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

  1. Advanced Colloids Experiment (Temperature Controlled) - ACE-T6

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Sicker, Ronald J.; Bailey, Kelly; Eustace, John; Lynch, Matthew

    2017-01-01

    Increment 53 - 54 Science Symposium presentation of Advanced Colloids Experiment (ACE-T6) to RPO. The purpose of this event is for Principal Investigators to present their science objectives, testing approach, and measurement methods to agency scientists, managers, and other investigators.

  2. Advanced Colloids Experiment (Temperature Controlled) - ACE-T6

    NASA Technical Reports Server (NTRS)

    Meyer, William V.; Sicker, Ron; Bailey, Kelly; Eustace, John; Abbott-Hearn, Amber; Lynch, Matthew

    2016-01-01

    Increment 51 - 52 Science Symposium presentation of Advanced Colloids Experiment (ACE-T6) to RPO. The purpose of this event is for Principal Investigators to present their science objectives, testing approach, and measurement methods to agency scientists, managers, and other investigators.

  3. 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.

  4. Formability Evaluation of Aluminum Alloy 6061-T6 Sheet at Room and Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Chen, Zhu; Fang, Gang; Zhao, Jia-Qing

    2017-09-01

    The formability of aluminum alloy 6061-T6 sheet was evaluated, and the effects of temperature and strain rate on the formability were analyzed. Uniaxial tension tests and Nakajima tests were conducted at room temperature to obtain the constitutive parameters of AA 6061-T6 and establish the forming limit diagram (FLD), respectively. Moreover, uniaxial tension tests were performed at the temperatures ranging between 180 and 380 °C and the strain rates ranging between 0.0005 and 0.05 s-1, and the constitutive equations of AA 6061-T6 were established. Nakajima tests at temperature 330 °C and two forming speeds (15 and 150 mm/min) were carried out to evaluate the formability of AA6061-T6 at elevated temperatures. In consequence, FLDs under different forming conditions were established and compared. Experimental results showed that the forming limit of AA 6061-T6 increased with the increasing temperature and the decreasing forming speed. The present investigation presented the formability of AA 6061-T6 under different forming conditions, which provided a guidance to design the warm/hot forming of AA 6061 sheet. The FLDs and constitutive equations established through these experiments will be used to predict the forming defects in the forming process design.

  5. A Visual Assay to Monitor T6SS-mediated Bacterial Competition

    PubMed Central

    Hachani, Abderrahman; Lossi, Nadine S.; Filloux, Alain

    2013-01-01

    Type VI secretion systems (T6SSs) are molecular nanomachines allowing Gram-negative bacteria to transport and inject proteins into a wide variety of target cells1,2. The T6SS is composed of 13 core components and displays structural similarities with the tail-tube of bacteriophages3. The phage uses a tube and a puncturing device to penetrate the cell envelope of target bacteria and inject DNA. It is proposed that the T6SS is an inverted bacteriophage device creating a specific path in the bacterial cell envelope to drive effectors and toxins to the surface. The process could be taken further and the T6SS device could perforate other cells with which the bacterium is in contact, thus injecting the effectors into these targets. The tail tube and puncturing device parts of the T6SS are made with Hcp and VgrG proteins, respectively4,5. The versatility of the T6SS has been demonstrated through studies using various bacterial pathogens. The Vibrio cholerae T6SS can remodel the cytoskeleton of eukaryotic host cells by injecting an "evolved" VgrG carrying a C-terminal actin cross-linking domain6,7. Another striking example was recently documented using Pseudomonas aeruginosa which is able to target and kill bacteria in a T6SS-dependent manner, therefore promoting the establishment of bacteria in specific microbial niches and competitive environment8,9,10. In the latter case, three T6SS-secreted proteins, namely Tse1, Tse2 and Tse3 have been identified as the toxins injected in the target bacteria (Figure 1). The donor cell is protected from the deleterious effect of these effectors via an anti-toxin mechanism, mediated by the Tsi1, Tsi2 and Tsi3 immunity proteins8,9,10. This antimicrobial activity can be monitored when T6SS-proficient bacteria are co-cultivated on solid surfaces in competition with other bacterial species or with T6SS-inactive bacteria of the same species8,11,12,13. The data available emphasized a numerical approach to the bacterial competition assay

  6. A visual assay to monitor T6SS-mediated bacterial competition.

    PubMed

    Hachani, Abderrahman; Lossi, Nadine S; Filloux, Alain

    2013-03-20

    Type VI secretion systems (T6SSs) are molecular nanomachines allowing Gram-negative bacteria to transport and inject proteins into a wide variety of target cells(1,2). The T6SS is composed of 13 core components and displays structural similarities with the tail-tube of bacteriophages(3). The phage uses a tube and a puncturing device to penetrate the cell envelope of target bacteria and inject DNA. It is proposed that the T6SS is an inverted bacteriophage device creating a specific path in the bacterial cell envelope to drive effectors and toxins to the surface. The process could be taken further and the T6SS device could perforate other cells with which the bacterium is in contact, thus injecting the effectors into these targets. The tail tube and puncturing device parts of the T6SS are made with Hcp and VgrG proteins, respectively(4,5). The versatility of the T6SS has been demonstrated through studies using various bacterial pathogens. The Vibrio cholerae T6SS can remodel the cytoskeleton of eukaryotic host cells by injecting an "evolved" VgrG carrying a C-terminal actin cross-linking domain(6,7). Another striking example was recently documented using Pseudomonas aeruginosa which is able to target and kill bacteria in a T6SS-dependent manner, therefore promoting the establishment of bacteria in specific microbial niches and competitive environment(8,9,10). In the latter case, three T6SS-secreted proteins, namely Tse1, Tse2 and Tse3 have been identified as the toxins injected in the target bacteria (Figure 1). The donor cell is protected from the deleterious effect of these effectors via an anti-toxin mechanism, mediated by the Tsi1, Tsi2 and Tsi3 immunity proteins(8,9,10). This antimicrobial activity can be monitored when T6SS-proficient bacteria are co-cultivated on solid surfaces in competition with other bacterial species or with T6SS-inactive bacteria of the same species(8,11,12,13). The data available emphasized a numerical approach to the bacterial

  7. 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

  8. Fatigue Reliability Analysis of 6156-T6 Riveted Joints based on Detail Fatigue Rating

    NASA Astrophysics Data System (ADS)

    Chen, An; Yang, Jun; Zhang, Kan; Zhang, Haiying

    2017-11-01

    The fatigue behavior of two kinds of riveted joints 6156-T6 aluminum alloy structures was experimentally investigated. The detail fatigue rating (DFR) values of 6156-T6 is calculated based on statistical analysis of fatigue tests. The fatigue crack initiation and propagation behavior are examined using scanning electron microscopy. The results show that DFR value of 6156-T6 aluminum alloy with riveted lap joints is 97.81MPa, and the DFR value of rivet-filled countersink hole structure is 168.39MPa. The crack initiation sites occurred at the vicinity of the fastener hole in all specimens. The fatigue striations were uniformly spaced in the region of stable crack growth.

  9. Trichinella T6 and Trichinella nativa in Wolverines (Gulo gulo) from Nunavut, Canada.

    PubMed

    Reichard, Mason V; Torretti, Luigi; Snider, Timothy A; Garvon, Jason M; Marucci, Gianluca; Pozio, Edoardo

    2008-08-01

    Infection of Trichinella spp. is common among animals in the Canadian Arctic. We determined the prevalence of Trichinella spp. infection in wolverines (Gulo gulo) from Nunavut, Canada. Diaphragms from 41 wolverines were examined by artificial digestion. Trichinella spp. larvae were detected in 36 (87.8%) examined animals. Trichinella T6 was detected in 33 (91.7%), Trichinella nativa in only one (2.8%), and a mixed Trichinella T6 and T. nativa infections were detected in two (5.6%) wolverines. This is the first report of Trichinella spp. infection in wolverines from Nunavut and the first report of sympatric Trichinella T6 and T. nativa in any host. The high prevalence of Trichinella spp. infection in combination with the natural history of wolverines suggests that the mustelid may be a key species in the natural cycle of these parasites in Arctic and Subarctic areas.

  10. Coarsening of AA6013-T6 Precipitates During Sheet Warm Forming Applications

    NASA Astrophysics Data System (ADS)

    Di Ciano, M.; DiCecco, S.; Esmaeili, S.; Wells, M. A.; Worswick, M. J.

    2018-01-01

    The use of warm forming for AA6xxx-T6 sheet is of interest to improve its formability; however, the effect warm forming may have on the coarsening of precipitates and the mechanical strength of these sheets has not been well studied. In this research, the coarsening behavior of AA6013-T6 precipitates has been explored, in the temperature range of 200-300 °C, and time of 30 s up to 50 h. Additionally, the effect of warm deformation on coarsening behavior was explored using: (1) simulated warm forming tests in a Gleeble thermo-mechanical simulator and (2) bi-axial warm deformation tests. Using a strong obstacle model to describe the yield strength (YS) evolution of the AA6013-T6 material, and a Lifshitz, Slyozov, and Wagner (LSW) particle coarsening law to describe the change in precipitate size with time, the coarsening kinetics were modeled for this alloy. The coarsening kinetics in the range of 220-300 °C followed a trend similar to that previously found for AA6111 for the 180-220 °C range. There was strong evidence that coarsening kinetics were not altered due to warm deformation above 220 °C. For warm forming between 200 and 220 °C, the YS of the AA6013-T6 material increased slightly, which could be attributed to strain hardening during warm deformation. Finally, a non-isothermal coarsening model was used to assess the potential reduction in the YS of AA6013-T6 for practical processing conditions related to auto-body manufacturing. The model calculations showed that 90% of the original AA6013-T6 YS could be maintained, for warm forming temperatures up to 280 °C, if the heating schedule used to get the part to the warm forming temperature was limited to 1 min.

  11. 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.

  12. Multi-Objective Optimization of Friction Stir Welding Process Parameters of AA6061-T6 and AA7075-T6 Using a Biogeography Based Optimization Algorithm.

    PubMed

    Tamjidy, Mehran; Baharudin, B T Hang Tuah; Paslar, Shahla; Matori, Khamirul Amin; Sulaiman, Shamsuddin; Fadaeifard, Firouz

    2017-05-15

    The development of Friction Stir Welding (FSW) has provided an alternative approach for producing high-quality welds, in a fast and reliable manner. This study focuses on the mechanical properties of the dissimilar friction stir welding of AA6061-T6 and AA7075-T6 aluminum alloys. The FSW process parameters such as tool rotational speed, tool traverse speed, tilt angle, and tool offset influence the mechanical properties of the friction stir welded joints significantly. A mathematical regression model is developed to determine the empirical relationship between the FSW process parameters and mechanical properties, and the results are validated. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, elongation, and minimum hardness in the heat affected zone (HAZ), a metaheuristic, multi objective algorithm based on biogeography based optimization is proposed. The Pareto optimal frontiers for triple and dual objective functions are obtained and the best optimal solution is selected through using two different decision making techniques, technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon's entropy.

  13. Multi-Objective Optimization of Friction Stir Welding Process Parameters of AA6061-T6 and AA7075-T6 Using a Biogeography Based Optimization Algorithm

    PubMed Central

    Tamjidy, Mehran; Baharudin, B. T. Hang Tuah; Paslar, Shahla; Matori, Khamirul Amin; Sulaiman, Shamsuddin; Fadaeifard, Firouz

    2017-01-01

    The development of Friction Stir Welding (FSW) has provided an alternative approach for producing high-quality welds, in a fast and reliable manner. This study focuses on the mechanical properties of the dissimilar friction stir welding of AA6061-T6 and AA7075-T6 aluminum alloys. The FSW process parameters such as tool rotational speed, tool traverse speed, tilt angle, and tool offset influence the mechanical properties of the friction stir welded joints significantly. A mathematical regression model is developed to determine the empirical relationship between the FSW process parameters and mechanical properties, and the results are validated. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, elongation, and minimum hardness in the heat affected zone (HAZ), a metaheuristic, multi objective algorithm based on biogeography based optimization is proposed. The Pareto optimal frontiers for triple and dual objective functions are obtained and the best optimal solution is selected through using two different decision making techniques, technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon’s entropy. PMID:28772893

  14. 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.

  15. 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.

  16. Feasibility Study on the Replacement or Upgrade of the T-6 Track Research Vehicle.

    DOT National Transportation Integrated Search

    1998-03-01

    This feasibility and cost study concluded that the FRA's aging T-6 can be replaced with a new state-of-the-art research platform costing approximately 3.5 million. The new, Track Research Instrumentation Platform (TRIP) is envisioned as a laboratory ...

  17. 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

  18. Corrosion Fatigue Crack Growth Behavior at Notched Hole in 7075-T6 Under Biaxial and Uniaxial Fatigue with Different Phases

    DTIC Science & Technology

    2015-09-17

    CORROSION FATIGUE CRACK GROWTH BEHAVIOR AT NOTCHED HOLE IN 7075-T6 UNDER BIAXIAL AND UNIAXIAL FATIGUE WITH DIFFERENT PHASES...CORROSION FATIGUE CRACK GROWTH BEHAVIOR AT NOTCHED HOLE IN 7075-T6 UNDER BIAXIAL AND UNIAXIAL FATIGUE WITH DIFFERENT PHASES THESIS...UNLIMITED AFIT-ENY-MS-15-S-065 CORROSION FATIGUE CRACK GROWTH BEHAVIOR AT NOTCHED HOLE IN 7075-T6 UNDER BIAXIAL AND UNIAXIAL FATIGUE WITH

  19. Morphometric study of the T6 vertebra and its three ossification centers in the human fetus.

    PubMed

    Szpinda, Michał; Baumgart, Mariusz; Szpinda, Anna; Woźniak, Alina; Mila-Kierzenkowska, Celestyna; Dombek, Małgorzata; Kosiński, Adam; Grzybiak, Marek

    2013-12-01

    Knowledge on the normative growth of the spine is critical in the prenatal detection of its abnormalities. We aimed to study the size of T6 vertebra in human fetuses with the crown-rump length of 115-265 mm. Using the methods of computed tomography (Biograph mCT), digital image analysis (Osirix 3.9) and statistics, the normative growth of the T6 vertebral body and the three ossification centers of T6 vertebra in 55 spontaneously aborted human fetuses (27 males, 28 females) aged 17-30 weeks were studied. Neither male-female nor right-left significant differences were found. The height, transverse, and sagittal diameters of the T6 vertebral body followed natural logarithmic functions as y = -4.972 + 2.732 × ln(age) ± 0.253 (R (2) = 0.72), y = -14.862 + 6.426 × ln(age) ± 0.456 (R (2) = 0.82), and y = -10.990 + 4.982 × ln(age) ± 0.278 (R (2) = 0.89), respectively. Its cross-sectional area (CSA) rose proportionately as y = -19.909 + 1.664 × age ± 2.033 (R (2) = 0.89), whereas its volumetric growth followed the four-degree polynomial function y = 19.158 + 0.0002 × age(4) ± 7.942 (R (2) = 0.93). The T6 body ossification center grew logarithmically in both transverse and sagittal diameters as y = -14.784 + 6.115 × ln(age) ± 0.458 (R (2) = 0.81) and y = -12.065 + 5.019 × ln(age) ± 0.315 (R (2) = 0.87), and proportionately in both CSA and volume like y = -15.591 + 1.200 × age ± 1.470 (R (2) = 0.90) and y = -22.120 + 1.663 × age ± 1.869 (R (2) = 0.91), respectively. The ossification center-to-vertebral body volume ratio was gradually decreasing with age. On the right and left, the neural ossification centers revealed the following models: y = -15.188 + 6.332 × ln(age) ± 0.629 (R (2) = 0.72) and y = -15.991 + 6.600 × ln(age) ± 0.629 (R (2) = 0.74) for length, y = -6.716 + 2.814 × ln(age) ± 0.362 (R (2) = 0.61) and y = -7.058 + 2

  20. 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

    2015-01-01

    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

  1. Mechanical characterization and fracture toughness of electroplated cadmium coating of Al -Zn alloy, T6

    NASA Astrophysics Data System (ADS)

    Mohan Kumar, S.; Ravi Kumar, V.; Shashi Kumar, M. E.; Govindaraju, H. K.

    2017-07-01

    Fracture toughness, Hardness and Tensile Strength of the Aluminum alloy 7075-T6 coated with Cadmium with varying thickness of 10µ and 20µ were investigated. Electroplating Cadmium coating process gives excellent corrosion resistance, provides low coefficient of friction which increases the surface hardness of the material. It also provides a uniform and dense coating, in many cases, maintains surface finish as it was before plating. The specimens prepared in line with ASTM E-8M and E-399 standard were subjected to various tests. The results shows thatthe hardness of the EC coted specimens has increased by 10% and increases with increase in thickness, butthe thicker the EC coating, more brittle is the material. The Ultimate Tensile Strength also increased by 5% compared to the uncoated counterpart. There was a steep increase in plain strain fracture toughness with the increase in the coating thickness for the Aluminum 7075-T6 alloy in TL orientation. The crack growth was Unstable due to the strong adhesion between the EC coating and the alloy.

  2. 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.

  3. 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.

  4. The abp gene in Geobacillus stearothermophilus T-6 encodes a GH27 β-L-arabinopyranosidase.

    PubMed

    Salama, Rachel; Alalouf, Onit; Tabachnikov, Orly; Zolotnitsky, Gennady; Shoham, Gil; Shoham, Yuval

    2012-07-30

    In this study we demonstrate that the abp gene in Geobacillus stearothermophilus T-6 encodes a family 27 glycoside hydrolase β-L-arabinopyranosidase. The catalytic constants towards the chromogenic substrate pNP-β-L-arabinopyranoside were 0.8±0.1 mM, 6.6±0.3 s(-1), and 8.2±0.3 s(-1) mM(-1) for K(m), k(cat) and k(cat)/K(m), respectively. (13)C NMR spectroscopy unequivocally showed that Abp is capable of removing β-L-arabinopyranose residues from the natural arabino-polysaccharide, larch arabinogalactan. Most family 27 enzymes are active on galactose and contain a conserved Asp residue, whereas in Abp this residue is Ile67, which shifts the specificity of the enzyme towards arabinopyranoside. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  5. 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.

  6. Precipitation-Induced Grain Growth Simulation of Friction-Stir-Welded AA6082-T6

    NASA Astrophysics Data System (ADS)

    Wu, Q.; Zhang, Z.

    2017-05-01

    Friction stir welding of AA6082-T6 with different welding parameters is simulated by computational fluid dynamics model. Monte Carlo method is further used to simulate the grain growth with consideration of the precipitation effects. The comparison with experimental observations can validate the proposed grain growth model with the precipitate effects. Results indicate that the final grain size can be increased by 39.7% in the nugget zone when the volume fraction of precipitation is decreased from 0.8 to 0.2% after welding. Both the grain growth speed and the final grain size on the top surface are higher than the bottom surface. The increase in the welding temperature caused by the increase in the rotation speeds or the axial forces can lead to lower volume fractions of precipitations and then lead to larger grain sizes.

  7. Numerical and experimental investigation of the formability of AA6013-T6

    NASA Astrophysics Data System (ADS)

    DiCecco, S.; Di Ciano, M.; Butcher, C.; Worswick, M.

    2017-09-01

    AA6013 is an age-hardenable, aluminum alloy with the potential for structural applications in weight-sensitive automotive components. The alloy is at peak strength in the T6 temper, but exhibits relatively low room temperature formability. In an effort to avoid costly post-forming heat-treatments, warm forming of the AA6013 in the T6 temper is investigated in the current work. The experimental formability of the alloy is characterized from room temperature to 250°C through limiting dome height (LDH) tests with a Nakazima hemispherical punch and in-situ stereoscopic digital image correlation (DIC) strain measurement. A forming limit diagram (FLD) is generated from the application of a curvature-based necking criterion to the elevated temperature LDH test results. The evolution of the strain distribution prior to necking is explored using models of the plane strain LDH tests at room temperature and 200°C. At 200°C, strain rate effects are explored relative to the local temporal strain evolution. Modelling efforts include development of a Barlat Yld2000 yield surface to capture the anisotropy of the alloy and use of experimentally obtained isothermal flow-stress curves. The effects of different tensile gage lengths on flow-stress and yield surface calibration for warm tensile testing are discussed. The room temperature model was found to accurately depict the thinning strain distribution consistent with the “safe” thinning strain distribution at room temperature. At 200°C, it is shown that the temporal strain evolution is strongly influenced by strain-rate effects.

  8. 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

  9. Subtle variation within conserved effector operon gene products contributes to T6SS-mediated killing and immunity

    PubMed Central

    Hershey, Haley L.; Miller, Jessa E.

    2017-01-01

    Type VI secretion systems (T6SS) function to deliver lethal payloads into target cells. Many studies have shown that protection against a single, lethal T6SS effector protein requires a cognate antidote immunity protein, both of which are often encoded together in a two-gene operon. The T6SS and an effector-immunity pair is sufficient for both killing and immunity. HereIn this paper we describe a T6SS effector operon that differs from conventional effector-immunity pairs in that eight genes are necessary for lethal effector function, yet can be countered by a single immunity protein. In this study, we investigated the role that the PefE T6SS immunity protein plays in recognition between two strains harboring nearly identical effector operons. Interestingly, despite containing seven of eight identical effector proteins, the less conserved immunity proteins only provided protection against their native effectors, suggesting that specificity and recognition could be dependent on variation within an immunity protein and one effector gene product. The variable effector gene product, PefD, is encoded upstream from pefE, and displays toxic activity that can be countered by PefE independent of T6SS-activity. Interestingly, while the entire pef operon was necessary to exert toxic activity via the T6SS in P. mirabilis, production of PefD and PefE alone was unable to exert this effector activity. Chimeric PefE proteins constructed from two P. mirabilis strains were used to localize immunity function to three amino acids. A promiscuous immunity protein was created using site-directed mutagenesis to change these residues from one variant to another. These findings support the notion that subtle differences between conserved effectors are sufficient for T6SS-mediated kin discrimination and that PefD requires additional factors to function as a T6SS-dependent effector. PMID:29155899

  10. The Glucuronic Acid Utilization Gene Cluster from Bacillus stearothermophilus T-6

    PubMed Central

    Shulami, Smadar; Gat, Orit; Sonenshein, Abraham L.; Shoham, Yuval

    1999-01-01

    A λ-EMBL3 genomic library of Bacillus stearothermophilus T-6 was screened for hemicellulolytic activities, and five independent clones exhibiting β-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 β-xylosidase; and a putative 15.5-kb-long transcriptional unit, consisting of 12 genes involved in the utilization of α-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-α-(4-O-methyl-α-d-glucuronosyl)-xylotriose] (MeGlcUAXyl3). The following two genes code for an intracellular α-glucuronidase (aguA) and a β-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

  11. Si doped T6 carbon structure as an anode material for Li-ion batteries: An ab initio study

    PubMed Central

    Rajkamal, A.; Kumar, E. Mathan; Kathirvel, V.; Park, Noejung; Thapa, Ranjit

    2016-01-01

    First-principles calculations are performed to identify the pristine and Si doped 3D metallic T6 carbon structure (having both sp2 and sp3 type hybridization) as a new carbon based anode material. The π electron of C2 atoms (sp2 bonded) forms an out of plane network that helps to capture the Li atom. The highest Li storage capacity of Si doped T6 structure with conformation Li1.7Si1C5 produces theoretical specific capacity of 632 mAh/g which substantially exceeding than graphite. Also, open-circuit voltage (OCV) with respect to Li metal shows large negative when compared to the pristine T6 structure. This indicates modifications in terms of chemical properties are required in anode materials for practical application. Among various doped (Si, Ge, Sn, B, N) configuration, Si doped T6 structure provides a stable positive OCV for high Li concentrations. Likewise, volume expansion study also shows Si doped T6 structure is more stable with less pulverization and substantial capacity losses in comparison with graphite and silicon as an anode materials. Overall, mixed hybridized (sp2 + sp3) Si doped T6 structure can become a superior anode material than present sp2 hybridized graphite and sp3 hybridized Si structure for modern Lithium ion batteries. PMID:27892532

  12. Si doped T6 carbon structure as an anode material for Li-ion batteries: An ab initio study.

    PubMed

    Rajkamal, A; Kumar, E Mathan; Kathirvel, V; Park, Noejung; Thapa, Ranjit

    2016-11-28

    First-principles calculations are performed to identify the pristine and Si doped 3D metallic T6 carbon structure (having both sp 2 and sp 3 type hybridization) as a new carbon based anode material. The π electron of C 2 atoms (sp 2 bonded) forms an out of plane network that helps to capture the Li atom. The highest Li storage capacity of Si doped T6 structure with conformation Li 1.7 Si 1 C 5 produces theoretical specific capacity of 632 mAh/g which substantially exceeding than graphite. Also, open-circuit voltage (OCV) with respect to Li metal shows large negative when compared to the pristine T6 structure. This indicates modifications in terms of chemical properties are required in anode materials for practical application. Among various doped (Si, Ge, Sn, B, N) configuration, Si doped T6 structure provides a stable positive OCV for high Li concentrations. Likewise, volume expansion study also shows Si doped T6 structure is more stable with less pulverization and substantial capacity losses in comparison with graphite and silicon as an anode materials. Overall, mixed hybridized (sp 2  + sp 3 ) Si doped T6 structure can become a superior anode material than present sp 2 hybridized graphite and sp 3 hybridized Si structure for modern Lithium ion batteries.

  13. In vitro biosynthesis of a universal t6A tRNA modification in Archaea and Eukarya

    PubMed Central

    Perrochia, Ludovic; Crozat, Estelle; Hecker, Arnaud; Zhang, Wenhua; Bareille, Joseph; Collinet, Bruno; van Tilbeurgh, Herman; Forterre, Patrick

    2013-01-01

    N6-threonylcarbamoyladenosine (t6A) is a modified nucleotide found in all transfer RNAs (tRNAs) decoding codons starting with adenosine. Its role is to facilitate codon–anticodon pairing and to prevent frameshifting during protein synthesis. Genetic studies demonstrated that two universal proteins, Kae1/YgjD and Sua5/YrdC, are necessary for t6A synthesis in Saccharomyces cerevisiae and Escherichia coli. In Archaea and Eukarya, Kae1 is part of a conserved protein complex named kinase, endopeptidase and other proteins of small size (KEOPS), together with three proteins that have no bacterial homologues. Here, we reconstituted for the first time an in vitro system for t6A modification in Archaea and Eukarya, using purified KEOPS and Sua5. We demonstrated binding of tRNAs to archaeal KEOPS and detected two distinct adenosine triphosphate (ATP)-dependent steps occurring in the course of the synthesis. Our data, together with recent reconstitution of an in vitro bacterial system, indicated that t6A cannot be catalysed by Sua5/YrdC and Kae1/YgjD alone but requires accessory proteins that are not universal. Remarkably, we observed interdomain complementation when bacterial, archaeal and eukaryotic proteins were combined in vitro, suggesting a conserved catalytic mechanism for the biosynthesis of t6A in nature. These findings shed light on the reaction mechanism of t6A synthesis and evolution of molecular systems that promote translation fidelity in present-day cells. PMID:23258706

  14. In vitro biosynthesis of a universal t6A tRNA modification in Archaea and Eukarya.

    PubMed

    Perrochia, Ludovic; Crozat, Estelle; Hecker, Arnaud; Zhang, Wenhua; Bareille, Joseph; Collinet, Bruno; van Tilbeurgh, Herman; Forterre, Patrick; Basta, Tamara

    2013-02-01

    N(6)-threonylcarbamoyladenosine (t(6)A) is a modified nucleotide found in all transfer RNAs (tRNAs) decoding codons starting with adenosine. Its role is to facilitate codon-anticodon pairing and to prevent frameshifting during protein synthesis. Genetic studies demonstrated that two universal proteins, Kae1/YgjD and Sua5/YrdC, are necessary for t(6)A synthesis in Saccharomyces cerevisiae and Escherichia coli. In Archaea and Eukarya, Kae1 is part of a conserved protein complex named kinase, endopeptidase and other proteins of small size (KEOPS), together with three proteins that have no bacterial homologues. Here, we reconstituted for the first time an in vitro system for t(6)A modification in Archaea and Eukarya, using purified KEOPS and Sua5. We demonstrated binding of tRNAs to archaeal KEOPS and detected two distinct adenosine triphosphate (ATP)-dependent steps occurring in the course of the synthesis. Our data, together with recent reconstitution of an in vitro bacterial system, indicated that t(6)A cannot be catalysed by Sua5/YrdC and Kae1/YgjD alone but requires accessory proteins that are not universal. Remarkably, we observed interdomain complementation when bacterial, archaeal and eukaryotic proteins were combined in vitro, suggesting a conserved catalytic mechanism for the biosynthesis of t(6)A in nature. These findings shed light on the reaction mechanism of t(6)A synthesis and evolution of molecular systems that promote translation fidelity in present-day cells.

  15. Microstructure, hardness profile and tensile strength in welds of AA6013 T6 extrusions

    SciTech Connect

    Guitterez, L.A.; Neye, G.; Zschech, E.

    1996-04-01

    Alloy AA6013 is easily welded by conventional arc welding processes as well as by high-energy-density processes. However, some physical properties, which are inherent to all aluminum alloys, have to be considered during welding. In comparison to steel, the high thermal conductivity of aluminum alloys requires the use of higher heat input for welding. This is realized by a greater welding current during GTAW of aluminum alloys. One of the main problems associated with LBW of aluminum alloys is the high surface reflectivity. In particular, the threshold intensity for the development of a keyhole is much higher for aluminum than formore » steel. Finally, aluminum alloys, and particularly the heat-treatable alloys, are sensitive to weld cracking. This phenomenon can be avoided by proper filler and base metal alloy selection and adequate filler metal dilution. In order to improve the mechanical integrity of Al-Mg-Si weldments, it would be desirable to study the microstructure of the FZ and of the HAZ, as well as the residual stress distribution. The present study was performed in order to show differences in microstructure, hardness profile and tensile strength of gas tungsten arc (GTA) and laser beam (LB) welded AA6013-T6 extrusions. In addition, grain boundary liquations and hot tearing are discussed.« less

  16. 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.

  17. Cyclic Elastoplastic Performance of Aluminum 7075-T6 Under Strain- and Stress-Controlled Loading

    NASA Astrophysics Data System (ADS)

    Agius, Dylan; Wallbrink, Chris; Kourousis, Kyriakos I.

    2017-12-01

    Elastoplastic investigations of aerospace aluminum are important in the development of an understanding of the possible cyclic transient effects and their contribution to the material performance under cyclic loading. Cyclic plasticity can occur in an aerospace aluminum component or structure depending on the loading conditions and the presence of external and internal discontinuities. Therefore, it is vital that the cyclic transient effects of aerospace aluminum are recognized and understood. This study investigates experimentally the cyclic elastoplastic performance of aluminum 7075-T6 loaded in symmetric strain control, and asymmetric stress and strain control. A combination of cyclic hardening and softening was noticed from high strain amplitude symmetric strain-controlled tests and at low stress amplitude asymmetric stress-controlled tests. From asymmetric strain control results, the extent of mean stress relaxation depended on the size of the strain amplitude. Additionally, saturation of the ratcheting strain (plastic shakedown) was also found to occur during asymmetric stress control tests. The experimental results were further analyzed using published microstructure research from the past two decades to provide added explanation of the micro-mechanism contribution to the cyclic transient behavior.

  18. 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.

  19. Modeling the effect of laser heating on the strength and failure of 7075-T6 aluminum

    DOE PAGES

    Florando, J. N.; Margraf, J. D.; Reus, J. F.; ...

    2015-06-06

    The effect of rapid laser heating on the response of 7075-T6 aluminum has been characterized using 3-D digital image correlation and a series of thermocouples. The experimental results indicate that as the samples are held under a constant load, the heating from the laser profile causes non-uniform temperature and strain fields, and the strain-rate increases dramatically as the sample nears failure. Simulations have been conducted using the LLNL multi-physics code ALE3D, and compared to the experiments. The strength and failure of the material was modeled using the Johnson–Cook strength and damage models. Here, in order to capture the response, amore » dual-condition criterion was utilized which calibrated one set of parameters to low temperature quasi-static strain rate data, while the other parameter set is calibrated to high temperature high strain rate data. The thermal effects were captured using temperature dependent thermal constants and invoking thermal transport with conduction, convection, and thermal radiation.« less

  20. 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.

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

    SciTech Connect

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

    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

  2. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Experimental Research on Fatigue Failure for 2219-T6 Aluminum Alloy Friction Stir-Welded Joints

    NASA Astrophysics Data System (ADS)

    Sun, Guo-Qin; Niu, Jiang-Pei; Chen, Ya-Jing; Sun, Feng-Yang; Shang, De-Guang; Chen, Shu-Jun

    2017-08-01

    The fatigue experiment was executed for the 2219-T6 aluminum alloy friction stir-welded joints at the rotation speed of 800 r/min and the welding velocity of 150 mm/min. Most fatigue failures occurred in the weld nugget zone (WNZ), the thermo-mechanical affected zone and the nearby areas. The experimental results demonstrated that the sudden hardness gradient increases sites corresponding to the fatigue failure locations. The high-angle grain boundaries with the highest concentration were scattered within the WNZ. The microcracks initiated at the intersection of the soft grains. More than one crack initiation site was observed within the WNZ and the thermo-mechanical affected zone, when the fracture occurred in these areas. The rough surface of the welding area should be one of the main reasons for the fatigue failure occurrence. The fatigue crack growth rate in the WNZ at the first stage was fastest in comparison with the fatigue crack growth rate in the other areas of the joint.

  4. Sensitivity of polycrystal plasticity to slip system kinematic hardening laws for Al 7075-T6

    SciTech Connect

    Hennessey, Conor; Castelluccio, Gustavo M.; McDowell, David L.

    2017-02-01

    The prediction of formation and early growth of microstructurally small fatigue cracks requires use of constitutive models that accurately estimate local states of stress, strain, and cyclic plastic strain. However, few research efforts have attempted to systematically consider the sensitivity of overall cyclic stress-strain hysteresis and higher order mean stress relaxation and plastic strain ratcheting responses introduced by the slip system back-stress formulation in crystal plasticity, even for face centered cubic (FCC) crystal systems. This paper explores the performance of two slip system level kinematic hardening models using a finite element crystal plasticity implementation as a User Material Subroutine (UMAT)more » within ABAQUS, with fully implicit numerical integration. The two kinematic hardening formulations aim to reproduce the cyclic deformation of polycrystalline Al 7075-T6 in terms of both macroscopic cyclic stress-strain hysteresis loop shape, as well as ratcheting and mean stress relaxation under strain- or stress-controlled loading with mean strain or stress, respectively. The first formulation is an Armstrong-Frederick type hardening-dynamic recovery law for evolution of the back stress. This approach is capable of reproducing observed deformation under completely reversed uniaxial loading conditions, but overpredicts the rate of cyclic ratcheting and associated mean stress relaxation. The second formulation corresponds to a multiple back stress Ohno-Wang type hardening law with nonlinear dynamic recovery. The adoption of this back stress evolution law greatly improves the capability to model experimental results for polycrystalline specimens subjected to cycling with mean stress or strain. As a result, the relation of such nonlinear dynamic recovery effects are related to slip system interactions with dislocation substructures.« less

  5. 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

  6. 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.

  7. Sensitivity of polycrystal plasticity to slip system kinematic hardening laws for Al 7075-T6

    SciTech Connect

    Hennessey, Conor; Castelluccio, Gustavo M.; McDowell, David L.

    2017-02-01

    The prediction of formation and early growth of microstructurally small fatigue cracks requires use of constitutive models that accurately estimate local states of stress, strain, and cyclic plastic strain. However, few research efforts have attempted to systematically consider the sensitivity of overall cyclic stress-strain hysteresis and higher order mean stress relaxation and plastic strain ratcheting responses introduced by the slip system back-stress formulation in crystal plasticity, even for face centered cubic (FCC) crystal systems. This paper explores the performance of two slip system level kinematic hardening models using a finite element crystal plasticity implementation as a User Material Subroutine (UMAT) within ABAQUS, with fully implicit numerical integration. The two kinematic hardening formulations aim to reproduce the cyclic deformation of polycrystalline Al 7075-T6 in terms of both macroscopic cyclic stress-strain hysteresis loop shape, as well as ratcheting and mean stress relaxation under strain- or stress-controlled loading with mean strain or stress, respectively. The first formulation is an Armstrong-Frederick type hardening-dynamic recovery law for evolution of the back stress. This approach is capable of reproducing observed deformation under completely reversed uniaxial loading conditions, but overpredicts the rate of cyclic ratcheting and associated mean stress relaxation. The second formulation corresponds to a multiple back stress Ohno-Wang type hardening law with nonlinear dynamic recovery. The adoption of this back stress evolution law greatly improves the capability to model experimental results for polycrystalline specimens subjected to cycling with mean stress or strain. As a result, the relation of such nonlinear dynamic recovery effects are related to slip system interactions with dislocation substructures.

  8. 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

  9. [Effects of blueberry on apoptosis and expression of Bcl-2 and Bax in HSC-T6].

    PubMed

    Lu, Shuang; Cheng, Mingliang; Yang, Demeng; Liu, Yang; Guan, Li; Wu, Jun

    2015-08-18

    To investigate the effects of blueberry on the apoptosis, expression of Bcl-2 and Bax in rat hepatic stellate cell (HSC-T6). 10% blueberry serum at low, middle and high dose, 10% Fu-Fang-Bie-Jia-Ruan-Gan tablet serum and 10% saline serum were prepared by method of serum pharmacology. Subcultured HSC-T6 was divided into saline serum control group, blueberry serum at low, middle, high dose and Fu-Fang-Bie-Jia-Ruan-Gan tablet serum group, and then was respectively incubated at different dose of 10% blueberry serum, 10% Fu-Fang-Bie-Jia-Ruan-Gan tablet serum and 10% saline serum for 72 hours.Apoptosis of HSC-T6 was detected using flow cytometry with annexin V FITC/PI double staining. The expression of Bcl-2 and Bax in HSC-T6 were examined using immunocytochemistry and Western blotting, respectively. There was no significant difference for HSC-T6 Bax protein expression in the low, middle and high dose blueberry serum groups, compared with saline serum control group, respectively.In the high-dose blueberry serum group HSC-T6 early and total apoptosis rate increased significantly compared with the saline serum control group (5.55% ± 0.98% vs 2.53% ± 0.46%, 7.01% ± 1.05% vs 2.96% ± 0.81%, both P<0.05); Bcl-2 protein expression was significantly decreased (A value, 82 ± 35 vs 51 ± 13, P<0.05); Bcl-2/Bax ratio was significantly decreased (0.26 ± 0.02 vs 0.46 ± 0.03, P<0.05); HSC-T6 early and total apoptosis rate, Bcl-2 expression and Bcl-2/Bax ratio in the low and the middle dose blueberry serum group showed no significant difference with the saline serum control group. Blueberry can induce HSC-T6 apoptosis by down-regulating Bcl-2 expression and decreasing the ratio of Bcl-2/Bax in HSC-T6 cells, so it may have potential interference effects on hepatic fibrosis.

  10. 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.

  11. Mechanisms and Characterization of Trichoderma longibrachiatum T6 in Suppressing Nematodes (Heterodera avenae) in Wheat

    PubMed Central

    Zhang, Shuwu; Gan, Yantai; Ji, Weihong; Xu, Bingliang; Hou, Baohong; Liu, Jia

    2017-01-01

    Heterodera avenae is an important soil-borne pathogen that affects field crops worldwide. Chemical nematicides can be used to control the nematode, but they bring toxicity to the environment and human. Trichoderma longibrachiatum has been shown to have the ability to control H. avenae cysts, but detailed microscopic observations and bioassays are lacking. In this study, we used microscopic observations and bioassays to study the effect of T. longibrachiatum T6 (TL6) on the eggs and second stage juveniles (J2s) of H. avenae, and investigate the role of TL6 in inducing the resistance to H. avenae in wheat seedling at physiological and biochemical levels. Microscopic observations recorded that TL6 parasitized on the H. avenae eggs, germinated, and produced a large number of hyphae on the eggs surface at the initial stage, thereafter, the eggs were completely surrounded by dense mycelia and the contents of eggs were lysed at the late stage. Meanwhile, the conidia suspension of TL6 parasitized on the surface of J2s, produced a large number of hyphae that penetrated the cuticle and caused deformation of the nematodes. TL6 at the concentration of 1.5 × 107 conidia ml−1 had the highest rates of parasitism on eggs and J2s, reflected by the highest hatching-inhibition of eggs and the mortality of J2s. In the greenhouse experiments, wheat seedlings treated with TL6 at 1.5 × 107 conidia ml−1 had reduced H. avenae infection, and increased plant growth significantly compared to the control. The cysts and juveniles in soil were reduced by 89.8 and 92.7%, the juveniles and females in roots were reduced by 88.3 and 91.3%, whereas the activity of chitinase and β-1, 3-glucanase, total flavonoids and lignin contents in wheat roots were increased significantly at different stage after inoculation with the eggs and TL6 conidia in comparison to the control. Maximum activity of chitinase and β-1, 3-glucanase were recorded at the 20th and 15th Days after inoculation with TL6 and

  12. Mechanisms and Characterization of Trichoderma longibrachiatum T6 in Suppressing Nematodes (Heterodera avenae) in Wheat.

    PubMed

    Zhang, Shuwu; Gan, Yantai; Ji, Weihong; Xu, Bingliang; Hou, Baohong; Liu, Jia

    2017-01-01

    Heterodera avenae is an important soil-borne pathogen that affects field crops worldwide. Chemical nematicides can be used to control the nematode, but they bring toxicity to the environment and human. Trichoderma longibrachiatum has been shown to have the ability to control H. avenae cysts, but detailed microscopic observations and bioassays are lacking. In this study, we used microscopic observations and bioassays to study the effect of T. longibrachiatum T6 (TL6) on the eggs and second stage juveniles (J2s) of H. avenae, and investigate the role of TL6 in inducing the resistance to H. avenae in wheat seedling at physiological and biochemical levels. Microscopic observations recorded that TL6 parasitized on the H. avenae eggs, germinated, and produced a large number of hyphae on the eggs surface at the initial stage, thereafter, the eggs were completely surrounded by dense mycelia and the contents of eggs were lysed at the late stage. Meanwhile, the conidia suspension of TL6 parasitized on the surface of J2s, produced a large number of hyphae that penetrated the cuticle and caused deformation of the nematodes. TL6 at the concentration of 1.5 × 107 conidia ml-1 had the highest rates of parasitism on eggs and J2s, reflected by the highest hatching-inhibition of eggs and the mortality of J2s. In the greenhouse experiments, wheat seedlings treated with TL6 at 1.5 × 107 conidia ml-1 had reduced H. avenae infection, and increased plant growth significantly compared to the control. The cysts and juveniles in soil were reduced by 89.8 and 92.7%, the juveniles and females in roots were reduced by 88.3 and 91.3%, whereas the activity of chitinase and β-1, 3-glucanase, total flavonoids and lignin contents in wheat roots were increased significantly at different stage after inoculation with the eggs and TL6 conidia in comparison to the control. Maximum activity of chitinase and β-1, 3-glucanase were recorded at the 20th and 15th Days after inoculation with TL6 and

  13. Flow and fracture behavior of aluminum alloy 6082-T6 at different tensile strain rates and triaxialities.

    PubMed

    Chen, Xuanzhen; Peng, Yong; Peng, Shan; Yao, Song; Chen, Chao; Xu, Ping

    2017-01-01

    This study aims to investigate the flow and fracture behavior of aluminum alloy 6082-T6 (AA6082-T6) at different strain rates and triaxialities. Two groups of Charpy impact tests were carried out to further investigate its dynamic impact fracture property. A series of tensile tests and numerical simulations based on finite element analysis (FEA) were performed. Experimental data on smooth specimens under various strain rates ranging from 0.0001~3400 s-1 shows that AA6082-T6 is rather insensitive to strain rates in general. However, clear rate sensitivity was observed in the range of 0.001~1 s-1 while such a characteristic is counteracted by the adiabatic heating of specimens under high strain rates. A Johnson-Cook constitutive model was proposed based on tensile tests at different strain rates. In this study, the average stress triaxiality and equivalent plastic strain at facture obtained from numerical simulations were used for the calibration of J-C fracture model. Both of the J-C constitutive model and fracture model were employed in numerical simulations and the results was compared with experimental results. The calibrated J-C fracture model exhibits higher accuracy than the J-C fracture model obtained by the common method in predicting the fracture behavior of AA6082-T6. Finally, the Scanning Electron Microscope (SEM) of fractured specimens with different initial stress triaxialities were analyzed. The magnified fractographs indicate that high initial stress triaxiality likely results in dimple fracture.

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

    PubMed

    Dunams-Morel, Detiger B; Reichard, Mason V; Torretti, Luigi; Zarlenga, Dante S; Rosenthal, Benjamin M

    2012-04-01

    The genetic diversity within and among parasite populations provides clues to their evolutionary history. Here, we sought to determine whether mitochondrial and microsatellite DNA variation could be used to evaluate the extent of differentiation, gene flow and historical reproductive isolation among the freeze resistant parasites Trichinella nativa and the Trichinella T6 genotype infecting wolverines (Gulo gulo) in Nunavut, Canada. To this end, we genotyped Trichinella isolates derived from the diaphragms of 39 wolverines from this locale to reference strains of T. nativa and the Trichinella T6 genotype. Results showed that among a subset of 13 isolates examined, individuals resembled T. nativa in their mitochondrial DNA, but resembled the Trichinella T6 genotype when assayed at expansion segment V and the internal transcribed spacer of the nuclear rDNA. To adjudicate among these conflicting diagnoses, we further characterized each isolate at several nuclear microsatellite loci and again compared these to data from reference strains. Statistical assignment established that the nuclear genomes of most Nunavut isolates corresponded to those of the Trichinella T6 genotype; however, two isolates corresponded to T. nativa, and one isolate exhibited equal similarity to both reference strains. Taken as a whole, the evidence suggests that these isolates derive from the T. nativa matrilineage, but that their nuclear genomes resemble individuals previously designated as Trichinella T6. Assuming distinct lineages, this argues for cross-hybridization among these genotypes. Although introgression has occurred, recognizable genetic distinctions persist. One possibility is that selection disfavors the survival of hybrid offspring in most instances. Alternatively, the recent disappearance of glacial barriers might have increased contact, and therefore introgression. Broader geographic sampling will be required to determine the extent to which hybridization occurs beyond this

  15. Effect of holding pressure on microstructure and fracture behavior of low-pressure die cast A356-T6 alloy

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoyan; Yun, Ying; Zhang, Huarui; Ma, Zhen; Jia, Lina; Tao, Tongxiang; Zhang, Hu

    2017-12-01

    The effect of different holding pressures on microstructure, tensile properties and fracture behavior of A356-T6 aluminum alloy was investigated. It was observed that the ultimate strength, yield strength and elongation of A356-T6 aluminum alloy increased with the increasing of holding pressure from 85 kPa to 300 kPa. This was attributed to the finer microstructure and the elimination of porosity defects caused by high holding pressure. The fractographs of specimens obtained under lower holding pressure displayed mixed quasi-cleavage and dimple type morphology with flat dimples and large amount of porosities. However, the fractographs of specimens obtained under high holding pressure of 300 kPa clearly exhibited a dimple morphology with small and deep dimples. The differences in the tensile fracture were attributed to the different shape of eutectic Si particle and different amount of porosity defects.

  16. Expression, purification and preliminary crystallographic analysis of the T6SS effector protein Tse3 from Pseudomonas aeruginosa

    PubMed Central

    Lu, Defen; Shang, Guijun; Yu, Qian; Zhang, Heqiao; Zhao, Yanyu; Cang, Huaixing; Gu, Lichuan; Xu, Sujuan; Huang, Yan

    2013-01-01

    Pseudomonas aeruginosa uses the type VI secretion system (T6SS) to inject effector proteins into rival cells in niche competition. Tse3, one of the effectors of T6SS, is delivered into the periplasm of recipient cells. Tse3 functions as a muramidase that degrades the β-1,4-linkage between N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) in peptidoglycan, thus leading to lysis of the recipient cells and providing a competitive advantage to the donor cells. Here, the preliminary crystallographic study of Tse3 is reported. A crystal of Tse3 diffracted to 1.5 Å resolution. It belonged to space group C121, with unit-cell parameters a = 166.99, b = 70.13, c = 41.94 Å, α = 90.00, β = 90.52, γ  = 90.00° and one molecule per asymmetric unit. PMID:23695568

  17. Expression, purification and preliminary crystallographic analysis of the T6SS effector protein Tse3 from Pseudomonas aeruginosa.

    PubMed

    Lu, Defen; Shang, Guijun; Yu, Qian; Zhang, Heqiao; Zhao, Yanyu; Cang, Huaixing; Gu, Lichuan; Xu, Sujuan; Huang, Yan

    2013-05-01

    Pseudomonas aeruginosa uses the type VI secretion system (T6SS) to inject effector proteins into rival cells in niche competition. Tse3, one of the effectors of T6SS, is delivered into the periplasm of recipient cells. Tse3 functions as a muramidase that degrades the β-1,4-linkage between N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) in peptidoglycan, thus leading to lysis of the recipient cells and providing a competitive advantage to the donor cells. Here, the preliminary crystallographic study of Tse3 is reported. A crystal of Tse3 diffracted to 1.5 Å resolution. It belonged to space group C121, with unit-cell parameters a = 166.99, b = 70.13, c = 41.94 Å, α = 90.00, β = 90.52, γ  = 90.00° and one molecule per asymmetric unit.

  18. Exploring the catalytic activity of pristine T6[100] surface for oxygen reduction reaction: A first-principles study

    NASA Astrophysics Data System (ADS)

    Banerjee, Paramita; Chakrabarty, Soubhik; Thapa, Ranjit; Das, G. P.

    2017-10-01

    The electrocatalytic activity of T6[100] surface containing both sp3 (C1) and sp2 (C2) hybridized carbon atoms is explored using first-principles density functional theory based approach. The top layered C1 atom of the surface is found to be more active towards the oxygen reduction reaction (ORR), as compared to that of C2 atom. This is attributed to the presence of dangling σ bond in the corresponding C1 atom, leading to the high electron density near the Ferrmi level. Whereas, the π electron in the top layered C2 atom forms a weak out of plane network. As estimated from free energy profile, the overpotential is much lower when C1 is considered as the active site and the final step i.e desorption of final OH- ion is found to be the potential determining step. We have also reported the effect of Si dopant on the catalytic activity of T6[100] surface and explained the origin of high overpotential value in this case. Thus in this report, we propose a new metal-free catalyst i.e T6[100] surface, having both sp2 (maintains the high metallicity needed to reduce ohmic loss) and sp3 (helps in capturing the upcoming molecules) hybridized carbon atoms, as a potential candidate for ORR.

  19. UV spectroscopic identification and thermodynamic analysis of protonated third strand deoxycytidine residues at neutrality in the triplex d(C(+)-T)6:[d(A-G)6.d(C-T)6]; evidence for a proton switch.

    PubMed

    Lavelle, L; Fresco, J R

    1995-07-25

    Near-UV difference spectral analysis of the triplex formed from d(C-T)6 and d(A-G)6.d(C-T)6 in neutral and acidic solution shows that the third strand dC residues are protonated at pH 7.0, far above their intrinsic pKa. Additional support for ion-dipole interactions between the third strand dC residues and the G.C target base pairs comes from reduced positive dependence of triplet stability on ionic strength below 0.9 M Na+, inverse dependence above 0.9 M Na+ and strong positive dependence on hydrogen ion concentration. Molecular modeling (AMBER) of C:G.C and C+:G.C base triplets with the third strand base bound in the Hoogsteen geometry shows that only the C+:G.C triplet is energetically feasible. van't Hoff analysis of the melting of the triplex and target duplex shows that between pH 5.0 and 8.5 in 0.15 M NaCl/0.005 M MgCl2 the enthalpy of melting (delta H degree obs) varies from 5.7 to 6.6 kcal.mol-1 for the duplex in a duplex mixture and from 7.3 to 9.7 kcal.mol-1 for third strand dissociation in the triplex mixture. We have extended the condensation-screening theory of Manning to pH-dependent third strand binding. In this development we explicitly include the H+ contribution to the electrostatic free energy and obtain [formula: see text]. The number of protons released in the dissociation of the third strand from the target duplex at pH 7.0, delta n2, is thereby calculated to be 5.5, in good agreement with approximately six third strand dc residues per mole of triplex. This work shows that when third strand binding requires protonated residues that would otherwise be neutral, triplex formation and dissociation are mediated by proton uptake and release, i.e., a proton switch. As a by-product of this study, we have found that at low pH the Watson-Crick duplex d(A-G)6.d(C-T)6 undergoes a transition to a parallel Hoogsteen duplex d(A-G)6.d(C(+)-T)6.

  20. 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

  1. Mechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Astarita, A.; Squillace, A.; Nele, L.

    2016-01-01

    Butt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds.

  2. Effects of die quench forming on sheet thinning and 3-point bend testing of AA7075-T6

    NASA Astrophysics Data System (ADS)

    Kim, Samuel; Omer, Kaab; Rahmaan, Taamjeed; Butcher, Clifford; Worswick, Michael

    2017-10-01

    Lab-scaled AA7075 aluminum side impact beams were manufactured using the die quenching technique in which the sheet was solutionized and then quenched in-die during forming to a super saturated solid state. Sheet thinning measurements were taken at various locations throughout the length of the part and the effect of lubricant on surface scoring and material pick-up on the die was evaluated. The as-formed beams were subjected to a T6 aging treatment and then tested in three-point bending. Simulations were performed of the forming and mechanical testing experiments using the LS-DYNA finite element code. The thinning and mechanical response was predicted well.

  3. Corrosion behaviour of friction-bit-joined and weld-bonded AA7075-T6/galvannealed DP980

    SciTech Connect

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

    2016-12-22

    Joining of aluminium alloys 7075-T6 and galvannealed dual phase 980 steel was achieved by friction bit joining (FBJ) and weld-bonding (FBJ + adhesive) processes. Accelerated laboratory-scale corrosion tests were performed on both FBJ only and weld-bonded specimens to study joint strength under a corrosive environment. Static lap shear tests showed that both FBJ only and weld-bonded cases generally retained more than 80% of the joint strength of non-corroded specimens at the end of corrosion testing. The presence of Zn/Fe coating on the steel substrate resulted in improved corrosion resistance for FBJ specimens, compared to joints produced with bare steel. Finally, an optical microscopy was used for cross-sectional analysis of corroded specimens. Some corrosion on the joining bit was observed near the bit head. However, the joining bit was still intact on the steel substrate, indicating that the primary bond was sound.

  4. 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.

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

    SciTech Connect

    Patel, Dhruv, E-mail: dhruv7654@gmail.com; Davda, Chintan; Keshvani, M. J.

    2016-05-06

    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 treatmentmore » and soaking time has been discussed in detail.« less

  6. 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.

  7. 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

    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-6more » (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.« less

  8. Effect of the Zener-Hollomon parameter on the formability of AA6082-T6 formed at elevated temperature

    NASA Astrophysics Data System (ADS)

    Novella, Michele F.; Ghiotti, Andrea; Bruschi, Stefania

    2016-10-01

    Material formability is one of the main research topics in metal forming, but it is usually regarded as a secondary concern in processes carried out at high temperature. Though usually entailing higher material ductility, the high temperature used in hot forging can lead to the phenomenon of hot shortness, with fall of material formability due to the microstructural changes during the deformation. Hot metal formability modelling can imply three main issues: (i) the lack of models expressly developed for high temperatures, (ii) the exponential increase of the experimental effort which is needed for the model calibration, since different thermo-mechanical conditions need to be tested, according to the process window parameters, and consequently (iii) the more complex model calibration, especially if inverse analysis techniques are used. In this work the formability of the AA6082-T6 aluminum alloy is investigated by means of tensile tests carried out at different temperatures and strain rates. The hot shortness onset is identified as well as the negative strain rate influence on the material maximum strain at fracture. A linear dependency of the material formability on the Zener-Hollomon parameter is established for temperatures below the hot shortness point, allowing a significant simplification of the experiments needed for the calibration. A new formability model is proposed to overcome the limits of the linear correlation thanks to the introduction of a critical value of the Zener-Hollomon parameter. The Oyane-Sato damage criterion is then extended to hot conditions using the afore mentioned Zener-Hollomon dependency. Finally, the approach is validated on the reference industrial case: the cross wedge rolling of AA6082-T6 round bars carried out at elevated temperature showing axial cracking due to Mannesmann effect.

  9. Maximal physiological responses during arm cranking and treadmill wheelchair propulsion in T4-T6 paraplegic men.

    PubMed

    Gass, E M; Harvey, L A; Gass, G C

    1995-05-01

    The aim of the study was to compare the exercise responses during maximum wheelchair propulsion on a motor driven treadmill (TM) and maximum arm cranking (AC) in a homogenous group of nine paraplegic men with clinically complete spinal cord lesions between T4 and T6. The test order for each ergometer was random and time between the two ergometer tests was 3-7 days. All experiments were conducted in an air conditioned environment (23 degrees C DB, 18 degrees C WB). The highest VO2 recorded during the final minute of arm cranking (1.65 +/- 0.14 l min-1) and wheelchair propulsion on the treadmill (1.72 +/- 0.10 l min-1) was not significantly different. There were no significant differences in heart rate during the final minute of arm cranking (177 +/- 3 b min-1), and wheelchair propulsion on a motor driven treadmill (177 +/- 4 b min-1), nor were there any significant differences in minute ventilation (STPD) between AC (52 +/- 6.6 l min-1) and TM (56.1 +/- 4.8 l min-1). The VCO2 l min-1 for AC (2.00 +/- 0.20 l min-1) and TM (2.00 +/- 0.12 l min-1) was also not significantly different. The present study found that, unlike previous studies, no significant differences in VO2 (l min-1, ml kg-1 min-1) VE (l min-1), VCO2 (l min-1) or heart rate (b min-1) were found between the two modes of ergometry during the last minute of incremental exercise to exhaustion in a homogenous group of T4-T6 paraplegic men.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Application of Plant-Growth-Promoting Fungi Trichoderma longibrachiatum T6 Enhances Tolerance of Wheat to Salt Stress through Improvement of Antioxidative Defense System and Gene Expression.

    PubMed

    Zhang, Shuwu; Gan, Yantai; Xu, Bingliang

    2016-01-01

    Soil salinity is a serious problem worldwide that reduces agricultural productivity. Trichoderma longibrachiatum T6 (T6) has been shown to promote wheat growth and induce plant resistance to parasitic nematodes, but whether the plant-growth-promoting fungi T6 can enhance plant tolerance to salt stress is unknown. Here, we determined the effect of plant-growth-promoting fungi T6 on wheat seedlings' growth and development under salt stress, and investigated the role of T6 in inducing the resistance to NaCl stress at physiological, biochemical, and molecular levels. Wheat seedlings were inoculated with the strain of T6 and then compared with non-inoculated controls. Shoot height, root length, and shoot and root weights were measured on 15 days old wheat seedlings grown either under 150 mM NaCl or in a controlled setting without any NaCl. A number of colonies were re-isolated from the roots of wheat seedlings under salt stress. The relative water content in the leaves and roots, chlorophyll content, and root activity were significantly increased, and the accumulation of proline content in leaves was markedly accelerated with the plant growth parameters, but the content of leaf malondialdehyde under saline condition was significantly decreased. The antioxidant enzymes-superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in wheat seedlings were increased by 29, 39, and 19%, respectively, with the application of the strain of T6 under salt stress; the relative expression of SOD, POD, and CAT genes in these wheat seedlings were significantly up-regulated. Our results indicated that the strain of T6 ameliorated the adverse effects significantly, protecting the seedlings from salt stress during their growth period. The possible mechanisms by which T6 suppresses the negative effect of NaCl stress on wheat seedling growth may be due to the improvement of the antioxidative defense system and gene expression in the stressed wheat plants.

  11. Plastic Stress-strain Relations for 75S-T6 Aluminum Alloy Subjected to Biaxial Tensile Stresses

    NASA Technical Reports Server (NTRS)

    Marin, Joseph; Ulrich, B H; Hughes, W P

    1951-01-01

    In this investigation, the material tested was a 75S-T6 aluminum alloy and the stresses were essentially biaxial and tensile. The biaxial tensile stresses were produced in a specially designed testing machine by subjecting a thin-walled tubular specimen to axial tension and internal pressure. Plastic stress-strain relations for various biaxial stress conditions were obtained using a clip-type SR-4 strain gage. Three types of tests were made: Constant-stress-ratio tests, variable-stress-ratio tests, and special tests. The constant-stress-ratio test results gave control data and showed the influence of biaxial stresses on the yield, fracture, and ultimate strength of the material. By means of the variable-stress-ratio tests, it is possible to determine whether there is any significant difference between the flow and deformation type of theory. Finally, special tests were conducted to check specific assumptions made in the theories of plastic flow. The constant-stress-ratio tests show that the deformation theory based on the octahedral, effective; or significant stress-strain relations is in approximate agreement with the test results. The variable-stress-ratio tests show that both the deformation and flow theory are in equally good agreement with the test results.

  12. Adsorption of BTSE and γ-GPS organosilanes on different microstructural regions of 7075-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Kim, J.; Wong, P. C.; Wong, K. C.; Sodhi, R. N. S.; Mitchell, K. A. R.

    2007-01-01

    The adsorption of bis-1,2-(triethoxysilyl)ethane (BTSE) and γ-glycidoxypropyltrimethoxysilane (γ-GPS) on mirror-polished 7075-T6 aluminum alloy was studied with an emphasis on the different microstructural regions of the alloy surface, specifically the alloy matrix and the two main types of second-phase particles, as well as how the adsorption was affected by a heating pre-treatment and by changes in the pH of the γ-GPS solution. Surface characterizations were undertaken with scanning Auger microscopy (SAM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and time-of-flight secondary-ion mass spectrometry (TOF-SIMS). BTSE at its natural pH (4.3) adsorbed at all micro-regions of the air-oxidized surface, while γ-GPS at its natural pH (5.7) was largely ineffective. Adsorption of γ-GPS on all micro-regions was possible after adjusting the solution pH to a lower value (3.2), or by using the solution of natural pH after pre-treating the sample by heating at 200 °C for 15 min. TOF-SIMS measurements indicated that direct metal-O-Si covalent bonding occurred at each silane interface formed to the different micro-regions of the alloy surface, with Al-O-Si bonding being predominant in each case.

  13. 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.

  14. VARIABLE AND POLARIZED RADIO EMISSION FROM THE T6 BROWN DWARF WISEP J112254.73+255021.5

    SciTech Connect

    Williams, P. K. G.; Berger, E.; Gizis, J. E., E-mail: pwilliams@cfa.harvard.edu

    2017-01-10

    Route and Wolszczan recently detected five radio bursts from the T6 dwarf WISEP J112254.73+255021.5 and used the timing of these events to propose that this object rotates with an ultra-short period of ∼17.3 minutes. We conducted follow-up observations with the Very Large Array and Gemini-North but found no evidence for this periodicity. We do, however, observe variable, highly circularly polarized radio emission. Assuming that the radio emission of this T dwarf is periodically variable on ∼hour timescales, like other radio-active ultracool dwarfs, we infer a likely period of 116 minutes. However, our observation lasted only 162 minutes and so more data are needed to test thismore » hypothesis. The handedness of the circular polarization switches twice and there is no evidence for any unpolarized emission component, the first time such a phenomenology has been observed in radio studies of very low-mass stars and brown dwarfs. We suggest that the object’s magnetic dipole axis may be highly misaligned relative to its rotation axis.« less

  15. Evaluation of Fatigue Behavior and Surface Characteristics of Aluminum Alloy 2024 T6 After Electric Discharge Machining

    NASA Astrophysics Data System (ADS)

    Mehmood, Shahid; Shah, Masood; Pasha, Riffat Asim; Sultan, Amir

    2017-10-01

    The effect of electric discharge machining (EDM) on surface quality and consequently on the fatigue performance of Al 2024 T6 is investigated. Five levels of discharge current are analyzed, while all other electrical and nonelectrical parameters are kept constant. At each discharge current level, dog-bone specimens are machined by generating a peripheral notch at the center. The fatigue tests are performed on four-point rotating bending machine at room temperature. For comparison purposes, fatigue tests are also performed on the conventionally machined specimens. Linearized SN curves for 95% failure probability and with four different confidence levels (75, 90, 95 and 99%) are plotted for each discharge current level as well as for conventionally machined specimens. These plots show that the electric discharge machined (EDMed) specimens give inferior fatigue behavior as compared to conventionally machined specimen. Moreover, discharge current inversely affects the fatigue life, and this influence is highly pronounced at lower stresses. The EDMed surfaces are characterized by surface properties that could be responsible for change in fatigue life such as surface morphology, surface roughness, white layer thickness, microhardness and residual stresses. It is found that all these surface properties are affected by changing discharge current level. However, change in fatigue life by discharge current could not be associated independently to any single surface property.

  16. Dislocation density evolution of AA 7020-T6 investigated by in-situ synchrotron diffraction under tensile load

    SciTech Connect

    Zhong, Z.Y.; Brokmeier, H.-G.; Gan, W.M.; Maawad, E.; Schwebke, B.; Schell, N.

    2015-10-15

    The dislocation density evolution along the loading axis of a textured AA 7020-T6 aluminum alloy during uniaxial tension was investigated by in-situ synchrotron diffraction. The highly parallel synchrotron beam at the High Energy Materials Science beamline P07 in PETRA III, DESY, offers excellent conditions to separate different influences for line broadening from which micro-strains are obtained using the modified Williamson–Hall method which is also for defect density investigations. During tensile loading the dislocation density evolution was documented from the as-received material (initial micro-strain state) to the relaxation of the strains during elastic deformation. After yield, the increasing rate of dislocation density growth was relatively fast till half-way between yield and UTS. After that, the rate started to decrease and the dislocation density fluctuated as the elongation increased due to the generation and annihilation of dislocations. When dislocation generation is dominant, the correlation between the flow stress and dislocation density satisfies the Taylor equation. Besides, a method to correct the thickness effect on peak broadening is developed in the present study. - Highlights: • In-situ synchrotron diffraction was applied to characterize peak broadening. • Dislocation evolution along the loading axis during uniaxial tension was investigated. • A method to correct the sample thickness effect on peak broadening was developed. • Dislocation density and flow stress satisfy the Taylor equation at a certain range. • The texture before load and after sample fracture was analyzed.

  17. Corrosion behaviour of friction-bit-joined and weld-bonded AA7075-T6/galvannealed DP980

    SciTech Connect

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu

    2016-12-22

    Joining of aluminium alloys 7075-T6 and galvannealed dual phase 980 steel was achieved by friction bit joining (FBJ) and weld-bonding (FBJ + adhesive) processes. Accelerated laboratory-scale corrosion tests were performed on both FBJ only and weld-bonded specimens to study joint strength under a corrosive environment. Static lap shear tests showed that both FBJ only and weld-bonded cases generally retained more than 80% of the joint strength of non-corroded specimens at the end of corrosion testing. The presence of Zn/Fe coating on the steel substrate resulted in improved corrosion resistance for FBJ specimens, compared to joints produced with bare steel. Finally,more » an optical microscopy was used for cross-sectional analysis of corroded specimens. Some corrosion on the joining bit was observed near the bit head. However, the joining bit was still intact on the steel substrate, indicating that the primary bond was sound.« less

  18. 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.

  19. 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.

  20. t(6;11) Renal Cell Carcinoma (RCC) Expanded Immunohistochemical Profile Emphasizing Novel RCC Markers and Report of 10 New Genetically Confirmed Cases

    PubMed Central

    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

    2015-01-01

    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 Uro-logical Pathology Vancouver Classification of Renal Neoplasia. Although these RCCs are known to label for melanocytic markers HMB45 and Melan A and the cysteine protease cath-epsin 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

  1. Molecular identification of natural hybrids between Trichinella nativa and Trichinella T6 provides evidence of gene flow and ongoing genetic divergence.

    PubMed

    La Rosa, G; Marucci, G; Zarlenga, D S; Casulli, A; Zarnke, R L; Pozio, E

    2003-02-01

    To date, there are no data available on the population genetics of Trichinella due to the lack of genetic markers and the difficulty of working with such small parasites. In the Arctic region of North America and along the Rocky Mountains, there exist two genotypes of Trichinella, Trichinella nativa and Trichinella T6, respectively, which are well differentiated by biochemical and molecular characters. However, both are resistant to freezing, show other common biological characters (e.g. low or no infectivity to rodents and swine) and produce fertile F1 offspring upon interbreeding. To data, these two genotypes have been considered allopatric. In this study, we detected both genotypes in wolves of the same wolf packs in Alaska, suggesting sympatry. A single GTT trinucleotide present in the ITS-2 sequence of T. nativa but not in Trichinella T6 was used as a genetic marker to study gene flow for this character in both a murine infection model and in larvae from naturally-infected Alaskan wolves. Only F1 larvae originating from a cross between T. nativa male and Trichinella T6 female were able to produce F2 offspring. Larvae (F1) originating from a cross between Trichinella T6 male and T. nativa female were not reproductively viable. As expected, all F1 larvae showed a heterozygote pattern for the GTT character upon heteroduplex analysis; however, within the F2 population, the number of observed heterozygotes (n=52) was substantially higher than expected (n=39.08), as supported by the F(is) index, and was not in the Hardy-Weinberg equilibrium. Larvae from two of the 16 Trichinella positive Alaskan wolves, showed the Trichinella T6 pattern or the T. nativa/Trichinella T6 hybrid pattern. Our data demonstrate that T. nativa and Trichinella T6 live in sympatry at least in Alaskan wolves, where T. nativa occurs more frequently (69%) than Trichinella T6 (31%). One explanation for this phenomenon is that glacial periods may have caused a geographical relocation, colonisation

  2. 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

  3. Dioscin Inhibits HSC-T6 Cell Migration via Adjusting SDC-4 Expression: Insights from iTRAQ-Based Quantitative Proteomics.

    PubMed

    Yin, Lianhong; Qi, Yan; Xu, Youwei; Xu, Lina; Han, Xu; Tao, Xufeng; Song, Shasha; Peng, Jinyong

    2017-01-01

    Hepatic stellate cells (HSCs) migration, an important bioprocess, contributes to the development of liver fibrosis. Our previous studies have found the potent activity of dioscin against liver fibrosis by inhibiting HSCs proliferation, triggering the senescence and inducing apoptosis of activated HSCs, but the molecular mechanisms associated with cell migration were not clarified. In this work, iTRAQ (isobaric tags for relative and absolution quantitation)-based quantitative proteomics study was carried out, and a total of 1566 differentially expressed proteins with fold change ≥2.0 and p < 0.05 were identified in HSC-T6 cells treated by dioscin (5.0 μg/mL). Based on Gene Ontology classification, String and KEGG pathway assays, the effects of dioscin to inhibit cell migration via regulating SDC-4 were carried out. The results of wound-healing, cell migration and western blotting assays indicated that dioscin significantly inhibit HSC-T6 cell migration through SDC-4-dependent signal pathway by affecting the expression levels of Fn, PKCα, Src, FAK, and ERK1/2. Specific SDC-4 knockdown by shRNA also blocked HSC-T6 cell migration, and dioscin slightly enhanced the inhibiting effect. Taken together, the present work showed that SDC-4 played a crucial role on HSC-T6 cell adhesion and migration of dioscin against liver fibrosis, which may be one potent therapeutic target for fibrotic diseases.

  4. Dioscin Inhibits HSC-T6 Cell Migration via Adjusting SDC-4 Expression: Insights from iTRAQ-Based Quantitative Proteomics

    PubMed Central

    Yin, Lianhong; Qi, Yan; Xu, Youwei; Xu, Lina; Han, Xu; Tao, Xufeng; Song, Shasha; Peng, Jinyong

    2017-01-01

    Hepatic stellate cells (HSCs) migration, an important bioprocess, contributes to the development of liver fibrosis. Our previous studies have found the potent activity of dioscin against liver fibrosis by inhibiting HSCs proliferation, triggering the senescence and inducing apoptosis of activated HSCs, but the molecular mechanisms associated with cell migration were not clarified. In this work, iTRAQ (isobaric tags for relative and absolution quantitation)-based quantitative proteomics study was carried out, and a total of 1566 differentially expressed proteins with fold change ≥2.0 and p < 0.05 were identified in HSC-T6 cells treated by dioscin (5.0 μg/mL). Based on Gene Ontology classification, String and KEGG pathway assays, the effects of dioscin to inhibit cell migration via regulating SDC-4 were carried out. The results of wound-healing, cell migration and western blotting assays indicated that dioscin significantly inhibit HSC-T6 cell migration through SDC-4-dependent signal pathway by affecting the expression levels of Fn, PKCα, Src, FAK, and ERK1/2. Specific SDC-4 knockdown by shRNA also blocked HSC-T6 cell migration, and dioscin slightly enhanced the inhibiting effect. Taken together, the present work showed that SDC-4 played a crucial role on HSC-T6 cell adhesion and migration of dioscin against liver fibrosis, which may be one potent therapeutic target for fibrotic diseases. PMID:29033837

  5. Modulation of the Proteostasis Machinery to Overcome Stress Caused by Diminished Levels of t6A-Modified tRNAs in Drosophila

    PubMed Central

    Rojas-Benítez, Diego; Eggers, Cristián; Glavic, Alvaro

    2017-01-01

    Transfer RNAs (tRNAs) harbor a subset of post-transcriptional modifications required for structural stability or decoding function. N6-threonylcarbamoyladenosine (t6A) is a universally conserved modification found at position 37 in tRNA that pair A-starting codons (ANN) and is required for proper translation initiation and to prevent frame shift during elongation. In its absence, the synthesis of aberrant proteins is likely, evidenced by the formation of protein aggregates. In this work, our aim was to study the relationship between t6A-modified tRNAs and protein synthesis homeostasis machinery using Drosophila melanogaster. We used the Gal4/UAS system to knockdown genes required for t6A synthesis in a tissue and time specific manner and in vivo reporters of unfolded protein response (UPR) activation. Our results suggest that t6A-modified tRNAs, synthetized by the threonyl-carbamoyl transferase complex (TCTC), are required for organismal growth and imaginal cell survival, and is most likely to support proper protein synthesis. PMID:28272317

  6. Production of antimicrobial substances by Bacillus subtilis LFE-1, B. firmus HO-1 and B. licheniformis T6-5 isolated from an oil reservoir in Brazil.

    PubMed

    Korenblum, E; der Weid, I; Santos, A L S; Rosado, A S; Sebastián, G V; Coutinho, C M L M; Magalhães, F C M; Paiva, M M; Seldin, L

    2005-01-01

    Forty Bacillus strains isolated from a Brazilian oil reservoir were tested against each other to select strains producing antimicrobial substances (AMS). Three strains, Bacillus subtilis (LFE-1), Bacillus firmus (H2O-1) and Bacillus licheniformis (T6-5), were selected due to their ability to inhibit more than 65% of the Bacillus strains tested. These three strains were also investigated for their capability to inhibit sulphate-reducing bacteria (SRB). Furthermore, physiological and biochemical characteristics of the antimicrobial compounds produced by the selected strains were determined. Among the forty strains tested, 36 (90%) strains were able to inhibit at least one Bacillus strain used as indicator in plate assays and three of them (LFE-1, T6-5 and H2O-1) were able to inhibit 65, 70 and 97.5% of the 40 strains studied here respectively. Clear zones of inhibition were observed when H2O-1 was tested against SRB-containing consortium T6-lab and Desulfovibrio alaskensis strain NCIMB 13491, while strain T6-5 was able to inhibit only the D. alaskensis strain. The three substances showed to be insensitive to different enzymes and chemicals, were heat stable and the substances produced by strains T6-5 and H2O-1 were active over a wide pH range. Three different AMS produced by Bacillus strains from an oil reservoir, two of them with activity against SRB, are presented here. The preliminary characterization of these AMS points to their potential use as biocides in the petroleum industry for controlling problems associated with SRB.

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

    PubMed

    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

    2014-05-01

    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.

  8. 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.

  9. Preferences of AAA/AAG codon recognition by modified nucleosides, τm5s2U34 and t6A37 present in tRNALys.

    PubMed

    Sonawane, Kailas D; Kamble, Asmita S; Fandilolu, Prayagraj M

    2017-12-27

    Deficiency of 5-taurinomethyl-2-thiouridine, τm5s2U at the 34th 'wobble' position in tRNALys causes MERRF (Myoclonic Epilepsy with Ragged Red Fibers), a neuromuscular disease. This modified nucleoside of mt tRNALys, recognizes AAA/AAG codons during protein biosynthesis process. Its preference to identify cognate codons has not been studied at the atomic level. Hence, multiple MD simulations of various molecular models of anticodon stem loop (ASL) of mt tRNALys in presence and absence of τm5s2U34 and N6-threonylcarbamoyl adenosine (t6A37) along with AAA and AAG codons have been accomplished. Additional four MD simulations of multiple ASL mt tRNALys models in the context of ribosomal A-site residues have also been performed to investigate the role of A-site in recognition of AAA/AAG codons. MD simulation results show that, ASL models in presence of τm5s2U34 and t6A37 with codons AAA/AAG are more stable than the ASL lacking these modified bases. MD trajectories suggest that τm5s2U recognizes the codons initially by 'wobble' hydrogen bonding interactions, and then tRNALys might leave the explicit codon by a novel 'single' hydrogen bonding interaction in order to run the protein biosynthesis process smoothly. We propose this model as the 'Foot-Step Model' for codon recognition, in which the single hydrogen bond plays a crucial role. MD simulation results suggest that, tRNALys with τm5s2U and t6A recognizes AAA codon more preferably than AAG. Thus, these results reveal the consequences of τm5s2U and t6A in recognition of AAA/AAG codons in mitochondrial disease, MERRF.

  10. Surface Characterizations of Fretting Fatigue Damage in Aluminum Alloy 7075-T6 Clamped Joints: The Beneficial Role of Ni–P Coatings

    PubMed Central

    Oskouei, Reza H.; Barati, Mohammad Reza; Ibrahim, Raafat N.

    2016-01-01

    This paper aims to characterize the surface damage as a consequence of fretting fatigue in aluminum alloy 7075-T6 plates in double-lap bolted joints through XRD, surface profilometry, and SEM analyses. The main focus was on the surface roughness and chemical phase composition of the damaged zone along with the identification of fretting fatigue crack initiations over the surface of the material. The surface roughness of the fretted zone was found to increase when the joint was clamped with a higher tightening torque and tested under the same cyclic loading. Additionally, MgZn2 (η/ή) precipitates and ZnO phase were found to form onto the surface of uncoated aluminum plate in the fretted and worn zones. The formation of the ZnO phase was understood to be a result of frictional heat induced between the surface of contacting uncoated Al 7075-T6 plates during cyclic loading and exposure to the air. The beneficial role of electroless nickel-phosphorous (Ni–P) coatings in minimizing the fretting damage and thus improving the fretting fatigue life of the aluminum plates was also studied. The results showed that the surface roughness decreased by approximately 40% after applying Ni–P coatings to the Al 7075-T6 plates. PMID:28773267

  11. 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.

  12. Genomic analysis of the biocontrol strain Pseudomonas fluorescens Pf29Arp with evidence of T3SS and T6SS gene expression on plant roots.

    PubMed

    Marchi, Muriel; Boutin, Morgane; Gazengel, Kévin; Rispe, Claude; Gauthier, Jean-Pierre; Guillerm-Erckelboudt, Anne-Yvonne; Lebreton, Lionel; Barret, Matthieu; Daval, Stéphanie; Sarniguet, Alain

    2013-06-01

    Several bacterial strains of the Pseudomonas genus provide plant growth stimulation, plant protection against pests or bioremediation. Among these bacteria, P. fluorescens Pf29Arp reduces the severity of take-all, a disease caused by the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) on wheat roots. In this study, we obtained a draft genome of Pf29Arp and subsequent comparative genomic analyses have revealed that this bacterial strain is closely related to strains of the 'P. brassicacearum-like' subgroup including P. brassicacearum ssp. brassicacearum NFM421 and P. fluorescens F113. Despite an overall chromosomal organization similar to these strains, a number of features including antibiotic synthesis gene clusters from secondary metabolism are not found in the Pf29Arp genome. But Pf29Arp possesses different protein secretion systems including type III (T3SS) and type VI (T6SS) secretion systems. Pf29Arp is the first Pseudomonas sp. strain described with four T6SS clusters (cluster I, II, III and IV). In addition, some protein-coding genes involved in the assembly of these secretion systems are basally expressed during Pf29Arp colonization of healthy wheat roots and display different expression patterns on necrotized roots caused by Ggt. These data suggest a role of T3SS and T6SS in the Pf29Arp adaptation to different root environments. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology.

  13. 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.

  14. The structural basis of the Tle4-Tli4 complex reveals the self-protection mechanism of H2-T6SS in Pseudomonas aeruginosa.

    PubMed

    Lu, Defen; Zheng, Youshi; Liao, Naishun; Wei, Ling; Xu, Bo; Liu, Xiaolong; Liu, Jingfeng

    2014-12-01

    The type VI secretion system (T6SS) has recently been demonstrated to mediate interbacterial competition and to discriminate between self and nonself. T6SS(+) bacteria employ toxic effectors to inhibit rival cells and concurrently use effector cognate immunity proteins to protect their sibling cells. The effector and immunity pairs (E-I pairs) endow the bacteria with a great advantage in niche competition. Tle4-Tli4 (PA1510-PA1509) is a newly identified E-I pair that is controlled by H2-T6SS in Pseudomonas aeruginosa. Tle4 exhibits phospholipase activity, which destroys the cell membrane of rival cells, and the periplasm-located Tli4 in donor cells eliminates this toxic effect of Tle4. In this paper, the structure of the Tle4-Tli4 complex is reported at 1.75 Å resolution. Tle4 consists of two domains: a conserved α/β-hydrolase domain and an unusual cap domain in which two lid regions (lid1 and lid2) display a closed conformation that buries the catalytic triad in a deep funnel. Tli4 also displays a two-domain structure, in which a large lobe and a small lobe form a crab claw-like conformation. Tli4 uses this crab claw to grasp the cap domain of Tle4, especially the lid2 region, which prevents the interfacial activation of Tle4 and thus causes enzymatic dysfunction of Tle4 in sister cells.

  15. Tn-Seq Analysis of Vibrio cholerae Intestinal Colonization Reveals a Role for T6SS-Mediated Antibacterial Activity in the Host

    PubMed Central

    Fu, Yang; Waldor, Matthew K.; Mekalanos, John J.

    2014-01-01

    SUMMARY Analysis of genes required for host infection will provide clues to the drivers of evolutionary fitness of pathogens like Vibrio cholerae, a mounting threat to global heath. We used transposon insertion site sequencing (Tn-seq) to comprehensively assess the contribution of nearly all V. cholerae genes toward growth in the infant rabbit intestine. Four hundred genes were identified as critical to V. cholerae in vivo fitness. These included most known colonization factors and several new genes affecting the bacterium's metabolic properties, resistance to bile, and ability to synthesize cyclic AMP-GMP. Notably, a mutant carrying an insertion in tsiV3, encoding immunity to a bacteriocidal type VI secretion system (T6SS) effector VgrG3, exhibited a colonization defect. The reduced in vivo fitness of tsiV3 mutants depends on their cocolonization with bacterial cells carrying an intact T6SS locus and VgrG3 gene, suggesting that the V. cholerae T6SS is functional and mediates antagonistic interbacterial interactions during infection. PMID:24331463

  16. Investigation of the Discharge Characteristics of the T6 Hollow Cathode Operating on Several Inert Gases and a Kr/Xe Mixture

    NASA Astrophysics Data System (ADS)

    Ahmed Rudwan, M.; Gabriel, S. B.

    2002-01-01

    Investigation of the discharge characteristics of the T6 hollow cathode operating on several inert Xenon is currently the propellant of choice for gridded ion thrusters. But in order to make deep space missions feasible, an increase in the Specific Impulse (SI) that these thrusters can achieve is necessary. One method of achieving this is to use a propellant with a lower atomic mass (e.g. argon), as the propellant exhaust velocity is inversely proportional to the square root of the propellant mass. However, the feasibility of operating the hollow cathode using these alternative propellants has to be demonstrated. Moreover, interest in decreasing the propellant cost in missions and ground testing (especially life tests) have led to the comprehensive discharge characterisation of several gases that will be presented in this paper. A Kr/Xe mixture in the naturally occurring ratio, for example, could offer a 15 times cost saving when compared to pure xenon and 2-3 times cost saving when compared to pure krypton. The T6 hollow cathode discharge behaviour as well as its initiation characteristics have been studied. The tests were carried out in diode configuration using a T6 hollow cathode with an enclosed keeper design employing xenon, krypton, argon and a Kr/Xe mix. The discharge initiation tests were undertaken with a view to investigate some of the factors thought to influence the starting potential such as mass flow rate and tip temperature. It was found that, for mass flow rates ranging from 0.2-1.1 mg/s and cathode tip temperatures ranging from 900-1300oC, the breakdown potential was less than 50V for argon, less than 25V for krypton, less than 21V for xenon and less than 35V for the Kr/Xe mix. The discharge initiation results were then compared to those obtained by Fearn et al. with a T5 cathode operating on mercury and with a T6 cathode utilising an open keeper design using xenon propellant. The xenon breakdown potentials were found to be lower than those

  17. Effect of Quenching Medium on Mechanical Properties of Alloy Al7049-T6 and Lowering of its After-Machining Warpage

    NASA Astrophysics Data System (ADS)

    Sani, Saeed Aliakbari; Feizabadi, Javad; Pourgharibshahi, Mohammad; Hashemi, Seyed Hamidreza

    2017-07-01

    Aluminum alloy Al 7049 is studied in state T6. Heat treatment of the specimens is performed in different quenching media (cold water, boiling water, aqueous polymer solutions). The mechanical properties and the Brinell hardness of the alloy are determined after different modes of heat treatment. Comparative analysis is used to find the maximum residual stresses responsible for warpage of the alloy after machining. The relation between the warpage and the dimensionless Biot number is obtained. Quenching modes removing the warpage in billets of Al7049 are determined.

  18. 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.

  19. Crack Initiation and Growth from Pre-corroded Pits in Aluminum 7075-T6 Under Laboratory Air and Salt Water Environments

    NASA Astrophysics Data System (ADS)

    Joshi, G.; Mall, S.

    2017-05-01

    Small crack growth behavior, including the pit-to-crack transition, of pre-corroded aluminum alloy 7075-T6 was investigated under ambient air and saltwater environments. Through pit and corner crack pits were created prior to constant stress amplitude fatigue testing. The small crack growth life (SCGL) and crack initiation life (CIL) under salt water condition were about 5-8 times less when compared to those under ambient air. The ratio of SCGL to CIL was significantly smaller with large uncertainty (variation) under salt water environment. The small crack growth rates under salt water were 2-12 times larger than corresponding rates under laboratory air at identical stress amplitude and crack length. The crack lengths required to attain Paris region growth rates (Paris region threshold crack lengths) were about 1-3 mm for stress amplitudes less than 45 MPa. Sub-millimeter cracks attained 10-4 mm/cycle fatigue crack growth rates (FCGR) for stress amplitudes greater than 45 MPa. The crack growth rates of 0.25-mm-long cracks were about 2 times higher for salt water environment when compared to identical stress conditions in ambient air. Empirical crack growth rate versus stress intensity factor range equations similar to Paris law were developed for small crack growth and crack initiation under ambient air and salt water condition, for fatigue crack prognostics applications. For the design applications, a modified Kitagawa-Takahashi (K-T) diagram for corrosion-pitted aluminum 7075-T6 is presented.

  20. Translocational renal cell carcinoma (t(6;11)(p21;q12) with transcription factor EB (TFEB) amplification and an integrated precision approach: a case report.

    PubMed

    Lilleby, Wolfgang; Vlatkovic, Ljiljana; Meza-Zepeda, Leonardo A; Revheim, Mona-Elisabeth; Hovig, Eivind

    2015-12-09

    Renal cell carcinoma with the distinct type of t(6;11)(p21;q12) translocation (transcription factor EB) is a rare neoplasm. In the present case study, we show for the first time an autophagy signature in a patient with transcription factor EB renal cell carcinoma. We attempted to characterize the mutational and expressional features of a t(6;11)(p21;q12) renal cell carcinoma, in an effort to address the potential for molecular guidance of personalized medical decision for a case in this renal cell carcinoma category. We report the case of a 42-year-old white man who had a late relapse of his renal cell carcinoma. The first diagnosis of clear cell renal carcinoma was derived from a histological examination; analyzing the metastasis and going back to the primary tumor it turned out to be a transcription factor EB-renal cell carcinoma. The treatment plan included local radiation and systemic therapy. As part of the multimodal approach, tumor samples for genetic assessment were obtained. However, there is no recommended standard therapy for transcription factor EB-renal cell carcinoma. Despite four lines of medical treatment with targeted therapy and one checkpoint inhibitor, all attempts to prolong the patient's survival failed. During the course of this unusual disease, we gained insights which, to the best of our knowledge, were unknown before in the expression of the gene signature linked to autophagy. This might in part explain the resistance to conventional targeted therapy acknowledged in our patient.

  1. Investigation of the roles of T6SS genes in motility, biofilm formation, and extracellular protease Asp production in Vibrio alginolyticus with modified Gateway-compatible plasmids.

    PubMed

    Liu, H; Gu, D; Sheng, L; Wang, Q; Zhang, Y

    2012-07-01

    The aims of this study were to create and evaluate the Gateway-compatible plasmids for investigating the function of genes in Vibrio alginolyticus and other Gram-negative bacteria. In this study, Gateway-compatible plasmids were successfully constructed for rapid and comprehensive function analysis of genes. Taking advantage of these plasmids, the in-frame deletion mutant strains and their complemented strains of five T6SS genes, including dotU1, VEPGS_0008, VEPGS_0011, hcp2 and ppkA2, were obtained. The results illustrated that all the mutant strains showed no significant effects on extracellular protease production, expression of Hcp1, and biofilm formation when compared to the wild-type strain, but in-frame deletion of VEPGS_0008 resulted in obvious biofilm reduction and the complemented strain restored to the level of the wild-type strain. Besides, in-frame deletion of dotU1, VEPGS_0008 and ppkA2 abolished the swarming ability. A set of Gateway-compatible vectors for internal insertion, in-frame deletion and complementation of the target genes is constructed to facilitate the general and rapid function analysis of genes involved in T6SS in Vibrio alginolyticus. The modified Gateway-compatible plasmids greatly facilitate the high-throughput and convenient function analysis of the unidentified genes. No claim to Chinese Government works. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.

  2. Global and local investigations of the electrochemical behavior the T6 heat treated Mg-Zn-RE magnesium alloy thixo-cast

    NASA Astrophysics Data System (ADS)

    Szklarz, Zbigniew; Bisztyga, Magdalena; Krawiec, Halina; Lityńska-Dobrzyńska, Lidia; Rogal, Łukasz

    2017-05-01

    The influence of semi-solid metal processing (SSM called also as thixoforming) of ZE41A magnesium alloy on the electrochemical behavior in 0.1 M NaCl solution was investigated. To describe the corrosion behavior of ZE41A alloy, the electrochemical measurements were conducted in global and local scale for two types of specimens: (1) ingot-feedstock, (2) specimen after thixoforming and T6 treatment. The heat treatment and thixoforming significantly improved mechanical properties of ZE41A alloy. The global corrosion potential is slightly higher for treated sample what is related to the presence of Zr-Zn nanoparticles distributed in solid solution. The corrosion behavior differences between feedstock and thixo-cast after T6 samples are also visible in local scale, what has been revealed by using microcapillary technique. However there is no improvement in corrosion behavior after treatment. Corrosion morphology of the treated sample indicate higher susceptibility to pitting and filiform corrosion. Corrosion rate is also slightly higher.

  3. Assessment of abdominal muscle function in individuals with motor-complete spinal cord injury above T6 in response to transcranial magnetic stimulation.

    PubMed

    Bjerkefors, Anna; Squair, Jordan W; Chua, Romeo; Lam, Tania; Chen, Zhen; Carpenter, Mark G

    2015-02-01

    To use transcranial magnetic stimulation and electromyography to assess the potential for preserved function in the abdominal muscles in individuals classified with motor-complete spinal cord injury above T6. Five individuals with spinal cord injury (C5-T3) and 5 able-bodied individuals. Transcranial magnetic stimulation was delivered over the abdominal region of primary motor cortex during resting and sub-maximal (or attempted) contractions. Surface electromyography was used to record motor-evoked potentials as well as maximal voluntary (or attempted) contractions in the abdominal muscles and the diaphragm. Responses to transcranial magnetic stimulation in the abdominal muscles occurred in all spinal cord injury subjects. Latencies of muscle response onsets were similar in both groups; however, peak-to-peak amplitudes were smaller in the spinal cord injury group. During maximal voluntary (or attempted) contractions all spinal cord injury subjects were able to elicit electromyography activity above resting levels in more than one abdominal muscle across tasks. Individuals with motor-complete spinal cord injury above T6 were able to activate abdominal muscles in response to transcranial magnetic stimulation and during maximal voluntary (or attempted) contractions. The activation was induced directly through corticospinal pathways, and not indirectly by stretch reflex activations of the diaphragm. Transcranial magnetic stimulation and electromyography measurements provide a useful method to assess motor preservation of abdominal muscles in persons with spinal cord injury.

  4. 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.

  5. Experimental comparison of the MIG, friction stir welding, cold metal transfer and hybrid laser-MIG processes for AA 6005-T6 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Caruso, Serafino; Sgambitterra, Emanuele; Rinaldi, Sergio; Gallone, Antonello; Viscido, Lucio; Filice, Luigino; Umbrello, Domenico

    2016-10-01

    In this study, the mechanical properties of welded joints of AA 6005-T6 aluminum alloy obtained with hybrid laser-MIG and cold metal transfer (CMT) welding were analyzed. The performance of hybrid laser-MIG and CMT welded joints were identified using tensile, bending, shear and fatigue life tests. Taking into account the process conditions and requirements, hybrid laser-MIG and CMT welding processes were compared with friction stir welding (FSW) and conventional metal inert gas (MIG) welding processes, shown in a previous work, to understand the advantages and disadvantages of the processes for welding applications of studied Al alloy. Better tensile, bending and shear strength and fatigue life behavior were obtained with hybrid laser-MIG and FSW welded joints compared with conventional MIG processes.

  6. 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.

  7. High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

    NASA Astrophysics Data System (ADS)

    Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

    2018-01-01

    Friction stir welding (FSW) is a cost-effective and high-quality joining process for aluminum alloys (especially heat-treatable alloys) that is historically operated at lower joining speeds (up to hundreds of millimeters per minute). In this study, we present a microstructural analysis of friction stir welded AA7075-T6 blanks with high welding speeds up to 3 M/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. The higher welding speed results in narrower, stronger heat-affected zones (HAZs) and also higher hardness in the nugget zones. The material flow direction in the nugget zone is found to be leaning towards the welding direction as the welding speed increases. Results are coupled with welding parameters and thermal history to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high-speed processing.

  8. 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.

  9. CalR is required for the expression of T6SS2 and the adhesion of Vibrio parahaemolyticus to HeLa cells.

    PubMed

    Zhang, Lingyu; Osei-Adjei, George; Zhang, Ying; Gao, He; Yang, Wenhui; Zhou, Dongsheng; Huang, Xinxiang; Yang, Huiying; Zhang, Yiquan

    2017-08-01

    Vibrio parahaemolyticus expresses one major virulence determinant T6SS2, which is constituted into three putative operons, i.e., VPA1027-1024, VPA1043-1028, and VPA1044-1046. CalR, a LysR-type transcriptional regulator, was originally identified as a repressor of the swarming motility and T3SS1 gene expression. As shown in this study, CalR binds to the promoter-proximal region of each of the three operons to activate their transcription, and moreover, CalR activates the adhesion of V. parahaemolyticus to HeLa cells. In addition, competitive EMSAs demonstrated that CalR acts as an antagonist of H-NS in V. parahaemolyticus. Collectively, these studies confirmed a new physiological role for CalR in V. parahaemolyticus.

  10. 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.

  11. Diagnostic accuracy of common clinical tests for assessing abdominal muscle function after motor-complete spinal cord injury above T6.

    PubMed

    Bjerkefors, A; Squair, J W; Malik, R; Lam, T; Chen, Z; Carpenter, M G

    2015-02-01

    Diagnostic study. The objective of this study was to compare patterns of electromyography (EMG) recordings of abdominal muscle function in persons with motor-complete spinal cord injury (SCI) above T6 and in able-bodied controls, and to determine whether manual examination or ultrasound measures of muscle activation can be accurate alternatives to EMG. Research center focused on SCI and University laboratory, Vancouver, Canada. Thirteen people with SCI (11 with American Spinal Injury Association Impairment Scale (AIS) A and 2 AIS B; C4-T5), and 13 matched able-bodied participants volunteered for the study. Participants completed trunk tasks during manual examination of the abdominal muscles and then performed maximal voluntary isometric contractions, while EMG activity and muscle thickness changes were recorded. The frequency of muscle responses detected by manual examination and ultrasound were compared with detection by EMG (sensitivity and specificity). All individuals with SCI were able to elicit EMG activity above resting levels in at least one abdominal muscle during one task. In general, the activation pattern was task specific, confirming voluntary control of the muscles. Ultrasound, when compared with EMG, showed low sensitivity but was highly specific in its ability to detect preserved abdominal muscle function in persons with SCI. Conversely, manual examination was more sensitive than ultrasound but showed lower specificity. The results from this study confirm preserved voluntary abdominal muscle function in individuals classified with motor-complete SCI above T6 and highlight the need for further research in developing more accurate clinical measures to diagnose the level of trunk muscle preservation in individuals with SCI.

  12. Switching from antiferromagnetic to ferromagnetic coupling in heptanuclear [M(t)6M(c)](n+) complexes by going from an achiral to a chiral triplesalen ligand.

    PubMed

    Mukherjee, Chandan; Hoeke, Veronika; Stammler, Anja; Bögge, Hartmut; Schnack, Jürgen; Glaser, Thorsten

    2014-07-07

    The chiral triplesalen ligand H6chand(RR) has been used to synthesize the chiral heptanuclear complexes [{(chand(RR))Mn(III)3}2{Fe(II)(CN)6}](ClO4)2 ((RR)[Mn(III)6Fe(II)](ClO4)2) and [{(chand(RR))Fe(III)3}2{Fe(II)(CN)6}](ClO4)2 ((RR)[Fe(III)6Fe(II)](ClO4)2), which have been characterized by single-crystal X-ray diffraction, mass spectrometry, elemental analysis, FT-IR, Mössbauer, and UV-vis spectroscopies, electrochemistry, as well as DC and AC magnetic susceptibility measurements. The half-wave potential of the Fe(III)/Fe(II) couple in (RR)[Mn(III)6Fe(II)](2+) and (RR)[Fe(III)6Fe(II)](2+) is E1/2 = +0.21 and +0.75 V vs. Fc(+)/Fc, respectively, which (i) corresponds to a strong stabilization of the reduced Fe(II) species compared to the redox couple of free [Fe(II/III)(CN)6](4-/3-) and (ii) indicates a significant difference of the electronic coupling with the {(chand(RR))M(t)}(3+) units (M(t) = Mn(III), Fe(III)). Analysis of the DC magnetic data (μeffvs. T, VTVH) of both complexes by a full-matrix diagonalization of the spin-Hamiltonian including isotropic exchange, zero-field splitting with full consideration of the relative orientation of the D tensors and Zeeman interactions reveals ferromagnetic interactions of JMn-Mn = +0.17 ± 0.02 cm(-1) with DMn = -3.4 ± 0.3 cm(-1) for (RR)[Mn(III)6Fe(II)](2+) and JFe-Fe = +0.235 ± 0.005 cm(-1) with DFe = 0 for (RR)[Fe(III)6Fe(II)](2+). The comparison of the molecular structures of (RR)[Mn(III)6Fe(II)](2+) and (RR)[Fe(III)6Fe(II)](2+) with those of the heptanuclear complexes [M(t)6M(c)](n+) using the achiral triplesalen ligand (talen(t-Bu2))(6-) reveals significant differences in the ligand folding, smaller C-C bond distances in the central phloroglucinol ring and larger HOMA values. This indicates more aromatic character and less heteroradialene contribution in (RR)[Mn(III)6Fe(II)](2+) and (RR)[Fe(III)6Fe(II)](2+), which explains the switching from antiferromagnetic coupling in [M(t)6M(c)](n+) to ferromagnetic

  13. Determination of forming limit diagrams of AA6013-T6 aluminum alloy sheet using a time and position dependent localized necking criterion

    NASA Astrophysics Data System (ADS)

    Dicecco, S.; Butcher, C.; Worswick, M.; Boettcher, E.; Chu, E.; Shi, C.

    2016-11-01

    The forming limit behaviour of AA6013-T6 aluminium alloy sheet was characterized under isothermal conditions at room temperature (RT) and 250°C using limiting dome height (LDH) tests. Full field strain measurements were acquired throughout testing using in situ stereoscopic digital image correlation (DIC) techniques. Limit strain data was generated from the resulting full field strain measurements using two localized necking criteria: ISO12004- 2:2008 and a time and position dependent criterion, termed the “Necking Zone” (NZ) approach in this paper, introduced by Martinez-Donaire et al. (2014). The limit strains resulting from the two localization detection schemes were compared. It was found that the ISO and NZ limit strains at RT are similar on the draw-side of the FLD, while the NZ approach yields a biaxial major limit strain 14.8% greater than the ISO generated major limit strain. At 250°C, the NZ generated major limit strains are 31-34% greater than the ISO generated major limit strains for near uniaxial, plane strain and biaxial loading conditions, respectively. The significant variance in limit strains between the two methodologies at 250°C highlights the need for a validation study regarding warm FLC determination.

  14. High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

    SciTech Connect

    Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri

    2017-11-20

    Friction-stir-welding (FSW) is a cost-effective and high quality joining process for aluminum alloys (especially heat-treatable allo ys) that has been applied successfully in the aerospace industry. However, the full potential of FSW on more cost-sensitive applications is still limited by the production rate, namely the welding speed of the process. The majority of literature evaluating FSW of aluminum alloys is based on welds made in the range of welding speeds around hundreds of millimeters per minute, and only a handful are at a moderate speed of 1 m/min. In this study we present a microstructural analysis of friction stir weldedmore » AA7075-T6 blanks with welding speeds up to 3 m/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. Results are coupled with welding parameters to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high speed processing.« less

  15. 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

  16. 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.

  17. 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.

  18. 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

    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

  19. A method to reduce the rejection rate for low performance at the acceptance test of PWC PT6T-6 overhauled power sections

    SciTech Connect

    Colantuoni, S.; Mainiero, G.; Esposito, A.

    1996-04-01

    Alfa Romeo Avio is involved in the overhaul process of the Pratt and Whitney of Canada PT6T-6 for the helicopter fleet of the Italian Army and civil services. The overhauled power sections suffered from a high rejection rate (about 40 percent) for low performance at the acceptance test. Alfa Romeo Avio R and D investigated the causes and developed a method to reduce the rejection rate. A first contribution to the decision support method for the selection of the optimal engine configuration can be obtained from engine thermodynamic cycle simulation, which gives indications on the behavior of the average overhauled power section. In this paper the authors also describe a statistical model based on a cause/effect correlation between power section assembly variables and performance parameters. A simulation procedure, based on the statistical model, estimates the influence of the configuration assembly data on the power section performance parameters. A careful application of both statistical and thermodynamic models gives predictions on the optimum matching of turbine nozzle size to reach the target performance at the engine acceptance test. The method has been tested on the field during the last two years and a reduction in the rejection rate at the acceptance test to 18 percent has been obtained.

  20. 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. © 2015 Wiley Periodicals, Inc.

  1. 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

  2. Microstructure and mechanical properties of 2024-T3 and 7075-T6 aluminum alloys and austenitic stainless steel 304 after being exposed to hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Sofyan, Nofrijon Bin Imam

    The effect of hydrogen peroxide used as a decontaminant agent on selected aircraft metallic materials has been investigated. The work is divided into three sections; bacterial attachment behavior onto an austenitic stainless steel 304 surface; effect of decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials of two aluminum alloys, i.e. 2024-T3 and 7075-T6, and an austenitic stainless steel 304 as used in galley and lavatory surfaces; and copper dissolution rate into hydrogen peroxide. With respect to bacterial attachment, the results show that surface roughness plays a role in the attachment of bacteria onto metallic surfaces at certain extent. However, when the contact angle of the liquid on a surface increased to a certain degree, detachment of bacteria on that surface became more difficult. In its relation to the decontamination process, the results show that a corrosion site, especially on the austenitic stainless steel 304 weld and its surrounding HAZ area, needs more attention because it could become a source or a harborage of bio-contaminant agent after either incidental or intentional bio-contaminant delivery. On the effect of the decontamination process on the microstructure and mechanical properties of aircraft metallic structural materials, the results show that microstructural effects are both relatively small in magnitude and confined to a region immediately adjacent to the exposed surface. No systematic effect is found on the tensile properties of the three alloys under the conditions examined. The results of this investigation are promising with respect to the application of vapor phase hydrogen peroxide as a decontaminant agent to civilian aircraft, in that even under the most severe circumstances that could occur; only very limited damage was observed. The results from the dissolution of copper by concentrated liquid hydrogen peroxide showed that the rate of copper dissolution increased for

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

    PubMed Central

    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

    2016-01-01

    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

  4. BCL2 promotor methylation and miR-15a/16-1 upregulation is associated with sanguinarine-induced apoptotic death in rat HSC-T6 cells.

    PubMed

    Zhang, Da-Sheng; Li, Yuan-Yi; Chen, Xiao-Jun; Li, Yu-Juan; Liu, Zhao-Ying; Xie, Wen-Jian; Sun, Zhi-Liang

    2015-01-01

    Previous studies show that several pathways are involved in sanguinarine-induced apoptotic cell death, including AKT downregulation, inhibition of NF-kB activation, mediation of ROS production, downregulation of anti-apoptosis proteins XIAP and cIAP-1, upregulation of BAX, and downregulation of BCL2. In this study, we found out that the quenching of ROS generation by N-acetyl-l-cysteine (NAC), a scavenger of ROS, reversed sanguinarine-induced apoptosis effects, also we found out that sanguinarine-induced rat hepatic stellate T6 cells (HSC-T6 cells) apoptosis was correlated with the generation of increased ROS, which was followed by the activation of caspase-8 (-3, -6, and -9), and the decreasing in the miltochondrial membrane potential (MMP) and the down-regulation of anti-apoptotic protein Bcl-2. It is not clear whether BCL2's downregulation relates to its promoter methylation and miR-15a/16-1 expression which can bind to BCL2 3'-UTR (un-translation reagon). We showed that sanguinarine-induced down regulation of BCL2 was associated with the increased methylation rate of BCL2 promotor district and the increased expression of miR-15a/16-1. HSC-T6 cells treatment with 5-Aza-2'-deoxycytidine (5'-Aza-CdR) impeded sanguinarine-induced BCL2 promotor district methylation and recovered BCL2's expression. Over expression of BCL2 using pEGFP-N1 vector decreased sanguinarine-induced HSC-T6 cells apoptotic death significantly but not completely. These observations clearly showed that BCL2 down regulation was associated with its promoter methylation and miR-15a/16-1 upregulation in sanguinarine-induced Rat HSC-T6 cells. Copyright © 2014 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

  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. The effect of thermal exposure on the mechanical properties of 2099-T6 die forgings, 2099-T83 extrusions, 7075-T7651 plate, 7085-T7452 die forgings, 7085-T7651 plate, and 2397-T87 plate aluminum alloys

    NASA Astrophysics Data System (ADS)

    Jabra, J.; Romios, M.; Lai, J.; Lee, E.; Setiawan, M.; Ogren, J. R.; Clark, R.; Oppenheim, T.; Es-Said, O. S.; Lee, E. W.; Abourialy, N.; Frazier, W. E.; Witters, J.

    2006-10-01

    Aluminum alloys 2099-T6 die forgings, 2099-T83 extrusions, 7075-T7651 plate, 7085-T7452 die forgings, 7085-T7651 plate, and 2397-T87 plate were thermally exposed at temperatures of 180 °C (350 °F), 230 °C (450 °F), and 290 °C (550 °F) for 0.1, 0.5, 2, 10, 100, and 1000 h. The purpose of this study was to determine the effect of thermal exposure on the mechanical properties and electrical conductivity of these alloys. The data shows that higher temperatures and longer exposure times generally resulted in decreased strength and hardness and increased percent elongation and electrical conductivity.

  7. Description of the smallest critical region for Dandy-Walker malformation in chromosome 13 in a girl with a cryptic deletion related to t(6;13)(q23;q32).

    PubMed

    Mademont-Soler, Irene; Morales, Carme; Armengol, Lluís; Soler, Anna; Sánchez, Aurora

    2010-09-01

    We report on a girl with mild dysmorphic facial features, Dandy-Walker malformation (DWM), iris coloboma, profound hearing loss, and hyperlaxity of skin and joints, whose karyotype is 46,XX,t(6;13)(q23;q32)dn and who has a cryptic imbalance at the 13q32 translocation breakpoint assessed by array-CGH. Our patient has many clinical manifestations in common with those of the previously reported cases of 13q32 deletions, which suggests that at least part of the abnormal phenotype is probably due to the imbalance. The recurrent finding of DWM among patients with 13q deletions has led to the suggestions that candidate gene/s for its development are on chromosome 13. We describe the smallest 13q deletion associated to DWM, which allows further narrowing of the previously established critical region for this brain malformation to 13q32.2-32.3. Among the few genes of the deleted region, ZIC2 and ZIC5 seem the most plausible candidates, which is in keeping with some previous reports. This work also illustrates the usefulness of array-CGH platforms in the identification of cryptic imbalances in carriers of apparently balanced rearrangements with abnormal phenotypes.

  8. Structural insights into the T6SS effector protein Tse3 and the Tse3-Tsi3 complex from Pseudomonas aeruginosa reveal a calcium-dependent membrane-binding mechanism.

    PubMed

    Lu, Defen; Shang, Guijun; Zhang, Heqiao; Yu, Qian; Cong, Xiaoyan; Yuan, Jupeng; He, Fengjuan; Zhu, Chunyuan; Zhao, Yanyu; Yin, Kun; Chen, Yuanyuan; Hu, Junqiang; Zhang, Xiaodan; Yuan, Zenglin; Xu, Sujuan; Hu, Wei; Cang, Huaixing; Gu, Lichuan

    2014-06-01

    The opportunistic pathogen Pseudomonas aeruginosa uses the type VI secretion system (T6SS) to deliver the muramidase Tse3 into the periplasm of rival bacteria to degrade their peptidoglycan (PG). Concomitantly, P. aeruginosa uses the periplasm-localized immunity protein Tsi3 to prevent potential self-intoxication caused by Tse3, and thus gains an edge over rival bacteria in fierce niche competition. Here, we report the crystal structures of Tse3 and the Tse3-Tsi3 complex. Tse3 contains an annexin repeat-like fold at the N-terminus and a G-type lysozyme fold at the C-terminus. One loop in the N-terminal domain (Loop 12) and one helix (α9) from the C-terminal domain together anchor Tse3 and the Tse3-Tsi3 complex to membrane in a calcium-dependent manner in vitro, and this membrane-binding ability is essential for Tse3's activity. In the C-terminal domain, a Y-shaped groove present on the surface likely serves as the PG binding site. Two calcium-binding motifs are also observed in the groove and these are necessary for Tse3 activity. In the Tse3-Tsi3 structure, three loops of Tsi3 insert into the substrate-binding groove of Tse3, and three calcium ions present at the interface of the complex are indispensable for the formation of the Tse3-Tsi3 complex. © 2014 John Wiley & Sons Ltd.

  9. 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

  10. Informatics-Aided Density Functional Theory Study on the Li Ion Transport of Tavorite-Type LiMTO4F (M(3+)-T(5+), M(2+)-T(6+)).

    PubMed

    Jalem, Randy; Kimura, Mayumi; Nakayama, Masanobu; Kasuga, Toshihiro

    2015-06-22

    The ongoing search for fast Li-ion conducting solid electrolytes has driven the deployment surge on density functional theory (DFT) computation and materials informatics for exploring novel chemistries before actual experimental testing. Existing structure prototypes can now be readily evaluated beforehand not only to map out trends on target properties or for candidate composition selection but also for gaining insights on structure-property relationships. Recently, the tavorite structure has been determined to be capable of a fast Li ion insertion rate for battery cathode applications. Taking this inspiration, we surveyed the LiMTO4F tavorite system (M(3+)-T(5+) and M(2+)-T(6+) pairs; M is nontransition metals) for solid electrolyte use, identifying promising compositions with enormously low Li migration energy (ME) and understanding how structure parameters affect or modulate ME. We employed a combination of DFT computation, variable interaction analysis, graph theory, and a neural network for building a crystal structure-based ME prediction model. Candidate compositions that were predicted include LiGaPO4F (0.25 eV), LiGdPO4F (0.30 eV), LiDyPO4F (0.30 eV), LiMgSO4F (0.21 eV), and LiMgSeO4F (0.11 eV). With chemical substitutions at M and T sites, competing effects among Li pathway bottleneck size, polyanion covalency, and local lattice distortion were determined to be crucial for controlling ME. A way to predict ME for multiple structure types within the neural network framework was also explored.

  11. T-6A Texan II Systems Engineering Case Study

    DTIC Science & Technology

    2010-01-01

    Onboard Oxygen Generating System, which, together, permits training at higher, less congested altitudes. Figure 3 depicts the cockpit layout ...of view commensurate with the JPPT syllabus training requirements Same Figure 9. JPATS Key Performance Parameters48...include provisions for light armament to be used in the more advanced stages of the training syllabus . As with the Canadian buy, the SPO was not directly

  12. 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).

  13. Renal cell carcinomas with t(6;11)(p21;q12): A clinicopathologic study emphasizing unusual morphology, novel alpha-TFEB gene fusion point, immunobiomarkers, and ultrastructural features, as well as detection of the gene fusion by fluorescence in situ hybridization.

    PubMed

    Rao, Qiu; Liu, Biao; Cheng, Liang; Zhu, Yun; Shi, Qun-Li; Wu, Bo; Jiang, Shao-Jun; Wang, Yan; Wang, Xuan; Yu, Bo; Zhang, Ru-Song; Ma, Heng-Hui; Lu, Zhen-Feng; Tu, Pin; Wang, Jian-Dong; Zhou, Xiao-Jun

    2012-09-01

    Renal cell carcinomas (RCCs) with t(6;11)(p21;q12) are extremely rare and characterized by specific chromosome translocation, involving the transcription factor EB (TFEB). Fewer than 30 cases have been described in the literature. We examined 7 additional cases of this rare tumor by clinicopathologic, immunohistochemical, molecular, and ultrastructural analyses. Four tumors had the typical morphologic features of TFEB RCCs, whereas 3 cases demonstrated uncommon morphologic features, mimicking epithelioid angiomyolipoma, chromophobe cell RCC, and clear cell RCC, respectively. Immunohistochemically, aside from TFEB and cathepsin K, kidney-specific cadherin was another sensitive and relatively specific marker for TFEB RCCs, supporting a distal nephron origin for these renal tumors. We also observed different ultrastructures including mitochondrion with areas of lipofuscin pigment in the smaller cells in these cases. An identical Alpha-TFEB fusion gene, 486 bp, was identified in 2 cases. In addition to the polymerase chain reaction method, we also developed a fluorescence in situ hybridization assay to serve as a cost-effective and time-efficient diagnostic tool. We detected a TFEB gene rearrangement in all 7 cases using the fluorescence in situ hybridization method. TFEB RCC seemed to be an indolent tumor. During a mean follow-up of 31 months, none of the cases developed tumor recurrence, progression, or metastasis.

  14. Crack Initiation and Growth Behavior at Corrosion Pit in 7075-T6 High Strength Aluminum Alloy

    DTIC Science & Technology

    2013-06-01

    in Fig. 3.6. These steel chambers sandwich the test specimen and the two halves are bolted together and sealed with rubber gaskets to ensure a water...of Fatigue, 31:1031–1038, 2009. ISSN 0142-1123. [30] Nan, Z.Y., S. Ishihara, and T. Goshima. “Corrosion fatigue behavior of extruded magnesium alloy

  15. Initial, Cockpit Anthropometric Assessment of U.S. Navy T-6 Life Support Equipment

    DTIC Science & Technology

    2007-11-05

    as in a Frankfurt plane not specified. Lower leg clearance was measured from shin line and lower instrument edge of main panel. Ejection clearance...demonstrate the complexity of body dimensions, seat adjustments in just one plane and how they affect other accommodation, function, and safety; truly...Manual (14) and Student Guide with “Top of the helmet shall be at or below the canopy breaker. Without parallax, the Plane Captain or other

  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. 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.

  18. 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.

  19. Environmental Assessment T-1, T-6, and T-37 Aircraft Operations at Perry Municipal Airport

    DTIC Science & Technology

    2006-04-01

    monoxide (CO), sulfur dioxide (S02), and lead (Pb ). Ozone (ground-level ozone), which is a. major component of" smog ," is a secondary pollutant formed in...the atmosphere by photochemical reactions involving previously emitted pollutants or precursors. Ozone precursors are mainly nitrogen oxides (NOx...containing at least carbon and hydrogen) that participate in photochemical reactions and include carbonaceous compounds except metallic carbonates

  20. 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.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  2. Crack Initiation and Growth Behavior at Corrosion Pit in 7075-T6 Under Biaxial and Uniaxial Fatigue

    DTIC Science & Technology

    2014-06-19

    Biaxial Testing machine was used for the experiments. The System consisted of four actuators and load cells, hydraulic grips and fixtures, rubber ...were sealed with rubber gaskets to prevent leakage. Then the saltwater was added through the holes at the top of the chambers. The hole, the...Biaxial Test System", 100-179-028, 2007. [38] Nan, Z.Y., S. Ishihara, and T. Goshima. "Corrosion fatigue behavior of extruded magnesium alloy AZ31

  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.

  4. Mitigating Diminishing Manufacturing Sources Material Shortages (DMS/MS) and Obsolescence for the T-6 Canopy Fracturing Initiation System (CFIS)

    DTIC Science & Technology

    2012-03-01

    electric crystals that generated a small amount of electricity when pressure was applied during lever actuation, setting off the light bulbs , and...norm. It is doubtful we will ever see again an example similar like the ubiquitous light bulb that’s still in worldwide use in virtually the same...individual bulbs now used in the module with the proposed annular design (Figure 9), since the annular internal volume produces higher light output

  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. Identifying Combination of Friction Stir Welding Parameters to Maximize Strength of Lap Joints of AA2014-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    AA2014 aluminum alloy (Al-Cu alloy) has been widely utilized in fabrication of lightweight structures like aircraft structures, demanding high strength to weight ratio and good corrosion resistance. The fusion welding of these alloys will lead to solidification problems such as hot cracking. Friction stir welding is a new solid state welding process, in which the material being welded does not melt and recast. Lot of research works have been carried out by many researchers to optimize process parameters and establish empirical relationships to predict tensile strength of friction stir welded butt joints of aluminum alloys. However, very few investigations have been carried out on friction stir welded lap joints of aluminum alloys. Hence, in this investigation, an attempt has been made to optimize friction stir lap welding (FSLW) parameters to attain maximum tensile strength using statistical tools such as design of experiment (DoE), analysis of variance (ANOVA), response graph and contour plots. By this method, it is found that maximum tensile shear fracture load of 12.76 kN can be achieved if a joint is made using tool rotational speed of 900 rpm, welding speed of 110 mm/min, tool shoulder diameter of 12 mm and tool tilt angle of 1.5°.

  7. Corrosion Fatigue Crack Growth Behavior at Notched Hole in 7075 T6 Under Different Biaxial Stress Ratios

    DTIC Science & Technology

    2016-08-18

    biaxiality on fatigue crack growth behavior, which is what has been lacking in this field up to now. Cruciform specimens were made from a 3.18 mm thick...missing part from the previous studies in this field . 6 II. Background 2.1 Fatigue There has been a steady increase in the number of military...types such as torsion , bending, and rotation [34]. Fatigue in metals begins at surface locations with concentrated stress. It first begins with

  8. On binding specificity of (6-4) photolyase to a T(6-4)T DNA photoproduct*

    NASA Astrophysics Data System (ADS)

    Jepsen, Katrine Aalbæk; Solov'yov, Ilia A.

    2017-06-01

    Different factors lead to DNA damage and if it is not repaired in due time, the damaged DNA could initiate mutagenesis and cancer. To avoid this deadly scenario, specific enzymes can scavenge and repair the DNA, but the enzymes have to bind first to the damaged sites. We have investigated this binding for a specific enzyme called (6-4) photolyase, which is capable of repairing certain UV-induced damage in DNA. Through molecular dynamics simulations we describe the binding between photolyase and the DNA and reveal that several charged amino acid residues in the enzyme, such as arginines and lysines turn out to be important. Especially R421 is crucial, as it keeps the DNA strands at the damaged site inside the repair pocket of the enzyme separated. DNA photolyase is structurally highly homologous to a protein called cryptochrome. Both proteins are biologically activated similarly, namely through flavin co-factor photoexcitation. It is, however, striking that cryptochrome cannot repair UV-damaged DNA. The present investigation allowed us to conclude on the small but, apparently, critical differences between photolyase and cryptochrome. The performed analysis gives insight into important factors that govern the binding of UV-damaged DNA and reveal why cryptochrome cannot have this functionality.

  9. VizieR Online Data Catalog: Brown dwarfs with spectral type later than T6 (Leggett+, 2017)

    NASA Astrophysics Data System (ADS)

    Leggett, S. K.; Tremblin, P.; Esplin, T. L.; Luhman, K. L.; Morley, C. V.

    2018-01-01

    We present the new GNIRS and FLAMINGOS-2 spectra and the new NIRI photometry in section 4 (see also table 1). We obtained a 0.95<=λ(um)<=2.5 spectrum using GNIRS at Gemini North on 2016 December 24 and 25 via program GN-2016B-Q-46 for WISEAJ041022.75+150247.9 with R~700. We also obtained near-infrared spectra for WISEJ071322.55-291751.9 and WISEAJ114156.67-332635.5 using FLAMINGOS-2 at Gemini South on 2017 February 3 and 7, via program GS-2017A-FT-2. The JH grism was used giving R~600. We obtained photometry for WISE J085510.83-071442.5 on Gemini North using NIRI at Y and CH4(short) via program GN-2016A-Q-50, and at M' via program GN-2016A-FT-10 between 2015 December and 2016 March. The M' data for a sample of T and Y dwarfs was obtained via program GN-2016B-Q-46 using NIRI on Gemini North. Finally, we obtained H data for the Y1 WISEA J064723.24-623235.4 using FLAMINGOS-2 on Gemini South, which were presented in Leggett+ (2013ApJ...763..130L). We also obtained new photometry from HST/WFC3, ESO VLT HAWK-I and Spitzer/IRAC and WISE archives; see section 5 and tables 2 and 3. (7 data files).

  10. Mixed Mode Stable Tearing of Thin Sheet Al 6061-T6 Specimens: Experimental Measurements and Finite Element Simulations using a Modified Mohr-Coulomb Fracture Criterion

    DTIC Science & Technology

    2010-11-01

    finite element simulations using a modified Mohr - Coulomb fracture criterion Yaning Li · Tomasz Wierzbicki · Michael A. Sutton · Junhui Yan · Xiaomin...experi- mental and computational approach with a Modified Mohr Coulomb (MMC) fracture criterion employing post-initiation element softening is used to...experiments · Modified Mohr - Coulomb criterion · Numerical simulations 1 Introduction The problem of ductile crack initiation and propagation for a pre-cracked

  11. 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.

  12. 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

  13. Effect of Precipitation During Quenching on the Prediction of the Mechanical Properties of Al-5 Pct Cu Alloy After T6 Treatment

    NASA Astrophysics Data System (ADS)

    Hu, Yisen; Wang, Gang; Wang, Wenguang; Rong, Yiming

    2017-11-01

    The mechanical properties of Al-5 pct Cu cast alloy, one of the heat-treatable aluminum alloys, depend on the quenching rate and aging conditions. The effect of precipitation during quenching cannot be ignored for large and thick-walled components, although it is generally assumed that no precipitates form during cooling. In this article, a non-isokinetic model, considering the strengthening effects of precipitation during quenching and aging, was proposed to describe the evolution of minimum strength based on fully precipitating tests and transmission electron microscopy observations. Moreover, a comprehensive quench factor analysis, integrated with the non-isokinetic model, was conducted for the Al-5 pct Cu cast alloy using isothermal quench tests. Finally, the integrated model of the mechanical property was validated under various quenching conditions, including water at 353 K (80 °C), air at room temperature and furnace cooling. It was shown that the prediction can be extended to an 85 pct loss of property.

  14. Enhancing Friction Stir Weldability of 6061-T6 Al and AZ31B Mg Alloys Assisted by External Non-rotational Shoulder

    NASA Astrophysics Data System (ADS)

    Ji, Shude; Huang, Ruofei; Meng, Xiangchen; Zhang, Liguo; Huang, Yongxian

    2017-05-01

    In order to increase cooling rate and then reduce the amounts of intermetallic compounds, external non-rotational shoulder tool system derived from traditional tool in friction stir welding was used to join dissimilar Al and Mg alloys. In this study, based on the external non-rotational shoulder, the weldability of Al and Mg alloys was significantly improved. The non-rotational shoulder tool is propitious to make more materials into weld, increase cooling rate and then reduce material adhesion of rotational pin, obtaining sound joint with smaller flashes and smooth surface. Importantly, the thickness of intermetallic compounds layer is reduced compared with traditional tool. Meanwhile, hardness values of dissimilar joint present uneven distribution, resulting from complex intercalated structures in nugget zone (NZ) featured by intermetallic compound layers and fine recrystallized Mg and Al grains. Compared with traditional tool, non-rotational shoulder is beneficial to higher tensile properties of joint. Due to the intermetallic compound layer formed in the interface of Al-Mg, the welding joint easily fractures at the NZ, presenting the typical brittle fracture mode.

  15. Effect of Stress Ratio on Fatigue Crack Growth Rate at Notched Hole in 7075-T6 Aluminum Alloy Under Biaxial Fatigue

    DTIC Science & Technology

    2016-08-18

    and corrosion. This approach has been used to delay crack in structure in aerospace field [26]. In addition, laterally many studies have described...loading conditions. And it is a link between previous studies and future studies in the field . II. Background 2.1 Fatigue Since fracture mechanics...steady, but other forms of stresses such as rotation, torsion , pending can lead to fatigue failure [5,34]. Fatigue crack start as invisible microcrack

  16. Galvanic Corrosion of Al-7075-T6 and Steel-4340 Coupled to Brass QQ-B- 626,360 and Al-7075-T6 Coupled to Steel-4130 and Steel-4340: Exposure to Aqueous NaCl and Salt-Fog Environments

    DTIC Science & Technology

    1986-06-30

    unaffected. In addition to the discussion of experimental r ts, a theoretical tretment relating galvanic currents to observed corrosion rate are... water tank in your home can be trouble.some if a steel tank is connected to copper tubing. Dissimilar metal corrosion is a persistent problem faced by...Chromium stainless steel. 13% Cr (active)ECast iron [Steel or iron 2024 aluminum (4.5 Cu. 1.5 Mg . 0.6 Mn) Active or4Cadmium anodic Commercially pure

  17. 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 Central

    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 T6SSSPI-6 and T6SSSPI-19. This study has determined the contribution of T6SSSPI-6 and T6SSSPI-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 (∆T6SSSPI-6/∆T6SSSPI-19) presents a strong colonization defect in cecum of chickens, similar to the defect observed for the ∆T6SSSPI-6 mutant, suggesting that this serotype requires a functional T6SSSPI-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 T6SSSPI-19 was not necessary for colonization of either chickens or mice. Transfer of T6SSSPI-6, but not T6SSSPI-19, restored the ability of the double mutant to colonize both animal hosts. Our data indicate that Salmonella Dublin requires only the T6SSSPI-6 for efficient colonization of mice and chickens, and that the T6SSSPI-6 and T6SSSPI-19 are not functionally redundant. PMID:24405577

  18. Vibrio parahaemolyticus Type VI Secretion System 1 Is Activated in Marine Conditions to Target Bacteria, and Is Differentially Regulated from System 2

    PubMed Central

    Salomon, Dor; Gonzalez, Herman; Updegraff, Barrett L.; Orth, Kim

    2013-01-01

    Vibrio parahaemolyticus is a marine bacterium that thrives in warm climates. It is a leading cause of gastroenteritis resulting from consumption of contaminated uncooked shellfish. This bacterium harbors two putative type VI secretion systems (T6SS). T6SSs are widespread protein secretion systems found in many Gram-negative bacteria, and are often tightly regulated. For many T6SSs studied to date, the conditions and cues, as well as the regulatory mechanisms that control T6SS activity are unknown. In this study, we characterized the environmental conditions and cues that activate both V. parahaemolyticus T6SSs, and identified regulatory mechanisms that control T6SS gene expression and activity. We monitored the expression and secretion of the signature T6SS secreted proteins Hcp1 and Hcp2, and found that both T6SSs are differentially regulated by quorum sensing and surface sensing. We also showed that T6SS1 and T6SS2 require different temperature and salinity conditions to be active. Interestingly, T6SS1, which is found predominantly in clinical isolates, was most active under warm marine-like conditions. Moreover, we found that T6SS1 has anti-bacterial activity under these conditions. In addition, we identified two transcription regulators in the T6SS1 gene cluster that regulate Hcp1 expression, but are not required for immunity against self-intoxication. Further examination of environmental isolates revealed a correlation between the presence of T6SS1 and virulence of V. parahaemolyticus against other bacteria, and we also showed that different V. parahaemolyticus isolates can outcompete each other. We propose that T6SS1 and T6SS2 play different roles in the V. parahaemolyticus lifestyles, and suggest a role for T6SS1 in enhancing environmental fitness of V. parahaemolyticus in marine environments when competing for a niche in the presence of other bacterial populations. PMID:23613791

  19. 49 CFR 173.302 - Filling of cylinders with nonliquefied (permanent) compressed gases.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... only by motor vehicle, rail car, or cargo-only aircraft. (e) DOT 3AL cylinders manufactured of 6351-T6... occur while filling cylinders manufactured of aluminum alloy 6351-T6 used in self-contained underwater...

  20. 49 CFR 173.302 - Filling of cylinders with nonliquefied (permanent) compressed gases.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... only by motor vehicle, rail car, or cargo-only aircraft. (e) DOT 3AL cylinders manufactured of 6351-T6... occur while filling cylinders manufactured of aluminum alloy 6351-T6 used in self-contained underwater...

  1. 49 CFR 173.302 - Filling of cylinders with nonliquefied (permanent) compressed gases.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... only by motor vehicle, rail car, or cargo-only aircraft. (e) DOT 3AL cylinders manufactured of 6351-T6... occur while filling cylinders manufactured of aluminum alloy 6351-T6 used in self-contained underwater...

  2. 49 CFR 173.302 - Filling of cylinders with nonliquefied (permanent) compressed gases.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... only by motor vehicle, rail car, or cargo-only aircraft. (e) DOT 3AL cylinders manufactured of 6351-T6... occur while filling cylinders manufactured of aluminum alloy 6351-T6 used in self-contained underwater...

  3. RsmA and AmrZ orchestrate the assembly of all three type VI secretion systems in Pseudomonas aeruginosa.

    PubMed

    Allsopp, Luke P; Wood, Thomas E; Howard, Sophie A; Maggiorelli, Federica; Nolan, Laura M; Wettstadt, Sarah; Filloux, Alain

    2017-07-18

    The type VI secretion system (T6SS) is a weapon of bacterial warfare and host cell subversion. The Gram-negative pathogen Pseudomonas aeruginosa has three T6SSs involved in colonization, competition, and full virulence. H1-T6SS is a molecular gun firing seven toxins, Tse1-Tse7, challenging survival of other bacteria and helping P. aeruginosa to prevail in specific niches. The H1-T6SS characterization was facilitated through studying a P. aeruginosa strain lacking the RetS sensor, which has a fully active H1-T6SS, in contrast to the parent. However, study of H2-T6SS and H3-T6SS has been neglected because of a poor understanding of the associated regulatory network. Here we performed a screen to identify H2-T6SS and H3-T6SS regulatory elements and found that the posttranscriptional regulator RsmA imposes a concerted repression on all three T6SS clusters. A higher level of complexity could be observed as we identified a transcriptional regulator, AmrZ, which acts as a negative regulator of H2-T6SS. Overall, although the level of T6SS transcripts is fine-tuned by AmrZ, all T6SS mRNAs are silenced by RsmA. We expanded this concept of global control by RsmA to VgrG spike and T6SS toxin transcripts whose genes are scattered on the chromosome. These observations triggered the characterization of a suite of H2-T6SS toxins and their implication in direct bacterial competition. Our study thus unveils a central mechanism that modulates the deployment of all T6SS weapons that may be simultaneously produced within a single cell.

  4. Biotechnology Process Engineering Center at MIT Home

    Science.gov Websites

    ... &6; - &8; &22; )&25;&1;t &6; - &8; &22; )&14;&2;er &6; &1; - &8; &22; Q )'&1; &6; - &8; &22; ) &1;a &6; - ... &6; - &8; &22; )&25;&1;t &6; - &8; &22; )&14;&4;er a &6; - &8; &22; )I&1;t &6; - &8; &22; )&14;&4; ...

  5. Genome-Wide Analysis of Type VI System Clusters and Effectors in Burkholderia Species

    PubMed Central

    Nguyen, Thao Thi; Lee, Hyun-Hee; Park, Inmyoung; Seo, Young-Su

    2018-01-01

    Type VI secretion system (T6SS) has been discovered in a variety of gram-negative bacteria as a versatile weapon to stimulate the killing of eukaryotic cells or prokaryotic competitors. Type VI secretion effectors (T6SEs) are well known as key virulence factors for important pathogenic bacteria. In many Burkholderia species, T6SS has evolved as the most complicated secretion pathway with distinguished types to translocate diverse T6SEs, suggesting their essential roles in this genus. Here we attempted to detect and characterize T6SSs and potential T6SEs in target genomes of plant-associated and environmental Burkholderia species based on computational analyses. In total, 66 potential functional T6SS clusters were found in 30 target Burkholderia bacterial genomes, of which 33% possess three or four clusters. The core proteins in each cluster were specified and phylogenetic trees of three components (i.e., TssC, TssD, TssL) were constructed to elucidate the relationship among the identified T6SS clusters. Next, we identified 322 potential T6SEs in the target genomes based on homology searches and explored the important domains conserved in effector candidates. In addition, using the screening approach based on the profile hidden Markov model (pHMM) of T6SEs that possess markers for type VI effectors (MIX motif) (MIX T6SEs), 57 revealed proteins that were not included in training datasets were recognized as novel MIX T6SE candidates from the Burkholderia species. This approach could be useful to identify potential T6SEs from other bacterial genomes. PMID:29422784

  6. Genome-Wide Analysis of Type VI System Clusters and Effectors inBurkholderiaSpecies.

    PubMed

    Nguyen, Thao Thi; Lee, Hyun-Hee; Park, Inmyoung; Seo, Young-Su

    2018-02-01

    Type VI secretion system (T6SS) has been discovered in a variety of gram-negative bacteria as a versatile weapon to stimulate the killing of eukaryotic cells or prokaryotic competitors. Type VI secretion effectors (T6SEs) are well known as key virulence factors for important pathogenic bacteria. In many Burkholderia species, T6SS has evolved as the most complicated secretion pathway with distinguished types to translocate diverse T6SEs, suggesting their essential roles in this genus. Here we attempted to detect and characterize T6SSs and potential T6SEs in target genomes of plant-associated and environmental Burkholderia species based on computational analyses. In total, 66 potential functional T6SS clusters were found in 30 target Burkholderia bacterial genomes, of which 33% possess three or four clusters. The core proteins in each cluster were specified and phylogenetic trees of three components (i.e., TssC, TssD, TssL) were constructed to elucidate the relationship among the identified T6SS clusters. Next, we identified 322 potential T6SEs in the target genomes based on homology searches and explored the important domains conserved in effector candidates. In addition, using the screening approach based on the profile hidden Markov model (pHMM) of T6SEs that possess markers for type VI effectors (MIX motif) (MIX T6SEs), 57 revealed proteins that were not included in training datasets were recognized as novel MIX T6SE candidates from the Burkholderia species. This approach could be useful to identify potential T6SEs from other bacterial genomes.

  7. Trehalose 6-Phosphate Is Required for the Onset of Leaf Senescence Associated with High Carbon Availability1[W][OA

    PubMed Central

    Wingler, Astrid; Delatte, Thierry L.; O’Hara, Liam E.; Primavesi, Lucia F.; Jhurreea, Deveraj; Paul, Matthew J.; Schluepmann, Henriette

    2012-01-01

    Trehalose 6-phosphate (T6P) is an important regulator of plant metabolism and development. T6P content increases when carbon availability is high, and in young growing tissue, T6P inhibits the activity of Snf1-related protein kinase (SnRK1). Here, strong accumulation of T6P was found in senescing leaves of Arabidopsis (Arabidopsis thaliana), in parallel with a rise in sugar contents. To determine the role of T6P in senescence, T6P content was altered by expressing the bacterial T6P synthase gene, otsA (to increase T6P), or the T6P phosphatase gene, otsB (to decrease T6P). In otsB-expressing plants, T6P accumulated less strongly during senescence than in wild-type plants, while otsA-expressing plants contained more T6P throughout. Mature otsB-expressing plants showed a similar phenotype as described for plants overexpressing the SnRK1 gene, KIN10, including reduced anthocyanin accumulation and delayed senescence. This was confirmed by quantitative reverse transcription-polymerase chain reaction analysis of senescence-associated genes and genes involved in anthocyanin synthesis. To analyze if the senescence phenotype was due to decreased sugar sensitivity, the response to sugars was determined. In combination with low nitrogen supply, metabolizable sugars (glucose, fructose, or sucrose) induced senescence in wild-type and otsA-expressing plants but to a smaller extent in otsB-expressing plants. The sugar analog 3-O-methyl glucose, on the other hand, did not induce senescence in any of the lines. Transfer of plants to and from glucose-containing medium suggested that glucose determines senescence during late development but that the effects of T6P on senescence are established by the sugar response of young plants. PMID:22247267

  8. Molecular detection identified a type six secretion system in Campylobacter jejuni from various sources but not from human cases.

    PubMed

    Siddiqui, F; Champion, O; Akram, M; Studholme, D; Eqani, S A M A S; Wren, B W; Titball, R; Bokhari, H

    2015-05-01

    To determine the presence of the T6SS in Campylobacter jejuni from diverse sources. The recently identified type VI secretion system (T6SS) is a bacterial injection machinery that plays a role in virulence, symbiosis, bacterial interactions and environmental stress responses. This system has been recently discovered in the major enteric pathogen Camp. jejuni. In this study, we used multiplex PCR (mPCR), based on conserved genetic markers of the T6SS, to screen 366 Pakistani Camp. jejuni isolates from humans, poultry, cattle, wildlife or waste-water sources. We identified the T6SS in isolates from all of these sources except humans. The overall prevalence of the T6SS among the isolates was 17/366 (4·6%) and the T6SS positive isolates clustered into four different groups. Transcription of the T6SS genes, determined using RT-PCR, was observed in bacteria cultured at 37 or 42°C but not in 37°C cultures adjusted to pH3. Campylobacter jejuni isolates harbouring T6SS markers genes were identified in livestock and non-livestock sources but in this study we did not identify human diarrhoeal isolates which possessed the T6SS. We demonstrated down-regulation of T6SS in an acidic environment. This study questions the role of the T6SS in human diarrhoeal disease. Moreover this study did not identify a clear association of Camp. jejuni isolates harbouring T6SS with any of the niches tested. Our study highlights the need to establish the role of the T6SS in environmental survival or virulence. © 2015 The Society for Applied Microbiology.

  9. Dual Expression Profile of Type VI Secretion System Immunity Genes Protects Pandemic Vibrio cholerae

    PubMed Central

    Miyata, Sarah T.; Unterweger, Daniel; Rudko, Sydney P.; Pukatzki, Stefan

    2013-01-01

    The Vibrio cholerae type VI secretion system (T6SS) assembles as a molecular syringe that injects toxic protein effectors into both eukaryotic and prokaryotic cells. We previously reported that the V. cholerae O37 serogroup strain V52 maintains a constitutively active T6SS to kill other Gram-negative bacteria while being immune to attack by kin bacteria. The pandemic O1 El Tor V. cholerae strain C6706 is T6SS-silent under laboratory conditions as it does not produce T6SS structural components and effectors, and fails to kill Escherichia coli prey. Yet, C6706 exhibits full resistance when approached by T6SS-active V52. These findings suggested that an active T6SS is not required for immunity against T6SS-mediated virulence. Here, we describe a dual expression profile of the T6SS immunity protein-encoding genes tsiV1, tsiV2, and tsiV3 that provides pandemic V. cholerae strains with T6SS immunity and allows T6SS-silent strains to maintain immunity against attacks by T6SS-active bacterial neighbors. The dual expression profile allows transcription of the three genes encoding immunity proteins independently of other T6SS proteins encoded within the same operon. One of these immunity proteins, TsiV2, protects against the T6SS effector VasX which is encoded immediately upstream of tsiV2. VasX is a secreted, lipid-binding protein that we previously characterized with respect to T6SS-mediated virulence towards the social amoeba Dictyostelium discoideum. Our data suggest the presence of an internal promoter in the open reading frame of vasX that drives expression of the downstream gene tsiV2. Furthermore, VasX is shown to act in conjunction with VasW, an accessory protein to VasX, to compromise the inner membrane of prokaryotic target cells. The dual regulatory profile of the T6SS immunity protein-encoding genes tsiV1, tsiV2, and tsiV3 permits V. cholerae to tightly control T6SS gene expression while maintaining immunity to T6SS activity. PMID:24348240

  10. Altering Trehalose-6-Phosphate Content in Transgenic Potato Tubers Affects Tuber Growth and Alters Responsiveness to Hormones during Sprouting1[C][W

    PubMed Central

    Debast, Stefan; Nunes-Nesi, Adriano; Hajirezaei, Mohammad R.; Hofmann, Jörg; Sonnewald, Uwe; Fernie, Alisdair R.; Börnke, Frederik

    2011-01-01

    Trehalose-6-phosphate (T6P) is a signaling metabolite that regulates carbon metabolism, developmental processes, and growth in plants. In Arabidopsis (Arabidopsis thaliana), T6P signaling is, at least in part, mediated through inhibition of the SNF1-related protein kinase SnRK1. To investigate the role of T6P signaling in a heterotrophic, starch-accumulating storage organ, transgenic potato (Solanum tuberosum) plants with altered T6P levels specifically in their tubers were generated. Transgenic lines with elevated T6P levels (B33-TPS, expressing Escherichia coli osmoregulatory trehalose synthesis A [OtsA], which encodes a T6P synthase) displayed reduced starch content, decreased ATP contents, and increased respiration rate diagnostic for high metabolic activity. On the other hand, lines with significantly reduced T6P (B33-TPP, expressing E. coli OtsB, which encodes a T6P phosphatase) showed accumulation of soluble carbohydrates, hexose phosphates, and ATP, no change in starch when calculated on a fresh weight basis, and a strongly reduced tuber yield. [14C]Glucose feeding to transgenic tubers indicated that carbon partitioning between starch and soluble carbohydrates was not altered. Transcriptional profiling of B33-TPP tubers revealed that target genes of SnRK1 were strongly up-regulated and that T6P inhibited potato tuber SnRK1 activity in vitro. Among the SnRK1 target genes in B33-TPP tubers, those involved in the promotion of cell proliferation and growth were down-regulated, while an inhibitor of cell cycle progression was up-regulated. T6P-accumulating tubers were strongly delayed in sprouting, while those with reduced T6P sprouted earlier than the wild type. Early sprouting of B33-TPP tubers correlated with a reduced abscisic acid content. Collectively, our data indicate that T6P plays an important role for potato tuber growth. PMID:21670224

  11. The Trehalose 6-Phosphate/SnRK1 Signaling Pathway Primes Growth Recovery following Relief of Sink Limitation1[W][OA

    PubMed Central

    Nunes, Cátia; O’Hara, Liam E.; Primavesi, Lucia F.; Delatte, Thierry L.; Schluepmann, Henriette; Somsen, Govert W.; Silva, Anabela B.; Fevereiro, Pedro S.; Wingler, Astrid; Paul, Matthew J.

    2013-01-01

    Trehalose 6-P (T6P) is a sugar signal in plants that inhibits SNF1-related protein kinase, SnRK1, thereby altering gene expression and promoting growth processes. This provides a model for the regulation of growth by sugar. However, it is not known how this model operates under sink-limited conditions when tissue sugar content is uncoupled from growth. To test the physiological importance of this model, T6P, SnRK1 activities, sugars, gene expression, and growth were measured in Arabidopsis (Arabidopsis thaliana) seedlings after transfer to cold or zero nitrogen compared with sugar feeding under optimal conditions. Maximum in vitro activities of SnRK1 changed little, but T6P accumulated up to 55-fold, correlating with tissue Suc content in all treatments. SnRK1-induced and -repressed marker gene expression strongly related to T6P above and below a threshold of 0.3 to 0.5 nmol T6P g−1 fresh weight close to the dissociation constant (4 µm) of the T6P/ SnRK1 complex. This occurred irrespective of the growth response to Suc. This implies that T6P is not a growth signal per se, but through SnRK1, T6P primes gene expression for growth in response to Suc accumulation under sink-limited conditions. To test this hypothesis, plants with genetically decreased T6P content and SnRK1 overexpression were transferred from cold to warm to analyze the role of T6P/SnRK1 in relief of growth restriction. Compared with the wild type, these plants were impaired in immediate growth recovery. It is concluded that the T6P/SnRK1 signaling pathway responds to Suc induced by sink restriction that enables growth recovery following relief of limitations such as low temperature. PMID:23735508

  12. Genetic Dissection of the Type VI Secretion System in Acinetobacter and Identification of a Novel Peptidoglycan Hydrolase, TagX, Required for Its Biogenesis

    PubMed Central

    Weber, Brent S.; Hennon, Seth W.; Wright, Meredith S.; Scott, Nichollas E.; de Berardinis, Véronique; Foster, Leonard J.; Ayala, Juan A.; Adams, Mark D.

    2016-01-01

    ABSTRACT The type VI secretion system (T6SS) is a widespread secretory apparatus produced by Gram-negative bacteria that has emerged as a potent mediator of antibacterial activity during interbacterial interactions. Most Acinetobacter species produce a genetically conserved T6SS, although the expression and functionality of this system vary among different strains. Some pathogenic Acinetobacter baumannii strains activate this secretion system via the spontaneous loss of a plasmid carrying T6SS repressors. In this work, we compared the expression of T6SS-related genes via transcriptome sequencing and differential proteomics in cells with and without the plasmid. This approach, together with the mutational analysis of the T6SS clusters, led to the determination of the genetic components required to elaborate a functional T6SS in the nosocomial pathogen A. baumannii and the nonpathogen A. baylyi. By constructing a comprehensive combination of mutants with changes in the T6SS-associated vgrG genes, we delineated their relative contributions to T6SS function. We further determined the importance of two effectors, including an effector-immunity pair, for antibacterial activity. Our genetic analysis led to the identification of an essential membrane-associated structural component named TagX, which we have characterized as a peptidoglycan hydrolase possessing l,d-endopeptidase activity. TagX shows homology to known bacteriophage l,d-endopeptidases and is conserved in the T6SS clusters of several bacterial species. We propose that TagX is the first identified enzyme that fulfills the important role of enabling the transit of T6SS machinery across the peptidoglycan layer of the T6SS-producing bacterium. PMID:27729508

  13. Type VI secretion system helps find a niche.

    PubMed

    Kapitein, Nicole; Mogk, Axel

    2014-07-09

    Type VI secretion systems (T6SSs) deliver toxins into target cells and thus play a role in bacterial warfare. In this issue of Cell Host & Microbe, Ma et al. (2014) demonstrate that T6SS-dependent attack during interbacterial competition in the host context enables niche colonization by Agrobacterium tumefaciens. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. 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.

  15. The type VI secretion system encoded in Salmonella pathogenicity island 19 is required for Salmonella enterica serotype Gallinarum survival within infected macrophages.

    PubMed

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

    2013-04-01

    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.

  16. Rational design of reversible inhibitors for trehalose 6-phosphate phosphatases.

    PubMed

    Liu, Chunliang; Dunaway-Mariano, Debra; Mariano, Patrick S

    2017-03-10

    In some organisms, environmental stress triggers trehalose biosynthesis that is catalyzed collectively by trehalose 6-phosphate synthase, and trehalose 6-phosphate phosphatase (T6PP). T6PP catalyzes the hydrolysis of trehalose 6-phosphate (T6P) to trehalose and inorganic phosphate and is a promising target for the development of antibacterial, antifungal and antihelminthic therapeutics. Herein, we report the design, synthesis and evaluation of a library of aryl d-glucopyranoside 6-sulfates to serve as prototypes for small molecule T6PP inhibitors. Steady-state kinetic techniques were used to measure inhibition constants (K i ) of a panel of structurally diverse T6PP orthologs derived from the pathogens Brugia malayi, Ascaris suum, Mycobacterium tuberculosis, Shigella boydii and Salmonella typhimurium. The binding affinities of the most active inhibitor of these T6PP orthologs, 4-n-octylphenyl α-d-glucopyranoside 6-sulfate (9a), were found to be in the low micromolar range. The K i of 9a with the B. malayi T6PP ortholog is 5.3 ± 0.6 μM, 70-fold smaller than the substrate Michaelis constant. The binding specificity of 9a was demonstrated using several representative sugar phosphate phosphatases from the HAD enzyme superfamily, the T6PP protein fold family of origin. Lastly, correlations drawn between T6PP active site structure, inhibitor structure and inhibitor binding affinity suggest that the aryl d-glucopyranoside 6-sulfate prototypes will find future applications as a platform for development of tailored second-generation T6PP inhibitors. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. 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.

  18. Identification, Structure, and Function of a Novel Type VI Secretion Peptidoglycan Glycoside Hydrolase Effector-Immunity Pair*

    PubMed Central

    Whitney, John C.; Chou, Seemay; Russell, Alistair B.; Biboy, Jacob; Gardiner, Taylor E.; Ferrin, Michael A.; Brittnacher, Mitchell; Vollmer, Waldemar; Mougous, Joseph D.

    2013-01-01

    Bacteria employ type VI secretion systems (T6SSs) to facilitate interactions with prokaryotic and eukaryotic cells. Despite the widespread identification of T6SSs among Gram-negative bacteria, the number of experimentally validated substrate effector proteins mediating these interactions remains small. Here, employing an informatics approach, we define novel families of T6S peptidoglycan glycoside hydrolase effectors. Consistent with the known intercellular self-intoxication exhibited by the T6S pathway, we observe that each effector gene is located adjacent to a hypothetical open reading frame encoding a putative periplasmically localized immunity determinant. To validate our sequence-based approach, we functionally investigate a representative family member from the soil-dwelling bacterium Pseudomonas protegens. We demonstrate that this protein is secreted in a T6SS-dependent manner and that it confers a fitness advantage in growth competition assays with Pseudomonas putida. In addition, we determined the 1.4 Å x-ray crystal structure of this effector in complex with its cognate immunity protein. The structure reveals the effector shares highest overall structural similarity to a glycoside hydrolase family associated with peptidoglycan N-acetylglucosaminidase activity, suggesting that T6S peptidoglycan glycoside hydrolase effector families may comprise significant enzymatic diversity. Our structural analyses also demonstrate that self-intoxication is prevented by the immunity protein through direct occlusion of the effector active site. This work significantly expands our current understanding of T6S effector diversity. PMID:23878199

  19. How do sugars regulate plant growth and development? New insight into the role of trehalose-6-phosphate.

    PubMed

    O'Hara, Liam E; Paul, Matthew J; Wingler, Astrid

    2013-03-01

    Plant growth and development are tightly controlled in response to environmental conditions that influence the availability of photosynthetic carbon in the form of sucrose. Trehalose-6-phosphate (T6P), the precursor of trehalose in the biosynthetic pathway, is an important signaling metabolite that is involved in the regulation of plant growth and development in response to carbon availability. In addition to the plant's own pathway for trehalose synthesis, formation of T6P or trehalose by pathogens can result in the reprogramming of plant metabolism and development. Developmental processes that are regulated by T6P range from embryo development to leaf senescence. Some of these processes are regulated in interaction with phytohormones, such as auxin. A key interacting factor of T6P signaling in response to the environment is the protein kinase sucrose non-fermenting related kinase-1 (SnRK1), whose catalytic activity is inhibited by T6P. SnRK1 is most likely involved in the adjustment of metabolism and growth in response to starvation. The transcription factor bZIP11 has recently been identified as a new player in the T6P/SnRK1 regulatory pathway. By inhibiting SnRK1, T6P promotes biosynthetic reactions. This regulation has important consequences for crop production, for example, in the developing wheat grain and during the growth of potato tubers.

  20. The Opportunistic Pathogen Serratia marcescens Utilizes Type VI Secretion To Target Bacterial Competitors ▿†

    PubMed Central

    Murdoch, Sarah L.; Trunk, Katharina; English, Grant; Fritsch, Maximilian J.; Pourkarimi, Ehsan; Coulthurst, Sarah J.

    2011-01-01

    The type VI secretion system (T6SS) is the most recently described and least understood of the protein secretion systems of Gram-negative bacteria. It is widely distributed and has been implicated in the virulence of various pathogens, but its mechanism and exact mode of action remain to be defined. Additionally there have been several very recent reports that some T6SSs can target bacteria rather than eukaryotic cells. Serratia marcescens is an opportunistic enteric pathogen, a class of bacteria responsible for a significant proportion of hospital-acquired infections. We describe the identification of a functional T6SS in S. marcescens strain Db10, the first report of type VI secretion by an opportunist enteric bacterium. The T6SS of S. marcescens Db10 is active, with secretion of Hcp to the culture medium readily detected, and is expressed constitutively under normal growth conditions from a large transcriptional unit. Expression of the T6SS genes did not appear to be dependent on the integrity of the T6SS. The S. marcescens Db10 T6SS is not required for virulence in three nonmammalian virulence models. It does, however, exhibit dramatic antibacterial killing activity against several other bacterial species and is required for S. marcescens to persist in a mixed culture with another opportunist pathogen, Enterobacter cloacae. Importantly, this antibacterial killing activity is highly strain specific, with the S. marcescens Db10 T6SS being highly effective against another strain of S. marcescens with a very similar and active T6SS. We conclude that type VI secretion plays a crucial role in the competitiveness, and thus indirectly the virulence, of S. marcescens and other opportunistic bacterial pathogens. PMID:21890705

  1. 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.

  2. Functional role of a conserved motif in TM6 of the rat mu opioid receptor: constitutively active and inactive receptors result from substitutions of Thr6.34(279) with Lys and Asp.

    PubMed

    Huang, P; Li, J; Chen, C; Visiers, I; Weinstein, H; Liu-Chen, L Y

    2001-11-13

    Mutations within the "X1BBX2X3B" motif or its variants in the junction of the third intracellular (i3) loop and the sixth transmembrane domain (TM6) have been shown to lead to constitutive activation of several G protein-coupled receptors (GPCRs). In this study, T6.34(279) at the X3 locus of the rat mu opioid receptor was mutated to Lys and Asp, and the mutants were examined for binding and signaling properties. The T6.34(279)K mutant was poorly expressed, and pretreatment with naloxone greatly enhanced its expression. This construct exhibited properties identified previously with constitutive activation: (1) compared with the wild type, it produced much higher agonist-independent [35S]GTPgammaS binding, which was abolished by pertussis toxin treatment; (2) it displayed an enhanced affinity for the agonist DAMGO similar to that of the high-affinity state of the wild type, which was not altered by GTPgammaS, while having unchanged affinity for the antagonist diprenorphine. The T6.34(279)K mutant displayed a higher intracellular receptor pool than the wild type. Naloxone inhibited the basal [35S]GTPgammaS binding of the T6.34(279)K mutant, demonstrating inverse agonist activity at this mutant receptor. In contrast, the T6.34(279)D substitution did not increase basal [35S]GTPgammaS binding, greatly reduced agonist-promoted [35S]GTPgammaS binding, and markedly decreased affinity for DAMGO. Thus, the T6.34(279)D mutant adopts conformations corresponding to inactive states of the receptor. The results were interpreted in the structural context of a model for the mu opioid receptor that incorporates the information from the crystal structure of rhodopsin. The interaction of T6.34(279) with R3.50(165) in the mu opioid receptor is considered to stabilize the inactive conformations. The T6.34(279)K substitution would then disrupt this interaction and support agonist-free activation, while T6.34(279)D mutation should strengthen this interaction which keeps the receptor in

  3. Conceptual Design and Analysis of Orbital Cryogenic Liquid Storage and Supply Systems.

    DTIC Science & Technology

    1981-05-01

    ngth and good weldability are of prime importance to a vessel designed for burst. The higher tensile strength of 2014-T6 or 2219 -T62, comparcd to...T6 or a 2219 -T62 alloy. Mart in :arietta has developed techniques for welding both alloys. Titan launch vehicle tanks are constructed of 2014-T6 and...the External Tank for the Shuttle Space Transportation System is made from 2219 -T62. However, neither of these alloys is as easy to weld as 6061

  4. 10 CFR 2.709 - Discovery against NRC staff.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... be produced for the in camera inspection of the presiding officer, exclusively, if requested by the... Administration, Security Processing Unit, Mail Stop T-6E46, U.S. Nuclear Regulatory Commission, Washington, DC...

  5. 10 CFR 2.709 - Discovery against NRC staff.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... covered by the application must be produced for the in camera inspection of the presiding officer... fingerprints to the NRC Office of Administration, Security Processing Unit, Mail Stop T-6E46, U.S. Nuclear...

  6. 10 CFR 2.709 - Discovery against NRC staff.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... covered by the application must be produced for the in camera inspection of the presiding officer... fingerprints to the NRC Office of Administration, Security Processing Unit, Mail Stop T-6E46, U.S. Nuclear...

  7. 14 CFR 91.1507 - Fuel tank system inspection program.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) Illyushin Aviation IL 96T (6) Bristol Aircraft Britannia 305 (7) Handley Page Herald Type 300 (8) Avions Marcel Dassault—Breguet Aviation Mercure 100C (9) Airbus Caravelle (10) Lockheed L-300 ...

  8. 14 CFR 121.1113 - Fuel tank system maintenance program.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Flugtechnische Werk VFW-614 (5) Illyushin Aviation IL 96T (6) Bristol Aircraft Britannia 305 (7) Handley Page Herald Type 300 (8) Avions Marcel Dassault—Breguet Aviation Mercure 100C (9) Airbus Caravelle (10...

  9. 14 CFR 129.113 - Fuel tank system maintenance program.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Flugtechnische Werk VFW-614 (5) Illyushin Aviation IL 96T (6) Bristol Aircraft Britannia 305 (7) Handley Page Herald Type 300 (8) Avions Marcel Dassault—Breguet Aviation Mercure 100C (9) Airbus Caravelle (10...

  10. Deadly syringes: type VI secretion system activities in pathogenicity and interbacterial competition.

    PubMed

    Kapitein, Nicole; Mogk, Axel

    2013-02-01

    Among specialized bacterial secretion systems, the most widespread is the type VI secretion system (T6SS). This transports effector molecules into target cells in a single, cell-contact dependent step. T6SSs are structurally related to the cell-puncturing device of tailed bacteriophages and predicted to function as contractile injection machineries that perforate eukaryotic and prokaryotic target membranes for effector delivery. Activities of T6SSs can play important roles in virulence by modifying the eukaryotic host cytoskeleton through actin crosslinking. They are also efficient weaponry in interbacterial warfare and provide a fitness advantage by hydrolyzing cell walls of opponent bacteria. The role of T6SSs in interbacterial competition might enable pathogens to outcompete commensal bacteria and facilitate host colonization. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Gage restraint measurement system comparison tests : railbound and hi-rail vehicles

    DOT National Transportation Integrated Search

    2003-12-01

    Comparative tests were conducted to evaluate the gage restraint measurement system (GRMS) testing capabilities of a railbound GRMS vehicle, Federal Railroad Administration's (FRA's) T-6, and a hi-rail vehicle, Holland Company's TrackStar GRMS system....

  12. Horizontal Gene Transfer of Functional Type VI Killing Genes by Natural Transformation.

    PubMed

    Thomas, Jacob; Watve, Samit S; Ratcliff, William C; Hammer, Brian K

    2017-07-25

    Horizontal gene transfer (HGT) can have profound effects on bacterial evolution by allowing individuals to rapidly acquire adaptive traits that shape their strategies for competition. One strategy for intermicrobial antagonism often used by Proteobacteria is the genetically encoded contact-dependent type VI secretion system (T6SS), a weapon used to kill heteroclonal neighbors by direct injection of toxic effectors. Here, we experimentally demonstrate that Vibrio cholerae can acquire new T6SS effector genes via horizontal transfer and utilize them to kill neighboring cells. Replacement of one or more parental alleles with novel effectors allows the recombinant strain to dramatically outcompete its parent. Using spatially explicit modeling, we examine how this process could affect the ecology and evolution of surface-attached microbial populations. HGT of T6SS effector-immunity pairs is risky: transformation brings a cell into conflict with its former clone mates but can be adaptive when superior T6SS alleles are acquired. More generally, we find that these costs and benefits are not symmetric and that high rates of HGT can act as a hedge against competitors with unpredictable T6SS efficacy. We conclude that antagonism and horizontal transfer drive successive rounds of weapon optimization and selective sweeps, dynamically shaping the composition of microbial communities. IMPORTANCE The contact-dependent type VI secretion system (T6SS) is frequently used by Proteobacteria to kill adjacent competitors. While DNA released by T6 killing can be horizontally acquired, it remains untested whether T6 genes themselves can be horizontally acquired and then utilized to compete with neighboring cells. Using naturally transformable Vibrio cholerae , we provide the first direct empirical support for the hypothesis that T6 genes are exchanged horizontally (e.g., from dead competitors) and functionally deployed to compete with neighboring cells. Using computational simulations, we

  13. Proteomic Identification of Novel Secreted Antibacterial Toxins of the Serratia marcescens Type VI Secretion System*

    PubMed Central

    Fritsch, Maximilian J.; Trunk, Katharina; Diniz, Juliana Alcoforado; Guo, Manman; Trost, Matthias; Coulthurst, Sarah J.

    2013-01-01

    It has recently become apparent that the Type VI secretion system (T6SS) is a complex macromolecular machine used by many bacterial species to inject effector proteins into eukaryotic or bacterial cells, with significant implications for virulence and interbacterial competition. “Antibacterial” T6SSs, such as the one elaborated by the opportunistic human pathogen, Serratia marcescens, confer on the secreting bacterium the ability to rapidly and efficiently kill rival bacteria. Identification of secreted substrates of the T6SS is critical to understanding its role and ability to kill other cells, but only a limited number of effectors have been reported so far. Here we report the successful use of label-free quantitative mass spectrometry to identify at least eleven substrates of the S. marcescens T6SS, including four novel effector proteins which are distinct from other T6SS-secreted proteins reported to date. These new effectors were confirmed as antibacterial toxins and self-protecting immunity proteins able to neutralize their cognate toxins were identified. The global secretomic study also unexpectedly revealed that protein phosphorylation-based post-translational regulation of the S. marcescens T6SS differs from that of the paradigm, H1-T6SS of Pseudomonas aeruginosa. Combined phosphoproteomic and genetic analyses demonstrated that conserved PpkA-dependent threonine phosphorylation of the T6SS structural component Fha is required for T6SS activation in S. marcescens and that the phosphatase PppA can reverse this modification. However, the signal and mechanism of PpkA activation is distinct from that observed previously and does not appear to require cell–cell contact. Hence this study has not only demonstrated that new and species-specific portfolios of antibacterial effectors are secreted by the T6SS, but also shown for the first time that PpkA-dependent post-translational regulation of the T6SS is tailored to fit the needs of different bacterial

  14. 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

  15. Frontiers in Anisotropic Shock-Wave Modeling

    DTIC Science & Technology

    2012-02-01

    stress ( PMMA ) waves for plate impact tests (im- pact velocities 450 and 895 m/s) - target AA7010 T6...simulation of stress ( PMMA ) waves for plate impact tests (impact velocities 450 and 895 m/s) - target AA7010 T6...impacts a target plate, which is bonded to a polymethylmethacrylate ( PMMA ) plate. In this report, the case is considered where the diameters of the flyer

  16. Type VI Secretion is a Major Virulence Determinant in Burkholderia Mallei

    DTIC Science & Technology

    2007-06-01

    PAGE unclassified Proteobacteria have evolved at least five distinct secre- tion pathways, types I– V , to transport proteins from the cytoplasm to the...coli (Aec), V . cholerae (Vas), Edwardsiella tarda (Evp), Salmonella enterica (Sci) and Rhizobium legumi- nosarum (Imp). 1468 M. A. Schell et al...encoded in the B. mallei T6S gene cluster (Fig. 2) that was similar to Hcp-family proteins that are secreted by T6SSs in V . cholerae, P. aeruginosa

  17. Atomatic X-Ray Diffraction Machine Measurement of Residual Stress in Aluminum Alloys

    DTIC Science & Technology

    1975-12-01

    instability. Data ,ecordinc Stress measurements were recorded on the integral chart j recorder. Scale factors were modified to provide an ex- panded... scale to facilitate data analysis. A scale of 10,000 psi per inch and a chart speed of 15 inches per hour was used for all stress wea.aurements. The...accomplished. on the 7178-T6 specimen. This indicated less stable operation than the measrement of the 2024-T6 specimen but provided useable results (Fig

  18. 27 CFR 9.66 - Russian River Valley.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Road, section 12, T6N, R10W, on the Valley Ford map). (9) Proceed 0.9 mile northeast on Bodega Road to... south, (known locally as Barnett Valley Road, T6N, R9W, on the Camp Meeker map). (10) Proceed 2.2 miles south, and then east, on Barnett Valley Road, crossing over the Valley Ford map, to its intersection...

  19. 27 CFR 9.66 - Russian River Valley.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Road, section 12, T6N, R10W, on the Valley Ford map). (9) Proceed 0.9 mile northeast on Bodega Road to... south, (known locally as Barnett Valley Road, T6N, R9W, on the Camp Meeker map). (10) Proceed 2.2 miles south, and then east, on Barnett Valley Road, crossing over the Valley Ford map, to its intersection...

  20. 27 CFR 9.66 - Russian River Valley.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Road, section 12, T6N, R10W, on the Valley Ford map). (9) Proceed 0.9 mile northeast on Bodega Road to... south, (known locally as Barnett Valley Road, T6N, R9W, on the Camp Meeker map). (10) Proceed 2.2 miles south, and then east, on Barnett Valley Road, crossing over the Valley Ford map, to its intersection...

  1. Report on Sediment Transport Events on Shelf and Slope (STRESS) Field Season 1: Winter 1988-1989 Benthic Acoustic Stress Sensor (BASS) Component

    DTIC Science & Technology

    1989-12-01

    Analog measurements T7- - T8- - TR1- TR2- PTCH ROLL 0 minutes / 30 minutes TI-- T2-- T3-- T4-- T5--T6-- T7- - T8- - TR1- TR2- PTCH ROLL 10 minutes...40 minutes TI-- T2-- T3-- T4-- T--T6-- T7- - T8- - TRI- TR2- PTCH ROLL 20 minutes / 50 minutes 11 Table 4: BASS Tattletale Spectra Record Data Format

  2. Cardiovascular autonomic control in paraplegic and quadriplegic.

    PubMed

    de Carvalho Abreu, Elizângela Márcia; Dias, Lucas Pinto Salles; Lima, Fernanda Pupio Silva; de Paula Júnior, Alderico Rodrigues; Lima, Mário Oliveira

    2016-04-01

    Spinal cord injury (SCI) is commonly associated with devastating paralysis. This condition also results in cardiovascular autonomic dysfunction associated with increased mortality from cardiovascular disease. The purpose of this study was to explore the differences in cardiovascular autonomic modulation in individuals with and without SCI. The study included 60 individuals: 30 individuals without SCI, who formed the control group-CG and 30 individuals with SCI, who formed the SCI group-SCIG. The latter group was divided into two, one group of subjects with SCI above the spinal segment T6-SCIG (above T6) and a group of individuals with SCI below T6-SCIG (below T6). The subjects were evaluated by linear and nonlinear analysis of heart rate variability (HRV). The SCIG showed significantly lower square root of the mean squares differences of successive NN intervals (rMSSD), number of pairs of adjacent NN intervals differing by more than 50 ms (pNN50), standard deviation of short-term HRV (SD1), and high frequency power (HF). Their low frequency power (LF) in absolute units (ms(2)) was significantly lower and their normalized units (n.u.) were significantly higher. Their LF/HF ratio was significantly higher, and sample entropy (SampEn), which indicates the complexity and irregularity of the NN intervals time series, was significantly lower compared to the CG. The differences between the SCIG and CG were derived mainly from the SCIG (above T6). The correlation test revealed very low values between each of the parameters evaluated for CG and SCIG. The SCIG (above T6) showed greater cardiovascular autonomic impairment compared to SCIG (below T6) and CG. The SCIG (below T6) also presented some degree of autonomic dysfunction. All parameters, linear or nonlinear, are suitable to demonstrate the differences between the SCIG and CG.

  3. 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

  4. Proceedings of the Army Symposium on Solid Mechanics, 1982 - Critical Mechanics Problems in Systems Design, 21-23 September 1982, Bass River, Cape Cod, Massachusetts

    DTIC Science & Technology

    1982-09-01

    graphite , Kevlar and S- glass /epoxy composites in four different structural panel configurations. A hardened 6061-T6 aluminum sandwich...SELECTION Shelter wall panels constructed from graphite , Kevlar and S- glass /epoxy composite materials along with 6061-T6 aluminum were 258 considered...some recent test results from Kevlar Graphite and Glass composites in addition to ceramic materials an occasikal bimodality has existed. In most

  5. A Transcriptional Regulatory Mechanism Finely Tunes the Firing of Type VI Secretion System in Response to Bacterial Enemies

    PubMed Central

    Lazzaro, Martina; Feldman, Mario F.

    2017-01-01

    ABSTRACT The ability to detect and measure danger from an environmental signal is paramount for bacteria to respond accordingly, deploying strategies that halt or counteract potential cellular injury and maximize survival chances. Type VI secretion systems (T6SSs) are complex bacterial contractile nanomachines able to target toxic effectors into neighboring bacteria competing for the same colonization niche. Previous studies support the concept that either T6SSs are constitutively active or they fire effectors in response to various stimuli, such as high bacterial density, cell-cell contact, nutrient depletion, or components from dead sibling cells. For Serratia marcescens, it has been proposed that its T6SS is stochastically expressed, with no distinction between harmless or aggressive competitors. In contrast, we demonstrate that the Rcs regulatory system is responsible for finely tuning Serratia T6SS expression levels, behaving as a transcriptional rheostat. When confronted with harmless bacteria, basal T6SS expression levels suffice for Serratia to eliminate the competitor. A moderate T6SS upregulation is triggered when, according to the aggressor-prey ratio, an unbalanced interplay between homologous and heterologous effectors and immunity proteins takes place. Higher T6SS expression levels are achieved when Serratia is challenged by a contender like Acinetobacter, which indiscriminately fires heterologous effectors able to exert lethal cellular harm, threatening the survival of the Serratia population. We also demonstrate that Serratia’s RcsB-dependent T6SS regulatory mechanism responds not to general stress signals but to the action of specific effectors from competitors, displaying an exquisite strategy to weigh risks and keep the balance between energy expenditure and fitness costs. PMID:28830939

  6. The type VI secretion system impacts bacterial invasion and population dynamics in a model intestinal microbiota

    NASA Astrophysics Data System (ADS)

    Logan, Savannah L.; Shields, Drew S.; Hammer, Brian K.; Xavier, Joao B.; Parthasarathy, Raghuveer

    Animal gastrointestinal tracts are home to a diverse community of microbes. The mechanisms by which microbial species interact and compete in this dense, physically dynamic space are poorly understood, limiting our understanding of how natural communities are assembled and how different communities could be engineered. Here, we focus on a physical mechanism for competition: the type VI secretion system (T6SS). The T6SS is a syringe-like organelle used by certain bacteria to translocate effector proteins across the cell membranes of target bacterial cells, killing them. Here, we use T6SS+ and T6SS- strains of V. cholerae, the pathogen that causes cholera in humans, and light sheet fluorescence microscopy for in vivo imaging to show that the T6SS provides an advantage to strains colonizing the larval zebrafish gut. Furthermore, we show that T6SS+ bacteria can invade and alter an existing population of a different species in the zebrafish gut, reducing its abundance and changing the form of its population dynamics. This work both demonstrates a mechanism for altering the gut microbiota with an invasive species and explores the processes controlling the stability and dynamics of the gut ecosystem. Research Corporation, Gordon and Betty Moore Foundation, and the Simons Foundation.

  7. A Type VI Secretion System Encoding Locus Is Required for Bordetella bronchiseptica Immunomodulation and Persistence In Vivo

    PubMed Central

    Muse, Sarah J.; Park, Jihye; Spidale, Nicholas; Kennett, Mary J.; Hester, Sara E.; Chen, Chun; Dudley, Edward G.; Harvill, Eric T.

    2012-01-01

    Type VI Secretion Systems (T6SSs) have been identified in numerous Gram-negative pathogens, but the lack of a natural host infection model has limited analysis of T6SS contributions to infection and pathogenesis. Here, we describe disruption of a gene within locus encoding a putative T6SS in Bordetella bronchiseptica strain RB50, a respiratory pathogen that circulates in a broad range of mammals, including humans, domestic animals, and mice. The 26 gene locus encoding the B. bronchiseptica T6SS contains apparent orthologs to all known core genes and possesses thirteen novel genes. By generating an in frame deletion of clpV, which encodes a putative ATPase required for some T6SS-dependent protein secretion, we observe that ClpV contributes to in vitro macrophage cytotoxicity while inducing several eukaryotic proteins associated with apoptosis. Additionally, ClpV is required for induction of IL-1β, IL-6, IL-17, and IL-10 production in J774 macrophages infected with RB50. During infections in wild type mice, we determined that ClpV contributes to altered cytokine production, increased pathology, delayed lower respiratory tract clearance, and long term nasal cavity persistence. Together, these results reveal a natural host infection system in which to interrogate T6SS contributions to immunomodulation and pathogenesis. PMID:23071529

  8. 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. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  9. 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

  10. Atomic Structure of Type VI Contractile Sheath from Pseudomonas aeruginosa.

    PubMed

    Salih, Osman; He, Shaoda; Planamente, Sara; Stach, Lasse; MacDonald, James T; Manoli, Eleni; Scheres, Sjors H W; Filloux, Alain; Freemont, Paul S

    2017-12-21

    Pseudomonas aeruginosa has three type VI secretion systems (T6SSs), H1-, H2-, and H3-T6SS, each belonging to a distinct group. The two T6SS components, TssB/VipA and TssC/VipB, assemble to form tubules that conserve structural/functional homology with tail sheaths of contractile bacteriophages and pyocins. Here, we used cryoelectron microscopy to solve the structure of the H1-T6SS P. aeruginosa TssB1C1 sheath at 3.3 Å resolution. Our structure allowed us to resolve some features of the T6SS sheath that were not resolved in the Vibrio cholerae VipAB and Francisella tularensis IglAB structures. Comparison with sheath structures from other contractile machines, including T4 phage and R-type pyocins, provides a better understanding of how these systems have conserved similar functions/mechanisms despite evolution. We used the P. aeruginosa R2 pyocin as a structural template to build an atomic model of the TssB1C1 sheath in its extended conformation, allowing us to propose a coiled-spring-like mechanism for T6SS sheath contraction. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  11. The Role of Type VI Secretion System Effectors in Target Cell Lysis and Subsequent Horizontal Gene Transfer.

    PubMed

    Ringel, Peter David; Hu, Di; Basler, Marek

    2017-12-26

    Bacteria use type VI secretion systems (T6SSs) to manipulate host cells during pathogenesis or to kill competing bacteria, which, in some cases, increases horizontal gene transfer. These functions largely depend on T6SS regulation, dynamics, and the set of effectors that the system delivers into the target cells. Here, we show that Acinetobacter baylyi ADP1 assembles a highly dynamic T6SS capable of killing and lysing bacterial cells. T6SS function depends on conserved T6SS components as well as Acinetobacter-specific genes of unknown function. Five different effectors, encoded next to VgrG or PAAR proteins and their cognate immunity proteins, cause distinct changes in the prey cells, resulting in various degrees of their lysis. Prey lysis correlates with the rate of DNA transfer from prey to predator, suggesting that lytic effectors are required for efficient T6SS-dependent horizontal gene transfer in naturally competent bacteria. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  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. Acinetobacter baumannii Utilizes a Type VI Secretion System for Bacterial Competition

    PubMed Central

    Carruthers, Michael D.; Nicholson, Paul A.; Tracy, Erin N.; Munson, Robert S.

    2013-01-01

    Type VI secretion systems (T6SS) are a class of macromolecular secretion machines that are utilized by a number of bacteria for inter-bacterial competition or to elicit responses in eukaryotic cells. Acinetobacter baumannii is an opportunistic pathogen that causes severe infections in humans. These infections, including pneumonia and bacteremia, are important, as they are often associated with hospitals and medical-settings where they disproportionally affect critically ill patients like those residing in intensive care units. While it is known that A. baumannii genomes carry genes whose predicted products have homology with T6SS-associated gene products from other bacteria, and secretion of a major T6SS structural protein Hcp has been demonstrated, no additional work on an A. baumannii T6SS has been reported. Herein, we demonstrated that A. baumannii strain M2 secretes Hcp and this secretion was dependent upon TssB, an ortholog of a bacteriophage contractile sheath protein, confirming that strain M2 produces a functional T6SS. Additionally, we demonstrated that the ability of strain M2 to out-compete Escherichia coli was reliant upon the products of tssB and hcp. Collectively, our data have provided the first evidence demonstrating function in inter-bacterial competition, for a T6SS produced by A. baumannii. PMID:23527179

  14. Quantitative single-cell characterization of bacterial interactions reveals type VI secretion is a double-edged sword

    PubMed Central

    LeRoux, Michele; De Leon, Justin A.; Kuwada, Nathan J.; Russell, Alistair B.; Pinto-Santini, Delia; Hood, Rachel D.; Agnello, Danielle M.; Robertson, Stephen M.; Wiggins, Paul A.; Mougous, Joseph D.

    2012-01-01

    Interbacterial interaction pathways play an important role in defining the structure and complexity of bacterial associations. A quantitative description of such pathways offers promise for understanding the forces that contribute to community composition. We developed time-lapse fluorescence microscopy methods for quantitation of interbacterial interactions and applied these to the characterization of type VI secretion (T6S) in Pseudomonas aeruginosa. Our analyses allowed a direct determination of the efficiency of recipient cell lysis catalyzed by this intercellular toxin delivery pathway and provided evidence that its arsenal extends beyond known effector proteins. Measurement of T6S apparatus localization revealed correlated activation among neighboring cells, which, taken together with genetic data, implicate the elaboration of a functional T6S apparatus with a marked increase in susceptibility to intoxication. This possibility was supported by the identification of T6S-inactivating mutations in a genome-wide screen for resistance to T6S-mediated intoxication and by time-lapse fluorescence microscopy analyses showing a decreased lysis rate of recipient cells lacking T6S function. Our discoveries highlight the utility of single-cell approaches for measuring interbacterial phenomena and provide a foundation for studying the contribution of a widespread bacterial interaction pathway to community structure. PMID:23150540

  15. Satellite tobacco mosaic virus sequence variants with only five Nucleotide differences can interfere with each other in a cross protection-like phenomenon in plants

    USGS Publications Warehouse

    Kurath, Gael; Dodds, J. Allan

    1994-01-01

    The type strain of satellite tobacco mosaic virus (STMV) contains two major variants, designated type 5 (T5) and type 6 (T6), which can be easily distinguished by RNase protection analyses. Clones containing cDNA of representative T5 and T6 STMV genomes have only five single-base differences in the entire 1059-nucleotide genome, and RNA transcribed from each clone is highly infectious when inoculated onto tobacco plants. The different RNase protection assay patterns can be used as genetic markers to identify individual STMV variants and to follow the interactions of variants and their progeny during coinfections in plants. The study described here investigated the effects of coinoculation and various delayed inoculations of T5 and T6 variants on the composition of the progeny STMV populations in systemically infected tobacco tissues. When T5 and T6 STMV RNAs were coinoculated or inoculated with 1-hr delays, the progeny from individual plants most often contained a mixture of T5 and T6 genomes. However, when there was a 24-hr delay between inoculations, the balance of T5 and T6 components in the progeny populations shifted toward predominance of the first variant inoculated. With delays of 3 or 7 days only the first variant was evident in the progeny populations, indicating that established replication of one STMV variant interferes with replication of another in a manner similar to the cross protection phenomenon.

  16. Structure-function analysis of HsiF, a gp25-like component of the type VI secretion system, in Pseudomonas aeruginosa.

    PubMed

    Lossi, Nadine S; Dajani, Rana; Freemont, Paul; Filloux, Alain

    2011-12-01

    Bacterial pathogens use a range of protein secretion systems to colonize their host. One recent addition to this arsenal is the type VI secretion system (T6SS), which is found in many Gram-negative bacteria. The T6SS involves 12-15 components, including a ClpV-like AAA(+) ATPase. Moreover, the VgrG and Hcp components have been proposed to form a puncturing device, based on structural similarity to the tail spike components gp5/gp27 and the tail tube component gp19 of the T4 bacteriophage, respectively. Another T6SS component shows similarity to a T4 phage protein, namely gp25. The gp25 protein has been proposed to have lysozyme activity. Other T6SS components do not exhibit obvious similarity to characterized T4 phage components. The genome of Pseudomonas aeruginosa contains three T6SS gene clusters. In each cluster a gene encoding a putative member of the gp25-like protein family was identified, which we called HsiF. We confirmed this similarity by analysing the structure of the P. aeruginosa HsiF proteins using secondary and tertiary structure prediction tools. We demonstrated that HsiF1 is crucial for the T6SS-dependent secretion of Hcp and VgrG. Importantly, lysozyme activity of HsiF proteins was not detectable, and we related this observation to the demonstration that HsiF1 localizes to the cytoplasm of P. aeruginosa. Finally, our data showed that a conserved glutamate, predicted to be required for proper HsiF folding, is essential for its function. In conclusion, our data confirm the central role of HsiF in the T6SS mechanism, provide information on the predicted HsiF structure, and call for reconsideration of the function of gp25-like proteins.

  17. Structure–function analysis of HsiF, a gp25-like component of the type VI secretion system, in Pseudomonas aeruginosa

    PubMed Central

    Lossi, Nadine S.; Dajani, Rana; Freemont, Paul

    2011-01-01

    Bacterial pathogens use a range of protein secretion systems to colonize their host. One recent addition to this arsenal is the type VI secretion system (T6SS), which is found in many Gram-negative bacteria. The T6SS involves 12–15 components, including a ClpV-like AAA+ ATPase. Moreover, the VgrG and Hcp components have been proposed to form a puncturing device, based on structural similarity to the tail spike components gp5/gp27 and the tail tube component gp19 of the T4 bacteriophage, respectively. Another T6SS component shows similarity to a T4 phage protein, namely gp25. The gp25 protein has been proposed to have lysozyme activity. Other T6SS components do not exhibit obvious similarity to characterized T4 phage components. The genome of Pseudomonas aeruginosa contains three T6SS gene clusters. In each cluster a gene encoding a putative member of the gp25-like protein family was identified, which we called HsiF. We confirmed this similarity by analysing the structure of the P. aeruginosa HsiF proteins using secondary and tertiary structure prediction tools. We demonstrated that HsiF1 is crucial for the T6SS-dependent secretion of Hcp and VgrG. Importantly, lysozyme activity of HsiF proteins was not detectable, and we related this observation to the demonstration that HsiF1 localizes to the cytoplasm of P. aeruginosa. Finally, our data showed that a conserved glutamate, predicted to be required for proper HsiF folding, is essential for its function. In conclusion, our data confirm the central role of HsiF in the T6SS mechanism, provide information on the predicted HsiF structure, and call for reconsideration of the function of gp25-like proteins. PMID:21873404

  18. Adenine Induces Differentiation of Rat Hepatic Stellate Cells

    PubMed Central

    Watanabe, Azuma; Sohail, Muhammad Adnan; Gautam, Samir; Gomes, Dawidson Assis

    2013-01-01

    Background and Aims Adenine is a uric acid pathway metabolite of no known function, and has recently been identified as a ligand for a rat G protein-coupled receptor. Due to the known role of other uric acid pathway metabolites in HSC biology, we tested the ability of adenine to induce HSC differentiation. Methods RT-PCR was performed for adenine receptor expression in T-6 and primary rat HSC. T-6 and primary rats HSC were cultured with and without adenine, and stellation examined. Next, we examined inhibition of calcium signaling using caged IP3. To test if adenine inhibits HSC chemotaxis T-6 cells and rat HSCs were cultured with or without adenine for 24 h in a transwell assay with PDGF as the chemoattractant. cDNA was prepared from T-6 and primary HSC for quantification of collagen 1 mRNA using real-time PCR. Results We found that mRNA for the adenine receptor is expressed in T-6 cells and primary rat HSC. Also, adenine induces HSC stellation and adenine inhibits IP3 mediated increase in cytosolic [Ca2+]i and inhibits chemotaxis in T-6 cells and primary rat HSC. Adenine was also shown to up-regulate α-SMA and collagen 1, and this effect is lost by using specific si-RNA for the adenine receptor. Finally, adenine inhibits endothelin-1-induced gel contraction. Conclusions The adenine receptor is present in T-6 cells and primary rats HSC. Adenine, via the adenine receptor, induces morphological change, and cytosolic calcium signaling, inhibits chemotaxis, and up-regulates collagen 1 mRNA in HSCs. PMID:22573344

  19. 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. Copyright © 2011 Wiley Periodicals, Inc.

  20. Isolation and characterization of T-even ghost-tolerant mutants of Escherichia coli.

    PubMed

    Nishikawa, Y; Maruo, B

    1976-07-01

    Mutants of Escherichia coli tolerant to the ghosts of T-even phages (T2, T4, and T6) have been isolated from a strain supersensitive to T6 phage. First, T6 supersensitive mutants were isolated from mutagenized E. coli W2252 by replica plating to T6 phage-overlaid agar. One of them, strain NM101, was mutagenized again, grown, and then plated with a high multiplicity of T4 and T6 ghosts. Surviving cells were checked for tolerance to ghosts and adsorption of phages. One such ghost-tolerant mutant, strain GT29, was tolerant to ghosts of both T4 and T6 phages and sensitive to T2 ghosts. This mutant was also sensitive to ethylenediaminetetraacetic acid and penicillin G and intermediately sensitive to acriflavine, sodium dodecyl sulfate, sodium deoxycholate, actinomycin D, and lysozyme. Another mutant, strain GT62, was tolerant not only to T4 and T6 ghosts but also to T2 ghosts. It was sensitive to sodium dodecyl sulfate, sodium deoxycholate, penicillin G, acridine orange, actinomycin D, phenethyl alcohol, and novobiocin and intermediately sensitive to acriflavine and lysozyme. Spontaneous revertants of strain GT62 were isolated with a frequency of 2.7 X 10(-9). It is suggested that ghosts attack host bacteria indirectly through the cell surface by a mechanism similar to the transmission hypothesis that was originally adopted by Nomura (1967) to explain the mechanism of the action of colicins, and that our ghost-tolerant mutants presumably have defects in the cell surface.

  1. Role of the Genes of Type VI Secretion System in Virulence of Rice Bacterial Brown Stripe Pathogen Acidovorax avenae subsp. avenae Strain RS-2

    PubMed Central

    Masum, Md. Mahidul Islam; Yang, Yingzi; Li, Bin; Olaitan, Ogunyemi Solabomi; Chen, Jie; Zhang, Yang; Fang, Yushi; Qiu, Wen; Wang, Yanli; Sun, Guochang

    2017-01-01

    The Type VI secretion system (T6SS) is a class of macromolecular machine that is required for the virulence of gram-negative bacteria. However, it is still not clear what the role of T6SS in the virulence of rice bacterial brown stripe pathogen Acidovorax avenae subsp. avenae (Aaa) is. The aim of the current study was to investigate the contribution of T6SS in Aaa strain RS2 virulence using insertional deletion mutation and complementation approaches. This strain produced weak virulence but contains a complete T6SS gene cluster based on a genome-wide analysis. Here we compared the virulence-related phenotypes between the wild-type (RS-2) and 25 T6SS mutants, which were constructed using homologous recombination methods. The mutation of 15 T6SS genes significantly reduced bacterial virulence and the secretion of Hcp protein. Additionally, the complemented 7 mutations ΔpppA, ΔclpB, Δhcp, ΔdotU, ΔicmF, ΔimpJ, and ΔimpM caused similar virulence characteristics as RS-2. Moreover, the mutant ΔpppA, ΔclpB, ΔicmF, ΔimpJ and ΔimpM genes caused by a 38.3~56.4% reduction in biofilm formation while the mutants ΔpppA, ΔclpB, ΔicmF and Δhcp resulted in a 37.5~44.6% reduction in motility. All together, these results demonstrate that T6SS play vital roles in the virulence of strain RS-2, which may be partially attributed to the reductions in Hcp secretion, biofilm formation and motility. However, differences in virulence between strain RS-1 and RS-2 suggest that other factors may also be involved in the virulence of Aaa. PMID:28934168

  2. Regulation of growth by the trehalose pathway

    PubMed Central

    Nunes, Cátia; Schluepmann, Henriette; Delatte, Thierry L; Wingler, Astrid; Silva, Anabela B; Fevereiro, Pedro S; Jansen, Marcus; Fiorani, Fabio; Wiese-Klinkenberg, Anika; Paul, Matthew J

    2013-01-01

    Carbon signaling can override carbon supply in the regulation of growth. At least some of this regulation is imparted by the sugar signal trehalose 6-phosphate (T6P) through the protein kinase, SnRK1. This signaling pathway regulates biosynthetic processes involved in growth under optimal growing conditions. Recently, using a seedling system we showed that under sub-optimal conditions, such as cold, carbon signaling by T6P/ SnRK1 enables recovery of growth following relief of the stress. The T6P/ SnRK1 mechanism thus could be selected as a means of improving low temperature tolerance. High-throughput automated Fv/Fm measurements provide a potential means to screen for T6P/ SnRK1, and here we confirm through measurements of Fv/Fm in rosettes that T6P promotes low temperature tolerance and recovery during cold to warm transfer. Further, to better understand the coordination between sugars, trehalose pathway, and temperature-dependent growth, we examine the interrelationship between sugars, trehalose phosphate synthase (TPS), and trehalose phosphate phosphatase (TPP) gene expression and T6P content in seedlings. Sucrose, particularly when fed exogenously, correlated well with TPS1 and TPPB gene expression, suggesting that these enzymes are involved in maintaining carbon flux through the pathway in relation to sucrose supply. However, when sucrose accumulated to higher levels under low temperature and low N, TPS1 and TPPB expression were less directly related to sucrose; other factors may also contribute to regulation of TPS1 and TPPB expression under these conditions. TPPA expression was not related to sucrose content and all genes were not well correlated with endogenous glucose. Our work has implications for understanding acclimation to sink-limited growth conditions such as low temperature and for screening cold-tolerant genotypes with altered T6P/ SnRK1 signaling. PMID:24084646

  3. Trehalose-6-Phosphate-Mediated Toxicity Determines Essentiality of OtsB2 in Mycobacterium tuberculosis In Vitro and in Mice

    PubMed Central

    Koliwer-Brandl, Hendrik; Hartman, Travis; Jacobs, William R.; Ioerger, Thomas R.; Ehrt, Sabine

    2016-01-01

    Trehalose biosynthesis is considered an attractive target for the development of antimicrobials against fungal, helminthic and bacterial pathogens including Mycobacterium tuberculosis. The most common biosynthetic route involves trehalose-6-phosphate (T6P) synthase OtsA and T6P phosphatase OtsB that generate trehalose from ADP/UDP-glucose and glucose-6-phosphate. In order to assess the drug target potential of T6P phosphatase, we generated a conditional mutant of M. tuberculosis allowing the regulated gene silencing of the T6P phosphatase gene otsB2. We found that otsB2 is essential for growth of M. tuberculosis in vitro as well as for the acute infection phase in mice following aerosol infection. By contrast, otsB2 is not essential for the chronic infection phase in mice, highlighting the substantial remodelling of trehalose metabolism during infection by M. tuberculosis. Blocking OtsB2 resulted in the accumulation of its substrate T6P, which appears to be toxic, leading to the self-poisoning of cells. Accordingly, blocking T6P production in a ΔotsA mutant abrogated otsB2 essentiality. T6P accumulation elicited a global upregulation of more than 800 genes, which might result from an increase in RNA stability implied by the enhanced neutralization of toxins exhibiting ribonuclease activity. Surprisingly, overlap with the stress response caused by the accumulation of another toxic sugar phosphate molecule, maltose-1-phosphate, was minimal. A genome-wide screen for synthetic lethal interactions with otsA identified numerous genes, revealing additional potential drug targets synergistic with OtsB2 suitable for combination therapies that would minimize the emergence of resistance to OtsB2 inhibitors. PMID:27936238

  4. Metabolism control over growth: a case for trehalose-6-phosphate in plants.

    PubMed

    Schluepmann, Henriette; Berke, Lidija; Sanchez-Perez, Gabino F

    2012-05-01

    How plants relate their requirements for energy with the reducing power necessary to fuel growth is not understood. The activated glucose forms and NADPH are key precursors in pathways yielding, respectively, energy and reducing power for anabolic metabolism. Moreover, they are substrates or allosteric regulators of trehalose-phosphate synthase (TPS1) in fungi and probably also in plants. TPS1 synthesizes the signalling metabolite trehalose-6-phosphate (T6P) and, therefore, has the potential to relate reducing power with energy metabolism to fuel growth. A working model is discussed where trehalose-6-phosphate (T6P) inhibition of SnRK1 is part of a growth-regulating loop in young and metabolically active heterotrophic plant tissues. SnRK1 is the Snf1 Related Kinase 1 and the plant homologue of the AMP-dependent protein kinase of animals, a central energy gauge. T6P accumulation in response to high sucrose levels in a cell inhibits SnRK1 activity, thus promoting anabolic processes and growth. When T6P levels drop due to low glucose-6-phosphate, uridine-diphosphoglucose, and altered NADPH or due to restricted TPS1 activity, active SnRK1 promotes catabolic processes required to respond to energy and carbon deprivation. The model explains why too little or too much T6P has been found to be growth inhibitory: Arabidopsis thaliana embryos and seedlings without TPS1 are growth arrested and Arabidopsis seedlings accumulating T6P on a trehalose medium are growth arrested. Finally, the insight gained with respect to the possible role of T6P metabolism, where it is known to alter developmental and environmental responses of plants, is discussed.

  5. Type VI Secretion System in Pseudomonas aeruginosa

    PubMed Central

    Hachani, Abderrahman; Lossi, Nadine S.; Hamilton, Alexander; Jones, Cerith; Bleves, Sophie; Albesa-Jové, David; Filloux, Alain

    2011-01-01

    Pseudomonas aeruginosa is a Gram-negative bacterium causing chronic infections in cystic fibrosis patients. Such infections are associated with an active type VI secretion system (T6SS), which consists of about 15 conserved components, including the AAA+ ATPase, ClpV. The T6SS secretes two categories of proteins, VgrG and Hcp. Hcp is structurally similar to a phage tail tube component, whereas VgrG proteins show similarity to the puncturing device at the tip of the phage tube. In P. aeruginosa, three T6SSs are known. The expression of H1-T6SS genes is controlled by the RetS sensor. Here, 10 vgrG genes were identified in the PAO1 genome, among which three are co-regulated with H1-T6SS, namely vgrG1a/b/c. Whereas VgrG1a and VgrG1c were secreted in a ClpV1-dependent manner, secretion of VgrG1b was ClpV1-independent. We show that VgrG1a and VgrG1c form multimers, which confirmed the VgrG model predicting trimers similar to the tail spike. We demonstrate that Hcp1 secretion requires either VgrG1a or VgrG1c, which may act independently to puncture the bacterial envelope and give Hcp1 access to the surface. VgrG1b is not required for Hcp1 secretion. Thus, VgrG1b does not require H1-T6SS for secretion nor does H1-T6SS require VgrG1b for its function. Finally, we show that VgrG proteins are required for secretion of a genuine H1-T6SS substrate, Tse3. Our results demonstrate that VgrG proteins are not only secreted components but are essential for secretion of other T6SS substrates. Overall, we emphasize variability in behavior of three P. aeruginosa VgrGs, suggesting that, although very similar, distinct VgrGs achieve specific functions. PMID:21325275

  6. Type VI secretion system in Pseudomonas aeruginosa: secretion and multimerization of VgrG proteins.

    PubMed

    Hachani, Abderrahman; Lossi, Nadine S; Hamilton, Alexander; Jones, Cerith; Bleves, Sophie; Albesa-Jové, David; Filloux, Alain

    2011-04-08

    Pseudomonas aeruginosa is a Gram-negative bacterium causing chronic infections in cystic fibrosis patients. Such infections are associated with an active type VI secretion system (T6SS), which consists of about 15 conserved components, including the AAA+ ATPase, ClpV. The T6SS secretes two categories of proteins, VgrG and Hcp. Hcp is structurally similar to a phage tail tube component, whereas VgrG proteins show similarity to the puncturing device at the tip of the phage tube. In P. aeruginosa, three T6SSs are known. The expression of H1-T6SS genes is controlled by the RetS sensor. Here, 10 vgrG genes were identified in the PAO1 genome, among which three are co-regulated with H1-T6SS, namely vgrG1a/b/c. Whereas VgrG1a and VgrG1c were secreted in a ClpV1-dependent manner, secretion of VgrG1b was ClpV1-independent. We show that VgrG1a and VgrG1c form multimers, which confirmed the VgrG model predicting trimers similar to the tail spike. We demonstrate that Hcp1 secretion requires either VgrG1a or VgrG1c, which may act independently to puncture the bacterial envelope and give Hcp1 access to the surface. VgrG1b is not required for Hcp1 secretion. Thus, VgrG1b does not require H1-T6SS for secretion nor does H1-T6SS require VgrG1b for its function. Finally, we show that VgrG proteins are required for secretion of a genuine H1-T6SS substrate, Tse3. Our results demonstrate that VgrG proteins are not only secreted components but are essential for secretion of other T6SS substrates. Overall, we emphasize variability in behavior of three P. aeruginosa VgrGs, suggesting that, although very similar, distinct VgrGs achieve specific functions.

  7. Horizontal Gene Transfer of Functional Type VI Killing Genes by Natural Transformation

    PubMed Central

    Thomas, Jacob; Watve, Samit S.; Ratcliff, William C.

    2017-01-01

    ABSTRACT Horizontal gene transfer (HGT) can have profound effects on bacterial evolution by allowing individuals to rapidly acquire adaptive traits that shape their strategies for competition. One strategy for intermicrobial antagonism often used by Proteobacteria is the genetically encoded contact-dependent type VI secretion system (T6SS), a weapon used to kill heteroclonal neighbors by direct injection of toxic effectors. Here, we experimentally demonstrate that Vibrio cholerae can acquire new T6SS effector genes via horizontal transfer and utilize them to kill neighboring cells. Replacement of one or more parental alleles with novel effectors allows the recombinant strain to dramatically outcompete its parent. Using spatially explicit modeling, we examine how this process could affect the ecology and evolution of surface-attached microbial populations. HGT of T6SS effector-immunity pairs is risky: transformation brings a cell into conflict with its former clone mates but can be adaptive when superior T6SS alleles are acquired. More generally, we find that these costs and benefits are not symmetric and that high rates of HGT can act as a hedge against competitors with unpredictable T6SS efficacy. We conclude that antagonism and horizontal transfer drive successive rounds of weapon optimization and selective sweeps, dynamically shaping the composition of microbial communities. PMID:28743812

  8. Determination of trehalose-6-phosphate in Arabidopsis seedlings by successive extractions followed by anion exchange chromatography-mass spectrometry.

    PubMed

    Delatte, Thierry L; Selman, Maurice H J; Schluepmann, Henriette; Somsen, Govert W; Smeekens, Sjef C M; de Jong, Gerhardus J

    2009-06-01

    A method for the detection of trehalose-6-phosphate (T6P) in tissue of the model plant Arabidopsis thaliana is presented. Liquid-liquid extraction (LLE) and mixed mode solid-phase extraction (SPE) were used for sample pretreatment followed by anion exchange chromatography (AEC) coupled with electrospray ionization mass spectrometry (MS) for highly selective quantitative analysis. LLE of plant material was performed with chloroform/acetonitrile/water (3:7:16, v/v/v) followed by SPE with Oasis MAX material, which significantly reduced the complexity of the extracts. On-line coupling of MS with gradient AEC using a sodium hydroxide eluent was accomplished with a postcolumn ion suppressor. The method allows specific quantification of T6P with good linearity for spiked plant extracts, from 80 nM to 1.3 microM (r(2)>0.98). The limit of detection in plant extracts was 40 nM. The recovery of the method was above 80% for relevant T6P levels. The method was applied to the determination of T6P in seedlings from four mutant A. thaliana lines (TRR1-4) resisting growth arrest caused by external supply of trehalose. Results reveal that T6P accumulation differed substantially in the four mutant lines and wild type (WT). It is concluded that the mutants circumvent the growth arrest observed in WT seedlings on 100mM trehalose by different mechanisms.

  9. Chemical intervention in plant sugar signalling increases yield and resilience

    NASA Astrophysics Data System (ADS)

    Griffiths, Cara A.; Sagar, Ram; Geng, Yiqun; Primavesi, Lucia F.; Patel, Mitul K.; Passarelli, Melissa K.; Gilmore, Ian S.; Steven, Rory T.; Bunch, Josephine; Paul, Matthew J.; Davis, Benjamin G.

    2016-12-01

    The pressing global issue of food insecurity due to population growth, diminishing land and variable climate can only be addressed in agriculture by improving both maximum crop yield potential and resilience. Genetic modification is one potential solution, but has yet to achieve worldwide acceptance, particularly for crops such as wheat. Trehalose-6-phosphate (T6P), a central sugar signal in plants, regulates sucrose use and allocation, underpinning crop growth and development. Here we show that application of a chemical intervention strategy directly modulates T6P levels in planta. Plant-permeable analogues of T6P were designed and constructed based on a ‘signalling-precursor’ concept for permeability, ready uptake and sunlight-triggered release of T6P in planta. We show that chemical intervention in a potent sugar signal increases grain yield, whereas application to vegetative tissue improves recovery and resurrection from drought. This technology offers a means to combine increases in yield with crop stress resilience. Given the generality of the T6P pathway in plants and other small-molecule signals in biology, these studies suggest that suitable synthetic exogenous small-molecule signal precursors can be used to directly enhance plant performance and perhaps other organism function.

  10. A Pseudomonas aeruginosa type VI secretion phospholipase D effector targets both prokaryotic and eukaryotic cells.

    PubMed

    Jiang, Feng; Waterfield, Nicholas R; Yang, Jian; Yang, Guowei; Jin, Qi

    2014-05-14

    Widely found in animal and plant-associated proteobacteria, type VI secretion systems (T6SSs) are potentially capable of facilitating diverse interactions with eukaryotes and/or other bacteria. Pseudomonas aeruginosa encodes three distinct T6SS haemolysin coregulated protein (Hcp) secretion islands (H1, H2, and H3-T6SS), each involved in different aspects of the bacterium's interaction with other organisms. Here we describe the characterization of a P. aeruginosa H3-T6SS-dependent phospholipase D effector, PldB, and its three tightly linked cognate immunity proteins. PldB targets the periplasm of prokaryotic cells and exerts an antibacterial activity. Surprisingly, PldB also facilitates intracellular invasion of host eukaryotic cells by activation of the PI3K/Akt pathway, revealing it to be a trans-kingdom effector. Our findings imply a potentially widespread T6SS-mediated mechanism, which deploys a single phospholipase effector to influence both prokaryotic cells and eukaryotic hosts. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. A widespread bacterial type VI secretion effector superfamily identified using a heuristic approach

    PubMed Central

    Russell, Alistair B.; Singh, Pragya; Brittnacher, Mitchell; Bui, Nhat Khai; Hood, Rachel D.; Carl, Mike A.; Agnello, Danielle M.; Schwarz, Sandra; Goodlett, David R.; Vollmer, Waldemar; Mougous, Joseph D.

    2012-01-01

    Summary Sophisticated mechanisms are employed to facilitate information exchange between interfacing bacteria. A type VI secretion system (T6SS) of Pseudomonas aeruginosa was shown to deliver cell wall-targeting effectors to neighboring cells. However, the generality of bacteriolytic effectors, and moreover, of antibacterial T6S, remained unknown. Using parameters derived from experimentally validated bacterial T6SS effectors and informatics, we identified a phylogenetically disperse superfamily of T6SS-associated peptidoglycan-degrading effectors. The effectors separate into four families composed of peptidoglycan amidase enzymes of differing specificities. Effectors strictly co-occur with cognate immunity proteins, indicating that self-intoxication is a general property of antibacterial T6SSs and effector delivery by the system exerts a strong selective pressure in nature. The presence of antibacterial effectors in a plethora of organisms, including many that inhabit or infect polymicrobial niches in the human body, suggests that the system could mediate interbacterial interactions of both environmental and clinical significance. PMID:22607806

  12. Francisella requires dynamic type VI secretion system and ClpB to deliver effectors for phagosomal escape

    PubMed Central

    Brodmann, Maj; Dreier, Roland F.; Broz, Petr; Basler, Marek

    2017-01-01

    Francisella tularensis is an intracellular pathogen that causes the fatal zoonotic disease tularaemia. Critical for its pathogenesis is the ability of the phagocytosed bacteria to escape into the cell cytosol. For this, the bacteria use a non-canonical type VI secretion system (T6SS) encoded on the Francisella pathogenicity island (FPI). Here we show that in F. novicida T6SS assembly initiates at the bacterial poles both in vitro and within infected macrophages. T6SS dynamics and function depends on the general purpose ClpB unfoldase, which specifically colocalizes with contracted sheaths and is required for their disassembly. T6SS assembly depends on iglF, iglG, iglI and iglJ, whereas pdpC, pdpD, pdpE and anmK are dispensable. Importantly, strains lacking pdpC and pdpD are unable to escape from phagosome, activate AIM2 inflammasome or cause disease in mice. This suggests that PdpC and PdpD are T6SS effectors involved in phagosome rupture. PMID:28621333

  13. Towards a complete structural deciphering of Type VI secretion system.

    PubMed

    Nguyen, Van Son; Douzi, Badreddine; Durand, Eric; Roussel, Alain; Cascales, Eric; Cambillau, Christian

    2018-02-01

    The Type VI secretion system (T6SS) is a dynamic nanomachine present in many Gram-negative bacteria. Using a contraction mechanism similar to that of myophages, bacteriocins or anti-feeding prophages, it injects toxic effectors into both eukaryotic and prokaryotic cells. T6SS assembles three large ensembles: the trans-membrane complex (TMC), the baseplate and the tail. Recently, the tail structure has been elucidated by cryo electron microscopy (cryoEM) in extended and contracted forms. The structure of the trans-membrane complex has been deciphered using a combination of X-ray crystallography and EM. However, the structural characterisation of the baseplate lags behind and should be the target of future studies. Finally, cryo-tomography should provide low/medium resolution maps allowing to assemble the different parts ultimately leading to a complete structural description of T6SS. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. The analysis of aluminum alloy structure beams under static load

    NASA Astrophysics Data System (ADS)

    Ho, Minghsiung; Wang, Pinning; Yeh, Jungpeng

    2017-04-01

    The Aluminum alloy had been applications in many areas. In this study, the models with four type's cross-section were designed and analyzed. Analyses of the use of aluminum alloy materials are 5086-H32, 6061-T6, 7005-T6 and 7075-T6. The materials selected are based on the recommendations of the casting plant. The boundary conditions are set according to the actual conditions of use. Force and torsion are used to apple on models under different conditions. The results of stress and deformation are discussed. The stress results were shown that 40x80 model with hollow cross-section under two end fixed middle beam load had the highest stresses of 41.177 MPa nearby fixed end position. The beam model of 40x80 hollow cross-section under boundary condition of one end fixed and one end force load like a cantilever beam has the maximum deformation 1.587 mm.

  15. Index to Watervliet Arsenal Technical Reports, 1973

    DTIC Science & Technology

    1973-09-01

    Huang , Y. K. ’i-WV-T-18-73 M-WV -T-1-1O-7’ Anderson, Gary L. Hussain, NM. A. H-WV-T-6-50-73 R-WV-T-6-3l-73* R-WV-T-2-46-73 R-wV---6-h8-7311 R-WV-T-2...73 Ignition Lag Guns, 20-30 M R-WV-S-3-5-73 M-WV-T-l-25-73 li- V-T-l-23-73 Impact Strength R-WV-T-6-49-73* Guns, 105 M liW---57 Integral Equations R-WV...initiator (firing unit) -propellant ignition train intertm’ being achieved. ROPACI OSRO wai. JA5.EUOR16D ’..%17 1’ s R~.VEPRLC S Unclassi fied k3lY

  16. Killing by Type VI secretion drives genetic phase separation and correlates with increased cooperation

    NASA Astrophysics Data System (ADS)

    McNally, Luke; Bernardy, Eryn; Thomas, Jacob; Kalziqi, Arben; Pentz, Jennifer; Brown, Sam P.; Hammer, Brian K.; Yunker, Peter J.; Ratcliff, William C.

    2017-02-01

    By nature of their small size, dense growth and frequent need for extracellular metabolism, microbes face persistent public goods dilemmas. Genetic assortment is the only general solution stabilizing cooperation, but all known mechanisms structuring microbial populations depend on the availability of free space, an often unrealistic constraint. Here we describe a class of self-organization that operates within densely packed bacterial populations. Through mathematical modelling and experiments with Vibrio cholerae, we show how killing adjacent competitors via the Type VI secretion system (T6SS) precipitates phase separation via the `Model A' universality class of order-disorder transition mediated by killing. We mathematically demonstrate that T6SS-mediated killing should favour the evolution of public goods cooperation, and empirically support this prediction using a phylogenetic comparative analysis. This work illustrates the twin role played by the T6SS, dealing death to local competitors while simultaneously creating conditions potentially favouring the evolution of cooperation with kin.

  17. 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

  18. Mechanical Properties and Fracture Behaviors of GTA-Additive Manufactured 2219-Al After an Especial Heat Treatment

    NASA Astrophysics Data System (ADS)

    Bai, J. Y.; Fan, C. L.; Lin, S. B.; Yang, C. L.; Dong, B. L.

    2017-04-01

    2219-Al parts were produced by gas tungsten arc-additive manufacturing and sequentially processed by an especial heat treatment. In order to investigate the effects of heat treatment on its mechanical properties, multiple tests were conducted. Hardness tests were carried out on part scale and layer scale along with tensile tests which were performed on welding and building directions. Results show that compared to conventional casting + T6 2219-Al, the current deposit + T6 2219-Al exhibits satisfying properties with regard to strength but unsatisfying results in plasticity. Additionally, anisotropy is significant. Fractures were observed and the cracks' propagating paths in both directional specimens are described. The effects of heat treatment on the cracks' initiation and propagation were also investigated. Ultimately, a revised formula was developed to calculate the strength of the deposit + T6 2219-Al. The aforementioned formula, which takes into consideration the belt-like porosities-distributing feature, can scientifically describe the anisotropic properties in the material.

  19. Identification of an Inhibitory Alcohol Binding Site in GABAA ρ1 Receptors

    PubMed Central

    Borghese, Cecilia M.; Ruiz, Carlos I.; Lee, Ui S.; Cullins, Madeline A.; Bertaccini, Edward J.; Trudell, James R.; Harris, R. Adron

    2016-01-01

    Alcohols inhibit γ-aminobutyric acid type A ρ1 receptor function. After introducing mutations in several positions of the second transmembrane helix in ρ1, we studied the effects of ethanol and hexanol on GABA responses using two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes. The 6′ mutations produced the following effects on ethanol and hexanol responses: small increase or no change (T6′M), increased inhibition (T6′V) and small potentiation (T6′Y and T6′F). The 5′ mutations produced mainly increases in hexanol inhibition. Other mutations produced small (3′ and 9′) or no changes (2′ and L277 in the first transmembrane domain) in alcohol effects. These results suggest an inhibitory alcohol binding site near the 6′ position. Homology models of ρ1 receptors based on the X-ray structure of GluCl showed that the 2′, 5′, 6’ and 9′ residues were easily accessible from the ion pore, with 5′ and 6′ residues from neighboring subunits facing each other; L3′ and L277 also faced the neighboring subunit. We tested ethanol through octanol on single and double mutated ρ1 receptors [ρ1(I15′S), ρ1(T6′Y) and ρ1(T6′Y,I15′S)] to further characterize the inhibitory alcohol pocket in the wild-type ρ1 receptor. The pocket can only bind relatively short-chain alcohols and is eliminated by introducing Y in the 6’ position. Replacing the bulky 15′ residue with a smaller side chain introduced a potentiating binding site, more sensitive to long-chain than to short-chain alcohols. In conclusion, the net alcohol effect on the ρ1 receptor is determined by the sum of its actions on inhibitory and potentiating sites. PMID:26571107

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

    PubMed Central

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

    2012-01-01

    Pseudomonas aeruginosa is capable of injecting protein toxins into other bacterial cells through one of its three type VI secretion systems (T6SS). 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 Thr 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 export of Hcp1 and Tse1. 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 signaling pathway that promotes H1-T6SS activity under optimal environmental conditions. PMID:22765374

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

    PubMed

    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 CCl4-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. © 2013.

  2. Signal Processing Aspects of Nonlinear Acoustics.

    DTIC Science & Technology

    1980-07-07

    P r-AoB 369 TEXAS NIV AT AUSTIN APPLIED RESEARCH LABS F/6 20/1 SIGNAL PROCESSING ASPECTS OF NONLINEAR ACOUSTICS .(U) JUL 80 T 6 NUIR. T 6 GOLOSBERRY...N0001-75-C-0161 UNCLASSIFIED ARL-TR-80-38 NL END uuuuuuu/////i ANRL-Tfta44 V/ Copy ft~~.. SINAL PROCESSING ASPECTS OF NONLINEAR ACOUSTIC T. a. Muir...22217y SIGNAL PROCESSING ASPECTS OF NONLINEAR ACOUSTICS _I " / Iby T. G.,/Muir 40 G./Goldsberry / ’Applied Research Laboratories The University of Texas

  3. Corrosion Protection Mechanisms of Rare-Earth Compounds Based on Cerium and Praseodymium

    DTIC Science & Technology

    2012-04-01

    electrolyte consisted of 0.35 wt. % NaCl + 0.70 wt. % (NH4)2SO4. ........... 58   Figure 35.   EIS analysis of CeCCs deposited on Al 7075-T6 from...Figure 47.   Pits developed after EIS testing using a test electrolyte of pH 5.5: (a) optical image of the 1 cm2 test area showing white salt tails...7075-T6 using a test electrolyte of pH 9.0 for various surface treatments

  4. Reactions of Mo2(OR)6 (M triple bond M) Compounds (R = Pr(i) and Bu(t) with Benzoyl Peroxide.

    DTIC Science & Technology

    1982-11-01

    molybdenum containing compound. These products are proposed to arise from decomposition (disproportionation) of Mo(OB t)6 (O2 CPh)’ (M=M). The Mo2 ( OBu ...change from orange to blue which implies oxidative-addition to give Mo2 ( OBu t )6 (O2CPh) 2. However, with continued stirring, pale yellow-green...crystals are formed and the solution turns purple. The crystalline precipitate has been identified as Mo2 ( OBu t 𔃾 - t (02CPh)2 (see below) and we believe

  5. Rivet Qualification of Aluminum Alloy 7050.

    DTIC Science & Technology

    1976-10-01

    Driving Test Specimen After All Slugs Upset to Form Flat Heads- 0.184-in. Diameter 7050 Slugs Driven in 0.190-in. 7075-T6 Sheet . . 92 9 Photograph of... Sheet ... ........... ... 96 13 Photomacrographs of Sectioned 0.184-in. Diamete±v (D) 7050 Slugs Driven With 1.5D and 1.7D Diameter Flat Heads in 0.190...in. 7075-T6 Sheet . 97 14 Photomacrographs of Sectioned 0.184-in. Diameter (D) 2024-T31 Slugs Driven (in the "Freshly" Quenched Condition) With 1.5D

  6. An immune-modulating diet increases the regulatory T cells and reduces T helper 1 inflammatory response in Leishmaniosis affected dogs treated with standard therapy.

    PubMed

    Cortese, Laura; Annunziatella, Mariangela; Palatucci, Anna Teresa; Lanzilli, Sarah; Rubino, Valentina; Di Cerbo, Alessandro; Centenaro, Sara; Guidetti, Gianandrea; Canello, Sergio; Terrazzano, Giuseppe

    2015-12-03

    Clinical appearance and evolution of Canine Leishmaniosis (CL) are the consequence of complex interactions between the parasite and the genetic and immunological backgrounds. We investigated the effect of an immune-modulating diet in CL. Dogs were treated with anti- Leishmania pharmacological therapy combined with standard diet (SD Group) or with the immune-modulating diet (IMMD Group). CD3+ CD4+ Foxp3+ Regulatory T cells (Treg) and CD3+ CD4+ IFN-γ + T helper 1 (Th1) were analyzed by flow cytometry. All sick dogs showed low platelet number at diagnosis (T0). A platelet increase was observed after six months (T6) SD Group, with still remaining in the normal range at twelve months (T12). IMMD Group showed an increase in platelet number becoming similar to healthy dogs at T6 and T12. An increase of CD4/CD8 ratio was revealed in SD Group after three months (T3), while at T6 and at T12 the values resembled to T0. The increase in CD4/CD8 ratio at T3 was maintained at T6 and T12 in IMMD Group. A reduction in the percentage of Treg of all sick dogs was observed at T0. A recovery of Treg percentage was observed only at T3 in SD Group, while this effect disappeared at T6 and T12. In contrast, Treg percentage became similar to healthy animals in IMDD Group at T3, T6 and T12. Sick dogs showed an increase of Th1 cells at T0 as compared with healthy dogs. We observed the occurrence of a decrease of Th1 cells from T3 to T12 in SD Group, although a trend of increase was observed at T6 and T12. At variance, IMMD Group dogs showed a progressive decrease of Th1 cells, whose levels became similar to healthy controls at T6 and T12. The immune-modulating diet appears to regulate the immune response in CL during the standard pharmacological treatment. The presence of nutraceuticals in the diet correlates with the decrease of Th1 cells and with the increase of Treg in sick dogs. Therefore, the administration of the specific dietary supplement improved the clinical response to the

  7. 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

  8. Qualification of Life Extension Schemes for Engine Components (Homologation des Programmes de Prolongation du cycle de vie des Organes Moteur)

    DTIC Science & Technology

    1999-03-01

    des mat ~ riaux utilis~s, trois autres d~crivent des m~thodes sp~cifiques de reparation, tandis que trois autres encore se penchent sur les proc6dures et...propri~t6s des mat ~ riaux . Enfin ii a 6t6 soulign6 qu’il n’existait aucune m6thode reconnue pour faire face aux probl~mes de fatigue vibratoire engendr...causing In conjunction with an intelligent on-board life monitoring high repair and spare part costs. system the total life potential of an individual

  9. Assessment of GPR30, a Seven Transmembrane-spanning Estrogen Receptor, as an Oncogene

    DTIC Science & Technology

    2009-10-01

    this newly appreciated mem brane estroge n rece ptor in breas t cancer . We successfully generated two founder m ice (T6-1A and T6-2E) that cont ained...al, 2006). Altered expression of 7TMRs is linked with a spectrum of disease phenotypes, including cancer , raising the possibility that GPR30 may... cancer are largely d etermined by the measurement of known estrog en receptors (ERs) in primary tum or biopsy specim ens. However, it has lo ng been sus

  10. Intraspecies Competition in Serratia marcescens Is Mediated by Type VI-Secreted Rhs Effectors and a Conserved Effector-Associated Accessory Protein.

    PubMed

    Alcoforado Diniz, Juliana; Coulthurst, Sarah J

    2015-07-01

    The type VI secretion system (T6SS) is widespread in Gram-negative bacteria and can deliver toxic effector proteins into eukaryotic cells or competitor bacteria. Antibacterial T6SSs are increasingly recognized as key mediators of interbacterial competition and may contribute to the outcome of many polymicrobial infections. Multiple antibacterial effectors can be delivered by these systems, with diverse activities against target cells and distinct modes of secretion. Polymorphic toxins containing Rhs repeat domains represent a recently identified and as-yet poorly characterized class of T6SS-dependent effectors. Previous work had revealed that the potent antibacterial T6SS of the opportunistic pathogen Serratia marcescens promotes intraspecies as well as interspecies competition (S. L. Murdoch, K. Trunk, G. English, M. J. Fritsch, E. Pourkarimi, and S. J. Coulthurst, J Bacteriol 193:6057-6069, 2011, http://dx.doi.org/10.1128/JB.05671-11). In this study, two new Rhs family antibacterial effectors delivered by this T6SS have been identified. One of these was shown to act as a DNase toxin, while the other contains a novel, cytoplasmic-acting toxin domain. Importantly, using S. marcescens, it has been demonstrated for the first time that Rhs proteins, rather than other T6SS-secreted effectors, can be the primary determinant of intraspecies competition. Furthermore, a new family of accessory proteins associated with T6SS effectors has been identified, exemplified by S. marcescens EagR1, which is specifically required for deployment of its associated Rhs effector. Together, these findings provide new insight into how bacteria can use the T6SS to deploy Rhs-family effectors and mediate different types of interbacterial interactions. Infectious diseases caused by bacterial pathogens represent a continuing threat to health and economic prosperity. To counter this threat, we must understand how such organisms survive and prosper. The type VI secretion system is a weapon that

  11. Intraspecies Competition in Serratia marcescens Is Mediated by Type VI-Secreted Rhs Effectors and a Conserved Effector-Associated Accessory Protein

    PubMed Central

    Alcoforado Diniz, Juliana

    2015-01-01

    ABSTRACT The type VI secretion system (T6SS) is widespread in Gram-negative bacteria and can deliver toxic effector proteins into eukaryotic cells or competitor bacteria. Antibacterial T6SSs are increasingly recognized as key mediators of interbacterial competition and may contribute to the outcome of many polymicrobial infections. Multiple antibacterial effectors can be delivered by these systems, with diverse activities against target cells and distinct modes of secretion. Polymorphic toxins containing Rhs repeat domains represent a recently identified and as-yet poorly characterized class of T6SS-dependent effectors. Previous work had revealed that the potent antibacterial T6SS of the opportunistic pathogen Serratia marcescens promotes intraspecies as well as interspecies competition (S. L. Murdoch, K. Trunk, G. English, M. J. Fritsch, E. Pourkarimi, and S. J. Coulthurst, J Bacteriol 193:6057–6069, 2011, http://dx.doi.org/10.1128/JB.05671-11). In this study, two new Rhs family antibacterial effectors delivered by this T6SS have been identified. One of these was shown to act as a DNase toxin, while the other contains a novel, cytoplasmic-acting toxin domain. Importantly, using S. marcescens, it has been demonstrated for the first time that Rhs proteins, rather than other T6SS-secreted effectors, can be the primary determinant of intraspecies competition. Furthermore, a new family of accessory proteins associated with T6SS effectors has been identified, exemplified by S. marcescens EagR1, which is specifically required for deployment of its associated Rhs effector. Together, these findings provide new insight into how bacteria can use the T6SS to deploy Rhs-family effectors and mediate different types of interbacterial interactions. IMPORTANCE Infectious diseases caused by bacterial pathogens represent a continuing threat to health and economic prosperity. To counter this threat, we must understand how such organisms survive and prosper. The type VI secretion

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

    SciTech Connect

    Fang, Ling, E-mail: fangling_1984@126.com; Zhan, Shuxiang; Huang, Cheng

    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 increasemore » 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.« less

  13. Comparative genomic analysis uncovers 3 novel loci encoding type six secretion systems differentially distributed in Salmonella serotypes

    PubMed Central

    2009-01-01

    Background The recently described Type VI Secretion System (T6SS) represents a new paradigm of protein secretion in bacteria. A number of bioinformatic studies have been conducted to identify T6SS gene clusters in the available bacterial genome sequences. According to these studies, Salmonella harbors a unique T6SS encoded in the Salmonella Pathogenicity Island 6 (SPI-6). Since these studies only considered few Salmonella genomes, the present work aimed to identify novel T6SS loci by in silico analysis of every genome sequence of Salmonella available. Results The analysis of sequencing data from 44 completed or in progress Salmonella genome projects allowed the identification of 3 novel T6SS loci. These clusters are located in differentially-distributed genomic islands we designated SPI-19, SPI-20 and SPI-21, respectively. SPI-19 was identified in a subset of S. enterica serotypes including Dublin, Weltevreden, Agona, Gallinarum and Enteritidis. In the later, an internal deletion eliminated most of the island. On the other hand, SPI-20 and SPI-21 were restricted to S. enterica subspecies arizonae (IIIa) serotype 62:z4,z23:-. Remarkably, SPI-21 encodes a VgrG protein containing a C-terminal extension similar to S-type pyocins of Pseudomonas aeruginosa. This is not only the first evolved VgrG described in Salmonella, but also the first evolved VgrG including a pyocin domain described so far in the literature. In addition, the data indicate that SPI-6 T6SS is widely distributed in S. enterica and absent in serotypes Enteritidis, Gallinarum, Agona, Javiana, Paratyphi B, Virchow, IIIa 62:z4,z23:- and IIIb 61:1,v:1,5,(7). Interestingly, while some serotypes harbor multiple T6SS (Dublin, Weltvreden and IIIa 62:z4,z23:-) others do not encode for any (Enteritidis, Paratyphi B, Javiana, Virchow and IIIb 61:1,v:1,5,(7)). Comparative and phylogenetic analyses indicate that the 4 T6SS loci in Salmonella have a distinct evolutionary history. Finally, we identified an orphan Hcp

  14. Environmental Impact Analysis Process, Groom Mountain Range, Lincoln County, Nevada

    DTIC Science & Technology

    1985-10-01

    occasional 6) T6S, R56E, Sec. 19, 7800 feet, few Erigeron ovinus occurs in crevices, with shallow, coarse soil on lime - stone, typically at the base...Phrynosoma phatyrhinos) X X X Sagebrush lizard (Sceloperous graciosus) X X X Western fence lizard (Sceloperous occidentalis) X X X X Side blotched lizard

  15. Comparative Evaluation of Cast Aluminum Alloys for Automotive Cylinder Heads: Part I—Microstructure Evolution

    NASA Astrophysics Data System (ADS)

    Roy, Shibayan; Allard, Lawrence F.; Rodriguez, Andres; Watkins, Thomas R.; Shyam, Amit

    2017-05-01

    The present study stages a comparative evaluation of microstructure and associated mechanical and thermal response for common cast aluminum alloys that are used for manufacturing automotive cylinder heads. The systems considered are Al-Cu (206-T6), Al-Si-Cu (319-T7), and Al-Si (356-T6, A356-T6, and A356 + 0.5Cu-T6). The focus of the present manuscript is on the evaluation of microstructure at various length scales after aging, while the second manuscript will deal with the mechanical and thermal response of these alloys due to short-term (aging) and long-term (pre-conditioning) heat treatments. At the grain-scale, the Al-Cu alloy possessed an equiaxed microstructure as opposed to the dendritic structure for the Al-Si-Cu or Al-Si alloys which is related to the individual solidification conditions for these alloy systems. The composition and morphology of intermetallic precipitates within the grain and at the grain/dendritic boundary are dictated by the alloy chemistry, solidification, and heat treatment conditions. At the nanoscale, these alloys contain various metastable strengthening precipitates (GPI and θ^'' in Al-Cu alloy, θ^' in Al-Si-Cu alloy, and β^' in Al-Si alloys) with varying size, morphology, coherency, and thermal stability.

  16. 33. Photographic copy of original construction drawing, dated May 22, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. Photographic copy of original construction drawing, dated May 22, 1951 (from paper copy at Engineering Flight, Ellsworth Air Force Base, SD). Readiness hangar structural: details of trusses T2 to T6. - Ellsworth Air Force Base, Readiness Hangar, Kenny Road, southeast corner of interstction with G Avenue, Blackhawk, Meade County, SD

  17. 27 CFR 9.163 - Salado Creek.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Patterson Quadrangle map, section 19, T6S, R8E, at the intersection of Interstate Highway 5 and Fink Road... Landing Quadrangle map, to its intersection with an unnamed, unimproved road on the south side of Elfers..., R8E; then (9) Follow Marshall Road straight west 1.1 miles, crossing onto the USGS Patterson map, to...

  18. 27 CFR 9.163 - Salado Creek.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Patterson Quadrangle map, section 19, T6S, R8E, at the intersection of Interstate Highway 5 and Fink Road... Landing Quadrangle map, to its intersection with an unnamed, unimproved road on the south side of Elfers..., R8E; then (9) Follow Marshall Road straight west 1.1 miles, crossing onto the USGS Patterson map, to...

  19. 27 CFR 9.163 - Salado Creek.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Patterson Quadrangle map, section 19, T6S, R8E, at the intersection of Interstate Highway 5 and Fink Road... Landing Quadrangle map, to its intersection with an unnamed, unimproved road on the south side of Elfers..., R8E; then (9) Follow Marshall Road straight west 1.1 miles, crossing onto the USGS Patterson map, to...

  20. 27 CFR 9.163 - Salado Creek.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Patterson Quadrangle map, section 19, T6S, R8E, at the intersection of Interstate Highway 5 and Fink Road... Landing Quadrangle map, to its intersection with an unnamed, unimproved road on the south side of Elfers..., R8E; then (9) Follow Marshall Road straight west 1.1 miles, crossing onto the USGS Patterson map, to...

  1. 27 CFR 9.163 - Salado Creek.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Patterson Quadrangle map, section 19, T6S, R8E, at the intersection of Interstate Highway 5 and Fink Road... Landing Quadrangle map, to its intersection with an unnamed, unimproved road on the south side of Elfers..., R8E; then (9) Follow Marshall Road straight west 1.1 miles, crossing onto the USGS Patterson map, to...

  2. Structure-Function Analysis of the C-Terminal Domain of the Type VI Secretion TssB Tail Sheath Subunit.

    PubMed

    Douzi, Badreddine; Logger, Laureen; Spinelli, Silvia; Blangy, Stéphanie; Cambillau, Christian; Cascales, Eric

    2018-02-02

    The type VI secretion system (T6SS) is a specialized macromolecular complex dedicated to the delivery of protein effectors into both eukaryotic and bacterial cells. The general mechanism of action of the T6SS is similar to the injection of DNA by contractile bacteriophages. The cytoplasmic portion of the T6SS is evolutionarily, structurally and functionally related to the phage tail complex. It is composed of an inner tube made of stacked Hcp hexameric rings, engulfed within a sheath and built on a baseplate. This sheath undergoes cycles of extension and contraction, and the current model proposes that the sheath contraction propels the inner tube toward the target cell for effector delivery. The sheath comprises two subunits: TssB and TssC that polymerize under an extended conformation. Here, we show that isolated TssB forms trimers, and we report the crystal structure of a C-terminal fragment of TssB. This fragment comprises a long helix followed by a helical hairpin that presents surface-exposed charged residues. Site-directed mutagenesis coupled to functional assay further showed that these charges are required for proper assembly of the sheath. Positioning of these residues in the extended T6SS sheath structure suggests that they may mediate contacts with the baseplate. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Interactions of satellite-speed helium atoms with satellite surfaces. 3: Drag coefficients from spatial and energy distributions of reflected helium atoms

    NASA Technical Reports Server (NTRS)

    Sharma, P. K.; Knuth, E. L.

    1977-01-01

    Spatial and energy distributions of helium atoms scattered from an anodized 1235-0 aluminum surface as well as the tangential and normal momentum accommodation coefficients calculated from these distributions are reported. A procedure for calculating drag coefficients from measured values of spatial and energy distributions is given. The drag coefficient calculated for a 6061 T-6 aluminum sphere is included.

  4. Continuous internal channels formed in aluminum fusion welds

    NASA Technical Reports Server (NTRS)

    Gault, J.; Sabo, W.

    1967-01-01

    Process produces continuous internal channel systems on a repeatable basis in 2014-T6 aluminum. Standard machining forms the initial channel, which is filled with tungsten carbide powder. TIG machine fusion welding completes formation of the channel. Chem-mill techniques enlarge it to the desired size.

  5. 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.

  6. The Processing and Mechanical Properties of High Temperature/High Performance Composites. Book 4, Section 3: Flow and Creep Strength

    DTIC Science & Technology

    1989-10-15

    contribution lowers the mode I component required to Initiate fracture. However, Pook 163 found that mode I fractura toughness was independent of transverse...mode I and mode III components. From the geomrety of figure 3, one can writex P1 - P sine , - P cogi (2)and, Pl t6 1 6 vsine - h come, 6II 6 v Coll

  7. 76 FR 2084 - North Pacific Fishery Management Council; Public Meetings

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-12

    ... (HAPC)--Skate sites; Initial review for EFH Amendment(T). 6. Aleutian Island (AI) Pacific Cod Issues: Discussion paper on BS&AI Pacific cod Split take action as necessary; Initial review AI Pacific cod... following issues: 1. Salmon Bycatch. 2. EFH. 3. AI Pacific Cod. 4. BSAI Crab Management. 5. Miscellaneous...

  8. 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.

  9. 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.

  10. 77 FR 25642 - Airworthiness Directives; Bombardier, Inc. Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-01

    ... manufactured with tubes having the incorrect heat treatment. This proposed AD would require replacing the... incorrect heat treatment, using 6061-T4 instead of 6061- T6. The incorrect heat treatment appreciably... having the incorrect heat treatment. We are issuing this AD to prevent loss of rudder control, reduced...

  11. 77 FR 47277 - Airworthiness Directives; Bombardier, Inc. Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-08

    ... with tubes having the incorrect heat treatment. This AD requires replacing the affected pushrod... the DHC-8 Series 100/200/300/400 aeroplanes had been manufactured with tubes having the incorrect heat treatment, using 6061-T4 instead of 6061- T6. The incorrect heat treatment appreciably degrades the strength...

  12. Microstructure and Thermal Stability of A357 Alloy With and Without the Addition of Zr

    NASA Astrophysics Data System (ADS)

    Tzeng, Yu-Chih; Chengn, Vun-Shing; Nieh, Jo-Kuang; Bor, Hui-Yun; Lee, Sheng-Long

    2017-11-01

    The principal purpose of this research was to evaluate the effects of Zr on the microstructure and thermal stability of an A357 alloy that has been subjected to an aging treatment (T6) and thermal exposure (250 °C). The results show that the addition of Zr had a significant influence on the refinement of the grain size, which enhanced the hardness and tensile strength of the A357 alloy under the T6 condition. During thermal exposure at 250 °C, the rodlike metastable β'-Mg2Si precipitates transformed into coarse equilibrium phase β-Mg2Si precipitates, resulting in a significant drop in the hardness and tensile strength of the T6 heat-treated A357 alloy. However, after thermal exposure, coherent, finely dispersed Al3Zr precipitates were found to be formed in the T6 heat-treated A357 alloy. The addition of 0.1% Zr played a critical role in improving the high-temperature strength. Consequently, the A357 alloy with the addition of Zr demonstrated better mechanical properties at room temperature and high temperature than the alloy without Zr, in terms of both microstructure and thermal stability.

  13. 40 CFR 147.2554 - Aquifer exemptions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... currently being used for injection in connection with Class II (oil and gas) injection operations on the... 3,400-3,600 T6N, R3W—SE/4 Sec. 35, SW/4 Sec. 36.T5N, R3W—N/2 Sec. 1. Circle Ridge Field Tensleep 1...

  14. 40 CFR 147.2554 - Aquifer exemptions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... currently being used for injection in connection with Class II (oil and gas) injection operations on the... 3,400-3,600 T6N, R3W—SE/4 Sec. 35, SW/4 Sec. 36.T5N, R3W—N/2 Sec. 1. Circle Ridge Field Tensleep 1...

  15. 40 CFR 147.2554 - Aquifer exemptions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... currently being used for injection in connection with Class II (oil and gas) injection operations on the... 3,400-3,600 T6N, R3W—SE/4 Sec. 35, SW/4 Sec. 36.T5N, R3W—N/2 Sec. 1. Circle Ridge Field Tensleep 1...

  16. 40 CFR 147.2554 - Aquifer exemptions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... currently being used for injection in connection with Class II (oil and gas) injection operations on the... 3,400-3,600 T6N, R3W—SE/4 Sec. 35, SW/4 Sec. 36.T5N, R3W—N/2 Sec. 1. Circle Ridge Field Tensleep 1...

  17. Predicted geographic ranges for North American sylvatic Trichinella

    USDA-ARS?s Scientific Manuscript database

    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...

  18. Ex Vivo Smooth Muscle Pharmacological Effects of a Novel Bradykinin-Related Peptide, and Its Analogue, from Chinese Large Odorous Frog, Odorrana livida Skin Secretions

    PubMed Central

    Xiang, Jie; Wang, Hui; Ma, Chengbang; Zhou, Mei; Wu, Yuxin; Wang, Lei; Guo, Shaodong; Chen, Tianbao; Shaw, Chris

    2016-01-01

    Bradykinin-related peptides (BRPs) are one of the most extensively studied frog secretions-derived peptide families identified from many amphibian species. The diverse primary structures of BRPs have been proven essential for providing valuable information in understanding basic mechanisms associated with drug modification. Here, we isolated, identified and characterized a dodeca-BRP (RAP-L1, T6-BK), with primary structure RAPLPPGFTPFR, from the skin secretions of Chinese large odorous frogs, Odorrana livida. This novel peptide exhibited a dose-dependent contractile property on rat bladder and rat ileum, and increased the contraction frequency on rat uterus ex vivo smooth muscle preparations; it also showed vasorelaxant activity on rat tail artery smooth muscle. In addition, the analogue RAP-L1, T6, L8-BK completely abolished these effects on selected rat smooth muscle tissues, whilst it showed inhibition effect on bradykinin-induced rat tail artery relaxation. By using canonical antagonist for bradykinin B1 or B2 type receptors, we found that RAP-L1, T6-BK -induced relaxation of the arterial smooth muscle was very likely to be modulated by B2 receptors. The analogue RAP-L1, T6, L8-BK further enhanced the bradykinin inhibitory activity only under the condition of co-administration with HOE140 on rat tail artery, suggesting a synergistic inhibition mechanism by which targeting B2 type receptors. PMID:27690099

  19. 77 FR 76069 - Notice of Proposed Class II Reinstatement of Terminated Oil and Gas Lease, Utah

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-26

    ... 200 South, Salt Lake City, UT, 84145, phone 801-539-4063. Persons who use a telecommunications device...) $159 for the cost of publishing this notice. Salt Lake Meridian T. 6 S., R 23 E., Sec. 29, S1/2; Sec...: Bureau of Land Management, Utah State Office, Attn: Kent Hoffman, P.O. Box 45155, Salt Lake City, UT...

  20. 75 FR 26788 - Public Land Order No. 7742; Withdrawal of Public Land for the Manning Canyon Tailings Repository; UT

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    .... DATES: Effective Date: May 12, 2010. FOR FURTHER INFORMATION CONTACT: Mike Nelson, BLM Salt Lake Field Office, 2370 South 2300 West, Salt Lake City, Utah 84119, 801-977-4355. SUPPLEMENTARY INFORMATION: The...., to protect the Manning Canyon Tailings Repository for a period of 5 years: Salt Lake Meridian T. 6 S...

  1. 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...

  2. Crystal structure of YwpF from Staphylococcus aureus reveals its architecture comprised of a β-barrel core domain resembling type VI secretion system proteins and a two-helix pair.

    PubMed

    Lee, Sang Jae; Lee, Kyu-Yeon; Lee, Ki-Young; Kim, Dong-Gyun; Kim, Soon-Jong; Lee, Bong-Jin

    2015-04-01

    The ywpF gene (SAV2097) of the Staphylococcus aureus strain Mu50 encodes the YwpF protein, which may play a role in antibiotic resistance. Here, we report the first crystal structure of the YwpF superfamily from S. aureus at 2.5-Å resolution. The YwpF structure consists of two regions: an N-terminal core β-barrel domain that shows structural similarity to type VI secretion system (T6SS) proteins (e.g., Hcp1, Hcp3, and EvpC) and a C-terminal two-helix pair. Although the monomer structure of S. aureus YwpF resembles those of T6SS proteins, the dimer/tetramer model of S. aureus YwpF is distinct from the functionally important hexameric ring of T6SS proteins. We therefore suggest that the S. aureus YwpF may have a different function compared to T6SS proteins. © 2015 Wiley Periodicals, Inc.

  3. Design Validation Tests on a Realistic Hypersonic Waverider at Mach 10, 14, and 16.5 in the Naval Surface Warfare Center Hypervelocity Wind Tunnel No. 9

    DTIC Science & Technology

    1994-05-05

    manufactured from 6061-T6 aluminum. The nose, both leading edges, and the main cavity cover plate were manufactured from 17-4 PH stainless steel . The final...for a homogeneous planar slab of finite thickness, as discussed in References 4 and 5. The thermocouples were mounted In 17-4 PH stainless steel , using

  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, 2013 CFR

    2013-10-01

    ... for DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180 Transportation... Pt. 180, App. C Appendix C to Part 180—Eddy Current Examination With Visual Inspection for DOT 3AL... with CGA pamphlet C-6.1 (IBR; see § 171.7 of this subchapter). 3. Eddy Current Equipment. A reference...

  5. 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.

  6. Diversity Performance in Frequency-Hopped 8-ARY Signals-Implementation and Measurements

    DTIC Science & Technology

    1990-06-01

    processeur pour le traitement de signaux a t6 developp6 en laboratoire afin d’exdcuter la combinaison en diversit6 requise A bord du satellite pour...signal processing ( DSP ) chip, such as the TMS 320-C25 used here, is adequate to perform all the needed processing. Also, the complexity does not

  7. Catalog of Audiovisual Productions. Volume 2. Navy and Marine Corps Productions

    DTIC Science & Technology

    1984-06-01

    CORPS TRAINING UDERSTAND AND RECOVER THE HEALING POWER OF RTHE MODERN WORLD AISUA MART CORS THE ARLY CHRISTIAN COMUNITY. T6M MO P R 06...TRAIN14G VIDA - LIOWES. OT IWO UL AUIOVISUAL SUPPORT CENTER. 31040.1 M NiSC U.S ANP NI-1O AIR DESCRIBES VARIOUS TOXIC MATERIAL3, 351334. PREVENTIVE

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

    USDA-ARS?s Scientific Manuscript database

    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...

  9. 78 FR 68992 - Visas: Documentation of Nonimmigrants-Visa Classification; T Visa Class

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-18

    ... of a T-1 principal alien whom the Secretary of Homeland Security, in consultation with the law... retaliation as a result of the alien's escape from trafficking or cooperation with law enforcement to accompany or follow to join the principal alien. This rule amends 22 CFR 41.12 to include the T-6 visa...

  10. NCHRP report 350 test 3-11 of the modified T8 bridge rail.

    DOT National Transportation Integrated Search

    2009-04-01

    A new flexible bridge rail system, referred to as the T8 rail, was designed as a replacement for the T6 rail in high-speed applications on culverts and thin deck structures. The T8 rail failed a crash test when the breakaway posts failed the thin dec...

  11. U.S. EPA, Pesticide Product Label, , 02/14/1989

    EPA Pesticide Factsheets

    2011-04-13

    ... SIZE ~ X 3 1 3/ t 6 P5L ~'i'i~~'i~ A. .. .. J .... II LASER AlIt I IllICIt ... -- II • • t t~ II 1 •• t ,. • .J t~Z • • • • • S. LABEL • I ••••• t.t'" • • ~

  12. Determination of Natural and Depleted Uranium in Urine at the ppt Level: An Interlaboratory Analytical Exercise

    DTIC Science & Technology

    2002-10-01

    3) and NAA (4). Resume Un exercice analytique a 6t6 initi6 dans le but de determiner les procedures analytiques qui ont la capacit6 de mesurer les...but de cet exercice analytique 6tait d𔄀valuer toutes les techniques analytiques disponibles ayant la capacit6 de mesurer les rapports isotopiques

  13. Langerhans Cells in Vitiligo.

    PubMed

    Narayanan, R B; Lavania, R K; Girdhar, B K

    1986-01-01

    Langerhans cells (LC) were defined by indirect immunofluore-scence using OKT6 monoclonal antibody in the early lesions of 10 untreated vitiligo patients. The distribution and the numbers of OKT6 + epidermal LC in the lesions was similar to that observed in the normal skin. In the dermal infiltrates of some of the lesion, T6 '+ cells were visualized.

  14. 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. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  15. 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

  16. 50 CFR Appendix I to Part 37 - Legal Description of the Coastal Plain, Arctic National Wildlife Refuge, Alaska

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... mean high tide of the Beaufort Lagoon, located in section 28, T. 6 N., R. 40 E., Umiat Meridian; Thence... Meridian at the line of extreme low tide; Thence northwesterly, along the northerly boundary of the Arctic National Wildlife Refuge at the line of extreme low tide on the seaward side of all offshore bars, reefs...

  17. 50 CFR Appendix I to Part 37 - Legal Description of the Coastal Plain, Arctic National Wildlife Refuge, Alaska

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... mean high tide of the Beaufort Lagoon, located in section 28, T. 6 N., R. 40 E., Umiat Meridian; Thence... Meridian at the line of extreme low tide; Thence northwesterly, along the northerly boundary of the Arctic National Wildlife Refuge at the line of extreme low tide on the seaward side of all offshore bars, reefs...

  18. Silencing trehalose-6-phosphate synthase incapacitates adult mosquitoes by interfering with the biosynthetic pathway for flight fuel

    USDA-ARS?s Scientific Manuscript database

    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...

  19. Identification and Alteration of Global Resonance Modes in Ship Structures to Reduce Sound Radiation

    DTIC Science & Technology

    1989-05-12

    4.5 Tuning M ass Estimate ............................................................................... 38 4.6 Plate Damping and Reverberation Time ................................................... 39...4.7 W ater Tank Reverberation Time ............................................................... 40...factor (71) and reverberation time (T6), and the acoustic water tank reverberation time as a function of frequency are discussed. Additionally

  20. Comparative evaluation of cast aluminum alloys for automotive cylinder heads: Part I Microstructure evolution

    DOE PAGES

    Roy, Shibayan; Allard, Jr, Lawrence Frederick; Rodriguez, Andres; ...

    2017-03-06

    The present study stages a comparative evaluation of microstructure and associated mechanical and thermal response for common cast aluminum alloys that are used for manufacturing automotive cylinder heads. The systems considered are Al-Cu (206-T6), Al-Si-Cu (319-T7), and Al-Si (356-T6, A356-T6, and A356 + 0.5Cu-T6). The focus of the present manuscript is on the evaluation of microstructure at various length scales after aging, while the second manuscript will deal with the mechanical and thermal response of these alloys due to short-term (aging) and long-term (pre-conditioning) heat treatments. At the grain-scale, the Al-Cu alloy possessed an equiaxed microstructure as opposed to themore » dendritic structure for the Al-Si-Cu or Al-Si alloys which is related to the individual solidification conditions for these alloy systems. The composition and morphology of intermetallic precipitates within the grain and at the grain/dendritic boundary are dictated by the alloy chemistry, solidification, and heat treatment conditions. At the nanoscale, these alloys contain various metastable strengthening precipitates (GPI and θ''θ'' in Al-Cu alloy, θ'θ' in Al-Si-Cu alloy, and β'β' in Al-Si alloys) with varying size, morphology, coherency, and thermal stability.« less

  1. 78 FR 30392 - Notice of Application for Special Permits

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-22

    ... currently described in 49 CFR Sec. 180.211(c)(2)(i). (modes 1, 2, 3, 4). 15850-N Chart Industries, New 49.... transportation in commerce of certain used DOT 3AL cylinders that contain CO2, but not necessarily in an amount... cylinders manufactured from aluminum alloy 6061-T6 that are requalified every ten years rather than every...

  2. 75 FR 10811 - Notice of Application for Recordable Disclaimer of Interest in Lands, Gem County, ID

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-09

    ... Bureau of Land Management Notice of Application for Recordable Disclaimer of Interest in Lands, Gem... Rick Zamzow for a Recordable Disclaimer of Interest from the United States for islands in Gem County..., T. 6 N., R. 2 W., Boise Meridian, Gem County, Idaho, as shown on Record of Survey Instrument No...

  3. 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.…

  4. 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…

  5. 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)

  6. 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)

  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. 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)

  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. 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;…

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

    USGS Publications Warehouse

    Reeside, John B.

    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.

  12. Processing-Microstructure-Property Relationships for Cold Spray Powder Deposition of Al-Cu Alloys

    DTIC Science & Technology

    2015-06-01

    34 5. X-ray Diffraction ................................................................................ 37 B. COLD SPRAY...FIGURES Figure 1. Cold spray of aluminum/aluminum oxide to repair 7075-T6 snap ring groove. A) Damaged area , B) Areas requiring repair, and C) Cold...5Cu powder as received. ............................... 37 x Figure 25. X-ray diffraction pattern of the four as-received powders. The unknown

  13. The Search for Peace and Security: The Case of Botswana

    DTIC Science & Technology

    1994-06-01

    o" wwapw I hoar Par ,epý. schwagm t6C tie far .evusut amm seara nug ejusaft do&n saame. gaUheng sad .aammag th. dar moo edad cad okcig and .viawas the...Richard D. Irwin, 1984. Defense & Foreign Affairs Handbook. 1990-1991, International Media Corporation, 1990. du Plessis, A and Hough, M., "Civil War in

  14. 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.

  15. The effects of plasticity in adhesive fracture

    NASA Technical Reports Server (NTRS)

    Chang, M. D.; Devries, K. L.; Williams, M. L.

    1973-01-01

    An energy-balance analysis is presented for adhesive failure in end loaded cantilever beams. The analysis includes the effects of input work, stored strain energy, dissipated plastic energy, and specific adhesive surface energy. Experimental results obtained with 6061-T6 aluminum are presented as evidence for the validity of the approach.-

  16. U.S. EPA, Pesticide Product Label, TOUGH STAIN REMOVING INSTITUTIONAL COMET CLEANSER WITH CHLORINOL G, 02/10/1975

    EPA Pesticide Factsheets

    2011-04-21

    ... 1i~~~~~M~T"~C~H~~~~R~I~NO~L~~O~~~~~iil i _L~=_===7 USE COMET ~ ~ FOR THESE TOUGH ~ ... t\\t'6\\\\$ , USE COMET FOR THESE TOUGH ...

  17. First example of an ice-like water hexamer boat tape structure in a supramolecular organic host.

    PubMed

    Saha, Binoy K; Nangia, Ashwini

    2006-05-07

    A T6(2) tape of hydrogen bonded water molecules in boat cyclohexane conformation resides in the channel structure of a dibromophloroglucinol (DBPG) host; water escapes at 40-90 degrees C but is readily re-absorbed by the sponge-like apohost.

  18. Comparative evaluation of cast aluminum alloys for automotive cylinder heads: Part I Microstructure evolution

    SciTech Connect

    Roy, Shibayan; Allard, Jr, Lawrence Frederick; Rodriguez, Andres; Watkins, Thomas R.; Shyam, Amit

    2017-03-06

    The present study stages a comparative evaluation of microstructure and associated mechanical and thermal response for common cast aluminum alloys that are used for manufacturing automotive cylinder heads. The systems considered are Al-Cu (206-T6), Al-Si-Cu (319-T7), and Al-Si (356-T6, A356-T6, and A356 + 0.5Cu-T6). The focus of the present manuscript is on the evaluation of microstructure at various length scales after aging, while the second manuscript will deal with the mechanical and thermal response of these alloys due to short-term (aging) and long-term (pre-conditioning) heat treatments. At the grain-scale, the Al-Cu alloy possessed an equiaxed microstructure as opposed to the dendritic structure for the Al-Si-Cu or Al-Si alloys which is related to the individual solidification conditions for these alloy systems. The composition and morphology of intermetallic precipitates within the grain and at the grain/dendritic boundary are dictated by the alloy chemistry, solidification, and heat treatment conditions. At the nanoscale, these alloys contain various metastable strengthening precipitates (GPI and θ''θ'' in Al-Cu alloy, θ'θ' in Al-Si-Cu alloy, and β'β' in Al-Si alloys) with varying size, morphology, coherency, and thermal stability.

  19. BREAKING-STRENGTH AND ENDURANCE TESTS OF ALUMINUM TURNBUCKLES FOR AIRCRAFT.

    DTIC Science & Technology

    Breaking- strength and endurance tests were run to make possible a partial evaluation of the strength of turnbuckle bodies fabricated from 2024T6...that the ratio of average tensile strength to weight of aluminum bodies was 61 percent better than for the brass bodies. When aluminum barrels were

  20. 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

  1. 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.

  2. 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 Central

    Abou-Elkhair, R.; Ahmed, H. A.; Selim, S.

    2014-01-01

    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

  3. Humoral and cell-mediated immune responses after a booster dose of HBV vaccine in HIV-infected children, adolescents and young adults.

    PubMed

    Giacomet, Vania; Masetti, Michela; Nannini, Pilar; Forlanini, Federica; Clerici, Mario; Zuccotti, Gian Vincenzo; Trabattoni, Daria

    2018-01-01

    HBV vaccine induces protective antibodies only in 23-56% of HIV-infected children. The aim of our study is to evaluate the immunologic effects of a booster dose of HBV vaccine in HIV-infected youth. 53 young HIV-infected patients in whom HBV vaccination did not elicit protective Ab titers were enrolled. All patients were on ART with optimal immunological and viral response. All patients received a booster dose of HBV vaccine (HBVAXPRO 10 μg i.m.). HBV-specific Ab titer, viral load and CD4+ T cells were measured at baseline (T0), T1, T6 and T12 months. In a subgroup of 16 patients HBV-specific cell mediated immune responses were evaluated at baseline, at T1 and T6. The booster dose induced seroconversion in 51% of patients at T1, 57% at T6, and49% at T12; seroconversion rate was significantly correlated with CD4+T cells at T0 and to the CD4 nadir. The booster dose induced HBV-specific cell mediated immunity at T6 mainly in Responders (Rs): Effector Memory CD8+T cells, HBV-specific TNFα-, IFNγ-, granzyme secreting CD8+ T cells and IL2-secreting CD4+ T cells were significantly increased in Rs compared to T0. In Non Responders (NRs), HBV-specific IL2-secreting CD4+ T cells, Central and Effector Memory CD8+ T cells were the only parameters modified at T6. Seroconversion induced by a booster dose of vaccine correlates with the development of T cell immunological memory in HIV-infected patients who did not respond to the standard immunization. Alternate immunization schedules need to be considered in NRs.

  4. 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

  5. The HsiB1C1 (TssB-TssC) Complex of the Pseudomonas aeruginosa Type VI Secretion System Forms a Bacteriophage Tail Sheathlike Structure

    PubMed Central

    Lossi, Nadine S.; Manoli, Eleni; Förster, Andreas; Dajani, Rana; Pape, Tillmann; Freemont, Paul; Filloux, Alain

    2013-01-01

    Protein secretion systems in Gram-negative bacteria evolved into a variety of molecular nanomachines. They are related to cell envelope complexes, which are involved in assembly of surface appendages or transport of solutes. They are classified as types, the most recent addition being the type VI secretion system (T6SS). The T6SS displays similarities to bacteriophage tail, which drives DNA injection into bacteria. The Hcp protein is related to the T4 bacteriophage tail tube protein gp19, whereas VgrG proteins structurally resemble the gp27/gp5 puncturing device of the phage. The tube and spike of the phage are pushed through the bacterial envelope upon contraction of a tail sheath composed of gp18. In Vibrio cholerae it was proposed that VipA and VipB assemble into a tail sheathlike structure. Here we confirm these previous data by showing that HsiB1 and HsiC1 of the Pseudomonas aeruginosa H1-T6SS assemble into tubules resulting from stacking of cogwheel-like structures showing predominantly 12-fold symmetry. The internal diameter of the cogwheels is ∼100 Å, which is large enough to accommodate an Hcp tube whose external diameter has been reported to be 85 Å. The N-terminal 212 residues of HsiC1 are sufficient to form a stable complex with HsiB1, but the C terminus of HsiC1 is essential for the formation of the tubelike structure. Bioinformatics analysis suggests that HsiC1 displays similarities to gp18-like proteins in its C-terminal region. In conclusion, we provide further structural and mechanistic insights into the T6SS and show that a phage sheathlike structure is likely to be a conserved element across all T6SSs. PMID:23341461

  6. 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.

  7. The trehalose pathway in maize: conservation and gene regulation in response to the diurnal cycle and extended darkness

    PubMed Central

    Henry, Clémence; Bledsoe, Samuel W.; Siekman, Allison; Kollman, Alec; Waters, Brian M.; Feil, Regina; Stitt, Mark; Lagrimini, L. Mark

    2014-01-01

    Energy resources in plants are managed in continuously changing environments, such as changes occurring during the day/night cycle. Shading is an environmental disruption that decreases photosynthesis, compromises energy status, and impacts on crop productivity. The trehalose pathway plays a central but not well-defined role in maintaining energy balance. Here, we characterized the maize trehalose pathway genes and deciphered the impacts of the diurnal cycle and disruption of the day/night cycle on trehalose pathway gene expression and sugar metabolism. The maize genome encodes 14 trehalose-6-phosphate synthase (TPS) genes, 11 trehalose-6-phosphate phosphatase (TPP) genes, and one trehalase gene. Transcript abundance of most of these genes was impacted by the day/night cycle and extended dark stress, as were sucrose, hexose sugars, starch, and trehalose-6-phosphate (T6P) levels. After extended darkness, T6P levels inversely followed class II TPS and sucrose non-fermenting-related protein kinase 1 (SnRK1) target gene expression. Most significantly, T6P no longer tracked sucrose levels after extended darkness. These results showed: (i) conservation of the trehalose pathway in maize; (ii) that sucrose, hexose, starch, T6P, and TPS/TPP transcripts respond to the diurnal cycle; and(iii) that extended darkness disrupts the correlation between T6P and sucrose/hexose pools and affects SnRK1 target gene expression. A model for the role of the trehalose pathway in sensing of sucrose and energy status in maize seedlings is proposed. PMID:25271261

  8. 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 700 μg/kg doramectin; T3-treated in May (doramectin), July (4.7 mg/kg levamisole phosphate) and September (doramectin); T4-treated in May (doramectin), July (200 μg/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 28 days, 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 (120.8 kg), T3 (131.4 kg), T4 (131.2 kg) and T5 (134.4 kg). T6 was the only group with a significantly higher final weight gain (140.9 kg) 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

  9. Parasol Rib Deformity in Hypotonic Neuromuscular Scoliosis: A New Radiographical Definition and a Comparison of Short-term Treatment Outcomes With VEPTR and Growing Rods.

    PubMed

    Livingston, Kristin; Zurakowski, David; Snyder, Brian

    2015-07-01

    Retrospective review of 2 multicenter national databases, Growing Spine Study Group and Chest Wall and Spine Deformity. To derive an objective measure of parasol rib deformity from spine radiographs and to compare efficacy of rib-based (vertical expandable prosthetic titanium rib (VEPTR)) versus spine-based growing rods ("GR") instrumentation to improve parasol rib deformity and pulmonary function. Children with low tone neuromuscular scoliosis often develop collapse of the rib cage ("parasol rib deformity") that may be associated with poor pulmonary function. We compared patients with hypotonic neuromuscular scoliosis treated by VEPTR or GR with greater than 1 year follow-up. Preoperative and final spine radiographs were assessed for parasol rib collapse, spine asymmetry, and thoracic deformity. Multivariable analysis was performed on these measurements to identify the best descriptor of parasol rib deformity. Using this measurement, the ability of VEPTR versus GR to control parasol rib deformity was then compared. Assisted ventilation rating (AVR) at preoperative and final follow-up was compared between the 2 groups. Twenty-three patients treated with VEPTR (average age 6.7 years, average f/u = 3.3 years) were compared with 22 patients treated with GR (average age 7.7 years, average f/u = 2.9 years). The equation Parasol Score = (T6 convex hemithoracic width/T6 concave hemithoracic width) × (T6 thoracic width/T12 thoracic width) was the most accurate descriptor rib collapse (AUC = 0.927). Parasol Score was correlated with AVR. Parasol Score did not change over time for the patients treated with GR, but had a tendency to worsen for patients treated with VEPTR. AVR did not change significantly in either group. Spine deformity was better corrected using GR. Parasol rib deformity, measured on x-ray by the metric = (T6 width convex hemithorax/T6 width concave hemithorax)*(T6 thoracic width/T12 thoracic width), did not improve after treatment with VEPTR or GR. AVR did

  10. Thermal stress analysis of the SLAC moveable mask. Addendum 2

    SciTech Connect

    Johnson, G.L.

    1985-10-15

    X-ray beams emerging from the new SLAC electron-positron storage ring (PEP) can impinge on the walls of tangential divertor channels. A moveable mask made of 6061-T6 aluminum is installed in the channel to limit wall heating. The mask is cooled with water flowing axially at 30/sup 0/C. Beam strikes on the mask cause highly localized heating in the channel structure. Analyses were completed to determine the temperatures and thermally-induced stresses due to this heating. The current design and operating conditions should result in the entrance to the moveable mask operating at a peak temperature of 88/sup 0/C with a peak thermal stress at 19% of the yield of 6061-T6 aluminum.

  11. The Evolution of Plate and Extruded Products with High Strength and Fracture Toughness

    NASA Astrophysics Data System (ADS)

    Denzer, D. K.; Rioja, R. J.; Bray, G. H.; Venema, G. B.; Colvin, E. L.

    From the first use of 2017-T74 on the Junkers F13, improvements have been made to plate and extruded products for applications requiring the highest attainable strength and adequate fracture toughness. One such application is the upper wing of large aircraft. The progression of these product improvements achieved through the development of alloys that include 7075-(T6 & T76), 7150-(T6 & T77) and 7055-(T77 & T79) and most recently 7255-(T77 & T79) is reviewed. The most current advancements include aluminum-copper-lithium, alloy 2055 plate and extruded products that can attain strength equivalent to that of 7055-T77 with higher modulus, similar fracture toughness and improved fatigue, fatigue crack growth and corrosion performance. The achievement of these properties is explained in terms of the several alloy design principles. The highly desired and balanced characteristics make these products ideal for upper wing applications.

  12. Investigation on the modification behavior of A356.2 alloy with Yb–La composite modifier

    NASA Astrophysics Data System (ADS)

    Zhang, Shaochen; Leng, Jinfeng; Wang, Zhibin; Wang, Qi; Shao, Yuewen; Teng, Xinying

    2018-01-01

    In this work, an investigation was conducted to evaluate the influence of the Yb + La addition on the microstructures and mechanical properties of A356.2 alloy. The results show that the the grain size was refined and morphological structure of Si changed from needle-like to fine spheroidal particle by adding Yb + La. The eutectic temperature decreased from 589 °C to 581 °C and the freezing range of primary α-Al become wider after adding Yb + La. The mechanical properties showed great improvement after T6 heat treatment. The ultimate tensile strength and microhardness of the composites were increased to 279.0 MPa and 99.2 HB after T6 heat treatment which increased by 28.2% and 47.3%, respectively. The fracture mechanism was analyzed using the scanning electron microscopy and proved to be a transgranular/intergranular fracture modes.

  13. 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

  14. 3D study of intermetallics and their effect on the corrosion morphology of rheocast aluminium alloy

    SciTech Connect

    Mingo, B.; Arrabal, R.; Pardo, A.; Matykina, E.; Skeldon, P.

    2016-02-15

    In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutectic Si. These changes do not modify significantly the corrosion behaviour of the alloy. 3D SEM-Tomography clearly shows that the corrosion advances in the shape of narrow paths between closely spaced intermetallics without a major influence of eutectic Si. - Highlights: • T6.1 spheroidizes Si, strengthens the matrix and modifies the intermetallics. • Electrochemical behaviour of untreated and heat-treated alloys is similar. • 3D SEM-Tomography provides additional information on the corrosion morphology. • Corrosion advances as paths between intermetallics with little influence of Si.

  15. Universality of the Break-up Profile for the KdV Equation in the Small Dispersion Limit Using the Riemann-Hilbert Approach

    NASA Astrophysics Data System (ADS)

    Claeys, T.; Grava, T.

    2009-03-01

    We obtain an asymptotic expansion for the solution of the Cauchy problem for the Korteweg-de Vries (KdV) equation u_t+6uu_x+ɛ2u_{xxx}=0,quad u(x,t=0,ɛ)=u_0(x), for {ɛ} small, near the point of gradient catastrophe ( x c , t c ) for the solution of the dispersionless equation u t + 6 uu x = 0. The sub-leading term in this expansion is described by the smooth solution of a fourth order ODE, which is a higher order analogue to the Painlevé I equation. This is in accordance with a conjecture of Dubrovin, suggesting that this is a universal phenomenon for any Hamiltonian perturbation of a hyperbolic equation. Using the Deift/Zhou steepest descent method applied on the Riemann-Hilbert problem for the KdV equation, we are able to prove the asymptotic expansion rigorously in a double scaling limit.

  16. Enhanced stress corrosion cracking resistance and electrical conductivity of a T761 treated Al-Zn-Mg-Cu alloy thin plate

    NASA Astrophysics Data System (ADS)

    Chen, Xu; Zhai, Sudan; Gao, Di; Liu, Ye; Xu, Jing; Liu, Yang

    2018-01-01

    The stress corrosion cracking (SCC) behavior, electrical conductivity and mechanical properties of an Al-Zn-Mg-Cu alloy pre-stretched thin plate for wing skin were researched in this paper. The microstructures and SCC fracture surfaces of the alloy treated at different conditions were characterized by transmission electron microscopy, optical microscopy and scanning electron microscopy. Results indicated that with the increasing of aging temperature, the electrical conductivity and the elongation increased greatly, while the strength decreased gradually which were closely associated with the type and morphology of the precipitates. Compared with the T6 treated alloy, the SCC resistance of the T761 treated Al-Zn-Mg-Cu alloy was improved greatly. The SCC behavior of the T6 treated alloy was dominated by anodic dissolution theory, whereas the hydrogen induced cracking controlled the fracture behavior of the T761 treated alloy which was influenced by the morphology of grain boundary precipitates in this investigated alloy.

  17. 3D study of intermetallics and their effect on the corrosion morphology of rheocast aluminium alloy

    SciTech Connect

    Mingo, B.; Arrabal, R., E-mail: rarrabal@ucm.es; Pardo, A.

    2016-02-15

    In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutectic Si. These changes do not modify significantly the corrosion behaviour of the alloy. 3D SEM-Tomography clearly shows that the corrosion advances in the shape of narrow paths between closely spaced intermetallics without a major influence of eutectic Si. - Highlights: • T6.1 spheroidizes Si, strengthens the matrix and modifies the intermetallics. •more » Electrochemical behaviour of untreated and heat-treated alloys is similar. • 3D SEM-Tomography provides additional information on the corrosion morphology. • Corrosion advances as paths between intermetallics with little influence of Si.« less

  18. Receiver Optimization for Detection in Doubly Spread Communication Channels.

    DTIC Science & Technology

    1984-12-10

    then the sequence converges to some element K 6 In either Ll(RI) or L2(Rl), two elements (functions), f and g, are considered to be identifiable if...Propagation Modeling Consider a linear random time-varying system which models a WSSUS channel and has a scattering function of the form R S(T,1 ) = K 6(T...correlation using (2.4-33) and (3.2-1), i.e., R (t,t’) K ff x(t-T) 6(- ) S( -$) x*(t’-T) ej2 ( At) dTd y - = K f x(t- ) 6(c-$) x*(t’- ) ej 2 1t 0 ( At) d4

  19. 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)

  20. Antagonism toward the intestinal microbiota and its effect on Vibrio cholerae virulence.

    PubMed

    Zhao, Wenjing; Caro, Florence; Robins, William; Mekalanos, John J

    2018-01-12

    The bacterial type VI secretion system (T6SS) is a nanomachine that delivers toxic effector proteins into target cells, killing them. In mice, we found that the Vibrio cholerae T6SS attacks members of the host commensal microbiota in vivo, facilitating the pathogen's colonization of the gut. This microbial antagonistic interaction drives measurable changes in the pathogenicity of V. cholerae through enhanced intestinal colonization, expression of bacterial virulence genes, and activation of host innate immune genes. Because ablation of mouse commensals by this enteric pathogen correlated with more severe diarrheal symptoms, we conclude that antagonism toward the gut microbiota could improve the fitness of V. cholerae as a pathogen by elevating its transmission to new susceptible hosts. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  1. Type VI secretion delivers bacteriolytic effectors to target cells

    PubMed Central

    Russell, Alistair B.; Hood, Rachel D.; Bui, Nhat Khai; LeRoux, Michele; Vollmer, Waldemar; Mougous, Joseph D.

    2011-01-01

    Peptidoglycan is the major structural constituent of the bacterial cell wall, forming a meshwork outside the cytoplasmic membrane that maintains cell shape and prevents lysis. In Gram-negative bacteria, peptidoglycan is located in the periplasm, where it is protected from exogenous lytic enyzmes by the outer membrane. Here we show that the type VI secretion system (T6SS) of Pseudomonas aeruginosa breaches this barrier to deliver two effector proteins, Tse1 and Tse3, to the periplasm of recipient cells. In this compartment, the effectors hydrolyze peptidoglycan, thereby providing a fitness advantage for P. aeruginosa cells in competition with other bacteria. To protect itself from lysis by Tse1 and Tse3, P. aeruginosa utilizes specific periplasmically-localized immunity proteins. The requirement for these immunity proteins depends on intercellular self-intoxication through an active T6SS, indicating a mechanism for export whereby effectors do not access donor cell periplasm in transit. PMID:21776080

  2. 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. Themore » preliminary investigation will focus on a comparison of density, oxidation rates, water chemistry requirements, mechanical properties, thermal properties, and neutronic properties.« less

  3. Enhanced thermotolerance for ethanol fermentation of Saccharomyces cerevisiae strain by overexpression of the gene coding for trehalose-6-phosphate synthase.

    PubMed

    An, Ming-Zhe; Tang, Yue-Qin; Mitsumasu, Kanako; Liu, Ze-Shen; Shigeru, Morimura; Kenji, Kida

    2011-07-01

    The effect of overexpression of the trehalose-6-phosphate (T6P) synthase gene (TPS1) on ethanol fermentation of Saccharomyces cerevisiae has been studied at 30 and 38°C. The activity of T6P synthase and the accumulation of trehalose during ethanol fermentation were significantly improved by overexpression of TPS1, and especially at 38°C. Ethanol produced by transformants with and without TPS1 gene overexpression at 38°C was approx. 60 and 37 g/l, respectively. The fermentation efficiency of transformants with TPS1 gene overexpression at 38°C was similar to that at 30°C. The critical growth temperature was increased from 36 to 42°C by TPS1 gene overexpression. These results indicated that overexpression of the TPS1 gene had a beneficial effect on the fermentation capacity of the title yeast strain at high temperatures.

  4. Optimum outgassing cycles for aluminum and stainless steel

    NASA Technical Reports Server (NTRS)

    Garrison, R. L.

    1970-01-01

    Outgassing rates were measured for a modified 7075T6 aluminum and 304L stainless steel, for two degrees of finish, at temperatures of 285 deg F to 392 deg F, for times of 0.5 to 72 hours. The results were analyzed to determine optimum time and temperature cycles for outgassing. Optimum cycles were determined with and without the limitations of a graph. The graph related allowable time at temperature to a 5 percent or less reduction in room temperature properties of 7075T6 aluminum. For aluminum, within the limits set by reduction in mechanical properties, the optimum cycle tested was 40 hours at 285 deg F. Disregarding the limits, optimum outgassing was achieved at the highest temperatures and longest times tested, for both aluminum and stainless steel.

  5. Superomniphobic Surfaces for Military Applications: Nano- and Micro-Fabrication Methods: Year Two Report

    DTIC Science & Technology

    2011-12-01

    DEFENCE DÉFENSE & Defence R& D Canada – Atlantic Copy No. _____ Defence Research and Development Canada Recherche et développement pour la défense...of Defence R& D Canada. Alidad Amirfazli Prepared by: Alidad Amirfazli Department of Mechanical Engineering University of Alberta Edmonton, AB T6G 2G8...R& D Canada. Defence R& D Canada – Atlantic Contract Report DRDC Atlantic CR 2011-255 December 2011 Principal Author Original

  6. 76 FR 50753 - Notice of Invitation To Participate; Coal Exploration License Application OKNM 126630, Oklahoma

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-16

    ..., 301 Dinosaur Trail, Santa Fe, New Mexico; and BLM, Oklahoma Field Office, 7906 East 33rd Street Suite..., BLM New Mexico State Office, P. O. Box 27115, Santa Fe, New Mexico 87502-0115 and Vale Exploration USA... Exploration Area, LeFlore County, Oklahoma Indian Meridian T. 6 N., R. 25 E., Sec. 24, E\\1/2\\, SW\\1/4\\, and SE...

  7. Conference on the Neurobiology of Learning and Memory (2nd).

    DTIC Science & Technology

    1986-05-30

    Illinois The Rockefeller University 603 E. Daniel 1230 York Ave. Champaign, IL 61820 New York, NY 10021 Mr. Steven M. Guich Dr. Franz Hock Social Sciences...Psychology Edmonton, Alberta T6H 2B9 John Hopkins University Canada Baltimore, MD 21218 Mr. Steven Hampson Ms. Carol A. Hunt Information and Computer...Irvine, CA 92717 University of California Irvine, CA 92717 Dr. David LaBerge Cognitive Sciences Mr. Richard S. Lewis University of California Department

  8. Mechanisms of Integrin-Mediated Growth Control in Normal, Transformed, and Neoplastic Breast Cells

    DTIC Science & Technology

    1996-10-01

    Di str ibu tion a thoried t . er (proprietary iino t Oct 9 t6) exOt requef9or__ thi do C ander,_ TS. _Army_ Medical Research-anM MCMR-RM1_-S, _ Fort...cvP36 from Dr. Dean Sheppard ( University of California at San Francisco). The integrin c03031 is one extracellular matrix receptor that is expressed on

  9. Preliminary application of high-definition computed tomographic Gemstone Spectral Imaging in lung cancer.

    PubMed

    Wang, Guangli; Zhang, Chengqi; Li, Mingying; Deng, Kai; Li, Wei

    2014-01-01

    To evaluate the feasibility of multiparameter quantitative measurement lung cancer by Gemstone Spectral Imaging (GSI) high-definition computed tomography. Seventy-seven patients who were found to have a lung mass or a nodule by CT plain scan for the first time received chest contrast CT scan with GSI mode on high-definition computed tomography. The GSI viewer was used to display the spectral curve, iodine-based images, water-based images, and 101 sets of monochromatic images of a selected region of interest from the relative homogeneous area of the mass or nodule. Iodine concentration, water concentration, spectral curve slope, and CT values at 40 keV of the region of interest were measured. Finally, 68 eligible patients were divided into a pneumonia group (n = 24) and a malignant tumor group (n = 44, including squamous carcinoma, n = 29, and adenocarcinoma, n = 15). Significant differences existed in iodine concentration (t = 6.459), spectral curve slope (t = 6.276), and CT values at 40 keV (t = 6.698) between the pneumonia group and the malignant tumor group (P < 0.05), as well as between squamous carcinoma and adenocarcinoma (t = 6.494, 5.634, 6.091, respectively, P < 0.05), whereas water concentrations were found to have no difference between the 2 groups (t = 0.082, P > 0.05) and between the 2 types of malignant tumors (t = 1.234, P > 0.05). High-definition computed tomographic GSI technique might be helpful to differentiate lung cancer from lung benign lesions by providing qualitative and quantitative information.

  10. Evaluation of Expedient Surfaces for Remote Piloted Aircraft

    DTIC Science & Technology

    2017-12-01

    and CBR test (right). .................................................................................... 18 Figure 3.7. Steel plate and rubber ...1). Each panel consisted of single extruded aluminum alloy 6082-T6 core with vertical supports that spanned the length of the panels and were...3.2. Test-section layout. N 48’-4.7" 21’-7.3" NOTE: 2 ft x 8 ft metal plate placed under mats at interface. Rubber mat placed on surface 16’-0.3

  11. Experimental Investigation of Free Field and Shock-Initiated Implosion of Composite Structures

    DTIC Science & Technology

    2017-02-06

    configuration (right) Prior to set-up, all composite tube specimens are sealed using two aluminum end caps fitted with rubber 0-rings. The specimen...tube specimens were sealed using two aluminum end caps fitted with rubber 0-rings, and quick setting epoxy is applied to the seam between the end cap...continuous, micron diameter filaments. Aluminum 6061-T6 tubes were cut from commercially available extruded tubing, with an inner diameter of 61.5mm, a

  12. Characterization of Infrared Properties of Layer Semiconductors.

    DTIC Science & Technology

    1986-08-08

    in silicon were performed on silicon samples grown by the Czochralski method, which presumably have oxygen contents in the range of l07-10i atoms /cm 3...grown silicon has low oxygen content (t 1016 atoms /cm 3 ), and the detection limit if conventional differential absorption methods is - 1 10 t 6 atoms ...silicon with low oxygen content (4 lOtl atoms /cm 3 ) using an . infrared difference wavelength modulation technique. Several float-zone grown silicon

  13. Standardization Procedure for Two Instruments for Color Measurement

    DTIC Science & Technology

    1981-09-01

    4. TITLE (and Subttle) S. TYPE OF REPORT & PERIOD COVERED STANDARDIZATION PROCEDURE FOR TW6 INSTRUMENTS FOR COLOR MEASUREMEqT 6. PERFORMING ORG...neceasm mid Identify by block number) COLOR , COLOR MEASUREMENT9 CALIBRATIONS STANDARDS 20. AUS6rACT? Cmt i, am reverse obb Nf nemeeary =Wdowlty by...block umkr) A Standardizaton method was developed to check that a color measuring instrument will perform satisfactorily and that measurements made with

  14. Feasibility of laminar screw placement in the upper thoracic spine: analysis using 3-dimensional computed tomographic simulation.

    PubMed

    Padua, Mary Ruth Alfonso; Yeom, Jin S; Em, Huynh Thong; Kim, Ho-Joong; Chang, Bong-Soon; Lee, Choon-Ki; Riew, K Daniel

    2013-06-01

    Evaluation using 3-dimensional screw trajectory software and computed tomographic scans. To investigate the anatomic feasibility of laminar screw placement in the upper thoracic spine compared with pedicle screw placement. Although laminar screws have been suggested as an alternative to pedicle screws in the upper thoracic spine, previous anatomic feasibility studies have some limitations. Four types of screws were simulated from T1 to T6: unilaminar screw (US), superior bilaminar screw (SBS), inferior bilaminar screw (IBS), and pedicle screw (PS). Maximum allowable screw dimensions and the success rates of 4.5-mm screw placement were compared for each level. Laminar screw dimensions with more than 90% success rate at each level were determined for reference. Computed tomographic scans of 132 patients were analyzed. Laminar screw diameters gradually increased from T1 (4.4-5.4 mm, for each type) to T6 (4.8-6.7 mm), whereas PS diameter steeply declined from T1 (5.9 mm) to T4 (3.4 mm) and then leveled off. At T1, PS had greater success rate of 4.5-mm screw placement than laminar screws (US > IBS > SBS); at T2, US had greater success rate than IBS, followed by PS and SBS; and at T3 to T6, laminar screws (US > IBS > SBS) had greater success rate than PS in all comparisons. Except for SBS at T1, laminar screw diameters with more than 90% success rates were between 3.5 and 5.0 mm. In view of their anatomic feasibility, laminar screws can be a viable alternative to PSs in the upper thoracic spine. Particularly at T3 to T6 where the pedicle width is inherently small, the success rates of laminar screw placement were significantly and consistently higher than those of PS placement. The comparable success rates of laminar screws using commercially available screw sizes further emphasize their potential clinical use.

  15. 27 CFR 9.66 - Russian River Valley.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...; photorevised 1980; (9) Santa Rosa, California Quadrangle—Sonoma Co., 7.5 Minute Series, edition of 1954; and... continuing straight east 0.1 mile to Todd Road's intersection with Santa Rosa Avenue, a primary road that is generally parallel to U.S. Highway 101, in section 2, T6N, R8W, on the Santa Rosa map. (20) Proceed 5.8...

  16. Marine Salvage in the United States

    DTIC Science & Technology

    1982-01-01

    Martin J., The Law of Salvage, Vol. 3A for Benedict on Admiralty, Matthew Bender Co., New York, 1980, Sec. 237. 5. Baptist, C. N. T. 1979. Salvage...increase. General purpose marine equipment, such as air compressors, generators, fenders , and hoses, is available to salvors in ports throughout the eastern...Matthew Bender & Company. Sec. 268, p.T6 8. 13. "Slippage in the Levels of Awards." Fairplay (280): 5127, p. 24. 14. Jones, Capt. Colin M., USN

  17. Deployment Area Selection and Land Withdrawal/Acquisition. Chapter 4. M-X/MPS (M-X/Multiple Protective Shelter). Volume 1. Environmental Consequences to the Study Regions and Operating Base Vicinities.

    DTIC Science & Technology

    1981-10-02

    Pine , Tule (White), Wah Wah, Kobeh , Monitor , . Antelope , Garden, Jakes, and Cave. These valleys have a high density of road...Alternative State/ County PA, t-6 7 Nevada Esmeralda 138 -- Eureka 323 .. _.-L a n d e r 8 4 ...-. Lincoln 953 -- 920 Nye 1,324 -- 629 White Pine 437 -- 36... valleys or regions , could be affected. The following figures and discussion are intended to show hypothetical impacts on spring flows which could

  18. Defective Initiation of Glycosaminoglycan Synthesis due to B3GALT6 Mutations Causes a Pleiotropic Ehlers-Danlos-Syndrome-like Connective Tissue Disorder

    PubMed Central

    Malfait, Fransiska; Kariminejad, Ariana; Van Damme, Tim; Gauche, Caroline; Syx, Delfien; Merhi-Soussi, Faten; Gulberti, Sandrine; Symoens, Sofie; Vanhauwaert, Suzanne; Willaert, Andy; Bozorgmehr, Bita; Kariminejad, Mohamad Hasan; Ebrahimiadib, Nazanin; Hausser, Ingrid; Huysseune, Ann; Fournel-Gigleux, Sylvie; De Paepe, Anne

    2013-01-01

    Proteoglycans are important components of cell plasma membranes and extracellular matrices of connective tissues. They consist of glycosaminoglycan chains attached to a core protein via a tetrasaccharide linkage, whereby the addition of the third residue is catalyzed by galactosyltransferase II (β3GalT6), encoded by B3GALT6. Homozygosity mapping and candidate gene sequence analysis in three independent families, presenting a severe autosomal-recessive connective tissue disorder characterized by skin fragility, delayed wound healing, joint hyperlaxity and contractures, muscle hypotonia, intellectual disability, and a spondyloepimetaphyseal dysplasia with bone fragility and severe kyphoscoliosis, identified biallelic B3GALT6 mutations, including homozygous missense mutations in family 1 (c.619G>C [p.Asp207His]) and family 3 (c.649G>A [p.Gly217Ser]) and compound heterozygous mutations in family 2 (c.323_344del [p.Ala108Glyfs∗163], c.619G>C [p.Asp207His]). The phenotype overlaps with several recessive Ehlers-Danlos variants and spondyloepimetaphyseal dysplasia with joint hyperlaxity. Affected individuals’ fibroblasts exhibited a large decrease in ability to prime glycosaminoglycan synthesis together with impaired glycanation of the small chondroitin/dermatan sulfate proteoglycan decorin, confirming β3GalT6 loss of function. Dermal electron microcopy disclosed abnormalities in collagen fibril organization, in line with the important regulatory role of decorin in this process. A strong reduction in heparan sulfate level was also observed, indicating that β3GalT6 deficiency alters synthesis of both main types of glycosaminoglycans. In vitro wound healing assay revealed a significant delay in fibroblasts from two index individuals, pointing to a role for glycosaminoglycan defect in impaired wound repair in vivo. Our study emphasizes a crucial role for β3GalT6 in multiple major developmental and pathophysiological processes. PMID:23664118

  19. Theory for the Development of Neuron Selectivity: Orientation Specificity and Binocular Interaction in Visual Cortex.

    DTIC Science & Technology

    1981-06-05

    SELECTIVITY: ORIENTATION SPECIFICITY ,AND BINOCULAR INTERACTION IN VISUAL CORTEX (1 ) 0o Elie L. Bienenstock (2)Leon N Cooper and Paul W. Munro , 0 Center...8217: -- RTICLE) INOCULAR INTERACTION IN VISUAL COTEX ~~OGRPfTNME . . ...... .#1 ’ ’-U T6. CONTRACT OR GRANT %UMBE.W.J Elie L./Bienenstock Leon N...of the visual system, particularly of higher vertebrates, has been very extensively studied. Since the work of Hubel and Wiesel (1959, 1962) it has

  20. Location of Si vacancies and [Ti(OSi)4] and [Ti(OSi)3OH] sites in the MFI framework: a large cluster and full ab initio study.

    PubMed

    Yuan, Shuping; Si, Hongzong; Fu, Aiping; Chu, Tianshu; Tian, Fenghui; Duan, Yun-Bo; Wang, Jianguo

    2011-02-10

    Titanium silicalite-1 (TS-1) is an important catalyst for selective oxidation reactions. However, the nature and structure of the active sites and the mechanistic details of the catalytic reactions over TS-1 have not been well-understood, leaving a continuous debate on the genesis of active sites on the TS-1 surface in the literature. In this work, the location of Si vacancies and [Ti(OSi)(4)] and [Ti(OSi)(3)OH] sites in the MFI (Framework Type Code of ZSM-5 (Zeolite Socony Mobile-Five)) framework has been studied using a full ab initio method with 40T clusters with a Si:Ti molar ratio of 39:1. It was shown that the former four energetically favorable sites for Si vacancies are T6, T12, T4, and T8 and for Ti centers of [Ti(OSi)(4)] are T10, T4, T8 and T11, being partially the same sites. Whether by replacing Si vacancies or substituting the fully coordinated Si sites, the most preferential site for Ti is T10, which indicates that the insertion mechanism does not affect the favorable sites of Ti in the MFI lattice. For the defective [Ti(OSi)(3)OH] sites, it was found that the Si vacancy at T6 with a Ti at its neighboring T9 site (T6-def-T9-Ti pair) is the most energetically favorable one, followed by a T6-def-T5-Ti pair with a small energy gap. These findings are significant to elucidate the nature of the active sites and the mechanism of reactions catalyzed by TS-1 and to design the TS-1 catalyst.

  1. Mechanical and Life Properties of Sheets from Alloys of the Al - Mg - Sc System

    NASA Astrophysics Data System (ADS)

    Shvechkov, E. I.; Filatov, Yu. A.; Zakharov, V. V.

    2017-11-01

    The characteristics of strength, static crack resistance, rate of growth of fatigue cracks and cyclic endurance of annealed sheets from weldable alloys of the Al - Mg - Sc system are studied as compared to annealed sheets from alloy AMg6. The compositions of aluminum alloys with scandium (01545 and 1570S) with characteristics substantially superior to those of AMg6 and level of properties comparable to that of the base aircraft not weldable alloy 1163 in state T6 are determined.

  2. Effects of Post-Weld Heat Treatment on the Mechanical Properties of Similar- and Dissimilar-Alloy Friction Stir Welded Blanks

    NASA Astrophysics Data System (ADS)

    Zadpoor, Amir Abbas; Sinke, Jos

    2011-01-01

    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.

  3. [Effect of Femoral and Sciatic Nerve Block on Tourniquet Reaction and Postoperative Pain during Total Knee Arthroplasty].

    PubMed

    Li, Jing; Dong, Bu-huai; Wu, Xu-cai; Xu, Peng

    2015-12-01

    To observe the effect of femoral and sciatic nerve block on tourniquet reaction and postoperative pain during total knee arthroplasty (TKA). Totally 60 patients scheduled for TKA were equally divided into two groups according to the random number table (n=30):femoral nerve block (F) group and femoral and sciatic nerve block (SF) group. The changes of mean arterial pressure (MAP) and heart rate (HR) in each group were recorded at the tourniquet inflated immediately (T1),30 minutes (T2),60 minutes (T3),90 minutes (T4),loose tourniquet (T5) and post extubation (T6). The total amount of anesthetics drugs propofol and remifentanil were calculated. The pain score after extubation and the location of pain were recorded. MAP and HR in group SF were steady at T1-T6 (all P>0.05). Compared with group SF,MAP in group F were significantly increased at T2-T4 and T6 (all P<0.05),and the HR at T4 and T6 were significantly increased (all P<0.05). Compared with the group F,the total amount of propofol and remifentanil were significantly decreased in group SF (all P<0.05),and pain scores at rest and on movement were reduced (P<0.05);in addition,90% patients in group F complained of posterior popliteal pain. Femoral nerve and sciatic nerve block applied in TKA can obviously inhibit the tourniquet reaction,keep hemodynamic stability,reduce the dosage of anesthetic drug,and relieve the postoperative pain.

  4. Liquid Chromatography Electrospray Ionization Mass Spectrometric (LC-ESI-MS) and Desorption Electrospray Ionization Mass Spectrometric (DESI-MS) Identification of Chemical Warfare Agents in Consumer Products

    DTIC Science & Technology

    2007-06-01

    criminal prosecution or to insure the safety of consumer products. Future Plans: The reported methodologies will be a valuable addition to the in...canadienne d’inspection des aliments , ThermoFisher et National Research Council a 6t6 financde pour Ia mise au point et l𔄀valuation de la spectrom...consommation, qu’un agent de guerre chimique a 6t utilis6. Plans futurs : Les mdthodologies documentdes seront un ajout important aux m~thodes intemnes

  5. A Review of Australian and New Zealand Investigations on Aeronautical Fatigue During the Period April 2005 to March 2007

    DTIC Science & Technology

    2007-04-01

    8-53 8.4.3 Initiation and Growth of Fatigue Cracks from Pits in Pre-corroded...include inter-metallic particles; etch pits and material folds due to bead shot peening. The fatigue life of any given metallic structure...of 7075-T6 have been fatigue tested using spectrum loading in corroded and uncorroded states. The shape and morphology of the corrosion pits were

  6. Effective Management of Hexavalent Chromium (Cr+6) in DoD Organic and Inorganic Coatings Operations

    DTIC Science & Technology

    2014-11-19

    stropki@battelle.org 614-424-5414 ASETSDefense 2014 November 19, 2014 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting...19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98...Determine impacts of HCR on select aerospace substrates - ferrous (1020 CS and 4340 HSS ), non-ferrous (Al 2024-T3, Al7075-T6, and Mg AZ31B-H24

  7. Seven-Color Photometry and Classification of Stars in the Direction of Open Cluster M29 (NGC 6913) in Cygnus

    DTIC Science & Technology

    2013-01-01

    Observatory, T6ravere, Estonia -~-~,-,~_A. G. Davis Philip, Institute for Space Observations, Schenectady, New York, , ~S.A. ,’ I. Platais, Johns Hopkins...we undertook CCD photometry of the area in the Viln-ius system (StraiZys 1992) with three telescopes of different diameters and field sizes. 2...OBSERVATIONS, DATA REDUCTION AND SPECTRAL TYPES The observational material was obtained with CCD cameras on three different telescopes : the wide

  8. [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.

  9. Project Work Assignment | Sustainable Stormwater Funding Project

    EPA Pesticide Factsheets

    2010-11-30

    ... J'l.wroprl 8OOljJf!'l fOI 8..... n """ Nwo I.1n DCN N. e_ e_ prog~;"':x~~ment ObI~~Cl~·· unt I ICents) SI:~~~O:t COSI~~od. Max6 Mo•• Ma:t6 ,,",7 1 ...

  10. 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.

  11. 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.

  12. Conference Proceedings on Smokeless Propellants Held in Florence, Italy on 12-13 September 1985

    DTIC Science & Technology

    1986-01-01

    ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT (ORGANISATION DU TRAITE DE L -ATLANTIQUE NORD) AGARD Conference Proceedings No.391 SMOKELESS...Aerospace Engineering Pasadena, California 91125. US Kluyverwel; 1, 2629 HS D#elft, Netherlands M.B.Zcller Soci6t6 Nationale des Poudres ct flxplosifs...9 BURNING STABILITY OF DOUBLE BASE PRIOPELLANTS by L . De Luca, C.Zanotti, G.Riva, R.IDondk, A.Volpi, C.Grinialdl and G.Colointia 10 ENERGETIC BINDERS

  13. Mass Estimation and Its Applications

    DTIC Science & Technology

    2012-02-23

    w.r.t. the number of dimensions of the mass space, t. 4.2 Regression In this experiment, we compare SVR′ with SVR— support vector regression [16] that...generative classifiers; whereas, Artificial Neural Networks (ANN), Linear Logistic Regression (LLR), Support Vector Machines (SVM) are examples of...mass space, t. 6.2 Regression In this experiment, we compare SVR′′ and SVR′ with SVR— support vector regression [23] that employs the mapped mass space

  14. Environmental Assessment for Management of South End of Runway Wetlands, Moody AFB, Georgia

    DTIC Science & Technology

    2010-11-01

    Landing Red-winged blackbird 11 March 2004 T-6 300 feet Little blue heron 14 July 2004 Unknown 0 feet Eastern kingbird 7 November 2004 HH-60...observed on the site, along with small flocks of medium-sized wading birds (e.g., white ibis and little blue heron) (MAFB 2001). Currently, the...Management Alternative 5 involves mainly vegetation management, with very little excavation and construction involved. As such, Alternative 5 would have

  15. Combined spinal-epidural anesthesia with hypobaric ropivacaine in sitting position significantly increases the incidence of hypotension in parturients undergoing cesarean section.

    PubMed

    Xu, Zhendong; Shen, Fuyi; Zhang, Yueqi; Tao, Yiyi; Chen, Xiubing; Liu, Zhiqiang

    2017-04-01

    Maternal position during induction of combined spinal-epidural anesthesia (CSEA) may affect hemodynamics and block characteristics. This study aimed to assess whether the sitting position is more likely to induce hypotension and higher block level than the lateral position in CSEA with hypobaric ropivacaine. Ninety American Society of Anesthesiologists physical status I and II parturients undergoing elective cesarean section were randomized into three groups: the sitting, left-lateral, and right-lateral position groups. The L3-4 interspace was selected as the puncture site, and subarachnoid injection of 2.5 mL 0.5% hypobaric ropivacaine was administered. After the epidural catheter was inserted and fixed, the patient's position was changed to the left-leaning supine position. The blood pressure was measured once every 1 min followed by once every 3 min after the delivery. The sensory block level was regularly measured. A total of 88 parturients were included in this study. The incidences of hypotension in the sitting, left-lateral, and right-lateral position groups were 72%, 38%, and 40%, respectively, P = 0.012. Incidence and total dose of the phenylephrine supplement in the sitting position group were significantly higher than in the other two groups. The sitting position group showed a significantly higher block level (T4 [T3, T4]) as compared to the left-lateral (T6 [T5, T6]) and right-lateral position groups (T6 [T4, T6]), P < 0.01. The Apgar scores of neonates at 1 min and 5 min, and the pH values of the umbilical arterial and venous blood were similar among the three groups. As compared to the lateral positions, CSEA with hypobaric ropivacaine in the sitting position is more likely to cause hypotension and excessively high block level. © 2016 Japan Society of Obstetrics and Gynecology.

  16. Characterizing regional correlation, laterality and symmetry of amyloid deposition in mild cognitive impairment and Alzheimer's disease with Pittsburgh Compound B.

    PubMed

    Raji, Cyrus A; Becker, James T; Tsopelas, Nicholas D; Price, Julie C; Mathis, Chester A; Saxton, Judith A; Lopresti, Brian J; Hoge, Jessica A; Ziolko, Scott K; DeKosky, Steven T; Klunk, William E

    2008-07-30

    We evaluated the region-to-region correlation, laterality and asymmetry of amyloid deposition in subjects with mild cognitive impairment (MCI) or Alzheimer's disease (AD) using the amyloid tracer, Pittsburgh Compound B (PiB). Seventeen subjects, including 7 with MCI (MMSE 26.7+/-2.4) and 10 with AD (MMSE of 24.8+/-2.7) underwent PiB imaging. Measures of laterality (i.e., group-wise predilection for right or left) and asymmetry (i.e., group-wise predilection for unequal PiB retention between the two hemispheres) were calculated for 17 Regions of Interest (ROIs). Regional correlations were calculated along with within-group and between-groups statistical analyses of laterality and asymmetry metrics. The median correlation between PiB retention across all pairs of ROIs was 0.65, with highest correlations found in areas of highest PiB retention (r=0.74). Overall, PiB retention was symmetric bilaterally, but there was PiB laterality in MCI in dorsal frontal cortex [(t(6)=3.05, p=0.02, L>R] and sensory-motor area [t(6)=3.10, p=0.02, L>R] and in AD in the occipital pole (t(9)=-2.63, p=0.03, R>L). The most significant asymmetries in PiB retention were found in sub-cortical white matter (t(6)=3.99, p=0.01) and middle precuneus [(t(6)=3.57, p=0.01] in MCI, and in lateral temporal cortex (t(9)=3.02, p=0.01) and anterior ventral striatum [t(9)=2.37, p=0.04] in AD. No group differences (AD versus MCI) were detected in laterality [F (1, 15)=0.15, p=0.7] or asymmetry [F (1, 15)=0.7, p=0.42].

  17. NOVA-2S Correlation with KC-135A Fuselage Shock Tube Test Results

    DTIC Science & Technology

    1982-11-01

    the skin of this upper lobe compartment panel is 0.064-in 7075-T6 aluminum. The reference surface of the panel is set in NOVA-2LTS at the midsurface ...direction with a radius of 71.968 in to the midsurface of the skin and a subtended angle of 215.9’. The Y boundaries (circular edges) are assumed to be

  18. Camouflage effects following resin infiltration of postorthodontic white-spot lesions in vivo: One-year follow-up.

    PubMed

    Eckstein, Amely; Helms, Hans-Joachim; Knösel, Michael

    2015-05-01

    To assess camouflage effects by concealment of postorthodontic white-spot lesions (WSLs) to sound adjacent enamel (SAE) achieved over 12 months with resin infiltration (Icon, DMG, Hamburg, Germany). Twenty subjects (trial teeth nteeth = 111) who had received resin infiltration treatment of noncavitated postorthodontic WSLs were contacted for a 1-year follow-up assessment of CIE-L*a*b* colors (T12). Color and lightness (CIE-L*a*b*) data for WSLs and SAE were compared to baseline data assessed before infiltration (T0) and those assessed after 6 months (T6), using a spectrophotometer. The target parameter was the difference between the summarized color and lightness values (ΔEWSL/SAE). Intergroup (WSL, SAE) and intertime comparisons (T0 vs T6, T12) were performed using paired t-tests at a significance level of α = 5%. Nine subjects (trial teeth nteeth = 49; male/female ratio 5/4; age range 13-19 years) were available at T12. After the highly significant reduction of ΔEWSL/SAE discrepancies between T0 and T6, analysis of 12-month records revealed color and lightness discrepancy of WSL vs SAE that was significantly decreased compared with baseline, indicating an assimilation of WSL color to SAE appearance after infiltration, while an additional reduction of discrepancies between T6 and T12 was not significant. As color and lightness characteristics of the Icon infiltrant as well as the esthetic camouflage effects achieved by WSL infiltration were not altered significantly or clinically relevant after 12 months, the method of resin infiltration can be recommended for an enduring esthetic improvement of postorthodontic WSL.

  19. A Posteriori Quantification of Rate-Controlling Effects from High-Intensity Turbulence-Flame Interactions Using 4D Measurements

    DTIC Science & Technology

    2016-11-22

    DISTRIBUTION A: Distribution approved for public release. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This project addressed variations in the chemical reaction rate as...this to the local thermo- chemical structure. These objectives were achieved by simultaneous application of various high-speed laser-based...Aerospace Studies University of Toronto Toronto, ON, Canada, M3H 5T6 July 6, 2016 1 Overview This project addressed variations in the chemical reaction rate

  20. Innovative Approaches to Flaw-Tolerant Design and Certification of Airframe Components. Report on NACA Data- Task 6

    DTIC Science & Technology

    2017-10-16

    of 24S-T3, 75S-T6 and SAE 4130, the calibration procedure to obtain the Beta-HSV curves for each material, and the prediction of fatigue life based...Fatigue, Stress Life , Life Prediction, Highly Stressed Volume, High Cycle Fatigue, Model Calibration, NACA 16. SECURITY CLASSIFICATION OF: 17...scheduled maintenance action by enabling prediction of remaining life . One of the unique aspects of the approach is the development of a family of

  1. Aluminum Alloy 7050 Extrusions.

    DTIC Science & Technology

    1977-03-01

    Alloy 7050 is a recently introduced Al - Zn -Mg- Cu -Zr alloy developed at Alcoa Laboratories under partial...corrosion of Al - Zn -Mg- Cu alloy products increase with aging 22 time beyond peak strength at temperatures above about 300oF has been established for... in an Al - Cu -Mg alloy and in Alclad 7075-T6 sheet. It can be seen that the effect of water 251 ■ ,.■«? ■•■-•-.. ■. _-— - 2

  2. The Effect of Abrasive Blasting on the Fatigue and Corrosion of an Aluminium-Copper Alloy

    DTIC Science & Technology

    1984-08-01

    examine the effects of abrasive blasting on corrosion have demonstrated that the corrosion rate and type of pitting attack on 2014-T6 aluminium alloy...effects which prior corrosion casn have an thu fatigue behaviour of L93 aluminium alloy. 8 hours exposure to neutral salt Log generates sufficient...depth 120 M. Several investigations have been made into the effects of corrosion on the fatigue of aluminium alloys. Weston and Wilson9 for exapla

  3. Positron Annihilation Gamma Ray Lineshape Studies of Defects in Solids.

    DTIC Science & Technology

    1980-06-24

    Unfortunately, slight surface orientation tallographic orientations using the Laue back reflec- changes precluded effective etching of the crystals...caused by irradiation with neutrons and electrons, fatigue, quenching, and plastic deformation. The present note describes positron effects noted for the... diffraction . The 7075 alloy was in the T6 condition which signifies solution heat treatment and artificial aging to maximum hardness. The 2024 alloy was

  4. M-QAM Modem Verification

    DTIC Science & Technology

    1982-02-01

    objc.t.6, intettigene~e da~ta cottection and handt~ng, in~o~matio.-on Ay6yem technotogy, kono,6pheA.Ze pt’opagat4on, .6otd sta~te. scenc ~e., rfl4c~4omave phy4.6ia and etect’wniLc %etiabit%, rnaAntainabitity and compa~tibZLZty.

  5. Guidance and Control Technology for Highly Integrated Systems.

    DTIC Science & Technology

    1981-02-08

    permettre une grande libert en cap au-dessus de la zone de recalage. L’expos6 r~sume ensuite les principales carac - t6ristiques d’utilisation...bon mod’ale des erreurs de l’inertie, des carac - t~ristiques tr’aa basse fr~quence de 1𔄀volution de ces erreurs, et de la grande pr6ci- sion des

  6. Establishment of a VISAR Measurement System for Material Model Validation in DSTO

    DTIC Science & Technology

    2013-02-01

    thermodynamic consistency of the model. Current choices of constants in CTH for the SGL model for many materials (including steel and aluminium 6061-T6 alloy ...and accuracy of the system installation. The effects associated with high strain rate material response and set- up projectile-target misalignment...are analysed with the CTH code [5] using the rate sensitive model recently implemented in CTH [6]. Comparison of the simulation results with the test

  7. Environmental Fate of Hydrazines

    DTIC Science & Technology

    1989-12-01

    gas chromatography (GC). Over the 4-hour test period, the oxygen concentration was found to increase at 0.13 percent per hour. Although rigorous...heterogeneous catalysis. In particular, a gas chromatography technique (originally developed by Hall and Emmett, Reference 23) using microreactors permits... chromatography packing in narrow-bore e tubing (1.25 grams)T-6 chromnatography packing in wide-bore tubbnS (?.4 grams) c. Other Hydraziaes B;nk experiments using

  8. Effects of dietary postbiotic and inulin on growth performance, IGF1 and GHR mRNA expression, faecal microbiota and volatile fatty acids in broilers.

    PubMed

    Kareem, Karwan Yaseen; Loh, Teck Chwen; Foo, Hooi Ling; Akit, Henny; Samsudin, Anjas Asmara

    2016-08-05

    Postbiotics (metabolic products by lactic acid bacteria) and prebiotics have been established as substitute to antibiotics in order to enhance immunity and growth performance in broiler chickens. Nonetheless, insufficient information is available on the effects of postbiotics and prebiotics combination on growth performance, faecal microbiota, pH and volatile fatty acids (VFA), as well as liver insulin like growth factor 1 (IGF1) and growth hormone receptor (GHR) mRNA expressions in broiler chickens. The aim of this experiment was to evaluate the effects of different types of postbiotics with different levels of prebiotic (inulin) on broiler for those parameters. The results showed that birds fed T3: (0.3 % RI11 + 0.8 % Inulin), T4: (0.3 % RI11 + 1.0 % Inulin), and T6: (0.3 % RG14+ 1.0 % Inulin) had higher (p < 0.05) final body weight (BW) and total weight gain (WG) than other treatments. Birds fed T3 had lower feed conversion ratio (FCR) which was significantly different from those fed with negative control diet but was similar to other treatments. Postbiotic and inulin increased (p < 0.05) faecal lactic acid bacteria (LAB) and reduced (p < 0.05) Enterobacteriaceae count. Birds fed T4 and T6 had higher faecal acetic acid and propionic acid respectively, and both had higher total VFA and lactic acid bacteria but lower pH and Enterobacteriaceae (ENT) counts compared to other treatments. The liver of birds fed T4 and T6 had higher IGF1 expression compared to other treatments while T6 had higher GHR mRNA expression compared to other treatments. Results indicate that the addition of postbiotics and inulin combinations had beneficial effects on total BW, feed efficiency, mucosa architecture and IGF1 and GHR mRNA expression in broiler chickens.

  9. Recent Airpower Approaches to Counterinsurgency Operations

    DTIC Science & Technology

    2015-04-01

    Force ( PAF ) proved to be invaluable in enabling government forces to effectively combat the Huks. The PAF received significant American military...aid in the form of T-6, BT-13, P-51D and various transport aircraft that they employed in a variety of missions. The PAF provided CAS, intelligence...beginning of the rebellion in 1946 until the PAF reached peak efficiency in 1952.15 Throughout the insurgency, PAF assets developed tactics to support

  10. Randomized Evaluation of the Effectiveness of a Structured Educational Program for Patients With Essential Hypertension.

    PubMed

    Perl, Sabine; Niederl, Ella; Kos, Cornelia; Mrak, Peter; Ederer, Herbert; Rakovac, Ivo; Beck, Peter; Kraler, Elisabeth; Stoff, Ingrid; Klima, Gert; Pieske, Burkert M; Pieber, Thomas R; Zweiker, Robert

    2016-07-01

    Adherence to medication and lifestyle interventions are essential keys for the management of hypertension. In this respect, a structured educational program for hypertensive patients has got remarkable merits (herz.leben). In order to determine the isolated effect of participation in the educational program, neglecting the possible impact of more intense care, this prospective multicenter randomized controlled study was designed (NCT00453037). A total of 256 patients in 13 centers were enrolled and randomly assigned to 2 groups (G). G-I (n = 137) underwent the educational program immediately (T-0), G-II (n = 119) after 6 months (T-6). Follow-up visits were done after 6 (T-6) and 12 (T-12) months. Primary endpoint was a difference in office blood pressure (BP) at T-6, when only G-I had undergone the educational program. Patients' baseline characteristics were comparable. At T-6, systolic office and home BP were significantly lower in G-I compared to G-II: office BP systolic 139 (134-150) mm Hg vs. 150 (135-165) mm Hg (P < 0.01); diastolic 80 (76-85) mm Hg vs. 84 (75-90) mm Hg (ns); home BP systolic 133 (130-140) mm Hg vs. 142 (132-150) mm Hg (P < 0.01); diastolic 80 (75-85) mm Hg vs. 80 (76-89) mm Hg (ns)). At T-12, when all patients had undergone the educational program differences in BP disappeared. The results of this multicenter randomized controlled study provide significant evidence for benefit by participation in a structured educational program. Positive effects seem to be mediated by better adherence and life style changes due to higher levels of information and patient empowerment. Therefore, educational strategies should be considered as standard of care for hypertensive patients. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. 40 CFR 415.82 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415.82 Effluent limitations guidelines... available (BPT): Subpart H—Hydrofluoric Acid Pollutant or pollutant property BPT effluent limitations... product TSS 11.0 5.3 Fluoride (T) 6.1 2.9 Nickel (T) k0.036 0.011 Zinc (T) 0.12 0.036 pH (1) (1) 1 Within...

  12. 40 CFR 415.82 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415.82 Effluent limitations guidelines... available (BPT): Subpart H—Hydrofluoric Acid Pollutant or pollutant property BPT effluent limitations... product TSS 11.0 5.3 Fluoride (T) 6.1 2.9 Nickel (T) k0.036 0.011 Zinc (T) 0.12 0.036 pH (1) (1) 1 Within...

  13. 40 CFR 415.82 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415.82 Effluent limitations guidelines... available (BPT): Subpart H—Hydrofluoric Acid Pollutant or pollutant property BPT effluent limitations... product TSS 11.0 5.3 Fluoride (T) 6.1 2.9 Nickel (T) k0.036 0.011 Zinc (T) 0.12 0.036 pH (1) (1) 1 Within...

  14. 40 CFR 415.82 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415.82 Effluent limitations guidelines... available (BPT): Subpart H—Hydrofluoric Acid Pollutant or pollutant property BPT effluent limitations... product TSS 11.0 5.3 Fluoride (T) 6.1 2.9 Nickel (T) k0.036 0.011 Zinc (T) 0.12 0.036 pH (1) (1) 1 Within...

  15. 40 CFR 415.82 - Effluent limitations guidelines representing the degree of effluent reduction attainable by the...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SOURCE CATEGORY Hydrofluoric Acid Production Subcategory § 415.82 Effluent limitations guidelines... available (BPT): Subpart H—Hydrofluoric Acid Pollutant or pollutant property BPT effluent limitations... product TSS 11.0 5.3 Fluoride (T) 6.1 2.9 Nickel (T) k0.036 0.011 Zinc (T) 0.12 0.036 pH (1) (1) 1 Within...

  16. Human Error in Merchant Marine Safety.

    DTIC Science & Technology

    1976-06-01

    L - Human Error in SMerchant Marine Safetv D jfC AU 18 19T6 Maritime Transportation Research Board 4 Commission on Sociotechnical Systems- S- -1 I...Transportation Research Board National Research Council 2101 Constitution Avwnue N.W. Washington, D. C. 20418 Phone: (202) 389-6663 ii! ABSTRACT This... constitute 42% of all steamships and motorships. Large tankers, with their reduced maneuverability and greater cost associated with their. casualties, are

  17. Arm Cycling Combined with Passive Leg Cycling Enhances VO2peakin Persons with Spinal Cord Injury Above the Sixth Thoracic Vertebra.

    PubMed

    Tørhaug, Tom; Brurok, Berit; Hoff, Jan; Helgerud, Jan; Leivseth, Gunnar

    2018-01-01

    Objective : To test whether passive leg cycling (PLC) during arm cycling ergometry (ACE) affects peak oxygen uptake (VO 2peak ) differently in individuals with spinal cord injury (SCI) at/above the 6th thoracic vertebra (T6) and below T6. Methods: We conducted a cross-sectional study, analyzed by univariate and multivariate regression models. Between- and within-group differences were examined during (a) ACE only, (b) ACE combined with PLC (ACE-PLC), and (c) ACE combined with functional electrical stimulation cycling (FES hybrid). Fifteen SCI subjects were recruited and grouped according to injury level: at/above T6 (SCI-high, n = 8) or below T6 (SCI-low, n = 7). VO 2peak tests during ACE only, ACE-PLC, and FES hybrid were performed in random order on separate days. Results : In the SCI-high group, mean ( SD ) VO 2peak was 19% higher during ACE-PLC than during ACE only [21.0 (3.8) vs 17.7 (5.0) mL·kg -1 ·min -1 ; p = .002], while VO 2peak during FES hybrid cycling was 16% higher than during ACE-PLC [24.4 (4.1) mL·kg -1 ·min -1 ; p = .001]. No significant differences among exercise modalities were found for the SCI-low group. Conclusion : Additional training modalities (eg, PLC) during ACE facilitate exercise in SCI-high individuals, but not to the level of the FES hybrid method. Conversely, additional training modalities may not increase training load in SCI-low individuals.

  18. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... viticultural area are two U.S.G.S. maps, in the scale 1:100,000. They are entitled: (1) “Walla Walla... intersects with an unnamed light duty road approximately 250 feet east of U.S. Highway 12 in Minnick... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near an...

  19. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... viticultural area are two U.S.G.S. maps, in the scale 1:100,000. They are entitled: (1) “Walla Walla... intersects with an unnamed light duty road approximately 250 feet east of U.S. Highway 12 in Minnick... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near an...

  20. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... viticultural area are two U.S.G.S. maps, in the scale 1:100,000. They are entitled: (1) “Walla Walla... intersects with an unnamed light duty road approximately 250 feet east of U.S. Highway 12 in Minnick... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near an...

  1. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... viticultural area are two U.S.G.S. maps, in the scale 1:100,000. They are entitled: (1) “Walla Walla... intersects with an unnamed light duty road approximately 250 feet east of U.S. Highway 12 in Minnick... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near an...

  2. 27 CFR 9.91 - Walla Walla Valley.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... viticultural area are two U.S.G.S. maps, in the scale 1:100,000. They are entitled: (1) “Walla Walla... intersects with an unnamed light duty road approximately 250 feet east of U.S. Highway 12 in Minnick... moving onto the Pendleton U.S.G.S. map, where it meets the 450 m contour line in T6N/R32E, near an...

  3. Effects of nanocalcium carbonate on egg production performance and plasma calcium of laying hens.

    PubMed

    Ganjigohari, S; Ziaei, N; Ramzani Ghara, A; Tasharrofi, S

    2018-02-01

    This experiment was conducted to evaluate the effects of nanocalcium carbonate (NCC) instead of calcium carbonate (CC) on egg production, egg weight, egg mass, FCR, blood calcium and egg quality characteristics in laying hens. A total of 120 laying hens were used in a 10-weeks trial, from week 23 to 33 of age. Laying hens were randomly assigned to six treatments with four replications, five hens each. The experimental treatments involved replacing 50% of the CC in the diet by decreasing amounts of NCC and were T1 Basal diet (BD) with 8.06% CC; T2 (6.045% of CC as a negative control); T3 (4.03% of CC replaced by 2.015% NCC); T4 (4.03% of CC replaced by 1.01% NCC); T5 (4.03% of CC replaced by 0.252% NCC) and T6 (4.03 of CC replaced with 0.126%NCC).Egg weight was unaffected by dietary treatments (p > .05). However, the egg production percentage and egg mass in T6 were less than that of other treatments (p < .05). The laying hens in the control group had the best average feed conversion ratio (p < .05). Also, the lowest concentration of calcium in hens' blood was recorded for birds fed T6 (p < .05). The best egg shell quality (relative egg shell weight and egg shell weight/surface) was observed in T1 (p < .05).Collectively, our results demonstrated that NCC could replace CC at a lower inclusion level but extreme reduction of calcium concentration in diets (to 1.43% Ca in the T6 group) reduced production performance, egg quality characteristics, Tibia thickness and blood calcium of laying hens. © 2017 Blackwell Verlag GmbH.

  4. The Examination of the Aluminum Alloy 7017 as a Replacement for the Aluminum Alloy 7039 in Lightweight Armor Systems

    DTIC Science & Technology

    2016-07-01

    ABSTRACT The aluminum alloy ( AA ) 7039 has been recognized as a serviceable armor plate alloy for years. However, the inherent stress corrosion...aluminum alloy ( AA ) 7039 has been recognized as a weldable armor plate alloy for many years,1 the inherent stress corrosion cracking susceptibility...Walter Contract Number Test Facility: EF110 G Target Description: AA 7017-T6 Plate ID #495905 Heat ID #2G2 Penetrator: .50 CAL AP M2

  5. Effects of Post-Weld Heat Treatment on the Mechanical Properties of Similar- and Dissimilar-Alloy Friction Stir Welded Blanks

    SciTech Connect

    Zadpoor, Amir Abbas; Faculty of Aerospace Engineering, Delft University of Technology; 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 aluminummore » 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.« less

  6. International Symposium on Gas Kinetics (9th) Held in Bordeaux, France on 20-25 July 1986. Abstracts

    DTIC Science & Technology

    1986-07-25

    versidad a Distancia, Ciudad Universitaria , 28040 Madrid . 3.M. Fiquera, J. Medina and 3.C. Rodriguez, Int de Quimica Fi sica "Rocasolano", CSIC, Serrano...Society of Chemistry of Great Britain and the Division de Chimie-Physique de la Soci~t6 Frangaise de Chimie. INTERNATIONAL ORGANIS ING COMMITTEE F...Society of Chemistry of Great Britain and the Division de Chimie-Physique de la Socidt6 Frangaise de Chimie. CONFERENCE PROGRAMME Registration and

  7. A 52 Kilodalton Protein Vaccine Candidate for Francisella tularensis

    DTIC Science & Technology

    2004-12-01

    December 2004 Canadli Abstract For identifying Francisella tularensis vaccine candidates, mice were first vaccinated with Brucella abortus O-polysaccharide...tularensis, des souris ont d’abord 6t6 vaccindes avec le vaccin O-polysaccharide Brucella abortus (OPS). Ces animaux ont requ 10 DL 50 de la souche... Brucella abortus) to protect mice from a different but cross- reactive threat agent (e.g. Francisella tularensis live vaccine strain). These vaccinated

  8. Friendly Fire: The Price of War

    DTIC Science & Technology

    1993-04-08

    USMC; Captain M. J. Perro , USA; Q V 4v Captain S. J. Wood, USMC 14 Command and Control Systems Course Communication Officer’s School 2085 Morrell Avenue...USMC Captain M. J. Perro , USA Captain S. J. Wood, USMC April 8, 1993 _ 4-1 • •• 93 11 1 t6• S... .. ..... . . . Il II0- . . . V, FRIENDLY FIRE: THE

  9. 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.

  10. Effect of gut bacterial isolates fromApis mellifera jemeniticaonPaenibacillus larvaeinfected bee larvae.

    PubMed

    Al-Ghamdi, Ahmad; Ali Khan, Khalid; Javed Ansari, Mohammad; Almasaudi, Saad B; Al-Kahtani, Saad

    2018-02-01

    The probiotic effects of seven newly isolated gut bacteria, from the indegenous honey bees of Saudi Arabia were investigated. In vivo bioassays were used to investigate the effects of each gut bacterium namely, Fructobacillus fructosus (T1), Proteus mirabilis (T2), Bacillus licheniformis (T3), Lactobacillus kunkeei (T4), Bacillus subtilis (T5), Enterobacter kobei (T6), and Morganella morganii (T7) on mortality percentage of honey bee larvae infected with P. larvae spores along with negative control (normal diet) and positive control (normal diet spiked with P. larvae spores). Addition of gut bacteria to the normal diet significantly reduced the mortality percentage of the treated groups. Mortality percentage in all treated groups ranged from 56.67% up to 86.67%. T6 treated group exhibited the highest mortality (86.67%), whereas T4 group showed the lowest mortality (56.67%). Among the seven gut bacterial treatments, T4 and T3 decreased the mortality 56.67% and 66.67%, respectively, whereas, for T2, T6, and T7 the mortality percentage was equal to that of the positive control (86.67%). Mortality percentages in infected larval groups treated with T1, and T5 were 78.33% and 73.33% respectively. Most of the mortality occurred in the treated larvae during days 2 and 3. Treatments T3 and T4 treatments showed positive effects and reduced mortality.

  11. 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.

  12. 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

  13. A genomic island in Vibrio cholerae with VPI-1 site-specific recombination characteristics contains CRISPR-Cas and type VI secretion modules

    PubMed Central

    Labbate, Maurizio; Orata, Fabini D.; Petty, Nicola K.; Jayatilleke, Nathasha D.; King, William L.; Kirchberger, Paul C.; Allen, Chris; Mann, Gulay; Mutreja, Ankur; Thomson, Nicholas R.; Boucher, Yan; Charles, Ian G.

    2016-01-01

    Cholera is a devastating diarrhoeal disease caused by certain strains of serogroup O1/O139 Vibrio cholerae. Mobile genetic elements such as genomic islands (GIs) have been pivotal in the evolution of O1/O139 V. cholerae. Perhaps the most important GI involved in cholera disease is the V. cholerae pathogenicity island 1 (VPI-1). This GI contains the toxin-coregulated pilus (TCP) gene cluster that is necessary for colonization of the human intestine as well as being the receptor for infection by the cholera-toxin bearing CTX phage. In this study, we report a GI (designated GIVchS12) from a non-O1/O139 strain of V. cholerae that is present in the same chromosomal location as VPI-1, contains an integrase gene with 94% nucleotide and 100% protein identity to the VPI-1 integrase, and attachment (att) sites 100% identical to those found in VPI-1. However, instead of TCP and the other accessory genes present in VPI-1, GIVchS12 contains a CRISPR-Cas element and a type VI secretion system (T6SS). GIs similar to GIVchS12 were identified in other V. cholerae genomes, also containing CRISPR-Cas elements and/or T6SS’s. This study highlights the diversity of GIs circulating in natural V. cholerae populations and identifies GIs with VPI-1 recombination characteristics as a propagator of CRISPR-Cas and T6SS modules. PMID:27845364

  14. A genomic island in Vibrio cholerae with VPI-1 site-specific recombination characteristics contains CRISPR-Cas and type VI secretion modules.

    PubMed

    Labbate, Maurizio; Orata, Fabini D; Petty, Nicola K; Jayatilleke, Nathasha D; King, William L; Kirchberger, Paul C; Allen, Chris; Mann, Gulay; Mutreja, Ankur; Thomson, Nicholas R; Boucher, Yan; Charles, Ian G

    2016-11-15

    Cholera is a devastating diarrhoeal disease caused by certain strains of serogroup O1/O139 Vibrio cholerae. Mobile genetic elements such as genomic islands (GIs) have been pivotal in the evolution of O1/O139 V. cholerae. Perhaps the most important GI involved in cholera disease is the V. cholerae pathogenicity island 1 (VPI-1). This GI contains the toxin-coregulated pilus (TCP) gene cluster that is necessary for colonization of the human intestine as well as being the receptor for infection by the cholera-toxin bearing CTX phage. In this study, we report a GI (designated GIVchS12) from a non-O1/O139 strain of V. cholerae that is present in the same chromosomal location as VPI-1, contains an integrase gene with 94% nucleotide and 100% protein identity to the VPI-1 integrase, and attachment (att) sites 100% identical to those found in VPI-1. However, instead of TCP and the other accessory genes present in VPI-1, GIVchS12 contains a CRISPR-Cas element and a type VI secretion system (T6SS). GIs similar to GIVchS12 were identified in other V. cholerae genomes, also containing CRISPR-Cas elements and/or T6SS's. This study highlights the diversity of GIs circulating in natural V. cholerae populations and identifies GIs with VPI-1 recombination characteristics as a propagator of CRISPR-Cas and T6SS modules.

  15. Tryptophan-mediated dimerization of the TssL transmembrane anchor is required for Type VI secretion system activity.

    PubMed

    Zoued, Abdelrahim; Duneau, Jean-Pierre; Durand, Eric; España, Alexandre P; Journet, Laure; Guerlesquin, Françoise; Cascales, Eric

    2018-02-16

    The Type VI secretion system (T6SS) is a multiprotein complex used by bacteria to deliver effectors into target cells. The T6SS comprises a bacteriophage-like contractile tail structure anchored to the cell envelope by a membrane complex constituted of the TssJ outer membrane lipoprotein and the TssL and TssM inner membrane proteins. TssJ establishes contact with the periplasmic domain of TssM whereas the transmembrane segments of TssM and its cytoplasmic domain interact with TssL. TssL protrudes in the cytoplasm but is anchored by a C-terminal transmembrane helix (TMH). Here, we show that TssL TMH dimerization is required for the stability of the protein and for T6SS function. Using the TOXCAT assay and point mutations of the 23 residues of the TssL TMH we identified Thr194 and Trp199 as necessary for TssL TMH dimerization. NMR hydrogen-deuterium exchange experiments demonstrated the existence of a dimer with the presence of Trp185 and Trp199 at the interface. A structural model based on molecular dynamics simulations shows that TssL TMH dimer formation involves π-π interactions resulting from the packing of the two Trp199 rings at the C-terminus and of the six aromatic rings of Tyr184, Trp185 and Trp188 at the N-terminus of the TMH. Copyright © 2018. Published by Elsevier Ltd.

  16. The Effects of Continuities in Parent and Peer Aggression on Relational Intimate Partner Violence in the Transition to Young Adulthood.

    PubMed

    Leadbeater, Bonnie J; Sukhawathanakul, Paweena; Holfeld, Brett; Temple, Jeffery R

    2017-04-01

    Past research suggests that exposure to parent psychological control and peer relational aggression and victimization experienced during adolescence is associated with relational intimate partner violence (IPV) in young adults (ages 22 to 29). However, the effects of continuities in these concerns across young adulthood have not been assessed. Relational IPV is characterized by behaviors intended to damage partner's emotional well-being and security in a romantic relationship (e.g., threatening to break up, purposefully ignoring, or causing jealousy). Six waves of data were collected biennially across 10 years from 662 participants (342 females) who were 12 to 18 years old in 2003. The 334 youth who were in a current romantic relationship at the sixth wave (T6, 10 years later) are the focus of this research. Tests of hypothesized structural equation models indicated that adolescent experiences of psychological control with fathers (but not mothers) predicted relational IPV at T6, but this association was no longer significant after accounting for continuity in father psychological control in young adulthood. Adolescent experiences of relational aggression and victimization with peers also predicted relational IPV at T6. This association remained significant for males, only, after continuity in experiences of relational aggression and victimization with peers in young adulthood was included in the model. Implications for the prevention of relational IPV in adolescence and young adults are discussed.

  17. An interbacterial NAD(P) + glycohydrolase toxin requires elongation factor Tu for delivery to target cells

    DOE PAGES

    Whitney, John C.; Quentin, Dennis; Sawai, Shin; ...

    2015-10-08

    Type VI secretion (T6S) influences the composition of microbial communities by catalyzing the delivery of toxins between adjacent bacterial cells. Here, we demonstrate that a T6S integral membrane toxin from Pseudomonas aeruginosa, Tse6, acts on target cells by degrading the universally essential dinucleotides NAD + and NADP +. Structural analyses of Tse6 show that it resembles mono-ADP-ribosyltransferase proteins, such as diphtheria toxin, with the exception of a unique loop that both excludes proteinaceous ADP-ribose acceptors and contributes to hydrolysis. We find that entry of Tse6 into target cells requires its binding to an essential housekeeping protein, translation elongation factor Tumore » (EF-Tu). These proteins participate in a larger assembly that additionally directs toxin export and provides chaperone activity. Lastly, visualization of this complex by electron microscopy defines the architecture of a toxin-loaded T6S apparatus and provides mechanistic insight into intercellular membrane protein delivery between bacteria.« less

  18. A type VI secretion-related pathway in Bacteroidetes mediates interbacterial antagonism.

    PubMed

    Russell, Alistair B; Wexler, Aaron G; Harding, Brittany N; Whitney, John C; Bohn, Alan J; Goo, Young Ah; Tran, Bao Q; Barry, Natasha A; Zheng, Hongjin; Peterson, S Brook; Chou, Seemay; Gonen, Tamir; Goodlett, David R; Goodman, Andrew L; Mougous, Joseph D

    2014-08-13

    Bacteroidetes are a phylum of Gram-negative bacteria abundant in mammalian-associated polymicrobial communities, where they impact digestion, immunity, and resistance to infection. Despite the 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. 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.

  20. 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.

  1. Agrobacterium tumefaciens Deploys a Superfamily of Type VI Secretion DNase Effectors as Weapons for Interbacterial Competition In Planta

    PubMed Central

    Ma, Lay-Sun; Hachani, Abderrahman; Lin, Jer-Sheng; Filloux, Alain; Lai, Erh-Min

    2014-01-01

    Summary The type VI secretion system (T6SS) is a widespread molecular weapon deployed by many Proteobacteria to target effectors/toxins into both eukaryotic and prokaryotic cells. We report that Agrobacterium tumefaciens, a soil bacterium that triggers tumorigenesis in plants, produces a family of type VI DNase effectors (Tde) that are distinct from previously known polymorphic toxins and nucleases. Tde exhibits an antibacterial DNase activity that relies on a conserved HxxD motif and can be counteracted by a cognate immunity protein, Tdi. In vitro, A. tumefaciens T6SS could kill Escherichia coli but triggered a lethal counterattack by Pseudomonas aeruginosa upon injection of the Tde toxins. However, in an in planta coinfection assay, A. tumefaciens used Tde effectors to attack both siblings cells and P. aeruginosa to ultimately gain a competitive advantage. Such acquired T6SS-dependent fitness in vivo and conservation of Tde-Tdi couples in bacteria highlights a widespread antibacterial weapon beneficial for niche colonization. PMID:24981331

  2. 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. © 2015 WILEY Periodicals, Inc.

  3. 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

  4. Killing by Type VI secretion drives genetic phase separation and correlates with increased cooperation

    PubMed Central

    McNally, Luke; Bernardy, Eryn; Thomas, Jacob; Kalziqi, Arben; Pentz, Jennifer; Brown, Sam P.; Hammer, Brian K.; Yunker, Peter J.; Ratcliff, William C.

    2017-01-01

    By nature of their small size, dense growth and frequent need for extracellular metabolism, microbes face persistent public goods dilemmas. Genetic assortment is the only general solution stabilizing cooperation, but all known mechanisms structuring microbial populations depend on the availability of free space, an often unrealistic constraint. Here we describe a class of self-organization that operates within densely packed bacterial populations. Through mathematical modelling and experiments with Vibrio cholerae, we show how killing adjacent competitors via the Type VI secretion system (T6SS) precipitates phase separation via the ‘Model A' universality class of order-disorder transition mediated by killing. We mathematically demonstrate that T6SS-mediated killing should favour the evolution of public goods cooperation, and empirically support this prediction using a phylogenetic comparative analysis. This work illustrates the twin role played by the T6SS, dealing death to local competitors while simultaneously creating conditions potentially favouring the evolution of cooperation with kin. PMID:28165005

  5. Pharyngeal airway space, hyoid bone position, and head posture after bimaxillary orthognathic surgery in Class III patients: long-term evaluation.

    PubMed

    Efendiyeva, Ruchengiz; Aydemir, Halise; Karasu, Hakan; Toygar-Memikoğlu, Ufuk

    2014-09-01

    (1) To determine the effect of bimaxillary orthognathic surgery on pharyngeal airway, hyoid bone, and craniocervical posture in Class III bimaxillary surgery patients. (2) To evaluate short-term and long-term results. (3) To compare short- and long-term values. Twenty-six Class III adult patients treated with bimaxillary surgery were included in the study. Cephalometric records were taken before treatment (T1), before surgery (T2), and 5 months (T3), 1.4 years (T4), 3 years (T5), and 5 years (T6) postsurgery. No significant differences were identified in craniocervical angulation between time intervals. There was a significant superior movement of hyoid bone at postsurgery (T3; P < .05); however, adaptation occurred to the normal position in the long term. A nonsignificant decrease occurred at the oropharyngeal middle pharyngeal distance parameter; however, this was compensated with a significant increase between T5 and T6 (P < .001). A significant decrease was observed in the hypopharyngeal Go-P parameter between T3 and T1 (P < .01), but it recovered with a nonsignificant increase in the long term. A significant increase in nasopharyngeal area was observed between T3 and T1 (P < .05). The hypopharyngeal area significantly increased between T5 and T6, and PNS-R significantly increased between T3 and T1 (P < .05). The pharyngeal areas adversely affected after surgery recover at long-term follow-up; thus, adaptation occurs after bimaxillary surgery.

  6. Genetic Architecture of Abdominal Pigmentation in Drosophila melanogaster.

    PubMed

    Dembeck, Lauren M; Huang, Wen; Magwire, Michael M; Lawrence, Faye; Lyman, Richard F; Mackay, Trudy F C

    2015-05-01

    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.

  7. An Interbacterial NAD(P)+ Glycohydrolase Toxin Requires Elongation Factor Tu for Delivery to Target Cells

    SciTech Connect

    Whitney, John C.; Quentin, Dennis; Sawai, Shin

    2015-10-08

    Type VI secretion (T6S) influences the composition of microbial communities by catalyzing the delivery of toxins between adjacent bacterial cells. Here, we demonstrate that a T6S integral membrane toxin from Pseudomonas aeruginosa, Tse6, acts on target cells by degrading the universally essential dinucleotides NAD + and NADP +. Structural analyses of Tse6 show that it resembles mono-ADP-ribosyltransferase proteins, such as diphtheria toxin, with the exception of a unique loop that both excludes proteinaceous ADP-ribose acceptors and contributes to hydrolysis. We find that entry of Tse6 into target cells requires its binding to an essential housekeeping protein, translation elongation factor Tumore » (EF-Tu). These proteins participate in a larger assembly that additionally directs toxin export and provides chaperone activity. Visualization of this complex by electron microscopy defines the architecture of a toxin-loaded T6S apparatus and provides mechanistic insight into intercellular membrane protein delivery between bacteria.« less

  8. Comparative genome analyses of Serratia marcescens FS14 reveals its high antagonistic potential.

    PubMed

    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.

  9. 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

  10. Characteristics of Vibrio parahaemolyticus isolates obtained from crayfish (Procambarus clarkii) in freshwater.

    PubMed

    Dong, Xingxing; Li, Zhi; Wang, Xiaohong; Zhou, Min; Lin, Li; Zhou, Yang; Li, Jinquan

    2016-12-05

    Vibrio parahaemolyticus usually occurs in coastal areas and is generally recognized as a marine bacterium. It has become the leading cause of gastroenteritis worldwide. In the present study, 96 V. parahaemolyticus isolates were obtained from freshwater crayfish (Procambarus clarkii) and classified by multilocus sequence typing. Fifty-three sequence types (STs) were identified among the 96 isolates analyzed, 38 of which were novel STs. These isolates fell into six groups and 42 singletons, suggesting a high level of genetic diversity. Screening for 9 virulence and virulence-related genes in the isolates revealed that 40 isolates contained more than two genes with possible roles in pathogenicity. The virulence of the representative isolates VP66 (trh+, ureC+, T3SS1+, T3SS2β+, T6SS2+) and VP80 (T3SS1+, T6SS1+, T6SS2+) were further assessed in zebrafish and mouse infection model in vivo, and the tested isolates were shown to be lethal to both zebrafish and mice. These results suggest that crayfish may serve as a carrier of V. parahaemolyticus in freshwater, and that some isolates may have the potential to cause foodborne disease in humans. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Caffeine Inhibits the Activation of Hepatic Stellate Cells Induced by Acetaldehyde via Adenosine A2A Receptor Mediated by the cAMP/PKA/SRC/ERK1/2/P38 MAPK Signal Pathway

    PubMed Central

    Yang, Wanzhi; Wang, Qi; Zhao, Han; Yang, Feng; Lv, Xiongwen; Li, Jun

    2014-01-01

    Hepatic stellate cell (HSC) activation is an essential event during alcoholic liver fibrosis. Evidence suggests that adenosine aggravates liver fibrosis via the adenosine A2A receptor (A2AR). Caffeine, which is being widely consumed during daily life, inhibits the action of adenosine. In this study, we attempted to validate the hypothesis that caffeine influences acetaldehyde-induced HSC activation by acting on A2AR. Acetaldehyde at 50, 100, 200, and 400 μM significantly increased HSC-T6 cells proliferation, and cell proliferation reached a maximum at 48 h after exposure to 200 μM acetaldehyde. Caffeine and the A2AR antagonist ZM241385 decreased the cell viability and inhibited the expression of procollagen type I and type III in acetaldehyde-induced HSC-T6 cells. In addition, the inhibitory effect of caffeine on the expression of procollagen type I was regulated by A2AR-mediated signal pathway involving cAMP, PKA, SRC, and ERK1/2. Interestingly, caffeine’s inhibitory effect on the expression of procollagen type III may depend upon the A2AR-mediated P38 MAPK-dependent pathway. Conclusions: Caffeine significantly inhibited acetaldehyde-induced HSC-T6 cells activation by distinct A2AR mediated signal pathway via inhibition of cAMP-PKA-SRC-ERK1/2 for procollagen type I and via P38 MAPK for procollagen type III. PMID:24682220

  12. 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. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. EsrB negatively regulates expression of the glutamine sythetase GlnA in the fish pathogen Edwardsiella piscicida.

    PubMed

    Guan, Yunpeng; Yin, Kaiyu; Zhou, Mian; Yang, Minjun; Zhang, Yuanxing; Liu, Xiaohong; Wang, Qiyao

    2018-02-01

    Edwardsiella piscicida is a gram-negative bacterial pathogen invading a wide range of fish species. Response regulator EsrB is essential for the activation of type III and type VI secretion systems (T3/T6SS). In this study, proteomes of the wild-type E. piscicida EIB202 and ΔesrB mutant strains were compared to identify the regulon components of EsrB cultured in DMEM allowing T3/T6SS expression. As a result, 19 proteins showed different expression, which were identified to be associated with T3/T6SS, related to amino acid transport and metabolism, and energy production. Particularly, GlnA, a glutamine synthetase essential for ammonia assimilation and glutamine biosynthesis from glutamate, was found to be regulated negatively by EsrB. Moreover, GlnA affected bacterial growth in vitro and bacterial colonization in vivo. Collectively, our results indicated that EsrB plays important roles in regulating the expression of metabolic pathways and virulence genes, including glutamine biosynthesis in E. piscicida during infection. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Subinhibitory Concentration of Kanamycin Induces the Pseudomonas aeruginosa type VI Secretion System

    PubMed Central

    Jones, Cerith; Allsopp, Luke; Horlick, Jack; Kulasekara, Hemantha; Filloux, Alain

    2013-01-01

    Pseudomonas aeruginosa is a Gram-negative bacterium found in natural environments including plants, soils and warm moist surfaces. This organism is also in the top ten of nosocomial pathogens, and prevalent in cystic fibrosis (CF) lung infections. The ability of P. aeruginosa to colonize a wide variety of environments in a lasting manner is associated with the formation of a resistant biofilm and the capacity to efficiently outcompete other microorganisms. Here we demonstrate that sub-inhibitory concentration of kanamycin not only induces biofilm formation but also induces expression of the type VI secretion genes in the H1-T6SS cluster. The H1-T6SS is known for its role in toxin production and bacterial competition. We show that the antibiotic induction of the H1-T6SS only occurs when a functional Gac/Rsm pathway is present. These observations may contribute to understand how P. aeruginosa responds to antibiotic producing competitors. It also suggests that improper antibiotic therapy may enhance P. aeruginosa colonization, including in the airways of CF patients. PMID:24260549

  15. Haemolysin Co-regulated Protein is an Exported Receptor and Chaperone of Type VI Secretion Substrates

    PubMed Central

    Silverman, Julie M.; Agnello, Danielle M.; Zheng, Hongjin; Andrews, Benjamin T.; Li, Mo; Catalano, Carlos E.; Gonen, Tamir; Mougous, Joseph D.

    2013-01-01

    SUMMARY Secretion systems require high fidelity mechanisms to discriminate substrates amongst the vast cytoplasmic pool of proteins. Factors mediating substrate recognition by the type VI secretion system (T6SS) of Gram-negative bacteria, a widespread pathway that translocates effector proteins into target bacterial cells, have not been defined. We report that haemolysin co-regulated protein (Hcp), a ring-shaped hexamer secreted by all characterized T6SSs, binds specifically to cognate effector molecules. Electron microscopy analysis of an Hcp–effector complex from Pseudomonas aeruginosa revealed the effector bound to the inner surface of Hcp. Further studies demonstrated that interaction with the Hcp pore is a general requirement for secretion of diverse effectors encompassing several enzymatic classes. Though previous models depict Hcp as a static conduit, our data indicate it is a chaperone and receptor of substrates. These unique functions of a secreted protein highlight fundamental differences between the export mechanism of T6 and other characterized secretory pathways. PMID:23954347

  16. Comparative Genomics of Multiple Strains of Pseudomonas cannabina pv. alisalensis, a Potential Model Pathogen of Both Monocots and Dicots

    PubMed Central

    Sarris, Panagiotis F.; Trantas, Emmanouil A.; Baltrus, David A.; Bull, Carolee T.; Wechter, William Patrick; Yan, Shuangchun; Ververidis, Filippos; Almeida, Nalvo F.; Jones, Corbin D.; Dangl, Jeffery L.; Panopoulos, Nickolas J.; Vinatzer, Boris A.; Goumas, Dimitrios E.

    2013-01-01

    Comparative genomics of closely related pathogens that differ in host range can provide insights into mechanisms of host-pathogen interactions and host adaptation. Furthermore, sequencing of multiple strains with the same host range reveals information concerning pathogen diversity and the molecular basis of virulence. Here we present a comparative analysis of draft genome sequences for four strains of Pseudomonas cannabina pathovar alisalensis (Pcal), which is pathogenic on a range of monocotyledonous and dicotyledonous plants. These draft genome sequences provide a foundation for understanding host range evolution across the monocot-dicot divide. Like other phytopathogenic pseudomonads, Pcal strains harboured a hrp/hrc gene cluster that codes for a type III secretion system. Phylogenetic analysis based on the hrp/hrc cluster genes/proteins, suggests localized recombination and functional divergence within the hrp/hrc cluster. Despite significant conservation of overall genetic content across Pcal genomes, comparison of type III effector repertoires reinforced previous molecular data suggesting the existence of two distinct lineages within this pathovar. Furthermore, all Pcal strains analyzed harbored two distinct genomic islands predicted to code for type VI secretion systems (T6SSs). While one of these systems was orthologous to known P. syringae T6SSs, the other more closely resembled a T6SS found within P. aeruginosa. In summary, our study provides a foundation to unravel Pcal adaptation to both monocot and dicot hosts and provides genetic insights into the mechanisms underlying pathogenicity. PMID:23555661

  17. Earwax and level of paralysis.

    PubMed

    Frisbie, J H; Zahn, E H

    2003-04-01

    Inception cohort. The clinical impression that earwax is uncommonly frequent among spinal cord injury patients with high levels of paralysis was tested. Veterans Administration Hospital, USA. A cohort of 15 chronically paralyzed patients, motor complete, living as residents in a long-term care facility was offered monthly irrigations of the ears for removal of wax over a 6-month period. The number of requests was tabulated. All ears were examined once on a single day to determine point prevalence. The accumulated wax graded as absent or small, moderate or large. Two patients with C2 lesions, aged 37 and 52 years and paralyzed 15 and 16 years, were compared with 13 patients at C4-T6 aged 44-78 years, median 62 years, and paralyzed 2-33 years, median 24 years. Over a 6-month observation period, 10 irrigations were requested by the C2 patients and three by the C4-T6 patients. The reasons were hearing loss. Wax was found and removed, and symptoms were relieved in all instances, P&<0.001. The spot survey revealed earwax of moderate or large amounts in four of four C2 patient ears and in two of 24 C4-T6 patient ears, P=0.001. Patients with C2 tetraplegia accumulate more earwax and request its removal more often than patients with lower levels of paralysis.

  18. Killing mediated spatial structure in V. Cholerae biofilms

    NASA Astrophysics Data System (ADS)

    Yanni, David

    Most bacteria live in biofilms, which are implicated in 60 - 80 % of microbial infections in the body. The spatial structure of a biofilm confers advantages to its member-cells, such as antibiotic resistance, and is strongly affected by competition between strains and taxa. However, A complete picture of how competition affects the self-organized structure of these complex, far-from-equilibrium systems, is yet to emerge. To that end, we investigate phase separation dynamics driven by T6SS-facilitated bacterial warfare in a system composed of two strains of mutually antagonistic V. cholerae. T6SS is a contact mediated killing mechanism present in 25 % of all gram negative bacteria, and has been shown by recent work to play a major role in the spatial assortment of biofilms. T6SS events induce lysis, causing variations in local mechanical pressure, and acting as thermalizing events. We study cells immobilized in biofilms at the air-solid interface, so our experimental system represents a different type active matter, wherein activity is due to cell death and reproduction, not mobility. Here, we show how that activity imposes a constraint of minimal curvature on strain-strain interfaces; an effective Laplace pressure is characterized which governs interfacial dynamics.

  19. Type VI secretion system contributes to Enterohemorrhagic Escherichia coli virulence by secreting catalase against host reactive oxygen species (ROS).

    PubMed

    Wan, Baoshan; Zhang, Qiufen; Ni, Jinjing; Li, Shuxian; Wen, Donghua; Li, Jun; Xiao, Haihan; He, Ping; Ou, Hong-Yu; Tao, Jing; Teng, Qihui; Lu, Jie; Wu, Wenjuan; Yao, Yu-Feng

    2017-03-01

    Enterohemorrhagic Escherichia coli (EHEC) is one major type of contagious and foodborne pathogens. The type VI secretion system (T6SS) has been shown to be involved in the bacterial pathogenicity and bacteria-bacteria competition. Here, we show that EHEC could secrete a novel effector KatN, a Mn-containing catalase, in a T6SS-dependent manner. Expression of katN is promoted by RpoS and OxyR and repressed by H-NS, and katN contributes to bacterial growth under oxidative stress in vitro. KatN could be secreted into host cell cytosol after EHEC is phagocytized by macrophage, which leads to decreased level of intracellular reactive oxygen species (ROS) and facilitates the intramacrophage survival of EHEC. Finally, animal model results show that the deletion mutant of T6SS was attenuated in virulence compared with the wild type strain, while the deletion mutant of katN had comparable virulence to the wild type strain. Taken together, our findings suggest that EHEC could sense oxidative stress in phagosome and decrease the host cell ROS by secreting catalase KatN to facilitate its survival in the host cells.

  20. An Interbacterial NAD(P)+ Glycohydrolase Toxin Requires Elongation Factor Tu for Delivery to Target Cells

    SciTech Connect

    Whitney, John C.; Quentin, Dennis; Sawai, Shin; LeRoux, Michele; Harding, Brittany N.; Ledvina, Hannah E.; Tran, Bao Q.; Robinson, Howard; Goo, Young Ah; Goodlett, David R.; Raunser, Stefan; Mougous, Joseph D.

    2015-10-08

    Type VI secretion (T6S) influences the composition of microbial communities by catalyzing the delivery of toxins between adjacent bacterial cells. Here, we demonstrate that a T6S integral membrane toxin from Pseudomonas aeruginosa, Tse6, acts on target cells by degrading the universally essential dinucleotides NAD+ and NADP+. Structural analyses of Tse6 show that it resembles mono-ADP-ribosyltransferase proteins, such as diphtheria toxin, with the exception of a unique loop that both excludes proteinaceous ADP-ribose acceptors and contributes to hydrolysis. We find that entry of Tse6 into target cells requires its binding to an essential housekeeping protein, translation elongation factor Tu (EF-Tu). These proteins participate in a larger assembly that additionally directs toxin export and provides chaperone activity. Visualization of this complex by electron microscopy defines the architecture of a toxin-loaded T6S apparatus and provides mechanistic insight into intercellular membrane protein delivery between bacteria.

  1. The effect of scandium addition on microstructure and mechanical properties of Al–Si–Mg alloy: A multi-refinement modifier

    SciTech Connect

    Xu, Cong, E-mail: xucong55555@gmail.com; Xiao, Wenlong, E-mail: wlxiao@buaa.edu.cn; Hanada, Shuji

    2015-12-15

    Effect of scandium (Sc) additions on the microstructure, mechanical properties and fracture behavior of Al–Si–Mg casting alloy (F357) were systematically investigated. It was found that Sc addition caused a multi-refining efficiency on the microstructure of as-cast F357 alloy, including refinement of grains and secondary dendrite arm spacing (SDAS), modification of eutectic Si and harmless disposal of β-Al{sub 5}FeSi phase. Subsequent T6 heat treatment had further induced the complete spheroidization of eutectic Si and precipitation of fine secondary Al{sub 3}Sc dispersoids in the Sc modified alloys. Thus the mechanical properties, especially the ductility, were significantly enhanced by the addition of Scmore » combined with the heat treatment. The highest ultimate tensile strength, yield strength and elongation were achieved in 0.8 wt.% Sc modified F357 alloy combined with T6 heat treatment. Furthermore, fractographic examinations indicated that the ductile fracture mechanism served as a dominate role in the modified alloys due to the formation of fine, deep and uniformly distributed dimples. - Highlights: • Detailed characterization of the multi-refining microstructure of Sc modified F357 alloy was performed. • The multi-refinement was proposed to refine grain and SDAS, modify eutectic Si and β-phase. • Sc modifier combined with T6 treatment is effective in improving tensile properties. • Modification of eutectic Si in F357 alloy with Sc is consistent with the IIT mechanism.« less

  2. 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.

  3. An interbacterial NAD(P)+ glycohydrolase toxin requires elongation factor Tu for delivery to target cells

    SciTech Connect

    Whitney, John C.; Quentin, Dennis; Sawai, Shin; LeRoux, Michele; Harding, Brittany N.; Ledvina, Hannah E.; Tran, Bao Q.; Robinson, Howard; Goo, Young Ah; Goodlett, David R.; Raunser, Stefan; Mougous, Joseph D.

    2015-10-08

    Type VI secretion (T6S) influences the composition of microbial communities by catalyzing the delivery of toxins between adjacent bacterial cells. Here, we demonstrate that a T6S integral membrane toxin from Pseudomonas aeruginosa, Tse6, acts on target cells by degrading the universally essential dinucleotides NAD+ and NADP+. Structural analyses of Tse6 show that it resembles mono-ADP-ribosyltransferase proteins, such as diphtheria toxin, with the exception of a unique loop that both excludes proteinaceous ADP-ribose acceptors and contributes to hydrolysis. We find that entry of Tse6 into target cells requires its binding to an essential housekeeping protein, translation elongation factor Tu (EF-Tu). These proteins participate in a larger assembly that additionally directs toxin export and provides chaperone activity. Lastly, visualization of this complex by electron microscopy defines the architecture of a toxin-loaded T6S apparatus and provides mechanistic insight into intercellular membrane protein delivery between bacteria.

  4. Transcriptome analysis of Acidovorax avenae subsp. avenae cultivated in vivo and co-culture with Burkholderia seminalis

    PubMed Central

    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

  5. 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

  6. Molecular mechanism of DNA recognition by the alpha subunit of the Oxytricha telomere binding protein.

    PubMed

    Laporte, L; Benevides, J M; Thomas, G J

    1999-01-12

    Interactions between telomeric DNA and the alpha subunit of the heterodimeric telomere binding protein of Oxytricha nova have been probed by Raman spectroscopy, CD spectroscopy, and nondenaturing gel electrophoresis. Telomeric sequences investigated include the Oxytricha 3' overhang, d(T4G4)2, and the related sequence dT6(T4G4)2, which incorporates a 5'-thymidylate leader. Corresponding nontelomeric isomers, d(TG)8 and dT6(TG)8, have also been investigated. Both d(T4G4)2 and dT6(T4G4)2 form stable hairpins that contain Hoogsteen G.G base pairs [Laporte, L., and Thomas, G. J., Jr. (1998) J. Mol. Biol. 281, 261-270]. The alpha subunit binds specifically and stoichiometrically to the dT6(T4G4)2 hairpin and alters its secondary structure by inducing conformational changes in the 5'-thymidylate leader without extensive disruption of G.G base pairing. Conversely, binding of the alpha subunit to d(T4G4)2 eliminates G.G pairing and unfolds the hairpin. DNA unfolding is accompanied by conformational changes affecting both the backbone and dG residues, as evidenced by Raman and CD spectra. Interestingly, the alpha subunit also forms complexes with the nontelomeric isomers, d(TG)8 and dT6(TG)8, evidenced by altered electrophoretic mobility in nondenaturing gels; however, Raman and CD spectra of complexes of the alpha subunit with nontelomeric DNA suggest no significant changes in backbone or deoxynucleoside conformations. Similarly, the alpha subunit binds to but does not appreciably alter the secondary structure of duplex DNA. The present results show that while the alpha subunit has the capacity to bind to Watson-Crick and different non-Watson-Crick motifs, DNA refolding is specific to the Oxytricha telomeric hairpin and the retention of G.G pairing is specific to the telomeric sequence incorporating the 5' leading sequence. A model is proposed for alpha subunit binding to telomeric DNA, and the physiological role of the alpha subunit in telomere organization is discussed.

  7. Light weight and high strength materials made of recycled steel and aluminum

    NASA Astrophysics Data System (ADS)

    Nounezi, Thomas

    Recycling has proven not only to address today's economical, environmental and social issues, but also to be imperative for the sustainability of human technology. The current thesis has investigated the feasibility of a new philosophy for Recycling (Alloying-Recycling) using steel 1020 and aluminum 6061T6. The study was limited to the metallurgical aspects only and has highlighted the potential of recycled alloys made of recycled aluminum and steel to exhibit substantially increased wear resistance and strength-to-weight ratio as compared to initial primary materials. Three alloy-mixtures are considered: TN3 (5wt% 1020 +95wt% 6061T6); TN5 (0.7wt% 1020 + 99.3wt% 6061T6); and TN4 (10wt% 6061T6 + 90wt% 1020). A Tucker induction power supply system (3kW; 135-400 kHz) is used to melt the alloy mixtures for casting in graphite crucibles. Heat treatment of the cast samples is done using a radiation box furnace. Microscopy, Vickers hardness and pin-on-disc abrasive wear tests are performed. Casting destroyed the initial microstructures of the alloys leading to a hardness reduction in the as-cast and solution heat-treated aluminum rich samples to 60 Hv from 140 Hv. Ageing slightly increased the hardness of the cast samples and provided a wear resistance two times higher than that of the initial 6061T6 material. On the steel rich side, the hardness of the as-cast TN4 was 480 Hv, which is more than twice as high as the initial hardness of steel 1020 of 202 Hv; this hints to strong internal and residual stress, probably martensite formation during fast cooling following casting. Solution heat treatment lowered the hardness to the original value of steel 1020, but provided about ten (10) times higher wear resistance; this suggests higher ductility and toughness of normalised TN4 as compared to 1020. In addition, TN4 exhibits about 25% weight reduction as compared to 1020. The actual recycling process and the effect of non-metallic impurities shall be investigated in future

  8. 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.

  9. Predicted geographic ranges for North American sylvatic Trichinella species.

    PubMed

    Masuoka, Penny M; Burke, Robin; Colaccico, Michelle; Razuri, Hugo; Hill, Dolores; Murrell, K Darwin

    2009-08-01

    Because of a lack of comprehensive surveys, the geographic distributions of the North American species of encapsulating Trichinella (T. nativa and its variant T6, T. murrelli, and T. spiralis) are poorly characterized in detail. These species are potentially zoonotic; therefore, biogeographic information is critical to monitoring their status and any distribution changes due to climatic and man-made environmental impacts. The maximum entropy (Maxent) program was used to model predicted ranges for these sylvatic Trichinella spp., using a limited number of available location records with confirmed species identifications collected over 55 yr throughout North America. The resulting prediction models were shown to be robust, and the species maps created are presented. The predicted range of T. nativa is primarily north of the 48 degrees - 52 degrees latitudes, overlapping the Tundra, sub-Arctic, and Warm Continental eco-regions. Its sympatric genotypic variant, T6, has a predicted range covering primarily the sub-Arctic and mountainous Temperate Steppe eco-regions, the latter extending below 48 degrees N latitude. In the east, the T6 range includes the Warm Continental and the mountainous Hot Continental eco-regions; the T6 range is also predicted to extend to the Sierra Madre Mountains of Mexico. The most probable range of T. murrelli is centered in the Midwest within the Hot Continental and Prairie eco-regions, with an extension southward to the Subtropical and Tropical/Subtropical Steppe and Desert eco-regions. In the west, it exists in a restricted range characterized as mountainous Mediterranean. The most probable distribution of sylvatic T. spiralis is along the humid east North American coast (Hot Continental south to Subtropical), and along the coast of northwest North America (Marine) to Alaska (subArctic and Tundra). Its most southerly range extends into central Mexico (Tropical/Subtropical Desert). The difference in relative freeze resistance between T

  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

    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 personally

  12. Comparison of enamel matrix derivative (Emdogain) and subepithelial connective tissue graft for root coverage in patients with multiple gingival recession defects: A randomized controlled clinical study.

    PubMed

    Alexiou, Angeliki; Vouros, Ioannis; Menexes, Georgios; Konstantinidis, Antonis

    2017-01-01

    The purpose of the present study was to compare the clinical efficiency of enamel matrix derivative (EMD) placed under a coronally advanced flap (CAF; test group), to a connective tissue graft (CTG) placed under a CAF (control group), in patients with multiple recession defects. Twelve patients with multiple Miller's Class I or II gingival recessions in contralateral quadrants of the maxilla were selected. The primary outcome variable was the change in depth of the buccal recession (REC), at 6 months (T6) after surgery. The secondary outcome parameters included the clinical attachment level (CAL), the probing pocket depth (PPD), and the width of keratinized gingiva (WKT) apical to the recession. Recession defects were randomly divided to the test or control group by using a computer-generated randomization list. Data were analyzed within the frame of Mixed Linear Models with the ANOVA method. There were no statistically significantly differences observed between test and control groups in regards with the depth of buccal recession with a mean REC of 1.82 mm (CTG) and 1.72 mm (EMD) respectively. Similarly the mean PPD value was 1.3 mm for both groups at T6, while the respective value for CAL was 1.7 mm (EMD) and 1.8 mm (CTG). Statistically significant differences were observed only for the WKT, which were 3.0 mm and 3.6 mm for the test and control groups respectively (P < .001) at T6. The use of EMD in conjunction with a CAF resulted in similar results as compared to the CTG plus CAF.

  13. [Effects of mulching on soil moisture in a dryland winter wheat field, Northwest China].

    PubMed

    Fan, Ying-Dan; Chai, Shou-Xi; Cheng, Hong-Bo; Chen, Yu-Zhang; Yang, Chang-Gang; Huang, Cai-Xia; Chang, Lei; Pang, Lei

    2013-11-01

    This paper studied the effects of different mulching modes on the soil moisture in a semi-arid rainfed area of Loess Plateau, Northwest China. Seven treatments were installed, i. e., mulching plastic film in summer (T1), mulching plastic film in autumn (T2), mulching 5 cm long wheat straw in summer (T3), mulching whole wheat straw in summer (T4), mulching plastic film in summer plus wheat straw (T5), mulching used plastic film after harvest (T6), and un-mulching (CK). In T6, the soil moisture in different layers at different crop growth stages was all higher than that in CK. In the other five mulching treatments, the soil moisture in 0-90 cm layer before flowering stage was obviously higher, but that in 0-90 cm layer after flowering stage and in 90-200 cm layer during the whole growth season was lower than that of CK. The soil moisture in 0-200 cm layer in T6 during the whole growth period was significantly higher than that in CK, with a difference of 0.9%, but the soil moisture in 0-200 cm layer in other mulching treatments was lower. As compared with plastic film mulching, straw mulching increased the soil moisture in 0-200 cm layer. The soil moisture under mulching with used plastic film after harvest was higher than that under mulching with new plastic film. As compared to CK, the grain yield of winter wheat with plastic film mulching was increased by 20.3%-29.0%, and that With straw mulching was increased by 5.0%-16.7%. There was a significant positive correlation between the crop productivity and the soil water consumption during the growth period (r = 0.77*).

  14. Tetrandrine induces lipid accumulation through blockade of autophagy in a hepatic stellate cell line

    SciTech Connect

    Miyamae, Yusaku, E-mail: ymiyamae@lif.kyoto-u.ac.jp; Nishito, Yukina; Nakai, Naomi

    2016-08-12

    Macroautophagy, or autophagy, is a cellular response in which unnecessary cytoplasmic components, including lipids and organelles, are self-degraded. Recent studies closely related autophagy to activation of hepatic stellate cells (HSCs), a process critical in the pathogenesis of liver fibrosis. During HSC activation, cytoplasmic lipid droplets (LDs) are degraded as autophagic cargo, and then cells express fibrogenic genes. Thus, inhibition of autophagy in HSCs is a potential therapeutic approach for attenuating liver fibrosis. We found that tetrandrine, a bisbenzylisoquinoline alkaloid isolated from Stephania tetrandra, induced lipid accumulation, a phenotype associated with quiescent HSCs, through blockade of autophagy in the rat-derived HSCmore » line HSC-T6. Tetrandrine inhibited autophagic flux without affecting lysosomal function. A phenotypic comparison using siRNA knockdown suggested that tetrandrine may target regulators, involved in fusion between autophagosomes and lysosomes (e.g., syntaxin 17). Moreover, perilipin 1, an LD-coated protein, co-localized specifically with LC3, a marker protein for autophagosomes, in tetrandrine-treated HSC-T6 cells. This suggests a potential role for perilipin 1 in autophagy-mediated LD degradation in HSCs. Our results identified tetrandrine as a potential tool for prevention and treatment of HSC activation. - Highlights: • Autophagy is closely related to lipid degradation in hepatic stellate cells. • Tetrandrine (Tet) causes lipid accumulation via blockade of autophagy in HSC-T6 cells. • Tet blocked autophagy without affecting lysosomal function unlike bafilomycin A{sub 1}. • Perilipin 1 was specifically co-localized with LC3 in Tet-treated cells. • Perilipin 1 may play potential roles in autophagy-mediated lipid degradation.« less

  15. Identification of TPS family members in apple (Malus x domestica Borkh.) and the effect of sucrose sprays on TPS expression and floral induction.

    PubMed

    Du, Lisha; Qi, Siyan; Ma, Juanjuan; Xing, Libo; Fan, Sheng; Zhang, Songwen; Li, Youmei; Shen, Yawen; Zhang, Dong; Han, Mingyu

    2017-11-01

    Trehalose (α-D-glucopyranosyl α-D-glucopyranoside) is a non-reducing disaccharide that serves as a carbon source and stress protectant in apple trees. Trehalose-6-phosphate (T6P) is the biosynthetic precursor of trehalose. It functions as a crucial signaling molecule involved in the regulation of floral induction, and is closely related to sucrose. Trehalose-6-phosphate synthase (TPS) family members are pivotal components of the T6P biosynthetic pathway. The present study identified 13 apple TPS family members and characterized their expression patterns in different tissues and in response to exogenous application of sucrose during floral induction. 'Fuji' apple trees were sprayed with sucrose prior to the onset of floral induction. Bud growth, flowering rate, and endogenous sugar levels were then monitored. The expression of genes associated with sucrose metabolism and flowering were also characterized by RT-quantitative PCR. Results revealed that sucrose applications significantly improved flower production and increased bud size and fresh weight, as well as the sucrose content in buds and leaves. Furthermore, the expression of MdTPS1, 2, 4, 10, and 11 was rapidly and significantly up-regulated in response to the sucrose treatments. In addition, the expression levels of flowering-related genes (e.g., SPL genes, FT1, and AP1) also increased in response to the sucrose sprays. In summary, apple TPS family members were identified that may influence the regulation of floral induction and other responses to sucrose. The relationship between sucrose and T6P or TPS during the regulation of floral induction in apple trees is discussed. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. Micro opioid receptor A118G polymorphism and post-operative pain: opioids' effects on heterozygous patients.

    PubMed

    De Capraris, A; Cinnella, G; Marolla, A; Salatto, P; Da Lima, S; Vetuschi, P; Consoletti, L; Gesualdo, L; Dambrosio, M

    2011-01-01

    The single-nucleotide-polymorphism (SNP) 118A>G in the micro-1 opioid receptor gene (OPRM1) is associated with a decrease in the analgesic effects of opioids. The aim of this study is to assess whether 118A >G polymorphism could influence the analgesic response to opioid-based postoperative pain (POP) therapy. The study consisted of two parts: section alpha, observational, included 199 subjects undergoing scheduled surgical procedures with pain management standardized on surgery invasiveness and on expected level of postoperative pain; section beta, randomized, included 41 women undergoing scheduled caesarean delivery with continuous intra-operative epidural anesthesia and post-operative analgesia (CEA). In both sections, POP was measured over 48 h (T6h-T24h-T48h) by the visual analogue scale (VAS). In section beta we also tested the responsiveness of hypothalamic-pituitary-adrenal axis (HPA) expressed by cortisol levels. In section alpha, with cluster analysis, subjects were analyzed according to their genotype: a group (no. 1) of 34 patients reporting VAS score >3 at every time lapse was identified and included only A118G carriers, while wild-type (A118A - absence of 118A>G polymorphism) patients were unevenly distributed between those with cluster no. 2 (VAS score <3 at every study steps) and those with cluster no. 3 (VAS score progressively reducing from T6h). In section beta, A118G carriers receiving epidural sufentanil had the lowest VAS scores at T24h; also in these patients, cortisol levels remained more stable, with a mild decrease at T6h. This study shows that the OPRM1 118A>G polymorphism affects postoperative pain response in heterozygous patients: they have a different postoperative pain response than patients with wild-type genes, which may affect the efficacy of the analgesic therapy.

  17. A randomised controlled trial of the effect of a head-elevation pillow on intrathecal local anaesthetic spread in caesarean section.

    PubMed

    Elfil, H; Crowley, L; Segurado, R; Spring, A

    2015-11-01

    A head-elevation pillow places a patient in a ramped posture, which maximises the view of the larynx during laryngoscopy, particularly in obese parturients. In our institution an elevation pillow is used pre-emptively for neuraxial anaesthesia. We hypothesised that head-elevation may impair cephalad spread of local anaesthetic before caesarean section resulting in a lower block or longer time to achieve a T6 level. We aimed to investigate the effect of head-elevation on spread of intrathecal local anaesthetics during anaesthesia for caesarean section. One-hundred parturients presenting for caesarean section under combined spinal-epidural anaesthesia were randomised to either the standard supine position with lateral displacement or in the supine position with lateral displacement on an head-elevation pillow. Each patient received intrathecal hyperbaric bupivacaine 11 mg, morphine 100 μg and fentanyl 15 μg. Patients were assessed for adequacy of sensory block (T6 or higher) at 10 min. Sensory block to T6 was achieved within 10 min in 65.9% of parturients in the Elevation Pillow Group compared to 95.7% in the Control Group (P<0.05). Compared to the Control Group, patients in the Elevation Pillow Group had greater requirements for epidural supplementation (43.5% vs 2.1%, P<0.001) or conversion to general anaesthesia (9.3% vs 0%, P<0.04). Use of a ramped position with an head-elevation pillow following injection of the intrathecal component of a combined spinal-epidural anaesthetic for scheduled caesarean section was associated with a significantly lower block height at 10min. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Adhesive arachnoiditis with extensive syringomyelia and giant arachnoid cyst after spinal and epidural anesthesia: a case report.

    PubMed

    Hirai, Takashi; Kato, Tsuyoshi; Kawabata, Shigenori; Enomoto, Mitsuhiro; Tomizawa, Shoji; Yoshii, Toshitaka; Sakaki, Kyohei; Shinomiya, Kenichi; Okawa, Atsushi

    2012-02-01

    A case report of a patient with adhesive arachnoiditis after combined spinal and epidural anesthesia. To report an extremely rare case of paraplegia due to adhesive arachnoiditis with extensive syringomyelia (ES) and a giant anterior arachnoid spinal cyst (AASC) after spinal and epidural anesthesia for obstetric surgery. Progressive inflammation of the arachnoid mater due to trauma, infection, or hydrocortisone was reported as early as the 1970s. However, coexistence of ES and a giant AASC after spinal and epidural anesthesia is extremely rare. A 29-year-old woman suffered from sudden anuresis 5 months after spinal and epidural anesthesia for a cesarean section and subsequently experienced paraplegia and numbness below the chest. Magnetic resonance imaging showed an AASC compressing the spinal cord at T1-T6 and an adhesive lesion at T7. Posterior laminectomy at T6-T7 and adhesiolysis for arachnoid adhesion at T7 were performed. Although there was slight recovery of locomotive function postoperatively, it gradually worsened until 3 years after surgery. Magnetic resonance imaging at that time demonstrated a giant AASC and ES at the lower-thoracic cord. The cord compressed by the AASC became thinner sagittally. Secondary surgery involving posterior laminectomy at T5-T6 and insertion of a cyst-peritoneal shunt into the AASC was performed. The patient could walk without a cane 3 years after the shunt operation, although numbness and motor weakness of the lower extremities remained. Magnetic resonance imaging 3 years after the shunt operation showed a reduction of the AASC and decompression of the cord despite no improvement in ES. This is the first report of a patient with a giant AASC and ES caused by spinal and epidural anesthesia. Although the optimal surgical treatment for these conditions remains unclear, shunting of the cyst effectively prevented the progression of symptoms.

  19. 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.

  20. Protocol for a prospective longitudinal study investigating the participation and educational trajectories of Australian students with autism

    PubMed Central

    Roberts, Jacqueline Margaret Anne; Adams, Dawn; Heussler, Helen; Keen, Deborah; Paynter, Jessica; Trembath, David; Westerveld, Marleen; Williams, Katrina

    2018-01-01

    Introduction Autism is associated with high cost to individuals, families, communities and government. Understanding educational and participation trajectories during the school years, and factors influencing these, is fundamental to reducing financial and personal costs. The primary aim of this study is to document the trajectories of Australian students with autism during their education. The secondary aim is to examine personal (eg, student skills) and environmental (eg, school setting) factors associated with differing trajectories and outcomes. Methods and analysis The cross-sequential longitudinal study will recruit two cohorts of 120 parents/caregivers of children with autism. Cohort 1 aged between 4 and 5 years and cohort 2 between 9 and 10 years to start the study. Information will be gathered from parents, teachers and school principals at six annual time points (T1 to T6). Parents will be emailed a link to an online initial questionnaire (T1) and then contacted annually and asked to complete either an extended questionnaire (T3, T5 and T6) or an abbreviated questionnaire (T2, T4). Where consent is given, the child’s current school will be contacted annually (T1 to T6) and teacher and school principal asked to complete questionnaires about the child and school. Parent and school questionnaires are comprised of questions about demographic and school factors that could influence trajectories and a battery of developmental and behavioural assessment tools designed to assess educational and participation trajectories and outcomes. Surveys will provide longitudinal data on educational and participation trajectories for children and adolescents with autism. In addition cross-sectional comparisons (within or between age groups) at each time point and cohort effects will be explored. Ethics and dissemination Ethics approvals have been granted for this study by all recruiting sites and universities in the project. Study findings will inform policy and practice

  1. 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

  2. Entropy of Feulgen-stained 17-beta-estradiol-transformed human breast epithelial cells as assessed by restriction enzymes and image analysis.

    PubMed

    Mello, Maria Luiza S; Russo, Patricia; Russo, Jose; Vidal, Benedicto C

    2009-06-01

    MCF-10F human breast epithelial cells when transformed with 17-beta-estradiol (E2) give rise to highly invasive C5 cells that generate adenocarcinomas in SCID mice. From these tumors, cell lines such as C5-A6-T6 and C5-A8-T8 have been derived. Variable patterns of chromatin supraorganization have been demonstrated for these cells during the transformation/tumorigenesis progress, when assessing chromatin entropy by image analysis in Feulgen-stained preparations. Since epigenetic dysregulation might contribute to the chromatin textural repatterning in transformed MCF-10F cells, the association of the variable chromatin packing states with global DNA methylation was investigated in these cells after their treatment with restriction enzymes followed by Feulgen staining and chromatin entropy evaluation by image analysis. The results indicate that although -CmCGG- sequences may affect chromatin supraorganization in some of the analyzed cell types (perhaps due to localized hypermethylation), not all the chromatin condensation patterns in these cells with transformation and/or tumorigenesis are associated with DNA methylation (e.g. E2 cells). Chromatin supraorganization remodeling in C5-A6-T6 and C5-A8-T8 cells may be attained by different mechanisms, with C5-A6-T6 chromatin packing states perhaps being associated with local DNA hypermethylation or other epigenetic factors, and C5-A8-T8 likely being associated with global DNA hypomethylation, as reported in the literature for other cell types. Thus, we assume that a variable epigenetic modulation affecting the higher-order packing states of chromatin in the estrogen-transformed MCF-10F cell model could be evident with the chromatin entropy study by image analysis.

  3. 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 Central

    Henry, Rebekah; Vithanage, Nuwan; Harrison, Paul; Seemann, Torsten; Coutts, Scott; Moffatt, Jennifer H.; Nation, Roger L.; Li, Jian; Harper, Marina; Adler, Ben

    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

  4. First test of a cryogenic scintillation module with a CaWO 4 scintillator and a low-temperature photomultiplier down to 6 K

    NASA Astrophysics Data System (ADS)

    Kraus, H.; Mikhailik, V. B.

    2010-09-01

    Future cryogenic experiments searching for rare events require reliable, efficient and robust techniques for the detection of photons at temperatures well below that to which low-temperature photomultipliers (PMT) were characterised. Motivated by this, we investigated the feasibility of a low-temperature PMT for the detection of scintillation from crystalline scintillators at T=6 K. The scintillation module was composed of a CaWO 4 scintillator and a low-temperature PMT D745B from ET Enterprises. The PMT responsivity was studied at T=290, 77 and 6 K using γ-quanta from 241Am (60 keV) and 57Co (122 and 136 keV) sources. We have shown that the low-temperature PMT retains its single photon counting ability even at cryogenic temperatures. At T=6 K, the response of the PMT decreases to 51±13% and 27±6%, when assessed in photon counting and pulse height mode, respectively. Due to the light yield increase of the CaWO 4 scintillating crystal, the overall responsivity of the scintillation modules CaWO 4+PMT is 94±15% (photon counting) and 48±8% (pulse height) when cooling to T=6 K. The dark count rate was found to be 20 s -1. The energy resolution of the module remains similar to that measured at room temperature using either of the detection modes. It is concluded that commercially available low-temperature PMT are well suited for detection of scintillation light at cryogenic temperatures.

  5. Fluoroscope guided epidural needle insertioin in midthoracic region: clinical evaluation of Nagaro's method

    PubMed Central

    Kim, Won Joong; Kim, Tae Hwa; Shin, Hwa Yong; Kang, Hyun; Baek, Chong Wha; Jung, Yong Hun; Kim, Jin Yun; Koo, Gill Hoi; Park, Sun Gyoo

    2012-01-01

    Background In the midthoracic region, a fluroscope guided epidural block has been proposed by using a pedicle as a landmark to show the height of the interlaminar space (Nagaro's method). However, clinical implication of this method was not fully evaluated. We studied the clinical usefulness of a fluoroscope guided thoracic epidural block in the midthoracic region. Methods Twenty four patients were scheduled to receive an epidural block at the T6-7 intervertebral space. The patients were placed in the prone position. The needle entry point was located at the junction between midline of the pedicle paralleled to the midline of the T7 vertebral body (VB) and the lower border of T7 VB on anteroposterior view of the fluoroscope. The needle touched and walked up the lamina, and the interlaminar space (ILS) was sought near the midline of the VB at the height of the pedicle. Results The authors could not insert an epidural needle at T6-7 ILS in two patients and it was instead inserted at T5-6 ILS. However, other patients showed easy insertion at T6-7 ILS. The mean inward and upward angulations were 25° and 55° respectively. The mean actual depth and calculated depth from skin to thoracic epidural space were 5.1 cm and 6.1 cm respectively. Significant correlation between actual needle depth and body weight, podendal index (kg/m) or calculated needle depth was noted. Conclusions The fluorposcope guided epidural block by Nagaro's method was useful in the midthoracic region. However, further study for the caudal shift of needle entry point may be needed. PMID:22679541

  6. Dietary supplementation of walnuts improves memory deficits and learning skills in transgenic mouse model of Alzheimer's disease.

    PubMed

    Muthaiyah, Balu; Essa, Musthafa M; Lee, Moon; Chauhan, Ved; Kaur, Kulbir; Chauhan, Abha

    2014-01-01

    Previous in vitro studies have shown that walnut extract can inhibit amyloid-β (Aβ) fibrillization, can solubilize its fibrils, and has a protective effect against Aβ-induced oxidative stress and cellular death. In this study, we analyzed the effect of dietary supplementation with walnuts on learning skills, memory, anxiety, locomotor activity, and motor coordination in the Tg2576 transgenic (tg) mouse model of Alzheimer's disease (AD-tg). From the age of 4 months, the experimental groups of AD-tg mice were fed custom-mixed diets containing 6% walnuts (T6) or 9% walnuts (T9), i.e., equivalent to 1 or 1.5 oz, respectively, of walnuts per day in humans. The control groups, i.e., AD-tg and wild-type mice, were fed a diet without walnuts (T0, Wt). These experimental and control mice were examined at the ages of 13-14 months by Morris water maze (for spatial memory and learning ability), T maze (for position discrimination learning ability), rotarod (for psychomotor coordination), and elevated plus maze (for anxiety-related behavior). AD-tg mice on the control diet (T0) showed memory deficit, anxiety-related behavior, and severe impairment in spatial learning ability, position discrimination learning ability, and motor coordination compared to the Wt mice on the same diet. The AD-tg mice receiving the diets with 6% or 9% walnuts (T6 and T9) showed a significant improvement in memory, learning ability, anxiety, and motor development compared to the AD-tg mice on the control diet (T0). There was no statistically significant difference in behavioral performance between the T6/T9 mice on walnuts-enriched diets and the Wt group on the control diet. These findings suggest that dietary supplementation with walnuts may have a beneficial effect in reducing the risk, delaying the onset, or slowing the progression of, or preventing AD.

  7. Effect of tool offsetting on microstructure and mechanical properties dissimilar friction stir welded Mg-Al alloys

    NASA Astrophysics Data System (ADS)

    Baghdadi, Amir Hossein; Fazilah Mohamad Selamat, Nor; Sajuri, Zainuddin

    2017-09-01

    Automotive and aerospace industries are attempting to produce lightweight structure by using materials with low density such as aluminum and magnesium alloys to increase the fuel efficiency and consequently reduce the environmental pollution. It can be beneficial to join Mg to Al to acquire ideal performance in special applications. Friction stir welding (FSW) is solid state welding processes and relatively lower temperature of the process compared to fusion welding processes. This makes FSW a potential joining technique for joining of the dissimilar materials. In this study, Mg-Al butt joints were performed by FSW under different tool offset conditions, rotation rates (500-600 rpm) and traverse speeds (20 mm/min) with tool axis offset 1 mm shifted into AZ31B or Al6061 (T6), and without offset. During the welding process AZ31B was positioned at the advancing side (AS) and Al6061 (T6) was located at the retreating side (RS). Defect free AZ31B-Al6061 (T6) dissimilar metal FSW joints with good mechanical properties were obtained with the combination of intermediate rotation rate and low traverse speed pin is in the middle. When tool positioned in -1 mm or +1 mm offsetting, some defects were found in SZ of dissimilar FSWed joints such as cavity, tunnel, and crack. Furthermore, a thin layer of intermetallic compounds was observed in the stir zone at the interface between Mg-Al plates. The strength of the joint was influenced by FSW parameters. Good mechanical properties obtained with the combination of intermediate rotational speed of 600 rpm and low travelling speed of 20 mm/min by locating Mg on advancing side when pin is in the middle. Also, Joint efficiency of the welds prepared in the present study was between 29% and 68% for the different welding parameters.

  8. Inertial sensors for assessment of back movement in horses during locomotion over ground.

    PubMed

    Warner, S M; Koch, T O; Pfau, T

    2010-11-01

    Assessing back movement is an important part of clinical examination in the horse and objective assessment tools allow for evaluating success of treatment. Accuracy and consistency of inertial sensor measurements for quantification of back movement and movement symmetry during over ground locomotion were assessed; sensor measurements were compared to optical motion capture (mocap) and consistency of measurements focusing on movement symmetry was measured. Six nonlame horses were trotted in hand with synchronised mocap and inertial sensor data collection (landmarks: T6, T10, T13, L1 and S3). Inertial sensor data were processed using published methods and symmetry of dorsoventral displacement was assessed based on energy ratio, a Fourier based symmetry measure. Limits of agreement were calculated and visualised to compare mocap and sensor data. Consistency of sensor measurements was assessed using Pearson correlation coefficients and linear regression to investigate the effect of speed on movement symmetry. Dorsoventral and mediolateral sensor displacement was observed to lie within ± 4-5 mm (± 2 s.d., 9-28% of movement amplitude) and energy ratio to lie within ± 0.03 of mocap data. High levels of correlation were found between strides and trials (0.86-1.0) for each horse and each sensor and variability of symmetry was lowest for T13 followed by T10, T6, L1 and S3 with no significant effect of speed at T6, T10 and T13. Inertial sensor displacement and symmetry data showed acceptable accuracy and good levels of consistency for back movement. The small mediolateral movement amplitude means that changes of <25% in mediolateral amplitude (also unlikely to be detected by visual assessment) may go undetected. New sensor generations with improved sensor sensitivity and ease of use of equipment indicate good potential for use in a field situation. © 2010 EVJ Ltd.

  9. Rabbit colony infected with a bovine-like G6P[11] rotavirus strain.

    PubMed

    Schoondermark-van de Ven, Esther; Van Ranst, Marc; de Bruin, Wieke; van den Hurk, Patrick; Zeller, Mark; Matthijnssens, Jelle; Heylen, Elisabeth

    2013-09-27

    Group A rotaviruses (RVAs) are the main etiological agent of infantile diarrhea in both humans and animals worldwide. A limited number of studies have investigated the molecular characteristics of RVA strains in stool specimens of rabbits, with only a few lapine RVA strains isolated and (partially) characterized to date. The most common G/P-genotype combinations found in rabbits are G3P[14] and G3P[22]. In this study a RVA strain was isolated from the small intestine of a 9-week-old rabbit from an infected laboratory rabbit colony. The RVA strain RVA/Rabbit-tc/NLD/K1130027/2011/G6P[11] was shown to possess the typical bovine G6 and P[11] genotypes. The complete genome of this unusual lapine strain was sequenced and characterized. Phylogenetic analyses of all 11 gene segments revealed the following genotype constellation: G6-P[11]-I2-R2-C2-M2-A13-N2-T6-E2-H3. The VP1, VP2, VP3, VP6, NSP2 and NSP4 genes all belonged to DS-1-like genotype 2, but clustered more closely to bovine RVA strains than to lapine RVA strains. The NSP1 genotype A13 is typically associated with bovine RVAs, while the NSP3 genotype T6 and the NSP5 genotype H3 have been found in a wide variety of species. However, the isolated strain clustered within bovine(-like) T6 and H3 subclusters. Overall, the data indicate that the RVA strain is most closely related to bovine-like RVA strains and most likely represents a direct interspecies transmission from a cow to a rabbit. Altogether, these findings indicate that a RVA strain with an entirely bovine genome constellation was able to infect and spread in a laboratory rabbit colony. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Hesperetin derivative-7 inhibits PDGF-BB-induced hepatic stellate cell activation and proliferation by targeting Wnt/β-catenin pathway.

    PubMed

    Lin, Xiang; Kong, Ling-Na; Huang, Cheng; Ma, Tao-Tao; Meng, Xiao-Ming; He, Yong; Wang, Qian-Qian; Li, Jun

    2015-04-01

    Liver fibrosis results from a continuous wound-healing response of the liver to repeated injury. Hesperidin (HDN) is a naturally occurring flavanone glycoside, which is extracted from fruit peels of the genus citrus. Previous studies focused on the anti-inflammation, anti-tumor and anti-oxidant roles of HDN. However, the role of HDN in hepatic fibrosis is still unknown. Here, we evaluated the role of HDND-7, a derivative of HDN which has better water solubility and bioavailability, in the activation and proliferation of PDGF-BB-induced hepatic stellate cells (HSCs), then we investigated the anti-fibrotic effect of HDND-7 in CCl4-induced mouse model of liver fibrosis. The study aimed to determine whether HDND-7 could affect the survival of HSC-T6 in vitro, while evaluating its anti-fibrotic efficacy on CCl4-induced liver fibrosis in Kunming mice. Our results revealed that HDND-7 inhibited the proliferation and activation of PDGF-BB-treated HSC-T6 cells in a time- and dose-dependent manner. In addition, administration of HDND-7 significantly attenuated liver fibrosis, as evident by the dramatic down-regulation of α-smooth muscle actin (α-SMA) and type I collagen alpha-1 (Col1α1) in both mRNA and protein levels in vivo and in vitro. Furthermore, we also found that HDND-7 decreased the expression of β-catenin and the downstream proteins, cyclind1 and C-myc, indicating that HDND-7 may inhibit the activation and proliferation of PDGF-BB-induced HSC-T6 and attenuate liver fibrosis, at least in part, through targeting the Wnt/β-catenin signaling pathway. Hence HDND-7 might be employed as a promising natural supplement for liver fibrosis drug therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Effects of hot extrusion and heat treatment on microstructure and properties of industrial large-scale spray-deposited 7055 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yang, Yonggang; Zhao, Yutao; Kai, Xizhou; Zhang, Zhen; Zhang, Hao; Tao, Ran; Chen, Gang; Yin, Houshang; Wang, Min

    2018-01-01

    The industrial large-scale 7055 aluminum alloy fabricated by spray forming technology was subjected to hot extrusion and heat treatment to achieve high strength and ductility. Microstructure of the as-deposited alloy indicates that higher density billets with equiaxed grains (20–40 μm) were fabricated rather than a typical dendritic microstructure of the as-cast alloy. The grains of the as-extruded alloy exhibit fibrous morphology, the original boundaries disappear and fined second phases with size about 0.5–5 μm distribute along with extrusion direction. Meanwhile, the defects could be eliminated by hot extrusion, which resulted in good strength as well as ductility. The ultimate tensile strength, yield strength and elongation of the as-extruded alloy are 345 MPa, 236 MPa and 18.5%, respectively. After heat treatment, the partial recrystallization is observed around the un-recrystallized grains and sub-grains. And the platelet/rod-shaped precipitates (MgZn2) show a uniform distribution in the matrix alloy. The alloy reaches the maximum tensile strength of 730 MPa after T6 temper treatment, associated with a fine precipitation (MgZn2). However, with further deepen aging degree (from T6 to T73 temper), the size of dominant precipitated phases (MgZn2) grows obviously, the grain boundary precipitates transform from continuous to individual ones and the width of precipitate free zone increases. The result shows that the alloy after T7X temper treatment exhibits higher electrical conductivity (>35 %IACS) and facture toughness (>25.6 MPa m1/2) although a 8%–17% reduction in strength compared with that at T6 temper.

  12. Atmospheric Turbulence Research at DFVLR

    DTIC Science & Technology

    1988-07-01

    moyens de recherche employcs, qui comprennent des aeronefs dquipds d’instruments et des modeles numeiques. Quelques rdsultats de recherche sur les...des applications de ces resultats a I’etude de la r~ponse des aeronefs et de leurs structures aux contraintes de la turbulence. Le rapport a 6t6...presente au sous-comit pour le vol des aeronefs a structure non-igide en milieu turbulent, presidi par le Dr G-Coupry. IIi IM0UO iUC iUIaJZ kA CIVIR Anm M

  13. Hypervelocity Impact Analysis of International Space Station Whipple and Enhanced Stuffed Whipple Shields

    DTIC Science & Technology

    2004-12-01

    4.826 mm) Al2219-T87 Rear Wall 0.04” (1.016 mm) Al2024 -T3 Witness Plate 4.5” Front to Back 3” Gap from Back of Rear Wall to Front of...Witness Plate 0.08” (2.032 mm) Al6061-T6 Bumper 0.19” (4.826 mm) RW Al2219-T87 Rear Wall 0.04” Al2024 -T3 Witness Plate 6 Layers of Nextel AF62, 6

  14. ERG (Electroretinogram) Implicit Time: An Exploration of High Frequency Wavelets Recorded in the Human Visual System.

    DTIC Science & Technology

    1983-10-15

    the le syst~me visuel de IPanimal, ainsi que dans l’ERG earliest cortical processing of visual information. de I’homme. Elkes ont galement t6...40 msec apres l’installation dTun flash de stereotypic wavelet repetition rate permnitted the 10" trolands. d’angle visuel de 25’. et 100 msec de use... Perception . Wiley. New York. 257-266. 1965. Siefried. J.B. Early potentials evoked by macuslar stimulation: * Harding. G.F.A. and Rubenstein. M.P. The scalp

  15. Methods of Cost Reduction for United States Coast Guard Telephone Systems.

    DTIC Science & Technology

    1981-03-01

    AD-Alil 182 NAVAL POSTGRADUATE SCHOOL MONTEREY CA F/6 17/2 METHODS OF COST REDUCTION FOR UNITED STATES COAST GUARD TELEPHO--ETC CU) UNLSIID MAR Al R...Monterey, California act Ak;--LE-CTED THESIS METHODS OF COST REDUCTION FOR UNITED STATES COAST GUARD TELEPHONE SYSTEMS by Russell N. Terrell March 1931...MR41 WSu10) . TyPS OP miPOmT 6 pmo0 CavgmgO Methods of Cost Reduction for United Master’s Thesis; States Coast Guard Telephone Systems March 1981 6

  16. Epicrestal and subcrestal placement of platform-switched implants: 18 month-result of a randomized, controlled, split-mouth, prospective clinical trial.

    PubMed

    Froum, Stuart J; Cho, Sang-Choon; Suzuki, Takanori; Yu, Paul; Corby, Patricia; Khouly, Ismael

    2018-02-23

    To evaluate the changes in marginal bone levels (MBL) and soft tissue dimension around platform-switched implants with the implant-abutment junction (IAJ) placed at the crest or 1.5-2 mm subcrestally. In all, 96 platform-switched implants were placed in either the posterior maxilla or mandible in 48 partially edentulous patients in a split-mouth study. All implants were provisionally restored after 4-5 months and definitively after 6 months (T6). Radiographic assessment of MBL was assessed at implant placement (T0), T6, 12 months (T12), and 18 months (T18) after placement. Mid-buccal soft tissue and papilla measurements were performed at T6, T12, and T18. In all, 43 patients with 86 implants completed the study. The T18 examination showed an implant survival rate of 100% in both groups. Analysis showed that MBL varied as a function of IAJ location, which indicated more coronal bone levels with subcrestal (2.39 ± 0.08 mm) than with epicrestal placements (0.88 ± 0.08 mm) (p < .05). Greater average marginal bone loss was found in the subcrestal group (0.40 ± 0.07 mm) compared to the epicrestal group (0.13 ± 0.08 mm) although no statistically significant difference was found at T18 (p > .05). Levels of mid-buccal soft tissue had no significant changes over time, regardless of group (p > .05). There was a significant difference in increase in papilla between T6 and T12 and T18 (p = .005 and .001), but not between T12 and T18 (p = .61). These papilla levels and changes were similar between groups (p > .05). The MBL changes around platform-switched implants with same geometry were not affected by the epicrestal or subcrestal location of the IAJ. Furthermore, the location of the IAJ did not affect the implant survival and soft tissue dimensions. However, no bone loss was located apical to the IAJ when the implants were placed subcrestally. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Photophysics of Laser Dyes in Aqueous Polymer Media

    DTIC Science & Technology

    1991-06-30

    8217)-C-CH 2, 3.3, q, 4H, N-CH 2-, 2.3, s, 3H, C(4)-CH3, 1.1, t, 6H , N-C-CH3 . Synthesis and characterization of the conjugate of PMAA and coumarin ...included the study of the effects of unusual medium on the fluorescence properties of a series of coumarin laser dyes. Special attention was given to...susceptible to photodegradation since they are sequestered in polymer interiors away from adventitious quenchers. Comparison was made in the study of coumarin

  18. Icaritin induces cell death in activated hepatic stellate cells through mitochondrial activated apoptosis and ameliorates the development of liver fibrosis in rats.

    PubMed

    Li, Jing; Liu, Peng; Zhang, Ruixiu; Cao, Lu; Qian, Haihua; Liao, Jian; Xu, Wen; Wu, Mengchao; Yin, Zhengfeng

    2011-09-01

    Icaritin is an active ingredient extracted from the plant Herba Epimedium Sagittatum (Sieb. et Zucc.) Maxim. The purpose of this study is to investigate the effects and mechanisms of icaritin-induced cell death in activated hepatic stellate cells (HSCs) and ameliorating the development of liver fibrosis in rats. : In vitro, icaritin-induced cell death rates in HSC-T6 (rat) and LX-2 (human) HSC lines as well as normal hepatocyte cell lines HL-7702 (L02) and WRL-68 were assayed by MTT method, and the apoptotic ratios were detected by both flow cytometry and the Annexin-V-FITC Apoptosis Detection Kit. A Whole Rat Genome Microarray Kit was used to identify expression of interest genes through fold-change screening. In vivo study, experimental liver fibrosis models were built by carbon tetrachloride (CCl(4)) or common bile duct ligation (CBDL) in Wistar rats. Icaritin (1mg/kg/day, three days a week) was administered by gastric gavage for four weeks (n=6 per group). At the end of the study, serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) as well as the contents of hydroxyproline and collagen I in liver tissues were measured. Histopathological changes and the distribution of activated HSCs were observed in the liver tissues using hematoxyline-eosin (HE) staining and immunohistochemical staining for α-smooth muscle actin (α-SMA). Icaritin induced apoptosis in HSC-T6 and LX-2 in a concentration- and time-dependent manner with little toxicity to normal hepatocyte cell lines. The IC(50) of icaritin in HSC-T6 was 12.83 μM at 48 h. Apoptotic ratio of HSC-T6 treated with 24 μM icaritin was 20.19%, and the G2 phase of the cell cycle did not occur (P<0.05). Gene analysis showed that icaritin up-regulated Bak-1, Bmf and Bax expression while significantly down-regulated Bcl-2 expression (vs. control group, P<0.01). These results suggested that mitochondrial pathway played an important role in icaritin-induced apoptosis in activated HSCs. In vivo

  19. Atmospheric Fluctuations Which Lead to Trackable Radar Signals in the Marine Boundary Layer.

    DTIC Science & Technology

    1981-07-01

    Eq. (3.14) should be replaced by the Kadomtsev -Petviashvili equation, 36 (uT + 6 uux + UXXX) + Unn 0 , (3.15) where n is measured along the crest of...the wave (e.g., see Kadomtsev and Petviashvili, 1970; or Ablowitz and Segur, 1979). Other balances are possible as well. Equations (3.14) and (3.15) are...R., (197z); "Atmospheric Gravity Waves from Winds and Storms", J. Atmos. Sci. 29, 445-456. Kadomtsev , B. B., and Petviashvili, V. I., (1970); "On the

  20. Line soliton interactions of the Kadomtsev-Petviashvili equation.

    PubMed

    Biondini, Gino

    2007-08-10

    We study soliton solutions of the Kadomtsev-Petviashvili II equation (-4u(t)+6uu(x)+3u(xxx))(x)+u(yy)=0 in terms of the amplitudes and directions of the interacting solitons. In particular, we classify elastic N-soliton solutions, namely, solutions for which the number, directions, and amplitudes of the N asymptotic line solitons as y-->infinity coincide with those of the N asymptotic line solitons as y-->-infinity. We also show that the (2N-1)!! types of solutions are uniquely characterized in terms of the individual soliton parameters, and we calculate the soliton position shifts arising from the interactions.

  1. Three-Dimensional Finite-Element Analysis of Layered Composite Structures.

    DTIC Science & Technology

    1982-07-01

    at time t + At as: where fEL ,. [lL) and JR1 are the linear stiffnes matrix, ionlinear stiffness matrix and usbaLaaced t4at. t4dt 6 -f ted t , 6u .. t...ment. Por a (12)b quarter plate these Imply For example, consider 8% 3#01, At x, -0: u 1 -0. tyft0, t3 .f0 j. % d1 dx -3𔃻" I a E (16) (a) 1 3_ 1d - 1

  2. Breaching of Obstacles (An Engineer Assessment Methodology).

    DTIC Science & Technology

    1985-06-01

    Bridging--Continued Class 60 Float Bridge Construction : Time Estimates Wr T < 27.4 Wr * 27.-4 > 27.4 I + Wr - 27.4 Number of Floats = Wr + 10% 3...and ROKA Only) Ribbon Bridge Construction (USA Only): T = Wr 150 Number of Interior Bays = Wr - 14 6.7 Ribbon Bridge Section Crew 25 Interior Bays 5...Ramp Bays 2 Erection Boats 3 M4T6 Float Bridge Construction : T = Wr 75 W r Number of Floats = Wr + 10% 3 Assembly Sites Required Wr Number of Sites

  3. Advanced Glycation End Products Evolution after Pancreas-Kidney Transplantation: Plasmatic and Cutaneous Assessments

    PubMed Central

    Oliveira, José C.; Vizcaíno, José Ramón; Gouveia, Carlos; Silva, Donzília; Henriques, António C.; Noronha, Irene L.; Rodrigues, Anabela

    2016-01-01

    Diabetes mellitus leads to increased Advanced Glycation End Products (AGE) production, which has been associated with secondary diabetic complications. Type 1 diabetic patients undergoing pancreas-kidney transplantation (SPKT) can restore normoglycemia and renal function, eventually decreasing AGE accumulation. We aimed to prospectively study AGE evolution after SPKT. Circulating AGE were assessed in 20 patients, at time 0 (T0), 3 months (T3), 6 months (T6), and 12 months (T12) after successful SPKT. Global AGE and carboxymethyllysine (CML) were analyzed, as well as advanced oxidation protein products (AOPP). Skin biopsies were obtained at T0 and T12. Immunohistochemistry with anti-AGE antibody evaluated skin AGE deposition. AGE mean values were 16.8 ± 6.4 μg/mL at T0; 17.1 ± 3.8 μg/mL at T3; 17.5 ± 5.6 μg/mL at T6; and 16.0 ± 5.2 μg/mL at T12. CML mean values were 0.94 ± 0.36 ng/mL at T0; 1.11 ± 0.48 ng/mL at T3; 0.99 ± 0.42 ng/mL at T6; and 0.78 ± 0.38 ng/mL at T12. AOPP mean values were 130.1 ± 76.8 μMol/L at T0; 137.3 ± 110.6 μMol/L at T3; 116.4 ± 51.2 μMol/L at T6; and 106.4 ± 57.9 μMol/L at T12. CML variation was significant (P = 0.022); AOPP variation was nearly significant (P = 0.076). Skin biopsies evolved mostly from a cytoplasmic diffuse to a peripheral interkeratinocytic immunoreaction pattern; in 7 cases, a reduction in AGE immunoreaction intensity was evident at T12. In conclusion, glycoxidation markers decrease, plasmatic and on tissues, may start early after SPKT. Studies with prolonged follow-up may confirm these data. PMID:26881017

  4. 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

  5. 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.

  6. Test Excavation and Evaluation of 45-FR-317, on the Middle Columbia River, Near Pasco, Washington.

    DTIC Science & Technology

    1984-01-01

    1934 3ldg. 60?, City-County Airport 13. NUMSEROF PAGES .4alla ’Nalla, 1.ashington 99362 44 14. m.)NiTO5RI t6 AG LN C NAME &6ADE~ H Si f~. ff-, Co r4liog...ranged in age from circa 6,000 years B.C., and possibly earlier (Rice 1967), to historic times" (Cleveland 1976:3). 𔃻 .. . ! I ! " .. . . ’ . . . . 2...present in the area, the most important of which, for humans, were chinook salmon ( Oncorhynchus tshawtscha), coho salmon (0. kisutch), and steelhead

  7. Real Time Programs: Design Implementation of Validation: A Survey.

    DTIC Science & Technology

    1987-04-01

    Syachroiew 3 Flgure 2.5: Di.II6uted partial coda’ syncmcoaar. P. pp.p Global Syiicbroniner tl el t4 t 3 *p PP.* P411A * P. At tls T4 t 93 e3 t6 Syacbmaiser...the definition of the envuronment is of crucial importance. The development envuoument inclu"desth proce. so used, the operating system, the language...on its private memory. 3. Some data constructs are located in the system shared memory. 4. Each task descriptor consists of two parts: global and

  8. Magnetic reversal dynamics of NiFe-based artificial spin ice: Effect of Nb layer in normal and superconducting state

    NASA Astrophysics Data System (ADS)

    Kaur, M.; Gupta, Anurag; Varandani, D.; Verma, Apoorva; Senguttuvan, T. D.; Mehta, B. R.; Budhani, R. C.

    2017-11-01

    Square arrays of artificial spin ice (ASI) constituting weakly interacting NiFe nano-islands, with length ˜312 nm, width ˜125 nm, thickness ˜20 nm, and lattice constant ˜570 nm, were fabricated on Nb thin film and on thermally grown 300 nm SiO2 on silicon. Detailed investigations of magnetic force microscopy (MFM) at room temperature, and magnetization M(H) loops and relaxation of remanent magnetization (Mr) at various temperatures were carried out in two in-plane field geometries, namely, parallel ("P"-parallel to the square lattice) and diagonal ("D"- 45° to the square lattice). The magnetic response of the ASI samples shows striking difference for insulating (SiO2), metallic (Nb, T > 6.6 K) and superconducting (Nb, T < 6.6 K) bases, and the field geometry. For instance, with the Nb base in the normal metallic state (T > 6.6 K), (1) in "P" geometry the M(H) loops are found to be more "S" shaped in comparison with that for SiO2 base; (2) the ratio of magnetic vertex population of Type II to Type III vertices extracted from MFM studies in "P"("D") geometry is ˜1:1.1(1.2:1) that changed for the SiO2 base to ˜2.1:1 (4: 1). However, the NiFe-ASI on both metallic Nb and SiO2 bases exhibit a highly athermal decay of magnetization, and the % change in Mr in about two hours at T = 10 K (300 K) lies in a range of ˜1.07-1.80 (0.25-0.62). With Nb base in superconducting state (T < 6.6 K), the M(H) loops not only look radically different from those with SiO2 and metallic Nb as bases but also show significant difference in "P" and "D" geometries. These results are discussed in terms of inter-island magnetostatic energy as influenced by field geometry, presence of metallic Nb base and competing vortex pinning energy of superconducting Nb base.

  9. Maumee Bay State Park, Ohio. Shoreline Erosion Beach Restoration Study. Final Feasibility Report and Final Environmental Impact Statement. Interim to Western Lake Erie Shore Study. Volume 1. Main Report. Revised.

    DTIC Science & Technology

    1983-12-01

    00N Benelopment n 1.133.000 0,154.000 ,110,000 5,085,000 6.23,000 , Economie Efficieney I (l) Not aseal Benfits - 6,703.500 t 6.69L.100 6.716.100...the seven species collected, yellow bullhead, white bass, and yellow perch, are fish of sport and/or commercial value. A slight increase in species...habitat and thereby the local sport fishery, boat-fishing opportunities may also be enhanced. Alternative 5 would facilitate a lesser degree of park

  10. USU AFOSR University Engineering Design Challenge Proposal

    DTIC Science & Technology

    2015-01-02

    22‐Feb TMI Epoxy $107.82 19‐FebHome Depot Foam board, acetone $41.68 23‐FebHome Depot Sandpaper, lumber, paint  liner $51.87 4‐MarHD Supply White Cap...Lifters 3 Design Solution Telescopic Hydraulic Cylinder & Carbon Fiber Base Aggie Life Lifters 4 12/28/2014 3 Deployment 1 2 3 Aggie Life Lifters 5... Cylinder Custom Columbus Jack 3 Stage Ram 10,000 psi Aggie Life Lifters 6 12/28/2014 4 Base Assembly Pivot Design 6061-T6 AL Flanged for carbon fiber

  11. Assessment of Motion Effects on the FPSO (Floating, Production, Storage and Offloading) Vessel Terra Nova

    DTIC Science & Technology

    2002-10-01

    sur le sommeil , les sympt6mes et la gravit6 du mal de mer et l’ex~cution des tdches a 6t6 effectu6 A divers moments dans le cours d’une p~riode de...partir des 911 questionnaires retourn~s, on a appris que les probli-mes assochis aux troubles de sommeil et aux sympt6mes du mal des transports pouvaient...tre qualifiis de l6gers A mod~r~s. Par contre, la correlation entre les troubles de sommeil et les mouvements du navire 6tait relativement 6lev~e. Le

  12. Compositions Fumigenes en Feuilles (Sheets of Smoke Composition),

    DTIC Science & Technology

    1979-07-01

    et la deformation sera permanente (on a un mat6riau plastique plut~t qu’~lastique). De plus, le mat~riau possade encore des groupements n’ayant pas...est plus 6lev6e 1 22.8 C. Les 6chantillons .1 cette derni~ re temp6rature ont donc 6t6 plus exposes 1 l’humidit6, ce qui peut Ztre la cause d’un...sous forme de feuilles flexibles et minces. Cette composition, de type composite a base de liant polym ~rique et produisant une fum~e blanche, offre

  13. On the Support of Diffusion Processes with Applications to the Strong Maximum Principle

    DTIC Science & Technology

    1972-01-01

    definite. The idea is to reduce the martingale problem to a stochastic differential equation which can be solved by the techniques introduced by K. 1t6 in...see that supp(P0) contains all differentiable paths which start at 0. Because these are dense in Q0, equation (3.4) is now proved. We have therefore...Math. and Mech., Vol. 20 (1970). pp. 213-228. [4] K. IT6, "On stochastic differential equations ," Mem. Amer. Math. Soc., No. 4 (1951). [5] H. P. McKEAN

  14. Diffusion Processes

    DTIC Science & Technology

    1972-01-01

    least two other possible ways of constructing diffusion processes for given coefficients. If we use the stochastic differential equations of 1t6, we take...stochastic differential equation . Another possibility is to use the theory of partial differential equations . We consider the fundamental solution p(s, x, t, y...a matrix u(t. x) such that (1.3) a(t, x)a*(t, x) = a(t, x). If /3(t) is Brownian motion in d dimensions, one can set up the stochastic differential

  15. Atmospheric/Ionospheric/Magnetospheric Research Using the Chatanika Radar.

    DTIC Science & Technology

    1980-01-31

    Rocket support; Wideband satellite pass 761124 0802-1053 Rocket support 761126 0843-1119 Rocket support PF-HJNH-124 launch 1025 761127 0727-1126...2240 S3-3 satellite pass 2207 770119 1929-2039 Wideband satellite pass 770126 0138-0815 Electric fields (plasmapause) 0937- 1025 21 Time Date Start-End...770207 0316-0552 Rocket support PF-NT-127 launch 0451 770209 0301-04.49 Rocket support 770210 0247 -04,t6 Rocket support 770210 0944-1105 Wideband

  16. International Conference on Millimeter Wave and Far-Infrared Technology (1st) Held in Beijing, China, August 17-21, 1992

    DTIC Science & Technology

    1993-03-01

    A.F. Krjpnov. TeCtioiogy of Chn~o. Chengdu, P.R. China Insliftute of Applied Physics . Academy ofBra Scoences of Rusiea. 603600 N&zhy Novgorod...University at Science and Tec*,noogy of China , HeOW, P.A. China T6.6 ’IKa-Band Gunn VCOse. Cheng )Q U. the Insitmt of Electronic Engineering of PLA. and Yong...Krupnov Radiophysical Research Institute Institute of Applied Physics Russian Academy of Sciences Nizhny Novgorod, 603600, Russia ABSTRACT In this paper

  17. Bridge Fatigue Monitoring Device

    DTIC Science & Technology

    1990-11-01

    0 U0 7/ z io 1 00 *00 • - /A• / S~ e 2219 - T87 3 0 54 56-H321 v/0 loo <• . 1 6061i- T6 5 𔃺 7005 -T63 S7106-T63 LID / ,%::, iO: 20 50 O00 e 2219 - T8...areas in military bridges such as welds , bolt or rivet holes and hinges. Vehicles crossing over the bridge produce a single major stress cycle at any...Chapter 3. 6. Schilling, C.G., K.H. Klippstein, J.M. Barsom and G.T. Blake, "Fatigue of welded Steel Bridge Members under Variable-Amplitude Loadings

  18. Damage Tolerance Assessment Handbook. Volume 1. Introduction Fracture Mechanics Fatigue Crack Propagation

    DTIC Science & Technology

    1993-10-01

    a 2219 - T87 _o 5456-H321 t- o 6061- T651 9 7005-T63 ,/ 7039-T6 X 31 o/ v 7106- T63 10- 0 (A/K) 10 0- 9 I _ I L I 10 20 50 IO0 STRESS-INTENSITY...of the welded Liberty ships constructed in the United States. Of the 4694 ships constructed, 1289 experienced brittle fracture of the hull and 233 of...specifically at the Welding Institute. The chief purpose was to find a characterizing parameter for welds and welded components of structural steels. A

  19. A Survey of High Explosive-Induced Damage and Spall in Selected Metals Using Proton Radiography

    NASA Astrophysics Data System (ADS)

    Holtkamp, D. B.; Clark, D. A.; Ferm, E. N.; Gallegos, R. A.; Hammon, D.; Hemsing, W. F.; Hogan, G. E.; Holmes, V. H.; King, N. S. P.; Liljestrand, R.; Lopez, R. P.; Merrill, F. E.; Morris, C. L.; Morley, K. B.; Murray, M. M.; Pazuchanics, P. D.; Prestridge, K. P.; Quintana, J. P.; Saunders, A.; Schafer, T.; Shinas, M. A.; Stacy, H. L.

    2004-07-01

    Multiple spall and damage layers can be created in metal when the free surface reflects a Taylor wave generated by high explosives. These phenomena have been explored in different thicknesses of several metals (tantalum, copper, 6061 T6-aluminum, and tin) using high-energy proton radiography. Multiple images (up to 21) can be produced of the dynamic evolution of damaged material on the microsecond time scale with a <50 ns "shutter" time. Movies and multiframe still images of areal and (Abel inverted) volume densities are presented. An example of material that is likely melted on release (tin) is also presented.

  20. A SURVEY OF HIGH EXPLOSIVE-INDUCED DAMAGE AND SPALL IN SELECTED METALS USING PROTON RADIOGRAPHY.

    SciTech Connect

    Holtkamp, D. B.; Clark, D. A.; Ferm, E. N.; Gallegos, R. A.; Hammon, D.; Hemsing, W. F.; Hogan, G. E.; Holmes, V. H.; King, N.. S.P; liljestrand, R.; Lopez, R. P.; Merrill, F. E.; Morris, C. L.; Morley, K. B.; Murray, M. M.; Pazuchanics, P. D.; Prestridge, K. P.; Quintana, J. P.; Saunders, A.; Schafer, T.; Shinas, M. A.

    2003-07-01

    Multiple spall and damage layers can be created in metal when the free surface reflects a Taylor wave generated by high explosives. These phenomena have been explored in different thicknesses of several metals (tantalum, copper, 6061 T6-aluminum, and tin) using high-energy proton radiography. Multiple images (up to 21) can be produced of the dynamic evolution of damaged material on the microsecond time scale with a <50 ns “shutter” time. Movies and multiframe still images of areal and (Abel inverted) volume densities are presented. An example of material that is likely melted on release (tin) is also presented..