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Sample records for aleaciones al-6si-3cu-xmg t6

  1. Quench sensitivity of hot extruded 6061-T6 and 6069-T6 aluminum alloys

    SciTech Connect

    Bergsma, S C; Kassner, M E; Li, X; Rosen, R S

    2000-08-08

    The purpose of this study is to investigate the quench sensitivity of mechanical properties of hot extruded 6061 and 6069 aluminum alloys. The relationship between mechanical properties and quench delzty time at various temperatures between 200-500 C was determined. It was concluded that the 6069-T6 was somewhat more quench sensitive than 6061, which may be consistent with the composition difference.

  2. Effect of Fatigue Crack on Static Strength: 2014-T6, 2024-T4, 6061-T6, 7075-T6 Open-Hole Monobloc Specimens

    NASA Technical Reports Server (NTRS)

    Nordmark, Glenn E.; Eaton, Ian D.

    1957-01-01

    Static tensile test results are presented for specimens of 2014-T6, 2024-T4, 6061-T6, and 7075-T6 aluminum alloy containing fatigue cracks. The results are found to be in good agreement with the results reported for similar tests from other sources. The results indicate that the presence of a fatigue crack reduced the static strength, in all cases, by an amount larger than the corresponding reduction in net area; the 6061-T6 alloy specimens were least susceptible to the crack and the 7075-T6 alloy specimens were most susceptible. It is indicated that a 7075-T6 specimen may develop as little as one-third of the expected static tensile strength when the fatigue crack was consumed only one-fourth of the original area. It was found that the static strength was substantially higher for specimens which had stop holes drilled at the end of the fatigue crack.

  3. Performance Evaluation of the T6 Ion Engine

    NASA Technical Reports Server (NTRS)

    Snyder, John Steven; Goebel, Dan M.; Hofer, Richard R.; Polk, James E.; Wallace, Neil C.; Simpson, Huw

    2010-01-01

    The T6 ion engine is a 22-cm diameter, 4.5-kW Kaufman-type ion thruster produced by QinetiQ, Ltd., and is baselined for the European Space Agency BepiColombo mission to Mercury and is being qualified under ESA sponsorship for the extended range AlphaBus communications satellite platform. The heritage of the T6 includes the T5 ion thruster now successfully operating on the ESA GOCE spacecraft. As a part of the T6 development program, an engineering model thruster was subjected to a suite of performance tests and plume diagnostics at the Jet Propulsion Laboratory. The engine was mounted on a thrust stand and operated over its nominal throttle range of 2.5 to 4.5 kW. In addition to the typical electrical and flow measurements, an E x B mass analyzer, scanning Faraday probe, thrust vector probe, and several near-field probes were utilized. Thrust, beam divergence, double ion content, and thrust vector movement were all measured at four separate throttle points. The engine performance agreed well with published data on this thruster. At full power the T6 produced 143 mN of thrust at a specific impulse of 4120 seconds and an efficiency of 64%; optimization of the neutralizer for lower flow rates increased the specific impulse to 4300 seconds and the efficiency to nearly 66%. Measured beam divergence was less than, and double ion content was greater than, the ring-cusp-design NSTAR thruster that has flown on NASA missions. The measured thrust vector offset depended slightly on throttle level and was found to increase with time as the thruster approached thermal equilibrium.

  4. Hydrostatic stress dependent yield of 7075-T6 aluminum

    SciTech Connect

    Benzley, S.E.; Priddy, T.G.; Soo Hoo, M.S.

    1980-03-01

    Tension and compression tests on notched cylindrical bars made of 7075-T6 aluminum have been conducted as a part of an investigation of the mechanics of ductile fracture. The compression tests showed significantly stiffer behavior in the nonlinear portion of the experiment than those found from the tension tests. This difference was accounted for by incorporating a hydrostatic stress dependent yield model in the analysis of the experiment. The model was verified by comparing finite element calculations with the actual experimental results.

  5. Effect of specimen thickness of fatigue-crack-growth behavior and fracture toughness of 7075-T6 and 7178-T6 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Hudson, C. M.; Newman, J. C., Jr.

    1973-01-01

    A study was made to determine the effects of specimen thickness on fatigue crack growth and fracture behavior of 7075-T6 and 7178-T6 aluminum alloy sheet and plate. Specimen thicknesses ranged from 5.1 to 12.7 mm (0.20 to 0.50 in.) for 7075-T6 and from 1.3 to 6.4 mm (0.05 to 0.25 in.) for 7178-T6. The stress ratios R used in the crack growth experiments were 0.02 and 0.50. For 7075-T6, specimen thickness had relatively little effect on fatigue-crack growth. However, the fracture toughness of the thickness of the thickest gage of 7075-T6 was about two-thirds of the fracture toughness of the thinner gages of 7075-T6. For 7178-T6, fatigue cracks generally grew somewhat faster in the thicker gages than in the thinnest gage. The fracture toughness of the thickest gage of 7178-T6 was about two-thirds of the fracture toughness of the thinner gages of 7178-T6. Stress intensity methods were used to analyze the experimental results. For a given thickness and value of R, the rate of fatigue crack growth was essentially a single-valued function of the stress intensity range for 7075-T6 and 7178-T6. An empirical equation developed by Forman, Kearney, and Engle fit the 7075-T6 and 7178-T6 crack growth data reasonably well.

  6. Effect of service usage on tensile, fatigue, and fracture properties of 7075-T6 and 7178-T6 aluminum alloys

    NASA Technical Reports Server (NTRS)

    Everett, R. A., Jr.

    1975-01-01

    A study has been made to determine the effects of extensive service usage on some basic material properties of 7075-T6 and 7178-T6 aluminum alloy materials. The effects of service usage were determined by comparing material properties for new material (generally obtained from the literature) with those for material cut from the center wing box of a C-130B transport airplane with 6385 flight-hours of service. The properties investigated were notched and unnotched fatigue strengths, fatigue-crack-growth rate, fracture toughness, and tensile properties. For the properties investigated and the parameter ranges considered (crack length, stress ratio, etc.), the results obtained showed no significant difference between service and new materials.

  7. Quantitative image analysis of WE43-T6 cracking behavior

    NASA Astrophysics Data System (ADS)

    Ahmad, A.; Yahya, Z.

    2013-06-01

    Environment-assisted cracking of WE43 cast magnesium (4.2 wt.% Yt, 2.3 wt.% Nd, 0.7% Zr, 0.8% HRE) in the T6 peak-aged condition was induced in ambient air in notched specimens. The mechanism of fracture was studied using electron backscatter diffraction, serial sectioning and in situ observations of crack propagation. The intermetallic (rare earthed-enriched divorced intermetallic retained at grain boundaries and predominantly at triple points) material was found to play a significant role in initiating cracks which leads to failure of this material. Quantitative measurements were required for this project. The populations of the intermetallic and clusters of intermetallic particles were analyzed using image analysis of metallographic images. This is part of the work to generate a theoretical model of the effect of notch geometry on the static fatigue strength of this material.

  8. Effects of Intermittent Versus Continuous Heating upon the Tensile Properties of 2024-T4, 6061-T6 and 7075-T6 Alloys

    NASA Technical Reports Server (NTRS)

    Stickley, G. W.; Anerson, H. L.

    1956-01-01

    In some applications, aluminum alloys are subjected to intermittent heating at elevated temperature. It is generally considered that the effects of such intermittent heating are cumulative, and therefore are the same as if the heating had been continuous for the same total length of time. The object of these tests was to determine the effects of intermittent and continuous heating at 300 and 400 F, for total periods of 100 and 200 hr, upon the tensile properties of 2024-T4 and 6061-T6 alloy rolled-and-drawn rod and 7075-T6 alloy extrusions, at room temperature and at the temperature of heating.

  9. Ketoprofen S(+) enantiomer inhibits prostaglandin production and cell growth in 3T6 fibroblast cultures.

    PubMed

    Sánchez, T; Moreno, J J

    1999-04-01

    The ketoprofen S(+) enantiomer inhibits with great stereoselectivity both prostaglandin H synthase isoenzymes. Thus, the biological effects of ketoprofen on inflammation are due almost entirely to the S(+) isomer. Here, we report that the S(+) enantiomer, at doses that inhibit prostaglandin synthesis, is effective in reducing DNA synthesis and 3T6 fibroblast growth. Our data suggest that prostaglandins are involved in the control of 3T6 fibroblast growth and that the effect of the ketoprofen S(+) enantiomer on 3T6 proliferation is correlated with its effects on prostaglandin H synthase and prostaglandin production. PMID:10323281

  10. Mechanical shielding reduces weld surface cracking in 6061 T6 aluminum

    NASA Technical Reports Server (NTRS)

    Hill, J. E.

    1968-01-01

    Mechanical shield of high melting point material protects 6061-T6 aluminum welded with high frequency ac tungsten arc equipment. It is held in place around the weld bead area and eliminates heat check cracks.

  11. Cloning and DNA sequence of the gene coding for Bacillus stearothermophilus T-6 xylanase.

    PubMed Central

    Gat, O; Lapidot, A; Alchanati, I; Regueros, C; Shoham, Y

    1994-01-01

    Bacillus stearothermophilus T-6 produces an extracellular thermostable xylanase. Affinity-purified polyclonal serum raised against the enzyme was used to screen a genomic library of B. stearothermophilus T-6 constructed in lambda-EMBL3. Two positive phages were isolated, both containing similar 13-kb inserts, and their lysates exhibited xylanase activity. A 3,696-bp SalI-BamHI fragment containing the xylanase gene was subcloned in Escherichia coli and subsequently sequenced. The open reading frame of xylanase T-6 consists of 1,236 bp. On the basis of sequence similarity, two possible -10 and -35 regions, a ribosome-binding site at the 5' end of the gene and a potential transcriptional termination motif at the 3' end of the gene, were identified. From the previously known N-terminal amino acid sequence of xylanase T-6 and the possible ribosome-binding site, a putative 28-amino-acid signal peptide was deduced. The mature xylanase T-6 consists of 379 amino acids with a calculated molecular weight and pI of 43,808 and 6.88, respectively. Multiple alignment of beta-glycanase amino acid sequences revealed highly conserved regions. Northern (RNA) blot analysis indicated that the xylanase T-6 transcript is about 1.4 kb and that the induction of this enzyme synthesis by xylose is on the transcriptional level. Images PMID:8031084

  12. Differential Role of the T6SS in Acinetobacter baumannii Virulence

    PubMed Central

    Foucault-Grunenwald, Marie-Laure; Borges, Vitor; Charpentier, Xavier; Limansky, Adriana S.; Gomes, João Paulo; Viale, Alejandro M.; Salcedo, Suzana P.

    2015-01-01

    Gram-negative bacteria, such as Acinetobacter baumannii, are an increasing burden in hospitals worldwide with an alarming spread of multi-drug resistant (MDR) strains. Herein, we compared a type strain (ATCC17978), a non-clinical isolate (DSM30011) and MDR strains of A. baumannii implicated in hospital outbreaks (Ab242, Ab244 and Ab825), revealing distinct patterns of type VI secretion system (T6SS) functionality. The T6SS genomic locus is present and was actively transcribed in all of the above strains. However, only the A. baumannii DSM30011 strain was capable of killing Escherichia coli in a T6SS-dependent manner, unlike the clinical isolates, which failed to display an active T6SS in vitro. In addition, DSM30011 was able to outcompete ATCC17978 as well as Pseudomonas aeruginosa and Klebsiella pneumoniae, bacterial pathogens relevant in mixed nosocomial infections. Finally, we found that the T6SS of DSM30011 is required for host colonization of the model organism Galleria mellonella suggesting that this system could play an important role in A. baumannii virulence in a strain-specific manner. PMID:26401654

  13. High strength and high ductility behavior of 6061-T6 alloy after laser shock processing

    NASA Astrophysics Data System (ADS)

    Gencalp Irizalp, Simge; Saklakoglu, Nursen

    2016-02-01

    The plastic deformation behavior of 6061-T6 alloy which was subjected to severe plastic deformation (SPD) at high strain rates during laser shock processing (LSP) was researched. In LSP-treated materials, the near surface microstructural change was examined by TEM and fracture surfaces after tensile testing were examined by SEM. An increase in strength of metallic materials brings about the decrease in ductility. In this study, the results showed that LSP-treated 6061-T6 alloy exhibited both high strength and high ductility. TEM observation showed that stacking fault (SF) ribbon enlarged, deformation twins formed and twin boundary increased in LSP-treated 6061-T6 alloy. This observation was an indication of stacking fault energy (SFE) decrease. Work hardening capability was recovered after LSP impacts.

  14. Numerical investigation on friction welding of alumina / AA 6063 T6 joints

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Velu, P. Shenbaga; Tharmaraj, R.; Kumar, R.

    2016-05-01

    Friction welding is the most suitable candidate for joining the dissimilar materials such as AA 6063 T6 alloy/Alumina for critical situations in high temperature and high corrosion resistance applications. In the present work, the numerical simulation was carried out to understand the mechanism of joining of AA 6063 T6 alloy/ Alumina rod by friction welding process. The developed thermo mechanical model is a highly nonlinear due to the interaction between the temperature fields and time dependent of the material properties. The developed numerical tool could be used to predict the temperature distribution, stress, strain and deformation of the dissimilar joints.

  15. Parametric studies on tensile strength in joining AA6061- T6 and AA7075-T6 by gas metal arc welding process

    NASA Astrophysics Data System (ADS)

    Ishak, M.; Noordin, N. F. M.; Shah, L. H.

    2015-12-01

    Proper selection of the welding parameters can result in better joining. In this study, the effects of various welding parameters on tensile strength in joining dissimilar aluminum alloys AA6061-T6 and AA7075-T6 were investigated. 2 mm thick samples of both base metals were welded by semi-automatic gas metal arc welding (GMAW) using filler wire ER5356. The welding current, arc voltage and welding speed were chosen as variables parameters. The strength of each specimen after the welding operations were tested and the effects of these parameters on tensile strength were identified by using Taguchi method. The range of parameter for welding current were chosen from 100 to 115 A, arc voltage from 17 to 20 V and welding speed from 2 to 5 mm/s. L16 orthogonal array was used to obtained 16 runs of experiments. It was found that the highest tensile strength (194.34 MPa) was obtained with the combination of a welding current of 115 A, welding voltage of 18 V and welding speed of 4 mm/s. Through analysis of variance (ANOVA), the welding voltage was the most effected parameter on tensile strength with percentage of contribution at 41.30%.

  16. Cavitation pitting and erosion of Al 6061-T6 in mineral oil and water

    NASA Technical Reports Server (NTRS)

    Rao, B. C. S.; Buckley, D. H.

    1983-01-01

    The authors are currently carrying out a study of the cavitation erosion of different bearing metals and alloys in mineral oils were studied. The variations of weight loss, the pit diameter and depth due to cavitation erosion on Al 6061-T6 in mineral oil and water are presented.

  17. Involvement of Trichoderma asperellum strain T6 in regulating iron acquisition in plants.

    PubMed

    Zhao, Lei; Wang, Fei; Zhang, Yaqing; Zhang, Jiaojiao

    2014-07-01

    Iron (Fe) deficiency is a major plant nutritional disorder in many parts of the world, particularly in areas with saline soils. Among the numerous root-associated microbes that are beneficial for plant nutrient uptake, Trichoderma spp. are the most effective rhizosphere fungi for enhancing plant growth and plant resistance to biotic and abiotic stresses. To investigate the potential mechanisms of action of Trichoderma on insoluble Fe in the soil, which is difficult for plants to absorb and utilize, a high siderophore-producing strain of Trichoderma T6, was isolated from the rhizosphere of cucumber plants. The strain was identified as T. asperellum based on the morphological features and molecular phylogenetic analyses. Applying strain T6 to sterile soil could increase soil levels of Fe(2+) and siderophores, as well as increase Fe(2+) and Fe(3+)-chelate reductase (FCR) activity in cucumber tissues. Purified siderophore eluent (PSE) increased plant growth, thus confirming its role in plant growth promotion. Moreover, extracellular Fe(3+) reducing activity and three kinds of organic acids were detected in the culture filtrate of strain T6. These results indicate that strain T6 influences plant Fe absorption in several ways. Siderophore-based Fe chelation is effective in providing Fe to plants, organic acids, and Fe(3+) reducing enzymes may participate in the solubilization and reduction of insoluble Fe(3+) to Fe(2+). PMID:24861576

  18. Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys

    SciTech Connect

    Chen, Y.C.; Feng, J.C.; Liu, H.J.

    2009-06-15

    Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys was characterized by transmission electron microscopy. In the weld nugget zone and the thermo-mechanically affected zone some metastable precipitates overaged to equilibrium phase while others solutionized into the aluminum solid solution. In the heat-affected zone the precipitates coarsened.

  19. The T6SSs of Pseudomonas aeruginosa Strain PAO1 and Their Effectors: Beyond Bacterial-Cell Targeting

    PubMed Central

    Sana, Thibault G.; Berni, Benjamin; Bleves, Sophie

    2016-01-01

    Pseudomonas aeruginosa is an opportunistic pathogen responsible for many diseases such as chronic lung colonization in cystic fibrosis patients and acute infections in hospitals. The capacity of P. aeruginosa to be pathogenic toward several hosts is notably due to different secretion systems. Amongst them, P. aeruginosa encodes three Type Six Secretion Systems (T6SS), named H1- to H3-T6SS, that act against either prokaryotes and/or eukaryotic cells. They are independent from each other and inject diverse toxins that interact with different components in the host cell. Here we summarize the roles of these T6SSs in the PAO1 strain, as well as the toxins injected and their targets. While H1-T6SS is only involved in antiprokaryotic activity through at least seven different toxins, H2-T6SS and H3-T6SS are also able to target prokaryotic as well as eukaryotic cells. Moreover, recent studies proposed that H2- and H3-T6SS have a role in epithelial cells invasion by injecting at least three different toxins. The diversity of T6SS effectors is astounding and other effectors still remain to be discovered. In this review, we present a table with other putative P. aeruginosa strain PAO1 T6SS-dependent effectors. Altogether, the T6SSs of P. aeruginosa are important systems that help fight other bacteria for their ecological niche, and are important in the pathogenicity process. PMID:27376031

  20. Antifibrotic activity of coumarins from Cnidium monnieri fruits in HSC-T6 hepatic stellate cells.

    PubMed

    Shin, Eunjin; Lee, Chul; Sung, Sang Hyun; Kim, Young Choong; Hwang, Bang Yeon; Lee, Mi Kyeong

    2011-04-01

    The CHCl(3) fraction of Cnidium monnieri fruits significantly inhibited the proliferation of hepatic stellate cells in an in-vitro assay system employing HSC-T6 hepatic stellate cell lines. Activity-guided fractionation of the CHCl(3) fraction of C. monnieri led to the isolation of ten coumarins: osthol (1), meranzin (2), auraptenol (3), meranzin hydrate (4), 7-hydroxy-8-methoxy coumarin (5), imperatorin (6), xanthotoxol (7), xanthotoxin (8), bergapten (9) and isopimpinellin (10). Of these, compounds 1 and 6 significantly inhibited proliferation of HSCs in a time- and concentration-dependent manner. In addition, compounds 1 and 6 significantly reduced collagen content in HSC-T6 cells. PMID:21082271

  1. Stir zone microstructure and strain rate during Al 7075-T6 friction stir spot welding

    NASA Astrophysics Data System (ADS)

    Gerlich, A.; Avramovic-Cingara, G.; North, T. H.

    2006-09-01

    The factors determining the temperature, heating rate, microstructure, and strain rate in Al 7075-T6 friction stir spot welds are investigated. Stir zone microstructure was examined using a combination of transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD) microscopy, while the strain rate during spot welding was calculated by incorporating measured temperatures and the average subgrain dimensions in the Zener-Hollomon relation. The highest temperature during friction stir spot welding (527 °C) was observed in spot welds made using a tool rotational speed of 3000 rpm. The stir zone regions comprised fine-grained, equiaxed, fully recrystallized microstructures. The calculated strain rate in Al 7075-T6 spot welds decreased from 650 to about 20 s-1 when the tool rotational speed increased from 1000 to 3000 rpm. It is suggested that the decrease in strain rate results when tool slippage occurs when the welding parameter settings facilitate transient local melting during the spot welding operation. Transient local melting and tool slippage are produced when the welding parameters produce sufficiently high heating rates and temperatures during spot welding. However, transient local melting and tool slippage is not produced in Al 7075-T6 spot welds made using a rotational speed of 1000 rpm since the peak temperature is always less than 475 °C.

  2. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter; Joshi, Vasant; Harris, Bryan

    2009-06-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250^oC. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D1 = 0.110, D2 = 0.573, D3= -3.4446, D4 = 0.016, and D 5= 1.099 and Al7075-T6; D1= 0.451 D2= -0.952 D3= -.068, D4 =0.036, and D5 = 0.697.

  3. Functional performance of the T-6A Texan (JPATS) CFIS laser detonator

    NASA Astrophysics Data System (ADS)

    Blachowski, Thomas J.; Thom, Travis

    2010-08-01

    The Indian Head Division, Naval Surface Warfare Center (IHD NSWC) CAD Engineering Division is conducting a program to evaluate the laser and energetic components which comprise the Canopy Fracturing Initiation System (CFIS). This system is currently installed on the T-6A Texan II or JPATS (Joint Primary Aircraft Training System) aircraft. The T-6A Texan II is the first aircraft used by the military to train future pilots. The CFIS is an element of the pilot emergency escape system which weakens the canopy in the path of the ejection seat. The CFIS is comprised of three differing laser configurations (Internal, External, and Seat Motion) which generate a pulse that is distributed through a fiber optic energy transmission system. This pulse, in turn, initiates one of the system's explosive components, a detonator (specifically, the CCU-158/A Laser Initiated Detonator). This detonator transfers the signal to the remaining energetic components that, in turn, function to weaken their respective canopies. All of the CFIS laser types are flashlamp-pumped, neodymium glass lasers which are located at various positions in the aircraft cockpit area. This paper builds on the previous SPIE papers (2008 - Conference 7070 and 2009 - Conference 7434, respectively) and presents the initial functional test results for the CFIS Laser Detonator. These functional test results provide the technical support to justify the useful lifetime of this energetic component while being installed in the T-6A Texan II aircraft under operational conditions.

  4. Global translational impacts of the loss of the tRNA modification t6A in yeast

    PubMed Central

    Thiaville, Patrick C.; Legendre, Rachel; Rojas-Benítez, Diego; Baudin-Baillieu, Agnès; Hatin, Isabelle; Chalancon, Guilhem; Glavic, Alvaro; Namy, Olivier; de Crécy-Lagard, Valérie

    2016-01-01

    The universal tRNA modification t6A is found at position 37 of nearly all tRNAs decoding ANN codons. The absence of t6A37 leads to severe growth defects in baker’s yeast, phenotypes similar to those caused by defects in mcm5s2U34 synthesis. Mutants in mcm5s2U34 can be suppressed by overexpression of tRNALysUUU, but we show t6A phenotypes could not be suppressed by expressing any individual ANN decoding tRNA, and t6A and mcm5s2U are not determinants for each other’s formation. Our results suggest that t6A deficiency, like mcm5s2U deficiency, leads to protein folding defects, and show that the absence of t6A led to stress sensitivities (heat, ethanol, salt) and sensitivity to TOR pathway inhibitors. Additionally, L-homoserine suppressed the slow growth phenotype seen in t6A-deficient strains, and proteins aggregates and Advanced Glycation End-products (AGEs) were increased in the mutants. The global consequences on translation caused by t6A absence were examined by ribosome profiling. Interestingly, the absence of t6A did not lead to global translation defects, but did increase translation initiation at upstream non-AUG codons and increased frame-shifting in specific genes. Analysis of codon occupancy rates suggests that one of the major roles of t6A is to homogenize the process of elongation by slowing the elongation rate at codons decoded by high abundance tRNAs and I34:C3 pairs while increasing the elongation rate of rare tRNAs and G34:U3 pairs. This work reveals that the consequences of t6A absence are complex and multilayered and has set the stage to elucidate the molecular basis of the observed phenotypes. PMID:26798630

  5. Supernova Simulations from the T-6 Group at Los Alamos National Laboratory (LANL)

    DOE Data Explorer

    Woosley, Stanford

    LANL's primary effort to numerically model supernova explosions is based in the Theoretical Astrophysics Group (T-6). Both thermonuclear supernovae and core- collapse supernovae are studied, with special emphasis placed on multi-dimensional simulations. Both types of supernova require a wide range of input physics, which is provided by research efforts throughout the lab. In particular this research benefits from other LANL efforts studying massive star evolution, equations of state and aspects of neutrino physics. [From http://laastro.lanl.gov/science/computation.html

  6. Differentiation of A31T6 proadipocytes to adipocytes: A flow cytometric analysis

    SciTech Connect

    Smyth, M.J.; Wharton, W. )

    1992-03-01

    A flow cytometric assay has been developed which provides precise, quantitative information on the accumulation of cytoplasmic triglycerides in individual A31T6 proadipocytes as they differentiate into adipocytes. The opportunity to measure multiple optical parameter on a cell-by-cell basis has enabled us to monitor phenotypic aspects of differentiation with a greater level of sensitivity than was previously possible. Using the fluorescent hydrophobic probe, Nile red, they have found that as a cell proceeds along the differentiation pathway, the gold fluorescence signal from the cell increases, reflecting the accumulation of cytoplasmic lipid droplets. They have determined (1) the presence of an undifferentiated population of cells whose existence is not detected by conventional phase microscopy, (2) that insulin is no required to drive differentiation in this system, (3) that exposure to a combination of insulin and dexamethasone results in a lower accumulation of lipid in a cell than does exposure to either agent alone, and (4) that A31T6 cells show the same response to differentiation-promoting agents whether applied at the time of plating or at confluence.

  7. Purification and characterization of a thermostable xylanase from Bacillus stearothermophilus T-6.

    PubMed Central

    Khasin, A; Alchanati, I; Shoham, Y

    1993-01-01

    Bacillus stearothermophilus T-6 produces an extracellular xylanase that was shown to optimally bleach pulp at pH 9 and 65 degrees C. The enzyme was purified and concentrated in a single adsorption step onto a cation exchanger and is made of a single polypeptide with an apparent M(r) of 43,000 (determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Xylanase T-6 is an endoxylanase that completely degrades xylan to xylose and xylobiose. The pIs of the purified protein were 9 and 7 under native and denaturing conditions, respectively. The optimum activity was at pH 6.5; however, 60% of the activity was still retained at pH 10. At 65 degrees C and pH 7, the enzyme was stable for more than 10 h; at 65 degrees C and pH 9, the half-life of the enzyme was approximately 6 h. Kinetic experiments at 55 degrees C gave Vmax and Km values of 288 U/mg and 1.63 mg/ml, respectively. The enzyme had no apparent requirement for cofactors, and its activity was strongly inhibited by Zn2+, Cd2+, and Hg2+. Xylan completely protected the protein from inactivation by N-bromosuccinimide. The N-terminal sequence of the first 45 amino acids of the enzyme showed high homology with the N-terminal region of xylanase A from the alkalophilic Bacillus sp. strain C-125. Images PMID:8328796

  8. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, N. S.; Joshi, V. S.; Harris, B. W.

    2009-12-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these materials. Although the two tempers show similar elongation at breakage, the ultimate tensile strength of T651 temper is generally lower than the T6 temper. Johnson-Cook strength model constants (A, B, n, C, and m) for the two alloys are determined from high strain rate tension stress-strain data at room and high temperature to 250°C. The Johnson-Cook fracture model constants are determined from quasi-static and medium strain rate as well as high temperature tests on notched and smooth tension specimens. Although the J-C strength model constants are similar, the fracture model constants show wide variations. Details of the experimental method used and the results for the two alloys are presented.

  9. An evaluation of the T-6A Texan (JPATS) functional performance of the CFIS laser assemblies

    NASA Astrophysics Data System (ADS)

    Blachowski, Thomas J.; Eccard, George

    2008-08-01

    The Indian Head Division, Naval Surface Warfare Center (IHDIV, NSWC) CAD Engineering Division is conducting a program to evaluate the laser components which comprise the Canopy Fracturing Initiation System (CFIS) currently installed on the T-6A Texan or JPATS (Joint Primary Aircraft Training System) aircraft. The T-6A Texan is the first aircraft used by the military to train future pilots. The CFIS is an element of the pilot emergency escape system which weakens the canopy in the path of the ejection seat. The CFIS is comprised of three differing configurations (Internal, External, and Seat Motion) which generate a laser pulse that is distributed through a fiber optic energy transmission system. This pulse, in turn, initiates explosive components which weaken the respective canopies. All of the CFIS laser types are flashlamp-pumped, neodymium glass lasers which are located at various positions in the aircraft cockpit area. This paper presents the CAD Engineering Division effort to evaluate the functional performance of the three CCFIS laser signal generators after their being in fleet use for a period of time.

  10. [Efficiency of Trichoderma longibrachiatum T6 in the control of Meloidogyne incognita and its rhizosphere colonization in cucumber].

    PubMed

    Zhang, Shu-wu; Xu, Bing-liang; Xue, Ying-yu; Liang, Qiao-lan; Liu, Jia

    2016-01-01

    Efficiency of different concentrations of Trichoderma longibrachiatum T6 against Meloidogyne incognita and its rhizosphere colonization in cucumber were determined in greenhouse experiments. The results of rhizosphere colonization experiments showed that the number of colonies in cucumber soil and root increased significantly ten weeks after inoculation with the second stage juveniles of M. incognita and different concentrations of T. longibrachiatum T6, and there was significant difference in different concentrations of T. longibrachiatum T6, e.g., the maximum numbers of colonies in soil and root were 7.8 x 10⁷ and 6.3 x 10⁵ CFU · mL⁻¹ respectively after treated with the spore suspension of 1.5 x 10⁷ CFU · mL⁻¹. Greenhouse experiments results showed that different concentrations of T. longibrachiatum T6 had significant control effect on different life stages of M. incognita, and the control effect increased with the concentration of T. longibrachiatum T6. T. longibrachiatum T6 significantly increased plant height, root length, above-ground and root fresh mass o cucumber inoculated by M. incognita. T. longibrachiatum T6 could colonize in cucumber rhizosphere, had control effect on M. incognita, and significantly improved the growth of cucumber. PMID:27228616

  11. Salmonella Typhimurium utilizes a T6SS-mediated antibacterial weapon to establish in the host gut

    PubMed Central

    Flaugnatti, Nicolas; Lugo, Kyler A.; Lam, Lilian H.; Jacobson, Amanda; Baylot, Virginie; Durand, Eric; Journet, Laure; Cascales, Eric; Monack, Denise M.

    2016-01-01

    The mammalian gastrointestinal tract is colonized by a high-density polymicrobial community where bacteria compete for niches and resources. One key competition strategy includes cell contact-dependent mechanisms of interbacterial antagonism, such as the type VI secretion system (T6SS), a multiprotein needle-like apparatus that injects effector proteins into prokaryotic and/or eukaryotic target cells. However, the contribution of T6SS antibacterial activity during pathogen invasion of the gut has not been demonstrated. We report that successful establishment in the gut by the enteropathogenic bacterium Salmonella enterica serovar Typhimurium requires a T6SS encoded within Salmonella pathogenicity island-6 (SPI-6). In an in vitro setting, we demonstrate that bile salts increase SPI-6 antibacterial activity and that S. Typhimurium kills commensal bacteria in a T6SS-dependent manner. Furthermore, we provide evidence that one of the two T6SS nanotube subunits, Hcp1, is required for killing Klebsiella oxytoca in vitro and that this activity is mediated by the specific interaction of Hcp1 with the antibacterial amidase Tae4. Finally, we show that K. oxytoca is killed in the host gut in an Hcp1-dependent manner and that the T6SS antibacterial activity is essential for Salmonella to establish infection within the host gut. Our findings provide an example of pathogen T6SS-dependent killing of commensal bacteria as a mechanism to successfully colonize the host gut. PMID:27503894

  12. Salmonella Typhimurium utilizes a T6SS-mediated antibacterial weapon to establish in the host gut.

    PubMed

    Sana, Thibault G; Flaugnatti, Nicolas; Lugo, Kyler A; Lam, Lilian H; Jacobson, Amanda; Baylot, Virginie; Durand, Eric; Journet, Laure; Cascales, Eric; Monack, Denise M

    2016-08-23

    The mammalian gastrointestinal tract is colonized by a high-density polymicrobial community where bacteria compete for niches and resources. One key competition strategy includes cell contact-dependent mechanisms of interbacterial antagonism, such as the type VI secretion system (T6SS), a multiprotein needle-like apparatus that injects effector proteins into prokaryotic and/or eukaryotic target cells. However, the contribution of T6SS antibacterial activity during pathogen invasion of the gut has not been demonstrated. We report that successful establishment in the gut by the enteropathogenic bacterium Salmonella enterica serovar Typhimurium requires a T6SS encoded within Salmonella pathogenicity island-6 (SPI-6). In an in vitro setting, we demonstrate that bile salts increase SPI-6 antibacterial activity and that S Typhimurium kills commensal bacteria in a T6SS-dependent manner. Furthermore, we provide evidence that one of the two T6SS nanotube subunits, Hcp1, is required for killing Klebsiella oxytoca in vitro and that this activity is mediated by the specific interaction of Hcp1 with the antibacterial amidase Tae4. Finally, we show that K. oxytoca is killed in the host gut in an Hcp1-dependent manner and that the T6SS antibacterial activity is essential for Salmonella to establish infection within the host gut. Our findings provide an example of pathogen T6SS-dependent killing of commensal bacteria as a mechanism to successfully colonize the host gut. PMID:27503894

  13. The corrosion protection of 6061-T6 aluminum by a polyurethane-sealed anodized coat

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1990-01-01

    The corrosion protection of 6061-T6 anodized aluminum afforded by a newly patented polyurethane seal was studied using the ac impedance technique. Values of the average corrosion rates over a 27-day exposure period in 3.5 percent NaCl solutions at pH 5.2 and pH 9.5 compared very favorably for Lockheed-prepared polyurethane-sealed and dichromate-sealed coats of the same thickness. Average corrosion rates for both specimens over the first 7 days of exposure compared well with those for a hard anodized, dichromate-sealed coat, but rose well above those for the hard anodized coat over the entire 27-day period. This is attributed both to the greater thickness of the hard anodized coat, and possibly to its inherently better corrosion protective capability.

  14. Built-up edge investigation in vibration drilling of Al2024-T6.

    PubMed

    Barani, A; Amini, S; Paktinat, H; Fadaei Tehrani, A

    2014-07-01

    Adding ultrasonic vibrations to drilling process results in an advanced hybrid machining process, entitled "vibration drilling". This study presents the design and fabrication of a vibration drilling tool by which both rotary and vibrating motions are applied to drill simultaneously. High frequency and low amplitude vibrations were generated by an ultrasonic transducer with frequency of 19.65 kHz. Ultrasonic transducer was controlled by a MPI ultrasonic generator with 3 kW power. The drilling tool and workpiece material were HSS two-flute twist drill and Al2024-T6, respectively. The aim of this study was investigating on the effect of ultrasonic vibrations on built-up edge, surface quality, chip morphology and wear mechanisms of drill edges. Therefore, these factors were studied in both vibration and ordinary drilling. Based on the achieved results, vibration drilling offers less built-up edge and better surface quality compared to ordinary drilling. PMID:24582556

  15. Structural analysis of Pseudomonas aeruginosa H3-T6SS immunity proteins.

    PubMed

    Yang, Xiao-Yun; Li, Zong-Qiang; She, Zhun; Geng, Zhi; Xu, Jian-Hua; Gao, Zeng-Qiang; Dong, Yu-Hui

    2016-08-01

    The Pseudomonas aeruginosa PldB protein is a transkingdom effector secreted by the Type VI Secretion System (T6SS). PA5088, PA5087, and PA5086 are three immunity proteins that can suppress the virulence of PldB. We report the crystal structures of PA5088 and PA5087 at 2.0 and 2.1 Å resolution, respectively. PA5088 and PA5087 both consist of several Sel1-like Repeats (SLRs) and form super-ring folds. Our structural analysis of these proteins revealed key differences among PA5088, PA5087, and their homologs. Our docking experiments have shed light on the putative interaction mechanism of their function as phospholipase D inhibitors. PMID:27397502

  16. Molecular cloning and expression of an isomalto-dextranase gene from Arthrobacter globiformis T6.

    PubMed Central

    Iwai, A; Ito, H; Mizuno, T; Mori, H; Matsui, H; Honma, M; Okada, G; Chiba, S

    1994-01-01

    The gene encoding an extracellular isomalto-dextranase, designated imd, was isolated from the chromosomal DNA of Arthrobacter globiformis T6 and cloned and expressed in Escherichia coli. A single open reading frame consisting of 1,926 base pairs that encoded a polypeptide composed of a signal peptide of 39 amino acids and a mature protein of 602 amino acids (M(r), 65,900) was found. The primary structure had no significant homology with the structures of any other reported carbohydrases, including two other dextranases. Transformed E. coli cells carrying the 2.3-kb fragment overproduced isomalto-dextranase into the periplasmic space under control of the promoter of the imd gene itself. Images PMID:8002600

  17. A Micro-Electrochemical Study of Friction Stir Welded Aluminum 6061-T6

    NASA Technical Reports Server (NTRS)

    Hintze, Paul E.; Calle, Luz M.

    2005-01-01

    The corrosion behavior of friction stir welded Aluminum alloy 606 1-T6 was studied using a micro-electrochemical cell. The micro-electrochemical cell has a measurement area of about 0.25 square mm which allows for measurement of corrosion properties at a very small scale. The corrosion and breakdown potentials were measured at many points inside and outside the weld along lines perpendicular to the weld. The breakdown potential is approximately equal inside and outside the weld; however, it is lower in the narrow border between the weld and base material. The results of electrochemical measurements were correlated to micro-structural analysis. The corrosion behavior of the friction stir welded samples was compared to tungsten inert gas (TIG) welded samples of the same material.

  18. Cavitation pitting and erosion of aluminum 6061-T6 in mineral oil water

    NASA Technical Reports Server (NTRS)

    Rao, B. C. S.; Buckley, D. H.

    1983-01-01

    Cavitation erosion studies of aluminum 6061-T6 in mineral oil and in ordinary tap water are presented. The maximum erosion rate (MDPR, or mean depth of penetration rate) in mineral oil was about four times that in water. The MDPR in mineral oil decreased continuously with time, but the MDPR in water remained approximately constant. The cavitation pits in mineral oil were of smaller diameter and depth than the pits in water. Treating the pits as spherical segments, we computed the radius r of the sphere. The logarithm of h/a, where h is the pit depth and 2a is the top width of the pit, was linear when plotted against the logarithm of 2r/h - 1.

  19. Statistical analysis of constituent particles in 7075-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Harlow, D. G.; Wei, R. P.; Wang, M. Z.

    2006-11-01

    Pitting corrosion is a primary degradation mechanism that affects the durability and integrity of aluminum alloy structures especially in aircraft. The heterogeneity of aluminum alloys is directly responsible for pitting corrosion because about 200 constituent particles per mm2 are on polished surfaces. Corrosion pits commence at surface particles and evolve into severe pits by sustained growth through particle clusters. Severe pits are nuclei for subsequent corrosion fatigue cracking. Thus, heterogeneous clusters of constituent particles are critical to the quality of aluminum alloys subjected to deleterious environments. Models for structural reliability including corrosion fundamentally depend on quantitative descriptions of the spatial statistics of the particles and particle clusters, including their location, size, and density. The primary purpose of this effort is to statistically estimate the distribution functions of the key geometrical properties of the constituent particles in 7075-T6 aluminum alloy and their role in pitting corrosion.

  20. Effects of select parameters on electron beam welding of AL6061-T6 alloy

    NASA Astrophysics Data System (ADS)

    Yost, Thomas E.

    Electron beam welding was used for joining Al6061-T6, precision machined, cylindrical sections. The welded assembly exhibited a minimum amount of distortion, but a better understanding of the effects of several key welding parameters on the structural integrity of the weld was required. The contents of this document describe the relative importance and interaction between welding speed, volume of filler, and beam pattern on the microstructural and mechanical properties of the welded joint. Understanding of the relationship between welding parameters and weld properties was accomplished by macrophotography and microstructural examination, microhardness testing, energy dispersive spectroscopy (EDX), and mechanical tensile testing of weld coupons. The results of this study will help quantify the robustness of the EBW process for this common aerospace material and joint geometry and will help determine the impacts of process deviations on weld fidelity in the production environment.

  1. Overexpression of a Homeobox Gene, LeT6, Reveals Indeterminate Features in the Tomato Compound Leaf1

    PubMed Central

    Janssen, Bart-Jan; Lund, Lance; Sinha, Neelima

    1998-01-01

    The cultivated tomato (Lycopersicon esculentum) has a unipinnate compound leaf. In the developing leaf primordium, major leaflet initiation is basipetal, and lobe formation and early vascular differentiation are acropetal. We show that engineered alterations in the expression of a tomato homeobox gene, LeT6, can cause dramatic changes in leaf morphology. The morphological states are variable and unstable and the phenotypes produced indicate that the tomato leaf has an inherent level of indeterminacy. This is manifested by the production of multiple orders of compounding in the leaf, by numerous shoot, inflorescence, and floral meristems on leaves, and by the conversion of rachis-petiolule junctions into “axillary” positions where floral buds can arise. Overexpression of a heterologous homeobox transgene, kn1, does not produce such phenotypic variability. This indicates that LeT6 may differ from the heterologous kn1 gene in the effects manifested on overexpression, and that 35S-LeT6 plants may be subject to alterations in expression of both the introduced and endogenous LeT6 genes. The expression patterns of LeT6 argue in favor of a fundamental role for LeT6 in morphogenesis of leaves in tomato and also suggest that variability in homeobox gene expression may account for some of the diversity in leaf form seen in nature. PMID:9662520

  2. Low-temperature densification of ultrafine grained aluminum 6061-T6 by polymer bonding

    NASA Astrophysics Data System (ADS)

    Kim, Boumseock

    Ultrafine grained and nanocrytalline materials have many beneficial properties such as higher hardness, strength and wear resistance. A machining process has been developed as a new method to make nanostructured metals or alloys. Through the process, severe plastic deformation can be applied to metals or alloys and they become ultrafine grain and nanocrystalline in their structures. Because ultrafine grained alloys made by machining are made up to small chips, not bulk, to make bulk material, the alloy chips must be densified through processes such as sintering. Unfortunately, during the conventional sintering, the ultrafine grained alloys show grain growth at high rate and lose their hardness and strength. Therefore, low-temperature densification of ultrafine grained alloys has been pursued. In this thesis, ultrafine-grained (UFG) Al 6061-T6 particulate produced from machining chips have been consolidated and bonded using liquid epoxies that cure at 100?, below the coarsening temperature of the UFG structure. Two routes were explored---die-pressing premixed alloy particulate and epoxy and pressure infiltration of pre-pressed alloy particulate preforms. The effects of pressing pressure and epoxy viscosity were investigated. In order to reduce porosity and contamination, three treatments---application of pressure during curing of epoxy, the cleaning of the alloy powder with NaOH solution and degassing epoxy before pressing---were tried. In order to overcome limitation of diepressing, infiltration method was compared with die-pressing and the resulting properties of the composite discussed. Bond thickness between the alloy particles increases with the viscosity of the epoxies. In the hardness results by micro-indentor, the value of composite with more than 80% volume fraction of Al alloy chip (Va) was more than 120 kg/mm2. In those measurements, the hardness of the composite depends mainly on the volume fraction of Al alloy and was clearly influenced by the boundary

  3. The glucuronic acid utilization gene cluster from Bacillus stearothermophilus T-6.

    PubMed

    Shulami, S; Gat, O; Sonenshein, A L; Shoham, Y

    1999-06-01

    A lambda-EMBL3 genomic library of Bacillus stearothermophilus T-6 was screened for hemicellulolytic activities, and five independent clones exhibiting beta-xylosidase activity were isolated. The clones overlap each other and together represent a 23.5-kb chromosomal segment. The segment contains a cluster of xylan utilization genes, which are organized in at least three transcriptional units. These include the gene for the extracellular xylanase, xylanase T-6; part of an operon coding for an intracellular xylanase and a beta-xylosidase; and a putative 15.5-kb-long transcriptional unit, consisting of 12 genes involved in the utilization of alpha-D-glucuronic acid (GlcUA). The first four genes in the potential GlcUA operon (orf1, -2, -3, and -4) code for a putative sugar transport system with characteristic components of the binding-protein-dependent transport systems. The most likely natural substrate for this transport system is aldotetraouronic acid [2-O-alpha-(4-O-methyl-alpha-D-glucuronosyl)-xylotriose] (MeGlcUAXyl3). The following two genes code for an intracellular alpha-glucuronidase (aguA) and a beta-xylosidase (xynB). Five more genes (kdgK, kdgA, uxaC, uxuA, and uxuB) encode proteins that are homologous to enzymes involved in galacturonate and glucuronate catabolism. The gene cluster also includes a potential regulatory gene, uxuR, the product of which resembles repressors of the GntR family. The apparent transcriptional start point of the cluster was determined by primer extension analysis and is located 349 bp from the initial ATG codon. The potential operator site is a perfect 12-bp inverted repeat located downstream from the promoter between nucleotides +170 and +181. Gel retardation assays indicated that UxuR binds specifically to this sequence and that this binding is efficiently prevented in vitro by MeGlcUAXyl3, the most likely molecular inducer. PMID:10368143

  4. Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

    NASA Astrophysics Data System (ADS)

    Florea, Radu Stefanel

    This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

  5. Erosion of aluminum 6061-T6 under cavitation attack in mineral oil and water

    NASA Technical Reports Server (NTRS)

    Rao, B. C. S.; Buckley, D. H.

    1985-01-01

    Studies of the erosion of aluminum 6061-T6 under cavitation attack in distilled water, ordinary tap water and a viscous mineral oil are presented. The mean depth of penetration for the mineral oil was about 40 percent of that for water at the end of a 40 min test. The mean depth of penetration and its rate did not differ significantly for distilled and tap water. The mean depth of penetration rate for both distilled and tap water increased to a maximum and then decreased with test duration, while that for mineral oil had a maximum during the initial period. The ratio h/2a of the pit depth h to the pit diameter 2a varied from 0.04 to 0.13 in water and from 0.06 to 0.20 in mineral oil. Scanning electron microscopy indicates that the pits are initially formed over the grain boundaries and precipitates while the surface grains are deformed under cavitation attack.

  6. Effect of Laser Shock Peening on surface properties and residual stress of Al6061-T6

    NASA Astrophysics Data System (ADS)

    Salimianrizi, A.; Foroozmehr, E.; Badrossamay, M.; Farrokhpour, H.

    2016-02-01

    The purpose of this study is to investigate the effects of Laser Shock Peening (LSP) on Al 6061-T6. The confined LSP regime using Nd: YAG laser with 1200 mJ of energy per pulse and 8 ns of pulse width were applied. The treated specimens were evaluated by means of surface integrity with optical microscopy, scanning electron microscope, microhardness, surface roughness and induced residual stress using an X-ray diffraction method. Results showed that by the use of LSP, compressive residual stress could effectively be induced on the surface of treated material. It was also revealed that the hardened depth of the material, up to a maximum depth of 1875 μm, could be achieved due to work hardening and grain refinement. In addition, surface roughness measurements showed that the LSP could deteriorate surface quality depending on the LSP parameters. The influences of beam overlap rates, number of laser shots and scanning pattern on microhardness as well as surface roughness are discussed.

  7. Microstructure and Mechanical Behavior of Al 7075-T6 Subjected to Shallow Cryogenic Treatment

    NASA Astrophysics Data System (ADS)

    Mohan, K.; Suresh, J. A.; Ramu, Palaniappan; Jayaganthan, R.

    2016-04-01

    The effect of shallow cryogenic treatment (SCT) on the microstructure and mechanical properties of Al7075-T6 is investigated in the present work. The alloy was subjected to shallow CT at -80 °C for 72 h. Mechanical tests such as Vickers hardness test, tensile, and fatigue tests were performed on both native and treated samples. It was observed that the mechanical properties such as hardness, yield strength, and ultimate tensile strength increased by about 30, 17, and 7%, respectively, for the treated sample. The treated alloy was characterized by using the techniques such as optical microscopy, electron back scattered diffraction (EBSD), energy-dispersive x-ray spectroscopy (EDS), and transmission electron microscopy (TEM) to observe the changes in the microstructural features. EBSD results show precipitation, better distribution of second-phase particles, and higher dislocation density in the treated alloy as compared to the untreated alloy. The treatment imparts improved hardness and strength to the alloy due to precipitation hardening and high dislocation density. Fracture morphologies of the treated and the native samples were characterized by using scanning electron microscopy and it was observed that the striations were denser in the treated sample justifying the higher fatigue strength.

  8. Microstructure and Mechanical Behavior of Al 7075-T6 Subjected to Shallow Cryogenic Treatment

    NASA Astrophysics Data System (ADS)

    Mohan, K.; Suresh, J. A.; Ramu, Palaniappan; Jayaganthan, R.

    2016-06-01

    The effect of shallow cryogenic treatment (SCT) on the microstructure and mechanical properties of Al7075-T6 is investigated in the present work. The alloy was subjected to shallow CT at -80 °C for 72 h. Mechanical tests such as Vickers hardness test, tensile, and fatigue tests were performed on both native and treated samples. It was observed that the mechanical properties such as hardness, yield strength, and ultimate tensile strength increased by about 30, 17, and 7%, respectively, for the treated sample. The treated alloy was characterized by using the techniques such as optical microscopy, electron back scattered diffraction (EBSD), energy-dispersive x-ray spectroscopy (EDS), and transmission electron microscopy (TEM) to observe the changes in the microstructural features. EBSD results show precipitation, better distribution of second-phase particles, and higher dislocation density in the treated alloy as compared to the untreated alloy. The treatment imparts improved hardness and strength to the alloy due to precipitation hardening and high dislocation density. Fracture morphologies of the treated and the native samples were characterized by using scanning electron microscopy and it was observed that the striations were denser in the treated sample justifying the higher fatigue strength.

  9. Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

    DOE PAGESBeta

    Squires, Lile; Lim, Yong Chae; Miles, Michael; Feng, Zhili

    2015-03-18

    In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its highermore » alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.« less

  10. CO2 laser beam welding of 6061-T6 aluminum alloy thin plate

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.; Todaka, Hirotaka

    1997-12-01

    Laser beam welding is an attractive welding process for age-hardened aluminum alloys, because its low heat input minimizes the width of weld fusion and heat-affected zones (HAZs). In the present work, 1-mm-thick age-hardened Al-Mg-Si alloy, 6061-T6, plates were welded with full penetration using a 2.5-kW CO2 laser. Fractions of porosity in the fusion zones were less than 0.05 pct in bead-on-plate welding and less than 0.2 pct in butt welding with polishing the groove surface before welding. The width of a softened region in the-laser beam welds was less than 1/4 times that of a tungsten inert gas (TIG) weld. The softened region is caused by reversion of strengthening β″ (Mg2Si) precipitates due to weld heat input. The hardness values of the softened region in the laser beam welds were almost fully recovered to that of the base metal after an artificial aging treatment at 448 K for 28.8 ks without solution annealing, whereas those in the TIG weld were not recovered in a partly reverted region. Both the bead-on-plate weld and the butt weld after the postweld artificial aging treatment had almost equivalent tensile strengths to that of the base plate.

  11. Characteristics of laser beam welds of age-hardenable 6061-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.

    2003-03-01

    Laser beam welding is attractive for joining age-hardenable aluminum alloys, because its low over-all heat input results in a narrow weld heat affected zone (HAZ), where softening caused by dissolution of age precipitates occurs. In the present work, 1mm-thick 6061-T6 aluminum alloy plates were welded using a 2.5 kW CO2 laser and it was experimentally proved that the width of the softened region in the laser beam weld was less than 1/7 that of a TIG weld. Moreover the hardness in the softened region of the laser beam weld was found to be almost fully recovered to the base metal hardness by applying a post-weld aging treatment at 443 K for 28.8 ks without solution annealing unlike the TIG weld. These results characterize the advantage of laser beam welding in joining of the age-hardenable aluminum alloy as compared with the conventional arc welding. The hardness distributions in the HAZ were theoretically evaluated based on kinetic equations describing the dissolution of hardening β' (Mg2Si) precipitates and the precipitation of non-hardening β' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  12. The effects of pitting on fatigue crack nucleation in 7075-T6 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Ma, LI; Hoeppner, David W.

    1994-01-01

    A high-strength aluminum alloy, 7075-T6, was studied to quantitatively evaluate chemical pitting effects of its corrosion fatigue life. The study focused on pit nucleation, pit growth, and fatigue crack nucleation. Pitting corrosion fatigue experiments were conducted in 3.5 percent NaCl aqueous solution under constant amplitude sinusoidal loading at two frequencies, 5 and 20 Hz. Smooth and unnotched specimens were used in this investigation. A video recording system was developed to allow in situ observation of the surface changes of the specimens during testing. The results indicated that pitting corrosion considerably reduces the fatigue strength by accelerating fatigue crack nucleation. A metallographic examination was conducted on the specimens to evaluate the nature of corrosion pits. First, the actual shapes of the corrosion pits were evaluated by cross-sectioning the pits. Secondly, the relation between corrosion pits and microstructure was also investigated. Finally, the possibility of another corrosion mechanism that might be involved in pitting was explored in this investigation. The fractography of the tested specimens showed that corner corrosion pits were responsible for fatigue crack nucleation in the material due to the associated stress concentration. The pits exhibited variance of morphology. Fatigue life for the experimental conditions appeared to be strongly dependent on pitting kinetics and the crack nucleation stage.

  13. Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

    SciTech Connect

    Squires, Lile; Lim, Yong Chae; Miles, Michael; Feng, Zhili

    2015-03-18

    In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its higher alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.

  14. Saikosaponin a and saikosaponin d inhibit proliferation and migratory activity of rat HSC-T6 cells.

    PubMed

    Chen, Ming Feng; Huang, Chao Cheng; Liu, Pei Shan; Chen, Chang Han; Shiu, Li Yen

    2013-09-01

    The proliferation and migration of hepatic stellate cells (HSCs) profoundly impact the pathogenesis of liver inflammation and fibrogenesis. As a perennial herb native to China, Bupleurum falcatum is administered for its anti-inflammatory, antipyretic, and antihepatotoxic effects. Saikosaponin a (SSa) and Saikosaponin d (SSd) are the major active components of triterpene saponins in Bupleurum falcatum. This study analyzes how SSa and SSd affect rat HSC-T6 cell line proliferation and migration. Experimental results indicate that, in addition to suppressing HSC-T6 proliferation, wound healing activity and cell migration in a time- and dose-dependent manner, SSa and SSd significantly induce apoptosis. Additionally, SSa and SSd decreased the expressions of extracellular matrix-regulated kinase 1/2 (ERK1/2), platelet-derived growth factor receptor 1 (PDGFR1), and subsequently transforming growth factor-β1 receptor (TGF-β1R), α-smooth muscle actin, TGF-β1 and connective tissue growth factor. They also decreased phosphorylation of p38 (p-p38) and ERK1/2 (p-ERK1/2) of HSC-T6. Furthermore, both SSa and SSd can block PDGF-BB and TGF-β1-induced cell proliferation and migration of HSC-T6. These results suggest that SSa and SSd may inhibit proliferation and activation of HSC-T6, and the modulated mechanisms warrant further study. PMID:24044489

  15. Ratcheting fatigue behaviour of Al-7075 T6 alloy: Influence of stress parameters

    NASA Astrophysics Data System (ADS)

    Amarnath, Lala; Bhattacharjee, Antara; Dutta, K.

    2016-02-01

    The use of aluminium and aluminium based alloys are increasing rapidly on account of its high formability, good thermal and electrical conductivity, high strength and lightness. Aluminium alloys are extensively used in aerospace, automobile, marine and space research industries and are also put into structural applications where chances of fatigue damage cannot be ruled out. In the current work, it is intended to study the ratcheting fatigue behavior of 7075-T6 aluminium alloy at room temperature. This Al alloy is potentially used in aviation, marine and automotive components as well as in bicycle parts, rock mounting equipment and parts of ammunition where there is every chance of failure of the parts due to deformation caused by ratcheting. Ratcheting is the process of accruement of plastic stain produced when a component is subjected to asymmetric cyclic loading under the influence of low cycle fatigue. To accomplish the requirements of the projected research, stress-controlled cyclic loading experiments were done using a ±250 kN servo-hydraulic universal testing machine (Instron: 8800R). The effect of stress parameters such as mean stress and stress amplitude were investigated on the ratcheting behavior of the selected aluminium alloy. It was observed that, ratcheting strain increased with increase in the value of stress amplitude at any constant mean stress while a saturation in strain accumulation attained in the investigated material after around 10-20 cycles, under all test conditions. The analyses of hysteresis loop generated during cyclic loading indicate that the material exhibits cyclic hardening in the initial fifty cycles which gets softened in further loading up to about 70-80 cycles and finally attains a steady state. The increase in the ratcheting strain value with stress parameters happens owing to increased deformation domain during cycling. The cyclic hardening accompanied by softening is correlated with characteristic precipitation features of

  16. The structure of T6 human insulin at 1.0 A resolution.

    PubMed

    Smith, G David; Pangborn, Walter A; Blessing, Robert H

    2003-03-01

    The structure of T(6) human insulin has been determined at 120 K at a resolution of 1.0 A and refined to a residual of 0.183. As a result of cryofreezing, the first four residues of the B chain in one of the two crystallographically independent AB monomers in the hexameric [Zn(1/3)(AB)(2)Zn(1/3)](3) complex undergo a conformational shift that displaces the C(alpha) atom of PheB1 by 7.86 A relative to the room-temperature structure. A least-squares superposition of all backbone atoms of the room-temperature and low-temperature structures yielded a mean displacement of 0.422 A. Omitting the first four residues of the B chain reduced the mean displacement to 0.272 A. At 120 K, nine residues were found to exhibit two discrete side-chain conformations, but only two of these residues are in common with the seven residues found to have disordered side chains in the room-temperature structure. As a result of freezing, the disorder observed at room temperature in both ArgB22 side chains is eliminated. The close contact between pairs of O( epsilon 2) atoms in GluB13 observed at room temperature is maintained at cryotemperature and suggests that a carboxylate-carboxylic acid centered hydrogen bond exists [-C(=O)-O.H.O-C(=O)-] such that the H atom is equally shared between the two partially charged O atoms. PMID:12595704

  17. Recovery of Mechanical Properties of a 6061-T6 Aluminum Weld by Heat Treatment After Welding

    NASA Astrophysics Data System (ADS)

    Pérez, Javier Serrano; Ambriz, Ricardo Rafael; López, Francisco Fernando Curiel; Vigueras, David Jaramillo

    2016-07-01

    The dilution effects in welds of a 6061-T6 (Al-Si-Mg) alloy obtained by the modified indirect electric arc (MIEA), using an ER4043 filler metal (Al-Si), and postweld heat treatment (PWHT) were analyzed. The soft zone (55 to 70 HV0.1) formed by the microstructural transformation in the heat-affected zone (HAZ) was eliminated. The hardness measurements were presented on a traditional microhardness profile and mapping representation. A hardening effect of the fusion zone was observed; the hardness values were above 120 HV0.1 and tended to be uniform. This behavior could be attributed to the chemical composition of the filler metal, the Mg migration from the base to the weld metal, and the reversible process of the PWHT, which promotes precipitation hardening. Improvement for yield (260 MPa) and tensile strength (310 MPa) of the MIEA joints was observed; these values were similar to those obtained for the base metal. However, the presence of porosity in the fusion zone limits the ductility of the joints (4.3 pct). Even though the yield and tensile strengths of the base metal and welded joints were similar, the stress concentration due to porosity in the weld metal generated data dispersion in fatigue life. As a consequence, the high-cycle fatigue life decreases with respect to the base metal. In contrast, when the crack propagates under elastic conditions, the crack-tip singularity is affected by the porosity in the weld metal (stress liberator). This aspect, in conjunction with the hardening effect in joints subjected to PWHT, improves the fatigue crack growth rate when compared to the as-welded condition.

  18. Multistage Fatigue Modeling of Cast A356-T6 and A380-F Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Xue, Y.; Burton, C. L.; Horstemeyer, M. F.; McDowell, D. L.; Berry, J. T.

    2007-08-01

    This article presents a microstructure-based multistage fatigue (MSF) model extended from the model developed by McDowell et al.[1,2] to an A380-F aluminum alloy to consider microstructure-property relations of descending order, signifying deleterious effects of defects/discontinuities: (1) pores or oxides greater than 100 μm, (2) pores or oxides greater than 50 μm near the free surface, (3) a high porosity region with an area greater than 200 μm, and (4) oxide film of an area greater than 10,000 μm2. These microconstituents, inclusions, or discontinuities represent different casting features that may dominate fatigue life at stages of fatigue damage evolutions. The incubation life is estimated using a modified Coffin Mansion law at the microscale based on the microplasticity at the discontinuity. The microstructurally small crack (MSC) and physically small crack (PSC) growth was modeled using the crack tip displacement as the driving force, which is affected by the porosity and dendrite cell size (DCS). When the fatigue damage evolves to several DCSs, cracks behave as long cracks with growth subject to the effective stress intensity factor in linear elastic fracture mechanics. Based on an understanding of the microstructures of A380-F and A356-T6 aluminum alloys, an engineering treatment of the MSF model was introduced for A380-F aluminum alloys by tailoring a few model parameters based on the mechanical properties of the alloy. The MSF model is used to predict the upper and lower bounds of the experimental fatigue strain life and stress life of the two cast aluminum alloys.

  19. Identification of modes of fracture in a 2618-T6 aluminum alloy using stereophotogrammetry

    SciTech Connect

    Salas Zamarripa, A.; Mata, M.P. Guerrero; Morales, M. Castillo; Beber-Solano, T.P.

    2011-12-15

    The identification and the development of a quantification technique of the modes of fracture in fatigue fracture surfaces of a 2618-T6 aluminum alloy were developed during this research. Fatigue tests at room and high temperature (230 Degree-Sign C) were carried out to be able to compare the microscopic fractographic features developed by this material under these testing conditions. The overall observations by scanning electron microscopy (SEM) of the fracture surfaces showed a mixture of transgranular and ductile intergranular fracture. The ductile intergranular fracture contribution appears to be more significant at room temperature than at 230 Degree-Sign C. A quantitative methodology was developed to identify and to measure the contribution of these microscopic fractographic features. The technique consisted of a combination of stereophotogrammetry and image analysis. Stereo-pairs were randomly taken along the crack paths and were then analyzed using the profile module of MeX software. The analysis involved the 3-D surface reconstruction, the trace of primary profile lines in both vertical and horizontal directions within the stereo-pair area, the measurements of the contribution of the modes of fracture in each profile, and finally, the calculation of the average contribution in each stereo-pair. The technique results confirmed a higher contribution of ductile intergranular fracture at room temperature than at 230 Degree-Sign C. Moreover, there was no indication of a direct relationship between this contribution and the strain amplitudes range applied during the fatigue testing. - Highlights: Black-Right-Pointing-Pointer Stereophotogrammetry and image analysis as a measuring tool of modes of fracture in fatigue fracture surfaces. Black-Right-Pointing-Pointer A mixture of ductile intergranular and transgranular fracture was identified at room temperature and 230 Degree-Sign C testing. Black-Right-Pointing-Pointer Development of a quantitative methodology to

  20. Structural insights into methanol-stable variants of lipase T6 from Geobacillus stearothermophilus.

    PubMed

    Dror, Adi; Kanteev, Margarita; Kagan, Irit; Gihaz, Shalev; Shahar, Anat; Fishman, Ayelet

    2015-11-01

    Enzymatic production of biodiesel by transesterification of triglycerides and alcohol, catalyzed by lipases, offers an environmentally friendly and efficient alternative to the chemically catalyzed process while using low-grade feedstocks. Methanol is utilized frequently as the alcohol in the reaction due to its reactivity and low cost. However, one of the major drawbacks of the enzymatic system is the presence of high methanol concentrations which leads to methanol-induced unfolding and inactivation of the biocatalyst. Therefore, a methanol-stable lipase is of great interest for the biodiesel industry. In this study, protein engineering was applied to substitute charged surface residues with hydrophobic ones to enhance the stability in methanol of a lipase from Geobacillus stearothermophilus T6. We identified a methanol-stable variant, R374W, and combined it with a variant found previously, H86Y/A269T. The triple mutant, H86Y/A269T/R374W, had a half-life value at 70 % methanol of 324 min which reflects an 87-fold enhanced stability compared to the wild type together with elevated thermostability in buffer and in 50 % methanol. This variant also exhibited an improved biodiesel yield from waste chicken oil compared to commercial Lipolase 100L® and Novozyme® CALB. Crystal structures of the wild type and the methanol-stable variants provided insights regarding structure-stability correlations. The most prominent features were the extensive formation of new hydrogen bonds between surface residues directly or mediated by structural water molecules and the stabilization of Zn and Ca binding sites. Mutation sites were also characterized by lower B-factor values calculated from the X-ray structures indicating improved rigidity. PMID:26026940

  1. Involvement of T6 Pili in Biofilm Formation by Serotype M6 Streptococcus pyogenes

    PubMed Central

    Kimura, Keiji Richard; Nakata, Masanobu; Sumitomo, Tomoko; Kreikemeyer, Bernd; Podbielski, Andreas; Terao, Yutaka

    2012-01-01

    The group A streptococcus (GAS) Streptococcus pyogenes is known to cause self-limiting purulent infections in humans. The role of GAS pili in host cell adhesion and biofilm formation is likely fundamental in early colonization. Pilus genes are found in the FCT (fibronectin-binding protein, collagen-binding protein, and trypsin-resistant antigen) genomic region, which has been classified into nine subtypes based on the diversity of gene content and nucleotide sequence. Several epidemiological studies have indicated that FCT type 1 strains, including serotype M6, produce large amounts of monospecies biofilm in vitro. We examined the direct involvement of pili in biofilm formation by serotype M6 clinical isolates. In the majority of tested strains, deletion of the tee6 gene encoding pilus shaft protein T6 compromised the ability to form biofilm on an abiotic surface. Deletion of the fctX and srtB genes, which encode pilus ancillary protein and class C pilus-associated sortase, respectively, also decreased biofilm formation by a representative strain. Unexpectedly, these mutant strains showed increased bacterial aggregation compared with that of the wild-type strain. When the entire FCT type 1 pilus region was ectopically expressed in serotype M1 strain SF370, biofilm formation was promoted and autoaggregation was inhibited. These findings indicate that assembled FCT type 1 pili contribute to biofilm formation and also function as attenuators of bacterial aggregation. Taken together, our results show the potential role of FCT type 1 pili in the pathogenesis of GAS infections. PMID:22155780

  2. Recovery of Mechanical Properties of a 6061-T6 Aluminum Weld by Heat Treatment After Welding

    NASA Astrophysics Data System (ADS)

    Pérez, Javier Serrano; Ambriz, Ricardo Rafael; López, Francisco Fernando Curiel; Vigueras, David Jaramillo

    2016-05-01

    The dilution effects in welds of a 6061-T6 (Al-Si-Mg) alloy obtained by the modified indirect electric arc (MIEA), using an ER4043 filler metal (Al-Si), and postweld heat treatment (PWHT) were analyzed. The soft zone (55 to 70 HV0.1) formed by the microstructural transformation in the heat-affected zone (HAZ) was eliminated. The hardness measurements were presented on a traditional microhardness profile and mapping representation. A hardening effect of the fusion zone was observed; the hardness values were above 120 HV0.1 and tended to be uniform. This behavior could be attributed to the chemical composition of the filler metal, the Mg migration from the base to the weld metal, and the reversible process of the PWHT, which promotes precipitation hardening. Improvement for yield (260 MPa) and tensile strength (310 MPa) of the MIEA joints was observed; these values were similar to those obtained for the base metal. However, the presence of porosity in the fusion zone limits the ductility of the joints (4.3 pct). Even though the yield and tensile strengths of the base metal and welded joints were similar, the stress concentration due to porosity in the weld metal generated data dispersion in fatigue life. As a consequence, the high-cycle fatigue life decreases with respect to the base metal. In contrast, when the crack propagates under elastic conditions, the crack-tip singularity is affected by the porosity in the weld metal (stress liberator). This aspect, in conjunction with the hardening effect in joints subjected to PWHT, improves the fatigue crack growth rate when compared to the as-welded condition.

  3. Diversity of the biosynthesis pathway for threonylcarbamoyladenosine (t6A), a universal modification of tRNA

    PubMed Central

    Thiaville, Patrick C; Iwata-Reuyl, Dirk; de Crécy-Lagard, Valérie

    2014-01-01

    The tRNA modification field has a rich literature covering biochemical analysis going back more than 40 years, but many of the corresponding genes were only identified in the last decade. In recent years, comparative genomic-driven analysis has allowed for the identification of the genes and subsequent characterization of the enzymes responsible for N6-threonylcarbamoyladenosine (t6A). This universal modification, located in the anticodon stem-loop at position 37 adjacent to the anticodon of tRNAs, is found in nearly all tRNAs that decode ANN codons. The t6A biosynthesis enzymes and synthesis pathways have now been identified, revealing both a core set of enzymes and kingdom-specific variations. This review focuses on the elucidation of the pathway, diversity of the synthesis genes, and proposes a new nomenclature for t6A synthesis enzymes. PMID:25629598

  4. Investigating the presence of predatory bacteria on algal bloom samples using a T6SS gene marker.

    NASA Astrophysics Data System (ADS)

    Hendricks, J.; Sison-Mangus, M.; Mehic, S.; McMahon, E.

    2015-12-01

    Predation is considered to be a major driving force in evolution and ecology, which has been observed affecting individual organisms, communities, and entire ecosystems. The type VI secretion system (T6SS) is an intermembranal protein complex identified in certain bacteria, which appears to have evolved strictly as a mechanism of predation. The effects of bacteria on phytoplankton physiology are still understudied, however, studies have shown that the interactions between bacteria that inhabit the phycosphere of phytoplankton can possibly result in coevolution of native host and microbiota. It is unclear if bacteria can prey upon other bacteria to gain advantages during periods of high phytoplankton density. Here, we investigate the predatory interactions between bacteria and analyze environmental samples for the presence of predatory bacterial genes in an effort to understand bacteria-bacteria and phytoplankton interactions during algal blooms. DNA were extracted from bacterial samples collected weekly from size-fractionated samples using 3.0 um and 0.2 um membrane filters at the Santa Cruz wharf. PCR amplification and gel visualization for the presence of T6SS gene was carried out on bloom and non-bloom samples. Moreover, we carried out a lab- based experiment to observe bacteria-bacteria interaction that may hint for the presence of predatory behavior between bacterial taxa. We observed what appeared to be a predatory biofilm formation between certain bacterial species. These bacteria, however, did not contain the T6SS genes. On the contrary the T6SS gene was discovered in some of the bloom samples gathered from the Santa Cruz wharf. It is still unclear if the predatory mechanisms facilitate the abundance of certain groups of bacteria that contain the T6SS genes during algal blooms, but our evidence suggest that bacterial predation through T6SS mechanism is present during bloom events.

  5. Draft Genome Sequence of Geobacillus sp. Isolate T6, a Thermophilic Bacterium Collected from a Thermal Spring in Argentina

    PubMed Central

    Ortiz, Elio M.; Berretta, Marcelo F.; Benintende, Graciela B.; Amadio, Ariel F.; Zandomeni, Rubén O.

    2015-01-01

    Geobacillus sp. isolate T6 was collected from a thermal spring in Salta, Argentina. The draft genome sequence (3,767,773 bp) of this isolate is represented by one major scaffold of 3,46 Mbp, a second one of 207 kbp, and 20 scaffolds of <13 kbp. The assembled sequences revealed 3,919 protein-coding genes. PMID:26184933

  6. Estudio numerico y experimental del proceso de soldeo MIG sobre la aleacion 6063--T5 utilizando el metodo de Taguchi

    NASA Astrophysics Data System (ADS)

    Meseguer Valdenebro, Jose Luis

    improvement on mechanical properties in aluminum metal joint. Los procesos de soldadura por arco electrico representan unas de las tecnicas mas utilizadas en los procesos de fabricacion de componentes mecanicos en la industria moderna. Los procesos de soldeo por arco se han adaptado a las necesidades actuales, haciendose un modo de fabricacion flexible y versatil. Los resultados obtenidos numericamente en el proceso de soldadura son validados experimentalmente. Los principales metodos numericos mas empleados en la actualidad son tres, metodo por diferencias finitas, metodos por elementos finitos y metodo por volumenes finitos. El metodo numerico mas empleado para el modelado de uniones soldadas, es el metodo por elementos finitos, debido a que presenta una buena adaptacion a las condiciones geometricas y de contorno ademas de que existe una diversidad de programas comerciales que utilizan el metodo por elementos finitos como base de calculo. Este trabajo de investigacion presenta un estudio experimental de una union soldada mediante el proceso MIG de la aleacion de aluminio 6063-T5. El metodo numerico se valida experimentalmente aplicando el metodo de los elementos finitos con el programa de calculo ANSYS. Los resultados experimentales obtenidos son: las curvas de enfriamiento, el tiempo critico de enfriamiento t4/3, geometria del cordon, microdurezas obtenidas en la union soldada, zona afectada termicamente y metal base, dilucion del proceso, areas criticas intersecadas entre las curvas de enfriamiento y la curva TTP. Los resultados numericos son: las curvas del ciclo termico, que representan tanto el calentamiento hasta alcanzar la temperatura maxima y un posterior enfriamiento. Se calculan el tiempo critico de enfriamiento t4/3, el rendimiento termico y se representa la geometria del cordon obtenida experimentalmente. La zona afectada termicamente se obtiene diferenciando las zonas que se encuentran a diferentes temperaturas, las areas criticas intersecadas entre las

  7. Structural-phase changes in Al6061-T6 alloy during high-dose N-2(+) implantation

    NASA Astrophysics Data System (ADS)

    Soukieh, M.

    2004-02-01

    N 2 + nitrogen ions with an energy of 50 keV were implanted into Al6061-T6 alloy with high dose (10(16) - 2 x 10(17) ions/cm(2)) at room temperature in order to form thin aluminium nitride (AlN) layers. The structural-phase changes in implanted Al 6061-T6 alloy were investigated using Rutherford back-scattering and transmission electron microscopic techniques. The results indicate that nitrogen implantation led to the formation of nitride phases (AlN, Al7N C-3(3)) which improved the surface hardness by 80% and increased the electrical resistance up to 1800% at maximum dose (2 x 10(17) ions/cm(2)).

  8. Evaluation of Dissimilar Welds of 5083-H12 and 6061-T6 Produced by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Ghaffarpour, Morteza; Kolahgar, Sina; Dariani, Bijan Mollaei; Dehghani, Kamran

    2013-08-01

    In the present study, the dissimilar aluminum alloys of 5083-H12 and 6061-T6 were joined by friction stir welding (FSW). Then, the design of experiments (DOE), the Box-Benken method, and the response surface methodology (RSM) were used to optimize the effective parameters of the FSW process. The optimized parameters that led to the maximum tensile strength in dissimilar friction stir welded sheets were determined. The predicted results were then compared with those measured experimentally. The results show that there is good agreement between the predicted and measured amounts. By applying the limit dome height (LDH) test, the formability of friction stir welded sheets was studied. During the LDH test, the minimum formability occurred in the heat-affected zone (HAZ) of the 6061-T6 side. The results of microhardness and tensile tests confirm the results of the LDH tests.

  9. Over-aging of aluminum alloys. Final report. [7050-T736; 7075-T6; 9021-T4; 9052-F

    SciTech Connect

    Ulitchny, M.G.

    1983-12-01

    The effects of short-time over-aging on the mechanical properties of aluminum alloys 7050-T736, 7075-T6, 9021-T4, and 9052-F have been evaluated. Test results show that when subjected to a temperature of 600/sup 0/F for short periods of time, the 7XXX series alloys lose almost all of the tensile strength they received through heat treatment; alloy 9021-T4 loses less of its strength; and 9052-F loses almost none of its strength. Tensile tests carried out on 7050-T736 and 7075-T6 in both the as-received and stress-relief-annealed conditions have confirmed that the stress relief anneal has little or no effect on tensile strength.

  10. Determination of the dynamic stress intensity factors for 7075-T6 aluminum alloy using the reflected caustic method

    SciTech Connect

    Tsukagoshi, Seiji; Takahashi, Susumu; Shimamoto, Akira

    1996-12-31

    Dynamic fracture initiation and propagation in Al 7075-T6 was investigated experimentally using the optical method of reflected caustics combined with a simplified high speed photography. A crack propagation testing configuration consisting of a three point bending specimen loaded In a drop weighting was used. It was found that prior to crack initiation the stress intensity factor time record calculated using the dynamic impact load and a static formula disagrees with the actual stress Intensity factor measured by caustics. The impact fracture tests are performed. With use of Al 7075-T6 band plate test specimens with a V-notch on their one side. The dynamic stress intensity factor K{sub id} are given. With this, the authors experimentally calculated the dynamic fracture toughness K{sub ID}.

  11. In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy

    SciTech Connect

    Feng, Zhili; Wang, Xun-Li; David, Stan A; Choo, Hahn; Hubbard, Camden R; Woo, Wan Chuck; Brown, D. W.; Clausen, B; An, Ke

    2007-01-01

    The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in situ, time resolved neutron diffraction technique. A method was developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld.

  12. In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy

    SciTech Connect

    Woo, Wan Chuck; Feng, Zhili; Wang, Xun-Li; Brown, D. W.; Clausen, B; An, Ke; Choo, Hahn; Hubbard, Camden R; David, Stan A

    2007-01-01

    The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in-situ, time-resolved neutron diffraction technique. A method is developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld.

  13. Laser peening without coating on aluminum alloy Al-6061-T6 using low energy Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Sathyajith, S.; Kalainathan, S.; Swaroop, S.

    2013-02-01

    The present study investigates the effect of laser peening without coating on aluminum alloy Al-6061-T6 with a 300 mJ infrared laser. The surface topography, microstructure, surface topography, surface residual stress and micro-hardness of peened and unpeened surfaces were studied. The study shows that laser peening without coating can significantly improve surface compressive stress and micro-hardness with trivial increase in surface roughness. Microstructure evaluation confirmed there was no near surface solidification after LPwC.

  14. Characterization of Retrogression and Re-Aging Heat Treatment of AA7075-T6 Using Nonlinear Acoustics and Eddy Current

    SciTech Connect

    Ananthula, Rajeshwar; Ko, Ray T.; Sathish, Shamachary; Blodgett, Mark

    2004-02-26

    Nonlinear acoustic parameter and eddy current methods have been utilized to characterize the heat treatment process of retrogression and re-aging of aluminum 7075-T6. The results of nonlinear acoustic parameter measurements show two distinct peaks at 30 minutes and 45 minutes of retrogression time. The phase of the through-thickness eddy current signal shows a minimum at 42 minutes of retrogression time. Application of combined methods for identifying the optimized properties in the material is discussed.

  15. Structural and functional characterization of KEOPS dimerization by Pcc1 and its role in t6A biosynthesis.

    PubMed

    Wan, Leo C K; Pillon, Monica C; Thevakumaran, Neroshan; Sun, Yulong; Chakrabartty, Avi; Guarné, Alba; Kurinov, Igor; Durocher, Daniel; Sicheri, Frank

    2016-08-19

    KEOPS is an ancient protein complex required for the biosynthesis of N6-threonylcarbamoyladenosine (t(6)A), a universally conserved tRNA modification found on all ANN-codon recognizing tRNAs. KEOPS consist minimally of four essential subunits, namely the proteins Kae1, Bud32, Cgi121 and Pcc1, with yeast possessing the fifth essential subunit Gon7. Bud32, Cgi121, Pcc1 and Gon7 appear to have evolved to regulate the central t(6)A biosynthesis function of Kae1, but their precise function and mechanism of action remains unclear. Pcc1, in particular, binds directly to Kae1 and by virtue of its ability to form dimers in solution and in crystals, Pcc1 was inferred to function as a dimerization module for Kae1 and therefore KEOPS. We now present a 3.4 Å crystal structure of a dimeric Kae1-Pcc1 complex providing direct evidence that Pcc1 can bind and dimerize Kae1. Further biophysical analysis of a complete archaeal KEOPS complex reveals that Pcc1 facilitates KEOPS dimerization in vitro Interestingly, while Pcc1-mediated dimerization of KEOPS is required to support the growth of yeast, it is dispensable for t(6)A biosynthesis by archaeal KEOPS in vitro, raising the question of how precisely Pcc1-mediated dimerization impacts cellular biology. PMID:27302132

  16. Estudio numerico y experimental del proceso de soldeo MIG sobre la aleacion 6063--T5 utilizando el metodo de Taguchi

    NASA Astrophysics Data System (ADS)

    Meseguer Valdenebro, Jose Luis

    improvement on mechanical properties in aluminum metal joint. Los procesos de soldadura por arco electrico representan unas de las tecnicas mas utilizadas en los procesos de fabricacion de componentes mecanicos en la industria moderna. Los procesos de soldeo por arco se han adaptado a las necesidades actuales, haciendose un modo de fabricacion flexible y versatil. Los resultados obtenidos numericamente en el proceso de soldadura son validados experimentalmente. Los principales metodos numericos mas empleados en la actualidad son tres, metodo por diferencias finitas, metodos por elementos finitos y metodo por volumenes finitos. El metodo numerico mas empleado para el modelado de uniones soldadas, es el metodo por elementos finitos, debido a que presenta una buena adaptacion a las condiciones geometricas y de contorno ademas de que existe una diversidad de programas comerciales que utilizan el metodo por elementos finitos como base de calculo. Este trabajo de investigacion presenta un estudio experimental de una union soldada mediante el proceso MIG de la aleacion de aluminio 6063-T5. El metodo numerico se valida experimentalmente aplicando el metodo de los elementos finitos con el programa de calculo ANSYS. Los resultados experimentales obtenidos son: las curvas de enfriamiento, el tiempo critico de enfriamiento t4/3, geometria del cordon, microdurezas obtenidas en la union soldada, zona afectada termicamente y metal base, dilucion del proceso, areas criticas intersecadas entre las curvas de enfriamiento y la curva TTP. Los resultados numericos son: las curvas del ciclo termico, que representan tanto el calentamiento hasta alcanzar la temperatura maxima y un posterior enfriamiento. Se calculan el tiempo critico de enfriamiento t4/3, el rendimiento termico y se representa la geometria del cordon obtenida experimentalmente. La zona afectada termicamente se obtiene diferenciando las zonas que se encuentran a diferentes temperaturas, las areas criticas intersecadas entre las

  17. Characterization of t(6;11)(p21;q12) in a renal-cell carcinoma of an adult patient.

    PubMed

    Pecciarini, Lorenza; Cangi, M Giulia; Lo Cunsolo, Crocifissa; Macri', Ettore; Dal Cin, Elena; Martignoni, Guido; Doglioni, Claudio

    2007-05-01

    Renal-cell carcinoma (RCC) constitutes a heterogeneous group of tumors with specific chromosome aberrations. Recently, a new small group of RCC, occurring in children and young adults, has been described as characterized by t(6;11)(p21;q12). It has been shown that this translocation results in the fusion of the 5' portion of the ALPHA gene (11q12) with the transcription factor gene TFEB (6p21). Herewith, we report the first complete cytogenetic and molecular characterization of a t(6;11)-positive RCC of an adult patient, a 54-year-old woman. The tumor was histologically defined as RCC with peculiar features and it was negative for epithelial markers and positive for melanocytic markers. Chromosome QFQ banding analysis of short-term cultured cells from the RCC showed t(6;11)(p21;q12) as the sole cytogenetic abnormality. The translocation was confirmed by FISH analysis. RT-PCR analysis, performed on total RNA isolated from both neoplastic and normal tissue samples, revealed an ALPHA-TFEB chimeric transcript in the tumor sample; sequencing of the RT-PCR product defined a novel TFEB gene breakpoint cluster region, broader than the one reported thus far. Western blot analysis showed a band at the expected size of wild-type TFEB in the neoplastic tissue compared to the normal sample, supporting that the fusion gene does not encode for a chimeric protein but it causes an upregulation of the wild-type TFEB. Our data contribute to define better this rare RCC type, which is typical not only of childhood but can also be found in adulthood. PMID:17285572

  18. A Williams syndrome patient with a familial t(6;7) translocation and deletion of the elastin gene

    SciTech Connect

    Pober, B.R.; Gibson, L.H.; Yang-Feng, T.L.

    1994-09-01

    Discovery of a {open_quotes}balanced{close_quotes} reciprocal translocation [46,XX,t(6;7)(q11.2;q11.23)] on routine amniocentesis prompted clinical and cytogenetic study of additional family members. The same t(6;7) translocation was found in the clincally normal father and in a sibling with Williams syndrome (WS). WS had been diagnosed previously according to clinical criteria including distinctive facial features, supravalvar aortic stenosis requiring surgical repair, dental abnormalties and developmental delay. A clinically normal female was delivered and the translocation was confirmed with a cord blood specimen. Hemizygosity for the gene, elastin, (which has been mapped to the chromosome 7 translocation breakpoint, 7q11.23, in this family) appears to be a cause of WS. We therefore investigated whether the t(6;7) in the phenotypically normal father represented more than a simple reciprocal translocation. FISH using a chromosome 7 specific library revealed no differences between the cytogenetically identical, yet phenotypically distinct, father and son. Hybridization with a cosmid MR127D4 containing elastin sequence showed that the WS patient was missing one allele from the derivative chromosome 7 whereas both his mother and father had two copies of the elastin gene. This family indicates that the de novo loss of one copy of the elastin gene produces the recognizable phenotype of Williams syndrome. Molecular characterization (with additional probes) of the extent of this de novo deletion near the translocation breakpoint is in progress. This information will be valuable for defining the WS-critical region and will lead to a better understanding of the molecular basis for WS.

  19. Electrochemical investigation on the hydrogen permeation behavior of 7075-T6 Al alloy and its influence on stress corrosion cracking

    NASA Astrophysics Data System (ADS)

    Zheng, Chuan-bo; Yan, Bing-hao; Zhang, Ke; Yi, Guo

    2015-07-01

    The hydrogen permeation behavior and stress corrosion cracking (SCC) susceptibility of precharged 7075-T6 Al alloy were investigated in this paper. Devanthan-Stachurski (D-S) cell tests were used to measure the apparent hydrogen diffusivity and hydrogen permeation current density of specimens immersed in 3.5wt% NaCl solution. Electrochemical experiment results show that the SCC susceptibility is low during anodic polarization. Both corrosion pits and hydrogen-induced cracking are evident in scanning electron microscope images after the specimens have been charging for 24 h.

  20. In vitro and QSAR studies of cucurbitacins on HepG2 and HSC-T6 liver cell lines.

    PubMed

    Bartalis, Judit; Halaweish, Fathi T

    2011-04-15

    The aim of this study was to evaluate cucurbitacins (Cucs) liver protective activity in vitro and conduct QSAR studies against lipophilicity and ab initio descriptors. Nine Cucs were isolated from Cucurbitaceae plants and eight prepared by C2-alkylation or C16-acylation. Ten Cucs demonstrated protective activity on human hepatocyte-derived HepG2 cells exposed to CCl(4) (EC(50)=2.4-45.3 μM) with good margin to toxicity (T/A). All Cucs exhibited anti-proliferative effect on serum-activated rat stellate cells, HSC-T6 (EC(50)=0.02-4.12 μM) with high T/A. While silybin is nontoxic, its protection is lower compared to Cuc D (3), iso-D (4), I (5), B (11), E (12), I-Me (6), L-Me (7), and E-Me (13) on both cell lines. Strong correlations were found for lipophilicity with both protection and toxicity on HepG2. Lipophilicity correlated only with toxicity on HSC-T6. Consequently, we suggest that Cucs are potential hepatoprotective agents against fibrosis that deserve further examination. PMID:21459003

  1. Immunodeficiency in RFM/(T6xRFM)F1 mouse chimaeras with lethal host-versus-graft syndrome.

    PubMed Central

    Hard, R C; Montour, J L; Fuchs, B A

    1995-01-01

    Rather than central tolerance, the perinatal inoculation of related F1 hybrid spleen cells into inbred mice may result in host-versus-graft (HVG) reactions manifested as transient autoimmunity, or as a lethal immunodeficiency syndrome. RFM/(T6xRFM)F1 chimaeras with lethal disease die in 30 days with lymphosplenomegaly, immune complexes and impaired immune responses. The present studies used in vitro proliferation assays to show that the HVG reaction caused hyperplasia sufficient to account for the lymphosplenomegaly, while also causing severe impairment of splenic and nodal cell responses to concanavalin A (Con A) and to bacterial lipopolysaccharide (LPS). By 25 days, HVG mice could not distinguish between self and non-self as judged by mixed lymphocyte reactions (MLR) to RFM, (T6xRFM)F1 and third party A/J cells. There were no indications that host cells reactive to F1 donor cells had undergone clonal deletion, anergy or expansion. Flow cytometry revealed that donor T lymphocytes achieved stable engraftment, mostly in the nodes, despite the HVG reaction. Taken together with previous observations, these studies showed that HVG reactions in young parent F1/chimaeras can result in an immunodeficiency state which is characterized by an early appearing, profound and persistent impairment of both host and donor T and B cell functions. The results suggest that HVG reactions can contribute directly to immune deficits seen after clinical allogeneic bone marrow transplantation. PMID:7743676

  2. An evaluation of the T-6A Texan (JPATS) initial functional performance of the CFIS laser assemblies

    NASA Astrophysics Data System (ADS)

    Blachowski, Thomas J.; Eccard, George; Thom, Travis

    2009-08-01

    The Indian Head Division, Naval Surface Warfare Center (IHDIV, NSWC) CAD Engineering Division is conducting a program to evaluate the laser components which comprise the Canopy Fracturing Initiation System (CFIS) currently installed on the T-6A Texan or JPATS (Joint Primary Aircraft Training System) aircraft. The T-6A Texan is the first aircraft used by the military to train future pilots. The CFIS is an element of the pilot emergency escape system which weakens the canopy in the path of the ejection seat. The CFIS is comprised of three differing configurations (Internal, External, and Seat Motion) which generate a laser pulse that is distributed through a fiber optic energy transmission system. This pulse, in turn, initiates explosive components which weaken the respective canopies. All of the CFIS laser types are flashlamp-pumped, neodymium glass lasers which are located at various positions in the aircraft cockpit area. This paper builds on the previous 2008 SPIE paper (Conference 7070) and presents further CAD Engineering Division test results and analysis which were utilized to evaluate the functional performance of the three CFIS laser signal generators after their being installed fleet applications over a period of time.

  3. The anti-hepatic fibrosis activity of ergosterol depended on upregulation of PPARgamma in HSC-T6 cells.

    PubMed

    Tai, Chen-Jei; Choong, Chen-Yen; Lin, Yu-Chun; Shi, Yeu-Ching; Tai, Cheng-Jeng

    2016-04-20

    Advanced glycation endproducts (AGEs) were shown to play an important role in metabolic syndrome and were suggested to contribute to the development of hepatic fibrosis. Evidence indicates that AGEs resulted in hepatic fibrosis coupled to the activation of the receptor for AGEs (RAGE) in hepatic stellate cells (HSCs). NADPH oxidase is downstream of the RAGE signaling pathway, resulting in an increase in reactive oxygen species (ROS), alpha-smooth muscle actin (alpha-SMA), RAGE, and matrix metalloproteinase-9 (MMP-9). This study was designed to evaluate the effects of ergosterol on RAGE signaling in HSC-T6 cells. Ergosterol suppressed the activation of HSC-T6 cells induced by AGEs, and attenuated overexpressions of alpha-SMA, MMP-9, and epithelial-mesenchymal transition (EMT) markers, including N-cadherin and vimentin. We also found that these inhibitory effects of ergosterol on the activation of HSCs were dependent on peroxisome proliferator-activated receptor-gamma (PPARgamma) confirmed by PPARgamma reporter assay and PPARgamma knockdown. In addition, ergosterol also showed an inhibitory effect on the generation of AGEs, fructosamine, and α-dicarbonyl compounds in this study. Our results show that ergosterol can be used as a protective agent against hepatic fibrosis caused by induction of AGEs. PMID:27040153

  4. Simulation of d(7Be,t)6Be with Fresco, and investigation of resonant states of 6Be

    NASA Astrophysics Data System (ADS)

    Pelham, Timothy

    2008-10-01

    An ongoing study is presented into the resonant states of 6Be via simulation of d(7Be,t)6Be with Fresco to investigate the results of ``Searching for resonances in the unbound 6Be nucleus'' a paper by K.Y. Chae [1]. In this paper the d(7Be,t)6Be reaction was studied to search for resonances in the 6Be nucleus that may be used to increase our knowledge of the 3He(3He,2p)4He reaction. A 100-MeV 7Be beam from the Holifield Radioactive Ion Beam Facility (HRIBF) was used to bombard CD2 targets, and tritons were detected by the Silicon Detector Array (SIDAR). It was concluded that a combination of reaction mechanisms are necessary to account for the observed triton energy spectrum. This will be further investigated by simulating the various reaction mechanisms with Fresco to try to reproduce and explain these results. Preliminary Results will be presented.

  5. A study of fatigue and fracture in 7075-T6 aluminum alloy in vacuum and air environments

    NASA Technical Reports Server (NTRS)

    Hudson, C. M.

    1973-01-01

    Axial load fatigue life, fatigue-crack propagation, and fracture toughness experiments were conducted on sheet specimens made of 7075-T6 aluminum alloy. These experiments were conducted at pressures ranging from atmospheric to 5 x 10 to the minus 8th torr. Analysis of the results from the fatigue life experiments indicated that for a given stress level, lower air pressures produced longer fatigue lives. At a pressure of 5 x 10 to the minus 8th torr fatigue lives were 15 or more times as long as at atmospheric pressure. Analysis of the results from the fatigue crack propagation experiments indicated that for small stress intensity factor ranges the fatigue crack propagation rates were up to twice as high at atmospheric pressure as in vacuum. The fracture toughness of 7075-T6 was unaffected by the vacuum environment. Fractographic examination showed that specimens tested in both vacuum and air developed fatigue striations. Considerably more striations developed on specimens tested at atmospheric pressure, however.

  6. A molecular dynamics investigation into the size-dependent buckling behavior of a novel three-dimensional metallic carbon nanostructure (T6)

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Ajori, S.; Hassani, R.

    2016-09-01

    The buckling behavior of a novel three-dimensional metallic carbon nanostructure known as T6 is investigated herein employing the molecular dynamics (MD) simulations. The models are prepared on the basis of two beam- and plate-like structures to study the effects of size and geometry on the critical buckling force and critical strain. It is observed that the range of critical force for the beam-like and plate-like T6 with different geometrical parameters is approximately identical. Moreover, it is demonstrated that the critical buckling force decreases and increases by increasing the length and the width of T6, respectively. Moreover, it is shown that critical strain of beam-like T6 decreases by increasing the length, whereas, in the case of plate-like T6, the critical strain only fluctuates around 2% by increasing the width. It is further found that the buckling parameters of T6 are not comparable with those of single-walled carbon nanotubes (SWCNTs) and graphene with a relatively similar dimension. The critical buckling force and critical strain of T6 are considerably smaller than those of SWCNT and larger than those of graphene.

  7. Investigation of Hot Cracking Behavior in Transverse Mechanically Arc Oscillated Autogenous AA2014 T6 TIG Welds

    NASA Astrophysics Data System (ADS)

    Biradar, N. S.; Raman, R.

    2012-09-01

    Hot cracking studies on autogenous AA2014 T6 TIG welds were carried out. Significant cracking was observed during linear and circular welding test (CWT) on 4-mm-thick plates. Weld metal grain structure and amount of liquid distribution during the terminal stages of solidification were the key cause for hot cracking in aluminum welds. Square-wave AC TIG welding with transverse mechanical arc oscillation (TMAO) was employed to study the cracking behavior during linear and CWT. TMAO welds with amplitude = 0.9 mm and frequency = 0.5 Hz showed significant reduction in cracking tendency. The increase in cracking resistance in the arc-oscillated weld was attributed to grain refinement and improved weld bead morphology, which improved the weld metal ductility and uniformity, respectively, of residual tensile stresses that developed during welding. The obtained results were comparable to those of reported favorable results of electromagnetic arc oscillation.

  8. UV radiation facilitates methotrexate resistance and amplification of the dihydrofolate reductase gene in cultured 3T6 mouse cells

    SciTech Connect

    Tlsty, T.D.; Brown, P.C.; Schimke, R.T.

    1984-06-01

    Pretreatment of 3T6 murine cells with the carcinogen UV radiation or N-acetoxy-N-acetylaminofluorene increased the number of methotrexate-resistant colonies. This carcinogen-induced enhancement was seen only at low toxicities. The enhancement was transient and was observed at its maximum when cells were subjected to methotrexate selection 12 to 24 h after treatment. The addition of a tumor-promoting agent, 12-O-tetradecanoylphorbol-13-acetate, during or after carcinogen treatment further enhanced this effect. A large proportion of the resistant colonies had an increase in the dihydrofolate reductase gene copy number and the relative proportions of colonies with amplified genes were similar, regardless of whether selected cells were untreated, treated with carcinogen, or treated with carcinogen plus promoter. We discuss some of the variables which both enhance the generation and improve the detection of methotrexate-resistant colonies, as well as certain implications of our results for the generation and mechanism of gene amplification.

  9. Corrosion behavior of the friction-stir-welded joints of 2A14-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Qin, Hai-long; Zhang, Hua; Sun, Da-tong; Zhuang, Qian-yu

    2015-06-01

    The corrosion behavior of friction-stir-welded 2A14-T6 aluminum alloy was investigated by immersion testing in immersion exfoliation corrosion (EXCO) solution. Electrochemical measurements (open circuit potential, potentiodynamic polarization curves, and electrochemical impedance spectroscopy), scanning electron microscopy, and energy dispersive spectroscopy were employed for analyzing the corrosion mechanism. The results show that, compared to the base material, the corrosion resistance of the friction-stir welds is greatly improved, and the weld nugget has the highest corrosion resistance. The pitting susceptibility originates from the edge of Al-Cu-Fe-Mn-Si phase particles as the cathode compared to the matrix due to their high self-corrosion potential. No corrosion activity is observed around the θ phase (Al2Cu) after 2 h of immersion in EXCO solution.

  10. Effect of laser peening with different energies on fatigue fracture evolution of 6061-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Sheng, J.; Huang, S.; Zhou, J. Z.; Lu, J. Z.; Xu, S. Q.; Zhang, H. F.

    2016-03-01

    To deeply understand the effect of laser peening (LP) with different laser pulse energies on 6061-T6 aluminum alloy, the fatigue fracture morphologies evolution process at various fatigue crack growth (FCG) stages and the corresponding strengthen mechanism were investigated. At the initial stage of FCG, more fatigue micro-cliffs were found after LP, while the fatigue striation spacing simultaneously reduced. A "stop-continue" phenomenon of crack propagation was discovered for laser peened samples. The fatigue striation spacing at the middle stage of FCG increased significantly while compared with that at the initial stage, in addition, the fatigue striation spacing decreased with an increase in laser pulse energy. Fracture morphologies in transition region of laser peened samples exhibit a mixing fracture characteristic of striations and dimples. The laser peened sample with laser pulse energy of 7 J presents more circuitous growing paths. Due to the complex stress state induced by LP, dimples with different sizes appeared in the final fracture region.

  11. Effect of T6 heat treatment on the microstructural and mechanical properties of Al-Si-Cu-Mg alloys

    NASA Astrophysics Data System (ADS)

    Patel, Dhruv; Davda, Chintan; Solanki, P. S.; Keshvani, M. J.

    2016-05-01

    In this communication, it is aimed to optimize the conditions for T6 heat treatment of permanent die cast Al-Si-Cu-Mg alloys. Various solutionizing temperatures, aging treatments and soaking times were used to improve / modify the mechanical properties of presently studied alloys. Formation mechanism of the particles was understood by carrying out optical microscopy and energy dispersive X-ray (EDX) spectroscopy measurements. Spherical particles of alloys were studied for their microstructural properties using scanning electron microscopy (SEM). Microhardness test was performed to investigate their mechanical properties. Dependence of cluster formation and microhardness of the alloys on the adequate solutionizing temperature, aging treatment and soaking time has been discussed in detail.

  12. Crystallization and preliminary X-ray analysis of alpha-D-glucuronidase from Bacillus stearothermophilus T-6.

    PubMed

    Teplitsky, A; Shulami, S; Moryles, S; Zaide, G; Shoham, Y; Shoham, G

    1999-04-01

    alpha-D-Glucuronidases cleave the alpha-1,2-glycosidic bond of the 4-O-methyl-alpha-D-glucuronic acid side chain in xylan. Of the xylan-debranching hydrolases, these enzymes are the least studied and characterized. The alpha-glucuronidase gene (aguA) from Bacillus stearothermophilus T-6 has been cloned, sequenced and overproduced in Escherichia coli. The gene encodes for a protein of 679 amino acids with a calculated molecular weight of 78480 and a pI of 5.42. alpha-Glucuronidase T-6 shows high homology to the alpha-glucuronidases of Thermotoga maritima (60% identity) and of Tri-choderma reesei (44% identity). Based on the amino-acid sequence similarity, it is likely that these enzymes represent a new class of glycosyl hydrolases. Crystallographic studies of alpha-glucuronidase T-6 were initiated to study the mechanism of catalysis, as well as to provide a structural basis for rational introduction of enhanced thermostability by site-specific mutagenesis. In this report, the crystallization and preliminary crystallographic characterization of the native alpha-glucuronidase T-6 enzyme is described. Two crystal forms were found suitable for detailed crystal structure analysis. The T1 form was obtained by the vapour-diffusion method using PEG 4000 as a precipitant and 2-propanol as an organic additive. The crystals belong to a primitive tetragonal crystal system (space group P41212 or P43212) with unit-cell dimensions a = b = 76.1 and c = 331.2 A. These crystals are mechanically strong, are stable in the X--ray beam and diffract X-rays to better than 2.4 A resolution. A full 3.0 A resolution diffraction data set (97.3% completeness, Rmerge 9.8%) has recently been collected on one crystal at room temperature using a rotating-anode X-ray source and an R-AXIS IIc imaging-plate detector. The M1 form was obtained and characterized by similar techniques. The best crystallization occurred at a slightly lower pH and a lower concentration of 2-propanol. The crystals belong to

  13. Two new oleanane-type triterpenoids from Platycodi Radix and anti-proliferative activity in HSC-T6 cells.

    PubMed

    Zhan, Qin; Zhang, Feng; Sun, Lianna; Wu, Zhijun; Chen, Wansheng

    2012-01-01

    Two new oleanane-type triterpenoids, named platycodonoids A and B (1, 2), together with five known saponins, including platycodin D (3), deapioplatycodin D (4), 3-O-β-D-glucopyranosyl polygalacic acid (5), 3-O-β-D-glucopyranosyl platycodigenin (6) and polygalacin D (7), were isolated from the roots of Platycodon grandiflorum. On the basis of spectral data and chemical evidence, the structures of the new compounds were elucidated as 2β,3β,23,24-tetrahydroxy-28-nor-olean-12-en-16-one (1) and 2β,3β,23,24- tetrahydroxy-28-nor-olean-12-en-16-one-3-O-β-D-glucopyranoside (2). Compounds 1-7 were evaluated for their in vitro anti-proliferative activity against the HSC-T6 cell line. PMID:23519261

  14. Laser shock processing to improve residual stresses with and without paint layer on 6061-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Gomez-Rosas, G.; Rubio-Gonzalez, C.; Ocaña, J. L.; Molpeceres, C.; Porro, J. A.; Morales, M.; Casillas, F. J.; Mora-Gonzalez, M.; Chi-Moreno, W.

    2007-03-01

    Laser shock processing (LSP) or laser shock peening has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduce fatigue crack growth rate. We present a configuration and results in the LSP concept for metal surface treatments in underwater laser irradiation at 1064 nm with and without a thin surface paint layer. A convergent lens is used to deliver 1, 2 J/cm2 with a 8 ns laser FWHM pulse produced by a 10 Hz, Q-switched Nd:YAG laser with a spot diameter of a 1,5 mm moving forward along the workpiece. A LSP configuration with experimental results using a pulse density of 5000 pulses/cm2 in 6061-T6 aluminum samples are presented.

  15. Effect of Welding Speeds on Mechanical Properties of Level Compensation Friction Stir Welded 6061-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Wen, Quan; Yue, Yumei; Ji, Shude; Li, Zhengwei; Gao, Shuangsheng

    2016-04-01

    In order to eliminate the flash, arc corrugation and concave in weld zone, level compensation friction stir welding (LCFSW) was put forward and successfully applied to weld 6061-T6 aluminum alloy with varied welding speed at a constant tool rotational speed of 1,800 rpm in the present study. The glossy joint with equal thickness of base material can be attained, and the shoulder affected zone (SAZ) was obviously reduced. The results of transverse tensile test indicate that the tensile strength and elongation reach the maximum values of 248 MPa and 7.1% when the welding speed is 600 mm/min. The microhardness of weld nugget (WN) is lower than that of base material. The tensile fracture position locates at the heat affected zone (HAZ) of the advancing side (AS), where the microhardness is the minimum. The fracture surface morphology represents the typical ductile fracture.

  16. Crystallization and preliminary crystallographic analysis of a family 43 β-d-xylosidase from Geobacillus stearothermophilus T-6

    SciTech Connect

    Brüx, Christian; Niefind, Karsten; Ben-David, Alon; Leon, Maya; Shoham, Gil; Shoham, Yuval; Schomburg, Dietmar

    2005-12-01

    The crystallization and preliminary X-ray analysis of a β-d-xylosidase from G. stearothermophilus T-6, a family 43 glycoside hydrolase, is described. Native and catalytic inactive mutants of the enzymes were crystallized in two different space groups, orthorhombic P2{sub 1}2{sub 1}2 and tetragonal P4{sub 1}2{sub 1}2 (or the enantiomorphic space group P4{sub 3}2{sub 1}2), using a sensitive cryoprotocol. The latter crystal form diffracted X-rays to a resolution of 2.2 Å. β-d-Xylosidases (EC 3.2.1.37) are hemicellulases that cleave single xylose units from the nonreducing end of xylooligomers. In this study, the crystallization and preliminary X-ray analysis of a β-d-xylosidase from Geobacillus stearothermophilus T-6 (XynB3), a family 43 glycoside hydrolase, is described. XynB3 is a 535-amino-acid protein with a calculated molecular weight of 61 891 Da. Purified recombinant native and catalytic inactive mutant proteins were crystallized and cocrystallized with xylobiose in two different space groups, P2{sub 1}2{sub 1}2 (unit-cell parameters a = 98.32, b = 99.36, c = 258.64 Å) and P4{sub 1}2{sub 1}2 (or the enantiomorphic space group P4{sub 3}2{sub 1}2; unit-cell parameters a = b = 140.15, c = 233.11 Å), depending on the detergent. Transferring crystals to cryoconditions required a very careful protocol. Orthorhombic crystals diffract to 2.5 Å and tetragonal crystals to 2.2 Å.

  17. ATGL and CGI-58 are lipid droplet proteins of the hepatic stellate cell line HSC-T6.

    PubMed

    Eichmann, Thomas O; Grumet, Lukas; Taschler, Ulrike; Hartler, Jürgen; Heier, Christoph; Woblistin, Aaron; Pajed, Laura; Kollroser, Manfred; Rechberger, Gerald; Thallinger, Gerhard G; Zechner, Rudolf; Haemmerle, Günter; Zimmermann, Robert; Lass, Achim

    2015-10-01

    Lipid droplets (LDs) of hepatic stellate cells (HSCs) contain large amounts of vitamin A [in the form of retinyl esters (REs)] as well as other neutral lipids such as TGs. During times of insufficient vitamin A availability, RE stores are mobilized to ensure a constant supply to the body. To date, little is known about the enzymes responsible for the hydrolysis of neutral lipid esters, in particular of REs, in HSCs. In this study, we aimed to identify LD-associated neutral lipid hydrolases by a proteomic approach using the rat stellate cell line HSC-T6. First, we loaded cells with retinol and FAs to promote lipid synthesis and deposition within LDs. Then, LDs were isolated and lipid composition and the LD proteome were analyzed. Among other proteins, we found perilipin 2, adipose TG lipase (ATGL), and comparative gene identification-58 (CGI-58), known and established LD proteins. Bioinformatic search of the LD proteome for α/β-hydrolase fold-containing proteins revealed no yet uncharacterized neutral lipid hydrolases. In in vitro activity assays, we show that rat (r)ATGL, coactivated by rat (r)CGI-58, efficiently hydrolyzes TGs and REs. These findings suggest that rATGL and rCGI-58 are LD-resident proteins in HSCs and participate in the mobilization of both REs and TGs. PMID:26330055

  18. Prediction of hardness minimum locations during natural aging in an aluminum alloy 6061-T6 friction stir weld

    SciTech Connect

    Woo, Wan Chuck; Choo, Hahn; Feng, Zhili; Withers, Prof Philip

    2009-01-01

    This study describes a simple model that can predict the evolution of hardness distribution as a function of natural aging time in a heat-treatable 6061-T6 Al alloy plate subjected to friction stir welding (FSW). First, two dimensional thermal distributions were simulated as a function of time in the FSW plate by finite element modeling. Second, the hardness changes during natural aging were measured as a function of aging time for a number of Al specimens that had been previously isothermally heat-treated to different hold temperatures in order to determine the natural aging kinetics. Finally, the simulated temperature profiles and the natural aging kinetics were correlated to predict the hardness profiles in the FSW plate. The predicted hardness variations are consistent with measured hardness profiles in that the location of minimum hardness moves away from the centerline as the aging time and/or heat input increases. The hardness variation was also related to the location of failure in cross-weld tensile samples.

  19. On Residual Stresses in Resistance Spot-Welded Aluminum Alloy 6061-T6: Experimental and Numerical Analysis

    NASA Astrophysics Data System (ADS)

    Afshari, D.; Sedighi, M.; Karimi, M. R.; Barsoum, Z.

    2013-12-01

    In this study, an electro-thermal-structural-coupled finite element (FE) model and x-ray diffraction residual stress measurements have been utilized to analyze distribution of residual stresses in an aluminum alloy 6061-T6 resistance spot-welded joint with 2-mm-thickness sheet. Increasing the aluminum sheet thickness to more than 1 mm leads to creating difficulty in spot-welding process and increases the complexity of the FE model. The electrical and thermal contact conductances, as mandatory factors are applied in contact areas of electrode-workpiece and workpiece-workpiece to resolve the complexity of the FE model. The physical and mechanical properties of the material are defined as thermal dependent to improve the accuracy of the model. Furthermore, the electrodes are removed after the holding cycle using the birth-and-death elements method. The results have a good agreement with experimental data obtained from x-ray diffraction residual stress measurements. However, the highest internal tensile residual stress occurs in the center of the nugget zone and decreases toward nugget edge; surface residual stress increases toward the edge of the welding zone and afterward, the area decreases slightly.

  20. Effects of Different Filler Metals on the Mechanical Behaviors of GTA Welded AA7A52(T6)

    NASA Astrophysics Data System (ADS)

    Shu, Fengyuan; Lv, Yaohui; Liu, Yuxin; Lin, Jianjun; Sun, Zhe; Xu, Binshi; He, Peng

    2014-06-01

    ER4043, ER5356, and AA7A52 on behalf of the Al-Si, Al-Mg, and Al-Zn-Mg-based welding material, respectively, were chosen as the filler metal to weld AA7A52(T6) plates by GTAW. The variance in mechanical performances of the joints caused by the various filler materials was investigated with reference to the SEM and EDS test results for the weld seam and the fracture surface. Failure was found in the seam for all the welded joints. With regard to the joint obtained with ER4043 welding wire, the total elongation was limited by the brittle intergranular compound Mg2Si of which Mg was introduced by convection mass transfer. As for the other two welds, the content ratio of Zn and Mg was found to play the dominant role in deciding the mechanical properties of the intergranular Mg-Zn compounds which were responsible for the tensile behavior of the joints. The content ratio (wt.%) of beyond 2:1 gave birth to the strengthening phase MgZn2 leading to a ductile fracture. Cr in the seam obtained with AA7A52 filler metal was found to enhance the strength of the joint through isolated particles.

  1. ATGL and CGI-58 are lipid droplet proteins of the hepatic stellate cell line HSC-T6[S

    PubMed Central

    Eichmann, Thomas O.; Grumet, Lukas; Taschler, Ulrike; Hartler, Jürgen; Heier, Christoph; Woblistin, Aaron; Pajed, Laura; Kollroser, Manfred; Rechberger, Gerald; Thallinger, Gerhard G.; Zechner, Rudolf; Haemmerle, Günter; Zimmermann, Robert; Lass, Achim

    2015-01-01

    Lipid droplets (LDs) of hepatic stellate cells (HSCs) contain large amounts of vitamin A [in the form of retinyl esters (REs)] as well as other neutral lipids such as TGs. During times of insufficient vitamin A availability, RE stores are mobilized to ensure a constant supply to the body. To date, little is known about the enzymes responsible for the hydrolysis of neutral lipid esters, in particular of REs, in HSCs. In this study, we aimed to identify LD-associated neutral lipid hydrolases by a proteomic approach using the rat stellate cell line HSC-T6. First, we loaded cells with retinol and FAs to promote lipid synthesis and deposition within LDs. Then, LDs were isolated and lipid composition and the LD proteome were analyzed. Among other proteins, we found perilipin 2, adipose TG lipase (ATGL), and comparative gene identification-58 (CGI-58), known and established LD proteins. Bioinformatic search of the LD proteome for α/β-hydrolase fold-containing proteins revealed no yet uncharacterized neutral lipid hydrolases. In in vitro activity assays, we show that rat (r)ATGL, coactivated by rat (r)CGI-58, efficiently hydrolyzes TGs and REs. These findings suggest that rATGL and rCGI-58 are LD-resident proteins in HSCs and participate in the mobilization of both REs and TGs. PMID:26330055

  2. A study on ultra-precision machining technique for Al6061-T6 to fabricate space infrared optics

    NASA Astrophysics Data System (ADS)

    Ryu, Geun-man; Lee, Gil-jae; Hyun, Sang-won; Sung, Ha-yeong; Chung, Euisik; Kim, Geon-hee

    2014-08-01

    In this paper, analysis of variance on designed experiments with full factorial design was applied to determine the optimized machining parameters for ultra-precision fabrication of the secondary aspheric mirror, which is one of the key elements of the space cryogenic infrared optics. A single point diamond turning machine (SPDTM, Nanotech 4μpL Moore) was adopted to fabricate the material, AL6061-T6, and the three machining parameters of cutting speed, feed rate and depth of cut were selected. With several randomly assigned experimental conditions, surface roughness of each condition was measured by a non-contact optical profiler (NT2000; Vecco). As a result of analysis using Minitab, the optimum cutting condition was determined as following; cutting speed: 122 m/min, feed rate: 3 mm/min and depth of cut: 1 μm. Finally, a 120 mm diameter aspheric secondary mirror was attached to a particularly designed jig by using mixture of paraffin and wax and successfully fabricated under the optimum machining parameters. The profile of machined surface was measured by a high-accuracy 3-D profilometer(UA3P; Panasonic) and we obtained the geometrical errors of 30.6 nm(RMS) and 262.4 nm(PV), which satisfy the requirements of the space cryogenic infrared optics.

  3. High strain rate properties of an SiC{sub W}/2124-T6 aluminum composite at elevated temperatures

    SciTech Connect

    Guden, M.; Hall, I.W.

    1998-07-03

    Metal matrix composites, (MMC`s) provide several important advantages over unreinforced metals and alloys. Among these, higher moduli and yield stresses and enhanced thermo-mechanical properties are normally considered important in structural applications of MMC`s. It is also possible that MMC`s may be exposed to loading conditions involving high strain rates during service, for example, components of a car in collision with another or turbine blades hit by ingestion of foreign objects. In such situations of rapidly increasing loading conditions, the material property response may be considerably different from that which applies during slow loading of normal quasi-static testing and, consequently, dynamic mechanical properties are of increasing interest and importance. Several studies involving dynamic deformation of a SiC{sub W}/2124-T6 Al MMC have already been conducted using tension, shear, compression and projectile impact testing. The purpose of the present study was to extend the high strain rate data to include high temperature effects. Mechanical test results and microstructural observations of features of dynamic deformation have been compared with data from the unreinforced alloy to obtain more complete information on the dynamic response of the composite.

  4. Modeling of Residual Stresses and Property Distributions in Friction Stir Welds of Aluminum Alloy 6061-T6

    SciTech Connect

    Feng, Zhili; David, Stan A; Wang, Xun-Li; Sklad, Philip S

    2007-01-01

    An integrated thermal-metallurgical-mechanical model is used to analyze and provide insights into the formation of the residual stress and the changes in microstructure and property of Al6061-T6 friction stir welds. The simulations were conducted by means of a three-dimensional finite element model that accounts for the phenomena of frictional heating, weld microstructure and strength changes due to dissolution and reprecipitation of the hardening precipitate particles, and the mechanical workpiece/tool contact during the friction stir welding (FSW) process. The model predictions were confirmed by experimental measurement data from previous studies. For the friction stir welds investigated, it was found that the residual stress distribution is strongly dependent on the welding process parameters and the degree of material softening caused by welding. The recovery of material strength from natural aging does not increase the residual stress in the weld. The failure of friction stir weld under tensile load is controlled by the combination of the reduction in strength and the residual stresses in the heat affected zone (HAZ).

  5. Chloride Ion Activity and Susceptibility of Al Alloys 7075-T6 and 5083-H131 to Stress Corrosion Cracking

    NASA Astrophysics Data System (ADS)

    Ricker, R. E.; Lee, E. U.; Taylor, R.; Lei, C.; Pregger, B.; Lipnickas, E.

    2013-03-01

    The influence of chloride ion activity on the susceptibility of aluminum alloys 5083-H131 and 7075-T6 to stress corrosion cracking (SCC) was investigated by conducting slow strain-rate tensile tests at a strain-rate of 10-7 s-1 in naturally aerated aqueous solutions with varying NaCl mass fraction (0.001 to 20 pct) and in a 3.5 pct mass fraction NaCl solution with varying strain-rates (10-8 to 10-4 s-1). This study found that both alloys exhibited reduced strengths and failure strains (times) in the solutions compared with laboratory air. The extent of these reductions was greater in alloy 5083 for the conditions examined. The strength and ductility of both alloys decreased with chloride ion activity in a manner that indicates a chemical reaction is responsible. The strength and ductility of both alloys decreased with strain-rate in a sigmoidal manner, but the transition in alloy 7075 occurred at slower strain-rates of approximately two orders of magnitude. It was deduced that the chloride ion interacts chemically with the passivated surface in the potential gradient at the crack tip to cause SCC. While no mechanism of cracking can be eliminated on the basis of these results alone, the results are consistent with the hypothesis that the absorbed hydrogen causes cracking in alloy 7075 while cracking in 5083 is the result of a dissolution mechanism.

  6. t(6;11) renal cell carcinoma (RCC): expanded immunohistochemical profile emphasizing novel RCC markers and report of 10 new genetically confirmed cases.

    PubMed

    Smith, Nathaniel E; Illei, Peter B; Allaf, Mohamed; Gonzalez, Nilda; Morris, Kerry; Hicks, Jessica; Demarzo, Angelo; Reuter, Victor E; Amin, Mahul B; Epstein, Jonathan I; Netto, George J; Argani, Pedram

    2014-05-01

    Renal cell carcinomas (RCCs) harboring the t(6;11)(p21;q12) translocation were first described in 2001 and recently recognized by the 2013 International Society of Urological Pathology Vancouver Classification of Renal Neoplasia. Although these RCCs are known to label for melanocytic markers HMB45 and Melan A and the cysteine protease cathepsin K by immunohistochemistry (IHC), a comprehensive IHC profile has not been reported. We report 10 new t(6;11) RCCs, all confirmed by break-apart TFEB fluorescence in situ hybridization. A tissue microarray containing 6 of these cases and 7 other previously reported t(6;11) RCCs was constructed and immunolabeled for 21 different antigens. Additional whole sections of t(6;11) RCC were labeled with selected IHC markers. t(6;11) RCC labeled diffusely and consistently for cathepsin K and Melan A (13 of 13 cases) and almost always at least focally for HMB45 (12 of 13 cases). They labeled frequently for PAX8 (14 of 23 cases), CD117 (10 of 14 cases), and vimentin (9 of 13 cases). A majority of cases labeled at least focally for cytokeratin Cam5.2 (8 of 13 cases) and CD10 and RCC marker antigen (10 of 14 cases each). In contrast to a prior study's findings, only a minority of cases labeled for Ksp-cadherin (3 of 19 cases). The median H score (product of intensity score and percentage labeling) for phosphorylated S6, a marker of mTOR pathway activation, was 101, which is high relative to most other RCC subtypes. In summary, IHC labeling for PAX8, Cam5.2, CD10, and RCC marker antigen supports classification of the t(6;11) RCC as carcinomas despite frequent negativity for broad-spectrum cytokeratins and EMA. Labeling for PAX8 distinguishes the t(6;11) RCC from epithelioid angiomyolipoma, which otherwise shares a similar immunoprofile. CD117 labeling is more frequent in the t(6;11) RCC compared with the related Xp11 translocation RCC. Increased pS6 expression suggests a possible molecular target for the uncommon t(6;11) RCCs that

  7. Murine interferon system regulation: isolation and characterization of a mutant 3T6 cell engaged in the semiconstitutive synthesis of interferon.

    PubMed

    Jarvis, A P; Colby, C

    1978-06-01

    We describe the isolation and characterization of a virus-resistant mutant of murine 3T6 cells. The mutant, designated 3T6-VrB2, displays a high degree of resistance to infection by members of the toga-, rhabdo- and picornavirus classes. The level of this resistance to infection is similar to the parent 3T6 pretreated with approximately 100 lU/ml of interferon. Upon co-cultivation of 3T6-VrB2 cells with interferon-sensitive mouse cells, an antiviral state is induced in the latter cells as measured by a reduction of virus yield following infection. The nature of the induction is defined by a series of experiments using anti-mouse interferon antiserum. In the presence of this antiserum, the ability of the mutant to induce an antiviral state in interferon-sensitive mouse cells upon co-cultivation is eliminated. Additionally, growth of the mutant cells in the presence of this antiserum causes a reversal of the virus-resistant phenotype. Our results indicate that 3T6-VrB2 contains a mutation affecting the regulation of the murine interferon system such that the cell is engaged in the semiconstitutive synthesis of interferon. PMID:208779

  8. Creep properties of forged 2219 T6 aluminum alloy shell of general-purpose heat source-radioisotope thermoelectric generator

    SciTech Connect

    Hammond, J.P.

    1981-12-01

    The shell (2219 T6 aluminum forging) of the General Purpose Heat Source-Radioisotope Thermoelectric Generator was designed to retain the generator under sufficient elastic stress to secure it during space flight. A major concern was the extent to which the elastic stress would relax by creep. To determine acceptability of the shell construction material, the following proof tests simulating service were performed: 600 h of testing at 270/sup 0/C under 24.1 MPa stress followed by 10,000 h of storage at 177/sup 0/C under 55.1 MPa, both on the ground; and 10,000 h of flight in space at 270/sup 0/C under 34.4 MPa stress. Additionally, systematic creep testing was performed at 177 and 260/sup 0/C to establish creep design curves. The creep tests performed at 177/sup 0/C revealed comparatively large amounts of primary creep followed by small amounts of secondary creep. The early creep is believed to be abetted by unstable substructures that are annealed out during testing at this temperature. The creep tests performed at 270/sup 0/C showed normal primary creep followed by large amounts of secondary creep. Duplicate proof tests simulating the ground exposure conditions gave results that were in good agreement. The proof test simulating space flight at 270/sup 0/C gave 0.11% primary creep followed by 0.59% secondary creep. About 10% of the second-stage creep was caused by four or five instantaneous strains, which began at the 4500-h mark. One or two of these strain bursts, occurred in each of several other tests at 177 and 260/sup 0/C but were assessed as very moderate in magnitude. The effect is attributable to a slightly microsegregated condition remaining from the original cast structure.

  9. Barrier anodic coatings formed on 6061-T6 aluminum alloy in electrolytes containing different ethanol to water ratios

    SciTech Connect

    Panitz, J.K.G.; Sharp, D.J.; Martinez, F.E.; Merrill, R.M.; Ward, K.J.

    1988-12-01

    We have studied barrier anodic film formation on 6061-T6 aluminum alloy substrates as a function of electrolyte composition for five mixtures of ammonium tartrate dissolved in water and diluted with different amounts of ethanol. The effects of electrolyte temperatures within the range of 18/degree/C to 38/degree/C were explored. The results of this study indicate that the best dielectric coatings and the shortest processing times occur for the 100% water-ammonium tartrate electrolyte. The second best coatings and processing times occur in conjunction with the use of 98% ethanol, 2% water plus ammonium tartrate electrolyte. In general, visibly flawed coatings, scintillation events at cell voltages in excess of approximately 750-800 volts and/or abnormally long processing times occur in conjunction with the use of electrolyte mixtures containing 20%, 60%, and 90% water. We analysed samples of electrolyte as a function of usage, and evaluated the composition of the coatings using Fourier Transform Infrared Analysis to better understand the mechanisms which contribute to anodic coating growth that result in the observed variations in the dielectric properties. All of the coatings exhibited similar compositions except with regard to the amount of CO2 that was physisorbed in the coatings. The dielectrically inferior coatings that were typically produced by the electrolytes containing ethanol contain substantially more CO2 than the coatings grown in the 100% water-based electrolyte. These results strongly suggest that the ethanol in the electrolyte oxidizes and forms CO2 which is incorporated in the coatings and results in inferior dielectric properties. 8 refs., 7 figs.

  10. Preliminary crystallographic analysis of Xyn52B2, a GH52 β-D-xylosidase from Geobacillus stearothermophilus T6.

    PubMed

    Dann, Roie; Lansky, Shifra; Lavid, Noa; Zehavi, Arie; Belakhov, Valery; Baasov, Timor; Dvir, Hay; Manjasetty, Babu; Belrhali, Hassan; Shoham, Yuval; Shoham, Gil

    2014-12-01

    Geobacillus stearothermophilus T6 is a thermophilic bacterium that possesses an extensive hemicellulolytic system, including over 40 specific genes that are dedicated to this purpose. For the utilization of xylan, the bacterium uses an extracellular xylanase which degrades xylan to decorated xylo-oligomers that are imported into the cell. These oligomers are hydrolyzed by side-chain-cleaving enzymes such as arabinofuranosidases, acetylesterases and a glucuronidase, and finally by an intracellular xylanase and a number of β-xylosidases. One of these β-xylosidases is Xyn52B2, a GH52 enzyme that has already proved to be useful for various glycosynthesis applications. In addition to its demonstrated glycosynthase properties, interest in the structural aspects of Xyn52B2 stems from its special glycoside hydrolase family, GH52, the structures and mechanisms of which are only starting to be resolved. Here, the cloning, overexpression, purification and crystallization of Xyn52B2 are reported. The most suitable crystal form that has been obtained belonged to the orthorhombic P212121 space group, with average unit-cell parameters a = 97.7, b = 119.1, c = 242.3 Å. Several X-ray diffraction data sets have been collected from flash-cooled crystals of this form, including the wild-type enzyme (3.70 Å resolution), the E335G catalytic mutant (2.95 Å resolution), a potential mercury derivative (2.15 Å resolution) and a selenomethionine derivative (3.90 Å resolution). These data are currently being used for detailed three-dimensional structure determination of the Xyn52B2 protein. PMID:25484225

  11. Artificial neural networks application for modeling of friction stir welding effects on mechanical properties of 7075-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Maleki, E.

    2015-12-01

    Friction stir welding (FSW) is a relatively new solid-state joining technique that is widely adopted in manufacturing and industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a very complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints makes it difficult to develop an overall governing equations system for theoretical behavior analyse of the friction stir welded joints. Weld quality is predominantly affected by welding effective parameters, and the experiments are often time consuming and costly. On the other hand, employing artificial intelligence (AI) systems such as artificial neural networks (ANNs) as an efficient approach to solve the science and engineering problems is considerable. In present study modeling of FSW effective parameters by ANNs is investigated. To train the networks, experimental test results on thirty AA-7075-T6 specimens are considered, and the networks are developed based on back propagation (BP) algorithm. ANNs testing are carried out using different experimental data that they are not used during networks training. In this paper, rotational speed of tool, welding speed, axial force, shoulder diameter, pin diameter and tool hardness are regarded as inputs of the ANNs. Yield strength, tensile strength, notch-tensile strength and hardness of welding zone are gathered as outputs of neural networks. According to the obtained results, predicted values for the hardness of welding zone, yield strength, tensile strength and notch-tensile strength have the least mean relative error (MRE), respectively. Comparison of the predicted and the experimental results confirms that the networks are adjusted carefully, and the ANN can be used for modeling of FSW effective parameters.

  12. Ballistic limit of 6061 T6 aluminum and threat to surface coatings for use with orbiting space station space suit materials

    NASA Technical Reports Server (NTRS)

    Fish, D.

    1986-01-01

    In recent years orbiting satellites, spent components, collisions and explosions have populated the near earth orbit with debris potentially more hazardous than the average meteoroid debris. This new debris has an average density of aluminum (2.78 g/cc) and an average encounter velocity of 10 km/sec. The space station will require many hours of work in this environment and there is concern over hazard to the assembly personnel. A proposed hard suit design utilizes 6061-T6 Aluminum for most of its exposed area. The aluminum surface will be treated for thermal and radiation control. The basic thickness of this suit will be on the order of 1.78 mm (0.070 inches). The selection of 6061-T6 Aluminum for space suits for use on the space station would appear to be worthwhile. The relatively ductile behavior of 6061-T6 aluminum is better than a choice of a more brittle material.

  13. Novel Gene Clusters and Metabolic Pathway Involved in 3,5,6-Trichloro-2-Pyridinol Degradation by Ralstonia sp. Strain T6

    PubMed Central

    Li, Jingquan; Huang, Yan; Hou, Ying; Li, Xiangmin; Cao, Hui

    2013-01-01

    3,5,6-Trichloro-2-pyridinol (TCP) is a widespread pollutant. Some bacteria and fungi have been reported to degrade TCP, but the gene clusters responsible for TCP biodegradation have not been characterized. In this study, a fragment of the reduced flavin adenine dinucleotide (FADH2)-dependent monooxygenase gene tcpA was amplified from the genomic DNA of Ralstonia sp. strain T6 with degenerate primers. The tcpA disruption mutant strain T6-ΔtcpA could not degrade TCP but could degrade the green intermediate metabolite 3,6-dihydroxypyridine-2,5-dione (DHPD), which was generated during TCP biodegradation by strain T6. The flanking sequences of tcpA were obtained by self-formed adaptor PCR. tcpRXA genes constitute a gene cluster. TcpR and TcpX are closely related to the LysR family transcriptional regulator and flavin reductase, respectively. T6-ΔtcpA-com, the complementation strain for the mutant strain T6-ΔtcpA, recovered the ability to degrade TCP, and the strain Escherichia coli DH10B-tcpRXA, which expressed the tcpRXA gene cluster, had the ability to transform TCP to DHPD, indicating that tcpA is a key gene in the initial step of TCP degradation and that TcpA dechlorinates TCP to DHPD. A library of DHPD degradation-deficient mutants of strain T6 was obtained by random transposon mutagenesis. The fragments flanking the Mariner transposon were amplified and sequenced, and the dhpRIJK gene cluster was cloned. DhpJ could transform DHPD to yield an intermediate product, 5-amino-2,4,5-trioxopentanoic acid (ATOPA), which was further degraded by DhpI. DhpR and DhpK are closely related to the AraC family transcriptional regulator and the MFS family transporter, respectively. PMID:24056464

  14. H-NS binding to evpB and evpC and repressing T6SS expression in fish pathogen Edwardsiella piscicida.

    PubMed

    Cui, Shilei; Xiao, Jingfan; Wang, Qiyao; Zhang, Yuanxing

    2016-09-01

    Edwardsiella piscicida is an important causative agent of hemorrhagic septicemia in fish and infects both cultured and wild fish species. Type VI secretion system (T6SS) was proved to play important roles in pathogenesis of E. piscicida. In this study, it was demonstrated that the expression of T6SS genes evpB and evpC was under control of the global regulator H-NS in E. piscicida and the transcriptional level of evpB and evpC was significantly down-regulated by H-NS. Compared to the wild type, the transcriptional levels of evpB and evpC were up-regulated in hns null mutant, while down-regulated in hns overexpression strain. The results of EMSA and DNase I footprinting revealed that H-NS protein directly bound to upstream region of evpC at multiple sites. A high-affinity motif with a 9-nucleotide sequence 5'-ATATAAAAT-3' was defined for H-NS preferential recognition based on the feature of the binding sites. These results indicated that H-NS acted cooperatively to form extended nucleoprotein filaments on target DNA. Site-directed mutagenesis of H-NS further showed that R86 played an essential role in T6SS gene binding. These findings highlighted the mechanisms underlying the complex regulation network of T6SS by H-NS in E. piscicida. PMID:27125651

  15. t(6;9)(p22;q34)/DEK-NUP214-rearranged pediatric myeloid leukemia: an international study of 62 patients

    PubMed Central

    Sandahl, Julie Damgaard; Coenen, Eva A.; Forestier, Erik; Harbott, Jochen; Johansson, Bertil; Kerndrup, Gitte; Adachi, Souichi; Auvrignon, Anne; Beverloo, H. Berna; Cayuela, Jean-Michel; Chilton, Lucy; Fornerod, Maarten; de Haas, Valérie; Harrison, Christine J.; Inaba, Hiroto; Kaspers, Gertjan J.L.; Liang, Der-Cherng; Locatelli, Franco; Masetti, Riccardo; Perot, Christine; Raimondi, Susana C.; Reinhardt, Katarina; Tomizawa, Daisuke; von Neuhoff, Nils; Zecca, Marco; Zwaan, C. Michel; van den Heuvel-Eibrink, Marry M.; Hasle, Henrik

    2014-01-01

    Acute myeloid leukemia with t(6;9)(p22;q34) is listed as a distinct entity in the 2008 World Health Organization classification, but little is known about the clinical implications of t(6;9)-positive myeloid leukemia in children. This international multicenter study presents the clinical and genetic characteristics of 62 pediatric patients with t(6;9)/DEK-NUP214-rearranged myeloid leukemia; 54 diagnosed as having acute myeloid leukemia, representing <1% of all childhood acute myeloid leukemia, and eight as having myelodysplastic syndrome. The t(6;9)/DEK-NUP214 was associated with relatively late onset (median age 10.4 years), male predominance (sex ratio 1.7), French-American-British M2 classification (54%), myelodysplasia (100%), and FLT3-ITD (42%). Outcome was substantially better than previously reported with a 5-year event-free survival of 32%, 5-year overall survival of 53%, and a 5-year cumulative incidence of relapse of 57%. Hematopoietic stem cell transplantation in first complete remission improved the 5-year event-free survival compared with chemotherapy alone (68% versus 18%; P<0.01) but not the overall survival (68% versus 54%; P=0.48). The presence of FLT3-ITD had a non-significant negative effect on 5-year overall survival compared with non-mutated cases (22% versus 62%; P=0.13). Gene expression profiling showed a unique signature characterized by significantly higher expression of EYA3, SESN1, PRDM2/RIZ, and HIST2H4 genes. In conclusion, t(6;9)/DEK-NUP214 represents a unique subtype of acute myeloid leukemia with a high risk of relapse, high frequency of FLT3-ITD, and a specific gene expression signature. PMID:24441146

  16. Full Field Measurement of The Dynamic Response of AA6061-T6 Aluminum Alloy under High Strain Rate Compression and Torsion Loads

    NASA Astrophysics Data System (ADS)

    Odoh, Daniel Oghenekewhe Oluwatobi

    The dynamic response of AA6061-T6 aluminum alloy under high strain rate loading in compression and torsion loading conditions was studied using the split Hopkinson pressure bar, the Kolsky torsion bar, and the high speed digital image correlation system. AA6061-T6 alloy, the most widely used in the AA6000 series, is a multi-purpose Al-Mg-Si-Cu alloy containing about 0.4 % wt. of Cu and other alloying additives. The properties of AA6061-T6 aluminum alloy including medium to high strength, good fracture toughness, and high corrosion resistance make it to find application in high performance structures such as the automotive parts, panels, and armored carriers. In this work, the effect of strain rate during dynamic test on formation of adiabatic shear bands in AA6061-T6 alloy was investigated. A post deformation analysis of the tested specimen was performed in order to determine the damage evolution and strain localization along the narrow adiabatic shear bands within the specimen. The formation of an adiabatic shear band in the aluminum alloy tested was found to depend on the strain rate at which the test was conducted. Stress, strain, and strain rate data obtained from the elastic waves in the compression and torsion bar tests were also compared with those obtained using the high speed digital cameras. Results show good agreement between both measurement techniques with the 3D digital image correlation technique giving a slightly lower result. Scanning and electron microscopy results show that both deformed and transformed bands can be formed in AA6061-T6 alloy during dynamic loading. The type of adiabatic shear band formed depends on the strain rate at which test was performed.

  17. Structure-specificity relationships in Abp, a GH27 β-L-arabinopyranosidase from Geobacillus stearothermophilus T6.

    PubMed

    Lansky, Shifra; Salama, Rachel; Solomon, Hodaya V; Feinberg, Hadar; Belrhali, Hassan; Shoham, Yuval; Shoham, Gil

    2014-11-01

    L-Arabinose sugar residues are relatively abundant in plants and are found mainly in arabinan polysaccharides and in other arabinose-containing polysaccharides such as arabinoxylans and pectic arabinogalactans. The majority of the arabinose units in plants are present in the furanose form and only a small fraction of them are present in the pyranose form. The L-arabinan-utilization system in Geobacillus stearothermophilus T6, a Gram-positive thermophilic soil bacterium, has recently been characterized, and one of the key enzymes was found to be an intracellular β-L-arabinopyranosidase (Abp). Abp, a GH27 enzyme, was shown to remove β-L-arabinopyranose residues from synthetic substrates and from the native substrates sugar beet arabinan and larch arabinogalactan. The Abp monomer is made up of 448 amino acids, and based on sequence homology it was suggested that Asp197 is the catalytic nucleophile and Asp255 is the catalytic acid/base. In the current study, the detailed three-dimensional structure of wild-type Abp (at 2.28 Å resolution) and its catalytic mutant Abp-D197A with (at 2.20 Å resolution) and without (at 2.30 Å resolution) a bound L-arabinose product are reported as determined by X-ray crystallography. These structures demonstrate that the three-dimensional structure of the Abp monomer correlates with the general fold observed for GH27 proteins, consisting of two main domains: an N-terminal TIM-barrel domain and a C-terminal all-β domain. The two catalytic residues are located in the TIM-barrel domain, such that their carboxylic functional groups are about 5.9 Å from each other, consistent with a retaining mechanism. An isoleucine residue (Ile67) located at a key position in the active site is shown to play a critical role in the substrate specificity of Abp, providing a structural basis for the high preference of the enzyme towards arabinopyranoside over galactopyranoside substrates. The crystal structure demonstrates that Abp is a tetramer

  18. Tensile Properties of 7075-T6 and 2024-T3 Aluminum-alloy Sheet Heated at Uniform Temperature Rates Under Constant Load

    NASA Technical Reports Server (NTRS)

    Heimerl, George J; Inge, John E

    1955-01-01

    Results are presented of tests to determine the effect of heating at uniform temperature rates from 0.2 degrees to 100 degrees F. per second on the tensile properties of 7075-T6 d(75s-T6) and 2024-T3 (24s-T3) aluminum-alloy sheet under constant-load conditions. Yield and rupture stresses, obtained under rapid-heating conditions, are compared with results of elevated-temperature stress-strain tests for 1/2-hour exposure. Master yield-and-rupture-stress curves based on linear temperature-rate parameter are presented. Yield and rupture stresses and temperatures may be predicted by means of master curves and the parameter.

  19. A mouse 3T6 fibroblast cell culture model for the study of normal and protein-engineered collagen synthesis and deposition into the extracellular matrix.

    PubMed

    Lamandé, S R; Bateman, J F

    1993-07-01

    Mouse 3T6 fibroblasts deposited an organized collagenous extracellular matrix during long-term culture in the presence of ascorbic acid. The matrix produced by the cells had a similar distribution of collagen types as the mouse dermal matrix, comprising predominantly type I with smaller amounts of types III and V collagens. By day 8 of culture more than 70% of the collagen in the 3T6 matrix was involved in covalent crosslinkages and required pepsin digestion for extraction. Incorporation of NaB3H4 into reducible crosslinks and aldehydes directly demonstrated the involvement of the alpha 1 (I)CB6 and alpha 2(I)CB3.5 in crosslinks. The pattern of reducible crosslinks in the in vitro 3T6 matrix was similar to that in mouse skin suggesting a comparable fibril organization. Processing of procollagen to collagen occurred efficiently throughout the culture period and the rate of collagen production was unaltered during 15 days of culture, indicating that the development of a collagenous matrix does not directly play a role in procollagen processing or biosynthetic regulation. The existence of a preformed matrix did however, increase the efficiency with which newly synthesised collagen was incorporated into the pericellular matrix. At day 0, when there was no measurable matrix present, 29% of the collagen synthesised was deposited, while by day 15, 88% of the collagen was laid down in the matrix. The development of this 3T6 culture system, where collagen is efficiently incorporated into an organized extracellular matrix, will facilitate detailed studies on matrix organization and regulation and provide a system in which protein-engineered mutant collagens can be expressed to determine their effects on the production of a functional extracellular matrix. PMID:8412990

  20. Wear and corrosion performance of two different tempers (T6 and T73) of AA7075 aluminium alloy after nitrogen implantation

    NASA Astrophysics Data System (ADS)

    Abreu, C. M.; Cristóbal, M. J.; Figueroa, R.; Pena, G.

    2015-02-01

    The present work reports the improvements in corrosion resistance and tribological properties achieved after Nitrogen ion implantation into aluminium alloy AA7075 subjected to two different tempers, T6 and T73. Nitrogen implantation at a nominal dose of 2 × 1017 ions/cm2 and at an accelerating voltage of 50 keV produced an increase of the surface hardness of the alloys up to a 130% in T6 samples and to 190% in T73 samples. The increase in hardness has a very positive effect on wear resistance as indicate the significant reduction of specific wear rate on both tempers (about -75% for T6 and -90% for T73 samples). Similarly, an improvement in corrosion properties of both tempers is confirmed by DC techniques, showing a decrease of the registered current density on potentiodynamic curves, and by the increase of impedance shown by AC techniques. This overall improvement in the alloy performance has been mainly attributed to the formation of a stoichiometric aluminium nitride layer (AlN), identified by XPS and GIXRD. The combination of EXCO immersion tests and electrochemical measurements allowed explaining the effect of AlN layer, which behave as a barrier delaying the onset of corrosion and slowing its progress. However, the implantation do not modified the corrosion morphology which seems to be determined mainly by the heat treating conditions. Thereby, in both tempers the localized attack starts at the intermetallic/matrix interface, but in T6 type specimens the progress of corrosion is clearly intergranular, while T73 specimens show the formation of clusters of small geometrical pits, probably related to the biggest MgZn2 strengthening precipitates.

  1. Direct-reading design charts for 75S-T6 aluminum-alloy flat compression panels having longitudinal extruded Z-section stiffeners

    NASA Technical Reports Server (NTRS)

    Hickman, William A; Dow, Norris F

    1951-01-01

    Direct-reading design charts are presented for 75S-T6 aluminum-alloy flat compression panels having longitudinal extruded Z-section stiffeners. These charts, which cover a wide range of proportions, make possible the direct determination of the stress and all panel dimensions required to carry a given intensity of loading with a given skin thickness and effective length of panel.

  2. Galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718 and graphite-epoxy composite material: Corrosion occurrence and prevention

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Higgins, R. H.

    1983-01-01

    The effects of galvanic coupling between D6AC steel, 6061-T6 aluminum, Inconel 718, and graphite-epoxy composite material (G/E) in 3.5% NaCl were studied. Measurements of corrosion potentials, galvanic currents and corrosion rates of the bare metals using weight-loss methods served to establish the need for corrosion protection in cases where D6AC steel and 6061-T6 aluminum are galvanically coupled to G/E in salt water while Inconel 718 was shown to be compatible with G/E. Six tests were made to study corrosion protective methods for eliminating galvanic corrosion in the cases of D6AC steel and 6061-T6 aluminum coupled to G/E. These results indicate that, when the G/E is completely coated with paint or a paint/polyurethane resin combination, satisfactory protection of the D6AC steel is achieved with either a coat of zinc-rich primer or a primer/topcoat combination. Likewise, satisfactory corrosion protection of the aluminum is achieved by coating it with an epoxy coating system.

  3. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651, and titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Terrell, J.

    1973-01-01

    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651 and titanium 6Al-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 7) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity), and demineralized distilled water. Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, titanium stressed specimens showed no reactions to its environment. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 and aluminum 2014-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl), while aluminum 2219-T87 seem to resist stress corrosion cracking in sodium chloride at three levels of stress (25%, 50%, and 75% Y.S.). In organic fluids of methyl, ethyl, and iso-propyl alcohol, 2014-T6 and 7075-T651 did not fail by SCC; but 2014-T651 was susceptible to SCC in methly alcohol, but resistant in ethyl alcohol, iso-propyl alcohol and demineralized distilled water.

  4. Expression of murine leukemia viruses in RFM mice with host versus graft disease after perinatal inoculation of (T6 X RFM)F1 lymphohemopoietic cells.

    PubMed Central

    Cross, S S; Brede, G; Tucker, H S; Maloney, M; Montour, J L; Hard, R C

    1983-01-01

    Host versus graft disease is the fatal syndrome of altered immunity that follows the perinatal inoculation of related F1 hybrid spleen cells to susceptible strains of inbred mice. The allogenic reaction results in severe depletion of T-lymphocytes, but causes hyperplasia and hypersecretion of B-cells. Among the long-term survivors of acute host versus graft reactions, there is a high incidence of nonthymic lymphomas associated with ecotropic murine leukemia virus that may be of donor F1 origin. The present studies were done to determine whether ecotropic murine leukemia virus played any role in the pathogenesis of acute host versus graft disease in RFM mice perinatally inoculated with (T6 X RFM)F1 spleen cells. In RFM/(T6 X RFM)F1 chimeras, N-tropic murine leukemia virus can be detected as early as 3 days. The progression of the disease was accompanied by increasing viral expression. The inoculation of N-tropic virus of F1 donor origin into RFM neonates failed to induce disease, although the virus proliferated. Detection of progressively rising titers of antibody to murine leukemia virus linked the virus to the development of hyperimmunoglobulinemia by virtue of its ability to serve as a replicating source of antigens. These and other studies provided evidence that the seemingly paradoxical appearance of hyperimmunoglobulinemia in T-cell-deficient mice with the host versus graft syndrome is due, at least in part, to the stimulation of presensitized F1 donor B-cells, which are not destroyed in the allogenic reaction, as are the T-cells. Another unusual finding was the detection of polytropic murine leukemia virus in 25-day-old RFM/(T6 X RFM)F1 chimeras. It is suggested that the allogenic host versus graft reaction favored the formation of recombinants. PMID:6135664

  5. Detection and serogroup differentiation of Salmonella spp. in food within 30 hours by enrichment-immunoassay with a T6 monoclonal antibody capture enzyme-linked immunosorbent assay.

    PubMed Central

    Ng, S P; Tsui, C O; Roberts, D; Chau, P Y; Ng, M H

    1996-01-01

    We previously described an antigen capture enzyme-linked immunosorbent assay which makes use of monoclonal antibody T6, which recognizes an epitope on the outer core polysaccharide of Salmonella lipopolysaccharide molecules that is common to almost all Salmonella serovars. In this paper, we show that this assay can detect between 10(5) and 10(7) Salmonella cells per ml even in the presence of excess Escherichia coli. A total of 153 of 154 (99%) serogroup A to E strains and 51 of 78 (71%) serogroup F to 67 strains were reactive as determined by this assay. This corresponds to a detection rate of approximately 98% of all salmonellae known to affect humans. None of the 65 strains of non-Salmonella bacteria tested positive. Taking advantage of the O-factor polysaccharides also present on the antigen captured by the immobilized T6 antibody, we showed that 136 of 154 Salmonella serogroup A to E strains (88%) were correctly differentiated according to their serogroups by use of enzyme conjugates of a panel of O-factor-specific monoclonal antibodies. We evaluated this assay for the detection and serogroup differentiation of salmonellae directly from enrichment cultures of simulated food, eggs, pork, and infant formula milk. All 26 samples which had been contaminated with Salmonella spp. were detected by T6 (100% sensitivity), with only one false-positive result from 101 samples not contaminated by Salmonella spp. (99% specificity). The detection time was substantially reduced to between 17 and 29 h, depending on the enrichment methods used. Since there were no false-negative results, we concluded that this enrichment-immunoassay method can afford rapid screening for Salmonella spp. in food samples. PMID:8779567

  6. Quasi-steady state principle and in-situ real-time investigation of transient strains in 6061-T6 Al alloy using neutron diffraction

    SciTech Connect

    Woo, Wan Chuck; Brown, D. W.; Choo, Hahn; Clausen, B; David, Stan A; Feng, Zhili; Hubbard, Camden R; Wang, Xun-Li

    2007-01-01

    Neutron diffraction research has been limited to the "static" behavior of materials since the number of collected neutrons is insufficient to reach the adequate neutron counts in rapid changes of material state. In order to achieve the desired precision for the study of the transient material behavior, we propose an in-situ neutron-diffraction measurement method based on the quasi-steady state (QSS) phenomenon. The QSS principle was applied for the measurement of transient lattice spacing changes in a 6061-T6 aluminum alloy plate during thermo-mechanical processing.

  7. Production, crystallization and X-ray diffraction analysis of a complex between a fragment of the TssM T6SS protein and a camelid nanobody.

    PubMed

    Nguyen, Van Son; Spinelli, Silvia; Desmyter, Aline; Le, Thi Thu Hang; Kellenberger, Christine; Cascales, Eric; Cambillau, Christian; Roussel, Alain

    2015-03-01

    The type VI secretion system (T6SS) is a machine evolved by Gram-negative bacteria to deliver toxin effectors into target bacterial or eukaryotic cells. The T6SS is functionally and structurally similar to the contractile tail of the Myoviridae family of bacteriophages and can be viewed as a syringe anchored to the bacterial membrane by a transenvelope complex. The membrane complex is composed of three proteins: the TssM and TssL inner membrane components and the TssJ outer membrane lipoprotein. The TssM protein is central as it interacts with both TssL and TssJ, therefore linking the membranes. Using controlled trypsinolysis, a 32.4 kDa C-terminal fragment of enteroaggregative Escherichia coli TssM (TssM32Ct) was purified. A nanobody obtained from llama immunization, nb25, exhibited subnanomolar affinity for TssM32Ct. Crystals of the TssM32Ct-nb25 complex were obtained and diffracted to 1.9 Å resolution. The crystals belonged to space group P64, with unit-cell parameters a = b = 95.23, c = 172.95 Å. Molecular replacement with a model nanobody indicated the presence of a dimer of TssM32Ct-nb25 in the asymmetric unit. PMID:25760699

  8. Lineage switch with t(6;11)(q27;q23) from T-cell lymphoblastic lymphoma to acute monoblastic leukemia at relapse.

    PubMed

    Higuchi, Yusuke; Tokunaga, Kenji; Watanabe, Yuko; Kawakita, Toshiro; Harada, Naoko; Yamaguchi, Shunichiro; Nosaka, Kisato; Mitsuya, Hiroaki; Asou, Norio

    2016-06-01

    We present a patient with T-cell lymphoblastic lymphoma (T-LBL) harboring t(6;11)(q27;q23) that converted to acute monoblastic leukemia at relapse. A 27-year-old man developed T-LBL with a mediastinal mass. He exhibited several recurrences in the central nervous system and marrow. A fifth relapse occurred in the marrow, with 42.8% blasts with CD4, CD5, CD7, CD10, CD33, CD34, HLA-DR and cytoplasmic (cy) CD3. While achieving complete remission with nelarabine, sixth relapse occurred in the marrow with 6.8% blasts, which had characteristics of monoblastic features, 2 months later. Marrow blasts were positive for myeloperoxidase, CD4, CD33, CD56, CD64, and HLA-DR, but were negative for cyCD3, CD5, CD7, CD10, and CD34. Marrow cells at both the 5th lymphoid and 6th myeloid relapses had t(6;11)(q27;q23) and the same MLL-MLLT4 fusion transcript. In addition, the MLL-MLLT4 fusion sequences documented in the initial mediastinal cells were the same as seen in peripheral blood cells at the 6th relapse. The patient continues 7th remission after one course of gemtuzumab ozogamicin therapy followed by cord blood transplantation for more than 3 years. Sequential phenotypic and cytogenetic studies may yield valuable insights into the mechanism of leukemic recurrence and possible implications for treatment selection. PMID:27268298

  9. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, aluminum 7075-T651, and titanium 6Al-4V

    NASA Technical Reports Server (NTRS)

    Terrell, J.

    1972-01-01

    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 7075-T651 and titanium 6A1-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 6) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity). Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, a similar observation was not noted for titanium stressed specimens. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl); while they (both alloys) seem to resist stress corrosion cracking in methyl alcohol, ethyl alcohol, iso-propyl alcohol, and demineralized distilled water. Titanium 6A1-4V showed some evidence of susceptibility to SCC in methanol, while no such susceptibility was exhibited in ethanol, iso-propyl alcohol and demineralized distilled water.

  10. Microscopic Observation of the Side Surface of Dynamically-Tensile-Fractured 6061-T6 and 2219-T87 Aluminum Alloys with Pre-Fatigue

    NASA Astrophysics Data System (ADS)

    Itabashi, Masaaki; Nakajima, Shigeru; Fukuda, Hiroshi

    After unexpected failure of metallic structure, microscopic investigation will be performed. Generally, such an investigation is limited to search striation pattern with a SEM (scanning electron microscope). But, when the cause of the failure was not severe repeated stress, this investigation is ineffective. In this paper, new microscopic observation technique is proposed to detect low cycle fatigue-impact tensile loading history. Al alloys, 6061-T6 and 2219-T87, were fractured in dynamic tension, after severe pre-fatigue. The side surface of the fractured specimens was observed with a SEM. Neighboring fractured surface, many opened cracks on the side surface have been generated. For each specimen, the number of the cracks was counted together with information of individual sizes and geometric features. For 6061-T6 alloy specimen with the pre-fatigue, the number of the cracks is greater than that for the specimen without the pre-fatigue. For 2219-T87 alloy, the same tendency can be found after a certain screening of the crack counting. Therefore, the crack counting technique may be useful to detect the existence of the pre-fatigue from the dynamically fractured specimen surface.

  11. Radio Flaring from the T6 Dwarf WISEPC J112254.73+255021.5 with a Possible Ultra-short Periodicity

    NASA Astrophysics Data System (ADS)

    Route, Matthew; Wolszczan, Alexander

    2016-04-01

    We present new results from a continuing 5 GHz search for flaring radio emission from a sample of L and T brown dwarfs, conducted with the 305 m Arecibo radio telescope. In addition to the previously reported flaring from the T6.5 dwarf 2MASS J10475385+212423, we have detected and confirmed circularly polarized flares from another T6 dwarf, WISEPC J112254.73+255021.5. Although the flares are sporadic, they appear to occur at a stable period of 0.288 hr. Given the current constraints, periods equal to its second and third subharmonic cannot be ruled out. The stability of this period over the eight-month timespan of observations indicates that, if real, it likely reflects the star’s rapid rotation. If confirmed, any of the three inferred periodicities would be much shorter than the shortest, 1.41 hr, rotation period of a brown dwarf measured so far. This finding would place a new observational constraint on the angular momentum evolution and rotational stability of substellar objects. The detection of radio emission from the sixth ∼1000 K dwarf further demonstrates that the coolest brown dwarfs and, possibly, young giant planets, can be efficiently investigated using radio observations at centimeter wavelengths as a tool.

  12. Quantum chemical study of the enzymatic repair of T(6-4)C/C(6-4)T UV-photolesions by DNA photolyases.

    PubMed

    Faraji, Shirin; Wirz, Lukas; Dreuw, Andreas

    2013-08-26

    Several strategies have evolved to repair one of the abundant UV radiation-induced damages caused to DNA, namely the mutagenic pyrimidine (6-4) pyrimidone photolesions. DNA (6-4)-photolyases are enzymes repairing these lesions by a photoinitiated electron transfer. An important aspect of a possible repair mechanism is its generality and transferability to different (6-4) lesions. Therefore, previously suggested mechanisms for the repair of the T(6-4)T lesion are here transferred to the T(6-4)C and C(6-4)T lesions and investigated theoretically using quantum chemical methods. Despite the different functional groups of the pyrimidine bases involved, a general valid molecular mechanism was identified, in which the initial step is an electron transfer coupled to a proton transfer from the protonated HIS365 to the N3(') nitrogen of the 3(') pyrimidine, followed by an intramolecular OH/NH2 transfer in one concerted step, which does not require an oxetane/azetidine or isolated water/ammonia intermediate. PMID:23821498

  13. Modeling of the Effect of Temperature, Frequency, and Phase Transformations on the Viscoelastic Properties of AA 7075-T6 and AA 2024-T3 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Rojas, Jose I.; Crespo, Daniel

    2012-12-01

    The viscoelastic response of commercial aluminum alloys 7075-T6 and 2024-T3 as a function of temperature is presented. Experimental data are obtained with a dynamic-mechanical analyzer (DMA) at different loading frequencies and compared with the available transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) data. The effect of successive microstructural transformations (particle precipitation and redissolution) is revealed. An analytical model is developed, which fits the mechanical response up to 573 K (300 °C). The model takes into account the concentration of Guinier-Preston Zones (GPZ) and metastable precipitates ( η' in AA 7075-T6 and θ'/S' in AA 2024-T3), allowing us to determine the kinetic parameters of these transformations. The activation energies were previously obtained by several authors from DSC measurements and other techniques, showing considerable dispersion. The presented data, obtained with a completely different technique, allow us to reduce the uncertainty on these data and show the potential of DMA measurements in the study of microstructural transformations.

  14. Cryptolepine derivative-6h inhibits liver fibrosis in TGF-β1-induced HSC-T6 cells by targeting the Shh pathway.

    PubMed

    He, Ying-Hua; Li, Zeng; Ni, Ming-Ming; Zhang, Xing-Yan; Li, Ming-Fang; Meng, Xiao-Ming; Huang, Cheng; Li, Jun

    2016-09-01

    Liver fibrosis is a worldwide problem with a significant morbidity and mortality. Cryptolepis sanguinolenta (family Periplocaceae) is widely used in West African countries for the treatment of malaria, as well as for some other diseases. However, the role of C. sanguinolenta in hepatic fibrosis is still unknown. It has been reported that Methyl-CpG binding protein 2 (MeCP2) had a high expression in liver fibrosis and played a central role in its pathobiology. Interestingly, we found that a cryptolepine derivative (HZ-6h) could inhibit liver fibrosis by reducing MeCP2 expression, as evidenced by the dramatic downregulation of α-smooth muscle actin (α-SMA) and type I collagen alpha-1 (Col1α1) in protein levels in vitro. Meanwhile, we also found that HZ-6h could reduce the cell viability and promote apoptosis of hepatic stellate cells (HSCs) treated with transforming growth factor beta 1(TGF-β1). Then, we investigated the potential molecular mechanisms and found that HZ-6h blocked Shh signaling in HSC-T6 cells, resulting in the decreased protein expression of Patched-1 (PTCH-1), Sonic hedgehog (Shh), and glioma-associated oncogene homolog 1 (GLI1). In short, these results indicate that HZ-6h inhibits liver fibrosis by downregulating MeCP2 through the Shh pathway in TGF-β1-induced HSC-T6 cells. PMID:27295431

  15. Effects of aging treatment and heat input on the microstructures and mechanical properties of TIG-welded 6061-T6 alloy joints

    NASA Astrophysics Data System (ADS)

    Peng, Dong; Shen, Jun; Tang, Qin; Wu, Cui-ping; Zhou, Yan-bing

    2013-03-01

    Aging treatment and various heat input conditions were adopted to investigate the microstructural evolution and mechanical properties of TIG welded 6061-T6 alloy joints by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone (HAZ) increases and grains in the fusion zone (FZ) coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175°C for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.

  16. Investigation of Microstructure and Microhardness in Self-Reacting Friction Stir Welded AA2014-T6 and AA2219-T87

    NASA Technical Reports Server (NTRS)

    Horton, K. Renee; McGill, Preston; Barkey, Mark

    2011-01-01

    Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. This work reports on the microstructure and microhardness of SR-FSW between two dissimilar aluminum alloys. Specifically, the study examines the cross section of the weld joint formed between an AA2014-T6 plate on the advancing side and an AA2219-T87 plate on the retreating side. The microstructural analysis shows an irregularly displaced weld seam from the advancing side past the thermo-mechanical affected zone (TMAZ) into the weld nugget region. There are sharp variations in the microhardness across the weld. These variations are described in the paper and mechanisms for their formation are discussed.

  17. The young's modulus of 1018 steel and 67061-T6 aluminum measured from quasi-static to elastic precursor strain-rates

    SciTech Connect

    Rae, Philip J; Trujillo, Carl; Lovato, Manuel

    2009-01-01

    The assumption that Young's modulus is strain-rate invariant is tested for 6061-T6 aluminium alloy and 1018 steel over 10 decades of strain-rate. For the same billets of material, 3 quasi-static strain-rates are investigated with foil strain gauges at room temperature. The ultrasonic sound speeds are measured and used to calculate the moduli at approximately 10{sup 4} s{sup -1}. Finally, ID plate impact is used to generate an elastic pre-cursor in the alloys at a strain-rate of approximately 10{sup 6} s{sup -1} from which the longitudinal sound speed may be obtained. It is found that indeed the Young's modulus is strain-rate independent within the experimental accuracy.

  18. Influences of post weld heat treatment on tensile strength and microstructure characteristics of friction stir welded butt joints of AA2014-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Rajendran, C.; Srinivasan, K.; Balasubramanian, V.; Balaji, H.; Selvaraj, P.

    2016-08-01

    Friction stir welded (FSWed) joints of aluminum alloys exhibited a hardness drop in both the advancing side (AS) and retreating side (RS) of the thermo-mechanically affected zone (TMAZ) due to the thermal cycle involved in the FSW process. In this investigation, an attempt has been made to overcome this problem by post weld heat treatment (PWHT) methods. FSW butt (FSWB) joints of Al-Cu (AA2014-T6) alloy were PWHT by two methods such as simple artificial aging (AA) and solution treatment followed by artificial aging (STA). Of these two treatments, STA was found to be more beneficial than the simple aging treatment to improve the tensile properties of the FSW joints of AA2014 aluminum alloy.

  19. Craniosynostosis and hemizygosity for D7S135 caused by a de novo and apparently balanced t(6;7) translocation

    SciTech Connect

    Tsuji, Kazushiro; Narahara, Kouji; Kikkawa, Kiyoshi; Murakami, Masae; Yokoyama, Yuji; Ninomiya, Shinsuke; Seino, Yoshiki

    1994-01-01

    Craniosynostosis (CRS) is frequently seen in the del(7p) syndrome, and the gene for this cranial anomaly (CRS1) has been assigned to 7p21. The authors present a 3-year-old boy with CRS involving the sagittal and coronal sutures, who had a de novo and apparently balanced translocation, t(6;7)(q16.2;p15.3). Southern blot analysis of several loci on 7p14{yields}pter showed that the patient was heterozygous for HOX1I and IL6, possibly homozygous for D7S149, but hemizygous for D7S135 with a loss of the paternal allele. These findings suggest the localization of a candidate gene for CRS1 to be on 7p15.3 in the close proximity to the D7S135 locus. 19 refs., 5 figs., 2 tabs.

  20. A transmission electron microscopy study of constituent-particle-induced corrosion in 7075-T6 and 2024-T3 aluminum alloys

    SciTech Connect

    Wei, R.P.; Liao, C.M.; Gao, M.

    1998-04-01

    To better understand particle-induced pitting corrosion in aluminum alloys, thin foil specimens of 7075-T6 and 2024-T3 aluminum alloys, with identified constituent particles, were immersed in aerated 0.5M NaCl solution and then examined by transmission electron microscopy (TEM). The results clearly showed matrix dissolution around the iron- and manganese-containing particles (such as Al{sub 23}CuFe{sub 4}), as well as the Al{sub 2}Cu particles. While Al{sub 2}CuMg particles tended to dissolve relative to the matrix, limited local dissolution of the matrix was also observed around these particles. These results are consistent with scanning electron microscopy (SEM) observations of pitting corrosion and are discussed in terms of the electrochemical characteristics of the particles and the matrix.

  1. Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

    SciTech Connect

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; Miles, Michael; Song, Guang-Ling; Wang, Yanli; Feng, Zhili

    2014-12-30

    We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly prepared joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.

  2. Effects of Cyclic Loading on Mechanical Behavior of 24S-T4 and 75S-T6 Aluminum Alloys and SAE 4130 Steel

    NASA Technical Reports Server (NTRS)

    Macgregor, C W; Grossman, N

    1952-01-01

    An investigation was conducted to determine the effects of cyclic loading on the mechanical behavior of 24S-T4 and 75S-T6 aluminum alloys and SAE 4130 steel. Specimens of the three materials were subjected to various numbers of prior fatigue cycles both below and above the fatigue limits. Special slow-bend tests were employed to show the effects of prior cycles of fatigue stressing on the transition temperature to brittle fracture for SAE 4130 steel and on the energy-absorption capacity of the aluminum alloys. Micrographic studies were made to observe and measure crack formation and propagation and additional special tests were conducted to supplement the results of the slow-bend tests. These included Charpy impact tests, mirohardness surveys, tension tests, and fretting-corrosion studies.

  3. In-situ Time-Resolved Neutron Diffraction Measurements of Microstructure Variations during Friction Stir Welding in a 6061-T6 Aluminum Alloy

    SciTech Connect

    Woo, Wan Chuck; Wang, Xun-Li; Ungar, Prof Tomas; Feng, Zhili; David, Stan A; Clausen, B; Hubbard, Camden R

    2008-01-01

    The microstructure change is one of the most important research areas in the friction stir welding (FSW). However, direct observation of microstructure changes during FSW has been extremely challenging because many measurement techniques are inapplicable. Recently developed in-situ time-resolved neutron diffraction methodology, which drastically improves the temporal resolution of neutron diffraction, enables to observe the transient microstructure changes during FSW. We installed a portable FSW system in the Spectrometer for MAterials Research at Temperature and Stress (SMARTS) at Los Alamos Neutron Science Center and the FSW was made on 6.35mm-thickness 6061-T6 Al alloy plate. At the same time, the neutron beam was centered on the mid-plane of the Al plate at 8 mm from the tool center (underneath the tool shoulder) and the diffraction peak was continuously measured during welding. The peak broadening analysis has been performed using the Williamson-Hall Method. The result shows that the dislocation density of about 3.2 x 10^15 m-2 duing FSW, which is the significant increse compared to the before (4.5 x 10^14 m-2) and after (4.0 x 10^14 m-2) the FSW. The quantitatively analysis of the grain structure can provide an insight to understand the transient variation of the microstructure during FSW.

  4. Microstructure and mechanical properties of twin-wire arc sprayed Ni-Al composite coatings on 6061-T6 aluminum alloy sheet

    NASA Astrophysics Data System (ADS)

    Wang, Ji-xiao; Liu, Jing-shun; Zhang, Lun-yong; Sun, Jian-fei; Wang, Zhi-ping

    2014-05-01

    We have systematically studied the microstructure and mechanical properties of Ni-5wt%Al and Ni-20wt%Al composite coatings fabricated on 6061-T6 aluminum alloy sheet by twin-wire arc spraying under different experimental conditions. The abrasive wear behavior and interface diffusion behavior of the composite coatings were evaluated by dry/wet rubber wheel abrasive wear tests and heat treatment, respectively. Experimental results indicate that the composite coatings exhibit features of adhesive wear. Besides, the Vickers microhardness of NiAl and Ni3Al intermetallic compounds is relatively larger than that of the substrate, which is beneficial for enhancing the wear resistance. With the increase of annealing temperature and time, the interface diffusion area between the Ni-Al coating and the substrate gradually expands with the formation of NiAl3 and Ni2Al3 phases, and is controlled by diffusion of aluminum atoms. The grain growth exponent n of diffusion kinetics of the Ni-Al coating, calculated via a high-temperature diffusion model at 400, 480, and 550°C, is between 0.28 and 0.38. This satisfies the cubic law, which is consistent with the general theoretical relationship of high-temperature diffusion.

  5. Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

    DOE PAGESBeta

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; Miles, Michael; Song, Guang-Ling; Wang, Yanli; Feng, Zhili

    2014-12-30

    We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly preparedmore » joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.« less

  6. Effect of Welding Parameters on Microstructure, Thermal, and Mechanical Properties of Friction-Stir Welded Joints of AA7075-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Lotfi, Amir Hossein; Nourouzi, Salman

    2014-06-01

    A high-strength Al-Zn-Mg-Cu alloy AA7075-T6 was friction-stir welded with various process parameter combinations incorporating the design of the experiment to investigate the effect of welding parameters on the microstructure and mechanical properties. A three-factors, five-level central composition design (CCD) has been used to minimize the number of experimental conditions. The friction-stir welding parameters have significant influence on the heat input and temperature profile, which in turn regulates the microstructural and mechanical properties of the joints. The weld thermal cycles and transverse distribution of microhardness of the weld joints were measured, and the tensile properties were tested. The fracture surfaces of tensile specimens were observed by a scanning electron microscope (SEM), and the formation of friction-stir processing zone has been analyzed macroscopically. Also, an equation was derived to predict the final microhardness and tensile properties of the joints, and statistical tools are used to develop the relationships. The results show that the peak temperature during welding of all the joints was up to 713 K (440 °C), which indicates the key role of the tool shoulder diameter in deciding the maximum temperature. From this investigation, it was found that the joint fabricated at a rotational speed of 1050 rpm, welding speed of 100 mm/min, and shoulder diameter of 14 mm exhibited higher mechanical properties compared to the other fabricated joints.

  7. Effect of Porosity on the Fatigue Life of Cast AC4C-T6 Alloy for Lcd Glass Transfer Robot

    NASA Astrophysics Data System (ADS)

    Shim, Hee-Jin; Kim, Jung-Kyu

    Aluminium has good corrosion properties and a high strength to weight reduction which makes it favourable in many applications. The increased use of aluminium casting in the automotive industry does also imply that the need for design data for aluminium increases. Especially for castings, the influences of casting defects are always an issue. For this reason fatigue properties for as-cast sand and permanent mould specimens with different contents of porosity have been studied. The cast aluminium specimens of two different porosities were fatigue tested in cyclic axial test at R=-1. Prior to fatigue test specimens were examined by CT-scan and sorted into two quality groups depending on the porosity level. The aim of this work was to investigate the fatigue life for cast AC4C-T6 alloy with different amounts of inherent porosity. An additional aim was to predict the durability for cast components with defect constrained in a specified volume of components, by using a commercial program MSC. Fatigue.

  8. Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy

    PubMed Central

    Brooks, Emily K.; Tobias, Menachem E.; Yang, Shuying; Bone, Lawrence B.; Ehrensberger, Mark T.

    2015-01-01

    This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin) and outer layer resistance (Rout) were lower for samples without cells cultured on the surface at 3 days (Rin = 2.64 e4 Ω/cm2, Rout = 140 Ω/cm2) compared to 21 days (Rin = 3.60 e4 Ω/cm2, Rout = 287 Ω/cm2) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin = 1.88 e5 Ω/cm2, Rout = 1060 Ω/cm2) which was observed to increase over time (21 day, Rin = 2.99 e4 Ω/cm2, Rout = 287 Ω/cm2). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. PMID:25715925

  9. Design, fabrication and test of a hydrogen heat pipe. [extruding and grooving 6063-T6 aluminum tubes for cryogenic heat pipes

    NASA Technical Reports Server (NTRS)

    Alario, J.

    1979-01-01

    Re-entrant groove technology was extended to hydrogen heat pipes. Parametric analyses are presented which optimize the theoretical design while considering the limitations of state-of-the-art extrusion technology. The 6063-T6 aluminum extrusion is 14.6 mm OD with a wall thickness of 1.66 mm and contains 20 axial grooves which surround a central 9.3 mm diameter vapor core. Each axial groove is 0.775 mm diameter with a 0.33 mm opening. An excess vapor reservoir is provided at the evaporator to minimize the pressure containment hazard during ambient storage. Modifications to the basic re-entrant groove profile resulted in improved overall performance. While the maximum heat transport capacity decreased slightly to 103 w-m the static wicking height increased markedly to 4.5 cm. The heat pipe became operational between 20 and 30 K after a cooldown from 77 K without any difficulty. Steady state performance data taken over a 19 to 23 K temperature range indicated: (1) maximum heat transport capacity of 5.4 w-m; (2) static wicking height of 1.42 cm; and (3) overall heat pipe conductance of 1.7 watts/deg C.

  10. Rigid D6-branes on {{{{T^6}}} left/ {{left( {{Z_2} × {Z_{2M}} × Ω mathcal{R}} right)}} right.} with discrete torsion

    NASA Astrophysics Data System (ADS)

    Förste, Stefan; Honecker, Gabriele

    2011-01-01

    We give a complete classification of {{{{T^6}}} left/ {{left( {{mathbb{Z}_2} × {mathbb{Z}_{2M}} × Ω mathcal{R}} right)}} right.} orientifolds on factorisable tori and rigid D6-branes on them. The analysis includes the supersymmetry, RR tadpole cancellation and K-theory conditions and complete massless open and closed string spectrum (i.e. non-chiral as well as chiral) for fractional or rigid D6-branes for all inequivalent compactification lattices, without and with discrete torsion. We give examples for each orbifold background, which show that on {mathbb{Z}_2} × {mathbb{Z}_6} and {mathbb{Z}_2} × mathbb{Z}_6^' there exist completely rigid D6-branes despite the self-intersections of orbifold image cycles. This opens up a new avenue for improved Standard Model building. On the other hand, we show that Standard and GUT model building on the {mathbb{Z}_2} × {mathbb{Z}_4} background is ruled out by simple arguments.

  11. Renal cell carcinomas with t(6;11)(p21;q12) presenting with tubulocystic renal cell carcinoma-like features

    PubMed Central

    Rao, Qiu; Zhang, Xiu-Mei; Tu, Pin; Xia, Qiu-Yuan; Shen, Qin; Zhou, Xiao-Jun; Shi, Qun-Li

    2013-01-01

    In this study, we reported an additional genetically confirmed case of renal cell carcinomas (RCCs) with t(6;11)(p21;q12) showing an unusual histological pattern. Histologically, the tumor was entirely composed of small to intermediate sized tubules and cysts. The tubules and cysts were lined by a single layer of flat, hobnail, cuboidal to columnar epithelial cells. Most cells demonstrated abundant eosinophilic cytoplasm with regular, round or oval nuclei and some inconspicuous nucleoli. All these morphological features are suggestive of tubulocystic carcinoma of the kidney. However, the tumor demonstrated moderately (2+) or strongly (3+) positive staining for TFEB, Cathepsin K, Ksp-cadherin, and vimentin but negative for TFE3, CD10, HMB45, melan A, CKpan, and CK7. Using a recently developed TFEB split FISH assay, the presence of TFEB rearrangement was demonstrated. Our results support the clinical application of a TFEB break-apart FISH assay for diagnosis and confirmation of TFEB RCC and further expand the morphologic spectrum that may be present in these neoplasms, sometimes raising a challenging differential diagnosis with other renal tumors. PMID:23826432

  12. The Young's modulus of 1018 steel and 6061-T6 aluminum measured from quasi-static to elastic precursor strain-rates

    NASA Astrophysics Data System (ADS)

    Rae, Philip; Trujillo, Carl; Gray, Rusty

    2009-06-01

    It is commonly assumed in engineering and physics that the elastic moduli of metals is independent of strain-rate, but is a weak function of temperature. An extensive literature search however has failed to find any citable reference in which the Young's modulus of any pedigreed metal was measured over a wide variety of strain-rates. To rectify this, samples of pedigreed 1018 steel and 6061-T6 aluminum have been tested at strain-rates from 10-4 s-1 to 10^6 s-1. Low strain-rate data (10-4-10-2 s-1)was obtained from commercial bonded strain gauges. Intermediate rate data ( 10-4 s-1) was obtained from time of flight ultrasonic measurements. Shock rate data was obtained by examining the elastic precursor using shock pins and PDV (photonic Doppler velocimetry). Correction for the adiabatic versus thermal nature of the disparate strain-rate regimes have been made. Additionally, the implications of the uniaxial strain nature of the shock elastic precursor are examined with respect to comparison with uniaxial stress lower rate data.

  13. Coating formation by plasma electrolytic oxidation on ZC71/SiC/12p-T6 magnesium metal matrix composite

    NASA Astrophysics Data System (ADS)

    Arrabal, R.; Matykina, E.; Skeldon, P.; Thompson, G. E.

    2009-02-01

    Plasma electrolytic oxidation (PEO) of a ZC71/SiC/12p-T6 magnesium metal matrix composite (MMC) is investigated in relation to coating growth and corrosion behaviour. PEO treatment was undertaken at 350 mA cm -2 (rms) and 50 Hz with a square waveform in stirred 0.05 M Na 2SiO 3.5H 2O/0.1 M KOH electrolyte. The findings revealed thick, dense oxide coatings, with an average hardness of 3.4 GPa, formed at an average rate of ˜1 μm min -1 for treatment times up to 100 min and ˜0.2 μm min -1 for later times. The coatings are composed mainly of MgO and Mg 2SiO 4, with an increased silicon content in the outer regions, constituting <10% of the coating thickness. SiC particles are incorporated into the coating, with formation of a silicon-rich layer at the particle/coating interface due to exposure to high temperatures during coating formation. The distribution of the particles in the coating indicated growth of new oxide at the metal/coating interface. The corrosion rate of the MMC in 3.5% NaCl is reduced by approximately two orders of magnitude by the PEO treatment.

  14. Renal cell carcinomas with t(6;11)(p21;q12) presenting with tubulocystic renal cell carcinoma-like features.

    PubMed

    Rao, Qiu; Zhang, Xiu-Mei; Tu, Pin; Xia, Qiu-Yuan; Shen, Qin; Zhou, Xiao-Jun; Shi, Qun-Li

    2013-01-01

    In this study, we reported an additional genetically confirmed case of renal cell carcinomas (RCCs) with t(6;11)(p21;q12) showing an unusual histological pattern. Histologically, the tumor was entirely composed of small to intermediate sized tubules and cysts. The tubules and cysts were lined by a single layer of flat, hobnail, cuboidal to columnar epithelial cells. Most cells demonstrated abundant eosinophilic cytoplasm with regular, round or oval nuclei and some inconspicuous nucleoli. All these morphological features are suggestive of tubulocystic carcinoma of the kidney. However, the tumor demonstrated moderately (2+) or strongly (3+) positive staining for TFEB, Cathepsin K, Ksp-cadherin, and vimentin but negative for TFE3, CD10, HMB45, melan A, CKpan, and CK7. Using a recently developed TFEB split FISH assay, the presence of TFEB rearrangement was demonstrated. Our results support the clinical application of a TFEB break-apart FISH assay for diagnosis and confirmation of TFEB RCC and further expand the morphologic spectrum that may be present in these neoplasms, sometimes raising a challenging differential diagnosis with other renal tumors. PMID:23826432

  15. Critical assessment of precracked specimen configuration and experimental test variables for stress corrosion testing of 7075-T6 aluminum alloy plate

    NASA Technical Reports Server (NTRS)

    Domack, M. S.

    1985-01-01

    A research program was conducted to critically assess the effects of precracked specimen configuration, stress intensity solutions, compliance relationships and other experimental test variables for stress corrosion testing of 7075-T6 aluminum alloy plate. Modified compact and double beam wedge-loaded specimens were tested and analyzed to determine the threshold stress intensity factor and stress corrosion crack growth rate. Stress intensity solutions and experimentally determined compliance relationships were developed and compared with other solutions available in the literature. Crack growth data suggests that more effective crack length measurement techniques are necessary to better characterize stress corrosion crack growth. Final load determined by specimen reloading and by compliance did not correlate well, and was considered a major source of interlaboratory variability. Test duration must be determined systematically, accounting for crack length measurement resolution, time for crack arrest, and experimental interferences. This work was conducted as part of a round robin program sponsored by ASTM committees G1.06 and E24.04 to develop a standard test method for stress corrosion testing using precracked specimens.

  16. UKIDSS detections of cool brown dwarfs. Proper motions of 14 known >T5 dwarfs and discovery of three new T5.5-T6 dwarfs

    NASA Astrophysics Data System (ADS)

    Scholz, R.-D.; Bihain, G.; Schnurr, O.; Storm, J.

    2012-05-01

    Aims: We contribute to improving the census of cool brown dwarfs (late-T and Y dwarfs) in the immediate solar neighbourhood. Methods: By combining near-infrared (NIR) data of UKIDSS with mid-infrared WISE and other available NIR (2MASS) and red optical (SDSS z-band) multi-epoch data we detected high proper motion (HPM) objects with colours typical of late spectral types (>T5). We used NIR low-resolution spectroscopy for the classification of new candidates. Results: We determined new proper motions for 14 known T5.5-Y0 dwarfs, many of which are significantly (>2-10 times) more accurate than previous ones. We detected three new candidates, ULAS J0954+0623, ULAS J1152+0359, and ULAS J1204-0150, by their HPMs and colours. Using previously published and new UKIDSS positions of the known nearby T8 dwarf WISE J0254+0223 we improved its trigonometric parallax to 165 ± 20 mas. For the three new objects we obtained NIR spectroscopic follow-up with LBT/LUCIFER classifying them as T5.5 and T6 dwarfs. With their estimated spectroscopic distances of about 25-30 pc, their proper motions of about 430-650 mas/yr lead to tangential velocities of about 50-80 km s-1, typical of the Galactic thin-disk population. Based on observations with the Large Binocular Telescope (LBT)Tables 1-5 are available in electronic form at http://www.aanda.org

  17. Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy.

    PubMed

    Brooks, Emily K; Tobias, Menachem E; Yang, Shuying; Bone, Lawrence B; Ehrensberger, Mark T

    2016-02-01

    This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin ) and outer layer resistance (Rout ) were lower for samples without cells cultured on the surface at 3 days (Rin  = 2.64 e4 Ω/cm(2) , Rout  = 140 Ω/cm(2) ) compared to 21 days (Rin  = 3.60 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin  = 1.88 e5 Ω/cm(2) , Rout  = 1060 Ω/cm(2) ) which was observed to increase over time (21 day, Rin  = 2.99 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. PMID:25715925

  18. Protein engineering by random mutagenesis and structure-guided consensus of Geobacillus stearothermophilus Lipase T6 for enhanced stability in methanol.

    PubMed

    Dror, Adi; Shemesh, Einav; Dayan, Natali; Fishman, Ayelet

    2014-02-01

    The abilities of enzymes to catalyze reactions in nonnatural environments of organic solvents have opened new opportunities for enzyme-based industrial processes. However, the main drawback of such processes is that most enzymes have a limited stability in polar organic solvents. In this study, we employed protein engineering methods to generate a lipase for enhanced stability in methanol, which is important for biodiesel production. Two protein engineering approaches, random mutagenesis (error-prone PCR) and structure-guided consensus, were applied in parallel on an unexplored lipase gene from Geobacillus stearothermophilus T6. A high-throughput colorimetric screening assay was used to evaluate lipase activity after an incubation period in high methanol concentrations. Both protein engineering approaches were successful in producing variants with elevated half-life values in 70% methanol. The best variant of the random mutagenesis library, Q185L, exhibited 23-fold-improved stability, yet its methanolysis activity was decreased by one-half compared to the wild type. The best variant from the consensus library, H86Y/A269T, exhibited 66-fold-improved stability in methanol along with elevated thermostability (+4.3°C) and a 2-fold-higher fatty acid methyl ester yield from soybean oil. Based on in silico modeling, we suggest that the Q185L substitution facilitates a closed lid conformation that limits access for both the methanol and substrate excess into the active site. The enhanced stability of H86Y/A269T was a result of formation of new hydrogen bonds. These improved characteristics make this variant a potential biocatalyst for biodiesel production. PMID:24362426

  19. Protein Engineering by Random Mutagenesis and Structure-Guided Consensus of Geobacillus stearothermophilus Lipase T6 for Enhanced Stability in Methanol

    PubMed Central

    Dror, Adi; Shemesh, Einav; Dayan, Natali

    2014-01-01

    The abilities of enzymes to catalyze reactions in nonnatural environments of organic solvents have opened new opportunities for enzyme-based industrial processes. However, the main drawback of such processes is that most enzymes have a limited stability in polar organic solvents. In this study, we employed protein engineering methods to generate a lipase for enhanced stability in methanol, which is important for biodiesel production. Two protein engineering approaches, random mutagenesis (error-prone PCR) and structure-guided consensus, were applied in parallel on an unexplored lipase gene from Geobacillus stearothermophilus T6. A high-throughput colorimetric screening assay was used to evaluate lipase activity after an incubation period in high methanol concentrations. Both protein engineering approaches were successful in producing variants with elevated half-life values in 70% methanol. The best variant of the random mutagenesis library, Q185L, exhibited 23-fold-improved stability, yet its methanolysis activity was decreased by one-half compared to the wild type. The best variant from the consensus library, H86Y/A269T, exhibited 66-fold-improved stability in methanol along with elevated thermostability (+4.3°C) and a 2-fold-higher fatty acid methyl ester yield from soybean oil. Based on in silico modeling, we suggest that the Q185L substitution facilitates a closed lid conformation that limits access for both the methanol and substrate excess into the active site. The enhanced stability of H86Y/A269T was a result of formation of new hydrogen bonds. These improved characteristics make this variant a potential biocatalyst for biodiesel production. PMID:24362426

  20. BCL2 accelerates inflammation-induced BALB/c plasmacytomas and promotes novel tumors with coexisting T(12;15) and T(6;15) translocations.

    PubMed

    Silva, Santiago; Kovalchuk, Alexander L; Kim, Joong Su; Klein, George; Janz, Siegfried

    2003-12-15

    Previous studies on peritoneal plasmacytomas (PCTs) in BALB/c (C) mice suggested that the enforced expression of the death repressor BCL2 in B cells might facilitate the malignant transformation of aberrant B cells containing Myc-activating T(12;15) translocations, generating an improved model of plasmacytomagenesis. To investigate this hypothesis, we backcrossed a human BCL2 transgene onto strain C and performed a PCT induction study with pristane in the newly generated C.BCL2 congenics. In specific pathogen-free-maintained C.BCL2 mice, PCT incidence (19 of 34, 56%) was 24 times higher than in specific pathogen-free-maintained C mice (1 of 44, 2.3%), and tumor onset (113 days) was half that of conventionally maintained C mice (220 days). BCL2 transgenic PCT harbored T(12;15) translocations (12 of 12 tumors) with an unusual clustering of translocation breakpoints in the near 5' flank of Myc (4 of 5 tumors, 80%). Five tumors contained coexisting T(12;15) and T(6;15) translocations (not observed in >300 karyotyped PCTs from conventionally maintained C mice). BCL2 transgenic C57BL/6 mice exclusively developed B lymphomas (11 of 20, 55%) that also contained T(12;15) translocations (11 of 11 cases) with breakpoints in the near 5' flank of Myc (five of five tumors). We conclude that BCL2 accelerates PCT with novel Myc-activating translocations independently of environmental antigen stimulation. Accelerated plasmacytomagenesis in strain C.BCL2 may be useful for designing and testing BCL2 inhibition strategies in human plasma cell tumors overexpressing BCL2, such as Waldenström's macroglobulinemia and multiple myeloma. PMID:14695177

  1. Study on the 8He ground state via 8He(p, d)7He and 8He(p, t)6He reaction at 82.3 MeV/nucleon

    NASA Astrophysics Data System (ADS)

    Lou, J. L.; Ye, Y. L.; Pang, D. Y.; Cao, Z. X.; Jiang, D. X.

    2013-03-01

    The differential cross sections for reactions 8He(p, d)7Heg.s and 8He(p, t)6He2+ were measured by the coincidence of d + 6 He and t + 4He in a wide angular range from 15 to 130 degree in the center-of-mass system. The cross sections of the 8He(p, t)6Heg.s reaction were extremely lower than that of 8He(p, t)6He2+ reaction, and was not obtained from the present data. The experimental results were compared to the preliminary theoretical calculations in the frame of adiabatic distorted-wave approximation with the code Fresco. The results show that the configuration of (1p3/2)2(1p1/2)2 may have some probability in the ground state wave function of 8He. The cluster structure of 8He = 5H + 3H could not be neglected.

  2. Cloning, purification and preliminary crystallographic analysis of Ara127N, a GH127 β-l-arabinofuranosidase from Geobacillus stearothermophilus T6

    PubMed Central

    Lansky, Shifra; Salama, Rachel; Dann, Roie; Shner, Izhak; Manjasetty, Babu A.; Belrhali, Hassan; Shoham, Yuval; Shoham, Gil

    2014-01-01

    The l-arabinan utilization system of Geobacillus stearothermophilus T6 is composed of five transcriptional units that are clustered within a 38 kb DNA segment. One of the transcriptional units contains 11 genes, the last gene of which (araN) encodes a protein, Ara127N, that belongs to the newly established GH127 family. Ara127N shares 44% sequence identity with the recently characterized HypBA1 protein from Bifidobacterium longum and thus is likely to function similarly as a β-l-arabinofuranosidase. β-l-Arabinofuranosidases are enzymes that hydrolyze β-l-arabinofuranoside linkages, the less common form of such linkages, a unique enzymatic activity that has been identified only recently. The interest in the structure and mode of action of Ara127N therefore stems from its special catalytic activity as well as its membership of the new GH127 family, the structure and mechanism of which are only starting to be resolved. Ara127N has recently been cloned, overexpressed, purified and crystallized. Two suitable crystal forms have been obtained: one (CTP form) belongs to the monoclinic space group P21, with unit-cell parameters a = 104.0, b = 131.2, c = 107.6 Å, β = 112.0°, and the other (RB form) belongs to the orthorhombic space group P212121, with unit-cell parameters a = 65.5, b = 118.1, c = 175.0 Å. A complete X-ray diffraction data set has been collected to 2.3 Å resolution from flash-cooled crystals of the wild-type enzyme (RB form) at −173°C using synchrotron radiation. A selenomethionine derivative of Ara127N has also been prepared and crystallized for multi-wavelength anomalous diffraction (MAD) experiments. Crystals of selenomethionine Ara127N appeared to be isomorphous to those of the wild type (CTP form) and enabled the measurement of a three-wavelength MAD diffraction data set at the selenium absorption edge. These data are currently being used for detailed three-dimensional structure determination of the Ara127N protein. PMID:25084377

  3. Cloning, purification and preliminary crystallographic analysis of Ara127N, a GH127 β-L-arabinofuranosidase from Geobacillus stearothermophilus T6.

    PubMed

    Lansky, Shifra; Salama, Rachel; Dann, Roie; Shner, Izhak; Manjasetty, Babu A; Belrhali, Hassan; Shoham, Yuval; Shoham, Gil

    2014-08-01

    The L-arabinan utilization system of Geobacillus stearothermophilus T6 is composed of five transcriptional units that are clustered within a 38 kb DNA segment. One of the transcriptional units contains 11 genes, the last gene of which (araN) encodes a protein, Ara127N, that belongs to the newly established GH127 family. Ara127N shares 44% sequence identity with the recently characterized HypBA1 protein from Bifidobacterium longum and thus is likely to function similarly as a β-L-arabinofuranosidase. β-L-Arabinofuranosidases are enzymes that hydrolyze β-L-arabinofuranoside linkages, the less common form of such linkages, a unique enzymatic activity that has been identified only recently. The interest in the structure and mode of action of Ara127N therefore stems from its special catalytic activity as well as its membership of the new GH127 family, the structure and mechanism of which are only starting to be resolved. Ara127N has recently been cloned, overexpressed, purified and crystallized. Two suitable crystal forms have been obtained: one (CTP form) belongs to the monoclinic space group P21, with unit-cell parameters a = 104.0, b = 131.2, c = 107.6 Å, β = 112.0°, and the other (RB form) belongs to the orthorhombic space group P212121, with unit-cell parameters a = 65.5, b = 118.1, c = 175.0 Å. A complete X-ray diffraction data set has been collected to 2.3 Å resolution from flash-cooled crystals of the wild-type enzyme (RB form) at -173°C using synchrotron radiation. A selenomethionine derivative of Ara127N has also been prepared and crystallized for multi-wavelength anomalous diffraction (MAD) experiments. Crystals of selenomethionine Ara127N appeared to be isomorphous to those of the wild type (CTP form) and enabled the measurement of a three-wavelength MAD diffraction data set at the selenium absorption edge. These data are currently being used for detailed three-dimensional structure determination of the Ara127N protein. PMID:25084377

  4. Francisella tularensis IglG Belongs to a Novel Family of PAAR-Like T6SS Proteins and Harbors a Unique N-terminal Extension Required for Virulence.

    PubMed

    Rigard, Mélanie; Bröms, Jeanette E; Mosnier, Amandine; Hologne, Maggy; Martin, Amandine; Lindgren, Lena; Punginelli, Claire; Lays, Claire; Walker, Olivier; Charbit, Alain; Telouk, Philippe; Conlan, Wayne; Terradot, Laurent; Sjöstedt, Anders; Henry, Thomas

    2016-09-01

    The virulence of Francisella tularensis, the etiological agent of tularemia, relies on an atypical type VI secretion system (T6SS) encoded by a genomic island termed the Francisella Pathogenicity Island (FPI). While the importance of the FPI in F. tularensis virulence is clearly established, the precise role of most of the FPI-encoded proteins remains to be deciphered. In this study, using highly virulent F. tularensis strains and the closely related species F. novicida, IglG was characterized as a protein featuring a unique α-helical N-terminal extension and a domain of unknown function (DUF4280), present in more than 250 bacterial species. Three dimensional modeling of IglG and of the DUF4280 consensus protein sequence indicates that these proteins adopt a PAAR-like fold, suggesting they could cap the T6SS in a similar way as the recently described PAAR proteins. The newly identified PAAR-like motif is characterized by four conserved cysteine residues, also present in IglG, which may bind a metal atom. We demonstrate that IglG binds metal ions and that each individual cysteine is required for T6SS-dependent secretion of IglG and of the Hcp homologue, IglC and for the F. novicida intracellular life cycle. In contrast, the Francisella-specific N-terminal α-helical extension is not required for IglG secretion, but is critical for F. novicida virulence and for the interaction of IglG with another FPI-encoded protein, IglF. Altogether, our data suggest that IglG is a PAAR-like protein acting as a bi-modal protein that may connect the tip of the Francisella T6SS with a putative T6SS effector, IglF. PMID:27602570

  5. An Experimental Investigation of the Effects of Vacuum Environment on the Fatigue Life, Fatigue-Crack-Growth Behavior, and Fracture Toughness of 7075-T6 Aluminum Alloy. Ph.D. Thesis - North Carolina State Univ.

    NASA Technical Reports Server (NTRS)

    Hudson, C. M.

    1972-01-01

    Axial load fatigue life, fatigue-crack propagation, and fracture toughness tests were conducted on 0.090-inch thick specimens made of 7075-T6 aluminum alloy. The fatigue life and fatigue-crack propagation experiments were conducted at a stress ratio of 0.02. Maximum stresses ranged from 33 to 60 ksi in the fatigue life experiments, and from 10 to 40 ksi in the fatigue-crack propagation experiments, and fatigue life experiments were conducted at gas pressures of 760, 0.5, 0.05, and 0.00000005 torr. Fatigue-crack-growth and fracture toughness experiments were conducted at gas pressures of 760 and 5 x 10 to the minus 8th power torr. Residual stress measurements were made on selected fatigue life specimens to determine the effect of such stresses on fatigue life. Analysis of the results from the fatigue life experiments indicated that fatigue life progressively increased as the gas pressure decreased. Analysis of the results from the fatigue-crack-growth experiments indicates that at low values of stress-intensity range, the fatigue crack growth rates were approximately twice as high in air as in vacuum. Fracture toughness data showed there was essentially no difference in the fracture toughness of 7075-T6 in vacuum and in air.

  6. Isolation of cosmids corresponding to the chromosome breakpoints of a de novo autosomal translocation, t(6;19)(p21;q13.1), in a patient with multicystic renal dysplasia.

    PubMed

    Groenen, P M; Garcia, E; Thoelen, R; Aly, M; Schoenmakers, E F; Devriendt, K; Fryns, J P; Van de Ven, W J

    1996-01-01

    Hydronephrosis caused by pelvi-ureteric junction obstruction (PUJO) is a frequent urological malformation assumed to result from a deficient development of the ureteric bud. The exact etiology of pelvi-ureteric junction stenosis is unknown, but there is convincing evidence for a genetic cause, with linkage analysis predicting a hereditary hydronephrosis locus on chromosome 6p. We encountered a patient with a de novo autosomal t(6;19)(p21;q13.1) and attendant bilateral multicystic renal dysplasia (MRD), bilateral PUJO resulting in massive hydronephrosis, and an associated von Mayer-Rokitansky-Kuster disorder. On the basis of the presumption that in this patient the putative hydronephrosis gene might be disrupted by the translocation, we sought to isolate DNA from the breakpoint regions as the initial step in a strategy to identify genes affected by the t(6; 19). Using sequential rounds of fluorescence in situ hybridization (FISH) with cosmids selected from a detailed integrated map of the long arm of chromosome 19, we have identified a cosmid clone that spans the breakpoint. The position of the breakpoint was further localized by Southern blot analysis. Using a vectorette PCR approach, rearranged DNA fragments were isolated and, by comparative nucleotide sequence analysis, these were shown to contain ectopic sequences. A cosmid clone containing these ectopic sequences was isolated and shown by CASH (chromosome assignment using somatic cell hybrids) and FISH (fluorescence in situ hybridization) analysis to map to the short arm of chromosome 6 and to span the breakpoint found in the MRD patient. The isolated cosmid clones are useful reagents for analysis of other MRD patients and for the search for genes at or flanking the breakpoints. PMID:9067426

  7. A Comparative Analysis of the Impact of Tool Design to Fatigue Behavior of Single-Sided and Double-Sided Welded Butt Joints of EN AW 6082-T6 Alloy

    NASA Astrophysics Data System (ADS)

    Krasnowski, K.; Dymek, S.

    2013-12-01

    In this paper, the results of fatigue behavior on friction stir welded joints of aluminum alloy EN AW 6082-T6 are reported. In particular, the study presents the influence of the geometry of a welding tool on fatigue strengths and tensile strengths. The test joints were prepared as single side welded and double side welded by FSW. The welding was performed at various linear welding speeds (224, 560, and 900 mm/min) and one rotational speed of 710 rev./min using three different tool shapes. The results of macro examination and tensile test led to the selection of a single set of tool movement parameters at which the test joints for fatigue test were made. Samples were tested in two states of surface condition, i.e., "as-welded" and with mechanically removed marks left by rotating and moving tool during FSW process. Studies have shown that fatigue behavior of FSW joints depends on the tool shape used in the welding process as well as the surface condition of welded joints and manner of joint production.

  8. Identification of ZCCHC8 as fusion partner of ROS1 in a case of congenital glioblastoma multiforme with a t(6;12)(q21;q24.3).

    PubMed

    Coccé, Mariela C; Mardin, Balca R; Bens, Susanne; Stütz, Adrian M; Lubieniecki, Fabiana; Vater, Inga; Korbel, Jan O; Siebert, Reiner; Alonso, Cristina N; Gallego, Marta S

    2016-09-01

    Congenital gliobastoma multiforme (GBM) is rare and little is known about the molecular defects underlying the initiation and progression of this tumor type. We present a case of congenital GBM analyzed by conventional cytogenetics, fluorescence in situ hybridization, array comparative genomic hybridization and next generation sequencing. On cytogenetic analysis we detected a reciprocal translocation t(6;12)(q21;q24.3). By sequencing, the translocation was shown to form a fusion between the 5' region of ZCCHC8 and the 3' region of ROS1. RT-PCR analyses confirmed the existence of an in-frame fusion transcript with ZCCHC8 exons 1-3 joined to ROS1 exons 36-43. In addition to the ZCCHC8-ROS1 fusion, we detected a deletion in the short arm of chromosome 9, including homozygous loss of the CDKN2A/2B locus in 9p21.3 and heterozygous deletion of the HAUS6 gene in 9p22.1. The latter encodes a protein involved in faithful chromosome segregation by regulating microtubule nucleation and its deletion might be associated with the marked subclonal changes of ploidy observed in the tumor. This report adds the ZCCHC8-ROS1 fusion as oncogenic driver in GBM and supports the role of ROS1 activation in the pathogenesis of a subset of GBM. © 2016 Wiley Periodicals, Inc. PMID:27121553

  9. A 10-year wildlife survey of 15 species of Canadian carnivores identifies new hosts or geographic locations for Trichinella genotypes T2, T4, T5, and T6.

    PubMed

    Gajadhar, Alvin A; Forbes, Lorry B

    2010-02-26

    A survey of wild carnivores in Canada was conducted over a 10-year period to determine the prevalence and genotypes of Trichinella. Muscle samples collected from 1409 animals representing 15 hosts species were enzymatically digested to recover Trichinella larvae. Larvae were recovered from a total of 287 (20.4%) animals and PCR identified four genotypes of Trichinella. Trichinella nativa was found in 5 host species and was the most commonly found genotype. Trichinella T6 was present in 7 species of carnivores, and coyote and badger are new host records for this genotype. The recovery of T. pseudospiralis and T. murrelli from cougars is the first documentation of these species in Canada and in cougars. The cougar was also the only host species in which all four genotypes of Trichinella were identified. Black bears and walruses had the highest tissue levels of larvae in this study and are also the species most frequently associated with human trichinellosis in Canada. This work identifies additional host species and expanded geographic ranges for 4 genotypes of Trichinella in North America. Failure to demonstrate T. spiralis in wildlife and continued negative results from ongoing surveillance activities in swine provide additional evidence that T. spiralis is not present in Canada. PMID:19926223

  10. Genomic and metabolic comparison with Dickeya dadantii 3937 reveals the emerging Dickeya solani potato pathogen to display distinctive metabolic activities and T5SS/T6SS-related toxin repertoire

    PubMed Central

    2014-01-01

    Background The pectinolytic enterobacteria of the Pectobacterium and Dickeya genera are causative agents of maceration-associated diseases affecting a wide variety of crops and ornamentals. For the past decade, the emergence of a novel species D. solani was observed in potato fields in Europe and the Mediterranean basin. The purpose of this study is to search by comparative genomics the genetic traits that could be distinctive to other Dickeya species and be involved in D. solani adaptation to the potato plant host. Results D. solani 3337 exhibits a 4.9 Mb circular genome that is characterized by a low content in mobile elements with the identification of only two full length insertion sequences. A genomic comparison with the deeply-annotated model D. dadantii 3937 strain was performed. While a large majority of Dickeya virulence genes are shared by both strains, a few hundreds genes of D. solani 3337, mostly regrouped in 25 genomic regions, are distinctive to D. dadantii 3937. These genomic regions are present in the other available draft genomes of D. solani strains and interestingly some of them were not found in the sequenced genomes of the other Dickeya species. These genomic regions regroup metabolic genes and are often accompanied by genes involved in transport systems. A metabolic analysis correlated some metabolic genes with distinctive functional traits of both D. solani 3337 and D. dadantii 3937. Three identified D. solani genomic regions also regroup NRPS/PKS encoding genes. In addition, D. solani encodes a distinctive arsenal of T5SS and T6SS-related toxin-antitoxin systems. These genes may contribute to bacteria-bacteria interactions and to the fitness of D. solani to the plant environment. Conclusions This study highlights the genomic specific traits of the emerging pathogen D. solani and will provide the basis for studying those that are involved in the successful adaptation of this emerging pathogen to the potato plant host. PMID:24735398

  11. Unfractionated spleen cells but not natural killer (NK) cells from RFM donors prevent the progression of host-versus-graft disease in murine RFM/(T6 x RFM)F1 chimeras.

    PubMed Central

    Hard, R C; Patel, M R; Keller, L M; Linna, T J

    1988-01-01

    Host-versus-graft (HVG) syndrome is the fatal allogenic disease which develops in susceptible strains of inbred mice following their perinatal inoculation with related F1 hybrid spleen cells. Deaths are caused by pathogenic immune complexes. It is thought that the antibody components of these complexes are produced by F1 donor B cells stimulated by the allogenic HVG reaction. To complement previous work that showed that lethal disease could be prevented if the HVG response was suppressed, the present studies tested whether or not it could also be prevented by augmenting HVG reactivity with the adoptive transfer of spleen cells syngenic with the host. The data show that unfractionated RFM spleen cells given on Days 13-14 prevented lethal disease in 86% of RFM/(T6 x RFM)F1 chimeras. Successful therapy was associated with the suppression of formation of nephropathic-immune complexes, and with the rejection of F1 donor cells or their gradual replacement by host cells. RFM spleen cells enriched for NK activity by a new improved method not only failed to prevent HVG disease but appeared to exacerbate it. This was also true of spleen cells that had been activated in vitro for 3 days with IL-2, a procedure that greatly enhanced their cytolytic activity against YAC-1 targets. It is suggested that therapy with NK cells failed, even after IL-2 activation, because they had no effect on proliferating and antibody-forming F1 donor cells that had engrafted in large numbers in the lymph nodes of the RFM hosts. PMID:3258280

  12. A t(6;12)(q23;p13) results in the fusion of ETV6 to a novel gene, STL, in a B-cell ALL cell line.

    PubMed

    Suto, Y; Sato, Y; Smith, S D; Rowley, J D; Bohlander, S K

    1997-04-01

    ETV6 (TEL) is rearranged in various types of hematologic malignancies. The B-cell precursor acute lymphoblastic leukemia (ALL) cell line SUP-B2 has a t(6;12)(q23;p13) involving ETV6 at 12p13 and a submicroscopic deletion of the other ETV6 allele. The reciprocal translocation results in the fusion of ETV6 to a previously unknown gene at 6q23, which we named STL (six-twelve leukemia gene). Both reciprocal fusion transcripts can be detected: On the der(6) chromosome, the ETV6/STL mRNA shows an apparently out of frame fusion of ETV6 at nucleotide 187 to STL, which would result in the addition of 14 amino acids to the first 54 amino acids of ETV6. On the der(12) chromosome three different variants of the STL/ETV6 fusion mRNA could be detected; variable size segments were inserted at the breakpoint between STL and ETV6 exon 3. One of these variants could give rise to a protein in which the first 54 amino acids of ETV6 are replaced by 12 amino acids from one of the STL short open reading frames. Sequence analysis of a 1.4 kb STL cDNA clone from a skeletal muscle library revealed no long open reading frames. This cell line will be very useful in studying the different mechanisms by which alterations of ETV6 contribute to leukemogenesis and in testing the hypothesis that ETV6 might act as a tumor suppressor gene. PMID:9087565

  13. Phylogenomics characterization of a highly virulent Edwardsiella strain ET080813(T) encoding two distinct T3SS and three T6SS gene clusters: Propose a novel species as Edwardsiella anguillarum sp. nov.

    PubMed

    Shao, Shuai; Lai, Qiliang; Liu, Qin; Wu, Haizhen; Xiao, Jingfan; Shao, Zongze; Wang, Qiyao; Zhang, Yuanxing

    2015-02-01

    As important zoonotic organisms causing infections in humans, Edwardsiella bacteria are also notorious leading fish pathogens haunting worldwide aquaculture industries. However, the taxa are now widely recognized to be misclassified, which hurdled the understanding of the epidemiology and development of effective diagnostics and vaccines. Currently the genus Edwardsiella consists of three species Edwardsiella tarda, E. ictaluri, and E. hoshinae. Previous phylogenomic analysis revealed that E. tarda strains display two major highly divergent genomic types (genotypes), EdwGI and EdwGII, and the former represents a genotype of fish-pathogenic isolates and being recently proposed as a novel species E. piscicida, sp. nov. Here multiple phylogenetic analyses and the genome-level comparisons of EdwGI strains disclose that the phylogroup strains from diseased eel formed an obviously distinct cluster that could be equated with a new species status. The phylogenetic evidence for the new species assignment was also supported by corresponding DNA-DNA hybridization estimation values and by phenotypic characteristics. Interestingly, further comparative genomics reveals that these strains have acquired the locus of enterocyte effacement (LEE) genes and as a result these bacteria contain at least 2 sets of distinct T3SS and 3 sets of T6SS gene clusters, respectively. It is therefore proposed that the phylogroup strains from diseased eel should be classified as Edwardisella anguillarum sp. nov., and the type strain is ET080813(T) (=DSM27202(T)=CCUG 64215(T)=CCTCC AB2013118(T)=MCCC 1K00238(T)). These findings will contribute to development of species-specific control measures against Edwardsiella bacterium in aquatic animals, while also shedding light on the pathogenesis evolution in Edwardsiella bacterium. PMID:25466920

  14. Fatigue Strengths of Aircraft Materials: Axial-Load Fatigue Tests on Edge-Notched Sheet Specimens of 2024-T3 and 7075-T6 Aluminum Alloys and of SAE 4130 Steel with Notch Radii of 0.004 and 0.070 inch

    NASA Technical Reports Server (NTRS)

    Grover, H. J.; Hyler, W. S.; Jackson, L. R.

    1959-01-01

    The present report gives results of axial-load fatigue tests on notched specimens of three sheet materials: 2024-T3 and 7075-T6 aluminum alloys and normalized SAE 4130 steel. Two edge-notched specimens were designed and tested, each having a theoretical stress-concentration factor K(sub t) = 4.0. The radii of the notches were 0.004 and 0.070 inch. Tests of these specimens were run at two levels of nominal mean stress: 0 and 20,000 psi. Results of these studies extended information previously reported on tests of specimens with varying notch severity. They afford data on the variation of fatigue-strength reduction with notch radius and on the potential usefulness of Neuber's technical stress-concentration factor K(sub n).

  15. Effects of Applied Load on 6061-T6 Aluminum Joined Employing a Novel Friction Bonding Process

    SciTech Connect

    Douglas E. Burkes; Neil P. Hallinan; Karen L. Shropshire; Peter B. Wells

    2008-12-01

    Friction bonding is under consideration for use in mass production of plate-type nuclear fuels for research reactors. This article discusses the effects of applied load (the most important process parameter for fabrication of these fuels) on temperature distribution, microstructure, and mechanical properties. Friction bonding experiments showed that tool geometry caused temperature gradients across the tool surface. Temperatures at the joint interface suggested the advancing side of the tool produced a majority of the frictional heat, while the retreating side of the tool mainly forged the plasticized material while bonding increased with applied load. The microstructure across the tool surface was also altered and, as a function of applied load, affected the mechanical properties. The 6061 aluminum alloy had mechanical properties close to a T4 temper after processing. Results documented in this article will aid in continual enhancement of friction bonding for nuclear fuel plate fabrication, and will hopefully contribute to continued advancement of friction stir welding (FSW) state of the art.

  16. Recreation Expenditures by U. S. Consumers, 1929-l979. Publication T-6-135.

    ERIC Educational Resources Information Center

    Kitchen, James W.; And Others

    This study explored trends in how Americans spent disposable personal income (DPI) on recreational activities from 1929 to 1979. Statistics were compiled from the Economic Report of the President and the United States Department of Commerce. Twelve classifications of recreation expenditures are presented: (1) books and maps; (2) magazines,…

  17. Low cost corrosion damage mitigation and improved fatigue performance of low plasticity burnished 7075-T6

    NASA Astrophysics Data System (ADS)

    Prevéy, Paul S.; Cammett, John

    2001-10-01

    Low plasticity burnishing (LPB) has been investigated as a surface enhancement process and corrosion mitigation method for aging aircraft structural applications. Compressive residual stresses reaching the alloy yield strength and extending to a depth of 1.25 mm (0.050 in.) deeper than typical corrosion damage is achievable. Excellent surface finish can be achieved with no detectable metallurgical damage to surface and subsurface material. Salt fog exposures of 100 and 500 h reduced the fatigue strength at 2×106 cycles by 50%. The LPB of the corroded surface, without removal of the corrosion product or pitted material, restored the 2×106 fatigue strength to greater than that of the original machined surface. The fatigue strength of the corroded material in the finite life regime (104 to 106 cycles) after LPB was 140 MPa (20 ksi) higher than the original uncorroded alloy and increased the life by an order of magnitude. Ease of adaptation to computer numerical control (CNC) machine tools allows LPB processing at costs and speeds comparable to machining operations. Low plasticity burnishing offers a promising new technology for mitigation of corrosion damage and improved fatigue life of aircraft structural components with significant cost and time savings over current practices.

  18. Homogeneity of Mechanical Properties of Underwater Friction Stir Welded 2219-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Liu, H. J.; Zhang, H. J.; Yu, L.

    2011-11-01

    Underwater friction stir welding (FSW) has been demonstrated to be available for the improvement in tensile strength of normal FSW joints. In order to illuminate the intrinsic reason for strength improvement through underwater FSW, a 2219 aluminum alloy was underwater friction stir welded and the homogeneity of mechanical properties of the joint was investigated by dividing the joint into three layers. The results indicate that the tensile strength of the three layers of the joint is all improved by underwater FSW, furthermore, the middle and lower layers have larger extent of strength improvement than the upper layer, leading to an increase in the homogeneity of mechanical properties of the joint. The minimum hardness value of each layer, especially the middle and lower layers, is improved under the integral water cooling effect, which is the intrinsic reason for the strength improvement of underwater joint.

  19. Detailed summary of the working group on environmental control (T6)

    SciTech Connect

    Wilhelm Bialowons; Chris Laughton; Andrei Seryi

    2002-11-21

    For the next generation of large accelerators, the civil engineering of accelerator tunnels and associated underground enclosures will be a major component of the technical challenge of building such machines. Because of the large scale involved, the engineering will be required to be as cost-effective as possible, and issues such as ground motion and artificial sources of vibration in the environment will need to be carefully considered. installation and alignment of the machine components will be tasks of unprecedented scope, and will require unprecedented precision. Examine in detail the most important and most difficult aspects of these challenges, both from the point of view of performance and cost-effectiveness. In particular, identify what the site requirements are for the different machines under discussion (JLC, NLC, TESLA, VLHC, Muon source), and describe how tunneling methods are affected by them. Identify, for the different types of accelerators, the different length scales that are involved in defining the alignment tolerances, and what are the tolerances over that length scale. Specify the R and D efforts needed to define the scope of the most critical challenges, and prioritize the efforts, in terms of the potential to provide maximal performance and/or cost-effectiveness. Establish a technology-limited time line, and the resource requirements, for the most important of these efforts.

  20. 7075-T6 and 2024-T351 Aluminum Alloy Fatigue Crack Growth Rate Data

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Wright, Christopher W.; Johnston, William M., Jr.

    2005-01-01

    Experimental test procedures for the development of fatigue crack growth rate data has been standardized by the American Society for Testing and Materials. Over the past 30 years several gradual changes have been made to the standard without rigorous assessment of the affect these changes have on the precision or variability of the data generated. Therefore, the ASTM committee on fatigue crack growth has initiated an international round robin test program to assess the precision and variability of test results generated using the standard E647-00. Crack growth rate data presented in this report, in support of the ASTM roundrobin, shows excellent precision and repeatability.

  1. Multiscale Study of Interfacial Intermetallic Compounds in a Dissimilar Al 6082-T6/Cu Friction-Stir Weld

    NASA Astrophysics Data System (ADS)

    Avettand-Fenoël, M. N.; Taillard, R.; Ji, G.; Goran, D.

    2012-12-01

    The objective of this work was to characterize the Al x Cu y intermetallic compounds (IMCs) formed at the abutting interface during solid-state friction-stir welding (FSW) of 6082 aluminum alloy and pure copper. As IMCs are potential sources of flaws in case of mechanical loading of welds, their study is essential at various scale lengths. In the present case, they have been identified by neutron diffraction, electron backscattered diffraction, and transmission electron microscopy. Neutron diffraction analyses have shown that a shift of the tool from the interface, in particular towards the Cu part, generates an increase of the IMCs' volume fraction. In accordance with an exacerbation of its kinetics of formation by FSW, a 4- μm-thick layer has precipitated at the interface despite the shortness of the thermal cycle. This layer is composed of two sublayers with the Al4Cu9 and Al2Cu stoichiometry, respectively. Convergent beam electron diffraction analyses have, however, disclosed that the crystallography of the current Al2Cu compound does not comply with the usual tetragonal symmetry of this phase. The Al2Cu phase formation results from both the local chemical composition and thermodynamics, whereas the development of Al4Cu9 is rather due to both the local chemical composition and the shortness of the local FSW thermal cycle.

  2. Prediction of low-cycle fatigue-life by acoustic emission—2: 7075-T6 aluminum alloy

    SciTech Connect

    Baram, J.; Rosen, M.

    1981-01-01

    Low-cycle fatigue tests were conducted by tension-compression until rupture, on a 2024-T3 aluminum alloy sheet. Initial crack sizes and orientations in the fatigue specimens were found to be randomly distributed. Acoustic emission was continuously monitored during the tests. Every few hundred cycles, the acoustic signal having the highest peak-amplitude, was recorded as an extremal event for the elapsed period. This high peak-amplitude is related to a fast crack propagation rate through a phenomenological relationship. The extremal peakamplitudes are shown by an ordered statistics treatment, to be extremally distributed. The statistical treatment enables the prediction of the number of cycles left until failure. Predictions performed a-posteriori based on results gained early in each fatigue test are in good agreement with actual fatigue lives. The amplitude distribution analysis of the acoustic signals emitted during cyclic stress appears to be a promising nondestructive method of predicting fatigue life.

  3. The effects of maintaining temperature in annealing heat treatment for an FSWed 6061-T6 Al alloy.

    PubMed

    Lee, Seung-Jun; Han, Min-Su; Kim, Seong-Jong

    2013-08-01

    The technological development of all kinds of lightweight transportation devices including vehicles, aircraft, ships, etc. has progressed markedly with the demand for energy saving and environmental protection. Aluminum alloy is in the spotlight as it is a suitable environmentally friendly material. However, deformation is a major problem during the welding process because aluminum alloy has a large thermal expansion coefficient. In addition, it is known that its corrosion resistance is excellent; nevertheless, in practice, considerable corrosion is generated and this is a major problem. To solve this problem, the friction stir welding (FSW) technology is applied extensively at various industrial fields as a new welding technique. This method involves a process in which materials are joined by frictional heat and physical force. Therefore, we evaluated improvements in mechanical properties and corrosion resistance through annealing heat treatment after FSW. The electrochemical experiment did not show a significant difference. However, the microstructure observation showed defectless, fine crystal particles, indicating excellent properties at 200-225°C. PMID:23920178

  4. Discernible but limited introgression has occurred where Trichinella nativa and the T6 genotype occur in sympatry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genetic diversity within and among parasite populations provides clues to their evolutionary history. Here, we sought to determine whether mitochondrial and microsatellite variation could be used to evaluate the extent of differentiation, gene flow and historical reproductive isolation among the...

  5. External And Internal Work Of A T-6 Paraplegic Propelling A Wheelchair And Arm Cranking A Cycle Ergometer: Case Study

    NASA Astrophysics Data System (ADS)

    Novak, Charles W.

    1982-02-01

    In this, the International Year of the Disabled, attention is directed among other areas toward rehabilitation and sports participation of wheelchair users. As an application of movement analysis in medicine and rehabilitation and as an application of sports research using biomechanics, this investigation was performed to compare the results of two methods of gathering data on the stress of wheelchair propelling at equivalent work loads and to account for differences in physiological responses with a mechanical analysis of wheelchair propelling. Physiological data collected were heart rate, systolic blood pressure, and rate-pressure product. A biomechanical cinematography analysis was used to determine external work in wheelchair propelling and to determine the extent to which modifications in segment actionsoccurred during increasing magnitude of work. A cycle ergometer was adjusted to replicate external work loads performed during wheelchair propelling. A t-test of equivalent external work loads indicated that heart rate was not different between the two exercise modes at the .05 level of significance. The t-test did indicate a significant difference in systolic blood pressure and rate-pressure product at the .05 level of significance. The biomechanical analysis of wheelchair propelling established that an increase in external work was accomplished by a decrease in the range of motion and an increase in the speed of movement. During cycle ergometry the range and speed of movement remained the same while resistance was increased. Results of the study established that while heart rate for equivalent external work loads was the same for wheelchair propelling and arm cranking cycle ergometry, systolic blood pressure and rate-pressure product were not the same. The suggestion was that some means of propelling a wheelchair other than that which is con-sidered "standard" might be considered which produces less stressful responses in wheelchair users.

  6. A damage tolerance comparison of 7075-T6 aluminum alloy and IM7/977-2 carbon/epoxy

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Lance, David G.; Hodge, Andrew J.

    1991-01-01

    A comparison of low velocity impact damage between one of the strongest aluminum alloys, to a new, damage tolerant resin system as a matrix for high strength carbon fibers was examined in this study. The aluminum and composite materials were used as face sheets on a 0.13 g/cu cm aluminum honeycomb. Four levels of impact energy were used; 2.6 J, 5.3 J, 7.8 J and 9.9 J. The beams were compared for static strength and fatique life by use of the four-point bend flexure test. It was found that in the undamaged state the specific strength of the composite face sheets was about twice that of the aluminum face sheets. A sharp drop in strength was observed for the composite specimens impacted at the lowest (2.6J) energy level, but the overall specific strength was still higher than for the aluminum specimens. At all impact energy levels tested, the static specific strength of the composite face sheets were significantly higher than the aluminum face sheets. The fatigue life of the most severely damaged composite specimen was about 17 times greater than the undamaged aluminum specimens when cycled at 1 Hz between 20 percent and 85 percent of ultimate breaking load.

  7. U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR LABORATORY ASSISTANT TRAINING PLAN--GENERAL (UA-T-6.0)

    EPA Science Inventory

    The purpose of this SOP is to describe the training sequence of incoming student laboratory assistants. The procedure is designed to provide them with an overview of the project in terms of project goals, structure, and laboratory needs. This overview familiarizes the student l...

  8. Experimental Investigation of Effects of Random Loading on the Fatigue Life of Notched Cantilever-Beam Specimens of 7075-T6 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Fralich, Robert W.

    1959-01-01

    Results of random-loading fatigue tests on 125 notched cantilever-beam specimens and constant-amplitude fatigue tests on 46 similar specimens are presented in terms of the root-mean-square value of peak stresses. The results from the two sets of tests are compared on the basis of time to failure, where the results from the constant-amplitude tests are expressed in terms of an equivalent time to failure based on the natural period of vibration. Compared on this basis, failure at the lower stress levels occurred in a shorter time for the random loading than for the constant-amplitude loading, whereas at the higher stress levels failure occurred in the reverse order. A theoretical result for random loading is also presented and compared with the experimental results. The theoretical result shows good agreement with experiment for low values of stress but underestimates the time to failure at the higher stresses.

  9. Design of a 0. 6-m bore wind-and-react 12-T, 6-kA, Nb sub 3 Sn magnet

    SciTech Connect

    della Corte, A.; Di Pietro, E.; Pasotti, G.; Sacchetti, N.; Spadoni, M. )

    1991-03-01

    This paper presents the design concepts of a Nb{sub 3}Sn wind-and-react (W/R) magnet, wound with a cable-in-conduit (CIC) conductor. The magnet is designed to operate at approximately 6 kA, generating a maximum field of 12 T over a 0.6-m bore. The design of the forced-flow-cooled cable-in-conduit conductor, the winding principles, the heat exchanger effect in the magnet, and the stress analysis on the coil and conductor are reported and discussed.

  10. 22q11.2 Deletion Syndrome due to a Translocation t(6;22) in a Patient Conceived via in vitro Fertilization

    PubMed Central

    Gollo Dantas, Anelisa; Bortolai, Adriana; Moysés-Oliveira, Mariana; Takeno Herrero, Sylvia; Azoubel Antunes, Adriana; Tavares Costa-Carvalho, Beatriz; Ayres Meloni, Vera; Melaragno, Maria Isabel

    2016-01-01

    We report on a patient conceived via in vitro fertilization (IVF) with a 22q11.2 deletion due to an unusual unbalanced translocation involving chromosomes 6 and 22 in a karyotype with 45 chromosomes. Cytogenomic studies showed that the patient has a 3.3-Mb deletion of chromosome 22q and a 0.4-Mb deletion of chromosome 6p, which resulted in haploinsufficiency of the genes responsible for the 22q11.2 deletion syndrome and also of the IRF4 gene, a member of the interferon regulatory factor family of transcription factors, which is expressed in the immune system cells. The rearrangement could be due to the manipulation of the embryo or as a sporadic event unrelated to IVF. Translocation involving chromosome 22 in a karyotype with 45 chromosomes is a rare event, with no previous reports involving chromosomes 6p and 22q. PMID:26997945

  11. Physical Exercise, Fasting Glucose, and Renal Hyperfiltration in the General Population: The Renal Iohexol Clearance Survey in Tromsø 6 (RENIS-T6)

    PubMed Central

    Mathisen, Ulla Dorte; Eilertsen, Britt-Ann Winther; Ingebretsen, Ole C.; Jenssen, Trond; Njølstad, Inger; Solbu, Marit D.; Toft, Ingrid; Eriksen, Bjørn O.

    2012-01-01

    Summary Background and objectives Abnormally elevated GFR, or hyperfiltration, is a proposed mechanism for kidney injury in diabetes, prediabetes, and obesity. This study investigated whether lack of physical exercise is associated with hyperfiltration and whether exercise modifies the positive association between fasting glucose and measured GFR. Design, setting, participants, & measurements The Renal Iohexol Clearance Survey in Tromsø 6 measured GFR as single-sample plasma iohexol clearance in 1506 members of the general population (age 50–62 years) without diabetes, cardiovascular disease, or kidney disease. Leisure-time physical exercise was assessed by a self-administered questionnaire. Hyperfiltration was defined as GFR above the 90th percentile after adjustment for sex, age, weight, height, and use of renin-angiotensin system inhibitors. Results High-intensity exercise was associated with lower adjusted odds of hyperfiltration in men (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.28–0.80) but not in women (OR, 1.02; 95% CI, 0.60–1.72). In both sexes, high-intensity exercise modified the association between fasting glucose and GFR. A fasting glucose level 1 mmol/L higher was associated with a GFR that was 7.3 (95% CI, 4.0–10.6) and 6.2 (95% CI, 3.4–9.0) ml/min per 1.73 m2 higher in men and women who never exercised or exercised with low intensity. There was no association between fasting glucose and GFR in men and women who exercised with high intensity (interaction, P<0.001). Conclusions High-intensity exercise was associated with lower odds of hyperfiltration in men and modified the association between glucose and GFR of both sexes in a population without diabetes. PMID:22917703

  12. 22q11.2 Deletion Syndrome due to a Translocation t(6;22) in a Patient Conceived via in vitro Fertilization.

    PubMed

    Gollo Dantas, Anelisa; Bortolai, Adriana; Moysés-Oliveira, Mariana; Takeno Herrero, Sylvia; Azoubel Antunes, Adriana; Tavares Costa-Carvalho, Beatriz; Ayres Meloni, Vera; Melaragno, Maria Isabel

    2016-02-01

    We report on a patient conceived via in vitro fertilization (IVF) with a 22q11.2 deletion due to an unusual unbalanced translocation involving chromosomes 6 and 22 in a karyotype with 45 chromosomes. Cytogenomic studies showed that the patient has a 3.3-Mb deletion of chromosome 22q and a 0.4-Mb deletion of chromosome 6p, which resulted in haploinsufficiency of the genes responsible for the 22q11.2 deletion syndrome and also of the IRF4 gene, a member of the interferon regulatory factor family of transcription factors, which is expressed in the immune system cells. The rearrangement could be due to the manipulation of the embryo or as a sporadic event unrelated to IVF. Translocation involving chromosome 22 in a karyotype with 45 chromosomes is a rare event, with no previous reports involving chromosomes 6p and 22q. PMID:26997945

  13. NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR LABORATORY ASSISTANT TRAINING PLAN--GENERAL (UA-T-6.0)

    EPA Science Inventory

    The purpose of this SOP is to describe the training sequence of incoming student laboratory assistants. The procedure is designed to provide them with an overview of the project in terms of project goals, structure, and laboratory needs. This overview familiarizes the student l...

  14. Modelisation numerique des phenomenes physiques du soudage par friction-malaxage et comportement en fatigue de joints soudes en aluminium 7075-T6

    NASA Astrophysics Data System (ADS)

    Gemme, Frederic

    The aim of the present research project is to increase the amount of fundamental knowledge regarding the process by getting a better understanding of the physical phenomena involved in friction stir welding (FSW). Such knowledge is required to improve the process in the context of industrial applications. In order to do so, the first part of the project is dedicated to a theoretical study of the process, while the microstructure and the mechanical properties of welded joints obtained in different welding conditions are measured and analyzed in the second part. The combination of the tool rotating and translating movements induces plastic deformation and heat generation of the welded material. The material thermomechanical history is responsible for metallurgical phenomena occurring during FSW such as recrystallization and precipitate dissolution and coarsening. Process modelling is used to reproduce this thermomechanical history in order to predict the influence of welding on the material microstructure. It is helpful to study heat generation and heat conduction mechanisms and to understand how joint properties are related to them. In the current work, a finite element numerical model based on solid mechanics has been developed to compute the thermomechanical history of the welded material. The computation results were compared to reference experimental data in order to validate the model and to calibrate unknown physical parameters. The model was used to study the effect of the friction coefficient on the thermomechanical history. Results showed that contact conditions at the workpiece/tool interface have a strong effect on relative amounts of heat generated by friction and by plastic deformation. The comparison with the experimental torque applied by the tool for different rotational speeds has shown that the friction coefficient decreases when the rotational speed increases. Consequently, heat generation is far more important near the material/tool interface and the material deformation is shallower, increasing the lack of penetration probability. The variation of thermomechanical conditions with regards to the rotational speed is responsible for the variation of the nugget shape, as recrystallization conditions are not reached in the same volume of material. The second part of the research project was dedicated to a characterization of the welded joints microstructure and mechanical properties. Sound joints were obtained by using a manufacturing procedure involving process parameters optimization and quality control of the joint integrity. Five different combinations of rotational and advancing speeds were studied. Microstructure observations have shown that the rotational speed has an effect on recrystallization conditions because of the variation of the contact conditions at the material/tool interface. On the other hand, the advancing speed has a strong effect on the precipitation state in the heat affected zone (HAZ). The heat input increases when the advancing speed decreases. The material softening in the HAZ is then more pronounced. Mechanical testing of the welded joints showed that the fatigue resistance increases when the rotational speed increases and the advancing speed decreases. The fatigue resistance of FSW joints mainly depends on the ratio of the advancing speed on the rotational speed, called the welding pitch k. When the welding pitch is high (k ≥ 0,66 mm/rev), the fatigue resistance depends on crack initiation at the root of circular grooves left by the tool on the weld surface. The size of these grooves is directly related to the welding pitch. When the welding pitch is low (k ≤ 0,2 mm/rev), the heat input is high and the fatigue resistance is limited by the HAZ softening. The fatigue resistance is optimized when k stands in the 0,25-0,30 mm/rev range. Outside that range, the presence of small lateral lips is critical. The results of the characterization part of the project showed that the effects of the applied vertical force on the formation of lateral lips should be submitted to further investigations. The elimination of the lateral lip, which could be achieved with a more precise adjustment of the vertical force, could lead to an improved fatigue resistance. The elimination of lateral lips, but also the circular grooves left by the tool, may be obtained by developing an appropriate surfacing technique and could lead to an improved fatigue resistance without reducing the advancing speed. (Abstract shortened by UMI.)

  15. Draft Genome Sequence of Pseudomonas azotifigens Strain DSM 17556T (6H33bT), a Nitrogen Fixer Strain Isolated from a Compost Pile

    PubMed Central

    Busquets, Antonio; Peña, Arantxa; Gomila, Margarita; Mulet, Magdalena; Mayol, Joan; García-Valdés, Elena; Bennasar, Antonio; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Palaniappan, Krishnaveni; Ivanova, Natalia; Schaumberg, Andrew; Pati, Amrita; Reddy, T. B. K.; Nordberg, Henrik; Woyke, Tanja; Klenk, Hans-Peter; Kyrpides, Nikos

    2013-01-01

    Pseudomonas azotifigens strain 6H33bT is a nitrogen fixer isolated from a hyperthermal compost pile in 2005 by Hatayama and collaborators. Here we report the draft genome, which has an estimated size of 5.0 Mb, exhibits an average G+C content of 66.73%, and is predicted to encode 4,536 protein-coding genes and 100 RNA genes. PMID:24179119

  16. Spin Forming of an Aluminum 2219-T6 Aft Bulkhead for the Orion Multi-Purpose Crew Vehicle: Phase II Supplemental Report

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Squire, Michael D.; Domack, Marcia S.; Hoffman, Eric K.

    2015-01-01

    The principal focus of this project was to assist the Orion Multi-Purpose Crew Vehicle (MPCV) Program in developing a spin forming fabrication process for manufacture of the aft bulkhead of the pressure vessel. The spin forming process will enable a single piece aluminum (Al) 2219 aft bulkhead which will eliminate the current multiple piece welded construction, simplify fabrication, and lead to an enhanced design that will reduce vehicle weight by eliminating welds. Phase I of this assessment explored spin forming the single-piece forward pressure vessel bulkhead from aluminum-lithium 2195.

  17. 7-Deaza-2′-deoxyadenosine and 3-deaza-2′-deoxyadenosine replacing dA within d(A6)-tracts: differential bending at 3′- and 5′-junctions of d(A6)·d(T6) and B-DNA

    PubMed Central

    Seela, Frank; Grein, Thomas

    1992-01-01

    7-Deaza-2′-deoxyadenosine (1, c7Ad) and 3-deaza-2′-deoxyadenosine (2, c3Ad) have been incorporated into d(AAAAAA) tracts replacing dA at various positions within oligonucleotides. For this purpose suitably protected phosphonates have been prepared and oligonucleotides were synthsized on solid-phase. The oligomers were hybridized with their cognate strands. The duplexes were phosphorylated at OH-5′ by polynucleotide kinase and self-ligated to multimers employing T4 DNA ligase. Oligomerized DNA-fragments were analyzed by polyacrylamide gel electrophoresis and the bending was determined from anomalies of electrophoretic mobility. Replacement of dA by c3Ad decreased the bending more than replacement by c7Ad. Reduction of bending was much stronger when the modified nucleosides replaced one or several dA residues at the 3′-site of an d(AAAAAA)-tract whereas replacement at the 5′-site showed no significant influence [1, 2]. Images PMID:1630898

  18. Established Microbial Colonies Can Survive Type VI Secretion Assault

    PubMed Central

    Borenstein, David Bruce; Ringel, Peter; Basler, Marek; Wingreen, Ned S.

    2015-01-01

    Type VI secretion (T6S) is a cell-to-cell injection system that can be used as a microbial weapon. T6S kills vulnerable cells, and is present in close to 25% of sequenced Gram-negative bacteria. To examine the ecological role of T6S among bacteria, we competed self-immune T6S+ cells and T6S-sensitive cells in simulated range expansions. As killing takes place only at the interface between sensitive and T6S+ strains, while growth takes place everywhere, sufficiently large domains of sensitive cells can achieve net growth in the face of attack. Indeed T6S-sensitive cells can often outgrow their T6S+ competitors. We validated these findings through in vivo competition experiments between T6S+ Vibrio cholerae and T6S-sensitive Escherichia coli. We found that E. coli can survive and even dominate so long as they have an adequate opportunity to form microcolonies at the outset of the competition. Finally, in simulated competitions between two equivalent and mutually sensitive T6S+ strains, the more numerous strain has an advantage that increases with the T6S attack rate. We conclude that sufficiently large domains of T6S-sensitive individuals can survive attack and potentially outcompete self-immune T6S+ bacteria. PMID:26485125

  19. Comparative genomics of type VI secretion systems in strains of Pantoea ananatis from different environments

    PubMed Central

    2014-01-01

    Background The Type VI secretion system (T6SS) has been identified in several different bacteria, including the plant pathogenPantoea ananatis. Previous in silico analyses described three different T6SS loci present in the pathogenic strain of P. ananatis LMG 20103. This initial investigation has been extended to include an additional seven sequenced strains of P. ananatis together with 39 strains from different ecological niches. Comparative and phylogenetic analyses were used to investigate the distribution, evolution, intra-strain variability and operon structure of the T6SS in the sequenced strains. Results Three different T6SS loci were identified in P. ananatis strain LMG 20103 and designated PA T6SS 1-3. PA T6SS-1 was present in all sequenced strains of P. ananatis and in all 39 additional strains examined in this study. In addition, PA T6SS-1 included all 13 core T6SS genes required for synthesis of a functional T6SS. The plasmid-borne PA T6SS-2 also included all 13 core T6SS genes but was restricted to only 33% (15/46) of the strains examined. In addition, PA T6SS-2 was restricted to strains of P. ananatis isolated from symptomatic plant material. This finding raises the possibility of an association between PA T6SS-2 and either pathogenicity or host specificity. The third cluster PA T6SS-3 was present in all strains analyzed in this study but lacked 11 of the 13 core T6SS genes suggesting it may not encoded a functional T6SS. Inter-strain variability was also associated with hcp and vgrG islands, which are associated with the T6SS and encode a variable number of proteins usually of unknown function. These proteins may play a role in the fitness of different strains in a variety of ecological niches or as candidate T6SS effectors. Phylogenetic analysis indicated that PA T6SS-1 and PA T6SS-2 are evolutionarily distinct. Conclusion Our analysis indicates that the three T6SSs of P. ananatis appear to have been independently acquired and may play different

  20. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... for DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180 Transportation... Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure. Each facility performing eddy... ring and probe for each DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must...

  1. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... for DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180 Transportation... Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure. Each facility performing eddy... ring and probe for each DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must...

  2. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... for DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180 Transportation... Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure. Each facility performing eddy... ring and probe for each DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must...

  3. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... for DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180 Transportation... Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure. Each facility performing eddy... ring and probe for each DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must...

  4. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... for DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180 Transportation... Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure. Each facility performing eddy... ring and probe for each DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must...

  5. Only one of the two type VI secretion systems encoded in the Salmonella enterica serotype Dublin genome is involved in colonization of the avian and murine hosts.

    PubMed

    Pezoa, David; Blondel, Carlos J; Silva, Cecilia A; Yang, Hee-Jeong; Andrews-Polymenis, Helene; Santiviago, Carlos A; Contreras, Inés

    2014-01-01

    The type VI secretion system (T6SS) is a virulence factor for many Gram-negative bacteria. Salmonella genus harbors five phylogenetically distinct T6SS loci encoded in Salmonella Pathogenicity Islands (SPIs) SPI-6, SPI-19, SPI-20, SPI-21 and SPI-22, which are differentially distributed among serotypes. The T6SSs encoded in SPI-6 and SPI-19 contribute to pathogenesis of serotypes Typhimurium and Gallinarum in mice and chickens, respectively. Salmonella Dublin is a pathogen restricted to cattle where it causes a systemic disease. Also, it can colonize other hosts such as chickens and mice, which can act as reservoirs of this serotype. Salmonella Dublin harbors the genes for both T6SS(SPI-6) and T6SS(SPI-19). This study has determined the contribution of T6SS(SPI-6) and T6SS(SPI-19) to host-colonization by Salmonella Dublin using avian and murine models of infection. Competitive index experiments showed that, a mutant strain lacking both T6SSs (∆T6SS(SPI-6)/∆T6SS(SPI-19)) presents a strong colonization defect in cecum of chickens, similar to the defect observed for the ∆T6SS(SPI-6) mutant, suggesting that this serotype requires a functional T6SS(SPI-6) for efficient colonization of the avian gastrointestinal tract. Colonization of mice was also defective, although to a lesser extent than in chickens. In contrast, the T6SS(SPI-19) was not necessary for colonization of either chickens or mice. Transfer of T6SS(SPI-6), but not T6SS(SPI-19), restored the ability of the double mutant to colonize both animal hosts. Our data indicate that Salmonella Dublin requires only the T6SS(SPI-6) for efficient colonization of mice and chickens, and that the T6SS(SPI-6) and T6SS(SPI-19) are not functionally redundant. PMID:24405577

  6. H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing

    PubMed Central

    Brunet, Yannick R.; Khodr, Ahmad; Logger, Laureen; Aussel, Laurent; Mignot, Tâm; Rimsky, Sylvie

    2015-01-01

    The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of the S. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will help S. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection. PMID:25916986

  7. H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing.

    PubMed

    Brunet, Yannick R; Khodr, Ahmad; Logger, Laureen; Aussel, Laurent; Mignot, Tâm; Rimsky, Sylvie; Cascales, Eric

    2015-07-01

    The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of the S. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will help S. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection. PMID:25916986

  8. Bile Salts Modulate the Mucin-Activated Type VI Secretion System of Pandemic Vibrio cholerae

    PubMed Central

    Unterweger, Daniel; Diaz-Satizabal, Laura; Ogg, Stephen; Pukatzki, Stefan

    2015-01-01

    The causative agent of cholera, Vibrio cholerae, regulates its diverse virulence factors to thrive in the human small intestine and environmental reservoirs. Among this pathogen’s arsenal of virulence factors is the tightly regulated type VI secretion system (T6SS). This system acts as an inverted bacteriophage to inject toxins into competing bacteria and eukaryotic phagocytes. V. cholerae strains responsible for the current 7th pandemic activate their T6SS within the host. We established that T6SS-mediated competition occurs upon T6SS activation in the infant mouse, and that this system is functional under anaerobic conditions. When investigating the intestinal host factors mucins (a glycoprotein component of mucus) and bile for potential regulatory roles in controlling the T6SS, we discovered that once mucins activate the T6SS, bile acids can further modulate T6SS activity. Microbiota modify bile acids to inhibit T6SS-mediated killing of commensal bacteria. This interplay is a novel interaction between commensal bacteria, host factors, and the V. cholerae T6SS, showing an active host role in infection. PMID:26317760

  9. Monotonic and cyclic fatigue properties of automotive aluminum alloys

    SciTech Connect

    Wong, W.A.

    1984-01-01

    Monotonic and strain-controlled fatigue tests were conducted on 2014-T6, 6061-T6 and 7175-T73 hand-forgings, 5052-H32 and 6061-T6 sheet, and a 1983/84 production Chevrolet Corvette upper-control-arm-pivot shaft (UCAPS) cold-forged from 5454-H12 and 6061-T4 rolled rod (the 6061 UCAPS was artificially-aged to the -T6 temper, after forging). Various monotonic and cyclic fatigue stress-strain material properties are presented. The responses of the various alloys and product-forms in terms of cyclic hardening or softening are described.

  10. Some observations on loss of static strength due to fatigue cracks

    NASA Technical Reports Server (NTRS)

    Illg, Walter; Hardrath, Herbert F

    1955-01-01

    Static tensile tests were performed on simple notched specimens containing fatigue cracks. Four types of aluminum alloys were investigated: 2024-T3(formerly 24S-T3) and 7075-T6(formerly 75S-T6) in sheet form, and 2024-T4(formerly 24S-T4) and 7075-T6(formerly 75S-T6) in extruded form. The cracked specimens were tested statically under four conditions: unmodified and with reduced eccentricity of loading by three methods. Results of static tests on C-46 wings containing fatigue cracks are also reported.

  11. Two functional type VI secretion systems in avian pathogenic Escherichia coli are involved in different pathogenic pathways.

    PubMed

    Ma, Jiale; Bao, Yinli; Sun, Min; Dong, Wenyang; Pan, Zihao; Zhang, Wei; Lu, Chengping; Yao, Huochun

    2014-09-01

    Type VI secretion systems (T6SSs) are involved in the pathogenicity of several Gram-negative bacteria. The VgrG protein, a core component and effector of T6SS, has been demonstrated to perform diverse functions. The N-terminal domain of VgrG protein is a homologue of tail fiber protein gp27 of phage T4, which performs a receptor binding function and determines the host specificity. Based on sequence analysis, we found that two putative T6SS loci exist in the genome of the avian pathogenic Escherichia coli (APEC) strain TW-XM. To assess the contribution of these two T6SSs to TW-XM pathogenesis, the crucial clpV clusters of these two T6SS loci and their vgrG genes were deleted to generate a series of mutants. Consequently, T6SS1-associated mutants presented diminished adherence to and invasion of several host cell lines cultured in vitro, decreased pathogenicity in duck and mouse infection models in vivo, and decreased biofilm formation and bacterial competitive advantage. In contrast, T6SS2-associated mutants presented a significant decrease only in the adherence to and invasion of mouse brain microvascular endothelial cell (BMEC) line bEnd.3 and brain tissue of the duck infection model. These results suggested that T6SS1 was involved in the proliferation of APEC in systemic infection, whereas VgrG-T6SS2 was responsible only for cerebral infection. Further study demonstrated that VgrG-T6SS2 was able to bind to the surface of bEnd.3 cells, whereas it did not bind to DF-1 (chicken embryo fibroblast) cells, which further proved the interaction of VgrG-T6SS2 with the surface of BMECs. PMID:24980972

  12. Type VI Secretion System Transports Zn2+ to Combat Multiple Stresses and Host Immunity

    PubMed Central

    Zhu, Wenhan; Gao, Fen; Wang, Yao; Zhang, Lei; Zhang, Weipeng; Wei, Gehong; Luo, Zhao-Qing; Shen, Xihui

    2015-01-01

    Type VI secretion systems (T6SSs) are widespread multi-component machineries that translocate effectors into either eukaryotic or prokaryotic cells, for virulence or for interbacterial competition. Herein, we report that the T6SS-4 from Yersinia pseudotuberculosis displays an unexpected function in the transportation of Zn2+ to combat diverse stresses and host immunity. Environmental insults such as oxidative stress induce the expression of T6SS-4 via OxyR, the transcriptional factor that also regulates many oxidative response genes. Zinc transportation is achieved by T6SS-4-mediated translocation of a novel Zn2+-binding protein substrate YezP (YPK_3549), which has the capacity to rescue the sensitivity to oxidative stress exhibited by T6SS-4 mutants when added to extracellular milieu. Disruption of the classic zinc transporter ZnuABC together with T6SS-4 or yezP results in mutants that almost completely lost virulence against mice, further highlighting the importance of T6SS-4 in resistance to host immunity. These results assigned an unconventional role to T6SSs, which will lay the foundation for studying novel mechanisms of metal ion uptake by bacteria and the role of this process in their resistance to host immunity and survival in harmful environments. PMID:26134274

  13. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  14. The Versatile Type VI Secretion System

    PubMed Central

    Alteri, Christopher J.; Mobley, Harry L.T.

    2016-01-01

    Summary Bacterial Type VI Secretion Systems (T6SS) function as contractile nanomachines to puncture target cells and deliver lethal effectors. In the ten years since the discovery of the T6SS, much has been learned about the structure and function of this versatile protein secretion apparatus. Most of the conserved protein components that comprise the T6SS apparatus itself have been identified and ascribed specific functions. In addition, numerous effector proteins that are translocated by the T6SS have been identified and characterized. These protein effectors usually represent toxic cargoes that are delivered by the attacker cell to a target cell. The field is beginning to better understand the lifestyle or physiology that dictates when bacteria normally express their T6SS. In this Chapter, we consider what is known about the structure and regulation of the T6SS, the numerous classes of antibacterial effector T6SS substrates, and how the action of the T6SS relates to a given lifestyle or behavior in certain bacteria. PMID:27227310

  15. Independent Regulation of Type VI Secretion in Vibrio cholerae by TfoX and TfoY.

    PubMed

    Metzger, Lisa C; Stutzmann, Sandrine; Scrignari, Tiziana; Van der Henst, Charles; Matthey, Noémie; Blokesch, Melanie

    2016-05-01

    Type VI secretion systems (T6SSs) are nanomachines used for interbacterial killing and intoxication of eukaryotes. Although Vibrio cholerae is a model organism for structural studies on T6SSs, the underlying regulatory network is less understood. A recent study showed that the T6SS is part of the natural competence regulon in V. cholerae and is activated by the regulator TfoX. Here, we identify the TfoX homolog TfoY as a second activator of the T6SS. Importantly, despite inducing the same T6SS core machinery, the overall regulons differ significantly for TfoX and TfoY. We show that TfoY does not contribute to competence induction. Instead, TfoY drives the production of T6SS-dependent and T6SS-independent toxins, together with an increased motility phenotype. Hence, we conclude that V. cholerae uses its sole T6SS in response to diverse cues and for distinctive outcomes: either to kill for the prey's DNA, leading to horizontal gene transfer, or as part of a defensive escape reaction. PMID:27117415

  16. Metabolic phenotypes of Saccharomyces cerevisiae mutants with altered trehalose 6-phosphate dynamics.

    PubMed

    Walther, Thomas; Mtimet, Narjes; Alkim, Ceren; Vax, Amélie; Loret, Marie-Odile; Ullah, Azmat; Gancedo, Carlos; Smits, Gertien J; François, Jean Marie

    2013-09-01

    In Saccharomyces cerevisiae, synthesis of T6P (trehalose 6-phosphate) is essential for growth on most fermentable carbon sources. In the present study, the metabolic response to glucose was analysed in mutants with different capacities to accumulate T6P. A mutant carrying a deletion in the T6P synthase encoding gene, TPS1, which had no measurable T6P, exhibited impaired ethanol production, showed diminished plasma membrane H⁺-ATPase activation, and became rapidly depleted of nearly all adenine nucleotides which were irreversibly converted into inosine. Deletion of the AMP deaminase encoding gene, AMD1, in the tps1 strain prevented inosine formation, but did not rescue energy balance or growth on glucose. Neither the 90%-reduced T6P content observed in a tps1 mutant expressing the Tps1 protein from Yarrowia lipolytica, nor the hyperaccumulation of T6P in the tps2 mutant had significant effects on fermentation rates, growth on fermentable carbon sources or plasma membrane H⁺-ATPase activation. However, intracellular metabolite dynamics and pH homoeostasis were strongly affected by changes in T6P concentrations. Hyperaccumulation of T6P in the tps2 mutant caused an increase in cytosolic pH and strongly reduced growth rates on non-fermentable carbon sources, emphasizing the crucial role of the trehalose pathway in the regulation of respiratory and fermentative metabolism. PMID:23763276

  17. Independent Regulation of Type VI Secretion in Vibrio cholerae by TfoX and TfoY

    PubMed Central

    Metzger, Lisa C.; Stutzmann, Sandrine; Scrignari, Tiziana; Van der Henst, Charles; Matthey, Noémie; Blokesch, Melanie

    2016-01-01

    Summary Type VI secretion systems (T6SSs) are nanomachines used for interbacterial killing and intoxication of eukaryotes. Although Vibrio cholerae is a model organism for structural studies on T6SSs, the underlying regulatory network is less understood. A recent study showed that the T6SS is part of the natural competence regulon in V. cholerae and is activated by the regulator TfoX. Here, we identify the TfoX homolog TfoY as a second activator of the T6SS. Importantly, despite inducing the same T6SS core machinery, the overall regulons differ significantly for TfoX and TfoY. We show that TfoY does not contribute to competence induction. Instead, TfoY drives the production of T6SS-dependent and T6SS-independent toxins, together with an increased motility phenotype. Hence, we conclude that V. cholerae uses its sole T6SS in response to diverse cues and for distinctive outcomes: either to kill for the prey’s DNA, leading to horizontal gene transfer, or as part of a defensive escape reaction. PMID:27117415

  18. 27 CFR 9.230 - Ballard Canyon.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Los Olivos map, to a marked, unnamed large structure located within a circular-shaped 920-foot contour... located within the 760-foot contour line, T6N/R31W; then (7) Proceed west-southwesterly in a straight line... intersection with the 400-foot contour line, T6N/R31W; then (10) Proceed southerly and then northwesterly...

  19. The Type VI secretion system - a widespread and versatile cell targeting system.

    PubMed

    Coulthurst, Sarah J

    2013-01-01

    The Type VI secretion system (T6SS) is the most recently described of the Gram-negative bacterial secretion systems and is widely distributed amongst diverse species. T6SSs are currently believed to be complex molecular machines which inject effector proteins into target cells and which incorporate a bacteriophage-like cell-puncturing device. T6SSs have been implicated in eukaryotic cell targeting and virulence in a range of important pathogens. More recently, 'antibacterial' T6SSs have been reported, which are used to efficiently target competitor bacterial cells by the injection of antibacterial toxins. Although it is clear that T6SSs can be deployed as versatile weapons to compete with other bacteria or attack simple or higher eukaryotes, much remains to be determined about this intriguing system. PMID:23542428

  20. Biochemical analysis of TssK, a core component of the bacterial Type VI secretion system, reveals distinct oligomeric states of TssK and identifies a TssK–TssFG subcomplex

    PubMed Central

    English, Grant; Byron, Olwyn; Cianfanelli, Francesca R.; Prescott, Alan R.; Coulthurst, Sarah J.

    2014-01-01

    Gram-negative bacteria use the Type VI secretion system (T6SS) to inject toxic proteins into rival bacteria or eukaryotic cells. However, the mechanism of the T6SS is incompletely understood. In the present study, we investigated a conserved component of the T6SS, TssK, using the antibacterial T6SS of Serratia marcescens as a model system. TssK was confirmed to be essential for effector secretion by the T6SS. The native protein, although not an integral membrane protein, appeared to localize to the inner membrane, consistent with its presence within a membrane-anchored assembly. Recombinant TssK purified from S. marcescens was found to exist in several stable oligomeric forms, namely trimer, hexamer and higher-order species. Native-level purification of TssK identified TssF and TssG as interacting proteins. TssF and TssG, conserved T6SS components of unknown function, were required for T6SS activity, but not for correct localization of TssK. A complex containing TssK, TssF and TssG was subsequently purified in vitro, confirming that these three proteins form a new subcomplex within the T6SS. Our findings provide new insight into the T6SS assembly, allowing us to propose a model whereby TssK recruits TssFG into the membrane-associated T6SS complex and different oligomeric states of TssK may contribute to the dynamic mechanism of the system. PMID:24779861

  1. Biochemical analysis of TssK, a core component of the bacterial Type VI secretion system, reveals distinct oligomeric states of TssK and identifies a TssK-TssFG subcomplex.

    PubMed

    English, Grant; Byron, Olwyn; Cianfanelli, Francesca R; Prescott, Alan R; Coulthurst, Sarah J

    2014-07-15

    Gram-negative bacteria use the Type VI secretion system (T6SS) to inject toxic proteins into rival bacteria or eukaryotic cells. However, the mechanism of the T6SS is incompletely understood. In the present study, we investigated a conserved component of the T6SS, TssK, using the antibacterial T6SS of Serratia marcescens as a model system. TssK was confirmed to be essential for effector secretion by the T6SS. The native protein, although not an integral membrane protein, appeared to localize to the inner membrane, consistent with its presence within a membrane-anchored assembly. Recombinant TssK purified from S. marcescens was found to exist in several stable oligomeric forms, namely trimer, hexamer and higher-order species. Native-level purification of TssK identified TssF and TssG as interacting proteins. TssF and TssG, conserved T6SS components of unknown function, were required for T6SS activity, but not for correct localization of TssK. A complex containing TssK, TssF and TssG was subsequently purified in vitro, confirming that these three proteins form a new subcomplex within the T6SS. Our findings provide new insight into the T6SS assembly, allowing us to propose a model whereby TssK recruits TssFG into the membrane-associated T6SS complex and different oligomeric states of TssK may contribute to the dynamic mechanism of the system. PMID:24779861

  2. Discovery of the β-barrel–type RNA methyltransferase responsible for N6-methylation of N6-threonylcarbamoyladenosine in tRNAs

    PubMed Central

    Kimura, Satoshi; Miyauchi, Kenjyo; Ikeuchi, Yoshiho; Thiaville, Patrick C.; de Crécy-Lagard, Valérie; Suzuki, Tsutomu

    2014-01-01

    Methylation is a versatile reaction involved in the synthesis and modification of biologically active molecules, including RNAs. N6-methyl-threonylcarbamoyl adenosine (m6t6A) is a post-transcriptional modification found at position 37 of tRNAs from bacteria, insect, plants, and mammals. Here, we report that in Escherichia coli, yaeB (renamed as trmO) encodes a tRNA methyltransferase responsible for the N6-methyl group of m6t6A in tRNAThr specific for ACY codons. TrmO has a unique single-sheeted β-barrel structure and does not belong to any known classes of methyltransferases. Recombinant TrmO employs S-adenosyl-L-methionine (AdoMet) as a methyl donor to methylate t6A to form m6t6A in tRNAThr. Therefore, TrmO/YaeB represents a novel category of AdoMet-dependent methyltransferase (Class VIII). In a ΔtrmO strain, m6t6A was converted to cyclic t6A (ct6A), suggesting that t6A is a common precursor for both m6t6A and ct6A. Furthermore, N6-methylation of t6A enhanced the attenuation activity of the thr operon, suggesting that TrmO ensures efficient decoding of ACY. We also identified a human homolog, TRMO, indicating that m6t6A plays a general role in fine-tuning of decoding in organisms from bacteria to mammals. PMID:25063302

  3. The Type VI Secretion System Encoded in Salmonella Pathogenicity Island 19 Is Required for Salmonella enterica Serotype Gallinarum Survival within Infected Macrophages

    PubMed Central

    Blondel, Carlos J.; Jiménez, Juan C.; Leiva, Lorenzo E.; Álvarez, Sergio A.; Pinto, Bernardo I.; Contreras, Francisca; Pezoa, David; Santiviago, Carlos A.

    2013-01-01

    Salmonella enterica serotype Gallinarum is the causative agent of fowl typhoid, a disease characterized by high morbidity and mortality that causes major economic losses in poultry production. We have reported that S. Gallinarum harbors a type VI secretion system (T6SS) encoded in Salmonella pathogenicity island 19 (SPI-19) that is required for efficient colonization of chicks. In the present study, we aimed to characterize the SPI-19 T6SS functionality and to investigate the mechanisms behind the phenotypes previously observed in vivo. Expression analyses revealed that SPI-19 T6SS core components are expressed and produced under in vitro bacterial growth conditions. However, secretion of the structural/secreted components Hcp1, Hcp2, and VgrG to the culture medium could not be determined, suggesting that additional signals are required for T6SS-dependent secretion of these proteins. In vitro bacterial competition assays failed to demonstrate a role for SPI-19 T6SS in interbacterial killing. In contrast, cell culture experiments with murine and avian macrophages (RAW264.7 and HD11, respectively) revealed production of a green fluorescent protein-tagged version of VgrG soon after Salmonella uptake. Furthermore, infection of RAW264.7 and HD11 macrophages with deletion mutants of SPI-19 or strains with genes encoding specific T6SS core components (clpV and vgrG) revealed that SPI-19 T6SS contributes to S. Gallinarum survival within macrophages at 20 h postuptake. SPI-19 T6SS function was not linked to Salmonella-induced cytotoxicity or cell death of infected macrophages, as has been described for other T6SS. Our data indicate that SPI-19 T6SS corresponds to a novel tool used by Salmonella to survive within host cells. PMID:23357385

  4. Evaluation of a Yersinia pestis Mutant Impaired in a Thermoregulated Type VI-Like Secretion System in Flea, Macrophage and Murine Models

    PubMed Central

    Robinson, Jennilee B.; Telepnev, Maxim V.; Zudina, Irina V.; Bouyer, Donald; Montenieri, John A.; Bearden, Scott W.; Gage, Kenneth L.; Agar, Stacy L.; Foltz, Sheri M.; Chauhan, Sadhana; Chopra, Ashok K.; Motin, Vladimir L.

    2009-01-01

    Type VI secretion systems (T6SS) have been identified recently in several Gram-negative organisms and have been shown to be associated with virulence in some bacterial pathogens. A T6SS of Yersinia pestis CO92 (locus YPO0499-YPO0516) was deleted followed by investigation of the phenotype of this mutation. We observed that this T6SS locus of Y. pestis was preferentially expressed at 26° C in comparison to 37° C suggesting a possible role in the flea cycle. However, we found that the deletion of T6SS locus YPO0499-YPO0516 in Y. pestis CO92 had no effect on the ability of this strain to infect the oriental rat flea, Xenopsylla cheopis. Nevertheless, this mutant displayed increased intracellular numbers in macrophage-like J774.A1 cells after 20 hours postinfection for bacterial cells pre-grown at 26° C indicating that expression of this T6SS locus limited intracellular replication in macrophages. In addition, deletion of the YPO0499-YPO0516 locus reduced the uptake by macrophages of the Y. pestis mutant pre-grown at 37°C, suggesting that this T6SS locus has phagocytosis-promoting activity. Further study of the virulence of the T6SS mutant in murine bubonic and inhalation plague models revealed no attenuation in comparison with the parental CO92 strain. PMID:19716410

  5. Tensile and compressive stress-strain behavior of heat treated boron-aluminum

    NASA Technical Reports Server (NTRS)

    Kennedy, J. M.; Tenney, D. R.; Herakovich, C. T.

    1978-01-01

    An experimental study was conducted to assess the effects of heat treatment and cyclic mechanical loading on the tensile and compressive stress-strain behavior of six boron-aluminum composites having different laminate orientations and being subjected to different heat treatments. The heat treatments were as-fabricated, T6, and T6N consisting of T6 treatment followed by cryogenic quench in liquid nitrogen prior to testing. All laminates were tested in monotonic and cyclic compression, while the tensile-test data are taken from the literature for comparison purposes. It is shown that the linear elastic range of the T6- and T6N-condition specimens is larger than that of the as-fabricated specimens, and that cyclic loading in tension or compression strain hardens the specimens and extends the linear elastic range. For laminates containing 0-deg plies, the stress-strain behavior upon unloading is found to be nonlinear, whereas the other laminates exhibit a linear behavior upon unloading. Specimens in the T6 and T6N conditions show higher strain hardening than the as-fabricated specimens.

  6. Evaluation of a Yersinia pestis mutant impaired in a thermoregulated type VI-like secretion system in flea, macrophage and murine models.

    PubMed

    Robinson, Jennilee B; Telepnev, Maxim V; Zudina, Irina V; Bouyer, Donald; Montenieri, John A; Bearden, Scott W; Gage, Kenneth L; Agar, Stacy L; Foltz, Sheri M; Chauhan, Sadhana; Chopra, Ashok K; Motin, Vladimir L

    2009-11-01

    Type VI secretion systems (T6SSs) have been identified recently in several Gram-negative organisms and have been shown to be associated with virulence in some bacterial pathogens. A T6SS of Yersinia pestis CO92 (locus YPO0499-YPO0516) was deleted followed by investigation of the phenotype of this mutation. We observed that this T6SS locus of Y. pestis was preferentially expressed at 26 degrees C in comparison to 37 degrees C suggesting a possible role in the flea cycle. However, we found that the deletion of T6SS locus YPO0499-YPO0516 in Y. pestis CO92 had no effect on the ability of this strain to infect the oriental rat flea, Xenopsylla cheopis. Nevertheless, this mutant displayed increased intracellular numbers in macrophage-like J774.A1 cells after 20 h post-infection for bacterial cells pre-grown at 26 degrees C indicating that expression of this T6SS locus limited intracellular replication in macrophages. In addition, deletion of the YPO0499-YPO0516 locus reduced the uptake by macrophages of the Y. pestis mutant pre-grown at 37 degrees C, suggesting that this T6SS locus has phagocytosis-promoting activity. Further study of the virulence of the T6SS mutant in murine bubonic and inhalation plague models revealed no attenuation in comparison with the parental CO92 strain. PMID:19716410

  7. Type VI Secretion System Toxins Horizontally Shared between Marine Bacteria

    PubMed Central

    Salomon, Dor; Klimko, John A.; Trudgian, David C.; Kinch, Lisa N.; Grishin, Nick V.; Mirzaei, Hamid; Orth, Kim

    2015-01-01

    The type VI secretion system (T6SS) is a widespread protein secretion apparatus used by Gram-negative bacteria to deliver toxic effector proteins into adjacent bacterial or host cells. Here, we uncovered a role in interbacterial competition for the two T6SSs encoded by the marine pathogen Vibrio alginolyticus. Using comparative proteomics and genetics, we identified their effector repertoires. In addition to the previously described effector V12G01_02265, we identified three new effectors secreted by T6SS1, indicating that the T6SS1 secretes at least four antibacterial effectors, of which three are members of the MIX-effector class. We also showed that the T6SS2 secretes at least three antibacterial effectors. Our findings revealed that many MIX-effectors belonging to clan V are “orphan” effectors that neighbor mobile elements and are shared between marine bacteria via horizontal gene transfer. We demonstrated that a MIX V-effector from V. alginolyticus is a functional T6SS effector when ectopically expressed in another Vibrio species. We propose that mobile MIX V-effectors serve as an environmental reservoir of T6SS effectors that are shared and used to diversify antibacterial toxin repertoires in marine bacteria, resulting in enhanced competitive fitness. PMID:26305100

  8. Structure/property relations of aluminum under varying rates and stress states

    SciTech Connect

    Tucker, Matthew T; Horstemeyer, Mark F; Whittington, Wilburn R; Solanki, Kiran N

    2010-11-19

    In this work we analyze the plasticity, damage, and fracture characteristics of three different processed aluminum alloys (rolled 5083-H13, cast A356-T6, and extruded 6061-T6) under varying stress states (tension, compression, and torsion) and strain rates (0.001/, 1/s., and 1000/s). The stress state difference had more of a flow stress effect than the applied strain rates for those given in this study (0.001/sec up to 1000/sec). The stress state and strain rate also had a profound effect on the damage evolution of each aluminum alloy. Tension and torsional straining gave much greater damage nucleation rates than compression. Although the damage of all three alloys was found to be void nucleation dominated, the A356-T6 and 5083-H131 aluminum alloys incurred void damage via micron scale particles where the 6061-T6 aluminum alloy incurred void damage from two scales, micron-scale particles and nanoscale precipitates. Having two length scales of particles that participated in the damage evolution made the 6061-T6 incur a strain rate sensitive damage rate that was different than the other two aluminum alloys. Under tension, as the strain rate increased, the 6061-T6 aluminum alloy's void nucleation rate decreased, but the A356-T6 and 5083-H131 aluminum alloys void nucleation rate increased.

  9. An ERP study of good production vis-à-vis poor perception of tones in Cantonese: implications for top-down speech processing.

    PubMed

    Law, Sam-Po; Fung, Roxana; Kung, Carmen

    2013-01-01

    This study investigated a theoretically challenging dissociation between good production and poor perception of tones among neurologically unimpaired native speakers of Cantonese. The dissociation is referred to as the near-merger phenomenon in sociolinguistic studies of sound change. In a passive oddball paradigm, lexical and nonlexical syllables of the T1/T6 and T4/T6 contrasts were presented to elicit the mismatch negativity (MMN) and P3a from two groups of participants, those who could produce and distinguish all tones in the language (Control) and those who could produce all tones but specifically failed to distinguish between T4 and T6 in perception (Dissociation). The presence of MMN to T1/T6 and null response to T4/T6 of lexical syllables in the dissociation group confirmed the near-merger phenomenon. The observation that the control participants exhibited a statistically reliable MMN to lexical syllables of T1/T6, weaker responses to nonlexical syllables of T1/T6 and lexical syllables of T4/T6, and finally null response to nonlexical syllables of T4/T6, suggests the involvement of top-down processing in speech perception. Furthermore, the stronger P3a response of the control group, compared with the dissociation group in the same experimental conditions, may be taken to indicate higher cognitive capability in attention switching, auditory attention or memory in the control participants. This cognitive difference, together with our speculation that constant top-down predictions without complete bottom-up analysis of acoustic signals in speech recognition may reduce one's sensitivity to small acoustic contrasts, account for the occurrence of dissociation in some individuals but not others. PMID:23342146

  10. An ERP Study of Good Production vis-à-vis Poor Perception of Tones in Cantonese: Implications for Top-Down Speech Processing

    PubMed Central

    Law, Sam-Po; Fung, Roxana; Kung, Carmen

    2013-01-01

    This study investigated a theoretically challenging dissociation between good production and poor perception of tones among neurologically unimpaired native speakers of Cantonese. The dissociation is referred to as the near-merger phenomenon in sociolinguistic studies of sound change. In a passive oddball paradigm, lexical and nonlexical syllables of the T1/T6 and T4/T6 contrasts were presented to elicit the mismatch negativity (MMN) and P3a from two groups of participants, those who could produce and distinguish all tones in the language (Control) and those who could produce all tones but specifically failed to distinguish between T4 and T6 in perception (Dissociation). The presence of MMN to T1/T6 and null response to T4/T6 of lexical syllables in the dissociation group confirmed the near-merger phenomenon. The observation that the control participants exhibited a statistically reliable MMN to lexical syllables of T1/T6, weaker responses to nonlexical syllables of T1/T6 and lexical syllables of T4/T6, and finally null response to nonlexical syllables of T4/T6, suggests the involvement of top-down processing in speech perception. Furthermore, the stronger P3a response of the control group, compared with the dissociation group in the same experimental conditions, may be taken to indicate higher cognitive capability in attention switching, auditory attention or memory in the control participants. This cognitive difference, together with our speculation that constant top-down predictions without complete bottom-up analysis of acoustic signals in speech recognition may reduce one’s sensitivity to small acoustic contrasts, account for the occurrence of dissociation in some individuals but not others. PMID:23342146

  11. Spectral and electrochemical detection of protonated triplex formation by a small-molecule anticancer agent

    NASA Astrophysics Data System (ADS)

    Feng, Lingyan; Li, Xi; Peng, Yinghua; Geng, Jie; Ren, Jinsong; Qu, Xiaogang

    2009-10-01

    Triplex helical formation has been the focus of considerable interest because of possible applications in developing new molecular biology tools as well as therapeutic agents and the possible relevance of H-DNA structures in biology system. We report here that a small-molecule anticancer agent, coralyne, has binding preference to the less stable protonated triplex d(C +-T) 6:d(A-G) 6·d(C-T) 6 over duplex d(A-G) 6·d(C-T) 6 and shows different spectral and electrochemical characteristics when binding to triplex and duplex DNA, indicating that electrochemical technique can detect the less stable protonated triplex formation.

  12. Ordering of a prototypical conjugated molecular system during monolayer growth on the (1×2)-Au(110) surface

    NASA Astrophysics Data System (ADS)

    Nardelli, M. Buongiorno; Cvetko, D.; de Renzi, V.; Floreano, L.; Gotter, R.; Morgante, A.; Peloi, M.; Tommasini, F.; Danieli, R.; Rossini, S.; Taliani, C.; Zamboni, R.

    1996-01-01

    The UHV deposition of α-hexathiophene (T6) oligomers on the 1×2 reconstructed Au(110) surface has been studied in situ. The evolution of the surface morphology during the deposition is followed by the He atom scattering method. A proliferation of Au monoatomic steps is observed during deposition, indicating a strong interaction between Au substrate and T6 molecules. The build-up of a well-ordered single monolayer is obtained with a rectangular unit cell. Its dimensions indicate that T6 molecules lie on the surface, aligned along the rows of close-packed Au atoms.

  13. Oceanobacillus-like bacterium isolated from Vyhna travertine spring.

    PubMed

    Pristas, P; Cunderlikova, M; Judova, J

    2014-03-01

    During characterization of autochthonic Vyhna travertine source microflora, several bacterial strains were isolated and characterised. Isolate T6, a halotolerant, moderately alkaliphilic and thermophilic bacterial isolate, was further characterised based on physiological, microbiological and biochemical tests and phylogenetic 16S rRNA analysis. On the basis of the results obtained, the T6 isolate should be placed in the genus Oceanobacillus, and it is probably a prototype of a novel bacterial species. Characterization of the T6 isolate broadens our knowledge on variability of halophilic bacteria of Oceanobacillus genus and expands data on travertine-associated bacterial communities. PMID:24022266

  14. Effects of Initial Temper Condition and Postweld Heat Treatment on the Properties of Dissimilar Friction-Stir-Welded Joints between AA7075 and AA6061 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    İpekoğlu, Güven; Çam, Gürel

    2014-06-01

    In this study, dissimilar AA7075-O/6061-O and AA7075-T6/6061-T6 butt joints were produced by friction stir welding (FSW), and postweld heat treatment (PWHT) was applied to the joints obtained. The effects of initial temper condition and PWHT on the microstructure and mechanical properties of the dissimilar joints were thus investigated. It was demonstrated that sound dissimilar joints can be produced for both temper conditions. A hardness increase in the joint area ( i.e., strength overmatching) was obtained in the joints produced in the O-temper condition, whereas a hardness loss was observed in the joint area of the joints obtained in the T6 temper condition. It was also well demonstrated that PWHT could be used in order to improve the joint properties for both O and T6 joints provided that the joint is defect-free prior to subsequent heat treatment.

  15. Aim, Load, Fire: The Type VI Secretion System, a Bacterial Nanoweapon.

    PubMed

    Cianfanelli, Francesca R; Monlezun, Laura; Coulthurst, Sarah J

    2016-01-01

    Bacteria utilise specialised protein secretion systems to interact with host organisms, competitor bacteria, and the environment. The Type VI secretion system (T6SS) is a versatile weapon deployed by many bacterial species to target either host cells or rival bacteria. The widespread occurrence and significance of the T6SS is becoming increasingly appreciated, as is its intriguing mode of action. The T6SS delivers multiple, diverse effector proteins directly into target cells using a dynamic 'firing' mechanism related to the action of contractile bacteriophage tails. Here, we summarise the contribution of recent findings to our developing picture of how the T6SS assembles and fires, how it is loaded with different types of effectors, and how it can be aimed towards an incoming assault. PMID:26549582

  16. 12 CFR 165.4 - Capital measures and capital category definitions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... directive, or prompt corrective action directive issued by the OCC or OTS under section 8 of the FDI Act....C. 1464(t)(6)(A)(ii)), or section 38 of the FDI Act, or any regulation thereunder, to meet...

  17. Stress-corrosion-induced property changes in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Bankston, B. F.; Clotfelter, W. N.

    1968-01-01

    Measurements of electrical conductivity, ultrasonic surface wave attenuation, and internal friction loss were made on aluminum alloys 7079-T6, 2219-T31, and 2219-T81 as a function of the onset of stress corrosion.

  18. Evaluation of the roles played by Hcp and VgrG type 6 secretion system effectors in Aeromonas hydrophila SSU pathogenesis

    PubMed Central

    Sha, Jian; Rosenzweig, Jason A.; Kozlova, Elena V.; Wang, Shaofei; Erova, Tatiana E.; Kirtley, Michelle L.; van Lier, Christina J.

    2013-01-01

    Aeromonas hydrophila, a Gram-negative bacterium, is an emerging human pathogen equipped with both a type 3 and a type 6 secretion system (T6SS). In this study, we evaluated the roles played by paralogous T6SS effector proteins, hemolysin co-regulated proteins (Hcp-1 and -2) and valine glycine repeat G (VgrG-1, -2 and -3) protein family members in A. hydrophila SSU pathogenesis by generating various combinations of deletion mutants of the their genes. In addition to their predicted roles as structural components and effector proteins of the T6SS, our data clearly demonstrated that paralogues of Hcp and VgrG also influenced bacterial motility, protease production and biofilm formation. Surprisingly, there was limited to no observed functional redundancy among and/or between the aforementioned T6SS effector paralogues in multiple assays. Our data indicated that Hcp and VgrG paralogues located within the T6SS cluster were more involved in forming T6SS structures, while the primary roles of Hcp-1 and VgrG-1, located outside of the T6SS cluster, were as T6SS effectors. In terms of influence on bacterial physiology, Hcp-1, but not Hcp-2, influenced bacterial motility and protease production, and in its absence, increases in both of the aforementioned activities were observed. Likewise, VgrG-1 played a major role in regulating bacterial protease production, while VgrG-2 and VgrG-3 were critical in regulating bacterial motility and biofilm formation. In an intraperitoneal murine model of infection, all Hcp and VgrG paralogues were required for optimal bacterial virulence and dissemination to mouse peripheral organs. Importantly, the observed phenotypic alterations of the T6SS mutants could be fully complemented. Taking these results together, we have further established the roles played by the two known T6SS effectors of A. hydrophila by defining their contributions to T6SS function and virulence in both in vitro and in vivo models of infection. PMID:23519162

  19. Source/sink interactions underpin crop yield: the case for trehalose 6-phosphate/SnRK1 in improvement of wheat.

    PubMed

    Lawlor, David W; Paul, Matthew J

    2014-01-01

    Considerable interest has been evoked by the analysis of the regulatory pathway in carbohydrate metabolism and cell growth involving the non-reducing disaccharide trehalose (TRE). TRE is at small concentrations in mesophytes such as Arabidopsis thaliana and Triticum aestivum, excluding a role in osmoregulation once suggested for it. Studies of TRE metabolism, and genetic modification of it, have shown a very wide and more important role of the pathway in regulation of many processes in development, growth, and photosynthesis. It has now been established that rather than TRE, it is trehalose 6-phosphate (T6P) which has such profound effects. T6P is the intermediary in TRE synthesis formed from glucose-6-phosphate and UDP-glucose, derived from sucrose, by the action of trehalose phosphate synthase. The concentration of T6P is determined both by the rate of synthesis, which depends on the sucrose concentration, and also by the rate of breakdown by trehalose-6-phosphate phosphatase which produces TRE. Changing T6P concentrations by genetically modifying the enzymes of synthesis and breakdown has altered photosynthesis, sugar metabolism, growth, and development which affect responses to, and recovery from, environmental factors. Many of the effects of T6P on metabolism and growth occur via the interaction of T6P with the SnRK1 protein kinase system. T6P inhibits the activity of SnRK1, which de-represses genes encoding proteins involved in anabolism. Consequently, a large concentration of sucrose increases T6P and thereby inhibits SnRK1, so stimulating growth of cells and their metabolic activity. The T6P/SnRK1 mechanism offers an important new view of how the distribution of assimilates to organs, such as developing grains in cereal plants, is achieved. This review briefly summarizes the factors determining, and limiting, yield of wheat (particularly mass/grain which is highly conserved) and considers how T6P/SnRK1 might function to determine grain yield and might be

  20. 77 FR 59220 - Alaska Native Claims Selection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-26

    .... Survey No. 9993, Alaska. Containing 129.97 acres. Kateel River Meridian, Alaska T. 5 S., R. 24 W., Tract A. Containing 1,242.28 acres. T. 6 S., R. 24 W., Secs. 6, 21, 22, 28, and 33. Containing 3,164.08 acres. T. 6 S., R. 25 W., Tracts Q, R, and S; Tracts T, X, and Z. Containing approximately 1,683...

  1. Fatigue Performance of Fluidized Bed Heat Treated 319 Alloy Diesel Cylinder Heads

    NASA Astrophysics Data System (ADS)

    Chaudhury, Sujoy K.; Apelian, Diran; Meyer, Philippe; Massinon, Denis; Morichon, Julien

    2015-07-01

    Effects of various heat treatment tempers on fatigue performance of 319 alloy diesel cylinder heads were investigated. Castings were heat treated to T5, T6, and T7 tempers. Castings were solution heat treated and quenched using fluidized beds and aged using both conventional air convective furnace and fluidized bed for T6 and T7 tempers; while they were aged after casting for T5 temper using conventional furnace. Fatigue tests were performed at 373 K (100 °C) and stress ratio equal to -1. Results show that heat treatment has significant effect on the fatigue behavior of 319 alloy. The fatigue strength of T6 tempered 319 alloy is greater than T5 and T7 treatments. Weibull analysis shows that the Weibull modulus and characteristic fatigue life of castings treated (using conventional forced air circulation electrical resistance furnace) to T6 and T7 tempers are greater than T5 temper. This implies that castings treated to T6 and T7 tempers have greater reliability vis-à-vis T5 temper. Fractographic analyses reveal three distinct regions. These are: (I) crack initiation region from the surface, (II) crack propagation region, and (III) catastrophic or monotonic failure region. The relative size of the crack propagation region in T6 and T7 treated samples is greater than T5 treated samples. In general, the monotonic failure region shows typical dimple morphology, which implies significant plastic deformation prior to failure. Dimples on the fractured surface of T5 treated alloy are relatively more faceted than those treated to T6 and T7 tempers. This implies that the 319 alloy treated to T6 and T7 tempers underwent higher degree of plasticity prior to failure than that in the T5 condition.

  2. Genetically distinct pathways guide effector export through the type VI secretion system

    PubMed Central

    Whitney, John C.; Beck, Christina M.; Goo, Young Ah; Russell, Alistair B.; Harding, Brittany; De Leon, Justin A.; Cunningham, David A.; Tran, Bao Q.; Low, David A.; Goodlett, David R.; Hayes, Christopher S.; Mougous, Joseph D.

    2014-01-01

    Summary Bacterial secretion systems often employ molecular chaperones to recognize and facilitate export of their substrates. Recent work demonstrated that a secreted component of the type VI secretion system (T6SS), hemolysin co-regulated protein (Hcp), binds directly to effectors, enhancing their stability in the bacterial cytoplasm. Herein, we describe a quantitative cellular proteomics screen for T6S substrates that exploits this chaperone-like quality of Hcp. Application of this approach to the Hcp secretion island I-encoded T6SS (H1-T6SS) of Pseudomonas aeruginosa led to the identification of a novel effector protein, termed Tse4 (type VI secretion exported 4), subsequently shown to act as a potent intra-specific H1-T6SS-delivered antibacterial toxin. Interestingly, our screen failed to identify two predicted H1-T6SS effectors, Tse5 and Tse6, which differ from Hcp-stabilized substrates by the presence of toxin-associated PAAR-repeat motifs and genetic linkage to members of the valine-glycine repeat protein G (vgrG) genes. Genetic studies further distinguished these two groups of effectors: Hcp-stabilized effectors were found to display redundancy in interbacterial competition with respect to the requirement for the two H1-T6SS-exported VgrG proteins, whereas Tse5 and Tse6 delivery strictly required a cognate VgrG. Together, we propose that interaction with either VgrG or Hcp defines distinct pathways for T6S effector export. PMID:24589350

  3. Bacteroides fragilis type VI secretion systems use novel effector and immunity proteins to antagonize human gut Bacteroidales species.

    PubMed

    Chatzidaki-Livanis, Maria; Geva-Zatorsky, Naama; Comstock, Laurie E

    2016-03-29

    Type VI secretion systems (T6SSs) are multiprotein complexes best studied in Gram-negative pathogens where they have been shown to inhibit or kill prokaryotic or eukaryotic cells and are often important for virulence. We recently showed that T6SS loci are also widespread in symbiotic human gut bacteria of the order Bacteroidales, and that these T6SS loci segregate into three distinct genetic architectures (GA). GA1 and GA2 loci are present on conserved integrative conjugative elements (ICE) and are transferred and shared among diverse human gut Bacteroidales species. GA3 loci are not contained on conserved ICE and are confined toBacteroides fragilis Unlike GA1 and GA2 T6SS loci, most GA3 loci do not encode identifiable effector and immunity proteins. Here, we studied GA3 T6SSs and show that they antagonize most human gut Bacteroidales strains analyzed, except forB. fragilisstrains with the same T6SS locus. A combination of mutation analyses,trans-protection analyses, and in vitro competition assays, allowed us to identify novel effector and immunity proteins of GA3 loci. These proteins are not orthologous to known proteins, do not contain identified motifs, and most have numerous predicted transmembrane domains. Because the genes encoding effector and immunity proteins are contained in two variable regions of GA3 loci, GA3 T6SSs of the speciesB. fragilisare likely the source of numerous novel effector and immunity proteins. Importantly, we show that the GA3 T6SS of strain 638R is functional in the mammalian gut and provides a competitive advantage to this organism. PMID:26951680

  4. Expression, secretion and bactericidal activity of type VI secretion system in Vibrio anguillarum.

    PubMed

    Tang, Lei; Yue, Shu; Li, Gui-Yang; Li, Jie; Wang, Xiao-Ran; Li, Shu-Fang; Mo, Zhao-Lan

    2016-10-01

    The type VI secretion system (T6SS) was recently shown to modulate quorum sensing and the stress response in Vibrio anguillarum serotype O1 strain NB10. It is not known whether there is a functionally active T6SS in other serotypes of V. anguillarum. Here, homologues to T6SS cluster VtsEFGH and hemolysin-coregulated protein (Hcp)-encoding genes were found to be prevalent and conserved in clinical isolates of V. anguillarum from fish, including four O1 and five non-O1 serotype strains. Unexpectedly, only the non-O1 serotype strains expressed VtsEFGH and Hcp under laboratory and marine-like conditions, in contrast to the serotype O1 strains. This suggested that the V. anguillarum non-O1 serotype strains tested have constitutive expression of T6SS. Examination of a representative non-O1 strain, MHK3, showed that Hcp production was growth phase dependent and that maximum Hcp production was observed in the exponential growth phase. Moreover, Hcp production by MHK3 was most active under warm marine-like conditions. Further examination revealed a correlation of the constitutive expression of T6SS with bactericidal activity against Escherichia coli and Edwardsiella tarda. The work presented here suggests that the constitutive expression of T6SS provides V. anguillarum with advantage in microbial competition in marine environments. PMID:27172981

  5. Visualization of the Serratia Type VI Secretion System Reveals Unprovoked Attacks and Dynamic Assembly

    PubMed Central

    Gerc, Amy J.; Diepold, Andreas; Trunk, Katharina; Porter, Michael; Rickman, Colin; Armitage, Judith P.; Stanley-Wall, Nicola R.; Coulthurst, Sarah J.

    2015-01-01

    Summary The Type VI secretion system (T6SS) is a bacterial nanomachine that fires toxic proteins into target cells. Deployment of the T6SS represents an efficient and widespread means by which bacteria attack competitors or interact with host organisms and may be triggered by contact from an attacking neighbor cell as a defensive strategy. Here, we use the opportunist pathogen Serratia marcescens and functional fluorescent fusions of key components of the T6SS to observe different subassemblies of the machinery simultaneously and on multiple timescales in vivo. We report that the localization and dynamic behavior of each of the components examined is distinct, revealing a multi-stage and dynamic assembly process for the T6SS machinery. We also show that the T6SS can assemble and fire without needing a cell contact trigger, defining an aggressive strategy that broadens target range and suggesting that activation of the T6SS is tailored to survival in specific niches. PMID:26387948

  6. Visualization of the Serratia Type VI Secretion System Reveals Unprovoked Attacks and Dynamic Assembly.

    PubMed

    Gerc, Amy J; Diepold, Andreas; Trunk, Katharina; Porter, Michael; Rickman, Colin; Armitage, Judith P; Stanley-Wall, Nicola R; Coulthurst, Sarah J

    2015-09-29

    The Type VI secretion system (T6SS) is a bacterial nanomachine that fires toxic proteins into target cells. Deployment of the T6SS represents an efficient and widespread means by which bacteria attack competitors or interact with host organisms and may be triggered by contact from an attacking neighbor cell as a defensive strategy. Here, we use the opportunist pathogen Serratia marcescens and functional fluorescent fusions of key components of the T6SS to observe different subassemblies of the machinery simultaneously and on multiple timescales in vivo. We report that the localization and dynamic behavior of each of the components examined is distinct, revealing a multi-stage and dynamic assembly process for the T6SS machinery. We also show that the T6SS can assemble and fire without needing a cell contact trigger, defining an aggressive strategy that broadens target range and suggesting that activation of the T6SS is tailored to survival in specific niches. PMID:26387948

  7. Type VI secretion system: secretion by a contractile nanomachine

    PubMed Central

    Basler, Marek

    2015-01-01

    The type VI secretion systems (T6SS) are present in about a quarter of all Gram-negative bacteria. Several key components of T6SS are evolutionarily related to components of contractile nanomachines such as phages and R-type pyocins. The T6SS assembly is initiated by formation of a membrane complex that binds a phage-like baseplate with a sharp spike, and this is followed by polymerization of a long rigid inner tube and an outer contractile sheath. Effectors are preloaded onto the spike or into the tube during the assembly by various mechanisms. Contraction of the sheath releases an unprecedented amount of energy, which is used to thrust the spike and tube with the associated effectors out of the effector cell and across membranes of both bacterial and eukaryotic target cells. Subunits of the contracted sheath are recycled by T6SS-specific unfoldase to allow for a new round of assembly. Live-cell imaging has shown that the assembly is highly dynamic and its subcellular localization is in certain bacteria regulated with a remarkable precision. Through the action of effectors, T6SS has mainly been shown to contribute to pathogenicity and competition between bacteria. This review summarizes the knowledge that has contributed to our current understanding of T6SS mode of action. PMID:26370934

  8. Chelation of Membrane-Bound Cations by Extracellular DNA Activates the Type VI Secretion System in Pseudomonas aeruginosa.

    PubMed

    Wilton, Mike; Wong, Megan J Q; Tang, Le; Liang, Xiaoye; Moore, Richard; Parkins, Michael D; Lewenza, Shawn; Dong, Tao G

    2016-08-01

    Pseudomonas aeruginosa employs its type VI secretion system (T6SS) as a highly effective and tightly regulated weapon to deliver toxic molecules to target cells. T6SS-secreted proteins of P. aeruginosa can be detected in the sputum of cystic fibrosis (CF) patients, who typically present a chronic and polymicrobial lung infection. However, the mechanism of T6SS activation in the CF lung is not fully understood. Here we demonstrate that extracellular DNA (eDNA), abundant within the CF airways, stimulates the dynamics of the H1-T6SS cluster apparatus in Pseudomonas aeruginosa PAO1. Addition of Mg(2+) or DNase with eDNA abolished such activation, while treatment with EDTA mimicked the eDNA effect, suggesting that the eDNA-mediated effect is due to chelation of outer membrane-bound cations. DNA-activated H1-T6SS enables P. aeruginosa to nonselectively attack neighboring species regardless of whether or not it was provoked. Because of the importance of the T6SS in interspecies interactions and the prevalence of eDNA in the environments that P. aeruginosa inhabits, our report reveals an important adaptation strategy that likely contributes to the competitive fitness of P. aeruginosa in polymicrobial communities. PMID:27271742

  9. Anticytoproliferative effect of Vitamin C on rat hepatic stellate cell

    PubMed Central

    Su, Min; Chao, Guo; Liang, Minqing; Song, Jianhua; Wu, Ka

    2016-01-01

    This study was conducted to investigate the potential therapeutical benefit of Vitamin (VC), a potent antioxidant, on suppressing proliferation of immortalized rat liver stellate cell line (HSC-T6) in vitro, and to discuss the underlying mechanism. HSC-T6 was co-treated with different concentrations of VC (50, 100, 200 μmol/L) on designed time points. Then, cell viability was assessed by using MTT analysis, and the changes of cytomorphology was observed with apoptosis-specific TUNEL and immunohistochemical stains, as well as the intracellular target genes was determined by using RT-PCR, respectively. As the outcomes, VC-treated HSC-T6 showed significantly inhibited cell growth in a dose-dependent manner when compared to the vehicle control. Cytologically, VC increased TUNEL-labeled positive cells in cultured HSC-T6, which the cell count was greater than vehicle control. Meanwhile, VC-treated HSC-T6 showed elevated immunoreactive for TGF-β1-labeled cells. Moreover, VC contributed to down-regulated expressions of intracellular c-myc, cyclin D1, mTOR mRNAs in HSC-T6. Collectively, these preliminary findings have demonstrated that VC-mediated anti-proliferative effect on HSCs is involved in molecular mechanisms of promoting apoptosis and blocking endogenous collagenation. PMID:27398165

  10. Shifts in microbial community composition and function in the acidification of a lead/zinc mine tailings.

    PubMed

    Chen, Lin-Xing; Li, Jin-Tian; Chen, Ya-Ting; Huang, Li-Nan; Hua, Zheng-Shuang; Hu, Min; Shu, Wen-Sheng

    2013-09-01

    In an attempt to link the microbial community composition and function in mine tailings to the generation of acid mine drainage, we simultaneously explored the geochemistry and microbiology of six tailings collected from a lead/zinc mine, i.e. primary tailings (T1), slightly acidic tailings (T2), extremely acidic tailings (T3, T4 and T5) and orange-coloured oxidized tailings (T6). Geochemical results showed that the six tailings (from T1 to T6) likely represented sequential stages of the acidification process of the mine tailings. 16S rRNA pyrosequencing revealed a contrasting microbial composition between the six tailings: Proteobacteria-related sequences dominated T1-T3 with relative abundance ranging from 56 to 93%, whereas Ferroplasma-related sequences dominated T4-T6 with relative abundance ranging from 28 to 58%. Furthermore, metagenomic analysis of the microbial communities of T2 and T6 indicated that the genes encoding key enzymes for microbial carbon fixation, nitrogen fixation and sulfur oxidation in T2 were largely from Thiobacillus and Acidithiobacillus, Methylococcus capsulatus, and Thiobacillus denitrificans respectively; while those in T6 were mostly identified in Acidithiobacillus and Leptospirillum, Acidithiobacillus and Leptospirillum, and Acidithiobacillus respectively. The microbial communities in T2 and T6 harboured more genes suggesting diverse metabolic capacities for sulfur oxidation/heavy metal detoxification and tolerating low pH respectively. PMID:23574280

  11. Purification, crystallization and preliminary X-ray crystallographic analysis of TssL from Vibrio cholerae

    PubMed Central

    Jeong, Jae-Hee; Chang, Jeong Ho; Kim, Yeon-Gil

    2014-01-01

    The type VI secretion system (T6SS) is a macromolecular complex that is conserved in Gram-negative bacteria. The T6SS secretes effector proteins into recipient cells in a contact-dependent manner in order to accomplish cooperative and competitive interactions with the cells. Although the composition and mechanism of the T6SS have been intensively investigated across many Gram-negative bacteria, to date structural information on T6SS components from the important pathogen Vibrio cholerae has been rare. Here, the cloning, purification, crystallization and preliminary X-ray crystallographic analysis of the cytoplasmic domain of TssL, an inner membrane protein of the T6SS, from V. cholerae are reported. Diffraction data were collected to 1.5 Å resolution using synchrotron radiation. The crystal belonged to the hexagonal space group P61, with unit-cell parameters a = 78.4, b = 78.4, c = 49.5 Å. The successful structural characterization of TssL from V. cholerae will contribute to understanding the role of the membrane-associated subunits of the T6SS in more detail. PMID:25195905

  12. Gene Expression of Type VI Secretion System Associated with Environmental Survival in Acidovorax avenae subsp. avenae by Principle Component Analysis

    PubMed Central

    Cui, Zhouqi; Jin, Guoqiang; Li, Bin; Kakar, Kaleem Ullah; Ojaghian, Mohammad Reza; Wang, Yangli; Xie, Guanlin; Sun, Guochang

    2015-01-01

    Valine glycine repeat G (VgrG) proteins are regarded as one of two effectors of Type VI secretion system (T6SS) which is a complex multi-component secretion system. In this study, potential biological roles of T6SS structural and VgrG genes in a rice bacterial pathogen, Acidovorax avenae subsp. avenae (Aaa) RS-1, were evaluated under seven stress conditions using principle component analysis of gene expression. The results showed that growth of the pathogen was reduced by H2O2 and paraquat-induced oxidative stress, high salt, low temperature, and vgrG mutation, compared to the control. However, pathogen growth was unaffected by co-culture with a rice rhizobacterium Burkholderia seminalis R456. In addition, expression of 14 T6SS structural and eight vgrG genes was significantly changed under seven conditions. Among different stress conditions, high salt, and low temperature showed a higher effect on the expression of T6SS gene compared with host infection and other environmental conditions. As a first report, this study revealed an association of T6SS gene expression of the pathogen with the host infection, gene mutation, and some common environmental stresses. The results of this research can increase understanding of the biological function of T6SS in this economically-important pathogen of rice. PMID:26378528

  13. Hybridization is limited between two lineages of freeze-resistant Trichinella during coinfection in a mouse model.

    PubMed

    Hecht, Luke B B; Thompson, Peter C; Lavin, Elizabeth S; Zarlenga, Dante S; Rosenthal, Benjamin M

    2016-03-01

    Hybridization between two closely related but distinct genetic lineages may lead to homogenization of the two lineages with potentially novel phenotypes, or selective pressure to avoid hybridization if the two lineages are truly distinct. Trichinella nativa and Trichinella T6 are zoonotic nematode parasites which can be distinguished genetically despite occasional hybridization. Here, using an experimental murine model, we attempt to determine whether there are barriers to hybridization when sizeable numbers of each lineage are allowed to coinfect a host. Two mice were independently infected with equal numbers of T. nativa and T6. The offspring of these coinfections were genotyped at two microsatellite loci and one mitochondrial locus capable of distinguishing T. nativa from T6 genotypes. Among larvae in the F1 generation, offspring of every possible mating were encountered. Most larvae (63.6%) derived from T. nativa×T. nativa matings, while 21.1% of offspring were the product of T6×T6 matings, and only 15.3% were hybrid offspring of T. nativa×T6 crosses, differing markedly from null expectations. In this experimental model, T. nativa and Trichinella T6 were able to mate, but ratios of offspring indicated pre- or post-zygotic barriers to hybridization that may include assortative mating, genetic incompatibilities, and/or differences in the fitness of offspring. These barriers would limit gene flow between these two lineages in a natural setting, serving as a barrier to their homogenization and promoting their persistence as distinct and separate entities. PMID:26721624

  14. Higher brain centers for social tasks in worker ants, Camponotus japonicus.

    PubMed

    Nishikawa, Michiko; Watanabe, Hidehiro; Yokohari, Fumio

    2012-05-01

    Ants, eusocial insects, have highly elaborate chemical communication systems using a wide variety of pheromones. In the carpenter ant, Camponotus japonicus, workers and queens have the female-specific basiconic sensilla on antennae. The antennal lobe, the primary processing center, in female carpenter ants contains about 480 glomeruli, which are divided into seven groups (T1–T7 glomeruli) based on sensory afferent tracts. The axons of sensory neurons in basiconic sensilla are thought to project to female-specific T6 glomeruli. Therefore, these sensilla and glomeruli are thought to relate to female-specific social tasks in the ants. By using dye filling into local neurons (LNs) and projection neurons (PNs) in the antennal lobe, we neuroanatomically revealed the existence of an isolated processing system for signals probably relating to social tasks in the worker ant. In the antennal lobe, two categories of glomeruli, T6 glomeruli and non-T6 glomeruli, are clearly segregated by LNs. Furthermore, axon terminals of uniglomerular PNs from the respective categories of glomeruli (T6 uni-PNs and non-T6 uni-PNs) are also segregated in the secondary olfactory centers, the calyces of the mushroom body and the lateral horn: T6 uni-PNs terminate in the outer layers of the basal ring and lip of mushroom body calyces and in the posterior region of the lateral horn, whereas non-T6 uni-PNs terminate in the middle and inner layers of the basal ring and lip and in the anterior region of the lateral horn. These findings suggest that information probably relating to social tasks might be isolated from other olfactory information and processed in a separate subsystem. PMID:22102363

  15. The icmF3 locus is involved in multiple adaptation- and virulence-related characteristics in Pseudomonas aeruginosa PAO1.

    PubMed

    Lin, Jinshui; Cheng, Juanli; Chen, Keqi; Guo, Chenghao; Zhang, Weipeng; Yang, Xu; Ding, Wei; Ma, Li; Wang, Yao; Shen, Xihui

    2015-01-01

    The type VI secretion system (T6SS) is widely distributed in Gram-negative bacteria. Three separate T6SSs called H1-, H2-, and H3-T6SS have been discovered in Pseudomonas aeruginosa PAO1. Recent studies suggest that, in contrast to the H1-T6SS that targets prokaryotic cells, H2- and H3-T6SS are involved in interactions with both prokaryotic and eukaryotic cells. However, the detailed functions of T6SS components are still uncharacterized. The intracellular multiplication factor (IcmF) protein is conserved in type VI secretion systems (T6SS) of all different bacterial pathogens. Bioinformatic analysis revealed that IcmF3 in P. aeruginosa PAO1 is different from other IcmF homologs and may represent a new branch of these proteins with distinct functions. Herein, we have investigated the function of IcmF3 in this strain. We have shown that deletion of the icmF3 gene in P. aeruginosa PAO1 is associated with pleiotropic phenotypes. The icmF3 mutant has variant colony morphology and an hypergrowth phenotype in iron-limiting medium. Surprisingly, this mutant is also defective for the production of pyoverdine, as well as defects in swimming motility and virulence in a C. elegans worm model. The icmF3 mutant exhibits higher conjugation frequency than the wild type and increased biofilm formation on abiotic surfaces. Additionally, expression of two phenazine biosynthetic loci is increased in the icmF3 mutant, leading to the overproduction of pyocyanin. Finally, the mutant exhibits decreased susceptibility to aminoglycosides such as tobramycin and gentamicin. And the detected phenotypes can be restored completely or partially by trans complementation of wild type icmF3 gene. The pleiotropic effects observed upon icmF3 deletion demonstrate that icmF3 plays critical roles in both pathogenesis and environmental adaptation in P. aeruginosa PAO1. PMID:26484316

  16. Burkholderia mallei and Burkholderia pseudomallei Cluster 1 Type VI Secretion System Gene Expression Is Negatively Regulated by Iron and Zinc

    PubMed Central

    Burtnick, Mary N.; Brett, Paul J.

    2013-01-01

    Burkholderia mallei is a facultative intracellular pathogen that causes glanders in humans and animals. Previous studies have demonstrated that the cluster 1 type VI secretion system (T6SS-1) expressed by this organism is essential for virulence in hamsters and is positively regulated by the VirAG two-component system. Recently, we have shown that T6SS-1 gene expression is up-regulated following internalization of this pathogen into phagocytic cells and that this system promotes multinucleated giant cell formation in infected tissue culture monolayers. In the present study, we further investigated the complex regulation of this important virulence factor. To assess T6SS-1 expression, B. mallei strains were cultured in various media conditions and Hcp1 production was analyzed by Western immunoblotting. Transcript levels of several VirAG-regulated genes (bimA, tssA, hcp1 and tssM) were also determined using quantitative real time PCR. Consistent with previous observations, T6SS-1 was not expressed during growth of B. mallei in rich media. Curiously, growth of the organism in minimal media (M9G) or minimal media plus casamino acids (M9CG) facilitated robust expression of T6SS-1 genes whereas growth in minimal media plus tryptone (M9TG) did not. Investigation of this phenomenon confirmed a regulatory role for VirAG in this process. Additionally, T6SS-1 gene expression was significantly down-regulated by the addition of iron and zinc to M9CG. Other genes under the control of VirAG did not appear to be as tightly regulated by these divalent metals. Similar results were observed for B. pseudomallei, but not for B. thailandensis. Collectively, our findings indicate that in addition to being positively regulated by VirAG, B. mallei and B. pseudomallei T6SS-1 gene expression is negatively regulated by iron and zinc. PMID:24146925

  17. The icmF3 locus is involved in multiple adaptation- and virulence-related characteristics in Pseudomonas aeruginosa PAO1

    PubMed Central

    Lin, Jinshui; Cheng, Juanli; Chen, Keqi; Guo, Chenghao; Zhang, Weipeng; Yang, Xu; Ding, Wei; Ma, Li; Wang, Yao; Shen, Xihui

    2015-01-01

    The type VI secretion system (T6SS) is widely distributed in Gram-negative bacteria. Three separate T6SSs called H1-, H2-, and H3-T6SS have been discovered in Pseudomonas aeruginosa PAO1. Recent studies suggest that, in contrast to the H1-T6SS that targets prokaryotic cells, H2- and H3-T6SS are involved in interactions with both prokaryotic and eukaryotic cells. However, the detailed functions of T6SS components are still uncharacterized. The intracellular multiplication factor (IcmF) protein is conserved in type VI secretion systems (T6SS) of all different bacterial pathogens. Bioinformatic analysis revealed that IcmF3 in P. aeruginosa PAO1 is different from other IcmF homologs and may represent a new branch of these proteins with distinct functions. Herein, we have investigated the function of IcmF3 in this strain. We have shown that deletion of the icmF3 gene in P. aeruginosa PAO1 is associated with pleiotropic phenotypes. The icmF3 mutant has variant colony morphology and an hypergrowth phenotype in iron-limiting medium. Surprisingly, this mutant is also defective for the production of pyoverdine, as well as defects in swimming motility and virulence in a C. elegans worm model. The icmF3 mutant exhibits higher conjugation frequency than the wild type and increased biofilm formation on abiotic surfaces. Additionally, expression of two phenazine biosynthetic loci is increased in the icmF3 mutant, leading to the overproduction of pyocyanin. Finally, the mutant exhibits decreased susceptibility to aminoglycosides such as tobramycin and gentamicin. And the detected phenotypes can be restored completely or partially by trans complementation of wild type icmF3 gene. The pleiotropic effects observed upon icmF3 deletion demonstrate that icmF3 plays critical roles in both pathogenesis and environmental adaptation in P. aeruginosa PAO1. PMID:26484316

  18. VgrG and PAAR Proteins Define Distinct Versions of a Functional Type VI Secretion System.

    PubMed

    Cianfanelli, Francesca R; Alcoforado Diniz, Juliana; Guo, Manman; De Cesare, Virginia; Trost, Matthias; Coulthurst, Sarah J

    2016-06-01

    The Type VI secretion system (T6SS) is widespread among bacterial pathogens and acts as an effective weapon against competitor bacteria and eukaryotic hosts by delivering toxic effector proteins directly into target cells. The T6SS utilises a bacteriophage-like contractile machinery to expel a puncturing device based on a tube of Hcp topped with a VgrG spike, which can be extended by a final tip from a PAAR domain-containing protein. Effector proteins are believed to be delivered by specifically associating with particular Hcp, VgrG or PAAR proteins, either covalently ('specialised') or non-covalently ('cargo' effectors). Here we used the T6SS of the opportunistic pathogen Serratia marcescens, together with integratecd genetic, proteomic and biochemical approaches, to elucidate the role of specific VgrG and PAAR homologues in T6SS function and effector specificity, revealing new aspects and unexpected subtleties in effector delivery by the T6SS. We identified effectors, both cargo and specialised, absolutely dependent on a particular VgrG for delivery to target cells, and discovered that other cargo effectors can show a preference for a particular VgrG. The presence of at least one PAAR protein was found to be essential for T6SS function, consistent with designation as a 'core' T6SS component. We showed that specific VgrG-PAAR combinations are required to assemble a functional T6SS and that the three distinct VgrG-PAAR assemblies in S. marcescens exhibit distinct effector specificity and efficiency. Unexpectedly, we discovered that two different PAAR-containing Rhs proteins can functionally pair with the same VgrG protein. Showing that accessory EagR proteins are involved in these interactions, native VgrG-Rhs-EagR complexes were isolated and specific interactions between EagR and cognate Rhs proteins identified. This study defines an essential yet flexible role for PAAR proteins in the T6SS and highlights the existence of distinct versions of the machinery with

  19. A Type VI Secretion System Is Involved in Pseudomonas fluorescens Bacterial Competition

    PubMed Central

    Decoin, Victorien; Barbey, Corinne; Bergeau, Dorian; Latour, Xavier; Feuilloley, Marc G. J.; Orange, Nicole; Merieau, Annabelle

    2014-01-01

    Protein secretion systems are crucial mediators of bacterial interactions with other organisms. Among them, the type VI secretion system (T6SS) is widespread in Gram-negative bacteria and appears to inject toxins into competitor bacteria and/or eukaryotic cells. Major human pathogens, such as Vibrio cholerae, Burkholderia and Pseudomonas aeruginosa, express T6SSs. Bacteria prevent self-intoxication by their own T6SS toxins by producing immunity proteins, which interact with the cognate toxins. We describe here an environmental P. fluorescens strain, MFE01, displaying an uncommon oversecretion of Hcp (hemolysin-coregulated protein) and VgrG (valine-glycine repeat protein G) into the culture medium. These proteins are characteristic components of a functional T6SS. The aim of this study was to attribute a role to this energy-consuming overexpression of the T6SS. The genome of MFE01 contains at least two hcp genes (hcp1 and hcp2), suggesting that there may be two putative T6SS clusters. Phenotypic studies have shown that MFE01 is avirulent against various eukaryotic cell models (amebas, plant or animal cell models), but has antibacterial activity against a wide range of competitor bacteria, including rhizobacteria and clinical bacteria. Depending on the prey cell, mutagenesis of the hcp2 gene in MFE01 abolishes or reduces this antibacterial killing activity. Moreover, the introduction of T6SS immunity proteins from S. marcescens, which is not killed by MFE01, protects E. coli against MFE01 killing. These findings suggest that the protein encoded by hcp2 is involved in the killing activity of MFE01 mediated by effectors of the T6SS targeting the peptidoglycan of Gram-negative bacteria. Our results indicate that MFE01 can protect potato tubers against Pectobacterium atrosepticum, which causes tuber soft rot. Pseudomonas fluorescens is often described as a major PGPR (plant growth-promoting rhizobacterium), and our results suggest that there may be a connection between

  20. A type VI secretion system is involved in Pseudomonas fluorescens bacterial competition.

    PubMed

    Decoin, Victorien; Barbey, Corinne; Bergeau, Dorian; Latour, Xavier; Feuilloley, Marc G J; Orange, Nicole; Merieau, Annabelle

    2014-01-01

    Protein secretion systems are crucial mediators of bacterial interactions with other organisms. Among them, the type VI secretion system (T6SS) is widespread in Gram-negative bacteria and appears to inject toxins into competitor bacteria and/or eukaryotic cells. Major human pathogens, such as Vibrio cholerae, Burkholderia and Pseudomonas aeruginosa, express T6SSs. Bacteria prevent self-intoxication by their own T6SS toxins by producing immunity proteins, which interact with the cognate toxins. We describe here an environmental P. fluorescens strain, MFE01, displaying an uncommon oversecretion of Hcp (hemolysin-coregulated protein) and VgrG (valine-glycine repeat protein G) into the culture medium. These proteins are characteristic components of a functional T6SS. The aim of this study was to attribute a role to this energy-consuming overexpression of the T6SS. The genome of MFE01 contains at least two hcp genes (hcp1 and hcp2), suggesting that there may be two putative T6SS clusters. Phenotypic studies have shown that MFE01 is avirulent against various eukaryotic cell models (amebas, plant or animal cell models), but has antibacterial activity against a wide range of competitor bacteria, including rhizobacteria and clinical bacteria. Depending on the prey cell, mutagenesis of the hcp2 gene in MFE01 abolishes or reduces this antibacterial killing activity. Moreover, the introduction of T6SS immunity proteins from S. marcescens, which is not killed by MFE01, protects E. coli against MFE01 killing. These findings suggest that the protein encoded by hcp2 is involved in the killing activity of MFE01 mediated by effectors of the T6SS targeting the peptidoglycan of Gram-negative bacteria. Our results indicate that MFE01 can protect potato tubers against Pectobacterium atrosepticum, which causes tuber soft rot. Pseudomonas fluorescens is often described as a major PGPR (plant growth-promoting rhizobacterium), and our results suggest that there may be a connection between

  1. VgrG and PAAR Proteins Define Distinct Versions of a Functional Type VI Secretion System

    PubMed Central

    Cianfanelli, Francesca R.; Alcoforado Diniz, Juliana; Guo, Manman; De Cesare, Virginia; Trost, Matthias; Coulthurst, Sarah J.

    2016-01-01

    The Type VI secretion system (T6SS) is widespread among bacterial pathogens and acts as an effective weapon against competitor bacteria and eukaryotic hosts by delivering toxic effector proteins directly into target cells. The T6SS utilises a bacteriophage-like contractile machinery to expel a puncturing device based on a tube of Hcp topped with a VgrG spike, which can be extended by a final tip from a PAAR domain-containing protein. Effector proteins are believed to be delivered by specifically associating with particular Hcp, VgrG or PAAR proteins, either covalently (‘specialised’) or non-covalently (‘cargo’ effectors). Here we used the T6SS of the opportunistic pathogen Serratia marcescens, together with integratecd genetic, proteomic and biochemical approaches, to elucidate the role of specific VgrG and PAAR homologues in T6SS function and effector specificity, revealing new aspects and unexpected subtleties in effector delivery by the T6SS. We identified effectors, both cargo and specialised, absolutely dependent on a particular VgrG for delivery to target cells, and discovered that other cargo effectors can show a preference for a particular VgrG. The presence of at least one PAAR protein was found to be essential for T6SS function, consistent with designation as a ‘core’ T6SS component. We showed that specific VgrG-PAAR combinations are required to assemble a functional T6SS and that the three distinct VgrG-PAAR assemblies in S. marcescens exhibit distinct effector specificity and efficiency. Unexpectedly, we discovered that two different PAAR-containing Rhs proteins can functionally pair with the same VgrG protein. Showing that accessory EagR proteins are involved in these interactions, native VgrG-Rhs-EagR complexes were isolated and specific interactions between EagR and cognate Rhs proteins identified. This study defines an essential yet flexible role for PAAR proteins in the T6SS and highlights the existence of distinct versions of the

  2. Fatigue Properties of Cast Magnesium Wheels

    NASA Astrophysics Data System (ADS)

    Li, Zhenming; Luo, Alan A.; Wang, Qigui; Peng, Liming; Zhang, Peng

    2016-05-01

    This paper investigates the fatigue properties and deformation behavior of a newly developed Mg-2.96Nd-0.21Zn-0.39Zr magnesium alloy wheel in both as-cast and T6 conditions. Compared with the as-cast alloy, the T6-treated alloy shows a significant increase in fatigue strength and cyclic stress amplitude. This is believed to be attributed to the change of defect type from porosity to oxides and the increased matrix strength in the T6 (peak-aged) condition. For the as-cast alloy wheel, fatigue failure mainly originated from the cast defects including porosity, oxide film, and inclusion at or near the sample surface. In the T6-treated alloy, however, oxides and inclusions or slip bands initiate the fatigue cracks. Solution treatment appears to reduce or eliminate the shrinkage porosity because of grain growth and dissolution of as-cast eutectic phases in the grain boundaries. The cyclic stress amplitude of the as-cast alloy increases with increasing the number of cycles, while the T6-treated alloy shows cyclic softening after the stress reaches a maximum value. The Coffin-Manson law and Basquin equation can be used to evaluate the life of low cycle fatigue. The developed long crack model and multi-scale fatigue (MSF) models can be used to predict high-cycle fatigue life of the Mg-2.96Nd-0.21Zn-0.39Zr alloys with or without casting defects.

  3. Structural Insights into mitochondrial antiviral signaling protein (MAVS)-tumor necrosis factor receptor-associated factor 6 (TRAF6) signaling.

    PubMed

    Shi, Zhubing; Zhang, Zhen; Zhang, Zhenzhen; Wang, Yanyan; Li, Chuanchuan; Wang, Xin; He, Feng; Sun, Lina; Jiao, Shi; Shi, Weiyang; Zhou, Zhaocai

    2015-10-30

    In response to viral infection, cytosolic retinoic acid-inducible gene I-like receptors sense viral RNA and promote oligomerization of mitochondrial antiviral signaling protein (MAVS), which then recruits tumor necrosis factor receptor-associated factor (TRAF) family proteins, including TRAF6, to activate an antiviral response. Currently, the interaction between MAVS and TRAF6 is only partially understood, and atomic details are lacking. Here, we demonstrated that MAVS directly interacts with TRAF6 through its potential TRAF6-binding motif 2 (T6BM2; amino acids 455-460). Further, we solved the crystal structure of MAVS T6BM2 in complex with the TRAF6 TRAF_C domain at 2.95 Å resolution. T6BM2 of MAVS binds to the canonical adaptor-binding groove of the TRAF_C domain. Structure-directed mutational analyses in vitro and in cells revealed that MAVS binding to TRAF6 via T6BM2 instead of T6BM1 is essential but not sufficient for an optimal antiviral response. Particularly, a MAVS mutant Y460E retained its TRAF6-binding ability as predicted but showed significantly impaired signaling activity, highlighting the functional importance of this tyrosine. Moreover, these observations were further confirmed in MAVS(-/-) mouse embryonic fibroblast cells. Collectively, our work provides a structural basis for understanding the MAVS-TRAF6 antiviral response. PMID:26385923

  4. Functional diversity and mutational analysis of Agrobacterium 6B oncoproteins.

    PubMed

    Helfer, A; Pien, S; Otten, L

    2002-07-01

    Many Agrobacterium T-DNA genes belong to a diverse family of T-DNA genes, the rolB family. These genes cause various growth abnormalities but their modes of action remain largely unknown. So far, none of the RolB-like proteins has been subjected to mutational analysis. The RolB-like oncoprotein 6B, which induces tumours on species such as Nicotiana glauca and Kalanchoe tubiflora, was chosen to investigate the role of the most conserved amino acid residues within the RolB family. We first determined which of the natural 6B variants had the strongest oncogenic activity; to this end, six 6b coding sequences (A- 6b, AB- 6b, C- 6b, CG- 6b, S- 6b and T- 6b) were placed under the control of the strong constitutive 2x35S promoter and compared for tumour induction on N. glauca, N. tabacum and K. daigremontiana. Oncogenicity increased in the order C- 6b/CG- 6b, A- 6b/AB- 6b, and S- 6b/T- 6b. The most conserved amino acid residues in the strongly oncogenic T-6B protein were mutated and shown to be required for oncogenicity and accumulation of the T-6B protein in planta but not in bacteria. Hybrids between T-6B and the weakly oncogenic A-6B protein revealed an additional oncogenic determinant required for the formation of large tumours. PMID:12172796

  5. TssA forms a gp6-like ring attached to the type VI secretion sheath.

    PubMed

    Planamente, Sara; Salih, Osman; Manoli, Eleni; Albesa-Jové, David; Freemont, Paul S; Filloux, Alain

    2016-08-01

    The type VI secretion system (T6SS) is a supra-molecular bacterial complex that resembles phage tails. It is a killing machine which fires toxins into target cells upon contraction of its TssBC sheath. Here, we show that TssA1 is a T6SS component forming dodecameric ring structures whose dimensions match those of the TssBC sheath and which can accommodate the inner Hcp tube. The TssA1 ring complex binds the T6SS sheath and impacts its behaviour in vivo In the phage, the first disc of the gp18 sheath sits on a baseplate wherein gp6 is a dodecameric ring. We found remarkable sequence and structural similarities between TssA1 and gp6 C-termini, and propose that TssA1 could be a baseplate component of the T6SS Furthermore, we identified similarities between TssK1 and gp8, the former interacting with TssA1 while the latter is found in the outer radius of the gp6 ring. These observations, combined with similarities between TssF and gp6N-terminus or TssG and gp53, lead us to propose a comparative model between the phage baseplate and the T6SS. PMID:27288401

  6. The Type VI Secretion System in Escherichia coli and Related Species.

    PubMed

    Journet, Laure; Cascales, Eric

    2016-05-01

    The type VI secretion system (T6SS) is a multiprotein complex widespread in Proteobacteria and dedicated to the delivery of toxins into both prokaryotic and eukaryotic cells. It thus participates in interbacterial competition as well as pathogenesis. The T6SS is a contractile weapon, related to the injection apparatus of contractile tailed bacteriophages. Basically, it assembles an inner tube wrapped by a sheath-like structure and anchored to the cell envelope via a membrane complex. The energy released by the contraction of the sheath propels the inner tube through the membrane channel and toward the target cell. Although the assembly and the mechanism of action are conserved across species, the repertoire of secreted toxins and the diversity of the regulatory mechanisms and of target cells make the T6SS a highly versatile secretion system. The T6SS is particularly represented in Escherichia coli pathotypes and Salmonella serotypes. In this review we summarize the current knowledge regarding the prevalence, the assembly, the regulation, and the roles of the T6SS in E. coli, Salmonella, and related species. PMID:27223818

  7. Quorum sensing control of Type VI secretion factors restricts the proliferation of quorum-sensing mutants.

    PubMed

    Majerczyk, Charlotte; Schneider, Emily; Greenberg, E Peter

    2016-01-01

    Burkholderia thailandensis uses acyl-homoserine lactone-mediated quorum sensing systems to regulate hundreds of genes. Here we show that cell-cell contact-dependent type VI secretion (T6S) toxin-immunity systems are among those activated by quorum sensing in B. thailandensis. We also demonstrate that T6S is required to constrain proliferation of quorum sensing mutants in colony cocultures of a BtaR1 quorum-sensing signal receptor mutant and its parent. However, the BtaR1 mutant is not constrained by and outcompetes its parent in broth coculture, presumably because no cell contact occurs and there is a metabolic cost associated with quorum sensing gene activation. The increased fitness of the wild type over the BtaR1 mutant during agar surface growth is dependent on an intact T6SS-1 apparatus. Thus, quorum sensing activates B. thailandensis T6SS-1 growth inhibition and this control serves to police and constrain quorum-sensing mutants. This work defines a novel role for T6SSs in intraspecies mutant control. PMID:27183270

  8. Fatigue Properties of Cast Magnesium Wheels

    NASA Astrophysics Data System (ADS)

    Li, Zhenming; Luo, Alan A.; Wang, Qigui; Peng, Liming; Zhang, Peng

    2016-08-01

    This paper investigates the fatigue properties and deformation behavior of a newly developed Mg-2.96Nd-0.21Zn-0.39Zr magnesium alloy wheel in both as-cast and T6 conditions. Compared with the as-cast alloy, the T6-treated alloy shows a significant increase in fatigue strength and cyclic stress amplitude. This is believed to be attributed to the change of defect type from porosity to oxides and the increased matrix strength in the T6 (peak-aged) condition. For the as-cast alloy wheel, fatigue failure mainly originated from the cast defects including porosity, oxide film, and inclusion at or near the sample surface. In the T6-treated alloy, however, oxides and inclusions or slip bands initiate the fatigue cracks. Solution treatment appears to reduce or eliminate the shrinkage porosity because of grain growth and dissolution of as-cast eutectic phases in the grain boundaries. The cyclic stress amplitude of the as-cast alloy increases with increasing the number of cycles, while the T6-treated alloy shows cyclic softening after the stress reaches a maximum value. The Coffin-Manson law and Basquin equation can be used to evaluate the life of low cycle fatigue. The developed long crack model and multi-scale fatigue (MSF) models can be used to predict high-cycle fatigue life of the Mg-2.96Nd-0.21Zn-0.39Zr alloys with or without casting defects.

  9. Quorum sensing control of Type VI secretion factors restricts the proliferation of quorum-sensing mutants

    PubMed Central

    Majerczyk, Charlotte; Schneider, Emily; Greenberg, E Peter

    2016-01-01

    Burkholderia thailandensis uses acyl-homoserine lactone-mediated quorum sensing systems to regulate hundreds of genes. Here we show that cell-cell contact-dependent type VI secretion (T6S) toxin-immunity systems are among those activated by quorum sensing in B. thailandensis. We also demonstrate that T6S is required to constrain proliferation of quorum sensing mutants in colony cocultures of a BtaR1 quorum-sensing signal receptor mutant and its parent. However, the BtaR1 mutant is not constrained by and outcompetes its parent in broth coculture, presumably because no cell contact occurs and there is a metabolic cost associated with quorum sensing gene activation. The increased fitness of the wild type over the BtaR1 mutant during agar surface growth is dependent on an intact T6SS-1 apparatus. Thus, quorum sensing activates B. thailandensis T6SS-1 growth inhibition and this control serves to police and constrain quorum-sensing mutants. This work defines a novel role for T6SSs in intraspecies mutant control. DOI: http://dx.doi.org/10.7554/eLife.14712.001 PMID:27183270

  10. Competence-induced type VI secretion might foster intestinal colonization by Vibrio cholerae: Intestinal interbacterial killing by competence-induced V. cholerae.

    PubMed

    Blokesch, Melanie

    2015-11-01

    The human pathogen Vibrio cholerae exhibits two distinct lifestyles: one in the aquatic environment where it often associates with chitinous surfaces and the other as the causative agent of the disease cholera. While much of the research on V. cholerae has focused on the host-pathogen interaction, knowledge about the environmental lifestyle of the pathogen remains limited. We recently showed that the polymer chitin, which is extremely abundant in aquatic environments, induces natural competence as a mode of horizontal gene transfer and that this competence regulon also includes the type VI secretion system (T6SS), a molecular killing device. Here, I discuss the putative consequences that chitin-induced T6SS activation could have on intestinal colonization and how the transmission route might influence disease outcome. Moreover, I propose that common infant animal models for cholera might not sufficiently take into account T6SS-mediated interbacterial warfare between V. cholerae and the intestinal microbiota. PMID:26445388

  11. Type VI secretion apparatus and phage tail-associated protein complexes share a common evolutionary origin

    SciTech Connect

    Leiman, Petr G.; Basler, Marek; Ramagopal, Udupi A.; Bonanno, Jeffrey B.; Sauder, J. Michael; Pukatzki, Stefan; Burley, Stephen K.; Almo, Steven C.; Mekalanos, John J.

    2009-04-22

    Protein secretion is a common property of pathogenic microbes. Gram-negative bacterial pathogens use at least 6 distinct extracellular protein secretion systems to export proteins through their multilayered cell envelope and in some cases into host cells. Among the most widespread is the newly recognized Type VI secretion system (T6SS) which is composed of 15--20 proteins whose biochemical functions are not well understood. Using crystallographic, biochemical, and bioinformatic analyses, we identified 3 T6SS components, which are homologous to bacteriophage tail proteins. These include the tail tube protein; the membrane-penetrating needle, situated at the distal end of the tube; and another protein associated with the needle and tube. We propose that T6SS is a multicomponent structure whose extracellular part resembles both structurally and functionally a bacteriophage tail, an efficient machine that translocates proteins and DNA across lipid membranes into cells.

  12. Aluminum alloy 6013 sheet for new U.S. Navy aircraft

    NASA Astrophysics Data System (ADS)

    Kaneko, R. S.; Bakow, L.; Lee, E. W.

    1990-05-01

    The recently developed aluminum alloy 6013-T6 has been selected for the fuselage skin and other applications on the U.S. Navy's P-7A airplane, in place of the traditional 2024-T3 clad sheet. Alloy 6013-T6 is naturally corrosion resistant, like the well-established alloy 6061, and hence is used unclad. Its fatigue strength, fatigue crack growth and fracture toughness compare favorably with 2024-T3. Replacement of alloy 2024 with alloy 6013 also reduces manufacturing costs for formed parts, because 6013 is readily formed in the T4 temper, then simply aged to T6, thus avoiding the costly heat treatments and straightening required for alloy 2024.

  13. Type VI secretion effectors: poisons with a purpose

    PubMed Central

    Russell, Alistair B.; Peterson, S. Brook; Mougous, Joseph D.

    2014-01-01

    The type VI secretion system (T6SS) mediates interactions between a diverse range of Gram-negative bacterial species. Recent studies have led to a drastic increase in the number of characterized T6SS effector proteins and produced a more complete and nuanced view of the adaptive significance of the system. While the system is most often implicated in antagonism, in this review we consider the case for its involvement in both antagonistic and non-antagonistic behaviors. Clarifying the roles that T6S plays in microbial communities will contribute to broader efforts to understand the importance of microbial interactions in maintaining human and environmental health, and will inform efforts to manipulate these interactions for therapeutic or environmental benefit. PMID:24384601

  14. An ABC transporter and an outer membrane lipoprotein participate in posttranslational activation of type VI secretion in Pseudomonas aeruginosa.

    PubMed

    Casabona, Maria G; Silverman, Julie M; Sall, Khady M; Boyer, Frédéric; Couté, Yohann; Poirel, Jessica; Grunwald, Didier; Mougous, Joseph D; Elsen, Sylvie; Attree, Ina

    2013-02-01

    Pseudomonas aeruginosa is capable of injecting protein toxins into other bacterial cells through one of its three type VI secretion systems (T6SSs). The activity of this T6SS is tightly regulated on the posttranslational level by phosphorylation-dependent and -independent pathways. The phosphorylation-dependent pathway consists of a Threonine kinase/phosphatase pair (PpkA/PppA) that acts on a forkhead domain-containing protein, Fha1, and a periplasmic protein, TagR, that positively regulates PpkA. In the present work, we biochemically and functionally characterize three additional proteins of the phosphorylation-dependent regulatory cascade that controls T6S activation: TagT, TagS and TagQ. We show that similar to TagR, these proteins act upstream of the PpkA/PppA checkpoint and influence phosphorylation of Fha1 and, apparatus assembly and effector export. Localization studies demonstrate that TagQ is an outer membrane lipoprotein and TagR is associated with the outer membrane. Consistent with their homology to lipoprotein outer membrane localization (Lol) components, TagT and TagS form a stable inner membrane complex with ATPase activity. However, we find that outer membrane association of T6SS lipoproteins TagQ and TssJ1, and TagR, is unaltered in a ΔtagTS background. Notably, we found that TagQ is indispensible for anchoring of TagR to the outer membrane fraction. As T6S-dependent fitness of P. aeruginosa requires TagT, S, R and Q, we conclude that these proteins likely participate in a trans-membrane signalling pathway that promotes H1-T6SS activity under optimal environmental conditions. PMID:22765374

  15. Monoclonal origin of B lymphocyte colony-forming cells in spleen colonies formed by multipotential hemopoietic stem cells

    PubMed Central

    Lala, PK; Johnson, GR

    1978-01-01

    Spleen colonies produced by transplanting lethally irradiated mice with either 12 day fetal liver or adult bone marrow cells were found to contain B- lymphocyte colony-forming cells (BL-CFC) . The proportion of BL-CFC positive spleen colonies did not increase substantially between 8 and 14 days after transplantation, the range being 18-45 percent. However, the absolute number of BL-CFC per spleen colony varied considerably (between 1 and 10,318), although the majority of colonies contained less than 200 BL-CFC. Irrespective of the time after transplantation, smaller spleen colonies were found to have a higher frequency of BL-CFC than larger spleen colonies. To determine the possible clonal origin of BL-CFC from spleen colony- forming unit (CFU-S), CBA mice were injected with equal numbers of CBA and CBA T(6)/T(6) fetal liver or adult bone marrow cells. Analysis of 7-15-day spleen colonies demonstrated that 90 percent were either exclusively T(6) positive or T(6) negative and approximately equal numbers ofboth colony types were observed. B-lymphocyte colonies were grown and successfully karyotyped from 19 spleen colonies. When compared with the original spleen colony karyotype the B-lymphocyte colony cells karyotype was identical in all 19 cases. In 3 of the 19 colonies analyzed a mixture of T(6) positive and T(6) negative karyotypes was present and identical proportions of the karyotypes were present in the pooled B-lymphocyte colony cells and spleen colony cells. The data indicate that the B-lymphocyte colony-forming cells detected in spleen colonies are genuine members of the hemopoietic clone derived from the initiating hemopoietic stem cell (CFU-S). PMID:309918

  16. Fha Interaction with Phosphothreonine of TssL Activates Type VI Secretion in Agrobacterium tumefaciens

    PubMed Central

    Lin, Jer-Sheng; Wu, Hsin-Hui; Hsu, Pang-Hung; Ma, Lay-Sun; Pang, Yin-Yuin; Tsai, Ming-Daw; Lai, Erh-Min

    2014-01-01

    The type VI secretion system (T6SS) is a widespread protein secretion system found in many Gram-negative bacteria. T6SSs are highly regulated by various regulatory systems at multiple levels, including post-translational regulation via threonine (Thr) phosphorylation. The Ser/Thr protein kinase PpkA is responsible for this Thr phosphorylation regulation, and the forkhead-associated (FHA) domain-containing Fha-family protein is the sole T6SS phosphorylation substrate identified to date. Here we discovered that TssL, the T6SS inner-membrane core component, is phosphorylated and the phosphorylated TssL (p-TssL) activates type VI subassembly and secretion in a plant pathogenic bacterium, Agrobacterium tumefaciens. Combining genetic and biochemical approaches, we demonstrate that TssL is phosphorylated at Thr 14 in a PpkA-dependent manner. Further analysis revealed that the PpkA kinase activity is responsible for the Thr 14 phosphorylation, which is critical for the secretion of the T6SS hallmark protein Hcp and the putative toxin effector Atu4347. TssL phosphorylation is not required for the formation of the TssM-TssL inner-membrane complex but is critical for TssM conformational change and binding to Hcp and Atu4347. Importantly, Fha specifically interacts with phosphothreonine of TssL via its pThr-binding motif in vivo and in vitro and this interaction is crucial for TssL interaction with Hcp and Atu4347 and activation of type VI secretion. In contrast, pThr-binding ability of Fha is dispensable for TssM structural transition. In conclusion, we discover a novel Thr phosphorylation event, in which PpkA phosphorylates TssL to activate type VI secretion via its direct binding to Fha in A. tumefaciens. A model depicting an ordered TssL phosphorylation-induced T6SS assembly pathway is proposed. PMID:24626341

  17. Contribution of the Type VI Secretion System Encoded in SPI-19 to Chicken Colonization by Salmonella enterica Serotypes Gallinarum and Enteritidis

    PubMed Central

    Blondel, Carlos J.; Yang, Hee-Jeong; Castro, Benjamín; Chiang, Sebastián; Toro, Cecilia S.; Zaldívar, Mercedes; Contreras, Inés; Andrews-Polymenis, Helene L.; Santiviago, Carlos A.

    2010-01-01

    Salmonella Gallinarum is a pathogen with a host range specific to poultry, while Salmonella Enteritidis is a broad host range pathogen that colonizes poultry sub-clinically but is a leading cause of gastrointestinal salmonellosis in humans and many other species. Despite recent advances in our understanding of the complex interplay between Salmonella and their hosts, the molecular basis of host range restriction and unique pathobiology of Gallinarum remain largely unknown. Type VI Secretion System (T6SS) represents a new paradigm of protein secretion that is critical for the pathogenesis of many Gram-negative bacteria. We recently identified a putative T6SS in the Salmonella Pathogenicity Island 19 (SPI-19) of Gallinarum. In Enteritidis, SPI-19 is a degenerate element that has lost most of the T6SS functions encoded in the island. In this work, we studied the contribution of SPI-19 to the colonization of Salmonella Gallinarum strain 287/91 in chickens. Non-polar deletion mutants of SPI-19 and the clpV gene, an essential T6SS component, colonized the ileum, ceca, liver and spleen of White Leghorn chicks poorly compared to the wild-type strain after oral inoculation. Return of SPI-19 to the ΔSPI-19 mutant, using VEX-Capture, complemented this colonization defect. In contrast, transfer of SPI-19 from Gallinarum to Enteritidis resulted in transient increase in the colonization of the ileum, liver and spleen at day 1 post-infection, but at days 3 and 5 post-infection a strong colonization defect of the gut and internal organs of the experimentally infected chickens was observed. Our data indicate that SPI-19 and the T6SS encoded in this region contribute to the colonization of the gastrointestinal tract and internal organs of chickens by Salmonella Gallinarum and suggest that degradation of SPI-19 T6SS in Salmonella Enteritidis conferred an advantage in colonization of the avian host. PMID:20661437

  18. The Type VI Secretion TssEFGK-VgrG Phage-Like Baseplate Is Recruited to the TssJLM Membrane Complex via Multiple Contacts and Serves As Assembly Platform for Tail Tube/Sheath Polymerization

    PubMed Central

    Boyer, Frédéric; Douzi, Badreddine; Cascales, Eric

    2015-01-01

    The Type VI secretion system (T6SS) is a widespread weapon dedicated to the delivery of toxin proteins into eukaryotic and prokaryotic cells. The 13 T6SS subunits assemble a cytoplasmic contractile structure anchored to the cell envelope by a membrane-spanning complex. This structure is evolutionarily, structurally and functionally related to the tail of contractile bacteriophages. In bacteriophages, the tail assembles onto a protein complex, referred to as the baseplate, that not only serves as a platform during assembly of the tube and sheath, but also triggers the contraction of the sheath. Although progress has been made in understanding T6SS assembly and function, the composition of the T6SS baseplate remains mostly unknown. Here, we report that six T6SS proteins–TssA, TssE, TssF, TssG, TssK and VgrG–are required for proper assembly of the T6SS tail tube, and a complex between VgrG, TssE,-F and-G could be isolated. In addition, we demonstrate that TssF and TssG share limited sequence homologies with known phage components, and we report the interaction network between these subunits and other baseplate and tail components. In agreement with the baseplate being the assembly platform for the tail, fluorescence microscopy analyses of functional GFP-TssF and TssK-GFP fusion proteins show that these proteins assemble stable and static clusters on which the sheath polymerizes. Finally, we show that recruitment of the baseplate to the apparatus requires initial positioning of the membrane complex and contacts between TssG and the inner membrane TssM protein. PMID:26460929

  19. Structure of the Trehalose-6-phosphate Phosphatase from Brugia malayi Reveals Key Design Principles for Anthelmintic Drugs

    PubMed Central

    Farelli, Jeremiah D.; Galvin, Brendan D.; Li, Zhiru; Liu, Chunliang; Aono, Miyuki; Garland, Megan; Hallett, Olivia E.; Causey, Thomas B.; Ali-Reynolds, Alana; Saltzberg, Daniel J.; Carlow, Clotilde K. S.; Dunaway-Mariano, Debra; Allen, Karen N.

    2014-01-01

    Parasitic nematodes are responsible for devastating illnesses that plague many of the world's poorest populations indigenous to the tropical areas of developing nations. Among these diseases is lymphatic filariasis, a major cause of permanent and long-term disability. Proteins essential to nematodes that do not have mammalian counterparts represent targets for therapeutic inhibitor discovery. One promising target is trehalose-6-phosphate phosphatase (T6PP) from Brugia malayi. In the model nematode Caenorhabditis elegans, T6PP is essential for survival due to the toxic effect(s) of the accumulation of trehalose 6-phosphate. T6PP has also been shown to be essential in Mycobacterium tuberculosis. We determined the X-ray crystal structure of T6PP from B. malayi. The protein structure revealed a stabilizing N-terminal MIT-like domain and a catalytic C-terminal C2B-type HAD phosphatase fold. Structure-guided mutagenesis, combined with kinetic analyses using a designed competitive inhibitor, trehalose 6-sulfate, identified five residues important for binding and catalysis. This structure-function analysis along with computational mapping provided the basis for the proposed model of the T6PP-trehalose 6-phosphate complex. The model indicates a substrate-binding mode wherein shape complementarity and van der Waals interactions drive recognition. The mode of binding is in sharp contrast to the homolog sucrose-6-phosphate phosphatase where extensive hydrogen-bond interactions are made to the substrate. Together these results suggest that high-affinity inhibitors will be bi-dentate, taking advantage of substrate-like binding to the phosphoryl-binding pocket while simultaneously utilizing non-native binding to the trehalose pocket. The conservation of the key residues that enforce the shape of the substrate pocket in T6PP enzymes suggest that development of broad-range anthelmintic and antibacterial therapeutics employing this platform may be possible. PMID:24992307

  20. Methanogenic activity inhibition by increasing the linear alkylbenzene sulfonate (LAS) concentration.

    PubMed

    Souza, Luiza F C; Florencio, Lourdinha; Gavazza, Savia; Kato, Mario T

    2016-07-01

    The effect of the initial concentration of linear alkylbenzene sulfonate (LAS) on specific methanogenic activity (SMA) was investigated in this work. Six anaerobic flasks reactors with 1 L of total volume were inoculated with anaerobic sludge (2 g VSS L(-1)). The reactors were assayed for 42 days, and fed with volatile fatty acids, nutrients, and LAS. The initial LAS concentrations were 0, 10, 30, 50, 75, and 100 mg L(-1) for the treatment flasks T1 (control), T2, T3, T4, T5, and T6, respectively. When compared with T1, T2 exhibited a 30% reduction in maximum SMA and total methane production (TMP). In treatment T3 through T6, the reductions were 44-97% (T3-T6) for SMA, and 30-90% (T3-T6) for TMP. Total LAS removal increased following the increase in the initial LAS concentration (from 36% at T1 to 76% at T6), primarily due to the high degree of sludge adsorption. LAS biodegradation also occurred (32% in all treatments), although this was most likely associated with the formation of non-methane intermediates. Greater removal by adsorption was observed in long-chain homologues, when compared to short-chain homologues (C13 > C10), whereas the opposite occurred for biodegradation (C10 > C13). The C13 homologue was adsorbed to a great extent (in mass) in T4, T5 and T6, and may also have inhibited methane formation in these treatments. PMID:27088975

  1. An in-situ study in SEM of delamination in several graphite/epoxy composite material systems

    NASA Technical Reports Server (NTRS)

    Bradley, W. L.

    1986-01-01

    A three point bend fixture compatible with the current loading stage for the Scanning Electron Microscope was designed and fabricated. End-notched flexure tests were run on several materials. Work to date was on AS4/3502, T6T145/F155, and T6T145/F185. Fracture toughness was measured. Fracture of neat resin specimens was begun. The decrease in delaminatin fracture toughness, compared to neat resin toughness, due to rigid fiber filler and interlaminar failure is addressed. An experimental program was designed to try to determine the proper interpretatin for apparent microcracking in neat resin specimens.

  2. TGF-β1-elevated TRPM7 channel regulates collagen expression in hepatic stellate cells via TGF-β1/Smad pathway

    SciTech Connect

    Fang, Ling; Huang, Cheng; Meng, Xiaoming; Wu, Baoming; Ma, Taotao; Liu, Xuejiao; Zhu, Qian; Zhan, Shuxiang; Li, Jun

    2014-10-15

    Transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts plays a critical role in the development of liver fibrosis, since myofibroblasts are the key cells responsible for excessive deposition of ECM proteins. Transient receptor potential melastatin 7 (TRPM7), a non-selective cation channel with protein serine/threonine kinase activity, has been demonstrated to function in the proliferation of activated HSCs. Here, we investigated the functional role of TRPM7 in collagen deposition in activated HSC-T6 cells (a rat hepatic stellate cell line). TRPM7 mRNA and protein were measured by Real-time PCR and Western blot in TGF-β1-activated HSC-T6 cells in vitro. Results demonstrated that TRPM7 protein was dramatically increased in fibrotic human livers. Stimulation of HSC-T6 cells with TGF-β1 increased TRPM7 mRNA and protein level in a time-dependent manner. Nevertheless, TGF-β1-elicited upregulation of TRPM7 in HSC-T6 cells was abrogated by SB431542 (TGF-β1 receptor blocker) or SIS3 (inhibitor of Smad3 phosphorylation). Additionally, blockade of TRPM7 channels with non-specific TRPM7 blocker 2-APB or synthetic siRNA targeting TRPM7 attenuated TGF-β1-induced expression of myofibroblast markers, as measured by the induction of α-SMA and Col1α1. Silencing TRPM7 also increased the ratio of MMPs/TIMPs by increasing MMP-13 expression and decreasing TIMP-1 and TIMP-2 levels. Strikingly, phosphorylation of p-Smad2 and p-Smad3, associated with collagen production, was decreased in TRPM7 deficient HSC-T6 cells. These observations suggested that TGF-β1 elevates TRPM7 expression in HSCs via Smad3-dependant mechanisms, which in turn contributes Smad protein phosphorylation, and subsequently increases fibrous collagen expression. Therefore, TRPM7 may constitute a useful target for the treatment of liver fibrosis. - Highlights: • Upregulation of TRPM7 protein in human fibrotic livers • Upregulation of TRPM7 by TGF-β1 elicited Smad signaling in HSC-T6 cells

  3. TRPM7 channel regulates PDGF-BB-induced proliferation of hepatic stellate cells via PI3K and ERK pathways

    SciTech Connect

    Fang, Ling Zhan, Shuxiang; Huang, Cheng; Cheng, Xi; Lv, Xiongwen; Si, Hongfang; Li, Jun

    2013-11-01

    TRPM7, a non-selective cation channel of the TRP channel superfamily, is implicated in diverse physiological and pathological processes including cell proliferation. Recently, TRPM7 has been reported in hepatic stellate cells (HSCs). Here, we investigated the contribution role of TRPM7 in activated HSC-T6 cell (a rat hepatic stellate cell line) proliferation. TRPM7 mRNA and protein were measured by RT-PCR and Western blot in rat model of liver fibrosis in vivo and PDGF-BB-activated HSC-T6 cells in vitro. Both mRNA and protein of TRPM7 were dramatically increased in CCl{sub 4}-treated rat livers. Stimulation of HSC-T6 cells with PDGF-BB resulted in a time-dependent increase of TRPM7 mRNA and protein. However, PDGF-BB-induced HSC-T6 cell proliferation was inhibited by non-specific TRPM7 blocker 2-aminoethoxydiphenyl borate (2-APB) or synthetic siRNA targeting TRPM7, and this was accompanied by downregulation of cell cycle proteins, cyclin D1, PCNA and CDK4. Blockade of TRPM7 channels also attenuated PDGF-BB induced expression of myofibroblast markers as measured by the induction of α-SMA and Col1α1. Furthermore, the phosphorylation of ERK and AKT, associated with cell proliferation, decreased in TRPM7 deficient HSC-T6 cells. These observations suggested that TRPM7 channels contribute to perpetuated fibroblast activation and proliferation of PDGF-BB induced HSC-T6 cells via the activation of ERK and PI3K pathways. Therefore, TRPM7 may constitute a useful target for the treatment of liver fibrosis. - Highlights: • Upregulation of TRPM7 mRNA and protein in the fibrotic livers from CCl{sub 4}-treated rats. • Increasing expression of TRPM7 mRNA and protein during HSC activation. • Blockade of TRPM7 inhibited the PDGF-BB induced proliferation of HSC-T6 cells. • Blockade of TRPM7 decreased α-SMA and Col1α1 expressions in activated HSC-T6 cells. • TRPM7 up-regulation contributes to the activation of ERK and AKT pathways.

  4. Microstates of a neutral black hole in M theory.

    PubMed

    Emparan, Roberto; Horowitz, Gary T

    2006-10-01

    We consider vacuum solutions in M theory of the form of a five-dimensional Kaluza-Klein black hole cross T6. In a certain limit, these include the five-dimensional neutral rotating black hole (cross T6). From a type-IIA standpoint, these solutions carry D0 and D6 charges. We show that there is a simple D-brane description which precisely reproduces the Hawking-Bekenstein entropy in the extremal limit, even though supersymmetry is completely broken. PMID:17155239

  5. Rapidly solidified metal coatings by peen plating

    NASA Technical Reports Server (NTRS)

    Chu, H. P.

    1987-01-01

    Specimens of 7075-T6 aluminum alloy were peen plated with rapidly solidified tin-lead and aluminum powders, and the cross-sections of the coated specimens were examined by light and electron microscopy. The properties of the peen plated specimens were also compared with those of shot peened specimens without any coating. It is found that peen plating with rapidly solidified metals improves the fatigue properties of the coated samples to a greater extent than shot peening alone. Specimens of 7075-T6 alloy peen plated with rapidly solidified tin-lead and aluminum exhibited better fatigue resistance than shot peened specimens in both air and salt water.

  6. Inhibition of Type VI Secretion by an Anti-TssM Llama Nanobody

    PubMed Central

    Spinelli, Silvia; Desmyter, Aline; Le, Thi Thu Hang; Kellenberger, Christine; Douzi, Badreddine; Durand, Eric; Roussel, Alain; Cascales, Eric; Cambillau, Christian

    2015-01-01

    The type VI secretion system (T6SS) is a secretion pathway widespread in Gram-negative bacteria that targets toxins in both prokaryotic and eukaryotic cells. Although most T6SSs identified so far are involved in inter-bacterial competition, a few are directly required for full virulence of pathogens. The T6SS comprises 13 core proteins that assemble a large complex structurally and functionally similar to a phage contractile tail structure anchored to the cell envelope by a trans-membrane spanning stator. The central part of this stator, TssM, is a 1129-amino-acid protein anchored in the inner membrane that binds to the TssJ outer membrane lipoprotein. In this study, we have raised camelid antibodies against the purified TssM periplasmic domain. We report the crystal structure of two specific nanobodies that bind to TssM in the nanomolar range. Interestingly, the most potent nanobody, nb25, competes with the TssJ lipoprotein for TssM binding in vitro suggesting that TssJ and the nb25 CDR3 loop share the same TssM binding site or causes a steric hindrance preventing TssM-TssJ complex formation. Indeed, periplasmic production of the nanobodies displacing the TssM-TssJ interaction inhibits the T6SS function in vivo. This study illustrates the power of nanobodies to specifically target and inhibit bacterial secretion systems. PMID:25811612

  7. A new fauna from the Colorado group of southern Montana

    USGS Publications Warehouse

    Reeside, John B., Jr.

    1925-01-01

    This paper describes a small but interesting fauna collected in 1921 by W. T. Thorn, Jr., Gail F. Moulton, T. W. Stanton, and K. C. Heald in the Crow Indian Reservation in southern Montana. The locality is in sec. 36, T. 6 S., R. 32 E., Big Horn County, and is 2 miles east of the Soap Creek oil field.

  8. Roles of Hcp family proteins in the pathogenesis of the porcine extraintestinal pathogenic Escherichia coli type VI secretion system.

    PubMed

    Peng, Ying; Wang, Xiangru; Shou, Jin; Zong, Bingbing; Zhang, Yanyan; Tan, Jia; Chen, Jing; Hu, Linlin; Zhu, Yongwei; Chen, Huanchun; Tan, Chen

    2016-01-01

    Hcp (hemolysin-coregulated protein) is considered a vital component of the functional T6SS (Type VI Secretion System), which is a newly discovered secretion system. Our laboratory has previously sequenced the whole genome of porcine extraintestinal pathogenic E. coli (ExPEC) strain PCN033, and identified an integrated T6SS encoding three different hcp family genes. In this study, we first identified a functional T6SS in porcine ExPEC strain PCN033, and demonstrated that the Hcp family proteins were involved in bacterial competition and the interactions with other cells. Interestingly, the three Hcp proteins had different functions. Hcp2 functioned predominantly in bacterial competition; all three proteins were involved in the colonization of mice; and Hcp1 and Hcp3 were predominantly contributed to bacterial-eukaryotic cell interactions. We showed an active T6SS in porcine ExPEC strain PCN033, and the Hcp family proteins had different functions in their interaction with other bacteria or host cells. PMID:27229766

  9. SURVIVAL OF NORTH AMERICAN GENOTYPES OF TRICHINELLA IN FROZEN PORK

    Technology Transfer Automated Retrieval System (TEKTRAN)

    North American genotypes of Trichinella (T. nativa (T-2), T. pseudospiralis (T-4), T. murrelli (T-5), and Trichinella (T-6)) were examined for susceptibility to freezing in pork using established parameters for control of T. spiralis. Pig infections with these Trichinella genotypes were established ...

  10. Type VI secretion system translocates a phage tail spike-like protein into target cells where it cross-links actin

    PubMed Central

    Pukatzki, Stefan; Ma, Amy T.; Revel, Andrew T.; Sturtevant, Derek; Mekalanos, John J.

    2007-01-01

    Genes encoding type VI secretion systems (T6SS) are widely distributed in pathogenic Gram-negative bacterial species. In Vibrio cholerae, T6SS have been found to secrete three related proteins extracellularly, VgrG-1, VgrG-2, and VgrG-3. VgrG-1 can covalently cross-link actin in vitro, and this activity was used to demonstrate that V. cholerae can translocate VgrG-1 into macrophages by a T6SS-dependent mechanism. Protein structure search algorithms predict that VgrG-related proteins likely assemble into a trimeric complex that is analogous to that formed by the two trimeric proteins gp27 and gp5 that make up the baseplate “tail spike” of Escherichia coli bacteriophage T4. VgrG-1 was shown to interact with itself, VgrG-2, and VgrG-3, suggesting that such a complex does form. Because the phage tail spike protein complex acts as a membrane-penetrating structure as well as a conduit for the passage of DNA into phage-infected cells, we propose that the VgrG components of the T6SS apparatus may assemble a “cell-puncturing device” analogous to phage tail spikes to deliver effector protein domains through membranes of target host cells. PMID:17873062

  11. The feasibility of producing aluminum-lithium structures for cryogenic tankage applications by laser beam welding

    NASA Technical Reports Server (NTRS)

    Martukanitz, R. P.; Lysher, K. G.

    1993-01-01

    Aluminum-lithium alloys exhibit high strength, high elastic modulus, and low density as well as excellent cryogenic mechanical properties making them ideal material candidates for cryogenic tanks. NASA has proposed the use of 'built-up' structure for panels fabricated into cryogenic tanks replacing current conventional machining. Superplastically formed stiffeners would be joined to sheet (tank skin) that had been roll formed to the radius of the tank in order to produce panels. Aluminum-lithium alloys of interest for producing the built-up structure include alloy 2095-T6 stiffeners to 2095-T8 sheet and alloy 8090-T6 stiffeners to 2090-T83 sheet. Laser welding, with comparable joint properties, offers the following advantages over conventional welding: higher production rates, minimal degradation within the heat affected zones, and full process automation. This study established process parameters for laser beam welding, mechanical property determinations, metallographic characterization, and fabrication of prototype panels. Tensile tests representing partial penetration of the skin alloys provided joint efficiencies between 65 and 77 percent, depending upon alloy and degree of penetration. Results of tension shear tests of lap welds indicated that the combination of 2095-T6 to 2090-T8 exhibited significantly higher weld shear strength at the interface in comparison to welds of 8090-T6 to 2090-T83. The increased shear strength associated with 2095 is believed to be due to the alloy's ability to precipitation strengthening (naturally age) after welding.

  12. The Pseudomonas aeruginosa Type VI Secretion PGAP1-like Effector Induces Host Autophagy by Activating Endoplasmic Reticulum Stress.

    PubMed

    Jiang, Feng; Wang, Xia; Wang, Bei; Chen, Lihong; Zhao, Zhendong; Waterfield, Nicholas R; Yang, Guowei; Jin, Qi

    2016-08-01

    Pseudomonas aeruginosa is an opportunistic pathogen that regularly causes nosocomial infections in hospitalized patients. The type VI secretion system (T6SS) is responsible for the secretion of numerous virulence effector proteins that can both interfere with competing microbes and manipulate host cells. Here, we report a detailed investigation of a P. aeruginosa H2-T6SS-dependent phospholipase effector, TplE, which acts as a trans-kingdom toxin. Delivery of TplE to the periplasmic space of rival bacteria leads to growth inhibition. Importantly, TplE, also contains a eukaryotic PGAP1-like domain, which targets the host ER apparatus, ultimately leading to disruption of the ER. TplE activity leads to the activation of the unfolded protein response (UPR) through the IRE1α-XBP1 pathway, enhancing autophagic flux. These findings indicate that this T6SS-delivered phospholipase effector is active against both prokaryotic and eukaryotic cellular targets, highlighting the T6SS as a versatile weapon in the Pseudomonas arsenal. PMID:27477276

  13. Tests Of Polyurethane And Dichromate Coats On Aluminum

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1992-01-01

    Report describes experiments to determine relative effectiveness of new polyurethane and more-conventional dichromate coat in helping to retard corrosion of anodized 6061-T6 aluminum. Concludes by suggesting greater protection against corrosion achieved by combining polyurethane-sealing method with hard-anodizing method and by increasing thickness of coat.

  14. Mechanical Property and Intergranular Corrosion Sensitivity of Zn-Free and Zn-Microalloyed Al-2.7Cu-1.7Li-0.3Mg Alloys

    NASA Astrophysics Data System (ADS)

    Li, Jin-feng; Xu, Long; Cai, Chao; Chen, Yong-lai; Zhang, Xu-hu; Zheng, Zi-qiao

    2014-11-01

    The influence of 0.72 pct Zn addition on the tensile properties of Al-2.7Cu-1.7Li-0.3Mg alloys was investigated. Their intergranular corrosion (IGC) dependence on aging [T6 type at 423 K (150 °C) and 448 K (175 °C) and T8 type at 423 K (150 °C)] time was studied. An IGC diagram associated with aging process was established. The addition of 0.72 pct Zn enhanced the strength of the Al-Li alloy with T6 type aging at 448 K (175 °C). With aging process, the corrosion mode of the T6-aged Al-Li alloys was changed in the following order: pitting and local IGC (initial aging stage), general IGC (underaging stage), local IGC (near peak-aging stage), and pitting (overaging stage) again. The IGC depth was increased first and then decreased with aging time extension. The corrosion potential change of grains and the microstructure variation were used to explain the IGC sensitivity of the Al-Li alloy with different tempers. Meanwhile, 0.72 pct Zn addition decreased the IGC sensitivity of the Al-Li alloy, especially the T6-aged Al-Li alloy.

  15. Mechanical Property and Intergranular Corrosion Sensitivity of Zn-Free and Zn-Microalloyed Al-2.7Cu-1.7Li-0.3Mg Alloys

    NASA Astrophysics Data System (ADS)

    Li, Jin-feng; Xu, Long; Cai, Chao; Chen, Yong-lai; Zhang, Xu-hu; Zheng, Zi-qiao

    2014-09-01

    The influence of 0.72 pct Zn addition on the tensile properties of Al-2.7Cu-1.7Li-0.3Mg alloys was investigated. Their intergranular corrosion (IGC) dependence on aging [T6 type at 423 K (150 °C) and 448 K (175 °C) and T8 type at 423 K (150 °C)] time was studied. An IGC diagram associated with aging process was established. The addition of 0.72 pct Zn enhanced the strength of the Al-Li alloy with T6 type aging at 448 K (175 °C). With aging process, the corrosion mode of the T6-aged Al-Li alloys was changed in the following order: pitting and local IGC (initial aging stage), general IGC (underaging stage), local IGC (near peak-aging stage), and pitting (overaging stage) again. The IGC depth was increased first and then decreased with aging time extension. The corrosion potential change of grains and the microstructure variation were used to explain the IGC sensitivity of the Al-Li alloy with different tempers. Meanwhile, 0.72 pct Zn addition decreased the IGC sensitivity of the Al-Li alloy, especially the T6-aged Al-Li alloy.

  16. Influence of homogenization and artificial aging heat treatments on corrosion behavior of Mg-Al alloys

    SciTech Connect

    Beldjoudi, T.; Fiaud, C.; Robbiola, L. . Lab. d'Etudes de la Corrosion)

    1993-09-01

    The influence of heat treatment on corrosion behavior of magnesium-aluminum (Mg-9Al) alloys was investigated by studying the electrochemical properties of Mg-9Al in the solution-treated (T4) and artificially aged (T6) conditions. The alloys' properties were compared to those of pure Mg, the intermetallic Mg[sub 17]Al[sub 12] phase, and different Mg-Al-based alloys (Mg-3Al, AZ91). The Mg-9Al alloy exhibited better corrosion resistance in the T6 condition than in the T4 condition because of the intermetallic Mg[sub 17]Al[sub 12] precipitates present n the T6 alloy. The mechanism responsible for this behavior was attributed to a more protective porous film on the T6 matrix alloy than on the T4 alloy. Addition of zinc did not modify these results. Localized corrosion testing showed the Mg-Al alloys were attacked preferentially in relation to magnesium silicide (Mg[sub 2]Si) precipitates which were characterized clearly using metallurgical examinations.

  17. A highly sensitive and selective immunoassay for the detection of tetrabromobisphenol A in soil and sediment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant. A sensitive and selective enzyme-linked immunosorbent assay (ELISA) for the detection of TBBPA was developed. Six haptens (T1-T6) mimicking different structural elements of TBBPA were synthesized and coupled to keyhole...

  18. Biotechnology Process Engineering Center at MIT Home

    Science.gov Websites

    ... &22; )&25;&2;tt &6; - &8; &22; )&28; p:www.w3. &6; - &8; &22; (&2;&6;&3;&1;o &6; - &8; &22; )&25; rgTRREC )&1;- &6; &1; - &8; &22; Q )&17;&1;h &6; - &8; &22; )&25;&1;t &6; &2; - &8; &1; &22; )&14;&1;m &6; &1; - ...

  19. The Professional Status of Teachers: Some Theoretical Concerns and Ontario Survey

    ERIC Educational Resources Information Center

    Fris, Joe

    1975-01-01

    This paper is designed to help clarify thinking about professionalism and the process of professionalization and to report the status of a study that attempted to assess the professional status of secondary school teachers in Ontario. (Published by Department of Educational Administration, University of Alberta, Edmonton, Alberta T6G 2E1) (Author)

  20. Diversity of Clinical and Environmental Isolates of Vibrio cholerae in Natural Transformation and Contact-Dependent Bacterial Killing Indicative of Type VI Secretion System Activity.

    PubMed

    Bernardy, Eryn E; Turnsek, Maryann A; Wilson, Sarah K; Tarr, Cheryl L; Hammer, Brian K

    2016-05-01

    The bacterial pathogenVibrio choleraecan occupy both the human gut and aquatic reservoirs, where it may colonize chitinous surfaces that induce the expression of factors for three phenotypes: chitin utilization, DNA uptake by natural transformation, and contact-dependent bacterial killing via a type VI secretion system (T6SS). In this study, we surveyed a diverse set of 53 isolates from different geographic locales collected over the past century from human clinical and environmental specimens for each phenotype outlined above. The set included pandemic isolates of serogroup O1, as well as several serogroup O139 and non-O1/non-O139 strains. We found that while chitin utilization was common, only 22.6% of the isolates tested were proficient at chitin-induced natural transformation, suggesting that transformation is expendable. Constitutive contact-dependent killing ofEscherichia coliprey, which is indicative of a functional T6SS, was rare among clinical isolates (only 4 of 29) but common among environmental isolates (22 of 24). These results bolster the pathoadaptive model in which tight regulation of T6SS-mediated bacterial killing is beneficial in a human host, whereas constitutive killing by environmental isolates may give a competitive advantage in natural settings. Future sequence analysis of this set of diverse isolates may identify previously unknown regulators and structural components for both natural transformation and T6SS. PMID:26944842

  1. Type VI Secretion: not just for pathogenesis anymore

    PubMed Central

    Jani, Andrea J.; Cotter, Peggy A.

    2010-01-01

    Summary Type VI Secretion Systems (T6SS) have been studied primarily in the context of pathogenic bacterial-host interactions. Recent data suggest, however, that these versatile secretion systems may also function to promote commensal or mutualistic relationships between bacteria and eukaryotes, or to mediate cooperative or competitive interactions between bacteria. PMID:20638635

  2. Evaluating of NASA-Langley Research Center explosion seam welding

    NASA Technical Reports Server (NTRS)

    Otto, H. E.; Wittman, R.

    1977-01-01

    An explosion bonding technique to meet current fabrication requirements was demonstrated. A test program was conducted on explosion bonded joints, compared to fusion joints in 6061-T6 aluminum. The comparison was made in required fixtures, non-destructive testing, static strength and fatigue strength.

  3. School Size, Cost and Quality

    ERIC Educational Resources Information Center

    Ratsoy, Eugene W.; Bumbarger, Chester S.

    1976-01-01

    Despite the trend toward consolidation of schools, many small schools continue to exist. The challenge is to identify and implement the changes that will improve these schools. (Available from Canadian Administrator Business Manager, Department of Educational Administration, The University of Alberta, Edmonton, Alberta, Canada T6G 2G5; $0.50…

  4. Educational Vouchers

    ERIC Educational Resources Information Center

    Pickard, Brent W.; Richards, Donald M.

    1976-01-01

    Summarizes the rationale for educational voucher systems, outlines model voucher systems, discusses implications of voucher systems, and suggests a generalized plan for applying voucher systems in continuing education. (Available from the Department of Educational Administration, The University of Alberta, Edmonton, Alberta, Canada, T6G 2G5;…

  5. Professional Role Orientation of Women Administrators and Women Teachers

    ERIC Educational Resources Information Center

    Nixon, Mary; Gue, L. R.

    1975-01-01

    The professional role orientation of women teachers and women administrators is compared with a limited number of variables. (Available from the Department of Educational Administration, The University of Alberta, Edmonton, Canada T6G 2G5; $4.00 annually.) (MLF)

  6. Administering the Open-Area Elementary School

    ERIC Educational Resources Information Center

    Small, J. M.

    1975-01-01

    Examines the outcome of a study of the operation of open area schools in the Separate School System of Edmonton. (Available from C. A. Business Manager, Department of Educational Administration, The University of Alberta, Edmonton, Alberta, Canada T6G 2G5; $0.50, single copy.) (Author/IRT)

  7. Indian Government and Indian Education.

    ERIC Educational Resources Information Center

    Starblanket, Noel V.

    1981-01-01

    Accountability for Indian education must be shared among the chiefs and their councils, the Indian leaders at all levels, parents and students. This may be accomplished by Indian control of Indian education. Available from: Department of Educational Foundations, 5-109 Education North, University of Alberta, Edmonton, AB, Canada, T6G 2G5. (ERB)

  8. The Role of the Native Woman in a Native Society.

    ERIC Educational Resources Information Center

    Swampy, Grace Marie

    1982-01-01

    Eighteen Plains Cree-speaking women, aged 15-93, were interviewed to determine the persistence of traditional beliefs as they affect the role of women. "The major implication is that the culture is alive." Available: Department of Educational Foundations, 5-109 Education North, University of Alberta, Edmonton, Alberta, Canada, T6G 2G5. (LC)

  9. Militancy and Accommodativeness in Teachers' Negotiations: Two Ontario Surveys

    ERIC Educational Resources Information Center

    Fris, J.

    1976-01-01

    Reports findings of two surveys of Ontario elementary and secondary teachers that measured teachers' attitudes regarding collective bargaining tactics and classified teachers' responses according to their militancy or accomodativeness. Available from Department of Educational Administration, The University of Alberta, Edmonton, Alberta, Canada T6G…

  10. Teachers' Aides: Tasks and Concerns

    ERIC Educational Resources Information Center

    Balderson, James H.; Nixon, Mary

    1976-01-01

    Addresses three questions: (1) What tasks do aides perform? (2) Does training make a difference in the type of tasks aides perform? (3) What are the concerns of aides? (Available from the Department of Educational Administration, The University of Alberta, Edmonton, Alberta, Canada T6G 2G5; $0.50, single copy.) (Author/IRT)

  11. A phospholipase A1 antibacterial Type VI secretion effector interacts directly with the C-terminal domain of the VgrG spike protein for delivery.

    PubMed

    Flaugnatti, Nicolas; Le, Thi Thu Hang; Canaan, Stéphane; Aschtgen, Marie-Stéphanie; Nguyen, Van Son; Blangy, Stéphanie; Kellenberger, Christine; Roussel, Alain; Cambillau, Christian; Cascales, Eric; Journet, Laure

    2016-03-01

    The Type VI secretion system (T6SS) is a multiprotein machine that delivers protein effectors in both prokaryotic and eukaryotic cells, allowing interbacterial competition and virulence. The mechanism of action of the T6SS requires the contraction of a sheath-like structure that propels a needle towards target cells, allowing the delivery of protein effectors. Here, we provide evidence that the entero-aggregative Escherichia coli Sci-1 T6SS is required to eliminate competitor bacteria. We further identify Tle1, a toxin effector encoded by this cluster and showed that Tle1 possesses phospholipase A1 and A2 activities required for the interbacterial competition. Self-protection of the attacker cell is secured by an outer membrane lipoprotein, Tli1, which binds Tle1 in a 1:1 stoichiometric ratio with nanomolar affinity, and inhibits its phospholipase activity. Tle1 is delivered into the periplasm of the prey cells using the VgrG1 needle spike protein as carrier. Further analyses demonstrate that the C-terminal extension domain of VgrG1, including a transthyretin-like domain, is responsible for the interaction with Tle1 and its subsequent delivery into target cells. Based on these results, we propose an additional mechanism of transport of T6SS effectors in which cognate effectors are selected by specific motifs located at the C-terminus of VgrG proteins. PMID:26714038

  12. Roles of Hcp family proteins in the pathogenesis of the porcine extraintestinal pathogenic Escherichia coli type VI secretion system

    PubMed Central

    Peng, Ying; Wang, Xiangru; Shou, Jin; Zong, Bingbing; Zhang, Yanyan; Tan, Jia; Chen, Jing; Hu, Linlin; Zhu, Yongwei; Chen, Huanchun; Tan, Chen

    2016-01-01

    Hcp (hemolysin-coregulated protein) is considered a vital component of the functional T6SS (Type VI Secretion System), which is a newly discovered secretion system. Our laboratory has previously sequenced the whole genome of porcine extraintestinal pathogenic E. coli (ExPEC) strain PCN033, and identified an integrated T6SS encoding three different hcp family genes. In this study, we first identified a functional T6SS in porcine ExPEC strain PCN033, and demonstrated that the Hcp family proteins were involved in bacterial competition and the interactions with other cells. Interestingly, the three Hcp proteins had different functions. Hcp2 functioned predominantly in bacterial competition; all three proteins were involved in the colonization of mice; and Hcp1 and Hcp3 were predominantly contributed to bacterial-eukaryotic cell interactions. We showed an active T6SS in porcine ExPEC strain PCN033, and the Hcp family proteins had different functions in their interaction with other bacteria or host cells. PMID:27229766

  13. Galvanic Corrosion In (Graphite/Epoxy)/Alloy Couples

    NASA Technical Reports Server (NTRS)

    Danford, Merlin D.; Higgins, Ralph H.

    1988-01-01

    Effects of galvanic coupling between graphite/epoxy composite material, G/E, and D6AC steel, 6061-T6 aluminum, and Inconel(R) 718 nickel alloy in salt water described in report. Introductory section summarizes previous corrosion studies of G/E with other alloys. Details of sample preparation presented along with photographs of samples before and after immersion.

  14. Predicted geographic ranges for North American sylvatic Trichinella

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of a lack of comprehensive surveys, the geographic distributions of the North American species of Trichinella (T. nativa and its variant T6, T. murrelli, and T. spiralis) are poorly characterized. These species are potentially zoonotic, and biogeographical information is critical to monitori...

  15. Structure of Saccharomyces cerevisiae mitochondrial Qri7 in complex with AMP

    PubMed Central

    Tominaga, Takumi; Kobayashi, Kan; Ishii, Ryohei; Ishitani, Ryuichiro; Nureki, Osamu

    2014-01-01

    N 6-Threonylcarbamoyladenosine (t6A) is a modified tRNA base required for accuracy in translation. Qri7 is localized in yeast mitochondria and is involved in t6A biosynthesis. In t6A biosynthesis, threonylcarbamoyl-adenylate (TCA) is synthesized from threonine, bicarbonate and ATP, and the threonyl-carbamoyl group is transferred to adenine 37 of tRNA by Qri7. Qri7 alone is sufficient to catalyze the second step of the reaction, whereas the Qri7 homologues YgjD (in bacteria) and Kae1 (in archaea and eukaryotes) function as parts of multi-protein complexes. In this study, the crystal structure of Qri7 complexed with AMP (a part of TCA) has been determined at 2.94 Å resolution in a new crystal form. The manner of AMP recognition is similar, with some minor variations, among the Qri7/Kae1/YgjD family proteins. The previously reported dimer formation was also observed in this new crystal form. Furthermore, a comparison with the structure of TobZ, which catalyzes a similar reaction to t6A biosynthesis, revealed the presence of a flexible loop that may be involved in tRNA binding. PMID:25084372

  16. Silencing trehalose-6-phosphate synthase incapacitates adult mosquitoes by interfering with the biosynthetic pathway for flight fuel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Trehalose is a disaccharide comprised of two glucose molecules. It is the main blood sugar of insects and is essential for flight. Trehalose is synthesized by two enzymes: trehalose-6-phosphate synthase (T6PS) converts glucose-6-phosphate to trehalose-6-phosphate, and trehalose-6-phosphate phosphata...

  17. Standardized Curriculum for Graphic and Print Communications.

    ERIC Educational Resources Information Center

    Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.

    Standardized vocational education course titles and core contents for two courses in Mississippi are provided: graphic and print communications I and II. The first course contains the following units: (1) orientation; (2) keyboard composer model 48 T 6; (3) keyboard composer model 7300; (4) job planning, art work, and layout; (5) basic…

  18. WARM AND FUZZY: TEMPERATURE AND DENSITY ANALYSIS OF AN Fe XV EUV IMAGING SPECTROMETER LOOP

    SciTech Connect

    Schmelz, J. T.; Rightmire, L. A.; Kimble, J. A.; Worley, B. T.; Pathak, S.; Saar, S. H.

    2011-09-10

    The Hinode EUV Imaging Spectrometer (EIS) and X-Ray Telescope (XRT) were designed in part to work together. They have the same spatial resolution and cover different but overlapping coronal temperature ranges. These properties make a combined data set ideal for multithermal analysis, where EIS provides the best information on the cooler corona (log T < 6.5) and XRT provides the best information on the hotter corona (log T > 6.5). Here, we analyze a warm non-flaring loop detected in images made in a strong EIS Fe XV emission line with a wavelength of 284.16 A and peak formation temperature of log T = 6.3. We perform differential emission measure (DEM) analysis in three pixels at different heights above the footpoint and find multithermal results with the bulk of the emission measure in the range 6.0 < log T < 6.6. Analysis with the EIS lines alone gave a DEM with huge amounts of emission measure at very high temperatures (log T >7.2); analysis with XRT data alone resulted in a DEM that was missing most of the cooler emission measure required to produce many of the EIS lines. Thus, both results were misleading and unphysical. It was only by combining the EIS and XRT data that we were able to produce a reasonable result, one without ad hoc assumptions on the shape and range of the DEM itself.

  19. High emittance surfaces for high temperature space radiator applications

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Hotes, Deborah

    1990-01-01

    Surface modification techniques are evaluated for emittance enhancement of radiator surfaces. These techniques include acid etching, heat treating, abrasion, sputter texturing, electrochemical texturing, arc texturing, and atomic oxygen beam texturing. Candidate radiator surface materials under consideration include Nb-1 pct Zr, Cu, Ti, Ti-6 pct Al-4 pct V, 304 stainless steel, Al6061-T6, Mo, W, and Ta.

  20. Start codon targeted (SCoT) polymorphism in toxic and non-toxic accessions of Jatropha curcas L. and development of a codominant SCAR marker.

    PubMed

    Mulpuri, Sujatha; Muddanuru, Tarakeswari; Francis, George

    2013-06-01

    Thirty six start codon targeted (SCoT) primers were used for characterization of 48 accessions of Jatropha curcas from different countries and include material with genetic variation for levels of phorbol esters, yield, seed oil content, test weight and plant type. SCoT analysis revealed high polymorphism and 74% of the primers generated polymorphic profiles. The SCoT6 primer discriminated edible and toxic accessions in a single reaction while the SCoT26 and 27 primers produced amplicons specific to toxic and non-toxic accessions, respectively. The polymorphic SCoT markers obtained with these three primers were converted to sequence characterized amplicon regions (SCARs) which resulted in codominant SCARs with SCoT6 primer and dominant SCARs with SCoT 26 and 27 primers. The codominant nature of SCoT6 primer and the resultant SCAR6 primer were validated on intraspecific hybrids derived from a cross between non-toxic and toxic accessions. The accession JP38 from Madagascar was found to be distinct and showed accession specific bands with 9 different SCoT primers. Sequence analysis of polymorphic amplicons obtained with SCoT6 primer showed a 65 bp deletion in accessions with low/zero phorbol esters. Diversity analysis separated the toxic and non-toxic accessions into two groups and the accessions JP29 and JP48 from Mexico formed a third cluster. PMID:23602106

  1. Dioxygenases Catalyze O-Demethylation and O,O-Demethylenation with Widespread Roles in Benzylisoquinoline Alkaloid Metabolism in Opium Poppy*

    PubMed Central

    Farrow, Scott C.; Facchini, Peter J.

    2013-01-01

    In opium poppy, the antepenultimate and final steps in morphine biosynthesis are catalyzed by the 2-oxoglutarate/Fe(II)-dependent dioxygenases, thebaine 6-O-demethylase (T6ODM) and codeine O-demethylase (CODM). Further investigation into the biochemical functions of CODM and T6ODM revealed extensive and unexpected roles for such enzymes in the metabolism of protopine, benzo[c]phenanthridine, and rhoeadine alkaloids. When assayed with a wide range of benzylisoquinoline alkaloids, CODM, T6ODM, and the functionally unassigned paralog DIOX2, renamed protopine O-dealkylase, showed novel and efficient dealkylation activities, including regio- and substrate-specific O-demethylation and O,O-demethylenation. Enzymes catalyzing O,O-demethylenation, which cleave a methylenedioxy bridge leaving two hydroxyl groups, have previously not been reported in plants. Similar cleavage of methylenedioxy bridges on substituted amphetamines is catalyzed by heme-dependent cytochromes P450 in mammals. Preferred substrates for O,O-demethylenation by CODM and protopine O-dealkylase were protopine alkaloids that serve as intermediates in the biosynthesis of benzo[c]phenanthridine and rhoeadine derivatives. Virus-induced gene silencing used to suppress the abundance of CODM and/or T6ODM transcripts indicated a direct physiological role for these enzymes in the metabolism of protopine alkaloids, and they revealed their indirect involvement in the formation of the antimicrobial benzo[c]phenanthridine sanguinarine and certain rhoeadine alkaloids in opium poppy. PMID:23928311

  2. Trehalose-6-Phosphate Phosphatase is required for cell wall integrity and fungal virulence but not trehalose biosynthesis in the human fungal pathogen Aspergillus fumigatus

    PubMed Central

    Puttikamonkul, Srisombat; Willger, Sven D.; Grahl, Nora; Perfect, John R.; Movahed, Navid; Bothner, Brian; Park, Steven; Paderu, Padmaja; Perlin, David S.; Cramer, Robert A.

    2010-01-01

    Summary The trehalose biosynthesis pathway is critical for virulence in human and plant fungal pathogens. In this study, we tested the hypothesis that trehalose-6-phosphate phosphatase (T6PP) is required for Aspergillus fumigatus virulence. A mutant of the A. fumigatus T6PP, OrlA, displayed severe morphological defects related to asexual reproduction when grown on glucose (1%) minimal media. These defects could be rescued by addition of osmotic stabilizers, reduction in incubation temperature, or increase in glucose levels (>4%). Subsequent examination of the mutant with cell wall perturbing agents revealed a link between cell wall biosynthesis and trehalose-6-phosphate (T6P) levels. As expected, high levels of T6P accumulated in the absence of OrlA resulting in depletion of free inorganic phosphate (Pi) and inhibition of hexokinase activity. Surprisingly, trehalose production persisted in the absence of OrlA. Further analyses revealed that A. fumigatus contains two trehalose phosphorylases that may be responsible for trehalose production in the absence of OrlA. Despite a normal growth rate under in vitro growth conditions, the orlA mutant was virtually avirulent in two distinct murine models of invasive pulmonary aspergillosis. Our results suggest that further study of this pathway will lead to new insights into regulation of fungal cell wall biosynthesis and virulence. PMID:20545865

  3. TssK Is a Trimeric Cytoplasmic Protein Interacting with Components of Both Phage-like and Membrane Anchoring Complexes of the Type VI Secretion System*

    PubMed Central

    Zoued, Abdelrahim; Durand, Eric; Bebeacua, Cecilia; Brunet, Yannick R.; Douzi, Badreddine; Cambillau, Christian; Cascales, Eric; Journet, Laure

    2013-01-01

    The Type VI secretion system (T6SS) is a macromolecular machine that mediates bacteria-host or bacteria-bacteria interactions. The T6SS core apparatus assembles from 13 proteins that form two sub-assemblies: a phage-like complex and a trans-envelope complex. The Hcp, VgrG, TssE, and TssB/C subunits are structurally and functionally related to components of the tail of contractile bacteriophages. This phage-like structure is thought to be anchored to the membrane by a trans-envelope complex composed of the TssJ, TssL, and TssM proteins. However, how the two sub-complexes are connected remains unknown. Here we identify TssK, a protein that establishes contacts with the two T6SS sub-complexes through direct interactions with TssL, Hcp, and TssC. TssK is a cytoplasmic protein assembling trimers that display a three-armed shape, as revealed by TEM and SAXS analyses. Fluorescence microscopy experiments further demonstrate the requirement of TssK for sheath assembly. Our results suggest a central role for TssK by linking both complexes during T6SS assembly. PMID:23921384

  4. Localized pruritus-notalgia paresthetica.

    PubMed

    Massey, E W; Pleet, A B

    1979-08-01

    Notalgia paresthetica, possibly an isolated sensory neuropathy involving the posterior primary rami of thoracic nerves T2 through T6, and appearing as pruritus of the back, is apt to be encountered by both dermatologists and neurologists. Two cases illustrate this disorder. PMID:464629

  5. Notalgia paresthetica owing to compression neuropathy: case presentation including electrodiagnostic studies.

    PubMed

    Streib, E W; Sun, S F

    1981-01-01

    A patient developed numbness over the upper part of his back, following prolonged bed rest in a supine position. Sweat test, clinical and electromyographic examination indicated neuropathies of the primary dorsal rami of the spinal nerves from T2 to T6. The literature is reviewed and anatomical considerations discussed. PMID:7202444

  6. Mutation in the S-ribosylhomocysteinase (luxS) gene involved in quorum sensing affects biofilm formation and virulence in a clinical isolate of Aeromonas hydrophila

    EPA Science Inventory

    A diarrheal isolate SSU of Aeromonas hydrophila produces a cytotoxic enterotoxin (Act) with cytotoxic, enterotoxic, and hemolytic activities. Our laboratory has characterized from the above Aeromonas strain, in addition to Act, the type 3- and T6-secretion systems and their effec...

  7. 76 FR 47522 - Airworthiness Directives; The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-05

    .... Discussion On June 5, 1995, we issued AD 95-12-17, amendment 39-9268 (60 FR 36981, July 19, 1995), for... produced with outboard chords at BS 727 made of 7075-T6 aluminum; subsequent airplanes were produced with outboard chords made of 7075-T73 aluminum. In addition, we have determined that the inspections of...

  8. Improved thermal treatment of aluminum alloy 7075

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.

    1968-01-01

    Newly developed tempering treatment considerably increases the corrosion resistance of 7075-T6 alloy and concomitantly preserves its yield strength. The results of tests on samples of the alloy subjected to the above treatments show that when the overaging period is 12 hours /at 325 degrees F/, the alloy exhibits a yield strength of 73,000 psi.

  9. 77 FR 32918 - Airworthiness Directives; The Boeing Company Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), (3) Will... identified 7075-T6 alloy, instead of the required 2024-T3 clad material. The airplane had accumulated... paragraph (i)(1) of this AD. Confirming the upper butt strap is made from 2000 series aluminum...

  10. 27 CFR 9.195 - Alta Mesa.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... County, California, and is entirely within the Lodi viticultural area (27 CFR 9.107). The Alta Mesa... line's intersection with the 105-foot contour line and an unimproved extension of Blake Road, section 9, T6N, R7E (Sloughhouse Quadrangle); then (9) Proceed west 0.3 mile on the unimproved extension of...

  11. 27 CFR 9.195 - Alta Mesa.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... County, California, and is entirely within the Lodi viticultural area (27 CFR 9.107). The Alta Mesa... line's intersection with the 105-foot contour line and an unimproved extension of Blake Road, section 9, T6N, R7E (Sloughhouse Quadrangle); then (9) Proceed west 0.3 mile on the unimproved extension of...

  12. 27 CFR 9.195 - Alta Mesa.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... County, California, and is entirely within the Lodi viticultural area (27 CFR 9.107). The Alta Mesa... line's intersection with the 105-foot contour line and an unimproved extension of Blake Road, section 9, T6N, R7E (Sloughhouse Quadrangle); then (9) Proceed west 0.3 mile on the unimproved extension of...

  13. Regulation of Type VI Secretion Gene Clusters by σ54 and Cognate Enhancer Binding Proteins▿†

    PubMed Central

    Bernard, Christophe S.; Brunet, Yannick R.; Gavioli, Marthe; Lloubès, Roland; Cascales, Eric

    2011-01-01

    Type VI secretion systems (T6SS) are bacteriophage-derived macromolecular machines responsible for the release of at least two proteins in the milieu, which are thought to form an extracellular appendage. Although several T6SS have been shown to be involved in the virulence of animal and plant pathogens, clusters encoding these machines are found in the genomes of most species of Gram-negative bacteria, including soil, marine, and environmental isolates. T6SS have been associated with several phenotypes, ranging from virulence to biofilm formation or stress sensing. Their various environmental niches and large diversity of functions are correlated with their broad variety of regulatory mechanisms. Using a bioinformatic approach, we identified several clusters, including those of Vibrio cholerae, Aeromonas hydrophila, Pectobacterium atrosepticum, Pseudomonas aeruginosa, Pseudomonas syringae pv. tomato, and a Marinomonas sp., which possess typical −24/−12 sequences, recognized by the alternate sigma factor sigma 54 (σ54 or σN). σ54, which directs the RNA polymerase to these promoters, requires the action of a bacterial enhancer binding protein (bEBP), which binds to cis-acting upstream activating sequences. Putative bEBPs are encoded within the T6SS gene clusters possessing σ54 boxes. Using in vitro binding experiments and in vivo reporter fusion assays, we showed that the expression of these clusters is dependent on both σ54 and bEBPs. PMID:21378190

  14. Plumbagin Ameliorates CCl4-Induced Hepatic Fibrosis in Rats via the Epidermal Growth Factor Receptor Signaling Pathway

    PubMed Central

    Chen, Si; Chen, Yi; Chen, Bi; Cai, Yi-jing; Zou, Zhuo-lin; Wang, Jin-guo; Lin, Zhuo; Wang, Xiao-dong; Fu, Li-yun; Hu, Yao-ren; Chen, Yong-ping; Chen, Da-zhi

    2015-01-01

    Epidermal growth factor (EGF) and its signaling molecules, EGFreceptor (EGFR) and signal transducer and activator of transcription factor 3 (STAT3), have been considered to play a role in liver fibrosis and cirrhosis. Plumbagin (PL) is an extracted component from the plant and has been used to treat different kinds of cancer. However, its role in regulation of EGFR and STAT3 during liver fibrosis has not been investigated. In this study, the effects of PL on the regulation of EGFR and STAT3 were investigated in carbon tetrachloride (CCl4) induced liver fibrosis and hepatic stellate cells (HSC-T6). PL significantly attenuated liver injury and fibrosis in CCl4 treated rats. At concentrations of 2 to 6 μM, PL did not induce significant cytotoxicity of HSC-T6 cells. Moreover, PL reduced phosphorylation of EGFR and STAT3 in both fibrotic liver and heparin-binding EGF-like growth factor (HB-EGF) treated HSC-T6 cells. Furthermore, PL reduced the expression of α-SMA, EGFR, and STAT3 in both fibrotic liver and HB-EGF treated HSC-T6 cells. In conclusion, plumbagin could ameliorate the development of hepatic fibrosis through its downregulation of EGFR and STAT3 in the liver, especially in hepatic stellate cells. PMID:26550019

  15. Influence of hot isostatic pressing on the structure and properties of an innovative low-alloy high-strength aluminum cast alloy based on the Al-Zn-Mg-Cu-Ni-Fe system

    NASA Astrophysics Data System (ADS)

    Akopyan, T. K.; Padalko, A. G.; Belov, N. A.

    2015-11-01

    Hot isostatic pressing (HIP) is applied for treatment of castings of innovative low-ally high-strength aluminum alloy, nikalin ATs6N0.5Zh based on the Al-Zn-Mg-Cu-Ni-Fe system. The influence of HIP on the structure and properties of castings is studied by means of three regimes of barometric treatment with different temperatures of isometric holding: t 1 = 505 ± 2°C, p 1 = 100 MPa, τ1 = 3 h (HIP1); t 2 = 525 ± 2°C, p 2 = 100 MPa, τ2 = 3 h (HIP2); and t 3 = 545 ± 2°C, p 3 = 100 MPa, τ3 = 3 h (HIP3). It is established that high-temperature HIP leads to actually complete elimination of porosity and additional improvement of the morphology of second phases. Improved structure after HIP provides improvement properties, especially of plasticity. In particular, after heat treatment according of regime HIP2 + T4 (T4 is natural aging), the alloy plasticity is improved by about two times in comparison with the initial state (from ~6 to 12%). While applying regime HIP3 + T6 (T6 is artificial aging for reaching the maximum strength), the plasticity has improved by more than three times in comparison with the initial state, as after treatment according to regimes HIP1 + T6 and HIP2 + T6 (from ~1.2 to ~5.0%), which are characterized by a lower HIP temperature.

  16. Depressive Symptoms and Associated Psychosocial Factors among Adolescent Survivors 30 Months after 2008 Wenchuan Earthquake: A Follow-Up Study

    PubMed Central

    Shi, Xuliang; Yu, Nancy X.; Zhou, Ya; Geng, Fulei; Fan, Fang

    2016-01-01

    Purpose: This study longitudinally investigated the changes of depressive symptoms among adolescent survivors over 2 years and a half after the 2008 Wenchuan earthquake in China, as well as the predictive effects of demographic characteristics, earthquake exposure, negative life events, social support, and dispositional resilience on the risk of depressive symptoms at two time points after the earthquake. Methods: Participants were 1573 adolescent survivors (720 males and 853 females, mean age at initial survey = 15.00 ± 1.26 years), whose depressive symptoms were assessed at 6 months (T6m) and 30 months (T30m) post-earthquake. Data on demographics, earthquake exposure, and dispositional resilience were collected at T6m. Negative life events and social support were measured at T6m and 24 months (T24m) post-earthquake. Results: The prevalence rates of probable depression, 27.5 at T6m and 27.2% at T30m, maintained relatively stable over time. Female gender was related with higher risk of depressive symptoms at both T6m and T30m, while being only child could only predict higher risk of depressive symptoms at T30m. Negative life events and social support at T6m, as well as earthquake exposure, were concurrently associated with increased risk of depressive symptoms at T6m, but not associated with the risk of depressive symptoms at T30m, while negative life events and social support at T24m could predict depressive symptoms at T30m, all of which suggested that these variables may have strong but short-term effect on adolescents’ depressive symptoms post-earthquake. Besides, dispositional resilience was evidenced as a relatively stable negative predictor for depressive symptoms. Conclusions: These findings could inform mental health professionals regarding how to screen adolescent survivors at high risk for depression, so as to provide them with timely and appropriate mental health services based on the identified risk and protective factors for depressive symptoms

  17. Changes in blood testosterone concentrations after surgical and chemical sterilization of male free-roaming dogs in southern Chile.

    PubMed

    Vanderstichel, R; Forzán, M J; Pérez, G E; Serpell, J A; Garde, E

    2015-04-01

    There is a growing interest in chemical sterilization as an alternative to surgical castration in large-scale sterilization campaigns to control canine populations. An important step toward understanding the short-term and long-term effects of chemical sterilants is to determine their impact on blood testosterone concentrations, particularly as these could influence dog behavior after treatment. A field trial was conducted with 118 free-roaming male dogs in the Chilean Patagonia, where 36 dogs were chemically sterilized using EsterilSol, 39 dogs were surgically castrated, and 43 dogs remained intact as controls. Blood testosterone levels were determined at four time periods: on enrollment 6 months before treatment (t-6m), at the time of treatment (t0, within one hour after surgical castration or chemical sterilization and during a concurrent 2-week period for the control group), four (t+4m), and six (t+6m) months after treatment. Intrinsic and temporal factors were evaluated; age was significantly associated with testosterone, where dogs 2- to 4-year-old had the highest testosterone concentrations (P = 0.036), whereas body weight and body condition scores were not associated with testosterone; testosterone concentration was not influenced by time of day, month, or season. After treatment (t+4m and t+6m), all of the surgically castrated dogs had testosterone concentrations below 1.0 ng/mL. On the basis of this cut point (<1 ng/mL), testosterone remained unchanged in 66% of the chemically sterilized dogs at both t+4m and t+6m; it remained low for 22% of dogs at both t+4m and t+6m; it was unchanged at t+4m but low at t+6m in 9% of dogs; and, it was low at t+4m but reverted back to unchanged at t+6m in one dog (3%). Incidentally, testosterone in chemically sterilized dogs increased dramatically within 1 hour of treatment (t0), more than doubling (131%) the concentration of control dogs at the time of treatment (t0), likely because of severe necrosis of

  18. Effects of black pepper (piper nigrum), turmeric powder (curcuma longa) and coriander seeds (coriandrum sativum) and their combinations as feed additives on growth performance, carcass traits, some blood parameters and humoral immune response of broiler chickens.

    PubMed

    Abou-Elkhair, R; Ahmed, H A; Selim, S

    2014-06-01

    Different herbs and spices have been used as feed additives for various purposes in poultry production. This study was conducted to assess the effect of feed supplemented with black pepper (Piper nigrum), turmeric powder (Curcuma longa), coriander seeds (Coriandrum sativum) and their combinations on the performance of broilers. A total of 210 (Cobb) one-d-old chicks were divided into seven groups of 30 birds each. The treatments were: a control group received no supplement, 0.5% black pepper (T1), 0.5% turmeric powder (T2), 2% coriander seeds (T3), a mixture of 0.5% black pepper and 0.5% turmeric powder (T4), a mixture of 0.5% black pepper and 2% coriander seed (T5), and a mixture of 0.5% black pepper, 0.5% turmeric powder and 2% coriander seeds (T6). Higher significant values of body weight gain during the whole period of 5 weeks (p<0.001) were observed in broilers on T1, T3, T5, and T6 compared to control. Dietary supplements with T1, T2, T3, and T6 improved the cumulative G:F of broilers during the whole period of 5 weeks (p<0.001) compared with control. The dressing percentage and edible giblets were not influenced by dietary supplements, while higher values of relative weight of the liver (p<0.05) were obtained in T5 and T6 compared to control. The addition of feed supplements in T5 and T6 significantly increased serum total protein and decreased serum glucose, triglycerides and alkaline phosphatase concentrations compared with the control group (p<0.05). Broilers on T6 showed significant decrease in the serum glutamate pyruvate transaminase concentration (p<0.05) compared to control. The broilers having T5 and T6 supplemented feed had relatively greater antibody titre (p<0.001) at 35 d of age than control. It is concluded that dietary supplements with black pepper or coriander seeds or their combinations enhanced the performance and health status of broiler chickens. PMID:25050023

  19. Coevolution of the ATPase ClpV, the Sheath Proteins TssB and TssC, and the Accessory Protein TagJ/HsiE1 Distinguishes Type VI Secretion Classes*

    PubMed Central

    Förster, Andreas; Planamente, Sara; Manoli, Eleni; Lossi, Nadine S.; Freemont, Paul S.; Filloux, Alain

    2014-01-01

    The type VI secretion system (T6SS) is a bacterial nanomachine for the transport of effector molecules into prokaryotic and eukaryotic cells. It involves the assembly of a tubular structure composed of TssB and TssC that is similar to the tail sheath of bacteriophages. The sheath contracts to provide the energy needed for effector delivery. The AAA+ ATPase ClpV disassembles the contracted sheath, which resets the systems for reassembly of an extended sheath that is ready to fire again. This mechanism is crucial for T6SS function. In Vibrio cholerae, ClpV binds the N terminus of TssC within a hydrophobic groove. In this study, we resolved the crystal structure of the N-terminal domain of Pseudomonas aeruginosa ClpV1 and observed structural alterations in the hydrophobic groove. The modification in the ClpV1 groove is matched by a change in the N terminus of TssC, suggesting the existence of distinct T6SS classes. An accessory T6SS component, TagJ/HsiE, exists predominantly in one of the classes. Using bacterial two-hybrid approaches, we showed that the P. aeruginosa homolog HsiE1 interacts strongly with ClpV1. We then resolved the crystal structure of HsiE1 in complex with the N terminus of HsiB1, a TssB homolog and component of the contractile sheath. Phylogenetic analysis confirmed that these differences distinguish T6SS classes that resulted from a functional co-evolution between TssB, TssC, TagJ/HsiE, and ClpV. The interaction of TagJ/HsiE with the sheath as well as with ClpV suggests an alternative mode of disassembly in which HsiE recruits the ATPase to the sheath. PMID:25305017

  20. A longitudinal study of streptococcus pneumoniae carriage in healthy children in the 13-valent pneumococcal conjugate vaccine era

    PubMed Central

    Mameli, Chiara; Fabiano, Valentina; Daprai, Laura; Bedogni, Giorgio; Faccini, Marino; Garlaschi, Maria Laura; Penagini, Francesca; Dilillo, Dario; Torresani, Erminio; Gramegna, Maria; Zuccotti, Gian Vincenzo

    2015-01-01

    Few epidemiological data are available after the introduction of the 13-valent pneumococcal vaccine (PCV13) in 2010. We performed repeat nasopharyngeal swabs and evaluated the serotype distribution of Streptococcus pneumoniae (SP) and its association with PCV13 vaccine status in healthy Italian children aged 3–59 months. SP serotypes were assessed by the Quellung reaction. 618 children appropriately (28%) or incompletely (72%) vaccinated for age with PCV13 were available at baseline (T0). 515 were re-evaluated at 6 months from baseline (T6) and 436 at 12 months from baseline (T12). The percentage of appropriately vaccinated subjects at T0, T6 and T12 was 28%, 67% and 92%, respectively. Random effects logistic regression models with robust 95% confidence intervals was used to estimate the time-related changes in SP and PCV13 carriage and marginal probabilities were obtained from such models. The age-corrected probability of SP carriage was 0.31 (95% CI 0.22 - 0.41) at T0, 0.32 (0.24 - 0.40) at T6 and 0.28 (0.20 - 0.35) at T12. The probability of PCV13 serotypes carriage was 0.025 (0.001 - 0.050) at T0, 0.018 (0.001 - 0.039) at T6 and 0.010 (0.001 - 0.023) at T12. A decrease in PCV13 serotypes and a shift in non-PCV13 serotypes colonization was observed. In particular, the 15A serotype accounted for 4%, 8% and 23% of SP isolates at T0, T6 and T12, respectively. In conclusion, the benefits of the PCV13 vaccination on SP carriage increase with increasing coverage rates. The shift of SP isolates toward non-PCV13 serotypes needs to be studied further. PMID:25751237

  1. The rise of the Type VI secretion system

    PubMed Central

    2013-01-01

    Bacterial cells have developed multiple strategies to communicate with their surrounding environment. The intracellular compartment is separated from the milieu by a relatively impermeable cell envelope through which small molecules can passively diffuse, while larger macromolecules, such as proteins, can be actively transported. In Gram-negative bacteria, the cell envelope is a double membrane, which houses several supramolecular protein complexes that facilitate the trafficking of molecules. For example, bacterial pathogens use these types of machines to deliver toxins into target eukaryotic host cells, thus subverting host cellular functions. Six different types of nanomachines, called Type I - Type VI secretion systems (T1SS - T6SS), can be readily identified by their composition and mode of action. A remarkable feature of these protein secretion systems is their similarity to systems with other biological functions, such as motility or the exchange of genetic material. The T6SS has provided a refreshing view on this concept since it shares similarity with the puncturing device of bacteriophages, which is used by these viruses to inject their DNA into bacterial target cells. In contrast, the bacterial T6SS transports toxins into other bacteria, engaging a ferocious competition for the colonization of their environment. Moreover, as with few other secretion systems, the T6SS is capable of injecting toxins into eukaryotic cells, which contributes to a successful infection. This highlights the multifunctional aspects of the T6SS, and our understanding of its mechanistic details is an intense field of investigation with significant implications for ecology, agriculture and medicine. PMID:24381728

  2. Factors that influence healing of chronic venous leg ulcers: a retrospective cohort*

    PubMed Central

    Scotton, Marilia Formentini; Miot, Hélio Amante; Abbade, Luciana Patricia Fernandes

    2014-01-01

    BACKGROUND Venous ulcers have a significant impact on patient quality of life, and constitute a worldwide public health problem. Treatment is complex, with high failure rates. OBJECTIVES To identify clinical and therapeutic factors that influence healing of venous ulcers. METHODS Retrospective cohort study of patients with venous ulcers. Ulcer area was measured at the first visit (T0) and after 6 months (T6) and 1 year (T12). A reduction in ulcer area of 50% or more at T6 and T12 was the outcome of interest, weighted by clinical, demographic and treatment aspects. RESULTS Ninety-four patients were included (137 ulcers). A reduction in ulcer area of 50% or more was seen in 40.1% of patients (95%CI 31.9 to 48.4%) at T6 and 49.6% (95%CI 41.2 to 58.1%) at T12. Complete healing occurred in 16.8% (95%CI 10.5 to 23.1%) at T6 and 27% (95%CI 19.5 to 39.5%) at T12. The lowest ulcer area reductions at T6 were associated with longstanding ulcer (RR=0.95; 95%CI 0.91 to 0.98), poor adherence to compression therapy (RR=4.04; 95%CI 1.31 to 12.41), and infection episodes (RR= 0.42; 95%CI 0.23 to 0.76). At T12, lower reductions were associated with longstanding ulcer (RR=0.95; 95%CI 0.92 to 0.98), longer topical antibiotic use (RR=0.93; 95%CI 0.87 to 0.99), and systemic antibiotic use (RR=0.63; 95%CI 0.40 to 0.99). CONCLUSIONS Longstanding ulcer, infection, poor adherence to compression therapy, and longer topical and systemic antibiotic use were independently correlated with worse healing rates. PMID:24937814

  3. Secretome Analysis of Vibrio cholerae Type VI Secretion System Reveals a New Effector-Immunity Pair

    PubMed Central

    Altindis, Emrah; Dong, Tao; Catalano, Christy

    2015-01-01

    ABSTRACT The type VI secretion system (T6SS) is a dynamic macromolecular organelle that many Gram-negative bacteria use to inhibit or kill other prokaryotic or eukaryotic cells. The toxic effectors of T6SS are delivered to the prey cells in a contact-dependent manner. In Vibrio cholerae, the etiologic agent of cholera, T6SS is active during intestinal infection. Here, we describe the use of comparative proteomics coupled with bioinformatics to identify a new T6SS effector-immunity pair. This analysis was able to identify all previously identified secreted substrates of T6SS except PAAR (proline, alanine, alanine, arginine) motif-containing proteins. Additionally, this approach led to the identification of a new secreted protein encoded by VCA0285 (TseH) that carries a predicted hydrolase domain. We confirmed that TseH is toxic when expressed in the periplasm of Escherichia coli and V. cholerae cells. The toxicity observed in V. cholerae was suppressed by coexpression of the protein encoded by VCA0286 (TsiH), indicating that this protein is the cognate immunity protein of TseH. Furthermore, exogenous addition of purified recombinant TseH to permeabilized E. coli cells caused cell lysis. Bioinformatics analysis of the TseH protein sequence suggest that it is a member of a new family of cell wall-degrading enzymes that include proteins belonging to the YD repeat and Rhs superfamilies and that orthologs of TseH are likely expressed by species belonging to phyla as diverse as Bacteroidetes and Proteobacteria. PMID:25759499

  4. Impact Welding of Aluminum to Copper and Stainless Steel by Vaporizing Foil Actuator: Effect of Heat Treatment Cycles on Mechanical Properties and Microstructure

    NASA Astrophysics Data System (ADS)

    Vivek, Anupam; Hansen, Steven; Benzing, Jake; He, Mei; Daehn, Glenn

    2015-10-01

    This work studies the mechanical property effect of microstructure on impact welds of aluminum alloy AA6061 with both copper alloy Cu 110 and stainless steel AISI 304. AA6061-T6 and T4 temper aluminum sheets of 1 mm thickness were launched toward copper and stainless steel targets using the vaporizing foil actuator technique. Flyer plate velocities, measured via photonic Doppler velocimetry, were observed to be approximately 800 m/s. The welded aluminum-copper samples were subjected to instrumented peel testing, microhardness testing, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The welded joints exhibited cracks through their continuous intermetallic layers. The cracks were impeded upon encountering a ductile metallic wave. The welds created with T6 temper flyer sheets were found to have smaller intermetallic-free and wavy interface regions as compared to those created with T4 temper flyer sheets. Peel strength tests of the two weld combinations resulted in failure along the interface in the case of the T6 flyer welds, while the failure generally occurred in the parent aluminum for the T4 temper flyer welds. Half of the T4 flyer welds were subjected to aging for 18 h at 433 K (160 °C) to convert the aluminum sheet to the T6 condition. Although the aged flyer material did not attain the hardness of the as-received T6 material, it was found to be significantly stronger than the T4 material. These welds retained their strength after the aging process, and diffusion across the interface was minimal. The welded aluminum-stainless steel samples were analyzed on a more basic level than aluminum-copper samples, but were found to exhibit similar results.

  5. Effects of glycyrrhizin, an active component of licorice roots, on Candida albicans infection in thermally injured mice

    PubMed Central

    Utsunomiya, T; Kobayashi, M; Herndon, D N; Pollard, R B; Suzuki, F

    1999-01-01

    Due to the generation of burn-associated CD8+ CD11b+ TCR γ/δ+ type 2 T cells (burn-associated type 2 T cells), the susceptibility of thermally injured mice to infection with C. albicans has been shown to be increased by up to 50-fold when compared with normal mice. Glycyrrhizin (GR), an active component of licorice roots, reduced the susceptibility of thermally injured mice to C. albicans infection to levels observed in normal mice. Thermally injured mice inoculated with CD4+ T cells from GR-treated mice were also resistant to C. albicans infection. The following demonstrated that susceptibility to fungal infection was similar in thermally injured mice and normal mice inoculated with T6S cells (a clone of burn-associated type 2 T cells). This susceptibility of T6S mice (normal mice inoculated with T6S cells) was reversible by (i) administration of GR, (ii) inoculation of CD4+ T cells from GR-treated mice, and (iii) injection of a mixture of MoAbs targeted against type 2 cytokines (IL-4 and IL-10). After stimulation with anti-CD3 MoAb, splenic T cells from thermally injured and T6S mice, treated with GR or inoculated with CD4+ T cells from GR-treated mice, did not have type 2 cytokines in culture supernatants. They were present in splenic T cell cultures from thermally injured and T6S mice that were treated with saline or inoculated with naive T cells. These results suggest that GR, by inducing CD4+ T cells which suppress type 2 cytokines produced by burn-associated type 2 T cells, improves the resistance of thermally injured mice to C. albicans. An anti-type 2 T cell action of the CD4+ T cells derived from GR-treated mice was previously described. PMID:10337021

  6. Evaluation of 7XXX-series aluminum alloys for the W87 aft support ring

    SciTech Connect

    Mahin, K.W.

    1985-03-01

    The study showed that the tensile properties of both 7075-T6 and 7050-T73651 decreased significantly after holding the alloys for any length of time at temperatures greater than 500/sup 0/F. After a 2-min hold at 575/sup 0/F, the yield strengths of 7075-T6 and 7050-T73651 were 217 MPa (31.5 ksi) and 245 MPa (35.6 ksi), respectively. There did not appear to be a significant difference in the mechanical properties between 7075-T6 and 7050-T6. Time at temperature appeared to be a critical parameter. Cycling the microstructure to 575/sup 0/F or above with no hold at temperature caused considerably less degradation in mechanical properties than a 2-min hold at temperature in all cases. Above 650/sup 0/F, both the ultimate tensile strength and the yield strength of the alloys reached a minimum of around 310 MPa (45 ksi) and 138 MPa (20 ksi), respectively. Evidence of a continuous grain boundary film of eta phase precipitates was found in the 7075-T6 alloy after a typical 575/sup 0/F thermal cycle. The presence of this grain boundary precipitate indicated a potential sensitivity of this alloy to stress corrosion cracking. Although the general environment for the aft support ring is controlled, the ring is expected to be under tension after assembly and exposure to small amounts of water vapor will probably occur. The conditions of stress, moisture, and susceptible microstructure increase the likelihood of stress corrosion cracking.

  7. New approach for the strategic control of gastrointestinal nematodes in grazed beef cattle during the growing phase in central Brazil.

    PubMed

    Heckler, R P; Borges, D G L; Vieira, M C; Conde, M H; Green, M; Amorim, M L; Echeverria, J T; Oliveira, T L; Moro, E; Van Onselen, V J; Borges, F A

    2016-05-15

    We evaluated the effect of different treatment protocols against gastrointestinal nematodes in Nelore beef cattle during the growing phase in the municipality of Terenos, MS, in central Brazil from May 2013 to April 2014 and from May 2014 to April 2015. Ninety-six Nelore calves were kept on Brachiaria brizantha grass during each trial period and were distributed into six experimental groups (replicate paddocks for each group) based on live weight and the number of eggs per gram of feces (EPG): T1 (control)-treated in May, July and September with a saline solution; T2-treated in May and November with 700μg/kg doramectin; T3-treated in May (doramectin), July (4.7mg/kg levamisole phosphate) and September (doramectin); T4-treated in May (doramectin), July (200μg/kg moxidectin) and September (doramectin); T5-treated in May (doramectin), August (levamisole phosphate) and November (doramectin) and T6-treated in May (doramectin), August (moxidectin) and November (doramectin). The calves were weighed and feces were collected (for faecal culture and EPG counts) from calves every 28days, concomitantly with the collection of forage samples. The efficacies of doramectin, moxidectin and levamisole were low, at 69.2, 65.9 and 69.4% in the first and 13.8, 92.6, and 76.5% in the second experimental periods, respectively, but only the untreated animals lost weight during the dry season. Final weight gains did not differ significantly (p>0.05) among the animals in T2 (120.8kg), T3 (131.4kg), T4 (131.2kg) and T5 (134.4kg). T6 was the only group with a significantly higher final weight gain (140.9kg) compared to the protocol with two annual dosages (T2). The weight gain was 31.9% higher in T6 than in the untreated animals (T1). None of the protocols affected the number of larvae on the pasture. Body weight was significantly and negatively (r=-0.65) correlated with EPG counts, which were significantly lower in June (T2, T3, T4 and T6), August (T3), September (T5 and T6), October (T5

  8. Molecular Characterization of a Functional Type VI Secretion System from a Clinical Isolate of Aeromonas hydrophila

    PubMed Central

    Suarez, Giovanni; Sierra, Johanna C.; Sha, Jian; Wang, Shaofei; Erova, Tatiana E.; Fadl, Amin A.; Foltz, Sheri M.; Horneman, Amy J.; Chopra, Ashok K.

    2008-01-01

    Our laboratory recently molecularly characterized the type II secretion system (T2SS)- associated cytotoxic enterotoxin (Act) and the T3SS-secreted AexU effector from a diarrheal isolate SSU of Aeromonas hydrophila. The role of these toxin proteins in the pathogenesis of A. hydrophila infections was subsequently delineated in in vitro and in vivo models. In this study, we characterized the new type 6 secretion system (T6SS) from isolate SSU of A. hydrophila and demonstrated its role in bacterial virulence. Study of the role of T6SS in bacterial virulence is in its infancy, and there are, accordingly, only limited, recent reports directed toward a better understanding its role in bacterial pathogenesis. We have provided evidence that the virulence-associated secretion (vas) genes vasH (Sigma 54-dependent transcriptional regulator) and vasK (encoding protein of unknown function) are essential for expression of the genes encoding the T6SS and/or they constituted important components of the T6SS. Deletion of the vasH gene prevented expression of the potential translocon hemolysin coregulated protein (Hcp) encoding gene from bacteria, while the vasK gene deletion prevented secretion but not translocation of Hcp into host cells. The secretion of Hcp was independent of the T3SS and the flagellar system. We demonstrated that secreted Hcp could bind to the murine RAW 264.7 macrophages from outside, in addition to its ability to be translocated into host cells. Further, the vasH and vasK mutants were less toxic to murine macrophages and human epithelial HeLa cells, and these mutants were more efficiently phagocytosed by macrophages. We also provided evidence that the expression of the hcp gene in the HeLa cell resulted in apoptosis of the host cells. Finally, the vasH and vasK mutants of A. hydrophila were less virulent in a septicemic mouse model of infection, and animals immunized with recombinant Hcp were protected from subsequent challenge with the wild-type (WT

  9. Different pathways of radical translocation in yeast cytochrome c peroxidase and its W191F mutant on reaction with H(2)O(2) suggest an antioxidant role.

    PubMed

    Tsaprailis, George; English, Ann M

    2003-02-01

    In the absence of exogenous donors, turnover of 10 molar equivalents of H(2)O(2) by wild-type recombinant cytochrome c peroxidase [CCP(MI)] and its W191F mutant at pH 7.0 occurs by oxidation of endogenous donors on the polypeptide. No O(2) evolution was observed with either enzyme on reaction with 10 molar equivalents of H(2)O(2), eliminating catalase-like activity, but O(2) evolution was observed when 100 molar equivalents of H(2)O(2) were added to the enzymes. Protein dimers were observed by SDS-PAGE following H(2)O(2) turnover by the peroxidases, and dimeric forms of CCP(MI) and CCP(W191) were isolated by gel-permeation chromatography. LC-ESI-MS analysis of the tryptic digests of the dimers revealed the previously reported T(6)-T(6) crosslink and a new crosslink between T(6)-T(26), but no T(26)-T(26) crosslink. The crosslinked tryptic peptides contain the exposed tyrosine residues Tyr36, Tyr39 and Tyr42 (T(6)), and Tyr229 and Tyr236 (T(26)). Addition of a spin trap, 2-methyl-2-nitrosopropane (MNP), to the CCP(MI)/H(2)O(2) reaction resulted in MNP labeling of peptides T(6), T(21) (which contains Tyr153) and T(26). MNP labeling of Tyr236 was found by sequencing peptide T(26). MNP labeling did not compete with dimerization of H(2)O(2)-oxidized CCP(W191F), suggesting that dityrosine formation in this mutant is very rapid owing to the high reactivity of radicals formed on T(6). H(2)O(2)-dependent formation of CCP-cytochrome c heterodimers was observed for both CCP(MI) and W191F in the presence of ferricytochrome c, the oxidized form of CCP's donor substrate. Interestingly, no H(2)O(2)-dependent cytochrome crosslinking to the W51F mutant was observed, even though this mutant underwent extensive homocrosslinking. The translocation of oxidizing equivalents from the heme to the surface residues of CCP is discussed in terms of an antioxidant role for CCP. PMID:12589560

  10. Wind speeds on extrasolar worlds

    NASA Astrophysics Data System (ADS)

    Allers, Katelyn; Biller, Beth; Vos, Johanna; Williams, Peter; Berger, Edo

    2016-08-01

    We propose for photometric monitoring observations of 2MASS J10475385+2124234 and WISE J112254.73+255021.5 using Spitzer/IRAC. 2MASS J1047+21 and WISE J1122+25 are late spectral type (T6.5 and T6) radio emitters and have measured radio periods of 1.77 hrs and 1.30 hrs, respectively. Our proposed observations will not only characterize the variability of the two coolest known radio emitters but also provide a unique opportunity to measure the first wind speeds for brown dwarfs. Spitzer is currently the only facility capable of the photometric stability, continuous observations and 4.5 micron sensitivity necessary for the success of our program.

  11. Do all BPS black hole microstates carry zero angular momentum?

    NASA Astrophysics Data System (ADS)

    Chowdhury, Abhishek; Garavuso, Richard S.; Mondal, Swapnamay; Sen, Ashoke

    2016-04-01

    From the analysis of the near horizon geometry and supersymmetry algebra it has been argued that all the microstates of single centered BPS black holes with four unbroken supersymmetries carry zero angular momentum in the region of the moduli space where the black hole description is valid. A stronger form of the conjecture would be that the result holds for any sufficiently generic point in the moduli space. In this paper we set out to test this conjecture for a class of black hole microstates in type II string theory on T 6, represented by four stacks of D-branes wrapped on various cycles of T 6. For this system the above conjecture translates to the statement that the moduli space of classical vacua must be a collection of points. Explicit analysis of systems carrying a low number of D-branes supports this conjecture.

  12. Discrete Abelian gauge symmetries and axions

    NASA Astrophysics Data System (ADS)

    Honecker, Gabriele; Staessens, Wieland

    2015-07-01

    We combine two popular extensions of beyond the Standard Model physics within the framework of intersecting D6-brane models: discrete ℤn symmetries and Peccei-Quinn axions. The underlying natural connection between both extensions is formed by the presence of massive U(1) gauge symmetries in D-brane model building. Global intersecting D6-brane models on toroidal orbifolds of the type T6/ℤ2N and T6/ℤ2 × ℤ2M with discrete torsion offer excellent playgrounds for realizing these extensions. A generation-dependent ℤ2 symmetry is identified in a global Pati-Salam model, while global left-right symmetric models give rise to supersymmetric realizations of the DFSZ axion model. In one class of the latter models, the axion as well as Standard Model particles carry a non-trivial ℤ3 charge.

  13. Preliminary Investigation of Zircaloy-4 as a Research Reactor Cladding Material

    SciTech Connect

    Brian K Castle

    2012-05-01

    As part of a scoping study for the ATR fuel conversion project, an initial comparison of the material properties of Zircaloy-4 and Aluminum-6061 (T6 and O-temper) is performed to provide a preliminary evaluation of Zircaloy-4 for possible inclusion as a candidate cladding material for ATR fuel elements. The current fuel design for the ATR uses Aluminum 6061 (T6 and O temper) as a cladding and structural material in the fuel element and to date, no fuel failures have been reported. Based on this successful and longstanding operating history, Zircaloy-4 properties will be evaluated against the material properties for aluminum-6061. The preliminary investigation will focus on a comparison of density, oxidation rates, water chemistry requirements, mechanical properties, thermal properties, and neutronic properties.

  14. Axial-Load Fatigue Properties of 24S-T and 75S-T Aluminum Alloy as Determined in Several Laboratories

    NASA Technical Reports Server (NTRS)

    Grover, H J; Hyler, W S; Kuhn, Paul; Landers, Charles B; Howell, F M

    1954-01-01

    In the initial phase of a NACA program on fatigue research, axial-load tests on 24S-T3 and 75S-T6 aluminum-alloy sheet have been made at the Battelle Memorial Institute and at the Langley Aeronautical Laboratory of the National Advisory Committee for Aeronautics. The test specimens were polished and unnotched. The manufacturer of the material, the Aluminum Company of America, has made axial-load tests on 24S-T4 and 75S-T6 rod material. The test techniques used at the three laboratories are described in detail; the test results are presented and are compared with each other and with results obtained on unpolished sheet by the National Bureau of Standards. (author)

  15. Evaluation of Johnson-Cook model constants for aluminum based particulate metal matrix composites

    NASA Astrophysics Data System (ADS)

    Hilfi, H.; Brar, N. S.

    1996-05-01

    High strain rate and high temperature response of three types of aluminum based particulate metal matrix ceramic composites is investigated by performing split Hopkinson pressure bar (SHPB) experiments. The composites are: NGP-2014 (15% SiC), NGT-6061 (15% SiC), and NGU-6061 (15% Al2O3), in which all the reinforcement materials are percentage by volume. Johnson-Cook constitutive model constants are evaluated from the high strain rate/high temperature data and implemented in a two dimensional finite element computer code (EPIC-2D) to simulate the penetration of an ogive nose tungsten projectile (23 grams) at a velocity 1.17 km/sec into the base 6061-T6 aluminum alloy and the composite NGU-6061. The simulated penetrations in the composite and in 6061-T6 aluminum agree with in 2%, in both materials, with the measured values.

  16. Fracture toughness of an Al-Li-Cu-In alloy

    SciTech Connect

    Wagner, J.A.; Gangloff, R.P. Virginia, University, Charlottesville )

    1992-06-01

    The crack initiation and growth fracture toughness of select AL-Li-Cu alloy variants are characterized and elucidated. Conventionally processed plates form large DC cast ingots are investigated to eliminate the variation in microstructure associated with laboratory scale and SPF-processed material. Fracture resistance is characterized using the J-integral method to establish crack initiation and growth behavior at 25 and -185 C. It is shown that state-of-the-art 2090-T81 has superior toughness compared to 2090 + In-T6 at both test temperatures, with the low toughness of 2090 + In-T6 associated with intersubgranular fracture attributed to a high density of subboundary precipitates. 21 refs.

  17. Fracture toughness of an Al-Li-Cu-In alloy

    NASA Technical Reports Server (NTRS)

    Wagner, John A.; Gangloff, Richard P.

    1992-01-01

    The crack initiation and growth fracture toughness of select AL-Li-Cu alloy variants are characterized and elucidated. Conventionally processed plates form large DC cast ingots are investigated to eliminate the variation in microstructure associated with laboratory scale and SPF-processed material. Fracture resistance is characterized using the J-integral method to establish crack initiation and growth behavior at 25 and -185 C. It is shown that state-of-the-art 2090-T81 has superior toughness compared to 2090 + In-T6 at both test temperatures, with the low toughness of 2090 + In-T6 associated with intersubgranular fracture attributed to a high density of subboundary precipitates.

  18. The Vibrio cholerae type VI secretion system employs diverse effector modules for intraspecific competition

    PubMed Central

    Unterweger, Daniel; Miyata, Sarah T.; Bachmann, Verena; Brooks, Teresa M.; Mullins, Travis; Kostiuk, Benjamin; Provenzano, Daniele; Pukatzki, Stefan

    2014-01-01

    Vibrio cholerae is a Gram-negative bacterial pathogen that consists of over 200 serogroups with differing pathogenic potential. Only strains that express the virulence factors cholera toxin (CT) and toxin-coregulated pilus (TCP) are capable of pandemic spread of cholera diarrhoea. Regardless, all V. cholerae strains sequenced to date harbour genes for the type VI secretion system (T6SS) that translocates effectors into neighbouring eukaryotic and prokaryotic cells. Here we report that the effectors encoded within these conserved gene clusters differ widely among V. cholerae strains, and that immunity proteins encoded immediately downstream from the effector genes protect their host from neighbouring bacteria producing corresponding effectors. As a consequence, strains with matching effector-immunity gene sets can coexist, while strains with different sets compete against each other. Thus, the V. cholerae T6SS contributes to the competitive behaviour of this species. PMID:24686479

  19. Picosecond time evolution of photoexcitations at 2.33 eV in α-sexithyenil thin films

    NASA Astrophysics Data System (ADS)

    Lanzani, G.; Danieli, R.; Muccini, M.; Taliani, C.

    1993-11-01

    Picosecond time dynamics of the isotropic as well as the anisotropic transient absorption saturation have been measured in an α-sexithyenil (T6) thin film at room temperature by photoinduced absorption and resonant Kerr-gate experiments. Strongly damped photoacoustical oscillations have been detected superimposed on the photobleaching signal, providing a way to evaluate the sound speed in T6 films along the normal to the substrate; VS~=16 Å/ps. A stretched exponential function has been used to describe the time recovery of the total photoexcited population yielding a time constant τ=3.5 ns with an exponent α=0.5. This is indicative of dispersive diffusion towards recombination centers via intermolecular hopping; the Kerr-gate transmission decay provides an estimate of the photoexcitation diffusion constant, namely, D=6×10-3 cm2/s.

  20. Spinal dural AV fistula: an unusual cause of chest pain

    PubMed Central

    Bioh, Gabriel; Bogle, Richard

    2014-01-01

    A 22 -year-old man presented with 6 months of sudden onset, incapacitating, left-sided chest pain occurring 1–2 times a week. The severity of the pain caused loss of consciousness several times leading to multiple fractures. Investigation with echocardiogram, exercise tolerance test, Holter monitor, chest X-ray and V/Q scan revealed no abnormality as did EEG and 48 h video telemetry. MRI of the thoracic and lumbar spine showed a spinal dural arteriovenous fistula (SDAVF) at the level of T6, confirmed on angiogram. The patient underwent division of the left T6 AV fistula. Following the operation, the patient has been completely pain free. Our patient, presenting in his early 20s does not fit the usual age demographic for SDAVF. A second atypical feature is his presentation with chest pain alone and no neurological symptoms. This case represents a rare presentation of SDAVF. PMID:24532234

  1. Tailoring of mechanical properties of hydroformed aluminum tubes

    SciTech Connect

    Hong, Sung-tae; Lavender, Curt A.

    2007-07-06

    Tailoring of the mechanical properties of hydroformed aluminum 6063-T4 tubes to those of aluminum 6063-T6 was performed by heat treatment. Quasi-static tensile tests and a SEM analysis were conducted to evaluate the change of the mechanical properties. The experimental results of the hydroformed tubes in T4 condition (before the heat treatment) show significant variations of the mechanical properties along the length due to the different extents of work hardening by hydroforming. The experimental results of the hydroformed tubes in T6 condition (after the heat treatment) show that the precipitation hardening successfully removed the effects of the non-uniform work hardening and resulted in the uniform mechanical properties in the tube.

  2. Interactions of satellite-speed helium atoms with satellite surfaces. 2: Energy distributions of reflected helium atoms

    NASA Technical Reports Server (NTRS)

    Liu, S. M.; Knuth, E. L.

    1976-01-01

    Energy transfer in collisions of satellite-speed (7,000 m/sec) helium atoms with a cleaned 6061-T6 satellite-type aluminum surface was investigated using the molecular-beam technique. The amount of energy transferred was determined from the measured energy of the molecular-beam and the measured spatial and energy distributions of the reflected atoms. Spatial distributions of helium atoms scattered from a 6061-T6 aluminum surface were measured. The scattering pattern exhibits a prominent backscattering, probably due to the gross surface roughness and/or the relative lattice softness of the aluminum surface. Energy distributions of reflected helium atoms from the same surface were measured for six different incidence angles. For each incidence angle, distributions were measured at approximately sixty scattering positions. At a given scattering position, the energy spectra of the reflected helium atoms and the background gas were obtained using the retarding-field energy analyzer.

  3. Impact and residual fatigue behavior of ARALL and AS6/5245 composite material

    NASA Technical Reports Server (NTRS)

    Johnson, W. S.

    1989-01-01

    The impact sensitivity of aramide fiber-reinforced aluminum laminates (ARALL) was investigated by testing two types of ARALL (7075 aluminum prestrained and 2024 aluminum not prestrained), via static indentation, and the results were compared to those of sheet aluminum alloys 7075-T6 and 2024-T3 and to a state of the art composite AS6/5245. It was found that the impact resistance of the two ARALL samples was inferior to that of monolithic sheet aluminum samples, although the ARALL material made with 2024-T3 aluminum was superior to that made with 7075-T6 aluminum. The impact damage resistance of ARALL materials was at least equal to that of AS6/5245, and the AS6/5245 had higher residual tension-tension fatigue strength after impact than the ARALL samples. It was also found that the prestraining of the ARALL reduced the fatigue growth of impact damage.

  4. Fatigue testing welded joints for P/M Al-matrix composites

    NASA Astrophysics Data System (ADS)

    Harrigan, William C.

    1994-07-01

    To meet their need for high stiffness, many bicycles currently rely on aluminum-matrix composites. The highest strength and highest stiffness form of these material, 6092/B4C/15p, is produced by powder metallurgy techniques. The bicycles are tungsten inert-gas welded and fully heat treated after welding. A test technique has been developed to assess the static and fatigue properties of welded joints. This test technique has revealed the increased stiffness and strength of a 6092/B4C/15p-T6P composite tube joint as compared with a 6061-T6 aluminum one. This test technique is currently being used to identify fatigue properties for both tube joints.

  5. Galvanic corrosion of aluminum-matrix composites. Technical report No. 2, 1 Mar-31 Dec 90

    SciTech Connect

    Hihara, L.H.; Latanision, R.M.

    1991-02-01

    Galvanic-corrosion rates of Al-matrix composites were high in aerated chloride-containing solutions. Oxygen reduction was found to be the primary cathodic reaction. Aluminum corroded by pitting. The type of noble constituent (i.e., graphite, SiC, or TiB{sub 2}) also affected galvanic-corrosion rates. For example, results indicated that the galvanic-corrosion rate of Al should be about 30 times greater when coupled to graphite than when coupled to SiC or TiB{sub 2}. In dearated solutions, galvanic corrosion was negligible even if chlorides were present. The galvanic-corrosion rates were determined using the zero-resistance ammeter technique and from potentiodynamic polarization diagrams of ultrapure Al, 6061-T6 Al, graphite fiber, SiC, TiB2, and a commercial graphite fiber/6061-T6 Al metal-matrix composite.

  6. Influence of DNA End Structure on the Mechanism of Initiation of DNA Unwinding by the E. coli RecBCD and RecBC Helicases

    PubMed Central

    Wu, Colin G.; Lohman, Timothy M.

    2011-01-01

    E. coli RecBCD is a bipolar DNA helicase possessing two motor subunits (RecB, a 3' to 5' translocase and RecD, a 5' to 3' translocase), that is involved in the major pathway of recombinational repair. Previous studies indicated that the minimal kinetic mechanism needed to describe the ATP-dependent unwinding of blunt-ended DNA by RecBCD in vitro is a sequential n-step mechanism with two to three additional kinetic steps prior to initiating DNA unwinding. Since RecBCD can “melt-out” ~ six bp upon binding to the end of a blunt-ended DNA duplex in a Mg2+-dependent but ATP-independent reaction, we have investigated the effects of non-complementary single-stranded (ss) DNA tails (3'-(dT)6 and 5'-(dT)6 or 5'-(dT)10) on the mechanism of RecBCD and RecBC unwinding of duplex DNA using rapid kinetic methods. As with blunt-ended DNA, RecBCD unwinding of DNA possessing 3'-(dT)6 and 5'-(dT)6 non-complementary ssDNA tails is well described by a sequential n-step mechanism with the same unwinding rate (mkU = 774 ± 16 bp s−1) and kinetic step-size (m = 3.3 ± 1.3 bp), yet two to three additional kinetic steps are still required prior to initiation of DNA unwinding (kC = 45 ± 2 s−1). However, when the non-complementary 5'-ssDNA tail is extended to ten nucleotides (5'-(dT)10 and 3'-(dT)6), the DNA end structure for which RecBCD displays optimal binding affinity, the additional kinetic steps are no longer needed, although a slightly slower unwinding rate (mkU = 538 ± 24 bp s−1) is observed with a similar kinetic step-size (m = 3.9 ± 0.5 bp). The RecBC DNA helicase (without the RecD subunit) does not initiate unwinding efficiently from a blunt DNA end. However, RecBC does initiate well from a DNA end possessing non-complementary twin 5'- dT6 and 3'-dT6 tails, and unwinding can be described by a simple uniform n-step sequential scheme, without the need of the additional kC initiation steps, with a similar kinetic step size (m = 4.4 ± 1.7 bp), and unwinding rate (mkobs

  7. Potency classification of topical corticosteroids: modern perspectives.

    PubMed

    Ashworth, J

    1989-01-01

    The effects of topical corticosteroid therapy upon human epidermal Langerhans cell surface markers were studied. The reduction in numbers of human leukocyte antigen-DR+/T6+ Langerhands cells proved to be a potency-related effect and Langerhans cell enumeration may therefore have some use as an adjunct in the assessment of steroid potency. Further studies showed that corticosteroid therapy also reduced the function of Langerhans cells in terms of epidermal cell alloantigen-presenting capacity. However, experimental variation and the high antigen-presenting potency of residual flow cytomterically sorted human leukocyte antigen-DR+/T6+ Langerhans cells following steroid application (1) mean that such functional assessments of epidermal cell alloantigen-presenting capacity cannot be recommended as an easily reproducible method for measuring steroid potency. PMID:2696307

  8. The effect of pre-existing corrosion on the fatigue cracking behavior of aluminum alloys

    SciTech Connect

    Hagerdorn, E.L.; Koch, G.H.

    1996-10-01

    In order to assess the effect of preexisting corrosion on the fatigue crack behavior of aluminum alloys 2024-T3 and 7074-T6 crack initiation and growth data were obtained using fracture mechanics specimens. These specimens incorporated mechanically thinned areas and areas that had been preexposed to environments which produced various degrees of pitting or exfoliation corrosion. The data obtained from these laboratory experiments indicate that specific corrosive was most pronounced in the fatigue cracking behavior of aluminum alloys. The effect of preexisting corrosion was most pronounced in the fatigue crack initiation stage. Based on the results of this study, it was concluded that the effect of preexisting corrosion on the fatigue cracking behavior of both aluminum alloys 2024-T3 and 7075-T6 is a combination of stress concentrations as a result of material loss, and altered material properties, possible as a result of hydrogen entry into the lattice.

  9. The computer as a physical system: A microscopic quantum mechanical Hamiltonian model of computers as represented by Turing machines

    NASA Astrophysics Data System (ADS)

    Benioff, Paul

    1980-05-01

    In this paper a microscopic quantum mechanical model of computers as represented by Turing machines is constructed. It is shown that for each number N and Turing machine Q there exists a Hamiltonian H N Q and a class of appropriate initial states such that if c is such an initial state, then ψ Q N (t)=exp(-1 H N Q t) ψ Q N (0) correctly describes at times t 3, t 6,⋯, t 3N model states that correspond to the completion of the first, second, ⋯, Nth computation step of Q. The model parameters can be adjusted so that for an arbitrary time interval Δ around t 3, t 6,⋯, t 3N, the "machine" part of ψ Q N (t) is stationary.

  10. A dumbbell-shaped meningioma mimicking a schwannoma in the thoracic spine.

    PubMed

    Kim, Myeong-Soo; Eun, Jong-Pil; Park, Jeong-Soo

    2011-09-01

    A 50-year-old man presented bilateral hypesthesia on and below the T6 dermatome and paresthesia. Magnetic resonance imaging (MRI) showed an intraspinal extradural tumor, which located from the 6th thoracic vertebral body to the upper margin of the 7th vertebral body, continuing dumbbell-like through the intervertebral foramen into the right middle thorax suggesting a neurogenic tumor (neurofibroma or neurilemmoma). With the patient in a prone position, we exposed and excised the tumor via a one stage posterior approach through a hemi-laminictomy of T6. Histologic examination showed a grade 1 meningothelial meningioma, according to the World Health Organization classification. Initially, we assumed the mass was a schwannoma because of its location and dumbbell shape. However, the tumor was actually a meningioma. Postoperatively, hypesthesia resolved completely and motor power of the leg gradually full recovered. A postoperative MRI revealed no evidence of residual tumor. PMID:22102962

  11. Near surface modification of aluminum alloy induced by laser shock processing

    NASA Astrophysics Data System (ADS)

    Saklakoglu, Nursen; Gencalp Irizalp, Simge; Akman, Erhan; Demir, Arif

    2014-12-01

    This paper investigates the influences of near surface modification induced in 6061-T6 aluminum alloy by laser shock processing (LSP). The present study evaluates LSP with a Q-switched Nd:YAG low power laser using water confinement medium and absorbent overlay on the workpiece. The near surface microstructural change of 6061-T6 alloy after LSP was studied. The residual stress variation throughout the depth of the workpiece was determined. The results showed an improvement of the material resistance to pit formation. This improvement may be attributed to compressive residual stress and work-hardening. The size and number of pits revealed by immersion in an NaOH-HCl solution decreased in comparison with the untreated material.

  12. Three-D crater analysis of LDEF impact features from stereo imagery

    NASA Technical Reports Server (NTRS)

    Sapp, Clyde A.; See, Thomas H.; Zolensky, Michael E.

    1993-01-01

    The preliminary results from attempts to derive depth and diameter information from digitized stereo images of impact features on the LDEF are reported. Contrary to our prior assumption, we find that impact craters in the T6 A1 alloy are not paraboloid in cross section, but rather are better described by a 6th-order polynomial curve. We explore the implications of this discovery.

  13. Histone H3 phosphorylation in GBM: a new rational to guide the use of kinase inhibitors in anti-GBM therapy.

    PubMed

    Pacaud, Romain; Cheray, Mathilde; Nadaradjane, Arulraj; Vallette, François M; Cartron, Pierre-François

    2015-01-01

    Histones post-translational modifications (PTMs) are crucial components of diverse processes that modulate chromatin. Among the histones PTMs, the histones phosphorylation appears such crucial since it plays a significant role into DNA repair structure, transcription and chromatin compaction during cell division and apoptosis. However, little is known about the prognostic value of the histone phosphorylation in human cancer. This point could be considerate such as an important gap in anti-cancer therapy since the use of adequate kinase inhibitors could remedy to the aberrant histone phosphorylation associated with a poor prognosis factor. To remedy at this situation, we analyzed the phosphorylation level of histone H3 at the residues T3, T6, S10, S28, Y41 and T45 in a collection of 42 glioblastoma multiformes (GBM). Our data indicated that the high level of pH3T6, pH3S10 and pH3Y41 are signatures associated with a poor prognosis of overall survival (OS) of GBM treated with the "temozolomide and irradiation standard" treatment of GBM (named TMZ+Irad treatment). Our data also showed that these signatures are correlated with the high activity of kinases already described as writers of the pH3T6, pH3S10 and pH3Y41 i.e. the PKC, Aurora-B and JAK2, respectively. Finally, our analysis revealed that the use of Enzastaurin, AZD1152, and AZD1480 abrogated the high level of pH3T6, pH3S10 and pH3Y41 while increasing the sensitivity to the "temozolomide and irradiation"-induced cell death. To conclude, it appears that this work provides biomarkers for patient stratification for a therapy including kinase inhibitors. PMID:25553095

  14. Intestinal microecology associated with fluoride resistance capability of the silkworm (Bombyx mori L.).

    PubMed

    Li, Guan-Nan; Xia, Xue-Juan; Tang, Wen-Chao; Zhu, Yong

    2016-08-01

    The silkworm (Bombyx mori L.) is an ideal model of Lepidoptera. However, the diversity and function of the intestinal microbiota in the gut of silkworm remain largely unknown. Changes in the intestinal microecology in fluoride-resistant strain T6 and fluoride-susceptible strain 734 of the silkworm in response to fluoride exposure were investigated. T6 and 734 were treated with 200 mg/kg fluoride (designated as T6-T and 734-T groups) and deionized water (designated as T6-C and 734-C groups). Culture-dependent approach revealed that the numbers of intestinal bacteria in the 734-T group significantly decreased compared with that in the 734-C group (4.8 ± 0.6 × 10(7) CFU/mL vs. 7.5 ± 0.7 × 10(7) CFU/mL; P < 0.05). Analyses of the intestinal content pH showed that the pH decreased in the 734-T group only. Additionally, SCFA concentrations significantly decreased in both treatment groups compared with the control groups. High-throughput sequencing indicated that the intestinal microbiota in the 734-T group was significantly more diverse than those in the other groups. The bacterial community was composed of two dominant groups (Firmicutes and Proteobacteria). Principal component analyses revealed a significant difference in the composition of the intestinal microbiota in the 734-T group compared with those in the other groups. Thaumarchaeota and Euryarchaeota were more abundant in the 734-T group, but they were less abundant in the other groups. This study enhances our understanding about the diversity and function of silkworm intestinal microbiota in response to fluoride exposure among silkworm strains with diverse resistance. PMID:27147533

  15. Solid State Bonding Mechanics In Extrusion And FSW: Experimental Tests And Numerical Analyses

    SciTech Connect

    Buffa, G.; Fratini, L.; Donati, L.; Tomesani, L.

    2007-04-07

    In the paper the authors compare the different solid state bonding mechanics for both the processes of hollow profiles extrusion and Friction Stir Welding (FSW), through the results obtained from a wide experimental campaign on AA6082-T6 aluminum alloys. Microstructure evaluation, tensile tests and micro-hardness measurements realized on specimens extracted by samples of the two processes are discussed also by means of the results obtained from coupled FEM simulation of the processes.

  16. Growth Arrest by Trehalose-6-Phosphate: An Astonishing Case of Primary Metabolite Control over Growth by Way of the SnRK1 Signaling Pathway1[C][W][OA

    PubMed Central

    Delatte, Thierry L.; Sedijani, Prapti; Kondou, Youichi; Matsui, Minami; de Jong, Gerhardus J.; Somsen, Govert W.; Wiese-Klinkenberg, Anika; Primavesi, Lucia F.; Paul, Matthew J.; Schluepmann, Henriette

    2011-01-01

    The strong regulation of plant carbon allocation and growth by trehalose metabolism is important for our understanding of the mechanisms that determine growth and yield, with obvious applications in crop improvement. To gain further insight on the growth arrest by trehalose feeding, we first established that starch-deficient seedlings of the plastidic phosphoglucomutase1 mutant were similarly affected as the wild type on trehalose. Starch accumulation in the source cotyledons, therefore, did not cause starvation and consequent growth arrest in the growing zones. We then screened the FOX collection of Arabidopsis (Arabidopsis thaliana) expressing full-length cDNAs for seedling resistance to 100 mm trehalose. Three independent transgenic lines were identified with dominant segregation of the trehalose resistance trait that overexpress the bZIP11 (for basic region/leucine zipper motif) transcription factor. The resistance of these lines to trehalose could not be explained simply through enhanced trehalase activity or through inhibition of bZIP11 translation. Instead, trehalose-6-phosphate (T6P) accumulation was much increased in bZIP11-overexpressing lines, suggesting that these lines may be insensitive to the effects of T6P. T6P is known to inhibit the central stress-integrating kinase SnRK1 (KIN10) activity. We confirmed that this holds true in extracts from seedlings grown on trehalose, then showed that two independent transgenic lines overexpressing KIN10 were insensitive to trehalose. Moreover, the expression of marker genes known to be jointly controlled by SnRK1 activity and bZIP11 was consistent with low SnRK1 or bZIP11 activity in seedlings on trehalose. These results reveal an astonishing case of primary metabolite control over growth by way of the SnRK1 signaling pathway involving T6P, SnRK1, and bZIP11. PMID:21753116

  17. Temperature field acquisition during gas metal arc welding using thermocouples, thermography and fibre Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Moreira, P. M. G. P.; Frazão, O.; Tavares, S. M. O.; de Figueiredo, M. A. V.; Restivo, M. T.; Santos, J. L.; de Castro, P. M. S. T.

    2007-03-01

    The paper presents the application of temperature acquisition systems integrating thermocouples, a thermographic camera and fibre Bragg grating (FBG) sensors in gas metal arc welding (GMAW) process, MIG (metal inert gas) welding type. Efficient procedures to use FBG sensors and thermocouples were developed. The paper presents and compares measurements made in welded plates of aluminium alloy 6082-T6. Tests were performed in both plate surfaces and good agreement between the three techniques was found.

  18. Trehalose-6-phosphate and SnRK1 kinases in plant development and signaling: the emerging picture

    PubMed Central

    Tsai, Allen Y.-L.; Gazzarrini, Sonia

    2014-01-01

    Carbohydrates, or sugars, regulate various aspects of plant growth through modulation of cell division and expansion. Besides playing essential roles as sources of energy for growth and as structural components of cells, carbohydrates also regulate the timing of expression of developmental programs. The disaccharide trehalose is used as an energy source, as a storage and transport molecule for glucose, and as a stress-responsive compound important for cellular protection during stress in all kingdoms. Trehalose, however, is found in very low amounts in most plants, pointing to a signaling over metabolic role for this non-reducing disaccharide. In the last decade, trehalose-6-phosphate (T6P), an intermediate in trehalose metabolism, has been shown to regulate embryonic and vegetative development, flowering time, meristem determinacy, and cell fate specification in plants. T6P acts as a global regulator of metabolism and transcription promoting plant growth and triggering developmental phase transitions in response to sugar availability. Among the T6P targets are members of the Sucrose-non-fermenting1-related kinase1 (SnRK1) family, which are sensors of energy availability and inhibit plant growth and development during metabolic stress to maintain energy homeostasis. In this review, we will discuss the opposite roles of the sugar metabolite T6P and the SnRK1 kinases in the regulation of developmental phase transitions in response to carbohydrate levels. We will focus on how these two global regulators of metabolic processes integrate environmental cues and interact with hormonal signaling pathways to modulate plant development. PMID:24744765

  19. Effects of Post-Weld Heat Treatment on the Mechanical Properties of Similar- and Dissimilar-Alloy Friction Stir Welded Blanks

    SciTech Connect

    Zadpoor, Amir Abbas; Sinke, Jos

    2011-01-17

    Friction stir welding is a solid state joining process with relatively low welding temperatures. Nevertheless, the mechanical properties of friction stir welded blanks are degraded after welding. Indeed, both strength and ductility of the welds are decreased after welding. Often, the resulting friction stir welded blanks need to be formed to their final structural shape. Therefore, the formability of friction stir welded blanks is of primary importance in the manufacturing of structural parts. This paper studies how the mechanical properties and particularly formability of friction stir welded blanks can be improved by applying a post weld heat treatment. Two aluminum alloys from 2000 and 7000 series, namely 2024-T3 and 7075-T6, are selected for the study. The sheet thickness of both materials is 2,0 mm. The selected alloys are welded in three configurations: 2024-T3 and 2024-T3, 7075-T6 and 7075-T6, and 2024-T3 and 7075-T6. The resulting welds are naturally aged for a few months. Three sets of standard dog bone shape tensile test specimens are then machined from the welds. The first set of the specimens is tested without any heat treatment. The second set of the specimens is solution heat treated and quenched before testing. The third set of the specimens is solution heat treated, quenched, and naturally aged for a week before testing. The mechanical properties of the three different sets of specimens are compared with each other. It is shown that careful selection of post weld heat-treatment can greatly improve the formability of friction stir welded blanks.

  20. Indole-3-carbinol enhances the resolution of rat liver fibrosis and stimulates hepatic stellate cell apoptosis by blocking the inhibitor of κB kinase α/inhibitor of κB-α/nuclear factor-κB pathway.

    PubMed

    Ping, Jie; Gao, Ai-mei; Qin, Hai-quan; Wei, Xiao-ning; Bai, Jing; Liu, Lian; Li, Xiao-hai; Li, Rui-wen; Ao, Ying; Wang, Hui

    2011-11-01

    Hepatic stellate cells (HSC) play a pivotal role in liver fibrosis, and the clearance of activated HSC by apoptosis is associated with the resolution of liver fibrosis. The development of strategies that promote this process in a selective way is therefore important. We evaluated the effects of indole-3-carbinol (I3C), a nutritional component derived from vegetables from the Brassica family, on liver fibrosis and HSC apoptosis. The in vivo therapeutic effects of I3C were monitored in three rat models of liver fibrosis induced by porcine serum, bile duct ligation, or multiple hepatotoxic factors, and its proapoptotic effect and molecular mechanism were studied in vitro in HSC-T6, a rat HSC line. The results showed that I3C treatment significantly reduced the number of activated HSC in the livers of rats with liver fibrosis. In histopathology, I3C reduced hepatocyte degeneration and necrosis, accelerated collagen degradation, and promoted the reversal of liver fibrosis. I3C prescribed to HSC-T6 resulted in morphologic alterations typical of apoptosis and DNA cleavage to a nucleosomal ladder. Moreover, I3C significantly increased the HSC-T6 apoptosis rate and the expression ratio of Bax to Bcl-2. High-throughput protein array analysis indicated that the tumor necrosis factor-α/nuclear factor-κB (NF-κB) signal pathway participated in I3C-induced HSC-T6 apoptosis. Western blot and electrophoretic mobility-shift assay confirmed that I3C inhibited the phosphorylation of inhibitor of κB kinase α and inhibitor of κB-α and NF-κB DNA binding activity. In conclusion, I3C could promote the reverse process of liver fibrosis in vivo and induce apoptosis of activated HSC in vitro, which indicates the use of I3C as a potential therapeutic agent in liver fibrosis treatment. PMID:21862660

  1. 77 FR 58814 - Privacy Act of 1974 System of Records Notice

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-24

    ... registration applicants or registered firms or other entities, including business, home and cell phone numbers... routine uses numbered 1 through 19 published at 76 FR 5974 (Feb. 2, 2011). These blanket routine uses..., 7 U.S.C. 1 et seq., including Sections 4g, 4i, 8, 7 U.S.C. 4t, 6g, 6i, 12, 2(d), 76 FR 43851...

  2. Neferine inhibits cultured hepatic stellate cell activation and facilitates apoptosis: A possible molecular mechanism.

    PubMed

    Ding, Hui; Shi, Jinghong; Wang, Ying; Guo, Jia; Zhao, Juhui; Dong, Lei

    2011-01-10

    Neferine is a major alkaloid component of "Lian Zi Xin", embryos of the seeds of Nelumbo nucifera Gaertner, Nymphaeaceae. Previous studies have shown that neferine has an inhibitory effect on pulmonary fibrosis through its anti-inflammatory and anti-oxidative activities and inhibition of cytokines and NF-κB. However, it is unknown whether neferine also has an inhibitory effect on liver fibrosis through inhibition of TGF-β1 and collagen I and facilitation of apoptosis of hepatic stellate cells. This study examined the effects of neferine on cultured hepatic stellate (HSC-T6) cells and explored its possible action mechanisms by means of MTT assay, enzyme-linked immunosorbent assay, flow-cytometric annexin V-PI assay and Hoechst 33258 staining, as well as real-time PCR and western blotting. The results showed that neferine administration (2, 4, 6, 8 and 10μmol/l) significantly decreased the TGF-β1 and collagen I produced in HSC-T6 cells, and increased the HSC-T6 cell apoptosis in a dose-dependent manner. Neferine treatment for 48h at concentrations of 6 and 10μmol/l significantly increased Bax and caspase 3 mRNAs and proteins, and reduced Bcl2 and alpha-smooth muscle actin (α-SMA) mRNAs and proteins. Our data indicate that neferine efficiently inhibits cultured HSC-T6 cell activation and induces apoptosis by increasing Bax and caspase 3 expression via the mitochondrial pathway. PMID:20969858

  3. The PP-motif in luminal loop 2 of ZnT transporters plays a pivotal role in TNAP activation.

    PubMed

    Fujimoto, Shigeyuki; Tsuji, Tokuji; Fujiwara, Takashi; Takeda, Taka-Aki; Merriman, Chengfeng; Fukunaka, Ayako; Nishito, Yukina; Fu, Dax; Hoch, Eitan; Sekler, Israel; Fukue, Kazuhisa; Miyamae, Yusaku; Masuda, Seiji; Nagao, Masaya; Kambe, Taiho

    2016-09-01

    Secretory and membrane-bound zinc-requiring enzymes are thought to be activated by binding zinc in the early secretory pathway. One such enzyme, tissue-non-specific alkaline phosphatase (TNAP), is activated through a two-step mechanism, via protein stabilization and subsequent enzyme activation through metalation, by ZnT5-ZnT6 heterodimers or ZnT7 homodimers. However, little is known about the molecular basis underlying the activation process. In the present study, we found that the di-proline motif (PP-motif) in luminal loop 2 of ZnT5 and ZnT7 is important for TNAP activation. TNAP activity was significantly reduced in cells lacking ZnT5-ZnT6 heterodimers and ZnT7 homodimers [triple knockout (TKO) cells]. The decreased TNAP activity was restored by expressing hZnT5 with hZnT6 or hZnT7, but significantly less so (almost 90% less) by expressing mutants thereof in which the PP-motif was mutated to alanine (PP-AA). In TKO cells, overexpressed hTNAP was not completely activated, and it was converted less efficiently into the holo form by expressing a PP-AA mutant of hZnT5 with hZnT6, whose defects were not restored by zinc supplementation. The zinc transport activity of hZnT7 was not significantly impaired by the PP-AA mutation, indicating that the PP-motif is involved in the TNAP maturation process, although it does not control zinc transport activity. The PP-motif is highly conserved in ZnT5 and ZnT7 orthologues, and its importance for TNAP activation is conserved in the Caenorhabditis elegans hZnT5 orthologue CDF5. These results provide novel molecular insights into the TNAP activation process in the early secretory pathway. PMID:27303047

  4. Corrosion Behaviour of A380 Aluminiun Alloy by Semi-Solid Rheocasting

    SciTech Connect

    Forn, A.; Ruperez, E.; Baile, M. T.; Campillo, M.; Menargues, S.; Espinosa, I.

    2007-04-07

    A comparative study was performed on the corrosion behavior of a component of A380 aluminium alloy obtained by Semi-Solid Rheocasting (SSR). The effect of heat treatments T5 and T6 on corrosion resistance was compared with components without heat treatment by SSR processes. Corrosion studies were performed using an acetic acid salt spray test, impedance measurements and polarization curves using a 3,5%Na Cl test solution. The corrosion progress is described by micrographic analysis.

  5. [Effects of nitrogen management on yield, quality, nitrogen accumulation and its transportation of watermelon in gravel-mulched field].

    PubMed

    Ma, Zhong-ming; Du, Shao-ping; Xue, Liang

    2015-11-01

    The effects of nitrogen management on yield, quality, nitrogen and dry matter accumulation and transportation of watermelon in sand field were studied based on a field experiment. The results showed that too low or too high basal nitrogen fertilzation was unfavorable to seedling growth of watermelon in sand field, and no nitrogen application at vine extension or fruiting stages limited the formation of 'source' or 'sink'. At the same nitrogen rate, compared with the traditional T1 treatment (30% basal N fertilizer + 70% N fertilizer in vine extension), the nitrogen and dry matter accumulation of vegetative organs of T4 treatment (30% basal N fertilizer + 30% N fertilizer in vine extension + 40% N fertilizer in fruiting) and T6 treatment (100% basal N fertilizer + NAM) were reduced significantly, but the nitrogen and dry matter accumulation of fruit were increased significantly in the flushing period. The nitrogen transportation ratio and nitrogen contribution ratio of T4 were 33.6% and 12.0%, respectively. Compared to T1, the nitrogen harvest index, nitrogen fertilizer partial factor productivity and nitrogen fertilizer recovery efficiency of T4 and T6 treatments increased by 14.1% and 12.7%, 11.6% and 12.5%, 5.3% and 8.7%, respectively, and yield of watermelon increased by 11.6% and 12.5%, the soluble sugar, effective acid, the ratio of sugar and acid, Vc content increased by 16.5% and 11.7%, 4.5% and 2.8%, 19.4% and 13.4%, 35.6% and 19.0%, respectively. Therefore, T4 and T6 treatments were the optimal nitrogen fertilizer management mode which could not only achieve high yield and quality but also obtain high nitrogen fertilizer use efficiency in sand field. T6 treatment was the best nitrogen fertilizer management mode considering reduction of fertilizing labor intensity and extending service time of gravel-mulched field. PMID:26915190

  6. Electron Positron Proton Spectrometer for use at Laboratory for Laser Energetics

    SciTech Connect

    Ayers, S L

    2010-04-07

    The Electron Positron Proton Spectrometer (EPPS) is mounted in a TIM (Ten-Inch Manipulator) system on the Omega-60 or Omega-EP laser facilities at the University of Rochester, Laboratory for Laser Energetics (LLE), when in use, see Fig. 1. The Spectrometer assembly, shown in Fig. 2, is constructed of a steel box containing magnets, surrounded by Lead 6% Antimony shielding with SS threaded insert, sitting on an Aluminum 6061-T6 plate.

  7. An invasive and low virulent Edwardsiella tarda esrB mutant promising as live attenuated vaccine in aquaculture.

    PubMed

    Yang, Weizheng; Wang, Lixia; Zhang, Lingzhi; Qu, Jiangbo; Wang, Qiyao; Zhang, Yuanxing

    2015-02-01

    Edwardsiella tarda is a leading fish pathogen haunting worldwide aquaculture industry. In E. tarda, two-component system EsrA-EsrB positively regulates type III and VI secretion systems (T3SS and T6SS) and negatively regulates hemolysin EthA, which has been demonstrated to be essential for the invasion processes in fish. In order to develop a live attenuated vaccine (LAV) with high invasiveness to be practically and economically used as immersion-administered vaccine in aquaculture, here, we generated a random mutation library of esrB sequences by error-prone PCR and introduced them into the E. tarda esrB deletion mutant. The mutant YWZ47 with significantly increased hemolytic activity and low T3SS and T6SS secretion was screened. Phenotypes including extracellular protein profiles, invasion in macrophages, lethality toward fish, and infection kinetics were investigated in the wild-type strain EIB202 and the mutants ΔesrB, ΔT3SS, ΔT6SS, ΔT3SS/ΔT6SS, and YWZ47. Compared to the documented LAV strain ΔesrB, YWZ47 showed higher invasive capability and low in vivo virulence toward fish. Significantly higher relative percent survival (RPS) could be generated in turbot (Scophthalmus maximus) against the challenge of the wild-type EIB202 when inoculated through immersion route, and the RPS was comparable with that of ΔesrB through intraperitoneal (i.p.) injection inoculation. Two mutated points, K167M and H197L, were found by sequence analysis of EsrBYWZ47 variant. These structural modifications underpin the variations in the regulatory functions of the mutant and wild-type EsrB. This study promoted understanding of virulence regulation by EsrB in E. tarda and presented a promising candidate of invasive attenuated vaccine used in aquaculture industries. PMID:25431010

  8. Cyclic Deformation Behavior of a Rare-Earth Containing Extruded Magnesium Alloy: Effect of Heat Treatment

    NASA Astrophysics Data System (ADS)

    Mirza, F. A.; Chen, D. L.; Li, D. J.; Zeng, X. Q.

    2015-03-01

    The present study was aimed at evaluating strain-controlled cyclic deformation behavior of a rare-earth (RE) element containing Mg-10Gd-3Y-0.5Zr (GW103K) alloy in different states (as-extruded, peak-aged (T5), and solution-treated and peak-aged (T6)). The addition of RE elements led to an effective grain refinement and weak texture in the as-extruded alloy. While heat treatment resulted in a grain growth modestly in the T5 state and significantly in the T6 state, a high density of nano-sized and bamboo-leaf/plate-shaped β' (Mg7(Gd,Y)) precipitates was observed to distribute uniformly in the α-Mg matrix. The yield strength and ultimate tensile strength, as well as the maximum and minimum peak stresses during cyclic deformation in the T5 and T6 states were significantly higher than those in the as-extruded state. Unlike RE-free extruded Mg alloys, symmetrical hysteresis loops in tension and compression and cyclic stabilization were present in the GW103K alloy in different states. The fatigue life of this alloy in the three conditions, which could be well described by the Coffin-Manson law and Basquin's equation, was equivalent within the experimental scatter and was longer than that of RE-free extruded Mg alloys. This was predominantly attributed to the presence of the relatively weak texture and the suppression of twinning activities stemming from the fine grain sizes and especially RE-containing β' precipitates. Fatigue crack was observed to initiate from the specimen surface in all the three alloy states and the initiation site contained some cleavage-like facets after T6 heat treatment. Crack propagation was characterized mainly by the characteristic fatigue striations.

  9. 27 CFR 9.140 - Atlas Peak.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... miles to the highest point of an unnamed peak of 1268 feet elevation in section 12, T. 6 N., R. 4 W. on... 12 and 13, T. 7 N., R. 4 W. on the Yountville U.S.G.S. map; (10) Then following the section boundary... elevation, located in section 10, T. N., R. 4 W.; (12) Then northwest in a straight line approximately...

  10. 27 CFR 9.140 - Atlas Peak.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... miles to the highest point of an unnamed peak of 1268 feet elevation in section 12, T. 6 N., R. 4 W. on... 12 and 13, T. 7 N., R. 4 W. on the Yountville U.S.G.S. map; (10) Then following the section boundary... elevation, located in section 10, T. N., R. 4 W.; (12) Then northwest in a straight line approximately...

  11. 10 CFR 2.1010 - Pre-License Application Presiding Officer.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... NRC adjudication has the requisite “need to know,” as defined in 10 CFR 73.2; (B) The individual has undergone an FBI criminal history records check, unless exempt under 10 CFR 73.22(b)(3) or 73.23(b)(3), as... Stop T-6E46, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, and otherwise following...

  12. Drug membrane transporters and CYP3A4 are affected by hypericin, hyperforin or aristoforin in colon adenocarcinoma cells.

    PubMed

    Šemeláková, M; Jendželovský, R; Fedoročko, P

    2016-07-01

    Our previous results have shown that the combination of hypericin-mediated photodynamic therapy (HY-PDT) at sub-optimal dose with hyperforin (HP) (compounds of Hypericum sp.), or its stable derivative aristoforin (AR) stimulates generation of reactive oxygen species (ROS) leading to antitumour activity. This enhanced oxidative stress evoked the need for an explanation for HY accumulation in colon cancer cells pretreated with HP or AR. Generally, the therapeutic efficacy of chemotherapeutics is limited by drug resistance related to the overexpression of drug efflux transporters in tumour cells. Therefore, the impact of non-activated hypericin (HY), HY-PDT, HP and AR on cell membrane transporter systems (Multidrug resistance-associated protein 1-MRP1/ABCC1, Multidrug resistance-associated protein 2-MRP2/ABCC2, Breast cancer resistance protein - BCRP/ABCG2, P-glycoprotein-P-gp/ABCC1) and cytochrome P450 3A4 (CYP3A4) was evaluated. The different effects of the three compounds on their expression, protein level and activity was determined under specific PDT light (T0+, T6+) or dark conditions (T0- T6-). We found that HP or AR treatment affected the protein levels of MRP2 and P-gp, whereas HP decreased MRP2 and P-gp expression mostly in the T0+ and T6+ conditions, while AR decreased MRP2 in T0- and T6+. Moreover, HY-PDT treatment induced the expression of MRP1. Our data demonstrate that HP or AR treatment in light or dark PDT conditions had an inhibitory effect on the activity of individual membrane transport proteins and significantly decreased CYP3A4 activity in HT-29 cells. We found that HP or AR significantly affected intracellular accumulation of HY in HT-29 colon adenocarcinoma cells. These results suggest that HY, HP and AR might affect the efficiency of anti-cancer drugs, through interaction with membrane transporters and CYP3A4. PMID:27261575

  13. Dye penetrant indications caused by superficial surface defects in 2014 aluminum alloy welds.

    NASA Technical Reports Server (NTRS)

    Hocker, R. G.; Wilson, K. R.

    1971-01-01

    Demonstration that dye penetrant indications on the heat-affected zone of 2014-T6 aluminum GMA weldments are frequently caused by superficial surface conditions and are less than 0.007 in. deep. The following methods are suggested for minimization of these surface defects: stabilization of the arc, application of dc ?GTA' welding procedures, reduction of the caustic etch time, and use of fine grain materials.

  14. Global geographic distribution of Trichinella species and genotypes.

    PubMed

    Feidas, Haralambos; Kouam, Marc K; Kantzoura, Vaia; Theodoropoulos, Georgios

    2014-08-01

    Maximum entropy ecological niche modeling was utilized to describe the global geographic distribution of Trichinella species and genotypes and to assess their invasive risk in new areas other than the ones currently known. Also, space-time scan statistic was utilized to identify global spatiotemporal clusters of infection. A database containing 3209 records for 12 species and genotypes identified at the International Trichinella Reference Center (ITRC) as well as climate, elevation, and land cover data extracted from various databases were used. Ecological niche modeling implemented in the Maxent program indicated new potential ranges for T. spiralis (T1), T. nativa (T2), T. britovi (T3), T. pseudospiralis (T4), T. murrelli (T5), T6, T. papuae (T10), and T. zimbabwensis (T11). The area under the curve values for the test data of the models ranged from 0.901 to 0.998, indicating that the models were very good to excellent. The most important bioclimatic factor in modeling the ranges for T. spiralis (T1), T. nativa (T2), T. britovi (T3), T6, and T. zimbabwensis (T11) was temperature, for T. pseudospiralis (T4) and T. papuae (T10) was precipitation, and for T. murrelli (T5) was land cover. T. spiralis (T1), T. britovi (T3), and T. pseudospiralis (T4) had the same primary land cover which was "Grass Crops". The primary land covers were "Conifer Boreal Forest" for T. nativa (T2), "Cool Fields and Woods" for T. murrelli (T5), "Upland Tundra" for T6, "Tropical Rainforest" for T. papuae (T10), and "Crops and Town" for T. zimbabwensis (T11). The scan statistic analyses revealed the presence of significant spatiotemporal clusters (p<0.05) for T. spiralis (T1), T. nativa (T2), T. britovi (T3), T. pseudospiralis (T4), T. murrelli (T5), T6, and T. nelsoni (T7). No significant clusters were found for T. papuae (T10) and T. zimbabwensis (T11). PMID:24951834

  15. 27 CFR 9.85 - Willow Creek.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... where the 1,000-foot contour line intersects Kirkham Creek (directly north of section 19, T.7 N./R.5E.), beginning in a southerly direction, the boundary line the 1,000-foot contour line to; (1) The point of intersection between the 1,000-foot contour line and the north section line of section 27, T.6N./R.5E.;...

  16. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... point is on the Walla Walla quadrangle map, in T8N/37E, at the point where the 2,000 foot contour line..., Washington (on maps measured in metric units, this elevation is between the 600 and 650 meter contour lines... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near...

  17. 27 CFR 9.85 - Willow Creek.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... where the 1,000-foot contour line intersects Kirkham Creek (directly north of section 19, T.7 N./R.5E.), beginning in a southerly direction, the boundary line the 1,000-foot contour line to; (1) The point of intersection between the 1,000-foot contour line and the north section line of section 27, T.6N./R.5E.;...

  18. 27 CFR 9.85 - Willow Creek.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... where the 1,000-foot contour line intersects Kirkham Creek (directly north of section 19, T.7 N./R.5E.), beginning in a southerly direction, the boundary line the 1,000-foot contour line to; (1) The point of intersection between the 1,000-foot contour line and the north section line of section 27, T.6N./R.5E.;...

  19. 27 CFR 9.85 - Willow Creek.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... where the 1,000-foot contour line intersects Kirkham Creek (directly north of section 19, T.7 N./R.5E.), beginning in a southerly direction, the boundary line the 1,000-foot contour line to; (1) The point of intersection between the 1,000-foot contour line and the north section line of section 27, T.6N./R.5E.;...

  20. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... point is on the Walla Walla quadrangle map, in T8N/37E, at the point where the 2,000 foot contour line..., Washington (on maps measured in metric units, this elevation is between the 600 and 650 meter contour lines... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near...

  1. 27 CFR 9.85 - Willow Creek.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... where the 1,000-foot contour line intersects Kirkham Creek (directly north of section 19, T.7 N./R.5E.), beginning in a southerly direction, the boundary line the 1,000-foot contour line to; (1) The point of intersection between the 1,000-foot contour line and the north section line of section 27, T.6N./R.5E.;...

  2. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... point is on the Walla Walla quadrangle map, in T8N/37E, at the point where the 2,000 foot contour line..., Washington (on maps measured in metric units, this elevation is between the 600 and 650 meter contour lines... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near...

  3. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... point is on the Walla Walla quadrangle map, in T8N/37E, at the point where the 2,000 foot contour line..., Washington (on maps measured in metric units, this elevation is between the 600 and 650 meter contour lines... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near...

  4. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... point is on the Walla Walla quadrangle map, in T8N/37E, at the point where the 2,000 foot contour line..., Washington (on maps measured in metric units, this elevation is between the 600 and 650 meter contour lines... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near...

  5. Paraplegia after thoracotomy for division and suture Patent Ductus Arteriosus (PDA).

    PubMed

    Sayasathid, Jarun; Somboonna, Naraporn; Numchaisiri, Chun

    2006-12-01

    A Thai women, aged 22 years old, came to hospital with Patent Ductus Arteriosis (PDA). Left thoracotomy, with division and suturing PDA, was performed. The second day after operation, she developed paraplegia below umbilical level. The CT-scan detected an extradural hematoma in the spinal cavity from T3-T6. To remove the blood clot, the T spine laminectomy was performed. 6 months after the laminectomy, the patient was able to perform her regular exercise. PMID:17214069

  6. 77 FR 58864 - Public Land Order No. 7801; Withdrawal of Public Lands for Protection of Proposed Expansion of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-24

    ... message or question with the above individual. You will receive a reply during normal business hours...., Secs. 1 and 2; Secs. 11 to 14, inclusive, and 23 to 26, inclusive; Sec. 35. T. 6 N., R. 2 E., Sec. 13; Secs. 23 to 26, inclusive; Sec. 35. T. 4 N., R. 3 E., Sec. 1, lots 1 and 2 of NE\\1/4\\, lots 1 and 2...

  7. Comparison of Immunomodulatory and Anticancer Activities in Different Strains of Tremella fuciformis Berk.

    PubMed

    Han, Chien-Kuo; Chiang, Hsin-Chieh; Lin, Chien-Yin; Tang, Chih-Hsin; Lee, Hsinyu; Huang, Ding-Ding; Zeng, Yu-Ru; Chuang, Tsai-Ni; Huang, Yuan-Li

    2015-01-01

    Tremella fuciformis Berk (TF) is a common edible and medicinal mushroom, and has long been used in food and in Chinese medicine. It possesses anticancer, anti-inflammation, anti-oxidative, and neuroprotective abilities. Since their cultivation is a problem, TFs in Taiwan are primarily imported from China, which has a problem with pesticide residues. Thus, the question of whether the Taiwan cultivated TFs, T1, and T6 showed similar or even better results than TFs from China (CH) was assessed in the present study. The results of the physicochemical tests of these TFs showed that T1 extracted by hot water (T1H) has the highest concentration of polysaccharide; meanwhile, T6 extracted by cold water (T6C) showed the highest amount of protein. Regarding the immune modulatory effects of these TFs, hot water extracts of these TFs augmented significantly the inducible nitric oxide synthetase (iNOS), interleukin (IL)-6, and tumor necrosis factor (TNF)-[Formula: see text] mRNA expression than those of cold water extracts. On the other hand, the cold water extracts of TFs, especially of T1C, obviously suppressed cancer cell survival better than those of hot water extracts. Interestingly, we found that hot water extracts of TFs may augment necrotic cell death, whereas, cold water extracts of TFs induce apoptosis. Furthermore, we also showed that these TFs activate caspase-3 cleavage, up regulate the Bax/Bcl-2 ratio, and decrease MMP-9 expressions in PC-3 cells. Taken together, our results indicated that T1 and T6 strains of TFs showed the similar immune modulatory and anticancer abilities were better than the CH strain of TFs. PMID:26621447

  8. Histone H3 Phosphorylation in GBM: a New Rational to Guide the Use of Kinase Inhibitors in anti-GBM Therapy

    PubMed Central

    Pacaud, Romain; Cheray, Mathilde; Nadaradjane, Arulraj; Vallette, François M.; Cartron, Pierre-François

    2015-01-01

    Histones post-translational modifications (PTMs) are crucial components of diverse processes that modulate chromatin. Among the histones PTMs, the histones phosphorylation appears such crucial since it plays a significant role into DNA repair structure, transcription and chromatin compaction during cell division and apoptosis. However, little is known about the prognostic value of the histone phosphorylation in human cancer. This point could be considerate such as an important gap in anti-cancer therapy since the use of adequate kinase inhibitors could remedy to the aberrant histone phosphorylation associated with a poor prognosis factor. To remedy at this situation, we analyzed the phosphorylation level of histone H3 at the residues T3, T6, S10, S28, Y41 and T45 in a collection of 42 glioblastoma multiformes (GBM). Our data indicated that the high level of pH3T6, pH3S10 and pH3Y41 are signatures associated with a poor prognosis of overall survival (OS) of GBM treated with the "temozolomide and irradiation standard" treatment of GBM (named TMZ+Irad treatment). Our data also showed that these signatures are correlated with the high activity of kinases already described as writers of the pH3T6, pH3S10 and pH3Y41 i.e. the PKC, Aurora-B and JAK2, respectively. Finally, our analysis revealed that the use of Enzastaurin, AZD1152, and AZD1480 abrogated the high level of pH3T6, pH3S10 and pH3Y41 while increasing the sensitivity to the “temozolomide and irradiation”-induced cell death. To conclude, it appears that this work provides biomarkers for patient stratification for a therapy including kinase inhibitors. PMID:25553095

  9. Initial Subdivision of Genesis Early Science Polished Aluminum Collector

    NASA Technical Reports Server (NTRS)

    Allton, J. H.; Stansbery, E. K.; McNamara, K. M.; Meshik, A.; See, T. H.; Bastien, R.

    2005-01-01

    A large surface, about 245 square centimeters, of highly polished aluminum 6061 T6 alloy was attached to the science canister thermal panel for the purpose of collecting solar wind noble gases. The analysis of this collector will be part of the Genesis Early Science results. The pre-launch configuration of the collector is shown. The collector sustained some damage during the recovery impact in Utah, September 8, 2004.

  10. Structure and properties of the C-terminal β-helical domain of VgrG protein from Escherichia coli O157.

    PubMed

    Uchida, Kazuya; Leiman, Petr G; Arisaka, Fumio; Kanamaru, Shuji

    2014-03-01

    The bacterial Type 6 secretion system (T6SS) translocates protein toxins (also called effectors) from the cytosol of a T6SS-carrying cell to a target cell by a syringe-like supramolecular complex resembling a contractile tail of bacteriophages. Valine-glycine repeat protein G (VgrG) proteins, which are the homologues of the gp27-gp5 (gene product) cell puncturing complex of bacteriophage T4, are considered to be located at the attacking tip of the bacterial T6SS apparatus. Here, we over-expressed six VgrG proteins from pathogenic Escherichia coli O157 and CFT073 strains. Purified VgrG1 of E. coli O157 and c3393 of E. coli CFT073 form trimer in solution and are rich in β-structure. We also solved the crystal structure of a trypsin-resistant C-terminal fragment of E. coli O157 VgrG1 (VgrG1C(G561)) at 1.95 Å resolution. VgrG1C(G561) forms a three-stranded antiparallel β-helix which is structurally similar to the β-helix domain of the central spike protein (gp138) of phi92 phage, indicating a possible evolutional relationship. Comparison of four different three-stranded β-helix proteins shows how their amino acid composition determines the protein fold. PMID:24307403

  11. Type VI secretion system sheaths as nanoparticles for antigen display

    PubMed Central

    Del Tordello, Elena; Danilchanka, Olga; McCluskey, Andrew J.; Mekalanos, John J.

    2016-01-01

    The bacterial type 6 secretion system (T6SS) is a dynamic apparatus that translocates proteins between cells by a mechanism analogous to phage tail contraction. T6SS sheaths are cytoplasmic tubular structures composed of stable VipA-VipB (named for ClpV-interacting protein A and B) heterodimers. Here, the structure of the VipA/B sheath was exploited to generate immunogenic multivalent particles for vaccine delivery. Sheaths composed of VipB and VipA fused to an antigen of interest were purified from Vibrio cholerae or Escherichia coli and used for immunization. Sheaths displaying heterologous antigens generated better immune responses against the antigen and different IgG subclasses compared with soluble antigen alone. Moreover, antigen-specific antibodies raised against sheaths presenting Neisseria meningitidis factor H binding protein (fHbp) antigen were functional in a serum bactericidal assay. Our results demonstrate that multivalent nanoparticles based on the T6SS sheath represent a versatile scaffold for vaccine applications. PMID:26929342

  12. Preliminary fracture analysis of the core pressure boundary tube for the Advanced Neutron Source Research Reactor

    SciTech Connect

    Schulz, K.C.; Yahr, G.T.

    1995-08-01

    The outer core pressure boundary tube (CPBT) of the Advanced neutron Source (ANS) reactor being designed at Oak Ridge National Laboratory is currently specified as being composed of 6061-T6 aluminum. ASME Boiler and Pressure Vessel Code fracture analysis rules for nuclear components are based on the use of ferritic steels; the expressions, tables, charts and equations were all developed from tests and analyses conducted for ferritic steels. Because of the nature of the Code, design with thin aluminum requires analytical approaches that do not directly follow the Code. The intent of this report is to present a methodology comparable to the ASME Code for ensuring the prevention of nonductile fracture of the CPBT in the ANS reactor. 6061-T6 aluminum is known to be a relatively brittle material; the linear elastic fracture mechanics (LEFM) approach is utilized to determine allowable flaw sizes for the CPBT. A J-analysis following the procedure developed by the Electric Power Research Institute was conducted as a check; the results matched those for the LEFM analysis for the cases analyzed. Since 6061-T6 is known to embrittle when irradiated, the reduction in K{sub Q} due to irradiation is considered in the analysis. In anticipation of probable requirements regarding maximum allowable flaw size, a survey of nondestructive inspection capabilities is also presented. A discussion of probabilistic fracture mechanics approaches, principally Monte Carlo techniques, is included in this report as an introduction to what quantifying the probability of nonductile failure of the CPBT may entail.

  13. [Lymphoscintigraphy in the study of lymphedema of the arms].

    PubMed

    Carena, M; Aprile, C; Zelaschi, G P; Rossi, G; Paroni, G; Campini, R

    1987-04-01

    The aim of this work has been the study of the mechanism of lymph formation and drainage in the upper limb in patients with monolateral lymphoedema (15 limbs, L) in comparison with the apparently healthy limb (S) as well as with a control group (8 limbs, C). After interstitial injection of 99mTc sulphur micro-colloid, scans were obtained employing a LFOV camera linked to a data processor. Results were expressed as percentage of the id removed from the injection site 1 and 6 hr pi, mean T6%/h it is (T6-T1)/5 and percentage lymph nodes uptake at the same times. Mean T6%/h is significantly different between C and L, but not between L and S, while lymph node uptake at 6 hr shows a significant difference even between C and S. Quantitative lymphoscintigraphy appears to be a feasible indicator of early changes in the lymph pathophysiology and supports the hypothesis that lymphoedema generally arises from a predisposing congenital pathology. PMID:3575807

  14. Comparative Genome Analyses of Serratia marcescens FS14 Reveals Its High Antagonistic Potential

    PubMed Central

    Li, Pengpeng; Kwok, Amy H. Y.; Jiang, Jingwei; Ran, Tingting; Xu, Dongqing; Wang, Weiwu; Leung, Frederick C.

    2015-01-01

    S. marcescens FS14 was isolated from an Atractylodes macrocephala Koidz plant that was infected by Fusarium oxysporum and showed symptoms of root rot. With the completion of the genome sequence of FS14, the first comprehensive comparative-genomic analysis of the Serratia genus was performed. Pan-genome and COG analyses showed that the majority of the conserved core genes are involved in basic cellular functions, while genomic factors such as prophages contribute considerably to genome diversity. Additionally, a Type I restriction-modification system, a Type III secretion system and tellurium resistance genes are found in only some Serratia species. Comparative analysis further identified that S. marcescens FS14 possesses multiple mechanisms for antagonism against other microorganisms, including the production of prodigiosin, bacteriocins, and multi-antibiotic resistant determinants as well as chitinases. The presence of two evolutionarily distinct Type VI secretion systems (T6SSs) in FS14 may provide further competitive advantages for FS14 against other microbes. To our knowledge, this is the first report of comparative analysis on T6SSs in the genus, which identifies four types of T6SSs in Serratia spp.. Competition bioassays of FS14 against the vital plant pathogenic bacterium Ralstonia solanacearum and fungi Fusarium oxysporum and Sclerotinia sclerotiorum were performed to support our genomic analyses, in which FS14 demonstrated high antagonistic activities against both bacterial and fungal phytopathogens. PMID:25856195

  15. Identification of protein secretion systems in bacterial genomes

    PubMed Central

    Abby, Sophie S.; Cury, Jean; Guglielmini, Julien; Néron, Bertrand; Touchon, Marie; Rocha, Eduardo P. C.

    2016-01-01

    Bacteria with two cell membranes (diderms) have evolved complex systems for protein secretion. These systems were extensively studied in some model bacteria, but the characterisation of their diversity has lagged behind due to lack of standard annotation tools. We built online and standalone computational tools to accurately predict protein secretion systems and related appendages in bacteria with LPS-containing outer membranes. They consist of models describing the systems’ components and genetic organization to be used with MacSyFinder to search for T1SS-T6SS, T9SS, flagella, Type IV pili and Tad pili. We identified ~10,000 candidate systems in bacterial genomes, where T1SS and T5SS were by far the most abundant and widespread. All these data are made available in a public database. The recently described T6SSiii and T9SS were restricted to Bacteroidetes, and T6SSii to Francisella. The T2SS, T3SS, and T4SS were frequently encoded in single-copy in one locus, whereas most T1SS were encoded in two loci. The secretion systems of diderm Firmicutes were similar to those found in other diderms. Novel systems may remain to be discovered, since some clades of environmental bacteria lacked all known protein secretion systems. Our models can be fully customized, which should facilitate the identification of novel systems. PMID:26979785

  16. The Effect of Rra on the Microstructure and Properties of a Novel Al-Zn-Mg-Cu-Zr Alloy

    NASA Astrophysics Data System (ADS)

    Li, Xiwu; Xiong, Baiqing; Zhang, Yongan; Zhu, Baohong; Liu, Hongwei; Li, Zhihui

    A novel Al-7.5Zn-1.6Mg-1.4Cu-0.12Zr alloy was subjected to the retrogression and re-ageing (RRA) treatments at a lower range of retrogression temperatures from 170 to 200°C. The effect of RRA on the mechanical properties, electrical conductivity and the microstructure of the alloy has been investigated. The results indicate that an increase in the yield strength of the alloy can be achieved after RRA treatment. With increase of the retrogression temperature, the retrogression time for keeping the strength levels similar to T6 temper decreases rapidly. When submitted to RRA at 170°C for 90-120 min, the alloy can obtain a good performance on both SCC and mechanical strength; the electrical conductivity was above 40%IACS, reaching values typical for T76 condition and the tensile yield strength values were 552-570 MPa which is higher than that of the T6 temper. The microstructure is a very fine distribution of GP zones and η‧ precipitates inside grains, similar to T6 condition and η precipitates on grain boundaries distributed similarly to T7 temper.

  17. Human dendritic cells and macrophages. In situ immunophenotypic definition of subsets that exhibit specific morphologic and microenvironmental characteristics.

    PubMed Central

    Wood, G. S.; Turner, R. R.; Shiurba, R. A.; Eng, L.; Warnke, R. A.

    1985-01-01

    Using a panel of monoclonal antibodies and antisera in situ, the authors have defined subsets of human dendritic cells and macrophages that exhibit specific morphologic and microenvironmental characteristics. All subsets contained cells that reacted with antibodies directed against HLA-A,B,C, HLA-Dr, leukocyte common, Leu-M3, and Leu-3(T4) antigens. R4/23 and anti-S100 defined three major subsets. R4/23+, S100- cells constituted the B-cell-related follicular dendritic cells, which were identified only within the germinal center/mantle microenvironment of lymphoid follicles. R4/23-, S100+ cells constituted the T-cell-related dendritic cell subset. Anti-Leu-6(T6) further subdivided this group into Leu-6(T6)- interdigitating cells within the T-cell microenvironments of lymphoid organs and Leu-6(T6)+ Langerhans cells found predominantly in epithelial microenvironments, especially the skin. R4/23-, S100- cells constituted the nondendritic tissue macrophage subset which was widely distributed, primarily outside of dendritic-cell microenvironments. These data indicate that although dendritic cells and macrophages share several common antigenic features, morphologically and microenvironmentally distinct subsets express distinct immunologic phenotypes. Such data may provide insight into the ontogeny and function of these subsets and constitute a basis for the comparison of normal dendritic cells and macrophages to various histiocytic proliferative disorders. Images Figure 1 Figure 2 p78-c Figure 3 Figure 4 Figure 5 PMID:3985124

  18. Manufacturing of an aluminum alloy mold for micro-hot embossing of polymeric micro-devices

    NASA Astrophysics Data System (ADS)

    Tran, N. K.; Lam, Y. C.; Yue, C. Y.; Tan, M. J.

    2010-05-01

    In micro-hot embossing of polymeric micro-devices, e.g. microfluidic devices, the quality of the mold plays an important role in determining not only the product quality but also the overall production cost. Often the mold is made of silicon, which is brittle and fails after producing a limited number of parts. Metallic molds produced by micro-machining have a much longer life; however, the surface finish of the mold is not ideal for producing polymeric devices that require good surface finish. The metallic glass mold produced by micro-hot embossing with a silicon master is a recent development, which could produce high quality and high strength molds with long life span. However, metallic glasses are rather costly. In an attempt to reduce the production cost of the mold with acceptable quality, strength and life span, we explore here the manufacture of an aluminum alloy (AA6061-T6) mold by hot embossing using a silicon master. Using a set of channels to be produced on the aluminum alloy as the benchmark, we examine the orientation effect of the channels on the AA6061-T6 mold produced by hot embossing. Finally, to examine the effectiveness of the AA6061-T6 mold, it is employed for the hot embossing of polymeric (TOPAS 8007) substrates.

  19. Crystal Structure of Hcp from Acinetobacter baumannii: A Component of the Type VI Secretion System

    PubMed Central

    Ruiz, Federico M.; Santillana, Elena; Spínola-Amilibia, Mercedes; Torreira, Eva; Culebras, Esther; Romero, Antonio

    2015-01-01

    The type VI secretion system (T6SS) is a bacterial macromolecular machine widely distributed in Gram-negative bacteria, which transports effector proteins into eukaryotic host cells or other bacteria. Membrane complexes and a central tubular structure, which resembles the tail of contractile bacteriophages, compose the T6SS. One of the proteins forming this tube is the hemolysin co-regulated protein (Hcp), which acts as virulence factor, as transporter of effectors and as a chaperone. In this study, we present the structure of Hcp from Acinetobacter baumannii, together with functional and oligomerization studies. The structure of this protein exhibits a tight β barrel formed by two β sheets and flanked at one side by a short α-helix. Six Hcp molecules associate to form a donut-shaped hexamer, as observed in both the crystal structure and solution. These results emphasize the importance of this oligomerization state in this family of proteins, despite the low similarity of sequence among them. The structure presented in this study is the first one for a protein forming part of a functional T6SS from A. baumannii. These results will help us to understand the mechanism and function of this secretion system in this opportunistic nosocomial pathogen. PMID:26079269

  20. Prevalence of Trichinella spp. in black bears, grizzly bears, and wolves in the Dehcho Region, Northwest Territories, Canada, including the first report of T. nativa in a grizzly bear from Canada.

    PubMed

    Larter, Nicholas C; Forbes, Lorry B; Elkin, Brett T; Allaire, Danny G

    2011-07-01

    Samples of muscle from 120 black bears (Ursus americanus), 11 grizzly bears (Ursus arctos), and 27 wolves (Canis lupus) collected in the Dehcho Region of the Northwest Territories from 2001 to 2010 were examined for the presence of Trichinella spp. larvae using a pepsin-HCl digestion assay. Trichinella spp. larvae were found in eight of 11 (73%) grizzly bears, 14 of 27 (52%) wolves, and seven of 120 (5.8%) black bears. The average age of positive grizzly bears, black bears, and wolves was 13.5, 9.9, and approximately 4 yr, respectively. Larvae from 11 wolves, six black bears, and seven grizzly bears were genotyped. Six wolves were infected with T. nativa and five with Trichinella T6, four black bears were infected with T. nativa and two with Trichinella T6, and all seven grizzly bears were infected with Trichinella T6 and one of them had a coinfection with T. nativa. This is the first report of T. nativa in a grizzly bear from Canada. Bears have been linked to trichinellosis outbreaks in humans in Canada, and black bears are a subsistence food source for residents of the Dehcho region. In order to assess food safety risk it is important to monitor the prevalence of Trichinella spp. in both species of bear and their cohabiting mammalian food sources. PMID:21719845

  1. Test-retest reliability of EEG spectral parameters during cognitive tasks: II. Coherence.

    PubMed

    Harmony, T; Fernández, T; Rodríguez, M; Reyes, A; Marosi, E; Bernal, J

    1993-02-01

    We analyzed test-retest reliability of EEG coherence during rest and during two cognitive tasks: one verbal, the search for a synonym, and the other consisting of mental mathematical calculations. The experiment was performed twice, with a month's interval between each session. Coherence between all pairwise combinations of the EEG recorded in 15 leads was computed for delta, theta, alpha and beta bands. Comparing the changes observed between sessions for each condition, few significant changes were observed during rest, and the condition which manifests the most changes was calculation. Differences between conditions were observed in the second session in P3-T5, P3-T6, P3-T3, P4-T6, P4-T5, P4-Cz and Cz-T6 delta coherences ordered in a decreasing order from calculation to synonyms to rest. In order to ascertain whether the pattern of coherences across the head in each subject varied in relation to the session and the condition, we computed the correlation coefficients between all coherences values for one condition versus the other condition per band. For all subjects correlation coefficients near unity were observed between conditions in each session. However, correlation coefficients between sessions, even for the same condition, were much lower. We also computed the correlation coefficients for the coherence values between subjects in the same condition separately for each session. Correlation coefficients between subjects were much higher in the second session than in the first one.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8063531

  2. Morphologies of fibroblast cells cultured on surfaces of PHB films implanted by hydroxyl ions.

    PubMed

    Hou, T; Zhang, J Z; Kong, L J; Zhang, X E; Hu, P; Zhang, D M; Li, N

    2006-01-01

    Polyhydroxybutyrate (PHB) films were implanted with 40 keV hydroxyl ions with fluences ranging from 1 x 10(12) to 1 x 10(15) ions/cm2, respectively. The as-implanted PHB films were characterized by scanning electron microscopy (SEM), electron spectroscopy for chemical analysis (ESCA) and water contact angle measurements. The surface structures and properties of the as-implanted PHB films were closely related with hydroxyl ion fluence. They were further investigated by inoculating 3T6 fibroblasts cells on their surfaces. Morphologies of the 3T6 fibroblast cells cultured on surfaces of the as-implanted PHB films were observed by SEM. Characterization of the cultural 3T6 cells was analyzed qualitatively. The preliminary experimental results reveal that the bioactivity of the PHB films modified by hydroxyl ion implantation was improved at different levels, and the fluence of 1 x 10(13) ions/cm2 is optimal for PHB film. PMID:16909942

  3. Whole genome sequencing provides insights into the genetic determinants of invasiveness in Salmonella Dublin.

    PubMed

    Mohammed, M; Cormican, M

    2016-08-01

    Salmonella enterica subsp. enterica serovar Dublin (S. Dublin) is one of the non-typhoidal Salmonella (NTS); however, a relatively high proportion of human infections are associated with invasive disease. We applied whole genome sequencing to representative invasive and non-invasive clinical isolates of S. Dublin to determine the genomic variations among them and to investigate the underlying genetic determinants associated with invasiveness in S. Dublin. Although no particular genomic variation was found to differentiate in invasive and non-invasive isolates four virulence factors were detected within the genome of all isolates including two different type VI secretion systems (T6SS) encoded on two Salmonella pathogenicity islands (SPI), including SPI-6 (T6SSSPI-6) and SPI-19 (T6SSSPI-19), an intact lambdoid prophage (Gifsy-2-like prophage) that contributes significantly to the virulence and pathogenesis of Salmonella serotypes in addition to a virulence plasmid. These four virulence factors may all contribute to the potential of S. Dublin to cause invasive disease in humans. PMID:26996313

  4. Withdrawal of inhaled corticosteroids can be safe in COPD patients at low risk of exacerbation: a real-life study on the appropriateness of treatment in moderate COPD patients (OPTIMO)

    PubMed Central

    2014-01-01

    Background It has been suggested that withdrawal of inhaled corticosteroids (ICS) in COPD patients on maintenance treatment results in deterioration of symptoms, lung function and exacerbations. The aim of this real-life, prospective, multicentric study was to investigate whether withdrawal of ICS in COPD patients at low risk of exacerbation is linked to a deterioration in lung function and symptoms and to a higher frequency of exacerbations. Methods 914 COPD patients, on maintenance therapy with bronchodilators and ICS, FEV1>50% predicted, and <2 exacerbations/year were recruited. Upon decision of the primary physicians, 59% of patients continued their ICS treatment whereas in 41% of patients ICS were withdrawn and regular therapy was continued with long-acting bronchodilators mostly (91% of patients). FEV1, CAT (COPD Assessment Test), and occurrence of exacerbations were measured at the beginning (T0) and at the end (T6) of the 6 months observational period. Results 816 patients (89.3%) concluded the study. FEV1, CAT and exacerbations history were similar in the two groups (ICS and no ICS) at T0 and at T6. We did not observe any deterioration of lung function symptoms, and exacerbation rate between the two groups at T0 and T6. Conclusions We conclude that the withdrawal of ICS, in COPD patients at low risk of exacerbation, can be safe provided that patients are left on maintenance treatment with long-acting bronchodilators. PMID:25005873

  5. Intravitreal Injection of Ozurdex® Implant in Patients with Persistent Diabetic Macular Edema, with Six-Month Follow-Up

    PubMed Central

    Pacella, Fernanda; Ferraresi, Adriana Francesca; Turchetti, Paolo; Lenzi, Tommaso; Giustolisi, Rosalia; Bottone, Andrea; Fameli, Valeria; Romano, Maria Rosaria; Pacella, Elena

    2016-01-01

    AIM To evaluate the efficacy of intravitreal dexamethasone injections in diabetic macular edema (DME). METHODS A 700 μg slow-release intravitreal dexamethasone implant (Ozurdex®) was placed in the vitreal cavity of 17 patients (19 eyes) affected with persistent DME. Best corrected visual acuity (BCVA) was assessed through Early Treatment Diabetic Retinopathy Study (ETDRS). Central macular thickness (CMT) was measured by spectral-domain optical coherence tomography. BCVA and CMT examinations were carried out at baseline (T0) and repeated after three days, one month (T1), three months (T3), four months (T4), and six months (T6) post injection. RESULTS Dexamethasone implant induced an improvement in ETDRS at T1, T3, T4, and T6 post injection. CMT was reduced at T1, T3, and T4, while at T6, CMT values were not statistically different from baseline. No complications were observed during the follow-up. CONCLUSION Our data suggest that dexamethasone implant is effective in reducing DME symptoms within a six-month frame. PMID:27147895

  6. A Burkholderia Type VI Effector Deamidates Rho GTPases to Activate the Pyrin Inflammasome and Trigger Inflammation.

    PubMed

    Aubert, Daniel F; Xu, Hao; Yang, Jieling; Shi, Xuyan; Gao, Wenqing; Li, Lin; Bisaro, Fabiana; Chen, She; Valvano, Miguel A; Shao, Feng

    2016-05-11

    Burkholderia cenocepacia is an opportunistic pathogen of the cystic fibrosis lung that elicits a strong inflammatory response. B. cenocepacia employs a type VI secretion system (T6SS) to survive in macrophages by disarming Rho-type GTPases, causing actin cytoskeletal defects. Here, we identified TecA, a non-VgrG T6SS effector responsible for actin disruption. TecA and other bacterial homologs bear a cysteine protease-like catalytic triad, which inactivates Rho GTPases by deamidating a conserved asparagine in the GTPase switch-I region. RhoA deamidation induces caspase-1 inflammasome activation, which is mediated by the familial Mediterranean fever disease protein Pyrin. In mouse infection, the deamidase activity of TecA is necessary and sufficient for B. cenocepacia-triggered lung inflammation and also protects mice from lethal B. cenocepacia infection. Therefore, Burkholderia TecA is a T6SS effector that modifies a eukaryotic target through an asparagine deamidase activity, which in turn elicits host cell death and inflammation through activation of the Pyrin inflammasome. PMID:27133449

  7. Involvement of type VI secretion system in secretion of iron chelator pyoverdine in Pseudomonas taiwanensis

    PubMed Central

    Chen, Wen-Jen; Kuo, Tzu-Yen; Hsieh, Feng-Chia; Chen, Pi-Yu; Wang, Chang-Sheng; Shih, Yu-Ling; Lai, Ying-Mi; Liu, Je-Ruei; Yang, Yu-Liang; Shih, Ming-Che

    2016-01-01

    Rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive rice diseases worldwide. Therefore, in addition to breeding disease-resistant rice cultivars, it is desirable to develop effective biocontrol agents against Xoo. Here, we report that a soil bacterium Pseudomonas taiwanensis displayed strong antagonistic activity against Xoo. Using matrix-assisted laser desorption/ionization imaging mass spectrometry, we identified an iron chelator, pyoverdine, secreted by P. taiwanensis that could inhibit the growth of Xoo. Through Tn5 mutagenesis of P. taiwanensis, we showed that mutations in genes that encode components of the type VI secretion system (T6SS) as well as biosynthesis and maturation of pyoverdine resulted in reduced toxicity against Xoo. Our results indicated that T6SS is involved in the secretion of endogenous pyoverdine. Mutations in T6SS component genes affected the secretion of mature pyoverdine from the periplasmic space into the extracellular medium after pyoverdine precursor is transferred to the periplasm by the inner membrane transporter PvdE. In addition, we also showed that other export systems, i.e., the PvdRT-OpmQ and MexAB-OprM efflux systems (for which there have been previous suggestions of involvement) and the type II secretion system (T2SS), are not involved in pyoverdine secretion. PMID:27605490

  8. New insights into virulence mechanisms of rice pathogen Acidovorax avenae subsp. avenae strain RS-1 following exposure to ß-lactam antibiotics

    PubMed Central

    Li, Bin; Ge, Mengyu; Zhang, Yang; Wang, Li; Ibrahim, Muhammad; Wang, Yanli; Sun, Guochang; Chen, Gongyou

    2016-01-01

    Recent research has shown that pathogen virulence can be altered by exposure to antibiotics, even when the growth rate is unaffected. Investigating this phenomenon provides new insights into understanding the virulence mechanisms of bacterial pathogens. This study investigates the phenotypic and transcriptomic responses of the rice pathogenic bacterium Acidovorax avenae subsp. avenae (Aaa) strain RS-1 to ß-lactam antibiotics especially Ampicillin (Amp). Our results indicate that exposure to Amp does not influence bacterial growth and biofilm formation, but alters the virulence, colonization capacity, composition of extracellular polymeric substances and secretion of Type VI secretion system (T6SS) effector Hcp. This attenuation in virulence is linked to unique or differential expression of known virulence-associated genes based on genome-wide transcriptomic analysis. The reliability of expression data generated by RNA-Seq was verified with quantitative real-time PCR of 21 selected T6SS genes, where significant down-regulation in expression of hcp gene, corresponding to the reduction in secretion of Hcp, was observed under exposure to Amp. Hcp is highlighted as a potential target for Amp, with similar changes observed in virulence-associated phenotypes between exposure to Amp and mutation of hcp gene. In addition, Hcp secretion is reduced in knockout mutants of 4 differentially expressed T6SS genes. PMID:26915352

  9. Performance Verification of Impact Machines for Testing Plastics

    PubMed Central

    Siewert, T. A.; Vigliotti, D. P.; Dirling, L. B.; McCowan, C. N.

    1999-01-01

    Valid comparison of impact test energies reported by various organizations and over time depends on consistent performance of impact test machines. This paper investigates the influence of various specimen and test parameters on impact energies in the 1 J to 2 J range for both Charpy V-notch and Izod procedures, leading toward the identification of a suitable material for use in a program to verify machine performance. We investigated the influences on the absorbed energy of machine design, test material, specimen cross sectional area, and machine energy range. For comparison to published round robin data on common plastics, this study used some common metallic alloys, including those used in the international verification program for metals impact machines and in informal calibration programs of tensile machines. The alloys that were evaluated include AISI type 4340 steel, and five aluminum alloys: 2014-T6, 2024-T351, 2219-T87, 6061-T6, and 7075-T6. We found that certain metallic alloys have coefficients of variation comparable to those of the best plastics that are reported in the literature. Also, we found that the differences in absorbed energy between two designs of machines are smaller than the differences that can be attributed to the specimens alone.

  10. Disruption in Candida albicans of the TPS2 gene encoding trehalose-6-phosphate phosphatase affects cell integrity and decreases infectivity.

    PubMed

    Zaragoza, Oscar; de Virgilio, Claudio; Pontón, José; Gancedo, Carlos

    2002-05-01

    The gene CaTPS2 encoding trehalose-6-phosphate (T6P) phosphatase from Candida albicans has been cloned and disrupted in this organism. The Catps2/Catps2 mutant did not accumulate trehalose but accumulated high levels of T6P. Disruption of the two copies of the CaTPS2 gene did not abolish growth even at 42 degrees C, but decreased the growth rate. In the stationary phase, the Catps2/Catps2 mutant aggregated, more than 50% of its cells became permeable to propidium iodide and a large amount of protein was found in the culture medium. Aggregation occurred only at pH values higher than 7 and was avoided by osmoprotectants; it was never observed during the exponential phase of growth. The mutant formed colonies with a smooth border on Spider medium. Mice inoculated with 1.5 x 10(6) c.f.u. of wild-type cells died after 8 days, while 80% of those inoculated with the same number of c.f.u. of the Catps2/Catps2 mutant survived for at least 1 month. Reintroduction of the wild-type CaTPS2 gene in the Catps2/Catps2 mutant abolished the phenotypes described. It is hypothesized that the accumulation of T6P interferes with the assembly of a normal cell wall. PMID:11988502

  11. Intracellular glutathione depletion by oridonin leads to apoptosis in hepatic stellate cells.

    PubMed

    Kuo, Liang-Mou; Kuo, Chan-Yen; Lin, Chen-Yu; Hung, Min-Fa; Shen, Jiann-Jong; Hwang, Tsong-Long

    2014-01-01

    Proliferation of hepatic stellate cells (HSCs) plays a key role in the pathogenesis of liver fibrosis. Induction of HSC apoptosis by natural products is considered an effective strategy for treating liver fibrosis. Herein, the apoptotic effects of 7,20-epoxy-ent-kaurane (oridonin), a diterpenoid isolated from Rabdosia rubescens, and its underlying mechanisms were investigated in rat HSC cell line, HSC-T6. We found that oridonin inhibited cell viability of HSC-T6 in a concentration-dependent manner. Oridonin induced a reduction in mitochondrial membrane potential and increases in caspase 3 activation, subG1 phase, and DNA fragmentation. These apoptotic effects of oridonin were completely reversed by thiol antioxidants, N-acetylcysteine (NAC) and glutathione monoethyl ester. Moreover, oridonin increased production of reactive oxygen species (ROS), which was also inhibited by NAC. Significantly, oridonin reduced intracellular glutathione (GSH) level in a concentration- and time-dependent fashion. Additionally, oridonin induced phosphorylations of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK). NAC prevented the activation of MAPKs in oridonin-induced cells. However, selective inhibitors of MAPKs failed to alter oridonin-induced cell death. In summary, these results demonstrate that induction of apoptosis in HSC-T6 by oridonin is associated with a decrease in cellular GSH level and increase in ROS production. PMID:24647034

  12. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-07-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  13. A type VI secretion-related pathway in Bacteroidetes mediates interbacterial antagonism

    PubMed Central

    Russell, A.B.; Wexler, A.G.; Harding, B.N.; Whitney, J.C.; Bohn, A.J.; Goo, Y.A.; Tran, B.Q.; Barry, N.A.; Zheng, H.; Peterson, S.B.; Chou, S.; Gonen, T.; Goodlett, D.R.; Goodman, A.L.; Mougous, J.D.

    2014-01-01

    Summary Bacteroidetes are a phylum of Gram-negative bacteria abundant in mammalian-associated polymicrobial communities, where they impact digestion, immunity and resistance to infection. Despite extensive competition at high cell density that occurs in these settings, cell contact-dependent mechanisms of interbacterial antagonism, such as the type VI secretion system (T6SS), have not been defined in this group of organisms. Herein we report the bioinformatic and functional characterization of a T6SS-like pathway in diverse Bacteroidetes. Using prominent human gut commensal and soil-associated species, we demonstrate that these systems localize dynamically within the cell, export antibacterial proteins, and target competitor bacteria. The Bacteroidetes system is a distinct pathway with marked differences in gene content and high evolutionary divergence from the canonical T6S pathway. Our findings offer a potential molecular explanation for the abundance of Bacteroidetes in polymicrobial environments, the observed stability of Bacteroidetes in healthy humans, and the barrier presented by the microbiota against pathogens. PMID:25070807

  14. The translocation (6;9), associated with a specific subtype of acute myeloid leukemia, results in the fusion of two genes, dek and can, and the expression of a chimeric, leukemia-specific dek-can mRNA.

    PubMed Central

    von Lindern, M; Fornerod, M; van Baal, S; Jaegle, M; de Wit, T; Buijs, A; Grosveld, G

    1992-01-01

    The translocation (6;9) is associated with a specific subtype of acute myeloid leukemia (AML). Previously, it was found that breakpoints on chromosome 9 are clustered in one of the introns of a large gene named Cain (can). cDNA probes derived from the 3' part of can detect an aberrant, leukemia-specific 5.5-kb transcript in bone marrow cells from t(6;9) AML patients. cDNA cloning of this mRNA revealed that it is a fusion of sequences encoded on chromosome 6 and 3' can. A novel gene on chromosome 6 which was named dek was isolated. In dek the t(6;9) breakpoints also occur in one intron. As a result the dek-can fusion gene, present in t(6;9) AML, encodes an invariable dek-can transcript. Sequence analysis of the dek-can cDNA showed that dek and can are merged without disruption of the original open reading frames and therefore the fusion mRNA encodes a chimeric DEK-CAN protein of 165 kDa. The predicted DEK and CAN proteins have molecular masses of 43 and 220 kDa, respectively. Sequence comparison with the EMBL data base failed to show consistent homology with any known protein sequences. Images PMID:1549122

  15. Genetic Architecture of Abdominal Pigmentation in Drosophila melanogaster

    PubMed Central

    Dembeck, Lauren M.; Huang, Wen; Magwire, Michael M.; Lawrence, Faye; Lyman, Richard F.; Mackay, Trudy F. C.

    2015-01-01

    Pigmentation varies within and between species and is often adaptive. The amount of pigmentation on the abdomen of Drosophila melanogaster is a relatively simple morphological trait, which serves as a model for mapping the genetic basis of variation in complex phenotypes. Here, we assessed natural variation in female abdominal pigmentation in 175 sequenced inbred lines of the Drosophila melanogaster Genetic Reference Panel, derived from the Raleigh, NC population. We quantified the proportion of melanization on the two most posterior abdominal segments, tergites 5 and 6 (T5, T6). We found significant genetic variation in the proportion of melanization and high broad-sense heritabilities for each tergite. Genome-wide association studies identified over 150 DNA variants associated with the proportion of melanization on T5 (84), T6 (34), and the difference between T5 and T6 (35). Several of the top variants associated with variation in pigmentation are in tan, ebony, and bric-a-brac1, genes known to affect D. melanogaster abdominal pigmentation. Mutational analyses and targeted RNAi-knockdown showed that 17 out of 28 (61%) novel candidate genes implicated by the genome-wide association study affected abdominal pigmentation. Several of these genes are involved in developmental and regulatory pathways, chitin production, cuticle structure, and vesicle formation and transport. These findings show that genetic variation may affect multiple steps in pathways involved in tergite development and melanization. Variation in these novel candidates may serve as targets for adaptive evolution and sexual selection in D. melanogaster. PMID:25933381

  16. Involvement of type VI secretion system in secretion of iron chelator pyoverdine in Pseudomonas taiwanensis.

    PubMed

    Chen, Wen-Jen; Kuo, Tzu-Yen; Hsieh, Feng-Chia; Chen, Pi-Yu; Wang, Chang-Sheng; Shih, Yu-Ling; Lai, Ying-Mi; Liu, Je-Ruei; Yang, Yu-Liang; Shih, Ming-Che

    2016-01-01

    Rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive rice diseases worldwide. Therefore, in addition to breeding disease-resistant rice cultivars, it is desirable to develop effective biocontrol agents against Xoo. Here, we report that a soil bacterium Pseudomonas taiwanensis displayed strong antagonistic activity against Xoo. Using matrix-assisted laser desorption/ionization imaging mass spectrometry, we identified an iron chelator, pyoverdine, secreted by P. taiwanensis that could inhibit the growth of Xoo. Through Tn5 mutagenesis of P. taiwanensis, we showed that mutations in genes that encode components of the type VI secretion system (T6SS) as well as biosynthesis and maturation of pyoverdine resulted in reduced toxicity against Xoo. Our results indicated that T6SS is involved in the secretion of endogenous pyoverdine. Mutations in T6SS component genes affected the secretion of mature pyoverdine from the periplasmic space into the extracellular medium after pyoverdine precursor is transferred to the periplasm by the inner membrane transporter PvdE. In addition, we also showed that other export systems, i.e., the PvdRT-OpmQ and MexAB-OprM efflux systems (for which there have been previous suggestions of involvement) and the type II secretion system (T2SS), are not involved in pyoverdine secretion. PMID:27605490

  17. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-06-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  18. Transcriptome analysis of Acidovorax avenae subsp. avenae cultivated in vivo and co-culture with Burkholderia seminalis.

    PubMed

    Li, Bin; Ibrahim, Muhammad; Ge, Mengyu; Cui, Zhouqi; Sun, Guochang; Xu, Fei; Kube, Michael

    2014-01-01

    Response of bacterial pathogen to environmental bacteria and its host is critical for understanding of microbial adaption and pathogenesis. Here, we used RNA-Seq to comprehensively and quantitatively assess the transcriptional response of Acidovorax avenae subsp. avenae strain RS-1 cultivated in vitro, in vivo and in co-culture with rice rhizobacterium Burkholderia seminalis R456. Results revealed a slight response to other bacteria, but a strong response to host. In particular, a large number of virulence associated genes encoding Type I to VI secretion systems, 118 putative non-coding RNAs, and 7 genomic islands (GIs) were differentially expressed in vivo based on comparative genomic and transcriptomic analyses. Furthermore, the loss of virulence for knockout mutants of 11 differentially expressed T6SS genes emphasized the importance of these genes in bacterial pathogenicity. In addition, the reliability of expression data obtained by RNA-Seq was supported by quantitative real-time PCR of the 25 selected T6SS genes. Overall, this study highlighted the role of differentially expressed genes in elucidating bacterial pathogenesis based on combined analysis of RNA-Seq data and knockout of T6SS genes. PMID:25027476

  19. T(lys), a newly identified Sulfolobus spindle-shaped virus 1 transcript expressed in the lysogenic state, encodes a DNA-binding protein interacting at the promoters of the early genes.

    PubMed

    Fusco, Salvatore; She, Qunxin; Bartolucci, Simonetta; Contursi, Patrizia

    2013-05-01

    While studying the gene expression of the Sulfolobus spindle-shaped virus 1 (SSV1) in Sulfolobus solfataricus lysogenic cells, a novel viral transcript (T(lys)) was identified. Transcriptional analysis revealed that T(lys) is expressed only in the absence of UV irradiation and is downregulated during the growth of the lysogenic host. The correponding gene f55 lies between two transcriptional units (T6 and T(ind)) that are upregulated upon UV irradiation. The open reading frame f55 encodes a 6.3-kDa protein which shows sequence identity with negative regulators that fold into the ribbon-helix-helix DNA-binding motif. DNA-binding assays demonstrated that the recombinant F55, purified from Escherichia coli, is indeed a putative transcription factor able to recognize site specifically target sequences in the promoters of the early induced T5, T6, and T(ind) transcripts, as well as of its own promoter. Binding sites of F55 are included within a tandem-repeated sequence overlapping the transcription start sites and/or the B recognition element of the pertinent genes. The strongest binding was observed with the promoters of T5 and T6, and an apparent cooperativity in binding was observed with the T(ind) promoter. Taking together the transcriptional analysis data and the biochemical evidences, we surmise that the protein F55 is involved in the regulation of the lysogenic state of SSV1. PMID:23514883

  20. Trehalose-6-phosphate synthesis controls yeast gluconeogenesis downstream and independent of SNF1.

    PubMed

    Deroover, Sofie; Ghillebert, Ruben; Broeckx, Tom; Winderickx, Joris; Rolland, Filip

    2016-06-01

    Trehalose-6-P (T6P), an intermediate of trehalose biosynthesis, was identified as an important regulator of yeast sugar metabolism and signaling. tps1Δ mutants, deficient in T6P synthesis (TPS), are unable to grow on rapidly fermentable medium with uncontrolled influx in glycolysis, depletion of ATP and accumulation of sugar phosphates. However, the exact molecular mechanisms involved are not fully understood. We show that SNF1 deletion restores the tps1Δ growth defect on glucose, suggesting that lack of TPS hampers inactivation of SNF1 or SNF1-regulated processes. In addition to alternative, non-fermentable carbon metabolism, SNF1 controls two major processes: respiration and gluconeogenesis. The tps1Δ defect appears to be specifically associated with deficient inhibition of gluconeogenesis, indicating more downstream effects. Consistently, Snf1 dephosphorylation and inactivation on glucose medium are not affected, as confirmed with an in vivo Snf1 activity reporter. Detailed analysis shows that gluconeogenic Pck1 and Fbp1 expression, protein levels and activity are not repressed upon glucose addition to tps1Δ cells, suggesting a link between the metabolic defect and persistent gluconeogenesis. While SNF1 is essential for induction of gluconeogenesis, T6P/TPS is required for inactivation of gluconeogenesis in the presence of glucose, downstream and independent of SNF1 activity and the Cat8 and Sip4 transcription factors. PMID:27189362

  1. Performance verification of impact machines for testing plastics

    SciTech Connect

    Siewert, T.A.; Vigliotti, D.P.; Dirling, L.B.; McCowan, C.N.

    1999-12-01

    Valid comparison of impact test energies reported by various organizations and over time depends on consistent performance of impact test machines. This paper investigates the influence of various specimen and test parameters on impact energies in the 1 J to 2 J range for both Charpy V-notch and Izod procedures, leading toward the identification of a suitable material for use in a program to verify machine performance. The authors investigated the influences on the absorbed energy of machine design, test material, specimen cross sectional area, and machine energy range. For comparison to published round robin data on common plastics, this study used some common metallic alloys, including those used in the international verification program for metals impact machines and in informal calibration programs of tensile machines. The alloys that were evaluated include AISI type 4340 steel, and five aluminum alloys: 2014-T6, 2024-T351, 2219-T87, 6061-T6, and 7075-T6. They found that certain metallic alloys have coefficients of variation comparable to those of the best plastics that are reported in the literature. Also, they found that the differences in absorbed energy between two designs of machines are smaller than the differences that can be attributed to the specimens alone.

  2. Chromatin condensation and recruitment of PHD finger proteins to histone H3K4me3 are mutually exclusive.

    PubMed

    Gatchalian, Jovylyn; Gallardo, Carmen Mora; Shinsky, Stephen A; Ospina, Ruben Rosas; Liendo, Andrea Mansilla; Krajewski, Krzysztof; Klein, Brianna J; Andrews, Forest H; Strahl, Brian D; M van Wely, Karel H; Kutateladze, Tatiana G

    2016-07-27

    Histone post-translational modifications, and specific combinations they create, mediate a wide range of nuclear events. However, the mechanistic bases for recognition of these combinations have not been elucidated. Here, we characterize crosstalk between H3T3 and H3T6 phosphorylation, occurring in mitosis, and H3K4me3, a mark associated with active transcription. We detail the molecular mechanisms by which H3T3ph/K4me3/T6ph switches mediate activities of H3K4me3-binding proteins, including those containing plant homeodomain (PHD) and double Tudor reader domains. Our results derived from nuclear magnetic resonance chemical shift perturbation analysis, orthogonal binding assays and cell fluorescence microscopy studies reveal a strong anti-correlation between histone H3T3/T6 phosphorylation and retention of PHD finger proteins in chromatin during mitosis. Together, our findings uncover the mechanistic rules of chromatin engagement for H3K4me3-specific readers during cell division. PMID:27016734

  3. The outcome of combining home based and clinic based amblyopia therapy among preschool children.

    PubMed

    Rokiah, O; Knight, V F; Duratul, A H

    2013-06-01

    This study determined the outcome of combining home based and clinic based amblyopia therapy among preschool children. A total of 479 preschool children were randomly selected for vision screening. Amblyopic therapy was prescribed to children whose visual acuity (VA) could not be improved to <0.1 LogMAR after a 6 week adaptation period with glasses. Intensive near work activities were conducted daily at home for 12 weeks, monitored by parents while weekly therapy was conducted at the optometry clinic by an optometrist. Six preschool children were diagnosed with refractive amblyopia, spherical equivalent (SE) was -11.25D to +0.75D. Significant improvement was found in the VA of right eye, t(6) = 3.07, left eye t(6) = 3.07 and both eyes t(6) = 3.42) p<0.05, at the end of the 12 week therapy. Combining home based and clinic based amblyopia therapy among preschool children showed a positive improvement in VA after 12 weeks of therapy. PMID:23749015

  4. Effects of penehyclidine hydrochloride in small intestinal damage caused by limb ischemia-reperfusion

    PubMed Central

    Zhang, Yan; Leng, Yu-Fang; Xue, Xing; Zhang, Yue; Wang, Tao; Kang, Yu-Qing

    2011-01-01

    AIM: To investigate the protective effect of penehyclidine hydrochloride post-conditioning in the damage to the barrier function of the small intestinal mucosa caused by limb ischemia-reperfusion (LIR) injury. METHODS: Male Wistar rats were randomly divided into three groups (36 rats each): the sham-operation group (group S), lower limb ischemia-reperfusion group (group LIR), and penehyclidine hydrochloride post-conditioning group (group PHC). Each group was divided into subgroups (n = 6 in each group) according to ischemic-reperfusion time, i.e. immediately 0 h (T1), 1 h (T2), 3 h (T3), 6 h (T4), 12 h (T5), and 24 h (T6). Bilateral hind-limb ischemia was induced by rubber band application proximal to the level of the greater trochanter for 3 h. In group PHC, 0.15 mg/kg of penehyclidine hydrochloride was injected into the tail vein immediately after 3 h of bilateral hind-limb ischemia. The designated rats were sacrificed at different time-points of reperfusion; diamine oxidase (DAO), superoxide dismutase (SOD) activity, myeloperoxidase (MPO) of small intestinal tissue, plasma endotoxin, DAO, tumor necrosis factor-α (TNF-α), and interleukin (IL)-10 in serum were detected in the rats. RESULTS: The pathological changes in the small intestine were observed under light microscope. The levels of MPO, endotoxin, serum DAO, and IL-10 at T1-T6, and TNF-α level at T1-T4 increased in groups LIR and PHC (P < 0.05) compared with those in group S, but tissue DAO and SOD activity at T1-T6 decreased (P < 0.05). In group PHC, the tissue DAO and SOD activity at T2-T6, and IL-10 at T2-T5 increased to higher levels than those in group LIR (P < 0.05); however, the levels of MPO, endotoxin, and DAO in the blood at T2-T6, and TNF-α at T2 and T4 decreased (P < 0.05). CONCLUSION: Penehyclidine hydrochloride post-conditioning may reduce the permeability of the small intestines after LIR. Its protection mechanisms may be related to inhibiting oxygen free radicals and inflammatory

  5. miR-181b Promotes hepatic stellate cells proliferation by targeting p27 and is elevated in the serum of cirrhosis patients

    SciTech Connect

    Wang, Baocan; Li, Wenxi; Guo, Kun; Xiao, Yongtao; Wang, Yuqin; Fan, Jiangao

    2012-04-27

    Highlights: Black-Right-Pointing-Pointer miR-181a and miR-181b, especially, miR-181b could be induced by transforming growth factor-beta 1 (TGF-{beta}1) in hepatic stellate cells. Black-Right-Pointing-Pointer miR-181b could promote HSC-T6 cell proliferation by directly targeting the negative cell regulator-p27 in HSC-T6 cell. Black-Right-Pointing-Pointer miR-181b was identified as potential serum diagnostic marker for liver cirrhosis patients. -- Abstract: MicroRNAs, as a kind of negative gene regulators, were demonstrated to be involved in many types of diseases. In this study, we found that transforming growth factor-beta 1 could induce the expression of miR-181a and miR-181b, and miR-181b increased in the much higher folds than miR-181a. Because of the important role of transforming growth factor-beta 1 in HSC activation and liver cirrhosis, we investigate the effect of miR-181a and miR-181b on HSC proliferation. The results showed that miR-181b could promote HSC-T6 cell proliferation by regulating cell cycle. Further study showed p27, the cell cycle regulator, was the direct target of miR-181b in HSC-T6 cell. But miR-181a had no effects on HSC-T6 cell proliferation and cell cycle, and did not target p27. Interestingly, miR-181b is elevated significantly in serum of liver cirrhosis cases comparing to that of normal persons, whereas miR-181a expression was in the similar level with that of normal persons. These results suggested that miR-181b could be induced by TGF-{beta}1 and promote the growth of HSCs by directly targeting p27. The elevation of miR-181b in serum suggested that it may be potential diagnostic biomarkers for cirrhosis. As for miR-181a, it may work in TGF-{beta}1 pathway by a currently unknown mechanism.

  6. Chromium-free conversion coatings based on inorganic salts (Zr/Ti/Mn/Mo) for aluminum alloys used in aircraft applications

    NASA Astrophysics Data System (ADS)

    Santa Coloma, P.; Izagirre, U.; Belaustegi, Y.; Jorcin, J. B.; Cano, F. J.; Lapeña, N.

    2015-08-01

    Novel chromium-free conversion coatings based on Zr/Ti/Mn/Mo compounds were developed at a pilot scale to improve the corrosion resistance of the AA2024-T3 and AA7075-T6 aluminum alloys for aircraft applications. The influence of the presence of Zr and Ti in the Zr/Ti/Mn/Mo conversion bath's formulation on the corrosion resistance of the coated alloys was investigated. The corrosion resistance provided by the conversion coatings was evaluated by salt spray exposure and potentiodynamic sweeps. Optical and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and atomic force microscopy (AFM) operating in the Kelvin Probe mode (SKPFM) were used to provide microstructural information of the coated samples that achieved the best results in the corrosion tests. The salt spray test evidenced the higher corrosion resistance of the coated samples compared to the bare surfaces for both alloys. The potentiodynamic tests showed that the corrosion current density decreased for coated AA7075-T6 and AA2024-T3 alloys, which indicated an obvious improvement of the corrosion resistance with all the processes for both alloys. Although the corrosion resistance of the coated samples appeared to be higher for the alloy AA7075-T6 than for the alloy AA2024-T3, both alloys achieved the best corrosion protection with the coatings deposited from conversion bath formulations containing no titanium salts. The microscopy analysis on the coated AA7075-T6 samples revealed that a local deposition of Zr compounds and, possibly, an oxidation process occurred in the vicinity of the alloy's intermetallic particles. The amount of the Zr deposits at these locations increased with coating's formulations without Ti, which provided the best corrosion resistance. The Cr-free conversion coatings developed in this study for the AA7075-T6 and AA2024-T3 alloys do not meet yet the strict requirements of the aircraft industry. However, they significantly improved the corrosion

  7. The Madagascar hissing cockroach as a novel surrogate host for Burkholderia pseudomallei, B. mallei and B. thailandensis

    PubMed Central

    2012-01-01

    Background Burkholderia pseudomallei and Burkholderia mallei are gram-negative pathogens responsible for the diseases melioidosis and glanders, respectively. Both species cause disease in humans and animals and have been designated as category B select agents by the Centers for Disease Control and Prevention (CDC). Burkholderia thailandensis is a closely related bacterium that is generally considered avirulent for humans. While it can cause disease in rodents, the B. thailandensis 50% lethal dose (LD50) is typically ≥ 104-fold higher than the B. pseudomallei and B. mallei LD50 in mammalian models of infection. Here we describe an alternative to mammalian hosts in the study of virulence and host-pathogen interactions of these Burkholderia species. Results Madagascar hissing cockroaches (MH cockroaches) possess a number of qualities that make them desirable for use as a surrogate host, including ease of breeding, ease of handling, a competent innate immune system, and the ability to survive at 37°C. MH cockroaches were highly susceptible to infection with B. pseudomallei, B. mallei and B. thailandensis and the LD50 was <10 colony-forming units (cfu) for all three species. In comparison, the LD50 for Escherichia coli in MH cockroaches was >105 cfu. B. pseudomallei, B. mallei, and B. thailandensis cluster 1 type VI secretion system (T6SS-1) mutants were all attenuated in MH cockroaches, which is consistent with previous virulence studies conducted in rodents. B. pseudomallei mutants deficient in the other five T6SS gene clusters, T6SS-2 through T6SS-6, were virulent in both MH cockroaches and hamsters. Hemocytes obtained from MH cockroaches infected with B. pseudomallei harbored numerous intracellular bacteria, suggesting that this facultative intracellular pathogen can survive and replicate inside of MH cockroach phagocytic cells. The hemolymph extracted from these MH cockroaches also contained multinuclear giant cells (MNGCs) with intracellular B

  8. T346Hunter: A Novel Web-Based Tool for the Prediction of Type III, Type IV and Type VI Secretion Systems in Bacterial Genomes

    PubMed Central

    Martínez-García, Pedro Manuel; Ramos, Cayo; Rodríguez-Palenzuela, Pablo

    2015-01-01

    T346Hunter (Type Three, Four and Six secretion system Hunter) is a web-based tool for the identification and localisation of type III, type IV and type VI secretion systems (T3SS, T4SS and T6SS, respectively) clusters in bacterial genomes. Non-flagellar T3SS (NF-T3SS) and T6SS are complex molecular machines that deliver effector proteins from bacterial cells into the environment or into other eukaryotic or prokaryotic cells, with significant implications for pathogenesis of the strains encoding them. Meanwhile, T4SS is a more functionally diverse system, which is involved in not only effector translocation but also conjugation and DNA uptake/release. Development of control strategies against bacterial-mediated diseases requires genomic identification of the virulence arsenal of pathogenic bacteria, with T3SS, T4SS and T6SS being major determinants in this regard. Therefore, computational methods for systematic identification of these specialised machines are of particular interest. With the aim of facilitating this task, T346Hunter provides a user-friendly web-based tool for the prediction of T3SS, T4SS and T6SS clusters in newly sequenced bacterial genomes. After inspection of the available scientific literature, we constructed a database of hidden Markov model (HMM) protein profiles and sequences representing the various components of T3SS, T4SS and T6SS. T346Hunter performs searches of such a database against user-supplied bacterial sequences and localises enriched regions in any of these three types of secretion systems. Moreover, through the T346Hunter server, users can visualise the predicted clusters obtained for approximately 1700 bacterial chromosomes and plasmids. T346Hunter offers great help to researchers in advancing their understanding of the biological mechanisms in which these sophisticated molecular machines are involved. T346Hunter is freely available at http://bacterial-virulence-factors.cbgp.upm.es/T346Hunter. PMID:25867189

  9. Overexpression of pim-3 and protective role in lipopolysaccharide-stimulated hepatic stellate cells

    PubMed Central

    Liu, Lin-Hua; Lai, Qi-Nan; Chen, Jian-Yong; Zhang, Ji-Xiang; Cheng, Bin

    2015-01-01

    AIM: To investigate pim-3 expression in hepatic stellate cells (HSCs) stimulated by lipopolysaccharide (LPS), and its protective effect on HSCs. METHODS: Rat HSC-T6 cells were stimulated by LPS. The effect of LPS on proliferation and apoptosis of HSC-T6 cells was investigated by methyl thiazoyltetrazolium (MTT) assay and flow cytometry after annexin V-fluorescein isothiocyanate/propidium iodide double staining. pim-3 mRNA and protein were detected by reverse transcriptase polymerase chain reaction and Western blotting at 48 h when HSC-T6 cells were stimulated with 1 μg/mL LPS for 0, 3, 6, 12, 24 and 48 h. The cells without stimulation served as controls. To study the effect of pim-3 kinase on HSC-T6 cells, si-pim3 (siRNA against pim-3) was transfected into HSC-T6 cells. HSC-T6 cells were subjected to different treatments, including LPS, si-pim3, or si-pim3 plus LPS, and control cells were untreated. Protein expression of pim-3 was detected at 48 h after treatment, and cell proliferation at 24 and 48 h by MTT assay. Apoptosis was detected by flow cytometry, and confirmed with caspase-3 activity assay. RESULTS: LPS promoted HSC-T6 cell proliferation and protected against apoptosis. Significantly delayed upregulation of pim-3 expression induced by LPS occurred at 24 and 48 h for mRNA expression (pim-3/β-actin RNA, 24 or 48 h vs 0 h, 0.81 ± 0.20 or 0.78 ± 0.21 vs 0.42 ± 0.13, P < 0.05), and occurred at 12 h and peaked at 24 and 48 h for protein expression (pim-3/GAPDH protein, 12, or 24 or 48 h vs 0 h, 0.68 ± 0.12, 1.47 ± 0.25 or 1.51 ± 0.23 vs 0.34 ± 0.04, P < 0.01). pim-3 protein was ablated by si-pim3 and upregulated by LPS in HSC-T6 cells at 48 h after treatment (pim-3/GAPDH: si-pim3, si-pim3 plus LPS or LPS vs control, 0.11 ± 0.05, 0.12 ± 0.05 or 1.08 ± 0.02 vs 0.39 ± 0.03, P < 0.01). Ablation of pim-3 by si-pim3 in HSC-T6 cells partly abolished proliferation (OD at 24 h, si-pim3 group or si-pim3 plus LPS vs control, 0.2987 ± 0.050 or 0.4063 ± 0

  10. Estudio del comportamiento tribologico y de las interacciones de superficie de nuevos nanofluidos ionicos

    NASA Astrophysics Data System (ADS)

    Espinosa Rodriguez, Tulia

    tribocorrosion processes. The formation of a coating layer on magnesium alloys from phosphonate imidazolium ionic liquids by immersion and by chronoamperometry has been described. The new coatings reduce the abrasive wear in the magnesium-aluminium alloy but they are not effective in the magnesium-zinc alloy, which prevent the formation of continuous coatings. Los liquidos ionicos son sales liquidas a temperatura ambiente o bajas temperaturas que presentan excelentes propiedades fisico-quimicas. En el presente trabajo se estudian como lubricantes en problemas tribologicos complejos como la lubricacion de metales contra si mismos, el desarrollo de lubricantes base agua y de nuevas superficies autolubricadas. Cuando no es posible reducir la friccion y desgaste mediante lubricacion, como en las aleaciones de magnesio, los liquidos ionicos se han estudiado como precursores de recubrimientos protectores. Se han determinado las interacciones superficiales y los procesos de corrosion sobre cobre y sobre acero con diferentes liquidos ionicos proticos y aproticos para desarrollar nuevos lubricantes y aditivos. En el contacto cobre/cobre, excepto el liquido ionico protico derivado del oleato, todos los liquidos ionicos estudiados presentan mejor comportamiento tribologico que el lubricante comercial Polialfaolefina 6. En el contacto acero/zafiro, los nuevos liquidos ionicos proticos son buenos lubricantes cuando se utilizan en estado puro, y, como aditivos en agua, generan peliculas adsorbidas sobre la superficie del metal reduciendo la friccion y el desgaste tras la evaporacion del agua. Para evitar el periodo de alta friccion inicial en presencia de agua, se han generado peliculas superficiales de liquido ionico sobre el acero en condiciones estaticas. El mejor comportamiento lubricante tanto en el contacto cobre/cobre como en el contacto acero/zafiro se obtiene para el liquido ionico protico derivado del anion adipato, con dos grupos carboxilicos. Las interacciones de los grupos

  11. Anxious or Depressed and Still Happy?

    PubMed Central

    Spinhoven, Philip; Elzinga, Bernet M.; Giltay, Erik; Penninx, Brenda W. J. H.

    2015-01-01

    This study aimed to examine cross-sectionally to what extent persons with higher symptom levels or a current or past emotional disorder report to be less happy than controls and to assess prospectively whether time-lagged measurements of extraversion and neuroticism predict future happiness independent of time-lagged measurements of emotional disorders or symptom severity. A sample of 2142 adults aged 18–65, consisting of healthy controls and persons with current or past emotional disorder according to DSM-IV criteria completed self-ratings for happiness and emotional well-being and symptom severity. Lagged measurements of personality, symptom severity and presence of anxiety and depressive disorder at T0 (year 0), T2 (year 2) and T4 (year 4) were used to predict happiness and emotional well-being at T6 (year 6) controlling for demographics. In particular persons with more depressive symptoms, major depressive disorder, social anxiety disorder and comorbid emotional disorders reported lower levels of happiness and emotional well-being. Depression symptom severity and to a lesser extent depressive disorder predicted future happiness and emotional well-being at T6. Extraversion and to a lesser extent neuroticism also consistently forecasted future happiness and emotional well-being independent of concurrent lagged measurements of emotional disorders and symptoms. A study limitation is that we only measured happiness and emotional well-being at T6 and our measures were confined to hedonistic well-being and did not include psychological and social well-being. In sum, consistent with the two continua model of emotional well-being and mental illness, a ‘happy’ personality characterized by high extraversion and to a lesser extent low neuroticism forecasts future happiness and emotional well-being independent of concurrently measured emotional disorders or symptom severity levels. Boosting positive emotionality may be an important treatment goal for persons

  12. Colistin-resistant, lipopolysaccharide-deficient Acinetobacter baumannii responds to lipopolysaccharide loss through increased expression of genes involved in the synthesis and transport of lipoproteins, phospholipids, and poly-β-1,6-N-acetylglucosamine.

    PubMed

    Henry, Rebekah; Vithanage, Nuwan; Harrison, Paul; Seemann, Torsten; Coutts, Scott; Moffatt, Jennifer H; Nation, Roger L; Li, Jian; Harper, Marina; Adler, Ben; Boyce, John D

    2012-01-01

    We recently demonstrated that colistin resistance in Acinetobacter baumannii can result from mutational inactivation of genes essential for lipid A biosynthesis (Moffatt JH, et al., Antimicrob. Agents Chemother. 54:4971-4977). Consequently, strains harboring these mutations are unable to produce the major Gram-negative bacterial surface component, lipopolysaccharide (LPS). To understand how A. baumannii compensates for the lack of LPS, we compared the transcriptional profile of the A. baumannii type strain ATCC 19606 to that of an isogenic, LPS-deficient, lpxA mutant strain. The analysis of the expression profiles indicated that the LPS-deficient strain showed increased expression of many genes involved in cell envelope and membrane biogenesis. In particular, upregulated genes included those involved in the Lol lipoprotein transport system and the Mla-retrograde phospholipid transport system. In addition, genes involved in the synthesis and transport of poly-β-1,6-N-acetylglucosamine (PNAG) also were upregulated, and a corresponding increase in PNAG production was observed. The LPS-deficient strain also exhibited the reduced expression of genes predicted to encode the fimbrial subunit FimA and a type VI secretion system (T6SS). The reduced expression of genes involved in T6SS correlated with the detection of the T6SS-effector protein AssC in culture supernatants of the A. baumannii wild-type strain but not in the LPS-deficient strain. Taken together, these data show that, in response to total LPS loss, A. baumannii alters the expression of critical transport and biosynthesis systems associated with modulating the composition and structure of the bacterial surface. PMID:22024825

  13. A Novel Matrine Derivative WM130 Inhibits Activation of Hepatic Stellate Cells and Attenuates Dimethylnitrosamine-Induced Liver Fibrosis in Rats

    PubMed Central

    Xu, Yang; Peng, Zhangxiao; Ji, Weidan; Li, Xiang; Lin, Xuejing; Qian, Liqiang; Li, Xiaoya; Chai, Xiaoyun; Wu, Qiuye; Gao, Quangen; Su, Changqing

    2015-01-01

    Activation of hepatic stellate cells (HSCs) is a critical event in process of hepatic fibrogenesis and cirrhosis. Matrine, the active ingredient of Sophora, had been used for clinical treatment of acute/chronic liver disease. However, its potency was low. We prepared a high potency and low toxicity matrine derivate, WM130 (C30N4H40SO5F), which exhibited better pharmacological activities on antihepatic fibrosis. This study demonstrated that WM130 results in a decreased proliferative activity of HSC-T6 cells, with the half inhibitory concentration (IC50) of 68 μM. WM130 can inhibit the migration and induce apoptosis in HSC-T6 cells at both concentrations of 68 μM (IC50) and 34 μM (half IC50). The expression of α-SMA, Collagen I, Collagen III, and TGF-β1 could be downregulated, and the protein phosphorylation levels of EGFR, AKT, ERK, Smad, and Raf (p-EGFR, p-AKT, p-ERK, p-Smad, and p-Raf) were also decreased by WM130. On the DMN-induced rat liver fibrosis model, WM130 can effectively reduce the TGF-β1, AKT, α-SMA, and p-ERK levels, decrease the extracellular matrix (ECM) formation, and inhibit rat liver fibrosis progression. In conclusion, this study demonstrated that WM130 can significantly inhibit the activation of HSC-T6 cells and block the rat liver fibrosis progression by inducing apoptosis, suppressing the deposition of ECM, and inhibiting TGF-β/Smad and Ras/ERK pathways. PMID:26167476

  14. The cluster 1 type VI secretion system is a major virulence determinant in Burkholderia pseudomallei.

    PubMed

    Burtnick, Mary N; Brett, Paul J; Harding, Sarah V; Ngugi, Sarah A; Ribot, Wilson J; Chantratita, Narisara; Scorpio, Angelo; Milne, Timothy S; Dean, Rachel E; Fritz, David L; Peacock, Sharon J; Prior, Joanne L; Atkins, Timothy P; Deshazer, David

    2011-04-01

    The Burkholderia pseudomallei K96243 genome encodes six type VI secretion systems (T6SSs), but little is known about the role of these systems in the biology of B. pseudomallei. In this study, we purified recombinant Hcp proteins from each T6SS and tested them as vaccine candidates in the BALB/c mouse model of melioidosis. Recombinant Hcp2 protected 80% of mice against a lethal challenge with K96243, while recombinant Hcp1, Hcp3, and Hcp6 protected 50% of mice against challenge. Hcp6 was the only Hcp constitutively produced by B. pseudomallei in vitro; however, it was not exported to the extracellular milieu. Hcp1, on the other hand, was produced and exported in vitro when the VirAG two-component regulatory system was overexpressed in trans. We also constructed six hcp deletion mutants (Δhcp1 through Δhcp6) and tested them for virulence in the Syrian hamster model of infection. The 50% lethal doses (LD(50)s) for the Δhcp2 through Δhcp6 mutants were indistinguishable from K96243 (<10 bacteria), but the LD(50) for the Δhcp1 mutant was >10(3) bacteria. The hcp1 deletion mutant also exhibited a growth defect in RAW 264.7 macrophages and was unable to form multinucleated giant cells in this cell line. Unlike K96243, the Δhcp1 mutant was only weakly cytotoxic to RAW 264.7 macrophages 18 h after infection. The results suggest that the cluster 1 T6SS is essential for virulence and plays an important role in the intracellular lifestyle of B. pseudomallei. PMID:21300775

  15. Zinc transporter gene expression and glycemic control in post-menopausal women with Type 2 diabetes mellitus.

    PubMed

    Foster, Meika; Chu, Anna; Petocz, Peter; Samman, Samir

    2014-10-01

    Type 2 diabetes mellitus (DM) is associated often with underlying zinc deficiency and nutritional supplements such as zinc may be of therapeutic benefit in the disease. In a randomized, double-blind, placebo-controlled, 12-week trial in postmenopausal women (n=48) with Type 2 DM we investigated the effects of supplementation with zinc (40mg/d) and flaxseed oil (FSO; 2g/d) on the gene expression of zinc transporters (ZnT1, ZnT5, ZnT6, ZnT7, ZnT8, Zip1, Zip3, Zip7, and Zip10) and metallothionein (MT-1A, and MT-2A), and markers of glycemic control (glucose, insulin, glycosylated hemoglobin [HbA1c]). The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. No significant effects of zinc or FSO supplementation were observed on glycemic marker concentrations, HOMA-IR or fold change over 12 weeks in zinc transporter and metallothionein gene expression. In multivariate analysis, the change over 12 weeks in serum glucose concentrations (P=0.001) and HOMA-IR (P=0.001) predicted the fold change in Zip10. In secondary analysis, marginal statistical significance was observed with the change in both serum glucose concentrations (P=0.003) and HOMA-IR (P=0.007) being predictive of the fold change in ZnT6. ZnT8 mRNA expression was variable; HbA1c levels were higher (P=0.006) in participants who exhibited ZnT8 expression compared to those who did not. The significant predictive relationships between Zip10, ZnT6, serum glucose and HOMA-IR are preliminary, as is the relationship between HbA1c and ZnT8; nevertheless the observations support an association between Type 2 DM and zinc homeostasis that requires further exploration. PMID:25156968

  16. Inhibition of cell growth by a hypothalamic peptide.

    PubMed Central

    Redding, T W; Schally, A V

    1982-01-01

    A fraction purified from acetic acid extracts of porcine hypothalami was found to contain significant antimitogenic activity when tested in normal and neoplastic cell lines. Addition of this hypothalamic material (1-100 micrograms/ml) to culture media significantly inhibited [3H]thymidine incorporation into cellular DNA in several cell lines. Amino acid incorporation into pituitary proteins and uridine incorporation into RNA were also significantly reduced by this factor(s). Addition to the culture media of this hypothalamic material at 5 micrograms/ml and 50 micrograms/ml per day decreased by 17% and 36%, respectively, cell numbers of 3T6 fibroblast cell cultures. Time-response curves showed that the inhibition of [3H]thymidine incorporation into DNA in 3T6 fibroblast cells begins within 2 hr after adding this fraction to the culture medium. The inhibitory action cannot be explained by a direct cytotoxic effect since 3T6 cells labeled with 51Cr and incubated for 6 hr in the presence of this hypothalamic fraction fail to show an increase in the release of 51Cr into the medium as compared with controls. Incubation with trypsin and chymotrypsin completely abolished the antimitogenic activity of this material and pepsin decreased it. This strongly suggests that the antimitogenic activity exhibited by this fraction is due to a polypeptide(s). These observations provide evidence for the presence in the mammalian hypothalamus of an antimitogenic peptide(s) that may be involved in the regulation of cell proliferation. PMID:6757925

  17. The Crystal Structure and Small-Angle X-Ray Analysis of CsdL/TcdA Reveal a New tRNA Binding Motif in the MoeB/E1 Superfamily

    PubMed Central

    López-Estepa, Miguel; Ardá, Ana; Savko, Martin; Round, Adam; Shepard, William E.; Bruix, Marta; Coll, Miquel; Fernández, Francisco J.; Jiménez-Barbero, Jesús; Vega, M. Cristina

    2015-01-01

    Cyclic N6-threonylcarbamoyladenosine (‘cyclic t6A’, ct6A) is a non-thiolated hypermodification found in transfer RNAs (tRNAs) in bacteria, protists, fungi and plants. In bacteria and yeast cells ct6A has been shown to enhance translation fidelity and efficiency of ANN codons by improving the faithful discrimination of aminoacylated tRNAs by the ribosome. To further the understanding of ct6A biology we have determined the high-resolution crystal structures of CsdL/TcdA in complex with AMP and ATP, an E1-like activating enzyme from Escherichia coli, which catalyzes the ATP-dependent dehydration of t6A to form ct6A. CsdL/TcdA is a dimer whose structural integrity and dimer interface depend critically on strongly bound K+ and Na+ cations. By using biochemical assays and small-angle X-ray scattering we show that CsdL/TcdA can associate with tRNA with a 1:1 stoichiometry and with the proper position and orientation for the cyclization of t6A. Furthermore, we show by nuclear magnetic resonance that CsdL/TcdA engages in transient interactions with CsdA and CsdE, which, in the latter case, involve catalytically important residues. These short-lived interactions may underpin the precise channeling of sulfur atoms from cysteine to CsdL/TcdA as previously characterized. In summary, the combination of structural, biophysical and biochemical methods applied to CsdL/TcdA has afforded a more thorough understanding of how the structure of this E1-like enzyme has been fine tuned to accomplish ct6A synthesis on tRNAs while providing support for the notion that CsdA and CsdE are able to functionally interact with CsdL/TcdA. PMID:25897750

  18. Self-Assembly, Molecular Ordering, and Charge Mobility in Solution-Processed Ultrathin Oligothiophene Films

    SciTech Connect

    Murphy,A.; Chang, P.; VanDyke, P.; Liu, J.; Frechet, J.; Subramanian, V.; Delongchamp, D.; Sambasivan, S.; Fischer, D.; Lin, E.

    2005-01-01

    Symmetrical {alpha}, {omega}-substituted quarter-(T4), penta-(T5), sexi-(T6), and heptathiophene (T7) oligomers containing thermally removable aliphatic ester solubilizing groups were synthesized, and their UV-vis and thermal characteristics were compared. Spun-cast thin films of each oligomer were examined with atomic force microscopy and near-edge X-ray absorption fine structure spectroscopy to evaluate the ability of the material to self-assemble from a solution-based process while maintaining complete surface coverage. Films of the T5-T7 oligomers self-assemble into crystalline terraces after thermal annealing with higher temperatures required to affect this transformation as the size of the oligomers increases. A symmetrical {alpha}, {omega}-substituted sexithiophene (T6-acid) that reveals carboxylic acids after thermolysis was also prepared to evaluate the effect of the presence of hydrogen-bonding moieties. The charge transport properties for these materials evaluated in top-contact thin film transistor devices were found to correlate with the observed morphology of the films. Therefore, the T4 and the T6-acid performed poorly because of incomplete surface coverage after thermolysis, while T5-T7 exhibited much higher performance as a result of molecular ordering. Increases in charge mobility correlated to increasing conjugation length with measured mobilities ranging from 0.02 to 0.06 cm2/(V{center_dot}s). The highest mobilities were measured when films of each oligomer had an average thickness between one and two monolayers, indicating that the molecules become exceptionally well-ordered during the thermolysis process. This unprecedented ordering of the solution-cast molecules results in efficient charge mobility rarely seen in such ultrathin films.

  19. 125I brachytherapy in the palliation of painful bone metastases from lung cancer after failure or rejection of conventional treatments

    PubMed Central

    Gilani, Saba; Zhong, Zhihui; Zhang, Tao; Zhang, Fujun; Gao, Fei

    2016-01-01

    Purpose This study sought to assess the safety and effect of 125I seed implantation for palliation of painful bone metastases from lung cancer after failure or rejection of conventional treatments. Materials and Methods 89 patients with painful bone metastases secondary to lung cancer were consented and enrolled in this study from June 2013 to May 2015. All patients had failed or refused conventional treatments underwent percutaneous CT-guided 125I seed implantation. The Brief Pain Inventory (BPI) was used to measure pain intensity prior to treatment (T0), 2, 4, 6, 8 and 12 weeks (T2, T4, T6, T8 and T12) after treatment in a 24-hour period. Analgesic, quality of life (QOL) scores and complications were also recorded. Four patients were excluded as they were lost to follow-up or had incomplete data. Results 85 patients with 126 bone metastases from lung cancer were treated. There were significantly lower scores after treatment in the visual analog scale (VAS) and analgesic. The VAS scores for worst pain was 6.3±1.8 at T0. At T2, T4, T6, T8 and T12, the score in a 24-hour period decreased to 4.9±1.2 (P<0.01), 3.7±1.3 (P<0.01), 3.4±1.2 (P<0.01), 2.6±0.9 (P<0.01), and 1.4±0.8 (P<0.01) respectively. Comparison of QOL scores showed improvements including sleep, appetite, spiritual state, and fatigue at T2, T4, T6, T8 and T12 when compared to T0. No serious complications or massive bleeding were observed. Conclusions 125I brachytherapy is a safe and effective method for palliation of painful bone metastases from lung cancer after failure or rejection of conventional treatments. PMID:26919235

  20. Influence of Aging Treatments on Alterations of Microstructural Features and Stress Corrosion Cracking Behavior of an Al-Zn-Mg Alloy

    NASA Astrophysics Data System (ADS)

    Rout, Prasanta Kumar; Ghosh, M. M.; Ghosh, K. S.

    2015-07-01

    7xxx series Al-Zn-Mg-(Cu) alloys have higher strength in their peak-aged (T6) states compared with other age-hardenable aluminum alloys; however, the maximum strength peak-aged state is more susceptible to stress corrosion cracking (SCC) which leads to catastrophic failure. The over-aged (T7) temper with 10-15% lower strength has higher resistance to SCC requiring oversized structural aerospace component applications. The medium-strength AA7017 Al-Zn-Mg weldable alloy without Cu is also prone to SCC under certain environmental conditions. In the present investigation, the SCC behaviors of an AA7017 Al-Zn-Mg alloys of different tempers have been assessed. Specific aging schedules have been adapted to an AA7017 alloy to produce various tempers, e.g., under-, peak-(T6), over-(T7), and highly over-aged tempers. Artificial aging behavior of the AA7017 alloy has been characterized by hardness, electrical conductivity measurements, x-ray diffraction, differential scanning calorimetry, and electrochemical studies. Slow strain rate test technique was used to assess the SCC behaviors of the AA7017 alloys of under-, T6, T7, and highly over-aged tempers in 3.5 wt.% NaCl solution at free corrosion potential (FCP) and at applied anodic potential, as well. Results revealed that the AA7017 alloy tempers are not susceptible to SCC in 3.5 wt.% NaCl solution at FCP, but severely damaging to SCC at applied anodic potentials. Microstructural features, showing a non-recrystallized grain structure and the presence of discrete, widely spaced, not-interconnected η precipitates at the grain boundaries, are the contributive factors by virtue of which the alloy tempers at FCP did not exhibit SCC. However, the applied anodic potential resulted in rapid metal dissolution from the grain boundary region and led to SCC. The local anodic dissolution (LAD) is believed to be the associated SCC mechanism.

  1. Effects of resistance training on classic and specific bioelectrical impedance vector analysis in elderly women.

    PubMed

    Fukuda, David H; Stout, Jeffrey R; Moon, Jordan R; Smith-Ryan, Abbie E; Kendall, Kristina L; Hoffman, Jay R

    2016-02-01

    Raw bioelectrical impedance analysis (BIA) data [resistance (R); reactance (Xc)] through bioelectrical impedance vector analysis (BIVA) and phase angle (PhA) have been used to evaluate cellular function and hydration status. The purpose of this investigation was to examine the effects of resistance training (RT) on classic and specific BIVA in elderly women. Twenty women (mean ± SD; age: 71.9 ± 6.9 years; BMI: 24.5 ± 3.0 kg m(-2)) completed a 6-month RT program. Whole-body, single-frequency BIA, body geometry, and leg strength (5RM) measures were completed at baseline (t0), 3 months (t3), and 6 months (t6). The mean impedance vector displacements were compared using Hotelling's T(2) test to evaluate changes in R and Xc relative to height (R/ht; Xc/ht) or body volume (Rsp; Xcsp) estimated from the arms, legs, and trunk. 5RM, PhA, and BIVA variables were compared using ANOVA. PhA improved at t6 (p < 0.01), while 5RM improved at t3 and t6 (p < 0.01). Using classic BIVA, 6 months (T(2) = 31.6; p < 0.01), but not 3 months of RT (T(2) = 4.5; p = 0.20), resulted in significant vector migration. Using specific BIVA, 6 months (T(2) = 24.4; p < 0.01), but not 3 months of RT (T(2) = 5.5; p = 0.10), also resulted in significant vector migration. 5RM was correlated to both PhA (r = 0.48-56) and Xcsp (r = 0.45-53) at all time points. Vector displacements were likely the result of improved cellular integrity (Xcsp) and cellular health (PhA). PMID:26657810

  2. A Novel Matrine Derivative WM130 Inhibits Activation of Hepatic Stellate Cells and Attenuates Dimethylnitrosamine-Induced Liver Fibrosis in Rats.

    PubMed

    Xu, Yang; Peng, Zhangxiao; Ji, Weidan; Li, Xiang; Lin, Xuejing; Qian, Liqiang; Li, Xiaoya; Chai, Xiaoyun; Wu, Qiuye; Gao, Quangen; Su, Changqing

    2015-01-01

    Activation of hepatic stellate cells (HSCs) is a critical event in process of hepatic fibrogenesis and cirrhosis. Matrine, the active ingredient of Sophora, had been used for clinical treatment of acute/chronic liver disease. However, its potency was low. We prepared a high potency and low toxicity matrine derivate, WM130 (C30N4H40SO5F), which exhibited better pharmacological activities on antihepatic fibrosis. This study demonstrated that WM130 results in a decreased proliferative activity of HSC-T6 cells, with the half inhibitory concentration (IC50) of 68 μM. WM130 can inhibit the migration and induce apoptosis in HSC-T6 cells at both concentrations of 68 μM (IC50) and 34 μM (half IC50). The expression of α-SMA, Collagen I, Collagen III, and TGF-β1 could be downregulated, and the protein phosphorylation levels of EGFR, AKT, ERK, Smad, and Raf (p-EGFR, p-AKT, p-ERK, p-Smad, and p-Raf) were also decreased by WM130. On the DMN-induced rat liver fibrosis model, WM130 can effectively reduce the TGF-β1, AKT, α-SMA, and p-ERK levels, decrease the extracellular matrix (ECM) formation, and inhibit rat liver fibrosis progression. In conclusion, this study demonstrated that WM130 can significantly inhibit the activation of HSC-T6 cells and block the rat liver fibrosis progression by inducing apoptosis, suppressing the deposition of ECM, and inhibiting TGF-β/Smad and Ras/ERK pathways. PMID:26167476

  3. Survival of North American genotypes of Trichinella in frozen pork.

    PubMed

    Hill, D E; Forbes, L; Zarlenga, D S; Urban, J F; Gajadhar, A A; Gamble, H R

    2009-12-01

    North American genotypes of Trichinella spiralis (T-1), Trichinella nativa (T-2), Trichinella pseudospiralis (T-4), Trichinella murrelli (T-5), and Trichinella T-6 were examined for susceptibility to freezing in pork using time-temperature combinations that have been proven to inactivate T. spiralis. Infections were established in 3-month-old pigs of mixed sex and breed by oral inoculation of 10,000 muscle larvae (ML) (all genotypes, rodent-derived ML), 20,000 ML (T-1, T-4, and T-5; cat-derived ML), or 30,000 ML (T-2 and T-6; cat-derived ML). Pigs were euthanized 60 days postinoculation. Muscles from the tongue, masseter muscles, diaphragm, triceps, hams, neck, rump, and loins were ground, pooled, and mixed to ensure even distribution of larvae. Samples (20 g) containing each Trichinella species, genotype, and source combination were placed in heat-sealable pouches, transferred to a constant temperature refrigerant bath, and maintained according to defined time and temperature combinations. Larvae recovered from cold-treated pork samples were inoculated into mice to determine infectivity. Results indicated that the time-temperature combinations known to render pork safe for T. spiralis are sufficient to inactivate T. nativa and T-6 (the freeze-resistant isolates), T. murrelli (the most common sylvatic species in the United States excluding Alaska), and T. pseudospiralis (a species that lacks a muscle nurse cell). These data close a gap in knowledge about the effectiveness of freezing for inactivating these parasites in pork and should alleviate concern about the safety of frozen pork products from the United States. PMID:20003740

  4. Targeted CT-Guided Epidural Blood Patch for Treatment of Spontaneous Intracranial Hypotension Due to Calcified Intradural Thoracic Disc Herniation

    PubMed Central

    Agarwal, V.; Sreedher, G.; Rothfus, W.E.

    2013-01-01

    Summary Calcified thoracic intradural disc herniations have recently been reported as a cause of spontaneous intracranial hypotension (SIH). We report successful treatment of SIH with a targeted CT-guided epidural blood patch. A 57-year-old man presented to the emergency department with a two-week history of progressively debilitating headache. CT and MRI of the brain showed findings consistent with intracranial hypotension and MRI of the spine showed findings consistent with CSF leak. Subsequent CT myelogram of the thoracic spine confirmed the presence of CSF leak and calcified disc herniations at the T6-7, T7-8 and T8-9 levels indenting the ventral dura and spinal cord. The calcified disc herniation at T6-7 had an intradural component and was therefore the most likely site of the CSF leak. Under CT fluoroscopic guidance, a 20-gauge Tuohy needle was progressively advanced into the dorsal epidural space at T6-7. After confirmation of needle tip position, approximately 18cc of the patient's own blood was sterilely removed from an arm vein and slowly re-injected into the dorsal epidural space. With satisfactory achievement of clot formation, the procedure was terminated. The patient tolerated the procedure well. The next morning, his symptoms had completely resolved and he was neurologically intact. At five-week follow up, he was symptom-free. Targeted epidural blood patch at the site of presumed CSF leak can be carried out in a safe and effective manner using CT fluoroscopic guidance and can be an effective alternative to open surgical management in selected patients. PMID:23472734

  5. Variation of vlhA gene in Mycoplasma synoviae clones isolated from chickens.

    PubMed

    Slavec, Brigita; Berčič, Rebeka Lucijana; Cizelj, Ivanka; Narat, Mojca; Zorman-Rojs, Olga; Dovč, Peter; Benčina, Dušan

    2011-10-01

    Mycoplasma synoviae synthesizes haemagglutinin VlhA, which cleaves into the N-terminal part, a lipoprotein MSPB, and a C-terminal part MSPA. Previous studies have shown that the 3'-end of the expressed vlhA gene can recombine with vlhA pseudogenes in a process called gene conversion, but there have been no data about diversification of the expressed vlhA gene in M. synoviae populations replicating in chickens. Following intratracheal inoculation with the M. synoviae strain ULB 02/T6, which showed only minor vlhA gene variation prior to inoculation, we investigated temporal changes in MSPB epitopes defined by monoclonal antibodies (mAbs) 3B4 and 50, as well as diversification of the vlhA gene sequence in M. synoviae populations recovered from chicken tracheas. In cultures isolated 8 and 18 days post inoculation (p.i.), most colonies showed variation of MSPB epitopes for mAbs 3B4 and 50. They also changed 3'-end vlhA gene sequences. Further diversity of the vlhA gene occurred in cultures isolated 8 weeks and 5 months p.i. The vlhA gene sequences from isolated cultures shared only 65 to 80% sequence identity with vlhA gene of the inoculated ULB 02/T6 culture. Notably, in most of those cultures their vlhA gene sequences contained stop codons potentially causing premature terminations of translation. Interestingly, in one culture isolated 8 weeks p.i. (clone T6-8W/IT2A) the 3'-vlhA gene sequence was identical in the last 1140 bases to that of the first vlhA pseudogene positioned the most far (upstream) of the expressed vlhA gene. This is the first demonstration of temporal diversity of the vlhA gene in M. synoviae populations isolated from chicken tracheas. PMID:21830862

  6. Paenibacillus zeae sp. nov., isolated from maize (Zea mays L.) seeds.

    PubMed

    Liu, Yang; Zhai, Lei; Wang, Ronghuan; Zhao, Ran; Zhang, Xin; Chen, Chuanyong; Cao, Yu; Cao, Yanhua; Xu, Tianjun; Ge, Yuanyuan; Zhao, Jiuran; Cheng, Chi

    2015-12-01

    Four Gram-stain-positive bacterial strains, designated 6R2T, 6R18, 3T2 and 3T10, isolated from seeds of hybrid maize (Zea mays L., Jingke 968) were investigated using a polyphasic taxonomic approach. Cells were aerobic, motile, spore-forming and rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolates may represent a novel species of the genus Paenibacillus, the four closest neighbours being Paenibacillus lautus NRRL NRS-666T (97.1 % similarity), Paenibacillus glucanolyticus DSM 5162T (97.0 %), Paenibacillus lactis MB 1871T (97.0 %) and Paenibacillus chibensis JCM 9905T (96.8 %). The DNA G+C content of strain 6R2T was 51.8 mol%. Its polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The predominant respiratory quinone was menaquinone 7 (MK-7) and the major fatty acids were anteiso-C15 : 0 and iso-C14 : 0. Strains 6R2T, 6R18, 3T2 and 3T10 were clearly distinguished from the above type strains using phylogenetic analysis, DNA-DNA hybridization, and a range of physiological and biochemical characteristics. It is evident from the genotypic and phenotypic data that strains 6R2T, 6R18, 3T2 and 3T10 represent a novel species of the genus Paenibacillus, for which the name Paenibacillus zeae sp. nov. is proposed. The type strain is 6R2T ( = KCTC 33674T = CICC 23860T). PMID:26373452

  7. Small and middle T antigens contribute to lytic and abortive polyomavirus infection

    SciTech Connect

    Tuerler, H.; Salomon, C.

    1985-02-01

    Using three different polyomavirus hr-t mutants and two polyomavirus mlT mutants, the authors studied induction of S-phase by mutants and wild-type virus in quiescent mouse kidney cells, mouse 3T6 cells, and FR 3T3 cells. At different times after infection, they measured the proportion of T-antigen-positive cells, the incorporation of (/sup 3/H)thymidine, the proportion of DNA-synthesizing cells, and the increase in total DNA, RNA, and protein content of the cultures. In permissive mouse cells, they also determined the amount of viral DNA and the proportion of viral capsid-producing cells. In polyomavirus hr-t mutant-infected cultures, the onset of host DNA replication was delayed by several hours, and a smaller proportion of T-antigen-positive cells entered S-phase than in wild-type-infected cultures. Of the two polyomavirus mlT mutants studied, dl-23 behaved similarly to wild-type virus in many, but not all, parameters tested. The poorly replicating but well-transforming mutant dl-8 was able to induce S-phase, and (in permissive cells) progeny virus production, in only about one-third of the T-antigen-positive cells. From the experiments, the authors concluded that mutations affecting small and middle T-antigen cause a reduction in the proportion of cells responding to virus infection and a prolongation of the early phase, i.e., the period before cells center S-phase. In hr-t mutant-infected mouse 3T6 cells, production of viral DNA was <10% of that in wild-type-infected cultures; low hr-t progeny production in 3T6 cells was therefore largely due to poor viral DNA replication.

  8. A numerical analysis of empty and foam-filled aluminium conical tubes under oblique impact loading

    NASA Astrophysics Data System (ADS)

    Mat, Fauziah; Ismail, Khairul Azwan; Yaacob, Sazali

    2015-05-01

    In real impact applications, an energy absorber rarely sustains dynamic loading either axial or oblique but a combination of both. Established studies have proved that thin-walled tube is an excellent energy absorber under dynamic loading. Furthermore, the introduction of foam filling successfully enhanced the energy absorption capacity of thin-walled tube. However, the understanding of its response under oblique loading has yet been fully explored. Moreover, emerging in automotive industry has lead to increase interests on lightweight materials such as aluminium alloy. As such, this paper presents the crushing behaviour of empty and foam-filled aluminium alloy (AA6061-T6) conical tubes under oblique impact loading using a validated nonlinear finite element (FE) code, LS-DYNA. The study aims to assess the effect of foam filling on the energy absorption of AA6061-T6 tubes for variations in filler density. In fact, to the best of our knowledge, this study is the first attempt to evaluate a response of empty and foam-filled aluminum conical tube by using an experimentally validated model under oblique dynamic loading conditions. Good correlations between the numerical and experimental results were observed. The study show that initial peak force and the energy absorption increase with increasing filler density under axial and oblique loading. On the other hand, the effect of foam filling (0.534 g/cm3 aluminium foam filler) is less pronounced for the initial peak force under axial impact loading. Furthermore, the initial peak force and dynamic force of empty and foam-filled AA6061-T6 conical tubes decrease as the load angle increases from 0 deg to 20 deg hence reduces the energy absorption capacity.

  9. Evaluation of immune markers in asymptomatic AIDS patients receiving fish oil supplementation.

    PubMed

    Virgili, N; Farriol, M; Castellanos, J M; Giró, M; Podzamczer, D; A M, P

    1997-10-01

    The effects of oral fish oil (FO) supplementation (8 g/day, capsules) on nutritional status and selected immune markers (CD4/CD8 ratio, IL-1beta, erythrocyte MDA release, dehydroepiandrosterone sulfate [DHEA-S]) were studied in a homogeneous group of asymptomatic HIV-infected patients during 6 weeks. All subjects were classified clinically as A2 according to the CDC revised criteria (mean CD4 count 290 +/-123 cells/mm(3)) and were receiving zidovudine retroviral treatment. The calculated mean energy intake was 3437 +/- 372 Kcal/d, composed of 14% protein, 38% lipids and 48% carbohydrates, and was not modified during the study. The anthropometric parameters, and hematological and plasma biochemistry data showed non-significant changes after FO supplementation. Mean malonyldialdehyde (MDA) release before treatment was: unstimulated 71.5 +/- 37 and stimulated 350.9 +/- 79.8 nmol/g Hb. After FO supplementation (T(6)) MDA release showed unstimulated values of 96.1 +/- 62, and a significant increase after stimulation of 614.1 106.4 nmol/g Hb, which was, however, within the normal range. In the patient's samples, IL-1beta levels in the unstimulated blood culture showed a statistical increase with respect to the normal range before (T(0)) and after (T(6)) FO supplementation with a slight decrease after (mean 49.8 vs 40.9 pg/ml). The stimulated IL-1beta levels after treatment showed a statistically significant decrease that was maintained within the normal range (T(0): 797.7 vs T(6): 535.6 pg/ml). Taken collectively, these results suggest a tendency toward improvement in immune function. PMID:16844605

  10. Temperature effects on the deformation and fracture of Al-Li-Cu-In alloys

    NASA Technical Reports Server (NTRS)

    Wagner, John A.; Gangloff, Richard P.

    1991-01-01

    The crack initiation and growth fracture resistance of Al-Cu-Li and Al-Cu-Li-In alloys were characterized and optimized for cryogenic tank applications. Presently, the effects of stress state and temperature is being determined on the fracture toughness and fracture mechanisms of commercially available Vintage 3 2090-T81 and experimental 2090+In-T6. Precracked J-integral specimens of both alloys were tested at ambient and cryogenic temperatures in the plane stress and plane strain conditions. Considering ambient temperature, results showed that 2090-T81 exhibited the highest toughness in both plane strain and plane stress conditions. For the plane strain condition, reasonable crack initiation and growth toughness of 1090-T81 are associated with a significant amount of delamination and transgranular fracture. Plane stress toughnesses were higher and fracture was characterized by shear cracking with minimal delaminations. In comparisons, the fracture behavior of 2090+In-T6 is significantly degraded by subgrain boundary precipitation. Toughness is low and characterized by intersubgranular fracture with no delamination in the plane stress or plane strain conditions. Intersubgranular cracking is a low energy event which presumably occurs prior to the onset of slip band cracking. Copious grain boundary precipitation is atypical of commercially available 2090. At cryogenic temperatures, both alloys exhibit increased yield strength, toughness, and amount of delamination and shear cracking. The change in fracture mode of 2090+In-T6 from intersubgranular cracking at ambient temperature to a combination of intersubgranular cracking, shear cracking, and delamination at cryogenic temperature is the subject of further investigation.

  11. Reconstitution and characterization of eukaryotic N6-threonylcarbamoylation of tRNA using a minimal enzyme system

    PubMed Central

    Wan, Leo C. K.; Mao, Daniel Y. L.; Neculai, Dante; Strecker, Jonathan; Chiovitti, David; Kurinov, Igor; Poda, Gennadiy; Thevakumaran, Neroshan; Yuan, Fang; Szilard, Rachel K.; Lissina, Elena; Nislow, Corey; Caudy, Amy A.; Durocher, Daniel; Sicheri, Frank

    2013-01-01

    The universally conserved Kae1/Qri7/YgjD and Sua5/YrdC protein families have been implicated in growth, telomere homeostasis, transcription and the N6-threonylcarbamoylation (t6A) of tRNA, an essential modification required for translational fidelity by the ribosome. In bacteria, YgjD orthologues operate in concert with the bacterial-specific proteins YeaZ and YjeE, whereas in archaeal and eukaryotic systems, Kae1 operates as part of a larger macromolecular assembly called KEOPS with Bud32, Cgi121, Gon7 and Pcc1 subunits. Qri7 orthologues function in the mitochondria and may represent the most primitive member of the Kae1/Qri7/YgjD protein family. In accordance with previous findings, we confirm that Qri7 complements Kae1 function and uncover that Qri7 complements the function of all KEOPS subunits in growth, t6A biosynthesis and, to a partial degree, telomere maintenance. These observations suggest that Kae1 provides a core essential function that other subunits within KEOPS have evolved to support. Consistent with this inference, Qri7 alone is sufficient for t6A biosynthesis with Sua5 in vitro. In addition, the 2.9 Å crystal structure of Qri7 reveals a simple homodimer arrangement that is supplanted by the heterodimerization of YgjD with YeaZ in bacteria and heterodimerization of Kae1 with Pcc1 in KEOPS. The partial complementation of telomere maintenance by Qri7 hints that KEOPS has evolved novel functions in higher organisms. PMID:23620299

  12. Local control of embryonal rhabdomyosarcoma in children by radiation therapy when combined with chemotherapy

    SciTech Connect

    Jereb, B.; Ghavimi, F.; Exelby, P.; Zang, E.

    1980-07-01

    Between August 1970 and March 1978, 58 patients with embryonal rhabdomyosarcoma (ERMS) were treated at the Radiation Therapy and Pediatric Departments of MSKCC. Chemotherapy was given according to T2 protocol (sequential administration of dactinomycin, vincristine, adriamycin and cyclophosphamide) or the T6 protocol (simultaneous administration of the previous drugs plus bleomycin, methotrexate and BCNU), which was introduced in 1975. The primary tumor or regional metastases were completely or partially removed in 43 patients, while biopsy was the only surgical procedure in 15. There were 41 boys and 17 girls, between 4 months and 19 years old. Eight had stage I-B disease (microscopic residual), 16 stage II (gross residual), 24 stage III (node metastases), and 10 patients stage IV (disseminated tumors). Thirty-five patients were treated with T2 protocol, twenty-three with T6 protocol. Sixteen patients received more than 5000 rad, 21 had between 4000 and 5000 rad and 21 had less than 4000 rad. Forty-four patients are alive, 38 of them disease free. Local tumor control was not achieved in 14 patients, 10 of them were treated with T2 and 4 with T6. There were no local failures in patients treated for microscopic disease with doses between 3000 and 4000 rad. In patients treated for bulky tumors with 4000 to 5000 rad there were 3 failures out of 11 tumors and 3 out of 17 in those treated with higher doses. Radiation doses 3000 to 4000 rad were sufficient for local control of microscopic disease and 4000 to 5000 rad were as effective for control of bulky tumors as higher doses.

  13. Thermal conductance of gold plated metallic contacts at liquid helium temperatures

    NASA Technical Reports Server (NTRS)

    Kittel, Peter; Spivak, Alan L.; Salerno, Louis J.

    1992-01-01

    The thermal conductance of gold plated OFHC copper, 6061-T6 aluminum, free-machining brass, and 304 stainless steel contacts has been measured over the temperature range of 1.6 to 4.2 K, with applied forces from 22 N to 670 N. The contact surfaces were prepared with a 0.8 micron lapped finish prior to gold coating. It was found that for all materials, except stainless steel, the thermal conductance was significantly improved as the result of gold coating the contact surfaces.

  14. Theoretical investigations of EPR g factors for Ce3+ ion at monoclinic Cs site in YAlO3 crystal

    NASA Astrophysics Data System (ADS)

    Liu, Hong-Gang; Zheng, Wen-Chen

    2015-01-01

    Three EPR principal g values (gx, gy and gz) for monoclinic (Cs) Ce3+ center in YAlO3 crystal are calculated by the complete diagonalization (of energy matrix) method (CDM) based on the superposition model (SPM) analysis. The calculated g factors are more reasonably closer to experimental results reported by Asatryan et al. (2002) than their same work in 1997. The reliability of fitted crystal-field parameters of YAP:Ce3+ crystal is also analyzed. In SPM calculations, the seeming abnormal negative power-law exponent t6 is found to be actually reasonable and its underlying cause may be explained by future ab initio studies.

  15. Emission Measure Distribution and Heating of Two Active Region Cores

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2011-01-01

    Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an approximate power-law form EM/T(exp 2.4) from log T = 5.55 up to a peak at log T = 6.57. The observations are explained extremely well by a simple nanoflare model. However, in the absence of additional constraints, the observations could possibly also be explained by steady heating.

  16. Small screw study: Interim report on fastener tensile strength and optimum thread depth

    SciTech Connect

    Diegert, K.V.; Dorrell, L.R.; Reese, R.T.; Lazarus, L.J.; Allied-Signal Aerospace Co., Kansas City, MO . Kansas City Div.)

    1989-10-01

    This report summarizes about 1260 tests performed on small threaded fasteners (equal to or less than 1/4 inch in diameter and designated as 1/4-20 UNC, {number sign}4-40 UNC, {number sign}2-56 UNC, and 1.0 UNM). Tests determined the tensile strengths of the screws, the lengths of engagement needed to develop the full tensile strengths when the screws were engaged in 6061-T6 Aluminum, Hiperco 50, and 303 Stainless Steel, and whether relationships existed between the tensile strengths and Knoop Micro-Hardness measurements taken on the threaded ends of the screws. 17 figs., 13 tabs.

  17. Engineering of the Stellarator of Costa Rica: SCR-1

    NASA Astrophysics Data System (ADS)

    Mora, J.; Vargas, V. I.; Otarola, C.; Piedra, C.; Jimenez, W.; Esquivel, L.; Esquivel, R.; Sanchez, K.; Gonzalez, J.; Asenjo, J.; Fonseca, L.

    2015-03-01

    This Paper aims at briefly describing the challenge of the design and construction of the Stellarator of Costa Rica 1 (SCR-1) [1]. The SCR-1 is a small modular Stellarator for magnetic confinement of plasma (Ro=0.238 m, =0.059 m, Ro/a>4.0, expected plasma volume ≈ 0.016 m3, 10 mm thickness 6061-T6 aluminum vacuum vessel) developed by the Plasma Laboratory for Fusion Energy and Applications of the Instituto Tecnológico de Costa Rica (ITCR).

  18. Electron beam weld development on a Filter Pack Assembly. Final report

    SciTech Connect

    Dereskiewicz, J.P.

    1994-06-01

    A continuous electron beam welding procedure was developed to replace the manual gas tungsten arc welding procedure on the Filter Pack Assembly. A statistical study was used to evaluate the feasibility of electron beam welding 6061-T6 aluminum covers to A356 cast weldments throughout the joint tolerance range specified on product drawings. Peak temperature exposures were not high enough to degrade the heat sensitive electrical components inside the cast weldment. Actual weldments with alodine coating on the weld joint area were successfully cleaned using a nonmetallic fiberglass brush cleaning method.

  19. Detection of Photosynthetic Performance of Stipa bungeana Seedlings under Climatic Change using Chlorophyll Fluorescence Imaging

    PubMed Central

    Song, Xiliang; Zhou, Guangsheng; Xu, Zhenzhu; Lv, Xiaomin; Wang, Yuhui

    2016-01-01

    In this study, the impact of future climate change on photosynthetic efficiency as well as energy partitioning in the Stipa bungeana was investigated by using chlorophyll fluorescence imaging (CFI) technique. Two thermal regimes (room temperature, T0: 23.0/17.0°C; High temperature, T6: 29.0/23.0°C) and three water conditions (Control, W0; Water deficit, W−30; excess precipitation, W+30) were set up in artificial control chambers. The results showed that excess precipitation had no significant effect on chlorophyll fluorescence parameters, while water deficit decreased the maximal quantum yield of photosystem II (PSII) photochemistry for the dark-adapted state (Fv/Fm) by 16.7%, with no large change in maximal quantum yield of PSII photochemistry for the light-adapted state (FV′/FM′) and coefficient of the photochemical quenching (qP) at T0 condition. Under T6 condition, high temperature offset the negative effect of water deficit on Fv/Fm and enhanced the positive effect of excess precipitation on Fv/Fm, Fv′/Fm′, and qP, the values of which all increased. This indicates that the temperature higher by 6°C will be beneficial to the photosynthetic performance of S. bungeana. Spatial changes of photosynthetic performance were monitored in three areas of interest (AOIs) located on the bottom, middle and upper position of leaf. Chlorophyll fluorescence images (Fv/Fm, actual quantum yield of PSII photochemistry for the light-adapted state (ΦPSII), quantum yield of non-regulated energy dissipation for the light-adapted state (ΦNO) at T0 condition, and ΦPSII at T6 condition) showed a large spatial variation, with greater value of ΦNO and lower values of Fv/Fm and ΦPSII in the upper position of leaves. Moreover, there was a closer relationship between ΦPSII and ΦNO, suggesting that the energy dissipation by non-regulated quenching mechanisms played a dominant role in the yield of PSII photochemistry. It was also found that, among all measured fluorescence

  20. 3. Photographic copy of roof truss construction details for Building ...

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

    3. Photographic copy of roof truss construction details for Building 4505, Taylor & Barnes, Architects & Engineers, 803 W. Third Street, Los Angeles California, O.C.E. Office of Civil Engineer Job No. A(9-10), Military Construction: Materiel Command Flight Test Base, Muroc, California, Hangar and Auxiliary Buildings: Hangar Type P-A, Detail of Trusses T-2, T-3, T-4, T-5 & T6, Sheet No. 9, March 1944. A similar drawing for truss T-l is included in project field notes. Reproduced from the holdings of the National Archives, Pacific Southwest Region - Edwards Air Force Base, North Base, Hangar, End of North Base Road, Boron, Kern County, CA

  1. FRICTION STIR MICROSTRUCTURAL MODIFICATION OF INVESTMENT CAST F357

    SciTech Connect

    Jana, s.; Mishra, Rajiv S.; Chou, H. N.; Herling, Darrell R.

    2007-02-09

    A hypoeutectic Al-Si alloy has been friction stir processed in this study using various run parameter combinations. Tensile test results indicate at least three times improvement in ductility value over as-cast T6 condition because of refinement in Si particle size. Si particle size and shape has been quantified and correlated with mechanical properties. Tool rotation rate seems to have the most significant effect on properties. Higher tool rotation rate resulted in more uniform and homogeneous microstructure though some anomaly is observed at very high tool rotation rate.

  2. Space-based visible all-reflective stray light telescope

    NASA Astrophysics Data System (ADS)

    Wang, Dexter; Gardner, Leo R.; Wong, Wallace K.; Hadfield, Peter

    1991-08-01

    A 6-inch diameter aperture space-based visible telescope has been optimized to perform surveillance against the space background with earth albedo as a primary source of straylight. A three mirror off-axis anastigmat has been designed to cover a 1.4 degree(s) by 6.6 degree(s) field- of-view with 60 (mu) radian spatial resolution. The telescope body and optics are constructed of 6061-T6 aluminum to provide a thermally stable optical system. The optical elements are 'superfinished' to minimize scatter. Extensive baffles and stops are utilized to further reduce straylight. The telescope will be used on the Midcourse Space Experiment platform.

  3. Quantitative assessment of autonomic dysreflexia with combined spectroscopic and perfusion probes

    NASA Astrophysics Data System (ADS)

    Ramella-Roman, Jessica C.; Pfefer, Allison; Hidler, Joseph

    2009-02-01

    Autonomic Dysreflexia (AD) is an uncontrolled response of sympathetic output occurring in individuals with an injury at the sixth thoracic (T6) neurologic level. Any noxious stimulus below the injury level can trigger an AD episode. Progression of an AD attack can result in severe vasoconstriction below the injury level. Skin oxygenation can decrease up to 40% during an AD event. We present a quantitative and non-invasive method of assessing the progression of an AD event by measuring patient's skin oxygen levels and blood flow using a fiber optic based system.

  4. Thermal contact conductance between metals in a vacuum environment

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Basic heat transfer data for structural materials used in the Saturn 1B/V 1U component case structural design were obtained. The main emphasis is on thermal contact conductance between dissimilar metallic surfaces, since thermal conductivity values within solids have been sufficiently established previously. The test program outline and test results are described. The following materials were tested: aluminum 6061-T6 (12 samples), aluminum 356 (as cast), almag 35 (as cast), magnesium AZ91C-T4 (4 samples), and mag lithium LA-141 (2 samples).

  5. Photonic heat conduction in Josephson-coupled Bardeen-Cooper-Schrieffer superconductors

    NASA Astrophysics Data System (ADS)

    Bosisio, R.; Solinas, P.; Braggio, A.; Giazotto, F.

    2016-04-01

    We investigate the photon-mediated heat flow between two Josephson-coupled Bardeen-Cooper-Schrieffer (BCS) superconductors. We demonstrate that in standard low temperature experiments involving temperature-biased superconducting quantum interference devices (SQUIDs), this radiative contribution is negligible if compared to the direct galvanic one, but it largely exceeds the heat exchanged between electrons and the lattice phonons. The corresponding thermal conductance is found to be several orders of magnitude smaller, for real experiments setup parameters, than the universal quantum of thermal conductance, κ0(T ) =π kB2T /6 ℏ .

  6. Adherence to Calcium and Vitamin D supplementations: results from the ADVICE Survey

    PubMed Central

    Conti, Francesco; Piscitelli, Prisco; Italiano, Giovanni; Parma, Alessandro; Caffetti, Maria Cristina; Giolli, Lorenzo; Di Tanna, Gian Luca; Guazzini, Andrea; Brandi, Maria Luisa

    2012-01-01

    Summary Objective The ADVICE (ADherence in VItamin-D and Calcium Embedded or not) survey was aimed to evaluate the effect of a patient-focused motivation strategy on the adherence to calcium and vitamin D supplementation. The survey also intended to identify possible factors being able to influence the compliance (i.e. the existence of individual preferences towards different dosages or regimens of supplementation). Methods We planned to involve consecutive patients visited between 2010 and 2011 at 35 centres specialized in diagnosis and treatment of osteoporosis in different Italian regions. Each patient has been requested to declare if he/she was already assuming any supplementation with calcium and vitamin D (naïve or not naïve). All patients underwent a first visit (T0) and two follow up visits at 6 and 12 months (T6 e T12). The assessment of the adherence was measured through the Morinsky Medication Adherence Scale, a score based on 8 different questions, specifically validated to determine therapeutical compliance (0–5: not acceptable; 6–7: acceptable; 8: ideal). Results 732 women (mean age: 66.9; average BMI: 25.3) and 30 men (mean age: 71.9; average BMI: 24.5) were enrolled; 34% of female patients (n=245) and 66% of males (n=20) reported previous fractures. Not naïve patients were 385 (54%). A total of 309 patients (43%) were concurrently assuming an antifracture drug; 229 subjects were osteoporotic (45%), while 224 were osteopenic (44%). The mean Morinsky score in not naïve patients was 5.72, 6.19 and 6.18 at T0, T6, and T12, respectively. Thus, no differences in the Morinsky score were observed between T6 and T12. Naïve patients showed an average Morinsky score of 5.78 at T6 and 6.39 at T12. Older age was not significantly associated with the observed changes in the scores. The onset of AEs related to the supplementation with calcium and vitamin D was able to negatively influence the adherence at the subsequent control point. Bone mineral density

  7. High-speed tapping for N/C machining centers

    SciTech Connect

    Friend, J.P.

    1991-11-01

    Through a series of experiments, a new high-speed tapping technique was developed for N/C machining centers. The new technique produces high quality threads in a fraction of the time previously required, using the same equipment. Threads are produced to precise size and depth in a single pass at speeds up to 5000 rpm. Thread sizes ranged from 0.80 UNM (Unified Miniature Thread Series) (0.0315 in. major diameter) to 0.250-20 UN (Unified Screw Threads) in both blind and through-hole applications. The materials tapped included 17-4 PH stainless steel, 300 series stainless steel, and 6061-T6 aluminum. 10 figs.

  8. The effects of out-of-phase biaxial-strain cycling on low-cycle fatigue.

    NASA Technical Reports Server (NTRS)

    Zamrik, S. Y.; Frishmuth, R. E.

    1973-01-01

    The effects of out-of-phase or nonsychronous straining on low-cycle fatigue was investigated. Biaxial strains were imposed on thin-walled tubular 7075-T6 aluminum specimens by tension-compression and torsion. Phase angles of 0, 30, 45, 60, and 90 deg were applied between two strains. It was found that out-of-phase cycling has an effect on the failure mode in the low-cycle-fatigue range. An analysis based on the maximum total strain in three-dimensional strain is proposed for treating 'out-of-phase' straining conditions in low-cycle fatigue.

  9. [Ultrasound-guided cutaneous intercostal branches nerves block: A good analgesic alternative for gallbladder open surgery].

    PubMed

    Fernández Martín, M T; López Álvarez, S; Mozo Herrera, G; Platero Burgos, J J

    2015-12-01

    Laparoscopic cholecystectomy has become the standard treatment for gallbladder diseases. However, there are still some patients for whom conversion to open surgery is required. This surgery can produce significant post-operative pain. Opioids drugs have traditionally been used to treat this pain, but side effects have led to seeking alternatives (plexus, nerve or fascia blocks or wound). The cases are presented of 4 patients subjected to ultrasound-guided intercostal branches blocks in the mid-axillary line from T6 to T12 with levobupivacaine as an analgesic alternative in open surgery of gallbladder, with satisfactory results. PMID:25896736

  10. Diamidines versus Monoamidines as Anti-Pneumocystis Agents: An in vivo Study

    PubMed Central

    Stanicki, Dimitri; Pottier, Muriel; Gantois, Nausicaa; Pinçon, Claire; Forge, Delphine; Mahieu, Isabelle; Boutry, Sébastien; Vanden Eynde, Jean Jacques; Martinez, Anna; Dei-Cas, Eduardo; Aliouat, El-Moukhtar

    2013-01-01

    Some compounds articulated around a piperazine or an ethylenediamine linker have been evaluated in vitro to determine their activity in the presence of a 3T6 fibroblast cell line and an axenic culture of Pneumocystis carinii, respectively. The most efficient antifungal derivatives, namely N,N′-bis(benzamidine-4-yl)ethane-1,2-diamine (compound 6, a diamidine) and N-(benzamidine-4-yl)-N′-phenylethane-1,2-diamine (compound 7, a monoamidine), exhibited no cytotoxicity and were evaluated in vivo in a rat model. Only the diamidine 6 emerged as a promising hit for further studies. PMID:24276317

  11. Theoretical study of the OH addition to the endocyclic and exocyclic double bonds of the d-limonene

    NASA Astrophysics Data System (ADS)

    Ramírez-Ramírez, Víctor M.; Nebot-Gil, Ignacio

    2005-06-01

    The initial step of the d-limonene + OH gas-phase reaction mechanism was investigated by means of ab initio calculations. We have considered eight different possibilities for the OH addition, corresponding to the two C-C double bonds, the two C atoms of each double bond, and the syn or anti orientation, with respect to the isopropenyl group (endocyclic attack) or the ring cycle (exocyclic attack). Activation energies calculated at the QCISD(T)/6-31G(d)//UMP2/6-31G(d) level, show that there are preferred orientations for the OH addition under atmospheric conditions of temperature and pressure.

  12. Determination of Plate Compressive Strengths at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Heimerl, George J; Roberts, William M

    1950-01-01

    The results of local-instability tests of h-section plate assemblies and compressive stress-strain tests of extruded 75s-t6 aluminum alloy, obtained to determine flat-plate compressive strength under stabilized elevated temperature conditions, are given for temperatures up to 600 degrees F. The results show that methods available for calculating the critical compressive stress at room temperature can also be used at elevated temperatures if the applicable compressive stress-strain curve for the material is given.

  13. Energy-dependent branching between fluorescence and singlet exciton dissociation in sexithienyl thin films

    NASA Astrophysics Data System (ADS)

    Dippel, O.; Brandl, V.; Bässler, H.; Danieli, R.; Zamboni, R.; Taliani, C.

    1993-12-01

    The fluorescence yield of thin films of sexithienyl drops rapidly above the S 1←S 0 absorption edge while the yield of photocarrier generation increases simultaneously. This unusual behavior of a molecular solid is interpreted in terms of an energy-dependent branching between fluorescence and dissociation of a singlet excitation into a weakly bound electron—hole pair. This is shown to be a characteristic feature of a disordered system in which the energy levels of both neutral and charged excitations are subject to inhomogeneous broadening. In T6 the latter arises from torsional displacement of the thienylene moities.

  14. Location of the low-energy 1Ag state in a polythiophene oligomer by two-photon absorption spectroscopy: α-sexithienyl

    NASA Astrophysics Data System (ADS)

    Periasamy, N.; Danieli, R.; Ruani, G.; Zamboni, R.; Taliani, C.

    1992-02-01

    The two-photon excitation spectrum in polycrystalline α-sexithienyl (T6) thin films has been investigated at 4.2 K in the spectral range between 910 and 1180 nm of the fundamental laser radiation. The intense two-photon absorption band at 18 350 cm-1 is assigned to the 21Ag exciton band origin. The comparison of the one-photon and two-photon excitation spectra shows that the lowest ``gerade'' exciton level lies at 898 cm-1 above the lowest one-photon-allowed 1 2Bu exciton level.

  15. C type murine leukaemia virus particles in tetraparental AKR↔CBA chimaeras

    PubMed Central

    Wills, E. J.; Tuffrey, Maureen; Barnes, R. D.

    1975-01-01

    The incidence of lymphomas in a group of tetraparental AKR ↔ CBA/H-T6 mouse chimaeras derived by early embryo aggregation was less than that of the high leukaemic parental AKR strain. Earlier evidence had shown that the delay in onset and lower incidence of lymphomas in these chimaeras was not due to the absence of AKR cells. We report here that loss of the oncogenic virus carried by the AKR was also unlikely to explain the apparent lymphoma resistance of the chimaeras, since large numbers of C type virus particles were present in their tissues, usually in amounts comparable with the AKR. ImagesFIG. 1FIG. 2

  16. Hypervelocity impact testing of non-metallic materials

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.

    1990-01-01

    A comparative analysis of impact damage in composite and ceramic specimens and in geometrically similar aluminum specimens is performed to determine the advantages and disadvantages of employing certain composite and ceramic materials in the design of structural wall systems for long-duration spacecraft. A similar analysis of the damage in single panel lexan and multi-plane glass windows shows that glass window systems are rather resilent under hypervelocity impact loadings. It is concluded that thin Kevlar 49, IM6/3501-6 graphite/epoxy, and alumina panels offer no advantage over equivalent aluminum 6061-T6 panels in reducing the penetration threat of hypervelocity projectiles.

  17. Cracking associated with micrometeoroid impact craters in anodized aluminum alloy clamps on LDEF

    NASA Technical Reports Server (NTRS)

    Murr, Lawrence E.; Niou, Chorng S.; Quinones, Stella; Murr, Kyle S.

    1992-01-01

    The Long Duration Exposure Facility (LDEF) is a reusable hollow-cylindrical satellite sustaining a total of 57 different experiments. The 130 sq m of spacecraft surface area included anodized 6061-T6 Al alloy bay frames and clamps for holding experiment trays in the bay areas. Attention is presently given to the micrometeoroid impact crater features observed on two tray clamps recovered from the LDEF leading-edge locations. It is found that even very subtle surface modifications in structural alloy anodizing can influence micrometeoroid impact crater cracking, notable radial cracking due to the ejecta-rim of the impact craters.

  18. Electron beam weld development on a Filter Pack Assembly

    NASA Astrophysics Data System (ADS)

    Dereskiewicz, J. P.

    1994-06-01

    A continuous electron beam welding procedure was developed to replace the manual gas tungsten arc welding procedure on the Filter Pack Assembly. A statistical study was used to evaluate the feasibility of electron beam welding 6061-T6 aluminum covers to A356 cast weldments throughout the joint tolerance range specified on product drawings. Peak temperature exposures were not high enough to degrade the heat sensitive electrical components inside the cast weldment. Actual weldments with alodine coating on the weld joint area were successfully cleaned using a nonmetallic fiberglass brush cleaning method.

  19. Spectral karyotyping reveals a comprehensive karyotype in an adult acute lymphoblastic leukemia

    PubMed Central

    Guo, Bo; Zhu, Hong Li; Li, Su Xia; Lu, Xue Chun; Fan, Hui; Da, Wan Ming

    2012-01-01

    Cytogenetic abnormalities are frequently detected in patients with acute lymphoblastic leukemia (ALL). Comprehensive karyotype was related to poor prognosis frequently in ALL. We present a comprehensive karyotype in an adult ALL by spectral karyotyping (SKY) and R-banding. SKY not only confirmed the abnormalities previously seen by R-banding but also improved comprehensive karyotype analysis with the following result 47,XY,+9, ins(1;5)(q23;q23q34) t(6;7)(q23;p13). Our report demonstrated that SKY is able to provide more information accurately for prediction of disease prognosis in adult ALL with comprehensive karyotype. PMID:27298606

  20. Segmental neurofibromatosis type 1 (NF1) associated with Cobb syndrome: case report.

    PubMed

    Pascual-Castroviejo, I; Pascual-Pascual, S-I; Viaño, J

    2008-12-01

    We present a 3-month-old girl who showed segmental NF1 and Cobb syndrome. She has a cutaneous vascular malformation located on the middle T (4)-T (6) region superimposed on a giant cutaneous café-au-lait spot. Magnetic resonance arteriography (MRA) revealed bilateral renal artery stenosis, extensive hypertrophy of the spinal epidural venous plexus, coarctation and tubular hypoplasia of the aortic arch and proximal portion of descending aorta. To the best of our knowledge the association of both neurocutaneous disorders has not being previously described. PMID:19568998