in porous multilayer composite scaffolds to promote both vascularization and bone formation in bone tissue engineering.

    Science.gov (United States)

    Yan, Haoran; Liu, Xia; Zhu, Minghua; Luo, Guilin; Sun, Tao; Peng, Qiang; Zeng, Yi; Chen, Taijun; Wang, Yingying; Liu, Keliang; Feng, Bo; Weng, Jie; Wang, Jianxin

    2016-01-01

    In this study, a multilayer coating technology would be adopted to prepare a porous composite scaffold and the growth factor release and ultrasound techniques were introduced into bone tissue engineering to finally solve the problems of vascularization and bone formation in the scaffold whilst the designed multilayer composite with gradient degradation characteristics in the space was used to match the new bone growth process better. The results of animal experiments showed that the use of low intensity pulsed ultrasound (LIPUS) combined with growth factors demonstrated excellent capabilities and advantages in both vascularization and new bone formation in bone tissue engineering. The degradation of the used scaffold materials could match new bone formation very well. The results also showed that only RGD-promoted cell adhesion was insufficient to satisfy the needs of new bone formation while growth factors and LIPUS stimulation were the key factors in new bone formation.

  16. /Cu-Al System

    Science.gov (United States)

    Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum

    2014-05-01

    Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50°) is determined by Ta adsorption on the newly formed alumina interlayer.

  17. Promotional effects of cerium doping and NOx on the catalytic soot combustion over MnMgAlO hydrotalcite-based mixed oxides

    Institute of Scientific and Technical Information of China (English)

    李倩; 王晓; 常伟; 陈慧; 张昭良

    2014-01-01

    A series of MnMgAlO samples with different amounts of Ce doping were facilely prepared using coprecipitation method and their catalytic soot combustion activity was evaluated by temperature programmed oxidation reaction (TPO). The methods of X-ray diffraction (XRD), Brumauer-Emmett-Teller (BET), H2-TPR, NO-TPO and in situ IR were used to characterize the physio-chemical properties of these samples. Dopant Ce improved the soot combustion performance of MnMgAlO catalyst due to the en-hanced redox ability. Introduction of NOx led to the further increase of catalytic soot oxidation activity on these samples. Over Ce-containing samples, the catalytic activity was slightly decreased as the amount of dopant Ce increased in O2. Differently, in NO+O2, a certain amount of dopant Ce was much more favorable and excess amount of Ce resulted in a sharp drop of the catalytic soot combustion activity. Both NO2 and nitrates were found to have great contributions to the effects of NOx on the soot combustion activity of Ce-doped catalysts. More NO2 was generated as dopant Ce increased. When appropriate amount of Ce was introduced, the as-formed NO2 was stored as bridging bidentate nitrate on Mn-Ce site, which was confirmed to have higher reactivity with soot than nitrite or monodentate nitrate on Mn and/or Ce sites. Overall, Mn0.5Mg2.5Ce0.1Al0.9O was considered as the most potential catalyst for soot combustion.

  18. Formation Mechanism of CaO-SiO2-Al2O3-(MgO) Inclusions in Si-Mn-Killed Steel with Limited Aluminum Content During the Low Basicity Slag Refining

    Science.gov (United States)

    Wang, Kunpeng; Jiang, Min; Wang, Xinhua; Wang, Ying; Zhao, Haoqian; Cao, Zhanmin

    2016-02-01

    Pilot trails were carried out to study the formation mechanism of CaO-SiO2-Al2O3-(MgO) inclusions in tire cord steel. 48 samples were taken from 8 heats of liquid steel during secondary refining, which were subsequently examined by an automatic scanning electron microscope with energy dispersive spectrometer (SEM-EDS). Characteristics of thousands of oxide inclusions at different refining stages were obtained, including their compositions, sizes, morphologies, etc. Based on the obtained information of inclusions, details during formation of CaO-SiO2-Al2O3-(MgO) inclusions were revealed and a new mechanism was proposed, including their origin, formation, and evolution during the refining process. It was found that CaO-SiO2-Al2O3-(MgO) inclusions were initially originated from the CaO-SiO2-MnO-(MgO) inclusions, which were formed during BOF tapping by the coalescence between MnO-SiO2 deoxidation products and the emulsified slag particles because of violent flow of steel. This can be well confirmed by the evaluation of the formation thermodynamics of CaO-SiO2-MnO-(MgO) inclusions, which was proved very difficult to be produced by intrinsic reactions inside liquid steel. Because of chemical reactions between CaO-SiO2-MnO-(MgO) inclusions and molten steel, they were mainly changed into CaO-SiO2-MnO-Al2O3-(MgO) and partially into CaO-SiO2-Al2O3-(MgO), which may be detrimental to the cold drawing ability of coils. Based on this finding, improvements were made in industrial production during BOF tapping and secondary refining. The results indicated that such (CaO-SiO2)-based inclusions existed in conventional process were effectively decreased after the improvements.

  19. Selective hydrogenation of benzyl cyanide to 2-phenylethylamine over a Pd/Al2O3 catalyst promoted by synergistic effects of CO2 and water

    OpenAIRE

    2015-01-01

    The selective hydrogenation of benzyl cyanide (BC) to the primary amine of 2-phenylethylamine (PEA) was investigated with a Pd/Al2O3 catalyst in different multiphase reaction media including n-hexane, water, and/or CO2. In neat n-hexane, the hydrogenation of BC occurs at a large rate but no PEA was formed and the secondary amine of N, N-bis(2-phenylethyl) amine (BPEA) was produced as the main product. The pressurization of n-hexane with CO2 decreased the rate of hydrogenation and the main pro...

  20. Methane reforming With CO2 to syngas over CeO2-promoted Ni/Al2O3-ZrO2 catalysts Prepared Via a direct sol-gel process

    Institute of Scientific and Technical Information of China (English)

    Hansheng Li; Hang Xu; Jinfu Wang

    2011-01-01

    CeO2-promoted Ni/Al2O3-ZrO2 (Ni/Al2O3-ZrO2-CeO2) catalysts were prepared by a direct sol-gel process with citric acid as gelling agent.The catalysts used for the methane reforming with CO2 was studied by infrared spectroscopy (IR), thermal gravimetric analysis (TGA), microscopic analysis, X-ray diffraction (XRD) and temperature-programmed reduction (TPR).The catalytic performance for CO2 reforming of methane to synthesis gas was investigated in a continuous-flow micro-reactor under atmospheric pressure.TGA, IR, XRD and microscopic analysis show that the catalysts prepared by the direct sol-gel process consist of Ni particles with a nanostructure of around 5 nm and an amorphous-phase composite oxide support.There exists a chemical interaction between metallic Ni particles and supports, which makes metallic Ni well dispersed, highly active and stable.The addition of CeO2 effectively improves the dispersion and the stability of Ni particles of the prepared catalysts, and enhances the adsorption of CO2 on the surface of catalysts.The catalytic tests for methane reforming with CO2 to synthesis gas show that the Ni/Al2O3-ZrO2-CeO2 catalysts show excellent activity and stability compared with the Ni/Al2O3 catalyst.The excellent catalytic activity and stability of the Ni/Al2O3-ZrO2-CeO2 are attributed to the highly, uniformly and stably dispersed small metallic Ni particles, the high reducibility of the Ni oxides and the interaction between metallic Ni particles and the composite oxide supports.

  1. Using poly(lactic-co-glycolic acid microspheres to encapsulate plasmid of bone morphogenetic protein 2/polyethylenimine nanoparticles to promote bone formation in vitro and in vivo

    Directory of Open Access Journals (Sweden)

    Qiao C

    2013-08-01

    Full Text Available Chunyan Qiao,1,* Kai Zhang,2,* Han Jin,1 Leiying Miao,3 Ce Shi,1 Xia Liu,1 Anliang Yuan,1 Jinzhong Liu,1 Daowei Li,1 Changyu Zheng,4 Guirong Zhang,5 Xiangwei Li,1 Bai Yang,2 Hongchen Sun11Department of Pathology, School of Stomatology, Jilin University, Changchun, 2State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 3Institute and Hospital of Stomatology, Nanjing University Medical School, Nanjing, People's Republic of China; 4Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA; 5Department of Biochemistry, School of Basic Medicine, Jilin University, Changchun, People's Republic of China*These authors contributed equally to this workAbstract: Repair of large bone defects is a major challenge, requiring sustained stimulation to continually promote bone formation locally. Bone morphogenetic protein 2 (BMP-2 plays an important role in bone development. In an attempt to overcome this difficulty of bone repair, we created a delivery system to slowly release human BMP-2 cDNA plasmid locally, efficiently transfecting local target cells and secreting functional human BMP-2 protein. For transfection, we used polyethylenimine (PEI to create pBMP-2/PEI nanoparticles, and to ensure slow release we used poly(lactic-co-glycolic acid (PLGA to create microsphere encapsulated pBMP-2/PEI nanoparticles, PLGA@pBMP-2/PEI. We demonstrated that pBMP-2/PEI nanoparticles could slowly release from the PLGA@pBMP-2/PEI microspheres for a long period of time. The 3–15 µm diameter of the PLGA@pBMP-2/PEI further supported this slow release ability of the PLGA@pBMP-2/PEI. In vitro transfection assays demonstrated that pBMP-2/PEI released from PLGA@pBMP-2/PEI could efficiently transfect MC3T3-E1 cells, causing MC3T3-E1 cells to secrete human BMP-2 protein, increase calcium deposition and gene expressions of alkaline

  2. Microstructure formation and interface characteristics of directionally solidified TiAl-Si alloys in alumina crucibles with a new Y2O3 skull-aided technology

    Science.gov (United States)

    Fan, Jianglei; Liu, Jianxiu; Wu, Shen; Tian, Shuxia; Gao, Hongxia; Wang, Shengyong; Guo, Jingjie; Wang, Xiao

    2017-03-01

    The microstructure evolution and interface characteristics of a directionally solidified Ti-43Al-3Si (at.%) alloy in an alumina (Al2O3) crucible with new Y2O3 skull-aided technology were investigated. The Y2O3-skull that is in contact with the TiAl-melt is relatively stable, which results in a more controlled reaction between the skull and the melt than in the case of an Al2O3 crucible is used. A thin reaction layer was formed between the mould and the melt through mutual diffusion. The layer thickness increased with increasing reaction time. The thickness of this layer was less than 80 μm for reaction times up to 5800 s. Y2O3 particles were not found in the specimen because the mould coating was prepared with fine Y2O3 powder without a binder, which prevented the Y2O3 particles splitting from the coating as a consequence of thermal physical erosion. The oxygen content of the TiAl-alloy increased with increasing reaction time. The total oxygen content of the solidified specimen was less than that of the specimen solidified in the Al2O3 crucibles. This new Y2O3 skull-aided technology is expected to improve the surface quality of TiAl-alloys and reduce the reaction between the crucible/mould and molten TiAl alloys during directional solidification processing with longer contact times.

  3. The neuronal differentiation factor NeuroD1 downregulates the neuronal repellent factor Slit2 expression and promotes cell motility and tumor formation of neuroblastoma.

    Science.gov (United States)

    Huang, Peng; Kishida, Satoshi; Cao, Dongliang; Murakami-Tonami, Yuko; Mu, Ping; Nakaguro, Masato; Koide, Naoshi; Takeuchi, Ichiro; Onishi, Akira; Kadomatsu, Kenji

    2011-04-15

    The basic helix-loop-helix transcription factor NeuroD1 has been implicated in the neurogenesis and early differentiation of pancreatic endocrine cells. However, its function in relation to cancer has been poorly examined. In this study, we found that NeuroD1 is involved in the tumorigenesis of neuroblastoma. NeuroD1 was strongly expressed in a hyperplastic region comprising neuroblasts in the celiac sympathetic ganglion of 2-week-old MYCN transgenic (Tg) mice and was consistently expressed in the subsequently generated neuroblastoma tissue. NeuroD1 knockdown by short hairpin RNA (shRNA) resulted in motility inhibition of the human neuroblastoma cell lines, and this effect was reversed by shRNA-resistant NeuroD1. The motility inhibition by NeuroD1 knockdown was associated with induction of Slit2 expression, and knockdown of Slit2 could restore cell motility. Consistent with this finding, shRNA-resistant NeuroD1 suppressed Slit2 expression. NeuroD1 directly bound to the first and second E-box of the Slit2 promoter region. Moreover, we found that the growth of tumor spheres, established from neuroblastoma cell lines in MYCN Tg mice, was suppressed by NeuroD1 suppression. The functions identified for NeuroD1 in cell motility and tumor sphere growth may suggest a link between NeuroD1 and the tumorigenesis of neuroblastoma. Indeed, tumor formation of tumor sphere-derived cells was significantly suppressed by NeuroD1 knockdown. These data are relevant to the clinical features of human neuroblastoma: high NeuroD1 expression was closely associated with poor prognosis. Our findings establish the critical role of the neuronal differentiation factor NeuroD1 in neuroblastoma as well as its functional relationship with the neuronal repellent factor Slit2.

  4. The congenital cataract-linked A2V mutation impairs tetramer formation and promotes aggregation of βB2-crystallin.

    Directory of Open Access Journals (Sweden)

    Jia Xu

    Full Text Available β/γ-Crystallins, the major structural proteins in human lens, are highly conserved in their tertiary structures but distinct in the quaternary structures. The N- and C-terminal extensions have been proposed to play a crucial role in mediating the size of β-crystallin assembly. In this research, we investigated the molecular mechanism underlying the congenital hereditary cataract caused by the recently characterized A2V mutation in βB2-crystallin. Spectroscopic experiments indicated that the mutation did not affect the secondary and tertiary structures of βB2-crystallin. The mutation did not affect the formation of βB2/βA3-crystallin heteromer as well as the stability and folding of the heteromer, suggesting that the mutation might not interfere with the protein interacting network in the lens. However, the tetramerization of βB2-crystallin at high protein concentrations was retarded by the A2V mutation. The mutation slightly decreased the thermal stability and promoted the thermal aggregation of βB2-crystallin. Although it did not influence the stability of βB2-crystallin against denaturation induced by chemical denaturants and UV irradiation, the A2V mutant was more prone to be trapped in the off-pathway aggregation process during kinetic refolding. Our results suggested that the A2V mutation might lead to injury of lens optical properties by decreasing βB2-crystallin stability against heat treatment and by impairing βB2-crystallin assembly into high-order homo-oligomers.

  5. Translating formative research findings into a behaviour change strategy to promote antenatal calcium and iron and folic acid supplementation in western Kenya.

    Science.gov (United States)

    Martin, Stephanie L; Seim, Gretchen L; Wawire, Salome; Chapleau, Gina M; Young, Sera L; Dickin, Katherine L

    2017-01-01

    The World Health Organization now recommends integrating calcium supplements into antenatal micronutrient supplementation programmes to prevent pre-eclampsia, a leading cause of maternal mortality. As countries consider integrating calcium supplementation into antenatal care (ANC), it is important to identify context-specific barriers and facilitators to delivery and adherence. Such insights can be gained from women's and health workers' experiences with iron and folic acid (IFA) supplements. We conducted in-depth interviews with 22 pregnant and post-partum women and 20 community-based and facility-based health workers in Kenya to inform a calcium and IFA supplementation programme. Interviews assessed awareness of anaemia, pre-eclampsia and eclampsia; ANC attendance; and barriers and facilitators to IFA supplement delivery and adherence. We analyzed interviews inductively using the constant comparative method. Women and health workers identified poor diet quality in pregnancy as a major health concern. Neither women nor health workers identified pre-eclampsia, eclampsia, anaemia or related symptoms as serious health threats. Women and community-based health workers were unfamiliar with pre-eclampsia and eclampsia and considered anaemia symptoms normal. Most women had not received IFA supplements, and those who had received insufficient amounts and little information about supplement benefits. We then developed a multi-level (health facility, community, household and individual) behaviour change strategy to promote antenatal calcium and IFA supplementation. Formative research is an essential first step in guiding implementation of antenatal calcium supplementation programmes to reduce pre-eclampsia. Because evidence on how to implement successful calcium supplementation programmes is limited, experiences with antenatal IFA supplementation can be used to guide programme development.

  6. Formation and Structure of [Al13(μ3-OH)6(μ2-OH)6(μ2-OH)12(H2O)24]Cl15· 13H2O

    Institute of Scientific and Technical Information of China (English)

    SUN Zhong; ZHAO Hai-Dong; TONG Hong-Ge-Er; WANG Rui-Fen; ZHU Fan-Zhu

    2006-01-01

    Crystal structure of a novel hydrated tridecameric polyaluminium chloride, [Al13(μ3-obtaining the detailed structural parameters and structure features. Moreover, the formation course was also discussed. The crystal belongs to monoclinic system, space group P21/c, with a =1.3912(2), b = 2.3529(3), c = 2.2395(2) nm, β= 90.407(2)°, V= 7.3307(14) nm3, Z = 4, Dc = 1.773g/cm3, F(000) = 4040, GOOF = 1.050, t(MoKα) = 0.829 mm-1, the final R = 0.0506 and wR =0.1453 for 10553 observed reflections with I > 2σ(I). The structure of polycation of the title compound is different from either Keggin-type Al13 consisting of a central tetrahedral AlO4 core surrounded by twelve octahedral AlO6 units through comer-sharing or the "three hexameric rings juxtaposed" side by side predicted by "Core-Links" model linked by thirteen octahedral AlO6 units through edge-sharing. It has a "tortoise-like" structure with turnup "forefeet" and "tail", that is, an octahedral AlO6 core is surrounded by a "hexameric ring" through edge-sharing, then six octahedral AlO6 units are suspended onto the periphery of the ring upper and lower alternately by sharing two neighboring corners with an average turn angle of 21° entad. This kind of hydrated tridecameric polyaluminium chloride with such form is very important to further understand the existing forms and transformation rules of aluminium ion in hydrolysis system of its salts, speculate the process and mechanism of various hydrolysis and polymerization forms from Al(H2O)63+ to Al(OH)3, and establish the relationship between structure and properties.

  7. Formation of quasicrystals and amorphous-to-quasicrystalline phase transformation kinetics in Zr65Al7.5Ni10Cu7.5Ag10 metallic glass under pressure

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Zhuang, Yanxin; Rasmussen, Helge Kildahl

    2001-01-01

    The effect of pressure on the formation of quasicrystals and the amorphous-to-quasicrystalline phase transformation kinetics in the supercooled liquid region for a Zr65Al7.5Ni10Cu7.5Ag10 metallic glass have been investigated by in situ high-pressure and high-temperature nonisothermal and isothermal...... of quasicrystals decrease, Atomic mobility is important for the formation of quasicrystals from the metallic glass whereas the relationship of the crystallization temperature vs pressure for the transition from the quasicrystalline state to intermetallic compounds may mainly depend on the thermodynamic potential...

  8. Effect of InAlGaAs and GaAs combination barrier thickness on the duration of dot formation in different layers of stacked InAs/GaAs quantum dot heterostructure grown by MBE.

    Science.gov (United States)

    Halder, N; Suseendran, J; Chakrabarti, S; Herrera, Miriam; Bonds, Marta; Browning, Nigel D

    2010-08-01

    Multilayer stacks of quantum dots (QDs) (10 periods) with a combination barrier layer of In0.21Al0.21 Ga0.58As (30 angstroms) and GaAs (70-180 angstroms) are grown by solid source molecular beam epitaxy (MBE) and reflection high-energy electron diffraction (RHEED) has been used for the in situ determination of the duration of dot formation in the QD layers. The increase in the duration of dot formation in the consecutive layers of the QD heterostructure with thinner barrier is attributed to the indium migration towards the defects in the strained QD layers. A thicker GaAs layer at 590 degrees C overgrown on the InAlGaAs is believed to remove the unevenness of the growth front for the subsequent QD layer resulting in good vertical stacking of islands till the final layer of the multilayer heterostructures.

  9. FEATURES OF STRUCTURE FORMATION AND CHANGES IN THE MECHANICAL PROPERTIES OF CAST Al-Mg-Si-Mn ALLOY WITH THE ADDITION OF (Ti+Zr

    Directory of Open Access Journals (Sweden)

    Oleksandr Trudonoshyn

    2015-08-01

    Full Text Available The as-cast and heat-treated structure of permanent mould castings of AlMg5Si2Mn alloys with different contents of Ti has been investigated by differential scanning calorimetry, hardness and microhardness measurements, tensile tests and fractography analyses, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. We have established that α-Al dendrites can be nucleated on an Al-Ti substrate, and also that primary Mg2Si crystals can be nucleated on oxides, including oxides of Al and Ti compounds. The dependence of the change in mechanical properties on ageing time, and on the amount of Ti in the alloys, is shown.

  10. The formation of tungsten doped Al2O3/ZnO coatings on aluminum by plasma electrolytic oxidation and their application in photocatalysis

    Science.gov (United States)

    Stojadinović, Stevan; Vasilić, Rastko; Radić, Nenad; Tadić, Nenad; Stefanov, Plamen; Grbić, Boško

    2016-07-01

    Tungsten doped Al2O3/ZnO coatings are formed by plasma electrolytic oxidation of aluminum substrate in supporting electrolyte (0.1 M boric acid + 0.05 M borax + 2 g/L ZnO) with addition of different concentrations of Na2WO4·2H2O. The morphology, crystal structure, chemical composition, and light absorption characteristics of formed surface coatings are investigated. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that formed surface coatings consist of alpha and gamma phase of Al2O3, ZnO, metallic tungsten and WO3. Obtained results showed that incorporated tungsten does not have any influence on the absorption spectra of Al2O3/ZnO coatings, which showed invariable band edge at about 385 nm. The photocatalytic activity of undoped and tungsten doped Al2O3/ZnO coatings is estimated by the photodegradation of methyl orange. The photocatalytic activity of tungsten doped Al2O3/ZnO coatings is higher thanof undoped Al2O3/ZnO coatings; the best photocatalytic activity is ascribed to coatings formed in supporting electrolyte with addition of 0.3 g/L Na2WO4·2H2O. Tungsten in Al2O3/ZnO coatings acts as a charge trap, thus reducing the recombination rate of photogenerated electron-hole pairs. The results of PL measurements are in agreement with photocatalytic activity. Declining PL intensity corresponds to increasing photocatalytic activity of the coatings, indicating slower recombination of electron-hole pairs.

  11. The formation and acceptor related emission behavior of ZnO/ZnAl{sub 2}O{sub 4} core–shell structures

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.Y.; Li, J.H., E-mail: lijinhua2000@yahoo.com.cn; Sun, Z.H.; Fang, X.; Wei, Z.P.; Fang, F.; Chu, X.Y.; Li, S.; Wang, X.H.

    2013-09-15

    Highlights: •Based on Kirkendall effect, a ZnO/ZnAl{sub 2}O{sub 4} core–shell nanostructure were fabricated. •Discussed the original of the PL spectrum in detail. •A A{sup 0}X emission peak was observed. •Realize a undoped p-type ZnO. -- Abstract: In this paper, ZnO nanorods were grown on Si substrate with hydrothermal method, followed by Al{sub 2}O{sub 3} and ZnO thin layers deposited on ZnO nanorods by atomic layer deposition, a coated nanocomposite structure ZnO/Al{sub 2}O{sub 3}/ZnO nanorods were obtained. Based on Kirkendall effect, ZnO/ZnAl{sub 2}O{sub 4} core–shell nanostructure were fabricated by annealing treatment through an interfacial solid-state reaction between ZnO and Al{sub 2}O{sub 3}, which were confirmed by X-ray diffraction spectra. In this process, due to that Zn ions diffused into Al{sub 2}O{sub 3} and formed ZnAl{sub 2}O{sub 4}, Zn vacancies were introduced in ZnO. In PL spectra, the emission related to acceptor located at 3.355 eV and 3.315 eV can be observed, which were attributed to A{sup 0}X and FA emission, respectively. The calculated acceptor binding energy is 118 meV.

  12. The formation of tungsten doped Al{sub 2}O{sub 3}/ZnO coatings on aluminum by plasma electrolytic oxidation and their application in photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Stojadinović, Stevan, E-mail: sstevan@ff.bg.ac.rs [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Vasilić, Rastko [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Radić, Nenad [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia); Tadić, Nenad [University of Belgrade, Faculty of Physics, Studentski trg 12-16, 11000 Belgrade (Serbia); Stefanov, Plamen [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, 1113 Sofia (Bulgaria); Grbić, Boško [University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Catalysis and Chemical Engineering, Njegoševa 12, 11000 Belgrade (Serbia)

    2016-07-30

    Highlights: • Tungsten doped Al{sub 2}O{sub 3}/ZnO coatings are formed by plasma electrolytic oxidation (PEO). • Coatings are mainly composed of alpha alumina, ZnO and metallic tungsten. • Photocatalytic activity of doped Al{sub 2}O{sub 3}/ZnO coatings is higher than of undoped ones. • The increase of photoluminescence corresponds to decrease of photocatalytic activity. • Tungsten acts as a charge trap to reduce the recombination rate of electron/hole pairs. - Abstract: Tungsten doped Al{sub 2}O{sub 3}/ZnO coatings are formed by plasma electrolytic oxidation of aluminum substrate in supporting electrolyte (0.1 M boric acid + 0.05 M borax + 2 g/L ZnO) with addition of different concentrations of Na{sub 2}WO{sub 4}·2H{sub 2}O. The morphology, crystal structure, chemical composition, and light absorption characteristics of formed surface coatings are investigated. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that formed surface coatings consist of alpha and gamma phase of Al{sub 2}O{sub 3}, ZnO, metallic tungsten and WO{sub 3}. Obtained results showed that incorporated tungsten does not have any influence on the absorption spectra of Al{sub 2}O{sub 3}/ZnO coatings, which showed invariable band edge at about 385 nm. The photocatalytic activity of undoped and tungsten doped Al{sub 2}O{sub 3}/ZnO coatings is estimated by the photodegradation of methyl orange. The photocatalytic activity of tungsten doped Al{sub 2}O{sub 3}/ZnO coatings is higher thanof undoped Al{sub 2}O{sub 3}/ZnO coatings; the best photocatalytic activity is ascribed to coatings formed in supporting electrolyte with addition of 0.3 g/L Na{sub 2}WO{sub 4}·2H{sub 2}O. Tungsten in Al{sub 2}O{sub 3}/ZnO coatings acts as a charge trap, thus reducing the recombination rate of photogenerated electron-hole pairs. The results of PL measurements are in agreement with photocatalytic activity. Declining PL intensity corresponds to increasing photocatalytic activity of the

  13. Formation of SiGe nanocrystals embedded in Al2O3 for the application of write-once-read-many-times memory

    Science.gov (United States)

    Wu, Min-Lin; Wu, Yung-Hsien; Lin, Chia-Chun; Chen, Lun-Lun

    2012-10-01

    The structure of SiGe nanocrystals embedded in Al2O3 formed by sequential deposition of Al2O3/Si/Ge/Al2O3 and a subsequent annealing was confirmed by transmission electron microscopy and energy dispersive spectroscopy (EDS), and its application for write-once-read-many-times (WORM) memory devices was explored in this study. By applying a -10 V pulse for 1 s, a large amount of holes injected from Si substrate are stored in the nanocrystals and consequently, the current at +1.5 V increases by a factor of 104 as compared to that of the initial state. Even with a smaller -5 V pulse for 1 μs, a sufficiently large current ratio of 36 can still be obtained, verifying the low power operation. Since holes are stored in nanocrystals which are isolated from Si substrate by Al2O3 with good integrity and correspond to a large valence band offset with respect to Al2O3, desirable read endurance up to 105 cycles and excellent retention over 100 yr are achieved. Combining these promising characteristics, WORM memory devices are appropriate for high-performance archival storage applications.

  14. Formation of SiGe nanocrystals embedded in Al{sub 2}O{sub 3} for the application of write-once-read-many-times memory

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Min-Lin; Wu, Yung-Hsien; Lin, Chia-Chun; Chen, Lun-Lun [Department of Engineering and System Science, National Tsing-Hua University, 300 Hsinchu, Taiwan (China)

    2012-10-15

    The structure of SiGe nanocrystals embedded in Al{sub 2}O{sub 3} formed by sequential deposition of Al{sub 2}O{sub 3}/Si/Ge/Al{sub 2}O{sub 3} and a subsequent annealing was confirmed by transmission electron microscopy and energy dispersive spectroscopy (EDS), and its application for write-once-read-many-times (WORM) memory devices was explored in this study. By applying a -10 V pulse for 1 s, a large amount of holes injected from Si substrate are stored in the nanocrystals and consequently, the current at +1.5 V increases by a factor of 10{sup 4} as compared to that of the initial state. Even with a smaller -5 V pulse for 1 {mu}s, a sufficiently large current ratio of 36 can still be obtained, verifying the low power operation. Since holes are stored in nanocrystals which are isolated from Si substrate by Al{sub 2}O{sub 3} with good integrity and correspond to a large valence band offset with respect to Al{sub 2}O{sub 3}, desirable read endurance up to 10{sup 5} cycles and excellent retention over 100 yr are achieved. Combining these promising characteristics, WORM memory devices are appropriate for high-performance archival storage applications.

  15. A sessile drop setup for the time-resolved synchrotron study of solid-liquid interactions: Application to intermetallic formation in 55%Al-Zn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bernier, N., E-mail: n.bernier@yahoo.fr; De Bruyn, D.; De Craene, M.; Scheers, J.; Claessens, S. [OCAS N.V., ArcelorMittal Global R and D Gent, Pres. J.F. Kennedylaan 3, 9060 Zelzate (Belgium); Vaughan, G. B. M.; Vitoux, H.; Gleyzolle, H.; Gorges, B. [European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex (France)

    2014-04-28

    We introduce a dedicated setup for measuring by synchrotron diffraction in-situ crystallographic and chemical information at the solid–liquid interface. This setup mostly consists of a double-heating furnace composed of a resistive heating for the solid surface and an inductive heating to produce a liquid droplet. The available high energy and high flux beams allow the rapid reaction kinetics to be investigated with very good time resolution down to 1 ms. An application of this setup is illustrated for the growth mechanisms of intermetallic phases during the hot-dipping of steel in a 55%Al-Zn bath. Results show that the three η-Al{sub 5}Fe{sub 2}, θ-Al{sub 13}Fe{sub 4}, and α-Al{sub 8}Fe{sub 2}Si phases grow at different times and rates during the dipping process, whereas the face-centered cubic AlFe{sub 3} phase is not formed.

  16. Nb/sub 3/Al formation at temperatures lower than 1000/sup 0/C. [J/sub c/ and T/sub c/

    Energy Technology Data Exchange (ETDEWEB)

    Ceresara, S. (ISML, Novara, Italy); Ricci, M.V.; Sacchetti, N.; Sacerdoti, G.

    1975-03-01

    A study was made of the possibility of making Nb/sub 3/Al wires by interdiffusion between Al and Nb at relatively low temperatures (lower than 1000/sup 0/C). This method should allow the fabrication of a copper stabilized wire by coworking Nb and Al composites in a copper matrix before the diffusion treatment. Results concerning the diffusion temperature and time dependence of J/sub c/ and T/sub c/ are presented. While J/sub c/(64 kG) is quite high, of the order of 1.5 x 10/sup 5/ A/cm/sup 2/, T/sub c/ is 15.56/sup 0/K, lower than the usually reported value. X-ray measurements of the lattice parameter are also reported and correlated with the measured value of T/sub c/.

  17. Bioactivity of Ti-6Al-4V alloy implants treated with ibandronate after the formation of the nanotube TiO2 layer.

    Science.gov (United States)

    Moon, So-Hee; Lee, Seung-Jae; Park, Il-Song; Lee, Min-Ho; Soh, Yun-Jo; Bae, Tae-Sung; Kim, Hyung-Seop

    2012-11-01

    Nanostructure surface of titanium implants treated with anodic oxidation, heat, and bisphosphonates, has been introduced to improve osseointegration of the implants. However, no information could be found about the efficiency of these approaches on Ti-6Al-4V alloy surfaces. This study examined the drug loading capacity of anodized nanotubular Ti-6Al-4V alloy surfaces in vitro as well as the bone response to surface immobilized bisphosphonates (BPs) on anodized nanotubular Ti-6Al-4V alloy surface in tibiae of rats. Ti-6Al-4V alloy titanium was divided into two groups: (1) control group (nontreated); (2) test group (anodized, heat-, and bisphosphonate-treated group). In vitro, amount of the drug released from the both groups' specimens was examined; all samples were 1 × 2 cm in size. In vivo, the 10 implants were placed inside of tibias of five rats. After 4 weeks, the bone response of the implants was evaluated using a removal torque test, and measuring bone contact and bone area. In addition, the surfaces of the extracted implants were observed by FE-SEM and EDS. In vitro, the drug loading capacity of the Ti-6Al-4V alloy surfaces was enhanced by anodizing surface modification. The values of the removal torque, bone contact, and bone area were significantly higher in the test group (p < 0.05). Furthermore, according to the EDS analysis, the amounts of Ca and P on the surface of the extracted implants were higher in the test group. Within the limits of this experiment, results of this research demonstrated that bisphosphonate-treated Ti-6Al-4V alloy implants with nanotubular surfaces have positive effects in bone-to-implant contact.

  18. Catalytic oxidation of volatile organic compounds (n-hexane, benzene, toluene, o-xylene promoted by cobalt catalysts supported on γ-Al2O3-CeO2

    Directory of Open Access Journals (Sweden)

    R. Balzer

    2014-09-01

    Full Text Available Cobalt catalysts supported on γ-alumina, ceria and γ-alumina-ceria, with 10 or 20%wt of cobalt load, prepared by the wet impregnation method and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, field emission transmission electron microscopy (FETEM, N2 adsorption-desorption isotherms (BET/BJH methods, energy-dispersive X-ray spectroscopy (EDX, X-ray photoemission spectroscopy (XPS, O2-chemisorption and temperature programmed reduction (TPR were used to promote the oxidation of volatile organic compounds (n-hexane, benzene, toluene and o-xylene. For a range of low temperatures (50-350 °C, the activity of the catalysts with a higher cobalt load (20% wt was greater than that of the catalysts with a lower cobalt load (10% wt. The Co/γ-Al2O3-CeO2 catalytic systems presented the best performances. The results obtained in the characterization suggest that the higher catalytic activity of the Co20/γ-Al2O3-CeO2 catalyst may be attributed to the higher metal content and amount of oxygen vacancies, as well as the effects of the interaction between the cobalt and the alumina and cerium oxides.

  19. Effect of MgO and Al2O3 on liquid phase formation in the sintering process of iron ore powder%MgO 和 Al2O3对铁矿粉烧结液相生成的影响

    Institute of Scientific and Technical Information of China (English)

    邓涛; 曹雪洋; 王建超

    2015-01-01

    为阐述烧结过程熔融机制和成矿机制,明确 MgO、Al2 O3质量分数对烧结液相生成和矿物组成的影响是至关重要的。利用 Factsage 软件计算 Fe2 O3-SiO2-CaO-Al2 O3-MgO 体系的液相生成,计算氧分压在500 Pa 时,不同温度,不同 MgO、Al2 O3质量分数下体系液相生成和液相区分布的影响。通过烧结试验,分析烧结矿的矿相和矿物成分,结合软件计算得出烧结矿中 MgO 质量分数为2.0%、Al2 O3质量分数为3.0%时其液相量、矿相、矿物成分达到最优适合烧结冶炼的标准。%To illustrate the melting mechanism and mineralization mechanism of sintering process.Making clear the influence of MgO and Al2 O3 content on sintering liquid phase formation and mineral composition is of vital impor-tance.Liquid phase formation of Fe2 O3-SiO2-CaO-Al2 O3-MgO system is calculated by Factsage software.As well as the effect of variation MgO and Al2 O3 content on liquid phase formation and distribution under different tempera-tures at oxygen partial pressure of 500 Pa.Through the sintering experiment,mineral phase and mineral composition of sinter ore are analyzed.The optimal sintering smelting standard for mass fraction of liquid phase,miner phase and mineral composition is concluded with the software calculation when the content of MgO and Al2 O3 is 2.0% and 3.0% in sinter respectively.

  20. Effect of oxidation on α″-Fe{sub 16}N{sub 2} phase formation from plasma-synthesized spherical core–shell α-Fe/Al{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zulhijah, Rizka [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Nandiyanto, Asep Bayu Dani [Departemen Kimia, Fakultas Pendidikan Matematika dan Ilmu Pengetahuan Alam, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudi No. 229, Bandung 40154 (Indonesia); Ogi, Takashi, E-mail: ogit@hiroshima-u.ac.jp [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Iwaki, Toru [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Nakamura, Keitaro [Research Center for Production and Technology, Nisshin Seifun Group, Inc., 5-3-1, Tsurugaoka, Fujimino, Saitama 356-8511 (Japan); Okuyama, Kikuo [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan)

    2015-05-01

    The introduction of an oxidation treatment to the synthesis of spherical and core–shell α″-Fe{sub 16}N{sub 2}/Al{sub 2}O{sub 3} nanoparticles (~62 nm) from plasma-synthesized core–shell α-Fe/Al{sub 2}O{sub 3} nanoparticles has been found to result in a high yield of α″-Fe{sub 16}N{sub 2} phase of up to 98%. The oxidation treatment leads the formation of a maghemite phase with open channeled structures along the c-axis, facilitating penetration of H{sub 2} and NH{sub 3} gases during the hydrogen reduction and nitridation steps. The saturation magnetization and magnetic coercivity of the core–shell α″-Fe{sub 16}N{sub 2}/Al{sub 2}O{sub 3} magnetic nanoparticles were found to be 156 emu/g and 1450 Oe, respectively. The detailed effects of the oxidation on the formation of α″-Fe{sub 16}N{sub 2} phase were investigated by characterizing the morphology (SEM, TEM and BET), elemental composition (EDX, EELS, and XAFS) and magnetic properties (Mössbauer and MSPS) of the prepared particles. The good magnetic properties obtained have the potential for future applications such as rare-earth-free magnetic materials. - Highlights: • High yield of α″-Fe{sub 16}N{sub 2} up to 98% was prepared from core–shell α-Fe/Al{sub 2}O{sub 3} NPs. • Introduction of oxidation improved yield of α″-Fe{sub 16}N{sub 2} for large size of NPs. • Oxidation forming microporous structured maghemite facilitated nitridation process. • Particle morphology changed during the nitrogen process due to atomic dislocation. • Core–shell α″-Fe{sub 16}N{sub 2}/Al{sub 2}O{sub 3} nanopa