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Sample records for als promote formation

  1. Cooperativity between Al Sites Promotes Hydrogen Transfer and Carbon-Carbon Bond Formation upon Dimethyl Ether Activation on Alumina.

    Science.gov (United States)

    Comas-Vives, Aleix; Valla, Maxence; Copéret, Christophe; Sautet, Philippe

    2015-09-23

    The methanol-to-olefin (MTO) process allows the conversion of methanol/dimethyl ether into olefins on acidic zeolites via the so-called hydrocarbon pool mechanism. However, the site and mechanism of formation of the first carbon-carbon bond are still a matter of debate. Here, we show that the Lewis acidic Al sites on the 110 facet of γ-Al2O3 can readily activate dimethyl ether to yield CH4, alkenes, and surface formate species according to spectroscopic studies combined with a computational approach. The carbon-carbon forming step as well as the formation of methane and surface formate involves a transient oxonium ion intermediate, generated by a hydrogen transfer between surface methoxy species and coordinated methanol on adjacent Al sites. These results indicate that extra framework Al centers in acidic zeolites, which are associated with alumina, can play a key role in the formation of the first carbon-carbon bond, the initiation step of the industrial MTO process. PMID:27162986

  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. 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.

  5. 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.

  6. The Al-Al3Ni Eutectic Reaction: Crystallography and Mechanism of Formation

    Science.gov (United States)

    Fan, Yangyang; Makhlouf, Makhlouf M.

    2015-09-01

    The characteristics of the Al-Al3Ni eutectic structure are examined with emphasis on its morphology and crystallography. Based on these examinations, the mechanism of formation of this technologically important eutectic is postulated. It is found that a thin shell of α-Al forms coherently around each Al3Ni fiber. The excellent thermal stability of the Al-Al3Ni eutectic may be attributed to the presence of this coherent layer.

  7. Effects of Al substitution on goethite formation

    OpenAIRE

    Premoli, Alessandra Maria; Melis, Pietro; Gessa, Carlo Emanuele; Deiana, Salvatore Andrea

    1984-01-01

    Goethites containing up to 32.7 mole % Al were synthesized and characterized through diffractometry, spectrometry, DSC and chemical techniques. Results indicate that crystal growth was favoured or hindered depending on the percentage of aluminum incorporated into the structure. Goethites to which 5-10 mole % Al were initially added crystallized best, as shown by the highest crystallite dimensions calculated from X-ray and Mössbauer analyses, and by the lowest surface areas values. Over suc...

  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. 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 ℃.

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

    International Nuclear Information System (INIS)

    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 Fe2Al5. • 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 Fe2Al5 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 Fe2Al5 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 Fe2Al5 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

  11. 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.

  12. Formation of Nb3Al in powder processed Nb-Al superconductors

    International Nuclear Information System (INIS)

    In high magnetic fields, the critical current density is strongly dependent on the upper critical field, which is determined primarily by the stoichiometry of the Nb3Al. The critical temperature (T/sub c/), like the upper critical field, is considered to be a measure of the ''intrinsic'' quality of the superconductor, indicating the stoichiometry, order, and strain. If the A15 phase is stoichiometric and well ordered, a high T/sub c/ (and high H/sub C2/) is expected, regardless of the volume fraction of superconductor. On the other hand, if sigma phase is present with the A15, the resultant composition gradient across the sigma-A15 interface(s) requires that some of the A15 be off-stoichiometric, and therefore that the T/sub c/ (and H/sub C2/) be low. Thus the extent of the A15 (Nb3Al) reaction and the quality of the A15 formed are interdependent. This work focuses on the factors that control the extent of Nb3Al formation in Nb/Al powder wires. The morphology and content of the reacted and unreacted wires are studied in optical, SEM, and TEM micrographs. Critical current density data and its dependence on processing are explained in terms of the unreacted microstructure and its effect on the extent of Nb3Al formation. As a method of improving the critical current density, a new variation of the conventional powder process for wire manufacturing is developed and tested

  13. 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.

  14. FORMATION AND FURTHER DEVELOPMENT OF MODERN PROMOTION OF PHARMACEUTICAL PRODUCTS

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    Юрий Владимирович Тарасов

    2014-02-01

    Full Text Available The articles addresses key notions and elements of marketing of pharmaceutical companies. Key stages and particularities of formation of pharmaceutical marketing are considered. It is proved that in general pharmaceutical market is developing under general marketing rules, however while developing strategy of promotion of pharmaceutical products specific features of the industry must be taken into consideration. The authors describes specific features of modern pharmaceutical market, which must be considered while developing policy of promotion of pharmaceutical products.The analysis is made of modern state of Russian pharmaceutical industry, its place in world pharmaceutical market. It is found that development of pharmaceutical market is directly influenced by the reform of pharmaceutical industry initiated by the Government of our country in 2008. Characteristic of current stage of market development is more strict conditions in marketing sphere and promotion of drugs. DOI: http://dx.doi.org/10.12731/2218-7405-2013-12-2

  15. 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.

  16. 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

  17. 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. PMID:24045646

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

    Science.gov (United States)

    Roudbarmohammadi, Shahla; Roudbary, Maryam; Bakhshi, Bita; Katiraee, Farzad; Mohammadi, Rasoul; Falahati, Mehraban

    2016-01-01

    Background: A cluster of genes are involved in the pathogenesis and adhesion of Candida albicans to mucosa and epithelial cells in the vagina, the important of which is agglutinin-like sequence (ALS) genes. As well as vaginitis is a significant health problem among women, the antifungal resistance of Candida species is continually increasing. This cross-sectional study investigates the expression of ALS1 and ALS3 genes and biofilm formation in C. albicans isolate isolated from vaginitis. Materials and Methods: Fifty-three recognized isolates of C. albicans were collected from women with recurrent vulvovaginal candidiasis in Iran, cultured on sabouraud dextrose agar, and then examined for gene expression. Total messenger RNA (mRNA) extracted from C. albicans isolates and complementary DNA synthesized using reverse transcriptase enzyme. Reverse transcription-polymerase chain reaction (RT-PCR) using specific primer was used to evaluate the expression of ALS1 and ALS3 through housekeeping (ACT1) genes. 3-(4,5-dimethyl-2-thiazyl)-2,5-diphenyl-2H-tetrazolium bromide assay was performed to assess adherence capacity and biofilm formation in the isolated. Results: Forty isolates (75.8%) expressed ALS1 and 41 isolates (77.7%) expressed ALS3 gene. Moreover, 39 isolates (74%) were positive for both ALS1 and ALS3 mRNA by the RT-PCR. Adherence capability in isolates with ALS1 or ALS3 genes expression was greater than the control group (with any gene expression), besides, it was significantly for the most in the isolates that expressed both ALS1 and ALS3 genes simultaneously. 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. PMID:27376044

  19. Promotion of follicular antrum formation by pig oocytes in vitro.

    Science.gov (United States)

    Shen, X; Miyano, T; Kato, S

    1998-02-01

    Pig oocyte-cumulus-granulosa cell complexes (OCG complexes) from pig early antral follicles reorganise an antrum under the stimulation of FSH. The purpose of this study was to examine the role of the oocytes in antrum formation. In the first experiment, oocyte-cumulus complexes were removed from pig OCG complexes, and the antrum formation of parietal granulosa cells themselves (PGs) was examined. Antrum formation by sham-operated OCG complexes (OC/G complexes), in which the connections between the oocytes-cumulus complexes and the parietal granulosa cells had been disrupted, was also examined. The complexes were cultured for 8 days in collagen gels in the presence of 10 ng/ml FSH. Antra were formed in about 60% of the intact OCG complexes and the sham-operated OCG complexes, while only 20% of the PGs formed antra. In the second experiment, oocyte-cumulus complexes in the OCG complexes were replaced by denuded oocytes (O/G complexes) or Sephadex G-25 beads (B/G complexes) similar in diameter to the oocytes, and the two types of complexes were cultured under the same conditions. The O/G complexes formed antra to a similar extent as the OC/G complexes, whereas the B/G complexes scarcely formed any antra. The histological sections showed that the granulosa cells in the OC/G and O/G complexes were in intimate contact with each other and retained a shape similar to those in the ovarian follicles, while the granulosa cells in the PGs and B/G complexes became quite irregular in shape. These results suggest that pig oocytes promote contact between the granulosa cells to induce antrum formation in a physiological manner. PMID:9652071

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

    International Nuclear Information System (INIS)

    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 each other. This

  1. 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

  2. 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.

  3. 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.

  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. Diatom assemblages promote ice formation in large lakes.

    Science.gov (United States)

    D'souza, N A; Kawarasaki, Y; Gantz, J D; Lee, R E; Beall, B F N; Shtarkman, Y M; Koçer, Z A; Rogers, S O; Wildschutte, H; Bullerjahn, G S; McKay, R M L

    2013-08-01

    We present evidence for the directed formation of ice by planktonic communities dominated by filamentous diatoms sampled from the ice-covered Laurentian Great Lakes. We hypothesize that ice formation promotes attachment of these non-motile phytoplankton to overlying ice, thereby maintaining a favorable position for the diatoms in the photic zone. However, it is unclear whether the diatoms themselves are responsible for ice nucleation. Scanning electron microscopy revealed associations of bacterial epiphytes with the dominant diatoms of the phytoplankton assemblage, and bacteria isolated from the phytoplankton showed elevated temperatures of crystallization (T(c)) as high as -3 °C. Ice nucleation-active bacteria were identified as belonging to the genus Pseudomonas, but we could not demonstrate that they were sufficiently abundant to incite the observed freezing. Regardless of the source of ice nucleation activity, the resulting production of frazil ice may provide a means for the diatoms to be recruited to the overlying lake ice, thereby increasing their fitness. Bacterial epiphytes are likewise expected to benefit from their association with the diatoms as recipients of organic carbon excreted by their hosts. This novel mechanism illuminates a previously undescribed stage of the life cycle of the meroplanktonic diatoms that bloom in Lake Erie and other Great Lakes during winter and offers a model relevant to aquatic ecosystems having seasonal ice cover around the world. PMID:23552624

  6. 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.

  7. Promotion effect of iron on Mo/Al2O3 catalyst for the CAMERE process

    Directory of Open Access Journals (Sweden)

    Abolfazl Gharibi Kharaji

    2012-08-01

    Full Text Available Reverse Water Gas Shift (RWGS reaction is one of the main reactions that can be used toreduce greenhouse gases emissions. Through this reaction CO2 is converted to CO to produce beneficialchemicals such as methanol. In this paper Mo-Al2O3 catalyst was prepared and then promoted with Feions through co-impregnation method to produce Fe-Mo-Al2O3 catalyst. XRD tests were taken todetermine the structure of the catalysts. Activity, selectivity and stability of both catalysts wereinvestigated in a batch reactor and the results indicate that addition of Fe promoter to Mo-Al2O3 catalystincreased its activity and CO selectivity. Fe-Mo-Al2O3 showed acceptable catalytic stability during RWGSreaction. As a whole, Fe-Mo-Al2O3 can be a suitable candidate for RWGS reaction in CAMERE (carbondioxide hydrogenation to form methanol via a reverse-water-gas-shift reaction process.

  8. Formation enthalpies of Al-Fe-Zr-Nd system calculated by using geometric and Miedema's models

    Science.gov (United States)

    Zhang, Lei; Wang, Rongcheng; Tao, Xiaoma; Guo, Hui; Chen, Hongmei; Ouyang, Yifang

    2015-04-01

    Formation enthalpy is important for the phase stability and amorphous forming ability of alloys. The formation enthalpies of Fe17RE2 (RE=Ce, Pr, Nd, Gd and Er) obtained by Miedema's theory are in good agreement with those of the experiments. The dependence of formation enthalpy on concentration of Al for intermetallic (AlxFe1-x)17Nd2 have been calculated by Miedema's theory and the geometric model. The solid solubility of Al in (AlxFe1-x)17Nd2 is coincident with the concentration dependence of formation enthalpy. The mixing enthalpies of liquid alloys and formation enthalpies of alloys for Al-Fe-Zr-Nd system have been predicted. The calculated mixing enthalpy indicates that the adding of Fe or Nd decreases monotonously the magnitude of enthalpy. The formation enthalpies of Al-Fe-Zr-Nd system indicate that the shape of the enthalpy contour map changes when the content of Al is less than 50.0 at% and then it remains unchanged except the decrease of magnitude. The formation enthalpy of Al-Fe-Zr-Nd increases with the increase of Fe and/or Nd content. The negative formation enthalpy indicates that Al-Fe-Zr-Nd system has higher amorphous forming ability and wide amorphous forming range. The certain contents of Zr and/or Al are beneficial for the formation of Al-Fe-Zr-Nd intermetallics.

  9. 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.

  10. 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.

  11. Formation of a novel ordered Ni3Al surface structure by codeposition on NiAl(110).

    Science.gov (United States)

    Han, Yong; Unal, Barış; Evans, J W

    2012-05-25

    The formation of a new type of ordered 2D Ni3Al overlayer by low-temperature codeposition on NiAl(110) is demonstrated by kinetic Monte Carlo simulation of a multisite atomistic lattice-gas model with a precise treatment of surface diffusion kinetics. Simultaneous codeposition with 3:1 Ni:Al yields poor ordering at 300 K but well-ordered structures by ~500 K. Sequential codeposition of Ni then Al yields unmixed core-ring nanostructures at 300 K but strong intermixing and ordering by ~500 K. PMID:23003283

  12. Carbon Monoxide Promotes Lateral Root Formation in Rapeseed

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Carbon monoxide (CO), an odorless, tasteless and colorless gas, has recently proved to be an important bioactive or signal molecule in mammalian cells, with its effects mediated mainly by nitric oxide (NO). In the present report, we show that exogenous CO induces lateral root (LR) formation, an NO-dependent process. Administration of the CO donor hematin to rapeseed (Brassica napus L. Yangyou 6) seedlings for 3 days, dose-dependently promoted the total length and number of LRs. These responses were also seen following the application of gaseous CO aqueous solutions of different saturated concentrations. Furthermore, the actions of CO on seedlings were fully reversed when the CO scavenger hemoglobin (Hb)or the CO-specific synthetic inhibitor zinc protoporphyrin-Ⅸ (ZnPPIX) were added. Interestingly, depletion of endogenous NO using its specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO)or the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME), led to the complete abolition of LR development, illustrating an important role for endogenous NO in the action of CO on LR formation. However, the or absence of ZnPPIX. Furthermore, using an anatomical approach combined with laser scanning confocal microscopy with the NO-specific fluorophore 4,5-diaminofluorescein diacetate, we observed that both hematin and SNP increased NO release compared with control samples and that the NO signal was mainly distributed in the LR primordia (LRP), especially after 36 h treatment. The LRP were found to have similar morphology in control, SNP- and hematin-treated seedlings.Similarly, the enhancement of the NO signal by CO at 36 h was differentially quenched by the addition of cPTIO, L-NAME,ZnPPIX and Hb. In contrast, the induction of NO caused by SNP was not affected by the application of ZnPPIX. Therefore,we further deduced that CO induces LR formation probably mediated by the NO/NOS pathway and NO may act

  13. 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.

  14. 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-%.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Local formation of a Heusler structure in CoFe-Al alloys

    Science.gov (United States)

    Wurmehl, S.; Jacobs, P. J.; Kohlhepp, J. T.; Swagten, H. J. M.; Koopmans, B.; Maat, S.; Carey, M. J.; Childress, J. R.

    2011-01-01

    We systematically study the changes in the local atomic environments of Co in CoFe-Al alloys as a function of Al content by means of nuclear magnetic resonance. We find that a Co2FeAl Heusler type structure is formed on a local scale. The observed formation of a highly spin-polarized Heusler compound may explain the improved magnetotransport properties in CoFe-Al based current-perpendicular-to-the-plane spin-valves.

  20. Formation of Small Blocky Al3Ti Particles via Direct Reaction Between Solid Ti Powders and Liquid Al

    Science.gov (United States)

    Liu, Z. W.; Han, Q.; Li, J. G.

    2012-12-01

    The evolution of titanium powders in the pure aluminum melt at a lower temperature was studied in our research. The process involved some titanium powders being added into the pure aluminum melt at 1003 K (730 °C), and then the melt was cast into an ingot after 5 minutes. A reaction layer composed of some loose Al3Ti particles was formed on the solid Ti surface due to the reactive diffusion between titanium and aluminum. In-situ blocky Al3Ti particles smaller than 5 μm were produced in the aluminum matrix. A reaction-peeling model was suggested to illustrate the formation mechanism of Al3Ti particles, and a simple approach for fabricating in-situ Al3Ti/Al-alloy composites was proposed as well.

  1. 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.

  2. Formation of (111) recrystallization texture in Al-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kamijo, T. [Yokohama Nat. Univ. (Japan). Dept. of Mech. Eng. and Mater. Sci.; Iwasaki, Y. [Yokohama Nat. Univ. (Japan). Dept. of Mech. Eng. and Mater. Sci.; Fukutomi, H. [Yokohama Nat. Univ. (Japan). Dept. of Mech. Eng. and Mater. Sci.

    1996-09-01

    Al-4.0Mg and Al-5.5Mg alloys were warm-rolled to 85% at the temperatures ranging from 523 K to 573 K. The (001)[110] shear texture was formed in the surface of the sheets rolled below 543 K. The (111)[ anti 110] or the (112)[ anti 110] shear texture with the spread around the rolling direction developed in the sheets rolled above 553 K. After annealing the complicated recrystallization texture containing the (111) component parallel to the rolling plane was generated in the sheets rolled above 553 K. Such recrystallization texture was penetrated deeper into the inward layer with an increase in rolling temperature. (orig.)

  3. 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

  4. Structure formation of AlMg2-AlN composite cast in electromagnetic field

    OpenAIRE

    M. Cholewa; M. Staszewski; M. Sozańska; B. Formanek

    2007-01-01

    Purpose: Basic material concept, technology and some results of studies on aluminum matrix composite with dispersive aluminum nitride reinforcement was shown. Studied composites were manufactured with use f ex-situ technique and powder metallurgy.Design/methodology/approach: Aluminum nitride powder was manufactured in process of self-evolving high-temperature synthesis SHS. Composite powder Al-AlN was obtained using mechanical alloying. Composite castings were manufactured in stir casting pro...

  5. FORMATION AND PROPERTIES OF MBE GROWN AlSb-GaSb (100) INTERFACES

    OpenAIRE

    Raisin, C.; Tegmousse, H.; Lassabatere, L.

    1987-01-01

    In this paper, we present results, we have obtained on GaSb-AlSb or AlSb-GaSb interfaces grown by MBE. We first focuss on the surface properties obtained by AES, R H E E D, work function topographies. Then, we describe the formation of the interface and the evolution of its properties during growth. We detail A E S and work function measurements and show Al migration at the GaSb/AlSb interface and no noticeable Ga diffusion at the AlSb/GaSb interface.

  6. Role of defect coordination environment on point defects formation energies in Ni-Al intermetallic alloys

    Science.gov (United States)

    Tennessen, Emrys; Rondinelli, James

    We present a relationship among the point defect formation energies and the bond strengths, lengths, and local coordination environment for Ni-Al intermetallic alloys based on density functional calculations, including Ni3Al, Ni5Al3, NiAl,Ni3Al4, Ni2Al3 and NiAl3. We find the energetic stability of vacancy and anti-site defects for the entire family can be attributed primarily to changes in interactions among first nearest neighbors, owing to spatially localized charge density reconstructions in the vicinity of the defect site. We also compare our interpretation of the local coordination environment with a DFT-based cluster expansion and discuss the performance of each approach in predicting defect stability in the Ni-Al system.

  7. Dynamical resonant electron capture in atom surface collisions: H- formation in H-Al(111) collisions

    Science.gov (United States)

    Borisov, A. G.; Teillet-Billy, D.; Gauyacq, J. P.

    1992-05-01

    The formation of H- ion by grazing-angle collisions of hydrogen on an Al(111) surface is investigated with the newly developed coupled angular mode method. The capture process involves a dynamical resonant process induced by the collision velocity. All the resonance properties of the H- level in front of an Al(111) surface are determined: position, width, and angular distribution of ejected electrons. The results are shown to account for the recent observations on H- formation by Wyputta, Zimny, and Winter.

  8. Microstructure and mechanical properties of hypereutectic Al-Fe alloys prepared by semi-solid formation

    Directory of Open Access Journals (Sweden)

    Liu Bo

    2011-11-01

    Full Text Available The effects of alloying elements, electromagnetic stirring, reheating and semi-solid formation on the microstructure and mechanical properties of Al-Fe alloys prepared by semi-solid formation were studied. It was found that alloying elements and electromagnetic stirring can alter the morphology and growth mode of the iron-rich phase in Al-Fe alloys; and effectively refine the primary Al3Fe phase. In contrast to the microstructure obtained in conventional casting, the Al3Fe phase becomes thin short rod-like instead of thick needle-like; and the dendritic grain structure almost disappears in the semi-solid formation. The Al3Fe phase can be further refined through being dissolved or fused during subsequent reheating. It was also found that the larger extrusion ratio of semi-solid formation causes a greater crushing effect and therefore the Al3Fe phase is more refined and has more uniform distribution. Moreover, Al-Fe alloys prepared by semi-solid formation exhibit excellent mechanical properties at both room and high temperatures.

  9. 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.

  10. Type IV pili promote early biofilm formation by Clostridium difficile.

    Science.gov (United States)

    Maldarelli, Grace A; Piepenbrink, Kurt H; Scott, Alison J; Freiberg, Jeffrey A; Song, Yang; Achermann, Yvonne; Ernst, Robert K; Shirtliff, Mark E; Sundberg, Eric J; Donnenberg, Michael S; von Rosenvinge, Erik C

    2016-08-01

    Increasing morbidity and mortality from Clostridium difficile infection (CDI) present an enormous challenge to healthcare systems. Clostridium difficile express type IV pili (T4P), but their function remains unclear. Many chronic and recurrent bacterial infections result from biofilms, surface-associated bacterial communities embedded in an extracellular matrix. CDI may be biofilm mediated; T4P are important for biofilm formation in a number of organisms. We evaluate the role of T4P in C. difficile biofilm formation using RNA sequencing, mutagenesis and complementation of the gene encoding the major pilin pilA1, and microscopy. RNA sequencing demonstrates that, in comparison to other growth phenotypes, C. difficile growing in a biofilm has a distinct RNA expression profile, with significant differences in T4P gene expression. Microscopy of T4P-expressing and T4P-deficient strains suggests that T4P play an important role in early biofilm formation. A non-piliated pilA1 mutant forms an initial biofilm of significantly reduced mass and thickness in comparison to the wild type. Complementation of the pilA1 mutant strain leads to formation of a biofilm which resembles the wild-type biofilm. These findings suggest that T4P play an important role in early biofilm formation. Novel strategies for confronting biofilm infections are emerging; our data suggest that similar strategies should be investigated in CDI. PMID:27369898

  11. On DABAL-Me₃ promoted formation of amides

    OpenAIRE

    Dubois, Nathalie; Glynn, Daniel; McInally, Thomas; Rhodes, Barrie; Woodward, Simon; Irvine, Derek; Dodds, Chris

    2013-01-01

    The range and utility of DABAL-Me3 couplings of methyl esters and free carboxylic acids with primary and secondary amines under a variety of conditions (reflux, sealed tube, microwave) has been compared for a significant range of coupling partners of relevance to the preparation of amides of interest in pharmaceutical chemistry. Commercial microwave reactors promote the fastest couplings and allow the use of significantly sterically hindered amines (primary and secondary) and carboxylic acids...

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

    International Nuclear Information System (INIS)

    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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. Reactive oxygen species promote raft formation in T lymphocytes.

    Science.gov (United States)

    Lu, Shu-Ping; Lin Feng, Ming-Hsien; Huang, Huey-Lan; Huang, Ya-Ching; Tsou, Wen-I; Lai, Ming-Zong

    2007-04-01

    Lipid rafts are involved in many cell biology events, yet the molecular mechanisms on how rafts are formed are poorly understood. In this study we probed the possible requirement of reactive oxygen species (ROS) for T-cell receptor (TCR)-induced lipid raft formation. Microscopy and biochemical analyses illustrated that blockage of ROS production, by superoxide dismutase-mimic MnTBAP, significantly reduced partitioning of LAT, phospho-LAT, and PLC-gamma in lipid rafts. Another antioxidant N-acetylcysteine (NAC) displayed a similar suppressive effect on the entry of phospho-LAT into raft microdomains. The involvement of ROS in TCR-mediated raft assembly was observed in T-cell hybridomas, T leukemia cells, and normal T cells. Removal of ROS was accompanied by an attenuated activation of LAT and PKCtheta, with reduced production of IL-2. Consistently, treating T cells with the ROS-producer tert-butyl hydrogen peroxide (TBHP) greatly enhanced membrane raft formation, distribution of phospho-LAT into lipid rafts, and increased IL-2 production. Our results indicate for the first time that ROS contribute to TCR-induced membrane raft formation. PMID:17349922

  20. 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.

  1. 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

  2. Dexamethasone down-regulates, the activity of promoter from human al (Ⅱ) procollagen gene

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To investigate the effects of dexamethasone on the promoter activity of human al(1) procollagen gene.Methods Fibroblasts from human skin were primary cultured and subcultured. (1) The effects of dexamethasone on the human skin fibroblasts were determined by BrdU incorporation into DNA of fibroblasts. (2) Three plasmids containing various engths of 5' flanksequence of human al(1) procollagen gene and CAT as reporter gene were constructed, and were transfected into the human skin fi-broblasts by FuGENE Transfecfion Reagent. The effects of dexamethasone on 3 plasmids were determined by CAT - ELlSA. Results (1)After 24h of treatment on the fibroblasts with 110-9 ~110-4mol/L examethasone in DMEM containing 2% or 10% FCS, BrdU in-corporation into DNA showed no difference ( P > 0.05) . (2) the 3 plasmids were transfected into fibroblasts and then treated with 110-5mol/L and 110-6mol/L dexamethasones for 24h, relative CAT values were different belwent dexamethasone and control,higher dexamethasone(110 -5mol/L} and lower examethasone(110 -6mol/L) ( P <0. 05) . ConcluSion Dexamethasone has noeffects on the proliferation of human skin fibroblasts, and it has negative effect on the promoter activity of human al(1) procollagengene, which is dose- dependent.

  3. Electrochemical formation of Sc-Al intermetallic compounds in the eutectic LiCl-KCl. Determination of thermodynamic properties

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The formation mechanism of AlxScy intermetallic compounds was studied in the eutectic LiCl-KCl • The formation energy, global and consecutive formation constants of AlxScy were estimated from OCP. • XRD after potentiostatic electrolysis, allowed the identification of Al3Sc and Al2Sc • XRD after intermittent galvanostatic electrolysis allowed the identification of Al3Sc, Al2Sc and AlSc2 • SEM with EDX, allowed the identification of Al3Sc, Al2Sc, AlSc and AlSc2. - Abstract: The electrochemical formation of Sc-Al alloys was investigated in the eutectic LiCl-KCl by cyclic voltammetry and open circuit chronopotentiometry. On reactive Al electrode the electrochemical reduction of Sc(III) was observed at less cathodic potential values than at the surface of an inert W electrode, the potential shift is caused by the decrease of Sc activity in the metal phase due to the formation of Sc-Al intermetallic compounds at the interface. The formation mechanism of the intermetallic compounds was studied in a melt containing: (i) both Sc(III) and Al(III) ions, using a W electrode, and ii) Sc(III) ions using an Al electrode. Analysis of the samples after electrolysis runs by X-ray diffraction allowed the identification of Al3Sc and Al2Sc, whereas analysis by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), allowed the identification of Al3Sc, Al2Sc, AlSc and AlSc2. The formation energy of each AlxScy intermetallic compound, and the global and stepwise formation constant were estimated from open circuit chronopotentiometry measurements in the eutectic LiCl-KCl at 723 and 773 K using Al as working electrode

  4. 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 ...

  5. 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.

  6. Aurora A, MCAK, and Kif18b promote Eg5-independent spindle formation

    NARCIS (Netherlands)

    van Heesbeen, Roy G H P; Raaijmakers, Jonne A; Tanenbaum, Marvin E; Halim, Vincentius A; Lelieveld, Daphne; Lieftink, Cor; Heck, Albert J R; Egan, David A; Medema, René H

    2016-01-01

    Inhibition of the microtubule (MT) motor protein Eg5 results in a mitotic arrest due to the formation of monopolar spindles, making Eg5 an attractive target for anti-cancer therapies. However, Eg5-independent pathways for bipolar spindle formation exist, which might promote resistance to treatment w

  7. RNA-binding IMPs promote cell adhesion and invadopodia formation

    DEFF Research Database (Denmark)

    Vikesaa, Jonas; Hansen, Thomas V O; Jønson, Lars;

    2006-01-01

    Oncofetal RNA-binding IMPs have been implicated in mRNA localization, nuclear export, turnover and translational control. To depict the cellular actions of IMPs, we performed a loss-of-function analysis, which showed that IMPs are necessary for proper cell adhesion, cytoplasmic spreading...... and invadopodia formation. Loss of IMPs was associated with a coordinate downregulation of mRNAs encoding extracellular matrix and adhesion proteins. The transcripts were present in IMP RNP granules, implying that IMPs were directly involved in the post-transcriptional control of the transcripts. In particular......, we show that a 5.0 kb CD44 mRNA contained multiple IMP-binding sites in its 3'UTR, and following IMP depletion this species became unstable. Direct knockdown of the CD44 transcript mimicked the effect of IMPs on invadopodia, and we infer that CD44 mRNA stabilization may be involved in IMP...

  8. Crack Formation in Powder Metallurgy Carbon Nanotube (CNT)/Al Composites During Post Heat-Treatment

    Science.gov (United States)

    Chen, Biao; Imai, Hisashi; Li, Shufeng; Jia, Lei; Umeda, Junko; Kondoh, Katsuyoshi

    2015-12-01

    After the post heat-treatment (PHT) process of powder metallurgy carbon nanotubes (CNT)/Al composites, micro-cracks were observed in the composites, leading to greatly degraded mechanical properties. To understand and suppress the crack formation, an in situ observation of CNT/Al composites was performed at elevated temperatures. PHT was also applied to various bulk pure Al and CNT/Al composites fabricated under different processes. It was observed that the composites consolidated by hot-extrusion might form micro-cracks, but those consolidated by spark plasma sintering (SPS) showed no crack after PHT. A high-temperature SPS process before hot-extrusion was effective to prevent crack formation. The release of residual stress in severe plastic deformed (SPD) materials was responsible for the cracking phenomena during the PHT process. Furthermore, a good particle bonding was essential and effective to suppress cracks for SPD materials in the PHT process.

  9. Insight into the mechanism of Sb promoted Cu(In,Ga)Se2 formation

    International Nuclear Information System (INIS)

    Sb-doping has been demonstrated to be a new approach to promote Cu(In,Ga)Se2 (CIGS) thin film formation. To study the mechanism of Sb-promoted CIGS formation, we investigated the influence of Sb on the evolution of the critical intermediate Cu–Se phases, and found that Cu3SbSe3 species was formed. Phase change of the as-prepared Cu–Se compounds at elevated temperature was determined using the differential scanning calorimetry analysis. For samples containing Sb, the melting decomposition occurred at 507.1 °C, along with aggregation of nanocrystals into a bulk, while the morphology of the sample without Sb barely changed after heating. This result suggests that the mobile Cu3SbSe3 is likely the key intermediate responsible for Sb-promoted CIGS formation. Furthermore, we extended the scope of Sb-doping approach to solvothermal synthesis and CIGS nanocrystals were synthesized with significantly promoted kinetics in the presence of Sb. Based on these results, we propose the mechanism of Sb promoted CIGS formation. - Graphical abstract: Cu3SbSe3 mobile phase is likely the key species to promote the formation of Cu(In,Ga)Se2, and significantly promoting effect by Sb is also found in the synthesis of Cu(In,Ga)Se2 nanocrystals. Highlights: • In the presence of Sb, Cu3SbSe3 is formed while synthesizing the essential intermediate Cu–Se compounds for Cu(In,Ga)Se2 materials. • Cu3SbSe3 shows high mobility at elevated temperature. • Cu3SbSe3 mobile phase is likely the key species to improve Cu(In,Ga)Se2 thin film formation. • A synthesis methodology is developed to produce Cu(In,Ga)Se2 nanocrystals with significantly promoted reaction kinetics

  10. 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.

  11. 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.

  12. 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.

  13. Cambrian small shelly fossils from the Çal Tepe Formation, Taurus Mountains, Turkey

    OpenAIRE

    Sarmiento, Graciela N.; Fernández Remolar, David Carlos; Göncüoglu, M. Cemal

    2001-01-01

    [EN] Lower and Middle Cambrian carbonate rocks of the Çal Tepe Formation, cropping out in the western Taurus Mountains, yielded a large number of microfossil remains. Small shelly fossils from a single level in the upper Lower Cambrian represent a high diversity biota that could be related to the «Cambrian explosion». Microfossil association from the lower Middle Cambrian sediments of the Çal Tepe Formation is taxonomically very reduced and a dominant taxon is Hadimopanella GEDIK. Th...

  14. Cambrian small shelly fossils from the Çal Tepe Formation, Taurus Mountains, Turkey

    OpenAIRE

    Sarmiento, Graciela; Fernández Remolar, David Carlos; Göncüoglu, M. Cemal

    2001-01-01

    Lower and Middle Cambrian carbonate rocks of the Çal Tepe Formation, cropping out in the western Taurus Mountains, yielded a large number of microfossil remains. Small shelly fossils from a single level in the upper Lower Cambrian represent a high diversity biota that could be related to the «Cambrian explosion». Microfossil association from the lower Middle Cambrian sediments of the Çal Tepe Formation is taxonomically very reduced and a dominant taxon is Hadimopanella GEDIK. This sudden chan...

  15. 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.

  16. 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.

  17. 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......-molecule fluorescence insitu hybridization measurements show that heavy chromatin formation correlates with an unusually high firing pace of the promoter with more than 20 transcription events per minute. Heavy chromatin formation closely follows the modulation of promoter firing and strongly correlates with polymerase...

  18. 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

    2016-06-01

    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.

  19. Microstructure formation in binary Al-TM alloys under non-equilibrium solidification

    Energy Technology Data Exchange (ETDEWEB)

    Beresina, A L; Kurdyumov, G V [Institute for Metal Physics, 36, Vernadsky Blvd, Kyiv-142 (Ukraine); Segida, E A, E-mail: slena54@yahoo.co

    2009-01-01

    The structure formation in hypereutectic Al-Sc and hyperperitectic Al-Zr, Al-Hf alloys with concentration of alloying element up to 1.3 at.% have been studied under conditions far from thermodynamical equilibrium depending on cooling rate and quenching temperature. The co-operative growth structures are solidified with cooling rate of 10{sup 2}-10{sup 3} K/s regardless of overheating and under cooling rate of 10{sup 5}-10{sup 6} K/s at small overheating. The phase compound of these structures is alpha-solid solutions and phase with L1{sub 2}-ordered structure or two solid solutions with different concentrations of alloying element. The large overheating leads to formation of alpha-solid solution anomalously supersaturated under cooling rate of 10{sup 5}-10{sup 6} K/s.

  20. Formation of intermetallic phases on 55 wt.%Al-Zn-Si hot dip strip

    International Nuclear Information System (INIS)

    A study has been conducted to probe the formation of intermetallic phases on steel substrates immersed in 55 wt.%Al-Zn-Si hot dip baths as a function of dipping time and bath silicon content. Two bath compositions containing 1.3 and 1.5 wt.% Si, respectively, combined with two immersion times of 3 and 9 s were studied. It was found that the reaction rate and intermetallic phase formation varied in response to silicon content. Optical microscopy revealed a quantifiable difference in the development of the reaction layer between the two bath compositions. SEM-EDS revealed that the reaction layer that evolved on samples dipped in the 1.5 wt.% silicon bath were comprised of two intermetallic species, α-AlFeSi/Fe2Al5, whilst in the 1.3 wt.% bath there were three clearly identifiable intermetallic species α-AlFeSi/FeAl3/Fe2Al5. A fourth phase appeared to be present in samples immersed in the 1.3 wt.% Si bath that, due to its fine structure, could not be conclusively identified. Experimental results from the literature and from this study have been assessed with reference to the phase stability predicted by MTDATA, a thermodynamic modelling package

  1. The formation and crystallization for amorphous AlFeZr{sub 4} prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Chen Hongmei, E-mail: chenhm@gxu.edu.c [Key Laboratory of New Processing Technology for Nonferrous Metals and Materials of Ministry of Education, Department of Physics, Guangxi University, Nanning 530004 (China); Ouyang Yifang [Key Laboratory of New Processing Technology for Nonferrous Metals and Materials of Ministry of Education, Department of Physics, Guangxi University, Nanning 530004 (China); Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics, Hunan Normal University, Changsha 410081 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Guo Debo [Key Laboratory of New Processing Technology for Nonferrous Metals and Materials of Ministry of Education, Department of Physics, Guangxi University, Nanning 530004 (China); Liao Shuzhi [Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics, Hunan Normal University, Changsha 410081 (China); Zhong Xiaping [Key Laboratory of New Processing Technology for Nonferrous Metals and Materials of Ministry of Education, Department of Physics, Guangxi University, Nanning 530004 (China); Du Yong; Liu Yong [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

    2010-04-15

    Amorphous AlFeZr{sub 4} alloy has been prepared from elemental mixture powders by mechanical alloying. The microstructure, thermal stability and morphology of as-milled mixture powders were analyzed by XRD and DTA respectively. Two sequential exothermal peaks exist during the procedure of crystallization. The effective activation energies for crystallization were evaluated according to Kissinger's plot. The crystallization products of as-milled powders annealed at temperature over the crystallization temperature were studied, and the structural characteristic analysis of annealed sample was performed in an X-ray diffractometer. The crystallized phases are composed of FeZr{sub 2}, AlZr{sub 2} and AlFeZr intermetallic compounds. The formation enthalpies for FeZr{sub 2}, AlZr{sub 2} and AlFeZr are calculated from first-principles and Miedema's theory. Based on the calculated formation enthalpies, the products of crystallization for amorphous AlFeZr{sub 4} alloy are explained from thermodynamic point of view.

  2. 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.

  3. 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.

  4. Effect of total aluminum concentration on the formation and transformation of nanosized Al13 and Al30 in hydrolytic polymeric aluminum aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhaoyang; LIU Changjun; LUAN Zhaokun; ZHANG Zhongguo; LI Yanzhong; JIA Zhiping

    2005-01-01

    Influence of total aluminum concentration (CAlT) on the generation and transformation of nanosized Al13 and Al30 in hydrolytic polyaluminum aqueous solutions was investigated using high field 27Al NMR and time-developed Al-Ferron complex colorimetry. When prepared at the optimal basicity (B) of Al13 generation and 80℃, the Al13 species in polyaluminum solution tends to further polymerize and convert to Al30 and higher polymers when CAlT >0.2 mol·L-1, but Al13 does not convert to Al30 quantificationally, as the formation of Alu from Al13 and Al30 is accelerated in the same way. The conversion rate of Al13 is accelerated by the increase in CAlT. When CAlT >0.75 mol·L-1, Al13 content decreases rapidly, and Al30 content increases continuously and becomes the dominant nanometer polynuclear aluminum species. Alm is one of prerequisites of Al13 conversion to Al30. When CAlT increases and B reduces, the polymerization rate between Al13 and Alm increases, and at the same time, the dissociation reaction rate of Al13 and Al30 by H+ also increases. The latter becomes the dominant reaction in polyaluminum solution with low B value, so Al30 decreases with the increasing CAlT. The hydrolytic polyaluminum solution with Al13 content beyond 80% can only be prepared under the condition of CAlT<0.5 mol·L-1 and optimal B value.

  5. 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.

  6. Formation of CuAlO2 Film by Ultrasonic Spray Pyrolysis

    International Nuclear Information System (INIS)

    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 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 CuAlO2.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Influence of Al, Ti, V and O on acicular ferrite formation in TIG weld metal

    Energy Technology Data Exchange (ETDEWEB)

    Abson, D.J.; Francis-Scrutton, N. [TWI, Cambridge (United Kingdom). Materials Dept.

    1996-12-01

    An investigation has been carried out on the influence of Al, Ti and oxygen on the microstructure of TIG weld metal. In the first phase of the investigation, commercial C-Mn and C-Mn-Ni solid, flux-cored and metal-cored electrode wires, some of which contained Ti, were deposited by the hot wire TIGF process in preparations in C-Mn steel plates of two different Al levels. In the second phase, Al and Ti, both separately and together, were sputtered on to a C-Mn steel plate with a low Al level, and bead-on-plate cold wire TIG welds were produced, using a C-Mn wire, also with a low Al level. Metallographic examination of sectioned welds revealed that microstructures containing substantial amounts of fine-grained acicular ferrite were produced only where Al levels were not greatly in excess of the oxygen levels. The use of metal-cored wires increased weld oxygen levels up to {approximately}0.02%, and thus comparable levels of Al could be tolerated. In the cold wire TIG welds, where oxygen levels were {le}0.0043%, Al levels >0.005% reduced the proportion of acicular ferrite. At oxygen levels of {approximately}0.02%, in the hot wire TIG welds, a small amount of Ti ({approximately}0.005%) increased the proportion of acicular ferrite, but larger additions reduced it. At lower oxygen levels, in the cold wire TIG deposits, Ti additions {ge}0.024% reduced the proportion of acicular ferrite; however, for Al > 0.01%, Ti additions contributed to the formation of an increasing proportion of ferrite with second phase in the form of small colonies. In weld beads containing {approximately}0.02% oxygen, {approximately}0.04% V, diluted in from one of the parent steels, increased the proportion of acicular ferrite.

  13. 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.

  14. 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.)

  15. 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.

  16. Formation of Ag/Al Screen-Printing Contacts on B Emitters

    OpenAIRE

    Fritz, Susanne; König, Markus; Riegel, Stefanie; Herguth, Axel; Hörteis, Matthias; Hahn, Giso

    2015-01-01

    In this study, the contact formation process of Al containing Ag screen-printing pastes to BBr3-based B emitters on Si is investigated. Therefore, a detailed scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy study of top-view and cross-sectional samples was conducted. The possible influence of a SiN∞:H antireflection coating was considered by comparing contacts with and without a SiN∞:H layer. To analyze the role of the glass frit in the paste, the contact formation ...

  17. 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.

  18. 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.

  19. Impact of Ti/Al atomic ratio on the formation mechanism of non-recessed Au-free Ohmic contacts on AlGaN/GaN heterostructures

    Science.gov (United States)

    Constant, A.; Baele, J.; Coppens, P.; Qin, W.; Ziad, H.; De Backer, E.; Moens, P.; Tack, M.

    2016-09-01

    The formation mechanism of non-recessed Au-free Ohmic contacts on the AlGaN/GaN heterostructures is investigated for various Ti/Al atomic ratios (Al-rich versus Ti-rich) and annealing temperatures ranging from 500 to 950 °C. It is shown that Ti/Al atomic ratio is the key parameter defining the optimum annealing temperature for Ohmic contact formation. Ti-rich contacts processed at high temperature result in low contact resistance ˜0.7 Ω mm, better to those obtained at low temperature or with Al-rich metal stacks. The variation of the contact resistance with Ti/Al atomic ratio and annealing temperature is correlated with the intermetallic phase changes and interfacial reaction. Depending on the Ti/Al atomic ratio, two distinct mechanisms can be distinguished. For a small quantity of Ti (e.g., Al-rich contacts), Ohmic contact formation is done through a weak interfacial reaction which is nonexistent at high temperature due to the degradation of the metal morphology. However, for a quantity of Ti higher than 25 at. % (e.g., Ti-rich contacts), the agglomeration is delayed by 200 °C as compared to Al-rich contacts, and optimal contacts are formed at high temperature through a strong interfacial reaction.

  20. 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.

  1. Thyroid dysfunction, either hyper or hypothyroidism, promotes gallstone formation by different mechanisms*

    Science.gov (United States)

    Wang, Yong; Yu, Xing; Zhao, Qun-zi; Zheng, Shu; Qing, Wen-jie; Miao, Chun-di; Sanjay, Jaiswal

    2016-01-01

    We have investigated comprehensively the effects of thyroid function on gallstone formation in a mouse model. Gonadectomized gallstone-susceptible male C57BL/6 mice were randomly distributed into three groups each of which received an intervention to induce hyperthyroidism, hypothyroidism, or euthyroidism. After 5 weeks of feeding a lithogenic diet of 15% (w/w) butter fat, 1% (w/w) cholesterol, and 0.5% (w/w) cholic acid, mice were killed for further experiments. The incidence of cholesterol monohydrate crystal formation was 100% in mice with hyperthyroidism, 83% in hypothyroidism, and 33% in euthyroidism, the differences being statistically significant. Among the hepatic lithogenic genes, Trβ was found to be up-regulated and Rxr down-regulated in the mice with hypothyroidism. In contrast, Lxrα, Rxr, and Cyp7α1 were up-regulated and Fxr down-regulated in the mice with hyperthyroidism. In conclusion, thyroid dysfunction, either hyperthyroidism or hypothyroidism, promotes the formation of cholesterol gallstones in C57BL/6 mice. Gene expression differences suggest that thyroid hormone disturbance leads to gallstone formation in different ways. Hyperthyroidism induces cholesterol gallstone formation by regulating expression of the hepatic nuclear receptor genes such as Lxrα and Rxr, which are significant in cholesterol metabolism pathways. However, hypothyroidism induces cholesterol gallstone formation by promoting cholesterol biosynthesis. PMID:27381728

  2. 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.

  3. Investigation of the formation of quasicrystalline Al70-Pd20-Re10 phase in situ during annealing

    International Nuclear Information System (INIS)

    The change in the phase composition of thin-film layered AlPdRe nanostructures during annealing, which led to the formation of a quasicrystalline layer, has been studied in situ. It is shown that the Al3Pd phase is formed at a temperature above 260°C, which transforms into the AlPd phase at 580°C, and the icosahedral quasicrystalline Al-Pd-Re phase is formed at 680°C.

  4. 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. PMID:27502022

  5. Formation of a Novel Ordered Ni3Al Surface Structure by Codeposition on NiAl(110)

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yong [Iowa State Univ., Ames, IA (United States); Unal, Baris [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ames Laboratory (AMES), Ames, IA (United States); Evans, James W [Ames Laboratory (AMES), Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

    2012-05-23

    The formation of a new type of ordered 2D Ni3Al overlayer by low-temperature codeposition on NiAl(110) is demonstrated by kinetic Monte Carlo simulation of a multisite atomistic lattice-gas model with a precise treatment of surface diffusion kinetics. Simultaneous codeposition with 3:1 Ni:Al yields poor ordering at 300 K but well-ordered structures by ~500 K. Sequential codeposition of Ni then Al yields unmixed core-ring nanostructures at 300 K but strong intermixing and ordering by ~500 K.

  6. Triplex formation by morpholino oligodeoxyribonucleotides in the HER-2/neu promoter requires the pyrimidine motif

    OpenAIRE

    Basye, Jenny; Trent, John O.; Gao, Daquan; Ebbinghaus, Scot W.

    2001-01-01

    Triplex-forming oligonucleotides (TFOs) are good candidates to be used as site-specific DNA-binding agents. Two obstacles encountered with TFOs are susceptibility to nuclease activity and a requirement for magnesium for triplex formation. Morpholino oligonucleotides were shown in one study to form triplexes in the absence of magnesium. In the current study, we have compared phosphodiester and morpholino oligonucleotides targeting a homopurine–homopyrimidine region in the human HER2/neu promot...

  7. Formation of multilayered scale during the oxidation of NiAl-Mo alloy

    Science.gov (United States)

    Ray, P. K.; Akinc, M.; Kramer, M. J.

    2014-05-01

    We have studied the oxidation behavior of a hypereutectic NiAl-Mo alloy. This alloy showed an initial rapid mass loss followed by a relatively steady state behavior. The oxide scale formed during the oxidation process was seen to have a multilayered structure comprising of NiO, NiAl2O4, NiMoO4 and Al2O3 with minor amounts of MoO2 in the sub-scale region. The oxidation behavior is influenced significantly by the formation and stability of the constituent oxides, especially NiMoO4. Hence the decomposition behavior of NiMoO4 in the 1100-1200 °C was studied as well. The thermal decomposition of the NiMoO4 was slow at 1100 °C, but accelerated at 1200 °C, resulting in the formation of NiO, which remained in the oxide scale, and MoO3, which volatilized away.

  8. A unified approach for description of gas hydrate formation kinetics in the presence of kinetic promoters in gas hydrate converters

    International Nuclear Information System (INIS)

    Highlights: • A unified kinetic model for description of promoted and non-promoted gas hydrate formation processes is presented. • Effects of impeller speed, promoter concentration and different kinetic promoters are investigated. • A unique region of gas hydrate formation is identified regarding gas hydrate formation processes. • The proposed model is useful for understanding the behavior of gas hydrate formation processes and design of GTH converters. - Abstract: The kinetic promoters have found wide applications in enhancing the rate of energy conversion and storage via gas hydrate formation processes. Effects of different kinetic promoters such as anionic surfactants sodium dodecyl sulfate (SDS), dodecylbenzene sulfonic acid (DBSA), and sodium dodecyl benzene sulfonate (SDBS); cationic surfactants, Cetyl trimethyl ammonium bromide (CTAB), dodecyl trimethyl ammonium bromide (DTAB) and non-ionic surfactants, alkylpolyglucoside (APG), dodecyl polysaccharide glycoside (DPG), TritonX-100 (TX100) on methane (CH4), ethane (C2H6) and propane (C3H8) gas hydrate formation processes are investigated in this work. A macroscopic kinetic model based on the time variations of reaction chemical potential is also presented for global description of gas hydrate formation processes. Experimental gas hydrate formation data are employed to validate the proposed kinetic model. Effects of promoter’s concentrations and agitation intensities on the gas consumption profiles are also investigated. A universal correlation and a unified kinetic map have been proposed for macroscopic description of gas hydrate formation kinetics in the presence or absence of kinetic promoters. According to the presented unified kinetic map, a unique region of gas hydrate formation is identified for the first time. For negligible amounts of kinetic promoters, the presented region disappears and approaches to a unique path at high agitation intensities. The presented unified approach is very useful

  9. Enthalpies of formation of CaAl4O7 and CaAl12O19 (hibonite) by high temperature, alkali borate solution calorimetry

    Science.gov (United States)

    Geiger, C. A.; Kleppa, O. J.; Grossman, L.; Mysen, B. O.; Lattimer, J. M.

    1988-01-01

    Enthalpies of formation were determined for two calcium aluminate phases, CaAl4O7 and CaAl12O19, using high-temperature alkali borate solution calorimetry. The aluminates were synthesized by multiple-cycle heating and grinding stoichiometric mixtures of CaCO3 and Al2O3, and the products were characteized by X-ray diffraction and SEM microbeam analysis. The data on impurities (CaAl4O7 was found to be about 89.00 percent pure by weight and the CaAl12O19 samples about 91.48 percent pure) were used to correct the heat of solution values of the synthetic products. The enthalpies of formation, at 1063 K, from oxides, were found to be equal to -(25.6 + or - 4.7) kJ/g.f.w. for CaAl4O7 and -(33.0 + or - 9.7) kJ/g.f.w. for CaAl12O19; the respective standard enthalpies of formation from elements, at 298 K, were estimated to be -4007 + or - 5.2 kJ/g.f.w. and -10,722 + or - 12 kJ/g.f.w.

  10. The formation mechanism of eutectic microstructures in NiAl-Cr composites.

    Science.gov (United States)

    Tang, Bin; Cogswell, Daniel A; Xu, Guanglong; Milenkovic, Srdjan; Cui, Yuwen

    2016-07-20

    NiAl-based eutectic alloys, consisting of an ordered bcc matrix (B2) and disordered bcc fibers (A2), have been a subject of intensive efforts aimed at tailoring the properties of many of the currently used nickel-based superalloys. A thermodynamic phase field model was developed on a thermodynamic foundation and fully integrated with a thermo-kinetic database of the Ni-Al-Cr ternary system to elucidate the resulting peculiar eutectic microstructure. Invoking a variation of the liquid/solid interfacial thickness with temperature, we simulated the characteristic sunflower-like eutectic microstructures in the NiAl-Cr composites, consistent with experimental observations. The mechanism that governs the formation of the peculiar eutectic morphology was envisioned from the modeled evolutions associated with six sequential steps. Our calculations show that the conditional spinodal decomposition occurring in sequence could further trim and revise the microstructure of the eutectics by generating fine-domain structures, thereby providing an additional method to explore the novel NiAl-based eutectic composites with tunable properties at elevated temperatures. PMID:27385194

  11. Oxide film defects in Al alloys and the formation of hydrogen- related porosity

    Science.gov (United States)

    Griffiths, W. D.; Gerrard, A. J.; Yue, Y.

    2016-03-01

    Double oxide film defects have also been held responsible for the origins of hydrogen porosity, where hydrogen dissolved in the Al melt passes into the interior atmosphere of the double oxide film defect causing it to inflate. However, this is in opposition to long- established evidence that H cannot readily diffuse through aluminium oxide. To investigate this further, samples of commercial purity Al were first degassed to remove their initial H content, and then heated to above their melting point and held in atmospheres of air and nitrogen respectively, to determine any differences in H pick-up. The experiment showed that samples held in an oxidising atmosphere, and having an oxide skin, picked up significantly less H than when the samples were held in a nitrogen atmosphere, which resulted in the formation of AlN in cracks in the oxide skin of the sample. It is suggested that double oxide film defects can give rise to hydrogen-related porosity, but this occurs more quickly when the oxygen in the original oxide film defect has been consumed by reaction with the surrounding melt and nitrogen reacts to form AlN, which is more permeable to H than alumina, more easily allowing the oxide film defect to give rise to a hydrogen pore. This is used to interpret results from an earlier synchrotron experiment, in which a small pore was seen to grow into a larger pore, while an adjacent large pore remained at a constant size.

  12. Interface microstructure and formation mechanism of diffusion-bonded joints of TiAl to steel 40Cr

    Institute of Scientific and Technical Information of China (English)

    何鹏; 冯吉才; 张炳刚; 钱乙余

    2002-01-01

    TiAl intermetallics was diffusion bonded to steel 40Cr in vacuum furnace. The results show that at the TiAl-40Cr interface the mixture reaction layer of Ti3Al+FeAl+FeAl2 is formed close to the TiAl base, TiC layer is formed in the middle and obvious decarbonized layer is formed closest to the steel 40Cr side. The whole reaction process can be divided into three stages. In the first stage, TiC layer is formed at the interface TiAl/40Cr, as well, decarbonized layer occurs on the steel 40Cr side. In the second stage, TiAl, FeAl2 and FeAl are formed adjacent to TiAl, in the mean, the continuous diffusion of Al atoms from TiAl to 40Cr gives rise to the formation of Ti3Al. In the last stage, the thickness of each reaction layer increases with bonding time according to a parabolic law. The growth energy Q and the growth velocity K0 of reaction layer Ti3Al+FeAl+FeAl2+TiC in the diffusion-bonded joints of the TiAl base alloy to steel 40Cr are 203.017kJ/mol and 6.074mm2/s, respectively, and the growth formula (thickness of reaction layer) is y2=6.074×10-6exp(-203017.48/RT)t. By virtue of this formula, the growth of reaction layer Ti3Al+FeAl+FeAl2+TiC can be presetted and controlled.

  13. Mechanism of weld formation during very-high-power ultrasonic additive manufacturing of Al alloy 6061

    International Nuclear Information System (INIS)

    The microstructures of Al alloy 6061 subjected to very-high-power ultrasonic additive manufacturing were systematically examined to understand the underlying ultrasonic welding mechanism. The microstructure of the weld interface between the metal tapes consisted of fine, equiaxed grains resulting from recrystallization, which is driven by simple shear deformation along the ultrasonically vibrating direction of the tape surface. Void formation at the weld interface is attributed to surface asperities resulting from pressure induced by the sonotrode at the initial tape deposition. Transmission electron microscopy revealed that Al–Al metallic bonding without surface oxide layers was mainly achieved, although some oxide clusters were locally observed at the original interface. The results suggest that the oxide layers were broken up and then locally clustered on the interface by ultrasonic vibration

  14. Shear texture and recrystallization texture formation in high speed hot rolling of Al-Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, T.; Lee, S.H.; Yoneda, K.; Hamada, S.; Saito, Y. [Dept. of Materials Science and Engineering, Osaka Univ., Osaka (Japan)

    2001-07-01

    Effects of inhomogeneous shear strain distribution through the thickness of hot rolled Al-Mg alloy sheet on recrystallization behavior and texture formation has been investigated. Al-2.5%Mg alloy sheets were rolled to various reductions at the temperature of 460 to 560 C. Due to the high friction, severely sheared region was formed beneath the surface. A band of equiaxed grains is formed at the severely sheared region by recrystallization immediately after rolling. The deformation texture consisted mainly of {l_brace}111{r_brace} left angle 110 right angle, {l_brace}112{r_brace} left angle 110 right angle and {l_brace}001{r_brace} left angle 110 right angle in the severely sheared region. The recrystallization texture in severely sheared region retained the components of deformation texture, although intensities became weak with the progress of recrystallization. (orig.)

  15. 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.

  16. Quasicrystal formation, phase selection and crystallization kinetics in Zr-Cu-Ni-Al based metallic glasses

    International Nuclear Information System (INIS)

    Quaternary Zr-Cu-Ni-Al is one of the best glass forming alloys known. In a narrow concentration range icosahedral quasicrystals are formed upon annealing; in Zr69.5Cu12Ni11Al7.5 the metastable primitive icosahedral phase is probably oxygen stabilized. At slightly higher oxygen contents (about 1 at.%) the formation of a metastable fcc ''big-cube'' phase (NiTi2-type) is competing with very high nucleation rates. The aim of this paper is to investigate in detail the formation of quasicrystals as well as microstructures consisting of the ''big-cube'' phase in order to design in particular nanocrystalline structures by controlled crystallization. Nucleation rates were measured by means of crystallization statistics. By modeling the obtained nucleation rates in the framework of diffusion controlled classical nucleation interfacial energies as well as melting temperatures for the metastable phases could be derived. Atomic mobility was estimated from growth data. Using these data TTT-diagrams can be drawn and microstructures (for example nanocrystalline) predicted. The phase selection during the formation of the metastable structures was observed to depend strongly not only on the exchange of the Zr by Hf or Ti, but also on the late transition elements chosen, hydrogen or oxygen contamination as well as on alloying with small amounts of other elements for example Si, Sn, Y or Mo. Regarding the influence of the late transition metals there is some evidence that the quasicrystals are a hybrid of two structural elements, i.e. the tetragonal Zr2Ni(Al2Cu) and the tetragonal Zr2Cu (MoSi2) structure. The mentioned alloying elements as well as oxygen and hydrogen are assumed to influence the arrangement of the structural elements towards one or the other structure. (orig.)

  17. 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.

  18. 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.

  19. Defect formation in MgOxnAl2O3 at gamma-neutron irradiation

    International Nuclear Information System (INIS)

    Optical and mechanical characteristics of spinel crystals after reactor irradiation are investigated. The comparison of the concentrations of radiation-induced anion vacancies and stable F-centers has shown that less than one tenth of the point defects is stabilized at room temperature. The annealing of these vacancies occurs at 800 K. The vacancy formation during gamma-neutron irradiation of nominally pure spinel crystals improves the crack resistance. The irradiation of Fe- and Mn ion-doped crystals MgOxnAl2O3, is accompanied by the coagulation stresses and crack resistance decrease

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Microstructure-controlled effects on temperature reduction of α-Al 2O 3 crystallite formation

    Science.gov (United States)

    Yang, Rung-Je; Yen, Fu-Su; Lin, Shen-Min; Chen, Chih-Cheng

    2007-02-01

    The inter-particle relationship effects on a temperature reduction and simultaneity of α-crystallite formation during θ- to α-phase transformation were examined using DTA, XRD, and TEM techniques. Three powder systems derived from the same θ-powder of average crystallite size 15.2 nm were prepared, with the intention of creating different microstructure for each powder systems as: (1) as-received, (2) pre-treated by homogenization with a mechanical stirring accompanied by pH adjustment for dispersion, and (3) homogenized and additionally uniaxial-pressed to compacts with higher bulk density. Activation energies of θ-crystallite growth occurring in the three powder systems were also obtained based on an isothermal model of grain growth rate equation. It is found that the temperature reduction characteristics can be related to the homogeneity as well as the inter θ-Al 2O 3 crystallite distances behaved by the θ-crystallites. Higher homogeneity and shorter inter-crystallite distance for the θ-powder systems may favor the α-crystallite formation at lower temperatures over a shorter duration of phase transformation. Furthermore, activation energies of θ-crystallite growth can be reduced. And α-Al 2O 3 powders fabricated can be mono-sized and free of vermicular growth.

  5. 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.

  6. 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.

  7. 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.

  8. Formation of Na{sub 3}AlH{sub 6} from a NaH/Al mixture and Ti-containing catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Fang Fang; Zheng Shiyou; Chen Guorong [Department of Materials Science, Fudan University, 220 Handan Road, Shanghai 200433 (China); Sang Ge [Chinese Academy of Engineering Physics, Mianyang 621900 (China); He Bo; Wei Shiqiang [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China); Sun Dalin [Department of Materials Science, Fudan University, 220 Handan Road, Shanghai 200433 (China)], E-mail: dlsun@fudan.edu.cn

    2009-04-15

    To investigate the effects of Ti-containing catalyst on the hydride formation in the Na-Al-H system, Ti(OBu{sup n}){sub 4}- and TiF{sub 3}-doped NaH/Al powders were hydrogenated into Na{sub 3}AlH{sub 6} by controlling the hydrogen pressure at 5 MPa and the temperature at 100-140 deg. C. X-ray diffraction and differential scanning calorimetry showed that TiF{sub 3} was more catalytically favorable than Ti(OBu{sup n}){sub 4} to enhance the formation of Na{sub 3}AlH{sub 6}. X-ray absorption spectroscopy revealed that the initial Ti{sup 4+} or Ti{sup 3+} ions were reduced to Ti{sup 1+} or Ti{sup 0} and form Ti-Al pairs with two coordination shells during the doping and hydrogenation processes. The difference in catalytic activity between the two Ti-containing catalysts can be attributed to their ability to form Ti-Al pairs with the NaH/Al mixture.

  9. Effects of internal hydrogen on the vacancy loop formation probability in Al

    International Nuclear Information System (INIS)

    The effect of internal hydrogen on the formation of vacancy dislocation loops from heavy-ion generated displacement cascades in Al has been investigated. Samples of high-purity aluminum and aluminum containing 900 and 1300 appM of hydrogen were irradiated at room temperature with 50 keV Kr+ ions. The ion dose rate was typically 2 x 1010ions cm-2 sec-1 and the ion dose was between 1011 and 1013 ion cm-2. Under these irradiation conditions, dislocation loops were observed in all compositions, although the formation probability was relatively low (less than 10 percent of the displacement cascades produced a vacancy loop). The loop formation probability was further reduced by the presence of hydrogen. No difference in the geometry or the size of the loops created in the hydrogen free and hydrogen charged samples was found. These results are difficult to interpret, and the explanation may lie in the distribution and form of the hydrogen. To account for the large hydrogen concentrations and from calculations of the energy associated with hydrogen entry into aluminum, it has been suggested that the hydrogen enters the aluminum lattice with an accompanying vacancy. This will create hydrogen-vacancy complexes in the material; two dimensional complexes have been detected in the hydrogen-charged, but unirradiated, samples by the small-angle x-ray scattering technique. The possibility of these complexes trapping the vacancies produced by the cascade process exists thus lowering the formation probability. However, such a mechanism must occur within the lifetime of the cascade. Alternatively, if a displacement cascade overlaps with the hydrogen-vacancy complexes, the lower atomic density of the region will result in an increase in the cascade volume (decrease in the local vacancy concentration) which will also reduce the loop formation probability

  10. 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)

  11. Promotion

    OpenAIRE

    Alam, Hasan B.

    2013-01-01

    This article gives an overview of the promotion process in an academic medical center. A description of different promotional tracks, tenure and endowed chairs, and the process of submitting an application is provided. Finally, some practical advice about developing skills and attributes that can help with academic growth and promotion is dispensed.

  12. 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.

  13. Thrombospondin 1 promotes synaptic formation in bone marrow-derived neuron-like cells

    Institute of Scientific and Technical Information of China (English)

    Yun Huang; Mingnan Lu; Weitao Guo; Rong Zeng; Bin Wang; Huaibo Wang

    2013-01-01

    In this study, a combination of growth factors was used to induce bone marrow mesenchymal stem cells differentiation into neuron-like cells, in a broader attempt to observe the role of thrombospondin 1 in synapse formation. Results showed that there was no significant difference in the differentiation rate of neuron-like cells between bone marrow mesenchymal stem cells with thrombospondin induction and those without. However, the cell shape was more complex and the neurites were dendritic, with unipolar, bipolar or multipolar morphologies, after induction with thrombospondin 1. The induced cells were similar in morphology to normal neurites. Immunohistochemical staining showed that the number of positive cells for postsynaptic density protein 95 and synaptophysin 1 protein was significantly increased after induction with thrombospondin 1. These findings indicate that thrombospondin 1 promotes synapse formation in neuron-like cells that are differentiated from bone marrow mesenchymal stem cells.

  14. 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.

  15. Control of bcc and fcc phase formation during mechanical alloying of Ti-Al-Nb

    International Nuclear Information System (INIS)

    A Ti-Al-Nb alloy was processed by ball milling or mechanical alloying in a high energy shaker mill in an attempt to produce a fine grained BCC alloy. Previous studies of this alloy resulted in the formation of an amorphous phase followed by a 100% FCC alloy (probably a nitride phase). In the present study, ball milling was conducted in two different laboratories with nitride- and oxide-free starting powders in each location. Two types of starting powders were used: pre-alloyed powders and mixed elemental powders of the same composition. The production of a 90% BCC/10% FCC alloy was accomplished indicating that the production of 100% BCC alloy may be possible. The methods used to prevent the formation of nitrides and oxides of these very reactive constituents during mechanical alloying are discussed and x-ray diffraction results of the mechanically alloyed powders milled by various techniques are presented. The most important factor leading to amorphization and FCC phase formation appears to be contamination associated with periodic sampling of the alloy during ball milling even when dry, inert gas gloveboxes are used for powder transfer

  16. Biosurfactant as a Promoter of Methane Hydrate Formation: Thermodynamic and Kinetic Studies

    Science.gov (United States)

    Arora, Amit; Cameotra, Swaranjit Singh; Kumar, Rajnish; Balomajumder, Chandrajit; Singh, Anil Kumar; Santhakumari, B.; Kumar, Pushpendra; Laik, Sukumar

    2016-02-01

    Natural gas hydrates (NGHs) are solid non-stoichiometric compounds often regarded as a next generation energy source. Successful commercialization of NGH is curtailed by lack of efficient and safe technology for generation, dissociation, storage and transportation. The present work studied the influence of environment compatible biosurfactant on gas hydrate formation. Biosurfactant was produced by Pseudomonas aeruginosa strain A11 and was characterized as rhamnolipids. Purified rhamnolipids reduced the surface tension of water from 72 mN/m to 36 mN/m with Critical Micelle Concentration (CMC) of 70 mg/l. Use of 1000 ppm rhamnolipids solution in C type silica gel bed system increased methane hydrate formation rate by 42.97% and reduced the induction time of hydrate formation by 22.63% as compared to water saturated C type silica gel. Presence of rhamnolipids also shifted methane hydrate formation temperature to higher values relative to the system without biosurfactant. Results from thermodynamic and kinetic studies suggest that rhamnolipids can be applied as environment friendly methane hydrate promoter.

  17. 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.

  18. 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

  19. 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.

  20. Prediction of formation enthalpies for Al2X-type intermetallics using back-propagation neural network

    International Nuclear Information System (INIS)

    Research highlights: → An ANN was built to predict the formation enthalpies of Al2X-type intermetallics. → The values predicted by the ANN agree with experiments well to typically within 10%. → The method comparison suggests that our ANN method is superior to Miedema's model. → Some trends of formation enthalpies for Al2X-type intermetallics were observed. - Abstract: A back-propagation artificial neural network (ANN) was established to predict the formation enthalpies of Al2X-type intermetallics as a function of some physical parameters. These physical parameters include the electronegativity difference, the electron density difference, the atomic size difference, and the electron-atom ratio (e/a). The values calculated by the ANN method agree with experiments well to typically within 10%, indicating that the well-trained back-propagation (BP) neural network is feasible, and can precisely predict the formation enthalpies of Al2X-type intermetallics. The method comparison based on the predicted formation enthalpies suggests that our ANN method is superior to Miedema's model. Some trends of formation enthalpies for Al2X-type intermetallics were also observed from the ANN.

  1. Investigation of the thermal diffusion during the formation of a quasicrystalline phase in thin Al-Pd-Re films

    International Nuclear Information System (INIS)

    The layer mixing during the formation of the Al70Pd20Re10 icosahedral quasicrystalline phase in thin (55 nm) Al-Pd-Re layered film systems subjected to vacuum annealing has been studied. It is shown that a combined layer of Pd and Al atoms (with the Al3Pd2 phase dominating) is formed in the first stage (at 350°C), while the rhenium layer remains invariable. In the second annealing stage (at 450°C), the β′-AlPd phase is formed and the Re layer is diffused. In the third stage (700°C), Pd and Re atoms are uniformly distributed throughout the film with the formation of a quasicrystalline phase.

  2. 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.

  3. 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.

  4. 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.

  5. Periostin promotes immunosuppressive premetastatic niche formation to facilitate breast tumour metastasis.

    Science.gov (United States)

    Wang, Zhe; Xiong, Shanshan; Mao, Yubin; Chen, Mimi; Ma, Xiaohong; Zhou, Xueliang; Ma, Zhenling; Liu, Fan; Huang, Zhengjie; Luo, Qi; Ouyang, Gaoliang

    2016-08-01

    Periostin (POSTN) is a limiting factor in the metastatic colonization of disseminated tumour cells. However, the role of POSTN in regulating the immunosuppressive function of immature myeloid cells in tumour metastasis has not been documented. Here, we demonstrate that POSTN promotes the pulmonary accumulation of myeloid-derived suppressor cells (MDSCs) during the early stage of breast tumour metastasis. Postn deletion decreases neutrophil and monocytic cell populations in the bone marrow of mice and suppresses the accumulation of MDSCs to premetastatic sites. We also found that POSTN-deficient MDSCs display reduced activation of ERK, AKT and STAT3 and that POSTN deficiency decreases the immunosuppressive functions of MDSCs during tumour progression. Moreover, the pro-metastatic role of POSTN is largely limited to ER-negative breast cancer patients. Lysyl oxidase contributes to POSTN-promoted premetastatic niche formation and tumour metastasis. Our findings indicate that POSTN is essential for immunosuppressive premetastatic niche formation in the lungs during breast tumour metastasis and is a potential target for the prevention and treatment of breast tumour metastasis. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. PMID:27193093

  6. 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.

  7. H sup - formation in grazing collisions of fast protons with an Al(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Wyputta, F.; Zimny, R.; Winter, H. (Inst. fuer Kernphysik, Univ. Muenster (Germany))

    1991-06-01

    We have investigated fractions of negative hydrogen atoms after the interaction of fast protons with energies ranging from 1-30 keV with a clean Al(111) surface under grazing angles of incidence. The observed H{sup -} fractions are generally small (<0.5%) and depend strongly on the angle of emergence and the state of preparation of the target surface. We find a resonance type of dependence for the negative ion yield on projectile velocity component parallel to the surface plane, which can be understood in a model of resonant one-electron tunneling between surface and atom. This model implies that H{sup -} formation in grazing surface scattering proceeds in a two-step process of single-electron transfer. (orig.).

  8. 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.

  9. RIPK1 mediates axonal degeneration by promoting inflammation and necroptosis in ALS.

    Science.gov (United States)

    Ito, Yasushi; Ofengeim, Dimitry; Najafov, Ayaz; Das, Sudeshna; Saberi, Shahram; Li, Ying; Hitomi, Junichi; Zhu, Hong; Chen, Hongbo; Mayo, Lior; Geng, Jiefei; Amin, Palak; DeWitt, Judy Park; Mookhtiar, Adnan Kasim; Florez, Marcus; Ouchida, Amanda Tomie; Fan, Jian-bing; Pasparakis, Manolis; Kelliher, Michelle A; Ravits, John; Yuan, Junying

    2016-08-01

    Mutations in the optineurin (OPTN) gene have been implicated in both familial and sporadic amyotrophic lateral sclerosis (ALS). However, the role of this protein in the central nervous system (CNS) and how it may contribute to ALS pathology are unclear. Here, we found that optineurin actively suppressed receptor-interacting kinase 1 (RIPK1)-dependent signaling by regulating its turnover. Loss of OPTN led to progressive dysmyelination and axonal degeneration through engagement of necroptotic machinery in the CNS, including RIPK1, RIPK3, and mixed lineage kinase domain-like protein (MLKL). Furthermore, RIPK1- and RIPK3-mediated axonal pathology was commonly observed in SOD1(G93A) transgenic mice and pathological samples from human ALS patients. Thus, RIPK1 and RIPK3 play a critical role in mediating progressive axonal degeneration. Furthermore, inhibiting RIPK1 kinase may provide an axonal protective strategy for the treatment of ALS and other human degenerative diseases characterized by axonal degeneration. PMID:27493188

  10. 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.

  11. 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.

  12. On the Texture Formation of Selective Laser Melted Ti-6Al-4V

    Science.gov (United States)

    Simonelli, Marco; Tse, Yau Yau; Tuck, Chris

    2014-06-01

    Selective laser melting (SLM) has been shown to be an attractive manufacturing route for the production of α/ β titanium alloys. The relationship between the SLM process parameters and the microstructure of titanium alloys has been the object of several works, but the texture formation during the SLM process has yet to be understood. In the present study, the texture formation of Ti-6Al-4V components was investigated in order to clarify which microstructural features can be tailored during the SLM process. The microstructural characterization of the as-built components was carried out using various microscopy techniques. Phase and texture analysis were carried out using backscattered electron imaging and diffraction. It was found that as-built components consist exclusively of α' martensitic phase precipitated from prior β columnar grains. The texture of the prior β phase was reconstructed and discussed in relation to the used SLM process parameters. It was found that the β grain solidification is influenced by the laser scan strategy and that the β phase has a strong texture along its grain growth direction. The α' martensitic laths that originate from the parent β grains precipitate according to the Burgers orientation relationship. It was observed that α' laths clusters from the same β grain have a specific misorientation that minimizes the local shape strain. Texture inheritance across successive deposited layers was also observed and discussed in relation to various variant selection mechanisms.

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. Nanovoid formation by change in amorphous structure through the annealing of amorphous Al2O3 thin films

    International Nuclear Information System (INIS)

    The formation mechanism of a high density of nanovoids by annealing amorphous Al2O3 thin films prepared by an electron beam deposition method was investigated. Transmission electron microscopy observations revealed that nanovoids ∼1-2 nm in size were formed by annealing amorphous Al2O3 thin films at 973 K for 1-12 h, where the amorphous state was retained. The elastic stiffness, measured by a picosecond laser ultrasound method, and the density, measured by X-ray reflectivity, increased drastically after the annealing process, despite nanovoid formation. These increases indicate a change in the amorphous structure during the annealing process. Molecular dynamics simulations indicated that an increase in stable AlO6 basic units and the change in the ring distribution lead to a drastic increase in both the elastic stiffness and the density. It is probable that a pre-annealed Al2O3 amorphous film consists of unstable low-density regions containing a low fraction of stable AlO6 units and stable high-density regions containing a high fraction of stable AlO6 units. Thus, local density growth in the unstable low-density regions during annealing leads to nanovoid formation (i.e., local volume shrinkage).

  18. Sympathetic stimulation facilitates thrombopoiesis by promoting megakaryocyte adhesion, migration, and proplatelet formation.

    Science.gov (United States)

    Chen, Shilei; Du, Changhong; Shen, Mingqiang; Zhao, Gaomei; Xu, Yang; Yang, Ke; Wang, Xinmiao; Li, Fengju; Zeng, Dongfeng; Chen, Fang; Wang, Song; Chen, Mo; Wang, Cheng; He, Ting; Wang, Fengchao; Wang, Aiping; Cheng, Tianmin; Su, Yongping; Zhao, Jinghong; Wang, Junping

    2016-02-25

    The effect of sympathetic stimulation on thrombopoiesis is not well understood. Here, we demonstrate that both continual noise and exhaustive exercise elevate peripheral platelet levels in normal and splenectomized mice, but not in dopamine β-hydroxylase-deficient (Dbh(-/-)) mice that lack norepinephrine (NE) and epinephrine (EPI). Further investigation demonstrates that sympathetic stimulation via NE or EPI injection markedly promotes platelet recovery in mice with thrombocytopenia induced by 6.0 Gy of total-body irradiation and in mice that received bone marrow transplants after 10.0 Gy of lethal irradiation. Unfavorably, sympathetic stress-stimulated thrombopoiesis may also contribute to the pathogenesis of atherosclerosis by increasing both the amount and activity of platelets in apolipoprotein E-deficient (ApoE(-/-)) mice. In vitro studies reveal that both NE and EPI promote megakaryocyte adhesion, migration, and proplatelet formation (PPF) in addition to the expansion of CD34(+) cells, thereby facilitating platelet production. It is found that α2-adrenoceptor-mediated extracellular signal-regulated kinase 1/2 (ERK1/2) activation is involved in NE- and EPI-induced megakaryocyte adhesion and migration, and PPF is regulated by ERK1/2 activation-mediated RhoA GTPase signaling. Our data deeply characterize the role of sympathetic stimulation in the regulation of thrombopoiesis and reevaluate its physiopathological implications. PMID:26644453

  19. 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.

  20. Formation mechanism and control of MgO·Al2O3 inclusions in non-oriented silicon steel

    Institute of Scientific and Technical Information of China (English)

    Yan-hui Sun; Ya-nan Zeng; Rui Xu; Kai-ke Cai

    2014-01-01

    On the basis of the practical production of non-oriented silicon steel, the formation of MgO·Al2O3 inclusions was analyzed in the process of “basic oxygen furnace (BOF)→ RH→ compact strip production (CSP)”. The thermodynamic and kinetic conditions of the for-mation of MgO·Al2O3 inclusions were discussed, and the behavior of slag entrapment in molten steel during RH refining was simulated by computational fluid dynamics (CFD) software. The results showed that the MgO/Al2O3mass ratio was in the range from 0.005 to 0.017 and that MgO·Al2O3 inclusions were not observed before the RH refining process. In contrast, the MgO/Al2O3 mass ratio was in the range from 0.30 to 0.50, and the percentage of MgO·Al2O3spinel inclusions reached 58.4% of the total inclusions after the RH refining process. The compositions of the slag were similar to those of the inclusions; furthermore, the critical velocity of slag entrapment was calculated to be 0.45 m·s−1 at an argon flow rate of 698 L·min−1, as simulated using CFD software. When the test steel was in equilibrium with the slag, [Mg] was 0.00024wt%–0.00028wt% and [Al]s was 0.31wt%–0.37wt%; these concentrations were theoretically calculated to fall within the MgO·Al2O3 formation zone, thereby leading to the formation of MgO·Al2O3inclusions in the steel. Thus, the formation of MgO·Al2O3 inclusions would be inhibited by reducing the quantity of slag entrapment, controlling the roughing slag during casting, and controlling the composition of the slag and the MgO content in the ladle refractory.

  1. Formation of spinel inclusions in molten stainless steel under Al deoxidation with slags; Slag kyozonka no Al datsusan katei ni okeru stainless yokochu spinel kaizaibutsu no seisei

    Energy Technology Data Exchange (ETDEWEB)

    Nishi, T.; Shinme, K. [Sumitomo Metal Industries, Ltd., Osaka (Japan)

    1998-12-01

    Morphology change of inclusions were experimentally investigated under Al deoxidation of molten stainless steel with CaO-SiO{sub 2}-Al{sub 2}O{sub 3}-MgO slags in order to clarify the morphology control factor of inclusions. 15kg of molten 18mass%Cr-8mass%Ni stainless steels were deoxidized by aluminum at 1873K, and the samples were taken at intervals to observe the inclusions by SEM and EDS. As the results, MgO contents of alumina type inclusions were gradually increased with time and the maximum contents were affected by a CaO/SiO{sub 2} ratio in slags. The formation of MgO-Al{sub 2}O{sub 3} spine type inclusions were also observed in case of high CaO/SiO{sub 2} ratio. The origin of Mg in inclusions was presumed to be deformation of MgO in slags. (author)

  2. 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

  3. Histone deacetylase degradation and MEF2 activation promote the formation of slow-twitch myofibers.

    Science.gov (United States)

    Potthoff, Matthew J; Wu, Hai; Arnold, Michael A; Shelton, John M; Backs, Johannes; McAnally, John; Richardson, James A; Bassel-Duby, Rhonda; Olson, Eric N

    2007-09-01

    Skeletal muscle is composed of heterogeneous myofibers with distinctive rates of contraction, metabolic properties, and susceptibility to fatigue. We show that class II histone deacetylase (HDAC) proteins, which function as transcriptional repressors of the myocyte enhancer factor 2 (MEF2) transcription factor, fail to accumulate in the soleus, a slow muscle, compared with fast muscles (e.g., white vastus lateralis). Accordingly, pharmacological blockade of proteasome function specifically increases expression of class II HDAC proteins in the soleus in vivo. Using gain- and loss-of-function approaches in mice, we discovered that class II HDAC proteins suppress the formation of slow twitch, oxidative myofibers through the repression of MEF2 activity. Conversely, expression of a hyperactive form of MEF2 in skeletal muscle of transgenic mice promotes the formation of slow fibers and enhances running endurance, enabling mice to run almost twice the distance of WT littermates. Thus, the selective degradation of class II HDACs in slow skeletal muscle provides a mechanism for enhancing physical performance and resistance to fatigue by augmenting the transcriptional activity of MEF2. These findings provide what we believe are new insights into the molecular basis of skeletal muscle function and have important implications for possible therapeutic interventions into muscular diseases. PMID:17786239

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Production of hydrogen via steam reforming of biofuels on Ni/CeO{sub 2}-Al{sub 2}O{sub 3} catalysts promoted by noble metals

    Energy Technology Data Exchange (ETDEWEB)

    Profeti, Luciene P.R.; Ticianelli, Edson A.; Assaf, Elisabete M. [Universidade de Sao Paulo, Instituto de Quimica de Sao Carlos, C.P. 780, CEP 13560-970, Sao Carlos - SP (Brazil)

    2009-06-15

    The catalytic activity of Ni/CeO{sub 2}-Al{sub 2}O{sub 3} catalysts modified with noble metals (Pt, Ir, Pd and Ru) was investigated for the steam reform of ethanol and glycerol. The catalysts were characterized by the following techniques: Energy-dispersive X-ray, BET, X-ray diffraction, temperature-programmed reduction, UV-vis diffuse reflectance spectroscopy and X-ray absorption near edge structure (XANES). The results showed that the formation of inactive nickel aluminate was prevented by the presence of CeO{sub 2} dispersed on alumina. The promoting effect of noble metals included a decrease in the reduction temperatures of NiO species interacting with the support, due to the hydrogen spillover effect. It was seen that the addition of noble metal stabilized the Ni sites in the reduced state along the reforming reaction, increasing the ethanol and glycerol conversions and decreasing the coke formation. The higher catalytic performance for the ethanol steam reforming at 600 C and glycerol steam reforming was obtained for the NiPd and NiPt catalysts, respectively, which presented an effluent gaseous mixture with the highest H{sub 2} yield with reasonably low amounts of CO. (author)

  13. Promoting Strong Metal Support Interaction: Doping ZnO for Enhanced Activity of Cu/ZnO:M (M = Al, Ga, Mg) Catalysts

    OpenAIRE

    J. Schumann; Eichelbaum, M; Lunkenbein, T.; Thomas, N; Alvarez Galvan, M.; Schlögl, R.; Behrens, M.

    2015-01-01

    The promoting effect of Al, Ga, and Mg on the support in Cu/ZnO catalysts for methanol synthesis has been investigated. Different unpromoted and promoted ZnO supports were synthesized and impregnated with Cu metal in a subsequent step. All materials, supports, and calcined and activated catalysts were characterized by various methods, including contactless (microwave) conductivity measurements under different gas atmospheres. Small amounts of promoters were found to exhibit a significant infl...

  14. Promotion of experimental thrombus formation by the procoagulant activity of breast cancer cells

    International Nuclear Information System (INIS)

    The routine observation of tumor emboli in the peripheral blood of patients with carcinomas raises questions about the clinical relevance of these circulating tumor cells. Thrombosis is a common clinical manifestation of cancer, and circulating tumor cells may play a pathogenetic role in this process. The presence of coagulation-associated molecules on cancer cells has been described, but the mechanisms by which circulating tumor cells augment or alter coagulation remains unclear. In this study we utilized suspensions of a metastatic adenocarcinoma cell line, MDA-MB-231, and a non-metastatic breast epithelial cell line, MCF-10A, as models of circulating tumor cells to determine the thromobogenic activity of these blood-foreign cells. In human plasma, both metastatic MDA-MB-231 cells and non-metastatic MCF-10A cells significantly enhanced clotting kinetics. The effect of MDA-MB-231 and MCF-10A cells on clotting times was cell number-dependent and inhibited by a neutralizing antibody to tissue factor (TF) as well as inhibitors of activated factor X and thrombin. Using fluorescence microscopy, we found that both MDA-MB-231 and MCF-10A cells supported the binding of fluorescently labeled thrombin. Furthermore, in a model of thrombus formation under pressure-driven flow, MDA-MB-231 and MCF-10A cells significantly decreased the time to occlusion. Our findings indicate that the presence of breast epithelial cells in blood can stimulate coagulation in a TF-dependent manner, suggesting that tumor cells that enter the circulation may promote the formation of occlusive thrombi under shear flow conditions

  15. 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

  16. Promotion of experimental thrombus formation by the procoagulant activity of breast cancer cells

    Science.gov (United States)

    Berny-Lang, M. A.; Aslan, J. E.; Tormoen, G. W.; Patel, I. A.; Bock, P. E.; Gruber, A.; McCarty, O. J. T.

    2011-02-01

    The routine observation of tumor emboli in the peripheral blood of patients with carcinomas raises questions about the clinical relevance of these circulating tumor cells. Thrombosis is a common clinical manifestation of cancer, and circulating tumor cells may play a pathogenetic role in this process. The presence of coagulation-associated molecules on cancer cells has been described, but the mechanisms by which circulating tumor cells augment or alter coagulation remains unclear. In this study we utilized suspensions of a metastatic adenocarcinoma cell line, MDA-MB-231, and a non-metastatic breast epithelial cell line, MCF-10A, as models of circulating tumor cells to determine the thromobogenic activity of these blood-foreign cells. In human plasma, both metastatic MDA-MB-231 cells and non-metastatic MCF-10A cells significantly enhanced clotting kinetics. The effect of MDA-MB-231 and MCF-10A cells on clotting times was cell number-dependent and inhibited by a neutralizing antibody to tissue factor (TF) as well as inhibitors of activated factor X and thrombin. Using fluorescence microscopy, we found that both MDA-MB-231 and MCF-10A cells supported the binding of fluorescently labeled thrombin. Furthermore, in a model of thrombus formation under pressure-driven flow, MDA-MB-231 and MCF-10A cells significantly decreased the time to occlusion. Our findings indicate that the presence of breast epithelial cells in blood can stimulate coagulation in a TF-dependent manner, suggesting that tumor cells that enter the circulation may promote the formation of occlusive thrombi under shear flow conditions.

  17. 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.

  18. 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.

  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. Differential survival of solitary and aggregated bacterial cells promotes aggregate formation on leaf surfaces

    Science.gov (United States)

    Monier, J.-M.; Lindow, S. E.

    2003-01-01

    The survival of individual Pseudomonas syringae cells was determined on bean leaf surfaces maintained under humid conditions or periodically exposed to desiccation stress. Cells of P. syringae strain B728a harboring a GFP marker gene were visualized by epifluorescence microscopy, either directly in situ or after recovery from leaves, and dead cells were identified as those that were stained with propidium iodide in such populations. Under moist, conducive conditions on plants, the proportion of total live cells was always high, irrespective of their aggregated state. In contrast, the proportion of the total cells that remained alive on leaves that were periodically exposed to desiccation stress decreased through time and was only ≈15% after 5 days. However, the fraction of cells in large aggregates that were alive on such plants in both condition was much higher than more solitary cells. Immediately after inoculation, cells were randomly distributed over the leaf surface and no aggregates were observed. However, a very aggregated pattern of colonization was apparent within 7 days, and >90% of the living cells were located in aggregates of 100 cells or more. Our results strongly suggest that, although conducive conditions favor aggregate formation, such cells are much more capable of tolerating environmental stresses, and the preferential survival of cells in aggregates promotes a highly clustered spatial distribution of bacteria on leaf surfaces. PMID:14665692

  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. Unfractionated Heparin Promotes Osteoclast Formation in Vitro by Inhibiting Osteoprotegerin Activity

    Directory of Open Access Journals (Sweden)

    Binghan Li

    2016-04-01

    Full Text Available Heparin has been proven to enhance bone resorption and induce bone loss. Since osteoclasts play a pivotal role in bone resorption, the effect of heparin on osteoclastogenesis needs to be clarified. Since osteocytes are the key modulator during osteoclastogenesis, we evaluated heparin’s effect on osteoclastogenesis in vitro by co-culturing an osteocyte cell line (MLO-Y4 and pre-osteoclasts (RAW264.7. In this co-culture system, heparin enhanced osteoclastogenesis and osteoclastic bone resorption while having no influence on the production of RANKL (receptor activator of NFκB ligand, M-CSF (macrophage colony-stimulating factor, and OPG (osteoprotegerin, which are three main regulatory factors derived from osteocytes. According to previous studies, heparin could bind specifically to OPG and inhibit its activity, so we hypothesized that this might be a possible mechanism of heparin activity. To test this hypothesis, osteoclastogenesis was induced using recombinant RANKL or MLO-Y4 supernatant. We found that heparin has no effect on RANKL-induced osteoclastogenesis (contains no OPG. However, after incubation with OPG, the capacity of MLO-Y4 supernatant for supporting osteoclast formation was increased. This effect disappeared after OPG was neutralized and reappeared after OPG was replenished. These results strongly suggest that heparin promotes osteocyte-modulated osteoclastogenesis in vitro, at least partially, through inhibiting OPG activity.

  4. Unfractionated Heparin Promotes Osteoclast Formation in Vitro by Inhibiting Osteoprotegerin Activity.

    Science.gov (United States)

    Li, Binghan; Lu, Dan; Chen, Yuqing; Zhao, Minghui; Zuo, Li

    2016-01-01

    Heparin has been proven to enhance bone resorption and induce bone loss. Since osteoclasts play a pivotal role in bone resorption, the effect of heparin on osteoclastogenesis needs to be clarified. Since osteocytes are the key modulator during osteoclastogenesis, we evaluated heparin's effect on osteoclastogenesis in vitro by co-culturing an osteocyte cell line (MLO-Y4) and pre-osteoclasts (RAW264.7). In this co-culture system, heparin enhanced osteoclastogenesis and osteoclastic bone resorption while having no influence on the production of RANKL (receptor activator of NFκB ligand), M-CSF (macrophage colony-stimulating factor), and OPG (osteoprotegerin), which are three main regulatory factors derived from osteocytes. According to previous studies, heparin could bind specifically to OPG and inhibit its activity, so we hypothesized that this might be a possible mechanism of heparin activity. To test this hypothesis, osteoclastogenesis was induced using recombinant RANKL or MLO-Y4 supernatant. We found that heparin has no effect on RANKL-induced osteoclastogenesis (contains no OPG). However, after incubation with OPG, the capacity of MLO-Y4 supernatant for supporting osteoclast formation was increased. This effect disappeared after OPG was neutralized and reappeared after OPG was replenished. These results strongly suggest that heparin promotes osteocyte-modulated osteoclastogenesis in vitro, at least partially, through inhibiting OPG activity. PMID:27110777

  5. Evidence for the formation of Al-rich reservoir phases resulting from interdiffusion between MCrAlY coating and Ni-based substrate

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, M.P.; Pragnell, W.M.; Evans, H.E. [Dept. of Metallurgy and Materials, Univ. of Birmingham, Edgbaston (United Kingdom)

    2004-07-01

    In this paper the results of a study of the interdiffusion between an LPPS CoNiCrAlY coating with a Ni-based CM186 alloy substrate are shown. Accelerated oxidation testing at 1200 C is used to demonstrate the sequence of changes occurring to the microstructure of the interdiffusion zone with increasing time at temperature. The evolving microstructural features have been identified using high resolution scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Elemental profiles of the diffusion zone at different times at temperature are compared to a computational model predicting such profiles. It is found that aluminium ingress into the alloy, as predicted by the model, is inhibited by the formation of Al-rich phases in the interfacial zone. With extended time at temperature, aluminium depletion within the coating triggers the dissociation of these phases. These then act as reservoirs and supply aluminium back into the coating. (orig.)

  6. Mechanism of ZrB2 Formation in Molten Al-V-Zr Alloy During Boron Treatment

    Science.gov (United States)

    Khaliq, Abdul; Rhamdhani, Muhammad Akbar; Brooks, Geoffrey A.; Grandfield, John

    2016-02-01

    Smelter-grade aluminum cannot be used for electrical conductor applications without the removal of transition metal impurities including zirconium (Zr) and vanadium (V). These impurities are removed by treating molten aluminum with boron bearing substances in the casthouse. Such procedures are called boron treatment. Transition metal impurities form their borides and settle at bottom of the furnace. Industrially, Al-B (AlB2/AlB12) master alloys are used for this process. Literature review showed that ZrB2 are more stable compared to VB2 and AlB2 in the temperatures ranging from 948 K to 1173 K (675 °C to 900 °C). As a result, ZrB2 will form preferentially in molten aluminum during boron treatment process. In this study, a systematic investigation on formation of the ZrB2 and VB2 borides in Al-V-Zr-B alloys was carried out at 1023 K (750 °C). Experiments showed that the mechanism of ZrB2 and VB2 borides formation in molten aluminum is complex. It involves the possible phenomenon of chemical reactions, mass transfer in liquid phase, diffusion through borides layers, and the dissolution of Al3Zr, AlB2/AlB12 in the molten aluminum. Scanning electron microscopy, Energy-dispersive X-ray, and electron backscattered diffraction analyses revealed the preferential formation of ZrB2 in the Al-Zr-V-B alloys at 1023 K (750 °C). Moreover, ICP-AES analysis showed the higher rate of Zr removal compared to V from Al-Zr-V-B alloys. Overall it was suggested that the kinetics of Zr removal was controlled by the mass transfer of Zr through liquid phase. The calculated mass transfer coefficient ( k m) for Zr was 1.15 × 10-3 m/s which is within the range of those values reported in the literature.

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

    OpenAIRE

    A.V. Kotko; Nosenko, V. K.; O.A. Molebny; T.O. Monastyrska; A.L. Berezina

    2012-01-01

    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 supersat...

  8. Femtosecond laser ablation and nanoparticle formation in intermetallic NiAl

    Science.gov (United States)

    Jorgensen, David J.; Titus, Michael S.; Pollock, Tresa M.

    2015-10-01

    The ablation behavior of a stoichiometric intermetallic compound β-NiAl subjected to femtosecond laser pulsing in air has been investigated. The single-pulse ablation threshold for NiAl was determined to be 83 ± 4 mJ/cm2 and the transition to the high-fluence ablation regime occurred at 2.8 ± 0.3 J/cm2. Two sizes of nanoparticles consisting of Al, NiAl, Ni3Al and NiO were formed and ejected from the target during high-fluence ablation. Chemical analysis revealed that smaller nanoparticles (1-30 nm) tended to be rich in Al while larger nanoparticles (>100 nm) were lean in Al. Ablation in the low-fluence regime maintained this trend. Redeposited material and nanoparticles remaining on the surface after a single 3.7 J/cm2 pulse, one hundred 1.7 J/cm2 pulses, or one thousand 250 mJ/cm2 pulses were enriched in Al relative to the bulk target composition. Further, the surface of the irradiated high-fluence region was depleted in Al indicating that the fs laser ablation removal rate of the intermetallic constituents in this regime does not scale with the individual pure element ablation thresholds.

  9. 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.

  10. Multilayered Al/CuO thermite formation by reactive magnetron sputtering: Nano versus micro

    OpenAIRE

    Petrantoni, Marine; Rossi, Carole; Salvagnac, Ludovic; Conédéra, Véronique; Estève, Alain; Tenailleau, Christophe; Alphonse, Pierre; Chabal, Yves J.

    2010-01-01

    Multilayered Al/CuO thermite was deposited by a dc reactive magnetron sputtering method. Pure Al and Cu targets were used in argon–oxygen gas mixture plasma and with an oxygen partial pressure of 0.13 Pa. The process was designed to produce low stress (

  11. 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....

  12. 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)

    QU ShiYu; HAN YaFang; KANG YongWang

    2009-01-01

    The effects of alloying elements Ti, AI and Hf on niobium silicides formation in the Nb-Si in situ com-posites 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 AI 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 ele-ments on niobium silicides formation basically maintain the character of ternary system.

  13. 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

  14. 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.

  15. 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.

  16. Age-hardening effect and formation of nanoscale composite precipitates in a NiAlMnCu-containing steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojiao [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Sha, Gang, E-mail: gang.sha@njust.edu.cn [School of Materials Science & Engineering, Nanjing University of Science and Technology, Jiangsu 210094 (China); Shen, Qin [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China); Liu, Wenqing, E-mail: wqliu@staff.shu.edu.cn [Key Laboratory for Microstructures, Shanghai University, Shanghai 200444 (China)

    2015-03-11

    A NiAlMnCu-containing steel during ageing at 500 °C up to 100 h exhibits an interesting age-hardening effect. Careful atom probe tomography investigations confirm that small clusters, enriched with Ni, Al, Mn and Cu, formed in the steel after a short ageing of 0.25 h. Composite precipitates, consisting of a NiAl-rich and a Cu-rich component side by side, formed after 4 h ageing, a phenomenon which corresponded to a peak of 445 VHN in hardness. A decrease in hardness of the steel occurred after ageing for 100 h, due to the coarsening of the composite precipitates. Quantitative chemical composition measurements reveal that early-stage formation of composite precipitates involves the decomposition of metastable solute clusters, and their growth is associated with the further partitioning of solutes from the ferrite matrix into the composite precipitates.

  17. Mechanism of the formation of peripheral coarse grain structure in hot extrusion of Al-4.5Zn-1Mg

    Science.gov (United States)

    Eivani, A. R.; Zhou, J.; Duszczyk, J.

    2016-04-01

    Microstructural evolution leading to peripheral coarse grain (PCG) structure in hot extruded Al-4.5Zn-1Mg rods is investigated. The extent of dynamic recrystallization (DRX) in the as-extruded product falls not in line with the basis over which the existing mechanisms for interpretation of PCG formation are built. A new mechanism is therefore proposed based on partial DRX during extrusion and nucleation and abnormal growth of statically recrsystallised grains.

  18. Characterization of ZrO 2-promoted Cu/ZnO/nano-Al 2O 3 methanol steam reforming catalysts

    Science.gov (United States)

    Jones, Samuel D.; Neal, Luke M.; Everett, Michael L.; Hoflund, Gar B.; Hagelin-Weaver, Helena E.

    2010-10-01

    Three Cu/ZnO/ZrO 2/Al 2O 3 methanol reforming catalysts were investigated using X-ray photoelectron spectroscopy (XPS). The catalysts which contained ZrO 2 from a monoclinic nanoparticle ZrO 2 precursor exhibit both a higher activity toward the methanol steam reforming reaction and a lower CO production rate compared to catalysts composed of an XRD-amorphous ZrO 2 produced by impregnation using a Zr(NO 3) 2 precursor. The presence of a monoclinic phase appears to result in an increased charge transfer between the Zr and Cu species, as evidenced by a relatively electron-rich ZrO 2 phase and a partially oxidized Cu species on reduced catalysts. This electron deficient Cu species is more reactive toward the methanol reforming reaction and partially suppresses CO formation through the reverse water gas shift or methanol decomposition reactions.

  19. Characterization of ZrO2-promoted Cu/ZnO/nano-Al2O3 methanol steam reforming catalysts

    International Nuclear Information System (INIS)

    Three Cu/ZnO/ZrO2/Al2O3 methanol reforming catalysts were investigated using X-ray photoelectron spectroscopy (XPS). The catalysts which contained ZrO2 from a monoclinic nanoparticle ZrO2 precursor exhibit both a higher activity toward the methanol steam reforming reaction and a lower CO production rate compared to catalysts composed of an XRD-amorphous ZrO2 produced by impregnation using a Zr(NO3)2 precursor. The presence of a monoclinic phase appears to result in an increased charge transfer between the Zr and Cu species, as evidenced by a relatively electron-rich ZrO2 phase and a partially oxidized Cu species on reduced catalysts. This electron deficient Cu species is more reactive toward the methanol reforming reaction and partially suppresses CO formation through the reverse water gas shift or methanol decomposition reactions.

  20. Chip formation in high speed milling of Ti-6Al-4V alloy under nitrogen-oil-mist

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei; HE Ning; LI Liang; MAN Zhong-lei

    2008-01-01

    High speed milling experiments using nitrogen-oil-mist as the cutting medium were carried out to in-vestigate the characteristics of chip formation for Ti-6Al-4V alloy. Within the range of conditions employed in these experiments. During the macro and micro analysis of the Ti-6Al-4V chips, an optical microscope and a scanning electron microscope (SEM) were used to study the microstrocture and the morphology of the chips, and the X-ray photoelectron spectroscopy (XPS) was employed for chemical analysis. Comparisons were made to study the influence of different cutting media (nitrogen-oil-mist, air-oil-mist and dry cutting condition) on chip formation. Results indicate that cutting media have significant effects on chip formation. Nitrogen-oil-mist is more suitable for improving the contact condition at chip-tool interface and increasing the tool life in high speed milling of Ti-6Al-4V alloy than air-oil-mist and dry cutting.

  1. Formation of nanostructured NiAl coating on carbon steel by using mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadnezhad, M., E-mail: M.mohammadnezhad@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shamanian, M.; Enayati, M.H. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Mechanical alloying process could be used for the deposition of nanostructured NiAl intermetallic coatings at ambient atmosphere. Black-Right-Pointing-Pointer Thicker coatings could be formed on the substrate and produced maximum value of around 470 {mu}m after treatment of 480 min. Black-Right-Pointing-Pointer The hardness of the coating on the substrate was more than seven times that of the initial steel substrate. Black-Right-Pointing-Pointer The diffraction patterns before heat treatment, suggests the NiAl intermetallic and another phase and after heat treatment, suggests completely a NiAl intermetallic at 480 min. - Abstract: Nanostructured NiAl intermetallics coatings were generated on carbon steel by using mechanical alloying in ambient temperature and pressure. Ni and Al powders were mixed with the composition of Ni-50 at% Al. The process involved powder particles trapped between the ball and cold welding at surface. Coatings were examined using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the phase transmutation during process and subsequent heat treatment are strongly dependent on mechanical alloying time. After 480 min heat treatment of mechanically alloyed sample, only NiAl peaks were viewed. Ball encounters and failures consecutively reduced the coarse grains of the coating to the nanoscale. The size of nanocrystalline grains in the NiAl coating ranged between 28 and 130 nm. The creation of the coatings was studied at milling intervals between 60 and 600 min. The average thickness and hardness of the surface layers at 480 min, were 470 {mu}m and 930 HV, respectively.

  2. 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  |

  3. The influence of impurities on the formation of protective aluminium oxides on RuAl thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guitar, M.A. [Functional Materials, Materials Science Departament, Saarland University, Saarbrücken D 66123 (Germany); Ramos-Moore, E. [Facultad de Física, Pontificia Universidad Católica de Chile, Santiago 7820436 (Chile); Mücklich, F., E-mail: muecke@matsci.uni-sb.de [Functional Materials, Materials Science Departament, Saarland University, Saarbrücken D 66123 (Germany)

    2014-05-01

    Highlights: • High-temperature oxidation RuAl intermetallic thin films were studied. • Microstructural analysis with and without impurities in the RuAl film. • Effect of impurities content in the oxidation kinetics was evaluated. • Stress evaluation of the oxide grown on RuAl with and without impurities. - Abstract: Single-phase RuAl is a promising candidate for protective coating materials in applications that demand oxidation resistance at temperatures above 600 °C in air. The main advantage of this system over other B2-aluminides emerges from the adherence to α-Al{sub 2}O{sub 3} oxide scale, formed at the surface under thermal cycling conditions. In particular, the presence of impurities and reactive elements may play a crucial role in tailoring the thermo-mechanical properties of the protective oxide. The influence of Cr and Fe impurities in the isothermal oxidation of RuAl thin films deposited on austenitic stainless steel was studied in air at 900 °C. The oxidation kinetics was analysed using an Arrhenius model, whereas microstructural and stress analyses were performed on α-Al{sub 2}O{sub 3} using scanning transmission electron microscopy and X-ray diffraction, respectively. The oxidation behaviour of RuAl was affected by the presence of impurities diffused from austenitic stainless steel substrate. Cracking in the α-Al{sub 2}O{sub 3} layer was observed in the absence of impurities as a result of thermal tensile stresses generated in the oxide scale. On the contrary, compressive stresses were developed after Fe (∼62 at.%) and Cr (∼20 at.%) diffusion into the RuAl film, which enhanced the activation energy of the oxide formation, mainly due to the energy barriers produced at grain boundaries. These findings highlight the potential tailoring of RuAl stability and performance at high temperatures through bottom-up diffusion of impurities and reactive elements from different substrates.

  4. 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.

  5. 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.

  6. Electrochemical formation of Al–Tm intermetallics in eutectic LiCl–KCl melt containing Tm and Al ions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xing [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Yan, Yong-De, E-mail: y5d2006@hrbeu.edu.cn [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin 150001 (China); Zhang, Mi-Lin; Tang, Hao; Ji, De-Bin; Han, Wei [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Xue, Yun; Zhang, Zhi-Jian [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, Harbin Engineering University, Harbin 150001 (China)

    2014-09-15

    This work focuses on investigating the electrochemical formation of Al–Tm and Al–Li–Tm alloys in LiCl–KCl–AlCl{sub 3}–Tm{sub 2}O{sub 3} melt on both W and Al electrodes. Thermodynamic calculation and electrochemical behavior of LiCl–KCl melt containing both AlCl{sub 3} and Tm{sub 2}O{sub 3} showed that AlCl{sub 3} can chlorinate Tm{sub 2}O{sub 3} to release Tm(III) ions. Three kinds of Al–Tm intermetallics at about −1.26, −1.32 and −1.43 V were detected by means of various electrochemical measurement techniques, i.e. cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Potentiostatic and galvanostatic electrolysis were carried out on Al and W electrodes to prepare Al–Tm and Al–Li–Tm alloys, respectively. The composition of Al–Li–Tm alloys was analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES)

  7. Partial hydrogenation of adiponitrile to 6-aminocapronitrile over Ni/α-Al2O3 catalyst promoted with K2O and La2O3

    Institute of Scientific and Technical Information of China (English)

    Lei Zhao; Cai Yun Wang; Ji Xiang Chen; Ji Yan Zhang

    2007-01-01

    A novel K2O and La2O3 promoted nickel catalyst supported on α-Al2O3 was prepared by co-impregnation method, and it exhibited higher activity and 6-aminocapronitrile selectivity than Ni/α-Al2O3 during the hydrogenation of adiponitrile in the absence of ammonia, i.e., K2O and La2O3 improved the performance of the nickel-based catalyst.

  8. Formation of nanostructured NiAl coating on carbon steel by using mechanical alloying

    Science.gov (United States)

    Mohammadnezhad, M.; Shamanian, M.; Enayati, M. H.

    2012-12-01

    Nanostructured NiAl intermetallics coatings were generated on carbon steel by using mechanical alloying in ambient temperature and pressure. Ni and Al powders were mixed with the composition of Ni-50 at% Al. The process involved powder particles trapped between the ball and cold welding at surface. Coatings were examined using X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the phase transmutation during process and subsequent heat treatment are strongly dependent on mechanical alloying time. After 480 min heat treatment of mechanically alloyed sample, only NiAl peaks were viewed. Ball encounters and failures consecutively reduced the coarse grains of the coating to the nanoscale. The size of nanocrystalline grains in the NiAl coating ranged between 28 and 130 nm. The creation of the coatings was studied at milling intervals between 60 and 600 min. The average thickness and hardness of the surface layers at 480 min, were 470 μm and 930 HV, respectively.

  9. Al plasma jet formation via ion stream compression by surrounding low-Z plasma envelope

    Directory of Open Access Journals (Sweden)

    Pisarczyk T.

    2013-11-01

    Full Text Available In our earlier papers it was demonstrated that the plasma pressure decreases with the growing atomic number of the target material. In this context a question arose about the possibility to collimate the Al plasma outflow by using the plastic plasma as a compressor. For that purpose a plastic target with an Al cylindrical insert of 400 μm in diameter was used. The experiment was carried out at the PALS laser facility. The laser provided a 250 ps (FWHM pulse with the energy of 130 J at the third harmonic frequency (λ3 = 0.438 μm. The focal spot diameters (ΦL 800, 1000, and 1200 μm ensured predominance of the plastic plasma, its transversal extension being large enough for the effective Al plasma compression. To study the Al plasma stream propagation and its interaction with the plastic plasma, a 3-frame interferometric system and 4-frame x-ray camera were used. The information on distribution of electron temperature in the outflowing Al plasma was provided by x-ray spectroscopy. The experimental results reported in the paper are discussed by virtue of a simple theoretical analysis.

  10. Multilayered Al/CuO thermite formation by reactive magnetron sputtering: Nano versus micro

    Science.gov (United States)

    Petrantoni, M.; Rossi, C.; Salvagnac, L.; Conédéra, V.; Estève, A.; Tenailleau, C.; Alphonse, P.; Chabal, Y. J.

    2010-10-01

    Multilayered Al/CuO thermite was deposited by a dc reactive magnetron sputtering method. Pure Al and Cu targets were used in argon-oxygen gas mixture plasma and with an oxygen partial pressure of 0.13 Pa. The process was designed to produce low stress (<50 MPa) multilayered nanoenergetic material, each layer being in the range of tens nanometer to one micron. The reaction temperature and heat of reaction were measured using differential scanning calorimetry and thermal analysis to compare nanostructured layered materials to microstructured materials. For the nanostructured multilayers, all the energy is released before the Al melting point. In the case of the microstructured samples at least 2/3 of the energy is released at higher temperatures, between 1036 and 1356 K.

  11. 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.

  12. Al plasma jet formation via ion stream compression by surrounding low-Z plasma envelope

    OpenAIRE

    Pisarczyk T.; Kasperczuk A.; Chodukowski T.; Kalinowska Z.; Guskov S.Yu.; Demchenko N.N.; Renner O.; Krousky E.; Pfeifer M; Rohlena K.; Skala J.; Ullschmied J.; Klir D.; Kravarik J.; Kubes P.

    2013-01-01

    In our earlier papers it was demonstrated that the plasma pressure decreases with the growing atomic number of the target material. In this context a question arose about the possibility to collimate the Al plasma outflow by using the plastic plasma as a compressor. For that purpose a plastic target with an Al cylindrical insert of 400 μm in diameter was used. The experiment was carried out at the PALS laser facility. The laser provided a 250 ps (FWHM) pulse with the energy of 130 J at the th...

  13. 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...

  14. 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.

  15. 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.…

  16. 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

    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 str...

  17. Effect of Mn, Si, and Cooling Rate on the Formation of Iron-Rich Intermetallics in 206 Al-Cu Cast Alloys

    Science.gov (United States)

    Liu, K.; Cao, X.; Chen, X.-G.

    2012-10-01

    The solidification structures of commercial 206 Al-Cu cast alloys with 0.15 pct Fe have been studied using thermal analysis (TA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and electron backscattered diffraction (EBSD). The EBSD results have shown that there are two iron-rich intermetallics: Chinese script α-Fe and platelet-like β-Fe. The addition of either Mn or Si has helped to promote the formation of α-Fe and hinder the precipitate of β-Fe. The combined addition of both Mn and Si is even more effective than the individual addition of either Mn or Si. The full solidification sequence of the 206 cast alloy has been established. The volume percent and formation temperature increase for α-Fe but decrease for β-Fe with increasing cooling rate. The platelet β-Fe can be effectively suppressed in 206 cast alloys by controlling the alloy chemistry and cooling rate. A casting process map is proposed to correlate the Mn and Si contents with cooling rates for the 206 cast alloys.

  18. 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.

  19. Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

    Science.gov (United States)

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

    2016-05-01

    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 subsequent recrystallization occurred on the aluminum side of the interface.

  20. 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.

  1. 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.

  2. METHOD OF SUPPRESSING UAl$sub 4$ FORMATION IN U-Al ALLOYS

    Science.gov (United States)

    Picklesimer, M.L.; Thurber, W.C.

    1960-08-23

    A method is given for suppressing the formation of UAl/sub 4/ in uranium- - aluminum alloys, thereby rendering these alloys more easily workable. The method comprises incorporating in the base alloy a Group Four element selected from the group consisting of Si, Ti, Ge, Zr, and Sn, the addition preferably being within the range of 0.5to20at.%.

  3. Formation of non-equilibrium germanium-based solid solutions in al-ge-alloys

    Directory of Open Access Journals (Sweden)

    O.Yu. Bereza

    2012-08-01

    Full Text Available This article is devoted to the investigation of phase composition and microstructure of the higher cooled aluminum-germanium alloys. The formation of non-equilibrium germanium solid solutions is shown. The influence of the rate of cooling and the germanium percentage on the phase composition of alloys is shown.

  4. Trilobites from the Çal Tepe Formation (Cambrian), Near Seydişehir, Central Taurides, Southwestern Turkey

    OpenAIRE

    DEAN, WILLIAM T.

    2005-01-01

    The type section of the Çal Tepe Formation, near Seydişehir, is reviewed. The basal dolomite member is unfossiliferous, but the succeeding black limestone member (24 m), light-grey limestone member (10.15 m), and red nodular limestone member (46.7 m) are subdivided into thirty-seven numbered, often fossiliferous beds. Trilobites from the black limestone member, late Early Cambrian, exhibit affinities with Morocco, Spain and northwestern Europe; they include one new genus and species (Pamphyli...

  5. 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.

  6. An x-ray photoemission electron microscopy study of the formation of Ti-Al phases in 4 mol% TiCl{sub 3} catalyzed NaAlH{sub 4} during high energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Dobbins, Tabbetha; Uprety, Youaraj [Institute for Micromanufacturing, Louisiana Tech University, 911 Hergot Avenue, Ruston, LA 71272 (United States); Abrecht, Mike [Synchrotron Radiation Center, University of Wisconsin at Madison, 3731 Schneider Drive, Madison, WI 53789 (United States); Moore, Kristan [Department of Physics, Grambling State University, Grambling, LA 71245 (United States)

    2009-05-20

    This study reports reaction pathways to form TiAl{sub x} metallic complexes during the high energy ball milling of 4 mol% TiCl{sub 3} with NaAlH{sub 4} powders determined using local structure analysis of Ti{sup x+} and Al{sup x+} species. Using x-ray photoemission electron microscopy (XPEEM) and x-ray diffraction (XRD), the oxidation state of Al{sup x+} and Ti{sup x+} and the crystalline compounds existing in equilibrium with NaAlH{sub 4} were tracked for samples milled for times of 0 (i.e. mixing), 5, and 25 min. XPEEM analysis of the Al K edge after 5 min of milling reveals that Al remains in the 3+ oxidation state (i.e. in NaAlH{sub 4}) around Ti{sup 0}-rich regions of the sample. After 25 min of high energy milling, Ti{sup 0} has reacted with Al{sup 3+} (in nearby NaAlH{sub 4}) to form TiAl{sub x} complexes. This study reports the pathway for TiAl{sub x} complex formation during milling of 4 mol% TiCl{sub 3} catalyzed NaAlH{sub 4} to be as follows: (1) Ti{sup 3+} reduces to Ti{sup 0} (with Al{sup 3+} near Ti{sup 0} regions) and (2) Ti{sup 0} reacts with Al{sup 3+} in NaAlH{sub 4} to form TiAl{sub x} complexes.

  7. Phraseologismen als Quelle der Wortbildung. Phraseological units as source of word-formation

    Directory of Open Access Journals (Sweden)

    Olena Lazarenko

    2008-01-01

    Full Text Available Phraseological units are not only steady constructions, the transition of free word-combinations in semantically indivisible and syntactically entire word-combinations, but they also serve as a buil­ding material for new words.The article is devoted to the productivity of phraseological units in word-formation of the Ger­man language. The object of my research is 1200 lexemes motivated by phraseological units. The research material is extracted from lexical and phraseological dictionaries, the German belles-lettres and press. The purpose of this study is to analyse linguistic and extralinguistic factors causing the process of the dephraseological derivation, basic word-formation mechanisms and ways of enri­ching vocabulary on the basis of phraseological units.

  8. 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.

  9. 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.

  10. Promoting Effect of CeO2 Addition on Activity and Catalytic Stability in Steam Reforming of Methane over Ni/Al2O3

    International Nuclear Information System (INIS)

    Hydrogen production by steam reforming of methane was studied over Ni catalysts supported on CeO2, Al2O3 and CeO2-Al2O3. These catalysts were prepared using the impregnation method and characterized by XRD. The effect of CeO2 promoter on the catalytic performance of Ni/Al2O3 catalyst for methane steam reforming reaction was investigated. In fact, CeO2 had a positive effect on the catalytic activity in this reaction. Experimental results demonstrated that Ni/CeO2-Al2O3 catalyst showed excellent catalytic activity and high reaction performance. In addition, the effects of reaction temperature and metal content on the conversion of CH4 and H2/CO ratio were also investigated. Results indicated that CH4 conversion increased significantly with the increase of the reaction temperature and metal content. (author)

  11. ALS-associated TDP-43 induces endoplasmic reticulum stress, which drives cytoplasmic TDP-43 accumulation and stress granule formation.

    Directory of Open Access Journals (Sweden)

    Adam K Walker

    Full Text Available In amyotrophic lateral sclerosis (ALS and frontotemporal lobar degeneration, TAR DNA binding protein 43 (TDP-43 accumulates in the cytoplasm of affected neurons and glia, where it associates with stress granules (SGs and forms large inclusions. SGs form in response to cellular stress, including endoplasmic reticulum (ER stress, which is induced in both familial and sporadic forms of ALS. Here we demonstrate that pharmacological induction of ER stress causes TDP-43 to accumulate in the cytoplasm, where TDP-43 also associates with SGs. Furthermore, treatment with salubrinal, an inhibitor of dephosphorylation of eukaryotic initiation factor 2-α, a key modulator of ER stress, potentiates ER stress-mediated SG formation. Inclusions of C-terminal fragment TDP-43, reminiscent of disease-pathology, form in close association with ER and Golgi compartments, further indicating the involvement of ER dysfunction in TDP-43-associated disease. Consistent with this notion, over-expression of ALS-linked mutant TDP-43, and to a lesser extent wildtype TDP-43, triggers several ER stress pathways in neuroblastoma cells. Similarly, we found an interaction between the ER chaperone protein disulphide isomerase and TDP-43 in transfected cell lysates and in the spinal cords of mutant A315T TDP-43 transgenic mice. This study provides evidence for ER stress as a pathogenic pathway in TDP-43-mediated disease.

  12. Effect of Film Formation Potential on Passive Behavior of Ultra-Fine-Grained 1050 Al Alloy Fabricated via ARB Process

    Science.gov (United States)

    Fattah-alhosseini, A.; Gashti, S. O.; Keshavarz, M. K.

    2016-04-01

    In this work, the effect of film formation potential on the passive behavior of ultra-fine-grained 1050 Al alloy in a borate buffer solution is investigated. For this purpose, the specimens were fabricated via accumulative roll bonding (ARB) process up to 1, 3, 5, and 7 passes. To determine the evolution of microstructure as a function of ARB process, atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used. AFM images revealed that the grain size values decreased as the number of ARB passes increased. Moreover, TEM micrograph showed that mean grain size of the sample reached to about 340 nm after applying 7 passes of ARB. Potentiodynamic polarization plots indicated that, as the number of ARB passes increased, the corrosion and passive current densities decreased. Also, electrochemical impedance spectroscopy measurements showed that at selected applied potential above open circuit potential, the corrosion resistance of the 1050 Al alloy was systematically increased by applying further ARB passes. It was found that passive behavior of the ARBed 1050 Al alloy specimens were improved by reducing the grain size.

  13. 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...

  14. Kinetics of F center annealing and colloid formation in Al2O3

    Science.gov (United States)

    Kotomin, E. A.; Kuzovkov, V. N.; Popov, A. I.; Vila, R.

    2016-05-01

    The diffusion-controlled kinetics of the F center annealing in Al2O3 (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.

  15. 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.

  16. Methane formation from betaine with trimethylamine as intermediary. Methanbildung aus Betain ueber Trimethylamin als Zwischenprodukt

    Energy Technology Data Exchange (ETDEWEB)

    Naumann, E.

    1983-07-01

    A defined mixed culture of C-sporogenes and Methanoscarina barkeri of the Fusaro strain converted betaine into methane as the main fermentation product in the presence of an equal amount of L-alanine. Methane formation took place in two clearly distinct phases. In the first phase, the substrate mixture was completely converted by C. sporogenes, while the total trimethylamine plus 15.5% of the expected acetate was converted by M. barkeri, Fusaro strain. In the second phase, methane was formed exclusively from the remaining acetate. There was no syntrophic association between the two organisms.

  17. Effects of the Formation of Al x Cu y Gradient Interfaces on Mechanical Property of Steel/Al Laminated Sheets by Introducing Cu Binding-Sheets

    Science.gov (United States)

    Wei, Aili; Liu, Xinghai; Shi, Quanxin; Liang, Wei

    2015-07-01

    Steel/Cu/Al laminated sheets were fabricated by two-pass hot rolling to improve the mechanical properties of steel/Al sheets. The bonding properties and deformability of the steel/Cu/Al sheets were studied. Steel/Al and steel/Cu/Al samples were rolled at 350°C for 15 min with the first-pass reduction of 40%, and then heated at 600°C for 5 min with different reductions. It was found that the steel/Cu/Al samples rolled by the second-pass reduction of 85% could endure the maximum 90° bend cycle times of 45, exhibiting excellent fatigue resistance as well as deformability. The steel/Al samples could only reach the maximum 90° bend cycle times of 20. Furthermore, the scanning electron microscope, energy-dispersive spectrometer, and electron backscattered diffraction results showed that the preferred growth orientations of Cu, Al4Cu9, and Al2Cu on the steel/Cu/Al laminated sheets are {-1, 1, 2} , {1, 0, 0} and {-1, 1, 2} {1, 1, 0} . The orientation relationships between Cu and Al2Cu are {1, 1, 0}(fcc)//{1, 1, 0}(bct) and {1, 1, 1}(fcc)//{1, 1, 1}(bct). The improved bonding property and excellent fatigue resistance as well as deformability were mainly ascribed to the tight combination and consistent deformability across steel, Al, and the transition layers (Cu, Al4Cu9, and Al2Cu).

  18. CoREST1 promotes tumor formation and tumor stroma interactions in a mouse model of breast cancer.

    Directory of Open Access Journals (Sweden)

    Sohini Mazumdar

    Full Text Available Regulators of chromatin structure and gene expression contribute to tumor formation and progression. The co-repressor CoREST1 regulates the localization and activity of associated histone modifying enzymes including lysine specific demethylase 1 (LSD1 and histone deacetylase 1 (HDAC1. Although several CoREST1 associated proteins have been reported to enhance breast cancer progression, the role of CoREST1 in breast cancer is currently unclear. Here we report that knockdown of CoREST1 in the basal-type breast cancer cell line, MDA-MB-231, led to significantly reduced incidence and diminished size of tumors compared to controls in mouse xenograft studies. Notably, CoREST1-depleted cells gave rise to tumors with a marked decrease in angiogenesis. CoREST1 knockdown led to a decrease in secreted angiogenic and inflammatory factors, and mRNA analysis suggests that CoREST1 promotes expression of genes related to angiogenesis and inflammation including VEGF-A and CCL2. CoREST1 knockdown decreased the ability of MDA-MB-231 conditioned media to promote endothelial cell tube formation and migration. Further, tumors derived from CoREST1-depleted cells had reduced macrophage infiltration and the secretome of CoREST1 knockdown cells was deficient in promoting macrophage migration and macrophage-mediated angiogenesis. Taken together, these findings reveal that the epigenetic regulator CoREST1 promotes tumorigenesis in a breast cancer model at least in part through regulation of gene expression patterns in tumor cells that have profound non-cell autonomous effects on endothelial and inflammatory cells in the tumor microenvironment.

  19. 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.

  20. 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.

  1. 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.

  2. Control of mammalian cell mutagenesis and differentiation by chemicals which initiate or promote tumor formation

    Energy Technology Data Exchange (ETDEWEB)

    Jones, C. A.; Huberman, E.

    1980-01-01

    A cell-mediated mutagenesis assay was developed to predict the potential carcinogenic hazard of some environmental chemicals. In this assay, Chinese hamster V79 cells, which are susceptible to mutagenesis, are co-cultivated with cells capable of metabolizing chemical carcinogens. Use of this assay made it possible to demonstrate a relationship between the degree of carcinogenicity and mutagenicity of a series of polycyclic hydrocarbons and nitrosamines and to study the organ specificity exhibited by some chemical carcinogens. However, most short-term in vitro assays are designed to detect mutagenic activity and therefore do not detect tumor promoting agents which are devoid of this activity. By analyzing various markers of terminal differentiation in cultured human melanoma and myeloid leukemia cells, we have established a relationship between the activity of a series of tumor promoting phorbol diesters in the mouse skin and their ability to induce terminal differentiation. We suggest that measuring alterations in the differentiation characteristics of some cultured cells may represent an approach by which environmental tumor promoting agents can be studied and detected.

  3. Formation of out-burst structure in hot-dip Zn-5mass%Al alloy coating; Yoyu Zn-5mass%Al gokin mekki ni okeru tosshutsuso no keisei kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Y.; Ando, A.; Komatsu, A. [Nisshin Steel Co. Ltd., Tokyo (Japan); Yamakawa, K. [University of Osaka Prefecture, Osaka (Japan). College of Engineering

    1998-10-01

    The formation of the `out-burst` products which is consisted of Al-Fe intermetallic compounds (IMCs) grown locally and abnormally, has been studied to compare with the structure of thin alloy layer normally formed on the sheet steel in a hot-dip Zn-5mass% Al alloy coating at the bath temperature of 450degC. The formation of the out-burst products is not due to the localized growth of thin alloy layer consisted of mainly Zn containing Al3Fe(Al13Fe4), but due to the growth of Al-Fe IMCs with mainly Zn containing Al5Fe2 formed at ferrite grain boundaries near the steel surface. These Al-Fe IMCs are considered to be changed from Fe-Zn IMCs which have been formed by the grain boundary diffusion of Zn. And, during changing to Al-Fe IMCs, Zn discharged from Fe-Zn IMCs further diffuses to the adjacent ferrite grain boundaries and also into the adjacent ferrite grains. As a result, Fe-Zn IMCs are formed around Al-Fe IMCs which have been formed at the grain boundaries, and changes again to Al-Fe IMCs. This growth behavior of Al-Fe IMCs formed at the grain boundaries is induced from the results obtained in the previous works that the changing rate from Fe-Zn IMCs to Al-Fe IMCs in a molten Zn-5mass% Al alloy bath at 450degC is very high. 9 refs., 5 figs., 2 tabs.

  4. Erythorbic acid promoted formation of CdS QDs in a tube-in-tube micro-channel reactor

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yan; Tan, Jiawei; Wang, Jiexin; Chen, Jianfeng [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Sun, Baochang, E-mail: sunbc@mail.buct.edu.cn [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Shao, Lei, E-mail: shaol@mail.buct.edu.cn [State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China)

    2014-12-15

    Erythorbic acid assistant synthesis of CdS quantum dots (QDs) was conducted by homogeneous mixing of two continuous liquids in a high-throughput microporous tube-in-tube micro-channel reactor (MTMCR) at room temperature. The effects of the micropore size of the MTMCR, liquid flow rate, mixing time and reactant concentration on the size and size distribution of CdS QDs were investigated. It was found that the size and size distribution of CdS QDs could be tuned in the MTMCR. A combination of erythorbic acid promoted formation technique with the MTMCR may be a promising pathway for controllable mass production of QDs.

  5. 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

    2016-07-01

    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.

  6. 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.

  7. A Needs Assessment, Development, and Formative Evaluation of a Health Promotion Smartphone Application for College Students

    Science.gov (United States)

    Miller, Tiffany; Chandler, Laura; Mouttapa, Michele

    2015-01-01

    Background: Approximately half of college students who completed the National College Health Assessment 2013 indicated a greater need for health-related information. University-based smartphone applications may help students better access this information. Purpose: This study describes the needs assessment, development, and formative evaluation of…

  8. An Undergraduate Study of Two Transcription Factors that Promote Lateral Root Formation

    Science.gov (United States)

    Bargmann, Bastiaan O. R.; Birnbaum, Kenneth D.; Brenner, Eric D.

    2014-01-01

    We present a lab that enables students to test the role of genes involved in the regulation of lateral roots growth in the model plant "Arabidopsis thaliana." Here, students design an experiment that follows the effects of the hormone auxin on the stimulation of genes involved in the formation of lateral root initials. These genes, known…

  9. NRP1 Regulates CDC42 Activation to Promote Filopodia Formation in Endothelial Tip Cells

    Directory of Open Access Journals (Sweden)

    Alessandro Fantin

    2015-06-01

    Full Text Available Sprouting blood vessels are led by filopodia-studded endothelial tip cells that respond to angiogenic signals. Mosaic lineage tracing previously revealed that NRP1 is essential for tip cell function, although its mechanistic role in tip cells remains poorly defined. Here, we show that NRP1 is dispensable for genetic tip cell identity. Instead, we find that NRP1 is essential to form the filopodial bursts that distinguish tip cells morphologically from neighboring stalk cells, because it enables the extracellular matrix (ECM-induced activation of CDC42, a key regulator of filopodia formation. Accordingly, NRP1 knockdown and pharmacological CDC42 inhibition similarly impaired filopodia formation in vitro and in developing zebrafish in vivo. During mouse retinal angiogenesis, CDC42 inhibition impaired tip cell and vascular network formation, causing defects that resembled those due to loss of ECM-induced, but not VEGF-induced, NRP1 signaling. We conclude that NRP1 enables ECM-induced filopodia formation for tip cell function during sprouting angiogenesis.

  10. Lipid oxidation promotes acrylamide formation in fat-rich model systems

    NARCIS (Netherlands)

    Capuano, E.; Oliviero, T.; Açar, Ö.; Gökmen, V.; Fogliano, V.

    2010-01-01

    Lipid oxidation is one of the major chemical reactions occurring during food processing or storage and may have a strong impact on the final quality of foods. A significant role of carbonyl compounds derived from lipid oxidation in acrylamide formation has been recently proposed. In this work, the e

  11. 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.

  12. 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

    2015-08-01

    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.

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

    International Nuclear Information System (INIS)

    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

  14. 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

  15. Shu proteins promote the formation of homologous recombination intermediates that are processed by Sgs1-Rmi1-Top3

    DEFF Research Database (Denmark)

    Mankouri, Hocine W; Ngo, Hien-Ping; Hickson, Ian D

    2007-01-01

    CSM2, PSY3, SHU1, and SHU2 (collectively referred to as the SHU genes) were identified in Saccharomyces cerevisiae as four genes in the same epistasis group that suppress various sgs1 and top3 mutant phenotypes when mutated. Although the SHU genes have been implicated in homologous recombination...... formation of MMS-induced HRR intermediates (X-molecules) arising during replication in sgs1 cells, mutation of SHU genes attenuated the level of these structures. Similar findings were also observed in shu1 cells in which Rmi1 or Top3 function was impaired. We propose a model in which the Shu proteins act...... in HRR to promote the formation of HRR intermediates that are processed by the Sgs1-Rmi1-Top3 complex....

  16. An x-ray photoemission electron microscopy study of the formation of Ti-Al phases in 4 mol% TiCl3 catalyzed NaAlH4 during high energy ball milling

    Science.gov (United States)

    Dobbins, Tabbetha; Abrecht, Mike; Uprety, Youaraj; Moore, Kristan

    2009-05-01

    This study reports reaction pathways to form TiAlx metallic complexes during the high energy ball milling of 4 mol% TiCl3 with NaAlH4 powders determined using local structure analysis of Tix+ and Alx+ species. Using x-ray photoemission electron microscopy (XPEEM) and x-ray diffraction (XRD), the oxidation state of Alx+ and Tix+ and the crystalline compounds existing in equilibrium with NaAlH4 were tracked for samples milled for times of 0 (i.e. mixing), 5, and 25 min. XPEEM analysis of the Al K edge after 5 min of milling reveals that Al remains in the 3+ oxidation state (i.e. in NaAlH4) around Ti0-rich regions of the sample. After 25 min of high energy milling, Ti0 has reacted with Al3+ (in nearby NaAlH4) to form TiAlx complexes. This study reports the pathway for TiAlx complex formation during milling of 4 mol% TiCl3 catalyzed NaAlH4 to be as follows: (1) Ti3+ reduces to Ti0 (with Al3+ near Ti0 regions) and (2) Ti0 reacts with Al3+ in NaAlH4 to form TiAlx complexes.

  17. Promotion effect of iron on Mo/Al2O3 catalyst for the CAMERE process

    OpenAIRE

    Abolfazl Gharibi Kharaji; Ahmad Shariati

    2012-01-01

    Reverse Water Gas Shift (RWGS) reaction is one of the main reactions that can be used toreduce greenhouse gases emissions. Through this reaction CO2 is converted to CO to produce beneficialchemicals such as methanol. In this paper Mo-Al2O3 catalyst was prepared and then promoted with Feions through co-impregnation method to produce Fe-Mo-Al2O3 catalyst. XRD tests were taken todetermine the structure of the catalysts. Activity, selectivity and stability of both catalysts wereinvestigated in a ...

  18. In situ synchrotron x-ray characterization of microstructure formation in solidification processing of Al-based metallic alloys

    International Nuclear Information System (INIS)

    The microstructure formed during the solidification step has a major influence on the properties of materials processed by major techniques (casting, welding ...). In situ and real-time characterization by synchrotron X-ray imaging is the method of choice to unveil the dynamical formation of the solidification microstructure in metallic alloys, and thus provide precise data for the critical validation of the theoretical predictions that is needed for sound advancement of modeling and numerical simulation. After a description of the experimental procedure used at the European Synchrotron Radiation Facility (ESRF), dynamical phenomena in the formation of the grain structure and dendritic or equiaxed solidification microstructure in Al-based alloys are presented. Beyond fluid flow interaction, earth gravity induces stresses, deformation and fragmentation in the dendritic mush. Settling of dendrite arms and equiaxed grains thus occurs, in particular in the columnar to equiaxed transition. Other types of stresses and strains are caused by the mere formation of the solidification microstructure itself. In white-beam X-ray topography, stresses and strains are manifested by specific contrasts and breaking of the Laue images into several pieces. Finally, quantitative analysis of the grey level in radiographs enables the analysis of solute segregation, which noticeably results in solutal poisoning of growth when equiaxed grains are interacting. (author)

  19. Effect of Laser Processing Parameters on the Formation of Intermetallic Compounds in Fe-Al Dissimilar Welding

    Science.gov (United States)

    Meco, Sonia; Ganguly, Supriyo; Williams, Stewart; McPherson, Norman

    2014-09-01

    Fusion welding of steel to aluminum is difficult due to formation of different types of Fe-Al intermetallics (IMs). In this work, 2 mm-thick steel was joined to 6 mm aluminum in overlap configuration using a 8 kW CW fiber laser. A defocused laser beam was used to control the energy input and allow melting of the aluminum alone and form the bond by wetting of the steel substrate. Experimentally, the process energy was varied by changing the power density (PD) and interaction time separately to understand the influence of each of these parameters on the IM formation. It was observed that the IM formation is a complex function of PD and interaction time. It was also found that the mechanical strength of such joint could not be simply correlated to the IM layer thickness but also depends on the area of wetting of the steel substrate by molten aluminum. In order to form a viable joint, PD needs to be over a threshold value where although IM growth will increase, the strength will be better due to increased wetting. Any increase in interaction time, with PD over the threshold, will have negative effect on the bond strength.

  20. Formation of nanostructure and mechanical properties of cold-rolled Ti-15V-3Sn-3Al-3Cr alloy

    International Nuclear Information System (INIS)

    Microstructure evolution and mechanical properties of severe cold-rolled Ti-15V-3Sn-3Al-3Cr Ti-15-3 alloy were investigated and the formation of nanostructure was analysed by optical microscopy and transmission electron microscopy. Results show that fibrous microstructure with nanograins of below 100 nm is formed in the sheet of Ti-15-3 alloy with total thickness reduction of 80% by three passes cold rolling. The formation of nanostructure may be divided into three steps, firstly, formation of partial shear bands due to plastic instability; secondly, the crossing and refining of shear bands of different direction within the banded structure; thirdly, the forming of fibrous microstructure with nanograins. After three passes cold rolling and aging at 450 for 4 h, the ultimate strength of alloy can be increased to 1562 MPa. The strengthening of the alloy after aging mainly results from the abundant nucleation of nano-scaled α phase precipitated from the nano-sized β matrix.

  1. Mechanism of phase formation during quenching in the Al-Ga system

    Energy Technology Data Exchange (ETDEWEB)

    Savich, V.I.

    1988-12-01

    Through an evaluation of the bond energy in eutectic and metastable phases of different crystallographic structures but the same composition in the aluminum-gallium system, an explanation is given of the mechanism of phase formation in this and other eutectic systems during quenching. It is shown that a metastable phase is formed in this system from the liquid, where preferred interaction between different atomic species should be expected to occur in the melt. An explanation is also given for the nonoccurrence of the expected expansion of the region of the solid solution based on aluminium above 65% (at.) gallium during ultra rapid cooling of the liquid. Finally, an explanation is offered for the well-known empirical fact that most metastable phases formed during quenching are formed in the region of eutectic or near-eutectic compositions.

  2. 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

    2016-05-01

    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.

  3. 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.

  4. 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.

  5. 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.

  6. Biosurfactant as a Promoter of Methane Hydrate Formation: Thermodynamic and Kinetic Studies

    OpenAIRE

    Amit Arora; Swaranjit Singh Cameotra; Rajnish Kumar; Chandrajit Balomajumder; Anil Kumar Singh; Santhakumari, B.; Pushpendra Kumar; Sukumar Laik

    2016-01-01

    Natural gas hydrates (NGHs) are solid non-stoichiometric compounds often regarded as a next generation energy source. Successful commercialization of NGH is curtailed by lack of efficient and safe technology for generation, dissociation, storage and transportation. The present work studied the influence of environment compatible biosurfactant on gas hydrate formation. Biosurfactant was produced by Pseudomonas aeruginosa strain A11 and was characterized as rhamnolipids. Purified rhamnolipids r...

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

    Directory of Open Access Journals (Sweden)

    J. F. Hamilton

    2009-02-01

    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. Thrombospondin 1 promotes synaptic formation in bone marrow-derived neuron-like cells★

    OpenAIRE

    Huang, Yun; Lu, Mingnan; Guo, Weitao; Zeng, Rong; Wang, Bin; Wang, Huaibo

    2013-01-01

    In this study, a combination of growth factors was used to induce bone marrow mesenchymal stem cells differentiation into neuron-like cells, in a broader attempt to observe the role of thrombospondin 1 in synapse formation. Results showed that there was no significant difference in the differentiation rate of neuron-like cells between bone marrow mesenchymal stem cells with thrombospondin induction and those without. However, the cell shape was more complex and the neurites were dendritic, wi...

  9. 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.

  10. ADAM17-mediated CD44 cleavage promotes orasphere formation or stemness and tumorigenesis in HNSCC

    International Nuclear Information System (INIS)

    CD44, an extracellular matrix (ECM) receptor, has been described as a cancer stem cell marker in multiple cancers, including head and neck squamous cell carcinoma (HNSCC). HNSCC orasphere formation or stemness was characterized by cleavage of CD44, and thus we hypothesized that this proteolytic processing may be critical to stemness and tumorigenesis. We tested this hypothesis by examining the mechanisms that regulate this process in vitro and in vivo, and by exploring its clinical relevance in human specimens. Sphere assays have been used to evaluate stemness in vitro. Spheres comprised of HNSCC cells or oraspheres and an oral cancer mouse model were used to examine the significance of CD44 cleavage using stable suppression and inhibition approaches. These mechanisms were also examined in HNSCC specimens. Oraspheres exhibited increased levels of CD44 cleavage compared to their adherent counterparts. Given that disintegrin and metalloproteinase domain-containing protein 17 (ADAM17) is a major matrix metalloproteinase known to cleave CD44, we chemically inhibited and stably suppressed ADAM17 expression in HNSCC cells and found that these treatments blocked CD44 cleavage and abrogated orasphere formation. Furthermore, stable suppression of ADAM17 in HNSCC cells also diminished tumorigenesis in an oral cancer mouse model. Consistently, stable suppression of CD44 in HNSCC cells abrogated orasphere formation and inhibited tumorigenesis in vivo. The clinical relevance of these findings was confirmed in matched primary and metastatic human HNSCC specimens, which exhibited increased levels of ADAM17 expression and concomitant CD44 cleavage compared to controls. CD44 cleavage by ADAM17 is critical to orasphere formation or stemness and HNSCC tumorigenesis

  11. 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.

  12. 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

  13. SOD1 oxidation and formation of soluble aggregates in yeast: Relevance to sporadic ALS development

    Directory of Open Access Journals (Sweden)

    Dorival Martins

    2014-01-01

    Full Text Available Misfolding and aggregation of copper–zinc superoxide dismutase (Sod1 are observed in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS. Mutations in Sod1 lead to familial ALS (FALS, which is a late-onset disease. Since oxidative damage to proteins increases with age, it had been proposed that oxidation of Sod1 mutants may trigger their misfolding and aggregation in FALS. However, over 90% of ALS cases are sporadic (SALS with no obvious genetic component. We hypothesized that oxidation could also trigger the misfolding and aggregation of wild-type Sod1 and sought to confirm this in a cellular environment. Using quiescent, stationary-phase yeast cells as a model for non-dividing motor neurons, we probed for post-translational modification (PTM and aggregation of wild-type Sod1 extracted from these cells. By size-exclusion chromatography (SEC, we isolated two populations of Sod1 from yeast: a low-molecular weight (LMW fraction that is catalytically active and a catalytically inactive, high-molecular weight (HMW fraction. High-resolution mass spectrometric analysis revealed that LMW Sod1 displays no PTMs but HMW Sod1 is oxidized at Cys146 and His71, two critical residues for the stability and folding of the enzyme. HMW Sod1 is also oxidized at His120, a copper ligand, which will promote loss of this catalytic metal cofactor essential for SOD activity. Monitoring the fluorescence of a Sod1-green-fluorescent-protein fusion (Sod1-GFP extracted from yeast chromosomally expressing this fusion, we find that HMW Sod1-GFP levels increase up to 40-fold in old cells. Thus, we speculate that increased misfolding and inclusion into soluble aggregates is a consequence of elevated oxidative modifications of wild-type Sod1 as cells age. Our observations argue that oxidative damage to wild-type Sod1 initiates the protein misfolding mechanisms that give rise to SALS.

  14. Efficiently engineered cell sheet using a complex of polyethylenimine–alginate nanocomposites plus bone morphogenetic protein 2 gene to promote new bone formation

    Directory of Open Access Journals (Sweden)

    Jin H

    2014-05-01

    Full Text Available Han Jin,1 Kai Zhang,2 Chunyan Qiao,1 Anliang Yuan,1 Daowei Li,1 Liang Zhao,1 Ce Shi,1 Xiaowei Xu,1 Shilei Ni,1 Changyu Zheng,3 Xiaohua Liu,4 Bai Yang,2 Hongchen Sun11Department of Pathology, School of Stomatology, Jilin University, Changchun, People’s Republic of China; 2State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, People’s Republic of China; 3Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA; 4Department of Biomedical Sciences, Texas A&M University Baylor College of Dentistry, Dallas, TX, USAAbstract: Regeneration of large bone defects is a common clinical problem. Recently, stem cell sheet has been an emerging strategy in bone tissue engineering. To enhance the osteogenic potential of stem cell sheet, we fabricated bone morphogenetic protein 2 (BMP-2 gene-engineered cell sheet using a complex of polyethylenimine–alginate (PEI–al nanocomposites plus human BMP-2 complementary(cDNA plasmid, and studied its osteogenesis in vitro and in vivo. PEI–al nanocomposites carrying BMP-2 gene could efficiently transfect bone marrow mesenchymal stem cells. The cell sheet was made by culturing the cells in medium containing vitamin C for 10 days. Assays on the cell culture showed that the genetically engineered cells released the BMP-2 for at least 14 days. The expression of osteogenesis-related gene was increased, which demonstrated that released BMP-2 could effectively induce the cell sheet osteogenic differentiation in vitro. To further test the osteogenic potential of the cell sheet in vivo, enhanced green fluorescent protein or BMP-2-producing cell sheets were treated on the cranial bone defects. The results indicated that the BMP-2-producing cell sheet group was more efficient than other groups in promoting bone formation in the defect area. Our results suggested that PEI–al

  15. Adhesion- and Degranulation-Promoting Adapter Protein Promotes CD8 T Cell Differentiation and Resident Memory Formation and Function during an Acute Infection.

    Science.gov (United States)

    Fiege, Jessica K; Beura, Lalit K; Burbach, Brandon J; Shimizu, Yoji

    2016-09-15

    During acute infections, naive Ag-specific CD8 T cells are activated and differentiate into effector T cells, most of which undergo contraction after pathogen clearance. A small population of CD8 T cells persists as memory to protect against future infections. We investigated the role of adhesion- and degranulation-promoting adapter protein (ADAP) in promoting CD8 T cell responses to a systemic infection. Naive Ag-specific CD8 T cells lacking ADAP exhibited a modest expansion defect early after Listeria monocytogenes or vesicular stomatitis virus infection but comparable cytolytic function at the peak of response. However, reduced numbers of ADAP-deficient CD8 T cells were present in the spleen after the peak of the response. ADAP deficiency resulted in a greater frequency of CD127(+) CD8 memory precursors in secondary lymphoid organs during the contraction phase. Reduced numbers of ADAP-deficient killer cell lectin-like receptor G1(-) CD8 resident memory T (TRM) cell precursors were present in a variety of nonlymphoid tissues at the peak of the immune response, and consequently the total numbers of ADAP-deficient TRM cells were reduced at memory time points. TRM cells that did form in the absence of ADAP were defective in effector molecule expression. ADAP-deficient TRM cells exhibited impaired effector function after Ag rechallenge, correlating with defects in their ability to form T cell-APC conjugates. However, ADAP-deficient TRM cells responded to TGF-β signals and recruited circulating memory CD8 T cells. Thus, ADAP regulates CD8 T cell differentiation events following acute pathogen challenge that are critical for the formation and selected functions of TRM cells in nonlymphoid tissues. PMID:27521337

  16. 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.

  17. 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.

  18. Friedel's salt formation in sulfoaluminate cements: A combined XRD and {sup 27}Al MAS NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Paul, G. [Dipartimento di Scienze ed Innovazione Tecnologica, Università del Piemonte Orientale A. Avogadro, Viale T. Michel 11, 15121 Alessandria (Italy); Boccaleri, E., E-mail: enrico.boccaleri@mfn.unipmn.it [Dipartimento di Scienze ed Innovazione Tecnologica, Università del Piemonte Orientale A. Avogadro, Viale T. Michel 11, 15121 Alessandria (Italy); Buzzi, L.; Canonico, F. [Buzzi Unicem S.p.A., Via L. Buzzi 6, 15033 Casale Monferrato (Italy); Gastaldi, D., E-mail: dgastaldi@buzziunicem.it [Buzzi Unicem S.p.A., Via L. Buzzi 6, 15033 Casale Monferrato (Italy)

    2015-01-15

    Four different binders based on calcium sulfoaluminate cements have been submitted to accelerated chlorination through ionic exchange on hydrated pastes, in order to investigate their ability to chemically bind chloride ions that might reduce chloride penetration. The composition of hydrated cements before and after the treatment was evaluated by means of an X-Ray Diffraction–{sup 27}Al Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy combined study, allowing to take into account even partially amorphous phases and to make quantitative assumption on the relative abundance of the different aluminium-containing phases. It was found that low SO{sub 3} Sulfoaluminate–Portland ternary systems are the most effective in binding chloride ions and the active role played by different members of the AFm family in chloride uptake was confirmed. Moreover, a peculiar behavior related to the formation of Friedel's salt in different pH conditions was also established for the different cements.

  19. On the formation of recrystallization textures in binary Al-1.3% Mn investigated by means of local texture analysis

    Energy Technology Data Exchange (ETDEWEB)

    Engler, O.; Yang, P.; Kong, X.W. [RWTH Aachen (Germany). Inst. fuer Metallkunde und Metallphysik

    1996-08-01

    The development of the recrystallization textures of high purity Al-1.3% Mn is analyzed with dependence on the degree of deformation, the annealing temperature and, particularly, the precipitation state prior to deformation. Besides X-ray macrotexture analysis, local orientation measurements by electron diffraction in a SEM (EBSD) and in a TEM (MBED) are applied. A combination of these three techniques permits orientation determination with increasing spatial resolution and yields a much more fundamental understanding about the underlying recrystallization mechanisms than is possible using solely one of these techniques. The recrystallization textures are characterized by a competition between cube-oriented grains which nucleate at band-like structures and grains due to particle stimulated nucleation (PSN). The evolution of the resulting textures is discussed in terms of formation and subsequent growth of the recrystallization nuclei.

  20. 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.

  1. 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.

  2. 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...... dioxide (CO2), with 5.0mole percent THF in the initial aqueous phase, are presented in the temperature range from 283.3K to 285.2K. At 283.3K, the three-phase equilibrium pressure is determined to be 0.61MPa (absolute pressure).Four-phase hydrate (H)-aqueous liquid (Lw)-organic liquid (La)-vapour (V....... 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....

  3. 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.

  4. 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.

  5. 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.

  6. Cube texture formation during the early stages of recrystallization of Al-1%wt.Mn and AA1050 aluminium alloys

    Science.gov (United States)

    Miszczyk, M. M.; Paul, H.

    2015-08-01

    The cube texture formation during primary recrystallization was analysed in plane strain deformed samples of a commercial AA1050 alloy and an Al-1%wt.Mn model alloy single crystal of the Goss{110} orientation. The textures were measured with the use of X-ray diffraction and scanning electron microscopy equipped with an electron backscattered diffraction facility. After recrystallization of the Al-1%wt.Mn single crystal, the texture of the recrystallized grains was dominated by four variants of the S{123} orientation. The cube grains were only sporadically detected by the SEM/EBSD system. Nevertheless, an increased density of poles corresponding to the cube orientation was observed. The latter was connected with the superposition of four variants of the S{123} orientation. This indicates that the cube texture after the recrystallization was a ‘compromise texture’. In the case of the recrystallized AA1050 alloy, the strong cube texture results from both the increased density of the particular poles of the four variants of the S orientation and the ∼40°(∼)-type rotation. The first mechanism transforms the Sdef-oriented areas into Srex ones, whereas the second the near S-oriented, as-deformed areas into near cube-oriented grains.

  7. 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.

  8. 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. PMID:27362920

  9. Resveratrol inhibits myeloma cell growth, prevents osteoclast formation, and promotes osteoblast differentiation

    DEFF Research Database (Denmark)

    Boissy, Patrice; Andersen, Thomas L; Abdallah, Basem M;

    2005-01-01

    Multiple myeloma is characterized by the accumulation of clonal malignant plasma cells in the bone marrow, which stimulates bone destruction by osteoclasts and reduces bone formation by osteoblasts. In turn, the changed bone microenvironment sustains survival of myeloma cells. Therefore......, a challenge for treating multiple myeloma is discovering drugs targeting not only myeloma cells but also osteoclasts and osteoblasts. Because resveratrol (trans-3,4',5-trihydroxystilbene) is reported to display antitumor activities on a variety of human cancer cells, we investigated the effects...... of this natural compound on myeloma and bone cells. We found that resveratrol reduces dose-dependently the growth of myeloma cell lines (RPMI 8226 and OPM-2) by a mechanism involving cell apoptosis. In cultures of human primary monocytes, resveratrol inhibits dose-dependently receptor activator of nuclear factor...

  10. 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.

  11. {gamma}-Al{sub 2}O{sub 3} thin film formation via oxidation of {beta}-NiAl(1 1 0)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhongfan, E-mail: zhangzhongfan@gmail.com [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Li Long; Yang, Judith C. [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

    2011-09-15

    {beta}-NiAl(1 1 0) was oxidized in air for 1-2 h in the temperature range of 650-950 deg. C. The structure and morphology of the oxide films were characterized using a cross-sectional transmission electron microscopy (TEM) method. Only a thin film of aluminum oxide, {gamma}-Al{sub 2}O{sub 3}, was formed. The epitaxial relationship between NiAl and {gamma}-Al{sub 2}O{sub 3} as well as the surface roughness depends on the oxidation temperature. The Nishiyama-Wassermann (NW) orientation relation (OR) between {beta}-NiAl and {gamma}-Al{sub 2}O{sub 3} was noted at an oxidation temperature of 850 deg. C while the Kurdjumov-Sachs (KS) OR was observed at 650 deg. C. The changes in the epitaxial relationship between the {gamma}-Al{sub 2}O{sub 3} film and the NiAl substrate were caused by lattice mismatch-induced strain energy during oxide growth. It was also noted that short time oxidation at T = 750 deg. C created {gamma}' phase precipitates between the NiAl substrate and the {gamma}-Al{sub 2}O{sub 3} film, while oxidation at the higher temperature of 950 deg. C resulted in textured polycrystalline {gamma}-Al{sub 2}O{sub 3} films. The smoothest single crystal epitaxial {gamma}-Al{sub 2}O{sub 3} film formed at an oxidation temperature of 850 deg. C in air.

  12. 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.

  13. Monocytes induce STAT3 activation in human mesenchymal stem cells to promote osteoblast formation.

    Directory of Open Access Journals (Sweden)

    Vicky Nicolaidou

    Full Text Available A major therapeutic challenge is how to replace bone once it is lost. Bone loss is a characteristic of chronic inflammatory and degenerative diseases such as rheumatoid arthritis and osteoporosis. Cells and cytokines of the immune system are known to regulate bone turnover by controlling the differentiation and activity of osteoclasts, the bone resorbing cells. However, less is known about the regulation of osteoblasts (OB, the bone forming cells. This study aimed to investigate whether immune cells also regulate OB differentiation. Using in vitro cell cultures of human bone marrow-derived mesenchymal stem cells (MSC, it was shown that monocytes/macrophages potently induced MSC differentiation into OBs. This was evident by increased alkaline phosphatase (ALP after 7 days and the formation of mineralised bone nodules at 21 days. This monocyte-induced osteogenic effect was mediated by cell contact with MSCs leading to the production of soluble factor(s by the monocytes. As a consequence of these interactions we observed a rapid activation of STAT3 in the MSCs. Gene profiling of STAT3 constitutively active (STAT3C infected MSCs using Illumina whole human genome arrays showed that Runx2 and ALP were up-regulated whilst DKK1 was down-regulated in response to STAT3 signalling. STAT3C also led to the up-regulation of the oncostatin M (OSM and LIF receptors. In the co-cultures, OSM that was produced by monocytes activated STAT3 in MSCs, and neutralising antibodies to OSM reduced ALP by 50%. These data indicate that OSM, in conjunction with other mediators, can drive MSC differentiation into OB. This study establishes a role for monocyte/macrophages as critical regulators of osteogenic differentiation via OSM production and the induction of STAT3 signalling in MSCs. Inducing the local activation of STAT3 in bone cells may be a valuable tool to increase bone formation in osteoporosis and arthritis, and in localised bone remodelling during fracture repair.

  14. MAX phase formation by intercalation upon annealing of TiC{sub x}/Al (0.4 {<=} x {<=} 1) bilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abdulkadhim, Ahmed; Takahashi, Tetsuya [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 10, 52074 Aachen (Germany); Music, Denis, E-mail: music@mch.rwth-aachen.de [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 10, 52074 Aachen (Germany); Munnik, Frans [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden (Germany); Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, Kopernikusstrasse 10, 52074 Aachen (Germany)

    2011-09-15

    TiC{sub x}/Al bilayer thin films were synthesized using combinatorial magnetron sputtering to study the influence of C content on the reaction products at different annealing temperatures. Based on energy-dispersive X-ray analysis calibrated by elastic recoil detection analysis data, x in TiC{sub x} was varied from 0.4 to 1.0. Film constitution was studied by X-ray diffraction before and after annealing at temperatures from 500 to 1000 deg. C. The formation of TiC{sub x} and Al in the as-deposited samples over the whole C/Ti range was identified. Upon annealing, TiC{sub x} reacts with Al to form Ti-Al-based intermetallics. At temperatures as low as 700 deg. C, the formation of MAX phases (space group P6{sub 3}/mmc) is observed at x {<=} 0.7. Based on the comparison between the C content induced changes in the lattice spacing of TiC{sub x} and Ti{sub 2}AlC as well as Ti{sub 3}AlC{sub 2}, we infer the direct formation of MAX phases by Al intercalation into TiC{sub x} for x {<=} 0.7.

  15. 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.

  16. 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.

  17. 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.

  18. The 'balance intervention' for promoting caloric compensatory behaviours in response to overeating: a formative evaluation.

    Science.gov (United States)

    Wammes, Birgitte; Breedveld, Boudewijn; Kremers, Stef; Brug, Johannes

    2006-08-01

    To help people prevent weight gain, the Netherlands Nutrition Centre initiated the 'balance intervention', which promotes moderation of food intake and/or increased physical activity in response to occasions of overeating. The aim of this study was to determine whether intervention materials were appreciated, encouraged information seeking and increased motivation and caloric compensatory behaviours. A three-group randomized trial with pre-intervention measures (n = 963, response 86%) and post-intervention measures (n = 857) using electronic questionnaires was conducted among participants aged 25-40 years, recruited from an Internet research panel. The first group received a printed brochure and electronic newsletters (print group), the second group was exposed to radio advertisements (radio group) and the third group was the control group. Multiple regression analyses were used to investigate the impact of the materials on self-reported prevalence of overeating, attitudes, perceived behavioural control, intentions and compensatory behaviours. At follow-up, we found significantly more positive attitudes, intentions and dietary action in the print and radio groups. However, participants who received the radio advertisement had a significantly lower perceived behavioural control. No effects were found on the prevalence of overeating. The results indicate that the intervention materials have potential for increasing people's attitudes, motivation and self-reported behaviour actions, with a possible negative side-effect on perceived behavioural control. PMID:16606638

  19. 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.

  20. 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.

  1. 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

  2. Understanding the Microstructure Formation of Ti-6Al-4V During Direct Laser Deposition via In-Situ Thermal Monitoring

    Science.gov (United States)

    Marshall, Garrett J.; Young, W. Joseph; Thompson, Scott M.; Shamsaei, Nima; Daniewicz, Steve R.; Shao, Shuai

    2016-03-01

    Understanding the thermal phenomena associated with direct laser deposition (DLD) is an important step toward obtaining `process-property-performance' relationships for various designed parts and materials, as well as achieving increased process control for meeting application constraints. In this study, a thermally monitored laser engineered net shaping (LENS™) system was used with time-invariant (uncontrolled) build parameters to construct Ti-6Al-4V cylinders. During fabrication, the part's thermal history and melt pool temperature were recorded via an in-chamber infrared camera and a dual-wavelength pyrometer, respectively. These tools demonstrate the use of non-destructive thermographic inspection for ensuring target part quality and/or microstructure. For the chosen part geometry, the melt pool was found to be approximately 40%-50% superheated during DLD, reaching temperatures as high as 2500°C. Temperature gradients varied and peaked around 1000°C/mm along the diameter of the relatively small cylinders. Cooling rates within the melt pool were found to increase as maximum melt pool temperature increased, for instance, from 12,000°C/s to 25,000°C/s. The post-DLD Ti-6Al-4V microstructure was found to vary from columnar near the substrate, or substrate-affected zone, to equiaxed approximately 2-3 mm from the substrate. Bulk heating of the part due to successive layer deposits was shown to promote α″ to an α + β decomposition, while prior- β grains were observed near and far from the substrate.

  3. 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.

  4. 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.

  5. 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.

  6. The formation mechanism and photocatalytic activity of hierarchical NiAl-LDH films on an Al substrate prepared under acidic conditions.

    Science.gov (United States)

    Xue, Li; Cheng, Yingzhi; Sun, Xiuyu; Zhou, Ziyan; Xiao, Xiaoling; Hu, Zhongbo; Liu, Xiangfeng

    2014-03-01

    NiAl-LDH films with hierarchical morphology have been fabricated by immersion of an Al substrate in Ni(2+)-containing solutions under strong acidic conditions, and the growth processes of the films are discussed in this communication. The as-prepared LDH films exhibit high activity in the photocatalytic degradation of organic contaminants. PMID:24445754

  7. 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.

  8. 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

  9. 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.

  10. Tau and spectraplakins promote synapse formation and maintenance through Jun kinase and neuronal trafficking

    Science.gov (United States)

    Voelzmann, Andre; Okenve-Ramos, Pilar; Qu, Yue; Chojnowska-Monga, Monika; del Caño-Espinel, Manuela; Prokop, Andreas; Sanchez-Soriano, Natalia

    2016-01-01

    The mechanisms regulating synapse numbers during development and ageing are essential for normal brain function and closely linked to brain disorders including dementias. Using Drosophila, we demonstrate roles of the microtubule-associated protein Tau in regulating synapse numbers, thus unravelling an important cellular requirement of normal Tau. In this context, we find that Tau displays a strong functional overlap with microtubule-binding spectraplakins, establishing new links between two different neurodegenerative factors. Tau and the spectraplakin Short Stop act upstream of a three-step regulatory cascade ensuring adequate delivery of synaptic proteins. This cascade involves microtubule stability as the initial trigger, JNK signalling as the central mediator, and kinesin-3 mediated axonal transport as the key effector. This cascade acts during development (synapse formation) and ageing (synapse maintenance) alike. Therefore, our findings suggest novel explanations for intellectual disability in Tau deficient individuals, as well as early synapse loss in dementias including Alzheimer’s disease. DOI: http://dx.doi.org/10.7554/eLife.14694.001 PMID:27501441

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Monitoring DNA triplex formation using multicolor fluorescence and application to insulin-like growth factor I promoter downregulation.

    Science.gov (United States)

    Hégarat, Nadia; Novopashina, Darya; Fokina, Alesya A; Boutorine, Alexandre S; Venyaminova, Alya G; Praseuth, Danièle; François, Jean-Christophe

    2014-03-01

    Inhibition of insulin-like growth factor I (IGF-I) signaling is a promising antitumor strategy and nucleic acid-based approaches have been investigated to target genes in the pathway. Here, we sought to modulate IGF-I transcriptional activity using triple helix formation. The IGF-I P1 promoter contains a purine/pyrimidine (R/Y) sequence that is pivotal for transcription as determined by deletion analysis and can be targeted with a triplex-forming oligonucleotide (TFO). We designed modified purine- and pyrimidine-rich TFOs to bind to the R/Y sequence. To monitor TFO binding, we developed a fluorescence-based gel-retardation assay that allowed independent detection of each strand in three-stranded complexes using end-labeling with Alexa 488, cyanine (Cy)3 and Cy5 fluorochromes. We characterized TFOs for their ability to inhibit restriction enzyme activity, compete with DNA-binding proteins and inhibit IGF-I transcription in reporter assays. TFOs containing modified nucleobases, 5-methyl-2'-deoxycytidine and 5-propynyl-2'-deoxyuridine, specifically inhibited restriction enzyme cleavage and formed triplexes on the P1 promoter fragment. In cells, deletion of the R/Y-rich sequence led to 48% transcriptional inhibition of a reporter gene. Transfection with TFOs inhibited reporter gene activity to a similar extent, whereas transcription from a mutant construct with an interrupted R/Y region was unaffected, strongly suggesting the involvement of triplex formation in the inhibitory mechanisms. Our results indicate that nuclease-resistant TFOs will likely inhibit endogenous IGF-I gene function in cells. PMID:24423253

  17. Characterization of Nano-structured Nickel Aluminate Formation During Mechanochemical Recycling of Spent NiO/ Al2O3 Catalyst

    International Nuclear Information System (INIS)

    In this research, use of mechanical alloying method, as a new and effective route for the recycling of spent NiO/ Al2O3 catalyst to nano-structured nickel aluminate spinel was investigated. It was found that the formation of NiAl2O4 was started between 15 to 20 hours of milling and completed after 60 hours. The final particle size was found to be in the range of 5-50 nm. (author)

  18. 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.

  19. Phase equilibria among {alpha}-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe{sub 3}Al-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Satoru [Department of Microstructure Physics and Metal Forming, Max Planck Institute fuer Eisenfoschung, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany) and Department of Materials Technology, Max Planck Institute fuer Eisenfoschung, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany)]. E-mail: kobayashi@mpie.de; Schneider, Andre [Department of Materials Technology, Max Planck Institute fuer Eisenfoschung, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany); Zaefferer, Stefan [Department of Microstructure Physics and Metal Forming, Max Planck Institute fuer Eisenfoschung, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany); Frommeyer, Georg [Department of Materials Technology, Max Planck Institute fuer Eisenfoschung, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany); Raabe, Dierk [Department of Microstructure Physics and Metal Forming, Max Planck Institute fuer Eisenfoschung, Max-Planck-Str. 1, D-40237 Duesseldorf (Germany)

    2005-08-15

    In the context of the development of high-strength Fe{sub 3}Al-based alloys, phase equilibria among {alpha}-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L <=> {alpha} + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr ({alpha}) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary {alpha} phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary {alpha}. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt.

  20. Thickness-controllable electrospun fibers promote tubular structure formation by endothelial progenitor cells

    Directory of Open Access Journals (Sweden)

    Hong JK

    2015-02-01

    Full Text Available Jong Kyu Hong,1,2 Ju Yup Bang,3 Guan Xu,4 Jun-Hee Lee,1 Yeon-Ju Kim,1 Ho-Jun Lee,5 Han Seong Kim,3 Sang-Mo Kwon1,2,6 1Laboratory for Vascular Medicine and Stem Cell Biology, Medical Research Institute, Department of Physiology, School of Medicine, Pusan National University, Yangsan, South Korea; 2Conversence Stem Cell Research Center, Medical Research Institute, School of Medicine, Pusan National University, Yangsan, South Korea; 3Department of Organic Material Science, Pusan National University, Geumjeong-gu, Busan, South Korea; 4Department of Radiology, School of Medicine, University of Michigan, Ann Arbor, MI, USA; 5Department of Electrical Engineering, Pusan National University, Geumjeong-gu, Busan, South Korea; 6Immunoregulatory Therapeutics Group in Brain Busan 21 Project, Department of Physiology, Pusan National University School of Medicine, Yangsan, South Korea Abstract: Controlling the thickness of an electrospun nanofibrous scaffold by altering its pore size has been shown to regulate cell behaviors such as cell infiltration into a three-dimensional (3D scaffold. This is of great importance when manufacturing tissue-engineering scaffolds using an electrospinning process. In this study, we report the development of a novel process whereby additional aluminum foil layers were applied to the accumulated electrospun fibers of an existing aluminum foil collector, effectively reducing the incidence of charge buildup. Using this process, we fabricated an electrospun scaffold with a large pore (pore size >40 µm while simultaneously controlling the thickness. We demonstrate that the large pore size triggered rapid infiltration (160 µm in 4 hours of cell culture of individual endothelial progenitor cells (EPCs and rapid cell colonization after seeding EPC spheroids. We confirmed that the 3D, but not two-dimensional, scaffold structures regulated tubular structure formation by the EPCs. Thus, incorporation of stem cells into a highly

  1. Co/Mg/Al hydrotalcite-type precursor, promoted with La and Ce, studied by XPS and applied to methane steam reforming reactions

    International Nuclear Information System (INIS)

    Catalysts' precursor of Co/Mg/Al promoted with Ce and La were tested in the steam reforming of methane (SRM). The addition of promoters was made by anion-exchange. The oxides characterization was made by X-ray Photoelectron Spectroscopy (XPS) analysis that confirmed Co2+ species in free form on surface and interacted with Mg and Al in the form of solid solution. In the SRM with high fed molar ratio of H2O:CH4 = 4:1, the catalysts showed a great affinity with water and immediately deactivated by oxidation of the active sites. In the stoichiometric ratio of H2O:CH4 = 2:1 the catalysts were active and presented low carbon deposition during the time reaction tested. Also a test with low fed molar ratio H2O:CH4 = 0.5:1 was carried out to evaluate the stability of the catalysts by CH4 decomposition and all the catalysts were stable during 6 h of reaction. Promoted catalysts presented lower carbon deposition

  2. Sulfur tolerance of Fe promoted BaO/Al2O3 systems as NOx storage materials

    OpenAIRE

    Parmak, Emrah

    2011-01-01

    Ternary mixed oxide systems in the form of BaO/FeOx/Al2O3 were studied with varying compositions as an alternative to the conventional NOx storage materials (i.e. BaO/Al2O3). NOx uptake properties of the freshly prepared samples, sulfur adsorption and NOx storage in the presence of sulfur were investigated in order to elucidate the sulfur tolerance of these advanced NOx storage systems in comparison to their conventional counterparts. The structural characterization of the p...

  3. 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)

  4. 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

  5. The Listeria monocytogenes hibernation-promoting factor is required for the formation of 100S ribosomes, optimal fitness, and pathogenesis.

    Science.gov (United States)

    Kline, Benjamin C; McKay, Susannah L; Tang, William W; Portnoy, Daniel A

    2015-02-01

    During exposure to certain stresses, bacteria dimerize pairs of 70S ribosomes into translationally silent 100S particles in a process called ribosome hibernation. Although the biological roles of ribosome hibernation are not completely understood, this process appears to represent a conserved and adaptive response that contributes to optimal survival during stress and post-exponential-phase growth. Hibernating ribosomes are formed by the activity of one or more highly conserved proteins; gammaproteobacteria produce two relevant proteins, ribosome modulation factor (RMF) and hibernation promoting factor (HPF), while most Gram-positive bacteria produce a single, longer HPF protein. Here, we report the formation of 100S ribosomes by an HPF homolog in Listeria monocytogenes. L. monocytogenes 100S ribosomes were observed by sucrose density gradient centrifugation of bacterial extracts during mid-logarithmic phase, peaked at the transition to stationary phase, and persisted at lower levels during post-exponential-phase growth. 100S ribosomes were undetectable in bacteria carrying an hpf::Himar1 transposon insertion, indicating that HPF is required for ribosome hibernation in L. monocytogenes. Additionally, epitope-tagged HPF cosedimented with 100S ribosomes, supporting its previously described direct role in 100S formation. We examined hpf mRNA by quantitative PCR (qPCR) and identified several conditions that upregulated its expression, including carbon starvation, heat shock, and exposure to high concentrations of salt or ethanol. Survival of HPF-deficient bacteria was impaired under certain conditions both in vitro and during animal infection, providing evidence for the biological relevance of 100S ribosome formation. PMID:25422304

  6. 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

  7. 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.

  8. 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.

  9. 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)

  10. 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 phase...... transition clearly follows an allometric dependence on tau(Q) with a scaling exponent sigma=0.5, as predicted from the Zurek-Kibble mechanism for realistic JTJs formed by strongly coupled superconductors. This definitive experiment replaces one reported by us earlier, in which an idealized model was used...

  11. The research of Ti-rich zone on the interface between TiCx and aluminum melt and the formation of Ti3Al in rapid solidified Al-Ti-C master alloys

    International Nuclear Information System (INIS)

    In the present work, the thermodynamic tendency of formation of Ti-rich zone on the interface between TiCx and aluminum melt is calculated and a high titanium concentration can exist in the zone according to the thermodynamic calculation. Rapid solidified Al-5Ti-0.5C master alloy is analyzed by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). The appearance of Ti3Al in the master alloy results from the existence of high-concentration Ti-rich zone.

  12. 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.

  13. The Promotion of Antibacterial Effects of Ti6Al4V Alloy Modified with TiO2 Nanotubes Using a Superoxidized Solution

    Directory of Open Access Journals (Sweden)

    Ernesto Beltrán-Partida

    2015-01-01

    Full Text Available The purpose of the present study was to synthetize 80 nm diameter TiO2 nanotubes (NTs on Ti6Al4V alloy using a commercially superoxidized water (SOW enriched with fluoride to reduce anodization time and promote the antibacterial efficacy against Staphylococcus aureus (S. aureus. The alloy discs were anodized for 5 min and as a result, NTs of approximately 80 nm diameters were obtained with similar morphology as reported in previous studies using longer anodization times (1-2 h. Filed emission-scanning electron microscopy (FE-SEM and energy dispersive X-ray spectroscopy (EDX were used to characterize the materials surfaces. The NTs showed significantly decreased S. aureus viability after 1, 3, and 5 days of culture in comparison to nonanodized alloy. Likewise, SEM analysis also suggested lower bacterial adhesion on the NTs surface. No differences in bacterial morphology and topography were observed on both materials, as analyzed by SEM and atomic force microscopy (AFM. In conclusion, 80 nm diameter NTs were grown on Ti6Al4V alloy in 5 min by using a SOW solution enriched with fluoride, which resulted in a material with promoted antibacterial efficacy against S. aureus for up to 5 days of in vitro culture when compared to nonanodized alloy.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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).

  2. 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.

  3. 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.

  4. 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...

  5. 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.

  6. 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 ...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Effect of interlayer configurations on joint formation in TLP bonding of Ti-6Al-4V to Mg-AZ31

    International Nuclear Information System (INIS)

    In this research work, the transient liquid phase (TLP) bonding process was utilized to fabricate joints using thin (20μm) nickel and copper foils placed between two bonding surfaces to help facilitate joint formation. Two joint configurations were investigated, first, Ti-6Al-4V/CuNi/Mg-AZ31 and second, Ti-6Al-4V/NiCu/Mg-AZ3L The effect of bonding time on microstructural developments across the joint and the changes in mechanical properties were studied as a function of bonding temperature and pressure. The bonded specimens were examined by metallographic analysis, scanning electron microscopy (SEM), and X-ray diffraction (XRD). In both cases, intermetallic phase of CuMg2 and Mg3AlNi2 was observed inside the joint region. The results show that joint shear strengths for the Ti-6Al-4V/CuNi/Mg-AZ31 setup produce joints with shear strength of 57 MPa compared to 27MPa for joints made using the Ti-6Al-4V/NiCu/Mg-AZ31 layer arrangement

  15. Consideration of the formation mechanism of an Al2O3-HfO2 eutectic film on a SiC substrate

    Science.gov (United States)

    Seya, Kyosuke; Ueno, Shunkichi; Nishimura, Toshiyuki; Jang, Byung-Koog

    2016-01-01

    An Al2O3-HfO2 eutectic EBC film was prepared on a SiC substrate by using the electric furnace heating and the optical zone melting methods. All of Al2O3 phase disappeared during the heating step at a temperature below the melting point, and all of the HfO2 phase reacted with the carbon and boron, which are included in SiC bulk as sintering agents, during the heating step at a temperature below the melting point. The thermal decomposition of the SiC phase, the reduction reaction of Al2O3 phase, the vaporization of the Al2O3 component, the reduction reaction of HfO2 and the formation of the HfC phase occurred at a temperature below the melting point. However, a highly dense HfC phase was formed on the SiC substrate. A rapid heating process becomes possible by using the optical zone melting method. A solidified film that was composed of a highly dense HfC layer as the intermediate layer and the Al2O3-HfO2 eutectic structure layer as the top coat was obtained by using the optical zone melting method.

  16. Effect of human hepatocyte growth factor on promoting wound healing and preventing scar formation by adenovirus-mediated gene transfer

    Institute of Scientific and Technical Information of China (English)

    哈小琴; 李元敏; 劳妙芬; 苑宾; 吴祖泽

    2003-01-01

    Objective To evaluate the effects of hepatocyte growth factor (HGF) on the prevention of scar formation and the promotion of wound healing by gene transfer. Methods A total of 12 female New Zealand rabbits were used in this study. Rabbits were anesthetized with an intravenous injection of sodium pentobarbital, and identical wounds were made over the ventral surface of each ear. Five circular wounds, 7 mm in diameter, were created in each ear by excision through the skin to the underlying cartilage using sterile technique. After the surgical procedures, 10 of the rabbits were randomly allocated to five groups, with 2 rabbits in each group: Ad-HGF group 1, Ad-HGF group 2, Ad-HGF group 3, Ad-GFP (a reporter gene) group and the solvent group. Immediately after surgery, 6×107 pfu Ad-HGF, 6×108 pfu Ad-HGF, 6×109 pfu of Ad-HGF, 6×109 pfu of Ad-GFP, or same volume of solvent (PBS, pH 7.2) was applied once to each wound in groups 1 to 5, respectively. One additional rabbit was used to evaluate the transfer efficiency of the adenovirus vector by transferring Ad-GFP (6×109 pfu) into its wounds. Ice slides of wounds from this animal were observed under fluorescence microscopy. Another additional rabbit was used to evaluate the expression of HGF and TGFβ1 after transferring Ad-HGF (6×109 pfu) into each of its wound. Immunohistochemistry was used for detection. Results The effect of HGF on reducing excessive dermal scarring was observed by adenovirus-mediated gene transfer. Transfection of the human HGF cDNA into skin wounds through an adenoviral vector suppressed the over-expression of TGFβ1, which plays an essential role in the progression of dermal fibrogenesis. Application of HGF to the wounds significantly enhanced wound healing and inhibited over scarring.Conclusion HGF gene therapy could be a new approach for preventing excessive dermal scarring in wound healing.

  17. Promotion of peripheral nerve regeneration and prevention of neuroma formation by PRGD/PDLLA/β-TCP conduit: report of two cases

    OpenAIRE

    Yin, Yixia; Li, Binbin; Yan, Qiongjiao; Dai, Honglian; Wang, Xinyu; Huang, Jifeng; Li, Shipu

    2015-01-01

    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...

  18. 助剂Ni与载体的相互作用及其对NiMo/γ-Al2 O3催化剂加氢脱硫性能的影响%Interaction between Ni promoter and Al2 O3 support and its effect on the performance of NiMo/γ-Al2O3 catalyst in hydrodesulphurization

    Institute of Scientific and Technical Information of China (English)

    赵瑞玉; 曹东炜; 曾令有; 梁娟; 刘晨光

    2016-01-01

    以γ-Al2 O3为载体,制备了一系列不同NiO负载量的NiMo/γ-Al2 O3催化剂,利用XRD、27 Al-MAS NMR、Py-FTIR和HRTEM等技术对其进行了表征;在高压微反装置对该系列催化剂的加氢脱硫性能进行了评价,研究了助剂 Ni 与载体γ-Al2 O3中不饱和铝间的相互作用及其对催化剂活性相结构形貌和催化活性的影响。结果表明,助剂Ni优先作用于γ-Al2 O3表面的四配位不饱和铝原子位置;随着NiO负载量的增加,硫化态NiMo/γ-Al2 O3催化剂中MoS2活性相的长度变短、堆垛层数增加。 Ni的引入能明显提高NiMo/γ-Al2 O3催化剂的加氢脱硫活性,但其加氢选择性则有所降低。%A series of NiMo/γ-Al2 O3 catalysts with different NiO loadings were prepared and characterized by XRD, BET, 27 Al-NMR, Py-IR and HRTEM. The activity of these NiMo/γ-Al2 O3 catalysts in the hydrodesulphurization ( HDS) of dibenzothiophene ( DBT) was evaluated in a high pressure micro reactor; the interaction between Ni promoter and γ-Al2 O3 support as well as its effect on the nanostructure of active MoS2 phase and HDS performance was then investigated. The results indicate that Ni promoter prefers to interact with the tetra-coordinated unsaturated aluminum sites on the support surface. With the increase of NiO loading, the average number of stacking layers for the MoS2 clusters in the sulfided NiMo/γ-Al2 O3 catalysts is increased at the expense of the average length. As the slim MoS2 clusters are more active for the HDS of DBT, the addition of Ni promoter is then effective to enhance the catalytic activity of NiMo/γ-Al2 O3 in HDS, but may lead to a slight decrease in the hydrogenation selectivity.

  19. Effects of struvite formation and nitratation promotion on nitrogenous emissions such as NH3, N2O and NO during swine manure composting.

    Science.gov (United States)

    Fukumoto, Yasuyuki; Suzuki, Kazuyoshi; Kuroda, Kazutaka; Waki, Miyoko; Yasuda, Tomoko

    2011-01-01

    To reduce nitrogenous emissions from composting, two different countermeasures were applied simultaneously in swine manure composting. One was forming struvite by adding Mg and P at the start of composting, and the other was to promote nitratation (nitrite being oxidized nitrate) by adding nitrite-oxidizing bacteria after the thermophilic phase of composting. In the laboratory- and mid-scale composting experiments, 25-43% of NH3, 52-80% of N2O and 96-99% of NO emissions were reduced. From the nitrogen balance, it was revealed that the struvite formation reduced not only NH3, but also other nitrogenous emissions except N2O. The amount of total nitrogen losses was reduced by 60% by the two combined countermeasures, against 51% by the struvite formation alone. However, the nitratation promotion dissolved struvite crystals due to the pH decline, diminishing the effect of struvite as a slow-release fertilizer. PMID:20952186

  20. 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...

  1. Constraints on silicates formation in the Si-Al-Fe system: Application to hard deposits in steam generators of PWR nuclear reactors

    Science.gov (United States)

    Berger, Gilles; Million-Picallion, Lisa; Lefevre, Grégory; Delaunay, Sophie

    2015-04-01

    Introduction: The hydrothermal crystallization of silicates phases in the Si-Al-Fe system may lead to industrial constraints that can be encountered in the nuclear industry in at least two contexts: the geological repository for nuclear wastes and the formation of hard sludges in the steam generator of the PWR nuclear plants. In the first situation, the chemical reactions between the Fe-canister and the surrounding clays have been extensively studied in laboratory [1-7] and pilot experiments [8]. These studies demonstrated that the high reactivity of metallic iron leads to the formation of Fe-silicates, berthierine like, in a wide range of temperature. By contrast, the formation of deposits in the steam generators of PWR plants, called hard sludges, is a newer and less studied issue which can affect the reactor performance. Experiments: We present here a preliminary set of experiments reproducing the formation of hard sludges under conditions representative of the steam generator of PWR power plant: 275°C, diluted solutions maintained at low potential by hydrazine addition and at alkaline pH by low concentrations of amines and ammoniac. Magnetite, a corrosion by-product of the secondary circuit, is the source of iron while aqueous Si and Al, the major impurities in this system, are supplied either as trace elements in the circulating solution or by addition of amorphous silica and alumina when considering confined zones. The fluid chemistry is monitored by sampling aliquots of the solution. Eh and pH are continuously measured by hydrothermal Cormet© electrodes implanted in a titanium hydrothermal reactor. The transformation, or not, of the solid fraction was examined post-mortem. These experiments evidenced the role of Al colloids as precursor of cements composed of kaolinite and boehmite, and the passivation of amorphous silica (becoming unreactive) likely by sorption of aqueous iron. But no Fe-bearing was formed by contrast to many published studies on the Fe

  2. 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

  3. 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.

  4. The formation of double-row oxide stripes during the initial oxidation of NiAl(100)

    Science.gov (United States)

    Qin, Hailang; Zhou, Guangwen

    2013-08-01

    The initial growth of ultrathin aluminum oxide film during the oxidation of NiAl(100) was studied with scanning tunneling microscopy. Our observations reveal that the oxide film grows initially as pairs of a double-row stripe structure with a lateral size equal to the unit cell of θ-Al2O3. These double-row stripes serve as the very basic stable building units of the ordered oxide phase for growing thicker bulk-oxide-like thin films. It is shown that the electronic properties of these ultrathin double-row stripes do not differ significantly from that of the clean NiAl surface; however, the thicker oxide stripes show a decreased conductivity.

  5. The formation of double-row oxide stripes during the initial oxidation of NiAl(100)

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Hailang; Zhou, Guangwen [Department of Mechanical Engineering and Multidisciplinary Program in Materials Science and Engineering, State University of New York, Binghamton, New York 13902 (United States)

    2013-08-28

    The initial growth of ultrathin aluminum oxide film during the oxidation of NiAl(100) was studied with scanning tunneling microscopy. Our observations reveal that the oxide film grows initially as pairs of a double-row stripe structure with a lateral size equal to the unit cell of θ-Al{sub 2}O{sub 3}. These double-row stripes serve as the very basic stable building units of the ordered oxide phase for growing thicker bulk-oxide-like thin films. It is shown that the electronic properties of these ultrathin double-row stripes do not differ significantly from that of the clean NiAl surface; however, the thicker oxide stripes show a decreased conductivity.

  6. The formation of double-row oxide stripes during the initial oxidation of NiAl(100)

    International Nuclear Information System (INIS)

    The initial growth of ultrathin aluminum oxide film during the oxidation of NiAl(100) was studied with scanning tunneling microscopy. Our observations reveal that the oxide film grows initially as pairs of a double-row stripe structure with a lateral size equal to the unit cell of θ-Al2O3. These double-row stripes serve as the very basic stable building units of the ordered oxide phase for growing thicker bulk-oxide-like thin films. It is shown that the electronic properties of these ultrathin double-row stripes do not differ significantly from that of the clean NiAl surface; however, the thicker oxide stripes show a decreased conductivity

  7. All-trans retinoic acid impairs the vasculogenic mimicry formation ability of U87 stem-like cells through promoting differentiation

    OpenAIRE

    LING, GENG-QIANG; LIU, YI-JING; Ke, Yi-Quan; Chen, Lei; JIANG, XIAO-DAN; JIANG, CHUAN-LU; Ye, Wei

    2015-01-01

    The poor therapeutic effect of traditional antiangiogenic therapy on glioblastoma multiforme (GBM) may be attributed to vasculogenic mimicry (VM), which was previously reported to be promoted by cancer stem-like cells (SLCs). All-trans retinoic acid (ATRA), a potent reagent which drives differentiation, was reported to be able to eradicate cancer SLCs in certain malignancies. The aim of the present study was to investigate the effects of ATRA on the VM formation ability of U87 glioblastoma SL...

  8. Influence of temperature and rooting-promoter on the formation of root-primodia and on the rooting of chrysanthemum cuttings under storage

    International Nuclear Information System (INIS)

    In order to promote rooting for direct planting cuttings in a lighting cultivation of chrysanthemum, we clarified the effects of light, temperature and term of storage of the cuttings, and analyzed ways of using rooting promoters as a pre-treatment of cuttings for root-primodia formation and rooting. Light as a pre-treatment had little effect, so it seemed to be not necessary for the formation of root primodia. The formation of the root-primodia was most hastened at 25 degrees C; inversely, it was slowed down at low temperatures, that is, the root-primodia were formed in four days at 25 degrees C, five days at 20 degrees C, and seven days at 15 degrees C. With the use of rooting promoters as a pre-treatment for the rooting of cuttings, the root-primodia were formed faster when the whole of cuttings were dipped in 40 mg/L solution of indelebutyric acid (IBA) than when the base of cuttings were dipped or sprayed 400 mg/L solution of IBA. It was appropriate that cuttings were dipped in IBA then put in in plastic-pots (7.5cm) vertically, packed in polyethylene-bags and stored in a corrugated carton box

  9. AlSi12 In-Situ Alloy Formation and Residual Stress Reduction using Anchorless Selective Laser Melting

    OpenAIRE

    Mumtaz, K.A.; I. Todd; Hopkinson, N; Vora, P.

    2015-01-01

    Rapid melt pool formation and solidification during the metal powder bed process Selective Laser Melting (SLM) generates large thermal gradients that can in turn lead to increased residual stress formation within a component. Metal anchors or supports are required to be built in-situ and forcibly hold SLM structures in place and minimise geometric distortion/warpage as a result of this thermal residual stress. Anchors are often costly, difficult and time consuming to remove and limit the geom...

  10. Localization of shear strain and shear band formation induced by deformation in semi-solid Al-Cu alloys

    Science.gov (United States)

    Nagira, T.; Morita, S.; Yasuda, H.; Gourlay, C. M.; Yoshiya, M.; Sugiyama, A.; Uesugi, K.

    2015-06-01

    In situ observation of deformation in globular Al-Cu samples at a solid fraction of ∼⃒50% and a global shear strain rate of 10-1 s-1 was performed using time-resolved X-ray imaging. The solid particle motion during shear was quantitatively analysed. The force was transmitted though the contacts between solid particles over a long distance parallel to the shear plane (18 mean grain size, d) after only a 1d increment of the Al2O3 push-plate motion. On the other hand, the distance of transmitted force in the perpendicular direction to the shear plane was restricted to approximately 11d even for a high displacement of the Al2O3 push-plate. A relatively high shear strain rate became localized at the shear domain after a small amount of deformation (a 1d increment). The solid fraction decreased in the region of localized shear strain rate. The shear band width, where the shear strain was localized and the solid fraction decreased, remained mostly unchanged over a 4 d increment of Al2O3 push-plate motion.

  11. 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

  12. 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.

  13. Size ratio induced yttrium aluminum garnet formation characteristics in nano-scaled Y2O3-Al2O3 powder systems via fast firing processes

    International Nuclear Information System (INIS)

    Highlights: → This study examined YAG synthesis using Y2O3 and Al2O3 as the starting materials. → Appropriate size ratios of oxides and fast firing treatments favored YAG synthesis. → Interface- and diffusion-controlled mechanism can be occurred during YAG formation. → Finer Y2O3 particles can react to pure YAG rapidly by interface-controlled mechanism. → In coarser Y2O3 particles, pure YAG attained by two reaction mechanisms in turn. - Abstract: The formation characteristics of YAG phase synthesized by fast-firing Y2O3 and Al2O3 powder mixtures were examined. Y2O3 powders of 100, 350, and 500 nm in D50 were mixed with α-Al2O3 powder of (D50) 200 nm to obtain starting powders denoted as S0.5, S1.75, and S2.5, respectively. In these mixtures, the two oxides contacted wholly with each other but varied in number of contact points and diffusion length. This study aimed to eliminate the YAM and YAP phases, which normally occur during YAG formation. Examinations were conducted using pressed compacts (bulk density of 0.91 g cm-3) prepared with the three mixtures. After pre-heating at 700 deg. C for 30 s, the compacts were plunged at temperatures of 1050-1450 deg. C for 5-60 s and then quenched to room temperature. In the S0.5 system, one-step YAG formation occurred by an interface-controlled mechanism, and intermediates were apparently suppressed. However, YAG formation was divided into two stages in the S1.75 and S2.5 systems. Two stages were defined by the heating duration prior to and after 20 s. The interface-controlled mechanism was dominant in the initial stage, and then the diffusion-controlled mechanism was dominant in the second stage, in which YAG formed sluggishly and substantial amounts of YAM and YAP persisted. However, both stages followed the conversion sequence of YAM to YAP and then to YAG. Accordingly, two YAG formation routes derived from reacted Y2O3 of different sizes are proposed. Finally, a pure YAG phase could be obtained by calcining

  14. 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.).

  15. Microstructural evolution and intermetallic formation in Al-8wt% Si-0.8wt% Fe alloy due to grain refiner and modifier additions

    Science.gov (United States)

    Hassani, Amir; Ranjbar, Khalil; Sami, Sattar

    2012-08-01

    An alloy of Al-8wt% Si-0.8wt% Fe was cast in a metallic die, and its microstructural changes due to Ti-B refiner and Sr modifier additions were studied. Apart from usual refinement and modification of the microstructure, some mutual influences of the additives took place, and no mutual poisoning effects by these additives, in combined form, were observed. It was noticed that the dimensions of the iron-rich intermetallics were influenced by the additives causing them to become larger. The needle-shaped intermetallics that were obtained from refiner addition became thicker and longer when adding the modifier. It was also found that α-Al and eutectic silicon phases preferentially nucleate on different types of intermetallic compounds. The more iron content of the intermetallic compounds and the more changes in their dimensions occurred. Formation of the shrinkage porosities was also observed.

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

    OpenAIRE

    Xiaogang Jian; Qingyou Han

    2013-01-01

    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 o...

  17. 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.

  18. Constraints on the Formation of the Galactic Bulge from Na, Al, and Heavy Element Abundances in Plaut's Field

    CERN Document Server

    Johnson, Christian I; Kobayashi, Chiaki; Fulbright, Jon P

    2012-01-01

    We report chemical abundances of Na, Al, Zr, La, Nd, and Eu for 39 red giant branch (RGB) stars and 23 potential inner disk red clump stars located in Plaut-s low extinction window. We also measure lithium for a super Li-rich RGB star. The abundances were determined by spectrum synthesis of high resolution (R~25,000), high signal-to-noise (S/N~50-100 pixel-1) spectra obtained with the Blanco 4m telescope and Hydra multifiber spectrograph. For the bulge RGB stars, we find a general increase in the [Na/Fe] and [Na/Al] ratios with increasing metallicity, and a similar decrease in [La/Fe] and [Nd/Fe]. Additionally, the [Al/Fe] and [Eu/Fe] abundance trends almost identically follow those of the {\\alpha}-elements, and the [Zr/Fe] ratios exhibit relatively little change with [Fe/H]. The consistently low [La/Eu] ratios of the RGB stars indicate that at least a majority of bulge stars formed rapidly (<1 Gyr) and before the main s-process could become a significant pollution source. In contrast, we find that the pot...

  19. 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.

  20. 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.

    2016-08-01

    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.

  1. 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.

  2. Triple helix formation with the promoter of human alpha1(I) procollagen gene by an antiparallel triplex-forming oligodeoxyribonucleotide.

    OpenAIRE

    Nakanishi, M.; K. T. Weber; Guntaka, R V

    1998-01-01

    The promoters of alpha1(I) procollagen genes of vertebrates contain two contiguous stretches of polypyrimidine/polypurine sequences, referred to as C1 (-140 to -170) and C2 (-171 to -200). Antiparallel triplex-forming upstream oligonucleotides form efficient triplexes with C1. The C1 tract of human differs from rodent alpha1(I) promoters by 7 nt which are mainly A-->G transitions. Human triplex-forming oligodeoxyribonucleotide (TFO) formed stable triplexes efficiently with a K d of approximat...

  3. Do formative assessments promote self assessment accuracy? A study of second year medical students’ predictions about performance

    OpenAIRE

    Relan, Anju; Guiton, Gretchen; Sopher, Michael; Goldhaber, Josh

    2006-01-01

    Self assessment accuracy is an essential precursor to the development of self-directed learning- a desired goal of medical education. The purpose of this study was to determine medical students’ long term accuracy of performance prediction, evaluated in the context of formative assessments designed to provide practice for the summative assessment. Students were asked to predict their performance on the final exam over six formative assessments and at the end of the final exam. Students’ co...

  4. Endothelial Progenitor Cells Promote Directional Three-Dimensional Endothelial Network Formation by Secreting Vascular Endothelial Growth Factor

    OpenAIRE

    Yoshinori Abe; Yoshiyuki Ozaki; Junichi Kasuya; Kimiko Yamamoto; Joji Ando; Ryo Sudo; Mariko Ikeda; Kazuo Tanishita

    2013-01-01

    Endothelial progenitor cell (EPC) transplantation induces the formation of new blood-vessel networks to supply nutrients and oxygen, and is feasible for the treatment of ischemia and cardiovascular diseases. However, the role of EPCs as a source of proangiogenic cytokines and consequent generators of an extracellular growth factor microenvironment in three-dimensional (3D) microvessel formation is not fully understood. We focused on the contribution of EPCs as a source of proangiogenic cytoki...

  5. 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.

  6. Methanation of carbon dioxide on Ni/ZrO2-Al2O3 catalysts: Effects of ZrO2 promoter and preparation method of novel ZrO2-Al2O3 carrier

    Institute of Scientific and Technical Information of China (English)

    Mengdie Cai; Jie Wen; Wei Chu; Xueqing Cheng; Zejun Li

    2011-01-01

    The novel nickel-based catalysts with a nickel content of 12 wt% were prepared with the zirconia-alumina composite as the supports. The new carriers, ZrO2 improved alumina, were synthesized by three methods, i.e., impregnation-precipitation, co-precipitation, and impregnation method. The catalytic properties of these catalysts were investigated in the methanation of carbon dioxide, and the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS), temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) techniques. The new catalysts showed higher catalytic activity and better stability than Ni/γ-AI2O3. Furthermore, as a support for new nickel catalyst, the ZrO2-AI2O3 composite prepared by the impregnation-precipitation method was more efficient than the other supports in the methanation of carbon dioxide. The highly dispersed zirconium oxide on the surface of γ-Al2O3 inhibited the formation of nickel aluminate-like phase, which was responsible for the better dispersion of Ni species and easier reduction of NiO species, leading to the enhanced catalytic performance of corresponding catalyst.

  7. 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

  8. 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 ...

  9. XANES and Mg isotopic analyses of spinels in Ca-Al-rich inclusions: Evidence for formation under oxidizing conditions

    OpenAIRE

    Paque, J. M.; Sutton, S. R.; Simon, S. B.; Beckett, J. R.; Burnett, D. S.; Grossman, L; Yurimoto, H.; Itoh, S; Connolly, H. C.

    2013-01-01

    Ti valence measurements in MgAl_2O_4 spinel from calcium-aluminum-rich inclusions (CAIs) by X-ray absorption near-edge structure (XANES) spectroscopy show that many spinels have predominantly tetravalent Ti, regardless of host phases. The average spinel in Allende type B1 inclusion TS34 has 87% Ti^(+4). Most spinels in fluffy type A (FTA) inclusions also have high Ti valence. In contrast, the rims of some spinels in TS34 and spinel grain cores in two Vigarano type B inclusions have larger amo...

  10. The BR domain of PsrP interacts with extracellular DNA to promote bacterial aggregation; structural insights into pneumococcal biofilm formation

    Science.gov (United States)

    Schulte, Tim; Mikaelsson, Cecilia; Beaussart, Audrey; Kikhney, Alexey; Deshmukh, Maya; Wolniak, Sebastian; Pathak, Anuj; Ebel, Christine; Löfling, Jonas; Fogolari, Federico; Henriques-Normark, Birgitta; Dufrêne, Yves F.; Svergun, Dmitri; Nygren, Per-Åke; Achour, Adnane

    2016-01-01

    The major human pathogen Streptococcus pneumoniae is a leading cause of disease and death worldwide. Pneumococcal biofilm formation within the nasopharynx leads to long-term colonization and persistence within the host. We have previously demonstrated that the capsular surface-associated pneumococcal serine rich repeat protein (PsrP), key factor for biofilm formation, binds to keratin-10 (KRT10) through its microbial surface component recognizing adhesive matrix molecule (MSCRAMM)-related globular binding region domain (BR187–385). Here, we show that BR187–385 also binds to DNA, as demonstrated by electrophoretic mobility shift assays and size exclusion chromatography. Further, heterologous expression of BR187–378 or the longer BR120–378 construct on the surface of a Gram-positive model host bacterium resulted in the formation of cellular aggregates that was significantly enhanced in the presence of DNA. Crystal structure analyses revealed the formation of BR187–385 homo-dimers via an intermolecular β-sheet, resulting in a positively charged concave surface, shaped to accommodate the acidic helical DNA structure. Furthermore, small angle X-ray scattering and circular dichroism studies indicate that the aggregate-enhancing N-terminal region of BR120–166 adopts an extended, non-globular structure. Altogether, our results suggest that PsrP adheres to extracellular DNA in the biofilm matrix and thus promotes pneumococcal biofilm formation. PMID:27582320

  11. 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.

  12. 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.

  13. Influence of cooling rate and addition of lanthanum and cerium on formation of nanoporous copper by chemical dealloying of Cu15Al85 alloy

    Institute of Scientific and Technical Information of China (English)

    姜华伟; 李捷; 耿浩然; 王庆磊

    2013-01-01

    The influence of cooling rate and addition of La and Ce on the formation of nanoporous copper by chemical dealloying of Cu15Al85 alloy was studied. The components and microstructures of nanoporous copper were characterized by utilizing X-ray diffrac-tion, field emission scanning electron microscopy and energy dispersive X-ray analysis. N2 adsorption/desorption experiments were used to evaluate specific surface areas of samples. The results showed that, with the increase of cooling rate, phase composition of precursor alloy almost had no change, the ligament size of nanoporous copper had a decrease trend, and specific surface area in-creased gradually. And it was found that the specific surface area of the nanoporous copper obtained by Cu15Al85 alloy containing La and Ce was 63.258 m2/g, which was more than 11.739 m2/g compared with the nanoporous copper dealloying by Cu15Al85 alloy without La and Ce under the same conditions.

  14. Effect of slag composition on the kinetics of formation of Al{sub 2}O{sub 3}-MgO inclusions in aluminium killed ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, G.

    2000-02-01

    Kinetics of both slag/metal reactions and metal/inclusion reactions were investigated experimentally using 20kg vacuum induction furnace in order to clarify the mechanism of the formation of MgAl{sub 2}O{sub 4} spinel inclusions in aluminum killed ferritic stainless steel (SUS430). The results obtained are summarized as follows: (1) By reducing CaO/SiO{sub 2} and CaO/Al{sub 2}O{sub 3} ratio of top slag, MgO contents in Al{sub 2}O{sub 3} based inclusions decreased. (2) The two film theory was employed to analyze the rate determining step of slag/metal reaction (reduction of MgO in top slag). By this model, it was found that the rate determining step of the reaction was the mass transfer of Mg through the film in molten steel. The increase rate of Mg in molten steel is determined by the activities of soluble oxygen and MgO at the slag/metal interface, and hence by slag composition. (3) The unreacted core model was employed to analyze the rate determining step of metal/inclusions reaction. The analysis showed that the rate determining step of the reaction in the case of 20 kg vacuum induction furnace was the diffusion of Mg in molten steel. (author)

  15. Retention of wild-type p53 in tumors from p53 heterozygous mice: reduction of p53 dosage can promote cancer formation.

    OpenAIRE

    Venkatachalam, S; Shi, Y P; Jones, S N; Vogel, H.; Bradley, A.; Pinkel, D; Donehower, L A

    1998-01-01

    Tumor suppressor genes are generally viewed as being recessive at the cellular level, so that mutation or loss of both tumor suppressor alleles is a prerequisite for tumor formation. The tumor suppressor gene, p53, is mutated in approximately 50% of human sporadic cancers and in an inherited cancer predisposition (Li-Fraumeni syndrome). We have analyzed the status of the wild-type p53 allele in tumors taken from p53-deficient heterozygous (p53+/-) mice. These mice inherit a single null p53 al...

  16. Influence of UFG structure formation on mechanical and fatigue properties in Ti-6Al-7Nb alloy

    Science.gov (United States)

    Polyakova, V. V.; Anumalasetty, V. N.; Semenova, I. P.; Valiev, R. Z.

    2014-08-01

    Ultrafine-grained (UFG) Ti alloys have potential applications in osteosynthesis and orthopedics due to high bio-compatibility and increased weight-to- strength ratio. In current study, Ti6Al7Nb ELI alloy is processed through equal channel angular pressing-conform (ECAP-Conform) and subsequent thermomechanical processing to generate a UFG microstructure. The fatigue properties of UFG alloys are compared to coarse grained (CG) alloys. Our study demonstrates that the UFG alloys with an average grain size of ~180 nm showed 35% enhancement of fatigue endurance limit as compared to coarse-grained alloys. On the fracture surfaces of the UFG and CG samples fatigue striations and dimpled relief were observed. However, the fracture surface of the UFG sample looks smoother; fewer amounts of secondary micro-cracks and more ductile rupture were also observed, which testifies to the good crack resistance in the UFG alloy after high-cyclic fatigue tests.

  17. Effect of valence holes on swift heavy ion track formation in Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Terekhin, P.N., E-mail: p.n.terekhin@yandex.ru [National Research Centre ‘Kurchatov Institute’, Kurchatov Sq. 1, 123182 Moscow (Russian Federation); Rymzhanov, R.A. [JINR, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Gorbunov, S.A. [LPI of the Russian Academy of Sciences, Leninskij pr., 53, 119991 Moscow (Russian Federation); Medvedev, N.A. [Center for Free-Electron Laser Science at DESY, Notkestr. 85, 22607 Hamburg (Germany); Volkov, A.E. [National Research Centre ‘Kurchatov Institute’, Kurchatov Sq. 1, 123182 Moscow (Russian Federation); JINR, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); LPI of the Russian Academy of Sciences, Leninskij pr., 53, 119991 Moscow (Russian Federation)

    2015-07-01

    This paper focuses on effects of electrons and valence holes on structure modifications in swift heavy ion (SHI) tracks in dielectrics. To investigate this problem a multiscale model is constructed which consists of (a) Monte Carlo modeling of a SHI penetration and secondary electron cascading; (b) molecular-kinetic approach for low-energy electrons spatial redistribution after finishing of ionization cascades; (c) molecular dynamics modeling of lattice excitation due to its coupling with the relaxing electron ensemble and subsequent atomic dynamics on picoseconds timescales. The model is applied to 167 MeV Xe ion irradiation of solid Al{sub 2}O{sub 3}. We found that lattice heating by excited electrons does not exceed ∼200 K, which is not sufficient to form an ion track observed in experiments. Structure transformations appear in the numerical simulations only when the excess energy accumulated in valence holes is taken into account.

  18. 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. PMID:27142875

  19. 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

    2016-05-01

    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.

  20. 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.

  1. Chemical modification of triplex-forming oligonucleotide to promote pyrimidine motif triplex formation at physiological pH.

    Science.gov (United States)

    Torigoe, Hidetaka; Nakagawa, Osamu; Imanishi, Takeshi; Obika, Satoshi; Sasaki, Kiyomi

    2012-04-01

    Extreme instability of pyrimidine motif triplex DNA at physiological pH severely limits its use in wide variety of potential applications, such as artificial regulation of gene expression, mapping of genomic DNA, and gene-targeted mutagenesis in vivo. Stabilization of pyrimidine motif triplex at physiological pH is, therefore, crucial for improving its potential in various triplex-formation-based strategies in vivo. To this end, we investigated the effect of 3'-amino-2'-O,4'-C-methylene bridged nucleic acid modification of triplex-forming oligonucleotide (TFO), in which 2'-O and 4'-C of the sugar moiety were bridged with the methylene chain and 3'-O was replaced by 3'-NH, on pyrimidine motif triplex formation at physiological pH. The modification not only significantly increased the thermal stability of the triplex but also increased the binding constant of triplex formation about 15-fold. The increased magnitude of the binding constant was not significantly changed when the number and position of the modification in TFO changed. The consideration of the observed thermodynamic parameters suggested that the increased rigidity of the modified TFO in the free state resulting from the bridging of different positions of the sugar moiety with an alkyl chain and the increased hydration of the modified TFO in the free state caused by the introduction of polar nitrogen atoms may significantly increase the binding constant at physiological pH. The study on the TFO viability in human serum showed that the modification significantly increased the resistance of TFO against nuclease degradation. This study presents an effective approach for designing novel chemically modified TFOs with higher binding affinity of triplex formation at physiological pH and higher nuclease resistance under physiological condition, which may eventually lead to progress in various triplex-formation-based strategies in vivo. PMID:22245184

  2. 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.

  3. BM-MSCs and Bio-Oss complexes enhanced new bone formation during maxillary sinus floor augmentation by promoting differentiation of BM-MSCs.

    Science.gov (United States)

    Zhou, Qian; Yu, Bo-Han; Liu, Wei-Cai; Wang, Zuo-Lin

    2016-08-01

    Bone marrow-derived mesenchymal stem cells (BM-MSCs) have been recognized as a new strategy for maxillary sinus floor elevation. However, little is known concerning the effect of the biomechanical pressure (i.e., sinus pressure, masticatory pressure, and respiration) on the differentiation of BM-MSCs and the formation of new bone during maxillary sinus floor elevation. The differentiation of BM-MSCs into osteoblasts was examined in vitro under cyclic compressive pressure using the Flexcell® pressure system, and by immunohistochemical analysis, qRT-PCR, and Western blot. Micro-CT was used to detect bone formation and allow image reconstruction of the entire maxillary sinus floor elevation area. Differentiation of BM-MSCs into osteoblasts was significantly increased under cyclic compressive pressure. The formation of new bone was enhanced after implantation of the pressured complex of BM-MSCs and Bio-Oss during maxillary sinus floor elevation. The pressured complex of BM-MSCs and Bio-Oss promoted new bone formation and maturation in the rabbit maxillary sinus. Stem cell therapy combined with this tissue engineering technique could be effectively used in maxillary sinus elevation and bone regeneration. PMID:27251156

  4. Wetting in Al composites reinforced with SiC particles

    OpenAIRE

    A.C. Vieira; Rocha, L A; Gomes, J. R.

    2006-01-01

    Aluminium matrix composites have been wide used essentially due to the good relation between weight and mechanical resistance. To develop a ceramic particle/matrix interface with good characteristics, it is essential to control the interface reactivity, avoiding the formation of undesirable reaction products such as Al4C3. Essentially, there are three methods to prevent the Al4C3 formation: Si addition to Al matrix, coating of the SiC particles and to promote a passive oxidation of SiC pa...

  5. Steam reforming of methanol over a Cu/ZnO/Al 2O 3 catalyst: a kinetic analysis and strategies for suppression of CO formation

    Science.gov (United States)

    Agrell, Johan; Birgersson, Henrik; Boutonnet, Magali

    Steam reforming of methanol (CH 3OH+H 2O→CO 2+3H 2) was studied over a commercial Cu/ZnO/Al 2O 3 catalyst for production of hydrogen onboard proton exchange membrane (PEM) fuel cell vehicles. A simple power-law rate expression was fitted to experimental data in order to predict the rates of CO 2 and H 2 formation under various reaction conditions. The apparent activation energy ( Ea) was estimated to be 100.9 kJ mol -1, in good agreement with values reported in the literature. Appreciable amounts of CO by-product were formed in the reforming process at low contact times and high methanol conversions. Being a catalyst poison that deactivates the electrocatalyst at the fuel cell anode at concentrations exceeding a few ppm, special attention was paid to the pathways for CO formation and strategies for its suppression. It was found that increasing the steam-methanol ratio effectively decreases CO formation. Likewise, addition of oxygen or air to the steam-methanol mixture minimises the production of CO. By shortening the contact time and lowering the maximum temperature in the reactor, CO production can be further decreased by suppressing the reverse water-gas shift reaction.

  6. Effect of process parameters on properties of Al-Si alloys cast by Rapid Slurry Formation (RSF) technique

    International Nuclear Information System (INIS)

    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.

  7. 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.

  8. Effects of temperature and Al-concentration on formation mechanism of an aluminide coating applied on superalloy IN738LC through a single step low activity gas diffusion process

    Energy Technology Data Exchange (ETDEWEB)

    Rafiee, H., E-mail: H_rafiee@metaleng.iust.ac.i [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Arabi, H. [Center of Excellence for Advanced Materials Processing (CEAMP), School of Metallurgy and Materials Engineering, IUST (Iran, Islamic Republic of); Rastegari, S. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of)

    2010-08-27

    Effects of temperature and Al-concentration on formation mechanism of aluminide coating applied on a nickel base superalloy IN738LC via low activity gas phase aluminizing process was studied in this research. In addition, coating microstructures were investigated using optical and scanning electron microscopes; EDS and X-ray diffraction (XRD) techniques. The results showed by increasing the temperature from 850 {sup o}C to 1050 {sup o}C, formation mechanism of the coating changed. At 850 {sup o}C coating formed by inward diffusion of Al, and at 1050 {sup o}C it was initially formed by inward diffusion of Al, followed by outward diffusion of Ni. The coating layer in the sample coated at 1050 {sup o}C using low activity powder consisted of 4 wt% Al and 2 wt% activator, grown outward, while the coating obtained under other conditions grown inward. By increasing the amount of the Al from 2 wt% to 4 wt% and the activator from 1 wt% to 2 wt% in low activity powder mixture, the concentration of diffused Al in the top NiAl layer decreased sufficiently; so that the top layers gradually became rich in Ni from its interface with interdiffusion zone (IDZ). This process finally can lead to annihilation of NiAl phase rich in Al and form a layer of NiAl rich in Ni on the surface layer of the sample.

  9. Effects of temperature and Al-concentration on formation mechanism of an aluminide coating applied on superalloy IN738LC through a single step low activity gas diffusion process

    International Nuclear Information System (INIS)

    Effects of temperature and Al-concentration on formation mechanism of aluminide coating applied on a nickel base superalloy IN738LC via low activity gas phase aluminizing process was studied in this research. In addition, coating microstructures were investigated using optical and scanning electron microscopes; EDS and X-ray diffraction (XRD) techniques. The results showed by increasing the temperature from 850 oC to 1050 oC, formation mechanism of the coating changed. At 850 oC coating formed by inward diffusion of Al, and at 1050 oC it was initially formed by inward diffusion of Al, followed by outward diffusion of Ni. The coating layer in the sample coated at 1050 oC using low activity powder consisted of 4 wt% Al and 2 wt% activator, grown outward, while the coating obtained under other conditions grown inward. By increasing the amount of the Al from 2 wt% to 4 wt% and the activator from 1 wt% to 2 wt% in low activity powder mixture, the concentration of diffused Al in the top NiAl layer decreased sufficiently; so that the top layers gradually became rich in Ni from its interface with interdiffusion zone (IDZ). This process finally can lead to annihilation of NiAl phase rich in Al and form a layer of NiAl rich in Ni on the surface layer of the sample.

  10. Bispalladacycle-catalyzed Brønsted acid/base-promoted asymmetric tandem azlactone formation-Michael addition.

    Science.gov (United States)

    Weber, Manuel; Jautze, Sascha; Frey, Wolfgang; Peters, René

    2010-09-01

    Cooperative activation by a soft bimetallic catalyst, a hard Brønsted acid, and a hard Brønsted base has allowed the formation of highly enantioenriched, diastereomerically pure masked alpha-amino acids with adjacent quaternary and tertiary stereocenters in a single reaction starting from racemic N-benzoylated amino acids. The products can, for example, be used to prepare bicyclic dipeptides. PMID:20715774

  11. 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.

  12. 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.

  13. High Glucose Concentration Promotes Vancomycin-Enhanced Biofilm Formation of Vancomycin-Non-Susceptible Staphylococcus aureus in Diabetic Mice.

    Directory of Open Access Journals (Sweden)

    Chi-Yu Hsu

    Full Text Available We previously demonstrated that vancomycin treatment increased acquisition of eDNA and enhanced biofilm formation of drug-resistant Staphylococcus aureus through a cidA-mediated autolysis mechanism. Recently we found that such enhancement became more significant under a higher glucose concentration in vitro. We propose that besides improper antibiotic treatment, increased glucose concentration environment in diabetic animals may further enhance biofilm formation of drug-resistant S. aureus. To address this question, the diabetic mouse model infected by vancomycin-resistant S. aureus (VRSA was used under vancomycin treatment. The capacity to form biofilms was evaluated through a catheter-associated biofilm assay. A 10- and 1000-fold increase in biofilm-bound bacterial colony forming units was observed in samples from diabetic mice without and with vancomycin treatment, respectively, compared to healthy mice. By contrast, in the absence of glucose vancomycin reduced propensity to form biofilms in vitro through the increased production of proteases and DNases from VRSA. Our study highlights the potentially important role of increased glucose concentration in enhancing biofilm formation in vancomycin-treated diabetic mice infected by drug-resistant S. aureus.

  14. 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.

  15. 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 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. PMID:25843055

  16. AINTEGUMENTA and AINTEGUMENTA-LIKE6/PLETHORA3 Induce LEAFY Expression in Response to Auxin to Promote the Onset of Flower Formation in Arabidopsis1[OPEN

    Science.gov (United States)

    Yamaguchi, Nobutoshi; Nole-Wilson, Staci; Wagner, Doris

    2016-01-01

    Proper timing of the onset to flower formation is critical for reproductive success. Monocarpic plants like Arabidopsis (Arabidopsis thaliana) switch from production of branches in the axils of leaves to that of flowers once in their lifecycle, during the meristem identity transition. The plant-specific transcription factor LEAFY (LFY) is necessary and sufficient for this transition. Previously, we reported that the plant hormone auxin induces LFY expression through AUXIN RESPONSE FACTOR5/MONOPTEROS (ARF5/MP). It is not known whether MP is solely responsible for auxin-directed transcriptional activation of LFY. Here, we show that two transcription factors belonging to the AINTEGUMENTA-LIKE/PLETHORA family, AINTEGUMENTA (ANT) and AINTEGUMENTA-LIKE6/PLETHORA3 (AIL6/PLT3), act in parallel with MP to upregulate LFY in response to auxin. ant ail6 mutants display a delay in the meristem identity transition and in LFY induction. ANT and AIL6/PLT3 are expressed prior to LFY and bind to the LFY promoter to control LFY mRNA accumulation. Genetic and promoter/reporter studies suggest that ANT/AIL6 act in parallel with MP to promote LFY induction in response to auxin sensing. Our study highlights the importance of two separate auxin-controlled pathways in the meristem identity transition. PMID:26537561

  17. Elevated AKR1C3 expression promotes prostate cancer cell survival and prostate cell-mediated endothelial cell tube formation: implications for prostate cancer progressioan

    International Nuclear Information System (INIS)

    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. 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. 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 to promote EC tube formation. Bioinformatics

  18. 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

  19. Analysis of influence of chemical composition of Al-Si-Cu casting alloy on formation of casting defects

    Directory of Open Access Journals (Sweden)

    R. Maniara

    2007-04-01

    Full Text Available Purpose: A methodology of the computer-aided determining relationship between chemical composition of aluminum alloy and castings quality was presented in the paper.Design/methodology/approach: To resolve the problem artificial neural networks were used. Classification problems were evaluated by the consideration mainly the values of mistakes and correct answers of networks for test data. On the basis of data analyzed by the neural network, which has the best quality classification of chemical composition of tested material, the concentration of alloying elements range, which have an effect on formation casting defects, were developed to eliminate them in the future.Findings: Combining of all methods making use of chemical composition of aluminium alloy and neural networks will make it possible to achieve a better casting quality.Research limitations/implications: The presented issues may be use, among others, for manufacturers of car subassemblies from light alloys, where meeting the stringent quality requirements ensures the demanded service life of the manufactured products.Originality/value: The correctly specified number of chemical composition of aluminum alloy enables such technological process control where the number of castings defects can be reduced by means of the proper correction of the process.

  20. 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.

  1. Perilipin-mediated lipid droplet formation in adipocytes promotes sterol regulatory element-binding protein-1 processing and triacylglyceride accumulation.

    Directory of Open Access Journals (Sweden)

    Yu Takahashi

    Full Text Available Sterol regulatory element-binding protein-1 (SREBP-1 has been thought to be a critical factor that assists adipogenesis. During adipogenesis SREBP-1 stimulates lipogenic gene expression, and peroxisome proliferator-activated receptor γ (PPARγ enhances perilipin (plin gene expression, resulting in generating lipid droplets (LDs to store triacylglycerol (TAG in adipocytes. Plin coats adipocyte LDs and protects them from lipolysis. Here we show in white adipose tissue (WAT of plin-/- mice that nuclear active SREBP-1 and its target gene expression, but not nuclear SREBP-2, significantly decreased on attenuated LD formation. When plin-/- mouse embryonic fibroblasts (MEFs differentiated into adipocytes, attenuated LDs were formed and nuclear SREBP-1 decreased, but enforced plin expression restored them to their original state. Since LDs are largely derived from the endoplasmic reticulum (ER, alterations in the ER cholesterol content were investigated during adipogenesis of 3T3-L1 cells. The ER cholesterol greatly reduced in differentiated adipocytes. The ER cholesterol level in plin-/- WAT was significantly higher than that of wild-type mice, suggesting that increased LD formation caused a change in ER environment along with a decrease in cholesterol. When GFP-SREBP-1 fusion proteins were exogenously expressed in 3T3-L1 cells, a mutant protein lacking the S1P cleavage site was poorly processed during adipogenesis, providing evidence of the increased canonical pathway for SREBP processing in which SREBP-1 is activated by two cleavage enzymes in the Golgi. Therefore, LD biogenesis may create the ER microenvironment favorable for SREBP-1 activation. We describe the novel interplay between LD formation and SREBP-1 activation through a positive feedback loop.

  2. The Diaphanous-Related Formins Promote Protrusion Formation and Cell-to-Cell Spread of Listeria monocytogenes

    OpenAIRE

    Fattouh, Ramzi; Kwon, Hyunwoo; Czuczman, Mark A.; Copeland, John W.; Pelletier, Laurence; Quinlan, Margot E.; Aleixo M Muise; Higgins, Darren E.; Brumell, John H.

    2014-01-01

    The Gram-positive bacterium Listeria monocytogenes is a facultative intracellular pathogen whose virulence depends on its ability to spread from cell to cell within an infected host. Although the actin-related protein 2/3 (Arp2/3) complex is necessary and sufficient for Listeria actin tail assembly, previous studies suggest that other actin polymerization factors, such as formins, may participate in protrusion formation. Here, we show that Arp2/3 localized to only a minor portion of the protr...

  3. 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...

  4. 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

  5. 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. PMID:27044356

  6. 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)

  7. 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.

  8. 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.

  9. Carrageenan-induced inflammation promotes ROS generation and neutrophil extracellular trap formation in a mouse model of peritonitis.

    Science.gov (United States)

    Barth, Cristiane R; Funchal, Giselle A; Luft, Carolina; de Oliveira, Jarbas R; Porto, Bárbara N; Donadio, Márcio V F

    2016-04-01

    Neutrophil extracellular traps (NETs) are a combination of DNA fibers and granular proteins, such as neutrophil elastase (NE). NETs are released in the extracellular space in response to different stimuli. Carrageenan is a sulfated polysaccharide extracted from Chondrus crispus, a marine algae, used for decades in research for its potential to induce inflammation in different animal models. In this study, we show for the first time that carrageenan injection can induce NET release in a mouse model of acute peritonitis. Carrageenan induced NET release by viable neutrophils with NE and myeloperoxidase (MPO) expressed on DNA fibers. Furthermore, although this polysaccharide was able to stimulate reactive oxygen species (ROS) generation by peritoneal neutrophils, NADPH oxidase derived ROS were dispensable for NET formation by carrageenan. In conclusion, our results show that carrageenan-induced inflammation in the peritoneum of mice can induce NET formation in an ROS-independent manner. These results may add important information to the field of inflammation and potentially lead to novel anti-inflammatory agents targeting the production of NETs.

  10. 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

  11. 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.

  12. Microstructure evolution associated with adiabatic shear bands and shear band failure in ballistic plug formation in Ti-6Al-4V targets

    International Nuclear Information System (INIS)

    The microstructures and microstructure evolution associated with adiabatic shear band (ASB) formation in ballistic plugging in thick (2.5 cm) Ti-6Al-4V targets impacted by cylindrical, 4340 steel projectiles (2.0 cm in height) at impact velocities ranging from 633 m/s to 1027 m/s (just above the ballistic limit) were investigated by optical and transmission electron microscopy. ASB width increased from 10 μm to 21 μm as the velocity increased. ASB evolution was accompanied by the evolution of dark deformation bands composed of α' martensite platelets which increased in density with increasing impact velocity. The corresponding Vickers microindentation hardness also increased from HV 619 to HV 632 in contrast to the surrounding matrix microindentation hardness of HV 555. These deformation bands were not necessarily precursors to ASB formation. The ASB average Vickers microindentation hardness was essentially constant at HV 645, a 16% increase over the matrix. This constant microindentation hardness was characterized by a consistent DRX grain structure which varied from equiaxed, defect-free grains (∼2 μm diameter) to heavily dislocated, equiaxed grains. Cracks nucleating and propagating within the ABSs were observed to increase from 8% to 87% of the ASB length with increasing impact velocity.

  13. Effect of recovery on the recrystallization texture of an Al-Mg alloy

    International Nuclear Information System (INIS)

    The effect of recovery on the recrystallization texture of an Al-Mg alloy was investigated by X-ray diffraction. It was found that the recovery of cold-rolled sheets prior to recrystallization annealing promoted the formation of the R texture, but restrained the formation of the cube texture

  14. Effect of recovery on the recrystallization texture of an Al-Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, W.C. [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Department of Chemical and Materials Engineering, University of Kentucky, 177 Anderson Hall, Lexington, KY 40506 (United States)], E-mail: wcliu@ysu.edu.cn; Li, J.; Yuan, H.; Yang, Q.X. [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2007-11-15

    The effect of recovery on the recrystallization texture of an Al-Mg alloy was investigated by X-ray diffraction. It was found that the recovery of cold-rolled sheets prior to recrystallization annealing promoted the formation of the R texture, but restrained the formation of the cube texture.

  15. The diaphanous-related formins promote protrusion formation and cell-to-cell spread of Listeria monocytogenes.

    Science.gov (United States)

    Fattouh, Ramzi; Kwon, Hyunwoo; Czuczman, Mark A; Copeland, John W; Pelletier, Laurence; Quinlan, Margot E; Muise, Aleixo M; Higgins, Darren E; Brumell, John H

    2015-04-01

    The Gram-positive bacterium Listeria monocytogenes is a facultative intracellular pathogen whose virulence depends on its ability to spread from cell to cell within an infected host. Although the actin-related protein 2/3 (Arp2/3) complex is necessary and sufficient for Listeria actin tail assembly, previous studies suggest that other actin polymerization factors, such as formins, may participate in protrusion formation. Here, we show that Arp2/3 localized to only a minor portion of the protrusion. Moreover, treatment of L. monocytogenes-infected HeLa cells with a formin FH2-domain inhibitor significantly reduced protrusion length. In addition, the Diaphanous-related formins 1-3 (mDia1-3) localized to protrusions, and knockdown of mDia1, mDia2, and mDia3 substantially decreased cell-to-cell spread of L. monocytogenes. Rho GTPases are known to be involved in formin activation. Our studies also show that knockdown of several Rho family members significantly influenced bacterial cell-to-cell spread. Collectively, these findings identify a Rho GTPase-formin network that is critically involved in the cell-to-cell spread of L. monocytogenes. PMID:25281757

  16. Small GTPases promote actin coat formation on microsporidian pathogens traversing the apical membrane of Caenorhabditis elegans intestinal cells.

    Science.gov (United States)

    Szumowski, Suzannah C; Estes, Kathleen A; Popovich, John J; Botts, Michael R; Sek, Grace; Troemel, Emily R

    2016-01-01

    Many intracellular pathogens co-opt actin in host cells, but little is known about these interactions in vivo. We study the in vivo trafficking and exit of the microsporidian Nematocida parisii, which is an intracellular pathogen that infects intestinal cells of the nematode Caenorhabditis elegans. We recently demonstrated that N. parisii uses directional exocytosis to escape out of intestinal cells into the intestinal tract. Here, we show that an intestinal-specific isoform of C. elegans actin called ACT-5 forms coats around membrane compartments that contain single exocytosing spores, and that these coats appear to form after fusion with the apical membrane. We performed a genetic screen for host factors required for actin coat formation and identified small GTPases important for this process. Through analysis of animals defective in these factors, we found that actin coats are not required for pathogen exit although they may boost exocytic output. Later during infection, we find that ACT-5 also forms coats around membrane-bound vesicles that contain multiple spores. These vesicles are likely formed by clathrin-dependent compensatory endocytosis to retrieve membrane material that has been trafficked to the apical membrane as part of the exocytosis process. These findings provide insight into microsporidia interaction with host cells, and provide novel in vivo examples of the manner in which intracellular pathogens co-opt host actin during their life cycle. PMID:26147591

  17. Multinucleation and Polykaryon Formation is Promoted by the EhPC4 Transcription Factor in Entamoeba histolytica

    Science.gov (United States)

    Cruz, Olga Hernández de la; Marchat, Laurence A.; Guillén, Nancy; Weber, Christian; Rosas, Itzel López; Díaz-Chávez, José; Herrera, Luis; Rojo-Domínguez, Arturo; Orozco, Esther; López-Camarillo, César

    2016-01-01

    Entamoeba histolytica is the intestinal parasite responsible for human amoebiasis that is a leading cause of death in developing countries. In this protozoan, heterogeneity in DNA content, polyploidy and genome plasticity have been associated to alterations in mechanisms controlling DNA replication and cell division. Studying the function of the transcription factor EhPC4, we unexpectedly found that it is functionally related to DNA replication, and multinucleation. Site-directed mutagenesis on the FRFPKG motif revealed that the K127 residue is required for efficient EhPC4 DNA-binding activity. Remarkably, overexpression of EhPC4 significantly increased cell proliferation, DNA replication and DNA content of trophozoites. A dramatically increase in cell size resulting in the formation of giant multinucleated trophozoites (polykaryon) was also found. Multinucleation event was associated to cytokinesis failure leading to abortion of ongoing cell division. Consistently, genome-wide profiling of EhPC4 overexpressing trophozoites revealed the up-regulation of genes involved in carbohydrates and nucleic acids metabolism, chromosome segregation and cytokinesis. Forced overexpression of one of these genes, EhNUDC (nuclear movement protein), led to alterations in cytokinesis and partially recapitulated the multinucleation phenotype. These data indicate for the first time that EhPC4 is associated with events related to polyploidy and genome stability in E. histolytica. PMID:26792358

  18. Multinucleation and Polykaryon Formation is Promoted by the EhPC4 Transcription Factor in Entamoeba histolytica.

    Science.gov (United States)

    Hernández de la Cruz, Olga; Marchat, Laurence A; Guillén, Nancy; Weber, Christian; López Rosas, Itzel; Díaz-Chávez, José; Herrera, Luis; Rojo-Domínguez, Arturo; Orozco, Esther; López-Camarillo, César

    2016-01-01

    Entamoeba histolytica is the intestinal parasite responsible for human amoebiasis that is a leading cause of death in developing countries. In this protozoan, heterogeneity in DNA content, polyploidy and genome plasticity have been associated to alterations in mechanisms controlling DNA replication and cell division. Studying the function of the transcription factor EhPC4, we unexpectedly found that it is functionally related to DNA replication, and multinucleation. Site-directed mutagenesis on the FRFPKG motif revealed that the K127 residue is required for efficient EhPC4 DNA-binding activity. Remarkably, overexpression of EhPC4 significantly increased cell proliferation, DNA replication and DNA content of trophozoites. A dramatically increase in cell size resulting in the formation of giant multinucleated trophozoites (polykaryon) was also found. Multinucleation event was associated to cytokinesis failure leading to abortion of ongoing cell division. Consistently, genome-wide profiling of EhPC4 overexpressing trophozoites revealed the up-regulation of genes involved in carbohydrates and nucleic acids metabolism, chromosome segregation and cytokinesis. Forced overexpression of one of these genes, EhNUDC (nuclear movement protein), led to alterations in cytokinesis and partially recapitulated the multinucleation phenotype. These data indicate for the first time that EhPC4 is associated with events related to polyploidy and genome stability in E. histolytica. PMID:26792358

  19. Fluxes of water through aquaporin 9 weaken membrane-cytoskeleton anchorage and promote formation of membrane protrusions.

    Directory of Open Access Journals (Sweden)

    Thommie Karlsson

    Full Text Available All modes of cell migration require rapid rearrangements of cell shape, allowing the cell to navigate within narrow spaces in an extracellular matrix. Thus, a highly flexible membrane and a dynamic cytoskeleton are crucial for rapid cell migration. Cytoskeleton dynamics and tension also play instrumental roles in the formation of different specialized cell membrane protrusions, viz. lamellipodia, filopodia, and membrane blebs. The flux of water through membrane-anchored water channels, known as aquaporins (AQPs has recently been implicated in the regulation of cell motility, and here we provide novel evidence for the role of AQP9 in the development of various forms of membrane protrusion. Using multiple imaging techniques and cellular models we show that: (i AQP9 induced and accumulated in filopodia, (ii AQP9-associated filopodial extensions preceded actin polymerization, which was in turn crucial for their stability and dynamics, and (iii minute, local reductions in osmolarity immediately initiated small dynamic bleb-like protrusions, the size of which correlated with the reduction in osmotic pressure. Based on this, we present a model for AQP9-induced membrane protrusion, where the interplay of water fluxes through AQP9 and actin dynamics regulate the cellular protrusive and motile activity of cells.

  20. Dok-7 promotes slow muscle integrity as well as neuromuscular junction formation in a zebrafish model of congenital myasthenic syndromes.

    Science.gov (United States)

    Müller, Juliane S; Jepson, Catherine D; Laval, Steven H; Bushby, Kate; Straub, Volker; Lochmüller, Hanns

    2010-05-01

    The small signalling adaptor protein Dok-7 has recently been reported as an essential protein of the neuromuscular junction (NMJ). Mutations resulting in partial loss of Dok-7 activity cause a distinct limb-girdle subtype of the inherited NMJ disorder congenital myasthenic syndromes (CMSs), whereas complete loss of Dok-7 results in a lethal phenotype in both mice and humans. Here we describe the zebrafish orthologue of Dok-7 and study its in vivo function. Dok-7 deficiency leads to motility defects in zebrafish embryos and larvae. The relative importance of Dok-7 at different stages of NMJ development varies; it is crucial for the earliest step, the formation of acetylcholine receptor (AChR) clusters in the middle of the muscle fibre prior to motor neuron contact. At later stages, presence of Dok-7 is not absolutely essential, as focal and non-focal synapses do form when Dok-7 expression is downregulated. These contacts however are smaller than in the wild-type zebrafish, reminiscent of the neuromuscular endplate pathology seen in patients with DOK7 mutations. Intriguingly, we also observed changes in slow muscle fibre arrangement; previously, Dok-7 has not been linked to functions other than postsynaptic AChR clustering. Our results suggest an additional role of Dok-7 in muscle. This role seems to be independent of the muscle-specific tyrosine kinase MuSK, the known binding partner of Dok-7 at the NMJ. Our findings in the zebrafish model contribute to a better understanding of the signalling pathways at the NMJ and the pathomechanisms of DOK7 CMSs. PMID:20147321

  1. 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.

  2. 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.

  3. 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.

  4. Effects of MgO and Al2O3 additions on the formation of the high Tc phase and superconducting properties in the Bi-Pb-Sr-Ca-Cu-O ceramic systems

    International Nuclear Information System (INIS)

    This paper reports on the effects of addition of different amounts of MgO and Al2O3 to the starting composition of BPSCCO ceramic superconductors that have been analyzed by means of X-ray diffraction, magnetic measurements, SE and EDS. The results show that the superconducting properties of BPSCC are not directly influenced by the addition. The presence of Al2O3 induces, however, the formation of a new Al-rich paramagnetic phase which modifies the effective starting stoichiometry increasing sample contamination by copper oxide and calcium cuprate

  5. TiO2 and Al2O3 promoted Pt/C nanocomposites as low temperature fuel cell catalysts for electro oxidation of methanol in acidic media

    International Nuclear Information System (INIS)

    Carbon corrosion and platinum dissolution are the two major catalyst layer degradation problems in polymer electrolyte membrane fuel cells (PEMFC). Ceramic addition can reduce the corrosion of carbon and increase the stability of catalysts. Pt/TiO2, Pt/TiO2-C, Pt/Al2O3 and Pt/Al2O3-C catalysts were synthesized and characterized. Electrochemical surface area of Pt/TiO2-C and Pt/Al2O3-C nanocomposite catalysts was much higher than the Pt/TiO2 and Pt/Al2O3 catalysts. Peak current, specific activity and mass activity of the catalysts was also determined by cyclic voltammetry and were much higher for the carbon nanocomposites. Exchange current densities were determined from Tafel plots. Heterogeneous rates of reaction of electro oxidation of methanol were determined for all the catalysts and were substantially higher for titania catalysts as compared to alumina added catalysts. Mass activity of Pt/TiO2-C was much higher than mass activity of Pt/Al2O3-C. Stability studies showed that addition of ceramics have increased the catalytic activity and durability of the catalysts considerably

  6. C-H activation versus yttrium-methyl cation formation from [Y(AlMe4)3] induced by cyclic polynitrogen bases: solvent and substituent-size effects.

    Science.gov (United States)

    Bojer, Daniel; Venugopal, Ajay; Mix, Andreas; Neumann, Beate; Stammler, Hans-Georg; Mitzel, Norbert W

    2011-05-23

    The reaction of 1,3,5-triisopropyl-1,3,5-triazacyclohexane (TiPTAC) with [Y(AlMe(4))(3)] resulted in the formation of [(TiPTAC)Y(Me(3)AlCH(2)AlMe(3))(μ-MeAlMe(3))] by C-H activation and methane extrusion. In contrast, the presence of bulkier cyclohexyl groups on the nitrogen atoms in 1,3,5-tricyclohexyl-1,3,5-triazacyclohexane (TCyTAC) led to the formation of the cationic dimethyl complex [(TCyTAC)(2)YMe(2)][AlMe(4)]. The investigations reveal a dependency of the reaction mechanism on the steric bulk of the N-alkyl entity and the solvent employed. In toluene C-H activation was observed in reactions of [Y(AlMe(4))(3)] with 1,3,5-trimethyl-1,3,5-triazacyclohexane (TMTAC) and TiPTAC. In THF molecular dimethyl cations, such as [(TCyTAC)(2)YMe(2)][AlMe(4)], [(TMTAC)(2)YMe(2)][AlMe(4)] and [(TiPTAC)(2)YMe(2)][AlMe(4)], could be synthesised by addition of the triazacyclohexane at a later stage. The THF-solvated complex [YMe(2)(thf)(5)][AlMe(4)] could be isolated and represents an intermediate in these reactions. It shows that cationic methyl complexes of the rare-earth metals can be formed by donor-induced cleavage of the rare-earth-metal tetramethylaluminates. The compounds were characterised by single-crystal X-ray diffraction or multinuclear and variable-temperature NMR spectroscopy, as well as elemental analyses. Variable-temperature NMR spectroscopy illustrates the methyl group exchange processes between the cations and anions in solution. PMID:21503986

  7. Effect of Bi promoter on the performances of selective oxidation of isobutane to methacrolein over MoVO/AlPO4 catalysts

    Institute of Scientific and Technical Information of China (English)

    Xitao Wang; Mei Li; Fen Wang; Shunhe Zhong; Shi Jiang; Sihe Wang

    2012-01-01

    The effects of Bi on the catalytic performance of selective oxidation of isobutane to methacrolein over MoVO/AlPO4 catalyst were investigated by XRD,FT-Raman,XPS,UV-vis DRS techniques.The results show that the addition of Bi component into the MoVO/AlPO4 catalyst obviously improves the catalytic performance,and the selectivity to methacrolein can increase from 14.2% to 45.1% with the increase of Bi/V molar ratio from 0 to 1.Combining the characterization results with the reaction evaluation,it is concluded that the catalytic activities of the MoV0.3Bix/AlPO4 catalysts are related to the crystalline phase composition and the dispersion of molybdenum and vanadium oxides species in general,and also to the V5+/V4+ molar ratio on the surface in particular.

  8. Direct measurements of reversible free-volume formation in bulk Zr56Al7Cu24Ni10Co3 glass below the glass transition temperature

    International Nuclear Information System (INIS)

    Full text: Most models regarding the glass transition are based on information obtained from the supercooled liquid state, either by experiment or by simulation. The slowing down of molecular or atomic motion occurring at the glass transition makes the kinetics difficult to access for common measurement techniques at lower temperatures. However, possible changes around Tg regarding the structural dynamics are believed to yield key parameters in understanding the glass transition. We report the measurement of thermally activated reversible formation and disappearance of free volume in bulk Zr56Al7Cu24Ni10Co3 glass by means of high-resolution laser dilatometry in the lower temperature regime around the glass transition. The measurement technique involving a 2-beam Michelson laser-interferometer is contactless and allows access to time constants of up to 1 x 106 s. From isothermal length change measurements at different temperatures after fast temperature changes the underlying atomic processes were studied. According to a rst analysis the behavior can be described by an Arrhenius relation with high activation energy. (author)

  9. 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.

  10. 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.

  11. A study on the orientation inheritance in laminated NiAl produced by in situ reaction annealing.

    Science.gov (United States)

    Du, Yan; Fan, Guohua; Geng, Lin

    2016-04-01

    In order to promote the performance of B2 NiAl by texture control of orientation during in situ processing, phase transformation in laminated NiAl with bimodal grain size distribution manufactured by reaction annealing of Ni and Al foils has been studied. It turned out that there existed a Kurdjumov-Sachs orientation relationship (K-S OR) between parent Ni and product NiAl by crystallography analysis according to the electron backscatter diffraction (EBSD) results. The parent Ni did not transform to the product NiAl directly but via the formation of Ni3Al firstly according to the transmission electron microscope (TEM) observation of the interface. This led to a new K-S OR between Ni3Al and NiAl with a small atomic misfit, which made less residual stress generated through the formation of Ni3Al than directly from the parent Ni. PMID:26867210

  12. Combination coating of chitosan and anti-CD34 antibody applied on sirolimus-eluting stents can promote endothelialization while reducing neointimal formation

    Directory of Open Access Journals (Sweden)

    Yang Feng

    2012-10-01

    Full Text Available Abstract Background Circulating endothelial progenitor cells (EPCs capture technology improves endothelialization rates of sirolimus-eluting stents (SES, but the problem of delayed re-endothelialization, as well as endothelial dysfunction, has still not been overcome. Therefore, we investigated whether the combination coating of hyaluronan-chitosan (HC and anti-CD34 antibody applied on an SES (HCASES can promote endothelialization, while reducing neointimal formation and inflammation. Methods Sirolimus-eluting stents(SES, anti-CD34 antibody stents (GS and HC-anti-CD34 antibody combined with sirolimus-eluting stents (HCASES were deployed in 54 normal porcine arteries and harvested for scanning electron microscopy (SEM and histological analysis. The ratio of endothelial coverage above the stents was evaluated by SEM analysis at 7, 14 and 28 days. The percentage of in-stent stenosis was histologically analyzed at 14 and 28 days. Results SEM analysis at 7 days showed that endothelial strut coverage was increased in the HCASES group (68±7% compared with that in the SES group (31±4%, p=0.02. At 14 days, stent surface endothelialization, evaluated by SEM, showed a significantly higher extent of endothelial coverage above struts in the GS (95 ± 2% and the HCASES groups (87±4% compared with that in the SES group (51±6%, p=0.02. Histological examination showed that the percentage of stenosis in the HCASES group was not significantly different to that of the SES and GS groups (both p> 0.05. At 28 days, there was no difference in the rates of endothelial coverage between the HCASES and GS groups. The HCASES group showed less stenosis than that in the GS group (P Conclusions SEM and histology demonstrated that HCASESs can promote re-endothelialization while enhancing antiproliferative effects.

  13. Effects of temperature and Al-concentration on formation mechanism of an aluminide coating applied on super alloy IN738LC through a single-step high activity gas diffusion process

    International Nuclear Information System (INIS)

    Formation mechanism of an aluminide coating on a nickel base superalloy IN738LC via a single step high activity gas diffusion process has been investigated in this research. Effects of coating temperature and aluminum concentration in powder mixture on formation mechanism were studied using optical and scanning electron microscopes, energy-dispersive X-ray spectroscopy and X-ray diffraction techniques. For this purpose two different packs containing 1 and 2 wtpercentaluminum powder, were used for coating the samples at two temperatures, 850degreeC and l050degreeC. The ratio of Al to activator was kept constant in both packs. By increasing the Al content in high activity powder mixture, the concentration of diffused Al increased in the coating layers, and the thickness of coating increased. At 1050degreeC as the rate of diffused Al to the interdiffusion zone increased, this zone gradually transformed to outer coating phases. At 850degreeC coating formed by inward diffusion of Al, but at 1050degreeC it was initially formed by inward diffusion of Al followed by outward diffusion of Ni.

  14. 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.

  15. 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.

  16. Effect of rotating magnetic field and manganese on the formation of iron-containing intermetallic compounds in Al-Si alloy

    OpenAIRE

    Zhang, Yumeng; Svynarenko, K; Zou, Q; Jie, J; Li, Tianyi

    2015-01-01

    International audience The acicular β-AlSiFe phase is common but detrimental iron-containing intermetallic phase in Al-Si alloys. In this study, rotating magnetic field (RMF) and manganese neutralizer were used to modify the β-phase in Al-12%Si-2%Fe alloy. The results showed that the manganese addition caused the morphological transformation of iron phase from β-AlFeSi to α-AlSiFeMn with the relation of transition rate to the manganese content. The total transformation was only achieved wh...

  17. Investigation of promoted Cu/ZnO/Al{sub 2}O{sub 3} methanol steam reforming nanocatalysts by full factorial design

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi Pajaie, H.; Taghizadeh, M. [Babol University of Technology, Chemical Engineering Department, Babol (Iran, Islamic Republic of)

    2012-10-15

    A Cu/ZnO/Al{sub 2}O{sub 3} nanocatalyst was applied for hydrogen production via steam reforming of methanol in a fixed-bed reactor. Modified forms of the catalyst were prepared by adding small amounts of Ba, Zr, and Ce oxides. The catalysts were characterized by means of N{sub 2} adsorption-desorption, X-ray diffraction, and scanning electron microscope techniques. Full factorial design was used to optimize the required number of experiments and evaluate the catalytic activity in a fixed-bed reactor. The oxide additives reduced the production of carbon monoxide and increased the selectivity of carbon dioxide as well as the yield of hydrogen production. Among the studied catalysts, the Cu/ZnO/Al{sub 2}O{sub 3}/CeO{sub 2}/ZrO{sub 2} catalyst presented the best performance. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Influence of Grain-Refiner Addition on the Morphology of Fe-Bearing Intermetallics in a Semi-Solid Processed Al-Mg-Si Alloy

    Science.gov (United States)

    Smith, Tahsina; O'Reilly, Keyna; Kumar, Sundaram; Stone, Ian

    2013-11-01

    The three-dimensional morphologies of the Fe-bearing intermetallics in a semisolid-processed Al-Mg-Si alloy were examined after extracting the intermetallics. α c-AlFeSi and β-AlFeSi are the major Fe-bearing intermetallics. Addition of Al-Ti-B grain refiner typically promotes β-AlFeSi formation. β-AlFeSi was observed with a flat, plate-like morphology with angular edges in the alloy with and without grain refiner, whereas α c-AlFeSi was observed as "flower"-like morphology in the alloy with grain refiner.

  19. Health-promoting Lifestyle and its Demographic Predictors in Infertile Couples Referred to Infertility Clinic of Tabriz Al-Zahra Hospital, 2013

    OpenAIRE

    Mirghafourvand, Mojgan; Sehhati, Fahimeh; Rahimi, Mareieh

    2014-01-01

    Introduction: Improving the lifestyle of infertile couples led to the preservation of their performance, increase their quality of life, and reduce health cost. So, the aims of this study were to determine the health-promoting lifestyle and its predictors among infertile couples. Methods: In a cross-sectional, analytical study 322 infertile couples referred to an infertility clinic in Tabriz was participated with convenience sampling method. The demographic and the standard ...

  20. 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.

  1. Capturing metal-support interactions in situ during the reduction of a Re promoted Co/γ-Al2O3 catalyst

    DEFF Research Database (Denmark)

    Tsakoumis, N. E.; Johnsen, Rune E.; van Beek, W.;

    2016-01-01

    cations into the structure of the support. The non-linear cell expansion coincided with the formation of a CoO phase. In addition, space resolved diffraction at the inlet and the outlet of the reactor evidenced a negative effect of the partial pressure of indigenous H2O(g) on the reduction process....

  2. 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.

  3. Hypoxia promotes the formation of Cryptococcus neoformans biofilms%低氧对新生隐球菌生物膜的影响

    Institute of Scientific and Technical Information of China (English)

    李宗辉; 孔庆涛; 杜雪; 邓琳; 胡治丽; 桑红

    2015-01-01

    Objective There is a lack of information on the effect of hypoxia on the virulence of Cryptococcus neoformans . This study was to construct a Cryptococcus neoformans bilfilm model in vitro and observe the influence of hypoxia on the biofilm forma-tion. Methods We constructed a Cryptococcus neoformans biofilm model in vitro in 24-well and 96-well microculture plates using DMEM culture medium at the oxygen concentrations of 21%( normoxia ) and 1% ( hypoxia ) .We collected the Cryptococcus neofor-mans biofilms at 2, 4, 8, 12, 24, 48, and 72 hours after culturing and observed their thickness , structure, and growth activity in the two different oxygen conditions by light microscopy , confocal laser scanning microscopy , and MTT assay . Results The Cryptococcus neoformans biofilm model was successfully constructed in the conditions of both hypoxia and normoxia .The processes of biofilm forma-tion in the two conditions were similar , involving adhesion , aggregation , micro-colony formation , and biofilm maturation , with the ulti-mate biofilm thickness of about 16 μm.The cell density and growth activity of the biofilms increased with the extension of incubation time, gradually stabilized with their maturity , and both were relatively higher at 1%than at 21%oxygen concentration . Conclusion The abilities of Cryptococcus neoformans biofilm formation vary with different oxygen concentrations , and hypoxia can promote the for-mation of Cryptococcus neoformans biofilms .%目的:低氧对新生隐球菌毒力因子的影响尚不清楚。探讨低氧浓度对新生隐球菌生物膜形成的影响。方法采用DMEM培养基24孔板、96孔板培养的方法分别在正常氧浓度(21%)和1%氧浓度培养条件下建立生物膜体外模型;分别在2、4、8、12、24、48、72 h取新生隐球菌生物膜用光学显微镜、共聚焦激光扫描显微镜、MTT等方法观察2组氧浓度下新生隐球菌生物膜形成厚度、形态、生长动力学等指

  4. 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%.

  5. 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.

  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. Overexpression of angiopoietin 2 promotes the formation of oral squamous cell carcinoma by increasing epithelial-mesenchymal transition-induced angiogenesis.

    Science.gov (United States)

    Li, C; Li, Q; Cai, Y; He, Y; Lan, X; Wang, W; Liu, J; Wang, S; Zhu, G; Fan, J; Zhou, Y; Sun, R

    2016-09-01

    Oral squamous cell carcinoma (OSCC) is the most common cancer of the head and neck and is associated with a high rate of lymph node metastasis. The initial step in the metastasis and transition of tumors is epithelial-mesenchymal transition (EMT)-induced angiogenesis, which can be mediated by angiopoietin 2 (ANG2), a key regulatory factor in angiogenesis. In the present study, immunohistochemistry and real-time quantitative reverse transcriptase (qRT-PCR) were used to measure the expression of ANG2 in OSCC tissues. Plasmids encoding ANG2 mRNA were used for increased ANG2 expression in the OSCC cell line TCA8113. The short interfering RNA (siRNA)-targeting ANG2 mRNA sequences were used to inhibit ANG2 expression in TCA8113 cells. Subsequently, transwell assays were performed to examine the effects of ANG2 on TCA8113 cell migration and invasion. Furthermore, in vivo assays were performed to assess the effect of ANG2 on tumor growth. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays and immunohistochemistry were used to examine cell apoptosis and angiogenesis in tumor tissues, respectively. Finally, western blot analysis was performed to evaluate tumor formation-related proteins in OSCC tissues. We found that protein expression of ANG2 was remarkably upregulated in OSCC tissues. Overexpression of ANG2 increased the migration and invasion of TCA8113 cells by regulating EMT. Further investigations showed that overexpression of ANG2 increased tumor growth in nude mice, and angiogenesis of OSCC tissues increased in the presence of ANG2 overexpression. Overexpression of ANG2 also reduced cell apoptosis in tumor tissue cells. Finally, we found that overexpression of ANG2 resulted in changes in the expression of tumor formation-related proteins including vimentin, E-cadherin, Bim, PUMA, Bcl-2, Bax, Cyclin D1, PCNA and CD31. Our findings show that ANG2 has an important role in the migration and invasion of OSCC. More importantly, further

  8. 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

  9. 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.

  10. The formation and characteristics of the i-motif structure within the promoter of the c-myb proto-oncogene.

    Science.gov (United States)

    Li, Huihui; Hai, Jinhui; Zhou, Jiang; Yuan, Gu

    2016-09-01

    C-myb proto-oncogene is a potential therapeutic target for some human solid tumors and leukemias. A long cytosine-rich sequence, which locates the downstream of the transcription initiation site, is demonstrated to fold into an intramolecular i-motif DNA using electrospray ionization mass spectrometry (ESI-MS) and circular dichroism (CD) spectroscopy. Effects of factors, including the pH value, the number of C:C(+) dimers, the concentration of buffer, the molecular crowding condition, and the coexistence of the complementary DNA, on the formation and the structural stability of the i-motif DNA are systematically studied. We have demonstrated that the i-motif folding in the c-myb promoter could be accelerated upon synergistic physiological stimuli including intracellular molecular crowding and low pH values, as well as the large number of the i-motif C:C(+) dimers. Meanwhile, various inputs, such as acids/bases and metal ions, have exhibited their abilities in controlling the conformational switch of the c-myb GC-rich DNA. Acidic pH values and the presence of K(+) ions can induce the dissociation of the double helix. Our present strategy can greatly extend the potential usages of i-motif DNA molecules with specific sequences as conformational switch-controlled devices. Moreover, this work demonstrates the superiority of CD spectroscopy associated with ESI-MS as a rapid, more cost-effective and sensitive structural change responsive method in the research of DNA conformational switching. PMID:27487467

  11. 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.

  12. Daintain/AIF-1 Plays Roles in Coronary Heart Disease via Affecting the Blood Composition and Promoting Macrophage Uptake and Foam Cell Formation

    Directory of Open Access Journals (Sweden)

    Junhan Wang

    2013-07-01

    Full Text Available Background: Daintain/AIF-1 is an inflammatory polypeptide factor/allograft inflammatory factor 1 derived from macrophages. It is characterized in APOE-/- mice as a novel inflammatory factor associated with atherosclerosis. The purpose of this study was to characterize its function in human atherosclerosis. Methods: Immunohistochemistry was used to identify the expression of daintain/AIF-1 in vessel segments within and far from atherosclerotic plaques; High-performance liquid chromatography (HPLC was used to display the effects of daintain/AIF-1 on C-reactive protein (CRP, oxidative capacity and superoxide dismutase (SOD in vivo; Oil Red O Staining was used to show the effects of daintain/AIF-1 on uptake of oxidized low density lipoprotein (ox-LDL into U937 cells, a macrophage line; Western Blot was used to test scavenger receptor A (SRA expression. Results: A high density of daintain/AIF-1 was observed in the tunica intima and media of coronary artery with atherosclerotic plaque, and fewer daintain/AIF-1 in the vessels without atherosclerotic plaque; Daintain/AIF-1 injected intravenously into BALB/c mice boosted oxidative capacity, significantly impaired SOD activities and augmented the CRP level in blood. According to the oil red O test, daintain/AIF-1 profoundly facilitated the uptake of ox-LDL in U937 macrophages and formation of foam cells in the endothelium. We also found that the molecular mechanisms are effective by promoting overexpression of SRA on macrophages. Conclusion: These findings implicate that the inflammatory factor daintain/AIF-1 is closely associated with atherogenesis, and could be further characterized as a novel risk factor for atherosclerosis

  13. Processing and oxidation of co-deposited Ni-Al coatings

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yue-bo; PENG Xiao; WANG Fu-hui

    2004-01-01

    Electrodeposited Ni matrix/Al microparticles or nanoparticles dispersed composite coatings (termed as EMCCs or ENCCs) are developed from a Ni-based electrolyte bath. The Al microparticles are in a size range of 1 -5 μm and the Al nanoparticles in an average size of 75 nm. The Al content in coatings increases with increase in the particle content in the bath. Particle size effect on the degree of codeposition is not significant. However, codeposition of Al nanoparticles instead of microparticles promotes more homogenous growth of Ni deposits on {111}, {200} and {220} planes. The oxidation at 1 050 ℃ of the as-deposited composite coatings shows that at a comparable Al content, ENCC of Ni-Al exhibits a better oxidation resistance than EMCC of Ni-Al due to the fast formation of an alumina scale during the transient stage of oxidation.

  14. Formation of Bidisperse Particle Clouds

    Science.gov (United States)

    Er, Jenn Wei; Zhao, Bing; Law, Adrian W. K.; Adams, E. Eric

    2014-11-01

    When a group of dense particles is released instantaneously into water, their motion has been conceptualized as a circulating particle thermal (Ruggerber 2000). However, Wen and Nacamuli (1996) observed the formation of particle clumps characterized by a narrow, fast moving core shedding particles into wakes. They observed the clump formation even for particles in the non-cohesive range as long as the source Rayleigh number was large (Ra > 1E3) or equivalently the source cloud number (Nc) was small (Nc < 3.2E2). This physical phenomenon has been investigated by Zhao et al. (2014) through physical experiments. They proposed the theoretical support for Nc dependence and categorized the formation processes into cloud formation, transitional regime and clump formation. Previous works focused mainly on the behavior of monodisperse particles. The present study further extends the experimental investigation to the formation process of bidisperse particles. Experiments are conducted in a glass tank with a water depth of 90 cm. Finite amounts of sediments with various weight proportions between coarser and finer particles are released from a cylindrical tube. The Nc being tested ranges from 6E-3 to 9.9E-2, which covers all the three formation regimes. The experimental results showed that the introduction of coarse particles promotes cloud formation and reduce the losses of finer particles into the wake. More quantitative descriptions of the effects of source conditions on the formation processes will be presented during the conference.

  15. Acidosis environment promotes osteoclast formation by acting on the last phase of preosteoclast differentiation: a study to elucidate the action points of acidosis and search for putative target molecules.

    Science.gov (United States)

    Kato, Kohtaro; Morita, Ikuo

    2011-08-01

    Acidosis promoted tartaric acid-resistant acid phosphatase-positive multinuclear cell (TRAP+MNC) or osteoclast formation. Large osteoclast or TRAP+LMNC formation was observed far more in an acidosis environment than in a physiologically neutral environment. One of the major action points of acidosis was determined to be located in the last phase of preosteoclast differentiation using a co-culture system and a soluble RANKL-dependent bone marrow cell culture system. On-going osteoclast formation in an acidosis environment markedly deteriorated when the medium was replaced with physiologically neutral medium within the first 6h; however, bone marrow cells previously stimulated in an acidosis environment for 9h differentiated into TRAP+LMNC in pH 7.4 medium. Messenger RNA (mRNA) expression levels of DC-STAMP, a key molecule in cell fusion, and NFATc1 did not increase in the acidosis environment compared with those under physiologically neutral conditions. Ruthenium red, a general TRP antagonist, deteriorated acidosis-promoted TRAP+LMNC formation. 4-Alpha-PDD, a TRPV4-specific agonist, added in the last 21 h of preosteoclast differentiation, potentiated TRAP+LMNC formation in a mild acidosis environment, showing synergism between TRPV4 activation and acidosis. RN1734, a TRPV4-specific antagonist, partly inhibited acidosis-promoted TRAP+LMNC formation. We thus narrowed down the major action points of acidosis in osteoclast formation and elucidated the characteristics of this system in detail. Our results show that acidosis effectively uses TRPV4 to drive large-scale cell fusion and also utilizes systems independently of TRPV4. PMID:21575626

  16. Stress Can Be a Good Thing for Blood Formation.

    Science.gov (United States)

    Speck, Nancy A

    2016-09-01

    Like politics, most developmental signals are local. However, in this issue of Cell Stem Cell, Kwan et al. (2016) and colleagues describe how a stress-induced signal that originates in the zebrafish brain promotes the formation of blood at a distant site, the dorsal aorta. PMID:27588740

  17. Study on the nanostructure formation mechanism of hypereutectic Al-17.5Si alloy induced by high current pulsed electron beam

    Science.gov (United States)

    Gao, Bo; Hu, Liang; Li, Shi-wei; Hao, Yi; Zhang, Yu-dong; Tu, Gan-feng; Grosdidier, Thierry

    2015-08-01

    This work investigates the nanostructure forming mechanism of hypereutectic Al-17.5Si alloy associated with the high current pulsed electron beam (HCPEB) treatment with increasing number of pulses by electron backscatter diffraction (EBSD) and SEM. The surface layers were melted and resolidified rapidly. The treated surfaces show different structural characteristics in different compositions and distribution zones. The top melted-layer zone can be divided into three zones: Si-rich, Ai-rich, and intermediate zone. The Al-rich zone has a nano-cellular microstructure with a diameter of ∼100 nm. The microstructure in the Si-rich zone consists of fine, dispersive, and spherical nano-sized Si crystals surrounded by α(Al) cells. Some superfine eutectic structures form in the boundary of the two zones. With the increase of number of pulses, the proportion of Si-rich zone to the whole top surface increases, and more cellular substructures are transformed to fine equiaxed grain. In other words, with increasing number of pulses, more Si elements diffuse to the Al-rich zone and provide heterogeneous nucleation sites, and Al grains are refined dramatically. Moreover, the relationship between the substrate Si phase and crystalline phase is determined by EBSD; that is, (1 1 1)Al//(0 0 1)Si with a value of disregistry δ at approximately 5%. The HCPEB technique is a versatile technique for refining the surface microstructure of hypereutectic Al-Si alloys.

  18. Formation of transient lamellipodia.

    Directory of Open Access Journals (Sweden)

    Juliane Zimmermann

    Full Text Available Cell motility driven by actin polymerization is pivotal to the development and survival of organisms and individual cells. Motile cells plated on flat substrates form membrane protrusions called lamellipodia. The protrusions repeatedly appear and retract in all directions. If a lamellipodium is stabilized and lasts for some time, it can take over the lead and determine the direction of cell motion. Protrusions traveling along the cell perimeter have also been observed. Their initiation is in some situations the effect of the dynamics of the pathway linking plasma membrane receptors to actin filament nucleation, e.g. in chemotaxis. However, lamellipodia are also formed in many cells incessantly during motion with a constant state of the signaling pathways upstream from nucleation promoting factors (NPFs, or spontaneously in resting cells. These observations strongly suggest protrusion formation can also be a consequence of the dynamics downstream from NPFs, with signaling setting the dynamic regime but not initiating the formation of individual protrusions. A quantitative mechanism for this kind of lamellipodium dynamics has not been suggested yet. Here, we present a model exhibiting excitable actin network dynamics. Individual lamellipodia form due to random supercritical filament nucleation events amplified by autocatalytic branching. They last for about 30 seconds to many minutes and are terminated by filament bundling, severing and capping. We show the relevance of the model mechanism for experimentally observed protrusion dynamics by reproducing in very good approximation the repetitive protrusion formation measured by Burnette et al. with respect to the velocities of leading edge protrusion and retrograde flow, oscillation amplitudes, periods and shape, as well as the phase relation between protrusion and retrograde flow. Our modeling results agree with the mechanism of actin bundle formation during lamellipodium retraction suggested by

  19. Studies on the Formation-process and the Germination-promotion of Seeds in the Bird of Paradise (Strelitzia reginae BANKS)

    OpenAIRE

    YAHIRO, Masaki; ONJÔ, Michio; ISHIHATA, Kiyotake; ヤヒロ, マサキ; オンジョウ, ミチオ; イシハタ, キヨタケ; 八尋, 正樹; 遠城, 道雄; 石畑, 清武

    1985-01-01

    Firstly, the developing-process of the capsules and the seeds in the bird ofparadise was investigated mainly in measure, and secondly, some physical andchemical treatments for germination-promotion in seeds were conducted. In the applied physical and chemical treatments, no effects of germination-promotion for seeds were recognized, excepting the conc. sulfuric acid treatments.

  20. Studies on the Formation-process and the Germination-promotion of Seeds in the Bird of Paradise (Strelitzia reginae BANKS)

    OpenAIRE

    YAHIRO, Masaki; ONJÔ, Michio; ISHIHATA, Kiyotake; ヤヒロ, マサキ; オンジョウ, ミチオ; イシハタ, キヨタケ; 八尋, 正樹; 遠城, 道雄; 石畑, 清武

    1985-01-01

    Firstly, the developing-process of the capsules and the seeds in the bird of paradise was investigated mainly in measure, and secondly, some physical and chemical treatments for germination-promotion in seeds were conducted. In the applied physical and chemical treatments, no effects of germination-promotion for seeds were recognized, excepting the conc. sulfuric acid treatments.

  1. 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.

  2. 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.

  3. 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.

  4. 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/.

  5. 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} nanoparticles showed good magnetic performances.

  6. Formation pathway, structural characterization and optimum processing parameters of synthetic topaz - Al2SiO4(OH,F)2 - by CVD

    Science.gov (United States)

    Trujillo-Vázquez, E.; Pech-Canul, M. I.

    2015-10-01

    A novel synthesis route for topaz (Al2SiO4(OH,F)2) by chemical vapor deposition (CVD) using Na2SiF6 as solid precursor was developed. Synthesis tests were conducted with and without a flow of nitrogen, positioning the Al(OH)3 substrate at 0° and 90° with respect to the gas flow direction, at 700 and 750 °C, for 60 and 90 min, respectively. It was found that topaz is synthesized through two pathways, directly and indirectly, involving a series of endothermic and exothermic, heterogeneous and homogeneous reactions between Al(OH)3 and SiF4(g). Analytical structural determination confirmed existence of orthorhombic polycrystals with lattice parameters of a =4.6558 Å, b=8.8451 Å and c=8.4069 Å. According to ANOVA, while temperature, time and interaction of substrate angular position with atmosphere (P×A) are the parameters that most significantly influence the variability in the amount of topaz formed - equivalent contributions of 31% - topaz lattice parameters are mostly impacted by the same factors (T, t, P, A), but without the interaction factor. The projected amount of topaz is in good agreement with that obtained in confirmation tests under optimal conditions: Al(OH)3 substrate compact placed at 0°, treated at 750 °C for 90 min in the absence of N2.

  7. Structured Ni catalysts on porous anodic alumina membranes for methane dry reforming: NiAl 2 O 4 formation and characterization

    KAUST Repository

    Zhou, Lu

    2015-06-29

    This communication presents the successful design of a structured catalyst based on porous anodic alumina membranes for methane dry reforming. The catalyst with a strong Ni-NiAl2O4 interaction shows both excellent activity and stability. This journal is © The Royal Society of Chemistry.

  8. Using health promotion outcomes in formative evaluation studies to predict success factors in interventions: an application to an intervention for promoting physical activity in Dutch children (JUMP-in)

    NARCIS (Netherlands)

    Jurg, M.E.; Meij, de J.S.B.; Wal, van der M.F.; Koelen, M.A.

    2008-01-01

    JUMP-in is a systematically developed intervention aimed at promoting physical activity among primary school children. It is a joint project involving different authorities and entails six school-based programme components. Measuring effects of such an intervention is a complex challenge. A common p

  9. Formation Mechanism of CaS-Bearing Inclusions and the Rolling Deformation in Al-Killed, Low-Alloy Steel with Ca Treatment

    Science.gov (United States)

    Xu, Guang; Jiang, Zhouhua; Li, Yang

    2016-08-01

    The existing form of CaS inclusion in Ca-treated, Al-killed steel during secondary refining process was investigated with scanning electron microscopy and an energy-dispersive spectrometer (EDS). The results of 12 heats industrial tests showed that CaS has two kinds of precipitation forms. One form takes place by the direct reaction of Ca and S, and the other takes place by the reaction of CaO in calcium aluminates with dissolved Al and S in liquid steel. Thermodynamic research for different precipitation modes of CaS under different temperature was carried out. In particular, CaO-Al2O3-CaS isothermal section diagrams and component activities of calcium aluminates were calculated by the thermodynamic software FactSage. By thermodynamic calculation, a precipitation-area diagram of oxide-sulfide duplex inclusion was established by fixing the sulfur content. The quantity of CaS, which was precipitated in a reaction between [Al], [S] and (CaO), can be calculated and predicted based on the precipitation-area diagram of oxide-sulfide duplex inclusion. Electron probe microanalysis and EDS were used for observing rolling deformation of different types of CaS-bearing inclusions during the rolling process. Low modification of calcium aluminates wrapped by CaS has different degrees of harm to steel in the rolling process. A thick CaS layer can prevent some fragile calcium aluminates from being crushed during the rolling process. Some oxide-sulfide duplex inclusion contains little CaS performed better deformation during the rolling process, but when CaS in oxide-sulfide duplex inclusion becomes more, it will cause the whole inclusion to lose plastic yielding ability. The plastic deformation region of CaS-bearing inclusion in a CaO-Al2O3-CaS isothermal section diagram is confirmed.

  10. Anisotropy of electrical conductivity in dc due to intrinsic defect formation in α-Al2O3 single crystal implanted with Mg ions

    Science.gov (United States)

    Tardío, M.; Egaña, A.; Ramírez, R.; Muñoz-Santiuste, J. E.; Alves, E.

    2016-07-01

    The electrical conductivity in α-Al2O3 single crystals implanted with Mg ions in two different crystalline orientations, parallel and perpendicular to c axis, was investigated. The samples were implanted at room temperature with energies of 50 and 100 keV and fluences of 1 × 1015, 5 × 1015 and 5 × 1016 ions/cm2. Optical characterization reveals slight differences in the absorption bands at 6.0 and 4.2 eV, attributed to F type centers and Mie scattering from Mg precipitates, respectively. DC electrical measurements using the four and two-point probe methods, between 295 and 490 K, were used to characterize the electrical conductivity of the implanted area (Meshakim and Tanabe, 2001). Measurements in this temperature range indicate that: (1) the electrical conductivity is thermally activated independently of crystallographic orientation, (2) resistance values in the implanted region decrease with fluence levels, and (3) the I-V characteristic of electrical contacts in samples with perpendicular c axis orientation is clearly ohmic, whereas contacts are blocking in samples with parallel c axis. When thin layers are sequentially removed from the implanted region by immersing the sample in a hot solution of nitric and fluorhydric acids the electrical resistance increases until reaching the values of non-implanted crystal (Jheeta et al., 2006). We conclude that the enhancement in conductivity observed in the implanted regions is related to the intrinsic defects created by the implantation rather than to the implanted Mg ions (da Silva et al., 2002; Tardío et al., 2001; Tardío et al., 2008).

  11. A synthetic mechano-growth factor E peptide promotes rat tenocyte migration by lessening cell stiffness and increasing F-actin formation via the FAK-ERK1/2 signaling pathway

    International Nuclear Information System (INIS)

    Tendon injuries are common in sports and are frequent reasons for orthopedic consultations. The management of damaged tendons is one of the most challenging problems in orthopedics. Mechano-growth factor (MGF), a recently discovered growth repair factor, plays positive roles in tissue repair through the improvement of cell proliferation and migration and the protection of cells against injury-induced apoptosis. However, it remains unclear whether MGF has the potential to accelerate tendon repair. We used a scratch wound assay in this study to demonstrate that MGF-C25E (a synthetic mechano-growth factor E peptide) promotes the migration of rat tenocytes and that this promotion is accompanied by an elevation in the expression of the following signaling molecules: focal adhesion kinase (FAK) and extracellular signal regulated kinase1/2 (ERK1/2). Inhibitors of the FAK and ERK1/2 pathways inhibited the MGF-C25E-induced tenocyte migration, indicating that MGF-C25E promotes tenocyte migration through the FAK-ERK1/2 signaling pathway. The analysis of the mechanical properties showed that the Young's modulus of tenocytes was decreased through treatment of MGF-C25E, and an obvious formation of pseudopodia and F-actin was observed in MGF-C25E-treated tenocytes. The inhibition of the FAK or ERK1/2 signals restored the decrease in Young's modulus and inhibited the formation of pseudopodia and F-actin. Overall, our study demonstrated that MGF-C25E promotes rat tenocyte migration by lessening cell stiffness and increasing pseudopodia formation via the FAK-ERK1/2 signaling pathway. - Highlights: • Mechano-growth factor E peptide (MGF-C25E) promotes migration of rat tenocytes. • MGF-C25E activates the FAK-ERK1/2 pathway in rat tenocytes. • MGF-C25E induces the actin remodeling and the formation of pseudopodia, and decreases the stiffness in rat tenocytes. • MGF-C25E promotes tenocyte migration via altering stiffness and forming pseudopodia by the activation of the

  12. A synthetic mechano-growth factor E peptide promotes rat tenocyte migration by lessening cell stiffness and increasing F-actin formation via the FAK-ERK1/2 signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bingyu [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Luo, Qing, E-mail: qing.luo@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Mao, Xinjian [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Xu, Baiyao [Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603 (Japan); Yang, Li [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China); Ju, Yang [Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603 (Japan); Song, Guanbin, E-mail: song@cqu.edu.cn [Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044 (China)

    2014-03-10

    Tendon injuries are common in sports and are frequent reasons for orthopedic consultations. The management of damaged tendons is one of the most challenging problems in orthopedics. Mechano-growth factor (MGF), a recently discovered growth repair factor, plays positive roles in tissue repair through the improvement of cell proliferation and migration and the protection of cells against injury-induced apoptosis. However, it remains unclear whether MGF has the potential to accelerate tendon repair. We used a scratch wound assay in this study to demonstrate that MGF-C25E (a synthetic mechano-growth factor E peptide) promotes the migration of rat tenocytes and that this promotion is accompanied by an elevation in the expression of the following signaling molecules: focal adhesion kinase (FAK) and extracellular signal regulated kinase1/2 (ERK1/2). Inhibitors of the FAK and ERK1/2 pathways inhibited the MGF-C25E-induced tenocyte migration, indicating that MGF-C25E promotes tenocyte migration through the FAK-ERK1/2 signaling pathway. The analysis of the mechanical properties showed that the Young's modulus of tenocytes was decreased through treatment of MGF-C25E, and an obvious formation of pseudopodia and F-actin was observed in MGF-C25E-treated tenocytes. The inhibition of the FAK or ERK1/2 signals restored the decrease in Young's modulus and inhibited the formation of pseudopodia and F-actin. Overall, our study demonstrated that MGF-C25E promotes rat tenocyte migration by lessening cell stiffness and increasing pseudopodia formation via the FAK-ERK1/2 signaling pathway. - Highlights: • Mechano-growth factor E peptide (MGF-C25E) promotes migration of rat tenocytes. • MGF-C25E activates the FAK-ERK1/2 pathway in rat tenocytes. • MGF-C25E induces the actin remodeling and the formation of pseudopodia, and decreases the stiffness in rat tenocytes. • MGF-C25E promotes tenocyte migration via altering stiffness and forming pseudopodia by the activation of the

  13. Promotion Effects of Nickel Catalysts of Dry Reforming with Methane

    Institute of Scientific and Technical Information of China (English)

    YAN,Zi-Feng(阎子峰); DING,Rong-Gang(丁荣刚); LIU,Xin-Mei(刘欣梅); SONG,Lin-Hua(宋林花)

    2001-01-01

    The promotion effects of nickel catalyst of dry reforming with methane were extensively investigated by means of XRD,SEM, EDX, N2-adsorption and H2-adsorption. XRD characterization indicated that good dispersion of nickel oxide and MgO promoter is achieved over γ-Al2O3 support. Addition of MgO promoter effectively retards the formation of NiS12O4 phase. SEM and EDX analysis exhibited that the addition ofrare-earth metal oxide CeO2 effectively promotes the Ni metal dispersion on the surface of the catalysts despite of undesirable self-dispersion of CeO2 promoter. Furthermore, the nickel component is gradually dispersed on the surface of the support following the exposure to reaction gas mixture for a period of time. The addition of MgO inhibited the self-dispersion and promotion effect of CeO2 on Ni dispersion on the catalysts. H2 chemisorption revealed that the addition of the alkaline oxide MgO promoter significantly prohibits the metal dispersion on the catalyst. Inappropriate promoter addition can result in sharp decrease of the metal dispersion. N2-adsorption indicated that oxide promoter was mostly concentrated on the outer layer of the alumina support while the nickel metal was generally dispersed in the support pores. Addition of promoters contributed to more reduction in mesopore volume.

  14. The roles of epithelial cell contact, respiratory bacterial interactions and phosphorylcholine in promoting biofilm formation by Streptococcus pneumoniae and nontypeable Haemophilus influenzae.

    Science.gov (United States)

    Krishnamurthy, Ajay; Kyd, Jennelle

    2014-08-01

    Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) often share a common niche within the nasopharynx, both associated with infections such as bronchitis and otitis media. This study investigated how the association between NTHi and S. pneumoniae and the host affects their propensity to form biofilms. We investigated a selection of bacterial strain and serotype combinations on biofilm formation, and the effect of contact with respiratory epithelial cells. Measurement of biofilm showed that co-infection with NTHi and S. pneumoniae increased biofilm formation following contact with epithelial cells compared to no contact demonstrating the role of epithelial cells in biofilm formation. Additionally, the influence of phosphorylcholine (ChoP) on biofilm production was investigated using the licD mutant strain of NTHi 2019 and found that ChoP had a role in mixed biofilm formation but was not the only requirement. The study highlights the complex interactions between microbes and the host epithelium during biofilm production, suggesting the importance of understanding why certain strains and serotypes differentially influence biofilm formation. A key contributor to increased biofilm formation was the upregulation of biofilm formation by epithelial cell factors.

  15. 胰岛素促进大鼠移植脂肪微血管的形成*%Insulin promotes the microvessel formation in fat grafts

    Institute of Scientific and Technical Information of China (English)

    邓颖; 曾令寰; 李伟; 吴一

    2013-01-01

    treated with hematoxylin-eosin staining and CD34 vascular staining respectively. The changes of grafted adipocytes and the growth of microvessel were observed. RESULTS AND CONCLUSION:Mature adipocytes could be observed in the hematoxylin-eosin staining sections, the size of adipocytes was smal er than that before transplantation, and part of the adipocytes were ruptured and shrinked. Hyperplasia of fibrous tissue was observed in two groups, and the number of fibrous tissue around the adipocytes in the insulin group was smal er than that in the control group. At 10 and 20 days after transplantation, the microvessel densities were (3.92±0.12) microvessels/high power field and (6.96±0.42) microvessels/high power field in the insulin group, (2.05±0.21) microvessels/high power field and (4.40±0.36) microvessels/high power field in the control group, respectively. Microvessel density in insulin group was higher than that in the control group, and there was a significant difference between two groups (P<0.01). The result shows that insulin can improve the survival rate of autogenous fat grafts by promoting the microvessel formation.

  16. Peculiarities of single track formation from TI6AL4V alloy at different laser power densities by selective laser melting

    OpenAIRE

    Yadroitsava, I.; Els, J.; Booysen, G.; Yadroitsev, Igor

    2015-01-01

    This paper describes the geometrical characteristics of single tracks manufactured by selective laser melting (SLM) at different laser powers (20-170 W) and scanning speeds (0.1-2.0 m/s). Simulation of temperature distribution during processing is carried out. A conclusion about the optimal process parameters and peculiarities of selective laser melting of Ti6Al4V alloy at low and high laser powers and scanning speeds is reached. The analysis of temperature fields creates opportunities to bui...

  17. Formation and evolution of intermetallic nanoparticles and vacancy defects under irradiation in Fesbnd Nisbnd Al ageing alloy characterized by resistivity measurements and positron annihilation

    Science.gov (United States)

    Druzhkov, A. P.; Danilov, S. E.; Perminov, D. A.; Arbuzov, V. L.

    2016-08-01

    In this paper, we study the effects of intermetallic nanoparticles like Ni3Al on the evolution of vacancy defects in the fcc Fesbnd Nisbnd Al alloy under electron irradiation using positron annihilation spectroscopy. Electrical resistivity measurements have been used as a testing method for characterizing the evolution in the underlying precipitate microstructure due to heat treatment and irradiation. It was shown that the nanosized (∼4.5 nm) intermetallic precipitates homogeneously distributed in the alloy matrix caused a several-fold decrease in the accumulation of vacancies as compared to their accumulation in the pre-quenched alloy. This effect was enhanced with the irradiation temperature. The irradiation-induced growth of intermetallic nanoparticles was also observed in the pre-quenched Fesbnd Nisbnd Al alloy under irradiation at 573 K. Thus, resistivity measurement and positron confinement in ultrafine intermetallic particles, which we revealed earlier, provided the control over the evolution of coherent precipitates, along with vacancy defects, during irradiation and annealing.

  18. Dot1-dependent histone H3K79 methylation promotes the formation of meiotic double-strand breaks in the absence of histone H3K4 methylation in budding yeast.

    Directory of Open Access Journals (Sweden)

    Mohammad Bani Ismail

    Full Text Available Epigenetic marks such as histone modifications play roles in various chromosome dynamics in mitosis and meiosis. Methylation of histones H3 at positions K4 and K79 is involved in the initiation of recombination and the recombination checkpoint, respectively, during meiosis in the budding yeast. Set1 promotes H3K4 methylation while Dot1 promotes H3K79 methylation. In this study, we carried out detailed analyses of meiosis in mutants of the SET1 and DOT1 genes as well as methylation-defective mutants of histone H3. We confirmed the role of Set1-dependent H3K4 methylation in the formation of double-strand breaks (DSBs in meiosis for the initiation of meiotic recombination, and we showed the involvement of Dot1 (H3K79 methylation in DSB formation in the absence of Set1-dependent H3K4 methylation. In addition, we showed that the histone H3K4 methylation-defective mutants are defective in SC elongation, although they seem to have moderate reduction of DSBs. This suggests that high levels of DSBs mediated by histone H3K4 methylation promote SC elongation.

  19. 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

    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......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...... energy barrier. To study the amorphous-to-quasicrystalline phase transformation kinetics in the metallic glass, relative volume fractions of the transferred quasicrystalline phase as a function of annealing time, obtained at 663, 673, 683, and 693 K, have been analyzed in details using 14 nucleation...

  20. Ru promoted cobalt catalyst on γ-Al{sub 2}O{sub 3}: Influence of different catalyst preparation method and Ru loadings on Fischer–Tropsch reaction and kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Parnian, Mohammad Javad; Taheri Najafabadi, Ali [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Mortazavi, Yadollah, E-mail: mortazav@ut.ac.ir [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Oil and Gas Processing Center of Excellence, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Khodadadi, Abbas Ali [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Oil and Gas Processing Center of Excellence, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of); Nazzari, Idin [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11155/4563, Tehran (Iran, Islamic Republic of)

    2014-09-15

    Highlights: • Effect of impregnation order and Ru content on FT reaction is reported. • Co-impregnation of Co and Ru on Al{sub 2}O{sub 3} resulted in an improved reducibility of Co. • CoRu/Al{sub 2}O{sub 3} prepared by co-impregnation method showed a better catalytic performance. • Ru does not affect C{sub 5+} selectivity whereas the activity is enhanced considerably. • Effect of synthesis parameter on rate constant and activation energy is reported. - Abstract: Ruthenium promoted cobalt catalysts supported on γ-Al{sub 2}O{sub 3} were prepared by stepwise and co-impregnation methods. The effects of impregnation order on activity and selectivity of the Fischer–Tropsch synthesis (FTS) were investigated using fixed bed microreactor. The catalysts were characterized by TPR, XRD and TEM. The selected Ru loading was 0.15 wt.% while that of Co was 15.0 wt.% in all of the prepared samples by different order of impregnation. The catalyst prepared by co-impregnation method shifted both steps of cobalt oxide reduction temperatures to lower temperatures by about 100 °C. However, temperature shift was lower for the catalyst prepared by stepwise impregnation method. The highest CO conversion and C{sub 5+} selectivity and the lowest methane selectivity were obtained for the catalyst synthesized by co-impregnation method. Two other catalysts with 0.3 and 0.6 wt.% of Ru loadings on 15.0 wt.% Co were synthesized by co-impregnation and its effect on the FTS was investigated. The prepared catalysts showed an increase in CO conversion with the increase of Ru from 0 to 0.30 wt.%. However, further increase in Ru led to lower CO conversion for a Ru loading of 0.6 wt.%. The effects of temperature and H{sub 2}/CO ratio for all catalysts were examined and their performance modeled by a Langmuir–Hinshelwood–Hougen–Watson (LHHW) rate expression.