Resource recovery of WC-Co cermet using hydrothermal oxidation technique

International Nuclear Information System (INIS)

Gao Ningfeng; Inagaki, F.; Sasai, R.; Itoh, H.; Watari, K.

2005-01-01

WC-Co cermet is widely used in industrial applications such as cutting tools, dies, wear parts and so on. It is of great importance to establish the recycling process for the precious metal resources contained in WC-Co cermet, because all these metals used in Japan are imported. In this paper we reported a hydrothermal oxidation technique using nitric acid for the reclamation of WC and Co. The WC-Co cermet specimens with various WC particle sizes and Co contents were hydrothermally treated in HNO 3 aqueous solutions at temperatures of 110-200 C for durations of 6-240 h. The Co was preferentially leached out into the acidic solution, while the WC was oxidized to insoluble WO 3 hydrate which was subsequently separated by filtration. The hydrothermal treatment parameters such as solvent concentrations, treatment temperatures, holding time were optimized in respect to different kinds of WC-Co cermets. A hydrothermal oxidation treatment in 3M HNO 3 aqueous solution at 150 C for 24 h was capable of fully disintegrating the cermet chip composed of coarse WC grains of 1-5 μm in size with 20 wt% of Co as binder. While the more oxidation resistant specimen composed of fine WC grains of 0.5-1.0 μm in size with 13 wt% of Co, was completely disintegrated by a treatment in 7 M HNO 3 aqueous solution at 170 C for 24 h. The filtered solid residues were composed of fine WO 3 .0.33H 2 O powder and a small amount of WO 3 . The recovered WO 3 .0.33H 2 O powder can be easily returned to the industrial process for the synthesis of WC powder so that the overall recycling cost can be possibly lowered. (orig.)

Atomic layer deposition synthesis and evaluation of core–shell Pt-WC electrocatalysts

International Nuclear Information System (INIS)

Hsu, Irene J.; Chen, Jingguang G.; Jiang, Xiaoqiang; Willis, Brian G.

2015-01-01

Pt-WC core shell particles were produced using atomic layer deposition (ALD) to deposit Pt layers onto WC particle substrates. A range of Pt depositions were used to determine the growth mechanism for the Pt-WC powder system. TEM imaging and Cu stripping voltammetry found that Pt ALD growth on WC powder substrates was similar to that on WC thin films. However, excess free carbon was found to affect Pt ALD by blocking adsorption sites on WC. The Pt-WC samples were evaluated for the oxygen reduction reaction using a rotating disk electrode to obtain quantitative activity information. The mass and specific activities for the 30 and 50 ALD cycle samples were found to be comparable to a 10 wt. % Pt/C catalyst. However, higher overpotentials and lower limiting currents were observed with ALD Pt-WC compared to Pt/C catalysts, indicating that the oxygen reduction mechanism is not as efficient on Pt-WC as on bulk Pt. Additionally, these Pt-WC catalysts were used to demonstrate hydrogen evolution reaction activity and were found to perform as well as bulk Pt catalyst but with a fraction of the Pt loading, in agreement with the previous work on Pt-WC thin film catalysts

Microstructure, Wear Behavior and Corrosion Resistance of WC-FeCrAl and WC-WB-Co Coatings

Directory of Open Access Journals (Sweden)

Janette Brezinová

2018-05-01

Full Text Available The paper is focused on investigating the quality of two grades of thermally sprayed coatings deposited by high-velocity oxygen fuel (HVOF technology. One grade contains WC hard particles in an environmentally progressive Ni- and Co-free FeCrAl matrix, while the second coating contains WC and WB hard particles in a cobalt matrix. The aim of the experimental work was to determine the effect of thermal cyclic loading on the coatings’ resistance to adhesive, abrasive and erosive wear. Abrasive wear was evaluated using abrasive cloth of two grit sizes, and erosive wear was evaluated by a dry-pot wear test in a pin mill at two sample angles. Adhesion wear resistance of the coatings was determined by a sliding wear test under dry friction conditions and in a 1 mol water solution of NaCl. Corrosion resistance of the coatings was evaluated using potentiodynamic polarization tests. Metallographic cross-sections were used for measurement of the microhardness and thickness and for line energy-dispersive X-ray (EDX analysis. The tests proved the excellent resistance of both coatings against adhesive, abrasive, and erosive wear, as well as the ability of the WC-WB-Co coating to withstand alternating temperatures of up to 600 °C. The “green carbide” coating (WC-FeCrAl can be recommended as an environmentally friendly replacement for Ni- and Co-containing coatings, but its operating temperature is strictly limited to 500 °C in air.

The Nature of Bonding in WC and WN

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

The nature of bonding in the title compounds has been studied by using CASSCF and FOCl techniques. The ground states of WC and WN are found to be 3Δ and 4∑- state arising primarily from:...1σ2σ21π41δ13σ1 and ...1σ2σ21π41δ23σ1 configuration respectively. WC shows a strong character of covalent bond while WN have obvious character of ionic bond and the dissociation energy of WN is larger than that of WC (6.15 and 5.41 eV respective).

Wear resistance and fracture mechanics of WC-Co composites

International Nuclear Information System (INIS)

Kaytbay, Saleh; El-Hadek, Medhat

2014-01-01

Manufacturing of WC-Co composites using the electroless precipitation method at different sintering temperatures of 1 100, 1 250, 1 350 and 1 500 C was successfully achieved. The chemical composition of the investigated materials was 90 wt.% WC with 10 wt.% Co, and 80 wt.% WC with 20 wt.% Co. The specific density, densification, and Vickers microhardness measurements were found to increase with increased sintering temperature for both the WC-Co compositions. The composites of tungsten carbide with 10 wt.% Co had a higher specific density and Vickers microhardness measurements than those for the composites of tungsten carbide with 20 wt.% Co. Composites with WC-10 wt.% Co had better wear resistance. The stress-strain and transverse rupture strength increased monotonically with the increase in sintering temperatures, agreeing with the material hardness and wear resistance behavior. Fractographical scanning electron microscopy analysis of the fracture surface demonstrated a rough characteristic conical shape failure in the direction of the maximum shear stress. A proposed mechanism for the formation of the conical fracture surface under compression testing is presented. (orig.)

Reactive Sintering of Bimodal WC-Co Hardmetals

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Marek Tarraste

2015-09-01

Full Text Available Bimodal WC-Co hardmetals were produced using novel technology - reactive sintering. Milled and activated tungsten and graphite powders were mixed with commercial coarse grained WC-Co powder and then sintered. The microstructure of produced materials was free of defects and consisted of evenly distributed coarse and fine tungsten carbide grains in cobalt binder. The microstructure, hardness and fracture toughness of reactive sintered bimodal WC-Co hardmetals is exhibited. Developed bimodal hardmetal has perspective for demanding wear applications for its increased combined hardness and toughness. Compared to coarse material there is only slight decrease in fracture toughness (K1c is 14.7 for coarse grained and 14.4 for bimodal, hardness is increased from 1290 to 1350 HV units.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7511

WC-3015 alloy (high-temperature alloy)

International Nuclear Information System (INIS)

Anon.

1974-01-01

WC-3015 Nb alloy containing 28 to 30 Hf, 1 to 2 Zr, 13 to 16 W, 0 to 4 Ta, 0 to 5 Ti, 0.07 to 0.33 C, less than or equal to 0.02 N, less than or equal to 0.03 O, less than or equal to 0.001 H was developed for use at high temperature in oxidizing environments. Its composition can be tailored to meet specific requirements. When WC-3015 is exposed to O at elevated temperature, Hf and Nb oxidized preferentially and HfO 2 dissolves in Nb 2 O 5 to form 6HfO-Nb 2 O 5 . This complex oxide has a tight cubic lattice which resists the diffusion of O into the substrate. During 24-h exposure to air at 2400 0 F, the alloy oxidizes to a depth of approximately 0.035 in. with a surface recession of 0 to 0.004 in. Oxidation resistance of WC-3015 welds and base material can be further enhanced greatly by applying silicide coatings. WC-3015 alloy can be machined by conventional and electrical-discharge methods. It can be hot worked readily by extrusion, forging or rolling. Cold working can be used at room or elevated temperature. It can be welded by the electron-beam or Tig processes. Physical constants, typical mechanical properties at 75 to 2400 0 F, and effects of composition and heat treatment on tensile and stress-rupture properties of the alloy are tabulated

Fracture toughness of a nanoscale WC-Co tool steel

International Nuclear Information System (INIS)

Densley, J.M.; Hirth, J.P.

1997-01-01

Tungsten carbide tool steels, comprising WC particles with 6.7--25wt% Co distributed in the interparticle regions as a quasi-continuous binder phase, can be considered as WC-Co composites. The fracture toughness of such WC-Co composites is dependent on the volume fraction, contiguity and thickness of the cobalt binder, and the size of the tungsten carbide grains. Research has shown that the ductile binder undergoes nearly all the plastic deformation during fracture, which provides the primary energy consuming process that enhances fracture resistance. Recent manufacturing developments have given rise to the production of a WC-6.7wt% Co cermet having an average WC grain size of 70 nm, with a corresponding binder mean thickness, h, of 9 nm calculated from d = h(1-V f )/V f where d = 70 nm and V f = 0.114. This composite has shown a higher wear resistance than that of conventional cermets in proportion to their hardness. Such improvement has been attributed to the difficulty in forming dislocations in the very small grains. There are also indications that the Co binder in the nanoscale cermet contains higher contents of dissolved W and C than for conventional scale cermets. Because plastic deformation is initially confined to the binder phase, it was of interest to perform mode 1 and mixed mode toughness tests on the nanoscale cermet to determine whether flow localization influenced mixed mode toughness as in bulk materials. Two generations of this cermet were provided by Rogers Tool Works. The first generation, A, had lower binder contiguity, with occasional agglomerations of WC grains. The second generation, B, was cleaner, with the cobalt binder more uniformly separating the WC grains

Micromechanics of fracture in WC-Co hardmetals

International Nuclear Information System (INIS)

Dusza, J.; Parilak, L.

1986-01-01

A study has been made in WC-Co cemented carbides with grain sizes of 2.1 - 3.6 μm and 13 - 32 vol% Co, of the relationship between the fracture toughness and microstructural parameters and micromechanisms of fracture. Regression analyses have been used to derive empirical relationships between fracture toughness, and the binder spacing, the contiguity and the relative proportions of fracture in the binder phase and between contiguous WC grains

Infrared processed Cu composites reinforced with WC particles

International Nuclear Information System (INIS)

Deshpande, P.K.; Li, J.H.; Lin, R.Y.

2006-01-01

Copper matrix composites with WC particle reinforcements have been prepared with an innovative infrared infiltration technique. The volume content of the reinforcement particles in the composite is about 53%. The relative composite density of as high as 99.9% has been obtained with this process. The electric conductivity of composites prepared in this study as determined by a four-point probe method, is similar to commercially available Cu/W composites containing 52 vol% tungsten. Microhardness, microstructure and wear resistance of the composites were also determined. The microstructure of Cu/WC composite reveals excellent wetting between the two constituent phases, WC and copper. The microhardness values of all completely infiltrated Cu/WC composites were in the range of 360-370 HV which is significantly higher than the microhardness of pure copper, 65 HV. Wear resistance of the composites was determined with a pin on disk wear test technique. The wear test results show that composites prepared in this study performed much better than those commercially available Cu/W composites by more than two-fold against silicon carbide abrasive disks

Ultra light weight jet engine JR100; Chokeiryo jet engine JR100

Energy Technology Data Exchange (ETDEWEB)

Matsuki, M. [Nippon Institute of Technology, Saitama (Japan)

1999-03-20

As a part of the jet lift V/STOL research by National Aerospace Laboratory, a study of trial manufacture of ultra light weight jet engine JR 100 started in FY 1964. The study was aimed at obtaining a lift engine for VTOL and founding the base for the future jet lift VTOL, and at taking in the results of the jet engine element study accumulated so far and manufacturing an advanced engine. Decided on the use of domestic materials for JR 100, the materials to be used are almost iron-based ones. Through the efforts for weight reduction in structure and processing, a thrust/weight ratio of 10 was realized. At the same time, the production/processing of light weight materials such as titanium alloys was proceeded with, and by adopting the materials to JR 200 system, a thrust/weight ratio of 15 was realized. Together with these, for the purpose of reducing the fuel consumption rate, studies started on fan for lift fan engine and high temperature turbine (an inlet temperature of 1250 degrees C was achieved), to get low noise/high efficiency fan. By the research results, the basis for jet lift VTOL was established, and it became the basis for the development of turbo fan engine FJR 710. (NEDO)

Hot isostatic pressing of nanosized WC-Co hardmetals

International Nuclear Information System (INIS)

Azcona, I.; Ordonez, A.; Sanchez, J.M.; Castro, F.; Dominguez, L.

2001-01-01

A new technique based on hot isostatic pressing (HIP) has been developed to produce dense nanosized WC-Co hardmetals without the addition of grain growth inhibitors. The glass encapsulation process is the key for the effective application of isostatic pressure at temperatures well below those usually required for reaching the closed porosity state in the WC-Co system. Fully dense WC-Co samples with cobalt contents ranging from 10 to 12 wt. % have been obtained by this technique at temperatures between 1000 o C and 1200 o C with 150 MPa of applied isostatic pressure for 30 minutes. The role of isostatic pressure on the activation of densification mechanisms is discussed. (author)

77 FR 61003 - Stephen C. Delaney, Jr.: Debarment Order

Science.gov (United States)

2012-10-05

...] Stephen C. Delaney, Jr.: Debarment Order AGENCY: Food and Drug Administration, HHS. ACTION: Notice... Cosmetic Act (the FD&C Act) debarring Stephen C. Delaney, Jr. for a period of 5 years from importing....35), finds that Mr. Stephen C. Delaney, Jr. has been convicted of a felony under Federal law for...

Development and kinetic analysis of cobalt gradient formation in WC-Co composites

Science.gov (United States)

Guo, Jun

2011-12-01

Functionally graded cemented tungsten carbide (FG WC-Co) is one of the main research directions in the field of WC-Co over decades. Although it has long been recognized that FG WC-Co could outperform conventional homogeneous WC-Co owing to its potentially superior combinations of mechanical properties, until recently there has been a lack of effective and economical methods to make such materials. The lack of the technology has prevented the manufacturing and industrial applications of FG WC-Co from becoming a reality. This dissertation is a comprehensive study of an innovative atmosphere heat treatment process for producing FG WC-Co with a surface cobalt compositional gradient. The process exploited a triple phase field in W-C-Co phase diagram among three phases (solid WC, solid Co, and liquid Co) and the dependence of the migration of liquid Co on temperature and carbon content. WC-Co with a graded surface cobalt composition can be achieved by controlling the diffusion of carbon transported from atmosphere during sintering or during postsintering heat treatment. The feasibility of the process was validated by the successful preparations of FG WC-Co via both carburization and decarburization process following conventional liquid phase sintering. A study of the carburization process was undertaken to further understand and quantitatively modeled this process. The effects of key processing parameters (including heat treating temperature, atmosphere, and time) and key materials variables (involving Co content, WC grain size, and addition of grain growth inhibitors) on the formation of Co gradients were examined. Moreover, a carbon-diffusion controlled kinetic model was developed for simulating the formation of the gradient during the process. The parameters involved in this model were determined by thermodynamic calculations and regression-fit of simulation results with experimental data. In summary, this research first demonstrated the principle of the approach

Phase size distribution in WC/Co hardmetal

International Nuclear Information System (INIS)

Roebuck, B.; Bennett, E.G.

1986-01-01

A high-resolution field emission scanning electron microscope was used to perform accurate quantitative metallography on a variety of WC/Co hardmetals. Particular attention was paid to obtaining the mean size and size distribution of the cobalt phase by linear analysis. Cobalt regions are frequently submicron and difficult to resolve adequately by conventional methods. The WC linear intercept distributions, and contiguity were also measured at the same time. The results were used to examine the validity of theoretic derivations of cobalt intercept size

The Particle Shape of WC Governing the Fracture Mechanism of Particle Reinforced Iron Matrix Composites.

Science.gov (United States)

Li, Zulai; Wang, Pengfei; Shan, Quan; Jiang, Yehua; Wei, He; Tan, Jun

2018-06-11

In this work, tungsten carbide particles (WC p , spherical and irregular particles)-reinforced iron matrix composites were manufactured utilizing a liquid sintering technique. The mechanical properties and the fracture mechanism of WC p /iron matrix composites were investigated theoretically and experimentally. The crack schematic diagram and fracture simulation diagram of WC p /iron matrix composites were summarized, indicating that the micro-crack was initiated both from the interface for spherical and irregular WC p /iron matrix composites. However, irregular WC p had a tendency to form spherical WC p . The micro-cracks then expanded to a wide macro-crack at the interface, leading to a final failure of the composites. In comparison with the spherical WC p , the irregular WC p were prone to break due to the stress concentration resulting in being prone to generating brittle cracking. The study on the fracture mechanisms of WC p /iron matrix composites might provide a theoretical guidance for the design and engineering application of particle reinforced composites.

Lightning Tests on the WC-130 Research Aircraft.

Science.gov (United States)

1982-12-01

in the WC-136 tests at various times.) E- Feild Fiber Optic Test Article Sensor Transmitter (Typ)WiePr Indtuced Voltag Sensor"" *Fiber I"=Current optic...well-characterized. 5.1 Skin Current Measurements Skin current vectors were measured at five fuselage locations on the left side of the WC-130 at a...MGL-S7) which were mounted so that they sampled two orthogonal components of the skin current vector . The measured responses were then inte- grated

Stellar C III Emissions as a New Classification Parameter for (WC) Central Stars

Science.gov (United States)

Feibelman, W. A.

1999-01-01

We report detection of stellar C III lambda 1909 emission in International Ultraviolet Explorer (IUE) echelle spectra of early-type [WC] planetary nebula central stars (CSPNs). Additionally, stellar C III emission at lambda 2297 is observed in early- and late-type [WC) CSPNS. Inclusion of these C III features for abundance determinations may resolve a conflict of underabundance of C/O for early type [WC2] - [WC4] CSPNS. A linear dependence on stellar C III lambda 2297 equivalent widths can be used to indicate a new classification of type [WCUV] central stars.

A. P. Sloan Jr. and leadership

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Paul Marinescu

2014-05-01

Full Text Available Organizing the manufacturing processes constituted probably the most difficult challenge in the American automotive industry in the 1920s. A. P. Sloan Jr. was one of the greatest captains of industry and shaped General Motors Corporation into the largest automotive manufacturer of the world. His creative approach on how to mix a degree of decentralized responsibility with centralized control remains a useful example for every corporate leader. The aim of our paper is to emphasize the contribution of Sloan Jr. to the development of leadership. The methodological approach is literature review.

Fabrication and evaluation of atmospheric plasma spraying WC-Co-Cu-MoS2 composite coatings

International Nuclear Information System (INIS)

Yuan Jianhui; Zhu Yingchun; Zheng Xuebing; Ji Heng; Yang Tao

2011-01-01

Research highlights: → Protective WC-Co-based coatings containing solid lubricant Cu and MoS 2 used in wear applications were investigated in this study. → It was found that the MoS 2 composition in the feed powder was kept in WC-Co-Cu-MoS 2 coatings, and the decomposition and decarburization of WC in APS process were improved. → Combining the wear resistance of WC with the lubricating properties of Cu and MoS 2 has an extremely beneficial effect on improving the tribological performance of the resulting coating. - Abstract: Protective WC-Co-based coatings containing solid lubricant Cu and MoS 2 used in wear applications were investigated in this study. These coatings were deposited on mild steel substrates by atmospheric plasma spraying (APS). The feedstock powders were prepared by mechanically mixing the solid lubricant powders and WC-Co powder, followed by sintering and crushing the mixtures to avoid different particle flighting trajectories at plasma. The tribological properties of the coatings against stainless steel balls were examined by ball-on-disk (BOD) tribometer under normal atmospheric condition. The microstructure of the coatings was studied by optical microscope, scanning electron microscope and X-ray diffraction. It was found that the MoS 2 composition in the feed powder was kept in WC-Co-Cu-MoS 2 coatings, and the decomposition and decarburization of WC in APS process were improved, which were attributed to the protection of Cu around them. The friction and wear behaviors of all the WC-Co-Cu-MoS 2 coatings were superior to that of WC-Co coating. Such behavior was associated to different wear mechanisms operating for WC-Co coating and the WC-Co-Cu-MoS 2 coatings.

Phase composition and microstructure of WC-Co alloys obtained by selective laser melting

Science.gov (United States)

Khmyrov, Roman S.; Shevchukov, Alexandr P.; Gusarov, Andrey V.; Tarasova, Tatyana V.

2018-03-01

Phase composition and microstructure of initial WC, BK8 (powder alloy 92 wt.% WC-8 wt.% Co), Co powders, ball-milled powders with four different compositions (1) 25 wt.% WC-75 wt.% Co, (2) 30 wt.% BK8-70 wt.% Co, (3) 50 wt.% WC-50 wt.% Co, (4) 94 wt.% WC-6 wt.% Co, and bulk alloys obtained by selective laser melting (SLM) from as-milled powders in as-melted state and after heat treatment were investigated by scanning electron microscopy and X-ray diffraction analysis. Initial and ball-milled powders consist of WC, hexagonal α-Co and face-centered cubic β-Co. The SLM leads to the formation of major new phases W3Co3C, W4Co2C and face-centered cubic β-Co-based solid solution. During the heat treatment, there occurs partial decomposition of the face-centered cubic β-Co-based solid solution with the formation of W2C and hexagonal α-Co solid solution. The microstructure of obtained bulk samples, in general, corresponds to the observed phase composition.

Dodecahedral W@WC Composite as Efficient Catalyst for Hydrogen Evolution and Nitrobenzene Reduction Reactions.

Science.gov (United States)

Chen, Zhao-Yang; Duan, Long-Fa; Sheng, Tian; Lin, Xiao; Chen, Ya-Feng; Chu, You-Qun; Sun, Shi-Gang; Lin, Wen-Feng

2017-06-21

Core-shell composites with strong phase-phase contact could provide an incentive for catalytic activity. A simple, yet efficient, H 2 O-mediated method has been developed to synthesize a mesoscopic core-shell W@WC architecture with a dodecahedral microstructure, via a one-pot reaction. The H 2 O plays an important role in the resistance of carbon diffusion, resulting in the formation of the W core and W-terminated WC shell. Density functional theory (DFT) calculations reveal that adding W as core reduced the oxygen adsorption energy and provided the W-terminated WC surface. The W@WC exhibits significant electrocatalytic activities toward hydrogen evolution and nitrobenzene electroreduction reactions, which are comparable to those found for commercial Pt/C, and substantially higher than those found for meso- and nano-WC materials. The experimental results were explained by DFT calculations based on the energy profiles in the hydrogen evolution reactions over WC, W@WC, and Pt model surfaces. The W@WC also shows a high thermal stability and thus may serve as a promising more economical alternative to Pt catalysts in these important energy conversion and environmental protection applications. The current approach can also be extended or adapted to various metals and carbides, allowing for the design and fabrication of a wide range of catalytic and other multifunctional composites.

Liquid Phase Sintering of (Ti,Zr)C with WC-Co.

Science.gov (United States)

Ma, Taoran; Borrajo-Pelaez, Rafael; Hedström, Peter; Blomqvist, Andreas; Borgh, Ida; Norgren, Susanne; Odqvist, Joakim

2017-01-11

(Ti,Zr)C powder was sintered with WC-Co following an industrial process, including an isotherm at 1410 °C. A series of interrupted sintering trials was performed with the aim of studying the sintering behavior and the microstructural evolution during both solid-state and liquid-state sintering. Reference samples, using the same elemental compositions but with the starting components TiC and ZrC instead of (Ti,Zr)C, were also sintered. The microstructure was investigated using scanning electron microscopy and energy dispersive X-ray spectroscopy. It is found that the (Ti,Zr)C phase decomposes into Ti-rich and Zr-rich nano-scale lamellae before the liquid-state of the sintering initiates. The final microstructure consists of the binder and WC as well as two different γ phases, rich in either Ti (γ₁) or Zr (γ₂). The γ₂ phase grains have a core-shell structure with a (Ti,Zr)C core following the full sintering cycle. The major differences observed in (Ti,Zr)C with respect to the reference samples after the full sintering cycle were the referred core-shell structure and the carbide grain sizes; additionally, the microstructural evolution during sintering differs. The grain size of carbides (WC, γ₁, and γ₂) is about 10% smaller in WC-(Ti,Zr)C-Co than WC-TiC-ZrC-Co. The shrinkage behavior and hardness of both composites are reported and discussed.

Liquid Phase Sintering of (Ti,ZrC with WC-Co

Directory of Open Access Journals (Sweden)

Taoran Ma

2017-01-01

Full Text Available (Ti,ZrC powder was sintered with WC-Co following an industrial process, including an isotherm at 1410 °C. A series of interrupted sintering trials was performed with the aim of studying the sintering behavior and the microstructural evolution during both solid-state and liquid-state sintering. Reference samples, using the same elemental compositions but with the starting components TiC and ZrC instead of (Ti,ZrC, were also sintered. The microstructure was investigated using scanning electron microscopy and energy dispersive X-ray spectroscopy. It is found that the (Ti,ZrC phase decomposes into Ti-rich and Zr-rich nano-scale lamellae before the liquid-state of the sintering initiates. The final microstructure consists of the binder and WC as well as two different γ phases, rich in either Ti (γ1 or Zr (γ2. The γ2 phase grains have a core-shell structure with a (Ti,ZrC core following the full sintering cycle. The major differences observed in (Ti,ZrC with respect to the reference samples after the full sintering cycle were the referred core-shell structure and the carbide grain sizes; additionally, the microstructural evolution during sintering differs. The grain size of carbides (WC, γ1, and γ2 is about 10% smaller in WC-(Ti,ZrC-Co than WC-TiC-ZrC-Co. The shrinkage behavior and hardness of both composites are reported and discussed.

Influence of WC addition on the microstructure and mechanical properties of NbC-Co cermets

International Nuclear Information System (INIS)

Huang, S.G.; Li, L.; Van der Biest, O.; Vleugels, J.

2007-01-01

NbC-24.5 wt.% Co cermets with up to 30 wt.% WC were obtained by solid state hot pressing at 1300 o C under a pressure of 45 MPa for 10 min and pressureless liquid phase sintering at 1360 o C for 60 min. The effect of WC addition on the microstructure and mechanical properties of NbC-Co based cermets was investigated. The hot pressed cermets exhibited interconnected and irregular niobium carbide (NbC) or (Nb,W)C grains, whereas the shape of the NbC grains changed from faceted with rounded corners to spherical, as the WC content increased in the pressureless sintered cermets. The undissolved WC increased with increasing WC addition. A clear core/rim structure was observed in the hot pressed cermets with 10-30 wt.% WC additions, whereas this structure was gradually eliminated when pressureless sintering. The hardness remains nearly constant whereas the fracture toughness slightly increases with increasing WC addition. The dissolution of WC in the Co binder and NbC grains, as well as the formation of a solid solution (Nb,W)C phase were supported by thermodynamic calculations

Fretting and wear behaviors of Ni/nano-WC composite coatings in dry and wet conditions

International Nuclear Information System (INIS)

Benea, Lidia; Başa, Sorin-Bogdan; Dănăilă, Eliza; Caron, Nadège; Raquet, Olivier; Ponthiaux, Pierre; Celis, Jean-Pierre

2015-01-01

Highlights: • The friction and wear properties of Ni/nano-WC composite were studied. • Nano-WC reinforcement decreased friction coefficient in dry and wet conditions. • Nano-WC reinforcement fraction was seen to be 12 wt.%. • Nanohardness increased by 27% compared to nickel without WC reinforcements. • Ennoblement of OCP corresponding to the Ni/nano-WC composite coating. - Abstract: The fretting and wear behaviors of Ni/nano-WC composite coatings were studied by considering the effect of fretting frequency of 1 Hz during 10,000 cycles, at different applied loads in dry or wet conditions. The studies were performed on a ball-on-disk tribometer and the results were compared with pure Ni coating. The nanohardness of pure Ni and Ni/nano-WC composite coatings was tested by nanoindentation technique. To evaluate the wet wear (tribocorrosion) behavior the open circuit potential (OCP) was measured before, during and after the fretting tests at room temperature in the solution that simulates the primary water circuit of Pressurized Water Reactors (PWRs). The results show that Ni/nano-WC composite coatings exhibited a low friction coefficient, high nanohardness and wear resistance compared with pure Ni coatings under similar experimental conditions. Ni/nano-WC composite coatings were obtained on stainless steel support by electrochemical codeposition of nano-sized WC particles (diameter size of ∼60 nm) with nickel, from a standard nickel Watts plating bath. The surface morphology and the composition of the coatings were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) respectively

Fatal hemolytic disease of the fetus and newborn associated with anti-Jr.

Science.gov (United States)

Peyrard, Thierry; Pham, Bach-Nga; Arnaud, Lionel; Fleutiaux, Sophie; Brossard, Yves; Guerin, Bénédicte; Desmoulins, Isabelle; Rouger, Philippe; Le Pennec, Pierre-Yves

2008-09-01

Jr(a) is a high-prevalence red cell (RBC) antigen. The clinical significance of anti-Jr(a) is controversial. When hemolytic disease of the fetus and newborn (HDFN) occurred, most reported cases were clinically mild. We report the first case of fatal HDFN due to anti-Jr(a). A 28-year-old Caucasian woman with transfusion history was monitored at the 29th week of pregnancy (G4P1). An ultrasound scan showed fetal cardiomegaly and hepatomegaly. An antibody directed against a high-prevalence antigen was detected, but without conclusive identification. An emergency cesarean section was performed at the 36th week. The newborn was hydropic and showed severe anemia. Death occurred 30 hours after birth. Serologic methods were performed to investigate the mother's RBCs and serum. An in vitro functional cellular assay and semiquantitative measurement of anti-Jr(a) were used to determine the clinical significance of the antibody. Anti-Jr(a) was identified in the serum and Jr(a-) phenotype was confirmed. The anti-Jr(a) titer was 1024, with predominant immunoglobulin (Ig)G1 and minor IgG4 subclasses. The functional cellular assay was consistent with an antibody unlikely to cause HDFN. Semiquantitative measurement of anti-Jr(a) showed a reactivity equivalent to a 25 IU per mL (5 microg/mL) concentration of anti-D, a value associated with a significant risk of HDFN. This is the first documented case of fatal HDFN due to anti-Jr(a). Therefore, we recommend close monitoring of pregnant women with a high-titer anti-Jr(a), especially those with an incompatible transfusion history and/or multiple pregnancies. This case report provides new arguments about the clinical significance of anti-Jr(a) in the transfusion setting.

Pd enhanced WC catalyst to promote heterogeneous methane combustion

International Nuclear Information System (INIS)

Terracciano, Anthony Carmine; De Oliveira, Samuel; Siddhanti, Deepti; Blair, Richard; Vasu, Subith S.; Orlovskaya, Nina

2017-01-01

Highlights: • Pd enhanced WC catalyst particles were synthesized via mechanochemical alloying. • Catalyst was characterized by XRD, XRF, SEM, and EDS. • Catalyst was deposited on porous ZrO_2 and evaluated in heterogeneous combustion. • During combustion temperature profiles and spectral emissions were collected. - Abstract: The efficiency of combustion for low cost heat production could be greatly enhanced if an active and low cost catalyst would be used to facilitate the chemical reactions occurring during combustor operation. Within this work an experimental study of palladium (Pd) enhanced tungsten carbide (WC) catalyst, synthesized via high energy ball milling and deposited by dip coating onto a magnesia partially stabilized zirconia (MgO-ZrO_2) porous matrix of 10 ppin was evaluated in heterogeneous methane combustion. The synthesized powder was characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) analysis, as well as by X-ray Fluorescence (XRF); and the morphology of the deposited WC-Pd coating was also characterized using SEM and EDS. Performance evaluation of the heterogeneous combustor with WC-Pd coated MgO-ZrO_2 porous media was conducted at constant air flow rate and various equivalence ratios of methane/air gaseous mixtures, while monitoring axial temperature profiles within the combustion chamber using thermocouples, as well as thermal radiative and acoustic emissions from the combustor exhaust using an externally placed CCD camera and a microphone. It was found that there is a strong dependence of flame position and maximum temperature on equivalence ratio (φ) over the range of 0.47 ± 0.02 ⩽ φ ⩽ 0.75 ± 0.02. Additionally it was found that over the same equivalence ratio range, there is a characteristic 4 peak acoustic signature between 200 and 500 Hz. It was found that at higher equivalence ratios 0.51 ± 0.02 ⩽ φ ⩽ 0.75 ± 0.02 the performance of combustor

Structure and hardness of a hard metal alloy prepared with a WC powder synthesized at low temperature

Energy Technology Data Exchange (ETDEWEB)

Costa, F.A. da [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)], E-mail: francineac@yahoo.com; Medeiros, F.F.P. de [Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Silva, A.G.P. da [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Gomes, U.U. [Departamento de Fisica Teorica e Experimental, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil); Filgueira, M. [Laboratorio de Materiais Avancados, UENF, 28015-620 Campos de Goytacazes, RJ (Brazil); Souza, C.P. de [Laboratorio de Termodinamica e Reatores, UFRN, Campus Universitario, 59072-970 Natal, RN (Brazil)

2008-06-25

The structure and hardness of a WC-10 wt% Co alloy prepared with an experimental WC powder are compared with those of another alloy of the same composition produced under the same conditions and prepared with a commercial WC powder. The experimental WC powder was synthesized by a gas-solid reaction between APT and methane at low temperature and the commercial WC powder was conventionally produced by a solid-solid reaction between tungsten and carbon black. WC-10 wt% Co alloys with the two powders were prepared under the same conditions of milling and sintering. The structure of the sample prepared with the experimental WC powder is homogeneous and coarse grained. The structure of the sample prepared with the commercial powder is heterogeneous. Furthermore the size and shape of the WC grains are significantly different.

Gene number determination and genetic polymorphism of the gamma delta T cell co-receptor WC1 genes

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Chen Chuang

2012-10-01

Full Text Available Abstract Background WC1 co-receptors belong to the scavenger receptor cysteine-rich (SRCR superfamily and are encoded by a multi-gene family. Expression of particular WC1 genes defines functional subpopulations of WC1+ γδ T cells. We have previously identified partial or complete genomic sequences for thirteen different WC1 genes through annotation of the bovine genome Btau_3.1 build. We also identified two WC1 cDNA sequences from other cattle that did not correspond to sequences in the Btau_3.1 build. Their absence in the Btau_3.1 build may have reflected gaps in the genome assembly or polymorphisms among animals. Since the response of γδ T cells to bacterial challenge is determined by WC1 gene expression, it was critical to understand whether individual cattle or breeds differ in the number of WC1 genes or display polymorphisms. Results Real-time quantitative PCR using DNA from the animal whose genome was sequenced (“Dominette” and sixteen other animals representing ten breeds of cattle, showed that the number of genes coding for WC1 co-receptors is thirteen. The complete coding sequences of those thirteen WC1 genes is presented, including the correction of an error in the WC1-2 gene due to mis-assembly in the Btau_3.1 build. All other cDNA sequences were found to agree with the previous annotation of complete or partial WC1 genes. PCR amplification and sequencing of the most variable N-terminal SRCR domain (domain 1 which has the SRCR “a” pattern of each of the thirteen WC1 genes showed that the sequences are highly conserved among individuals and breeds. Of 160 sequences of domain 1 from three breeds of cattle, no additional sequences beyond the thirteen described WC1 genes were found. Analysis of the complete WC1 cDNA sequences indicated that the thirteen WC1 genes code for three distinct WC1 molecular forms. Conclusion The bovine WC1 multi-gene family is composed of thirteen genes coding for three structural forms whose

Dr. Martin Luther King, Jr. as Spiritual Leader

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Andrea Pierce

2013-09-01

Full Text Available The purpose of this paper is to explore Dr. Martin Luther King Jr.’s spiritual leadership through his “I Have a Dream” speech. The paper explores the three characteristics of spiritual leadership as posed by Fry’s (2003 spiritual leadership theory: vision, hope/faith and altruistic love. The research draws upon these characteristics through qualitative content analysis of Dr. Martin Luther King Jr.’s “I Have a Dream” speech to illustrate Dr. King’s leadership as that of a spiritual leader. The research advances the spiritual leadership theory by establishing Dr. Martin Luther King Jr. as a spiritual leader. Through the illustration of Dr. King’s spiritual leadership, the characteristics of a spiritual leader are given tangible understanding.

WC1 is a hybrid γδ TCR coreceptor and pattern recognition receptor for pathogenic bacteria.

Science.gov (United States)

Hsu, Haoting; Chen, Chuang; Nenninger, Ariel; Holz, Lauren; Baldwin, Cynthia L; Telfer, Janice C

2015-03-01

WC1 proteins are uniquely expressed on γδ T cells and belong to the scavenger receptor cysteine-rich (SRCR) superfamily. While present in variable, and sometimes high, numbers in the genomes of mammals and birds, in cattle there are 13 distinct genes (WC1-1 to WC1-13). All bovine WC1 proteins can serve as coreceptors for the TCR in a tyrosine phosphorylation dependent manner, and some are required for the γδ T cell response to Leptospira. We hypothesized that individual WC1 receptors encode Ag specificity via coligation of bacteria with the γδ TCR. SRCR domain binding was directly correlated with γδ T cell response, as WC1-3 SRCR domains from Leptospira-responsive cells, but not WC1-4 SRCR domains from Leptospira-nonresponsive cells, bound to multiple serovars of two Leptospira species, L. borgpetersenii, and L. interrogans. Three to five of eleven WC1-3 SRCR domains, but none of the eleven WC1-4 SRCR domains, interacted with Leptospira spp. and Borrelia burgdorferi, but not with Escherichia coli or Staphylococcus aureus. Mutational analysis indicated that the active site for bacterial binding in one of the SRCR domains is composed of amino acids in three discontinuous regions. Recombinant WC1 SRCR domains with the ability to bind leptospires inhibited Leptospira growth. Our data suggest that WC1 gene arrays play a multifaceted role in the γδ T cell response to bacteria, including acting as hybrid pattern recognition receptors and TCR coreceptors, and they may function as antimicrobials. Copyright © 2015 by The American Association of Immunologists, Inc.

Small-sized and contacting Pt-WC nanostructures on graphene as highly efficient anode catalysts for direct methanol fuel cells.

Science.gov (United States)

Wang, Ruihong; Xie, Ying; Shi, Keying; Wang, Jianqiang; Tian, Chungui; Shen, Peikang; Fu, Honggang

2012-06-11

The synergistic effect between Pt and WC is beneficial for methanol electro-oxidation, and makes Pt-WC catalyst a promising anode candidate for the direct methanol fuel cell. This paper reports on the design and synthesis of small-sized and contacting Pt-WC nanostructures on graphene that bring the synergistic effect into full play. Firstly, DFT calculations show the existence of a strong covalent interaction between WC and graphene, which suggests great potential for anchoring WC on graphene with formation of small-sized, well-dispersed WC particles. The calculations also reveal that, when Pt attaches to the pre-existing WC/graphene hybrid, Pt particles preferentially grow on WC rather than graphene. Our experiments confirmed that highly disperse WC nanoparticles (ca. 5 nm) can indeed be anchored on graphene. Also, Pt particles 2-3 nm in size are well dispersed on WC/graphene hybrid and preferentially grow on WC grains, forming contacting Pt-WC nanostructures. These results are consistent with the theoretical findings. X-ray absorption fine structure spectroscopy further confirms the intimate contact between Pt and WC, and demonstrates that the presence of WC can facilitate the crystallinity of Pt particles. This new Pt-WC/graphene catalyst exhibits a high catalytic efficiency toward methanol oxidation, with a mass activity 1.98 and 4.52 times those of commercial PtRu/C and Pt/C catalysts, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement in tribological properties of atmospheric plasma-sprayed WC-Co coating followed by Cu electrochemical impregnation

International Nuclear Information System (INIS)

Yuan Jianhui; Zhu Yingchun; Zheng Xuebing; Ruan Qichao; Ji Heng

2009-01-01

The WC-Co coating obtained by atmospheric plasma spraying (APS) was modified by Cu electrochemical impregnation. The copper has infiltrated into and filled up the pores in WC-Co coating. The tribological properties of the coating against the stainless steel ball as sliding pairs were investigated with a ball-on-disc (BOD) configuration in air at room temperature. The as-prepared samples were characterized by means of optical microscope, scanning electron microscope and X-ray diffraction. It was found that the frictional behavior of the WC-Co coating followed by Cu electrochemical impregnation was superior to that of WC-Co coating. The wear mechanism of the WC-Co coating followed by Cu electrochemical impregnation was microcutting, whilst that of a WC-Co coating was the fatigue wear. The improvement in tribological properties of the WC-Co coating followed by Cu electrochemical impregnation was attributed to the formation of self-lubricating Cu film on the wear surface which induces the transformation of wear mechanism.

Draft genome sequence of Therminicola potens strain JR

Energy Technology Data Exchange (ETDEWEB)

Byrne-Bailey, K.G.; Wrighton, K.C.; Melnyk, R.A.; Agbo, P.; Hazen, T.C.; Coates, J.D.

2010-07-01

'Thermincola potens' strain JR is one of the first Gram-positive dissimilatory metal-reducing bacteria (DMRB) for which there is a complete genome sequence. Consistent with the physiology of this organism, preliminary annotation revealed an abundance of multiheme c-type cytochromes that are putatively associated with the periplasm and cell surface in a Gram-positive bacterium. Here we report the complete genome sequence of strain JR.

Pt catalysts on PANI coated WC/C nanocomposites for methanol electro-oxidation and oxygen electro-reduction in DMFC

International Nuclear Information System (INIS)

Yaldagard, Maryam; Jahanshahi, Mohsen; Seghatoleslami, Naser

2014-01-01

Highlights: • In this work nanosized WC/C were successfully coated by PANI. • Pt particles (10.56 nm) were uniformly dispersed on the surface of PANI/WC/C support. • The Pt/PANI/WC/C exhibited higher MOR activity and CO tolerance than Pt/C. • The Pt/PANI/WC/C exhibited higher activity for ORR than Pt/C in RDE experiments. • Pt/PANI/WC/C showed good stability than that of Pt/C in the presence of methanol. - Abstract: In the present study a Pt/PANI/WC/C electrocatalyst was developed to increase the methanol electro-oxidation and oxygen electro-reduction activity and stability of commercial Pt/C electrocatalyst. WC/C was coated with protonated polyaniline (PANI) in situ during the polymerization of aniline. Fourier transform infrared (FTIR) results illustrate the presence of PANI in the composite. The conductivity of PANI coated – WC/C has been compared with the conductivity of the corresponding mixtures of WC/C and Vulcan XC-72. X-ray diffraction results showed that Pt particles were dispersed on the support with mean particle size of about 10.56 nm. Transition electron microscopy images showed that the nanosized WC/C were successfully coated by PANI. Based on the electrochemical properties characterized by cyclic voltammetry, CO stripping and rotating disk electrode measurements it was found that the as prepared Pt/PANI/WC/C electrocatalyst exhibited a comparable activity for methanol oxidation reaction and oxygen reduction reaction with respect to the commercial one. A significant reduction in the potential of CO electro-oxidation peak from 0.75 V for Pt/C to 0.52 V for Pt/PANI/WC/C electrocatalyst indicates that an increase in the activity for CO electro-oxidation is achieved by replacing the carbon support by PANI coated WC/C. Chronoamerometry results also showed, in the presence of methanol the Pt/PANI/WC/C electrocatalyst still maintains a higher current density than Pt/WC/C and Pt/C

Pt catalysts on PANI coated WC/C nanocomposites for methanol electro-oxidation and oxygen electro-reduction in DMFC

Energy Technology Data Exchange (ETDEWEB)

Yaldagard, Maryam, E-mail: m_yaldagard@yahoo.com [Department of Chemical Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111 (Iran, Islamic Republic of); Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology (Iran, Islamic Republic of); Jahanshahi, Mohsen, E-mail: mjahan@nit.um.ac.ir [Nanotechnology Research Institute, School of Chemical Engineering, Babol University of Technology (Iran, Islamic Republic of); Seghatoleslami, Naser, E-mail: Slami@um.ac.ir [Department of Chemical Engineering, Ferdowsi University of Mashhad, P.O. Box 91775-1111 (Iran, Islamic Republic of)

2014-10-30

Highlights: • In this work nanosized WC/C were successfully coated by PANI. • Pt particles (10.56 nm) were uniformly dispersed on the surface of PANI/WC/C support. • The Pt/PANI/WC/C exhibited higher MOR activity and CO tolerance than Pt/C. • The Pt/PANI/WC/C exhibited higher activity for ORR than Pt/C in RDE experiments. • Pt/PANI/WC/C showed good stability than that of Pt/C in the presence of methanol. - Abstract: In the present study a Pt/PANI/WC/C electrocatalyst was developed to increase the methanol electro-oxidation and oxygen electro-reduction activity and stability of commercial Pt/C electrocatalyst. WC/C was coated with protonated polyaniline (PANI) in situ during the polymerization of aniline. Fourier transform infrared (FTIR) results illustrate the presence of PANI in the composite. The conductivity of PANI coated – WC/C has been compared with the conductivity of the corresponding mixtures of WC/C and Vulcan XC-72. X-ray diffraction results showed that Pt particles were dispersed on the support with mean particle size of about 10.56 nm. Transition electron microscopy images showed that the nanosized WC/C were successfully coated by PANI. Based on the electrochemical properties characterized by cyclic voltammetry, CO stripping and rotating disk electrode measurements it was found that the as prepared Pt/PANI/WC/C electrocatalyst exhibited a comparable activity for methanol oxidation reaction and oxygen reduction reaction with respect to the commercial one. A significant reduction in the potential of CO electro-oxidation peak from 0.75 V for Pt/C to 0.52 V for Pt/PANI/WC/C electrocatalyst indicates that an increase in the activity for CO electro-oxidation is achieved by replacing the carbon support by PANI coated WC/C. Chronoamerometry results also showed, in the presence of methanol the Pt/PANI/WC/C electrocatalyst still maintains a higher current density than Pt/WC/C and Pt/C.

Erosion resistance of FeAl-TiB2 and FeAl-WC at room and elevated temperatures

International Nuclear Information System (INIS)

Alman, D.E.; Tylczak, J.H.; Hawk, J.A.

2000-01-01

The resistance of FeAl-40%TiB 2 and FeAl-80%WC cermets to solid particle erosion at 25, 180, 500 and 700 C was evaluated and compared to the behavior of WC-6%Co (Co-90%WC) cemented carbides. Even though the WC-Co contained a higher volume fraction of the hard phase, the erosion rates of the FeAl-cermets were similar in magnitude to the erosion rates of the WC-Co. However, the erosion rates of the FeAl-cermets either were constant (FeAl-TiB 2 ) or decreased (FeAl-WC) with increasing test temperature; whereas, the erosion rates of the WC-Co cemented carbides increased with increasing test temperature. This indicated that once the microstructures of the FeAl-cermets are optimized for wear resistance, these materials might make promising candidates for high-temperature wear applications

High Temperature Dry Sliding Friction and Wear Performance of Laser Cladding WC/Ni Composite Coating

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YANG Jiao-xi

2016-06-01

Full Text Available Two different types of agglomerate and angular WC/Ni matrix composite coatings were deposited by laser cladding. The high temperature wear resistance of these composite coatings was tested with a ring-on-disc MMG-10 apparatus. The morphologies of the worn surfaces were observed using a scanning electron microscopy (SEM equipped with an energy dispersive spectroscopy (EDS for elemental composition. The results show that the high temperature wear resistance of the laser clad WC/Ni-based composite coatings is improved significantly with WC mass fraction increasing. The 60% agglomerate WC/Ni composite coating has optimal high temperature wear resistance. High temperature wear mechanism of 60% WC/Ni composite coating is from abrasive wear of low temperature into composite function of the oxidation wear and abrasive wear.

TRIBOLOGICAL PROPERTIES OF TiBx AND WC/C COATINGS

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PETER KÚŠ

2011-12-01

Full Text Available Tribological properties of TiBx and WC/C coatings have been studied using the ball-on-disc method at room and elevated temperatures in air to investigate their behavior under conditions approaching high performance dry cutting. The average room temperature coefficients of friction (COF of both nanocomposite DC magnetron sputtered TiBx coatings and PECVD WC/C coatings were in the range 0.2-0.6. The lowest value of TiBx coatings of 0.16 was achieved in case of prefferentially oriented stuctures deposited at the highest negative bias. The lowest COF of WC/C was around 0.11. The increase of testing temperature to 450°C caused the increase of COF up to approximately 0.7-0.8. The experiments at elevated temperatures suggest the existence of the oxide transfer film with higher COF than that of the sliding contact without the film. Although both coating systems have relatively high COF values at elevated temperatures, they exhibit elements of some adaptive behavior.

Microstructure and property of WC particles ceramic-metal composite coatings by laser surface cladding

International Nuclear Information System (INIS)

Zeng Xiaoyan; Zhu Beidi; Tao Zengyi; Yang Shuguo; Cui Kun

1993-01-01

Ceramic-metal is widely used as a kind of good hardfacing material. The coarse WC particles ceramic-metal composite coatings with WC density of 67% it weight and the thickness of 1.6-2.0 mm have been cladded on 20Ni 4 Mo steel surface by a 2kw CO 2 laser. The sintered WC particles with the size of 600-1,000 μm are chosen as the main strengthening phase, Ni-base self-flux alloy as the binder in the composite coatings. The microstructure and micro-hardness of both WC particles and binder are analyzed. The rigid ball indention with acoustic emission technique is used to evaluate the brittleness of the coating. Finally, the abrasive wear resistance of the coatings are tested, Besides, the coatings with the same ratio and size of WC particles within low carbon steel tube were cladded on 20Ni 4 Mo steel by atomic hydrogen welding technique and analyzed by the same ways their result are compared

Microstructural examination by TEM of WC/Co composites prepared by conventional and Microwave processes

International Nuclear Information System (INIS)

Agrawal, D.; Cheng, J.; Papworth, A.J.; Jain, H.; Williams, D.B.

2001-01-01

Recently, significant developments and advances have taken place in the field of microwave processing of ceramics, composites and metals. Microwave sintering technology of WC/Co based hard metal parts has been now developed for commercial products. Microwave processed WC/Co parts reportedly have exhibited superior performance over standard parts. Additionally, the microwave process requires only one tenth of the total cycle time employed in a conventional process. Laboratory corrosion and impact resistance tests have proved that microwave processed WC/Co parts are several times more resistant than the conventional parts of the same composition. The scanning transmission electron microscopic (STEM) examination conducted an conventionally and microwave sintered WC/Co samples exhibited remarkable difference in the chemistry of cobalt binder phase. It is understood that the superior mechanical properties of microwave sintered part are due to the pure cobalt phase present at the grain boundary of WC grains, while the conventionally sintered part showed there was substantial inter-alloying of Co with tungsten. (author)

Physical properties and microstructure of Ti(CN)-based cermets with different WC particle size

International Nuclear Information System (INIS)

Deng, Ying; Deng, Ling; Xiong, Xiang; Ye, J.W.; Li, P.P.

2014-01-01

Ti(CN)-based cermets with different WC particle sizes from 0.2 to 4 μm were prepared at 1450 °C with 2 MPa Air pressure. The microstructure of cermets was investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), Transmission electron microscope (TEM). The results showed that all the cermets with different WC particle sizes have a typical “core–rim” structure. With the increase of WC powder sizes, the frequency and portion of Ti(C 0.7 N 0.3 ) cores and rim are somewhat decreased while the portion of white core is increased, due to the relative dissolution rate decreasing. In addition, the fracture mode of Ti(C,N) based cermets is a mixture of trans-granular (primary) and inter-granular (subordinate) fracture. The TRS (about 1850 MPa) of the cermets fluctuate slightly with the WC particle sizes from 0.2 to 1.0 μm, but decrease evidently with WC particle sizes up to 2 μm

Framework for technical assessment in JR Maglev

Energy Technology Data Exchange (ETDEWEB)

Seki, Akio [Central Japan Railway Co., Tokyo (Japan); Akahoshi, Toru [Central Japan Railway Co., Tokyo (Japan); Furuki, Tsutomu [Railway Technical Research Inst., Tokyo (Japan)

1995-12-31

In the course of development of JR Maglev, various technical assessments are carried out at each stage of development by a system management group of a project team in order to achieve goals of development. For the purpose, guidelines for practicality assessment were prepared at design stage. It is now striven to make test plans necessary for the practicality assessment. This assessment will serve for those to be ultimately implemented by Ministry of Transport (MOT). This paper presents an overview of concepts, methods and procedures of the technical assessments especially focused on the practicality assessment in the development of JR Maglev. (orig.)

Microstructure and mechanical properties of TiB2–TiC–WC composite ceramic tool materials

International Nuclear Information System (INIS)

Song, Jinpeng; Huang, Chuanzhen; Zou, Bin; Liu, Hanlian; Wang, Jun

2012-01-01

Highlights: ►Effect of sintering parameters on TiB 2 –TiC–WC composites has been investigated. ► Ni element was dispersed in the interface between WC and matrix grains. ► The fracture mode changed from intergranular fracture to transgranular fracture. ► The microstructure and mechanical properties of the composite were improved. -- Abstract: TiB 2 –TiC–WC composites with Ni as a sintering aid were fabricated by a hot-press technique at 1700 °C and 1650 °C for 1 h, respectively. The microstructure and mechanical properties were investigated. The composites were analyzed by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS). The matrix phases consisted of TiB 2 and TiC. No severe chemical reactions happened between the additive and matrix. The microstructure consisted of the fine WC grains and uniform matrix grains. When the proper WC content added to TiB 2 –TiC composites, the growth of matrix grains was inhibited and the mechanical properties of the composites were improved. The interface energy was strengthened by Ni that dispersed in the interfaces among WC grains and matrix grains, which made the fracture mode change from intergranular fracture to transgranular fracture. The transgranular fracture and the pulling out of WC grains played a predominant role in the propagating of cracks when WC content was 20 wt.% in TiB 2 –TiC–WC composites. The optimal mechanical properties of TiB 2 –TiC–20 wt.%WC composite were 955.71 MPa of flexural strength, 7.5 MPa m 1/2 of fracture toughness and 23.5 GPa of Vickers hardness.

PREPARATION OF WC-Co POWDER BY DIRECT REDUCTION AND CARBONIZATION

Institute of Scientific and Technical Information of China (English)

Zhonglai Yi; Gangqin Shao; Xinglong Duan; Peng Sun; Xiaoliang Shi; Zhen Xiong; Jingkun Guo

2005-01-01

A new approach to produce superfine WC-Co powder by direct reduction and carbonization is proposed.Water-soluble salts containing W and Co were used as raw materials. Tungsten and cobalt oxide powder (CoWO4/WO3)was first formed by a spray-pyrolysis technique, which was then mixed with carbon black and converted to WC-Co composite powder at 950℃ for 4 h in N2 atmosphere. The resulting powder has a particle size of 100-300 nm.

Surface analysis of WC--Co composite materials (2) Quantitative Auger electron spectrometry

International Nuclear Information System (INIS)

Tongson, L.L.; Biggers, J.V.; Dayton, G.O.; Bind, J.M.; Knox, B.E.

1978-01-01

The unique sensitivity of Auger electron spectrometry (AES) to combined carbon has been exploited in measuring the surface compositions of hot-pressed, conventionally sintered and mixed powders of WC--Co composite materials. AES sensitivity factors for tungsten and carbon (in WC) relative to cobalt were determined. The concentrations of the major elements in hot-pressed samples measured with AES using the relative sensitivity method were compared to those obtained independently by electron microprobe (EMP) and x-ray fluorescence (XRF) techniques. Corollary studies using ion scattering spectrometry (ISS) showed the absence of (1) matrix effects in the AES measurements, (2) preferential sputtering during ion bombardment, and (3) deposition of the easier-to-sputter component (cobalt) onto WC

Exploring the potential role of tungsten carbide cobalt (WC-Co) nanoparticle internalization in observed toxicity toward lung epithelial cells in vitro

Energy Technology Data Exchange (ETDEWEB)

Armstead, Andrea L. [Biomaterials, Bioengineering and Nanotechnology Laboratory, Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV 26506 (United States); Pharmaceutical and Pharmacological Sciences Graduate Program, School of Pharmacy, West Virginia University, Morgantown, WV 26506 (United States); Arena, Christopher B. [Biomaterials, Bioengineering and Nanotechnology Laboratory, Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV 26506 (United States); E.J. Van Liere Research Program, School of Medicine, West Virginia University, Morgantown, WV 26506 (United States); Li, Bingyun, E-mail: bili@hsc.wvu.edu [Biomaterials, Bioengineering and Nanotechnology Laboratory, Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown, WV 26506 (United States); Pharmaceutical and Pharmacological Sciences Graduate Program, School of Pharmacy, West Virginia University, Morgantown, WV 26506 (United States); E.J. Van Liere Research Program, School of Medicine, West Virginia University, Morgantown, WV 26506 (United States); Mary Babb Randolph Cancer Center, Morgantown, WV 26506 (United States)

2014-07-01

Tungsten carbide cobalt (WC-Co) has been recognized as a workplace inhalation hazard in the manufacturing, mining and drilling industries by the National Institute of Occupational Safety and Health. Exposure to WC-Co is known to cause “hard metal lung disease” but the relationship between exposure, toxicity and development of disease remain poorly understood. To better understand this relationship, the present study examined the role of WC-Co particle size and internalization on toxicity using lung epithelial cells. We demonstrated that nano- and micro-WC-Co particles exerted toxicity in a dose- and time-dependent manner and that nano-WC-Co particles caused significantly greater toxicity at lower concentrations and shorter exposure times compared to micro-WC-Co particles. WC-Co particles in the nano-size range (not micron-sized) were internalized by lung epithelial cells, which suggested that internalization may play a key role in the enhanced toxicity of nano-WC-Co particles over micro-WC-Co particles. Further exploration of the internalization process indicated that there may be multiple mechanisms involved in WC-Co internalization such as actin and microtubule based cytoskeletal rearrangements. These findings support our hypothesis that WC-Co particle internalization contributes to cellular toxicity and suggest that therapeutic treatments inhibiting particle internalization may serve as prophylactic approaches for those at risk of WC-Co particle exposure. - Highlights: • Hard metal (WC-Co) particle toxicity was established in lung epithelial cells. • Nano-WC-Co particles caused greater toxicity than micro-WC-Co particles. • Nano- and micro-WC-Co particles were capable of inducing cellular apoptosis. • Nano-WC-Co particles were internalized by lung epithelial cells. • WC-Co particle internalization was mediated by actin dynamics.

Exploring the potential role of tungsten carbide cobalt (WC-Co) nanoparticle internalization in observed toxicity toward lung epithelial cells in vitro

International Nuclear Information System (INIS)

Armstead, Andrea L.; Arena, Christopher B.; Li, Bingyun

2014-01-01

Tungsten carbide cobalt (WC-Co) has been recognized as a workplace inhalation hazard in the manufacturing, mining and drilling industries by the National Institute of Occupational Safety and Health. Exposure to WC-Co is known to cause “hard metal lung disease” but the relationship between exposure, toxicity and development of disease remain poorly understood. To better understand this relationship, the present study examined the role of WC-Co particle size and internalization on toxicity using lung epithelial cells. We demonstrated that nano- and micro-WC-Co particles exerted toxicity in a dose- and time-dependent manner and that nano-WC-Co particles caused significantly greater toxicity at lower concentrations and shorter exposure times compared to micro-WC-Co particles. WC-Co particles in the nano-size range (not micron-sized) were internalized by lung epithelial cells, which suggested that internalization may play a key role in the enhanced toxicity of nano-WC-Co particles over micro-WC-Co particles. Further exploration of the internalization process indicated that there may be multiple mechanisms involved in WC-Co internalization such as actin and microtubule based cytoskeletal rearrangements. These findings support our hypothesis that WC-Co particle internalization contributes to cellular toxicity and suggest that therapeutic treatments inhibiting particle internalization may serve as prophylactic approaches for those at risk of WC-Co particle exposure. - Highlights: • Hard metal (WC-Co) particle toxicity was established in lung epithelial cells. • Nano-WC-Co particles caused greater toxicity than micro-WC-Co particles. • Nano- and micro-WC-Co particles were capable of inducing cellular apoptosis. • Nano-WC-Co particles were internalized by lung epithelial cells. • WC-Co particle internalization was mediated by actin dynamics

Benzotriazole (BTA), A Promising Corrosion Inhibitor for WC-Co Hardmetal

Energy Technology Data Exchange (ETDEWEB)

Schnyder, B.; Stoessel-Sittig, C.; Koetz, R.; Hochstrasser-Kurz, S. [ETH Zuerich (Switzerland); Virtanen, S. [ETH Zuerich (Switzerland); Jaeggi, Ch. [University of Bern (Switzerland); Eichenberger, N. [University of Bern (Switzerland); Szoecs, E. [University of Bern (Switzerland); Siegenthaler, H. [University of Bern (Switzerland); Ziegler, P. [AGIE SA (Switzerland); Beltrami, I. [AGIE SA (Switzerland)

2004-03-01

Wire Electro-Discharge Machining (W-EDM) of tungsten carbide with Co-binder may lead to corrosion and discolouration at the surface. The corrosion behaviour of WC-Co based hardmetal was investigated in different aqueous solutions (acidic, neutral, and alkaline solutions). At open-circuit potential WC-Co based hardmetals show rather high dissolution rates in all types of electrolyte. An efficient corrosion inhibitor (benzotriazole, C{sub 6}H{sub 5}N{sub 3}) could be found for a borate buffer solution, pH = 8.4. (author)

Production and Characterization of WC-Reinforced Co-Based Superalloy Matrix Composites

Science.gov (United States)

Özgün, Özgür; Dinler, İlyas

2018-05-01

Cobalt-based superalloy matrix composite materials were produced through the powder metallurgy technique using element powders at high purity and nano-sized wolfram carbide (WC) reinforcement in this study. An alloy that had the same chemical composition as the Stellite 6 alloy but not containing carbon was selected as the matrix alloy. The powder mixtures obtained as a result of mixing WC reinforcing member and element powders at the determined ratio were shaped by applying 300 MPa of pressure. The green components were sintered under argon atmosphere at 1240 °C for 120 minutes. The densities of the sintered components were determined by the Archimedes' principle. Microstructural characterization was performed via X-ray diffraction analysis, scanning electron microscope examinations, and energy-dispersive spectrometry. Hardness measurements and tensile tests were performed for determining mechanical characteristics. The relative density values of the sintered components increased by increasing the WC reinforcement ratio and they could almost reach the theoretical density. It was determined from the microstructural examinations that the composite materials consisted of fine and equiaxed grains and coarse carbides demonstrating a homogeneous dispersion along the microstructure at the grain boundaries. As it was the case in the density values, the hardness and strength values of the composites increased by increasing the WC ratio.

Fracture toughness measurements of WC-based hard metals

International Nuclear Information System (INIS)

Prakash, L.; Albert, B.

1983-01-01

The fracture toughness of WC-based cemented carbides was determined by different methods. The values obtained are dependent on the procedure of measurement. Each method thoughness of hard metals mutually. (orig.) [de

78 FR 5247 - Martin Luther King, Jr., Federal Holiday, 2013

Science.gov (United States)

2013-01-24

..., 2013 Martin Luther King, Jr., Federal Holiday, 2013 By the President of the United States of America A... thousands upon thousands rallying for jobs and freedom, the Reverend Dr. Martin Luther King, Jr., delivered... Constitution and the laws of the United States, do hereby proclaim January 21, 2013, as the Martin Luther King...

The Newest Monument: The Martin Luther King, Jr. National Memorial

Science.gov (United States)

Social Studies and the Young Learner, 2011

2011-01-01

This article features the newest monument, the Martin Luther King, Jr. National Memorial. The memorial on the National Mall in Washington, D.C., honoring Dr. Martin Luther King, Jr. will be an engaging landscape experience to convey four fundamental and recurring themes throughout Dr. King's life--democracy, justice, hope, and love. Natural…

Soft phonon modes driven huge difference on lattice thermal conductivity between topological semimetal WC and WN

Science.gov (United States)

Guo, San-Dong; Chen, Peng

2018-04-01

Topological semimetals are currently attracting increasing interest due to their potential applications in topological qubits and low-power electronics, which are closely related to their thermal transport properties. Recently, the triply degenerate nodal points near the Fermi level of WC are observed by using angle-resolved photoemission spectroscopy. In this work, by solving the Boltzmann transport equation based on first-principles calculations, we systematically investigate the phonon transport properties of topological semimetals WC and WN. The predicted room-temperature lattice thermal conductivities of WC (WN) along the a and c directions are 1140.64 (7.47) W m-1 K-1 and 1214.69 (5.39) W m-1 K-1. Considering the similar crystal structure of WC and WN, it is quite interesting to find that the thermal conductivity of WC is more than two orders of magnitude higher than that of WN. It is found that, different from WN, the large acoustic-optical (a-o) gap prohibits the acoustic+acoustic → optical (aao) scattering, which gives rise to very long phonon lifetimes, leading to ultrahigh lattice thermal conductivity in WC. For WN, the lack of an a-o gap is due to soft phonon modes in optical branches, which can provide more scattering channels for aao scattering, producing very short phonon lifetimes. Further deep insight can be attained from their different electronic structures. Distinctly different from that in WC, the density of states of WN at the Fermi level becomes very sharp, which leads to destabilization of WN, producing soft phonon modes. It is found that the small shear modulus G and C44 limit the stability of WN, compared with WC. Our studies provide valuable information for phonon transports in WC and WN, and motivate further experimental studies to study their lattice thermal conductivities.

The influence of aggregates type on W/C ratio on the strength and other properties of concrete

Science.gov (United States)

Malaiskiene, J.; Skripkiunas, G.; Vaiciene, M.; Karpova, E.

2017-10-01

The influence of different types of aggregates and W/C ratio on concrete properties is analysed. In order to achieve this aim, lightweight (with expanded clay aggregate) and normal concrete (with gravel aggregate) mixtures are prepared with different W/C ratios. Different W/C ratios are selected by reducing the amount of cement when the amount of water is constant. The following properties of concrete have been determined: density, compressive strength and water absorption. Additionally, the statistical data analysis is performed and influence of aggregate type and W/C ratio on concrete properties is determined. The empirical equations indicating dependence between concrete strength and W/C and strength of aggregate are obtained for normal concrete and light-weight concrete.

Nanotoxicity: emerging concerns regarding nanomaterial safety and occupational hard metal (WC-Co) nanoparticle exposure.

Science.gov (United States)

Armstead, Andrea L; Li, Bingyun

As the number of commercial and consumer products containing engineered nanomaterials (ENMs) continually rises, the increased use and production of these ENMs presents an important toxicological concern. Although ENMs offer a number of advantages over traditional materials, their extremely small size and associated characteristics may also greatly enhance their toxic potentials. ENM exposure can occur in various consumer and industrial settings through inhalation, ingestion, or dermal routes. Although the importance of accurate ENM characterization, effective dosage metrics, and selection of appropriate cell or animal-based models are universally agreed upon as important factors in ENM research, at present, there is no "standardized" approach used to assess ENM toxicity in the research community. Of particular interest is occupational exposure to tungsten carbide cobalt (WC-Co) "dusts," composed of nano- and micro-sized particles, in hard metal manufacturing facilities and mining and drilling industries. Inhalation of WC-Co dust is known to cause "hard metal lung disease" and an increased risk of lung cancer; however, the mechanisms underlying WC-Co toxicity, the inflammatory disease state and progression to cancer are poorly understood. Herein, a discussion of ENM toxicity is followed by a review of the known literature regarding the effects of WC-Co particle exposure. The risk of WC-Co exposure in occupational settings and the updates of in vitro and in vivo studies of both micro- and nano-WC-Co particles are discussed.

A theoretical understanding on the CO-tolerance mechanism of the WC(0001) supported Pt monolayer: Some improvement strategies

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xilin [College of Physics and Materials Science, Henan Normal University, Xinxiang, 453007 (China); Lu, Zhansheng [College of Physics and Materials Science, Henan Normal University, Xinxiang, 453007 (China); Collaborative Innovation Center of Nano Functional Materials and Applications, Henan Province (China); Yang, Zongxian, E-mail: yzx@henannu.edu.cn [College of Physics and Materials Science, Henan Normal University, Xinxiang, 453007 (China); Collaborative Innovation Center of Nano Functional Materials and Applications, Henan Province (China)

2016-12-15

Highlights: • The mechanism of CO tolerance and oxidation on Pt{sub ML}/WC(0001) is clarified. • The high tolerance of Pt{sub ML}/WC(0001) to CO originate from the weak adsorption. • The minimum energy path and the rate-determining step are identified. • The activity of Pt{sub ML}/WC(0001) to CO oxidation is comparable to that of Pt(111). • Some probable strategies are proposed to improve the activity of Pt{sub ML}/WC(0001). - Abstract: The deposition of platinum on the tungsten carbide (Pt/WC) have been achieved and proved with high stability, activity and CO-tolerance toward some reactions in experiments. Although a lot of experimental efforts have been focused on understanding the activity, stability and CO-tolerance of Pt/WC, the relevant theoretical works related to the CO-tolerance mechanism are still scarce. In current study, the adsorption and oxidation of CO on the Pt monolayer supported on WC(0001) surface (Pt{sub ML}/WC(0001)) are investigated using density functional theory calculations. It is found that the oxidation of CO on Pt{sub ML}/WC(0001) proceeds preferably along the Langmuir-Hinshelwood mechanism. The energy barrier of 1.06 eV for the rate-determining step of OOCO formation is almost equal to that (1.05 eV) for CO oxidation by atomic O on Pt(111), while the adsorption energy of 1.59 eV for CO on Pt{sub ML}/WC(0001) is smaller than that on Pt(111) (1.85 eV), indicating that the high resistance to CO poisoning of Pt{sub ML}/WC(0001) may originate from the weak interaction between them. To further improve the CO tolerance, some probable strategies are proposed based on the relevant kinetics results. The current results are helpful to understanding the origin of the highly resistant to CO poisoning of Pt{sub ML}/WC(0001) and rationally designing catalysts to improve the CO oxidation activity.

Case report: massive postpartum transfusion of Jr(a+) red cells in the presence of anti-Jra.

Science.gov (United States)

Yuan, S; Armour, R; Reid, A; Abdel-Rahman, K F; Rumsey, D M; Phillips, M; Nester, T

2005-01-01

Jr(a) is a high-prevalence antigen. The rare Jr(a-) individuals can form anti-Jr(a) after exposure to the Jr(a) antigen through transfusion or pregnancy. The clinical significance of anti-Jr(a) is not well established. This study reports a case of a 31-year-old woman with a previously identified anti-Jr(a) who required massive transfusion of RBCs after developing life-threatening postpartum disseminated intravascular coagulopathy. Despite the emergent transfusion of 15 units of Jr(a) untested RBCs, she did not develop laboratory or clinical evidence of acute hemolysis. The patient's anti-Jr(a) had a pretransfusion titer of 4 and a monocyte monolayer assay (MMA) reactivity of 68.5% (reactivity > 5% is considered capable of shortening the survival of incompatible RBCs). The titer increased fourfold to 64 and the MMA reactivity was 72.5% on Day 10 posttransfusion. Review of laboratory data showed evidence of a mild delayed hemolytic transfusion reaction by Day 10 posttransfusion. Despite rare reports of hemolytic transfusion reactions due to anti-Jr(a) in the literature, most cases, including this one, report that this antibody is clinically insignificant or causes only mild delayed hemolysis. Clinicians should be advised to balance the risks of withholding transfusion with the small chance of significant hemolysis after transfusion of Jr(a+) RBCs in the presence of anti-Jr(a).

Mechanical properties of hot-pressed Al-4.5 wt. % Cu/WC composite

Directory of Open Access Journals (Sweden)

Samaneh Bernoosi

2014-12-01

Full Text Available In this study, the elemental powders of aluminum and copper were initially subjected to mechanical alloying using an attrition ball mill under argon atmosphere to produce an Al-4.5 wt% Cu powder alloy. The WC nanoparticles were then added to the powder alloy and milled in a planetary ball mill to explore the role of the WC nanoparticles on the mechanical properties of the fabricated composite powder. The experimental results revealed that a solid solution of Al-Cu could be formed after MA and a good dispersion of the WC nanoparticles in the aluminum matrix was obtained as characterized using X-ray diffraction and scanning electron microscopy, respectively. The results of hardness and compression tests of the hot pressed composites indicated that the MA followed by the hot-press processes was successful to fabricate an alloy and a metal matrix composite with considerable mechanical properties. However, a decreasing trend in the hardness and strength of the composites with the WC contents of more than 5wt% was observed. The maximum values of 260 HV and 575 MPa were obtained for a composite containing 5 wt% of nano ceramic particles.

Compression deformation of WC: atomistic description of hard ceramic material

Science.gov (United States)

Feng, Qing; Song, Xiaoyan; Liu, Xuemei; Liang, Shuhua; Wang, Haibin; Nie, Zuoren

2017-11-01

The deformation characteristics of WC, as a typical hard ceramic material, were studied on the nanoscale using atomistic simulations for both the single-crystal and polycrystalline forms under uniaxial compression. In particular, the effects of crystallographic orientation, grain boundary coordination and grain size on the origin of deformation were investigated. The deformation behavior of the single-crystal and polycrystalline WC both depend strongly on the orientation towards the loading direction. The grain boundaries play a significant role in the deformation coordination and the potential high fracture toughness of the nanocrystalline WC. In contrast to conventional knowledge of ceramics, maximum strength was obtained at a critical grain size corresponding to the turning point from a Hall-Petch to an inverse Hall-Petch relationship. For this the mechanism of the combined effect of dislocation motion within grains and the coordination of stress concentration at the grain boundaries were proposed. The present work has moved forward our understanding of plastic deformability and the possibility of achieving a high strength of nanocrystalline ceramic materials.

The Words of Martin Luther King, Jr.

Science.gov (United States)

Today's Education, 1979

1979-01-01

Excerpts from speeches by Dr. Martin Luther King, Jr., are reprinted. Topics discussed include discrimination, the South, education, nonviolent resistance, poverty, economic opportunity, and world peace. (LH)

Binder extrusion of sliding wear of WC-Co alloys

International Nuclear Information System (INIS)

Larsen-Basse, J.

1985-01-01

It has previously been proposed that preferential removal of the cobalt binder is an important mechanism in the abrasive wear of cemented carbides in the WC-Co family. It is here demonstrated that binder extrusion occurs also in metal-to-metal sliding wear contacts. The wear scar generated by sliding a hardened steel ball repeatedly over a polished WC-Co surface was studied by SEM. The extruded cobalt fragments accumulate by surface defects, such as cracks caused by the sliding loaded ball, and gradual microfragmentation of the carbide grains follows. The energy required to extrude the cobalt and cause the gradual change in surface layer microstructure is provided by the frictional forces

Elastic-plastic fracture assessment using a J-R curve by direct method

International Nuclear Information System (INIS)

Asta, E.P.

1996-01-01

In the elastic-plastic evaluation methods, based on J integral and tearing modulus procedures, an essential input is the material fracture resistance (J-R) curve. In order to simplify J-R determination direct, a method from load-load point displacement records of the single specimen tests may be employed. This procedure has advantages such as avoiding accuracy problems of the crack growth measuring devices and reducing testing time. This paper presents a structural integrity assessment approach, for ductile fracture, using the J-R obtained by a direct method from small single specimen fracture tests. The J-R direct method was carried out by means of a developed computational program based on theoretical elastic-plastic expressions. A comparative evaluation between the direct method J resistance curves and those obtained by the standard testing methodology on typical pressure vessel steels has been made. The J-R curves estimated from the direct method give an acceptable agreement with the approach proposed in this study which is reliable to use for engineering determinations. (orig.)

Machinability and scratch wear resistance of carbon-coated WC inserts

Energy Technology Data Exchange (ETDEWEB)

Pazhanivel, B., E-mail: palcecri@yahoo.co.in; Kumar, T. Prem; Sozhan, G.

2015-03-15

Highlights: • Cemented WC inserts were coated with carbon by CVD. • The deposits were either loosely held MWCNTs or adherent carbides. • Co-efficient of friction (ramp load; 1–13 N); 0.2 and 0.1 μ, respectively, for the uncoated and carbide-coated inserts. • The carbide-coated insert exhibited better machinability and surface finish than a commercial TiCN-coated insert. - Abstract: In this work, cemented tungsten carbide (WC) inserts were coated with nanocarbons/carbides by chemical vapor deposition (CVD) and their machinability and scratch wear resistance were investigated. The hardness and surface conditions of the WC substrate were studied before and after coating. The CVD-generated nanocarbons on the insert surfaces were examined by SEM, FE-SEM and TEM. The electron microscopic images revealed that the carbons generated were multi-walled carbon nanotubes (MWCNTs) or carbides depending on the experimental conditions. In both the cases, the cutting edges of the inserts had dense deposits. Scratch wear test with the coated inserts showed that the co-efficient of friction was 0.1 μ as against 0.2 μ for the uncoated inserts under a ramp load of 1–13 N. The machinability characteristics of commercially available TiCN-coated inserts and the carbon-coated WC inserts were compared by using a CNC machine and a Rapid I vision inspection system. It was found that the carbide-coated inserts exhibited machinability with better surface finish comparable to that of the TiCN-coated inserts while the MWCNT-coated inserts showed inferior adhesion properties.

Metallography and quality of dies made from WC-Co cemented carbides; Metallographie und Qualitaetskontrolle von WC-Co-Hartmetallmatrizen

Energy Technology Data Exchange (ETDEWEB)

Forejt, M. [Inst. of Technology, Faculty of Mechanical Engineering, Technical Univ., Brno (Czech Republic); Krejcova, J. [Inst. of Technology, Faculty of Mechanical Engineering, Technical Univ., Brno (Czech Republic); Smutna, J. [Inst. of Physics of Materials, ASCR, Brno (Czech Republic); Krejci, J. [Inst. of Physics of Materials, ASCR, Brno (Czech Republic)

1995-05-01

As opposite to cutting tools made from cemented carbides, forming tools (dies) seem to be on the periphery of the interest, although specific loading conditions (increased temperature, relatively high strain rate, high pressure and cyclic loading) impose different requirements on the material. The present paper contains results of light and SEM metallography of WC + Co cemented carbide dies used for screw nuts production. Two problems were pursued viz. final preparation of the surface of operative cavity after drilling and defects that appear when recycled cemented carbides are used for die production. (orig.) [Deutsch] Im Gegensatz zu Hartmetall-Schneidwerkzeugen scheinen Formwerkzeuge (Matrizen) nur am Rande des Interesses zu liegen, obwohl hier die spezifischen Beanspruchungsbedingungen (hoehere Temperaturen, relativ hohe Dehnrate, hoher Druck und zyklische Belastung) zu besonderen Anforderungen an den Werkstoff fuehren. Es werden die Ergebnisse der lichtmikroskopischen und REM-Untersuchungen an WC-Co-Hartmetallmatrizen fuer die Mutternherstellung beschrieben. Zwei Themen werden behandelt, und zwar die Endbearbeitung der Formhohlraum-Oberflaeche nach dem Bohren und die Fehler, die durch die Verwendung von Hartmetallschrott fuer die Matrizenherstellung auftreten koennen. (orig.)

Exploring the potential role of tungsten carbide cobalt (WC-Co) nanoparticle internalization in observed toxicity toward lung epithelial cells in vitro.

Science.gov (United States)

Armstead, Andrea L; Arena, Christopher B; Li, Bingyun

2014-07-01

Tungsten carbide cobalt (WC-Co) has been recognized as a workplace inhalation hazard in the manufacturing, mining and drilling industries by the National Institute of Occupational Safety and Health. Exposure to WC-Co is known to cause "hard metal lung disease" but the relationship between exposure, toxicity and development of disease remain poorly understood. To better understand this relationship, the present study examined the role of WC-Co particle size and internalization on toxicity using lung epithelial cells. We demonstrated that nano- and micro-WC-Co particles exerted toxicity in a dose- and time-dependent manner and that nano-WC-Co particles caused significantly greater toxicity at lower concentrations and shorter exposure times compared to micro-WC-Co particles. WC-Co particles in the nano-size range (not micron-sized) were internalized by lung epithelial cells, which suggested that internalization may play a key role in the enhanced toxicity of nano-WC-Co particles over micro-WC-Co particles. Further exploration of the internalization process indicated that there may be multiple mechanisms involved in WC-Co internalization such as actin and microtubule based cytoskeletal rearrangements. These findings support our hypothesis that WC-Co particle internalization contributes to cellular toxicity and suggest that therapeutic treatments inhibiting particle internalization may serve as prophylactic approaches for those at risk of WC-Co particle exposure. Copyright © 2014 Elsevier Inc. All rights reserved.

A study on erosive wear behavior of HVOF sprayed nanostructured WC-CoCr coatings

International Nuclear Information System (INIS)

Thakur, Lalit; Arora, Navneet

2013-01-01

WC-CoCr cermet coatings were deposited on stainless steel substrate using high-velocity oxy-fuel (HVOF) thermal spray process. The coatings were developed with two different thermal spray powders: one has WC grains of conventional micron size and the other is composed of nanosized (near-nanostructured) grains. HVOF spraying was assisted with in-flight particle temperature and velocity measurement system to control the process parameters that have resulted in quality coatings. Cavitation erosion testing was performed using a vibratory test apparatus based on ASTM standard G32-98. Surface morphology of powders and coatings was examined using the FESEM images, and phase identification was performed by XRD analysis. The erosion behavior of coatings and mechanism of material removal was discussed by examining the microstructure images of worn-out surfaces. WC-CoCr cermet coating deposited with nanosized WC grains exhibited higher cavitation erosion resistance as compared to conventional coating.

A study on erosive wear behavior of HVOF sprayed nanostructured WC-CoCr coatings

Energy Technology Data Exchange (ETDEWEB)

Thakur, Lalit; Arora, Navneet [Indian Institute of Technology Roorkee, Roorkee (India)

2013-05-15

WC-CoCr cermet coatings were deposited on stainless steel substrate using high-velocity oxy-fuel (HVOF) thermal spray process. The coatings were developed with two different thermal spray powders: one has WC grains of conventional micron size and the other is composed of nanosized (near-nanostructured) grains. HVOF spraying was assisted with in-flight particle temperature and velocity measurement system to control the process parameters that have resulted in quality coatings. Cavitation erosion testing was performed using a vibratory test apparatus based on ASTM standard G32-98. Surface morphology of powders and coatings was examined using the FESEM images, and phase identification was performed by XRD analysis. The erosion behavior of coatings and mechanism of material removal was discussed by examining the microstructure images of worn-out surfaces. WC-CoCr cermet coating deposited with nanosized WC grains exhibited higher cavitation erosion resistance as compared to conventional coating.

Synthesis and Multi Scale Tribological Behavior of WC-Co/Nanodiamond Nanocomposites.

Science.gov (United States)

Nieto, Andy; Jiang, Lin; Kim, Jaekang; Kim, Dae-Eun; Schoenung, Julie M

2017-08-01

Nanodiamonds (ND) present a unique combination of desirable mechanical, functional, and chemical characteristics that are ideally suited for reinforcing and enhancing the wear resistance of carbide based materials. Tungsten carbide cobalt (WC-Co) matrix nanocomposites reinforced with varying amounts of ND (2 - 10 vol.%) were synthesized here by spark plasma sintering. The rapid thermal consolidation route enabled attainment of dense samples with a significant retention of the metastable diamond phase. NDs affected the microstructural evolution, chemistry, and mechanical properties of WC-Co. Macroscale reciprocating pin-on-disk tests were conducted to assess wear behavior under conditions relevant to service environments, e.g., high cycles and high contact pressure. Microscale tribological properties were assessed using microscratch tests in order to investigate the intrinsic effects of ND on the localized mechanical and tribological response of WC-Co-ND composites. The incorporation of 10 vol.% ND enhanced wear resistance at both the micro- and macroscale, by 28% and 35%, respectively.

Effect of Load on Friction-Wear Behavior of HVOF-Sprayed WC-12Co Coatings

Science.gov (United States)

Yifu, Jin; Weicheng, Kong; Tianyuan, Sheng; Ruihong, Zhang; Dejun, Kong

2017-07-01

A WC-12Co coating was sprayed on AISI H13 hot work mold steel using a high-velocity oxygen fuel. The morphologies, phase compositions, and distributions of chemical elements of the obtained coatings were analyzed using a field emission scanning electron microscope, x-ray diffraction, and energy-dispersive spectroscope (EDS), respectively. The friction-wear behaviors under different loads were investigated using a reciprocating wear tester; the morphologies and distributions of the chemical elements of worn tracks were analyzed using a SEM and its configured EDS, respectively. The results show the reunited grains of WC are held together by the Co binder; the primary phases of the coating are WC, Co, and a small amount of W2C and W, owing to the oxidation and decarburization of WC. Inter-diffusion of Fe and W between the coating and the substrate is shown, which indicates a good coating adhesion. The values of the average coefficient of friction under the loads of 40, 80, and 120 N are 0.29, 0.31, and 0.49, respectively. The WC grains are pulled out of the coating during the sliding wear test, but the coating maintains its integrity, suggesting that the coating is intact and continuously protects the substrate from wearing.

The Synthesis of Nanostructured WC-Based Hardmetals Using Mechanical Alloying and Their Direct Consolidation

Directory of Open Access Journals (Sweden)

N. Al-Aqeeli

2014-01-01

Full Text Available Tungsten carbide- (WC- based hardmetals or cemented carbides represent an important class of materials used in a wide range of industrial applications which primarily include cutting/drilling tools and wear resistant components. The introduction and processing of nanostructured WC-based cemented carbides and their subsequent consolidation to produce dense components have been the subject of several investigations. One of the attractive means of producing this class of materials is by mechanical alloying technique. However, one of the challenging issues in obtaining the right end-product is the possible loss of the nanocrystallite sizes due to the undesirable grain growth during powder sintering step. Many research groups have engaged in multiple projects aiming at exploring the right path of consolidating the nanostructured WC-based powders without substantially loosing the attained nanostructure. The present paper highlights some key issues related to powder synthesis and sintering of WC-based nanostructured materials using mechanical alloying. The path of directly consolidating the powders using nonconventional consolidation techniques will be addressed and some light will be shed on the advantageous use of such techniques. Cobalt-bonded hardmetals will be principally covered in this work along with an additional exposure of the use of other binders in the WC-based hardmetals.

Genotoxicity of tungsten carbide-cobalt (WC-Co) nanoparticles in vitro: mechanisms-of-action studies.

Science.gov (United States)

Moche, Hélène; Chevalier, Dany; Vezin, Hervé; Claude, Nancy; Lorge, Elisabeth; Nesslany, Fabrice

2015-02-01

We showed previously that tungsten carbide-cobalt (WC-Co) nanoparticles (NP) can be used as a nanoparticulate positive control in some in vitro mammalian genotoxicity assays. Here, we investigate the mechanisms of action involved in WC-Co NP genotoxicity in L5178Y mouse lymphoma cells and primary human lymphocytes, in vitro. Data from the micronucleus assay coupled with centromere staining and from the chromosome-aberration assay show the involvement of both clastogenic and aneugenic events. Experiments with the formamidopyrimidine DNA glycosylase (FPG)-modified comet assay showed a slight (non-significant) increase in FPG-sensitive sites in the L5178Y mouse lymphoma cells but not in the human lymphocytes. Electron paramagnetic resonance spin-trapping results showed the presence of hydroxyl radicals (•OH) in WC-Co NP suspensions, with or without cells, but with time-dependent production in the presence of cells. However, a significant difference in •OH production was observed between human lymphocytes from two different donors. Using H2O2, we showed that WC-Co NP can participate in Fenton-like reactions. Thus, •OH might be produced either via intrinsic generation by WC-Co NP or through a Fenton-like reaction in the presence of cells. Copyright © 2015 Elsevier B.V. All rights reserved.

Microstructure and hardness of WC-Co particle reinforced iron matrix surface composite

Directory of Open Access Journals (Sweden)

Zhang Peng

2013-11-01

Full Text Available In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS, electron probe microanalysis (EPMA, scanning electron microscope (SEM and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle volumetric fraction of ~38%. During solidification, interface reaction takes place between WC-Co particles and high chromium cast iron. Melting and dissolving of prefabricated particles are also found, suggesting that local Co melting and diffusion play an important role in promoting interface metallurgical bonding. The composite layer is composed of ferrite and a series of carbides, such as (Cr, W, Fe23C6, WC, W2C, M6C and M12C. The inhomogeneous hardness in the obtained composite material shows a gradient decrease from the particle reinforced metal matrix composite layer to the matrix layer. The maximum hardness of 86.3 HRA (69.5 HRC is obtained on the particle reinforced surface, strongly indicating that the composite can be used as wear resistant material.

SHOCK-JR: a computer program to analyze impact response of shipping container

International Nuclear Information System (INIS)

Ikushima, Takeshi; Nakazato, Chikara; Shimoda, Osamu; Uchino, Mamoru.

1983-02-01

The report is provided for using a computer program, SHOCK-JR, which is used to analyze the impact response of shipping containers. Descriptions are the mathematical model, method of analysis, structures of the program and the input and output variables. The program solves the equations of motion for a one-dimensional, lumped mass and nonlinear spring model. The solution procedure uses Runge-Kutta-Gill and Newmark-β methods. SHOCK-JR is a revised version of SHOCK, which was developed by ORNL. In SHOCK-JR, SI dimension is used and graphical output is available. (author)

Catalytic activity of tungsten carbide-carbon (WC@C) core-shell structured for ethanol electro-oxidation

Energy Technology Data Exchange (ETDEWEB)

Singla, Gourav, E-mail: gsinghla@gmail.com; Singh, K., E-mail: kusingh@thapar.edu; Pandey, O.P., E-mail: oppandey@thapar.edu

2017-01-15

In this study, carbon coated WC (WC@C) was synthesized through solvothermal reactions in the presence of reducing agent magnesium (Mg) by employing tungsten oxide (WO{sub 3}) as a precursor, acetone (C{sub 3}H{sub 6}O) as a carbon source. The formation of WC@C nano particles is confirmed by X-ray diffraction and Transmission electron microscopy. The thermal stability of the synthesized powder examined in air shows its stability up to 550 °C. In this method, in-situ produced outer carbon layer increase the surface area of materials which is 52.6 m{sup 2} g{sup −1} with pore volume 0.213 cm{sup 3} g{sup −1}. The Electrocatalytic activity of ethanol oxidation on a synthesized sample with and without Pt nano particles have been investigated using cyclic voltammetry (CV). The CV results show the enhancement in oxidation stability of WC@C in acidic media as well as better CO-tolerance for ethanol oxidation after the deposition of Pt nanoparticles as compared to without Pt nano particles. - Highlights: • Tungsten carbide nano powder was synthesized using acetone as carbon source. • In-situ produced outer carbon layer increase the surface area of materials. • Mesoporous WC with surface areas 52.6 m{sup 2}/g obtained. • Pt modified WC powder showed higher electrochemical stability. • Better CO-tolerance for ethanol oxidation after the deposition of Pt nanoparticles.

Hydrogen effects in anodic grinding of WC-Co sintered alloy

International Nuclear Information System (INIS)

Lunarska, E.; Zaborski, St.

2001-01-01

The effects of anodic polarization applied in grinding of sintered WC C o alloy on properties of surface layer, quality of ground surface and efficiency of the treatment were studied. The nonmonotonical change of the surface roughness, the energy consumption and the wear of tool was stated at increasing anodic polarization. The optimum values of above parameters were achieved at application of anodic polarization at which the Co selective dissolution and hydrogen ingress into the ground metal. affecting the internal friction spectra were stated. The assistance of hydrogen induced deterioration and Co selective dissolution in the surface layer in the anodic grinding of WC-Co alloy has been discussed. (author)

Pt-Ni/WC Alloy Nanorods Arrays as ORR Catalyst for PEM Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Begum, Mahbuba; Yurukcu, Mesut; Yurtsever, Fatma; Ergul, Busra; Kariuki, Nancy; Myers, Deborah J.; Karabacak, Tansel

2017-08-24

Polymer electrolyte membrane fuel cells (PEMFCs) among the other types of fuel cell technology are attractive power sources, especially for electric vehicle applications. While significant progress and plausible prospects of PEMFCs have been achieved, there are still some challenges related to the performance, durability, and cost that need to be overcome to make them economically viable for widespread commercialization. Our strategy is to develop thin films of high-active and stable catalyst coated on vertically aligned nanorod arrays of conductive and stable support. In this work, we fabricated tungsten carbide (WC) nanorods as support and coated them with a platinum-nickel (Pt-Ni) alloy shell denoted as Pt-Ni/WC catalysts. The Pt- Ni/WC nanorods were deposited on glassy carbon disks as well as on silicon substrates for evaluation of their electrocatalytic oxygen reduction reaction (ORR) activity and physical properties. Cyclic voltammetry experiments using rotating disk electrode were performed in perchloric acid (0.1 M HClO4) electrolyte at room temperature to characterize the ORR activity and stability of Pt-Ni/WC nanorods catalysts. Scanning electron microscopy and X-ray diffraction techniques were utilized to study the morphology and crystallographic properties, respectively.

Measuring c-quark polarization in W+c samples at ATLAS and CMS

CERN Document Server

Kats, Yevgeny

2016-01-01

The process $pp \\to W^-c$ produces polarized charm quarks. The polarization is expected to be partly retained in $\\Lambda_c$ baryons when those form in the $c$-quark hadronization. We argue that it will likely be possible for ATLAS and CMS to measure the $\\Lambda_c$ polarization in the $W$+$c$ samples in Run 2 of the LHC. This can become the first measurement ever of a longitudinal polarization of charm quarks. Its results will provide a unique input to the understanding of polarization transfer in fragmentation. They will also allow applying the same measurement technique to other (e.g., new physics) samples of charm quarks in which the polarization is a priori unknown. The proposed analysis is similar to the ATLAS and CMS measurements of the $W$+$c$ cross section in the 7 TeV run that used reconstructed $D$-meson decays for charm tagging.

Evaluation of WC-9Co-4Cr laser surface alloyed coatings on stainless steel

CSIR Research Space (South Africa)

Obadele, A

2011-07-01

Full Text Available spectrometer (EDS), while the phase changed were observed using x-ray diffraction (XRD). The surface hardness was determined using the Vickers microhardness tester. The decomposition of WC-9Co-4Cr into W2C, C and W is as a result of low heat of formation of WC...

Nanotoxicity: emerging concerns regarding nanomaterial safety and occupational hard metal (WC-Co nanoparticle exposure

Directory of Open Access Journals (Sweden)

Armstead AL

2016-12-01

Full Text Available Andrea L Armstead,1,2 Bingyun Li1–3 1Department of Orthopaedics, School of Medicine, 2School of Pharmacy, West Virginia University, 3Mary Babb Randolph Cancer Center, Morgantown, WV, USA Abstract: As the number of commercial and consumer products containing engineered nanomaterials (ENMs continually rises, the increased use and production of these ENMs presents an important toxicological concern. Although ENMs offer a number of advantages over traditional materials, their extremely small size and associated characteristics may also greatly enhance their toxic potentials. ENM exposure can occur in various consumer and industrial settings through inhalation, ingestion, or dermal routes. Although the importance of accurate ENM characterization, effective dosage metrics, and selection of appropriate cell or animal-based models are universally agreed upon as important factors in ENM research, at present, there is no “standardized” approach used to assess ENM toxicity in the research community. Of particular interest is occupational exposure to tungsten carbide cobalt (WC-Co “dusts,” composed of nano- and micro-sized particles, in hard metal manufacturing facilities and mining and drilling industries. Inhalation of WC-Co dust is known to cause “hard metal lung disease” and an increased risk of lung cancer; however, the mechanisms underlying WC-Co toxicity, the inflammatory disease state and progression to cancer are poorly understood. Herein, a discussion of ENM toxicity is followed by a review of the known literature regarding the effects of WC-Co particle exposure. The risk of WC-Co exposure in occupational settings and the updates of in vitro and in vivo studies of both micro- and nano-WC-Co particles are discussed. Keywords: engineered nanomaterial, occupational exposure, lung disease, cancer, toxicity, particle

Martin Luther King Jr. contest winning posters to be displayed in downtown Blacksburg

OpenAIRE

Shannon, Kelly Baker

2010-01-01

Each year as part of the Martin Luther King Jr. celebration at Virginia Tech area kindergarten through 12th grade students are invited to participate in the annual Martin Luther King Jr. poster contest.

Physico-chemical profiles of the wobble ↔ Watson-Crick G*·2AP(w) ↔ G·2AP(WC) and A·2AP(w) ↔ A*·2AP(WC) tautomerisations: a QM/QTAIM comprehensive survey.

Science.gov (United States)

Brovarets', Ol'ha O; Voiteshenko, Ivan S; Hovorun, Dmytro M

2017-12-20

This study is intended to clarify in detail the tautomeric transformations of the wobble (w) G*·2AP(w) and A·2AP(w) nucleobase mispairs involving 2-aminopurine (2AP) into the Watson-Crick (WC) G·2AP(WC) and A*·2AP(WC) base mispairs (asterisks denote mutagenic tautomers of the DNA bases), respectively, by quantum-mechanical methods and Bader's Quantum Theory of Atoms in Molecules. Our previously reported methodology has been used, which allows the evolution of the physico-chemical parameters to be tracked along the entire internal reaction coordinate (IRC), not exclusively in the stationary states of these reactions. These biologically important G*·2AP(w) ↔ G·2AP(WC) and A·2AP(w) ↔ A*·2AP(WC) w ↔ WC tautomerisations, which are involved in mutagenic tautomerically-conformational pathways, determine the origin of the transitions and transversions induced by 2AP. In addition, it is established that they proceed through planar, highly stable, zwitterionic transition states and they exhibit similar physico-chemical profiles and stages of sequential intrapair proton transfer, followed by spatial rearrangement of the nucleobases relative to each other within the base pairs. These w ↔ WC tautomerisations occur non-dissociatively and are accompanied by a significant alteration in geometry (from wobble to Watson-Crick and vice versa) and redistribution of the specific intermolecular interactions, which can be divided into 10 patterns including AHB H-bonds and loosened A-H-B covalent bridges along the IRC of tautomerisation. Based on the redistribution of the geometrical and electron-topological parameters of the intrapair hydrogen bonds, exactly 9 key points have been allocated to characterize the evolution of these reactions.

Tribological behavior of Al-WC nano-composites fabricated by ultrasonic cavitation assisted stir-cast method

Science.gov (United States)

Pal, Arpan; Poria, Suswagata; Sutradhar, Goutam; Sahoo, Prasanta

2018-03-01

In the present study, the effects of WC nano-particles content on the microstructure, hardness, wear, and friction behavior of aluminum matrix composites are investigated. Al-WC nano composites with varying wt% of WC (0, 1, 1.5, and 2) are fabricated using ultrasonic cavitation assisted stir-cast method. The microstructure of the nano-composite samples is analyzed using optical microscopy and scanning electron microscopy. Elemental composition is determined by energy dispersive x-ray analysis. Vicker’s microhardness test is performed in different locations on the composite sample surface with a load of 50 gf and 10s dwell time. Wear and friction of the composites under dry sliding is studied using a pin-on-disk tribotester for varying normal load (10–40 N) and sliding speed (0.1–0.4 m/s). Uniform distribution of nano-WC is observed over composite surface without noticeable clustering. Reinforcement of nano-WC particles improves wear resistance and frictional behavior of the composite. Hardness is seen to increase with increase in wt% of nano-particles. Wear behavior of composites depends on formation of layers over the surface mixed with oxidized debris and counter-face particles. Wear mechanism changes from adhesion to abrasion with increase in wt% of hard nano particles.

Comparative study of the friction and wear behavior of plasma sprayed conventional and nanostructured WC-12%Co coatings on stainless steel

International Nuclear Information System (INIS)

Zhao Xiaoqin; Zhou Huidi; Chen Jianmin

2006-01-01

Conventional and nanostructured WC-12%Co coatings were deposited on 1Cr18Ni9Ti stainless steel substrate using air plasma spraying. The hardness of the coatings was measured, while their friction and wear behavior sliding against Si 3 N 4 at room temperature and elevated temperatures up to 400 deg. C was comparatively studied. The microstructures and worn surface morphologies of the coatings were comparatively analyzed as well by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA). It was found that the as-sprayed WC-12%Co coatings were composed of WC as the major phase and W 2 C, WC 1-x , and W 3 Co 3 C as the minor phases. The plasma sprayed nanostructured WC-12%Co coating had much higher hardness and refined microstructures than the conventional WC-12%Co coating. This largely accounted for the better wear resistance of the nanostructured WC-12%Co coating than the conventional coating. Besides, the two types of WC-12%Co coatings showed minor differences in friction coefficients, though the nanostructured WC-12%Co coating roughly had slightly smaller friction coefficient than the conventional coating under the same sliding condition. Moreover, both the conventional and nanostructured WC-12%Co coatings recorded gradually increased wear rate with increasing temperature, and the nanostructured coating was less sensitive to the temperature rise in terms of the wear resistance. The worn surfaces of the conventional WC-12%Co coating at different sliding conditions showed more severe adhesion, microfracture, and peeling as compared to the nanostructured WC-12%Co coating, which well conformed to the corresponding wear resistance of the two types of coatings. The nanostructured WC-12%Co coating with a wear rate as small as 1.01 x 10 -7 mm 3 /Nm at 400 deg. C could be promising candidate coating for the surface-modification of some sliding components subject to harsh working conditions involving elevated

Views of Dr. Martin Luther King, Jr.

Science.gov (United States)

Davis, Alan H.

1990-01-01

Discusses views of Martin Luther King, Jr., including concepts of human rights, related counseling approaches, and ethics. Claims King's views provide helpful insights for counselors and clients. Concludes King invited individuals to view challenging life situations as moral opportunities. (Author/ABL)

Letters of Second Lieutenant Charles Wesley Chapman, Jr. December 19, 1894 - May 3, 1918

Science.gov (United States)

2016-04-01

that every possible channel of communication will be utilized to ascertain the whereabouts of your son. The personal effects of 2nd. Lieut. Charles W...AIR UNIVERSITY AIR FORCE RESEARCH INSTITUTE Letters of Second Lieutenant Charles Wesley Chapman, Jr. December 19, 1894–May 3, 1918 Air Force...in-Publication Data Chapman, Charles Wesley, Jr., 1894–1918. Letters of Second Lieutenant Charles Wesley Chapman, Jr., December 19, 1894–May 3, 1918

78 FR 57105 - Wm. Wrigley Jr. Company; Filing of Color Additive Petition

Science.gov (United States)

2013-09-17

... lead in synthetic iron oxide for human food use. DATES: The color additive petition was filed on July.... FDA-2013-C-1008] Wm. Wrigley Jr. Company; Filing of Color Additive Petition AGENCY: Food and Drug... announcing that we have filed a petition, submitted by the Wm. Wrigley Jr. Company, proposing that the color...

An alternative approach to estimate the W/C ratio of hardened concrete using image analysis

NARCIS (Netherlands)

Valcke, S.; Nijland, T.G.; Larbi, J.A.

2009-01-01

The water cement (w/c) ratio is a typical quality parameter for concrete. The NT Build 361 Nordtest method is a standard for estimating the w/c ratio in hardened concrete and is based on the relationship between the ilc ratio and the capillary porosity in the cement paste. The latter can be

COBRA-WC: a version of COBRA for single-phase multiassembly thermal hydraulic transient analysis

International Nuclear Information System (INIS)

George, T.L.; Basehore, K.L.; Wheeler, C.L.; Prather, W.A.; Masterson, R.E.

1980-07-01

The objective of this report is to provide the user of the COBRA-WC (Whole Core) code a basic understanding of the code operation and capabilities. Included in this manual are the equations solved and the assumptions made in their derivations, a general description of the code capabilities, an explanation of the numerical algorithms used to solve the equations, and input instructions for using the code. Also, the auxiliary programs GEOM and SPECSET are described and input instructions for each are given. Input for COBRA-WC sample problems and the corresponding output are given in the appendices. The COBRA-WC code has been developed from the COBRA-IV-I code to analyze liquid Metal Fast Breeder Reactor (LMFBR) assembly transients. It was specifically developed to analyze a core flow coastdown to natural circulation cooling

Investigation of aperiodic W/C multi-layer mirror for X-ray optics

International Nuclear Information System (INIS)

Wang Zhanshan; Cheng Xinbin; Zhu Jingtao; Huang Qiushi; Zhang Zhong; Chen Lingyan

2011-01-01

Design, fabrication and characterization of aperiodic tungsten/carbon (W/C) multi-layer mirror were studied. W/C multi-layer was designed as a broad-angle reflective supermirror for Cu-Kα line (λ = 0.154 nm) in the grazing incident angular range (0.9-1.1 deg.) using simulated annealing algorithm. To deposit the W/C depth-graded multi-layer mirror accurately, we introduce an effective layer growth rate as a function of layer thickness. This method greatly improves the reflectivity curve compared to the conventional multi-layer mirror prepared with constant growth rate. The deposited multi-layer mirror exhibits an average reflectivity of 19% over the grazing incident angle range of 0.88-1.08 deg. which mainly coincides with the designed value. Furthermore, the physical mechanisms were discussed and the re-sputtering process of light-atom layers is accounted for the modification of layer thicknesses which leads to the effective growth rates. Using this calibration method, the aperiodic multi-layer mirrors can be better fabricated for X-ray optics.

Religión y Paz en Martin Luther King Jr.

OpenAIRE

Mussio, Ria Stacy

2016-01-01

Esta tesis pretende mostrar el rol integral que la religión desempeñaba en la obtención de los derechos civiles para los afroamericanos y, también en el logro de la paz positiva. Martin Luther King Jr. y la mayoría de los manifestantes del movimiento eran cristianos, poniendo su fe en Dios, para el pleno disfrute de sus derechos humanos. King Jr., anclado en su fe, impulsó el avance de los derechos civiles, mediante la resistencia no violenta. El primer capítulo tiene como finalidad orientar ...

Claim on memory : a political biography of Franklin D. Roosevelt, Jr., 1914-1988

NARCIS (Netherlands)

Berg, Erik Eduard Willem van den

2006-01-01

This dissertation focuses on the political life of Franklin D. Roosevelt, Jr., the third surviving son of Franklin D. Roosevelt and Eleanor Roosevelt. The key question of this study emphasizes how FDR, Jr. interpreted the Roosevelt name and legacy during his life and political career. This book

3 CFR 8340 - Proclamation 8340 of January 15, 2009. Martin Luther King, Jr., Federal Holiday, 2009

Science.gov (United States)

2010-01-01

... Proclamation 8340 of January 15, 2009 Proc. 8340 Martin Luther King, Jr., Federal Holiday, 2009By the President of the United States of America A Proclamation On the Martin Luther King, Jr., Federal Holiday, we... Constitution and laws of the United States, do hereby proclaim January 19, 2009, as the Martin Luther King, Jr...

1997 Arthur Ashe Jr. Sport Scholars Awards.

Science.gov (United States)

Roach, Ronald

1997-01-01

Winners of the "Black Issues in Higher Education" Arthur Ashe Jr. 1997 athletes of the year, one male and one female, are profiled and Sport Scholars are listed for baseball, softball, basketball, fencing, archery, football, handball, soccer, field hockey, crew, swimming, gymnastics, tennis, squash, golf, volleyball, lacrosse, wrestling, water…

Analysis of PTA hardfacing with CoCrWC and CoCrMoSi alloys

Directory of Open Access Journals (Sweden)

Adriano Scheid

2013-12-01

Full Text Available CoCrWC alloys are widely used to protect components that operate under wear and high temperature environments. Enhanced performance has been achieved with the CoCrMoSi alloys but processing this alloy system is still a challenge due to the presence of the brittle Laves phase, particularly when welding is involved. This work evaluated Plasma Transferred Arc coatings processed with the Co-based alloy CoMoCrSi - Tribaloy T400, reinforced with Laves phase, comparing its weldability to the CoCrWC - Stellite 6, reinforced with carbides. Coatings were also analyzed regarding the response to temperature exposure at 600°C for 7 days and subsequent effect on microstructure and sliding abrasive wear. Coatings characterization was carried out by light and scanning electron microscopy, X-ray diffraction and Vickers hardness. CoCrWC coatings exhibited a Cobalt solid solution dendritic microstructure and a thin interdendritic region with eutectic carbides, while CoCrMoSi deposits exhibit a large lamellar eutectic region of Laves phase and Cobalt solid solution and a small fraction of primary Laves phase. Although phase stability was observed by X-ray diffraction, coarsening of the microstructure occurred for both alloys. CoCrMoSi showed thicker lamellar Laves phase and CoCrWC coarser eutectic carbides. Coatings stability assessed by wear tests revealed that although the wear rate of the as-deposited CoCrMoSi alloy was lower than that of CoCrWC alloy its increase after temperature exposure was more significant, 22% against 15%. Results were discussed regarding the protection of industrial components in particular, bearings in 55AlZn hot dip galvanizing components.

Critical Damage Analysis of WC-Co Tip of Conical Pick due to Coal Excavation in Mines

Directory of Open Access Journals (Sweden)

Saurabh Dewangan

2015-01-01

Full Text Available WC-Co based tools are widely used in the field of coal and rock excavation because of their unique combination of strength, hardness, and resistance to abrasive wear. Conical pick is one of the coal cutting tools. The tip of the pick is made of WC-Co material. As coal and rock are heterogeneous elements, they pose various constraints during excavation. As a result the tools wear out during the process. Other parameters like cutting techniques, tool orientation, and environmental conditions also affect the tool significantly. The wearing phenomenon greatly reduces the service life of the tools and thereby cuts down the production rate. To prevent such wearing process, it is important to investigate the different wear mechanisms in WC-Co. Simultaneously, there has to be an ongoing endeavour for the development of better quality WC-Co. This paper focuses on different wear mechanisms in a conical pick which has been used in a continuous miner machine for coal cutting. The worn out surface has been observed by using FE-SEM (field emission scanning electron microscopy and EDS (energy dispersive X-ray spectroscopy. The mechanisms, namely, coal/rock intermixing, cracking and crushing of WC grains, and adhesion of rock particles, have been predominantly investigated in this study. A little indication of corrosive decay in the WC grain has also been reported. The EDS has detected material concentration in a selected area or point of the worn-out surface. The spectrograph confirms the presence of coal/rock materials. Elements such as W, C, Ca, K, O, and Co have been mainly found in different concentrations at different positions.

Mechanical Properties and Wear Behavior of AA5182/WC Nanocomposite Fabricated by Friction Stir Welding at Different Tool Traverse Speeds

Science.gov (United States)

Paidar, Moslem; Asgari, Ali; Ojo, Olatunji Oladimeji; Saberi, Abbas

2018-03-01

Grain growth inhibition at the heat-affected zone, improved weld strength and superior tribological properties of welds are desirable attributes of modern manufacturing. With the focused on these attributes, tungsten carbide (WC) nanoparticles were employed as reinforcements for the friction stir welding of 5-mm-thick AA5182 aluminum alloy by varying tool traverse speeds. The microstructure, microhardness, ultimate tensile strength, fracture and wear behavior of the resultant WC-reinforced welds were investigated, while unreinforced AA5182 welds were employed as controls for the study. The result shows that the addition of WC nanoparticles causes substantial grain refinement within the weld nugget. A decrease in traverse speed caused additional particle fragmentation, improved hardness value and enhanced weld strength in the reinforced welds. Improved wear rate and friction coefficient of welds were attained at a reduced traverse speed of 100 mm/min in the WC-reinforced welds. This improvement is attributed to the effects of reduced grain size/grain fragmentation and homogeneous dispersion of WC nanoparticles within the WC-reinforced weld nugget.

Performance and characterisation of CVD diamond coated, sintered diamond and WC-Co cutting tools for dental and micromachining applications

International Nuclear Information System (INIS)

Sein, Htet; Ahmed, Waqar; Jackson, Mark; Woodwards, Robert; Polini, Riccardo

2004-01-01

Diamond coatings are attractive for cutting processes due to their high hardness, low friction coefficient, excellent wear resistance and chemical inertness. The application of diamond coatings on cemented tungsten carbide (WC-Co) tools was the subject of much attention in recent years in order to improve cutting performance and tool life. WC-Co tools containing 6% Co and 94% WC substrate with an average grain size 1-3 μm were used in this study. In order to improve the adhesion between diamond and WC substrates, it is necessary to etch away the surface Co and prepare the surface for subsequent diamond growth. Hot filament chemical vapour deposition with a modified vertical filament arrangement has been employed for the deposition of diamond films. Diamond film quality and purity have been characterised using scanning electron microscopy and micro-Raman spectroscopy. The performance of diamond coated WC-Co bur, uncoated WC-Co bur, and diamond embedded (sintered) bur have been compared by drilling a series of holes into various materials such as human teeth, borosilicate glass and porcelain teeth. Flank wear has been used to assess the wear rates of the tools. The materials subjected to cutting processes have been examined to assess the quality of the finish. Diamond coated WC-Co microdrills and uncoated microdrills were also tested on aluminium alloys. Results show that there was a 300% improvement when the drills were coated with diamond compared to the uncoated tools

CVD of alternated microcrystalline (MCD) and nanocrystalline (NCD) diamond films on WC-TIC-CO substrates

International Nuclear Information System (INIS)

Campos, Raonei Alves; Contin, Andre; Trava-Airoldi, Vladimir J.; Corat, Evaldo Jose; Barquete, Danilo Maciel

2010-01-01

CVD Diamond coating of WC-TiC-Co cutting tools has been an alternative to increase tool lifetime. Experiments have shown that residual stresses produced during films growth on WC-TiC-Co substrates significantly increases with increasing film thickness up to 20 μm and usually leads to film delamination. In this work alternated micro- and nanocrystalline CVD diamond films have been used to relax interface stresses and to increase diamond coatings performance. WC-TiC-Co substrates have been submitted to a boronizing thermal diffusion treatment prior to CVD diamond films growth. After reactive heat treatment samples were submitted to chemical etching in acid and alkaline solution. The diamond films deposition was performed using HFCVD reactor with different gas concentrations for microcrystalline (MCD) and nano-crystalline (NCD) films growth. As a result, we present the improvement of diamond films adherence on WC-TiC-Co, evaluated by indentation and machining tests. Samples were characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) for qualitative analysis of diamond films. X-ray Diffraction (XRD) was used for phases identification after boronizing process. Diamond film compressive residual stresses were analyzed by Raman Scattering Spectroscopy (RSS). (author)

Karl A. Gschneidner Jr (1930–2016)

International Nuclear Information System (INIS)

Pecharsky, Vitalij K.

2016-01-01

Presented here is the obituary for Karl Albert Gschneidner Jr. He died on 27 April 2016. Nicknamed Mr Rare Earth, he holds an unparalleled place as the renowned authority in just about every aspect related to the science, technology and history of a very special family of elements — the rare earths.

Regularities of structure formation on different stages of WC-Co hard alloys fabrication

Energy Technology Data Exchange (ETDEWEB)

Chernyavskij, K S

1987-03-01

Some regularities of structural transformations in powder products of the hard alloys fabrication have been formulated on the basis of results of the author works and other native and foreign reseachers. New data confirming the influene of technological prehistory of carbide powder on the mechanism of its particle grinding as well as the influence of the structural-energy state of WC powder on the course of the WC-Co alloy structure formation processes are given. Some possibilities for the application in practice of the regularities studied are considered.

Anisotropic atomic packing model for abnormal grain growth mechanism of WC-25 wt.% Co alloy

International Nuclear Information System (INIS)

Ryoo, H.S.; Hwang, S.K.

1998-01-01

During liquid phase sintering, cemented carbide particles grow into either faceted or non-faceted grain shapes depending on ally system. In case of WC-Co alloy, prism-shape faceted grains with (0001) planes and {1 bar 100} planes on each face are observed, and furthermore an abnormal grain growth has been reported to occur. When abnormal grain growth occurs in WC crystals, dimension ratio, R, of the length of the side of the triangular prism face to the height of the prism is higher than 4 whereas that for normal grains is approximately 2. Abnormal grain growth in this alloy is accelerated by the fineness of starting powders and by high sintering temperature. To account for the mechanism of the abnormal grain growth, there are two proposed models which drew much research attention: nucleation and subsequent carburization and transformation of η (W 3 Co 3 C) phase into WC, and coalescence of coarse WC grains through dissolution and re-precipitation. Park et al. proposed a two-dimensional nucleation theory to explain the abnormal grain growth of faceted grains. There are questions, however, on the role of η phase on abnormal grain growth. The mechanism of coalescence of spherical grains as proposed by Kingery is also unsuitable for faceted grains. So far theories on abnormal grain growth do not provide a satisfactory explanation on the change of R value during the growth process. In the present work a new mechanism of nucleation and growth of faceted WC grains is proposed on the ground of anisotropic packing sequence of each atom

Prediction of crack paths in WC-Co alloys

International Nuclear Information System (INIS)

Spiegler, R.; Fischmeister, H.F.

1992-01-01

This paper reports on a crack propagating through the WC-o microstructure which has to choose between paths along the binder/carbide interface and paths across binder regions. The latter paths are selected when the crack enters a binder region at a large angle from the nearest carbide interface, while the interface paths are preferred by cracks entering at a small angle. A critical angle can be defined for the switch from one type of crack path to the other. Empirical data for the area fractions of the two crack paths in widely different WC-Co alloys can be accounted for by a single critical angle, var-phi c = 25 degrees. Finite element analysis of the stress field in a region of binder enclosed between carbide grains shows that the preferred site for the growth of stress-induced microvoids will move from the carbide grain flanks to the interior of the binder region when the entry angle of the crack exceeds 24 degrees. Thus the observation of a critical angle deciding the crack path is verified by the stress field analysis and given a physical explanation in terms of the most likely site for microvoid formation

Comparative studies on mechanical properties of WC-Co composites sintered by SPS and conventional techniques

Directory of Open Access Journals (Sweden)

Pristinskiy Yuri

2017-01-01

Full Text Available Spark plasma sintering (SPS is an extremely fast solidification technique for compounds that are difficult to sinter within the material group metals, ceramics, or composites thereof, SPS uses a uniaxial pressure and a very rapid heating cycle to consolidate these materials. With SPS the main benefit is the ability to control the WC grain size due to the short sintering times at high temperature. Additionally, its allows to avoid negative reactions between WC and cobalt and to minimize the formation of undesirable phases in sintered composites. The WC-6wt.% Co cermet prepared by SPS processing achieves the enhanced mechanical properties with the hardness of 18.3 GPa and the fracture toughness of 15.5 MPa·m1/2 in comparison to standard reference tungsten carbide/cobalt material.

The Electro-Spark Deposited WC-Cu Coatings Modified by Laser Treatment / Powłoki WC-Cu Naniesione Elektroiskrowo I Modyfikowane Obróbką Laserową

Directory of Open Access Journals (Sweden)

Radek N.

2015-12-01

Full Text Available The main objective of the present work was to determine the influence of laser treatment on microstructure, X-ray diffraction, microhardness, surface geometric structure and roughness, corrosion resistance and tribological properties of coatings deposited on C45 carbon steel by the electro-spark deposition (ESD process. The studies were conducted using WC-Cu electrodes produced by the powder metallurgy route. The tests show that the laser-treated electro-spark deposited WC-Cu coatings are characterized by higher corrosion resistance, surface roughness and seizure resistance which come at the expense of lower microhardness. The laser treatment process causes the homogenization of the chemical composition, structure refinement and healing of microcracks and pores of the electro-spark deposited coatings. Laser treated ESD coatings can be applied in sliding friction pairs and as protective coatings.

Direct laser metal deposition of WC/Co/Cr powder by means of the functionally graded materials strategy

Science.gov (United States)

Angelastro, A.; Campanelli, S. L.

2017-12-01

One of the many applications of direct laser metal deposition (DLMD) is the realization of multilayer thick coatings having particular mechanical characteristics, such as high hardness. The objective of this work was to obtain a thick, very hard and wear resistant coating, containing a high percentage of tungsten carbide (WC), on an AISI 304 stainless steel substrate. In order to achieve this result, a tungsten carbide-cobalt-chrome (WC/Co/Cr) powder was processed by the DLMD method. WC/Co/Cr is a composite widely used as a wear-resistant material for cutting tools, molds, coatings and other severe applications. Because of its high hardness, poor ductility and low thermal expansion coefficient, depositing this material directly on the stainless steel substrate is very difficult. In order to overcome this problem, the strategy of functionally graded materials (FGM) was used. Colmonoy 227-F nickel alloy was chosen for this purpose in order to generate a mixture with the WC/Co/Cr powder. Four different materials were deposited, layer by layer, by mixing Colmonoy 227-F with an increasing amount of WC/Co/Cr powders, until obtaining a thick surface coating with a maximum amount of WC of 77.4 wt%. For each powder mixture, a mathematical model was applied to calculate optimal values of translation speed and overlap percentages. A metallographic examination was performed in order to detect macro- and micro-structures of the different materials. Finally, Vickers micro-hardness was measured at various locations along the transverse section to appreciate the gradual increase of the FGM hardness, starting from the substrate and culminating at the top surface of the last deposited material.

PCB extraction from ORNL tank WC-14 using a unique solvent

International Nuclear Information System (INIS)

Bloom, G.A.; Lucero, A.J.; Koran, L.J.; Turner, E.N.

1995-09-01

This report summarizes the development work of the Engineering Development Section of the Chemical Technology Division at Oak Ridge National Laboratory (ORNL) for an organic extraction method for removing polychlorinated biphenyls (PCBs) from tank WC-14. Tank WC-14 is part of the ORNL liquid low-level radioactive tank waste system and does not meet new secondary containment and leak detection regulations. These regulations require the tank to be taken out of service, and remediated before tank removal. To remediate the tank, the PCBs must be removed; the tank contents can then be transferred to the Melton Valley Storage Tanks before final disposal. The solvent being used for the PCB extraction experiments is triethylamine, an aliphatic amine that is soluble in water below 60 degrees F but insoluble in water above 90 degrees F. This property will allow the extraction to be carried out under fully miscible conditions within the tank; then, after tank conditions have been changed, the solvent will not be miscible with water and phase separation will occur. Phase separation between sludge, water, and solvent will allow solvent (loaded with PCBs) to be removed from the tank for disposal. After removing the PCBs from the sludge and removing the sludge from the tank, administrative control of the tank can be transferred to ORNL's Environmental Restoration Program, where priorities will be set for tank removal. Experiments with WC-14 sludge show that greater than 90% extraction efficiencies can be achieved with one extraction stage and that PCB concentration in the sludge can be reduced to below 2 ppm in three extractions. It is anticipated that three extractions will be necessary to reduce the PCB concentration to below 2 ppm during field applications. The experiments conducted with tank WC-14 sludge transferred less than 0.03% of the original alpha contamination and less than 0.002% of the original beta contamination

Modification of WC-Co Hard Metal by Ion Implantation with Ti+, AI+, N+, C+ and B+

International Nuclear Information System (INIS)

Rassoul, El.M.A.; Saleh, Z.A.; Waheed, A.F.; Abdel- Samad, S.M.; EI- Awadi, G.A.

2010-01-01

WC/Co hard metal was implanted by Ti + , AI + , N + , C + , and B + ions at a dose of 5x 10 17 ions/cm 2 at different energies ranging from 50 keV to 200 keV. The implanted layers were investigated by means of nano indentation, calotte measurements, SEM, X-ray diffraction XRD, tribometer and EDX. The maximum implanted zone was about 0.13 μm. The hardness of WC-Co was increased by a factor of 140% after its implantation by Ti, AI, and N and increased by a factor of 170 % after implantation by Ti + , AI + , C + , N + and B + ions as compared to the original value. Also friction coefficient of WC/Co was improved after ion implantation.

Wear Evaluation of AISI 4140 Alloy Steel with WC/C Lamellar Coatings Sliding Against EN 8 Using Taguchi Method

Science.gov (United States)

Kadam, Nikhil Rajendra; Karthikeyan, Ganesarethinam

2016-10-01

The purpose of the experiments in this paper is to use the Taguchi methods to investigate the wear of WC/C coated nitrided AISI 4140 alloy steel. A study of lamellar WC/C coating which were deposited by a physical vapor deposition on nitrided AISI 4140 alloy steel. The investigation includes wear evaluation using Pin-on-disk configuration. When WC/C coated AISI 4140 alloy steel slides against EN 8 steel, it was found that carbon-rich coatings show much lower wear of the countersurface than nitrogen-rich coatings. The results were correlated with the properties determined from tribological and mechanical characterization, therefore by probably selecting the proper processing parameters the deposition of WC/C coating results in decreasing the wear rate of the substrate which shows a potential for tribological application.

Atomic composition of WC/ and Zr/O-terminated diamond Schottky interfaces close to ideality

Energy Technology Data Exchange (ETDEWEB)

Piñero, J.C., E-mail: josecarlos.pinero@uca.es [Dpto. Ciencias de los Materiales, Universidad de Cádiz, Puerto Real, Cádiz,11510 (Spain); Araújo, D. [Dpto. Ciencias de los Materiales, Universidad de Cádiz, Puerto Real, Cádiz,11510 (Spain); Fiori, A. [National Institute for Materials Science, Tsukuba, Ibaraki (Japan); Traoré, A. [Institut Néel, CNRS-UJF, av. des Martyrs, Grenoble,38042 France (France); Villar, M.P. [Dpto. Ciencias de los Materiales, Universidad de Cádiz, Puerto Real, Cádiz,11510 (Spain); Eon, D.; Muret, P.; Pernot, J. [Institut Néel, CNRS-UJF, av. des Martyrs, Grenoble,38042 France (France); Teraji, T. [National Institute for Materials Science, Tsukuba, Ibaraki (Japan)

2017-02-15

Highlights: • Metal/O-terminated diamond interfaces are analyzed by a variety of TEM techniques. • Thermal treatment is shown to modify structural and chemical interface properties. • Electrical behavior vs annealing is shown to be related with interface modification. • Interfaces are characterized with atomic resolution to probe inhomogeneities. • Oxide formation and modification is demonstrated in both Schottky diodes. - Abstract: Electrical and nano-structural properties of Zr and WC-based Schottky power diodes are compared and used for investigating oxide-related effects at the diamond/metal interface. Differences in Schottky barrier heights and ideality factors of both structures are shown to be related with the modification of the oxygen-terminated diamond/metal interface configuration. Oxide formation, oxide thickness variations and interfacial oxygen redistribution, associated with thermal treatment are demonstrated. Ideality factors close to ideality (n{sub WC} = 1.02 and n{sub Zr} = 1.16) are obtained after thermal treatment and are shown to be related with the relative oxygen content at the surface (OCR{sub WC} = 3.03 and OCR{sub Zr} = 1.5). Indeed, thermal treatment at higher temperatures is shown to promote an escape of oxygen for the case of the WC diode, while it generates a sharper accumulation of oxygen at the metal/diamond interface for the case of Zr diode. Therefore, the metal-oxygen affinity is shown to be a key parameter to improve diamond-based Schottky diodes.

Fundamentals of grinding : surface conditions of ground WC-Co systems

NARCIS (Netherlands)

Hegeman, JBJW; De Hosson, JTM; Shulepov, SY; Lousberg, N; de With, G; Brebbia, CA; Kenny, JM

1999-01-01

This paper concentrates on the fundamentals of grinding of inorganic materials. A statistical grinding model was developed based on the topography of the grinding wheel. The results of the model are compared with the results of grinding experiments on WC-Co hardmetals. The calculated profiles and

Fabrication of hard cermets by in-situ synthesis and infiltration of metal melts into WC powder compacts

Directory of Open Access Journals (Sweden)

Guanghua Liu

2017-12-01

Full Text Available Hard carbide cermets are prepared by in-situ synthesis and infiltration of metal melts into WC powder compacts. Ni–W and Ni–W–Cr metal melts are in-situ synthesized from thermite reactions and infiltrated into WC powder compacts under high-gravity. During the infiltration, W in the metal melts reacts with WC to form W2C, and more W2C and W are observed at the upper parts of the cermets than the lower parts. The cermets show a maximum hardness of 15.4 GPa, which is higher than most commercial cemented carbides, although they are not fully dense and have a porosity of 15–20%.

WC1+ γδ T cells from cattle naturally infected with Mycobacterium avium subsp. paratuberculosis respond differentially to stimulation with PPD-J.

Science.gov (United States)

Albarrak, S M; Waters, W R; Stabel, J R; Hostetter, J M

2017-08-01

A role for γδ T cells in protection against mycobacterial infections including Johne's disease (JD) has been suggested. In neonatal calves where the risk to infection with Mycobacterium avium subsp. paratuberculosis (MAP) is high, the majority of circulating CD3 + lymphocytes are γδ TCR + . Bovine γδ T cells are divided into two major subsets based on the surface expression of workshop cluster 1 (WC1). The WC1 + subset, the predominant subset in periphery, is further divided into WC1.1 + and WC1.2 + subpopulations. The ability of γδ T cells to produce IFN-γ prior to CD4 + αβ T cell activation could be crucial to the outcome of MAP infection. In the current study, cattle were naturally infected with MAP and were classified as either in the subclinical or clinical stage of infection. Compared to the control non-infected group, γδ T cell frequency in circulating lymphocytes was significantly lower in the clinical group. The observed decline in frequency was restricted to the WC1.2 + subset, and was not associated with preferential migration to infection sites (distal-ileum). γδ T cells proliferated significantly in recall responses to stimulation with purified protein derivative from MAP (PPD-J) only in subclinically infected cattle. These responses were a heterogeneous mixture of WC1.1 and WC1.2 subsets. Proliferation and IFN-γ production by the WC1.1 + γδ T cell subset was significantly higher in the subclinical group compared to the control and clinical groups. Our data indicates differences in MAP-specific ex-vivo responses of peripheral WC1 + γδ T cells of cattle with the subclinical or clinical form of JD. Copyright © 2017 Elsevier B.V. All rights reserved.

Laser pulse heating of steel mixing with WC particles in a irradiated region

Science.gov (United States)

Shuja, S. Z.; Yilbas, B. S.; Ali, H.; Karatas, C.

2016-12-01

Laser pulse heating of steel mixing with tungsten carbide (WC) particles is carried out. Temperature field in the irradiated region is simulated in line with the experimental conditions. In the analysis, a laser pulse parameter is introduced, which defines the laser pulse intensity distribution at the irradiated surface. The influence of the laser parameter on the melt pool size and the maximum temperature increase in the irradiated region is examined. Surface temperature predictions are compared with the experimental data. In addition, the distribution of WC particles and their re-locations in the treated layer, due to combination of the natural convection and Marangoni currents, are predicted. The findings are compared to the experimental data. It is found that surface temperature predictions agree well with the experimental data. The dislocated WC particles form a streamlining in the near region of the melt pool wall, which agree with the experimental findings. The Gaussian distribution of the laser pulse intensity results in the maximum peak temperature and the maximum flow velocity inside the melt pool. In this case, the melt pool depth becomes the largest as compared to those corresponding to other laser pulse intensity distributions at the irradiated surface.

The Manuel Lujan Jr. Neutron Scattering Center

International Nuclear Information System (INIS)

Goldstone, J.A.

1994-01-01

High in the northcentral mountains of Los Alamos, New Mexico, is the Manuel Lujan Jr. Neutron Scattering Center (LANSCE), a pulsed-spallation neutron source located at Los Alamos National Laboratory. At LANSCE, neutrons are produced by spallation when a pulsed 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by a linear accelerator and an associated Proton Storage Ring (PSR), which alters the intensity, time structure, and repetition rate of the pulses. In October 1986, LANSCE was designated a national user facility, with a formal user program initiated in 1988. In July 1989, the LANSCE facility was dedicated as the Manuel Lujan Jr. Neutron Scattering Center in honor of the long-term Congressman from New Mexico. At present, the PSR operates with a proton pulse width of 0.27 μs at 20 Hz and 80 μA, attaining the highest peak neutron flux in the world and close to its goal of 100 μA, which would yield a peak thermal neutron flux of 10 16 n/cm -2 s -1 . This paper discusses the target/moderator/reflector shield system, the LANSCE instruments, the facility improvement projects, and user programs

The Effects of Particle Size on the Surface Properties of an HVOF Coating of WC-Co

Energy Technology Data Exchange (ETDEWEB)

Cho, Tong Yul; Yoon, Jae Hong; Yoon, Sang Hwan; Joo, Yun Kon [Changwon National University, Changwon (Korea, Republic of); Choi, Won Ho; Son, Young Bok [Xinix Metallizing Co., Ltd, Gyungnam (Korea, Republic of)

2017-04-15

The effects of particle size on the surface properties of HVOF spray coating were studied to improve of the durability of metal components. Micro and nano sized WC-12Co powders were coated on the surface of Inconel718, and the effects of particle size on surface properties were studied. Surface hardness was reduced when the particle sizes of the powder were decreased, because the larger specific surface area of the smaller particles caused greater heat absorption and decomposition of the hard WC to less hard W{sub 2}C and graphite. Porosity was increased by decreasing the particle size, because the larger specific surface area of the smaller particles caused a greater decomposition of WC to W{sub 2}C and free carbon. The free carbon formed carbon oxide gases which created the porous surface. The friction coefficient was reduced by decreasing the particle size because the larger specific surface area of the smaller particles produced more free carbon free Co and Co oxide which acted as solid lubricants. The friction coefficient increased when the surface temperature was increased from 25 to 500 ℃, due to local cold welding. To improve the durability of metal mechanical components, WC-Co coating with the proper particle size is recommended.

Study of carbide-forming element interlayers for diamond nucleation and growth on silicon and WC-Co substrates

International Nuclear Information System (INIS)

Tang, Y.; Li, Y.S.; Yang, Q.; Hirose, A.

2010-01-01

Diamond nucleation and growth on several typical carbide-forming elements (CFE) (Ti, Cr and W) coated Si and WC-Co substrates were studied. The ion beam sputtered CFE interlayers show an amorphous/nanocrystalline microstructure. The diamond formed on the CFE coated substrates shows higher nucleation density and rate and finer grain structure than on uncoated substrates. Consequently, nanocrystalline diamond thin films can be formed on the CFE coated substrates under conventional microcrystalline diamond growth conditions. Among the three tested CFE interlayers, diamond has the highest nucleation density and rate on W layer and the lowest on Ti layer. The diamond nucleation density and rate on CFE coated WC-Co are much higher than those on widely used metal nitride coated WC-Co.

Connect the Book. Martin's Big Words: The Life of Dr. Martin Luther King, Jr.

Science.gov (United States)

Brodie, Carolyn S.

2005-01-01

In honor of Martin Luther King, Jr. Day, this month's featured book is "Martin's Big Words: The Life of Dr. Martin Luther King, Jr." The book was written by Doreen Rappaport and illustrated by Bryan Collier (Jump at the Sun, 2001. 40p. ISBN 0786807148). This pictorial biography of the world-renowned civil rights leader has one of the most striking…

An Experimental Study on Slurry Erosion Resistance of Single and Multilayered Deposits of Ni-WC Produced by Laser-Based Powder Deposition Process

Science.gov (United States)

Balu, Prabu; Hamid, Syed; Kovacevic, Radovan

2013-11-01

Single and multilayered deposits containing different mass fractions of tungsten carbide (WC) in nickel (Ni)-matrix (NT-20, NT-60, NT-80) are deposited on a AISI 4140 steel substrate using a laser-based powder deposition process. The transverse cross section of the coupons reveals that the higher the mass fraction of WC in Ni-matrix leads to a more uniform distribution through Ni-matrix. The slurry erosion resistance of the fabricated coupons is tested at three different impingement angles using an abrasive water jet cutting machine, which is quantified based on the erosion rate. The top layer of a multilayered deposit (i.e., NT-60 in a two-layer NT-60 over NT-20 deposit) exhibits better erosion resistance at all three tested impingement angles when compared to a single-layer (NT-60) deposit. A definite increase in the erosion resistance is noted with an addition of nano-size WC particles. The relationship between the different mass fractions of reinforcement (WC) in the deposited composite material (Ni-WC) and their corresponding matrix (Ni) hardness on the erosion rate is studied. The eroded surface is analyzed in the light of a three-dimensional (3-D) profilometer and a scanning electron microscope (SEM). The results show that a volume fraction of approximately 62% of WC with a Ni-matrix hardness of 540 HV resulting in the gouging out of WC from the Ni-matrix by the action of slurry. It is concluded that the slurry erosion resistance of the AISI 4140 steel can be significantly enhanced by introducing single and multilayered deposits of Ni-WC composite material fabricated by the laser-based powder deposition process.

Performance characterization of Ni60-WC coating on steel processed with supersonic laser deposition

Directory of Open Access Journals (Sweden)

Fang Luo

2015-03-01

Full Text Available Ni60-WC particles are used to improve the wear resistance of hard-facing steel due to their high hardness. An emerging technology that combines laser with cold spraying to deposit the hard-facing coatings is known as supersonic laser deposition. In this study, Ni60-WC is deposited on low-carbon steel using SLD. The microstructure and performance of the coatings are investigated through SEM, optical microscopy, EDS, XRD, microhardness and pin-on-disc wear tests. The experimental results of the coating processed with the optimal parameters are compared to those of the coating deposited using laser cladding.

WC Nanocrystals Grown on Vertically Aligned Carbon Nanotubes: An Efficient and Stable Electrocatalyst for Hydrogen Evolution Reaction.

Science.gov (United States)

Fan, Xiujun; Zhou, Haiqing; Guo, Xia

2015-05-26

Single nanocrystalline tungsten carbide (WC) was first synthesized on the tips of vertically aligned carbon nanotubes (VA-CNTs) with a hot filament chemical vapor deposition (HF-CVD) method through the directly reaction of tungsten metal with carbon source. The VA-CNTs with preservation of vertical structure integrity and alignment play an important role to support the nanocrystalline WC growth. With the high crystallinity, small size, and uniform distribution of WC particles on the carbon support, the formed WC-CNTs material exhibited an excellent catalytic activity for hydrogen evolution reaction (HER), giving a η10 (the overpotential for driving a current of 10 mA cm(-2)) of 145 mV, onset potential of 15 mV, exchange current density@ 300 mV of 117.6 mV and Tafel slope values of 72 mV dec(-1) in acid solution, and η10 of 137 mV, onset potential of 16 mV, exchange current density@ 300 mV of 33.1 mV and Tafel slope values of 106 mV dec(-1) in alkaline media, respectively. Electrochemical stability test further confirms the long-term operation of the catalyst in both acidic and alkaline media.

TRUMP3-JR: a finite difference computer program for nonlinear heat conduction problems

International Nuclear Information System (INIS)

Ikushima, Takeshi

1984-02-01

Computer program TRUMP3-JR is a revised version of TRUMP3 which is a finite difference computer program used for the solution of multi-dimensional nonlinear heat conduction problems. Pre- and post-processings for input data generation and graphical representations of calculation results of TRUMP3 are avaiable in TRUMP3-JR. The calculation equations, program descriptions and user's instruction are presented. A sample problem is described to demonstrate the use of the program. (author)

Abnormal growth of faceted (WC) grains in a (Co) liquid matrix

International Nuclear Information System (INIS)

Park, Y.J.; Yoon, D.Y.

1996-01-01

If the grains dispersed in a liquid matrix are spherical, their surface atomic structure is expected to be rough (diffuse), and their coarsening has been observed to be controlled by diffusion in the matrix. They do not, furthermore, undergo abnormal growth. On the other hand, in some compound material systems, the grains in liquid matrices are faceted and often show abnormal coarsening behavior. Their faceted surface planes are expected to be singular (atomically flat) and therefore grow by a defect-assisted process and two-dimensional (2-D) nucleation. Contrary to the usual coarsening theories, their growth velocity is not linearly dependent on the driving force arising from the grain size difference. If the growth of the faceted grains occurs by 2-D nucleation, the rate is expected to increase abruptly at a critical supersaturation, as has been observed in crystal growth in melts and solutions. It is proposed that this growth mechanism leads to the abnormal grain coarsening. The 2-D nucleation theory predicts that there is a threshold initial grain size for the abnormal grain growth (AGG), and the propensity for AGG will increase with the heat-treatment temperature. The AGG behavior will also vary with the defects in the grains. These predictions are qualitatively confirmed in the sintered WC-Co alloy prepared from fine (0.85-microm) and coarse (5.48-microm) WC powders and their mixtures. The observed dependence of the AGG behavior on the sintering temperature and the milling of the WC powder is also qualitatively consistent with the predicted behavior

Finding the Right Formula: Edwin H. Walker Jr

Science.gov (United States)

Keels, Crystal L.

2005-01-01

Edwin H. Walker Jr earned his doctorate in chemistry at age 27 and has barely looked back. With 13 publications under his belt before coming out of graduate school, he has also given more than 20 poster presentations in national venues, most recently at the American Chemical Society. He can also include securing a half-million-dollar National…

J.R. SIMPLOT EX-SITU BIOREMEDIATION TECHNOLOGY FOR TREATMENT OF DINOSEB-CONTAMINATED SOILS - INNOVATIVE TECHNOLOGY REPORT

Science.gov (United States)

This report summarizes the findings of an evaluation of the J.R. Simplot Ex-Situ Bioremediation Technology on the degradation of dinoseb (2-set-butyl-4,6-dinitrophenol) an agricultural herbicide. This technology was developed by the J.R. Simplot Company (Simplot) to biologically ...

Tribological Behavior of Multilayered WC-Ti1-xAlxN Coatings Deposited by Cathodic Arc Deposition Process on High Speed Steel

International Nuclear Information System (INIS)

Kim, Jung Gu; Hwang, Woon Suk

2006-01-01

Recently, much of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel. The prepared samples are designed as WC-Ti 0.6 Al 0.4 N, WC-Ti 0.53 Al 0.47 N, WC-Ti 0.5 Al 0.5 N and WC-Ti 0.43 Al 0.57 N. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behavior. Especially, wear tests of four multilayered coatings were preformed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec, 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball (H R = 66) having a diameter of 10 mm. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Results have showed an improved wear resistance of the WC-Ti 1-x 6Al x N coatings with increasing of Al concentration. WC-Ti 0.43 Al 0.57 N coating with the lower surface roughness and porosity with good adhesion enhanced wear resistance

Corrosion of WC-VC-Co hardmetal in neutral chloride containing media

CSIR Research Space (South Africa)

Machio, Christopher N

2013-01-01

Full Text Available , “Electrochemical oxidation of WC in acidic sulphate solution,” Corrosion Science, vol. 46, no. 2, pp. 453–469, 2004. [18] T. Kubo and Y. Nishikitani, “Deposition temperature depen- dence of optical gap and coloration efficiency spectrum in elec- trochromic tungsten...

Free energies of formation of WC and WzC and the thermodynamic properties of carbon in solid tungsten

Science.gov (United States)

Gupta, D. K.; Seigle, L. L.

1974-01-01

The activity of carbon in the two-phase regions - W + WC and W + W2C was obtained from the carbon content of iron rods equilibrated with mixtures of metal plus carbide powders. From this activity data the standard free energies of formation of WC and W2C were calculated. The temperature of the invariant reaction W2C = W + WC was fixed at 1570 + or - 5K. Using available solubility data for C in solid W, the partial molar free energy of C in the dilute solid solution was also calculated. The heat of solution of C in W, and the excess entropy for the interstitial solid solution, were computed, assuming that the carbon atoms reside in the octahedral interstices of bcc W.

A study of Ni-based WC composite coatings by laser induction hybrid rapid cladding with elliptical spot

International Nuclear Information System (INIS)

Zhou Shengfeng; Huang Yongjun; Zeng Xiaoyan

2008-01-01

Ni-based WC composite coatings by laser induction hybrid rapid cladding (LIHRC) with elliptical spot were investigated. Results indicate that the efficiency using the elliptical spot of 6 mm x 4 mm (the major and minor axis of laser beam are 6 mm and 4 mm, respectively, the major axis is parallel to the direction of laser scanning) is higher than that using the elliptical spot of 4 mm x 6 mm (the major axis is perpendicular to the direction of laser scanning). The precipitated carbides with the blocky and bar-like shape indicate that WC particles suffer from the heat damage of 'the disintegration pattern + the growth pattern', whichever elliptical spot is used at low laser scanning speed. However, at high laser scanning speed, the blocky carbides are only formed if the elliptical spot of 6 mm x 4 mm is adopted, showing that WC particles present the heat damage of 'the disintegration pattern', whereas the fine carbides are precipitated when the elliptical spot of 4 mm x 6 mm is used, showing that WC particles take on the heat damage of 'the radiation pattern'. Especially, the efficiency of LIHRC is increased much four times higher than that of the general laser cladding and crack-free ceramic-metal coatings can be obtained

Properties of hard alloys on the basis of WC-Co with the additives of nanodisperse TiN

International Nuclear Information System (INIS)

Ordanyan, S.S.; Andronova, T.E.; Vladimirova, M.A.; Pantelejev, I.B.; Zalite, I.

2001-01-01

The addition of nanodisperse titanium nitride (specific surface area of 20 - 30 m 2 /g, medium diameter of grains of 50 - 100 nm) to the starting hard alloy WC-Co in the stage of wet grinding allows to get some advantages: the growth of WC grains is retarded by the nanoparticles of TiN, being as a barrier for the process of secondary crystallization, and the toughness of hard alloy is being increased due to the formation of finely dispersed structure; the exploitation characteristics of cutting instruments are increased due to the volume alloying by means of titanium nitride having a decreased adhesion to the treated metal and decreased coefficient of friction; the formation of diffusion porosity is being eliminated due to the small size of TiN during the unavoidable dissolution of WC in TiN. (author)

WC-Co coatings deposited by the electro-thermal chemical spray method

Energy Technology Data Exchange (ETDEWEB)

Zhitomirsky, V.N. [Tel Aviv Univ. (Israel). Faculty of Engineering; Wald, S.; Rabani, L.; Zoler, D. [Propulsion Physics Division, SOREQ NRC, 81800, Yavne (Israel); Factor, M.; Roman, I. [School of Applied Sciences, The Hebrew University, 91904, Jerusalem (Israel); Cuperman, S.; Bruma, C. [School of Physics and Astronomy, Tel-Aviv University, 69978, Tel-Aviv (Israel)

2000-10-02

A novel thermal spray technology - an electro-thermal chemical spray (ETCS) for producing hard coatings is presented. The experimental coating apparatus consists of a machine gun barrel, a cartridge containing the coating material in powder form, a solid propellant, and a plasma ignition system. The plasma ignition system produces plasma in pulsed mode to ignite the solid propellant. On ignition, the drag force exerted by the combustion gases accelerates the powder particles towards the substrate. Using the ETCS technique, the process of single-shot WC-Co coating deposition on stainless steel substrate was studied. The influence of process parameters (plasma energy, mass of the solid propellant and the coated powder, distance between the gun muzzle and the substrate) on the coating structure and some of its properties were investigated. It was shown that ECTS technique effectively deposited the WC-Co coating with deposition thicknesses of 100-200 {mu}m per shot, while deposition yield of {proportional_to}70% was attained. The WC-Co coatings consisted of carbide particles distributed in amorphous matrix. The powder particle velocity was found to depend on the solid propellant mass and was weakly dependent on the plasma energy, while the particle processing temperature was strongly dependent on the plasma energy and almost independent of the solid propellant mass. Whilst increasing the solid propellant mass from 5 to 7 g, the deposition rate and yield correspondingly increased. When increasing the plasma energy, the temperature of the powder particles increased, the average carbide particle size decreased and their shape became more rounded. The deposition yield and microhardness at first increased and then achieved saturation by increasing the plasma energy. (orig.)

J.R. SIMPLOT EX-SITU BIOREMEDIATION TECHNOLOGY FOR TREATMENT OF TNT-CONTAMINATED SOILS - INNOVATIVE TECHNOLOGY EVALUATION REPORT

Science.gov (United States)

This report summarizes the findings of the second evaluation of the J.R. Simplot Ex-situ Bioremediation Technology also known as the Simplot Anaerobic Bioremediation (SABRE™) process. This technology was developed by the J.R. Simplot Company to biologically degrade nitroaromatic...

Microstructure and wear resistance of laser cladded composite coatings prepared from pre-alloyed WC-NiCrMo powder with different laser spots

Science.gov (United States)

Yao, Jianhua; Zhang, Jie; Wu, Guolong; Wang, Liang; Zhang, Qunli; Liu, Rong

2018-05-01

The distribution of WC particles in laser cladded composite coatings can significantly affect the wear resistance of the coatings under aggressive environments. In this study, pre-alloyed WC-NiCrMo powder is deposited on SS316L via laser cladding with circular spot and wide-band spot, respectively. The microstructure and WC distribution of the coatings are investigated with optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The wear behavior of the coatings is investigated under dry sliding-wear test. The experimental results show that the partially dissolved WC particles are uniformly distributed in both coatings produced with circular spot and wide-band spot, respectively, and the microstructures consist of WC and M23C6 carbides and γ-(Ni, Fe) solid solution matrix. However, due to Fe dilution, the two coatings have different microstructural characteristics, resulting in different hardness and wear resistance. The wide-band spot laser prepared coating shows better performance than the circular spot laser prepared coating.

Action memorandum for the Waste Area Grouping 1 Tank WC-14 removal action at Oak Ridge National Laboratory, Oak Ridge, Tennessee

International Nuclear Information System (INIS)

1994-11-01

This action memorandum documents approval for a Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended (CERCLA), time-critical action. The action will remove radiologically contaminated water from Tank WC-14. The water contains a polychlorinated biphenyl (PCB) at a level below regulatory concern. Tank WC-14 is located in the Waste Area Grouping (WAG) 1 WC-10 Tank Farm at the Oak Ridge National Laboratory (ORNL), Oak Ridge, Tennessee. Contaminated sludge remaining in the tank after removal of the liquid will be the subject of a future action

Role of WC additive on reaction, solid-solution and densification in HfB2–SiC ceramics

DEFF Research Database (Denmark)

Hu, Dong-Li; Zheng, Qiang; Gu, Hui

2014-01-01

A comparative study of phase components and compositions was performed for the pressureless sintered HfB2–SiC–WC composites by various analytical methods. The relative decrease of HfB2 phase leads to a new reaction of HfO2 removal by WC to create B2O3. By using SiC instead of Si3N4 as milling med...

SiC interlayer by laser-cladding on WC-Co substrates for CVD diamond deposition

Energy Technology Data Exchange (ETDEWEB)

Contin, Andre; Fraga, Mariana Amorim; Vieira, Jose; Trava-Airoldi, Vladimir Jesus; Corat, Evaldo Jose, E-mail: andrecontin@yahoo.com.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil); Campos, Raonei Alves [Universidade Federal do Sul e Sudeste do Para (UNIFESSPA), Belem, PA (Brazil); Vasconcelos, Getulio [Instituto de Estudos Avancados (IEA), Sao Jose dos Campos, SP (Brazil)

2016-07-01

Full text: Despite their huge industrial potential and commercial interest, the direct diamond coating on cemented carbide (WC-Co) is limited, mainly because of the catalytic effect of Cobalt (Co) and the high difference in thermal expansion coefficient [1]. This results in poor adherence between diamond and WC-Co. In addition, the low diamond film adhesion to the cemented carbide useless for machining applications. Removal of Co binder from the substrate surface by superficial etching is one of the techniques used to improve the adhesion between diamond and WC-Co. For the present study, diamond films were deposited on WC-Co substrates with an intermediate barrier to block the Co diffusion to the surface substrate. The laser cladding process produced the SiC barrier, in which a powder layer is melted by a laser irradiation to create the coating on the substrate. The use of laser cladding is the novel method for an intermediate barrier for cemented carbides. The advantages of laser cladding include a faster processing speed, precision, versatility. We reported the application of pretreatment method called ESND (Electrostatic self-assembly seeding of nanocrystalline diamond). The nucleation density was around 10{sup 11}part/cm{sup 2}. Diamond films were grown by Hot Filament Chemical Vapor Deposition. Characterization of samples included Field Emission Gun-Scanning Electron Microscopy (FEG-SEM), Energy Dispersive X-ray (EDX), X-ray diffraction (XRD) and Raman Scattering Spectroscopy. Results showed that laser irradiation formed stable Co compounds in the interfacial barrier. It is because nucleation and good quality of diamond film since the cobalt are no longer free to migrate to the surface during the CVD diamond deposition. Reference: [1] Y. X. Cui, B. Shen, F. H. Sun. Diamond deposition on WC–Co substrate with amorphous SiC interlayer, Surface Engineering, 30, (2014) 237-243. (author)

Effects of NbC additions on the microstructure and properties of non-uniform structure WC-Co cemented carbides

Energy Technology Data Exchange (ETDEWEB)

Gao, Yang; Yan, Ming-Yuan, E-mail: 704878879@qq.com; Luo, Bing-Hui, E-mail: luobinghui@csu.edu.cn; Ouyang, Sheng; Chen, Wei; Bai, Zhen-hai; Jing, Hui-bo; Zhang, Wen-Wen

2017-02-27

In this work, the effects of NbC additions on microstructure and properties of non-uniform structure WC-7Co cemented carbides were investigated X-ray diffractometer, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), mechanical properties tester and electrochemical workstation, respectively. The results show that WC phase can be partially dissolved into the NbC to form a (Nb,W)C solid solution. According to EPMA analysis, the amount of W atoms, dissolving into the NbC grains, increases with the NbC addition. Moreover, when the content of NbC is beyond 1%, the WC-Co cemented carbides with non-uniform structure are formed with significant reduction of average grain size of WC. With NbC addition increasing from 0 wt% to 2 wt%, the hardness is increased from 1475 MPa to 1570 MPa while the fracture toughness decreased from 12.1 MPa m{sup 1/2} to 10.3 MPa m{sup 1/2}. However, with the further addition of NbC, the hardness slightly decreased. With NbC addition between 0 and 1 wt%, the TRS is gradually decreased from 2982 MPa to 2745 MPa, while, as the NbC content exceeds 1 wt%, the TRS leveled off. Because of the decrease of grain size and the (Nb,W)C phase formation, caused by NbC addition, the crack defection was weakened, which led to the decrease of fracture toughness. Meanwhile, the corrosion resistance of non-uniform structure WC-Co cemented carbides can be significantly improved by adding NbC to the material due to increased α-Co in binder phase.

FIB-SEM Sectioning Study of Decarburization Products in the Microstructure of HVOF-Sprayed WC-Co Coatings

Science.gov (United States)

Katranidis, Vasileios; Gu, Sai; Cox, David C.; Whiting, Mark J.; Kamnis, Spyros

2018-05-01

The thermal dissolution and decarburization of WC-based powders that occur in various spray processes are a widely studied phenomenon, and mechanisms that describe its development have been proposed. However, the exact formation mechanism of decarburization products such as metallic W is not yet established. A WC-17Co coating is sprayed intentionally at an exceedingly long spray distance to exaggerate the decarburization effects. Progressive xenon plasma ion milling of the examined surface has revealed microstructural features that would have been smeared away by conventional polishing. Serial sectioning provided insights on the three-dimensional structure of the decarburization products. Metallic W has been found to form a shell around small splats that did not deform significantly upon impact, suggesting that its crystallization occurs during the in-flight stage of the particles. W2C crystals are more prominent on WC faces that are in close proximity with splat boundaries indicating an accelerated decarburization in such sites. Porosity can be clearly categorized in imperfect intersplat contact and oxidation-generated gases via its shape.

Composite coating containing WC/12Co cermet and Fe-based metallic glass deposited by high-velocity oxygen fuel spraying

International Nuclear Information System (INIS)

Terajima, Takeshi; Takeuchi, Fumiya; Nakata, Kazuhiro; Adachi, Shinichiro; Nakashima, Koji; Igarashi, Takanori

2010-01-01

A composite coating containing WC/12Co cermet and Fe 43 Cr 16 Mo 16 C 15 B 10 metallic glass was successfully deposited onto type 304 stainless steel by high-velocity oxygen fuel (HVOF) spraying, and the microstructure and tribological properties were investigated. The microstructure of the coating was characterized by scanning electron microscopy/electron probe micro-analysis (SEM/EPMA) and X-ray diffractometry (XRD). The hardness, adhesion strength and tribological properties of the coating were tested with a Vickers hardness tester, tensile tester and reciprocating wear tester, respectively. The composite coating, in which flattened WC/12Co was embedded in amorphous Fe 43 Cr 16 Mo 16 C 15 B 10 layers, exhibited high hardness, good wear resistance and a low friction coefficient compared to the monolithic coating. The addition of 8% WC/12Co to the Fe 43 Cr 16 Mo 16 C 15 B 10 matrix increased the cross-sectional hardness from 660 to 870 HV and reduced the friction coefficient from 0.65 to 0.5. WC/12Co reinforcement plays an important role in improving the tribological properties of the Fe 43 Cr 16 Mo 16 C 15 B 10 coating.

Morpho-Structural Characterization of WC20Co Deposited Layers

Science.gov (United States)

Tugui, C. A.; Vizureanu, P.

2017-06-01

Hydroelectric power plants use the power of water to produce electricity. In this paper we propose a solution that will increase the efficiency of turbine operation by implementing new innovative technologies to increase the working characteristics by depositing hard thin films of tungsten carbide. For this purpose hard tough deposits with WC20Co and Jet Plasma Jet on X3CrNiMo13-4 stainless steel were used for the realization of the Francis turbine with vertical shaft.

Ultra-short-period WC/SiC multilayer coatings for x-ray applications

DEFF Research Database (Denmark)

Fernandez-Perea, M.; Pivovaroff, M. J.; Soufli, R.

2013-01-01

developed multilayers with ultra-shortperiods between 1 and 2 nm based on the material system WC/SiC. This material system was selected because it possesses very sharp and stable interfaces. In this article, we show highlights from a series of experiments performed in order to characterize the stress...

Dynamic J-R Characteristics of RCS Pipe Materials for Ulchin Unit 3/4. (Evaluation of Dynamic Strain Aging Effects)

Energy Technology Data Exchange (ETDEWEB)

Hong, Jun Hwa; Lee, Bong Sang; Yoon, Ji Hyun; Oh, Jong Myung; Kim, Jin Won [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-09-01

5 materials (45 1T-CT specimens) were tested to evaluate dynamic J-R characteristics of RCS Pipe Materials for Ulchin Unit 3/4 (Evaluation of Dynamic Strain Aging Effects). The tests were performed by DCPD method at 316 deg C and 25 deg C. The loading rates were 1000mm/min and 2000mm/min. The objectives of this project were to obtain the dynamic J-R curves data of ferritic steels for application of LBB to the RCS pipes of Ulchin Unit 3/4. The test results showed that all of the tested dynamic J-R curves of 5 materials were above the lower bound curve of static J-R curve of pipe materials for Ulchin Unit 3/4. 10 refs., 4 tabs., 16 figs. (author)

Effect of helium plasma gas flow rate on the properties of WC-12 wt.%Co coatings sprayed by atmospheric plasma

Directory of Open Access Journals (Sweden)

Mihailo R. Mrdak

2014-06-01

Full Text Available The cermet coatings of WC-12wt.%Co are extensively used to improve the wear resistance of a wide range of technical components. This paper analyses the influence of the plasma gas flow of helium on the microstructure and mechanical properties of WC-12wt.%Co coatings deposited by plasma spraying at atmospheric pressure (APS. In order to obtain homogeneous and denser coatings, three different flows of He ( 8 l/min., 16 l/min. and 32 l/min were used in the research. With the application of He, coatings achieved higher values of hardness due to less degradation of the primary WC carbides. The main goal was to deposit dense and homogeneous layers of WC-12wt.%Co coatings with improved wear resistance for different applications. The test results of the microstructure of the layers were evaluated under a light microscope. The analysis of the microstructure and the mechanical properties of the deposited layers was made in accordance with the standard of Pratt-Whitney. The morphology of the powder particles and the microstructure of the best coating was examined on the SEM (scanning electron microscope. The evaluation of the mechanical properties of the layers was done by applying the HV0.3 method for microhardness testing and by applying tensile testing to test the bond strength. The research has shown that the flow of He plasma gas significantly affects the microstructure, the mechanical properties and the structure of WC-12 wt.%Co coatings.

Data of evolutionary structure change: 1A9WC-2ZLWD [Confc[Archive

Lifescience Database Archive (English)

Full Text Available 1A9WC-2ZLWD 1A9W 2ZLW C D -VLSPADKTNVKAAWGKVGAHAGEYGAEALERMFLSFPT...R VQLSGEEKAAVLALWDKVN--EEEVGGEALGRLLVVYPWTQRFFDSFGDLSNPGAVMGNPKVKAHGKKVLHSFGEGVHHLDNLKGTFAALSEL...onfEVID> 1 2ZLW D 2ZLWD... CA 264 LYS CA 243 2ZLW D 2ZLWD DLSNPGAVMGNPKVK HHHH

75 FR 3839 - Martin Luther King, Jr., Federal Holiday, 2010

Science.gov (United States)

2010-01-22

... Part III The President Proclamation 8473--Martin Luther King, Jr., Federal Holiday, 2010 Proclamation 8474--Religious Freedom Day, 2010 Notice of January 20, 2010--Continuation of the National... only by the power of his words, which still call on us to perfect those sacred ideals enshrined in our...

Aegla rosanae Campos Jr., um novo sinônimo de Aegla paulensis Schmitt (Crustacea, Aeglidae Aegla rosanae Campos Jr., a new synonym of Aegla paulensis Schmitt (Crustacea, Aeglidae

Directory of Open Access Journals (Sweden)

Georgina Bond-Buckup

2000-06-01

Full Text Available The validity of Aegla rosanae Campos Jr., 1998 as a new species was analysed. On the basis of comparisons with Aegla paulensis Schmitt, A. rosanae was considered its junior synonym.

On the sintering behaviour of steel bonded TiC-Cr3C2 and TiC-Cr3C2-WC mixed carbides

International Nuclear Information System (INIS)

Stojanov, L.G.; Exner, H.E.

1978-01-01

Powder mixtures of TiC+Cr 3 C 2 and TiC+Cr 3 C 2 + WC were hot pressed to nearly full density. The lattice parameter of the resulting cubic mixed crystal decreases linearly with increasing additions of Cr 3 C 2 and (Cr 3 C 2 +WC 1:1). Microhardness increases with Cr 3 C 2 content up to 20 wt.%. By addition of WC, microhardness is increased further and reaches a maximum value of approx. 38 000 MN/m 2 for 20 wt.% Cr 3 C 2 and 20 wt.% WC. From these solid solutions powder compositions of Ferro-TiC type were produced by milling with 55 wt.% Fe and 0.4 wt.% C. The sintering behaviour of these powders was studied in a vacuum dilatometer. The pronounced increase of shrinkage by Cr 3 C 2 and higher amounts of Cr 3 C 2 +WC dissolved in TiC previous to binder phase melting is attributed to the increased solubility of the carbide in solid iron. Presintering at 700 0 C in hydrogen has a negative influence on sintering activity and requires much higher temperatures for complete densification during subsequent vacuum sintering. (orig.) [de

Evaluation of J-R curve testing of nuclear piping materials using the direct current potential drop technique

International Nuclear Information System (INIS)

Hackett, E.M.; Kirk, M.T.; Hays, R.A.

1986-08-01

A method is described for developing J-R curves for nuclear piping materials using the DC Potential Drop (DCPD) technique. Experimental calibration curves were developed for both three point bend and compact specimen geometries using ASTM A106 steel, a type 304 stainless steel and a high strength aluminum alloy. These curves were fit with a power law expression over the range of crack extension encountered during J-R curve tests (0.6 a/W to 0.8 a/W). The calibration curves were insensitive to both material and sidegrooving and depended solely on specimen geometry and lead attachment points. Crack initiation in J-R curve tests using DCPD was determined by a deviation from a linear region on a plot of COD vs. DCPD. The validity of this criterion for ASTM A106 steel was determined by a series of multispecimen tests that bracketed the initiation region. A statistical differential slope procedure for determination of the crack initiation point is presented and discussed. J-R curve tests were performed on ASTM A106 steel and type 304 stainless steel using both the elastic compliance and DCPD techniques to assess R-curve comparability. J-R curves determined using the two approaches were found to be in good agreement for ASTM A106 steel. The applicability of the DCPD technique to type 304 stainless steel and high rate loading of ferromagnetic materials is discussed. 15 refs., 33 figs

Herbert L. Pick Jr. (1930-2012).

Science.gov (United States)

Rieser, John J; Lockman, Jeffrey J

2013-01-01

Presents an obituary for Herbert L. Pick Jr. For 49 years at the University of Minnesota's Institute of Child Development, new students were often greeted by an unassuming guy who rode to work on his bike, helped them carry boxes of books to their offices, and turned out to be a famous professor. Herbert L. Pick Jr. was a fabulous mentor, teacher, and developmental scientist. His work on perception and perceptual development spanned basic and applied science, laboratory and real-world settings. He was honored with the Division 7 (Developmental Psychology) Mentor Award from the American Psychological Association in 1998. He was honored again in 2002, jointly with his wife Anne D. Pick, with a volume of the Minnesota Symposium on Child Psychology based on a central theme of their work and titled "Action as an Organizer of Learning and Development." Two weeks before his death he was honored yet again with a Festschrift titled "Realism to Relevance: An Ecological Approach to Perception, Action and Cognition." Former students and academic admirers gave talks focused on the scientific themes Herb championed, namely, effects of experience on learning and development, organism-environment fit, environmental structure, and societal applications of research about basic psychological processes. He gave the final talk, and after thanking everyone in his typically humble way, he discussed his new research on visual-locomotor coordination. Herb died on June 18, 2012. He is greatly missed by Anne, his wife of 50 years; his sister Barbara; his daughters (and their husbands) Cindy (Jon), Karen (John), and Gretchen (Michael); and his grandchildren Alex, Ted, Katy, Joe, Eva, Sam, Rowan, and Culley. He is also missed by his many students, colleagues, friends, and admirers.

Direct fabrication of a W-C SNS Josephson junction using focused-ion-beam chemical vapour deposition

International Nuclear Information System (INIS)

Dai, Jun; Kometani, Reo; Ishihara, Sunao; Warisawa, Shin’ichi; Onomitsu, Koji; Krockenberger, Yoshiharu; Yamaguchi, Hiroshi

2014-01-01

A tungsten-carbide (W-C) superconductor/normal metal/superconductor (SNS) Josephson junction has been fabricated using focused-ion-beam chemical vapour deposition (FIB-CVD). Under certain process conditions, the component ratio has been tuned from W: C: Ga = 26%: 66%: 8% in the superconducting wires to W: C: Ga = 14%: 79%: 7% in the metallic junction. The critical current density at 2.5 K in the SNS Josephson junction is 1/3 of that in W-C superconducting nanowire. Also, a Fraunhofer-like oscillation of critical current in the junction with four periods is observed. FIB-CVD opens avenues for novel functional superconducting nanodevices. (paper)

Performances and reliability of WC based thermal spray coatings

International Nuclear Information System (INIS)

Scrivani, A.; Rosso, M.; Salvarani, L.

2001-01-01

Thermal spray processes are used for a lot of traditional and innovative applications and their importance is becoming higher and higher. WC/CoCr based thermal spray coatings represent one of the most important class of coatings that find application in a wide range of industrial sectors. This paper will address a review of current applications and characteristics of this kind of coating. The most important spraying processes, namely HVOF (high velocity oxygen fuel) are examined, the characterization of the coatings from the point of view of corrosion and wear resistance is considered. (author)

TEM INVESTIGATIONS OF WC-Co ALLOYS AFTER CREEP EXPERIMENTS

OpenAIRE

Lay , S.; Osterstock , F.; Vicens , J.

1986-01-01

Carbide tungsten cobalt alloys were deformed in compression or in three point bending in a temperature range 1000-1350°C and in a stress domain 30-1000MPa. In these conditions, the stress exponent n of WC-Co alloys is a function of only the cobalt volumic ratio and tends towards n = 1 for pure carbide. The apparent activation energy is 550 kj mole-1. T.E.M. investigations on pure carbide deformed at 1450°C show an extensive intragranular deformation. Analysis of these defects have been perfor...

The application of DCPD method to evaluating dynamic J-R fracture resistance characteristics

International Nuclear Information System (INIS)

Yoon, Ji Hyun; Hong, Jun Hwa; Lee, Bong Sang; Chi, Se Whan; Kim, Joo Hag; Oh, Yong Jun; Kwun, Sun Chil; Oh, Jong Myung

1999-06-01

The reliable DCPD (Direct Current Potential Drop) test and data acquisition system were developed on the basis of analysis of various technical problems to accompanied with the application of DCPD method to J-R fracture resistance test. The test system contains electric insulation rod and high performance data acquisition system. The test and analysis method was applied to J-R fracture resistance test for SA516-Gr.70 steel for nuclear primary coolant system elbow. The reliabilities of test and analysis method were confirmed through the load-ratio method in case of dynamic loading test, and through the standard unloading compliance test in case of static loading test. (author). 17 refs., 1 tab., 18 figs

The application of DCPD method to evaluating dynamic J-R fracture resistance characteristics

Energy Technology Data Exchange (ETDEWEB)

Yoon, Ji Hyun; Hong, Jun Hwa; Lee, Bong Sang; Chi, Se Whan; Kim, Joo Hag; Oh, Yong Jun; Kwun, Sun Chil; Oh, Jong Myung

1999-06-01

The reliable DCPD (Direct Current Potential Drop) test and data acquisition system were developed on the basis of analysis of various technical problems to accompanied with the application of DCPD method to J-R fracture resistance test. The test system contains electric insulation rod and high performance data acquisition system. The test and analysis method was applied to J-R fracture resistance test for SA516-Gr.70 steel for nuclear primary coolant system elbow. The reliabilities of test and analysis method were confirmed through the load-ratio method in case of dynamic loading test,and through the standard unloading compliance test in case of static loading test. (author). 17 refs., 1 tab., 18 figs.

Improvement of Surface Properties of Inconel718 by HVOF Coating with WC-Metal Powder and by Laser Heat Treatment of the Coating

Directory of Open Access Journals (Sweden)

Hui Gon Chun

2015-01-01

Full Text Available High-velocity oxygen-fuel (HVOF thermal spray coating with WC-metal powder was carried out by using optimal coating process on an Inconel718 surface for improvement of the surface properties, friction, wear, and corrosion resistance. Binder metals such as Cr and Ni were completely melted and WC was decomposed partially to W2C and graphite during the high temperature (up to 3500°C thermal spraying. The melted metals were bonded with WC and other carbides and were formed as WC-metal coating. The graphite and excessively sprayed oxygen formed carbon oxide gases, and these gases formed porous coating by evolution of the gases. The surface properties were improved by HVOF coating and were improved further by CO2 laser heat treatment (LH. Wear resistance of In718 surface was improved by coating and LH at 25°C and an elevated temperature of 450°C, resulting in reduction of wear trace traces, and was further improved by LH of the coating in reducing wear depth. Corrosion resistance due to coating in sea water was improved by LH. HVOF coating of WC-metal powder on a metal surface and a LH of the coating were highly recommended for the improvement of In718 surface properties, the friction behavior, and wear resistance.

MILLS B. LANE, JR. AND ENTERPRISE IN A NEW SOUTH

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Randall L. Patton

2009-01-01

Full Text Available For a century, Citizens & Southern Bank was a fixture in Georgia. In 1991, the C&S brand name disappeared in a merger with North Carolina National Bank. This was one of the bittersweet consequences of the slow, confusing swirl of bank deregulation after 1970, when institutions such as C&S simply disappeared, swallowed by the “winners” in the new competitive environment of interstate banking in the 1980s and 1990s. Even earlier, however, the Lane family had ceased to control the bank started by Mills Lane, Sr. in 1891. Mills B. Lane, Jr. was the last member of the Lane family to run C&S. After his retirement in 1973, Mills handpicked his successor and tried to retain some influence, but the bank began slipping away from the Lanes. By the early 80s, a decade before Hugh McColl’s NCNB acquired C&S, Mills Lane, Jr. was deeply alienated from the institution that had been, according to many, “Georgia’s cornerstone bank.”

Structural analysis of sputtered (W-C)1-xMx (M≡Fe,Co) films with 0≤x≤0.20

International Nuclear Information System (INIS)

Cavaleiro, A.; Trindade, B.; Vieira, M.T.

1993-01-01

Structural characterization of (W-C) 1-x M x (M≡Fe,Co) films with 0≤x≤0.20 was carried out using electron probe microanalysis (EPMA), X-ray diffraction (XRD) and transmission electron microscopy-electron diffraction (TEM-ED). The results showed that the structure of these films depends on the percentage of iron and cobalt and becomes amorphous with increasing content of these elements. The microstructure of the crystalline coatings was found to be composed of small grains of β-WC 1-x with a high number of defects. A strong β-WC 1-x [311] texture was observed for iron and cobalt contents around 5.5 at.%. The films richer in iron and cobalt showed typical amorphous XRD and ED patterns, exhibiting two broad peaks and two wide diffuse rings respectively. Moreover, bright-field analysis revealed fairly contrasted images, the structure of these films being difficult to resolve. (orig.)

Writing, Teaching, and Researching: An Interview with Rene Saldana, Jr.

Science.gov (United States)

Saldana, Rene, Jr.; Moore, David W.

2010-01-01

Rene Saldana, Jr., an assistant professor at Texas Tech University, is a writer of short stories, poetry, and novels. In order to get his storytelling right, he has relied on his memory when writing memoirs and consulted popular culture and family when writing fiction. In order to get his university teaching right, he reads seminal texts on…

DURABILITY AND TRIBOLOGICAL PROPERTIES OF THERMALLY SPRAYED WC CERMET COATING IN LUBRICATED ROLLING WITH SLIDING CONTACT

Directory of Open Access Journals (Sweden)

Mohammad Ali

2010-09-01

Full Text Available Durability and tribological properties of thermally sprayed WC-Cr-Ni cermet coating were investigated experimentally in lubricated rolling with sliding contact conditions. By means of the high energy type flame spraying (Hi-HVOF method, the coating was formed onto the axially ground and circumferentially ground roller specimens made of a thermally refined carbon steel. In the experiments, the WC cermet coated steel roller was mated with the carburized hardened steel roller without coating in line contact condition. The coated roller was mated with the smooth non-coated roller under a contact pressure of 1.0 or 1.2 GPa, and it was mated with the rough non-coated roller under a contact pressure of 0.6 or 0.8 GPa. As a result, it was found that in general, the coating on the circumferentially ground substrate shows a lower durability compared with that on the axially ground substrate and this difference appears more distinctly for the higher contact pressure for both smooth mating surface and rough mating surface. It was also found that there are significant differences in the tribological properties of WC cermet coating depending on the contact pressure. In addition, depending on the smooth or rough mating surface, remarkable differences in the tribological properties were found.

Reduction of travellers' diarrhoea by WC/rBS oral cholera vaccine in young, high-risk travellers.

Science.gov (United States)

Torrell, Josep Ma Ramon; Aumatell, Cristina Masuet; Ramos, Sergi Morchon; Mestre, Laura Gavaldà; Salas, Carme Micheo

2009-06-19

A bidirectional cohort study investigates whether pre-travel vaccination with whole cell/recombinant B subunit inactivated, killed oral cholera vaccine reduces the incidence of diarrhoea in young adult travellers to high-risk areas. Risk of travellers' diarrhoea was assessed according to destination and reason for travel in high-risk travellers of a travel clinic in Barcelona, Spain. Those at high-risk between January and December 2005 were advised on water/food safety and hygiene. High-risk travellers between January and December 2006 were additionally vaccinated with WC/rBS oral cholera vaccine. Data regarding diarrhoea were gathered by structured telephone interview or e-mailed questionnaire following the travellers' return. The incidence of diarrhoea in the group vaccinated with WC/rBS oral cholera vaccine (n=321) was 17.4%, compared with 39.7% in the non-vaccinated group (n=337) (adjusted risk ratio 0.40). The first episode was significantly shorter in the vaccinated group (mean 2.3 days) than in the non-vaccinated group (mean 3.8 days) (pyoung, high-risk travellers. Vaccination with the WC/rBS oral cholera vaccine as well as food safety and hygiene advice could offer effective means of reducing the risk of diarrhoea while abroad.

Experimental investigation of surface quality in ultrasonic machining of WC-Co composites through Taguchi method

Directory of Open Access Journals (Sweden)

B. S. Pabla

2016-08-01

Full Text Available In manufacturing industries, the demand of WC-Co composite is flourishing because of the distinctive characteristics it offers such as: toughness (with hardness, good dimensional stability, higher mechanical strength etc. However, the difficulties in its machining restrict the application and competitiveness of this material. The current article has been targeted at evaluation of the effect of process conditions (varying power rating, cobalt content, tool material, part thickness, tool geometry, and size of abrasive particle on surface roughness in ultrasonic drilling of WC-Co composite. Results showed that abrasive grit size is most influential factor. From the microstructure analysis, the mode of material deformation has been observed and the parameters, i.e. work material properties, grit size, and power rating was revealed as the most crucial for the deformation mode.

WC as a non-platinum hydrogen evolution electrocatalyst for high temperature PEM water electrolysers

DEFF Research Database (Denmark)

Nikiforov, Aleksey; Petrushina, Irina; Christensen, Erik

2012-01-01

Tungsten carbide (WC) nanopowder was tested as a non-platinum cathode electrocatalyst for polymer electrolyte membrane (PEM) water electrolysers, operating at elevated temperatures. It was prepared in thermal plasma reactor with confined plasma jet from WO3 precursor in combination with CH4...

William Knocke receives 2008 Virginia Outstanding Civil Engineer Award

OpenAIRE

Daniilidi, Christina

2008-01-01

William R. Knocke, W.C. English Professor and head of the Charles E. Via, Jr. Department of Civil and Environmental Engineering at Virginia Tech, was awarded the 2008 Virginia Outstanding Civil Engineer Award at the Virginia Section of the American Society of Civil Engineers' (ASCE) banquet, held recently in Williamsburg, Va.

Slurry Erosion Behavior of F6NM Stainless Steel and High-Velocity Oxygen Fuel-Sprayed WC-10Co-4Cr Coating

Science.gov (United States)

Cui, S. Y.; Miao, Q.; Liang, W. P.; Huang, B. Z.; Ding, Z.; Chen, B. W.

2017-02-01

WC-10Co-4Cr coating was applied to the surface of F6NM stainless steel by high-velocity oxygen-fuel spraying. The slurry erosion behavior of the matrix and coating was examined at different rotational speeds using a self-made machine. This experiment effectively simulates real slurry erosion in an environment with high silt load. At low velocity (<6 m/s), the main failure mechanism was cavitation. Small bubbles acted as an air cushion, obstructing direct contact between sand and the matrix surface. However, at velocity above 9 m/s, abrasive wear was the dominant failure mechanism. The results indicate that WC-10Co-4Cr coating significantly improved the slurry resistance at higher velocity, because it created a thin and dense WC coating on the surface.

Effects of solidified microstructures on J-R fracture resistances of the surge line pipe welds

International Nuclear Information System (INIS)

Youn, J. H.; Lee, B. S.; Yoo, W.

2003-01-01

The cause of the difference in J-R fracture resistances of AISI Type 347 GTAW welds which had almost same amounts of chromium carbides were investigated by the microstructural observations. As a result, the difference in the fracture resistances with the morphologies of the retained δ-ferrites in Type 347 welds were observed. The fracture resistance of the weld which had mostly vermicular type δ-ferrites was inferior to the weld which has lacy and acicular mixed type δ-ferrites. Therefore, it was deduced that the morphology of δ-ferrites affected the J-R fracture resistances of Type 347 welds

Effect of W/C Ratio on Durability and Porosity in Cement Mortar with Constant Cement Amount

Directory of Open Access Journals (Sweden)

Yun-Yong Kim

2014-01-01

Full Text Available Water is often added to concrete placing for easy workability and finishability in construction site. The additional mixing water can help easy mixing and workability but causes increased porosity, which yields degradation of durability and structural performances. In this paper, cement mortar samples with 0.45 of W/C (water to cement ratio are prepared for control case and durability performances are evaluated with additional water from 0.45 to 0.60 of W/C. Several durability tests including strength, chloride diffusion, air permeability, saturation, and moisture diffusion are performed, and they are analyzed with changed porosity. The changing ratios and patterns of durability performance are evaluated considering pore size distribution, total porosity, and additional water content.

Mounting a Curricular Revolution: An Interview with Henry Louis Gates, Jr.

Science.gov (United States)

von Zastrow, Claus

2009-01-01

This article presents an interview with Henry Louis Gates, Jr., Harvard professor and cultural critic who has captured 25 million viewers with his PBS documentary series, African American Lives (WNET). Using genealogical research and DNA science, Gates traces the family history of 19 famous African Americans. What results is a rich and moving…

Constructing the ScratchJr Programming Language in the Early Childhood Classroom

Science.gov (United States)

Portelance, Dylan J.; Strawhacker, Amanda L.; Bers, Marina Umaschi

2016-01-01

This paper seeks to contribute to the growing literature on children and computer programming by focusing on a programming language for children in Kindergarten through second grade. Sixty-two students were exposed to a 6-week curriculum using ScartchJr. They learned foundational programming concepts and applied those concepts to create personally…

Effect of SiC Nanowhisker on the Microstructure and Mechanical Properties of WC-Ni Cemented Carbide Prepared by Spark Plasma Sintering

Directory of Open Access Journals (Sweden)

Xiaoyong Ren

2014-01-01

Full Text Available Ultrafine tungsten carbide-nickel (WC-Ni cemented carbides with varied fractions of silicon carbide (SiC nanowhisker (0–3.75 wt.% were fabricated by spark plasma sintering at 1350°C under a uniaxial pressure of 50 MPa with the assistance of vanadium carbide (VC and tantalum carbide (TaC as WC grain growth inhibitors. The effects of SiC nanowhisker on the microstructure and mechanical properties of the as-prepared WC-Ni cemented carbides were investigated. X-ray diffraction analysis revealed that during spark plasma sintering (SPS Ni may react with the applied SiC nanowhisker, forming Ni2Si and graphite. Scanning electron microscopy examination indicated that, with the addition of SiC nanowhisker, the average WC grain size decreased from 400 to 350 nm. However, with the additional fractions of SiC nanowhisker, more and more Si-rich aggregates appeared. With the increase in the added fraction of SiC nanowhisker, the Vickers hardness of the samples initially increased and then decreased, reaching its maximum of about 24.9 GPa when 0.75 wt.% SiC nanowhisker was added. However, the flexural strength of the sample gradually decreased with increasing addition fraction of SiC nanowhisker.

Coating Properties of WC-Ni Cold Spray Coating for the Application in Secondary Piping System of Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Kim, JeongWon; Kim, Seunghyun; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

2015-10-15

As a result of FAC(flow accelerated corrosion), severe accidents, failure of carbon steel like a Mihama Unit-3 occurred. Chemical composition change of carbon steel or coating to inner surface is one of methods to improve corrosion properties. Among them, thermal spray coating is convenient solution to apply at industry. Powder is melted at blast furnace and ejected to substrate. After adhesion, substrate and coating layer is cooled down and coated layer protects steel from corrosion finally. However high thermal energy is transferred to substrate and coating layer so it leads high thermal residual stress in coating procedure. Besides, high temperature for melting powder makes unexpected chemical reaction of powder like an oxidation or carburization. Whereas, cold spray uses low temperature comparing with other thermal spray. Thermal energy is used for not melting powder but high kinetic energy of powder and plastic deformation during collision. Therefore, fuel such as oxygen-acetylene gas is not needed. It needs carrier gas, compressed air, nitrogen or helium, to increase kinetic energy of powder and move powder to substrate. Comparing cold spray with high velocity oxy fuel (HVOF), one of thermal spray, cold spray coating layer contains only WC and Co. One of other problem about WC is brittleness during coating. To improve deformability of WC, binder metal is added. For example, Co, Cr, Ni, Cu, Al, Fe or etc. Additionally, binder metal lowering melting temperature of composite powder increases coating properties. Among them, Co which is widely used as binder metal maintains mechanical properties like a hardness and improves corrosion properties. Therefore Co is not suitable for binder metal of WC coating. In contrast, Ni has better corrosion resistance to alkaline environment and makes lower melting temperature. Moreover, in a view of cold spray, FCC structure has better deformability than BCC or HCP, and BCC has lowest deformability. WC is BCC structure so it

Effect of Mo2C/(Mo2C + WC) weight ratio on the microstructure and mechanical properties of Ti(C,N)-based cermet tool materials

International Nuclear Information System (INIS)

Xu, Qingzhong; Zhao, Jun; Ai, Xing; Qin, Wenzhen; Wang, Dawei; Huang, Weimin

2015-01-01

To optimize the Mo 2 C content in Ti(C,N)-based cermet tool materials used for cutting the high-strength steel of 42CrMo (AISI 4140/4142 steel), the cermets with different Mo 2 C/(Mo 2 C + WC) weight ratios were prepared. And the microstructure and mechanical properties of cermets were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and measurements of transverse rupture strength (TRS), Vickers hardness (HV) and fracture toughness (K IC ). The results indicate that the Mo 2 C/(Mo 2 C + WC) ratios have great influences on the microstructure features and mechanical properties of Ti(C,N)-based cermets. When the Mo 2 C/(Mo 2 C + WC) ratio increases, the Ti(C,N) grains become finer with smaller black cores surrounded by thinner rims, and the structure of cermets tends to be more compact with smaller binder mean free path. Owing to the medium grains and moderate rims, the cermets with a Mo 2 C/(Mo 2 C + WC) ratio of 0.4 exhibit better mechanical properties, and can be chosen as the tool material for machining 42CrMo steel due to the lower Mo content. - Highlights: • Mo 2 C/(Mo 2 C + WC) ratios affect microstructure and mechanical properties of cermets. • Grains become fine and structure of cermets tends to be compact with raised Mo 2 C. • The cermets with a Mo 2 C/(Mo 2 C + WC) ratio of 0.4 can be used to machine 42CrMo steel

Elastic properties and 2D icosahedral bonding in borides of hexagonal WC type

International Nuclear Information System (INIS)

Music, Denis; Schneider, Jochen M.

2005-01-01

Using ab initio calculations we have identified materials with bulk moduli comparable to cubic BN. These are WB, IrB, ReB and OsB crystallizing in the hexagonal WC structure. In the (0 0 0 2) planes of these compounds, we find 2D icosahedral bonding between adjacent B atoms, which has previously not been reported

Elastic properties and 2D icosahedral bonding in borides of hexagonal WC type

Energy Technology Data Exchange (ETDEWEB)

Music, Denis [Materials Chemistry, RWTH-Aachen, Kopernikusstr. 16, D-52074 Aachen (Germany)]. E-mail: music@mch.rwth-aachen.de; Schneider, Jochen M. [Materials Chemistry, RWTH-Aachen, Kopernikusstr. 16, D-52074 Aachen (Germany)

2005-01-15

Using ab initio calculations we have identified materials with bulk moduli comparable to cubic BN. These are WB, IrB, ReB and OsB crystallizing in the hexagonal WC structure. In the (0 0 0 2) planes of these compounds, we find 2D icosahedral bonding between adjacent B atoms, which has previously not been reported.

Hip-Hop to Health Jr. for Latino preschool children.

Science.gov (United States)

Fitzgibbon, Marian L; Stolley, Melinda R; Schiffer, Linda; Van Horn, Linda; KauferChristoffel, Katherine; Dyer, Alan

2006-09-01

Hip-Hop to Health Jr. was a diet/physical activity intervention designed to reduce gains in BMI (kilograms per meter squared) in preschool minority children. Twelve predominantly Latino Head Start centers participated in a group-randomized trial conducted between Fall 2001 and Winter 2003. Six centers were randomized to a culturally proficient 14-week (three times weekly) diet/physical activity intervention. Parents participated by completing weekly homework assignments. The children in the other six centers received a general health intervention that did not address either diet or physical activity. The primary outcome was change in BMI, and secondary outcomes were changes in dietary intake and physical activity. Measures were collected at baseline, post-intervention, and at Years 1 and 2 follow-up. There were no significant differences between intervention and control schools in either primary or secondary outcomes at post-intervention, Year 1, or Year 2 follow-ups. When Hip-Hop to Health Jr. was conducted in predominantly black Head Start centers, it was effective in reducing subsequent increases in BMI in preschool children. In contrast, when the program was conducted in Latino centers, it was not effective. Although the intervention did not prevent excessive weight gain in Latino children, it was very well received. Future interventions with this population may require further cultural tailoring and a more robust parent intervention.

New results on the relationship between hardness and fracture toughness of WC-Co hardmetal

CSIR Research Space (South Africa)

O'Quigley, DGF

1996-05-01

Full Text Available Two sets of WC-Co grades were produced, with cobalt content ranging from 3 to 50 wt.%. The mean grain size of the two sets was 2.2 and 6 mu m respectively. The two sets of grades were used to investigate the relationship between hardness...

Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

International Nuclear Information System (INIS)

Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong; Lee, Changhee; Woo, WanChuck; Park, Sunhong

2015-01-01

Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

Residual stress and crack initiation in laser clad composite layer with Co-based alloy and WC + NiCr

Energy Technology Data Exchange (ETDEWEB)

Lee, Changmin; Park, Hyungkwon; Yoo, Jaehong [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Changhee, E-mail: chlee@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Woo, WanChuck [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Park, Sunhong [Research Institute of Industrial Science & Technology, Hyo-ja-dong, Po-Hang, Kyoung-buk, San 32 (Korea, Republic of)

2015-08-01

Highlights: • Major problem, clad cracking in laser cladding process, was researched. • Residual stress measurements were performed quantitatively by neutron diffraction method along the surface of specimens. • Relationship between the residual stress and crack initiation was showed clearly. • Ceramic particle effect in the metal matrix was showed from the results of residual stress measurements. • Initiation sites of generating clad cracks were specifically studied in MMC coatings. - Abstract: Although laser cladding process has been widely used to improve the wear and corrosion resistance, there are unwanted cracking issues during and/or after laser cladding. This study investigates the tendency of Co-based WC + NiCr composite layers to cracking during the laser cladding process. Residual stress distributions of the specimen are measured using neutron diffraction and elucidate the correlation between the residual stress and the cracking in three types of cylindrical specimens; (i) no cladding substrate only, (ii) cladding with 100% stellite#6, and (iii) cladding with 55% stellite#6 and 45% technolase40s. The microstructure of the clad layer was composed of Co-based dendrite and brittle eutectic phases at the dendritic boundaries. And WC particles were distributed on the matrix forming intermediate composition region by partial melting of the surface of particles. The overlaid specimen exhibited tensile residual stress, which was accumulated through the beads due to contraction of the coating layer generated by rapid solidification, while the non-clad specimen showed compressive. Also, the specimen overlaid with 55 wt% stellite#6 and 45 wt% technolase40s showed a tensile stress higher than the specimen overlaid with 100% stellite#6 possibly, due to the difference between thermal expansion coefficients of the matrix and WC particles. Such tensile stresses can be potential driving force to provide an easy crack path ways for large brittle fractures

Interfacial reaction in cast WC particulate reinforced titanium metal matrix composites coating produced by laser processing

Science.gov (United States)

Liu, Dejian; Hu, Peipei; Min, Guoqing

2015-06-01

Laser injection of ceramic particle was conducted to produce particulate reinforced metal matrix composites (MMCs) coating on Ti-6Al-4V alloy. Cast WC particle (WCp) was used as injection reinforcement to avoid excessive release of carbon atoms into the melt pool. The interfaces and boundaries between WC and Ti matrix were investigated by electron microscopy study. Compared with single crystal WCp, cast WCp was an appropriate solution to control the reaction products (TiC) in the matrix and the total amount of reaction products was significantly reduced. Irregular-shape reaction layers were formed around cast WCp. The reaction layers consist of a W2C layer and a mixed layer of W and TiC. Such reaction layers are effective in load transfer under an external load.

The iron curtain of WC9 stars

International Nuclear Information System (INIS)

Hucht, K.A. van der; Willis, A.J.

1982-01-01

High resolution (Δlambda approximately equal to 0.1 A) IUE spectra have been obtained of the two WC9 stars HD 164270 and HD 136488, covering the wavelength range lambdalambda1150-2050. The former star shows P Cygni profiles indicating a stellar wind terminal velocity of Vsub(infinity) approximately equal to 1400 km s -1 , and the latter Vsub(infinity) approximately equal to -1800 km s -1 . A common feature in the spectra of both stars is narrow displaced absorptions due to Fe III (UV34) transitions arising from a metastable lower level. These features are displaced at sub-terminal velocities (-830 km s -1 for HD 164270 and -1030 km s -1 for Hd 136488) and are believed to be formed in the deceleration region of their stellar winds. The properties of these inferred Fe III circumstellar shells derived from these data are discussed. (Auth.)

A quality approach to maintain the properties of S235 JR structural carbon steel in Lebanon

International Nuclear Information System (INIS)

Sidawi, J.A.; Al Khatib, H.

2004-01-01

Full text.S235JR carbon steel is one of the most popular steels used in Lebanon. It is imported by steel dealers and is widely used by all fabricators and manufacturers of steels for many structural purposes and applications. This kind of steel has good ductile properties as well as excellent weldability. It is still known by its previous designation St 37-2 or E 24-2. S235JR is produced in many shapes and thicknesses such as steel plates, sheets, angles and different other geometric shapes. Standard chemical and mechanical tests were conducted and reported on S235JR hot-rolled structural low-carbon mild steel specimens collected from Lebanese steel market. The main objective of this work is to assure the compliance of these properties with those set by the steel manufacturer. The above mentioned tests were performed at the laboratories of the Industrial Research Institute (IR) in Lebanon to assure the quality and credibility of the results. related European and American standards were presented as references and compared with the achieved results. Discussion was presented to show the similarities and differences between S235JR steel samples and standard requirements. Some of the reasons for such differences were discussed. Sufficient data was furnished through this work for the public and mainly for the Lebanese Standard Organization LIBNOR to easily adopt and implement the EN 10025:1993 European standard that can be applied in Lebanon concerning the most commonly used hot rolled low carbon structural steel. A follow up concerning adopting and implementing EN 10025:1993 will be briefed

Effectiveness and economic analysis of the whole cell/recombinant B subunit (WC/rbs inactivated oral cholera vaccine in the prevention of traveller's diarrhoea

Directory of Open Access Journals (Sweden)

Diez-Diaz Rosa

2009-05-01

Full Text Available Abstract Background Nowadays there is a debate about the indication of the oral whole-cell/recombinant B-subunit cholera vaccine (WC/rBS in traveller's diarrhoea. However, a cost-benefit analysis based on real data has not been published. Methods A cost-effectiveness and cost-benefit study of the oral cholera vaccine (WC/rBS, Dukoral® for the prevention of traveller's diarrhoea (TD was performed in subjects travelling to cholera risk areas. The effectiveness of WC/rBS vaccine in the prevention of TD was analyzed in 362 travellers attending two International Vaccination Centres in Spain between May and September 2005. Results The overall vaccine efficacy against TD was 42,6%. Direct healthcare-related costs as well as indirect costs (lost vacation days subsequent to the disease were considered. Preventive vaccination against TD resulted in a mean saving of 79.26 € per traveller. Conclusion According to the cost-benefit analysis performed, the recommendation for WC/rBS vaccination in subjects travelling to zones at risk of TD is beneficial for the traveller, regardless of trip duration and visited continent.

Stripping methods studies for HVOF WC-10Co-4Cr coating removal

Science.gov (United States)

Menini, Richard; Salah, Nihad Ben; Nciri, Rachid

2004-04-01

The use of high-velocity oxyfuel (HVOF) cermet coatings is considered to be a valuable and innovative alternative technology to replace Cr(VI) electroplating. Among others, a WC-10Co-4Cr coating is one of the best choices for landing gear components due to its excellent tribology and corrosion properties. The stripping process of such a cermet coating was studied due to its importance for the repair and overhaul of landing gear components. Stripping solutions fulfill the following criteria: keep substrate integrity; exhibit a high strip rate (SR); lead to uniform dissolution; show no galvanic corrosion; and be environmentally friendly. Three different high-strength steel substrates (4340, 300M, and Aermet100) were studied. Five different stripping solutions were selected for the electrochemical study. Only three met the targeted criteria: the meta-nitrobenzane sulfonate-sodium cyanide solution; the Rochelle salt; and a commercial nickel stripper. It was found that the process must be electrolytic, and that ultrasonic agitation is needed to enhance the overall mass transport and removal of WC particles and metallic matrix residues. When choosing the most efficient solution and conditions, the SR was found to be as high as 162 µm h-1, which is a very acceptable SR for productivity sake.

Semi-empirical relationship between the hardness, grain size and mean free path of WC-Co

CSIR Research Space (South Africa)

Makhele-Lekala, L

2001-01-01

Full Text Available , grain size of WC and mean free path in Co was obtained. It was found that the empirical formula fitted our measured hardness well. However, when used against results of other researchers, it did not reproduce them satisfactorily at values higher than...

The functionally graded sintered steel WC-Co-NbC matrix

Energy Technology Data Exchange (ETDEWEB)

Santos, A.A.A.; Silva Junior, J.F. [Universidade Federal do Rio Grande do Norte (UFRN), Natal (Brazil)

2009-07-01

Full text: The high speed steels are used for machining, including cutting tools at high speeds because their wear resistance, high temperature properties and excellent hardness. They are ferrous based alloys of the Fe-C-X component system where X represents a group of elements comprising Cr, W or Mo, V and Co. The aim of this work was to study the feasibility of powder metallurgy technique to develop functionally graded alloy material added by WC, Co and NbC. The morphology of the composite powders and sintered MMC were characterized by scanning electron microscopy and XRD measurements. (author)

Cross-linked PEEK-WC proton exchange membrane for fuel cell

CSIR Research Space (South Africa)

Lou, H

2009-10-01

Full Text Available was added to the 15 wt% of SsPEEK-WC solution in NMP with magnetic stir. The solution was cast on a glass Petri dish. The solvent was then removed in a vacuum oven at 130 °C. The membrane was peeled off from the Petri dish. Thereafter, the membrane... and polyetherketone for fuel cell applications. Journal of Membrane Science, 2001. 185(1): p. 41-58. [6] Kerres, J.A., Development of ionomer membranes for fuel cells. Journal of Membrane Science, 2001. 185(1): p. 3-27. [7] Basile, A.; Paturzo, L.; Iulianelli, A...

The somatostatin receptor 2 antagonist 64Cu-NODAGA-JR11 outperforms 64Cu-DOTA-TATE in a mouse xenograft model

Science.gov (United States)

Rylova, Svetlana N.; Stoykow, Christian; Del Pozzo, Luigi; Abiraj, Keelara; Tamma, Maria Luisa; Kiefer, Yvonne; Fani, Melpomeni; Maecke, Helmut R.

2018-01-01

Copper-64 is an attractive radionuclide for PET imaging and is frequently used in clinical applications. The aim of this study was to perform a side-by-side comparison of the in vitro and in vivo performance of 64Cu-NODAGA-JR11 (NODAGA = 1,4,7-triazacyclononane,1-glutaric acid,4,7-acetic acid, JR11 = p-Cl-Phe-cyclo(D-Cys-Aph(Hor)-D-Aph(cbm)-Lys-Thr-Cys)D-Tyr-NH2), a somatostatin receptor 2 antagonist, with the clinically used sst2 agonist 64Cu-DOTA-TATE ((TATE = D-Phe-cyclo(Cys-Tyr-D-Trp-Lys-Thr-Cys)Thr). In vitro studies demonstrated Kd values of 5.7±0.95 nM (Bmax = 4.1±0.18 nM) for the antagonist 64/natCu-NODAGA-JR11 and 20.1±4.4. nM (Bmax = 0.48±0.18 nM) for the agonist 64/natCu-DOTA-TATE. Cell uptake studies showed the expected differences between agonists and antagonists. Whereas 64Cu-DOTA-TATE (the agonist) showed very effective internalization in the cell culture assay (with 50% internalized at 4 hours post-peptide addition under the given experimental conditions), 64Cu-NODAGA-JR11 (the antagonist) showed little internalization but strong receptor-mediated uptake at the cell membrane. Biodistribution studies of 64Cu-NODAGA-JR11 showed rapid blood clearance and tumor uptake with increasing tumor-to-relevant organ ratios within the first 4 hours and in some cases, 24 hours, respectively. The tumor washout was slow or non-existent in the first 4 hours, whereas the kidney washout was very efficient, leading to high and increasing tumor-to-kidney ratios over time. Specificity of tumor uptake was proven by co-injection of high excess of non-radiolabeled peptide, which led to >80% tumor blocking. 64Cu-DOTA-TATE showed less favorable pharmacokinetics, with the exception of lower kidney uptake. Blood clearance was distinctly slower and persistent higher blood values were found at 24 hours. Uptake in the liver and lung was relatively high and also persistent. The tumor uptake was specific and similar to that of 64Cu-NODAGA-JR11 at 1 h, but release from the tumor

Arecibo and Goldstone radar images of near-Earth Asteroid (469896) 2005 WC1

Science.gov (United States)

Lawrence, Kenneth J.; Benner, Lance A. M.; Brozovic, Marina; Ostro, Steven J.; Jao, Joseph S.; Giorgini, Jon D.; Slade, Martin A.; Jurgens, Raymond F.; Nolan, Michael C.; Howell, Ellen S.; Taylor, Patrick A.

2018-01-01

We report radar observations of near-Earth asteroid (469896) 2005 WC1 that were obtained at Arecibo (2380 MHz, 13 cm) and Goldstone (8560 MHz, 3.5 cm) on 2005 December 14-15 during the asteroid's approach within 0.020 au The asteroid was a strong radar target. Delay-Doppler images with resolutions as fine as 15 m/pixel were obtained with 2 samples per baud giving a correlated pixel resolution of 7.5 m. The radar images reveal an angular object with 100 m-scale surface facets, radar-dark regions, and an estimated diameter of 400 ± 50 m. The rotation of the facets in the images gives a rotation period of ∼2.6 h that is consistent with the estimated period of 2.582 h ± 0.002 h from optical lightcurves reported by Miles (private communication). 2005 WC1 has a circular polarization ratio of 1.12 ± 0.05 that is one of the highest values known, suggesting a structurally-complex near-surface at centimeter to decimeter spatial scales. It is the first asteroid known with an extremely high circular polarization ratio, relatively low optical albedo, and high radar albedo.

THE STRUCTURE AND PROPERTIES OF COMPOSITE LASER CLAD COATINGS WITH Ni BASED MATRIX WITH WC PARTICLES

Directory of Open Access Journals (Sweden)

Zita Iždinská

2010-09-01

Full Text Available In this work, the influence of the processing conditions on the microstructure and abrasive wear behavior of composite laser clad coatings with Ni based matrix reinforced with 50% WC particles is analyzed. Composite powder was applied in the form of coatings onto a mild steel substrate (Fe–0.17% C by different laser powers and cladding speeds. The microstructure of the coatings was analyzed by scanning electron microscopy (SEM. Tribological properties of coatings were evaluated by pin-on-disc wear test. It appeared that the hardness of the matrix of composite coatings decreases with increasing cladding speed. However, wear resistance of composite coatings with decreasing hardness of Ni based matrix increases. Significantly enhanced wear resistance of WC composite coatings in comparison with Ni based coatings is attributed to the hard phase structures in composite coatings.

Isolation and Fermentation of Lactobacillus plantarum JR64 as an Omega 6 Probiotic Producer

Directory of Open Access Journals (Sweden)

Lanjar Sumarno

2011-12-01

Full Text Available Application of lactic acid probiotic bacteria in health food diversification currently is progressing rapidly.  It is encouraged the study of searching the potential strains from local resources (Ponorogo Residence namely noni fruits (badeg pace and noni wine.  Aims of this study were to perform the isolation, identification, and production of  probiotic Lactobacillus sp. JR64 fermentation process as a producer of Omega-6 (ω-6 lowering cholesterol and design of probiotic creamy product.   Beginning stages of research was strains isolating and in-vitro testing, the best result were used in  molecular  identification technology development for the production of metabolites through the manipulation of environmental variation  of glucose 20 g / l, 30 g / l and 40 g / l that influenced the substrate concentration of linoleic acid productivity. The result of new isolates isolation showed that isolates that obtained from noni wine, Lactobacillus plantarum JR64, was potential as probiotic condidate.   The effieciency of fermentation  substrates using  Yx/s and Yp /s  in the exponential phase was the highest value for the fermentation of 24 hours of  Yx/ s; 17.03% and Y p/s; 74.72%, while the results of design and the best formulation for viability cells of lactobacillus  plantarum probiotics JR64 was composed of 15 g and 50g butter 15 g icing sugar as well as during storage of the refrigerant temperature was 8.92 x 108 CFU / ml.  [Key Words : Omega-6,  Lactobacillus plantarum JR64, fermentation

20_99 - 102_BIO 072 Mohammed

African Journals Online (AJOL)

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and diastolic blood pressure in blacks with essential hypertension. J Natl Med. Assoc. 96:310-4. Chobanian, A.V., Bakris, G.L., Black, H.R.,. Cushman, W.C., Green, L.A. and Izzo,. J.L. Jr. (2003). The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure: The.

Laboratorium Study of Asphalt Starbit E-55 Polymer Modified Application on Asphalt Concrete Wearing Course (Ac-Wc

Directory of Open Access Journals (Sweden)

Damianus Kans Pangaraya

2015-09-01

Full Text Available The conventional asphalt road has almost been considered fail to serve the transportation needs. It is indicated by the occurrence of premature damage which is caused by vehicle load and climate. Starbit E-55, the polymer modified bitumen, is formulated to meet the requirement of transport development. Considering those needs, it is important to investigate the feasibility level of that modified bitumen as alternate asphalt instead of the conventional one. This research began with the measurement of the properties of hard layered AC-WC Starbit E-55, then comparing the result to 60/70 penetration of Pertamina asphalt. The next step is then, to determine the converted value so as to be close to that of Pertamina (60/70 penetration. This step is conducted by applying durability and ITS tests on the mixture. Result of the tests showed that hard layered AC-WC Starbit E-55 has better characteristic at 5.7% optimum level asphalt and 6.4% of Pertamina asphalt (60/70 penetration. Starbit E-55 converted level within hard-layered ACWC is 5.6%. The performance test result on immersion with variance of 1, 3, 5, 7 and 14 days shows that durability value of Starbit E-55 AC-WC has better performance. During the process, Starbit E-55 required 15.38% higher energy consumption.

Cyclic oxidation behavior of plasma sprayed NiCrAlY/WC-Co/cenosphere coating

Science.gov (United States)

Mathapati, Mahantayya; Ramesh M., R.; Doddamani, Mrityunjay

2018-04-01

Components working at elevated temperature like boiler tubes of coal and gas fired power generation plants, blades of gas and steam turbines etc. experience degradation owing to oxidation. Oxidation resistance of such components can be increased by developing protective coatings. In the present investigation NiCrAlY-WC-Co/Cenosphere coating is deposited on MDN 321 steel substrate using plasma spray coating. Thermo cyclic oxidation behavior of coating and substrate is studied in static air at 600 °C for 20 cycles. The thermo gravimetric technique is used to approximate the kinetics of oxidation. X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray mapping techniques are used to characterize the oxidized samples. NiCrAlY-WC-Co/Cenosphere coating exhibited lower oxidation rate in comparison to MDN 321 steel substrate. The lower oxidation rate of coating is attributed to formation of Al2O3, Cr2O3, NiO and CoWO4 oxides on the outermost surface.

Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

Directory of Open Access Journals (Sweden)

Andrea Angelastro

2013-01-01

Full Text Available As a surface coating technique, laser cladding (LC has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr composite coatings were fabricated by the multilayer laser cladding technique (MLC. An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

Hermeneutic Haunting: E. D. Hirsch, Jr. and the Ghost of Interpretive Validity

Science.gov (United States)

O'Neill, Linda

2011-01-01

This article applies criteria for validity in interpretation to Eric Donald Hirsch, Jr.'s interpretations of John Dewey. Specifically, three criteria that Hirsch, himself, established in his earlier work are used to evaluate Hirsch's interpretation of John Dewey as a member of a class (romantics) who embraced a naive naturalism (trait) more often…

LANSCE '90: the Manuel Lujan Jr. Neutron Scattering Center

International Nuclear Information System (INIS)

Pynn, Roger

1991-01-01

This paper describes progress that has been made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) during the past two years. Presently, LANSCE provides a higher peak neutron flux than any other pulsed spallation neutron source. There are seven spectrometers for neutron scattering experiments that are operated for a national user program sponsored by the U.S. Department of Energy. Two more spectrometers are under construction. Plans have been made to raise the number of beam holes available for instrumentation and to improve the efficiency of the target/moderator system. (author)

LANSCE '90: The Manuel Lujan Jr. Neutron Scattering Center

International Nuclear Information System (INIS)

Pynn, R.

1990-01-01

This paper describes progress that has been made at the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) during the past two years. Presently, LANSCE provides a higher peak neutron flux than any other pulsed spallation neutron source. There are seven spectrometers for neutron scattering experiments that are operated for a national user program sponsored by the US Department of Energy. Two more spectrometers are under construction. Plans have been made to raise the number of beam holes available for instrumentation and to improve the efficiency of the target/moderator system. 9 refs., 4 figs

Investigation on cored-eutectic structure in Ni60/WC composite coatings fabricated by wide-band laser cladding

Energy Technology Data Exchange (ETDEWEB)

Ma, Qunshuang, E-mail: maqunshuang@126.com; Li, Yajiang, E-mail: yajli@sdu.edu.cn; Wang, Juan, E-mail: jwang@sdu.edu.cn; Liu, Kun, E-mail: liu_kun@163.com

2015-10-05

Highlights: • Perfect composite coatings were fabricated using wide-band laser cladding. • Special cored-eutectic structure was synthesized in Ni60/WC composite coatings. • Cored-eutectic consists of hard carbide compounds and fine lamellar eutectic of M{sub 23}C{sub 6} carbides and γ-Ni(Fe). • Wear resistance of coating layer was significantly improved due to precipitation of M{sub 23}C{sub 6} carbides. - Abstract: Ni60 composite coatings reinforced with WC particles were fabricated on the surface of Q550 steel using LDF4000-100 fiber laser device. The wide-band laser and circular beam laser used in laser cladding were obtained by optical lens. Microstructure, elemental distribution, phase constitution and wear properties of different composite coatings were investigated. The results showed that WC particles were partly dissolved under the effect of wide-band fiber laser irradiation. A special cored-eutectic structure was synthesized due to dissolution of WC particles. According to EDS and XRD results, the inside cores were confirmed as carbides of M{sub 23}C{sub 6} enriched in Cr, W and Fe. These complex carbides were primarily separated out in the molten metal when solidification started. Eutectic structure composed of M{sub 23}C{sub 6} carbides and γ-Ni(Fe) grew around carbides when cooling. Element content of Cr and W is lower at the bottom of cladding layer. In consequence, the eutectic structure formed in this region did not have inside carbides. The coatings made by circular laser beam were composed of dendritic matrix and interdendritic eutectic carbides, lacking of block carbides. Compared to coatings made by circular laser spot, the cored-eutectic structure formed in wide-band coatings had advantages of well-distribution and tight binding with matrix. The uniform power density and energy distribution and the weak liquid convection in molten pool lead to the unique microstructure evolution in composite coatings made by wide-band laser

Eclipses and dust formation by WC9 type Wolf-Rayet stars

Science.gov (United States)

Williams, P. M.

2014-12-01

Visual photometry of 16 WC8-9 dust-making Wolf-Rayet (WR) stars during 2001-2009 was extracted from the All-Sky Automated Survey All Star Catalogue (ASAS-3) to search for eclipses attributable to extinction by dust formed in clumps in our line of sight. Data for a comparable number of dust-free WC6-9 stars were also examined to help characterize the data set. Frequent eclipses were observed from WR 104, and several from WR 106, extending the 1994-2001 studies by Kato et al., but not supporting their phasing the variations in WR 104 with its `pinwheel' rotation period. Only four other stars showed eclipses, WR 50 (one of the dust-free stars), WR 69, WR 95 and WR 117, and there may have been an eclipse by WR 121, which had shown two eclipses in the past. No dust eclipses were shown by the `historic' eclipsers WR 103 and WR 113. The atmospheric eclipses of the latter were observed but the suggestion by David-Uraz et al. that dust may be partly responsible for these is not supported. Despite its frequent eclipses, there is no evidence in the infrared images of WR 104 for dust made in its eclipses, demonstrating that any dust formed in this process is not a significant contributor to its circumstellar dust cloud and suggesting that the same applies to the other stars showing fewer eclipses.

Gino Marinuzzi Jr : electronics and early multimedia mentality in Italy

OpenAIRE

Corbella, M.

2015-01-01

In this essay I reassess the complexity of the convergence between electronic music and media practices in Rome in the 1950s and 1960s, through the reconstruction of the experience of composer Gino Marinuzzi Jr (1920-96). His engagement with technology as a structuring device of compositional processes is fundamental and inescapable, and brings to the fore crucial issues of ‘applied’ music’s troublesome reputation in the Italian cultural discourse. In reviewing Marinuzzi’s biography over the ...

Adhesion at WC/diamond interfaces - A theoretical study

International Nuclear Information System (INIS)

Padmanabhan, Haricharan; Rao, M. S. Ramachandra; Nanda, B. R. K.

2015-01-01

We investigate the adhesion at the interface of face-centered tungsten-carbide (001) and diamond (001) from density-functional calculations. Four high-symmetry model interfaces, representing different lattice orientations for either side of the interface, are constructed to incorporate different degrees of strain arising due to lattice mismatch. The adhesion, estimated from the ideal work of separation, is found to be in the range of 4 - 7 J m −2 and is comparable to that of metal-carbide interfaces. Maximum adhesion occurs when WC and diamond slabs have the same orientation, even though such a growth induces large epitaxial strain at the interface. From electronic structure calculations, we attribute the adhesion to covalent interaction between carbon p-orbitals as well as partial ionic interaction between the tungsten d- and carbon p-orbitals across the interface

Adhesion at WC/diamond interfaces - A theoretical study

Energy Technology Data Exchange (ETDEWEB)

Padmanabhan, Haricharan [Department of Engineering Design, Indian Institute of Technology Madras, Chennai – 600036 (India); Rao, M. S. Ramachandra [Department of Physics and Nano-Functional Materials Technology Centre, Indian Institute of Technology Madras, Chennai – 600036 (India); Nanda, B. R. K., E-mail: nandab@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai – 600036 (India)

2015-06-24

We investigate the adhesion at the interface of face-centered tungsten-carbide (001) and diamond (001) from density-functional calculations. Four high-symmetry model interfaces, representing different lattice orientations for either side of the interface, are constructed to incorporate different degrees of strain arising due to lattice mismatch. The adhesion, estimated from the ideal work of separation, is found to be in the range of 4 - 7 J m{sup −2} and is comparable to that of metal-carbide interfaces. Maximum adhesion occurs when WC and diamond slabs have the same orientation, even though such a growth induces large epitaxial strain at the interface. From electronic structure calculations, we attribute the adhesion to covalent interaction between carbon p-orbitals as well as partial ionic interaction between the tungsten d- and carbon p-orbitals across the interface.

Elastic-Plastic Constitutive Equation of WC-Co Cemented Carbides with Anisotropic Damage

International Nuclear Information System (INIS)

Hayakawa, Kunio; Nakamura, Tamotsu; Tanaka, Shigekazu

2007-01-01

Elastic-plastic constitutive equation of WC-Co cemented carbides with anisotropic damage is proposed to predict a precise service life of cold forging tools. A 2nd rank symmetric tensor damage tensor is introduced in order to express the stress unilaterality; a salient difference in uniaxial behavior between tension and compression. The conventional framework of irreversible thermodynamics is used to derive the constitutive equation. The Gibbs potential is formulated as a function of stress, damage tensor, isotropic hardening variable and kinematic hardening variable. The elastic-damage constitutive equation, conjugate forces of damage, isotropic hardening and kinematic hardening variable is derived from the potential. For the kinematic hardening variable, the superposition of three kinematic hardening laws is employed in order to improve the cyclic behavior of the material. For the evolution equation of the damage tensor, the damage is assumed to progress by fracture of the Co matrix - WC particle interface and by the mechanism of fatigue, i.e. the accumulation of microscopic plastic strain in matrix and particles. By using the constitutive equations, calculation of uniaxial tensile and compressive test is performed and the results are compared with the experimental ones in the literature. Furthermore, finite element analysis on cold forward extrusion was carried out, in which the proposed constitutive equation was employed as die insert material

Effect of surface texturing on friction properties of WC/Co cemented carbide

International Nuclear Information System (INIS)

Wu, Ze; Deng, Jianxin; Xing, Youqiang; Cheng, Hongwei; Zhao, Jun

2012-01-01

Highlights: ► Tribological properties of surface textured WC/Co cemented carbide were studied. ► Textured surfaces have better performance of antifriction and antiwear. ► Area density of textures has significant effect on tribological performance. -- Abstract: An experimental study was carried out to investigate the tribological properties of different surface textured WC/Co cemented carbide. The influence of applied load, sliding speed and area density of textures on frictional performance of surface textured patterns was investigated by Taguchi method. Results show that the textured surfaces filled with molybdenum disulfide solid lubricants can reduce the average friction coefficient, wear rates of Ti–6Al–4V alloy balls and adhesion of Ti–6Al–4V alloy materials on the worn track of cemented carbide compared with un-textured ones. Variance analysis of the experimental data indicates that the area density of textures plays major contribution of both average friction coefficient and wear rate of Ti–6Al–4V alloy balls. Higher area density of textures is beneficial to improve tribological performance of the cemented carbide samples. Sliding speed seems to have no effect on the tribological performance of textured surfaces within the reliability interval of 90%. Applied load has effect on both average friction coefficient and wear rate of Ti–6Al–4V alloy balls at the reliability interval of 95%.

Sharing the Gift of Jazz: An Interview with Willie L. Hill Jr.

Science.gov (United States)

Howe, Brad

2011-01-01

This article presents an interview with Willie L. Hill Jr., founder and director of the Society for Jazz Education. Currently a professor of music education at the University of Massachusetts-Amherst and the director of the UMass Fine Arts Center, Hill has served as director of education for the Thelonious Monk Institute of Jazz. He is a past…

THE EFFECT OF PRESSURE, BIAS VOLTAGE AND ANNEALING TEMPERATURE ON N₂ AND N₂+SiH₄ DOPED WC/C DC MAGNETRON SPUTTERED LAYERS

Directory of Open Access Journals (Sweden)

Peter Hornak

2017-12-01

Full Text Available Tungsten carbide (WC/C layers are often researched due to their outstanding mechanical and tribological properties. Here, optimized indented hardness (HIT, indentation modulus (EIT and coefficient of friction (COF values were measured to study the effect of pressure and bias voltage on WC/C layers, deposited on Si by DC magnetron spluttering. Maximal values of HIT=37.2±4.8 GPa, EIT=447±28 GPa and COF=0.64±0.09 were obtained. Additionally, the effect of temperature on optimized layers deposited with and without N₂ and N₂+SiH₄ annealed at 200 °C, 500 °C and 800 °C, were also investigated. The values of HIT, EIT and COF and, observed morphology and structural composition of these contaminated and non-contaminated WC/C layers were evaluated. It was found that layer degradation occurred at different rates depending on the temperature and gas mixture used during the annealing and deposition process, respectively.

Effect of Mo{sub 2}C/(Mo{sub 2}C + WC) weight ratio on the microstructure and mechanical properties of Ti(C,N)-based cermet tool materials

Energy Technology Data Exchange (ETDEWEB)

Xu, Qingzhong; Zhao, Jun, E-mail: zhaojun@sdu.edu.cn; Ai, Xing; Qin, Wenzhen; Wang, Dawei; Huang, Weimin

2015-11-15

To optimize the Mo{sub 2}C content in Ti(C,N)-based cermet tool materials used for cutting the high-strength steel of 42CrMo (AISI 4140/4142 steel), the cermets with different Mo{sub 2}C/(Mo{sub 2}C + WC) weight ratios were prepared. And the microstructure and mechanical properties of cermets were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and measurements of transverse rupture strength (TRS), Vickers hardness (HV) and fracture toughness (K{sub IC}). The results indicate that the Mo{sub 2}C/(Mo{sub 2}C + WC) ratios have great influences on the microstructure features and mechanical properties of Ti(C,N)-based cermets. When the Mo{sub 2}C/(Mo{sub 2}C + WC) ratio increases, the Ti(C,N) grains become finer with smaller black cores surrounded by thinner rims, and the structure of cermets tends to be more compact with smaller binder mean free path. Owing to the medium grains and moderate rims, the cermets with a Mo{sub 2}C/(Mo{sub 2}C + WC) ratio of 0.4 exhibit better mechanical properties, and can be chosen as the tool material for machining 42CrMo steel due to the lower Mo content. - Highlights: • Mo{sub 2}C/(Mo{sub 2}C + WC) ratios affect microstructure and mechanical properties of cermets. • Grains become fine and structure of cermets tends to be compact with raised Mo{sub 2}C. • The cermets with a Mo{sub 2}C/(Mo{sub 2}C + WC) ratio of 0.4 can be used to machine 42CrMo steel.

Military Integration as a Factor for Post-Conflict Stability and Reconciliation: Rwanda, 1994-2005

Science.gov (United States)

2006-09-01

slow down developmental programs, such as cultivation of land and grazing of animals . An estimated 80-110 million mines are believed to be planted in...Reality? The three social groups existed in pre-colonial Rwanda, but the question is whether these groups were cohesive ethnic groups or mythological ...reported that “we can see Caucasian skulls, and beautiful Greek profiles side by side with Semitic and Jewish features, elegant golden-red beauties

75 FR 53861 - Airworthiness Directives; Robert E. Rust, Jr. Model DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk...

Science.gov (United States)

2010-09-02

... Airworthiness Directives; Robert E. Rust, Jr. Model DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk 22, and DH.C1...). ACTION: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for all Robert E. Rust... CFR part 39) to include an AD that would apply to all Robert E. Rust, Jr. Models DeHavilland DH.C1...

Investigations of mussel-inspired polydopamine deposition on WC and Al{sub 2}O{sub 3} particles: The influence of particle size and material

Energy Technology Data Exchange (ETDEWEB)

Mondin, Giovanni, E-mail: giovanni.mondin@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Haft, Marcel, E-mail: m.haft@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Solid State Research, Helmholtzstr. 20, 01069 Dresden (Germany); Wisser, Florian M., E-mail: florian.wisser@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Leifert, Annika, E-mail: annika.leifert@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Mohamed-Noriega, Nasser, E-mail: nasser.mohamed-noriega@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Dörfler, Susanne, E-mail: susanne.doerfler@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Hampel, Silke, E-mail: s.hampel@ifw-dresden.de [Leibniz Institute for Solid State and Materials Research (IFW) Dresden, Institute for Solid State Research, Helmholtzstr. 20, 01069 Dresden (Germany); Grothe, Julia, E-mail: stefan.kaskel@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany); Kaskel, Stefan, E-mail: julia.grothe@chemie.tu-dresden.de [Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden (Germany)

2014-12-15

Polydopamine, formed by oxidation of dopamine, is a bioinspired polymer developed for multifunctional coatings by Lee et al. in 2007 by drawing inspiration from the adhesive proteins found in mussels. Due to their high versatility and substrate-independence, polydopamine coatings are gaining considerable attention in a plethora of research fields, particularly in the coating of particles, but systematic investigations of the polydopamine coating process are lacking in the literature. In this study, we explore by TEM and thermogravimetric analysis the polydopamine coating process on alumina microparticles, tungsten carbide microparticles and tungsten carbide nanoparticles. By choosing two substrates with similar size but different material (Al{sub 2}O{sub 3} and WC), as well as two substrates of the same material but different size (WC micro- and nanoparticles) we investigate the effects of both substrate material and substrate size, in order to gain some insights into the polydopamine particle coating process. As opposed to what is generally assumed in the literature, we found that the polydopamine coating thicknesses on particles, as well as the thickness growing trend, depend on the particles size and material. In particular, after 24 h of polymerization time the polydopamine coatings reached a thickness of 65 ± 10 nm in the case of Al{sub 2}O{sub 3} microparticles, 18 ± 4 nm in the case of WC microparticles and 33 ± 6 nm in the case of WC nanoparticles. - Highlights: • The coating of different particles with polydopamine was systematically investigated. • Al{sub 2}O{sub 3} microparticles and WC microparticles and nanoparticles were investigated. • The thickness of the polydopamine coating depends on the particle size. • The thickness of the polydopamine coating depends on the particle material.

Martin Luther King, Jr., General Hospital and community involvement.

Science.gov (United States)

Humphrey, M M

1973-07-01

Community involvement is not just one facet of the new Martin Luther King, Jr., General Hospital's existence. It is the mainstream from which all other activities flow. In addition to meeting the conventional needs of a conventional hospital staff with the core collection of texts and journals, this library goes one step further. It acts as a resource for its community health workers, dietitians, and nurses in their various outreach programs. It serves as a stimulus for the high school or community college student who may be curious about a health career. It also finds time to provide reading material for its patients.

Lamellipodia and Membrane Blebs Drive Efficient Electrotactic Migration of Rat Walker Carcinosarcoma Cells WC 256.

Science.gov (United States)

Sroka, Jolanta; Krecioch, Izabela; Zimolag, Eliza; Lasota, Slawomir; Rak, Monika; Kedracka-Krok, Sylwia; Borowicz, Pawel; Gajek, Marta; Madeja, Zbigniew

2016-01-01

The endogenous electric field (EF) may provide an important signal for directional cell migration during wound healing, embryonic development and cancer metastasis but the mechanism of cell electrotaxis is poorly understood. Additionally, there is no research addressing the question on the difference in electrotactic motility of cells representing various strategies of cell movement-specifically blebbing vs. lamellipodial migration. In the current study we constructed a unique experimental model which allowed for the investigation of electrotactic movement of cells of the same origin but representing different modes of cell migration: weakly adherent, spontaneously blebbing (BC) and lamellipodia forming (LC) WC256 cells. We report that both BC and LC sublines show robust cathodal migration in a physiological EF (1-3 V/cm). The directionality of cell movement was completely reversible upon reversing the field polarity. However, the full reversal of cell direction after the change of EF polarity was much faster in the case of BC (10 minutes) than LC cells (30 minutes). We also investigated the distinct requirements for Rac, Cdc42 and Rho pathways and intracellular Ca2+ in electrotaxis of WC256 sublines forming different types of cell protrusions. It was found that Rac1 is required for directional movement of LC to a much greater extent than for BC, but Cdc42 and RhoA are more crucial for BC than for LC cells. The inhibition of ROCK did not affect electrotaxis of LC in contrast to BC cells. The results also showed that intracellular Ca2+ is essential only for the electrotactic reaction of BC cells. Moreover, inhibition of MLCK and myosin II did not affect the electrotaxis of LC in contrast to BC cells. In conclusion, our results revealed that both lamellipodia and membrane blebs can efficiently drive electrotactic migration of WC 256 carcinosarcoma cells, however directional migration is mediated by different signalling pathways.

The evaluation of microstructure and mechanical properties of sintered sub-micron WC-Co powders

International Nuclear Information System (INIS)

Nor Izan Izura; Mohd Asri Selamat; Noraizham Mohamad Diah; Talib Ria Jaafar

2007-01-01

A cemented tungsten carbide (WC-Co) is widely used for a variety of machining, cutting, drilling and other applications. The properties of this tungsten heavy alloy are sensitive to processing and degraded by residual porosity. The sequence of high end powder metallurgy process include mixing, compacting and followed by multi-atmosphere sintering of green compact were analyzed. The sub micron (<1.0 μm) and less than 10.0 μm of WC powders are sintered with a metal binder 6% Co to provide pore-free part. The powder compacts were sintered at temperatures cycle in the range of 1200 degree Celsius-1550 degree Celsius in nitrogen-based sintering atmosphere. To date, however there have been few reported studies in the literature that the best sintering was carried out via liquid phase sintering in vacuum at approximately 1500 degree Celsius. from this study we found that in order to attain high mechanical properties, a fine grain size of powder is necessary. Therefore, the attention of this work is to develop and produce wear resistant component with better properties or comparable to the commercial ones. (author)

Nd:YOV4 laser polishing on WC-Co HVOF coating

Science.gov (United States)

Giorleo, L.; Ceretti, E.; Montesano, L.; La Vecchia, G. M.

2017-10-01

WC/Co coatings are widely applied to different types of components due to their extraordinary performance properties including high hardness and wear properties. In industrial applications High Velocity Oxy-Fuel (HVOF) technique is extensively used to deposit hard metal coatings. The main advantage of HVOF compared to other thermal spray techniques is the ability to accelerate the melted powder particles of the feedstock material at a relatively high velocity, leading to obtain good adhesion and low porosity level. However, despite the mentioned benefits, the surface finish quality of WC-Co HVOF coatings results to be poor (Ra higher than 5 µm) thus a mechanical polishing process is often needed. The main problem is that the high hardness of coating leads the polishing process expensive in terms of time and tool wear; moreover polishing becomes difficult and not always possible in case of limited accessibility of a part, micro dimensions or undercuts. Nowadays a different technique available to improve surface roughness is the laser polishing process. The polishing principle is based on focused radiation of a laser beam that melts a microscopic layer of surface material. Compared to conventional polishing process (as grinding) it ensures the possibility of avoiding tool wear, less pollution (no abrasive or liquids), no debris, less machining time and coupled with a galvo system it results to be more suitable in case of 3D complex workpieces. In this paper laser polishing process executed with a Nd:YOV4 Laser was investigated: the effect of different process parameters as initial coating morphology, laser scan speed and loop cycles were tested. Results were compared by a statistical approach in terms of average roughness along with a morphological analysis carried out by Scanning Electron Microscope (SEM) investigation coupled with EDS spectra.

The study of stiffness modulus values for AC-WC pavement

Science.gov (United States)

Lubis, AS; Muis, Z. A.; Iskandar, T. D.

2018-02-01

One of the parameters of the asphalt mixture in order for the strength and durability to be achieved as required is the stress-and-strain showing the stiffness of a material. Stiffness modulus is a very necessary factor that will affect the performance of asphalt pavements. If the stiffness modulus value decreases there will be a cause of aging asphalt pavement crack easily when receiving a heavy load. The high stiffness modulus asphalt concrete causes more stiff and resistant to bending. The stiffness modulus value of an asphalt mixture material can be obtained from the theoretical (indirect methods) and laboratory test results (direct methods). For the indirect methods used Brown & Brunton method, and Shell Bitumen method; while for the direct methods used the UMATTA tool. This study aims to determine stiffness modulus values for AC-WC pavement. The tests were conducted in laboratory that used 3 methods, i.e. Brown & Brunton Method, Shell Bitumen Method and Marshall Test as a substitute tool for the UMATTA tool. Hotmix asphalt made from type AC-WC with pen 60/70 using a mixture of optimum bitumen content was 5.84% with a standard temperature variation was 60°C and several variations of temperature that were 30, 40, 50, 70 and 80°C. The stiffness modulus value results obtained from Brown & Brunton Method, Shell Bitumen Method and Marshall Test which were 1374,93 Mpa, 235,45 Mpa dan 254,96 Mpa. The stiffness modulus value decreases with increasing temperature of the concrete asphalt. The stiffness modulus value from the Bitumen Shell method and the Marshall Test has a relatively similar value.The stiffness modulus value from the Brown & Brunton method is greater than the Bitumen Shell method and the Marshall Test, but can not measure the stiffness modulus value at temperature above 80°C.

N +-implantation induced enhanced adhesion in WC1-x/Ti-6Al-4V

Science.gov (United States)

Laidani, Nadhira; Dorigoni, Carla; Miotello, Antonio

1996-12-01

In this work, the potentiality of the N +-implantation to promote adhesion in WC1-x/Ti-6Al-4V bilayers has been investigated. The WC 1- x films were deposited by rf sputtering in Ar discharge. N +-implantations were performed at 160 keV with ion dose ranging from 5 × 10 15 to 2 × 10 17N +/cm 2. The implantations have been carried out at two sample temperatures: 363 K and 423 K. Adhesion strength was measured by means of the scratch test in conjunction with scanning electron microscopy and energy dispersive spectrometry (EDS). Auger electron spectroscopy (AES), Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD) analyses were used to study the chemical, compositional and structural changes of the WC1-x/Ti-6Al-4V interface. As a general result, N +-implantation modifies the adhesion failure mechanism which from adhesive, before implantation, becomes cohesive. The implantation temperature had a strong effect on the critical loads Lc. N +-implantation at 423 K resulted in a slight increase of Lc, from 2N (unimplanted systems) to 5N for all ion doses. This weak improvement of the adhesion strength was associated with the particular interface processes which allowed C, but not W, mixing into the substrate. In this case, TiC bondings formed which contributed to the substrate embrittlement. When the implantations were carried out at 363 K, both C and W underwent mixing with Ti-6Al-4V: this favoured not only an interface composition grading but also a graded chemistry across the interface, with a strong increase of Lc for low ion dose ( Lc = 14N for 1 × 10 16 N +/cm 2). Implantation with higher doses (5 × 10 16N -/cm 2 and 2 × 10 17N +/cm 2) exhibited lower efficiency ( Lc = 7N for 2 × 10 17 N +/cm 2). This ion dose dependence of the adhesion strength was attributed to the formation of different phases across the interface, probably structurally incompatible.

Influence of electrical discharge machining on the tribological characteristics of WC-Co alloys; Influencia de la electroerosion sobre las caracteristicas tribologicas de materiales compuestos WC-Co

Energy Technology Data Exchange (ETDEWEB)

Casas, B.; Martinez, E.; Esteve, J.; Anglada, M.; Llanes, L.

2001-07-01

The influence of electrical discharge machining (EDM) on the abrasive wear resistance of two WC-10 %{sub w}tCo cemented carbides with different carbide grain size has been studied. Different surface finish conditions were evaluated corresponding to sequential EDM as well as grinding and polishing with diamond. The abrasive wear resistance was determined through microscratch measurements using a nano indentation system. Contrary to the results obtained from hardness measurements, this techniques allows to discern tribological differences among the distinct surface finish conditions studied. Finally, the abrasive wear resistance degradation associated with sequential EDM is discussed as a function of microstructure in terms of a damage parameters. (Author) 9 refs.

Characterisation of Pristine and Recoated electron beam evaporation plasma-assisted physical vapour deposition Cr-N coatings on AISI M2 steel and WC-Co substrates

International Nuclear Information System (INIS)

Avelar-Batista, J.C.; Spain, E.; Housden, J.; Fuentes, G.G.; Rebole, R.; Rodriguez, R.; Montala, F.; Carreras, L.J.; Tate, T.J.

2005-01-01

This paper is focussed on the characterisation of electron beam evaporation plasma-assisted physical vapour deposition Cr-N coatings deposited on AISI M2 steel and hardmetal (K10) substrates in two different conditions: Pristine (i.e., coated) and Recoated (i.e., stripped and recoated). Analytical methods, including X-ray diffraction (XRD), scanning electron microscopy, scratch adhesion and pin-on-disc tests were used to evaluate several coating properties. XRD analyses indicated that both Pristine and Recoated coatings consisted of a mixture of hexagonal Cr 2 N and cubic CrN, regardless of substrate type. For the M2 steel substrate, only small differences were found in terms of coating phases, microstructure, adhesion, friction and wear coefficients between Pristine and Recoated. Recoated on WC-Co (K10) exhibited a less dense microstructure and significant inferior adhesion compared to Pristine on WC-Co (K10). The wear coefficient of Recoated on WC-Co was 100 times higher than those exhibited by all other specimens. The results obtained confirm that the stripping process did not adversely affect the Cr-N properties when this coating was deposited onto M2 steel substrates, but it is clear from the unsatisfactory tribological performance of Recoated on WC-Co that the stripping process is unsuitable for hardmetal substrates

Validation of HVOF WC/Co Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Aircraft Landing Gear

National Research Council Canada - National Science Library

Sartwell, Bruce

2004-01-01

.... This document constitutes the final report on a project to quality high-velocity oxygen-fuel (HVOF) thermal spray WC/Co coatings as a replacement for hard chrome plating on landing gear components...

Nanoindentation study of WC-12Co hardmetals obtained from nanocrystalline powders: Evaluation of hardness and modulus on individual phases

International Nuclear Information System (INIS)

Bonache, V.; Rayon, E.; Salvador, M.D.; Busquets, D.

2010-01-01

With the development of finer hardmetals, the study of mechanical properties of the different constituents down the micrometric level is a question of concern for materials optimization. Nanoindentation has been developed in last years in order to cope with mechanical characterisation at the nanolevel, but difficulties on phase detection are an issue. In the present work, individual hardness and Young's modulus of the constituents of WC-12Co composite were obtained by the use of very shallow nanoindentations (30 nm depth), with the aid of in situ 3D imaging to identify these. By this method three different phases at the sub-micrometric level have been identified and characterised: namely cobalt matrix, tungsten carbide and η phase. The presence of the latter phase and its characterisation is of paramount importance in understanding the behaviour of hardmetals. Values of hardness from 8 (cobalt matrix) to 25 GPa (η phase) have been obtained. Also, for these phases Young's modulus varied from 250 to 400 GPa respectively. Furthermore, it is firstly reported these values for the WC prismatic planes {1 0 1 0} being in the range of 40-55 and 700-900 GPa respectively. These values decrease to a hardness in the range of 25-30 GPa and modulus in the range from 450 to 550 GPa for the WC basal plane {0 0 0 1}.

Martin Luther King, Jr.: A Lesson with Interdisciplinary Connections for Middle-Level Music Students.

Science.gov (United States)

Early, Mary Frances; Terry, Cynthia

This lesson begins with a very brief biography of Martin Luther King, Jr. The lesson identifies its educational objectives; addresses National Standards for Music Education; lists materials needed; details six step-by-step classroom procedures for lesson implementation; and provides curriculum connections for language arts, visual art, physical…

Production and mechanical properties of sintered carbides (hard steels WC-Co)

International Nuclear Information System (INIS)

Batalha, G.F.

1987-09-01

Densification and mechanical characteristics or WC-Co Cemented Carbides, were investigated by dilatometry, Hardness and bending tests, as a function of the two principal micro-structural parameters: the cobalt content and the particle size of carbide crystals. Vickers hardness of the studied compositions showed a linear variation with the increase of the cobalt content. By three point bending, the transverse rupture strenght increases with cobalt content, however, for larger grain size reaches a maximum, eventually reduced by brittle phases and incomplete dispersion. The results of brittle facture tests were statistically analised and fitted better to the 'Weakest Link Model' (Weibull distribution) than the 'Chain Model' (Gaussian distribution). (author) [pt

Validation study of the COBRA-WC computer program for LMFBR core thermal-hydraulic analysis

International Nuclear Information System (INIS)

Khan, E.U.; Bates, J.M.

1982-01-01

The COBRA-WC (Whole Core) computer program has been developed as a benchmark code to predict flow and temperature fields in LMFBR rod bundles. Consequently, an extensive validation study has been conducted to reinforce its credibility. A set of generalized parameters predicts data well for a wide range of geometries and operating conditions which include conventional (current generation LMFBRs) fuel and blanket assembly geometry in the forced, mixed, and natural convection regimes. The data base used for validating COBRA-WC was obtained from out-of-pile and in-pile tests. Most of the data was obtained in fully heated bundles with bundle power skew across flats up to 3:1 (max:min), Reynolds number between 500 and 80,000, and coolant mixed-mean temperature rise (δ anti T) in the range, 78 0 F less than or equal to δ anti T less than or equal to 340 0 F. Within the bundle, 95% of the predicted coolant temperature data points fall within +-25 0 F for 150 0 F less than or equal to δ anti T less than or equal to 340 0 F and within +-17 0 F for 78 0 F less than or equal to δ anti T less than or equal to 150 0 F

Comparative assessment of cyclic J-R curve determination by different methods in a pressure vessel steel

Energy Technology Data Exchange (ETDEWEB)

Chowdhury, Tamshuk, E-mail: tamshuk@gmail.com [Deep Sea Technologies, National Institute of Ocean Technology, Chennai, 600100 (India); Sivaprasad, S.; Bar, H.N.; Tarafder, S. [Fatigue & Fracture Group, Materials Science and Technology Division, CSIR-National Metallurgical Laboratory, Jamshedpur, 831007 (India); Bandyopadhyay, N.R. [School of Materials Science and Engineering, Indian Institute of Engineering, Science and Technology, Shibpur, Howrah, 711103 (India)

2016-04-15

Cyclic J-R behaviour of a reactor pressure vessel steel using different methods available in literature has been examined to identify the best suitable method for cyclic fracture problems. Crack opening point was determined by moving average method. The η factor was experimentally determined for cyclic loading conditions and found to be similar to that of ASTM value. Analyses showed that adopting a procedure analogous to the ASTM standard for monotonic fracture is reasonable for cyclic fracture problems, and makes the comparison to monotonic fracture results straightforward. - Highlights: • Different methods of cyclic J-R evaluation compared. • A moving average method for closure point proposed. • η factor for cyclic J experimentally validated. • Method 1 is easier, provides a lower bound and direct comparison to monotonic fracture.

Sulfonation of PEEK-WC polymer via chloro-sulfonic acid for potential PEM fuel cell applications

Energy Technology Data Exchange (ETDEWEB)

Iulianelli, A.; Clarizia, G.; Gugliuzza, A.; Ebrasu, D.; Basile, A. [Institute on Membrane Technology, ITM-CNR, c/o University of Calabria, Via P. Bucci, Cubo 17/C, 87030 Rende (CS) (Italy); Bevilacqua, A. [Research Centre Italsistemi S.r.l., Via Avogadro, 88900 Crotone (KR) (Italy); Trotta, F. [Department of Organic Chemistry, University of Torino, C.So M. D' Azeglio 48, 10125 Torino (TO) (Italy)

2010-11-15

The preparation and characterization of thin dense sulfonated poly-ether-ether-ketone with cardo group (PEEK-WC) membranes for proton exchange membrane fuel cell (PEMFC) applications are described. The sulfonation of PEEK-WC polymer was realized via chloro-sulfonic acid and different kinds of membrane samples were prepared with a sulfonation degree ranging from 67 to 99%. The degree of sulfonation, homogeneity and thickness significantly affect both the membrane transport properties and the electrochemical performances. The dense character of the membranes was confirmed by SEM analysis. Proton conductivity measurements were carried out in a temperature range from 30 to 80 C and at 100% of relative humidity, reaching 5.40 x 10{sup -3} S/cm{sup -1} as best value at 80 C and with a sulfonation degree (DS) of 99%. At the same conditions, a water uptake of 17% was achieved. DSC and TGA characterizations were used in order to determine the thermal stability of the membranes, confirming a T{sub g} ranging between 206 and 216 C depending on the DS, whereas FT-IR yielded indication about intermolecular interactions and water uptake at various sulfonation degrees. (author)

Friction and wear properties of Ti6Al4V/WC-Co in cold atmospheric plasma jet

International Nuclear Information System (INIS)

Xu Wenji; Liu Xin; Song Jinlong; Wu Libo; Sun Jing

2012-01-01

Highlights: ► Cold plasma jet can effectively reduce the friction coefficients of Ti6Al4V/WC-Co friction pairs. ► Cold plasma jet can easily form nitrides on the surface of Ti6Al4V and on new surfaces generated by tool wear. ► The nitrides can reduce the friction coefficients and protect the friction surface. - Abstract: The friction and wear properties of Ti6Al4V/WC-Co friction pair were studied using an autonomous atmospheric pressure bare electrode cold plasma jet generating device and block-on-ring friction/wear tester, respectively. The study was conducted under air, air jet, nitrogen jet, air cold plasma jet, and nitrogen cold plasma jet atmospheres. Both nitrogen cold and air cold plasma jets effectively reduced the friction coefficients of the friction pairs and decreased friction temperature. The friction coefficient in the nitrogen cold plasma jet decreased to almost 60% compared with that in the air. The scanning electron microscope, energy-dispersive X-ray spectroscope, and X-ray diffraction analyses illustrated that adhesive wear was relieved and the friction surfaces of Ti6Al4V were smoother, both in the nitrogen cold and air cold plasma jets. The roughness value R a of the Ti6Al4V friction surfaces can reach 1.107 μm. A large number of nitrogen particles in the ionic and excited states contained by cold plasma jets reacts easily on the friction surface to produce a large amount of nitrides, which can excellently reduce the wear of Ti6Al4V/WC-Co friction pairs in real-time.

Lamellipodia and Membrane Blebs Drive Efficient Electrotactic Migration of Rat Walker Carcinosarcoma Cells WC 256

Science.gov (United States)

Sroka, Jolanta; Krecioch, Izabela; Zimolag, Eliza; Lasota, Slawomir; Rak, Monika; Kedracka-Krok, Sylwia; Borowicz, Pawel; Gajek, Marta; Madeja, Zbigniew

2016-01-01

The endogenous electric field (EF) may provide an important signal for directional cell migration during wound healing, embryonic development and cancer metastasis but the mechanism of cell electrotaxis is poorly understood. Additionally, there is no research addressing the question on the difference in electrotactic motility of cells representing various strategies of cell movement—specifically blebbing vs. lamellipodial migration. In the current study we constructed a unique experimental model which allowed for the investigation of electrotactic movement of cells of the same origin but representing different modes of cell migration: weakly adherent, spontaneously blebbing (BC) and lamellipodia forming (LC) WC256 cells. We report that both BC and LC sublines show robust cathodal migration in a physiological EF (1–3 V/cm). The directionality of cell movement was completely reversible upon reversing the field polarity. However, the full reversal of cell direction after the change of EF polarity was much faster in the case of BC (10 minutes) than LC cells (30 minutes). We also investigated the distinct requirements for Rac, Cdc42 and Rho pathways and intracellular Ca2+ in electrotaxis of WC256 sublines forming different types of cell protrusions. It was found that Rac1 is required for directional movement of LC to a much greater extent than for BC, but Cdc42 and RhoA are more crucial for BC than for LC cells. The inhibition of ROCK did not affect electrotaxis of LC in contrast to BC cells. The results also showed that intracellular Ca2+ is essential only for the electrotactic reaction of BC cells. Moreover, inhibition of MLCK and myosin II did not affect the electrotaxis of LC in contrast to BC cells. In conclusion, our results revealed that both lamellipodia and membrane blebs can efficiently drive electrotactic migration of WC 256 carcinosarcoma cells, however directional migration is mediated by different signalling pathways. PMID:26863616

Lamellipodia and Membrane Blebs Drive Efficient Electrotactic Migration of Rat Walker Carcinosarcoma Cells WC 256.

Directory of Open Access Journals (Sweden)

Jolanta Sroka

Full Text Available The endogenous electric field (EF may provide an important signal for directional cell migration during wound healing, embryonic development and cancer metastasis but the mechanism of cell electrotaxis is poorly understood. Additionally, there is no research addressing the question on the difference in electrotactic motility of cells representing various strategies of cell movement-specifically blebbing vs. lamellipodial migration. In the current study we constructed a unique experimental model which allowed for the investigation of electrotactic movement of cells of the same origin but representing different modes of cell migration: weakly adherent, spontaneously blebbing (BC and lamellipodia forming (LC WC256 cells. We report that both BC and LC sublines show robust cathodal migration in a physiological EF (1-3 V/cm. The directionality of cell movement was completely reversible upon reversing the field polarity. However, the full reversal of cell direction after the change of EF polarity was much faster in the case of BC (10 minutes than LC cells (30 minutes. We also investigated the distinct requirements for Rac, Cdc42 and Rho pathways and intracellular Ca2+ in electrotaxis of WC256 sublines forming different types of cell protrusions. It was found that Rac1 is required for directional movement of LC to a much greater extent than for BC, but Cdc42 and RhoA are more crucial for BC than for LC cells. The inhibition of ROCK did not affect electrotaxis of LC in contrast to BC cells. The results also showed that intracellular Ca2+ is essential only for the electrotactic reaction of BC cells. Moreover, inhibition of MLCK and myosin II did not affect the electrotaxis of LC in contrast to BC cells. In conclusion, our results revealed that both lamellipodia and membrane blebs can efficiently drive electrotactic migration of WC 256 carcinosarcoma cells, however directional migration is mediated by different signalling pathways.

Wear evaluation of WC inserts coated with TiN/TiAlN multinanolayers

OpenAIRE

Moreno, L. H.; Ciacedo, J. C.; Martinez, F.; Bejarano, G.; Battaille, T. S.; Prieto, P.

2010-01-01

TiN/TiAlN multilayers were deposited by radio frequency, r.f., reactive magnetron sputtering by using titanium and aluminum targets with 10 cm diameter and 99.99% purity in an argon/nitrogen atmosphere, applying a substrate temperature of 300 ºC. WC inserts were used as substrates to improve the mechanical and tribological properties of TiN/TiAlN multilayered coatings compared to other types of coatings like TiAlN monolayers and to manage greater efficiency of these coatings in different indu...

Friction and wear properties of high-velocity oxygen fuel sprayed WC-17Co coating under rotational fretting conditions

Science.gov (United States)

Luo, Jun; Cai, Zhenbing; Mo, Jiliang; Peng, Jinfang; Zhu, Minhao

2016-05-01

Rotational fretting which exist in many engineering applications has incurred enormous economic loss. Thus, accessible methods are urgently needed to alleviate or eliminate damage by rotational fretting. Surface engineering is an effective approach that is successfully adopted to enhance the ability of components to resist the fretting damage. In this paper, using a high-velocity oxygen fuel sprayed (HVOF) technique WC-17Co coating is deposited on an LZ50 steel surface to study its properties through Vickers hardness testing, scanning electric microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffractrometry (XRD). Rotational fretting wear tests are conducted under normal load varied from 10 N to 50 N, and angular displacement amplitudes vary from 0.125° to 1°. Wear scars are examined using SEM, EDX, optical microscopy (OM), and surface topography. The experimental results reveal that the WC-17Co coating adjusted the boundary between the partial slip regime (PSR) and the slip regime (SR) to the direction of smaller amplitude displacement. As a result, the coefficients of friction are consistently lower than the substrate's coefficients of friction both in the PSR and SR. The damage to the coating in the PSR is very slight. In the SR, the coating exhibits higher debris removal efficiency and load-carrying capacity. The bulge is not found for the coating due to the coating's higher hardness to restrain plastic flow. This research could provide experimental bases for promoting industrial application of WC-17Co coating in prevention of rotational fretting wear.

Laser surface alloying of aluminium with WC+Co+NiCr for improved wear resistance

CSIR Research Space (South Africa)

Nath, S

2012-03-01

Full Text Available Department of Metallurgical & Materials Engineering, IIT Kharagpur, West Bengal, India 2National Laser Centre, CSIR, Pretoria, South Africa Abstract In the present study, laser surface alloying of aluminium with WC+Co+NiCr (in the ratio of 70... be used for dispersion of ceramic materials into metallic matrix and hence, form a ceramic dispersed metal matrix composite on metallic substrate [3]. The advantages of laser surface alloying include refinement of the microstructure, uniform dispersion...

Cicero's de legibus and Martin Luther King, Jr.’s Stride toward freedom

Directory of Open Access Journals (Sweden)

Boleslav s. Povšič

1979-12-01

Full Text Available He who reads carefully Cicero'sDe Legibus and Martin Luther King, Jr.'s Stride Toward Freedom is surprised to find, mutatis mutandis, on how many points these two great men agree. The historical circumstances are different, but the essential ideas are very similar. The purpose of this paper is to show on what precisely they agree and on what they differ.

1-Methoxy-agroclavine from Penicillium sp. WC75209, a novel inhibitor of the Lck tyrosine kinase.

Science.gov (United States)

Padmanabha, R; Shu, Y Z; Cook, L S; Veitch, J A; Donovan, M; Lowe, S; Huang, S; Pirnik, D; Manly, S P

1998-03-17

A high-throughput screen was developed and implemented to identify inhibitors of the Lck tyrosine kinase. This report describes the identification of a specific inhibitor of this enzyme from the solid fermentation culture of the Penicillium sp., WC75209. The active compound was isolated and structurally characterized as 1-methoxy-5R, 10S-agroclavine, a new member of the ergot alkaloid family.

Microestructura y propiedades mecánicas de carburos cementados de wc-nbc-co

OpenAIRE

Centeno, Oscarly; Sáez, Adolfredo; Piñero, María A; Castro, Gustavo; Barrios, Estebán; Arenas, Freddy J

2008-01-01

Se evaluó la densificación, fases constituyentes y cambios microestructurales, dureza y tenacidad de una serie de sólidos de WC-NbC-10%Co, con porcentajes nominales en peso de NbC variable entre 0 y 20%. Los sólidos estudiados fueron manufacturados mediante técnicas convencionales de pulvimetalurgia. La caracterización microestructural de los compactos sinterizados fue realizada utilizando Difracción de Rayos X (DRX), Microscopia Electrónica de Barrido (MEB) y Análisis Químico de Rayos X por ...

Has the Dream Been Fulfilled? Dr. Martin Luther King, Jr. & President Barack Hussein Obama

Science.gov (United States)

Robinson, Nichelle Boyd; Moore, Virginia J.; Williams-Black, Thea H.

2015-01-01

Equality for all was the dream of Dr. Martin Luther King, Jr. and he knowingly laid the foundation for and inspired the first African-American President of the United States of America, Barack Hussein Obama, who also had the dream of "Change" for America. These men exhibited how working together can make dreams become reality. For the…

A Long View of the Literary Debate: E. D. Hirsch Jr. and His Forebears.

Science.gov (United States)

Reynolds, Richard J.

An immediate best seller when it was published in 1987, E. D. Hirsch, Jr.'s "Cultural Literacy: What Every American Needs To Know" galvanized legions on both sides of the sociopolitical aisle that divides education. The book has become a revered text regularly referenced by those scholars who take up a position that may be loosely…

Success as Failure and Failure as Success: The Cultural Literacy of E. D. Hirsch, Jr.

Science.gov (United States)

Sledd, Andrew E.; Sledd, James H.

1989-01-01

Examines the logic and rhetoric of E. D. Hirsch, Jr., in "Cultural Literacy." Attempts to answer the question of how intellectual failure guarantees success in the marketplace. Concludes with an alternative vision of the American society that Hirsch describes and the suggestion that Hirsch's cultural literacy is cross-cultural…

The role of La2O3 in direct laser sintering of submicrometre WC-Cop/Cu MMCs

International Nuclear Information System (INIS)

Gu Dongdong; Shen Yifu

2008-01-01

This paper presents a detailed investigation of the influence of rare earth (RE) oxide (La 2 O 3 ) addition on densification and microstructure of direct laser sintered submicrometre WC-Co p /Cu metal matrix composites (MMCs) possessing 50.0 wt% reinforcement (WC-Co). It was found that with increasing La 2 O 3 addition to a suitable amount (1.0 wt%), the particulate dispersion was homogenized and the particulate/matrix interfacial bonding was improved. However, with an excessive addition of La 2 O 3 (1.5 wt%), a heterogeneous microstructure consisting of highly accumulated particulates was present. The exact metallurgical roles of RE element in direct laser sintering of particulate reinforced MMCs were addressed. It showed that a proper addition of RE element (i) decreased surface tension of the melt and enhanced solid-liquid wettability; (ii) dragged and/or pinned grain/phase boundaries and resisted grain coarsening and particulate aggregating. However, the balling phenomenon occurred and the activity of RE atoms decreased at an even higher La 2 O 3 content, thereby producing detrimental effects on laser forming ability

Sliding friction of nanocomposite WC1-x/C coatings: transfer film and its influence on tribology.

Science.gov (United States)

Liu, Y; Gubisch, M; Spiess, L; Schaefer, J A

2009-06-01

The transfer film on steel spheres formed in reciprocating sliding against nanocomposite coatings based on nanocrystalline WC1-x in amorphous carbon matrix is characterized and correlated with the tribological properties measured by a precision microtribometer. With the presence of transfer film, a coefficient of friction approximately 0.13 and a depth wear rate approximately 0.35 x 10(-10) m/N.Pass were obtained. The central zone of the transfer film covering approximately 25% of the Hertz contact area is intact while cracks and wear debris are found in the vast peripheral area. It is also heavily oxidized due to the absence of carbon, which is located at the peripherals and acts as lubricants. We propose that the oxidation of WC and adhesion of the oxides to the surface of sphere is the main mechanism for the buildup of the transfer films. With the thickening of the film, the internal stress increases. Under the shear stress, spalling and cracking of the transfer film take place. The overall tribological performance of the coatings is therefore a competing process of buildup and spalling of transfer films.

Astronaut Curtis L. Brown, Jr., pilot, works with his life raft during emergency bailout training

Science.gov (United States)

1996-01-01

STS-77 TRAINING VIEW --- Astronaut Curtis L. Brown, Jr., pilot, works with his life raft during emergency bailout training for crew members in the Johnson Space Centers (JSC) Weightless Environment Training Facility (WET-F). Brown will join five other astronauts for nine days aboard the Space Shuttle Endeavour next month.

Regional mapping of 100 - 999 kWc photovoltaic plants in 2014

International Nuclear Information System (INIS)

Tuille, F.

2014-01-01

This article presents the distribution over the French soil of intermediate photovoltaic plants in mid 2014. The map gives the number of photovoltaic plants, the total connected capacity per region, and the curves of sunlight. The total number of photovoltaic plants with a capacity ranging from 100 to 999 kWc is 2895 totaling 626,5 MWc. Most of these plants (82%) are integrated into the roofs of buildings while 10% are installed on the roofs. 53% of the solar panels are made of polycrystalline photovoltaic cells while 32% are composed on monocrystalline cells and 7% are based on thin film technology. There are very few plants waiting to be connected to the grid which means that this sector is losing its impetus. (A.C.)

Self-propagating high-temperature synthesis of TiC-WC composite materials

International Nuclear Information System (INIS)

Mas-Guindal, M.J.; Contreras, L.; Turrillas, X.; Vaughan, G.B.M.; Kvick, A.; Rodriguez, M.A.

2006-01-01

TiC-WC composites have been obtained in situ by self-propagating high-temperature synthesis (SHS) from a mixture of compacted powders of elemental titanium, tungsten and graphite. The Rietveld method has proved to be a useful tool to quantify the different phases in the reaction and calculate the cell parameters of the solid solution found in the products. The reaction has also been followed in real time by X-ray diffraction at the European Synchrotron Radiation Facility (ESRF ID-11 Materials Science Beamline). The mechanism of the reaction is discussed in terms of the diffusion of liquid titanium to yield titanium carbide with a solid solution of tungsten. The microstructures of the materials obtained by this method are presented

As(III) oxidation by MnO{sub 2} coated PEEK-WC nanostructured capsules

Energy Technology Data Exchange (ETDEWEB)

Criscuoli, Alessandra, E-mail: a.criscuoli@itm.cnr.it [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Majumdar, Swachchha [Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Rd., 700032 Kolkata (India); Figoli, Alberto, E-mail: a.figoli@itm.cnr.it [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Sahoo, Ganesh C. [Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Rd., 700032 Kolkata (India); Bafaro, Patrizia [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Department of Chemical Engineering and Materials, University of Calabria, Via P. Bucci Cubo 42/A, 87030 Rende (CS) (Italy); Bandyopadhyay, Sibdas [Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Rd., 700032 Kolkata (India); Drioli, Enrico [Institute on Membrane Technology, ITM-CNR, Via P. Bucci Cubo 17/C, 87030 Rende (CS) (Italy); Department of Chemical Engineering and Materials, University of Calabria, Via P. Bucci Cubo 42/A, 87030 Rende (CS) (Italy)

2012-04-15

Highlights: Black-Right-Pointing-Pointer Successful preparation of PEEK-WC nanostructured capsules coated by MnO{sub 2}. Black-Right-Pointing-Pointer Preliminary tests of As(III) oxidation carried out in batch. Black-Right-Pointing-Pointer Complete oxidation obtained for feed concentrations of 0.1 and 0.3 ppm. - Abstract: PEEK-WC nanostructured capsules were prepared by the phase inversion technique and used as support for the coating of a manganese dioxide layer. The coating was done by a chemical treatment of the capsules followed by a thermal one. The presence of the MnO{sub 2} layer was confirmed by scanning electron microscopy (SEM), back scattering electron (BSE), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis. The produced capsules were, then, tested for As(III) oxidation in batch. The experiments consisted in treating 165 ml of As(III) solution with 1 g of coated capsules at fixed temperature (15 Degree-Sign C) and pH (5.7-5.8). In particular, the efficiency of the system was investigated for different As(III) concentrations (0.1, 0.3, 0.7 and 1 ppm). For feeds at lower As(III) content (0.1-0.3 ppm), tests lasted for 8 h, while prolonged runs (up to 48 h) were carried out on more concentrated solutions (0.7 and 1 ppm). The produced capsules were able to oxidize As(III) into As(V) leading to complete conversion after 3 and 4 h for feed concentrations of 0.1 and 0.3 ppm, respectively.

76 FR 71048 - Sixth Annual Philip S. Chen, Jr. Distinguished Lecture on Innovation and Technology Transfer

Science.gov (United States)

2011-11-16

... present ``Treatment of Cancer with Recombinant Immunotoxins: From Technology Transfer to the Patient.'' Dr. Pastan is an NIH Distinguished Investigator and Chief, Laboratory of Molecular Biology, National Cancer Institute Center for Cancer Research. This annual series honors Dr. Philip S. Chen, Jr. for his almost 50...

Erosion-oxidation behavior of thermal sprayed Ni20Cr alloy and WC and Cr3C2 cermet coatings

Directory of Open Access Journals (Sweden)

Clarice Terui Kunioshi

2005-06-01

Full Text Available An apparatus to conduct high temperature erosion-oxidation studies up to 850 °C and with particle impact velocities up to 15 m.s-1 was designed and constructed in the Corrosion Laboratories of IPEN. The erosion-oxidation behavior of high velocity oxy fuel (HVOF sprayed alloy and cermet coatings of Ni20Cr, WC 20Cr7Ni and Cr3C2 Ni20Cr on a steel substrate has been studied. Details of this apparatus and the erosion-oxidation behavior of these coatings are presented and discussed. The erosion-oxidation behavior of HVOF coated Cr3C2 25(Ni20Cr was better than that of WC 20Cr7Ni, and the erosion-oxidation regimes have been identified for these coatings at particle impact velocity of 3.5 m.s-1, impact angle of 90° and temperatures in the range 500 to 850 °C.

UTILIZATION OF TORAY FLY ASH AS FILLER SUBSTITUTION IN THE HOT ROLLED SHEET-WEARING COURSE (HRS-WC MIXTURE

Directory of Open Access Journals (Sweden)

F. Candra

2012-02-01

Full Text Available In road construction materials, the utilization of fly ash as additive materials is limited and also small in quantity, while the disposal of fly ash is quite high. An abundance of fly ash can be found at PT Toray Company in Jakarta and Surabaya. Toray fly ash is disposed coal ash resulting from coal-fired electricity generating power plants. Toray fly ash in this research is used as substitute mineral filler in asphalt paving mixtures. Research on utilization of Toray fly ash as filler is conducted in the Hot Rolled Sheet – Wearing Course Mixture.  Filler content in the HRS –WC mixture is 9%. Variations of Toray fly ash in the mixture tested are 0%, 25%, 50%, 75%, 100% and the variations of asphalt content are 6%, 6.5%, 7%, 7.5%, 8%. Marshall test is  performed to determine the Optimum Asphalt Content  and Marshall Stability, Indirect Tensile Strength (ITS test and Tensile Strength Ratio (TSR to select the optimum Toray fly ash utilization in the mixture based on the moisture susceptibility of specimens. The research results show that in variations of 0%, 25%, 50%, 75% and 100% Toray fly ash in the HRS-WC Mixture, the Optimum Asphalt Contents are at 6.8%, 7.0%, 7.0%, 7.1% and 7.6%  and Marshall Stability values of the variations are 1649 kg, 1541 kg, 1568 kg, 1678 kg, 1718 kg respectively. TSR values in variations of Toray fly ash are 98.32%, 90.28%, 89.38%, 87.62%, 64.71% respectively, with Minimum TSR value required is 80%. Based on the overall parameters, the optimum Toray fly ash utilization in the HRS-WC Mixture recommended is 75% of Toray fly ash at 7.1% Optimum Asphalt Content.

Influence of powder and spray parameters on erosion and corrosion properties of HVOF sprayed WC-Co-Cr coatings

Energy Technology Data Exchange (ETDEWEB)

Berget, John

1998-07-01

Thermal spraying is a generic term including various processes used to deposit coatings on surfaces. The coating material is in the form of powder or a wire and is melted or softened by means of a heat source. A gas stream accelerates the material towards a prepared surface and deposits it there to form the coating. Examples of components being maintained by application of thermal spray coatings are gate valves and ball valves for the offshore industry and turbine blades in power generations installations. Recent investigation has shown that the commonly used coating material WC-Co is not corrosion resistant. But it can be improved by the addition of Cr. The main objective of this thesis is to study the influence of spray process control variables and powder characteristics on the erosion and erosion-corrosion properties of the coatings. Spray process variables investigated include energy input, powder feed rate and spray distance. Powder characteristics studied are average size of the WC particles, relative proportions of Co and Cr in the metal phase and powder grain size distribution.

The effect of w/c ratio on microstructure of self-compacting concrete (SCC) with sugarcane bagasse ash (SCBA)

Science.gov (United States)

Hanafiah, Saloma, Victor, Amalina, Khoirunnisa Nur

2017-11-01

Self-Compacting Concrete (SCC) is a concrete that can flow and compact by itself without vibrator. The ability of SCC to flow by itself makes this concrete very suitable for construction that has very small reinforcement gaps. In this study, SCC was designed to get a compressive strength above 60 MPa at the age of 28 days. Sugarcane bagasse ash was used as substitution material for cement replacement. Percentages of sugarcane bagasse ash used were 10%, 15%, and 20%. There were three w/c values that vary from 0.275, 0.300, and 0.325. Testing standards referred to ASTM, EFNARC and ACI. The fresh concrete test was slump flow, L-box and V-funnel. The maximum compressive strength was in the mixture with the sugarcane bagasse ash composition of 15% and w/c=0.275 which was 67.24 MPa. The result of SEM test analysis found that the mixture composition with 15% sugarcane bagasse ash has solid CSH structure, small amount of pores, and smaller pore diameter than other mixtures.

Ultra-short-period WC/SiC multilayer coatings for x-ray applications

International Nuclear Information System (INIS)

Fernández-Perea, Mónica; Pivovaroff, Mike J.; Soufli, Regina; Alameda, Jennifer; Mirkarimi, Paul; Descalle, Marie-Anne; Baker, Sherry L.; McCarville, Tom; Ziock, Klaus; Hornback, Donald; Romaine, Suzanne; Bruni, Ric; Zhong, Zhong; Honkimäki, Veijo; Ziegler, Eric; Christensen, Finn E.; Jakobsen, Anders C.

2013-01-01

Multilayer coatings enhance x-ray mirror performance at incidence angles steeper than the critical angle, allowing for improved flux, design flexibility and facilitating alignment. In an attempt to extend the use of multilayer coatings to photon energies higher than previously achieved, we have developed multilayers with ultra-short periods between 1 and 2 nm based on the material system WC/SiC. This material system was selected because it possesses very sharp and stable interfaces. In this article, we show highlights from a series of experiments performed in order to characterize the stress, microstructure and morphology of the multilayer films, as well as their reflective performance at photon energies from 8 to 384 keV

Crystal orientation mapping applied to the Y-TZP/WC composite

CERN Document Server

Faryna, M; Sztwiertnia, K

2002-01-01

Crystal orientation measurements made by electron backscattered diffraction (EBSD) in the scanning electron microscope (SEM) and microscopic observations provided the basis for a quantitative investigation of microstructure in an yttria stabilized, tetragonal zirconia-based (Y-TZP) composite. Automatic crystal orientation mapping (ACOM) in a SEM can be preferable to transmission electron microscopy (TEM) for microstructural characterization, since no sample thinning is required, extensive crystal data is already available, and the analysis area is greatly increased. A composite with a 20 vol.% tungsten carbide (WC) content was chosen since it revealed crystal relationships between the matrix and carbide phase already established by TEM analysis. However, this composite was difficult to investigate in the EBSD/ SEM since it is non-conductive, the Y-TZP grain size is of the order of the system resolution, and the sample surface, though carefully prepared, reveals a distinctive microtopography. In this paper, so...

Macroparticle generation in DC arc discharge from a WC cathode

Science.gov (United States)

Zhirkov, Igor; Polcik, Peter; Kolozsvári, Szilard; Rosen, Johanna

2017-03-01

We have studied macroparticle generation from a tungsten carbide cathode used in a dc vacuum arc discharge. Despite a relatively high decomposition/melting point (˜3100 K), there is an intensive generation of visible particles with sizes in the range 20-35 μm. Visual observations during the discharge and scanning electron microscopy of the cathode surface and of collected macroparticles indicate a new mechanism for particle formation and acceleration. Based on the W-C phase diagram, there is an intensive sublimation of carbon from the melt resulting from the cathode spot. The sublimation supports the formation of a sphere, which is accelerated upon an explosion initiated by Joule heating at the critical contact area between the sphere and the cathode body. The explosive nature of the particle acceleration is confirmed by surface features resembling the remains of a splash on the droplet surface.

Study of interface correlation in W/C multilayer structure by specular and non-specular grazing incidence X-ray reflectivity measurements

Energy Technology Data Exchange (ETDEWEB)

Biswas, A., E-mail: arupb@barc.gov.in; Bhattacharyya, D.; Sahoo, N. K. [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Maidul Haque, S.; Tripathi, S.; De, Rajnarayan [Atomic and Molecular Physics Division, Bhabha Atomic Research Centre, VIZAG Centre, Visakhapatnam 530012 (India); Rai, S. [Indus Synchrotron Utilization Division, Raja Raman Centre for Advanced Technology, Indore 452013 (India)

2015-10-28

W/C/W tri-layer thin film samples have been deposited on c-Si substrates in a home-built Ion Beam Sputtering system at 1.5 × 10{sup −3} Torr Ar working pressure and 10 mA grid current. The tri-layer samples have been deposited at different Ar{sup +} ion energies between 0.6 and 1.2 keV for W layer deposition and the samples have been characterized by specular and non-specular grazing incidence X-ray reflectivity (GIXR) measurements. By analyzing the GIXR spectra, various interface parameters have been obtained for both W-on-C and C-on-W interfaces and optimum Ar{sup +} ion energy for obtaining interfaces with low imperfections has been found. Subsequently, multilayer W/C samples with 5-layer, 7-layer, 9-layer, and 13-layer have been deposited at this optimum Ar{sup +} ion energy. By fitting the specular and diffused GIXR data of the multilayer samples with the parameters of each interface as fitting variables, different interface parameters, viz., interface width, in-plane correlation length, interface roughness, and interface diffusion have been estimated for each interface and their variation across the depth of the multilayers have been obtained. The information would be useful in realizing W/C multilayers for soft X-ray mirror application in the <100 Å wavelength regime. The applicability of the “restart of the growth at the interface” model in the case of these ion beam sputter deposited W/C multilayers has also been investigated in the course of this study.

An imitative calculation of W/C, Mo/Si articifial multilayered films' structures and properties as X-ray monochromators

International Nuclear Information System (INIS)

Liu Wen; Liu Wenhan; Wu Ziqin

1989-01-01

An imitative calculation on W/C and Mo/Si artificial multilayered films have been made. The influences of total period numbers and deviation of period thickness on X-ray diffraction peak were given. Two difference diviations, random fluctuation and system linear deviation have been imitated, their influences on X-ray energy distinguish power have been compared

Influence of electrical discharge machining on the tribological characteristics of WC-Co alloys

International Nuclear Information System (INIS)

Casas, B.; Martinez, E.; Esteve, J.; Anglada, M.; Llanes, L.

2001-01-01

The influence of electrical discharge machining (EDM) on the abrasive wear resistance of two WC-10 % w tCo cemented carbides with different carbide grain size has been studied. Different surface finish conditions were evaluated corresponding to sequential EDM as well as grinding and polishing with diamond. The abrasive wear resistance was determined through microscratch measurements using a nano indentation system. Contrary to the results obtained from hardness measurements, this techniques allows to discern tribological differences among the distinct surface finish conditions studied. Finally, the abrasive wear resistance degradation associated with sequential EDM is discussed as a function of microstructure in terms of a damage parameters. (Author) 9 refs

The leadership principles of Dr. Martin Luther King, Jr. and their relevance to surgery.

Science.gov (United States)

Brunicardi, F Charles; Cotton, Ronald T; Cole, George W; Martinez, George

2007-01-01

In order to face the challenges in healthcare this century, it is essential that surgeons understand modern leadership principles. One of the greatest leaders in history was Dr. Martin Luther King, Jr., who provides a shining example of level-5 leadership for us to study. The study of leadership principles of great leaders can provide us with practical methods of conflict resolution as well as inspiration to keep us engaged and focused. As leaders of the medical community, we face numerous challenges, including discovering and implementing new treatments for disease, providing care for the indigent, overcoming educational challenges such as incorporating the ACGME Core Competencies into our surgical training and promoting diversity in education. Achieving these goals is often hindered by the environment in which we labor-nearly 50 million are uninsured, the rising cost of medical care is currently at 16% of the GNP, and reimbursement rates are falling-which makes the practice of surgery a significant challenge. Effective leadership will be paramount in achieving these goals. In this editorial, which summarizes a presentation given to the Surgical Section of the annual National Medical Association meeting, five important leadership principles that are important for surgeons have been selected and related to the outstanding leadership of Dr. Martin Luther King, Jr.

Investigation of cosputtered W--C thin films as diffusion barriers

International Nuclear Information System (INIS)

Yang, H.Y.; Zhao, X.

1988-01-01

Polycrystalline thin films of W--C were deposited on single-crystal Si or SiO 2 substrates by rf planar magnetron cosputtering of graphite (C) and W targets. The performance of cosputtered W 75 C 25 thin films as diffusion barriers between a Si substrate and metallic overlayers of Ag, Au, or Al was investigated. Backscattering spectrometry and x-ray diffraction are used to detect metallurgical interactions. Four-point probe measurement of resistance is employed to monitor the electrical stability of the metallization schemes upon thermal annealing in a vacuum for 30 min in temperature ranges from 500 to 700 0 C. The electrical resistivity of W 75 C 25 films is 140 μΩ cm. A W 75 C 25 layer 1100 A thick prevents metallurgical interdiffusion and reaction between Au or Ag overlayers and the Si substrates up to 700 0 C, and between an Al overlayer and the Si substrate up to 450 0 C.tential

Sintering, microstructure and properties of WC-AISI304 powder composites

International Nuclear Information System (INIS)

Marques, B.J.; Fernandes, C.M.; Senos, A.M.R.

2013-01-01

Highlights: ► Total replacement of Co binder by stainless steel AISI 304 in WC based composites. ► Processing conditions for WC–stainless steel composites. ► Mechanical behavior and oxidation resistance of WC–stainless steel composites. -- Abstract: Tungsten carbide–stainless steel (AISI 304) based composites were successfully prepared by powder metallurgy routes using vacuum sintering at a maximum temperature of 1500 °C. The effects of the binder amount (between 6 and 15 wt.%) on the phase composition, microstructure and mechanical properties, namely hardness and fracture toughness, were investigated. Appreciable amount of (M,W) 6 C up to 12 wt.% was detected, especially for the higher SS contents. However, a good compromise between toughness and hardness was observed. Besides that, improved oxidation resistance was noticed in WC–SS based composites compared with WC–Co composites. The results are discussed having in mind the correlation between chemical composition, phase composition, microstructure and mechanical behavior

Measurement and modeling of room temperature co-deformation in WC-10 wt.%

Energy Technology Data Exchange (ETDEWEB)

Livescu, V. [MST-8/LANSCE, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)]. E-mail: vlivescu@lanl.gov; Clausen, B. [MST-8/LANSCE, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Paggett, J.W. [Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211 (United States); Krawitz, A.D. [Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, MO 65211 (United States); Drake, E.F. [REEDHycalogTM/Grant Prideco, Houston, TX 77252 (United States); Bourke, M.A.M. [MST-8/LANSCE, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2005-06-15

In situ neutron diffraction measurements were performed on a tungsten carbide (WC)-10 wt.% cobalt (Co) cemented carbide composite subjected to compressive loading. The sample was subjected to consecutive load/unload cycles to -500, -1000, -2000 and -2100 MPa. Thermal residual stresses measured before loading reflected large hydrostatic tensile stresses in the binder phase and compressive stresses in the carbide phase. The carbide phase behaved elastically at all but the highest load levels, whereas plasticity was present in the binder phase from values of applied stress as low as -500 MPa. A finite element simulation utilizing an interpenetrating microstructure model showed remarkable agreement with the complex mean phase strain response during the loading cycles despite its under-prediction of thermal residual strains.

Thermomagnetic method to determine cobalt content in solid WC-Co alloys

International Nuclear Information System (INIS)

Tumanov, V.I.; Loshakov, A.L.; Korchakova, E.A.

1980-01-01

A thermomagnetic method of cobalt amount determination in tungsten solid alloys is suggested. The method consists in the following: a sample of solid alloy is placed in a magnetic field sufficient to achieve technical saturation (not less than 10 kOe), and specific magnetization of saturation of the alloy σ is determined, then the sample is heated and according to the curves of magnetic permeability dependence on the temperature the Curie point of the alloy THETA is determined and cobalt amount is calculated by the formula qsub(Co)=σ100/(kTHETA+b). The analysis duration is approximately 30 min. Comparative data of cobalt amount determination in solid alloys WC-Co using thermonagnetic and potentiometric methods are presented. Results obtained by thermomagnetic and chemical method are in good agreement. Efficiency of the thermomagnetic method is much higher

75 FR 16513 - B&C Corporation, JR Engineering Division, Including B&C Distribution Center, Including On-Site...

Science.gov (United States)

2010-04-01

... Engineering Division, Including B&C Distribution Center, Including On-Site Leased Workers From B&C Services... occurred during the relevant time period at the B&C Distribution Center, Inc. of the B&C Corporation, JR Engineering Division, Barberton, Ohio. The B&C Distribution Center provides distribution and logistical...

Pragmatic Analyses of Martin Luther King (Jr)'s Speech: "I Have a Dream"--An Introspective Prognosis

Science.gov (United States)

Josiah, Ubong E.; Oghenerho, Gift

2015-01-01

This paper investigates the speech of Martin Luther King (Jr.) titled: "I Have a Dream", presented in 1963 at the Lincoln Memorial. This speech is selected for use because it involves a speaker and an audience who belong to a particular speech community. The speech is about the failed promises by the Americans whose dream advocate…

Characterizing the Effects of Micro Electrical Discharge Machining Parameters on Material Removal Rate during Micro EDM Drilling of Tungsten Carbide (WC-Co)

Science.gov (United States)

Hourmand, Mehdi; Sarhan, Ahmed A. D.; Sayuti, Mohd

2017-10-01

Micro-dies, molds and miniaturized products can be manufactured using micro EDM process. In this research, EDM machine and on-machine fabricated CuW micro-electrode were utilized to produce the micro holes in WC-16%Co. The effects of voltage, current, pulse ON time, pulse OFF time, capacitor and rotating speed on Material removal rate (MRR) during micro EDM drilling of WC-16% Co was analyzed using fractional factorial design method. ANOVA analysis shows that increasing current, rotating speed, capacitor and decreasing voltage and pulse ON time lead to the amplify in MRR. It was found that out of all the factors, current and capacitor had the most significant effect on MRR, while the effect of capacitor was more than current. Eventually, it can be concluded that micro holes can be produced using EDM machine.

The use of acetonitrile as the sole nitrogen and carbon source by Geotrichum sp. JR1 Uso de acetonitrila como única fonte de carbono e nitrogênio por Geotrichum sp. JR1

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Rachel Passos Rezende

2004-06-01

Full Text Available A yeast strain identified as Geotrichum sp. JR1 was able to use acetonitrile as the sole carbon and nitrogen source. The strain grew in 0.5 to 2M acetonitrile. Ammonia generation as enzymatic product during the strain growth indicates the presence of an acetonitrile degrading enzyme. Acetic acid and acetamide were detected during assays with the resting cells cultivated in acetonitrile, indicating the presence of nitrile and amide degrading enzymes. This paper is the first to describe the use of acetonitrile as the sole carbon and nitrogen source by a yeast.Uma linhagem de levedura identificada como Geotrichum sp. JR1 foi capaz de utilizar acetonitrila, em concentrações de 0,5 a 2M, como única fonte de carbono e de nitrogênio. A geração de amônia durante o crescimento do microrganismo indica a presença de sistema enzimático capaz de degradar acetonitrila. Durante os ensaios enzimáticos, com células cultivadas em acetonitrila, foram detectados ácido acético e acetamida como produtos indicando a presença de sistema enzimático capaz de degradar acetonitrila e acetamida. Este trabalho é o primeiro a descrever a utilização de acetonitrila como única fonte de carbono e de nitrogênio por uma levedura.

An IRAS-Based Search for New Dusty Late-Type WC Wolf-Rayet Stars

Science.gov (United States)

Cohen, Martin

1995-01-01

I have examined all Infrared Astronomical Satellite (IRAS) data relevant to the 173 Galactic Wolf-Rayet (W-R) stars in an updated catalog, including the 13 stars newly discovered by Shara and coworkers. Using the W-R coordinates in these lists, I have examined the IRAS Point Source Catalog (PSC), the Faint Source Catalog, and the Faint Source Reject Catalog, and have generated one-dimensional spatial profiles, 'ADDSCANs', and two-dimensional full-resolution images, 'FRESCOS'. The goal was to assemble the best set of observed IRAS color indices for different W-R types, in particular for known dusty late-type WC Wolf-Rayet (WCL) objects. I have also unsuccessfully sought differences in IRAS colors and absolute magnitudes between single and binary W-R stars. The color indices for the entire ensemble of W-R stars define zones in the IRAS color-color ([12] - [25], [25] - [60])-plane. By searching the PSC for otherwise unassociated sources that satisfy these colors, I have identified potential new W-R candidates, perhaps too faint to have been recognized in previous optical searches. I have extracted these candidates' IRAS low-resolution spectrometer (LRS) data and compared the spectra with the highly characteristic LRS shape for known dusty WCL stars. The 13 surviving candidates must now be ex amined by optical spectroscopy. This work represents a much more rigorous and exhaustive version of the LRS study that identified IRAS 17380 - 3031 (WR98a) as the first new W-R (WC9) star discovered by IPAS. This search should have detected dusty WCL stars to a distance of 7.0 kpc from the Sun, for l is greater than 30 degrees, and to 2.9 kpc even in the innermost galaxy. For free-free-dominated W-R stars the corresponding distances are 2.5 and 1.0 kpc, respectively.

Study, Stance, and Stamina in the Research on Teachers' Lives: A Rejoinder to Robert V. Bullough, Jr.

Science.gov (United States)

Kelchtermans, Geert

2008-01-01

Robert V. Bullough, Jr.'s article demonstrated in an impressive way how autobiographical accounts, as well as single person narratives, are intertwined with much larger issues in society, international politics, and economical interests, as well as consequences for people in general and educators in particular. The way he proves capable of…

Evaluación de las transformaciones estructurales en recubrimientos de WC10Ni depositados por laser cladding sobre acero para herramienta EN 12379

Directory of Open Access Journals (Sweden)

Candel, J. J.

2011-08-01

Full Text Available Carbide metal matrix composite materials are known for a high resistance to all types of wear. It is due to a beneficial combination of properties given by hard phase particles included in a tough matrix. Different kinds of those materials have been employed in the development of new high properties cutting tools. Laser cladding (LC technique allows obtaining an accurate defect-free coating with a low thermal affectation of the component. But in the case of WC cermet coatings due to its high laser absorption and the different mechanical and thermal properties between substrate and coating can appear a wide range of different defects as cracks, pores, massive carbide dilution and lacks of adherence. The aim of the present work is to study the metallurgical transformations during LC process of WC cermet coating on cold work tool steel substrate (EN 12379. Also it has been related process parameters with defects generation. Microstructure and composition of the coating and the heat affected zone have been analysed. Microhardness evolution profile has been obtained. Results show that although process parameters control reduce the generation of defects, in the deposition of overlapped layers appear different metallurgical transformations related with massive WC decomposition and the diffusion of alloying elements from substrate to the coating.

Los materiales compuestos de matriz metálica reforzados con carburos, son conocidos por su elevada resistencia a todos los tipos de desgaste, debido a la combinación de las partículas duras en una matriz metálica tenaz. Diferentes tipos de estos materiales, se han empleado en el desarrollo de nuevas herramientas de corte de altas prestaciones. La técnica de láser cladding (LC, permite obtener recubrimientos libres de defectos sobre zonas muy concretas, con un aporte de calor muy localizado. Pero en el caso de carburos de wolframio (WC, debido a la enorme absorción de energía y la

The Limits of Master Narratives in History Textbooks: An Analysis of Representations of Martin Luther King, Jr.

Science.gov (United States)

Alridge, Derrick P.

2006-01-01

In this study, I argue that American history textbooks present discrete, heroic, one-dimensional, and neatly packaged master narratives that deny students a complex, realistic, and rich understanding of people and events in American history. In making this argument, I examine the master narratives of Martin Luther King, Jr., in high school history…

A expansão e a eficiência da escola rural em São Paulo: atuação e posicionamentos de Almeida Jr. a partir de estatísticas oficiais - The expansion and the efficiency of the rural school in São Paulo: the performance and the thinking of Almeida Jr. based o

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Luciana Maria Viviani

2011-07-01

Full Text Available O objetivo deste estudo é analisar os discursos produzidos por Almeida Jr. sobre o ensino rural, entre as décadas de 1930 e 1940, e as formas sob as quais ele utilizou dados estatísticos para sustentar as suas opiniões e a sua atuação como administrador do ensino paulista. O estudo dessas questões pretende colaborar na ampliação do entendimento acerca das propostas para o ensino rural, tema bastante debatido nesse período. Por meio da análise de publicações oficiais paulistas e de artigos da Revista Brasileira de Estudos Pedagógicos, verificou-se que Almeida Jr., médico e educador ligado ao grupo dos chamados renovadores do ensino, defendia propostas voltadas para a qualidade do ensino e para a organização de uma escola básica comum, ainda que adaptada ao meio rural.Palavras-chave: educação rural, estatísticas educacionais, intelectuais da educação. THE EXPANSION AND THE EFFICIENCY OF THE RURAL SCHOOL IN SÃO PAULO: THE PERFORMANCE AND THE THINKING OF ALMEIDA JR. BASED ON OFFICIAL STATISTICSAbstractThe objective of this paper is to analyze de speeches made by Almeida Jr. about the rural education, between the decades of 1930 and 1940, and the way under which he used the statistics data to sustain his opinions and his performance as the manager of education in São Paulo. By analyzing the São Paulo’s official publications and the articles published in the Revista Brasileira de Estudos Pedagógicos, it has been found that Almeida Jr., a doctor and an educator connected to the group composed by some men who were called the renewers of education, sustained proposals which were bent to the good quality of education and to the organization of a unique elementary school, though to fit the country environment.Key-words: rural education, educational statistics, intellectuals in education. LA EXPANSIÓN Y LA EFICIENCIA DE LA ESCUELA RURAL EN SAN PABLO: ACTUACIÓN Y OPINIONES DE ALMEIDA JR. A PARTIR DE ESTAD�

Obituary: Edward W. Burke, Jr. (1924-2011)

Science.gov (United States)

Bloomer, Raymond, Jr.

2011-12-01

Dr. Edward W. Burke Jr. passed away on June 15, 2011, after suffering a heart attack. Dr. Burke devoted his professional life to the research and teaching of physics and astronomy at King College in Bristol, Tennessee. Edward W. Burke, Jr., was born in Macon, Georgia, on September 16, 1924. He was a Navy veteran, having been commissioned as an ensign in 1944. He served in the Pacific near the end of World War II. He proceeded to complete his undergraduate degree in mathematics from Presbyterian College in 1947 and pursued the M.S. and Ph.D. in physics (1949 and 1954, respectively) at the University of Wisconsin. Under the direction of Professor Julian Mack, his thesis was titled "Isotope Shift in the Spectra of Boron." Although he did research in atomic spectra in the early part of his career, his interest in astronomy and variable stars in particular were his primary interests during his long academic career. Dr. Burke began his illustrious career at King College in 1949. He initiated the astronomy program there in 1950, included constructing a 12.5 inch Newtonian telescope, homemade as was most everything in those days. Many of his students learned about photometry at the Burke Observatory on the college campus. Burke was known for his trips to the Kitt Peak and Lowell observatories accompanied by undergraduate students on his trips, all of which were made by automobile which he preferred over flying. His initial interest in Ap stars later broadened into variable and especially eclipsing binary stars. His motivation was maintained by his desire to have his students experience basic research and to spark their interest in advanced degrees. Numerous students achieved advanced science and medical degrees because of Burke's encouragement and mentoring. In 1959, Dr. Burke was awarded a Fulbright professorship and traveled to Chile where he taught physics for a year in the Engineering School at the University of Chile in Santiago. He worked to establish a physics

Gino Marinuzzi Jr: Electronics and Early Multimedia Mentality in Italy

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Maurizio Corbella

2015-08-01

Full Text Available In this essay I reassess the complexity of the convergence between electronic music and media practices in Rome in the 1950s and 1960s, through the reconstruction of the experience of composer Gino Marinuzzi Jr (1920-96. His engagement with technology as a structuring device of compositional processes is fundamental and inescapable, and brings to the fore crucial issues of ‘applied’ music’s troublesome reputation in the Italian cultural discourse. In reviewing Marinuzzi’s biography over the period 1949-75, my goal is to exemplify the key phases of this transitional period in Italian music history, in which technology, through the spreading of media and their increasing importance in cultural representations, came to constitute a new value of musical activity and at the same time renewed old questions concerning music’s aesthetic autonomy.

Safety analysis report for packaging: the ORNL DOT Specification 20WC-5 - special form packaging

International Nuclear Information System (INIS)

Schaich, R.W.

1982-10-01

The ORNL DOT Specification 20WC-5 - Special Form Package was fabricated for the transport of large quantities of solid nonfissile radioactive materials in special form. The package was evaluated on the basis of tests performed at Sandia National Laboratories, Albuquerque, New Mexico on an identical fire and impact shield and special form tests performed on a variety of stainless steel capsules at ORNL by Operations Division personnel. The results of these evaluations demonstrate that the package is in compliance with the applicable regulations for the transport of large quantities of nonfissile radioactive materials in special form

Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part I: Dry Sliding

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D. Kekes

2014-12-01

Full Text Available The influence of the cermet fraction in cermet/ metal composite coatings developed by High-Velocity Oxyfuel Flame (HVOF spraying on their tribological behaviour was studied. Five series of coatings, each one containing different proportion of cermet-metal components, prepared by premixing commercially available feedstocks of NiCrFeBSiC metallic and WC-Co/Cr cermet powders were deposited on AISI 304 stainless steel substrate. The microstructure of as-sprayed coatings was characterized by partial decomposition of the WC particles, lamellar morphology and micro-porosity among the solidified splats. Tribological behavior was studied under sliding friction conditions using a Si3N4 ball as counterbody and the friction coefficient and volume loss were determined as a function of the cermet fraction. Microscopic examinations of the wear tracks and relevant cross sections identified the wear mechanisms involved. Coatings containing only the metallic phase were worn out through a combination of ploughing, micro-cracking and splat exfoliation, whilst those containing only the cermet phase primarily by micro-cracking at the individual splat scale. The wear mechanisms of the composite coatings were strongly affected by their randomly stratified structure. In-depth cracks almost perpendicular to the coating/ substrate interface occurring at the wear track boundaries resulted in cermet trans-splat fracture.

An SFG and ERS investigation of the corrosion of CoW0.013C0.001 alloys and WC-Co cermets in CN--containing aqueous solutions

International Nuclear Information System (INIS)

Bozzini, Benedetto; Busson, Bertrand; De Gaudenzi, Gian Pietro; D'Urzo, Lucia; Mele, Claudio; Tadjeddine, Abderrahmane

2007-01-01

In order to increase the knowledge of the corrosion mechanism, in situ spectroelectrochemical methodologies were employed in the investigation of the electrochemical interface of WC-Co hardmetals. Together with standard cyclic voltammetries (CV), ElectroReflectance Spectroscopy (ERS) and Sum Frequency Generation (SFG) spectroscopy measurements were performed both on a Co-base alloy, simulating the metallic binder of hardmetal composites, and on a model WC-Co system. A cyanide solution, encountered in the gold extraction industry, was employed as electrolyte. Electrochemical cells and experimental apparatuses were designed to allow in situ experiments. CV measurements showed corrosion attack to run at potentials more anodic than -500 mV vs. Ag/AgCl, both for the alloy and the composite. The high reactivity of the alloy in cyanide environment was witnessed by the time-dependence of the surface vibrational (SFG) and electronic (SFG and ERS) properties under cathodic polarisation. Furthermore, SFG measurements highlighted two different adsorbation sites for cyanide ion, probably α- and ε-Co. The WC-Co system showed a pseudo-passivation peak, typical of the corrosion behaviour of this material, due to precipitation of corrosion products. ERS data at 532 nm showed an ennobling of the potential at which the reflectivity increase was recorded

Studi Karakteristik Campuran Aspal Beton Lapis Aus (AC-WC Menggunakan Aspal Penetrasi 60/70 dengan Penambahan Lateks

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I Nyoman Arya Thanaya

2016-12-01

Full Text Available Asphalt on pavement in long term may undergo hardening, so it needs addition of additive that can make it remain flexible. This experiment tried to produce asphalt concrete wearing course (AC-WC using asphalt penetration 60/70 with the addition of latex, with aim to know the characteristic of AC-WC mix at the optimum of asphalt content with addition of  latex in variation of 0%, 2%, 4%, 6%, 8%, and 10% of the total binder. Latex was initially mixed with the asphalt, then the aggregates were proportioned based on ideal grading. The samples were produced in hotmix process. The density of latex was found 0.977 with dry rubber content of 61.95%. The optimum of asphalt content that was 5.7%, where all Marshall characteristics were met. It was chosen the mix with 4% latex by total binder where all properties of asphalt binder were still met. It was obtained that the Stability value  was 1439.26 kg (≥ 800 kg, Flow 3.84 mm (2-4 mm, Marshall Quotient 379.66 kg / mm (≥ 250 kg / mm, VIM  4.437% (3-5%, VMA 15.280% (≥ 15%, VFB 70.961 (≥ 65%. The mixture that contains latex had better resistance to deformation under dynamic creep loading at 40 °C.

"I Just Want to Do God's Will:" Teaching Martin Luther King, Jr. as a Religious Leader

Science.gov (United States)

Neumann, David

2018-01-01

Teachers often respond to the perils of teaching about religion by simply avoiding the subject. An investigation of secondary lesson plans on three prominent Martin Luther King, Jr. websites reveals little attention to the ideology of the civil rights movement, especially those touching on religious ideas. Ignoring King's religious views risks…

Safety of the recombinant cholera toxin B subunit, killed whole-cell (rBS-WC oral cholera vaccine in pregnancy.

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Ramadhan Hashim

Full Text Available Mass vaccinations are a main strategy in the deployment of oral cholera vaccines. Campaigns avoid giving vaccine to pregnant women because of the absence of safety data of the killed whole-cell oral cholera (rBS-WC vaccine. Balancing this concern is the known higher risk of cholera and of complications of pregnancy should cholera occur in these women, as well as the lack of expected adverse events from a killed oral bacterial vaccine.From January to February 2009, a mass rBS-WC vaccination campaign of persons over two years of age was conducted in an urban and a rural area (population 51,151 in Zanzibar. Pregnant women were advised not to participate in the campaign. More than nine months after the last dose of the vaccine was administered, we visited all women between 15 and 50 years of age living in the study area. The outcome of pregnancies that were inadvertently exposed to at least one oral cholera vaccine dose and those that were not exposed was evaluated. 13,736 (94% of the target women in the study site were interviewed. 1,151 (79% of the 1,453 deliveries in 2009 occurred during the period when foetal exposure to the vaccine could have occurred. 955 (83% out of these 1,151 mothers had not been vaccinated; the remaining 196 (17% mothers had received at least one dose of the oral cholera vaccine. There were no statistically significant differences in the odds ratios for birth outcomes among the exposed and unexposed pregnancies.We found no statistically significant evidence of a harmful effect of gestational exposure to the rBS-WC vaccine. These findings, along with the absence of a rational basis for expecting a risk from this killed oral bacterial vaccine, are reassuring but the study had insufficient power to detect infrequent events.ClinicalTrials.gov NCT00709410.

Determination of J-R curve from only one experimental test on one sample

International Nuclear Information System (INIS)

Lebey, J.; Roche, R.L.

1983-01-01

Increasing attention has been given in fracture mechanics to the use of the J concept not only as a criterion of the onset of crack propagation, but also as an aid in the study of propagation stability. As a consequence, there is a need to determine the variation of J with crack extension, this being usually presented in curves known as J-R curves. Earlier methods for determining such curves used several specimens. The present paper describes a procedure avoiding any direct measurement of the crack length and giving a correct value of J when crack propagation occurs. (author)

Critical Void Volume Fraction fc at Void Coalescence for S235JR Steel at Low Initial Stress Triaxiality

Science.gov (United States)

Grzegorz Kossakowski, Paweł; Wciślik, Wiktor

2017-10-01

The paper is concerned with the nucleation, growth and coalescence of microdefects in the form of voids in S235JR steel. The material is known to be one of the basic steel grades commonly used in the construction industry. The theory and methods of damage mechanics were applied to determine and describe the failure mechanisms that occur when the material undergoes deformation. Until now, engineers have generally employed the Gurson-Tvergaard- Needleman model. This material model based on damage mechanics is well suited to define and analyze failure processes taking place in the microstructure of S235JR steel. It is particularly important to determine the critical void volume fraction fc , which is one of the basic parameters of the Gurson-Tvergaard-Needleman material model. As the critical void volume fraction fc refers to the failure stage, it is determined from the data collected for the void coalescence phase. A case of multi-axial stresses is considered taking into account the effects of spatial stress state. In this study, the parameter of stress triaxiality η was used to describe the failure phenomena. Cylindrical tensile specimens with a circumferential notch were analysed to obtain low values of initial stress triaxiality (η = 0.556 of the range) in order to determine the critical void volume fraction fc . It is essential to emphasize how unique the method applied is and how different it is from the other more common methods involving parameter calibration, i.e. curve-fitting methods. The critical void volume fraction fc at void coalescence was established through digital image analysis of surfaces of S235JR steel, which involved studying real, physical results obtained directly from the material tested.

A new methodology for the evaluation of the J-R curve

International Nuclear Information System (INIS)

Donoso, J. R.; Zahr, J.; Landes, J. D.

2005-01-01

A new methodology for the construction of J-R curves for ductile materials, based upon the analytical integration of the P-ν relation, is presented. This method is based on the Common and Concise Formats, and on a postulated crack growth law, that relates the amount of stable crack growth with plastic displacement. The model developed, denoted asnC and C, reproduces quite well the experimentally obtained P-ν, Δa-ν and J-Δa curves. The results suggest that the amount of stable crack growth in a ductile material follows a power-law behaviour in its dependence with plastic displacement. This methodology may be used to evaluate instability conditions, through the adequate analytical treatment of the P-ν and J-Δa relations. (Author) 35 refs

Health Care Fraud: Characteristics, Sanctions, and Prevention. Briefing Report to the Honorable William V. Roth, Jr., U.S. Senate.

Science.gov (United States)

General Accounting Office, Washington, DC. Accounting and Financial Management Div.

At the request of Senator William Roth, Jr., the General Accounting Office (GAO) reviewed Medicare and Medicaid fraud investigations that agency inspectors general referred to the Department of Justice for prosecution to identify characteristics of alleged fraud against the government and to determine actions taken against those caught defrauding…

Mechanical characterization of cemented carbide WC-6Co (%wt) manufactured by SPS (Spark Plasma Sintering; Caracterizacao mecanica de metal duro WC-6Co (%massa) sinterizado via SPS (Spark Plasma Sintering)

Energy Technology Data Exchange (ETDEWEB)

Boidi, G.; Tertuliano, A.J.; Machado, I.F., E-mail: guido.boidi@usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Engenharia Mecatronica e Sistemas Mecanicos; Rodrigues, D. [BRATS- Filtros Sinterizados e Pos Metalicos, Cajamar, SP (Brazil)

2016-07-01

This work aimed to manufacture cemented carbide (WC-6%wtCo) obtained by SPS (Spark Plasma Sintering) process and to carry out the mechanical characterization by hardness and fracture toughness. The material was consolidated at 1100 deg C for different holding times (1 min, 5 min, 10 min), in order to evaluate the densification. A reference sample was also used to be compared to SPS. Optical and scanning electron microscopy were carried out to characterize the microstructural features of the samples and mechanical properties were obtained by hardness measurements (micro and macro) and instrumented indentation. The fracture toughness was calculated with the method of Palmqvist. Best results were found in the material sintered by SPS for 10 minutes of holding time, in which 97% of relative density and about 1600 HV{sub 10} was reached. (author)

Influence of the microstructure of WC-Co cemented carbides on the fracture toughness and abrasive wear

International Nuclear Information System (INIS)

Zum Gahr, K.H.; Fischer, A.

1981-01-01

Fracture toughness and abrasive wear resistance of WC-Co cemented carbides were investigated by using the indentation cracking test (Palmqvist test) and the pin-on-disk method respectively. Size distribution of tungsten carbides and means free path between them were found to be important microstructural parameters related to the mechanical behavior. Results showed that selection of cemented carbides for heavy wear loading is complicated by contradictory influence of microstructural parameters on fracture toughness and abrasion resistance. Knowledge of the relation between microstructure and resistance to fracture or wear is necessary for optimum use of cemented carbides. (orig.) [de

Effects of Trophic Modes, Carbon Sources, and Salinity on the Cell Growth and Lipid Accumulation of Tropic Ocean Oilgae Strain Desmodesmus sp. WC08.

Science.gov (United States)

Zhao, Zhenyu; Ma, Shasha; Li, Ang; Liu, Pinghuai; Wang, Meng

2016-10-01

The effects of trophic modes, carbon sources, and salinity on the growth and lipid accumulation of a marine oilgae Desmodesmus sp. WC08 in different trophic cultures were assayed by single factor experiment based on the blue-green algae medium (BG-11). The results implied that biomass and lipid accumulation culture process were optimized depending on the tophic modes, sorts, and concentration of carbon sources and salinity in the cultivation. There was no significant difference in growth or lipid accumulation with Na 2 CO 3 amendment or NaHCO 3 amendment. However, Na 2 CO 3 amendment did enhance the biomass and lipid accumulation to some extent. The highest Desmodesmus sp. WC08 biomass and lipid accumulation was achieved in the growth medium with photoautotrophic cultivation, 0.08 g L -1 Na 2 CO 3 amendment and 15 g L -1 sea salt, respectively.

Regional mapping of photovoltaic plants ranging from 100 to 999 kWc in 2013

International Nuclear Information System (INIS)

Anon.

2013-01-01

In a context of the expectation of a strong political lead, small and intermediate photovoltaic installations keep on developing. The map gives for each France's region the number of operating installations whose power output ranges between 100 and 999 kWc, and the number and the capacity of the installations that are completed but not yet connected to the grid. The sunshine level curves are also drawn. Polycrystal and monocrystal technologies are the most used 48% and 32% respectively, while the thin layer technology is used in only 5% of the installations. Concerning the type of the setting a great majority of the installations (85%) are integrated to the building while less than 1% are set on the ground. (A.C.)

IG Statement: Arthur A. Elkins, Jr., on OIG report Early Warning Report: Main EPA Headquarters Warehouse in Landover, Maryland, Requires Immediate EPA Attention

Science.gov (United States)

Statement of Inspector General Arthur A. Elkins, Jr., on the Office of Inspector General (OIG) report Early Warning Report: Main EPA Headquarters Warehouse in Landover, Maryland, Requires Immediate EPA Attention.

Abrasive wear of WC-NiMoCrFeCo thermally sprayed coatings in dependence on different types of abrasive sands

Czech Academy of Sciences Publication Activity Database

Kašparová, M.; Zahálka, F.; Houdková, Š.; Ctibor, Pavel

2010-01-01

Roč. 48, č. 1 (2010), s. 75-85 ISSN 0023-432X R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : WC-Hastelloy * abrasive wear * Al2O3 sand * SiO2 sand * braun size * abrasive efficiency Subject RIV: JG - Metallurgy Impact factor: 0.471, year: 2010 http://kovmat.sav.sk/abstract.php?rr=48&cc=1&ss=73

Southern Vermont College (SVC) and Wheelock College (WC): 2010 Urban and Rural Healthcare Academy Program (HAP) for College Progress and Workforce Development

Science.gov (United States)

DeCiccio, Albert C.

2010-01-01

(Purpose) This is a report about the Urban and Rural Healthcare Academy Pilot Program (HAP) that launched at Southern Vermont College (SVC) and Wheelock College (WC) in summer 2010. HAP enabled 18 vulnerable high school students to learn about how to progress to college, how to transition when they arrive on a college campus, and how to prepare…

Effects of bias voltage and annealing on the structure and mechanical properties of WC0.75N0.25 thin films

International Nuclear Information System (INIS)

Su, Y.D.; Hu, C.Q.; Wen, M.; Wang, C.; Liu, D.S.; Zheng, W.T.

2009-01-01

We investigated the effects of both bias voltage and annealing on the structure and mechanical properties of WC 0.75 N 0.25 thin films, deposited on Si (1 0 0) substrates by a direct current reactive magnetron sputtering system, in which the negative substrate bias voltage (V b ) was varied from floating (-1.6 V) to -200 V, and the deposited films were annealed at 800 deg. C for 2 h. The X-ray photoelectron spectroscopy and selected area electron diffraction analyses, along with the density-functional theory (DFT) calculations on the electronic structure, showed that WC 0.75 N 0.25 films were a single-phase of carbonitrides. After annealing, a significant decrease in hardness for the films was observed, being a result of point-defect annihilation as V b was in the range of floating to -120 V. However, when V b was in the range of -160 to -200 V, the hardness increased from ∼37 GPa for the as-deposited film to a maximum of ∼43 GPa for the annealed one. This increase in hardness after annealing might be attributed to age-hardening.

SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel joints prepared by dynamic diffusion bonding: Microelectrochemical studies in 0.6 M NaCl solution

International Nuclear Information System (INIS)

Andreatta, Francesco; Matesanz, Laura; Akita, Adriano H.; Paussa, Luca; Fedrizzi, Lorenzo; Fugivara, Cecilio S.; Gomez de Salazar, Jose M.; Benedetti, Assis V.

2009-01-01

Corrosion of SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel interfaces was investigated in 0.6 M NaCl solution using an electrochemical microcell, which enables local electrochemical characterization at the micrometer scale. Two pieces of steel, one with a WC-Co coating covered with Ni (12 μm) and Cu (5 μm) layers, and the other with a Ni (15 μm) layer, were welded by dynamic diffusion bonding. A WC-Co coating was applied to the steel by the high velocity oxygen-fuel process, and Ni-Cu and Ni layers by electroplating. Polarization curves were recorded using an electrochemical microcell. Different regions of welded samples were investigated, including steel, cermet coating, and steel/cermet and steel/Ni-Cu-Ni/cermet interfaces. Optical and electronic microscopes were employed to study the corroded regions. Potentiodynamic polarization curves obtained using the microcell revealed that the base metal was more susceptible to corrosion than the cermet. In addition, cermet steel/cermet and steel/Ni-Cu-Ni/cermet joints exhibited different breakdown potentials. Steel was strongly corroded in the regions adjacent to the interfaces, while the cermet was less corroded. Iron oxides/hydroxides and chloride salts were the main corrosion products of steel. After removal of the superficial layer of corrosion products, iron oxides were mainly observed. Chloride ions were detected mainly on a copper-enriched layer placed between two Ni-enriched layers.

An SFG and ERS investigation of the corrosion of CoW{sub 0.013}C{sub 0.001} alloys and WC-Co cermets in CN{sup -}-containing aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Bozzini, Benedetto [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy)]. E-mail: benedetto.bozzini@unile.it; Busson, Bertrand [CLIO-LCP, Batiment 201P2, Universitaire Paris Sud 11, 91420 Orsay Cedex (France); De Gaudenzi, Gian Pietro [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy); D' Urzo, Lucia [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy); Mele, Claudio [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy); Tadjeddine, Abderrahmane [UDIL-CNRS, Batiment 201P1, BP34, 91898 Orsay, Cedex (France)

2007-05-15

In order to increase the knowledge of the corrosion mechanism, in situ spectroelectrochemical methodologies were employed in the investigation of the electrochemical interface of WC-Co hardmetals. Together with standard cyclic voltammetries (CV), ElectroReflectance Spectroscopy (ERS) and Sum Frequency Generation (SFG) spectroscopy measurements were performed both on a Co-base alloy, simulating the metallic binder of hardmetal composites, and on a model WC-Co system. A cyanide solution, encountered in the gold extraction industry, was employed as electrolyte. Electrochemical cells and experimental apparatuses were designed to allow in situ experiments. CV measurements showed corrosion attack to run at potentials more anodic than -500 mV vs. Ag/AgCl, both for the alloy and the composite. The high reactivity of the alloy in cyanide environment was witnessed by the time-dependence of the surface vibrational (SFG) and electronic (SFG and ERS) properties under cathodic polarisation. Furthermore, SFG measurements highlighted two different adsorbation sites for cyanide ion, probably {alpha}- and {epsilon}-Co. The WC-Co system showed a pseudo-passivation peak, typical of the corrosion behaviour of this material, due to precipitation of corrosion products. ERS data at 532 nm showed an ennobling of the potential at which the reflectivity increase was recorded.

On the performances and wear of WC-diamond like carbon coated tools in drilling of CFRP/Titanium stacks

Science.gov (United States)

Boccarusso, L.; Durante, M.; Impero, F.; Minutolo, F. Memola Capece; Scherillo, F.; Squillace, A.

2016-10-01

The use of hybrid structures made of CFRP and titanium alloys is growing more and more in the last years in the aerospace industry due to the high strength to weight ratio. Because of their very different characteristics, the mechanical fastening represent the most effective joining technique for these materials. As a consequence, drilling process plays a key role in the assembly. The one shot drilling, i.e. the contemporary drilling of the stack of the two materials, seems to be the best option both in terms of time saving and assembly accuracy. Nevertheless, due to the considerable different machinability of fiber reinforced plastics and metallic materials, the one shot drilling is a critical process both for the holes quality and for the tools wear. This research was carried out to study the effectiveness of new generation tools in the drilling of CFRP/Titanium stacks. The tools are made of sintered grains of tungsten carbide (WC) in a binder of cobalt and coated with Diamond like carbon (DLC), and are characterized by a patented geometry; they mainly differ in parent WC grain size and binder percentage. Both the cutting forces and the wear phenomena were accurately investigated and the results were analyzed as a function of number of holes and their quality. The results show a clear increase of the cutting forces with the number of holes for all the used drilling tools. Moreover, abrasive wear phenomena that affect initially the tools coating layer were observed.

Material mixing on W/C twin limiter in TEXTOR-94

International Nuclear Information System (INIS)

Tanabe, T.; Ohgo, T.; Wada, M.; Rubel, M.; Philipps, V.; Seggern, J. von; Ohya, K.; Huber, A.; Pospieszczyk, A.; Schweer, B.

2000-01-01

In order to investigate the effect of mutual contamination between tungsten (W) and carbon (C) and its influence on the plasma, a W-C twin test limiter, half made of W and the other half of C, was inserted into the edge plasma of TEXTOR-94 under ohmic and NBI heating conditions. The contamination process was observed by spectroscopy, and the intensity distribution of WI showed migration of W onto the C side by the successive cycles of sputtering and prompt redeposition. On the other hand, the deposition of C on the W surface was not obvious. Most of the hydrogen (deuterium) on the limiter was found to be retained in the deposited layers and that in the deposited C layer much higher than that in the deposited W layer. This indicates that tritium retention is smaller in metallic deposits above 500 K. The AES analysis conducted after the exposure of the test limiter showed that W deposited on C reacted with the substrate to form carbides at higher temperatures. The thickness of carbide layer, and/or the content of W in C were influenced by the temperature and flux distributions, and no carbide layer was formed at the limiter edge where the temperature was relatively low

Edward Sapir e Mattoso Câmara Jr.: intersecçõesDOI:10.5007/1984-8420.2011v12n2p15

Directory of Open Access Journals (Sweden)

Lovania Roehrig Teixeira

2011-03-01

Full Text Available O conceito de linguagem perpassa diferentes abordagens teóricas e diferentes cientistas sem ser, no entanto, consensual na Linguística. Todavia, algumas características similares acerca do fenômeno da linguagem são encontradas nas abordagens de Edward Sapir e Mattoso Câmara Jr., principalmente, por este último ter realizado traduções de duas obras de Sapir e ter convivido diretamente com grandes linguistas estruturalistas, nos Estados Unidos. O presente artigo descreve e discute algumas das principais aproximações entre as ideias de Mattoso Câmara Jr. e Sapir, que sugerem a filiação do primeiro ao segundo. A partir disso, buscaram-se os aspectos de convergência das concepções linguísticas e identificaram-se três, relacionados à (i linguagem e pensamento, (ii linguagem e arte e (iii linguagem e deriva linguística.

Gunshot wounds to the hand. The Martin Luther King, Jr, General Hospital experience.

Science.gov (United States)

Phillips, P; Hansraj, K K; Cox, E E; Ashley, E M

1995-01-01

This article is a retrospective review of patients who presented to Martin Luther King, Jr./Drew Medical Center with gunshot wounds and had either isolated or associated injuries to the hand. The following is an account of those injuries noting the location, soft-tissue or bony involvement, and interventional methods that were implemented in the treatment of these patients who resided primarily in South Central Los Angeles. Prompt evaluation and initiation of treatment is essential in the management of both high- and low-velocity gunshot wounds so as to decrease the potential morbidity that often follows. Society must also look at the prevalence of these injuries and address the underlying issues that often are the root of the acts of violence.

Influence of Plasma Transferred Arc Process Parameters on Structure and Mechanical Properties of Wear Resistive NiCrBSi-WC/Co Coatings

Directory of Open Access Journals (Sweden)

Eitvydas GRUZDYS

2011-07-01

Full Text Available Self-fluxing NiCrBSi and related coatings received considerable interest due to their good wear as well as corrosion resistance at moderate and elevated temperatures. Hard tungsten carbide (WC particles can be included in NiCrBSi for further increase of the coating hardness and abrasive wear resistance. Flame spray technique is widely used for fabrication of NiCrBSi films. However, in such a case, subsequent remelting of the deposited coatings by flame, arc discharge or high power laser beam is necessary. In present study NiCrBSi-WC/Co coatings were formed using plasma transferred arc process. By adjusting plasma parameters, such as current, plasma gas flow, shielding gas flow, a number of coatings were formed on steel substrates. Structure of the coatings was investigated using X-ray diffractometry. Microstructure of cross-sectioned coatings was examined using scanning electron microscopy. Hardness of the coating was evaluated by means of the Vickers hardness tests. Wear tests were also performed on specimens to determine resistance to abrasive wear. Acquired results allowed estimating the influence of the deposition process parameters on structure and mechanical properties of the coatings.http://dx.doi.org/10.5755/j01.ms.17.2.482

75 FR 57846 - Airworthiness Directives; Robert E. Rust, Jr. Model DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk...

Science.gov (United States)

2010-09-23

... Aircraft Certification Office (ACO), 1701 Columbia Avenue, College Park, Georgia 30337; telephone: (404... Airworthiness Directives; Robert E. Rust, Jr. Model DeHavilland DH.C1 Chipmunk 21, DH.C1 Chipmunk 22, and DH.C1... the Docket Office (phone: 800-647-5527) is Document Management Facility, U.S. Department of...

Thermal interaction between WC-Co coating and steel substrate in process of HVOF spraying

International Nuclear Information System (INIS)

Guilemany, J.M.; Sobolev, V.V.; Nutting, J.; Dong, Z.; Calero, J.A.

1994-01-01

The WC-Co powders can be used to produce good adhesive and wear resistant HVOF thermal spray coatings on steel and light alloys substrates. In order to understand the properties of this kind of coating, the phases which are present in the coatings and structure changes during post heat treatments have been investigated. Although the coating properties depend very much on the structure developed in the substrate-coating interfacial region it has not been yet investigated in detail. The present study is devoted to the experimental and theoretical analysis of this interfacial region. The structure characterization has been performed mainly through the use of transmission electron microscopy. To provide a theoretical investigation a realistic prediction model of the process has been developed and on its base the mathematical simulation of the substrate-coating thermal interaction has been undertaken

Empirical ranking of a wide range of WC-Co grades in terms of their abrasion resistance measured by the ASTM standard B 611-85 test

CSIR Research Space (South Africa)

O'Quigley, DGF

1997-01-01

Full Text Available This paper reports the results of a comprehensive investigation into the abrasion resistance of WC-Co alloys, as measured by the ASTM Standard B 611-85 test. The alloys ranged from 3 to 50 wt% and from 0.6 to 5 mu-m average grain size. Careful...

East Weddell Sea echinoids from the JR275 expedition

Directory of Open Access Journals (Sweden)

Thomas Saucède

2015-05-01

Full Text Available Information regarding the echinoids in this dataset is based on the Agassiz Trawl (AGT and epibenthic sledge (EBS samples collected during the British Antarctic Survey cruise JR275 on the RRS James Clark Ross in the austral summer 2012. A total of 56 (1 at the South Orkneys and 55 in the Eastern Weddell Sea Agassiz Trawl and 18 (2 at the South Orkneys and 16 in the Eastern Weddell Sea epibenthic sledge deployments were performed at depths ranging from ~280 to ~2060 m. This presents a unique collection for the Antarctic benthic biodiversity assessment of an important group of benthic invertebrates. In total 487 specimens belonging to six families, 15 genera, and 22 morphospecies were collected. The species richness per station varied between one and six. Total species richness represents 27% of the 82 echinoid species ever recorded in the Southern Ocean (David et al. 2005b, Pierrat et al. 2012, Saucède et al. 2014. The Cidaridae (sub-family Ctenocidarinae and Schizasteridae are the two most speciose families in the dataset. They comprise seven and nine species respectively. This is illustrative of the overall pattern of echinoid diversity in the Southern Ocean where 65% of Antarctic species belong to the families Schizasteridae and Cidaridae (Pierrat et al. 2012.

Study of T L LiF: Mg,Ti (Model JR1152C) material for its use in the environmental monitoring; Estudio del material TL LiF: Mg, Ti (JR1152C) para su empleo en el monitoreo ambiental

Energy Technology Data Exchange (ETDEWEB)

Molina P, D.; Diaz B, E.; Prendes A, M. [Centro de Proteccion e Higiene de las Radiaciones, CPHR, Apdo. postal 6195, Habana 6, CP 10600, Ciudad Habana (Cuba)

1999-07-01

In order to evaluate the possibility to use the T L material of LiF: Mg,Ti (Model JR1152C) as environmental dosemeter it was realized its characterization of it according to the established criterion in the standard IEC-1066. The properties studied were: homogeneity of the lot, reproducibility, response linearity, detection threshold, auto irradiation, residual signal, response pride (fading) and angular dependence. The results prove the compliment of the IEC requirements and therefore the applicability of this dosemeter in the environmental monitoring. (Author)

Mechanical intermixing of components in (CoMoNi)-based systems and the formation of (CoMoNi)/WC nanocomposite layers on Ti sheets under ball collisions

Science.gov (United States)

Romankov, S.; Park, Y. C.; Shchetinin, I. V.

2017-11-01

Cobalt (Co), molybdenum (Mo), and nickel (Ni) components were simultaneously introduced onto titanium (Ti) surfaces from a composed target using ball collisions. Tungsten carbide (WC) balls were selected for processing as the source of a cemented carbide reinforcement phase. During processing, ball collisions continuously introduced components from the target and the grinding media onto the Ti surface and induced mechanical intermixing of the elements, resulting in formation of a complex nanocomposite structure onto the Ti surface. The as-fabricated microstructure consisted of uniformly dispersed WC particles embedded within an integrated metallic matrix composed of an amorphous phase with nanocrystalline grains. The phase composition of the alloyed layers, atomic reactions, and the matrix grain sizes depended on the combination of components introduced onto the Ti surface during milling. The as-fabricated layer exhibited a very high hardness compared to industrial metallic alloys and tool steel materials. This approach could be used for the manufacture of both cemented carbides and amorphous matrix composite layers.

Obituary: Raymond Edwin White Jr., 1933-2004

Science.gov (United States)

Liebert, James William

2004-12-01

Raymond E. White, Jr., died unexpectedly at his home, in the early morning hours of October 12, 2004. Death appears to have been caused by severe diabetic shock. He retired from the Department of Astronomy/Steward Observatory in July 1999 with the title of University Distinguished Professor, after serving on the faculty of this institution for over 35 years. He was born in Freeport, Illinois, on 6 May 1933, to Beatrice and Raymond E, Sr. -the latter being a career soldier in the US Army. Ray's early schooling took place in Illinois, New Jersey, Germany and Switzerland, following his father's assignments. He obtained a bachelors degree from the University of Illinois in 1955. Next Ray enlisted in the US Army, but quickly was enrolled in Officer Candidate School. He then served as lst Lt. in the US Army Corps of Engineers. Although military affairs remained a lifelong interest, and he was a member of the Company of Military Historians, Ray decided after three years to return to academia. He entered the astronomy PhD program at the University of Illinois in 1958. His PhD dissertation was supervised by Ivan R. King. Ray accepted a faculty position at the University of Arizona in 1964. First and foremost, Ray White was known at Arizona as an excellent teacher, revered by a large number of former students. When the astronomy major program was begun in 1967, Ray was one of three, original, major advisors. Over the next three decades, he was a leader at the University level in reforming the undergraduate program and courses. He was selected Outstanding University Faculty Member in April 1989 and he served as one of a handful of professors who are Faculty Fellows. These Fellows devote untold hundreds of hours as part-time residents at student dormitories, to give students a friendly face to address their problems. In 1995, Ray was among the first group of faculty to be recognized as University Distinguished Professors. In the year of his retirement, 1999, University

Modelizacion de la formación de recubrimientos de WC-Co por proyección HVOF sobre sustratos de cobre

Directory of Open Access Journals (Sweden)

Sobolev, V. V.

1997-10-01

Full Text Available Present paper deals with the mathematical simulation of the heat transfer between a WC-Co coating and a copper substrate during HVOF spraying. This modelling includes the investigation of temperature variation, coating solidification, melting and subsequent solidification in the substrate interfacial region and specific features of the substrate-coating thermal interaction. The results obtained are used for modelling of the development of the coating structure and adhesion during HVOF spraying of the WC-Co powder on a copper substrate. Two types of substrate were considered: smooth (polished and rough. Variations of solidification times, solidification velocity, thermal gradient and cooling velocity in the coating and substrate interfacial region are studied. Development of the amorphous and crystalline structures in the coating and of the crystalline structure in the substrate interfacial region is discussed. Behaviour of the crystal size and intercrystalline distance with respect to the thermal spray parameters and morphology of the substrate surface is analyzed. Optimal conditions for the formation of fine and dense crystalline structure are determined. Structural changes in the solid state of the substrate occurring because of heating and rapid cooling are considered. Mechanical and thermal mechanisms of development of the substrate-coating adhesion are discussed. Results obtained agree well with experimental data.

En el presente trabajo se ha investigado la simulación matemática de la transferencia de calor entre un recubrimiento de WC-Co y un sustrato de cobre durante la proyección HVOF. Este modelo incluye el estudio de la variación de termperatura, solidificación del recubrimiento, la fusión y posterior solidificación en la región interfacial del sustrato, y caracerísticas especiales de la interacción térmica sustrato- recubrimiento. Los resultados obtenidos han sido utilizados en la modelización del desarrollo de la

Multivariable modeling of pressure vessel and piping J-R data

International Nuclear Information System (INIS)

Eason, E.D.; Wright, J.E.; Nelson, E.E.

1991-05-01

Multivariable models were developed for predicting J-R curves from available data, such as material chemistry, radiation exposure, temperature, and Charpy V-notch energy. The present work involved collection of public test data, application of advanced pattern recognition tools, and calibration of improved multivariable models. Separate models were fitted for different material groups, including RPV welds, Linde 80 welds, RPV base metals, piping welds, piping base metals, and the combined database. Three different types of models were developed, involving different combinations of variables that might be available for applications: a Charpy model, a preirradiation Charpy model, and a copper-fluence model. In general, the best results were obtained with the preirradiation Charpy model. The copper-fluence model is recommended only if Charpy data are unavailable, and then only for Linde 80 welds. Relatively good fits were obtained, capable of predicting the values of J for pressure vessel steels to with a standard deviation of 13--18% over the range of test data. The models were qualified for predictive purposes by demonstrating their ability to predict validation data not used for fitting. 20 refs., 45 figs., 16 tabs

Mechanical characterization of cemented carbide WC-6Co (%wt) manufactured by SPS (Spark Plasma Sintering

International Nuclear Information System (INIS)

Boidi, G.; Tertuliano, A.J.; Machado, I.F.

2016-01-01

This work aimed to manufacture cemented carbide (WC-6%wtCo) obtained by SPS (Spark Plasma Sintering) process and to carry out the mechanical characterization by hardness and fracture toughness. The material was consolidated at 1100 deg C for different holding times (1 min, 5 min, 10 min), in order to evaluate the densification. A reference sample was also used to be compared to SPS. Optical and scanning electron microscopy were carried out to characterize the microstructural features of the samples and mechanical properties were obtained by hardness measurements (micro and macro) and instrumented indentation. The fracture toughness was calculated with the method of Palmqvist. Best results were found in the material sintered by SPS for 10 minutes of holding time, in which 97% of relative density and about 1600 HV_1_0 was reached. (author)

Effect of the sulphur atom on geometry and spectra of the biomolecule 2-thiouracil and in the WC base pair 2-thiouridine-adenosine. Influence of water in the first hydration shell.

Science.gov (United States)

Alcolea Palafox, M; Rastogi, V K; Singh, S P

2018-04-01

The effect of the sulphur atom on 2-thiouracil (2TU) and 2-thiouridine molecules, as compared with uracil and uridine molecules, respectively, was carried out in several environments. The predicted IR spectrum of 2TU in the isolated state was compared with that obtained for uracil molecule and with those reported experimentally in matrix isolation. Its crystal unit cell in the solid state was simulated through a tetramer form using DFT methods for the first time. The calculated Raman spectrum was compared to the experimental ones in the solid state. A linear scaling procedure was used for this task. The first hydration shell was simulated by explicit number of water molecules surrounding 2TU up to 30 and was compared with that obtained in uracil molecule. Water molecules 'distributed' around 2TU was preferred over that 'clustering', because it can better reproduce the hydration and their effects on different parameters of the molecular structure of 2TU and uracil. The total atomic charges and several calculated thermodynamic parameters were discussed. The effect of the sulphur atom on the Watson-Crick (WC) and reverse WC base pair uridine-adenosine was estimated, and the CP corrected interaction energies were calculated. 2-thiouridine has a weaker WC pair than that with uridine, although its slight higher dipole moment (μ) facilitates the interaction with the water molecules. Several helical parameters were determined.

Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part II: Cavitation Erosion

Directory of Open Access Journals (Sweden)

D. Kekes

2014-12-01

Full Text Available Composite coatings with five different proportions of WC-Co/Cr and NiCrFeBSiC components were deposited on stainless steel by HVOF spraying. Cavitation erosion tests were performed and the material removal micro-mechanisms were identified by SEM of both the eroded areas and the specimens’ cross-sections. Waves’ propagation and deflection at the weak interfaces within the coatings resulted in local tensile stresses perpendicular to the interface direction that eventually led to material removal. Such weak interfaces are the boundaries of the carbide particles with the metal binder within the same splat, those between splats along the same layer and those between successively deposited layers.

Machinability of Al-SiC metal matrix composites using WC, PCD and MCD inserts

Energy Technology Data Exchange (ETDEWEB)

Beristain, J.; Gonzalo, O.; Sanda, A.

2014-04-01

The aim of this work is the study of the machinability of aluminium-silicon carbide Metal Matrix Composites (MMC) in turning operations. The cutting tools used were hard metal (WC) with and without coating, different grades and geometries of Poly-Crystalline Diamond (PCD) and Mono-Crystalline Diamond (MCD). The work piece material was AMC225xe, composed of aluminium-copper alloy AA 2124 and 25% wt of SiC, being the size of the SiC particles around 3 {mu}m. Experiments were conducted at various cutting speeds and cutting parameters in facing finishing operations, measuring the surface roughness, cutting forces and tool wear. The worn surface of the cutting tool was examined by Scanning Electron Microscope (SEM). It was observed that the Built Up Edge (BUE) and stuck material is higher in the MCD tools than in the PCD tools. The BUE acts as a protective layer against abrasive wear of the tool. (Author)

Basil A. Pruitt Jr. MD and the US Army Institute for Surgical Research: Five Decades of Science, Clinical Care, Mentorship, and Leadership.

Science.gov (United States)

Stewart, Ronald M

2017-08-24

Over the past half century Dr. Basil A. Pruitt, Jr., a great citizen, surgeon, innovator, mentor and leader, transformed our world through his dogged commitment to science and service to humanity. Dr. Pruitt's contribution lives on in the work of the US Army Institute of Surgical Research and the surgeons, physicians and scientists he shaped and inspired.

Peer-Reviewed Research and the IEP: Implications of "Ridley School District v. M.R. and J.R. ex rel. E.R." (2012)

Science.gov (United States)

Yell, Mitchell L.; Katsiyannis, Antonis; Losinski, Mickey; Marshall, Kelsey

2016-01-01

This article examines a case out of the U.S. Court of Appeals for the Third Circuit: "Ridley School District v. M.R and J.R. ex rel. E.R." (2012). The case is the first circuit court case in which the Individuals with Disabilities Education Improvement Act requirement that special education services be based on peer-reviewed research…

Wear resistance of nano- and micro-crystalline diamond coatings onto WC-Co with Cr/CrN interlayers

Energy Technology Data Exchange (ETDEWEB)

Polini, Riccardo [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Roma Tor Vergata, Via della Ricerca Scientifica, 1, Rome, 00133 (Italy); Barletta, Massimiliano, E-mail: barletta@ing.uniroma2.i [Dipartimento di Ingegneria Meccanica, Universita di Roma Tor Vergata, Via del Politecnico, 1, Rome, 00133 (Italy); Cristofanilli, Giacomo [Dipartimento di Scienze e Tecnologie Chimiche, Universita di Roma Tor Vergata, Via della Ricerca Scientifica, 1, Rome, 00133 (Italy)

2010-12-30

Cr/CrN bi-layers have been used recently to promote the growth of high quality Hot Filament Chemical Vapour Deposition (HFCVD) diamond coatings onto Co-cemented tungsten carbide (WC-6 wt.%Co) substrates. In the present investigation, the influence of the crystalline size of the diamond coatings on their wear endurance is looked into. Nano- (NDC) and micro-crystalline Diamond Coatings (MDC) were deposited by HFCVD onto untreated and Fluidized Bed (FB) treated Cr/CrN interlayers. NDCs, characterized by a cauliflower-like morphology, showed improved wear resistance. However, the superimposition of NDCs onto Cr/CrN interlayers micro-corrugated by FB treatment was found to be the most promising choice, leading to the formation of highly adherent and wear resistant coatings.

Physical chemistry of WC-12 %Co coatings deposited by thermal spraying at different standoff distances

Energy Technology Data Exchange (ETDEWEB)

Afzal, Muhammad; Ahmed, Furqan; Anwar, Muhammad Yousaf; Ali, Liaqat; Ajmal, Muhammad [Univ. of Engineering and Technology, Metallurgical and Materials Engineering, Lahore (Pakistan); Khan, Aamer Nusair [Institute of Industrial and Control System, Rawalpindi (Pakistan)

2015-09-15

In the present research, WC-12 %Co cermet coatings were deposited on AISI-321 stainless steel substrate using air plasma spraying. During the deposition process, the standoff distance was varied from 80 to 130 mm with 10 mm increments. Other parameters such as current, voltage, time, carrier gas flow rate and powder feed rate etc. were kept constant. The objective was to study the effects of spraying distance on the microstructure of as-sprayed coatings. The microscopic analyses revealed that the band of spraying distance ranging from 90 to 100 mm was the threshold distance for optimum results, provided that all the other spraying parameters were kept constant. In this range of threshold distance, minimum percentages of porosity and defects were observed. Further, the formation of different phases, at six spraying distances, was studied using X-ray diffraction, and the phase analysis was correlated with hardness results.

TiC含量对WC-TiC-TaC硬质合金材料微观组织及力学性能的影响%Effects of TiC Content on Microstructure and Mechanical Property of WC-TiC-TaC Cemented Carbides

Institute of Scientific and Technical Information of China (English)

高姣姣; 姜龙凯; 宋金鹏; 梁国星; 安晶; 谢俊彩; 曹磊; 吕明

2017-01-01

本研究采用真空热压烧结技术,在1600℃下制备了WC-TiC-TaC硬质合金材料,研究了TiC含量对其微观组织及力学性能的影响.结果表明,随着TiC含量的增多,硬质合金材料的晶粒显著增大.当TiC的含量从10wt％ 增加到25wt％时,硬质合金材料的硬度逐渐增大,最高可达19.81 GPa,这是由于TiC的硬度高于基体WC的硬度;与此同时,硬质合金材料的抗弯强度和断裂韧度逐渐减小.当TiC的含量为10wt％时,材料的抗弯强度有最大值,其值为1147.24 MPa,这是由于在材料内部形成了均匀、细小的晶粒组织;在此含量下,复合材料的增韧机理为细晶增韧、裂纹偏转、裂纹分支、裂纹桥接和韧窝增韧,其断裂韧度有最大值,为14.60 MPa·m1/2.%WC-TiC-TaC cemented carbides were fabricated by hot-pressed sintering at 1600℃. Effects of TiC content on the microstructure and mechanical properties of these cemented carbides were investigated. It was found that when TiC content was increased from 10wt％ to 25wt％, both the average grain size and the Vickers hardness increased pro-gressively, but both the flexural strength and the fracture toughness decreased gradually. The increase of Vickers hard-ness was attributed to the increase of TiC content and the hardness of TiC was higher than that of WC. The value of the highest Vickers hardness was 19.81 GPa. This work also showed that the highest flexural strength (1147.24 MPa) was ascribed to the fine and homogeneous grains, and that the highest fracture toughness (14.60 MPa·m1/2) was due to the intensive coupled mechanism of the fine-grain toughening, crack deflection, crack branching, crack bridging, and toughness dimples.

Tribology study on TiB2+WSi2 composite against WC

Science.gov (United States)

Murthy, T. S. R. Ch.; Basha, M. M.; Sonber, J. K.; Singh, K.; Raju, K.; Sairam, K.; Nagaraj, A.; Majumdar, S.; Rao, G. V. S. Nageswara; Kain, Vivekanand

2018-04-01

Titanium diboride (TiB2) is one of the potential material for green energy applications such as neutron absorber in high temperature/advanced nuclear reactors, receiver materials for second generation concentrated solar power. We developed the process flow sheet for synthesis and consolidation of various series of TiB2 based materials in our laboratory. Amongst these, TiB2+WSi2 exhibited better sinterability and oxidation resistance properties. In the present work, tribology properties of TiB2+2.5%WSi2 composite was studied against WC-Co ball using different normal loads (5, 10 and 20 N) and frequencies (10, 15 Hz) under dry condition. Coefficient of friction (COF) and wear rate was measured at all test conditions. Wear mechanism was analyzed by microstructural characterization. It was found that COF is decreased from 0.46 to 0.36 with increasing load (5 to 20 N) at 15 Hz frequency; whereas at 10 Hz frequency COF is measured a constant average value of 0.49. The specific wear rate measured was minimum at 5 N load and 15 Hz frequency combination and was found to be 2.84×10-6 mm3/N m. The wear mechanisms identified during reciprocative sliding wear of composite were abrasion and surface tribo-oxidative reactions with delamination from tribo-zone.

Two-year follow-up results for Hip-Hop to Health Jr.: a randomized controlled trial for overweight prevention in preschool minority children.

Science.gov (United States)

Fitzgibbon, Marian L; Stolley, Melinda R; Schiffer, Linda; Van Horn, Linda; KauferChristoffel, Katherine; Dyer, Alan

2005-05-01

To assess the impact of a culturally proficient dietary/physical activity intervention on changes in body mass index (BMI) (kg/m 2 ). Randomized controlled trial (Hip-Hop to Health Jr.) conducted between September 1999 and June 2002 in 12 Head Start preschool programs in Chicago, Illinois. Intervention children had significantly smaller increases in BMI compared with control children at 1-year follow-up, 0.06 vs 0.59 kg/m 2 ; difference -0.53 kg/m 2 (95% CI -0.91 to -0.14), P = .01; and at 2-year follow-up, 0.54 vs 1.08 kg/m 2 ; difference -0.54 kg/m 2 (95% CI -0.98 to -0.10), P = .02, with adjustment for baseline age and BMI. The only significant difference between intervention and control children in food intake/physical activity was the Year 1 difference in percent of calories from saturated fat, 11.6% vs 12.8% ( P = .002). Hip-Hop to Health Jr. was effective in reducing subsequent increases in BMI in preschool children. This represents a promising approach to prevention of overweight among minority children in the preschool years.

Effects of hydrogen-charging on the properties of S235JR steel

Science.gov (United States)

Pietkun-Greber, Izabela

2017-10-01

The paper presents the test results of the S235JR steel susceptibility to damage under the influence of hydrogen. The test of mechanical properties was performed on the basis of a static stretch test of non-hydrogenated samples and after cathodic polarization. Electrochemical measurements for the assessment of corrosion resistance of non-hydrogenated and hydrogenated steels were carried out using open circuit potential measurement and registering of potentiodynamic polarization curves in a three-electrode measuring system. Hydrogenation was carried out for between 3 and 24 hours in a solution of 0.1 N sulfuric acid (VI) with the addition of 2 mg/dm 3 of arsenic oxide (III) at an electric current density of 10 mA/cm2. The hydrogen content in the steel before and after saturation with hydrogen was determined using the analyzer. Fracture samples after tensile test were observed using scanning electron microscope. The results of the research showed that as the hydrogen concentration in the examined steel increased (the lengthening of the saturation time), the deterioration of its mechanical and electrochemical properties occurred.

Corrosion behaviour of WC-Co based hardmetal in neutral chloride and acid sulphate media

Energy Technology Data Exchange (ETDEWEB)

Bozzini, B.; Serra, M.; Fanigliulo, A.; Bogani, F. [Lecce Univ. (Italy). Dipt. di Ingegneria dell' Innovazione; Gaudenzi, G.P. de [Harditalia s.r.l. (OMCD Group), Genova (Italy)

2002-05-01

A comparative study of the corrosion behaviour of WC-Co based hardmetals with Ni and Cr{sub 3}C{sub 2} additions is carried out. The aggressive environments are neutral and acidic aerated aqueous solutions of NaCl and H{sub 2}SO{sub 4}. This study is based on electrochemical (linear sweep voltammery), compositional (surface EDX analyses, AAS analyses of attack solutions), structural (XRD) and morphological (SEM) investigations. Electrochemical figures of merit were computed from linear sweep voltammograms in order to rank the corrosion behaviour close to free-immersion conditions in the studied environments and with presence of oxidising agents. EDX and XRD analyses allow to accurately characterise the penetration depth of the attack as well as the preferential dissolution of the constituents. Binders containing Ni show a significantly improved corrosion resistance in the studied systems. The amount of Ni in the binder is the single most important factor affecting corrosion performance. Cr{sub 3}C{sub 2} additions to hardmetals with lower-Ni binders cannot balance the effect of Ni, but give an improved resistance in neutral chloride-containing solutions. (orig.)

~ i t i d e r m a t o ~ h ~ t i c Activities of Nine (9) Essential Oils J.R. ...

African Journals Online (AJOL)

i t i d e r m a t o ~ h ~ t i c Activities of Nine (9) Essential Oils. J.R. KUIATE", S.P. KUATE'.~, N.E. KEMADJOU~, S. DJOKOUA~, F. ZIFACK~ AND J. ~. 0. ~. 0. ~. I Department of Biochemistry, FS, University of Dschang, P.O. Box 67 Dschang, Cameroon. 2~epartment of Biochemistry, FS, University of Yaoundt!, P.O. Box 812 ...

Lynn White Jr. and the greening-of-religion hypothesis.

Science.gov (United States)

Taylor, Bron; Van Wieren, Gretel; Zaleha, Bernard Daley

2016-10-01

Lynn White Jr.'s "The Historical Roots of Our Ecologic Crisis," which was published in Science in 1967, has played a critical role in precipitating interdisciplinary environmental studies. Although White advances a multifaceted argument, most respondents focus on his claim that the Judeo-Christian tradition, especially Christianity, has promoted anthropocentric attitudes and environmentally destructive behaviors. Decades later, some scholars argue contrarily that Christianity in particular and the world's predominant religions in general are becoming more environmentally friendly, known as the greening-of-religion hypothesis. To test these claims, we conducted a comprehensive review of over 700 articles-historical, qualitative, and quantitative-that are pertinent to them. Although definitive conclusions are difficult, we identified many themes and dynamics that hinder environmental understanding and mobilization, including conservative theological orientations and beliefs about the role of divine agency in preventing or promoting natural events, whether the religion is an Abrahamic tradition or originated in Asia. On balance, we found the thrust of White's thesis is supported, whereas the greening-of-religion hypothesis is not. We also found that indigenous traditions often foster proenvironmental perceptions. This finding suggests that indigenous traditions may be more likely to be proenvironmental than other religious systems and that some nature-based cosmologies and value systems function similarly. Although we conclude White's thesis and subsequent claims are largely born out, additional research is needed to better understand under what circumstances and communication strategies religious or other individuals and groups may be more effectively mobilized to respond to contemporary environmental challenges. © 2016 Society for Conservation Biology.

The Applicability of Taylor’s Model to the Drilling of CFRP Using Uncoated WC-Co Tools: The Influence of Cutting Speed on Tool Wear

OpenAIRE

Merino Perez, J.L.; Merson, E.; Ayvar-Soberanis, S.; Hodzic, A.

2014-01-01

This work investigates the applicability of Taylor’s model on the drilling of CFRP using uncoated WC-Co tools, by assessing the influence of cutting speed (Vc) on tool wear. Two different resins, possessing low and high glass transition temperatures (Tg), and two different reinforcements, high strength and high modulus woven fabrics, were combined into three different systems. Flank wear rate gradient exhibited to be more reinforcement dependent, while the actual flank wear rate showed to be ...

The Son's Fault: Martin Luther King, Jr.'s Search for and Recovery of Sonship.

Science.gov (United States)

Hinds, Jay-Paul

2018-04-01

This article examines the role of sonship in the psychological and spiritual development of men. In using the methodology of psychobiography, I explore the life history of Martin Luther King, Jr. to analyze his search for and recovery of sonship. I propose that sonship helps men rebel against and, in the end, overcome the feelings of inadequacy that are experienced in their struggles to achieve manhood, particularly within the father-son dyad. The scholarship of pastoral theologian Donald Capps is instructive in this regard, in that he suggests that sons should be allowed to search for a male figure, a father-substitute, who can affirm, not disdain or reject, this state of sonship. In the end, what is often viewed as a negative act of regression-i.e., the recovery of and return to sonship-is recognized instead as a positive one that assists a man in his journey toward wholeness.

Study of T L LiF: Mg,Ti (Model JR1152C) material for its use in the environmental monitoring

International Nuclear Information System (INIS)

Molina P, D.; Diaz B, E.; Prendes A, M.

1999-01-01

In order to evaluate the possibility to use the T L material of LiF: Mg,Ti (Model JR1152C) as environmental dosemeter it was realized its characterization of it according to the established criterion in the standard IEC-1066. The properties studied were: homogeneity of the lot, reproducibility, response linearity, detection threshold, auto irradiation, residual signal, response pride (fading) and angular dependence. The results prove the compliment of the IEC requirements and therefore the applicability of this dosemeter in the environmental monitoring. (Author)

Estudio por emisión acústica del comportamiento a flexión de recubrimientos WC-Co obtenidos por plasma atmosférico

Directory of Open Access Journals (Sweden)

Segovia, F.

2007-12-01

Full Text Available Plasma sprayed cermet coatings WC-Co are used in a wide range of industrial applications, mainly due to their wear resistance even in corrosive environments. The objective of this work is to analyze mechanical response of hard metal coatings by means of three- and four-points bend tests applying acoustic emission technique to determine failure critical strength. It has been observed the effect of supported charge level in structural damage by means of optical microscopy and scanning electron microscopy. Acoustic emission has allowed us to relate damage level to stresses level and then to understand coatings failure mechanism.

Los recubrimientos de cermet WC-Co proyectados por plasma se utilizan en un amplio rango de aplicaciones industriales, principalmente por su resistencia al desgaste, incluso en medio corrosivo. El objetivo de este trabajo es analizar la respuesta mecánica de los recubrimientos de metal duro mediante ensayos de flexión a 3 y 4 puntos aplicando el método de emisión acústica para determinar las tensiones críticas de fallo. Se ha observado el efecto del nivel de carga soportado en el dañado estructural mediante microscopia óptica y electrónica de barrido. La emisión acústica ha permitido relacionar el grado de dañado con el nivel de tensiones y, así, entender el mecanismo de fallo de los recubrimientos.

Comportamiento a desgaste de recubrimientos de WC proyectados por plasma a partir de polvos micro y nanoestructurados

Directory of Open Access Journals (Sweden)

Salvador, M. D.

2008-06-01

Full Text Available The aim of the present work is the study of wear behaviour of different WC coatings deposited on stainless steel substrate by means of atmospheric plasma spraying (APS. Two types of WC commercial powders, with different metal binder (12% Cobalt and 10% Nickel have been deposited in order to analyse the influence of the metal matrix and thickness of the coating in tribological properties.The microstructure of the depositions was characterized using scanning electron microscopy (SEM and X-ray diffraction analysis (XRD. On the other hand, tribology characterization of the coatings was made by pin-on-disk wear tests against alumina (2400HV and silicon nitride (1600HV ceramic balls, without lubrication. Wear rates and friction coefficient evolution have been calculated. Finally, wear tracks and wear debris have been analysed with the help of SEM.The results of each pair of tested materials show different mechanisms of wear related to the nature of the ball that has been used, obtaining higher wear rates with silicone nitride ball..In a second phase of the study, in order to examine the influence of the initial particle size on the wear properties of the coatings, cobalt based coatings have been analysed with different initial particle size (micrometric and nanometric particles.Results show that nanostructured coatings have higher wear resistance than microstrutured ones for high loads. However for low loads, behaviour is similar in spite of the microstructural differences appreciated.

El objetivo de este trabajo es estudiar el comportamiento a desgaste de distintos recubrimientos de WC sobre acero inoxidable mediante proyección por plasma atmosférico. Se proyectan dos tipos de polvos comerciales con base cobalto (12 % y níquel (10 %, con el objeto de analizar la influencia de la matriz e incluso del espesor del recubrimiento. Los recubrimientos obtenidos se caracterizan microestructuralmente por microscopía electrónica de barrido y

Performance of Asphalt Concrete Wearing Course (AC-WC) Utilizing Reclaimed Asphalt Pavement from Cold Milling Bound with 80/100 Pen Asphalt

Science.gov (United States)

Thanya, I. N. A.; Suweda, I. W.; Putra, G. K.

2018-03-01

Demands on natural aggregate materials for road pavement can be reduced by utilizing reclaimed asphalt pavement (RAP). This research was aimed at evaluating the performance of AC-WC mixture using RAP materials from cold milling, bound with 80/100 pen asphalt. The RAP aggregate gradation was adjusted by adding the required amount of natural aggregates to meet the specification in Indonesia. The RAP and added aggregates were hotmixed and compacted with Marshall hummer at 2×75 blows. The asphalt content were varied. It was found that the optimum asphalt content was 6.05 % with the following Marshall characteristics: stability 1237.08 kg; flow 3.36 mm; Marshall quotient 324,73kg/mm; void in mix (VIM) 3,360%; void in mineral aggregate (VMA) 15.103; and void filled with bitumen (VFB) 77.759% and residual stability 91.04; all met the Indonesian specification. The cantabro abration loss (CAL) at 30°C was 9,02%. The indirect tensile stiffness modulus (ITSM) at 20 °C was 7961.4 MPa; dynamic creep with 100 kPa pressure at 40°C gave slope 0.0112 microsstrain/pulse which is suitable for heavy load traffic. The fatigue test results was obtained at increased stress level, i.e. at 900, 1100, and 1300 kPa. Based on the equation derived from the fatigue strain and repeated loading relationship, at 100 microstrain (με) the repeated load was 434,661.58 times, and at one million (106) repeated loading, the samples could withstand strain of 92,38 microstrain. The performance of the samples were overall better than AC-WC mixture using virgin aggregates bound with 60/70 pen asphalt.

General Charles F. Bolden, Jr. and Professor Claude Nicollier reunite during visit to CERN

CERN Multimedia

Jordan Juras

2011-01-01

Thursday 23 June, CERN saw an unlikely and much savoured meeting between two old colleagues and friends: General Charles F. Bolden, Jr. and Professor Claude Nicollier.   Bolden and Nicollier were separately invited to CERN for different reasons - Charles Bolden had been invited by Professor Samuel Ting to visit the newly built and now fully operational Payload Operation and Control Centre of the AMS collaboration and Claude Nicollier had been invited by the Theory Department to give a colloquium. They were delightfully surprised when they met at the entrance of the main building. Bolden and Nicollier served together in the Space Shuttle Program and were trained by NASA during the 1980’s where they became close friends. On 24 April, 1990, Bolden piloted the Space Shuttle Discovery into orbit with the Hubble telescope in the payload bay. Though Nicollier did not accompany Bolden during the Hubble launch, he did return to the telescope 3 years later on board the Space Shuttle Ende...

Periodization of the urban interventions: a review of ratings from “Vargas & Castilho”, “Boyer” and “Simões Jr.”

Directory of Open Access Journals (Sweden)

Geise Brizotti Pasquotto

2010-09-01

Full Text Available The present paper aims to compare the periods proposed by three authors “Vargas e Castilho” (2006, “Boyer” (1998 and “Simões Jr.” (1994. They did it to identify four significant moments of intervention in urban space from the period of modernity. It is noteworthy that, in this comparison, the most important thing is not to define a concept, but understanding the process and the paradigms that underpin each of these interventions.

On modeling the CNC end milling characteristics of Al-7075/WC powder metallurgy composites

Science.gov (United States)

Hanuman, N. S. V. N.; Rao, P. Gangadhara; Kumar, B. Sudheer; Karthik, N.

2017-07-01

Surface finish and material removal rate are two important factors in the manufacturing which affect acceptability of the product which in turn reflects on the profitability of the organization. The worth of the production setup to produce the components with high material removal rate (MRR) without sacrificing the surface requirements can play vital role in sustainability and profitability of the organization. In this paper, the effect of process parameters on metal removal rate and surface roughness has been investigated in milling of Al7075-MMC with WC as reinforcement element. Cutting speed, feed and depth of cut have been taken as input factors in three level response surface methodologies used for experimentation. Mathematical models have been developed using response surface methodology to predict surface finish, and metal removal rate in term of machining parameters. Depth of cut and feed rate are found to be a dominant parameter for surface roughness; whereas feed rate mainly affects the metal removal rate. The results of mathematical models have been compared with the experimental and found to be in good agreement. The results of predicted model can be used in selection of process parameters to insure desired quality and improved productivity.

Os dilemas do marxismo latino-americano nas obras de Caio Prado Jr. e José Carlos Mariátegui

OpenAIRE

Kaysel, André

2012-01-01

O objetivo deste artigo é comparar a relação entre o marxismo e a questão nacional nas obras do historiador brasileiro Caio Prado Jr. e do jornalista e militante peruano José Carlos Mariátegui. Parto da hipótese de que ambos compartilham uma leitura análoga da questão nacional, entendida como formação inconclusa da nação, obstaculizada pela persistência do legado colonial. Para tanto, discuto as proximidades e as discrepâncias entre os dois autores por meio de um cotejo de suas obras em torno...

Hip-Hop to Health Jr. Randomized Effectiveness Trial

Science.gov (United States)

Kong, Angela; Buscemi, Joanna; Stolley, Melinda R.; Schiffer, Linda A.; Kim, Yoonsang; Braunschweig, Carol L.; Gomez-Perez, Sandra L.; Blumstein, Lara B.; Van Horn, Linda; Dyer, Alan R.; Fitzgibbon, Marian L.

2015-01-01

Introduction The preschool years provide a unique window of opportunity to intervene on obesity-related lifestyle risk factors during the formative years of a child’s life. The purpose of this study was to assess the impact of a preschool-based obesity prevention effectiveness trial at 1-year follow-up. Design RCT. Settings/participants Primarily African American children (aged 3–5 years, N=618) attending Head Start preschool programs administered by Chicago Public Schools. Methods Eighteen preschools were randomly assigned in 2007–2008 to receive either: (1) a 14-week teacher-delivered intervention focused on healthy lifestyle behaviors; or (2) a 14-week teacher-delivered general health curriculum (control group). Main outcome measures The primary outcome, BMI, was measured at baseline, post-intervention, and 1-year follow-up. Diet and screen time behaviors were also assessed at these time points. Multilevel mixed effects models were used to test for between-group differences. Data were analyzed in 2014. Results Significant between-group differences were observed in diet, but not in BMI z-score or screen time at 1-year follow-up. Diet differences favored the intervention arm over controls in overall diet quality (p=0.02) and in subcomponents of diet quality, as measured by the Healthy Eating Index-2005, and in fruit intake (servings/day, excludes juice) (p=0.02). Diet quality worsened more among controls than the intervention group at 1-year follow-up. Conclusions The adaptation of Hip-Hop to Health Jr. produced modest benefits in diet quality, but did not significantly impact weight gain trajectory. Not unlike other effectiveness trials, this real-world version delivered by Head Start teachers produced fewer benefits than the more rigorous efficacy trial. It is important to understand and build upon the lessons learned from these types of trials so that we can design, implement, and disseminate successful evidence-based programs more widely and effectively

Characterization of microstructure and surface properties of hybrid coatings of WC-CoCr prepared by laser heat treatment and high velocity oxygen fuel spraying

International Nuclear Information System (INIS)

Zhang Shihong; Cho, Tong-Yul; Yoon, Jae-Hong; Fang, Wei; Song, Ki-O; Li Mingxi; Joo, Yun-Kon; Lee, Chan Gyu

2008-01-01

The microstructure and microhardness of high velocity oxygen fuel-sprayed WC-CoCr coatings were comparatively studied both before and after laser heat treatment of the coatings. Optical microscopy, scanning electron microscopy, X-ray diffraction and microhardness testing were applied to investigate the microstructure, phase composition, porosity and microhardness. The results indicate that WC is still present, and W 2 C has appeared, while neither cobalt nor σ-CrCo is detectable. Co 4 W 2 C has appeared in the high velocity oxygen fuel-sprayed coating after laser heat treatment as compared to the coating before laser treatment. The relative content of the W 2 C has not increased with laser treatment, but the laser treatment has essentially eliminated the porosity almost entirely, providing a more homogeneous and densified microstructure. The laser heat treatment has effected the formation of a denser compact coating on the substrate. After laser heat treatment, the thickness of the coating has decreased from 300 μm to 225 μm. This corresponds to an average porosity in the high velocity oxygen fuel-sprayed coating that is approximately five times greater than that in the subsequently laser heat-treated coating. The laser treatment has also resulted in an increased hardness of the coating near the surface, where the average value increased from Hv 0.2 = 1262.4 in the coating before laser heat treatment to Hv 0.2 = 1818.7 after laser heat treatment

Study of the sintering behavior of fine, ultrafine and nanocrystalline WC-CO mixtures obtained by high energy milling; Estudio del comportamiento durante la sinterizacion de mezclas WC-Co finas, ultrafinas y nanocristalinas obtenidas por molienda de alta energia

Energy Technology Data Exchange (ETDEWEB)

Salvador, M. D.; Bonache, V.; Amigo, V.; Busquets, D.

2008-07-01

In this work the sintering behaviour of fine, ultrafine and nanocrystalline WC-12Co mixtures obtained by high energy milling, as well commercial nano powders, have been studied, in order to evaluate the effect of the particle size and the powder processing, in the densification, microstructural development and mechanical properties of the final product. The consolidation of the mixtures has been made by uniaxial pressing and sintering in vacuum, and by hot isostatic pressing. The sintered materials have been evaluated by measures of density, hardness and indentation fracture toughness, and micro structurally characterized by optical microscopy and scanning and transmission electronic microscopy (SEM and TEM). The results show the improvements in resistant behaviour of the materials obtained from nanocrystalline powders, in spite of the grain growth experienced during the sintering. The best results were obtained for the milling nanocrystalline material, which presents values of hardness higher than 180 HV. (Author) 46 refs.

Phenolic polyketides from the co-cultivation of marine-derived Penicillium sp. WC-29-5 and Streptomyces fradiae 007.

Science.gov (United States)

Wang, Yi; Wang, Liping; Zhuang, Yibin; Kong, Fandong; Zhang, Cuixian; Zhu, Weiming

2014-04-04

Penicillium sp. WC-29-5 was co-cultured with Streptomyces fradiae 007 to produce five natural products (1-3, 4a and 4b) that were isolated and characterized by spectroscopic analysis. Interestingly, these compounds were found to be different from those produced in discrete fungal and bacterial controls. Among these compounds, the absolute configurations of compounds 4a and 4b were determined for the first time by X-ray single crystal diffraction experiments and electronic circular dichroism (ECD) calculations. An evaluation of the cytotoxic activities of these compounds revealed that 4b was moderately cytotoxic towards HL-60 and H1975 tumor cells with IC₅₀ values of 3.73 and 5.73 µM, respectively, whereas compound 4a was only moderately cytotoxic towards H1975 cells with an IC₅₀ value of 3.97 µM.

The LVIS Jr. microstent to assist coil embolization of wide-neck intracranial aneurysms: clinical study to assess safety and efficacy

International Nuclear Information System (INIS)

Moehlenbruch, M.; Herweh, C.; Behrens, L.; Jestaedt, L.; Bendszus, M.; Pham, M.; Amiri, H.; Ringleb, P.A.

2014-01-01

This study was aimed to assess clinical safety and efficacy of the LVIS Jr. microstent in stent-assisted coil embolization of wide-neck intracranial aneurysms. IRB approved single-center interventional clinical study in 22 patients (10 females, 12 males, mean age 55, age range 33-74 years) for the endovascular treatment of wide-neck aneurysms. After obtaining informed consent, patients were included according to the following criteria: aneurysm fundus-to-neck ratio 4 mm, and a parent vessel diameter of ≤3.5 mm. Primary end point for clinical safety was absence of death, absence of major or minor stroke, and absence of transient ischemic attack. Primary end point for treatment efficacy was complete angiographic occlusion according to the Raymond-Roy Occlusion Classification (RROC) immediately after the procedure and at follow-up after 3 and 6 months on magnetic resonance imaging (MRI). In 20/22 (91 %) of patients, the primary end point of safety was reached; in the two remaining patients, transient ischemic attack, but no permanent deficit was observed; in 16/22 (73 %), efficient occlusion (RROC1) was reached, and in 6/22 (27 %), a residual neck remained (RROC2). Single [seven with antegrade, two in crossover configuration, and four with ''first-balloon-then-stent'' (FBTS) technique] or double-stent (eight patients with Y configuration and one patient with X configuration) deployment was technically successful in all cases. Deployment of the LVIS Jr. microstent in various single- or double-stent configurations is safe and effective to assist the treatment of intracranial wide-neck aneurysms. (orig.)

Comparison of Body Mass Index (BMI, Body Adiposity Index (BAI, Waist Circumference (WC, Waist-To-Hip Ratio (WHR and Waist-To-Height Ratio (WHtR as predictors of cardiovascular disease risk factors in an adult population in Singapore.

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Benjamin Chih Chiang Lam

Full Text Available Excess adiposity is associated with cardiovascular disease (CVD risk factors such as hypertension, diabetes mellitus and dyslipidemia. Amongst the various measures of adiposity, the best one to help predict these risk factors remains contentious. A novel index of adiposity, the Body Adiposity Index (BAI was proposed in 2011, and has not been extensively studied in all populations. Therefore, the purpose of this study is to compare the relationship between Body Mass Index (BMI, Waist Circumference (WC, Waist-to-Hip Ratio (WHR, Waist-to-Height Ratio (WHtR, Body Adiposity Index (BAI and CVD risk factors in the local adult population.This is a cross sectional study involving 1,891 subjects (Chinese 59.1% Malay 22.2%, Indian 18.7%, aged 21-74 years, based on an employee health screening (2012 undertaken at a hospital in Singapore. Anthropometric indices and CVD risk factor variables were measured, and Spearman correlation, Receiver Operating Characteristic (ROC curves and multiple logistic regressions were used. BAI consistently had the lower correlation, area under ROC and odd ratio values when compared with BMI, WC and WHtR, although differences were often small with overlapping 95% confidence intervals. After adjusting for BMI, BAI did not further increase the odds of CVD risk factors, unlike WC and WHtR (for all except hypertension and low high density lipoprotein cholesterol. When subjects with the various CVD risk factors were grouped according to established cut-offs, a BMI of ≥23.0 kg/m2 and/or WHtR ≥0.5 identified the highest proportion for all the CVD risk factors in both genders, even higher than a combination of BMI and WC.BAI may function as a measure of overall adiposity but it is unlikely to be better than BMI. A combination of BMI and WHtR could have the best clinical utility in identifying patients with CVD risk factors in an adult population in Singapore.

Extending the Technological, Discursive, and Rhetorical Horizons of Academic Research Libraries' Information Architectures: An Analysis of North Carolina State University's James B. Hunt Jr. Library

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Carr, Patrick L.

2017-01-01

This dissertation analyzes how North Carolina State University's (NCSU) James B. Hunt Jr. Library extends the ways in which the information architectures of academic research libraries can function as a technology, as discourse, and as rhetoric. The starting point for the analysis is the libraries of antiquity, which functioned technologically as…

The Microcosm within: An interview with William B. Miller, Jr., on the Extended Hologenome theory of evolution.

Science.gov (United States)

Hunt, Tam

2015-01-01

There is a singular unifying reality underlying every biologic interaction on our planet. In immunology, that which does not kill you makes you different. -William B. Miller, Jr. We are experiencing a revolution in our understanding of inner space on a par with our exponentially increasing understanding of outer space. In biology, we are learning that the genetic and epigenetic complexity within organisms is far deeper than suspected. This is a key theme in William B. Miller Jr.'s book, The Microcosm Within: Evolution and Extinction in the Hologenome. We are learning also that a focus on the human genome alone is misleading when it comes to who we really are as biological entities, and in terms of how we and other creatures have evolved. Rather than being defined by the human genome alone, we are instead defined by the "hologenome," the sum of the human genome and the far larger genetic endowment of the microbiome and symbiotic communities that reside within and around us. Miller is a medical doctor previously in private practice in Pennsylvania and Phoenix, Arizona. This book is his first foray into evolutionary theory. His book could have been titled "The Origin of Variation" because this is his primary focus. He accepts that natural selection plays a role in evolution, but he demotes this mechanism to a less important role than the Modern Synthesis suggests. His main gripe, however, concerns random variation. He argues that random variation is unable to explain the origin and evolution of biological forms that we see in the world around us and in the historical record. Miller suggests that, rather than random variation as the engine of novelty, there is a creative impulse at the heart of cellular life, and even at the level of the genetic aggregate, that generates novelty on a regular basis. I probe this assertion in the interview below. He also highlights the strong role of "exogenous genetic assault" in variation and in his immunological model of evolution.

Statistical Optimization of Reactive Plasma Cladding to Synthesize a WC-Reinforced Fe-Based Alloy Coating

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Wang, Miqi; Zhou, Zehua; Wu, Lintao; Ding, Ying; Xu, Feilong; Wang, Zehua

2018-04-01

A new compound Fe-W-C powder for reactive plasma cladding was fabricated by precursor carbonization process using sucrose as a precursor. The application of quadratic general rotary unitized design was highlighted to develop a mathematical model to predict and accomplish the desired surface hardness of plasma-cladded coating. The microstructure and microhardness of the coating with optimal parameters were also investigated. According to the developed empirical model, the optimal process parameters were determined as follows: 1.4 for C/W atomic ratio, 20 wt.% for W content, 130 A for scanning current and 100 mm/min (1.67 mm/s) for scanning rate. The confidence level of the model was 99% according to the results of the F-test and lack-of-fit test. Microstructural study showed that the dendritic structure was comprised of a mechanical mixture of α-Fe and carbides, while the interdendritic structure was a eutectic of α-Fe and carbides in the composite coating with optimal parameters. WC phase generation can be confirmed from the XRD pattern. Due to good preparation parameters, the average microhardness of cladded coating can reach 1120 HV0.1, which was four times the substrate microhardness.

High hardness-high toughness WC-20Co nanocomposites: Effect of VC variation and sintering temperature

International Nuclear Information System (INIS)

Kumar, Devender; Singh, K.

2016-01-01

WC-Co nanocomposites with variable VC content are synthesized by liquid phase sintering at two different temperatures. The as synthesized samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and optical microscope. The mechanical properties are obtained by Vickers indentation method. The high content of VC, lead to high porosity when sintering temperature is increased from 1350 to 1400 °C. The relative density of all the samples is more than 95%. Microstructure reveals that agglomeration of W-Co-C and V-W-C increases at 1400 °C, which generates layered interfaces in radial direction and hence the material inhomogeneity. XRD pattern shows that the formation of η phase increases at 1400 °C, which is responsible to decrease the fracture toughness of the present samples. The average particle size of 102 nm, highest hardness of 1870.6 kgf/mm"2 with fracture toughness of 14.4 MN/mm"3"/"2 is observed in sample having 7.5 wt% VC, sintered at 1350 °C for one minute. This combination shows the highest hardness and reasonably high toughness as compared to conventionally sintered materials reported so far.

XMM-Newton X-ray observations of γ2 Velorum (WC8 + O7.5III)

International Nuclear Information System (INIS)

Raassen, A.J.J.; Mewe, R.; Hucht, K.A. van der; Schmutz, W.; Schild, H.; Dumm, T.; Guedel, M.; Audard, M.; Leutenegger, M.A.; Skinner, S.L.

2004-01-01

The spectrum of the binary system γ 2 Velorum (WC8 + O7.5III) has been observed with RGS and EPIC-MOS aboard XMM-Newton. The system shows a 'high state' when the O-star is between the Wolf-Rayet star and the observer (near periastron) and a 'low state' when most of the spectrum is absorbed by the dense stellar wind of the Wolf-Rayet star (near apastron). The spectrum has been model-led by a 4-T plasma, using SPEX. The absorption affects the hot temperature component (kT = 1.5 keV) that is formed by the collision of the Wolf-Rayet wind and the O-star wind, and the second hot component (kT 0.65 keV) for which the origin is still unclear. Part of the spectrum is not sensitive to the absorption by the stellar wind. This concerns a low-temperature component (kT = 0.23 keV) and features that are produced by plasma that has been photoionized by X-ray radiation from the hot component. In the RGS spectrum features of Radiative Recombination Continua (RRC) of C VI and C V of this photoionized plasma are detected

Phenolic Polyketides from the Co-Cultivation of Marine-Derived Penicillium sp. WC-29-5 and Streptomyces fradiae 007

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Yi Wang

2014-04-01

Full Text Available Penicillium sp. WC-29-5 was co-cultured with Streptomyces fradiae 007 to produce five natural products (1–3, 4a and 4b that were isolated and characterized by spectroscopic analysis. Interestingly, these compounds were found to be different from those produced in discrete fungal and bacterial controls. Among these compounds, the absolute configurations of compounds 4a and 4b were determined for the first time by X-ray single crystal diffraction experiments and electronic circular dichroism (ECD calculations. An evaluation of the cytotoxic activities of these compounds revealed that 4b was moderately cytotoxic towards HL-60 and H1975 tumor cells with IC50 values of 3.73 and 5.73 µM, respectively, whereas compound 4a was only moderately cytotoxic towards H1975 cells with an IC50 value of 3.97 µM.

Hip-Hop to Health Jr. Obesity Prevention Effectiveness Trial: postintervention results.

Science.gov (United States)

Fitzgibbon, Marian L; Stolley, Melinda R; Schiffer, Linda A; Braunschweig, Carol L; Gomez, Sandra L; Van Horn, Linda; Dyer, Alan R

2011-05-01

The preschool years offer an opportunity to interrupt the trajectory toward obesity in black children. The Hip-Hop to Health Jr. Obesity Prevention Effectiveness Trial was a group-randomized controlled trial assessing the feasibility and effectiveness of a teacher-delivered weight control intervention for black preschool children. The 618 participating children were enrolled in 18 schools administered by the Chicago Public Schools. Children enrolled in the nine schools randomized to the intervention group received a 14-week weight control intervention delivered by their classroom teachers. Children in the nine control schools received a general health intervention. Height and weight, physical activity, screen time, and diet data were collected at baseline and postintervention. At postintervention, children in the intervention schools engaged in more moderate-to-vigorous physical activity (MVPA) than children in the control schools (difference between adjusted group means = 7.46 min/day, P = 0.02). Also, children in the intervention group had less total screen time (-27.8 min/day, P = 0.05). There were no significant differences in BMI, BMI Z score, or dietary intake. It is feasible to adapt an obesity prevention program to be taught by classroom teachers. The intervention showed positive influences on physical activity and screen time, but not on diet. Measuring diet and physical activity in preschool children remains a challenge, and interventions delivered by classroom teachers require both intensive initial training and ongoing individualized supervision.

New WC-Cu thermal barriers for fusion applications: High temperature mechanical behaviour

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Tejado, E.; Dias, M.; Correia, J. B.; Palacios, T.; Carvalho, P. A.; Alves, E.; Pastor, J. Y.

2018-01-01

The combination of tungsten carbide and copper as a thermal barrier could effectively reduce the thermal mismatch between tungsten and copper alloy, which are proposed as base armour and heat sink, respectively, in the divertor of future fusion reactors. Furthermore, since the optimum operating temperature windows for these divertor materials do not overlap, a compatible thermal barrier interlayer between them is required to guarantee a smooth thermal transition, which in addition may mitigate radiation damage. The aim of this work is to study the thermo-mechanical properties of WC-Cu cermets fabricated by hot pressing. Focus is placed on the temperature effect and composition dependence, as the volume fraction of copper varies from 25 to 50 and 75 vol%. To explore this behaviour, fracture experiments are performed within a temperature range from room temperature to 800 °C under vacuum. In addition, elastic modulus and thermal expansion coefficient are estimated from these tests. Results reveal a strong dependence of the performance on temperature and on the volume fraction of copper and, surprisingly, a slight percent of Cu (25 vol%) can effectively reduce the large difference in thermal expansion between tungsten and copper alloy, which is a critical point for in service applications. The thermal performance of these materials, together with their mechanical properties could indeed reduce the heat transfer from the PFM to the underlying element while supporting the high thermal stresses of the joint. Thus, the presence of these cermets could allow the reactor to operate above the ductile to brittle transition temperature of tungsten, without compromising the underlying materials.

Obituary: Ernest Hurst Cherrington, Jr., 1909-1996

Science.gov (United States)

Osterbrock, Donald E.

2003-12-01

Ernest H. Cherrington, Jr., a long-time member of the AAS, died in San Jose, California on 13 July 1996, following a long illness. He had a short but active career as a research astronomer at Perkins Observatory at Ohio Wesleyan University in Delaware, Ohio before World War II, in which he served as an officer in the Army Air Force. After the war ended he turned to full-time teaching and administration at the University of Akron, and then at Hood College in Frederick, Maryland. Ernest was born on 10 September 1909 in Westerville, Ohio, where his father, Ernest H. Cherrington, Sr., was a leader in the temperance movement and publisher of "American Issue", a Prohibitionist magazine. Ernest Jr.'s mother, Betty Clifford (née Denny) Cherrington, was a homemaker. He was an outstanding student in high school and at Ohio Wesleyan University, which he entered in 1927. The little university's Perkins Observatory with its 69-inch reflector, briefly the second largest telescope in the United States, had just been built and gone into operation. After graduating with a BA magna cum laude in astronomy in 1931, Ernest stayed on one more year and earned his MS with a thesis on the motion of material in the tail of Comet Morehouse, supervised by Nicholas T. Bobrovnikoff. In 1932 Ernest entered the University of California at Berkeley as a graduate student, with a one-year teaching assistantship in the Astronomical Department. This was followed by a two-year Lick Observatory Fellowship. In June 1933 he married Ann McAfee Naylor, who had been a classmate at Delaware High School and Ohio Wesleyan. Ernest did his PhD thesis on spectrophotometry of the Mg I b lines in the solar spectrum, using a high-resolution grating spectrograph on the Berkeley campus, designed by C. Donald Shane, his adviser. In this thesis, Ernest tested and improved the then current theory of strong absorption lines in stellar atmospheres. He also spent several short periods at Lick Observatory on Mount Hamilton

Contributions in the Preparation and Processing of Composite Material Type Silumin 3 - Reinforced Matrix with S235JR Steel Mesh

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Remus Belu-Nica

2015-07-01

Full Text Available In the paper are presented concrete data on developing technological batches of metal composite material (MCM type Silumin 3-reinforced matrix with steel mesh S235JR, with the indicating of the parameter and of the distinct stages of work. The samples from prepared batches were cut along and across by water jet abrasive process and were subjected to a destructive testing program and microstructural examination, obtaining results in concordance with the desired quality. The abrasive material used for cut was GMA granite with the average mesh of 80, the particle size ranging between 150-300 µm, density 2300 kg/m3 and melting point 1240°C.

Microstructural characterization of WC-TiC-Co cutting tools during high-speed machining of P20 mold steel

International Nuclear Information System (INIS)

Farhat, Z.N.

2003-01-01

The wear behavior of tungsten carbide (WC)-TiC-Co cutting tools during cutting P20 tool steel was investigated. Orthogonal cutting tests were performed on a CNC lathe using five speeds, namely, 60, 120, 240, 380 and 600 m/min. Wear, as the width of the wear land, was monitored at five time intervals. Wear characterization of the rake and the flank surfaces as well as the collected chips was performed using scanning electron microscopy (SEM), backscattered electron imaging and energy-dispersive X-ray analysis (EDX). Microhardness of collected chips was also performed to monitor strain hardening effects during cutting. Two dominant wear mechanisms were identified: at high speed (380-600 m/min), wear was found to occur by a melt wear mechanism; at low speed (60-120 m/min), adhesion (built-up edge) followed by delamination was found to be the cause of wear damage. It was also found that deformation in the chips occurred by localized shear deformation

The Effect of ZrO₂ Nanoparticles on the Microstructure and Properties of Sintered WC-Bronze-Based Diamond Composites.

Science.gov (United States)

Sun, Youhong; Wu, Haidong; Li, Meng; Meng, Qingnan; Gao, Ke; Lü, Xiaoshu; Liu, Baochang

2016-05-06

Metal matrix-impregnated diamond composites are widely used in diamond tool manufacturing. In order to satisfy the increasing engineering requirements, researchers have paid more and more attention to enhancing conventional metal matrices by applying novel methods. In this work, ZrO₂ nanoparticles were introduced into the WC-bronze matrix with and without diamond grits via hot pressing to improve the performance of conventional diamond composites. The effects of ZrO₂ nanoparticles on the microstructure, density, hardness, bending strength, and wear resistance of diamond composites were investigated. The results indicated that the hardness and relative density increased, while the bending strength decreased when the content of ZrO₂ nanoparticles increased. The grinding ratio of diamond composites increased significantly by 60% as a result of nano-ZrO₂ addition. The enhancement mechanism was discussed. Diamond composites showed the best overall properties with the addition of 1 wt % ZrO₂ nanoparticles, thus paving the way for further applications.

Study of the sintering behavior of fine, ultrafine and nanocrystalline WC-CO mixtures obtained by high energy milling

International Nuclear Information System (INIS)

Salvador, M. D.; Bonache, V.; Amigo, V.; Busquets, D.

2008-01-01

In this work the sintering behaviour of fine, ultrafine and nanocrystalline WC-12Co mixtures obtained by high energy milling, as well commercial nano powders, have been studied, in order to evaluate the effect of the particle size and the powder processing, in the densification, microstructural development and mechanical properties of the final product. The consolidation of the mixtures has been made by uniaxial pressing and sintering in vacuum, and by hot isostatic pressing. The sintered materials have been evaluated by measures of density, hardness and indentation fracture toughness, and micro structurally characterized by optical microscopy and scanning and transmission electronic microscopy (SEM and TEM). The results show the improvements in resistant behaviour of the materials obtained from nanocrystalline powders, in spite of the grain growth experienced during the sintering. The best results were obtained for the milling nanocrystalline material, which presents values of hardness higher than 180 HV. (Author) 46 refs

Life history of the gall-maker Eugeniamyia dispar Maia, Mendonça-Jr. & Romanowski, 1996 (Diptera, Cecidomyiidae

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M. de S.,Jr. MENDONÇA

Full Text Available The development of the galls of the midge Eugeniamyia dispar Maia, Mendonça-Jr. & Romanowski, 1996 (Diptera: Cecidomyiidae was monitored weekly on its host plant, Eugenia uniflora (Myrtaceae. The work was carried out in the urban area of Porto Alegre, RS, Brazil, from October 1993 to September 1995. Galls were collected from the field and raised in the laboratory to obtain adults. The females oviposit on young leaves of the host plant, with the first instar larvae inducing the gall, which is unilocular. The last instar larvae drop to the soil to pupate and later emerge as adults. The galls occur from late August to early June, when young leaves of the host can be found, with populations peaking during the summer. So far this species is only known from the two southernmost states of Brazil (RS and SC.

Life history of the gall-maker Eugeniamyia dispar Maia, Mendonça-Jr. & Romanowski, 1996 (Diptera, Cecidomyiidae).

Science.gov (United States)

Mendonça, M de S; Romanowski, H P

2002-05-01

The development of the galls of the midge Eugeniamyia dispar Maia, Mendonça-Jr. & Romanowski, 1996 (Diptera: Cecidomyiidae) was monitored weekly on its host plant, Eugenia uniflora (Myrtaceae). The work was carried out in the urban area of Porto Alegre, RS, Brazil, from October 1993 to September 1995. Galls were collected from the field and raised in the laboratory to obtain adults. The females oviposit on young leaves of the host plant, with the first instar larvae inducing the gall, which is unilocular. The last instar larvae drop to the soil to pupate and later emerge as adults. The galls occur from late August to early June, when young leaves of the host can be found, with populations peaking during the summer. So far this species is only known from the two southernmost states of Brazil (RS and SC).

Walter Rowe Courtenay, Jr. (1933–2014)

Science.gov (United States)

Benson, Amy J.

2016-01-01

WALTER R. COURTENAY, JR., ichthyologist and retired professor, Florida Atlantic University, Boca Raton, Florida, died in Gainesville, Florida, on 30 January 2014 at age 80. Walt was born in Neenah, Wisconsin, on 6 November 1933, son of Walter and Emily Courtenay. Walt's interest in fish began at a young age as evidenced by a childhood diary in which at 13 years of age he wrote about his first catch—a two-and-a-half pound “pike” from Lake Winnebago. When Walt turned ten, the family moved from Wisconsin to Nashville, Tennessee, the move precipitated by his father accepting a position as pastor of the First Presbyterian Church. During those early days in Nashville, Walt's father would take summers off and travel to Michigan to teach at Camp Miniwanca along the shore of Lake Michigan where father and son honed their angling skills. It was also at that time Walt's father had definite views on what his son should be doing in adult life—in Walt's case it was to become a medical doctor. However, his Woods Hole internship in marine biology and oceanography toward the end of his undergraduate years was a transformative experience for him so much so that he abandoned all ideas of becoming a medical doctor and instead specialized in ichthyology and oceanography. Apart from the inherent interest and opportunities Woods Hole opened to him, being back at the shore of a large body of water, in this case the Atlantic Ocean, was far more interesting than sitting in lectures on organic chemistry. With that, Walt completed his B.A. degree at Vanderbilt University in 1956. In 1960 while in graduate school in Miami, Walt met and married Francine Saporito, and over the next several years had two children, Walter III and Catherine. He went on to receive his M.S. in 1961 from The Rosenstiel School of Marine and Atmospheric Science at the University of Miami on the systematics of the genus Haemulon (grunts) and his Ph.D. degree in 1965 working under his advisor C. Richard �

Application of in-plane x-ray diffraction technique for residual stress measurement of TiN film/WC-Co alloy

International Nuclear Information System (INIS)

Takago, Shigeki; Yasui, Haruyuki; Awazu, Kaoru; Sasaki, Toshihiko; Hirose, Yukio; Sakurai, Kenji

2006-01-01

An in-plane X-ray diffraction technique was used to measure the residual stress of a CVD (chemical vapor deposition) TiN-coated WC-Co alloy. We could obtain the diffraction pattern from a thin film layer, eliminating that of the substrate. In the case of a conventional X-ray diffractometer, the X-ray penetration depth is about few μm. However, for a grazing incidence beam it is only 0.2μm. Depth profiles of residual stress in TiN film layer were evaluated by the present method and the conventional sin 2 ψ technique. We concluded that the in-plane diffraction technique enables us to determine the residual stress in a DVD-TiN film having an oriented texture. It was found that the residual tensile stress generated a mismatch of the coefficient of thermal expansion between the film and the substrate. (author)

Application of in-plane x-ray diffraction technique for residual stress measurement of TiN film/WC-Co alloy

Energy Technology Data Exchange (ETDEWEB)

Takago, Shigeki; Yasui, Haruyuki; Awazu, Kaoru [Industrial Research Inst. of Ishikawa, Kanazawa, Ishikawa (Japan); Sasaki, Toshihiko; Hirose, Yukio [Kanazawa Univ., Dept. of Materials Science and Engineering, Kanazawa, Ishikawa (Japan); Sakurai, Kenji [National Inst. for Materials Science, Tsukuba, Ibaraki (Japan)

2006-06-15

An in-plane X-ray diffraction technique was used to measure the residual stress of a CVD (chemical vapor deposition) TiN-coated WC-Co alloy. We could obtain the diffraction pattern from a thin film layer, eliminating that of the substrate. In the case of a conventional X-ray diffractometer, the X-ray penetration depth is about few {mu}m. However, for a grazing incidence beam it is only 0.2{mu}m. Depth profiles of residual stress in TiN film layer were evaluated by the present method and the conventional sin{sup 2}{psi} technique. We concluded that the in-plane diffraction technique enables us to determine the residual stress in a DVD-TiN film having an oriented texture. It was found that the residual tensile stress generated a mismatch of the coefficient of thermal expansion between the film and the substrate. (author)

Design and simulation of thermal residual stresses of coatings on WC-Co cemented carbide cutting tool substrate

International Nuclear Information System (INIS)

Li, Anhai; Zhao, Jun; Zang, Jian; Zheng, Wei

2016-01-01

Large thermal residual stresses in coatings during the coating deposition process may easily lead to coating delamination of coated carbide tools in machining. In order to reduce the possibility of coating delamination during the tool failure process, a theoretical method was proposed and a numerical method was constructed for the coating design of WC-Co cemented carbide cutting tools. The thermal residual stresses of multi-layered coatings were analytically modeled based on equivalent parameters of coating properties, and the stress distribution of coatings are simulated by Finite element method (FEM). The theoretically calculated results and the FEM simulated results were verified and in good agreement with the experimental test results. The effects of coating thickness, tool substrate, coating type and interlayer were investigated by the proposed geometric and FEM model. Based on the evaluations of matchability of tool substrate and tool coatings, the basic principles of tool coating design were proposed. This provides theoretical basis for the selection and design of coatings of cutting tools in high-speed machining

J-R Fracture Resistance of SA533 Gr.B-Cl.1 Steel for Reactor Pressure Vessel

Energy Technology Data Exchange (ETDEWEB)

Yoon, Ji-Hyun; Hong, Seokmin; Lee, Bong-Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

A rolled plate might show different mechanical behaviors from a forging, even though they contain same chemical compositions. Furthermore, it is known that the fracture behavior of a rolled plate is very sensitive to material orientation comparing to a forging. In this study, the J-R fracture resistances of SA533 Gr.B-Cl.1 plate were measured at reactor operating temperature and the material orientation sensitivity was discussed. The decrease of fracture resistance of this kind of low alloy steel at an elevated temperature is known as the effect of dynamic strain aging (DSA). It was attributed to that the carbides and grains elongated to primary rolling direction, so that the aspect ratio of carbides and grains in the specimen with T-L orientation is larger. Generally, the hard second phase could take a roll of trigger point of unstable fracture. It is needed that the fracture surfaces of the tested specimens to be examined profoundly.

Desenvolvimento pós-embrionário do intestino anterior de Dermatobia hominis (Linnaeus Jr. (Diptera, Cuterebridae Post-embryonic development of Dermatobia hominis (Linnaeus Jr. (Diptera, Cuterebridae foregut

Directory of Open Access Journals (Sweden)

Ana Maria Vieira

2001-03-01

Full Text Available Foregut in D. hominis (Linnaeus Jr., 1781 as the majority of the larval Diptera somatic tissue, is made up of polytenic cells, and grows at the expenses of the polytenization of its nuclei followed by the increase in size of each cell. The oesophagus, of ectodermic origem, is interiorly covered by a chitinous squamous epithelium that rests upon a very thin basal lamina. This sheet is surrounded by thick muscle bundles. The oesophagus intussuscepts the midgut forming the cardia. The cardia, with three epithelial layers: two internal ones, of ectodermal origin and one external of endodermic origin. At the anterior portion of the cardia, between these two types of epithelium, there is a cluster of small, non polytenic cells, forming the imaginal disk of the foregut. Metamoiphosis begins at the end of the larval period with signs of nuclear degeneration of all the polytenic cells, as well as the increase in number of the imaginal disk ones. The oesophagic portion intussuscepted into the cardia, everts; its cells suffer apoptosis and are replaced by the new cells growing from the imaginal disk. The external layer cells also degenerate and are pinched off into the lumen of the very anterior portion of the midgut. The newly formed oesophagus intussuscepts "de novo" to form the two internal layers of the adult cardia. At the same time the midgut regenerative cells grow anteriorly to form the new external layer of the adult cardia.

Hip-Hop to Health Jr. Obesity Prevention Effectiveness Trial: Post-Intervention Results

Science.gov (United States)

Fitzgibbon, M. L.; Stolley, M. R.; Schiffer, L.; Braunschweig, C. L.; Gomez, S. L.; Van Horn, L.; Dyer, A.

2013-01-01

The preschool years offer an opportunity to interrupt the trajectory toward obesity in black children. The Hip-Hop to Health Jr. Obesity Prevention Effectiveness Trial was a group-randomized controlled trial assessing the feasibility and effectiveness of a teacher-delivered weight control intervention for black preschool children. The 618 participating children were enrolled in 18 schools administered by the Chicago Public Schools. Children enrolled in the 9 schools randomized to the intervention group received a 14-week weight control intervention delivered by their classroom teachers. Children in the 9 control schools received a general health intervention. Height and weight, physical activity, screen time, and diet data were collected at baseline and post-intervention. At post-intervention, children in the intervention schools engaged in more moderate-to vigorous physical activity than children in the control schools (difference between adjusted group means=7.46 min/day, p=.02). Also, children in the intervention group had less total screen time (−27.8 min/day, p=.05). There were no significant differences in BMI, BMI Z score, or dietary intake. It is feasible to adapt an obesity prevention program to be taught by classroom teachers. The intervention showed positive influences on physical activity and screen time, but not diet. Measuring diet and physical activity in preschool children remains a challenge, and interventions delivered by classroom teachers require both intensive initial training and ongoing individualized supervision. PMID:21193852

Características de los recubrimientos WC-NiCrBSiFe en función del sistema de proyección térmica

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Higuera-Hidalgo, V.

2004-10-01

Full Text Available WC-NiCrBSiFe coatings are normally used as protection against heat, corrosion and erosion actions encountered in superheater and reheater tubes in power plant boilers. This coating was thermal-spray projected using different procedures (plasma, HVOF and HFPD onto stainless steel specimens. The microstructures, porosities, oxide contents and microhardnesses of the coatings were determined. Thermal fatigue tests under simulative power plant service conditions were conducted in an experimental combustion chamber and, finally, the adhesion between the substrate and the coating layer was evaluated by means of tensile tests.The obtained results are discussed, and special attention was paid to the specific characteristics of the different spraying procedures.

El material tipo cermet WC-NiCrBSiFe se emplea como elemento protector frente al desgaste, en elementos de calderas de vapor, como son los sobrecalentadores y recalentadores de vapor, donde las condiciones de servicio tan severas (alta temperatura, erosión por cenizas volantes, etc. acortan notablemente la vida útil de los materiales convencionales empleados. En este trabajo se ha realizado la proyección térmica de este recubrimiento por arco plasma no transferido, proyección mediante llama a elevada velocidad (HVOF y proyección por detonación a elevada frecuencia (HFPD. Se determinaron las microestructuras, porosidades, contenidos en óxidos y microdurezas de los distintos recubrimientos obtenidos. También, se llevaron a cabo ensayos de fatiga térmica en condiciones similares a las imperantes en el interior de una caldera, mediante el empleo de un combustor experimental. Finalmente, se determinó la adherencia de las capas a los sustratos receptores, mediante ensayos de tracción. Los resultados obtenidos son discutidos en función de las características específicas de los diferentes sistemas de proyección utilizados.

Alberto Urrets-Zavalía Jr (1920-2010): An Argentinian contributor to ophthalmology.

Science.gov (United States)

Grzybowski, Andrzej; Urrets-Zavalía, Julio A; Ascaso, Francisco J

2016-05-01

Alberto Urrets-Zavalía Jr was born in Córdoba (Argentina) in 1920. Chairman of the Department of Ophthalmology of the National University of Córdoba and founder of the Cornea and Glaucoma Surgical Center in the same city, in 1956 he created the first residency programme in Ophthalmology in his country. He founded the first Eye Bank and introduced one of the first argon laser photocoagulators in South America. He authored around 200 scientific presentations and publications, describing new findings and clinical entities. Thus, his individualisation of the cyclovertical component in strabismus contributed to important evolution of ideas concerning pathogenesis and therapy in oculomotor disorders of infancy. He was the first to propose the dehydration of the vitreous body in glaucoma patients before ocular surgery and developed a fixation pick and scleral depressor for retinal detachment surgery. He also described a new technique, the V-Z procedures for the correction of senile ectropion. In 1968, he published his Décollement de la rétine, considered a masterpiece in retinal detachment literature for many years. Urrets-Zavalía died in his native city at the age of 89. His prolific scientific and educational contributions make him one of the most brilliant and influential ophthalmologists of the 20th-century. © The Author(s) 2014.

Effects of high temperature treatment on microstructure and mechanical properties of laser-clad NiCrBSi/WC coatings on titanium alloy substrate

International Nuclear Information System (INIS)

Li, Guang Jie; Li, Jun; Luo, Xing

2014-01-01

Laser-clad composite coatings on the Ti6Al4V substrate were heat-treated at 700, 800, and 900 °C for 1 h. The effects of post-heat treatment on the microstructure, microhardness, and fracture toughness of the coatings were investigated by scanning electron microscopy, X-ray diffractometry, energy dispersive spectroscopy, and optical microscopy. The wear resistance of the coatings was evaluated under dry reciprocating sliding friction at room temperature. The coatings mainly comprised some coarse gray blocky (W,Ti)C particles accompanied by the fine white WC particles, a large number of black TiC cellular/dendrites, and the matrix composed of NiTi and Ni 3 Ti; some unknown rich Ni- and Ti-rich particles with sizes ranging from 10 nm to 50 nm were precipitated and uniformly distributed in the Ni 3 Ti phase to form a thin granular layer after heat treatment at 700 °C. The granular layer spread from the edge toward the center of the Ni 3 Ti phase with increasing temperature. A large number of fine equiaxed Cr 23 C 6 particles with 0.2–0.5 μm sizes were observed around the edges of the NiTi supersaturated solid solution when the temperature was further increased to 900 °C. The microhardness and fracture toughness of the coatings were improved with increased temperature due to the dispersion-strengthening effect of the precipitates. Dominant wear mechanisms for all the coatings included abrasive and delamination wear. The post-heat treatment not only reduced wear volume and friction coefficient, but also decreased cracking susceptibility during sliding friction. Comparatively speaking, the heat-treated coating at 900 °C presented the most excellent wear resistance. - Highlights: • TiC + WC reinforced intermetallic compound matrix composite coatings were produced. • The formation mechanism of the reinforcements was analyzed. • Two precipitates were generated at elevated temperature. • Cracking susceptibility and microhardness of the coatings were improved

Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y2O3 particles

International Nuclear Information System (INIS)

Genc, Aziz; Luetfi Ovecoglu, M.

2010-01-01

Research highlights: → Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. → Reinforcement of the selected Ni-W powders with WC and Y 2 O 3 particles and further MA together for 12 h. → There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. → Sintering of the developed composites and the characterization investigations of the sintered samples. → Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y 2 O 3 particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 o C for 1 h under Ar and H 2 gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

O desenvolvimento de competências por meio da extensão universitária: o caso da Global Jr. ESPM-SP na formação do diplomata corporativo

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Diego Bonaldo Coelho

2017-09-01

Full Text Available O artigo apresenta o debate sobre a relevância da extensão universitária como ação para o desenvolvimento de competências acadêmicas e profissionais em graduandos de Relações Internacionais. Para investigação, utilizou-se como fio condutor de análise um modelo específico de atividade extensionista, a empresa júnior, por meio de estudo de caso da Global Jr. da ESPM-SP. Os resultados observados sugerem impactos positivos do empreendimento tanto na formação quanto na empregabilidade dos estudantes, corroborando estudos realizados por Terrim et al (2015 e Barbosa et al (2016. The paper presents the debate over the relevancy of university extension as a source of academic and professional skills development in undergraduate students of International Relations. For the investigation it was used a specific model of extensionist activity, the junior company, through the case study of Global Jr. from ESPM-SP. The results which were observed suggest positive impacts of the enterprise both in education and in employment of the students, corroborating with studies conducted by Terrim et al (2015 and Barbosa et al (2016.

Characterization of the Photon Counting CHASE Jr., Chip Built in a 40-nm CMOS Process With a Charge Sharing Correction Algorithm Using a Collimated X-Ray Beam

Energy Technology Data Exchange (ETDEWEB)

Krzyżanowska, A. [AGH-UST, Cracow; Deptuch, G. W. [Fermilab; Maj, P. [AGH-UST, Cracow; Gryboś, P. [AGH-UST, Cracow; Szczygieł, R. [AGH-UST, Cracow

2017-08-01

This paper presents the detailed characterization of a single photon counting chip, named CHASE Jr., built in a CMOS 40-nm process, operating with synchrotron radiation. The chip utilizes an on-chip implementation of the C8P1 algorithm. The algorithm eliminates the charge sharing related uncertainties, namely, the dependence of the number of registered photons on the discriminator’s threshold, set for monochromatic irradiation, and errors in the assignment of an event to a certain pixel. The article presents a short description of the algorithm as well as the architecture of the CHASE Jr., chip. The analog and digital functionalities, allowing for proper operation of the C8P1 algorithm are described, namely, an offset correction for two discriminators independently, two-stage gain correction, and different operation modes of the digital blocks. The results of tests of the C8P1 operation are presented for the chip bump bonded to a silicon sensor and exposed to the 3.5- μm -wide pencil beam of 8-keV photons of synchrotron radiation. It was studied how sensitive the algorithm performance is to the chip settings, as well as the uniformity of parameters of the analog front-end blocks. Presented results prove that the C8P1 algorithm enables counting all photons hitting the detector in between readout channels and retrieving the actual photon energy.

Video Release: 47th Vice President of the United States Joseph R. Biden Jr. Speech at HUPO2017 Global Leadership Gala | Office of Cancer Clinical Proteomics Research

Science.gov (United States)

The Human Proteome Organization (HUPO) has released a video of the keynote speech given by the 47th Vice President of the United States of America Joseph R. Biden Jr. at the HUPO2017 Global Leadership Gala. Under the gala theme “International Cooperation in the Fight Against Cancer,” Biden recognized cancer as a collection of related diseases, the importance of data sharing and harmonization, and the need for collaboration across scientific disciplines as inflection points in cancer research.

Facial electromyogram and heart-rate correlates of a paradoxical attitude change to antinuclear war information

International Nuclear Information System (INIS)

Vigne, J.J.; Dale, J.A.; Klions, H.L.

1988-01-01

The effects of film images versus film descriptions of the effects of nuclear explosions (versus a no-film control) on corrugator muscle tension, heart rate, attitude and mood were investigated. The last 5 min. of the images were associated with more corrugator tension for that condition when compared to the last 5 min. of the description condition. The groups did not differ in heart rate but women in both groups showed an increase in heart rate whereas men in both groups showed a decrease in heart rate. Film groups did not differ in their significant increases in anxiety, hostility, and depression on the Multiple Adjective Affect Checklist. On the pretest there was no significant correlation between scores on Betts' Questionnaire Upon Mental Imagery and scores on Goldenring and Doctor's index of concern for nuclear war. The vivid-image film group showed a decrease in concern for nuclear war when compared to the descriptive film group and the no-film control

Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y{sub 2}O{sub 3} particles

Energy Technology Data Exchange (ETDEWEB)

Genc, Aziz, E-mail: agenc@itu.edu.t [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey); Luetfi Ovecoglu, M. [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey)

2010-10-15

Research highlights: {yields} Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. {yields} Reinforcement of the selected Ni-W powders with WC and Y{sub 2}O{sub 3} particles and further MA together for 12 h. {yields} There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. {yields} Sintering of the developed composites and the characterization investigations of the sintered samples. {yields} Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y{sub 2}O{sub 3} particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 {sup o}C for 1 h under Ar and H{sub 2} gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

Structure and dynamics of the gp120 V3 loop that confers noncompetitive resistance in R5 HIV-1(JR-FL to maraviroc.

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Yuzhe Yuan

Full Text Available Maraviroc, an (HIV-1 entry inhibitor, binds to CCR5 and efficiently prevents R5 human immunodeficiency virus type 1 (HIV-1 from using CCR5 as a coreceptor for entry into CD4(+ cells. However, HIV-1 can elude maraviroc by using the drug-bound form of CCR5 as a coreceptor. This property is known as noncompetitive resistance. HIV-1(V3-M5 derived from HIV-1(JR-FLan is a noncompetitive-resistant virus that contains five mutations (I304V/F312W/T314A/E317D/I318V in the gp120 V3 loop alone. To obtain genetic and structural insights into maraviroc resistance in HIV-1, we performed here mutagenesis and computer-assisted structural study. A series of site-directed mutagenesis experiments demonstrated that combinations of V3 mutations are required for HIV-1(JR-FLan to replicate in the presence of 1 µM maraviroc, and that a T199K mutation in the C2 region increases viral fitness in combination with V3 mutations. Molecular dynamic (MD simulations of the gp120 outer domain V3 loop with or without the five mutations showed that the V3 mutations induced (i changes in V3 configuration on the gp120 outer domain, (ii reduction of an anti-parallel β-sheet in the V3 stem region, (iii reduction in fluctuations of the V3 tip and stem regions, and (iv a shift of the fluctuation site at the V3 base region. These results suggest that the HIV-1 gp120 V3 mutations that confer maraviroc resistance alter structure and dynamics of the V3 loop on the gp120 outer domain, and enable interactions between gp120 and the drug-bound form of CCR5.

Multi-response optimization of machining characteristics in ultrasonic machining of WC-Co composite through Taguchi method and grey-fuzzy logic

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Ravi Pratap Singh

2018-01-01

Full Text Available This article addresses the application of grey based fuzzy logic coupled with Taguchi’s approach for optimization of multi performance characteristics in ultrasonic machining of WC-Co composite material. The Taguchi’s L-36 array has been employed to conduct the experimentation and also to observe the influence of different process variables (power rating, cobalt content, tool geometry, thickness of work piece, tool material, abrasive grit size on machining characteristics. Grey relational fuzzy grade has been computed by converting the multiple responses, i.e., material removal rate and tool wear rate obtained from Taguchi’s approach into a single performance characteristic using grey based fuzzy logic. In addition, analysis of variance (ANOVA has also been attempted in a view to identify the significant parameters. Results revealed grit size and power rating as leading parameters for optimization of multi performance characteristics. From the microstructure analysis, the mode of material deformation has been observed and the critical parameters (i.e., work material properties, grit size, and power rating for the deformation mode have been established.

Molecular and biological characterization of the 5 human-bovine rotavirus (WC3)-based reassortant strains of the pentavalent rotavirus vaccine, RotaTeq (registered)

International Nuclear Information System (INIS)

Matthijnssens, Jelle; Joelsson, Daniel B.; Warakomski, Donald J.; Zhou, Tingyi; Mathis, Pamela K.; Maanen, Marc-Henri van; Ranheim, Todd S.; Ciarlet, Max

2010-01-01

RotaTeq (registered) is a pentavalent rotavirus vaccine that contains five human-bovine reassortant strains (designated G1, G2, G3, G4, and P1) on the backbone of the naturally attenuated tissue culture-adapted parental bovine rotavirus (BRV) strain WC3. The viral genomes of each of the reassortant strains were completely sequenced and compared pairwise and phylogenetically among each other and to human rotavirus (HRV) and BRV reference strains. Reassortants G1, G2, G3, and G4 contained the VP7 gene from their corresponding HRV parent strains, while reassortants G1 and G2 also contained the VP3 gene (genotype M1) from the HRV parent strain. The P1 reassortant contained the VP4 gene from the HRV parent strain and all the other gene segments from the BRV WC3 strain. The human VP7s had a high level of overall amino acid identity (G1: 95-99%, G2: 94-99% G3: 96-100%, G4: 93-99%) when compared to those of representative rotavirus strains of their corresponding G serotypes. The VP4 of the P1 reassortant had a high identity (92-97%) with those of serotype P1A[8] HRV reference strains, while the BRV VP7 showed identities ranging from 91% to 94% to those of serotype G6 HRV strains. Sequence analyses of the BRV or HRV genes confirmed that the fundamental structure of the proteins in the vaccine was similar to those of the HRV and BRV references strains. Sequences analyses showed that RotaTeq (registered) exhibited a high degree of genetic stability as no mutations were identified in the material of each reassortant, which undergoes two rounds of replication cycles in cell culture during the manufacturing process, when compared to the final material used to fill the dosing tubes. The infectivity of each of the reassortant strains of RotaTeq (registered) , like HRV strains, did not require the presence of sialic acid residues on the cell surface. The molecular and biologic characterization of RotaTeq (registered) adds to the significant body of clinical data supporting the

Interacción térmica recubrimiento-sustrato en la proyección a alta velocidad (HVOF de partículas (polvo de WC-Co

Directory of Open Access Journals (Sweden)

Sobolev, V. V.

1995-06-01

Full Text Available The mathematical simulation of the thermal interaction between a 34CrMo4 (UNS-G41350 steel substrate and a coating formed by the droplets of WC-12 % Co powder particles during HVOF spraying is undertaken. Analysis of the heat transfer processes permitted the investigation of the temperature evolution, coating solidification, substrate fusion and solidification, particular features of the thermal interactions between the substrate and the coating as well as between the successive coating layers. The analysis has also permitted to estimate the optimal conditions of the substrate and the coating structure formation. The obtained results were used in subsequent articles to predict the structure parameters, which agree with the experimental data.

Se utiliza la simulación matemática para establecer la interacción térmica entre un substrato y un recubrimiento obtenido mediante proyección térmica de alta velocidad, HVOF. El substrato es un acero 34CrMo4(UNS-G41350 y el recubrimiento está formado por la solidificación de gotas semifundidas de partículas de polvo de WC-12 % Co. El análisis del proceso de transferencia de calor permite la investigación de la evolución de la temperatura, la solidificación del recubrimiento, la fusión y posterior solidificación del substrato, las características peculiares de la interacción térmica entre el substrato y la primera capa de recubrimiento, así como con las diferentes capas sucesivas, y la estimación de las condiciones óptimas para la formación de la estructura del substrato y del recubrimiento. Los resultados obtenidos se han utilizado en posteriores artículos para predecir parámetros estructurales que están, por su parte, en concordancia con los datos experimentales.

Desempeño de insertos de WC recubiertos con nanomulticapas de [TiN/TiAlN]n en el mecanizado del acero endurecido AISI 4340

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Luis Henry Moreno

2011-01-01

Full Text Available En el presente trabajo se muestran los resultados de la resistencia al desgaste de insertos de carburo de tungsteno (WC sin recubrir y recubiertos con multinanocapas de [TiN/TiAlN]n con un espesor total promedio del recubrimiento de 4 ¿m, así como de insertos recubiertos con monocapas comerciales de TiCN-Al2O3-TiN (TINAL. Se realizaron ensayos de vida útil, análisis de temperatura en la zona de corte, mediciones de rugosidad superfi cial sobre la pieza y sobre los insertos en la superfi cie de ataque, análisis de huella de contacto entre viruta-insertos y análisis de composición química (EDS. Los ensayos se realizaron sobre piezas de acero AISI 4340 utilizando régimen de corte de acabado y aplicando altas velocidades de corte (HSC. Los resultados de mecanizado de acero, para un recorrido de 8.000 metros con diferentes insertos de carburo de tungsteno (WC, sin recubrimiento y recubiertos presentaron valores de desgaste de 0,117 mm y 0,138 mm; en relación a los insertos recubiertos con 300 y 200 bicapas de TiN/TiAlN, respectivamente. De igual manera, los insertos recubiertos con TINAL exhibieron valores de desgaste de 0,174 mm. Además, los valores de temperatura en la zona de corte y para una velocidad de corte de 176,6 m/mim fueron de 522,6 oC para los recubrimientos con 300 bicapas, de 721,4 oC para aquellos con 200 bicapas, y de 1.327,6 oC para los insertos recubiertos con TINAL. La disminución de la temperatura en la zona de corte, relacionada con un menor coefi ciente de fricción y una menor fuerza de corte, contribuyeron al alargamiento de la vida útil de los insertos.

Dr Albert L. Rhoton Jr's Time at the Mayo Clinic: The Beginnings of a Remarkable Career.

Science.gov (United States)

Rayan, Tarek; Carlson, Matthew L; Piepgras, David G; Link, Michael J; Van Gompel, Jamie J

2017-08-09

Dr Albert L. Rhoton Jr became the focal point of neurosurgery's evolution in understanding the intricate and complex microanatomy of the human brain over the last 4 decades. His pioneering work on cadaveric specimens proved to be a pivotal endeavor in the pursuit to better understand the complex microsurgical anatomy of cranial surgery. This paper details his early career at the Mayo Clinic in Rochester, Minnesota. A comprehensive review and synthesis of data acquired from the institutional historical archives including the Annual Reports to the Executive Committee, the Reports to the Board of Directors, the MAYOVOX Newsletter, the illustration archives of the Mayo Clinic Division of Creative Media, staff biographies, curriculum vitae, personal interviews, as well as full-text journal articles, and book publications was performed. Dr Rhoton was engaged in a busy clinical practice as a young staff at the Mayo Clinic. Records show he focused on tackling complex intracranial pathologies along with numerous basic research and neuroanatomy projects that became a major part of his life's work and passion. He was a great teacher and friend to countless individuals and his work will continue to impact and improve the care provided to neurosurgery patients for generations to come. Copyright © 2017 by the Congress of Neurological Surgeons.

PROFESSOR ZDZISŁAW ŻYGULSKI JR.: AN OUTSTANDING PERSON, A GREAT PERSONALITY, A MUSEUM PROFESSIONAL, A RESEARCHER ON ANTIQUE WEAPONS, ORIENTAL ART AND EUROPEAN PAINTING (1921–2015)

OpenAIRE

Teresa Grzybkowska

2017-01-01

Professor Zdzisław Żygulski Jr. (1921–2015) was one of the most prominent Polish art historians of the second half of the 20th century. He treated the history of art as a broadly understood science of mankind and his artistic achievements. His name was recognised in global research on antique weapons, and among experts on Rembrandt and Leonardo da Vinci. He studied museums and Oriental art. He wrote 35 books, about 200 articles, and numerous essays on art; he wrote for the daily press about h...

Eagle Pass Jr. High Seismology Team: Strategies for Engaging Middle School "At-Risk" Students in Authentic Research

Science.gov (United States)

Brunt, M. R.; Ellins, K. K.; Frohlich, C. A.

2011-12-01

In 2008, during my participation in the NSF-sponsored Texas Earth & Space Science (TXESS) Revolution professional development program, I was awarded an AS-1 seismograph through IRIS's Seismographs in Schools Program. This program serves to create an international educational seismic network that allows teachers across the country and around the world to share seismic data in real-time using online tools, classroom activities, and technical support documents for seismic instruments. Soon after receiving my AS-1, I founded and began sponsoring the Eagle Pass Jr. High Seismology Team which consists of selected 7th and 8th grade students. Eagle Pass Jr. High is a Title 1 school that serves a predominantly "at-risk" Hispanic population. We meet after school once a week to learn about earthquakes, seismic waves, analyze recorded seismic event data using computer software programming, and correspond with other students from schools around the country. This team approach has been well received by fellow TXESS Revolution teachers with AS-1 seismographs and will be implemented by David Boyd, STEM coordinator for Williams Preparatory Academy in Dallas, Texas this fall 2011. All earthquakes recorded by our seismograph station (EPTX), which has remained online and actively recording seismic data since 2008, are catalogued and then plotted on a large world map displayed on my classroom wall. A real-time seismogram image updates every five minutes and along with all earthquakes recorded since installation can be viewed on our webpage http://www.iris.edu/hq/ssn/schools/view/eptx. During the 2010-2011 school year, my seismology team and I participated in an earthquake research study led by Dr. Cliff Frohlich at the Institute for Geophysics. The study examined seismograms and felt reports for the 25 April 2010 Alice, Texas, earthquake, in order to investigate its possible connection to oil and gas production in the Stratton oil and gas field. A research paper detailing our findings

Estudio del comportamiento durante la sinterización de mezclas WC-Co finas, ultrafinas y nanocristalinas obtenidas por molienda de alta energía

Directory of Open Access Journals (Sweden)

Salvador, M. D.

2008-10-01

Full Text Available In this work the sintering behaviour of fine, ultrafine and nanocrystalline WC-12Co mixtures obtained by high energy milling, as well as commercial nanopowders, have been studied, in order to evaluate the effect of the particle size and the powder processing, in the densification, microstructural development and mechanical properties of the final product. The consolidation of the mixtures has been made by uniaxial pressing and sintering in vacuum, and by hot isostatic pressing. The sintered materials have been evaluated by measures of density, hardness and indentation fracture toughness, and microstructurally characterized by optical microscopy and scanning and transmission electronic microscopy (SEM and TEM. The results show the improvements in resistant behaviour of the materials obtained from nanocrystalline powders, in spite of the grain growth experienced during the sintering. The best results were obtained for the milling nanocrystalline material, which presents values of hardness higher than 1800 HV.

En este trabajo se ha estudiado el comportamiento, durante la sinterización, de mezclas WC-12Co finas, ultrafinas y nanométricas obtenidas por molienda de alta energía y de material nanométrico comercial, a fin de evaluar el efecto del tamaño de partícula y del proceso de obtención del polvo en la densificación, desarrollo microestructural y propiedades mecánicas del producto final. La consolidación de las mezclas se ha realizado mediante compactación uniaxial y sinterización en vacío y por compactación isostática en caliente. Los materiales sinterizados se han evaluado mediante medidas de densidad, dureza y tenacidad a fractura por indentación y se han caracterizado microestructuralmente mediante microscopía óptica y microscopía electrónica de barrido y de transmisión. Los resultados obtenidos ponen de manifiesto las mejoras en comportamiento resistente de los materiales obtenidos a partir polvos nanométricos, a

Effect of rare earth oxide addition on microstructures of ultra-fine WC-Co particulate reinforced Cu matrix composites prepared by direct laser sintering

International Nuclear Information System (INIS)

Gu Dongdong; Shen Yifu; Zhao Long; Xiao Jun; Wu Peng; Zhu Yongbing

2007-01-01

This paper presents a detailed investigation into the influence of the rare earth (RE) oxide (La 2 O 3 ) addition upon the densification and the resultant microstructural characteristics of the submicron WC-Co particulate reinforced Cu matrix composites prepared by direct laser sintering. It is found that the relative density of the laser sintered sample with 1 wt.% La 2 O 3 addition increased by 11.5% as compared with the sample without RE addition. The addition of RE element favored the microstructural refinement and improved the particulate dispersion homogeneity and the particulate/matrix interfacial coherence. The metallurgical functions of the RE element in improving the sinterability were also addressed. It shows that due to the unique properties of RE element such as high surface activity and large atomic radius, the addition of trace RE element can decrease the surface tension of the melt, resist the grain growth coarsening and increase the heterogeneous nucleation rate during laser sintering

The Manuel Lujan Jr. Neutron Scattering Center (LANSCE) experiment reports 1993 run cycle. Progress report

Energy Technology Data Exchange (ETDEWEB)

Farrer, R.; Longshore, A. [comps.

1995-06-01

This year the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) ran an informal user program because the US Department of Energy planned to close LANSCE in FY1994. As a result, an advisory committee recommended that LANSCE scientists and their collaborators complete work in progress. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and a associated Proton Storage Ring (PSR), which can Iter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory (LANL) may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. This year, a total of 127 proposals were submitted. The proposed experiments involved 229 scientists, 57 of whom visited LANSCE to participate in measurements. In addition, 3 (nuclear physics) participating research teams, comprising 44 scientists, carried out experiments at LANSCE. Instrument beam time was again oversubscribed, with 552 total days requested an 473 available for allocation.

The Manuel Lujan Jr. Neutron Scattering Center (LANSCE) experiment reports 1993 run cycle. Progress report

International Nuclear Information System (INIS)

Farrer, R.; Longshore, A.

1995-06-01

This year the Manuel Lujan Jr. Neutron Scattering Center (LANSCE) ran an informal user program because the US Department of Energy planned to close LANSCE in FY1994. As a result, an advisory committee recommended that LANSCE scientists and their collaborators complete work in progress. At LANSCE, neutrons are produced by spallation when a pulsed, 800-MeV proton beam impinges on a tungsten target. The proton pulses are provided by the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator and a associated Proton Storage Ring (PSR), which can Iter the intensity, time structure, and repetition rate of the pulses. The LAMPF protons of Line D are shared between the LANSCE target and the Weapons Neutron Research (WNR) facility, which results in LANSCE spectrometers being available to external users for unclassified research about 80% of each annual LAMPF run cycle. Measurements of interest to the Los Alamos National Laboratory (LANL) may also be performed and may occupy up to an additional 20% of the available beam time. These experiments are reviewed by an internal program advisory committee. This year, a total of 127 proposals were submitted. The proposed experiments involved 229 scientists, 57 of whom visited LANSCE to participate in measurements. In addition, 3 (nuclear physics) participating research teams, comprising 44 scientists, carried out experiments at LANSCE. Instrument beam time was again oversubscribed, with 552 total days requested an 473 available for allocation

Effect of cobalt content on wear and corrosion behaviors of electrodeposited Ni-Co/WC nano-composite coatings.

Science.gov (United States)

Amadeh, A; Ebadpour, R

2013-02-01

Metal-ceramic composite coatings are widely used in automotive and aerospace industries as well as micro-electronic systems. Electrodeposition is an economic method for application of these coatings. In this research, nickel-cobalt coatings reinforced by nano WC particles were applied on carbon steel substrate by pulse electrodeposition from modified Watts bath containing different amounts of cobalt sulphate as an additive. Saccharin and sodium dodecyl sulphate (SDS) were also added to electroplating bath as grain refiner and surfactant, respectively. The effect of cobalt content on wear and corrosion behavior of the coatings was investigated. Wear and corrosion properties were assessed by pin-on-disk and potentiodynamic polarization methods, respectively. Phase analysis was performed by X-ray diffraction (XRD) using CuK(alpha) radiation and the worn surfaces were studied by means of Scanning Electron Microscopy (SEM). The results showed that the addition of cobalt improved the wear resistance of the coatings. In the presence of 18 g/L cobalt in electrodeposition bath, the wear rate of the coating decreased to 0.002 mg/m and the coefficient of friction reduced to 0.695 while they were 0.004 mg/m and 0.77 in the absence of cobalt, respectively. This improvement in wear properties can be attributed to the formation of hcp phase in metallic matrix. Meanwhile, the corrosion resistance of the coatings slightly reduced because cobalt is more active metal with respect to nickel.

Hip-Hop to Health Jr., an obesity prevention program for minority preschool children: baseline characteristics of participants.

Science.gov (United States)

Stolley, Melinda R; Fitzgibbon, Marian L; Dyer, Alan; Van Horn, Linda; KauferChristoffel, Katherine; Schiffer, Linda

2003-03-01

The prevalence of obesity in the United States is a significant public health problem. Many obesity-related risk factors are more prevalent in minority populations. Given the recalcitrant nature of weight loss interventions for adults, prevention of overweight and obesity has become a high priority. The present study reports baseline data from an obesity prevention intervention developed for minority preschool children. Hip-Hop to Health Jr. is a 5-year randomized controlled intervention that targets 3- to 5-year-old minority children enrolled in 24 Head Start programs. Our primary aim is to test the effect of the intervention on change in body mass index. Data were collected on sociodemographic, anthropometric, behavioral, and cognitive variables for the children and parents at baseline. Participants included 416 black children, 337 black parents, 362 Latino children, and 309 Latino parents. Using body mass index for age and sex > or = the 95th percentile as the definition of overweight, 15% of the black children and 28% of the Latino children were overweight. More than 75% of the parents were either overweight or obese. The development of interventions to effectively prevent or control obesity early in life is crucial. These data highlight the escalating problem of weight control in minority populations.

MAIL3.1 : a computer program generating cross section sets for SIMCRI, ANISN-JR, KENO IV, KENO V, MULTI-KENO, MULTI-KENO-2 and MULTI-KENO-3.0

International Nuclear Information System (INIS)

Suyama, Kenya; Komuro, Yuichi; Takada, Tomoyuki; Kawasaki, Hiromitsu; Ouchi, Keisuke

1998-02-01

This report is a user's manual of the computer program MAIL3.1 which generates various types of cross section sets for neutron transport programs such as SIMCRI, ANISN-JR, KENO IV, KENO V, MULTI-KENO, MULTI-KENO-2 and MULTI-KENO-3.0. MAIL3.1 is a revised version of MAIL3.0 that was opened in 1990. It has all of abilities of MAIL3.0 and has two more functions as shown in following. 1. AMPX-type cross section set generating function for KENO V. 2. Enhanced function for user of 16 group Hansen-Roach library. (author)

MAIL3.1 : a computer program generating cross section sets for SIMCRI, ANISN-JR, KENO IV, KENO V, MULTI-KENO, MULTI-KENO-2 and MULTI-KENO-3.0

Energy Technology Data Exchange (ETDEWEB)

Suyama, Kenya; Komuro, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Takada, Tomoyuki; Kawasaki, Hiromitsu; Ouchi, Keisuke

1998-02-01

This report is a user`s manual of the computer program MAIL3.1 which generates various types of cross section sets for neutron transport programs such as SIMCRI, ANISN-JR, KENO IV, KENO V, MULTI-KENO, MULTI-KENO-2 and MULTI-KENO-3.0. MAIL3.1 is a revised version of MAIL3.0 that was opened in 1990. It has all of abilities of MAIL3.0 and has two more functions as shown in following. 1. AMPX-type cross section set generating function for KENO V. 2. Enhanced function for user of 16 group Hansen-Roach library. (author)

Influence of reinforcement weight fraction on microstructure and properties of submicron WC-Cop/Cu bulk MMCs prepared by direct laser sintering

International Nuclear Information System (INIS)

Gu, Dongdong; Shen, Yifu

2007-01-01

Direct metal laser sintering (DMLS), due to its flexibility in materials and shapes, exhibits a great potential for fabricating complex shaped bulk metal matrix composites (MMCs). In the present work, the submicron WC-10% Co particulate reinforced Cu matrix composites were prepared using DMLS. The influence of reinforcement content on the sintered densification and the attendant microstructures, e.g. the dispersion homogeneity of the reinforcing particulates and the interfacial bonding ability, was investigated using scanning electron microscopy (SEM), energy disperse X-ray (EDX) spectroscopy, and atomic force microscope (AFM). It shows that using a low reinforcement content of 20 wt.% results in a poor densification with severe balling phenomena, due to a higher average composite coefficient of thermal expansion (CTE) and a superheating of the melt. A heterogeneous microstructure with a significant particulate aggregation is obtained at a high reinforcement content of 40 wt.%, because of a limited liquid formation and the resultant high liquid viscosity and reduced Marangoni effect. Using an optimal reinforcement content of 30 wt.% leads to a uniform distribution of the reinforcing particulates and a compatible interfacial microstructure, so as to obtain a favorable sintered density of 90.3% theoretical density

The use of contrast variation in small angle neutron scattering on the low-Q diffractometer at the Manuel Lujuan Jr. Neutron Scattering Center at Los Alamos National Laboratory (LANSCE)

International Nuclear Information System (INIS)

Spaccavento, J.

1993-01-01

As a Department of Energy Teacher Research Associate at Los Alamos National Laboratory this past summer, the author was given the opportunity to exit the class-room and enter the world of intense scientific research for an eight week period. In this paper the author briefly describes the Manual Lujan Jr. Neutron Scattering Center at Los Alamos, then focuses specifically on the Low-Q Diffractometer which was the instrument he worked on. The author details one specific experimental technique namely open-quotes Contrast Variation,close quotes and closes by briefly presenting several other interesting applications of neutron scattering

FIBROUS MONOLITH WEAR RESISTANT COMPONENTS FOR THE MINING INDUSTRY; SEMIANNUAL

International Nuclear Information System (INIS)

Mark J. Rigali; Kenneth L. Knittel; Mike L. Fulcher

2002-01-01

During this reporting period, work continued on development of formulations using the materials identified as contenders for the fibrous monolith wear resistant components. The FM structures fabricated were: diamond/WC-Co, B(sub 4)C/WC-Co, TiB(sub 2)/WC-Co, WC-Co/Co, WC-Co/WC-Co. Results of our consolidation densification studies on these systems lead to the down-selection of WC-Co/WC-Co, WC-Co/Co and diamond/WC-Co for further development for mining applications including drill bit inserts, roof bit inserts, radial tools conical tools and wear plates (WC-Co based system only) for earth moving equipment. Prototype component fabrication focused on the fabrication of WC-Co/WC-Co FM conical tools, diamond/WC-Co coated drill bit insert prototypes. Fabrication of WC-Co/WC-Co FM insert prototypes for a grader blade is also underway. ACR plans to initiate field-testing of the drill bit insert prototypes and the grader blade insert this summer (2002). The first WC-Co/WC-Co FM conical tool prototypes were sent to Kennametal for evaluation towards the end of the current reporting period

MITOLOGIAS MIDIÁTICAS DE PELÉ, RONALDINHO GAÚCHO E NEYMAR JR. ANÁLISE SEMIÓTICO-DISCURSIVA DAS HQS DE MAURÍCIO DE SOUSA

Directory of Open Access Journals (Sweden)

Fábio de Carvalho Messa

2015-08-01

Full Text Available Este artigo apresenta e discute os perfis de três personagens-títulos das histórias em quadrinhos da Turma da Mônica, de Maurício de Sousa – Pelezinho, Ronaldinho Gaúcho e Neymar Jr., craques do futebol brasileiro – para evidenciar as diferentes formas de representação simbólica do futebol no imaginário midiático. A partir de um trabalho metodológico de monitoramento semiótico-discursivo das edições impressas de fevereiro de 2013 a fevereiro de 2014, selecionaramse algumas passagens para destacar as distintas nuances do conhecimento sobre o futebol veiculado nas narrativas, por meio de determinadas ocorrências sígnicas. São elas: características das personalidades dos heróis (sujeitos históricos e suas bases parafrásticas e paródicas; figuratividades do futebol – presença da bola, aspectos sociais e pedagógicos do desporto, propaganda ideológica, estereótipos e índices morais e políticos subjacentes às narrativas. Com base nessa categorização e nas teorias da linguagem de Roland Barthes e Umberto Eco, identificamos que a revista do Pelezinho, proposta mais antiga do autor, concentra no personagem grande parte do repertório cultural do futebol brasileiro dos anos 70-80, condensando questões de linguagem e comportamento, assim como a disseminação dos saberes sobre o futebol e sua pedagogia, incluindo seus desdobramentos afetivos e sociais. Já as histórias de Ronaldinho Gaúcho e Neymar Jr. têm suas propostas encomendadas a partir de temas recorrentes da agenda midiática nacional dos anos 2000, com um menor comprometimento com os saberes acerca do futebol. Por meio de enredos pouco problematizáveis, as políticas editoriais dessas duas últimas tematizam amenidades do universo infantil, engrenam campanhas ideológicas, que reforçam estereótipos e padrões morais, geralmente extraídos da factualidade  jornalística e/ou da mitologia midiático-esportiva brasileira.

Hip-Hop to Health Jr. Randomized Effectiveness Trial: 1-Year Follow-up Results.

Science.gov (United States)

Kong, Angela; Buscemi, Joanna; Stolley, Melinda R; Schiffer, Linda A; Kim, Yoonsang; Braunschweig, Carol L; Gomez-Perez, Sandra L; Blumstein, Lara B; Van Horn, Linda; Dyer, Alan R; Fitzgibbon, Marian L

2016-02-01

The preschool years provide a unique window of opportunity to intervene on obesity-related lifestyle risk factors during the formative years of a child's life. The purpose of this study was to assess the impact of a preschool-based obesity prevention effectiveness trial at 1-year follow-up. RCT. Primarily African American children (aged 3-5 years, N=618) attending Head Start preschool programs administered by Chicago Public Schools. Eighteen preschools were randomly assigned in 2007-2008 to receive either (1) a 14-week teacher-delivered intervention focused on healthy lifestyle behaviors or (2) a 14-week teacher-delivered general health curriculum (control group). The primary outcome, BMI, was measured at baseline, postintervention, and 1-year follow-up. Diet and screen time behaviors were also assessed at these time points. Multilevel mixed effects models were used to test for between-group differences. Data were analyzed in 2014. Significant between-group differences were observed in diet, but not in BMI z-score or screen time at 1-year follow-up. Diet differences favored the intervention arm over controls in overall diet quality (p=0.02) and in subcomponents of diet quality, as measured by the Healthy Eating Index-2005, and in fruit intake (servings/day, excludes juice) (p=0.02). Diet quality worsened more among controls than the intervention group at 1-year follow-up. The adaptation of Hip-Hop to Health Jr. produced modest benefits in diet quality but did not significantly impact weight gain trajectory. Not unlike other effectiveness trials, this real-world version delivered by Head Start teachers produced fewer benefits than the more rigorous efficacy trial. It is important to understand and build upon the lessons learned from these types of trials so that we can design, implement, and disseminate successful evidence-based programs more widely and effectively. This study is registered at www.clinicaltrials.gov NCT00241878. Copyright © 2016 American Journal of

Announcement: New Editor-In-Chief, Robert C. Kennicutt, Jr.

Science.gov (United States)

Abt, Helmut A.

1999-06-01

Effective 1999 July 1, all new manuscripts for Part 1 of The Astrophysical Journal and The Astrophysical Journal Supplement Series should be sent to Dr. Robert C. Kennicutt, Jr., Editor-in-Chief The Astrophysical Journal Steward Observatory University of Arizona Tucson, AZ 85721-0065 The other means of contact are telephone, (520) 621-5145 FAX, (520) 621-5153 and e-mail, apj@as.arizona.edu. For express packages please use the street address of 933 North Cherry Avenue. Dr. Kennicutt will be assisted by several of my loyal coworkers, who will move across the street. Manuscripts received before July 1 will be handled by the current editor until most of their problems have been resolved, at which point the remainder will be sent to Dr. Kennicutt's office. Manuscripts for the Letters should, as before, be sent directly to Dr. Alex Dalgarno at the Center for Astrophysics in Cambridge, MA. We are fortunate that a person with as much experience in research and proven good judgment as Dr. Kennicutt is willing to accept this difficult and time-consuming responsibility. He will be only the seventh Managing Editor or Editor-in-Chief that this Journal has had in its 104 years. Please give him the cooperation and help that you have given the current editor. It has been my privilege to work for 28 years with many of the best astrophysicists in the world and to publish their papers. This was done with the help of the AAS Publications Board and AAS officers, the efforts of Peter Boyce and Evan Owens who made the on-line edition of the Journal possible, three Associate Editors, a score of Scientific Editors, a hardworking staff of six in Tucson, up to 25 production controllers and manuscript editors at the University of Chicago Press, and the thousands of astronomers throughout the world who served as referees. The original masthead called this journal ``An International Review of Spectroscopy and Astronomical Physics.'' That subtitle is no longer appropriate because we do not

Micro-nanocomposites Al2O3/ NbC/ WC and Al2O3/ NbC/ TaC

International Nuclear Information System (INIS)

Santos, Thais da Silva

2014-01-01

Alumina based ceramics belong to a class of materials designated as structural, which are widely used in cutting tools. Although alumina has good properties for application as a structural ceramics, composites with different additives have been produced with the aim of improving its fracture toughness and mechanical strength. New studies point out micro-nanocomposites, wherein the addition of micrometric particles should enhance mechanical strength, and nano-sized particles enhance fracture toughness. In this work, alumina based micro nanocomposites were obtained by including nano-sized NbC and micrometer WC particles at 2:1, 6:4, 10:5 and 15:10 vol% proportions, and also with the inclusion of nano-sized NbC and micrometer TaC particles at 2:1 vol% proportion. For the study of densification, micro-nanocomposites were sintered in a dilatometer with a heating rate of 20°C/min until a temperature of 1800°C in argon atmosphere. Based on the dilatometry results, specimens were sintered in a resistive graphite furnace under argon atmosphere between 1500°C and 1700°C by holding the sintering temperature for 30 minutes. Densities, crystalline phases, hardness and tenacity were determined, and micro-nanocomposites microstructures were analyzed. The samples Al 2 O 3 : NbC: TaC sintered at 1700 ° C achieved the greater apparent density (~ 95% TD) and the sample sintered at 1600 ° C showed homogeneous microstructure and increased hardness value (15.8 GPa) compared to the pure alumina . The compositions with 3% inclusions are the most promising for future applications. (author)

From Catheters To Ventricular Assist Devices: 60 Years of Cardiovascular Experiences With William L. Winters, JR., M.D.

Science.gov (United States)

Winters, W L

2015-01-01

Automatic typewriters, transistor radios, microfiche, black and white television…while considered high-tech in the 1950s, these technologies seem limited when viewed from the 21st century. The same is true for cardiovascular medicine, which back then relied on electrocardiograms and X-rays for most diagnoses. In the 60 years since, advances in medical capabilities have progressed at a staggering pace. Patient research that once required months poring over paper charts is now reduced to hours using electronic medical record databases. Diagnostic images that once took days to process can now be accessed instantly through ultrasound and magnetic resonance imaging. While a half-century ago no one would have imagined accessing any and all information with a 5-second Google search, so too would noninvasive heart surgery been considered unimaginable. Since the 1950s when he graduated from medical school, William L. Winters, Jr., has been a first-hand witness to breathtaking innovations in cardiovascular medicine-both globally and in Houston. Author of Houston Hearts: A History of Cardiovascular Surgery and Medicine at Houston Methodist DeBakey Heart & Vascular Center and long-time medical editor of the Methodist DeBakey Cardiovascular Journal, Dr. Winters sat down with the journal editors this past April to share his insights from the last half-century of medical practice.

Influence of reinforcement weight fraction on microstructure and properties of submicron WC-Co{sub p}/Cu bulk MMCs prepared by direct laser sintering

Energy Technology Data Exchange (ETDEWEB)

Gu, Dongdong [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, 210016 Nanjing (China)]. E-mail: dongdonggu@hotmail.com; Shen, Yifu [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, 210016 Nanjing (China)]. E-mail: yifushen@nuaa.edu.cn

2007-04-04

Direct metal laser sintering (DMLS), due to its flexibility in materials and shapes, exhibits a great potential for fabricating complex shaped bulk metal matrix composites (MMCs). In the present work, the submicron WC-10% Co particulate reinforced Cu matrix composites were prepared using DMLS. The influence of reinforcement content on the sintered densification and the attendant microstructures, e.g. the dispersion homogeneity of the reinforcing particulates and the interfacial bonding ability, was investigated using scanning electron microscopy (SEM), energy disperse X-ray (EDX) spectroscopy, and atomic force microscope (AFM). It shows that using a low reinforcement content of 20 wt.% results in a poor densification with severe balling phenomena, due to a higher average composite coefficient of thermal expansion (CTE) and a superheating of the melt. A heterogeneous microstructure with a significant particulate aggregation is obtained at a high reinforcement content of 40 wt.%, because of a limited liquid formation and the resultant high liquid viscosity and reduced Marangoni effect. Using an optimal reinforcement content of 30 wt.% leads to a uniform distribution of the reinforcing particulates and a compatible interfacial microstructure, so as to obtain a favorable sintered density of 90.3% theoretical density.

Obituary: Leverett Davis, Jr., 1914-2003

Science.gov (United States)

Jokipii, Jack Randolph

2004-12-01

Professor Leverett Davis Jr., Professor of theoretical physics at the California Institute of Technology, died on June 15, 2003 after a long illness. He was 89 years old. He contributed many important ideas and concepts to theoretical astrophysics and was a pioneer in the in situ scientific exploration of space using observations from spacecraft. Davis was born in Elgin, Illinois on March 3, 1914, the eldest of four children of Louis Leverett Davis and Susan Gulick Davis. His parents moved several times as he grew up because his father, a mining engineer, became involved in different mining operations in the American West. Leverett married Victoria Stocker in June 1943. They had two children who died in childhood and subsequently adopted a son, Jeffrey. His wife and son survive him. Davis's early education was rather fractured and uneven because of the many family moves, with periods of home schooling alternating with regular school. His high school education was, on the other hand, reasonably normal. It was while in high school that he decided that he wanted to do physics or mathematics. He went on to earn his Bachelor of Science degree at Oregon State College in 1936, after which he started graduate studies at the California Institute of Technology, to pursue a graduate degree in physics. His advisor was William V. Houston and Davis received his PhD in 1941 for a thesis on electrical properties in nerves. He briefly entertained the idea of changing to work in biophysics. During World War II, Davis became an integral member of the Caltech project for rockets, which developed a number of different types of rockets used in the war. As a result of this war work, Davis wrote a book on Exterior Ballistics, published by Van Nostrand in 1958. He joined the faculty at the California Institute of Technology in 1946, after several years on campus as an instructor. In all, he taught there for nearly four decades before retiring as Professor of Theoretical Physics in 1981

In-situ investigation of laser surface modifications of WC-Co hard metals inside a scanning electron microscope

Science.gov (United States)

Mueller, H.; Wetzig, K.; Schultrich, B.; Pompe, Wolfgang; Chapliev, N. I.; Konov, Vitaly I.; Pimenov, S. M.; Prokhorov, Alexander M.

1989-05-01

The investigation of laser interaction with solid surfaces and of the resulting mechanism of surface modification are of technical interest to optimize technological processes, and they are also of fundamental scientific importance. Most instructive indormation is available with the ail of the in-situ techniques. For instance, measuring of the photon emission of the irradiated surface ane the plasma torch (if it is produced) simultaneously to laser action, makes it possible to gain a global characterization of the laser-solid interaction. In order to obtain additional information about surface and structure modifications in microscopic detail , a laser and scanning electron microscope were combined in to a tandem equipment (LASEM). Inside this eqiipment the microscopic observation is carried out directly at the laser irradiated area without any displacement of the sample. In this way, the stepwise development of surface modification during multipulse irradiation is visible in microscopic details and much more reliable information about the surface modification process is obtainable in comparison to an external laser irradiation. Such kind of equipments were realized simultaneously and independently in the Institut of General Physics (Moscow) and the Central Institute of Solid State Physics and Material Research (Dresden) using a CO2 and a LTd-glass-laser, respectively. In the following the advantages and possibilities of a LASEM shall be demonstrated by some selected investigations of WC-CO hardmeta. The results were obtained in collaboration by both groups with the aid of the pulsed CO2-laser. The TEA CO2 laser was transmitted through a ZnSe-window into the sample chamber of the SEM and focused ofAo tfte sample surface. It was operated in TEM - oo mode with a repetition rate of about 1 pulse per second. A peak power density of about 160 MW/cm2 was achieved in front of the sample surface.

Comparative evaluation of particle properties, formation of reactive oxygen species and genotoxic potential of tungsten carbide based nanoparticles in vitro

Energy Technology Data Exchange (ETDEWEB)

Kuehnel, Dana, E-mail: dana.kuehnel@ufz.de [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Scheffler, Katja [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Department of Cell Techniques and Applied Stem Cell Biology, University of Leipzig, Deutscher Platz 5, 04103 Leipzig (Germany); Wellner, Peggy [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Meissner, Tobias; Potthoff, Annegret [Fraunhofer-Institute for Ceramic Technologies and Systems (IKTS), Winterbergstr. 28, 01277 Dresden (Germany); Busch, Wibke [Department of Bioanalytical Ecotoxicology, Helmholtz-Centre for Environmental Research Leipzig - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Springer, Armin [Centre for Translational Bone, Cartilage and Soft Tissue Research, University Hospital Carl Gustav Carus, Technical University Dresden, Fetscherstrasse 74, 01307 Dresden (Germany); Schirmer, Kristin [Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf (Switzerland); EPF Lausanne, School of Architecture, Civil and Environmental Engineering, 1015 Lausanne (Switzerland); ETH Zuerich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zuerich (Switzerland)

2012-08-15

Highlights: Black-Right-Pointing-Pointer Assessment of toxic potential of tungsten carbide-based nanoparticles. Black-Right-Pointing-Pointer Evaluation of ROS and micronuclei induction of three hard metal nanomaterials. Black-Right-Pointing-Pointer Dependency of observed toxic effects on the materials physical-chemical properties. Black-Right-Pointing-Pointer Differences in several particle properties seem to modulate the biological response. - Abstract: Tungsten carbide (WC) and cobalt (Co) are constituents of hard metals and are used for the production of extremely hard tools. Previous studies have identified greater cytotoxic potential of WC-based nanoparticles if particles contained Co. The aim of this study was to investigate whether the formation of reactive oxygen species (ROS) and micronuclei would help explain the impact on cultured mammalian cells by three different tungsten-based nanoparticles (WC{sub S}, WC{sub L}, WC{sub L}-Co (S: small; L: large)). The selection of particles allowed us to study the influence of particle properties, e.g. surface area, and the presence of Co on the toxicological results. WC{sub S} and WC{sub L}/WC{sub L}-Co differed in their crystalline structure and surface area, whereas WC{sub S}/WC{sub L} and WC{sub L}-Co differed in their cobalt content. WC{sub L} and WC{sub L}-Co showed neither a genotoxic potential nor ROS induction. Contrary to that, WC{sub S} nanoparticles induced the formation of both ROS and micronuclei. CoCl{sub 2} was tested in relevant concentrations and induced no ROS formation, but increased the rate of micronuclei at concentrations exceeding those present in WC{sub L}-Co. In conclusion, ROS and micronuclei formation could not be associated with the presence of Co in the WC-based particles. The contrasting responses elicited by WC{sub S} vs. WC{sub L} appear to be due to large differences in crystalline structure.

A computational study of interfaces in WC–Co cemented carbides

International Nuclear Information System (INIS)

Petisme, Martin V. G.; Johansson, Sven A. E.; Wahnström, Göran

2015-01-01

Interfaces in WC–Co cemented carbides have been investigated using the density functional theory (DFT). Six different model WC/WC grain boundaries are considered, together with the corresponding WC surfaces and WC/Co phase boundaries. The contribution to the grain boundary energies arising from misfit is estimated using an analytical bond order potential (ABOP) and the effect of magnetism is investigated using spinpolarized and non-spinpolarized calculations. A systematic study of adsorption of Co to WC surfaces, Co segregation to WC/WC grain boundaries and Co substitution at WC/Co phase boundaries has been carried out. Adsorption of Co to most WC surfaces is predicted, and result in a monolayer coverage of Co and sometimes a mixed Co/W or Co/W monolayer. The WC surfaces will become prewetted with Co as soon as the atoms become mobile at finite temperatures. Co substitutional segregation is predicted to all model WC/WC grain boundaries in 0.5 monolayer proportion. The segregation of Co to grain boundaries stabilizes the continuous skeleton network of hard WC grains in cemented carbides. Using the obtained interfacial energies, the wetting and the driving force for cobalt grain boundary infiltration are discussed. A dependence on the wetting efficiency on the carbon chemical potential is predicted, which could be an explanation for the better wetting observed experimentally under W-rich conditions. (paper)

Obituary: Benjamin Franklin Peery Jr. (1922-2010)

Science.gov (United States)

Cowley, Charles

2011-12-01

Professor Benjamin F. Peery, Jr. died at his home in Silver Spring, MD of natural causes on 30 November 2010. His full life began in St. Joseph, MO (home of the Pony Express) on 4 March 1922. His father was a railway mail clerk, so his family moved frequently. Most of his childhood was spent in southeastern Minnesota. He enlisted in the army in 1942, and served in campaigns in North Africa and Italy. After his discharge in 1945, he enrolled in the University of Minnesota, earning a BS in Physics in 1949. One of his early hobbies was to build and fly model airplanes. His intention to pursue aeronautical engineering changed to physics, but after receiving a MS in physics from Fisk University in 1955, he decided on a career in astronomy. He told the editors of the PBS series The Astronomers (1991, in which his career is highlighted) he thought it was shamefully absurd not to know what made the stars shine. So he began PhD studies in astronomy at the University of Michigan (Ann Arbor). His dissertation was on the complex eclipsing binary VV Cephei, where a compact hot star passes behind a cool giant star, revealing the structure of that giant's atmosphere. This task was especially demanding because of the complexity of the system's spectrum and the formidable array of observations assembled by Ben's advisor, Dean McLaughlin. Fortunately, Ben's strong physics background enabled him to design and construct one of the first oscilloscope measuring engines, which his fellow students called the PeeryScope. The final (1961) dissertation is an impressive combination of observational and astrophysical analysis. His degree was obtained in 1962; he had already begun a career at the University of Indiana, where he taught and did research (1959--1976). The Indiana years were highly productive. In addition to his own research, he was advisor on six PhD dissertations, and a master's thesis. Several of his students have also had productive careers. An ADS search on his students' names

Obituary: Ralph Robert Robbins, Jr., 1938-2005

Science.gov (United States)

Hemenway, Mary Kay; Jefferys, William H.; Lambert, David L.

2007-12-01

Ralph Robert Robbins, Jr., died on 2 December 2005, in Kyle, Texas. His wife, Maria Elena Robbins, his daughters Julia Robbins Kelso and Stephanie Juarez Balles, his son Matthew Juarez, and five grandchildren survive him. Bob was on the faculty at the University of Texas from 1968 until his retirement in 2003. Bob was born in Wichita, Kansas, on 2 September 1938, the only son of Mildred and Ralph Robert Robbins, Sr. Guided by his high school's policy to provide a practical education to children of working-class parents, Bob began high school with a heavy dose of vocational courses until the results of a test indicated his special talent in mathematics. He was awarded a full scholarship to Yale University, graduating magna cum laude in mathematics in 1960. He won the Warner Prize in Mathematics at Yale that year. He received his Ph.D. in 1966 with a dissertation entitled "The Triplet Spectrum of Neutral Helium in Expanding Nebulae" from the University of California at Berkeley. His interest in college teaching was ignited at this time through summer teaching positions at San Mateo California Junior College and the Ohio State University. Following a year at Texas as a McDonald Observatory Post-doctoral Fellow, Bob taught for a year in the physics department of the University of Houston before returning to the University of Texas at Austin as an Assistant Professor of Astronomy in 1968. He was promoted to Associate Professor in 1972. Bob's research in the early 1970s on theoretical studies of helium was of vital importance to astronomers for over three decades. These pioneering calculations became vital to observational astronomers in the mid-1990s as interest grew in the primordial helium produced by the Big Bang. Bob's interest and influence in education was international in scope. In the summers 1968-1970, he was a government consultant in Mathematics in East Pakistan (now Bangladesh). He consulted with the government that was preparing a master plan for technical

Bacillus sp. JR3 esterase LipJ: A new mesophilic enzyme showing traces of a thermophilic past.

Directory of Open Access Journals (Sweden)

Judit Ribera

Full Text Available A search for extremophile enzymes from ancient volcanic soils in El Hierro Island (Canary Islands, Spain allowed isolation of a microbial sporulated strain collection from which several enzymatic activities were tested. Isolates were obtained after sample cultivation under several conditions of nutrient contents and temperature. Among the bacterial isolates, supernatants from the strain designated JR3 displayed high esterase activity at temperatures ranging from 30 to 100°C, suggesting the presence of at least a hyper-thermophilic extracellular lipase. Sequence alignment of known thermophilic lipases allowed design of degenerated consensus primers for amplification and cloning of the corresponding lipase, named LipJ. However, the cloned enzyme displayed maximum activity at 30°C and pH 7, showing a different profile from that observed in supernatants of the parental strain. Sequence analysis of the cloned protein showed a pentapeptide motif -GHSMG- distinct from that of thermophilic lipases, and much closer to that of esterases. Nevertheless, the 3D structural model of LipJ displayed the same folding as that of thermophilic lipases, suggesting a common evolutionary origin. A phylogenetic study confirmed this possibility, positioning LipJ as a new member of the thermophilic family of bacterial lipases I.5. However, LipJ clusters in a clade close but separated from that of Geobacillus sp. thermophilic lipases. Comprehensive analysis of the cloned enzyme suggests a common origin of LipJ and other bacterial thermophilic lipases, and highlights the most probable divergent evolutionary pathway followed by LipJ, which during the harsh past times would have probably been a thermophilic enzyme, having lost these properties when the environment changed to more benign conditions.

Bacillus sp. JR3 esterase LipJ: A new mesophilic enzyme showing traces of a thermophilic past.

Science.gov (United States)

Ribera, Judit; Estupiñán, Mónica; Fuentes, Alba; Fillat, Amanda; Martínez, Josefina; Diaz, Pilar

2017-01-01

A search for extremophile enzymes from ancient volcanic soils in El Hierro Island (Canary Islands, Spain) allowed isolation of a microbial sporulated strain collection from which several enzymatic activities were tested. Isolates were obtained after sample cultivation under several conditions of nutrient contents and temperature. Among the bacterial isolates, supernatants from the strain designated JR3 displayed high esterase activity at temperatures ranging from 30 to 100°C, suggesting the presence of at least a hyper-thermophilic extracellular lipase. Sequence alignment of known thermophilic lipases allowed design of degenerated consensus primers for amplification and cloning of the corresponding lipase, named LipJ. However, the cloned enzyme displayed maximum activity at 30°C and pH 7, showing a different profile from that observed in supernatants of the parental strain. Sequence analysis of the cloned protein showed a pentapeptide motif -GHSMG- distinct from that of thermophilic lipases, and much closer to that of esterases. Nevertheless, the 3D structural model of LipJ displayed the same folding as that of thermophilic lipases, suggesting a common evolutionary origin. A phylogenetic study confirmed this possibility, positioning LipJ as a new member of the thermophilic family of bacterial lipases I.5. However, LipJ clusters in a clade close but separated from that of Geobacillus sp. thermophilic lipases. Comprehensive analysis of the cloned enzyme suggests a common origin of LipJ and other bacterial thermophilic lipases, and highlights the most probable divergent evolutionary pathway followed by LipJ, which during the harsh past times would have probably been a thermophilic enzyme, having lost these properties when the environment changed to more benign conditions.

Jr Vengateswaran

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 3. Robotics - Instrumentation and Control in Robotics ... Department of Instrumentation and Control Engineering, Regional Engineering College, Tiruchirapalli 620 ...

«An idea unleashed in history»: Dr Martin Luther King Jr and the campaign to end poverty in America

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Robert Hamilton

2018-01-01

Full Text Available As well as being a civil rights advocate, Dr. Martin Luther King Jr consistently called for human rights for all. He opposed poverty, racism, imperialism and political disfranchisement as part of an analysis, which viewed inequality not only in American but also in global terms. In order to address poverty and related human rights issues, King proposed a Poor People’s Campaign (PPC. In May 1968, only weeks after King’s assassination, the PPC saw thousands of poor people travel to Washington DC to protest against poverty. The demonstrators occupied sacred space in the nation’s capital by building a temporary community, known as Resurrection City. During preparations for the PPC and in Washington, the activists drew on a rich legacy of adult education from previous civil rights campaigns. The approaches adopted by PPC participants were innovative and represented alternatives to conventional educational practices. These included Freedom Schools, a Poor People’s University, workshops, marches and demonstrations, which assisted the protesters to come together in coalition to challenge dominant hegemonic narratives concerning the causes, nature and scope of poverty. Although ultimately unsuccessful in its aspiration to end economic injustice in America, the PPC undoubtedly laid the seeds for future anti-poverty activism. The article draws on primary source documents and oral testimonies from five archives.

A community-based obesity prevention program for minority children: rationale and study design for Hip-Hop to Health Jr.

Science.gov (United States)

Fitzgibbon, Marian L; Stolley, Melinda R; Dyer, Alan R; VanHorn, Linda; KauferChristoffel, Katherine

2002-02-01

BACKGROUND; The increasing prevalence of overweight among children in the United States presents a national health priority. Higher rates of overweight/obesity among minority women place their children at increased risk. Although increased rates of overweight are observed in 4- to 5-year-old children, they are not observed in 2- to 3-year-old children. Therefore, early prevention efforts incorporating families are critical. The primary aim of Hip-Hop to Health Jr. is to alter the trajectory toward overweight/obesity among preschool African-American and Latino children. This 5-year randomized intervention is conducted in 24 Head Start programs, where each site is randomized to either a 14-week dietary/physical activity intervention or a general health intervention. This paper presents the rationale and design of the study. Efficacy of the intervention will be determined by weight change for the children and parent/caretaker. Secondary measures include reductions in dietary fat and increases in fiber, fruit/vegetable intake, and physical activity. Baseline data will be presented in future papers. The problem of overweight/obesity is epidemic in the United States. Behaviors related to diet and physical activity are established early in life and modeled by family members. Early intervention efforts addressing the child and family are needed to prevent obesity later in life. This paper describes a comprehensive, family-oriented obesity prevention program for minority preschool children. Copyright 2002 American Health Foundation and Elsevier Science (USA).

Unsedated peroral wireless pH capsule placement vs. standard pH testing: A randomized study and cost analysis

Directory of Open Access Journals (Sweden)

Andrews Christopher N

2012-05-01

Full Text Available Abstract Background Wireless capsule pH-metry (WC is better tolerated than standard nasal pH catheter (SC, but endoscopic placement is expensive. Aims: to confirm that non-endoscopic peroral manometric placement of WC is as effective and better tolerated than SC and to perform a cost analysis of the available esophageal pH-metry methods. Methods Randomized trial at 2 centers. Patients referred for esophageal pH testing were randomly assigned to WC with unsedated peroral placement or SC after esophageal manometry (ESM. Primary outcome was overall discomfort with pH-metry. Costs of 3 different pH-metry strategies were analyzed: 1 ESM + SC, 2 ESM + WC and 3 endoscopically placed WC (EGD + WC using publicly funded health care system perspective. Results 86 patients (mean age 51 ± 2 years, 71% female were enrolled. Overall discomfort score was less in WC than in SC patients (26 ± 4 mm vs 39 ± 4 mm VAS, respectively, p = 0.012 but there were no significant group differences in throat, chest, or overall discomfort during placement. Overall failure rate was 7% in the SC group vs 12% in the WC group (p = 0.71. Per patient costs ($Canadian were $1475 for EGD + WC, $1014 for ESM + WC, and $906 for ESM + SC. Decreasing the failure rate of ESM + WC from 12% to 5% decreased the cost of ESM + WC to $991. The ESM + SC and ESM + WC strategies became equivalent when the cost of the WC device was dropped from $292 to $193. Conclusions Unsedated peroral WC insertion is better tolerated than SC pH-metry both overall and during placement. Although WC is more costly, the extra expense is partially offset when the higher patient and caregiver time costs of SC are considered. Trial registration Clinicaltrials.gov Identifier NCT01364610

Making lemonade from lemons: a case study on loss of space at the Dolph Briscoe, Jr. Library, University of Texas Health Science Center at San Antonio.

Science.gov (United States)

Tobia, Rajia C; Feldman, Jonquil D

2010-01-01

The setting for this case study is the Dolph Briscoe, Jr. Library, University of Texas Health Science Center at San Antonio, a health sciences campus with medical, dental, nursing, health professions, and graduate schools. During 2008-2009, major renovations to the library building were completed including office space for a faculty development department, multipurpose classrooms, a 24/7 study area, study rooms, library staff office space, and an information commons. The impetus for changes to the library building was the decreasing need to house collections in an increasingly electronic environment, the need for office space for other departments, and growth of the student body. About 40% of the library building was remodeled or repurposed, with a loss of approximately 25% of the library's original space. Campus administration proposed changes to the library building, and librarians worked with administration, architects, and construction managers to seek renovation solutions that meshed with the library's educational mission.

Obituary: George Hamilton Bowen Jr. (1925-2009)

Science.gov (United States)

Willson, Lee Anne; Struck, Curtis

2011-12-01

Our colleague and collaborator George Hamilton Bowen, Jr., passed away November 1, 2009 in Ames, Iowa. George was born June 20, 1925 in Tulsa, Oklahoma to George and Dorothy (Huntington) Bowen. He married Marjorie Brown June 19, 1948 in Redondo Beach, California; they had five children, with eight grandchildren and five great-grandchildren at the time of his death. George H. Bowen's third or perhaps his fourth career was in astronomy. He was drafted into the navy in 1944, at the end of his first year as a student at Caltech, and ended his war-time service as an electronic technician on the aircraft carrier Shangri-La. He later said "In just nine months, starting from scratch (Ohm's law!), we learned an amazing amount - not by memorization, of course, but by study and real understanding of the basic function of the most advanced AC circuits then being used for instrumentation, measurements, communications, control systems, and much more." He gained a confidence that he could quickly and accurately diagnose and solve technical problems that stood him well in future work. One accomplishment he took particular pride in was figuring out how the radar control used cams and gears to solve the trigonometry for accurate pointing. He also described how the captain was alarmed when weather conditions changed so that refraction no longer showed them distant, small boats around the curvature of Earth. After the war, George Bowen returned to undergraduate and eventually graduate study at Caltech, where he was recruited to the biophysics research group headed by future Nobel Laureate Max Delbrück. George often described his joy in working with these first-rate scientists and finding himself accepted as a part of the effort. He finished his BS with honors in 1949 and his PhD in 1953 with a thesis on "Kinetic Studies on the Mechanism of Photoreactivation of Bacteriophase T2 Inactivated by Ultraviolet Light" involving work with E Coli. This work was supported by grants from the U

CVD coating of alumina film of CW-[Beta]t-Co cemented carbide by using hydrogen sulphide contained atmosphere. Ryuka suiso wo fukumu CVD fun'iki wo mochiite no WC-[Beta]t-Co choko gokinjo eno Al2O3 hifuku

Energy Technology Data Exchange (ETDEWEB)

Ueki, M.; Kodama, H. (Toshiba Tungaloy Co. Ltd., Kawasaki (Japan)); Suzuki, H. (Chiba Institute of Technology, Chiba (Japan). Faculty of Engineering)

1994-06-15

For the purpose of forming Al2O3, a hard material, of uniform thickness on an ultrahard alloy as base material, addition of H2S gas to the reaction gas was investigated. WC-9 mass% [beta]t-7 mass%Co ([beta]t is a solid solution of 22%Ti, 33%TaC and 45%WC) as base body was covered with TiC, TiN, and Al2O3 successively. At the time of CVD coating of Al2O3, H2S of 0-0.84 vol% was added to the reaction gas (H2 gas containing 2.3%AlCl3 and 2.8%CO2). As the results, the following information was obtained: Thickness (A) of Al2O3 in the edge section and that (B) in the fiat section respectively increase with the addition of H2S of up to 0.3% while A/B decreases in this range of H2S concentration and levels off above 0.3%. And the growth rate of Al2O3 increases with addition of H2S. This fact may be attributed to the reason that H2S is a catalyst of forming H2O in the reaction gas. A possible reason of decrease of A/B is that the S content in Al2O3 is larger in the edge section than in the flat section. The addition of H2S transforms the Al2O3 film to coarse columnar crystals and tends to lower the strength of the film and weaken its contact to the ground. 5 refs., 5 figs.

A novel scheme for the validation of an automated classification method for epileptic spikes by comparison with multiple observers.

Science.gov (United States)

Sharma, Niraj K; Pedreira, Carlos; Centeno, Maria; Chaudhary, Umair J; Wehner, Tim; França, Lucas G S; Yadee, Tinonkorn; Murta, Teresa; Leite, Marco; Vos, Sjoerd B; Ourselin, Sebastien; Diehl, Beate; Lemieux, Louis

2017-07-01

To validate the application of an automated neuronal spike classification algorithm, Wave_clus (WC), on interictal epileptiform discharges (IED) obtained from human intracranial EEG (icEEG) data. Five 10-min segments of icEEG recorded in 5 patients were used. WC and three expert EEG reviewers independently classified one hundred IED events into IED classes or non-IEDs. First, we determined whether WC-human agreement variability falls within inter-reviewer agreement variability by calculating the variation of information for each classifier pair and quantifying the overlap between all WC-reviewer and all reviewer-reviewer pairs. Second, we compared WC and EEG reviewers' spike identification and individual spike class labels visually and quantitatively. The overlap between all WC-human pairs and all human pairs was >80% for 3/5 patients and >58% for the other 2 patients demonstrating WC falling within inter-human variation. The average sensitivity of spike marking for WC was 91% and >87% for all three EEG reviewers. Finally, there was a strong visual and quantitative similarity between WC and EEG reviewers. WC performance is indistinguishable to that of EEG reviewers' suggesting it could be a valid clinical tool for the assessment of IEDs. WC can be used to provide quantitative analysis of epileptic spikes. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Synergistic effect of tungsten carbide and palladium on graphene for promoted ethanol electrooxidation.

Science.gov (United States)

Yang, Jun; Xie, Ying; Wang, Ruihong; Jiang, Baojiang; Tian, Chungui; Mu, Guang; Yin, Jie; Wang, Bo; Fu, Honggang

2013-07-24

The synergistic effect of WC and Pd has large benefit for ethanol electrooxidation. The small-sized Pd nanoparticles (NPs) decorated tungsten carbide on graphene (Pd-WC/GN) will be a promising anode catalyst for the direct ethanol fuel cells. The density functional theory (DFT) calculations reveal that the strong interaction exists at the interface between Pd and WC, which induces the electron transfer from WC to Pd. Fortunately, the nanoscale architecture of Pd-WC/GN has been successfully fabricated in our experiments. X-ray photoelectron spectrum further confirms the existence of electron transfer from WC to Pd in a Pd-WC/GN nanohybrid. Notably, electrochemical tests show that the Pd-WC/GN catalyst exhibits low onset potential, a large electrochemical surface area, high activity, and stability for ethanol electrooxidation in alkaline solution compared with Pd/graphene and Pd/commercial Vulcan 72R carbon catalysts. The enhancement can be attributed to the synergistic effect of Pd and WC on graphene. At the interface between Pd and WC, the electron transfer from WC to Pd leads to the increased electron densities of surface Pd, which is available for weakening adsorption of intermediate oxygen-containing species such as CO and activating catalyst. Meanwhile, the increased tungsten oxide induced by electron transfer can facilitate the effective removal of intermediate species adsorbed on the Pd surface through a bifunctional mechanism or hydrogen spillover effect.

Gender-assortative waist circumference in mother-daughter and father-son pairs, and its implications. An 11-year longitudinal study in children (EarlyBird 59).

Science.gov (United States)

Mostazir, M; Jeffery, A; Voss, L; Wilkin, T

2014-06-01

Body mass index (BMI) is reportedly gender assortative (mother-daughter, father-son) in contemporary children. We investigated the corresponding transmission of waist circumference (WC) and its implications. We measured parental WC at baseline and WC, height, weight and para-umbilical skin-fold (USF) annually in their offspring from 5 to 15 years (n = 223 trios). Parents were deemed normal metabolic risk (NR) or high risk (HR) according to World Health Organization (WHO) cut-points for WC (mothers 80 cm, fathers 94 cm). The residual from WC adjusted for BMI (WC|BMI ) was used as a surrogate for excess intra-abdominal fat, and its association with insulin resistance (HOMA2-IR) was sought. WC and USF were both gender assortative, while WC|BMI was not. WC was greater by 1.62 cm (P mothers, and by 1.32 cm (P surrogate in this analysis) is unrelated to parental waist circumference, but metabolically harmful. © 2013 The Authors. Pediatric Obesity © 2013 International Association for the Study of Obesity.

8-13 μm spectra of very late type Wolf-Rayet stars

International Nuclear Information System (INIS)

Aitken, D.K.; Barlow, M.J.; Roche, P.F.; Spenser, P.M.

1980-01-01

8 to 13 μm spectra are presented of the late Wolf-Rayet stars, Ve 2-45 (WC9), CRL 2104 (WC8), He 2-113 (WC10) and CPD-56 0 8032 (WC10). Both WC10 stars show the unidentified feature at 11.25 μm and one of them that at 8.6 μm; their spectra resemble those of some planetary nebulae. These features are absent in the WC8/9 stars, whose spectra, together with their infrared photometric data, can be understood in terms of approximately 900 K blackbody spectra subject to some interstellar silicate absorption and with a small excess beyond 10 μm, perhaps due to SiC grains. The WC10 objects are characterized by much lower dust temperatures and their evolutionary status appears to be very different from that of the WC8/9 stars. (author)

Size-dependent effects of tungsten carbide-cobalt particles on oxygen radical production and activation of cell signaling pathways in murine epidermal cells

International Nuclear Information System (INIS)

Ding, M.; Kisin, E.R.; Zhao, J.; Bowman, L.; Lu, Y.; Jiang, B.; Leonard, S.; Vallyathan, V.; Castranova, V.; Murray, A.R.; Fadeel, B.; Shvedova, A.A.

2009-01-01

Hard metal or cemented carbide consists of a mixture of tungsten carbide (WC) (85%) and metallic cobalt (Co) (5-15%). WC-Co is considered to be potentially carcinogenic to humans. However, no comparison of the adverse effects of nano-sized WC-Co particles is available to date. In the present study, we compared the ability of nano- and fine-sized WC-Co particles to form free radicals and propensity to activate the transcription factors, AP-1 and NF-κB, along with stimulation of mitogen-activated protein kinase (MAPK) signaling pathways in a mouse epidermal cell line (JB6 P + ). Our results demonstrated that nano-WC-Co generated a higher level of hydroxyl radicals, induced greater oxidative stress, as evidenced by a decrease of GSH levels, and caused faster JB6 P + cell growth/proliferation than observed after exposure of cells to fine WC-Co. In addition, nano-WC-Co activated AP-1 and NF-κB more efficiently in JB6 +/+ cells as compared to fine WC-Co. Experiments using AP-1-luciferase reporter transgenic mice confirmed the activation of AP-1 by nano-WC-Co. Nano- and fine-sized WC-Co particles also stimulated MAPKs, including ERKs, p38, and JNKs with significantly higher potency of nano-WC-Co. Finally, co-incubation of the JB6 +/+ cells with N-acetyl-cysteine decreased AP-1 activation and phosphorylation of ERKs, p38 kinase, and JNKs, thus suggesting that oxidative stress is involved in WC-Co-induced toxicity and AP-1 activation.

Tungsten carbide/porous carbon composite as superior support for platinum catalyst toward methanol electro-oxidation

International Nuclear Information System (INIS)

Jiang, Liming; Fu, Honggang; Wang, Lei; Mu, Guang; Jiang, Baojiang; Zhou, Wei; Wang, Ruihong

2014-01-01

Graphical abstract: The WC nanoparticles are well dispersed in the carbon matrix. The size of WC nanoparticles is about 30 nm. It can be concluded that tungsten carbide and carbon composite was successfully prepared by the present synthesis conditions. - Highlights: • The WC/PC composite with high specific surface area was prepared by a simple way. • The Pt/WC/PC catalyst has superior performance toward methanol electro-oxidation. • The current density for methanol electro-oxidation is as high as 595.93 A g −1 Pt. • The Pt/WC/PC catalyst shows better durability and stronger CO electro-oxidation. • The performance of Pt/WC/PC is superior to the commercial Pt/C (JM) catalyst. - Abstract: Tungsten carbide/porous carbon (WC/PC) composites have been successfully synthesized through a surfactant assisted evaporation-induced-assembly method, followed by a thermal treatment process. In particular, WC/PC-35-1000 composite with tungsten content of 35% synthesized at the carbonized temperature of 1000 °C, exhibited a specific surface area (S BET ) of 457.92 m 2 g −1 . After loading Pt nanoparticles (NPs), the obtained Pt/WC/PC-35-1000 catalyst exhibits the highest unit mass electroactivity (595.93 A g −1 Pt) toward methanol electro-oxidation, which is about 2.6 times as that of the commercial Pt/C (JM) catalyst. Furthermore, the Pt/WC/PC-35-1000 catalyst displays much stronger resistance to CO poisoning and better durability toward methanol electrooxidation compared with the commercial Pt/C (JM) catalyst. The high electrocatalytic activity, strong poison-resistivity and good stability of Pt/WC/PC-35-1000 catalyst are attributed to the porous structures and high specific surface area of WC/PC support could facilitate the rapid mass transportation. Moreover, synergistic effect between WC and Pt NPs is favorable to the higher catalytic performance

Childhood central adiposity at ages 5 and 9 shows consistent relationship with that of the maternal grandmother but not other grandparents.

Science.gov (United States)

Somerville, R; Khalil, H; Segurado, R; Mehegan, J; Viljoen, K; Heinen, M; Murrin, C; Kelleher, C C

2018-05-09

The importance of a life course approach to childhood obesity has been emphasized; however, few studies can prospectively investigate relationships in three-generation families. To prospectively investigate the relationship between grandparental and grandchild waist circumference (WC) at ages 5 and 9 down maternal and paternal lines. At baseline in the Lifeways Cross-Generation Cohort, 1094 children were born to 1082 mothers; 585 were examined at age 5 and 298 at age 9. Of the total 589 children with measured WC, data were also available from 745 grandparents. Child WC was standardized for age and sex, and theory-based hierarchical linear regression was used. Maternal grandmother (MGM) WC was predictive of grandchild WC at both time points. At age 5, grandchild's standardized birth weight (B = 0.266, p = 0.001), mother's means tested eligibility for free medical care (B = 1.029, p = 0.001) and grandchild seeing maternal grandparents daily (B = 0.312, p = 0.048) were significant alongside MGM WC (B = 0.015, p = 0.019). At age 9, only MGM WC (B = 0.022, p = 0.033) and mother's WC (B = 0.032, p = 0.005) were significant. Mediation analysis with mother's WC showed significant direct relationship of MGM and grandchild WC. This prospective cross-generational cohort shows consistent patterns of association between MGM and grandchild WC, not seen in other grandparental lineages. © 2018 World Obesity Federation.

SEM and EBSD characterization of bi-layered functionally graded hard metal composites; REM- und EBSD-Charakterisierung von zweischichtigen, funktionell abgestuften Metallverbundwerkstoffen

Energy Technology Data Exchange (ETDEWEB)

Prat, Orlando; Sanhueza, Felipe [Univ. de Concepcion (Chile). Dept. de Ingenieria de Materiales; Suarez, Sebastian [Saarland Univ., Saarbruecken (Germany). Chair of Functional Materials; Garcia, Jose [AB Sandvik Coromant R and D, Stockholm (Sweden)

2016-11-15

WC-Co bi-layer functionally graded composites were produced by powder metallurgy techniques. The influence of WC particle size and the grain growth inhibitor on the formation of the functionally graded composite was investigated. SEM images show that all sintered samples present a graded microstructure after sintering, with two side regions of extra-coarse and coarse WC-Co and a clear, dense interface without defects or other phases. EBSD results showed a change of WC particle size depending on the processing and the addition of Mo{sub 2}C. Cobalt binder distribution corresponds to WC particle size. Hardness values correlate to WC particle size and binder content. It is shown that tailored hardness/toughness can be produced by adjusting the WC particle size and binder content on both sides of the bi-layer composite.

Dynamic Characterization of a Low Cost Microwave Water-Cut Sensor in a Flow Loop

KAUST Repository

Karimi, Muhammad Akram

2017-03-31

Inline precise measurement of water fraction in oil (i.e. water-cut [WC]) finds numerous applications in oil and gas industry. This paper presents the characterization of an extremely low cost, completely non-intrusive and full range microwave water-cut sensor based upon pipe conformable microwave T-resonator. A 10″ microwave stub based T-resonator has been implemented directly on the pipe surface whose resonance frequency changes in the frequency band of 90MHz–190MHz (111%) with changing water fraction in oil. The designed sensor is capable of detecting even small changes in WC with a resolution of 0.07% at low WC and 0.5% WC at high WC. The performance of the microwave WC sensor has been tested in an in-house flow loop. The proposed WC sensor has been characterized over full water-cut range (0%–100%) not only in vertical but also in horizontal orientation. The sensor has shown predictable response in both orientations with huge frequency shift. Moreover, flow rate effect has also been investigated on the proposed WC sensor’s performance and it has been found that the sensor’s repeatability is within 2.5% WC for variable flow rates.

78 FR 15014 - Change in Bank Control Notices; Acquisitions of Shares of a Bank or Bank Holding Company

Science.gov (United States)

2013-03-08

... Meyer, Jr., individually and as trustee of the: ACM, Jr. 2010 3Y GRAT A, the ACM, Jr. 2010 3Y GRAT B, the ACM, Jr. 2010 3Y GRAT C, the ACM, Jr. 2013 2Y GRAT A, the ACM, Jr. 2013 2Y GRAT B, the ACM, Jr. 2013 2Y GRAT C, the ACM, Jr. 2013 2Y GRAT D, the Katharine Clara Kimmel Non- Exempt Trust C/U Elisabeth...

A dust shell around the early-type Wolf-Ryate star WR 19

International Nuclear Information System (INIS)

Williams, P.M.; Hucht, K.A. van der; Bouchet, P.

1990-01-01

Infrared photometry of the WC4-type Wolf-Rayet star WR 19 (LS 3) in 1988-90 shows evidence for an expanding dust shell in its wind, similar to those observed from late-type WR stars like WR 48a (WC8), WR 140 (WC7+04) and WR 137 (WC7+). This demonstrates that dust formation by Wolf-Rayet stars is not restricted to later WC subtypes and is more common than hitherto supposed. (author)

Liquid agents for dispersion of hard alloys

International Nuclear Information System (INIS)

Putintseva, M.N.

2006-01-01

Effects of dispersant properties on granulometric, chemical, and phase composition of the products of WC hard alloy electroerosion are considered. It is established that an increase of liquid dispersant permittivity results in enhanced powder dispersity, and an increase of boiling temperature and kinematic viscosity of a hydrocarbon liquid promotes a carbon loss from WC and intensifies pyrolysis of the liquid.On electroerosion of WC base hard alloy in oil a powder particle consists of b-WC+W 2 C phases, in kerosine - of a-WC+b-WC, in distilled water - of W+W 2 C. The viscosity of liquid dispersants practically has no effect on powder particle size [ru

Waist Circumference Adjusted for Body Mass Index and Intra-Abdominal Fat Mass

Science.gov (United States)

Berentzen, Tina Landsvig; Ängquist, Lars; Kotronen, Anna; Borra, Ronald; Yki-Järvinen, Hannele; Iozzo, Patricia; Parkkola, Riitta; Nuutila, Pirjo; Ross, Robert; Allison, David B.; Heymsfield, Steven B.; Overvad, Kim; Sørensen, Thorkild I. A.; Jakobsen, Marianne Uhre

2012-01-01

Background The association between waist circumference (WC) and mortality is particularly strong and direct when adjusted for body mass index (BMI). One conceivable explanation for this association is that WC adjusted for BMI is a better predictor of the presumably most harmful intra-abdominal fat mass (IAFM) than WC alone. We studied the prediction of abdominal subcutaneous fat mass (ASFM) and IAFM by WC alone and by addition of BMI as an explanatory factor. Methodology/Principal Findings WC, BMI and magnetic resonance imaging data from 742 men and women who participated in clinical studies in Canada and Finland were pooled. Total adjusted squared multiple correlation coefficients (R2) of ASFM and IAFM were calculated from multiple linear regression models with WC and BMI as explanatory variables. Mean BMI and WC of the participants in the pooled sample were 30 kg/m2 and 102 cm, respectively. WC explained 29% of the variance in ASFM and 51% of the variance in IAFM. Addition of BMI to WC added 28% to the variance explained in ASFM, but only 1% to the variance explained in IAFM. Results in subgroups stratified by study center, sex, age, obesity level and type 2 diabetes status were not systematically different. Conclusion/Significance The prediction of IAFM by WC is not improved by addition of BMI. PMID:22384179

Comprehensive Screening of Some West and Central African Sesame Genotypes for Drought Resistance Probing by Agromorphological, Physiological, Biochemical and Seed Quality Traits

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Komivi Dossa

2017-12-01

Full Text Available Sesame is an important crop in West and Central Africa playing a role of an alternative cash crop for smallholders. However, sesame productivity is highly impaired by drought. This study aimed at identifying some drought-resistant genotypes and efficient screening traits in large sesame germplasm. Ten genotypes were examined based on 21 biochemical, physiological, agromorphological and seed quality traits under three weeks of water stress. A high variability for drought resistance was observed among the genotypes. The genotypes WC17, WC18 and WC14 were drought resistant, WC12, WC13, WC06 and WC03 were moderately drought resistant while, WC02, WC10 and WC08 were drought sensitive, based on principal component analysis. The resistant genotypes exhibited both avoidance and tolerance features including increase of the root system, reduced water loss, highest activity of antioxidative enzymes and accumulation of proline. They produced higher biomass and had higher ability to maintain seed quality under drought stress compared with the sensitive genotypes. Strong accumulation (~200% ratio stress/control of biochemical markers including superoxide dismutase, ascorbate peroxidase, catalase and proline could be regarded as an important indicator for selecting drought resistant genotypes. This study represents a reference for future research towards developing new varieties with improved drought resistance in West and Central Africa.

Obituary: Richard L. (Dick) Walker, Jr., 1938-2005

Science.gov (United States)

Pier, Jeffrey R.; Mason, Brian

2005-12-01

Koch Center for Science, Math, and Technology at Deerfield Academy in Massachusetts. He also consulted with James Turrell, providing astronomical position information for the design of the Roden Crater Project outside of Flagstaff. While he will be remembered for his significant scientific contributions to the field of astronomy, those who knew Dick, both scientists and non-scientists alike, will probably remember him best for his humility, his humanity, and his loyal and abiding friendship. He was a man with a terrific sense of humor and an infectious laugh. It was always an honor and pleasure to be in his company. Richard L. Walker, Jr. is survived by his wife, Patricia, two daughters from his first marriage: Brenda Walker of Las Vegas, NV, and Pamela Hepburn of Holland, OH, as well as four children from Patricia's first marriage: Doug Browning of Lake Havasu City, AZ, Michael Browning of Kingman, AZ, Kim Bructo of Orient, OH, and Jennifer Brown of Lake Havasu City, AZ. He is also survived by ten grandchildren and three great-grandchildren. He was preceded in death by his father Richard, mother Mary, and daughter, Paula Jean Elizabeth Stone.

[The relevance of junctional rhythm during neurocardiogenic reaction provoked by tilt testing].

Science.gov (United States)

Zyśko, Dorota; Gajek, Jacek; Agrawal, Anil Kumar; Rudnicki, Jerzy

2012-01-01

During neurocardiogenic reaction provoked by tilt testing (TT), different arrhythmias such as sinus bradycardia, sinus arrest, atrioventricular block or junctional rhythm or beats (JR) may occur. The characteristics of the JR during neurocardiogenic reaction have not yet been systematically assessed. It is not known whether the presence of JR during neurocardiogenic reaction is related to clinical characteristics of syncopal patients or the outcome of TT. To assess whether clinical outcome of TT and clinical data are related to the presence of JR during TT. The study group consisted of 532 patients aged 43.3 ± 18.2 years with positive TT, divided into four groups on the basis of the presence of JR and/or a ventricular pause (VP) during neurocardiogenic reaction: group VP(-)/JR(+) - JR present and VP absent, group VP(+)/JR(+) - both JR and VP present, group VP(+)/JR(-) - JR absent and VP present, and group VP(-)/JR(-) - both JR and VP absent. The control group consisted of 53 patients with no history of syncope or presyncope, including 46 patients with negative TT and seven patients with false positive TT. Total loss of consciousness during TT occurred in group VP(-)/JR(+) less frequently than in groups VP(+)/JR(+) and VP(+)/JR(-), and more frequently than in group VP(-)/JR(-) (80% vs 96% vs 94% vs 62%; p 〈 0.05 for both comparisons). Group VP(-)/JR(+) was significantly younger than group VP(-)/JR(-) (37.3 ± 16.3 years vs 45.8 ± 18.9 years; p 〈 0.05) and had a lower number of syncopal events than group VP(+)/JR(+) and VP(+)/JR(-) (median [IQ]: 2.5 (1-6) vs 4 (2-12) and 4 (2-10), respectively; p 〈 0.05) and lower rate of traumatic injuries than group VP(+)/JR(+) and VP(+)/JR(-) (22% vs 45% and 39%, respectively; p 〈 0.05). Logistic regression analysis revealed that the presence of JR was associated with younger age, male gender, history of blood-instrumentation-injection phobia and higher number of syncopal spells in medical history. The ROC curve analysis

Tungsten carbide/porous carbon composite as superior support for platinum catalyst toward methanol electro-oxidation

Energy Technology Data Exchange (ETDEWEB)

Jiang, Liming [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Fu, Honggang, E-mail: fuhg@vip.sina.com [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Functional Inorganic Material Chemistry, Heilongjiang University, Harbin 150080 (China); Wang, Lei; Mu, Guang; Jiang, Baojiang; Zhou, Wei; Wang, Ruihong [Key Laboratory of Functional Inorganic Material Chemistry, Heilongjiang University, Harbin 150080 (China)

2014-01-01

Graphical abstract: The WC nanoparticles are well dispersed in the carbon matrix. The size of WC nanoparticles is about 30 nm. It can be concluded that tungsten carbide and carbon composite was successfully prepared by the present synthesis conditions. - Highlights: • The WC/PC composite with high specific surface area was prepared by a simple way. • The Pt/WC/PC catalyst has superior performance toward methanol electro-oxidation. • The current density for methanol electro-oxidation is as high as 595.93 A g{sup −1} Pt. • The Pt/WC/PC catalyst shows better durability and stronger CO electro-oxidation. • The performance of Pt/WC/PC is superior to the commercial Pt/C (JM) catalyst. - Abstract: Tungsten carbide/porous carbon (WC/PC) composites have been successfully synthesized through a surfactant assisted evaporation-induced-assembly method, followed by a thermal treatment process. In particular, WC/PC-35-1000 composite with tungsten content of 35% synthesized at the carbonized temperature of 1000 °C, exhibited a specific surface area (S{sub BET}) of 457.92 m{sup 2} g{sup −1}. After loading Pt nanoparticles (NPs), the obtained Pt/WC/PC-35-1000 catalyst exhibits the highest unit mass electroactivity (595.93 A g{sup −1} Pt) toward methanol electro-oxidation, which is about 2.6 times as that of the commercial Pt/C (JM) catalyst. Furthermore, the Pt/WC/PC-35-1000 catalyst displays much stronger resistance to CO poisoning and better durability toward methanol electrooxidation compared with the commercial Pt/C (JM) catalyst. The high electrocatalytic activity, strong poison-resistivity and good stability of Pt/WC/PC-35-1000 catalyst are attributed to the porous structures and high specific surface area of WC/PC support could facilitate the rapid mass transportation. Moreover, synergistic effect between WC and Pt NPs is favorable to the higher catalytic performance.

Fedmerelatererede sundhedsomkostninger vurderet ud fra måling af enten BMI eller taljeomkreds--sekundaerpublikation

DEFF Research Database (Denmark)

Højgaard, Betina; Olsen, Kim Rose; Søgaard, Jes

2009-01-01

circumference (WC) and body mass index (BMI). The analyses show that the combination of BMI and WC does not improve the identification of high-risk individuals compared with the use of WC alone. The health service costs increase by 1.24% in women and 2.08% in men pr. cm increase in WC above the normal range....

Fedmerelatererede sundhedsomkostninger vurderet ud fra måling af enten BMI eller taljeomkreds--sekundaerpublikation

DEFF Research Database (Denmark)

Højgaard, Betina; Olsen, Kim Rose; Søgaard, Jes

2009-01-01

circumference (WC) and body mass index (BMI). The analyses show that the combination of BMI and WC does not improve the identification of high-risk individuals compared with the use of WC alone. The health service costs increase by 1.24% in women and 2.08% in men pr. cm increase in WC above the normal range...

The relationship of waist circumference and body mass index to grey matter volume in community dwelling adults with mild obesity.

Science.gov (United States)

Hayakawa, Y K; Sasaki, H; Takao, H; Yoshikawa, T; Hayashi, N; Mori, H; Kunimatsu, A; Aoki, S; Ohtomo, K

2018-02-01

Previous work has shown that high body mass index (BMI) is associated with low grey matter volume. However, evidence on the relationship between waist circumference (WC) and brain volume is relatively scarce. Moreover, the influence of mild obesity (as indexed by WC and BMI) on brain volume remains unclear. This study explored the relationships between WC and BMI and grey matter volume in a large sample of Japanese adults. The participants were 792 community-dwelling adults (523 men and 269 women). Brain magnetic resonance images were collected, and the correlation between WC or BMI and global grey matter volume were analysed. The relationships between WC or BMI and regional grey matter volume were also investigated using voxel-based morphometry. Global grey matter volume was not correlated with WC or BMI. Voxel-based morphometry analysis revealed significant negative correlations between both WC and BMI and regional grey matter volume. The areas correlated with each index were more widespread in men than in women. In women, the total area of the regions significantly correlated with WC was slightly greater than that of the regions significantly correlated with BMI. Results show that both WC and BMI were inversely related to regional grey matter volume, even in Japanese adults with somewhat mild obesity. Especially in populations with less obesity, such as the female participants in current study, WC may be more sensitive than BMI as a marker of grey matter volume differences associated with obesity.

Obesity phenotype and coronary heart disease risk as estimated by the Framingham risk score.

Science.gov (United States)

Park, Yong Soon; Kim, Jun-Su

2012-03-01

There are conflicting data as to whether general or abdominal obesity is a better predictor of cardiovascular risk. This cross-sectional study involved 4,573 subjects aged 30 to 74 yr who participated in the Fourth Korea National Health and Nutrition Examination Survey conducted in 2008. Obesity phenotype was classified by means of body mass index (BMI) and waist circumference (WC), and participants were categorized into 4 groups. Individuals' 10-yr risk of coronary heart diseases (CHD) was determined from the Framingham risk score. Subjects with obese WC had a higher proportion of high risk for CHD compared to the normal WC group, irrespective of BMI level. Relative to subjects with normal BMI/normal WC, the adjusted odds ratios (ORs) of normal BMI/obese WC group (OR 2.93 [1.70, 5.04] and OR 3.10 [1.49, 6.46]) for CHD risk in male were higher than obese BMI/obese WC group (OR 1.91 [1.40, 2.61] and OR 1.70 [1.16, 2.47]), whereas the adjusted ORs of obese BMI/obese WC group (OR 1.94 [1.24, 3.04] and OR 3.92 [1.75, 8.78]) were higher than the others in female. Subjects with obese BMI/normal WC were not significantly associated with 10-yr CHD risk in men (P = 0.449 and P = 0.067) and women (P = 0.702 and P = 0.658). WC is associated with increased CHD risk regardless of the level of BMI. Men with normal BMI and obese WC tend to be associated with CHD risk than those with obese BMI and obese WC.

Intensified association between waist circumference and hypertension in abdominally overweight children.

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Dong, Bin; Wang, Zhiqiang; Yang, Yide; Wang, Hai-Jun; Ma, Jun

2016-01-01

Abdominal adiposity is an important risk factor for childhood hypertension. The present study aimed to compare the strength of the association between waist circumference (WC) and hypertension in children with different WC levels. A total of 82,413 Chinese children aged 9-17 years were selected. An abdominally overweight child was defined as a child with WC ≥75th sex- and age-specific percentile. Hypertension was categorised as ≥95th sex-, age- and height-specific percentile. Logistic regression model was applied to calculate the odds ratio (OR) and 95% confidence interval (CI) of WC for hypertension after WC was transformed into sex- and age-specific z-score. Abdominally overweight children presented a higher risk of hypertension (OR: 2.39; 95% CI: 2.26, 2.54) than children with normal WC. In children with normal WC, one sex- and age-specific standard deviation increase in WC was associated with a 42% increase in odds of hypertension (OR: 1.42; 95% CI: 1.30, 1.55). That increase was elevated to 74% in abdominally overweight children (OR: 1.74; 95% CI: 1.66, 1.82). A similar pattern was also observed in different sex and area groups, and in children 9-14 years old. An intensified association between WC and hypertension was observed in abdominally overweight Chinese children. The gain in WC was associated with greater increase in hypertensive risk in abdominally overweight children than that of children with normal WC. These findings could improve intervention strategies for hypertension risk reduction in children. Copyright © 2015 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

The effectiveness of insurer-supported safety and health engineering controls in reducing workers' compensation claims and costs.

Science.gov (United States)

Wurzelbacher, Steven J; Bertke, Stephen J; Lampl, Michael P; Bushnell, P Timothy; Meyers, Alysha R; Robins, David C; Al-Tarawneh, Ibraheem S

2014-12-01

This study evaluated the effectiveness of a program in which a workers' compensation (WC) insurer provided matching funds to insured employers to implement safety/health engineering controls. Pre- and post-intervention WC metrics were compiled for the employees designated as affected by the interventions within 468 employers for interventions occurring from 2003 to 2009. Poisson, two-part, and linear regression models with repeated measures were used to evaluate differences in pre- and post-data, controlling for time trends independent of the interventions. For affected employees, total WC claim frequency rates (both medical-only and lost-time claims) decreased 66%, lost-time WC claim frequency rates decreased 78%, WC paid cost per employee decreased 81%, and WC geometric mean paid claim cost decreased 30% post-intervention. Reductions varied by employer size, specific industry, and intervention type. The insurer-supported safety/health engineering control program was effective in reducing WC claims and costs for affected employees. © 2014 Wiley Periodicals, Inc.

Macronutrients Association with Change in Waist and Hip Circumference Over 9 Years.

Science.gov (United States)

Lofley, Amy C; Root, Martin M

2017-01-01

The calorie distribution of macronutrients affects individuals' health. Quantity and source of macronutrients may play major roles in waist circumference (WC) and hip circumference (HC). This study's purpose is to investigate the association between the quantity and source of macronutrients and the change in WC and HC over 9 years. Participants (N = 11,343) were from the Atherosclerosis Risk in Community Study. Those diagnosed with cancer or a decrease in WC or HC of 15 cm or more over 9 years were excluded. Change scores were created for anthropometrics between clinic visits over 9 years. Macronutrient intakes were assessed by a food frequency questionnaire at visit 1 and presented as a percentage of energy intake. Linear regressions were performed with quartiles of dietary components on change scores for WC and HC with controlling cofactors. Gender subgroup analysis was performed. A larger increase in WC was associated with higher intakes of total carbohydrates, dietary fiber, and fructose (p for trend Macronutrient source and quantity play a significant role in individuals' adiposity and effects on WC and HC. Overall, an increase in WC and HC was seen over the 11 years. The source and quantity of the macronutrients play a significant role in WC and HC. Further research needs to be conducted to see the exact effect that macronutrients play on WC and HC.

Predicting waist circumference from body mass index.

Science.gov (United States)

Bozeman, Samuel R; Hoaglin, David C; Burton, Tanya M; Pashos, Chris L; Ben-Joseph, Rami H; Hollenbeak, Christopher S

2012-08-03

Being overweight or obese increases risk for cardiometabolic disorders. Although both body mass index (BMI) and waist circumference (WC) measure the level of overweight and obesity, WC may be more important because of its closer relationship to total body fat. Because WC is typically not assessed in clinical practice, this study sought to develop and verify a model to predict WC from BMI and demographic data, and to use the predicted WC to assess cardiometabolic risk. Data were obtained from the Third National Health and Nutrition Examination Survey (NHANES) and the Atherosclerosis Risk in Communities Study (ARIC). We developed linear regression models for men and women using NHANES data, fitting waist circumference as a function of BMI. For validation, those regressions were applied to ARIC data, assigning a predicted WC to each individual. We used the predicted WC to assess abdominal obesity and cardiometabolic risk. The model correctly classified 88.4% of NHANES subjects with respect to abdominal obesity. Median differences between actual and predicted WC were -0.07 cm for men and 0.11 cm for women. In ARIC, the model closely estimated the observed WC (median difference: -0.34 cm for men, +3.94 cm for women), correctly classifying 86.1% of ARIC subjects with respect to abdominal obesity and 91.5% to 99.5% as to cardiometabolic risk.The model is generalizable to Caucasian and African-American adult populations because it was constructed from data on a large, population-based sample of men and women in the United States, and then validated in a population with a larger representation of African-Americans. The model accurately estimates WC and identifies cardiometabolic risk. It should be useful for health care practitioners and public health officials who wish to identify individuals and populations at risk for cardiometabolic disease when WC data are unavailable.

Changes in Adult BMI and Waist Circumference Are Associated with Increased Risk of Advanced Colorectal Neoplasia.

Science.gov (United States)

Gathirua-Mwangi, Wambui G; Monahan, Patrick; Song, Yiqing; Zollinger, Terrell W; Champion, Victoria L; Stump, Timothy E; Imperiale, Thomas F

2017-11-01

Waist circumference (WC) is a stronger predictor of colon cancer (CRC) risk than body mass index (BMI). However, how well change in either WC or BMI predicts risk of advanced colorectal neoplasia (AN) is unclear. To determine the relationship between change in BMI and WC from early adulthood to later age and the risk of AN and which change measure is a stronger predictor. In 4500 adults, ages 50-80, with no previous neoplasia and undergoing screening colonoscopy, BMI and WC at age 21 and at time of screening were reported. Changes in BMI and WC were defined using universal risk cutoffs. Known CRC risk factors were controlled in the logistic models. Overall, model statistics showed WC change (omnibus test χ 2  = 10.15, 2 DF, p value = 0.006) was a statistically stronger predictor of AN than BMI change (omnibus test χ 2  = 5.66, 5 DF, p value = 0.34). Independent of BMI change, participants who increased WC (OR 1.44; 95% CI 1.05-1.96) or maintained a high-risk WC (OR 2.50; 95% CI 1.38-4.53) at age 21 and at screening had an increased risk of AN compared to those with a low-risk WC. Study participants who were obese at age 21 and at screening had an increased risk of AN (OR 1.87; 95% CI 1.08-3.23) compared to those who maintained a healthy BMI. Maintaining an overweight BMI or increasing BMI was not associated with AN. Maintaining an unhealthy BMI and WC throughout adult life may increase risk of AN. WC change may be a better predictor of AN than BMI change.

Is the 90th Percentile Adequate? The Optimal Waist Circumference Cutoff Points for Predicting Cardiovascular Risks in 124,643 15-Year-Old Taiwanese Adolescents.

Directory of Open Access Journals (Sweden)

Jason Jiunshiou Lee

Full Text Available Adolescent obesity has increased to alarming proportions globally. However, few studies have investigated the optimal waist circumference (WC of Asian adolescents. This study sought to establish the optimal WC cutoff points that identify a cluster of cardiovascular risk factors (CVRFs among 15-year-old ethnically Chinese adolescents. This study was a regional population-based study on the CVRFs among adolescents who enrolled in all the senior high schools in Taipei City, Taiwan, between 2011 and 2014. Four cross-sectional health examinations of first-year senior high school (grade 10 students were conducted from September to December of each year. A total of 124,643 adolescents aged 15 (boys: 63,654; girls: 60,989 were recruited. Participants who had at least three of five CVRFs were classified as the high-risk group. We used receiver-operating characteristic curves and the area under the curve (AUC to determine the optimal WC cutoff points and the accuracy of WC in predicting high cardiovascular risk. WC was a good predictor for high cardiovascular risk for both boys (AUC: 0.845, 95% confidence interval [CI]: 0.833-0.857 and girls (AUC: 0.763, 95% CI: 0.731-0.795. The optimal WC cutoff points were ≥78.9 cm for boys (77th percentile and ≥70.7 cm for girls (77th percentile. Adolescents with normal weight and an abnormal WC were more likely to be in the high cardiovascular risk group (odds ratio: 3.70, 95% CI: 2.65-5.17 compared to their peers with normal weight and normal WC. The optimal WC cutoff point of 15-year-old Taiwanese adolescents for identifying CVRFs should be the 77th percentile; the 90th percentile of the WC might be inadequate. The high WC criteria can help health professionals identify higher proportion of the adolescents with cardiovascular risks and refer them for further evaluations and interventions. Adolescents' height, weight and WC should be measured as a standard practice in routine health checkups.

Definition of new cut-offs of BMI and waist circumference based on body composition and insulin resistance: differences between children, adolescents and adults.

Science.gov (United States)

Hübers, M; Pourhassan, M; Braun, W; Geisler, C; Müller, M J

2017-09-01

This study aims to determine associations between anthropometric traits, regional fat depots and insulin resistance in children, adolescents and adults to define new cut-offs of body mass index (BMI) or waist circumference (WC). Cross-sectional data were assessed in 433 children, adolescents and adults (aged: 6-60 years, BMI: 23.6 [21.0-27.7] kg m -2 ). Total adipose tissue (TAT), regional subcutaneous adipose tissue (SAT total , SAT trunk ) and visceral adipose tissue (VAT) were determined by whole-body magnetic resonance imaging, fat mass by air-displacement plethysmography. Insulin resistance was evaluated by homeostasis model assessment of insulin resistance (HOMA-IR). Bivariate as well as partial correlations and regression analyses were used. Cut-off values of BMI and WC related to regional fat depots and HOMA-IR were analysed by receiver operating characteristics curve. In adults, TAT, SAT total and SAT trunk increased linearly with increasing BMI and WC, whereas they followed a cubic function in children and adolescents with a steep increase at BMI and WC ≥1 standard deviation score and VAT at WC ≥2 standard deviation score. Sex differences were apparent in adults with women having higher masses of TAT and SAT and men having higher VAT. Using established BMI or WC cut-offs, correspondent masses of TAT, SAT total , SAT trunk and VAT increased from childhood to adulthood. In all age groups, there were positive associations between BMI, WC, SAT trunk , VAT and HOMA-IR. When compared with normative cut-offs of BMI or WC, HOMA-IR-derived cut-offs of regional fat depots were lower in all age groups. Associations between BMI, WC and regional fat depots varied between children, adolescents, young and older adults. When compared with BMI-derived and WC-derived values, an insulin resistance-derived cut-off corresponded to lower masses of regional fat depots. Thus, established BMI and WC cut-offs are not appropriate to assess metabolic disturbances associated

Optimal central obesity measurement site for assessing cardiometabolic and type 2 diabetes risk in middle-aged adults.

Directory of Open Access Journals (Sweden)

Seán R Millar

Full Text Available Despite recommendations that central obesity assessment should be employed as a marker of cardiometabolic health, no consensus exists regarding measurement protocol. This study examined a range of anthropometric variables and their relationships with cardiometabolic features and type 2 diabetes in order to ascertain whether measurement site influences discriminatory accuracy. In particular, we compared waist circumference (WC measured at two sites: (1 immediately below the lowest rib (WC rib and (2 between the lowest rib and iliac crest (WC midway, which has been recommended by the World Health Organisation and International Diabetes Federation.This was a cross-sectional study involving a random sample of 2,002 men and women aged 46-73 years. Metabolic profiles and WC, hip circumference, pelvic width and body mass index (BMI were determined. Correlation, logistic regression and area under the receiver operating characteristic curve analyses were used to evaluate obesity measurement relationships with metabolic risk phenotypes and type 2 diabetes.WC rib measures displayed the strongest associations with non-optimal lipid and lipoprotein levels, high blood pressure, insulin resistance, impaired fasting glucose, a clustering of metabolic risk features and type 2 diabetes, in both genders. Rib-derived indices improved discrimination of type 2 diabetes by 3-7% compared to BMI and 2-6% compared to WC midway (in men and 5-7% compared to BMI and 4-6% compared to WC midway (in women. A prediction model including BMI and central obesity displayed a significantly higher area under the curve for WC rib (0.78, P=0.003, Rib/height ratio (0.80, P<0.001, Rib/pelvis ratio (0.79, P<0.001, but not for WC midway (0.75, P=0.127, when compared to one with BMI alone (0.74.WC rib is easier to assess and our data suggest that it is a better method for determining obesity-related cardiometabolic risk than WC midway. The clinical utility of rib-derived indices, or

Apoptosis induction in human lymphocytes after in vitro exposure to cobalt/hard metal compounds

International Nuclear Information System (INIS)

Boeck, M. de; Decordier, I.; Lombaert, N.; Cundari, E.; Kirsch-Volders, M.; Lison, D.

2001-01-01

Full text: An increased risk of lung cancer is associated with occupational exposure to mixtures of cobalt metal (Co) and tungsten carbide (WC) particles, but apparently not when exposure is to cobalt alone. The mechanism for this increased cancer risk is not fully understood. The evaluation of the in vitro genotoxic effects in lymphocytes exposed to varying cobalt species demonstrated that the WC-Co hard metal mixture is more genotoxic (DNA damage, chromosome/genome mutations) than metallic Co alone. WC alone was not genotoxic. Thus, WC-Co represents a specific (geno)toxic entity. In order to assess the survival of human lymphocytes after in vitro exposure to metallic Co, CoCl 2 , WC and the WC-Co mixture, two apoptosis/necrosis detection methods were applied (annexin V staining and flow cytometry). Annexin-V staining of early apoptotic cells demonstrated a dose- and time dependent induction of apoptosis by metallic Co, CoCl 2 , WC and the WC-Co mixture. The time course of the process varied according to the metal species tested. Metallic Co and CoCl 2 caused a gradually increasing frequency of apoptotic cells with time (up to 24 h). WC-induced apoptosis displayed a typical 6 hour peak, which was not the case for the WC-Co mixture or for Co. Apoptosis induction by the WC-Co mixture was intermediate between that induced by Co and WC separately. Analysis of propidium iodide stained cells by flow cytometry was performed as a later marker for apoptosis induction. Preliminary data indicate similar tendencies of apoptosis induction as those detected by annexin-V. Identification of the apoptotic pathway triggered by the metal compounds was studied by inhibition of the ceramide-apoptosis pathway by fumonisin causing reduction of apoptosis induction for all compounds, but strongest after 6 hour exposure to WC. The use of specific caspase inhibitors will allow to further elucidate the different pathways involved. The current data demonstrating in vitro the apoptosis

Apoptosis induction in human lymphocytes after in vitro exposure to cobalt/hard metal compounds

Energy Technology Data Exchange (ETDEWEB)

Boeck, M de; Decordier, I; Lombaert, N; Cundari, E; Kirsch-Volders, M [Vrije Universiteit Brussel, Laboratorium voor Cellulaire Genetica, Brussel (Belgium); Lison, D [Universite catholique de Louvain, Unite de Toxicologie industrielle et Medecine du Travail, Bruxelles (Belgium)

2001-07-01

Full text: An increased risk of lung cancer is associated with occupational exposure to mixtures of cobalt metal (Co) and tungsten carbide (WC) particles, but apparently not when exposure is to cobalt alone. The mechanism for this increased cancer risk is not fully understood. The evaluation of the in vitro genotoxic effects in lymphocytes exposed to varying cobalt species demonstrated that the WC-Co hard metal mixture is more genotoxic (DNA damage, chromosome/genome mutations) than metallic Co alone. WC alone was not genotoxic. Thus, WC-Co represents a specific (geno)toxic entity. In order to assess the survival of human lymphocytes after in vitro exposure to metallic Co, CoCl{sub 2}, WC and the WC-Co mixture, two apoptosis/necrosis detection methods were applied (annexin V staining and flow cytometry). Annexin-V staining of early apoptotic cells demonstrated a dose- and time dependent induction of apoptosis by metallic Co, CoCl{sub 2}, WC and the WC-Co mixture. The time course of the process varied according to the metal species tested. Metallic Co and CoCl{sub 2} caused a gradually increasing frequency of apoptotic cells with time (up to 24 h). WC-induced apoptosis displayed a typical 6 hour peak, which was not the case for the WC-Co mixture or for Co. Apoptosis induction by the WC-Co mixture was intermediate between that induced by Co and WC separately. Analysis of propidium iodide stained cells by flow cytometry was performed as a later marker for apoptosis induction. Preliminary data indicate similar tendencies of apoptosis induction as those detected by annexin-V. Identification of the apoptotic pathway triggered by the metal compounds was studied by inhibition of the ceramide-apoptosis pathway by fumonisin causing reduction of apoptosis induction for all compounds, but strongest after 6 hour exposure to WC. The use of specific caspase inhibitors will allow to further elucidate the different pathways involved. The current data demonstrating in vitro the

Waist circumference and waist-to-height ratio distributions in polish and german schoolchildren: Comparative analysis

Directory of Open Access Journals (Sweden)

Tadeusz Nawarycz

2013-01-01

Full Text Available Background: To analyze differences in the distributions of waist circumference (WC and waist-to-height ratio (WHtR between Polish (PL and German (GE children and adolescents. Methods: Two samples of children and adolescents aged 7-18 y: From PL ( n = 11,326 GE ( n = 8,218 participated. The two WC cut-off points (WC1 as central fat distribution and WC2 as central obesity corresponding at age 18 to the adult criteria were determined. Furthermore, the mean WC cut-off points (WC1m, WC2m for boys and girls aged 14-18 from both countries were evaluated. For the WHtR, values over 0.5 were used as a definition of central fat distribution. The effect of different WC and WHtR criteria on the prevalence of abdominal obesity in both study groups was evaluated. Results: The mean and percentile values of WC and WHtR were generally higher in all German children as compared to their peers from Poland. When WC1m is used, the mean (95% CI prevalence of central fat distribution in the 14-18 y Polish groups was lower ( P 0.5, the results were similar for boys - 6.7% (5.9-7.5 vs. 8.5% (8.1-8.9; they were significantly ( P < 0.05 lower for Polish and German girls: 5.3% (5.0-5.6 vs. 12.7% (9.7-16.4. The prevalence of central obesity using WC2m as a criterion in the Polish vs. German groups was as follows: (boys - 1.1% (0.8-1.4 vs. 3.1% (2.2-4.0, P < 0.05; girls - 3.1% (2.5-3.7 vs. 10.2% (8.4-12.0, P < 0.05. Conclusions: The results highlight the greater central obesity associated with the German children, both in terms of WC and WHtR, in comparison to their peers from Poland. The prevalence of AO is significantly associated with the criteria used. The results demonstrate the need for the development of international WC references for pediatric subjects.

ON THE EXPANSION RATE, AGE, AND DISTANCE OF THE SUPERNOVA REMNANT G266.2–1.2 (Vela Jr.)

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Allen, G. E. [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, NE83-557, Cambridge, MA 02139 (United States); Chow, K. [Weston High School, 444 Wellesley Street, Weston, MA 02493 (United States); DeLaney, T. [Department of Physics and Engineering, West Virginia Wesleyan College, Box 112, 59 College Avenue, Buckhannon, WV 26201 (United States); Filipović, M. D. [University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW 1797 (Australia); Houck, J. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Pannuti, T. G. [Space Science Center, Department of Earth and Space Sciences, Morehead State University, 235 Martindale Drive, Morehead, KY 40351 (United States); Stage, M. D., E-mail: gea@space.mit.edu, E-mail: kc71135@gmail.com, E-mail: delaney_t@wvwc.edu, E-mail: m.filipovic@uws.edu.au, E-mail: jhouck@cfa.harvard.edu, E-mail: t.pannuti@moreheadstate.edu, E-mail: mikstage@astro.umass.edu [Department of Astronomy, University of Massachusetts, LGRT-B 619E, 710 North Pleasant Street, Amherst, MA 01003-9305 (United States)

2015-01-10

An analysis of Chandra ACIS data for two relatively bright and narrow portions of the northwestern rim of G266.2–1.2 (a.k.a. RX J0852.0-4622 or Vela Jr.) reveal evidence of a radial displacement of 2.40 ± 0.56 arcsec between 2003 and 2008. The corresponding expansion rate (0.42 ± 0.10 arcsec yr{sup –1} or 13.6% ± 4.2% kyr{sup –1}) is about half the rate reported for an analysis of XMM-Newton data from a similar, but not identical, portion of the rim over a similar, but not identical, time interval (0.84 ± 0.23 arcsec yr{sup –1}). If the Chandra rate is representative of the remnant as a whole, then the results of a hydrodynamic analysis suggest that G266.2–1.2 is between 2.4 and 5.1 kyr old if it is expanding into a uniform ambient medium (whether or not it was produced by a Type Ia or Type II event). If the remnant is expanding into the material shed by a steady stellar wind, then the age could be as much as 50% higher. The Chandra expansion rate and a requirement that the shock speed be greater than or equal to 1000 km s{sup –1} yields a lower limit on the distance of 0.5 kpc. An analysis of previously published distance estimates and constraints suggests G266.2–1.2 is no further than 1.0 kpc. This range of distances is consistent with the distance to the nearer of two groups of material in the Vela Molecular Ridge (0.7 ± 0.2 kpc) and to the Vel OB1 association (0.8 kpc)

Atherosclerosis risk factors in pigeon squabs

International Nuclear Information System (INIS)

Klumpp, S.A.; Clarkson, T.B.

1986-01-01

The basis for atherosclerosis susceptibility of White Carneau (WC) and resistance of Show Racer (SR) pigeons is not known. Body weight (BW), total serum cholesterol (TSC), growth of the aorta and replication of endothelial cells of the distal thoracic aorta (lesion prone site) of 1, 2 and 4 week old squabs were studied. Aortic measurements were determined morphometrically, and endothelial cell replication was quantitated by 24-hour 3 H-thymidine labeling and whole-mount SEM autoradiography. From hatching to 4 weeks, BW increased more in WC than SR (22 to 473 gm in WC vs 19 to 416 gm in SR, p 2 ) in WC and 44% (101, 140 and 146 mm 2 ) in SR. Aortic surface area was significantly larger (0 = 0.002) in the 4 week WC than 4 week SR. 3 H-thymidine labeled endothelial cells at 1, 2 and 4 weeks were 783, 387 and 53 in WC and 674, 283 and 27 cells/mm 2 in SR. Endothelial replication in the 4 week WC was twice that of the SR and significantly different between breeds at 2 and 4 weeks (p = 0.04; p = 0.02, respectively). Higher TSC, endothelial cell replication and larger aortic surface area in the WC may be contributing factors to increased atherosclerosis susceptibility

Hydrogen chemisorption and oxidation of transition metal carbides

International Nuclear Information System (INIS)

Bethin, J.R.

1979-01-01

A study was made of the catalytic activity of WC, focusing on the possible influence of point defects. The chemisorption of H on WC and titanium oxycarbides was studied with differential scanning calorimetry. The catalytic activity of these materials for oxidation of H was determined by potentiostatic steady-state and potentiodynamic measurements in acid electrolyte. Compositions of WC surfaces were determined by x-ray photoemission and related to the catalytic behavior. Titanium oxycarbide surfaces were analyzed by Auger electron spectroscopy. Of the carbides tested only one WC preparation was able to chemisorb H. Both WC powders investigated catalyzed H oxidation with similar specific activities. Spectroscopic studies showed that the active surface of WC was a mixture of WO 3 and a carbon-deficient WC phase. This result indicates that carbon vacancies are the active sites in tungsten carbide. Theoretical models of a carbon vacancy surrounded by metal atoms suggested by calculations by other workers support this assignment and identify the important role of the W6s level. The measured value of the heat of chemisorption is consistent with the proposed model

Waist circumference adjusted for body mass index and intra-abdominal fat mass

DEFF Research Database (Denmark)

Berentzen, Tina Landsvig; Ängquist, Lars; Kotronen, Anna

2012-01-01

The association between waist circumference (WC) and mortality is particularly strong and direct when adjusted for body mass index (BMI). One conceivable explanation for this association is that WC adjusted for BMI is a better predictor of the presumably most harmful intra-abdominal fat mass (IAFM......) than WC alone. We studied the prediction of abdominal subcutaneous fat mass (ASFM) and IAFM by WC alone and by addition of BMI as an explanatory factor....

Impact of communication strategies to increase knowledge, acceptability, and uptake of a new Woman's Condom in urban Lusaka, Zambia: study protocol for a randomized controlled trial.

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Pinchoff, Jessie; Chowdhuri, Rachna Nag; Taruberekera, Noah; Ngo, Thoai D

2016-12-13

Globally, 220 million women experience an unmet need for family planning. A newly designed female condom, the Woman's Condom (WC), has been developed featuring an improved design. It is the first dual-protection, female-initiated contraceptive that is a premium, higher price point product. However, market availability alone will not increase uptake. In February 2016 the WC will be distributed with a strong media campaign and interpersonal communication (IPC) outreach intervention. The impact of these on knowledge, acceptability, and use of the WC will be measured. A baseline survey of 2314 randomly selected 18- to 24-year-old sexually active men and women has been conducted. The WC and mass media will be introduced throughout 40 urban wards in and surrounding Lusaka, Zambia. The baseline survey will serve as a quasi-control arm to determine the impact of introducing the WC with mass media. Half of the wards will be randomly allocated to additionally receive the IPC intervention. A single-blind randomized controlled trial will determine the impact of the IPC intervention on knowledge, uptake, and use of the WC. After one year, another 2314 individuals will be randomly selected to participate in the endline survey. We hypothesize that (1) the distribution and media campaign of the WC will increase overall condom use in selected urban wards, and specifically use of the WC; (2) the IPC intervention will significantly impact knowledge, acceptability, and use of the WC. The primary outcome measures are use of the WC, use of any condom, and willingness to use the WC. Secondary outcomes include measures of knowledge, acceptability, and choice of contraception. Odds ratios will be estimated to measure the effect of the intervention on the outcomes with 95% confidence intervals. All analyses will be based on the intention-to-treat principle. Increasing uptake of dual prevention measures (such as the WC) may reduce incidence of sexually transmitted infections/HIV and

The cutoff values of visceral fat area and waist circumference for identifying subjects at risk for metabolic syndrome in elderly Korean: Ansan Geriatric (AGE cohort study

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Koh Young

2009-12-01

Full Text Available Abstract Background In Korea, the cutoff values of waist circumference (WC for the identification of metabolic syndrome (MetS were suggested to be 90 cm for men and 85 cm for women based on the analysis mainly in middle-aged adults. As aging is associated with increased fat, especially abdominal visceral fat, the cutoff value of WC may differ according to age. In addition, the usefulness of visceral abdominal fat area (VFA to predict MetS in the elderly has not been studied yet. We aimed to suggest WC and VFA criteria and to compare the predictability of WC and VFA to identify people at risk for MetS. Methods A total of 689 elderly subjects aged ≥63 years (308 men, 381 women were chosen in this cross-sectional study from an ongoing, prospective, population-based study, the Ansan Geriatric (AGE cohort study. VFA was measured by single slice abdominal computed tomography scanning. The metabolic risk factors except WC (plasma glucose, blood pressure, serum triglycerides and HDL cholesterol levels were defined using modified NCEP-ATP III criteria. We estimated the accuracy of VFA and WC for identifying at least two of these factors by receiver operating characteristic (ROC curve analysis. Results Two hundred three of 308 men and 280 of 381 women had ≥2 metabolic risk factors. The area under the ROC curve (AUC value for VFA to predict the presence of ≥2 metabolic risk factors was not significantly different from that for WC (men, 0.735 and 0.750; women, 0.715 and 0.682; AUC values for VFA and WC, respectively. The optimal cutoff points for VFA and WC for predicting the presence of ≥2 metabolic risk factors were 92.6 cm2 and 86.5 cm for men and 88.9 cm2 and 86.5 cm for women. Conclusion WC had comparable power with VFA to identify elderly people who are at risk for MetS. Elderly Korean men and women had very similar cutoff points for both VFA and WC measurements for estimating the risk of MetS. Age-specific cutoff point for WC might be

pH-dependence of pesticide adsorption by wheat-residue-derived black carbon.

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Yang, Yaning; Chun, Yuan; Sheng, Guangyao; Huang, Minsheng

2004-08-03

The potential of black carbon as an adsorbent for pesticides in soils may be strongly influenced by the properties of the adsorbent and pesticides and by the environmental conditions. This study evaluated the effect of pH on the adsorption of diuron, bromoxynil, and ametryne by a wheat (Triticum aestivum L.) residue derived black carbon (WC) as compared to a commercial activated carbon (AC). The pH drift method indicated that WC had a point of zero charge of 4.2, much lower than that of 7.8 for AC. The density of oxygen-containing surface functional groups, measured by the Boehm titration, on WC was 5.4 times higher than that on AC, resulting in a pesticide adsorption by WC being 30-50% of that by AC, due to the blockage of WC surface by the waters associated with the functional groups. A small decrease (5.5%/unit pH) in diuron adsorption by WC with increase in pH resulted from increased deprotonation of surface functional groups at higher pH values. A much larger decrease (14-21%/unit pH) in bromoxynil adsorption by WC with increase in pH resulted from the deprotonation of both the adsorbate and surface functional groups of the adsorbent. The deprotonation reduced the adsorptive interaction between bromoxynil and the neutral carbon surface and increased the electrical repulsion between the negatively charged WC surface and bromoxynil anions. Deprotonation of ametryne with increase in pH over the low pH range increased its fraction of molecular form and thus adsorption on WC by 15%/unit pH. Further increase in pH resulted in a 20%/unit pH decrease in ametryne adsorption by WC due primarily to the development of a negative charge on the surface of WC. The pH-dependent adsorption of pesticides by black carbon may significantly influence their environmental fate in soils.

Predicting waist circumference from body mass index

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Bozeman Samuel R

2012-08-01

Full Text Available Abstract Background Being overweight or obese increases risk for cardiometabolic disorders. Although both body mass index (BMI and waist circumference (WC measure the level of overweight and obesity, WC may be more important because of its closer relationship to total body fat. Because WC is typically not assessed in clinical practice, this study sought to develop and verify a model to predict WC from BMI and demographic data, and to use the predicted WC to assess cardiometabolic risk. Methods Data were obtained from the Third National Health and Nutrition Examination Survey (NHANES and the Atherosclerosis Risk in Communities Study (ARIC. We developed linear regression models for men and women using NHANES data, fitting waist circumference as a function of BMI. For validation, those regressions were applied to ARIC data, assigning a predicted WC to each individual. We used the predicted WC to assess abdominal obesity and cardiometabolic risk. Results The model correctly classified 88.4% of NHANES subjects with respect to abdominal obesity. Median differences between actual and predicted WC were − 0.07 cm for men and 0.11 cm for women. In ARIC, the model closely estimated the observed WC (median difference: − 0.34 cm for men, +3.94 cm for women, correctly classifying 86.1% of ARIC subjects with respect to abdominal obesity and 91.5% to 99.5% as to cardiometabolic risk. The model is generalizable to Caucasian and African-American adult populations because it was constructed from data on a large, population-based sample of men and women in the United States, and then validated in a population with a larger representation of African-Americans. Conclusions The model accurately estimates WC and identifies cardiometabolic risk. It should be useful for health care practitioners and public health officials who wish to identify individuals and populations at risk for cardiometabolic disease when WC data are unavailable.

Increase in waist circumference over 6 years predicts subsequent cardiovascular disease and total mortality in nordic women

DEFF Research Database (Denmark)

Klingberg, Sofia; Mehlig, Kirsten; Lanfer, Anne

2015-01-01

-shaped association. Associations between increase in WC and outcomes were restricted to women with normal weight at baseline and to ever-smokers. CONCLUSIONS: In contrast to changes in HC which did not predict mortality and CVD, a 6-year increase in WC is strongly predictive, particularly among initially lean women...... and cardiovascular disease (CVD) mortality in women but that gain or loss in HC was unrelated to these outcomes. This study examines whether a 6-year change in waist circumference (WC) predicts mortality and CVD in the same study sample. METHODS: Baseline WC and 6-year change in WC as predictors of mortality and CVD...... were analyzed in 2,492 women from the Danish MONICA study and the Prospective Population Study of Women in Gothenburg, Sweden. RESULTS: Increase in WC was significantly associated with increased subsequent mortality and CVD adjusting for BMI and other covariates, with some evidence of a J...

"Best Case/Worst Case": Training Surgeons to Use a Novel Communication Tool for High-Risk Acute Surgical Problems.

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Kruser, Jacqueline M; Taylor, Lauren J; Campbell, Toby C; Zelenski, Amy; Johnson, Sara K; Nabozny, Michael J; Steffens, Nicole M; Tucholka, Jennifer L; Kwekkeboom, Kris L; Schwarze, Margaret L

2017-04-01

Older adults often have surgery in the months preceding death, which can initiate postoperative treatments inconsistent with end-of-life values. "Best Case/Worst Case" (BC/WC) is a communication tool designed to promote goal-concordant care during discussions about high-risk surgery. The objective of this study was to evaluate a structured training program designed to teach surgeons how to use BC/WC. Twenty-five surgeons from one tertiary care hospital completed a two-hour training session followed by individual coaching. We audio-recorded surgeons using BC/WC with standardized patients and 20 hospitalized patients. Hospitalized patients and their families participated in an open-ended interview 30 to 120 days after enrollment. We used a checklist of 11 BC/WC elements to measure tool fidelity and surgeons completed the Practitioner Opinion Survey to measure acceptability of the tool. We used qualitative analysis to evaluate variability in tool content and to characterize patient and family perceptions of the tool. Surgeons completed a median of 10 of 11 BC/WC elements with both standardized and hospitalized patients (range 5-11). We found moderate variability in presentation of treatment options and description of outcomes. Three months after training, 79% of surgeons reported BC/WC is better than their usual approach and 71% endorsed active use of BC/WC in clinical practice. Patients and families found that BC/WC established expectations, provided clarity, and facilitated deliberation. Surgeons can learn to use BC/WC with older patients considering acute high-risk surgical interventions. Surgeons, patients, and family members endorse BC/WC as a strategy to support complex decision making. Copyright © 2017 American Academy of Hospice and Palliative Medicine. Published by Elsevier Inc. All rights reserved.

Triglyceride glucose-waist circumference, a novel and effective predictor of diabetes in first-degree relatives of type 2 diabetes patients: cross-sectional and prospective cohort study.

Science.gov (United States)

Zheng, Shuang; Shi, Sheng; Ren, Xingxing; Han, Tingting; Li, Yangxue; Chen, Yawen; Liu, Wei; Hou, Peter C; Hu, Yaomin

2016-09-07

Body mass index (BMI), waist circumference (WC), visceral adiposity index (VAI), triglyceride glucose index (TyG), TyG-BMI, and TyG-WC have been reported as markers of insulin resistance or type 2 diabetes mellitus (T2DM). However, little is known about the associations between the aforementioned markers and the risk of prediabetes and diabetes in first-degree relatives (FDRs) of T2DM patients. 1544 FDRs of T2DM patients (635 men and 909 women) were enrolled in the initial cross-sectional study and all of them finished corresponding examinations. Logistic regression analysis and receiver operating characteristic (ROC) curve were used to compare and identify the associations of the six parameters (BMI, WC, VAI, TyG, TyG-BMI and TyG-WC) with the prevalence of prediabetes and diabetes. Subsequently, 452 of them were followed-up for an average of 5 years. Cox proportional hazard regression model was applied to confirm the predictive value of the optimal marker. Among the indices, TyG-WC was more strongly associated with the prevalence of prediabetes and diabetes. Compared with participants in the lowest quartile of TyG-WC, the adjusted odds ratio and 95 % CIs for prediabetes and diabetes was 11.19 (7.62-16.42) for those in the top quartile of TyG-WC. Moreover, the largest AUC was also observed in TyG-WC (0.765, 95 % CIs 0.741-0.789, P < 0.001). The robust predictive value of TyG-WC was further confirmed in the follow-up study (HR: 7.13, 95 % CIs 3.41-14.90, P < 0.001). TyG-WC is a novel and clinically effective marker for early identifying the risks of prediabetes and diabetes in FDRs of T2DM patients.

Hollow hemisphere-shaped macroporous graphene/tungsten carbide/platinum nanocomposite as an efficient electrocatalyst for the oxygen reduction reaction

International Nuclear Information System (INIS)

Li, Zesheng; Liu, Zhisen; Li, Bolin; Liu, Zhenghui; Li, Dehao; Wang, Hongqiang; Li, Qingyu

2016-01-01

Graphical abstract: Newfashioned hollow hemisphere-shaped macroporous graphene/tungsten carbide/platinum (HMG/WC/Pt) nanocomposite with interesting three-dimensional architecture bas been successfully fabricated as an efficient electrocatalyst for the oxygen reduction reaction. - Highlights: • Hollow hemisphere-shaped macroporous graphene is proposed as ORR catalyst support. • Honeycomb-like macroporous graphene/WC/Pt electrocatalyst is firsy prepared for ORR. • The present electrocatalyst exhibited greatly enhanced ORR catalytic activity and stability. - Abstract: Hollow hemisphere-shaped macroporous graphene/tungsten carbide/platinum (HMG/WC/Pt) nanocomposite has been synthesized as an efficient electrocatalyst for the oxygen reduction reaction (ORR). The HMG/WC/Pt sample has been systematically characterized by the X-ray diffraction (XRD), Scanning electron microscope (SEM) and Transmission electron microscopy (TEM). The analysis results indicate that the sample has an interesting three-dimensional hollow hemisphere-shaped macroporous architecture. The results also demonstrate the successful integration of WC and Pt nanoparticles on the HMG, in which the WC nanoparticles are in size of about 10 nm and the Pt nanoparticles are in size of about 3 nm. The as-prepared HMG/WC/Pt electrode displays excellent electrocatalytic performances for the ORR in 0.1 mol L −1 HClO 4 electrolyte. The mass activity (i m at 0.9 V) of HMG/WC/Pt is 206 mA mg −1 Pt, which is about 85% higher than that of Pt/C (112 mA mg −1 Pt). It also displayed a very high activity retention of 84.5% after 2000 cyclic voltammetry cycles for the HMG/WC/Pt, while that of the Pt/C is only 70.5%. The HMG/WC/Pt nanocomposite would be a promising electrocatalytic material for the ORR in Fuel cell applications.

Combined use of waist and hip circumference to identify abdominally obese HIV-infected patients at increased health risk.

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Trevor O'Neill

Full Text Available OBJECTIVES: To determine whether for a given waist circumference (WC, a larger hip circumference (HC was associated with a reduced risk of insulin resistance, type 2 diabetes (T2D, hypertension and cardiovascular disease (CVD in HIV-infected patients. A second objective was to determine whether, for a given WC, the addition of HC improved upon estimates of abdominal adiposity, in particular visceral adipose tissue (VAT, compared to those obtained by WC alone. METHODS: HIV-infected men (N = 1481 and women (N = 841 were recruited between 2005 and 2009. WC and HC were obtained using standard techniques and abdominal adiposity was measured using computed tomography. RESULTS: After control for WC and covariates, HC was negatively associated with risk of insulin resistance (p<0.05 and T2D [Men: OR = 0.91 (95% CI: 0.86-0.96; Women: OR = 0.91 (95% CI: 0.84-0.98]. For a given WC, HC was also negatively associated with a lower risk of hypertension (p<0.05 and CVD [OR = 0.94 (95% CI: 0.88-0.99] in men, but not women. Although HC was negatively associated with VAT in men and women after control for WC (p<0.05, the addition of HC did not substantially improve upon the prediction of VAT compared to WC alone. CONCLUSIONS: The identification of HIV-infected individuals at increased health risk by WC alone is substantially improved by the addition of HC. Estimates of visceral adipose tissue by WC are not substantially improved by the addition of HC and thus variation in visceral adiposity may not be the conduit by which HC identifies increased health risk.

Correlation between Body Mass Index and Central Adiposity with Pregnancy Complications in Pregnant Women

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Mehrangiz Ebrahimi-Mameghani

2013-06-01

Full Text Available Background: The prevalence of obesity is increasing throughout the world. Obesity assessed by body mass index (BMI has shown to be associated with gestational complications while the relationship using waist circumference (WC is not clear yet. The present study was aimed to determine the relationship be-tween WC and adverse pregnancy complications.Methods: In this prospective cohort study, 1140 nulliparous pregnant women at 1st trimester of pregnancy referred to health care centers in Tabriz, Iran were enrolled in 2009-2010. Anthropometric indexes including (weight, height and WC were measured using standardized measures and methods. BMI was clas-sified into normal, overweight and obesity based on WHO classification. Ab-dominal obesity was defined as WC ≥ 88 cm. Pregnancy complication including gestational diabetes, hypertension and preeclamsia. Data were analyzed using SPSS, version 16.Results: Mean of BMI and WC were 24.32±4.08 kg/m2, 81.84±9.25cm at 1st trimester of pregnancy, respectively. Prevalence of overweight (BMI=25-29.9 kg/m2 and obesity (BMI>29.9 kg/m2 was 27.6%, 8.8%, respectively. Abdo-minal obesity based on WC was 34.8%. Significant correlations were found between BMI and WC (r=0.73, P =0.0001. Women with BMI>29.9 kg/m2 and WC>88 cm were more likely to suffer from gestational pregnancy and hyper-tension, as well as preeclampsia and preterm delivery.Conclusion: Early maternal WC similar to BMI is related with pregnancy complications.

Effect of surfactant concentration in the electrolyte on the tribological properties of nickel-tungsten carbide composite coatings produced by pulse electro co-deposition

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Kartal, Muhammet, E-mail: kartal@sakarya.edu.tr [Sakarya University, Engineering Faculty, Metallurgical & Materials Engineering Department, Esentepe Campus, 54187 Sakarya (Turkey); Uysal, Mehmet [Sakarya University, Engineering Faculty, Metallurgical & Materials Engineering Department, Esentepe Campus, 54187 Sakarya (Turkey); Gul, Harun [Duzce University, Gumusova Vocational School, 81850 Duzce (Turkey); Alp, Ahmet; Akbulut, Hatem [Sakarya University, Engineering Faculty, Metallurgical & Materials Engineering Department, Esentepe Campus, 54187 Sakarya (Turkey)

2015-11-01

Highlights: • Effect of surfactant concentration on the co-deposited WC was investigated. • In the Ni matrix significantly high hardness was achieved by WC co-deposition. • Optimum surfactant resulted in obtaining superior wear resistance in the Ni. • Friction coefficient was decreased by WC co-deposition in the Ni matrix. - Abstract: A nickel plating bath containing WC particles was used to obtain hard and wear-resistant particle reinforced Ni/WC MMCs on steel surfaces for anti-wear applications. Copper substrates were used for electro co-deposition of Ni matrix/WC with the particle size of <1 μm tungsten carbide reinforcements. The influence of surfactant (sodium dodecyl sulfate, SDS) concentration on particle distribution, microhardness and wear resistance of composite coatings has been studied. The nickel films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of the surfactant on the zeta potential, co-deposition and distribution of WC particles in the nickel matrix, as well as the tribological properties of composite coatings were also investigated. The tribological behaviors of the electrodeposited WC composite coatings sliding against M50 steel ball (Ø 10 mm) were examined on a CSM Instrument. All friction and wear tests were performed without lubrication at room temperature and in the ambient air (relative humidity 55–65%).

Changes in waist circumference and mortality in middle-aged men and women

DEFF Research Database (Denmark)

Berentzen, Tina Landsvig; Jakobsen, Marianne Uhre; Halkjaer, Jytte

2010-01-01

Waist circumference (WC) adjusted for body mass index (BMI) is positively associated with mortality, but the association with changes in WC is less clear. We investigated the association between changes in WC and mortality in middle-aged men and women, and evaluated the influence from concurrent...

BMI and waist circumference; cross-sectional and prospective associations with blood pressure and cholesterol in 12-year-olds.

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Marga B M Bekkers

Full Text Available OBJECTIVE: Childhood and adolescent overweight, defined by body mass index (BMI are associated with an increased risk of cardiovascular disease in later life. Abdominal adiposity may be more important in associations with cardiovascular diseases but waist circumference (WC has been rarely studied in children. We studied associations between BMI and WC and blood pressure (BP and cholesterol in 12-year-old children and prospectively changes in BMI or WC status between age 8 and 12 years and BP and cholesterol at age 12. STUDY DESIGN: Weight, height, WC, BP and cholesterol concentrations were measured in 1432 children at age 12 years. Linear regression was used to study the associations between high BMI and large WC (>90(th percentile and BP and cholesterol. RESULTS: Systolic BP was 4.9 mmHg higher (95% (CI 2.5, 7.2 in girls and 4.2 mmHg (95%CI 1.9, 6.5 in boys with a high BMI. Large WC was also associated with higher systolic BP in girls (3.7 mmHg (95%CI 1.3, 6.1 and boys (3.5 mmHg (95%CI 1.2, 5.8. Diastolic BP and cholesterol concentrations were significantly positively (HDL cholesterol negatively associated with high BMI and large WC, too. Normal weight children with a history of overweight did not have higher blood pressure levels or adverse cholesterol concentrations than children that were normal weight at both ages. CONCLUSION: A high BMI and large WC were associated with higher BP levels and adverse cholesterol concentrations. WC should be taken into account when examining cardiovascular risk factors in children.

Post-surgical infections and perioperative antibiotics usage in pediatric genitourinary procedures.

Science.gov (United States)

Ellett, Justin; Prasad, Michaella M; Purves, J Todd; Stec, Andrew A

2015-12-01

Post-surgical infections (PSIs) are a source of preventable perioperative morbidity. No guidelines exist for the use of perioperative antibiotics in pediatric urologic procedures. This study reports the rate of PSIs in non-endoscopic pediatric genitourinary procedures at our institution. Secondary aims evaluate the association of PSI with other perioperative variables, including wound class (WC) and perioperative antibiotic administration. Data from consecutive non-endoscopic pediatric urologic procedures performed between August 2011 and April 2014 were examined retrospectively. The primary outcome was the rate of PSIs. PSIs were classified as superficial skin (SS) and deep/organ site (D/OS) according to Centers for Disease Control and Prevention guidelines, and urinary tract infection (UTI). PSIs were further stratified by WC1 and WC2 and perioperative antibiotic usage. A relative risk and chi-square analysis compared PSI rates between WC1 and WC2 procedures. A total of 1185 unique patients with 1384 surgical sites were reviewed; 1192 surgical sites had follow-up for inclusion into the study. Ten total PSIs were identified, for an overall infection rate of 0.83%. Of these, six were SS, one was D/OS, and three were UTIs. The PSI rate for WC1 (885 sites) and WC2 (307 sites) procedures was 0.34% and 2.28%, respectively, p antibiotics (0.35% vs. 0.33%). All WC2 procedures received antibiotics. Post-surgical infections are associated with significant perioperative morbidity. In some studies, PSI can double hospital costs, and contribute to hospital length of stay, admission to intensive care units, and impact patient mortality. Our study demonstrates that the rate of PSI in WC1 operations is low, irrespective of whether the patient received perioperative antibiotics (0.35%) or no antibiotics (0.33%). WC2 operations were the larger source of morbidity with an infection rate of 2.28% and a 6.7 fold higher increase in relative risk. WC1 procedures have a rate of

Methanol electro-oxidation on platinum modified tungsten carbides in direct methanol fuel cells: a DFT study.

Science.gov (United States)

Sheng, Tian; Lin, Xiao; Chen, Zhao-Yang; Hu, P; Sun, Shi-Gang; Chu, You-Qun; Ma, Chun-An; Lin, Wen-Feng

2015-10-14

In exploration of low-cost electrocatalysts for direct methanol fuel cells (DMFCs), Pt modified tungsten carbide (WC) materials are found to be great potential candidates for decreasing Pt usage whilst exhibiting satisfactory reactivity. In this work, the mechanisms, onset potentials and activity for electrooxidation of methanol were studied on a series of Pt-modified WC catalysts where the bare W-terminated WC(0001) substrate was employed. In the surface energy calculations of a series of Pt-modified WC models, we found that the feasible structures are mono- and bi-layer Pt-modified WCs. The tri-layer Pt-modified WC model is not thermodynamically stable where the top layer Pt atoms tend to accumulate and form particles or clusters rather than being dispersed as a layer. We further calculated the mechanisms of methanol oxidation on the feasible models via methanol dehydrogenation to CO involving C-H and O-H bonds dissociating subsequently, and further CO oxidation with the C-O bond association. The onset potentials for the oxidation reactions over the Pt-modified WC catalysts were determined thermodynamically by water dissociation to surface OH* species. The activities of these Pt-modified WC catalysts were estimated from the calculated kinetic data. It has been found that the bi-layer Pt-modified WC catalysts may provide a good reactivity and an onset oxidation potential comparable to pure Pt and serve as promising electrocatalysts for DMFCs with a significant decrease in Pt usage.

Abdominal obesity and physical inactivity are associated with erectile dysfunction independent of body mass index.

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Janiszewski, Peter M; Janssen, Ian; Ross, Robert

2009-07-01

Erectile dysfunction (ED) is common among men with an elevated body mass index (BMI). However, a high waist circumference (WC) and low levels of physical activity may predict ED independently of BMI. We investigated the independent relationships between BMI, WC, and physical activity with ED. Subjects consisted of 3,941 adult men (age > or = 20 years) with no history of prostate cancer from the 2001-2004 National Health and Nutrition Examination Survey. Logistic regression analyses were used to examine the relative odds of ED association with categories of BMI, WC, and physical activity. Established thresholds were used to divide subjects into three WC and BMI categories. Physical activity level was divided into active (> or =150 min/week), moderately active (30-149 min/week), and inactive (inactive men had an approximately 40-60% greater odds of ED compared with active men. When all three predictors (WC, BMI, and physical activity level) were entered into the same logistic regression model, both a high WC and low physical activity level (moderately active and inactive) were independently associated with a greater odds of ED, whereas BMI level was not. Maintaining a WC level below 102 cm and achieving the recommended amount of moderate-intensity physical activity (>or =150 min/week) is associated with the maintenance of proper erectile function, regardless of BMI level. These findings suggest that the clinical screening for ED risk should include the assessment of WC and physical activity level in addition to BMI.

Dietary determinants of changes in waist circumference adjusted for body mass index - a proxy measure of visceral adiposity.

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Dora Romaguera

2010-07-01

Full Text Available Given the recognized health effects of visceral fat, the understanding of how diet can modulate changes in the phenotype "waist circumference for a given body mass index (WC(BMI", a proxy measure of visceral adiposity, is deemed necessary. Hence, the objective of the present study was to assess the association between dietary factors and prospective changes in visceral adiposity as measured by changes in the phenotype WC(BMI.We analyzed data from 48,631 men and women from 5 countries participating in the European Prospective Investigation into Cancer and Nutrition (EPIC study. Anthropometric measurements were obtained at baseline and after a median follow-up time of 5.5 years. WC(BMI was defined as the residuals of waist circumference regressed on body mass index, and annual change in WC(BMI (DeltaWC(BMI, cm/y was defined as the difference between residuals at follow-up and baseline, divided by follow-up time. The association between energy, energy density (ED, macronutrients, alcohol, glycemic index (GI, glycemic load (GL, fibre and DeltaWC(BMI was modelled using centre-specific adjusted linear regression, and random-effects meta-analyses to obtain pooled estimates. Men and women with higher ED and GI diets showed significant increases in their WC(BMI, compared to those with lower ED and GI [1 kcal/g greater ED predicted a DeltaWC(BMI of 0.09 cm (95% CI 0.05 to 0.13 in men and 0.15 cm (95% CI 0.09 to 0.21 in women; 10 units greater GI predicted a DeltaWC(BMI of 0.07 cm (95% CI 0.03 to 0.12 in men and 0.06 cm (95% CI 0.03 to 0.10 in women]. Among women, lower fibre intake, higher GL, and higher alcohol consumption also predicted a higher DeltaWC(BMI.Results of this study suggest that a diet with low GI and ED may prevent visceral adiposity, defined as the prospective changes in WC(BMI. Additional effects may be obtained among women of low alcohol, low GL, and high fibre intake.

Waist Circumferences of Chilean Students: Comparison of the CDC-2012 Standard and Proposed Percentile Curves

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Rossana Gómez-Campos

2015-07-01

Full Text Available The measurement of waist circumference (WC is considered to be an important means to control overweight and obesity in children and adolescents. The objectives of the study were to (a compare the WC measurements of Chilean students with the international CDC-2012 standard and other international standards, and (b propose a specific measurement value for the WC of Chilean students based on age and sex. A total of 3892 students (6 to 18 years old were assessed. Weight, height, body mass index (BMI, and WC were measured. WC was compared with the CDC-2012 international standard. Percentiles were constructed based on the LMS method. Chilean males had a greater WC during infancy. Subsequently, in late adolescence, males showed values lower than those of the international standards. Chilean females demonstrated values similar to the standards until the age of 12. Subsequently, females showed lower values. The 85th and 95th percentiles were adopted as cutoff points for evaluating overweight and obesity based on age and sex. The WC of Chilean students differs from the CDC-2012 curves. The regional norms proposed are a means to identify children and adolescents with a high risk of suffering from overweight and obesity disorders.

Waist Circumferences of Chilean Students: Comparison of the CDC-2012 Standard and Proposed Percentile Curves

Science.gov (United States)

Gómez-Campos, Rossana; Lee Andruske, Cinthya; Hespanhol, Jefferson; Sulla Torres, Jose; Arruda, Miguel; Luarte-Rocha, Cristian; Cossio-Bolaños, Marco Antonio

2015-01-01

The measurement of waist circumference (WC) is considered to be an important means to control overweight and obesity in children and adolescents. The objectives of the study were to (a) compare the WC measurements of Chilean students with the international CDC-2012 standard and other international standards, and (b) propose a specific measurement value for the WC of Chilean students based on age and sex. A total of 3892 students (6 to 18 years old) were assessed. Weight, height, body mass index (BMI), and WC were measured. WC was compared with the CDC-2012 international standard. Percentiles were constructed based on the LMS method. Chilean males had a greater WC during infancy. Subsequently, in late adolescence, males showed values lower than those of the international standards. Chilean females demonstrated values similar to the standards until the age of 12. Subsequently, females showed lower values. The 85th and 95th percentiles were adopted as cutoff points for evaluating overweight and obesity based on age and sex. The WC of Chilean students differs from the CDC-2012 curves. The regional norms proposed are a means to identify children and adolescents with a high risk of suffering from overweight and obesity disorders. PMID:26184250

Weight training, aerobic physical activities, and long-term waist circumference change in men.

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Mekary, Rania A; Grøntved, Anders; Despres, Jean-Pierre; De Moura, Leandro Pereira; Asgarzadeh, Morteza; Willett, Walter C; Rimm, Eric B; Giovannucci, Edward; Hu, Frank B

2015-02-01

Findings on weight training and waist circumference (WC) change are controversial. This study examined prospectively whether weight training, moderate to vigorous aerobic activity (MVAA), and replacement of one activity for another were associated with favorable changes in WC and body weight (BW). Physical activity, WC, and BW were reported in 1996 and 2008 in a cohort of 10,500 healthy U.S. men in the Health Professionals Follow-up Study. Multiple linear regression models (partition/substitution) to assess these associations were used. After adjusting for potential confounders, a significant inverse dose-response relationship between weight training and WC change (P-trend weight training (-0.67 cm, 95% CI -0.93, -0.41) than for MVAA (-0.33 cm, 95% CI -0.40, -0.27), other activities (-0.16 cm, 95% CI -0.28, -0.03), or TV watching (0.08 cm, 95% CI 0.05, 0.12). Substituting 20 min/day of weight training for any other discretionary activity had the strongest inverse association with WC change. MVAA had the strongest inverse association with BW change (-0.23 kg, 95% CI -0.29, -0.17). Among various activities, weight training had the strongest association with less WC increase. Studies on frequency/volume of weight training and WC change are warranted. © 2014 The Obesity Society.

Shock propagation in a cemented tungsten carbide

NARCIS (Netherlands)

Appleby-Thomas, G.J.; Hazell, P.J.; Stennett, C.; Cooper, G.; Herlaar, K.; Diederen, A.M.

2009-01-01

WC-based ceramic metal composites (cermets) are of great importance in both armor and munition design due to the combination of properties imparted by the presence of two different phases. WC-Co cermets are of interest in this area due to the hardness and strength imparted by the WC phase while the

Participant characteristics associated with greater reductions in waist circumference during a four-month, pedometer-based, workplace health program.

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Freak-Poli, Rosanne L A; Wolfe, Rory; Walls, Helen; Backholer, Kathryn; Peeters, Anna

2011-10-25

Workplace health programs have demonstrated improvements in a number of risk factors for chronic disease. However, there has been little investigation of participant characteristics that may be associated with change in risk factors during such programs. The aim of this paper is to identify participant characteristics associated with improved waist circumference (WC) following participation in a four-month, pedometer-based, physical activity, workplace health program. 762 adults employed in primarily sedentary occupations and voluntarily enrolled in a four-month workplace program aimed at increasing physical activity were recruited from ten Australian worksites in 2008. Seventy-nine percent returned at the end of the health program. Data included demographic, behavioural, anthropometric and biomedical measurements. WC change (before versus after) was assessed by multivariable linear and logistic regression analyses. Seven groupings of potential associated variables from baseline were sequentially added to build progressively larger regression models. Greater improvement in WC during the program was associated with having completed tertiary education, consuming two or less standard alcoholic beverages in one occasion in the twelve months prior to baseline, undertaking less baseline weekend sitting time and lower baseline total cholesterol. A greater WC at baseline was strongly associated with a greater improvement in WC. A sub-analysis in participants with a 'high-risk' baseline WC revealed that younger age, enrolling for reasons other than appearance, undertaking less weekend sitting time at baseline, eating two or more pieces of fruit per day at baseline, higher baseline physical functioning and lower baseline body mass index were associated with greater odds of moving to 'low risk' WC at the end of the program. While employees with 'high-risk' WC at baseline experienced the greatest improvements in WC, the other variables associated with greater WC improvement

Long-term risk of incident type 2 diabetes and measures of overall and regional obesity: the EPIC-InterAct case-cohort study.

Directory of Open Access Journals (Sweden)

Claudia Langenberg

Full Text Available Waist circumference (WC is a simple and reliable measure of fat distribution that may add to the prediction of type 2 diabetes (T2D, but previous studies have been too small to reliably quantify the relative and absolute risk of future diabetes by WC at different levels of body mass index (BMI.The prospective InterAct case-cohort study was conducted in 26 centres in eight European countries and consists of 12,403 incident T2D cases and a stratified subcohort of 16,154 individuals from a total cohort of 340,234 participants with 3.99 million person-years of follow-up. We used Prentice-weighted Cox regression and random effects meta-analysis methods to estimate hazard ratios for T2D. Kaplan-Meier estimates of the cumulative incidence of T2D were calculated. BMI and WC were each independently associated with T2D, with WC being a stronger risk factor in women than in men. Risk increased across groups defined by BMI and WC; compared to low normal weight individuals (BMI 18.5-22.4 kg/m(2 with a low WC (102/88 cm. Among the large group of overweight individuals, WC measurement was highly informative and facilitated the identification of a subgroup of overweight people with high WC whose 10-y T2D cumulative incidence (men, 70 per 1,000 person-years; women, 44 per 1,000 person-years was comparable to that of the obese group (50-103 per 1,000 person-years in men and 28-74 per 1,000 person-years in women.WC is independently and strongly associated with T2D, particularly in women, and should be more widely measured for risk stratification. If targeted measurement is necessary for reasons of resource scarcity, measuring WC in overweight individuals may be an effective strategy, since it identifies a high-risk subgroup of individuals who could benefit from individualised preventive action.

Dietary ascorbic acid and subsequent change in body weight and waist circumference: associations may depend on genetic predisposition to obesity - a prospective study of three independent cohorts

Science.gov (United States)

2014-01-01

Background Cross-sectional data suggests that a low level of plasma ascorbic acid positively associates with both Body Mass Index (BMI) and Waist Circumference (WC). This leads to questions about a possible relationship between dietary intake of ascorbic acid and subsequent changes in anthropometry, and whether such associations may depend on genetic predisposition to obesity. Hence, we examined whether dietary ascorbic acid, possibly in interaction with the genetic predisposition to a high BMI, WC or waist-hip ratio adjusted for BMI (WHR), associates with subsequent annual changes in weight (∆BW) and waist circumference (∆WC). Methods A total of 7,569 participants’ from MONICA, the Diet Cancer and Health study and the INTER99 study were included in the study. We combined 50 obesity associated single nucleotide polymorphisms (SNPs) in four genetic scores: a score of all SNPs and a score for each of the traits (BMI, WC and WHR) with which the SNPs associate. Linear regression was used to examine the association between ascorbic acid intake and ΔBW or ΔWC. SNP-score × ascorbic acid interactions were examined by adding product terms to the models. Results We found no significant associations between dietary ascorbic acid and ∆BW or ∆WC. Regarding SNP-score × ascorbic acid interactions, each additional risk allele of the 14 WHR associated SNPs associated with a ∆WC of 0.039 cm/year (P = 0.02, 95% CI: 0.005 to 0.073) per 100 mg/day higher ascorbic acid intake. However, the association to ∆WC only remained borderline significant after adjustment for ∆BW. Conclusion In general, our study does not support an association between dietary ascorbic acid and ∆BW or ∆WC, but a diet with a high content of ascorbic acid may be weakly associated to higher WC gain among people who are genetically predisposed to a high WHR. However, given the quite limited association any public health relevance is questionable. PMID:24886192

Atomic layer deposited nanocrystalline tungsten carbides thin films as a metal gate and diffusion barrier for Cu metallization

Energy Technology Data Exchange (ETDEWEB)

Kim, Jun Beom; Kim, Soo-Hyun, E-mail: soohyun@ynu.ac.kr [School of Materials Science and Engineering, Yeungnam University, Gyeongsan-si 712-749 (Korea, Republic of); Han, Won Seok [UP Chemical 576, Chilgoedong, Pyeongtaek-si, Gyeonggi-do 459-050 (Korea, Republic of); Lee, Do-Joong [School of Engineering, Brown University, Providence, Rhode Island 02912 (United States)

2016-07-15

Tungsten carbides (WC{sub x}) thin films were deposited on thermally grown SiO{sub 2} substrates by atomic layer deposition (ALD) using a fluorine- and nitrogen-free W metallorganic precursor, tungsten tris(3-hexyne) carbonyl [W(CO)(CH{sub 3}CH{sub 2}C ≡ CCH{sub 2}CH{sub 3}){sub 3}], and N{sub 2} + H{sub 2} plasma as the reactant at deposition temperatures between 150 and 350 °C. The present ALD-WC{sub x} system showed an ALD temperature window between 200 and 250 °C, where the growth rate was independent of the deposition temperature. Typical ALD characteristics, such as self-limited film growth and a linear dependency of the film grown on the number of ALD cycles, were observed, with a growth rate of 0.052 nm/cycle at a deposition temperature of 250 °C. The ALD-WC{sub x} films formed a nanocrystalline structure with grains, ∼2 nm in size, which consisted of hexagonal W{sub 2}C, WC, and nonstoichiometric cubic β-WC{sub 1−x} phase. Under typical deposition conditions at 250 °C, an ALD-WC{sub x} film with a resistivity of ∼510 μΩ cm was deposited and the resistivity of the ALD-WC{sub x} film could be reduced even further to ∼285 μΩ cm by further optimizing the reactant pulsing conditions, such as the plasma power. The step coverage of ALD-WC{sub x} film was ∼80% on very small sized and dual trenched structures (bottom width of 15 nm and aspect ratio of ∼6.3). From ultraviolet photoelectron spectroscopy, the work function of the ALD-WC{sub x} film was determined to be 4.63 eV. Finally, the ultrathin (∼5 nm) ALD-WC{sub x} film blocked the diffusion of Cu, even up to 600 °C, which makes it a promising a diffusion barrier material for Cu interconnects.

Occupational health and safety surveillance and research using workers' compensation data.

Science.gov (United States)

Utterback, David F; Schnorr, Teresa M; Silverstein, Barbara A; Spieler, Emily A; Leamon, Tom B; Amick, Benjamin C

2012-02-01

Examine uses of US workers' compensation (WC) data for occupational safety and health purposes. This article is a summary of the proceedings from an invitational workshop held in September 2009 to discuss the use of WC data for occupational safety and health prevention purposes. Workers' compensation data systems, although limited in many ways, contain information such as medical treatments, their costs and outcomes, and disability causes that are unavailable from national occupational surveillance sources. Despite their limitations, WC records are collected in a manner consistent with many occupational health and safety surveillance needs. Reports are available on the use of WC data for surveillance and research purposes such as estimating the frequency, magnitude, severity, and cost of compensated injuries. Inconsistencies in WC data can limit generalization of research results.

Age-related differences in recommended anthropometric cut-off point validity to identify cardiovascular risk factors in ostensibly healthy women.

Science.gov (United States)

Subramoney, Sreevidya; Björkelund, Cecilia; Guo, Xinxin; Skoog, Ingmar; Bosaeus, Ingvar; Lissner, Lauren

2014-12-01

To investigate validity of widely recommended anthropometric and total fat percentage cut-off points in screening for cardiovascular risk factors in women of different ages. A population-based sample of 1002 Swedish women aged 38, 50, 75 (younger, middle-aged and elderly, respectively) underwent anthropometry, health examinations and blood tests. Total fat was estimated (bioimpedance) in 670 women. Sensitivity, specificity of body mass index (BMI; ≥25 and ≥30), waist circumference (WC; ≥80 cm and ≥88 cm) and total fat percentage (TF; ≥35%) cut-off points for cardiovascular risk factors (dyslipidaemias, hypertension and hyperglycaemia) were calculated for each age. Cut-off points yielding high sensitivity together with modest specificity were considered valid. Women reporting hospital admission for cardiovascular disease were excluded. The sensitivity of WC ≥80 cm for one or more risk factors was ~60% in younger and middle-aged women, and 80% in elderly women. The specificity of WC ≥80 cm for one or more risk factors was 69%, 57% and 40% at the three ages (p < .05 for age trends). WC ≥80 cm yielded ~80% sensitivity for two or more risk factors across all ages. However, specificity decreased with increasing age (p < .0001), being 33% in elderly. WC ≥88 cm provided better specificity in elderly women. BMI and TF % cut-off points were not better than WC. Validity of recommended anthropometric cut-off points in screening asymptomatic women varies with age. In younger and middle-age, WC ≥80 cm yielded high sensitivity and modest specificity for two or more risk factors, however, sensitivity for one or more risk factor was less than optimal. WC ≥88 cm showed better validity than WC ≥80 cm in elderly. Our results support age-specific screening cut-off points for women. © 2014 the Nordic Societies of Public Health.

Surprising conformers of the biologically important A·T DNA base pairs: QM/QTAIM proofs

Science.gov (United States)

Brovarets', Ol'ha O.; Tsiupa, Kostiantyn S.; Hovorun, Dmytro M.

2018-02-01

For the first time novel high-energy conformers – A·T(wWC) (5.36), A·T(wrWC) (5.97), A·T(wH) (5.78) and A·T(wrH) (ΔG=5.82 kcal•mol-1) were revealed for each of the four biologically important A·T(WC) DNA base pairs – Watson-Crick A·T(WC), reverse Watson-Crick A·T(rWC), Hoogsteen A·T(H) and reverse Hoogsteen A·T(rH) at the MP2/aug-cc-pVDZ//B3LYP/6-311++G(d,p) level of quantum-mechanical theory in the continuum with ɛ=4 under normal conditions. Each of these conformers possesses substantially non-planar wobble (w) structure and is stabilized by the participation of the two anti-parallel N6H/N6H'…O4/O2 and N3H…N6 H-bonds, involving the pyramidalized amino group of the A DNA base as an acceptor and a donor of the H-bonding. The transition states – TSA·T(WC)↔A·T(wWC), TSA·T(rWC)↔A·T(wrWC), TSA·T(H)↔A·T(wH) and TSA·T(rH)↔A·T(wrH), controlling the dipole-active transformations of the conformers from the main plane-symmetric state into the high-energy, significantly non-planar state and vice versa, were localized. They also possess wobble structures similarly to the high-energy conformers and are stabilized by the participation of the N6H/N6H'…O4/O2 and N3H…N6 H-bonds. Discovered conformers of the A·T DNA base pairs are dynamically stable short-lived structures (lifetime τ = (1.4-3.9) ps). Their possible biological significance and future perspectives have been briefly discussed.

Pollen aroma fingerprint of two sunflower (Helianthus annuus L.) genotypes characterized by different pollen colors.

Science.gov (United States)

Bertoli, Alessandra; Fambrini, Marco; Doveri, Silvia; Leonardi, Michele; Pugliesi, Claudio; Pistelli, Luisa

2011-09-01

Samples of fresh pollen grains, collected from capitula in full bloom from two genotypes of sunflower (Helianthus annuus L.) and characterized by a different color, i.e., white-cream (WC) and orange (O), were analyzed by the HS-SPME (headspacesolid phase microextraction)/GC/MS technique. This study defined for the first time the fingerprint of the sunflower pollen, separated from the disc flowers, to define its contribution to the inflorescence aroma. In the GC/MS fingerprints of the WC and O genotypes, 61 and 62 volatile compounds were identified, respectively. Monoterpene hydrocarbons (34% in O vs. 28% in WC) and sesquiterpene hydrocarbons (37% in O vs. 31% in WC) were ubiquitous in all samples analyzed and represented the main chemical classes. α-Pinene (21% in O vs. 20% in WC) and sabinene (11% in O vs. 6% in WC) were the dominant volatiles, but also a full range of aliphatic hydrocarbons and their oxygenated derivatives gave a decisive contribution to the aroma composition (10% in O vs. 12% in WC). In addition, dendrolasin (3% in O vs. 4% in WC) and some minor constituents such as (E)-hex-2-en-1-ol (0.4% in O vs. 0.1% in WC) were pointed out not only for their contribution to the pollen scent, but also for their well-known role in the plant ecological relationships. Having evaluated two pollen morphs with different carotenoid-based colors, the study sought to highlight also the presence of some volatile precursors or derivatives of these pigments in the aroma. However, the pollen aroma of the two selected genotypes made a specific chemical contribution to the sunflower inflorescence scent without any influence on carotenoid derivatives. 2011 Verlag Helvetica Chimica Acta AG, Zürich.

Waist circumference, body mass index, and employment outcomes.

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Kinge, Jonas Minet

2017-07-01

Body mass index (BMI) is an imperfect measure of body fat. Recent studies provide evidence in favor of replacing BMI with waist circumference (WC). Hence, I investigated whether or not the association between fat mass and employment status vary by anthropometric measures. I used 15 rounds of the Health Survey for England (1998-2013), which has measures of employment status in addition to measured height, weight, and WC. WC and BMI were entered as continuous variables and obesity as binary variables defined using both WC and BMI. I used multivariate models controlling for a set of covariates. The association of WC with employment was of greater magnitude than the association between BMI and employment. I reran the analysis using conventional instrumental variables methods. The IV models showed significant impacts of obesity on employment; however, they were not more pronounced when WC was used to measure obesity, compared to BMI. This means that, in the IV models, the impact of fat mass on employment did not depend on the measure of fat mass.

Work-related trauma, PTSD, and workers compensation legislation: Implications for practice and policy.

Science.gov (United States)

Wise, Edward A; Beck, J Gayle

2015-09-01

The current review examines work-related traumatic events, with particular focus on posttraumatic stress disorder (PTSD) as a potential mental health outcome. Despite considerable empirical knowledge about trauma and PTSD, a gap exists with respect to laws undergirding Workers Compensation (WC) insurance coverage for work-related mental health injuries. In this article, state and federal WC statutes are examined with an eye toward coverage of PTSD following work-related trauma. Examples of differences between states, as well as state-specific idiosyncratic facets of WC laws, are discussed. Federal WC programs are also examined. Two policy issues are highlighted: (a) lack of parity between WC coverage for work-related physical versus mental health injuries and (b) lack of reliance on psychological science in scripting legislation and determining WC benefits. The cost of untreated PTSD following work-related trauma is examined, focusing on costs to the individual, the employer, and society at large. The authors provide 3 recommendations designed to address discrepancies related to compensable psychological injuries following work-related trauma exposure. (c) 2015 APA, all rights reserved).

The Search for a Cold War Grand Strategy: NSC 68 & 162

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2014-05-22

Harper Collins Publishers, 1990. Chandler , Alfred D., Jr., and Louis Galamos Jr. The Papers of Dwight D. Eisenhower. Baltimore, MD, 1970. Cutler...76Alfred D. Chandler Jr., and Louis Galamos Jr., The Papers of Dwight D. Eisenhower (Baltimore, MD, 1970), Vol. 11, 1312; Vol. 8, 1609. 77Ibid

76 FR 28955 - Proposed Information Collection; Comment Request

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2011-05-19

... Corporation is soliciting comments concerning its revised Martin Luther King, Jr. Day of Service Application... King, Jr. Day of Service Grants is to mobilize more Americans to observe the Martin Luther King, Jr.... Background The Martin Luther King, Jr. Day of Service Grant application is completed by applicant...

Relationship between Anthropometric Measures and Cardiovascular Risk Factors in Children and Adolescents

Energy Technology Data Exchange (ETDEWEB)

Burgos, Miria Suzana [Universidade de Santa Cruz do Sul - UNISC, Santa Cruz do Sul, RS (Brazil); Programa de Pós-graduação - Mestrado em Promoção da Saúde - UNISC, Santa Cruz do Sul, RS (Brazil); Burgos, Leandro Tibiriçá; Camargo, Marcelo Dias [Grupo de Pesquisa em Cardiologia do Exercício HCPA/UFRGS, Porto Alegre, RS (Brazil); Franke, Silvia Isabel Rech; Prá, Daniel [Universidade de Santa Cruz do Sul - UNISC, Santa Cruz do Sul, RS (Brazil); Programa de Pós-graduação - Mestrado em Promoção da Saúde - UNISC, Santa Cruz do Sul, RS (Brazil); Silva, Antônio Marcos Vargas da [Universidade Federal de Santa Maria - UFSM, Santa Maria, RS (Brazil); Borges, Tássia Silvana; Todendi, Pâmela Ferreira [Universidade de Santa Cruz do Sul - UNISC, Santa Cruz do Sul, RS (Brazil); Programa de Pós-graduação - Mestrado em Promoção da Saúde - UNISC, Santa Cruz do Sul, RS (Brazil); Reckziegel, Miriam Beatris [Universidade de Santa Cruz do Sul - UNISC, Santa Cruz do Sul, RS (Brazil); Reuter, Cézane Priscila, E-mail: cpreuter@hotmail.com [Universidade de Santa Cruz do Sul - UNISC, Santa Cruz do Sul, RS (Brazil); Programa de Pós-graduação - Mestrado em Promoção da Saúde - UNISC, Santa Cruz do Sul, RS (Brazil)

2013-10-15

Obesity has been identified as an important risk factor in the development of cardiovascular diseases; however, other factors, combined or not with obesity, can influence cardiovascular risk and should be considered in cardiovascular risk stratification in pediatrics. To analyze the association between anthropometry measures and cardiovascular risk factors, to investigate the determinants to changes in blood pressure (BP), and to propose a prediction equation to waist circumference (WC) in children and adolescents. We evaluated 1,950 children and adolescents, aged 7 to 18 years. Visceral fat was assessed by WC and waist hip relationship, BP and body mass index (BMI). In a randomly selected subsample of these volunteers (n = 578), total cholesterol, glucose and triglycerides levels were evaluated. WC was positively correlated with BMI (r = 0.85; p < 0.001) and BP (SBP r = 0.45 and DBP = 0.37; p < 0.001). Glycaemia and triglycerides showed a weak correlation with WC (r = 0.110; p = 0.008 e r = 0.201; p < 0.001, respectively). Total cholesterol did not correlate with any of the variables. Age, BMI and WC were significant predictors on the regression models for BP (p < 0.001). We propose a WC prediction equation for children and adolescents: boys: y = 17.243 + 0.316 (height in cm); girls: y = 25.197 + 0.256 (height in cm). WC is associated with cardiovascular risk factors and presents itself as a risk factor predictor of hypertension in children and adolescents. The WC prediction equation proposed by us should be tested in future studies.

Relationship between Anthropometric Measures and Cardiovascular Risk Factors in Children and Adolescents

International Nuclear Information System (INIS)

Burgos, Miria Suzana; Burgos, Leandro Tibiriçá; Camargo, Marcelo Dias; Franke, Silvia Isabel Rech; Prá, Daniel; Silva, Antônio Marcos Vargas da; Borges, Tássia Silvana; Todendi, Pâmela Ferreira; Reckziegel, Miriam Beatris; Reuter, Cézane Priscila

2013-01-01

Obesity has been identified as an important risk factor in the development of cardiovascular diseases; however, other factors, combined or not with obesity, can influence cardiovascular risk and should be considered in cardiovascular risk stratification in pediatrics. To analyze the association between anthropometry measures and cardiovascular risk factors, to investigate the determinants to changes in blood pressure (BP), and to propose a prediction equation to waist circumference (WC) in children and adolescents. We evaluated 1,950 children and adolescents, aged 7 to 18 years. Visceral fat was assessed by WC and waist hip relationship, BP and body mass index (BMI). In a randomly selected subsample of these volunteers (n = 578), total cholesterol, glucose and triglycerides levels were evaluated. WC was positively correlated with BMI (r = 0.85; p < 0.001) and BP (SBP r = 0.45 and DBP = 0.37; p < 0.001). Glycaemia and triglycerides showed a weak correlation with WC (r = 0.110; p = 0.008 e r = 0.201; p < 0.001, respectively). Total cholesterol did not correlate with any of the variables. Age, BMI and WC were significant predictors on the regression models for BP (p < 0.001). We propose a WC prediction equation for children and adolescents: boys: y = 17.243 + 0.316 (height in cm); girls: y = 25.197 + 0.256 (height in cm). WC is associated with cardiovascular risk factors and presents itself as a risk factor predictor of hypertension in children and adolescents. The WC prediction equation proposed by us should be tested in future studies

Associations of body mass index and waist circumference with: energy intake and percentage energy from macronutrients, in a cohort of australian children

Science.gov (United States)

2011-01-01

Background It is evident from previous research that the role of dietary composition in relation to the development of childhood obesity remains inconclusive. Several studies investigating the relationship between body mass index (BMI), waist circumference (WC) and/or skin fold measurements with energy intake have suggested that the macronutrient composition of the diet (protein, carbohydrate, fat) may play an important contributing role to obesity in childhood as it does in adults. This study investigated the possible relationship between BMI and WC with energy intake and percentage energy intake from macronutrients in Australian children and adolescents. Methods Height, weight and WC measurements, along with 24 h food and drink records (FDR) intake data were collected from 2460 boys and girls aged 5-17 years living in the state of Queensland, Australia. Results Statistically significant, yet weak correlations between BMI z-score and WC with total energy intake were observed in grades 1, 5 and 10, with only 55% of subjects having a physiologically plausible 24 hr FDR. Using Pearson correlations to examine the relationship between BMI and WC with energy intake and percentage macronutrient intake, no significant correlations were observed between BMI z-score or WC and percentage energy intake from protein, carbohydrate or fat. One way ANOVAs showed that although those with a higher BMI z-score or WC consumed significantly more energy than their lean counterparts. Conclusion No evidence of an association between percentage macronutrient intake and BMI or WC was found. Evidently, more robust longitudinal studies are needed to elucidate the relationship linking obesity and dietary intake. PMID:21615883

Novel diamond-coated tools for dental drilling applications.

Science.gov (United States)

Jackson, M J; Sein, H; Ahmed, W; Woodwards, R

2007-01-01

The application of diamond coatings on cemented tungsten carbide (WC-Co) tools has been the subject of much attention in recent years in order to improve cutting performance and tool life in orthodontic applications. WC-Co tools containing 6% Co metal and 94% WC substrate with an average grain size of 1 - 3 microm were used in this study. In order to improve the adhesion between diamond and WC substrates it is necessary to etch cobalt from the surface and prepare it for subsequent diamond growth. Alternatively, a titanium nitride (TiN) interlayer can be used prior to diamond deposition. Hot filament chemical vapour deposition (HFCVD) with a modified vertical filament arrangement has been employed for the deposition of diamond films to TiN and etched WC substrates. Diamond film quality and purity has been characterized using scanning electron microscopy (SEM) and micro Raman spectroscopy. The performances of diamond-coated WC-Co tools, uncoated WC-Co tools, and diamond embedded (sintered) tools have been compared by drilling a series of holes into various materials such as human tooth, borosilicate glass, and acrylic tooth materials. Flank wear has been used to assess the wear rates of the tools when machining biomedical materials such as those described above. It is shown that using an interlayer such as TiN prior to diamond deposition provides the best surface preparation for producing dental tools.

Centile Curves and Reference Values for Height, Body Mass, Body Mass Index and Waist Circumference of Peruvian Children and Adolescents

Science.gov (United States)

Bustamante, Alcibíades; Freitas, Duarte; Pan, Huiqi; Katzmarzyk, Peter T.; Maia, José

2015-01-01

This study aimed to provide height, body mass, BMI and waist circumference (WC) growth centile charts for school-children, aged 4–17 years, from central Peru, and to compare Peruvian data with North-American and Argentinean references. The sample consisted of 8753 children and adolescents (4130 boys and 4623 girls) aged 4 to 17 years, from four Peruvian cities: Barranco, La Merced, San Ramón and Junín. Height, body mass and WC were measured according to standardized techniques. Centile curves for height, body mass, BMI and WC were obtained separately for boys and girls using the LMS method. Student t-tests were used to compare mean values. Overall boys have higher median heights than girls, and the 50th percentile for body mass increases curvilinearly from 4 years of age onwards. In boys, the BMI and WC 50th percentiles increase linearly and in girls, the increase presents a curvilinear pattern. Peruvian children are shorter, lighter and have higher BMI than their counterparts in the U.S. and Argentina; in contrast, age and sex-specific WC values are lower. Height, body mass and WC of Peruvian children increased with age and variability was higher at older ages. The growth patterns for height, body mass, BMI and WC among Peruvian children were similar to those observed in North-American and Argentinean peers. PMID:25761169